<PAGE>
 
                                 EXHIBIT 10.16

                COMMERCIAL LEASE AGREEMENT BETWEEN EBP 3, LTD.
              AND MILLIPORE CORPORATION WITH RESPECT TO PREMISES
                            LOCATED IN ALLEN, TEXAS

<PAGE>
 
                                LEASE AGREEMENT
                                ---------------


     This Lease Agreement (this "LEASE") is entered into by EBP 3, LTD., a Texas
                                 -----                                          
limited partnership ("LANDLORD"), and MILLIPORE CORPORATION, a Massachusetts
corporation ("TENANT").

     1.   PREMISES, TERM, AND BUILDING SHELL.
          ----------------------------------

          (a)  Landlord leases to Tenant, and Tenant leases from Landlord, the
real property described on Exhibit A-1 (the "LAND"), which includes the
                           -----------       ----                      
approximately 178,013 square foot building depicted on Exhibit A-2 (the
                                                       -----------     
"BUILDING") being constructed on the Land, subject to the terms and conditions
---------                                                                     
in this Lease.  The term "PREMISES" means the Land, Building, and related
                          --------                                       
improvements.

          (b)  The Lease term shall be 120 months (the "TERM", which defined
                                                        ---- 
term shall include all renewals and extensions of the Term), beginning on the
earlier of (1) the date Tenant begins conducting business in the Premises and
(2) June 1, 1998 (the "COMMENCEMENT DATE"); however, if Tenant is delayed in
                       -----------------                                    
substantially completing the interior improvements in the Building because the
shell of the Building (the "BUILDING SHELL") was not in a dried-in condition
                            --------------                                  
sufficient to allow Tenant to begin its interior tenant improvement work on
February 1, 1998, then the Commencement Date will be delayed until the earlier
of: (A) June 1, 1998, plus the number of days obtained by performing the
following calculation:

               X - Y; where,

      X = the number of days after February 1, 1998, that the Building Shell was
      not in such a dried-in condition; and

      Y = the number of days of delay in achieving such a dried-in condition
      caused by a Tenant Party;

or (B) the date Tenant begins conducting business in the Premises.  If the
Commencement Date is not the first day of a calendar month, then the Term shall
end on the last day of the 120-month period that begins on the first day of the
first full calendar month of the Term.  Within ten days after either party's
requests therefor, Landlord and Tenant will execute an agreement setting forth
the Commencement Date.

          (c)  Landlord shall construct the Building Shell in accordance with
Exhibit B.  By occupying the Premises, Tenant shall have accepted the Premises
---------                                                                     
in their condition, subject to completion of any unperformed items necessary to
complete the Building Shell as provided in Exhibit B.  Notwithstanding anything
                                           ---------                           
in this Lease to the contrary, if the Building Shell is not substantially
completed by May 1, 1998, plus the number of days of delay in achieving
substantial completion caused by force majeure 

<PAGE>
 
events described in Section 23.(c) and the number of days of delay in achieving
substantial completion of the Building Shell caused by a Tenant Party (the
"TERMINATION ELECTION DATE"), then Tenant may terminate this Lease by,        
 -------------------------   
delivering written notice thereof to Landlord before the earlier of the date the
Building Shell is substantially completed or ten days after the Termination
Election Date.

     2.   BASE RENT, SECURITY DEPOSIT AND ADDITIONAL RENT,
          ------------------------------------------------

          (a)  Tenant shall pay to Landlord "BASE RENT", in advance, without
                                             ---------                      
demand, deduction or set off (except as herein provided), equal to the following
amounts for the following periods of time:

           Time Period                                 Monthly Base Rent
           -----------                                 -----------------
           1 through 60                                    $67,793.29
           61 through end of initial Term                  $78,029.03

The first monthly installment of Base Rent shall be due on the date hereof;
thereafter, monthly installments of Base Rent shall be due on the first day of
each calendar month following the Commencement Date. If the Term begins on a day
other than the first day of a month or ends on a day other than the last day of
a month, the Base Rent and additional rent under Section 2.(c) for such partial
month shall be prorated.

          (b)  Tenant shall deposit with Landlord on the date hereof $67,793.28
(the "SECURITY DEPOSIT"), which shall be held by Landlord to secure Tenant's
      ----------------                                                      
obligations under this Lease; however, the Security Deposit is not an advance
rental deposit or a measure of Landlord's damages for an Event of Default
(defined below).  Landlord may use any portion of the Security Deposit to
satisfy Tenant's unperformed obligations hereunder, without prejudice to any of
Landlord's other remedies.  If so used, Tenant shall pay Landlord an amount that
will restore the Security Deposit to its original amount upon request.  In
connection with any waiver of a Tenant default or modification of this Lease,
Landlord may require that Tenant provide Landlord with an additional amount to
be held as part of the Security Deposit.  The unused portion of the Security
Deposit plus 5% per annum thereon (compounded annually) will be returned to
Tenant within a reasonable time after the end of the Term (not to exceed 30
days), provided that Tenant has fully and timely performed its obligations
hereunder throughout the Term.

          (c)  Tenant shall pay, as additional rent, all costs incurred in
operating, managing, and maintaining the Premises (collectively, "OPERATING
                                                                  ---------
EXPENSES" including the following items: (1) Taxes (defined below); (2) the cost
--------                                                                        
of insurance; (3) the cost of repairs and replacement of the items described in
Section 4.(b), management fees (which shall not exceed 3% of the gross rent) and
related out-of-pocket expenses of the manager, landscape maintenance and
replacement, security service (if provided), sewer service (if provided), and
trash service (if provided); (4) the cost of dues, assessments, and other
charges applicable to the Premises payable to any property or community owner
association under restrictive covenants or deed restrictions to which the
Premises are 

<PAGE>
 
subject that affect all property subject thereto in a similar manner; and (5)
alterations, additions, and improvements relating to the items described in
Section 4.(b) made by Landlord to comply with Law (defined below). Additional
rent wider this Section 2.(c) shall be payable by Tenant to Landlord in monthly
installments equal to 1/12 of Landlord's good faith estimate of annual Operating
Expenses. The initial monthly payments are based upon Landlord's good faith
estimate of the Operating Expenses for the year in question, and shall be
increased or decreased annually to reflect the projected actual Operating
Expenses for that year.

          Within 90 days after each calendar year or as soon thereafter as is
reasonably practicable, Landlord shall deliver to Tenant a statement setting
forth the actual Operating Expenses for such year (an "ANNUAL OPERATING EXPENSE
                                                       ------------------------
STATEMENT".  Each Annual Operating Expense Statement shall set forth a line item
---------                                                                       
detail comparing the actual Operating Expenses for such calendar year to the
Operating Expenses for the preceding calendar year, the estimated payments paid
by Tenant toward Operating Expenses during the calendar year for which such
statement was prepared and an estimate of Tenant's obligation for Operating
Expenses for the next calendar year.  If Tenant's total payments in respect of
Operating Expenses for any year are less than the Operating Expenses for that
year, Tenant shall pay the difference to Landlord within 30 days after
Landlord's request therefor; if such payments are more than the Operating
Expenses, Landlord shall pay to Tenant such excess within 30 days after Landlord
delivers to Tenant the applicable Annual Operating Expense Statement.  Operating
Expenses shall not include the following: (A) any costs for interest,
amortization, or other payments on loans to Landlord; (B) federal income taxes
imposed on or measured by the income of Landlord from the operation of the
Premises; (C) rents under ground leases; (D) costs incurred in selling,
syndicating, financing, mortgaging, or hypothecating any of Landlord's interests
in the Premises; (E) costs incurred by Landlord to repair any damage to the
Building to the extent Landlord is reimbursed by insurance proceeds therefor;
(F) items which Landlord is obligated to perform under Section 4.(a); (G) costs
arising from latent defects in the Building Shell and other improvements
initially installed in the Premises pursuant to the Shell Plans; and (H) costs
incurred for services performed by an affiliate of either Landlord or its
building manager to the extent the cost thereof exceeds market rates for
comparable services.  There shall be no duplication of costs for reimbursements
in calculating Operating Expenses.  The amounts of the initial monthly Base Rent
and Operating Expenses (and the part thereof attributable to Taxes) are as
follows:

<TABLE> 
<CAPTION> 
     <S>                                                             <C> 
     Base Rent (Section 2.(a)).......................................$67,793.28
     Operating Expenses, excluding Taxes (Section 2.(c)).............$ 5,192.05
     Taxes (Sections 2.(c) and 3.(a))............................... $10,384.09

     Total initial monthly payment.................................. $83,369.42
                                                                     ==========
</TABLE> 

The first monthly installment of additional rent under this Section 2.(c) shall
be due on the date hereof, thereafter, monthly installments of such additional
rent shall be due on the first day of each calendar month following the
Commencement Date.

<PAGE>
 
          (d)  If any payment required of Tenant under this Lease for Base Rent
and Operating Expenses is not paid by the Delinquent Payment Date (defined
below), Landlord may charge Tenant a fee equal to 5% of the delinquent payment
to reimburse Landlord for its cost and inconvenience incurred as a consequence
of Tenant's delinquency.  "DELINQUENT PAYMENT DATE" means, with respect to each
                           -----------------------                             
payment of Base Rent and Operating Expenses due from Tenant under this Lease,
the fifth day after Landlord delivers to Tenant written notice that the payment
in question has not been paid when due; however, if Landlord has previously
notified Tenant that Tenant has failed to pay rent when due twice during the 12-
month period preceding the delinquent payment in question, then the Delinquent
Payment Date for that payment shall mean the day after that payment was due.

          (e)  All payments and reimbursements required to be made by Tenant
under this Lease shall constitute "RENT" (herein so called) and shall be payable
                                   ----                                         
without demand, deduction or set off (except as expressly set forth herein).

          (f)  INSPECTION RIGHT.  After giving Landlord 30-days' prior written
               -----------------                                              
notice thereof, Tenant may inspect or audit Landlord's records relating to
Operating Expenses for any periods of time within two years before the audit or
inspection; however, no audit or inspection shall extend to periods of time
before the Commencement Date. Tenant's audit or inspection shall be conducted
only during business hours reasonably designated by Landlord. Tenant shall pay
the cost of such audit or inspection, including a reasonable amount to reimburse
Landlord for its out-of-pocket costs allocable to the inspection or audit,
unless the total Operating Expenses charged to Tenant for the time period in
question is determined to be in error, and, as a result thereof, Tenant paid to
Landlord $3,000 more than the actual Operating Expenses due for such time
period, in which case Landlord shall pay the audit cost. Tenant may not conduct
an inspection or have an audit performed more than once during any calendar
year. If such inspection or audit reveals that an error was made in the
Operating Expenses previously charged to Tenant, then Landlord shall refund to
Tenant any overpayment of any such costs, or Tenant shall pay to Landlord any
underpayment of any such costs, as the case may be, within 30 days after
notification thereof. Tenant shall maintain the results of each such audit or
inspection confidential and shall not be permitted to use any third party to
perform such audit or inspection, other than an independent firm of certified
public accountants reasonably acceptable to Landlord which agrees with Landlord
in writing to maintain the results of such audit or inspection confidential.

          (g)  When calculating Operating Expenses, Landlord shall take into
account all abatements (including, without limitation, tax abatements),
exemptions, and discounts, such that Tenant shall only be obligated to pay the
actual Operating Expenses. Landlord shall cooperate with Tenant in obtaining tax
abatements, discounts, and exemptions, provided that Tenant reimburses Landlord
for all out-of-pocket costs incurred by Landlord in connection therewith.

<PAGE>
 
     3.   TAXES.
          ------

          (a)  Landlord shall pay all taxes, assessments and governmental
charges whether federal, state, county, or municipal and whether they are
imposed by taxing or management districts or authorities presently existing or
hereafter created (collectively, "TAXES") that accrue against the Premises. If,
                                  ------                        
during the Term, there is levied, assessed or imposed on Landlord a capital levy
or other tax directly on the rent or a franchise tax, assessment, levy or charge
measured by or based, in whole or in part, upon rent, then all such taxes,
assessments, levies or charges, or the part thereof so measured or based, shall
be included within the term "Taxes".

          (b)  Tenant shall (1) before delinquency pay all taxes levied or
assessed against any personal property, fixtures or alterations placed in the
Premises and (2) upon the request of Landlord, deliver to Landlord receipts from
the applicable taxing authority or other evidence acceptable to Landlord to
verify that such taxes have been paid.  If any such taxes are levied or assessed
against Landlord or Landlord's property and (A) Landlord pays them or (B) the
assessed value of Landlord's property is increased thereby and Landlord pays the
increased taxes, then Tenant shall pay to Landlord such taxes within ten days
after Landlord's request therefor.

     4.   LANDLORD'S MAINTENANCE,
          -----------------------

          (a)  This Lease is intended to be a net lease. Accordingly, Landlord's
maintenance obligations are limited to maintenance of the Building's roof,
foundation piers, structural slab, and structural members of the exterior walls
(collectively, "BUILDING'S STRUCTURE"); painting of exterior walls; and caulking
                --------------------                                            
of tilt panels and windows; however, Landlord shall not be responsible (1) for
any such work until Tenant delivers to Landlord written notice of the need
therefor or (2) for alterations to the Building's Structure required by Law
because of Tenant's specific use of or particular activity (e.g., a specific
type of research and development) conducted in the Premises (which alterations
shall be performed by Tenant) as opposed to alterations required by Law in
general for office, warehouse, manufacturing and research and development use.
Landlord shall promptly make all such repairs after it has received notice of
the need therefor.  The Building's Structure does not include windows (other
than caulking thereof) or components thereof (including flashing, etc.), glass
or plate glass, doors, special store fronts or office entries, all of which
shall be maintained by Tenant.  Landlord's liability for any defects, repairs,
replacement or maintenance for which Landlord is responsible hereunder shall be
limited to the cost of performing such work.

          (b)  Additionally, Landlord shall maintain the parking areas,
driveways, alleys and grounds surrounding the Premises in a clean and sanitary
condition, consistent with the operation of a first-class
office/warehouse/research/manufacturing building, including prompt maintenance,
repairs and replacements of (1) any drill or spur track servicing the Premises,
(2) the exterior portions of the Premises, (3) sprinkler systems and sewage
lines, and (4) any other items normally associated with the foregoing.  All
costs 

<PAGE>
 
incurred by Landlord in connection therewith (other than the painting of
exterior walls and caulking of tilt walls) shall be Operating Expenses.
Notwithstanding the foregoing, Landlord shall have no responsibility for
maintaining any portion of Tenant's Operational Areas (defined below), such
areas shall be under the sole dominion and control of Tenant.

     5.   TENANT'S MAINTENANCE AND REPAIR OBLIGATIONS.
          --------------------------------------------

          (a)  Tenant shall maintain all parts of the Premises (except for
maintenance work which Landlord is expressly responsible for under Section
4.(a)) in good condition and promptly make all necessary repairs and
replacements to the Premises.  Tenant shall repair and pay for any damage caused
by a Tenant Party (defined below), to the extent Landlord is not reimbursed
therefor by insurance proceeds.

          (b)  Tenant shall maintain the hot water equipment and the heating,
air condition, and ventilation equipment and system (the "HVAC SYSTEM") in good
                                                          -----------          
repair and condition and in accordance with Law and with such equipment
manufacturers' suggested operation/maintenance service program; such obligation
shall include replacement of all equipment necessary to maintain such equipment
and system in good working order.  At least 14 days before the end of the Term,
Tenant shall deliver to Landlord a certificate from an engineer reasonably
acceptable to Landlord certifying that the hot water equipment and the HVAC
System are then in good repair and working order.

          (c)  Tenant shall be responsible for all pest control in the Premises.

     6.   ALTERATIONS. Except as provided below, Tenant shall not make any
          -----------                                                    
alterations, additions or improvements to the Premises without the prior written
consent of Landlord which shall not be unreasonably withheld.  Landlord may not
withhold its consent to any alteration, addition or improvement unless, in
Landlord's reasonable determination, the installation or use of such item would
violate Law, would cause the Premises or the use thereof to be in violation of
Law, would alter or adversely affect the Building's Structure, or would increase
Landlord's obligations under Section 4.(a) (unless Tenant agrees to pay all
additional costs incurred in connection therewith or as a result thereof).
Landlord shall not be required to notify Tenant of whether it consents to any
alteration, addition or improvements until it (a) has received plans and
specifications therefor which are sufficiently detailed to allow construction of
the work depicted thereon to be performed in a good and workmanlike manner, and
(b) has had a reasonable opportunity to review them (not to exceed ten business
days).  If the alteration, addition or improvement will affect the Building's
Structure, HVAC System, life-safety, or mechanical, electrical, or plumbing
systems, then the plans and specifications therefor must be prepared by a
licensed engineer reasonably acceptable to Landlord.  Landlord's approval of any
plans and specifications shall not be a representation that the plans or the
work depicted thereon will comply with Law or be adequate for any purpose, belt
shall merely be Landlord's consent to performance of the work.  Upon completion
of any alteration, addition, or improvement, Tenant shall deliver to Landlord
accurate, reproducible as built plans therefor.  Unless Landlord specifies in
writing otherwise and 

<PAGE>
 
except as provided in Section 16, all alterations, additions, and improvements
shall be Landlord's property when installed in the Premises. All work performed
by a Tenant Party in the Premises (including that relating to the installations,
repair, replacement, or removal of any item) shall be performed in accordance
with Law, in a good and workmanlike manner, and so as not to damage the
Building's Structure.

          Notwithstanding the foregoing, after the initial tenant improvements
have been installed by Tenant in the Premises and a certificate of occupancy has
been issued therefor, Tenant shall not be required to obtain Landlord's consent
for repainting, recarpeting, or other alterations totalling less than $50,000 in
any single instance or series of related alterations performed within a six-
month period, provided that such alterations do not alter or adversely affect
the Building's Structure.  Tenant shall pay to Landlord or its designated agent
a construction management fee in connection with the design and installation of
the initial tenant improvements installed in the Premises by Tenant equal to
$25,000; such payment shall be made on or before the Commencement Date.  Tenant
shall not be entitled to occupy the Premises unless Tenant has obtained and
delivered to Landlord a copy of the certificate of occupancy therefor.

     7.   SIGNS.  Provided that the maintenance thereof complies with all
          -----                                                          
Laws, and Tenant has received all approvals, consents, and permits required by
Law therefor, Tenant may install and maintain one monument sign on the Premises
and one sign on each of the two exterior facade panels placed on the Building by
Landlord.  Landlord shall pay for the cost of placing the exterior facade panels
on the Building, and Tenant shall bear all other costs in connection with all
signs maintained at the Premises (including the cost of the signage to be placed
on the Building's sign panel).  Each sign's design, color scheme, location,
material composition, and method of installation must be approved by Landlord.
Tenant shall maintain such signs in a good, clean, and safe condition in
accordance with all Laws.  Tenant shall repair all damage caused by the
installation, use, maintenance, and removal of the signs and, upon their
removal, restore the Premises where such signs were located to their condition
immediately before the installation thereof (ordinary wear and tear excepted,
other than any discoloration caused thereby).  Within ten days after the earlier
of (A) termination of Tenant's right to possess the Premises or (B) the end of
the Term, Tenant shall remove the signs and perform all restoration work as
provided above.  If Tenant fails to do so within such ten-day period, Landlord
may, without compensation to Tenant, perform such work and dispose of the signs
in any manner it deems appropriate or deem such signs abandoned and, after
removing Tenant's logo therefrom, use such signs; Tenant shall pay to Landlord
all reasonable costs incurred in connection therewith within 30 days after
Landlord's request therefor.

     8.   UTILITIES.  Tenant shall obtain and pay for all water, gas,
          ---------                                                  
electricity, heat, telephone, sewer, sprinkler charges and other utilities and
services used at the Premises, together with any taxes, penalties, surcharges,
maintenance charges, and the like pertaining to the Tenant's use of the
Premises. If Tenant fails to pay for such amounts, Landlord may do so, in which
case, Tenant shall reimburse Landlord therefor within ten

<PAGE>
 
days after Landlord's request. Landlord shall not be liable for any interruption
or failure of utility service to the Premises.

          Notwithstanding the foregoing, if Tenant is prevented from making
reasonable use of the Premises for more than three consecutive days because of
the unavailability of any such service and such unavailability was primarily
caused by Landlord's negligence or willful misconduct, then Tenant shall be
entitled to a reasonable abatement of rent for each consecutive day after the
expiration of such three-day period that Tenant is so prevented from making
reasonable use of the Premises.

     9.   INSURANCE; SELF-INSURANCE.
          ------------------------- 

          (a)  Tenant shall maintain (1) workers' compensation insurance (with a
mutual waiver of subrogation endorsement reasonably acceptable to Landlord) and
commercial general liability insurance (with contractual liability endorsement),
including personal injury and property damage in the amount of $5,000,000 per
occurrence and (2) fire and extended coverage insurance covering (A) the
replacement cost of all alterations, additions, partitions and improvements
installed in the Premises, (B) the replacement cost of all of Tenant's personal
property in the Premises, and (C) loss of profits in the event of an insured
peril damaging the Premises.  Such policies shall (i) name Landlord, Landlord's
agents, and their respective affiliates (defined below), as additional insureds
(and as loss payees on the fire and extended coverage insurance), (ii) be issued
by an insurance company acceptable to Landlord with a minimum AM Best rating of
A:X or better and licensed to do business in Texas, (iii) provide that such
insurance may not be cancelled unless 30 days' prior written notice is first
given to Landlord, (iv) be delivered to Landlord by Tenant before the
Commencement Date and at least 30 days before each renewal thereof (or
certificates thereof or other evidence thereof reasonably acceptable to Landlord
may be delivered), and (v) provide primary coverage to Landlord when any policy
issued to Landlord is similar or duplicate in coverage, in which case Landlord's
policy shall be excess over Tenant's policies.

          (b)  SELF-INSURANCE.  Tenant may provide self-insurance in lieu of the
               --------------                                                   
insurance required in Section 9.(a)(2), whether by the establishment of an
insurance fund or reserve to be held and applied to make good losses from
casualties, or otherwise, which conforms to the practice of large corporations
maintaining systems of self-insurance.  As a condition to establishing a self-
insurance plan in lieu of the insurance provided in Section 9.(a)(2), Tenant
shall deliver to Landlord the following: (1) a certificate of an independent
actuary or other independent, qualified person reasonably acceptable to Landlord
stating that the self-insurance plan is adequate to provide the protection of
the insurance policies described in Section 9.(a)(2) and (2) a balance sheet as
of the end of the most recent quarter of the then-current fiscal year of Tenant
(or, if the first quarter in such fiscal year has not expired, the last quarter
of the previous fiscal year), prepared by a national firm of certified public
accountants (reasonably acceptable to Landlord) in accordance with generally
accepted accounting principles consistently applied ("GAAP"), accompanied by
                                                      ----                  
such accounting firm's unqualified opinion that the tangible net worth of Tenant
exceeds 

<PAGE>
 
$100,000,000. Thereafter, Tenant shall deliver to Tenant as soon as available
(and in any event within 45 days) after the end of each fiscal year, a balance
sheet for such fiscal year, prepared by a national firm of certified public
accountants (reasonably acceptable to Landlord) in accordance with GAAP,
accompanied by such accounting firm's unqualified opinion that the tangible net
worth of Tenant exceeds $100,000,000. If any time Tenant's tangible net worth is
less than $100,000,000, Tenant shall be required to immediately obtain and
maintain the insurance provided in Section 9.(a)(2). "TANGIBLE NET WORTH" means
                                                      ------------------       
the excess of total assets over total liabilities (in each case, determined in
accordance with GAAP) excluding from the determination of total assets all
assets which would be classified as intangible assets under GAAP, including
limitation, goodwill, licenses, patents, trademarks, trade names, copyrights,
and franchises.

          (c)  CASUALTY INSURANCE.  Landlord shall maintain insurance insuring
               ------------------                                             
the Building Shell against the perils included in the Special Causes of Loss
form including, but not limited to, fire, lightning, extended coverage,
vandalism and malicious mischief in an amount not less than 80% of the
replacement cost thereof. Landlord has the option, but not the obligation, to
insure the Premises for loss caused by earthquake or flood. Such insurance shall
be for the sole benefit of Landlord and under its sole control. Landlord shall
not be obligated to insure furniture, equipment, machinery, goods or supplies of
Tenant which Tenant may keep or maintain at the Premises or any leasehold
improvements, additions or alterations in the Premises.

     10.  CASUALTY DAMAGE.
          --------------- 

          (a)  Tenant immediately shall give written notice to Landlord of any
damage to the Premises. Within 30 days after Landlord has notice of the damage
in question, Landlord shall deliver to Tenant its good faith estimate of the
time necessary to complete Landlord's work with respect to the damage in
question (the "DAMAGE ESTIMATE"). If the Premises are totally destroyed by an
               ---------------                                                
insured peril, or so damaged by an insured peril that, in Landlord's good faith
estimation, rebuilding or repairs cannot be substantially completed within nine
months after the date of Landlord's actual knowledge of such damage, then either
Landlord or (if a Tenant Party did not cause such damage) Tenant may terminate
this Lease by delivering to Landlord written notice thereof within 15 days after
Landlord delivers to Tenant the Damage Estimate, in which case, the rent shall
be abated during the unexpired portion of this Lease, effective upon the date
such damage occurred, and Tenant shall pay to Landlord the amount of the
deductible applicable to such damage. Time is of the essence with respect to the
delivery of such notices.

          (b)  Subject to Section 10.(c), if this Lease is not terminated under
Section 10.(a), then Landlord shall restore the Premises to substantially its
previous condition, except that Landlord shall not be required to rebuild,
repair or replace any part of the partitions, fixtures, additions and other
improvements or personal property required to be covered by tenant's insurance
under Section 9. If the Premises are untenantable, in whole or in part, during
the period beginning on the date such damage occurred and ending on the date of
substantial completion of Landlord's repair or restoration work plus a

<PAGE>
 
reasonable period of time to allow Tenant to install its fixtures and equipment
in the Premises (not to exceed 30 days) (the "REPAIR PERIOD"), then the rent for
                                              -------------                     
such period shall he reduced to such extent as may be fair and reasonable under
the circumstances (even if a Tenant Party caused such damage) and the Term shall
be extended by the number of days in the Repair Period.

          (c)  If the Premises are destroyed or substantially damaged by any
peril not covered by the insurance maintained by Landlord or any Landlord's
Mortgagee (defined below) requires that insurance proceeds be applied to the
indebtedness secured by its Mortgage (defined below) or to the Primary Lease
(defined below) obligations. Landlord may terminate this Lease by delivering
written notice of termination to Tenant within 30 days after such destruction or
damage or such requirement is made known by any such Landlord's Mortgagee, as
applicable, whereupon all rights and obligations hereunder shall cease and
terminate, except for any liabilities of Tenant which accrued before this Lease
is terminated.

     11.  LIABILITY, INDEMNIFICATION, WAIVER OF SUBROGATION AND NEGLIGENCE.
          -----------------------------------------------------------------

          (a)  Subject to Section 11.(b), Tenant shall indemnify, defend, and
hold harmless Landlord, its successors, assigns, agents, employees, contractors,
partners, directors, officers and affiliates (collectively, the "INDEMNIFIED
                                                                 -----------
PARTIES") from and against all fines, suits, losses, costs, liabilities, claims,
-------                                                                         
demands, actions and judgements of every kind or character (1 ) recovered from
or asserted against any of the Indemnified Parties on account of any Loss
(defined below) to the extent that any such Loss arises out of or is caused by a
Tenant Party or any other person entering upon the Premises under or with a
Tenant Party's express or implied invitation or permission, (2) arising from or
out of the occupancy or use by a Tenant Party or arising from or out of any
occurrence in the Premises, howsoever caused, or (3) suffered by, recovered from
or asserted against any of the Indemnified Parties by the employees, agents,
contractors, or invitees of a Tenant Party. However, such indemnification of the
Indemnified Parties by Tenant shall not be applicable if such loss, damage, or
injury is caused by the negligence or willful misconduct of Landlord or any of
its agents, contractors, or employees.  Subject to Section 11.(b) and Section
29, Landlord shall indemnify, defend, and hold harmless Tenant, its successors,
assigns, agents, employees, contractors, partners, directors, officers, and
affiliates from and against all fines, suits, losses, costs, liabilities,
claims, demands, actions and judgements of every kind and character caused by
the negligence or willful misconduct of Landlord or any of its duly authorized
agents or employees.  "LOSS" means any injury to or death of any person or
                       ----                                               
persons or the damage to or theft, destruction, loss, or loss of use of any
property or inconvenience.

          (b)  Landlord and Tenant each waives any claim it might have against
the other for any damage to or theft, destruction, loss, or loss of use of any
property, to the extent the same is insured against under any insurance policy
maintained by it that covers the Premises, Landlord's or Tenant's fixtures,
personal property, leasehold improvements, 

<PAGE>
 
or business, or is required to be insured against by the waiving party under the
terms hereof, REGARDLESS OF WHETHER THE NEGLIGENCE OR FAULT OF THE OTHER PARTY
CAUSED SUCH LOSS; HOWEVER, LANDLORD'S WAIVER SHALL NOT APPLY TO ANY DEDUCTIBLE
AMOUNTS MAINTAINED BY LANDLORD UNDER ITS INSURANCE. Each party shall cause its
insurance carrier to endorse all applicable policies waiving the carrier's
rights of recovery under subrogation or otherwise against the other party.

     12.  USE.
          ----

          (a)  The Premises shall be used only for general office use
(corporate, administrative, and professional), research and development use, and
manufacturing use and for such other lawful purposes as may be incidental
thereto; however, no retail sales may be made from the Premises. Tenant shall
not use the Premises to receive, store or handle any product, material or
merchandise that is explosive or highly inflammable or hazardous, except as
permitted under Section 25. Outside storage is prohibited, except as provided in
Section 29. Subject to Section 4.(a), Tenant shall be solely responsible for
complying with all Laws applicable to the rise, occupancy, and condition of the
Premises. Tenant shall not permit any objectionable or unpleasant odors, smoke,
dust, gas, light, noise or vibrations to emanate from the Premises; nor take any
other action that would constitute a nuisance or would disturb, unreasonably
interfere with, or endanger Landlord or any other person; nor permit the
Premises to be used for any purpose or in any manner that would (1) void the
insurance thereon, (2) increase the insurance risk, or (3) cause the
disallowance of any sprinkler credits. Tenant shall pay to Landlord on demand
any increase in the cost of any insurance on the Premises incurred by Landlord,
which is caused by Tenant's use of the Premises or because Tenant vacates the
Premises.

          (b)  Tenant and its employees and invitees shall have the exclusive
right to use all parking areas associated with the Premises, but Landlord shall
not be responsible for enforcing Tenant's parking rights against third parties.
Landlord, however, will provide Tenant with any documents it requests which
demonstrate Tenant's exclusive right to all parking areas associated with the
Premises.  Landlord shall provide a minimum of 595 parking spaces at the
Premises.

     13.  INSPECTION.  Landlord and Landlord's agents and representatives may
          -----------                                                        
enter the Premises during business hours to inspect the Premises; to make such
repairs as may be required or permitted under this Lease; to perform any
unperformed obligations of Tenant hereunder; and to show the Premises to
prospective purchasers, mortgagees, ground lessors, and (during the last 12
months of the Term) tenants.  If such entrance is not in the case of an
emergency, such entrance shall be prohibited unless Tenant is provided with
reasonable notice (which may be given orally) of such entrance and such entrance
shall be done in such a way as to minimize interference with Tenant's business
to the extent reasonably practicable.  During the last 12 months of the Term,
Landlord may erect a sign on the Premises indicating that the Premises are
available.  Tenant shall notify Landlord in writing of its intention to vacate
the Premises at least 60 days before Tenant will vacate the Premises; such
notice shall specify the date on which Tenant intends to 

<PAGE>
 
vacate the Premises (the "VACATION DATE"). At least 30 days before the Vacation
                          -------------
Date, Tenant shall arrange to meet with Landlord for a joint inspection of the
Premises. After such inspection, the parties will agree on what Tenant must
perform based on Tenant's obligations as set forth in Sections 5 and 16 of this
Lease. If tenant refuses to participate in such inspection, then Landlord may
conduct such inspection and Landlord's determination of the work Tenant is
required to perform before the Vacation Date shall be conclusive. If Tenant
fails to perform such work before the Vacation Date, then Landlord may perform
such work at Tenant's cost. Tenant shall pay all costs incurred by Landlord in
performing such work within ten days after Landlord's request therefor.

     14.  ASSIGNMENT AND SUBLETTING.
          ------------------------- 

          (a)  Tenant shall not, without the prior written consent of Landlord
(which shall not be unreasonably withheld as provided in Section 31), (1)
assign, transfer, or encumber this Lease or any estate or interest herein,
whether directly or by operation of law, (2) permit any other entity to become
Tenant hereunder by merger, consolidation, or other reorganization (except as
provided below), (3) if Tenant is an entity other than a corporation whose stock
is publicly traded, permit the transfer of an ownership interest in Tenant so as
to result in a change in the current control of Tenant, (4) sublet any portion
of the Premises, (5) grant any license, concession, or other right of occupancy
of any portion of the Premises, or (6) permit the use of the Premises by any
parties other than Tenant (any of the events listed in Sections 14.(a)(1)
through 14.(a)(6) being a "TRANSFER").  It shall not be unreasonable for
                           --------                                     
Landlord to withhold its consent to any transferee which intends to use
Hazardous Substances at the Premises.  If Tenant requests Landlord's consent to
a Transfer, then Tenant shall provide Landlord with a written description of all
terms and conditions of the proposed Transfer, copies of the proposed
documentation, and the following information about the proposed transferee: name
and address; reasonably satisfactory information about its business and business
history; its proposed use of the Premises; banking, financial, and other credit
information; and general references sufficient to enable Landlord to determine
the proposed transferee's creditworthiness and character.  Tenant shall
reimburse Landlord for its reasonable attorneys' fees and other expenses
incurred in connection with considering any request for its consent to a
Transfer.  If Landlord consents to a proposed Transfer, then the proposed
transferee shall deliver to Landlord a written agreement whereby it expressly
assumes the Tenant's obligations hereunder (however, any transferee of less than
all of the space in the Premises shall be liable only for obligations under this
Lease that are properly allocable to the space subject to the Transfer, and only
to the extent of the rent it has agreed to pay Tenant therefor).  Landlord's
consent to a Transfer shall not release Tenant from performing its obligations
under this Lease, but rather Tenant and its transferee shall be jointly and
severally liable therefor.  Landlord's consent to any Transfer shall not waive
Landlord's rights as to any subsequent Transfers.  If an Event of Default occurs
while the Premises or any part thereof are subject to a Transfer, then Landlord,
in addition to its other remedies, may collect directly from such transferee all
rents becoming due to Tenant and apply such rents against Tenant's rent
obligations.  Tenant authorizes its transferees to make payments of rent
directly to Landlord upon receipt of notice from Landlord to do so.

<PAGE>
 
          (b)  If no Event of Default exists, all compensation received by
Tenant for or in connection with a Transfer in respect of the interval in
question that exceeds the Base Rent and Operating Expenses allocable to the
portion of the Premises covered thereby for the same interval shall be payable
as follows:

               (1)  first, to Tenant until Tenant has received an amount equal
     to all actual, third-party, out-of-pocket costs incurred by Tenant in
     connection with such Transfer (including brokerage commissions, attorneys'
     fees and expenses, tenant-finish-work, other tenant inducements, and
     advertisement costs); and

               (2)  thereafter, 50% to Landlord and 50% to Tenant.

If an Event of Default exists, all such excess compensation shall be payable to
Landlord.  Tenant shall hold all amounts it receives which are payable to
Landlord in trust and shall deliver all such amounts to Landlord within five
days after Tenant's receipt thereof.

          (c)  Notwithstanding the foregoing, Tenant may Transfer all or part of
its interest in this Lease or all or part of the Premises (a "PERMITTED
                                                              ---------
TRANSFER") to the following types of entities (a "PERMITTED TRANSFEREE") without
                                                  --------------------          
the written consent of Landlord:

               (1)  an affiliate of Tenant;

               (2)  any corporation in which or with which Tenant, or its
     corporate successors or assigns, is merged or consolidated, in accordance
     with applicable statutory provisions governing merger and consolidation of
     corporations, so long as (A) Tenant's obligations hereunder are assumed by
     the corporation surviving such merger or created by such consolidation; and
     (B) the tangible net worth of the surviving or created corporation is not
     less than $100,000,000; or

               (3)  any corporation acquiring all or substantially all of
     Tenant's assets if such corporation's tangible net worth after such
     acquisition is not less than $100,000,000.

Tenant shall promptly notify Landlord of any such Permitted Transfer.

     15.  CONDEMNATION.  If a material portion of the Premises is permanently
          -------------                                                      
taken for any public or quasi-public use by right of eminent domain or private
purchase in lieu thereof (a "TAKING"), such that Tenant is unable to use the
                             ------                                         
Premises for the purpose for which they were leased to Tenant, either party may
terminate this Lease by delivering to the other written notice thereof within 30
days after the Taking, in which case rent shall be abated during the unexpired
portion of the Term, effective on the date of such Taking.  If (a) less than a
material portion of the Premises are subject to a Taking or (b) a material
portion of the Premises are subject to a Taking, but the Taking does not prevent
or 

<PAGE>
 
materially interfere with Tenant's use of the Premises for the purpose for which
they were leased to Tenant, then neither party may terminate this Lease, but the
rent payable during the unexpired portion of the Term shall be reduced to such
extent as may be fair and reasonable under the circumstances. All compensation
awarded for any Taking shall be the property of Landlord and Tenant assigns any
interest it may have in any such award to Landlord; however, Landlord shall have
no interest in any award made to Tenant for loss of business or goodwill, for
the taking of Tenant's trade fixtures, or for relocation expenses, if a separate
award for such items is made to Tenant.

     16.  SURRENDER OF PREMISES, HOLDING OVER.
          ------------------------------------

          (a)  No act by Landlord shall be an acceptance of a surrender of the
Premises, and no agreement to accept a surrender of the Premises shall be valid
unless it is in writing and signed by Landlord. At the end of the Term or the
termination of Tenant's right to possess the Premises, Tenant shall (1) deliver
to Landlord the Premises with all improvements located thereon in good repair
and condition, reasonable wear and tear (subject however to Tenant's maintenance
obligations) excepted, and with the HVAC System and hot water equipment, light
and light fixtures (including ballasts), and overhead doors and related
equipment in good working order, (2) deliver to Landlord all keys to the
Premises, and (3) remove all signage placed on the Premises by or at Tenant's
request. All fixtures, alterations, additions, and improvements (whether
temporary or permanent) shall be Landlord's property and shall remain on the
Premises except as provided below. Tenant may remove all trade fixtures
(including the clean room, ultra-pure gas farm area, and ultrapure water farm
area), furniture, and personal property placed in the Premises by Tenant (but
Tenant shall not remove any such item which was paid for, in whole or in part,
by Landlord). Additionally, if the Term has not been cancelled in accordance
with Section 27 hereof, Tenant shall remove such alterations, additions,
improvements, fixtures, equipment, wiring, cabling, furniture, and other
property as Landlord may request, provided such request is made within two
months after the end of the Term. All items not so removed shall, at the option
of Landlord, be deemed abandoned by Tenant and may be appropriated, sold,
stored, destroyed, or otherwise disposed of by Landlord without notice to Tenant
and without any obligation to account for such items and Tenant shall pay for
the costs incurred by Landlord in connection therewith. All work required of
Tenant under this Section 16.(a) shall be coordinated with Landlord and be done
in a good and workmanlike manner, in accordance with all Laws, and so as not to
damage the Premises. Tenant shall, at its expense, repair all damage caused by
any work performed by Tenant under this Section 16.(a).

          (b)  If Tenant falls to vacate the Premises at the end of the Term,
then Tenant shall be a Tenant at will and Tenant shall pay, in addition to the
other rent due hereunder, a daily base rental equal to 150% of the daily Base
Rent payable during the last month of the Term, even if Landlord consents to
such holdover, unless Landlord agrees otherwise in writing. Additionally Tenant
shall defend, indemnify, and hold harmless Landlord from any damage, liability
and expense (including attorneys' fees and expenses) incurred because of such
holding over. No payments of money by Tenant to Landlord 

<PAGE>
 
after the Term shall reinstate, continue or extend the Term, and no extension of
the Term shall be valid unless it is in writing and signed by Landlord and
Tenant.

     17.  QUIET ENJOYMENT.  Provided Tenant has fully performed its obligations
          ---------------                                                      
under this Lease, Tenant shall peaceably and quietly hold and enjoy the Premises
for the Term, without hindrance from Landlord or any party claiming by, through,
or under Landlord, but not otherwise.

     18.  EVENTS OF DEFAULT. Each of the following events shall constitute an
          -----------------                                                
"EVENTS OF DEFAULT" under this Lease:
 -----------------                   

          (a) Tenant's failure to pay rent when due and the continuance of such
failure for a period of ten days after Landlord has delivered to Tenant written
notice thereof.

          (b) The filing of a petition by or against Tenant or any guarantor of
Tenant's obligations hereunder (1) in any bankruptcy or other insolvency
proceeding; (2) seeking any relief under any debtor relief Law; (3) for the
appointment of a liquidator, receiver, trustee, custodian, or similar official
for all or substantially all of Tenant's property or for Tenant's interest in
this Lease; or (4) for reorganization or modification of Tenant's capital
structure (however, if any such petition is filed against Tenant, then the
filing of such petition shall not constitute an Event of Default, unless it is
not dismissed within 120 days after the filing thereof).

          (c) Tenant fails to discharge any lien placed upon the Premises in
violation of Section 22 within 20 days after Tenant has received written notice
of any such lien or encumbrance is filed against the Premises.

          (d) Tenant fails to comply with any term, provision, or covenant of
this Lease (other than those listed in this Section 18) and such failure
continues for 30 days after written notice thereof to Tenant; however, if such
failure cannot be cured within such 30-day period and Tenant begins to cure such
failure within such 30-day period and thereafter diligently pursues such cure to
completion, such failure shall not be an Event of Default unless it is not cured
within 180 day after Landlord initially delivered to Tenant written notice of
the failure in question.  Landlord may not terminate this Lease or terminate
Tenant's right to possess the Premises because of a default under this Section
18.(d) unless such default is material.

     19.  REMEDIES.
          --------

     (a)  Upon any Event of Default, Landlord may, in addition to all other
rights and remedies afforded Landlord hereunder or by Law, take any of the
following actions:

<PAGE>
 
               (1)  Terminate this Lease by giving Tenant written notice
     thereof, in which event, Tenant shall pay to Landlord the sum of (A) all
     rent accrued hereunder through the date of termination, (B) all amounts due
     under Section 19.(b), and (C) an amount equal to (i) the total rent that
     Tenant would have been required to pay for the remainder of the Term
     discounted to present value at a per annum rate equal to the rate of
     interest set forth for 26-week U.S. governmental bills sold at a discount
     from face value in units of $10,000 to $1,000,000 as published on the date
     this Lease is terminated by The Wall Street Journal, Southwest Edition, in
     its listing of "Money Rates" under the heading "Treasury Bills" (or, if no
     such rate is published, the "Discount Rate" as published on such date under
     the by "Money Rates"" listing), minus (ii) the then present fair rental
     value of the Premises for such period, similarly discounted; or

               (2)  Terminate Tenant's right to possess the Premises without
     terminating this Lease by giving written notice thereof to Tenant, in which
     event Tenant shall pay to Landlord (A) all rent and other amounts accrued
     hereunder to the date of termination of possession, (B) all amounts due
     from time to time under Section 19.(b), and (C) all rent and other sums
     required hereunder to be paid by Tenant during the remainder of the Term,
     diminished by any net sums thereafter received by Landlord through
     reletting the Premises during such period.  Landlord shall use reasonable
     efforts to relet the Premises on such terms and conditions as Landlord may
     determine (including a term different than the Term concessions, and
     alterations to, and improvement of, the Premises); however, Landlord shall
     not be obligated to relet the Premises before leasing other portions of the
     business park of which the Building is a part.  Landlord shall not be
     liable for, nor shall Tenant's obligations hereunder be diminished because
     of, Landlord's failure to relet the Premises or to collect rent due for
     such reletting.  Tenant shall not be entitled to the excess of any
     consideration obtained by reletting over the rent due hereunder.  Reentry
     by Landlord in the Premises shall not affect Tenant's obligations hereunder
     for the unexpired Term; rather, Landlord may, from time to time, bring
     action against Tenant to collect amounts due by Tenant, without the
     necessity of Landlord's waiting until the expiration of the Term.  Unless
     Landlord delivers written notice to Tenant expressly stating that it has
     elected to terminate this Lease, all actions taken by Landlord to exclude
     or dispossess Tenant of the Premises shall be deemed to be taken under this
     Section 19.(a)(2). If Landlord elects to proceed under this Section
     19.(a)(2), it may at any time elect to terminate this Lease under Section
     19.(a)(1).

Additionally Landlord may perform Tenant's unperformed obligations hereunder
and, without notice, Landlord may alter locks or other security devices at the
Premises to deprive Tenant of access thereto, and Landlord shall not be required
to provide a new key or right of access to Tenant.

               (b)  Tenant shall pay to Landlord all costs incurred by Landlord
(including court costs and reasonable attorneys' fees and expenses) in (1)
obtaining possession of the Premises, (2) removing and storing Tenant's or any
other occupant's

<PAGE>
 
property, (3) repairing, restoring, altering, remodelling, or otherwise putting
the Premises into condition acceptable to a new tenant, (4) if Tenant is
dispossessed of the Premises and this Lease is not terminated, reletting all or
any part of the Premises (including brokerage commissions, cost of tenant finish
work, and other costs incidental to such reletting), (5) performing Tenant's
obligations which Tenant failed to perform, and (6) enforcing, or advising
Landlord of, its rights, remedies, and recourses. Landlord's acceptance of rent
following an Event of Default shall not waive Landlord's rights regarding such
Event of Default. Landlord's receipt of rent with knowledge of any default by
Tenant hereunder shall not be a waiver of such default, and no waiver by
Landlord of any provision of this Lease shall be deemed to have been made unless
set forth in writing and signed by Landlord. No waiver by Landlord of any
violation or breach of any of the terms contained herein shall waive Landlord's
rights regarding any future violation of such term or violation of any other
term. If Landlord repossesses the Premises pursuant to the authority herein
granted, then Landlord shall have the right to (A) keep in place and use or (B)
remove and store, at Tenant's expense, all of the furniture, fixtures, equipment
and other property in the Premises, including that which is owned by or leased
to Tenant at all times before any foreclosure thereon by Landlord or
repossession thereof by any lessor thereof or third party having a lien thereon.
Landlord may relinquish possession of all or any portion of such furniture,
fixtures, equipment and other property to any person (a "CLAIMANT") who presents
                                                         --------
to Landlord a copy of any instrument represented by Claimant to have been
executed by Tenant (or any predecessor of Tenant) granting Claimant the right
under various circumstances to take possession of such furniture, fixtures,
equipment or other property, without the necessity on the part of Landlord to
inquire into the authenticity or legality of the instrument. Landlord may, at
its option and without prejudice to or waiver of any rights it may have, (i)
escort Tenant to the Premises to retrieve any personal belongings of Tenant
and/or its employees or (ii) obtain a list from Tenant of the personal property
of Tenant and/or its employees, and make such property available to Tenant
and/or Tenant's employees; however, Tenant first shall pay in cash all costs and
estimated expenses to be incurred in connection with the removal of such
property and making it available. The rights of Landlord herein stated are in
addition to any and all other rights that Landlord has or may hereafter have at
Law or in equity, and Tenant agrees that the rights herein granted Landlord are
commercially reasonable.

     20.  LANDLORD'S DEFAULT.  Except as provided below in this Section 20,
          ------------------                                               
Tenant's exclusive remedy for Landlord's failure to perform its obligations
under this Lease shall be limited to damages, injunctive relief, or specific
performance; in each case, Landlord's liability or obligations with respect to
any such remedy shall be limited as provided in the last paragraph of this
Section 20.  Landlord shall be in default under this Lease if Landlord fails to
perform any of its obligations hereunder within 30 days after written notice
from Tenant specifying such failure; however, if such failure cannot reasonably
be cured within such 30-day period, but Landlord commences to cure such failure
within such 30-day period, thereafter diligently pursues the curing thereof to
completion, and such failure is cured within 180 days after Tenant first
delivered to Landlord written notice thereof, then Landlord shall not be in
default hereunder or liable for damages therefor.  Unless Landlord falls to so
cure such default after such notice,

<PAGE>
 
Tenant shall not have any remedy or cause of action by reason thereof. If
Landlord fails to perform its obligations within the time periods specified in
the previous sentences of this Section 20, and such failure adversely affects
Tenant's use of the Premises, then Tenant may perform such obligations and
Landlord shall reimburse Tenant all actual third-party, out-of-pocket costs
incurred by Tenant in connection with performing such obligations (other than
those which would constitute an Operating Expense had Landlord performed such
work, in which case, Landlord shall not be obligated to reimburse Tenant
therefor) within 30 days after Tenant delivers to Landlord written demand
therefor, accompanied by invoices substantiating Tenant's claim. If Landlord
fails to pay such amount within such 30-day period, Tenant may offset against
its obligation to pay Base Rent such costs, unless Landlord is in good faith
disputing such claim, in which case, Tenant may offset the amount of such claim
which is not in dispute. If Landlord is disputing Tenant's claim for any amounts
due under this Section 20, Tenant may initiate the arbitration proceedings
provided herein by delivering to Landlord written notice thereof (an
"ARBITRATION NOTICE"). If Tenant delivers an Arbitration Notice, Landlord and
 ------------------
Tenant shall, within five days after the delivery of such notice, jointly
appoint an arbitrator with at least five-years' real estate experience who has
not performed substantial work for either party during the previous five-year
period. If the parties cannot agree upon such arbitrator within such five-day
period, then either Landlord or Tenant may request that the Dallas office of the
American Arbitration Association (the "AAA") appoint an arbitrator meeting the
                                       ---
qualifications specified in the previous sentence. The arbitrator selected by
the AAA shall be binding on Landlord and Tenant. The arbitrator shall thereafter
resolve the dispute within 15 days after his appointment, based on evidence
submitted to him by Landlord and Tenant and such other evidence as he may
request. However, the arbitrator shall conduct such proceedings as expeditiously
and inexpensively as possible and, in connection therewith, may establish such
rules for the proceedings as he deems necessary, which will be binding on all
parties to the arbitration proceeding. Accordingly, the arbitrator may (1)
dispense with any formal rules of evidence and allow hearsay testimony so as to
limit the number of witnesses required, (2) limit the time for presentation of
any party's case as well as the amount of information or number of witnesses to
be presented in connection with any hearing, and (3) impose any other rules
which the arbitrator believes are appropriate to resolve the dispute as quickly
and inexpensively as possible. The arbitrator's decision shall be binding on the
parties. The non-prevailing party shall pay all costs of the arbitration,
including all costs incurred by the prevailing party (including attorneys' fees
and expenses).

           Tenant's right to perform the work under this Section 20 is subject
to the following conditions: (A) all such work shall be performed in a good and
workmanlike manner, in accordance with Law, and in a manner so as not to affect
any existing warranties with respect to the Building's Structure; (B) all such
work shall be performed in a manner so as not to alter any portion of the
Building's Structure (except for necessary alterations required to comply with
Law), unless Landlord otherwise consents thereto (if such work would alter any
portion of the Building's Structure, all such work shall be performed in
accordance with plans and specifications approved by Landlord [which approval
shall not be unreasonably withheld], whose approval shall be deemed

<PAGE>
 
 given if Landlord fails to disapprove any submitted plans and specifications
 within ten business days after their submission to Landlord); (C) all such work
 shall be performed by contractors which maintain commercial liability insurance
 on an occurrence basis in an amount not less than $1,000,000 per occurrence
 naming Landlord as an additional insured; and (D) Tenant delivers to Landlord
 "as-built" plans of the work performed by Tenant. If Landlord defaults in its
 obligations under Section 4.(b) (after the expiration of any applicable cure
 periods) and Tenant performs and pays for such obligations, there shall be
 excluded from the calculation of Operating Expense the management fees payable
 during the period such default existed.

           Any recourse against Landlord under this Lease shall be limited to
 Landlord's interest in the Premises and rents derived therefrom, and neither
 Landlord nor Landlord's owners shall have any personal liability therefor.
 Nothing in this Lease shall preclude Tenant from seeking injunctive relief. The
 obligations of Landlord under this Lease will be binding upon Landlord only for
 obligations accruing during the period of its ownership of the Premises and not
 thereafter.

     21.   MORTGAGES.
           ---------

            (a)  Subject to the last sentence of this Section 21.(a), this Lease
 shall be subordinate to any deed of trust, mortgage or other security
 instrument (a "MORTGAGE"), and any ground lease, master lease, or primary lease
                --------                                                        
 (a "PRIMARY LEASE") that now or hereafter covers any portion of the Premises
     -------------                                                           
 (the mortgagee under any Mortgage or the lessor under any Primary Lease is
 referred to herein as "LANDLORD'S MORTGAGEE") and to increases, renewals,
                        --------------------                              
 modifications, consolidations, replacements, and extensions thereof.  However,
 any Landlord's Mortgagee may elect to subordinate its Mortgage or Primary Lease
 (as the case may be) to this Lease by delivering written notice thereof to
 Tenant.  Except as provided in the last sentence of this Section 21.(a), no
 further instrument shall be required to effect such subordination; however,
 Tenant shall from time to time within ten days after request therefor, execute
 any instruments that may be required by any Landlord's Mortgagee to evidence
 the subordination of this Lease to any such Mortgage or Primary Lease.
 Landlord hereby represents and warrants to Tenant that the Premises is not
 currently encumbered by a Mortgage or a Primary Lease.  As a condition to the
 subordination of this Lease to a Mortgage or a Primary Lease, the Landlord's
 Mortgagee, shall execute and deliver to Tenant a commercially reasonable non-
 disturbance, subordination, and attornment agreement.

            (b)  Tenant shall attorn to any party succeeding to Landlord's
 interest in the Premises, whether by purchase, foreclosure, deed in lieu of
 foreclosure, power of sale, termination of lease, or otherwise, upon such
 party's request, and shall execute such agreements confirming such attornment
 as such party may reasonably request. Tenant shall not seek to enforce any
 remedy it may have for any default on the part of Landlord without first giving
 written notice by certified mail, return receipt requested, specifying the
 default in reasonable detail to any Landlord's Mortgagee whose address has been

<PAGE>
 
given to Tenant, and affording such Landlord's Mortgagee a reasonable
opportunity to perform Landlord's obligations hereunder.

            (c)  Notwithstanding any such attornment or subordination of a
Mortgage or Primary Lease to this Lease, the Landlord's Mortgagee shall not be
liable for any acts of any previous landlord (but the Landlord's Mortgagee shall
be subject to the offset rights of Tenant under Section 20) and shall not be
bound by any amendment to which it did not consent in writing nor any payment of
rent made more than one month in advance.

     22.  ENCUMBRANCES. Tenant has no authority, express or implied, to create
          ------------                                                        
or place any lien or encumbrance of any kind or nature whatsoever upon, or in
any manner to bind Landlord's property or the interest of Landlord or Tenant in
the Premises or to charge the rent for any claim in favor of any person dealing
with Tenant, including those who may furnish materials or perform labor for any
construction or repairs. Tenant shall pay or cause to be paid all sums due for
any labor performed or materials furnished in connection with any work performed
on the Premises by or at the request of Tenant. Tenant shall give Landlord
immediate written notice of the placing of any lien or encumbrance against the
Premises.

     23.  MISCELLANEOUS.
          -------------

          (a)  Words of any gender used in this Lease shall include any other
gender, and words in the singular shall include the plural, unless the context
otherwise requires.  The captions inserted in this Lease are for convenience
only and in no way affect the interpretation of this Lease.  The following terms
shall have the following meanings:  "LAWS" shall mean all federal, state, and
                                     ----                                    
local laws, rules, and regulations; all court orders, governmental directives,
and governmental orders; and all restrictive covenants affecting the Property,
and "LAW" shall mean any of the foregoing; "AFFILIATE" shall mean any person or
     ---                                    ---------                          
entity which, directly or indirectly, controls, is controlled by, or is under
common control with the party in question; "TENANT PARTY" shall include Tenant,
                                            ------------                       
any assignees claiming by, through, or under Tenant, any subtenants claiming by,
through, or under Tenant, and any of their respective agents, contractors,
employees, and invitees; and "INCLUDING" shall mean including, without
                              ---------                               
limitation.  The normal rule of construction that any ambiguities be resolved
against the drafting party shall not apply to the interpretation of this Lease
or any exhibits or amendments hereto.

          (b)  Landlord may transfer and assign, in whole or in part, its rights
and obligations in the Building and property that are the subject to this Lease,
in which case Landlord shall have no liability hereunder for any obligations
arising from and after the transfer or assignment and Tenant shall attorn to
such transferee, provided that the transferee assumes the obligations of
Landlord hereunder in writing (including the return of the Security Deposit).
Each party shall furnish to the other, promptly upon demand, a corporate
resolution, proof of due authorization by partners, or other appropriate
documentation evidencing the due authorization of such party to enter into this
Lease.

<PAGE>
 
           (c)  Except for the payment of rent and the maintenance of insurance,
 whenever a period of time is herein prescribed for action to be taken by
 Landlord or Tenant, such party shall not be liable or responsible for, and
 there shall be excluded from the computation for any such period of time, any
 delays due to strikes, riots, acts of God, shortages of labor or materials,
 war, Laws or any other causes of any kind whatsoever which are beyond the
 control of the party in question.

           (d)  Tenant shall, from time to time, within 20 days after request of
 Landlord, deliver to Landlord, or Landlord's designee, a certificate of
 occupancy for the Premises, financial statements for itself and any guarantor
 of its obligations hereunder, evidence reasonably satisfactory to Landlord that
 Tenant has performed its obligations under this Lease (including evidence of
 the payment of the Security Deposit), and an estoppel certificate stating that
 this Lease is in full effect, the date to which rent has been paid, the
 unexpired Term and such other factual matters pertaining to this Lease as may
 be reasonably requested by Landlord.  Tenant's obligation to furnish the above-
 described items in a timely fashion is a material inducement for Landlord's
 execution of this Lease.

           (e)  This Lease constitutes the entire agreement of the Landlord
 (including all exhibits attached hereto which are incorporated herein) and
 Tenant with respect to the subject matter of this Lease, and contains all of
 the covenants and agreements of Landlord and Tenant with respect thereto.
 Landlord and Tenant each acknowledge that no representations, inducements,
 promises or agreements, oral or written, have been made by Landlord or Tenant,
 or anyone acting on behalf of Landlord or Tenant, which are not contained
 herein, and any prior agreements, promises, negotiations, or representations
 riot expressly set forth in this Lease are of no effect.  This Lease may not be
 altered, changed or amended except by an instrument in writing signed by both
 parties hereto.

           (f)  All obligations of either party hereunder not fully performed by
 the end of the Term shall survive, including all payment obligations of either
 party and all of Tenant's obligations concerning the condition and repair of
 the Premises.  After Tenant has satisfied its obligations under the Lease,
 Landlord shall promptly return the Security Deposit with interest to the Tenant
 as specified in Section 2.(b).

           (g)  If any provision of this Lease is illegal, invalid or
 unenforceable, then the remainder of this Lease shall not be affected thereby,
 and in lieu of each such provision, there shall be added, as a part of this
 Lease, a provision as similar in terms to such illegal, invalid or
 unenforceable clause or provision as may be possible and be legal, valid and
 enforceable.

           (h)  All references in this Lease to "the date hereof" or similar
 references shall be deemed to refer to the last date, in point of time, on
 which all parties hereto have executed this Lease.

           (i)  Landlord and Tenant each warrant to the other that it has not
 dealt with any broker or agent in connection with this Lease, other than
 Trammell Crow Dallas

<PAGE>
 
 Industrial, Ltd. and CB Commercial Real Estate Group, Inc., whose commissions
 shall be paid by Landlord. Tenant and Landlord shall each indemnify the other
 against all costs, attorneys' fees, and other liabilities for commissions or
 other compensation claimed by any other broker or agent claiming the same by,
 through, or under the indemnifying party.

          (j)  If and when included within the term "Tenant", as used in this
instrument, there is more than one person, firm or corporation, all shall
jointly arrange among themselves for their joint execution of a notice
specifying an individual at a specific address within the continental United
States for the receipt of notices and payments to Tenant.  All parties included
within the terms "Landlord" and "Tenant", respectively, shall be bound by
notices given in accordance with the provisions of Section 24 to the same effect
as if each had received such notice,

          (k)  The terms and conditions of this Lease are confidential and
neither Landlord nor Tenant shall disclose the terms of this Lease to any third
party except as may be required by Law or to enforce its rights hereunder.

          (l)  Each of Landlord and Tenant shall pay interest on all past-due
amounts owing from it to the other from the date due until paid at the maximum
lawful rate.  In no event, however, shall the charges permitted under this
Section 23.(1) or elsewhere in this Lease, to the extent they are considered to
he interest under applicable Law, exceed the maximum lawful rate of interest.

     24.  NOTICES.   Each provision of this instrument or of any applicable Laws
          -------                                                             
and other requirements with reference to the sending, mailing or delivering of
notice or the making of any payment hereunder shall be deemed to be complied
with when and if the following steps are taken:

          (a)  All rent shall be payable to Landlord at the address for Landlord
set forth below or at such other address as Landlord may specify from time to
time by written notice delivered in accordance herewith.  Tenant's obligation to
pay rent shall not be deemed satisfied until such rent has been actually
received by Landlord.

          (b)  All payments required to be made by Landlord to Tenant hereunder
shall be payable to Tenant at the address set forth below, or at such other
address within the continental United States as Tenant may specify from time to
time by written notice delivered in accordance herewith.

          (c)  Any written notice or document required or permitted to be
delivered hereunder shall be deemed to be delivered upon the earlier to occur of
(1) tender of delivery (in the case of a hand-delivered notice), (2) deposit in
the United States Mail, postage prepaid, Certified Mail, or (3) receipt by
facsimile transmission, in each case, addressed to the parties hereto at the
respective addresses set out below, or at such other address as they have
theretofore specified by written notice delivered in accordance

<PAGE>
 
herewith. If Landlord has attempted to deliver notice to Tenant at Tenant's
address reflected on Landlord's books but such notice was returned or acceptance
thereof was refused, then Landlord may post such notice in or on the Premises,
which notice shall be deemed delivered to Tenant upon the posting thereof

    25.  HAZARDOUS WASTE.  The term "HAZARDOUS SUBSTANCES", as used in this
         ---------------             --------------------                  
Lease shall mean pollutants, contaminants, toxic or hazardous wastes, or any
other substances, the removal of which is required or the use of which is
restricted, prohibited or penalized by any "ENVIRONMENTAL LAW" which term shall
                                            -----------------                  
mean any Law relating to health, pollution, or protection of the environment.
Tenant hereby agrees that (a) no activity will be conducted on the Premises that
will produce any Hazardous Substances, except for such activities that are part
of the ordinary course of Tenant's business activities (the "PERMITTED
                                                             ---------
ACTIVITIES") provided such Permitted Activities are conducted in accordance with
----------                                                                      
all Environmental Laws; (b) the Premises will not be used in any manner for the
storage of any Hazardous Substances except for storage of such materials that
are used in the ordinary course of Tenant's business (the "PERMITTED MATERIALS")
                                                           -------------------  
provided such Permitted Materials are properly stored in a manner and location
satisfying all Environmental Laws; (c) no portion of the Premises will be used
as a landfill or a dump; (d) Tenant will not install any underground tanks of
any type; (e) Tenant will not allow any surface or subsurface conditions to
exist or come into existence that constitute, or with the passage of time may
constitute a public or private nuisance; and (f) Tenant will not permit any
Hazardous Substances to be brought onto the Premises, except for the Permitted
Materials, and if so brought or found located thereon, the same shall be
immediately removed by Tenant, with proper disposal, and all required cleanup
procedures shall be diligently undertaken pursuant to all Environmental Laws.
If at any time during or after the Term, the Premises are found to be so
contaminated or subject to such conditions, Tenant shall defend, indemnify and
hold Landlord harmless from all claims, demands, actions, liabilities, costs,
expenses, damages and obligations of any nature arising from or as a result of
the use of the Premises by a Tenant Party.  Tenant will maintain on the Premises
a list of all materials stored at the Premises for which a material safety data
sheet (an "MSDS") was issued by the producers or manufacturers thereof, together
           ----                                                                 
with copies of the MSDS's for such materials, and shall deliver such list and
MSDS copies to Landlord upon Landlord's request therefor.  Except for Landlord
Hazardous Substances (defined below), Tenant shall remove all Permitted
Materials and other Hazardous Substances from the Premises in a manner
acceptable to Landlord before the earlier of the date Tenant vacates the
Premises and the date Tenant's right to possess the Premises ends.  Landlord may
enter the Premises and conduct environmental inspections and tests therein as it
may require from time to time, provided that Landlord shall use reasonable
efforts to minimize the interference with Tenant's business.  Such inspections
and tests shall be conducted at Landlord's expense, unless they reveal the
presence of Hazardous Substances (other than Permitted Materials and Landlord
Hazardous Substances) or that Tenant has not complied with the requirements set
forth in this Section 25, in which case Tenant shall reimburse Landlord for the
cost thereof within ten days after Landlord's request therefor.

<PAGE>
 
         Notwithstanding the foregoing, within 30 days after Tenant vacates the
Premises, Tenant shall, at its expense, deliver to Landlord a Phase 1
environmental report prepared by a reputable environmental engineer reasonably
acceptable to Landlord (and, if such report indicates the need for a Phase 11
report or other reports, such additional reports prepared by such an engineer)
indicating that no Hazardous Substances exist on the Property.  If any such
report reveals that any hazardous Substances (other than Landlord Hazardous
Substances) exist on the Property, Tenant shall remove all such substances in a
manner acceptable to Landlord in its sole discretion.

         Landlord shall be responsible for all Hazardous Substances located on
the Property on the Commencement Date which were not placed on the property by a
Tenant Party and all Hazardous Substances placed on the Premises by Landlord or
its agents, contractors or employees (collectively, "LANDLORD HAZARDOUS
                                                     ------------------
SUBSTANCES").  Additionally, if Tenant is prohibited from using the Premises for
----------                                                                      
three consecutive business days because of the presence of any Landlord
Hazardous Substances which could reasonably be expected to pose a health risk to
the occupants of the Premises and Tenant ceases using the Premises as a result
thereof, then Tenant's obligation to pay Base Rent and Operating Expenses shall
be abated until such time as Tenant may reasonably use the Premises.

     26. LANDLORD'S LIEN. Landlord hereby waives its statutory landlord's lien
         ---------------                                                    
against Tenant's property in the Premises.

     27. TENANT'S CANCELLATION RIGHT. Provided that no Event of Default exists
         ---------------------------                                        
when Tenant delivers the Cancellation Notice or on the cancellation date,
Tenant may cancel this Lease effective as of the last day of any calendar month
after the 60th full calendar month of the Term by delivering to Landlord at
least nine months before the cancellation date (a) written notice thereof and
(b) the Cancellation Fee (defined below).  The "CANCELLATION FEE" shall equal
                                                ----------------             
the sum of $1,866,000 plus the amount that would be outstanding on a
hypothetical loan on the cancellation date assuming (1) an original principal
balance equal to the Leasing Costs (defined below), (2) an interest rate of 11
% per annum, (3) the loan is payable in equal monthly installments of principal
and interest, beginning on the first day of the first full calendar month of
the Term and ending on the first day of the last scheduled month of the Term
(assuming the Lease had not been terminated), and (4) all payments were made
before the cancellation date.  The term "LEASING COSTS" shall mean all costs
                                         -------------                      
incurred by Landlord in leasing the space to Tenant for leasing commissions and
attorneys' fees and expenses.  As a condition to the effectiveness of Tenant's
cancellation right, Tenant shall pay to Landlord prior to the cancellation date
any past-due amounts then outstanding under the Lease.  If Tenant fails timely
to deliver the Cancellation Fee or the cancellation notice or is otherwise
unable to exercise this cancellation option, then Tenant's right to cancel this
Lease under this Section 27 shall expire; time is of the essence with respect
thereto.

<PAGE>
 
      28.  SECURITY SERVICE. Landlord shall have no obligation whatsoever to
           ----------------                                               
 provide security services to the Premises; however, Tenant may provide such
 services at its sole expense, in which case, Tenant shall defend, indemnify,
 and hold harmless Landlord from any liability arising in connection with the
 provision of such security service.

      29.  TENANT'S OPERATIONAL AREAS. In connection with its use of the
           --------------------------                                  
 Premises and subject to compliance with Section 25 hereof, Tenant may install,
 operate and maintain an ultrapure gas farm area, an ultra-pure water farm area,
 a barrel storage/hazardous waste area, and mechanical area ("TENANT'S
                                                              --------
 OPERATIONAL AREAS") on the exterior of the Premises at a location reasonably
 -----------------                                                           
 acceptable to Landlord, provided that the installation, maintenance, use, and
 operation thereof complies with all Laws, and Tenant receives all approvals,
 consents, and permits required under Law before the installation, maintenance,
 use and operation thereof.  Before beginning the installation of any such item,
 Tenant shall deliver to Landlord final plans and specifications therefor
 prepared by an engineer reasonably approved by Landlord setting forth in detail
 the design, location, size and method of installation for Landlord's review and
 approval (which shall not be unreasonably withheld), together with evidence
 reasonably satisfactory to Landlord that all Laws have been satisfied.
 Landlord's approval of any such plans and specifications shall not constitute a
 representation or warranty by Landlord that such plans and specifications
 comply with Law; such compliance shall be the sole responsibility of Tenant.
 Upon approval of the plans and specifications therefor and the size and
 location thereof, Tenant may install the Tenant Operational Areas provided that
 such work is coordinated with Landlord and is performed in a good and
 workmanlike manner, in accordance with Law and the plans and specifications
 therefor and in a manner so as not to damage the Premises; thereafter, Tenant
 shall use, maintain, and operate the Tenant Operational Areas in a good, clean,
 and safe condition and in accordance with all Laws.  Tenant shall repair all
 damage caused by the installation, use, maintenance, operation, or removal of
 the Tenant Operational Areas and, upon its removal, restore the portions of the
 Premises where they were located to their condition immediately before the
 installation thereof.  If Tenant fails to do so within 30 days after Landlord's
 request, Landlord may perform such work and Tenant shall pay to Landlord all
 reasonable costs incurred in connection therewith within 30 days after
 Landlord's written request therefor.  Tenant shall immediately remove from the
 area surrounding the Tenant Operational Areas any spills or other leaks of
 fluid or Hazardous Substances.  Additionally, Tenant shall ensure that the
 Tenant Operational Areas are properly exhausted at all times so no odors
 emanate therefrom.  The Tenant Operational Areas shall be installed, used,
 maintained, operated, and removed at Tenant's risk and expense and Tenant shall
 maintain insurance in respect thereof reasonably satisfactory to Landlord,
 listing Landlord, as an additional insured.  IT IS THE INTENTION OF THE PARTIES
 THAT TENANT BEAR ALL RISKS RELATING TO THE INSTALLATION, USE, MAINTENANCE,
 OPERATION, AND REMOVAL OF THE TENANT OPERATIONAL AREAS; THEREFORE, TENANT SHALL
 DEFEND, INDEMNIFY, AND HOLD HARMLESS LANDLORD, ITS AGENTS, AND THEIR RESPECTIVE
 AFFILIATES FROM ALL LOSSES, CLAIMS, COSTS, AND LIABILITIES ARISING IN
 CONNECTION WITH OR RELATING TO THE INSTALLATION, MAINTENANCE, USE, OPERATION,
 AND REMOVAL OF THE TENANT OPERATIONAL

<PAGE>
 
 AREAS, INCLUDING, WITHOUT LIMITATION, THAT ARISING FROM LANDLORD'S NEGLIGENCE
 (OTHER THAN ITS SOLE OR GROSS NEGLIGENCE), SPECIFICALLY INCLUDING SITUATIONS
 WHERE LANDLORD OR ITS CONTRACTORS, AGENTS, OR EMPLOYEES ARE JOINTLY,
 CONCURRENTLY OR COMPARATIVELY NEGLIGENT WITH A TENANT PARTY (UNLESS THE ACTS OF
 LANDLORD OR ITS AGENTS, CONTRACTORS, OR EMPLOYEES ARE FOUND TO HAVE CONTRIBUTED
 TO MORE THAN 30% OF THE LIABILITY IN QUESTION).

     30.  LANDLORD'S BANKRUPTCY.  In the event that the obligations of Landlord
          ---------------------                                               
under this Lease are not performed during the pendency of a bankruptcy or
insolvency proceeding involving the Landlord as the debtor, or following the
rejection of this Lease by Landlord in accordance with Section 365 of the United
States Bankruptcy Code, then notwithstanding any provision of this Lease to the
contrary, Tenant shall have the right to set off against rents next due and
owing under this Lease (a) any and all damages caused by such non-performance of
Landlord's obligations under this Lease by Landlord, debtor-in-possession, or
the bankruptcy trustee, and (b) any and all damages caused by the non-
performance of Landlord's obligations under this Lease following any rejection
of this Lease by Landlord in accordance with Section 365 of the United States
Bankruptcy Code.

     31.  CONSENT. If either party's consent is required hereunder for the other
          -------                                                             
party to take any action, then the party whose consent is required (the
"CONSENTING PARTY") shall not unreasonably withhold such consent, regardless of
 ----------------                                                              
whether the provision addressing such matter specifically states that Landlord's
consent is not to be unreasonably withheld.  If the Consenting Party fails to
respond to a request for its consent or approval within ten business days after
it has received a written request therefor, together with all information
reasonably necessary for it to make an informed decision regarding the matter in
question, then such party's consent shall be deemed granted.  If the Consenting
Party refuses to give its consent to the matter in question, then it shall
specify in reasonable detail the reasons therefor.

     32.  COUNTERPARTS; FACSIMILE SIGNATURES. Landlord and Tenant may execute
          ----------------------------------                               
this Lease in any number of counterparts with the same effect as if they had
signed the same document.  Execution of this Lease may be effected by facsimile
transmission.

     33.  EMERGENCY REPAIRS BY TENANT.  Tenant may make repairs to the
          ---------------------------                                
Building's Structure in case of an emergency to avoid imminent damage to
property or injury to persons, without Landlord's prior written consent;
however, any such work shall be limited to the extent necessary to alleviate
such imminent risk of damage and injury and is done in accordance with Law and
in a good and workmanlike manner so as not to affect any insurance coverages
applicable thereto.  Before making any such repairs, Tenant shall notify
Landlord of the damage necessitating the repair in question and afford Landlord
a reasonable opportunity to perform such work (taking into account the exigency
of the situation).  If Tenant makes any repairs under this Section 33 that
Landlord would otherwise have been required to pay for under Section 4.(a), then
Landlord shall reimburse

<PAGE>
 
to Tenant the costs of such repairs within 30 days after Tenant delivers to
Landlord written evidence substantiating all such costs.

     Executed by Tenant on December 18, 1997.

TENANT:                  MILLIPORE CORPORATION, a Massachusetts corporation

                              By:   /s/ J. Edward Lary
                                   ---------------------------------------------
                                    J. Edward Lary, Vice President
                                    Address:  80 Ashby Road
                                    Bedford, Massachusetts 07130
                                    Telephone:      (781) 533-5516
                                    Fax:            (781) 533-3120
 
Executed by Landlord on December 19th, 1997.
 
LANDLORD:                EBP 3, LTD., a Texas limited partnership
                         By:  MIT Unsecured, Inc., a California corporation, its
                              general partner

                              By:   /s/ Timothy B. Keith
                                   ---------------------------------------------
                                    Timothy B. Keith, Vice President
                              Address:    c/o Bob Dobbin
                                          455 Market St #1700
                                          San Francisco, CA 94105
                                          Telephone:   415-228-3900
                                          Fax:         415-284-2840

                              w/or copy to:
                                          1445 Ross Avenue
                                          49th Floor
                                          Dallas, TX 75202
                                          Telephone: 214-978-8512
                                          Fax:       214-855-6792

<PAGE>
 
                                  EXHIBIT A-1

                           [Description of the Land]

<PAGE>
 
                                  EXHIBIT A-2

                          [Depiction of the Building]


<PAGE>
 
                                   EXHIBIT B
                                   ---------


     1.  CONSTRUCTION OF IMPROVEMENTS. Landlord shall diligently construct the
         ----------------------------                                       
Building Shell in accordance with the plans and specifications prepared by the
architect of record, Merriman & Associates, dated August 22, 1997, and last
revised November 6, 1997, and minor change orders thereto (the "SHELL PLANS"),
                                                                -----------   
in a good and workmanlike manner using materials specified in the Shell Plans
and in compliance with Law (defined below).  The Building Shell is referred to
as the "IMPROVEMENTS" Landlord assumes no liability for special, consequential,
        ------------                                                           
or incidental damages of any kind whatsoever in connection with the design or
construction of the Improvements, AND MAKES NO REPRESENTATIONS, WARRANTIES, OR
GUARANTIES REGARDING THE SAME, EXPRESSED OR IMPLIED, INCLUDING, WITHOUT
LIMITATION, WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR
OF HABITABILITY, EXCEPT AS EXPRESSLY SET FORTH HEREIN.  Landlord represents and
warrants to Tenant that upon completion of the Building Shell the exterior
portions of the Premises shall comply with Title III of the American
Disabilities Act of 1990, the Texas Elimination of Architectural Barriers Act,
and all rules and regulations and guidelines promulgated under either of such
acts, as amended from time to time (the "DISABILITIES ACTS"), shall comply with
                                         -----------------                     
all other Laws, and shall not contain any asbestos-containing materials.  If the
foregoing representation and warranty is incorrect, then Landlord shall pay to
Tenant all additional costs incurred by Tenant in constructing alterations,
additions and improvements which Tenant incurred because the Building Shell was
not constructed in compliance with Law or contained asbestos containing
materials.

     2.  SUBSTANTIAL COMPLETION.  "SUBSTANTIAL COMPLETION" shall occur when the
         ----------------------    ----------------------                      
Improvements are substantially completed as certified by the architect preparing
the Shell Plans utilizing AIA document G704, Certificate of Substantial
Completion.  Substantial Completion shall have occurred even though minor
details of construction, decoration, landscaping, and mechanical adjustments
remain to be completed by Landlord.  When the Certificate of Substantial
Completion is issued, Landlord and the architect shall prepare a punch list of
incomplete, minor, detail items and Landlord shall rise all reasonable efforts
to complete such items within 30 days after the Certificate of Substantial
Completion is issued, except as to such items that, by their nature, will take a
longer period to complete as set forth in the punch list.  The "TARGET DATE" for
                                                                -----------     
Substantial Completion of the Improvements is February 1, 1998.  If the actual
date of Substantial Completion is delayed beyond the Target Date because of
events beyond Landlord's reasonable control, including matters of the type
described in Section 23.(c), then Landlord shall have no liability therefor and
the date for Substantial Completion shall be extended by the period of any such
delay.  If Substantial Completion is delayed because of any acts of a Tenant
Party, then the Commencement Date shall not be extended, but rather shall start
on the date on which it would have occurred but for such event.  Except if
Tenant terminates this Lease under Section 1.(b), this Lease shall remain in
full effect notwithstanding any delay in Substantial Completion.

<PAGE>
 
     3.  EARLY ENTRY BY TENANT.  Tenant may enter the Shell Building before
         ---------------------                                            
Substantial Completion with Landlord's prior consent (which shall not be
unreasonably withheld) to perform work therein, provided that (a) Landlord is
given prior written notice of any such entry, (b) such entry shall be
coordinated with Landlord and shall not interfere with Landlord's work, (c)
Tenant shall deliver to Landlord evidence that the insurance required under
Section 9 of this Lease has been obtained, and (d) Tenant shall pay all utility
charges reasonably allocable to Tenant by Landlord in connection with such early
entry.  Tenant shall conduct its activities therein so as not to interfere with
Landlord's construction activities, and shall do so at its risk and expense.
If, in Landlord's judgement, Tenant's activities therein interfere with
Landlord's construction activities, Landlord may terminate Tenant's right to
enter the Premises before Substantial Completion.  After Substantial Completion,
Tenant may enter into the Premises to construct and install the initial tenant
improvements therein.  Any such entry shall be on the terms of this Lease, but
no rent shall accrue in respect of Base Rent or, except as provided above with
respect to utilities, Operating Expenses during the period that Tenant so enters
the Premises before the Commencement Date.

<PAGE>
 
                                   EXHIBIT C
                                   --------- 


                               EXTENSION OPTIONS

     1.   OPTION.  Provided no Event of Default exists when Tenant delivers such
          ------                                                               
notice, Tenant may renew this Lease as to all of the Premises for two additional
period of five years each on the same terms provided in this Lease (except as
set forth below).  On or before the commencement date of the extended Term in
question, Landlord and Tenant shall execute an amendment to this Lease extending
the Term on the same terms provided in this Lease, except as follows:

          (a)  The Base Rent payable for each month during the extended Term in
question shall be the Fair Market Rental Rate determined in accordance with
paragraph 2 below;

          (b)  Tenant shall have no further renewal options unless expressly
granted by Landlord in writing (other than those that have not been exercised
hereunder); and

          (c)  Landlord shall lease to Tenant the Premises in their then-current
condition, and Landlord shall not provide to Tenant any allowances (e.g., moving
allowance, construction allowance, and the like) or other tenant inducements,

     Tenant's rights under this Exhibit shall terminate if (1) this Lease
expires or is cancelled or this Lease or Tenant's right to possession of the
Premises is terminated or (2) Tenant fails timely to exercise its option under
this Exhibit, time being of the essence with respect to Tenant's exercise
thereof.  Tenant's rights under this Exhibit are personal to Tenant and may only
be exercised by Tenant or a Permitted Transferee occupying the entire Premises
at the time the option provided herein is exercised.

     2.   EXERCISE OF OPTION. Tenant shall elect whether to extend the Term by
          ------------------                                                
delivering to Landlord written notice thereof (the "ELECTION NOTICE") not sooner
                                                    ---------------             
than 15 nor later than 9 months before the expiration of the Term.  If Tenant
fails to deliver the Election Notice at least 9 months before the end of the
Term, Tenant's rights under this Exhibit shall terminate; time being of the
essence with respect to such delivery.  Within 30 days after Landlord receives
the Election Notice, Landlord shall deliver to Tenant its assessment of the Fair
Market Rental Rate ("LANDLORD'S ASSESSMENT").  If Tenant disagrees with
                     ---------------------                             
Landlord's Assessment, it shall deliver to Landlord written notice thereof (an
"OBJECTION NOTICE") within 30 days after Landlord delivers to Tenant Landlord's
 ----------------                                                              
Assessment; otherwise, Landlord's Assessment shall be the Base Rent for the
extended Term.  If Tenant timely delivers an Objection Notice, Landlord and
Tenant shall meet to attempt to determine the prevailing rental rate for the
extended Term.  If Tenant and Landlord are unable to agree on such prevailing
rental rate within 15 days after Tenant delivers to Landlord the Objection
Notice, Landlord and Tenant shall jointly appoint an

<PAGE>
 
independent real estate appraiser with at least five-years' commercial real
estate experience in the vicinity of the Premises and submit to the appraiser
its assessment of the prevailing rental rate for the extended Term, together
with the data used to support such assessment. If Landlord and Tenant are unable
to agree on an appraiser within five days after such 15-day period, then either
party may request that the Dallas office of the American Arbitration Association
appoint such appraiser, which appointment shall be binding on Landlord and
Tenant. Within 20 days after its selection, the appraiser shall select the
assessment closest to his determination of the Fair Market Rental Rate for the
extended Term, which assessment shall be the Base Rent for the extended Term.
Landlord and Tenant shall share equally the cost of the appraiser. The term
"FAIR MARKET RENTAL RATE" shall mean the market rental rate for the time period
 -----------------------
such determination is being made for space in comparable office/warehouse/
research/manufacturing buildings in the vicinity of the Building of comparable
condition for space of equivalent quality, size, utility, and location. Such
determination shall take into account all relevant factors, including length of
term, credit standing of Tenant, market concessions and other factors (but shall
not include the value of then-existing improvements that Tenant is entitled to
remove at the end of the Term).

<PAGE>
 
                                  EXHIBIT A-1

                               Legal Description


BEING a 13.894 acre tract out of the Rufus Sewell Survey, Abstract No. 875,
Collin County, Texas; said tract being part of Lot 1, Block 1, Enterprises
Addition No. 2, an addition to the City of Allen, Texas according to the plat
recorded in Cabinet G, Page 457 of the Plat Records of Collin County, Texas;
said 13.894 acre tract being more particularly described as follows:

COMMENCING, at a  1/2-inch iron rod found at the intersection of the south
right-of-way line of Bethany Drive (a 110-foot wide right-of-way) and the east
right-of-way line of Enterprise Boulevard (a 60-foot wide right-of-way); said
point being the northwest corner of said Lot 1, Block 1;

     THENCE, South 20 degrees, 33 minutes, 10 seconds East, along the said east
     line of Enterprise Boulevard and the west line of said Lot 1, a distance of
     153.71 feet to a  1/2-Inch iron rod found at the beginning of a curve to
     the right whose center bears South 69 degrees, 26 minutes, 50 seconds West,
     a distance of 180.00 feet from said point;

     THENCE, in a southerly direction continuing along the said east line of
     Enterprise Boulevard and said curve to the right, through a central angle
     of 34 degrees, 36 minutes, 10 seconds, an arc distance of 108.71 feet to a
     1/2-inch iron rod found at the end of said curve;

     THENCE, South 14 degrees, 03 minutes, 00 seconds West, continuing along the
     said east line of said Enterprise Boulevard, a distance of 511.09 feet to a
     1/2-inch iron rod found at an angle point;

     THENCE, South 11 degrees, 30 minutes, 00 seconds West, continuing along the
     said east line of Enterprise Boulevard, a distance of 315.97 feet to a
     1/2-inch iron rod with "Pacheco Koch" cap set at the POINT OF BEGINNING;

THENCE, South 68 degrees, 03 minutes, 17 seconds East, departing the said east
line of Enterprise Boulevard and the west line of said Lot 1, a distance of
684.35 feet to a 1/2-inch iron rod with "Pacheco Koch" cap set for corner in
the west right-of-way line of Southern Pacific Railroad (a 100-foot wide
railroad right-of-way) and the east line of said Lot 1;

THENCE, South 22 degrees, 08 minutes, 57 seconds West, along the said west line
of Southern Pacific Railroad and the east line of said Lot 1, a distance of
180.01 feet to a  1/2-inch iron rod found at the beginning of a curve to the
right whose center bears North 68 degrees, 05 minutes, 56 seconds West, a
distance of 2814.79 feet from said point;

<PAGE>
 
 THENCE, in a southwesterly direction along the said west line of Southern
 Pacific Railroad and said curve to the right, through a central angle of 19
 degrees, 11 minutes, 30 seconds, an arc distance of 942.84 feet to a 1/2-inch
 iron rod with "Pacheco Koch" cap set for corner;

 THENCE, North 78 degrees, 30 minutes, 00 seconds West, departing the said west
 line of Southern Pacific Railroad and the east line of said Lot 1, a distance
 of 318.84 feet to a  1/2-inch iron rod with "Pacheco Koch" cap set for corner
 in the said east line of Enterprise Boulevard and the west line of said Lot 1;
 said point being on a curve to the left whose center bears North 77 degrees, 49
 minutes, 24 seconds West, a distance of 320.00 feet from said point;

 THENCE, in a northeasterly direction along the said east line of Enterprise
 Boulevard and said curve to the left, through a central angle of 00 degrees, 40
 minutes, 36 seconds, an arc distance of 3.78 feet to a  1/2-inch iron rod found
 at the end of said curve;

 THENCE, North 11 degrees, 30 minutes, 00 seconds East, continuing along the
 said east line of Enterprise Boulevard, a distance of 1179.06 feet to the POINT
 OF BEGINNING;

 CONTAINING, 605,203 square feet of 13.894 acres of land, more or less.

<PAGE>
 
                                  EXHIBIT A-2



                                   [Diagram]