<PAGE>
                                                                     Exhibit 4.1


                          REGISTRATION RIGHTS AGREEMENT

         THIS REGISTRATION RIGHTS AGREEMENT (the "Agreement") is made and
entered into this 5th day of December, 2003 by and among (i) Tegal Corporation,
a Delaware corporation ("Tegal"), (ii) Simplus Systems Corporation, a Delaware
corporation ("Simplus"), and (iii) Kiet Nguyen, in his capacity as the
representative (the "Stockholders' Representative") of all of the stockholders
of Simplus.

                                 R E C I T A L S

         A. On November 10, 2003, Tegal and Simplus entered into an Asset
Acquisition Agreement (the "Asset Acquisition Agreement") pursuant to which
Tegal has agreed to purchase substantially all of the assets, and certain
liabilities, of Simplus in exchange for one million five hundred thousand
(1,500,000) shares (the "Tegal Shares") of Common Stock (as defined in Section 1
below).

         B. In accordance with Section 8 of the Asset Acquisition Agreement,
Tegal has agreed to grant certain registration rights to holders of the Tegal
Shares and other Registrable Securities (as defined in Section 1 below).

         C. Tegal and Simplus enter into this Agreement to memorialize such
registration rights.

         D. Stockholders' Representative joins this Agreement as a party in
accordance with Section 14 of the Stockholder Representation Agreement by and
between Tegal and each of the stockholders of Simplus (all of whom are listed on
Exhibit A to this Agreement) as Simplus intends to liquidate and distribute the
Tegal Shares to its stockholders and creditors soon after the closing of the
transactions contemplated in the Asset Acquisition Agreement.

                                   AGREEMENTS

         NOW, THEREFORE, in consideration of the premises, and of the mutual
covenants and agreements contained herein and other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto hereby agree as follows:

         1. Definitions. In addition to capitalized terms defined elsewhere in
this Agreement, the following capitalized terms shall have the following meaning
when used in this Agreement. Defined terms used, but not defined, herein shall
have the meanings ascribed to them as set forth in the Asset Acquisition
Agreement.

            1.1 "Common Stock" means the common stock, par value $0.01 per
share, of Tegal.
<PAGE>
            1.2 "Exchange Act" means the Securities Exchange Act of 1934, as
amended.

            1.3 "Person" means any person or entity, whether an individual,
whether in their capacity as a trustee, executor, administrator or other legal
representative, sole proprietorship, corporation, limited liability company,
general partnership, limited partnership, trust, unincorporated organization,
syndicate, business association, firm, joint venture, governmental agency or
authority or any similar entity.

            1.4 "Public Offering" means any offering by Tegal of its equity
securities to the public pursuant to an effective registration statement under
the Securities Act or any comparable statement under any comparable federal
statute then in effect.

            1.5 "Registrable Shares" means at any time (i) the Tegal Shares;
(ii) any shares of Common Stock then outstanding which were issued directly or
indirectly as a dividend or other distribution with respect to or in replacement
of the Tegal Shares; and (iii) any shares of Common Stock then issuable directly
or indirectly upon the conversion or exercise of other securities which were
issued as a dividend or other distribution with respect to or in replacement of
the Tegal Shares or the shares referred to in (ii); provided, however, that
Registrable Shares shall not include any shares which have been registered
pursuant to the Securities Act or which have been sold pursuant to Rule 144 of
the Securities Act. For purposes of this Agreement, a Person will be deemed to
be a holder of Registrable Shares whenever such Person has the right to acquire
such Registrable Shares, whether or not such acquisition actually has been
effected.

            1.6 "SEC" means the Securities and Exchange Commission.

            1.7 "Securities Act" means the Securities Act of 1933, as amended.

         2. Registration Rights.

            2.1 Registration. Within ninety (90) days of the Closing, the
holders of Registrable Shares will be entitled to request a single registration
under the Securities Act of their Registrable Shares, if available, on Form S-3
or any similar short-form registration (the "Demand Registration"). Within ten
(10) days after receipt by Tegal of any request pursuant to this Section 2.1,
Tegal will give written notice of such request to all other holders of
Registrable Shares and will include in such registration all such shares with
respect to which Tegal has received written requests for inclusion within ten
(10) days after delivery of Tegal's notice. If the Demand Registration is to be
an underwritten Public Offering, and if the underwriters for marketing or other
reasons request the inclusion in the registration statement of information which
is not required under the Securities Act to be included in a registration
statement on the applicable form for the Demand Registration, Tegal will provide
such information as may be reasonably requested for inclusion by the
underwriters in the Demand Registration.

            2.2 Payment of Expenses for the Demand Registration. Tegal will pay
all Registration Expenses (as defined in Section 5 below) for the Demand
Registration.

            2.3 Restrictions. Tegal may postpone for up to ninety (90) days the
filing or the effectiveness of a registration statement for the Demand
Registration if the Board of Directors of Tegal reasonably and in good faith
determines that such filing would be materially

                                      -2-
<PAGE>
detrimental to Tegal or require a disclosure of a material fact that might
reasonably be expected to have a material adverse effect on Tegal or any plan or
proposal by Tegal or any of its subsidiaries to engage in any acquisition of
assets (other than in the ordinary course of business) or any merger,
consolidation, tender offer or other significant transaction.

            2.4 Selection of Underwriters. The holders of a majority of the
Registrable Shares included in any Demand Registration shall have the right to
select the investment banker(s) and manager(s) to administer the offering,
subject to Tegal's approval.

         3. Holdback Agreements. Each holder of Registrable Shares agrees not to
effect any public sale or distribution of equity securities of Tegal, or any
securities convertible into or exchangeable or exercisable for such securities,
during the seven (7) days prior to, and during the ninety (90) days following,
the effective date of the underwritten Demand Registration in which Registrable
Shares are included (except as part of such underwritten registration), unless
the underwriters managing the Public Offering otherwise agree. Nothing herein
shall prevent a holder of Registrable Shares that is a partnership from making a
distribution of Registrable Shares to its partners, a holder of Registrable
Shares that is a trust from making a distribution of Registrable Shares to its
beneficiaries or a holder of Registrable Shares that is a corporation from
making a distribution of Registrable Shares to its stockholders, provided that
the transferees of such Registrable Shares agree to be bound by the provisions
of this Agreement to the extent the transferor would be so bound.

         4. Registration Procedures. Whenever the holders of Registrable Shares
have requested that any Registrable Shares be registered pursuant to this
Agreement, Tegal will use its reasonable best efforts to effect the registration
and sale of such Registrable Shares in accordance with the intended method of
disposition thereof and, pursuant thereto, Tegal will as expeditiously as
possible:

                (a) prepare and file with the SEC a registration statement with
respect to such Registrable Shares and use its reasonable best efforts to cause
such registration statement to become effective (provided that before filing a
registration statement or prospectus, or any amendments or supplements thereto,
Tegal will furnish copies of all such documents proposed to be filed to the
counsel or counsels for the sellers of the Registrable Shares covered by such
registration statement);

                (b) prepare and file with the SEC such amendments and
supplements to such registration statement and the prospectus(es) used in
connection therewith as may be necessary to keep such registration statement
effective for a period of not less than one (1) year or such shorter period
until such Registrable Shares are no longer Registrable Shares and comply with
the provisions of the Securities Act with respect to the disposition of all
securities covered by such registration statement during such period in
accordance with the intended methods of disposition by the sellers thereof set
forth in such registration statement;

                (c) furnish to each seller of Registrable Shares such number of
copies of such registration statement, each amendment and supplement thereto,
the prospectus(es) included in such registration statement (including each
preliminary prospectus) and such other

                                      -3-
<PAGE>
documents as such seller may reasonably request in order to facilitate the
disposition of the Registrable Shares owned by such seller;

                (d) use its reasonable best efforts to register or qualify such
Registrable Shares under such other securities or blue sky laws of such
jurisdictions as any seller reasonably requests and do any and all other acts
and things which may be reasonably necessary or advisable to enable such seller
to consummate the disposition in such jurisdictions of the Registrable Shares
owned by such seller (provided that Tegal will not be required to (i) qualify
generally to do business in any jurisdiction where it would not otherwise be
required to qualify but for this subparagraph or (ii) consent to general service
of process in any such jurisdiction);

                (e) notify each seller of such Registrable Shares, at any time
when a prospectus relating thereto is required to be delivered under the
Securities Act, of the happening of any event as a result of which the
prospectus included in such registration statement contains an untrue statement
of a material fact or omits any fact necessary to make the statements therein
not misleading, and, at the request of any such seller, Tegal will prepare a
supplement or amendment to such prospectus so that, as thereafter delivered to
the purchasers of such Registrable Shares, such prospectus will not contain any
untrue statement of a material fact or omit to state any fact necessary to make
the statements therein not misleading;

                (f) cause all such Registrable Shares to be listed on each
securities exchange on which similar securities issued by Tegal are then listed
or if no such securities are then listed, such securities exchange as the
holders of a majority of the Registrable Shares included in such registration
may reasonably request;

                (g) enter into such customary agreements (including underwriting
agreements in customary form) and take all such other customary actions as the
holders of a majority of the Registrable Shares being sold or the underwriters,
if any, reasonably request in order to expedite or facilitate the disposition of
such Registrable Shares;

                (h) make available for inspection by any seller of Registrable
Shares, any underwriter participating in any disposition pursuant to such
registration statement, and any attorney, accountant or other agent retained by
any such seller or underwriter, all financial and other records, pertinent
corporate documents and properties of Tegal, and cause Tegal's officers,
directors, employees and independent accountants to supply all information
reasonably requested by any such seller, underwriter, attorney, accountant or
agent in connection with such registration statement; and

                (i) advise each seller of such Registrable Shares, promptly
after it shall receive notice or obtain knowledge thereof, of the issuance of
any stop order by the SEC suspending the effectiveness of such registration
statement or the initiation or threatening of any proceeding for such purpose
and promptly use all reasonable efforts to prevent the issuance of any stop
order or to obtain its withdrawal if such stop order should be issued.

         5. Registration Expenses. All expenses incident to Tegal's performance
of or compliance with this Agreement, including, but not limited to, all
registration and filing fees, fees and expenses of compliance with securities or
blue sky laws, printing expenses, messenger

                                      -4-
<PAGE>
and delivery expenses, and fees and disbursements of counsel for Tegal and all
independent certified public accountants, underwriters (excluding discounts and
commissions which shall be payable by the holders of Registrable Shares) and
other Persons retained by Tegal (all such expenses being herein called
"Registration Expenses"), will be borne by Tegal, provided that Tegal shall not
be required to pay sales commissions, discounts or transfer taxes. In addition,
Tegal will pay its internal expenses (including, but not limited to, all
salaries and expenses of its officers and employees performing legal or
accounting duties), the expense of any annual audit or quarterly review, the
expense of any liability insurance obtained by Tegal and the expenses and fees
for listing the securities to be registered on each securities exchange.

         6. Indemnification.

            6.1 By Tegal. Tegal agrees to indemnify, to the extent permitted by
law, each holder of Registrable Shares, its officers, employees and directors
and each Person who controls such holder (within the meaning of the Securities
Act) against all losses, claims, damages, liabilities and expenses (including,
but not limited to, attorneys' fees and expenses) caused by any untrue or
alleged untrue statement of material fact contained in any registration
statement, prospectus or preliminary prospectus, or any amendment thereof or
supplement thereto, or any omission or alleged omission of a material fact
required to be stated therein or necessary to make the statements therein not
misleading, except insofar as the same are caused by or contained in any
information furnished in writing to Tegal by such holder expressly for use
therein or by such holder's failure to deliver a copy of the prospectus or any
amendments or supplements thereto after Tegal has furnished such holder with a
sufficient number of copies of the same. In connection with an underwritten
offering, Tegal will indemnify such underwriters, their officers and directors
and each Person who controls such underwriters (within the meaning of the
Securities Act) to the same extent as provided above with respect to the
indemnification of the holders of Registrable Shares. The payments required by
this Section 6.1 will be made periodically during the course of the
investigation or defense, as and when bills are received or expenses incurred.

            6.2 By Each Holder. In connection with any registration statement in
which a holder of Registrable Shares is participating, each such holder will
furnish to Tegal in writing such information as Tegal reasonably requests for
use in connection with any such registration statement or prospectus and, to the
extent permitted by law, will indemnify Tegal, its directors, employees and
officers and each Person who controls Tegal (within the meaning of the
Securities Act) against any losses, claims, damages, liabilities and expenses
resulting from any untrue or alleged untrue statement of material fact contained
in the registration statement, prospectus or preliminary prospectus, or any
amendment thereof or supplement thereto, or any omission or alleged omission of
a material fact required to be stated therein or necessary to make the
statements therein not misleading, but only to the extent that such untrue
statement or omission is contained in or omitted from any information so
furnished in writing by such holder for the acknowledged purpose of inclusion in
such registration statement, prospectus or preliminary prospectus; provided that
the obligation to indemnify will be several, not joint and several, among such
holders of Registrable Shares and the liability of each such holder of
Registrable Shares will be in proportion to and limited in all events to the net
amount received by such holder from the sale of Registrable Shares pursuant to
such registration statement.

                                      -5-
<PAGE>
            6.3 Procedure. Any Person entitled to indemnification hereunder will
(a) give prompt written notice to the indemnifying Person of any claim with
respect to which it seeks indemnification and (b) unless in such indemnified
Person's reasonable judgment a conflict of interest between such indemnified and
indemnifying parties may exist with respect to such claim, permit such
indemnifying Person to assume the defense of such claim with counsel reasonably
satisfactory to the indemnified Person. If such defense is assumed, the
indemnifying Person will not be subject to any liability for any settlement made
by the indemnified Person without its consent (but such consent will not be
unreasonably withheld). An indemnifying Person who is not entitled to, or elects
not to, assume the defense of a claim will not be obligated to pay the fees and
expenses of more than one counsel for all parties indemnified by such
indemnifying Person with respect to such claim, unless in the reasonable
judgment of any indemnified Person a conflict of interest may exist between such
indemnified Person and any other of such indemnified parties with respect to
such claim.

            6.4 Survival. The indemnification provided for under this Agreement
will remain in full force and effect regardless of any investigation made by or
on behalf of the indemnified Person or any officer, director or controlling
Person of such indemnified Person and will survive the transfer of securities.
Tegal also agrees to make such provisions as are reasonably requested by any
indemnified Person for contribution to such Person in the event Tegal's
indemnification is unavailable for any reason.

         7. Compliance with Rule 144 and Rule 144A. So long as Tegal files
reports under Section 13 or 15(d) of the Exchange Act, then at the request of
any holder of Registrable Shares who proposes to sell securities in compliance
with Rule 144 of the Securities Act, Tegal will (a) forthwith furnish to such
holder a written statement of compliance with the filing requirements of the
Securities Act as set forth in Rule 144, as such rule may be amended from time
to time and (b) make available to the public and such holders such information
as will enable the holders of Registrable Shares to make sales pursuant to Rule
144. At any time that Tegal is not subject to Section 13 or 15(d) of the
Exchange Act, Tegal will provide to the holder of Registrable Shares and to any
prospective purchaser of Registrable Shares under Rule 144A of the Securities
Act, the information described in Rule 144A(d)(4) of the Securities Act.

         8. Participation in Underwritten Registrations. No Person may
participate in any registration hereunder which is underwritten unless such
Person (a) agrees to sell its securities on the basis provided in any
underwriting arrangements approved by such Person or Persons entitled hereunder
to approve such arrangements and (b) completes and executes all questionnaires,
powers of attorney, custody agreements, indemnities, underwriting agreements and
other documents reasonably required under the terms of such underwriting
arrangements.

         9. Miscellaneous.

            9.1 No Inconsistent Agreements. Tegal will not hereafter enter into
any agreement with respect to its securities which is inconsistent with or which
otherwise materially limits, restricts or interferes with the rights granted to
the holders of Registrable Shares in this Agreement.

                                      -6-
<PAGE>
            9.2 Amendments and Waivers. Except as otherwise expressly provided
herein, the provisions of this Agreement may be amended or waived at any time
only by the written agreement of Tegal and the holders of a majority of the
Registrable Shares; provided, however, that the provisions of this Agreement may
not be amended or waived without the consent of the holders of all the
Registrable Shares adversely affected by such amendment or waiver if such
amendment or waiver adversely affects a portion of the Registrable Shares but
does not so adversely affect all of the Registrable Shares. Any waiver, permit,
consent or approval of any kind or character on the part of any such holders of
any provision or condition of this Agreement must be made in writing and shall
be effective only to the extent specifically set forth in writing. Any amendment
or waiver effected in accordance with this paragraph shall be binding upon each
holder of Registrable Shares and Tegal.

            9.3 Successors and Assigns. Except as otherwise expressly provided
herein, all covenants and agreements contained in this Agreement by or on behalf
of any of the parties hereto will bind and inure to the benefit of the
respective successors and assigns of the parties hereto, whether so expressed or
not. In addition, and whether or not any express assignment has been made, the
provisions of this Agreement which are for the benefit of Simplus, the
stockholders of Simplus or holders of Registrable Shares are also for the
benefit of, and enforceable by, any subsequent holders of such Registrable
Shares.

            9.4 Descriptive Headings. The descriptive headings of this Agreement
are inserted for convenience of reference only and do not constitute a part of
and shall not be utilized in interpreting this Agreement.

            9.5 Notices. Any notices required or permitted to be sent hereunder
shall be delivered personally or mailed, certified mail, return receipt
requested, or delivered by overnight courier service to the following addresses,
or such other address as any party hereto designates by written notice to Tegal,
and shall be deemed to have been given upon delivery, if delivered personally,
three (3) days after mailing, if mailed, or one (1) business day after delivery
to the courier, if delivered by overnight courier service:

<TABLE>
<S>                                            <C>
If to Simplus:                                 With a copy to:
   Larry Matheny, Ph.D.                           Keith S. Koegler
   President                                      Ritchey Fisher Whitman & Klein
   Simplus Systems Corporation                    1717 Embarcadero Road
   40737 Encyclopedia Circle                      Palo Alto, CA  94303
   Fremont, CA  94538                             Fax:  (650) 857-1288
   Fax:  (510) 226-4871                           email:  kkoegler@rfwk.com
   email:  larrymath@aol.com
</TABLE>

              If to Stockholders' Representative or to the stockholders of
Simplus:

                  Kiet Nguyen
                  40725 Encyclopedia Circle
                  Fremont, CA  94538
                  Fax:  (510) 770-5002
                  email:  knugen@klncorp.com

                                      -7-
<PAGE>
<TABLE>
<S>                                                           <C>
              If to Tegal:                                    With a copy to:
                  Thomas R. Mika                                  Scott Willoughby
                  Chief Financial Officer                         Latham & Watkins LLP
                  Tegal Corporation                               505 Montgomery Street, Suite 1900
                  2201 South McDowell Blvd.                       San Francisco, CA  94111-2562
                  Petaluma, CA  94954-6903                        Fax:  (415) 395-8095
                  Fax:  (707) 763-0436                            email:  scott.willoughby@lw.com
                  email:  tmika@tegal.com
</TABLE>

If to holders of the Registrable Shares other than Simplus or the stockholders
of Simplus, to the addresses set forth on the stock record books of Tegal.

            9.6 Execution in Counterparts. This Agreement may be executed in any
number of counterparts, each of which when so executed and delivered shall be
deemed an original, and such counterparts together shall constitute one
instrument.

            9.7 Governing Law. This Agreement and the transactions contemplated
hereby shall be construed in accordance with, and governed by, the laws of the
State of California; provided, however, that matters of Delaware corporate law
shall be governed by the Delaware General Corporation Laws.

            9.8 Consent to Jurisdiction. Each of the parties hereto (a) consents
to submit itself to the personal jurisdiction of the federal and state courts
located in Petaluma, California in the event any dispute arises out of this
Agreement or any of the transactions contemplated hereby, (b) agrees that it
will not attempt to deny or defeat such personal jurisdiction by motion or other
request for leave from any such court, and (c) agrees that it will not bring any
action relating to this Agreement in any court other than a federal or state
court located in Petaluma, California.

            9.9 WAIVER OF JURY TRIAL. EACH OF THE PARTIES HERETO HEREBY WAIVES
ITS RESPECTIVE RIGHT TO A JURY TRIAL OF ANY PERMITTED CLAIM OR CAUSE OF ACTION
ARISING OUT OF THIS AGREEMENT, ANY OF THE TRANSACTIONS CONTEMPLATED HEREBY, OR
ANY DEALINGS BETWEEN ANY OF THE PARTIES HERETO RELATING TO THE SUBJECT MATTER OF
THIS AGREEMENT OR ANY OF THE TRANSACTIONS CONTEMPLATED HEREBY. THE SCOPE OF THIS
WAIVER IS INTENDED TO BE ALL ENCOMPASSING OF ANY AND ALL DISPUTES THAT MAY BE
FILED IN ANY COURT AND THAT RELATE THE SUBJECT MATTER OF THIS AGREEMENT OR ANY
OF THE TRANSACTIONS CONTEMPLATED HEREBY, INCLUDING, WITHOUT LIMITATION, CONTRACT
CLAIMS, TORT CLAIMS, AND ALL OTHER COMMON LAW AND STATUTORY CLAIMS. THIS WAIVER
IS IRREVOCABLE, MEANING THAT IT MAY NOT BE MODIFIED EITHER ORALLY OR IN WRITING,
AND THIS WAIVER SHALL APPLY TO ANY SUBSEQUENT AMENDMENTS, SUPPLEMENTS OR OTHER
MODIFICATIONS TO THIS AGREEMENT, ANY OF THE

                                      -8-
<PAGE>
TRANSACTIONS CONTEMPLATED HEREBY OR TO ANY OTHER DOCUMENT OR AGREEMENT RELATING
TO THE TRANSACTIONS CONTEMPLATED HEREBY.

            9.10 Service of Process. Each of the parties hereto irrevocably
consents to the service of any process, pleading, notices or other papers by the
mailing of copies thereof by registered, certified or first class mail, postage
prepaid, to such party at such party's address set forth herein, or by any other
method provided or permitted under California law.

            9.11 Reproduction of Documents. This Agreement and all documents
relating hereto, including, but not limited to, (a) consents, waivers,
amendments and modifications which may hereafter be executed and (b)
certificates and other information previously or hereafter furnished, may be
reproduced by any photographic, photostatic, microfilm, optical disk,
micro-card, miniature photographic or other similar process. The parties agree
that any such reproduction shall be admissible in evidence as the original
itself in any judicial or administrative proceeding, whether or not the original
is in existence and whether or not such reproduction was made by a party in the
regular course of business, and that any enlargement, facsimile or further
reproduction of such reproduction shall likewise be admissible in evidence.

            9.12 Remedies. Each of the parties to this Agreement will be
entitled to enforce its rights under this Agreement specifically, to recover
damages by reason of any breach of any provision of this Agreement and to
exercise all other rights existing in its favor. The parties hereto agree and
acknowledge that money damages may not be an adequate remedy for any breach of
the provisions of this Agreement and that any party shall be entitled to
immediate injunctive relief or specific performance without bond or the
necessity of showing actual monetary damages in order to enforce or prevent any
violations of the provisions of this Agreement.

            9.13 Severability. Whenever possible, each provision of this
Agreement will be interpreted in such manner as to be effective and valid under
applicable law, but if any provision of this Agreement is held to be prohibited
by or invalid under applicable law, such provision will be ineffective only to
the extent of such prohibition or invalidity, without invalidating the remainder
of this Agreement.

            9.14 Final Agreement. This Agreement, together with the Asset
Acquisition Agreement and all other agreements entered into by the parties
hereto pursuant to the Asset Acquisition Agreement, constitutes the complete and
final agreement of the parties concerning the matters referred to herein, and
supersedes all prior agreements and understandings.

            9.15 No Strict Construction. The language used in this Agreement
will be deemed to be the language chosen by the parties hereto to express their
mutual intent, and no rule of strict construction will be used against any
Person.

                                   * * * * * *

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<PAGE>
         The parties hereto have executed this Registration Rights Agreement as
of the date first set forth above.

                                              TEGAL CORPORATION

                                              By:        /s/ Thomas R. Mika
                                                         Thomas R. Mika
                                                         Chief Financial Officer



                                              SIMPLUS SYSTEMS CORPORATION

                                              By:        /s/ Lawrence Matheny
                                                         Lawrence Matheny, Ph.D.
                                                         President



                                              STOCKHOLDERS' REPRESENTATIVE

                                              By:        /s/ Kiet Nguyen
                                                         Kiet Nguyen

                              SIGNATURE PAGE TO THE
                          REGISTRATION RIGHTS AGREEMENT

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