EXHIBIT 10.20
                                                                   -------------


================================================================================

                          BORROWER'S SECURITY AGREEMENT


                                     made by



                               SIMTEK CORPORATION



                                   in favor of


                RENAISSANCE CAPITAL GROWTH & INCOME FUND III, INC


                                       and


                    RENAISSANCE US GROWTH & INCOME TRUST PLC

                                       and

                      BFSUS SPECIAL OPPORTUNITIES TRUST PLC



                            Dated as of June 28, 2002


================================================================================

<PAGE>



     This BORROWER'S SECURITY AGREEMENT (this "Agreement"), dated as of June 28,
2002, is entered into by and among SIMTEK  CORPORATION,  a Colorado  corporation
("Borrower"), RENAISSANCE US GROWTH & INCOME TRUST PLC, a public limited company
registered in England and Wales ("RUSGIT"),  BFSUS SPECIAL  OPPORTUNITIES  TRUST
PLC,  a public  limited  company  registered  in  England  and Wales  ("BFSUS"),
RENAISSANCE  CAPITAL  GROWTH  &  INCOME  FUND  III,  INC.,  a Texas  corporation
("Renaissance  III")  (RUSGIT,  Renaissance  III, and BFSUS,  together  with any
permitted  assignees or  successors in interest,  referred to as "Lender"),  and
RENAISSANCE  CAPITAL GROUP, INC., a Texas  corporation,  as agent for the Lender
(the "Agent").

Unless indicated otherwise,  all capitalized terms used herein, but not defined,
shall have the  meaning  given to them in the  Convertible  Loan  Agreement  (as
defined   below).   All   references   herein  to  Borrower  shall  include  the
Subsidiaries, unless the context otherwise requires.

                                    RECITALS

     A. Lender,  Borrower and Agent entered into that certain  Convertible  Loan
Agreement,  dated June 28, 2002 (the "Convertible Loan Agreement"),  pursuant to
which  Lender  will lend to Borrower  the  aggregate  principal  amount of Three
Million  Dollars  ($3,000,000)  evidenced by the  Borrower's  7.50%  Convertible
Debentures of even date herewith (the "Debentures").

     B. As a condition for the loan pursuant to the Convertible  Loan Agreement,
Lender required that Borrower grant a security  interest in all of its assets as
collateral  for the loan and any other  indebtedness  of Borrower to Lender (the
"Obligations")  as set forth in the Convertible Loan Agreement.  The Obligations
shall  also  consist  of  payment  of the  costs  and  expenses  of that sale or
realization,  including  compensation to Lender and its agents and counsel,  and
all expenses, liabilities, and advances made or incurred by Lender in connection
therewith, all as set forth in the Convertible Loan Agreement.

     NOW,  THEREFORE,  in consideration of the foregoing recitals and the mutual
covenants and agreements set forth herein, the parties agree as follows:

     1. GRANT OF SECURITY  INTEREST.  In order to secure payment when due of the
Obligations  now existing or hereafter  incurred,  Borrower  hereby  irrevocably
grants to the Lender a continuing security interest in the following property of
the Borrower  (the  "Collateral"),  whether now owned or existing,  or hereafter
acquired,  owned, existing or arising (whether by contract or operation of law),
and wherever located,  which shall be retained by Lender,  until the Obligations
have been paid in full or the  Convertible  Loan Agreement has been  terminated;
provided,  however,  that  such  lien in the  Collateral  shall be  subject  and
subordinate to the liens granted by Borrower to the Senior  Creditor (as defined
in the Subordination and Intercreditor  Agreement), in accordance with the terms
set forth in the Subordination and Intercreditor Agreement:

         (a)  All  accounts  (including  inter-company  receivables),   contract
rights,  chattel  paper  and  rights of  payment  of every  kind  (collectively,
"Accounts") and instruments and general intangibles of Borrower.

         (b) All bank accounts of Borrower.

         (c) All monies and property of any kind of  Borrower,  now or hereafter
in the possession or under the control of Lender, Agent or a bailee of Lender.



<PAGE>


         (d) All licenses, patents (as more particularly described on Schedule 1
attached hereto and incorporated herein for all purposes),  patent applications,
copyrights,  trademarks,  trademark  applications,  trade names,  assumed names,
service marks and service mark applications and other  intellectual  property of
Borrower.

         (e) All inventory,  equipment  (including any and all computer hardware
and  components),  machinery  and fixtures of Borrower in all forms and wherever
located,  and all parts and products thereof,  all accessories  thereto, and all
documents therefor.

         (f) All books and  records  (including,  without  limitation,  customer
lists,  credit  files,  tapes,  ledger  cards,  computer  software and hardware,
electronic  data processing  software,  computer  programs,  printouts and other
computer materials and records) of Borrower evidencing or containing information
regarding or otherwise pertaining to any of the foregoing.

         (g)  Contract  rights  under   agreements   between  Borrower  and  its
Subsidiaries.

         (h)  All  accessories  to,  substitutions  for  and  all  replacements,
products and proceeds of the foregoing,  including, without limitation, proceeds
of insurance  policies insuring the Collateral  (including,  but not limited to,
claims paid and premium refunds).

     2. INSURANCE ON COLLATERAL. Borrower further warrants and agrees that it in
each case  where the terms of any such  Accounts  require  the  Borrower  or the
account  debtor named in such Account to place or carry  insurance in respect of
the property to which such Account  relates,  the Borrower or the account debtor
will pay for and maintain such insurance.

     3.  COVENANT FOR ACCOUNTS.

         (a) The Borrower  will, on the Lender's  demand,  make notations on its
books and records showing the Lender's  security interest and, upon such demand,
make  available  to the Lender  shipping and delivery  receipts  evidencing  the
shipment of the goods that gave rise to an account,  completion  certificates or
other proof of the  satisfactory  performance  of services  that gave rise to an
account,  a copy of the  invoice  for each  account  and  copies of any  written
contract  or order from which an account  arose.  The  Borrower  shall  promptly
notify the Lender if Borrower becomes aware that an account in excess of $15,000
becomes  evidenced  or secured by an  instrument  or chattel  paper and upon the
Lender's request,  will promptly deliver any such instrument or chattel paper to
the Lender,  including any letter of credit delivered to the Borrower to support
a shipment of inventory by the Borrower.

         (b) The Borrower  will promptly  advise the Lender  whenever an account
debtor  refuses to retain or returns any goods valued at more than $100,000 from
the sale of which an account  arose and will comply with any  instructions  that
the Lender may give  regarding  the sale or other  disposition  of such  returns
provided,  however, that the aforementioned  covenants set forth in this Section
3(b) shall not apply to the returning of goods in Borrower's  ordinary course of
business or as may be  specified  in  agreements  between  Borrower and any such
account debtor. From time to time with such frequency as the Lender may request,
the Borrower will report to the Lender all credits  given to account  debtors on
all accounts.

         (c) Except with respect to contracts entered into by Q-DOT, Inc. in the
ordinary course of business  consistent  with past practices,  the Borrower will
immediately  notify the Lender if any account  arises out of contracts  with the
United States or any department,  agency or  instrumentality  thereof,  and with
respect to all such contracts to which Borrower or Q-DOT,  Inc. is a party, will


                                       2
<PAGE>


execute any  instruments  and take any steps  required by the Lender so that all
monies due and to become due under such contract shall be assigned to the Lender
and  notice  of the  assignment  given to and  acknowledged  by the  appropriate
government agency or authority under the Federal Assignment of Claims Act.

         (d) Subject to the rights of the Senior Creditor, at any time after the
occurrence  of an Event of Default as addressed in Section 6 below,  and without
notice to the  Borrower,  the Lender may direct any persons who are  indebted to
the Borrower on any Collateral  consisting of accounts or general intangibles to
make payment directly to the Lender of the amounts due.  Following such Event of
Default, the Lender is authorized to collect,  compromise,  endorse and sell any
such  Collateral in its own name or in the Borrower's  name and to give receipts
to such account  debtors for any such  payments and the account  debtors will be
protected in making such payments to the Lender.

         (e) Subject to the rights of the Senior Creditor, at any time after the
occurrence  of an Event of  Default  (as  addressed  in  Section 6 below),  upon
Agent's  request,  upon the occurrence and during the continuance of an Event of
Default (as addressed in Section 6 hereof),  Borrower  will,  at any  reasonable
time and at Borrower's own expense,  physically  deliver to Agent,  all Accounts
(including inter-company  receivables) assigned to Agent at any reasonable place
or places  designated  by Agent.  Failure to deliver any Account,  or failure to
deliver physical possession of any instruments, documents or writings in respect
of any Account shall not invalidate  Agent's Lien and security interest therein,
except to the extent that  possession  may be required by applicable law for the
perfection of said Lien or security interest,  in which latter case, the Account
shall be deemed to be held by the Borrower as the custodian agent of Agent,  for
the benefit of Lender. Failure of Agent to demand or require Borrower to include
any Account in any schedule,  to execute any schedule, to assign and deliver any
schedule or to deliver  physical  possession  of any  instruments,  documents or
writings related to any Account shall not relieve Borrower of its duty so to do.

         (f) Borrower  hereby agrees that it shall use  commercially  reasonable
efforts,  at its sole cost and  expense  and in its own name,  to  promptly  and
diligently  collect and enforce  payment of all Accounts in accordance with this
Agreement and Borrower  will defend and hold Lender and Agent  harmless from any
and all loss, damage,  penalty,  fine or expense arising from such collection or
enforcement.

     4.  FINANCING   STATEMENTS.   Borrower  agrees  to  execute  all  financing
statements  and  amendments  thereto  as Agent,  on behalf  of the  Lender,  may
reasonably  request from time to time to evidence the security  interest granted
to Agent  hereunder and will pay the cost of all filing fees and taxes,  if any,
necessary to effect the filing thereof.  By its signature  hereon,  the Borrower
hereby irrevocably  authorizes the Lender to execute (on behalf of the Borrower)
and file against the Borrower one or more  financing,  continuation or amendment
statements   pursuant  to  the  Uniform   Commercial  Code  in  form  reasonably
satisfactory to the Lender,  and the Borrower will pay the cost of preparing and
filing the same in all  jurisdictions in which such filing is reasonably  deemed
by the Lender to be necessary  or  desirable  in order to perfect,  preserve and
protect  its  security  interests  in  accordance  with this  Agreement  and the
Convertible  Loan  Agreement,  provided that Lender shall provide  Borrower with
copies of any such  filings,  promptly  after making such  filings.  Without the
written  consent of Agent,  Borrower will not allow any  financing  statement or
notice of assignment to be on file in any public office covering any Collateral,
proceeds  thereof or other matters subject to the security  interest  granted to
Agent herein, unless such financing statement relates to a Permitted Lien.

     5.  LENDER'S  PAYMENT  OF  CLAIMS.  Lender  may,  in its  sole  discretion,
discharge or obtain the release of any Lien  asserted by any Person  against the


                                       3
<PAGE>


Collateral,  other than a Permitted Lien which,  in the Lender's  judgment,  may
have a  Material  Adverse  Effect on the  Lender's  rights  with  respect to the
Collateral.  All sums paid by Lender in respect  thereof  shall be  payable,  on
demand, by Borrower to Lender and shall be a part of the Obligations.

     6. REPRESENTATIONS AND COVENANTS OF BORROWER. Borrower hereby represents to
and agrees with Lender as follows:

         (a) Borrower owns the  Collateral as sole owner,  free and clear of any
Liens, other than Permitted Liens.

         (b) So long as any  Obligations  remain unpaid,  Borrower agrees not to
sell,  assign or transfer the Collateral,  other than sales of Collateral in the
ordinary  course of  business,  and to  maintain it free and clear of any Liens,
other than Permitted Liens.

     7.  DEFAULT AND REMEDIES.

         (a) Borrower  shall be in default  hereunder  upon the occurrence of an
Event of Default, as set forth in the Convertible Loan Agreement.

         (b) Upon the occurrence and during the  continuation of any Default (i)
unless  Lender or Agent shall elect  otherwise,  the entire unpaid amount of the
Obligations due under the Convertible Loan Agreement,  as are not then otherwise
due and payable,  shall become  immediately  due and payable  without  notice to
Borrower  or demand by Lender or Agent and (ii)  either  Lender or Agent may, at
its or their option,  exercise from time to time any and all rights and remedies
available to them under the Uniform Commercial Code or otherwise,  including the
right to foreclose or otherwise  realize upon the  Collateral  and to dispose of
any  of the  Collateral  at one  or  more  public  or  private  sales  or  other
proceedings,  and Borrower agrees that any of Lender, Agent or their nominee may
become the purchaser at any such sale or sales. Borrower agrees that twenty (20)
days shall be  reasonable  prior  notice of the date of any public sale or other
disposition  of the same. All rights and remedies  granted  Lender  hereunder or
under any other agreement between Lender and Borrower shall be deemed concurrent
and  cumulative and not  alternative,  and Lender,  or Agent on its behalf,  may
proceed with any number of remedies at the same time or at different times until
all the Obligations are fully satisfied. The exercise of any one right or remedy
shall not be deemed a waiver or release  of, or an election  against,  any other
right or remedy.  Borrower shall pay to Lender or Agent, on demand,  any and all
expenses  (including  reasonable  attorneys'  fees and legal expenses) which may
have been incurred by Lender or Agent (i) in the  prosecution  or defense of any
action  arising  under this  Agreement,  the  Convertible  Loan  Agreement,  the
Collateral or any of Lender's  rights therein or thereto;  or (ii) in connection
with the custody, preservation, use, operation,  preparation for sale or sale of
the  Collateral,  the  incurring  of all of which are hereby  authorized  to the
extent Lender or Agent deem the same advisable.  Borrower's  liability to Lender
or Agent for any such payment shall be included in the Obligations.

     8. APPLICATIONS OF PROCEEDS OF COLLATERAL.  Upon a foreclosure or otherwise
sale of the Collateral,  the proceeds of any sale of, or other realization upon,
all or any part of the  Collateral,  and any other  monies held by Lender  under
this Agreement, shall be applied in the following order of priority:

         (a)  First,  to  payment  of the  costs  and  expenses  of that sale or
realization,  including  compensation to Lender and its agents and counsel,  and
all expenses, liabilities, and advances made or incurred by Lender in connection
therewith;

         (b) Second, to payment of the interest in full;


                                       4
<PAGE>


         (c) Third, to the payment of the Principal Amount; and

         (d)  Finally,  to  payment  of any  surplus  then  remaining  from such
proceeds  and other  monies to Borrower or its  successors  or assigns,  or as a
court of competent jurisdiction may direct.

     If the  proceeds  of the  Collateral  shall  not  suffice  to pay all items
specified in clauses (a), (b), and (c) above,  Borrower  shall remain liable for
the deficiency.

     10.  ATTORNEY-IN-FACT.  Upon the occurrence and  continuation of a Default,
Lender is hereby  appointed  Borrower's  attorney-in-fact,  for the  purpose  of
carrying  out the  provisions  of this  Agreement  and  taking  any  action  and
executing  any  instruments  which  Lender may deem  necessary  or  advisable to
accomplish  the  purposes  hereof.   This  appointment  as  attorney-in-fact  is
irrevocable  and coupled with an interest.  Without  limiting the  generality of
this appointment, upon such Default (i) Lender shall have the right and power to
receive,  endorse,  and collect all checks made payable to the order of Borrower
which  represent any dividend,  interest,  or other payment or  distribution  in
respect  of all or any of the  Obligations  and to give full  discharge  for the
same, and (ii) Lender shall have the right to exercise, as Borrower's proxy, the
powers of voting and consent pertaining to the Obligations or any part thereof.

     11. MISCELLANEOUS.

         (a) This  Agreement  shall bind and inure to the benefit of the parties
and their respective heirs,  personal  representatives,  successors and assigns,
except that Borrower  shall not assign any of its rights  hereunder  without the
prior written consent of holders of more than 50% of the principal amount of the
then outstanding Debentures.

         (b) Any provision  hereof which is prohibited or  unenforceable  in any
jurisdiction  shall,  as to such  jurisdiction,  be ineffective to the extent of
such  prohibition  or   unenforceability   without  affecting  the  validity  or
enforceability   of  the  remainder  of  this   Agreement  or  the  validity  or
enforceability of such provision in any other jurisdiction.

         (e) This  Agreement  shall be governed by and construed and enforced in
accordance  with the substantive  laws of the State of Texas,  without regard to
the conflicts of laws provisions thereof,  and the applicable laws of the United
States. Venue and jurisdiction shall be in the state or federal courts in Dallas
County, Texas.

         (f) Borrower hereby  consents to the  jurisdiction of the courts of the
State of Texas in any action or proceeding which may be brought against it under
or in connection with this Agreement or any transaction  contemplated  hereby or
to enforce any agreement  contained  herein and, in the event any such action or
proceeding  shall be  brought  against  it,  Borrower  agrees  not to raise  any
objection to such jurisdiction or to the laying of venue in Dallas County, Texas
or, if applicable, any other county in any state in which Collateral is located.

         (g)  All  capitalized  terms,  unless  otherwise  specified,  have  the
meanings assigned to them in the Convertible Loan Agreement and the Debentures.

         (h) Any notices or other  communications  required or  permitted  to be
given by this  Agreement  or any other  documents  and  instruments  referred to
herein must be (i) given in writing and personally delivered,  mailed by prepaid
certified or registered  mail or sent by overnight  service,  such as FedEx,  or
(ii) made by telex or facsimile  transmission  delivered or  transmitted  to the
party to whom such  notice  or  communication  is  directed,  with  confirmation
thereupon  given in  writing  and  personally  delivered  or mailed  by  prepaid
certified or registered mail.

                                       5
<PAGE>



     If to Borrower:          Simtek Corporation
                              4250 Buckingham Dr., Suite 100
                              Colorado Springs, CO 80907
                              Attn:    Douglas M. Mitchell
                              Telephone:        (719) 531-9444
                              Telecopier:       (719) 531-9481

     With a copy to:          Holme Roberts & Owen LLP
                              1700 Lincoln, Suite 4100
                              Denver, CO 80203
                              Attn:    Garth B. Jensen
                              Telephone:        (303) 861-7000
                              Telecopier:       (303) 866-0200

     If to Lender:            Renaissance Capital Growth & Income Fund III, Inc.
                              c/o Renaissance Capital Group, Inc.
                              8080 N. Central Expressway, Suite 210-LB59
                              Dallas, TX 75206
                              Attn:    Russell Cleveland
                                       President and CEO
                              Telephone:      (214) 891-8294
                              Telecopier:     (214) 891-8291

                              Renaissance US Growth & Income Trust PLC
                              c/o Renaissance Capital Group, Inc.
                              8080 N. Central Expressway, Suite 210-LB59
                              Dallas, TX 75206
                              Attn:    Russell Cleveland
                                       President and CEO
                              Telephone:      (214) 891-8294
                              Telecopier:     (214) 891-8291

                              BFSUS Special Opportunities Trust PLC
                              c/o Renaissance Capital Group, Inc.
                              8080 N. Central Expressway, Suite 210-LB59
                              Dallas, TX 75206
                              Attn:    Russell Cleveland
                                       President and CEO
                              Telephone:      (214) 891-8294
                              Telecopier:     (214) 891-8291

     with a copy to:          Kirkpatrick & Lockhart LLP
                              2828 N. Harwood, Suite 1800
                              Dallas, TX 75201
                              Attn:    Norman R. Miller
                              Telephone:      (214) 939-4906
                              Telecopier:     (214) 939-4949


                                       6
<PAGE>



     If to Agent:             Renaissance Capital Group, Inc.
                              8080 N. Central Expressway, Suite 210-LB59
                              Dallas, TX 75206
                              Attn:    Russell Cleveland
                                       President and CEO
                              Telephone:      (214) 891-8294
                              Telecopier:     (214) 891-8291

     with a copy to:          Kirkpatrick & Lockhart LLP
                              2828 N. Harwood, Suite 1800
                              Dallas, TX 75201
                              Attn:    Norman R. Miller
                              Telephone:      (214) 939-4906
                              Telecopier:     (214) 939-4949


         (g) Any notice delivered  personally in the manner provided herein will
be deemed  given to the party to whom it is  directed  upon the  party's (or its
agent's) actual receipt.  Any notice addressed and mailed in the manner provided
herein will be deemed given to the party to whom it is addressed at the close of
business,  local time of the recipient, on the fourth business day after the day
it is placed in the mail, or, if earlier, the time of actual receipt.



                            [Signature page follows]


                                       7
<PAGE>


     IN WITNESS WHEREOF, this Agreement has been duly executed as of the
date and year written above.

                             BORROWER:

                             SIMTEK CORPORATION


                             By: /s/ Douglas Mitchell
                                 -----------------------------------------------
                                 Douglas Mitchell
                                 Chief Executive Officer and President

                             LENDER:

                             BFSUS SPECIAL OPPORTUNITIES TRUST PLC


                             By: /s/ Russell Cleveland
                                 -----------------------------------------------
                                 Russell Cleveland
                                 President and CEO

                             RENAISSANCE US GROWTH & INCOME TRUST PLC


                             By: /s/ Russell Cleveland
                                 -----------------------------------------------
                                 Russell Cleveland
                                 President and CEO


                             RENAISSANCE CAPITAL GROWTH & INCOME FUND III, INC.

                             By:  Renaissance Capital Group, Inc.,
                                  Investment Adviser


                                   By: /s/ Russell Cleveland
                                       -----------------------------------------
                                       Russell Cleveland,
                                       President and CEO


                             AGENT:

                             RENAISSANCE CAPITAL GROUP, INC.


                             By: /s/ Russell Cleveland
                                 -----------------------------------------------
                                 Russell Cleveland,
                                 President and CEO


                                       8
<PAGE>


                                   Schedule 1

<TABLE>
<CAPTION>

Borrower's patents

Patent # Title
<S>               <C>
5,013,943         Single ended sense amplifier with improved data recall for variable bit line current
5,055,720         Current mirror sense amplifier with reduced current consumption and enhanced output signal
5,065,362         Non-volatile RAM with integrated compact static RAM load configuration
5,309,047         Differential sense amplifier with cross connected reference circuits
5,563,839         Semiconductor memory device having a sleep mode
5,602,776         Non-Volatile, static random access memory with current limiting
5,828,599         Memory with electrically erasable and programmable redundancy
6,026,018         Non-volatile, static random access memory with store disturb immunity
6,097,629         Non-volatile, static random access memory with high speed store capability
6,163,568         Broadband, low power FM/FSK transceiver for wireless communications systems
6,343,071         Wireless desktop area network system
</TABLE>


Borrower has not filed any trademark or copyright  application  with any federal
or state trademark or copyright authority.