<PAGE>
                                                                   EXHIBIT 10.6

                 ---------------------------------------------


                          AMENDMENT TO LOAN AGREEMENT


BORROWERS:          CYMER, INC. AND CYMER JAPAN, INC.

DATED AS OF:        FEBRUARY 4, 1999


     THIS AMENDMENT TO LOAN AGREEMENT is entered into between SILICON VALLEY
BANK ("Silicon") and BANK OF HAWAII ("BOH"), on the one side, Cymer, Inc.
("Cymer") and Cymer Japan, Inc. ("Cymer Japan") on the other side.

     The Parties agree to amend the Loan Agreement between them, dated
December 8, 1997, as amended from time to time (the "Loan Agreement"), as
follows, effective as of the date hereof, unless otherwise stated below.
(Capitalized terms used but not defined in this Amendment shall have the
meanings set forth in the Loan Agreement.)

     1.     REVISED DEFINITIONS. Section 1.1 of the Loan Agreement is hereby
amended by replacing the definitions of "Committed Revolving Line," "Optional
Currency Rate," "LIBOR Based Rate" and "Revolving Maturity Date" with the
following definitions, respectively, PROVIDED that the date of effectiveness
of the amendment to Optional Currency Rate shall be as of February 9, 1999:

     "COMMITTED REVOLVING LINE" means Thirty Million Dollars ($30,000,000).

     "OPTIONAL CURRENCY RATE" means, with respect to any Interest Period
     regarding the Optional Currency Advance, 200 basis points PLUS the
     rate per annum equal to the Euro Yen Tokyo Inter-bank Offered Rate
     as announced by the Federation of Bankers Association of Japan two
     (2) Business Days before the first day of such Interest Period for
     a period approximately equal to such Interest Period and in an
     amount approximately equal to such Advance, or, in the absence
     thereof, the rate per annum determined by the Servicing Agent to be
     the per annum rate or interest at which deposits in Japanese Yen
     are offered to the Servicing Agent in the Tokyo inter-bank market
     in which the Servicing Agent customarily participates at 11:00 A.M.
     (local time in such interbank market) two (2) Business Days before
     the first day of such Interest Period for a period approximately
     equal to such Interest Period and in an amount approximately equal
     to the amount of such Advance.

     "LIBOR BASED RATE" means the LIBOR Interest Rate for an identified
     Interest Period plus 200 basis points.

     "REVOLVING MATURITY DATE" means February 3, 2000, as such date may
     from time to time be extended by lenders in their sole discretion
     pursuant to this agreement."

     2.     NEW DEFINITION. Section 1.1 of the Loan Agreement is hereby
amended by adding the definition of "February 1999 Amendment" thereto:

     "FEBRUARY 1999 AMENDMENT" means the Amendment to Loan Agreement
     dated February 4, 1999 between Silicon and BOH, on the one side,
     and Cymer and Cymer Japan, on the other side."

     3.     SECTION 2.1.1A. Section 2.1.1A of the Loan Agreement is hereby to
read as follows:

                                    -1-

<PAGE>

        SILICON VALLEY BANK                  AMENDMENT TO LOAN AGREEMENT
        -----------------------------------------------------------------

     "2.1.1.A  OPTIONAL CURRENCY ADVANCE.

     Substantially concurrently with the execution and delivery of the
     April 1998 Amendment, an Optional Currency Advance in the Dollar
     Equivalent of Fifteen Million Dollars ($15,000,000) shall be made
     to Cymer Japan, PROVIDED, HOWEVER, that it is understood the Dollar
     Equivalent of the principal amount of such Optional Currency
     Advance will fluctuate over time due to currency variations,
     PROVIDED, FURTHER, in connection with the February 1999 Amendment
     it is the intention of the Lenders to have increased the
     availability of the Dollar Equivalent of the Optional Currency
     Advance by $5,000,000 to the above-referenced $15,000,000 amount,
     even though, due to the currency fluctuations, the Dollar
     Equivalent of the Optional Currency Advance in effect prior to the
     February 1999 Amendment was in excess of the then stated credit
     limit amount of the Optional Currency Advance. Accordingly, the
     parties hereto hereby agree that if the Dollar Equivalent of the
     principal amount of such Optional Currency Advance exceeds Fifteen
     Million Dollars ($15,000,000) at any time, including, without
     limitation, upon the making of the incremental $5,000,000 Optional
     Currency Advance in connection with the February 1999 Amendment,
     such an occurrence shall not constitute an Event of Default nor
     prevent the making of such incremental advance as contemplated in
     the previous sentence, as long as the aggregate principal amount of
     all Revolving Advances together with the Dollar Equivalent of the
     aggregate principal amount of the Optional Currency Advance does
     not exceed Twenty Million Dollars ($20,000,000) after the making of
     any and all Advances. The Optional Currency Advance shall be made
     by each of the Lenders in an amount up to its respective Commitment
     Percentage of Revolving Advances, and BOH shall be the agent for
     both Lenders in connection with the making of such Advance.
     Repayments of the Optional Currency Advance made in such Optional
     Currency shall be made only at the branch of BOH in the country of
     such Optional Currency."

     4.     FOREIGN EXCHANGE RESERVE MODIFICATION. The "Foreign Exchange
Reserve" is hereby amended to be the following amounts on any given day (the
"Determination Date"); on all outstanding Exchange Contracts on which
delivery is to be effected or settlement allowed, 20% of the gross amount of
the Exchange Contracts. Further, the "Contract Limit" as set forth in Section
2.1.3(a) of the Loan Agreement is hereby amended to be $50,000,000.

     5.     NO UNUSED LINE FEE. Section 2.5.4 of the Loan Agreement regarding
an unused line fee payable by the Borrower is hereby deleted in its entirety.

     6.     MODIFICATION FEE. Borrower shall to the Lenders a fee of $12,500
in connection herewith, which shall be addition to interest and to all other
amounts payable under the Loan Agreement and which shall not be refundable.

     7.     FINANCIAL COVENANTS. Section 6.8 of the Loan Agreement is hereby
amended, respectively, to read as follows:

     "6.8 TANGIBLE NET WORTH. Cymer, Inc. shall maintain, on a
     consolidated basis, as of the last day of each calendar quarter
     a Tangible Net Worth of not less than Two Hundred Sixty Million
     Dollars ($260,000,000) PLUS Fifty Percent (50%) of Borrower's
     quarterly net income (after taxes) (with no subtraction for losses)
     LESS the amount of the Borrower's treasury shares up to $25,000,000
     for such shares that are purchased on and after December 31, 1998."

     8.     QUICK RATIO. The Loan Agreement is hereby amended to add a new
section entitled "6.9A Quick Ratio" that replaces Section 6.9 of the Loan
Agreement, and which shall read as follows:

                                  -2-

<PAGE>

        SILICON VALLEY BANK                  AMENDMENT TO LOAN AGREEMENT
        -----------------------------------------------------------------

     "6.9A QUICK RATIO. Cymer, Inc. shall maintain, on a consolidated
     basis, as of the last day of each calendar quarter, a ratio of
     Quick Assets to Current Liabilities of at least 2.00 to 1.0. For
     purposes of the foregoing, however, Current Liabilities shall not
     include deferred revenues. "Quick Assets" means, as of any
     applicable date, the consolidated cash, cash equivalents, accounts
     receivable and long term marketable securities of Borrower
     determined in accordance with GAAP. "Current Liabilities" means, as
     of any applicable date, all amounts that should, in accordance with
     GAAP, be included as current liabilities on the consolidated
     balance sheet of Borrower and its Subsidiaries, as at such date,
     plus, to the extent not already included therein, all outstanding
     credit extensions made under this Agreement, including all
     Indebtedness that is payable upon demand or within one year from
     the date of determination thereof unless such Indebtedness is
     renewable or extendable at the option of Borrower or any Subsidiary
     to a date more than one year from the date of determination, but
     excluding Subordinated Debt." In connection with the calculation of
     the Quick Ratio, the assets and liabilities of Borrower associated
     with the Foreign Exchange Contracts shall be included therein on a
     Net Basis.

     9.     PROFITABILITY. The Loan Agreement is hereby amended to add a new
section entitled "6.9B Profitability" that immediately follows Section 6.9A
of the Loan Agreement, and which shall read as follows:

     6.9B   PROFITABILITY. Other than as stated below, Borrower shall not
     incur a loss (after taxes) in any fiscal quarter in excess of
     $5,000,000, PROVIDED, HOWEVER, regardless of the foregoing, Borrower
     shall not incur cumulative losses (after taxes) during the period of
     Borrower's 1999 fiscal year in excess of $12,500,000. Further, for the
     fiscal quarter ending December 31, 1999 and in each fiscal quarter
     thereafter, Borrower shall not incur any losses (after taxes).

     10.     SECTION 8.2.1 MODIFICATION. Section 3.2.1 of the Loan Agreement is
hereby amended in its entirety to read as follows:

     "8.2.1 If such Borrower fails to perform any obligation under Sections
     6.7, 6.8, 6.9A, 6.9B, 6.10, 6.11 or 6.12 or violates any of the
     covenants contained in Article 7 of this Agreement, or"


                   [text continues on the following page]

                                  -3-
<PAGE>

             SILICON VALLEY BANK                 AMENDMENT TO LOAN AGREEMENT
        -----------------------------------------------------------------------

     11.    SCHEDULE TO LOAN AGREEMENT. The Schedule to the Loan Agreement is
hereby amended to read as follows:


                                  "SCHEDULE

                                      TO

                          LOAN AND SECURITY AGREEMENT

                                  COMMITMENTS"


                           COMMITTED REVOLVING LINE;

<TABLE>
<CAPTION>

LENDER                             COMMITMENT            COMMITMENT PERCENTAGE
<S>                                <C>                   <C>
SILICON VALLEY BANK                $15,000,000                    50%
BANK OF HAWAII                     $15,000,000                    50%

</TABLE>


     12.    REPRESENTATIONS TRUE. Borrower represents and warrants to Bank that
all representations and warranties set forth in the Loan Agreement are true
and correct.

     13.    GENERAL PROVISIONS. This Amendment, the Loan Agreement, any prior
written amendments to the Loan Agreement signed by Bank and the Borrower, and
the other written documents and agreements between Bank and the Borrower set
forth in full all of the representations and agreements of the parties with
respect to the subject matter hereof and supersede all prior discussions,
representations, agreements and understandings between the parties with
respect to the subject hereof. Except as herein expressly amended, all of the
terms and provisions of the Loan Agreement, and all other documents and
agreements between Bank and the Borrower shall continue in full force and
effect and the same are hereby ratified and

                                     -4-
<PAGE>

             SILICON VALLEY BANK                 AMENDMENT TO LOAN AGREEMENT
        -----------------------------------------------------------------------

confirmed. This Agreement and Consent may be executed in any number of
counterparts, which when taken together shall constitute one and the same
agreement.


CYMER, INC.                            SILICON VALLEY BANK

BY  /s/ Robert P. Akins                BY  /s/ John W. Otterson
  --------------------------------       ------------------------------------
    PRESIDENT OR VICE PRESIDENT        TITLE    SENIOR VICE PRESIDENT
                                            ---------------------------------

CYMER JAPAN, INC.                      BANK OF HAWAII

BY  /s/ William A. Angus, III          BY
  --------------------------------       ------------------------------------
    PRESIDENT OR VICE PRESIDENT        TITLE
                                            ---------------------------------

                                     -5-

















<PAGE>

                 ---------------------------------------------


                          AMENDMENT TO LOAN AGREEMENT


BORROWERS:          CYMER, INC.
                    CYMER JAPAN, INC.

DATED AS OF:        SEPTEMBER 22, 1999


     THIS AMENDMENT TO LOAN AGREEMENT is entered into between SILICON VALLEY
BANK ("Silicon") and BANK OF HAWAII ("BOH"), on the one side, Cymer, Inc.
("Cymer") and Cymer Japan, Inc. ("Cymer Japan") on the other side.

     The Parties agree to amend the Loan Agreement between them, dated
December 8, 1997, as amended from time to time (the "Loan Agreement"), as
follows, effective as of the date hereof, unless otherwise stated below.
(Capitalized terms used but not defined in this Amendment shall have the
meanings set forth in the Loan Agreement.)

     1.     MODIFICATION of Section 2.1.1 sECTION 2.1.1 of the Loan Agreement is
hereby in its entirety to read as follows:

            "2.1.1 THE REVOLVING ADVANCES. Subject to and upon the terms and
     conditions hereof, and in reliance upon the representations and
     warranties of the Borrowers set forth herein, each Lender severally
     agrees to make its Commitment Percentage of Revolving Advances to Cymer
     up to the aggregate amount of $3,500,000 for both Lenders from time to
     time until the close of business on the Revolving Maturity Date, in such
     sums as Cymer may request, PROVIDED that the aggregate principal amount
     of all Revolving Advances and the Dollar Equivalent of the Optional
     Currency Advances at any one time outstanding shall not exceed the
     Committed Revolving Time minus the Foreign Exchange Reserve. Subject to
     the terms and conditions of this Agreement and in reliance upon the
     representations and warranties set forth herein, amounts borrowed
     pursuant to this Section 2.1.1 may be repaid and reborrowed at any time
     during the term of this Agreement. The minimum amount of a Prime Based
     Rate Revolving Advance is $25,000. The minimum amount of a LIBOR Based
     Rate Revolving Advance is $500,000, and loan amounts greater than such
     sum are required to be in integral multiples of $50,000 in excess
     thereof.

            Cymer promises to pay to Servicing Agent for the account of each
     Lender, in lawful money of the United States of America, the aggregate
     unpaid principal amount of all Revolving Advances made by Servicing
     Agent and Lenders to Borrower. Borrower shall also pay interest on the
     aggregate unpaid principal amount of such Advances at the rates and in
     accordance with the terms hereof.

            The Committed Revolving Line shall terminate on the Revolving
     Maturity Date, at which time all Revolving Advances under this Section
     2.1.1, all Optional Currency Advances, and other amounts due under this
     Agreement (except as otherwise expressly specified herein) shall be
     immediately due and payable."

     2.     MODIFICATION OF FOREIGN EXCHANGE CONTRACT LIMIT. The "Contract
Limit", as set forth in Section 2.1.3(a) of the Loan Agreement, is hereby
amended to be $57,500,000.

                                   -1-
<PAGE>
               Silicon Valley Bank           Amendment to Loan Agreement
            ---------------------------------------------------------------


     3.     REPRESENTATIONS TRUE. Borrower represents and warrants to Bank
that all representations and warranties set forth in the Loan Agreement are
true and correct.

     4.     GENERAL PROVISIONS. This Amendment, the Loan Agreement, any prior
written amendents to the Loan Agreement signed by Bank and the Borrower, and
the other written documents and agreements between Bank and the Borrower set
forth in full all of the representations and agreements of the parties with
respect to the subject matter hereof and supersede all prior discussions,
representation, agreements and understandings between the parties with repect
to the subject hereof. Except as herein expressly amended, all of the terms
and provisions of the Loan Agreement, and all other documents and agreements
between Bank and Borrower shall continue in full force and effect and the
same are hereby ratified and confirmed. This Agreement and Consent may be
executed in any number of counterparts, which when taken together shall
constitute one and the same agreement.



CYMER, INC.                                SILICON VALLEY BANK

By /s/ Robert P. Akins                     By /s/ John W. Otterson
   ---------------------------                -----------------------------
   President or Vice President             Title  Senior Vice President
                                                -----------------------------


CYMER JAPAN, INC.                          BANK OF HAWAII

By /s/ William A. Angus, III               By /s/ Scott R. Nahme
   ----------------------------               ------------------------------
   President or Vice President             Title  Vice President
                                                ------------------------------

                                  -2-

<PAGE>

          ---------------------------------------------------------

                          AMENDMENT TO LOAN AGREEMENT

BORROWERS:     CYMER, INC. AND CYMER JAPAN, INC.

DATED AS OF:   FEBRUARY 4, 2000

     THIS AMENDMENT TO LOAN AGREEMENT is entered into between SILICON VALLEY
BANK ("Silicon") and BANK OF HAWAII ("BOH"), on the one side, Cymer, Inc.
("Cymer") and Cymer Japan, Inc. ("Cymer Japan"), on the other side.

     The Parties agree to amend the Loan Agreement between them, dated
December 8, 1997, as amended from time to time (the "Loan Agreement"), as
follows, effective as of the date hereof, (Capitalized terms used but not
defined in this Amendment, shall have the meanings set forth in the Loan
Agreement.)

     1.     REVISED DEFINITIONS. Section  1.1 of the Loan Agreement is hereby
amended by replacing the definitions of "Committed Revolving Line" and
"Revolving Maturity Date" with the following definitions, respectively:

     "COMMITTED REVOLVING LINE" means Forty Million Dollars ($40,000,000).

     "REVOLVING MATURITY DATE" means February 3, 2001, as such date may
     from time to time be extended by lenders in their sole discretion
     pursuant to this agreement."

     2.     MODIFICATION OF SECTION 2.1.1. Section 2.1.1 of the Loan
Agreement is hereby deleted in its entirety and replaced with the following:

          "2.1.1 OPTIONAL CURRENCY REVOLVING ADVANCES. Subject to and
     upon the terms and conditions hereof, and in reliance upon the
     representations and warranties of the Borrowers set forth herein,
     each Lender severally agrees to make its Commitment Percentage of
     Revolving Advances consisting of Optional Currency Advances to
     Cymer up to the aggregate amount of the Dollar Equivalent of
     $20,000,000 for both Lenders from time to time until the close of
     business on the Revolving Maturity Date, in such sums as Cymer may
     request, PROVIDED, FURTHER, that the aggregate principal amount of
     the Dollar Equivalent of the Optional Currency Advances at any one
     time outstanding shall not exceed the Committed Revolving Line
     minus the Foreign Exchange Reserve.

     Each Optional Currency Advance shall be made by each of the Lenders
     in an amount up to its respective Commitment Percentage of
     Revolving Advances, and BOH shall be the agent for both Lenders in
     connection with the making of such Advance. Repayments of the
     Optional Currency Advance are to made in such Optional Currency and
     shall be made only at the branch of BOH in the country of such
     Optional Currency.

     All Optional Currency Advances shall bear interest on the average
     Daily Balance thereof at the Optional Currency Rate. All interest
     relating to the Optional Currency Rate chargeable under the Loan
     Documents shall be computed on the basis of a three hundred

                                     -1-
<PAGE>

            SILICON VALLEY BANK            AMENDMENT TO LOAN AGREEMENT
        -----------------------------------------------------------------

     sixty (360) day year for the actual number of days elapsed, except
     where the law or commercial custom in the country of the Optional
     Currency requires otherwise.

     The Committed Revolving Line shall terminate on the Revolving
     Maturity Date, at which time all Optional Currency Advances, and
     all other amounts due under this Agreement (except as otherwise
     expressly specified herein) shall be immediately due and payable."

     3.     SECTION 2.1.1A. Section 2.1.1A of the Loan Agreement is hereby
deleted on its entirety and shall be amended to read as follows:

     "2.1.1.A [Reserved]

     4.  REVISED SECTION 2.1.3(a) Subsection (a) of 2.1.3 of the Loan
Agreement is hereby amended to read as follows:

     "(a)     Subject to the terms of this Agreement, either Borrower,
     on a joint basis, may enter into foreign exchange contracts (the
     "Exchange Contracts") not to exceed an aggregate Dollar Equivalent
     amount of $100,000,000 (the "Contract Limit"), pursuant to which
     Lenders shall sell to or purchase from Borrower foreign currency on
     a spot or future basis. A Borrower shall not request any Exchange
     Contracts at any time a Default or an Event of Default has occurred
     and is continuing. All Exchange Contracts must provide for delivery
     of settlement on or before 365 days past the then applicable
     Revolving Maturity Date. The amount available under the Committed
     Revolving Line at any time shall be reduced by the following amounts
     (the "Foreign Exchange Reserve") on any given day (the "Determination
     Date"); on all outstanding Exchange Contracts on which delivery is to be
     effected or settlement allowed, 20% of the gross amount of the
     Exchange Contracts. If on the Revolving Maturity Date, or on any
     earlier effective date of termination, there are any outstanding
     Exchange Contracts, then on such date Borrower shall provide cash
     collateral in an amount equal to the Foreign Exchange Reserve, to
     secure all of the Obligations relating to said Exchange Contracts
     on the Lenders' standard form cash pledge agreement."

     5.     TANGIBLE NET WORTH FINANCIAL COVENANT. Section 6.8 of the Loan
Agreement is hereby amended to read as follows:

     "6.8     TANGIBLE NET WORTH. Cymer, Inc. shall maintain, on a
     consolidated basis, as of the last day of each calendar quarter, a
     Tangible Net Worth of not less than Two Hundred Seventy-Five
     Million Dollars ($275,000,000) PLUS Fifty Percent (50%) of
     Borrower's quarterly net income (after taxes) (with no subtraction
     for losses) LESS the amount of the Borrower's treasury shares up to
     $25,000,000 for such shares that are purchased on and after
     December 31, 1998."

     6.     PROFITABILITY. Section 6.9B of the Loan Agreement is hereby
amended to read as follows:

     "6.9B     PROFITABILITY. Borrower shall not incur a loss (after
     taxes) in any fiscal quarter.

                                     -2-
<PAGE>

             SILICON VALLEY BANK                 AMENDMENT TO LOAN AGREEMENT
        -----------------------------------------------------------------------

                        [text continues on the next page]












                                     -3-
<PAGE>

             SILICON VALLEY BANK                 AMENDMENT TO LOAN AGREEMENT
        -----------------------------------------------------------------------

     7.  SCHEDULE TO LOAN AGREEMENT. The Schedule to the Loan Agreement is
hereby amended to read as follows:


                                  "SCHEDULE

                                      TO

                          LOAN AND SECURITY AGREEMENT

                                  COMMITMENTS"


                           COMMITTED REVOLVING LINE:

<TABLE>
<CAPTION>

LENDER                             COMMITMENT            COMMITMENT PERCENTAGE
<S>                                <C>                   <C>
SILICON VALLEY BANK                $20,000,000                    50%
BANK OF HAWAII                     $20,000,000                    50%

</TABLE>

     8.     MODIFICATION FEE. Borrower shall to the Lenders a fee of $100,000
in connection herewith, which shall be in addition to interest and to all
other amounts payable under the Loan Agreement and which shall not be
refundable.

     9.     REPRESENTATIONS TRUE. Borrower represents and warrants to Bank
that all representations and warranties set forth in the Loan Agreement are
true and correct.

     10.    GENERAL PROVISIONS.  This Amendment, the Loan Agreement, any
prior written amendments to the Loan Agreement signed by Bank and Borrower,
and the other written documents and agreements between Bank and Borrower set
forth in full all of the representations and agreements of the parties with
respect to the subject matter hereof and supersede all prior discussions,
representations, agreements and understandings between the parties with
respect to the subject hereof. Except as herein expressly amended, all of the
terms and provisions of the Loan Agreement, and all other documents and
agreements between Bank

                                     -4-
<PAGE>

             SILICON VALLEY BANK                 AMENDMENT TO LOAN AGREEMENT
        -----------------------------------------------------------------------

and the Borrower shall continue in full force and effect and the same are
hereby ratified and confirmed. This Agreement and Consent may be executed in
any number of counterparts, which when taken together shall constitute one
and the same agreement.



CYMER, INC.                            SILICON VALLEY BANK

BY  /s/ Robert P. Akins                BY  /s/ Raquel Cunningham
  --------------------------------       ------------------------------------
    PRESIDENT OR VICE PRESIDENT        TITLE   VICE PRESIDENT
                                            ---------------------------------

CYMER JAPAN, INC.                      BANK OF HAWAII

BY  /s/ William A. Angus, III          BY  /s/ Scott R. Nahme
  --------------------------------       ------------------------------------
    PRESIDENT OR VICE PRESIDENT        TITLE  VICE PRESIDENT
                                            ---------------------------------

                                     -5-