EMPLOYEE MATTERS AGREEMENT

EMPLOYEE MATTERS AGREEMENT (this “ Agreement ”) dated as of December 21, 2006 by and between ACACIA RESEARCH CORPORATION, a Delaware corporation (“ Acacia ”), and COMBIMATRIX CORPORATION, a Delaware corporation (“ CombiMatrix ”), a wholly owned subsidiary of Acacia.

WHEREAS, the Acacia Board of Directors has determined that it is appropriate and desirable, subject to the terms and conditions set forth in the Distribution Agreement by and between Acacia and CombiMatrix dated as of the date hereof (the “ Distribution Agreement ”), to distribute all outstanding shares of CombiMatrix Common Stock on a pro rata basis to the holders of CombiMatrix Tracking Stock (the “ Distribution ”);

WHEREAS, in connection with the Distribution, Acacia and CombiMatrix have determined that it is appropriate and desirable to provide for the allocation of certain other matters relating to employees, employee benefit plans and compensation arrangements;

NOW, THEREFORE, in consideration of the premises and the respective agreements and covenants contained in this Agreement, the parties hereby agree as follows:

Section 1.01    General . The following terms have the following meanings (in each case, such meanings to be equally applicable to both the singular and plural forms of the terms defined):

“ Acacia ” has the meaning set forth in the preamble.

“ Acacia Group ” means Acacia Research Corporation and all of its Subsidiaries, excluding any entities in the CombiMatrix Group.

“ Acacia Participant ” means any individual who, immediately after the Time of Distribution, is (i) an Active Acacia Employee, (ii) a Former Acacia Employee or (iii) a beneficiary of either of the foregoing.

“ Acacia Savings Plan ” means the Acacia Technologies Services Corporation 401(k) Savings Plan, including all amendments thereto through the Distribution Date.

“ Acacia Welfare Plans ” mean the Welfare Plans maintained by Acacia and its Subsidiaries (excluding members of the CombiMatrix Group) immediately prior to the Time of Distribution.

“ Active Acacia Employee ” means any individual who, immediately after the Time of Distribution, will be employed by a member of the Acacia Group pursuant to Section 2.01(b).

“ Active CombiMatrix Employee ” means any individual who, immediately after the Time of Distribution, will be employed by a member of the CombiMatrix Group pursuant to Section 2.01(a).

“ Agreement ” has the meaning set forth in the preamble.

“ CombiMatrix ” has the meaning set forth in the preamble.

“ CombiMatrix Group ” means CombiMatrix and all of its Subsidiaries.

“ CombiMatrix Participant ” means any individual who, immediately after the Time of Distribution, is (i) an Active CombiMatrix Employee, (ii) a Former CombiMatrix Employee or (iii) a beneficiary of either of the foregoing.

“ CombiMatrix Savings Plan ” means the CombiMatrix Corporation 401(k) Savings Plan, including all amendments thereto through the Distribution Date.

“CombiMatrix Tracking Stock ” means the Acacia common stock designated for its CombiMatrix Subsidiary prior to the Time of Distribution and also referred to as Acacia Research - CombiMatrix stock.

“ CombiMatrix Welfare Plans ” mean the Welfare Plans maintained by the CombiMatrix Group immediately prior to the Time of Distribution.

“ Distribution ” has the meaning set forth in the recitals.

“ Distribution Agreement ” has the meaning set forth in the recitals.

“ ERISA ” means the Employee Retirement Income Security Act of 1974, as amended, or any successor legislation.

“ Former Acacia Employee ” means any Pre-Distribution Group Employee who is not, immediately after the Time of Distribution, an Active Acacia Employee or an Active CombiMatrix Employee, and whose most recent active employment was with the Acacia Group.

“ Former CombiMatrix Employee ” means any Pre-Distribution Group Employee who is not, immediately after the Time of Distribution, an Active CombiMatrix Employee or an Active Acacia Employee, and whose most recent active employment was with the CombiMatrix Group.

“ Incentive Compensation Plan ” means any plan providing for bonuses or other incentive compensation other than a plan that provides for equity compensation (such as stock options).

“ Liabilities ” has the meaning set forth in the Distribution Agreement.

“ Pre-Distribution Group ” has the meaning set forth in the Distribution Agreement.

“ Pre-Distribution Group Employee ” means any individual who was, at any time prior to the Time of Distribution, employed by Acacia, CombiMatrix or any other member of the Pre-Distribution Group.

“ Separation Agreement ” has the meaning set forth in the Distribution Agreement.

“ Subsidiary ” means, with respect to any person, any corporation or other organization, whether incorporated or unincorporated, of which such person or any Subsidiaries of such person controls or owns, directly or indirectly, more than 50% of the stock or other equity interest, or more than 50% of the voting power entitled to vote on the election of members to the board of directors or similar governing body. Notwithstanding the foregoing, the term “Subsidiary” shall also mean, with respect to Combimatrix, the following entities: (i) Leuchemix, a California corporation, and (ii) CombiMatrix K.K., a Japanese corporation.

“ Time of Distribution ” means the effective date of the Distribution.

“ Welfare Plan ” means an employee welfare benefit plan as defined in Section 3(1) of ERISA, including cafeteria, medical, vision, dental and other health plans, retiree health plans, life insurance plans, retiree life insurance plans, accidental death and dismemberment plans, long-term disability plans and severance pay plans, dependent care reimbursement plans, health care reimbursement plans and any other employee welfare benefit and fringe benefit arrangements.

Section 2.01    Employees .

(a)    Each individual who is currently employed by a member of the CombiMatrix Group immediately prior to the Time of Distribution, including those individuals who are actively employed or on lay-off, leave, short-term or long-term disability or other permitted absence from employment will continue to be employed by a member of the CombiMatrix Group immediately after the Time of Distribution and will be an Active CombiMatrix Employee.

(b)    Each individual (other than those employed by the CombiMatrix Group immediately prior to the Time of Distribution) who is employed by the Acacia Group immediately prior to the Time of Distribution (including those who are actively employed or on lay-off, leave, short-term or long-term disability or other permitted absence from employment) will be or will continue to be employed by a member of the Acacia Group immediately after the Time of Distribution and will be an Active Acacia Employee.

(c)    Effective as of the Time of Distribution, (i) for immigration purposes CombiMatrix will be the successor-in-interest to any and all pending or approved visa petitions (whether with the U.S. Bureau of Citizenship and Immigration Services or U.S. Department of Labor), including pending or completed Labor Condition Applications, made by Acacia or any of its Subsidiaries with respect to any Active CombiMatrix Employees, and CombiMatrix will adopt and accept all representations made by Acacia in any of these petitions and applications, (ii) CombiMatrix will adopt any Labor Condition Application included in the “Public Access Folders” for Active CombiMatrix Employees who have H-1B visas, and (iii) CombiMatrix will adopt any existing I-9 certifications of Acacia and its Subsidiaries with respect to Active CombiMatrix Employees.

(d)    Nothing contained in this Section 2.01 is intended to confer upon any employee of the CombiMatrix Group or the Acacia Group any right to continued employment after the Time of Distribution.

Section 2.02    Non-Solicitation of Employees . Without the express written agreement of both the Chief Executive Officer of Acacia and the Chief Executive Officer of CombiMatrix:

(a)    Acacia agrees not to (and to cause the other members of the Acacia Group not to) solicit, recruit or hire, directly or indirectly (including by contracting with or through an independent contractor, consultant or other third party) any employee of, or individual providing consulting services to, CombiMatrix or any other member of the CombiMatrix Group until eighteen (18) months after the Time of Distribution or until six (6) months after such employee’s employment with, or such individual’s provision of consulting services to, CombiMatrix or any other member of the CombiMatrix Group terminates, whichever occurs first;

(b)    CombiMatrix agrees not to (and to cause the other members of the CombiMatrix Group not to) solicit, recruit or hire, directly or indirectly (including by contracting with or through an independent, contractor, consultant or other third party) any employee of, or individual providing consulting services to, Acacia or any other member of the Acacia Group until 18 months after the Time of Distribution or until six months after such employee’s employment with, or such individual’s provision of consulting services to, Acacia or any other member of the Acacia Group terminates, whichever occurs first; and

(c)    Notwithstanding the foregoing (but subject to the restriction on hiring), such prohibitions on solicitation do not restrict general recruitment efforts carried out through a public or general solicitation.

As of the Time of Distribution, CombiMatrix maintains the CombiMatrix Retirement Savings Plan, in which employees of the CombiMatrix Group are eligible to participate. As of the Time of Distribution, the Acacia Group maintains the Acacia Retirement Savings Plan, in which employees of the Acacia Group are eligible to participate. No changes to the current operation of and no transfers between the CombiMatrix Retirement Savings Plan and the Acacia Retirement Savings Plan shall be required by this Transaction and both plans shall continue in operation in accordance with their terms.

Acacia and CombiMatrix will take all action necessary or appropriate so that the Distribution will be treated as a “change in control” under each Acacia equity compensation plan where options to purchase shares of CombiMatrix Tracking Stock (each an “ Option ”) are outstanding. Each such Option that is outstanding immediately prior to the Time of Distribution will be fully vested immediately prior to the Time of Distribution and contingent upon the Distribution and, except as otherwise specified in this paragraph, will terminate at the Time of Distribution. Acacia and CombiMatrix will provide written notice to the holders of the Options that the Options are vesting fully and terminating at the Time of Distribution. To the extent that an Option cannot be terminated as of the Time of Distribution and for any Option held by a person who is no longer an employee of either the Acacia Group or the CombiMatrix Group, such Option shall be assumed by the CombiMatrix Group at the Time of Distribution (an “ Assumed Option ”) and will be appropriately and equitably adjusted as the number of shares purchasable under such Assumed Option and the per share exercise price for any differences in the capitalization of CombiMatrix in comparison with Acacia with respect to the Acacia-CombiMatrix Stock. Each such Assumed Option will otherwise have the same terms and conditions as those in effect immediately prior to the assumption.

Section 5.01    Welfare Plans .

(a)    Prior to the Time of Distribution, Acacia and CombiMatrix will take all action necessary or appropriate to create a separate Welfare Plan for each of the CombiMatrix Group and the Acacia Group to the extent that the Acacia Group and the CombiMatrix Group participate in or sponsor the same Welfare Plan as of the date of this Agreement.

(b)    As of the Time of Distribution, CombiMatrix will maintain Welfare Plans and other employee welfare benefit and fringe benefit arrangements (collectively, “ CombiMatrix Welfare Plans ”) for CombiMatrix Participants. As of the Time of Distribution, the Acacia Group will maintain Welfare Plans and other employee welfare benefit and fringe benefit arrangements (collectively, “ Acacia Welfare Plans ”) for Acacia Participants. Except as provided in Section 5.01(a), no changes to the operation of the CombiMatrix Welfare Plans and the Acacia Welfare Plans shall be required in connection with the Distribution and the CombiMatrix Welfare Plans and the Acacia Welfare Plans shall continue in operation in accordance with their terms.

(c)    As of the Time of Distribution, CombiMatrix (and, if appropriate, the correct member of the CombiMatrix Group) will have established, and will cover Active CombiMatrix Employees under, policies relating to vacation days and personal and sick days. As of the Time of Distribution, CombiMatrix (and, if appropriate, the correct member of the CombiMatrix Group) will credit each Active CombiMatrix Employee with the unused vacation days and personal and sick days accrued by such employee through the Time of Distribution in accordance with the policies relating to vacation days and personal and sick days applicable to such employ