BUSINESS COMBINATION	3 Months Ended
Mar. 27, 2016
Business Combinations [Abstract]
Business Combination	BUSINESS COMBINATION Agreement and Plan of Merger On December 1, 2015, Mattson entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Beijing E-town Dragon Semiconductor Industry Investment Center (Limited Partnership), a People's Republic of China ("PRC") limited partnership (“Parent”), providing for the merger of Dragon Acquisition Sub, Inc., an indirect subsidiary of Parent (“Merger Sub”), with and into Mattson (the “Merger”), with Mattson surviving the Merger as a subsidiary of Parent (the “Surviving Corporation”). The Merger Agreement was unanimously approved by Mattson’s Board of Directors (the “Board”). On March 23, 2016, Mattson stockholders approved the adoption of the Merger Agreement by the affirmative vote of holders of a majority of the outstanding shares of the Company's Common Stock (the “Company Stockholder Approval”). Pursuant to the terms and subject to the conditions of the Merger Agreement, at the Effective Time (as defined in the Merger Agreement) of the Merger, each share of Mattson’s common stock, par value $0.001 per share (the “Company Common Stock”), outstanding immediately prior to the Effective Time will be cancelled and automatically converted into the right to receive $3.80 in cash, without interest (the “Merger Consideration”), excluding any shares owned by Mattson or any of its subsidiaries, or by Parent or Merger Sub or any of their respective wholly-owned subsidiaries (which will be cancelled) and any shares with respect to which appraisal rights have been properly exercised under Delaware law. Beijing E-Town International Investment & Development Co., Ltd., the parent company to Parent, has irrevocably and unconditionally guaranteed to the Company the due and punctual payment and performance of Parent’s and Merger Sub’s obligations under the Merger Agreement. At the Effective Time, each option to purchase shares of Company Common Stock (a “Company Option”) that is outstanding and either (i) vested as of the Effective Time or (ii) held by a non-employee member of the Board will be converted into the right to receive an amount in cash, without interest, equal to the product obtained by multiplying (a) the aggregate number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, by (b) the Merger Consideration, less the per share exercise price of such Company Option. At the Effective Time, each Company Option that is outstanding, unvested and held by an employee who continues employment with Parent or any of its subsidiaries (including the Surviving Corporation) after the Merger will either (i) conditioned upon receipt of an executed Award Surrender Agreement by the Company at least one business day prior to the Effective Time, be converted into the right to receive an amount in cash determined by multiplying (a) the aggregate number of shares of Company Common Stock represented by such Company Option immediately prior to the Effective Time by (b) the Merger Consideration, less the per share exercise price of such Company Option (the “Unvested Option Consideration”), or (ii) be assumed by the Surviving Corporation, on the same terms, conditions and vesting schedule applicable to such Company Option immediately prior to the Effective Time (an “Assumed Option”), except that (x) the number of shares of the Surviving Corporation’s common stock for which such Assumed Option will be exercisable will equal the product (rounded down to the next whole number, with no cash paid for any fractional share eliminated by such rounding) of the number of shares of Company Common Stock that were issuable upon exercise of such Company Option immediately prior to the Effective Time and the Exchange Ratio (as defined in the Merger Agreement) and (y) the per share exercise price for the shares of the Surviving Corporation’s common stock issuable upon exercise of such Assumed Option will equal the quotient (rounded up to the next whole cent) obtained by dividing the exercise price per share of such Company Option immediately prior to the Effective Time by the Exchange Ratio. The Unvested Option Consideration will be subject to the same vesting restrictions and continued service requirements applicable to such Company Option as are in effect immediately prior to the Effective Time, except that any portion of the Unvested Option Consideration remaining outstanding as of December 31, 2016 will accelerate in full and be paid as of such date. At the Effective Time, each Company restricted stock unit (a “Company RSU”) that is outstanding and either (i) vested as of the Effective Time or (ii) held by a non-employee member of the Board will be converted into the right to receive an amount in cash, without interest, equal to the product obtained by multiplying (a) the aggregate number of shares of Company Common Stock subject to such Company RSU immediately prior to the Effective Time by (b) the Merger Consideration. At the Effective Time, all other outstanding Company RSUs not described in the immediately preceding sentence will be converted into the right to receive an amount in cash, without interest, equal to the product obtained by multiplying (x) the aggregate number of shares of Company Common Stock subject to such Company RSU immediately prior to the Effective Time by (y) the Merger Consideration (the “Unvested RSU Consideration”). The Unvested RSU Consideration will be subject to the same vesting restrictions and continued service requirements applicable to such Company RSU immediately prior to the Effective Time. The obligations of the parties to consummate the Merger are subject to the satisfaction (or waiver, if applicable) of various customary conditions, including (i) filings and approvals with or by certain governmental authorities, including governmental authorities in the PRC and Taiwan, (ii) the absence of certain governmental orders prohibiting the Merger, (iii) the accuracy of the representations and warranties of each party contained in the Merger Agreement (subject to certain materiality qualifications) and (iv) each party’s compliance with or performance of the covenants and agreements in the Merger Agreement in all material respects. The Company has made customary representations, warranties and covenants in the Merger Agreement, including, among others, covenants (i) to conduct its business in all material respects in the ordinary course consistent with past practices during the period between the execution of the Merger Agreement and the closing of the Merger, and (ii) not to engage in specified types of transactions or take certain actions during the interim period unless consented to in writing by Parent. The Company is also subject to customary restrictions on its ability to solicit alternative acquisition proposals from third parties and to provide non-public information to, and participate in discussions and engage in negotiations with, third parties regarding alternative acquisition proposals, with customary exceptions for alternative acquisition proposals that the Board determines either constitute or could reasonably be expected to lead to a Superior Proposal (as defined in the Merger Agreement). Parent also has agreed to various covenants in the Merger Agreement, including, among others, covenants to take actions that may be necessary in order to obtain approval of the Merger with certain governmental authorities, subject to certain exceptions. The Merger Agreement contains certain termination rights for the Company and Parent. Upon termination of the Merger Agreement under specified circumstances, including in connection with the Company’s entry into a definitive agreement providing for the consummation of a Superior Proposal as permitted under the Merger Agreement, the Company will be required to pay Parent a termination fee of approximately $8.6 million. The Merger Agreement also provides that, upon termination of the Merger Agreement under specified circumstances, Parent will be required to pay the Company a termination fee of approximately $17.2 million (the “Parent Termination Fee”). The Parent Termination Fee will become payable from Parent to the Company if, subject to certain requirements and exceptions, the Merger Agreement is terminated by the Company in the event that (i) Parent and/or Merger Sub have breached or failed to perform any of its respective representations, warranties, covenants or other agreements set forth in the Merger Agreement such that the applicable closing conditions would not be satisfied or (ii) all of Parent’s conditions to closing are satisfied or waived and Parent has failed to consummate the Merger. During the three months ended March 27, 2016, we incurred $1.1 million in costs associated with the Merger Agreement, which was recorded as restructuring and other charges in our condensed consolidated statement of operations. Voting Agreement Concurrent with the execution of the Merger Agreement, the directors and certain executive officers of Mattson, in their capacities as holders of Company Common Stock or other equity interests of the Company, entered into a Voting Agreement with Parent (the “Voting Agreement”) pursuant to which each agreed, among other things, to (i) vote their Company Common Stock for the approval of the Merger Agreement and against any alternative proposal, and (ii) comply with certain restrictions on the disposition of their Company Common Stock, subject to the terms and conditions contained in the Voting Agreement. Each stockholder party to the Voting Agreement has granted an irrevocable proxy in favor of Parent to vote his or her shares or other equity interests as required by the terms of the Voting Agreement. The Voting Agreement will terminate upon the earlier of (a) the Effective Time, (b) the termination of the Voting Agreement by Parent, (c) the termination of the Merger Agreement in accordance with its terms or (d) a material modification, waiver or amendment of the Merger Agreement that (x) reduces the amount or changes the form of consideration to be paid to such stockholder or (y) creates any additional conditions to the consummation of the Merger (unless such stockholder consents to such modification, waiver or amendment).

BUSINESS COMBINATION

Agreement and Plan of Merger

On December 1, 2015, Mattson entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Beijing E-town Dragon Semiconductor Industry Investment Center (Limited Partnership), a People's Republic of China ("PRC") limited partnership (“Parent”), providing for the merger of Dragon Acquisition Sub, Inc., an indirect subsidiary of Parent (“Merger Sub”), with and into Mattson (the “Merger”), with Mattson surviving the Merger as a subsidiary of Parent (the “Surviving Corporation”). The Merger Agreement was unanimously approved by Mattson’s Board of Directors (the “Board”). On March 23, 2016, Mattson stockholders approved the adoption of the Merger Agreement by the affirmative vote of holders of a majority of the outstanding shares of the Company's Common Stock (the “Company Stockholder Approval”).

Pursuant to the terms and subject to the conditions of the Merger Agreement, at the Effective Time (as defined in the Merger Agreement) of the Merger, each share of Mattson’s common stock, par value $0.001 per share (the “Company Common Stock”), outstanding immediately prior to the Effective Time will be cancelled and automatically converted into the right to receive $3.80 in cash, without interest (the “Merger Consideration”), excluding any shares owned by Mattson or any of its subsidiaries, or by Parent or Merger Sub or any of their respective wholly-owned subsidiaries (which will be cancelled) and any shares with respect to which appraisal rights have been properly exercised under Delaware law. Beijing E-Town International Investment & Development Co., Ltd., the parent company to Parent, has irrevocably and unconditionally guaranteed to the Company the due and punctual payment and performance of Parent’s and Merger Sub’s obligations under the Merger Agreement.

At the Effective Time, each option to purchase shares of Company Common Stock (a “Company Option”) that is outstanding and either (i) vested as of the Effective Time or (ii) held by a non-employee member of the Board will be converted into the right to receive an amount in cash, without interest, equal to the product obtained by multiplying (a) the aggregate number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, by (b) the Merger Consideration, less the per share exercise price of such Company Option.

At the Effective Time, each Company Option that is outstanding, unvested and held by an employee who continues employment with Parent or any of its subsidiaries (including the Surviving Corporation) after the Merger will either (i) conditioned upon receipt of an executed Award Surrender Agreement by the Company at least one business day prior to the Effective Time, be converted into the right to receive an amount in cash determined by multiplying (a) the aggregate number of shares of Company Common Stock represented by such Company Option immediately prior to the Effective Time by (b) the Merger Consideration, less the per share exercise price of such Company Option (the “Unvested Option Consideration”), or (ii) be assumed by the Surviving Corporation, on the same terms, conditions and vesting schedule applicable to such Company Option immediately prior to the Effective Time (an “Assumed Option”), except that (x) the number of shares of the Surviving Corporation’s common stock for which such Assumed Option will be exercisable will equal the product (rounded down to the next whole number, with no cash paid for any fractional share eliminated by such rounding) of the number of shares of Company Common Stock that were issuable upon exercise of such Company Option immediately prior to the Effective Time and the Exchange Ratio (as defined in the Merger Agreement) and (y) the per share exercise price for the shares of the Surviving Corporation’s common stock issuable upon exercise of such Assumed Option will equal the quotient (rounded up to the next whole cent) obtained by dividing the exercise price per share of such Company Option immediately prior to the Effective Time by the Exchange Ratio. The Unvested Option Consideration will be subject to the same vesting restrictions and continued service requirements applicable to such Company Option as are in effect immediately prior to the Effective Time, except that any portion of the Unvested Option Consideration remaining outstanding as of December 31, 2016 will accelerate in full and be paid as of such date.

At the Effective Time, each Company restricted stock unit (a “Company RSU”) that is outstanding and either (i) vested as of the Effective Time or (ii) held by a non-employee member of the Board will be converted into the right to receive an amount in cash, without interest, equal to the product obtained by multiplying (a) the aggregate number of shares of Company Common Stock subject to such Company RSU immediately prior to the Effective Time by (b) the Merger Consideration. At the Effective Time, all other outstanding Company RSUs not described in the immediately preceding sentence will be converted into the right to receive an amount in cash, without interest, equal to the product obtained by multiplying (x) the aggregate number of shares of Company Common Stock subject to such Company RSU immediately prior to the Effective Time by (y) the Merger Consideration (the “Unvested RSU Consideration”). The Unvested RSU Consideration will be subject to the same vesting restrictions and continued service requirements applicable to such Company RSU immediately prior to the Effective Time.

The obligations of the parties to consummate the Merger are subject to the satisfaction (or waiver, if applicable) of various customary conditions, including (i) filings and approvals with or by certain governmental authorities, including governmental authorities in the PRC and Taiwan, (ii) the absence of certain governmental orders prohibiting the Merger, (iii) the accuracy of the representations and warranties of each party contained in the Merger Agreement (subject to certain materiality qualifications) and (iv) each party’s compliance with or performance of the covenants and agreements in the Merger Agreement in all material respects.

The Company has made customary representations, warranties and covenants in the Merger Agreement, including, among others, covenants (i) to conduct its business in all material respects in the ordinary course consistent with past practices during the period between the execution of the Merger Agreement and the closing of the Merger, and (ii) not to engage in specified types of transactions or take certain actions during the interim period unless consented to in writing by Parent. The Company is also subject to customary restrictions on its ability to solicit alternative acquisition proposals from third parties and to provide non-public information to, and participate in discussions and engage in negotiations with, third parties regarding alternative acquisition proposals, with customary exceptions for alternative acquisition proposals that the Board determines either constitute or could reasonably be expected to lead to a Superior Proposal (as defined in the Merger Agreement).

Parent also has agreed to various covenants in the Merger Agreement, including, among others, covenants to take actions that may be necessary in order to obtain approval of the Merger with certain governmental authorities, subject to certain exceptions.

The Merger Agreement contains certain termination rights for the Company and Parent. Upon termination of the Merger Agreement under specified circumstances, including in connection with the Company’s entry into a definitive agreement providing for the consummation of a Superior Proposal as permitted under the Merger Agreement, the Company will be required to pay Parent a termination fee of approximately $8.6 million.

The Merger Agreement also provides that, upon termination of the Merger Agreement under specified circumstances, Parent will be required to pay the Company a termination fee of approximately $17.2 million (the “Parent Termination Fee”). The Parent Termination Fee will become payable from Parent to the Company if, subject to certain requirements and exceptions, the Merger Agreement is terminated by the Company in the event that (i) Parent and/or Merger Sub have breached or failed to perform any of its respective representations, warranties, covenants or other agreements set forth in the Merger Agreement such that the applicable closing conditions would not be satisfied or (ii) all of Parent’s conditions to closing are satisfied or waived and Parent has failed to consummate the Merger.

During the three months ended March 27, 2016, we incurred $1.1 million in costs associated with the Merger Agreement, which was recorded as restructuring and other charges in our condensed consolidated statement of operations.

Voting Agreement

Concurrent with the execution of the Merger Agreement, the directors and certain executive officers of Mattson, in their capacities as holders of Company Common Stock or other equity interests of the Company, entered into a Voting Agreement with Parent (the “Voting Agreement”) pursuant to which each agreed, among other things, to (i) vote their Company Common Stock for the approval of the Merger Agreement and against any alternative proposal, and (ii) comply with certain restrictions on the disposition of their Company Common Stock, subject to the terms and conditions contained in the Voting Agreement. Each stockholder party to the Voting Agreement has granted an irrevocable proxy in favor of Parent to vote his or her shares or other equity interests as required by the terms of the Voting Agreement. The Voting Agreement will terminate upon the earlier of (a) the Effective Time, (b) the termination of the Voting Agreement by Parent, (c) the termination of the Merger Agreement in accordance with its terms or (d) a material modification, waiver or amendment of the Merger Agreement that (x) reduces the amount or changes the form of consideration to be paid to such stockholder or (y) creates any additional conditions to the consummation of the Merger (unless such stockholder consents to such modification, waiver or amendment).