Background Statement for SEMI Draft Document 4771B New Standard: TEST METHOD FOR EQUIPMENT FAN FILTER UNIT (EFFU) PARTICLE REMOVAL

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1 Background Statement for SEMI Draft Document 4771B New Standard: TEST METHOD FOR EQUIPMENT FAN FILTER UNIT (EFFU) PARTICLE REMOVAL Notce: Ths background statement s not part of the balloted tem. It s provded solely to assst the recpent n reachng an nformed decson based on the ratonale of the actvty that preceded the creaton of ths Document. Notce: Recpents of ths Document are nvted to submt, wth ther comments, notfcaton of any relevant patented technology or copyrghted tems of whch they are aware and to provde supportng documentaton. In ths context, patented technology s defned as technology for whch a patent has ssued or has been appled for. In the latter case, only publcly avalable nformaton on the contents of the patent applcaton s to be provded. Background If a semconductor producton lne does not operate n ultra-clean levels, foregn partcles ntroduced durng the process may prevent producton of semconductor devce to exact specfcatons. Therefore, Clean Technology s crtcal to the producton lne. To acheve partcle free clean envronment n process equpment many semconductor and flat panel dsplay (FPD) manufacturers are adoptng equpment fan flter unt (EFFU). However, the partcle removal characterstc of EFFU s not well defned because of any characterstc removal characterstc test standard. Therefore, there s a need to develop a test method that wll be generally relable and acceptable n order to standardze EFFUs and spread out standard gudelnes of EFFUs. Ths s the thrd verson of the 4771 Document and 4771A were ssued n cycle 2 and cycle 7 of 2011 respectvely. Both ballots were faled commttee revew and sent to TF for rework. Revew and Adjudcaton Informaton Task Force Adjudcaton Commttee Adjudcaton Group: Equpment Cleanness Task Force Korea Facltes Techncal Commttee Date: Wednesday, June 20, 2012 Wednesday, June 20, 2012 Tme & Tme Zone: 13:00 15:00 15:00 17:00 (KST) Locaton: SEMI Korea offce SEMI Korea offce Cty, State/Country: Seoul, Korea Seoul, Korea Kwang Sun Km (KoreaUnversty of Technology) kskm@kut.ac.kr Leader(s): Insoo Cho (Shnsung ENG) Kwang Sun Km (KoreaUnversty of nsoocho@shnsung.co.kr Technology) Kang-Ho Ahn (HYU) Insoo Cho (Shnsung ENG) khahn@hanyang.ac.kr YouSeop Km (DKU) wangcho@dankook.ac.kr Document Orgnator(s): Kang-ho Ahn (Hanyang Unversty) Kang-ho Ahn (Hanyang Unversty) Standards Staff: khahn@hanyang.ac.kr Natale Shm (SEMI Korea) eshm@sem.org khahn@hanyang.ac.kr Natale Shm (SEMI Korea) eshm@sem.org Ths meetng s detals are subject to change, and addtonal revew sessons may be scheduled f necessary. Contact the task force leaders or Standards staff for confrmaton. Telephone and web nformaton wll be dstrbuted to nterested partes as the meetng date approaches. If you wll not be able to attend these meetngs n person but would lke to partcpate by telephone/web, please contact Standards staff.

2 Semconductor Equpment and Materals Internatonal SEMI Draft Document 4771B NEW STANDARD: TEST METHOD FOR EQUIPMENT FAN FILTER UNIT (EFFU) PARTICLE REMOVAL 1 Purpose 1.1 Ths test method covers a procedure for measurng partcle removal characterstc of equpment fan flter unt (EFFU) nstalled nsde an enclosed space. 1.2 Snce EFFU s a combnaton of ar flter and the assembly of fan, motor and frame, the ntegrty of these parts s very mportant for the performance of EFFU. So a conventonal partcle removal test method for ar flters s not sutable for EFFU partcle removal performance. 2 Scope 2.1 Ths test method defnes an evaluaton method for EFFU whch s nstalled nsde an enclosed space to remove partcles that are generated nsde process equpment. The partcle removal performance of EFFUs s usually dependng on the performance of flter meda and ar flow rate. To understand a performance of an EFFU, the flter meda characterstc, ar flow rate and the ntegrty of EFFU parts should be consdered smultaneously. Ths test method s ntended to demonstrate the system performance of an EFFU. NOTICE: SEMI Standards and Safety Gudelnes do not purport to address all safety ssues assocated wth ther use. It s the responsblty of the users of the Documents to establsh approprate safety and health practces, and determne the applcablty of regulatory or other lmtatons pror to use. 3 Lmtatons 3.1 If the partcle sze dstrbuton of nterest s far dfferent from that of test partcles, the EFFU partcle removal characterstc wll be dfferent. 3.2 Partcles n the range of around 0.1 to 0.3µm n dameter are not easly removed by ar flter compare to other partcles of nterest. 3.3 Ths test method does not apply to Fan Flter Unt (FFU). 3.4 The upper concentraton lmt of the CPC/OPC as specfed by the manufacturer should not be exceeded. 3.5 The test result wll be useful n selectng an approprate EFFU for semconductor process equpment desgn. Ths test result of EFFU may not be sutable for applyng n open envronment. 4 Related Documents 4.1 ISO Standards ISO Clean rooms and assocated controlled envronments Part 3: Metrology and test methods ISO Clean rooms and assocated controlled envronments Part 4: Desgn, Constructon and Startup 4.2 SEMI Standard SEMI F Test method for effcency qualfcaton of pont-of-use gas flters NOTICE: Unless otherwse ndcated, all documents cted shall be the latest publshed versons. 1 Internatonal Organzaton for Standardzaton ISO Central Secretarat, 1, rue de Varembé, Case postale 56, CH-1211 Geneva 20, Swtzerland. Telephone: ; Fax: Webste: Ths s a Draft Document of the SEMI Internatonal Standards program. No materal on ths page s to be construed as an offcal or adopted Standard or Safety Gudelne. Permsson s granted to reproduce and/or dstrbute ths document, n whole or n part, only wthn the scope of SEMI Internatonal Standards commttee (document development) actvty. All other reproducton and/or dstrbuton wthout the pror wrtten consent of SEMI s prohbted. Page 1 Doc. 4771B SEMI

3 Semconductor Equpment and Materals Internatonal 5 Termnology 5.1 Abbrevatons and Acronyms CPC condensaton partcle counter EFFU equpment fan flter unt FPD flat panel dsplay OPC optcal partcle counter FFU fan flter unt 5.2 Defntons equpment fan flter unt an actve partcle removal devce wth flter and the assembly of fan, motor and exteror case that s nstalled n an enclosed space. 6 Test Set-up 6.1 Test equpments Test chamber the test chamber must be fabrcated wth clean electrcally conductve materal and the chamber temperature and humdty must be controlled. The make-up ar must be fltered by HEPA flter Partcle counter A condensaton partcle counter (CPC) s recommended for partcle montorng equpment. Refer to SEMI F (Reapproved 1104) secton Test specmen the test EFFU must be placed at the center of the test chamber Partcle Samplng Probe the probe materal must be electrcally conductve to mnmze a charged partcle samplng loss n the samplng tube Test partcle Sold non-volatle partcle. 7 Test Procedure 7.1 Fll the test chamber wth test aerosol. Ambent aerosol s recommended. 7.2 The partcle montorng nstrument (.e., CPC) should start montorng partcle concentraton n the chamber. The partcle samplng probe nlet must be located 10 cm upstream sde away from of the center of EFFU nlet face It s recommended that the samplng probe nlet should face the ncomng ar drecton to mnmze the partcle samplng loss. 7.3 Start the EFFU and contnuously montor the partcle concentraton. 7.4 If the partcle concentraton nsde the test chamber decreases low enough to get regresson lne, then stop samplng It s recommended to take sample untl the concentraton decreases down to less than 1% of the ntal partcle concentraton. 8 Calculaton of Partcle Removal Rate Constant (γ ) 8.1 Theoretcal Background Fgure 1 shows a partcle concentraton change n a test chamber. From ths fgure the partcle concentraton change governng equaton s as follows; dc V = S R Qe C η Qr C dt = ( S R+ Q C ) ( Q + η Q ) = β α C 0 e r C (1) Ths s a Draft Document of the SEMI Internatonal Standards program. No materal on ths page s to be construed as an offcal or adopted Standard or Safety Gudelne. Permsson s granted to reproduce and/or dstrbute ths document, n whole or n part, only wthn the scope of SEMI Internatonal Standards commttee (document development) actvty. All other reproducton and/or dstrbuton wthout the pror wrtten consent of SEMI s prohbted. Page 2 Doc. 4771B SEMI

4 Semconductor Equpment and Materals Internatonal where V: test chamber volume, C : partcle concentraton nsde the test chamber C 0 : partcle concentraton n the make-up ar, Q e : samplng ar flow rate, Q : make-up ar flow rate, Q r : flow rate of EFFU, S : partcle generaton nsde the test chamber, R : partcle removal by dffuson and by sedmentaton to the nsde surface of the chamber, η: partcle removal effcency of EFFU. β = S R + Q C 0 α = Q e + η Q r Integraton of equaton (1) becomes dc β α C = dt V (2) Wth boundary condton; C = C,0 at t = 0 If C 0 = 0, S = 0, R = 0 then β = 0. Equaton (3) becomes C β β C,0 α = α α C = C = C,0,0 α t exp V exp α t exp V ( γ t) (3) (4) α where γ = and C,0 s the ntal partcle concentraton n the test chamber at tme t. γ represents the partcle V removal characterstc of EFFU. 9 Test Result and Reportng 9.1 Fgure 2 shows a typcal partcle removal test set-up for EFFU. 9.2 A commercal CPC samples 1 lpm of ar from the test chamber and the make-up ar s flter by HEPA flter and ntroduced through the upper corner of the test chamber. 9.3 The whole system s placed n a room temperature condton. 9.4 The partcle concentraton decay results are shown n Fgure From the test data the slopes of the regresson lnes are the partcle removal characterstcs of the tested EFFUs. Report the average value of γ after 3 measurements. 9.6 A sample report format s provded n Related Informaton 1 Ths s a Draft Document of the SEMI Internatonal Standards program. No materal on ths page s to be construed as an offcal or adopted Standard or Safety Gudelne. Permsson s granted to reproduce and/or dstrbute ths document, n whole or n part, only wthn the scope of SEMI Internatonal Standards commttee (document development) actvty. All other reproducton and/or dstrbuton wthout the pror wrtten consent of SEMI s prohbted. Page 3 Doc. 4771B SEMI

5 Semconductor Equpment and Materals Internatonal Q C o C,o η EFFU Q r V, C Fgure 1 Schematc of a test chamber partcle concentraton change R Q e C HEPA Flter CPC EFFU Fgure 2 Schematc of test chamber Ths s a Draft Document of the SEMI Internatonal Standards program. No materal on ths page s to be construed as an offcal or adopted Standard or Safety Gudelne. Permsson s granted to reproduce and/or dstrbute ths document, n whole or n part, only wthn the scope of SEMI Internatonal Standards commttee (document development) actvty. All other reproducton and/or dstrbuton wthout the pror wrtten consent of SEMI s prohbted. Page 4 Doc. 4771B SEMI

6 Semconductor Equpment and Materals Internatonal 10 Summary Number of Partcles, #/cm 3 1e+7 1e+6 1e+5 1e+4 1e+3 1e+2 1e+1 1e+0 1e Tme, sec EFFU_Model 1 EFFU_Model 2 Natural decay Fgure 3 Partcle concentraton changes as a functon of tme 10.1 Applcaton of EFFU partcle removal characterstc The partcle removal capacty can be calculated from the followng equaton; where α : partcle removal capacty, [m 3 /s] V : test chamber volume, [m 3 ] γ : partcle removal characterstc, [s -1 ] α = V γ (5) The partcle removal characterstc (γ ) can be found from the test result and equaton 4. More specfc applcaton example s n Related Informaton 1. NOTICE: Semconductor Equpment and Materals Internatonal (SEMI) makes no warrantes or representatons as to the sutablty of the Standards and Safety Gudelnes set forth heren for any partcular applcaton. The determnaton of the sutablty of the Standard or Safety Gudelne s solely the responsblty of the user. Users are cautoned to refer to manufacturer s nstructons, product labels, product data sheets, and other relevant lterature, respectng any materals or equpment mentoned heren. Standards and Safety Gudelnes are subject to change wthout notce. By publcaton of ths Standard or Safety Gudelne, SEMI takes no poston respectng the valdty of any patent rghts or copyrghts asserted n connecton wth any tems mentoned n ths Standard or Safety Gudelne. Users of ths Standard or Safety Gudelne are expressly advsed that determnaton of any such patent rghts or copyrghts, and the rsk of nfrngement of such rghts are entrely ther own responsblty. Ths s a Draft Document of the SEMI Internatonal Standards program. No materal on ths page s to be construed as an offcal or adopted Standard or Safety Gudelne. Permsson s granted to reproduce and/or dstrbute ths document, n whole or n part, only wthn the scope of SEMI Internatonal Standards commttee (document development) actvty. All other reproducton and/or dstrbuton wthout the pror wrtten consent of SEMI s prohbted. Page 5 Doc. 4771B SEMI

7 Semconductor Equpment and Materals Internatonal RELATED INFORMATION 1 SAMPLE REPORT FORMAT FOR PARTICLE REMOVAL CHARACTERISTIC OF EFFU NOTICE: Ths Related Informaton s not an offcal part of SEMI [desgnaton number] and was derved from the work of the global [commttee name] Techncal Commttee. Ths Related Informaton was approved for publcaton by full letter ballot procedures on [A&R approval date]. Table R1-1 Partcle Removal Characterstc Test Report Test Condtons Test partcle Chamber Volume (W x D x H) Test chamber temperature & Humdty EFFU Test Operatng Mode Partcle counter type Manufacture of the counter Counter model Descrbe the test partcle materal and sze dstrbuton. Descrbe the test chamber volume and dmensons. Descrbe the test chamber temperature and humdty durng the EFFU test. Descrbe the EFFU operatng mode durng the test f applcable. Partcle counter that s used durng the test. Ex) OPC or CPC Descrbe the manufacture of the partcle counter. Descrbe the partcle counter model Sample flow Descrbe the partcle counter samplng flow rate. 1e+6 1e+5 EFFU_Type 1 Plot 1 Regr Test Results Sample of the test result wth regresson lne Number of Partcles, #/cm 3 1e+4 1e+3 1e+2 1e+1 1e+0 Partcle removal characterstc (γ ) Correlaton coeffcent η Q r 1e Tme, sec Wrte the partcle removal characterstc value. Wrte the correlaton coeffcent of regresson lne. Wrte η Q r value. Ths s a Draft Document of the SEMI Internatonal Standards program. No materal on ths page s to be construed as an offcal or adopted Standard or Safety Gudelne. Permsson s granted to reproduce and/or dstrbute ths document, n whole or n part, only wthn the scope of SEMI Internatonal Standards commttee (document development) actvty. All other reproducton and/or dstrbuton wthout the pror wrtten consent of SEMI s prohbted. Page 6 Doc. 4771B SEMI

8 Semconductor Equpment and Materals Internatonal For example, to estmate a cleanng tme to reach 99.9% partcle removal n 10 m 3 enclosed space usng EFFU_1, the calculaton procedure s as follows; Snce α = Q + η Q e r ( ) ( 4.91) = = m 3 /60 s + η Q, r η Q r = Ths result mples that f the samplng flow rate Q e s small, then α η Qr To apply EFFU_1 n 10 m 3 chamber, α γ = = = V 10 From equaton (4), C C = exp γ t α = γ V = (6) /, = exp t = 303 s. ( ) ( t) (7) Ths s a Draft Document of the SEMI Internatonal Standards program. No materal on ths page s to be construed as an offcal or adopted Standard or Safety Gudelne. Permsson s granted to reproduce and/or dstrbute ths document, n whole or n part, only wthn the scope of SEMI Internatonal Standards commttee (document development) actvty. All other reproducton and/or dstrbuton wthout the pror wrtten consent of SEMI s prohbted. Page 7 Doc. 4771B SEMI