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Background Statement for SEMI Draft Document 4771C
New Standard: TEST METHOD FOR EQUIPMENT FAN FILTER UNIT (EFFU) PARTICLE REMOVAL
Notice: This background statement is not part of the balloted item. It is provided solely to assist the recipient in reaching an informed decision based on the rationale of the activity that preceded the creation of this Document.
Notice: Recipients of this Document are invited to submit, with their comments, notification of any relevant patented technology or copyrighted items of which they are aware and to provide supporting documentation. In this context, “patented technology” is defined as technology for which a patent has issued or has been applied for. In the latter case, only publicly available information on the contents of the patent application is to be provided.
Background
If a semiconductor production line does not operate in ultra-clean levels, foreign particles introduced during the process may prevent production of semiconductor device to exact specifications. Therefore, Clean Technology is critical to the production line. To achieve particle free clean environment in process equipment many semiconductor and flat panel display (FPD) manufacturers are adopting equipment fan filter unit (EFFU). However, the particle removal characteristic of EFFU is not well defined because of any characteristic removal characteristic test standard.
Therefore, it is necessary to develop a test method that will be generally reliable and acceptable in order to standardize EFFUs and spread out standard guidelines of EFFUs.
Revision Control
Date / Version / Name / Edits03-Jan-2012 / 1.0 / SangKyooJeon / First version of this ballot placed into the template.
06-Apr-2012 / 2.0 / SangKyooJeon / Update §5 Terminology mainly.
08-Aug-2012 / 3.0 / SangKyooJeon / Update §5 Terminology mainly.
This revision control records activity within the task force as well as formal submit and resubmit dates and results per SEMI. Entries have been made by the task force.
Review and Adjudication Information
Task Force Adjudication / Committee AdjudicationGroup: / KoreaEquipment Cleanness TF / Korea Facilities Technical Committee
Date:
Time & Time Zone:
Location: / SEMI Korea office / SEMI Korea office
City, State/Country: / Seoul, Korea / Seoul, Korea
Leader(s): / SangKyooJeon (KILT),
/ Kwangsun Kim (KoreaUniversity of Technology)
Document Originator(s) / SangKyooJeon (KILT),
/ Insoo Cho (Shinsung ENG)
Standards Staff: / Natalie Shim (SEMI Korea)
82.2.531.7808
/ Natalie Shim (SEMI Korea)
82.2.531.7808
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline. Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
Page 1Doc. 4771C SEMI
Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA95134-2127
Phone: 408.943.6900, Fax: 408.943.7943
hb khghgh1000A4771C
This meeting’s details are subject to change, and additional review sessions may be scheduled if necessary. Contact the task force leaders or Standards staff for confirmation.
Telephone and web information will be distributed to interested parties as the meeting date approaches. If you will not be able to attend these meetings in person but would like to participate by telephone/web, please contact Standards staff.
SEMI Draft Document 4771C
NEW STANDARD: TEST METHOD FOR EQUIPMENT FAN FILTER UNIT (EFFU) PARTICLE REMOVAL
1 Purpose
1.1 This test method covers a procedure for measuring particle removal characteristic of equipment fan filter unit(EFFU) installed inside equipment.
1.2 Since EFFU is an assembly of particle filter, fan, and motor, the integrity of these parts is very important for the performance of EFFU. So a conventional particle removal test method for particle filters is not suitable to evaluate EFFU particle removal performance.
2 Scope
2.1 This test method defines an evaluation method for EFFU which is installed inside an enclosed space to remove particles that are generated inside process equipment. The particle removal performance of EFFUs is usually depending on the performance of filter media and air flow rate. To understand a performance of an EFFU, the filter media characteristic, air flow rate and the integrity of EFFU parts should be considered simultaneously. This test method is intended to demonstrate the system performance of EFFU.
NOTICE:SEMI Standards and Safety Guidelines do not purport to address all safety issues associated with their use. It is the responsibility of the users of the Documents to establish appropriate safety and health practices, and determine the applicability of regulatory or other limitations prior to use.
3 Limitations
3.1 If the particle size distribution of interest is far different from that of test particles, the EFFU particle removal characteristic will be different.
3.2 Particles in the range of around 0.1 to 0.3µm in diameter are relatively hard to remove by particle filters compare to other size particles.
3.3 This test method does not apply to Fan Filter Unit (FFU).
3.4 The particle concentration inside the test chamber should not exceed the upper concentration limit of the particle counters as specified by the manufacturer.
3.5 The test result of EFFU may not be suitable for applying it in open environment.
4 Related Documents
4.1 ISO Standards[1]
4.1.1 ISO14644-3 — Clean rooms and associated controlled environments – Part 3: Metrology and test methods.
4.1.2 ISO14644-4 — Clean rooms and associated controlled environments – Part 4: Design, Construction and Start-up
4.1.3 ISO 554—Standard atmospheres for conditioning and/or testing - Specifications
4.2 SEMI Standard
4.2.1 SEMI F38-0699 — Test method for efficiency qualification of point-of-use gas filters
NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.
5 Terminology
5.1 Abbreviations and Acronyms
5.1.1 CPC— condensation particle counter
5.1.2 EFFU — equipment fan filter unit
5.1.3 FPD— flat panel display
5.1.4 OPC— optical particle counter
5.1.5 FFU— fan filter unit
5.2 Definitions
5.2.1 equipment fan filter unit— an active particle removal device with an assembly of filter, fan, motor and exterior case that is installed inside an equipment.
6 Test Set-up
6.1 Test equipment
6.1.1 Test chamber —Theinside of test chamber must be fabricated with clean stainless steel. The make-up air must be filtered by ULPA filter.The chamber volume should be large enough to continue the test for more than 100 seconds until to reach the particle concentration of 0.1% of the initial particle concentration.
6.1.2 Operating temperature and relative humidity(RH) — Tests shall be executed at 23±2oC and 50±5 % RH according to ISO 554.
6.1.3 Particle counter — a condensation particle counter (CPC) is recommended for particle monitoring equipment. Refer to SEMI F38-0699(Reapproved 1104) section 6.2.
6.1.4 Test specimen — the test EFFU must be placed in the center of the test chamber.
6.1.5 Particle Sampling Probe — an electrically conductive stainless steel sampling tube is recommended to minimize a charged particle sampling loss in the sampling tube.
6.1.6 Test particle — Solid non-volatile particle with the number mean diameter of in the range of 0.1 – 0.3 µm.
7 TestProcedure
7.1 Fill the test chamber with test aerosol.
7.2 The particle monitoring instrument (CPC or OPC) should start monitoring particle concentration in the chamber. The particle sampling probe inlet must be located 10 cm upstream side away from of the center of EFFU inlet face.
7.2.1 It is recommended that the sampling probe inlet should face the incoming air direction.
7.3 Start the EFFU and continuously monitor the particle concentration.
7.4 If the particle concentration inside the test chamber decreases down to less than 0.1% of the initial particle concentration, then stop the test.
8 Calculation of Particle Removal Rate Constant ()
8.1 Theoretical Background — Figure 1 shows a particle concentration change in a test chamber. From this figure the particle concentration change governing equation is as follows;
(1)
where
- V: test chamber volume,
- Ci: particle concentration inside the test chamber
- C0: particle concentration in the make-up air,
- Qe: sampling air flow rate,
- Qi : make-up air flow rate,
- Qr: flow rate of EFFU,
- S : particle generation inside the test chamber,
- R : particle removal by diffusion and by sedimentation to the inside surface of the chamber,
- : particle removal efficiency of EFFU.
- = S – R + QiC0
- = Qe + Qr
Integration of equation (1) becomes
(2)
With boundary condition; Ci= Ci,0at t = 0
(3)
If C0 = 0,S = 0,R = 0then = 0.
Equation (3) becomes
(4)
whereand Ci,0 is the initial particle concentration in the test chamber at time t. represents the particleremoval characteristic of EFFU.
9 Test Result and Reporting
9.1 Figure 2 shows a typical particle removal test set-up for EFFU.
9.2 The particle concentration decay results are shown in Figure 3.
9.3 From the test data the slopes of the regression lines are the particle removal characteristics of the tested EFFUs. Report the average value of after 3 measurements. The regression region must start from at least 10 seconds after the EFFU operation and the regression interval must satisfy section 7.4.
9.4 A sample report format is provided in Related Information 1.
Figure 1
Schematic of a test chamber particle concentration change
Figure 2
Schematic of test chamber
Figure 3
Particle concentration changes as a function of time
10 Summary
10.1 Application of EFFU particle removal characteristic —The particle removal capacity can be calculated from the following equation;
= V (5)
where
- : particle removal capacity, [m3/s]
- V : test chamber volume , [m3]
- : particle removal characteristic, [s-1]
The particle removal characteristic () can be found from the test result and equation 4. More specific application example is in Related Information 1.
NOTICE:Semiconductor Equipment and Materials International (SEMI) makes no warranties or representations as to the suitability of the Standards and Safety Guidelines set forth herein for any particular application. The determination of the suitability of the Standard or Safety Guideline is solely the responsibility of the user. Users are cautioned to refer to manufacturer’s instructions, product labels, product data sheets, and other relevant literature, respecting any materials or equipment mentioned herein. Standards and Safety Guidelines are subject to change without notice.
By publication of this Standard or Safety Guideline, SEMI takes no position respecting the validity of any patent rights or copyrights asserted in connection with any items mentioned in this Standard or Safety Guideline. Users of this Standard or Safety Guideline are expressly advised that determination of any such patent rights or copyrights, and the risk of infringement of such rights are entirely their own responsibility.
RELATED INFORMATION 1SAMPLE REPORT FORMAT FOR PARTICLE REMOVAL CHARACTERISTIC OF EFFU
NOTICE: This Related Information is not an official part of SEMI [designation number] and was derived from the work of the global [committee name] Technical Committee. This Related Information was approved for publication by full letter ballot procedures on [A&R approval date].
Table R1-1 Particle Removal Characteristic Test Report
Test Conditions / Test particle / Describe the test particle material and size distribution.Chamber Volume (W x D x H) / Describe the test chamber volume and dimensions.
Test chamber temperature & Humidity / Describe the test chamber temperature and humidity during the EFFU test.
EFFU Test Operating Mode / Describe the EFFU operating mode during the test if applicable.
Particle counter type / Particle counter that is used during the test. e.g) OPC or CPC
Manufacture of the counter / Describe the manufacture of the particle counter.
Counter model / Describe the particle counter model
Sample flow (Qe) / Describe the particle counter sampling flow rate.
Test Results / Sample of the test result with regression line /
Particleremoval characteristic () / Write the particle removal characteristic value, i.e., the absolute value of the regression line slope.
Correlation coefficient / Write the correlation coefficient of the regression line.
η·Qr / Write η·Qr value.
R1-1.2 For example, to estimate a cleaning time to reach 99.9% particle removal in 10 m3 enclosed space using EFFU_1, the calculation procedure is as follows if EFFU_1 is tested in V = 4.91 m3 chamber and = 0.0465, Qe= 1 lpm;
(6)
Since
0.228 = 0.001 m3/60 s +,
= 0.228.
This result implies that if the sampling flow rate Qe is small, then . To apply EEFU_1 in 10m3 chamber,.
From equation (4),
(7)
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline. Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
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