Activity Number: 4922
SNARF for: New Standard: Guide for Equipment Fan Filter Unit (EFFU) Performance
SEMI International Standards
SEMI New Activity Report Form (SNARF)
1. Rationale: When the level of cleanliness in semiconductor equipment is not satisfied, it causes interfaces between thin films on raw wafer to be contaminated and leads to not only declination of electronics but also shortening the life time of chips. Therefore, it is extremely essential to keep production line of semiconductor constantly.
|Originating Global Technical Committee: Facilities|
|Originating Technical Committee Region: Korea|
|Task Force in which work is to be carried out: Equipment Cleanness Task Force |
Manufacturers of semiconductor equipment should present performance specifications of EFFUs (Equipment Fan Filter Units) to EFFUs suppliers in order to achieve highest yield rate during mass semiconductor production However, semiconductor equipment makers unfortunately do not present EFFUs performance specifications to EFFUs suppliers. Therefore, it induces a variety of types in EFFUs to spread out depending on various types of semiconductor equipment. It causes diversification of EFFUs in performance specification as well as sizes.
In accordance with many different kinds of EFFUs in performance, the guide in performance levels for EFFUs which leads to most efficient productivity in semiconductor manufacture line is desperately needed to reduce energy waste.
Rate the Estimated Effect on the Industry
2: Major effect on an industry sector - identify the relevant sector
Rate the Estimated Technical Difficulty of the Activity
II: Some Difficulty - Disagreements on known requirements exist but developing consensus is possible
a: Define the areas to be covered or addressed by this activity or document:
This standard provides common guide for EFFUs which work out during operation and is mainly focusing on power consumption and airflow circulation. It recommends the EFFUs standard performance to all EFFUs manufacturers and vendors in order that EFFUs can be upgraded to most compatible and competitive parts as well as lowest energy consumption. It also can be referenced by and integrated into a relevant industry recommended for field practice or suggestions of standard.
The recommendation for the EFFUs standard performance includes following items:
-Average velocity specified with tolerance ±5%
-CMM (cubic meter per minute) specified with tolerance ±5%
-airflow uniformity with standard deviation divided by average airflow velocity equal to or less than 0.25
-equal to or less than 6.5 W/CMM (watt/CMM)
-equal to or less than 65 dBA of sound noise level
-degree of vibration equal to or less than 1mm
The test procedure instruction for the characterization of EFFUs includes following items:
1. Test method for measuring average velocity with unit of meter per second.
- The number of measuring point of average velocity are determined by the computational result of equation as the number of measuring point = filter area(m X m) of air going through divided by 4 times 100.
- Each location of measuring point is determined by dividing filter area of EEFU by the number of measuring point and allocating a measuring point to center of each sub-area.
- Average velocity is measured utilizing 3-dimensional wind velocimeter at each point allocated by 5cm distanced vertically away with laminar flow remained from the filter face.
2. Test method of CMM which means cubic meter per minute as airflow rate coupled with total pressure of EFFU.
- Pressure differential is measured between front and rear of the nozzle which airflow goes through inside air chamber.
-CMM is calculated using Bernoulli equation and flow continuity equation.
3. Test method of airflow uniformity measured at several locations vertically far away with laminar flow remained from air-filter.
- maintain in order that standard deviation of wind velocity at several locations may be equal or less than 0.05 based on the test method described in section 1. above.
4. W/CMM where W means wattage as power consumption while CMM is described as above.
- divid power consumption of EFFU by airflow rate obtained satisfactorily from test method described in section 2 and 3 above.
5. Test method of sound noise level
- repeatedly measure sound noise level by three times at distance away 1m vertically from filter under the condition of anechoic sound noise level equal to or less than 30dB.
- respective value of sound noise level is repeatedly measured three times in the range of 4 Hz to 3.2KHz for 20 seconds.
- average 3 values of sound noise level
6. Test method of vibration
- structure like two cantilevers supporting only two wide edges at bottom face of EFFU is formed while one longitudinal edge at bottom face of EFFU is free of fixation.
- an vibration sensor is attached at the center on one side face among 4 side faces of filter in order to measure displacement of EFFU in operation.
- repeatedly measure vibration by three times with pressure loaded.
- respective value of vibration is repeatedly measured three times utilizing 3-axial sensing of vibration in the range of 0 Hz to 400 Hz for 20 seconds.
- average 3 values of vibration
The objective of this standard is to provide instruction for performance testing and reporting based upon consistent procedures. This can be referenced by and integrated into a relevant industry recommended for field practice or suggestions of standard.
The options is CMM is calculated by multiplying filter area of airflow going through by average velocity.
The other option is CMM is calculated using Bernoulli equation and flow continuity equation after pressure differential is measured between front and rear of the nozzle which airflow goes through inside air chamber.
However, it is recommend to measure CMM derived from experimental measurement of pressure differential inside air chamber because value of CMM computed from only multiplying average velocity by filter area is less accurate than that of CMM calculated using conservation of mass and energy containing pressure differential measured.
b: Expected result of activity
3. Projected Timetable for Completion:
|a: General Milestones|
|a. Activity Start: 03/01/2010||b. 1st Draft by: 10/17/2011|
|c. Preballot by: ||d. Technical Ballot by: 10/17/2011|
|e. Committee Approval By:06/30/2012|
The resulting document is expected NOT to be a Safety Guideline
Intellectual Property Considerations:
a. In complying with the standard or safety guideline to be developed, the use of patented technology or a copyrighted item(s) is NOT required
b. The body of the standard and any appendices or related information sections will NOT include copyrighted material
Comments, Special Circumstances: Background:
1. The SNARF was approved by NA Facilities on July 22, 2009 and it is transferred to Korea Facilities and approved on October 21, 2010
2. The transferred SNARF is also revised its scope and Document type from "Specification" to "Guide" on September 21, 2011.
Approval: Activity approved by Committee/GCS on March 30, 2010
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