Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone: 408.943.6900, Fax: 408.943.7943
hb khghgh1000A5428
Background Statement for SEMI Draft Document 5564C
New Standard: Test Methodforthe Measurementof Chlorinein Siliconby Ion Chromatography
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 Statement
More and more granular silicon isbeing produced and used in the photovoltaic industry. Thusthe quality of polysilicon is very important for the user.As researched, more chlorine remains in granular silicon than in chunk silicon. Chlorine remaining in the silicon mayaffect the quality. Therefore, it is necessary to develop a standardized method to measure the chlorine in silicon.
Review and Adjudication Information
Task Force Review / Committee AdjudicationGroup: / Polysilicon TF / China PV Committee
Date: / TBD / Nov. 20th, 2015
Time &Timezone: / TBD / 9:00- 18:00
Location: / TBD / Shenzhen Hotel
City, State/Country: / China / Shenzhen, Guangzhou, China
Leader(s): / Xiaoxia Liu( GCL)
Li He (CPVT) / Guangchun Zhang(CanadianSolar)
Jun Liu(CESI)
Standards Staff: / Kris Shen(SEMI China)
/ Kris Shen(SEMI China)
Meeting date and time are subject to change, and additional TF review sessions may be scheduled if necessary. Contact the task force leaders or Standards staff for confirmation.Check for the latest schedule.
If you have any questions, please contact the Poly-Silicon TF Leader.
Xiaoxia Liu/ GCL
Tel: +86 516 85868888-88500
E-mail:
Or contact SEMI Staff, Kris
SEMI Draft Document 5564C
New Standard: Test Methodforthe Measurementof Chlorinein Siliconby Ion Chromatography
1 Purpose
1.1 The quality of polysilicon is very important for the user.More and more granular silicon isbeing produced and used to produce polysilicon for use in the photovoltaicindustry. Research shows that more chlorine remains in granular silicon than inchunk silicon. Chlorine remaining in the silicon affects the quality. Thus, it is necessary to develop a method to measure the chlorine in silicon.
1.2 This test method can facilitate unification of protocols and test results among worldwide laboratories used for monitoring or qualifying chlorine in silicon.
2 Scope
2.1 This Standard providesa test method for measuring the chlorine in silicon by Ion Chromatography.
2.2 This test method can be used for various rod, chunk, granule and chip sizes for polysilicon to determine the chlorine content. Forms of silicon other than granular needto be pulverized, in particle size rangeof 200~3000 µm. The detection limit for routine analysis is 1.0 ppmw.
2.3 Relative unitsppbw and ppmw are used for impurity concentration values in this test method. For conversion to other units, see SEMI AUX022.
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 None
NOTE 1:Taketheutmostcaretoensureall contact to the sample containers are pure;rinse containerswithcopious amounts ofDIwater anduse nitrogen to blow clean.
4 Referenced Standards and Documents
4.1 SEMI Standards and Documents
SEMI C35 –– Specifications and Guideline for Nitric Acid
SEMI AUX022 — Conversion of Units for Impurity Concentrations in Silicon
4.2 ASTM Standards[1]
ASTM D1193 — Standard Specification for Reagent Water
ASTM E122 — Standard Practice for Calculating Sample Size to Estimate, with Specified Precision, the Average for a Characteristic of a Lot or Process
4.3 Federal Standard[2]
ISO/DIS 14644-1— Cleanrooms and associated controlled environments—Part 1: Classification of air cleanliness by particle concentration
NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.
5 Terminology
5.1 Refer to SEMI Standards Compilation of Terms (COTs) for a list of the most current terms and their definitions.
5.2 Abbreviations and Acronyms
5.2.1 IC— ion chromatography
5.2.2 ppmw—part per million weight
5.2.3 ppbw—part per billion weight
5.3 Definitions
5.3.1 Granularsilicon—nearlysphericalgranules (200~3000µm)ofsiliconasproduced in afluidizedbedreactor.
5.3.2 Method blank— a solution of acid prepared using the preparation method without a specimen or test sample used to establish the contribution of trace chlorine contamination from the laboratory environment, reagents or labware to the background.
5.3.3 Certified Reference Material (CRM) – a NIST traceable single or multi-element solution standard.
5.3.4 Standard samples — samples prepared to known concentrations of the analytes, typically 0.1ppma, 0.2 ppma, 0.5 ppma and 1 ppma to provide a chlorine standard for the IC instrument.
6 Summary of Test Method
6.1 Release—Whenheated to 1500℃ the silicon sample melts (melting point of silicon is 1414℃) and releases chlorine in the form of SiCl4vapor at the melting point.
6.2 Absorption—Using argon as a purge gas through the tube, the chlorine in the form of SiCl4 is carriedthrough twobubblersin seriesfilled withultrapure water.
6.3 Measurement—Afterabsorbing and decomposing the SiCl4 in the scrubbers, thetwo aqueous solutionsare analyzed byion chromatography.
7 Apparatus
7.1 IC — ion chromatographyinstruments
7.2 Electronic balance(s)—0.1 mg accuracy for weighing silicon samples
7.3 High temperature tube furnace—forheating the silicon sample to at least 1500℃
7.4 Sample container—quartz boat for holding the silicon sample that is able to hold at least 2g of sample
7.5 Sample tube—made of Al2O3, used for melting the silicon samples
7.6 Bubblers—10 ml capacity used forscrubbingof theexhaust gas
7.7 Ultrasound equipment —eluentssonicated for an IC instrument
8 Reagents and Materials
8.1 Ultrapure water—Unless otherwise indicated, reagent water should be conformant to ASTM specification D1193.
8.2 Argon gas —99.999% (V/V) minimum
8.3 Standard solution—1000ppmw(mg/kg) CL solution, CRM
9 Safety Precautions
9.1 Users of the tube high temperature furnace must be trained, in accordance with the operating rules, to avoid injury.
10 Sampling
10.1 This test method is intended for sampling of silicon lots. Typically, one 5kg bag from a lot is selected for sampling. The sample is taken from this bag, and the chlorine values analyzed are assumed representative of the lot. Statistical techniques, such as process capability ratios, are used to determine actual sampling plans for manufacturing processes. A choice of sampling plans is found in ASTM Practice E122. For referee purposes, a sampling plan shall be agreed upon before conducting the test. Contamination during the sampling procedure is a critical concern and shallbe avoided.
11 Preparation of Apparatus
11.1 Requirements according to the sample configuration corresponding concentration of sulfuric acid solution, eluent—use 0.45 m filter membrane filtration,then ultrasound itfor 10 minutes.
11.2 Operating exhaust—loosen the needle valve.Manually set the workstation withapump flow rate of 2.0ml/min.Suction the airfrom the needle valvewith a syringeuntil the eluent continuously outflows from the needle valve with no bubbles.Before tightening the valve, pump flow rate shall be set at 0.7ml/min, and care should be taken to avoiddamage tothe separation column.
11.3 The samplesshould not beanalyzed before the baseline of the instrument is stable.
12 Calibration and Standardization
12.1 Method blank — a solution of acid prepared using the preparation method without a specimen or test sample used to establish the contribution of trace chlorine contamination from the laboratory environment, reagents or labware to the background.
12.2 Calibration Graph — use the standard solution in ¶8.3, configured into a standard solution of 0.1ppmw, 0.2ppmw, 0.5ppmwand 1ppmw, using an ion chromatograph to analyze, and produce a calibration graph based on workstation applicationsfor the quantitative analysis of the silicon sample.
13 Procedure
13.1 Weighapproximately 5.0g of granular polysilicon into the samplecontainer, and putthe container into the center of the high temperature tube furnace.
13.2 Prepare two bubble absorption bottles,both equippedwith 10 ml ofultrapure water, in series, and connect to the furnace exhaust.
13.3 Adjust the flow rate of the argon gasto 500 ml/min through the furnace and into the bubblers.
13.4 Program the tube high temperature furnace temperature to heat fromroom temperature to 1500℃.Hold for 20 minutes at 1500℃,and then cool down to room temperature.
13.5 Remove the absorption bottles andanalyze the contentsfor chloride ionsby IC.
13.6 Repeatthe same steps, but with no sample for testingthemethod blank.
NOTE 2:The weight of the sample could be modified according to the concentration of the CL in silicon; the more sample taken, the lower the detection limit.
14 Calculations
14.1 Chlorineconcentration of sample(ppmw, mg/kg):
Computing formula:(1)
Where:
C1:The chloride ion content in the first bubble absorptionbottle, mg/L;
C2: The chloride ion content in the second bubble absorptionbottle, mg/L;
C0: The concentration of blank, mg/L;
V: The volume of water in the bubble absorption bottle,mL;
m:The massof the silicon tested, kg.
15 Report
15.1 The results to be reported— use the arithmetic mean of the parallel samples’ results which should be in a reasonable range of deviation.
Related Document
BS EN ISO 9556:2001—Steel and iron—Determination of the total carbon content— Infrared absorption method after combustion in an induction furnace
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.
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. 5564C SEMI
[1]American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, USA; Telephone: 610.832.9585, Fax: 610.832.9555,
[2]Federal Standard, c/o U.S. Government Printing Office, Washington DC, 20402, USA