SEMI International Standards
Standards New Activity Report Form (SNARF)
Date Prepared: 10/15/2008Revised (if Applicable):

Document Number: 4675
SNARF for: New Standard: Test Method for the Measurement of Elemental Impurity Concentrations in Silicon Feedstock by Bulk Digestion, Inductively-Coupled-Plasma Mass Spectrometry

Originating Global Technical Committee: Photovoltaic (PV) - Materials
Originating TC Chapter: North America
Task Force (TF) in which work is to be carried out: International PV Analytical Test Methods Task Force
Note: If a new task force is needed, also submit a task force organization form (TFOF)

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1. Rationale:
a. Describe the need or problem addressed by this activity.
(Indicate the customer, what benefits they will receive, and if possible, quantify the impact on the return on investment [ROI] if the Document is implemented.)
The manufacturers of crystalline and micro-crystalline silicon to be used in silicon solar cells, purchase or manufacture for internal use, silicon that is used as feedstock. This Si Feedstock can take many physical forms, including, for example, granules, powders, polysilicon chunks, wafers, reclaimed silicon, and top and tail cuts from silicon boules.

The purity level of PV Si Feedstock can affect solar cell efficiency, as well as the productivity of some processes used to transform the PV Si Feedstock into solar cells.

SEMI has many test methods that can be used to determine the purity level of PV Si Feedstock, depending upon its physical form and the elements of interest: SEMI MF 397-02 for measuring net resistivity, SEMI 1389-00 for measuring dopants by photoluminescence, SEMI MF 1724-01 for measuring surface metal contamination on granules, chunks or powders by acid extraction followed by atomic absorption spectroscopy, SEMI1188-1105 for measuring interstitial oxygen by Fourier Transform Infrared Spectroscopy, SEMI MF1391-0704 for measuring substitutional carbon by Fourier Transform Infrared Spectroscopy, and SEMI MF1630-0704 for measuring dopants by low temperature Fourier Transform Infrared Spectroscopy. SEMI MF28-0707 can be used to indirectly measure the purity level using photoconductive decay. SEMI PV1-0309 can be used to measure a broad range of elemental impurities in 6N silicon feedstock by GDMS.

However, the existing SEMI test methods do not provide for the direct measurement of a broad range of elemental impurities in all grades in silicon feedstock including 7N-8N silicon feedstock. SEMI MF1724 states that the acid extraction of surface metal impurities on polysilicon can be extended to bulk digestion for the impurity collection and to inductively-coupled-plasma mass spectrometry (ICP-MS) for the analysis, but SEMI MF1724 does not provide a test method for those extensions. In addition SEMI MF 1724 is designed for alkali metals and first series transition elements using GF-AAS, not for a broader range of elements including dopants.

While the bulk digestion ICP-MS measurement of impurities in Si Feedstock is used commercially today, it is not possible to quantify the impact on the ROI if this standard is implemented.



b. Estimate effect on industry.
2: Major effect on an industry sector - identify the relevant sector
Sector or Company Information:

c. Estimate technical difficulty of the activity.
II: Some Difficulty - Disagreements on known requirements exist but developing consensus is possible

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2. Scope:
a: Describe the technical areas to be covered or addressed by this Document development activity. For Subordinate Standards, list common concepts or criteria that the Subordinate Standard inherits from the Primary Standard, as well as differences from the Primary Standard:
This document will provide a standard test method for the measurement of elemental impurity concentrations in Si Feedstock by bulk digestion Inductively-Coupled-Plasma Mass Spectrometry.

b: Expected result of activity
New Standard

For a new Subordinate Standard, identify the Primary Standard here:




For Standards, identify the Standard Subtype below:


Miscellaneous (describe below):

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3. Projected Timetable for Completion:

a: General Milestones
a. Activity Start: 10/16/2008b. 1st Draft by: 01/01/2009
c. (Optional) Informational Ballot by: d. Letter Ballot by: 01/01/2009
e. TC Chapter Approval By:04/01/2009

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4. Liaisons with other Global Technical Committees/TC Chapters/Subcommittees/TFs:
a.
List global technical committees, TC Chapters, subcommittees, or task forces in your or other Regions/Locales that should be kept informed regarding the progress of this activity. (Refer to SEMI Standards organization charts and global technical committee charters as needed.)
SEMI Si Wafer Committee
European SEMI PV Committee
Taiwan PV Working Group

b. Intercommittee Ballots:


Identify the recipient global technical committee(s):

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5. Safety Considerations:
The resulting document is expected:
NOT to be a Safety Guideline

NOTE FOR "to be a Safety Guideline": When all safety-related information is removed from the Document, the Document is NOT technically sound and complete - Refer to Section 14.1 of the Regulations for special procedures to be followed.

NOTE FOR "NOT to be a Safety Guideline": When all safety-related information is removed from the Document, the Document is still technically sound and complete.

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6. Intellectual Property Considerations:
a. For a new Standard or Safety Guideline and for any part to be modified or added in a Revision of published Standards and Safety Guidelines:
the use of patented technology or a copyrighted item(s) is NOT required

If "patented technology is intended to be included in the proposed Standard(s) or Safety Guideline(s) " is selected above, then also check one:


b. For Revision, Reapproval, Reinstatement, or Withdrawal of existing Standard(s) and Safety Guideline(s):


c. The body of the Document and any Appendices, Complementary Files, Related Information sections, or Various Materials that may or may not be a part of the Document by reference:
will NOT include copyrighted material



NOTE FOR "the use of patented technology or a copyrighted item(s) is NOT required": If in the course of developing the document, it is determined that patented technology or copyrighted item(s) must be used to comply with the standard or safety guideline, the provisions of Section 15 of the Regulations must be followed.)

NOTE FOR "will include reproduced copyrighted material": A copyright release letter must be obtained from the copyright owner.

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7. Comments, Special Circumstances:
None.

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8. TC Member Review:
None.

Member Review Start Date; None.
Member Review End Date: None.

NOTE FOR ‘TC Member Review’ is required by the Regulations for a period of at least two weeks
before approval of a new, or a major revision of an existing, Standard or Safety Guideline. (See Regulations 8.2.1)
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9.. SNARF Approval Dates:
TC Chapter or GCS10/15/2008
Recorded in TC Minutes
Attach Pictures and Files here: