SEMI International Standards
SEMI New Activity Report Form (SNARF)

Activity Number: 4738
SNARF for: New Standard: Test Method for Contactless Carrier Recombination Lifetime in Silicon Wafers and Ingots using RF-Eddy-Current Sensing

Originating Global Technical Committee: Photovoltaic
Originating Technical Committee Region: North America
Task Force in which work is to be carried out: International PV Analytical Test Methods Task Force

1. Rationale: There are no international standards for minority-carrier lifetime measurement in PV silicon wafers or blocks. The measurement of lifetime in PV materials is quite mature, and existing semiconductor standards do not reflect the state-of-the-art understanding developed during the last 15 years in the PV field. The use of semiconductor wafer standards on PV material has technical problems and often contradicts best practice in the PV field. Some of the existing SEMI standards for the semiconductor industry are very particular to specific instruments and therefore not applicable to many of the lifetime measurement methods currently in widespread use.
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
I: No Difficulty - Proven concepts and techniques exist or quick agreement anticipated

2. Scope:
a: Define the areas to be covered or addressed by this activity or document:
The contactless measurement of minority-carrier lifetime in surface-passivated and unpassivated wafers, sections, and ingots using an RF-eddy-current sensor of excess carrier density.

b: Expected result of activity
New Standard

3. Projected Timetable for Completion:
a: General Milestones
a. Activity Start: 06/01/2009b. 1st Draft by: 12/01/2009
c. Preballot by: 03/01/2010d. Technical Ballot by: 05/01/2010
e. Committee Approval By:11/01/2010

Safety Considerations:
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: The project is anticipated to be difficult, because of the wide variety of materials quality and wafer types in PV silicon. Additionally, the bulk minority–carrier lifetime is generally not a directly measured quantity, but must be extracted from the instrument data using interpretation. This can lead to different values measured with different instruments or methodologies. Therefore, one goal of the standard would be to set rules sufficient to compare lifetimes as determined by different instruments, or to set a minimum set of requirements that could apply to many or most instruments.

A consensus may require a fairly broad minimum standard in contrast to a particular recipe standard.

Approval: Activity approved by Committee/GCS on July 16, 2009