SEMI International Standards
SEMI New Activity Report Form (SNARF)



Activity Number: 5506
SNARF for: New Standard: Test Method for Measuring Warp, Bow and TTV on Silicon and Glass Wafers Mounted on Wire Grids by Automated Non-Contact Scanning using Laser Scanning Interferometry


Originating Global Technical Committee: 3DS-IC
Originating Technical Committee Region: North America
Task Force in which work is to be carried out: 3DS-IC Inspection and Metrology


1. Rationale: The current metrology strategies have evolved from methods used to characterize smaller, lower aspect ratio geometries. Conventionally, three point mounts have been used to measure flatness/warp of wafer along with the gravity compensation.

For instance 3DS-IC applications use larger and thinner wafers than conventional applications. Large, thin wafers have inherently low stiffness, leading to large deflections, which make compensation more challenging. Ball mounts cause large deflections, 4-point and ring supports have redundant support and are sensitive to how parts are placed on the mount.

The industry therefore would benefit from identifying an alternate test method that better reflects the application usage of these wafers. One such approach used in the industry is a similar set up to Sori with a wire mount and a noncontact scanning method that allows depicting a complete picture of the wafer’s shape and dimensional parameters.
This method will recommend the wafer to be characterized in a position that allows for a free state profile measurement on a flat surface.
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

2. Scope:
a: Define the areas to be covered or addressed by this activity or document:
Describe a test method that accurately and reliably depicts the dimensional shape of single silicon and glass wafers that are ≥ 300 mm in diameter and ≤ 775 µm in thickness and that uses a wire mount and Laser scanning interferometry.
The document will include applicable ranges for valid measurements where possible.

b: Expected result of activity
New Standard

3. Projected Timetable for Completion:
a: General Milestones
a. Activity Start: 11/01/2012b. 1st Draft by: 04/01/2013
c. Preballot by: d. Technical Ballot by: 05/01/2013
e. Committee Approval By:07/01/2013




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: This specification will look at input of other committees, from HB-LED, PIC, and the silicon wafer committees

Approval: Activity approved by Committee/GCS on October 30, 2012