SEMI International Standards
Standards New Activity Report Form (SNARF)
Date Prepared: 08/02/2012Revised (if Applicable): 10/29/2013

Document Number: 5506
SNARF for: New Standard: Guide for Measuring Flatness and Shape of Low Stiffness Wafers

Originating Global Technical Committee: 3DS-IC
Originating TC Chapter: North America
Task Force (TF) in which work is to be carried out: 3DS-IC Inspection and Metrology
Note: If a new task force is needed, also submit a task force organization form (TFOF)

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 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 gravity compensation.

Nowadays, however, the trend goes to use larger in diameter and thinner wafers, for instance in 3DS-IC applications. Larger and thinner wafers are less stiff than conventional ones. Low stiffness leads to a high deflection and sag, which can even exceed the required warp tolerance. In addition, the new applications require a complete depiction of the wafer’s shape, thus interpolation calculation methods based on few data points fail to depict the real free state of the wafer and allow passing failures like local bow.

The industry therefore would benefit from identifying a guide 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 guide will recommend the wafer to be characterized in a position that allows for a free state profile measurement on a semi-continuous flat mounting surface.

This revised SNARF changes the Draft Document from a “Test Method” to a “Guide”

b. Estimate effect on industry.
2: Major effect on an industry sector - identify the relevant sector
Sector or Company Information: producers of glass and silicon wafers, 3D-IC stacked device makers

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

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:
Establish a guide on how to measure wafers with a deflection of more than twice their warp tolerance. This guide can be applied to all materials and geometrical shapes.

b: Expected result of activity
New Standard or Safety Guideline (including replacement of an existing Standard or Safety Guideline)

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

For Standards, identify the Standard Subtype below:

Miscellaneous (describe below):

3. Projected Timetable for Completion:

a: General Milestones
a. Activity Start: 11/01/2012b. 1st Draft by: 04/01/2013
c. (Optional) Informational Ballot by: d. Letter Ballot by: 08/26/2014
e. TC Chapter Approval By:11/04/2014

4. Liaisons with other Global Technical Committees/TC Chapters/Subcommittees/TFs:
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.)
TC 3DS-IC (Bonded Wafer Stacks TF and Inspection & Metrology TF)
TC Silicon Wafer

Intercommittee ballots will be issued to: TC HB-LED, TC Silicon wafers, TC PIC, Assembly & Packaging

b. Intercommittee Ballots:
will be issued – identify the recipient global technical committee(s):

Identify the recipient global technical committee(s):
Assembly & Packaging, HB-LED, Physical Interfaces & Carriers, Silicon Wafer
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 15.1 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.

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 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):
there is no known material patented technology necessary to use or implement the 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 include reproduced 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 16 of the Regulations must be followed.)

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

7. Comments, Special Circumstances:
This guide will look at input of other committees, from HB-LED, PIC, and the silicon wafer committees

SNARF was first revised in October 29, 2012
SNARF was again revised in October 29, 2013 (change from Test Method to Guide)

SNARF was again revised at SEMICON West 2014. Approved via GCS on August 18, 2014.
SNARF title was updated. Previous title: "New Standard: Guide for Measuring Warp, Bow and TTV on Silicon and Glass Wafers Mounted on Wire Grids by Automated Non-Contact Scanning using Laser Scanning Interferometry"

8. TC Member Review:
took place between (put dates below ) before approval at the TC Chapter Meeting, or

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)
9.. SNARF Approval Dates:
TC Chapter or GCS08/18/2014
Recorded in TC Minutes
Attach Pictures and Files here: