SEMI M73 - Test Method for Extracting Relevant Characteristics from Measured Wafer Edge Profiles
This Standard was technically approved by the Silicon Wafer Global Technical Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on August 22, 2013. Available at www.semiviews.org and www.semi.org in October 2013. Originally published November 2008; previously published March 2009.
SEMI M1 specifies the contour of the shaped edge of silicon wafers by using templates that allow a wide variation in wafer edge profiles manufactured by silicon suppliers to still meet the specification.
In many advanced wafer applications, a much tighter specification of the edge profile is required to control variations in subsequent circuit processing. These specifications frequently include values for certain characteristics that describe the segments of the edge profile contour.
A prerequisite for specifying tighter tolerances on edge profiles is an agreement about the names of the relevant characteristics used for describing edge profiles and a method for extracting these characteristics from a measured edge profile. Therefore in these test methods, terms used to describe the characteristics of the edge profile of silicon wafers are named and their meaning is illustrated by a schematic drawing.
This Standard covers two test methods for deriving these characteristics from a measured edge profile.
These test methods are both in use within the industry. They are based on fitting the measured edge profile over certain segments with straight lines, circular arcs, or tangent lines to obtain values for profile segment parameters such as:
• bevel angles,
• edge widths,
• apex lengths,
• apex angles, and
• shoulder radii.
In addition, the locations of the reference points that separate the various segments of the edge profile are determined. These segment parameters are listed in order around the profile in Table 1 and are illustrated in Figure 1.
Referenced SEMI Standards
SEMI M1 — Specification for Polished Single Crystal Silicon Wafers
SEMI M20 — Practice for Establishing a Wafer Coordinate System
SEMI M59 — Terminology for Silicon Technology