SEMI M77 - Test Method for Determining Wafer Near-Edge Geometry Using Roll-Off Amount, ROA
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 31, 2015. Available at www.semiviews.org and www.semi.org in October 2015; originally published November 2010.
Wafer near-edge geometry can significantly affect the yield of semiconductor device processing.
Knowledge of near-edge geometrical properties can help the producer and consumer determine if the dimensional characteristics of a specimen wafer satisfy given geometrical requirements.
The ROA metric is suitable for quantifying near-edge geometry of wafers used in semiconductor device processing.
Consideration should be given to the use of this or other proposed edge geometry metrics as a process control tool rather than a material exchange specification.
This Test Method covers calculation of the near-edge geometry metric roll-off amount (ROA).
Calculation of ROA is based on height data that are representative of a height data profile associated with one or more of the front surface, the back surface, or thickness.
This Test Method covers selection of the point at which the ROA is determined and the reference line to be utilized for this determination.
This Test Method is applicable to categories of wafers specified in SEMI M1 used in advanced IC manufacturing.
This Test Method has been shown to be suitable for quantifying near-edge geometry to improve CMP performance at wafer edge. ROA values in that study were measured using an edge-referenced coordinate system. On the other hand, measurement systems for high volume production geometry (e.g., whole-wafer flatness) use a center-referenced coordinate system.
This Test Method allows for the use of either an edge-referenced or a center-referenced coordinate system.
There are other metrics for near-edge geometrical properties, some of which quantify more specific aspects. These are outside the scope of this practice.
This Test Method does not cover acquisition of the height data array. However, it gives the required characteristics of the height data array.
Referenced SEMI Standards
SEMI M1 — Specifications for Polished Single Crystal Silicon Wafers
SEMI M20 — Practice for Establishing a Wafer Coordinate System
SEMI M59 — Terminology for Silicon Technology
SEMI M67 — Test Method for Determining Wafer Near-Edge Geometry from a Measured Thickness Data Array Using the ESFQR, ESFQD, and ESBIR Metrics
SEMI M68 — Test Method for Determining Wafer Near-Edge Geometry from a Measured Height Data Array Using a Curvature Metric, ZDD
SEMI M70 — Test Method for Determining Wafer Near-Edge Geomtry Using partial Wafer Site Flatness