Partitioned Polishing Head for Wafer Edge Pressure Control
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Solution Overview
Problem
Conventional single-side polishing apparatuses with rubber chuck type polishing heads face difficulties in controlling the polishing surface pressure applied to the outer peripheral portion of the workpiece, leading to inconsistent polishing results.
Innovation Solution
The polishing head features a ring-shaped member with a partitioned space, allowing independent control of gas introduction into the central and outer peripheral regions, thereby enabling precise adjustment of polishing surface pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If gas is introduced into a single undivided space behind the membrane to inflate it, then the workpiece can be pressed against the polishing pad, but the polishing surface pressure applied to the outer peripheral portion of the workpiece becomes difficult to control
Solution Approach 1:
The single undivided space behind the membrane is divided into a central region and an outer peripheral region by a partition structure. This segmentation allows independent gas introduction into each region, enabling separate control of polishing surface pressure in the central and outer peripheral portions of the workpiece, thereby resolving the difficulty of controlling pressure distribution across the entire surface.
2Productivity
If the polishing surface pressure on the outer peripheral portion is not properly controlled, then the polishing process can proceed, but the polishing amount of the outer peripheral portion becomes inconsistent
Solution Approach 1:
Different regions of the polishing space are given different functional qualities through the partition structure. The central region and outer peripheral region can have different gas pressures applied independently, allowing each region to be optimized for its specific polishing requirements. This local quality differentiation ensures uniform polishing amount across the entire workpiece surface while maintaining efficient polishing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for easy and precise control of the polishing surface pressure on the outer peripheral portion of the workpiece, improving the consistency and accuracy of the polishing process.
Implementation Method 1
gas such as air is introduced into a space behind a membrane (a rubber film in Japanese Patent Application Publication No. 2008-110407) so that the membrane is inflated, thereby a workpiece can be pressed via a back pad (backing pad in Japanese Patent Application Publication No. 2008-110407) which is located below the membrane
Data Source
AI summary
A polishing head includes a first ring-shaped member having an opening; a plate-shaped member that closes the opening on an upper side of the first ring-shaped member; a membrane that closes the opening on a lower side of the first ring-shaped member; a back pad adhered to a lower surface of the membrane; and a second ring-shaped member located below the back pad and having an opening that holds a polishing target workpiece. A space formed by closing the opening of the first ring-shaped member by the plate-shaped member and the membrane includes: a central region; and an outer peripheral region partitioned from the central region by a partition, and an inner peripheral edge region of the second ring-shaped member is located vertically below an outer peripheral edge of the outer peripheral region. A polishing apparatus includes the polishing head, and is used in a method of manufacturing a semiconductor wafer.