Polishing Head Annular Partition Wall for Wafer Uniformity
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Solution Overview
Problem
Existing semiconductor wafer polishing technologies suffer from in-plane fluctuations in polishing amounts, leading to non-uniform surfaces, particularly with the two-zone membrane head system.
Innovation Solution
A polishing head design featuring a first annular member, a closing member, a membrane, and a second annular member, partitioned by an annular partition wall with specific diameter and radius ratios, and gas introduction paths to control surface pressure and enhance in-plane uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a two-zone membrane head is used to press the workpiece, then the workpiece can be held and pressed against the polishing pad, but in-plane fluctuations in polishing amount occur at the surface to be polished
Solution Approach 1:
The membrane is divided into multiple independent zones (first membrane zone and second membrane zone) with different pressing forces. Each zone can be controlled independently to apply different pressures to different regions of the workpiece, thereby eliminating in-plane fluctuations in polishing amount while maintaining overall pressing force.
Solution Approach 2:
Different regions of the membrane are designed with different properties - the first membrane zone has different pressing force characteristics compared to the second membrane zone. This local differentiation allows optimization of pressing force distribution across the workpiece surface, improving polishing uniformity without sacrificing total pressing force.
2Force
If gas is introduced into the space at the back surface of the membrane to swell it, then the workpiece can be pressed, but in-plane fluctuations in polishing amount are caused
Solution Approach 1:
The gas introduction system is segmented into multiple independent channels corresponding to different membrane zones. Gas can be introduced into each zone separately with different flow rates and pressures, allowing independent control of swelling and pressing force in each region to achieve uniform polishing.
Solution Approach 2:
The pressing force in different membrane zones is controlled by adjusting gas introduction parameters (flow rate, pressure, timing) for each zone. By changing these parameters independently for the first and second membrane zones, uniform pressing force distribution is achieved across the workpiece surface.
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
The design significantly reduces in-plane fluctuations and enhances the uniformity of the polishing amount across the semiconductor wafer surface, improving the polishing process.
Implementation Method 1
by introducing a gas such as air into the space at the back surface of a membrane (which is referred to as a rubber film in Japanese Patent No. 4833355), and thereby swelling the membrane, it is possible to press the work
Data Source
AI summary
The polishing head has, with the direction toward the center of the opening of the first annular member assumed as the inside, and with the other direction assumed as the outside, the space, formed by closing the opening of the first annular member by the closing member and the membrane, and partitioned into an inside space and an outside space by an annular partition wall with a top annular connection part connected to the closing member and with a bottom annular connection part connected to the membrane, the inside diameter of the bottom annular connection part of the annular partition wall is larger than the inside diameter of the second annular member, and the radius of the top annular connection part of the annular partition wall is 33% or more and 90% or less with the radius of the setting position of the work to be polished assumed as 100%.