Thermal Pad Heat Path for Wafer Edge Etch Uniformity
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Solution Overview
Problem
The etch rate variations in semiconductor wafers due to temperature differences between the edge and center, caused by heat retention in the insert ring during dry etching processes, result in inconsistent etching and structural height discrepancies.
Innovation Solution
A thermal pad is placed between the insert ring and the electrostatic chuck to dissipate heat from the wafer edge, ensuring consistent etch rates across the wafer by maintaining temperature uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thermal pad is added between the insert ring and electrostatic chuck to improve temperature uniformity, then etch rate uniformity is improved, but device complexity increases
Solution Approach 1:
A thermal pad is introduced as an intermediary component between the insert ring and electrostatic chuck. This thermal pad acts as a heat transfer mediator that conducts heat away from the wafer edge region, thereby improving temperature and etch rate uniformity across the wafer surface without requiring fundamental changes to the electrostatic chuck or insert ring designs.
2Temperature
If the electrostatic chuck cooling mechanisms are enhanced to reduce wafer edge heating, then temperature uniformity is improved, but use of energy increases
Solution Approach 1:
The thermal pad creates a passive heat conduction path that utilizes the existing temperature gradient between the heated wafer edge and the cooled electrostatic chuck. This self-driven heat flow requires no additional energy input, as the system leverages its own thermal gradient to achieve heat dissipation and temperature uniformity.
3Manufacturing precision
If the insert ring design is modified to improve heat dissipation, then etch rate uniformity is improved, but manufacturing precision of the insert ring increases
Solution Approach 1:
The heat dissipation function is segmented from the insert ring structure by introducing a separate thermal pad component. This allows the insert ring to maintain its original simple cylindrical design for easy manufacturing, while the thermal pad handles the thermal management function independently.
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 thermal pad enhances etch rate uniformity by effectively dissipating heat from the wafer edge, reducing etching time and minimizing structural height variations.
Implementation Method 1
one or more thermal pads are interposed between the insert ring and the electrostatic chuck... having a higher thermal conductivity than the shadow ring
Data Source
AI summary
Etch uniformity is improved by providing a thermal pad between an insert ring and electrostatic chuck in an etching chamber. The thermal pad provides a continuous passive heat path to dissipate heat from the insert ring and wafer edge to the electrostatic chuck. The thermal pad helps to keep the temperature of the various components in contact with or near the wafer at a more consistent temperature. Because temperature may affect etch rate, such as with etching hard masks over dummy gate formations, a more consistent etch rate is attained. The thermal pad also provides for etch rate uniformity across the whole wafer and not just at the edge. The thermal pad may be used in an etch process to perform gate replacement by removing hard mask layer(s) over a dummy gate electrode.