Wafer Heater with Heat Dispersion Layer for Uniform Baking
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Solution Overview
Problem
Existing wafer baking apparatuses face challenges in achieving uniform temperature distribution across semiconductor wafers, leading to non-uniform photoresist layer thickness and potential device defects due to variations in solvent evaporation during the baking process.
Innovation Solution
A wafer baking apparatus is designed with a heating system comprising a first and second heating plate, where a heat dispersion layer with lower thermal conductivity than the plates is interposed between them, and a heating resistance pattern on the lower surface of the first heating plate, allowing for independent temperature control of heating sectors and uniform heat distribution through an air gap or heat-resistant adhesive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional heating plate is used without a heat dispersion layer, then the heating structure is simple, but the temperature distribution across the wafer is non-uniform
Solution Approach 1:
A heat dispersion layer is introduced as an intermediary component between the heating plate and the wafer. This layer has higher thermal conductivity than the heating plate material, acting as a thermal mediator to redistribute heat laterally and eliminate temperature non-uniformities across the wafer surface.
Solution Approach 2:
The heating system uses a composite structure combining a heating plate made of one material (e.g., stainless steel or aluminum) with a heat dispersion layer made of a different material having superior thermal conductivity (e.g., copper or graphite). This composite arrangement leverages the advantages of both materials to achieve uniform temperature distribution.
2Temperature
If the thermal conductivity of the heat dispersion layer is high, then temperature uniformity is improved, but heat loss from the heating plate increases
Solution Approach 1:
The thermal conductivity parameter of the heat dispersion layer is carefully selected and optimized. The layer has higher thermal conductivity than the heating plate to achieve temperature uniformity, but not excessively high to avoid significant heat loss. This parameter optimization balances temperature uniformity with energy efficiency.
3Ease of operation
If a single heating plate is used, then the device structure is simple, but independent temperature control of different heating sectors is not possible
Solution Approach 1:
The heating plate is divided into multiple independent heating sectors, each with its own heating element or resistance pattern. This segmentation allows independent temperature control of different regions, enabling precise thermal management for different areas of the wafer during the baking process.
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 ensures a uniform temperature distribution across the wafer, reducing temperature deviations to less than 0.1°C and achieving consistent photoresist layer thickness, thereby enhancing semiconductor device performance and reliability.
Implementation Method 1
a heating resistance pattern disposed on a lower surface of the first heating plate
Implementation Method 2
a heat dispersion layer interposed between the first heating plate and the second heating plate, and having a thermal conductivity that is lower than a thermal conductivity of materials of the first heating plate and the second heating plate
Data Source
AI summary
A wafer baking apparatus includes a chamber including a processing space, and a wafer heater disposed in the processing space and configured to support a wafer. The wafer heater includes a first heating plate, a heating resistance pattern disposed on a lower surface of the first heating plate, a second heating plate disposed on the first heating plate, and a heat dispersion layer interposed between the first and second heating plates and having thermal conductivity lower than a thermal conductivity of materials of the first and second heating plates.