Segmented Wafer Heater for Uniform Thermal Control
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Solution Overview
Problem
Heaters used for large-diameter semiconductor wafers face challenges with thermal stress, warpage, and reduced positioning accuracy, leading to non-uniform heating and increased maintenance needs due to their large size and thermal expansion.
Innovation Solution
A heater design featuring multiple elements arranged rotationally symmetrically around a shaft, with electrodes and wiring components that allow for stable and uniform heating by maintaining a constant distance between elements, reducing thermal stress and warpage, and enabling precise temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a large-diameter heater is used to heat large-diameter wafers, then the heating area is increased, but thermal stress and warpage increase causing damage and reduced positioning accuracy
Solution Approach 1:
The heater is divided into multiple independent heating elements arranged in a circular pattern around the wafer center. Each element can be independently controlled and positioned, allowing the large heating area to be achieved while maintaining individual element stability and reducing overall thermal stress and warpage.
2Area of stationary object
If heater elements are made larger to cover large-diameter wafers, then the heating coverage is improved, but positioning accuracy deteriorates due to warpage
Solution Approach 1:
The heater is segmented into multiple smaller heating elements rather than using a single large element. This segmentation allows each element to maintain dimensional stability and positioning accuracy while collectively providing coverage for large-diameter wafers through their distributed arrangement.
Solution Approach 2:
The heating elements are arranged in a circular pattern around the wafer center, transitioning from a single-plane large element to a multi-dimensional circular configuration. This dimensional change allows coverage of large wafer areas while maintaining precise positioning of individual elements through radial and angular placement.
3Device complexity
If a single large heater element is used, then the structure is simple, but thermal stress causes damage and increased maintenance
Solution Approach 1:
The heater is divided into multiple independent elements that can expand and contract independently under thermal stress. This segmentation distributes thermal stress across multiple smaller units rather than concentrating it in a single large element, preventing damage and reducing maintenance requirements.
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 design ensures uniform film thickness and reduced maintenance frequency by minimizing thermal stress and warpage, while allowing for high-precision temperature control and stable production of large-diameter heaters.
Implementation Method 1
heating the wafer by causing a heater to generate heat through voltage application from an electrode provided at each center portion of elements forming the heater
Implementation Method 2
heater members made of SiC, for example, thermally expand. Stress is put on fixed portions due to thermal stress
Data Source
AI summary
A heater for heating a wafer includes elements that are arranged at a distance from one another in a rotationally symmetrical fashion with respect to a shaft extending through a center of the wafer, an electrode being provided to each of the elements to heat the wafer uniformly.