Oscillating Radiant Heat Sources for Wafer Temperature Uniformity
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Solution Overview
Problem
Radiant heating systems in semiconductor manufacturing often result in non-uniform temperature distributions across wafers due to hot and cold spots, which can lead to inconsistent deposition and operation characteristics in CVD processes, despite the use of reflectors and wafer rotation to mitigate these issues.
Innovation Solution
The implementation of movable radiant heat sources that oscillate along a path less than 10 mm from the geometric center or change angular positions to illuminate different areas on the wafer, blurring the edges of hot and cold spots and smoothing out intensity profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If radiant heating is used to heat wafers quickly, then processing time is reduced and throughput is improved, but temperature uniformity deteriorates due to hot and cold spots
Solution Approach 1:
The patent applies the dynamics principle by making the radiant heat sources movable rather than stationary. The heat sources oscillate along a path less than 10 mm from the geometric center, continuously changing their position to illuminate different areas of the wafer. This dynamic movement redistributes the radiant energy over time, eliminating static hot and cold spots while maintaining rapid heating capability for high throughput processing
2Temperature
If reflectors are added to distribute radiant energy, then temperature uniformity is improved, but device complexity increases
Solution Approach 1:
Instead of adding complex static reflector systems, the patent uses a dynamic approach where simple movable heat sources replace the need for complex reflector geometries. The oscillation mechanism is simpler than designing and positioning multiple reflectors, reducing overall device complexity while achieving temperature uniformity through temporal redistribution of radiant energy
3Temperature
If wafer rotation is used to reduce temperature non-uniformities, then temperature uniformity is improved, but processing time increases
Solution Approach 1:
The patent applies dynamics by moving the heat sources instead of rotating the wafer. This approach achieves temperature uniformity more quickly because the heat sources can be positioned and oscillated independently of wafer rotation mechanics. The rapid oscillation of heat sources redistributes energy faster than wafer rotation can equalize temperatures, reducing the time penalty associated with rotation-based uniformity correction
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 approach significantly improves temperature uniformity across the wafer, reducing hot and cold spots and enhancing the consistency of deposition processes, leading to more uniform processing results.
Implementation Method 1
Radiant heating energy can be supplied, for example, by banks of infrared (IR) lamps (e.g., quartz halogen lamps) above and/or below the wafer in the reaction chamber.
Implementation Method 2
At least one of the radiant heat sources is movable during processing in an oscillatory motion along a path less than about 10 mm from a geometric center of the oscillatory motion.
Data Source
AI summary
A semiconductor processing apparatus including a processing chamber and a plurality of radiant heat sources. The radiant heat sources heat a workpiece within the chamber. At least one of the radiant heat sources is movable during processing in an oscillatory motion along a path less than about 10 mm from a geometric center of the oscillatory motion.