Flash Lamp Annealing Support Pin Radius Adjustment
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Solution Overview
Problem
Flash lamp annealing causes rapid temperature increase on the front surface of semiconductor wafers, leading to warping and stress concentration on the back surface, resulting in cracking during flash-light irradiation.
Innovation Solution
A heat treatment apparatus with a susceptor having support pins whose positions adjust based on the pulse width of the flash light, with the radius of the setting circle for the pins increasing as the pulse width decreases, to distribute support and reduce stress on the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If flash light energy is enhanced to rapidly heat the front surface of the semiconductor wafer, then the temperature rise speed is improved, but stress concentration occurs in the back surface causing cracking
Solution Approach 1:
The support pin positions are dynamically adjusted based on the flash light pulse width. For shorter pulse widths (faster heating), pins are positioned closer to the center to provide stronger support where thermal stress concentrates. For longer pulse widths, pins are positioned farther from the center. This dynamic adaptation allows the system to maintain wafer integrity across different heating rates.
Solution Approach 2:
The invention changes the positional parameters of the support pins according to the pulse width parameter of the flash light. By establishing a correspondence between pulse width and pin position, the system optimizes support configuration for each heating condition, preventing stress concentration-induced cracking while maintaining high temperature rise speed.
2Productivity
If flash light irradiation is applied to activate impurities in the semiconductor wafer, then the activation efficiency is improved, but the wafer surface warps due to differential thermal expansion
Solution Approach 1:
The support pins are pre-positioned according to the expected pulse width before flash light irradiation begins. This preliminary configuration ensures that adequate support is in place during the critical heating phase, preventing warping from occurring in the first place while allowing efficient impurity activation.
3Loss of time
If the pulse width of flash light is reduced to achieve selective surface heating, then the activation temperature is reached faster, but the thermal stress concentration increases causing potential cracking
Solution Approach 1:
The support pin configuration is locally optimized for each pulse width condition. By positioning pins at specific radii corresponding to different pulse widths, the system provides localized support exactly where thermal stress concentrates during ultrafast heating, enabling short pulse widths to be used safely for rapid activation.
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 prevents cracking of the semiconductor wafer by adjusting the support pin positions according to the flash light pulse width, effectively managing the thermal expansion and stress during flash-light irradiation.
Implementation Method 1
The wavelength of light emitted from the xenon flash lamps is shorter than that of light emitted from conventional halogen lamps, and approximately coincides with a fundamental absorption band of a silicon semiconductor wafer. Thus, when a semiconductor wafer is irradiated with a flash of light emitted from the xenon flash lamps, the temperature of the semiconductor wafer can be raised rapidly
Implementation Method 2
only the front surface of the semiconductor wafer thermally expands rapidly, so that the semiconductor wafer is deformed so as to warp in such a manner that its front surface becomes convex
Data Source
AI summary
A plurality of substrate support pins are erected on a susceptor that holds a semiconductor wafer that is an object being treated. The plurality of substrate support pins are set in a ring shape at equal intervals. A flash lamp irradiates the semiconductor wafer supported by the plurality of substrate support pins with flash light to heat the semiconductor wafer. The radius of a setting circle in which the plurality of substrate support pins are set is made larger as the pulse width of flash light emitted from the flash lamp decreases. To irradiate the semiconductor wafer with flash light while having the semiconductor wafer supported by the plurality of substrate support pins can prevent cracking of the semiconductor wafer despite possible abrupt deformation of the semiconductor wafer due to the flash-light irradiation.