Silicon Carbide Support Ring for Uniform Semiconductor Wafer Heating
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Solution Overview
Problem
Existing heat treatment apparatuses for semiconductor wafers experience non-uniform temperature distribution and vibrations during flash lamp annealing, leading to issues like particle creation and misregistration due to thermal expansion of temperature equalizing rings.
Innovation Solution
A heat treatment apparatus with a chamber, holder, and temperature equalizing ring design that uses silicon carbide or aluminum nitride materials, featuring inclined support members and a temperature equalizing ring with a reinforcing portion to suppress vibrations and ensure uniform heating, and a light shielding member to reduce thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a temperature equalizing ring is used to ensure uniform heating during preheating, then temperature uniformity is improved, but thermal expansion during flash irradiation causes vibrations and particle creation
Solution Approach 1:
The temperature equalizing ring is constructed from composite materials including silicon carbide, aluminum nitride, and graphite coated with silicon carbide. These materials provide both thermal management properties for uniform heating and mechanical stability to resist thermal expansion and vibrations during flash irradiation.
2Temperature
If the flash lamp irradiation time is extended to ensure thorough heating, then heating completeness is improved, but impurity diffusion increases beyond required depth
Solution Approach 1:
The system employs periodic action by using flash lamps to deliver intense heating in extremely short duration pulses (milliseconds or less). This pulsed heating approach ensures thorough heating and impurity activation while preventing excessive diffusion that would occur with prolonged continuous heating, thereby maintaining precise junction depth control.
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 apparatus achieves uniform heating of semiconductor wafers by minimizing temperature distribution disorders and preventing vibrations of the temperature equalizing ring, thus ensuring reliable substrate support and preventing particle creation and misregistration.
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, with only a small amount of light transmitted through the semiconductor wafer.
Implementation Method 2
a heat treatment apparatus which employs such xenon flash lamps is disclosed in U.S. Patent Application Publication No. 2009/0175605 in which flash lamps are disposed on the front surface side of a semiconductor wafer and halogen lamps are disposed on the back surface side thereof so that a desired heat treatment is performed using a combination of these lamps. In the heat treatment apparatus disclosed in U.S. Patent Application Publication No. 2009/0175605, a semiconductor wafer held on a susceptor is preheated to a certain degree of temperature by the halogen lamps.
Implementation Method 3
The quartz plate has an opening provided for a radiation therometer to measure the temperature of the semiconductor wafer therethrough.
Data Source
AI summary
Three support members made of silicon carbide are provided fixedly on an inner periphery of the support ring. The support members are inclined at an angle in the range of 15 to 30 degrees with respect to a horizontal plane. With an outer peripheral edge of a semiconductor wafer supported by the three support members, a heating treatment is performed by irradiating the semiconductor wafer with halogen light from halogen lamps. Silicon carbide absorbs the halogen light better than quartz. The support members support the outer peripheral edge of the semiconductor wafer in point contacting relationship, so that the contact between a holder and the semiconductor wafer is minimized. This minimizes the disorder of the temperature distribution of the semiconductor wafer due to the support members to achieve the uniform heating of the semiconductor wafer.