Polycrystalline SiC Body With Uniform Resistivity
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Solution Overview
Problem
Polycrystalline SiC formed bodies used in semiconductor production devices often exhibit variations in resistivity across their thickness, leading to reduced device throughput and the need for adjustments in driving conditions.
Innovation Solution
A polycrystalline SiC formed body with a resistivity of 0.050 Ωcm or less and a nitrogen content of 200 ppm or more, produced using a CVD method where the concentration of nitrogen atom-containing compound gas is increased at a constant rate during film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CVD method is used to form polycrystalline SiC, then film formation is achieved, but resistivity varies in the thickness direction causing reduced device throughput
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the nitrogen-containing gas concentration during the CVD film formation process. The gas concentration is increased from the beginning of film formation to the end, which changes the doping profile through the thickness of the film and achieves uniform resistivity distribution, thereby resolving the contradiction between manufacturing precision and productivity.
Solution Approach 2:
The patent implements preliminary action by introducing nitrogen-containing gas throughout the entire film formation process rather than adding it after formation. This preliminary doping action ensures that resistivity uniformity is built into the film structure during growth, eliminating the need for post-formation adjustments and maintaining high device throughput.
2Reliability
If nitrogen is added to reduce resistivity, then low resistivity is achieved, but resistivity variation in thickness direction increases
Solution Approach 1:
The patent uses parameter changes by controlling the temporal profile of nitrogen-containing gas concentration during CVD film formation. By increasing the gas concentration from start to end of film formation, the doping is optimized to achieve both low resistivity (0.050 Ωcm or less) and uniform resistivity distribution in the thickness direction (peak intensity ratio difference of 0.040 or less).
Solution Approach 2:
The patent applies dynamics by making the nitrogen gas concentration variable rather than constant during the film formation process. This dynamic adjustment allows the doping profile to adapt to the changing conditions during film growth, achieving uniform resistivity while maintaining low overall resistivity values.
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 approach results in a polycrystalline SiC formed body with low and uniform resistivity across its thickness, enhancing the stability and efficiency of semiconductor production devices.
Implementation Method 1
a polycrystalline SiC formed body is obtained by precipitating polycrystalline SiC on a surface of a substrate by the CVD method
Implementation Method 2
introducing a nitrogen atom-containing compound gas together with a raw material gas and a carrier gas into a reaction chamber; and increasing a concentration of the nitrogen atom-containing compound gas at a constant rate from a start of film formation to an end of the film formation
Data Source
AI summary
The present invention provides a polycrystalline SiC formed body having a low resistivity and a small variation in resistivity in a thickness direction thereof, and a method for producing the same. In the polycrystalline SiC formed body, a resistivity is 0.050 Ωcm or less, and an average value of peak intensity ratios (A/B) is 0.040 or less, and a difference between an average of peak intensity ratios on a growth surface side and an average of peak intensity ratios on a substrate surface side is 0.040 or less, wherein “A” represents a peak intensity within a range of wavenumber of 950 to 970 cm−1 of a Raman spectrum and “B” represents a peak intensity within a range of wavenumber of 780 to 800 cm−1 in a Raman spectrum.