Polycrystalline Silicon Resistance Elements with Controlled TCR
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Solution Overview
Problem
Semiconductor devices with resistance elements experience performance deterioration due to significant changes in resistance value caused by temperature variations, primarily attributed to the temperature coefficient of resistance (TCR) of polycrystalline silicon elements, which can vary widely based on impurity concentration and width, leading to instability and inaccuracies in circuit operations.
Innovation Solution
The implementation of polycrystalline silicon resistance elements with specific impurity concentrations and widths, where the impurity concentration is set at sign change points of the TCR to minimize the absolute value of TCR, allowing for the formation of groups of polycrystalline silicon elements with controlled TCR values, either by electrical series or parallel connection, to stabilize resistance values and performance across temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polycrystalline silicon resistance elements are used in semiconductor devices, then resistance elements can be formed with controlled resistance values, but the resistance value changes significantly with temperature due to high temperature coefficient of resistance (TCR)
Solution Approach 1:
The patent applies parameter changes by precisely controlling the impurity concentration in polycrystalline silicon to specific ranges (e.g., 1×10^19 to 1×10^20 atoms/cm³) to minimize the temperature coefficient of resistance. By adjusting this critical parameter, the TCR is reduced to below ±50 ppm/°C, thereby stabilizing the resistance value across temperature variations without changing the fundamental material or structure.
Solution Approach 2:
The patent implements local quality by creating regions with different impurity concentrations within the polycrystalline silicon resistance element. Specifically, it forms a first region with impurity concentration of 1×10^19 to 1×10^20 atoms/cm³ and a second region with 1×10^20 to 1×10^21 atoms/cm³, allowing different parts of the same element to have optimized properties for minimizing TCR while maintaining overall performance.
2Manufacturing precision
If impurity concentration in polycrystalline silicon is increased to control resistance value, then resistance value can be adjusted, but temperature coefficient of resistance (TCR) increases leading to performance deterioration
Solution Approach 1:
The patent optimizes the impurity concentration parameter to a specific range (1×10^19 to 1×10^20 atoms/cm³) that simultaneously achieves precise resistance control and minimizes TCR. This precise parameter optimization ensures that resistance values can be manufactured with high precision while maintaining performance stability across temperature variations.
Solution Approach 2:
The patent uses partial action by forming a first region with lower impurity concentration (1×10^19 to 1×10^20 atoms/cm³) specifically optimized for low TCR, while a second region with higher concentration (1×10^20 to 1×10^21 atoms/cm³) provides additional resistance control. This partial optimization of different regions achieves both precision and stability.
Data Source
AI summary
A semiconductor device includes as a resistance element a first polycrystalline silicon and a second polycrystalline silicon containing impurities, such as boron, of the same kind and having different widths. The first polycrystalline silicon contains the impurities at a concentration CX. The second polycrystalline silicon has a width larger than a width of the first polycrystalline silicon and contains the impurities of the same kind at a concentration CY lower than the concentration CX. A sign of a temperature coefficient of resistance (TCR) of the first polycrystalline silicon changes at the concentration CX. A sign of a TCR of the second polycrystalline silicon changes at the concentration CY.