Polysilicon Resistive Layer Boron Concentration Profile
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Solution Overview
Problem
In semiconductor devices, increasing the boron dose to achieve a temperature coefficient close to zero results in a low sheet resistance value, leading to larger chip sizes and increased costs, hindering circuit integration.
Innovation Solution
A semiconductor device with a resistive layer made of polycrystalline silicon containing boron, featuring a concentration distribution with a peak and a low concentration portion, where the boron concentration in the low portion is two orders of magnitude lower than in the peak, is manufactured by implanting boron and subsequent annealing, allowing for a high sheet resistance value and controlled temperature coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the boron dose is increased to achieve a temperature coefficient close to zero, then the temperature coefficient is improved, but the sheet resistance value decreases
Solution Approach 1:
The patent applies local quality by creating a non-uniform boron concentration distribution within the resistive layer. Specifically, a high-concentration boron region is formed at a predetermined depth from the surface, while other regions maintain lower concentrations. This localized doping strategy allows the high-concentration region to provide low temperature coefficient characteristics, while the overall layer structure maintains higher sheet resistance values, thus resolving the contradiction between improving temperature coefficient and maintaining sheet resistance.
2Reliability
If the sheet resistance value becomes low, then the temperature coefficient approaches 0, but the resistive element area becomes large
Solution Approach 1:
The patent creates a localized high-concentration boron region at a specific depth within the resistive layer, rather than uniformly doping the entire layer. This localized doping approach allows the high-concentration region to provide the low temperature coefficient effect, while the limited volume of this region prevents a significant decrease in overall sheet resistance, thereby avoiding the need for large resistive element areas.
3Reliability
If the sheet resistance value becomes low, then the temperature coefficient approaches 0, but the chip size increases
Solution Approach 1:
The patent implements local quality by forming a concentrated boron-doped region at a predetermined depth from the surface of the resistive layer. This localized high-concentration region provides the necessary low temperature coefficient characteristics without requiring a large overall doping volume, thereby maintaining higher sheet resistance values and enabling smaller chip sizes.
4Reliability
If the sheet resistance value becomes low, then the temperature coefficient approaches 0, but the cost increases
Solution Approach 1:
The patent applies local quality by creating a focused high-concentration boron region at a specific depth within the resistive layer. This localized doping strategy achieves the low temperature coefficient effect with a smaller total boron dose and reduced resistive element area, thereby lowering material costs and manufacturing expenses compared to uniform doping approaches.
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 enables a semiconductor device with a low temperature coefficient and high sheet resistance value, reducing chip size and cost while maintaining high circuit integration.
Implementation Method 1
a step of introducing boron into the resistive layer
Implementation Method 2
a step of annealing the resistive layer in order to activate the boron introduced into the resistive layer
Data Source
AI summary
A semiconductor device capable of lowering a temperature coefficient and increasing a sheet resistance value (ρs value) and a manufacturing method thereof are provided. The resistive layer RL is made of polycrystalline silicon containing boron. The concentration distribution of boron in the thickness direction of the resistive layer RL includes a concentration peak PC and a low concentration portion LC having a concentration of boron lower than the concentration of boron in the concentration peak PC by two orders of magnitude or more.