Polysilicon Deposition via BCl3 Doping for Low Resistivity
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Solution Overview
Problem
Current chemical vapor deposition (CVD) processes for depositing thick, low-resistivity polycrystalline silicon layers face challenges in achieving high throughput, uniformity, and low electrical resistance, particularly for through-wafer-vias, due to limitations in deposition temperature and precursor efficiency.
Innovation Solution
A CVD method using a temperature range of 605°C-800°C with silane (SiH4) or dichlorosilane (SiH2Cl2) as the silicon source gas and boron trichloride (BCl3) as the dopant gas, improving deposition rates and uniformity, and enabling low resistivity polysilicon growth above 620°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperature CVD process (above 620°C) is used to increase deposition rate, then productivity is improved, but manufacturing precision deteriorates due to poor uniformity and inability to achieve low resistivity
Solution Approach 1:
The patent changes the chemical parameters of the CVD process by using boron trichloride (BCl3) as the dopant precursor instead of traditional diborane (B2H6), and uses dichlorosilane (SiH2Cl2) as the silicon precursor. This chemical parameter change enables the process to achieve both high deposition rates and low resistivity at temperatures above 620°C, resolving the contradiction between productivity and manufacturing precision.
2Manufacturing precision
If low temperature CVD process (below 620°C) is used to achieve low resistivity, then manufacturing precision is improved, but productivity deteriorates due to low deposition rate
Solution Approach 1:
The patent employs boron trichloride as the dopant precursor, which fundamentally changes the deposition chemistry. This enables the process to achieve low resistivity (below 0.01 ohm-cm) at temperatures above 620°C with deposition rates exceeding 15 nm/min, simultaneously improving both manufacturing precision and productivity compared to traditional low-temperature processes.
3Productivity
If high temperature process (above 620°C) is used to increase throughput, then productivity is improved, but manufacturing precision deteriorates because nearly 100% of silane is consumed causing poor uniformity
Solution Approach 1:
The patent uses dichlorosilane (SiH2Cl2) as the silicon precursor instead of silane (SiH4). This chemical parameter change results in more controlled precursor consumption and deposition kinetics, achieving both high throughput and excellent layer uniformity at temperatures above 620°C, thereby resolving the contradiction between productivity and manufacturing precision.
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 method achieves high deposition rates of over 15 nm/min, reduces deposition time and costs, and ensures very low and uniform resistivity in the grown layers, suitable for forming low-resistance through-wafer-vias, enhancing the manufacturing of semiconductor devices and MEMS applications.
Implementation Method 1
A CVD method using a temperature range of 605°C-800°C with silane (SiH4) or dichlorosilane (SiH2Cl2) as the silicon source gas
Implementation Method 2
boron trichloride (BCl3) as the dopant gas, improving deposition rates and uniformity, and enabling low resistivity polysilicon growth above 620°C
Data Source
Figure 1
Figure 2a~3b
Figure 4~5
AI summary
The invention relates to a method for depositing one or more polycrystalline silicon layers (230c) on a substrate (210) by a chemical vapour deposition in a reactor, which method comprises adjusting a deposition temperature between 605 °C-800 °C in a process chamber of the reactor, and depositing the one or more polycrystalline silicon layers on the substrate by using a silicon source gas comprising SiH4 or SiH2CI2, and a dopant gas comprising BCI3.