Doped Polysilicon Layer Formation via Segmented Deposition and High-Temperature Diffusion
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Solution Overview
Problem
Current methods for forming doped polysilicon layers face challenges in controlling layer thickness, dopant uniformity, and deposition rate, particularly when aiming for higher deposition rates and thicker layers, which are essential for advanced semiconductor applications.
Innovation Solution
A method involving a deposition cycle where a silicon-containing precursor is used to form an undoped silicon layer, followed by a flow of dopant precursor gas without the precursor, and a heat treatment process to form a doped polysilicon layer, allowing for higher growth temperatures and thicker layers with uniform dopant distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If in-situ doping is performed during polysilicon deposition, then doping and deposition can be combined in one process, but control of layer thickness, dopant uniformity, and deposition rate becomes difficult
Solution Approach 1:
The process is divided into two separate stages: first, depositing an undoped polysilicon layer to the desired thickness, and second, performing doping on the already-formed layer. This segmentation allows independent optimization of deposition parameters for thickness control and doping parameters for dopant uniformity, resolving the contradiction between process integration and manufacturing precision.
Solution Approach 2:
The polysilicon layer is deposited to the pre-determined thickness before doping is introduced. This preliminary action of forming the complete layer first allows precise control over the final thickness, as the deposition process can be optimized independently without the complicating factor of simultaneous dopant introduction affecting the deposition rate and layer formation.
2Productivity
If in-situ doping is performed during polysilicon deposition, then no extra doping process is needed, but dopant uniformity and active dopant concentration become difficult to control
Solution Approach 1:
The manufacturing process is segmented into distinct deposition and doping phases, allowing each to be optimized independently. The deposition phase focuses on forming a uniform polysilicon layer, while the subsequent doping phase focuses on achieving uniform dopant distribution and precise dopant concentration control, thereby maintaining high productivity while improving dopant uniformity.
Solution Approach 2:
The process utilizes parameter changes by conducting doping at elevated temperatures (e.g., 900-1100°C) after deposition. This temperature parameter change enables better dopant diffusion and uniform distribution throughout the layer, achieving superior dopant uniformity and active dopant concentration control compared to low-temperature in-situ doping.
3Productivity
If higher deposition rates are pursued, then throughput increases, but control over layer thickness and dopant uniformity deteriorates
Solution Approach 1:
By separating deposition and doping into distinct processes, the invention allows the deposition stage to be optimized for high deposition rate without compromising thickness uniformity. The subsequent doping stage then ensures uniform dopant distribution throughout the rapidly deposited layer, maintaining manufacturing precision even at higher productivity levels.
Solution Approach 2:
The invention employs parameter changes by conducting the doping process at high temperatures (900-1100°C) after rapid deposition. This temperature parameter change enables effective dopant diffusion and uniform distribution even in layers deposited at high rates, thereby maintaining dopant uniformity and thickness control despite increased deposition speed.
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 the formation of thicker doped polysilicon layers with improved throughput, uniform dopant concentration, and higher doping concentrations, addressing the limitations of existing in-situ doping techniques while maintaining uniformity and reducing wafer non-uniformity.
Implementation Method 1
providing a silicon-containing precursor to the process chamber, thereby depositing on the plurality of substrates an undoped silicon layer
Implementation Method 2
performing a heat treatment process, thereby forming the doped polysilicon layer
Data Source
Figure 1~2b
Figure 3~4
AI summary
A method and a wafer processing furnace for forming a doped polysilicon layer on a plurality of substrates is provided. In a preferred embodiment, the method comprises providing a plurality of substrates to a process chamber. It also comprises executing a deposition cycle comprising providing a silicon-containing precursor to the process chamber thereby depositing, on the plurality of substrates, an undoped silicon layer until a pre-determined thickness is reached and providing the process chamber with a flow of a dopant precursor gas without providing the silicon-containing precursor to the process chamber. The method also comprises performing a heat treatment process, thereby forming the doped polysilicon layer.