Semiconductor Doping Process with Segmented Diffusion Phases
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Solution Overview
Problem
Current semiconductor doping processes cannot independently adjust dopant concentration near the surface and diffusion depth, requiring adjustments that alter both parameters simultaneously, limiting flexibility and efficiency.
Innovation Solution
A method involving a three-phase diffusion process: a first occupation phase for initial dopant deposition, a drive-in phase for diffusion, and a second occupation phase for simultaneous dopant redeposition, allowing separate control of surface concentration and depth through gas flow adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If process parameters (temperature, gas flows) are adjusted to change doping profile, then doping concentration and depth are modified, but both surface concentration and diffusion depth change simultaneously, preventing independent adjustment
Solution Approach 1:
The doping process is divided into three distinct phases: first occupation phase for initial dopant deposition, drive-in phase for diffusion without additional dopant, and second occupation phase for final dopant deposition. This segmentation allows independent control of surface concentration (via second occupation phase duration and gas flow) and diffusion depth (via drive-in phase temperature and duration), resolving the contradiction between adaptability and process complexity.
2Adaptability or versatility
If multiple process parameters are adjusted to achieve desired doping profile, then flexibility is improved, but process duration and complexity increase
Solution Approach 1:
The doping process uses periodic occupation phases separated by a drive-in phase. The first occupation phase deposits initial dopant, followed by drive-in diffusion, then the second occupation phase adds final dopant concentration. This periodic structure enables independent adjustment of surface concentration and diffusion depth while maintaining a consistent thermal budget, reducing total process duration compared to traditional multi-parameter adjustment methods.
3Ease of operation
If traditional single occupation phase is used, then process is simple, but surface concentration and diffusion depth cannot be independently adjusted
Solution Approach 1:
The process segments the occupation phase into two distinct occupation phases with a drive-in phase in between. The first occupation phase establishes initial dopant distribution, the drive-in phase controls diffusion depth, and the second occupation phase adjusts surface concentration. This segmentation maintains operational simplicity while enabling independent adjustment of doping parameters.
Solution Approach 2:
The first occupation phase performs preliminary dopant deposition before the drive-in phase. This preliminary action establishes a dopant source that will diffuse during the drive-in phase, while the second occupation phase performs final concentration adjustment after diffusion is complete, enabling independent control of depth and surface concentration.
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
Enables independent adjustment of surface dopant concentration and diffusion depth, improving process flexibility and reducing process duration while maintaining a consistent thermal budget, suitable for co-diffusion processes.
Implementation Method 1
in a drive-in phase at least one dopant diffuses into the semiconductor substrate
Implementation Method 2
in a first occupation phase at least one dopant source is deposited at least in regions on a surface of a semiconductor substrate
Data Source
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AI summary
The invention relates to a method for doping semiconductor substrates by means of a diffusion process, wherein in a first coating phase, at least one dopant source is deposited at least in some areas on a surface of a semiconductor substrate, then in a drive-in phase, at least one dopant diffuses into the semiconductor substrate, and in a second coating phase, the at least one dopant source is deposited again at least in some areas on the semiconductor substrate while at least one dopant simultaneously diffuses into the semiconductor substrate. In said method, the dopant concentration in the area near the surface can be set independently of the diffusion depth of the dopant. The invention further relates to semiconductor substrates doped in such a way.