Plasma-Enhanced Phosphorus Diffusion in Semiconductor Manufacturing
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Solution Overview
Problem
Conventional ion injection methods for semiconductor devices face challenges in achieving shallow and uniform phosphorus atom diffusion, especially in three-dimensional device structures, and result in desorption of phosphorus atoms over time or during annealing.
Innovation Solution
A semiconductor device manufacturing method and apparatus that applies a resist to a silicon substrate, uses plasma to excite phosphorus-containing gas, and forms a diffusion layer with a temperature below the resist's deterioration point, followed by forming an oxide film to prevent desorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ion injection method is used to control injection amount and depth, then phosphorus atoms can be injected with controlled parameters, but the method is disadvantageous for achieving extremely shallow injection and uniform diffusion in three-dimensional structures
Solution Approach 1:
The patent replaces the mechanical ion injection method with a plasma-based diffusion method. Instead of using ion beams with acceleration voltage to control injection depth, the invention uses plasma to generate phosphorus atoms that diffuse into the silicon substrate through thermal and chemical processes, enabling uniform diffusion in three-dimensional structures without the anisotropy limitations of directional ion injection
Solution Approach 2:
The patent changes the fundamental parameter from ion beam acceleration voltage to plasma temperature and phosphorus atom concentration. By controlling plasma parameters (temperature, pressure, gas flow) rather than ion beam energy, the method achieves uniform phosphorus distribution in both vertical and lateral directions, suitable for three-dimensional device construction
2Manufacturing precision
If phosphorus atoms are diffused shallowly using plasma method, then uniform diffusion both vertically and laterally is achieved, but phosphorus atoms are desorbed with lapse of time or during annealing
Solution Approach 1:
The patent applies preliminary action by forming an oxide film immediately after phosphorus atom diffusion while the substrate is still hot. This oxide film is formed in-situ without cooling the substrate, ensuring that the phosphorus atoms are trapped before they can desorb. The preliminary formation of the oxide barrier prevents subsequent phosphorus loss during storage or annealing processes
Solution Approach 2:
The patent introduces an oxide film as an intermediary layer between the phosphorus atoms and the silicon substrate surface. This oxide film acts as a barrier that prevents phosphorus atoms from desorbing into the environment or diffusing back out during subsequent processing steps, thereby ensuring long-term retention of the phosphorus doping profile
3Manufacturing precision
If substrate temperature is raised to form diffusion layer, then phosphorus atoms diffuse into silicon substrate, but resist on substrate surface deteriorates or hardens
Solution Approach 1:
The patent changes the diffusion mechanism from thermal diffusion requiring high temperatures to plasma-enhanced diffusion that can occur at lower temperatures. By using plasma to generate reactive phosphorus atoms and provide energy for diffusion, the process can be conducted at temperatures below the resist deterioration point, eliminating the harmful thermal effect on the resist while still achieving effective phosphorus diffusion
Solution Approach 2:
The patent replaces thermal diffusion (heat-driven) with plasma-enhanced diffusion (chemically active species-driven). Instead of relying on high temperature to provide diffusion energy, the invention uses plasma-generated phosphorus atoms that are chemically reactive and can diffuse into the silicon substrate at lower temperatures, thereby protecting the resist from thermal damage
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 effectively prevents the desorption of phosphorus atoms from the silicon substrate, allows for uniform and shallow diffusion both vertically and laterally, and maintains the substrate temperature below the resist's deterioration point, enhancing processing efficiency and preventing resist hardening.
Implementation Method 1
a plasma generation unit that generates plasma to excite the gas supplied from the gas supply line
Implementation Method 2
a diffusion layer forming step of forming the diffusion layer, with a temperature of the silicon substrate maintained lower than a deterioration temperature of the resist
Data Source
AI summary
To provide a manufacturing method of a semiconductor device for forming a diffusion layer by diffusing phosphorus atoms on a surface of a silicon substrate on which resist is applied, including the step of forming a diffusion layer, with a temperature of the silicon substrate maintained lower than a deterioration temperature of the resist.