Polycrystalline Silicon Film Formation With Uniform Nickel Diffusion
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Solution Overview
Problem
Existing film forming methods face challenges in reducing agglomeration of nickel silicide and achieving uniform nickel distribution in the surface layer of polycrystalline silicon films, leading to surface roughness and difficulty in removing nickel residues.
Innovation Solution
A method involving the diffusion of nickel into an amorphous silicon film using a nickel source gas followed by metal-induced lateral crystallization, which reduces nickel silicide agglomeration and allows for the formation of polycrystalline silicon films with large grain size and small surface roughness, and facilitates easy removal of nickel residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nickel particles are adsorbed on the surface of amorphous silicon film and annealing is performed, then polycrystalline silicon film is formed, but nickel silicide agglomeration occurs and surface roughness increases
Solution Approach 1:
The patent applies preliminary action by diffusing nickel atoms into the amorphous silicon film before crystallization occurs. This pre-diffusion step ensures uniform nickel distribution throughout the film thickness, preventing subsequent agglomeration during the annealing process that forms the polycrystalline silicon film. The nickel is introduced in atomic form and distributed uniformly before the structural transformation happens.
Solution Approach 2:
The patent changes the physical and chemical parameters of nickel introduction by using nickel source gas instead of particle adsorption. This transforms the nickel delivery mechanism from surface-level particle deposition to volumetric atomic diffusion, fundamentally changing how nickel is distributed in the silicon film and preventing the agglomeration that leads to surface roughness.
2Reliability
If nickel particles are adsorbed on the surface, then crystallization can occur, but uniform nickel distribution in the surface layer is difficult to achieve
Solution Approach 1:
The patent replaces the mechanical particle adsorption system with a chemical vapor diffusion system. Instead of physically depositing nickel particles onto the surface, the invention uses nickel source gas that diffuses nickel atoms into the amorphous silicon film, achieving uniform distribution through atomic diffusion rather than mechanical deposition.
Solution Approach 2:
The invention changes the state of nickel from particulate to atomic form, and changes the delivery method from surface adsorption to volumetric diffusion. This parameter change enables uniform nickel distribution throughout the film thickness, as atoms diffuse evenly throughout the amorphous silicon matrix before crystallization locks them in place.
3Reliability
If conventional annealing is used to form polycrystalline silicon, then crystallization occurs, but nickel residues are difficult to remove
Solution Approach 1:
The patent applies preliminary action by uniformly distributing nickel atoms throughout the amorphous silicon film before crystallization. This pre-distribution prevents nickel from concentrating in removable surface residues, as the nickel is already integrated uniformly into the crystal structure during the metallurgical phase separation process.
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
The method effectively reduces nickel silicide agglomeration, achieves uniform nickel distribution, and results in polycrystalline silicon films with improved surface quality and reduced nickel residues, enhancing the efficiency of film formation.
Implementation Method 1
diffusing nickel into the amorphous silicon film by supplying a nickel source gas to the amorphous silicon film
Implementation Method 2
forming a polycrystalline silicon film by heating the amorphous silicon film, and crystallizing the amorphous silicon film by metal-induced lateral crystallization using the nickel diffused in the amorphous silicon film as a nucleus
Implementation Method 3
forming a polycrystalline silicon film by heating the amorphous silicon film
Data Source
AI summary
A film forming method includes preparing a substrate having an amorphous silicon film on a surface thereof, diffusing nickel into the amorphous silicon film by supplying a nickel source gas to the amorphous silicon film, and forming a polycrystalline silicon film by heating the amorphous silicon film, and crystallizing the amorphous silicon film by metal-induced lateral crystallization using the nickel diffused in the amorphous silicon film as a nucleus.