Semiconductor Device Laser Annealing Adhesion
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Solution Overview
Problem
The existing methods for manufacturing semiconductor devices, particularly thin film transistors (TFTs) using amorphous and microcrystalline silicon films, face issues such as threshold voltage shifts, film peeling, and poor adhesion between semiconductor layers, leading to decreased yield and production efficiency due to the formation of native oxide films and contamination during the microcrystalline semiconductor film processing.
Innovation Solution
A method involving the formation of a gate electrode and insulating film, followed by laser annealing of an amorphous semiconductor film to convert it into a crystalline film, and subsequent hydrofluoric acid processing to improve adhesion, where the amorphous semiconductor film is formed to cover the crystalline film with its pattern ends outside the crystalline film's pattern, ensuring contact with the insulating film near the edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an amorphous semiconductor film is formed and then microcrystallized by laser beam irradiation, then the defect level density is reduced and threshold voltage shift is minimized, but a native oxide film is formed on the surface and the film adheres poorly to subsequent layers
Solution Approach 1:
The patent applies hydrofluoric acid processing to the microcrystalline semiconductor film surface before forming the next semiconductor layer. This preliminary action removes the native oxide film that forms during laser annealing, preventing adhesion problems and ensuring good interface quality between layers while maintaining the low defect density achieved through microcrystallization.
2Ease of manufacture
If plasma CVD method is used to form microcrystalline semiconductor film, then the film can be deposited, but an incubation layer of amorphous semiconductor forms initially which contacts the gate insulating film causing electron trapping and threshold voltage shift
Solution Approach 1:
The patent performs laser beam irradiation to microcrystallize the semiconductor film while it is still in the amorphous state, before subsequent processing steps. This preliminary microcrystallization ensures that the film contacting the gate insulating film has low defect density from the beginning, preventing electron trapping and threshold voltage shift that would occur if an amorphous incubation layer remained.
3Reliability
If multiple semiconductor layers are formed with precise pattern alignment, then device performance is improved, but misalignment between layers causes step cutting and reduces yield
Solution Approach 1:
The patent forms the microcrystalline semiconductor film with a pattern that extends beyond the final device boundaries, then performs hydrofluoric acid processing to remove oxide and define the exact pattern boundaries. This preliminary over-extension followed by precise chemical processing ensures perfect alignment between layers and eliminates step cutting, improving both device performance and yield.
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 enhances the adhesion between the amorphous and crystalline semiconductor films, reduces film peeling and step cutting, and maintains high TFT performance and reliability, thereby improving the yield and efficiency of semiconductor device production.
Implementation Method 1
irradiated with a laser beam, so as to microcrystallize the semiconductor film
Implementation Method 2
the amorphous semiconductor film is irradiated with a laser beam, so as to microcrystallize the semiconductor film
Implementation Method 3
performing hydrofluoric acid processing on the crystalline semiconductor film
Data Source
AI summary
According to a method of manufacturing a semiconductor device of the present invention, a gate electrode is formed above a substrate, and a insulating film is formed above the gate electrode. Then, an amorphous semiconductor film is formed above the insulating film, laser annealing is performed on the amorphous semiconductor film, and the amorphous semiconductor film is changed to a crystalline semiconductor film. After that, hydrofluoric acid processing is performed on the crystalline semiconductor film, and an amorphous semiconductor film is formed above the crystalline semiconductor film where the hydrofluoric acid processing is performed so that pattern ends of the amorphous semiconductor film are arranged outside pattern ends of the crystalline semiconductor film and the amorphous semiconductor film contacts with the insulating film near the pattern ends.