Linear Electron Beam Crystallization of Amorphous Silicon Thin Films
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Solution Overview
Problem
Current methods for crystallizing polycrystalline silicon thin films on amorphous glass substrates face challenges such as high temperature requirements, metal residue issues, weak adhesiveness, and non-uniform energy distribution, limiting the production of high-quality solar cells.
Innovation Solution
A method involving the use of a linear electron beam to crystallize large-area amorphous silicon thin films on low-cost substrates, such as glass or metal foils, using plasma enhanced chemical vapor deposition and physical vapor deposition techniques, achieving high crystallization fractions and large grain sizes with low-temperature processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat method is used for crystallization, then crystallization can be achieved, but temperature exceeds glass substrate melting point making it impossible
Solution Approach 1:
The patent replaces thermal field (heat method) with electron beam field to achieve crystallization. The electron beam provides localized energy deposition that crystallizes amorphous silicon at lower temperatures without melting the glass substrate, thus resolving the temperature-substrate compatibility contradiction.
Solution Approach 2:
The patent changes the energy delivery parameter from thermal (heat) to kinetic (electron beam). By controlling electron beam parameters such as current density, scanning speed, and acceleration voltage, crystallization is achieved at temperatures below the glass substrate melting point.
2Manufacturing precision
If laser beam crystallization is used, then high-quality crystallization is achieved, but shot mark phenomenon occurs due to non-uniform energy distribution
Solution Approach 1:
The patent replaces laser beam (optical field) with electron beam (particle field) for crystallization. The electron beam can be scanned in a linear fashion with more uniform energy distribution, avoiding the shot mark phenomenon associated with laser spot scanning while maintaining crystallization quality.
Solution Approach 2:
The patent employs linear scanning motion of the electron beam across the substrate, creating continuous and uniform energy distribution. This dynamic scanning approach eliminates the stationary spot exposure that causes shot marks in laser crystallization, achieving uniform crystallization across large areas.
3Temperature
If metal induced crystallization is used, then crystallization below glass melting point is achieved, but metal residues reduce product quality
Solution Approach 1:
The patent extracts and eliminates the metal catalyst component from the crystallization process. By using direct electron beam irradiation, crystallization is achieved without any metal intermediaries, thus preventing metal residue contamination while maintaining low-temperature processing capability.
Solution Approach 2:
The patent uses electron beam as an energy mediator instead of metal catalysts. The electron beam directly transfers energy to amorphous silicon atoms to induce crystallization without requiring metal intermediaries, thereby avoiding metal residue issues while achieving crystallization below glass melting point.
4Area of stationary object
If large-area amorphous silicon thin film is crystallized, then large-area solar cell is produced, but crystallization time becomes excessively long
Solution Approach 1:
The patent employs continuous linear scanning of the electron beam across the large-area substrate, maintaining continuous energy deposition and crystallization action. This continuous process avoids interruptions and achieves complete crystallization of large areas more efficiently than step-by-step or spot-based methods.
Solution Approach 2:
The patent uses dynamic linear scanning motion of the electron beam to cover large areas efficiently. By optimizing scanning speed and beam current, the system achieves uniform crystallization across large substrates in reduced time compared to static or slow scanning methods.
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 production of high-quality polycrystalline silicon thin film solar cells with high crystallization fractions and large grain sizes in a short time, using low-cost substrates and minimizing manufacturing costs while avoiding degradation phenomena.
Implementation Method 1
crystallizing a large-area amorphous silicon thin film using a linear electron beam
Implementation Method 2
forming an absorption layer by crystallizing the type 1 amorphous silicon layer and the type 1+ amorphous silicon layer by irradiating the type 1 amorphous silicon layer with a linear electron beam
Implementation Method 3
depositing a type 1 amorphous silicon layer by a plasma enhanced chemical vapor deposition method
Implementation Method 4
depositing a type 1 amorphous silicon layer by a physical vapor deposition method
Data Source
AI summary
One embodiment of the present invention relates to a method of manufacturing polycrystalline silicon thin-film solar cell by a method of crystallizing a large-area amorphous silicon thin film using a linear electron beam, and the technical problem to be solved is to crystallize an amorphous silicon thin film, which is formed on a low-priced substrate, by means of an electron beam so as for same to easily be of high quality by having high crystallization yield and to be processed at a low temperature. To this end, one embodiment of the present invention provides a method of manufacturing polycrystalline silicon thin-film solar cell by means of a method for crystallizing a large-area amorphous silicon thin film using a linear electron beam, the method comprising: a substrate preparation step for preparing a substrate; a type 1+ amorphous silicon layer deposition step for forming a type 1+ amorphous silicon layer on the substrate; a type 1 amorphous silicon layer deposition step for forming a type 1 amorphous silicon layer on the type 1+ amorphous silicon layer; an absorption layer formation step for forming an absorption layer by radiating a linear electron beam to the type 1 amorphous silicon layer and thus crystallizing the type 1 amorphous layer and the type 1+ amorphous silicon layer; a type 2 amorphous silicon layer deposition step for forming a type 2 amorphous silicon layer on the absorption layer; and an emitter layer formation step for forming an emitter layer by radiating a linear electron beam to the type 2 amorphous silicon layer and thus crystallizing the type 2 amorphous silicon layer, wherein the linear electron beam is radiated from above type 1 and type 2 amorphous silicon layers in a linear scanning manner in which to reciprocate in a predetermined area.