Selective Laser Crystallization for Glass Substrates
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Solution Overview
Problem
The challenge in the crystallization process for active matrix displays is the susceptibility of glass substrates to thermal deformation due to their low thermal resistance, which affects the productivity and efficiency of forming high-quality polycrystalline semiconductor films for thin-film transistors.
Innovation Solution
A selective crystallization method and laser crystallization apparatus that alternately arrange crystallization regions on multiple substrates, using a laser beam split into sub-beams to simultaneously crystallize these regions, thereby improving the crystallization process efficiency and reducing thermal stress on the substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal annealing using furnace annealing or rapid thermal annealing is used for crystallization, then the amorphous semiconductor film can be crystallized to form polycrystalline semiconductor film, but the glass substrate is susceptible to thermal deformation due to its low thermal resistance
Solution Approach 1:
The patent divides the substrate processing into multiple separate substrates (first substrate and second substrate) with alternately arranged crystallization regions. By processing these substrates alternately with the laser beam, the thermal load on any single substrate is reduced, preventing thermal deformation while still achieving complete crystallization of all regions.
Solution Approach 2:
The patent employs periodic action by alternately irradiating the first and second substrates with the laser beam in a repeating cycle. This periodic processing allows each substrate to be crystallized while having sufficient time to cool down between irradiations, preventing thermal deformation and enabling complete crystallization of all regions.
2Object-affected harmful factors
If a single substrate is crystallized at a time, then thermal deformation is minimized, but the productivity of the crystallization process is reduced
Solution Approach 1:
The patent segments the crystallization process into multiple substrates processed in parallel. By placing multiple substrates with alternately arranged crystallization regions in the processing system, the overall crystallization throughput is increased while each individual substrate receives controlled thermal exposure to prevent deformation.
Solution Approach 2:
The periodic alternation between processing different substrates allows the system to maintain high productivity by keeping multiple substrates in the processing pipeline simultaneously, while each substrate is treated in a controlled manner to prevent thermal damage.
3Productivity
If the laser beam irradiates all crystallization regions simultaneously, then productivity is improved, but thermal stress on the substrates increases causing deformation
Solution Approach 1:
The patent segments the laser irradiation process by spatially separating the crystallization regions onto multiple substrates. The laser beam processes these substrates in an alternating sequence rather than simultaneously, which distributes the thermal stress over time and prevents excessive stress concentration on any single substrate while maintaining high overall productivity.
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 productivity of the crystallization process by allowing for simultaneous and uniform crystallization of multiple substrates, improving device mobility and operating characteristics while minimizing thermal deformation of glass substrates.
Implementation Method 1
crystallizing the alternately arranged crystallization regions with a laser beam
Implementation Method 2
rapid thermal annealing
Data Source
AI summary
A selective crystallization method includes placing a first substrate including first crystallization regions on a second substrate including second crystallization regions such that the first crystallization regions and the second crystallization regions are arranged alternately, and crystallizing the alternately-arranged first crystallization regions and the second crystallization regions with a laser beam. A laser crystallization apparatus can be used in the selective crystallization method.