Pulse Train Annealing for Amorphous Silicon Recrystallization
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Solution Overview
Problem
The semiconductor industry faces challenges in forming high-quality single crystal layers over substrates due to epitaxial growth techniques that result in crystalline defects and slow growth rates, which affect memory capacity, switching speeds, and feature sizes in integrated circuits.
Innovation Solution
A method of solid phase recrystallization using sequential pulses of electromagnetic energy to convert amorphous layers into crystalline layers with the same grain structure and crystal orientation as a seed region, involving the deposition of insulation layers, seed regions, and targeted energy delivery to promote epitaxial growth and reduce defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If epitaxial growth technique is used to form single crystal layer, then crystal quality is improved, but growth rate is slow and throughput is reduced
Solution Approach 1:
The patent employs solid-phase recrystallization by heating the amorphous silicon layer to a temperature between 400°C and 800°C, inducing a phase transition from amorphous to crystalline state. This process uses the seed region's crystal structure to template the recrystallization, achieving high-quality single crystal formation without the slow growth rates of traditional epitaxial methods.
Solution Approach 2:
The patent pre-forms a crystalline seed region in the insulation layer before depositing the amorphous silicon layer. This preliminary crystalline structure serves as a template that guides the subsequent recrystallization process, enabling rapid formation of high-quality single crystal layers while maintaining crystal orientation and grain structure.
2Manufacturing precision
If epitaxial growth technique is used to form single crystal layer, then crystal quality is improved, but crystalline defects increase
Solution Approach 1:
The patent utilizes the seed region's crystal structure to self-template the recrystallization process. The amorphous silicon layer automatically aligns and recrystallizes according to the underlying seed region's grain structure and crystal orientation, eliminating the need for external alignment processes and reducing misalignment defects.
Solution Approach 2:
By controlling the phase transition from amorphous to crystalline state through precise temperature management (400°C-800°C), the patent enables the material to naturally reorganize into a defect-free crystal structure guided by the seed region, avoiding the crystalline defects that occur in conventional epitaxial growth.
3Manufacturing precision
If traditional thermal annealing is used for recrystallization, then crystal formation is achieved, but processing time is long and throughput is low
Solution Approach 1:
The patent employs a pulsed laser annealing process where laser energy is delivered in periodic pulses rather than continuous heating. This periodic energy input enables rapid thermal cycling that accelerates the recrystallization process significantly compared to traditional continuous thermal annealing, reducing processing time while maintaining crystal quality.
Solution Approach 2:
The patent replaces traditional thermal conduction-based annealing with direct laser heating. The laser energy is absorbed by the amorphous silicon layer and converted to heat locally, enabling rapid and precise temperature control that accelerates recrystallization without the thermal mass limitations of furnace-based systems.
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 quality of single crystal layers, reduces defects, and increases throughput by efficiently recrystallizing amorphous layers, addressing the limitations of existing epitaxial growth methods.
Implementation Method 1
directing a plurality of pulses of electromagnetic energy toward a surface of the seed region upon which the layer of first material is deposited for a period of time that is sufficient to recrystallize and convert the layer of first material
Implementation Method 2
solid phase recrystallization of thin film using electromagnetic energy in a series of sequential pulses of energy
Data Source
AI summary
Embodiments of the present invention provide methods of solid phase recrystallization of thin film using a plurality of pulses of electromagnetic energy. In one embodiment, the methods of the present invention may be used to anneal an entire substrate surface or selected regions of a surface of a substrate by delivering a plurality of pluses of energy to a crystalline seed region or layer upon which an amorphous layer is deposited to recrystallize the amorphous layer so that it has the same grain structure and crystal orientation as that of the underlying crystalline seed region or layer.