Crystalline Silicon Layer Formation Without ASIC Thermal Damage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing crystalline silicon layers on substrates with integrated electronic components, such as ASICs, face challenges in achieving high surface quality without damaging the components and are limited by high thermal stress, making monolithic integration of MEMS sensors impossible.
Innovation Solution
A method involving the deposition of an amorphous silicon layer on a substrate, followed by laser-induced solid-state crystallization below the melting point, which incorporates dopants to enhance conductivity and uses controlled laser parameters to minimize thermal stress and maintain component integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high process temperatures (>600°C) are used to fabricate crystalline silicon layers, then the material properties meet the requirements for MEMS sensor functionality, but the thermal stress limit of the existing circuits in the substrate is exceeded, causing irreversible changes in the electronic properties of the IC
Solution Approach 1:
The patent applies parameter changes by reducing the process temperature from >600°C to below 450°C, and by changing the crystallization method from thermal to laser-induced solid-state crystallization. This allows obtaining crystalline silicon layers with suitable properties without exceeding the thermal stress limit of the integrated circuits.
Solution Approach 2:
The patent replaces the conventional thermal crystallization process with laser-induced solid-state crystallization. Instead of using high-temperature thermal fields, a laser beam is used to provide localized energy for crystallization, thereby avoiding the thermal stress that would damage the electronic components.
2Temperature
If alternative material systems (metals, metal alloys, conductive metal oxides) are used to replace crystalline silicon, then deposition temperatures can be kept below 450°C, but the discrepancy in coefficients of thermal expansion between the alternative layer materials and crystalline silicon substrate leads to thermally induced stresses that significantly alter mechanical properties and impair sensor performance
Solution Approach 1:
The patent uses homogeneity by selecting silicon as the layer material, which has the same chemical composition and nearly identical thermomechanical behavior to the crystalline silicon substrate. This eliminates the thermal expansion coefficient discrepancy that would otherwise cause thermally induced stresses and mechanical property changes.
3Temperature
If excimer laser radiation is used to crystallize amorphous silicon layers, then crystallization can be achieved at lower temperatures, but the technique is not suitable for greater layer thicknesses and results in insufficient surface quality of the crystallized layer
Solution Approach 1:
The patent applies parameter changes by optimizing the laser parameters (wavelength, power, scanning speed) and process conditions to achieve solid-state crystallization with high surface quality. By carefully controlling these parameters, the method overcomes the limitations of previous laser crystallization techniques and enables processing of thicker layers while maintaining excellent surface finish.
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
Enables the production of high-quality crystalline silicon layers suitable for monolithically integrated MEMS sensors, reducing manufacturing complexity and enhancing sensor sensitivity by minimizing parasitic effects, while avoiding surface changes and thermal damage.
Implementation Method 1
the amorphous silicon layer crystallizes through solid-state crystallization, i.e., it is not melted
Implementation Method 2
crystallized by momentary melting using excimer laser radiation
Implementation Method 3
the layer is heated only to below its melting point and held at the appropriately elevated temperature for the time required for crystallization
Data Source
Figure 1a~1d
Figure 1e~1f
AI summary
The invention relates to a method for producing a crystalline silicon layer (8) on a substrate (1) having integrated electronic components, in which method an amorphous silicon layer (6) is first deposited on the substrate (1) and then crystallised on the substrate (1) in at least one or more regions by means of irradiation with laser radiation. According to the invention, the irradiation parameters of the irradiation with laser radiation are selected such that the amorphous silicon layer (6) crystallises by means of solid phase crystallisation. This allows e.g. MEMS structures consisting of crystalline silicon to be produced on an ASIC without the risk of temperature damage to the ASIC.