Heteroepitaxial Silicon Substrate Thick-Then-Thin Processing
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Solution Overview
Problem
Existing methods for producing heteroepitaxial substrates with thicker silicon single crystal substrates than the standard thickness face issues with warping and cracking, preventing their introduction into existing device processes due to dimensional mismatches, leading to increased costs for dedicated apparatuses.
Innovation Solution
A method involving producing a silicon single crystal substrate with a thickness exceeding the standard upper limit, growing a heteroepitaxial layer, and then thinning the substrate to meet the standard thickness, thereby suppressing warping and cracking, allowing integration into existing device processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the silicon single crystal substrate is increased to suppress warping and cracking during heteroepitaxial growth, then the structural integrity is improved, but the substrate cannot be introduced into existing device processes due to dimensional mismatches
Solution Approach 1:
The substrate processing is divided into distinct stages: initial growth on a thick substrate (greater than 775 μm) to ensure structural integrity during heteroepitaxial growth, followed by a subsequent thinning stage to reduce the substrate thickness to within standard specifications (≤775 μm). This segmentation allows each stage to optimize for its specific requirements without compromise.
Solution Approach 2:
The heteroepitaxial layer is grown on the silicon substrate before the substrate thickness is reduced to standard dimensions. This preliminary action ensures that the critical growth process occurs on a substrate with sufficient thickness to prevent warping and cracking, while the thickness reduction is performed as a subsequent step that does not compromise the already-formed heteroepitaxial structure.
2Reliability
If the thickness of the silicon single crystal substrate is made thicker than the standard, then warping and cracking are suppressed, but dedicated apparatuses are required which increases costs
Solution Approach 1:
The method enables a single substrate processing system to handle both thick substrates (for initial growth) and standard-thickness substrates (for subsequent processing) using existing equipment. The thick substrate is used temporarily during the growth phase and then thinned to standard dimensions, allowing the same apparatus to process substrates through multiple stages without requiring dedicated equipment for each stage.
3Strength
If the thickness of the silicon single crystal substrate is increased beyond the standard upper limit, then strength is improved, but the substrate dimension deviates from SEMI standards
Solution Approach 1:
The manufacturing process is segmented into two distinct phases with different thickness requirements: Phase 1 involves heteroepitaxial growth on a thick substrate (>775 μm) where strength is the priority, and Phase 2 involves thinning the substrate to meet standard specifications (≤775 μm) where dimensional conformity is the priority. This segmentation resolves the contradiction by allowing each phase to optimize for its specific requirement.
Solution Approach 2:
The heteroepitaxial layer formation is performed as a preliminary action before the substrate thickness is adjusted to meet standard specifications. This ensures that the critical growth process benefits from the enhanced strength of the thick substrate, while the final dimensional conformity is achieved in a subsequent step that does not compromise the growth quality.
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 heteroepitaxial substrates that can withstand thicker silicon single crystal substrates without cracking, facilitating their introduction into standard semiconductor processes while maintaining structural integrity and process compatibility.
Implementation Method 1
epitaxially growing a heteroepitaxial layer on the silicon single crystal substrate
Data Source
Figure 1~2
AI summary
The present invention is a method for producing a heteroepitaxial substrate, the method including the steps of producing a substrate in which a silicon single crystal substrate is produced under thickness conditions of a thickness of 2 mm or less, the thickness exceeds an upper limit of a thickness standard defined corresponding to a diameter of the silicon single crystal substrate, epitaxially growing a heteroepitaxial layer on the silicon single crystal substrate obtained in the step of producing the substrate to obtain an epitaxial substrate, and thinning the silicon single crystal substrate so as to fall within the thickness standard by grinding a surface of the silicon single crystal substrate opposite to a surface on which the heteroepitaxial layer is formed after the step of epitaxially growing. This provides the method for producing a heteroepitaxial substrate that can be introduced in an existing device process, even when the thickness of the silicon single crystal substrate is thicker than the standard to form the heteroepitaxial layer.