Ti/Ni Multilayer Stressor for Thin Substrate Detachment
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Solution Overview
Problem
Existing methods for producing thin substrate layers from ingots are limited in achieving high stress induction and result in increased material consumption and production costs, particularly when using materials like GaAs or Ge, as the stress value decreases with increasing layer thickness and relaxation occurs within single-layer structures.
Innovation Solution
A method involving a stressor layer structure with alternating titanium and nickel layers, bonded to the ingot surface, is used to induce tensile stress, allowing for the detachment of thin substrate layers with high precision and reduced material consumption by exploiting the difference in thermal expansion coefficients between the ingot and the stressor layer, which can be removed after detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer stressor structure is used, then the device complexity is reduced, but the stress induction effectiveness decreases due to relaxation within the layer
Solution Approach 1:
The stressor layer is divided into multiple alternating layers of materials with different thermal expansion coefficients (e.g., Ti/Ni/Ti/Ni). This segmentation prevents stress relaxation that occurs in single-layer structures, as each interface between dissimilar materials maintains the tensile stress state. The segmented multilayer structure achieves higher and more stable stress induction for thin substrate layer detachment.
Solution Approach 2:
The invention uses composite multilayer structures combining materials with contrasting thermal expansion properties. The alternating layers of high-expansion and low-expansion materials create a composite system that generates and maintains tensile stress through differential thermal expansion, overcoming the limitations of homogeneous single-layer structures.
2Loss of substance
If the substrate layer thickness is reduced to save material costs, then the material consumption decreases, but the reliability of detachment becomes compromised
Solution Approach 1:
The invention changes the stress induction parameters by using multilayer stressor structures with optimized layer thicknesses and material compositions. This enables reliable detachment of extremely thin substrate layers (5-50 μm) by generating sufficient tensile stress that overcomes the reduced mechanical strength of thinner substrates, thereby maintaining detachment reliability while minimizing material usage.
3Stress or pressure
If a multilayer stressor structure is used, then the stress induction is enhanced, but the device complexity increases
Solution Approach 1:
The stressor layer is divided into multiple alternating layers of materials with different thermal expansion coefficients (e.g., Ti/Ni/Ti/Ni). This segmentation prevents stress relaxation that occurs in single-layer structures, as each interface between dissimilar materials maintains the tensile stress state. The segmented multilayer structure achieves higher and more stable stress induction for thin substrate layer detachment.
Solution Approach 2:
Different layers in the multilayer structure have locally optimized properties - alternating between high-expansion and low-expansion materials with specific thicknesses tailored to maximize stress induction at each interface. This local differentiation of material properties throughout the stack creates cumulative stress effects that enhance overall performance.
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 reliable and reproducible production of extremely thin substrate layers (5 μm to 50 μm) with reduced material usage and production costs, enhancing stress induction and minimizing the need for problematic materials like GaAs or Ge.
Implementation Method 1
The stressor layer structure and the ingot have different thermal expansion coefficients
Data Source
AI summary
A method for producing a thin substrate layer having a thickness of at most 100 μm by detaching a substrate layer from the ingot by producing a tensile stress induction on an ingot, and wherein the tensile stress induction is effected by a stressor layer structure integrally bonded to a first surface of the ingot. The stressor layer structure and the ingot have different thermal expansion coefficients, and the stressor layer structure is removed from the substrate layer after detachment of the substrate layer from the ingot. The stressor layer structure has at least one layer sequence with a first titanium-containing layer and a nickel-containing layer. The titanium-containing layer adjoins with a bottom side a first surface of the ingot and the nickel-containing layer adjoins with a bottom side a top side of the titanium-containing layer.