Bonded Wafer Bonding Layer Thickness for Warpage Control
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Solution Overview
Problem
The existing techniques for bonding a semiconductor epitaxial substrate to a support substrate using a thermosetting bonding material face challenges due to warpage issues, leading to uneven film thickness distribution and mechanical strength concerns, especially when thermal expansion coefficients differ between materials.
Innovation Solution
A bonded wafer is created using a thermosetting bonding material with an average thickness of 0.01 μm to 0.6 μm, comprising materials like epoxy resin, benzocyclobutene, SOG, PI, or fluororesin, which is applied in a softened state to minimize film thickness distribution and enhance mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bonding layer thickness is increased to suppress multiple reflections and enhance mechanical strength, then optical characteristics and mechanical strength are improved, but film thickness distribution becomes larger due to warpage of the semiconductor epitaxial substrate
Solution Approach 1:
The patent applies pressure to the semiconductor epitaxial substrate before bonding to correct its warpage. By changing the physical state of the substrate through mechanical pressure, the warpage is reduced, which in turn minimizes film thickness distribution when the bonding material is applied. This allows for better control of bonding layer thickness while maintaining mechanical strength.
2Reliability
If temperature is raised to cure the thermosetting bonding material, then bonding is achieved, but warpage of the semiconductor epitaxial substrate changes due to different thermal expansion coefficients, causing film thickness distribution
Solution Approach 1:
The patent applies pressure to correct warpage of the semiconductor epitaxial substrate before the bonding material is applied and before thermal curing occurs. By performing this warpage correction in advance, the substrate is pre-flattened, so that subsequent temperature changes during curing do not cause significant film thickness distribution. This preliminary action prevents the problem rather than correcting it afterward.
3Shape
If pressure is applied to correct warpage of the semiconductor epitaxial substrate, then warpage is reduced, but film thickness distribution of the bonding material occurs along the warped shape before compression bonding
Solution Approach 1:
The patent applies pressure to correct warpage of the semiconductor epitaxial substrate before the bonding material is applied. By performing this warpage correction in advance, the substrate is pre-flattened, so that when the bonding material is subsequently applied, there is minimal warpage to cause film thickness distribution. The timing of the pressure application is critical - it must occur before bonding material deposition.
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 significantly reduces film thickness variations and maintains mechanical strength, preventing peeling and improving optical characteristics by maintaining uniformity in light distribution and mechanical integrity.
Implementation Method 1
The bonding material has a thermosetting property, in other words, it is necessary to raise the temperature above room temperature in order to cure it
Implementation Method 2
A semiconductor epitaxial substrate is a laminate of materials different from the starting substrate, and the thermal expansion coefficient differs for each material. Therefore, raising the temperature is essentially synonymous with changing the warpage of the semiconductor epitaxial substrate
Data Source
AI summary
A bonded wafer, wherein an epitaxial wafer having a heterojunction structure, in which a material with a different thermal expansion coefficient is epitaxially laminated on a growth substrate, and a support substrate are bonded via a bonding material, wherein the bonding material has an average thickness of 0.01 μm or more and 0.6 μm or less. As a result, provided is a bonded wafer and a method for producing the same that improves the film thickness distribution of the bonding material caused by the warpage of the semiconductor epitaxial substrate and the warpage that changes with thermal changes when the warped semiconductor epitaxial substrate and the support substrate are bonded together using the bonding material.