Thin SOI Substrate Structure for Heat Dissipation Without Carrier Wafers
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Solution Overview
Problem
Existing silicon-on-insulator (SOI) substrates face challenges in achieving a thin silicon layer thickness and efficient heat dissipation while maintaining the integrity of the insulative layer and semiconductor devices, often requiring sacrificial carrier substrates and hydrogen implantation.
Innovation Solution
The implementation of an SOI die with a silicon layer less than 35 micrometers thick, coupled with a thermally conductive insulative layer directly to one side, and a conductive layer, formed through backgrinding and deposition methods like co-evaporation or co-sputtering without hydrogen implantation, allowing for stress relief etching and heat dissipation without a sacrificial carrier substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the silicon layer thickness is reduced to improve device performance, then the substrate thickness decreases, but the mechanical strength and integrity of the substrate deteriorate
Solution Approach 1:
The patent applies composite materials by combining a thin silicon layer with a thick insulative layer (such as silicon dioxide or silicon nitride) to create an SOI substrate. The insulative layer serves as a mechanical support that compensates for the reduced strength of the thin silicon layer, enabling the substrate to maintain structural integrity at reduced thicknesses of 35 micrometers or less while improving device performance.
2Temperature
If a thermally conductive insulative layer is applied to improve heat dissipation, then heat management improves, but the complexity of the manufacturing process increases
Solution Approach 1:
The insulative layer in the SOI substrate serves multiple functions simultaneously: it provides electrical insulation between the silicon layer and underlying structures, acts as a mechanical support for thin silicon layers, and functions as a thermal management pathway when made from thermally conductive materials. This multi-functionality reduces the need for separate heat dissipation structures, thereby limiting the increase in manufacturing complexity while improving heat dissipation.
Solution Approach 2:
The patent utilizes parameter changes by selecting insulative layer materials with specific thermal conductivity properties. By changing the material parameters of the insulative layer (such as using silicon nitride or doped silicon dioxide with enhanced thermal conductivity), the substrate achieves improved heat dissipation capabilities while maintaining the same basic structural configuration, thus avoiding significant increases in manufacturing process complexity.
3Reliability
If hydrogen implantation is used to improve substrate properties, then the substrate integrity improves, but the manufacturing process complexity and time increase
Solution Approach 1:
The patent extracts or eliminates the hydrogen implantation step from the manufacturing process by relying on the inherent properties of the insulative layer and the backgrinding process to achieve the desired substrate integrity. The backgrinding process itself, combined with the stress relief etching and proper material selection, provides sufficient substrate preparation without requiring additional hydrogen implantation steps, thereby reducing manufacturing cycle time while maintaining substrate integrity.
4Strength
If sacrificial carrier substrates are used to maintain substrate integrity, then the substrate strength improves, but the manufacturing process complexity and material usage increase
Solution Approach 1:
The insulative layer acts as an intermediary structure that provides mechanical support to the thin silicon layer, replacing the need for sacrificial carrier substrates. During the backgrinding process, the insulative layer (when deposited on the backside) serves as a protective and supporting medium that maintains substrate strength throughout manufacturing. This eliminates the need for additional sacrificial materials that would require subsequent removal steps, thereby reducing material usage and process complexity.
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 production of SOI dies with improved heat management and reduced substrate thickness, enhancing semiconductor device performance and efficiency without the need for hydrogen implantation or sacrificial carriers.
Implementation Method 1
The insulative layer may include a thermally conductive material
Implementation Method 2
The insulative layer may be deposited using either co-evaporation or co-sputtering
Implementation Method 3
The insulative layer may be deposited using either co-evaporation or co-sputtering
Data Source
AI summary
Implementations of a silicon-on-insulator (SOI) die may include a silicon layer including a first side and a second side, and an insulative layer coupled directly to the second side of the silicon layer. The insulative layer may not be coupled to any other silicon layer.