Thin SOI Die Structure Without Hydrogen Implantation
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Solution Overview
Problem
Existing silicon-on-insulator (SOI) substrate technologies face challenges in achieving a thin silicon layer with effective stress management and heat dissipation, while avoiding the use of hydrogen implantation and sacrificial carrier substrates.
Innovation Solution
The implementation of a silicon-on-insulator (SOI) die with a silicon layer less than 35 micrometers thick, coupled with an insulative layer that is directly attached to the second side of the silicon layer, and optionally includes a conductive layer for enhanced adhesion and electrical properties. The method involves backgrinding, depositing the insulative layer using co-evaporation or co-sputtering, and singulating the substrate without using a sacrificial carrier substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the silicon layer thickness is reduced to less than 35 micrometers, then the capacitance is reduced and device performance is improved, but the mechanical strength and stress management become problematic
Solution Approach 1:
The patent creates a composite structure by depositing an insulative layer (such as silicon dioxide or silicon nitride) directly onto the thinned silicon substrate. This composite construction provides both electrical insulation and mechanical support, allowing the silicon layer to be reduced to less than 35 micrometers while maintaining structural integrity through the combined properties of the silicon-insulator composite system.
2Stress or pressure
If hydrogen implantation is used to manage stress in thin silicon layers, then stress management is improved, but device reliability deteriorates due to hydrogen-related defects
Solution Approach 1:
The patent extracts and eliminates the hydrogen implantation step from the manufacturing process. Instead of using hydrogen to manage stress, the invention relies on the intrinsic stress properties of the insulative layer and the natural stress distribution in the thinned silicon substrate, thereby avoiding hydrogen-related defects while maintaining stress management through alternative physical mechanisms.
Solution Approach 2:
The thinned silicon substrate manages its own stress through the mechanical support provided by the insulative layer and the backgrinding process, without requiring external hydrogen implantation. The structure serves itself by utilizing the physical properties of the materials and the geometric configuration to maintain stress balance naturally.
3Ease of manufacture
If sacrificial carrier substrates are used during manufacturing, then the manufacturing process becomes easier, but the production complexity and cost increase
Solution Approach 1:
The patent removes the sacrificial carrier substrate step from the manufacturing process. The silicon substrate is thinned and processed directly without being mounted on a carrier, eliminating the additional steps of carrier attachment, processing, and subsequent carrier removal. This direct processing approach reduces process complexity while maintaining manufacturing feasibility through precise control of the backgrinding and insulative layer deposition steps.
4Temperature
If the silicon substrate is thinned to less than 35 micrometers, then the heat dissipation efficiency is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent replaces traditional mechanical thinning methods with a controlled backgrinding process followed by insulative layer deposition. The backgrinding step removes material from the rear surface of the substrate in a controlled manner, and the subsequent deposition of the insulative layer provides a stable termination point for the thinning process, enabling precise thickness control at less than 35 micrometers while maintaining good surface quality and thermal properties.
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 allows for the production of SOI dies with improved stress management and reduced thickness, enabling efficient heat dissipation and minimizing the need for hydrogen implantation and sacrificial carrier substrates, thus enhancing the overall performance and manufacturing efficiency of SOI substrates.
Implementation Method 1
depositing an insulative layer onto the second side of the silicon substrate after backgrinding
Implementation Method 2
depositing an insulative layer onto the second side of the silicon substrate after backgrinding
Implementation Method 3
dissipating heat through a heat dissipation device during deposition of the insulative layer
Implementation Method 4
forming a ring around the perimeter of a second side of a silicon substrate through backgrinding the second side of the substrate to a desired substrate thickness
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.