SOI Device Layer Transfer via Segmented Handle Wafer
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Solution Overview
Problem
There is a need for improved assemblies and methods to transfer the device layer of a semiconductor-on-insulator (SOI) substrate from the handle wafer to a replacement substrate, particularly to accommodate thinner packages and high-density chip stacking, while maintaining mechanical support and preserving the integrity of device structures during thinning and additional operations.
Innovation Solution
A method involving forming a device structure in a handle wafer, removing a section of the handle wafer to expose a buried dielectric layer, and attaching a permanent substrate with a cavity to receive the handle wafer section, allowing for the transfer of the device layer and preserving the integrity of deep trench capacitors, enabling the integration of SOI CMOS devices with engineered properties on a permanent substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the handle wafer is completely removed to enable thinner packages and high-density stacking, then package thickness is reduced, but mechanical support during thinning and additional operations is compromised
Solution Approach 1:
The handle wafer is segmented into two parts: a first section that is completely removed to enable thinning and high-density stacking, and a second section that is preserved to provide mechanical support during processing. This segmentation allows the package to achieve reduced thickness while maintaining structural integrity during fabrication.
Solution Approach 2:
The second section of the handle wafer is preserved in advance before thinning operations begin. This preliminary preservation of the handle wafer section provides the necessary mechanical support during the thinning process and additional operations, preventing damage to the device layer while enabling the final thin package structure.
2Productivity
If the handle wafer is removed to enable device layer transfer, then package density is improved, but device structure integrity during transfer is compromised
Solution Approach 1:
The handle wafer is divided into a first section for removal (enabling high-density stacking) and a second section for preservation (maintaining device structure integrity). The preserved second section acts as a mechanical handle during the device layer transfer process, ensuring that deep trench capacitors and other sensitive structures remain intact while enabling the final high-density package configuration.
3Strength
If a temporary substrate is used to provide mechanical support during thinning, then mechanical support is maintained, but process complexity increases due to multiple substrate attachment and removal steps
Solution Approach 1:
The second section of the handle wafer serves as a self-provided mechanical support structure during processing. Instead of requiring an external temporary substrate to be attached and later removed, the preserved handle wafer section itself provides the necessary mechanical strength, eliminating the need for additional substrate attachment and removal steps and simplifying the overall process.
Data Source
AI summary
Assemblies including a device layer of a silicon-on-insulator (SOI) substrate and a replacement substrate replacing a handle wafer of the SOI substrate, and methods for transferring the device layer of the SOI substrate from the handle wafer to the replacement substrate. A device structure is formed in a first section of the handle wafer, and a second section of the handle wafer adjoining the first section of the handle wafer is removed to expose a surface of the buried dielectric layer of the silicon-on-insulator substrate. A permanent substrate is attached to the surface of the buried dielectric layer. When the permanent substrate is attached to the surface of the buried dielectric layer, the section of the handle wafer is received inside a cavity defined in the permanent substrate.