Semiconductor Device Alpha Ray Shielding Metallic Layer
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Solution Overview
Problem
As semiconductor devices increase in size and capacity while lowering voltage, the soft error rate per unit cell of SRAMs is elevated due to alpha rays emitted from resin layers in the wiring substrate, which can cause data errors in the SRAM of the controller chip.
Innovation Solution
A metallic layer, preferably made of copper with a thickness between 23 micrometers and 58 micrometers, is embedded between the SRAM and the wiring substrate to absorb alpha rays, reducing the thickness of the semiconductor substrate and protecting the SRAM from data errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the semiconductor substrate is reduced to enable downscaling, then the device size and capacity are improved, but the soft error rate increases due to alpha rays from the wiring substrate
Solution Approach 1:
A metallic layer is introduced as an intermediary substance between the SRAM and the wiring substrate. This metallic layer serves as a mediator that absorbs alpha rays emitted from the wiring substrate, preventing them from reaching the SRAM and causing soft errors, while allowing the semiconductor substrate thickness to be reduced for downscaling.
Solution Approach 2:
The harmful alpha rays emitted from the wiring substrate are converted into a beneficial effect by using a metallic layer to absorb them. The alpha rays, which would otherwise cause soft errors in the SRAM, are now utilized to test and validate the effectiveness of the metallic layer as a radiation shielding mechanism.
2Reliability
If a metallic layer is added to absorb alpha rays and reduce soft errors, then the reliability is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The metallic layer serves multiple functions simultaneously: it acts as an alpha ray absorption shield to prevent soft errors, provides an additional conductive layer for electrical connections, and can serve as a barrier layer to prevent diffusion between different materials. This multi-functionality reduces the need for separate dedicated shielding structures.
Solution Approach 2:
The radiation shielding function is merged with existing metallic layers in the semiconductor structure, such as interconnect layers or barrier layers. By combining the shielding function with already-present metallic structures, the patent avoids adding separate dedicated shielding components, thereby reducing overall device complexity.
3Reliability
If the metallic layer thickness is increased to improve alpha ray absorption, then the soft error suppression is enhanced, but the manufacturing precision requirements and cost increase
Solution Approach 1:
The patent specifies an optimal thickness range (23-58 micrometers) for the metallic layer that balances alpha ray absorption effectiveness with manufacturing feasibility. This parameter optimization ensures sufficient radiation shielding while remaining within the capabilities of standard semiconductor manufacturing processes, avoiding excessive thickness control precision requirements.
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
The metallic layer effectively suppresses soft errors in the SRAM by absorbing alpha rays, allowing for a reduction in the thickness of the semiconductor device while maintaining data integrity, enabling the downscaling of SRAMs and reducing the overall size of the semiconductor package.
Implementation Method 1
A metallic layer, preferably made of copper with a thickness between 23 micrometers and 58 micrometers, is embedded between the SRAM and the wiring substrate to absorb alpha rays
Data Source
AI summary
A semiconductor device according to the present embodiment includes a wiring substrate. A semiconductor chip includes a semiconductor substrate having a first face and a second face on the opposite side to the first face, and an SRAM on the side of the first face, and is stuck to the wiring substrate on the side of the second face. The semiconductor chip includes a first metallic layer provided in the semiconductor substrate between the SRAM and the wiring substrate.