Semiconductor Pillar Structure for Reduced Wafer Bowing
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Solution Overview
Problem
Semiconductor structures used in power electronics, photonics, and solar energy conversion face challenges with residual thermal stresses causing bowing and microcracks, particularly when thick films are deposited, making them difficult to handle and process industrially.
Innovation Solution
A method involving a first semiconductor layer with spaced pillars and a second layer of a different semiconductor material, where the aspect ratio of the pillars depends on the dimensions of the second layer, using non-linear functions to optimize the aspect ratio and reduce residual thermal stresses, facilitating industrial-scale manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If thick films of semiconductor material are deposited on bulk layers, then the film thickness increases to meet industrial application requirements, but residual thermal stresses cause excessive bowing and microcrack formation
Solution Approach 1:
The patent divides the continuous thick film into multiple discrete pillars distributed across the bulk layer. This segmentation reduces the cumulative thermal stress in any single continuous region, preventing excessive bowing and microcrack formation while still achieving the required total film thickness through the distributed pillar structure.
Solution Approach 2:
The patent varies the dimensions and spacing of individual pillars across different regions of the bulk layer. By adjusting pillar height, width, and spacing locally, the structure compensates for regional variations in thermal stress, enabling better overall bowing control while maintaining the required thick film coverage.
2Manufacturing precision
If the aspect ratio of pillars is increased to reduce residual thermal stresses, then bowing control improves, but the structure becomes more fragile and difficult to handle
Solution Approach 1:
By segmenting the film into multiple distributed pillars rather than one or few high aspect ratio structures, the patent achieves stress control through numerical distribution. This allows using moderate aspect ratio pillars that are mechanically robust while collectively providing the required stress compensation.
Solution Approach 2:
The patent introduces a distributed pillar structure as an intermediary between the bulk layer and the functional thick film. This intermediary structure provides mechanical support and stress management, allowing the system to achieve bowing control without requiring excessively fragile high aspect ratio pillars.
3Manufacturing precision
If sandwich type structures with thick films on opposite sides are used, then residual thermal stresses are compensated, but the structures become very fragile and difficult to handle
Solution Approach 1:
The patent segments the sandwich structure into multiple discrete pillar regions rather than continuous thick films on opposite sides. This segmentation maintains the stress compensation effect through distributed pillars while significantly improving mechanical robustness and ease of handling by eliminating large continuous fragile regions.
4Manufacturing precision
If optical lithography and selective etching are used to create ridges or pillars, then bowing control improves, but the manufacturing process becomes complex and difficult to apply on industrial scale
Solution Approach 1:
The patent uses segmentation to create the pillar structure, but implements it through straightforward lithographic patterning and etching processes that are already standard in industrial semiconductor manufacturing. The segmented pillar geometry can be defined using conventional lithography tools and etching processes, avoiding the need for complex specialized equipment or multi-step advanced processing.
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 method effectively reduces residual thermal stresses and microcrack formation, enabling easier processing and higher performance semiconductor structures that can be reproducibly manufactured on an industrial scale for electronic devices.
Implementation Method 1
These residual thermal stresses, resulting from the different coefficients of thermal expansion of the semiconductor materials that form the superimposed layers, can easily cause bowing of the structures
Data Source
AI summary
A method for manufacturing a semiconductor structure with reduced bowing for applications in the field of power electronics, photonics, optoelectronics, solar energy conversion and the like, which comprises: - a step of providing at least a first layer of a first semiconductor material, said first layer comprising a substrate of said first semiconductor material, which extends along a first reference plane, and a plurality of first portions of said first semiconductor material, which are mutually spaced and extend in elevation from said substrate along axes perpendicular to said first reference plane, said first portions having ends in distal position with respect to said substrate; - a step of providing at least a second layer of a second semiconductor material, said second layer comprising second portions of said second semiconductor material, each of which is joined to the ends of a plurality of said first portions, said second portions being mutually spaced and extending along a second reference plane parallel to said first reference plane; The first portions of the first layer are produced with an aspect ratio that depends on a dimension of said second portions, measured along said second reference plane. In a further aspect thereof, the invention relates to a semiconductor structure for applications in the field of power electronics, photonics, optoelectronics, solar energy conversion and the like.