Direct Bonded SOI Wafer Edge Oxide Removal
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Solution Overview
Problem
The existing methods for manufacturing direct bonded SOI wafers result in exposed buried oxide film edges, leading to mechanical weakness, pattern defects, and increased manufacturing costs due to additional processing steps required to cover and remove the oxide film.
Innovation Solution
A method that involves forming a laminated body of semiconductor and support wafers via an oxide film, with the entire buried oxide film layer being covered on the laminating side of the support wafer, and removing the oxide film from the circumferential end edges and chamfered portions to prevent exposure, thereby reducing manufacturing costs and improving wafer quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the semiconductor wafer and support wafer are bonded via an oxide film and the semiconductor wafer is thinned to form a thin-film single crystal silicon layer, then an SOI wafer is obtained, but the end edges of the buried oxide layer are exposed on the side face causing mechanical weakness and pattern defects
Solution Approach 1:
The patent applies preliminary action by forming a protective film on the oxide film layer before bonding, and by designing the bonding structure to inherently cover the oxide film edges. The protective coating is applied in advance to prevent the harmful effect of exposed oxide edges before they can cause mechanical weakness or pattern defects during subsequent processing.
2Manufacturing precision
If the exposed end edges of the oxide film are removed by etching with fluorinated acid solution, then pattern defects are prevented, but the manufacturing cost increases due to additional processing steps
Solution Approach 1:
The patent extracts the harmful exposed oxide film edges through selective etching using fluorinated acid solution. By removing only the exposed oxide edges and not the entire oxide layer, the method prevents pattern defects while minimizing additional processing requirements. The selective removal targets only the problematic portions that cause harm.
Solution Approach 2:
The patent discards the harmful exposed oxide film edges through selective etching, removing only the portions that cause mechanical weakness and pattern defects. The bulk oxide film layer is preserved and recovered for its essential function as the buried oxide layer in the SOI structure, maintaining electrical isolation while eliminating the harmful exposed edges.
3Strength
If a protective coating is applied to cover the oxide film layer on the side face, then mechanical strength is improved, but the manufacturing cost increases due to additional coating and removal processes
Solution Approach 1:
The patent applies preliminary action by forming a protective film on the oxide film layer before bonding occurs. This pre-applied protective coating prevents the exposed oxide edges from causing mechanical weakness during subsequent processing, eliminating the need for later protective measures and reducing overall manufacturing 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 prevents the exposure of buried oxide film edges, enhances the mechanical strength and quality of the SOI wafer, and reduces manufacturing costs by eliminating unnecessary processing steps.
Implementation Method 1
a semiconductor wafer and a support wafer are bonded together via an oxide film
Implementation Method 2
the exposed end edges 3a, 3a of the oxide film 3 are removed at the etching by a fluorinated acid solution
Data Source
AI summary
A direct bonded SOI wafer having an entire buried oxide film layer covered and not exposed is manufactured by: (A) forming a laminated body by laminating a semiconductor wafer and a support wafer via an oxide film; and (B) forming a thin-film single crystal silicon layer on the support wafer using a buried oxide film layer by film-thinning the semiconductor wafer to a predetermined thickness. In a process (C) the entire buried oxide film layer is covered by a main surface on the laminating side of the support wafer and the single crystal silicon layer. The covering of the entire buried film layer is carried out by, between process (A) and (B), removing the oxide film formed on the circumferential end edge of the main surface on the laminating side and the chamfered portion to leave the oxide film only on the laminated surface except the circumferential end edge.