Annealing Process for Uniform Oxide Layer on Semiconductor Wafers
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Solution Overview
Problem
The existing processes for fabricating multilayer semiconductor substrates, such as BSOI structures, often result in defects like nicks on the edges of the second wafer during chemical etching steps, which can lead to contamination and non-optimized fabrication, affecting the quality of the multilayer structures and subsequent technological steps.
Innovation Solution
A process involving multiple annealing steps in an oxidizing atmosphere, where the structure is shifted between annealings to ensure uniform oxide layer formation on all exposed surfaces, preventing the formation of nicks by protecting the regions that would otherwise be exposed to chemical etches during trimming and thinning operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single annealing step is performed in an oxidizing atmosphere, then the structure is quickly protected from chemical etching, but non-uniform oxide layer formation occurs leaving regions vulnerable to etching damage
Solution Approach 1:
The annealing process is divided into multiple sequential annealing steps, each forming oxide layers on different portions of the structure. The first annealing step forms an oxide layer on a first portion of the exposed surface, while the second annealing step forms an oxide layer on a second portion of the exposed surface that was not covered during the first step. This segmentation ensures complete and uniform coverage of the entire exposed surface.
Solution Approach 2:
The method performs preliminary oxidation on portions of the structure before they are exposed to chemical etching. By conducting the first annealing step before the second, the process ensures that all regions will have oxide protection before the structure undergoes chemical etching operations, preventing nick formation on the second wafer.
2Ease of operation
If the structure is held in a fixed position during annealing, then the process is simple to operate, but regions in contact with the holder remain unoxidized and susceptible to chemical etching
Solution Approach 1:
The method introduces dynamic repositioning of the structure between annealing steps. The structure is shifted from a first position during the first annealing step to a second position during the second annealing step. This dynamic adjustment ensures that regions in contact with the holder during the first step are exposed to the oxidizing atmosphere during the second step, achieving complete oxide coverage while maintaining operational simplicity.
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 ensures the formation of a uniform oxide layer that protects the structure from chemical etches, preventing defects like nicks and enhancing the quality of the multilayer structures by maintaining the integrity of the substrate during subsequent processing steps.
Implementation Method 1
conducting a first annealing of the structure in an oxidizing atmosphere while holding the structure in contact with a holder in a first position in order to oxidize at least portion of the exposed surface of the structure
Data Source
AI summary
The invention relates to a process for annealing a structure that includes at least one wafer, with the annealing process including conducting a first annealing of the structure in an oxidizing atmosphere while holding the structure in contact with a holder in a first position in order to oxidize at least portion of the exposed surface of the structure, shifting the structure on the holder into a second position in which non-oxidized regions of the structure are exposed, and conducting a second annealing of the structure in an oxidizing atmosphere while holding the structure in the second position. The process provides an oxide layer on the structure.