Semiconductor Device with Low-Temperature Oxide Diffusion Barrier
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Solution Overview
Problem
In microphone manufacturing, thermal processes cause chromium (Cr) to diffuse into the gold (Au) layer, forming chromium oxide, which weakens wire connections and can lead to bond failure, and conventional methods to prevent diffusion often result in incomplete removal of polymer residues during Deep Reactive Ion Etching, causing detection problems.
Innovation Solution
A semiconductor device manufacturing method involving a substrate structure with a chromium layer, a gold layer, and a silicon-based oxide layer formed at a lower temperature, followed by thermal processes at a higher temperature, which reduces Cr diffusion into the Au layer and facilitates complete removal of polymer residues using Buffer Oxide Etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal processes are conducted at high temperature to remove polymer residues, then polymer removal is complete, but Cr diffuses into the Au layer forming chromium oxide
Solution Approach 1:
A low-temperature oxide layer is formed on the Au layer before subsequent high-temperature thermal processes. This preliminary oxide layer acts as a diffusion barrier that prevents Cr from migrating into the Au layer during high-temperature processing, while allowing complete polymer residue removal. The oxide layer is formed at a lower temperature (e.g., 400-600°C) before the high-temperature steps (e.g., >600°C) that would otherwise cause Cr diffusion.
Solution Approach 2:
The low-temperature oxide layer serves as an intermediary protective layer between the Cr layer and the Au layer. This intermediate oxide barrier physically blocks the diffusion path of Cr atoms during high-temperature processing, preventing direct interaction between Cr and Au that would form harmful chromium oxide compounds.
2Object-generated harmful factors
If peak temperature is capped to prevent Cr diffusion, then chromium oxide formation is reduced, but polymer residues cannot be completely removed
Solution Approach 1:
The oxide layer is formed as a preliminary protective barrier before high-temperature processing. This allows the subsequent thermal processes to be conducted at sufficiently high temperatures to completely remove polymer residues without concern for Cr diffusion, since the oxide layer already provides the necessary protection.
Solution Approach 2:
The potential harm of high-temperature processing (Cr diffusion) is converted into a benefit by first creating an oxide layer that protects the Au layer. The high temperature that would normally cause problems is now utilized effectively to remove polymer residues completely, while the oxide layer prevents the harmful Cr diffusion.
3Object-generated harmful factors
If a low-temperature oxide layer is formed on the Au layer, then Cr diffusion is prevented during high-temperature processes, but an additional process step is required
Solution Approach 1:
The low-temperature oxide layer formation process serves multiple functions: it protects the Au layer from Cr diffusion during subsequent high-temperature processing, and can also serve as part of the overall device structure or interface layer. This multi-functionality justifies the additional process step by providing both protection and structural utility.
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 method effectively reduces Cr concentration on the Au layer, preventing chromium oxide formation and ensuring stable metal wire connections by filling grain boundaries with the oxide layer, thereby enhancing the reliability of wire bond pads.
Implementation Method 1
forming a first oxide layer on the second metal layer at a first temperature... conducting remaining manufacturing processes including thermal processes at a second temperature higher than the first temperature... effectively reduces Cr concentration on the Au layer, preventing chromium oxide formation
Implementation Method 2
filling grain boundaries with the oxide layer, thereby enhancing the reliability of wire bond pads
Implementation Method 3
facilitates complete removal of polymer residues using Buffer Oxide Etching
Data Source
AI summary
A semiconductor device and its manufacturing method are presented. The manufacturing method includes providing a substrate structure; forming a first metal layer on the substrate structure; forming a second metal layer on the first metal layer; forming a first oxide layer on the second metal layer at a first temperature; and conducting the remaining manufacturing processes including thermal processes at a second temperature that is higher than the first temperature. This method reduces the concentration of the first metal diffused into the surface of the second metal layer during the thermal processes, thus reducing the amount of the oxide of the first metal formed on the surface of the second metal layer. Therefore, it is beneficial to the establishment of metal wire connections.