Etching Solution for Shallow Trench Isolation Surface Modification
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Solution Overview
Problem
The existing methods for shallow trench isolation in semiconductor manufacturing, such as local oxidation of silicon and sacrificial oxide layers, face issues like surface damage, increased manufacturing time, and cost due to wet etching and complex processes, which affect the quality and yield of semiconductor devices.
Innovation Solution
An etching solution comprising an oxidant and an oxide remover is applied directly to the semiconductor substrate to modify the surface, forming a semiconductor oxide and removing it, thereby improving surface quality and alleviating the 'kooi effect' without complicating the process or increasing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet etching is used to remove the mask layer, then the mask layer is removed, but the etchant erodes the silicon or polysilicon of the silicon chip and damages the surface of the silicon chip
Solution Approach 1:
A buffer layer is introduced as an intermediary between the mask layer and the silicon substrate. This buffer layer absorbs the erosive effect of the etchant during mask layer removal, preventing direct damage to the silicon surface while still allowing effective mask layer stripping
Solution Approach 2:
The buffer layer is deposited beforehand to provide protective cushioning to the silicon substrate. It acts as a sacrificial layer that protects the underlying silicon from etchant damage during subsequent processing steps
2Manufacturing precision
If a sacrificial oxide layer is used to improve surface quality, then the surface quality is improved, but the overall manufacturing time and steps are increased
Solution Approach 1:
The buffer layer serves multiple functions simultaneously: it protects the silicon substrate from etchant damage, provides a surface for mask layer deposition, and can be removed along with the mask layer. This merging of functions eliminates the need for separate sacrificial oxide layer formation and removal steps
Solution Approach 2:
The buffer layer is designed to perform multiple roles in the manufacturing process: substrate protection, mask layer support, and etchant barrier. This multi-functionality reduces the total number of process steps required compared to using dedicated sacrificial oxide layers
3Productivity
If the scale of semiconductor devices decreases, then the integration density increases, but the bird's beak effect reduces the active region length more significantly
Solution Approach 1:
The buffer layer is deposited in advance before trench formation and mask layer deposition. This preliminary action ensures that the silicon surface is protected from oxidation during subsequent processing steps, preventing bird's beak formation at the trench edges and preserving the intended active region dimensions
Solution Approach 2:
The buffer layer provides preliminary anti-action against unwanted oxidation. By having this protective layer in place before thermal oxidation or other processing steps, the silicon substrate is protected from forming the bird's beak structure that would otherwise reduce the active region length
4Ease of manufacture
If nitride residuals remain on the silicon chip after mask layer removal, then the mask layer is removed, but the nitride residuals damage the surface of the silicon chip and lower the yield rate
Solution Approach 1:
The buffer layer acts as an intermediary that captures and holds nitride residuals during mask layer removal. These residuals are trapped in or on the buffer layer rather than remaining on the silicon surface, preventing damage to the chip and maintaining high yield rates
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 solution enhances the surface quality of semiconductor substrates, reduces manufacturing costs, and simplifies the process by using a straightforward etching method that improves the operational stability and quality of semiconductor devices by minimizing the 'kooi effect' and nitride residual damage.
Implementation Method 1
The oxidant is for oxidizing the semiconductor substrate to a semiconductor oxide
Implementation Method 2
The oxide remover is for removing the semiconductor oxide
Data Source
AI summary
An etching solution, a method of surface modification of a semiconductor substrate and a method of forming shallow trench isolation are provided. The etching solution is used for surface modifying the semiconductor substrate. The etching solution includes an oxidant and an oxide remover. The semiconductor substrate is oxidized to a semiconductor oxide by the oxidant, and the oxide remover subtracts the semiconductor oxide.