Polysilicon Surface Roughness Reduction via Oxide Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polysilicon layers exhibit surface roughness, which increases leakage current and reduces the breakdown electric field of semiconductor devices, posing a significant technical challenge.
Innovation Solution
A method and system involving the deposition of a polysilicon layer, followed by forming an oxide layer on its surface using chemical vapor deposition, and then etching this oxide layer with a buffered oxide etchant to smooth out protrusions, thereby reducing surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polysilicon layer is obtained by processing amorphous silicon, then the polysilicon layer can be formed, but surface roughness occurs with protrusions between 10 nm and 20 nm
Solution Approach 1:
An oxide layer is deposited on the polysilicon layer surface before final device fabrication, covering the protrusions in advance. This preliminary action prepares the surface for subsequent etching to remove the protrusions and reduce surface roughness
Solution Approach 2:
An oxide layer is introduced as an intermediary material between the polysilicon layer and the final device structure. This oxide layer serves as a mask and protective layer during the etching process, enabling selective removal of protrusions while protecting underlying structures
2Reliability
If surface roughness of the polysilicon layer is reduced, then leakage current decreases, but additional processing steps are required
Solution Approach 1:
The oxide layer deposition and subsequent etching steps are integrated into the existing polysilicon fabrication process flow. The oxide layer is deposited using standard CVD equipment already present in semiconductor manufacturing, and the etching is performed using buffered oxide etchant that can be applied through existing wet processing lines, merging multiple functions into unified process steps
3Reliability
If surface roughness is reduced to minimize leakage current, then breakdown electric field increases, but process time increases
Solution Approach 1:
The etching process uses buffered oxide etchant with controlled concentration and temperature parameters to achieve optimal etching rate. The etching time and etchant composition are carefully adjusted to remove protrusions efficiently while minimizing overall process time and maximizing surface smoothness
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 effectively reduces surface roughness, minimizing leakage current and enhancing the breakdown electric field of semiconductor devices by smoothing the polysilicon layer surface.
Implementation Method 1
depositing an oxide on the surface of the polysilicon layer by chemical vapor deposition to form the oxide layer
Implementation Method 2
etching the oxide layer with a buffered oxide etchant
Data Source
AI summary
The present disclosure provides a method and system for fabricating a semiconductor device. The method and system of the present disclosure, after obtaining the polysilicon layer, first form the protective oxide layer on the surface of the polysilicon layer, and then etch the protective oxide layer and the protrusions on the surface of the polysilicon layer with the buffered oxide etchant based on controllability of the buffered oxide etchant, thereby reducing the protrusions on the surface of the polysilicon layer, while well protecting the surface of the polysilicon layer. Therefore, the technical problem of surface roughness in the existing polysilicon layers is solved.