CVD Chamber Pre-Oxide Layer Prevents Particle Contamination
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Solution Overview
Problem
Conventional high-density plasma chemical vapor deposition methods fail to prevent particle contamination in semiconductor wafer fabrication, especially in processes with critical dimensions less than 90 nm, due to the stripping of oxide layers from the chamber walls during high-power plasma processes.
Innovation Solution
A method involving higher low-frequency radio frequency (LFRF) power and longer process time for pre-heating and forming a pre-oxide layer on the chamber walls, combined with high-frequency radio frequency (HFRF) bias to direct charged particles and sustain the pre-oxide layer quality, followed by a main oxide layer deposition process and periodic cleaning to manage over-thickened oxide layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-power plasma is applied to improve gapfill ability in processes with critical dimension less than 90 nm, then the gapfill ability is improved, but the oxide layer on the chamber wall strips off more easily causing particle contamination
Solution Approach 1:
A pre-oxide layer is formed on the chamber wall before the main deposition process. This pre-oxide layer serves as a foundation that prevents subsequent oxide layers from stripping off during high-power plasma processes, thereby preventing particle contamination while allowing high-power plasma to be used for improved gapfill ability
Solution Approach 2:
The pre-oxide layer acts as a cushioning layer that absorbs the mechanical stress and adhesion issues that would otherwise cause the oxide layer to strip off during high-power plasma processing. This cushioning effect prevents particle generation while maintaining the benefits of high-power plasma deposition
2Productivity
If conventional HDP-CVD method is used to deposit oxide, then the deposition process is efficient, but oxide thin film forms on the chamber wall and strips off becoming a particle source
Solution Approach 1:
The pre-oxide layer is formed in advance on the chamber wall using a controlled process with silane and oxygen. This preliminary action creates a stable base layer that prevents the cyclic formation and stripping of oxide films during subsequent deposition cycles, eliminating the particle source while maintaining deposition efficiency
3Reliability
If the oxide layer on the chamber wall becomes too thick, then a cleaning process must be performed frequently, but frequent cleaning reduces productivity
Solution Approach 1:
The pre-oxide layer provides a stable foundation that prevents excessive oxide buildup on the chamber wall. By preventing the oxide layer from becoming too thick in the first place, the frequency of cleaning operations is reduced, thereby maintaining chamber reliability while preserving productivity
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 method significantly reduces particle contamination, enhances the adherence of oxide layers, and extends the maintenance cycle of the chamber, improving yield and reducing maintenance costs by forming a robust pre-oxide layer that endures high-power processes.
Implementation Method 1
higher low-frequency radio frequency (LFRF) power and longer process time are used to vacate residual gases in the chamber and perform a pre-heat process
Implementation Method 2
a pre-oxide layer is formed on the chamber wall... silane (SiH4) and oxygen (O2) are introduced to the chamber to form on the chamber wall a pre-oxide layer
Implementation Method 3
high frequency radio frequency (HFRF) is simultaneously provided to the chamber to direct charged particles, and to promote the deposition of an oxide layer
Implementation Method 4
high frequency radio frequency (HFRF) is simultaneously provided to the chamber to direct charged particles
Implementation Method 5
silane and oxygen are introduced to the chamber to form on the chamber wall a pre-oxide layer... silane and oxygen into the chamber to deposit oxide to fill the trenches
Data Source
AI summary
Preventing a chemical vapor deposition (CVD) chamber from particle contamination in which a higher low-frequency radio frequency (LFRF) power and longer process time are provided to vacate the chamber and perform a pre-heat process. Following that, a pre-oxide layer is formed on the chamber wall, while a high-frequency radio frequency bias is provided to the chamber. The high-power LFRF is continuously provided to the chamber to sustain the temperature of the chamber, and then a main oxide layer deposition process is performed. The method is able to form an oxide layer of better quality on a CVD chamber wall, so as to solve the particle problem in the prior art. Therefore, yield is improved and the maintenance cost is reduced.