Tin Oxide Chamber Cleaning Using Two-Step Reducing Plasma
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Solution Overview
Problem
Existing methods for cleaning tin oxide from processing chambers are time-consuming due to the formation of carbon polymer layers and the need for gas flushes to prevent unwanted reactions, limiting the removal rate to about 0.12 μm/hr (2 nm/min) and requiring approximately 17 hours to remove 2 μm of tin oxide.
Innovation Solution
A two-step plasma cleaning process using a first plasma generated from a reducing chemistry, typically hydrogen or ammonia, and optionally inert gas, followed by a second plasma with an organic additive chemistry to convert tin oxide to tin powder, eliminating the need for gas flushes and carbon polymer formation, achieving a removal rate of up to 160 Å/min.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional cleaning methods using carbon-containing plasma are used, then tin oxide can be removed from chamber surfaces, but carbon polymer layers form and require additional gas flushes, extending cleaning time to approximately 17 hours
Solution Approach 1:
The cleaning process is divided into two distinct plasma treatment steps: first using a reducing plasma (H2, NH3, or H2/N2 mixture) to convert tin oxide to tin powder, then using an organic additive plasma to remove the tin powder. This segmentation eliminates the need for carbon polymer formation and gas flushes, reducing cleaning time from 17 hours to under 2 hours while maintaining effective tin oxide removal
Solution Approach 2:
The invention changes the chemical composition parameters of the plasma generation gas, using a two-step approach with different gas chemistries. The first step uses reducing chemistry (H2, NH3, or H2/N2 mixture) to reduce tin oxide, and the second step uses organic additive chemistry to remove the converted tin powder. This parameter change eliminates carbon polymer formation and the associated time losses
2Productivity
If carbon-containing plasma is used to remove tin oxide, then removal is achieved, but carbon polymer formation occurs requiring additional processing steps
Solution Approach 1:
The invention extracts and eliminates the harmful carbon polymer formation step from the cleaning process. By using a reducing plasma first to convert tin oxide to tin powder, then using an organic additive plasma to remove the powder, the process removes the need for carbon-containing plasma and associated gas flushes, simplifying the overall process while maintaining high removal rates
Solution Approach 2:
Instead of using carbon-containing plasma to directly remove tin oxide (which forms carbon polymer), the invention inverts the approach by first using reducing plasma to convert tin oxide to tin powder, then using organic additive plasma to remove the powder. This inverted sequence eliminates carbon polymer formation and reduces process complexity
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 cleaning time to about 2 hours for 2 μm of tin oxide, increasing the removal rate to 1.0 μm/hr (16 nm/min) by avoiding carbon polymer formation and gas flushes, ensuring uniformity and efficiency in the cleaning process.
Implementation Method 1
exposing the chamber surface to a first plasma generated from a first plasma generation gas including a first reducing chemistry to reduce the tin oxide to tin powder
Implementation Method 2
a first reducing chemistry to reduce the tin oxide to tin powder
Implementation Method 3
exposing the chamber surface to a second plasma generated from a second plasma generation gas including a second reducing chemistry and organic additive chemistry to remove the tin powder from the chamber surface
Data Source
AI summary
Techniques described herein relate to methods and apparatus for minimizing tin oxide chamber clean time. In many cases, the chamber is a deposition chamber used for depositing tin oxide on semiconductor substrates. The techniques involve exposing the chamber surface to a first plasma generated from a first plasma generation gas including reducing chemistry to reduce the tin oxide to tin, and then exposing the chamber surface to a second plasma generated from a second plasma generation gas including reducing chemistry and organic additive chemistry to remove the tin from the chamber surface. In some cases, the first plasma used to reduce the tin oxide to tin further includes inert gas.