Silicon Upper Electrode Cleaning via Oxygen and CF4 Plasma
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Solution Overview
Problem
In plasma processing apparatuses with a silicon upper electrode, the formation of an oxide film due to the reaction between silicon and oxygen ions or radicals leads to particle formation and instability in the plasma state, making it difficult to maintain a stable DC voltage and efficient plasma processing.
Innovation Solution
A method involving two plasma processing steps: first, using oxygen gas plasma to remove attached matter from the silicon surface, and second, using carbon tetrafluoride gas plasma to remove the oxide formed, while controlling pressure and potential differences to prevent oxide film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen gas plasma is used to remove attached matter from the substrate processing chamber, then the reaction product attached to the inner surface is reliably removed, but oxide film is produced through reaction of the silicon upper electrode with oxygen ions and radicals
Solution Approach 1:
The cleaning process is divided into two distinct sequential steps: first using oxygen plasma to remove organic reaction products, then using carbon tetrafluoride plasma to remove the oxide film formed during the first step. This segmentation allows each plasma type to perform its specialized function without the harmful effects accumulating.
Solution Approach 2:
The oxide film formation during oxygen plasma treatment is converted into a beneficial intermediate state that is easily removable by the subsequent carbon tetrafluoride plasma. The harmful oxide is transformed into a temporary layer that facilitates complete cleaning when followed by the fluorocarbon plasma step.
2Productivity
If DC power source is applied to the silicon upper electrode for plasma processing, then plasma processing performance is improved, but the oxide film prevents direct current from passing through
Solution Approach 1:
The oxide film removal step using carbon tetrafluoride plasma is performed as a preliminary action before applying DC power for plasma processing. This ensures the silicon electrode surface is free from insulating oxide layers, allowing DC voltage to be applied effectively and maintaining stable plasma processing performance.
3Reliability
If oxygen plasma is used for cleaning, then attached matter is removed, but particles are produced from peeling oxide film
Solution Approach 1:
The cleaning process maintains continuity by immediately following the oxygen plasma step with carbon tetrafluoride plasma treatment. This continuous action prevents oxide film accumulation and peeling, eliminating particle generation while maintaining the effectiveness of attached matter removal throughout the process.
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
Prevents the formation of oxide films on silicon surfaces within the plasma processing chamber, thereby reducing particle generation and ensuring a stable plasma state, allowing for effective DC voltage application and improved plasma processing performance.
Implementation Method 1
reaction product is removed through reaction with the oxygen ions and oxygen radicals
Implementation Method 2
first plasma produced from oxygen gas introduced into the space
Implementation Method 3
second plasma produced from carbon tetrafluoride gas introduced into the space
Implementation Method 4
second plasma produced from carbon tetrafluoride gas introduced into the space
Data Source
AI summary
A method of cleaning a substrate processing chamber that enables formation of an oxide film on a surface of a processing chamber inside component to be prevented. A substrate processing chamber 11 has therein a processing space S into which a wafer W is transferred and carries out reactive ion etching on the wafer W in the processing space S. The substrate processing chamber 11 has an upper electrode plate 38 that comprises silicon and a lower surface of which is exposed to the processing space S. A dry cleaning is carried out on the upper electrode plate 38 using oxygen radicals produced from oxygen gas introduced into the processing space S. An oxide removal processing is carried out on the upper electrode plate 38 using fluorine ions and fluorine radicals produced from carbon tetrafluoride gas introduced into the processing space S.