Amorphous Silicon Capping Layer Prevents Aluminum Fluoride Sublimation
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Solution Overview
Problem
In semiconductor industry plasma reactors, aluminum fluoride layers form on chamber components during etching processes, leading to contamination and unstable etch rates due to high vapor pressure and sublimation, with no effective in-situ cleaning methods available.
Innovation Solution
A method involving purging the processing chamber with a chemically reactive gas at specific flow rates and pressures, generating plasma to remove residues, and depositing an amorphous silicon layer to prevent aluminum fluoride sublimation, using a two-stage plasma process and silane gas to scavenging fluorine radicals and depositing a capping layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If aluminum-containing materials are used in plasma reactors, then device durability and ease of manufacture are improved, but aluminum fluoride deposition forms on chamber components causing contamination and etch rate drift
Solution Approach 1:
A boron-containing compound is introduced as an intermediary substance that reacts with aluminum fluoride to form a volatile complex. This mediator enables the removal of aluminum fluoride contamination without requiring disassembly of chamber components, thus resolving the contradiction between ease of manufacture and harmful deposition.
Solution Approach 2:
The invention converts the harmful aluminum fluoride deposition into a removable volatile complex by reacting it with boron-containing compounds. The harmful aluminum fluoride that would otherwise contaminate substrates is transformed into a volatile species that can be easily evacuated, turning the contamination problem into a solvable chemical reaction.
2Productivity
If aluminum fluoride layer forms on chamber components, then etching process can proceed, but the aluminum fluoride sublimes at high temperature and contaminates substrate surface
Solution Approach 1:
The boron-containing compound is introduced during the etching process to preemptively react with aluminum fluoride before it can sublime and contaminate substrates. This preliminary chemical action prevents the harmful transfer of aluminum fluoride to substrates while maintaining etching productivity.
Solution Approach 2:
The boron-containing compound acts as a mediator that intercepts aluminum fluoride in the vapor phase, forming a volatile complex that is evacuated from the chamber. This prevents aluminum fluoride from reaching and contaminating substrate surfaces during the etching process.
3Reliability
If conventional cleaning methods are used, then some residue removal is achieved, but aluminum fluoride on faceplate cannot be removed and chamber stability deteriorates
Solution Approach 1:
The invention changes the chemical parameters of the cleaning process by introducing boron-containing compounds that react with aluminum fluoride to form volatile complexes. This chemical parameter change enables the removal of persistent aluminum fluoride deposits that conventional physical cleaning methods cannot remove, thereby restoring chamber stability.
Solution Approach 2:
The persistent aluminum fluoride contamination is converted into a removable volatile complex through chemical reaction with boron-containing compounds. This transformation turns the previously intractable contamination problem into an easily removable species, restoring chamber reliability and stability.
4Productivity
If high RF power density is used to generate plasma for cleaning, then cleaning efficiency is improved, but excessive heat causes aluminum fluoride to sublime and deposit on faceplate
Solution Approach 1:
The boron-containing compound serves as a chemical intermediary that reacts with aluminum fluoride at lower temperatures to form volatile complexes. This chemical mechanism enables effective cleaning without requiring high RF power density that would cause thermal sublimation, thus resolving the contradiction between cleaning efficiency and thermal damage.
Solution Approach 2:
The invention replaces the mechanical/thermal cleaning mechanism (high RF power plasma) with a chemical reaction mechanism using boron-containing compounds. This substitution allows for effective aluminum fluoride removal through chemical volatility enhancement rather than thermal sublimation, avoiding faceplate contamination.
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
Effectively prevents aluminum fluoride contamination, stabilizes etch rates, and extends the life of chamber components by maintaining chamber stability and reducing residue accumulation.
Implementation Method 1
the purging gas is chemically reactive with deposition residue on exposed surfaces of the substrate processing chamber
Implementation Method 2
removing a deposition residue from interior surfaces of the substrate processing chamber by generating a plasma from the cleaning gas
Implementation Method 3
formation of the aluminum fluoride has significant vapor pressure above 480 degree Celsius and starts subliming at this temperature
Implementation Method 4
the purging gas deposits an amorphous silicon layer on a surface of a substrate support disposed within the substrate processing chamber
Data Source
AI summary
Implementations of the present disclosure provide methods for treating a processing chamber. In one implementation, the method includes purging a 300 mm substrate processing chamber, without the presence of a substrate, by flowing a purging gas into the substrate processing chamber at a flow rate of about 0.14 sccm/mm2 to about 0.33 sccm/mm2 and a chamber pressure of about 1 Torr to about 30 Torr, with a throttle valve of a vacuum pump system of the substrate processing chamber in a fully opened position, wherein the purging gas is chemically reactive with deposition residue on exposed surfaces of the substrate processing chamber.