UV Transmissive Sapphire Window for Fluorine Cleaning
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Solution Overview
Problem
Semiconductor substrate processing chambers face contamination and yield loss due to solid residues accumulating on internal surfaces, which require effective cleaning chemistries that are compatible with chamber materials, especially when dealing with silicon-containing residues that necessitate fluorine-containing chemistries, posing incompatibility issues with materials like quartz windows.
Innovation Solution
A semiconductor processing apparatus with a UV transmissive window made of sapphire or other non-reactive materials, potentially in a dual pane configuration with a purge gas flow path, allowing for the use of fluorine-containing cleaning chemistries without reacting with the window materials, and a system that includes a UV source to convert oxygen into ozone for cleaning, maintaining pressure equivalence between the window panes and chamber interior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorine-containing chemistries are used to clean silicon-containing residues, then cleaning effectiveness is improved, but compatibility with chamber materials (e.g., quartz windows) deteriorates
Solution Approach 1:
The window assembly is segmented into multiple layers: a fluorine-resistant material layer (e.g., sapphire, silicon oxide, silicon nitride) positioned between the quartz window and the chamber interior. This segmentation allows the quartz window to maintain its structural and optical functions while the fluorine-resistant layer provides chemical protection during cleaning operations.
Solution Approach 2:
A fluorine-resistant coating or overlay material serves as an intermediary between the fluorine-containing cleaning chemistry and the quartz window. This intermediary layer is chemically resistant to fluorine, preventing direct reaction with the quartz while still allowing UV radiation to pass through for substrate processing.
2Object-affected harmful factors
If UV transmissive windows are made from fluorine-resistant materials like sapphire, then compatibility with fluorine-containing chemistries is improved, but UV transmission efficiency may deteriorate
Solution Approach 1:
The window system is divided into multiple functional layers: a thin fluorine-resistant coating (such as silicon oxide or silicon nitride) applied to the quartz window surface. This segmentation allows the bulk quartz material to provide high UV transmission while the thin protective layer provides fluorine resistance without significantly blocking UV radiation.
Solution Approach 2:
The window assembly uses composite construction combining quartz (for UV transmission) with a fluorine-resistant coating layer (for chemical resistance). This composite structure integrates the complementary properties of both materials to achieve both high UV transmission and fluorine chemical compatibility.
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 solution effectively prevents contamination by ensuring compatibility with fluorine-containing cleaning chemistries, maintaining chamber integrity, and achieving uniform wafer processing by using sapphire windows and ozone generation for residue removal, thus enhancing processing reliability and yield.
Implementation Method 1
a UV source disposed outside the chamber to shine UV radiation into the chamber through the UV transmissive window
Data Source
AI summary
Apparatuses and methods for cleaning a semiconductor processing chamber is provided. The semiconductor processing chamber may include a UV radiation source, a substrate holder, and a UV transmissive window. The UV transmissive window may include one or multiple panes. One or more panes of the UV transmissive window may be non-reactive with fluorine containing chemistries. In multi-pane windows a purge gas flow path may be formed in the gap between windows. A purge gas may be flowed through the purge gas flow path to prevent process gases used in the chamber interior from reaching one or more panes of the UV transmissive window.