Epitaxial Wafer Production with Cleaning and Recipe Control
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Solution Overview
Problem
The existing methods for producing epitaxial wafers using single wafer processing epitaxial growth furnaces face challenges in maintaining uniform quality between successive wafers due to deposit buildup, leading to quality degradation and low productivity, as cleaning processes are inefficient and often result in varying film thickness profiles.
Innovation Solution
A method involving a cleaning process followed by two distinct wafer processing steps using different control parameters for reactive and inert gas flow rates, ensuring consistent film thickness profiles across multiple epitaxial wafers produced between cleaning cycles, with an apparatus that stores and controls these recipes to manage the epitaxial growth furnace operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cleaning process is performed after every epitaxial growth process to remove deposit, then the quality of epitaxial wafers is maintained, but productivity and operating efficiency decrease
Solution Approach 1:
The patent applies preliminary action by performing a cleaning process before a predetermined number of epitaxial growth processes rather than after each individual process. This preventive cleaning approach removes deposits before they accumulate to levels that would cause quality degradation, thereby maintaining wafer quality while reducing the total number of cleaning cycles and improving productivity.
2Productivity
If the number of epitaxial growth processes is increased before cleaning to improve productivity, then operating efficiency improves, but deposit falls off and adheres to wafer surface degrading quality
Solution Approach 1:
The patent implements feedback by experimentally determining the maximum number of epitaxial growth processes that can be performed before deposit accumulation causes quality degradation. This predetermined limit is established based on monitoring deposit formation, and the cleaning schedule is adjusted according to this feedback to maintain optimal wafer quality while maximizing productivity.
3Device complexity
If the same process recipe is used for all wafers after cleaning, then process simplicity is maintained, but film thickness profile varies between first and subsequent wafers
Solution Approach 1:
The patent applies local quality by differentiating the processing approach for the first wafer versus subsequent wafers after cleaning. The first wafer receives a initial process recipe that accounts for the freshly cleaned state, while subsequent wafers receive a different recipe optimized for the established process conditions. This localized differentiation ensures consistent film thickness profiles across all wafers while maintaining overall process simplicity.
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
This approach allows for the successful production of epitaxial wafers with uniform quality, improving productivity by maintaining consistent film thickness profiles and reducing the variation in wafer quality, thereby enhancing the efficiency of the epitaxial wafer production process.
Implementation Method 1
a wafer mounted on a susceptor in an epitaxial growth furnace is heated to a high temperature and rotated at the same time, and a silicon reactive gas using hydrogen carriers is introduced to generate a silicon thin film on the surface of the wafer
Implementation Method 2
a cleaning process is performed through predetermined steps by supplying a cleaning gas such as hydrochloric gas or chlorine trifluoride gas into the epitaxial growth furnace
Data Source
AI summary
After removing deposit on a susceptor in an epitaxial growth furnace by a cleaning recipe (step S101), a first epitaxial wafer is produced by growing an epitaxial layer on a first wafer based on a process recipe A (step S102). Subsequently, a step of producing an epitaxial wafer by growing an epitaxial layer on a wafer based on a process recipe B including second control parameters set such that the epitaxial wafer has approximately the same film thickness profile as the first wafer (step S103) is repeated a plurality of times to successively produce a plurality of epitaxial wafers (step S104). The cleaning recipe, the process recipe A, and the process recipe B repeated a plurality of times are carried out repeatedly (step S105).