Wet Etch Rate Control via Chemical Liquid Recycling
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Solution Overview
Problem
In semiconductor manufacturing, particularly for NAND-type nonvolatile storage devices, controlling the etch rate during the slimming process using wet etching is challenging due to variations in etch rate and high costs associated with precise and low etch rate management.
Innovation Solution
A semiconductor manufacturing apparatus and method that utilizes a chemical liquid, such as buffered hydrogen fluoride, which is recycled and adjusted by mixing with water to maintain the etch rate within a predetermined range, allowing for precise control of the etch rate through temperature and concentration management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet etching is used to form fine patterns with low etch rate, then etching precision is improved, but etch rate control difficulty increases and manufacturing cost increases
Solution Approach 1:
The patent implements a feedback control system that monitors the etch rate during the slimming process and adjusts process parameters in real-time to maintain the etch rate within a predetermined range. This automatic feedback mechanism resolves the control difficulty by continuously correcting deviations without manual intervention.
Solution Approach 2:
The patent changes process parameters such as chemical liquid temperature, composition ratio, and flow rate to optimize and stabilize the etch rate. By adjusting these parameters within specific ranges, the system achieves both low etch rate for precision and ease of control through parameter optimization.
2Manufacturing precision
If wet etching is used to form fine patterns with low etch rate, then etching precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent optimizes parameter combinations including chemical liquid temperature (20-40°C), HF concentration (0.1-5%), and NH4F concentration (1-20%) to achieve the desired etch rate while minimizing cost. This parameter optimization allows cost-effective precise etching.
Solution Approach 2:
The patent implements continuous circulation and reuse of the chemical liquid through a closed-loop system, maintaining etch rate stability over extended periods without frequent liquid replacement. This continuous action reduces manufacturing costs by maximizing chemical liquid utilization efficiency.
3Productivity
If chemical liquid is used repeatedly for processing multiple substrates, then productivity is improved, but etch rate stability deteriorates
Solution Approach 1:
The system continuously monitors etch rate during repeated substrate processing and provides feedback to adjust process parameters, ensuring etch rate stability is maintained even as the chemical liquid is reused across multiple substrates.
Solution Approach 2:
The patent adjusts chemical liquid parameters such as temperature and composition ratios during the processing sequence to compensate for changes in liquid properties, thereby maintaining stable etch rate throughout repeated substrate processing and enabling high productivity.
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 enables stable and cost-effective management of the etch rate by adjusting the chemical liquid's concentration and temperature, ensuring consistent etching performance across multiple wafers without the need for frequent chemical liquid replacement.
Implementation Method 1
a slimming process employing wet etching may be carried out to form fine patterns
Implementation Method 2
the chemical liquid used repeatedly and being mixed with water for adjustment of an etch rate
Implementation Method 3
a chemical liquid cycling portion configured to be capable of returning the chemical liquid used in processing the substrate to the chemical liquid storing portion
Data Source
AI summary
A method of manufacturing a semiconductor device includes processing a plurality of substrates each provided with an etch target by using a chemical liquid, the chemical liquid used repeatedly and being mixed with water for adjustment of an etch rate.