Two-Stage Etching for Tungsten and Titanium Nitride Films
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Solution Overview
Problem
The existing etching processes for semiconductor manufacturing face inefficiencies in etching films like tungsten and titanium nitride, particularly in achieving high accuracy and efficiency due to variations in etching rates and selectivity, which can lead to prolonged processing times and potential over-etching.
Innovation Solution
A substrate processing method that involves a two-stage etching process with a chemical liquid containing phosphoric acid, acetic acid, nitric acid, and water, where the etching rate is initially increased for rapid tungsten film etching and then adjusted to match the titanium nitride etching rate by changing the liquid's composition or temperature, ensuring precise control and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single etching rate is used for both tungsten film and titanium nitride film, then the etching process is simple, but the etching accuracy and selectivity deteriorate
Solution Approach 1:
The etching process is divided into two distinct stages: a first etching stage using a first chemical liquid optimized for tungsten film etching, and a second etching stage using a second chemical liquid optimized for titanium nitride film etching. This segmentation allows each stage to be optimized for its specific target material, thereby achieving high etching accuracy and selectivity for both films without compromising process simplicity
Solution Approach 2:
The patent changes the chemical composition parameters between stages by using different chemical liquids with specific formulations. The first chemical liquid contains components optimized for tungsten etching, while the second chemical liquid contains components optimized for titanium nitride etching. This parameter change enables selective etching control, achieving high precision for both materials
2Productivity
If a high etching rate is used for tungsten film, then processing time is reduced, but selectivity control deteriorates
Solution Approach 1:
The etching process is segmented into two stages with different rate characteristics. The first etching stage uses a chemical liquid and conditions optimized for high etching rate to efficiently remove tungsten film, while the second etching stage uses a different chemical liquid optimized for selective etching of titanium nitride film, thereby achieving both high productivity and precise selectivity control
Solution Approach 2:
The patent changes chemical composition parameters between stages. The first chemical liquid is formulated to achieve high etching rate for tungsten, while the second chemical liquid is formulated to provide selective etching for titanium nitride. This parameter change enables the system to achieve high productivity in the first stage and precise selectivity in the second stage
3Manufacturing precision
If the etching rate is changed during processing, then etching accuracy is improved, but processing time increases
Solution Approach 1:
The etching process is segmented into two efficient stages. The first stage quickly etches the tungsten film using a chemical liquid optimized for high-rate tungsten etching, minimizing time loss. The second stage then precisely etches the titanium nitride film using a different chemical liquid optimized for selective etching. This segmentation achieves high etching accuracy while minimizing total processing time by optimizing each stage for its specific purpose
Solution Approach 2:
The first etching stage performs preliminary action by efficiently removing the tungsten film before the second stage begins. This preliminary high-rate etching reduces the overall processing time required, while the subsequent second stage ensures high accuracy for the titanium nitride film etching
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 reduces processing time for the initial etching stage while ensuring high accuracy in the second stage, allowing for efficient and precise etching of both films with controlled selectivity, thereby improving overall processing efficiency and accuracy.
Implementation Method 1
an etching process for etching a film formed on a substrate such as a semiconductor wafer has been known as one of semiconductor manufacturing processes
Data Source
AI summary
A substrate processing method includes etching a substrate having a first film and a second film at a first etching rate; changing an etching rate from the first etching rate to a second etching rate; and etching the substrate at the second etching rate.