Dry Etching Method for Semiconductor Device Manufacturing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor device manufacturing, dry etching with small opening ratios poses challenges in controlling processing dimensions and detecting end points, leading to etching rate variations and reliability issues in MISFETs due to changes in etching apparatus conditions.
Innovation Solution
A method is developed to calculate the first etching rate by correlating opening ratios with etching rates, allowing for time-controlled etching on a second wafer using the first etching rate, even when the etching rate shifts, to maintain processing accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If time-controlled etching is used with small opening ratios, then productivity is improved, but manufacturing precision deteriorates due to etching rate variations
Solution Approach 1:
The patent performs preliminary etching at a first opening ratio to measure the actual etching rate before the main etching step. This preliminary action establishes the correlation between opening ratio and etching rate, allowing subsequent time-controlled etching to use accurate, pre-determined etching times that compensate for apparatus variations, thereby maintaining manufacturing precision while enabling high-speed processing.
2Manufacturing precision
If endpoint detection is used for etching control, then manufacturing precision is improved, but ease of operation deteriorates due to difficulty in detecting endpoint with small opening ratios
Solution Approach 1:
Instead of attempting to detect the endpoint directly during etching of patterns with small opening ratios (which is difficult), the patent inverts the approach by performing etching at a different opening ratio where endpoint detection is easy, measuring the etching rate, and then applying this information to control the main etching process through time control. This inversion transforms an inoperable detection problem into a solvable measurement and calculation problem.
3Ease of operation
If etching rate is assumed constant for time-controlled etching, then ease of operation is improved, but reliability deteriorates due to etching rate shifts
Solution Approach 1:
The patent implements a feedback mechanism where the etching rate is measured through preliminary etching steps and this measured rate is fed back to determine the etching time for subsequent processing steps. This feedback loop continuously updates the etching rate parameter based on actual apparatus performance, maintaining reliability while preserving the simplicity of time-controlled etching operations.
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 ensures high reliability of semiconductor devices by accurately controlling etching dimensions and preventing threshold value changes in MISFETs, reducing defects and maintaining processing shape and dimension consistency.
Implementation Method 1
dry etching process
Implementation Method 2
dry etching process
Data Source
AI summary
A first etching rate of the first conductive film is calculated by acquiring correlation between an opening ratio of an etching mask and an etching rate of an etching target film, and then, performing a first dry etching to a first conductive film formed on a first wafer. Next, a second etching mask is formed on a second conductive film formed on a second wafer, and an etching time of the second conductive film is determined from the correlation between the opening ratio and the etching rate, the first etching rate, and a film thickness of the second conductive film when the second conductive film is subjected to a second dry etching in time-controlled etching.