Plasma Etching Gas Flow Modulation for Pattern Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in semiconductor device manufacturing is forming fine patterns with high accuracy and selectivity, particularly for miniaturized circuit patterns, as existing plasma etching techniques struggle to uniformly create thin and deep holes or line-and-space patterns with high selectivity due to trade-offs between pattern shape and selectivity.
Innovation Solution
A semiconductor device manufacturing method involving a plasma etching process where a gaseous mixture is supplied in alternating flow rates within a processing chamber, with each flow rate setting maintained for specific time periods without extinguishing the plasma, ensuring the total flow rates in both settings are substantially equal or differ by no more than 10%, to achieve consistent plasma state and improved etching precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flow rate of etching gas is increased to improve etching speed, then productivity is improved, but manufacturing precision deteriorates due to loss of selectivity and pattern shape control
Solution Approach 1:
The patent applies periodic action by alternately changing the flow rate of etching gas between a first value (higher flow rate for faster etching) and a second value (lower flow rate for better selectivity and pattern control) during the plasma etching process. This periodic variation in gas flow rate allows the system to achieve both high etching speed and high manufacturing precision by switching between different flow rate conditions at appropriate intervals during the etching cycle.
2Manufacturing precision
If the flow rate of etching gas is decreased to improve selectivity and pattern shape, then manufacturing precision is improved, but productivity deteriorates due to reduced etching speed
Solution Approach 1:
The patent implements periodic action by periodically switching the etching gas flow rate between a first value (lower flow rate that provides high selectivity and good pattern shape) and a second value (higher flow rate that provides fast etching speed). This periodic modulation allows the process to maintain high manufacturing precision during phases requiring selectivity while achieving high productivity during phases requiring rapid material removal, thereby resolving the contradiction between precision and speed.
3Manufacturing precision
If a nitride film is formed on the substrate surface to prevent undercut during intermittent etching, then manufacturing precision is improved, but device complexity increases due to additional film formation steps
Solution Approach 1:
The patent extracts and eliminates the need for separate nitride film formation steps by directly controlling the plasma etching process through periodic flow rate modulation. Instead of adding a protective nitride film layer and subsequent removal steps, the invention achieves undercut prevention by taking out the film formation complexity and replacing it with a simplified gas flow control mechanism that directly manages the etching process to prevent undercut formation.
Solution Approach 2:
The patent introduces the periodic flow rate modulation as an intermediary control mechanism between the etching gas supply and the substrate. This intermediary approach allows dynamic adjustment of etching conditions during the process, enabling precise control over the etching front to prevent undercut without requiring additional protective films or complex multi-step processes.
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 method enables the formation of fine patterns with enhanced accuracy and selectivity, improving the uniformity and effectiveness of the etching process, as demonstrated by improved etching rates and reduced variability in pattern formation compared to fixed flow rate approaches.
Implementation Method 1
The processing gas is converted to a plasma by a RF (radio frequency) electric field or the like
Implementation Method 2
The processing gas is converted to a plasma by a RF (radio frequency) electric field
Data Source
AI summary
A semiconductor device manufacturing method includes a plasma etching step for etching an etching target film formed on a substrate accommodated in a processing chamber. In the plasma etching step, a processing gas including a gaseous mixture containing predetermined gases is supplied into the processing chamber, and a cycle including a first step in which a flow rate of at least one of the predetermined gases is set to a first value during a first time period and a second step in which the flow rate thereof is set to a second value that is different from the first value during a second time period is repeated consecutively at least three times without removing a plasma. The first time period and the second time period are set to about 1 to 15 seconds.