Plasma Etching Method for High Aspect Ratio Recesses
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Solution Overview
Problem
Existing methods for forming high aspect ratio recesses in semiconductor device manufacturing face challenges in achieving a high etching rate due to the need for additional steps to remove protective films from the bottom surface of recesses, which slows down the etching process.
Innovation Solution
A plasma processing method involving alternating etching and protective film formation steps, where a first gas (SF6, ClF3, F2) is used for etching and a second gas (hydrocarbon, fluorocarbon, fluorohydrocarbon) is used to form a protective film on the sidewall while suppressing its formation on the bottom surface, utilizing different pressures and bias powers to control ion sputtering and active species distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a protective film is formed on the bottom surface of the recess during etching, then the sidewall is protected, but the etching rate decreases due to the need for additional removal steps
Solution Approach 1:
The patent applies local quality by creating different film formation characteristics in different regions of the recess. By controlling plasma parameters (pressure and bias power), the protective film is formed preferentially on the sidewall while suppressing its formation on the bottom surface. This localized differentiation allows sidewall protection without the penalty of film removal steps, thereby resolving the contradiction between manufacturing precision and productivity.
2Productivity
If the protective film formation is suppressed on the bottom surface, then the etching rate increases, but sidewall protection may be compromised
Solution Approach 1:
The patent employs parameter changes by adjusting plasma processing conditions (pressure and bias power) to control the deposition and sputtering rates of the protective film. By setting pressure to a second value lower than the first value and bias power to a second value higher than the first value during protective film formation, the method creates conditions where ion sputtering removes film from the bottom surface while deposition maintains film on the sidewall, thus achieving both high etching rate and sidewall protection.
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 high aspect ratio recesses at a higher etching rate by preventing protective film formation on the bottom surface and promoting it on the sidewall, thus enhancing depth direction etching while maintaining sidewall protection.
Implementation Method 1
etching an etching target layer of the target object by supplying a first gas containing at least one of SF6, ClF3 and F2 into the processing chamber and generating a plasma of the first gas
Implementation Method 2
the etching target layer of the target object is etched by the plasma of the first gas
Implementation Method 3
forming a protective film on at least a part of the etching target layer by supplying a second gas containing at least one of hydrocarbon, fluorocarbon, and fluorohydrocarbon into the processing chamber and generating a plasma of the second gas
Implementation Method 4
the plasma of the second gas is generated, and the protective film is formed on a part of the etching target layer
Data Source
AI summary
A method includes: etching a target layer of a target object in a processing chamber by generating a plasma of a first gas containing at least one of SF6, ClF3 and F2 supplied into the processing chamber to; and forming a protective film on the target layer by generating a plasma of a second gas containing at least one of hydrocarbon, fluorocarbon, and fluorohydrocarbon supplied into the processing chamber. In the etching, a pressure in the processing chamber is set to a first pressure and a first bias power is applied to a lower electrode. In the forming, the pressure is set to a second pressure lower than the first pressure and a second bias power higher than the first bias power is applied to the lower electrode.