Plasma Etching Profile Control via Carbon-Containing Gas Mixture
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Solution Overview
Problem
The challenge in semiconductor manufacturing is achieving high controllability over etching profiles while suppressing the generation of etching residues during the dry development process of a triple layer resist, particularly when using O2-based etching gases, which often results in poor vertical etching and residue accumulation on the base layer.
Innovation Solution
A plasma etching method using a gaseous mixture of O2 and a carbon-containing compound gas, with a specific flow rate ratio, is employed to etch the lower organic material film, where the carbon-containing compound gas is preferably CO or CH4, and the method involves a capacitively coupled plasma etching apparatus with controlled high-frequency power applications to the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If O2 based etching gas is used for dry development of lower resist film, then the etching process can be performed, but the etching profile controllability deteriorates and residues accumulate on the base layer
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas from pure O2 to a mixture containing CF4 (5-20%) and CO (80-95%). This parameter change transforms the etching mechanism to produce volatile reaction products that prevent residue formation while maintaining vertical etching profiles through controlled gas chemistry
Solution Approach 2:
The patent uses a composite etching gas system combining CF4 and CO gases. CF4 provides the etching capability through fluorine radicals, while CO acts as a carrier gas that facilitates volatile product formation. This composite gas system resolves the contradiction between etching effectiveness and residue prevention
2Measurement precision
If the thickness of the resist film is reduced to achieve fine patterns, then the resolution improves, but the selectivity of the target layer against the resist film deteriorates
Solution Approach 1:
The patent changes the etching chemistry parameters by introducing carbon-containing gases (CF4 and CO) that create a more selective etching environment. The carbon-based chemistry provides different etching rates for the resist film versus the target layer, maintaining high selectivity even when the resist film thickness is reduced for fine pattern resolution
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 high accuracy in etching profiles and effectively suppresses the generation of etching residues, particularly on wide opening patterns, enhancing the reliability of semiconductor device fabrication.
Implementation Method 1
a plasma etching method for performing an etching on a target object
Implementation Method 2
etching the lower organic material film by using the upper organic material film and the intermediate layer as a mask in a processing chamber of a plasma etching apparatus
Data Source
AI summary
A plasma etching method includes the step of etching a lower organic material film by using an upper organic material film and an intermediate layer as a mask in a processing chamber of a plasma etching apparatus, while using an etching gas made up of a gaseous mixture including an O2 gas and a carbon-containing compound gas which has a carbon atom in a molecule, to thereby transfer a pattern of the intermediate layer to the lower organic material film. A ratio of a flow rate of the carbon-containing compound gas to a total flow rate of the etching gas ranges from about 40 to 99%.