Hydrogen-Free Plasma Etching for Selective Groove Processing
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Solution Overview
Problem
In semiconductor manufacturing, forming fine wiring patterns requires etching techniques that maintain pattern shape integrity while allowing for different etching rates across layers, which can complicate the process and require complex layer lamination.
Innovation Solution
An etching method using a plasma processing apparatus that supplies a first gas without hydrogen atoms and a second gas containing silicon and fluorine atoms, generating plasma to selectively remove etching target film portions covering groove surfaces, while maintaining film formation on pattern-defined surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If carbon-based etching target film is formed on side surface to suppress side surface etching, then side surface etching is suppressed, but complicated processes are required to achieve different etching rates for different layers
Solution Approach 1:
The invention changes the chemical composition parameters of the etching gases. By using CF4 gas instead of traditional carbon-based films, and combining it with NF3 gas, the method achieves selective etching through gas composition control rather than complex physical film deposition processes. This parameter change simplifies the overall process while maintaining the ability to suppress side surface etching and achieve differential etching rates.
Solution Approach 2:
The invention uses a composite gas system combining CF4 (containing fluorine for etching) and NF3 (containing fluorine with different reactivity). This composite approach allows the gas mixture to perform multiple functions simultaneously: etching the main surface, suppressing side surface etching, and enabling different etching rates for different layers through controlled gas flow ratios and plasma conditions, thereby simplifying the process complexity.
2Manufacturing precision
If sufficient difference in etching rate between layers is required to maintain pattern shape, then pattern shape is maintained, but complicated processes are required for selective pattern formation
Solution Approach 1:
The invention controls the flow rates and concentrations of CF4 and NF3 gases to achieve different etching rates for different layers. By adjusting gas parameters (flow rate, pressure, temperature) and plasma power settings, the method maintains precise pattern shapes while avoiding complicated multi-step processes. The differential etching is achieved through parameter optimization rather than process complexity.
3Productivity
If traditional hydrogen-containing gases are used for plasma etching, then etching performance is achieved, but hydrogen atoms cause unwanted side reactions and reduce selectivity
Solution Approach 1:
The invention changes the chemical composition of the etching gas from hydrogen-containing gases (like CH4 or C2H2) to hydrogen-free fluorocarbon gases (CF4 and NF3). This parameter change eliminates hydrogen-related side reactions while maintaining effective etching performance through fluorine chemistry. The CF4 provides fluorine radicals for etching, and NF3 enhances selectivity by suppressing polymer deposition, achieving both high productivity and reduced harmful side reactions.
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 allows for the selective removal of etching target film portions on groove surfaces and formation of films on pattern-defined surfaces, enabling easy layer lamination corresponding to the pattern shape while maintaining pattern integrity.
Implementation Method 1
supplying a second gas and high frequency power for plasma generation into the processing chamber to generate in the processing chamber a plasma of a gas including the second gas
Implementation Method 2
supplying a second gas and high frequency power for plasma generation into the processing chamber
Implementation Method 3
The first gas contains an oxidizing agent that does not include a hydrogen atom
Implementation Method 4
The second gas contains a compound that includes one or more silicon atoms and one or more fluorine atoms and does not include a hydrogen atom. The etching target film is made of a material that is dry etched by using fluorine
Data Source
AI summary
An etching method for a target object. The target object includes a main surface, grooves formed in the main surface, and an etching target film covering the main surface and surfaces of the grooves. The method includes supplying a first gas into a processing chamber, and supplying a second gas and a high frequency power to generate a plasma of a gas including the second gas in the processing chamber. The first gas contains an oxidizing agent that does not include a hydrogen atom. The second gas contains a compound that includes one or more silicon atoms and one or more fluorine atoms and does not include a hydrogen atom. The etching target film is made of a material that is dry etched by using fluorine, and portions of the etching target film covering the surfaces of the grooves are selectively removed.