Copper Etching via Organic Acid Complex Vaporization
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Solution Overview
Problem
Current methods for etching copper in semiconductor devices have low etching rates and are prone to corrosion due to the use of halogen gases, which also corrode substrate processing apparatus components.
Innovation Solution
A substrate processing method using a capacitively coupled plasma etching process with a processing gas mixture of hydrogen and a carbon compound, such as methane or carbon monoxide, to generate carbon radicals and hydrogen plasma, facilitating the formation of organic acid complexes that vaporize easily, thereby increasing the etching rate of copper without using halogen gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If halogen gas or halogen compound gas is used as processing gas for copper etching, then etching rate is improved, but apparatus components corrode due to strong acid generation
Solution Approach 1:
The invention extracts and removes the harmful halogen gas from the processing gas mixture, replacing it with non-corrosive hydrogen gas and oxygen-containing gas. This eliminates the source of strong acid generation while maintaining copper etching capability through alternative chemical mechanisms involving carbon radicals and oxygen.
Solution Approach 2:
The invention changes the chemical composition parameters of the processing gas from halogen-based to hydrogen-based with carbon compound addition. This parameter change transforms the etching mechanism from halogen-driven to a combination of carbon radical-driven organic acid formation and hydrogen plasma etching, achieving both high etching rate and apparatus protection.
2Object-affected harmful factors
If only hydrogen gas is used for copper etching without halogen gas, then apparatus corrosion is prevented, but etching rate becomes low
Solution Approach 1:
The invention creates a composite processing gas system combining hydrogen gas, oxygen-containing gas, and carbon compound gas. This composite approach leverages the complementary strengths of each gas: hydrogen provides plasma and etching capability, oxygen enables copper oxide formation, and carbon compounds generate carbon radicals for organic acid complex formation, achieving both corrosion prevention and high etching rate.
Solution Approach 2:
The invention introduces carbon compound gas as an intermediary that facilitates the formation of organic acid complexes between copper and oxygen. This intermediary mechanism enables efficient copper etching through volatile organic acid complex formation, bridging the gap between corrosion-free hydrogen-based processing and high etching rate requirements.
3Productivity
If carbon compound gas is added to hydrogen gas for plasma generation, then etching rate is improved through organic acid complex formation, but process complexity increases
Solution Approach 1:
The invention employs preliminary action by introducing carbon compound gas before the main etching process to generate carbon radicals in advance. These pre-formed carbon radicals are then available during the etching process to rapidly form organic acid complexes with copper atoms, accelerating the etching rate without requiring complex real-time process adjustments.
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 enhances the etching rate of copper substrates while preventing corrosion in the processing apparatus, allowing for efficient and practical etching without the need for halogen gases.
Implementation Method 1
performing a main etching process that generates plasma from a processing gas produced by adding a gas of a carbon compound to a hydrogen gas, and etches a copper member of the substrate by the plasma
Implementation Method 2
since the organic acid complex is readily vaporized, it is possible to remove a large number of copper atoms from the copper member
Data Source
AI summary
There is provided a substrate processing method capable of increasing an etching rate of a copper member without using a halogen gas. A Cu layer 40 having a smoothened surface 50 is obtained, and then, a processing gas produced by adding a methane gas to a hydrogen gas is introduced into an inner space of a processing chamber 15. Plasma is generated from this processing gas. In the inner space of the processing chamber 15, there exist oxygen radicals 52 generated when an oxide layer 42 is etched, and carbon radicals 53 generated from methane. The oxygen radicals 52 and the carbon radicals 53 are compounded to generate an organic acid, and the organic acid makes a reaction with copper atoms of the Cu layer 40. As a result, a complex of the organic acid having the copper atoms is generated, and the generated organic acid complex is vaporized.