Platinum Etching via CO-H2 Gas Mixture
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Solution Overview
Problem
Existing methods for etching platinum-manganese layers, such as ion milling and halogen gas etching, face challenges including lack of selectivity, damage to mask films, and corrosion of substrate components.
Innovation Solution
A substrate processing method using a gas mixture of carbon monoxide, hydrogen, and a rare gas, with specific flow rate ratios, to etch platinum layers without forming a carbon deposit, allowing for isotropic etching and preventing corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ion milling process is used to etch platinum-manganese layer, then etching capability is improved, but selectivity between mask film and platinum-manganese layer deteriorates and mask film pattern shape is damaged
Solution Approach 1:
The patent changes the etching mechanism from physical (ion milling) to chemical by selecting a processing gas containing chlorine or bromine, which enables selective chemical etching of platinum-manganese while preserving the mask film pattern shape
Solution Approach 2:
The patent replaces the mechanical ion milling process with a chemical etching process using reactive gas, substituting physical bombardment with chemical reactions to achieve both etching capability and pattern fidelity
2Manufacturing precision
If halogen gas is used for chemical etching of platinum-manganese layer, then etching selectivity is improved, but corrosion of magnetic material and apparatus components is accelerated
Solution Approach 1:
The patent modifies the chemical composition of the processing gas by adding oxygen or nitrogen to the chlorine or bromine-based gas, which suppresses the formation of strong acids and reduces corrosion while maintaining etching selectivity
Solution Approach 2:
The patent introduces oxygen or nitrogen as intermediary gases that mediate between the halogen gas and the platinum-manganese layer, preventing direct corrosive interaction while allowing controlled etching through intermediate chemical reactions
3Productivity
If carbon monoxide gas is used for etching, then carbon layer is deposited on exposed surfaces, but this carbon layer can be ashed by hydrogen plasma to enable effective platinum removal
Solution Approach 1:
The patent combines carbon monoxide etching with hydrogen plasma ashing in a continuous or sequential process, where the carbon layer deposited during etching is immediately removed by ashing, maintaining continuous effective etching action without accumulation of unwanted deposits
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
Enables effective etching of platinum layers without halogen gases, reducing corrosion and maintaining pattern shape integrity, with the ability to vaporize organic complexes formed, facilitating efficient removal of platinum.
Implementation Method 1
The carbon layer supplied with energy is reacted with oxygen generated from the carbon monoxide gas, so that a carbonyl group is generated. The surplus hydrogen is combined with the carbonyl group by the energy supplied to the carbon layer, so that a carboxyl group is generated. This carboxyl group as a ligand is coordinate-bonded with the platinum, so that an organic complex is generated.
Implementation Method 2
The organic complex is easy to be vaporized, and, thus, it is possible to remove the platinum from the layer containing, at least, platinum.
Implementation Method 3
a carbon layer is ashed by hydrogen plasma generated from the hydrogen gas. At this time, cations generated from the rare gas are projected to the carbon layer and supply energy to the carbon layer.
Implementation Method 4
cations generated from the rare gas are projected to the carbon layer and supply energy to the carbon layer
Data Source
AI summary
There is provided a substrate processing method capable of etching a layer containing, at least, platinum without using a halogen gas. When etching the platinum-manganese layer on a wafer W by using a tantalum (Ta) layer 38 having a certain pattern shape, a processing gas containing, at least, a carbon monoxide gas, a hydrogen gas, and a rare gas is used, and a ratio of a gas flow rate of the hydrogen gas to a total gas flow rate of the carbon monoxide gas and the hydrogen gas is in a range of from about 50% to about 75%.