IGZO Etching with Methane-Argon Cycling to Avoid Passivation
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Solution Overview
Problem
Conventional etching methods for indium gallium zinc oxide (IGZO) structures face challenges such as non-volatile by-product formation, passivation issues, and inefficiency in high-density pattern etching, especially at tighter pitches, which hinder the unlocking of IGZO's advantages like high carrier mobility and flexibility.
Innovation Solution
A method involving alternating exposure to a methane-based reactant flow and an argon flow, allowing for controlled etching without passivation, using low-pressure flows and potentially zero bias, to remove reactant and IGZO molecules simultaneously, enabling precise etching without the need for oxygen strips and hydrogen, which can dope IGZO structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional halogen-based chemistries are used for etching IGZO, then etching can be performed, but non-volatile by-products are formed
Solution Approach 1:
The patent changes the chemical composition parameters of the etching reactant from halogen-based to hydrocarbon-based (CH4/Ar mixture), which fundamentally alters the etching chemistry to produce volatile by-products instead of non-volatile ones, resolving the contradiction between etching capability and by-product formation
Solution Approach 2:
The patent converts the previously harmful effect of metal-halogen interaction into a beneficial outcome by using hydrocarbon-based chemistry where the carbon-containing reactants produce volatile gaseous by-products that can be easily removed, turning the etching process into one that leaves no harmful residues
2Productivity
If CH4/Ar reactant is used for etching IGZO, then etching can be performed, but passivation occurs acting as an etch stop
Solution Approach 1:
The patent applies periodic alternating action by switching between CH4/Ar reactant flow for etching and O2 plasma flow for removing passivation layers, creating a cyclic process that enables continuous etching despite the formation of passivation layers during the etching phase
Solution Approach 2:
The patent introduces oxygen plasma as an intermediary substance that mediates between the etching process and the passivation problem by selectively removing the passivation layers formed during etching, allowing the etching process to continue without being blocked
3Object-generated harmful factors
If alternating etching steps and oxygen strips are used, then passivation can be removed, but the process becomes complex and time-consuming
Solution Approach 1:
The patent extracts and removes the problematic passivation removal step from the etching process by using a different etching chemistry that does not form passivation layers, thereby simplifying the overall process by eliminating the need for separate oxygen strip steps
Solution Approach 2:
The patent inverts the conventional approach by not trying to prevent passivation formation but instead using a reactant system where passivation is naturally avoided through the use of hydrocarbon-based chemistry combined with oxygen plasma treatment, reversing the traditional problem-solving strategy
4Manufacturing precision
If etching is performed at tighter pitches with thicker IGZO films, then high-density patterns are achieved, but etch stop occurs preventing further etching
Solution Approach 1:
The patent ensures continuity of the etching action by using a reactant system that maintains etching capability throughout the process without encountering etch stops, allowing the etching to proceed continuously and completely through thick IGZO films at tight pitches without interruption
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 achieves accurate, controlled etching of IGZO structures down to the nanometer regime, avoiding passivation and allowing deeper etching of thicker films, with improved wafer uniformity and no etch stop, suitable for high-density patterns without additional processing steps.
Implementation Method 1
exposing the IGZO structure to a reactant flow comprising a methane-based reactant, wherein a reactant layer is formed on the IGZO structure
Implementation Method 2
exposing the reactant layer formed on the IGZO structure to an argon flow, wherein one or more reactant molecules are removed from the reactant layer, wherein the one or more reactant molecules, which are removed from the reactant layer formed on the IGZO structure, are removed together with one or more IGZO molecules
Data Source
Figure 1(a)~1(d)
Figure 2(a)~2(b)
Figure 3(a)~3(d)
AI summary
The present disclosure relates to a method for etching an indium gallium zinc oxide (IGZO) structure. The method comprises exposing the IGZO structure to a reactant flow comprising a hydrocarbon-based reactant. Thereby, a reactant layer is formed on the IGZO structure. Further, the method comprises exposing the reactant layer formed on the IGZO structure to an argon flow. Thereby, one or more reactant molecules are removed from the reactant layer. The one or more reactant molecules, which are removed from the reactant layer formed on the IGZO structure, are removed together with one or more IGZO molecules, thus leading to an etching of the IGZO structure.