IGZO Thermal ALE for Uniform Etching Without Composition Drift
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Solution Overview
Problem
Conventional etching techniques struggle to etch indium gallium zinc oxide (IGZO) within desirable nonuniformity tolerances without damaging or altering the composition of IGZO material and affecting other materials on the wafer, leading to non-uniformity, residue buildup, and composition changes.
Innovation Solution
Utilizing isotropic thermal atomic layer etching (ALE) with a first chemical species containing fluorine to modify IGZO into indium gallium zinc oxyfluoride, followed by a second chemical species to form volatile molecules that desorb, allowing precise etching without altering IGZO composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching techniques are used on IGZO, then etching speed may be achieved, but etching uniformity deteriorates and material composition is altered
Solution Approach 1:
The etching process is divided into two distinct sequential steps: (1) a modification step where a first process gas reacts with the IGZO surface to form a modified layer, and (2) a removal step where a second process gas selectively removes the modified layer. This segmentation allows each step to be optimized independently, achieving uniform etching while preserving the bulk IGZO composition.
Solution Approach 2:
The modification step creates an intermediate modified layer on the IGZO surface that is selectively removable by the second process gas. This intermediary layer acts as a mediator between the IGZO material and the removal chemistry, enabling precise control over etching uniformity without affecting the underlying IGZO composition.
2Productivity
If conventional etching techniques are used on IGZO, then material removal is achieved, but residue buildup occurs causing defects
Solution Approach 1:
The modified layer serves as an intermediary that facilitates complete and clean removal of IGZO material. The specific chemistry of the modification step creates a layer that is highly reactive to the removal gas, ensuring thorough material removal without leaving residues that would compromise wafer quality.
Solution Approach 2:
The process utilizes specific parameter combinations including temperature control (100-400°C), pressure conditions (1-760 Torr), and carefully selected gas chemistries to optimize both material removal efficiency and cleanliness. These parameter changes enable high productivity while maintaining excellent wafer quality without defects.
3Manufacturing precision
If conventional etching techniques are used on IGZO, then selective etching is attempted, but selectivity is insufficient to prevent damage to other materials
Solution Approach 1:
The modified layer acts as a selective intermediary that enables highly specific etching of IGZO while leaving other materials unaffected. The first process gas modifies only the IGZO surface through specific chemical reactions, and the second process gas removes only this modified IGZO layer, providing excellent selectivity and preventing damage to adjacent materials.
Solution Approach 2:
The modification step creates a localized chemical change only at the IGZO surface, giving it different properties (the modified layer) that make it selectively removable. This local quality change ensures that only the intended IGZO material is etched with high precision, while other materials on the wafer remain completely unaffected.
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
Achieves precise etching of IGZO with minimal impact on its composition and other materials, ensuring uniformity and preventing residue buildup, thus maintaining material properties and reducing defects.
Implementation Method 1
thermal atomic layer etching (ALE) with a process involving fluorine-based modification and alkyl aluminum halide removal molecules to selectively etch IGZO
Implementation Method 2
thermal atomic layer etching (ALE) with a process involving fluorine-based modification and alkyl aluminum halide removal molecules to selectively etch IGZO
Data Source
AI summary
Indium gallium zinc oxide can be etched by providing a wafer having a layer of indium gallium zinc oxide to a processing chamber, heating the wafer to a first temperature, flowing a first chemical species comprising a fluoride to create a layer of indium gallium zinc oxyfluoride, and removing the layer of indium gallium zinc oxyfluoride by flowing a second chemical species comprising an alkyl aluminum halide, an aluminum alkalide, an organoaluminium compound, a diketone, silicon halide, silane, halogenated silane, or alkyl silicon halide.