Polysilicon Recess Etching via IPA Pre-treatment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing substrate processing methods using a mixed solution of ammonia water and hydrogen peroxide face issues with bubble clogging at the entrance of recess portions, leading to incomplete etching and residue retention, especially on hydrophobic surfaces.
Innovation Solution
A method involving a natural oxidation film removal step followed by IPA and ammonia water supply, where IPA spreads on the substrate surface to inhibit gas production and facilitate uniform ammonia water distribution, reducing bubble formation and allowing effective etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a mixed solution of ammonia water and hydrogen peroxide is used to etch unwanted matters in hole portions, then the etching capability is improved, but bubble clogging occurs at the entrance of hole portions causing incomplete etching
Solution Approach 1:
The patent applies preliminary action by first supplying IPA to the substrate before supplying the ammonia water-based etching solution. The IPA pre-treatment modifies the surface properties of the substrate, preventing excessive bubble formation when the etching solution is subsequently applied. This sequential approach ensures that the etching process proceeds without bubble clogging, maintaining both high etching capability and complete coverage of hole portions.
Solution Approach 2:
The patent introduces IPA as an intermediary substance between the substrate and the ammonia water-based etching solution. The IPA acts as a mediator that modifies the interaction between the etching solution and the substrate surface, controlling bubble generation and preventing clogging at the entrance of hole portions. This intermediary approach allows the etching process to proceed effectively without the harmful bubble accumulation effect.
2Manufacturing precision
If the side wall and bottom portion of the hole portion are hydrophobic, then the mixed solution is difficult to be uniformly supplied, but using hydrophilic treatment would improve uniformity
Solution Approach 1:
The patent applies preliminary action by performing IPA-based surface treatment before applying the etching solution. This pre-treatment modifies the surface energy characteristics of the substrate, creating conditions that facilitate uniform distribution of the subsequent ammonia water-based etching solution across hydrophobic surfaces including side walls and bottom portions of hole structures.
3Productivity
If hydrogen peroxide is used in the mixed solution, then oxidation etching is enhanced, but a great amount of gas is produced forming large bubbles that clog the hole entrance
Solution Approach 1:
The patent introduces IPA as an intermediary substance that controls the interaction between hydrogen peroxide and the substrate surface. The IPA layer moderates the oxidation reaction, maintaining high etching efficiency while controlling gas evolution rates to prevent excessive bubble formation and clogging at the hole entrance.
Solution Approach 2:
The patent applies parameter changes by modifying the chemical environment through IPA treatment before applying the hydrogen peroxide-based etching solution. This parameter modification controls the reaction kinetics, maintaining effective oxidation etching while regulating gas production to prevent bubble clogging.
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 approach reduces bubble clogging and ensures uniform ammonia water supply, enhancing the etching process and minimizing residue on the substrate surfaces.
Implementation Method 1
since IPA includes an isopropyl group, when IPA is supplied to the substrate, IPA spreads over the thin film of the group 14 element
Implementation Method 2
A surface of the thin film of the group 14 element is a hydrophobic surface that is not covered with the natural oxidation film
Implementation Method 3
an ammonia water supplying step of supplying ammonia water to the substrate and etching the thin film of the group 14 element after the IPA comes into contact with the thin film of the group 14 element
Implementation Method 4
When the hydrogen peroxide water contained in the mixed solution reacts with the unwanted matters in the hole portion, a great amount of gas is produced from hydrogen peroxide and a large number of bubbles are formed in the hole portion
Data Source
AI summary
The natural oxidation film of polysilicon, which is exposed at a side surface of a recess portion 83 provided in a substrate W, is removed and a thin film 84 of polysilicon is exposed at the side surface of the recess portion 83. Liquid IPA is brought into contact with the thin film 84 of polysilicon after the natural oxidation film of polysilicon is removed. Diluted ammonia water is supplied to the substrate W and the thin film 84 of polysilicon is etched after IPA comes into contact with the thin film 84 of polysilicon.