Substrate Etching Heat Treatment for Reaction Product Removal
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Solution Overview
Problem
The deposition of reaction products on the surface and side walls of etching target films during low-temperature etching in semiconductor wafers with stacked silicon oxide and silicon nitride layers is a challenge, leading to potential damage and reduced yield.
Innovation Solution
A substrate processing method involving etching with plasma and subsequent heat treatment at a predetermined temperature, using a mask and underlying layer containing a transition metal, to remove reaction products without exposing the substrate to the atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If low-temperature etching is used to form high aspect ratio holes, then etching capability is improved, but reaction products deposit on the surface and side walls of the etching target film
Solution Approach 1:
The patent changes the temperature parameter from low-temperature etching to mid-temperature etching (room temperature or higher), which fundamentally alters the etching chemistry to reduce reaction product deposition while maintaining etching capability. This parameter change resolves the contradiction by finding an optimal temperature window that balances etching performance with deposition control.
Solution Approach 2:
The patent converts the harmful reaction products (ammonium fluorosilicate and CF polymer) into removable byproducts by adjusting the etching temperature and gas composition. The modified etching process generates reaction products that can be effectively removed by subsequent cleaning steps, transforming the deposition problem into a manageable cleaning task.
2Object-generated harmful factors
If heat treatment is performed to remove reaction products, then deposition is reduced, but substrate must be exposed to atmosphere
Solution Approach 1:
The patent performs heat treatment in an inert atmosphere (nitrogen or other inert gas) rather than exposing the substrate to air. This inert environment prevents oxidation and contamination of the substrate while still allowing the heat treatment to effectively remove reaction products. The inert atmosphere acts as a protective medium that enables cleaning without atmospheric exposure.
Solution Approach 2:
The patent introduces an intermediary inert gas atmosphere that mediates between the heat treatment process and the substrate. This intermediary environment allows thermal energy to remove reaction products while blocking harmful interactions with atmospheric components. The inert gas serves as a buffer that enables the heat treatment function without the harmful side effects of atmospheric exposure.
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
Effectively removes reaction products like ammonium fluorosilicate and CF polymer without atmospheric exposure, preventing damage to the stacked film and improving yield by maintaining the substrate in a controlled environment.
Implementation Method 1
etching the etching target film through the mask using plasma
Implementation Method 2
performing heat treatment on the substrate at a predetermined temperature after the etching
Data Source
AI summary
A substrate processing method includes providing a substrate formed with a stacked film including at least an etching target film, an underlying layer disposed below the etching target film, and a mask disposed above the etching target film; etching the etching target film through the mask using plasma; and performing heat treatment on the substrate at a predetermined temperature after the etching. At least one of the mask and the underlying layer contains a transition metal.