Silicon Oxide Etching with Two-Pressure HF Processing
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Solution Overview
Problem
Existing etching methods for substrates with multiple oxide films suffer from insufficient reproducibility of etching results when repeated on the same substrate, particularly due to the presence of reaction products that affect subsequent etching processes.
Innovation Solution
A two-step etching process is employed, where the substrate is etched at two different pressures lower than atmospheric pressure, with the first pressure being between 100 and 600 Torr and the second pressure being no greater than 50 Torr, promoting sublimation and removal of reaction products to ensure consistent etching results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If single-pressure etching is used, then the etching process is simple, but the reproducibility of etching results deteriorates when repeated on the same substrate
Solution Approach 1:
The etching process is divided into two distinct pressure stages: a first etching step at a first pressure (e.g., 10-100 Pa) and a second etching step at a second pressure (e.g., 0.1-10 Pa). This segmentation allows each stage to perform a specific function - the first stage for primary etching and the second stage for removing reaction products - thereby improving reproducibility while maintaining process manageability.
Solution Approach 2:
The invention changes the pressure parameter between etching steps to achieve different etching modes. By switching from a higher pressure (first pressure) to a lower pressure (second pressure), the process transitions from a regime that generates reaction products to a regime that removes them via sublimation, ensuring consistent results across multiple etching cycles.
2Productivity
If reaction products remain on the substrate, then the etching process is continuous, but the reproducibility of etching amounts deteriorates
Solution Approach 1:
The invention utilizes the phase transition (sublimation) of reaction products during the second etching step at low pressure. The reaction products generated during the first etching step sublime in the vacuum environment of the second step, effectively removing them from the substrate surface and ensuring reproducible etching amounts in subsequent cycles.
Solution Approach 2:
The second etching step creates a high-vacuum inert environment that prevents further reaction product formation while promoting sublimation of existing products. This inert environment at low pressure ensures that the substrate surface is cleaned of contaminants between etching cycles, maintaining reproducibility.
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
The two-step etching process enhances the reproducibility of etching results by reducing the influence of reaction products, ensuring consistent etching amounts across multiple processing cycles.
Implementation Method 1
the silicon oxide film is selectively etched against another film by supplying a hydrogen fluoride gas into a chamber
Implementation Method 2
in the second etching step, the silicon oxide film is etched while a reaction product generated on the silicon oxide film in the first etching step is sublimated
Data Source
AI summary
In a substrate processing method, a silicon oxide film formed on a substrate is etched. The substrate processing method includes a first etching step and a second etching step. In the first etching step, the silicon oxide film is selectively etched against another film by supplying a hydrogen fluoride gas into a chamber in a state in which a pressure in the chamber is a first pressure lower than the atmospheric pressure. In the second etching step, the silicon oxide film is selectively etched against the another film by supplying the hydrogen fluoride gas into the chamber in a state in which the pressure in the chamber is a second pressure lower than the atmospheric pressure. The second pressure is lower than the first pressure.