Thermal Field Etching of Silicon Oxide Films
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Solution Overview
Problem
Current methods for etching native oxide films on silicon surfaces, such as the COR method, result in increased contact resistance due to carbon implantation and silicon damage, requiring additional etching processes to remove damaged layers, while plasma-based methods fail to control etching rates and damage the substrate.
Innovation Solution
A method involving the supply of halogen-containing gases like F2, XeF2, or ClF3, combined with basic gases like HF and NH3, to chemically react with the silicon oxide film and etch the silicon surface, forming a condensation layer that is then heated and removed, reducing contact resistance and eliminating the need for additional etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma-based etching method is used to remove native oxide film, then etching rate is improved, but substrate damage occurs and etching amount cannot be controlled
Solution Approach 1:
The patent changes the etching mechanism from plasma-based to thermal field-based etching. By controlling temperature parameters (heating to 50-200°C) and using thermal energy instead of plasma energy, the method achieves controlled etching of the native oxide film without damaging the underlying silicon substrate. This parameter change resolves the contradiction by maintaining high etching effectiveness while eliminating substrate damage.
2Object-affected harmful factors
If COR method is used to etch native oxide film, then substrate damage is reduced, but contact resistance increases
Solution Approach 1:
The patent applies preliminary cleaning action using the thermal field etching method before contact hole formation. By removing the native oxide film and carbon-containing layers in advance through controlled thermal etching, the silicon surface is prepared in a clean state that prevents subsequent contact resistance issues. This preliminary action resolves the contradiction by eliminating both substrate damage and future contact resistance problems.
3Reliability
If additional etching process is added to remove damaged layers, then contact resistance is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent extracts the damage-removal function from the etching process itself. By using thermal field etching that selectively removes only the native oxide film and carbon-containing layers without damaging the silicon substrate, the method eliminates the need for separate damage removal processes. This extraction resolves the contradiction by achieving low contact resistance through a single optimized etching step rather than multiple processes.
4Reliability
If wet etching method is used to remove native oxide film, then contact resistance is reduced, but manufacturing precision decreases
Solution Approach 1:
The patent substitutes wet chemical etching with a thermal field-based etching mechanism. By using controlled thermal energy to etch the native oxide film, the method achieves both the contact resistance reduction benefits of wet etching and the precision control benefits of dry processes. The thermal field allows precise control of etching depth and rate, resolving the contradiction between contact resistance improvement and manufacturing precision.
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 effectively reduces contact resistance by etching the native oxide film and silicon surface without damaging the substrate, allowing for controlled etching and improved manufacturing throughput by eliminating the need for additional etching steps.
Implementation Method 1
etching the silicon oxide film by supplying a halogen-containing gas and a basic gas to the substrate so that the silicon oxide film is chemically reacted with the halogen-containing gas and the basic gas
Implementation Method 2
heating and vaporizing the condensation layer
Data Source
AI summary
The etching method includes etching the silicon oxide film by supplying a halogen-containing gas and a basic gas to the substrate so that the silicon oxide film is chemically reacted with the halogen-containing gas and the basic gas to generate a condensation layer; etching silicon by supplying a silicon etching gas, which includes at least one selected from the group consisting of an F2 gas, an XeF2 gas, and a ClF3 gas, to the substrate; and after the etching of the silicon oxide film and the etching of the silicon, heating and removing the condensation layer from the substrate.