Silicon Oxide Etching via Periodic HF and Ammonia Gas Pressurization
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Solution Overview
Problem
Conventional methods struggle to effectively remove natural oxide films from deep trenches in field-effect transistor devices due to insufficient supply of etching gases, leading to incomplete removal and increased resistance values.
Innovation Solution
A method involving the alternation of heating the substrate to 60°C or higher, supplying pressurized hydrogen fluoride and ammonia gases, and controlling gas flow to ensure efficient etching of silicon oxide films, including pressurizing the gases in the supply pipe to enhance gas delivery to deep trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to remove natural oxide films, then the process is simple, but the etching is incomplete in deep trenches leading to increased resistance values
Solution Approach 1:
The patent applies periodic action by alternately repeating the etching process (supplying HF and NH3 gases to form reaction products) and the heating process (heating to 60°C or higher to remove reaction products). This cyclic approach ensures thorough removal of natural oxide films from deep trenches by preventing reaction product accumulation that would block further etching, thereby achieving complete etching and reducing resistance values.
2Manufacturing precision
If etching gases are supplied continuously, then the etching process is simple, but the gas supply is insufficient to reach the bottom of deep trenches
Solution Approach 1:
The patent uses periodic action by interrupting the gas supply periodically and alternating it with heating cycles. During the heating phase, gas supply is stopped and the substrate is heated to 60°C or higher to remove accumulated reaction products. This periodic interruption and removal of reaction products prevents gas flow blockage, allowing fresh etching gases to reach the bottom of deep trenches during subsequent etching cycles, thereby improving oxide film removal efficiency.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the substrate temperature parameter during the etching process. The temperature is raised to 60°C or higher during the heating phase to facilitate reaction product removal, and then returned to lower temperatures during the etching phase. This temperature parameter modulation enables effective control of reaction product formation and removal, ensuring sufficient gas penetration to deep trench bottoms.
3Productivity
If the substrate is heated continuously at high temperature, then reaction product removal is efficient, but the etching reaction efficiency decreases
Solution Approach 1:
The patent applies periodic action by alternating between etching cycles (lower temperature for efficient etching) and heating cycles (higher temperature of 60°C or more for efficient reaction product removal). This periodic switching ensures that the substrate spends sufficient time at low temperature for effective etching while also receiving periodic heating treatment to remove accumulated reaction products, thereby maintaining both high etching rate and effective reaction product removal.
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 ensures thorough removal of natural oxide films from both the surface and bottom portions of trenches, improving etching efficiency and reducing resistance values, while also reducing the risk of roughness and throughput issues.
Implementation Method 1
supplying hydrogen fluoride gas and ammonia gas onto the substrate to react with the silicon oxide
Implementation Method 2
heating the substrate on which the silicon oxide is formed to a heating temperature of 60° C. or higher
Implementation Method 3
closing a valve disposed between the substrate and the flow path to pressurize the process gas in the flow path
Data Source
AI summary
A method of etching silicon oxide on a surface of a substrate is provided. The method comprises alternately repeating heating the substrate to a heating temperature of 60° C. or higher, supplying hydrogen fluoride gas and ammonia gas onto the substrate to react with the silicon oxide, and modifying the silicon oxide to obtain a reaction product, and removing at least a portion of the reaction product from the substrate while stopping the supply of the above gases and continuing to heat the substrate at the heating temperature; and when a process gas that is at least one of the hydrogen fluoride gas and the ammonia gas is supplied, while continuing to supply the process gas from an upstream side of a flow path, closing a valve disposed in the flow path to pressurize the process gas in the flow path, and then opening the valve.