Substrate Etching with Heated Ammonium Fluoride Depth Control
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Solution Overview
Problem
Existing substrate processing methods struggle to accurately control the etching depth due to difficulties in stopping the reaction between process gases and substrates at a desired depth.
Innovation Solution
A substrate processing method involving an etching liquid supply step with ammonium fluoride as the etching agent, a heating step to promote reaction between the etching agent and the substrate, and a rinse liquid supply step to control the etching depth, achieving saturated atomic layer etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If process gas is used for etching, then etching can be performed, but it is difficult to stop the reaction at a desired etching depth
Solution Approach 1:
The patent employs periodic action by controlling the supply and stop cycles of etching liquid to the substrate. The etching liquid is supplied for a predetermined period to achieve saturated atomic layer etching, then stopped to halt the reaction. This periodic supply and stop mechanism enables precise control of etching depth by adjusting the supply time, resolving the contradiction between achieving desired etching depth and stopping the reaction at that depth.
2Productivity
If etching liquid is supplied continuously, then etching proceeds, but time dependency increases making depth control difficult
Solution Approach 1:
The patent applies parameter changes by controlling the supply time of etching liquid as a critical parameter. By adjusting the supply time to a predetermined value, the patent achieves saturated atomic layer etching where the etching amount becomes independent of time. This parameter control transforms the process from time-dependent to saturation-dependent, enabling precise depth control while maintaining productivity.
3Productivity
If heating is applied to promote reaction, then etching efficiency increases, but process complexity increases
Solution Approach 1:
The patent utilizes phase transitions by heating the etching liquid to promote the reaction between the etching agent and substrate. The heating causes phase transition in the reaction products, facilitating the etching process. This approach increases etching efficiency while the heating system is integrated into the existing processing equipment, minimizing additional complexity.
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 method allows for precise control of etching depth by reducing time dependency and achieving saturated atomic layer etching, enabling accurate and efficient processing of substrates.
Implementation Method 1
a heating step of heating the etching liquid on the major surface of the substrate after the etching liquid supply step
Implementation Method 2
a rotating step of rotating the substrate about a center axis that passes a center portion of the major surface of the substrate after stopping the supply of the etching liquid to the major surface of the substrate in the etching liquid supply step and before the heating step
Data Source
AI summary
A substrate processing method processes a substrate having a major surface in which at least one of a silicon oxide layer and a silicon nitride layer is exposed as a processing target layer. The substrate processing method includes an etching liquid supply step of supplying the major surface of the substrate with an etching liquid containing an ammonium fluoride as an etching agent to etch the processing target layer, a heating step of heating the etching liquid on the major surface of the substrate after the etching liquid supply step, and a rinse liquid supply step of supplying the major surface of the substrate with a rinse liquid after the heating step.