Selective Thermal Etching of Semiconductor Substrates
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Solution Overview
Problem
Current semiconductor etching techniques lack precision and selectivity, particularly in thermally-driven processes, which can lead to inadequate control over etching rates and material removal, especially when dealing with substrates containing multiple materials.
Innovation Solution
A method involving a vapor phase gas mixture comprising a halogen source like hydrogen fluoride, an organic solvent or water, an additive, and a carrier gas, applied at low pressures without plasma exposure, to selectively etch target materials on semiconductor substrates, allowing for precise control over etching rates and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma-based etching is used, then etching speed is improved, but selectivity and precision deteriorate due to difficulty in controlling etching rates for different materials
Solution Approach 1:
The patent changes the fundamental parameters of the etching process by using thermal energy instead of plasma, operating at low pressure (0.2-10 Torr), and employing a specific gas mixture composition (halogen source, organic solvent/water, additive, and carrier gas). These parameter changes enable both high etching rates and superior selectivity between different semiconductor materials.
Solution Approach 2:
The invention uses a composite gas mixture comprising multiple components (halogen source, organic solvent or water, additive, and carrier gas) that work synergistically. This composite approach allows the process to achieve both high productivity through rapid etching and high precision through selective material removal, resolving the contradiction between etching speed and selectivity.
2Manufacturing precision
If conventional thermal etching is used, then selectivity is improved, but etching rate control and precision deteriorate
Solution Approach 1:
The patent transforms conventional thermal etching by introducing specific parameter changes: operating at low pressure (0.2-10 Torr), using a multi-component gas mixture, and controlling thermal energy input. These changes enhance both selectivity and etching rate control, allowing precise material removal while maintaining high productivity.
Solution Approach 2:
The organic solvent or water acts as an intermediary in the gas mixture, mediating between the halogen source and the substrate. This intermediary component enables better control over the etching reaction, improving both selectivity and rate control while maintaining high productivity.
3Productivity
If high pressure etching is used, then material removal efficiency is improved, but precision and selectivity deteriorate due to loss of control over etching rates
Solution Approach 1:
The patent employs low pressure (0.2-10 Torr) as a key parameter change that enables precise control over the etching process. This low-pressure environment, combined with the specific gas mixture composition, maintains high material removal efficiency while achieving superior precision and selectivity, resolving the contradiction between removal efficiency and 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 achieves high precision and selectivity in etching, significantly improving control over etching rates and material removal, particularly between different materials on the substrate, such as silicon oxide and silicon nitride, enhancing the accuracy and efficiency of semiconductor processing.
Implementation Method 1
providing thermal energy to the reaction chamber to drive a reaction that partially or wholly etches the target material from the substrate
Implementation Method 2
providing a gas mixture in the reaction chamber and exposing the substrate to the gas mixture while a pressure in the reaction chamber is between about 0.2-10 Torr, where the gas mixture is vapor phase
Implementation Method 3
the gas mixture is vapor phase and includes: (i) a halogen source such as hydrogen fluoride (HF)
Data Source
AI summary
Various embodiments described herein relate to methods and apparatus for etching a semiconductor substrate to remove a target material from a surface of the substrate. Generally, the techniques described herein are thermal techniques that do not rely on the use of plasma. In a number of embodiments, a particular gas mixture is provided to the reaction chamber to react with the target material. The gas mixture may include a combination of a halogen source such as hydrogen fluoride (HF), an organic solvent and/or water, an additive, and a carrier gas. A number of different materials may be used for the organic solvent and/or for the additive.