Plasma-Assisted Metal Oxide Etching for High Selectivity
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges in achieving high etch rates and selectivity while maintaining uniformity and selectivity during the removal of metal oxide layers, particularly in plasma etching processes.
Innovation Solution
A plasma-assisted thermal atomic layer etching (ALE) process is employed, utilizing sequential reaction cycles including a surface modification, material removal, and surface cleaning cycles, with controlled pressures and temperatures to enhance etch rates and selectivity, using gases and plasmas to modify and clean the metal oxide surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasma etching is used to remove metal oxide layers, then etch rate can be increased, but selectivity between metal oxide and adjacent materials deteriorates
Solution Approach 1:
The etching process is divided into multiple sequential steps with different chemistries: a first etch step using a metal oxide selective etch chemistry to remove the metal oxide layer with high selectivity, followed by a second etch step using a different chemistry to etch adjacent materials. This segmentation allows each step to optimize for its specific target material, resolving the contradiction between overall etch rate and selectivity.
Solution Approach 2:
A sacrificial layer is introduced as an intermediary element between the metal oxide layer and the substrate. The sacrificial layer is designed to be etched selectively by the first etch chemistry, allowing the metal oxide to be removed indirectly while protecting adjacent materials. This intermediary enables high selectivity while maintaining acceptable overall etch rate through the multi-step process.
2Productivity
If high power plasma is used to increase etch rate, then productivity improves, but surface damage increases
Solution Approach 1:
The etching process uses periodic pulsed plasma application rather than continuous high-power plasma. Plasma is applied in controlled pulses with specific duty cycles, allowing the material to be etched during plasma-on periods while preventing excessive surface damage by allowing relaxation during plasma-off periods. This periodic action resolves the contradiction between etch rate and surface damage.
Solution Approach 2:
The plasma parameters are dynamically changed during the etching process, including power level, gas flow rates, and pressure. By adjusting these parameters in real-time based on process requirements, the system achieves high etch rates when needed while minimizing surface damage through parameter optimization, resolving the contradiction between productivity and harmful effects.
3Ease of manufacture
If conventional etching processes are used, then manufacturing simplicity is maintained, but uniformity across the wafer deteriorates
Solution Approach 1:
The etching process uses dynamic parameter adjustment during the etch cycle, including changing plasma power, gas flows, and pressure throughout the process. This dynamic control allows compensation for spatial variations across the wafer surface, maintaining uniform etching results while using a relatively simple single-chamber reactor design, thus resolving the contradiction between manufacturing simplicity and uniformity.
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 process achieves higher etch rates and improved selectivity between metal oxide and adjacent materials, with enhanced uniformity and reduced surface damage, facilitating precise semiconductor device fabrication.
Implementation Method 1
modifying a surface of a metal oxide layer with a first gas including a plasma
Implementation Method 2
removing a top portion of the metal oxide layer with a ligand exchange reaction performed on the modified surface under a thermal condition
Data Source
AI summary
The present disclosure describes methods and systems for plasma-assisted etching of a metal oxide. The method includes modifying a surface of the metal oxide with a first gas, removing a top portion of the metal oxide by a ligand exchange reaction, and cleaning the surface of the metal oxide with a second gas.