Semiconductor Surface Passivation for Etch Precision
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges in controlling ion energy, ion flux, and radical flux independently, leading to trade-offs between selectivity, profile, and uniformity in plasma etch processes, particularly in the transition to three-dimensional device fabrication where precision material etch is critical.
Innovation Solution
The method involves passivating target surfaces of semiconductor device structures by exposing them to a gas-phase composition with a processing pressure of 100 mTorr or higher and a radical-to-ion content ratio exceeding 10-to-1, forming a protection layer to reduce side wall etch during etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etch processes are used, then etching can be performed, but side wall etch occurs and device structure integrity deteriorates
Solution Approach 1:
A protection layer is formed on the device structure surfaces before the etching process begins. This preliminary action of coating the surfaces with a protective material prevents side wall etch during the subsequent etching step, thereby improving etch precision while protecting device structure integrity
Solution Approach 2:
The protection layer acts as an intermediary between the etchant and the device structure surfaces. This intermediate layer allows the etching process to proceed while preventing direct contact between the etchant and the device structure sidewalls, thus eliminating side wall etch without compromising etching effectiveness
2Productivity
If ion flux is increased to improve etch rate, then productivity increases, but selectivity and profile control deteriorate
Solution Approach 1:
The process changes the plasma composition parameters to achieve a radical-to-ion content ratio exceeding 10-to-1. This parameter change allows high etch rates to be maintained while improving profile control and selectivity, as radicals provide the etching chemistry while ions provide directional control with reduced damage
3Manufacturing precision
If processing pressure is increased to reduce ARDE, then uniformity improves, but ion energy control becomes more difficult
Solution Approach 1:
The process operates at elevated pressures (equal to or greater than 100 mTorr) and simultaneously adjusts the plasma composition to achieve high radical-to-ion ratios. This combined parameter change reduces aspect ratio dependent etching and improves uniformity while the high radical content compensates for reduced ion directionality, maintaining effective etching control
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 enhances the precision and control of etching processes, reducing side wall etch and maintaining the integrity of device structures, particularly beneficial for forming three-dimensional semiconductor devices.
Implementation Method 1
passivating target surfaces of the device structure by exposing the device structure to a gas-phase composition at a processing pressure equal to or greater than 100 mTorr to form a protection layer on the target surfaces
Implementation Method 2
exposing the device structure to a gas-phase composition at a processing pressure equal to or greater than 100 mTorr to form a protection layer on the target surfaces
Data Source
AI summary
Methods and systems for surface modification are described. In an embodiment, a method of etching includes providing a substrate having a device structure, portions of which are identified for modification. Such a method may also include passivating target surfaces of the device structure by exposing the device structure to a gas-phase composition at a processing pressure equal to or greater than 100 mTorr to form a protection layer on the target surfaces. Other embodiments of a method may include providing a substrate having a device structure, portions of which identified for removal. Such methods may further include passivating target surfaces of the device structure by exposing the device structure to a gas-phase composition, wherein the ratio of the radical content to the ion content exceeds 10-to-1.