Oxygen-Adjusted Plasma Etch for Pitch Doubling Depth Control
Solution Overview
Problem
Controlling the etch rate difference between different regions on a substrate during the etching process in semiconductor manufacturing, particularly in pitch doubling techniques, is a challenge as it affects the formation of uniform recessed features essential for semiconductor devices.
Innovation Solution
A method using Self-aligned Double Patterning (SADP) with a plasma etch process that employs an etching gas containing O2 to control the depth of recessed features, where the relative amount of O2 in the gas is selectively adjusted to achieve uniformity between first and second recessed features formed below and between mandrels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a plasma etch process is used to transfer the spacer pattern into the substrate, then the pattern transfer efficiency is improved, but the etch rate difference between different regions causes non-uniform recessed features
Solution Approach 1:
The patent modifies the chemical composition parameters of the etching gas by adding O2 to the standard CF4-based plasma etch gas. This parameter change alters the etching chemistry to reduce the etch rate difference between regions with and without mandrels, thereby achieving more uniform recessed feature depths while maintaining efficient pattern transfer.
2Productivity
If the etch rate is increased to improve productivity, then the manufacturing time is reduced, but the depth control precision between first and second recessed features deteriorates
Solution Approach 1:
By adjusting the O2 concentration parameter in the etching gas mixture, the patent achieves a balanced etching process that maintains high productivity while improving depth control precision. The O2 addition modifies the plasma chemistry to provide more uniform etching rates across different substrate regions, enabling better depth uniformity even at higher etching speeds.
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 effectively controls the etch rate, enabling the formation of recessed features with the same or substantially the same depth, which is crucial for successful double patterning in semiconductor manufacturing, thereby enhancing feature density and device performance.
Implementation Method 1
transferred the pattern defined by the spacers into the substrate using a plasma etch process that etches the plurality of mandrels and the substrate
Implementation Method 2
the plasma etch process utilizes an etching gas containing O2 gas, and the relative amount of O2 gas in the etching gas is selected to control the depth of the first recessed features
Data Source
AI summary
Embodiments of the invention describe a method for controlling etching in pitch doubling. According to one embodiment, the method includes receiving a substrate having a pattern thereon defined by spacers formed on sidewalls of a plurality mandrels, and transferring the pattern defined by the spacers into the substrate using a plasma etch process that etches the mandrels and the substrate, the transferring forming first recessed features in the substrate below the mandrels and second recessed features in the substrate between the mandrels, where the plasma etch process utilizes an etching gas containing O2 gas, and the relative amount of O2 gas in the etching gas is selected to control the depth of the first recessed features relative to the depth of second recessed features. According to another embodiment, the substrate contains a mask layer thereon and a pattern on the mask layer.