Hard Mask Sidewall Reinforcement via Silicon Sputtering
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Solution Overview
Problem
In etching silicon-based layers through a hard mask, the sidewalls of the hard mask can erode, leading to an increase in the space CD of the features being etched, which is undesirable in semiconductor device fabrication.
Innovation Solution
A method involving silicon sputtering to deposit additional sidewalls on the patterned hard mask using argon ions in a plasma processing chamber, with a bias voltage greater than 200 volts to sputter silicon from the silicon-based etch layer onto the hard mask sidewalls, and subsequent etching through the patterned hard mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching is performed through a hard mask, then features are etched into the silicon based etch layer, but the sidewalls of the hard mask erode causing the space CD to increase and bar CD to decrease
Solution Approach 1:
The patent applies preliminary action by depositing additional sidewall material on the hard mask before the etching process. This pre-deposition of silicon-based material reinforces the hard mask sidewalls in advance, preventing erosion during etching and maintaining precise feature dimensions throughout the etching process.
Solution Approach 2:
The patent employs composite materials by combining the hard mask with additional silicon-based sidewall material. This creates a composite structure where the hard mask and deposited silicon work together, with the silicon providing enhanced sidewall stability and preventing erosion during the etching process.
2Manufacturing precision
If argon ions are used for sputtering, then silicon is deposited onto hard mask sidewalls to form additional sidewalls, but the process requires high bias voltage greater than 200 volts
Solution Approach 1:
The patent applies parameter changes by optimizing the sputtering process parameters, specifically using argon ions with bias voltage greater than 200 volts. This parameter selection enables effective silicon deposition on sidewalls while controlling the deposition rate and film quality, achieving the desired sidewall reinforcement.
3Manufacturing precision
If additional sidewalls are formed on the hard mask, then the hard mask trimming is reduced and feature size is maintained, but the process complexity increases with additional sputtering steps
Solution Approach 1:
The patent applies merging by combining the sidewall deposition and etching processes into an integrated flow. The additional silicon sidewalls are deposited and then immediately used in the subsequent etching process, merging the preparatory and main processing steps into a cohesive manufacturing sequence that maintains feature size while managing process 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 approach prevents the increase in etch feature width, maintaining precise feature dimensions by forming additional sidewalls that act as an effective etch mask, reducing the trimming of the hard mask and maintaining the original feature size.
Implementation Method 1
A silicon sputtering is provided to sputter silicon from the silicon based etch layer onto sidewalls of the patterned hard mask to form additional sidewalls on the patterned hard mask
Implementation Method 2
forming the sputtering gas into a plasma to generate argon ions
Implementation Method 3
forming the sputtering gas into a plasma to generate argon ions
Implementation Method 4
providing a bias greater than 200 volts that accelerates the argon ions in the plasma to the silicon based etch layer with sufficient energy to sputter silicon
Data Source
AI summary
A method for etching features into a silicon based etch layer through a patterned hard mask in a plasma processing chamber is provided. A silicon sputtering is provided to sputter silicon from the silicon based etch layer onto sidewalls of the patterned hard mask to form sidewalls on the patterned hard mask. The etch layer is etched through the patterned hard mask.