Multi-Layer Mask Critical Dimension Reduction via Dry Plasma Etching
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Solution Overview
Problem
Conventional plasma etch processes face challenges in producing finer features in semiconductor substrates due to limitations in the critical dimension reduction during the transfer of patterns from a lithographic layer to underlying mask layers using multi-layer masks.
Innovation Solution
A method involving a multi-layer mask with a lithographic layer overlying a second mask layer, where a dry plasma etching process is used to transfer the feature pattern, adjusting the ratio of fluorocarbon and hydrofluorocarbon gases and etch time to reduce the critical dimension from the lithographic layer to the second mask layer, and potentially extending the etch time to achieve finer feature sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etch processes are used to transfer patterns from lithographic layer to underlying mask layers, then the pattern transfer is achieved, but the critical dimension reduction is limited and finer features cannot be produced
Solution Approach 1:
The patent applies parameter changes by adjusting the ratio of fluorocarbon to hydrofluorocarbon gases and modifying etch time to control the deposition condition on sidewalls. This enables critical dimension reduction from the lithographic layer to the second mask layer, allowing formation of finer features than conventional processes achieve
Solution Approach 2:
The patent employs preliminary action through sidewall deposition during the pattern transfer process. By establishing a deposition condition that causes material deposition on sidewalls as the feature pattern is transferred, the critical dimension is reduced in advance before the final pattern is formed in the second mask layer
2Manufacturing precision
If the etch time is extended to achieve finer feature sizes, then the critical dimension is reduced, but the process time increases
Solution Approach 1:
The patent resolves this contradiction by changing multiple parameters simultaneously - adjusting both the gas ratio (fluorocarbon to hydrofluorocarbon) and etch time. This coordinated parameter adjustment enables critical dimension reduction while managing process time, as the deposition condition is established through the gas ratio which affects etch rate and sidewall protection
3Manufacturing precision
If a multi-layer mask is used with deposition condition on sidewalls, then critical dimension reduction is achieved, but the process complexity increases
Solution Approach 1:
The patent manages process complexity by controlling it through parameter adjustments rather than adding process steps. By adjusting the gas ratio and etch time to establish a deposition condition, the patent achieves critical dimension reduction using the existing multi-layer mask structure without requiring additional masking layers or process steps
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 method effectively reduces the critical dimension of features in the second mask layer, enabling the formation of even finer patterns, which can then be transferred to underlying layers, enhancing the precision of semiconductor fabrication.
Implementation Method 1
formation of plasma when a portion of the gas species present are ionized following a collision with an energetic electron
Implementation Method 2
the heated electrons serve to dissociate some species of the gas mixture and create a reactive mixture of chemical constituents
Implementation Method 3
an etching chemistry is formed that selectively etches the underlying layer while minimally etching the protective layer
Implementation Method 4
a deposition condition on the sidewalls of the feature pattern as the feature pattern is transferred to the second mask layer
Data Source
AI summary
A method of dry developing a multi-layer mask on a substrate is described. The method comprises forming the multi-layer mask on the substrate, wherein the multi-layer mask comprises a lithographic layer overlying a second mask layer. A feature pattern is then formed in the lithographic layer using a lithographic process, wherein the feature pattern comprises a first critical dimension (CD). Thereafter, the feature pattern is transferred from the lithographic layer to the second mask layer using a dry plasma etching process, wherein the dry plasma etching process comprises introducing a process gas, forming plasma from the process gas, and exposing the substrate to the plasma. During the pattern transfer, the first CD in the lithographic layer is reduced to a second CD in the silicon-containing layer.