Optically Tuned Hardmask for Multi-Patterning
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Solution Overview
Problem
Current multi-patterning processes for semiconductor fabrication require repeated application and stripping of optically opaque tri-layer stacks, leading to inefficiencies and complexities in achieving precise submicron features due to reflection issues at the resist-hardmask interface, which complicates the formation of submicron interconnects and increases material waste.
Innovation Solution
A thin film with optical properties matched to the resist layer is used as the hardmask, eliminating the need for tri-layer stacks by matching the refractive index and extinction coefficient of the SiOxNyCz:Hw layer to the resist, ensuring minimal reflection and allowing multiple patterning sequences without the need for repeated deposition and stripping of intermediate layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional hardmask layers are used with ultra violet light exposure, then the hardmask can be patterned, but reflections occur at the resist-hardmask interface causing distortion and reduced precision in feature formation
Solution Approach 1:
An optical matching layer is introduced between the resist and hardmask layers. This intermediary layer has optical properties (refractive index and extinction coefficient) that are matched to both the resist and hardmask, eliminating reflections at the interfaces through optical impedance matching, thereby preventing distortion without requiring OPC
Solution Approach 2:
The optical properties (refractive index and extinction coefficient) of the hardmask system are modified by introducing the optical matching layer with specific optical parameters. This parameter change enables the system to achieve optical transparency and eliminate reflections at the resist-hardmask interface, improving feature precision without OPC
2Manufacturing precision
If tri-layer stacks are used to block exposure wavelength and prevent reflections, then feature precision can be maintained, but processing complexity and material waste increase due to repeated deposition and stripping
Solution Approach 1:
The complex tri-layer stack structure is replaced by a simplified single optical matching layer. This extraction of unnecessary layers (the multi-layer anti-reflective coating and memory layer) while retaining the essential function of optical matching reduces processing complexity and material waste while maintaining feature precision
Solution Approach 2:
The optical matching layer performs multiple functions simultaneously: it blocks the exposure wavelength from reaching the hardmask, prevents reflections at the resist-hardmask interface, and serves as the memory layer for pattern storage. This multi-functionality eliminates the need for separate tri-layer components and their repeated deposition/stripping cycles
3Manufacturing precision
If optical proximity correction is applied to compensate for reflections, then some feature precision can be maintained, but additional processing steps and complexity are required
Solution Approach 1:
Optical matching is performed in advance during the hardmask formation process by depositing the optical matching layer with matched optical properties. This preliminary optical optimization eliminates reflections before lithography, making OPC unnecessary and reducing processing complexity while maintaining feature precision
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 enables precise and efficient multi-patterning of hardmask layers with reduced material waste and processing complexity, maintaining feature precision and increasing yield by eliminating the need for complex optical proximity corrections and multiple tri-layer cycles.
Implementation Method 1
matching the refractive index and extinction coefficient of the SiOxNyCz:Hw layer to the resist
Implementation Method 2
eliminating the need for tri-layer stacks by matching the refractive index and extinction coefficient of the SiOxNyCz:Hw layer to the resist, ensuring minimal reflection
Implementation Method 3
sputtering a material comprising silicon from a target disposed in a chamber onto a surface of a substrate
Data Source
AI summary
The embodiments herein provides methods for forming a PVD silicon oxide or silicon rich oxide, or PVD SiN or silicon rich SiN, or SiC or silicon rich SiC, or combination of the preceding including a variation which includes controlled doping of hydrogen into the compounds heretofore referred to as SiOxNyCz:Hw, where w, x, y, and z can vary in concentration from 0% to 100%, is produced as a hardmask with optical properties that are substantially matched to the photo-resists at the exposure wavelength. Thus making the hardmask optically planarized with respect to the photo-resist. This allows for multiple sequences of litho and etches in the hardmask while the photo-resist maintains essentially no optical topography or reflectivity variations.