Self-Aligned Patterning with SAC SiN Hardmask
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Solution Overview
Problem
Conventional advanced self-aligned patterning (ASAP) processes for semiconductor devices require extra layers and process steps, particularly in the formation of metallization layers, which increases complexity and cost as technology nodes shrink.
Innovation Solution
Forming mandrels directly on the self-aligned contact silicon nitride (SAC SiN) layer and using a conformal metal oxide as sidewall image transfer spacers, eliminating the need for additional hardmask and memorization layers, and employing atomic layer deposition (ALD) for the metal oxide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ASAP process with multiple layers (TiN HM, SiN memorization layer) is used, then patterning precision is maintained, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and removes the TiN hardmask layer and SiN memorization layer from the conventional ASAP process stack. By eliminating these intermediate layers, the process achieves patterning precision through a simplified structure where the SAC SiN layer directly serves as the etch hardmask, reducing device complexity while maintaining manufacturing precision
Solution Approach 2:
The SAC SiN layer is assigned multiple functions: it serves as both the self-aligned contact layer and the etch hardmask for the ULK layer. This multi-functionality eliminates the need for separate TiN HM and SiN memorization layers, reducing the number of layers while maintaining patterning precision through the inherent properties of the SAC SiN layer
2Reliability
If conventional ASAP process with extra materials and deposition steps is used, then etch hardmask performance is achieved, but productivity decreases
Solution Approach 1:
The patent removes the TiN hardmask deposition step and SiN memorization layer formation from the process flow. By extracting these unnecessary steps, the manufacturing efficiency improves significantly while the etch hardmask performance is maintained through the optimized SAC SiN layer configuration that directly provides the required etch resistance
Solution Approach 2:
The SAC SiN layer is formed with optimized thickness (5-20 nm) and properties in advance to serve dual purposes as both contact layer and etch hardmask. This preliminary optimization eliminates the need for subsequent TiN deposition and SiN layer formation, improving productivity while ensuring adequate etch hardmask performance for the ULK layer
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 reduces the number of layers and process steps, simplifying the ASAP process while maintaining performance, and is applicable for the 7 nanometer technology node and beyond, enhancing manufacturing efficiency and cost-effectiveness.
Implementation Method 1
employing atomic layer deposition (ALD) for the metal oxide layer
Data Source
AI summary
A method of forming a metallization layer by ASAP is provided. Embodiments include forming an ULK layer; forming a SAC SiN layer over the ULK layer; forming mandrels directly on the SAC SiN layer; cutting the mandrels; selectively etching the SAC SiN layer across the cut mandrels, forming first trenches; filling the first trenches with a metal oxide; forming a conformal metal oxide layer over the cut mandrels, the metal oxide, and the SAC SiN layer; removing horizontal portions of the conformal metal oxide layer over the cut mandrels and the SAC SiN layer; removing the cut mandrels; removing exposed portions of the SAC SiN layer and etching the underlying ULK layer, forming second trenches; and stripping a remainder of the metal oxide, conformal metal oxide layer, and SAC SiN layer.