Nanolayer Capping Layer for Hardmask Etch Resistance
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Solution Overview
Problem
Conventional hardmask layers, particularly titanium nitride (TiN) layers, exhibit poor etch resistance, limiting their use in advanced semiconductor manufacturing processes such as trench first metal hardmask schemes and VIA double patterning schemes due to inadequate performance in self-aligned VIA applications.
Innovation Solution
A capping layer composed of nanolayers such as silicon carbide (SiC), cubic boron nitride (c-BN), or turbostatic boron nitride (t-BN) is formed over the hardmask layer, with a total thickness of less than 40 nanometers, enhancing etch resistance and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional TiN hardmask layer is used, then the manufacturing process is simple, but the etch resistance is poor
Solution Approach 1:
The patent applies composite materials by combining TiN hardmask layer with multiple capping layer nanolayers (SiC, SiCN, BN, TiN) to create a composite structure that achieves superior etch resistance. The composite nature of these layers provides both the etch resistance needed for advanced processes and the structural integrity required for merged VIA formation, directly resolving the contradiction between simplicity and etch resistance.
Solution Approach 2:
The capping layer is segmented into multiple nanolayers (1-10 nm thick) of different materials (SiC, SiCN, BN, TiN) rather than using a single thick layer. This segmentation provides enhanced etch resistance through the combined properties of multiple materials while maintaining overall layer thickness below 40 nm, thus improving etch resistance without excessive complexity.
2Reliability
If the hardmask and capping layers are made thicker to improve etch resistance, then etch performance improves, but the total thickness increases beyond acceptable limits
Solution Approach 1:
The patent changes the parameters of the capping layer by using multiple nanolayers with thicknesses between 1-10 nm each, totaling 10-30 nm for the capping layer. This parameter optimization ensures the combined hardmask and capping layer thickness remains below 40 nm while achieving the required etch resistance for merged VIA processes, resolving the contradiction between etch resistance and thickness constraints.
3Reliability
If conventional hardmask layers are used, then current lithography tools can be used, but merged VIAs cannot be formed with sufficient etch resistance
Solution Approach 1:
The composite capping layer structure with multiple nanolayers of SiC, SiCN, BN, and TiN provides the enhanced etch resistance necessary for merged VIA formation. This composite approach allows critical functions like merged VIAs to be used with existing lithography tools while maintaining the structural complexity needed for superior etch performance throughout the via formation process.
Data Source
AI summary
A capping layer is formed over a hardmask layer to increase the etch resistance and overall performance of the hardmask layer. Embodiments include forming a hardmask layer over a substrate and forming a capping layer on the hardmask layer, the capping layer including a stack of at least two nanolayers.