Spin-On SiC Cap Layers for Defect-Reduced Self-Aligned Contacts
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Solution Overview
Problem
Conventional self-aligned contact processes using CVD silicon carbide (SiC) for trench contacts face issues with void formation and planarization defects, which are not adequately addressed by existing methods.
Innovation Solution
The use of spin-on silicon carbide (SiC) as a cap layer material for conductors, allowing for improved etch selectivity and reduced defectivity by forming self-aligned contacts through specific etch processes and planarization techniques, replacing traditional deposition methods like CVD or PVD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CVD silicon carbide is used as cap material for trench contacts, then etch selectivity is achieved, but void formation and planarization defects occur
Solution Approach 1:
The patent changes the deposition method parameter from CVD to spin-on coating, which fundamentally alters how the silicon carbide cap layer is formed. This parameter change eliminates the inherent void formation and planarization defects associated with CVD while maintaining the material's etch selectivity properties
Solution Approach 2:
The patent uses spin-on silicon carbide as a cap material that copies the functional properties of CVD silicon carbide (etch selectivity) without replicating its manufacturing defects. The spin-on process creates a defect-free layer that serves the same protective and selective etching functions
2Productivity
If device linewidths are shrunk to meet design criteria, then device density increases, but etch selectivity requirements become more demanding
Solution Approach 1:
By changing the cap material deposition method to spin-on, the patent achieves superior surface uniformity and thickness control, which provides more consistent etch selectivity ratios. This enhanced parameter control is critical for maintaining reliable self-aligned contact formation as device dimensions shrink
3Ease of manufacture
If CVD SiC is deposited and planarized, then cap layers are formed for trench contacts, but defectivity increases and yield decreases
Solution Approach 1:
The patent replaces the mechanical planarization process (CMP) with a spin-on deposition process that inherently produces planar surfaces. This substitution eliminates the need for subsequent planarization steps that cause defects and yield loss, while still achieving the required cap layer formation
Solution Approach 2:
The spin-on process copies the functional outcome of CVD deposition and planarization without replicating the defect formation mechanisms, thereby achieving cap layer formation with significantly improved yield
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 enhances the yield and reduces defects in self-aligned contact formation, providing better etch selectivity and planarization results compared to traditional methods, thus meeting the demands of shrinking device criteria.
Implementation Method 1
forming a second cap layer over the plurality of second conductors, wherein the second cap layer is formed by spin coating a second dielectric material onto the substrate
Implementation Method 2
spin coating a second dielectric material onto the substrate
Data Source
AI summary
Methods and improved process flows are provided herein for forming self-aligned contacts using spin-on silicon carbide (SiC). More specifically, the disclosed methods and process flows form self-aligned contacts by using spin-on SiC as a cap layer for at least one other structure, instead of depositing a SiC layer via plasma vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD), etc. The other structure may be a source and drain contact made through the use of a trench conductor. By utilizing spin-on SiC as a cap layer material, the disclosed methods and process flows avoid problems that typically occur when SiC is deposited, for example by CVD, and subsequently planarized. As such, the disclosed methods and process flows improve upon conventional methods and process flows for forming self-aligned contacts by reducing defectivity and improving yield.