Oligomer Bottom-Up Gap Fill for Selective Metal Deposition
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Solution Overview
Problem
Conventional deposition processes struggle to achieve defect-free filling of gaps in semiconductor manufacturing, especially as device geometries shrink and thermal budgets are reduced, leading to poor selectivity and damage to underlying metal or metal silicide surfaces.
Innovation Solution
A processing method involving the exposure of a semiconductor substrate surface with features to monomers to form an oligomer film, which selectively forms on the bottom and fills a portion of the feature depth, allowing for subsequent selective metal deposition without damaging the underlying surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional PVD processes are used to deposit tungsten seed layer, then sufficient seed layer thickness can be achieved, but the tungsten fill process deposits tungsten on any exposed seed layer resulting in poor selectivity
Solution Approach 1:
The patent introduces an oligomer film as an intermediary protective layer between the tungsten seed layer and the tungsten fill deposition process. This oligomer film selectively protects the bottom surface of the trench, allowing tungsten to be deposited only in protected areas, thereby achieving high selectivity while maintaining sufficient seed layer thickness
Solution Approach 2:
The oligomer film is deposited onto the tungsten seed layer before the tungsten fill deposition process. This preliminary action creates a protective mask that prevents tungsten deposition on exposed seed layer surfaces, enabling selective fill only in protected regions
2Reliability
If polymer film is deposited to achieve selective protection, then surface protection can be achieved, but the height of the polymer film varies with varying critical dimensions (CD) of the feature
Solution Approach 1:
The patent changes the parameters of the deposition process by using oligomerization reactions with controlled monomer exposure and reaction conditions. This allows the oligomer film to achieve uniform height across features with varying CD by controlling the chemical reaction rather than relying on physical deposition thickness
Solution Approach 2:
The patent utilizes phase transition from monomer to oligomer through controlled oligomerization reactions. This chemical phase change enables uniform film formation by allowing the reaction to proceed to completion across different feature geometries, ensuring consistent film height regardless of CD variations
3Productivity
If selective metal deposition is performed without protective film, then direct metal fill can be achieved, but damage occurs to the underlying metal or metal silicide surfaces
Solution Approach 1:
The oligomer film serves as an intermediary protective barrier between the deposition process and the underlying metal or metal silicide surfaces. It allows direct fill capability while preventing surface damage by absorbing or distributing mechanical and thermal stresses during the deposition process
Solution Approach 2:
The oligomer film is deposited beforehand to provide cushioning protection to the underlying surfaces. This protective layer absorbs impact and stress during subsequent processing steps, preventing damage to the metal or metal silicide surfaces while enabling direct fill operations
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
The method enables uniform oligomer film height across features with varying critical dimensions, allowing for selective metal deposition that fills features without seams or voids, thereby improving semiconductor device quality and process efficiency.
Implementation Method 1
exposing a semiconductor substrate surface with at least one feature formed thereon to one or more monomers to form an oligomer film
Data Source
AI summary
Embodiments of the disclosure relate to methods using an oligomer film to protect a substrate surface. The oligomer film is formed on the substrate surface with a first feature and a second feature each having a feature depth. The first feature has a first critical dimension (CD) and the second feature has a second CD. The semiconductor substrate surface is exposed to one or more monomers to form the oligomer film, and the oligomer film forms selectively on the bottom and fills a portion of the feature depth. The oligomer film fills the feature depth to substantially the same or the same height in each of the first feature and the second feature. Methods of forming semiconductor devices using the oligomer film are also disclosed.