Tungsten Pillar Formation via Self-Aligned Spacer Patterning
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Solution Overview
Problem
The semiconductor industry faces challenges in filling high aspect ratio trenches with high-quality dielectric materials, particularly for smaller critical dimensions, as existing methods struggle with physical isolation and irregularly shaped gaps between devices.
Innovation Solution
A method involving the deposition of a patterned film on a substrate, followed by the thermal decomposition of silicon precursors to form amorphous silicon films, which are then recessed and converted to tungsten films using WF6, and subsequently oxidized to form tungsten pillars that extend from the features, ensuring precise filling and expansion without seam formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional gapfill and hardmask methods are used, then existing processes can be maintained, but filling high aspect ratio trenches with small critical dimensions becomes increasingly difficult
Solution Approach 1:
The filling process is divided into multiple sequential steps: depositing mandrel material, forming spacers, removing mandrels, and filling remaining spaces. This segmentation allows each step to be optimized independently, achieving precise filling of high aspect ratio trenches while managing process complexity
Solution Approach 2:
Mandrel structures are deposited and patterned in advance to define the final feature geometry. These preliminary structures guide subsequent spacer formation and material deposition, ensuring precise positioning and dimensions before the actual filling occurs
2Ease of manufacture
If selective deposition methods are used with patterned masks, then material can be deposited on selected regions, but the process becomes complex involving mask deposition, patterning, and removal
Solution Approach 1:
The mandrel structures serve dual purposes: they act as temporary placeholders during fabrication and automatically define the geometry of the final features through spacer formation. This self-service approach eliminates the need for separate pattern transfer steps, reducing overall process complexity while maintaining selective deposition capability
Solution Approach 2:
The invention changes the physical and chemical parameters of materials at different process stages. Mandrel materials are selected to be removable under specific conditions (e.g., selective etching), while spacer materials are chosen for their ability to conformally coat and maintain dimensional stability, enabling complex geometry formation through parameter optimization
3Productivity
If trench dimensions are reduced for smaller transistors, then more functionality per unit area is achieved, but physical isolation and gap filling become increasingly difficult
Solution Approach 1:
The structure is built hierarchically with spacers nested on mandrels, and fill materials nested within spacer-defined spaces. This nested approach allows precise control of dimensions at each level, enabling the formation of sub-10nm features while maintaining manufacturing precision despite reduced trench dimensions
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 effective filling of high aspect ratio structures with small dimensions, achieving self-aligned patterning and gap filling without seams, maintaining feature shape fidelity and providing high-quality metal oxide films for advanced chip designs.
Implementation Method 1
The amorphous silicon film is etched with a hydrogen plasma or hydrogen radicals to recess the amorphous silicon film
Implementation Method 2
The tungsten film is oxidized to expand the tungsten film to form tungsten pillars that extending substantially straight up from the at least one feature
Implementation Method 3
The substrate surface is exposed to a silicon precursor comprising one or more of silane, disilane, trisilane or tetrasilane to deposit an amorphous silicon film by thermal decomposition
Data Source
AI summary
Methods of forming self-aligned patterns are described. A film material is deposited on a patterned film to fill and cover features formed by the patterned film. The film material is recessed to a level below the top of the patterned film. The recessed film is converted to a metal film by exposure to a metal precursor followed by volumetric expansion of the metal film.