Topographic Selective Deposition for High-Aspect-Ratio Feature Clogging
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving accurate and precise patterning of features in three-dimensional structures, such as fin field-effect transistors, due to heavy deposition on top and sidewall surfaces during plasma processing, leading to feature clogging and reduced critical dimension.
Innovation Solution
A pulsed plasma process is employed for topographic selective deposition, where a carbonaceous layer is deposited on the bottom surface of high aspect ratio features using fluorocarbon ions and trimmed using fluorine radicals, minimizing sidewall deposition and enhancing anisotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma processing is used to pattern features in three-dimensional structures, then deposition occurs on top and bottom surfaces, but heavy deposition on sidewalls causes feature clogging and reduces critical dimension
Solution Approach 1:
The patent applies periodic pulsed plasma processing with alternating deposition and etch phases. During deposition phases, carbonaceous material is deposited on horizontal surfaces; during etch phases, sidewall material is removed. This periodic alternation prevents sidewall clogging while maintaining critical dimension precision in high aspect ratio structures.
Solution Approach 2:
The patent changes plasma processing parameters between deposition and etch phases, including adjusting source power, bias power, and gas composition. These parameter changes enable selective deposition on horizontal surfaces while preventing harmful sidewall accumulation, resolving the contradiction between achieving desired deposition and avoiding feature clogging.
2Productivity
If continuous plasma deposition is used to deposit carbonaceous layer, then deposition efficiency is high, but anisotropy is reduced and sidewall deposition increases
Solution Approach 1:
The pulsed plasma process alternates between deposition phases (high source power, low bias power) that efficiently deposit carbonaceous material on horizontal surfaces and etch phases (low source power, high bias power) that remove sidewall material. This periodic action maintains high overall deposition efficiency while preserving anisotropy by selectively removing unwanted sidewall deposits.
Solution Approach 2:
The continuous deposition process is segmented into discrete pulsed phases with distinct parameters. Each pulse consists of a deposition portion and an etch portion, allowing independent optimization of deposition efficiency and anisotropy control. This segmentation enables the system to achieve both high productivity and shape precision.
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 achieves selective deposition on top and bottom surfaces while reducing undesired sidewall deposition, thereby preventing feature clogging and maintaining the critical dimension of high aspect ratio features.
Implementation Method 1
the fluorocarbon ions polymerizing on the bottom surface to form the carbonaceous layer
Implementation Method 2
the fluorine radicals trimming the carbonaceous layer
Implementation Method 3
sustaining a plasma generated from the gas in the plasma processing chamber
Data Source
AI summary
A method of processing a substrate that includes: flowing a gas including a fluorocarbon to a plasma processing chamber; sustaining a plasma generated from the gas; depositing a carbonaceous layer over the substrate by exposing the substrate to the plasma, the substrate having a recess having an aspect ratio between 10:1 and 100:1, the depositing including a pulsed plasma process including: during a first time duration, setting a source power (SP) at a first SP level and a bias power (BP) at a first BP level, where the plasma includes fluorocarbon ions polymerizing on a bottom surface to form the carbonaceous layer, and during a second time duration, setting the SP at a second SP level higher than the first SP level and the BP at a second BP level lower than the first BP level, where the plasma includes fluorine radicals trimming the carbonaceous layer.