Pulsed Plasma Deposition for Dielectric Step Coverage
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Solution Overview
Problem
The challenge in semiconductor processing is depositing dielectric layers over high aspect ratio features without forming voids or seams, as existing PECVD techniques tend to deposit layers more rapidly around the top than the bottom of trenches, leading to pinching-off and void formation.
Innovation Solution
The method involves in-situ deposition and treatment of a thin film using a gas mixture of precursors with simultaneous plasma presence, followed by plasma treatment with nitrogen and helium, and a plasma etch process using a fluorine-containing gas mixture, all facilitated by pulsed RF power to improve step coverage and prevent void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PECVD technique is used to deposit dielectric layer, then deposition speed is improved, but step coverage deteriorates and voids form in high aspect ratio trenches
Solution Approach 1:
The patent applies pulsed RF plasma deposition where the plasma is periodically turned on and off during the deposition process. This periodic action allows reactive species to penetrate deep into high aspect ratio trenches during plasma-on phases while preventing excessive deposition at trench openings during plasma-off phases, thereby achieving uniform step coverage without void formation while maintaining acceptable deposition rates
Solution Approach 2:
The patent changes the plasma deposition parameters by using pulsed RF power with specific duty cycles and pulse widths, and by optimizing gas flow rates and chamber pressure. These parameter changes enable better plasma penetration into deep trenches and improve the conformality of dielectric layer deposition, resolving the contradiction between deposition speed and step coverage
2Productivity
If PECVD deposits dielectric layer rapidly at top of trenches, then productivity is improved, but voids and seams are formed in trenches
Solution Approach 1:
By implementing pulsed plasma deposition with optimized pulse timing, the process prevents rapid uncontrollable deposition at trench tops while allowing sufficient material deposition in deep trenches. The periodic plasma activation ensures uniform growth throughout the trench structure, eliminating void and seam formation while maintaining overall deposition productivity
Solution Approach 2:
The patent employs preliminary plasma treatment and optimization of deposition conditions before actual dielectric layer deposition. This preliminary action prepares the trench surfaces and establishes optimal plasma conditions that prevent void formation during subsequent deposition, ensuring reliable fill of high aspect ratio trenches
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 ensures improved step coverage and densification of dielectric layers, preventing voids and seams in high aspect ratio trenches, thereby enhancing the mechanical properties and conformity of the deposited films.
Implementation Method 1
forming a dielectric layer on patterned features of the substrate by exposing the substrate to a gas mixture of a first precursor and a second precursor simultaneously with plasma present in a process chamber, wherein the plasma is formed by a first pulsed RF power
Implementation Method 2
exposing the dielectric layer to a plasma treatment using a gas mixture of nitrogen and helium in the process chamber
Implementation Method 3
etching a portion of the dielectric layer by a plasma etch process by exposing the dielectric layer to a plasma formed from a gas mixture of a fluorine-containing precursor and a carrier gas
Data Source
AI summary
Embodiments of the present disclosure relate to methods for in-situ deposition and treatment of a thin film for improved step coverage. In one embodiment, the method for processing a substrate is provided. The method includes forming a dielectric layer on patterned features of the substrate by exposing the substrate to a gas mixture of a first precursor and a second precursor simultaneously with plasma present in a process chamber, wherein the plasma is formed by a first pulsed RF power, exposing the dielectric layer to a first plasma treatment using a gas mixture of nitrogen and helium in the process chamber, and performing a plasma etch process by exposing the dielectric layer to a plasma formed from a gas mixture of a fluorine-containing precursor and a carrier gas, wherein the plasma is formed in the process chamber by a second pulsed RF power.