PEALD Low-k Silicon Oxide Deposition for Recess Step Coverage
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Solution Overview
Problem
As semiconductor devices shrink, the uniformity of low-k films deposited in recess structures becomes poor, leading to non-conformal film deposition and increased dielectric constant, which affects the RC delay and response time of the devices.
Innovation Solution
A PEALD method is used to form a low-k film by cyclically supplying multiple silicon precursors and an oxidant, which improves step coverage and reduces the dielectric constant to 3.5 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PECVD method is used to deposit low-k film, then film deposition speed is high, but film uniformity in recess structure becomes poor
Solution Approach 1:
The patent segments the deposition process into multiple sequential half-cycles, alternating between first and second precursors. This segmentation allows each precursor to deposit on different surface regions, ensuring complete and uniform coverage of the recess structure while maintaining high deposition speed through continuous alternating cycles.
Solution Approach 2:
The patent employs periodic action by alternating between first precursor supply and second precursor supply in sequential half-cycles. This periodic alternation ensures that both precursors have opportunities to deposit on the recess surface, achieving uniform conformal coverage while maintaining high overall deposition rate through the continuous periodic cycles.
2Manufacturing precision
If PECVD method is used, then k-value reduction is achieved, but conformal deposition in narrow gap structure deteriorates
Solution Approach 1:
The patent applies local quality by using two different precursors with distinct deposition characteristics. The first precursor preferentially deposits on certain surface regions while the second precursor deposits on other regions, creating locally optimized deposition that results in overall conformal coverage of the narrow gap structure.
Solution Approach 2:
By segmenting the deposition into alternating half-cycles with different precursors, the patent ensures that each precursor can access and deposit on different portions of the recess surface. This segmentation enables conformal deposition in narrow gaps while achieving the required k-value reduction through the combined effect of both precursors.
3Manufacturing precision
If single precursor is used in ALD, then process simplicity is maintained, but step coverage in recess structure becomes insufficient
Solution Approach 1:
The patent segments the ALD process into alternating half-cycles using two different precursors. This segmentation enables each precursor to contribute to step coverage on different portions of the recess structure, achieving superior overall step coverage that would not be possible with a single precursor, while the segmented nature maintains process control.
Solution Approach 2:
Through periodic alternation between first and second precursor supply in sequential half-cycles, the patent achieves enhanced step coverage in recess structures. The periodic action ensures that both precursors sequentially access the recess surfaces, improving step coverage while the regular periodic pattern keeps the process complexity manageable.
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 conformal film deposition with a low dielectric constant, improving step coverage and reducing RC delay, thereby enhancing the performance and speed of semiconductor devices.
Implementation Method 1
a plasma enhanced atomic layer deposition (PEALD) method
Data Source
AI summary
Provided is a method for forming a low-k film by PEALD. In one embodiment, a first silicon precursor is supplied, followed by a second silicon precursor in order to form a silicon precursor layers. Then oxidant is supplied to form a silicon oxide film. The method further comprises a post treatment in order to remove a moisture from the film. The method according to the disclosure enables to form a silicon oxide film with desired low-k value and good step coverage on the recess structure.