PECVD Amorphous Silicon Gap Fill for Void-Free Trench Filling
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Solution Overview
Problem
In semiconductor processing, existing deposition processes struggle to fill high aspect ratio structures with void-free gap fill materials, resulting in poor quality insulating materials with high wet etch rate ratio and high stress, which require subsequent curing and annealing processes.
Innovation Solution
A method involving cyclic deposition and removal of amorphous silicon layers using plasma enhanced chemical vapor deposition (PECVD) with silane-containing precursors, where the first and second amorphous silicon layers are deposited on the bottom and surface of features, respectively, with exposed sidewall portions, and subsequent layers are added until the feature is filled seamlessly from the bottom up, eliminating the need for curing and annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If flowable chemical vapor deposition (FCVD) is used to deposit gap fill materials, then the deposition process can be performed, but the as-deposited materials have poor quality with high wet etch rate ratio and high stress
Solution Approach 1:
The patent changes the deposition parameters by using plasma-enhanced chemical vapor deposition (PECVD) instead of FCVD, controlling substrate temperature between 150-650°C, and using silane-containing precursors to deposit amorphous silicon layers with improved quality characteristics including reduced stress and better etch rate ratios
Solution Approach 2:
The gap fill process is segmented into multiple deposition cycles where amorphous silicon layers are deposited in controlled stages, with intermediate removal of excess material from sidewalls, allowing precise control over the final gap fill quality and stress characteristics
2Manufacturing precision
If FCVD is used for gap fill deposition, then the process can be completed, but subsequent curing and annealing processes are required to improve material quality
Solution Approach 1:
The patent performs preliminary action by depositing amorphous silicon layers with inherently good quality characteristics during the PECVD process itself, controlling deposition parameters to achieve low stress and appropriate etch rate ratios without requiring subsequent curing or annealing steps, thus eliminating post-deposition thermal processing
Solution Approach 2:
By changing from FCVD to PECVD and controlling substrate temperature and precursor flow, the patent achieves gap fill materials with sufficient quality directly from deposition, eliminating the need for additional thermal processing steps and improving substrate throughput
3Manufacturing precision
If existing deposition processes are used, then deposition can be performed, but void-free filling of high aspect ratio spaces becomes increasingly difficult
Solution Approach 1:
The patent employs dynamic control of the deposition process through multiple cycles of amorphous silicon layer deposition and selective removal, adjusting process parameters at each stage to achieve complete void-free filling of high aspect ratio structures while maintaining material quality
Solution Approach 2:
The filling process is divided into sequential deposition cycles where material is deposited and then excess is removed from sidewalls, progressively building up the gap fill material in a controlled manner that ensures complete void elimination even in high aspect ratio features
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 results in high-quality, seamless amorphous silicon gap fill materials with reduced bridging and void formation, improving the quality of gap fill materials and eliminating the need for subsequent thermal processing steps, enhancing substrate throughput and material quality.
Implementation Method 1
depositing a first amorphous silicon layer on a bottom of a feature formed in the substrate and a second amorphous silicon layer on a surface of the substrate by plasma enhanced chemical vapor deposition (PECVD)
Implementation Method 2
heating a substrate disposed in a process chamber to a temperature ranging from about 150 degrees Celsius to about 650 degrees Celsius
Data Source
AI summary
Embodiments of the present disclosure relate to processes for filling trenches. The process includes depositing a first amorphous silicon layer on a surface of a layer and a second amorphous silicon layer in a portion of a trench formed in the layer, and portions of side walls of the trench are exposed. The first amorphous silicon layer is removed. The process further includes depositing a third amorphous silicon layer on the surface of the layer and a fourth amorphous silicon layer on the second amorphous silicon layer. The third amorphous silicon layer is removed. The deposition/removal cyclic processes may be repeated until the trench is filled with amorphous silicon layers. The amorphous silicon layers form a seamless amorphous silicon gap fill in the trench since the amorphous silicon layers are formed from bottom up.