Oxide-Rich Liner Layer for Flowable CVD Gapfill Void Reduction
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Solution Overview
Problem
Semiconductor device geometries with decreasing feature sizes pose challenges in filling gaps and trenches with dielectric material, as existing techniques often result in voids or seams due to material shrinkage and porosity during hardening, leading to reduced quality and increased cracking.
Innovation Solution
A method involving the deposition of an oxygen-rich less-flowable liner layer followed by an oxygen-poor more-flowable gapfill layer, both formed within the same chamber using unexcited silicon-containing precursors, where the liner layer provides additional oxygen to the gapfill layer during curing, reducing voids and shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If highly flowable precursor materials are used to fill substrate gaps, then voids and seams are avoided during deposition, but pores and shrinkage occur during hardening
Solution Approach 1:
An oxygen-rich liner layer is deposited beforehand on the substrate and within the gap before depositing the gapfill dielectric layer. This preliminary oxygen-rich layer serves as an oxygen reservoir that will later supply oxygen during the hardening process to prevent pores and shrinkage.
Solution Approach 2:
The oxygen-rich liner layer acts as an intermediary between the oxygen environment and the gapfill dielectric layer. It provides oxygen to the gapfill layer during hardening without requiring high-temperature processing, thereby preventing material degradation while ensuring complete oxidation.
2Stability of the object's composition
If heat treatment is applied to harden flowable dielectric material, then carbon and hydroxyl groups are removed, but pores are left behind reducing material quality
Solution Approach 1:
The hardening process is performed at a lower temperature (below 400°C) compared to conventional high-temperature processing. This parameter change allows the oxygen-rich liner layer to supply oxygen to the gapfill dielectric layer, enabling complete removal of carbon and hydroxyl groups without creating pores from excessive oxygen removal.
Solution Approach 2:
The oxygen-rich liner layer serves as an oxygen source that mediates the hardening process. It provides the necessary oxygen to the gapfill dielectric layer during low-temperature processing, ensuring complete oxidation of carbon and hydroxyl groups while maintaining material density and quality.
3Ease of manufacture
If conventional deposition methods are used, then processing simplicity is maintained, but voids and seams form in high-aspect-ratio trenches
Solution Approach 1:
An oxygen-rich liner layer is deposited beforehand on the substrate and within the gap before depositing the gapfill dielectric layer. This preliminary oxygen-rich layer serves as an oxygen reservoir that will later supply oxygen during the hardening process to prevent pores and shrinkage.
Solution Approach 2:
The oxygen-rich liner layer acts as an intermediary between the oxygen environment and the gapfill dielectric layer. It provides oxygen to the gapfill layer during hardening without requiring high-temperature processing, thereby preventing material degradation while ensuring complete oxidation.
4Volume of moving object
If dielectric material is deposited to fill gaps, then gap filling is achieved, but material shrinkage creates cracks and spaces at interfaces
Solution Approach 1:
An oxygen-rich liner layer is deposited beforehand on the substrate and within the gap before depositing the gapfill dielectric layer. This preliminary oxygen-rich layer serves as an oxygen reservoir that will later supply oxygen during the hardening process to prevent pores and shrinkage.
Solution Approach 2:
The hardening process is performed at a lower temperature (below 400°C) compared to conventional high-temperature processing. This parameter change allows the oxygen-rich liner layer to supply oxygen to the gapfill dielectric layer, enabling complete oxidation of carbon and hydroxyl groups while maintaining material density and quality.
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 enhances the conformality and deposition rate of the gapfill layer, minimizing voids and cracking, and reduces material shrinkage, resulting in a higher-quality silicon oxide layer with fewer pores and improved filling of high-aspect-ratio trenches.
Implementation Method 1
The liner layer and the gapfill layer may both be formed by combining a radical component with an unexcited silicon-containing precursor... The liner layer has more oxygen content than the gapfill layer and deposits more conformally... curing the gapfill dielectric layer at an elevated temperature to transfer some of the oxygen from the oxygen-rich liner layer into the gapfill dielectric layer
Implementation Method 2
The gapfill layer may contain silicon, oxygen and nitrogen and be converted at elevated temperature to contain more oxygen and less nitrogen
Data Source
AI summary
The formation of a gap-filling silicon oxide layer with reduced volume fraction of voids is described. The deposition involves the formation of an oxygen-rich less-flowable liner layer before an oxygen-poor more-flowable gapfill layer. However, the liner layer is deposited within the same chamber as the gapfill layer. The liner layer and the gapfill layer may both be formed by combining a radical component with an unexcited silicon-containing precursor (i.e. not directly excited by application of plasma power). The liner layer has more oxygen content than the gapfill layer and deposits more conformally. The deposition rate of the gapfill layer may be increased by the presence of the liner layer. The gapfill layer may contain silicon, oxygen and nitrogen and be converted at elevated temperature to contain more oxygen and less nitrogen. The presence of the gapfill liner provides a source of oxygen underneath the gapfill layer to augment the gas phase oxygen introduced during the conversion.