Selective Polysilicon Gap Fill Using Flowable Polymer Protection
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Solution Overview
Problem
Conventional deposition processes struggle with defect-free filling of small features in semiconductor manufacturing due to the challenge of selectively depositing high-quality silicon on metal or metal silicide without damaging the underlying material, especially as device geometries shrink and thermal budgets are reduced.
Innovation Solution
A method involving physical vapor deposition of a silicon layer, followed by the formation of a flowable polymer film within the feature, selective removal of the silicon layer from the top surface and sidewalls, and subsequent removal of the polymer film to expose the silicon layer on the bottom, which is then oxidized to form a silicon oxide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If physical vapor deposition (PVD) is used to deposit silicon, then high quality silicon can be obtained, but the process is not selective and damages underlying metal or metal silicide
Solution Approach 1:
A flowable polymer film is introduced as an intermediary protective layer between the PVD silicon deposition process and the underlying metal or metal silicide. The polymer is deposited conformally across the substrate, then selectively removed from field regions while remaining intact in trench regions during silicon deposition. This mediator allows high-quality silicon deposition via PVD without direct contact between the deposition process and the underlying metal, preventing damage while maintaining selectivity.
Solution Approach 2:
The polymer film's presence is made non-uniform across different regions of the substrate. In trench regions, the polymer remains to protect the underlying metal during silicon deposition. In field regions, the polymer is selectively removed to allow subsequent processing. This local differentiation enables selective silicon deposition only in trench regions while preserving the underlying metal where needed.
2Manufacturing precision
If selective polysilicon deposition is attempted on metal or metal silicide, then selectivity can be achieved, but the process causes damage to the underlying material
Solution Approach 1:
The flowable polymer serves as a protective intermediary layer that enables selective silicon deposition. The polymer is conformally deposited over the entire substrate including metal and metal silicide regions, then selectively removed from field regions. During subsequent PVD silicon deposition, silicon is deposited only in trench regions where the polymer was removed, achieving selectivity without direct exposure of the underlying metal to the deposition process, thus preventing damage.
3Productivity
If conventional gap fill processes are used, then features can be filled, but defect-free filling becomes difficult as device geometries shrink
Solution Approach 1:
The gap fill process is segmented into distinct sequential steps: (1) conformal polymer deposition, (2) selective polymer removal from field regions, (3) PVD silicon deposition in trench regions, (4) polymer removal from trench regions, and (5) silicon oxidation. This segmentation allows each step to be optimized independently, ensuring defect-free filling even as device geometries shrink and thermal budgets are reduced.
Solution Approach 2:
The flowable polymer acts as a temporary intermediary structure that defines the deposition geometry. By conformally depositing the polymer and then selectively removing it from field regions, the process creates a precise template for subsequent silicon deposition. This intermediary approach ensures that silicon is deposited only where needed, achieving defect-free gap filling in scaled devices.
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
Enables selective and defect-free deposition of polysilicon in a bottom-up fashion, protecting the underlying metal or metal silicide and ensuring high-quality silicon deposition without residue or damage.
Implementation Method 1
depositing a first silicon (Si) layer by physical vapor deposition (PVD) on a semiconductor substrate surface
Implementation Method 2
oxidizing the remaining portion of the first silicon (Si) layer to form a first silicon oxide (SiOx) layer on the bottom
Data Source
AI summary
Embodiments of the disclosure relate to methods of selectively depositing polysilicon after forming a flowable polymer film to protect a substrate surface within a feature. A first silicon (Si) layer is deposited by physical vapor deposition (PVD). The flowable polymer film is formed on the first silicon (Si) layer on the bottom. A portion of the first silicon (Si) layer is selectively removed from the top surface and the at least one sidewall. The flowable polymer film is removed. In some embodiments, a second silicon (Si) layer is selectively deposited on the first silicon (Si) layer to fill the feature. In some embodiments, the remaining portion of the first silicon (Si) layer on the bottom is oxidized to form a first silicon oxide (SiOx) layer on the bottom, and a silicon (Si) layer or a second silicon oxide (SiOx) layer is deposited on the first silicon oxide (SiOx) layer.