Plasma-Inhibited Gap Filling for Vertical and Lateral Features
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Solution Overview
Problem
Conventional deposition processes struggle to form seam-free and void-free gapfill structures in both vertical and lateral features of semiconductor devices, particularly in 3D DRAM memory stacks, due to limitations in filling high aspect ratio trenches.
Innovation Solution
An anisotropic plasma inhibition process is applied to selectively inhibit certain surfaces of vertical and lateral features, followed by an atomic layer deposition (ALD) process to control the growth rate of the gapfill structure, ensuring complete filling without seams or voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition processes are used to fill vertical high aspect ratio trenches, then the filling process is simpler, but the gapfill structures contain seams and voids
Solution Approach 1:
The patent applies preliminary plasma inhibition treatment to the trench surfaces before deposition. This pre-treatment creates a non-uniform surface state that controls subsequent material deposition, preventing seam and void formation by inhibiting growth at specific locations where defects would otherwise occur.
Solution Approach 2:
The patent creates local variations in surface properties through selective plasma inhibition. Different regions of the trench surface receive different levels of inhibition, causing the deposition rate to vary locally. This local quality control ensures that material fills gaps and prevents defects at critical locations while maintaining overall filling efficiency.
2Manufacturing precision
If uniform deposition is applied to all surfaces, then the deposition process is simpler, but lateral features cannot be properly filled
Solution Approach 1:
The patent applies selective plasma inhibition to different surface orientations. Horizontal surfaces (lateral feature openings) receive stronger inhibition than vertical surfaces, causing deposition to preferentially occur on vertical walls while limiting growth at horizontal openings. This local differentiation enables proper filling of lateral features without requiring separate deposition processes.
Solution Approach 2:
The patent changes the deposition parameters dynamically by modifying surface energy states through plasma treatment. By altering the chemical state of surface sites rather than changing physical deposition conditions, the process achieves direction-selective filling that accommodates both vertical and lateral feature geometries within a single deposition step.
3Productivity
If higher deposition rates are used to fill features faster, then productivity increases, but defects such as seams and voids increase
Solution Approach 1:
The plasma inhibition step is performed before deposition to prepare the surface for high-rate filling. By pre-establishing the inhibition pattern, the subsequent high-rate deposition can proceed without forming defects, as the inhibition sites are already positioned to prevent seam and void formation during rapid material accumulation.
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 enables the formation of seamless and void-free gapfill structures in both vertical and lateral features, enhancing the fabrication of 3D semiconductor devices by minimizing defects and improving device reliability.
Implementation Method 1
exposing surfaces of the vertical feature and the plurality of lateral features to an anisotropic plasma generated from the inhibiting gas mixture to form an inhibition gradient on surfaces of the vertical feature and the plurality of lateral features
Implementation Method 2
depositing a gapfill structure in the vertical feature and lateral features
Data Source
AI summary
A method of processing a substrate with a vertical feature and a plurality of lateral features extending from the vertical feature is provided. The method includes exposing surfaces of the vertical feature and the plurality of lateral features to an anisotropic plasma generated from an inhibiting gas mixture to form an inhibition gradient on surfaces of the vertical feature and the plurality of lateral features, and depositing a gapfill structure in the vertical feature and lateral features. In an embodiment, the inhibition gradient provides for varying the growth rate of the gapfill structure in the vertical feature and the plurality of lateral features.