High-Aspect-Ratio Gap Fill Using Cyclic Deposition and Etch
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Solution Overview
Problem
Conventional methods struggle to completely fill high aspect ratio trenches in optical components without forming voids during the deposition process, particularly in virtual and augmented reality display devices, due to the limitations of physical vapor deposition (PVD) processes.
Innovation Solution
A method involving multiple cycles of deposition and etching processes is employed, using a cluster processing system with a PVD chamber and an etching chamber to incrementally fill gaps in material layers, ensuring complete filling without voids by removing excess deposits on sidewalls and maintaining the gap open for further deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PVD process is used to deposit material in high aspect ratio trenches, then deposition coverage on trench walls and bottom is improved, but void formation occurs due to trench opening pinching off
Solution Approach 1:
The patent segments the continuous deposition process into multiple discrete deposition steps separated by etching steps. Each deposition step deposits a portion of the trench, and the subsequent etching step removes excess material from the trench opening. This segmentation prevents the trench opening from pinching off during deposition, allowing complete trench filling without void formation.
Solution Approach 2:
The patent implements periodic alternation between deposition and etching actions. The deposition step is followed by an etching step that periodically removes excess material accumulated at the trench opening. This periodic action maintains the trench opening patent throughout the filling process, preventing void formation while achieving complete trench filling.
2Manufacturing precision
If increasing bias power during PVD deposition, then coverage on bottom surface of trench is improved, but trench opening pinches off more easily forming voids
Solution Approach 1:
The patent segments the deposition process into multiple low-bias-power deposition steps, each followed by an etching step. This segmentation allows the use of lower bias power that provides adequate bottom surface coverage without causing excessive material accumulation at the trench opening that would lead to pinching off and void formation.
Solution Approach 2:
The patent maintains continuous progress toward trench filling by immediately following each deposition step with an etching step that removes excess material. This continuous alternation ensures that bottom surface coverage is continuously improved while preventing the harmful effect of opening pinching off, maintaining both coverage quality and preventing void formation throughout the process.
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 effectively fills high aspect ratio trenches with minimal defects, such as voids or seams, by cyclically depositing and etching gap fill materials, resulting in improved performance of optical components in display devices.
Implementation Method 1
a physical vapor deposition (PVD) process to deposit a gap fill material in a gap formed in a material layer on a substrate
Implementation Method 2
a pre-cleaning etch process to remove portions of the deposited oxides from the gap and sidewalls around the opening of the gap
Implementation Method 3
performing an O2 plasma treatment process on a top surface of the gap fill material to re-oxidize the top surface
Data Source
AI summary
Embodiment of the present disclosure generally relate to optical device structures and methods for forming a metal containing interconnection structure in a high aspect ratio gap on a substrate for an optical device. In one embodiment, the method includes providing a substrate having a gap in a material layer disposed on a substrate, depositing a gap fill material in an opening of the gap, etching the gap fill material to remove portions of the gap fill material deposited in the gap, and cyclically depositing more of the gap fill material in the opening of the gap to completely fill the gap.