Angular Selective Etch for Conformal Thin Film Deposition
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Solution Overview
Problem
Conventional thin film deposition methods on 3-D surfaces result in incomplete conformality and uniformity due to seam defects and voids, particularly at the edges and corners of features, where material quality deteriorates due to variations in deposition angles and sidewall evolution.
Innovation Solution
A dual beam system where the deposition and etch beams are adjusted to have equal incidence angles relative to the substrate, with the etch rate exceeding the deposition rate at critical angles, ensuring uniform coating and preventing seam formation by simultaneously depositing and etching the film on a rotated or sweeping substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional deposition methods are used on 3-D surfaces, then deposition is simpler and faster, but film uniformity and conformality deteriorate due to seam defects and voids
Solution Approach 1:
The deposition process is segmented into multiple passes with the substrate rotated to different angular positions. Each pass deposits material at a specific angle, and by segmenting the deposition into multiple angular segments, the system achieves uniform coverage without seam defects that occur in single-angle deposition.
Solution Approach 2:
The substrate is dynamically rotated during deposition to change the incidence angle of the depositing material. This dynamic angular adjustment ensures that all surfaces of 3-D features receive material at optimal angles, preventing the formation of seams and voids while maintaining deposition efficiency.
2Reliability
If ion assist is used to improve film quality at low substrate temperatures, then atomic displacement and surface diffusion are enhanced, but ion bombardment at normal incidence creates seam defects at step features
Solution Approach 1:
The system uses asymmetric angular positioning where the ion beam and deposition beam are directed at different angles relative to the substrate normal. This asymmetric configuration, combined with substrate rotation, prevents ions from always bombarding at normal incidence to step features, thereby eliminating the mechanism that creates seam defects while retaining the film quality benefits of ion assist.
Solution Approach 2:
The substrate rotation dynamically changes the relative angles between the ion beam, deposition beam, and substrate features. This dynamic adjustment ensures that no single location receives continuous normal incidence ion bombardment, preventing seam formation while maintaining the beneficial effects of ion-assisted deposition on film quality.
3Manufacturing precision
If substrate tilting is used to control incidence angles for improved film properties, then deposition angle control is achieved, but uniform deposition around 3-D features becomes difficult
Solution Approach 1:
Instead of static substrate tilting, the system employs dynamic substrate rotation that continuously changes the incidence angle during deposition. This dynamic approach automatically achieves uniform deposition around 3-D features by ensuring all surfaces are exposed to material flux from multiple angles over time, eliminating the operational complexity of manual tilting adjustments.
Solution Approach 2:
The substrate undergoes periodic rotation during deposition, cycling through different angular positions. This periodic motion ensures that all surfaces of 3-D features receive equivalent cumulative exposure to depositing material, achieving uniform deposition without requiring complex real-time angle control mechanisms.
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 achieves high-quality, conformal thin film deposition with no seam lines or voids, maintaining uniform thickness and density across 3-D features, even at critical angles where conventional methods fail, enhancing the properties and uniformity of films on complex surfaces.
Implementation Method 1
depositing a film upon a substrate with a three dimensional feature mounted on a rotated or sweeping substrate by a beam of energetic particles
Implementation Method 2
a beam of ions that simultaneously etches the surface of the patterned wafer
Implementation Method 3
energetic ions stimulate and cause atomic displacement at the surface, as well as surface atom diffusion and desorption at low substrate temperatures
Implementation Method 4
The ion energies used for ion bombardment in the conventional IAD process are typically at or near the sputtering threshold of the material on the surface
Data Source
AI summary
An ion etch assisted deposition apparatus deposits a thin film upon a substrate having a three dimensional feature, using an ion etching source and deposition source arranged at similar angles relative to the substrate and at an angle α relative to each other. The angle α is selected to be substantially equal the supplement of the angle α′ formed between the three dimensional feature on the substrate and the substrate surface. In this configuration the relative flux of energetic etch ions and deposition atoms is adjusted to prevent the growth of poor quality deposited material.