Variable-Depth Device Structures via Cyclic Etching

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Solution Overview

Problem

Existing methods for fabricating optical devices for augmented and virtual reality struggle with non-uniform properties, making it challenging to effectively overlay virtual images on ambient environments.

Innovation Solution

A method involving a cyclic-etch process using gray-tone resist and selective etching techniques to form device structures with variable depths, allowing for the creation of nanostructures with precise control over depth and angle, suitable for use in optical devices like waveguides and metasurfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional fabrication methods are used for optical devices, then the manufacturing process is simpler, but the device structures exhibit non-uniform properties

Engineering Contradiction:
Improveuniformity of device structuresVSAvoidcomplexity of fabrication process
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The fabrication process is divided into multiple cyclic steps of depositing material layers and etching patterns. Each cycle creates a segment of the final variable-depth structure, allowing progressive formation of complex non-uniform geometries through repeated simple operations. This segmentation enables precise control over device structure uniformity while maintaining manageable process complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs periodic deposition and etching cycles to build the device structure layer by layer. Each period consists of depositing a material layer followed by etching a pattern, repeated multiple times to accumulate the desired variable-depth structure. This periodic action transforms a complex single-step process into manageable periodic operations, achieving high manufacturing precision.

Inventive Principle:
Principle #19Periodic action

2Manufacturing precision

If multiple processing steps are used to achieve uniform device structures, then the manufacturing precision improves, but the productivity decreases

Engineering Contradiction:
Improveuniformity of device structuresVSAvoidfabrication throughput
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

Multiple deposition and etching operations are merged into a single integrated cyclic process. Rather than treating each layer and pattern as separate manufacturing steps, the patent combines them into unified cycles that can be automated and executed continuously. This merging maintains high manufacturing precision while improving productivity by reducing process transitions and setup time.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cyclic deposition-etching process is designed to continue without interruption, with each cycle seamlessly transitioning into the next. Material layers are deposited and etched in continuous succession, maximizing the utilization of manufacturing equipment and maintaining steady production flow. This continuity preserves manufacturing precision through consistent process conditions while significantly boosting fabrication throughput.

Inventive Principle:
Principle #20Continuity of useful action

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 enables the fabrication of optical devices with higher resolution and fewer processing steps, resulting in improved uniformity and effectiveness in overlaying virtual images on ambient environments.

Implementation Method 1

developing the resist material to form a gray-tone pattern

Methodology Applied
Scientific EffectPhotochemical development: Photopolymerisation

Implementation Method 2

etching a resist segment of the gray-tone pattern using a resist etch process selective to the resist material and etching a device segment of the device material using a device pattern etch process selective to the device material

Methodology Applied
Scientific EffectSelective etching: Ablation

Data Source

PatentEP3969959B1Methods of forming variable-depth device structures
Publication Date: 2024.08.14 APPLIED MATERIALS INC
  • EP3969959B1 patent drawingFigure 1
  • EP3969959B1 patent drawingFigure 2
  • EP3969959B1 patent drawingFigure 3A~3B

AI summary

A method for forming a device structure is disclosed. The method of forming the device structure includes forming a variable-depth structure in a device material layer using cyclic-etch process techniques. A plurality of device structures is formed in the variable-depth structure to define vertical or slanted device structures therein. The variable-depth structure and the vertical or slanted device structures are formed using an etch process.