Sacrificial Spacer Layers for Optical Device Fabrication
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Solution Overview
Problem
Existing methods for creating air gaps in semiconductor optical devices are inefficient and costly, requiring multiple masking and etching steps, which is time-consuming and expensive.
Innovation Solution
A method using sacrificial spacer layers to create air gaps in semiconductor lasers, where a sacrificial spacer layer is deposited and then removed using a wet etch process, allowing for the fabrication of optical devices with integrated air gaps that alter mirror reflectance efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If e-beam lithography is used to define etch masks for first order Bragg reflector, then optical reflection efficiency is maximized, but manufacturing cost increases and production speed decreases
Solution Approach 1:
The patent applies preliminary action by depositing sacrificial spacer layers before the final device structure is formed. These sacrificial layers are strategically placed and then removed to create air gaps that define the Bragg reflector pattern, eliminating the need for high-resolution e-beam lithography masks while achieving the required precision through the spacer layer geometry itself.
2Manufacturing precision
If multiple masking and etching steps are used to create air gaps, then air gaps are formed in semiconductor optical devices, but manufacturing complexity and time increase
Solution Approach 1:
The patent extracts the air gap creation process from the complex multi-step masking and etching sequence by using sacrificial spacer layers that are deposited, patterned, and then removed in a simplified manner. The sacrificial layers are taken out after serving their purpose as templates, leaving behind the desired air gap structure with reduced process complexity.
Solution Approach 2:
The sacrificial spacer layers act as intermediary elements that facilitate air gap formation. These temporary structures serve as mediators between the deposition process and the final air gap configuration, enabling precise air gap creation without requiring complex direct patterning processes.
3Ease of manufacture
If optical lithography is used to define etched layers, then manufacturing cost decreases, but resolution is insufficient for first order Bragg reflector
Solution Approach 1:
The patent transitions from a two-dimensional planar patterning approach to a three-dimensional approach using sacrificial spacer layers with controlled thickness. By defining the air gap dimensions through the vertical dimension of the spacer layers rather than through lateral lithographic resolution, the method enables first order Bragg reflector fabrication using lower-resolution optical lithography.
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 method reduces the complexity and cost of creating air gaps in semiconductor devices, enabling more efficient fabrication of optical semiconductor devices with improved reflectance characteristics, reducing diffraction losses and enhancing optical reflection efficiency.
Implementation Method 1
removing a user-definable portion of each sacrificial spacer layer
Implementation Method 2
taking advantage of the index discontinuity across air gaps to selectively enhance or reduce reflections across interfaces
Implementation Method 3
interface reflections may be used to enhance performance of integrated lasers
Data Source
AI summary
The present invention is a method of fabricating an optical device using multiple sacrificial spacer layers. The first step in this process is to fabricate the underlying base structure and deposit an optical structure thereon. A facet is then created at the ends of the optical structure and alternating sacrificial and intermediate layers are fabricated on the device. A mask layer is deposited on the structure, with openings created in the layers to allow use of an etchant. User-defined portions of the spacer layers are subsequently removed with the etchant to create air gaps between the intermediate layers.