Semiconductor Optical Device Waveguide Ridge Contact Area
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Solution Overview
Problem
Existing methods for manufacturing semiconductor optical devices with waveguide ridges face challenges in maintaining a sufficient contact area between the electrode layer and the contact layer, leading to increased contact resistance and operating voltage, particularly in blue-violet lasers where the contact layer material has high resistance.
Innovation Solution
A method involving a photolithography process to form a laminated semiconductor structure with a first resist pattern creating concave portions for waveguide ridge formation, followed by a second resist pattern that exposes the top surface of the second semiconductor layer while leaving the insulating film on the sides, allowing for the electrode layer to be formed without reducing the contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If lift-off process is used to form insulating film with opening, then waveguide ridge structure is formed, but contact area between electrode layer and contact layer is reduced
Solution Approach 1:
The method performs preliminary actions by forming the insulating film covering the entire top surface before creating the opening. The opening is then formed through etching the insulating film in a specific region, ensuring that the electrode layer can contact the contact layer through this pre-prepared opening while the rest of the insulating film remains intact to provide insulation.
Solution Approach 2:
The insulating film is segmented into two functional regions: a covering portion that insulates the top surface and a removed portion (opening) that allows electrode contact. This segmentation is achieved by selective etching of the insulating film in the region corresponding to the waveguide ridge, creating distinct functional zones within the same insulating layer.
2Shape
If contact area is reduced, then waveguide ridge structure is achieved, but contact resistance increases
Solution Approach 1:
The method ensures sufficient contact area is preserved by preliminarily forming the insulating film covering and then selectively removing it only in the necessary region. This preliminary structuring allows the electrode layer to maintain adequate contact with the contact layer through the opening, preventing excessive contact resistance while achieving the waveguide ridge shape.
3Shape
If contact resistance increases, then waveguide ridge structure is formed, but operating voltage increases
Solution Approach 1:
By preliminarily forming the insulating film covering and then selectively creating an opening, the method ensures that the electrode layer maintains sufficient contact area with the contact layer. This prevents excessive contact resistance and consequently avoids increasing the operating voltage, while still achieving the desired waveguide ridge structure.
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 formation of semiconductor optical devices with a high yield by ensuring a reliable contact between the electrode and the semiconductor layer, reducing contact resistance and operating voltage, and simplifying the manufacturing process.
Implementation Method 1
forming by a photolithography process a first resist pattern of a resist film disposed on a top surface of a laminated semiconductor structure
Implementation Method 2
removing portions of an upper surface side of the second semiconductor layer by dry etching using the first resist pattern as a mask
Data Source
AI summary
A method for manufacturing a laser diode includes: providing a semiconductor structure in which semiconductor layers are laminated; forming a waveguide ridge in the layers; forming an SiO2 film over the entire surface; forming a second resist pattern covering the SiO2 film in channels adjacent the waveguide ridge such that top surfaces of the second resist pattern in the channels are higher than the top surface of a p-GaN layer in the waveguide ridge and lower than the top surface of the SiO2 film on the top of the waveguide ridge, the second resist pattern exposing the top surface of the SiO2 film on the top of the waveguide ridge; removing the SiO2 film, using the second resist pattern as a mask, to expose the top surface of the p-GaN layer in the waveguide ridge; and forming an electrode layer on the top surface of the p-GaN layer.