Semiconductor Optical Modulator Ti Adhesion Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor optical modulators face issues with the peeling off of metal electrodes from insulating films due to inferior adhesion, particularly when the resin layer thickness exceeds 2 μm, complicating the photolithography process and reducing the reliability of ohmic contacts.
Innovation Solution
The process involves forming a first metal film, including titanium, on the insulating layer before depositing the second metal film, which enhances adhesion and simplifies the photolithographic process by ensuring the second metal film remains securely attached, even with thick insulating layers and deep openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resin layer thickness is increased to reduce parasitic capacitance, then the high-frequency performance is improved, but the photolithography process becomes difficult to execute and the metal electrode adhesion deteriorates
Solution Approach 1:
The patent applies preliminary action by forming the Ti adhesion layer on the insulating film surface before depositing the AuZn metal electrode. This pre-prepared adhesion layer ensures that when thick resin layers (≥2μm) are used, the metal electrode maintains secure attachment without peeling issues, enabling both thick resin layer fabrication and successful photolithography processing.
2Reliability
If the resin layer thickness is increased to reduce parasitic capacitance, then the high-frequency performance is improved, but the metal electrode peels off from the insulating film
Solution Approach 1:
The patent introduces Ti as an intermediary adhesion layer between the insulating film and the AuZn metal electrode. This intermediate layer with superior adhesion properties to inorganic materials prevents the peeling problem that occurs when thick resin layers are used, thereby maintaining both high-frequency performance and electrode integrity.
3Reliability
If the opening depth is increased to expose the mesa top with thick insulating layer, then the electrode contact is improved, but the photolithography precision deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-forming the Ti adhesion layer across the entire insulating film surface before defining the metal electrode pattern through photolithography. This allows the use of deep openings to expose the mesa top for good electrode contact while maintaining photolithography precision, as the adhesion layer is already in place to prevent any peeling during the deep etching 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 prevents peeling of the second metal film from the insulating layer, simplifies the photolithographic process, and enhances the reliability of p-type semiconductor contacts, maintaining high-frequency performance while allowing for thicker resin layers.
Implementation Method 1
forming the first metal film along the opening but without an inside of the opening on the insulating layer, where the first metal film includes Ti; and covering the exposed top of the mesa and the first metal film on the insulating layer by the second metal film
Data Source
AI summary
A process to manufacture a semiconductor optical modulator is disclosed, in which the process easily forms a metal film including AuZn for the p-ohmic metal even a contact hole has an enhanced aspect ration. The process forms a mesa including semiconductor layers first, then, buries the mesa by a resin layer sandwiched by insulating films. The resin layer provides an opening reaching the top of the mesa, into which the p-ohmic metal is formed. Another metal film including Ti is formed on the upper insulating film along the opening.