Optical Semiconductor Mesa Resin Step Formation
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Solution Overview
Problem
The conventional method for producing optical semiconductor devices results in electrical interconnections being easily broken due to the formation of steps between the top surface of the mesa portion and the top surfaces of the resin portion in the stripe-shaped grooves, caused by differing etch rates of the protective film and resin portion during the dry etching process.
Innovation Solution
A method involving the formation of a semiconductor structure with stripe-shaped grooves, a protective film, and a resin portion, where the resin portion has an inclined surface region that rises from the mesa portion towards the grooves, and simultaneous etching of the resin and protective films with an etch rate ratio greater than 1 to ensure the top surfaces of the resin portion are not lower than the mesa portion, preventing the formation of steps and breaking of electrical interconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the protective film and resin portion are etched by dry etching process, then the top surface of the mesa portion can be exposed, but steps are formed between the mesa surface and resin surfaces due to different etch rates, causing electrical interconnection breaking
Solution Approach 1:
The patent applies preliminary action by forming an inclined surface region in the resin portion before the etching process. This inclined surface is created at a specific angle (30°-60°) relative to the top surface of the mesa portion, which compensates for the differential etching that will occur during subsequent processing. By pre-shaping the resin portion, the patent ensures that even after etching removes material at different rates from the mesa and resin, the final surfaces remain substantially coplanar, preventing step formation and electrical interconnection breaking.
Solution Approach 2:
The patent utilizes parameter changes by controlling the etch rate ratio between the resin portion and protective film through selective etching conditions. By adjusting etching parameters (such as gas composition, power, pressure) to achieve a specific etch rate ratio (greater than 1:1), the patent compensates for the inherent differences in material etchability. This parameter control ensures that the resin portion etches faster than the protective film, maintaining surface coplanarity and preventing step formation that would otherwise occur due to material property differences.
2Manufacturing precision
If the mask opening width is set greater than the mesa width to completely expose the mesa portion, then the etching groove width becomes greater than the mesa width, causing resin portion etching and step formation
Solution Approach 1:
The patent applies preliminary action by pre-forming the inclined surface region in the resin portion before etching. This inclined surface extends laterally from the mesa portion, and when combined with the mask opening strategy (opening width ≥ mesa width), it ensures that even though the etching groove becomes wider than the mesa, the inclined surface geometry controls where the resin is removed. The inclined surface acts as a geometric guide that prevents excessive resin removal at the groove edges, maintaining proper groove width control while still achieving complete mesa exposure.
3Manufacturing precision
If the etch rate of resin portion is larger than that of protective film, then the resin surfaces are etched more, forming steps that lower the resin surfaces below the mesa surface
Solution Approach 1:
The patent applies parameter changes by deliberately controlling the etch rate ratio between resin and protective film to be greater than 1:1. This parameter adjustment is achieved through selective etching conditions (gas composition, power, pressure, temperature) that enhance the relative etching of the resin portion. By controlling this parameter, the patent ensures that the resin etches sufficiently to maintain surface coplanarity with the mesa after etching, preventing step formation despite the inherently higher resin etch rate.
Solution Approach 2:
The patent combines preliminary action with parameter changes by pre-forming the inclined surface region and then controlling the etch rate ratio during etching. The inclined surface geometry (30°-60° angle) works in conjunction with the controlled etch rate ratio to ensure that the resin portion is removed at the correct rate and location. This combination of pre-shaping and parameter control maintains surface level alignment between the mesa and resin surfaces after etching completes.
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 inhibits the formation of steps between the mesa and resin surfaces, thereby suppressing the breaking of electrical interconnections and improving the reliability of the optical semiconductor device production process.
Implementation Method 1
the step of etching the resin portion and the protective film includes the substeps of etching the resin portion until the inclined surface region comes into contact with the protective film, and simultaneously etching the resin portion and the protective film with an etch rate of the resin portion larger than an etch rate of the protective film
Data Source
AI summary
A method for producing an optical semiconductor device includes the steps of forming a semiconductor structure; forming a mask on the semiconductor structure; etching the semiconductor structure with the mask to form first and second stripe-shaped grooves and a mesa portion; forming a protective film on a top surface and side surfaces of the mesa portion; forming a resin portion on the protective film; etching the resin portion and the protective film formed on the top surface; forming an upper electrode on the top surface; and forming an electrical interconnection on the resin portion. The resin portion has an inclined surface region that rises from a first point above the mesa portion toward a second point above the first stripe-shaped groove. The step of etching the resin portion and the protective film includes the substeps of etching the resin portion and simultaneously etching the resin portion and the protective film.