III-V Optical Semiconductor Waveguide Layout for Low-Loss Coupling
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Solution Overview
Problem
Existing optical semiconductor elements face issues with unintended etching during manufacturing, which damages the semiconductor element, and there is a need to improve light coupling efficiency to reduce light loss.
Innovation Solution
The optical semiconductor element incorporates a substrate with specific waveguide and recess configurations, including a first and second recess, a terrace, and slab portions, which form a multi-mode interferometer (MMI) structure to seal recesses and enhance light coupling, using III-V group compound semiconductors and wet-etching techniques to minimize etchant intrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet-etching is performed on the semiconductor element after bonding, then the semiconductor element can be processed and shaped, but unintended etching damages the semiconductor element
Solution Approach 1:
A protective film is applied to the semiconductor element before wet-etching. This protective film acts as an intermediary layer that allows the etching process to be performed on the waveguide and other structures while protecting the semiconductor element from unintended etching damage. The protective film is selectively removed or designed to be etch-resistant in critical areas.
Solution Approach 2:
The patent applies different protective measures to different areas of the semiconductor structure. The protective film is applied selectively to areas requiring protection during etching, while leaving other areas exposed for proper etching. This localized approach allows processing where needed while protecting critical semiconductor regions.
2Loss of energy
If the recess structure is used for bonding and light coupling, then light coupling efficiency is improved, but etchant can intrude into the recess and cause unintended etching
Solution Approach 1:
The protective film serves as an intermediary barrier that prevents etchant from intruding into the recess structure while allowing the recess to maintain its light-coupling function. The protective film is applied to the recess walls and bottom, blocking etchant access while being transparent or non-interfering to light propagation.
Solution Approach 2:
The protective film is applied in advance before the wet-etching process to preemptively block etchant intrusion into the recess. This preliminary protective action prevents the harmful effect of etchant contact before it can occur, while the recess structure remains intact for its intended light coupling purpose.
3Loss of energy
If the waveguide and recess configuration is optimized for light coupling, then light transfer efficiency improves, but the structure becomes more complex
Solution Approach 1:
The protective film serves multiple functions simultaneously: it protects the semiconductor element from etching damage, prevents etchant intrusion into the recess, and maintains the optical properties of the waveguide structure. This multi-functionality reduces the need for additional separate protective structures, thereby managing complexity while achieving multiple goals.
Data Source
AI summary
An optical semiconductor element includes a substrate having a silicon layer, and a semiconductor element formed of III-V group compound semiconductor and bonded to the silicon layer. The silicon layer has a first waveguide, a second waveguide, a first recess, a second recess, a terrace, and a first slab portion. The first recess and the second recess are portions recessed from a surface of the first waveguide, a surface of the second waveguide, a surface of the terrace, and a surface of the first slab portion. The first recess and the terrace are arranged on either side of the first waveguide in an order of the first recess and the terrace. The semiconductor element has a protruding portion, a second slab portion, and a third slab portion.