Semiconductor Diode Etching Sequence for Precise Pad Dimensions
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Solution Overview
Problem
Existing semiconductor diode fabrication processes face issues with unwanted over-etching during dry and wet etching, leading to undesired lateral and vertical dimension degradation, particularly affecting the performance of semiconductor diodes in on-silicon photonics and hybrid laser sources.
Innovation Solution
A process involving multiple hard mask layers and selective etching steps, including dry and wet etching, is used to form semiconductor pads with precise lateral and vertical dimensions, ensuring minimal degradation of underlying layers by avoiding vertical over-etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet etching is used to remove residual confinement layer, then the active segment can be freed, but lateral undercutting degrades the dimensions of the active segment
Solution Approach 1:
The confinement layer removal is divided into two separate steps: first dry etching to create initial exposure, then wet etching to complete the removal. This segmentation allows each etching method to be optimized for its specific function, preventing undercutting while ensuring complete removal.
Solution Approach 2:
The dry etching step is performed as a preliminary action before wet etching. This preliminary dry etching creates a controlled exposure of the active segment without causing lateral undercutting, preparing the structure for subsequent complete removal by wet etching.
2Manufacturing precision
If dry etching is used to structure the semiconductor pad, then vertical precision can be achieved, but non-uniform etch depth causes undesired vertical etching
Solution Approach 1:
The etching process applies different qualities to different regions: dry etching provides vertical precision where needed, while the subsequent wet etching provides uniform material removal. The process tailors the etching characteristics to the specific requirements of each region of the semiconductor structure.
Solution Approach 2:
The patent uses a composite etching approach combining two different etching methods (dry and wet) with different characteristics. This composite process leverages the vertical precision of dry etching and the uniformity of wet etching to achieve both precision and reliability.
3Device complexity
If conventional single-step etching is used, then the process is simple, but over-etching degrades the dimensions of semiconductor layers
Solution Approach 1:
The etching process is segmented into multiple steps (dry etching followed by wet etching) with distinct functions. Each step is optimized for its specific purpose, preventing over-etching while maintaining process simplicity through clear separation of functions.
Solution Approach 2:
The dry etching step acts as an intermediary between the initial structure and the final configuration. It provides a controlled transition that prevents direct over-etching by wet etching, mediating the dimensional changes to preserve accuracy.
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
The process ensures the semiconductor diode achieves desired dimensions, preserving performance by minimizing degradation of underlying layers and maintaining uniformity, particularly suitable for hybrid laser diodes.
Implementation Method 1
depositing a first hard mask on the upper layer; depositing and structuring a second hard mask
Implementation Method 2
dry etching the upper layer to form the upper segment; dry etching the active layer to form the active segment
Implementation Method 3
dry etching
Implementation Method 4
wet etching the first residual segment selectively with respect to the active layer; wet etching the second residual segment selectively with respect to the lower layer
Data Source
AI summary
The invention relates to a process for fabricating a semiconductor diode (1) via transfer of a semiconductor stack (20) then local etching to form a semiconductor pad (30), the production of the semiconductor pad (30) comprising a plurality of sequences comprising a dry etch that leaves a residual segment (23.1; 22.1), formation of a hard-mask spacer (42.1; 43.1), then a wet etch of the residual segment (23.1; 22.1).