Optoelectronic Device Contact Area Precision via Single Photolithography
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Solution Overview
Problem
Existing methods for producing optoelectronic devices with semiconductor crystals face challenges in reproducibly achieving optimal contact area sizes, leading to variations in forward voltages and light yields due to adjustment tolerances during lithographic processes.
Innovation Solution
A method involving a semiconductor crystal with a dielectric layer, a patterned photoresist layer, and sequential application of metal layers, where the contact area size is defined by the photoresist opening, allowing for precise and reproducible contact area formation using a single photolithographic step, reducing light absorption and enabling higher light yields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple lithographic method steps are used to define contact area, then contact area can be formed, but adjustment tolerances cause scatter in effective contact area size
Solution Approach 1:
The patent combines multiple lithographic steps into a single photolithographic step by using a lift-off technique where a single patterned photoresist layer defines both the contact area opening and the subsequent metal deposition mask, eliminating the need for separate lithographic steps and reducing cumulative tolerance errors
Solution Approach 2:
The patent applies a preliminary protective dielectric layer before the single lithographic step, which is then selectively removed in the contact area region. This preliminary action allows the single photolithographic step to precisely define the contact area without requiring subsequent adjustment steps, thereby improving manufacturing precision while reducing process complexity
2Reliability
If contact area is made larger to compensate for tolerance, then contact area size variation is reduced, but light absorption at contact area increases
Solution Approach 1:
The patent replaces the mechanical approach of enlarging contact areas with a photolithographic precision approach, using a single patterned photoresist layer to define exact contact area boundaries. This substitution of methodology achieves both reliability through precise definition and minimizes light absorption by avoiding unnecessary area enlargement
Solution Approach 2:
The patent changes the critical parameter from contact area size (which would need to be enlarged for tolerance compensation) to photoresist pattern dimensions, which can be controlled with much higher precision. By controlling the photoresist opening size rather than the final metal contact area size, the method achieves reliable contact area definition without increasing light absorption
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 method allows for accurate and reproducible contact area formation, minimizing light absorption and resulting in optoelectronic devices with stable forward voltages and improved light yields, while simplifying the production process and reducing costs.
Implementation Method 1
the photoresist layer is patterned by exposing only the region in which the opening is to be produced
Implementation Method 2
the first layer is partially dissolved away by wet chemical etching
Data Source
AI summary
An optoelectronic device is disclosed. In an embodiment the device includes a semiconductor crystal with a surface having a first lateral region, a second lateral region and a third lateral region, a contact area arranged on the surface in the first lateral region, the contact area comprising a first metal and a first layer including a dielectric arranged on the surface in the third lateral region. The device further includes a second layer having an optically transparent, electrically conductive material arranged on the contact area, the first layer and the second lateral region of the surface and a third layer having a second metal arranged on the second layer.