Laser Patterning Vertical Solid State Devices Using Dual Masking Layers
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Solution Overview
Problem
Current etching processes for vertical solid state devices, such as LEDs, utilize toxic gases and expensive methods, necessitating the development of patterning techniques that are cost-effective and gas-free, while also being compatible with various materials and processing steps.
Innovation Solution
A patterning process using masking layers, where a dielectric layer acts as an absorbing mask and a reflective mask comprising Ni/Ti/Au/Ag is used in conjunction with a laser to pattern epitaxial or device layers, allowing for precise etching without toxic gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional etching processes are used for patterning device layers, then etching can be performed, but toxic gases are consumed and process cost increases
Solution Approach 1:
The patent replaces chemical etching processes with laser-based patterning. The laser beam directly patterns the device layers through ablation or selective heating, eliminating the need for toxic etching gases and chemical baths. This substitution of chemical mechanisms with optical/thermal mechanisms resolves the contradiction by maintaining patterning capability while removing harmful substance consumption.
Solution Approach 2:
The patent changes the fundamental parameter of the patterning process from chemical reaction-based to energy-based (laser). By controlling laser parameters such as wavelength, pulse duration, and intensity, the process achieves precise patterning without consuming toxic gases. This parameter change enables the same functional outcome (patterning) through a different physical mechanism that avoids the harmful side effects.
2Ease of manufacture
If conventional etching processes are used for patterning device layers, then etching can be performed, but process cost increases
Solution Approach 1:
The laser-based patterning system replaces expensive conventional etching equipment and consumables. By using a laser source with appropriate masking layers, the process eliminates costs associated with toxic gases, chemical baths, and specialized etching tooling. The masking layers (reflective and absorbing) are inexpensive materials that can be deposited using standard thin-film techniques, significantly reducing overall process cost.
Solution Approach 2:
The patent employs disposable masking layers (reflective mask and absorbing mask) that are deposited on the device layers, used for patterning, and then removed. These masking layers serve as single-use protective elements that enable the laser process while being inexpensive compared to the toxic gases and specialized equipment required by conventional etching methods.
3Device complexity
If a single masking layer is used for laser patterning, then process simplicity is maintained, but patterning precision and material compatibility are insufficient
Solution Approach 1:
The patent divides the masking function into two separate layers: a reflective masking layer and an absorbing masking layer. Each layer performs a specific function - the reflective layer prevents laser damage to underlying structures by reflecting the laser beam, while the absorbing layer enables precise patterning through selective laser absorption. This segmentation of the masking function into specialized sub-layers achieves superior patterning precision while maintaining reasonable process complexity.
Solution Approach 2:
Different regions of the device structure receive different types of masking protection tailored to their specific requirements. The reflective mask is applied where laser reflection is needed to prevent damage, while the absorbing mask is applied where laser absorption for patterning is desired. This local differentiation of masking quality enables precise control over the patterning process and material compatibility.
4Productivity
If laser patterning without masking layers is used, then process steps are reduced, but selective patterning and material protection are insufficient
Solution Approach 1:
The patent applies masking layers to the device layers before laser patterning. The reflective mask is deposited first to establish the basic pattern structure, followed by the absorbing mask for precise laser patterning. This preliminary preparation of the masking structure enables the laser process to proceed efficiently with high reliability, as the masks are already in place to provide selective protection and patterning guidance.
Solution Approach 2:
The masking layers serve as intermediaries between the laser beam and the device layers. Rather than applying laser energy directly to the device layers (which would lack selectivity and control), the masking layers mediate the interaction by selectively absorbing or reflecting the laser energy. This intermediary approach enables precise patterning while protecting sensitive device structures from direct laser exposure.
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 reduces costs and environmental impact by enabling efficient patterning of device layers using a laser with masking layers, ensuring compatibility with different materials and processing steps, thereby enhancing process optimization and device fabrication.
Implementation Method 1
a dielectric layer acting as an absorbing mask to prevent the laser heating the device layers
Implementation Method 2
a reflective mask comprising Ni/Ti/Au/Ag deposited on the device layers to reflect the laser
Implementation Method 3
The masking layers can be used with laser beams to expose light and pattern the device layers
Data Source
AI summary
Devices and methods for patterning the vertical solid state devices are provided. In some examples, a method of fabricating micro devices comprising forming device layers on a substrate, forming a first masking layer on a top layer of the device layers, forming a second masking layer on the first masking layer; and etching the device layers using the first and second masking layers to pattern the device layers.