Microcontact Printing Polychromatizing Layer for LED Uniformity
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Solution Overview
Problem
Conventional methods for applying polychromatizing layers to semiconductor substrates result in inhomogeneous layer thickness and color variation in light-emitting diodes, leading to inconsistent emission spectra and significant material loss.
Innovation Solution
A microcontact printing process is used to apply a polychromatizing layer with precise control over layer thickness and structure, ensuring uniformity and reducing material loss by using a printing stamp with a cavity that accommodates and delivers luminescent material directly to the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If spin coating or spin coating methods are used to apply polychromatizing layer, then the entire surface of semiconductor wafer can be covered, but layer thickness becomes inhomogeneous and material loss increases
Solution Approach 1:
The printing stamp is divided into multiple printing elements (cylindrical and conical sections) that can be independently controlled. Each printing element deposits material in a controlled manner, allowing the entire wafer surface to be covered while maintaining homogeneous layer thickness through precise control of each segment's deposition process
Solution Approach 2:
The conventional spin coating mechanical system is replaced with a printing-based system. Instead of relying on centrifugal force and manual manipulation, the patent uses a automated printing stamp that precisely controls material deposition through mechanical contact, eliminating the inhomogeneity caused by spin coating while maintaining full surface coverage
2Area of stationary object
If spin coating or spin coating methods are used to apply polychromatizing layer, then the entire surface of semiconductor wafer can be covered, but material loss increases significantly
Solution Approach 1:
The printing stamp is designed to hold and deliver the exact amount of luminescent material needed for each wafer. The stamp's cavities are filled with material, and the printing process transfers only the required quantity directly to the substrate, eliminating the excessive material application and subsequent waste associated with spin coating methods
Solution Approach 2:
The printing stamp can be refilled with luminescent material after each printing cycle. Instead of discarding unused material from spin coating, the system recovers and reuses the material stored in the stamp cavities, significantly reducing overall material loss while maintaining full wafer surface coverage
3Ease of manufacture
If conventional coating methods are used, then polychromatizing layer can be applied to substrate, but color variation and binning occur due to inhomogeneous layer thickness
Solution Approach 1:
The manual spin coating process is replaced with an automated printing system. The printing stamp mechanically controls material deposition with high precision, ensuring uniform layer thickness across the entire wafer surface. This eliminates the color variation and binning problems while maintaining ease of manufacture through automated processing
Solution Approach 2:
The printing stamp applies luminescent material with locally controlled precision. Each printing element on the stamp can be optimized to deposit material uniformly in its specific region, ensuring that every local area of the wafer receives the correct layer thickness. This local quality control eliminates color variation while keeping the overall process simple and manufacturable
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 method achieves highly homogeneous layer thickness and color spectra across light-emitting diodes, minimizing intensity peak shifts and material loss, thereby eliminating binning and enhancing material efficiency.
Implementation Method 1
The light conversion material is used to convert the light emitted from the sublayer with respect to its wavelength. This light is incident on the light conversion material which converts the wavelength of the original light to another wavelength. Depending partially on which mechanism exactly underlies the conversion of the wavelength, the light conversion material is called a luminescent material, a photoluminescing material, a fluorescent dye or simply a phosphor.
Implementation Method 2
Here, the polychromatizing layer is applied with a printing process. A printing stamp (5) has a structure (6) which is placed in a printing cavity (7o). The stamp (5) is provided with a dispersion in which particles of luminescent material are dispersed such that elevations (7) are wetted with a film (8) of this dispersion.
Data Source
AI summary
The invention relates to a method for applying a polychromatizing layer which contains at least one luminescent means on a semiconductor substrate, which layer is suitable for producing a monochromatic light. The polychromatizing layer is applied with a printing process, especially with a micro-contact printing process. Preferably the polychromatizing layer is applied structured.