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CN-122029969-A - Semiconductor device including micro LED structure

CN122029969ACN 122029969 ACN122029969 ACN 122029969ACN-122029969-A

Abstract

The proposed solution relates to a semiconductor device (30) comprising an epitaxial wafer (10) and a plurality of InGaN platelets (100), each grown monolithically on the epitaxial wafer and configured with a top c-plane surface. The upper mask layer (200) is provided with a mask aperture (220) over the InGaN platelet, wherein the width of the mask aperture is smaller than the top c-plane surface. A plurality of micro LED structures (240) including Quantum Well (QW) layers (242) are grown on the top c-plane surface in one of the mask apertures. The solution also relates to a micro LED device (500) comprising the semiconductor device, and to a method for manufacturing the semiconductor device.

Inventors

  • M. Bjork
  • M. Hellin
  • L. Samuelson

Assignees

  • 六边钻公司

Dates

Publication Date
20260512
Application Date
20241001
Priority Date
20231130

Claims (20)

  1. 1. A semiconductor device (30), comprising: an epitaxial wafer (10); A plurality of InGaN platelets (100), each InGaN platelet monolithically grown on an epitaxial wafer and configured with a top c-plane surface (110); An upper mask layer (200) having a mask aperture (220) over InGaN platelets, wherein the width of the mask aperture is smaller than the top c-plane surface; A plurality of micro LED structures (240) comprising quantum well QW layers (242), wherein each micro LED structure is grown on a top c-plane surface in one of the mask apertures.
  2. 2. The semiconductor device of claim 1, wherein each micro LED structure further comprises a top InGaN layer (243) grown on the respective QW layer.
  3. 3. The semiconductor device of claim 1 or 2, wherein a single mask aperture is configured over each InGaN die, wherein a single micro LED is configured on each InGaN die.
  4. 4. The semiconductor device of any preceding claim, wherein a plurality of mask apertures (221, 222, 223) are configured over each InGaN die, wherein a plurality of micro LED structures (230, 240, 250) are configured on each InGaN die.
  5. 5. The semiconductor device of claim 4, wherein three mask apertures are disposed over each InGaN die, wherein respective micro LED structures for red, green, and blue emission are disposed on each InGaN die.
  6. 6. A semiconductor device according to any preceding claim, wherein the aperture width is related to the emission wavelength from the respective micro LED structure.
  7. 7. A semiconductor device according to any preceding claim, wherein the apertures are configured to have increasing widths in the order red-green-blue for different emission wavelengths of the respective micro LED structure.
  8. 8. A semiconductor device according to any preceding claim, wherein each micro LED structure comprises an InGaN surface layer (241) grown in a mask aperture above a top c-plane, wherein a QW layer is grown on the InGaN surface layer.
  9. 9. The semiconductor device of claim 8, wherein an indium concentration of the InGaN surface layer decreases with increasing opening width.
  10. 10. A semiconductor device according to any preceding claim, wherein the epitaxial wafer comprises a lower mask layer having a mask opening in which a grown InGaN platelet is disposed.
  11. 11. A semiconductor device according to any preceding claim, wherein the top c-plane surface has a hexagonal footprint.
  12. 12. A semiconductor device according to any preceding claim, wherein the mask aperture has a substantially circular footprint.
  13. 13. A semiconductor device according to any preceding claim, wherein each micro LED structure has a truncated pyramid shape terminating in a c-plane connector surface.
  14. 14. A micro LED device (500), comprising: A semiconductor device according to any preceding claim, and A driver circuit (54) connected to a respective top portion of each micro LED structure by a p-contact and to the substrate side of the epitaxial wafer by an n-contact for generating light emission from the respective micro LED structure.
  15. 15. The micro LED device of claim 14, wherein the driver circuit is connected to a plurality of micro LED structures configured on the same InGaN die through separate p-contacts.
  16. 16. A method of fabricating a semiconductor structure, comprising: forming monolithically grown InGaN platelets on an epitaxial wafer, wherein each InGaN platelet has a top c-plane surface; Disposing a mask layer over the InGaN platelet; Forming a mask aperture in the upper mask above the top c-plane surface, wherein the aperture has a width less than the width of the top c-plane surface, and Micro LED structures including quantum well QW layers over the top c-plane surface are grown from each mask aperture.
  17. 17. The method of claim 16, further comprising: a top InGaN layer of the corresponding micro LED structure is grown on the corresponding QW layer.
  18. 18. The method of claim 16 or 17, wherein forming InGaN platelets comprises: epitaxially growing InGaN pyramids by mask opening growth in a lower mask layer on an epitaxial wafer, and The InGaN pyramid is truncated to form a c-plane top surface.
  19. 19. The method of any of claims 16-18, wherein forming mask apertures comprises forming apertures having different widths, wherein the growth configuration of the QW layer has micro LED structures of different emission wavelengths.
  20. 20. The method of any of claims 16-19, further comprising: an InGaN surface layer is grown in the mask aperture above the top c-plane, with a QW layer grown on the InGaN surface layer.

Description

Semiconductor device including micro LED structure Technical Field The technology relates to the field of semiconductor devices, in particular micro LEDs (micro light emitting diodes) for use in display and lighting applications. This field is directed to improving the efficiency, performance and manufacturing process of micro LEDs. The proposed solution relates in particular to such a semiconductor device configured to obtain a controlled emission wavelength and to a method of manufacturing the same. Background Micro LEDs have become a promising technology for high resolution displays in various applications such as Augmented Reality (AR), virtual Reality (VR), mixed Reality (MR), smartwatches, and heads-up displays (HUD). These applications require small pixel sizes (typically below 10 μm) to achieve high resolution and compact form factors. The use of micro LEDs provides several advantages over competing technologies such as Liquid Crystal Displays (LCDs) and Organic Light Emitting Diodes (OLEDs), including higher brightness, longer lifetime, and lower power consumption. However, there are some challenges associated with the fabrication and performance of micro LEDs at small pixel sizes. An important issue is the dramatic loss of external quantum efficiency as the pixel size decreases. This efficiency loss is mainly due to an increase in the influence of sidewall damage caused by dry etching. Therefore, developing efficient micro LEDs with pixel sizes less than 10 μm remains a challenge. Another problem is a red-emitting micro LED, where both nitride micro LEDs and AlInGaP micro LEDs are unsatisfactory in terms of efficiency or brightness. Another challenge in making micro LEDs is assembling red, green, blue (RGB) pixels for high resolution displays. Currently, these three colors are fabricated on separate wafers using epitaxial methods and need to be picked from these wafers and placed on the back plate/driver circuit of the display to create an array of RGB pixels. There are various techniques to achieve this, many of which are not yet technically mature. To date, no pick and place method has been successfully used in production to assemble displays with pixel sizes less than 10 μm. For small displays (e.g., AR/VR/MR, smartwatch, etc.), it is possible to bond the LED die directly to the Si CMOS active drive circuitry. This still requires the assembly of all three colors into RGB pixels. For pixel sizes above 10 μm this can be achieved by several methods including pick and place methods, mechanical stacking of all three color sources on top of each other, or multi-junction epitaxial layers connected during epitaxy via e.g. tunnel junctions. However, these methods are not suitable for pixel sizes below 10 μm. Several methods have been proposed to address these challenges, such as growing red, green, and blue LEDs directly on the same epitaxial wafer (i.e., semiconductor wafer with a common growth layer), so that pick and place mass transfer can be avoided and single-step wafer bonding can be used instead to attach the LEDs to CMOS chips. However, there is still a lack of technology to realize RGB epitaxial wafers with pixel sizes below 10 μm and as small as below 1 μm, where the external quantum efficiency is in the two-digit range for all three colors, and to obtain controlled emission wavelengths. Disclosure of Invention The proposed solution relates to a device and a method as outlined in the independent claims. Further aspects and features are summarized below and set forth at least in part in the dependent claims. According to a first aspect of the present disclosure, a semiconductor device is provided. The semiconductor device includes an epitaxial wafer and a plurality of InGaN platelets (platelets), each grown monolithically on the epitaxial wafer and configured with a top c-plane surface. The upper mask layer is provided with a mask aperture over the InGaN platelet, wherein the width of the mask aperture is smaller than the top c-plane surface. Comprising a plurality of micro LED structures, wherein each micro LED structure comprises a Quantum Well (QW) layer, wherein each micro LED structure is grown on a top c-plane surface in one of the mask apertures. According to a second aspect, there is provided a micro LED device comprising the semiconductor device according to the first aspect and a driver circuit. The driver circuit is connected to a respective top portion of each micro LED structure by a p-contact and to the substrate side of the epitaxial wafer by an n-contact for generating light emission from the respective micro LED structure. According to a third aspect, there is provided a method of fabricating a semiconductor device, comprising: forming monolithically grown InGaN platelets on an epitaxial wafer, wherein each InGaN platelet has a top c-plane surface; Disposing a mask layer over the truncated InGaN platelets; Forming a mask aperture in the upper mask above the top c-plane surface