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leds with stress buffer layer under metallization layer

A technology of stress buffer layer and metal contact layer, which is applied in the direction of semiconductor devices, electrical components, circuits, etc., can solve problems such as difficulty in obtaining flat soldering pads, achieve the best overall performance, reduce manufacturing costs, and improve reliability.

Active Publication Date: 2021-03-12
LUMILEDS HLDG BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore it is difficult to obtain a flat solder pad of uniform thickness

Method used

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  • leds with stress buffer layer under metallization layer
  • leds with stress buffer layer under metallization layer
  • leds with stress buffer layer under metallization layer

Examples

Experimental program
Comparison scheme
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Embodiment Construction

[0017] Figure 1-8 A wafer level process flow is illustrated in accordance with one embodiment of the invention. For simplicity, only a single LED area on a much larger wafer is shown. Each step shown for the illustrated LED area applies to all LED areas on a large wafer.

[0018] refer to figure 1 , the process flow for creating a wafer of LEDs begins with a patterned sapphire substrate (PSS) 10 . The substrate 10 will typically have a disc shape and be substantially transparent to the light emitted by the LED. A surface 12 is roughened (patterned), such as by grinding, "sand blasting," chemical etching, plasma etching, or other roughening process. Roughening improves light extraction by reducing total internal reflection (TIR). The surface 12 of the substrate 10 may be patterned in any ordered or random manner to improve light extraction.

[0019] After removal of the sapphire substrate, roughening of the semiconductor layer light-emitting surface of conventional flip-...

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PUM

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Abstract

A semiconductor LED layer is grown epitaxially on the patterned surface of the sapphire substrate (10). The patterned surface improves light extraction. LED layers include p-type layers and n-type layers. The LED layer is etched to expose the n-type layer. One or more first metal layers are patterned to electrically contact the p-type layer and the n-type layer to form p-metal contacts (32) and n-metal contacts (33). A dielectric polymer stress buffer layer (36) is spin-coated over the first metal layer to form a substantially planar surface over the first metal layer. The stress buffer layer has openings exposing the p-metal contact and the n-metal contact. Metal pads (44, 45) are formed over the stress buffer layer and electrically contact the p-metal contact and the n-metal contact through the opening in the stress buffer layer. The stress buffer layer acts as a buffer to accommodate the difference in CTE of the solder pad and the underlying layer.

Description

technical field [0001] The present invention relates to packaging light emitting diodes (LEDs), and in particular to stress buffer layers between LED semiconductor layers and solder pad metallization layers. Background technique [0002] Thin film flip chip (TFFC) LEDs have anode and cathode contacts on the bottom surface, opposite the light emitting surface. Thus, such TFFC LEDs use the entire top die area surface for light output, since topside (light output side) metallization for wire bonding is unnecessary. However, in the case of TFFC LEDs, a die-level process including sapphire substrate lift-off (for GaN-based LEDs) and epitaxial layer (EPI) roughening (to improve light extraction) is typically used, which substantially increases packaging costs. It would be beneficial to not require removal of the sapphire substrate while still achieving good light output extraction. [0003] Conventional TFFC LEDs have a rigid dielectric layer formed on the LED semiconductor laye...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L33/44H01L33/48
CPCH01L33/44H01L33/486H01L33/0066H01L33/62H01L2933/0016H01L2933/0025H01L2933/0066H01L33/0093
Inventor S.阿克拉姆Q.邹
Owner LUMILEDS HLDG BV