Formation of Cu Substrates with W Addition for Vertical Structure Light Emitting Diodes using Electroplating Method
| Autor: | Sunjung Kim, Luda Lee |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Materials science
Renewable Energy Sustainability and the Environment Metallurgy Substrate (electronics) Condensed Matter Physics Laser Surfaces Coatings and Films Electronic Optical and Magnetic Materials law.invention law Residual stress Electrical resistivity and conductivity Materials Chemistry Electrochemistry Wafer Composite material Electroplating Light-emitting diode Diode |
| Zdroj: | Journal of The Electrochemical Society. 159:D19-D25 |
| ISSN: | 1945-7111 0013-4651 |
| DOI: | 10.1149/2.019201jes |
| Popis: | Pure Cu substrate has been previously electroplated on p-GaN side of vertical structure GaN-based light emitting diode (LED) to mechanically hold thin GaN-based multilayer after removal of a sapphire substrate by laser lift-off process. The ductile Cu substrate needs to be mechanically strengthened to prevent the GaN-based multilayer from being damaged during vertical LED chip fabrication. In this study, the formation of Cu substrate with W addition on Au-seeded LED wafer by electroplating is introduced. W presents as WO 3 in the Cu substrate. W content of W-added Cu deposits was dependent on constant reduction potential in an acidic citrate bath. The reduction potential also influenced directly the electrical resistivity, hardness, and residual stress of W-added Cu substrates. Applying moderate reduction potentials like ―1.1 V resulted in 1.5 times larger hardness than that of pure Cu substrate by adding around 1.0 at % W to Cu. Nevertheless, the electrical resistivity of W-added Cu substrate was maintained as low as that of pure Cu substrate. At more positive reduction potentials tan ―1.1 V, very low residual stress between 4 and 42 MPa was measured. Wafer bowing induced by large residual stress of W-added Cu substrate can cause serious mechanical damage to LED structure. |
| Databáze: | OpenAIRE |
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