Browsing by Author "Liang, Muh-Wang"

Now showing 1 - 2 of 2

InAlAs/InGaAs metamorphic high electron mobility transistor with Cu/Pt/Ti gate and Cu airbridges
(2007-05-01)
Chang, Chun-Wei
;
Chen, Po-Chou
;
Lee, Huang-Ming
;
Chen, Szu-Hung
;
Sahoo, Kartik Chandra
The use of a Cu/Pt/Ti Schottky contact structure and Cu-based airbridges for high-frequency metamorphic high electron mobility transistor (MHEMT) is successfully developed. The material characteristics of the Cu/Pt/Ti Schottky contact on i-InAlAs were studied. Judging from the results of the X-ray diffraction analysis, Auger electron spectroscopy, and transmission electron microscopy, the Cu/Pt/Ti Schottky contact structure on InAlAs was very stable after annealing at 350 degrees C. However, after 400 degrees C annealing, the reaction of copper with the layers underneath started to occur and formed the Cu4Ti phase. The Cu-metallized MHEMT using the proposed Cu/Pt/Ti T-gate structure and Cu-based airbridges has a saturated drain current of 673 mA/mm and a maximum transconductance of 750 mS/mm. The gate to drain breakdown voltage measured was 14.5 V at a gate reverse current of -1 mA/mm. The device also demonstrated a cutoff frequency F-t of 90 GHz and a maximum frequency of oscillation F-max of 165 GHz. An MHEMT with a Au/Pt/Ti gate was fabricated and compared with an MHEMT fabricated with the proposed Cu/Pt/Ti gate. These two kinds of MHEMTs showed similar F-t and F-max. These results demonstrate that the Cu/Pt/Ti T-gate and Cu-based airbridges can be used for MHEMT fabrication with excellent electrical characteristics.
Investigation of electroless cobalt-phosphorous layer and its diffusion barrier properties of Pb-Sn solder
(2006-07-01)
Liang, Muh-Wang
;
Yen, Hui-Ting
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The capability of a cobalt-phosphorous [Co(P)] layer, which was grown via the electroless plating process, to serve as the diffusion barrier of lead-tin (PbSn) solder was investigated in this work. The Auger electron spectroscopy (AES) and energy dispersive spectrometry (EDX) indicated that the phosphorous contents in Co(P) films decrease with increasing film thickness and that the average contents are no less than 8.7 at.% for the specimens prepared in this work. X-ray diffraction in conjunction with composition analyses revealed that the electroless Co(P) layer was a mixture of amorphous and nanocrystalline structures; however, the AES depth profile and subsequent analyses indicated that the first-formed Co(P) layer should be amorphous because it contains as much as 18 at.% P. This implied a good barrier capability for electroless Co(P) because, as revealed by EDX line scan, the Sn and Cu atoms could not penetrate the Co(P) layer after the PbSn/Cu/Co(P)/Cu/Ti/Si sample was subjected to annealing at 250 degrees C in a forming gas ambient for 24 h. The fact that Sn and Cu underlayers could not penetrate the Co layer after such a liquid-state annealing step was evidence that the Co(P) layer may simultaneously serve as a diffusion-barrier interlayer dielectric and as an under-bump metallization for flip-chip copper (Cu) ICs.