氮化鎵金氧半場效電晶體之製程及特性研究

Abstract

在光電上普遍應用的高能帶半導體氮化鎵，在高功率以及高溫元件上具有相當的潛力。目前為止在氮化鎵電子元件的製作上仍有許多的困難以及挑戰。本論文中我們提出一種新的介電質作為氮化鎵金氧半場效電晶體的閘極氧化層，在攝氏三百度下以電子迴旋共振化學氣相沉積出的氮化矽，具有折射係數介於 1.95~2.0之間以及介面狀態密度也低於3.1x1011cm-2eV-1，而崩潰電壓則在11.6MV/cm之上等特質。至於p型金氧半場效電晶體，在快速熱退火爐管中其最佳的合金溫度為攝氏五百九十度，其接觸電阻在攝氏三百度下可達10-3 Ωcm2

The wide bandgap semiconductor GaN, which has commonly used in the optical applications, is considered to have potentials in the high power and high temperature electron device applications. There are still many challenges for the fabrication of GaN-based electron device. In this thesis, we propose a new gate dielectric for use in the GaN-based MISFETs. SiN was deposited at 300oC as the insulating layer of a GaN-based MISFET by using electron cyclotron chemical vapor deposition (ECR-CVD) with SiH4/N2 gas flow ratio of 7/43. The deposited film had the refractive index of 1.95~2.0 at the wavelength of 400nm~700nm and relative dielectric constant of 6. The interface state densities of the SiN film were less than 3.1x1011cm-2eV-1 around the midgap and the breakdown field was higher than 11.6MV/cm. The p-type depletion mode MISFET was also demonstrated. The optimum annealing temperature was 590oC by using the RTA, and the contact resistance could be achieved in the order of 10-3 Ωcm2 at 300oC.