高功率碳化矽金氧半場效電晶體之元件結構與應用之探討

Abstract

基本上功率電晶體是含有數微米了磊晶矽耐壓區及垂直式的元件結構，在傳統的雙擴散金氧半功率電晶體，由於在平面通道元件密度及導通阻抗有其極限，未達高元件密度與低阻抗的要求，往往限制了傳統雙擴散功率的電晶體的表現。溝槽式閘極高功率金氧半場效電晶體雖有助於改善導通阻抗以增進元件密度，然在溝槽底部卻需要考慮尖端電場的問題，限制了最大操作電壓。在此嘗試提出一個高功率碳化矽增強型電晶體結構將有助於改善傳統功率元件的缺點。

由於以矽為基底的功率電晶體在操作電壓及導通電阻的受限，因碳化矽本身優越的物質特性，碳化矽功率電晶體逐漸為人所用，本篇論文首先強調碳化矽在高功率元件元件應用的優勢，引用正確的模型與參數的修正。以期能對不同結構下的高功率元件所比較的結果做一精確的分析，藉著討論傳統溝槽式及雙擴散式功率電晶體所面臨的閘極氧化層崩潰及夾止效應，提出一個新式的改良結構，並以MEDICI模擬軟體討論參數的最佳化，並與傳統結構的電晶體做比較，證明其優越的性質。

The basic structure of power MOSFET consists of an epitaxial layer for voltage blocking and a drain electrode at the substrate contact. In the conventional double diffused MOSFET, the poor channel resistance and JFET effect limited the DIMOS performance. The trench gate MOSFET, have a much improved on-resistance and packing density because of its vertical channel, however, a high local electric field at the trench corner is of critical importance to the performance of the device. A innovative structure of SiC accumulation-mode MOSFET designed to improve the performance of conventional structure of power MOSFET.

This thesis focused on the design of high voltage MOSFET on SiC power devices. Parameter extraction for 4H-SiC MOS devices is the main focus for this thesis, which includes the mobility parameter extraction. Detailed analysis of the important design parameters of the innovative structure is performed using MEDICI with the parameter been used in calibration process.