平面通道的結構使得單元間距(cell pitch)不容易縮小,相鄰的p型基體(P-body or P-base)造成的接面場效應電晶體(JFET)效應也會增加導通電阻。UMOSFET的單元間距在相同的製程水準下,大約是VDMOSFET的60%,而且理想上可以消除JFET效應,得到較低的導通電阻。但是UMOSFET的製程比VDMOSFET困難,溝槽蝕刻製程以及溝槽側壁的閘極氧化製程,都需要精準控制。特別是為了降低溝槽底部的電場,需要增加很多製程步驟,例如Rohm採用雙溝槽結構,如圖7(a)所示;Infineon採用不對稱的溝槽結構,如圖7(b)所示;或是在溝槽底部增加P+屏蔽層,如圖7(c)所示。然而這些作法除了增加製程成本,也會產生JFET效應。
2021年1月,清華大學黃智方教授(半導體射月計畫成果)在IEEE Electron Device Letters率先發表800V橫向LDMOSFET和低壓CMOS單晶片整合,如圖12所示。日本的AIST則在同年的ISPSD研討會發表單晶片整合1200V等級的溝槽式閘極MOSFET以及CMOS閘極驅動電路成果,是首度整合低壓CMOS和垂直式的功率元件,如圖13所示。
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