METHOD FOR INCREASING AN OXIDE THICKNESS AT TRENCH CORNER OF AN U-SHAPED GATE METAL-OXIDE-SEMICONDUCTOR FIELD-EFFECT TRANSISTOR

專利類型

發明

專利國別 (專利申請國家)

美國

專利申請案號

17/161,951

專利證號

US 11,538,920 B2

專利獲證名稱

METHOD FOR INCREASING AN OXIDE THICKNESS AT TRENCH CORNER OF AN U-SHAPED GATE METAL-OXIDE-SEMICONDUCTOR FIELD-EFFECT TRANSISTOR

專利所屬機關 (申請機關)

國立交通大學

獲證日期

2022/12/27

技術說明

一種增加溝槽式閘極功率金氧半場效電晶體之溝槽轉角氧化層厚度的製造方法，其係提供一N型半導體基板，在其中形成N型漂移區、N型重摻雜區、P型重摻雜區、P型基底區，利用微影蝕刻定義出溝槽區域，並以熱氧化或沉積沿著溝槽形成墊層氧化層。一氧化障礙層係覆蓋於墊層氧化層上，通過一熱氧化製程，使溝槽轉角處氧化生成明顯的轉角氧化層。在去除墊層氧化層與氧化障礙層後，可接續進行後端製程，完成電晶體結構。本發明可實現溝槽側壁底部氧化層增厚的目的，且可應用於碳化矽等高壓元件，有效解決溝槽轉角處電場集中效應，提高元件耐壓。 A method for increasing an oxide thickness at trench corner of an UMOSFET is provided, comprising providing an N-type substrate, and forming an N-type drift region, N-type heavily doped region, P-type heavily doped region and P-type body therein. A trench is defined through lithography, and an underlayer oxide is formed along the trench through oxidation or deposition process. An oxidation barrier is formed upon the underlayer oxide. A thermal oxidation process is then employed such that a corner oxide is effectively formed at the trench corner. After removing the underlayer oxide and the oxidation barrier, a plurality of back-end processes can be carried out to complete the transistor structure. The invention is aimed to increase the oxide thickness near the trench bottom, and can be applied to high voltage devices, such as SiC. The conventional electric field concentration effect occurring at the trench corner is greatly solved, thus increasing breakdown voltages thereof.

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