Abstract

We have demonstrated that SiC mesastructures with gently sloping sidewalls form with the help of selective reactive ion etching (RIE) of silicon carbide through a photoresist mask (slanted walls are formed during simultaneous etching of SiC and the resistive mask with the edge in the shape of a sharp wedge). A simple geometrical model of etching predicts that the resultant slope of the mesastructure wall must be specified by two parameters, i.e., initial angle of the resistive wedge and the selectivity of SiC etching relative to the photoresist (ratio of etching rates of SiC and photoresist). For experiments, we used polished 4H–SiC wafers with the (0001) orientation. Photoresist regions with an edge angle of 22° were deposited using photolithography onto the Si side of the wafers. Then etching of mesastructures was performed in nitrogen trifluoride in a setup with an inductively coupled plasma. We selected RIE parameters ensuring SiC and photoresist etching with rates of 55 and 160 nm/min, respectively (etching selectivity was 1 : 3). The SiC mesastructures formed by etching have a height of 3.2 μm and gently sloping sidewalls with a slope of about 8°. This technology can be used for preparing high-voltage SiC devices with a straight bevel.

中文翻译：

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通过光致抗蚀剂掩模的干法选择性刻蚀来形成具有轻微倾斜侧壁的SiC台面结构

摘要

我们已经证明，借助于光致抗蚀剂掩模对碳化硅进行选择性反应离子刻蚀（RIE）的帮助下，形成了具有缓慢倾斜侧壁的SiC台面结构（在同时腐蚀SiC和电阻性掩模的过程中形成了倾斜的壁，其边缘呈C形）尖锐的楔子）。一个简单的蚀刻几何模型预测，必须通过两个参数来指定台面结构壁的合成斜率，即电阻楔的初始角度和SiC蚀刻相对于光刻胶的选择性（SiC和光刻胶的蚀刻速率之比） 。对于实验，我们使用抛光的4 H–（0001）取向的SiC晶片。使用光刻将具有22°边缘角的光致抗蚀剂区域沉积到晶片的Si侧。然后在具有感应耦合等离子体的装置中在三氟化氮中执行台面结构的蚀刻。我们选择了RIE参数，以确保分别以55和160 nm / min的速率蚀刻SiC和光致抗蚀剂（蚀刻选择性为1：3）。通过蚀刻形成的SiC台面结构具有3.2μm的高度，并且以大约8°的斜率缓慢地倾斜侧壁。该技术可用于制备具有直斜角的高压SiC器件。