Self-Aligned Contact Metallization to AlGaN/GaN Heterostructures
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2017 IEEE. Nitride device scaling and large scale integration requires the increased manufacturability of self-aligned processes. To date, excellent contacts to GaN heterostructures with 2DEG are achieved through lithographically-defined metallization [1], despite the so-called self-aligned regrowth processes used [2,3]. We have developed a novel self-aligned contact metallization process using Titanium to make ohmic contacts (RC = 0.36 -mm) to AlGaN/GaN hetero-structures. After metal selection experiments, the field dielectric, selective wet etch chemistry, surface pre-treatment and ohmic anneal are engineered to realize the salicide-like process. A CHF3+O2 surface pre-treatment is found to be vital to implementation of the self-aligned contact. Gate-last transistor devices demonstrate the feasibility of the unique process module. These results demonstrate the first truly self-aligned contact module for AlGaN/GaN 2DEG devices.
