TSMC patent application published on compound device with GaN structures
The US Patent and Trademark Office (USPTO) has published a TSMC patent application for making a compound semiconductor device with GaN structures. It is listed under publication number 20140203288.
GaN is used to form various integrated circuit devices including high power FETs, MISFETs, high frequency transistors, and HEMTs. In a conventional semiconductor device, gate structures are formed using fluoride-based plasma treatment techniques; however, such techniques suffer control issues for a device having plural enhanced mode (E-mode) or depletion mode (D-mode) transistors or devices on the respective circuit. Therefore, a compound semiconductor gate structure and method of forming such a gate structure are needed.
In this patent, the semiconductor structure includes a buffer layer on a substrate, a graded AlGaN layer disposed on the buffer layer, a GaN layer disposed on the graded AlGaN layer, a second AlGaN layer disposed on the GaN layer and a gate stack disposed on the second AlGaN layer.
The gate stack includes one or more of a III-V compound p-doped layer, a III-V compound n-doped layer, an aluminum nitride layer between the III-V compound p-doped and n-doped layers, and a metal layer formed over the p-doped, AlN, and n-doped layers. A dielectric layer can also underlie the metal layer
