Optimization of 1-µm gate length InGaAs-InAlAs pHEMT

Abstract

Purpose The purpose of this study is to demonstrate a pseudomorphic High Electron Mobility Transistor (pHEMT) cutoff frequency (fT) and maximum oscillation frequency (fmax) are determined by the role of its gate length (Lg). Theoretically, to obtain an Lg of 1 µm, the gate’s resist opening must be 1 µm wide. However, after the coat-expose-develop (C-E-D) process, the Lg became 13% larger after metal evaporation. This enlargement is due to both resist thickness and its profile. Design/methodology/approach This research aims to optimize the 1-µm Lg InGaAs-InAlAs pHEMT C-E-D process, where the diluted AZ®nLOF™ 2070 resist with AZ® EBR solvent technique has been used to solve the Lg enlargement problem. The dilution theoretically allows the changing of a resist thickness to different film thickness using the same coating parameters. Here, for getting a new resist, which is simply called AZ 0.5 µm, the experiment’s important parameters such as the coater’s spin speed of 3,000 rpm and soft bake at 110°C for 5 min are executed. Findings The newly mixed AZ 0.5 µm resist has presented a high resolution and undercut profile rather than standard AZ 1 µm resist. Hence, the Lg metallization after using AZ 0.5 µm optimized process showed better results than AZ 1 µm which used the standard process. Originality/value The outcome of the optimization has reached that it is possible to get a nearly sub-µm range gate’s opening using a diluted resist, and at the same time retaining a high resolution and undercut profile.

Reliability, Applications and Challenges of GaN HEMT Technology for Modern Power Devices: A Review

“…In this regard, increasing the Mg electrical activation is one of the most critical factors in improving the threshold voltage V TH of the p-GaN layer for a specific Mg concentration. Adequate growth parameters for the p-GaN layer and annealing conditions may achieve the latter goal [62,63]. On the contrary, because of the high energy of ionization (in the range from 150 to 200 m eV) of Mg as a p-type dopant, i.e., an acceptor, obtaining a high activation of Mg in p-GaN is problematic [64,65].…”

“…In contrast, the metal/p-GaN/AlGaN/GaN system TCAD simulations indicate that on the p-GaN, a Schottky metal gate must have a higher VTH and less leakage than an Ohmic gate [55,63,64]. In the on-state, Meneghini et al [60] demonstrated that a Schottky gate based on WSiN to the p-GaN rather than a typical Ni/Au Ohmic contact could improve In contrast, the metal/p-GaN/AlGaN/GaN system TCAD simulations indicate that on the p-GaN, a Schottky metal gate must have a higher V TH and less leakage than an Ohmic gate [55,63,64].…”

“…In contrast, the metal/p-GaN/AlGaN/GaN system TCAD simulations indicate that on the p-GaN, a Schottky metal gate must have a higher VTH and less leakage than an Ohmic gate [55,63,64]. In the on-state, Meneghini et al [60] demonstrated that a Schottky gate based on WSiN to the p-GaN rather than a typical Ni/Au Ohmic contact could improve In contrast, the metal/p-GaN/AlGaN/GaN system TCAD simulations indicate that on the p-GaN, a Schottky metal gate must have a higher V TH and less leakage than an Ohmic gate [55,63,64]. In the on-state, Meneghini et al [60] demonstrated that a Schottky gate based on WSiN to the p-GaN rather than a typical Ni/Au Ohmic contact could improve the gate voltage swing of a transistor and lower the gate leakage current by roughly four orders of magnitude.…”