Novel Radio Frequency Conductor with Improved Conductivity for Ultra-low-power Wireless Applications

TO-102 • PT 1.2610 • As of 10/2023
Ernst Ruska-Centre
Materials Science and Technology (ER-C-2)

Technology

Our technology addresses both the optimisation of electrode forms for high frequency device operation as well as innovative solutions for their preparation.

Problem addressed

Conventionally used T-gate structures are essential for radio frequency (RF) transistors to reduce gate resistance. This is one of the most effective methods to improve the device maximum oscillation frequency (fmax). However, further innovative solutions are called for to reduce Skin-effect losses and improve device performance as the structure sizes diminish and the operation frequencies of the devices become even higher. We therefore developed innovative gate preparation solutions to optimize electrode forms for high frequency device operation. The approach leads to an increase in electrode surface area whilst the volume of the conductive material (usually gold) is minimised.

Solution

The new gate forms developed at Forschungszentrum Jülich GmbH are produced by means of a standardised photolithographic process. The conventionally used lithographical techniques and other technological steps for gate definition are circumvented. For metallisation, two materials with metallic conductivity but with different reactivity are employed. Photolithographical methods followed by wet chemical etching are carried out. The approach is scalable and allows for alternative spatial T-gate structures. The innovative technology was applied to form a new double-level-T-gate structure (DLTG) on high electron mobility (HEMT) transistor structures. The total cross-section of the double-level-T-gate contributing to the current transport is about two times higher than for a standard T-gate design (see figure), resulting in halving the gate resistance.

The new layout reduces the skin effect related deterioration of the transistor properties. The conductivity is increased at lower material costs and high-frequency characteristics are improved.

Potential Use

The technology is suitable for various applications: high frequency components such as high frequency transistors (e.g., HEMTs) for integrated mm-wave circuits for ultra-low-power wireless applications, mm-wave radar for space applications, terahertz bands for indoor wireless, localisation studios and gigabyte WiFi-networks.

Development Status and Next Steps

Forschungszentrum Jülich has extensive expertise in this field. Proof of principle has been shown. Experimental data is available and demonstrates the efficiency of the double-level-T-gate. The shape of the gate needs to be adjusted to different applications. The Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons – Materials Science and Technology (ER-C-2) – already cooperates with numerous national and international companies and scientific partners. Forschungszentrum Jülich focuses on energy and cost-efficient devices, suitable for various emerging technologies. We are continuously seeking for cooperation partners and/or licensees in this and adjacent areas of research and applications.

More technologies