Semiconductor technology has seen rapid advances in recent years. Complementary?metal-oxide-semiconductor (CMOS) technology is providing tremendous digital processing power by integrating billions of transistors. Indium phosphide (InP) has bridged the terahertz frequency barrier. Gallium nitride (GaN) is offering unprecedented solid-state RF power across the microwave spectrum. Diverse, accessible heterogeneous integration (DAHI) allows engineers to take advantage of all of these advances by combining them along with other semiconductor technologies onto a single chip. DAHI offers the ultimate in RF, mixedsignal, and digital capability for future mobile applications that will demand smaller size and weight with lower power and cost.

The performance, size, weight and power requirements for future systems are increasingly demanding. These can be met by intimate integration of lower power and higher performance scaled CMOS and compound semiconductor technologies into smaller areas and volumes. The more adaptable and more intimate is this integration between two or more technologies, the more flexibility is given to the designer for the selection of the technology for a specific function, or even better, for an optimum combination of different transistor technologies in the same function or cell in the design. Northrop Grumman Aerospace Systems (NGAS) under the Diverse Accessible Heterojunction Integration (DAHI) DARPA program is developing integration processes, design kits and thermal simulation tools to integrate submicron CMOS, InP HBT, GaN HEMT and high-Q passive technologies for advanced DoD systems. We have demonstrated integration of NGAS' InP HBT and GaN HEMT technologies on 65nm and 45nm CMOS wafers.

Northrop Grumman Aerospace Systems (NGAS) under the Diverse Accessible Heterojunction Integration (DAHI) DARPA program is developing heterogeneous integration processes, process design kit (PDK) and thermal analysis tools to integrate deep submicron CMOS, Indium Phosphide (InP) heterojunction bipolar transistors (HBTs), Gallium Nitride (GaN) high electron mobility transistors (HEMTs) and high-Q passive technologies for advanced DoD and other government systems.

GaN on SiC technology has offered tremendous benefits over existing GaAs-based RF technologies. The high breakdown voltage and current handling capability of GaN HEMTs enable a 10x increase in RF power over conventional GaAs- based devices for the same device size. These benefits translate to dramatically improved performance for military and commercial communications, radar and high-power RF systems. However, despite the high thermal conductivity materials and optimized epitaxial profiles already being used, additional improvement of MMIC performance is limited by thermal constraints. Substrate and near channel thermal resistance is a key thermal bottleneck limiting device compaction and junction temperature reduction. NGAS will report on revolutionary methods being developed to directly integrate high quality, high thermal conductivity diamond materials with more than 4x greater thermal conductivity over existing state-of-the-art GaN on SiC HEMT technology. Reducing temperature in the device channel and surrounding regions is critical for reliable operation, supporting additional device compaction and improving circuit performance.

Gallium nitride's (GaN) superior material properties offers revolutionary performance for millimeter wave power amplifiers in terms of output power, power added efficiency, linearity, frequency, bandwidth, gain flatness, and noise. NGAS has developed a 0.2um GaN HEMT technology which demonstrates 3.6 W/mm at 40 GHz with 37% power-added-efficiency (PAE) and 8.4 dB associated gain. RF driven thermally accelerated life testing has demonstrated reliability in excess of 60 million hours median-time-to-failure at 150C junction temperature. At 55 GHz this process has demonstrated 2.8 W/mm at 23% PAE. This capability is 4 - 8 times higher power than competing GaAs HEMT technology.

Under the Compound Semiconductor Materials on Silicon (COSMOS) DARPA program, Northrop Grumman Aerospace Systems (NGAS) has developed an advanced heterogeneous integration technology to intimately integrate compound semiconductor (CS) devices and circuits on CMOS/SiGeBiCMOS wafers. The integration approach is based on a direct face-to-face bonding between pre-fabricated InP chiplets and Si wafers. The heterogeneous integration process is compatible with any semiconductor technology. This integration enables significant improvement in dynamic range and bandwidth of high performance mixed signal circuits. In this paper we describe the integration approach and present two demonstration circuits.

Summary form only given. GaN HEMT technology is transforming applications in communications, radar, and electronic warfare by offering more than 5x higher RF transmit power over the existing GaAs-based technologies. The high breakdown voltage and current handling capability of GaN HEMTs enables, for the same device size, a 10x increase in RF power using GaN-based devices in place of conventional GaAs-based devices. However the ultimate power and performance of GaN technology cannot be exploited in real applications due to thermal limitations on performance and reliability. The high power density in GaN HEMTs translates to mega-Watts/cm 2 heat dissipation at the device gate region. Increasing the heat conductance near the GaN device junction is critical to reduce device junction temperature for reliable operation and performance. NGAS will report on revolutionary methods being developed to directly integrate high quality, high thermal conductivity diamond materials with more than 4x greater thermal conductivity over existing state-of-the-art GaN HEMT technology.

Accelerated temperature lifetesting at Tchannel of 240, 255, and 270°C was performed on 0.1-μm Pt-sunken InP HEMT low-noise amplifiers fabricated on 100 mm InP substrates. The reliability performance was evaluated based on ΔS21 <; -1 dB at 35 GHz. The lifetesting results exhibit activation energy of approximately 1.8 eV and lifetime projection of 99% reliability and 90% confidence exceeds 1 × 108 hours at Tchannel of 125°C. The high reliability demonstration of 0.1-μm Pt-sunken gate InP HEMT low-noise amplifiers on 100 mm InP substrates is essential for advanced military/space applications requiring high reliability performance.

Reliability performance of 0.1-μm Pt-sunken gate InP HEMT MMICs on 4-inch InP substrates was evaluated under elevated temperature life testing. The primary degradation mechanism was observed to be the progressive Schottky junction reaction with the Schottky barrier InAlAs and the InGaAs channel. Despite the progressive Schottky junction reaction with the InAlAs and InGaAs materials, the lifetest at Tambient of 280°C projects the median-time-to-failure exceeding 1×106 hours at Tchannel of 125°C. This result indicates that the promising initial reliability performance was achieved on Pt-sunken gate InP HEMT MMICs on 4-inch InP substrates.

Northrop Grumman Aerospace Systems (NGAS) is developing an Advanced Heterogeneous Integration (AHI) process to integrate III-V semiconductor chiplets on CMOS wafers under the Compound Semiconductor Materials on Silicon (COSMOS) DARPA program. The objective of the program is to have a heterogeneous interconnect pitch and length less than 5 um to enable intimate transistor scale integration. This integration will enable significant improvement in dynamic range and bandwidth of high performance mixed signal circuits.

This letter presents an ultra-wideband low noise amplifier (LNA) using gallium-nitride (GaN) high-electron mobility transistors (HEMT) technology. A -3 dB bandwidth of 1-25 GHz with 13 dB peak power gain is achieved using a modified resistive-feedback topology. To obtain such a wide bandwidth, several bandwidth enhancement techniques are utilized. An inductor connected to the source of the input transistor ensures good input matching (|S11| <; -9 dB) across the entire bandwidth. The shunt feedback loop and the inductive source degeneration minimize all the required inductor values. This GaN HEMT LNA is believed to have the widest bandwidth among all GaN HEMT monolithic microwave integrated circuit (MMIC) LNAs reported to date. With 3.3 dB minimum noise figure (F), 33.5 dBm maximum output-referred third-order intercept point (OIP3), 20 dBm maximum output-referred 1 dB compression point (Output P1 dB), this MMIC amplifier is comparable in performance to distributed amplifiers (DAs) but with significantly lower power consumption and smaller area.

Wafer level bump technology that is compatible to III-V MMIC technology is reported. Two different wafer level bump technologies are presented in the paper. One is solder ball bump and the other is copper bump. Both are fully compatible with existing III-V MMIC backside manufacturing processes. Silicon nitride, deposited at room temperature, is used as solder mask and shows excellent solder blocking capability. UBM (Under-BumpMetallization) materials were specially selected for their solid diffusion barrier characteristics and strong adhesion between bump and MMIC backside metal pad. Bump planarity, shear strength and solderability are extensively characterized, and benchmarked with industry specifications

Northrop Grumman Space Technology (NGST) is developing an Advanced Heterogeneous Integration (AHI) process to integrate III-V semiconductor chiplets on CMOS wafers under the Compound Semiconductor Materials on Silicon (COSMOS) DARPA program. The objective of the program is to have a heterogeneous interconnect pitch and length less than 5 um to enable intimate transistor scale integration. This integration will enable significant improvement in ADC dynamic range and bandwidth

The authors describe a Pd/Ru/Au Ohmic contact with enhanced thermal stability over the more commonly used Pd/Pt/Au Ohmic contact for InAlSb/InAs high electron mobility transistors. Transmission electron microscopy shows that reaction between Pd and the semiconductor begins in samples even before they are annealed. Decreases in contact resistance are correlated with increasing reaction between Pd and the semiconductor for annealing and aging at 175–225 °C for 3 h or 1 week. Small voids form in severely aged samples but do not increase the contact resistance. The Ru diffusion barrier is never observed to react with any other materials in either the contact or the semiconductor, and Au remains isolated from the Pd-bearing reaction products and semiconductor.

We report an advanced InP/InGaAs double heterojunction bipolar transistor technology using aggressive scaling in device layout and epitaxial stack. The device employs a 220Å highly doped base and a 1200Å collector designed to support current densities in excess of 12 mA/µm2. Transistors with emitter width of 0.25-µm have exhibited simultaneous measured ƒT and ƒmax frequencies in the 500 GHz range. Frequency divide-by-two digital circuits designed and fabricated with this InP bipolar technology have demonstrated maximum clock frequency of 172 GHz. Manufacturing capabilities for mixed-signal circuits of increased complexity are also reported with improvements in resolution and bandwidth.

A wafer-level-packaging technology was used to integrate the 0.1 mum AlSb/InAs HEMT low-noise amplifiers with power amplifiers, switches and phase shifters to form a compact tri-stack transmit/receive module for light-weight and ultralow-power applications. The high manufacturability of AlSb/InAs HEMT receivers operating at 0.9 mW was demonstrated on a tri-stack wafer. This demonstration of manufacturable tri-stack transmit/receive modules is essential for phased-array applications requiring light weight and ultralow power.

We report the thermal stability of Pd/Pt/Au Ohmic contacts to InAlSb/InAs high electron mobility transistors. An initial drop in contact resistance correlates with consumption of the InAs electron channel through reaction of both Pd and Pt with the semiconductor heterostructure during a 3 h 175 °C anneal, as determined using transmission electron microscopy. Voids form in the unreacted Pt layer after samples are aged for 1 week at 175 °C, and they grow larger when the samples are aged for 1 week at 200 °C. The contact resistance increases by more than a factor of 2 after samples are aged for 1 week at 225 °C. We discuss the degradation of the contact resistance in light of the interfacial reactions that occur during aging.

This paper reports on multi-decade bandwidth GaN HEMT Cascode-distributed power amplifier designs which achieve performance from base-band to over 20 GHz. The GaN MMICs are based on a 0.2um AlGaN/GaN low noise T-gate HEMT technology with an fT ∼ 75 GHz. To increase the MMIC power capability of this low noise GaN technology, a cascode DA design approach was employed which can operate at twice the recommended Vds voltage. The resulting amplifiers achieve 1–4 Watts of saturated CW power from 100MHz to over 20GHz at an operating voltage of 30V. Typical OIP3 ≫ 40 dBm and NF of 3 dB were also achieved. Compared to equivalent designs in a similar 0.15um GaAs PHEMT low noise technology fabricated in the same foundry, these multi-decade GaN HEMT MMIC DAs obtain 6 dB higher output power and 5.8–6.6dB higher OIP3 while achieving comparable gain, noise figure, and bandwidth. These are believed to be the first multi-decade GaN power distributed amplifiers that have been demonstrated and can enable future ultra-wideband frequency agile and software defined radio systems that require baseband to microwave frequency operation.

Static frequency dividers are widely used technology performance benchmark circuits. Using a 0.25 mum 530 GHz fT I 600 GHz+ fmax InP DHBT process, a static frequency divider circuit has been designed, fabricated, and measured to operate up to 200.6 GHz. The divide-by-2 core flip/flop dissipates 228 mW.