ALD HfO₂ and Al₂O₃ as MIM Capacitor Dielectric for GaAs HBT Technology

Abstract

Hafnium dioxide (HfO2) and aluminum oxide (Al2O3) films have been deposited using atomic layer deposition (ALD) method and have been evaluated and used as metal-insulator-metal (MIM) capacitor dielectric in GaAs hetero-junction bipolar transistor (HBT) technology. The results show that the capacitor with 62 nm of ALD HfO2 resulted in a capacitance density of 2.73 fF/mm2, while that with 59 nm of ALD Al2O3 resulted in a capacitance density of 1.55 fF/mm2. This capacitance density increased, when the temperature was increased from 25 to 150oC. There was no significant change in capacitance density of these ALD films, when the applied voltage was varied from -5 to +5 V and when the frequency was increased from 1 kHz to 1 MHz. The breakdown voltage of the ALD hafnium dioxide and aluminum oxide films was measured to be at 34 V and 41 V, respectively. As the temperature was increased from 25 to 150oC, the breakdown voltage of both films decreased, while the leakage current increased. These results show that both ALD HfO2 and Al2O3 are compatible with, and suitable as MIM capacitor dielectric in GaAs HBT technology and can be adjusted to meet the specific application and requirements of the GaAs devices and designs.

Review—Silicon Nitride and Silicon Nitride-Rich Thin Film Technologies: Trends in Deposition Techniques and Related Applications

“…10 Other IC applications incorporate SiN x as a dielectric such as metal-insulator-metal capacitors and thin film transistors (TFTs) due to its high dielectric constant which enables the deposition of thinner films while preserving higher breakdown voltage and lower leakage current. 15,16 In an analogous manner, SiN x and SiC y thin films are successfully incorporated into active optical and optoelectronic devices due to their wide bandgap (2.3 eV for SiC y and 5.1 eV for SiN x ), and elevated electrical breakdown voltage, including panel displays, lighting, and light-emitting devices. 4,[17][18][19] In this respect, both types of Si-based coatings are employed as permeation barriers and encapsulation layers in light-emitting devices (LEDs), and organic LEDs (OLEDs), [20][21][22][23] as well as in the fabrication of various planar optical systems and optical waveguides.…”

“…In this respect, Tables II and III present details of very recent vapor phase deposition techniques of SiN x thin films, along with a synopsis of intended applications. 15,16,[20][21][22][23][24][25][31][32][33][34][36][37][38] More specifically, Table II summarizes PVD and CVD work, while Table III focuses exclusively on atomic layer deposition ALD.…”

Ultrathin, High Capacitance Capping Layers for Silicon Electronics with Conductive Interconnects in Flexible, Long‐Lived Bioimplants

“…[43] Proton transfer from water to this surface oxygen can yield surface-bound hydroxyl species that enhance the reactivity at the interface for the chemisorption of ALD precursors. [44,45] Evaporation of a layer of Ti or Cr, [46] or surface functionalization with self-assembled monolayer (e.g., by the use of OH-terminated alkanethiolate to form Au-S anchor on one end, and -OH groups on the other end for ALD growth) [47][48][49] can further improve the adhesion between the Au and HfO 2 and thus enhance the performance as a barrier material.…”

Building a Better Capacitor with Thin-Film Atomic Layer Deposition Processing

“…Hafnium oxide has been a dielectric that has been receiving a lot of attention from researchers in the silicon device industry. [5] It has a higher k-value than aluminum oxide and silicon oxide, two very common dielectrics that are already used in industry and research while still providing for low leakage currents and high breakdown voltages.…”