A new GaAs MMIC process technology using 0.5 mu m gate asymmetric LDD structure GaAs BP-MESFETs combined with high-dielectric-constant thin-film capacitors

Abstract

A fabrication process of 0.5 Gm gate GaAs-MESFETs combined with high-dielectric-constant thin-film capacitors was investigated. A buried p layer (BP) is employed to suppress short-channel effects by using the carbon ion implantation technique. These BP-MESFETs have a self-aligned n+ asymmetric lightly doped drain (LDD) structure to realize low source resistance and high drain breakdown voltage. The planarization technique was adopted to deposit an Au overlayer on top of the 0.5 pm WSi gate to improve the high-frequency performance by reducing the gate resistance. These BP-MESFETs have a high K value, over 230 mA V-2 mm-'. and a maximum freauencv of oscillation fmnr of 60 GHz with an n+ asymmetric structure.We also have developed high-dielectric-constant SrliOa thin-film capacitors by using the low-temperature RF sputtering method. These SrTiOa films have high e,, over 100, and low leakage current density, under 1 x at 1 MV cm-'. By using this SrTiOs capacitor for the bypass capacitors of the MMIC, we can reduce the pin counts of the MMIC and will be able to realbe a shrinkage of the total size of the RF unit of a cellular telephone. We have fabricated the front-end IC of a cellular telephone using this newly developed process technology, and can achieve low power consumption. A transistor) have been developed for these applications.Recently, i n order to improve the poor uniformity, reproducibility, and manufacturability of the conventional 0268-1242/95/111534+07519.50 0 1995 IOP Publishing Ltd GaAs MESFET with a recessed gate structure, selfaligned GaAs MESFETs with a refractoIy metal gate such as WSi, WSN, or WN have been developed for the GaAs ICs (integrated circuits). The development of the self-aligned MESFET (SAFET) process was primarily stimulated for GaAs digital circuits. Therefore, most of the self-aligned GaAs MESFETs with refractory metal gates already reported had a symmetric lightly doped drain (LDD) structure [4]. I n our recent work, self-aligned GaAs MESFETs were applied for analoguefront-end ICs of cellular telephones using the nt asymmetric LDD structure. By adoping this nt asymmetric LDD structure, we can realize high drain breakdown voltage and low source

New BST–silica suspension coating material for dielectric thin films fabricated at low temperatures

“…This behaviour is typical for dielectric thin films. 15 The leakage current in practical applications is required to be ,10 28 A mm 22 at 3 V. 2,15 The leakage current for this stack was y9610 210 A mm 22 at 3 V. This value thus satisfies the requirements for practical applications for this stack.…”

“…Recently, there have been significant efforts to develop metal insulator metal (MIM) capacitors using high dielectric thin films for radio frequency (RF) devices. 1,2 There are two typical processes used to form dielectric thin films: a wet process, such as the metal organic deposition process (MOD) 3 and a dry process, including metal organic chemical vapour deposition (MOCVD) 4 and physical vapour deposition (PVD). 5 Both processes, however, have several shortcomings as described below.…”

“…However, in this technique, an annealing temperature of 750uC was required for sufficient crystallisation. 8 High leakage currents 2 and high voltage coefficients of capacitance 9 are also problems for Ba 0 . 7 Sr 0 .…”

A New Liquid Precursor with Improved Thermal Stability for Chemical Vapor Deposition of Copper

“…Hexafluoracetylacetone (Hhfac) and teovs were purchased from Strem Chemicals. 1H (proton), 13C (carbon- 13), and 19F (fluorine-19) nuclear magnetic resonance (NMR) data were collected on an AMX400 Brucker instrument. Mass spectrometry data were collected on a VG7O7OE mass spectrometer operated in electron impact (El) mode at 70 eV.…”