An advanced PSA technology for high-speed bipolar LSI

An advanced method for polysilicon self-aligned (PSA) bipolar LSI technology has realized a miniaturized transistor for high performance. By introducing the overlapping structure for double polysilicon electrodes, the emitter area is reduced to 1 µm × 3 µm and the base junction is reduced to 0.3 µm. The CML integrated circuit composed of this transistor has achieved a minimum propagation delay time of 0.29 ns/gate with power dissipation of 1.48 mW/gate. Compared to the conventional PSA method, this technology promises to fabricate higher speed and higher density LSI's.     

A 22-nm damascene-gate MOSFET fabrication with 0.9-nm EOT and local channel implantation

We introduce a novel CMOS transistor fabrication technique using damascene gate with local channel implantation (LCI). This transistor has a benefit to reduce the resistance of source/drain extension (SDE) localizing the severe blanket channel implantation under the channel only. It can reduce the junction capacitance as well. This process technology is reliable for the formation of channel length down to 22 nm with smooth gate line edge roughness. Some unique processes for the small transistor fabrication are also introduced. The 22-nm nMOSFET with 0.9 nm RTO is achieved with the drive current of 930 /spl mu/A//spl mu/m for the off-current of 100 nA//spl mu/m at 1.0 V. Hot carrier reliability exceeding 10 years for 1.0 V operation is also obtained.     

A new polysilicon process for a bipolar device-PSA technology

A new polysilicon process has been developed to obtain high packing density, high speed, and low-power LSIs. The new process, called the polysilicon self-aligned (PSA) method is based on a new fabrication concept for dimensional reduction and does not require fine patterning and accurate mask alignment. For an application example of this new method, an ECL gate with 0.6 ns delay time, 0.5 pJ power-delay product, and 6400 /spl mu/m/SUP 2/ gate area has been achieved. Furthermore, by introducing a polysilicon diode (PSD) and Schottky barrier diode (SBD) to the PSA method, a low-power Schottky-diode-transistor-logic (SDTL) gate with 1.6 ns delay time, 0.8 pJ power-delay product, and 2000 /spl mu/m/SUP 2/ gate area has been successfully developed.     

220-GHz metamorphic HEMT amplifier MMICs for high-resolution imaging applications

In this paper, the development of 220-GHz low-noise amplifier (LNA) MMICs for use in high-resolution active and passive millimeter-wave imaging systems is presented. The amplifier circuits have been realized using a well-proven 0.1-/spl mu/m gate length and an advanced 0.05-/spl mu/m gate length InAlAs/InGaAs based depletion-type metamorphic high electron mobility transistor technology. Furthermore, coplanar circuit topology in combination with cascode transistors was applied, leading to a compact chip size and an excellent gain performance at high millimeter-wave frequencies. A realized single-stage 0.05-/spl mu/m cascode LNA exhibited a small-signal gain of 10 dB at 222 GHz, while a 0.1-/spl mu/m four-stage amplifier circuit achieved a linear gain of 20 dB at the frequency of operation and more than 10 dB over the bandwidth from 180 to 225 GHz.     

A technique to improve the drive current of high-voltage I/O transistors in digital CMOS technologies

By combining a 0.12-/spl mu/m-long 1.2-V thin-oxide transistor with a 0.22-/spl mu/m-long 3.3-V thick-oxide transistor in a 0.13-/spl mu/m CMOS process, a composite MOS transistor structure with a drawn gate length of 0.34 /spl mu/m is realized. Measurements show that at V/sub GS/=1.2 V and V/sub DS/=3.3 V, the composite transistor has more than two times the drain current of the minimum channel length (0.34 /spl mu/m) 3.3-V thick-oxide transistor, while having the same breakdown voltage (V/sub BK/) as the thick-oxide transistor. Exploiting these, it should be possible to implement 3.3-V I/O transistors with better combination of drive current, threshold voltage (V/sub T/) and breakdown voltage in conventional CMOS technologies without adding any process modifications.     

A configurable ROM circuit for use in gate arrays

A double word-line memory ROM (DWM-ROM) for use in gate arrays is described. It allows for an automatic layout by reducing the input pin count in the word lines by using two-step addressing. The advantage of this method has been verified by implementing a 16-bit microprocessor using an 8 K-gate array, based on a gate-isolated cell configuration, employing 1.5-/spl mu/m double-metal CMOS technology. The 16-bit /spl times/ 64-word ROM in the processor saves 30% of the transistor area due to the DWM-ROM.     

A 4 /spl mu/m NMOS NAND structure PLA

A PLA of NAND structure, using a NMOS Si gate process, has been developed to minimize chip area and maintain medium fast speed. The smallest memory cell size of 7/spl times/9 /spl mu/m is achieved by using ion implantation for PLA bit programming with 4 /spl mu/m design rules. Dynamic clocking scheme and self-timing circuits which are used in this PLA are described. With PLA size at 20/spl times/20/spl times/20, transistor size of 8 /spl mu/m/4 /spl mu/m, and cell size of 7/spl times/12 /spl mu/m, an internal access time of 150 ns is achieved with an external 4 MHz clock. Measured circuit power dissipation is 20 mW under normal conditions.     

A high-speed P-channel random access 1024-bit memory made with electron lithography

A switched capacitor, p-channel, 1024 bit random access memory has been made with electron lithography. The basic circuit was the same as that described by Boll and Lynch (see abstr. B35355 or C22818 fo 1973) but with halved lateral dimensions. The gate length of the switching transistor was 4 /spl mu/m, and the chip size was 1.2/spl times/1.8 mm. In order to fabricate the device, a 1 /spl mu/m alignment accuracy was required. Even with this modest shrinking of feature size, the minimum access time of the memory was reduced from 100 ns to less than 50 ns.     

A low-power highly linear cascoded multiple-gated transistor CMOS RF amplifier with 10 dB IP3 improvement

A low-power highly linear CMOS RF amplifier circuit composed of a Multiple-Gated common-source FET TRansistor (MGTR) in cascode configuration is reported. In a MGTR amplifier, linearity is improved by using transconductance linearization which can be achieved by canceling the negative peak value of g/sub m/" of the main transistor with the positive one in the auxiliary transistor having a different size and gate drive combined in parallel. This enhancement, however, is limited by the distortion originated from the combined influence of g/sub m/' and harmonic feedback, which can greatly be reduced by the cascoding MGTR output. IP3 improvement as large as 10 dB has been obtained from an experimental RF amplifier designed at 900 MHz and fabricated using 0.35 /spl mu/m BiCMOS technology using only CMOS at a similar power consumption and gain as those obtainable from conventional cascode single gate transistor amplifiers.     

A high speed molybdenum gate MOS RAM

Describes a high speed 16K molybdenum gate (Mo-gate) dynamic MOS RAM using a single transistor cell. New circuit technologies, including a capacitive-coupled sense-refresh amplifier and a dummy sense circuit, enable the achievement of high speed performance in combination with reduced propagation delay in the molybdenum word line due to the low resistivity. The n-channel Mo-gate process was established by developing an evaporation apparatus and by an improved heat treatment to reduce surface charge density. Ultraviolet photolithography for 2 /spl mu/m patterns and HCl oxidation for 400 /spl Aring/ thick gate oxide are used. The 16K word/spl times/1 bit device is fabricated on a 3.2 mm/spl times/4.0 mm chip. Cell size is 16 /spl mu/m/spl times/16 /spl mu/m Access time is less than 65 ns at V/SUB DD/=7 V and V/SUB BB/=-2 V. Power dissipation is 210 mW at 170 ns read-modify-write (RMW) cycle.     

A low-power highly linear cascoded multiple-gated transistor CMOS RF amplifier with 10 dB IP3 improvement (Revised)

A low-power highly linear CMOS RF amplifier circuit composed of a Multiple-Gated common-source FET TRansistor (MGTR) in cascode configuration is reported. In an MGTR amplifier, linearity is improved by using transconductance linearization which can be achieved by canceling the negative peak value of g/sub m/" of the main transistor with the positive one in the auxiliary transistor having a different size and gate drive combined in parallel. This enhancement, however, is limited by the distortion originated from the combined influence of g/sub m/' and harmonic feedback, which can greatly be reduced by the cascoding MGTR output. IP3 improvement as large as 10 dB has been obtained from an experimental RF amplifier designed at 900 MHz and fabricated using 0.35 /spl mu/m BiCMOS technology using only CMOS at a similar power consumption and gain as those obtainable from conventional cascode single gate transistor amplifiers.     

A new method to extract EOT of ultrathin gate dielectric with high leakage current

The standard capacitance-voltage (C-V ) technique can no longer determine accurately the equivalent oxide thickness (EOT) for an advanced CMOS transistor with ultrathin gate dielectric where there is high gate leakage current, as well as series resistance; this situation will get worse as the CMOS transistor's scaling trend continues. This paper describes a simple methodology based on dual-frequency C-V measurement and four-element circuit model to extract accurately the EOT in the presence of gate leakage current and series resistance. This method can be effective with a current density of 1000 A/cm/sup 2/ for a 10 /spl mu/m /spl times/10 /spl mu/m capacitor. Such a high current density will satisfy the projected gate leakage current requirements for many generations of CMOS technologies, as specified in the 2003 International Technology Roadmap for Semiconductors.     

Schottky collector I/SUP 2/L

A new I/SUP 2/L gate which promises increased packing density and increased speed is discussed. It incorporates the use of a Schottky contact as the collector of the vertical switching transistor of an I/SUP 2/L gate. Calculations and experiments show that the problems associated with this structure (low downward beta) can be controlled by limiting both the fan-out and the fan-in. Delays of less than 10 ns have been measured using a 10-/spl mu/m technology and a 6-/spl mu/m-thick epi. A divide-by-two circuit with a maximum toggle frequency of 12.5 MHz has been built. The additional fan-in limitation of the logic is described.     

A 12-18 GHz medium-power GaAs MESFET amplifier

Two medium-power 12-18 GHz GaAs FET amplifiers, one single-ended and one balanced, have been developed. A minimum output power across the Ku-band of 200 mW with an associated gain of 4.0 dB was achieved with the balanced module. The transistor used in this study has gate dimensions of 300/spl times/1/spl mu/m. The technology, RF performance, and characterization of the transistor are discussed in detail, as are the design and performance of both single-ended and balanced amplifier modules.     

Single transistor MOS RAM using a short-channel MOS transistor

The relationship between sensitivity and other factors in the sense circuit of a single transistor MOS RAM has been investigated by computer simulation. An expression for sensitivity of the sense circuit has been derived. It suggests key points to increase the sensitivity of the sense circuit. A new sense circuit that defects a signal less than /spl plusmn/30 mV and has low power capability 50 /spl mu/W/circuit is realized by following the suggestions. The high performance of the proposed sense circuit has been verified through the fabrication of a 1K MOS RAM. Fine pattern technology, such as 2-/spl mu/m minimum pattern width and spacing and 500-/spl Aring/ gate oxide thickness, has been adopted. The threshold voltage of the MOS transistor is 0.8 V and dc supplies are 7 V and /spl plusmn/2 V. This 1K RAM has characteristics of 80-ns access time, 150-ns cycle time, and 30-mW power dissipation.     

A fault-tolerant 256K RAM fabricated with molybdenum-polysilicon technology

Describes a 256K molybdenum-polysilicon (Mo-poly) gate dynamic MOS RAM using a single transistor cell. Circuit technologies, including a capacitive-coupled sense-refresh amplifier and a redundant circuitry, enable the achievement of high performance in combination with Mo-poly technology. Electron-beam direct writing and dry etching technologies are fully utilized to make 1 /spl mu/m accurate patterns. The 256K word/spl times/1 bit device is fabricated on a 5.83 mm/spl times/5.90 mm chip. Cell size is 8.05 /spl mu/m/spl times/8.60 /spl mu/m. The additional 4K spare cells and the associated circuits, in which newly developed electrically programmable elements are used, occupy less than 10 percent of the whole chip area. The measured access time is 160 ns under V/SUB DD/=5 V condition.     

A high-speed 64K CMOS RAM with bipolar sense amplifiers

A TTL-compatible 64K static RAM with CMOS-bipolar circuitry has been developed using a 1.2-/spl mu/m MoSi gate n-well CMOS-bipolar technology. Address access time is typically 28 ns, with 225 mW active power and 100 nW standby power. A CMOS six-transistor memory cell is used. The cell size is 18/spl times/20 /spl mu/m, and the chip size is 5.95/spl times/6.84 mm. The n-p-n transistors are used in the sense amplifiers, voltage regulators, and level clamping circuits. The bipolar sense amplifiers reduce the detectable bit line swing, thus improving the worst-case bit line delay time and the sensing delay time. In order to reduce the word line delay, the MoSi layer, which has 5 /spl Omega//sheet resistivity, was used for the gate material. The n-well CMOS process is based on a scaled CMOS process, and collector-isolated n-p-n transistors and CMOS are integrated simultaneously without adding any extra process steps and without causing any degradation of CMOS characteristics. The n-p-n transistor has a 2-GHz cutoff frequency at 1 mA collector current.     

An 18 ns CMOS/SOS 4K static RAM

A high-speed CMOS/SOS 4K word/spl times/1 bit static RAM is described. The RAM features a MoSi/SUB 2/ gate CMOS/SOS technology with 2 /spl mu/m gate length and 500 /spl Aring/ thick gate oxide. Performance advantage of SOS over bulk is discussed for the scaled-down MOS LSI with 1-2 /spl mu/m gate. A standard 6-transistor CMOS cell and a two-stage sense amplifier scheme are utilized. In spite of the rather conservative 3.5 /spl mu/m design rule except for the 2 /spl mu/m gate length, the cell size of 36/spl times/36 /spl mu/m, the die size of 3.11/spl times/4.07 mm, and the typical read access and cycle time of 18 ns are achieved. The active and standby power dissipation are 200 mW and 50 /spl mu/W, respectively.     

Characterization of 1.9- and 1.4-nm ultrathin gate oxynitride by oxidation of nitrogen-implanted silicon substrate

For gate oxide thinned down to 1.9 and 1.4 nm, conventional methods of incorporating nitrogen (N) in the gate oxide might become insufficient in stopping boron penetration and obtaining lower tunneling leakage. In this paper, oxynitride gate dielectric grown by oxidation of N-implanted silicon substrate has been studied. The characteristics of ultrathin gate oxynitride with equivalent oxide thickness (EOT) of 1.9 and 1.4 nm grown by this method were analyzed with MOS capacitors under the accumulation conditions and compared with pure gate oxide and gate oxide nitrided by N/sub 2/O annealing. EOT of 1.9- and 1.4-nm oxynitride gate dielectrics grown by this method have strong boron penetration resistance, and reduce gate tunneling leakage current remarkably. High-performance 36-nm gate length CMOS devices and CMOS 32 frequency dividers embedded with 57-stage/201-stage CMOS ring oscillator, respectively, have been fabricated successfully, where the EOT of gate oxynitride grown by this method is 1.4 nm. At power supply voltage V/sub DD/ of 1.5 V drive current Ion of 802 /spl mu/A//spl mu/m for NMOS and -487 /spl mu/A//spl mu/m for PMOS are achieved at off-state leakage I/sub off/ of 3.5 nA//spl mu/m for NMOS and -3.0 nA//spl mu/m for PMOS.     

High performance 35 nm gate length CMOS with NO oxynitride gate dielectric and Ni salicide

The 35 nm gate length CMOS devices with oxynitride gate dielectric and Ni salicide have been fabricated to study the feasibility of higher performance operation. Nitrogen concentration in gate oxynitride was optimized to reduce gate current I/sub g/ and to prevent boron penetration in the pFET. The thermal budget in the middle of the line (MOL) process was reduced enough to realize shallower junction depth in the S/D extension regions and to suppress gate poly-Si depletion. Finally, the current drives of 676 /spl mu/A//spl mu/m in nFET and 272 /spl mu/A//spl mu/m in pFET at V/sub dd/=0.85 V (at I/sub off/=100 nA//spl mu/m) were achieved and they are the best values for 35 nm gate length CMOS reported to date.