Wen-Tse Hsieh

Downscaling limit of equivalent oxide thickness in formation of ultrathin gate dielectric by thermal-enhanced remote plasma nitridation

The gate-oxide downscaling limit in thermal-enhanced remote plasma nitridation (RPN) process for forming ultrathin gate dielectric has been extensively investigated. In this work, the radical-induced re-oxidation effect has been observed as the base-oxide thickness less than 20 /spl Aring/. Nevertheless, for the base-oxide thickness thicker than 17 /spl Aring/, the RPN process still can effectively reduce the equivalent oxide thickness (EOT) and almost no transconductance degradation is observed. Further thinning of the base oxide will degrade the reduction of EOT and the transconductance with the RPN process, due to the penetration of nitrogen radicals into the active region. The physical and electrical properties of the ultrathin oxides (10 /spl sim/ 20 /spl Aring/) affected by this radical penetration have been studied extensively as well. Finally, the thinnest thickness has been estimated by compromising the feasible base-oxide thickness, the degradation of device performance, and the gate leakage criteria. Based on the forementioned criteria, we rind the 14 /spl Aring/ EOT to be the downscaling limit of the gate-oxide thickness.

The effect of remote plasma nitridation on the integrity of the ultrathin gate dielectric films in 0.13 μm CMOS technology and beyond

The authors report the effect of the remote plasma nitridation (RPN) process on characteristics of ultrathin gate dielectric CMOSFETs with the thickness in the range of 18 /spl Aring//spl sim/22 /spl Aring/. In addition, the effect of RPN temperature on the nitrogen-profile within the gate dielectric films has been investigated. Experimental results show that the thinner the gate dielectric films, the more significant effect on reducing the gate current and thinning the thickness of gate dielectric films by the RPN process. Furthermore, the minimum dielectric thickness to block the penetration of B and N has been estimated based on the experimental results. The minimum RPN gate dielectric thickness is about 12 /spl Aring/.

Using porous silicon as semi-insulating substrate for /spl beta/-SiC high temperature optical-sensing devices

This work demonstrates the availability of using porous silicon as semi-insulating substrate for /spl beta/-SiC high temperature optical sensing devices. An MSM structure was fabricated both on a porous silicon substrate and a conventional silicon substrate, respectively. Experimental results show the optical current ratio can be improved up to 400% at room temperature and 3000% at 200/spl deg/C operating temperature, respectively, with the porous silicon substrate.

A high breakdown-voltage SiCN/Si heterojunction diode for high-temperature applications

Cubic crystalline p-SiCN films are deposited on n-Si[100] substrates to form SiCN/Si heterojunction diodes (HJDs) with a rapid thermal chemical vapor deposition (RTCVD) technique. The developed SiCN/Si HJDs exhibit good rectifying properties up to 200/spl deg/C. At room temperature, the reverse breakdown voltage is more than 29 V at the leakage current density of 1.2/spl times/10/sup -4/ A/cm/sup 2/. Even at 200/spl deg/C, the typical breakdown voltage of SiCN/Si HJDs is still preserved about 5 V at the leakage current density of 1.47/spl times/10/sup -4/ A/cm/sup 2/. These properties are better than the /spl beta/-SiC on Si HJDs for high temperature applications.

An a-SiGe:H phototransistor integrated with a Pd film on glass substrate for hydrogen monitoring

A novel a-SiGe:H optoelectronic hydrogen gas sensing device has been developed. The optoelectronic gas sensing device integrated a high optical gain a-SiGe:H optical sensor with a sputtered palladium (Pd) film on a glass substrate. Through the mechanism of the Pd films transmitted optical power modulated with the H/sub 2/ concentration in atmosphere, the device can be operated at room temperature with a wider range (50 ppm to 133000 ppm) and faster response, in comparison to a conventional Pd catalytic type H/sub 2/ sensors, thus providing a good candidate for hydrogen monitoring.

Novel SiC/Si heterostructure negative-differential-resistance diode for use as switch with high on/off current ratio and low power dissipation

A novel p-SiC/n-Si heterostructure negative-differential-resistance (NDR) diode with special current-voltage (I-V) characteristics is reported. Under reverse biases, the I-V curve of this device possesses an N-shaped NDR with a high peak-to-valley current ratio (PVCR) and a broad high-impedance valley region. For use as a switch, it can easily achieve a very low off-state current and a high on/off current ratio, as compared to the conventional N-shaped NDR devices. Hence, performance with a more effective switching action and lower power dissipation can be expected. Furthermore, obvious NDRs can even be obtained at a temperature up to 300/spl deg/C, indicating this device is also potential for high-temperature applications.

SiC/Si heterostructure negative-differential-resistance diode for high-temperature applications

In this letter, we report the observation of N-shaped negative-differential-resistance (NDR) characteristics in a SiC/Si heterostructure diode. The typical NDR in this device has a peak-to-valley current ratio (PVCR) of 44 and a high peak current of 4.8 mA at room temperature. A possible model based on the multi-tunneling process was proposed to explain the origin of the NRD in this device. The most attractive feature of this device is its high-temperature NDR characteristics. An obvious NDR with a PVCR of as high as 9 is obtained at 200 °C, indicating that this SiC/Si heterostructure NDR diode is promising for high-temperature electronic applications.

Cubic Single-Crystalline Si1 − x − y C x N y Films with Mirror Face Prepared by RTCVD

© The Electrochemical Society, Inc. [2001]. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in [Electrochemical and Solid-State Letters, Vol.4, No.11, pp.G91-G93].”

A high optical-gain /spl beta/-SiC bulk-barrier phototransistor for high-temperature applications

A high optical-gain /spl beta/-SiC phototransistor (PT) with a bulk-barrier structure has been fabricated on a silicon substrate. It demonstrated high optical gains of 145 at 25/spl deg/C and 106 at 250/spl deg/C, under a 10-V bias and 10-/spl mu/W incident optical power with a wavelength of 500 nm. The high optical gains at elevated temperatures are attributed to not only the excellent high-temperature properties of SiC materials, but also the bulk-barrier structure, in which the formed potential barrier, the short base region and an effect of thinning the quasi-neutral base region to zero thickness lead to a greatly enhanced current gain. The developed /spl beta/-SiC bulk-barrier PT possesses a potential for high-temperature high-gain optical-sensing applications.

A novel SiC/Si heterojunction diode with high-temperature bi-directional N-shaped negative-differential-resistances for high-temperature applications

Abstract A novel n-SiC/p-Si heterojunction diode with high-temperature bi-directional N-shaped negative-differential-resistances (NRDs) was reported. At room temperature, the device possesses NDRs with peak-to-valley current ratios (PVCRs) of about 21 and 236 at forward and reverse biases, respectively. Under reverse biases, this device achieves an NDR with a PVCR of 40 at 200°C. In addition, it possesses obvious NDRs even up to 300°C. This high-temperature NDR characteristic provides this novel SiC/Si heterojunction diode a potential for high-temperature applications, such as high-temperature solid-state switches.