Browsing by Author "Lai, JM"

Now showing 1 - 9 of 9

Low noise RF MOSFETs on flexible plastic substrates
(2005-07-01)
Kao, HL
;
Chin, A
;
Hung, BF
;
Lee, CF
;
Lai, JM
We report a low minimum noise figure (NFmin) of 1.1 dB and high associated gain (12 dB at 10 GHz) for 16 gate-finger 0.18-mu m RF MOSFETs, after thinning down the Si substrate to 30 mu m and mounting it on plastic. The device performance was improved by flexing the substrate to create stress, which produced a 25% enhancement of the saturation drain current and lowered NFmin to 0.92 dB at 10 GHz. These excellent results for mechanically strained RF MOSFETs on plastic compare well with 0.13-mu m node (L-g = 80 nm) devices.
Modeling and analysis of nonlinear guideway for double-ball bar (DBB) measurement and diagnosis
(1997-05-01)
Lai, JM
;
Liao, JS
;
Chieng, WH
;
機械工程學系
;
Department of Mechanical Engineering
The purpose of this paper is to study nonlinear geometric errors in multi-axis machine tools. A general mathematical model for guideway systems that can be applied to high-precision machine tools such as CNC lathes is introduced. Using this model, most nonlinear error sources in the guideway systems can be diagnosed by measuring the contouring error using a double-ball bar (DBB). Diagnostic software has been developed to identify system parameters based on the least-squares estimation method. Inputting two or three contouring errors pattern data into this software enables parameters to be identified quickly, based on the nonlinear model. (C) 1997 Published by Elsevier Science Ltd.
Modeling RF MOSFETs after electrical stress using low-noise microstrip line layout
(2005)
Kao, HL
;
Chin, A
;
Lai, JM
;
Lee, CF
;
Chiang, KC
A novel microstrip line layout is developed to direct measure the min. noise figure (NFmin) accurately instead of the complicated de-embedding procedure in conventional CPW line. Very low NFmin of 1.05 dB at 10 GHz is directly measured in 16 gate fingers 0.18 mu m MOSFETs without any de-embedding. Based on the accurate NFmin measurement, we have developed the self-consistent DC, S-parameters and NFmin model to predict device characteristics after the continuous stress with good accuracy.
Precision alignment of mask etching with respect to crystal orientation
(1998-12-01)
Lai, JM
;
Chieng, WH
;
Huang, YC
;
機械工程學系
;
電子工程學系及電子研究所
For most micro-mechanical devices, a high precision alignment of mask pattern to crystal orientation is preferred. Such alignment even becomes critical for devices that simultaneously require a smooth sidewall and minimal undercut. In this article, we present an innovative pre-etching pattern to determine the [110] crystal orientation on [100] silicon wafers. This pattern etched on the wafer allows us to determine the crystal orientation within an accuracy of 0.01 degrees. Such a pre-etching pattern can be used as a valuable reference for all subsequent mask patterns.
Strain-induced very low noise RF MOSFETs on flexible plastic substrate
(2005)
Kao, HL
;
Chin, A
;
Hung, BF
;
Lai, JM
;
Lee, CF
Using microstrip line design to screen substrate resistance generated RF noise, very low 1.1 dB min. noise figure (NFmin) and high 12 dB associate gain are measured at 10 GHz of 0.18 mu m MOSFET on plastic without de-embedding. The die on plastic was thinned to 30 mu m that allows applying uniaxial strain to further lower the 10 GHz NFmin to only 0.92 dB and comparable well with the 0.13 mu m and 90nm nodes MOSFETs.
Structural design and analysis of micromachined ring-type vibrating sensor of both yaw rate and linear acceleration
(2005-01-14)
Weng, JH
;
Chieng, WH
;
Lai, JM
;
機械工程學系
;
Department of Mechanical Engineering
This work presents the design and analysis of a micromachined ring-type motion sensor which can sense both the yaw rate and linear acceleration of a device in that it is installed. It integrates the functions of a gyroscope and an accelerometer. The design of the microstructure is based on the structure of a vibrating ring gyroscope. The analysis, considering the symmetry of the structure, implies that the rotational symmetry and mirror symmetry of the microstructure markedly affect the performance of the sensor. The modes of vibration determined using finite element analysis and the theoretical calculation of the resonant frequency of the structure are presented. The sensitivities of the characteristic of the sensor to the design specification, the fabrication errors and the theoretical errors are discussed. The structure is fabricated based on deep silicon etching and wafer bonding techniques. The process is developed for eliminating the aspect ratio dependent effect (ARDE) in dry etching process. (C) 2004 Elsevier B.V. All rights reserved.
Structural fabrication of a ring-type motion sensor
(2004-05-01)
Weng, JH
;
Chieng, WH
;
Lai, JM
;
機械工程學系
;
Department of Mechanical Engineering
The structural fabrication of a ring-type motion sensor is described. This micromachined ring-type sensor can be used to detect both yaw rate and linear acceleration. The fabrication is based on deep silicon etching and wafer bonding. An aspect ratio dependent effect (ARDE) always occurs in the dry etching process for a micro electromechanical systems (MEMS) device. Additionally, three processes are developed and modified progressively for eliminating ARDE from the fabrication results. Results indicate that the proposed process provides more flexibility than other processes with respect to the structural fabrication of a MEMS device. The sensitivity of the sensor characteristic to the manufacturing errors is considered as well.
The leakage current effect of thin gate oxides (2.4-2.7 nm) with in situ native oxide desorption
(1999-06-01)
Lai, JM
;
Chieng, WH
;
Lin, BC
;
Chin, A
;
Tsai, C
An intrinsic defect may exist in thin gate oxides. Such a defect can increase the leakage current in a manner similar to stress-induced leakage current. In this paper, we have shown that the effect of this intrinsic defect can be greatly reduced by in situ removal of the native oxide followed by growing a high-quality thermal oxide. By using such in situ cleaning, ultrathin oxides can be prepared with atomically smooth interfaces, good thickness uniformity, and reduced leakage currents. (C) 1999 The Electrochemical Society. All rights reserved.
Very low noise RIF nMOSFETs on plastic by substrate thinning and wafer transfer
(2005-11-01)
Kao, HL
;
Hung, BF
;
Chin, A
;
Lai, JM
;
Lee, CF
A very low minimum noise figure (NFmin) of 1.2 dB and a high associated gain of 12.8 dB at 10 GHz were measured for six-finger, 0.18-mu m radio frequency (RF) metal-oxide semiconductor field-effect transistors mounted on insulating plastic following substrate-thinning (similar to 30 mu m) and wafer transfer. Before this process, the devices had a slightly better RF performance of 1.1-dB NFmin anda 13.7-dB associated gain. The small RF performance degradation of the active transistors transferred to plastic shows the potential of integrating electronics onto plastic.