Steve Cho - Academia.edu (original) (raw)

Papers by Steve Cho

Research paper thumbnail of An On-Chip Hermetic Packaging Technology for Micromechanical Devices

1998 Solid-State, Actuators, and Microsystems Workshop Technical Digest, 1998

A novel on-chip hermetic packaging technology utilizing electrostatic bonding and eutectic sealin... more A novel on-chip hermetic packaging technology utilizing electrostatic bonding and eutectic sealing is presented. Planarization of the lead transfers is not required since the leads conform to the interfacial layer by forming a eutectic seal with the bonding layer (amorphous polysilicon). The leads also have an isolation resistance of >4Gillsq. This approach requires only one masking step and exhibits low induced stress, high thermal shock resistance, and a leak rate of <10. 16 SCCM.

Research paper thumbnail of United States Patent ( 19 ) Wise et al . 54 SELF-TESTING CAPACITIVE PRESSURE TRANSDUCER AND METHOD

2,919,578 1/1960 Sink .................................. 73/861.44 3,407,658 10/1968 Kerbow et al... more 2,919,578 1/1960 Sink .................................. 73/861.44 3,407,658 10/1968 Kerbow et al. .................. 73/861.44 3,593,576 7/1971 Greer ............................... 73/861.44 3,882,723 5/1975 Wickham .......... ... 73/861.47 4,413,530 11/1983 Guadagnin et al. .. ... 73/861.47 4,479,070 10/1984 Frische et al. ........ ... 73/861.47 4484,479 11/1984 Eckhardt........... ... 73/861.47 4,526,041 7/1985 Beller et al. ........... ... 73/861.47 4,754,651 7/1988 Shortridge et al. .................. 73/4. R. 4,825,747 5/1989 Bardin et al. .................... 73/861.47 5,082,242 1/1992 Bonne et al. ................... 251/129.01 5,149,673 9/1992 MacDonald et al. ............... 437/192

Research paper thumbnail of The Key Attributes that Drive University Entrepreneurship

TEMSCON 2020, 2020

In this new age of connectivity, information and artificial intelligence, start-ups have played a... more In this new age of connectivity, information and artificial intelligence, start-ups have played a key role in its growth. In particular, universities have played a pivotal role in the rise of innovative enterprises and is a core component of the entrepreneurial ecosystem. Understanding key drivers of university-based entrepreneurship could assist academic institutions in focusing their resource investment and better prepare students to pursue projects beyond the classroom. This paper explores various factors in university-based start-up creation, their impact on the ever-growing ecosystem, and derives an understanding of the key attributes' relationships. The attributes analyzed in this paper are the universities' academic strength, financial resources, and regional support. The increasing trend of innovation and entrepreneurship is spreading throughout campuses globally, resulting in educational institutions seeking guidance to develop more student-based ventures. T-tests were performed to determine the relationship of the data, regression to characterize the relationship, Coefficient of Determination to understand the quality of correlation, and Regression Coefficients to measure the sensitivity of the relationship. This paper explores what the entrepreneurial universities have in common; they're able to build the content of their startup's product (engineering strength) while having the ability to support their business around the product (business strength).

Research paper thumbnail of A high-performance microflowmeter with built-in self test

Sensors and Actuators A: Physical, 1993

Research paper thumbnail of Internal stress compensation and scaling in ultrasensitive silicon pressure sensors

IEEE Transactions on Electron Devices, Jan 1, 1992

The pressure sensitivity of boron-doped silicon membranes has been characterized as a function of... more The pressure sensitivity of boron-doped silicon membranes has been characterized as a function of diaphragm dimensions and internal membrane stress. Using an electrostatic technique based on silicon microbridges, the internal stress for p++ silicon (on glass), LPCVD silicon dioxide, and LPCVD silicon nitride was measured; typical values are 40, -300, and 950 MPa, respectively. Silicon membranes with several different edge lengths and deposited oxide and/or nitride coatings were characterized for sensitivity. While the pressure sensitivity can be reduced by more than a factor of twenty in the membranes due to boron-induced internal stress, the use of stress-compensating dielectrics can improve this sensitivity by a factor of six or more. Based on this theory and the measured material parameters, scaled experimental devices show typical sensitivities within 10-20% of the theoretical design targets. Pressure sensitivities as high as 2900 ppm/Pa have been achieved

Research paper thumbnail of An ultrasensitive silicon pressure-based microflow sensor

IEEE Transactions on Electron Devices, Jan 1, 1992

An ultrasensitive silicon pressure-based flowmeter has been developed for use in measuring sub-SC... more An ultrasensitive silicon pressure-based flowmeter has been developed for use in measuring sub-SCCM gas flows in semiconductor process equipment. The device utilizes a capacitive pressure sensor to measure the pressure drop induced by flow across a micromachined silicon flow channel. The flowmeter is fabricated using a single-sided dissolved-wafer process and requires only six masks. The capacitive pressure sensor uses a thin (2.9 pm) stress-compensated membrane, which enables the sensor to monitor differential pressures as low as 1 mtorr while withstanding overpressures greater than 700 torr. Creep and fatigue change the offset by <0.2% full scale and alter the pressure sensitivity by < 0.03 fF/mtorr; the hysteresis observed on all devices has also been < 0.2% full scale, where "full-scale" is defined to be the pressure required to deflect the membrane half the gap distance. The results reported here indicate that it may be possible to extend the pressure range of these devices by an order of magnitude beyond full scale, which would increase the flow resolution from 12 to 16 b and cover a flow range of lo-* to SCCM.

Research paper thumbnail of An On-Chip Hermetic Packaging Technology for Micromechanical Devices

1998 Solid-State, Actuators, and Microsystems Workshop Technical Digest, 1998

A novel on-chip hermetic packaging technology utilizing electrostatic bonding and eutectic sealin... more A novel on-chip hermetic packaging technology utilizing electrostatic bonding and eutectic sealing is presented. Planarization of the lead transfers is not required since the leads conform to the interfacial layer by forming a eutectic seal with the bonding layer (amorphous polysilicon). The leads also have an isolation resistance of >4Gillsq. This approach requires only one masking step and exhibits low induced stress, high thermal shock resistance, and a leak rate of <10. 16 SCCM.

Research paper thumbnail of United States Patent ( 19 ) Wise et al . 54 SELF-TESTING CAPACITIVE PRESSURE TRANSDUCER AND METHOD

2,919,578 1/1960 Sink .................................. 73/861.44 3,407,658 10/1968 Kerbow et al... more 2,919,578 1/1960 Sink .................................. 73/861.44 3,407,658 10/1968 Kerbow et al. .................. 73/861.44 3,593,576 7/1971 Greer ............................... 73/861.44 3,882,723 5/1975 Wickham .......... ... 73/861.47 4,413,530 11/1983 Guadagnin et al. .. ... 73/861.47 4,479,070 10/1984 Frische et al. ........ ... 73/861.47 4484,479 11/1984 Eckhardt........... ... 73/861.47 4,526,041 7/1985 Beller et al. ........... ... 73/861.47 4,754,651 7/1988 Shortridge et al. .................. 73/4. R. 4,825,747 5/1989 Bardin et al. .................... 73/861.47 5,082,242 1/1992 Bonne et al. ................... 251/129.01 5,149,673 9/1992 MacDonald et al. ............... 437/192

Research paper thumbnail of The Key Attributes that Drive University Entrepreneurship

TEMSCON 2020, 2020

In this new age of connectivity, information and artificial intelligence, start-ups have played a... more In this new age of connectivity, information and artificial intelligence, start-ups have played a key role in its growth. In particular, universities have played a pivotal role in the rise of innovative enterprises and is a core component of the entrepreneurial ecosystem. Understanding key drivers of university-based entrepreneurship could assist academic institutions in focusing their resource investment and better prepare students to pursue projects beyond the classroom. This paper explores various factors in university-based start-up creation, their impact on the ever-growing ecosystem, and derives an understanding of the key attributes' relationships. The attributes analyzed in this paper are the universities' academic strength, financial resources, and regional support. The increasing trend of innovation and entrepreneurship is spreading throughout campuses globally, resulting in educational institutions seeking guidance to develop more student-based ventures. T-tests were performed to determine the relationship of the data, regression to characterize the relationship, Coefficient of Determination to understand the quality of correlation, and Regression Coefficients to measure the sensitivity of the relationship. This paper explores what the entrepreneurial universities have in common; they're able to build the content of their startup's product (engineering strength) while having the ability to support their business around the product (business strength).

Research paper thumbnail of A high-performance microflowmeter with built-in self test

Sensors and Actuators A: Physical, 1993

Research paper thumbnail of Internal stress compensation and scaling in ultrasensitive silicon pressure sensors

IEEE Transactions on Electron Devices, Jan 1, 1992

The pressure sensitivity of boron-doped silicon membranes has been characterized as a function of... more The pressure sensitivity of boron-doped silicon membranes has been characterized as a function of diaphragm dimensions and internal membrane stress. Using an electrostatic technique based on silicon microbridges, the internal stress for p++ silicon (on glass), LPCVD silicon dioxide, and LPCVD silicon nitride was measured; typical values are 40, -300, and 950 MPa, respectively. Silicon membranes with several different edge lengths and deposited oxide and/or nitride coatings were characterized for sensitivity. While the pressure sensitivity can be reduced by more than a factor of twenty in the membranes due to boron-induced internal stress, the use of stress-compensating dielectrics can improve this sensitivity by a factor of six or more. Based on this theory and the measured material parameters, scaled experimental devices show typical sensitivities within 10-20% of the theoretical design targets. Pressure sensitivities as high as 2900 ppm/Pa have been achieved

Research paper thumbnail of An ultrasensitive silicon pressure-based microflow sensor

IEEE Transactions on Electron Devices, Jan 1, 1992

An ultrasensitive silicon pressure-based flowmeter has been developed for use in measuring sub-SC... more An ultrasensitive silicon pressure-based flowmeter has been developed for use in measuring sub-SCCM gas flows in semiconductor process equipment. The device utilizes a capacitive pressure sensor to measure the pressure drop induced by flow across a micromachined silicon flow channel. The flowmeter is fabricated using a single-sided dissolved-wafer process and requires only six masks. The capacitive pressure sensor uses a thin (2.9 pm) stress-compensated membrane, which enables the sensor to monitor differential pressures as low as 1 mtorr while withstanding overpressures greater than 700 torr. Creep and fatigue change the offset by <0.2% full scale and alter the pressure sensitivity by < 0.03 fF/mtorr; the hysteresis observed on all devices has also been < 0.2% full scale, where "full-scale" is defined to be the pressure required to deflect the membrane half the gap distance. The results reported here indicate that it may be possible to extend the pressure range of these devices by an order of magnitude beyond full scale, which would increase the flow resolution from 12 to 16 b and cover a flow range of lo-* to SCCM.