TaN BOTTOM ELECTRODE THERMAL SENSING RESISTOR FOR MEMs-BASED BOLOMETER APPLICATION

In this work, TaN bottom electrode thermal sensing resistor for MEMs-based bolometer was designed and fabricated by 200 mm Cu -BEOL compatible process. Thermal sensing material was B -doped alpha- Si deposited by PECVD in situ doping process. PVD TaN film was used as the bottom electrode. Dedicated process on modified tool was introduced to achieve a good contact between the TaN and the sensing material. There are both CVD and Etch chambers installed on this modified tool. Wafer with bottom electrode pattern was pre-cleaned firstly by low-power Ar /CF4 gas to remove oxide and possible surface residue on TaN in the etch chamber. Then, the wafer was transferred to CVD chamber through transfer chamber in vacuum condition. With vacuum transfer condition under tight Q-time control, Ohmic contact can be achieved for the TaN bottom electrode and B -doped alpha- Si . Through the IV curve and TCR data, it can be seen that the bottom electrode device can well meet the MEMs-based bolometer requirements.

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Comparative Study of Top Electrode and Bottom Electrode Sensing Resistor Schemes for MEMs Based Bolometer Application

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.705.275 ◽

2013 ◽

Vol 705 ◽

pp. 275-280

Author(s):

Jin Feng Feng ◽

Xiao Xu Kang ◽

Chao Yuan ◽

Qing Yun Zuo ◽

Shou Mian Chen ◽

...

Keyword(s):

Bottom Electrode ◽

Dielectric Material ◽

Bridge Structure ◽

Material Loss ◽

Electrode Layer ◽

Well Control ◽

Sensing Material ◽

Product Application ◽

Important Structure

In this work, CMOS compatible MEMs based bolometer process was developed on 200mm std CMOS Cu BEOL. As to the micro-bridge structure, TaN was used as electrode material, and alpha-Si film was used as the sacrificial material fabricated by low Temperature PECVD technology. No metal or dielectric material plug was used for the anchor supporting structure, which make the process much more controllable and flexible. For one of the Sensor product application, B-doped alpha-Si film was used as sensing material fabricated by PECVD and in situ doping process. The sensing resistor, which is the most important structure of this product, was fabricated with different approaches. In the top electrode scheme, TaN was used as electrode layer on top of sensing material whose pattern was to define the sensing resistor. In the bottom electrode scheme, TaN electrode layer was located on bottom of sensing material. The two schemes were comparatively studied to show their advantages and drawbacks. Conclusion was made that both the scheme can match the product requirements, and bottom electrode scheme was the better choice for its well control for sensing material loss and uniformity of sensing resistor, which was most important to the performance and yield of MEMs based IR sensor products.

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Microstructural Characterization of Au-Ge-Ni based ohmic contacts to GaAs/AlGaAs modfet device

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126433 ◽

1987 ◽

Vol 45 ◽

pp. 326-327

Author(s):

A.K. Rai ◽

A.K. Petford-Long ◽

A. Ezis ◽

D.W. Langer

Keyword(s):

Contact Resistance ◽

Ohmic Contact ◽

Ohmic Contacts ◽

Microstructural Characterization ◽

Almost Everywhere ◽

Spacer Layer ◽

Good Contact ◽

The Relationship ◽

Lower Contact

Considerable amount of work has been done in studying the relationship between the contact resistance and the microstructure of the Au-Ge-Ni based ohmic contacts to n-GaAs. It has been found that the lower contact resistivity is due to the presence of Ge rich and Au free regions (good contact area) in contact with GaAs. Thus in order to obtain an ohmic contact with lower contact resistance one should obtain a uniformly alloyed region of good contact areas almost everywhere. This can possibly be accomplished by utilizing various alloying schemes. In this work microstructural characterization, employing TEM techniques, of the sequentially deposited Au-Ge-Ni based ohmic contact to the MODFET device is presented.The substrate used in the present work consists of 1 μm thick buffer layer of GaAs grown on a semi-insulating GaAs substrate followed by a 25 Å spacer layer of undoped AlGaAs.

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Optimization of a Low-Power Chemoresistive Gas Sensor: Predictive Thermal Modelling and Mechanical Failure Analysis

Sensors ◽

10.3390/s21030783 ◽

2021 ◽

Vol 21 (3) ◽

pp. 783 ◽

Cited By ~ 1

Author(s):

Andrea Gaiardo ◽

David Novel ◽

Elia Scattolo ◽

Michele Crivellari ◽

Antonino Picciotto ◽

...

Keyword(s):

Low Power ◽

Failure Analysis ◽

Gas Sensors ◽

High Performance ◽

Gas Sensing ◽

Mechanical Failure ◽

Sensing Applications ◽

Theoretical Approaches ◽

Sensing Material ◽

Silicon Bulk

The substrate plays a key role in chemoresistive gas sensors. It acts as mechanical support for the sensing material, hosts the heating element and, also, aids the sensing material in signal transduction. In recent years, a significant improvement in the substrate production process has been achieved, thanks to the advances in micro- and nanofabrication for micro-electro-mechanical system (MEMS) technologies. In addition, the use of innovative materials and smaller low-power consumption silicon microheaters led to the development of high-performance gas sensors. Various heater layouts were investigated to optimize the temperature distribution on the membrane, and a suspended membrane configuration was exploited to avoid heat loss by conduction through the silicon bulk. However, there is a lack of comprehensive studies focused on predictive models for the optimization of the thermal and mechanical properties of a microheater. In this work, three microheater layouts in three membrane sizes were developed using the microfabrication process. The performance of these devices was evaluated to predict their thermal and mechanical behaviors by using both experimental and theoretical approaches. Finally, a statistical method was employed to cross-correlate the thermal predictive model and the mechanical failure analysis, aiming at microheater design optimization for gas-sensing applications.

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