Thin Film Based Micro-Machined Sensor Development and Mitigation of Process Challenges

2021 ◽  
Vol 23 (1) ◽  
pp. 44-46
Author(s):  
Kamaljeet Singh ◽  
◽  
S.V. Sharma ◽  
Keyword(s):  
Thin Film ◽  
Etch Rate ◽  
Back Side ◽  
Front Side ◽  
Wet Chemistry ◽  
Sensor Development ◽  
Close Vicinity ◽  
Mitigation Techniques ◽  
Differential Etching ◽  
Critical Aspects

Realization of thin film based sensor employing bulk micro-machined process using wet chemistry is challenging due to lateral etching phenomena. This phenomenon of convex corner undercutting is associated with wet micromachining process where differential etching is required. The challenge of having differential etching to achieve varied depth in close vicinity imposes extra constraint on the process. The present requirement simultaneously etching of closely spaced tunnel and cavity from back side having varied depth keeping intact front side layers is the main bottleneck which was circumvented with modified process. Etching trials related combining wet and dry etching techniques for deeper etching are also carried out and critical aspects are presented in this article. Another aspect is to define process steps compatible with CMOS integration. Further study of piezo-electric layer and etch rate of various deposited layer are also presented. This article details process trials, challenges, mitigation techniques and realization aspects of the micro-machined based sensor.

scholarly journals Effects of Thermal Annealing on the Characteristics of High Frequency FBAR Devices

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 397
Author(s):  
Yu-Chen Chang ◽  
Ying-Chung Chen ◽  
Bing-Rui Li ◽  
Wei-Che Shih ◽  
Jyun-Min Lin ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Annealing ◽  
Electromechanical Coupling ◽  
Zno Thin Films ◽  
Electromechanical Coupling Coefficient ◽  
Back Side ◽  
Zno Thin Film ◽  
Frequency Responses ◽  
Sputtering System

In this study, piezoelectric zinc oxide (ZnO) thin film was deposited on the Pt/Ti/SiNx/Si substrate to construct the FBAR device. The Pt/Ti multilayers were deposited on SiNx/Si as the bottom electrode and the Al thin film was deposited on the ZnO piezoelectric layer as the top electrode by a DC sputtering system. The ZnO thin film was deposited onto the Pt thin film by a radio frequency (RF) magnetron sputtering system. The cavity on back side for acoustic reflection of the FBAR device was achieved by KOH solution and reactive ion etching (RIE) processes. The crystalline structures and surface morphologies of the films were analyzed by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The optimized as-deposited ZnO thin films with preferred (002)-orientation were obtained under the sputtering power of 80 W and sputtering pressure of 20 mTorr. The crystalline characteristics of ZnO thin films and the frequency responses of the FBAR devices can be improved by using the rapid thermal annealing (RTA) process. The optimized annealing temperature and annealing time are 400 °C and 10 min, respectively. Finally, the FBAR devices with structure of Al/ZnO/Pt/Ti/SiNx/Si were fabricated. The frequency responses showed that the return loss of the FBAR device with RTA annealing was improved from −24.07 to −34.66 dB, and the electromechanical coupling coefficient (kt2) was improved from 1.73% to 3.02% with the resonance frequency of around 3.4 GHz.

ELECTRICAL BEHAVIOR OF A DOUBLE SIDED PV SOLAR PANEL

2011 ◽  
Vol 2011 (1) ◽  
pp. 000800-000804
Author(s):  
V. Ganescu ◽  
R. Shoaff ◽  
A. Pascu
Keyword(s):  
Thin Film ◽  
Power Output ◽  
Environmental Variables ◽  
Operating Conditions ◽  
Solar Panel ◽  
Back Side ◽  
Solar Pv ◽  
Electrical Behavior ◽  
Pv Module ◽  
Overall Efficiency

An innovative low power (5W) consumer grade dual face PV solar panel assembly is presented in this research. The authors propose capitalizing indirectly on the shadowed face of a typical solar panel by augmenting the panel’s total active area of exposure (via the panel’s “back side” and respective “deflectors”) and aiming at an increase in the overall efficiency of the assembly. Standard environmental operating conditions were taken into account. No CPV were used. The resulting power output profile of this unit is presented in detail and compared with the output of a single sided “standard” solar PV module configuration. In addition, under similar design and operating environmental variables, the behavior of crystalline cells panels is intended to be contrasted with thin film panels’ as variants of this proposed solution.

Study on Reactive Ion Etching of Vanadium Oxide Thin Film by Taguchi Method

2014 ◽  
Vol 909 ◽  
pp. 91-94
Author(s):  
Jun Gou ◽  
Hui Ling Tai ◽  
Jun Wang ◽  
De En Gu ◽  
Xiong Bang Wei ◽  
...  
Keyword(s):  
Thin Film ◽  
Taguchi Method ◽  
Vanadium Oxide ◽  
Etch Rate ◽  
Reactive Ion Etching ◽  
Oxide Thin Film ◽  
Optimum Process ◽  
Rf Power ◽  
Ion Etching ◽  
Vanadium Oxide Thin Film

A high selectivity patterning technology of vanadium oxide (VOx) thin film was suggested in this paper. VOxthin film was etched through a photoresist (PR) mask using Cl/N based gases in a reactive ion etching (RIE) system. Taguchi method was used for process design to identify factors that influence the patterning and find optimum process parameters. Experimental results suggested that RF power was the largest contribution factor for VOxetch rate, PR selectivity and uniformity on 6 inch diameter wafer. Uniformity and PR selectivity were improved by introducing a small amount of N2. High resolution and low roughness patterning transfer was achieved with a non uniformity of 2.4 %, an VOxetch rate of 74 nm/min, a PR selectivity of 0.96, a Si3N4selectivity of 5 and a SiO2selectivity of 10.

The Mechanism of J-V “Roll-Over” in CdS/CdTe Devices

2007 ◽  
Vol 1012 ◽  
Author(s):  
Jie Zhou ◽  
Xuanzhi Wu ◽  
Yanfa Yan ◽  
Sally Asher ◽  
Juarez Da Silva ◽  
...  
Keyword(s):  
Back Side ◽  
Back Contact ◽  
Front Side ◽  
Current Voltage

AbstractThe “roll-over” phenomenon in current-voltage (J-V) curves of CdS/CdTe devices is recognized as a result of the formation of a higher back barrier. When Cu has not been intentionally added to the back contact, roll-over is understandable. However, the mechanism was unclear for forming J-V roll-over in a CdTe cell with a back contact containing Cu. We did extensive characterizations, including XRD, XPS, SIMS, TEM, and EDS, and “recontact” experiments to understand this phenomenon. The results show that the roll-over comes from the formation of Cu-related oxides at the back side of the device during processing, rather than the diffusion of Cu to the front side of the device. Discussions related to the J-V roll-over mechanisms will also be presented.

A Novel Silicon Base Piezoresistive Pressure Sensor Using Front Side Etching Process

2003 ◽  
Author(s):  
Chih-Tang Peng ◽  
Ji-Cheng Lin ◽  
Chun-Te Lin ◽  
Kuo-Ning Chiang ◽  
Jin-Shown Shie
Keyword(s):  
Pressure Sensor ◽  
Thermal Loading ◽  
Fabrication Process ◽  
Back Side ◽  
The Novel ◽  
Front Side ◽  
Sensor Performance ◽  
Novel Structure ◽  
Piezoresistive Pressure Sensor ◽  
Packaging Structure

By applying the etching via technology, this study proposes a novel front-side etching fabrication process for a silicon based piezoresistive pressure sensor to replace the conventional backside bulk micro-machining. The distinguishing features of this novel structure are chip size reduction and fabrication costs degradation. In order to investigate the sensor performance and the sensor packaging effect of the structure proposed in this research, the finite element method was adopted for analyzing the sensor sensitivity and stability. The sensitivity and the stability of the novel sensor after packaging were studied by applying mechanical as well as thermal loading to the sensor. Furthermore, the fabrication process and the sensor performance of the novel pressure sensor were compared with the conventional back-side etching type pressure sensor for the feasibility validation of the novel sensor. The results showed that the novel pressure sensor provides better sensitivity than the conventional one, and the sensor output signal stability can be enhanced by better packaging structure designs proposed in this study. Based on the above findings, this novel structure pressure sensor shows a high potential for membrane type micro-sensor application.

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