Michel Billaud, Tlionias Zimmer, Didier Geoffroy, Yves Danto. Universitk Bordeaux I. 351, cows de ... Hans Effinger, Wilhelni Seifert. Fuchbereich Elektrotechnik ...
Fourth IEEE International Caracas Conference on Devices. Circuits and Svstems. Aruba. Anril 17-19. 2002
REAL MEASURES, VIRTUAL INSTRUMENTS Michel Billaud, Tlionias Zimmer, Didier Geoffroy, Yves Danto Universitk Bordeaux I 351, cows de la Libkration, 33405 Talence Cedex, France e-mail :bilIuud@,labi-i,u-bordeaux.fi Hans Effinger, Wilhelni Seifert Fuchbereich Elektrotechnik, Fuchhochschule Muenster Stegerwaldstr. 39, 48565 Steinfiirt, Germany Javier Martinez, Francisco Gomez
UAM - Laboratorio de Microelectronica, ETS de Informatica, Facultad de Ciencias C-XI 1a Planta Cantoblanco, 28049 Mudrid, Spain Abstract. This paper presents the realisation of a remote lab on a European scale. The involved countries are France, Germany, and Spain. The architecture of the lab is described and the functionality has been tested. It concerns the instrumentation in the field of microelectronics. It has been applied to the characterisation of MOS transistors.
1. Introduction Recent advances in Internetiweb technologies and computer-controlled instrumentation permit net-based techniques to be utilised for setting up remote laboratory access to advanced instrumentation. In this context, the University Bordeaux 1, France, has realised a project called RETWINE. Retwine stands for REmoTe Worldwide Instrumentation NEtwork. This has been done in the framework of European Community SOCRATES - MINERVA program. The partners involved in this program are: the Fachhochschulc of Munster, Germany, and the University of Madrid, Spain. This tool permits the use of powerful instruments via the World Wide Web. The first part of this paper gives an overview of the RETWINE architecture. The second part describes how this tool can bc used. We present an application concerning a characterisation of MOS transistors. The last part providcs a discussion and gives further perspectivcs.
2. RETWINE Implementation The aim of thc RETWINE tool is to provide the use of advanced mcasurcment instruments via the Web based on the client-scrver technology.
0-7803-7380-4102/$17.00 0 2002 IEEE
On the client side, the user interface (UI) is required to mimic the real measurement instrument (MI). Also the U1 has to run on an heterogeneous network of computers (Windows, UNIX, ...) with no prior specialised software installation required. Under these constraints, the choice of Java Applets is quite natural, as Web browsers (Internet Explorer, Netscape ...) are usually already installed in the student computer rooms.
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The generic architecture is described in figure 1. I
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Fig. 1: Description of the generic “RETWINE” architecture
- Web servers (in Madrid, Munster and Bordeaux) provide HTML pages (general information, course texts, lab exercises) and Java applets for the instruments. - Each Java applet shows the front panel of a MI, with active zones (for keys and switches) together with other user interfaces components (for example cascaded “softkeys“ menus). User actions on these components change the internal state of the U1 (selecting measurement modes, turning leds odoff, changing menu labels ...) and/or send action requests to the Web server (via an HTTP-Url-Connection).
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- On the Web server these actions launch a CGI scripts that ask the instrumentation server to send a command to the MI via the GPIB IEEE-488 interface. In the case of measurement commands, the instrument driver (a small program in C) also stores the experimental data on the Web server, so it can be retrieved and displayed later via a specialise plotting applet. - A visual feedback is also provided by means of
WebCams connected to a “video server“. Screenshots show the students what really happens on the MI screen, and proves helpful for remote troubleshooting (is the MI really on ?)
Implementation of RETWINE in Bordeaux In the Bordeaux part of RETWINE (figure 2) the same computer (SUN Sparc ULTRA 5/10 SunOS 5.7) plays both roles of Web server (running Apache 1.3.12) and instrument server (using a National Instruments IEEE488 interface card). 2.1
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A similar RETWINE implementation had been realised in Madrid and Munster. Slight differences like the used operating systems, the handling of simultaneous requests, the instrument reservation system etc.. . exist and are explained in [I].
3. Application to MOS transistor characterisation
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The devices under test
To validate the RETWINE tool MOS transistors had been tested. C(V) measurements had been performed on a specific test structure, where gate oxide thickness and substrate doping can be extracted. Finally, from measured DC characteristics a complete characterisation of the MOS transistors can be performed.
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2.2 Implementation of RETWINE in Madrid and Munster
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Web Server / instrument server
Video server
The camera server is a PC under Linux Mandrake 6.0, with a kemel version 2.2.16, with the 0 ~ 5 1 1driver supporting 2 USB WebCam3 USB (from Creative Labs), one for the HP 4194A and one for the HP 8510B. lt also supports a Meteor I1 (Matrox) framegrabber card for the SONY CCD camera attached to the PA 200 prober bench.
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Suss PA 200
3.2
The virtual lab
To perform the specific measurements, C(V) and DC measurements have to be performed, as already mentioned. Figures 3 and 4 show the front panel of the HP4284 precision LCR meter (used for C(V) measurements and of the HP4 155 Semiconductor parameter analyser (used for DC measurements). The HP4284 is located in the University of Madrid, the HP4155 is located in the Fachhochschule Munster. The access to this instruments, as well as a detailed description how to use, is found on the web-page [I]. The devices had been sent to the partners labs by post mail.
Fig. 2: Description of the Bordeaux specific “RETWDTE” architecture The local instrumentation pool used by students consists of a HP4149A impedance and gaidphase analyser (Hewlett Packard) and a HP8510B network analyser (Hewlett Packard). User Interfaces have also been developed for some other instruments : a Tek 1 1802B Oscilloscope (Tektronix)(under construction), and a Suss PA 200 Prober Bench (Suss Microtec).
Fig 3: HP4284 precision LCR meter
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I k V S U B = -1 v 4 V S U B = -2 v +VSUB = -3 V
Fig 4: HP41 55 Semiconductor parameter analyser
3.3
Measurements
3.3.1 C(V) measurements The measurement conditions are the following : CP-RP Impedance measurement : DC-Bias : on 1MHz Spot frequency : Osc-Level : 30mV Variation of DC Bias from -5V to + 5V. The result is put on view in figure 5 for the Cp value. The measurements has been performed in Bordeaux, France. The instrument and the device were located in Madrid.
Fig. 5 : C(V) behaviour of the MOS-capacitor
3.3.2 DC measurements The following stimuli give the transfer characteristics from figure 6 : VDS=I OOmV, VGS=O., .SV, VSUB=O ...A. The output characteristic is represented on figure 7. The corresponding stimuli are: VDS=O. ..5V, VGS=2V, VSUB=OV. The measurements has been performed in Bordeaux, France. The instrument and the device for DCmeasurements were located in Munster.
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Fig 6 : ID as a function of VGS for different VSUB, VDS=const
3.3.3 Measurement data analysis After measurements the data are analysed. e.g. from C(V) measurements, the gate oxide thickness and substrate doping are determined. Finally, from measured DC characteristics a complete characterisation of the MOS transistors is performed. Electrical parameters like electron surface mobility, threshold voltage, body effect parameter and output conductance are extracted.
4. Conclusion We implemented a tool which allows the use of advanced instruments via the Web. The results presented in this paper indicate that: the realisation is possible
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internet connection problems occur sometimes, be patient the access to advanced instrumentation is available in a cost-effective manner,
6. Acknowledgements We would like to thank the European Commission for financial support via the Socrates-- Open and Distance Learning program.
5. Perspectives Bringing together the experiences from the described RETWINE project, from the Lab-on-Web project [ 2 ] and similar other remote lab projects, where prototypes of remote laboratories were realised and successfi~lly demonstrated, can result in an innovative and advanced network structure that will permit the dissemination of real laboratory experiments to support engineering and science within the world.
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References
[I]
http://www.retwine.net
121 www.lab-on-web.com
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