Development of Hig-Sensitive Pressure Sensors Using Screen Prenting Method

1994 Fiscal Year Final Research Report Summary

• Project/Area Number: 05555097
• Research Category: Grant-in-Aid for Developmental Scientific Research (B)
• Allocation Type: Single-year Grants
• Research Field: 電子デバイス・機器工学
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: ISHIWARA Hiroshi Tokyo Institute of Technology・Precision and Intelligence Laboratory, Professor, 精密工学研究所, 教授 (60016657)
• Co-Investigator(Kenkyū-buntansha): IWATA Yoshinori Oval Corp.Reserach Lab., Researcher, 研究2課, 研究員 ; AIAWA Kouji Tokyo Institute of Technology・Precision and Intelligence Laboratory, Research As, 精密工学研究所, 助手 (40222450)
• Project Period (FY): 1993 – 1994
• Keywords: Pressure Sensor / Semiconductor / CdS / Diaphragm / Sereen Printing / Glass Film

Research Abstract

In the first year, diaphragm-type pressure sensors have been fabricated on Si substrates using a screen printing method, in which some refractory glass films have been tried and AFS 1880 glass by Asahi Glass Corp. has been selected. It was found under the optimization conditions that the flatness of the glass surface was less than <plus-minus> 0.2mum for 30- to 40- mum- thick films, when the glas films were spin-coated with SiO_2 films. Then, in order to fabricate diaphragms, the Si substrates were successfully etched in 1.2mm square using KOH solution. On these diaphragms, poly-Si films were deposited and resistors were fabricated in order to check the refractive properties of the diaphragms. It is concluded from these experiments that there is no damage on the diaphragms, if the process temperature is lower than 600ﾟC.
In the second year, screen printing of CdS films on SiO_2-coated Si substrates was carried out. The starting material was CdS paste which was composed of CdS powder, CdCl_2 flux (12wt%) , and propyleneglycol binder. The paste was printed through metal mesh and baked in an electric furnace at temperatures high than 420ﾟC.It was also found from X-ray diffraction analysis that polycrystalline CdS films were formed at temperatures higher than 470ﾟC.It was also found from van der Pawu measurements that electrical conduction of the films was observed at temperatures ranging from 520ﾟC to 620ﾟC and from SIMS measurement that Cl dopants in the films decreased at higher temperatures.
From these results, we conclude that semiconducting CdS films can be formed using the screen printing method on glass diaphrabms on Si substrates. The process temperature is expected to be lower than 600ﾟC in this method.