Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2001-08-30
2002-12-03
Loke, Steven (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S410000
Reexamination Certificate
active
06489648
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device, and more particularly to a semiconductor device using a material having a high dielectric constant.
With the progressive microminiaturization of components in semiconductor devices, of late it has been required that the gate of a transistor should be 0.15 &mgr;m in length and the gate dielectric film, if formed by SiO
2
, for example, should be made as thin as 2 nm or less in thickness.
With dielectric films having such a thin thickness, a tunneling current that passes through them is so large as not to be negligible. A possible solution to this problem has been considered to increase the physical thickness of the dielectric film while maintaining the dielectric properties by using a dielectric material having a higher dielectric constant than that of SiO
2
. Materials regarded as candidates for the above-mentioned material with high dielectric constant are zirconium oxide or hafnium oxide as is described in the 2000, February issue (pp.93-106) of Nikkei Microdevices, for example. However, zirconium oxide or hafnium oxide forms a layer of reaction compound with a thickness of about 1.5 nm ~2.5 nm at the interface with the silicon substrate as stated in the lecture papers (Lecture No. 6.1, pp.99-133, and Lecture No. 6.4, pp.145-148) of 1999 IEEE (THE INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS) INTERNATIONAL ELECTRON DEVICES MEETING, for example.
Such reaction compounds are likely to degrade electrical characteristics.
SUMAMRY OF THE INVENTION
The present invention has as its object to prevent deterioration of the electrical characteristics and provide a semiconductor device with improved reliability.
After assiduous efforts made to obtain measures by which to make it harder for oxygen to diffuse from a dielectric film that includes zirconium oxide as the cheif component element, the inventors have found it effective to add hafnium or titanium to the zirconium oxide.
On the other hand, from arduous endeavor to obtain measures by which to make oxygen less likely to diffuse from a dielectric film that includes hafnium oxide as the chief component element, the inventors have found it effective to add titanium to the hafnium oxide.
Moreover, the inventors have found that electrode materials, which have little tendency to allow oxygen to diffuse at the interface with the dielectric film that includes zirconium oxide or hafnium oxide as the chief component element, are cobalt silicide and silicon.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred and alternate embodiments.
REFERENCES:
patent: 6060755 (2000-05-01), Ma et al.
patent: 53-113484 (1978-10-01), None
patent: 2000-243951 (2000-09-01), None
“Devices Solution—LSI,”Nikkei Microdevices(Feb. 2000), pp. 93-106.
Byoung Hun Lee, et al., “Ultrathin Hafnium Oxide with Low Leakage and Excellent Reliability for Alternative Gate Dielectric Application,” IEEE International Electron Devices Meeting, No. 6.1 (1999), pp. 99-133 thru 99-136.
Wen-Jie Qi, et al., “MOSCAP and MOSFET Characteristics Using ZrO2Gate Dielectric Deposited Directly on Si,” IEEE International Electron Devices Meeting, No. 6.4 (1999), pp. 99-145 thru 99-148.
Benito deCelis, et al., “Molecular Dynamics Dimulation of Crack Tip Processes in Alpha-iron and Copper,”J. Appl. Phys.(Sep. 1983), 54(9):4864-78.
Thomas Kwok, et al., “Molecular-dynamics Studies of Grain-boundary Diffusion,”Physical Review B(May 15, 1984), 29(10):5363-71.
Ikeda Shuji
Iwasaki Tomio
Miura Hideo
Moriya Hiroshi
Hitachi , Ltd.
Loke Steven
Townsend and Townsend / and Crew LLP
Tran Thien F.
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