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Strontium titanate thin films for ULSI memory and gate dielectric applications.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Strontium titanate thin films for ULSI memory and gate dielectric applications./
Author:	Lee, Jian-Hung.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2000,
Description:	109 p.
Notes:	Source: Dissertations Abstracts International, Volume: 62-06, Section: B.
Contained By:	Dissertations Abstracts International62-06B.
Subject:	Electrical engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9983272
ISBN:	9780599898684

Strontium titanate thin films for ULSI memory and gate dielectric applications.
Lee, Jian-Hung.

Strontium titanate thin films for ULSI memory and gate dielectric applications. - Ann Arbor : ProQuest Dissertations & Theses, 2000 - 109 p.

Source: Dissertations Abstracts International, Volume: 62-06, Section: B.

Thesis (Ph.D.)--The University of Texas at Austin, 2000.

This item must not be sold to any third party vendors.

Strontium titanate (ST) was investigated for both high-density memory and gate dielectric applications. Although barium strontium titanate (BST) has been more widely studied as the dielectric of future DRAM storage capacitors, its thickness dependence of the dielectric constant might restrict its application in the lower thickness regime. On the contrary, the permittivity of strontium titanate decreases with thickness at a much slower rate than that of barium strontium titanate. Therefore, the permittivity difference between ST and BST may be negligible when the film thickness is lower than 50 run. Besides, the advantage of ST over BST includes complete paraelectricity and process simplicity. ST on platinum (Pt) substrates has been reported to be too leaky for ULSI DRAM applications. However, the leakage can be greatly improved from 3 x 10−6 to 5 x 10−8 A/cm2 ( 1V) by replacing Pt with iridium (Ir) as the bottom electrode. Also, the dielectric constant is higher for ST on Ir (ϵ r = 237 for ST/Ir vs. (ϵr = 160 for ST/Pt) because the crystallinity is enhanced by iridium oxide that forms during the deposition. Resistance degradation is a serious reliability issue in Perovskite titanate films, and ST is no exception. In this dissertation, efforts were made to curtail the rate of resistance degradation by doping the ST films with niobium (Nb). It is generally believed that resistance degradation is caused by oxygen vacancies in the films. Nb might reduce the number of oxygen vacancies due to its high valence charge. Our experimental results showed that the degradation rate could be reduced by approximately four times with Nb atomic fraction = 0.01. ST was also studied as a high-k material for the gate dielectric. Pt and titanium nitride (TiN) were used as the top electrodes. This work focused on its dielectric and electrical characteristics as functions of temperature and external applied voltages. Since an interfacial amorphous oxide formed between ST and the silicon (Si) substrate, we could model the stack capacitor with three capacitors and three resistors. The capacitance as a function of frequency agrees well with the equivalent circuit model.

ISBN: 9780599898684Subjects--Topical Terms:

649834
Electrical engineering.
Subjects--Index Terms:

Gate dielectric

Strontium titanate thin films for ULSI memory and gate dielectric applications.
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020 $a 9780599898684
035 $a (MiAaPQ)AAI9983272
035 $a AAI9983272
040 $a MiAaPQ $c MiAaPQ
100 1 $a Lee, Jian-Hung. $3 3687154
245 1 0 $a Strontium titanate thin films for ULSI memory and gate dielectric applications.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2000
300 $a 109 p.
500 $a Source: Dissertations Abstracts International, Volume: 62-06, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Lee, Jack C.
502 $a Thesis (Ph.D.)--The University of Texas at Austin, 2000.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a Strontium titanate (ST) was investigated for both high-density memory and gate dielectric applications. Although barium strontium titanate (BST) has been more widely studied as the dielectric of future DRAM storage capacitors, its thickness dependence of the dielectric constant might restrict its application in the lower thickness regime. On the contrary, the permittivity of strontium titanate decreases with thickness at a much slower rate than that of barium strontium titanate. Therefore, the permittivity difference between ST and BST may be negligible when the film thickness is lower than 50 run. Besides, the advantage of ST over BST includes complete paraelectricity and process simplicity. ST on platinum (Pt) substrates has been reported to be too leaky for ULSI DRAM applications. However, the leakage can be greatly improved from 3 x 10−6 to 5 x 10−8 A/cm2 ( 1V) by replacing Pt with iridium (Ir) as the bottom electrode. Also, the dielectric constant is higher for ST on Ir (ϵ r = 237 for ST/Ir vs. (ϵr = 160 for ST/Pt) because the crystallinity is enhanced by iridium oxide that forms during the deposition. Resistance degradation is a serious reliability issue in Perovskite titanate films, and ST is no exception. In this dissertation, efforts were made to curtail the rate of resistance degradation by doping the ST films with niobium (Nb). It is generally believed that resistance degradation is caused by oxygen vacancies in the films. Nb might reduce the number of oxygen vacancies due to its high valence charge. Our experimental results showed that the degradation rate could be reduced by approximately four times with Nb atomic fraction = 0.01. ST was also studied as a high-k material for the gate dielectric. Pt and titanium nitride (TiN) were used as the top electrodes. This work focused on its dielectric and electrical characteristics as functions of temperature and external applied voltages. Since an interfacial amorphous oxide formed between ST and the silicon (Si) substrate, we could model the stack capacitor with three capacitors and three resistors. The capacitance as a function of frequency agrees well with the equivalent circuit model.
590 $a School code: 0227.
650 4 $a Electrical engineering. $3 649834
650 4 $a Materials science. $3 543314
650 4 $a Condensation. $3 942542
650 4 $a Condensed matter physics. $3 3173567
653 $a Gate dielectric
653 $a Strontium titanate
653 $a Thin films
653 $a ULSI
690 $a 0544
690 $a 0794
690 $a 0611
710 2 $a The University of Texas at Austin. $3 718984
773 0 $t Dissertations Abstracts International $g 62-06B.
790 $a 0227
791 $a Ph.D.
792 $a 2000
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9983272