Electro-Ceramics Lab. Preparation and electrical properties of (Ba Preparation and electrical properties of (Ba 1-x 1-x ,Sr ,Sr x )(Ti )(Ti 1-y 1-y ,Zr ,Zr y )O )O 3 thin films for application at high density DRAM thin films for application at high density DRAM Sang-Shik, Park Dept. of Materials Engineering, Sangju National University, Sangju, kyungbuk, 742-711, Korea
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Electro-Ceramics Lab. Preparation and electrical properties of (Ba 1-x,Sr x )(Ti 1-y,Zr y )O 3 thin films for application at high density DRAM thin films.
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Electro-Ceramics Lab.
Preparation and electrical properties of (BaPreparation and electrical properties of (Ba1-x1-x,Sr,Srxx)(Ti)(Ti1-y1-y,Zr,Zryy)O)O33
thin films for application at high density DRAMthin films for application at high density DRAM
Sang-Shik, Park
Dept. of Materials Engineering, Sangju National University,
Sangju, kyungbuk, 742-711, Korea
Electro-Ceramics Lab.
OUTLINEOUTLINE
- High dielectric Constant
- Low leakage current density
- Fast dielectric response
▶ Requirements of capacitor for high density DRAM
Most promising dielectric material : (Ba1-x Srx )TiO3
BST films by CVD,PLD,Sputtering, MOD showed good properties
▶ Requirements of dielectric films for Gbit-scale DRAM application
≪ 25fF/cell in a cell size smaller than 0.1μm2 ≫ - Lower leakage current at thinner film
- Higher dielectric constant and lower loss compared to BST
Capacitance-voltage(a) and polarization-voltage(b) behaviorof BSTZ films as a function of chamber pressure.
-6 -4 -2 0 2 4 60.5
0.6
0.7
0.8
0.9
1.0(a)
50mTorr 30mTorr 10mTorr 5mTorr
C/C
ma
x
VOLTAGE(V)
-6 -4 -2 0 2 4 6
-30
-20
-10
0
10
20
30 (b) 50 mTorr 30 mTorr 10 mTorr 5 mTorr
PO
LAR
IZA
TIO
N(
C/c
m2 )
VOLTAGE(V)
Electro-Ceramics Lab.
Leakage current densityLeakage current density
Current-voltage(a) and current-E1/2 plot(b) of BSTZ films as a function of chamber pressure.
-400 -200 0 200 40010
-12
10-11
10-10
10-9
10-8
10-7
10-6
10-5
10-4
10-3
10-2
50mTorr
30mTorr
10mTorr
5mTorr
(a)
LEA
KA
GE
CU
RR
EN
T D
EN
SIT
Y(A
/cm
2 )
ELECTRIC FIELD(kV/cm)
0 10 2010
-12
10-11
10-10
10-9
10-8
10-7
10-6
10-5
10-4
10-3
10-2
(b) 50mTorr 30mTorr 10mTorr 5mTorr
LE
AK
AG
E C
UR
RE
NT
DE
NS
ITY
(A/c
m2 )
E1/2
(kV/cm)1/2
Electro-Ceramics Lab.
SummarySummary
(Ba1-x,Srx)(Ti1-yZry)O3 thin films were deposited by r.f. magnetron sputtering
Zr/Ti ratio of films decreased significantly with increasing chamber pressure. This variations affected microstructure and electrical properties.
▶when increasing chamber pressure - Decrease of Zr content - Decrease of Crystallinity - Increase of grain size and roughness - Increase of dielectric constant due to decrease of Zr - Increase of leakage current density
▶ Electrical properties of BSTZ thin films
- Dielectric constant and dissipation factor : 380~525 and 0.03~0.05 @ 100kHz - Leakage Current Density : 10-7 ~ 10-8A/cm2 order @ 200kV/cm - Paraelectric properties and schottky emission conduction
▶ BSTZ films appeared to be attractive for high density DRAM and should be further studied together BST.