ポストHfO2技術

希土類酸化膜

PVDデポ

15-3020-3010-1510-15

10-158-95-6k

Lanthanide OxidesHfSixOy

ZrO2, HfO2Al2O3

HfSixOyNzNO stackHfAlxOyMaterial

15-3020-3010-1510-15

10-158-95-6k

Lanthanide OxidesHfSixOy

ZrO2, HfO2Al2O3

HfSixOyNzNO stackHfAlxOyMaterial

Choice of high-kk value less than 50 is desirable forsuppression of short channel effects

High-k Gate Dielectric Candidates

●●●●

●●●● Gas or liquidat 1000 K

●●●●H

○○○○Radio activeHe

●●●● ●●●● ●●●● ●●●● ●●●● ●●●●Li Be B C N O F Ne①①①① ●●●● ●●●● ●●●● ●●●●Na Mg Al Si P S Cl Ar

②②②② ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●● ●●●● ●●●●K Ca Sc Ti V Cr Mn Fc Co Ni Cu Zn Ga Ge As Se Br Kr●●●● ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●●Rh Sr Y Zr Nb Mo Tc Ru Rb Pd Ag Cd In Sn Sb Te I Xe●●●● ③③③③ ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●● ●●●● ●●●● ①①①① ①①①① ○○○○ ○○○○ ○○○○Cs Ba ★★★★ Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○Fr Ra ☆☆☆☆ Rf Ha Sg Ns Hs Mt

○○○○La Ce Pr Nd PmSmEu GdTb Dy Ho Er TmYｂｂｂｂ Lu○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

★★★★

☆☆☆☆

Candidates Exp Reported

②

③

Unstable at Si interfaceSi + MOX M + SiO2①①①①

Si + MOX MSiX + SiO2

Si + MOX M + MSiXOY

●●●●

●●●● Gas or liquidat 1000 K

●●●●H

○○○○Radio activeHe

●●●● ●●●● ●●●● ●●●● ●●●● ●●●●Li Be B C N O F Ne①①①① ●●●● ●●●● ●●●● ●●●●Na Mg Al Si P S Cl Ar

②②②② ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●● ●●●● ●●●●K Ca Sc Ti V Cr Mn Fc Co Ni Cu Zn Ga Ge As Se Br Kr●●●● ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●●Rh Sr Y Zr Nb Mo Tc Ru Rb Pd Ag Cd In Sn Sb Te I Xe●●●● ③③③③ ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●● ●●●● ●●●● ①①①① ①①①① ○○○○ ○○○○ ○○○○Cs Ba ★★★★ Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○Fr Ra ☆☆☆☆ Rf Ha Sg Ns Hs Mt

○○○○La Ce Pr Nd PmSmEu GdTb Dy Ho Er TmYｂｂｂｂ Lu○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○

①①①① ①①①① ①①①① ●●●● ●●●●Rh Sr Y Zr Nb Mo Tc Ru Rb Pd Ag Cd In Sn Sb Te I Xe●●●● ③③③③ ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●● ●●●● ●●●● ①①①① ①①①① ○○○○ ○○○○ ○○○○Cs Ba ★★★★ Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○Fr Ra ☆☆☆☆ Rf Ha Sg Ns Hs Mt

○○○○La Ce Pr Nd PmSmEu GdTb Dy Ho Er TmYｂｂｂｂ Lu○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

★★★★

☆☆☆☆

CandidatesCandidates Exp Reported

②

③

Unstable at Si interfaceSi + MOX M + SiO2①①①①

Si + MOX MSiX + SiO2

Si + MOX M + MSiXOY

Other options?

R. Hauser, IEDM Short Course, 1999

Band offsets for High-k dielectrics on Si6

4

2

0

-2

-4

-6

1.1

3.52.4

0.3 -0.10.8 1.4 1.5

2.82.3 1.5

4.4

1.83.0

2.3

3.4 3.3 3.44.9

2.63.4

Si

SiO2

Si3N4

Ta2O5

BaTiO3

BaZrO3

ZrO2HfO2

Al2O3

Yb2O3

ZrSiO4

La2O3

2.3

2.6c

* C Estimates.

Ener

gy (e

V)

6

4

2

0

-2

-4

-6

1.1

3.52.4

0.3 -0.10.8 1.4 1.5

2.82.3 1.5

4.4

1.83.0

2.3

3.4 3.3 3.44.9

2.63.4

Si

SiO2

Si3N4

Ta2O5

BaTiO3

BaZrO3

ZrO2HfO2

Al2O3

Yb2O3

ZrSiO4

La2O3

2.3

2.6c

* C Estimates.

Ener

gy (e

V)

参考文献： J.Robertson Journal of Non-Crystalline Solids 303(2002) P98

Experimental data by XPS by Prof. T. Hattori

0 10 20 30 40 50Dielectric Constant

4

2

0

-2

-4

-6

SiO2

Ban

d D

isco

ntin

uity

[eV]

Si

kB *φ : Figure of Merit of High-kInsulating Films on Semiconductors Barcelona June 18-20, 2003

MBE装置

K-Cell × 2

Chamber堆積制御装置堆積制御装置堆積制御装置堆積制御装置

E-Gun 制御装置制御装置制御装置制御装置

Source × 4

Our Molecular Beam Deposition System

Back pressure: ~10-10 TorrDuring deposition:~10-9~10-7 Torr

Deposition rate:0.1~1 nm/min

IP

La2O3target

E-gun

Substrate

RP

Deposition Ch.

Loading Ch.

TSP

TMP

Transfer rod

n-Si

La2O3

Al

2 nm

n-Si

La2O3

Al

2 nm

Cross sectional TEM images for Al/La2O3/n-Si. 400oC depo., 400oC RTA in N2.

Physical thickness= 2 nm

EOT = 0.6 nm

Tox Electrical Equivalent vs. Current Density

From IEDM 2000, IEDM 2001, SSDM 2001 and VLSI Symp. 2001(Advanced Program)

10-10

10-6

10-2

102

0.5 1.0 1.5

HfO2NH3+HfO2HfSiONZrO2Zr-SilicateAl2O3NH3+ZrO2Zr-Al-Si-O

Pr2O3Nd2O3Sm2O3Gd2O3Dy2O3

Ta2O5NH3+Al2O3/ZrO2

La2O3SiO2Nitrided SiO2Tox Electrcal Equivalent (nm)

Curr

ent

Den

sity

(A/

cm2 )

23.326.127.09.6216.915.6

17.0

RelativeDielectri

cConstant

0.8080.7850.7840.3910.8700.823

0.806

Vfb[V]

0.1230.0810.083

-0.7000.2570.165

0.123

∆Vfb[V]

2.77e-67.27e-63.04e-71.37e-59.51e-73.09e-6

1.06e-2

Leakage

[A] @1VEOT[nm]

Annealing(5min)

1.280400oC1.443300oC

3.103400oC1.617300oC

200oC

200oC

1.106N2

1.762

1.760

O2

without

CalcfbsilicongateCalcfbfuncfittedfb VWWVWV ,,, +−=∆+∆=

0

1

2

-1.5 -1 -0.5 0 0.5

as-depo300℃400℃450℃

Cap

acita

nce

(µF/

cm2 )

Voltage (V)

10-8

10-6

10-4

10-2

100

102

-1 -0.5 0 0.5 1

Cur

rent

Den

sity

(A/c

m2 )

Voltage (V)

as-depo.

300 oC

400 oC

450 oC

Preliminary results

Dry N2 annealing

Densification: goodVfb shift: problemBeing solved by PM anneal

ID - VD Characteristics ( Lg = 2.5 µm )Chemical Oxide, Deposition Temp. = 250oC,

Lg = 2.5 µm, W = 27 µm, EOT = 3.0 nm

Lg

W

0

20

40

60

80

100

120

140

160

0 0.5 1 1.5 2 2.5 3 3.5 4

Dra

in C

urre

nt I D

(µA

/µm

)

Drain Voltage VD (V)

Vg = 0 V

Vg = 1.5 V

Vg = 1.0 V

Vg = 0.5 V

Lg/W = 2.5/27 µm

n+ Source n+ Drain

Gate

Deposition Temp. = 250oC, Tphy = 10 nm, Annealed

in O2 400oC 5min

5 nm

La 2O 3

Si-sub.

Al

Electrical Characteristics – Mobility µeff

100

1000

10-1 100

Effec

tive M

obilit

y µeff

(cm2 /V

-s)

Effective Field εeff

(MV/cm2)

La2O3 (EOT = 3nm)Universal Curve

High effective mobility of nearly the same to the universal curve was obtained with EOT = 3nm La2O3 gate dielectrics.

Flicker noise at Vds=100mV

10-23

10-22

10-21

10-20

10-19

10-18

10-17

101 102 103 104

1μA2.5μA5μA10μA25μA50μA100μA

S ID (A2 /Hz)

Frequency (Hz)

WｘL=27μmｘ2.5μm

1/f

Results and Discussion (6)LF Noise – Comparation with SiO2

1.E-13

1.E-12

1.E-11

1.E-10

1.E-09

1.E-08

1.E-01 1.E+00 1.E+01 1.E+02 1.E+03

f=100Hzf=100Hzf=100Hz

(gm/Id)2 (V-2)10-0 101 102 10310-1

10-9

10-10

10-11

10-12

10-13

10-8

S ID/I d2

(1/H

z)

La2O3 (WL=27µmx2.5µm)SiO2 (WL=50µmx2.5µm)

La2O3 (WL=54µmx2.5µm)

f = 100HzVd = 0.1V

The normalized noise spectrum of n-type MISFET’s with La2O3gate dielectrics is about one order in magnitude higher than that of SiO2 obtained from thermal oxidation.

The oxides become hydroxide and carbonate in H2O and CO2ambient.

Absorption of moisture and CO2

Ln2O3

n-Si(100)

Ln2O3

n-Si(100)

Ln2(CO3)3

Ln2O3 + H2O → Ln2O3・H2O

Ln2O3 + H2O → 2(LnOOH)

2Ln(OH) + H2O → 3Ln2(OH)3

Ln2O3

n-Si(100)

Ln2(OH)3

n-Si(100)

Ln2O3 + 2CO2 →Ln2(CO3)3

hydroxide carbonate

※Ln：Lanthanide

Experimental apparatusTemperature: ~20oCHumidity: 80%Humidification time:

0 ~120 hrs

ThermometerHygrometer

Samples

Ultra pure water

acryl(PMMA)or glass(PYREX)

*PMMA : CH2C(CH)3COOCH3

glass(PYREX)

acryl(PMMA)

1Yb2O3Gd2O3Dy2O3

ZrO2SiO2

1 2Lu

2O

3Eu

2O

3Sm2O3

Pr2O

3La

2O

3

CET120hrs

/CETfresh

CET

120hrs /CET

Fresh

Change of CET for all studied

Absorption test in case of acryl apparatus

after the Al electrode formation for Pr2O3.

n-Si(100)

Al electrode

High-k film

moisture

with electrode C-V

n-Si(100)High-k film

～～ ～～ ～～ ～～～～ ～～

0

0.5

1

1.5

-2 -1 0 1

Fresh24hrs (with electrode)

Cap

acita

nce

(µF/

cm2 )

Voltage (V)

Pr2O3 / n-Si(100)

R.T.-depo

RTA : N2600oC

研究目的

Lu2O3

La2O3

Si

Lu2O3

Si

La-Silicate

Si

Lu2O3

Si

silicate

phase separate

SiO2

RTA

RTA

Ref. S.Ohmi, et al., J. Electrochem. Soc., 150, F134(2003)H.Nohira et al., J. Appl. Surf. Sci., 216(2003)

La2O3

Lu2O3

La2O3

Si

Lu2O3

Si

La-Silicate

Si

Lu2O3

Si

silicate

phase separate

SiO2

RTA

RTA

Ref. S.Ohmi, et al., J. Electrochem. Soc., 150, F134(2003)H.Nohira et al., J. Appl. Surf. Sci., 216(2003)

La2O3

Lu2O3

Si substrate

La2O3

RTALu2O3

La-Silicate

Stack(Lu2O3/La2O3)

La2O3で界面層成長と微結晶化を抑えるLu2O3で膜全体silicateを抑え、耐湿性を向上 誘電率を保ちつつリーク電流を抑制

µeff = 163 [cm2V-1s-1] (EOT = 2.05 nm)

0

10

20

30

40

50

0 1 2

I D [µ

A/µ

m]

VD [V]

W = 54 µm

-0.5V

VG = 1.1V

0.9V

-0.1V

L = 10 µm

0.7V

0.1V0.3V

0.5V

-0.3V

dott line : La

2O

3

10-8

10-7

10-6

10-5

10-4

10-3

0

0.5

1

1.5

2

2.5

3

-1.5 -1 -0.5 0 0.5 1I D

[A]

g m [µ

S/µm

]

VG [V]

W = 54 µm

S = 80 mV/dec

L = 10 µm Vd = 0.1 V

dott line : La2O3

S = 160 mV/dec

積層構造(Lu2O3/La2O3/n-Tr)の作製

ID-VD Characteristics ID - VG Characteristics

nMIS 250oC堆積, annealed at 400oC, Al電極を使用

O2300→O2400でより改善がみられ、同条件のLa2O3と比較して、良好な特性が得られた

Lu2O3のののの耐湿性耐湿性耐湿性耐湿性によりによりによりにより、、、、電気特性電気特性電気特性電気特性がががが改善改善改善改善したしたしたした

Conduction Modes and Expressions

*Thermionic Current, **Direct Tunneling Current,***Space-Charge-Limited Current : single trap level for shallow (7) and deep (8) distributio

Mode

Bulk-

Limite

d

Expression

DT**F-N

Schottky*

Poole

SCLC***

( ) 21ln EJ ∝( ) EJ ∝ln

( ) TTJ 1ln 2 −∝

( ) EEJ 1ln 2 ∝(weak) TJ 2∝

EJ ∝

( ) TJ 1ln −∝( ) EEJ ∝ln

(1)(2)(3)

(5)

(6)(7)

2EJ ∝(8)

Bulk-

Free

( ) E J αln

P-F ( ) 21ln EEJ ∝

(4)Ohmic ( ) TJ 1ln −∝

Al Electrode Case – Leakage Current

Q.EOT 1.54 nmO.TOX 4.7nmRDC 11.9

-2 -1 0Vg [V]

0.0

500.0n

1.0u

1.5u

2.0u

Cg [F

/cm^2

]

1MHz(R)1MHz(F)HF

Cg [F

/cm2 ]

Measured

Calculated

1E-05

1E-04

1E-03

1E-02

-1.0 -0.5 0.0 0.5 1.0Vg [V]

|Jg| [A

/cm2 ]

J0J40J80OV0OV40OV80SQS0SQS40SQS80PF0PF40PF80

0 oC40 oC80 oC

Ohmic

P-F

VFB VG=0V

ReverseField

SCLC(Shallow)

2003.11.30.修正

Conduction Band

Valence Band

5.5eV

0.22-0.24 eVTrap Level

300K

SCLC Conduction (Ag) : Shallow Trap DistributionPoole-Frenkel Conduction (Al)

La2O3

超高真空アニール後のLa2O3薄膜中のトラップ準位