A i L D i i d Ch i i f M O fAtomic Layer Deposition and Characterization of MgO fromAtomic Layer Deposition and Characterization of MgO from y p gMagnesium Bis(Di secbutylacetamidinate) and WaterMagnesium Bis(Di-secbutylacetamidinate) and WaterMagnesium Bis(Di secbutylacetamidinate) and Water

P de Rouffignaca N Sullivana D BeaulieuaP. de Rouffignac , N. Sullivan , D. BeaulieuJ -S Parkb A Hockc R G GordoncJ. S. Park , A. Hock , R. G. Gordon

aA di I S db MA USA diaArradiance Inc. – Sudbury, MA USA www.arradiance.comy,bSamsung Seoul KoreabSamsung – Seoul, Korea

cHarvard University – Cambridge MAHarvard University Cambridge, MA

INTRODUCTION Fil P tiINTRODUCTION Film PropertiesINTRODUCTION Film PropertiesM i id (M O) i d l hi h di l i i l 8 10 i h id M O d it d b th Si d l b b t t Th iti f thMagnesium oxide (MgO) is a moderately high dielectric constant material: 8-10, with a wide MgO was deposited on both Si and glassy carbon substrates. The composition of the g ( g ) y gband gap: 7 8 eV Potential applications include: gate insulator buffer layer for superconductors films was measured using Rutherford Backscattering spectroscopy. A typical RBS plot isband gap: 7.8 eV. Potential applications include: gate insulator, buffer layer for superconductors

d f l t i d hi h d l t i i fil f l di l M O h bfilms was measured using Rutherford Backscattering spectroscopy. A typical RBS plot is shown as well as a graph showing a decreasing O:Mg ratio with cycle numberand ferroelectrics, and high secondary electron emission film for plasma displays. MgO has been shown as well as a graph showing a decreasing O:Mg ratio with cycle number.

deposited via Atomic Layer Deposition using a variety of precursors1, however the full electrical Conformality was determined using fused silica capillary tubes and measuring the p y p g y p ,characterization of the material has yet to be published This work introduces the ALD of MgO

y g p y gpenetration of the film using an optical microscopecharacterization of the material has yet to be published. This work introduces the ALD of MgO

f M i Bi (Di b l idi ) d I ddi i h kpenetration of the film using an optical microscope

from Magnesium Bis(Di-secbutylacetamidinate) and water. In addition to the known 602 2

g ( y )applications ALD of MgO is an important component of Arradiance high gain microchannel

602.2Pure Mg(OH)2applications, ALD of MgO is an important component of Arradiance high gain microchannel

l t lifi d h lt t h l502

2, Å

g( )2

plate amplifiers and channeltron technology.40

1.8

OH

) 2

Rat

io

401 6 M

g(O

Mg

R

301 4

1.6

s of

M

to M

Precursor Synthesis and Properties 201.4

ness

gen Precursor Synthesis and Properties 20

1.2

hick

n

Oxy

g

101 Th

O

Pure MgO

Th i i dil th i d b th ti f i ll il bl dib t l 00 8

Pure MgO

The magnesium precursor is readily synthesized by the reaction of commercially available dibutyl 00.850 100 150 200 250 300 350

magnesium with the free amidine. The product is a colorless liquid which may be distilled at 80 Cycle Numbermagnesium with the free amidine. The product is a colorless liquid which may be distilled at 80 oC and 14mTorr The amidinate and precursor are a racemic and diastereomeric mixture with one

y

Increasing c cle n mber sho s decreasing O:Mg Ass ming e cess O isoC and 14mTorr. The amidinate and precursor are a racemic and diastereomeric mixture with one Increasing cycle number shows decreasing O:Mg. Assuming excess O is in the form of Mg(OH) the thickness of the h dro ide la er seems todominant diastereomer visible in the 1H NMR. in the form of Mg(OH)2, the thickness of the hydroxide layer seems to stabili e at 4nm of the total MgO film thicknessstabilize at ~4nm of the total MgO film thickness.

s-Bus-BuCHNN

CH3H

CH3

RBS of a 300cycle (24nm) MgO film on carbon CM

NH C

NCC

0.5 Mg(n-Bu)2CH3H2C

CH3 RBS of a 300cycle (24nm) MgO film on carbon. C and N <1%; composition is MgO1 3Al0 1

Mg CN

H3C CCCCH2 Glass capillary tube can be used to gauge the conformality of an ALDand N <1%; composition is MgO1.3Al0.1

Film density is 3 06 g/cm3 (similar to that reportedCH3NNBN N CC - 2 C4H10H3C

CH2 Glass capillary tube can be used to gauge the conformality of an ALD process In this case the film penetrated 620μm into a 14μm diameterFilm density is 3.06 g/cm (similar to that reported

by Burton et al of 3 07)1s-BuN N3

H HHprocess. In this case, the film penetrated 620μm into a 14μm diameter tube yielding an AR of 45by Burton et.al. of 3.07)s-BuH HH tube, yielding an AR of 45.

Electrical MeasurementsRacemic and diastereomeric mixture Electrical MeasurementsRacemic and diastereomeric mixture s-Bu = CH(CH3)(CH2CH3)

El i l d i NiC (4 5 10 3 2) IV i K i hl 2400 d Mi i l P b

( 3)( 2 3)Racemic and diastereomeric mixture Electrical measurements made using NiCr contacts (4.5 x 10-3 cm2). IV measurements using a Keithley 2400 and Micromanipulator Probe

t ti CV t i HP 4275 LCR t

Racemic and diastereomeric mixturestation, CV measurements using HP 4275a LCR meter

Electric Field (MV/cm)1.0E+00

Electric Field (MV/cm)

1 0E 011.50 2.50 3.50 4.50 5.50s-Bu = CH(CH3)(CH2CH3)

100nm NiCr1.0E-01

100nm NiCr1.0E-02

24nm MgO1.0E-03

1 5 SiO

24nm MgO1 0E 04m

2)

Si1.5nm SiO2

1.0E-04

s/cms-Bu = CH(CH3)(CH2CH3)

n-type Si1.0E-05

mps

B1.0E-06J

(am

s-Bu = CH(CH3)(CH2CH3)s-Bu = CH(CH3)(CH2CH3)

Contact evaporated from NiCr wire (80:20) yields an 1 0E-07

J

Minor ohmic contact with good adhesion. Si back contact.5% Residue1 0 08

1.0E 07Minorisomer

1.0E-08

1.0E-09

MgO shows low leakage and a rel. high breakdown field of ~5MV/cm.Th i t i l i f th d M (secB tAMD) Th 1H NMR t i di t th di till d t i l i f f

g g gThermogravimetric analysis of the crude Mg(secButAMD). T f 10 K i 1 i N fl 1

The 1H NMR spectrum indicates the distilled material is free of i i i i d l h h h i Electrical measurements of MgO thin films0.35Temperature ramp rate of 10 K min 1 in an N2 flow at 1 atm.

S l i i 0 GA h l id f hany organic impurities and also shows that the precursor is a

i f i d di h diff Electrical measurements of MgO thin films show a dielectric constant similar to that of0.30

m2Sample size is 50mg. TGA shows very low residue for the mixture of isomers and diastereomers. The different

show a dielectric constant similar to that of Al O ll l l k t0 25/c

mcrude product and <1% residue for the precursor after conformations should show similar surface reactivity.Al2O3, as well as, low leakage current d i i h l l k d i i0 20

0.25

μF/

distillation.densities. The low leakage current densities 0.20

ce,

are consistent with a material with a large ALD Growth Characteristics 0.15tan g

band gap (7.8 eV). CV measurements showALD Growth Characteristics 0.10paci

As-deposited 250C band gap (7.8 eV). CV measurements show well defined behavior and both V and0 05

0.10

Cap

As deposited 250C

400C 3hr Anneal well defined behavior and both VFB and h t i l t th t d id l th

0.05C 400C 3hr Anneal

hysteresis are closer to the accepted ideal than di l fil i

0.00

• All film depositions performed in an Arradiance GEM-D2 ALD system corresponding Al2O3 films on Si. Future -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00p p y• Films grown in a temperature range of 225 275 °C work will examine the electrical behavior of Gate Voltage (V) NiCr/24nmMgO/SiO2/Si• Films grown in a temperature range of 225 – 275 C

M i Bi (Di b l idi ) d i ultra thin (<10nm) MgO films within MIMDielectric constant pre-anneal is 9 8 including 16Å SiO2 (EOT =• Magnesium Bis(Di-secbutylacetamidinate) was used in a temperature ultra thin ( 10nm) MgO films within MIM and MIS devices

Dielectric constant pre anneal is 9.8 including 16Å SiO2 (EOT 11nm) and decreases to 5 5 after anneal VFB shifts from -0 7Vg ( y ) p

range of 105-118 °C and was directly dosed from a 150cc precursorand MIS devices.11nm) and decreases to 5.5 after anneal. VFB shifts from 0.7V

to +0 15V Hysteresis improves from 200mV to 20mVrange of 105 118 C and was directly dosed from a 150cc precursor d li b ttl

to +0.15V. Hysteresis improves from 200mV to 20mV.

delivery bottle Application of MgO Microchannel Plate Amplifiers• H2O was used as the oxidant at room temperature and was directly dosed Application of MgO – Microchannel Plate Amplifiers2 p y

to process chamber 8 000100000to process chamber6 920

8,000100000M 6,9207,000MgxAlx

6,000s10000AlxUncoated ,

Bia

s

Nominal Dose Exposure5,000

Volts

B

nPrecursor NominalPrecursor Temp

Dose Time

ExposureTime Purge Time 4,00000

Vo

1000

Gai

n

Precursor Temp Time Time3 000at

70G

H O 28 C 20ms 0 5s 70s3,000

Gai

n a

100H2O 28 C 20ms 0.5s 70s1 130

2,000G100

1,1301,000

Mg(secButAMD) 109 C 1s (x2) 1.5s 30s 1341,000

10g( ) ( )0

Uncoated Alx Mgx500 600 700 800 900 1000

Bi V Uncoated Alx MgxBias, V

Microchannel plate amplifiers are electron multipliers that can directly detect charged particles X Rays and UVMicrochannel plate amplifiers are electron multipliers that can directly detect charged particles, X-Rays, and UV. Wh l d ith h t th d it b d t d t t i ibl li ht d i tl iti l t fWhen coupled with a photocathode it can be used to detect visible light and is currently a critical component of

i h i i d i Th l d i l i i i d i450 night vision devices. They are also used extensively in mass spectrometers, imaging and spectroscopy in space, 1.00y = 0.789x - 0.7235400

and ion and electron microscopy. MCP treatment with high secondary electron emission film leads to a substantial, 0.95y 0.789x 0.7235R² = 0.9975

400 8-50X, gain increase over commercial lead glass MCPs. These devices exhibited extended lifetime and required a 0 900.95

le

350, Å reduced scrubbing dose for preconditioning to stabilize gain. This treatment can be used to revive aged MCPs. 0 850.90

cyc

300ess,

g p g g g0.85

Å/c

Conclusion250kne 0.80

e ,Å

Conclusion250

hick 0.75

Rat

e

200 Th

0.70h R

ALD th b h i f M O d t t d i l l til d li id M i Bi (Di150ilm 0.65wth

ALD growth behavior of MgO was demonstrated using a novel volatile and liquid precursor, Magnesium Bis(Di-b l idi ) Th M O fil h d d bl l l f C d N b h d ll f Al100

150Fi

0 600.65

row

secbutylacetamidinate). The MgO films had undetectable levels of C and N, but showed a small amount of Al as 1000 550.60G

a contaminant. Films exposed to air form a self-limiting hydroxide layer. Electrical measurements indicate the 50 0.55

film is a good insulator with a dielectric constant of 8-10. Application of MgO to Arradiance microchannel plate 00.50

amplifiers showed a substantial improvement in performance over existing commercial MCPs.0

0 100 200 300 400 500 600 200 225 250 275 300 p p p g0 100 200 300 400 500 600Cycle Number Growth Temp, °Cy

R fp,

Film thickness determined using spectroscopic ellipsometer . Å

ReferencesGrowth rate is relatively stable over the temperature range of 225 Index of refraction=1.74; Extrapolated growth rate = 0.8Å/cycle.

References– 275°C. Examination of of a larger temperature range is

No growth delay on UV-ozone treated Si. 1 Atomic Layer Deposition of MgO Using Bis(ethylcyclopentadienyl)magnesium and H2O; B B Burton D Ncurrently underway. Atomic Layer Deposition of MgO Using Bis(ethylcyclopentadienyl)magnesium and H2O; B. B. Burton, D. N. Goldstein and S M George J Phys Chem C 2009 113 1939–1946Goldstein, and S. M. George, J. Phys. Chem. C 2009, 113, 1939–1946

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