Harvard University

ALD of Manganese Silicate

Roy G. Gordon,1,2* Lu Sun,2 Qiang Chen,3 Jin-Seong Park4

and Sang Bok Kim1

1Department of Chemistry and Chemical Biology2School of Engineering and Applied Sciences

Harvard University, Cambridge, MA, USA3Beijing Institute of Graphic Communication, Beijing, China

4Hanyang University, Seoul, Korea

*Email: gordon@chemistry.harvard.edu

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Outline

2

Potential Applications of Manganese Silicate

ALD Process for Manganese Oxide, MnO

ALD Process for Manganese Silicate

Properties of Manganese Silicate

2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222

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Potential Applications of MnSixOy

barrier to diffusion of copper, water and oxygenadhesion promoter between copper and insulators nucleating layer for vapor deposition of copper

3

Copper wires in computer chips could use MnSixOy as a

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Manganese Precursors

4

N

NN

N

MnN N

NNMn

manganese(II) bis(N,N’-diisopropylpentamidinate)

manganese(II) bis(N,N’-di-tert-butylacetamidinate)

melting point: 60 °Cboiling point: 120 °C / 0.02 torr

melting point: 107 °Cboiling point: 100 °C/ 0.07 torr

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Saturation Curve for Manganese Oxide

5

0 4 8 12 16 20 24 280.0

0.2

0.4

0.6

0.8

1.0

1.2Th

ickn

ess p

er cy

cle (

A/cy

cle)

Mn-ipr ( mole/cycle)

200oC

N

NN

N

Mn

Saturated for doses > 10-5 moles/cycle

Co-reactant: water

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0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 5 10 15 20 250.0

0.2

0.4

0.6

0.8

1.0

Ref

ract

ive I

ndex

Refractive IndexThic

knes

s per

cycl

e (A

/cyc

le)

mole/cycle (10-6 mole/cycle)

Growth rate @ 200oC/85oC or 95oC

6

Saturation Curve for Manganese OxideSaturated for doses > 10-5 moles/cycle

N N

NNMn

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Thickness per Cycle for Manganese Oxide

200 240 280 320 3600.0

0.2

0.4

0.6

0.8

1.0

0.0

0.5

1.0

1.5

2.0

2.5

Thick

ness

per

cycle

(A/c

ycle)

Deposition temperature

growth rate# of cycle = 100095oC*3, H2O*2

Ref

racti

ve In

dex

Refractive Index

7

N

NN

N

Mn

nearly constant from 200 to 340 oC

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0 200 400 600 800 1000

A.U.

Channel (eV)

Data Simulation

Rutherford Backscattering Spectroscopy

Mn

O

Csubstrate

=> Stoichiometry MnO Adding O2 cycles => MnO2

8

Co-reactant: water

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0 200 400 600 800 1000

Mn 2p3

O 1s

Inten

sity (

A.U.

)

Binding Energy (eV)

Mn (2p3) : 641.9 eV O (1s) : 530.9 eV carbon-free : about 285 eV(after sputtering 1 min)

X-Ray Photoelectron Spectroscopy

9

< 1% C or N impurities

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XRD shows polycrystalline MnO

20 30 40 50 60

MnO(220)MnO(200)

Inten

sity

(A. U

.)

2

250oC MnOCubic structure

MnO(111)

10

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Precursors for Silicon and Oxygen

11

Si O

O

O

O

H

Si O

O

O

O

H

tris-tert-butoxysilanol (TBS) tris-tert-pentoxysilanol (TPS)

melting point: 63 - 65 °Cboiling point: 205 - 210 °C/ 760 torr

melting point: < 20 °Cboiling point: 96-99 °C/ 2-3 torr

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0 10 20 30 40 500

5

10

15

20

thic

knes

s (n

m)

cycles

ALD Conditions for Manganese Silicate

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Substrate: SiO2/SiUV ozone cleaning: 2 minDrying at 350°C: 1 hour

Mn amidinate source =105°CSi/O source (TPS)=120°C

T(substrate)= 350°C

Cycle times (s): 1/30/4/30 (Mn(amd)/purge/TPS/purge)

growth per cycle = 0.43 nm

High growth per cycle due to a catalytic mechanism similar to that of aluminum-catalyzed silica: Dennis Hausmann, Jill Becker, ShenglongWang, Roy G. Gordon, Science 298, 402 (2002)

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Saturation Curve for MnSixOy vs. Silicate Precursor

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0 2 4 6 8 10 12 14 16 18

0.30

0.35

0.40

0.45

0.50

0.55G

rowt

h ra

te (n

m/c

ycle

)

TPS doses

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TEM => Amorphous Structure

14

MnSixOy (35nm)

glue

Si

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STEM EDX Mapping of Elements

15

Mn

O

Si

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Composition by Rutherford Backscattering Spectroscopy

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Cycles Mn1015at/cm^2

Si 1015at/cm^2

O1015at/cm^2 Mn:Si:O

10 2.32 6.2 24 1 : 2.7 : 10

20 5.56 15 47 1 : 2.7 : 8

50 15.4 41 117 1 : 2.7 : 7.6

Stoichiometry ~ MnSi2.7O7.6 so Mn is oxidized to Mn4+

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Cu diffusion test

SiO22

Si

SiOCu 200 nm

8 nm10 nm

SiO22

Si

SiOMnSixOy

200 nm

8 nm

M Si O

Cu

visible appearance

anneal samples in N2 for 1h at 450 C, use Ni etchant to remove Cu film, then EDX

17

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CV tests after electric field at room temperature

10V for 1min

12V for 1min

15V for 1min

10V for 1min

12V for 1min

15V for 1min

15 nm

SiO22

Si

SiOMnSixOy

200 nm

60 nm

M Si O

Cu

SiO22

Si

SiOCu 200 nm

60 nm

18

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Effectiveness of MnSixOy as a Cu Diffusion Barrier

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Composition Structure Cu Barrier Diffusion PathwaySiO2 amorphous no open tetrahedral network

MnSi2.7O7.6 amorphous yes paths blocked by Mn ions

MnO polycrystalline no grain boundaries

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Acknowledgements

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Precursors supplied by Dow Chemical, Sigma-Aldrich and Strem Chemical

The work was supported as part of the Center for the Next Generation of Materials by Design, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science

Facilities at Harvard’s Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Infrastructure Network (NNIN), previously supported by the U. S. National Science Foundation