Resistivity annealing properties of aluminium thin films after ion implantation at liquid helium temperatures

HAL Id: jpa-00231215

https://hal.archives-ouvertes.fr/jpa-00231215

Submitted on 1 Jan 1975

HAL is a multi-disciplinary open access

archive for the deposit and dissemination of

sci-entific research documents, whether they are

pub-lished or not. The documents may come from

teaching and research institutions in France or

abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est

destinée au dépôt et à la diffusion de documents

scientifiques de niveau recherche, publiés ou non,

émanant des établissements d’enseignement et de

recherche français ou étrangers, des laboratoires

publics ou privés.

Resistivity annealing properties of aluminium thin films

after ion implantation at liquid helium temperatures

A.M. Lamoise, J. Chaumont, Frédéric Meunier, H. Bernas

To cite this version:

RESISTIVITY

ANNEALING

PROPERTIES

OF ALUMINIUM THIN

FILMS

AFTER ION

IMPLANTATION

AT

_LIQUID

HELIUM

TEMPERATURES

_(*)

A. M. LAMOISE and J. CHAUMONT

Laboratoire René Bernas du

Centre de

_{Spectrométrie}

Nucléaire et

_{Spectrométrie}

de

Masse,

91406

_Orsay,

France

F. MEUNIER

Laboratoire de

_Physique

des Solides

_(**)

Université

Paris-Sud,

91406

_Orsay,

France

H. BERNAS

Institut de

_Physique

Nucléaire,

Université

Paris-Sud,

91406

_Orsay,

France

(Re~u

le

_{9 juillet}

_1975,

_accepte

le 26

_septembre

₁₉₇₅₎

Résumé. 2014 Nous

présentons les

_premiers

_{résultats de recuit de résistivité pour des couches minces} d’aluminium

_après

_implantation d’ions Al, H et O à des _{températures} inférieures à 6 K. La courbe de recuit après

implantation

d’ions Al est semblable à celle obtenue

_après

irradiation aux neutrons.

L’implantation d’ions H à faible dose fait

_apparaitre

deux _pics très _marqués au stade I du recuit.

Après

implantation de fortes doses _{d’hydrogène,} la courbe de recuit indique la

_possibilité

d’un ordre des ions H ou bien d’une transformation de _phase.

Abstract. 2014 We

present the first _{resistivity annealing} curves of Al after

_implantation

of _Al-, H-,

and O-ions at _liquid helium _{temperatures.} The _{Al-implantation produces} a curve _resembling that

of neutron-irradiated _{Al ;} low-dose H-

_implantation

results in two _strongly enhanced _stage I recovery

peaks, while _high-dose H-

_implantation

_annealing results _suggest that _H-ordering or a _phase trans-formation takes

_place.

Classification

Physics Abstracts

7.188 - 8.362

Although

ion

_implantation

in metals is a

well-developed technique

[1],

the standard

_techniques

of radiation

damage physics

have not yet all found their

application

in this field. This is of course due to the

relatively

low

_{implantation energies : typical}

_range

profiles

rarely

go

beyond ~

1 000

A

so that

samples

must be made of thin films in order to use

_techniques

such as

_resistivity

measurements with a reasonable

signal-to-noise

ratio.

Moreover,

it is often necessary

to

_operate

at low

_temperatures

and

_implantation

conditions are in

general

rather unfavourable for

such

_experiments.

Another

_{prejudice against}

resis-tivity

measurements on

_implanted

metal thin films

was that since the film thickness is of the order of the

conduction electron mean free

_path,

the

resistivity

change

due to radiation-induced defect

_annealing

would be washed out

_by

the size effect of the film.

We have set _up a

_liquid

He cryostat on the

_Orsay

ion

implantor,

and have

_equipped

it so that

_reasonably

accurate

_resistivity

_annealing

_experiments

can be

carried out on

_implanted

metallic thin films. In this

paper, we

_present

our first results on

_{ion-implanted}

Al

films. In order to determine the effect of ion-induced radiation

_{damage alone,}

Al was

_implanted

into Al at

fairly

low doses. H-

_implanted

Al

_(again

at low

_dose)

provided

information on the

_annealing

_spectrum

of interstitials. Because of their

_interesting

super-conducting

properties [2]

the

_{resistivity annealing}

of the concentrated Al-H systems was also measured.

Finally,

in a search for chemical

_effects

related to

oxide

formation,

we have studied the

resistivity

annealing

of concentrated 0-

_implanted

Al. The results on the various

samples

are

_strikingly

different,

and indicate that

_{resistivity annealing experiments}

can

_be,

_quite

useful in

_{understanding}

the

_properties

of

_implanted

metals and

_alloys.

The

_experimental

_arrangement and film

_preparation

L-306 JOURNAL DE _{PHYSIQUE -} LETTRES

technique

are

_briefly

summarized in

_[2],

and will be described in detail elsewhere. The aluminium films

(typically

10 x 0.3

mm2,

thickness 1 300-1 650

_A)

were

prepared

by

Al

evaporation

on

crystalline

quartz

substrates in a standard

_bell-jar

vacuum.

Their

_resistivity

ratio

_p(300

_K)/p(4.2

_K)

was about 2.7.

Resistivities were measured

_using

a standard

four-point probe

technique,

and size and

_impurity

effects

were normalized out

_by

simultaneous measurement of the

_{implanted sample}

and of an identical film mounted

in the _cryostat at the same

time,

but shielded from the

ion beam. Al-

_implantation

was carried out at a

single

energy

(100

keV-Al).

Using

standard

slowing-down

_{theory [3],}

the _range and _range distribution are

estimated at 1 200

A

and 400

_A,

_{respectively.}

For the 1 500

A -

thick film used in this case, this

produces

a

_sample

which has been

_{implanted throughout.}

The measured

_resistivity

is of course an _average, since

the defect

_depth

distribution is

_{approximately}

gaus-sian. We also find that the

_resistivity

increase is not

proportional

to the dose.

_Although

this

_prevents

precise

absolute measurements, it still allows better than

_{order-of-magnitude}

values of the radiation induced

_resistivity

increment to be

obtained,

as well

as accurate relative

_{resistivity annealing}

measure-ments. For the

_lightest

ions

_(especially

H and

_D),

the _range

_parameters

are

_subject

to

_larger

uncertainties

and

the _range distributions are

_relatively

narrower

_[4].

Hence

_(i)

in order to obtain more

_{uniform samples,}

two or three

_{implantations}

_(at

different

_energies)

had to be carried _out, and

_(ii)

an

_approximate

total absolute

_resistivity

increase was deduced from the

values measured after the last of the successive

implan-tations. For

_example,

in the case of a

_typical

H-implantation

the measured film resistance increased from 1.53 Q to 19.30 Q after a 10

_keV/amu

implanta-tion at a dose of

1018

at . cm - 2,

then to 31.5 Q

after a 5

_{keV/amu implantation}

at a dose of 7 x

1017

at. cm -2,

and

_finally

to 38.7 Q after

a 2.5

keV/amu implantation

at a dose of

1017 at . cm - 2

_{( 1 ).}

_(Dose

rates

_ranged

from 8 x

1015 at. cm - 2 . S - 1

to 2 x

1015

at CM-2.S-1.)

The

_{resistivity annealing}

curve obtained on

Al-implanted

Al at a

_relatively

low dose is

presented

in

figure

la and

_compared

to the result

_previously

obtained

by Burger et

al.

_[5]

on neutron-irradiated

bulk Al. It is

_readily

seen that the

_{general shape}

of

the

_annealing

_spectra

are

_quite

similar. The

annealing

peaks

at 19 K

_(usually

ascribed to

_{close-pair annealing)}

and - 230 K

_{(stage III)}

are absent in the

ion-implant-ed

_sample,

while the detailed structure of _stage II

annealing

differs somewhat. The overall

similarity

is

_comforting,

as neutron- and ion- irradiation are

expected

to

_produce

similar

_{damage :}

this indicates that film size effects do not dominate the

_annealing

process, a

_point

that is reinforced

_by

the fact that the

e) These values may be accounted for if the tail of the implan-tation profile extends out to the surface.

FIG. 1. _{- a)} Differential _{resistivity annealing} curve for

Al-implanted Al, at a dose of 3 x 1013 at . cm- 2 _(dose rate of 8 x 1014 at. cm - 2 . S - 1). The film resistivity was ~ 5 ~,~ . cm

before _implantation and 7.5 _{Jl!1. cm} after _{implantation. b)} Diffe-rential resistivity annealing curve for neutron-irradiated bulk Al

according to reference _[5].

same

_annealing

_spectrum

was found after Al-

implan-tation in a 450

A -

thick film. The absence of the

peak

at 230 _{K may}

_yield

some information on thp

concentration of _energy

_{deposition (hence}

of defect

creation)

due to the

_incoming

ion : if the

_damage

are more

_probable

’than _monovacancy

formation,

a _process that would lead to a _stronger

_annealing

in the first

_part

of _stage III

_(if

one assumes that all of

stage

III is due to _vacancy

_annealing).

The dose

dependence

of the relative

_resistivity

increase is shown in

_figure

2 : the incremental

_change

in the

resistivity

shows an inverse-dose

_dependence

over

nearly

three orders of

_magnitude.

FIG. 2. - Dose

dependence of relative _resistivity increment for

Al-implanted Al (implantation energy 100 keV ; film thickness 1300

_A).

The effect of interstitial

hydrogen

is

_strikingly

demonstrated in

_{figure 3a ;}

when

_compared

to

_figure

la

a two-fold increase is found in

_stage

I

annealing

and

the _stage III

_{annealing amplitude}

is

_{correspondingly}

reduced. The reappearance of a

_{large close-pair}

annealing

peak

at 19 K can be accounted for

_by

the

lower

_deposited

_energy concentration

_produced

_by

H-

_{implantation.}

At

_{high, fairly uniform}

concentra-tions,

the

_annealing

_spectrum shifts

_considerably

toward

_{higher energies.}

We have made no

_attempt

to

_interpret

the observed

_peaks,

but it is

_quite

clear that at least some of them

_(see

dotted

_peak

at 200 K

in

_figure

3b and

_peak

at 300 K in

_{figure 3c)}

are far too

sharp

to be accounted for

_by

the

_migration

of a

simple

defect : H-

_{disordering and/or phase}

transformations could

_possibly

occur,

accompanied

or followed

_by

bubble formation as evidenced

_by

optical microscopy

on

_{room-temperature}

annealed

samples.

The

_annealing

_spectrum

of

_high-dose

0-

_implanted

Al

_(Fig.

₄₎

is

_{again quite}

different. The results are too

preliminary

to allow _any

_analysis,

but

_they

do suggest

that

_{resistivity annealing}

_experiments

_may be an

interesting

method for the

_study

of oxide formation after low

_temperature

_{implantation.}

Further work is

obviously

needed to obtain

_quantitative

_information,

but a number of

_interesting

features have

_already

appeared

in these

_{preliminary resistivity annealing}

experiments

on

_{low-temperature implanted}

films.

FIG. 3. - Differential

resistivity annealing curves for H- implanted

AI at : a) low _dose, for which a 15 _{keV/amu implantation}

_produced

the same total resistivity change as Al in _figure I _{a) ; b) high} total dose and _fairly uniform concentration obtained by implanting

at 10, 5 and 2.5 keV/amu; c) same as _b) with concentration

multi-plied by 10. Dose rates _ranged from 8 x IOt5 at.cm-2-s-1 to

2 x 1015 at . cm-2 . s-1. Note : Due to temperature limitations, curve _b) could not be followed above 330 K. However, at that

"

L-308 JOURNAL DE PHYSIQUE - LETTRES

Acknowledgments.

- We wish to

acknowledge

Dr. P. Lucasson for useful discussions and F. Lalu and M. Salome as well as S. Buhler and the

Low-Temperature Group

of Institut de

_Physique

Nucleaire,

Orsay,

for their

_help

in

_designing,

_building

and

operat-ing

the _cryostat.

FIG. 4. - Differential

resistivity annealing curve for 0- _implanted

Al at high, fairly uniform concentration (implantation energies 50 and 25 keV/amu). See note in figure 3. In this case, - 70 % of the

resistivity increase remains at 330 K.

References

[1] Ion Implantation in Metals, ed. S. T. Picraux, E. P. Eer Nisse and F. Vook (Plenum Press, N. _Y.) 1974.

[2] LAMOISE, A. M., CHAUMONT, J., MEUNIER, F. and BERNAS, H.,

to be _published.

[3] LINDHARD, J., SCHARFF, M. and SCHIØTT, H., Mat. _Fys. Medd.

Dan. Vid. Selsk. 33 (1963) 14.

[4] SCHIØTT, H., Mat. Fys. Medd. Dan. Vid. Selsk. 35 (1966) 9.

[5] BURGER, G., ISEBECK, K., VÖLKL, J., SCHILLING, W. and _WENZL,

H., Z. _{Angew. Phys.} 22 (1967) 452.

[6] CORBETT, J. W., SMITH, R. B. and WALKER, R. M., Phys. Rev.