Materials Sciences and Applicatio ns, 2011, 2, 6-13
doi:10.4236/msa.2011.21002 Published Online January 2011 (http://www.SciRP.org/journal/msa)
Forming Stages of Polycrystalline TiN Films
Depending on the Nitrogen Concentration in
Mixed Gas
Anna L. Kameneva
State Educational Institution of the Higher Vocational Education, Perm State Technical University, Perm, Russia
Received October 6th, 2010; revised December 7th, 2010; accepted December 13th, 2010.
ABSTRACT
The influence of nitrogen concentration in mixed gas on temperature conditions, structure and phase composition of the
TiN film deposited by ar c spraying has been investigated. By electron microscopic investigation s and X-ray diffraction
phase analysis was recognized forming stages and structuring process of the film with main cubic phase (111) TiN. It
was discovered that forming stages and process of structuring of ion-plasma TiN films are affected by both film tem-
perature and its rate of heating.
Keywords: Polycrystalline TiN Film, Arc Spraying, Temperature Conditions, Forming Stages, Structure and Phase
Modification
1. Introduction
The stabilization and interpretation of properties of
ion-plasma polycrystalline films is a fairly complicated
problem because of a great variety of factors which in-
fluence their characteristics [1-5]. The solution of this
problem is impossible without studying the laws that
govern the processes of the formation of polycrystalline
films depending on technological parameters, as well as
without studying phase composition, the structural and
morphological features of the relief of the surfaces of the
films and its properties [6-19].
The aim of this work is to examine the influence of ni-
trogen concentration in mixed gas on the temperature
conditions, pattern and formation stages, structure forma-
tion processes, prevailing orientation direction, phase
composition and mechanical properties of TiN films
during electric-arc evaporation.
2. Methods of the Substrates Preparation,
Forming and Investigation of Structure
and Conditions of TiN Film
2.1. Methods of the Preparation of Substrates
and Formation of TiN Film
TiN films were produced using industrial ННВ-6,6-И4
unit by means of one electric-arc evaporator with ВТ1-00
titanium cathode at various nitrogen concentration in
mixed gas. To increase the adhesive strength of TiN film
on the surface of the test samples Ti underlayer was ap-
plied after its ion cleaning-heating.
2.2. The Method of Substrate and TiN Film
Temperature Control
Temperature of test pieces surface as well as the film
temperature after each 10 minutes of the film deposition
have been measured by infrared contactless pyrometer
after both ionic cleaning and sublayer applying, a whole
duration of the precipitation process was 30 minutes.
2.3. Methods of Studying the Structure, Phase
Composition and Conditions of TiN Film
Morphological traits of the formed films have been in-
vestigated by bitmapped electron microscope BS 300
with prefix for microanalysis EDAX Genesis 2000.
X-ray diffraction phase analysis of TiN film was carried
out using X-ray diffractometer DRON-4 in Cu Kα radia-
tion. Microhardness of the composition has been meas-
ured by microhardness tester PМТ-3 with indenter load
of 0.5 N after the film precipitation process.
3. Simulation Results and Discussion
The process conditions of the substrate preparing carried

Forming Stages of Polycrystalline TiN Films Depending on the Nitrogen Concentration in Mixed Gas7
out before the film deposition-ionic-bombardment clean-
ing and sublayer Ti applying—are given in Table 1, and
Table 2 lists the process conditions for the arc spraying,
and microhardness of composition TiN film- substrate
(hereinafter named as composition microhardness).
3.1. Results of the X-Ray Diffractometer Phase
Analysis of the TiN Polycrystalline Film
Results of X-ray diffractometer phase analysis of the TiN
films deposited by arc spraying with 50% nitrogen con-
centration and higher are given in Figure 1, Table 3 and
Table 4. The TiN film consisting of main cubic phase
with (111) direction of preferred lattice orientation and
auxiliary hexagonal phase of TiN0.3 is forming on the
substrate independently on nitrogen concentration.
The TiN film with maximum microhardness produced
at optimal temperature and process parameters of spray-
ing (film heating rate of 14.2 K/min and nitrogen con-
centration in gas mix of 90%) has the following structure
characteristics: maximum volume fraction of the cubic
phase TiN (111) equal to 99.2%, and minimum the one
of hexagonal phase TiN0.3 (101) equal to 0.8%; minimum
deviation of cleavage spacing from table value; maxi-
mum peak width of the TiN (111) phase, and minimum
the one of TiN0.3 (101) regardless of heterogeneous in-
side stresses in the film appearing as a result of various
direction of peak coordinate departures of TiN (111) to
less angles and the one of TiN0.3 (101) to most angles.
For the first time it was discovered that decreasing of
nitrogen concentration less than 70% leads to increasing
of hexagonal phase TiN0.3 volume fraction in the film:
equal parts of argon and nitrogen result in forming dis-
ordered two-phase film with maximum deviation of the
cleavage spacing from table value and with less value of
composition microhardness.
Table 1. Process conditions of the ionic-bombardment cleaning and sublayer Ti applying.
Process U, V
Substrate—plazma
source distance, mm T, minP, PaIfocusing coil, AIstabilizing coil, AIarc, AV, rpm Gas Final substrate temperature, K
Ionic cleaning high600 270 5 0.011.50 2.50 80 2.5 Ar 651
Sublayer applying bias200 270 3 1.0 1.50 2.50 80 2.5 Ar
Table 2. Process conditions of the TiN film applying by arc spraying.
Tfilm, K
Process durability, min Experiment No. N2 concentration, % L, mm P, Pa Iarc, AUbias, V
10 20 30
Vfilm heat, K/min Hμ, GPa
1 50 625 640 670 12.3 16.0
2 70 625 650 680 12.5 21.0
2 90
270 1.0 80 200
645 670 725 14.5 27.1
Table 3. Phase composition and structural characteristics of the TiN films produced by arc spraying: V is phase inclusion
volume fraction, dTiN/dTiNtable is cleavage spacing, ITiN/ITiN0,3 is intensity ratio of all reflexes of cubic TiN phase and hexago-
nal TiN0,3 the one, maxI111TiN/IΣ and maxI101TiN0,3/IΣ are ratios of maximum reflex intensities (111) or (101) to total intensity of
all TiN phase reflexes, and β0 is breadth of X-ray diffraction line.
V, %
Experiment
No.
N2
concentration, % TiN TiN0,3
dTiN
dTiNtable, nm
dTiN0,3
dTiN0,3table, nm
ITiN
ITiN0,3
IΣ
maxI111T
iN
IΣ
maxI 101TiN0,3
IΣ
maxITiN
maxITiN0,3
β0111
β0101
1 50 85.514.5
0.2458
0.2450
0.2257
0.2268 1.87 255 0.650.35 1.59 1.70 0.67
2 70 98.91.1
0.2465
0.2450
0.2262
0.2268 19.10100.50.810.01 54.0
2.5
0.57
3 90 99.20.8
0.2465
0.2450
0.2265
0.2268 20.20106.00.760.02 32.4
3.3
0.55
Table 4. Positions of the diffraction peaks.
2θ, grad
Nitrogen concentration, %
Film Phase Lattice type Grain orientation2θтабл, grad
50 70 90
TiN Volume-centred cubic <111> 36.8048 36.55 36.45 36.45
TiN
TiN0,3 Hexagonal <101> 39.7086 39.95 39.85 39.80

Forming Stages of Polycrystalline TiN Films Depending on the Nitrogen Concentration in Mixed Gas 8
50% N2
(a) (b)
Figure 1. (a) Comparative band of diffractogram fragments for TiN film pieces produced by arc spraying at various nitrogen
concentrations in mixed gas. (b) Comparative diagram of diffraction peaks of the cubic phase TiN reduced to 100% of
maximum peak over the range 25…80˚.
3.2. Results of the Electron Microscopic
Investigations of the Polycrystalline TiN
Film
Surface morphologies of all produced TiN films have
been investigated in order to find a reason of the change
of mechanical properties.
Based on morphological investigation at low magnifi-
cation it was discovered that TiN films formed by arc
spraying at various nitrogen concentrations have various
roughness (Figure 2). Based on investigations of film
surface morphology, it was deduced that TiN film form-
ing stages are identical in case of main cubic phase in
spite of various volume part ration of phases in the film:
• Globular stage, when there is no directivity of
border regions in space. Spherical globules are forming
with minimum substrate contact surface (Figure 3(a)) in
conditions of low temperatures up to 625 K and low
substrate wetting. Notwithstanding that decrease of argon
concentration in gas mix reduces both ion density and ion
mobility, increase in nitrogen concentration boosts film
heating rate and initiates van der Waals forces to appear
which facilitate the substrate wetting and forming of
applanate globular structures with contacting area equal
to globule diameter (Figures 3(b,c)). Globules having
minimum height and diameter are forming at nitrogen
concentration of 90% in gas mix.
• Stage of transit of the globular structure to grain
substructure. 3D formations are forming on the film
surface in direction perpendicular to substrate surface
(Figure 4). Increasing of film temperature due to its
heating rate increase, and increasing of rate of plasma
chemical reaction due to nitrogen concentration increase
both together facilitate to a grain substructure ordering
(Figure 4(c)). The 3D formations with ordered grain
substructure correspond to films formed at nitrogen
concentration of 90% (Figure 4(c)).
• Stage of integration of the 3D formations having
grain substructure. Increasing of film forming durability
leads to integration of the formations having grain sub-
structure into microsystems of various configurations:
single 3D formations and applanate islands with grain
substructure (Figure 5(a)) at minimum film heating rate
Vheat = 12.3 K/min, integration of the 3D formations
having grain substructure and initially ordering of their
surfaces (Figure 5(b)) at Vheat = 12.5 K/min and maxi-
mum nitrogen concentration of 90%, integration of the
3D formations having grain substructure to islands with
pseudoplains {100} on their surface (Figure 5(c)) at Vheat
up to 14.2 K/min and film temperature up to 725 K.
• Stage of nucleation of polycrystalline constituent of
the film with main cubic (111) TiN phase (Figure 6). It
carries in temperature rating of 650 to 670 K at film
heating rate of 12.5 to 14.2 K/min. Maximum tempera-
ture and film heating rate both facilitate to multiple in-
creasing of seeds number and reducing of crystal grain
diameter. Polycrystalline structures in form of seed crys-
tallites with pseudoplains {100}, unidirectional to sub-
strate and equispaced on its surface, germ in process of
film deposition at nitrogen concentration of 90% in
mixed gas (Figure 6(c)).
• Stage of island forming of the polycrystalline film.
Stage of nucleation of polycrystalline constituent of film
only in conditions of further temperature increasing to

Forming Stages of Polycrystalline TiN Films Depending on the Nitrogen Concentration in Mixed Gas 9
(a) (b) (c)
Figure 2. Photomicrographs of TiN films formed by arc spraying at various nitrogen concentration in mixed gas: (a) 50%; (b)
70%; (c) 90%.
200HM 200HM 200HM
(a) (b) (c)
Figure 3. Photomicrographs of the TiN film on globular stage: (a) Ø 1.0 μm at 50%; (b) Ø 1.3 μm at 70%; (c) Ø 1.2 μm at
90%.
200HM
2
00
HM
200HM
(a) (b) (c)
Figure 4. Photomicrographs of the TiN film on the stage of forming of 3D formations with grain substructure: (a) Ø 3.0 μm at
50%; (b) Ø 3.0 μm at 70%; (c) Ø 720 nm to 2.5 μm at 90%.
200HM 200HM 200HM
(a) (b) (c)
Figure 5. Photomicrographs of the TiN films on stage of integration of 3D formations having grain substructure into
microsystems: (a) 3D formations Ø 3.3 μm at 50% of nitrogen; (b) Integrations with dimension L = 2.5 μm consisting of
globules Ø 1.0 μm and Ø 1.5 μm at 70%; (c) Integrations with dimension L = 5.0 μm consisting of 3D formations with
diameter of Ø 3.0 μm and Ø 2.0 μm at 90%.

Forming Stages of Polycrystalline TiN Films Depending on the Nitrogen Concentration in Mixed Gas 10
200HM
200HM 200HM
(a) (b) (c)
Figure 6. Photomicrographs of the TiN film on stage of nucleation in form of: (a) Initial polycrystalline formations in form of
frustums with bases of 1.4 × 4.0 μm at 50% of nitrogen; (b) Seed crystallite in form of frustums with bases of 0.4 × 0.9 μm and
1.3 μm at 70%; (c) Seed crystallite, Ø 1.2 μm, with pseudoplains {100} at 90%.
670... 725 K with heating rate not less than 12.3 K/min
goes to stage of forming of 2D polycrystalline formations
in form of islands on surface of the film (Figures 7(a-f)).
Film temperature increase related to increasing of
nitrogen concentration and film deposition duration leads
at once to increasing of 2D island diameter and
decreasing of both island height and seed crystallite
diameter. Maximum increasing of the film temperature
and its heating rate up to optimal values of 725 K and
14.2 K/min respectively (90% of nitrogen) facilitates to
multiple increasing of islands number. It will be observed
a repetitive forming of 3D formations with grain
substructure on surface of polycrystalline islands only at
50% and 70% nitrogen concentration (Figures 7(b,c)).
• Stage of continuous film forming. An electron micr-
oscope investigation of the film surface morphology has
shown that continuous film formed at surface heating up
to 680 K has the cellular structure (Figures 8(a,c)), and at
surface heating up to 725 K it has nanodispersed grain the
one (Figures 8(e,f)) due to film structure stabilization.
(a) (b) (c)
2MKM 2 MKM
2MKM
2 MKM
1 MKM
(d) (e)
Figure 7. Photomicrographs of the TiN film in stage of forming of polycrystalline 2D islands with following dimensions: (a) Ø
10.0 μm and height H = 1.5 μm at 50% of nitrogen; (b) Max Ø 16.5 μm and H = 1.0 μm, min Ø 2.5 μm and H = 0.3 μm, limit
distance between islands for their integration is 700 nm (forced fragment right), all at 70%; (c) Ø 4.0 μm and H = 1.0 μm;
and (d) Ø 9.0 μm and H = 1.0 μm, both latter at 90% of nitrogen.

Forming Stages of Polycrystalline TiN Films Depending on the Nitrogen Concentration in Mixed Gas11
2 MKM
2 MKM
200 HM 2 MKM
(a) (b) (c) (d)
2 MKM 200 HM200 HM
(e) (f) (g)
Figure 8. Photomicrographs of TiN film on stage of continuous film forming: with cellular structure (a) Cell Ø 900 nm to 3.0
μm at 50% of nitrogen, and (c) Cells Ø 700 nm to 2.0 μm at 70%; with grain substructure (e), (f) Light grains of 30 nm, dark
grains of 50 nm, both at 90% of nitrogen. Film material “lack”: (b) 2.5 μm at 50%; (c) 8.5 μm × 15.0 μm, (d) 3.5 μm, both at
70%; (g) 90%, 3.4 μm, forced fragment to the right shows that minimum size of crystallite does not exceed 20 nm.
The material “lack” of the ionic plasma film increases
along with increasing of the nitrogen concentration in the
mixed gas (Figures 8(b-d, g)). Minimum size of the film
uniformity, nano-crystalline structure of a chip, mini-
mum size of seed crystallite, fine grain substructure of
the film are indicative for the following forming condi-
tions: 90% of nitrogen, T = 645...725 K, Vfilm heat = 14.2
K/min (Figures 8(e-g)).
Stage of forming of ordered 2D and 3D formations on
the continuous film surface. Independently on techno-
logical and temperature conditions of the film forming,
microscopic formations are forming on film’s surface
after 30 minutes as a result of integration of 2D and 3D
formations (Figure 9). At 70% nitrogen concentration,
solitary 3D formations with ordered grain substructure
appear on the continuous film surface (Figure 9(a))
which worsen film surface quality (were not observed in
earlier experiments). At maximum nitrogen concentra-
tion of 90% we can observe on film surface 2D rod-
shaped formations having ordered column substructure
(Figure 9(b)).
4. Summary
A phase-structural condition of the TiN films formed by
arc spraying at various nitrogen concentrations has been
investigated by method of X-ray diffraction phase analy-
sis. It was first established that decreasing of the nitrogen
concentration less than 70% leads to increasing of vol-
200 HM
(a)
2 MKM
(b)
Figure 9. Photomicrographs of the TiN on stage of the con-
tinuous film forming with surface structures in form of: (a)
3D formations sized as 3.0 × 4.2 × 1.2 μm at 70%, and (b)
2D rod-shaped formations with length of 20 μm and width
of 3 μm at 90%.

Forming Stages of Polycrystalline TiN Films Depending on the Nitrogen Concentration in Mixed Gas 12
Globular stage:
forming of globules
without substrate
surface wetting
(50%) and with the
one (70%, 90%)
Forming of 3D
formations with
grain
substructure:
non-ordered at
50%, 70%;
ordered at 90%
Integration of the 3D
formations with grain
substructure: without
ordering at 50%; initial
ordering at 70%; forming
of pseudoplains {100} on
surface at 90%
Germi-nati
on of
polycrysta
lline
constituent
of the film
Forming
of
polycrysta
lline 2D
island s
Forming
of
continuou
s
polycrysta
lline film
Forming of 3D
ordered grain (70%)
and 2D ordered
column (90%)
formations on the
continuous film
Figure 10. Stages of the TiN film forming depending on nitrogen concentration in mixed gas, film temperature, and film
heating rate. Forming of films with main cubic TiN phase by arc spraying method (50% of N2, 625 to 670 K, Vfilm heating = 12.3
K/min; 70% of N2, 625 to 680 K, Vfilm heating = 12.5 K/min; 90% of N2, 645 to 725 K, Vfilm heating = 14.2 K/min).
ume fraction of the hexagonal TiN0.3 phase and to wors-
ening of its mechanical properties.
Structuring of the films with main cubic (111) TiN
phase goes through the following stages: globular, form-
ing of 3D formations with grain substructure, integration
of the 3D formations, nucleation of polycrystalline con-
stituent of the film, forming of polycrystalline 2D islands,
forming of continuous film, forming of ordered 3D and
2D formations on the continuous film surface (Figure 10).
In summary, it was discovered that except of film
temperature film heating rate first of all effect on origin,
forming stages, and structuring of the ion-plasma TiN
films in process of the film applying.
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