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Interface reaction of Si thin film on Au substrate
Applied Surface Science 47 (1991) 365 369 North-Holland
365
Interface reaction of Si thin film on Au substrate K. Nishimori, H. T o k u t a k a , H. Sumi 1 a n d N. l s h i h a r a Department of Electrical and Electronic Engineering. Tottori Unmersity, Kovama Tottori 680. Japan Received 26 September 1990; accepted for publication 31 December 1990
We have investigated the Si-Au interface reaction introduced by Si deposition on a Au polycrystalline substrate using Auger electron spectroscopy and scanning electron microscopy (SEM). Initial growth of the Au-rich silicide was demonstrated in detail using difference spectra of the SiLVV Auger lines at successive stages of Si deposition. This revealed that the Si-Au intermixing reaction starts at the very beginning of Si deposition on Au substrates at room temperature. The Au-rich silicide formed in the early stage (up to - 10 A) of Si deposition stably existed after annealing at 350 ° C. The stable Au-rich silicide was also formed due to the strong intermixing at 350 ° C annealing of an - 100 * Si film on Au. SEM observations showed that the population of pits, where Si reacts with Au on the Au grains, increased with increasing Si film thickness after the annealing.
1. Introduction Metal/Si interfaces are widely investigated to control the electronic characteristics of integrated circuit devices and to increase the reliability of the device structures. Many studies of the interfaces have been made by metal deposition onto Si substrates [1-3], In the case of Au deposited on Si at room temperature (RT), different results [4-7] have been obtained. The most controversial point among them is the existence of a critical thickness for the onset of the intermixing reaction. In order to study the silicide reaction at the interface in detail, a reverse approach, which employs deposition of Si on a metal substrate [8], is useful, as well as the above method. The initial stages of the interracial reactions for Au on Si systems would be different from that for Si on Au systems. However, Franciosi et al. reported that the formation of an S i - A u alloyed interface region is a common feature of both interface formation processes [9]. It is more meaningful to compare the results for Si on Au systems with those for Au on Si systems. In this paper, we have demon-
Present address: Sony Corporation. Atsugi, Kanagawa 243, Japan.
strated the advantages of the method for the initial growth of a Si film on a polycrystalline Au substrate, using Auger electron spectroscopy (AES). The surface topographs and Au silicide reactions of a Si film with the substrate annealed at 350 ° C have been observed by a scanning electron microscope (SEM) and AES as a function of the film thickness.
2. Experimental Au substrates were prepared on Mo (99,9 wt%) thin foils (size: 15 × 25 × 0.1 mm 3) by deposition of 2000-3000 A from a Au (99.9 wt%) evaporation source. Si deposition was made by resistive heating of the Si wafer through which an electric current directly passed. The in-situ calibration of the Si deposition rate was carried out with a quartz oscillator [10] and with Si and Au Auger signal intensities. The rate was 0.04 A / s . Auger spectra were taken from the specimen at successive stages of Si deposition at RT. Auger measurements were performed with the incident beam current ip = 10 /,tA, the beam energy E p = 2.5 k e V and the modulation voltage for d N ( E ) / d E Auger signal detection Vm = 1.7 Vp_p. For the annealing
0169-4332/91/$03.50 :~:' 1991 - Elsevier Science Publishers B.V. (North-Holland)
366
K. Nishimori et al. / Interface reaction o f Si thin f i l m on A u
experiments, Si films of 4. 80 and 160 A were prepared on Au substrates at RT in the ultra-high vacuum (UHV) chamber. The films were heattreated in UHV at 300 and 3 5 0 ° C for 2 min. Silicide reactions after the annealing were examined by AES. The reacted surface topography was also observed by SEM. Especially, to investigate in detail the change of Si LVV Auger peak shapes due to the silicide reaction, the Auger signals from the lock-in amplifier were stored in the data acquisition system with a personal computer. The signals were numerically averaged in every energy width of 0.7 eV to reduce the noise. The differences between spectra were obtained numerically with the computer.
fig. 1 as a function of Si deposition time. The plots of the Au(239 eV) and A u N V V Auger signals overlap each other. When the Si film uniformly covers the substrate, the Au(69 eV) signal should decrease faster than the Au(239 eV) because of the difference in escape depths [11]. However, in this case such a phenomenon was not seen. This suggests that the uniform overlayer of Si did not form on the surface because of the intermixing between Si and Au. As the Si film thickness increased, the Si LVV peak intensity increased and the Au(69 eV) peak intensity decreased (fig. 1). The shape of the Si LVV spectrum also changed remarkably (fig. 2A). Each SiLVV spectrum in fig. 2A was obtained at the deposition time labeled in fig. 1. This spectrum change can be divided into three regions of the insets (i), (ii) and (iii) in fig. 1. The regions (i), (ii) and (iii) correspond to a Si film thickness from 0 to 11 A, from 11 to 40 A and more than 40 A, respectively. The intensity of the Si LVV peak in region (iii) was measured as the parameter H indicated in the inset spectrum in fig. 1. When the SiLVV spectrum showed a doublet peak shape at electron energies of 90 and 95 eV in regions (i) and (ii), the peak intensity was measured for the higher energy peak of 95 eV in the same manner as above. The
3. Results and discussion
It has been reported that, when a Au thin film of several 100 A on a Si substrate is annealed at a temperature from 100 to 200°C, Si atoms from the substrate appear on the Au film and form Au-rich silicide compounds [1,2]. The initial growth of Si film on Au at RT was measured with AES. The normalized intensities of the SiLVV and A u N W (69 eV) Auger lines are plotted in
Si/Au
o Si(92eV) (iii)
<
Si LVV peak (ii)
' _L
o
e-
]', Au(69eV), (239eV)
w I-
.~.c
ft.)
+
zx•
o
<
&&&
A
~.
,a
-5 E
e~ ~ O
¢d t+ +'+o ° ° ° e f QO
z
i A
~Q5 o
o
G
o f
+
o o
z~
g
z~
tco
560
1~o 1500 ' Deposition time(sec.)
200O '
Fig. 1. Auger intensities as a function of Si deposition time. The inset Auger spectra of (i), (ii) and (iii) are typical Si LVV d N / d E peaks in their regions. Solid circles, hatched circles and open circles belong to the spectra of regions (i), (ii) and (iii). respectively.
K. Nishimori et al. / Interface reaction of Si thin film on A u
Si doublet peak structure appeared at the beginning of the deposition stage (i). This shows the strong intermixing and chemical reaction between Si atoms and Au substrate at RT in this region. This reaction produced a Au-rich silicide at the surface. In region (iii) of Si deposition, more than 40 A (label h), a weak intermixing and alloyed A u - S i layers can be seen to grow with increasing Si film thickness. However, the spectra of Si LVV Auger peaks in the middle region of (ii) are complicated. To see the interface reaction in more detail, we made the difference spectra of fig. 2B from the spectra of fig. 2A. That is, the difference spectra (b - a) of fig. 2B was obtained by numerical subtraction of spectrum a from spectrum b of fig. 2A with a personal computer. These difference spectra indicate the following results. First, in the early stage of Si deposition from 0 to 1.5 ,~, since the spectrum (b - a) indicated a feature similar to the doublet peak shape of spectrum b, an initial Au-rich silicide was found at the surface. Second, in the deposition range from 1.5 to 4.5 A Si, the
a
367
spectrum (c - b) pointed out that only the higher energy peak at 95 eV grew in the doublet peak of the Si LVV spectrum b of fig. 2A. This growth of the 95 eV peak corresponds to the energy shift of the Au 5d antibonding peak in the photoemission spectra due to the strong chemisorption of Si on Au [9]. Third, in the Si deposition region from 5.0 to 11 ,~, since the difference spectrum (e - d) had a doublet peak feature similar to that of spectrum ( b - a), the growth of a stable Au-rich silicide developed over the substrate. The Au-rich silicide had the composition of Au3Si from the ratio between the Au and Si Auger signal intensities at the deposition time of label e in fig. 1. Fourth, for Si deposition of more than 11 A, we were able to see the growth of the single peak at 93 eV only, which corresponded to the pure Si peak, as shown in the difference spectra (f - e) to (j - i) of fig. 2B. From the results of regions (ii) and (iii) in fig. 1, the deposited Si atoms are considered to have a very weak reaction with Au atoms from the substrate. Furthermore, Si deposition was carried out up to
Si on A u
b C
d e
f g
E
~
tX-a
~
c-b
~
d-c
~
e-d
~
f-e
h
W
ILl v Z
8'0
8'5
9'0
Electron
9's
,;o
energy(eV)
I
165 .o
80
85 90 95 100 Electron energy(eV)
105
110
Fig. 2. (A) Si LVV Auger spectra at successive stages of Si deposition. Spectra a to j were obtained at the deposition times labeled a to j in fig. 1, respectively. (B) The difference spectra between the spectra in (A). For example, (b - a) was obtained by subtraction of spectrum a from spectrum b in (A).
368
K. NLThimori et al, / Inte([ace r e a c m m of Si thin f i l m on ,4 u
(a) 4/~ Si
on Au
/------ (2)
~Anneat.
/j
(b) 80.A Si
/-Illl
J
(c) 160.&Si
on Au
IIU / ~/
(2)
on Au
I
Si_LVVl/
Au - NVV
Fig. 3. AuNVV and Si LVV Auger spectra taken from the Si on Au system of (a) 4 A, (b) 80 A and (c) 160 A Si fihns at successive stages of (1) as deposited, (2) 300 o C and (3) 350 ° C annealings for 2 rain.
about 200 A where the Si signal of fig. 1 showed that of the bulk Si. Next, in order to compare the silicide reaction at RT with that at higher temperature, we tried heat-treatments of the Si film on the Au substrate as a function of film thickness. Si films of (a) 4 A. (b) 80 )~, and (c) 160 A, were deposited on Au substrates at RT. The films were annealed at
3 0 0 ° C for 2 rain, then at 3 5 0 ° C for 2 min in the UHV chamber. Auger measurements of the films were made after each annealing. The Si EVV and A u N V V Auger spectra are shown in fig. 3. In (a) the 4 A Si film, the doublet peak features of the Si Auger spectra remained the same even after the annealings. In both (b) 80 A and (c) 160 A, the single Si peaks were transformed to the doublet
Fig. 4. SEM images for (a) 4 A, (b) 80 ,~ and (c) 160 .-~ Si films on Au substrates after the 3 5 0 ° C anneal of fig. 3. Markers represent 3.0 p.m.
K. Nishimori et al. / Interface reaction of Si thin film on Au
peak similar to that of spectrum e in fig. 2A after the annealings, as shown in spectra (b-3) and (c-3) of fig. 3. Therefore, for these Si film thicknesses, we can see the stable Au-rich silicide after annealing at 350 o C. The doublet peak features changed into the single peak after annealing at 420 ° C and then disappeared at more than 5 0 0 ° C for every film thickness. To observe the surface topography of the specimens after the annealing at 350 ° C in fig. 3, they were exposed to air during the transfer into the SEM apparatus. The observed SEM images are shown in fig. 4. The image of 4 A indicated a lot of black patches like amoebas. These patches were the ~pits formed on the grains of Au. In the case of 80 A Si film, the number of pits further increased due to the progressive reaction of Si with Au. When the Si film thickness was 160 A, the pits became the densest among the three pictures. It was reported that, in the Au deposition on Si(111), the pits appeared on the agglomerated Au islands by annealing at about 4 0 0 ° C [12]. The other specimens of 4, 80 and 160 ,~ Si films on Au without annealings were observed by SEM. Each SEM image showed that no pits appeared on the flat grains of Au. From the results of figs. 3 and 4, the black pits of SEM images can be considered to indicate the formation of stable Au-rich silicides by annealing at 350 ° C.
4. Conclusion We have studied the surface and interfacial reactions of Si film on Au substrate, using AES
369
and SEM. The AES measurement showed that S i - A u intermixing reaction takes place at the very beginning of Si deposition on Au at RT. The initial growth of Au-rich silicides was also observed in detail by using the difference spectrum technique. The SEM observation indicated numerous pits which were produced by the reaction of Si and Au after annealing at 350 o C.
Acknowledgement A part of this work was supported by Saneyoshi scholarship foundation.
References [1] A.K. Green and E. Bauer, J. Appl. Phys. 47 (1976) 284. [2] A. Hiraki, Surf. Sci. Rept. 3 (1984) 357. [3] G. Le Lay, M. Manneville and R. Kern, Surf. Sci. 65 (1977) 261. [4] A. Taleb-Ibrahimi, C.A. S6benne, D. Bolmont and P. Chen, Surf. Sci. 146 (1984) 229. [5] M. Hanbficken, Z. Imam, J.J. Mdtois and G. Le Lay, Surf. Sci. 162 (1985) 628. [6] H. Dallaporta and A. Cros, Surf. Sci. 178 (1986) 64. [7] K. Hricovini, J.E. Bonnet, B. Carriere, J.P. Deville, M. Hanbticken and G. Le Lay, Surf. Sci. 211/212 (1989) 630. [8] V.M. Bermudez, Surf. Sci. Lett. 230 (1990) L155. [9] A. Franciosi, D.W. Niles, G.M. Margaritondo, C. Quaresima, M. Capozi and P. Perfetti, Phys. Rev. B 32 (1985) 6917. [10] K. Nishimori, H. Tokutaka and K. Takashima, Surf. Sci. 100 (1980) 665. [11] P.W. Palmberg and T.N. Rhodin, J. Appl. Phys. 39 (1968) 2425. [12] T. Ichinokawa, Y. Ishikawa, M. Kenmochi, N. Ikeda, Y. Hosokawa and J. Kirschner, Surf. Sci. 176 (1986) 397.
365
Interface reaction of Si thin film on Au substrate K. Nishimori, H. T o k u t a k a , H. Sumi 1 a n d N. l s h i h a r a Department of Electrical and Electronic Engineering. Tottori Unmersity, Kovama Tottori 680. Japan Received 26 September 1990; accepted for publication 31 December 1990
We have investigated the Si-Au interface reaction introduced by Si deposition on a Au polycrystalline substrate using Auger electron spectroscopy and scanning electron microscopy (SEM). Initial growth of the Au-rich silicide was demonstrated in detail using difference spectra of the SiLVV Auger lines at successive stages of Si deposition. This revealed that the Si-Au intermixing reaction starts at the very beginning of Si deposition on Au substrates at room temperature. The Au-rich silicide formed in the early stage (up to - 10 A) of Si deposition stably existed after annealing at 350 ° C. The stable Au-rich silicide was also formed due to the strong intermixing at 350 ° C annealing of an - 100 * Si film on Au. SEM observations showed that the population of pits, where Si reacts with Au on the Au grains, increased with increasing Si film thickness after the annealing.
1. Introduction Metal/Si interfaces are widely investigated to control the electronic characteristics of integrated circuit devices and to increase the reliability of the device structures. Many studies of the interfaces have been made by metal deposition onto Si substrates [1-3], In the case of Au deposited on Si at room temperature (RT), different results [4-7] have been obtained. The most controversial point among them is the existence of a critical thickness for the onset of the intermixing reaction. In order to study the silicide reaction at the interface in detail, a reverse approach, which employs deposition of Si on a metal substrate [8], is useful, as well as the above method. The initial stages of the interracial reactions for Au on Si systems would be different from that for Si on Au systems. However, Franciosi et al. reported that the formation of an S i - A u alloyed interface region is a common feature of both interface formation processes [9]. It is more meaningful to compare the results for Si on Au systems with those for Au on Si systems. In this paper, we have demon-
Present address: Sony Corporation. Atsugi, Kanagawa 243, Japan.
strated the advantages of the method for the initial growth of a Si film on a polycrystalline Au substrate, using Auger electron spectroscopy (AES). The surface topographs and Au silicide reactions of a Si film with the substrate annealed at 350 ° C have been observed by a scanning electron microscope (SEM) and AES as a function of the film thickness.
2. Experimental Au substrates were prepared on Mo (99,9 wt%) thin foils (size: 15 × 25 × 0.1 mm 3) by deposition of 2000-3000 A from a Au (99.9 wt%) evaporation source. Si deposition was made by resistive heating of the Si wafer through which an electric current directly passed. The in-situ calibration of the Si deposition rate was carried out with a quartz oscillator [10] and with Si and Au Auger signal intensities. The rate was 0.04 A / s . Auger spectra were taken from the specimen at successive stages of Si deposition at RT. Auger measurements were performed with the incident beam current ip = 10 /,tA, the beam energy E p = 2.5 k e V and the modulation voltage for d N ( E ) / d E Auger signal detection Vm = 1.7 Vp_p. For the annealing
0169-4332/91/$03.50 :~:' 1991 - Elsevier Science Publishers B.V. (North-Holland)
366
K. Nishimori et al. / Interface reaction o f Si thin f i l m on A u
experiments, Si films of 4. 80 and 160 A were prepared on Au substrates at RT in the ultra-high vacuum (UHV) chamber. The films were heattreated in UHV at 300 and 3 5 0 ° C for 2 min. Silicide reactions after the annealing were examined by AES. The reacted surface topography was also observed by SEM. Especially, to investigate in detail the change of Si LVV Auger peak shapes due to the silicide reaction, the Auger signals from the lock-in amplifier were stored in the data acquisition system with a personal computer. The signals were numerically averaged in every energy width of 0.7 eV to reduce the noise. The differences between spectra were obtained numerically with the computer.
fig. 1 as a function of Si deposition time. The plots of the Au(239 eV) and A u N V V Auger signals overlap each other. When the Si film uniformly covers the substrate, the Au(69 eV) signal should decrease faster than the Au(239 eV) because of the difference in escape depths [11]. However, in this case such a phenomenon was not seen. This suggests that the uniform overlayer of Si did not form on the surface because of the intermixing between Si and Au. As the Si film thickness increased, the Si LVV peak intensity increased and the Au(69 eV) peak intensity decreased (fig. 1). The shape of the Si LVV spectrum also changed remarkably (fig. 2A). Each SiLVV spectrum in fig. 2A was obtained at the deposition time labeled in fig. 1. This spectrum change can be divided into three regions of the insets (i), (ii) and (iii) in fig. 1. The regions (i), (ii) and (iii) correspond to a Si film thickness from 0 to 11 A, from 11 to 40 A and more than 40 A, respectively. The intensity of the Si LVV peak in region (iii) was measured as the parameter H indicated in the inset spectrum in fig. 1. When the SiLVV spectrum showed a doublet peak shape at electron energies of 90 and 95 eV in regions (i) and (ii), the peak intensity was measured for the higher energy peak of 95 eV in the same manner as above. The
3. Results and discussion
It has been reported that, when a Au thin film of several 100 A on a Si substrate is annealed at a temperature from 100 to 200°C, Si atoms from the substrate appear on the Au film and form Au-rich silicide compounds [1,2]. The initial growth of Si film on Au at RT was measured with AES. The normalized intensities of the SiLVV and A u N W (69 eV) Auger lines are plotted in
Si/Au
o Si(92eV) (iii)
<
Si LVV peak (ii)
' _L
o
e-
]', Au(69eV), (239eV)
w I-
.~.c
ft.)
+
zx•
o
<
&&&
A
~.
,a
-5 E
e~ ~ O
¢d t+ +'+o ° ° ° e f QO
z
i A
~Q5 o
o
G
o f
+
o o
z~
g
z~
tco
560
1~o 1500 ' Deposition time(sec.)
200O '
Fig. 1. Auger intensities as a function of Si deposition time. The inset Auger spectra of (i), (ii) and (iii) are typical Si LVV d N / d E peaks in their regions. Solid circles, hatched circles and open circles belong to the spectra of regions (i), (ii) and (iii). respectively.
K. Nishimori et al. / Interface reaction of Si thin film on A u
Si doublet peak structure appeared at the beginning of the deposition stage (i). This shows the strong intermixing and chemical reaction between Si atoms and Au substrate at RT in this region. This reaction produced a Au-rich silicide at the surface. In region (iii) of Si deposition, more than 40 A (label h), a weak intermixing and alloyed A u - S i layers can be seen to grow with increasing Si film thickness. However, the spectra of Si LVV Auger peaks in the middle region of (ii) are complicated. To see the interface reaction in more detail, we made the difference spectra of fig. 2B from the spectra of fig. 2A. That is, the difference spectra (b - a) of fig. 2B was obtained by numerical subtraction of spectrum a from spectrum b of fig. 2A with a personal computer. These difference spectra indicate the following results. First, in the early stage of Si deposition from 0 to 1.5 ,~, since the spectrum (b - a) indicated a feature similar to the doublet peak shape of spectrum b, an initial Au-rich silicide was found at the surface. Second, in the deposition range from 1.5 to 4.5 A Si, the
a
367
spectrum (c - b) pointed out that only the higher energy peak at 95 eV grew in the doublet peak of the Si LVV spectrum b of fig. 2A. This growth of the 95 eV peak corresponds to the energy shift of the Au 5d antibonding peak in the photoemission spectra due to the strong chemisorption of Si on Au [9]. Third, in the Si deposition region from 5.0 to 11 ,~, since the difference spectrum (e - d) had a doublet peak feature similar to that of spectrum ( b - a), the growth of a stable Au-rich silicide developed over the substrate. The Au-rich silicide had the composition of Au3Si from the ratio between the Au and Si Auger signal intensities at the deposition time of label e in fig. 1. Fourth, for Si deposition of more than 11 A, we were able to see the growth of the single peak at 93 eV only, which corresponded to the pure Si peak, as shown in the difference spectra (f - e) to (j - i) of fig. 2B. From the results of regions (ii) and (iii) in fig. 1, the deposited Si atoms are considered to have a very weak reaction with Au atoms from the substrate. Furthermore, Si deposition was carried out up to
Si on A u
b C
d e
f g
E
~
tX-a
~
c-b
~
d-c
~
e-d
~
f-e
h
W
ILl v Z
8'0
8'5
9'0
Electron
9's
,;o
energy(eV)
I
165 .o
80
85 90 95 100 Electron energy(eV)
105
110
Fig. 2. (A) Si LVV Auger spectra at successive stages of Si deposition. Spectra a to j were obtained at the deposition times labeled a to j in fig. 1, respectively. (B) The difference spectra between the spectra in (A). For example, (b - a) was obtained by subtraction of spectrum a from spectrum b in (A).
368
K. NLThimori et al, / Inte([ace r e a c m m of Si thin f i l m on ,4 u
(a) 4/~ Si
on Au
/------ (2)
~Anneat.
/j
(b) 80.A Si
/-Illl
J
(c) 160.&Si
on Au
IIU / ~/
(2)
on Au
I
Si_LVVl/
Au - NVV
Fig. 3. AuNVV and Si LVV Auger spectra taken from the Si on Au system of (a) 4 A, (b) 80 A and (c) 160 A Si fihns at successive stages of (1) as deposited, (2) 300 o C and (3) 350 ° C annealings for 2 rain.
about 200 A where the Si signal of fig. 1 showed that of the bulk Si. Next, in order to compare the silicide reaction at RT with that at higher temperature, we tried heat-treatments of the Si film on the Au substrate as a function of film thickness. Si films of (a) 4 A. (b) 80 )~, and (c) 160 A, were deposited on Au substrates at RT. The films were annealed at
3 0 0 ° C for 2 rain, then at 3 5 0 ° C for 2 min in the UHV chamber. Auger measurements of the films were made after each annealing. The Si EVV and A u N V V Auger spectra are shown in fig. 3. In (a) the 4 A Si film, the doublet peak features of the Si Auger spectra remained the same even after the annealings. In both (b) 80 A and (c) 160 A, the single Si peaks were transformed to the doublet
Fig. 4. SEM images for (a) 4 A, (b) 80 ,~ and (c) 160 .-~ Si films on Au substrates after the 3 5 0 ° C anneal of fig. 3. Markers represent 3.0 p.m.
K. Nishimori et al. / Interface reaction of Si thin film on Au
peak similar to that of spectrum e in fig. 2A after the annealings, as shown in spectra (b-3) and (c-3) of fig. 3. Therefore, for these Si film thicknesses, we can see the stable Au-rich silicide after annealing at 350 o C. The doublet peak features changed into the single peak after annealing at 420 ° C and then disappeared at more than 5 0 0 ° C for every film thickness. To observe the surface topography of the specimens after the annealing at 350 ° C in fig. 3, they were exposed to air during the transfer into the SEM apparatus. The observed SEM images are shown in fig. 4. The image of 4 A indicated a lot of black patches like amoebas. These patches were the ~pits formed on the grains of Au. In the case of 80 A Si film, the number of pits further increased due to the progressive reaction of Si with Au. When the Si film thickness was 160 A, the pits became the densest among the three pictures. It was reported that, in the Au deposition on Si(111), the pits appeared on the agglomerated Au islands by annealing at about 4 0 0 ° C [12]. The other specimens of 4, 80 and 160 ,~ Si films on Au without annealings were observed by SEM. Each SEM image showed that no pits appeared on the flat grains of Au. From the results of figs. 3 and 4, the black pits of SEM images can be considered to indicate the formation of stable Au-rich silicides by annealing at 350 ° C.
4. Conclusion We have studied the surface and interfacial reactions of Si film on Au substrate, using AES
369
and SEM. The AES measurement showed that S i - A u intermixing reaction takes place at the very beginning of Si deposition on Au at RT. The initial growth of Au-rich silicides was also observed in detail by using the difference spectrum technique. The SEM observation indicated numerous pits which were produced by the reaction of Si and Au after annealing at 350 o C.
Acknowledgement A part of this work was supported by Saneyoshi scholarship foundation.
References [1] A.K. Green and E. Bauer, J. Appl. Phys. 47 (1976) 284. [2] A. Hiraki, Surf. Sci. Rept. 3 (1984) 357. [3] G. Le Lay, M. Manneville and R. Kern, Surf. Sci. 65 (1977) 261. [4] A. Taleb-Ibrahimi, C.A. S6benne, D. Bolmont and P. Chen, Surf. Sci. 146 (1984) 229. [5] M. Hanbficken, Z. Imam, J.J. Mdtois and G. Le Lay, Surf. Sci. 162 (1985) 628. [6] H. Dallaporta and A. Cros, Surf. Sci. 178 (1986) 64. [7] K. Hricovini, J.E. Bonnet, B. Carriere, J.P. Deville, M. Hanbticken and G. Le Lay, Surf. Sci. 211/212 (1989) 630. [8] V.M. Bermudez, Surf. Sci. Lett. 230 (1990) L155. [9] A. Franciosi, D.W. Niles, G.M. Margaritondo, C. Quaresima, M. Capozi and P. Perfetti, Phys. Rev. B 32 (1985) 6917. [10] K. Nishimori, H. Tokutaka and K. Takashima, Surf. Sci. 100 (1980) 665. [11] P.W. Palmberg and T.N. Rhodin, J. Appl. Phys. 39 (1968) 2425. [12] T. Ichinokawa, Y. Ishikawa, M. Kenmochi, N. Ikeda, Y. Hosokawa and J. Kirschner, Surf. Sci. 176 (1986) 397.