Organosilicon Derivatives of 1,1-Dimethylhydrazine: Novel Precursors of Thin-Film Dielectric Coatings

Full text of DOI:10.1023/A:1022527112583

Doklady Chemistry, Vol. 388, Nos. 4–6, 2003, pp. 47–49. Translated from Doklady Akademii Nauk, Vol. 388, No. 6, 2003, pp. 761–763.
Original Russian Text Copyright © 2003 by Rakhlin, Fomina, Mirskov, Kanaev, Larionova, Voronkov.
CHEMISTRY
Organosilicon Derivatives of 1,1-Dimethylhydrazine:
Novel Precursors of Thin-Film Dielectric Coatings
V. I. Rakhlin, A. N. Fomina, R. G. Mirskov, V. G. Kanaev, L. G. Larionova,
and Academician M. G. Voronkov
Received November 22, 2002
Upon decomposition in a plasma of a high-fre- the yield of compound IV reduces to 24% if
quency electric discharge, organosilicon derivatives dichloro(methyl)silane reacts with a fourfold excess of
containing Si–N fragment, such as hexamethyldisila- DMH, and the reaction results mainly in 1,1-
zane (Me3Si)2NH and hexamethylcyclotrisilazane bis[methyl(2',2'-dimethylhydrazino)silyl]-2,2-dimeth-
(Me2SiNH)3, produce on the surface of crystalline sili- ylhydrazine (V) (yield, 71%). This compound seems to
con and other semiconducting materials thin films of have been obtained earlier in a small yield; however, its
silicon nitride, which are widely used in microelec- structure has not been established [4]. Compound V
tronic technology [1–3].
results from the cross-linking of two molecules of an
unstable intermediate, methylchloro(2,2-dimethylhy-
drazino)silane (VI), with a DMH molecule according
to the scheme
We assumed that organosilicon derivatives of 1,1-
dimethylhydrazine (rocket fuel to be recovered at
present) having high saturated vapor pressure and a
necessary set of film-producing elements could be used
as promising precursors of silicon-containing thin-film
dielectric coatings.
MeHSiCl2 + 2Me2NNH2
MeHSiCl(NHMe2) + [Me2NHNH2]+Cl–,
With this purpose in view, we obtained and tested
compounds of general formula Me4 – nSi(HNNMe2)n
and Me3 – nHSi(NHNMe2)n, where n = 1, 2. Trime-
thyl(2,2-dimethylhydrazino)silane Me3SiNHNMe2 (I)
VI
2MeHSiCl(NHNMe2 ) + 3Me2NNH2
[MeHSi(NHNMe2 )]2NNMe2
and
dimethylbis(2,2-dimethylhydrazino)silane
V
Me2Si(NHNMe2)2 (II) were synthesized previously [4] in
50–70% yield by the reaction of chlorotrimethylsilane or
dichlorodimethylsilane with an excess of 1,1-dimethyl-
hydrazine (DMH). At the same time, the reaction of
methylhydrochlorosilanes, chlorodimethylsilane and
dichloro(methyl)silane, with DMH results in dime-
+ 2[Me2NHNH2]+Cl–.
The composition and the structure of compound V
were confirmed by the data of elemental analysis and
1H, 13C, and 29Si NMR. The 1H NMR spectrum of com-
pound V shows two doublets (0.20 and 0.21 ppm) of
Me–Si groups due to spin–spin coupling with the H–Si
proton (3J 2.56 Hz) and two singlet resonance signals of
N–Me groups (2.42 and 2.68 ppm) with an integrated
intensity ratio of 2 : 1, respectively. The proton reso-
nance of the H–Si group appears at 4.76 ppm as two
overlapping quadruplets (the difference in chemical
thyl(2,2-dimethylhydrazino)silane
Me2HSiNHNMe2
(III) and methylbis(2,2-dimethylhydrazino)silane
MeHSi(NHNMe2)2 (IV) in only 11% yield. The reac-
tion is complicated by the side reactions of substitution
of a dimethylhydrazino group for the hydrogen atom at
silicon and intermolecular condensation of resulting
products.
We have found that the yield of compounds I and II shifts is 0.01 ppm). In the 13C NMR spectrum, the
increases to 86% when chlorotrimethylsilane or dichlo- chemical shifts of the MeSi groups differ insignifi-
rodimethylsilane was added to an ether solution of cantly (–2.21 ppm and –2.41 ppm). The signals of car-
DMH cooled to 5°ë and the reaction mixture was bon atoms of the NHNMe2 groups are in lower field
heated under reflux for 1 h followed by filtration to (52.15 ppm) as compared with the resonance of the
remove DMH hydrochloride.
methyl groups of the silazanyl fragment, Si2N–NMe2.
In the 29Si NMR spectrum, both silicon nuclei give one
signal (–29.8 ppm). Slight differences in the chemical
shifts of protons and carbons of terminal symmetrical
dimethylhydrazino groups (0.01 ppm) are due to either
steric hindrances between the fragments of this
branched molecule or the existence of two diastereo-
meric forms.
Under the same conditions, chlorodimethylsilane
and dichloro(methyl)silane produce compounds III
and IV in 83 and 61% yields, respectively. However,
Favorskii Institute of Chemistry, Siberian Division,
Russian Academy of Sciences, ul. Favorskogo 1,
Irkutsk, 664033 Russia
0012-5008/03/0002-0047$25.00 © 2003 åÄIä “Nauka /Interperiodica”

48
RAKHLIN et al.
Parameters of deposited films produced from Me3SiNHNMe2 (I) and Me2HSiNHNMe2 (III)
Parameter
SiO2
Si3N4
PSG
Vapor–gas mixture composition
O2
I or III
N2 or NH3
I or III
Me3SiOP(OMe)2, O2
I or III
Layer deposition rate, Å/min
I: 90–186
III: 95–265
1.46
I: 100–1000
III: 100–1100
1.7–1.95
I: 1270–2268
III: 1940–2880
1.5
Refractive index
IR spectrum
1090 cm–1 (Si–O)
850 cm–1 (Si–N)
1050–1070 cm–1 (Si–O)
1325–1330 cm–1 (P=O)
1421–2366
Etching rate in BE*, Å/min
Etching rate in PCE**, Å/min
126–1673
220–340
70–1450
100–1270
920–960
* BE is a buffer etching solution (NH F + HF + H O).
4
2
** PCE is a plasmochemical etching medium (90% CF + 10% O ).
4
2
Compounds I–IV were studied as precursors for a three-necked flask equipped with a stirrer, dropping
deposition of silicon-containing thin-layer coatings by funnel, and reflux condenser; the solution was cooled to
decomposition in low-temperature plasma of a high- 5°ë, and a solution of 167 g (1.6 mol) of chlorotrime-
frequency electric discharge. Among these compounds, thylsilane in 200 mL of ether was added. The reaction
as expected, trimethyl(2,2-dimethylhydrazino)silane mixture was stirred for 1 h, heated under reflux for 1 h,
(I) and dimethyl(2,2-dimethylhydrazino)silane (III), and filtered, and the ether was distilled off. The yield of
which have the highest values of saturated vapor pres-
compound I was 113 g (86%), bp 98–100°C, n2D0
1.4016. Literature data [5]: bp 100°C, n2D0 = 1.4009,
d240 = 0.7692.
=
sure (bp 101 and 82°C, respectively), proved to be
promising reagents for thin-film technology. The depo-
sition of films based on compounds I and III onto sili-
con wafers was carried out on a UVP-2M setup. The
process was performed at 150–350°C. Depending on
the composition of the vapor–gas mixture (along with I
and III, we used the following gases: oxygen, nitrogen,
ammonia, and liquid volatile trimethylsilyl dimethyl
phosphite Me3SiOP(OMe)2), we obtained films of sili-
con dioxide, silicon nitride, and silicon dioxide doped
with phosphorus atoms (phosphosilicate glass). The
table shows the composition of the initial vapor–gas
mixtures, deposition conditions, and selected parame-
ters of the resulting coatings. The data of the table indi-
cate the applicability of the novel precursors for the
production of modern microelectronic devices.
For C6H16SiN2 anal. calcd. (wt %): C, 45.40; H, 12.19;
N, 21.18; Si, 21.23.
Found (wt %): C, 45.58; H, 12.26; Si, 21.36.
Dimethylbis(2,2-dimethylhydrazino)silane
Me2Si(NHNMe2)2 (II) was obtained from 37 g of 1,1-
dimethylhydrazine and 20 g of dichlorodimethylsilane
in 50 mL of ether. The yield of compound II was 13 g
(51%), bp 60°C (21 mmHg), n2D0 = 1.4287. Literature
data [6]: bp 62°C (22 mmHg), n2D0 = 1.4298, d420
0.8504. 1H NMR (CDCI3, δ, ppm): 0.02 (6H, Me–Si),
=
2.39 (12H, Me–N).
EXPERIMENTAL
Dimethyl(2,2-dimethylhydrazino)silane
Me2HSiNHNMe2 (III) was obtained from 150 g of
1,1-dimethylhydrazine and 119.2 g of chlorodimethyl-
silane in 250 mL of ether. The yield of compound III
1H and 29Si NMR spectra were recorded on a Bruker
DPX-400 spectrometer. The spectra were obtained for
10–20% solutions in CDCI3 using TMS, cyclohexane,
or hexamethyldisiloxane as an internal reference. Chem-
ical shifts are measured with an accuracy of 0.01 ppm
and reported on the δ scale.
1
was 121 g (83%), bp 80–82°C. H NMR (CDCl3, δ,
ppm): 0.17 (6H, Me–Si), 2.41 (6H, Me–N), 4.69 (2H,
H–Si).
For C4H14Si1N2 anal. calcd. (wt %): C, 40.63;
H, 11.93; N, 23.69; Si, 23.75.
GLC analysis was carried out on a Tsvet-500 chro-
matograph using a thermal conductivity detector, with
glass columns 3 m × 4 mm. The sorbent used was Iner-
ton-super with graining 0.125–0.150 mm, impregnated
with 10% PMS-1000.
Found (wt %): C, 39.98; H, 12.01; N, 23.48; Si, 24.53.
Methylbis(2,2-dimethylhydrazino)silane
MeHSi(NHNMe2)2 (IV). (1) The title compound was
obtained from 41 g of DMH and 40 g of
dichloro(methyl)silane in 200 mL of ether. The yield of
Trimethyl(2,2-dimethylhydrazino)silane
Me3SiNHNMe2 (I). Dimethylhydrazine (192 g, 3.2 mol)
dissolved in 200 mL of anhydrous ether was placed into compound IV was 34 g (61%), bp 71–73°C (33 mmHg),
DOKLADY CHEMISTRY Vol. 388 Nos. 4–6 2003

ORGANOSILICON DERIVATIVES OF 1,1-DIMETHYLHYDRAZINE
49
n2D0 = 1.4340. Literature data [4]: bp 44–45°C (10 mmHg),
For C8H28Si2N6 anal. calcd. (wt %): C, 36.33;
H, 10.67; N, 31.77; Si, 21.23.
n2D0 = 1.4348. H NMR (CDCl3, δ, ppm): 0.11 (3H,
1
Found (wt %): C, 36.63; H, 10.94; N, 31.21; Si,
21.49.
Me–Si), 2.43 (12H, Me–N), 4.38 (1H, H–Si).
For C5H18Si1N4 anal. calcd. (wt %): C, 37.00;
H, 11.18; N, 34.52; Si, 17.30.
REFERENCES
Found (wt %): C, 36.81; H, 11.02; N, 34.27; Si,
17.21.
1. Voronkov, M.G., Sulimin, A.D., Yachmenev, V.V.,
et al., Dokl. Akad. Nauk SSSR, 1980, vol. 251, no. 5,
pp. 1156–1159.
(2) The title compound was obtained from 86 g
(3.09 mol) of DMH and 100 g (0.77 mol) of
dichloro(methyl)silane in 300 mL of ether. The yield of
compound IV was 32 g (24%), bp 70–71°C (30 mmHg),
2. Voronkov, M.G., Sulimin, A.D., Yachmenev, V.I., et al.,
Dokl. Akad. Nauk SSSR, 1981, vol. 259, no. 5,
pp. 1130–1132.
n2D0
=
1.4340. Moreover, 71
g
(54%) of
3. Smirnova, T.P., Khramova, L.V., Belyi, V.I., et al.,
Vysokomol. Soedin., 1989, vol. 30, no. 1, pp. 164–169.
[CH3HSiNHN(CH3)2]2NN(CH3)2 (V) was isolated, bp
93°C (5 mmHg), n2D0 = 1.4540. Literature data [4]: bp
4. Sergeeva, Z.I. and Tszyan-Lan’, Se, Zh. Obshch. Khim.,
1963, vol. 33, no. 6, pp. 1874–1878.
105.5–106.5°C (9–9.3 mmHg), n2D0 = 1.4523, d420
=
5. Sergeeva, Z.I. and Tszyan-Lan’, Se, Zh. Obshch. Khim.,
0.9128. 1H NMR (CDCl3, δ, ppm): 0.20–0.21 (6H, Me–Si,
3J = 2.56 Hz), 2.42 (6H, NHNMe2), 2.68 (6H, NNMe2),
4.76–4.77 (1H, H–Si).
1962, vol. 32, no. 6, pp. 1887–1893.
6. Sergeeva, Z.I., Tszyan Sin-chzhan’, and Tsitovich, D.D.,
Zh. Obshch. Khim., 1960, vol. 30, no. 2, pp. 694–695.
DOKLADY CHEMISTRY Vol. 388 Nos. 4–6 2003