CN104201149B - Fluorine-containing porous low-dielectric constant composite film and preparation method thereof - Google Patents
Fluorine-containing porous low-dielectric constant composite film and preparation method thereof Download PDFInfo
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- CN104201149B CN104201149B CN201410423510.XA CN201410423510A CN104201149B CN 104201149 B CN104201149 B CN 104201149B CN 201410423510 A CN201410423510 A CN 201410423510A CN 104201149 B CN104201149 B CN 104201149B
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Abstract
The invention belongs to the technical field of manufacturing of integrated circuits, and particularly relates to a fluorine-containing porous low-dielectric constant composite film and a preparation method thereof. The preparation method comprises the steps of: regarding TEOS (Tetraethyl Orthosilicate) and LIMO (Dipentene) as liquid-state source precursors, regarding C2F6 as a fluorine source, adopting a PECVD (Plasma Enhanced Chemical Vapor Deposition) process, controlling technical parameters such as a substrate temperature, a radio frequency power, a working pressure intensity in a reaction cavity, proportion of the precursors and the fluorine source in a deposition process, and depositing to obtain a fluorine-containing inorganic-organic composite film; then performing suitable thermal annealing treatment on the film to enable partial organic component to be thermally decomposed so as to obtain the fluorine-containing porous low-dielectric constant composite film. In a test at the high temperature of 100 DEG C , the dielectric constant of the film is 2.37-2.75, and the leakage current density at the field intensity of 1 MV/cm is within a range from 10 <-8> to 10 <-9> A/sq.cm.. In addition, the film of such type also has excellent mechanical property. The fluorine-containing porous low-dielectric constant composite film is simple in process operation, is completely compatible with a back-end interconnecting process of an existing integrated circuit, and is an ideal candidate of an interconnecting medium.
Description
Technical field
The invention belongs to ic manufacturing technology field is and in particular to a kind of fluorine-containing porous low dielectric constant THIN COMPOSITE
Film and preparation method thereof, is applied to the inter-level dielectric in copper-connection.
Background technology
With the development of integrated circuit technique, there is high speed, the chip of high device density, low-power consumption and low cost is got over
More to become the major product of super large-scale integration.Now, the wire density in chip is continuously increased, conductor width and
Reduce away from continuous, this leads to the resistance (r) in the interconnection of chip rear end more and more obvious with the ghost effect that electric capacity (c) produces.Mesh
Before, industrial commonly used copper (cu) replaces aluminum (al) to be connected up, to reduce resistance；Using low-k (low-k
) the traditional silicon dioxide (sio of material replacement2) as in layer and interlayer dielectric, to reduce parasitic capacitance.
In contemporary scientific research and commercial production, low-k(advanced low-k materialsk) preparation of material mainly adopts
With the technology of plasma enhanced CVD (pecvd), to traditional sio2Material is modified and obtains.It is concrete
Solution mainly has: introduces fluorine element, introduces hydrocarbon group (chx), introduce hole etc..Earliest low-kMaterial is that fluorine is mixed
Miscellaneous silicon dioxide (f-sio2), it is used on 180 nm and 130 nm technology nodes.The incorporation of fluorine element can replace sio2
Middle part oxygen element, forms the relatively low si-f key of polarizability, thus realizing the reduction of dielectric constant.Si-f key is highly stable, and one
As will not thermally decompose during following process, but Oil repellent is too high to lead to thin film easily to absorb water.Additionally,
During pecvd, the introducing of fluorine element is simple, need not do larger change to existing equipment and technique.
Porous membrane has also obtained extensive research in recent years, and the introducing of hole can reduce the density of material, thus dropping
Low-k.At present, the porous low dielectric constant material of open report is mainly the sicoh material of porous, for pecvd side
Method prepares fluorine-containing porous low dielectric constant films, and there is not been reported.Therefore, the present invention is with tetraethoxysilane (teos) and double
Amylene (limo) as liquid source presoma, with perfluoroethane (c2f6) as Fluorine source, adopt and existing integrated circuit fabrication process
Mutually compatible pecvd technology, and the post-depositional heat treatment of combination film, has prepared fluorine-containing porous low dielectric constant THIN COMPOSITE
Film.This thin film also has good insulating properties and mechanical property, disclosure satisfy that the performance to medium for the integrated circuit back-end interconnection
Require.
Content of the invention
Dielectric material of interconnection demand and preparation method thereof can be met it is an object of the invention to provide a kind of, that is, fluorine-containing
Porous low dielectric constant laminated film and preparation method thereof.
Fluorine-containing porous low dielectric constant laminated film proposed by the present invention, is with tetraethoxysilane (teos) and dipentene
(limo) as liquid source presoma, with perfluoroethane (c2f6) as Fluorine source, using pecvd technique, obtain inorganic-organic multiple
Close thin film.Then, thermal anneal process is carried out to this thin film so that part organic component thermally decomposes, thus obtaining fluorine-containing
Porous low dielectric constant inorganic-organic hybrid thin film.
The preparation method of fluorine-containing porous low dielectric constant laminated film proposed by the present invention, specifically comprises the following steps that
(1) wafer is placed in the reaction chamber of pecvd, then to reaction cavity evacuation, makes chamber pressure be less than 0.02
torr；Then, by heating system by silicon to 150 ~ 300 DEG C, and remain stable；
(2) it is passed through presoma teos and limo in reaction cavity, both flows are 0.1 ~ 2 g/min；Adopt first
Presoma is made to vaporize with carburator, wherein the vapourizing temperature of teos is 120 ~ 160 DEG C, the vapourizing temperature of limo is 60 ~ 100
℃；Then using carrier gas (as helium), precursor vapor is transported to reaction chamber from different gas circuits, wherein conveys teos steam
Carrier gas flux be 500 ~ 5000 sccm, conveying limo steam carrier gas flux be 1000 ~ 8000 sccm；
(3) it is passed through c through single pipeline in reaction cavity2f6Gas, flow is 10 ~ 2000 sccm；
(4) carry out plasma-reinforced chemical phase deposition, in deposition process, technological parameter is respectively as follows: radio-frequency power 100 ~ 700
w；Operating pressure 1 ~ 8 torr in reaction chamber；Polar plate spacing 10 ~ 20 mm, obtains fluorine-containing inorganic-organic hybrid thin film up and down；
In this fluorine-containing inorganic-organic hybrid thin film, inorganic constituentss are mainly si-o-si structure, and organic principle is mainly
Chx group；F is mainly combined with si, presented in si-f key in thin film；
(5) the inorganic-organic hybrid thin film obtaining pecvd deposition is placed in tube furnace, batch-type furnace or other cavitys, enters
Row thermal anneal process, annealing temperature is 400 ~ 600 DEG C, and annealing time is 0.5 ~ 4 hour, and annealing atmosphere can be argon, helium
Or nitrogen etc., pressure is 0.1 ~ 800 torr.In annealing process, part organic component occurs thermal decomposition to remove, and si-f key
Will not decompose, be derived from fluorine-containing porous compound film.
Above-mentioned thin film is carried out with electricity and Mechanics Performance Testing, gained performance is as follows: dielectric constant is 2.3 ~ 2.8,1
Leakage current density under mv/cm field intensity is 10-7~10-9a/cm2In the range of, Young's moduluss are 6 ~ 9 gpa, and hardness is 0.5 ~ 1.0
gpa.
The present invention has the advantage that
The method being provided using the present invention, successfully can be introduced the hole of nanoscale in thin film, and introduce fluorine unit
Element.Low-k, good insulating properties and excellent mechanical property are had by thin film prepared by the method.
The method that the present invention provides is mutually compatible with existing integrated circuit processing technique, and prepared thin film can be directly used as core
Inter-level dielectric in the interconnection of piece rear end.Technique manipulation is simply easy, by adjusting process parameter, can efficiently control thin film
Composition, chemical constitution, porosity etc., reach the purpose of the performances such as electricity, the mechanics of regulation and control low-k thin film.
Brief description
Fig. 1 is different c in deposition process2f6Infrared spectrogram after thermal anneal process for the thin film obtained by gas flow.
Fig. 2 is to work as c in embodiment 12f6Dielectric constant for the thin film obtained by 300 sccm and the change curve of voltage.
Fig. 3 is to work as c in embodiment 12f6Leakage current density for the thin film obtained by 300 sccm and the change of electric field intensity
Curve.
Specific embodiment
Embodiment 1
During pecvd, underlayer temperature is 200 DEG C, and in reaction chamber, operating pressure is 3 torr, and deposition power is 300
w.Reaction raw materials are teos, limo and c2f6, wherein, the flow-rate ratio of teos and limo is Grams Per Minute for 1:1.25(flux unit
Clock), their vapourizing temperature is respectively 160 DEG C and 100 DEG C；With helium as carrier gas after vaporization, they are each led into anti-
Answer in chamber, required carrier gas flux is respectively 2000 sccm and 5000 sccm；c2f6Gas is imported to instead by single gas piping
Answer in chamber, its flow is 100 ~ 500sccm.When thickness through the fluorine-containing inorganic-organic hybrid thin film obtained by pecvd is by depositing
Between determine.Then, by the thin film being deposited in nitrogen (n2) carrying out thermal anneal process under atmosphere, air pressure is about 1 atmospheric pressure, nitrogen
Throughput is about 1 l/min, and annealing temperature is 450 DEG C, and annealing time is 2 h.3 kinds of differences are employed in the present embodiment 1
c2f6Flow, respectively 100 sccm, 300 sccm, 500 sccm, gained thin film is respectively designated as sample 1, sample 2, sample 3.
Embodiment 2
During pecvd, underlayer temperature is 200 DEG C, and in reaction chamber, operating pressure is 3 torr, and deposition power is 300
w.Reaction raw materials are teos and limo, and the two flow-rate ratio is gram/minute for 1:1.25(flux unit), they are respectively at 160 DEG C
Be carrier gas by helium after 100 DEG C of vaporizations, be directed in reaction chamber, required carrier gas flux is respectively 2000 sccm and 5000
sccm.Then, by the thin film being deposited in nitrogen (n2) carrying out thermal anneal process under atmosphere, air pressure is about 1 atmospheric pressure, nitrogen
Flow is about 1 l/min, and annealing temperature is 450 DEG C, and annealing time is 2 h.The porous that obtained thin film is not fluorine-containing is thin
Film, as comparative sample.
In order to obtain the electric property of above-mentioned thin film, (resistivity is for 0.001 ~ 0.005 with low-resistivity silicon chip for the present invention
ω cm) it is substrate, using the aluminum of electron beam evaporation as top electrode material, wherein top electrode is the circular electrode of 400 μm of diameter.
By to aluminum/lowkThe measurement of capacitance-voltage (c-v) curve of thin film/silicon substrate/aluminum (mism) structure is normal to extract dielectric
Number, and average dielectric constant values are obtained by multi-point sampler.Thin by obtaining to the measurement of current-voltage (i-v) curve
The leakage current characteristic of film.In order to exclude the impact to thin film electrical property for the physical absorption water, before test, first sample is placed in n2/h2Atmosphere
In, carry out the annealing of 30min under the conditions of 400 DEG C, at 100 DEG C, then carry out electric performance test.Using nano impress
Test and to obtain the mechanical property (Young's moduluss and hardness) of thin film, the film thickness for nano-indenter test is that 600 nm are left
The right side, compression distance is the 1/10 of film thickness.
Fig. 1 is different c2f6The infrared spectrogram of the thin film that traffic income arrives, 1140 cm-1One is nearby had significantly to take on
Peak, from the absorption of vibrations of cage modle si-o-si, shows the presence of thin film mesopore.With c2f6The increase of flow, 941 cm-1The absorption peak strength nearby characterizing si-f key increases, and shows that the incorporation of f element in thin film increases；Meanwhile, si-o-si
Absworption peak moves to high wave number direction, and the incorporation that this also show more f leads to the increase of si-o bond strength.Table 1 lists reality
Apply the performance of sample in sample and embodiment 2 in example 1 it can be seen that introducing c in the reactor chamber2f6The k of gained thin film can be reduced
Value.Work as c2f6Flow is minimum by the k value of thin film obtained during 300sccm, reaches 2.37, and leakage current density very little.Additionally, should
Sample (sample 2 in embodiment 1) also has better than the Young's moduluss in embodiment 2, and close hardness, as shown in table 2.Figure
2 is the relation curve with voltage for the dielectric constant (k) of sample 2, indicates k value between 2.36 ~ 2.38.Fig. 3 is in embodiment 1
The leakage current density of sample 2 and the relation of extra electric field, when electric field intensity is for 1.5mv/cm, its leakage current density is still 10-8
a/cm2The order of magnitude.
Table 1
Table 2
| Sample | c2f6Flow (sccm) | Young's moduluss (gpa) | Hardness (gpa) |
| Embodiment 2 | 0 | 6.65 | 0.59 |
| Embodiment 1 | 300 | 7.28 | 0.51 |
Claims (1)
1. a kind of preparation method of fluorine-containing porous low dielectric constant laminated film it is characterised in that: using teos and limo as
Liquid source presoma, with c2f6As Fluorine source, using pecvd process deposits, specifically comprise the following steps that
(1) wafer is placed in the reaction chamber of pecvd, to reaction cavity evacuation, makes chamber pressure be less than 0.02 torr；So
Afterwards, by heating system by silicon to 150 ~ 300 DEG C, and remain stable；
(2) it is passed through presoma teos and limo in reaction cavity, both flows are 0.1 ~ 2 g/min；Initially with vapour
Changing device makes presoma vaporize, and wherein the vapourizing temperature of teos is 120 ~ 160 DEG C, and the vapourizing temperature of limo is 60 ~ 100 DEG C；So
Using carrier gas, precursor vapor is transported to reaction chamber from different gas circuits afterwards, the carrier gas flux of wherein conveying teos steam is
500 ~ 5000 sccm, the carrier gas flux of conveying limo steam is 1000 ~ 8000 sccm；Wherein, teos is tetraethoxysilane,
Limo is dipentene；
(3) it is passed through c through single pipeline in reaction cavity2f6Gas, flow is 10 ~ 2000 sccm；
(4) carry out plasma reinforced chemical vapour deposition, in deposition process, technological parameter is respectively as follows: radio-frequency power 100 ~ 700
w；Operating pressure 1 ~ 8 torr in reaction chamber；Polar plate spacing 10 ~ 20 mm, obtains fluorine-containing inorganic-organic hybrid thin film up and down；
(5) the inorganic-organic hybrid thin film obtaining pecvd deposition is placed in tube furnace, batch-type furnace or other cavitys, carries out heat
Annealing, annealing temperature is 400 ~ 600 DEG C, and annealing time is 0.5 ~ 4 hour, and annealing atmosphere is argon, helium or nitrogen,
Pressure is 0.1 ~ 800 torr, is derived from fluorine-containing porous low dielectric constant laminated film.
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101651131A (en) * | 2009-09-17 | 2010-02-17 | 复旦大学 | Low dielectric constant insulating film and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101651131A (en) * | 2009-09-17 | 2010-02-17 | 复旦大学 | Low dielectric constant insulating film and preparation method thereof |
Non-Patent Citations (1)
| Title |
|---|
| Effect of F- and CH-Doped on Dielectric Properties of SiCOH Films Deposited by Decamethylcyclopentasiloxane Electron Cyclotron Resonance Plasma;Ye Chao et al;《Chinese Physics Letters》;20051231;第22卷;2670-2673 * |
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