JP3384487B2 - Method of forming insulating film and multilayer wiring - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an insulating film useful as an insulating film for insulating between multi-layered wirings of a semiconductor integrated circuit and a multi-layered wiring using this insulation film, and more particularly to a plasma-polymerized benzocyclobutene polymer The present invention relates to a method for forming an insulating film containing a plasma-polymerized organic polymer film, and multilayer wiring using this insulating film.

[0002]

2. Description of the Related Art The design rules of semiconductor integrated circuits have been continuously reduced, and along with this, the deterioration of performance due to wiring signal delay has become apparent. That is, the wiring signal delay of the semiconductor integrated circuit is the CR time constant of the wiring (C: wiring capacitance, R:
However, while the CR time constant of the wiring is increasing due to the increase of the wiring resistance due to the reduction of the wiring width and the increase of the inter-wiring capacitance due to the reduction of the wiring interval and the interlayer film thickness, As a result of the reduction of the device size and the speeding up of the operation of the device, it is becoming a reality that the wiring delay cannot follow the switching speed of the transistor. At present, an Al alloy is mainly used as a wiring material of a semiconductor integrated circuit, but a copper wiring or a silver wiring is more advantageous for reducing the resistance of the wiring. On the other hand, in order to reduce the capacitance between wires, the current silica (Si
An insulating film material having a dielectric constant lower than that of the O ₂ ) insulating film has been studied. As an insulating film having a low dielectric constant, an inorganic insulating film made of fluorine-added silica (SiOF) or porous silica and an organic polymer film (organic insulating film) are known. Therefore,
Fluorine-added silica has problems such as corrosion of wiring metal due to hydrofluoric acid due to reaction between fluorine in the film and water or hydrogen, and increase in dielectric constant due to fluorine escape. On the other hand, porous silica is expected to have a relative dielectric constant of 2 or less. However, there are problems that the relative dielectric constant increases and the dielectric strength voltage decreases due to the condensation of water in the minute holes.

Currently, there is an urgent need to develop an organic polymer film having excellent heat resistance and moisture absorption resistance as an interlayer insulating film / inter-wiring insulating film for insulating between multi-layered wirings on a semiconductor integrated circuit. For moisture resistance, it is important that the organic monomer does not contain a hydrophilic group, and it is desirable that the condensation polymerization reaction of water is not performed during the polymerization reaction from the organic monomer that is the skeleton of the organic polymer film. Has been done. As a method for growing this kind of organic polymer film, a spin coating method of an organic monomer and an evaporation method of an organic monomer are known. Here, the organic monomer refers to a monomer that causes a polymerization reaction with the organic monomer as a constituent unit to form an organic polymer (organic polymer). The spin coating method, which is the first conventional technique, is a method widely used for growing organic polymer films. In this case, the organic monomer is dissolved in the solvent, and the polymerization reaction of the monomer is caused by the removal of the solvent and the heat treatment (baking) of the raw material in the film forming process. As a result, a polymer film having a two-dimensional or three-dimensional crosslinked structure is formed. The skeleton that constitutes the product, the organic insulating film, is the structure of the organic monomer dissolved in the organic solvent.

[0004]

[Chemical 1]

[0005]

[Chemical 2]

For example, TM Stokich, Jr., WMLee, R.
A.Peters: “REAL-TIME FT-IR STUDIESOF THE REACTION
KINETICS FOR THE POLYMERIZATION OF DIVINYL SILOXAN
E BISBENZOCYCLO BUTENE MONOMERS "(Material Research
Symposium Proceedings Vol.227 pp.103-114, 1991)
In the method described in 1), a solvent prepared by dissolving the divinylsiloxane bis benzocyclobutene monomer shown in Chemical formula 1 in mesitylene is spin-coated and then baked at 100 ° C. to remove the mesitylene as a solvent. After that, when further heated to 300 ° C. to 350 ° C., the four-membered carbon ring in benzocyclobutene undergoes a thermal ring-opening polymerization reaction, as shown in Chemical formula 2,
A divinylsiloxane-bis-benzocyclobutene polymer film having a three-dimensional molecular chain having a skeleton of divinylsiloxane-bis-benzocyclobutene-monomer can be obtained.

As an example of the second prior art, Japanese Unexamined Patent Publication No. Hei 11
JP-17006-A proposes a method of evaporating an organic monomer and polymerizing the monomer in a gas phase on a substrate to obtain an organic insulating film. FIG. 13 is a schematic configuration diagram of an organic film growth apparatus proposed by the above publication by direct vaporization of organic monomers. Vaporizer 85 for organic monomer 1
It is introduced into the inside and heated under reduced pressure to evaporate the liquid organic monomer to generate the vaporized organic monomer 1a. Reaction chamber 8
The inside of 1 is decompressed by the exhaust pump 80 from the vaporizer 85 and the raw material pipe 86, and the vaporized organic monomer 1a
Is sent to the reaction chamber 81 through the raw material pipe 86. The vaporized organic monomer 1a is adsorbed on the surface of the semiconductor substrate 83 heated by the substrate heating unit 84, and is polymerized by the heat energy supplied from the substrate heating unit 84 to form a crosslinked structure, and the organic polymer film 82. To form.

FIG. 14 is a cross-sectional view of a conventional damascene multi-layer wiring formed using an organic polymer film. As shown in the figure, a first inter-wiring insulating film 92 made of an organic polymer is formed on a first interlayer insulating film 91 formed on a semiconductor substrate (not shown). In the wiring groove formed in 92, the first copper damascene wiring 93 is formed via the first barrier film 93a. A second interlayer insulating film 94 is formed on the second interlayer insulating film 94.
A copper via plug 95 is formed in the via hole formed in the interlayer insulating film 94 via the second barrier film 95a. Further, a second inter-wiring insulating film 96 made of an organic polymer is formed thereon, and a wiring barrier formed in the second inter-wiring insulating film 96 is covered with a third barrier film 97a. 2 copper damascene wiring 97 is formed. The wiring and via plug having such a damascene structure are manufactured as follows. After applying a photolithography method to form wiring trenches or via holes in the insulating film and depositing a conductive material such as a barrier film and copper, CMP (Chemical Mechanical Polishing: chemic
The conductive film on the insulating film is polished and removed by means of almechanical polishing), and the conductive material is embedded in the wiring groove or the via hole.

[0009]

However, the above-mentioned conventional techniques have the following technical problems. First, in the case of the spin coating method, which is the first conventional technique, an organic monomer is dissolved in a solvent, and this solvent is spin-coated. The spin coating film is heated in a baking oven to remove the solvent first, and then heated at a higher temperature to cause a polymerization reaction of the organic monomer to form an organic polymer film. Since the removal is performed by heating the semiconductor substrate coated with the solution, only the solvent is desorbed from the solution. Therefore, the solvent may remain in the coating solution, and the residual solvent may be desorbed during the heat treatment after film formation to peel off the wiring and insulating film formed on the upper layer, resulting in reliability. However, it causes a decrease in heat resistance. In addition, the spin coating method is referred to as an adhesion enhancer when the wettability of the monomer solution to the base substrate is poor, or when the adhesion between the formed film and the surface of the base semiconductor substrate is poor. It is necessary to apply the solution. Solvents are often used also in adhesion enhancers, and there is a possibility that the solvent may not be completely desorbed during heat treatment. Furthermore, the adhesion enhancer itself is the material with the lowest heat resistance in the film. Therefore, the heat resistance of the formed polymer film is deteriorated.

In the second prior art direct vaporization method for organic monomers, the organic monomer is kept in the vapor phase,
The carrier gas is transported onto the heated substrate. In this case, the organic monomers are adsorbed on the wafer surface, and these are diffused on the wafer surface to cause a polymerization reaction to form a polymer film. Generally, the re-vaporization temperature (heat-resistant temperature) of the organic polymer film decreases as the degree of polymerization decreases. When the substrate temperature is increased to accelerate the polymerization reaction, the adsorption efficiency of the monomer is significantly reduced, and the growth rate of the organic polymer film is reduced. If the growth substrate temperature is set sufficiently high, at least the heat resistant temperature of the obtained organic polymer film is expected to be equal to or higher than the growth substrate temperature. In the prior art, for example, Japanese Unexamined Patent Application Publication No. 11-17006 mentioned above. As described, it was not possible to set the substrate temperature to about 250 ° C., which was sufficiently high, so that an organic polymer film having high heat resistance could not be obtained.

As shown in FIG. 14, the lower the dielectric constant of the polymer organic film (first and second insulating film between wirings) existing between the wirings, the smaller the parasitic capacitance between the wirings. On the other hand, a barrier film and a copper film are formed on the surfaces of these inter-wiring insulating film films, and these conductive films are removed in the subsequent CMP process. At that time, sufficient mechanical strength and adhesiveness are particularly required for the base film (first and second inter-wiring insulating films) so that film peeling does not occur due to CMP stress. Further, the surface of the base film is directly polished for at least a certain period after the barrier film is removed. Mechanical strength that can withstand this CMP process is also required. Since lowering the dielectric constant of the organic polymer film lowers the mechanical strength, it is difficult to achieve both low dielectric constant and securing mechanical strength. For example, using two kinds of monomers, a polymer film having both a low dielectric constant and mechanical strength is formed by laminating a film having a low dielectric constant and a film having high mechanical strength, which have different chemical compositions. However, in this case, a plurality of vaporizers are required, which complicates the outer film forming process which increases the cost of the apparatus.

An object of the present invention is to solve the above-mentioned problems of the prior art. The object is, firstly, a deposition rate at which an organic polymer film having sufficient heat resistance can be put into practical use. Secondly, it is possible to efficiently form an organic polymer film having a low effective dielectric constant while securing mechanical strength.

[0013]

In order to achieve the above object, according to the present invention, vaporized benzocyclobutene monomer is introduced into a reaction chamber and placed on a heating stage in a plasma atmosphere. In the method for forming an insulating film, which comprises the step of forming a plasma-polymerized polymer film having the benzocyclobutene monomer as a skeleton on a substrate, the heating stage is heated to 350 ° C. or higher. A method for forming an insulating film is provided. Then, preferably, the film formation is performed in a low power plasma of 0.2 W / cm ² or less.

To achieve the above object, according to another aspect of the present invention, a vaporized organic monomer is introduced into a reaction chamber, and the organic monomer is placed on a substrate placed on a heating stage in a plasma atmosphere. In an insulating film forming method including a step of forming a plasma-polymerized polymer film containing a monomer in a skeleton, an insulating film formed by increasing a pressure of a film forming gas in the reaction chamber stepwise or continuously. Provided is a method for forming an insulating film, which comprises changing a physical property without changing a chemical composition of the film.

In order to achieve the above object, according to still another aspect of the present invention, a multi-layer wiring in which an inter-layer insulating film in which a conductive plug is embedded and an inter-wiring insulating film in which wiring is embedded are laminated. In at least one of the interlayer insulating film and the inter-wiring insulating film, the chemical composition is the same, the dielectric constant of the uppermost layer is higher than that of the lowermost layer, and the dielectric constant is stepwise or continuous. There is provided a multi-layered wiring, characterized in that it comprises a plasma polymerized polymer film which is made high.

[Operation] According to the present invention, the vaporized organic monomer is introduced into the low power plasma of 0.2 W / cm ² or less to partially polymerize the organic monomer in the vapor phase to obtain an effective molecular weight. To 350 ° C or higher, eg 4
Increase adsorption efficiency even on substrates heated to 00 ° C,
Moreover, by lowering the re-volatilization efficiency, it is possible to efficiently obtain a plasma polymerized polymer film having heat resistance of 400 ° C. or higher. Further, only by changing the growth pressure, a dense second plasma polymerized polymer film can be efficiently obtained from the vaporized gas of one kind of organic monomer on the first plasma polymerized polymer film having a relatively small dielectric constant. be able to. The first plasma-polymerized polymer film located on the underlayer is effective for reducing the parasitic capacitance between wirings, and the dense second plasma-polymerized polymer film located on the surface layer has sufficient mechanical strength to improve the CMP.
Mechanical damage in the process is suppressed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described in detail with reference to the drawings according to an embodiment. As an example, as an organic monomer, divinylsiloxane bis benzocyclobutene monomer (molecular weight: 390 g /
mol, hereinafter referred to as DVS-BCB monomer or BCB monomer) using MVP (Monomer-Vapor Polymeri)
A method for growing an organic polymer film by the zation method will be described.

[Embodiment 1] FIG. 1 is a schematic configuration diagram of a polymer film forming apparatus used in the plasma polymerization growth method of the present invention. This film forming apparatus is generally composed of an organic monomer tank 17, a liquid flow rate indicator 5, a vaporization controller 6, a carrier gas heating filter 8, gas flow rate controllers 7a and 7b, a reaction chamber 11, pipe heating heaters 12a and 12b, and cooling. It is composed of a trap 16, an exhaust pump 10, and a cleaning solvent tank 3. In addition, a carrier gas 2, a cleaning gas 34,
Pipes 35 to 40 for introducing and discharging the purge gas 19 and the pressure delivery gas 4 and valves 20 to 31 are provided.
Here, the organic monomer tank 17 is filled with DVS-BCB monomer as the organic monomer 1, and the cleaning solvent tank 3 stores mesitylene as the cleaning solvent 3a. Further, the carrier gas 2, the purge gas 19 and the pressure delivery gas 4 are all helium (He). The cleaning gas 34 is a mixed gas of SF ₆ and oxygen or ozone. Alternatively, a mixed gas of a fluorocarbon gas such as CF ₄ or C ₂ F ₆ and oxygen or ozone may be used.

Since the present invention relates to a method for producing an organic polymer film, in particular, a polymer film having improved heat resistance, the subsequent pipe cleaning process will not be mentioned in this specification. Therefore, there are valves and pipes that do not operate in the embodiments described below.

In describing the method of forming a plasma polymerized polymer film using the film forming apparatus of FIG. 1, first, a process of vaporizing an organic monomer that is liquid at room temperature by supplying a carrier gas will be described. In this device, a direct liquid injection system is adopted as the vaporization controller 6. The vaporization controller 6 has good thermal efficiency because vaporization is performed by heating a small amount of the organic monomer supplied into the vaporization controller, and in particular, like the BCB monomer, the saturated vapor pressure is low and the temperature is high. -It is extremely convenient when using an organic monomer that can easily undergo a polymerization reaction by heating for a long time. Further, it is an essential condition that the carrier gas 2 does not contain oxygen and water, but in the case of an organic monomer having a low saturated vapor pressure and being sensitive to temperature, it is desirable that the thermal conductivity is high. He is the most suitable, but Ar and N that do not react with organic monomers
₂ is acceptable.

The stable vaporization region of the organic monomer expands as the supply rate of the carrier gas 2 increases, while the polymerization rate of the organic monomer increases as the vaporization temperature rises, and the polymerization reaction in the vaporizer occurs. Prevent vaporization. That is, it depends on the relative relationship between the vaporization rate and the polymerization rate of the organic monomer, but the polymerization rate of the organic monomer is 100% of the vaporization rate.
If it is 1 minute or less, there is no practical problem. The specific vaporization condition range of the DVS-BCB monomer by the He carrier gas is 100 sccm to 3 carrier gas in the vaporization controller kept at a total pressure of 2666.4 Pa (20 Torr) or less.
Supplying 000 sccm, 0.1g-0.01g D per minute
VS-BCB monomer is supplied to the vaporization controller and 100 ° C
To 175 ° C. in the temperature range, in the present invention, the monomer is vaporized under this condition. When the vaporization rate can be made very high, for example, when the monomer is mixed with a carrier gas and then aerosolized to vaporize, the temperature inside the vaporizer is higher, for example, 200 ° C.
It is possible to

Next, from the vaporization of the DVS-BCB monomer by the polymer film forming apparatus shown in FIG.
A series of processes for forming a film will be described. First, in the initial state, the diaphragm valve 6a and the valves 20, 21, and 27 in the vaporization controller are "opened",
With the exhaust pump 10, the reaction chamber 11, the exhaust pipe 40, the waste liquid pipe 39, the vaporization controller 6, the liquid flow rate indicator 5, the vaporization raw material supply pipes 35a and 35b, and the organic monomer supply pipe 3
Evacuate 6c and 36d. Also, the pipe heater 1
The carrier gas supply pipe 38, the vaporization raw material supply pipes 35a and 35b, the waste liquid pipe 39, and the exhaust pipe 40 are the same as the set vaporization temperature of the organic monomer or the polymerization reaction of the organic monomer is remarkable (polymerization rate> 1%). /
Heat to a slightly higher temperature within the range of (minutes). For example, when the vaporization temperature of the DVS-BCB monomer is 150 ° C, the pipe heating temperature is 170 ° C. The temperature of the pipe is monitored by thermocouples 9a and 9b installed in various places of the pipe, and the pipe heater 12 keeps the set temperature constant.
a and 12b are controlled.

Next, the diaphragm valve 6a and the valve 21 in the vaporization controller are "closed" and the valves 28 and 20 are "open".
And the carrier gas (H
e) 2 is supplied to the vaporization controller 6 via the gas flow rate controller 7a and the carrier gas heating filter 8, and further flows into the reaction chamber 11 via the vaporization raw material supply pipes 35a and 35b, and is exhausted via the exhaust pipe 40. The pump 10 evacuates the apparatus.
Here, the vaporization controller 6 is heated to 150 ° C., and the He gas is heated by the carrier gas heating filter 8 to the same temperature as the vaporization temperature. By preheating the He gas introduced into the vaporization controller 6 to the vaporization temperature, reliquefaction of the vaporized DVS-BCB monomer due to the temperature decrease is prevented. Here, the preheating temperature of the carrier gas is basically the same as the vaporization temperature, but a temperature at which the polymerization reaction of the organic monomer does not become significant (polymerization rate> 1% / min), for example, D
With VS-BCB monomer, it is possible to raise the temperature to about 175 ° C. However, this preheating temperature also needs to be set so as not to exceed the heat resistant temperature (here, for example, 200 ° C.) of the valve used in the polymer film forming apparatus. Here, the vaporization temperature of the DVS-BCB monomer is 1
He carrier gas flow rate 50 from the vaporization characteristic curve of 50 ℃
It was set to 0 sccm. Under this condition, the total pressure P of the vaporization controller is 933.3 Pa (7 Torr), and the reaction chamber 1
1 was 266.6 Pa (2 Torr). In addition, the substrate heating unit 15 installed in the reaction chamber 11 heated the silicon substrate 14 on which the semiconductor integrated circuit was formed to 400 ° C.

After that, the valves 25 and 23 are opened, and the pressure delivery gas (He) 4 is applied from the organic monomer tank 17 to
The DVS-BCB monomer was supplied to the liquid flow rate indicator 5 through the organic monomer pipes 36a, 36b, 36c. Here, the feed rate of the DVS-BCB monomer is sent to the vaporization controller 6 while precisely controlling the feed rate. From the vaporization conditions of He carrier gas flow rate of 500 sccm and vaporization temperature of 150 ° C.,
The VS-BCB monomer feed rate was 0.03 g / min. At this stage, the diaphragm valve 6a in the vaporization controller is "closed". After that, the diaphragm valve 6a in the vaporization controller 6 is opened to vaporize the DVS-BCB monomer. The vaporized DVS-BCB monomer is mixed with the He carrier gas in the shower head 1 in the reaction chamber 11.
After being dispersed at 8, it is sprayed on the silicon substrate 14. When using the DVS-BCB monomer, the substrate heating temperature is preferably 350 ° C or higher, more preferably 400 ° C.
That is all. At this time, the substrate heating unit 15 and the shower head 18 are used as electrodes, and plasma generation high frequency power is applied to the shower head 18 to generate plasma between the substrate heating unit 15 and the shower head 18. The frequency of the plasma-generating high-frequency power was 13.56 MHz. This 13.5
A high frequency of 400 kHz may be superimposed on 6 MHz. The energy of the plasma promotes the ring-opening reaction of the carbon four-membered ring in benzocyclobutene in the gas phase, and
Opened DVS-BCB on the substrate surface heated to
The polymerization reaction of the monomers occurs to form the organic insulating film 13 which is a DVS-BCB polymer film.

By increasing the plasma-generating high-frequency power, the reaction is further promoted and the film formation rate is increased.
When the plasma-generating high-frequency power of 0.2 W / cm ² or more is applied, the DVS-BCB monomer itself begins to decompose, so that the plasma-generating high-frequency power has an optimum range. When the adsorption efficiency of the monomer becomes 25% as a result of the reaction being accelerated by the generation of plasma,
Growth of a 1 μm DVS-BCB film on an 8-inch substrate requires the supply of about 0.12 g of DVS-BCB monomer. Therefore, the flow rate of 0.
Feed 03 g / min DVS-BCB monomer for 4 minutes. At this time, unexposed DVS-BCB is introduced into the exhaust pipe 40.
Although the monomer is contained, the DVS-BCB monomer is reliquefied in the cooling trap 16 cooled to about 20 ° C. by water cooling and does not enter the exhaust pump 10. After vaporizing a predetermined amount of DVS-BCB monomer, the diaphragm valve 6a in the vaporization controller was closed. After that, the valve 28 is closed to stop the supply of the He carrier gas 2, and the silicon substrate 14 in the reaction chamber is taken out.

2 to 4 show the temperature-programmed desorption gas analysis (Temperatur) of plasma-polymerized DVS-BCB films having different substrate temperatures.
e Desorption Spectrometry (hereinafter referred to as TDS) spectrum. The horizontal axis represents the heating temperature and the vertical axis represents the measurement signal intensity. The pressure during film formation is 440 Pa (3.3 Tor).
r), input plasma generation high frequency power is 50 W (0.1
W / cm ² ). Since the signal intensity of the TDS spectrum depends on the measurement sample size and the film thickness, the signal intensity was standardized by the mass number 15 and the signal intensities among the samples were compared. Here, in particular, the mass numbers 2 (H ₂ ), 15 (CH ₃ ), 1
8 (H ₂ O), 28 (C ₄ H ₄ , Si, CO), 39 (C ₃
Only the spectra for H ₃ ), 51 (C ₄ H ₃ ) are shown. As shown in FIG. 2A, the film forming temperature Ts = 300 ° C.
Then, at a heating temperature of around 150 ° C, mass numbers of 15 and 3
Spectra of 9,51 are detected, showing that degassing from the membrane is present. Here, the film formation temperature Ts is the substrate temperature, and is actually the temperature measured by the substrate heating unit 15.

From the film forming temperature Ts of 300 ° C., Ts = 35
When the temperature is increased to 0 ° C., 375 ° C. and 400 ° C., FIG.
As shown in FIGS. 3C and 3D, FIG.
Mass number 15, 39 near the heating temperature of 150 ° C
Degassing of 51 does not occur. More specifically, by setting the film forming temperature to 350 ° C. or higher, the degassing amount near the heating temperature of 150 ° C. can be reduced to less than 1/1000.
Therefore, it can be seen that by setting the film forming temperature to 350 ° C. or higher, the amount of degassing at a low temperature is reduced and the heat resistance is improved. Further, the higher the film formation temperature, the more the mass number becomes 2, 15,
It can be seen that the degassing start temperature of each spectrum of 28, 39, 51 is shifted to the high temperature side, and the heat resistance is also improved. Further, for example, the mass number 51 at a heating temperature of 450 ° C.
The amount of desorbed gas is less than 1/100 when the film forming temperature is changed from 350 ° C to 400 ° C. Similarly, heating temperature 400
The amount of desorbed gas having a mass number of 39 at ℃ is 300 at the film formation temperature.
When the temperature changes from ℃ to 400 ℃, it becomes less than 1/100.

Further, a spectrum (mass number 18) expected to be water is detected near the heating temperature of 200 to 300 ° C. As shown in FIG. 2A, at Ts = 300 ° C.,
The spectrum of mass number 18 shows a peak near 250 ° C., but at Ts = 350 ° C., the peak shifts to around a heating temperature of 290 ° C. 2 at Ts = 375 ° C
Broad peak at 00-300 ° C and Ts
= 400 ° C., the peak intensity is remarkably reduced. It is considered that as the substrate temperature increases, the amount of water taken into the film during the film deposition process decreases and the hygroscopicity of the film decreases. A similar tendency is obtained even at Ts = 450 ° C. (see FIG. 4 (e)). From the above, it can be seen that the preferable film forming temperature is 350 ° C. or higher, more preferably 375 ° C. or higher, and the optimum film forming temperature is 400 ° C. or higher. In addition, when the high frequency power for plasma generation is not applied, D
The growth rate of the VS-BCB film is very slow, and there is a problem in practicality.

Thus, 0.1 W / c was added to the organic monomer.
By applying a low power plasma of about m ² to polymerize a part of the organic monomer in the gas phase to polymerize it,
The organic polymer film can be practically grown on the substrate heated to 0 ° C. or higher, and the polymer film having high heat resistance can be efficiently formed. In particular, the film formation temperature is 400 ° C
By this, a film having a heat resistance of 400 ° C. or higher and a very high thermal stability was obtained.

FIG. 5 and FIG. 6 are diagrams showing TDS spectra of films formed at a substrate temperature of 400 ° C. while changing the film forming pressure and the plasma generation high frequency power. Substrate temperature 4
At 00 ° C., FIG. 5A shows a film forming pressure of 400 Pa.
(3.0 Torr), plasma generation high frequency power 50
W, FIG. 5B shows a film forming pressure of 400 Pa (3.0 Tor).
r), plasma-generating high-frequency power 75 W, film-forming pressure 440 Pa (3.3 Torr) in FIG. 6C, plasma-generating high-frequency power 50 W, and film-forming pressure 440 Pa in FIG. 6D.
(3.3 Torr), Plasma generation high frequency power 75
W. It was found that the TDS spectra were almost the same under any of the film forming conditions, and similar heat resistance was obtained by setting the substrate temperature to 400 ° C.

FIG. 7 is a diagram showing an infrared absorption spectrum of a film obtained by the method for producing a polymer film according to the present invention.
The substrate temperature was 400 ° C., the high frequency power for plasma generation was 50 W and 75 W, and the pressure during film formation was 400 Pa.
(3.0 Torr) and 440 Pa (3.3 Torr
r). Peak 1470,1194cm ^-1 (benzocyclobutene groups) and 985cm ^-1 (vinyl group) is also due to the monomer structure in any of the film forming conditions are not observed, the monomer structure in the resulting film remained Absent. On the contrary, a peak at 1498 cm ⁻¹ due to tetrahydronaphthalene generated by the polymerization reaction was observed under any of the film forming conditions, and it can be seen that the BCB polymer was obtained when the film was formed at a substrate temperature of 400 ° C. FIG. 8 shows B obtained by further increasing the substrate temperature to 450 ° C.
It is an infrared absorption spectrum of a CB polymer film. Here, the plasma-generating high-frequency power is 0.1 W / cm ² , and the film forming pressure is 440 Pa (3.3 Torr). In each case, a characteristic absorption peak is recognized in the DVS-BCB polymer film. In this way, the substrate temperature is 400 ℃
By applying a low power plasma of 0.1 W / cm ² or less and polymerizing a part of the organic monomer without decomposing it, BCB having heat resistance of 400 ° C.
The polymer can be easily grown.

Example 2 FIG. 9 shows the relative permittivity (ε) of a BCB film at a substrate temperature of 400 ° C. obtained by the method for producing a polymer film according to the present invention. It can be seen that the relative permittivity becomes higher as the pressure becomes higher, regardless of the plasma generation high-frequency power. The dielectric constant of a substance is composed of electronic polarization, ionic polarization, and orientation polarization components. Under each film forming condition, as shown in FIGS. 7 and 8, FT-IR (Four
ier transform infrared absorption spectroscopy) Since there is no significant change in the measurement results and heat resistance, it is recognized that there is no significant difference in the film structure and chemical composition. Is considered to have increased. Furthermore, TOF-
SIMS (Time of Flight-Secondary Ion Mass Spe
In the analysis by ctrometry, 400 Pa (3.0 Tor)
The tetrahydronaphthalene group contained in the DVS-BCB polymer film formed in r) was 440 Pa (3.3 To).
In the DVS-BCB polymer film formed in rr), it tends to be changed to a naphthalene group,
It is considered that such a change in the partial chemical structure affects the change in the relative dielectric constant. In fact, 400 Pa (3.
C of DVS-BCB polymer film formed at 0 Torr)
The MP speed is a polishing pressure of 1.96 N / cm ² (0.2 kg /
Although it was about 100 nm / min in cm ² ),
The polymer film formed at 440 Pa (3.3 Torr) had excellent mechanical strength of 20 nm / min or less. Further, a TaN barrier film was grown on a DVS-BCB polymer film formed at 400 Pa (3.0 Torr), sliced into 1 mm square, and then a peeling test was performed with an adhesive tape. Adhesion failure was found in 25%. On the other hand, D formed at 440 Pa (3.3 Torr)
In the case of the VS-BCB polymer film, no poor adhesion was observed.

By utilizing this physical phenomenon, DVS-BCB laminated films having different properties can be easily obtained.
Specifically, the substrate temperature is 350 ° C. or higher, for example, 400
℃, plasma generated high frequency power 75W (0.15W /
cm ² ), the film formation pressure is 400 P at the initial stage of film formation.
A first plasma polymerized film (here, DVS-BCB polymer film) having a predetermined thickness is grown as a (3.0 Torr), and then the pressure is increased to 440 Pa (3.3 Torr) to perform the second plasma polymerization. Grow the film. In this way, by changing the growth pressure, it is possible to easily form a structure in which the second plasma polymerized film having a high density and a high mechanical strength is laminated on the first plasma polymerized film having a relatively low dielectric constant. can do. In this case, both the first and second plasma polymerized films are DVS-BCB polymers, which have the same chemical composition, but different densities and relative dielectric constants. As described above, according to the present invention, it becomes possible to form a polymer film having different physical / mechanical properties by only providing one vaporizer for vaporizing the DVS-BCB monomer, which increases the apparatus cost. It is possible to form a polymer film that has two features (low dielectric constant and mechanical strength) without doing so.

FIG. 10 is a schematic sectional view of a case where copper damascene wiring is formed on such a DVS-BCB polymer laminated film. This multilayer wiring was formed as follows. On the first interlayer insulating film 51 mainly composed of silicon oxide, the substrate temperature is set to 400 ° C., the high frequency power for plasma generation is kept constant at 75 W (0.15 W / cm ² ), and the deposition pressure is set to 400 Pa (3.0 Torr). After growing a plasma-polymerized DVS-BCB polymer film having a thickness of 300 nm as the first low dielectric constant film 52a, the pressure in the chamber was set to 4
The pressure is increased to 40 Pa (3.3 Torr), and the second low dielectric constant film 52a is similarly plasma-polymerized with a thickness of 200 nm D.
A VS-BCB polymer film was grown to form a first inter-wiring insulating film 52. After that, a wiring groove reaching a conductive plug (not shown) embedded in the first interlayer insulating film is opened by dry etching, and TaN is formed by a high frequency sputtering method.
_After depositing a laminated film of _0.1 / Ta ₂ N (20 nm thickness / 20 nm thickness) to form the first barrier film 53a, a 700 nm-thick copper film was grown by MOCVD. 400 in N ₂
After annealing at ℃, polishing pressure 1.96N / cm ² (0.2kg
/ Cm ² ) to remove the copper film and the barrier film on the first inter-wiring insulating film 52 to remove the first copper damascene wiring 5
Formed 3.

Next, as the second interlayer insulating film 54, a film thickness of 5 is obtained.
A 00 nm silicon oxide film is deposited by a CVD method, a via hole exposing the surface of the first copper damascene wiring 53 is opened in the second interlayer insulating film, and then TaN _0.1 / Ta ₂ N is formed.
50 nm consisting of (20 nm thickness / 20 nm thickness) laminated film
A thick second barrier film 55a and a 700 nm thick copper film were deposited. Next, the copper film and the barrier film on the second interlayer insulating film 54 were removed by CMP to form a copper via plug 55.
After that, a second inter-wiring insulating film 56 composed of the first low-dielectric-constant film 56a and the second low-dielectric-constant film 56b is formed by the same method as described above, and the second inter-wiring insulating film 56 is formed. After forming a wiring groove in the substrate, a third barrier film 57a and a copper film were deposited. Then, the barrier film and the copper film on the second inter-wiring insulating film 56 were removed by CMP to form the second copper damascene wiring 57. In the multilayer wiring thus manufactured, the relative dielectric constant of the DVS-BCB laminated film obtained from the capacitance between wirings was 2.57. This is a value that substantially coincides with the film thickness-weighted average value of the relative permittivity of the first plasma-polymerized film (2.51) and the relative permittivity of the second plasma-polymerized film (2.68). In addition, due to the presence of the dense second plasma-polymerized film in the upper layer, the film reduction amount of the DVS-BCB laminated film after CMP was suppressed to about 30 nm.

[Embodiment 3] In Embodiment 3, FIG.
Plasma-polymerized DV using the cluster type apparatus shown in FIG.
Following the S-BCB laminated film, an inorganic insulating film is formed thereon without breaking the vacuum, and this is used as a hard mask in the etching process. It is also used as a stopper in the CMP process. FIG. 11 is a schematic plan view showing the configuration of the cluster type device used in this embodiment. The present apparatus has a gate valve A76, a gate valve B77, a gate valve C78, and a gate valve D79 centered on a center chamber 73 equipped with a vacuum robot 72 that transfers wafers between the chambers in a vacuum.
A plurality of film formation reactors (here, the plasma polymerization film formation reactor 70 and the inorganic insulating film formation reactor 7 are divided by
Wafer load lock chamber A7
4 and a wafer load lock chamber B75. The number of wafer load lock chambers may be one. Further, an atmospheric robot for transferring the wafer to the load lock chamber in the atmosphere may be provided. Here, the center chamber 73 and the film formation reactors 70 and 71
Is evacuated.

First, a wafer is loaded into the load lock chamber A74 by an atmospheric robot (not shown).
After the load lock chamber A74 is evacuated to a vacuum, the wafer placed in the chamber is gate valve A76 by the vacuum robot 72 in the center chamber 73.
Via the gate valve B77 to the plasma polymerization film forming reactor 70.
Be transported to. After closing the gate valve B, in the plasma polymerization film forming reactor, the plasma polymerization film is formed on the wafer by the method shown in the first or second embodiment. Here, the substrate temperature at the time of forming the plasma polymerized film is set to be equal to or higher than the substrate temperature at the time of forming the insulating film in the subsequent insulating film forming reactor. After purging the reactor with an inert gas and subsequently vacuuming, the gate valve B is opened, the wafer on which the plasma polymerized film is formed is taken out from the plasma polymerized film forming reactor 70 to the center chamber 73 by the vacuum robot 72, and the gate valve B77 is opened. close.

Subsequently, the gate valve C78 is opened, and the wafer is transferred to the inorganic insulating film forming reactor 71 by the vacuum robot 72. After closing the gate valve C78, an insulating film, here a silicon oxide film, is formed in the inorganic insulating film forming reactor. As described above, the film formation temperature of the insulating film in the inorganic insulating film film formation reactor is set to be equal to or lower than the film formation temperature of the plasma polymerized film. Here, the plasma-polymerized film was formed at a substrate temperature of 400 ° C. and the silicon oxide film was formed at a substrate temperature of 400 ° C. After the film formation reactor was purged with an inert gas and then evacuated, the gate valve C78 was opened, and the wafer on which the silicon oxide film was formed on the plasma polymerized film was vacuum robot 72 from the inorganic insulating film film formation reactor 71 to the center chamber. Take out to 73 and close the gate valve C78. Next, the vacuum robot 72 transfers the wafer from the center chamber 73 through the gate valve D79 to the vacuum-loaded load lock chamber B75. After this, load lock chamber B
75 is returned to atmospheric pressure, and the wafer on which film formation has been completed is taken out by an atmospheric robot.

Wafers can be loaded into and unloaded from the load lock chamber together with the wafer cassette. In this case, a wafer cassette loaded with wafers is carried into the load lock chamber A74 by hand or by an atmospheric robot, and an empty wafer cassette is carried into the load lock chamber B in advance. After evacuating both load lock chambers to a vacuum, one wafer is taken out from the wafer cassette in the load lock chamber A by the vacuum robot 72, and film formation is performed via the film formation reactors 70 and 71. The wafer formed with the plasma polymerized film and the silicon oxide film is loaded into the load lock chamber B by the vacuum robot 72.
The wafer cassette in 75 is accommodated. Thereafter, similarly, the wafers stored in the wafer cassette in the load lock chamber A74 are taken out one by one to form a film, and the wafers for which the film formation is completed are stored in the wafer cassette in the load lock chamber B75. Film formation is performed on all the wafers, and after all the film-formed wafers are stored in the wafer cassette in the load lock chamber B75, the load lock chamber B75 is returned to atmospheric pressure and the film is formed manually or by an atmospheric robot. The wafer that has been completed is taken out in the state of being stored in the cassette. According to the method using the wafer cassette, while the film can be formed in the plasma polymerization film forming reactor 70, the film can be formed in the inorganic insulating film forming reactor 71 on another wafer, so that the film forming apparatus can be used. It is possible to improve efficiency and productivity. Even if this wafer cassette is not used,
If a plurality of wafers can be accommodated in the load lock chamber, the productivity can be similarly improved.

Depending on the wiring structure to be formed, after the silicon oxide film is formed on the plasma polymerized film, it may be transported again to the plasma polymerization reactor and the plasma polymerized film may be formed again on the silicon oxide film. It is also possible to repeat the above film formation several times. As described above, by continuously transporting in a vacuum and continuously forming the plasma-polymerized film and the inorganic insulating film, it becomes possible to form a multilayer laminated insulating film without exposing each interface to the atmosphere. It has been known that the interface of the plasma-polymerized film is easily affected by the atmosphere, particularly moisture and oxygen, and that if the plasma-polymerized film is exposed to the atmosphere before and after the formation of the plasma-polymerized film, film peeling at the interface easily occurs. In addition, there is concern that the dielectric strength may deteriorate and the dielectric constant may increase. As shown in this example, continuous film formation by vacuum transfer can prevent film peeling and improve hygroscopicity and chemical resistance.

12A to 12D are cross-sectional views in order of steps for explaining a method of manufacturing a damascene structure wiring formed by using the cluster type device shown in FIG. A first interlayer insulating film 61 made of a silicon oxide film having a film thickness of 1 μm is formed on a silicon substrate 60 on which a transistor (not shown) is formed, and penetrates the first interlayer insulating film 61 to contact a diffusion layer of a transistor. Contact plug 62 is formed [FIG.
(A)]. Then, the substrate temperature is set to 40 as in the second embodiment.
The plasma generation high frequency power is 75 W (0.1
5 W / cm ² ) and the pressure is 400 Pa.
(3.0 Torr), a 300 nm-thick plasma-polymerized DVS-BCB polymer film to be the first low dielectric constant film 63a is grown, and then the chamber internal pressure is 440 Pa.
The second low dielectric constant film 63 is raised to (3.3 Torr).
A 200 nm-thick plasma-polymerized DVS-BCB polymer film serving as b was grown to form an inter-wiring insulating film 63.
Then, the wafer was mounted in the inorganic insulating film deposition reactor without breaking the vacuum, and a silicon oxide film 64a for forming a hard mask was deposited to a thickness of 50 nm at a substrate temperature of 390 ° C. [FIG. b)]. A silicon nitride film may be formed instead of the silicon oxide film.

Then, a photoresist was spin-coated on the silicon oxide film 64a, exposed and developed to form a resist film 65 having openings in the wiring pattern to be formed [FIG. 12 (c)]. Next, the silicon oxide film 64a is selectively etched using the resist film 65 as a mask to form the hard mask 64, and then the resist film 65 is formed.
Then, the inter-wiring insulating film 63 was etched using the hard mask 64 as a mask to form a wiring groove 66. Here, the etching gas using CHF _3, instead of this CHF ₃
It may be used a mixed gas of O _2. In this case, although the etching shape tends to be tapered due to the presence of radical components during etching, the presence of the hard mask 64 makes it possible to obtain an opening having a good shape.
In the etching process for forming the wiring groove 66, the resist film 65 is simultaneously removed [FIG. 12 (d)]. Next, as in the second embodiment, TaN is formed by the high frequency sputtering method.
A laminated barrier film of _0.1 / Ta ₂ N (20 nm thickness / 20 nm thickness) is grown, and a 700 nm thick copper film is further MOCVD deposited.
Method, then anneal at 400 ° C. in N ₂ and use a slurry in which silica particles are dispersed to prepare a CM having a polishing pressure of 1.96 N / cm ² (0.2 kg / cm ² ).
The copper film and the laminated barrier film on the hard mask 64 were removed by P to form a copper damascene wiring 67 filling the wiring groove 66. At this time, since the hard mask 64 has high polishing resistance, it remains without being polished even after the completion of CMP. Further, since the silicon oxide film 64a is a film formed without breaking the vacuum and the underlying layer is the second low dielectric constant film 63b having high mechanical strength and good adhesion, it is possible to prevent The hard mask 64 will not be peeled off.

After forming the copper damascene wiring 67, in the inorganic insulating film deposition reactor of the cluster type device, the substrate temperature is set to 390 ° C. and the thickness of 50 nm is formed on the composite surface of the hard mask film 64 and the copper damascene wiring 67. A wiring protection film 68 made of a silicon nitride film was formed [FIG. 12 (e)]. Subsequently, the film is conveyed into the plasma polymerization film formation reactor without breaking the vacuum, and the substrate temperature is set to 400 ° C. in the same manner as the inter-wiring insulating film 63, and the first low dielectric constant film 69a and the second low dielectric constant film are formed. A second interlayer insulating film 69 including the film 69b was formed [FIG. 12 (f)]. If necessary, the second interlayer insulating film 69
A hard mask forming material layer such as a silicon oxide film or a silicon nitride film may be formed thereover. After that, the second interlayer insulating film 69 and the wiring protection film 68 are selectively etched to form a via hole exposing the surface of the copper damascene wiring 67, and a conductive plug is deposited by depositing a conductive film and CMP. Form. By repeating the above steps, it is possible to obtain a multilayer wiring structure using a polymer film having high heat resistance, low dielectric constant and high mechanical strength.

[0044]

As described above, according to the present invention, the film forming temperature is set to a high temperature of 350 ° C. or higher in the plasma atmosphere,
Since the benzocyclobutene polymer film is formed, a polymer film with high heat resistance and low dielectric constant can be obtained at a film formation speed that can be put to practical use. According to the embodiment in which the pressure in the chamber is increased during film formation, a plasma polymerized polymer film having a high dielectric strength, high mechanical strength and high adhesion can be easily laminated on the plasma polymerized polymer film having a low dielectric constant. Therefore, an inter-wiring / interlayer insulating film having both a low dielectric constant and CMP resistance can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a polymer film growth apparatus used in a first embodiment of the present invention.

FIG. 2 is a graph showing the T of the DVS-BCB polymer film obtained by the method for producing a polymer film according to the first embodiment of the present invention.
DS (temperature programmed desorption gas analysis) spectrum diagram (1).

FIG. 3 is a graph showing the T of the DVS-BCB polymer film obtained by the method for producing a polymer film according to the first embodiment of the present invention.
DS spectrum diagram (2).

FIG. 4 is a graph showing the T of the DVS-BCB polymer film obtained by the method for producing a polymer film according to the first embodiment of the present invention.
DS spectrum diagram (3).

FIG. 5 is a TDS spectrum diagram (part 1) for investigating the change in film quality of the DVS-BCB polymer film obtained by the first example according to the present invention with changes in input RF power and film formation pressure.

FIG. 6 is a TDS spectrum diagram (part 2) for studying the change in film quality of the DVS-BCB polymer film obtained by the first example according to the present invention with changes in input RF power and film formation pressure.

FIG. 7 is an infrared absorption spectrum diagram (1) of the DVS-BCB polymer film obtained by the first example according to the present invention.

FIG. 8 is an infrared absorption spectrum diagram (No. 2) of the DVS-BCB polymer film obtained by the first example according to the present invention.

FIG. 9 is a graph showing the relationship between the relative dielectric constant of the DVS-BCB polymer film obtained according to the second example of the present invention and the RF power condition / pressure condition applied during film formation.

FIG. 10 is a cross-sectional view illustrating a process of forming a multilayer wiring structure according to a second embodiment of the present invention.

FIG. 11 is a schematic configuration diagram of a cluster type film forming apparatus used in a third embodiment of the present invention.

FIG. 12 is a cross-sectional view in order of the steps, showing a process of forming a multilayer wiring structure according to a third embodiment of the present invention.

FIG. 13 is a schematic configuration diagram of a conventional polymer film growth apparatus.

FIG. 14 is a sectional view showing a conventional multilayer wiring structure.

[Explanation of symbols]

1 organic monomer 1a Gasified organic monomer 2 carrier gas 3 Cleaning solvent tank 3a Cleaning solvent 4 Pressure delivery gas 5 Liquid flow rate indicator 6 Vaporization controller 6a Diaphragm valve 7a, 7b Gas flow rate controller 8 Carrier gas heating filter 9a, 9b thermocouple 10 Exhaust pump 11 Reaction chamber 12a, 12b Pipe heater 13 Organic insulating film 14 Silicon substrate 15 Substrate heating unit 16 Cooling trap 17 Organic Monomer Tank 18 shower head 19 Purge gas 20 to 31 valves 34 Cleaning gas 35a, 35b Vaporization raw material supply pipe 36a-36d Organic monomer supply pipe 37a, 37b Cleaning solvent supply pipe 38 Carrier gas supply piping 39 Waste liquid piping 40 Exhaust pipe 41 Cleaning gas supply pipe 42 Matching Box 43 RF power supply 44 RF cable 45a, 45b Ground wire 51 First interlayer insulating film 52 First inter-wiring insulating film 52a First low dielectric constant film 52b Second low dielectric constant film 53 Copper damascene wiring 53a First barrier film 54 Second interlayer insulating film 55 Copper via plug 55a Second barrier film 56 Second inter-wiring insulating film 56a First low dielectric constant film 56b Second low dielectric constant film 57 Copper 2nd damascene wiring 57a Third barrier film 60 Silicon substrate 61 First interlayer insulating film 62 Conductive plug 63 Inter-wiring insulation film 63a First low dielectric constant film 63b Second low dielectric constant film 64 hard mask 64a Silicon oxide film 65 Resist film 66 wiring groove 67 Copper damascene wiring 68 Wiring protection film 69 Second interlayer insulating film 69a First low dielectric constant film 69b Second low dielectric constant film 70 Plasma polymerization deposition reactor 71 Inorganic insulating film deposition reactor 72 Vacuum robot 73 Center chamber 74 Road Lock Chamber A 75 Road Lock Chamber B 76 Gate valve A 77 Gate valve B 78 Gate valve C 79 Gate valve D 80 Exhaust pump 81 Reaction chamber 82 Organic polymer film 83 Semiconductor substrate 84 Substrate heating unit 85 vaporizer 86 Vaporization raw material piping 91 First interlayer insulating film 92 First inter-wiring insulating film 93 Copper damascene wiring 93a First barrier film 94 Second interlayer insulating film 95 Copper via plug 95a Second barrier film 96 Second inter-wiring insulation film 97 Copper damascene wiring 97a Third barrier film

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 2000-12532 (JP, A) JP 11-87342 (JP, A) JP 10-163317 (JP, A) JP 8-213378 (JP, A) JP-A-8-88223 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/312 H01L 21/314 H01L 21/316 H01L 21/318 B01J 19 / 08 C08G 61/02 H01L 21/768

Claims (14)

(57) [Claims] 1. A vaporized benzocyclobutene monomer is introduced into a reaction chamber, and the benzocyclobutene monomer is placed on a substrate placed on a heating stage in a plasma atmosphere.
A method of forming an insulating film, comprising the step of forming a plasma-polymerized polymer film containing a monomer in the skeleton, wherein the heating stage is heated to 350 ° C. or higher. 2. The method for forming an insulating film according to claim 1, wherein the high frequency power applied to generate plasma is 0.20 W / cm ² or less. 3. The method for forming an insulating film according to claim 2, wherein the benzocyclobutene monomer is introduced into the reaction chamber through a showerhead, and the high frequency power is applied to the showerhead. . 4. The method for forming an insulating film according to claim 1, wherein the high frequency voltage applied to generate plasma is a combination of two frequencies. 5. A step of introducing a vaporized organic monomer into a reaction chamber and forming a plasma-polymerized polymer film containing the organic monomer in its skeleton on a substrate placed on a heating stage in a plasma atmosphere. In the method of forming an insulating film, the pressure of the film forming gas in the reaction chamber is increased stepwise or continuously so that the physical properties of the insulating film to be formed are changed without changing the basic chemical composition. A method for forming an insulating film, which is characterized by varying. 6. The method for forming an insulating film according to claim 5, wherein the heating stage is heated to 350 ° C. or higher. 7. The method for forming an insulating film according to claim 1, wherein the benzocyclobutene monomer or the organic monomer is divinylsiloxane bisbenzocyclobutene monomer. . 8. The step of forming an inorganic insulating film is added to the step of forming the plasma polymerized polymer film, and a vacuum state is maintained between both film forming steps. The method for forming an insulating film according to any one of 1 to 7. 9. The step of forming an inorganic insulating film prior to the step of forming the plasma-polymerized polymer film, wherein a vacuum state is maintained between both film forming steps. 9. The method for forming an insulating film according to any one of 1 to 8. 10. A step of further forming a plasma polymerized polymer film is added to the step of forming the inorganic insulating film,
9. The inorganic insulating film forming step and the plasma polymerized polymer film forming step are repeated as necessary, and a vacuum state is maintained between the film forming steps. Method of forming insulating film. 11. The substrate temperature in the step of forming the inorganic insulating film is equal to or lower than the substrate temperature in the step of forming the plasma polymerized polymer film. The method for forming an insulating film as described in 1. 12. In a multilayer wiring in which an interlayer insulating film having a conductive plug buried therein and an inter-wiring insulating film having wiring buried therein are laminated, at least one of the interlayer insulating film and the inter-wiring insulating film is formed. One insulating film contains a plasma-polymerized polymer film that has substantially the same chemical composition and that the uppermost layer has a higher density than the lowermost layer and the density is increased stepwise or continuously. Multilayer wiring characterized by. 13. The interlayer insulating film or the inter-wiring insulating film has a thin inorganic insulating film as an upper layer or a lower layer of the plasma polymerized polymer film.
2. The multilayer wiring described in 2. 14. The multilayer wiring according to claim 12, wherein the plasma polymerized polymer film is a plasma polymerized benzocyclobutene film.