JP2016129259A - Semiconductor device manufacturing method and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a deposition speed of a porous insulation film and improve film strength of the porous insulation film.SOLUTION: A porous insulation film is formed by: vaporizing two and more organosiloxane materials having structures different from each other, in which each organosiloxane material has an annular SiO structure as a main skeleton; and transferring the organosiloxane materials to a reacting furnace (chamber CMB) together with a carrier gas; adding oxygen atom-containing oxidant gas to form a porous insulation film in the reacting furnace (chamber CMB) by plasma CVD(Chemical Vapor Deposition) or plasma polymerization. In the above-described process, a ratio of a flow rate of the added oxidant gas to a flow rate of the carrier gas is more than 0 and not more than 0.08.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor device manufacturing method and a semiconductor device.

  In recent years, various methods have been proposed to reduce the relative dielectric constant of an interlayer insulating film.

  In Patent Document 1 (Japanese Patent Laid-Open No. 2010-21575), a vapor obtained by diluting a vapor of a cyclic organic silica compound (cyclic organic siloxane raw material) with a rare gas and an oxidant gas at a flow rate of 0. A method for producing a porous insulating film is described in which a porous insulating film is grown by adding 3 to 1.2 times and introducing it into plasma. Accordingly, it is said that an insulating film having a low relative dielectric constant can be obtained stably.

  Patent Document 2 (International Publication No. 2007/032261 pamphlet) uses a mixed gas of a cyclic organic siloxane raw material and a compound raw material including a part of a chemical structure constituting the cyclic organic siloxane raw material, to form a plasma gas phase. A method of forming a porous insulating film by a growth method is described. Thereby, it is said that a porous insulating film in which hydrocarbon desorption is suppressed can be obtained.

  Patent Document 3 (International Publication No. 2008/010591 pamphlet) describes the following method for forming an insulating film. A raw material having a three-membered cyclic SiO structure in the main skeleton and a raw material having a four-membered cyclic SiO structure in the main skeleton are used. At least one of the two kinds of raw materials has at least one unsaturated hydrocarbon group in the side chain. Thereby, it is said that a porous insulating film realizing high strength and high density can be obtained.

  Patent Document 4 (Japanese Patent Laid-Open No. 2011-192962) describes the following method for manufacturing a semiconductor device. First, two or more kinds of organic siloxane compound raw materials each having a cyclic SiO structure as a main skeleton and having different structures are mixed and vaporized. Next, using the vaporized gas in a reaction furnace, a porous insulating film is formed by a plasma CVD (Chemical Vapor Deposition) method or a plasma polymerization method. Thereby, it is said that the dielectric constant of an insulating film can be reduced easily.

JP 2010-21575 A International Publication No. 2007/032261 Pamphlet International Publication No. 2008/010591 Pamphlet JP2011-192962A

  In recent years, it is further desired to increase the deposition rate of the porous insulating film. The present inventors have found that it is difficult to increase the deposition rate of the porous insulating film and to improve the film strength of the porous insulating film. Other problems and novel features will become apparent from the description of the specification and the accompanying drawings.

  According to one embodiment, a method for manufacturing a porous insulating film has the following characteristics. Two or more types of organosiloxane raw materials each having a cyclic SiO structure as the main skeleton are vaporized, transported together with a carrier gas to a reaction furnace, an oxidant gas containing oxygen atoms is added, and plasma CVD is performed in the reaction furnace A porous insulating film is formed by (Chemical Vapor Deposition) method or plasma polymerization method. In the step, the flow rate ratio of the added oxidant gas to the flow rate of the carrier gas is greater than 0 and 0.08 or less.

According to one embodiment, the porous insulating film has the following characteristics. It includes Si, O, C, and H, a cyclic SiO structure, and unsaturated and branched hydrocarbon groups bonded to Si. Further, FTIR (Fourier Transform Infrared Spectroscopy) peak area ratio of the peak of CHx wavenumber 2900 cm ^-1 vicinity against -Si-O-Si- peak at a wavenumber of 1100 cm ^-1 vicinity obtained by method is 0.23 or more.

  According to one embodiment, a method for manufacturing a semiconductor device has the following characteristics. Two or more types of organosiloxane raw materials each having a cyclic SiO structure as the main skeleton are vaporized, transported together with a carrier gas to a reaction furnace, an oxidant gas containing oxygen atoms is added, and plasma CVD is performed in the reaction furnace A porous insulating film is formed by a (Chemical Vapor Deposition) method or a plasma polymerization method (porous insulating film forming step). In the porous insulating film forming step, the flow rate ratio of the added oxidant gas to the carrier gas flow rate is greater than 0 and 0.08 or less.

According to one embodiment, a semiconductor device includes a porous insulating film including Si, O, C, and H, a cyclic SiO structure, and an unsaturated hydrocarbon group and a branched hydrocarbon group bonded to Si. And a wiring or a via provided in the porous insulating film. Further, FTIR (Fourier Transform Infrared Spectroscopy) peak area ratio of the peak of CHx wavenumber 2900 cm ^-1 vicinity against -Si-O-Si- peak at a wavenumber of 1100 cm ^-1 vicinity as determined by methods of the porous insulating film is 0 .23 or more.

  According to the embodiment, it is possible to increase the film forming speed of the porous insulating film and improve the film strength of the porous insulating film while maintaining the relative dielectric constant.

It is a schematic diagram which shows the structure of the semiconductor manufacturing apparatus which concerns on 1st Embodiment. 1 is a cross-sectional view illustrating a configuration of a semiconductor device according to a first embodiment. It is sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 1st Embodiment. It is sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 1st Embodiment. It is sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 1st Embodiment. It is the figure which showed the relationship between the flow volume of oxidizing agent gas, and the film-forming rate of a porous insulating film. It is the figure which showed the relationship between the flow volume of carrier gas and the film-forming rate of a porous insulating film. It is the figure which showed the relationship between the oxidizing agent gas flow rate ratio with respect to carrier gas flow rate, and the film-forming rate of a porous insulating film. It is the figure which showed the relationship between the oxidizing gas flow ratio with respect to carrier gas flow volume, and the film | membrane intensity | strength of a porous insulating film. It is a figure for demonstrating the characteristic of the porous insulating film which concerns on 2nd Embodiment. It is a figure for demonstrating the characteristic of the porous insulating film which concerns on 2nd Embodiment. It is sectional drawing which shows the structure of the semiconductor device which concerns on 4th Embodiment. It is sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 4th Embodiment. It is sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 4th Embodiment. It is sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 4th Embodiment. It is sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 4th Embodiment. It is sectional drawing which shows the structure of the semiconductor device which concerns on 5th Embodiment. It is sectional drawing which shows the structure of the semiconductor device which concerns on 6th Embodiment. It is a figure for demonstrating the characteristic of the semiconductor device which concerns on 6th Embodiment. It is a figure for demonstrating the characteristic of the porous insulating film which concerns on 3rd Embodiment. It is a figure for demonstrating the characteristic of the porous insulating film which concerns on 3rd Embodiment. It is a figure for demonstrating the characteristic of the porous insulating film which concerns on 3rd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

(First embodiment)
In the method for manufacturing a porous insulating film and the method for manufacturing a semiconductor device SD according to the first embodiment, two or more types of organic siloxane raw materials having a cyclic SiO structure as a main skeleton and different structures are vaporized, and a reaction furnace together with a carrier gas Transported to (chamber CMB), an oxidant gas containing oxygen atoms is added, and a porous insulating film is formed in the reaction furnace (chamber CMB) by plasma CVD (Chemical Vapor Deposition) method or plasma polymerization method (porous) Insulating film forming step). In the porous insulating film forming step, the flow rate ratio of the added oxidant gas to the carrier gas flow rate is greater than 0 and 0.08 or less. Thereby, the film formation rate of the porous insulating film can be increased and the film strength of the porous insulating film can be improved.

(Porous insulation film manufacturing equipment or semiconductor manufacturing equipment)
First, the semiconductor manufacturing apparatus SME according to the first embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram showing the configuration of the semiconductor manufacturing apparatus SME according to the first embodiment. The semiconductor device SD according to the first embodiment is manufactured using the following semiconductor manufacturing apparatus SME. The semiconductor manufacturing apparatus SME is an apparatus for forming a porous insulating film by, for example, a plasma CVD method or a plasma polymerization method. The “semiconductor manufacturing apparatus SME” here is not limited to a semiconductor device, and may be a porous insulating film manufacturing apparatus for forming a single-layer porous insulating film.

  As shown in FIG. 1, the reaction furnace (chamber CMB) is connected to the vacuum pump VP via the exhaust pipe PPV, the exhaust valve VV6, and the cooling trap CT. Thereby, the inside of the chamber CMB can be decompressed by operating the vacuum pump VP.

  Further, a throttle valve (not shown) is provided between the chamber CMB and the vacuum pump VP. By controlling the opening / closing degree of the throttle valve, the pressure in the chamber CMB can be controlled.

  A stage STG having a heating function is provided in the chamber CMB. On the stage STG, a deposition target substrate (for example, a semiconductor substrate SUB) is placed. The stage STG can be heated.

  The organosiloxane raw material used in the first embodiment is sealed in the raw material reservoir tank TNK in a liquid state. In this raw material reservoir tank TNK, for example, two types of organic siloxane raw materials described later are mixed. A raw material reservoir tank TNK may be individually provided for each organic siloxane raw material. In this case, piping for supplying raw materials and the like may be provided individually for each raw material. Details of the structure of the organic siloxane raw material will be described later.

The raw material (organic siloxane raw material) is pumped from the raw material reservoir tank TNK through a pipe (not shown) by an inert gas. Then, the raw material is introduced into the vaporizer VPR through the valve VV1, the liquid flow rate controller MC1, and the valve VV2 in this order. The flow rate of the raw material introduced into the vaporizer VPR is adjusted to a desired flow rate by the liquid flow rate controller MC1. The inert gas used for pumping the raw material is, for example, He, Ar, Ne, Xe, or N ₂ .

  The raw material is vaporized by being depressurized and heated in the vaporizer VPR. The vaporized source gas is supplied into the chamber CMB via the valve VV4 and the pipe PP1. The pipe PP1 is heated by, for example, a heater (not shown). Thereby, reliquefaction of the vaporized source gas is suppressed.

  Further, in the vaporizer VPR, the flow rate of the carrier gas that is flowed to the vaporizer VPR and the vaporization temperature in the vaporizer VPR are controlled so as to be lower than the saturated vapor pressure when the raw material is vaporized. Thereby, even if each boiling point and saturated vapor pressure differ among two or more types of organic siloxane raw materials, these raw materials can be vaporized evenly. Therefore, vaporized gas can be obtained while maintaining the mixing ratio in the raw material reservoir tank TNK.

The carrier gas pipe (not shown) is connected to the vaporizer VPR via the gas flow rate controller MC2 and the valve VV3. In the vaporizer VPR, the carrier gas transports the source gas into the chamber CMB via the valve VV4 and the pipe PP1. The flow rate of the carrier gas is adjusted to a desired flow rate by the gas flow rate controller MC2. The carrier gas is, for example, He, Ar, Ne, Xe, N ₂ or the like.

In the first embodiment, a pipe for oxidizing gas (not shown) is connected to the chamber CMB via the gas flow rate controller MC3 and the valve VV5. Thereby, in addition to source gas and carrier gas, oxidizing gas can be supplied to chamber CMB. The oxidant gas includes at least one of O ₂ , CO ₂ , CO, N ₂ O, and NO ₂ . In other words, the oxidant gas is, for example, O ₂ , CO ₂ , CO, N ₂ O, NO ₂ , or a mixed gas thereof.

  A shower head SH having a plurality of through holes is provided in the chamber CMB. Thereby, the source gas, the carrier gas, and the oxidant gas introduced into the chamber CMB are dispersed by the shower head SH.

  A high frequency power supply RF is connected to the shower head SH via a feeder (not shown) and a matching controller MTC. Thereby, high frequency power is supplied between the shower head SH and the stage STG. The high frequency power supply RF may be connected to the stage STG side. As used herein, “high frequency” refers to a frequency of 1 MHz or higher. Specifically, the high frequency is 13.56 MHz or this multiplied wave. In addition to the high frequency power source RF, a low frequency power source (not shown) may be connected. The low frequency power source is connected to either the shower head SH or the stage STG.

  The source gas, carrier gas and oxidant gas are introduced into the chamber CMB via the pipe PP1. These gases are turned into plasma by an applied voltage applied between the shower head SH and the stage STG. Thereby, a porous insulating film (PF1 or PF2 to be described later) can be formed on the semiconductor substrate SUB placed on the stage STG.

Note that a gas such as nitrogen trifluoride (NF ₃ ), sulfur hexafluoride (SF ₆ ), tetrafluoromethane (CF ₄ ), hexafluoroethane (C ₂ F ₆ ), or the like is used for cleaning the chamber CMB. Can do. These gases may be used as a mixed gas with oxygen, ozone or the like, if necessary.

(Organic siloxane raw material)
Next, the organic siloxane raw material used in the first embodiment will be described. In the first embodiment, two or more types of organosiloxane raw materials each having a cyclic SiO structure as a main skeleton and having different structures are used. Hereinafter, the cyclic SiO structure of the main skeleton is referred to as “cyclic siloxane skeleton”.

  The organic siloxane raw material has a cyclic organic silica skeleton represented by the following chemical formula (1).

・・・・（１）

(1)

  However, in Chemical formula (1), n is 2-5, Rx and Ry are either hydrogen, an unsaturated hydrocarbon group, and a saturated hydrocarbon group, respectively, of unsaturated hydrocarbon group and saturated hydrocarbon group Each is any of a vinyl group, an allyl group, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and a tertiary butyl group.

  By using such an organic siloxane raw material, independent pores (closed pores) can be formed in the porous insulating film by the cyclic SiO structure of the raw material. Therefore, a porous insulating film having a uniform film density distribution can be formed. For example, the pore size can be controlled by changing n in the chemical formula (1). That is, the relative dielectric constant of the porous insulating film can be controlled.

  For example, n of at least two types of organosiloxane raw materials are different from each other. Of the at least two types of organic siloxane raw materials, the cyclic organic siloxane skeleton of the first organic siloxane raw material is smaller than the cyclic siloxane skeleton of the second organic siloxane raw material. In other words, the binding energy of the cyclic organic siloxane skeleton in the first organic siloxane raw material is stronger than the binding energy of the cyclic siloxane skeleton in the second organic siloxane raw material. Thereby, in the porous insulating film forming step described later, the second organic siloxane raw material having a cyclic siloxane skeleton having a low binding energy is preferentially dissociated. At this time, a part of the dissociated Si—O bond bonds the first organosiloxane raw materials to each other. That is, the first organosiloxane raw material can form a strong network through Si—O bonds. Therefore, the film strength of the porous insulating film can be improved.

  For example, n is 3 among at least one kind of organosiloxane raw material. In other words, at least one kind of organic siloxane raw material includes a 6-membered cyclic organic siloxane skeleton. Thereby, a porous insulating film having an average pore diameter of 1 nm or less can be formed.

  Further, among at least two kinds of organosiloxane raw materials, one n is preferably 3, and the other n is preferably 4. In other words, one of the at least two types of organic siloxane raw materials (the first organic siloxane raw material described above) includes a 6-membered cyclic organic siloxane skeleton. The other (the second organic siloxane raw material described above) contains an 8-membered cyclic siloxane skeleton. Thereby, the film | membrane intensity | strength of a porous insulating film can be improved with the above-mentioned mechanism rather than the case where a single organosiloxane raw material is used. In addition, an organic siloxane raw material in which n is 3 or 4 is particularly preferable because it is easy to produce and many are chemically stable. Moreover, since the raw material which performed such mixing has a high polymerization temperature compared with a single raw material, it is stable with respect to heat.

  Further, for example, at least one kind of organosiloxane raw material has an unsaturated hydrocarbon group. In the chemical formula (1), Rx or Ry is an unsaturated hydrocarbon group. In this case, in the porous insulating film forming step, the unsaturated hydrocarbon group is opened in the plasma, and the polymerization reaction proceeds between the molecules of the organic siloxane raw material. Thereby, a crosslinked structure can be easily formed between the molecules of the organic siloxane raw material.

  In the chemical formula (1), it is preferable that Rx and Ry use at least one straight-chain unsaturated hydrocarbon group having 2 to 4 carbon atoms or a branched saturated hydrocarbon group having 3 to 4 carbon atoms.

  Specifically, for example, a trivinylcyclotrisiloxane derivative represented by the following chemical formula (2) or a tetravinylcyclotetrasiloxane derivative represented by the following chemical formula (3) is exemplified.

・・・・（２）

(2)

・・・・（３）

.... (3)

However, in the chemical formula (2) or (3), R ₁ , R ₂ , R ₃ and R ₄ are any one of hydrogen, an unsaturated hydrocarbon group and a saturated hydrocarbon group. Each of the unsaturated hydrocarbon group and the saturated hydrocarbon group is any one of a vinyl group, an allyl group, a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group.

(Semiconductor device)
Next, the overall structure of the semiconductor device SD according to the first embodiment will be described with reference to FIG. FIG. 2 is a cross-sectional view showing the configuration of the semiconductor device SD according to the first embodiment. The semiconductor device SD of the first embodiment includes a porous insulating film (PF1 or PF2). Here, for example, a plurality of porous insulating films (porous insulating film PF1 and porous insulating film PF2) are stacked.

  For example, the porous insulating film PF1 is provided on a substrate (not shown). Any member that can mechanically support the porous insulating film PF1 may be used. The substrate is, for example, a semiconductor substrate. Specifically, the substrate is a silicon substrate.

In addition, the substrate may be a metal substrate, an insulating substrate, or a composite material thereof. Specifically, the metal substrate is, for example, Au, Cu, Ti, Fe or an alloy containing them. The insulating substrate may be glass (SiO ₂ ), polymer resin, plastic, silicon resin, or a composite material thereof. The substrate may be composed of a semiconductor substrate and an insulating substrate. Specifically, an SOI (Silicon On Insulator) substrate can be used. In addition, the porous insulating film PF1 itself may form a substrate.

  For example, a plurality of wirings IC1 are provided in the porous insulating film PF1. Wiring IC1 contains Cu as a main component, for example. The wiring IC1 may contain a metal element other than Cu. In addition, the wiring IC1 may be W, Al, or an alloy thereof.

  A barrier metal BM1 is provided on the side surface and the bottom surface of the wiring IC1. When the wiring IC1 includes Cu, the barrier metal BM1 is formed of, for example, Ti, Ta, W, Ru, or a nitride or carbonitride thereof.

  A barrier insulating film IF1 is provided on the porous insulating film PF1. The barrier insulating film IF1 has a function of preventing Cu oxidation and diffusion of Cu into the insulating film, and a function as an etching stop layer when the porous insulating film PF1 and the like are processed. The barrier insulating film IF1 is, for example, a SiC film, a SiCN film, a SiN film, a BN film, or a BCN film. Note that the barrier insulating film IF1 may be omitted.

  Further, a metal cap layer (not shown) may be provided on the wiring IC1. The metal cap layer may be formed of, for example, CoWP, CoWB, CoSnP, CoSnB, NiB, or NiMoB.

  A porous insulating film PF2 is provided on the barrier insulating film IF1. For example, the porous insulating film PF2 is formed in the same manner as the above-described porous insulating film PF1.

  In the porous insulating film PF2, a via VA and a wiring IC2 are provided by, for example, a dual damascene method. The wiring IC2 is connected to the wiring IC1 located in the lower layer through the via VA. The via VA and the wiring IC2 are made of the same material as that of the wiring IC1, for example. A wiring or a via may be formed of a different metal in each wiring layer.

  Further, a barrier metal BM2 is provided on the side and bottom surfaces of the via VA and the side and bottom surfaces of the wiring IC2. Barrier metal BM2 is formed of the same material as barrier metal BM1, for example.

  A barrier insulating film IF2 is provided on the porous insulating film PF2. Barrier insulating film IF2 is formed of the same material as barrier insulating film IF1, for example.

  A multilayer porous insulating film may be further formed on the barrier insulating film IF2.

(Porous insulating film and semiconductor device manufacturing method)
Next, a method for manufacturing the semiconductor device SD according to the first embodiment will be described with reference to FIGS. 3 to 6 are cross-sectional views for explaining the method for manufacturing the semiconductor device SD according to the first embodiment. Details will be described below.

  As shown in FIG. 3A, a porous insulating film PF1 is formed on a substrate (not shown). This porous insulating film PF1 is formed, for example, in the same manner as a porous insulating film PF2 described later. Next, a plurality of wiring grooves (not shown) are formed in the porous insulating film PF1. Next, the barrier metal BM1 is formed on the side surface and the bottom surface of the wiring IC1. Next, a metal film (not shown) is formed in the wiring trench. Next, the metal film is polished by CMP (Chemical Mechanical Polishing) to embed metal in the wiring trench. Thereby, the wiring IC1 is formed in the porous insulating film PF1. Next, a barrier insulating film IF1 is formed on the porous insulating film PF1.

  As shown in FIG. 3B, a porous insulating film PF2 is formed on the barrier insulating film IF1 on the barrier insulating film PF1 using an organic siloxane raw material containing hydrocarbon (porous insulating film forming step).

  In this step, two or more kinds of organic siloxane raw materials each having a cyclic SiO structure as a main skeleton and different structures are vaporized and transported together with a carrier gas to the chamber CMB. At this time, an oxidizing gas containing oxygen atoms is added. Then, the porous insulating film PF2 is formed in the chamber CMB by the plasma CVD method or the plasma polymerization method.

  When the organic siloxane raw material has a cyclic organosiloxane skeleton, the cyclic SiO structure can be introduced into the porous insulating film PF2 as pores. In the porous insulating film PF2, pores corresponding to the diameter of the annular SiO structure are formed. Therefore, it is possible to introduce pores finely and uniformly into the porous insulating film PF2.

Further, as described above, the oxidant gas contains one or more of O ₂ , CO ₂ , CO, N ₂ O, and NO ₂ . Although H ₂ O can be considered as the oxidant gas, when H ₂ O is used, Si—OH groups are formed in the porous insulating film PF2. In this case, the dielectric constant of the porous insulating film increases. Therefore, by using the above-described gas as the oxidant gas, the film formation rate can be increased without increasing the relative dielectric constant.

  In the porous insulating film forming step, the flow rate ratio of the added oxidant gas to the carrier gas flow rate is greater than 0 and 0.08 or less. When the ratio of the oxidant gas flow rate to the carrier gas flow rate is equal to or higher than the lower limit, the film formation rate can be increased as compared with the case where no oxidant gas is added. The lower limit value of the added oxidant gas flow rate ratio relative to the carrier gas flow rate is larger than the gas flow rate ratio including oxygen due to unintentional mixing in the chamber CMB (so-called contamination). Moreover, when the ratio of the oxidant gas flow rate to the carrier gas flow rate is not more than the above upper limit value, the film strength of the porous insulating film can be improved as compared with the case where there is only one kind of organic siloxane raw material. The relationship between the ratio of the oxidant gas flow rate to the carrier gas flow rate, the deposition rate and the film strength of the porous insulating film will be described in detail later.

  The carrier gas flow rate is preferably 1 to 100 times the liquid flow rate of the organosiloxane raw material. Thereby, the organic siloxane raw material can be transported to the chamber CMB without liquefying.

  The flow rate ratio of the added oxidant gas to the flow rate of the organosiloxane raw material is 0.1 or more and 5 or less. The flow rate of the organic siloxane raw material here is a gas flow rate when the organic siloxane raw material is vaporized. The number of moles of the organic siloxane raw material per unit time can be obtained from the mixing ratio in the raw material reservoir tank TNK and the liquid flow rate in the liquid flow rate controller MC1. In the same way as the ratio of the oxidant gas flow rate to the carrier gas flow rate, the ratio of the oxidant gas flow rate to the organosiloxane raw material flow rate is within the above range, thereby increasing the deposition rate of the porous insulating film and improving the film strength. Can be made.

  For example, when two kinds of organic siloxane raw materials are used, the mixing ratio of the first organic siloxane raw material and the second organic siloxane raw material is 1: 9 to 9: 1.

  In the porous insulating film forming step, the atmospheric pressure in the chamber CMB is set within a range of, for example, 1 Torr or more and 6 Torr or less by the vacuum pump VP. The partial pressure of the organic siloxane raw material gas in the chamber CMB is preferably 0.1 Torr or more and 3 Torr or less.

  Further, in the porous insulating film forming step, the substrate SUB is heated to 100 ° C. or higher and 400 ° C. or lower by heating the stage STG. Preferably, the substrate SUB is heated to 250 ° C. or higher and 400 ° C. or lower. By heating the substrate SUB to the above temperature range, the plasma polymerization reaction is promoted at the interface between the lower layer film and the porous insulating film PF2. Thereby, the adhesiveness of the porous insulating film PF2 can be improved.

Next, after the porous insulating film forming step, the porous insulating film PF2 may be irradiated with light or an electron beam having a wavelength of 400 nm or less. In the case of irradiation with an electron beam, the acceleration energy of the electron beam is preferably 1 keV or more and 30 keV or less, and the dose amount is preferably 0.05 mC / cm ² or more and 1.0 mC / cm ² or less. Moreover, when irradiating light with a wavelength of 400 nm or less, it is preferable that the irradiation time of light is 10 sec or more and 5 min or less. The light having a wavelength of 400 nm or less may be single-wavelength light having a line spectrum, broad light having broadband, or light combining these. In this step, the substrate SUB may be heated at the same time.

Next, as shown in FIG. 4A, a hard mask HM is formed on the porous insulating film PF2. The hard mask HM protects the porous insulating film PF2 in the step of forming a groove or a via hole. The hard mask HM is, for example, SiO ₂ , TEOS, or SiOC or SiOCH harder than the porous insulating film PF2 (Modulus 10 GPa or more). This hard mask HM may be omitted.

  Next, the porous insulating film PF2 is selectively removed by, for example, the RIE (Reactive Ion Etching) method. Thereby, the trench IT and the via hole VH are formed in the porous insulating film PF2. This step may be either the via first method or the trench first method.

  Next, as shown in FIG. 4B, the barrier metal BM2 is formed on the side surface and the bottom surface of the trench IT and the via hole VH. Barrier metal BM2 is formed of the same material as barrier metal BM1, for example. For example, as the barrier metal BM2, for example, Ti, Ta, W, Ru, or a nitride or carbonitride thereof is formed by sputtering.

  Next, a metal film MF is formed in the trench IT and the via hole VH by, for example, a plating method. The metal film MF is, for example, Cu.

  Next, heat treatment is performed for Cu grain growth. For example, the temperature in the heat treatment is 200 ° C. or more and 400 ° C. or less, and the heat treatment time is 30 seconds or more and 1 hour or less.

  Next, as shown in FIG. 5A, the metal film MF is polished by a CMP method to fill the trench IT and the via hole VH with metal. Thereby, the wiring IC2 and the via VA are formed in the porous insulating film PF2. At this time, the hard mask HM may be removed. Further, the surface layer of the porous insulating film PF2 may be removed.

  Next, as shown in FIG. 5B, a barrier insulating film IF2 is formed on the porous insulating film PF2. Barrier insulating film IF2 is formed of the same material as barrier insulating film IF1, for example. As the barrier insulating film IF2, for example, a SiC film, a SiCN film, a SiN film, a BN film, or a BCN film is formed.

  A plurality of porous insulating films may be further formed on the porous insulating film PF2. Through the above steps, the semiconductor device SD according to the first embodiment can be obtained.

(Example)
Next, specific examples will be described. In this example, a single porous insulating film was formed using two types of organosiloxane raw materials. In the example, the first organic siloxane raw material in which n is 3, Rx is a vinyl group, and Ry is an isopropyl group in the chemical formula (1), and the second is a compound in which n is 4, Rx is a vinyl group, and Ry is a methyl group. The organic siloxane raw material was used. The mixing ratio of the first and second organosiloxane raw materials is 4: 3.

In the porous insulating film forming step, He was used as a carrier gas. The flow rate of the carrier gas was changed in the range of 300 sccm to 2000 sccm. N ₂ O was used as the oxidant gas. The flow rate of the oxidizing gas was changed in the range of 12 sccm to 80 sccm.

  A high frequency of 13.56 MHz was used for film formation. The applied power is 25 W or more and 500 W or less. The applied power depends on the interelectrode distance and the electrode area. For this reason, the applied power can be freely adjusted by the semiconductor manufacturing apparatus SME, and is not limited to the above-described range. Similar results can be obtained even when a low frequency of 400 to 500 kHz is applied together with a high frequency of 13.56 MHz.

(Comparative example)
In the comparative example, a single layer of a porous insulating film was formed using only one type of organosiloxane raw material. In the comparative example, in the chemical formula (1), only (first) organosiloxane raw material in which n is 3, Rx is a vinyl group, and Ry is an isopropyl group was used.

(result)
Next, using FIG. 6 to FIG. 9, the effect of the first embodiment will be described together with the results of the examples.

FIG. 6 is a graph showing the relationship between the flow rate of the oxidant gas and the deposition rate of the porous insulating film in the example. FIG. 6 shows film formation rates when the flow rate of He as the carrier gas is 1000 sccm, 1600 sccm, and 1800 sccm, respectively. As shown in FIG. 6, as the flow rate of the oxidant gas N ₂ O is increased, the deposition rate of the porous insulating film is increased. Here, also for the oxidant gas other than N 2 _O, it shows a similar trend.

FIG. 7 is a graph showing the relationship between the flow rate of the carrier gas and the deposition rate of the porous insulating film in the example. FIG. 7 shows the film formation rate when the flow rate of the oxidant gas N ₂ O is 0 sccm (no addition), 15 sccm, and 30 sccm. As shown in FIG. 7, the deposition rate of the porous insulating film decreases as the flow rate of He as the carrier gas is increased. This is because the organic siloxane raw material is diluted by the carrier gas.

FIG. 8 is a diagram showing the relationship between the ratio of the oxidant gas flow rate to the carrier gas flow rate and the deposition rate of the porous insulating film. The horizontal axis in FIG. 8 indicates the flow rate ratio (N ₂ O / He) of the oxidant gas (N ₂ O) to the carrier gas (He). In FIG. 8, the comparative example is also plotted.

As shown in FIG. 8, in the comparative example and the example, as the ratio of the oxidant gas flow rate to the carrier gas flow rate increases, the deposition rate of the porous insulating film increases. In FIG. 8, the slope of the example is steeper than that of the comparative example. In the examples, it is shown that there is an effect of increasing the film formation rate with respect to the addition of N ₂ O.

  The tendency regarding the film forming speed in FIG. 8 is the same even when the ratio of the first organic siloxane raw material with n of 3 to the second organic siloxane raw material with n of 4 is a ratio other than 4: 3. . When the ratio of the first and second organosiloxane raw materials is 4: 3, the gradient of the film formation rate with respect to the ratio of the oxidant gas flow rate to the carrier gas flow rate is the largest.

  The tendency is not limited to the case where the first organic siloxane raw material having n of 3 and the second organic siloxane raw material having n of 4 are mixed. That is, even when other organic siloxane raw materials are combined, the same tendency as in FIG. 8 is exhibited by mixing two or more types of organic siloxane raw materials having different structures and an oxidizing gas.

  Thus, in the first embodiment, an oxidant gas is added to a single organic siloxane raw material as in the comparative example by adding an oxidant gas to two or more types of organic siloxane raw materials having different structures. The deposition rate of the porous insulating film can be increased as compared with the case.

  FIG. 9 is a diagram showing the relationship between the ratio of the oxidant gas flow rate to the carrier gas flow rate and the film strength of the porous insulating film. The horizontal axis in FIG. 9 is the same as that in FIG. The vertical axis | shaft of FIG. 9 is the film | membrane intensity | strength (Modulus) measured by the nanoinduction method. In FIG. 9, the comparative example is also plotted.

  As shown in FIG. 9, in the comparative example and the example, the film strength of the porous insulating film decreases as the ratio of the oxidant gas flow rate to the carrier gas flow rate increases. That is, the film strength of the porous film is in a trade-off relationship with the film formation speed.

  On the other hand, regardless of the ratio of the oxidant gas flow rate to the carrier gas flow rate, the film strength of the example using two types of organosiloxane raw materials is higher than the film strength of the comparative example using only a single organic siloxane raw material. . In particular, in the region where the ratio of the oxidant gas flow rate to the carrier gas flow rate is low, the film strength of the example is higher than the film strength of the comparative example. Specifically, when the ratio of the oxidizing gas flow rate to the carrier gas flow rate is 0.08 or less, the film strength in the example is higher than that in the comparative example. When the ratio of the oxidant gas flow rate to the carrier gas flow rate is greater than 0.08, the film strength in the example is equivalent to that in the comparative example.

  Further, when the ratio of the oxidant gas flow rate to the carrier gas flow rate is 0.04 or less, the film strength in the example shows a significantly higher value than that in the comparative example even when measurement error is taken into consideration.

  The tendency regarding the film strength in FIG. 9 is the same even when the ratio of the first organic siloxane raw material having n of 3 to the second organic siloxane raw material having n of 4 is other than 4: 3. Note that when the ratio of the first and second organosiloxane raw materials is 4: 3, the film strength of the porous insulating film is highest.

  The tendency is not limited to the case where the first organic siloxane raw material having n of 3 and the second organic siloxane raw material having n of 4 are mixed. That is, even when other organic siloxane raw materials are combined, the same tendency as in FIG. 9 is exhibited by mixing two or more types of organic siloxane raw materials having different structures and an oxidizing gas.

  Thus, in the first embodiment, an oxidant gas is added to a single organic siloxane raw material as in the comparative example by adding an oxidant gas to two or more types of organic siloxane raw materials having different structures. The film strength of the porous insulating film can be increased as compared with the case.

  From the results of FIGS. 8 and 9 described above, in the first embodiment, the ratio of the oxidant gas flow rate to the carrier gas flow rate is preferably greater than 0 and 0.08 or less. Further, the ratio of the oxidant gas flow rate to the carrier gas flow rate is more preferably 0.005 or more and 0.04 or less.

  As described with reference to FIG. 8, because the ratio of the oxidant gas flow rate to the carrier gas flow rate is greater than 0 (that is, by adding the oxidant gas), the film formation rate is higher than when no oxidant gas is added. can do.

  Further, the ratio of the oxidant gas flow rate to the carrier gas flow rate is preferably in a range larger than the contamination to the chamber CMB. From such a viewpoint, the ratio of the oxidant gas flow rate to the carrier gas flow rate is preferably 0.005 or more. Thereby, in the range beyond the control precision of gas flow controller MC3, the film-forming speed | rate can be improved stably.

  As described with reference to FIG. 9, when the ratio of the oxidant gas flow rate to the carrier gas flow rate is 0.08 or less, the film strength of the porous insulating film is improved as compared with the case where there is only one kind of organosiloxane raw material. be able to.

  In FIG. 9, as described above, when the ratio of the oxidant gas flow rate to the carrier gas flow rate is 0.04 or less, the film strength in the example is a value significantly higher than that of the comparative example even when measurement error is taken into consideration. Indicates. In addition, considering the in-plane distribution of the porous insulating film, the gas distribution in the manufacturing process, the process margin, the variation between batches, etc., the ratio of the oxidant gas flow rate to the carrier gas flow rate is 0.04 or less, A porous insulating film having a high film strength can be obtained stably.

(Function and effect)
Next, the function and effect of the first embodiment will be described together with the mechanism. First, the effects of using two or more kinds of organic siloxane raw materials having different structures are as follows.

  For example, when two kinds of first and second organic siloxane raw materials are used, the second organic siloxane raw material having a cyclic siloxane skeleton having a low binding energy is preferentially dissociated. At this time, a part of the dissociated Si—O bond bonds the first organosiloxane raw materials to each other. That is, the first organosiloxane raw material can form a strong network through Si—O bonds. Therefore, the film strength of the porous insulating film can be improved.

  Next, the following effects can be considered by adding an oxidizing gas in addition to two or more kinds of organic siloxane raw materials.

  By adding an oxidant gas while two or more types of organosiloxane raw materials are in a plasma state, the mean free path of electrons in the plasma is reduced and the ion energy is reduced. This is because molecules of the oxidant gas become a steric barrier. For this reason, in the first embodiment, the dissociation efficiency of the second organosiloxane raw material having a low binding energy is reduced as compared with the case where no oxidant gas is added. Accordingly, it is difficult to form a crosslinked structure of the first organic siloxane raw material by Si—O bonds.

  In addition, the oxidant gas extracts part of the side chain carbon and hydrogen atoms from the organosiloxane raw material. For this reason, many active binding species are formed in the side chain. Such active bond species promote bonds between hydrocarbons. In particular, in the case of having an unsaturated hydrocarbon group, the bond between hydrocarbons is promoted by the cleavage of the unsaturated hydrocarbon group. Therefore, in the porous insulating film formed by adding the oxidant gas, the crosslinked structure via the hydrocarbon is dominant.

  Thus, the addition of the oxidant gas increases the cross-linked structure through hydrocarbons in the porous insulating film. Thereby, the film-forming speed can be increased. However, as the cross-linking structure via hydrocarbons increases, the film strength of the porous insulating film is greater than the case where the cross-linking structure of the first organosiloxane raw material via the Si-O bond is dominant. It gets lower. Therefore, there exists an optimum range for achieving both film formation speed and film strength in the ratio of the oxidant gas flow rate to the carrier gas flow rate.

  As described above, according to the first embodiment, two or more kinds of organic siloxane raw materials each having a cyclic SiO structure as a main skeleton and having different structures are mixed with an oxidant gas containing oxygen atoms to obtain a porous material. An insulating film is formed. At this time, the ratio of the added oxidant gas flow rate to the carrier gas flow rate is greater than 0 and 0.08 or less. Thereby, the film formation rate of the porous insulating film can be increased and the film strength of the porous insulating film can be improved.

  In the first embodiment, the case where the wiring or via is formed in the porous insulating film as the interlayer insulating film of the semiconductor device SD has been described. However, the present invention is not limited to this case. The porous insulating film may be used for things other than the semiconductor device SD, and may be a single layer film.

(Second Embodiment)
10 and 11 are diagrams for explaining the characteristics of the porous insulating film according to the second embodiment. The second embodiment is the same as the first embodiment except that the conditions for forming the porous insulating film are further optimized than those of the first embodiment. Details will be described below.

  The inventors produced porous insulating films using various organosiloxane raw materials in the manufacturing method according to the first embodiment. The film formation speed and film strength were significantly high under specific optimum conditions. I found out. As will be described later, the optimum condition was found to correlate with “the average number of carbon atoms per mole of the mixed raw material of the organosiloxane raw material”.

According to the second embodiment, in the mixed raw material of two or more kinds of the organic siloxane raw materials, the average carbon number per mole of the mixed raw material of the organic siloxane raw material is 15 or more. The peak area ratio of the peak of CHx wavenumber 2900 cm ^-1 vicinity against -Si-O-Si- peak at a wavenumber of 1100 cm ^-1 vicinity as determined by FTIR method of the porous insulating film is 0.23 or more. Details will be described below.

  FIG. 10 shows spectra measured by the Fourier transform infrared spectroscopy (FTIR) method for the porous insulating films of the second embodiment and the comparative example. The second embodiment in the figure is a porous insulating film produced under the optimum conditions among the conditions of the first embodiment. Further, the comparative example in the figure is a porous insulating film produced under other conditions different from the optimum conditions among the conditions of the first embodiment. The comparative example described in FIGS. 10 and 11 is different from the comparative examples in FIGS.

  Specifically, in the second embodiment (optimum conditions), in the chemical formula (1), n is 3, Rx is a vinyl group, Ry is an isopropyl group, n is 4, Rx And a second organosiloxane raw material in which Ry is an isopropyl group. In the comparative example (other conditions), at least one of the organosiloxane raw materials having a small number of carbon atoms in the side chain was used.

As shown in FIG. 10, for any porous insulating film, a Si—O—Si bond peak appears in the vicinity of a wave number of 1100 cm ⁻¹ . Further, a CHx peak appears in the vicinity of a wave number of 2900 cm ⁻¹ . This CHx peak is caused by the portion of the hydrocarbon in the porous insulating film that remains without dissociation of the side chain of the organic siloxane raw material. As shown in the figure, the CHx peak of the porous insulating film manufactured under the optimum conditions is higher than the CHx peak of the porous insulating film manufactured under other conditions.

  FIG. 11 shows the relationship between the average number of carbon atoms per mole of the organic siloxane raw material and the CHx / Si—O—Si ratio. The horizontal axis in FIG. 11 indicates the average number of carbon atoms per mole of the organic siloxane raw material. Since two or more kinds of organic siloxane raw materials are used, the average carbon number is a value obtained by multiplying the number of carbons present in each organic siloxane raw material by a mixing ratio.

The vertical axis in FIG. 11 indicates “CHx / −Si—O—Si—ratio”. This "CHx / -Si-O-Si-ratio" means -Si-O- in the vicinity of wave number 1100 cm ^-1 in the spectrum after removing the background from the spectrum detected by FTIR as shown in FIG. It is the peak area ratio of the CHx peak in the vicinity of a wave number of 2900 cm ⁻¹ to the Si− peak. "CHx / -Si-O-Si-ratio" correlates with the abundance ratio of CHx with respect to -Si-O-Si- bonds in the porous insulating film.

  In FIG. 11, the second embodiment (optimum condition) is indicated by a white circle, and the comparative example (other conditions) is indicated by a black square. As shown in FIG. 11, in the second embodiment (optimum condition), the average number of carbon atoms per mole of the organic siloxane raw material is 15 or more, and the “CHx / —Si—O—Si ratio” is 0. It was 23 or more. As described above, in the second embodiment (optimum condition), a large amount of CHx is taken into the porous insulating film due to the side chain of the organic siloxane raw material.

  In the second embodiment, the porous insulating film produced under the optimum conditions has the following characteristics based on the raw materials used. It includes Si, O, C, and H, a cyclic SiO structure, and unsaturated and branched hydrocarbon groups bonded to Si. In addition, as described above, the “CHx / —Si—O—Si— ratio” is 0.23 or more. For example, the unsaturated hydrocarbon group contained in the porous insulating film is a vinyl group, and the branched hydrocarbon group is an isopropyl group.

  Next, the function and effect of the second embodiment will be described. In the second embodiment (optimum conditions), it is considered that the film forming speed and the film strength are remarkably increased due to the following effects. As described above, for example, when two types of the first and second organic siloxane raw materials are used, the second organic siloxane raw material having a cyclic siloxane skeleton having a low binding energy is preferentially dissociated to form the first organic Bond siloxane raw materials together. Thereby, the film strength of the porous insulating film is improved.

  On the other hand, the phenomenon in which the cyclic siloxane skeleton is dissociated also depends on the side chain of the organic siloxane raw material. In 2nd Embodiment (optimum conditions), the average carbon number per mol is 15 or more among two or more types of organic siloxane raw materials. That is, in the second embodiment, the number of carbons contained in the side chain is large. This reduces the probability that the side chain dissociates in the plasma.

  On the other hand, in the second embodiment, the probability that the cyclic siloxane skeleton of the second organic siloxane raw material is dissociated is higher than that of the side chain. Thereby, in the second embodiment, many side chains of the organic siloxane raw material remain. Therefore, in FIG. 11, the porous insulating film manufactured under the optimum conditions as in the second embodiment is more “CHx / −Si—O—Si—ratio” than the porous insulating film manufactured under other conditions. It is thought that was high.

  By the mechanism as described above, according to the second embodiment, it is possible to further increase the film forming speed of the porous insulating film and improve the film strength of the porous insulating film as compared with the first embodiment. it can.

(Third embodiment)
The 1st and 2nd cyclic organosiloxane shown by Chemical formula (1) was used. Among these, as the first cyclic organosiloxane, R1 (Rx) is a vinyl group, R2 (Ry) is an isopropyl group, and n = 3 (2,4,6-triisopropyl-2,4,6) -Trivinylcyclotrisiloxane). As the second cyclic organosiloxane, R1 (Rx) is a vinyl group, R2 (Ry) is an isopropyl group, and n = 4 (2,4,6,8-tetraisopropyl-2 , 4,6,8-tetravinylcyclotrisiloxane). He was used as the carrier gas, and N ₂ O was used as the oxidant. The flow rate of the oxidant was set to 0.06 with respect to the carrier gas flow rate.

  FIG. 20 is a graph showing changes in the k value when the mixing concentration of the second cyclic siloxane raw material is used as a variable. From this result, it can be seen that the second cyclic siloxane concentration is the lowest k value in the vicinity of 20 to 45% (first cyclic organic siloxane raw material: 1 vs. second cyclic organic siloxane raw material: 3/4). found.

  FIG. 21 is a graph showing changes in the film formation rate when the mixing concentration of the second cyclic siloxane raw material is used as a variable. From this result, it was found that when the second cyclic siloxane concentration was 43%, the film formation rate showed the maximum value, and even if the concentration was higher than that, it did not change.

  FIG. 22 is a graph showing changes in film strength when the mixing concentration of the second cyclic siloxane raw material is used as a variable. From this result, it was found that the second cyclic siloxane concentration was 43% and showed the maximum value, and even if the concentration was higher than that, it did not change.

(Fourth embodiment)
FIG. 12 is a cross-sectional view showing a configuration of a semiconductor device SD according to the fourth embodiment. The fourth embodiment is the same as the first embodiment except that the multilayer wiring layer is formed by a single damascene method. Details will be described below.

  As shown in FIG. 12, a porous insulating film PF2 is provided on the barrier insulating film IF1. Via VA is provided in porous insulating film PF2, for example, by a single damascene method. A barrier metal BM2 is provided on the side surface and the bottom surface of the via VA.

  A barrier insulating film IF2 is provided on the porous insulating film PF2. A porous insulating film PF3 is provided on the barrier insulating layer IF2. In the porous insulating film PF3, a wiring IC3 is provided by, for example, a single damascene method. A barrier metal BM3 is provided on the side surface and the bottom surface of the wiring IC3. The wiring IC3 is connected to the wiring IC1 located in the lower layer through the via VA.

  Next, a method for manufacturing the semiconductor device SD according to the third embodiment will be described with reference to FIGS. 13 to 16 are cross-sectional views for explaining the method for manufacturing the semiconductor device SD according to the third embodiment. The manufacturing method of the semiconductor device SD according to the third embodiment is the same as that of the first embodiment except that it is a single damascene method.

  As shown in FIG. 13A, a porous insulating film PF1 having a wiring IC1 is formed on a substrate (not shown). Next, a barrier insulating film IF1 is formed on the porous insulating film PF1.

  Next, as shown in FIG. 13B, a porous insulating film PF2 is formed on the barrier insulating film IF1 using an organic siloxane raw material containing hydrocarbon. Next, although not shown, a hard mask HM is formed on the porous insulating film PF2.

  Next, as shown in FIG. 14A, the porous insulating film PF2 is selectively removed by, eg, RIE. Thereby, a via hole VH is formed in the porous insulating film PF2.

  Next, as shown in FIG. 14B, the barrier metal BM2 is formed on the side surface and the bottom surface of the via hole VH. Next, a metal film MF is formed in the via hole VH. Next, heat treatment is performed for Cu grain growth.

  Next, the metal film MF is polished by CMP to fill the via hole VH with metal. Thereby, a via VA is formed in the porous insulating film PF2. At this time, the hard mask HM may be removed. Further, the surface layer of the porous insulating film PF2 may be removed.

  Next, as shown in FIG. 15A, a barrier insulating film IF2 is formed on the porous insulating film PF2. Next, a porous insulating film PF3 is formed on the barrier insulating film IF2 in the same manner as the porous insulating film PF2.

  Next, as shown in FIG. 15B, the porous insulating film PF3 is selectively removed by, eg, RIE. Thereby, the trench IT is formed in the porous insulating film PF3.

  Next, as shown in FIG. 16, the barrier metal BM3 is formed on the side surface and the bottom surface of the trench IT. Next, a metal film MF is formed in the trench IT. Next, heat treatment is performed for Cu grain growth.

  Next, the metal film MF is polished by CMP to fill the trench IT with metal. Thereby, the wiring IC3 is formed in the porous insulating film PF2. Next, a barrier insulating film IF3 is formed on the porous insulating film PF2.

  According to the fourth embodiment, the same effect as that of the first embodiment can be obtained. As in the second embodiment, a single damascene method may be used.

(Fifth embodiment)
FIG. 17 is a cross-sectional view showing a configuration of a semiconductor device SD according to the fifth embodiment. The fifth embodiment is the same as the first embodiment except that the transistor TR and the like are formed on the substrate SUB. Details will be described below.

  As shown in FIG. 17, an element isolation region DIR having an opening is formed in the substrate SUB. The substrate SUB is a semiconductor substrate, for example. Specifically, the substrate SUB is a silicon substrate.

  A transistor TR is formed in the opening of the element isolation region DIR. The transistor TR includes, for example, a source region, a drain region and an extension region into which impurities have been implanted, a gate insulating film formed on the substrate SUB, and a gate electrode formed on the gate insulating film (not shown above). (Illustrated).

  A passive element PD may be provided on the element isolation region DIR. The passive element PD is a resistance element formed of, for example, polysilicon.

  A multilayer wiring layer is formed on the substrate SUB and the element isolation region DIR. The multilayer wiring layer includes at least one porous insulating film similar to that of the first embodiment.

  The multilayer wiring layer includes a local wiring layer LL and a global wiring layer GL. The local wiring layer LL is a wiring layer for forming a circuit, and the global wiring layer GL is a wiring layer for routing power supply wiring and ground wiring. The uppermost layer of the global wiring layer GL is, for example, an Al wiring layer. This wiring layer includes electrode pads. A wiring layer forming the local wiring layer LL and a part of the global wiring layer GL are formed by a damascene method.

  Here, for example, the second to upper interlayer insulating layers in the local wiring layer LL are all porous insulating films similar to those in the first embodiment. Further, for example, the interlayer insulating layer excluding the uppermost wiring layer in the global wiring layer GL is the same porous insulating film as the first. Note that all interlayer insulating layers may be porous insulating films.

  The manufacturing method of the semiconductor device SD according to the fifth embodiment is the same as that of the first embodiment except that the transistor TR and the like are formed on the substrate SUB.

  For example, the element isolation region DIR having an opening (not shown) is formed on the substrate SUB by STI (Shallow Trench Isolation). Note that the element isolation region DIR may be formed by a LOCOS (Local Oxidation of Silicon) method.

  Next, a gate insulating layer and a gate electrode are formed over the substrate SUB. At this time, the passive element PD is simultaneously formed on the element isolation region DIR.

  Next, extension regions are formed by ion-implanting impurities into the substrate SUB using the gate insulating layer and the gate electrode as a mask. Next, a sidewall insulating film is formed on the sidewalls of the gate insulating layer and the gate electrode. Next, by using these as a mask, impurities are ion-implanted into the substrate SUB to form a source region and a drain region. Through the above steps, the transistor TR is formed.

  Next, a multilayer wiring layer is formed on the substrate SUB and the element isolation region DIR. The porous insulating film of the first embodiment is formed as at least one interlayer insulating layer among the multilayer wiring layers.

  According to the fifth embodiment, the same effects as those of the first embodiment can be obtained. As in the fourth embodiment, a semiconductor element such as the transistor TR may be formed on the substrate SUB.

(Sixth embodiment)
FIG. 18 is a cross-sectional view showing the configuration of the semiconductor device according to the fifth embodiment. The sixth embodiment is the same as the first embodiment except that the transistor TR and the like are formed on the substrate SUB. Details will be described below.

  FIG. 18 is a cross-sectional view of an embedded MRAM (Magnetic Random Access Memory). In the semiconductor device of FIG. 18, an MTJ element (Magnetic Tunnel Junction) 100 (FIG. 18A) and a logic circuit (FIG. 18B) are mixedly mounted.

  The MRAM determines 0 or 1 according to the magnetization direction of the magnetic material, and operates as a memory element. In general, there are two modes for reversing the magnetization of a magnetic material, inversion nucleation and domain wall motion, which can be applied to either type. In this embodiment, a domain wall motion type element will be described as an example.

  As shown in FIG. 18A, porous insulating films 160, 170, 180, and 190 are stacked in this order on the substrate SUB. The embedded MRAM has an MTJ element 100. The MTJ element 100 has a structure in which the spin absorption layers 112 and 114, the domain wall motion layer 120, the tunnel barrier layer 130, and the pinned layer 140 are stacked in this order. The lower surfaces of the spin absorption layers 112 and 114 are connected to the diffusion layers via contacts 152 and 154, respectively. The contacts 152 and 154 are embedded in the porous insulating film 160. The spin absorption layers 112 and 114 are embedded in the porous insulating film 170. The domain wall motion layer 120, the tunnel barrier layer 130, and the pinned layer 140 are embedded in the porous insulating film 180. The wiring 111 is formed on the porous insulating film 180. The upper surface of the pinned layer 140 is not covered with the porous insulating film 180 and is connected to the wiring 111. A via 115 and a wiring 116 are formed on the wiring 111. The via 115 and the wiring 116 are embedded in the porous insulating film 190.

  Note that, as illustrated in FIG. 18B, a transistor that forms a logic circuit is formed in the logic region. FIG. 18B shows the source / drain region 117 of the transistor.

  As the porous insulating films 160, 170, 180, and 190 of the embedded MRAM shown in FIG. 18, for each of the device to which the porous insulating film of the above-described embodiment is applied and the device to which the porous insulating film of the comparative example is applied, The hysteresis characteristics of the antiferromagnetic layer were investigated. Here, in the comparative example, a porous insulating film into which pores were introduced by using a porogen and a curing process was used as the porous insulating films 160, 170, 180, and 190.

  In this embodiment, the film forming temperature is 350 ° C. On the other hand, the film formation temperature is 350 ° C. in the comparative example, but 400 ° C. is also heated during the curing process.

  FIG. 19 shows hysteresis characteristics. FIG. 19A shows the result of the embodiment, and FIG. 19B shows the result of the comparative example. The horizontal axis in FIG. 19 is the magnetic field (magnetic field), and the vertical axis is the resistance ratio. In this embodiment, since the memory window is held (binary values can be obtained within a certain range (memory window)), the device can operate as a device. On the other hand, when the porous insulating film of the comparative example is applied, a memory window is not seen and it is difficult to take a binary value. That is, it was found that the comparative example does not operate as a device.

  In this embodiment, since the curing process is not performed, the process temperature can be set to 350 ° C. or lower. However, in the comparative example, a thermal history of 400 ° C. is passed due to the curing process. When heat treatment at 400 ° C. or higher is applied to the MTJ element, the following phenomenon is expected to occur. One is that the crystal structure of the antiferromagnetic layer (for example, the spin absorption layers 112 and 114, the domain wall motion layer 120, and the pinned layer 140) is changed by the heat treatment, so that the magnetization direction of the antiferromagnetic layer is changed and the pinned layer is changed. The magnetization direction cannot be fixed. The other is that metal diffusion occurs through the tunnel barrier layer 130 by the heat treatment, and the magnetization characteristics of the domain wall motion layer 120 and the pinned layer 140 change. Thus, when the porous insulating films 160, 170, 180, and 190 of the comparative example are applied, it is considered that device malfunction occurred. On the other hand, in the present embodiment, when the porous insulating films 160, 170, 180, 190 are formed, only the thermal history up to 350 ° C. is given, so that it is considered that the MTJ element 100 operates without any defects.

  When the raw material shown in the third embodiment is used, the porous insulating film can be grown at a low temperature of 350 ° C. or lower, for example, 200 ° C. By using the raw material shown in the third embodiment, the thermal load on the MTJ element 100 can be further suppressed. The growth temperature range is 350 ° C. to 25 ° C., but considering the stability of the porous insulating films 160, 170, 180, 190, the temperature is preferably 200 ° C. or higher and 350 ° C. or lower.

As described above, in this embodiment, the step of forming the porous insulating films 160, 170, 180, and 190 does not include a porogen sublimation process, and is performed at a substrate temperature of 200 ° C. or higher and 350 ° C. or lower.
Further, the semiconductor device (device) manufactured according to the present embodiment has a multilayer wiring layer including a porous insulating film, and at least one of the porous insulating films is shown in the above embodiment. It is a porous insulating film manufactured by the method. A memory element is formed in the multilayer wiring layer, and this memory element is the MTJ element 100.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

・・・・（１）
（ただし、化学式（１）において、ｎは２〜５であり、Ｒｘ及びＲｙはそれぞれ水素、不飽和炭化水素基及び飽和炭化水素基の何れかであり、前記不飽和炭化水素基および前記飽和炭化水素基の各々は、ビニル基、アリル基、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、およびターシャリーブチル基の何れかである。）
（付記５）
付記１に記載の半導体装置の製造方法において、
少なくとも二種類の前記有機シロキサン原料のうちｎは互いに異なる半導体装置の製造方法。
（付記６）
付記１に記載の半導体装置の製造方法において、
少なくとも一種類の前記有機シロキサン原料のうちｎは３である半導体装置の製造方法。
（付記７）
付記１に記載の半導体装置の製造方法において、
少なくとも二種類の前記有機シロキサン原料のうち、一方のｎは３であり、他方のｎは４である半導体装置の製造方法。
（付記８）
付記１に記載の半導体装置の製造方法において、
前記有機シロキサン原料は、不飽和炭化水素基を有する半導体装置の製造方法。
（付記９）
付記１に記載の半導体装置の製造方法において、
前記２種類以上の前記有機シロキサン原料の混合原料において、前記有機シロキサン原料の前記混合原料の１モルあたりの平均炭素数は１５以上であり、
前記多孔質絶縁膜のうちＦＴＩＲ（Ｆｏｕｒｉｅｒ Ｔｒａｎｓｆｏｒｍ Ｉｎｆｒａｒｅｄ Ｓｐｅｃｔｒｏｓｃｏｐｙ）法によって求められる波数１１００ｃｍ^−１近傍の−Ｓｉ−Ｏ−Ｓｉ−のピークに対する波数２９００ｃｍ^−１近傍のＣＨｘのピークのピーク面積比率は０．２３以上である半導体装置の製造方法。
（付記１０）
付記１に記載の半導体装置の製造方法において、
前記多孔質絶縁膜形成工程において、
前記有機シロキサン原料の流量に対する前記酸化剤ガスの流量比が０．１以上５以下である半導体装置の製造方法。
（付記１１）
付記１に記載の半導体装置の製造方法において、
前記多孔質絶縁膜形成工程において、
基板上に前記多孔質絶縁膜を形成し、当該基板を２５０℃以上４００℃以下に加熱する半導体装置の製造方法。
（付記１２）
付記１に記載の半導体装置の製造方法において、
前記多孔質絶縁膜形成工程の後に、前記多孔質絶縁膜に溝またはビアホールを形成し、金属を埋め込むことにより配線またはビアを形成する工程をさらに備える半導体装置の製造方法。
（付記１３）
Ｓｉ、Ｏ、ＣおよびＨと、環状ＳｉＯ構造と、Ｓｉに結合した不飽和炭化水素基および分枝炭化水素基と、を含む多孔質絶縁膜と、
前記多孔質絶縁膜に設けられた配線またはビアと、
を備え、
前記多孔質絶縁膜のうちＦＴＩＲ（Ｆｏｕｒｉｅｒ Ｔｒａｎｓｆｏｒｍ Ｉｎｆｒａｒｅｄ Ｓｐｅｃｔｒｏｓｃｏｐｙ）法によって求められる波数１１００ｃｍ^−１近傍の−Ｓｉ−Ｏ−Ｓｉ−のピークに対する波数２９００ｃｍ^−１近傍のＣＨｘのピークのピーク面積比率は０．２３以上である半導体装置。
（付記１４）
付記１に記載の半導体装置の製造方法において、
前記多孔質絶縁膜に含まれる前記不飽和炭化水素基はビニル基であり、
前記分枝炭化水素基はイソプロピル基である半導体装置。 In addition, the invention shown below is also disclosed by the above embodiment.
(Appendix 1)
Two or more kinds of organic siloxane raw materials each having a cyclic SiO structure as a main skeleton are vaporized, transported to a reaction furnace together with a carrier gas, and an oxidizing gas containing oxygen atoms is added. A porous insulating film forming step of forming a porous insulating film by plasma CVD (Chemical Vapor Deposition) method or plasma polymerization method at
A method of manufacturing a semiconductor device, wherein in the porous insulating film forming step, a flow rate ratio of the added oxidant gas to a carrier gas flow rate is greater than 0 and equal to or less than 0.08.
(Appendix 2)
In the method for manufacturing a semiconductor device according to attachment 1,
A method for manufacturing a semiconductor device, wherein a flow rate ratio of the oxidant gas to a flow rate of the carrier gas is 0.005 or more and 0.04 or less.
(Appendix 3)
In the method for manufacturing a semiconductor device according to attachment 1,
The method of manufacturing a semiconductor device, wherein the oxidant gas includes at least one of O ₂ , CO ₂ , CO, N ₂ O, and NO ₂ .
(Appendix 4)
In the method for manufacturing a semiconductor device according to attachment 1,
The organic siloxane raw material is a method for manufacturing a semiconductor device having a cyclic organic silica skeleton represented by the following chemical formula (1).

(1)
(In the chemical formula (1), n is 2 to 5, Rx and Ry are each hydrogen, an unsaturated hydrocarbon group or a saturated hydrocarbon group, and the unsaturated hydrocarbon group and the saturated hydrocarbon group) Each of the hydrogen groups is any one of vinyl group, allyl group, methyl group, ethyl group, propyl group, isopropyl group, butyl group, and tertiary butyl group.)
(Appendix 5)
In the method for manufacturing a semiconductor device according to attachment 1,
N is a manufacturing method of a semiconductor device in which at least two kinds of the organosiloxane raw materials are different from each other.
(Appendix 6)
In the method for manufacturing a semiconductor device according to attachment 1,
A method of manufacturing a semiconductor device, wherein n is 3 of at least one of the organosiloxane raw materials.
(Appendix 7)
In the method for manufacturing a semiconductor device according to attachment 1,
A method for producing a semiconductor device, wherein at least two of the organic siloxane raw materials have one n being 3 and the other n being 4.
(Appendix 8)
In the method for manufacturing a semiconductor device according to attachment 1,
The organic siloxane raw material is a method for manufacturing a semiconductor device having an unsaturated hydrocarbon group.
(Appendix 9)
In the method for manufacturing a semiconductor device according to attachment 1,
In the mixed raw material of the two or more kinds of the organic siloxane raw materials, the average carbon number per mole of the mixed raw material of the organic siloxane raw material is 15 or more,
The porous insulating FTIR (Fourier Transform Infrared Spectroscopy) method peak area ratio of the peak at a wavenumber of 2900 cm ^-1 vicinity of CHx against -Si-O-Si- peak at a wavenumber of 1100 cm ^-1 vicinity as determined by one of the membrane 0. A method of manufacturing a semiconductor device having 23 or more.
(Appendix 10)
In the method for manufacturing a semiconductor device according to attachment 1,
In the porous insulating film forming step,
A method for manufacturing a semiconductor device, wherein a flow rate ratio of the oxidizing gas to a flow rate of the organic siloxane raw material is 0.1 or more and 5 or less.
(Appendix 11)
In the method for manufacturing a semiconductor device according to attachment 1,
In the porous insulating film forming step,
A method for manufacturing a semiconductor device, comprising: forming the porous insulating film on a substrate; and heating the substrate to 250 ° C. or higher and 400 ° C. or lower.
(Appendix 12)
In the method for manufacturing a semiconductor device according to attachment 1,
A method for manufacturing a semiconductor device, further comprising a step of forming a wiring or a via by forming a groove or a via hole in the porous insulating film and embedding a metal after the porous insulating film forming step.
(Appendix 13)
A porous insulating film comprising Si, O, C and H, a cyclic SiO structure, and unsaturated hydrocarbon groups and branched hydrocarbon groups bonded to Si;
Wirings or vias provided in the porous insulating film;
With
The porous insulating FTIR (Fourier Transform Infrared Spectroscopy) method peak area ratio of the peak at a wavenumber of 2900 cm ^-1 vicinity of CHx against -Si-O-Si- peak at a wavenumber of 1100 cm ^-1 vicinity as determined by one of the membrane 0. 23 or more semiconductor devices.
(Appendix 14)
In the method for manufacturing a semiconductor device according to attachment 1,
The unsaturated hydrocarbon group contained in the porous insulating film is a vinyl group;
The semiconductor device, wherein the branched hydrocarbon group is an isopropyl group.

SME Semiconductor manufacturing equipment CMB Chamber SH Shower head STG Stage TNK Raw material reservoir tank VV1 Valve VV2 Valve VV3 Valve VV4 Valve VV5 Valve VV6 Exhaust valve PP1 Piping PPV Exhaust piping MC1 Liquid flow controller MC2 Gas flow controller MC3 Gas flow controller VPR Vaporizer CT Cooling Trap VP Vacuum pump MTC Matching controller RF High frequency power supply PF1 Porous insulating film PF2 Porous insulating film PF3 Porous insulating film HM Hard mask DIR Element isolation region MF Metal film IC1 Wiring IC2 Wiring IC3 Wiring VA Via BM1 Barrier metal BM2 Barrier metal BM3 Barrier metal IF1 Barrier insulating film IF2 Barrier insulating film IF3 Barrier insulating film VH Via hole IT Groove SD Semiconductor device SUB Substrate TR Transistor PD Passive element LL Local wiring layer GL Global wiring layer 100 MTJ element 111 Wiring 112 Spin absorption layer 114 Spin absorption layer 115 Via 116 Wiring 117 Source drain region 120 Domain wall displacement layer 130 Tunnel barrier layer 140 Pin layer 152 Contact 154 Contact 160 Porous insulating film 170 Porous insulating film 180 Porous insulating film 190 Porous insulating film

Claims (12)

Two or more kinds of organic siloxane raw materials each having a cyclic SiO structure as a main skeleton are vaporized, transported to a reaction furnace together with a carrier gas, and an oxidizing gas containing oxygen atoms is added. A porous insulating film forming step of forming a porous insulating film by plasma CVD (Chemical Vapor Deposition) method or plasma polymerization method at
In the porous insulating film forming step, the flow rate ratio of the added oxidant gas to the flow rate of the carrier gas is greater than 0 and 0.08 or less,
A method for manufacturing a semiconductor device, wherein a flow rate ratio of the oxidant gas to a flow rate of the carrier gas is 0.005 or more and 0.04 or less. Two or more kinds of organic siloxane raw materials each having a cyclic SiO structure as a main skeleton are vaporized, transported to a reaction furnace together with a carrier gas, and an oxidizing gas containing oxygen atoms is added. A porous insulating film forming step of forming a porous insulating film by plasma CVD (Chemical Vapor Deposition) method or plasma polymerization method at
In the porous insulating film forming step, the flow rate ratio of the added oxidant gas to the flow rate of the carrier gas is greater than 0 and 0.08 or less,
The method of manufacturing a semiconductor device, wherein the oxidant gas includes at least one of O ₂ , CO ₂ , CO, N ₂ O, and NO ₂ . Two or more kinds of organic siloxane raw materials each having a cyclic SiO structure as a main skeleton are vaporized, transported to a reaction furnace together with a carrier gas, and an oxidizing gas containing oxygen atoms is added. A porous insulating film forming step of forming a porous insulating film by plasma CVD (Chemical Vapor Deposition) method or plasma polymerization method at
In the porous insulating film forming step, the flow rate ratio of the added oxidant gas to the flow rate of the carrier gas is greater than 0 and 0.08 or less,
The organic siloxane raw material is a method for manufacturing a semiconductor device having a cyclic organic silica skeleton represented by the following chemical formula (1).

(1)
(In the chemical formula (1), n is 2 to 5, Rx and Ry are each hydrogen, an unsaturated hydrocarbon group or a saturated hydrocarbon group, and the unsaturated hydrocarbon group and the saturated hydrocarbon group) Each of the hydrogen groups is any one of vinyl group, allyl group, methyl group, ethyl group, propyl group, isopropyl group, butyl group, and tertiary butyl group.) In the manufacturing method of the semiconductor device according to claim 3,
N is a manufacturing method of a semiconductor device in which at least two kinds of the organosiloxane raw materials are different from each other. In the manufacturing method of the semiconductor device according to claim 3,
A method of manufacturing a semiconductor device, wherein n is 3 of at least one of the organosiloxane raw materials. In the manufacturing method of the semiconductor device according to claim 3,
A method for producing a semiconductor device, wherein at least two of the organic siloxane raw materials have one n being 3 and the other n being 4. Two or more kinds of organic siloxane raw materials each having a cyclic SiO structure as a main skeleton are vaporized, transported to a reaction furnace together with a carrier gas, and an oxidizing gas containing oxygen atoms is added. A porous insulating film forming step of forming a porous insulating film by plasma CVD (Chemical Vapor Deposition) method or plasma polymerization method at
In the porous insulating film forming step, the flow rate ratio of the added oxidant gas to the flow rate of the carrier gas is greater than 0 and 0.08 or less,
The organic siloxane raw material is a method for manufacturing a semiconductor device having an unsaturated hydrocarbon group. Two or more kinds of organic siloxane raw materials each having a cyclic SiO structure as a main skeleton are vaporized, transported to a reaction furnace together with a carrier gas, and an oxidizing gas containing oxygen atoms is added. A porous insulating film forming step of forming a porous insulating film by plasma CVD (Chemical Vapor Deposition) method or plasma polymerization method at
In the porous insulating film forming step, the flow rate ratio of the added oxidant gas to the flow rate of the carrier gas is greater than 0 and 0.08 or less,
In the mixed raw material of the two or more kinds of the organic siloxane raw materials, the average carbon number per mole of the mixed raw material of the organic siloxane raw material is 15 or more,
The porous insulating FTIR (Fourier Transform Infrared Spectroscopy) method peak area ratio of the peak at a wavenumber of 2900 cm ^-1 vicinity of CHx against -Si-O-Si- peak at a wavenumber of 1100 cm ^-1 vicinity as determined by one of the membrane 0. A method of manufacturing a semiconductor device having 23 or more. Two or more kinds of organic siloxane raw materials each having a cyclic SiO structure as a main skeleton are vaporized, transported to a reaction furnace together with a carrier gas, and an oxidizing gas containing oxygen atoms is added. A porous insulating film forming step of forming a porous insulating film by plasma CVD (Chemical Vapor Deposition) method or plasma polymerization method at
In the porous insulating film forming step, the flow rate ratio of the added oxidant gas to the flow rate of the carrier gas is greater than 0 and 0.08 or less,
In the porous insulating film forming step,
A method for manufacturing a semiconductor device, wherein a flow rate ratio of the oxidizing gas to a flow rate of the organic siloxane raw material is 0.1 or more and 5 or less. Two or more kinds of organic siloxane raw materials each having a cyclic SiO structure as a main skeleton are vaporized, transported to a reaction furnace together with a carrier gas, and an oxidizing gas containing oxygen atoms is added. A porous insulating film forming step of forming a porous insulating film by plasma CVD (Chemical Vapor Deposition) method or plasma polymerization method at
In the porous insulating film forming step, the flow rate ratio of the added oxidant gas to the flow rate of the carrier gas is greater than 0 and 0.08 or less,
In the porous insulating film forming step,
A method for manufacturing a semiconductor device, comprising: forming the porous insulating film on a substrate; and heating the substrate to 250 ° C. or higher and 400 ° C. or lower. Two or more kinds of organic siloxane raw materials each having a cyclic SiO structure as a main skeleton are vaporized, transported to a reaction furnace together with a carrier gas, and an oxidizing gas containing oxygen atoms is added. A porous insulating film forming step of forming a porous insulating film by plasma CVD (Chemical Vapor Deposition) method or plasma polymerization method at
In the porous insulating film forming step, the flow rate ratio of the added oxidant gas to the flow rate of the carrier gas is greater than 0 and 0.08 or less,
A method for manufacturing a semiconductor device, further comprising a step of forming a wiring or a via by forming a groove or a via hole in the porous insulating film and embedding a metal after the porous insulating film forming step. A porous insulating film comprising Si, O, C and H, a cyclic SiO structure, and unsaturated hydrocarbon groups and branched hydrocarbon groups bonded to Si;
Wirings or vias provided in the porous insulating film;
With
The porous insulating FTIR (Fourier Transform Infrared Spectroscopy) method peak area ratio of the peak at a wavenumber of 2900 cm ^-1 vicinity of CHx against -Si-O-Si- peak at a wavenumber of 1100 cm ^-1 vicinity as determined by one of the membrane 0. 23 or more,
The unsaturated hydrocarbon group contained in the porous insulating film is a vinyl group;
The semiconductor device, wherein the branched hydrocarbon group is an isopropyl group.

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