JP4257272B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a material for a low dielectric constant film, a low dielectric constant film using the same, and a semiconductor device.

  There is a demand for higher integration of semiconductor integrated circuit devices and improved processing speed. The signal propagation speed in the semiconductor integrated circuit device is limited by the wiring resistance and the parasitic capacitance between the wirings. As the semiconductor integrated circuit device is highly integrated, the wiring width and the wiring interval are reduced, the wiring resistance is increased, and the parasitic capacitance is also increased. Although the parasitic capacitance can be reduced by thinning the wiring, this increases the wiring resistance, which does not lead to an improvement in the signal propagation speed. In order to increase the signal propagation speed, it is effective to reduce the dielectric constant of the interlayer insulating film.

Conventionally, an inorganic material such as silicon dioxide (SiO ₂ ), silicon nitride (SiN), silicon oxyfluoride (SiOF), phosphosilicate glass (PSG), or an organic polymer material such as polyimide is used as an interlayer insulating film material. Has been. The relative dielectric constant of a silicon dioxide film formed by chemical vapor deposition (CVD) is about 4. The relative dielectric constant of the SiOF film is about 3.3 to 3.5, which is smaller than the relative dielectric constant of silicon dioxide. However, since SiOF has high hygroscopicity, it absorbs moisture and the relative dielectric constant tends to increase.

  As a low dielectric constant material, attention is paid to a siloxane resin containing a Si—H bond, a resin obtained by making a siloxane resin porous, and the like.

  When the siloxane resin is washed with an alkaline solution, highly hygroscopic SiOH is generated by hydrolysis. For this reason, the relative dielectric constant of the siloxane resin is increased by cleaning with an alkaline solution. On the other hand, the organic polymer film has a low glass transition temperature of about 200 to 350 ° C. and a high coefficient of thermal expansion. For this reason, the damage given to wiring is large.

  An object of the present invention is to provide a highly reliable semiconductor device having a low dielectric constant film.

According to one aspect of the invention,
A semiconductor substrate;
A first film formed on the substrate, made of a first porous silica material, and having a via hole;
A second film made of a second silica-based porous material directly formed on the first film and having a wiring groove reaching the via hole;
A semiconductor device in which the first and second silica-based porous materials are represented by the general formula of [Chemical Formula 1] or [Chemical Formula 2] described in claim 1 is provided.

According to another aspect of the invention,
Forming a first film made of a first porous silica material on a semiconductor substrate;
Forming a second film made of a second silica-based porous material directly on the first film;
Forming a groove having a depth equal to or greater than the thickness of the second film, and a via hole disposed at a position partially overlapping with the groove and penetrating the first film;
Embedding a conductive member in the via hole and the groove,
A method for manufacturing a semiconductor device is provided in which the first and second silica-based porous materials are the same as the first and second silica-based porous materials of the semiconductor device described above.

  By forming the first and second films with a silica-based porous material, the dielectric constant can be reduced. Since the etching rates of the first and second films are different, it becomes easy to selectively etch only one film.

  When a film made of a silica-based porous material with a high etching rate is laminated on a film made of a silica-based porous material with a slow etching rate, when the upper layer film is etched, the lower layer film appears. The etching can be stopped with relatively good reproducibility.

A material for forming a low dielectric constant film according to an embodiment of the present invention can be obtained by dissolving a siloxane resin and polycarbosilane in a solvent.
As a siloxane resin, for example, a general formula

で表されるものを用いることができる。ここで、Ｒ₁〜Ｒ₃は、水素、酸素もしくは１価の炭化水素基、例えばメチル基、エチル基、フェニル基等であり、Ｘは水素もしくはＳｉである。モノマ単位の繰り返し数ｎ₁は、５〜２００である。Ｒ₁〜Ｒ₃が酸素である場合には、当該酸素原子に上記Ｘと同様の基が結合する。ＸがＳｉである場合には、当該Ｓｉ原子から（−Ｓｉ−Ｏ−）骨格が延びる。上記一般式で表される樹脂として、例えば、テトラアルコキシシラン、トリアルコキシシラン、メチルトリアルコキシシラン等を原料としてゾルゲル法により生成した樹脂、もしくはこれらの混合物を原料としてゾルゲル法により生成した樹脂、テトラアルコキシシランとジメチルアルコキシシランとを原料としてゾルゲル法により生成した樹脂等が挙げられる。

Can be used. Here, R _{1 to} R ₃ are hydrogen, oxygen, or a monovalent hydrocarbon group such as a methyl group, an ethyl group, or a phenyl group, and X is hydrogen or Si. The number of monomer units n ₁ is 5 to 200. When R _{1 to} R ₃ are oxygen, the same group as X is bonded to the oxygen atom. When X is Si, a (—Si—O—) skeleton extends from the Si atom. Examples of the resin represented by the above general formula include a resin produced by a sol-gel method using tetraalkoxysilane, trialkoxysilane, methyltrialkoxysilane, or the like as a raw material, or a resin produced by a sol-gel method using a mixture thereof as a raw material, tetra Examples thereof include resins produced by sol-gel method using alkoxysilane and dimethylalkoxysilane as raw materials.

  Besides, as siloxane resin, general formula

で表される梯子型のものを用いることができる。ここで、Ｒ₄〜Ｒ₇のうち少なくとも１つは水素であり、他は、水素、フッ素もしくは１価の炭化水素基、例えばメチル基、エチル基、フェニル基等である。モノマ単位の繰り返し数ｎ₂は、５〜１００である。上記一般式で表される樹脂として、例えば水素シルセスキオキサン、メチルシルセスキオキサン、フッ素含有水素シルセスキオキサン等が挙げられる。

A ladder type represented by can be used. Here, at least one of R _{4 to} R ₇ is hydrogen, and the other is hydrogen, fluorine, or a monovalent hydrocarbon group such as a methyl group, an ethyl group, or a phenyl group. The monomer unit repeat number n ₂ is 5 to 100. Examples of the resin represented by the above general formula include hydrogen silsesquioxane, methyl silsesquioxane, fluorine-containing hydrogen silsesquioxane, and the like.

  The general formula of polycarbosilane is

で表される。ここで、Ｒ₈及びＲ₉は、水素もしくは１価の炭化水素基、例えばメチル基、エチル基、フェニル基等である。モノマ単位の繰り返し数ｍは、２０〜１，０００である。

It is represented by Here, R ₈ and R ₉ are hydrogen or a monovalent hydrocarbon group such as a methyl group, an ethyl group, or a phenyl group. The repeating number m of the monomer unit is 20 to 1,000.

  The solvent that can be used is not particularly limited as long as it dissolves the siloxane resin and polycarbosilane. Examples of usable solvents include cyclohexanone, methyl isobutyl ketone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, octane, decane, propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and the like.

  Furthermore, in order to make the low dielectric constant film porous, an organic compound (leaving agent) that is detached by heating or light irradiation may be added to the solvent. Examples of such organic compounds include adamantane compounds such as adamantane monophenol. By making it porous, the dielectric constant of the coating can be lowered. In addition, when a release agent is added too much, the mechanical strength of the coating film decreases. For this reason, it is preferable that the addition amount of the releasing agent is 70% by weight or less based on the mixture of the siloxane resin and the polycarbosilane.

  The inventors have found that when polycarbosilane is added to a siloxane resin, the property of repelling an alkaline solution is imparted. The low dielectric constant film formed using the material according to the above-described embodiment is easy to repel an alkaline solution. For this reason, even if the semiconductor substrate on which the low dielectric constant film is formed is treated with an alkaline solution, hydrolysis of the film by the alkaline solution is suppressed, and an increase in dielectric constant can be suppressed.

In addition, polycarbosilane has a high compatibility with the siloxane resin, and thus is uniformly dispersed in the siloxane resin.
Polycarbosilane also has high moisture resistance. For this reason, the remarkable effect of improving moisture resistance can be obtained by adding polycarbosilane to a porous siloxane resin having particularly poor moisture resistance.

  If the weight average molecular weight of polycarbosilane is too small, most of it will evaporate due to heating during film formation. Moreover, since the solubility with respect to a solvent will fall when a weight average molecular weight is too large, the production | generation of a coating liquid is difficult. For this reason, it is preferable that the weight average molecular weight of the polycarbosilane to be used is 1,000 or more and 500,000 or less.

  When silanol groups having high hygroscopicity are present in the siloxane resin, it is preferable that the side chain of the polycarbosilane is hydrogen. This is because silanol groups and hydrogen react to reduce silanol groups.

  If the amount of polycarbosilane added is too small, sufficient alkali resistance and moisture resistance cannot be obtained. Moreover, when there is too much addition amount, the adhesiveness of a film will fall. For this reason, it is preferable that the addition amount of polycarbosilane shall be 10-300 weight part with respect to 100 weight part of siloxane resin.

  The low dielectric constant film-forming material according to the above-described embodiment is spin-coated on the surface of the semiconductor substrate, the solvent is evaporated at 120 to 250 ° C., and heat treatment is performed at 300 ° C. or higher to crosslink, so that the siloxane resin is polycarbohydrate. A low dielectric constant film bonded with silane can be formed.

Next, a first example of a specific method for producing a low dielectric constant film forming material will be described.
In 39.6 g of methyl isobutyl ketone, 20.8 g (0.1 mol) of tetraethoxysilane and 17.8 g (0.1 mol) of methyltriethoxysilane are dissolved. 16.2 g (0.9 mol) of nitric acid having a concentration of 400 ppm is added dropwise over 10 minutes, and an aging reaction is performed for 2 hours after the completion of the addition. Tetraethoxysilane and methyltriethoxysilane are copolymerized to produce a siloxane resin.

  Next, 5 g of magnesium nitrate is added to remove excess water. Using a rotary evaporator, the ethanol produced by the aging reaction is removed until the reaction solution reaches 50 ml. 20 ml of methyl isobutyl ketone is added to the obtained reaction solution to obtain a siloxane resin solution.

10 to 300 parts by weight of polycarbosilane having a weight average molecular weight of 20,000 is added to the siloxane resin solution with respect to 100 parts by weight of the siloxane resin (solid content). Through the steps so far, a resin solution for forming a low dielectric constant film is obtained. Note that the polycarbosilane used has a (—SiH (CH ₃ ) —CH ₂ —) skeleton.

For comparison, a resin solution to which polycarbosilane was not added and a resin solution in which the addition amount of polycarbosilane was 5 parts by weight and 350 parts by weight were prepared.
Next, a method for producing a low dielectric constant film forming material according to the second embodiment will be described. In the first example, 20.8 g of tetraethoxysilane and 17.8 g of methyltriethoxysilane were used as raw materials for the siloxane resin. In the second example, 20.8 g of tetraethoxysilane (0.1 Mol) and 16.4 g (0.1 mol) of triethoxysilane. The generation process is the same as in the first embodiment. In addition, the isobutyl ketone used is 37.2g.

Next, a method for producing a low dielectric constant film forming material according to the third embodiment will be described. 88 g (0.9 mol) of sulfuric acid and 33 g of fuming sulfuric acid (60% SO ₄ ) are charged into a reaction vessel equipped with a nitrogen gas introduction pipe and a liquid metering pump. Fuming sulfuric acid is added to perform dehydration in the reaction vessel. Toluene 87 g (0.95 mol) is added dropwise at a rate of 2 ml / min with a metering pump, and an aging reaction is carried out for 1 hour after completion of the addition. By this aging reaction, toluenesulfonic acid hydrate is produced.

  A solution obtained by dissolving 41 g (0.3 mol) of trichlorosilane in toluene so as to have a concentration of 20% by weight is dropped by a metering pump under the condition of 2 ml / min. After completion of the dropping, an aging reaction is performed for 2 hours. By this aging reaction, a ladder-type siloxane resin is synthesized. After completion of the reaction, 100 ml of 50% by weight sulfuric acid aqueous solution is added to remove the precipitated toluenesulfonic acid. Excess sulfuric acid aqueous solution is removed using a separatory funnel.

  The remaining sulfuric acid is neutralized with 2 g of calcium carbonate. After dehydrating with 5 g of magnesium nitrate, toluene is removed using a rotary evaporator. The solid material of hydrogen silsesquioxane resin 15g was obtained by the process so far. The obtained hydrogen silsesquioxane resin was dissolved in 70 g of methyl isobutyl ketone to obtain a solution having a solid content concentration of 17.5% by weight.

  To the resulting solution, 20 to 300 parts by weight of polycarbosilane having a weight average molecular weight of 20,000 is added with respect to 100 parts by weight of the solid content in the solution. Through the steps so far, a resin solution for forming a low dielectric constant film is obtained.

  Next, a method for producing a low dielectric constant film forming material according to the fourth embodiment will be described. In the third example, 41 g of trichlorosilane was used as a raw material for hydrogen silsesquioxane, but in the fourth example, 36 g (0.27 mol) of trichlorosilane and 4.6 g (0.03) of fluorotrichlorosilane were used. Mol). The generation process is the same as that in the third embodiment.

In the fourth embodiment, a resin solution containing 15 g of fluorine-containing hydrogen silsesquioxane resin and polycarbosilane is obtained.
Next, a method for forming a low dielectric constant film using the low dielectric constant film forming material (resin solution) according to the first to fourth embodiments will be described.

  The resin solutions according to the first to fourth embodiments are spin-coated on the silicon wafer surface. The rotation speed is 3000 rpm, and the coating time is 20 seconds. After spin coating, the solvent is evaporated at 200 ° C. Heat treatment is performed at 400 ° C. for 30 minutes in a nitrogen atmosphere with an oxygen concentration of 100 ppm or less. By this heat treatment, the siloxane resin and the polycarbosilane are cross-linked to form a low dielectric constant film.

  FIG. 1 shows the relationship between the relative dielectric constant of the low dielectric constant film and the amount of polycarbosilane added. The horizontal axis represents the amount of polycarbosilane added to 100 parts by weight of the siloxane resin in the unit of “parts by weight”, and the vertical axis represents the relative dielectric constant of the low dielectric constant film. White circles, squares, triangles, and rhombuses in the figure indicate the relative dielectric constants of the low dielectric constant films produced using the film forming materials according to the first to fourth examples, respectively. For reference, the relative dielectric constant in the comparative example in which no polycarbosilane is added and in the comparative example in which the amount of polycarbosilane added is 350 parts by weight is the same as that in the corresponding example. Is shown.

  In any of the examples, the relative dielectric constant is about 2.5 to 3, which is smaller than the relative dielectric constant of the insulating film using silicon dioxide. In particular, in the case of the first and second examples, it can be seen that the relative dielectric constant is reduced by adding polycarbosilane.

FIG. 2 shows the relationship between the adhesion of the low dielectric constant film and the amount of polycarbosilane added. The degree of adhesion was measured with a Sebastian measuring instrument after attaching a stud pin having a diameter of 2 mm to the surface of the coating with an epoxy resin. The horizontal axis of FIG. 2 represents the amount of polycarbosilane added in the unit “part by weight”, and the vertical axis represents the tensile force per unit area when peeling occurs in the unit “N / cm ² ”. The meaning of each symbol in the figure is the same as in FIG.

  The adhesion degree of the comparative example in which the addition amount of polycarbosilane was 350 parts by weight is lower than the adhesion degree in the example in which the addition amount of polycarbosilane was 300 parts by weight or less. For this reason, it is preferable that the addition amount of polycarbosilane shall be 300 weight part or less with respect to 100 weight part of siloxane resins.

  Next, the alkali resistance of the low dielectric constant film will be described. After the formed low dielectric constant film was immersed in an aqueous tetramethylammonium hydride solution having a concentration of 2.38% for 1 minute, the surface state of the film was observed. In the case of the comparative example in which no polycarbosilane was added and in the case of the comparative example in which the amount of polycarbosilane added was 5 parts by weight, generation of cracks was confirmed in the coating. In the case of the first to fourth examples in which the amount of polycarbosilane added was 10 to 300 parts by weight, the occurrence of cracks was not confirmed. In order to ensure high alkali resistance, the amount of polycarbosilane added is preferably 10 parts by weight or more with respect to 100 parts by weight of the siloxane resin.

  Next, a method for producing a low dielectric constant film forming material according to the fifth to eighth embodiments will be described. The low dielectric constant film forming materials according to the fifth to eighth embodiments are prepared by adding adamantane monophenol to the siloxane resin solution to which the polycarbosilane according to the first to fourth embodiments is added. The amount of polycarbosilane added is 150 parts by weight with respect to 100 parts by weight of the siloxane resin. The addition amount of adamantane monophenol is 0 to 70% by weight based on the mixture of siloxane resin and polycarbosilane. For comparison, a resin solution was prepared in which the amount of adamantane monophenol added was 80% by weight with respect to the mixture of siloxane resin and polycarbosilane.

  The resin solutions according to the fifth to eighth examples and the comparative example were spin-coated on the silicon wafer surface to form a low dielectric constant film. During the heat treatment for crosslinking, adamantane monophenol is desorbed and a porous film is obtained.

  FIG. 3 shows the relationship between the relative dielectric constant of the porous low dielectric constant film and the amount of adamantane monophenol added. The horizontal axis represents the added amount of adamantane monophenol in the unit of “wt%”, and the vertical axis represents the relative dielectric constant. White circles, squares, triangles, and rhombuses in the figure indicate relative dielectric constants of the films formed using the resin solutions according to the fifth to eighth examples, respectively. As can be seen from a comparison between FIG. 1 and FIG. 3, the dielectric constant of the coating can be further reduced by making the coating porous.

FIG. 4 shows the relationship between the degree of adhesion of the porous low dielectric constant film and the amount of adamantane monophenol added. The abscissa represents the amount of adamantane monophenol added in weight% with respect to the mixture of the siloxane resin and polycarbosilane, and the ordinate represents the degree of adhesion in the unit “N / cm ² ”. The degree of adhesion was measured by the same method as described in FIG.

  When the addition amount of adamantane monophenol is increased from 70% by weight to 80% by weight, the degree of adhesion of the film is rapidly lowered. For this reason, it is preferable that the addition amount of adamantane monophenol is 70% by weight or less.

  Next, a method for inspecting whether or not polycarbosilane is added to the siloxane resin will be described. Polycarbosilane has a (—Si—CH 2 —Si—) skeleton. On the other hand, a siloxane resin has a (—Si—O—Si—) skeleton.

The inclusion of the (—Si—CH 2 —Si—) bond is confirmed by a peak appearing at 1080 to 1040 cm ⁻¹ in the infrared spectrum. Note that this peak partially overlaps with the peak corresponding to the (—Si—O—Si—) bond, but since these peaks are steep, it is possible to distinguish both peaks. Whether or not the low dielectric constant film formed on the semiconductor substrate contains polycarbosilane can be determined by microinfrared spectroscopy.

Next, the structure of the semiconductor device according to the ninth embodiment manufactured using the film forming materials according to the first to eighth embodiments and the manufacturing method thereof will be described.
FIG. 5 shows a cross-sectional view of a semiconductor device having aluminum (Al) wiring. An active region is defined by a field oxide film 2 formed on the surface of the silicon substrate 1. A MOSFET 3 is formed in the active region. The MOSFET 3 includes a source region 3S, a drain region 3D, a gate electrode 3G, and a gate oxide film 3I.

An interlayer insulating film 10 made of SiO ₂ and a stopper film 11 made of SiN are formed on the substrate so as to cover the MOSFET 3. A contact hole 12 is formed in the interlayer insulating film 10 at a position corresponding to the drain region 3D. A barrier layer 13 made of TiN covers the side and bottom surfaces of the contact hole 12. Further, a plug 14 made of tungsten (W) fills the contact hole 12.

  The barrier layer 13 and the plug 14 are formed by depositing a TiN film and a W film on the entire surface of the substrate and then performing chemical mechanical polishing (CMP). The TiN film is deposited by sputtering. The deposition of the W film is performed by chemical vapor deposition (CVD) using tungsten hexafluoride and hydrogen.

  A first layer wiring 20 is formed on the surface of the stopper film 11. The first-layer wiring 20 has a three-layer structure in which a TiN film 21 having a thickness of 50 nm, a Cu-containing Al film 22 having a thickness of 450 nm, and a TiN film 23 having a thickness of 50 nm are stacked in this order. Patterning of the TiN film and the Al film is performed by plasma etching using hydrochloric acid gas. A part of the first layer wiring 20 is electrically connected to the W plug 14.

The surface of the first layer wiring 20 and the stopper film 11 is covered with a liner film 25 made of SiO ₂ and having a thickness of 50 nm. The liner film 25 is formed by CVD using tetraethylorthosilicate (TEOS) and oxygen.

  A low dielectric constant film 26 is formed on the liner film 25. The low dielectric constant film 26 is formed by spin coating the siloxane resin solutions according to the first to eighth embodiments. The low dielectric constant film 26 is formed under the condition that the thickness is 500 nm on the flat surface of the silicon substrate.

On the low dielectric constant film 26, a cap layer 27 made of SiO ₂ and having a thickness of 1000 nm is formed. The cap layer 27 is performed by CVD using TEOS and oxygen. The upper surface of the cap layer 27 is planarized by CMP. This polishing is performed so that the total film thickness of the liner film 25, the low dielectric constant film 26, and the cap layer 27 is 1200 nm in a portion where the first-layer wiring 20 is not disposed.

Via holes 28 are formed in the three layers of the liner film 25, the low dielectric constant film 26, and the cap layer 27. The via hole 28 is formed by plasma etching using CF ₄ and CHF ₃ . A barrier layer 29 made of TiN covers the side and bottom surfaces of the via hole 28. A W plug 30 fills the via hole 28. The barrier layer 29 and the W plug 30 are formed by the same method as the formation of the lower barrier layer 13 and the plug 14.

  A second-layer wiring 40 is formed on the cap layer 27. A second layer liner film 41, a low dielectric constant film 42, and a cap layer 43 are laminated so as to cover the second layer wiring 40. These are formed by a method similar to the formation of the corresponding portion of the first layer.

  In the multilayer wiring structure shown in FIG. 5, a space between adjacent wirings in the same wiring layer is filled with a low dielectric constant film. For this reason, the parasitic capacitance between wirings can be reduced. Further, since the low dielectric constant films 26 and 41 are formed using the film forming material according to the above embodiment, the hygroscopicity of the film does not increase even when the treatment using the alkaline solution is performed, and the low dielectric constant is obtained. Can be maintained.

  FIG. 6 shows a cross-sectional view of a semiconductor device having copper (Cu) wiring. The structure from the silicon substrate 1 to the stopper film 11 is the same as the structure of the corresponding part of the semiconductor device shown in FIG. These constituent parts in FIG. 6 are assigned the same reference numerals as those in the corresponding parts in FIG.

A low dielectric constant film 50 is formed on the stopper film 11. The low dielectric constant film 50 is formed using the film forming material according to the above-described embodiment under the condition that the thickness is 450 nm on the flat surface of the silicon substrate. A cap layer 51 made of SiO ₂ and having a thickness of 50 nm is formed on the low dielectric constant film 50. The cap layer 51 is formed by CVD using TEOS and oxygen.

A first layer wiring groove 52 is formed in the low dielectric constant film 50 and the cap layer 51. The first layer wiring groove 52 is formed by plasma etching using CF ₄ and CHF ₃ . The upper surface of the plug 14 appears on the bottom surface of the first layer wiring groove 52.

  The side surface and the bottom surface of the first layer wiring groove 52 are covered with a barrier layer 53 made of TaN and having a thickness of 50 nm. A first layer wiring 54 made of Cu fills the wiring groove 52. Hereinafter, a method of forming the barrier layer 53 and the first layer wiring 54 will be described.

  A TaN film is formed on the entire surface of the substrate including the inner surface of the first layer wiring groove 52 by sputtering. Further, a Cu film having a thickness of 50 nm is formed thereon by sputtering. A Cu film having a thickness of 600 nm is formed by electrolytic plating using the Cu film as an electrode. Excess Cu film and TaN film are removed by CMP to leave the barrier layer 53 and the first layer wiring 54 in the first layer wiring groove 52.

  On the cap layer 51, a 50 nm thick diffusion prevention film 60 made of SiN, a low dielectric constant film 61, a 50 nm thick stopper film 62, a low dielectric constant film 63, and a 50 nm thick cap made of SiN. Layer 64 is laminated. The diffusion prevention film 60 and the stopper film 62 are formed by plasma CVD using silane and ammonia gas. The low dielectric constant films 61 and 63 are formed using the film forming material according to the above embodiment. The low dielectric constant films 61 and 63 are formed under the condition that the thicknesses are 650 nm and 400 nm on the flat surface of the silicon substrate, respectively.

  A via hole 68 is formed in the diffusion preventing film 60 and the low dielectric constant film 61. A second-layer wiring groove 69 is formed in the stopper film 62, the low dielectric constant film 63 and the cap layer 64. The inner surfaces of the via hole 68 and the second layer wiring groove 69 are covered with a barrier layer 70 made of TaN and having a thickness of 50 nm. A second layer wiring 72 made of Cu fills the via hole 68 and the second layer wiring groove 69. The second layer wiring 72 is formed by a dual damascene method.

  The dual damascene method will be briefly described below. First, a via hole 68 extending from the cap layer 64 to the upper surface of the first layer wiring 54 is formed. Next, a second-layer wiring groove 69 reaching from the cap layer 64 to the upper surface of the low dielectric constant film 61 is formed. The formation of the barrier layer 70 and the second layer wiring 72 is performed in the same manner as the formation of the lower barrier layer 53 and the first layer wiring 54.

  Since the first layer wiring 54 and the second layer wiring 72 are surrounded by the low dielectric constant films 50, 61, and 63, the parasitic capacitance between the wirings can be reduced. In addition, since these low dielectric constant films 50, 61, and 63 are formed using the film forming material according to the above-described embodiment, even if treatment with an alkaline solution is performed, the hygroscopicity does not increase and the dielectric constant is increased. Can be kept small.

  Next, with reference to FIG. 7, a semiconductor device according to the tenth embodiment and a method for manufacturing the same will be described. In the semiconductor device according to the ninth embodiment shown in FIG. 6, the stopper film 62 made of silicon nitride is disposed between the low dielectric constant film 61 and the low dielectric constant film 63 thereon. In the tenth embodiment, the stopper film 62 is not disposed, and the low dielectric constant film 63 is in contact with the low dielectric constant film 61.

  In the tenth embodiment, the low dielectric constant films 61 and 63 are formed of a silica-based porous material. Under the same etching conditions, the etching rate of the upper low dielectric constant film 63 is faster than the etching rate of the lower low dielectric constant film 61. Other configurations are the same as those of the ninth embodiment shown in FIG.

  The low dielectric constant films 61 and 63 are, for example, of the general formula

で表されるシロキサン樹脂、または、一般式

A siloxane resin represented by the general formula

で表されるラダー型シロキサン樹脂を含む。

The ladder type siloxane resin represented by these is included.

Here, R _{10 to} R ₁₂ are hydrogen, oxygen, or a monovalent hydrocarbon group, and R _{13 to} R ₁₆ are hydrogen, fluorine, or a monovalent hydrocarbon group. n ₁ is an integer of ₅ to 200, and X is hydrogen or silicon. n ₂ is an integer of 5 to 100.

In the lower low dielectric constant film 61, at least one of R _{10 to} R ₁₂ or at least one of R _{13 to} R ₁₆ is a phenyl group or a hydrocarbon group having 2 to 5 carbon atoms. In the upper low dielectric constant film 63, R _{10 to} R ₁₂ are not hydrocarbon groups having 2 or more carbon atoms, and R _{13 to} R ₁₆ are not hydrocarbon groups having 2 or more carbon atoms.

  The inventors of the present application have found that the etching rate is changed by changing the side chain of the siloxane resin or the ladder type siloxane resin. Specifically, when the side chain is only hydrogen or a methyl group, fluorine plasma is generated as compared with the case where at least one side chain of one monomer unit is a phenyl group or a hydrocarbon group having 2 or more carbon atoms. The etching rate when the used etching is performed is three times or more faster. In the tenth embodiment, these materials are selected so that the etching rate of the upper low dielectric constant film 63 is three times or more that of the lower low dielectric constant film 61.

Next, a method for manufacturing an example of the material of the lower dielectric constant film 61 will be described. In 37.2 g of methyl isobutyl ketone, 20.8 g (0.1 mol) of tetraethoxysilane and 20.4 g (0.1 mol) of phenyltriethoxysilane are dissolved to obtain 200 ml of a solution. To this solution, 16.2 g (0.9 mol) of nitric acid having a concentration of 400 ppm is added dropwise over 10 minutes, and an aging reaction is performed for 2 hours after the completion of the addition. Tetraethoxysilane and phenyltriethoxysilane are copolymerized to produce a siloxane resin. In this siloxane resin, at least one of R _{10 to} R _{12 in} the above general formula is a phenyl group, and the other is an oxygen atom. Note that a hydrogen atom or a silicon atom is bonded to the other bond of the oxygen atom.

  To this siloxane resin solution, 5 g of magnesium sulfate is added to remove excess water. Using a rotary evaporator, the solvent containing ethanol, which is a by-product generated by the aging reaction, is removed until the reaction solution reaches 50 ml. To the obtained reaction solution, 0.1 g of adamantane monophenol is added. Thereby, a siloxane resin solution for forming the lower dielectric constant film 61 is obtained. Note that adamantane monophenol is a releasing agent for making the low dielectric constant film porous.

Next, an example of a method for manufacturing the material of the upper low dielectric constant film 63 will be described. In 39.6 g of methyl isobutyl ketone, 20.8 g (0.1 mol) of tetraethoxysilane and 17.8 g (0.1 mol) of methyltriethoxysilane are dissolved to obtain a 200 ml solution. To this solution, 16.2 g (0.9 mol) of nitric acid having a concentration of 400 ppm is added dropwise over 10 minutes, and an aging reaction is performed for 2 hours after the completion of the addition. Tetraethoxysilane and methyltriethoxysilane are copolymerized to produce a siloxane resin. In this siloxane resin, at least one of R _{10 to} R _{12 in} the above general formula is a methyl group, and the other is oxygen. Note that a hydrogen atom or a silicon atom is bonded to the other bond of the oxygen atom.

  Thereafter, in the same manner as in the synthesis of the lower dielectric constant coating material, the excess water is removed, and the solvent containing ethanol, which is a by-product generated by the aging reaction, is removed until the reaction solution reaches 50 ml. To the obtained reaction solution, 0.1 g of adamantane monophenol is added. As a result, a siloxane resin solution for forming the upper low dielectric constant film 63 is obtained.

Next, a method for manufacturing the semiconductor device shown in FIG. 7 using the above-described low dielectric constant film material will be described.
The process up to the formation of the diffusion prevention film 60 is the same as the method of manufacturing the semiconductor device according to the ninth embodiment shown in FIG. On the diffusion prevention film 60, a siloxane resin solution which is a lower dielectric constant coating material is spin-coated. The solvent is dried at a temperature of 200 ° C. Annealing is performed at a temperature of 400 ° C. for 30 minutes in a nitrogen atmosphere with an oxygen concentration of 100 ppm or less. Thereby, the low dielectric constant film 61 made of the lower silica-based porous material having a thickness of 500 nm is formed.

  A siloxane resin solution, which is an upper low dielectric constant film material, is spin-coated on the lower low dielectric constant film 61, the solvent is dried, and annealing is performed to form an upper low dielectric constant film 63 having a thickness of 400 nm. To do. The conditions for drying the solvent and annealing are the same as those for forming the lower low dielectric constant film 61.

  A cap layer 64 made of silicon oxide and having a thickness of 50 nm is formed on the low dielectric constant film 63 by chemical vapor deposition (CVD) using tetraethylorthosilicate (TEOS).

A resist pattern having an opening corresponding to the via hole 68 is formed on the surface of the cap layer 64. A hole reaching from the cap layer 64 to the upper surface of the first layer wiring 54 is formed using fluorine plasma using CF ₄ and CHF ₃ as raw materials. After removing the resist pattern, a resist pattern having an opening corresponding to the second layer wiring groove 69 is newly formed on the surface of the cap layer 64.

The upper layer low dielectric constant film 63 is etched using fluorine plasma using C ₂ F ₆ and O ₂ as raw materials to form the second layer wiring groove 69. This etching is performed under the conditions that the flow rate of C ₂ F ₆ is 40 sccm, the flow rate of O ₂ is 10 sccm, the input power for generating inductively coupled plasma is 200 W, and the gas pressure is 5.32 Pa (40 mTorr). Under this etching condition, the etching rate of the upper low dielectric constant film 63 is about 100 nm / min, and the etching rate of the lower low dielectric constant film 61 is about 30 nm / min. Thus, since the etching rate of the lower low dielectric constant film 61 is slower than the etching rate of the upper low dielectric constant film 63, the upper surface of the lower low dielectric constant film 61 can be formed without an etching stop layer. When it appears, etching can be stopped with good controllability. In order to stop the etching with good controllability, it is preferable that the etching rate of the upper low dielectric constant film 63 under the same etching conditions is twice or more the etching rate of the lower low dielectric constant film 61.

The resist pattern is removed, and the barrier layer 70 and the second layer wiring 72 are formed. The formation of the barrier layer 70 and the second layer wiring 72 is the same as in the first embodiment shown in FIG.
In the tenth embodiment, since a silicon nitride film having a relatively high dielectric constant is not disposed between the lower low dielectric constant film 61 and the upper low dielectric constant film 63, the parasitic capacitance between the wirings is further increased. Can be reduced. Actually, when the effective relative dielectric constant was measured by arranging the two second layer wirings 72 in parallel with each other and measuring the capacitance between them, it was about 2.5. On the other hand, the effective relative dielectric constant in the case of the ninth embodiment shown in FIG. 6 was 2.8.

  Further, in order to measure the relative dielectric constant of the laminated structure of the low dielectric constant film, as a raw material, a low dielectric constant film of a lower layer of 300 nm thickness, a low dielectric constant film of an upper layer of 300 nm thickness, and a raw material An evaluation sample in which a silicon oxide film having a thickness of 50 nm formed using TEOS was stacked was manufactured. An Au film having a diameter of 1 mm and a thickness of 100 nm was formed on the surface of the uppermost silicon oxide film, and the capacitance between the silicon substrate and the Au film was measured. From this measurement result, the relative dielectric constant of a three-layer structure consisting of a low dielectric constant film and silicon oxide was found to be 2.4. On the other hand, the relative dielectric constant of the four-layer structure in which the silicon nitride film having a thickness of 50 nm is disposed between the two layers of the low dielectric constant film was 2.7. Note that the relative dielectric constant of silicon oxide alone formed using TEOS is about 4, and the relative dielectric constant of silicon nitride alone is about 7.

  As can be seen from the tenth embodiment described above and the evaluation results, by not providing an etching stopper film made of silicon nitride, the relative dielectric constant of the laminated structure including the low dielectric constant film can be reduced.

  As an upper layer low dielectric constant coating material, the siloxane resin used in the tenth embodiment, a resin produced by a sol-gel method using tetraalkoxysilane, trialkoxysilane, methyltrialkoxysilane and the like as raw materials, or a mixture thereof And a resin produced by a sol-gel method using tetraalkoxysilane and dimethyl dialkoxysilane as a raw material. Examples of the ladder type resin include hydrogen silsesquioxane, methyl silsesquioxane, fluorine-containing hydrogen silsesquioxane, and the like.

  Examples of the low dielectric constant film material for the lower layer include the siloxane resin used in the tenth embodiment and resins produced by sol-gel method using phenyltrialkoxysilane as a raw material. Examples of the ladder type resin include phenyl silsesquioxane. The resin having at least one side chain of a hydrocarbon group having 2 to 5 carbon atoms was selected from ethyltrialkoxysilane, propyltrialkoxysilane, normal-butyltrialkoxysilane, tertiary-butyltrialkoxysilane, and the like. A resin produced by a sol-gel method using at least one as a raw material can be mentioned.

The invention shown in the following supplementary notes is derived from the various embodiments described above.
(Additional remark 1) The low dielectric constant film forming material which melt | dissolved siloxane resin and polycarbosilane.
(Supplementary Note 2) The weight average molecular weight of the siloxane resin is 1,000 to 500,000, and the polycarbosilane is dissolved in 10 to 300 parts by weight with respect to 100 parts by weight of the siloxane resin. Low dielectric constant film forming material.
(Additional remark 3) Furthermore, the organic compound which remove | desorbs by heating or light irradiation is melt | dissolving, The quantity is 10 to 70 weight% with respect to the mixture of the said siloxane resin and polycarbosilane. The low dielectric constant film-forming material described.
(Appendix 4) The general formula is

（Ｒ₁〜Ｒ₃は水素、酸素もしくは１価の炭化水素基、Ｘは水素もしくはシリコン、ｎ₁は５〜２００の整数）
もしくは、

(R _{1 to} R ₃ are hydrogen, oxygen or a monovalent hydrocarbon group, X is hydrogen or silicon, and n ₁ is an integer of 5 to 200)
Or

（Ｒ₄〜Ｒ₇は水素、フッ素もしくは１価の炭化水素基、ｎ₂は５〜１００の整数、ただし、Ｒ₄〜Ｒ₇のうち少なくとも１つは水素）
で表されるシロキサン樹脂１００重量部と、
一般式が

(R _{4 to} R ₇ are hydrogen, fluorine or a monovalent hydrocarbon group, n ₂ is an integer of 5 to 100, but at least one of R _{4 to} R ₇ is hydrogen)
100 parts by weight of a siloxane resin represented by
The general formula is

（Ｒ₈及びＲ₉は、水素もしくは１価の炭化水素基、ｍは２０〜１０００の整数）で表されるポリカルボシラン１０〜３００重量部と
を溶剤に溶解させた低誘電率被膜形成材料。
（付記５） さらに、加熱もしくは光照射により脱離する有機化合物が前記溶剤に溶解しており、その量が、前記シロキサン樹脂とポリカルボシランとの混合物に対し１０〜７０重量％である付記４に記載の低誘電率被膜形成材料。
（付記６） シロキサン樹脂と、
該シロキサン樹脂に結合したポリカルボシランと
を含む低誘電率被膜。
（付記７） 半導体基板と、
前記半導体基板の主表面上に配置され、シロキサン樹脂と、該シロキサン樹脂に結合したポリカルボシランとを含む低誘電率材料からなる低誘電体膜と
を有する半導体装置。
（付記８） 半導体基板と、
前記基板の表面上に形成され、第１のシリカ系多孔質材料からなる第１の膜と、
前記第１の膜の上に直接形成され、同一エッチング条件の下で、前記第１のシリカ系多孔質材料とはエッチング速度の異なる第２のシリカ系多孔質材料からなる第２の膜と
を有する半導体装置。
（付記９） 前記第１のシリカ系多孔質材料と第２のシリカ系多孔質材料との同一エッチング条件下でのエッチング速度の速い方が遅い方の２倍以上である付記８に記載の半導体装置。
（付記１０） 前記第１及び第２のシリカ系多孔質材料が、一般式

A low dielectric constant film-forming material obtained by dissolving 10 to 300 parts by weight of polycarbosilane represented by the formula (R ₈ and R ₉ are hydrogen or a monovalent hydrocarbon group, m is an integer of 20 to 1000) .
(Additional remark 5) Furthermore, the organic compound which remove | desorbs by heating or light irradiation is melt | dissolving in the said solvent, The amount is 10 to 70 weight% with respect to the mixture of the said siloxane resin and polycarbosilane. 2. A low dielectric constant film-forming material described in 1.
(Appendix 6) A siloxane resin;
A low dielectric constant film comprising polycarbosilane bonded to the siloxane resin.
(Appendix 7) a semiconductor substrate;
A semiconductor device having a low dielectric film made of a low dielectric constant material, which is disposed on a main surface of the semiconductor substrate and includes a siloxane resin and polycarbosilane bonded to the siloxane resin.
(Appendix 8) a semiconductor substrate;
A first film formed on the surface of the substrate and made of a first silica-based porous material;
A second film formed directly on the first film and made of a second silica-based porous material having an etching rate different from that of the first silica-based porous material under the same etching conditions. A semiconductor device having the same.
(Supplementary note 9) The semiconductor according to supplementary note 8, wherein the faster etching rate under the same etching conditions of the first silica-based porous material and the second silica-based porous material is twice or more the slower one. apparatus.
(Additional remark 10) Said 1st and 2nd silica type porous material is general formula.

（Ｒ₁₀〜Ｒ₁₂は水素、酸素もしくは１価の炭化水素基、ｎ₁は５〜２００の整数、Ｘは水素もしくはシリコン）
もしくは、一般式

(R _{10 to} R ₁₂ are hydrogen, oxygen or a monovalent hydrocarbon group, n ₁ is an integer of 5 to 200, and X is hydrogen or silicon)
Or general formula

（Ｒ₁₃〜Ｒ₁₆は水素、フッ素もしくは１価の炭化水素基、ｎ₂は５〜１００の整数、ただし、Ｒ₁₃〜Ｒ₁₆のうち少なくとも１つは水素）
で表されるシロキサン樹脂を含む付記８または９に記載の半導体装置。
（付記１１） 前記第１のシリカ系多孔質材料においては、Ｒ₁₀〜Ｒ₁₂のうち少なくとも１つがフェニル基もしくは炭素数２〜５の炭化水素基であるか、またはＲ₁₃〜Ｒ₁₆のうち少なくとも１つがフェニル基もしくは炭素数２〜５の炭化水素基であり、前記第２のシリカ系多孔質材料においては、Ｒ₁₀〜Ｒ₁₂のいずれも炭素数２以上の炭化水素基ではないか、またはＲ₁₃〜Ｒ₁₆のいずれも炭素数２以上の炭化水素基ではない付記１０に記載の半導体装置。
（付記１２） 前記第２のシリカ系多孔質材料のエッチング速度が第１のシリカ系多孔質材料のエッチング速度よりも速く、
さらに、深さが前記第２の膜の厚さ以上であり、該第２の膜内に形成された溝と、
前記溝と一部重なる位置に配置され、前記第１の膜を貫通するビアホールと、
前記ビアホール及び配線溝の内部を埋め込む導電性の配線と
を有する付記８〜１１のいずれかに記載の半導体装置。
（付記１３） 半導体基板の表面上に、第１のシリカ系多孔質材料からなる第１の膜を形成する工程と、
同一エッチング条件の下で、前記第１のシリカ系多孔質材料よりもエッチング速度の速い第２のシリカ系多孔質材料からなる第２の膜を、前記第１の膜の表面上に、直接形成する工程と、
前記第２の膜の厚さ以上の深さを有する溝と、該溝と一部重なる位置に配置され、前記第１の膜を貫通するビアホールとを形成する工程と、
前記ビアホール及び前記溝内に、導電性の部材を埋め込む工程と
を有する半導体装置の製造方法。
（付記１４） 前記溝とビアホールとを形成する工程が、
前記第１の膜と前記第２の膜とを貫通する穴を形成する工程と、
前記穴と一部重なる領域を、前記第２の膜の上面から、少なくとも前記第１の膜の上面までエッチングし、前記溝を形成する工程と
を含む請求項１３に記載の半導体装置の製造方法。
（付記１５） 半導体基板と、
前記基板の表面上に形成され、第１のシリカ系多孔質材料からなる第１の膜と、
前記第１の膜の上に直接形成され、第２のシリカ系多孔質材料からなる第２の膜と
を有し、
前記第１及び第２のシリカ系多孔質材料が、一般式

(R ₁₃ to R ₁₆ is hydrogen, fluorine or a monovalent hydrocarbon group, n ₂ is from 5 to 100 an integer, provided that at least one hydrogen of R ₁₃ to R ₁₆₎
The semiconductor device according to appendix 8 or 9, comprising a siloxane resin represented by:
(Supplementary Note 11) In the first silica-based porous material, at least one of R _{10 to} R ₁₂ is a phenyl group or a hydrocarbon group having 2 to 5 carbon atoms, or of R _{13 to} R ₁₆ . At least one is a phenyl group or a hydrocarbon group having 2 to 5 carbon atoms, and in the second silica-based porous material, any of R _{10 to} R ₁₂ is a hydrocarbon group having 2 or more carbon atoms, Or the semiconductor device according to appendix 10, wherein any of R _{13 to} R ₁₆ is not a hydrocarbon group having 2 or more carbon atoms.
(Appendix 12) The etching rate of the second silica-based porous material is faster than the etching rate of the first silica-based porous material,
And a depth equal to or greater than the thickness of the second film, and a groove formed in the second film;
A via hole disposed at a position partially overlapping the groove and penetrating the first film;
12. The semiconductor device according to any one of appendices 8 to 11, having conductive vias filling the via holes and the wiring trenches.
(Additional remark 13) The process of forming the 1st film | membrane which consists of a 1st silica type porous material on the surface of a semiconductor substrate,
A second film made of a second silica-based porous material having an etching rate faster than that of the first silica-based porous material is directly formed on the surface of the first film under the same etching conditions. And a process of
Forming a groove having a depth equal to or greater than the thickness of the second film, and a via hole disposed at a position partially overlapping with the groove and penetrating the first film;
A method of manufacturing a semiconductor device, comprising: embedding a conductive member in the via hole and the groove.
(Supplementary Note 14) The step of forming the groove and the via hole includes:
Forming a hole penetrating the first film and the second film;
The method for manufacturing a semiconductor device according to claim 13, further comprising: etching a region partially overlapping with the hole from an upper surface of the second film to at least an upper surface of the first film to form the groove. .
(Supplementary Note 15) a semiconductor substrate;
A first film formed on the surface of the substrate and made of a first silica-based porous material;
A second film formed directly on the first film and made of a second silica-based porous material;
The first and second silica-based porous materials have the general formula

（Ｒ₁₀〜Ｒ₁₂は水素、酸素もしくは１価の炭化水素基、ｎ₁は５〜２００の整数、Ｘは水素もしくはシリコン）
もしくは、一般式

(R _{10 to} R ₁₂ are hydrogen, oxygen or a monovalent hydrocarbon group, n ₁ is an integer of 5 to 200, and X is hydrogen or silicon)
Or general formula

（Ｒ₁₃〜Ｒ₁₆は水素、フッ素もしくは１価の炭化水素基、ｎ₂は５〜１００の整数、ただし、Ｒ₁₃〜Ｒ₁₆のうち少なくとも１つは水素）
で表されるシロキサン樹脂を含み、前記第１のシリカ系多孔質材料においては、Ｒ₁₀〜Ｒ₁₂のうち少なくとも１つがフェニル基もしくは炭素数２〜５の炭化水素基であるか、またはＲ₁₃〜Ｒ₁₆のうち少なくとも１つがフェニル基もしくは炭素数２〜５の炭化水素基であり、前記第２のシリカ系多孔質材料においては、Ｒ₁₀〜Ｒ₁₂のいずれも炭素数２以上の炭化水素基ではないか、またはＲ₁₃〜Ｒ₁₆のいずれも炭素数２以上の炭化水素基ではない半導体装置。
（付記１６） 半導体基板の表面上に、第１のシリカ系多孔質材料からなる第１の膜を形成する工程と、
第２のシリカ系多孔質材料からなる第２の膜を、前記第１の膜の表面上に、直接形成する工程と、
前記第２の膜の厚さ以上の深さを有する溝と、該溝と一部重なる位置に配置され、前記第１の膜を貫通するビアホールとを形成する工程と、
前記ビアホール及び前記溝内に、導電性の部材を埋め込む工程と
を有し、
前記第１及び第２のシリカ系多孔質材料が、一般式

(R ₁₃ to R ₁₆ is hydrogen, fluorine or a monovalent hydrocarbon group, n ₂ is from 5 to 100 an integer, provided that at least one hydrogen of R ₁₃ to R ₁₆₎
In the first silica-based porous material, at least one of R _{10 to} R ₁₂ is a phenyl group or a hydrocarbon group having 2 to 5 carbon atoms, or R ₁₃ At least one of ˜R ₁₆ is a phenyl group or a hydrocarbon group having 2 to 5 carbon atoms, and in the second silica-based porous material, any of R _{10 to} R ₁₂ is a hydrocarbon having 2 or more carbon atoms. A semiconductor device that is not a group or any of R _{13 to} R ₁₆ is not a hydrocarbon group having 2 or more carbon atoms.
(Additional remark 16) The process of forming the 1st film | membrane which consists of a 1st silica type porous material on the surface of a semiconductor substrate,
Directly forming a second film made of a second silica-based porous material on the surface of the first film;
Forming a groove having a depth equal to or greater than the thickness of the second film, and a via hole disposed at a position partially overlapping with the groove and penetrating the first film;
Embedding a conductive member in the via hole and the groove,
The first and second silica-based porous materials have the general formula

（Ｒ₁₀〜Ｒ₁₂は水素、酸素もしくは１価の炭化水素基、ｎ₁は５〜２００の整数、Ｘは水素もしくはシリコン）
もしくは、一般式

(R _{10 to} R ₁₂ are hydrogen, oxygen or a monovalent hydrocarbon group, n ₁ is an integer of 5 to 200, and X is hydrogen or silicon)
Or general formula

（Ｒ₁₃〜Ｒ₁₆は水素、フッ素もしくは１価の炭化水素基、ｎ₂は５〜１００の整数、ただし、Ｒ₁₃〜Ｒ₁₆のうち少なくとも１つは水素）
で表されるシロキサン樹脂を含み、前記第１のシリカ系多孔質材料においては、Ｒ₁₀〜Ｒ₁₂のうち少なくとも１つがフェニル基もしくは炭素数２〜５の炭化水素基であるか、またはＲ₁₃〜Ｒ₁₆のうち少なくとも１つがフェニル基もしくは炭素数２〜５の炭化水素基であり、前記第２のシリカ系多孔質材料においては、Ｒ₁₀〜Ｒ₁₂のいずれも炭素数２以上の炭化水素基ではないか、またはＲ₁₃〜Ｒ₁₆のいずれも炭素数２以上の炭化水素基ではない半導体装置の製造方法。

(R ₁₃ to R ₁₆ is hydrogen, fluorine or a monovalent hydrocarbon group, n ₂ is from 5 to 100 an integer, provided that at least one hydrogen of R ₁₃ to R ₁₆₎
In the first silica-based porous material, at least one of R _{10 to} R ₁₂ is a phenyl group or a hydrocarbon group having 2 to 5 carbon atoms, or R ₁₃ At least one of ˜R ₁₆ is a phenyl group or a hydrocarbon group having 2 to 5 carbon atoms, and in the second silica-based porous material, any of R _{10 to} R ₁₂ is a hydrocarbon having 2 or more carbon atoms. A method for manufacturing a semiconductor device, which is not a group or any of R _{13 to} R ₁₆ is not a hydrocarbon group having 2 or more carbon atoms.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

It is a graph which shows the relationship between the relative dielectric constant of the film formed using the low dielectric constant film forming material by the 1st-4th Example, and the addition amount of polycarbosilane. It is a graph which shows the relationship between the adhesion degree of the film formed using the low dielectric constant film forming material by the 1st-4th Example, and the addition amount of polycarbosilane. It is a graph which shows the relationship between the relative dielectric constant of the film formed using the low dielectric constant film forming material by the 5th-8th Example, and the addition amount of polycarbosilane. It is a graph which shows the relationship between the adhesion degree of the film formed using the low dielectric constant film forming material by the 5th-8th Example, and the addition amount of polycarbosilane. It is sectional drawing of the semiconductor device using the low dielectric constant film by an Example. It is sectional drawing of the semiconductor device using the low dielectric constant film by a 9th Example. It is sectional drawing of the semiconductor device using the low dielectric constant film by a 10th Example.

Explanation of symbols

1 silicon substrate 2 field oxide film 3 MOSFET
10 Interlayer insulating film 11 Stopper film 12 Contact hole 13 Barrier layer 14 Plug 20 First layer wiring 21, 23 TiN film 22 Al film 25, 41 Liner film 26, 42 Low dielectric constant film 27, 43 Cap layer 28 Via hole 29 Barrier Layer 30 Plug 40 Second layer wiring 50, 61, 63 Low dielectric constant film 51, 64 Cap layer 52 First layer wiring groove 53, 70 Barrier layer 54 First layer wiring 60 Diffusion prevention film 62 Stopper film 68 Via hole 69 Second-layer wiring groove 72 Second-layer wiring

Claims (2)

A semiconductor substrate;
A first film formed on the substrate, made of a first porous silica material, and having a via hole;
A second film made of a second silica-based porous material directly formed on the first film and having a wiring groove reaching the via hole;
The first and second silica-based porous materials have the general formula

(R _{10 to} R ₁₂ are hydrogen, oxygen or a monovalent hydrocarbon group, n ₁ is an integer of 5 to 200, X is hydrogen or silicon, and when R _{10 to} R ₁₂ are oxygen, When the same group as X is bonded and X is Si, the (—Si—O—) skeleton extends from the Si atom)
Or general formula

(R _{13 to} R ₁₆ are hydrogen, fluorine or a monovalent hydrocarbon group, n ₂ is an integer of 5 to 100, but at least one of R _{13 to} R ₁₆ is hydrogen)
In the first silica-based porous material, at least one of R _{10 to} R ₁₂ and R _{13 to} R ₁₆ is a phenyl group or a hydrocarbon group having 2 or more carbon atoms. In the second silica-based porous material, R _{10 to} R ₁₂ and R _{13 to} R ₁₆ are hydrogen or a methyl group. Forming a first film made of a first silica-based porous material on a semiconductor substrate;
Forming a second film made of a second silica-based porous material directly on the first film;
Forming a groove having a depth equal to or greater than the thickness of the second film, and a via hole disposed at a position partially overlapping the groove and penetrating the first film;
Embedding a conductive member in the via hole and the groove,
The first and second silica-based porous materials have the general formula

(R _{10 to} R ₁₂ are hydrogen, oxygen or a monovalent hydrocarbon group, n ₁ is an integer of 5 to 200, X is hydrogen or silicon, and when R _{10 to} R ₁₂ are oxygen, When the same group as X is bonded and X is Si, the (—Si—O—) skeleton extends from the Si atom)
Or general formula

(R _{13 to} R ₁₆ are hydrogen, fluorine or a monovalent hydrocarbon group, n ₂ is an integer of 5 to 100, but at least one of R _{13 to} R ₁₆ is hydrogen)
In the first silica-based porous material, at least one of R _{10 to} R ₁₂ and R _{13 to} R ₁₆ is a phenyl group or a hydrocarbon group having 2 or more carbon atoms. In the second silica-based porous material, a method for producing a semiconductor device, wherein R _{10 to} R ₁₂ and R _{13 to} R ₁₆ are hydrogen or a methyl group.

Images