JP5636277B2 - Porous insulating film and method for producing the same - Google Patents

Description

  The present invention relates to a porous insulating film and a method for manufacturing the same.

  Miniaturization of semiconductor manufacturing technology is being promoted toward the realization of LSIs with higher capabilities. Along with this, the resistance of the wiring becomes relatively high and the problem of wiring delay becomes obvious. As a method for alleviating this, it is possible to apply an interlayer insulating film having a lower dielectric constant, and its development has been energetically performed. However, when the dielectric constant is lowered, the mechanical strength and thermal conductivity of the material are usually lowered. Specifically, the relative permittivity of gas is about 1, and the relative permittivity of solid is usually orders of magnitude higher than this. Therefore, if the porosity of the insulating film is increased, the dielectric constant can be lowered accordingly. On the other hand, if the porosity is increased, the mechanical strength and the like are decreased. Both are in a trade-off relationship, making practical application to semiconductor manufacturing difficult.

  U.S. Patent No. 6,057,077 proposes an improved method for sealing the porous sidewalls of an interlayer dielectric (ILD) so as to prevent reactant / solvent diffusion within the porous low-k dielectric. To do. Specifically, a layer of porous low-k dielectric material is provided, and selected portions of the dielectric material are removed to form vias. A thermal decomposable resin is introduced into the via portion to restore the porosity of the dielectric material. The coating is not particularly formed by the thermally decomposable resin, and the thermally decomposable resin is removed by heating after a predetermined treatment.

JP 2008-535212 A

  An object of the present invention is to provide a porous insulating film capable of improving etching damage while maintaining a low dielectric constant and mechanical strength of the insulating film without requiring complicated control in the process, and a method for manufacturing the same. To do.

（一般式（Ｑ−１）〜一般式（Ｑ−７）中、Ｒは、それぞれ独立に、有機基を表し、一般式（Ｑ−１）〜一般式（Ｑ−７）の各々において、Ｒのうちの少なくとも２つは、重合性基を表す。）
（５）前記工程（２）の後に配線もしくはビアを形成する工程を有することを特徴とする（１）〜（４）のいずれか１項に記載の多孔質絶縁膜の製造方法。The above problems have been solved by the following means.
(1) (1) Step of forming a porous insulating film from a composition containing a compound having a siloxane structure (2) Applying a filler to the porous insulating film to backfill the porous portion, and porous insulation A step of forming a polymer coating layer derived from a filler on the upper layer of the membrane (3) A step of removing the polymer coating layer derived from the filler and removing the filler in the backfilled pores, A method for producing a porous insulating film, the method comprising producing at least one of the following (a) to (c) in the step (3):
(A) The polymer coating layer derived from the filler and the filler in the backfilled pores are removed with different solvents.
(B) The polymer coating layer derived from the filler is removed with a solvent, and the filler in the backfilled pores is removed by heating.
(C) The polymer coating layer derived from the filler is removed by a solvent, and the filler in the backfilled pores is removed by heating and a solvent different from the removal solvent of the polymer coating layer.
(2) The method for producing a porous insulating film according to (1), wherein a polymer having a molecular weight of 50,000 or less is used as the filler.
(3) The compound having the siloxane structure is a polymer obtained from silsesquioxanes composed of one or more cage-shaped silsesquioxane compounds represented by the following formula (1). (1) The manufacturing method of the porous insulating film as described in (2) characterized by these.
_(RSiO 1.5) a ··· formula (1)
(In formula (1), R represents an organic group each independently, and at least 2 of R represents a polymeric group. A represents an integer of 8 to 16. Several R are the same. However, a polymerizable group derived from the cage silsesquioxane compound may remain in the polymer.)
(4) The cage-shaped silsesquioxane compound is selected from the group consisting of a cage-shaped silsesquioxane compound represented by any one of the following general formulas (Q-1) to (Q-7) The method for producing a porous insulating film according to (3), which is a seed or two or more kinds.

(In General Formula (Q-1) to General Formula (Q-7), each R independently represents an organic group. In each of General Formula (Q-1) to General Formula (Q-7), R represents At least two of them represent polymerizable groups.)
(5) The method for producing a porous insulating film according to any one of (1) to (4), further comprising a step of forming a wiring or a via after the step (2).

  According to the porous insulating film and the manufacturing method thereof of the present invention, etching damage can be improved while maintaining the low dielectric constant and mechanical strength of the insulating film without requiring complicated control in the process.

It is sectional drawing which showed typically the process of the low-k film | membrane as preferable embodiment of this invention. It is sectional drawing which showed typically the process of a low-k film | membrane as another preferable embodiment of this invention.

  Preferred embodiments of the porous insulating film and the method for producing the same according to the present invention will be described below in detail with reference to the drawings.

[Initial porous insulation film (formation of porous structure)]
In this embodiment, as shown in step (a) in FIG. 1, the initial porous material in which the insulating material layer 2 is formed from a composition containing a compound having a siloxane structure and a large number of pores 1 are formed therein. The insulating film 10 is illustrated. This porous structure can be formed as follows, for example.

  An insulating material layer 2 is formed with a film thickness of, for example, 25 nm on a substrate (not shown) by chemical vapor deposition (CVD). As the insulating material, for example, silicon carbonitride (SiCN), silicon carbide (SiC), silicon nitride (SiN), or the like is suitable. Further, the forming method is not limited to the CVD method, and the film may be formed by other methods. As the substrate, for example, a silicon wafer having a diameter of 300 mm is used. In the figure, illustration of metal wiring, contact plug layers, device portions, etc., which may be arbitrarily formed, is omitted. In addition, various semiconductor elements (not shown) or layers or the like normally applied to the structure thereof may be formed.

As the porogen-containing insulating film forming step, a SiOC film containing a porogen material is formed in a thickness of, for example, 300 nm in the insulating material layer 2 by PE-CVD so as to form the insulating material layer 10. Methyl diethoxy silane (Methyl-di-ethoxy-silane ), alpha-terpinene _{(alpha-terpinene: C 10 H} 16), oxygen _(O 2), it flows into the chamber (not shown) a mixed gas of helium (He) In a state where the pressure in the chamber is maintained at, for example, 1.3 × 10 ³ Pa (10 Torr) or lower, the substrate on which the insulating material layer is formed is heated to, for example, 250 ° C. High frequency power is supplied to the electrodes to generate plasma. Methyldiethoxysilane is a gas for forming a main skeleton component, and alpha terpinene is a gas for forming a porogen component. As a result, a SiOC film containing organosiloxane as a main skeleton component is formed on the insulating material layer, and a large number of pores 1 are formed therein (initial porous insulating film 10).

As the organic silicon gas for forming the main skeleton component forming the insulating material layer, dimethylsilane (Di-Methyl-Silane), trimethylsilane (Tri-Methyl-Silane), tetramethylsilane (Tetra-Methyl-Silane), dimethylphenyl Silane (Di-Methyl-Phenyl-Silane), Trimethylsilylacetylene (Tri-Methyl-Sylyl-Acetylene), Monomethyldiethoxysilane (Mono-Methyl-Di-Ethoxy-Silane), Dimethyldiethoxysilane (Di-Methyl-Silane) Ethoxy-Silane), tetramethylcyclotetrasiloxane (Tetra-Methyl-Cyclo-Tetra-Siloxane), and At least one of octamethylcyclotetrasiloxane (Octa-Methyl-Cyclo-Tetra-Siloxane) can be used.

  The porogen component forming gas is at least one of methane, ethylene, propylene, alpha-terpinene, gamma-terpinene, and limonene. Can be used.

In the above embodiment, the SiOC film is formed by the CVD method, but the forming method is not limited to this. For example, a SOD (spin on dielectric coating) method in which a thin film is formed by spin-coating a solution containing a porogen material and performing heat treatment is also suitable. As a material for the low dielectric constant insulating film formed by the SOD method, for example, methyl silsesquioxane (MSQ) can be used. In addition to MSQ, for example, a film having a siloxane skeleton such as polymethylsiloxane, polysiloxane, and hydrogensilsesquioxane, and an organic resin such as polyarylene ether, polybenzoxazole, and polybenzocyclobutene are the main components. The film may be formed using at least one selected from the group consisting of a porous film and a porous film such as a porous silica film. In the SOD method, for example, a film is formed by a spinner, and this wafer is baked on a hot plate in a nitrogen atmosphere to form a SiOC film containing, for example, organosiloxane containing a porogen material uniformly as a main skeleton component. can do. Regardless of which material of the low dielectric constant insulating film is used, a low dielectric constant having a relative dielectric constant of less than 2.5 can be finally obtained.
Regarding the method for forming the porous structure as described above, for example, JP-A-2009-194072 can be referred to.

In the present invention, the insulating material layer is preferably a polymer of the silsesquioxane compound represented by the following general formula (1).
(RSiO _1.5) a ··· formula (1)

In formula (1), R represents an organic group each independently, and at least two of R represent a polymerizable group. A plurality of R may be the same or different. However, a polymerizable group derived from the cage silsesquioxane compound may remain in the polymer, and usually takes a form in which a polymerizable group remains.
In formula (1), a represents an integer of 8 to 16. a is more preferably an integer of 8, 10, 12, 14 or 16. It is preferable that a is 8, 10, and 12 from the point which the film | membrane obtained has the more excellent low refractive index property and heat resistance, and 8 is more preferable from a viewpoint of superposition | polymerization controllability.

  As a suitable aspect of the said cage silsesquioxane compound, the compound represented by the following general formula (Q-1)-general formula (Q-7) is mentioned. Among these, from the viewpoints of availability, polymerization controllability, and solubility, the compound represented by General Formula (Q-6) is most preferable.

  (In General Formula (Q-1) to General Formula (Q-7), each R independently represents an organic group. In each of General Formula (Q-1) to General Formula (Q-7), R represents At least two of them represent polymerizable groups.)

Examples of the organic group for R include a polymerizable group and a non-polymerizable group.
The polymerizable group is not particularly limited and includes a radical polymerizable group or a cationic polymerizable group. More specifically, cationically polymerizable groups such as epoxy groups, oxetanyl groups, oxazolyl groups, vinyloxy groups, alkenyl groups, alkynyl groups, acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, vinyl ethers, vinyl esters, etc. A radical polymerizable group is preferred. Of these, a radical polymerizable group is preferable and an alkenyl group or an alkynyl group is more preferable from the viewpoint that synthesis is easy and the polymerization reaction proceeds favorably.

In addition, as an alkenyl group, the group which has a double bond in the arbitrary positions of an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group, and a silicon atom containing group is mentioned, for example. Especially, C2-C12 is preferable and C2-C6 is more preferable. For example, a vinyl group, an allyl group, etc. are mentioned, and a vinyl group is preferable from the viewpoint of ease of polymerization control and mechanical strength.
Examples of the alkynyl group include a group having a triple bond at an arbitrary position of an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group, or a silicon atom-containing group. Especially, C2-C12 is preferable and C2-C6 is more preferable. From the viewpoint of ease of polymerization controllability, an ethynyl group is preferred.

  The non-polymerizable group refers to a group that does not have the above-described polymerizability, and specifically includes an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group, a silicon atom-containing group, or a combination thereof. Group and the like. Among these, an alkyl group or a cycloalkyl group is preferable from the viewpoint that the photosensitive film exhibits excellent developability and the obtained pattern film exhibits excellent low refractive index and heat resistance.

The alkyl group may have a substituent, and is preferably a linear or branched alkyl group having 1 to 20 carbon atoms. The alkyl chain may have an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom. Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-dodecyl group, n-tetradecyl group, n Examples include linear alkyl groups such as -octadecyl group, branched alkyl groups such as isopropyl group, isobutyl group, t-butyl group, neopentyl group, and 2-ethylhexyl group.
In addition, as one of the preferable aspects of an alkyl group, the alkyl group which has a fluorine atom (fluorinated alkyl group) is preferable from the point that the film | membrane obtained has a lower refractive index property. Examples of the fluorinated alkyl group include those in which part or all of the hydrogen atoms of the alkyl group are substituted with fluorine atoms. Specific examples include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, and a nonafluorobutyl group.

  The cycloalkyl group may have a substituent, preferably a cycloalkyl group having 3 to 20 carbon atoms, may be polycyclic, and may have an oxygen atom in the ring. Specific examples include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group.

  The aryl group may have a substituent and is preferably an aryl group having 6 to 14 carbon atoms, and examples thereof include a phenyl group and a naphthyl group.

  The aralkyl group may have a substituent and is preferably an aralkyl group having 7 to 20 carbon atoms, and examples thereof include a benzyl group, a phenethyl group, a naphthylmethyl group, and a naphthylethyl group.

  As an alkoxy group, it may have a substituent, Preferably it is a C1-C20 alkoxy group, for example, a methoxy group, an ethoxy group, a propoxy group, n-butoxy group, pentyloxy group, hexyloxy Group, heptyloxy group and the like.

The silicon atom-containing group is not particularly limited as long as silicon is contained, but a group represented by the general formula (2) is preferable.
_{^{* -L 1 -Si- (R 20)}} 3 ··· formula (2)
In general formula (2), * represents a bonding position with a silicon atom. L1 represents an alkylene group, —O—, —S—, —Si (R ²¹ ) (R ²² ) —, —N (R ²³ ) —, or a divalent linking group obtained by combining these. L ¹ is preferably an alkylene group, —O—, or a divalent linking group obtained by combining these.
As an alkylene group, C1-C12 is preferable and C1-C6 is more preferable. R ²¹ , R ²² , R ²³ and R ²⁰ each independently represents an alkyl group, a cycloalkyl group, an aryl group or an alkoxy group. The definitions of the alkyl group, cycloalkyl group, aryl group and alkoxy group represented by R ²¹ , R ²² , R ²³ and R ²⁰ are the same as those defined above, preferably a methyl group, an ethyl group, a butyl group, Examples include a cyclohexyl group.
As the silicon atom-containing group, a silyloxy group (trimethylsilyloxy, triethylsilyloxy, t-butyldimethylsilyloxy) is preferable.

The cage silsesquioxane compound represented by the formula (1) is preferably represented by the following average composition formula (3) _{.
^{(R 1 SiO 1.5) x (}} R 2 SiO 1.5) y ··· Equation (3)
(In the formula (1), R1 is .R ² representing the polymerizable group denotes a non-polymerizable groups. Here polymerizable group, non-polymerizable group is as defined above .x is 2.0 1 represents a number of 14.0 (2.0 ≦ x ≦ 14.0), and y represents a number of 0 to 14.0 (0 ≦ y ≦ 14.0), where x + y = 8 to 16 is satisfied. The plurality of R ¹ and R ² may be the same or different.

In formula (3), x represents a number of 2.0 to 14.0, and x is 2. from the point that the obtained film exhibits more excellent low refractive index property, heat resistance, light resistance, and curability. 5 or more is preferable and 3.0 or more is more preferable.
In the formula (3), y represents a number of 0 to 14.0, and y is preferably 0 to 12.0 from the viewpoint that the obtained film exhibits more excellent low refractive index properties, heat resistance and coating properties. 0-10.0 are still more preferable, 0-7.5 are more preferable, and 0-5.0 are the most preferable.

In the formula (3), x + y = 8 to 16 is satisfied, and x + y = 8 to 14 is preferable from the viewpoint that the resulting film exhibits more excellent low refractive index, heat resistance, hygroscopicity, and storage stability, and x + y = 8-12 are more preferable and x + y = 8-10 is still more preferable.
Furthermore, in the formula (3), the ratio of x (x / x + y) preferably satisfies 0.1 ≦ (x / x + y) ≦ 1.0, and the resulting film has a better low refractive index property and heat resistance. In view of mechanical strength, 0.2 ≦ (x / x + y) ≦ 1.0 is more preferable, and 0.3 ≦ x / y ≦ 1.0 is still more preferable.

<Preferred embodiment of silsesquioxane>
As a preferred embodiment of the silsesquioxanes, x is in the range of 2.0 ≦ x ≦ 8.0 in the formula (3) from the viewpoint that the obtained film exhibits better low refractive index and heat resistance. (Preferably 3.0 ≦ x ≦ 8.0), y represents a number in the range of 0 ≦ y ≦ 6.0 (preferably 0 ≦ y ≦ 5.0), and x + y = 8 And silsesquioxanes composed of a cage silsesquioxane compound represented by the general formula (Q-6).
The silsesquioxanes are composed of one or more cage silsesquioxane compounds (T8 type) represented by the general formula (Q-6). For example, a mixture of a cage silsesquioxane compound having 8 polymerizable groups and a cage silsesquioxane compound having 4 polymerizable groups and 4 non-polymerizable groups may be used.

In another preferred embodiment of the silsesquioxane, in formula (3), x represents a number in the range of 2.0 ≦ x ≦ 10.0 (preferably 3.0 ≦ x ≦ 10.0), and y is A cage-shaped silsesquioxane compound represented by a number in the range of 0 ≦ y ≦ 8.0 (preferably 0 ≦ y ≦ 7.0), x + y = 10 and represented by the above general formula (Q-2) And / or silsesquioxanes composed of a cage silsesquioxane compound represented by formula (Q-7).
The silsesquioxanes are composed of one or more kinds of cage silsesquioxane compounds (T10 type) represented by the above general formula (Q-2) or general formula (Q-7). The

  In another preferred embodiment of the silsesquioxane, in formula (3), x represents a number in the range of 2.0 ≦ x ≦ 12.0 (preferably 3.0 ≦ x ≦ 12.0), and y is A cage-shaped silsesquioxane compound represented by a number in the range of 0 ≦ y ≦ 10.0 (preferably 0 ≦ y ≦ 9.0), x + y = 12, and represented by the above general formula (Q-1) And / or silsesquioxanes composed of a cage silsesquioxane compound represented by the general formula (Q-3). The silsesquioxanes are composed of one or more kinds of cage silsesquioxane compounds (T12 type) represented by the above general formula (Q-1) or general formula (Q-3). The

In another preferred embodiment of the silsesquioxane, in formula (3), x represents a number in the range of 2.0 ≦ x ≦ 14.0, and y represents a number in the range of 0 ≦ y ≦ 12.0. X + y = 14, and silsesquioxanes composed of a cage silsesquioxane compound represented by the general formula (Q-4).
The silsesquioxanes are composed of one or more cage silsesquioxane compounds (T14 type) represented by the above general formula (Q-4).

As another preferred embodiment of the silsesquioxane, a cage silsesquioxane compound having at least three polymerizable groups and at least three non-polymerizable groups (hereinafter also referred to as compound (A)). And silsesquioxanes. That is, the compound (A) is a compound in which at least three of R in the formula (3) represent a polymerizable group, and at least three of R represent a non-polymerizable group. By containing the compound (A), a pattern film having a lower refractive index and excellent heat resistance can be obtained.
In this form, the cage silsesquioxane compound (A) may have three or more polymerizable groups and three or more non-polymerizable groups.
Although the structure of a compound (A) is not specifically limited, It is preferable that it is a compound represented by the general formula (Q-1)-general formula (Q-7) mentioned above.
For example, in the compound represented by the general formula (Q-6), a compound having 3 to 5 polymerizable groups and 3 to 5 non-polymerizable groups and the total number of both being 8 is compound (A). It corresponds to.
Moreover, in the compound represented by general formula (Q-2) or general formula (Q-7), it has 3-7 polymeric groups and 3-7 nonpolymerizable groups, and the total of both is The compound which is 10 corresponds to the compound (A).
In addition, in the compound represented by the general formula (Q-4), a compound having 3 to 11 polymerizable groups and 3 to 11 non-polymerizable groups, and the total number of both is 14 (A )

  The content of the above-mentioned compound (A) in all silsesquioxanes is not particularly limited, but is 10 mol% or more based on the total amount of silsesquioxanes based on the total silsesquioxane points of the obtained film. It is preferably 20 to 100 mol%, more preferably 60 to 100 mol% or more. In particular, it is preferable that the silsesquioxane is composed only of the compound (A) and does not substantially contain other cage silsesquioxane compounds.

The silsesquioxanes described above are usually composed of a cage silsesquioxane compound, but other polysiloxane compounds (ladder-type silsesquioxane compounds, etc.) as long as the effects of the present invention are not impaired. ) May be included.

  Although the specific example of silsesquioxane is shown below, this invention is not limited to these. In addition, the substituent ratio in Table 1 corresponds to x / y in Formula (3).

  The cage silsesquioxane compound used in the present invention may be one that can be purchased from Aldrich, Hybrid Plastics, Polymers, 20, 67-85, 2008, Journal of Inorganic and Organometallic Polymers, 11 (3), 123-154, 2001, Journal of Organometallic Chemistry, 542, 141-183, 1997, Journal of Macromolecular Science A. Chemistry, 44 (7), 659-664, 2007, Chem. Rev., 95, 1409 -1430, 1995, Journal of Inorganic and Organometallic Polymers, 11 (3), 155-164, 2001, Dalton Transactions, 36-39,2008, Macromolecules, 37 (23), 8517-8522, 2004, Chem. Mater., 8, 1250-1259, 1996 or the like.

[Application of backfill polymer]
In this embodiment, as shown in steps (b) and (c) of FIG. 1, the backfilling polymer 3 is applied to the initial porous insulating film 10. 10 ′ refers to the state where the backfill polymer was applied. 10 ″ indicates a state in which the covering layer 32 is removed. Although the application method of the backfill polymer 3 is not particularly limited, a general coating method can be used in this type of device. By this application, a backfill polymer coating layer 32 and a backfill polymer filling hole 31 in which the pores are filled are formed on the insulating material layer. Thereby, the backfill polymer coating / filling insulating material film 10 ′ or its filling film 10 ″ can realize extremely high mechanical strength as compared with the initial porous insulating film 10 having a porous structure. The mechanical strength is preferably 5 GPa or more for device reliability.

  In the present embodiment, not only is the hole 1 in the insulating material layer 2 filled with the filler (backfill polymer filling hole 31), but the coating layer 32 made of the filler polymer is formed thereon. The thickness t of the coating layer 32 is not particularly limited, but is preferably 0.005 to 0.5 μm, and more preferably 0.02 to 0.2 μm. By providing the coating layer made of the filler polymer in this way, it is possible to suppress the generation of voids caused by the formation of volatile pores that are somewhat derived from volatilization, which occurs somewhat even under mild conditions such as room temperature.

Examples of the backfill polymer include polyvinyl aromatic compounds (polystyrene, poly α-methyl styrene, polyvinyl pyridine, halogenated polyvinyl aromatic compounds, etc.), polyacrylonitrile, polyalkylene oxide (polyethylene oxide, polypropylene oxide, etc.), polyethylene, poly Lactic acid, polysiloxane, polycaprolactone, polycaprolactam, polyurethane, polymethacrylate (such as polymethyl methacrylate) or polymethacrylic acid, polyacrylate (such as polymethyl acrylate) and polyacrylic acid, polydiene (such as polybutadiene and polyisoprene), polyvinyl chloride , Polyacetals, and amine capped alkylene oxides, other polyphenylene oxides, poly (di Chill siloxane), polytetrahydrofuran, poly cyclohexyl ethylene, polyethyl oxazoline, polyvinyl pyridine, and poly caprolactone. Among these, polyvinyl aromatic compounds, polyalkylene oxides, polymethacrylates, and polyacrylates are preferable, and polystyrene, poly α-methyl styrene, a copolymer of α-methyl styrene and styrene, and polymethyl methacrylate are more preferable.
Moreover, the boiling point or decomposition temperature of the backfill polymer is preferably 100 to 500 ° C, more preferably 200 to 450 ° C, and particularly preferably 250 to 400 ° C. As molecular weight, it is 50000 or less, it is preferable that it is 200-50000, More preferably, it is 300-10,000, Most preferably, it is 400-5000. That is, the filler may be positioned as an oligomer rather than a typical polymer.

In the present invention, the term “molecular weight” means a mass average molecular weight unless otherwise specified, and the molecular weight and the degree of dispersion are values measured by the following measuring methods. In addition, the mass average molecular weight may be abbreviated as MwXXXX.
[Measurement method of molecular weight and dispersity]
The molecular weight and degree of dispersion are measured using GPC (gel filtration chromatography) unless otherwise specified. The gel packed in the column used in the GPC method is preferably a gel having an aromatic compound as a repeating unit, and examples thereof include a gel made of a styrene-divinylbenzene copolymer. It is preferable to use 2 to 6 columns connected together. Examples of the solvent used include ether solvents such as tetrahydrofuran and amide solvents such as N-methylpyrrolidinone, but ether solvents such as tetrahydrofuran are preferred. The measurement is preferably performed at a solvent flow rate in the range of 0.1 to 2 mL / min, and most preferably in the range of 0.5 to 1.5 mL / min. By performing the measurement within this range, the apparatus is not loaded and the measurement can be performed more efficiently. The measurement temperature is preferably 10 to 50 ° C, most preferably 20 to 40 ° C.

Specific conditions for molecular weight measurement are shown below.
Apparatus: HLC-8220GPC (manufactured by Tosoh Corporation)
Detector: Differential refractometer (RI detector)
Pre-column: TSKGUARDCOLUMN MP (XL)
6mm x 40mm (manufactured by Tosoh Corporation)
Sample side column: The following two columns are directly connected (all manufactured by Tosoh Corporation)
・ TSK-GEL Multipore-HXL-M 7.8mm × 300mm
Reference side column: Same as sample side column Temperature chamber temperature: 40 ° C
Moving bed: Tetrahydrofuran
Sample-side moving bed flow rate: 1.0 mL / min Reference-side moving bed flow rate: 0.3 mL / min Sample concentration: 0.1% by weight
Sample injection volume: 100 μL
Data collection time: 16 minutes to 46 minutes after sample injection Sampling pitch: 300 msec

[Removal of backfill polymer]
In the present invention, the backfill polymers you removed as follows.
As a method for removing the above backfill polymers, removal by heating, removal by solvents, or, Ru combine these methods for removal.
As the heat treatment, a hot plate or a clean oven can be used. The heating temperature is preferably 100 to 500 ° C, more preferably 200 to 450 ° C, and particularly preferably 250 to 400 ° C.
As the solvent, a general organic solvent or solution can be used. Alcohol solvents such as water, methanol, ethanol, 2-propanol, 1-butanol, 2-ethoxymethanol, 3-methoxypropanol, 1-methoxy-2-propanol, acetone, acetylacetone, methyl ethyl ketone, methyl isobutyl ketone, 2-pentanone , Ketone solvents such as 3-pentanone, 2-heptanone, 3-heptanone, cyclopentanone, cyclohexanone, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, ethyl propionate, propyl propionate, butyl propionate , Ester solvents such as isobutyl propionate, propylene glycol monomethyl ether acetate, methyl lactate, ethyl lactate, γ-butyrolactone, tetrahydrofuran, diisopropyl ether, dibutyl Ether solvents such as ether, ethylpropyl ether, anisole, phenetol, veratrol, aromatic hydrocarbon solvents such as mesitylene, ethylbenzene, diethylbenzene, propylbenzene, t-butylbenzene, cumene, N-methylpyrrolidone, dimethylacetamide, etc. Examples thereof include amide solvents, and these may be used alone or in admixture of two or more.
More preferably, with water, 1-methoxy-2-propanol, propanol, acetylacetone, cyclohexanone, propylene glycol monomethyl ether acetate, butyl acetate, methyl lactate, ethyl lactate, γ-butyrolactone, tetrahydrofuran, anisole, mesitylene, t-butylbenzene Particularly preferred are water, cyclohexanone, propylene glycol monomethyl ether acetate, butyl acetate, and tetrahydrofuran.
Furthermore, a high energy beam may be used, and an electron beam or ultraviolet light can be used.
Filled polymer 3 is a layer of film (32), Ru with removal by solvent. Filled polymer 3 in the film (31) is removed by heating, removal by solvents, or its combination.
According to the porous insulating film of this embodiment and the manufacturing method thereof, the removability of the backfill polymer is extremely good. Since this removability is good, it is possible to suitably cope with the manufacture of a high-quality low-k film without significantly increasing the load on the manufacturing process and without significantly affecting the quality of the semiconductor. .

When removing the filler with a solvent, removal of the filler of the polymer coating layer from the filler and backfilled air hole, row by different solvents. When using a different solvent, it is preferable to use water or cyclohexanone as the first solvent for mainly removing the polymer coating layer derived from the filler. Tetrahydrofuran is preferably used as the second solvent for removing the filler in the pores mainly backfilled thereafter.

[Via and wiring formation]
In the above-described embodiment, it is preferable to perform a process of disposing the vias or the wirings 4 at the stage of the insulating material film 10 ′ (step b) to 10 ′ (step c) filled and coated with the backfill polymer (FIG. 2). As described above, the insulating material film 10 ′ to 10 ″ filled and coated with the backfill polymer has the mechanical strength of the insulating material layer 2 greatly increased compared to the initial insulating material film 10 having a porous structure. ing. Therefore, it is preferable in that it is not easily damaged by the above processing. In particular, when a low-k film with a higher porosity is used to increase the dielectric constant than before, the film itself may be damaged during such processing, affecting the product quality. According to the present embodiment, it is possible to perform processing without particularly damaging the insulating material layer, suitably corresponding to the production of the insulating material layer having such a high porosity. In particular, the wall 4a of the via or the wiring 4 tends to have a vacant hole 1 exposed and a fragile and easily damaged surface shape. This is because the backfill polymer made of a specific material is filled here. It can be effectively suppressed.

[Manufacture of semiconductor substrates]
As a more specific manufacturing process of a semiconductor substrate, as known to those skilled in the art, a manufacturing process known as “dual damascene” can be cited. For example, Japanese Patent Application Laid-Open No. 2009-194072 can be referred to. .
The dual damascene technique is usually performed by etching one columnar hole (or via) and groove in an interlayer insulating film (ILD). Thereafter, both structures are filled with copper and a wiring material such as copper is applied thereafter. As a result, a vertical copper via connection structure is formed. Also, in a dual damascene process, the trench or the via can be etched first.

More specifically, an etching stop layer made of silicon nitride (SiN) or silicon carbide (SiC) is provided above an interlayer insulating film, a metal wiring portion, etc., and a porous layer is formed on the etching stop layer. An ultra low-k dielectric layer is provided. This corresponds to the porous insulating film 20 described above. In addition, an insulating layer (typically SiO ₂ ) and a hard mask layer (typically TiN) are provided above the ultra-low-k dielectric layer. This hard mask layer is initially provided for patterning. That is, by using the TiN hard mask layer, the line width is defined, and a straight etching profile can be obtained due to the good selectivity of the TiN hard mask layer with respect to ULK. In addition, the hard mask layer acts as a CMP stop layer during subsequent copper polishing.

  At this time, a photoresist layer may be deposited on the hard mask layer and patterned by lithography, and then the via 4 and a wiring filled with a conductor may be formed. This corresponds to the via 4 in FIG. 2 or the wiring disposed there. At this time, a plurality of photoresist layers may be provided and processed into an arbitrary shape and depth. In this embodiment, the depth is up to the etching stop layer. The via can be filled with a polymer material to create a polymer coating layer or a polymer backfill condition as described above with reference to FIGS. Thereafter, CMP may be performed to create a wiring structure.

  In the above description, the porous insulating film of the present invention has been described based on an embodiment especially assuming the production of a low-k film. However, the present invention is not limited to this, and can be suitably employed for applications useful as a porous insulating film.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention should not be construed as being limited thereto.

  In accordance with the process procedure described in FIG. 1, an insulating material layer (Low-k film) was formed, filler was applied, etching, and filler was removed. The materials described in Table 2 below were used. Each item was evaluated as follows.

<Fillability evaluation>
The amount of carbon in the film thickness before and after filling the insulating film was analyzed by a technique using an etching escalator (apparatus: PHI Quantera SXMTM [trade name]). The results were classified and evaluated as follows.
○: Increased by 10% or more in all film thickness directions ×: Other than that

<Roughness evaluation after etching>
The surface of the film after complete removal etched with a CF ₄ gas system (apparatus: Hitachi High-Technologies U-621 [trade name]) was observed by SEM.
○: No change from the film before filling ×: Surface roughness is visually observed

<Heat resistance evaluation>
Evaluation was performed using SDT Q600 [trade name] manufactured by TA Instruments. Evaluation temperature was 250 degreeC and the change of the mass at that time was measured. It means that heat resistance is so high that this reduction amount is small.

The notation in the table is supplemented below.
Compound A: T-8 system: Exemplified Compound I-32 (forms an initial porous insulating material film so that k value = 2.35, mechanical strength E = 8.0 GPa)
Compound B: T-8 system: Exemplified Compound I-32 (forms an initial porous insulating material film so that k value = 2.2, mechanical strength E = 7.0 GPa)
Compound C: Part of the vinyl group is methyl ... Exemplified Compound I-13 (forms an initial porous insulating material film so that k value = 2.2, mechanical strength E = 6.0 GPa)

BA: Butyl acetate CB: Chlorobenzene

A1: Polystyrene Mw800
A2: Polystyrene Mw2400
A3: Polystyrene Mw 60000
B: α-methylstyrene / polystyrene copolymer Mw 8000
C: Polyethylene oxide PE-3100 (manufactured by BASF)
D: Polymethylmethacrylate Mw2000
E: Poly α-methylstyrene Mw10000
I: POSS compound II: A to F above

CH: cyclohexanone THF: tetrahydrofuran FNC: (furnace cure: heating under nitrogen gas)

Δn1: The difference in film refractive index “after removal of the upper layer and before filling” Δn1 is preferably 0.1 or more, using a VUV-VASE ellipsometer manufactured by JA Woollam

Δn2: The difference in film refractive index between “after complete removal and before filling” Δn2 is preferably 0.025 or less using a VUV-VASE ellipsometer manufactured by JA Woollam

  As is clear from the above results, according to the porous insulating film of the present invention and the manufacturing method (Example) thereof, the low dielectric constant and mechanical strength of the insulating film were maintained without requiring any particularly complicated operation. It can be seen that the etching damage can be improved.

DESCRIPTION OF SYMBOLS 1 Hole 2 Insulating material layer 3 Backfill polymer 31 Backfill polymer filling hole 32 Backfill polymer coating layer 4 Via or wiring 4 Via or wiring wall part 10 Initial porous insulating material film 10 'Covering and filling with backfill polymer Insulating Material Film 10 '' Insulating Material Film 20 Filled with Backfill Polymer Porous Insulating Film (Porous Insulating Material Film With Backfill Polymer Removed)

Claims (5)

(1) Step of forming a porous insulating film from a composition containing a compound having a siloxane structure (2) Applying a filler to the porous insulating film to refill the porous portion, and forming an upper layer of the porous insulating film A step of forming a polymer coating layer derived from a filler (3) a step of removing a polymer coating layer derived from a filler and removing a filler in the backfilled pores. It is a manufacturing method of a film | membrane, Comprising: The manufacturing method of the porous insulating film which performs the process of at least any one of following (a)-(c) in the said process (3).
(A) The polymer coating layer derived from the filler and the filler in the backfilled pores are removed with different solvents.
(B) The polymer coating layer derived from the filler is removed with a solvent, and the filler in the backfilled pores is removed by heating.
(C) The polymer coating layer derived from the filler is removed by a solvent, and the filler in the backfilled pores is removed by heating and a solvent different from the removal solvent of the polymer coating layer.   2. The method for producing a porous insulating film according to claim 1, wherein a polymer having a molecular weight of 50,000 or less is used as the filler. The compound having a siloxane structure is a polymer obtained from silsesquioxanes composed of one or more cage silsesquioxane compounds represented by the following formula (1): The method for producing a porous insulating film according to claim 1 or 2.
_(RSiO 1.5) a ··· formula (1)
(In formula (1), R represents an organic group each independently, and at least 2 of R represents a polymeric group. A represents an integer of 8 to 16. Several R are the same. However, a polymerizable group derived from the cage silsesquioxane compound may remain in the polymer.) The said cage silsesquioxane compound is 1 type or 2 chosen from the group which consists of a cage silsesquioxane compound represented by either of the following general formula (Q-1)-general formula (Q-7) The method for producing a porous insulating film according to claim 3, wherein the method is a seed or more.

(In General Formula (Q-1) to General Formula (Q-7), each R independently represents an organic group. In each of General Formula (Q-1) to General Formula (Q-7), R represents At least two of them represent polymerizable groups.)   The method for producing a porous insulating film according to claim 1, further comprising a step of forming a wiring or a via after the step (2).

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