JP5019178B2 - Process for removing and / or curing porogen using ultraviolet light to form porous low-k dielectric - Google Patents

Description

  The present disclosure relates generally to the manufacture of semiconductor devices, and more particularly to removing and / or curing porogens using ultraviolet light to form porous low-k dielectrics used in semiconductor devices. About the process.

As semiconductor devices and other microelectronic devices are innovatively reduced in size, the demands on such devices continue to increase. For example, preventing capacitive crosstalk between interconnect lines becomes much more critical as devices get smaller. Capacitive crosstalk is generally a function of both the distance between conductors and the dielectric constant (k) of the material (ie, insulator) placed between the conductors. Considerable interest has been devoted to electrically insulating the conductors from one another while using new insulators with low dielectric constants. Although silica (SiO ₂ ) has traditionally been used in the device due to its relatively low dielectric constant of about 4 and has met the requirements of applications earlier (ie, larger), this silica has dimensions It is not appropriate for reducing the scale (scale down).

  In order to achieve a low dielectric constant, one chooses either (or both) to use a material with an inherently low dielectric constant and / or to introduce porosity into the material. It is possible. The latter effectively lowers the dielectric constant. This is because the dielectric constant of air is nominally 1. Porosity has been introduced into low-k materials through various means. For spin-on, low-k dielectrics, lowering the k-value can be achieved by using a high-boiling solvent, by using a template (empirical data), or by a porogen-based method. Is possible. However, it has proven to be generally difficult to integrate porous low-k materials in the manufacture of semiconductor devices.

  One major issue with low-k dielectrics based on porogens is the use of porogens to create pores without adversely affecting non-dielectric materials or other components within the semiconductor device. The difficulty with removing. A very large number of such methods are used at temperatures above 300 ° C. to cross-link films (thin films), decompose and / or remove volatile porogen elements, and lower the dielectric constant of the films. Requires a thermal cure process with a duration of 30 minutes or more. The above temperature will exceed the heat capacity that is acceptable for manufacturing the device. Further, when pores are introduced into the dielectric material in the above embodiment, the mechanical force of the entire porous dielectric material can be weakened. In addition to affecting the thermal and mechanical properties, the porous dielectric material thus cured has a relatively low etch resistance, and where improvements are generally desired. It has the area of.

  As a result, other cure techniques and process flows have evolved in attempts aimed at such integration. For example, in a process of forming a porous, low-k dielectric from a porogen-based material, vacuum ultraviolet (VUV) light or ultraviolet (UV) light combined with an oxygen-containing atmosphere is generated inside the dielectric material. Have been used alternately for thermal curing processes to make holes. However, these techniques chemically modify non-porogenic elements of the dielectric material, thereby degrading or even destroying the resulting film.

  Other major issues facing the integration of porous low-k materials are chemical mechanical polishing (CMP), plasma etching, wet processing, diffusion barrier layer deposition, interconnect line deposition, plasma ashing, and chemistry, among others. How to make a hole while providing a structure that can withstand other processing steps, such as processing or heat treatment. If reactive chemicals and solvents in contact with the abrasive or the like penetrate into the pores during continuous processing, the dielectric film (dielectric thin film) deteriorates, the dielectric constant increases, and / or the subsequent manufacturing steps. It is possible to leave a residue that can further adversely affect the process. Many prior art methods provide a cap (cover means) to a porous dielectric film layer while using one or more thin, non-perforated dielectric films during device manufacture. Trying to overcome the above problems. For example, it not only improves the lithography process by providing reflection control and / or added etch selectivity, but also protects the surface of the porous film layer against damage from continuous processes such as CMP. . In the harsh chemical process following CMP, the dielectric material is further degraded or increased in dielectric constant when reactive gases and / or solvents penetrate the porous film. Furthermore, the addition of a layer of cap increases the complexity of the device, increases the effective k value, adds additional processing processes, and increases manufacturing costs. This is generally undesirable as the device scales to smaller shapes.

  Thus, low-k candidates that provide success are required to exhibit some critical material properties. For example, chemical resistance to oxidation, plasma ashing, moisture absorption during stripping and cleaning, CMP treatment, ie thermal stability [(no weight loss or repeated isothermal soak at eg 400 ° C.] And properties such as the ability to adhere to substrates including liners and barriers to withstand shear forces and delamination forces that can be generated by CMP processing.

  Therefore, there is a need in the art to provide improved methods for the fabrication of porous low-k dielectric materials for semiconductor device integration. At least because of the problems described in the prior art, the film is chemically treated so that the method affects the physical and mechanical properties of the dielectric layer or other device elements during porogen removal. If not modified, the method is desirable. If the method is more preferred for the heat capacity, it will be more desirable. It would be even more beneficial if the method of reducing integration was done in connection with low k dielectric materials.

Here, a process for porogen removal and / or cure using ultraviolet light to form porous low-k dielectric materials and electrical interconnect structures in a semiconductor device is disclosed. The process of the present invention deposits a low-k dielectric material comprising a matrix and a porogen material on a substrate and exposes the low-k dielectric material to a first ultraviolet radiation pattern having a wavelength longer than 240 nanometers. The first ultraviolet irradiation pattern increases the cross-linking density of the low-k dielectric material, and the concentration of the porogen material is the same before and after exposure to the first ultraviolet irradiation pattern. And patterning the low-k dielectric material and forming a metal interconnect structure in the patterned low-k dielectric material; k dielectric material is exposed to a second UV radiation pattern having a broadband wavelength of less than 240 nanometers to remove the porogen material from the matrix, and porous low k It is characterized by forming a conductor material.

  Another embodiment is a process for removing porogen material from a dielectric layer that includes the porogen material and reducing the dielectric constant, having a broadband illumination pattern that includes a wavelength of less than 240 nanometers over a period of time. Exposing the dielectric layer with an intensity effective to volatilize the porogen material from the dielectric layer upon UV irradiation, flowing a gas around the dielectric layer, and removing the volatilized porogen material , A process comprising reducing the dielectric constant of the dielectric layer.

  Yet another embodiment is a process of forming an electrical interconnect structure, comprising depositing a low-k dielectric material on a substrate. The low-k dielectric material includes a matrix and a porogen material, wherein the low-k dielectric film is exposed to a first ultraviolet irradiation pattern, and the first ultraviolet irradiation pattern is exposed to the low-k dielectric film. Effective to increase the crosslink density, and the porogen material concentration is maintained substantially the same before and after exposure to the first UV irradiation pattern, and the low k Patterning a dielectric material and forming a metal interconnect structure in the patterned low-k dielectric material; and forming the low-k dielectric material substantially from the porogen material. It is a process characterized by exposing to the second ultraviolet irradiation pattern in an amount for effectively removing everything.

  The foregoing description and other features are exemplified by the accompanying drawings and detailed description. These drawings are exemplary embodiments, and like elements are given like numbers.

  The present disclosure is generally directed to a process (manufacturing method) for forming an electrical interconnect structure including a porous low-k dielectric film. The process includes a UV cure process that removes the porogen material from the low-k dielectric film to form a low-k dielectric film. The UV cure process as described in detail below occurs after the formation of the interconnect structure and provides a means for integrating porous low-k dielectric materials within the integrated circuit manufacturing process. . As used herein, the phrase “porous low-k dielectric material” generally includes a matrix and a removable porogen, and the porous after removal of the porogen by a UV process. A dielectric material refers to a material having a dielectric constant (k) of less than 3.0.

  The process of forming the electrical interconnect structure generally includes depositing or coating a layer of low-k dielectric material containing porogen onto the substrate. The layer can then be exposed to the first UV irradiation pattern with an intensity and time effective to increase the crosslink density without first removing a substantial amount of porogen material. The amount of porogen material removed is in a range such that the pore fill ratio is within, for example, plus or minus 20% of the pore fill ratio before processing, while remaining substantially unaffected. It is an amount to do. The layer is then patterned in the process flow using conventional lithography techniques including a hard mask, if desired. The patterned low-k dielectric material is then used for the continuous deposition of copper interconnect structures within vias / trenches provided in the patterned low-k dielectric layer. Typically coated with a barrier / copper seed layer commonly used for this purpose. Next, the substrate is typically subjected to a chemical mechanical polishing (CMP) process to planarize the substrate surface. By maintaining the low-k dielectric layer substantially free of holes, a chemical mechanical polishing (CMP) process that provides planarization has no detrimental effect on the integration. For example, etch selectivity is maintained to minimize the presence of holes. Similarly, because reactive gases and / or solvents cannot penetrate the dielectric film without pores, the harsh chemical processes that follow the CMP process do not degrade the dielectric material or It does not increase the rate.

  The device is then exposed to a second UV radiation pattern, after these processing processes to lead to a low-k dielectric and copper interconnect structure. The device is under strength and time conditions effective to remove substantially all removable porogen material from the low-k dielectric layer, thereby providing a porous low-k dielectric layer. Is made. The dielectric constant obtained for the porous low-k material is effectively reduced as a result of exposing the low-k dielectric material to the second UV radiation pattern.

  Unexpectedly, exposure to the first and second UV irradiation patterns as described above cross-links the low-k dielectric film before patterning (first UV irradiation exposure). And that the exposure can be removed after the formation of the metal interconnect structure (second UV irradiation exposure) without degrading the porous low-k dielectric structure It has been found to be effective in efficiently removing porogen material. In this aspect, the problem noted in the column of the prior art can be solved. For example, cross-linking occurs before patterning the low-k dielectric film, and after successive processing steps required for metallization, until the reactive chemicals and solvent penetrate the holes, Is not substantially formed, so that no contact with the abrasive occurs during chemical mechanical polishing or the like. Furthermore, compared to conventional thermal curing processes for removing porogen material, exposure to UV irradiation patterns does not affect the heat capacity and is generally more efficient. For example, when compared to the amount of porogen remaining after heat removal treatment such as by curing in a furnace, a greater amount of porogen material is removed from the low-k dielectric material upon exposure to the second UV irradiation pattern. It can be removed. In addition to further efficiency improvements, the process time is significantly reduced by using an ultraviolet irradiation process compared to a conventional furnace cure process.

  In other embodiments, a low-k dielectric film is converted into a 180-240 nanometer (nm) broadband UV irradiation pattern in order to effectively remove the porogen material from the low-k dielectric material by UV curing. Including exposing. Unexpectedly, it has been found that this unique wavelength region is more effective than ultraviolet irradiation with wavelengths longer than 240 nm. As used herein, the phrase “broadband” refers to a wavelength having a FWHM (full width at half maximum) greater than about 10 nanometers. The UV curing process can be performed before and after patterning the dielectric. Thus, the illustrated process for forming an electrical interconnect structure deposits a low-k dielectric film, forms a pattern in the low-k dielectric film, and forms a metal interconnect. And exposing the substrate to a broadband ultraviolet irradiation pattern having a wavelength of 180 nm to 240 nm. In this manner, the low-k dielectric film is made porous after formation of the metal interconnect processing process.

  In yet other embodiments, porogen removal and cross-linking are performed simultaneously. The UV irradiation pattern is selected to both remove the porogen and increase the crosslink density of the low-k dielectric material. In one embodiment, suitable UV exposure for porogen removal and cross-linking occurs in the manner described above after formation of the interconnect structure.

  As used herein, the phrase “porous low-k dielectric” generally includes a porogen material that can be removed by UV radiation and a matrix or matrix precursor, and is deposited or coated. Point to. Various methods of deposition and / or coating are well known to those skilled in the art, and the means are used by themselves or in combination. Some examples of processes that can be used to form a low-k dielectric film are chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), high density chemical vapor deposition (PECVD), photon Excitation CVD, plasma photon excitation CVD, cryogenic CVD, chemically accelerated deposition, hot filament CVD, CVD of liquid polymer precursors, deposition from supercritical fluids, or transport polymerization (TP). Other processes that can be used to form the film include spin coating, dip coating, Langmuir-blodgett self-organization, or spray deposition methods.

  As used herein, the phrase “porogen material” refers to sacrificial organics known to those skilled in the art that generate or form pores within the low-k dielectric film after removal of the porogen. Refers to the base material. The porogen material forms domains or individual regions in the matrix or matrix precursor and forms pores in the matrix or matrix precursor by removal. Preferably, the area should be less than or equal to the final desired pore size. In the present disclosure, suitable porogen materials are materials that decompose upon exposure to ultraviolet radiation to form volatile residues (fragments) or radicals (excited atoms or atomic bonds). It should be noted that the volatile residues or radicals can be removed from the matrix material or matrix precursor material, for example, under an inert gas flow. In this embodiment, pores are formed within the matrix when exposed to ultraviolet radiation.

  These porogen materials, which are generally characterized in the art as being thermally unstable, thermally removable, etc., are removed upon exposure to the ultraviolet irradiation process described herein. Generally suitable. This type of material is generally described in US Pat. No. 6,653,358, entitled “Composition comprising a crosslinkable matrix precursor, a porogen and a porous matrix prepared therefrom”. Which is hereby incorporated by reference in its entirety.

  Examples of porogen materials that are easily removed when exposed to ultraviolet radiation include, but are not limited to, carbohydrate materials, labile organic groups, solvents, degradable polymers, surfactants, dendrimers, hyperbranched polymers, polyoxyalkylenes A compound, or a combination thereof.

For example, the porogen material is a block copolymer (eg, a diblock polymer). Such materials can be self-assembled if the block is not likely to mix to provide a separation region in the nanometer sized range. Such block copolymers are added to a crosslinkable matrix precursor with or without a solvent to obtain a form suitable for processing. The block copolymer can be self-assembled during processing (eg, after spin coating but before the matrix is formed). One or more of the blocks reacts with the matrix or the blocks do not react. One or more of the blocks may be compatible (compatible) with the matrix or its precursor, but preferably at least one block is compatible (compatible) with the matrix. There is no. Effective polymer blocks include matrix precursors, polyvinyl aromatics such as polystyrenes, 3) polyvinyl pyridines, hydrogenated polyvinyl aromatics, polyacrylonitrile, Polyalkylene oxides such as polyethylene oxide and polypropylene oxide, polyethylene (polyethylenes), polylactic acids (polylactic acids),
Polysiloxanes such as polysiloxanes, polycaprolactones, polycaprolactams, polyurethanes, polyurethanes, polymethylmethacrylate or polymethylmethacrylic acid, polymethylacrylates, polymethyl Polyacrylates such as polymethylacrylate and polyacrylic acid, polydienes such as polybutadienes and polyisoprenes, polyvinyl chlorides, polyacetals, And polymers of amine-capped conjugated oxides crowned (covered) with amine groups.

  For example, diblock polymers based on polystyrene and polymethylmethacrylate preferably have a resin to diblock polymer weight ratio of about 1: 1 or more, more preferably 2: 1 or more, and more preferably 3 :. It can be added to a solution of cycloten (CYCLOTENE®) resin in a suitable solvent, such as mesitylene, by weight to be one or more. Depending on the application (use method), the total solid content is basically about 1% by weight or more, more basically about 5% by weight or more, most basically about 10% by weight, and basically Less than about 70% by weight, more basically less than about 50% by weight, and most basically less than about 30% by weight. The solution can then be spin coated onto a silicon wafer in the continuous phase of the DVS-bisBCB resin, leaving a thin film containing the dispersed phase of the diblock copolymer. The film is then cured by irradiation while including a dispersed phase of cross-linked DVS-bisBCB poly (styrene-b-methyl methacrylate) and leaving a cross-linked polymer system. Is possible. For example, the film can be cured by exposure to a first UV irradiation pattern that effectively cross-links the film. The diblock copolymer can then be decomposed or removed by exposure to ultraviolet radiation to leave a porous cross-linked DVS-bisBCB polymer. Similarly, diblock polymers based on polystyrene and polybutagenone are dicyclopentagenone (eg, 3,3 ′-(oxydi-1,4-ferelene) bis (2,4,5-triphenylcyclopenta). Genone (3,3 '-(oxydi-1,4-phenylene) bis (2, 4,5-triphenycyclpentadienone) and trisacetylene (eg, 1,3,5-tris (phenylethynyl) benzene (1,3,5 -tris (phenylethynyl) benzene)) can be added to b-staged solutions.

  Thermoplastic, homopolymers and messy (as opposed to block) copolymers can also be utilized as suitable porogen materials. As used herein, the phrase “homopolymer” means a composition comprising repeating units from a single monomer. Suitable thermoplastic materials are polystyrenes, polyacrylates, polymethacrylates, polybutadienes, polyisoprenes, polyphenylene oxides, polypropylene oxide, polyethylene Oxides (polyethylene oxides), poly (dimethylsiloxanes), polytetrahydrofurans (polytetrahydrofurans), polyethylene (polyethylenes), polycyclohexylethylenes (polycyclohexylethylenes), polyethyloxazolines (polyethyloxazolines), polyvinylpyridines (polyvinylpyridines) , Polycaprolactones, polylactic acids, copolymers of these materials and mixtures of these materials. The thermoplastic material is inherently linear, branched, hyperbranched, tree-like or star-like.

  Polystyrene is suitable for thermosetting mixtures or b-staged products of polycyclopentadienone and polyacetylene. The polystyrene polymer is decomposed by actinic radiation (by UV irradiation) to become the original monomer, which is then diffused from the matrix. Any of the known polystyrenes can serve as porogens. For example, anionic polymerized polystyrene, syndiotactic polystyrene, unsubstituted polystyrene, and substituted polystyrene (eg, poly (α-methylstyrene)) are all used as porogens.

  For example, anionically polymerized polystyrene having an average molecular weight of 8,500 can be mixed with a polyarylene b-staged reaction product of polycyclopentagenone and polyacetylene. This solution can then be spin coated onto a silicon wafer to produce a thin film comprising a polyarylene matrix precursor with a dispersed phase of polystyrene. The coated wafer can be thermally cured, for example, on a hot plate to form a matrix, or by exposure to ultraviolet radiation, to a temperature below 425 ° C., eg, Polystyrene porogen can be removed by exposure to a suitable UV irradiation pattern to form a porous polyarylene matrix. Removal of the porogen material can occur before or after dielectric patterning, depending on the desired application.

  The porogen is also designed to react with a cross-linkable matrix precursor during or subsequently to b-staging to form a block or pendent replacement of the polymer chain. Thus, a thermoplastic polymer, such as vinyl, acrylate, methacrylate, allyl, vinyl ether, maleimido, styryl, Acetylene, nitrile, furan, cyclopentadienone, perfluoroethylene, BCB, pyrone, propiolate, or ortho-diacetylene ) Groups can form chemical bonds with the crosslinkable matrix, from which the thermoplastic material can be removed, leaving pores. Thermoplastic polymers include polystyrenes, polyacryclates, polymethacrylates, polybutadienes, polyisoprenes, polyphenylene oxides, polypropylene oxides, polyethylene oxides (polyoxides) polyethylene oxides, poly (dimethylsiloxanes), polytetrahydrofurans, polyethylenes, polycyclohexylethylenes, polyethyloxazolines, polycaprolactones, polycaprolactones Homopolymer or copolymer of polylactic acids and polyvinylpyridine, or a mixture thereof, single reactive group or multiple reactions The number and type of reactive groups determine whether the thermoplastic porogen is incorporated into the matrix as a pendant or block material. Specifically, they are linear, branched, hyperbranched, tree-like, or star-like.

  For example, low molecular weight (<10,000 Mn) polypropylene glycol oligomers are end-capped with cinnamate groups and add about 10 to about 30% by weight relative to neat DVS-bisBCB monomer. Can be done. This mixture is then b-staged by heating, diluted with a suitable solvent such as mesitylene, spin coated onto a silicon wafer, and chemically bonded to b-staged DVS-bisBCB. A thin film containing a dispersed phase of a glycol oligomer is prepared. The dispersed polypropylene glycol oligomer can then be decomposed by exposure to a suitable UV irradiation pattern and treatment to leave a porous, cross-linked DVS-bisBCB polymer.

  The desired molecular weight of the polymerized porogen will vary depending on various factors such as compatibility between the matrix precursor and the cured matrix, the desired pore size, and the like. In general, however, the number average molecular weight of the porogen is from about 2,000 to less than about 100,000. The porogen polymer also preferably has a narrow molecular weight distribution.

  Porogens are also substances having an average diameter of about 1 nm to about 50 nm. Examples of such materials include dendrimers where polyamidoamine (PAMAM) dendrimers are available through Dendritech and polypropyleneimine polyamine (DAB-AM) dendrimers are available from DSM. Flehette-type polyether dendrimers, Parsec-type liquid crystal monodendrites, single-resin-like polymers and self-assembled macromolecules, Boltlon H-series resinous polyesters (commercially , Parstop AB is available) and latex particles, especially crosslinked polystyrene containing latex. These materials do not react with the crosslinkable matrix precursors, but react as described above. For example, a second generation PAMAM (polyamidoamine) dendrimer from Dendritech can be functionalized with a vinylbenzyl chloride compound to convert the amine group on the surface of the dendrimer on the surface of the vinylbenzyl group. This functionalized dendrimer can then be added to a b-staged DVS-bisBCB solution in mesitylene. The mixture can then be spin-coated on a silicon wafer to obtain a dispersed phase (dispersed phase) of the PAMAM dendrimer within the DVS-bisBCB oligomer. The film can be thermally cured to obtain a cross-linked polymer system that includes a dispersed phase of PAMAM dendrimer chemically bonded to a continuous phase of cross-linked DVS-bisBCB It is. The dendrimer can then be decomposed by exposure to ultraviolet radiation to obtain a porous cross-linked DVS-bisBCB polymer. Instead, a fourth-generation bolstron dendritic polymer (H40) from Perstorp AB is modified around the benzoyl chloride compound to convert the hydroxy groups on the surface of the dendrimer to phenyl ester groups. It is possible. The functionalized dendrimer is then a partially polymerized (ie, b-staged) reaction product of a polycyclopentagen compound and a polyacetylene compound in a mixture of gamma-butyrolactan and cyclohexanane solvent. It can be added to the precursor solution. The mixture can then be spin-coated on a silicon wafer to obtain a dispersed phase of a benzene dendritic polymer made of Voltron H40 in the precursor oligomer. This membrane can be thermally cured to obtain a crosslinked polymer system. The system includes a dispersed phase of dendrimer chemically bonded to a continuous phase of cross-linked polyarylene. The dendrimer is then decomposed by exposure to an ultraviolet irradiation process to obtain porous cross-linked polyarylene.

  On the other hand, porogens can also be solvents. For example, a b-staged prepolymer or partially cross-linked polymer can first be swollen in the presence of a suitable solvent or gas. This swollen material can then be further cross-linked to improve structural integrity. Suitable solvents include, but are not limited to, mesitylene pyridine, triethylamine, N-methylpyrrolidinone (NMP), methyl benzoate, ethyl benzoate ), Butyl benzoate, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, cyclohexylpyrrolidinone, and ethers or hydroxy ethers ), For example, dibenzylethers, diglyme, triglyme, diethylene glycol ethyl ether, diethylene glycol methyl ether r), dipropylene glycol methyl ether, dipropylene glycol dimethyl ether, propylene glycol phenyl ether, propylene glycol methyl ether, tripropylene Glycol methyl ether, toluene, xylene, benzene, dipropylene glycol monomethyl ether acetate, dichlorobenzene, propylene carbonate, naphthalene, diphenyl ether ( diphenyl ether, butyrolactone, dimethylacetamide, dimethylformamide Comprising a mixture of the benefactor.

  The pore density in the porous matrix is high enough to reduce the dielectric constant of the matrix, but the matrix can be used in any desired microelectronic device (eg, integrated circuit (IC), multichip module or flat panel display device). ) Is sufficiently low to be able to withstand the process steps required for manufacturing. Suitably, it is sufficient to reduce the dielectric constant of the matrix when the density of the pores is less than 3.0, preferably less than 2.5, more preferably less than 2.0. Preferably, the pore density is at least 5% by volume, more preferably at least 10% by volume, most preferably at most 20% by volume and not more than 70% by volume, more preferably based on the total volume of the porous matrix. Is 60% by volume.

  The average diameter of the pores is preferably less than about 400 nm, more preferably less than 100 nm, even more preferably less than 50 nm, more preferably less than 20 nm, and most preferably less than 10 nm.

  Suitable matrices and matrix precursors are generally, but not limited to, polymers containing silicon or precursors to such polymers, such as methyl silsesquioxanes, hydrogenated Hydrogen silsesquioxane, adamantine based thermosetting compositions such as cross-linked polyphenylene, polyaryl ether, Examples thereof include polystyrene, cross-linked polyarylene, polymethylmethacrylate, aromatic polycarbonate, aromatic polyimide, and the like.

Suitable silicon containing compounds generally include silicon, carbon, oxygen, hydrogen atoms, and more commonly referred to as SiCOH dielectrics. Exemplary silicon containing compounds include (i) silsesquioxane, (ii) alkoxysilanes, preferably partially enriched alkoxylanes (eg, tetraethoxylane having a Mn of about 500 to 20,000). Partially concentrated by controlled hydrolysis)), (iii) organically modified silicates with compounds RSiO ₃ and R ₂ SiO ₂ , where R is an organic substituent, and (iv) Orthosilicates, preferably orthosilicates with compound Si (OR) ₄ , preferably partially concentrated orthosilicates with partially concentrated compound Si (OR) ₄ are included. As known to those skilled in the art, silsesquioxanes are (RSiO _1.5 ) n-type polymeric silicate materials where R is an organic substituent. A combination of two or more different silicon containing compounds can also be used.

  Suitable silicon containing compounds are known to those skilled in the art and / or are described in the accompanying text, patents and literature. For example, U.S. Pat. No. 5,384,376 to Tunney et al., U.S. Pat. No. 6,107,357 to Hawker et al., U.S. Pat. No. 6,143,643 to Carter et al., And Chemical Review '95 (Chem. Rev.), pages 1409 to 1430 (published in 1995). Preferably, the silicon containing compound is silsesquioxane. Suitable silsesquioxanes include, but are not limited to, hydrogenated silsesquioxanes, alkyl (preferably low alkyl, eg, methyl) silsesquioxane, allyl (eg, phenyl) or alkyl / allyl silsesquioxane and silsesquioxane. Oxane copolymers (for example, polyimide and silsesquioxane copolymers).

  Other silicon based cyclic siloxanes or dielectric precursors can be transported in the vicinity of the semiconductor where the porogen-containing silicon is also transported. As mentioned above, this can be done through conventional CVD or other deposition methods. In this embodiment, silicon based on a dielectric precursor and silicon containing a porogen are synthesized to form the porogen material described above.

  The organosilicon containing porogen of the porogen material contains thermally cleavable organic groups. In one embodiment, the porogen material is activated by exposure to ultraviolet light to release cleavable organic groups. Such silicon containing porogens include alkyl, fluoroalkyl, perfluoroalkyl, cycloalkyl, allyl, fluoroallyl, vinyl, allyl, or other side chains. In other embodiments, the silicon containing porogen comprises ultraviolet radiation cleavable ultraviolet radiation that is a tertiary alkyl group, such as t-butyl or amyl groups. The special silicon containing porogen used is used to activate compatibility with dielectric precursor based silicon, the size and amount of pores to be formed, and porogenesis. This is a matter related to the selection of the design by factors such as desired parameters.

  Furthermore, silicon based dielectric precursors include, for example, tetramethylcyclotetrasiloxane, hexamethylcyclotetrasiloxane, and octamethylcyclotetrasiloxane.

  One type of matrix precursor includes thermoset benzocyclobutene (BCBS) or its b-staged product. For example, 1,3-bis (2-bicyclo [4.2.0] octa-1,3,5-triene-3-iletinyl) -1,1,3,3-tetramethyldisiloxane (1,3-bis (2-bicyclo [4.2.0] octa-1,3,5-trien-3-ylethynyl) -1,1,3,3-tetramethyldisiloxane) (referred to as DVS-bisBCB). ) Is suitable and the b-staged resin is commercially available as cycloten (CYCLOTENE®).

  Another type (class) of matrix material includes polyarylene. As used herein, the phrase “polyarylene” refers to compounds in the polyarylene ether that are made from repeating arylene units, compounds with a skeleton, or compounds having an arylene unit with other bridging units in the skeleton. Includes compounds with oxygen. Examples of commercially available polyarylene compounds include silk (SiLK®) semiconductor dielectric (Dow Chemical), flare (Flare®) dielectric (Allide Signal), Velox. (Registered trademark)) (polyarylene ether) (air product / manufactured by Schumacher). One class (class) of polyarylene matrix precursors is a thermosetting compound or b-staged product of polycyclopentanone and polyacetylene. Examples of thermosetting or crosslinkable polyarylenes used in the compounds of this invention include monomers. For example, there are aromatic compounds that are substituted with ethenylic at the ortho positions relative to each other in an aromatic ring, and compounds that contain a cyclopentagenone functional group combined with an aromatic acetylene compound and a polyarylene ether. More preferably, the thermosetting compound comprises a partially polymerized reactive compound (ie, a b-staged oligomer) of the aforementioned monomers.

  When the matrix precursor comprises a thermoplastic mixture of polycyclopentadienone and polyacetylene or their b-staged product, the precursor is preferably a curing process. During this period, branching occurs relatively early. An early branched matrix is formed in this cure process to prevent loss of matrix molecules and to minimize possible breakage of the pores during the cure process. One approach to accomplishing this is to have cyclopentadienone functionality and acetylene functionality in the precursor compound, such as greater than 3: 4, preferably 2: 1, more preferably 1: 1. And use the ratio. 3 parts by weight of 3,3 ′ (oxydi-1,4-phenylene) bis (2,4,5-) triphenyl (2-4-5 (triphenylcycle pentagenone (3,3 ′-(oxydi-1 , 4-phenylene) bis (2,4,5-triphenycyclpentadienone) and 2 parts by weight of 21,3,5-tris (phenylethynyl) benzene (more than moles Ratio) is an example of such a system, while an additional reagent capable of cross-linking thermoplastic mixtures or the production of b-staged polycyclopentadienone and polyacetylene Can be added during the curing process to minimize the loss of elastic modulus of the matrix Examples of suitable reagents are bisorthodiacetylenes, monoorthodiacetylenes, bistriazenes ( bistriazenes), tetrazines, such as 1,3-diphenyltetrazine, bisazides, such as bissulfonylazides, and diperoxides Peroxides.

  A third example of a matrix precursor suitable for the preparation of a porous matrix is a thermoplastic perfluoroethylene monomer (having more than two functional groups) or a b-staged product thereof, such as 1 1,1-tris (4-trifluorovinyloxyphenyl) ethane. Thermoplastic perfluoroethylene monomers also conveniently copolymerize with perfluoroethylene having two functional groups. Other suitable polyarylene matrix precursors are thermoplastic bis-o diacetylenes or b-staged products thereof.

  During integrated circuit (IC) fabrication, a low-k dielectric material, including porogen material, is deposited onto a suitable substrate and subjected to an ultraviolet radiation process, for example, before and after metal interconnect formation as described above. Exposed. Suitable substrates include, but are not limited to, plastics such as silicon, silicon on insulator (SOI), silicon germanium, silicon dioxide, glass, silicon nitride, ceramics, aluminum, copper, gallium arsenide, polycarbonate Circuit boards such as FR-4, hybrid substrates such as polyimide and aluminum nitride-alumina. Such a substrate may further include a thin film thereon. Such thin films include, but are not limited to, metal nitrides (metal nitrides), metal carbides, metal silicides, metal oxides, and mixtures thereof. In multilayer integrated circuit (IC) devices, the underlying layers of insulated and planarized circuit lines can also serve as substrates. However, the choice of substrate or device is limited only by the thermal and chemical stability on the substrate at temperature and pressure.

  Low k dielectric materials, including porogen materials, are processed in a UV irradiator. The UV irradiator is preferably first purged (purged) with nitrogen, helium or argon, and the UV radiation is introduced into the processing chamber using minimal spectral absorbance. The dielectric material is positioned inside the processing chamber. The process chamber is isolated and purged, nitrogen, hydrogen, argon, helium, neon, water vapor, and x is an integer between 1 and 6, y is an integer between 4 and 14, z is 1 to 3 The process is carried out with COz, Oz, CxHy, CxFy and CxHzFy (which are used depending on the application) which are integers up to and a gas exemplified by this mixture. In this regard, UV curing can occur under vacuum conditions, in the absence of oxygen, or with oxidizing gas. The UV light source can be driven by microwaves and is generated by arc discharge, dielectric barrier discharge or electron impact. Furthermore, depending on its application, such as UV-capable bulbs with different spectral distributions, for example microwave electrodeless bulbs identified by type I or II available from Axcelis (Beverly, Massachusetts). Selected. Spectra obtained from Type I and Type II tubes suitable for use with UV cure are shown in FIGS. 1 and 2, respectively.

The wafer temperature is additionally controlled in the range from room temperature to 450 ° C. by an infrared light source, an optical light source, a hot surface or the light source itself. The processing pressure can be less than, greater than or equal to atmospheric pressure. Typically, a UV cured dielectric material is UV treated in less than 300 seconds or about 300 seconds, and more particularly between about 60 seconds and about 180 seconds. Further, the UV treatment may include a temperature between about room temperature and about 450 ° C., a treatment pressure less than, greater than or equal to atmospheric pressure, a UV power between about 0.1 and about 2000 mW / cm ² , about 100 to about It is feasible with a spectrum of UV wavelengths between 400 nm. Further, the UV-cured dielectric material is nitrogen, oxygen, argon, helium, hydrogen, water vapor, x is an integer between 1 and 6, y is an integer between 4 and 14, and z is between 1 and 3. It is possible to perform UV processing by purging with a processing gas such as COz, CxHy, CxFy, CxHzFy, air, and combinations thereof, which are integers of

  The modulus of elasticity and material hardness of a UV-cured dielectric material are improved compared to a furnace material (thermally) cured or not cured at all. Improved low-k materials that are cured by a furnace or not at all are typically about 0.5 gigapascals (GPa) when the dielectric constant is between about 1.6 and about 2.7. ) And about 8 GPa. Typically, the modulus of elasticity of a UV cured dielectric material is greater than or about 2.5 GPa, more typically between about 4 GPa and about 12 GPa. The hardness of the material of the film cured in the furnace or not cured at all is about 0.1 GPa. Typically, the hardness of the UV-cured dielectric material is greater than or about 0.25 GPa, more typically between about 0.25 GPa and about 1.2 GPa. It is in.

  In order that the present disclosure may be more readily understood, reference is made to the following examples. These examples are intended to illustrate the invention, but are not intended to limit the scope of the invention.

Example 1. In this example, a silicon substrate containing a proprietary CVD-deposited SiCOH porogen, including a film, was supplied by the manufacturer. The film was exposed to different UV radiation patterns at 350 ° C. and subjected to FTIR analysis in a RapidCure Exposure tool available from Axcelis Technology. The ultraviolet irradiation pattern was formed using a type I or type II microwave electrodeless tube in an inert atmosphere. Controls that did not include exposure to UV radiation were included in the analysis. As shown in FIG. 3, the absorbance associated with the porogen at about 3000 cm ⁻¹ clearly shows the dependence on wavelength (which is dependent on the wavelength). At wavelengths shorter than 240 nm (type I tube spectrum shown in FIG. 1), exposure to ultraviolet radiation without substantial illumination did not show porogen removal. This absorbance spectrum is similar to the case of the above control. In contrast, exposure to broadband ultraviolet radiation at wavelengths below 240 nm (type II tube shown in FIG. 2) compared to the above control is evidenced by removing the shoulder peaks. As a result, the porogen was substantially removed. Thus, more effective porogen removal was observed at exposure wavelengths from about 180 nm to 240 nm compared to exposure at wavelengths longer than 240 nm.

Example 2. In this example, a silicon substrate containing SiCOH deposited by proprietary CVD, including a film, was provided by the manufacturer. The substrate was processed according to Example 1 using a Type I microwave electrodeless tube. FIG. 4 shows the spectra before and after UV exposure. As evidenced by the absorbance peak at about 950 cm ⁻¹ , exposure to UV radiation showed an increase in Si—O cross-linking (this was by first reducing the Si—OH functionality). The peak associated with the absorbance of Si—CH 3 at about 1300 cm ⁻¹ did not change before and after exposure)), broadening the intensity of absorbance associated with the cross-linking of Si—O. It was. Analysis of the intensity pattern associated with porogen absorbance at 3000 cm ⁻¹ showed that the porogen remains in the low-k dielectric film after exposure to ultraviolet radiation.

  Although the present disclosure has been described with reference to exemplary embodiments, various changes can be made without departing from the scope of the disclosure, and equivalents may be substituted for each component. It will be appreciated by those skilled in the art that this is possible. In addition, many modifications may be made to adapt special cases or materials to the teachings of the disclosure without departing from the essential scope thereof. Therefore, the disclosure is not limited to the specific embodiments disclosed as the best mode contemplated for carrying out the disclosure, but the disclosure is within the scope of the appended claims. It is intended to include all embodiments falling within.

FIG. 1 shows the broadband spectral output of a Type I electrodeless microwave drive tube. FIG. 2 shows the broadband spectral output of a Type II electrodeless microwave drive tube. FIG. 3 is a graph of FTIR spectra of a SIOH low-k dielectric film deposited by CVD with porogen material before and after being exposed to different UV irradiation patterns. FIG. 4 shows the low-k of SIOH deposited by CVD with porogen material before and after exposure to ultraviolet radiation effective to increase the cross-linking density in the low-k dielectric film. It is a graph about the FTIR spectrum of a dielectric material film.

Claims (9)

A process of forming an electrical interconnect structure comprising:
A dielectric material having a low k comprising a matrix and a porogen material, is deposited on the substrate,
Exposing the low-k dielectric material to a first ultraviolet radiation pattern having a wavelength longer than 240 nanometers;
The first UV irradiation pattern increases the cross-linking density of the low-k dielectric material, and the concentration of the porogen material remains the same before and after exposure to the first UV irradiation pattern. To be
And patterning the low-k dielectric material and forming a metal interconnect structure in the patterned low-k dielectric material;
Exposing the low-k dielectric material to a second ultraviolet radiation pattern having a broadband wavelength of less than 240 nanometers to remove the porogen material from the matrix and form a porous low-k dielectric material process which features to Rukoto.   The process of claim 1, wherein the low-k dielectric material has a modulus of elasticity greater than or equal to about 2.5 GPa.   The process of claim 1, wherein the low-k dielectric material has a material hardness of 0.25 GPa or more.   The process of claim 1, wherein the low-k dielectric material has a material hardness between about 0.25 GPa and about 1.2 GPa.   The process of claim 1, wherein the low-k dielectric material has an elastic modulus between about 4 GPa and about 12 GPa.   The process of claim 1, wherein forming the metal interconnect structure comprises depositing copper metal. The process of claim 1, wherein the porogen material degrades upon exposure to the second ultraviolet radiation pattern to form volatile residues or radicals. 2. The exposure of claim 1 wherein exposing the dielectric material to the second ultraviolet radiation pattern includes purging the atmosphere around the dielectric material with an inert gas. process. Exposing the low-k dielectric material to the second UV radiation pattern comprises nitrogen, hydrogen, argon, helium, neon, water vapor, x is an integer from 1 to 6, y is an integer from 4 to 14, z The process according to claim 1 , wherein the process is performed in an atmosphere of COz, Oz, CxHy, CxFy, CxHzFy, and a mixed gas thereof, wherein is an integer of 1 to 3.