WO2001004954A1 - Semiconductor devices and process for manufacture - Google Patents

Semiconductor devices and process for manufacture Download PDF

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Publication number
WO2001004954A1
WO2001004954A1 PCT/US2000/018830 US0018830W WO0104954A1 WO 2001004954 A1 WO2001004954 A1 WO 2001004954A1 US 0018830 W US0018830 W US 0018830W WO 0104954 A1 WO0104954 A1 WO 0104954A1
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Prior art keywords
reaction solution
solvent
crosslinking agent
polymer precursor
polymer
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PCT/US2000/018830
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French (fr)
Inventor
Paul G. Apen
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Nanocell, Inc.
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Priority to AU59268/00A priority Critical patent/AU5926800A/en
Publication of WO2001004954A1 publication Critical patent/WO2001004954A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/52—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
    • H01L23/522—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
    • H01L23/532—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body characterised by the materials
    • H01L23/5329—Insulating materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
    • H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
    • H01L21/02282—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process liquid deposition, e.g. spin-coating, sol-gel techniques, spray coating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
    • H01L21/02118—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer carbon based polymeric organic or inorganic material, e.g. polyimides, poly cyclobutene or PVC
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
    • H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
    • H01L21/02126—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02296—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer
    • H01L21/02318—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer post-treatment
    • H01L21/02345—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer post-treatment treatment by exposure to radiation, e.g. visible light
    • H01L21/02348—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer post-treatment treatment by exposure to radiation, e.g. visible light treatment by exposure to UV light
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001—Technical content checked by a classifier
    • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Definitions

  • the present invention relates to semiconductor devices and, in particular, to semiconductor devices having a dielectric polymer low dielectric material and processes for manufacture thereof.
  • semiconductor device manufacturers have sought to reduce the line width and spacing of interconnects while minimizing the transmission losses and capacitative coupling of the interconnects.
  • One way to diminish power consumption and capacitative coupling is to decrease the dielectric constant of the insulating material, or dielectric, that separates the interconnects.
  • Silicon dioxide which has a dielectric constant (k) of about 4.0, is commonly used as the dielectric in semiconductor devices today. While SiO 2 has the mechanical and thermal stability needed to withstand the thermal cycling and processing steps of semiconductor device manufacturing, materials having a lower dielectric constant are desired.
  • devices having interconnect line widths of 0.07 microns will require the insulating material to have k ⁇ 1.5.
  • Nanoporous silica is SiO 2 having small pockets or pores of air incorporated therein. Air has a dielectric constant of about 1.0, and the dielectric constant of nanoporous silica varies approximately linearly between 4.0 and 1.0 with the amount of air incorporated therein. For example, at 50% porosity, nanoporous silica has k ⁇ 2.5, and at 75% porosity, k ⁇ 1.75.
  • nanoporous silica To achieve k ⁇ 2.0 requires nanoporous silica to be more than 50% porous. At such high porosity, nanoporous silica has several drawbacks. SiO 2 is a very brittle material, and at such high porosity, nanoporous silica lacks mechanical integrity and tends to break and crumble under pressure, such as that applied during various semiconductor device processing steps. Also, nanoporous silica is very hydrophilic and will absorb any water that is present during semiconductor device processing or operation, resulting in reliability problems.
  • the present invention provides a semiconductor device having a low dielectric constant material comprising a dielectric polymer.
  • the dielectric polymer is formed by dispensing a reaction solution made up of a polymer precursor, a crosslinking agent, and a solvent on a substrate and reacting the polymer precursor with the crosslinking agent. The solvent may be removed either before or after the polymer precursor and the crosslinking agent are reacted.
  • This invention also provides an electronic package comprising a low dielectric polymer material, a method for forming a semiconductor device having a low dielectric polymer layer, and a method for forming an electronic package comprising a low dielectric polymer material.
  • Figure 1 depicts a semiconductor device of the present invention
  • Figure 2 is a flowchart illustrating the steps for forming a dielectric layer of a semiconductor device in accordance with one embodiment of the present invention
  • Figure 3 is a flowchart illustrating another embodiment of a method of forming a dielectric layer
  • Figure 4 is a flowchart illustrating still another embodiment of a method of forming a dielectric layer according to the present invention.
  • Figure 5 is a flowchart illustrating the steps for forming an electronic package in accordance with one embodiment of the present invention.
  • the present invention provides a semiconductor device having a dielectric layer comprising a dielectric polymer and a process for the manufacture thereof.
  • semiconductor device includes integrated circuits, microprocessors, integrated circuit chips, and large area integrated circuits.
  • dielectric polymer refers to a crosslinked polymer that acts as an insulator within a semiconductor device and that may have voids or pores incorporated therein.
  • Polymer refers to a molecule comprising a series of repeating molecular subunits.
  • Figure 1 shows a semiconductor device 10 having an interconnect 20 between an upper layer 30 and a substrate 40, with the interconnect 20 being surrounded by a dielectric layer 50.
  • the upper layer 30 and the substrate 40 may each contain numerous sublayers and features, such as trenches, other interconnects, devices, isolation regions, etc.
  • the interconnect 20 may comprise any metal, such as aluminum, copper, or tungsten, and may be formed by any number of techniques known to those of ordinary skill in the art, such as damascene, gap fill, pattern and etch, etc..
  • the dielectric layer 50 comprises a dielectric polymer.
  • the present invention utilizes polymerization reactions in situ to build the dielectric polymer on a substrate.
  • the dielectric polymer is formed by dispensing and reacting a reaction solution on a substrate.
  • the reaction solution comprises a polymer precursor, a crosslinking agent, and a solvent. Reacting the reaction solution results in the polymerization of the polymer precursor with the crosslinking agent to produce a crosslinked dielectric polymer.
  • the solvent may be removed prior to, or after, reacting the reaction solution.
  • polymer precursor refers to a molecular species that serves as a building block to produce higher molecular weight polymers.
  • a “crosslinking agent” refers to a molecular species that serves to chemically link the polymer precursor species to one another. Polymer precursors and crosslinking agents include, without limitation, dimers, trimers, oligomers, and polymers.
  • a general reaction scheme for forming the dielectric polymer in accordance with the present invention is as follows:
  • Polymer Precursor + Crosslinking Agent + Solvent Polymer Solvent
  • the choice of polymer precursor, crosslinking agent and solvent will depend upon the particular reaction mechanism by which the polymer precursor and crosslinking agent are reacted.
  • the reaction proceeds via a condensation mechanism, such as a Friedel-Crafts condensation.
  • the reaction proceeds via a radical polymerization mechanism.
  • polymer precursors reacts to produce higher molecular weight polymers.
  • Polymer precursors may include polymeric and oligomeric molecular species.
  • Examples of polymer precursors that may be used in accordance with the present invention include, without limitation: simple aromatic and polyaromatic hydrocarbons, such as benzene, naphthalene, bibenzyl, biphenyl, m- terphenyl, diphenylmethane; aromatic-group containing polymers such as Kraton, and polystyrene; complex polyaromatic hydrocarbons, such as triphenyl benzene, pyrene, anthracene, triphenylene, tetraphenylmethane, and triptycene; polyphenylene oxides and derivatives; acrylates and methacrylates; acrylate or methacrylate functionalized polyesters; polyarylenethers, polyimides, and similar derivatives; polyetherimides; styrene modified polyesters,
  • Polymer precursors other than those listed above can be used in accordance with the present invention.
  • Polymer precursors may be used alone or in combination with each other.
  • the combinations may include both organic and inorganic polymer precursors.
  • the combination of an inorganic polymer precursor with an organic polymer precursor is believed to increase the thermal stability of the dielectric polymer layer.
  • Inorganic polymer precursors such as organic compounds containing boron, silicon, or aluminum are particularly suited for use in the dielectric polymers of the present invention.
  • the choice of polymer precursor will depend on the type of curing method used. For thermal curing, the preferred polymer precursor will have an aromatic group. For ultraviolet irradiation curing, the preferred polymer precursor will have a vinyl group, specifically, a vinyl group that can participate in a radical reaction.
  • crosslinking agent acts to chemically link polymer precursor species to one another.
  • crosslinking agents include, without limitation: dichloroxylene; dichloromethylbiphenyl; tris(chloromethyl)trimethylbenzene, chloromethylated polystyrene and similar derivatives; terephthaloyl chloride and related derivatives; styrenics, divinylbenzene, and substituted styrenics; and bismaleimides, substituted bismaleimides, and their derivatives; multifunctional acrylates and methacrylates; acrylate or methacrylate functionalized polyesters, polyarylenethers, polyimides, and similar derivatives.
  • Crosslinking agents may be used alone or in combination with each other.
  • the combinations may include both organic and inorganic crosslinking agents.
  • the choice of crosslinking agent will depend on the type of curing method used.
  • the preferred crosslinking agents For thermal curing, the preferred crosslinking agents have at least two leaving groups attached to benzylic carbons.
  • the preferred crosslinking agents For ultraviolet irradiation curing, the preferred crosslinking agents have two or more vinyl groups, specifically, vinyl groups that can participate in a radical reaction.
  • the polymer precursors are oligomers and polymers having medium to high molecular weights in excess of 5,000 g/mol, more typically in a range of about 50,000 g/mol to about 150,000 g/mol, and the crosslinking agents are dimers and trimers with low molecular weights below 1500 g/mol, more typically in a range of about 150 g/mol to about 1000 g/mol.
  • Use of a polymer precursor and a crosslinking agent having these relative molecular weights is beneficial in that the resulting dielectric layer has better uniformity and thermal stability.
  • both the polymer precursor and the crosslinking agent are medium to high molecular weights. This can lead to improved film uniformity and improved thermal stability and mechanical properties.
  • the polymer precursor and crosslinking agent can be distinct species or chemically bonded to each other prior to deposition and crosslinking.
  • the polymer precursors and crosslinking agent are chosen to have a high aromatic content with at least one aromatic group per molecular repeat unit and low or no aliphatic content.
  • Aromatic molecular species are known to possess good chemical and thermal stability properties, and dielectric polymers comprising a high aromatic content would be expected to similarly exhibit good chemical and thermal stability properties.
  • the relative amounts of polymer precursor and crosslinking agent will depend upon the choice of polymer precursor, crosslinking agent, solvent and curing method.
  • the reaction solution includes about 1% to about 20% by weight of the crosslinking agent, with a range of about 2% to about 15% by weight of the crosslinking agent being more typical. Below about 2% the resulting dielectric layer has poor thermal and mechanical stability, and above about 15% the resulting dielectric layer has poor uniformity and is susceptible to cracking.
  • the solvent is chosen to dissolve the monomer and the crosslinking agent as well as to be chemically unreactive with the substrate and with the polymer precursor and crosslinking agent during polymerization.
  • the solvent has a medium to high boiling point (i.e., a low to medium vapor pressure) such as in a range of about 80°C to about 250°C.
  • the solvent typically has a boiling point of at least about 150°C. Solvents with a boiling point of less than about 150°C tend to evaporate during processing, causing the crosslinking agent to precipitate out of the reaction solution and therefore causing non-uniformity in the resulting dielectric layer.
  • solvents examples include, without limitation: dichloroethane and other halogenated hydrocarbons; alcohols; glycols and glycol ethers; esters; and aromatic and aliphatic hydrocarbons. These solvents may be used alone or in combination with each other or other solvents. One embodiment uses a combination of high and low boiling point solvents. Solvents other than those listed above may be used in accordance with the present invention.
  • a "catalyst” refers to a chemical species that may be added to the reaction solution to initiate, accelerate, and/or control the reaction of the polymer precursor with the crosslinking agent.
  • the present invention does not always require the addition of a catalyst.
  • the choice of catalyst, if used, will depend upon the particular reaction mechanism by which the reaction of the polymer precursor with the crosslinking agent proceeds.
  • the catalyst may be in the form of a Lewis acid, a photoinitiator, or a photosensitizer.
  • suitable catalysts include a strong Lewis acid, such as tin tetrachloride, aluminum trichloride, and boron trifluoride. Other catalysts may also be used. Such catalysts may be used alone or in combination with one another.
  • a catalyst in the form of a photoinitiator and/or photosensitizer may be used.
  • photoinitiators which are useful in the present invention include, without limitation: alkyl and aryl peroxides; benzophenone, benzil, and quinone derivatives; benzoin derivatives such as benzoin alkyl ethers; dimethoxyphenylacetophenone, diethoxyphenylacetophenone, and related derivatives; azo compounds such as azobisisobutyronitrile; metal chelates; and inorganic donor-acceptor complexes.
  • photosensitizers examples include, without limitation: cyanonaphthalene, xanthene dyes, methylene blue, thioxanthene, and related derivatives.
  • Photoinitiators can be used alone or in combination with other photoinitiators and with a photosensitizer.
  • Photosensitizers can be used alone, in conjunction with a photoinitiator, with electron donating species such as amines, or in combination with other photosensitizers.
  • photoinitiators and photosensitizers other than those listed here may be used in accordance with the present invention.
  • Figure 2 outlines one embodiment of a process for forming a semiconductor device having a dielectric polymer layer.
  • a substrate is provided.
  • the substrate may be a pure semiconductor substrate or wafer (doped or undoped), a semiconductor substrate with epitaxial layers, a semiconductor substrate incorporating one or more device layers at any stage of processing, or any other type of substrate incorporating one or more semiconductor layers.
  • a reaction solution formed by mixing together a polymer precursor, a crosslinking agent, and a solvent is dispensed upon a substrate in a next step 210.
  • a catalyst is added to the reaction solution.
  • the reaction solution may be dispensed on the substrate by any number of techniques.
  • dispensing the reaction solution involves spin-coating the reaction solution onto the substrate using standard spin-coating equipment available in the semiconductor device manufacturing industry. Typically, the reaction solution is spin-coated at ambient conditions.
  • the coating thickness can be controlled by altering the viscosity of the reaction solution through, for example, altering the percentage of solids to liquids, the type of solvent used, or the chemical composition of the reaction solution. Coating thickness also can be controlled by controlling the spin rate and/or the dispense rate, or through other techniques known to those of ordinary skill in the art.
  • a next step 220 the polymer precursor and the crosslinking agent are reacted in situ on the substrate to form a dielectric polymer. Reacting the polymer precursor and the crosslinking agent together chemically bonds the polymer precursor with the crosslinking agent to form a crosslinked dielectric polymer.
  • the reaction of the polymer precursor with the crosslinking agent proceeds via a Friedel-Crafts condensation mechanism, and reacting the polymer precursor with the crosslinking agent may include heating the reaction solution to a temperature in a range of about 60°C to the.boiling point of the solvent.
  • the reaction of the polymer precursor with the crosslinking agent proceeds via a radical polymerization mechanism, and reacting the polymer precursor with the crosslinking agent may involve irradiating the reaction solution with ultraviolet radiation.
  • the reaction solution is irradiated with ultraviolet radiation having a wavelength between about 190 nm and about 300 nm, although other wavelengths in the ultraviolet range can be used.
  • the final step 230 involves removing the solvent from the crosslinked polymer.
  • Removing the solvent may be accomplished by any number of techniques, such as: air drying; vacuum drying; heating, e.g., on a hot plate or in an oven; solvent exchange; and supercritical drying. Removing the solvent may also involve a combination of more than one such technique.
  • the solvent is removed after the polymer precursor and the crosslinking agent have been reacted.
  • the solvent may be removed, wholly or partially, either before or after reacting the polymer precursor with the crosslinking agent.
  • Figures 3 and 4 show other embodiments of a process of forming a dielectric polymer layer in situ on a substrate.
  • the embodiments illustrated in Figures 3 and 4 each involve the reaction of the polymer precursor with a crosslinking agent that proceeds via a Friedel-Crafts condensation.
  • step 300 involves dispensing a reaction solution comprising a polymer precursor, a crosslinking agent, and a first solvent on a substrate.
  • a catalyst such as a Lewis acid, may be added to the reaction solution before dispensing it on the substrate.
  • the first solvent is evaporated from the reaction solution before or as the reaction solution is aged to form a polymer film at step 320.
  • Aging the reaction solution involves heating at a first temperature in a range of about 80°C to about 200°C for about 30 minutes to about 6 hours. Aging helps initiate and/or complete the reaction of the polymer precursor with the crosslinking agent that forms the dielectric polymer layer.
  • the polymer film is rinsed with a second solvent at step 330.
  • the second solvent may be the same as or different from the first solvent. Examples of second solvents that may be used in accordance with the present invention include, without limitation: cyclohexanone, acetone, isopropanol and methanol.
  • the second solvent rinse removes unreacted polymer precursor and crosslinking agent, but does not dissolve the dielectric polymer film. Two or more solvent rinses may be performed.
  • the polymer film is cured at step 340 to form a dielectric polymer layer.
  • Curing helps complete the reaction of the polymer precursor with the crosslinking agent, removes any volatiles, further stabilizes the film and can reduce the dielectric constant.
  • Curing typically involves heating the polymer film to a second temperature above about 200°C for about 5 minutes to about 60 minutes. In one embodiment, the polymer film is cured at a second temperature above about 300°C for 30 minutes.
  • Figure 4 illustrates still another embodiment of a process according to the present invention.
  • This embodiment begins with dispensing a reaction solution on a substrate at step 400 as described previously.
  • the reaction solution is aged in an environment saturated with the solvent.
  • the solvent saturated environment helps prevent the solvent from evaporating from the reaction solution during aging.
  • aging typically involves heating the reaction solution to a first temperature in a range of about 60°C to about 200°C for 1 to 6 hours in order to initiate and/or complete the reaction of the polymer precursor with the crosslinking agent that produces a dielectric polymer film.
  • the solvent is then removed from the polymer film at step 420.
  • the polymer film is rinsed at step 430, and the polymer film is cured at step 440, as described previously.
  • FIG. 5 outlines a process for forming electronic packages in accordance with the present invention.
  • a reaction solution formed by mixing together a polymer precursor, a crosslinking agent, and a solvent is dispensed onto a fibrous mat.
  • the fibrous mat may be woven or non- woven, and may comprise glass fibers, halocarbon fibers, or fluorocarbon fibers. Other types of fibrous mats useful for electronic packages may also be used in accordance with the present invention.
  • the polymer precursor and the crosslinking agent are reacted to form a dielectric polymer around the fibers of the fibrous mat.
  • the fibrous mat is first placed in a press, and the reaction solution polymerized in the press. Last 520, the remaining solvent is removed to yield an electronic package.
  • Circuitization and devices are applied to the electronic packages of the present invention in the same manner as in electronic packages of the prior art.
  • the steps described in figures 3 and 4 may also be used to manufacture electronic packages.
  • reaction solution by mixing and dissolving polystyrene (0.149 g, 1.43 mmoles, MW 125,000) and p-dichloroxylene (0.250 g, 1.43 mmoles) in 1 ,4-dichlorobutane (2.0 mL) until solution was homogenous. Added tin tetrachloride (0.2-0.4mL, 0.3 mmoles, IM in dichloromethane) to solution and mixed. Dispensed solution onto wafer substrate, and spin-coated at 1500 rpm for 10 seconds producing a liquid film. Solvent was evaporated at 150°C for 1 minute to produce uniform, stable film. Film was then aged at
  • the film was spin-dried at 1500 rpm for one minute and the oven-dried at 150°C for 2
  • Dielectric film was cured at 300° or higher for thirty minutes.
  • Dielectric film was cured at 300° or higher for thirty minutes.
  • reaction solution by mixing and dissolving polystyrene (0.149g, 1.43 mmoles, MW 125,000) and p-dichloroxylene (0.250g, 1.43 mmoles) in 1 ,4-dichlorobutane (2.0 mL) until solution was homogenous.
  • Added tin tetrachloride solution (0.2-0.4mL, 0.3 mmoles, IM in dichloromethane) to solution and mixed.
  • the film was spin-dried at 1500 rpm for one minute. Oven-dried film at 150°C for 2 hours to produce an approximately 5000A thin film
  • poly(4-vinylbenzylchloride) by polymerizing 4-vinylbenzylchloride with a polymerization initiator such as azo(bisisobutyronitrile) in 1 ,2-dichloroethane or 1 ,4- dichlorobutane.
  • a polymerization initiator such as azo(bisisobutyronitrile) in 1 ,2-dichloroethane or 1 ,4- dichlorobutane.
  • the solution was heated to 70°C for sixteen hours and polymer
  • poly(4-vinylbenzylchloride) by polymerizing 4-vinylbenzylchloride with a polymerization initiator such as azo(bisisobutyronitrile) in 1,2-dichloroethane or 1,4- dichlorobutane.
  • a polymerization initiator such as azo(bisisobutyronitrile) in 1,2-dichloroethane or 1,4- dichlorobutane.
  • the solution was heated to 70°C for sixteen hours and polymer
  • poly(styrene-co-4-vinylbenzylchloride) co-polymer by mixing 4- vinylbenzylchloride (1-100 mole %) with styrene (0-99 mole %) in 1,2-dichloroethane or 1,4-dichlorobutane.
  • a polymerization initiator such as azo(bisisobutyronitrile) was added to the solution. The solution was heated to 70°C for sixteen hours and polymer
  • tetrachloride (0.1-0.5 mL, 0.3 mmoles, IM solution in dichloromethane) was added. The solution was dispensed onto a wafer substrate and spin-coated at 1500 rpm for 10 seconds to produce a liquid film.
  • the film was spin-dried at 1500 rpm for one minute. Oven-dried film at 150°C for 2 hours to produce an approximately 3500A thin film dielectric.
  • reaction solution by mixing and dissolving poly(2,6-dimethyl-l,4- phenyleneoxide) (0.163 g, 1.36 mmoles) and p-dichloroxylene (0.237 g, 1.36 mmoles) in 1,4-dichlorobutane (2.0 mL) until solution was homogenous. Added tin tetrachloride (0.2- 0.4mL, 0.3 mmoles, IM in dichloromethane) to solution and mixed. Dispensed solution onto wafer substrate, and spin-coated at 1500 rpm for 10 seconds producing a liquid film. Solvent was evaporated at 150°C for 1 minute to produce uniform, stable film. Film was
  • the film was spin-dried at 1500 rpm for one minute.
  • the film was spin-dried at 1500 rpm for one minute. Oven-dried film at 150°C for 2
  • Dielectric film was cured at 300° or higher
  • the dielectric polymer layers of the present invention are generally compatible with semiconductor device fabrication process steps, such as film deposition and curing, etching, electroplating, and chemical-mechanical polishing.
  • Mechanical properties of these dielectric polymers such as modulus, compressive strength, adhesion and cohesion, can be tailored by the choice of reactants and reaction conditions, such as the type of solvent, reaction temperature, and reaction time.
  • dielectric polymers of the present invention demonstrate thermal stability in excess of 300°C and good isothermal stability at elevated temperatures, and can exhibit T g greater than 400°C.
  • the elastic modulus of these dielectric polymers is typically in excess of 5 GPa.
  • the hardness of a film is typically around 0.3 Gpa, as measured by nanoindentation.
  • the dielectric constant of these polymers is typically 2.5 or below.

Abstract

Semiconductor device having a low dielectric constant material comprising a dielectric polymer and methods for forming such are described. The semiconductor device is formed by depositing a layer of a reaction solution, curing the reaction solution to form a dielectric polymer, and then processing the dielectric polymer to leave the dielectric polymer layer on the substrate. The reaction solution is formed by mixing together a polymer precursor, a crosslinking agent, and a solvent. The dielectric polymers of the present invention have a dielectric constant that can be tailored from about 3.0 to 1.0 and have mechanical properties that can be tailored by choice of reactants and reaction conditions.

Description

SEMICONDUCTOR DEVICES AND PROCESS FOR MANUFACTURE
This application claims the benefit of U.S. Provisional Application No. 60/142,873, filed July 8, 1999, and U.S. Provisional Application No. 60/152,295, filed September 3, 1999.
FIELD OF THE INVENTION
The present invention relates to semiconductor devices and, in particular, to semiconductor devices having a dielectric polymer low dielectric material and processes for manufacture thereof.
BACKGROUND
In an effort to increase the performance and speed of semiconductor devices, semiconductor device manufacturers have sought to reduce the line width and spacing of interconnects while minimizing the transmission losses and capacitative coupling of the interconnects. One way to diminish power consumption and capacitative coupling is to decrease the dielectric constant of the insulating material, or dielectric, that separates the interconnects.
Silicon dioxide (SiO2), which has a dielectric constant (k) of about 4.0, is commonly used as the dielectric in semiconductor devices today. While SiO2 has the mechanical and thermal stability needed to withstand the thermal cycling and processing steps of semiconductor device manufacturing, materials having a lower dielectric constant are desired.
There have been several efforts to develop lower dielectric constant materials. Table 1 summarizes the development of several materials having dielectric constants in the 3.5 to 2.0 range. able 1. Recent Low Dielectric Developments.
Figure imgf000004_0001
However, as interconnect line widths decrease, concomitant decreases in the dielectric constant of the insulating material will be required to achieve the improved performance and speed desired of future semiconductor devices, as Table 2 illustrates.
For example, devices having interconnect line widths of 0.07 microns will require the insulating material to have k < 1.5.
Table 2. Summary of Selected Interconnect Road Map Objectives
Figure imgf000004_0002
Maximum Interconnect Length
820 1,480 12,160 2,840 5,140 10,000 (Meters/Chip) pontact/Via Aspect Ratio" 12.2:1 12.2:1 .4:1 12.5:1 2.7:1 12.9:1
IMetal Height/Width Ratio* 1.8:1 1.8:1 .0:1 12.1:1 β.4:l 12.7:1 ϊffective IMDf Dielectric
3.0-4.1 Ϊ2.5-3.0 12.0-2.5 1.5-2.0 1.5-2.0 Constant Hi .5
* Metal and via aspect ratios are additive for dual damascene process flows. f IMD = Intermetal Dielectric
Source: SLA National Technology Roadmapfor Semiconductors
The only material currently being developed having k < 2.0 is nanoporous silica. Nanoporous silica is SiO2 having small pockets or pores of air incorporated therein. Air has a dielectric constant of about 1.0, and the dielectric constant of nanoporous silica varies approximately linearly between 4.0 and 1.0 with the amount of air incorporated therein. For example, at 50% porosity, nanoporous silica has k ~ 2.5, and at 75% porosity, k ~ 1.75.
To achieve k < 2.0 requires nanoporous silica to be more than 50% porous. At such high porosity, nanoporous silica has several drawbacks. SiO2 is a very brittle material, and at such high porosity, nanoporous silica lacks mechanical integrity and tends to break and crumble under pressure, such as that applied during various semiconductor device processing steps. Also, nanoporous silica is very hydrophilic and will absorb any water that is present during semiconductor device processing or operation, resulting in reliability problems.
Thus, a need exists for an improved low dielectric constant material for use in semiconductor devices.
SUMMARY OF THE INVENTION
The present invention provides a semiconductor device having a low dielectric constant material comprising a dielectric polymer. The dielectric polymer is formed by dispensing a reaction solution made up of a polymer precursor, a crosslinking agent, and a solvent on a substrate and reacting the polymer precursor with the crosslinking agent. The solvent may be removed either before or after the polymer precursor and the crosslinking agent are reacted. This invention also provides an electronic package comprising a low dielectric polymer material, a method for forming a semiconductor device having a low dielectric polymer layer, and a method for forming an electronic package comprising a low dielectric polymer material.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:
Figure 1 depicts a semiconductor device of the present invention;
Figure 2 is a flowchart illustrating the steps for forming a dielectric layer of a semiconductor device in accordance with one embodiment of the present invention;
Figure 3 is a flowchart illustrating another embodiment of a method of forming a dielectric layer;
Figure 4 is a flowchart illustrating still another embodiment of a method of forming a dielectric layer according to the present invention; and
Figure 5 is a flowchart illustrating the steps for forming an electronic package in accordance with one embodiment of the present invention.
DETAILED DESCRIPTION
The present invention will be described below in connection with the Figures and with certain embodiments. In the following description, specific details are set forth to provide a thorough understanding of the present invention, however, it will be appreciated by those of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known components, structures and techniques have been omitted to avoid obscuring the present invention.
The present invention provides a semiconductor device having a dielectric layer comprising a dielectric polymer and a process for the manufacture thereof. It will be appreciated that, as used herein, "semiconductor device" includes integrated circuits, microprocessors, integrated circuit chips, and large area integrated circuits. A "dielectric polymer" as used herein refers to a crosslinked polymer that acts as an insulator within a semiconductor device and that may have voids or pores incorporated therein. "Polymer" refers to a molecule comprising a series of repeating molecular subunits.
Figure 1 shows a semiconductor device 10 having an interconnect 20 between an upper layer 30 and a substrate 40, with the interconnect 20 being surrounded by a dielectric layer 50. It is to be understood that the upper layer 30 and the substrate 40 may each contain numerous sublayers and features, such as trenches, other interconnects, devices, isolation regions, etc.. The interconnect 20 may comprise any metal, such as aluminum, copper, or tungsten, and may be formed by any number of techniques known to those of ordinary skill in the art, such as damascene, gap fill, pattern and etch, etc..
In accordance with the present invention, the dielectric layer 50 comprises a dielectric polymer. The present invention utilizes polymerization reactions in situ to build the dielectric polymer on a substrate. The dielectric polymer is formed by dispensing and reacting a reaction solution on a substrate. The reaction solution comprises a polymer precursor, a crosslinking agent, and a solvent. Reacting the reaction solution results in the polymerization of the polymer precursor with the crosslinking agent to produce a crosslinked dielectric polymer. The solvent may be removed prior to, or after, reacting the reaction solution.
As used herein, "polymer precursor" refers to a molecular species that serves as a building block to produce higher molecular weight polymers. A "crosslinking agent" refers to a molecular species that serves to chemically link the polymer precursor species to one another. Polymer precursors and crosslinking agents include, without limitation, dimers, trimers, oligomers, and polymers. A general reaction scheme for forming the dielectric polymer in accordance with the present invention is as follows:
Polymer Precursor + Crosslinking Agent + Solvent Polymer
Figure imgf000007_0001
Solvent The choice of polymer precursor, crosslinking agent and solvent will depend upon the particular reaction mechanism by which the polymer precursor and crosslinking agent are reacted. In one embodiment, the reaction proceeds via a condensation mechanism, such as a Friedel-Crafts condensation. In another embodiment, the reaction proceeds via a radical polymerization mechanism.
The polymer precursor, in accordance with the present invention, reacts to produce higher molecular weight polymers. Polymer precursors may include polymeric and oligomeric molecular species. Examples of polymer precursors that may be used in accordance with the present invention include, without limitation: simple aromatic and polyaromatic hydrocarbons, such as benzene, naphthalene, bibenzyl, biphenyl, m- terphenyl, diphenylmethane; aromatic-group containing polymers such as Kraton, and polystyrene; complex polyaromatic hydrocarbons, such as triphenyl benzene, pyrene, anthracene, triphenylene, tetraphenylmethane, and triptycene; polyphenylene oxides and derivatives; acrylates and methacrylates; acrylate or methacrylate functionalized polyesters; polyarylenethers, polyimides, and similar derivatives; polyetherimides; styrene modified polyesters, and similar derivatives; maleimides, substituted maleimides, and their derivatives; and substituted polyamic esters and their derivatives; polyquinoxalines and similar derivatives; polyquinolines; diphenyldimethylsilane; triphenylsilane; diphenylborane; polyphenylsiloxanes and similar derivatives; alkyl or aryl vinyl silanes; modified vinyl silanes; and vinyl silane oligomers and polymers. Polymer precursors other than those listed above can be used in accordance with the present invention. Polymer precursors may be used alone or in combination with each other. The combinations may include both organic and inorganic polymer precursors. The combination of an inorganic polymer precursor with an organic polymer precursor is believed to increase the thermal stability of the dielectric polymer layer. Inorganic polymer precursors such as organic compounds containing boron, silicon, or aluminum are particularly suited for use in the dielectric polymers of the present invention. The choice of polymer precursor will depend on the type of curing method used. For thermal curing, the preferred polymer precursor will have an aromatic group. For ultraviolet irradiation curing, the preferred polymer precursor will have a vinyl group, specifically, a vinyl group that can participate in a radical reaction.
The crosslinking agent, in accordance with the present invention, acts to chemically link polymer precursor species to one another. Examples of crosslinking agents include, without limitation: dichloroxylene; dichloromethylbiphenyl; tris(chloromethyl)trimethylbenzene, chloromethylated polystyrene and similar derivatives; terephthaloyl chloride and related derivatives; styrenics, divinylbenzene, and substituted styrenics; and bismaleimides, substituted bismaleimides, and their derivatives; multifunctional acrylates and methacrylates; acrylate or methacrylate functionalized polyesters, polyarylenethers, polyimides, and similar derivatives. Crosslinking agents may be used alone or in combination with each other. The combinations may include both organic and inorganic crosslinking agents. The choice of crosslinking agent will depend on the type of curing method used. For thermal curing, the preferred crosslinking agents have at least two leaving groups attached to benzylic carbons. For ultraviolet irradiation curing, the preferred crosslinking agents have two or more vinyl groups, specifically, vinyl groups that can participate in a radical reaction.
In one embodiment, the polymer precursors are oligomers and polymers having medium to high molecular weights in excess of 5,000 g/mol, more typically in a range of about 50,000 g/mol to about 150,000 g/mol, and the crosslinking agents are dimers and trimers with low molecular weights below 1500 g/mol, more typically in a range of about 150 g/mol to about 1000 g/mol. Use of a polymer precursor and a crosslinking agent having these relative molecular weights is beneficial in that the resulting dielectric layer has better uniformity and thermal stability. It is possible to get the same benefits from interchanging the relative molecular weights of the polymer precursor to the crosslinking agent, i.e., the polymer precursor having low molecular weights and the crosslinking agent having medium to high molecular weights. In one embodiment, both the polymer precursor and the crosslinking agent are medium to high molecular weights. This can lead to improved film uniformity and improved thermal stability and mechanical properties. In this embodiment, the polymer precursor and crosslinking agent can be distinct species or chemically bonded to each other prior to deposition and crosslinking.
In one embodiment, the polymer precursors and crosslinking agent are chosen to have a high aromatic content with at least one aromatic group per molecular repeat unit and low or no aliphatic content. Aromatic molecular species are known to possess good chemical and thermal stability properties, and dielectric polymers comprising a high aromatic content would be expected to similarly exhibit good chemical and thermal stability properties.
The relative amounts of polymer precursor and crosslinking agent will depend upon the choice of polymer precursor, crosslinking agent, solvent and curing method. In one embodiment, the reaction solution includes about 1% to about 20% by weight of the crosslinking agent, with a range of about 2% to about 15% by weight of the crosslinking agent being more typical. Below about 2% the resulting dielectric layer has poor thermal and mechanical stability, and above about 15% the resulting dielectric layer has poor uniformity and is susceptible to cracking.
The solvent is chosen to dissolve the monomer and the crosslinking agent as well as to be chemically unreactive with the substrate and with the polymer precursor and crosslinking agent during polymerization. In one embodiment, the solvent has a medium to high boiling point (i.e., a low to medium vapor pressure) such as in a range of about 80°C to about 250°C. The solvent typically has a boiling point of at least about 150°C. Solvents with a boiling point of less than about 150°C tend to evaporate during processing, causing the crosslinking agent to precipitate out of the reaction solution and therefore causing non-uniformity in the resulting dielectric layer. Examples of solvents that may be used in accordance with the present invention include, without limitation: dichloroethane and other halogenated hydrocarbons; alcohols; glycols and glycol ethers; esters; and aromatic and aliphatic hydrocarbons. These solvents may be used alone or in combination with each other or other solvents. One embodiment uses a combination of high and low boiling point solvents. Solvents other than those listed above may be used in accordance with the present invention.
A "catalyst" refers to a chemical species that may be added to the reaction solution to initiate, accelerate, and/or control the reaction of the polymer precursor with the crosslinking agent. The present invention does not always require the addition of a catalyst. The choice of catalyst, if used, will depend upon the particular reaction mechanism by which the reaction of the polymer precursor with the crosslinking agent proceeds. The catalyst may be in the form of a Lewis acid, a photoinitiator, or a photosensitizer.
In one embodiment where the reaction of the polymer precursor with the crosslinking. agent proceeds via a Friedel-Crafts condensation, suitable catalysts include a strong Lewis acid, such as tin tetrachloride, aluminum trichloride, and boron trifluoride. Other catalysts may also be used. Such catalysts may be used alone or in combination with one another.
In another embodiment where the reaction of the polymer precursor with the crosslinking agent proceeds via a radical polymerization mechanism, a catalyst in the form of a photoinitiator and/or photosensitizer may be used. Examples of photoinitiators which are useful in the present invention include, without limitation: alkyl and aryl peroxides; benzophenone, benzil, and quinone derivatives; benzoin derivatives such as benzoin alkyl ethers; dimethoxyphenylacetophenone, diethoxyphenylacetophenone, and related derivatives; azo compounds such as azobisisobutyronitrile; metal chelates; and inorganic donor-acceptor complexes. Examples of photosensitizers that can be used include, without limitation: cyanonaphthalene, xanthene dyes, methylene blue, thioxanthene, and related derivatives. Photoinitiators can be used alone or in combination with other photoinitiators and with a photosensitizer. Photosensitizers can be used alone, in conjunction with a photoinitiator, with electron donating species such as amines, or in combination with other photosensitizers. Those of ordinary skill in the art will appreciate that photoinitiators and photosensitizers other than those listed here may be used in accordance with the present invention.
Figure 2 outlines one embodiment of a process for forming a semiconductor device having a dielectric polymer layer. In a first step 200, a substrate is provided. The substrate may be a pure semiconductor substrate or wafer (doped or undoped), a semiconductor substrate with epitaxial layers, a semiconductor substrate incorporating one or more device layers at any stage of processing, or any other type of substrate incorporating one or more semiconductor layers.
A reaction solution formed by mixing together a polymer precursor, a crosslinking agent, and a solvent is dispensed upon a substrate in a next step 210. In one embodiment, a catalyst is added to the reaction solution. The reaction solution may be dispensed on the substrate by any number of techniques. In one embodiment, dispensing the reaction solution involves spin-coating the reaction solution onto the substrate using standard spin-coating equipment available in the semiconductor device manufacturing industry. Typically, the reaction solution is spin-coated at ambient conditions. The coating thickness can be controlled by altering the viscosity of the reaction solution through, for example, altering the percentage of solids to liquids, the type of solvent used, or the chemical composition of the reaction solution. Coating thickness also can be controlled by controlling the spin rate and/or the dispense rate, or through other techniques known to those of ordinary skill in the art.
In a next step 220, the polymer precursor and the crosslinking agent are reacted in situ on the substrate to form a dielectric polymer. Reacting the polymer precursor and the crosslinking agent together chemically bonds the polymer precursor with the crosslinking agent to form a crosslinked dielectric polymer.
In one embodiment, the reaction of the polymer precursor with the crosslinking agent proceeds via a Friedel-Crafts condensation mechanism, and reacting the polymer precursor with the crosslinking agent may include heating the reaction solution to a temperature in a range of about 60°C to the.boiling point of the solvent. In another embodiment, the reaction of the polymer precursor with the crosslinking agent proceeds via a radical polymerization mechanism, and reacting the polymer precursor with the crosslinking agent may involve irradiating the reaction solution with ultraviolet radiation. Typically, the reaction solution is irradiated with ultraviolet radiation having a wavelength between about 190 nm and about 300 nm, although other wavelengths in the ultraviolet range can be used.
The final step 230 involves removing the solvent from the crosslinked polymer. Removing the solvent may be accomplished by any number of techniques, such as: air drying; vacuum drying; heating, e.g., on a hot plate or in an oven; solvent exchange; and supercritical drying. Removing the solvent may also involve a combination of more than one such technique.
As shown in Figure 2, the solvent is removed after the polymer precursor and the crosslinking agent have been reacted. However, the solvent may be removed, wholly or partially, either before or after reacting the polymer precursor with the crosslinking agent.
Figures 3 and 4 show other embodiments of a process of forming a dielectric polymer layer in situ on a substrate. The embodiments illustrated in Figures 3 and 4 each involve the reaction of the polymer precursor with a crosslinking agent that proceeds via a Friedel-Crafts condensation. Referring to Figure 3, step 300 involves dispensing a reaction solution comprising a polymer precursor, a crosslinking agent, and a first solvent on a substrate. A catalyst, such as a Lewis acid, may be added to the reaction solution before dispensing it on the substrate.
At step 310, the first solvent is evaporated from the reaction solution before or as the reaction solution is aged to form a polymer film at step 320. Aging the reaction solution involves heating at a first temperature in a range of about 80°C to about 200°C for about 30 minutes to about 6 hours. Aging helps initiate and/or complete the reaction of the polymer precursor with the crosslinking agent that forms the dielectric polymer layer. After the reaction solution has been aged to form a polymer film, the polymer film is rinsed with a second solvent at step 330. The second solvent may be the same as or different from the first solvent. Examples of second solvents that may be used in accordance with the present invention include, without limitation: cyclohexanone, acetone, isopropanol and methanol. The second solvent rinse removes unreacted polymer precursor and crosslinking agent, but does not dissolve the dielectric polymer film. Two or more solvent rinses may be performed.
The polymer film is cured at step 340 to form a dielectric polymer layer. Curing helps complete the reaction of the polymer precursor with the crosslinking agent, removes any volatiles, further stabilizes the film and can reduce the dielectric constant. Curing typically involves heating the polymer film to a second temperature above about 200°C for about 5 minutes to about 60 minutes. In one embodiment, the polymer film is cured at a second temperature above about 300°C for 30 minutes.
Figure 4 illustrates still another embodiment of a process according to the present invention. This embodiment begins with dispensing a reaction solution on a substrate at step 400 as described previously. At step 410, the reaction solution is aged in an environment saturated with the solvent. The solvent saturated environment helps prevent the solvent from evaporating from the reaction solution during aging. As described previously, aging typically involves heating the reaction solution to a first temperature in a range of about 60°C to about 200°C for 1 to 6 hours in order to initiate and/or complete the reaction of the polymer precursor with the crosslinking agent that produces a dielectric polymer film. The solvent is then removed from the polymer film at step 420. The polymer film is rinsed at step 430, and the polymer film is cured at step 440, as described previously.
The processes described above can be applied to form electronic packages. Figure 5 outlines a process for forming electronic packages in accordance with the present invention. In a first step 500, a reaction solution formed by mixing together a polymer precursor, a crosslinking agent, and a solvent is dispensed onto a fibrous mat. The fibrous mat may be woven or non- woven, and may comprise glass fibers, halocarbon fibers, or fluorocarbon fibers. Other types of fibrous mats useful for electronic packages may also be used in accordance with the present invention. Next 510, the polymer precursor and the crosslinking agent are reacted to form a dielectric polymer around the fibers of the fibrous mat. In one embodiment, the fibrous mat is first placed in a press, and the reaction solution polymerized in the press. Last 520, the remaining solvent is removed to yield an electronic package. Circuitization and devices are applied to the electronic packages of the present invention in the same manner as in electronic packages of the prior art. In alternative embodiments of the present invention, the steps described in figures 3 and 4 may also be used to manufacture electronic packages.
EXAMPLES Example I
Prepared reaction solution by mixing and dissolving polystyrene (0.149 g, 1.43 mmoles, MW 125,000) and p-dichloroxylene (0.250 g, 1.43 mmoles) in 1 ,4-dichlorobutane (2.0 mL) until solution was homogenous. Added tin tetrachloride (0.2-0.4mL, 0.3 mmoles, IM in dichloromethane) to solution and mixed. Dispensed solution onto wafer substrate, and spin-coated at 1500 rpm for 10 seconds producing a liquid film. Solvent was evaporated at 150°C for 1 minute to produce uniform, stable film. Film was then aged at
150°C for three hours. Film was washed and rinsed with cyclohexanone and/or acetone.
The film was spin-dried at 1500 rpm for one minute and the oven-dried at 150°C for 2
hours to produce an approximately 5000A thin film dielectric. Dielectric film was cured at 300° or higher for thirty minutes.
Example II
Prepared reaction solution by mixing and dissolving polystyrene (0.095 g, 0.914 mmoles, MW 125,000) and p-dichloroxylene (0.320 g, 1.83 mmoles) in 1 ,4-dichlorobutane (2.0 mL) until solution was homogenous. Added tin tetrachloride (0.2-0.4mL, 0.3 mmoles,
IM in dichloromethane) to polymer solution and mixed. Dispensed solution onto wafer substrate, and spin-coated at 1500 rpm for 10 seconds producing a liquid film. Solvent was evaporated at 150°C for 1 minute to produce uniform, stable film. Film was then
aged at 150°C for three hours. Film was washed and rinsed with cyclohexanone and/or
acetone. The film was spin-dried at 1500 rpm for one minute. Oven-dried film at 150°C
for 2 hours to produce an approximately 5000 A thin film dielectric. Dielectric film was cured at 300° or higher for thirty minutes.
Example III
Prepared reaction solution by mixing and dissolving polystyrene (0.149g, 1.43 mmoles, MW 125,000) and p-dichloroxylene (0.250g, 1.43 mmoles) in 1 ,4-dichlorobutane (2.0 mL) until solution was homogenous. Added tin tetrachloride solution (0.2-0.4mL, 0.3 mmoles, IM in dichloromethane) to solution and mixed. Dispensed solution onto wafer substrate, and spin-coated at 1500 rpm for 10 seconds producing a liquid film. Solvent was evaporated at 150°C for 1 minute to produce uniform, stable film. Film was then cured
directly at 200°C or higher for thirty minutes. Film was then washed and rinsed with
cyclohexanone and/or acetone. The film was spin-dried at 1500 rpm for one minute. Oven-dried film at 150°C for 2 hours to produce an approximately 5000A thin film
dielectric.
Example IV
Prepared poly(4-vinylbenzylchloride) by polymerizing 4-vinylbenzylchloride with a polymerization initiator such as azo(bisisobutyronitrile) in 1 ,2-dichloroethane or 1 ,4- dichlorobutane. The solution was heated to 70°C for sixteen hours and polymer
precipitated with methanol or isopropanol. The polymer was isolated and triturated under methanol (two to three times) to produce a tan solid which was dried at 70°C in an
oven. Prepared reaction solution by mixing and dissolving polystyrene (0.180g, 1.8 mmoles, MW 50,000) and poly(4-vinylbenzylchloride) (0.030g, 0.18 mmoles) in 1,4- dichlorobutane (2.0 mL) until solution was homogenous. Added tin tetrachloride solution (0.2-0.4mL, 0.3 mmoles, IM in dichloromethane) to solution and mixed. Dispensed solution onto wafer substrate, and spin-coated at 1500 rpm for 20 seconds producing a film. Remaining solvent was evaporated at 150°C to produce an approximately 3500A
film. Film was aged at 150°C for 3 hours.
Example V
Prepared poly(4-vinylbenzylchloride) by polymerizing 4-vinylbenzylchloride with a polymerization initiator such as azo(bisisobutyronitrile) in 1,2-dichloroethane or 1,4- dichlorobutane. The solution was heated to 70°C for sixteen hours and polymer
precipitated with methanol or isopropanol. The polymer was isolated and triturated under methanol (two to three times) to produce a tan solid which was dried at 70°C in an
oven. Prepared reaction solution by mixing and dissolving poly(2,6-dimethyl-l,4- phenyleneoxide) (0.160g, 1.3 mmoles) and poly(4-vinylbenzylchloride) (0.1 OOg, 0.66 mmoles) in 1 ,4-dichlorobutane (2.0 mL) until solution was homogenous. Added tin tetrachloride solution (0.2-0.4mL, 0.3 mmoles, IM in dichloromethane) to solution and mixed. Dispensed solution onto wafer substrate, and spin-coated at 1500 rpm for 10 seconds producing a liquid film. Film was then aged at 150°C for three hours. Film was
washed and rinsed with solvent (cyclohexanone and/or acetone). The film was spin-dried at 1500 rpm for one minute. Oven-dried film at 150°C for 2 hours to produce a thin film
dielectric. Example VI
Prepared poly(styrene-co-4-vinylbenzylchloride) co-polymer by mixing 4- vinylbenzylchloride (1-100 mole %) with styrene (0-99 mole %) in 1,2-dichloroethane or 1,4-dichlorobutane. A polymerization initiator such as azo(bisisobutyronitrile) was added to the solution. The solution was heated to 70°C for sixteen hours and polymer
precipitated with methanol or isopropanol. The co-polymer was isolated and triturated under methanol (two to three times) to produce a white to tan solid which was dried at 70°C in an oven. The co-polymer (0.300 g) was dissolved in 1,4-dichlorobutane and tin
tetrachloride (0.1-0.5 mL, 0.3 mmoles, IM solution in dichloromethane) was added. The solution was dispensed onto a wafer substrate and spin-coated at 1500 rpm for 10 seconds to produce a liquid film.
Solvent was evaporated at 150°C for 1 minute to produce uniform, stable film. Film was
then aged at 150°C for three hours. Film was then washed and rinsed with cyclohexanone
and/or acetone. The film was spin-dried at 1500 rpm for one minute. Oven-dried film at 150°C for 2 hours to produce an approximately 3500A thin film dielectric.
Example VII
Prepared reaction solution by mixing and dissolving poly(2,6-dimethyl-l,4- phenyleneoxide) (0.163 g, 1.36 mmoles) and p-dichloroxylene (0.237 g, 1.36 mmoles) in 1,4-dichlorobutane (2.0 mL) until solution was homogenous. Added tin tetrachloride (0.2- 0.4mL, 0.3 mmoles, IM in dichloromethane) to solution and mixed. Dispensed solution onto wafer substrate, and spin-coated at 1500 rpm for 10 seconds producing a liquid film. Solvent was evaporated at 150°C for 1 minute to produce uniform, stable film. Film was
then aged at 150°C for three hours. Film was washed and rinsed with solvent
(cyclohexanone and/or acetone). The film was spin-dried at 1500 rpm for one minute.
Oven-dried film at 150°C for 2 hours to produce a thin film dielectric.
Example VUI
Prepared polymer solution by mixing and dissolving polystyrene (0.149 g, 1.43 mmoles,
MW 125,000) and p-dichloroxylene (0.250 g, 1.43 mmoles) in 1,4-dichlorobutane (2.0 mL) until solution was homogenous. Added tin tetrachloride (0.2-0.4mL, 0.3 mmoles,
IM in dichloromethane) to solution and mixed. Dispensed solution onto wafer substrate, and spin-coated at 1500 rpm for 10 seconds producing a liquid film. Transferred wafer and film into solvent-saturated environment of 1 ,4-dichlorobutane. Film was aged at 70-
100°C for three hours. Film was washed and rinsed with cyclohexanone and/or acetone.
The film was spin-dried at 1500 rpm for one minute. Oven-dried film at 150°C for 2
hours to produce 5000A thin film dielectric. Dielectric film was cured at 300° or higher
for thirty minutes.
The following chart summarizes ranges and preferred ranges for several variables and parameters of the processes described herein:
Process Variables and Ranges
Figure imgf000020_0001
The dielectric polymer layers of the present invention are generally compatible with semiconductor device fabrication process steps, such as film deposition and curing, etching, electroplating, and chemical-mechanical polishing. Mechanical properties of these dielectric polymers, such as modulus, compressive strength, adhesion and cohesion, can be tailored by the choice of reactants and reaction conditions, such as the type of solvent, reaction temperature, and reaction time. Typically, dielectric polymers of the present invention demonstrate thermal stability in excess of 300°C and good isothermal stability at elevated temperatures, and can exhibit Tg greater than 400°C. The elastic modulus of these dielectric polymers is typically in excess of 5 GPa. The hardness of a film is typically around 0.3 Gpa, as measured by nanoindentation. And, the dielectric constant of these polymers is typically 2.5 or below.
The scope of the present invention is defined by the claims that follow. Those of ordinary skill in the art will recognize that numerous variations, modifications and improvements, may be made to the embodiments described above and still fall within the scope of the invention as claimed.

Claims

CLAIMSWhat is claimed is:
1. A semiconductor device comprising: a substrate; an interconnect on the substrate; and a dielectric layer surrounding the interconnect, the dielectric layer comprising a dielectric polymer formed by: dispensing a reaction solution on the substrate, the reaction solution comprising a polymer precursor, a crosslinking agent, and a solvent; reacting the polymer precursor with the crosslinking agent on the substrate; and removing the solvent from the reaction solution.
2. The semiconductor device of claim 1 wherein the polymer precursor includes an organic and an inorganic compound.
3. The semiconductor device of claim 1 wherein the polymer precursor comprises a compound having a molecular weight in a range of about 50,000 g/mol to about 150,000 g/mol.
4. The semiconductor device of claim 1 wherein the polymer precursor is selected from the group consisting of: boron containing organic compounds, silicon containing organic compounds, and aluminum containing organic compounds.
5. The semiconductor device of claim 1 wherein the crosslinking agent includes an organic and an inorganic compound.
6. The semiconductor device of claim 1 wherein the reaction solution comprises the crosslinking agent in a range of about 1 to about 20 percent by weight.
7. The semiconductor device of claim 1 wherein the polymer precursor and the crosslinking agent include an aromatic species.
8. The semiconductor device of claim 1 wherein the solvent comprises a combination of different solvents.
9. The semiconductor device of claim 1 wherein the solvent has a boiling point in a range of about 80°C to about 250°C.
10. The semiconductor device of claim 1 wherein the dielectric polymer has a dielectric constant in a range of about 3.0 to about 1.0.
11. An electronic package comprising: a fibrous mat; and a dielectric material, the dielectric material comprising a dielectric polymer formed by: applying a reaction solution to the fibrous mat, the reaction solution comprising a polymer precursor and a crosslinking agent in a solvent; reacting the polymer precursor with the crosslinking agent within the fibrous mat; and removing the solvent from the reaction solution.
12. The semiconductor device of claim 11 wherein the solvent comprises a combination of different solvents.
13. The semiconductor device of claim 11 wherein the solvent has a boiling point in a range of about 80°C to about 250°C.
14. The semiconductor device of claim 11 wherein the dielectric polymer has a dielectric constant in a range of about 3.0 to about 1.0.
15. The semiconductor device of claim 11 wherein the polymer precursor includes an organic and an inorganic compound.
16. The semiconductor device of claim 11 wherein the polymer precursor is selected from the group consisting of: boron containing organic compounds, silicon containing organic compounds, and aluminum containing organic compounds.
17. The semiconductor device of claim 11 wherein the crosslinking agent includes an organic and an inorganic compound.
18. A process for forming a semiconductor device, the process comprising: dispensing a reaction solution on a substrate, the reaction solution comprising a polymer precursor, a crosslinking agent and a solvent; reacting the polymer precursor with the crosslinking agent on the substrate; and removing the solvent from the reaction solution.
19. The process of claim 18 wherein dispensing the reaction solution comprises spin-coating the reaction solution on the substrate.
20. The process of claim 18 wherein the reaction solution further comprises a catalyst.
21. The process of claim 18 wherein the step of reacting the reaction solution comprises irradiating the reaction solution with ultraviolet radiation.
22. The process of claim 21 wherein the reaction solution further comprises a catalyst and the catalyst comprises a photoinitiator.
23. The process of claim 21 wherein the reaction solution further comprises a catalyst and the catalyst comprises a photosensitizer.
24. The process of claim 21 wherein the crosslinking agent comprises a compound with a vinyl group.
25. The process of claim 18 wherein reacting the reaction solution comprises heating the reaction solution.
26. The process of claim 25 wherein the cross-linking agent comprises at least two leaving groups attached to benzylic carbons.
27. The process of claim 18 wherein removing the solvent comprises a solvent exchange step.
28. The process of claim 18 wherein removing the solvent includes heating the substrate.
29. The process of claim 18 wherein the solvent is removed prior to reacting the polymer precursor with the crosslinking agent.
30. The process of claim 18 wherein the solvent is removed simultaneously with reacting the polymer precursor with the crosslinking agent.
31. A process for forming a semiconductor device, the process comprising: first dispensing a reaction solution on a substrate, the reaction solution comprising a polymer precursor, a crosslinking agent and a solvent; after dispensing the reaction solution on the substrate, reacting the polymer precursor with the crosslinking agent on the substrate; after reacting the polymer precursor with the crosslinking agent on the substrate, removing the solvent from the reaction solution.
32. The process of claim 31 wherein the reaction solution is reacted by aging before removing the solvent.
33. The process of claim 31 wherein the polymer film is cured after removing the solvent.
34. A process for forming a semiconductor device, the process comprising: first dispensing a reaction solution on a substrate, the reaction solution comprising a polymer precursor, a crosslinking agent and a solvent; after dispensing the reaction solution on the substrate, removing the solvent from the reaction solution; after removing the solvent from the reaction solution, reacting the polymer precursor with the crosslinking agent on the substrate.
35. The process of claim 34 wherein the polymer precursor and the crosslinking agent are reacted by aging after the solvent is removed.
36. The process of claim 34 wherein the dielectric polymer film is rinsed after the polymer precursor and the crosslinking agent are reacted.
37. The process of claim 34 wherein the dielectric polymer film is cured after the polymer precursor and the crosslinking agent are reacted.
38. A process for forming a semiconductor device, the process comprising: first dispensing a reaction solution on a substrate, the reaction solution comprising a polymer precursor, a crosslinking agent and a solvent; after dispensing the reaction solution on the substrate, reacting the polymer precursor with the crosslinking agent on the substrate while simultaneously removing the solvent from the reaction solution.
39. A process for forming an electronic package, the process comprising: providing a mat, the mat comprising a plurality of fibers; applying a reaction solution to the mat, the reaction solution comprising a polymer precursor, a crosslinking agent and a solvent; reacting the polymer precursor with the crosslinking agent around the plurality of fibers; and removing the solvent from the mat.
40. The process of claim 39 wherein, before reacting the polymer precursor with the crosslinking agent, the mat having the polymer precursor with the crosslinking agent applied thereto is placed in a press and reacting the polymer precursor with the crosslinking agent is carried out in the press.
41. The process of claim 39 wherein the solvent is removed prior to reacting the polymer precursor with the crosslinking agent.
42. The process of claim 39 wherein the solvent is removed simultaneously with reacting the polymer precursor with the crosslinking agent.
43. A process for forming an electronic package, the process comprising: providing a mat, the mat comprising a plurality of fibers; first applying a reaction solution, the reaction solution comprising a polymer precursor and a crosslinking agent in a solvent to the mat; after applying the reaction solution, reacting the polymer precursor with the crosslinking agent around the plurality of fibers; after reacting the polymer precursor with the crosslinking agent, removing the solvent from the mat.
44. The process of claim 43 wherein the reaction solution is reacted by aging before removing the solvent.
45. The process of claim 43 wherein the dielectric polymer film is cured after removing the solvent.
46. A process for forming an electronic package, the process comprising: providing a mat, the mat comprising a plurality of fibers; first applying a reaction solution, the reaction solution comprising a polymer precursor and a crosslinking agent in a solvent to the mat; after applying the reaction solution, removing the solvent from the mat; then after removing the solvent from the mat, reacting the polymer precursor with the crosslinking agent around the plurality of fibers.
47. The process of claim 46 wherein the polymer precursor and crosslinking agent are reacted by aging after the solvent is removed.
48. The process of claim 46 wherein the dielectric polymer film is rinsed after the polymer precursor and crosslinking agent are reacted.
49. The process of claim 46 wherein the dielectric polymer film is cured after the polymer precursor and crosslinking agent are reacted.
50. A process for forming an electronic package, the process comprising: providing a mat, the mat comprising a plurality of fibers; first applying a reaction solution, the reaction solution comprising a polymer precursor and a crosslinking agent in a solvent to the mat; after applying the reaction solution, reacting the polymer precursor with the crosslinking agent around the plurality of fibers while simultaneously removing the solvent from the mat.
PCT/US2000/018830 1999-07-08 2000-07-10 Semiconductor devices and process for manufacture WO2001004954A1 (en)

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