JP2012114234A - Uv irradiation processing device, and uv curing method of low-k film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a UV irradiation processing device having a vacuum evacuation system which allows the shortening of the time required for evacuating a gaseous matter released by degassing a Low-k film formed on a substrate by UV irradiation, and is arranged so that no abnormal electric discharge occurs, and to provide a UV curing method of a Low-k film.SOLUTION: The UV irradiation processing device includes: a UV irradiation process chamber 2; a substrate-support stage put in the UV irradiation process chamber 2 and having a substrate-heating mechanism 24; a UV irradiation device 22 with a UV light source 21 incorporated therein, and a UV transmission window 23, which are placed in upper portions of the UV irradiation process chamber 2; and a vacuum evacuation system 26 for evacuating the process chamber 2, which has a combination of a pump 26a for low vacuum level for evacuation from the atmosphere to a low vacuum region, and a pump 26b for middle and high vacuum levels for evacuation from the low-vacuum region to a middle or high vacuum region. The UV irradiation processing device is used to thermally cure a Low-k film formed on a substrate S.

Description

  The present invention relates to an ultraviolet irradiation processing apparatus and an ultraviolet curing method for a low-k film, and more particularly to an ultraviolet irradiation processing apparatus and a substrate surface for thermally curing a low-k film on a substrate surface by ultraviolet irradiation in a semiconductor device manufacturing apparatus. The present invention relates to an ultraviolet curing method for a low-k film formed on the substrate.

  2. Description of the Related Art Conventionally, a semiconductor device manufacturing apparatus having an ultraviolet irradiation processing chamber is known. In this case, as an exhaust system in the ultraviolet irradiation processing chamber, a dry pump as an exhaust pump for low vacuum is used in view of cost. However, in this low vacuum exhaust pump, when the substrate is subjected to ultraviolet treatment, it takes time to exhaust the degassing components (for example, organic substances such as oligomers) from the film formed on the substrate surface.

  In addition, the organic matter contained in the degassing component as described above adheres to the inner wall of the ultraviolet irradiation processing chamber, the jig disposed in the processing chamber, or the window for transmitting ultraviolet light. Performance cannot be demonstrated. This is because, in the case of a synthetic quartz window that is normally used as an ultraviolet transmitting window when an ultraviolet lamp is installed in the atmosphere and performing ultraviolet curing, the organic matter adheres to the quartz window, This is because the transmittance of the light source deteriorates and it becomes impossible to irradiate a predetermined amount of ultraviolet rays into the ultraviolet irradiation treatment chamber. On the other hand, for example, ozone cleaning or cleaning gas radical species are known to clean the inside of the ultraviolet irradiation processing chamber, but after this cleaning, a normally used low vacuum pump is irradiated with ultraviolet rays. It takes time to exhaust the processing chamber. Although it is required to perform the ultraviolet irradiation processing time including the exhaustion in a short time, the long exhaust time can be an obstacle for the short-time processing when the ultraviolet irradiation processing apparatus is used.

  There has been proposed a method of cleaning the light transmission window of the ultraviolet irradiation chamber using the radical species of the cleaning gas described above (see, for example, Patent Document 1). This patent document also describes ozone cleaning as a conventional technique. However, Patent Document 1 also suggests a description of what vacuum pump is used for exhausting the ultraviolet irradiation chamber and what means is used to shorten the exhaust time. Nor.

The ultraviolet irradiation processing chamber will be described with reference to FIG. 1 showing an example of a conventional ultraviolet irradiation processing chamber. The ultraviolet irradiation processing chamber 1 is provided with an ultraviolet irradiation device 12 incorporating an ultraviolet light source 11 in the upper part thereof, and a synthetic quartz window 13 for transmitting ultraviolet rays is disposed under the ultraviolet irradiation device. A support stage for the substrate S provided with a heating mechanism 14 is disposed in the lower part. Further, a gas introduction system including mass flow controllers (MFC) 15a and 15b is connected to the side wall of the ultraviolet irradiation processing chamber 1, and the ultraviolet irradiation processing chamber 1 is evacuated to exhaust the inside thereof. System 16 is connected. From this gas introduction system, gases such as Ar, N ₂ , He, and O ₂ are supplied into the ultraviolet irradiation processing chamber 1 to purge and clean the processing chamber, cure the substrate, cool the processing chamber and the substrate, and assist heating. I do. The vacuum exhaust system 16 is configured such that a low vacuum pump 16a such as a dry pump is connected to the ultraviolet irradiation processing chamber 1 through a valve 16b. The substrate S placed on the support stage is driven by the ultraviolet irradiation device 12 and irradiated with ultraviolet rays through the synthetic quartz window 13 to process the film formed on the surface of the substrate S. An organic substance composed of an oligomer having a molecular weight of 1000 or more contained in a degassing component generated from a film formed on the substrate surface by this treatment is applied to the inner wall of the ultraviolet irradiation processing chamber or a jig disposed in the processing chamber. If it adheres, it causes particles, and if it adheres to a synthetic quartz window or the like, it causes a decrease in UV irradiation efficiency. In this case, low molecular weight substances such as porogen can be removed along with the exhaust.

JP 2008-075179 A

  An object of the present invention is to solve the above-mentioned problems of the prior art, and a short degassing component composed of an organic substance such as an oligomer having a molecular weight of 1000 or more generated from a low-k film on the substrate surface by ultraviolet irradiation treatment. An object of the present invention is to provide an ultraviolet irradiation processing apparatus equipped with an evacuation system that can be evacuated over time and an ultraviolet curing method for a low-k film.

  The ultraviolet irradiation processing apparatus according to the present invention is an apparatus for processing a low-k film formed on a substrate by ultraviolet irradiation, which is equipped with a vacuum exhaust system. An ultraviolet transmission window is disposed under the ultraviolet irradiation apparatus, a substrate support stage having a heating mechanism is disposed below the ultraviolet irradiation processing chamber, and the ultraviolet irradiation processing chamber includes: A vacuum exhaust system for evacuating the interior, combining a low vacuum pump for reducing the vacuum from the atmosphere to a medium / high vacuum pump for exhausting from the low vacuum area to the medium / high vacuum. A vacuum exhaust system is connected.

  The ultraviolet irradiation processing apparatus includes a switching mechanism for switching between a low vacuum pump and a medium / high vacuum pump according to a substrate processing process.

  In the ultraviolet irradiation processing apparatus, each of the low vacuum pump and the middle / high vacuum pumps in the middle of the vacuum exhaust system path connecting the low vacuum pump and the middle / high vacuum pump and the ultraviolet irradiation processing chamber. A pressure control mechanism is interposed on the downstream side.

  In the ultraviolet irradiation apparatus, the low vacuum pump is a dry pump, and the medium / high vacuum pump is a turbo molecular pump.

  In the ultraviolet irradiation processing apparatus, the pressure control mechanism is a conductance variable valve.

  In the ultraviolet curing method of the low-k film of the present invention, a substrate having a film made of a low-k material on the surface is placed in an ultraviolet irradiation treatment chamber, and the substrate is irradiated with ultraviolet rays using an ultraviolet irradiation device. When ultraviolet curing the Low-k film, a low vacuum pump for making a low vacuum from the atmosphere connected to the ultraviolet irradiation processing chamber and a medium for exhausting from the low vacuum region to a medium / high vacuum. -Using an evacuation system combined with a high vacuum pump, the ultraviolet irradiation chamber is set to a pressure of 1E-5 to 1000 Pa and heat-cured at a temperature of 350 to 440 ° C.

  According to the present invention, by using a vacuum exhaust system that combines a low vacuum pump for making a low vacuum from the atmosphere and a medium / high vacuum pump for exhausting from a low vacuum region to a medium / high vacuum, The degassing component composed of oligomers having a molecular weight of 1000 or more from the low-k film on the substrate surface can be exhausted in a short time, and may adhere to the inner wall of the ultraviolet irradiation processing chamber or a jig disposed in the processing chamber. Therefore, there is no generation of particles and no adhesion to a quartz window or the like, so that the ultraviolet irradiation efficiency is not lowered. Of course, low molecular weight substances such as porogen can also be exhausted in a short time.

  Further, according to the present invention, there is an effect that abnormal discharge in the ultraviolet irradiation processing chamber is eliminated.

The block diagram which shows typically the ultraviolet irradiation process chamber by a prior art. The block diagram which shows typically the example of 1 structure of the ultraviolet irradiation process chamber in this invention. The graph which compares and shows the dielectric constant (k value) of the film | membrane obtained by the difference of an exhaust system (Dry pump (DRP) independent and dry pump (DRP) + turbo molecular pump (TMP))). The graph which compares and shows the intensity | strength (Young's modulus: GPa) of the film | membrane obtained by the difference (DRP independent and DRP + TMP) of an exhaust system. The graph which compares and shows the relationship between the dielectric constant (k value) and Young's modulus of the film | membrane obtained by the difference (DRP independent and DRP + TMP) of the exhaust system.

  According to the embodiment of the ultraviolet irradiation processing apparatus of the present invention, the ultraviolet irradiation processing apparatus includes an evacuation system, and is an apparatus for processing a low-k film formed on a substrate by ultraviolet irradiation. An ultraviolet irradiation device incorporating an ultraviolet light source is provided in the upper part of the processing chamber, an ultraviolet transmission window made of quartz or the like is disposed under the ultraviolet irradiation device, and a substrate support stage having a heating mechanism in the lower part of the ultraviolet irradiation processing chamber is provided. A gas introduction system is connected to the side wall of the ultraviolet irradiation processing chamber, and the ultraviolet irradiation processing chamber is a vacuum exhaust system for exhausting the interior of the ultraviolet irradiation processing chamber. Is connected to a vacuum pumping system that combines a dry pump and a turbo molecular pump for evacuating from a low vacuum region to a medium / high vacuum. A pressure control mechanism such as a conductance variable valve is interposed in the middle of the vacuum exhaust system path connecting the UV irradiation processing chamber and the upstream side of each of the dry pump and the turbo molecular pump. A switching mechanism may be provided so that the pump and the turbo molecular pump can be switched according to the substrate processing process.

  There are various types of low-k films formed on a substrate, and the amount of degassing from the films is also unknown. In that case, processing may not be possible with a medium vacuum pump or a high vacuum pump. In this case, a low vacuum pump or the like used as an auxiliary pump by a switching mechanism may be used depending on the process. Can be used. For example, when a large amount of gas is generated from the substrate by UV irradiation or heating and the pressure is lowered when the pressure in the processing chamber temporarily increases, or after exhausting the gas released by the low vacuum pump, It may be possible to switch to a medium / high vacuum pump and exhaust residual gas.

  By providing the switching mechanism as described above, any Low-k film can be handled. The low-k material in the present invention is not particularly limited, and any known low-k material that can be irradiated with ultraviolet rays can be used in the same manner, and degassed components can be exhausted in the same manner.

  According to the embodiment of the ultraviolet curing method of the low-k film according to the present invention, this method includes placing a substrate having a film made of a low-k material on the surface thereof in an ultraviolet irradiation chamber, and When a low-k film is cured by ultraviolet irradiation using an ultraviolet irradiation device, a dry pump for lowering the vacuum from the atmosphere connected to the ultraviolet irradiation processing chamber and a medium / high vacuum from the vacuum region. Using an evacuation system comprising a turbo molecular pump for evacuating to the inside, the pressure inside the ultraviolet irradiation chamber is set to 1E-5 to 1 Pa, heat-cured at a temperature of 350 to 440 ° C., and then low-k In order to make the membrane hydrophobic, it comprises a hydrophobic treatment.

  When the pressure is higher than 1 Pa, the exhaust of degassed components such as oligomers cannot be sufficiently performed, and in order to make it lower than 1E-5, it is generally an ultra-high vacuum region and is a highly versatile turbo molecule. The pump cannot obtain this degree of vacuum, which increases the cost. When the temperature is lower than 350 ° C., the curing effect is insufficient and the performance is deteriorated. When the temperature is higher than 440 ° C., the curing effect is high and the film may be damaged.

  An ultraviolet irradiation processing apparatus according to the present invention will be described below with reference to an ultraviolet irradiation processing chamber shown in FIG. 2 showing an example of an apparatus for processing a film made of a low-k material formed on a substrate surface by ultraviolet irradiation. .

The ultraviolet irradiation processing chamber 2 constituting this processing apparatus is provided with an ultraviolet irradiation device 22 incorporating an ultraviolet light source 21 in the upper part thereof, and a quartz window 23 made of, for example, a synthetic quartz window is disposed under the ultraviolet irradiation device, A support stage for the substrate S provided with a heating mechanism 24 is disposed below the ultraviolet irradiation chamber 2. Further, a gas introduction system including mass flow controllers (MFCs) 25a and 25b is connected to the side wall of the ultraviolet irradiation processing chamber 2, and gases such as Ar, N ₂ , He, and O ₂ are irradiated with the ultraviolet irradiation processing chamber 2. It can be supplied into the chamber to perform purging and cleaning of the processing chamber, curing of the substrate, cooling of the processing chamber and the substrate, and heating assist. The ultraviolet irradiation chamber 2 is connected to a vacuum exhaust system 26 for exhausting the interior thereof. The vacuum exhaust system 26 includes a vacuum exhaust system path 26-1 including a low vacuum pump 26a such as a dry pump, and a vacuum exhaust system path 26-1 including a medium / high vacuum pump 26b such as a turbo molecular pump. It is composed of branches. Here, in the present invention, low vacuum means atmospheric pressure to 1 Pa, and medium / high vacuum means 1 to 1E-5 Pa. In other words, with 1 Pa as the threshold value, the higher one is a low vacuum and the lower one is a medium / high vacuum. However, depending on the low vacuum side pump, there is one that can be evacuated to about 0.2 Pa. May use this value as a threshold value. A variable conductance valve 26c (for example, a butterfly valve) and a valve 26d are interposed in this order from the low vacuum pump 26a toward the upstream side in the vacuum exhaust system path 26-1, and an ultraviolet irradiation process is performed. Connected to chamber 2. Further, a variable conductance valve 26e (for example, a butterfly valve, etc.) and a valve 26f as a pressure control mechanism are arranged in this order from the medium / high vacuum pump 26b to the upstream side in the path 26-2 of the vacuum exhaust system. It is interposed and connected to the ultraviolet irradiation treatment chamber 2. The low vacuum pump 26a is connected to the medium / high vacuum pump 26b via a valve 26g. By connecting in this way, the vacuum exhaust system is switched according to the substrate processing process by opening and closing valves (for example, valves 26f and 26g), and the low vacuum pump 26a and the medium / high vacuum pump 26b are combined. An evacuation system can also be used, and a evacuation system with a single low vacuum pump can also be used.

  According to the present invention, by using a low vacuum pump such as a dry pump as an auxiliary pump for the high vacuum pump, the exhaust speed in the ultraviolet irradiation processing chamber 2 is improved, and the degree of vacuum in the processing chamber 2 is increased. It can be improved quickly. That is, by installing a high vacuum pump such as a turbo molecular pump, an exhaust system capable of stabilizing and controlling the degree of vacuum in the processing chamber 2 can be provided. By degassing from the Low-k film or the like, the pressure in the ultraviolet irradiation processing chamber becomes high, but the degree of vacuum is quickly recovered by high vacuum evacuation, and the next ultraviolet curing treatment can be immediately performed.

  By using the ultraviolet irradiation processing chamber configured as described above, the degassing component from the Low-k film formed on the substrate surface can be exhausted in a short time during the ultraviolet irradiation processing. This degassing component varies depending on the type of membrane, but is usually a polymer having a molecular weight of 1000 or more (for example, a polymer derived from a block polymer contained in the material). Such a degassing component is not exhausted even if a vacuum pumping system of a dry pump alone is used, and adheres to an inner wall, a jig, a quartz window or the like in the ultraviolet irradiation processing chamber, and has the above-mentioned adverse effects.

  In addition, depending on the amount of degassed component from the substrate, process processing with a low vacuum pump alone may be effective. In this case, not only the low vacuum pump is used as an auxiliary pump for the high vacuum exhaust pump, but also the operation to the low vacuum pump must be switched so that the process can be performed by the low vacuum pump alone. Therefore, it is possible to deal with processing with various substrates and pressures.

  By setting the ultraviolet irradiation chamber to a high vacuum using the vacuum exhaust system as described above, various abnormal discharges in the ultraviolet chamber can be prevented.

  When performing ultraviolet irradiation processing on a substrate using the processing apparatus shown in FIG. 2, the ultraviolet irradiation device 22 is driven to irradiate the substrate S placed on the support stage with ultraviolet irradiation. The formed Low-k film can be irradiated with ultraviolet rays. By this treatment, the degassing component generated from the Low-k film formed on the substrate does not adhere to the inner wall of the ultraviolet processing chamber or the jig disposed in the processing chamber, so there is no generation of particles, Moreover, since it does not adhere to the quartz window, the ultraviolet irradiation efficiency does not decrease.

  A process for ultraviolet irradiation treatment of a substrate having a film formed using a low-k material using the ultraviolet irradiation treatment apparatus shown in FIG. 2 will be described below.

First, a spin-on type low-k coating material (for example, containing an oligomeric surfactant having a molecular weight of 1000 or more) is applied to the substrate with a spin coater, and prebaked at 80 to 150 ° C. in an ultraviolet treatment chamber. The low-k film thus obtained is irradiated with ultraviolet rays using an ultraviolet irradiation device (for example, irradiation dose: 3600 mW / cm ² · sec), and heat curing treatment is performed at 350 to 440 ° C. with a predetermined pressure. Conduct time.

  At this time, the inside of the ultraviolet irradiation processing chamber is used by using a vacuum exhaust system that combines a low vacuum pump for reducing the vacuum from the atmosphere and a medium / high vacuum pump for exhausting from the low vacuum region to the middle / high vacuum. Exhaust and perform UV cure at a predetermined pressure. Also, using a vacuum exhaust system with a low vacuum pump alone or a combination of a low vacuum pump and a medium / high vacuum pump, a vacuum exhaust system with a low vacuum pump alone, and a low vacuum pump It is also possible to perform ultraviolet curing by evacuating the ultraviolet irradiation processing chamber to a predetermined pressure while switching the vacuum exhaust system combined with the medium / high vacuum pump according to the substrate processing process.

  After the UV irradiation treatment, the low-k film is hydrophobized under conditions of 350 ° C. annealing using HMDS (hexamethyldisilazane) or TMCTS (tetramethylcyclotetrasiloxane) as a hydrophobizing agent. I do.

  In this embodiment, the obtained film characteristics due to the difference in the exhaust system are evaluated.

A spin-on type low-k coating material (coating material containing a siloxane oligomer having a molecular weight of 1000 or more) is applied to the substrate with a spin coater, and the substrate is heated at 80 ° C. in the ultraviolet irradiation chamber shown in FIGS. Pre-baked. The low-k film thus obtained is irradiated with ultraviolet rays using the ultraviolet irradiation apparatus shown in FIGS. 1 and 2 (irradiation dose: 3600 mW / cm ² · sec), and heat-cured at 350 ° C. for 5 minutes. did. At this time, the experiment was conducted by fixing the heat curing temperature of 350 ° C. and the irradiation dose during ultraviolet curing: 3600 mW / cm ² · sec, and changing the pressure during ultraviolet curing in the ultraviolet irradiation treatment chamber.

  That is, using only a dry pump (DRP) at a pressure of E-0 Pa (BG pressure) and combining a dry pump and a turbo molecular pump (main exhaust) (DRP + TMP) E-3 Pa (BG ) Pressure).

  Thereafter, the thermally cured film was subjected to a hydrophobic treatment using HMDS under annealing conditions of 350 ° C. The low-k film thus obtained had a film thickness of 108 nm in the case of DRP, and a film thickness of 118 nm in the case of DRP + TMP.

  The results thus obtained are shown in Table 1 and shown in FIGS. FIG. 3 is a graph showing the dielectric constant of the Low-k film obtained in the case of DRP and DRP + TMP, and FIG. 4 is a graph showing the Young's modulus (GPa) of the Low-k film obtained in the case of DRP and DRP + TMP. FIG. 5 is a graph showing the relationship between the dielectric constant and Young's modulus of the Low-k film obtained in the case of DRP and DRP + TMP.

  As is apparent from Table 1 and FIG. 3, when attention is paid to the k value, it can be seen that the DRP + TMP performed in a lower vacuum can obtain a lower k value than the DRP, and can achieve a good result. Further, as apparent from Table 1 and FIG. 4, it seems that there is not much difference when only the numerical values of strength (Young's modulus) are compared. However, as shown in FIGS. 3 to 5, in view of the difference in the k value, the DRP + TMP has a lower k value, and thus it is considered that the strength is also improved.

  Comparing the case of using the above-described DRP single vacuum exhaust system and the case of using the DRP + TMP vacuum exhaust system, in the former case, the exhaust time of the degassing component is long, and the inner wall of the ultraviolet irradiation treatment chamber and the interior of the chamber are cured. Degassed components adhered to the tool and the quartz window, and the UV irradiation efficiency was poor. In addition, when the vacuum exhaust system of DRP alone was used, abnormal discharge occurred in the ultraviolet irradiation processing chamber, but when the vacuum exhaust system composed of DRP + TMP was used, abnormal discharge did not occur in the ultraviolet irradiation processing chamber. .

  Moreover, although the said process was repeated with the heat processing curing temperature of 300 degreeC, it became higher than the above in the point of k value, and was not preferable.

  In this example, the obtained film characteristics due to the difference in the exhaust system were evaluated.

A spin-on type low-k coating material (coating material containing a siloxane oligomer having a molecular weight of 1000 or more) was applied to the substrate with a spin coater, and the substrate was prebaked at 100 ° C. in an ultraviolet irradiation chamber. The low-k film thus obtained was irradiated with ultraviolet rays using an ultraviolet irradiation device (irradiation dose: 3600 mW / cm ² · sec), and was subjected to thermal curing treatment at 400 ° C. for 5 minutes. At this time, the heat curing temperature of 400 ° C. and the irradiation dose at the time of ultraviolet curing: 3600 mW / cm ² · sec were fixed, and the pressure at the time of ultraviolet curing in the ultraviolet irradiation treatment chamber was changed in the same manner as in the case of Example 1. Went.

  As in the case of Example 1, the results obtained in this manner were a lower k value in the case of DRP + TMP than in the case of DRP alone, and the strength was also improved.

  Further, when DRP alone and DRP + TMP were compared, the same tendency as in Example 1 was observed with regard to the adhesion of degassing components and abnormal discharge in the ultraviolet irradiation chamber.

  Furthermore, although the above process was repeated at a heat treatment curing temperature of 450 ° C., the k value was higher than the above, which was not preferable.

  According to the present invention, a low-k film having a low k value and a high strength can be obtained by subjecting a film made of a low-k material to ultraviolet irradiation treatment, and thus obtained using a low-k material. It can be used in the field of manufacturing semiconductor devices in which the film is subjected to ultraviolet irradiation treatment.

DESCRIPTION OF SYMBOLS 1 Ultraviolet irradiation processing chamber 11 Ultraviolet light source 12 Ultraviolet irradiation apparatus 13 Synthetic quartz window 14 Heating mechanism 15a, 15b Mass flow controller 16 Vacuum exhaust system 16a Low vacuum pump 16b Valve 2 Ultraviolet irradiation processing chamber 21 Ultraviolet light source 22 Ultraviolet irradiation apparatus 23 Quartz window 24 Heating mechanism 25a, 25b Mass flow controller 26 Vacuum exhaust system 26-1, 26-2 Path 26a Low vacuum pump 26b Medium / high vacuum pump 26c, 26e Conductance variable valves 26d, 26f, 26g Valve S Substrate

Claims (6)

In an apparatus for processing a Low-k film formed on a substrate by ultraviolet irradiation, which includes a vacuum exhaust system, an ultraviolet irradiation apparatus incorporating an ultraviolet light source is provided above the ultraviolet irradiation processing chamber. An ultraviolet transmissive window is disposed below, and a substrate support stage having a heating mechanism is disposed below the ultraviolet irradiation processing chamber, and the ultraviolet irradiation processing chamber is evacuated to exhaust the inside thereof. A vacuum exhaust system that is a combination of a low vacuum pump for lowering the vacuum from the atmosphere and a medium / high vacuum pump for exhausting from the low vacuum area to the middle / high vacuum. Ultraviolet irradiation treatment device characterized by. 2. The ultraviolet irradiation processing apparatus according to claim 1, further comprising a switching mechanism so that the low vacuum pump and the medium / high vacuum pump can be switched according to a substrate processing process. Pressure control in the middle of the vacuum exhaust system path connecting the low vacuum pump and medium / high vacuum pump and the ultraviolet irradiation processing chamber, and downstream of the low vacuum pump and medium / high vacuum pump. The ultraviolet irradiation processing apparatus according to claim 1, wherein a mechanism is interposed. The ultraviolet irradiation processing apparatus according to any one of 1 to 3, wherein the low vacuum pump is a dry pump, and the medium / high vacuum pump is a turbo molecular pump. The ultraviolet irradiation processing apparatus according to claim 3 or 4, wherein the pressure control mechanism is a conductance variable valve. When a substrate having a film made of a low-k material on the surface is placed in an ultraviolet irradiation processing chamber, and the substrate is irradiated with ultraviolet rays using an ultraviolet irradiation device, the low-k film is cured by ultraviolet rays. A vacuum exhaust system that combines a low vacuum pump for making a low vacuum from the atmosphere connected to the ultraviolet irradiation chamber and a medium / high vacuum pump for exhausting from a low vacuum region to a medium / high vacuum. A low-k film ultraviolet curing method, wherein the ultraviolet irradiation chamber is set to a pressure of 1E-5 to 1 Pa and heat-cured at a temperature of 350 to 440 ° C.

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