Ultraviolet treatment device and ultraviolet treatment method

Abstract

Provided are an ultraviolet treatment device and an ultraviolet treatment method that are capable of efficiently forming a hydroxy group through ultraviolet irradiation.　An ultraviolet treatment device according to one embodiment of the present invention comprises an ultraviolet light source, a treatment chamber, a gas supply unit, a temperature difference generation mechanism, and a stage. Ultraviolet light from the ultraviolet light source enters the treatment chamber. The gas supply unit supplies, to the treatment chamber, a steam-gas mixture containing steam and a gas to be mixed. The temperature difference generation mechanism generates a temperature difference in the steam-gas mixture in the treatment chamber. In the treatment chamber, the stage holds a workpiece in an area which is irradiated with the ultraviolet light and in which the concentration of the steam becomes relatively high through convection in the steam-gas mixture due to the temperature difference.

Description

Ultraviolet treatment device and ultraviolet treatment method

[0001] The present invention relates to an ultraviolet treatment apparatus and an ultraviolet treatment method for treating a workpiece by irradiating it with ultraviolet rays.

[0002] Conventionally, methods have been developed for processing workpieces such as substrates by irradiating them with ultraviolet light. When irradiating the workpiece with ultraviolet light, various gases are supplied around the workpiece. For example, Patent Document 1 describes a configuration that allows multiple types of gases to be introduced as processing gases into a processing chamber in which the workpiece is placed. Furthermore, Patent Documents 2 and 3 describe processing devices that introduce a gas containing water vapor into the processing chamber. When water vapor is introduced, ultraviolet light reacts with water molecules, forming hydroxyl groups on the surface of the workpiece, etc.

[0003] JP 2003-144913 A International Publication No. 2002 / 036259 JP 2008-43925 A

[0004] By forming hydroxyl groups, it is possible to modify insulating layers on the surface of a workpiece. For example, hydroxyl groups formed on an insulating layer have the effect of improving the adhesion of metal to the insulating layer. For this reason, there is a demand for a technology that can efficiently form hydroxyl groups by ultraviolet irradiation.

[0005] In view of the above circumstances, an object of the present invention is to provide an ultraviolet treatment device and an ultraviolet treatment method that can efficiently form hydroxy groups by ultraviolet irradiation.

[0006] To achieve the above object, an ultraviolet treatment apparatus according to one aspect of the present invention includes an ultraviolet light source, a treatment chamber, a gas supply unit, a temperature difference generating mechanism, and a stage. Ultraviolet light is incident on the treatment chamber from the ultraviolet light source. The gas supply unit supplies a water vapor mixed gas containing a mixing gas and water vapor to the treatment chamber. The temperature difference generating mechanism generates a temperature difference in the water vapor mixed gas in the treatment chamber. The stage holds a workpiece in a region of the treatment chamber where the ultraviolet light is irradiated and where the concentration of the water vapor becomes relatively high due to convection of the water vapor mixed gas caused by the temperature difference.

[0007] In this ultraviolet treatment device, a temperature difference is generated in the water vapor mixed gas supplied to the treatment chamber, causing convection of the water vapor mixed gas. This convection holds the workpiece in an area where the water vapor concentration is relatively high. This ensures that a sufficient amount of water vapor is supplied near the workpiece, making it possible to efficiently form hydroxyl groups by ultraviolet irradiation. This makes it possible to improve the adhesion of metals on wiring substrates, for example.

[0008] The mixing gas may be an inert gas.

[0009] The processing chamber may include a processing space to which the water vapor mixed gas is supplied. In this case, the temperature difference generating mechanism may locally heat or cool a member in contact with the processing space.

[0010] The ultraviolet treatment device may further include an entrance window through which the ultraviolet light from the ultraviolet light source enters the treatment space, and in this case, the stage may have a holding surface that is disposed opposite the entrance window across the treatment space and that holds the workpiece.

[0011] The processing space may be a space sandwiched between upper and lower surfaces extending horizontally. In this case, the mixing gas may have a molecular weight greater than that of water. The holding surface may constitute the upper surface of the processing space. The entrance window may constitute the lower surface of the processing space.

[0012] The mixing gas may be any one of nitrogen gas, neon gas, argon gas, krypton gas, and xenon gas.

[0013] The processing space may be a space sandwiched between upper and lower surfaces extending horizontally. In this case, the mixing gas may be a gas having a molecular weight smaller than that of water. The holding surface may constitute the lower surface of the processing space. The entrance window may constitute the upper surface of the processing space.

[0014] The mixing gas may be either hydrogen gas or helium gas.

[0015] The distance between the entrance window and the workpiece may be 0.1 mm or more and 3 mm or less.

[0016] The processing chamber and the stage may be configured so that a surface including the holding surface is substantially flat in the processing space.

[0017] The temperature difference generating mechanism may include a heating mechanism that heats the water vapor mixed gas in the processing chamber.

[0018] The heating mechanism may be provided on the stage or in a flow path for the water vapor mixed gas.

[0019] The ultraviolet treatment device may further include a light source chamber that houses the ultraviolet light source, and the temperature difference generating mechanism may include a cooling mechanism that cools the atmosphere in the light source chamber.

[0020] In an ultraviolet treatment method according to one aspect of the present invention, the ultraviolet treatment device irradiates the workpiece with ultraviolet rays.

[0021] As described above, according to the present invention, it is possible to efficiently form hydroxy groups by ultraviolet irradiation. Note that the effects described here are not necessarily limited to those described herein, and any of the effects described in the present disclosure may be achieved.

[0022] Fig. 1 is a schematic diagram showing a configuration example of an ultraviolet treatment device according to a first embodiment of the present invention; Fig. 2 is a schematic diagram showing a configuration example of a gas supply unit; Fig. 3 is a schematic diagram showing an example of a concentration gradient of water vapor due to convection; Fig. 4 is a schematic diagram showing an ultraviolet treatment device given as a comparative example; Fig. 5 is a schematic diagram showing a configuration example of an ultraviolet treatment device according to a second embodiment; Fig. 6 is a schematic diagram showing a configuration example of an ultraviolet treatment device according to a third embodiment; Fig. 7 is a schematic diagram showing a configuration example of an ultraviolet treatment device according to a fourth embodiment;

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0024] First Embodiment [Overview of Ultraviolet Treatment Apparatus] Fig. 1 is a schematic diagram showing an example of the configuration of an ultraviolet treatment apparatus according to a first embodiment of the present invention. The ultraviolet treatment apparatus 100 is an apparatus that performs ultraviolet treatment by irradiating ultraviolet rays 1 onto a workpiece W, which is an object to be treated. In the present disclosure, the workpiece W is a substrate having an insulating layer made of a resin material formed on its surface. The insulating layer is, for example, a layer that serves as a base for forming a metal wiring pattern. Therefore, the workpiece W that is introduced into the ultraviolet treatment apparatus 100 is, for example, a substrate before the metal wiring pattern is formed.

[0025] The ultraviolet treatment device 100 includes a gas supply unit 10, a lamp house 20, a processing chamber 30, a stage 40, a heater 46, an exhaust unit 47, and a temperature sensor 48. Of these, the lamp house 20 and the processing chamber 30 are connected to form the main body of the ultraviolet treatment device 100. Hereinafter, the vertical direction will be referred to as the Z direction, and directions perpendicular to each other in a horizontal plane perpendicular to the vertical direction will be referred to as the X direction and the Y direction. In FIG. 1 , the up-down direction corresponds to the Z direction, and the left-right direction corresponds to the X direction.

[0026] The gas supply unit 10 is connected to the processing chamber 30 via a predetermined pipe and supplies gas to the processing chamber 30. Specifically, the gas supply unit 10 supplies a water vapor mixed gas 4 containing a mixing gas and water vapor to the processing chamber 30. The water vapor mixed gas 4 is used as an atmospheric gas in an ultraviolet treatment in which the workpiece W is irradiated with ultraviolet rays.

[0027] 2 is a schematic diagram showing an example of the configuration of a gas supply unit 10. The gas supply unit 10 humidifies a mixing gas 2 by passing it through water and mixes it with water vapor 3. The gas supply unit 10 includes a gas source 11, an on-off valve 12, a flow rate controller 13, a humidification tank 14, a supply pipe 15, an exhaust pipe 16, and a needle valve 17.

[0028] The gas source 11 is a supply source that supplies the mixing gas 2. As the gas source 11, for example, a gas cylinder containing the mixing gas 2 or a gas supply line provided in the facility is used. The on-off valve 12 is connected to the gas source 11 and opens and closes the supply path of the mixing gas 2. As the on-off valve 12, a ball valve, a gate valve, or the like is used. The flow rate controller 13 is connected downstream of the on-off valve 12 and controls the flow rate of the mixing gas 2. As the flow rate controller 13, for example, an MFC (Mass Flow Controller) that measures the mass flow rate of the mixing gas 2 and controls the flow rate is used.

[0029] The humidification tank 14 is a tank that stores water (HO). A fixed amount of water that is less than the volume of the tank is stored in the humidification tank 14. The supply pipe 15 is a pipe that supplies the mixing gas 2 to the humidification tank 14. One end of the supply pipe 15 is connected to the flow rate controller 13, and the other end of the supply pipe 15 is disposed in the water stored in the humidification tank 14 (below the water surface). The discharge pipe 16 is a pipe that discharges gas from the humidification tank 14. One end of the discharge pipe 16 is disposed above the water surface in the humidification tank 14, and the other end of the discharge pipe 16 is connected to the processing chamber 30. The needle valve 17 is connected between the supply pipe 15 and the discharge pipe 16 outside the humidification tank 14.

[0030] The mixture gas 2, the flow rate of which is controlled by the flow rate controller 13, is supplied from the supply pipe 15 into the water in the humidification tank 14. The mixture gas 2 turns into bubbles and passes through the water, and is released into the space above the water surface. During this process, a mixture gas of the mixture gas 2 and water vapor 3 (water vapor mixture gas 4) is generated. The water vapor mixture gas 4 that has accumulated above the water surface is discharged from the discharge pipe 16 and supplied to the treatment chamber 30.

[0031] Furthermore, by adjusting the needle valve 17, it is possible to add the mixing gas 2 that has not passed through water to the water vapor mixture 4 discharged from the discharge pipe 16. This makes it possible to adjust the ratio of the mixing gas 2 to the water vapor 3 in the water vapor mixture 4. Furthermore, the humidification tank 14 may be configured to be able to adjust the temperature of the water stored therein. This makes it possible to control the saturated water vapor pressure of the water, and to accurately adjust the ratio of the mixing gas 2 to the water vapor 3 in the water vapor mixture 4.

[0032] The mixing gas 2 is typically an inert gas. Here, the inert gas is a gas that is chemically stable and does not easily react with other elements or compounds, for example, during ultraviolet treatment by the ultraviolet treatment device 100. In this embodiment, a case will be described in which nitrogen gas (N) is mainly used as the mixing gas 2.

[0033] The specific configuration of the gas supply unit 10 is not limited. For example, the gas supply unit 10 may be configured to be able to select the mixing gas 2 from several types of gases. Furthermore, other gas sources may be appropriately provided so that any gas other than the water vapor mixed gas 4 (humidified gas of the mixing gas 2) can be supplied to the processing chamber.

[0034] 1 , the lamp house 20 has a lamp house housing 21, an ultraviolet light source 22, and an entrance window 23, and is a chamber that houses the ultraviolet light source 22 and irradiates ultraviolet light into the processing chamber 30. In this embodiment, the lamp house 20 corresponds to a light source chamber that houses the ultraviolet light source.

[0035] The lamp house housing 21 is a box-shaped housing that constitutes the lamp house 20 and houses the ultraviolet light source 22 therein. The lamp house housing 21 has a connection surface 24 and an opening 25. The connection surface 24 is the outer surface of the lamp house housing 21 to which the processing chamber 30 is connected. In FIG. 1 , the outer surface of the lamp house housing 21 on the upper side in the drawing is the connection surface 24. The opening 25 is provided in the connection surface 24 and is an opening that allows ultraviolet light 1 emitted from the ultraviolet light source 22 to pass through.

[0036] The lamp house housing 21 also has a supply port 26a and an exhaust port 26b. The supply port 26a is a supply port through which atmospheric gas for the lamp house 20 is supplied and is connected to a gas supply source (not shown). The exhaust port 26b is a exhaust port through which the atmospheric gas for the lamp house 20 is exhausted and is connected to a recovery pipe (not shown) or the like. The atmospheric gas for the lamp house 20 is a gas that does not substantially absorb the ultraviolet light emitted by the ultraviolet light source 22, and for example, nitrogen gas or the like is used.

[0037] The ultraviolet light source 22 is a light source capable of emitting ultraviolet light 1 and is provided inside the lamp house casing 21. In this embodiment, a light source that emits vacuum ultraviolet light (VUV) is used as the ultraviolet light source 22. Note that the present invention can also be applied when ultraviolet light 1 other than VUV is used. For example, an excimer lamp or a low-pressure mercury lamp can be used as the ultraviolet light source 22. Three ultraviolet light sources 22 are schematically illustrated in FIG. 1. These ultraviolet light sources 22 are connected to a power source (not shown). Note that the number and type of ultraviolet light sources 22 are not limited.

[0038] The entrance window 23 is made of a material that transmits ultraviolet light 1 and is provided in an opening 25 of the lamp house housing 21. The entrance window 23 is, for example, a plate-shaped member made of synthetic quartz glass. As shown in FIG. 1 , in the ultraviolet treatment device 100, the entrance window 23 separates the internal space of the lamp house 20 from the internal space of the treatment chamber 30. This allows the ambient gas (such as nitrogen gas) in the lamp house 20 and the ambient gas (such as water vapor mixed gas 4) in the treatment chamber 30 to be controlled separately. Furthermore, as will be described later, a treatment space 33 separated by the entrance window 23 is formed in the treatment chamber 30. Therefore, the entrance window 23 allows ultraviolet light from the ultraviolet light source 22 to enter the treatment space 33.

[0039] The processing chamber 30 is a chamber into which ultraviolet light is incident from the ultraviolet light source 22 and ultraviolet processing is performed on the workpiece W. A stage 40, which will be described later, is provided inside the processing chamber 30, and the workpiece W is fixed on the stage 40. As shown in Fig. 1, the processing chamber 30 has a processing chamber housing 31 and a support table 32. The processing chamber 30 also includes a processing space 33 to which a water vapor mixed gas 4 is supplied.

[0040] The processing chamber housing 31 is a box-shaped housing that constitutes the processing chamber 30, and is configured to be able to take in ultraviolet light from the lamp house 20. The processing chamber housing 31 has a structure in which, for example, one side is open, and is connected to the connection surface 24 of the lamp house housing 21 with the open side (the lower side in the figure) facing the entrance window 23 of the lamp house 20.

[0041] The processing chamber housing 31 also has a supply port 35a and an exhaust port 35b. The supply port 35a is a supply port through which the atmospheric gas for the processing chamber 30, including the water vapor mixed gas 4, is supplied, and is connected to the exhaust pipe 16 of the gas supply unit 10 shown in FIG. 2. The exhaust port 35b is an exhaust port through which the atmospheric gas for the processing chamber 30, including the water vapor mixed gas 4, is exhausted, and is connected to the exhaust unit 47. The supply port 35a and the exhaust port 35b are each provided at a position communicating with the processing space 33. Note that the size, shape, etc. of the supply port 35a and the exhaust port 35b are not limited.

[0042] The support base 32 is a member that supports the stage 40 inside the processing chamber housing 31, and has an opposing surface 36 and a groove 37. The opposing surface 36 is a surface that faces the lamp house 20 (the connection surface 24 and the entrance window 23). The support base 32 is configured so that the opposing surface 36 covers a cross section along the horizontal direction (X direction and Y direction) of the internal space of the processing chamber housing 31. The groove 37 is a recess provided in the opposing surface 36 for fitting the stage 40. The support base 32 is configured using, for example, a metal plate member, block member, structural member, etc. The type and material of the member that configures the support base 32 are not limited.

[0043] The stage 40 holds the workpiece W inside the processing chamber 30. The stage 40 has a holding surface 41 that holds the workpiece W, and is fitted into the groove 37 of the support base 32 with the holding surface 41 facing the entrance window 23. Therefore, the holding surface 41 is disposed opposite the entrance window 23 across the processing space 33. The stage 40 is also provided with a holding mechanism (not shown) for holding the workpiece W on the holding surface 41. As the holding mechanism, a vacuum chuck that adsorbs the workpiece W, a clamp that holds the outer edge of the workpiece W, or the like is used. Other than this, the specific configuration of the holding mechanism is not limited. The workpiece W held on the holding surface 41 is irradiated with ultraviolet light 1 emitted from the ultraviolet light source 22 through the entrance window 23.

[0044] The processing space 33 is an internal space of the processing chamber 30 where ultraviolet processing is performed on the workpiece W in an atmosphere of the water vapor mixed gas 4. As shown in FIG. 1, the processing space 33 is a space sandwiched between a surface (lower surface 33b) formed by the connection surface 24 and the entrance window 23 of the lamp house housing 21 and a surface (upper surface 33a) formed by the opposing surface 36 of the support base 32 and the holding surface 41 of the stage 40.

[0045] The heater 46 is a heating element provided inside the processing chamber 30. When the heater 46 is operated, members in contact with the heater 46 and the water vapor mixed gas 4 inside the processing chamber 30 are heated. Therefore, the heater 46 functions as a heating mechanism that heats the water vapor mixed gas 4 inside the processing chamber 30. The heater 46 is connected to a temperature controller (not shown).

[0046] In the ultraviolet treatment apparatus 100 shown in FIG. 1 , the heater 46 is provided on the stage 40. The heater 46 is embedded inside the stage 40, for example, so as to heat the entire stage 40. This makes it possible to heat the workpiece W held on the stage 40, and for example, to perform ultraviolet treatment while heating the workpiece W. As the heater 46, for example, a pipe-shaped heater using an electric heating wire (such as a sheathed heater) is used. The specific configuration of the heater 46 is not limited, and for example, an oil heater or the like may be used.

[0047] In this way, the heater 46 locally heats the members in contact with the processing space 33. In the example shown in FIG. 1 , the stage 40 is locally heated among the members in contact with the processing space 33. Therefore, when the heater 46 operates, relatively high-temperature portions and relatively low-temperature portions are generated in the members in contact with the processing space 33. As a result, a temperature difference can be generated in the water vapor mixed gas 4 in the processing space 33. In this embodiment, the heater 46 corresponds to a temperature difference generating mechanism that generates a temperature difference in the water vapor mixed gas in the processing chamber.

[0048] The exhaust unit 47 is connected to the exhaust port 35b of the processing chamber 30 and exhausts atmospheric gases such as the water vapor mixed gas 4 from within the processing chamber 30. The exhaust unit 47 has a flow meter such as an MFM (Mass Flow Meter) and is connected to an exhaust line (not shown). The configuration of the exhaust unit 47 is not limited, and a pressure gauge, a flow control valve, etc. may be provided.

[0049] The temperature sensors 48 are sensors that measure the temperatures of various parts of the ultraviolet treatment apparatus 100. Here, temperature sensors 48a, 48b, 48c, and 48d are provided on the stage 40, the support base 32, the supply pipe 35a of the treatment chamber 30, and the lamp house housing 21, respectively. These temperature sensors 48 are, for example, thermocouples, but other types of temperature sensors may also be used. The values ​​detected by the temperature sensors 48 are used, for example, to control the heater 46, monitor the temperature, etc.

[0050] [Irradiation of insulating layer with ultraviolet light and generation of functional groups]

[0051] The following describes the effect of irradiating the insulating layer provided on the surface of the workpiece W with ultraviolet light 1. The resin material that makes up the insulating layer contains a chain polymer made of carbon atoms (C), oxygen atoms (O), hydrogen atoms (H), etc. The polymer contains single bonds between atoms (e.g., C-C, C-O, C-H, O-H, etc.) and double bonds (e.g., C=O).

[0052] When an insulating layer is irradiated with ultraviolet light such as VUV, the energy of the ultraviolet light is absorbed by the insulating layer. At this time, part of the energy of the ultraviolet light becomes excitation energy that excites the atoms that make up the polymer. As a result, the bonding state of the polymer changes and new functional groups are formed. An example of the newly formed functional group is a hydroxyl group (COH). COH is a primary oxidized functional group that easily bonds with, for example, copper atoms (Cu).

[0053] In Japanese Patent Application No. 2023-064090, the present inventors have described the effect of COH formed in an insulating layer by VUV irradiation. For example, VUV absorption occurs not only on the surface of the insulating layer but also in a region several tens of nanometers deep from the surface (hereinafter referred to as the surface region). The surface region is, for example, a region extending from the surface of the insulating layer to a depth of about 20 nm to 40 nm. Therefore, when an insulating layer is irradiated with VUV, COH is formed from the surface of the insulating layer to the surface region inside the insulating layer.

[0054] Here, consider forming a copper film by a sputtering process on an insulating layer on which COH has been formed. The copper film may be laminated to a thickness that allows it to be used as a wiring pattern, or it may be used as a seed layer for electrolytic plating. In the sputtering process, Cu (metal) flying from the sputtering source reacts with the COH formed on the insulating layer to form COCu. COCu is a bond connecting the carbon chain C of the polymer and the copper film Cu, and functions as a bond between the insulating layer and the copper film.

[0055] As described above, VUV irradiation forms COH layers from the surface to the interior of the insulating layer. Therefore, in the sputtering process, COCu layers are formed not only on the surface of the insulating layer but also in the surface layer region, which is the interior of the insulating layer. By performing UV treatment to form COH layers before sputtering the copper film, it is possible to form a bond between the insulating layer and the copper film from the surface to a depth of several tens of nanometers. In other words, an adhesive interface with a gradation of the bond in the depth direction is formed in the surface layer region. This significantly improves the adhesive strength between the insulating layer and the copper film.

[0056] When the insulating layer is irradiated with ultraviolet light 1 in the air, oxygen molecules (O2) are excited by ultraviolet light 1 during the process of propagation through the air, and are converted into ozone (O3) and ground state oxygen atoms (O( 1 D )), excited state oxygen atom (O( 3 P These oxygen-derived products promote the oxidation of the insulating layer in which hydroxyl groups (COH) are formed, forming, for example, C=O (carbonyl group) or COOH (carboxy group) on the surface of the insulating layer. Functional groups such as C=O and COOH are functional groups that do not easily bond with copper atoms (Cu).

[0057] In this way, when an insulating layer made of a resin material is irradiated with ultraviolet light 1, COH groups are formed in the insulating layer. This is expected to have the effect of improving adhesion between the insulating layer and a copper film used as, for example, a wiring layer. On the other hand, as oxidation of the insulating layer progresses, functional groups such as C═O and COOH groups are formed. In this case, there is a possibility that adhesion between, for example, the copper film and the insulating layer may decrease.

[0058] [Introduction of Water Vapor Mixture Gas] One possible method for increasing the ratio of COH formed in the insulating layer is to introduce water vapor mixture gas 4 into the chamber where the ultraviolet treatment is performed. The water vapor mixture gas 4 is a humidified gas obtained by mixing water vapor 3 with the mixing gas 2 to humidify it.

[0059] When the water vapor mixed gas is irradiated with ultraviolet light 1, the water molecules (HO) contained in the water vapor mixed gas 4 absorb the ultraviolet light 1 and split into oxidizing hydroxide ions (OH-) and reducing hydrogen ions (H+). Of these, the OH- reacts with the carbon chains and other components that make up the insulating layer (resin material) to form COH. In this way, by using the water vapor mixed gas 4, it is possible to directly supply OH- and increase the efficiency of COH generation in the insulating layer.

[0060] Furthermore, a gas other than oxygen gas is used as the mixing gas 2 with which the water vapor 3 is mixed. This eliminates oxygen gas in the chamber, making it possible to suppress the formation of functional groups such as C=O and COOH. As a result, it becomes possible to increase the proportion of COH formed in the insulating layer.

[0061] On the other hand, depending on the configuration of the apparatus for performing the ultraviolet treatment, it is conceivable that the concentration of the water vapor 3 around the insulating layer may decrease or become unstable due to a density difference between the water vapor 3 contained in the water vapor mixed gas 4 and the mixing gas 2. In this case, even if the water vapor mixed gas 4 is introduced, it is not necessarily possible to efficiently form COH.

[0062] [Water Vapor Concentration Gradient] The present inventors have focused on the fact that a region where the concentration of water vapor 3 is relatively high can be created by generating convection by applying a temperature difference to the water vapor mixed gas 4, and have devised a configuration in which the workpiece W is held in such a region and irradiated with ultraviolet light 1. The concentration gradient of water vapor 3 in the treatment chamber 30 of the ultraviolet treatment device 100 according to the present invention will be described below.

[0063] 1, the ultraviolet treatment device 100 is provided with a temperature difference generating mechanism (heater 46 in this embodiment) that generates a temperature difference in the water vapor mixed gas 4 in the treatment chamber 30. The stage 40 that holds the workpiece W is configured to hold the workpiece W in a region of the treatment chamber 30 where ultraviolet light 1 is irradiated and the concentration of water vapor 3 becomes relatively high due to convection of the water vapor mixed gas 4 caused by the temperature difference.

[0064] 3 is a schematic diagram showing an example of a concentration gradient of water vapor 3 associated with convection. Fig. 3 partially illustrates the processing space 33 formed in the processing chamber 30. The processing space 33 is a space sandwiched between an upper surface 33a and a lower surface 33b that extend horizontally. Here, the upper surface 33a is a surface located vertically above the processing space 33, and the lower surface 33b is a surface located vertically below the processing space 33.

[0065] Generally, heated gas in a container becomes less dense due to thermal expansion and moves to the top of the container. On the other hand, cooled gas has a higher density than heated gas and moves to the bottom of the container. When a temperature difference is created in the gas in the container, gravity acts on the gas, causing convection. By the same principle, when a temperature difference is created in the water vapor mixed gas 4 supplied to the processing space 33, convection of the water vapor mixed gas 4 occurs.

[0066] The water vapor mixed gas 4 is a mixture of two types of gases (water vapor 3 and mixing gas 2) with different molecular weights. Buoyancy corresponding to the molecular weights acts on these two types of gases due to the generation of convection. As a result, the concentrations of water vapor 3 and mixing gas 2 in the processing space 33 exhibit different distributions. Note that in this disclosure, molecular weight refers to the sum of the atomic weights of the gas molecules that make up the gas. Therefore, for gases with monoatomic molecules (such as helium and argon), the atomic weight is the molecular weight.

[0067] Of the water vapor 3 and the mixing gas 2, for example, a gas with a relatively large molecular weight (gas with a relatively large density) has a relatively small buoyancy and its concentration is high on the lower surface 33b side of the processing space 33. Conversely, a gas with a relatively small molecular weight (gas with a relatively small density) has a relatively large buoyancy and its concentration is high on the upper surface 33a side of the processing space 33. As described above, a concentration distribution occurs within the processing space 33 due to the difference in molecular weight (density) between the water vapor 3 and the mixing gas 2 that constitute the water vapor mixed gas 4. Note that although the water vapor 3 and the mixing gas 2 have different concentration distributions, they are not separated.

[0068] In this embodiment, a gas having a molecular weight larger than that of water is used as the mixture gas 2. An example of such a mixture gas 2 is nitrogen gas (molecular weight 28). The density of nitrogen gas under standard conditions (1 atmosphere, 0°C) is 1.25 g / L. The density of water vapor 3 (molecular weight 18) under standard conditions is 0.804 g / L. Therefore, when using a water vapor mixture gas 4 (wet nitrogen gas) obtained by mixing water vapor 3 and nitrogen gas, the nitrogen gas, which has a relatively high density, will have a high concentration on the lower surface 33b side of the processing space 33, while the water vapor 3, which has a relatively low density, will have a high concentration on the upper surface 33a side of the processing space 33.

[0069] 3 shows a gradational representation of the concentration distribution of water vapor 3 generated by convection when the molecular weight of the mixing gas 2 is greater than that of water. The darker the gradation color, the higher the concentration of water vapor 3. As shown in FIG. 3, in the processing space 33, the concentration of water vapor 3 is highest in the region in contact with the upper surface 33a. Note that the concentration of water vapor 3 decreases toward the lower surface 33b, while the concentration of the mixing gas 2 (nitrogen gas, etc.) conversely increases toward the lower surface 33b.

[0070] In this embodiment, the concentration of water vapor 3 is relatively high on the upper surface 33a side of the processing space 33. Therefore, in the ultraviolet processing device 100, the workpiece W is held on the upper surface 33a side of the processing space 33, and ultraviolet rays are incident from the lower surface 33b side. Specifically, the upper surface 33a of the processing space 33 is formed by the holding surface 41 that holds the workpiece W. Furthermore, the lower surface 33b of the processing space 33 is formed by the entrance window 23 through which ultraviolet rays 1 are incident. When viewed from the perspective of the device body, this configuration results in the processing chamber 30 being located on the upper side and the lamp house 20 being located on the lower side.

[0071] With this configuration, it is possible to hold the workpiece W in an area where the ultraviolet rays 1 are irradiated and the concentration of water vapor 3 is relatively high. This makes it possible to stably increase the concentration of water vapor 3 around the insulating layer on the surface of the workpiece W. As a result, the supply amount of hydroxide ions (OH-) is maintained at a high level, making it possible to increase the ratio of hydroxyl groups (COH) formed in the insulating layer.

[0072] Furthermore, due to the high concentration of water vapor 3, the amount of energy consumed to separate water vapor 3 (water molecules) into OH- and H+ increases from the energy of the ultraviolet light 1 irradiated toward the workpiece W. On the other hand, the energy of the ultraviolet light 1 reaching the insulating layer decreases. For this reason, for example, it becomes difficult for a situation to occur in which a portion where COH has already been formed is further oxidized, and functional groups such as C=O and COOH are less likely to be formed.

[0073] In this way, since the ultraviolet rays 1 are irradiated in an atmosphere with a high density (water vapor partial pressure) of water vapor 3, it is possible to suppress a decrease in the ratio of COH. In other words, it is possible to limit the modification of the surface of the workpiece W by the ultraviolet treatment to COH. This can also be said to suppress the progression of the oxidation level in the insulating layer.

[0074] As described above, the upper surface 33a and the lower surface 33b of the treatment space 33 are configured to extend horizontally. This makes it possible to avoid a situation in which a concentration gradient of the water vapor 3 (or the mixed gas 2) occurs along the horizontal direction. In this disclosure, a surface extending horizontally means a surface that is disposed substantially horizontally. Therefore, the upper surface 33a and the lower surface 33b do not need to be completely horizontal, and may be slightly inclined from the horizontal plane as long as the ultraviolet treatment of the workpiece W is properly performed.

[0075] 1, the processing chamber 30 and the stage 40 are configured so that the surface including the holding surface 41 in the processing space 33 (here, the upper surface 33a of the processing space 33) is substantially flat. In the ultraviolet treatment device 100 shown in FIG. 1, the support table 32 and the stage 40 are configured so that the opposing surface 36 of the support table 32 arranged in the processing chamber 30 and the holding surface 41 of the stage 40 are flush with each other. As a result, the upper surface 33a of the processing space 33 is substantially flat. As such, since the upper surface 33a is free of irregularities, there are no regions where the concentration of the water vapor 3 is locally high or locally low. This makes it possible to maintain a uniform concentration of the water vapor 3 throughout the workpiece W.

[0076] As described above, since the water vapor 3 absorbs the ultraviolet rays 1, in order to modify the insulating layer by irradiating the ultraviolet rays 1, it is better to have a short irradiation distance d of the ultraviolet rays 1 in the treatment space 33. Here, the irradiation distance d of the ultraviolet rays 1 is the distance between the entrance window 23 and the workpiece W. In this embodiment, the irradiation distance d is set to 0.1 mm or more and 3 mm or less. By setting the irradiation distance d within this range, it is possible to achieve ultraviolet treatment that properly modifies the insulating layer.

[0077] Furthermore, in order to avoid contact between the entrance window 23 and the workpiece W and easily ensure clearance, it is more preferable that the irradiation distance d be 0.5 mm or more, and in order to achieve a sufficient amount of ultraviolet light, it is more preferable that the irradiation distance d be 2 mm or less. Note that the irradiation distance d is not limited to the above range and may be set appropriately depending on, for example, the type of workpiece W and the power of the ultraviolet light source 22.

[0078] In this way, the processing space 33 is a thin plate-like space. Even in this case, by applying a temperature difference to the water vapor mixed gas 4 by the heater 46, the water vapor mixed gas 4 flows inside the processing space 33 with a gradient concentration (concentration distribution) such that the water vapor 3 is concentrated on the upper surface 33a side and the mixing gas 2 (nitrogen gas, etc.) is concentrated on the lower surface 33b side.

[0079] The narrow processing space 33 allows the water vapor 3 to come into contact with the workpiece W more easily. In addition, a layer with a high concentration of the mixing gas 2 is formed on the side of the lower surface 33b where the ultraviolet rays 1 are incident. The mixing gas 2, which is an inert gas such as nitrogen gas, does not absorb much of the ultraviolet rays 1. Therefore, the layer with a high concentration of the mixing gas 2 functions as a section in the processing space 33 where the ultraviolet rays 1 are absorbed less. This makes it possible to increase the distance (irradiation distance d) between the entrance window 23 and the workpiece W, for example, without reducing the irradiation intensity of the ultraviolet rays 1 on the workpiece W, and ensure an appropriate irradiation distance d.

[0080] The following describes an experiment to evaluate the adhesion strength between an insulating layer and a copper film, using a sample in which a copper film was formed on an insulating layer that had been subjected to ultraviolet treatment using the ultraviolet treatment device 100. The workpiece W that was subjected to ultraviolet treatment had an insulating layer formed on a support substrate. CCL (Copper Clad Laminate) was used as the support substrate, and epoxy film was used as the insulating layer.

[0081] The workpiece W was introduced into the ultraviolet treatment device 100, and VUV was irradiated while supplying the water vapor mixed gas 4. An excimer irradiation device was used as the VUV light source. In the experiment, the irradiation distance d of the ultraviolet light 1 was set to 1 mm.

[0082] Furthermore, a copper film was formed on the workpiece W after the ultraviolet treatment using a sputtering device. The film thickness of the sputtered copper film was 300 nm. Thereafter, a copper plating layer was formed by electrolytic copper plating. The film thickness of the copper plating layer was 30 μm. After the copper plating layer was formed, an annealing treatment was performed.

[0083] The annealed samples were used as the measurement subjects to evaluate the adhesion between the insulating layer and the copper film (sputtered copper film + copper plating layer). In the experiment, a 1 cm wide cut was made in the copper film, and the copper film was peeled off using a peel tester to measure the adhesion strength [N / cm]. The maximum adhesion strength was recorded when the copper film was peeled off at a speed of 50 mm / s.

[0084] In addition, the copper film formed on the insulating layer was peeled off from the insulating layer, and the interface of the copper film was measured by X-ray photoelectron spectroscopy (XPS). From the O1s spectrum measured here, the ratio of the peak indicating COCu (529.9 nm) to the peak indicating C=O (531.6 nm) (hereinafter referred to as the O1s ratio) was calculated. The O1s ratio is the ratio of COH to C=O (carbonyl group) and COOH (carboxy group), and it can be said that the higher the value, the higher the ratio of COH formed in the insulating layer.

[0085] Example 1: Relationship between amount of water vapor and adhesion strength Table (1) shows the results of an experiment in which the amount of water vapor 3 contained in the water vapor mixed gas 4 was changed. In this experiment, wet nitrogen, which is a mixture of nitrogen gas and water vapor 3, was used. Here, the relative humidity of the water vapor 3 at 25°C is used as an index indicating the amount of water vapor 3 in the water vapor mixed gas 4.

[0086] Here, we will explain the method for preparing the water vapor mixed gas 4 (humidified gas) in this experiment. In this experiment, the experimental equipment was placed in a clean room with a temperature controlled at 25°C, and the experimental operations were performed there. The water vapor mixed gas 4 was generated by adding water vapor generated using a heated ultrasonic atomizer to the mixing gas 2 (raw gas). Here, the water to be sprayed was heated to 40°C before spraying, and the mist-like water droplets were removed using a hollow fiber air filter. The gas from which the water droplets were removed was then passed through a radiator to return it to room temperature. In this way, the temperature was reduced, reducing the amount of saturated water vapor, and a gas with a relative humidity of 100% was obtained. This gas was mixed with dried mixing gas 2 (e.g., dry nitrogen) at a desired ratio, and the moisture content was measured using a dew point meter immediately before introduction into the processing chamber 30 before use in the experiment. The relative humidity of the water vapor 3 was adjusted by adjusting the amount of mixing gas 2 based on the measurement value from the dew point meter.

[0087]

[0088] The maximum temperature is the maximum temperature in the processing space 33, and in this case, is the temperature of the stage 40 on which the heater 46 is provided. The minimum temperature is the minimum temperature in the processing space 33. Here, the temperature of the lowest temperature part of the housing (lamp house housing 21 and processing chamber housing 31) facing the processing space 33 was recorded as the minimum temperature. The temperature difference is the temperature difference in the processing space 33, and is the difference between the maximum temperature and the minimum temperature. The VUV irradiation time is the time [seconds] for VUV irradiation. In all of the experiments shown in Table (1), the maximum temperature was 150°C, the minimum temperature was 30°C, the temperature difference was 120°C, and the VUV irradiation time was 6 seconds.

[0089] In Experiments 11-20 shown in Table (1), the relative humidity of the water vapor 3 contained in the water vapor mixed gas 4 was changed from 10% to 100% in 10% increments. For example, in Experiment 11, the nitrogen gas was 90% and the water vapor 3 was 10%, but the adhesion strength was the lowest at 0.07. The O1s ratio was also the lowest at 0.

[0090] As the relative humidity of the steam 3 increased, both the adhesion strength and the O1s ratio increased. For example, the rate of increase in adhesion strength and the O1s ratio was large from experiment number 12 (relative humidity of steam 3: 20%) to experiment number 14 (relative humidity of steam 3: 40%). Furthermore, in experiment number 18 (relative humidity of steam 3: 80%), the adhesion strength was 0.3 and the O1s ratio was 0.28, both of which were maximum values. Thus, the O1s ratio increased as the adhesion strength increased.

[0091] Furthermore, when the relative humidity of water vapor 3 was higher than that of Experiment No. 14 (relative humidity of water vapor 3: 40%), the changes in adhesion strength and O1s ratio were relatively small. In the experiments described below, the relative humidity of water vapor 3 was basically set to 40%. Note that when the relative humidity of water vapor 3 was set to 90% and 100% (Experiments Nos. 19 and 20), it was not possible to measure adhesion strength and O1s ratio.

[0092] From the results of Table (1), it is preferable that the relative humidity of the water vapor 3 in the water vapor mixed gas 4 is 20% or more and 80% or less. Furthermore, for example, from the viewpoint of suppressing the generation of water droplets while realizing sufficient adhesion strength, it is more preferable that the relative humidity of the water vapor 3 in the water vapor mixed gas 4 is 40% or more and 60% or less. Note that the relative humidity of the water vapor 3 in the water vapor mixed gas 4 is not limited to the range described here, and may be set appropriately depending on the type of workpiece W, etc.

[0093] [Example 2: Relationship between temperature difference and adhesion strength] Table (2) shows the results of an experiment in which the temperature difference inside the processing chamber 30 was changed. In all of the experiments shown in Table (2), the relative humidity of the water vapor 3 was 40%, and the VUV irradiation time was 6 seconds.

[0094]

[0095] In Experiments 21-25 shown in Table (2), UV treatment was performed with the minimum temperature of the treatment space 33 maintained at 30°C and the maximum temperatures (heater 46 temperatures) set to 50°C, 80°C, 120°C, 150°C, and 180°C. Experiment 21, which had the lowest temperature difference, had the lowest adhesion strength of 0.1. Increasing the maximum temperature (temperature difference) increased the adhesion strength and O1s ratio. For example, the rate of increase in adhesion strength and O1s ratio was greater from Experiment 22 (maximum temperature 80°C, temperature difference 50°C) to Experiment 23 (maximum temperature 120°C, temperature difference 90°C). Furthermore, Experiment 24 (maximum temperature 150°C, temperature difference 120°C) achieved an adhesion strength of 0.29. The adhesion strength in Experiment 25 (maximum temperature 180°C, temperature difference 150°C) was similar to that in Experiment 24. In this way, when the heater 46 is provided on the stage 40, it has been found that a temperature difference of, for example, about 120° C. is sufficient to improve the adhesive strength.

[0096] From the results of Table (2), when the heater 46 is provided on the stage 40, the temperature difference set in the processing chamber 30 (processing space 33) is preferably 90° C. or higher and 150° C. or lower, and more preferably 100° C. or higher and 120° C. or lower. Note that when the heater 46 is provided on the stage 40 as in this embodiment, the maximum temperature (temperature difference) may be set small, taking into consideration that the workpiece W will also be heated. In addition, the temperature difference in the processing chamber 30 is not limited to the range described here, and may be set appropriately depending on the type of workpiece W, etc.

[0097] Example 3: Relationship between type of mixing gas and adhesion strength The above description has focused on the case where nitrogen gas is used as the mixing gas 2, which has a molecular weight greater than that of water. Alternatively, an inert gas having a molecular weight greater than that of water may be used as the mixing gas 2. In this embodiment, any one of the above-mentioned nitrogen gas, neon gas, argon gas, krypton gas, and xenon gas is used as the mixing gas 2.

[0098] Gases with molecular weights larger than that of water include, for example, carbon monoxide (CO) and carbon dioxide (CO2), but these gases have a high VUV absorption. Furthermore, air and oxygen gas (O2) contain oxygen molecules that promote oxidation of the insulating layer, so they should not be used to increase the COH ratio. Furthermore, hydrocarbon gases such as methane and ethane, and process gases such as SF6, are likely to be decomposed by VUV irradiation. For these reasons, it is preferable to use nitrogen gas or a rare gas as the mixing gas 2, as described above.

[0099] Table (3) shows the results of experiments in which the type of mixing gas 2 was changed. In all of the experiments shown in Table (3), the relative humidity of the water vapor 3 was 40%, the maximum temperature was 150°C, the minimum temperature was 30°C, the temperature difference was 120°C, and the VUV irradiation time was 6 seconds.

[0100]

[0101] In experiments 31-34 shown in Table (3), neon gas (Ne: molecular weight 20), argon gas (Ar: molecular weight 40), krypton gas (Kr: molecular weight 83.7), and xenon gas (Xe: 131.3) were used as the mixing gas 2, respectively. The adhesion strength in experiment 31, which used neon gas, which has the smallest molecular weight, was 0.18, which was smaller than the adhesion strength of 0.29 obtained when nitrogen gas, which has a larger molecular weight, was used (see experiment 24 in Table (2)). On the other hand, in experiment 32, which used argon gas, which has a larger molecular weight than nitrogen gas, the adhesion strength was greater than when nitrogen gas was used. Overall, it was found that the adhesion strength increased as the molecular weight of the mixing gas 2 increased.

[0102] For example, since the molecular weight of neon gas (20) is relatively close to the molecular weight of water (18), it is believed that the effect of increasing the concentration of water vapor 3 was limited. Furthermore, argon gas, krypton gas, and xenon gas have molecular weights sufficiently larger than that of water, and it is believed that they were effective in increasing the concentration of water vapor 3. For example, nitrogen gas is preferably used as the mixing gas 2 in terms of reducing the cost of ultraviolet treatment. Furthermore, argon gas, which is relatively inexpensive among rare gases, may be used in order to further improve adhesion strength compared to nitrogen gas.

[0103] [Comparative Example] Figure 4 is a schematic diagram showing an ultraviolet treatment apparatus as a comparative example. The ultraviolet treatment apparatus 110 shown in Figure 4 has a treatment chamber 111 provided below the apparatus body and a lamp house 112 provided above. The treatment chamber 111 also has a columnar support base 114 that supports from below a stage 113 that holds a workpiece W facing upward. Therefore, the stage 113 is supported near the center of the treatment space 115 in a state where it is floating above the bottom surface. An entrance window 116 is provided on the top surface of the treatment space 115 so as to face the workpiece W (stage 113). Ultraviolet light emitted from an ultraviolet light source 117 in the lamp house 112 passes through the entrance window 116 and is irradiated onto the workpiece W. A heater 118 is also provided on the stage 113.

[0104] A water vapor mixed gas 4 containing nitrogen gas and water vapor 3 is supplied to the processing space 115. In this case, when the heater 118 is operated, convection occurs in the water vapor mixed gas 4 in the processing space 115, and the concentration of water vapor increases near the upper surface of the processing space 115 (the surface along the entrance window 116). On the other hand, the concentration of nitrogen gas increases near the lower surface of the processing space 115 (the surface to which the support table 114 is fixed). It is considered that there is almost no difference in the concentrations of water vapor and nitrogen gas near the center of the processing space 115 where the workpiece W is held.

[0105]

[0106] The table (comparison examples) shows the experimental results for samples that were subjected to ultraviolet treatment using the ultraviolet treatment device 110. For example, in experiments 1-7, the relative humidity of the water vapor 3 was set to a relatively low 20%, the temperature difference was set to 120°C, and the VUV irradiation time was increased in increments of 3 seconds from 0 to 18 seconds. Here, the adhesion strength was greatest in experiment 3, where the VUV irradiation time was set to 6 seconds. This value was similar to the value (experiment 12 in Table (1)) when the ultraviolet treatment device 100 in FIG. 1 was used.

[0107] In Experiments 8, 9, and 10, the VUV irradiation time was set to 6 seconds, and the relative humidity of the water vapor 3 was set to 40%, 60%, and 80%. Even when the relative humidity of the water vapor 3 was changed in this way, the adhesion strength changed unstably around 0.1, but there was no tendency for the adhesion strength to improve as the relative humidity of the water vapor 3 increased.

[0108] As described above, the stage 113 of the ultraviolet treatment device 110 is different from the stage 40 of the ultraviolet treatment device 100 in that it is not configured to hold the workpiece W in an area where the concentration of water vapor 3 is relatively high. For this reason, it is not possible to stably supply high-concentration water vapor 3 to the periphery of the workpiece W, and it is thought that the effect of efficiently forming COH cannot be expected.

[0109] As described above, in the ultraviolet treatment device 100 according to this embodiment, a temperature difference is generated in the water vapor mixed gas 4 supplied to the treatment chamber, causing convection of the water vapor mixed gas 4. This convection holds the workpiece W in an area where the concentration of water vapor 3 is relatively high. As a result, a sufficient amount of water vapor 3 is supplied near the workpiece W, making it possible to efficiently form hydroxyl groups (COH) by ultraviolet irradiation.

[0110] For example, when manufacturing wiring boards for mounting semiconductor elements, etc., there is a demand for technology to increase the adhesive strength between an insulating layer made of a resin material and a wiring layer made of a conductive material such as metal. In recent years, there has also been a trend toward dry manufacturing processes using metal sputtering deposition, etc.

[0111] In this embodiment, convection caused by a temperature difference in the water vapor mixed gas 4 is used to generate an area where the concentration of water vapor 3 is high, and the workpiece W on which the insulating layer is formed is placed in this area. By increasing the concentration of water vapor 3 around the workpiece W in this way, it is possible to increase the efficiency of COH generation by ultraviolet irradiation. This makes it possible to efficiently and stably form COH from the surface of the insulating layer to its inner surface region. Therefore, even if a copper film is directly formed on the surface of the insulating layer by sputtering, for example, it is possible to increase the adhesion strength between the insulating layer and the copper film. As a result, it is possible to significantly improve the reliability of the wiring board.

[0112] Second Embodiment An ultraviolet treatment device according to a second embodiment of the present invention will be described. In the following description, the description of the same components and functions as those of the ultraviolet treatment device 100 described in the above embodiment will be omitted or simplified.

[0113] In the above embodiment, a configuration has been described in which a temperature difference is generated in the water vapor mixed gas 4 in the processing chamber 30 by the heater 46 provided on the stage 40. The location of the mechanism is not limited as long as it generates a temperature difference in the water vapor mixed gas 4 in the processing chamber 30.

[0114] 5 is a schematic diagram showing an example of the configuration of an ultraviolet treatment apparatus according to a second embodiment. The ultraviolet treatment apparatus 200 is an apparatus designed to use a mixture gas 2 having a larger molecular weight than water, with the treatment chamber 30 located on the upper side and the lamp house 20 located on the lower side. Furthermore, compared to the ultraviolet treatment apparatus 100 shown in FIG. 1 , the ultraviolet treatment apparatus 200 is provided with a heating unit 60 instead of a heater for heating the stage 40.

[0115] The heating unit 60 has a unit housing 61 and a unit heater 62. The unit housing 61 is a housing that constitutes the heating unit 60 and is formed using, for example, a metal structural member. The unit heater 62 is a heating element that is provided inside the unit housing 61 and heats the entire unit housing 61. For example, a sheath heater or the like is used as the unit heater 62. Heat exchange occurs between the unit housing 61 heated by the unit heater 62 and the water vapor mixed gas 4, thereby locally heating the water vapor mixed gas 4. The heating unit 60 is also provided with a temperature sensor 48e for measuring its temperature.

[0116] The heating unit 60 heats the water vapor mixed gas 4 and is provided in the flow path of the water vapor mixed gas 4. In the example shown in Fig. 1, the heating unit 60 is provided on the upper surface 33a side of the processing space 33 and near the exhaust port 35b. The position where the heating unit 60 is provided is not limited, and for example, the heating unit 60 may be provided on the lower surface 33b side of the processing space 33 or near the supply port 35a. Alternatively, the heating unit 60 may be provided in the center of the processing space 33.

[0117] In this way, even when the heating unit 60 is provided in the flow path of the water vapor mixed gas 4, a temperature difference can be applied to the water vapor mixed gas 4 in the processing space 33 to cause convection, similar to the case where a heater is provided on the stage 40. In this embodiment, the heating unit 60 corresponds to a temperature difference generating mechanism that generates a temperature difference in the water vapor mixed gas in the processing chamber.

[0118] Example 4: Relationship between temperature difference and adhesion strength when a heating unit is used Table (4) shows the results of an experiment in which the temperature difference inside the processing chamber 30 was changed using the heating unit 60. The samples used in the experiment were the same as those used in Examples 1-3 above. The maximum temperature in Table (4) is the temperature of the heating unit 60, and the minimum temperature is the temperature of the coolest part of the housing facing the processing space 33. In all of the experiments shown in Table (4), the relative humidity of the water vapor 3 was 40%, and the VUV irradiation time was 6 seconds.

[0119]

[0120] In experiment numbers 41 to 47 shown in Table (4), ultraviolet treatment was performed with the minimum temperature of the treatment space 33 kept at 30° C. and the maximum temperatures (temperature of the heating unit 60) set to 50° C., 80° C., 120° C., 150° C., 180° C., 210° C., and 240° C. In these experiments, increasing the maximum temperature (temperature difference) increased the adhesion strength and O1s ratio, and experiment number 47 (maximum temperature 240° C., temperature difference 210° C.) achieved the highest adhesion strength and O1s ratio.

[0121] In this way, when the heating unit 60 is used, the influence of heating on the workpiece W is smaller than when, for example, the stage 40 is heated. This makes it possible to set the temperature of the heating unit 60 at a relatively high temperature, and to increase the temperature difference. This makes it possible to achieve high adhesion between the insulating layer and the copper film.

[0122] Third Embodiment

[0123] In the above embodiment, a heating mechanism (heater 46 in FIG. 1 or unit heater 62 in FIG. 5) for heating the water vapor mixed gas 4 is used as a mechanism for generating a temperature difference in the water vapor mixed gas 4 in the processing chamber 30. A mechanism for locally cooling a member in contact with the processing space 33 may also be used as a configuration for generating a temperature difference in the water vapor mixed gas 4.

[0124] 6 is a schematic diagram showing an example of the configuration of an ultraviolet treatment device according to a third embodiment. The ultraviolet treatment device 300 is a device designed to use a mixture gas 2 having a larger molecular weight than water, with the treatment chamber 30 located on the upper side and the lamp house 20 located on the lower side. In addition to the ultraviolet treatment device 100 shown in FIG. 1, the ultraviolet treatment device 300 is provided with a cooling unit 70 in the lamp house 20.

[0125] The cooling unit 70 is a cooling mechanism that cools the atmosphere inside the lamp house 20. The cooling unit 70 cools the atmosphere gas (e.g., nitrogen gas) for the lamp house 20 inside the lamp house 20. This cools the entrance window 23 and the lamp house housing 21 that form the lower surface 33b of the processing space 33, and as a result, the water vapor mixed gas 4 inside the processing space 33 can be locally cooled.

[0126] 6, in the ultraviolet treatment apparatus 300, the water vapor mixed gas 4 in the treatment space 33 is locally heated by a heater 46 provided on the stage 40. In this manner, by combining local cooling and heating, a large temperature difference can be easily generated. In this embodiment, the cooling unit 70 and the heater 46 of the stage 40 constitute a temperature difference generating mechanism that generates a temperature difference in the water vapor mixed gas in the treatment chamber.

[0127] The cooling unit 70 includes a cooling pipe 71 and a cooling pipe holder 72. The cooling pipe 71 is a pipe through which a refrigerant flows and is formed, for example, using a metal pipe with high thermal conductivity. The cooling pipe holder 72 is a structural member that holds the cooling pipe 71, for example, holding the cooling pipe 71 so that the surface of the cooling pipe 71 is exposed. Alternatively, for example, the cooling pipe holder 72 may be formed as a heat transfer member that mediates heat exchange between the ambient gas in the lamp house 20 and the cooling pipe 71. In the example shown in FIG. 6 , the cooling pipe 71 is provided along the upper inner periphery of the space within the lamp house 20. This allows not only the ambient gas for the lamp house 20 but also components on the lower surface 33b side of the processing space 33 to be directly cooled. The configuration of the cooling unit 70 is not limited to this.

[0128] Example 5: Relationship between temperature difference and adhesion strength when a heating unit is used Table (5) shows the results of an experiment in which the temperature difference inside the processing chamber 30 was changed using the cooling unit 70. The samples used in the experiment were the same as those used in Examples 1-3 above. The maximum temperature in Table (5) is the temperature of the stage 40, and the minimum temperature is the temperature (measured value of the temperature sensor 48d) of the lamp house housing 21 that constitutes the lower surface 33b of the processing space 33. The minimum temperature was changed by controlling the temperature of the cooling unit 70. The relative humidity of the water vapor 3 was 40%, and the VUV irradiation time was 6 seconds.

[0129]

[0130] In Experiments 51-55 shown in Table (5), ultraviolet treatment was performed with the maximum temperature of the treatment space 33 kept at 150°C and the minimum temperatures set to 25°C, 20°C, 15°C, 10°C, and 5°C. These experiments revealed that lowering the minimum temperature, i.e., increasing the temperature difference, increased the adhesion strength and O1s ratio. Note that in Experiment 54 (minimum temperature 10°C, temperature difference 140°C) and Experiment 55 (minimum temperature 5°C, temperature difference 145°C), the adhesion strength and O1s ratio both had similar values.

[0131] In this way, by using the cooling unit 70, it is possible to increase the temperature difference of the water vapor mixed gas 4 in the processing space 33, for example, even when the maximum temperature is fixed, thereby improving the adhesion strength. Furthermore, since the ultraviolet light source 22 in the lamp house 20 needs to be cooled to reduce its heat generation, the cooling unit 70 also functions as a mechanism for cooling the ultraviolet light source 22. Conversely, if the apparatus is equipped with a cooling mechanism for the ultraviolet light source 22, it may be configured to increase the temperature difference in the processing chamber 30 by utilizing this mechanism. This makes it possible to sufficiently improve the adhesion strength, for example, even when there is an upper limit to the maximum temperature.

[0132] Fourth Embodiment In the above embodiment, an example has been described in which a gas having a molecular weight larger than that of water is used as the mixing gas 2 constituting the water vapor mixed gas 4. However, the present invention is not limited to this, and the mixing gas 2 may be a gas having a molecular weight smaller than that of water.

[0133] When the molecular weight of the mixing gas 2 is smaller than that of water, the relationship between the concentration distributions of the water vapor 3 and the mixing gas 2 in the processing space 33 is reversed compared to when the molecular weight of the mixing gas 2 is larger than that of water (see FIG. 3 , etc.). That is, the water vapor 3, which has a relatively high density, is concentrated at a higher concentration on the lower surface 33b side of the processing space 33, and the mixing gas, which has a relatively low density, is concentrated at a higher concentration on the upper surface 33a side of the processing space 33. In this embodiment, the processing chamber 30 and the lamp house 20 are configured taking such concentration distributions into consideration.

[0134] 7 is a schematic diagram showing an example of the configuration of an ultraviolet treatment device according to a fourth embodiment. The ultraviolet treatment device 400 is designed to use a mixture gas 2 having a molecular weight smaller than that of water. For this reason, in the ultraviolet treatment device 400, the treatment chamber 30 is located on the lower side and the lamp house 20 is located on the upper side. This configuration can also be said to be the same as the ultraviolet treatment device 100 shown in FIG. 1, but with the top and bottom reversed.

[0135] In this embodiment, the concentration of water vapor 3 is relatively high on the lower surface 33b side of the processing space 33. Therefore, in the ultraviolet treatment device 400, the workpiece W is held on the lower surface 33b side of the processing space 33, and ultraviolet rays are incident from the upper surface 33a side. Specifically, the lower surface 33b of the processing space 33 is formed by a holding surface 41 that holds the workpiece W. Furthermore, the upper surface 33a of the processing space 33 is formed by an entrance window 23 through which ultraviolet rays 1 are incident. With this configuration, it is possible to hold the workpiece W in a region where ultraviolet rays are irradiated and where the concentration of water vapor 3 is relatively high. This makes it possible to stably increase the concentration of water vapor 3 around the insulating layer on the surface of the workpiece W.

[0136] Example 6: Adhesion strength when a mixing gas having a molecular weight smaller than that of water is used Either hydrogen gas or helium gas is used as the mixing gas 2 having a molecular weight smaller than that of water. Table (6) shows the results of an experiment conducted by introducing a mixing gas 2 having a molecular weight smaller than that of water into the ultraviolet treatment device 400 shown in FIG. 7. The samples used in the experiment were the same as those used in Examples 1-3 above. In all of the experiments shown in Table (6), the relative humidity of the water vapor 3 was 40%, the maximum temperature was 150°C, the minimum temperature was 20°C, the temperature difference was 120°C, and the VUV irradiation time was 6 seconds.

[0137]

[0138] Experiment number 61 shown in Table (6) is an experiment conducted for comparison, and is an example in which nitrogen gas, which has a larger molecular weight than water, was used in the ultraviolet treatment device 400. Looking at the results of experiment number 61, the adhesion strength is lower than when the experiment was conducted using the ultraviolet treatment device 100 shown in Figure 1 (see experiment number 24 in Table (2)). This is thought to be because the concentration of nitrogen gas, rather than water vapor 3, became high around the workpiece W, which reduced the efficiency of COH generation.

[0139] In Experiments 62 and 63, hydrogen gas (H2: molecular weight 2) and helium gas (He: molecular weight 4) were used as the mixing gas 2, which has a molecular weight smaller than that of water. In these cases, it can be seen that the adhesion strength was significantly improved compared to when nitrogen gas was used. Among these, Experiment 62, which used hydrogen gas, had the highest adhesion strength, more than four times that of when nitrogen gas was used. For example, when hydrogen molecules reach the surface of the workpiece W, they can penetrate into the resin due to their small diffusion coefficient. In this case, the hydrogen molecules become raw materials for COH bonds inside the resin, which is thought to further improve adhesion strength.

[0140] In this way, even when using a mixing gas 2 having a smaller molecular weight than water, COH can be efficiently formed by holding the workpiece W in an area where the concentration of water vapor 3 is high within the processing chamber 30. Furthermore, when hydrogen gas is used, the hydrogen gas becomes a raw material for COH within the resin, which is expected to have the effect of further increasing adhesion strength.

[0141] <Other Embodiments> The present invention is not limited to the above-described embodiment, and various other embodiments can be realized.

[0142] The above describes the ultraviolet treatment using an ultraviolet treatment device, which is a modification treatment of an insulating layer performed before sputtering a copper film, etc. The present invention is not limited to sputtering film formation, but can be applied to other processes for forming a metal or metal compound on a resin surface.

[0143] For example, the present invention can be used for various pretreatments, such as pretreatment for vacuum deposition (automobile mirrors, etc.), pretreatment for CVD (Chemical Vapor Deposition) (semiconductor devices, etc.), pretreatment for ALD (Atomic Layer Deposition) (all-solid-state batteries, etc.), pretreatment for direct bonding of metal plates and resin plates (fuel cells, etc.), and pretreatment for plating (printed circuit boards, etc.). In all cases, the hydrogen of COH formed on the resin surface is replaced with a metal or metal compound, forming a covalent bond with oxygen. This makes it possible to sufficiently improve the adhesion between the resin material and the metal or metal compound. Note that, because the substituted hydrogen has an extremely small molecular radius, it is absorbed into the resin and then does not pass through the resin. Therefore, no residual effects of hydrogen remain.

[0144] Furthermore, the present invention is not limited to the above-described pretreatments, but can also be used in any modification treatment performed by forming COH (hydroxyl groups) in the insulating layer. For example, by forming a large amount of hydrophilic COH functional groups, it is possible to significantly improve the hydrophilicity of the insulating layer. This makes it possible to properly perform treatments using, for example, hydrophilic chemicals. In addition, the present invention can be applied to any treatment that requires the formation of COH functional groups.

[0145] It is also possible to combine at least two of the features of the present technology described above. That is, the various features described in each embodiment may be arbitrarily combined without distinguishing between the embodiments. Furthermore, the various effects described above are merely examples and are not intended to be limiting, and other effects may also be achieved.

[0146] W: Workpiece 4: Water vapor mixed gas 10: Gas supply unit 20: Lamp house 22: Ultraviolet light source 23: Incident window 30: Processing chamber 33: Processing space 33a: Upper surface 33b: Lower surface 40: Stage 41: Holding surface 46: Heater 60: Heating unit 70: Cooling unit 100, 200, 300, 400: Ultraviolet processing apparatus

Claims

1. An ultraviolet processing apparatus comprising: an ultraviolet light source; a processing chamber into which ultraviolet light is incident from the ultraviolet light source; a gas supply unit that supplies a water vapor mixed gas containing a mixing gas and water vapor to the processing chamber; a temperature difference generating mechanism that generates a temperature difference in the water vapor mixed gas in the processing chamber; and a stage that holds a workpiece in an area in the processing chamber where the ultraviolet light is irradiated and where the concentration of the water vapor becomes relatively high due to convection of the water vapor mixed gas caused by the temperature difference.

2. An ultraviolet ray processing apparatus according to claim 1, wherein the mixing gas is an inert gas.

3. An ultraviolet treatment device according to claim 1, wherein the treatment chamber includes a treatment space to which the water vapor mixed gas is supplied, and the temperature difference generating mechanism locally heats or cools a member in contact with the treatment space.

4. An ultraviolet processing apparatus as claimed in claim 3, further comprising an entrance window through which the ultraviolet light from the ultraviolet light source enters the processing space, and the stage has a holding surface arranged opposite the entrance window across the processing space and for holding the workpiece.

5. An ultraviolet treatment device as claimed in claim 4, wherein the treatment space is a space sandwiched between upper and lower surfaces extending horizontally, the mixing gas is a gas having a larger molecular weight than water, the holding surface constitutes the upper surface of the treatment space, and the entrance window constitutes the lower surface of the treatment space.

6. An ultraviolet treatment device according to claim 5, wherein the mixed gas is any one of nitrogen gas, neon gas, argon gas, krypton gas, and xenon gas.

7. An ultraviolet treatment device as claimed in claim 4, wherein the treatment space is a space sandwiched between upper and lower surfaces extending horizontally, the mixing gas is a gas having a smaller molecular weight than water, the holding surface constitutes the lower surface of the treatment space, and the entrance window constitutes the upper surface of the treatment space.

8. An ultraviolet ray processing apparatus according to claim 7, wherein the mixing gas is either hydrogen gas or helium gas.

9. An ultraviolet ray processing apparatus according to claim 4, wherein the distance between the entrance window and the workpiece is 0.1 mm or more and 3 mm or less.

10. An ultraviolet processing apparatus according to claim 4, wherein the processing chamber and the stage are configured so that a surface including the holding surface in the processing space is substantially flat.

11. An ultraviolet treatment apparatus according to claim 1, wherein the temperature difference generating mechanism includes a heating mechanism for heating the water vapor mixed gas in the treatment chamber.

12. An ultraviolet treatment apparatus according to claim 11, wherein the heating mechanism is provided on the stage or in a flow path of the water vapor mixed gas.

13. An ultraviolet treatment device according to claim 1, further comprising a light source chamber for accommodating said ultraviolet light source, and said temperature difference generating mechanism includes a cooling mechanism for cooling the atmosphere within said light source chamber.

14. An ultraviolet processing method comprising irradiating the work with ultraviolet rays using the ultraviolet processing device according to claim 1.

Images