Ultraviolet processor and ultraviolet processing method

Abstract

To provide an ultraviolet processor and an ultraviolet processing method capable of efficiently forming hydroxyl groups by ultraviolet irradiation.SOLUTION: A ultraviolet processor according to one embodiment of the present invention includes an ultraviolet light source, a processing chamber, a gas supply unit, a temperature difference generating mechanism, and a stage. The processing chamber allows ultraviolet light to enter from the ultraviolet light source. The gas supply unit supplies a vapor mixing gas containing mixed gas and water vapor to the processing chamber. The temperature difference generating mechanism creates a temperature difference in the vapor mixing gas within the processing chamber. The stage holds the workpiece in a region where the ultraviolet light is irradiated and where the concentration of water vapor becomes relatively high due to the convection of the vapor mixing gas caused by the temperature difference.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, a method for processing a workpiece such as a substrate by irradiating it with ultraviolet light has been developed. When irradiating the workpiece with ultraviolet light, various gases are supplied around the workpiece. For example, Patent Document 1 describes a configuration capable of introducing multiple types of gases as processing gases into a processing chamber in which the workpiece is placed. Patent Documents 2 and 3 describe processing devices that introduce a gas containing water vapor into the processing chamber. When water vapor is introduced, the ultraviolet light reacts with water molecules, and hydroxyl groups are formed on the surface of the workpiece, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-144913 A [Patent Document 1] International Publication No. 2002 / 036259 [Patent Document 1] JP 2008-43925 A Summary of the Invention [Problem to be solved by the invention]

[0004] By forming hydroxyl groups, it is possible to modify the insulating layer provided on the surface of a workpiece. For example, hydroxyl groups formed on an insulating layer have the effect of increasing 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 irradiating ultraviolet light.

[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 capable of efficiently forming hydroxyl groups by ultraviolet irradiation. [Means for solving the problem]

[0006] In order to achieve the above object, an ultraviolet processing apparatus according to one aspect of the present invention includes an ultraviolet light source, a processing chamber, a gas supply unit, a temperature difference generating mechanism, and a stage. The ultraviolet light is incident on the processing 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 processing chamber. The temperature difference generating mechanism generates a temperature difference in the water vapor mixed gas in the processing chamber. The stage holds a workpiece in a region of the processing chamber where the ultraviolet light is irradiated and 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 processing device, a temperature difference is generated in the water vapor mixed gas supplied to the processing chamber, causing the water vapor mixed gas to convect. The workpiece is held in an area where the concentration of water vapor is relatively high due to this convection. As a result, 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 in, for example, wiring boards.

[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. In this case, the stage may have a holding surface disposed opposite the entrance window across the treatment space and holding the workpiece.

[0011] The processing space may be a space between an upper surface and a lower surface extending in a horizontal direction. In this case, the mixing gas may be a gas having a larger molecular weight than water. The holding surface may form the upper surface of the processing space. The entrance window may form 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 between an upper surface and a lower surface extending in a horizontal direction. In this case, the mixing gas may be a gas having a smaller molecular weight than water. The holding surface may form the lower surface of the processing space. The entrance window may form 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 such 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 of the water vapor mixed gas.

[0019] The ultraviolet ray treatment device may further include a light source chamber for accommodating the ultraviolet ray light source. The temperature difference generating mechanism may include a cooling mechanism for cooling an atmosphere in the light source chamber.

[0020] In an ultraviolet treatment method according to one aspect of the present invention, the workpiece is irradiated with ultraviolet rays by the ultraviolet treatment device. Effect of the Invention

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

[0022] [Figure 1] 1 is a schematic diagram showing a configuration example of an ultraviolet ray treatment apparatus according to a first embodiment of the present invention. [Diagram 2] FIG. 4 is a schematic diagram showing a configuration example of a gas supply unit. [Diagram 3] FIG. 2 is a schematic diagram showing an example of a water vapor concentration gradient caused by convection. [Figure 4] FIG. 13 is a schematic diagram showing an ultraviolet treatment device given as a comparative example. [Diagram 5] FIG. 11 is a schematic diagram illustrating a configuration example of an ultraviolet ray treatment apparatus according to a second embodiment. [Figure 6] FIG. 13 is a schematic diagram illustrating a configuration example of an ultraviolet ray treatment apparatus according to a third embodiment. [Figure 7] FIG. 13 is a schematic diagram showing a configuration example of an ultraviolet ray treatment apparatus according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0024] <First embodiment> [Outline of UV treatment equipment] FIG. 1 is a schematic diagram showing a configuration example of an ultraviolet treatment apparatus according to a first embodiment of the present invention. The ultraviolet treatment apparatus 100 is an apparatus for performing ultraviolet treatment by irradiating ultraviolet rays 1 onto a workpiece W, which is an object to be treated. In this 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 introduced into the ultraviolet treatment apparatus 100 is, for example, a substrate before the formation of a metal wiring pattern.

[0025] The ultraviolet treatment device 100 includes a gas supply unit 10, a lamp house 20, a treatment 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 treatment chamber 30 are connected to form the main body of the ultraviolet treatment device 100. In the following, the vertical direction is referred to as the Z direction, and directions perpendicular to each other in a horizontal plane perpendicular to the vertical direction are 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 piping 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 processing in which the workpiece W is irradiated with ultraviolet rays.

[0027] 2 is a schematic diagram showing a configuration example of a gas supply unit. The gas supply unit 10 humidifies a mixing gas 2 by passing the mixing gas 2 through water and mixes the gas 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 for storing water (H2O). A certain amount of water, which is less than the volume of the tank, is stored in the humidification tank 14. The supply pipe 15 is a pipe for supplying 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 exhaust pipe 16 is a pipe for discharging gas from the humidification tank 14. One end of the exhaust pipe 16 is disposed above the water surface in the humidification tank 14, and the other end of the exhaust pipe 16 is connected to the processing chamber 30. The needle valve 17 is connected between the supply pipe 15 and the exhaust 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 of the humidification tank 14. The mixture gas 2 passes through the water as bubbles and is released into the space above the water surface. In 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 exhausted from the exhaust pipe 16 and supplied to the treatment chamber 30.

[0031] Moreover, 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 mixed gas 4 discharged from the exhaust pipe 16. This makes it possible to adjust the ratio of the mixing gas 2 and the water vapor 3 in the water vapor mixed gas 4. Furthermore, the humidification tank 14 may be configured to be able to adjust the temperature of the stored water. This makes it possible to control the saturated water vapor pressure of the water, and therefore it is possible to accurately adjust the ratio of the mixing gas 2 and the water vapor 3 in the water vapor mixed gas 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, in ultraviolet processing by the ultraviolet processing device 100. In this embodiment, a case where nitrogen gas (N2) is mainly used as the mixing gas 2 will be described.

[0033] The specific configuration of the gas supply unit 10 is not limited. For example, it may be configured so that the mixing gas 2 can be selected from several types of gas. In addition, other gas sources or the like 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 constituting 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 becomes the connection surface 24. The opening 25 is an opening provided in the connection surface 24, and allows the 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 an atmospheric gas for the lamp house 20 is supplied, and is connected to a gas supply source (not shown). The exhaust port 26b is an 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 in the lamp house housing 21. In this embodiment, a light source that emits vacuum ultraviolet light (VUV: Vacuum Ultra Violet) is used as the ultraviolet light source 22. Note that the present invention can be applied even 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 illustrated in FIG. 1. These ultraviolet light sources 22 are connected to a power source (not shown). Note that the number and type of the ultraviolet light sources 22 are not limited.

[0038] The entrance window 23 is made of a material that transmits the ultraviolet ray 1, and is provided at the opening 25 of the lamp house housing 21. For example, a plate-shaped member made of synthetic quartz glass is used as the entrance window 23. As shown in FIG. 1, in the ultraviolet ray processing device 100, the entrance window 23 separates the internal space of the lamp house 20 from the internal space of the processing chamber 30. This allows the atmospheric gas (nitrogen gas, etc.) of the lamp house 20 and the atmospheric gas (water vapor mixed gas 4, etc.) of the processing chamber 30 to be individually controlled. In addition, as described later, a processing space 33 separated by the entrance window 23 is formed in the processing chamber 30. Therefore, the entrance window 23 is a window through which the ultraviolet ray from the ultraviolet ray light source 22 enters the processing 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 onto the stage 40. As shown in Fig. 1, the processing chamber 30 has a processing chamber housing 31 and a support stand 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 with, for example, one side 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 containing 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 containing 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. 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 portion 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 portion 37 is a recess provided in the opposing surface 36 to fit the stage 40. The support base 32 is configured using, for example, a metal plate member, a block member, a structural member, or the like. 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 for holding the workpiece W, and the holding surface 41 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 for adsorbing the workpiece W, a clamp for holding 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 ultraviolet light 1 emitted from the ultraviolet light source 22 is irradiated through the entrance window 23 onto the workpiece W held on the holding surface 41.

[0044] The processing space 33 is an internal space of the processing chamber 30 in which 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, the 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 device 100 shown in FIG. 1, the heater 46 is provided on the stage 40. The heater 46 is embedded inside the stage 40 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 sheath 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 manner, 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, the members in contact with the processing space 33 have relatively high and low temperature portions. As a result, it becomes possible to generate a temperature difference 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 gas 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 the various parts of the ultraviolet treatment device 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. For example, thermocouples are used as these temperature sensors 48, but other types of temperature sensors may also be used. The values ​​detected by the temperature sensors 48 are used, for example, for controlling the heater 46, monitoring the temperature, and the like.

[0050] [UV irradiation of insulating layer 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 constitutes 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., CC, CO, CH, OH, 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. One example of the newly formed functional group is the hydroxyl group (COH). COH is a primary oxidizing functional group that is easily bonded to, for example, copper atoms (Cu).

[0053] In Japanese Patent Application No. 2023-064090, the present inventors have described the action of COH formed in an insulating layer by irradiation with VUV. For example, VUV absorption occurs not only on the surface of the insulating layer but also in a region (hereinafter referred to as the surface region) several tens of nm deep from the surface. The surface region is, for example, a region 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, we consider forming a copper film by a sputtering process on the 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) coming from the sputtering source reacts with COH formed on the insulating layer to form COCu. COCu is a bond that connects 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 mentioned above, VUV irradiation forms COH from the surface to the inside of the insulating layer. Therefore, in the sputtering process, COCu is formed not only on the surface of the insulating layer but also in the surface region, which is the inside of the insulating layer. In this way, by performing UV treatment to form COH 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 nm. In other words, an adhesive interface with a gradation of the bond in the depth direction is formed in the surface region. This makes it possible to significantly improve the adhesive strength between the insulating layer and the copper film.

[0056] When ultraviolet 1 is irradiated onto the insulating layer in the air, oxygen molecules (O2) are excited by ultraviolet 1 as it propagates through the air, and turn into ozone (O3) and ground-state oxygen atoms (O( 1 D )), and excited state oxygen atom (O( 3 P )) are produced. 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) and COOH (carboxy group) on the surface of the insulating layer. Functional groups such as C=O and COOH are difficult to 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 is formed in the insulating layer. This is expected to have the effect of improving the adhesion between the insulating layer and a copper film used as a wiring layer, for example. On the other hand, as the oxidation of the insulating layer progresses, functional groups such as C=O and COOH are formed. In this case, the adhesion between the copper film and the insulating layer, for example, may decrease.

[0058] [Introduction of water vapor mixed gas] One method for increasing the ratio of COH formed in the insulating layer is to introduce water vapor mixed gas 4 into the chamber where the ultraviolet treatment is performed. The water vapor mixed 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 (H2O) 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, OH- reacts with the carbon chains 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 generating COH in the insulating layer.

[0060] In addition, 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 is possible to increase the ratio of COH formed in the insulating layer.

[0061] On the other hand, depending on the configuration of the ultraviolet treatment device, the concentration of water vapor 3 around the insulating layer may decrease or become unstable due to the 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] Therefore, the present inventors have focused on the fact that it is possible to create an area where the concentration of water vapor 3 is relatively high 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 an area 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 in the treatment chamber 30 where the 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] Fig. 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 extending in the horizontal direction. 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, gas that is heated 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 in this way, gravity acts on the gas and convection occurs. By the same principle, when a temperature difference is created in the water vapor mixed gas 4 supplied to the processing space 33, convection occurs in the water vapor mixed gas 4.

[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 according to the molecular weight acts on these two types of gases due to the generation of convection. As a result, the concentration of water vapor 3 and the concentration of mixing gas 2 in the processing space 33 show different distributions. In this disclosure, the molecular weight means the sum of the atomic weights of the gas molecules that make up the gas. Therefore, for gases that are monoatomic molecules (helium, argon, etc.), the atomic weight is the molecular weight as it is.

[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 a high concentration 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 a high concentration on the upper surface 33a side of the processing space 33. In this way, due to the difference in molecular weight (density) of the water vapor 3 and the mixing gas 2 that constitute the water vapor mixed gas 4, a concentration distribution occurs in the processing space 33. 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 mixing gas 2. An example of such a mixing gas 2 is nitrogen gas (molecular weight 28). The density of nitrogen gas in a standard state (1 atmosphere, 0°) is 1.25 g / L. The density of water vapor 3 (molecular weight 18) in the standard state is 0.804 g / L. Therefore, when using a water vapor mixed gas 4 (wet nitrogen gas) in which water vapor 3 and nitrogen gas are mixed, the nitrogen gas having a relatively high density is concentrated on the lower surface 33b side of the processing space 33, and the water vapor 3 having a relatively low density is concentrated on the upper surface 33a side of the processing space 33.

[0069] 3 shows a schematic gradational distribution of the concentration of water vapor 3 generated by convection when the molecular weight of the mixing gas 2 is greater than that of water. The concentration of water vapor 3 is higher as the gradation color becomes darker. 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, but 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 a holding surface 41 that holds the workpiece W. Also, the lower surface 33b of the processing space 33 is formed by an entrance window 23 through which ultraviolet rays 1 are incident. When viewed from the main body of the device, this is a configuration in which the processing chamber 30 is arranged on the upper side and the lamp house 20 is arranged on the lower side.

[0071] With this configuration, it becomes possible to hold the workpiece W in an area where the ultraviolet rays 1 are irradiated and the concentration of the water vapor 3 is relatively high. This makes it possible to stably increase the concentration of the 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] In addition, 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 that reaches the insulating layer decreases. For this reason, for example, it becomes difficult to further oxidize parts where COH has already been formed, and functional groups such as C=O and COOH are less likely to be formed.

[0073] In this way, since the ultraviolet light 1 is irradiated in an atmosphere with a high density (water vapor partial pressure) of the water vapor 3, it is possible to suppress the 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 light 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 in the horizontal direction. 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 in the horizontal direction 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 appropriately performed.

[0075] As shown in FIG. 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 processing 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. In this way, since there are no irregularities on the upper surface 33a, for example, no regions where the concentration of the water vapor 3 is locally high or locally low are generated. As a result, it is possible to maintain the concentration of the water vapor 3 uniform throughout the workpiece W.

[0076] Incidentally, as described above, since the water vapor 3 absorbs the ultraviolet rays 1, in order to irradiate the ultraviolet rays 1 to modify the insulating layer, it is better for the irradiation distance d of the ultraviolet rays 1 in the treatment space 33 to be short. 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 realize an ultraviolet treatment that appropriately modifies the insulating layer.

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

[0078] In this way, the processing space 33 becomes 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 dense on the upper surface 33a side and the mixing gas 2 (nitrogen gas, etc.) is dense 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 lower surface 33b side 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] In the following, an experiment is described in which an insulating layer that has been subjected to ultraviolet treatment using the ultraviolet treatment device 100 and a copper film is formed on the insulating layer to evaluate the adhesion strength between the insulating layer and the copper film. The workpiece W that has been subjected to ultraviolet treatment has an insulating layer formed on a support substrate. CCL (Copper Clad Laminate) is used as the support substrate. An epoxy film is used as the insulating layer.

[0081] The workpiece W was introduced into the ultraviolet processing device 100, and was irradiated with VUV while being supplied with 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 ray 1 was set to 1 mm.

[0082] In addition, a copper film was formed on the workpiece W after the ultraviolet treatment by a sputtering device. The film thickness of the sputtered copper film was 300 nm. Then, 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 adhesion between the insulating layer and the copper film (sputtered copper film + copper plating layer) was evaluated using the annealed samples as the measurement subject. 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 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 experimental results when 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, the method of adjusting the water vapor mixed gas 4 (humidified gas) in this experiment will be described. In this experiment, the experimental equipment was placed in a clean room with the room temperature adjusted to 25°C, and the experimental operation was performed there. The water vapor mixed gas 4 was generated by adding water vapor generated by using a heated ultrasonic atomizer to the mixed gas 2 (original gas). Here, the water to be sprayed was heated to 40°C before being sprayed, and the mist-like water droplets were removed by a hollow fiber air filter. Then, the gas from which the water droplets were removed was passed through a radiator to make it the same temperature as room temperature. In this way, the amount of saturated water vapor decreases due to the decrease in temperature, and a gas with a relative humidity of 100% can be obtained. The gas was mixed with dried mixed gas 2 (dry nitrogen, etc.) at an arbitrary ratio, and the moisture content was measured using a dew point meter just before being introduced into the treatment chamber 30, and then used in the experiment. At this time, the relative humidity of the water vapor 3 was adjusted by adjusting the amount of mixed gas 2 based on the measurement value of the dew point meter.

[0087] [Table 1]

[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] during which VUV is irradiated. 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 experiment numbers 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% intervals. For example, in experiment number 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 water vapor 3 was increased, both the adhesion strength and the O1s ratio increased. For example, there was a large increase in adhesion strength and O1s ratio from experiment number 12 (relative humidity of water vapor 3 20%) to experiment number 14 (relative humidity of water vapor 3 40%). In addition, in experiment number 18 (relative humidity of water vapor 3 80%), the adhesion strength was 0.3 and the O1s ratio was 0.28, both of which were maximum values. In this way, the O1s ratio increases as the adhesion strength increases.

[0091] Furthermore, when the relative humidity of water vapor 3 was higher than that of experiment number 14 (relative humidity of water vapor 3: 40%), the change in adhesion strength and O1s ratio was 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% (experiment numbers 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 realizing sufficient adhesion strength while suppressing the generation of water droplets, 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 experiments 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] [Table 2]

[0095] In the experiments Nos. 21-25 shown in Table (2), the minimum temperature of the treatment space 33 was kept at 30°C, and the maximum temperature (temperature of the heater 46) was set at 50°C, 80°C, 120°C, 150°C, and 180°C to perform ultraviolet treatment. In the experiment No. 21, which had the lowest temperature difference, the adhesion strength was 0.1, which was the lowest. When the maximum temperature (temperature difference) was increased, the adhesion strength and O1s ratio increased. For example, the rate of increase in adhesion strength and O1s ratio was large from the experiment No. 22 (maximum temperature 80°C, temperature difference 50°C) to the experiment No. 23 (maximum temperature 120°C, temperature difference 90°C). In the experiment No. 24 (maximum temperature 150°C, temperature difference 120°C), the adhesion strength was 0.29. The adhesion strength in the experiment No. 25 (maximum temperature 180°C, temperature difference 150°C) was the same as that in the experiment No. 24. Thus, 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 adhesion 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 more and 150° C. or less, and more preferably 100° C. or more and 120° C. or less. 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 mixed gas and adhesion strength] The above description has focused on the case where nitrogen gas is used as the mixing gas 2 having a larger molecular weight than water. Alternatively, an inert gas having a larger molecular weight than 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] Examples of gases with a molecular weight larger than that of water include carbon monoxide (CO) and carbon dioxide (CO2), but these gases have a high absorption of VUV. In addition, air and oxygen gas (O2) contain oxygen molecules that promote the oxidation of the insulating layer, so they should not be used to increase the ratio of COH. In addition, it is considered that process gases such as hydrocarbon gases such as methane and ethane and SF6 are decomposed when irradiated with VUV. For these reasons, it is preferable to use nitrogen gas or a rare gas as the mixed gas 2, as described above.

[0099] Table (3) shows the experimental results when the type of the mixed 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] [Table 3]

[0101] In experiment numbers 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. In experiment number 31, which used neon gas with the smallest molecular weight, the adhesion strength was 0.18, which was smaller than the adhesion strength of 0.29 when nitrogen gas with a larger molecular weight was used (see experiment number 24 in Table (2)). On the other hand, in experiment number 32, which used argon gas with 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 increases as the molecular weight of the mixing gas 2 increases.

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

[0103] [Comparative Example] FIG. 4 is a schematic diagram showing an ultraviolet treatment apparatus given as a comparative example. In the ultraviolet treatment apparatus 110 shown in FIG. 4, a treatment chamber 111 is provided below the main body of the apparatus, and a lamp house 112 is provided above. The treatment chamber 111 is provided with 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 in a state where it is floating from the bottom surface near the center of the treatment space 115. An entrance window 116 is provided on the upper 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 to the workpiece W. A heater 118 is 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 operates, the water vapor mixed gas 4 in the processing space 115 convects, 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 concentration between the water vapor and the nitrogen gas near the center of the processing space 115 where the workpiece W is held.

[0105] [Table 4]

[0106] The table (comparative example) shows the experimental results for samples that were subjected to ultraviolet treatment using the ultraviolet treatment device 110. For example, in experiment numbers 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 by 3 seconds each time from 0 to 18 seconds. Here, the adhesion strength was greatest in experiment number 3, where the VUV irradiation time was set to 6 seconds. This value was similar to the value when the ultraviolet treatment device 100 in FIG. 1 was used (experiment number 12 in table (1)).

[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 near 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 the 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 considered 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 in 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 movement to dry the manufacturing process by using metal sputtering deposition, etc.

[0111] In this embodiment, a region where the concentration of water vapor 3 is high is generated by utilizing convection caused by the temperature difference of the water vapor mixed gas 4, and the workpiece W on which the insulating layer is formed is placed in the region. In this way, by increasing the concentration of water vapor 3 around the workpiece W, 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 ray treatment device according to a second embodiment of the present invention will be described. In the following description, the description of the same configuration and operation as in the ultraviolet ray 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. As long as the mechanism can generate a temperature difference in the water vapor mixed gas 4 in the processing chamber 30, the position of the mechanism is not limited.

[0114] 5 is a schematic diagram showing a configuration example of an ultraviolet ray processing apparatus according to a second embodiment. The ultraviolet ray processing apparatus 200 is an apparatus that is assumed to use a mixed gas 2 having a larger molecular weight than water, and has a processing chamber 30 disposed on the upper side and a lamp house 20 disposed on the lower side. In addition, the ultraviolet ray processing apparatus 200 is provided with a heating unit 60 instead of a heater for heating the stage 40, as compared with the ultraviolet ray processing apparatus 100 shown in FIG.

[0115] The heating unit 60 has a unit housing 61 and a unit heater 62. The unit housing 61 is a housing constituting the heating unit 60, and is configured using, for example, a metal structural member. The unit heater 62 is a heating element 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. The water vapor mixed gas 4 is locally heated by heat exchange between the unit housing 61 heated by the unit heater 62 and the water vapor mixed gas 4. The heating unit 60 is also provided with a temperature sensor 48e for measuring the temperature.

[0116] 1, the heating unit 60 is provided on the upper surface 33a side of the processing space 33 and in the vicinity of the exhaust port 35b. The position where the heating unit 60 is provided is not limited, and the heating unit 60 may be provided on the lower surface 33b side of the processing space 33 or in the vicinity of 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 in 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 using a heating unit] 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] [Table 5]

[0120] In experiment numbers 41-47 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, the adhesion strength and O1s ratio increased as the maximum temperature (temperature difference) was increased, and in experiment number 47 (maximum temperature 240° C., temperature difference 210° C.), both the adhesion strength and O1s ratio were highest.

[0121] In this way, when the heating unit 60 is used, the influence of heating on the workpiece W is smaller than, for example, when 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 case has been described in which a heating mechanism for heating the water vapor mixed gas 4 (heater 46 in FIG. 1 or unit heater 62 in FIG. 5) 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 a configuration example of an ultraviolet ray processing apparatus according to a third embodiment. The ultraviolet ray processing apparatus 300 is an apparatus that is assumed to use a mixing gas 2 having a larger molecular weight than water, and has a processing chamber 30 disposed on the upper side and a lamp house 20 disposed on the lower side. In addition to the ultraviolet ray processing apparatus 100 shown in FIG. 1, the ultraviolet ray processing apparatus 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 constitute 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 device 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, a large temperature difference can be easily generated by combining local cooling and heating. 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 has a cooling pipe 71 and a cooling pipe holder 72. The cooling pipe 71 is a pipe through which a refrigerant flows, and is configured, 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, and holds the cooling pipe 71 so that, for example, the surface of the cooling pipe 71 is exposed. In addition, for example, the cooling pipe holder 72 may be configured as a heat transfer member that mediates heat exchange between the atmospheric 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 inner circumference of the upper side of the space in the lamp house 20. This makes it possible to directly cool not only the atmospheric gas for the lamp house 20 but also the members on the lower surface 33b side of the processing space 33. The configuration of the cooling unit 70 is not limited to this.

[0128] [Example 5: Relationship between temperature difference and adhesion strength when using a heating unit] Table (5) shows the experimental results when 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 (measurement 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] [Table 6]

[0130] In experiment numbers 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. In these experiments, it was found that the adhesion strength and O1s ratio increased when the minimum temperature was lowered, i.e., when the temperature difference was increased. Note that in experiment number 54 (minimum temperature 10°C, temperature difference 140°C) and experiment number 55 (minimum temperature 5°C, temperature difference 145°C), both the adhesion strength and O1s ratio were similar.

[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, and to improve the adhesion strength. In addition, since the ultraviolet light source 22 in the lamp house 20 needs to be cooled to reduce the heat generated by the ultraviolet light source 22, the cooling unit 70 also functions as a mechanism for cooling the ultraviolet light source 22. Conversely, if the device is provided 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 the cooling 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 of the concentration distribution 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 high 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 high 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 in consideration of such concentration distribution.

[0134] 7 is a schematic diagram showing a configuration example of an ultraviolet ray treatment device according to a fourth embodiment. The ultraviolet ray treatment device 400 is a device that is assumed to use a mixing gas 2 having a smaller molecular weight than water. For this reason, in the ultraviolet ray treatment device 400, the treatment chamber 30 is disposed on the lower side and the lamp house 20 is disposed on the upper side. This can also be said to be a configuration in which the ultraviolet ray treatment device 100 shown in FIG. 1 is disposed upside down.

[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. Also, 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 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 using a mixing gas with a molecular weight smaller than that of water] Either hydrogen gas or helium gas is used as the mixing gas 2 having a smaller molecular weight than water. Table (6) shows the results of an experiment conducted by introducing the mixing gas 2 having a smaller molecular weight than 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] [Table 7]

[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 that in the case of the experiment using the ultraviolet treatment device 100 shown in FIG. 1 (see experiment number 24 in Table (2)). This is thought to be because the concentration of nitrogen gas, not water vapor 3, became high around the workpiece W, which reduced the efficiency of generating COH.

[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 smaller molecular weight than water. In these cases, it can be seen that the adhesion strength is significantly improved compared to when nitrogen gas is used. Among these, the adhesion strength in experiment 62, which used hydrogen gas, was the highest, and the value was more than four times that of when nitrogen was used. For example, when hydrogen molecules reach the surface of the workpiece W, they can penetrate into the resin because of their small diffusion coefficient. In this case, the hydrogen molecules become the raw material for C-O-H bonds inside the resin, which is thought to make it possible to further improve the adhesion strength.

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

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

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

[0143] For example, the present invention can be used for various pretreatments such as pretreatment of vacuum deposition (automobile mirrors, etc.), pretreatment of CVD (Chemical Vapor Deposition) (semiconductor elements, etc.), pretreatment of ALD (Atomic Layer Deposition) (all-solid-state batteries, etc.), pretreatment of direct bonding of metal plates and resin plates (fuel cells, etc.), and pretreatment of 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, and a covalent bond with oxygen is formed. This makes it possible to sufficiently improve the adhesion between the resin material and the metal or metal compound. In addition, since the replaced hydrogen has a very small molecular radius, it is absorbed into the resin once and then does not slip through the resin. Therefore, no influence of hydrogen remains.

[0144] Furthermore, the present invention is not limited to the above-mentioned pretreatments, but can be used in any modification treatment performed by forming COH (hydroxyl group) 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 treatment using, for example, a hydrophilic chemical solution. 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 characteristic parts of the present technology described above. That is, the various characteristic parts described in each embodiment may be arbitrarily combined without distinction between the embodiments. In addition, the various effects described above are merely examples and are not limited thereto, and other effects may be exhibited. [Explanation of symbols]

[0146] W…Work 4...Water vapor mixed gas 10...Gas supply section 20…Lamphouse 22...UV light source 23...Entrance window 30…Processing room 33... Processing space 33a…Top surface 33b…Bottom surface 40…Stage 41...Holding surface 46…Heater 60…Heating unit 70…Cooling unit 100, 200, 300, 400...UV treatment equipment

Claims

1. 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 for generating a temperature difference in the water vapor mixed gas in the processing chamber; a stage for holding a workpiece in a region in the processing chamber where the ultraviolet light is irradiated and the concentration of the water vapor is relatively high due to convection of the water vapor mixed gas caused by the temperature difference; An ultraviolet treatment device comprising:

2. The ultraviolet treatment device according to claim 1, The mixing gas is an inert gas. Ultraviolet treatment equipment.

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

4. The ultraviolet treatment device according to claim 3, further comprising: an entrance window through which the ultraviolet light from the ultraviolet light source enters the processing space; The stage has a holding surface that is disposed opposite the entrance window across the processing space and that holds the workpiece. Ultraviolet treatment equipment.

5. The ultraviolet treatment device according to claim 4, The processing space is a space sandwiched between an upper surface and a lower surface extending in a horizontal direction, The mixing gas is a gas having a molecular weight larger than that of water, the holding surface constitutes the upper surface of the processing space, The entrance window constitutes the lower surface of the processing space. Ultraviolet treatment equipment.

6. The ultraviolet treatment device according to claim 5, The mixing gas is any one of nitrogen gas, neon gas, argon gas, krypton gas, and xenon gas. Ultraviolet treatment equipment.

7. The ultraviolet treatment device according to claim 4, The processing space is a space sandwiched between an upper surface and a lower surface extending in a horizontal direction, The mixing gas is a gas having a molecular weight smaller than that of water, the holding surface constitutes the lower surface of the processing space, The entrance window constitutes the upper surface of the processing space. Ultraviolet treatment equipment.

8. The ultraviolet treatment device according to claim 7, The mixing gas is either hydrogen gas or helium gas. Ultraviolet treatment equipment.

9. The ultraviolet treatment device according to claim 4, The distance between the entrance window and the workpiece is 0.1 mm or more and 3 mm or less. Ultraviolet treatment equipment.

10. The ultraviolet treatment device according to claim 4, The processing chamber and the stage are configured such that a surface including the holding surface is substantially flat in the processing space. Ultraviolet treatment equipment.

11. The ultraviolet treatment device according to claim 1, The temperature difference generating mechanism includes a heating mechanism that heats the water vapor mixed gas in the processing chamber. Ultraviolet treatment equipment.

12. The ultraviolet treatment device according to claim 11, The heating mechanism is provided on the stage or in a flow path of the water vapor mixed gas. Ultraviolet treatment equipment.

13. The ultraviolet treatment device according to claim 1, further comprising: A light source chamber is provided to house the ultraviolet light source, The temperature difference generating mechanism includes a cooling mechanism that cools the atmosphere in the light source chamber. Ultraviolet treatment equipment.

14. The ultraviolet ray treatment device according to claim 1 irradiates the workpiece with ultraviolet rays. UV treatment method.

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