Surface treatment device, substrate bonding device, surface treatment method, substrate bonding method

Abstract

To provide a technology that can contribute to preventing dust and the like from adhering to the surface of a substrate, preventing moisture from remaining on the surface of the substrate, and facilitating the desired hydrophilization of the surface of the substrate. The apparatus includes a chamber 1 capable of accommodating a substrate 10, a plasma generating unit 2 capable of drawing in a reactive gas into a plasma generating vessel 21 arranged on the outer periphery of the chamber and generating plasma of the reactive gas, an unsaturated hydrocarbon gas supply unit 3 capable of supplying an unsaturated hydrocarbon gas into the chamber 1, an ozone gas supply unit 4 capable of supplying ozone gas into the chamber 1, and a gas exhaust unit 5 capable of drawing in gas within the chamber 1 and discharging it to the outer periphery of the chamber 1. The plasma generating vessel 21 supplies active species generated by the plasma of the reactive gas into the chamber 1 (downstream side).

Description

[Technical field]

[0001] The present invention relates to a surface treatment device, a substrate bonding device, a surface treatment method, and a substrate bonding method, and relates to a technology that can contribute to, for example, making it easier to hydrophilize a substrate as desired and to making it easier to bond a plurality of such hydrophilized substrates together. [Background technology]

[0002] For example, the recent increase in the amount of information transmitted via electronic devices due to the IoT has led to a growing demand for more advanced semiconductor devices. Although technological development for miniaturization and integration of semiconductor devices (Moore's Law) has been progressing, there is now a demand for further technological progress (More Than Moore), and one example of this is the development and practical application of three-dimensional integrated circuits (3D-ICs).

[0003] For example, in the case of a three-dimensional laminate formed by stacking and bonding multiple substrates (substrates to be bonded, such as semiconductor substrates) with different design rules and functions, not only can the integration density of semiconductor devices be increased, but the functions (different functions) of each substrate can be integrated and it can also contribute to reducing wiring distances, so it is believed that various features (new benefits, etc.) can be obtained.

[0004] In joining the bases (objects to be joined) of a three-dimensional laminate, a joining method that does not use adhesives, i.e., a direct joining method, is applied. In recent years, attention has also been drawn to a mode (hybrid joining) that can simultaneously join electrodes, etc. provided on the joining surface of the base.

[0005] Specific examples of direct bonding methods mainly include a method including: (1) a step of forming hydroxyl groups on the surface of a substrate (such as a surface to be bonded that has been planarized in advance as necessary) to make the substrate hydrophilic (hereinafter, appropriately referred to simply as a hydrophilization step); (2) a step of overlapping and laminating two substrates having the hydroxyl groups formed thereon at their surfaces to be bonded (hereinafter, appropriately referred to simply as a lamination step); and (3) a step of causing a dehydration condensation reaction of the hydroxyl groups on the surfaces to be bonded in the laminated state, thereby bonding the substrates to each other at their surfaces to be bonded (hereinafter, appropriately referred to simply as a bonding step).

[0006] In the hydrophilization step, for example, Patent Document 1 discloses a configuration in which the surface of a substrate is plasma-treated (etched, etc.) in a chamber (such as a vacuum chamber) to make it hydrophilic. Patent Document 2 discloses a configuration in which the surface of a substrate is plasma-treated in a chamber to form a reservoir (reservoir indicated by reference numeral 5 in Patent Document 2) for storing moisture and the like, thereby facilitating hydrophilization.

[0007] In the plasma treatments shown in Patent Documents 1 and 2, water treatment using moisture or the like is performed (in Patent Document 1, for example, a treatment using a gas containing moisture is performed as shown in FIG. 8(e), and in Patent Document 2, for example, a treatment of storing water is performed as shown in paragraphs

[0017] and

[0018] ).

[0008] As techniques related to the substrate itself, in addition to the above-mentioned direct bonding method, there are surface treatment methods for modifying the surface of the substrate (e.g., Patent Documents 3 to 6) and film formation methods for forming various thin films on the surface of the substrate by a CVD method (chemical vapor deposition method) or an ALD method (atomic layer deposition method) (e.g., Patent Documents 7 and 8). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 3751872 [Patent Document 2] Patent No. 5955866 [Patent Document 3] Patent No. 4905253 [Patent Document 4] Patent No. 5217951 [Patent Document 5] Patent No. 6052470 [Patent Document 6] Patent No. 6057030 [Patent Document 7] Patent No. 6569831 [Patent Document 8] Patent No. 7056710 Summary of the Invention [Problem to be solved by the invention]

[0010] In a configuration in which the surface of a substrate (surface to be treated, surface to be bonded, etc.) is simply plasma-treated in a chamber as shown in Patent Documents 1 and 2, even if the surface can be made hydrophilic, there is a risk that minute dust particles, etc., will be generated in the chamber and adhere to the surface of the substrate due to collision of ions, etc., from the plasma with the inner wall surface of the chamber, etc. In this way, dust particles, etc., adhering to the surface of the substrate can be removed by water treatment or water washing, etc., but it is considered that moisture is likely to remain on the surface.

[0011] For example, when a substrate is used as a bonding target, if dust or the like as described above is attached to the bonding surface or moisture remains, bonding at the bonding surface may be difficult. As a specific example, in the case of a bonding process, the dehydration condensation reaction is suppressed by the remaining moisture as described above, so that the bonding surfaces may not be bonded as desired.

[0012] The present invention has been made in consideration of the technical problems described above, and has an object to provide a technology that can contribute to making the surface of a substrate more easily hydrophilic as desired by preventing dust and the like from adhering to the surface of the substrate and preventing moisture from remaining on the surface of the substrate. [Means for solving the problem]

[0013] The surface treatment device, substrate bonding device, surface treatment method, and substrate bonding method according to the present invention can contribute to solving the above problems.

[0014] First, one aspect of the surface treatment device includes a chamber capable of accommodating a substrate, a container disposed on the outer periphery of the chamber, a plasma generating unit capable of drawing reactive gas into the container and generating plasma of the reactive gas, an unsaturated hydrocarbon gas supply unit capable of supplying unsaturated hydrocarbon gas into the chamber, an ozone gas supply unit capable of supplying ozone gas into the chamber, and a gas exhaust unit capable of drawing gas in the chamber and discharging it to the outer periphery of the chamber. The container is characterized in that it is capable of supplying activated species generated by the plasma of the reactive gas into the chamber.

[0015] The reactive gas may contain at least one of oxygen, argon, and nitrogen, and the plasma of the reactive gas may be an inductively coupled plasma.

[0016] The chamber may be provided with a shower head at a position facing the substrate accommodated in the chamber, and the shower head may be provided with a supply flow path for the unsaturated hydrocarbon gas from the unsaturated hydrocarbon gas supply unit and a supply flow path for the ozone gas from the ozone gas supply unit.

[0017] The present invention may further include a control unit capable of controlling the output energy of the plasma of the reactive gas in the plasma generating unit, the supply flow rate of the unsaturated hydrocarbon gas in the unsaturated hydrocarbon gas supply unit, the supply flow rate of the ozone gas in the ozone gas supply unit, the exhaust flow rate of the gas in the chamber by the gas exhaust unit, and the pressure in the chamber.

[0018] The control unit may also be capable of controlling the output energy of the plasma of the reactive gas to be set within a range of 50 W to 200 W, and may be capable of controlling the pressure in the chamber to be set within a range of 0.01 Pa to 100 Pa when the plasma of the reactive gas is being generated.

[0019] The control unit may be capable of controlling the pressure in the chamber to be set to 1000 Pa or less in a state in which the unsaturated hydrocarbon gas and the ozone gas are supplied into the chamber.

[0020] One aspect of the substrate joining apparatus is characterized in that it comprises the above-mentioned surface treatment apparatus, the chamber comprising a support portion that supports two of the substrates within the chamber as objects to be joined, and the support portion supports each of the substrates with their respective joining surfaces facing each other and so that they can be moved toward and away from each other in the opposing directions.

[0021] One aspect of the surface treatment method is a method using the surface treatment apparatus, comprising an activation step of activating the surface of the substrate accommodated in the chamber, and a hydroxyl group formation step of forming hydroxyl groups on the surface of the substrate after the activation step.

[0022] The activation step involves drawing a reactive gas into the container to generate plasma of the reactive gas, and supplying active species generated by the plasma of the reactive gas into the chamber, thereby activating the surface of the substrate.

[0023] The hydroxyl group formation process is characterized in that the unsaturated hydrocarbon gas and the ozone gas having an ozone concentration of more than 50 volume % are respectively supplied to the surface of the substrate contained in the chamber, thereby exposing the surface of the substrate to OH radicals generated by a radical reaction between the unsaturated hydrocarbon gas and the ozone gas, thereby forming hydroxyl groups on the surface of the substrate.

[0024] In addition, in the activation step, the activation depth of the surface of the substrate by the active species generated by the plasma of the reactive gas may be within a range of 1 nm to 100 nm.

[0025] One aspect of the substrate joining method is a method for joining the substrates to be joined using the surface treatment device, comprising an activation step for activating the joining surfaces of the substrates contained in the chamber, a hydroxyl group formation step for forming hydroxyl groups on the joining surfaces of the substrates after the activation step, a stacking step for overlapping and stacking the two substrates having the hydroxyl groups formed on their joining surfaces, and a joining step for heating each of the substrates in the stacked state to join the substrates on their joining surfaces.

[0026] The activation step involves drawing a reactive gas into the container to generate plasma of the reactive gas, and supplying active species generated by the plasma of the reactive gas into the chamber, thereby activating the bonding surface of the substrate.

[0027] The hydroxyl group formation process involves supplying an unsaturated hydrocarbon gas and ozone gas having an ozone concentration of more than 50% by volume to the surfaces to be joined of a substrate contained in the chamber, thereby exposing the surfaces to OH radicals generated by a radical reaction between the unsaturated hydrocarbon gas and the ozone gas, and forming hydroxyl groups on the surfaces to be joined.

[0028] The bonding step is characterized in that the hydroxyl groups are subjected to a dehydration condensation reaction by the heating.

[0029] In addition, in the activation step, the activation depth of the bonded surface of the substrate by the active species generated by the plasma of the reactive gas may be within a range of 1 nm to 100 nm. Effect of the Invention

[0030] As described above, the present invention can contribute to making it easier to make the surface of the substrate hydrophilic as desired by preventing dust and the like from adhering to the surface of the substrate and preventing moisture from remaining on the surface of the substrate. [Brief description of the drawings]

[0031] [Figure 1] A characteristic diagram of ozone gas concentration and OH radical generation efficiency (the ashing rate is normalized to 1 when the ozone concentration is approximately 100 volume %, using the ashing effect of photoresist on a Si wafer as an index). [Diagram 2] FIG. 1 is a schematic configuration diagram for explaining a surface treatment apparatus 1A according to an embodiment (a see-through view of the inside of a chamber 1, etc.). [Diagram 3] FIG. 1 is a schematic configuration diagram for explaining an apparatus 1B according to an embodiment (a see-through view of the inside of a chamber 1, etc.). [Figure 4] FIG. 1 is a schematic configuration diagram for explaining an apparatus 1C according to Verification Example 1 (a see-through view of the inside of a chamber 1, etc.). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] The surface treatment apparatus, substrate bonding apparatus, surface treatment method, and substrate bonding method of the embodiments of the present invention are completely different from configurations in which the surfaces of substrates are simply subjected to plasma treatment or water treatment in a chamber (so-called direct plasma type configurations; hereinafter simply referred to as conventional configurations) as seen in, for example, Patent Documents 1 and 2. That is, the present embodiments are configured to activate a substrate accommodated in a chamber by a so-called remote plasma type, and further to form hydroxyl groups on the activated surface.

[0033] Specifically, it comprises a chamber capable of accommodating a substrate, a plasma generating section having a container (hereinafter simply referred to as a plasma generating container) arranged on the outer periphery of the chamber and capable of drawing in a reactive gas into the plasma generating container to generate plasma of the reactive gas, an unsaturated hydrocarbon gas supply section capable of supplying an unsaturated hydrocarbon gas into the chamber, an ozone gas supply section capable of supplying ozone gas into the chamber, and a gas exhaust section capable of drawing in gas within the chamber and discharging it to the outer periphery of the chamber.

[0034] The plasma generating vessel is characterized in that it is possible to supply active species generated by plasma of a reactive gas (hereinafter simply referred to as plasma-derived active species) into the chamber (that is, the downstream side).

[0035] According to this embodiment, it is possible to prevent damage caused by plasma to the inner wall surface of the chamber and the surface of the substrate (to prevent the generation of minute dust particles, etc.), and it is also possible to prevent moisture, etc. from remaining on the surface of the substrate.

[0036] Furthermore, plasma-derived active species generated in a plasma generating section on the outer periphery of the chamber can be exposed to the surface of the substrate within the chamber, making it possible to increase and activate dangling bonds on the surface.

[0037] In addition, the surface of the substrate in the chamber (the surface activated by the plasma-derived active species) can be exposed to OH radicals generated by the radical reaction between the unsaturated hydrocarbon gas and the ozone gas, and hydroxyl groups can be formed on the surface of the substrate (for example, a molecular layer of hydroxyl groups can be formed). By using a method of forming hydroxyl groups on the surface of the substrate in this way, it is possible to prevent moisture from remaining on the surface of the substrate.

[0038] Therefore, it is easy to make the surface of the substrate hydrophilic as desired. Furthermore, when a plurality of hydrophilic substrates are to be bonded, it is easy to bond the substrates at their bonding surfaces as desired.

[0039] As described above, this embodiment may be configured to activate a substrate accommodated in a chamber by plasma-derived active species using a remote plasma method, and further to form hydroxyl groups on the activated surface. That is, it is possible to appropriately apply technical common knowledge in various fields (e.g., direct bonding field, plasma field, chamber field, ozone gas field, unsaturated hydrocarbon gas field, radical reaction field, surface treatment field, etc.) and appropriately refer to prior art documents, etc. as necessary to modify the design, and examples described below are given as examples. Note that in the examples described below, detailed explanations will be omitted as appropriate, for example, by applying the same reference numerals to overlapping contents.

[0040] <Reference Examples Related to Radical Reactions> For example, Patent Documents 3 and 4 disclose a technique for removing resist adhering to the surface of a substrate (object of surface treatment) by utilizing active species (oxidizing species) such as OH radicals generated by the radical reaction between an unsaturated hydrocarbon gas and ozone gas. This resist removal technique utilizes the properties of ozone, such as the fact that the ozone easily reacts with the carbon double bonds of unsaturated hydrocarbons without the application of thermal energy (heating) or UV irradiation.

[0041] The resist removal technology utilizing the above-mentioned radical reaction is highly effective in removing organic matter such as photoresist, and has been put to practical use, for example, for ashing photoresist and removing organic matter from surfaces without any thermal or plasma damage.

[0042] In the radical reaction, first, the carbon double bond is cleaved by the ozone molecule, and the unstable methylene peroxide generated as a result becomes an intermediate, which further undergoes a fission reaction, generating OH radicals, formic acid, etc. along with carbon dioxide and water. An example of this radical reaction can be shown in the characteristic diagram of ozone gas concentration and OH radical generation efficiency, as shown in Figure 1.

[0043] 1, when the concentration of ozone gas is low (for example, 50% by volume or less), the efficiency of generating OH radicals is also low, and the OH radicals are easily consumed in intermediate reactions. In other words, it can be seen that the number of multi-stage reaction paths in which the generation of OH radicals is amplified decreases, making it difficult to perform the desired surface treatment. On the other hand, when the concentration of ozone gas is high, OH radicals are generated in high concentrations, and a large amount of OH radicals are also likely to be generated in the process of the multi-stage reaction.

[0044] Furthermore, conventional ozone gas generators (e.g., general discharge-type ozonizers) were only able to supply ozone gas at low concentrations (e.g., maximum ozone concentration of about 23 volume %). However, in recent years, devices capable of safely generating ozone gas at high concentrations (e.g., Meidensha's Pure Ozone Generator) have emerged, and various surface treatment technologies that apply radical reactions have begun to be investigated.

[0045] For example, Patent Documents 5 and 6 disclose a technique for modifying the surface of a substrate by oxidizing the surface with OH radicals and forming hydrophilic groups mainly composed of hydroxyl groups (a molecular layer of hydrophilic groups). This modification technique is said to be capable of modifying the surface of the substrate without physically damaging the substrate.

[0046] Specifically, Patent Documents 5 and 6 disclose a method in which an unsaturated hydrocarbon gas and an ozone gas are supplied into a chamber to cause a radical reaction near the surface of a substrate in the chamber, and the surface of the substrate is modified by OH radicals etc. generated by the radical reaction. Also disclosed is a configuration in which an unsaturated hydrocarbon gas and an ozone gas are supplied by a shower head (reference numeral 9 in Patent Document 5, reference numeral 10 or 15 in Patent Document 6) provided at a position facing the substrate in the chamber, so that the surface of the substrate can be efficiently exposed to OH radicals.

[0047] This showerhead has an unsaturated hydrocarbon gas supply passage and an ozone gas supply passage provided inside the showerhead in a mutually separated (non-communicating) state. Also, the surface of the showerhead facing the substrate is provided with a plurality of ejection holes communicating with the unsaturated hydrocarbon gas supply passage and a plurality of ejection holes communicating with the ozone gas supply passage.

[0048] By using such a showerhead, a radical reaction between the unsaturated hydrocarbon gas and the ozone gas can be easily caused near the surface of the substrate in the chamber.

[0049] According to the above-mentioned configuration using the radical reaction, it is possible to form hydroxyl groups on the surface of the substrate (modify the surface with hydroxyl groups) and make the surface hydrophilic, without performing water treatment as in the conventional configuration. It is also possible to prevent moisture from remaining on the surface of the substrate.

[0050] Furthermore, even if energy due to radical reactions (chemical reaction energy) acts within the chamber, it is possible to avoid the action of energy due to plasma processing or the like as in the conventional configuration (energy that may cause plasma damage).

[0051] In addition, when the activity of the substrate surface is low (when there are few dangling bonds), it may be difficult to form a sufficient number of hydroxyl groups on the substrate surface simply by causing a radical reaction between an unsaturated hydrocarbon gas and an ozone gas near the substrate surface, and the substrate may not be rendered hydrophilic as desired.

[0052] On the other hand, in the present embodiment, even if the activity of the substrate surface is low, the substrate surface can be activated by plasma-derived active species using the remote plasma method, and a sufficient number of hydroxyl groups can be easily formed on the activated surface, making it easy to make the substrate hydrophilic as desired.

[0053] Example <Example of surface treatment equipment configuration> An example of the schematic configuration of a surface treatment device 1A according to an embodiment will be described with reference to Fig. 2. This surface treatment device 1A mainly comprises a chamber 1 capable of accommodating a substrate 10, a plasma generation unit 2 having a plasma generation container 21 arranged on the outer periphery of the chamber 1, an unsaturated hydrocarbon gas supply unit 3 capable of supplying an unsaturated hydrocarbon gas into the chamber 1, an ozone gas supply unit 4 capable of supplying an ozone gas into the chamber 1, and a gas exhaust unit 5 capable of sucking in gas from within the chamber 1 and exhausting it to the outer periphery of the chamber 1.

[0054] In the case of the chamber 1 in the figure, a support part 6 capable of supporting a substrate 10 accommodated in the chamber 1 with a support stand 61 is provided. In addition, a shower head 7 is provided on the upper side of the chamber 1 so as to face a surface to be processed (or a surface to be bonded) 11 of the substrate 10 supported by the support part 6.

[0055] The plasma generating unit 2 in the figure is configured to generate inductively coupled plasma. A plasma generating vessel 21 is provided with an intake pipe 22 for drawing reactive gas into the plasma generating vessel 21. The intake pipe 22 is provided with an intake valve 23 capable of adjusting the intake flow rate of reactive gas by opening and closing the intake pipe 22. In addition, a supply pipe 24 capable of supplying gas and the like (gas remaining after plasma generation of reactive gas and plasma-derived active species) in the plasma generating vessel 21 to the chamber 1 is provided on the chamber 1 side (i.e., downstream side) of the plasma generating vessel 21.

[0056] On the outer periphery of the plasma generating vessel 21, there is provided an electrode portion 25 (e.g., an electrode portion extending in a coil shape along the outer periphery of the plasma generating vessel 21) for generating plasma within the plasma generating vessel 21, and a power source 26 capable of applying high-frequency power to the electrode portion 25.

[0057] The unsaturated hydrocarbon gas supply unit 3 includes a supply pipe 31 for supplying the unsaturated hydrocarbon gas, and an intake valve 32 capable of adjusting the supply flow rate of the unsaturated hydrocarbon gas by opening and closing the supply pipe 31, for example.

[0058] In the case of the unsaturated hydrocarbon gas supply unit 3 in the figure, the supply piping 31 is connected to a shower head 7, and the unsaturated hydrocarbon gas can be supplied into the chamber 1 via an unsaturated hydrocarbon gas supply passage (not shown) and a nozzle 73 in the shower head 7.

[0059] The ozone gas supply unit 4 includes a supply pipe 41 for supplying ozone gas, and an intake valve 42 capable of adjusting the supply flow rate of the ozone gas by opening and closing the supply pipe 41, for example.

[0060] In the case of the ozone gas supply unit 4 in the figure, the supply pipe 41 is connected to the shower head 7, and the unsaturated hydrocarbon gas can be supplied into the chamber 1 via the ozone gas supply flow path (a flow path not connected to the unsaturated hydrocarbon gas supply flow path; not shown) in the shower head 7 and the nozzle 74.

[0061] The gas exhaust section 5 includes an exhaust pipe 51 for drawing in gas within the chamber 1 and exhausting it to the outer periphery of the chamber 1, an exhaust valve 52 that can adjust the exhaust flow rate of gas within the chamber 1 by opening and closing the exhaust pipe 51, and a vacuum pump (such as an ozone-resistant dry pump) 53 that generates a suction force to draw in the gas within the chamber 1.

[0062] In the case of such a gas exhaust section 5, for example, the suction force of the vacuum pump 53 can be controlled to maintain a reduced pressure state inside the chamber 1 (a state in which the internal pressure is lower than atmospheric pressure), thereby sucking in gas inside the chamber 1 and exhausting the gas to the outer periphery of the chamber 1.

[0063] Each component of the surface treatment device 1A shown above is configured so as to be appropriately controlled by a control unit not shown in the figure, for example, the plasma generation unit 2, the unsaturated hydrocarbon gas supply unit 3, the ozone gas supply unit 4, and the gas exhaust unit 5 are configured so as to be appropriately controlled.

[0064] For example, in the plasma generating unit 2, the magnitude of the plasma output energy of the reactive gas and the supply flow rate of the plasma-derived active species supplied into the chamber 1 can be appropriately controlled via the intake valve 23, the power source 26, etc. The supply flow rate of the plasma-derived active species can be controlled, for example, by appropriately using a flowmeter or the like in the plasma generating vessel 21, or the pressure can be controlled by appropriately using a pressure gauge or the like.

[0065] As a specific example, the supply flow rate of plasma-derived active species may be controlled so that the surface 11 to be treated can be activated to a desired activation depth (for example, an activation depth measurable by FT-IR, XPS, etc.) in the activation step S1 described below depending on the type of substrate 1 to be treated and the state of the surface 11 to be treated (such as the surface roughness and the thickness of the natural oxide film). More specifically, the activation depth of the surface 11 to be treated by the plasma-derived active species may be controlled to be about several nm to several hundred nm (for example, about 1 nm to 100 nm).

[0066] By activating the treatment surface 11 in this manner, it becomes easier to achieve the desired hydrophilicity in the hydroxyl group formation step S2 described below, and it also becomes possible to bond as desired through the lamination step S3 and bonding step S4 described below.

[0067] In the unsaturated hydrocarbon gas supply unit 3, the supply flow rate of the unsaturated hydrocarbon gas is controlled so as to be appropriately set via an intake valve 32 or the like, and in the ozone gas supply unit 4, the supply flow rate of the ozone gas is controlled so as to be appropriately set via an intake valve 42 or the like.

[0068] In the gas exhaust unit 5, the exhaust flow rate of the gas in the chamber 1 and the reduced pressure state in the chamber 1 are controlled via an exhaust valve 52, a vacuum pump 53, and the like.

[0069] The reduced pressure state in the chamber 1 can be appropriately adjusted within a range in which the desired hydrophilization of the treatment surface 11 of the substrate 10 can be achieved, for example, while each gas is being supplied from the plasma generating unit 2, the unsaturated hydrocarbon gas supplying unit 3, and the ozone gas supplying unit 4. For example, the reduced pressure state in the chamber 1 can be adjusted by appropriately controlling the aperture of the exhaust valve 52 and appropriately operating the vacuum pump 53.

[0070] As a specific example, while the gas (gas containing plasma-derived active species) is being supplied from the plasma generating unit 2, the inside of the chamber 1 is kept at 10 -2 The pressure can be reduced to a few Pa to a few hundred Pa (for example, about 0.01 Pa to 100 Pa).

[0071] While each gas is being supplied from the unsaturated hydrocarbon gas supply unit 3 and the ozone gas supply unit 4, the pressure can be reduced to several thousand Pa or less (e.g., about 1000 Pa or less), preferably several hundred Pa or less, and more preferably several tens of Pa or less (e.g., about 50 Pa or less).

[0072] <An example of hydrophilizing the substrate 10 by the surface treatment device 1A> When the treatment surface 11 of the substrate 10 is made hydrophilic by the surface treatment device 1A, for example, the activation step S1 and the hydroxyl group formation step S2 are carried out in this order as described below.

[0073] First, in the activation step S1, while a reactive gas is being sucked into the plasma generating vessel 21, high frequency power from the power source 26 is applied to the electrode portion 25 to generate plasma of the reactive gas in the plasma generating vessel 21, thereby generating plasma-derived active species. Then, the plasma-derived active species generated as described above are supplied into the chamber 1, thereby exposing the treatment surface 11 of the substrate 10 to the plasma-derived active species and activating it.

[0074] Next, in the hydroxyl group formation step S2, an unsaturated hydrocarbon gas from the unsaturated hydrocarbon gas supply unit 3 and ozone gas from the ozone gas supply unit 4 are supplied to the processing surface 11 of the substrate 10 in the chamber 1. As a result, a radical reaction between the unsaturated hydrocarbon gas and the ozone gas occurs near the processing surface 11 of the substrate 10, and the OH radicals generated by the radical reaction are exposed to the processing surface 11, forming hydroxyl groups on the processing surface 11.

[0075] <An example of bonding of a hydrophilized substrate 10> When a substrate 10 is to be bonded, the treated surface 11, which has been made hydrophilic by carrying out the activation step S1 and the hydroxyl group formation step S2 described above, is used as the bonding surface, and bonding can be carried out, for example, by carrying out the lamination step S3 and bonding step S4 in that order as shown below.

[0076] First, in the lamination step S3, two substrates 10 having hydroxyl groups formed thereon through the activation step S1 and the hydroxyl group formation step S2 are stacked and laminated (temporarily bonded) on the treatment surface 11. It is preferable that the substrates 10 in this laminated state are pressed against each other on the treatment surface 11 (for example, pressed at 1 MPa or more) to ensure sufficient adhesion.

[0077] In the bonding step S4, the substrates 10 that have been laminated in the lamination step S3 are heated to cause a dehydration condensation reaction of the hydroxyl groups. As a result, the substrates 10 are bonded to each other at their treatment surfaces 11.

[0078] <One example of the support structure of the base 10> The activation step S1, the hydroxyl group forming step S2, the lamination step S3, and the bonding step S4 (hereinafter collectively referred to simply as steps S1 to S4) may be performed while the substrate 10 is appropriately supported by a support part 6, but the support structure of the support part 6 is not particularly limited. For example, the chamber 1 may be configured to support a plurality of substrates 10, which allows each of the steps S1 to S4 to be performed simultaneously on each of the substrates 10.

[0079] Also, for example, like an apparatus 1B shown in FIG. 3, a plurality of substrates 10 housed in a chamber 1 may be supported movably, or each substrate 10 may be pressurized or heated.

[0080] 3, the apparatus 1B includes a support unit 6B capable of supporting two substrates 10a, 10b in the chamber 1. The support unit 6B includes a pair of support stages 61a, 61b that support the two substrates 10a, 10b, respectively, and are arranged facing each other, a pair of support arms 62a, 62b that support the outer peripheries of the support stages 61a, 61b so that the support stages 61a, 61b can move toward and away from each other in the facing direction (hereinafter simply referred to as the facing direction), and a rotation shaft 63 that supports the support arms 62a, 62b rotatably along the facing direction.

[0081] The support unit 6B thus configured can rotate the support arms 62a, 62b about the rotation shaft 63 by, for example, an operating unit (not shown) on the outer periphery of the chamber 1, and can move the support bases 61a, 61b toward and away from each other in the opposing directions. The support bases 61a, 61b are also provided with heating units (not shown) capable of heating the substrates 10a, 10b supported by the support bases 61a, 61b, respectively.

[0082] In the apparatus 1B, the substrates 10a and 10b are used as the objects to be joined, and steps S1 to S4 can be appropriately performed. First, when performing the activation step S1, as shown in FIG. 3, the two substrates 10a and 10b are supported on the support stages 61a and 61b so that the surfaces to be treated (surfaces to be joined) 11, which are the side surfaces of one end of each substrate, are positioned apart from each other in an opposing posture. Then, in this supported state (hereinafter simply referred to as the substrate supported state), while a reactive gas is sucked into the plasma generating vessel 21, high-frequency power from the power source 26 is applied to the electrode unit 25 to generate plasma of the reactive gas in the plasma generating vessel 21, thereby generating plasma-derived active species. Then, the plasma-derived active species generated as described above are supplied into the chamber 1, and the surfaces to be treated 11 of the substrates 10a and 10b are exposed to the plasma-derived active species and activated.

[0083] Next, when the hydroxyl group forming step S2 is performed, in the substrate supported state, an unsaturated hydrocarbon gas and an ozone gas are respectively supplied from the unsaturated hydrocarbon gas supply unit 3 and the ozone gas supply unit 4. As a result, a radical reaction occurs near the processing surface 11 of each of the substrates 10a and 10b, and hydroxyl groups are formed on the processing surface 11.

[0084] Thereafter, in the lamination step S3, the support part 6B is operated to move the support bases 61a, 61b closer to each other in the opposing direction, so that the treatment surfaces 11 of the substrates 10a, 10b are overlapped and laminated and pressed against each other. Then, in the bonding step S4, the substrates 10a, 10b in the laminated (pressure-bonded) state are heated by the heating part, causing a dehydration condensation reaction of hydroxyl groups, and the substrates 10a, 10b are bonded at their treatment surfaces 11.

[0085] Therefore, with the above-described apparatus 1B, steps S1 to S4 of the substrates 10a and 10b can be performed in-situ in the same chamber 1. That is, the apparatus 1B not only hydrophilizes the treatment surfaces 11 of the substrates 10a and 10b, but can also be used as an apparatus for bonding the substrates 10a and 10b (substrate bonding apparatus).

[0086] For example, in the case of the surface treatment apparatus 1A, after performing the activation step S1 and the hydroxyl group forming step S2 in the chamber 1, the substrate 10 is removed from the chamber 1 and the lamination step S3 and the bonding step S4 are performed, but in this case, it is considered that not a small amount of moisture may remain on the treated surface 11 of the substrate 10. On the other hand, according to the apparatus 1B, since the steps S1 to S4 can be performed in-situ as described above, it is easier to prevent moisture from remaining on the treated surface 11.

[0087] <Examples of reactive gases, unsaturated hydrocarbon gases, and ozone gas> The reactive gas may be any gas capable of generating plasma of the reactive gas in the activation step S1, thereby generating plasma-derived active species to activate the treatment surface 11 of the substrate 10, and various modes are applicable. Specific examples of the reactive gas include gases containing components such as oxygen, argon, and nitrogen, and also include mixed gases containing a plurality of such components.

[0088] The unsaturated hydrocarbon gas and the ozone gas may be any gas that can cause a radical reaction in the hydroxyl group forming step S2 to form hydroxyl groups on the surface 11 to be treated, and various modes are applicable.

[0089] Specific examples of unsaturated hydrocarbon gases include ethylene, propylene, acetylene, butadiene, benzene, toluene, o-xylene, styrene, α-butylene, etc. Specific examples of ozone gas include ozone gas with an ozone concentration of more than 50% by volume, and more preferably, ozone gas with a high concentration (e.g., 80% by volume or more, or 90% by volume or more).

[0090] <An example of the base 10> The substrate 10 can be one that can activate the treated surface 11 through an activation step S1 and a hydroxyl group formation step S2 to form hydroxyl groups, and when the substrate 10 is to be bonded, it is possible to use one that can be bonded through the activation step S1 and the hydroxyl group formation step S2, followed by a lamination step S3 and a bonding step S4. Although not particularly limited, if necessary, the treated surface 11 can be planarized in advance (for example, planarized by CMP or the like so as to have a surface roughness that is sufficiently small at the atomic level).

[0091] Furthermore, since the hydroxyl group formation process S2 and the bonding process S4 can each be performed at a relatively low temperature, for example, when the base 10 is a substrate or a film, it is not limited to a substrate having relatively high heat resistance such as a silicon substrate, and may be a substrate formed of a synthetic resin having relatively low heat resistance.

[0092] Examples include various substrates used in MEMS, semiconductors, FPDs, etc., such as silicon substrates, glass substrates, GaN substrates, SiC substrates, diamond substrates, etc., as well as metal substrates, film-like substrates, and substrates provided with a silicon oxide film (SiO2 film). Substrates of the same or different types may be selected and used.

[0093] When the base 10 is made of a resin, examples of the resin include polyester resin, aramid resin, olefin resin, polypropylene, PPS (polyphenylene sulfide), PET (polyethylene terephthalate), and the like.

[0094] Other examples include those made from PE (polyethylene), PEN (polyethylene naphthalate), POM (polyoxymethylene or acetal resin), PEEK (polyether ether ketone), ABS resin (acrylonitrile, butadiene, styrene copolymer synthetic resin), PA (polyamide), PFA (tetrafluoroethylene, perfluoroalkoxyethylene copolymer), PI (polyimide), PVD (polyvinyl dichloride), acrylic resin, etc.

[0095] <Verification example 1> After the surface treatment device 1A was applied under any of the conditions (1) to (4) described below to hydrophilize the substrate 10, the water contact angle (°) of the treated surface 11 of the substrate 10 was observed, and the results are shown in Table 1 described below.

[0096] The substrate 10 was a silicon wafer having a thermal oxide film formed on one end surface thereof, and the surface of the thermal oxide film (a surface having a water contact angle of 54° before hydrophilization) was used as the treated surface 11. The activation step S1 was performed using nitrogen gas as the reactive gas, with the output energy of the plasma of the reactive gas set to 150 W, the pressure in the plasma generating vessel 21 set to 200 Pa, the pressure in the chamber 1 (treatment pressure) set to 10 Pa, and the treatment time set to 8 minutes.

[0097] The hydroxyl group formation process S2 was carried out by applying an unsaturated hydrocarbon gas, ethylene gas as ozone gas, and high-concentration ozone gas (ozone concentration of 80% by volume or more), with the supply flow rate of the unsaturated hydrocarbon gas set to 40 sccm, the supply flow rate of the ozone gas set to 200 sccm, the pressure in chamber 1 (processing pressure) set to 40 Pa, and the processing time set to 1 minute.

[0098] Condition (1): Only the activation step S1 is carried out to make the substrate hydrophilic (the hydroxyl group formation step S2 is omitted). Condition (2): Hydrophilization is performed by carrying out only the hydroxyl group formation step S2 (the activation step S1 is omitted). Condition (3): Hydrophilization is achieved by carrying out both the activation step S1 and the hydroxyl group formation step S2. Condition (4): After the activation step S1, a conventional water treatment is carried out to make the material hydrophilic (the hydroxyl group formation step S2 is omitted).

[0099] [Table 1]

[0100] As shown in Table 1, the treated surface 11 of the substrate 10 that was hydrophilized under condition (1) had a small water contact angle compared to the surface that was hydrophilized under condition (2). In the case of condition (1), it is believed that the activation step S1 caused the formation of dangling bonds and surface nitridation on the treated surface 11, which reacted with moisture in the air to make the surface hydrophilic. In the case of condition (2), although the OH radicals in the hydroxyl group formation step S2 caused some modification of dangling bonds that were presumably present on the treated surface 11 with hydroxyl groups and removal of organic contamination, it is believed that the hydrophilization was insufficient compared to the case of condition (1).

[0101] On the other hand, in the case of condition (3), the treated surface 11 activated by the activation step S1 (the treated surface 11 with dangling bonds generated by the activation step S1 and surface nitridation) is modified with hydroxyl groups by OH radicals in the hydroxyl group formation step S2, and it is considered that sufficient hydrophilization is achieved without using moisture in the air.

[0102] <Verification example 2> Next, two substrates 10 that have been hydrophilized according to any one of the conditions (1) to (4) are prepared for each of the conditions (1) to (4), and the two substrates 10 are bonded through a lamination step S3 and a bonding step S4 to measure the bonding strength (J / m 2 ) were observed, and the results are shown in Table 2.

[0103] [Table 2]

[0104] As shown in Table 2, the highest bonding strength was obtained in the substrate 10 hydrophilized under condition (3) compared to the substrates hydrophilized under conditions (1), (2), and (4). In the case of condition (3), it is believed that the hydroxyl group modification by OH radicals in the hydroxyl group formation step S2 was effectively performed on the treated surface 11 activated by the activation step S1. In addition, in the case of condition (4), it is believed that excess moisture remained on the treated surface 11 due to the water treatment after the activation step S1, inhibiting bonding at the treated surface 11 and resulting in a low bonding strength.

[0105] <Verification example 3> Next, in the conventional apparatus 1C shown in FIG. 4, the substrate 10 was hydrophilized in the same manner as in Verification Example 1 by applying any one of the conditions (5) to (8) described below, and then the bonding strength (J / m 2 ) were observed, and the results are shown in Table 3 below.

[0106] The apparatus 1C in FIG. 4 has the same configuration as the surface treatment apparatus 1A, but in place of the plasma generating unit 2, a plasma generating unit 2C of a direct plasma type is used.

[0107] In this plasma generating section 2C, an intake pipe 22 for intake of a reactive gas is connected to a shower head 7, and the reactive gas can be supplied into the chamber 1 via a reactive gas supply flow path (a flow path not connected to the unsaturated hydrocarbon gas supply flow path and the ozone gas supply flow path; not shown) in the shower head 7 and an ejection port 75. In addition, the support table 61 is used as an electrode, and high frequency power from a power source 26 can be applied to both the support table 61 and the shower head 7.

[0108] In the apparatus 1C, an activation step S11, which will be described later, was first performed, followed by a hydroxyl group forming step S2, a lamination step S3, and a bonding step S4 in that order. In this activation step S11, high-frequency power from the power source 26 was applied to both the support stand 61 and the shower head 7 while a reactive gas was supplied into the chamber 1. This generated plasma of the reactive gas in the chamber 1, which generated plasma-derived active species that were exposed to the treatment surface 11 of the substrate 10 for activation.

[0109] The activation step S11 was performed by using nitrogen gas as the reactive gas, setting the output energy of the plasma of the reactive gas to 375 W, the pressure in the chamber 1 (processing pressure) to 500 Pa, and the processing time to 30 seconds.

[0110] Condition (5): Only the activation step S11 is carried out to make the substrate hydrophilic (the hydroxyl group formation step S2 is omitted). Condition (6): Hydrophilization is performed by carrying out only the hydroxyl group formation step S2 (the activation step S11 is omitted). Condition (7): Hydrophilization is achieved by carrying out both the activation step S11 and the hydroxyl group formation step S2. Condition (8): After the activation step S11, a conventional water treatment is carried out to make the material hydrophilic (the hydroxyl group formation step S2 is omitted).

[0111] [Table 3]

[0112] As shown in Table 3, the substrate 10 hydrophilized under conditions (5) to (8) tended to have lower bonding strength than the substrate 10 hydrophilized under conditions (1) to (4). In the cases of conditions (5) to (8), it is believed that ions and the like from the plasma generated in the activation step S11 collide (etch, etc.) with the inner wall surface of the chamber 1, the shower head 7, etc., generating minute dust particles and the like within the chamber 1, which then adhere to the treatment surface 11 of the substrate 10, thereby inhibiting the desired bonding.

[0113] In the case of condition (8), it is possible that dust and the like adhering to the treated surface 11 of the substrate 10 was removed by the water treatment. However, it is considered that the water treatment left excess moisture on the treated surface 11, inhibiting bonding at the treated surface 11 and reducing the bonding strength.

[0114] Although the present invention has been described in detail above only with respect to the specific examples, it will be apparent to those skilled in the art that various modifications are possible within the scope of the technical concept of the present invention, and it is natural that such modifications fall within the scope of the claims. [Explanation of symbols]

[0115] 10(10a,10b)...Base 11...Surface to be treated (surface to be joined) 1. Chamber 2. Plasma generating section 3...Unsaturated hydrocarbon gas supply section 4…Ozone gas supply unit 5...Gas exhaust section 6...Support part

Claims

1. a chamber capable of accommodating a substrate; a plasma generating unit having a container disposed on the outer periphery of the chamber and capable of drawing a reactive gas into the container and generating plasma of the reactive gas; an unsaturated hydrocarbon gas supply unit capable of supplying an unsaturated hydrocarbon gas into the chamber; an ozone gas supply unit capable of supplying ozone gas into the chamber; a gas exhaust section capable of sucking gas from within the chamber and discharging it to an outer periphery of the chamber; Equipped with The surface treatment apparatus according to claim 1, wherein the container is capable of supplying activated species generated by plasma of the reactive gas into the chamber.

2. 2. The surface treatment apparatus according to claim 1, wherein said reactive gas contains at least one of oxygen, argon, and nitrogen.

3. 2. The surface treatment apparatus according to claim 1, wherein the plasma of the reactive gas is an inductively coupled plasma.

4. the chamber is provided with a shower head at a position facing the substrate accommodated in the chamber, The shower head comprises: a supply flow path for the unsaturated hydrocarbon gas by the unsaturated hydrocarbon gas supply unit; a supply flow path of the ozone gas by the ozone gas supply unit; 2. The surface treatment apparatus according to claim 1, further comprising:

5. output energy of the plasma of the reactive gas in the plasma generating unit; a supply flow rate of the unsaturated hydrocarbon gas in the unsaturated hydrocarbon gas supply unit; and a supply flow rate of the ozone gas in the ozone gas supply unit; and a flow rate of gas discharged from the chamber by the gas discharge unit and a pressure in the chamber; 2. The surface treatment apparatus according to claim 1, further comprising a control unit capable of controlling the above.

6. The control unit is The output energy of the plasma of the reactive gas can be controlled to be set within a range of 50 W to 200 W; In a state in which the plasma of the reactive gas is generated, the pressure in the chamber can be controlled to be set within a range of 0.01 Pa to 100 Pa. The surface treatment device according to claim 5 .

7. 6. The surface treatment apparatus according to claim 5, wherein the control unit is capable of controlling the pressure in the chamber to be set to 1000 Pa or less in a state in which the unsaturated hydrocarbon gas and the ozone gas are supplied into the chamber.

8. A surface treatment apparatus according to any one of claims 1 to 7, the chamber includes a support portion that supports the two substrates as objects to be joined within the chamber, The substrate joining apparatus is characterized in that the support section supports the substrates with their surfaces to be joined facing each other and is movable toward and away from each other in the opposing direction.

9. A method using the surface treatment device according to any one of claims 1 to 7, an activation step of activating a surface of the substrate accommodated in the chamber; a hydroxyl group forming step of forming hydroxyl groups on the surface of the substrate after the activation step; having The activation step includes sucking a reactive gas into the container to generate plasma of the reactive gas, and supplying active species generated by the plasma of the reactive gas into the chamber to activate the surface of the substrate; The hydroxyl group formation process is a surface treatment method characterized in that the unsaturated hydrocarbon gas and the ozone gas having an ozone concentration of more than 50 volume % are supplied to the surface of the substrate contained in the chamber, thereby exposing the surface of the substrate to OH radicals generated by a radical reaction between the unsaturated hydrocarbon gas and the ozone gas, thereby forming hydroxyl groups on the surface of the substrate.

10. 10. The surface treatment method according to claim 9, wherein in the activation step, the activation depth of the surface of the substrate by the active species generated by the plasma of the reactive gas is within a range of 1 nm to 100 nm.

11. A method for bonding a substrate to be bonded, using the surface treatment apparatus according to any one of claims 1 to 7, comprising the steps of: an activation step of activating a surface to be joined of the substrate accommodated in the chamber; a hydroxyl group forming step of forming hydroxyl groups on the surface to be joined of the substrate after the activation step; a lamination step of overlapping and laminating the two substrates having the hydroxyl groups formed thereon at their joining surfaces; a bonding step of heating each of the laminated substrates to bond the substrates at their bonding surfaces; having The activation step includes sucking a reactive gas into the container to generate plasma of the reactive gas, and supplying active species generated by the plasma of the reactive gas into the chamber to activate the bonded surface of the substrate; The hydroxyl group forming step includes supplying an unsaturated hydrocarbon gas and an ozone gas having an ozone concentration of more than 50% by volume to a surface to be joined of a substrate accommodated in the chamber, thereby exposing the surface to OH radicals generated by a radical reaction between the unsaturated hydrocarbon gas and the ozone gas, thereby forming hydroxyl groups on the surface to be joined; The method for bonding substrates, wherein the bonding step causes a dehydration condensation reaction of the hydroxyl groups by heating.

12. 12. The method for bonding substrates according to claim 11, wherein in said activation step, the activation depth of the bonded surfaces of said substrates by the active species generated by the plasma of said reactive gas is within a range of 1 nm to 100 nm.

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