Bonding method

Abstract

The invention provides a bonding method including a lamination step and a bonding treatment step. In the laminating step, the first joining object and the second joining object are laminated such that the heat absorbing layer and the joining material layer are sandwiched between the joining surfaces of the first joining object and the second joining object. In the bonding process step, the bonding material layer is heated by the heat absorbed by the heat absorbing layer from the laser light by irradiating the heat absorbing layer with the laser light, thereby bonding the first bonding object and the second bonding object by the bonding material layer.

Description

Technical Field

[0001] The present invention relates to a joining technology using a laser. Background Art

[0002] As one of the manufacturing technologies for semiconductor devices (MEMS, etc.), there is a technology for bonding two wafers using the eutectic reaction of two metals. In this technology, a metal layer containing one of the two metals that produce the eutectic reaction as a main component and a metal layer containing the other metal as a main component are formed on the bonding surfaces of the two wafers. In addition, as a combination of two metals that produce the eutectic reaction, for example, a combination of aluminum (Al) and germanium (Ge) can be used. Moreover, by generating a eutectic reaction at the contact portion of their metal layers, the two wafers can be bonded.

[0003] This bonding technology is used, for example, to seal sensors (gyro sensors, biosensors, etc.) and waveguides within devices. Furthermore, to induce the aforementioned eutectic reaction, the contact area between the two metal layers must be heated to a temperature that allows the reaction to occur. To achieve this, two wafers are clamped and pressed together, bringing the two metal layers into contact. The sensor, etc., to be sealed, is then heated along with the two wafers (see, for example, Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 11-220141

[0007] Patent Document 2: Chinese Utility Model No. 210223961 Summary of the Invention

[0008] Technical problem to be solved by the invention

[0009] However, in the above-mentioned previous bonding technology, because the sensor to be sealed is also heated, there is a problem of damage due to heat. Therefore, the sensors that can be sealed in the device are limited to those with high heat resistance. In addition, the temperature of the bonding area (to the temperature at which the eutectic reaction occurs) takes a long time. Moreover, after bonding, the thermal stress of the wafer needs to be gradually relaxed, so cooling down also takes a long time. Therefore, there is a problem that the time required for a single bonding process is long.

[0010] Another problem is that when the two metals have different linear expansion coefficients, deformation may occur at the junction of the two metal layers during heating and cooling. Therefore, in order to prevent such deformation, the conventional joining technology mentioned above requires selecting metals with similar linear expansion coefficients, which significantly limits the freedom of choice.

[0011] Therefore, in recent years, a technique has been proposed for locally heating the contact area between two metal layers using a laser (see Patent Document 2). Specifically, two wafers are clamped and pressed between a quartz plate that allows the laser to pass through and other components (such as a suction cup). In this state, the contact area between the two metal layers is irradiated with laser light through the quartz plate.

[0012] This laser bonding technology reduces the thermal impact on the sensor by locally heating the contact area between the two metal layers. This allows even sensors with low heat resistance to be sealed within the device. Furthermore, because laser light can be used to focus heating at the junction of the two metal layers, the temperature of the junction can be rapidly raised to a temperature that triggers a eutectic reaction, shortening the bonding process time.

[0013] Furthermore, even if the two metals have different linear expansion coefficients and deformation occurs during heating or cooling, the deformation occurs only in the local area irradiated by the laser and is therefore significantly small. As a result, the deformation has a significantly smaller impact on the joining portion of the two metal layers. Therefore, when selecting the two metals, metals with different linear expansion coefficients can be selected, increasing the degree of freedom in selection.

[0014] On the other hand, metals that produce eutectic reactions often have high light reflectivity and transmittance, making them less effective at absorbing laser light. Germanium (Ge) is a particularly good metal for absorbing laser light, but with a reflectivity of approximately 35% and a transmittance of approximately 30%, it can only absorb about 35% of the laser light it receives. Consequently, laser-induced eutectic reactions present challenges in efficiently heating the target metal layer, and the reflected or transmitted laser light can adversely affect sensors and other devices.

[0015] Therefore, an object of the present invention is to enable efficient use of laser light in a joining technique using laser light.

[0016] Technical means for solving technical problems

[0017] The first joining method of the present invention includes a lamination step and a joining treatment step. In the lamination step, a first joining target and a second joining target are overlapped so that a heat-absorbing layer and a joining material layer are sandwiched between their joining surfaces. In the joining treatment step, the heat-absorbing layer is irradiated with laser light. Heat absorbed by the heat-absorbing layer from the laser light heats the joining material layer, thereby joining the first joining target and the second joining target via the joining material layer.

[0018] According to the first bonding method, even when the bonding material layer contains a material that does not easily absorb laser light as a main component and thus it is difficult to efficiently heat the bonding material layer by irradiating the bonding material layer with laser light, by irradiating the heat absorbing layer with laser light, the heat absorbing layer can be efficiently absorbed by the heat absorbing layer, thereby indirectly heating the bonding material layer through the heat absorbing layer.

[0019] The second joining method of the present invention is a method for joining a first joining object and a second joining object using a laser, and includes a joining material layer forming process, a lamination process and a joining treatment process. In the joining material layer forming process, a joining material layer is formed along at least one of the joining surface of the first joining object and the joining surface of the second joining object, and the joining material layer contains at least one of titanium (Ti), chromium (Cr) and their oxides as a main component. In the lamination process, the first joining object and the second joining object are overlapped in such a manner that a joining material layer is sandwiched between the joining surfaces of the first joining object and the second joining object. In the joining treatment process, the joining material layer is heated by irradiating the joining material layer with a laser, thereby joining the first joining object and the second joining object using the joining material layer.

[0020] According to the second joining method, by irradiating the joining material layer with laser light, the joining material layer can efficiently absorb the laser light, thereby joining the joining surfaces of two objects to be joined.

[0021] Effects of the Invention

[0022] According to the present invention, laser light can be effectively used in a bonding technique using laser light. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a conceptual diagram showing an example of a bonding apparatus that can be used in the bonding method of the present invention.

[0024] Figure 2 This is a conceptual diagram illustrating the objects to be joined in the first embodiment.

[0025] Figure 3 (A) is a cross-sectional view showing an example of the pattern shape of the metal layer, Figure 3 (B) is a plan view showing this example.

[0026] Figure 4 This is a flowchart showing the bonding method according to the first embodiment.

[0027] Figure 5 This is a conceptual diagram illustrating the objects to be joined in the second embodiment. DETAILED DESCRIPTION

[0028] [1]Jointing device

[0029] Figure 1 : is a conceptual diagram showing a bonding device that can be used in the bonding method of the present invention. Figure 1 As shown, the bonding apparatus is an apparatus for bonding two bonding objects 101 and 102, and includes a chamber mechanism 1, a pressurizing mechanism 2, a laser light source 3, and a control unit 4. The configuration of each component will be described in detail below.

[0030] <Cavity Mechanism 1>

[0031] The chamber mechanism 1 includes a first chamber configuration section 11 , a second chamber configuration section 12 , a drive section 13 , and an exhaust section 14 .

[0032] The first chamber component 11 and the second chamber component 12 constitute a sealed space (hereinafter referred to as "chamber 10") for performing the bonding process. They are configured to selectively open and close the chamber 10 by moving them relatively close to each other in the vertical direction. A more specific structure is described below.

[0033] The first chamber forming part 11 is composed of a first cylindrical portion 111 and a stage 112 supported on the inner side of the first cylindrical portion 111 without a gap therebetween. The first cylindrical portion 111 is arranged in a state where the direction of its central axis is consistent with the vertical direction, and the stage 112 is supported by the first cylindrical portion 111 to be horizontal. Here, the stage 112 is a stage having a transparency that allows laser light to pass through, and is formed of, for example, quartz. In addition, the two joining objects 101 and 102 are placed on the stage 112 in a state where their joining surfaces 101a and 102a are opposite to each other. In addition, in Figure 1 In the example of FIG. 1 , the objects 101 and 102 to be joined are placed on the stage 112 with the object 101 on top.

[0034] The second chamber forming portion 12 is composed of a second cylindrical portion 121 disposed coaxially with the first cylindrical portion 111 above the first cylindrical portion 111, and a top plate 122 that closes the upper end of the second cylindrical portion 121. Furthermore, by bringing the upper end of the first cylindrical portion 111 and the lower end of the second cylindrical portion 121 into contact with each other without a gap, the chamber 10 can be formed between the stage 112 and the top plate 122.

[0035] The driving unit 13 moves at least one of the first chamber configuring unit 11 and the second chamber configuring unit 12 in the vertical direction to bring the components closer to each other.

[0036] The exhaust unit 14 is a portion that reduces the internal pressure of the chamber 10 until the chamber 10 (specifically, the space between the diaphragm 21 and the stage 112 in the chamber 10, which will be described later) reaches a vacuum state. A pressure regulating device such as a vacuum pump is used in the exhaust unit 14. Furthermore, the chamber mechanism 1 may further include a gas supply unit that supplies processing gas (such as argon (Ar) gas) into the chamber 10.

[0037] <Pressure mechanism 2>

[0038] The pressurizing mechanism 2 applies pressure to the bonding objects 101 and 102 from the side opposite to the stage 112. In this embodiment, the pressurizing mechanism 2 comprises a diaphragm 21 and a drive unit 22 for actuating the diaphragm 21. It applies pressure to the back surface 101b of the bonding object 101, which is located on the side opposite to the stage 112, of the two bonding objects 101 and 102. A more specific structure is described below.

[0039] The diaphragm 21 is supported inside the second cylindrical portion 121 with no gap therebetween so as to be in contact with the back surface 101 b of the bonding target 101 when the cavity 10 is formed.

[0040] The driving unit 22 actuates the diaphragm 21 by transmitting pressure to the diaphragm 21 using the transmission medium 221. More specifically, the transmission medium 221 is filled between the diaphragm 21 and the top plate 122 within the second chamber forming portion 12. The driving unit 22 actuates the diaphragm 21 via the transmission medium 221 by varying the pressure applied to the transmission medium 221. The transmission medium 221 may be either a liquid or a gas.

[0041] Laser Light Source 3

[0042] The laser light source 3 is a component that emits laser light and is located below the stage 112, which has a translucent property that allows the laser light to pass through. Furthermore, the laser light source 3 can irradiate the joining objects 101 and 102 on the stage 112 with laser light while scanning the laser light in a horizontal plane along the pattern of an intervening layer, such as the metal layer 201 (described later). Furthermore, the laser light source 3 can focus the laser light on the joining portion between the joining objects 101 and 102.

[0043] <Control Unit 4>

[0044] The control unit 4 is composed of a processing device such as a CPU (Central Processing Unit) or a microcomputer, and controls the various operating units of the bonding apparatus (such as the chamber mechanism 1, the pressurizing mechanism 2, and the laser light source 3).

[0045] During the bonding process, the control unit 4 brings the first chamber component 11 and the second chamber component 12 closer together, integrating them into a single unit, with the two bonding objects 101 and 102 placed on the stage 112, thereby forming the chamber 10. Furthermore, the control unit 4 controls the exhaust unit 14 to reduce the internal pressure of the chamber 10 until the chamber 10 (specifically, the space between the diaphragm 21 and the stage 112 in the chamber 10) reaches a vacuum state. Furthermore, the control unit 4 supplies processing gas (such as argon (Ar) gas) into the chamber 10 as needed.

[0046] Thereafter, the control unit 4 controls the pressurizing mechanism 2 to apply pressure to the back surface 101 b of the bonding object 101 via the diaphragm 21 .

[0047] Here, the diaphragm 21 can flexibly change in accordance with the shape of the back surface 101b of the joining object 101 when pressure is applied to the back surface 101b of the joining object 101, thereby being able to apply uniform pressure to the back surface 101b in close contact with the back surface 101b of the joining object 101, and can use this pressure to deform the joining object 101 (including elastic deformation). In addition, the diaphragm 21 can continuously apply uniform pressure to the back surface 101b by following the shape changes of the back surface 101b of the joining object 101 that occur as the joining object 101 deforms. Therefore, by applying uniform pressure to the back surface 101b of the joining object 101 using the diaphragm 21, even if the pressure is relatively small, it is possible to deform the joining object 101 while maintaining this state in such a manner that the intervening layer (metal layer 201, etc.) is sandwiched between the two joining objects 101 and 102 without a gap. Furthermore, by reducing the pressure required for bonding, the required strength of the stage 112 (the strength required to withstand the pressure during bonding) is also reduced accordingly, and as a result, the thickness of the stage 112 can be made relatively small.

[0048] After applying pressure to the back surface 101b of the joining object 101 via the pressurizing mechanism 2, the control unit 4 maintains this pressure while controlling the laser light source 3 to irradiate the joining portion of the joining objects 101 and 102 with laser light through the stage 112. Furthermore, the control unit 4 scans the laser light in a horizontal plane along the pattern of the intervening layer (metal layer 201, etc.). This allows the joining surfaces 101a and 102a of the two joining objects 101 and 102 to be joined together over the entire area of ​​the joining objects 101 and 102.

[0049] Furthermore, in the above-described bonding apparatus, the diaphragm 21 may have a structure having an adsorption surface that adsorbs the back surface 101b of the bonding object 101 (i.e., a structure having the function of adsorbing the bonding object 101). Furthermore, the bonding apparatus may further include a positioning mechanism that adjusts the positional relationship between the bonding object 101 held (adsorbed) by the diaphragm 21 and the bonding object 102 placed on the stage 112. As an example, the positioning mechanism can adjust the positional relationship between the bonding object 101 held (adsorbed) by the diaphragm 21 and the bonding object 102 placed on the stage 112 by adjusting the position of at least one of the first chamber component 11 and the second chamber component 12 within a horizontal plane.

[0050] In the above-described bonding apparatus, the pressurizing mechanism 2 is not limited to being composed of the diaphragm 21, and may be appropriately modified to include another mechanism capable of applying pressure to the back surface 101b of the bonding object 101. Furthermore, the positional relationship between the stage 112 and the pressurizing mechanism 2 (diaphragm 21) may be appropriately modified to be vertically reversed, and the positions of other components (such as the laser light source 3) may also be appropriately modified accordingly.

[0051] In the above-described bonding apparatus, when the bonding target 102 is placed on the stage 112, the bonding target 102 comes into surface contact with the mounting surface of the stage 112 (the surface on which the bonding target 102 is placed). Furthermore, when the bonding target 102 is primarily composed of a material having a different refractive index from that of the material constituting the stage 112 (for example, when the stage 112 is a quartz plate and the bonding target 102 is a silicon (Si) wafer), laser light is easily reflected at the interface between the stage 112 and the bonding target 102. Therefore, to prevent such laser light reflection, an antireflection film may be formed on the mounting surface of the stage 112.

[0052] Similarly, the laser light is also reflected on the back surface of the stage 112 (the surface opposite the placement surface and in contact with the air outside the chamber 10) due to the difference in refractive index between the stage 112 and the air. Therefore, to prevent such laser light reflection, an anti-reflection film may be formed on the back surface of the stage 112.

[0053] [2] Joining objects and joining methods

[0054] [2-1] First embodiment

[0055] [2-1-1]Joining objects

[0056] Figure 2This is a conceptual diagram showing an example of two objects 101 and 102 that can be joined using the aforementioned joining apparatus. The objects 101 and 102 are, for example, semiconductor wafers or glass plates. On their joining surfaces 101a and 102a, a heat-absorbing layer 200 and metal layers 201 and 202 (joining material layers) for joining these surfaces 101a and 102a are formed as described below.

[0057] On the joining surface 101a of the joining object 101, a heat absorption layer 200 is formed along the joining surface 101a (heat absorption layer forming step). Furthermore, a metal layer 201 is formed along the surface of the heat absorption layer 200 (joining material layer forming step). Furthermore, on the joining surface 102a of the joining object 102, a metal layer 202 is formed along the joining surface 102a (joining material layer forming step). Regarding the relationship between the "first joining object" and the "second joining object" in the claims, the joining object 101 corresponds to the "first joining object," and the joining object 102 corresponds to the "second joining object."

[0058] Here, metal layer 201 is a bonding material layer mainly composed of one of two metals that produce a eutectic reaction, and metal layer 202 is a bonding material layer mainly composed of the other metal. Examples of the combination of the two metals include a combination of aluminum (Al) and germanium (Ge), a combination of copper (Cu) and tin (Sn), a combination of silver (Ag) and tin (Sn), and a combination of indium (In) and tin (Sn).

[0059] On the other hand, the metals mentioned above that produce eutectic reactions often have difficulty absorbing laser light efficiently. For example, metals such as aluminum (Al), silver (Ag), and gold (Au) have high reflectivity and therefore have difficulty absorbing laser light efficiently. Furthermore, because germanium (Ge) is a metal that partially transmits light (with a transmittance of approximately 30%), if either metal layer 201 or 202 uses germanium (Ge) as its primary component, and the metal layer has a thickness on the order of the wavelength of light, light diffraction occurs within the metal layer, thereby hindering the absorption of the laser light. Therefore, variations in the thickness of the metal layer (e.g., variations in film thickness of approximately ±10%) can lead to variations in the laser light absorption efficiency of the metal layer, and thus variations in the bonding state. For these reasons, technologies that use lasers to produce eutectic reactions have the problem of difficulty in efficiently heating the target metal layers 201 and 202, and the problem that reflected or transmitted laser light may adversely affect the sensor 103, etc.

[0060] Therefore, in this embodiment, the aforementioned heat absorption layer 200 is formed to enable efficient use of laser light. Specifically, heat absorption layer 200 is a layer primarily composed of a material that absorbs laser light more readily than the metals constituting metal layers 201 and 202. More specifically, heat absorption layer 200 is a layer primarily composed of at least one of titanium (Ti), chromium (Cr), and their oxides. While titanium (Ti) and chromium (Cr) have higher reflectivity than germanium (Ge), they transmit little light due to the aforementioned stretching phenomenon, allowing them to stably absorb approximately 40% of the incident laser light as heat. Furthermore, the material constituting heat absorption layer 200 is not limited to titanium (Ti), chromium (Cr), and their oxides; various materials that absorb laser light more readily than the metals constituting metal layers 201 and 202 can be used as appropriate. Examples of such materials include those obtained by dispersing a heat-absorbing material such as carbon in a resin.

[0061] With such a heat absorption layer 200, even when the metal layers 201 and 202 contain a metal that does not easily absorb laser light as a main component, and therefore it is difficult to efficiently heat the metal layers 201 and 202 by irradiating the metal layers 201 and 202 with laser light, the heat absorption layer 200 can be irradiated with laser light, thereby efficiently absorbing the laser light and indirectly heating the metal layers 201 and 202 via the heat absorption layer 200.

[0062] Furthermore, the various layers described above can be formed by vacuum film formation (including sputtering and vapor deposition) or coating of various materials on the bonding surfaces 101 a and 102 a , but the present invention is not limited thereto.

[0063] Figure 2 While the schematic diagram shows a case where metal layer 201 is formed over the entire area of ​​bonding surface 101a, and metal layer 202 is formed over the entire area of ​​bonding surface 102a, in actual semiconductor device (MEMS, etc.) manufacturing processes, metal layers 201 and 202 are patterned into various shapes depending on the device's shape, application, and other factors. In this case, heat absorption layer 200 may also be patterned into the same shape as metal layer 201. Figure 3 (A) and Figure 3 (B) is a cross-sectional view and a top view showing an example of the pattern shape of the metal layers 201 and 202. Figure 3(B) is a top view of only metal layer 202, of metal layers 201 and 202. In this example, metal layers 201 and 202 are formed into a rectangular frame shape surrounding each sensor 103, thereby sealing each sensor 103 within the device. Heat absorbing layer 200 is also formed in the same shape as metal layer 201. The pattern shapes of metal layers 201 and 202 are not limited to rectangular frames and can be modified as appropriate depending on the device shape, application, and other factors.

[0064] [2-1-2] Joining method

[0065] Next, the above-mentioned objects to be joined 101 and 102 (see Figure 2 ) The joining method of joining is explained. Figure 4 This is a flowchart illustrating the bonding method according to the first embodiment. The bonding method according to this embodiment includes a lamination step and a bonding treatment step performed using the aforementioned bonding apparatus. The lamination step and the bonding treatment step are described in detail below. Furthermore, the bonding method according to this embodiment may also include at least one of a heat absorption layer formation step for forming the aforementioned heat absorption layer 200 and a metal layer formation step for forming the aforementioned metal layers 201 and 202.

[0066] In the lamination step, the objects to be joined 101 and 102 are stacked so that the heat absorbing layer 200, the metal layer 201, and the metal layer 202 are sandwiched between their joining surfaces 101a and 102a. Specifically, the objects to be joined 101 and 102 are placed on the stage 112 of the joining apparatus (see FIG. 112 ) so that such a state is achieved. Figure 1 ).

[0067] During the bonding process, laser light is irradiated onto the heat absorbing layer 200, and the heat absorbed by the heat absorbing layer 200 from the laser light heats the metal layers 201 and 202. (The heat absorbing layer 200 uses the heat absorbed by the laser light to heat the metal layers 201 and 202.) This heating causes a eutectic reaction between the two metals, causing the metal layers 201 and 202 to bond together, thereby bonding the bonding surfaces 101a and 102a of the two bonding targets 101 and 102 together.

[0068] Specifically, the control unit 4 of the bonding apparatus moves the first and second chamber-forming sections 11 and 12 closer together, integrating them into one, while the two bonding objects 101 and 102 are placed on the stage 112, thereby forming the chamber 10. Furthermore, the control unit 4 controls the exhaust unit 14 to reduce the internal pressure of the chamber 10 until the chamber 10 is in a vacuum state. Thereafter, the control unit 4 controls the pressurizing mechanism 2 to apply pressure to the back surface 101b of the bonding object 101 via the diaphragm 21. Furthermore, while maintaining this pressure, the control unit 4 controls the laser light source 3 to irradiate the heat absorption layer 200 with laser light through the stage 112. Furthermore, the control unit 4 scans the laser light in a horizontal plane along the pattern of the intervening layer (e.g., the metal layer 201), thereby heating the entire area of ​​the bonding objects 101 and 102 via the heat absorption layer 200. Then, the metal layers 201 and 202 are bonded together by utilizing the eutectic reaction thus generated, thereby bonding the bonding surfaces 101 a and 102 a of the two bonding objects 101 and 102 to each other.

[0069] According to such a bonding method, as described above, the heat absorption layer 200 can efficiently absorb laser light, thereby indirectly heating the metal layers 201 and 202 via the heat absorption layer 200 . Therefore, efficient bonding using laser light can be achieved.

[0070] [2-1-3] Modification

[0071] <First Modification>

[0072] The above-described bonding method is not limited to bonding utilizing a eutectic reaction (eutectic bonding). It is also effective in bonding two objects 101 and 102 using at least one bonding material layer, such as bonding using a material with high reflectivity or high light transmittance, soldering, or welding. This bonding material layer can be heated using the heat absorption layer 200. In this case, during the bonding material layer formation step, the bonding material layer can be formed along at least one of the surface of the heat absorption layer 200 and the bonding surface 102a of the object 102.

[0073] <Second Modification>

[0074] In the above-described bonding method, if it is desired to further improve the heat absorption efficiency of the heat absorption layer 200 , the surface of the heat absorption layer 200 may be subjected to a treatment to increase the surface roughness, such as chemical treatment or sandblasting, before the lamination step (surface treatment step).

[0075] <Third Modification>

[0076] In the above-described bonding method, when at least one of the bonding objects 101 and 102 contains a material with high thermal conductivity as a main component, there is a problem in that the heat generated by the heat absorption layer 200 absorbing the laser light diffuses into the bonding object, thereby preventing efficient heating of the metal layers 201 and 202 .

[0077] To prevent such heat diffusion, a heat diffusion prevention layer may be formed on the bonding surface of the bonding objects 101 and 102 that primarily contain a material with high thermal conductivity (a heat diffusion prevention layer formation step). In this case, during the heat absorption layer formation step and the metal layer formation step, a heat absorption layer 200 and a metal layer 202 are formed on the surface of the heat diffusion prevention layer.

[0078] <Fourth Modification>

[0079] The above-described bonding method is not limited to formal bonding, in which all contact portions of the metal layers 201 and 202 are bonded using a laser, but can also be used for temporary bonding, in which a few contact portions of the metal layers 201 and 202 are bonded using a laser. Temporary bonding is performed to maintain the positional relationship of the bonding objects 101 and 102, adjusted by a positioning mechanism (not shown), so as to prevent them from collapsing due to vibration during transport.

[0080] In the above-mentioned joining method, the joining device is not limited to the joining method as long as it can irradiate the joining portion with laser light while clamping and pressing the joining objects 101 and 102. Figure 1 The bonding apparatus is exemplified, but other bonding apparatuses may be used.

[0081] [2-2] Second embodiment

[0082] [2-2-1]Joining objects

[0083] Figure 5 1 is a conceptual diagram showing another example of two bonding objects 101 and 102 that can be bonded using the above-mentioned bonding device. The bonding objects 101 and 102 are, for example, semiconductor wafers or glass plates, and a bonding material layer 203 can be formed along either of their bonding surfaces 101a and 102a (bonding material forming process). Here, the bonding material layer 203 is a layer containing at least one of titanium (Ti), chromium (Cr) and their oxides as main components. In particular, with respect to the relationship with the "first bonding object" and the "second bonding object" described in the claims, it can be considered that the bonding object 101 is equivalent to the "first bonding object" and the bonding object 102 is equivalent to the "second bonding object", or conversely, it can be considered that the bonding object 102 is equivalent to the "first bonding object" and the bonding object 101 is equivalent to the "second bonding object". In addition, the bonding material layer 203 can also be formed on both the bonding surfaces 101a and 102a.

[0084] Titanium (Ti), chromium (Cr), and their oxides are metals that easily absorb laser light, as described in the first embodiment. The inventors of the present invention have discovered that by using titanium (Ti), chromium (Cr), or their oxides having such properties to form the bonding material layer 203, even without the metal layers 201 and 202 that are bonded by a eutectic reaction as in the first embodiment, the bonding surfaces 101a and 102a of the two bonding objects 101 and 102 can be bonded to each other using only the bonding material layer 203.

[0085] Therefore, by using the above-mentioned bonding material layer 203 and irradiating the bonding material layer 203 with laser light, the bonding material layer 203 can efficiently absorb the laser light, thereby bonding the bonding surfaces 101 a and 102 a of the two bonding objects 101 and 102 to each other.

[0086] [2-2-2] Joining method

[0087] Next, the objects 101 and 102 to be joined are joined using a laser. Figure 5 ) is described. The bonding method of this embodiment is similar to Figure 4 The flow chart shown also includes a lamination process and a bonding process performed using the above-mentioned bonding apparatus. The lamination process and the bonding process are described in detail below. Furthermore, the bonding method of this embodiment may also include a bonding material layer forming process for forming the above-mentioned bonding material layer 203.

[0088] In the lamination process, the objects to be joined 101 and 102 are overlapped so that the bonding material layer 203 is sandwiched between the bonding surfaces 101a and 102a. Specifically, the objects to be joined 101 and 102 are placed on the stage 112 (see FIG. 112 ) of the bonding apparatus so that the bonding surfaces 101a and 102a are overlapped. Figure 1 ).

[0089] In the joining process, the joining material layer 203 is irradiated with laser light, and the joining material layer 203 absorbs the laser light, thereby heating the joining material layer 203. The heating of the joining material layer 203 joins the joining surfaces 101a and 102a of the two joining objects 101 and 102 to each other.

[0090] Specifically, the control unit 4 of the bonding apparatus forms the chamber 10 by bringing the first chamber forming unit 11 and the second chamber forming unit 12 closer together while the two bonding objects 101 and 102 are placed on the stage 112. Furthermore, the control unit 4 controls the exhaust unit 14 to reduce the internal pressure of the chamber 10 until the chamber 10 becomes a vacuum state. Thereafter, the control unit 4 controls the pressurizing mechanism 2 to apply pressure to the back surface 101b of the bonding object 101 through the diaphragm 21. Furthermore, the control unit 4 controls the laser light source 3 while maintaining the pressure applied to irradiate the bonding material layer 203 with laser light through the stage 112. Furthermore, the control unit 4 heats the bonding material layer 203 over the entire area of ​​the bonding objects 101 and 102 by scanning the laser light in a horizontal plane along the pattern shape of the bonding material layer 203. Then, by heating the bonding material layer 203 , the bonding surfaces 101 a and 102 a of the two bonding objects 101 and 102 are bonded to each other.

[0091] According to such a joining method, the joining material layer 203 can efficiently absorb the laser light as described above, thereby joining the two joining objects 101 and 102 , thereby achieving efficient joining using the laser light.

[0092] [2-2-3] Modification

[0093] <Fifth Modification>

[0094] In the above-mentioned bonding technique, similarly to the first embodiment, a thermal diffusion prevention layer may be formed on the bonding surface of the bonding object in order to prevent heat diffusion to the bonding object (prevention layer forming step).

[0095] <Sixth Modification>

[0096] The above-mentioned joining technique is not limited to formal joining as in the first embodiment, and can be used for temporary joining. In addition, in the above-mentioned joining method, if the joining device can clamp and press the joining objects 101 and 102 while irradiating the joining portion with a laser, it is not limited to Figure 1 The bonding apparatus is exemplified, but other bonding apparatuses may be used.

[0097] It should be understood that the description of the above embodiments and modifications is illustrative in all respects and does not limit the present invention. The scope of the present invention is indicated not by the above embodiments and modifications but by the claims. Furthermore, the scope of the present invention includes the equivalents of the claims and all modifications within the scope.

[0098] In addition, according to the above-mentioned embodiments and variations, as the object of the invention, not only the above-mentioned bonding method can be obtained, but also a part of the process constituting the bonding method (for example, the stacking process, the bonding processing process), the bonding device used in the bonding method, etc. can be obtained.

[0099] Description of Reference Signs

[0100] 1 chamber mechanism

[0101] 2 Pressurizing mechanism

[0102] 3 Laser light source

[0103] 4. Control Unit

[0104] 10 chambers

[0105] 1111st chamber component

[0106] 12 Second chamber component

[0107] 13 drive unit

[0108] 14 Exhaust

[0109] 21 diaphragm

[0110] 22 drive unit

[0111] 101, 102 joint objects

[0112] 101a, 102a joint surface

[0113] Back of 101b

[0114] 103 sensors

[0115] 111 First cylindrical part

[0116] 112 stage

[0117] 121 Second cylindrical part

[0118] 122 top plate

[0119] 200 heat absorption layer

[0120] 201, 202 metal layer (bonding material layer)

[0121] 203 bonding material layer

[0122] 221 transmission medium.

Claims

1. A bonding method, comprising: a laminating step of overlapping the first and second objects to be joined so that the heat absorbing layer and the joining material layer are sandwiched between the joining surfaces of the first and second objects to be joined; and The joining process step includes irradiating the heat absorption layer with laser light, heating the joining material layer with heat absorbed by the heat absorption layer from the laser light, and thereby joining the first joining target and the second joining target with the joining material layer.

2. The bonding method according to claim 1, wherein: The heat absorption layer contains at least one of titanium (Ti), chromium (Cr), and oxides thereof as a main component.

3. The bonding method according to claim 1 or 2, wherein: The method further includes a surface treatment step of increasing the surface roughness of the heat absorption layer before the lamination step.

4. A bonding method, comprising: a lamination step of overlapping the first joining object and the second joining object in such a manner that a joining material layer is sandwiched between joining surfaces of the first joining object and the second joining object, wherein the joining material layer contains at least one of titanium (Ti), chromium (Cr) and oxides thereof as a main component; and The joining process step heats the joining material layer by irradiating the joining material layer with laser light, thereby joining the first joining target and the second joining target using the joining material layer.

5. The bonding method according to any one of claims 1 to 4, wherein: A thermal diffusion prevention layer is formed on at least one of the joining surfaces of the first joining target and the second joining target.

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