JP2006222436A - Bonding method, and device created by the method and bonding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bonding technique for bonding without needing energy wave processing under a high vacuum and bonding under a continued high vacuum. <P>SOLUTION: After forming a bonding part made of metal in a contour-like shape and etching (surface activation processing) the bonding part by plasma, by bonding objects to be bonded each other by pushing and breaking a deposition layer which re-adhered to the bonding part, a space formed by being surrounded in the contour-like shape by the bonding part between bonding surfaces can be sealed into a predetermined atmosphere. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a joining technique for joining a plurality of objects having metal joints at room temperature.

  Conventionally, in the room temperature bonding method, after bonding surfaces are cleaned by an energy wave that is an atomic beam, an ion beam, or plasma, bonding is performed in a vacuum as shown in Patent Document 1 or is not performed as shown in Patent Document 2. The joining was in an active gas. This is because, when the bonding surface is exposed to the atmosphere, atoms of metals do not attract each other due to redeposition such as oxidation and organic matter.

  In the case of Patent Document 2, since gold does not react, oxidation can be prevented, but organic substances are attached. Therefore, the bonding is performed in an inert gas.

  In addition, the bonding surfaces are bonded to each other with a low load in a state where the surface accuracy is improved by polishing to the order of several nanometers. This is because if the surface accuracy is on the order of several nanometers, bonding proceeds naturally by intermolecular force in a vacuum.

Japanese Patent No. 2791429 JP 2001-351892 A

  However, the conventional method requires bonding in a vacuum, and at least in the atmosphere, bonding is difficult due to the reattached film. Also, since bonding is performed only by contact with a low load, it is necessary to increase the surface accuracy to the order of a few nanometers, and it is applied to semiconductor wafers and chips after multiple thin film treatments and heat treatments that do not undulate or have surface accuracy Is not suitable.

  Accordingly, an object of the present invention is to provide a joining technique for joining without requiring energy wave treatment under high vacuum and continuous joining under high vacuum.

  In order to solve the above-described problems, a joining method according to the present invention is a joining method for joining objects to be joined each having a joining portion made of metal, wherein at least one of the joining portions is formed in a contour shape, and the both joining is performed. After the surface is activated by plasma, the bonded portions are brought into contact with each other and pressed to break the bonded layer made of organic matter or oxide film reattached to the bonded portion, and the bonded object A space surrounded by the contour by the joint between the joint surfaces is sealed in a predetermined atmosphere (claim 1).

  Moreover, the joining apparatus concerning this invention is a joining apparatus which joins the to-be-joined objects which have a junction part which consists of metals, The head holding one said to-be-joined object, and the stage holding the other to-be-joined object And a vertical drive mechanism capable of controlling the pressure of at least one of the head or the stage in a direction substantially perpendicular to the bonding surface of the object to be bonded, and at least one of the bonding portions is formed in a contour shape, After the surfaces of both the joints are activated by plasma, the objects to be joined, in which the adherent layer made of an organic substance or an oxide film is reattached to the joints, are pressed against each other. The space formed by the joint portion surrounded by the contour between the joint surfaces of the objects to be joined is sealed in a predetermined atmosphere (claim 15).

  In the present invention, the treatment with plasma refers to a treatment for joining in a solid phase at a low temperature by activating a joining interface of an object to be joined with plasma. This treatment is also called surface activation treatment, and the bonding principle by surface activation can be considered as follows. That is, if the object to be bonded is a metal-like material, the organic matter or oxide film on the bonding surface is removed by etching to generate dangling bonds of active metal atoms on the bonding surface. Bonding is made by dangling bonds on the bonding surface of objects. Further, if the metal is gold, it is difficult for organic substances and oxide films to be reattached to the bonding surface, and bonding is possible within a few hours even in a vacuum atmosphere.

As shown in Patent Document 1, deposits such as oxide films and organic substances on the bonding surface (bonding portion) of the bonded object are obtained by performing surface activation treatment with energy waves in a high vacuum of 10 ⁻⁵ Torr or less. If it is removed and in a high vacuum, it can be joined by contacting it as it is. However, when the objects to be bonded are bonded together in a low vacuum of 10 ⁻⁵ Torr or higher after air cleaning or after alignment between the objects to be bonded, the bonding surfaces are oxidized. Since an adhering layer such as a film or an organic material is re-formed, even if it is brought into contact, it is not bonded as it is. However, immediately after the surface activation treatment, the adherent layer is thin even if it is reattached, so if pressure is applied and the adherent layer is pushed through and joined, the joining interface expands, and a new surface appears on the joining surface. The joints are joined together.

  Therefore, after forming a joint portion made of metal in a contour shape and etching the joint portion with plasma (surface activation treatment), the adherend layer reattached to the joint portion is pushed through to join the objects to be joined together. Thus, a space formed by the joint portion between the joint surfaces surrounded by a contour can be sealed in a predetermined atmosphere. Even when compared with a solder which is a conventional method capable of metal bonding at a low temperature, bonding is possible even at a melting point of solder of 183 ° C. or lower, further 150 ° C. or lower.

  In addition, since the objects to be bonded can be bonded in a vacuum atmosphere or an enclosed gas atmosphere, it is possible to perform the processes of bonding, evacuation, gas replacement, and sealing in one process with one apparatus. In addition, since the surface (joint part) is activated by etching with plasma and the deposit layer reattached to the joint part is pushed through and joined by atomic force, the objects to be joined even at room temperature of room temperature to 180 ° C or less. Can be joined. Although joint strength increases when heating at about 150 ° C. is used in combination, even if heating is performed at a temperature lower than 150 ° C., the joint strength is sufficiently higher than conventional heat diffusion bonding.

  Note that the surface activation of the objects to be bonded by plasma and the process of bonding the objects to be bonded may be performed by separate apparatuses. With such a configuration, the object to be joined after being treated with plasma by the surface activation device is transported to the joining device, and in the joining device, such as an oxide film or an organic substance reattached to the joining portion during transportation. The objects to be joined can be joined by pushing through the deposit layer.

  In addition, after the surface activation treatment of the objects to be bonded, particularly when alignment of the objects to be bonded is performed in the air or when the objects to be bonded are transferred to the bonding apparatus through the air, an oxide film is formed on the bonding portion. And deposits such as organic matter tend to reattach. However, as described above, the objects to be joined can be joined to each other by pressurizing and pressing the reattached adherent layer.

  Moreover, the joining method and joining apparatus which perform without exposing to the air | atmosphere from the surface activation process of a to-be-joined object to joining may be sufficient. With such a configuration, since the process is performed from surface activation to bonding without being exposed to the atmosphere, it is difficult for the deposit to reattach to the object to be bonded after the surface activation.

  Further, a bonding apparatus that performs a part from the surface activation process to the bonding process may be used. By performing the entire process from the surface activation process to the bonding process of the object to be bonded, it is possible to further prevent reattachment of floating substances to the bonded part. Further, if the surface activation process and the bonding process are performed in the same chamber, reattachment of floating substances to the bonded portion can be further prevented, and at the same time, the apparatus can be made compact and the cost can be reduced.

  It should be noted that even if the process for surface activation of the objects to be bonded by plasma and the process for bonding the objects to be bonded are performed with separate apparatuses, the integrated apparatus incorporating the function of performing both processes is used. You can go.

  Further, the space may be sealed in a vacuum atmosphere by bonding the objects to be bonded together in a vacuum (claim 2).

  Further, the head, the stage, and the vertical drive mechanism may be provided in a decompression chamber, and the space may be sealed in a vacuum atmosphere by bonding the objects to be bonded together in a vacuum (claim). Item 16).

  With such a structure, after etching (surface activation treatment) of the bonded portion with plasma, the space is easily sealed in a vacuum atmosphere by bonding the objects to be bonded together in a vacuum. Can do. Further, if the surface activation process and the bonding process are performed in the same chamber, it is preferable that after the surface activation process, the reaction gas is discharged, vacuumed, and bonded in a vacuum.

  Moreover, the structure which seals the said space by the said enclosed gas atmosphere by joining the said to-be-joined objects in enclosed gas may be sufficient (Claim 3).

  Further, in the decompression chamber, the head, the stage, and the vertical drive mechanism are provided, the inside of the decompression chamber is replaced with an enclosed gas, and the objects to be joined are joined in the enclosed gas, The space may be sealed in the sealed gas atmosphere (claim 17).

  With such a configuration, after etching (surface activation treatment) of the bonding portion with plasma, the objects to be bonded are bonded together in the sealed gas, thereby easily sealing the space in the sealed gas atmosphere. can do. Further, if the surface activation process and the bonding process are performed in the same chamber, it is preferable that after the surface activation process, the reaction gas is discharged and replaced with the sealed gas, and then bonded in the sealing gas as it is. .

  In addition, the joining method and joining apparatus whose sealing gas is Ar gas and nitrogen gas may be sufficient. It is preferable that the enclosed gas is Ar gas or nitrogen gas because the device is not affected by corrosion or the like. In addition, if the sealed gas is Ar gas, it is preferable that the reaction atmosphere used for the surface activation treatment can be used as it is when the bonding portion is surface activated by Ar plasma.

  Moreover, the structure which joins the said to-be-joined objects in a solid phase under the low temperature heating of room temperature-180 degrees C or less may be sufficient (Claims 4 and 18).

  In the present invention, room temperature bonding means a method of bonding at room temperature to 180 ° C. or lower, preferably at room temperature, and since the melting point of lead tin solder is 183 ° C. in conventional low temperature bonding, the temperature is lower than that. It is effective to be able to join with. Also, bonding at 150 ° C. or lower and 100 ° C. or lower is preferable, and it is even better if it is at room temperature.

  With such a configuration, when the objects to be joined are made of different materials, if they are joined by melting and diffusing such different materials, they become brittle or weak in material. The objects to be joined can be joined in a solid state by joining under a low temperature heating of room temperature to 180 ° C. or less. Therefore, it is possible to join objects to be joined that cannot withstand joining at high temperatures due to distortion caused by thermal expansion due to a combination of heat-sensitive devices and dissimilar materials. In addition, when the object to be joined is melted, the molten metal does not spread evenly, and therefore, there is a problem that when the object is solidified, the molten metal is pulled in the direction where there is a lot of molten metal, resulting in misalignment. Therefore, it is effective to be able to join in a solid phase.

  Moreover, the structure whose hardness of the said junction part is 20Hv-200Hv may be sufficient (Claim 5). Moreover, the structure which joins the to-be-joined objects whose hardness of the said junction part is 20Hv-200Hv may be sufficient.

  As described above, the adhered layer is thin even if it is reattached immediately after the surface activation treatment, so if the adhered layer is pushed through and joined, the joining interface spreads and a new surface appears on the joining surface. The joints are joined together. In order to make it easy to push through the deposit layer, the hardness of the bonding metal of the bonded portion of the bonded object must be low. As a result of various experiments by the present inventors, it has been found that it is particularly effective for room temperature bonding that the hardness of the bonded portion is 200 Hv or less, preferably 20 Hv to 200 Hv in terms of Vickers hardness (see FIG. 1).

  FIG. 1 shows the result of a joint strength comparison experiment according to the hardness of the joint. As an experimental condition, surface activation treatment was performed by using Ar plasma as plasma and irradiating it with 100 W intensity for 30 seconds. After the surface activation treatment, the object to be bonded was pressure bonded in an Ar atmosphere. As a result, Ni plating with a joint hardness of 300 Hv and chrome plating with 600 Hv were poorly bonded, but good when copper, gold, or Al, which is a metal with a Vickers hardness of 200 Hv or less, was used as the joint. A good bonding strength was obtained. If the region is further limited, it can be considered that the Vickers hardness connecting the curves in FIG. In addition, when it joined by the intensity | strength of 30 g / bump or more corresponding to 80% of maximum intensity | strength, it was set as the area | region with favorable joining, and when it joined by the intensity | strength of 15 g / bump or less, it was judged that it was a joining defect. In the case of surface bonding such as a wafer, the tensile strength is indicated, and if the strength is 20 MPa or more, it may be judged good, and if the strength is 10 MPa or less, it may be judged as defective.

Further, if the bonding was performed immediately after the plasma treatment, gold and copper could be bonded even in the atmosphere. In particular, the same strength as the bonding strength in the Ar atmosphere was obtained even after gold exposure for 1 hour. Further, it has been found that when the objects to be bonded are bonded to each other, the objects to be bonded can be bonded more strongly by applying a pressure of 150 Mpa or more to the objects to be bonded by a pressurizing means. At this time, when the metal constituting the joint portion was gold, copper, or Al, the joint was particularly effective.

  Moreover, the structure which the said junction part is gold | metal | money may be sufficient (Claim 6). Moreover, the structure which joins the said to-be-joined objects comprised by the said junction part with gold | metal | money may be sufficient (Claim 20). With such a configuration, particularly gold is an effective metal having low hardness and being not oxidized in the air, so that there are few deposits. As will be described later, even if it is exposed to the atmosphere, it can be joined within a few hours.

  Further, if the joint is made of gold, the joint does not corrode or generates gas, which is suitable as a sealing material for sealing the atmosphere. In addition, since the melting point is very high, the reliability at a high temperature after joining in a solid phase at a low temperature is high and suitable. As described above, gold can be bonded in the air or in a sealed gas within a certain time after the surface activation. Further, in the present invention, gold may be only the bonding surface. A soft material can also be selected as the base material of the joint for the portion that increases the height.

  In addition, since the bonding portion is made of gold, it is not corroded even in a vacuum or in an inert gas, and foreign matter adhesion can be suppressed for a certain period of time. Therefore, the objects to be joined can be joined even in a sealed gas other than an inert gas.

  The joining portion of the object to be joined is formed by forming a gold film on the surface of a base material having a hardness of 200 Hv or less. After joining the objects to be joined, the gold film is used as the base material. It may be configured to diffuse (claims 7 and 21). As described above, as long as the bonding surface (the surface of the bonding portion) is gold, bonding is effective because it is possible to bond in the atmosphere in which organic substances and the like are not easily reattached after plasma treatment. If the gold film is diffused in the base material after joining the objects to be joined, since the base materials are joined to each other after joining, the strength is high and the material can be made of a uniform material. As a method of diffusing, it can be diffused even at room temperature if it takes time. Moreover, if heat is applied even at a low temperature, it can be diffused more quickly. Diffusion means that particles consisting of molecules and atoms move and spread, and that particles diffuse into the facing material and the base material at the bonding interface.

  Moreover, the joining method and joining apparatus which make the gold | metal | money or gold | metal film | membrane which comprises the junction part of at least one to-be-joined object 100Hv or less by annealing may be sufficient. As described above, in order to crush and follow the joint, it is preferable that the joint hardness is lowered and softened. Therefore, it is preferable that the hardness of the gold plating, which is usually 120 Hv or more, is 100 Hv or less by annealing. Moreover, it is more preferable to set it as 60 Hv or less.

  Further, the object to be bonded is a semiconductor or a MEMS device including a plurality of metal bumps in which the bonding portion is made of copper as the base material and a gold film is formed on the surface of the base material. After joining the joined objects, the gold film may be diffused into the base material (claims 8 and 22). In electrical functional devices such as semiconductors and MEMS devices, switching from current capacity to conventional Al electrodes to copper electrodes is desired. However, with copper bumps, the bonding temperature is high and practically difficult. Therefore, the surface of the base material made of copper is covered with a gold film, so that the bonding can be performed at a low temperature, and an atmosphere that is not vacuum such as in gas or in the atmosphere can be selected. After that, if gold is diffused in the base material, it becomes a joint between copper and the purpose can be achieved.

  Further, the gold or the gold film constituting the bonding portion of at least one of the objects to be bonded may be a gold plating having a thickness of 1 μm or more. Further, the gold or the gold film constituting the bonding portion of at least one of the objects to be bonded may be configured to bond objects to be bonded which are gold plating having a thickness of 1 μm or more (claim 23). With such a configuration, as a method of absorbing waviness and surface roughness of the joint surface (joint portion) of the object to be joined, at least one of the joint surfaces is crushed with a certain height so that the gap is filled and copied. Can. Therefore, it is effective to plate one gold to 1 μm or more.

In addition, the surface roughness Ry of the bonding portion of at least one of the objects to be bonded may be 120 nm to 2 μm (claim 10). Moreover, it is good also as a structure which joins the said to-be-joined objects whose surface roughness Ry of the said junction part of at least one said to-be-joined object is 120 nm-2 micrometers (Claim 24). Here, the surface roughness indicates minute irregularities within a certain area excluding waviness. For example, the maximum value and the minimum value of minute irregularities in 10 μm ² are shown. As shown in Patent Document 1, an object such as an oxide film or an organic substance on a bonding surface is removed by cleaning an object to be bonded with an energy wave in a vacuum. it can. However, when it is transported in the air after cleaning or joined in a low vacuum with a lot of air and suspended matter, an adhering layer is formed on the joining surface. . However, since the deposit layer is also thin immediately after cleaning, it can be bonded by the following method.

  This is because, as shown in FIG. 2 (a), by forming minute irregularities on the joining surface, the convex portions are crushed and spread by pressurization, and a new surface appears and is joined (FIG. 2 (b)). reference). Further, considering microscopically, as shown in FIGS. 3 (a) and 3 (b), the crystal orientation is rotated and the new surface appears when the convex portions are crushed. As shown in FIG. 4, a sufficient bonding strength can be obtained when the surface roughness of the minute irregularities is 120 nm or more. In this measurement method, metal protrusions to be a plurality of bumps are provided on an object to be bonded, the shear strength after bonding is measured, and the shear strength per bump is indicated. The bump used was a gold-plated 40 μm square with a height of 15 μm. As a sufficient shear strength, 30 g / bump, which is 80% or more of the maximum strength, was used as a guide.

  Moreover, it is preferable to use a bonding method and a bonding apparatus in which the surface roughness Ry of at least one bonding surface is 120 nm or more and 2 μm or less. If the unevenness of the bonding surface (bonding portion) of the object to be bonded becomes too large, the crushing amount is about several μm at the maximum, so the contact area becomes small and the bonding strength decreases. As can be seen from FIG. 4, when the thickness is 2 μm or more, sufficient bonding strength cannot be obtained, and it is preferably 120 nm or more and 2 μm or less.

  Further, the bonding surface of the objects to be bonded may be a plurality of metal protrusions, and a bonding method and a bonding apparatus in which the tips are convex may be used. In the bonding between surfaces, as described above, each bonding portion has a convex shape so that micro unevenness is effective, and even if a plurality of bonding portions are used, the bonding area is lower than the surface bonding, but the same effect can be obtained. .

  Further, Ar plasma using a reactive gas as Ar gas is used as the plasma for surface activation treatment of the object to be bonded, and the bonding surface of the object to be bonded is etched by the Ar plasma. Rough joining methods and joining devices may be used. When cleaning an object to be bonded using Ar plasma, if the cleaning time is set to be long, the bonding surface is roughened by performing, for example, usually 30 seconds for 3 minutes. The roughness can be exactly 120 nm or more, which is effective.

  In addition, the head for holding one of the objects to be bonded, the stage for holding the other object to be bonded, and the position of at least one of the head or the stage in a direction substantially perpendicular to the bonding surface of the objects to be bonded. And a vertical drive mechanism capable of pressure control, and when joining the objects to be joined, after joining, the vertical drive mechanism is driven to pressurize the objects to be joined. The vertical driving mechanism may be stopped and a joining method may be used in which the height of the head from the stage is kept constant for a certain period of time.

  Further, the vertical drive means is configured to be capable of controlling the position of at least one of the head or the stage in a direction substantially perpendicular to the bonding surface of the objects to be bonded, and when bonding the objects to be bonded, At the time of bonding, the vertical driving mechanism is driven to pressurize the objects to be joined, and then the vertical driving mechanism is stopped to keep the height of the head from the stage constant for a certain period of time. It may be.

  Here, the height of the head from the stage refers to the distance between the objects to be bonded in the process of pressing the object to be bonded held by the head against the object to be bonded held by the opposite stage and crushing the bonded portion to a micro level. To express. Keeping the height of the head from the stage constant means keeping the distance between the objects to be joined constant. When joining the objects to be joined, since the unevenness of the joint surface is elastically deformed in a state of being momentarily pressurized, the interface crystal may not rotate. Further, the elastic deformation remains as residual stress and acts in a direction to peel off the bonding force, so that the bonding strength is lowered. As a method to prevent this, the head height is kept constant for a certain period of time, and at the joint interface, the crystal cannot rotate with the load, the crystal orientation is rotated, the particles move, and a new surface appears. The residual stress is removed by bonding and movement of the particles. When the pressure is controlled, the height decreases and the elastic deformation always occurs, so the crystal orientation does not shift. However, when stopped at a certain height, the crystal orientation begins to deviate from elastic deformation, and the crystal orientation begins to collapse over time. As a result, a new surface appears and contributes to bonding.

  Further, a head height detection means may be provided in the head portion positioned at the tip of the vertical drive mechanism so as to be a joining device that controls the height when stopped. A configuration may be adopted in which a head height detecting means is provided and the head height is kept constant in the submicron order. Considering the microscopic joint interface, the elastically deformed joint interface is released by the rotation of crystal orientation and the movement of particles. If there is an elastic deformation point on the ball of the bolt / nut mechanism part of the Z elevating mechanism (vertical drive mechanism), even if the drive motor is stopped, it will enter the elastic deformation mode again. In order to solve this, a height detection means is provided in the head part, and the height is controlled to be constant on the submicron range. By doing so, the elastic deformation is gradually eliminated and the bonding strength is increased. FIG. 5 shows the degree of increase in bonding strength after the head stops.

  The head structure capable of pressurization control and position control can be constituted by a ball screw and a servo motor in which pressure detection means are arranged in series. Further, it is possible to arrange the position detecting means in the cylinder and enable the pressurization control and the position control by the servo valve. As long as pressurization control and position control are possible, the present invention is not limited to the above-described configuration, and any method may be used as the pressurization unit and the position control unit.

  Moreover, it is good also as the joining method and joining apparatus which make the said stop time 1 second or more. As shown in FIG. 5, this stop time was effective from 1 second or more depending on the material and the bonding state, and there was no change after 2 minutes or more.

  Moreover, it is good also as a joining method and a joining apparatus provided with a heating means and heating at 180 degrees C or less at the time of the said stop. When heat is applied during the stop, the crystal orientation is rotated and the particles are moved efficiently, the bonding proceeds, and the residual stress is removed, thereby increasing the bonding strength. FIG. 6 shows the heating temperature and bonding strength when the head is stopped. As the heating temperature, a low temperature heating of 180 ° C. or lower was sufficient.

  Moreover, after leveling the said junction part of the said to-be-joined object, the joining method of joining after processing the said junction part of each said to-be-joined object with the said plasma may be sufficient.

  Moreover, after leveling the said junction part of at least one said to-be-joined object, after processing the said junction part of each said to-be-joined object with the said plasma, the joining apparatus which joins may be sufficient (Claim 25).

  With such a configuration, as shown in FIG. 7, even in the air, after dry cleaning (plasma treatment), if not left, pressurization can be performed at room temperature in a solid phase by applying pressure. This is presumably because a thin adhesion layer is formed on the bonding surface, but the thickness of the adhesion layer is such that it can be pushed by pressure. In addition, because of the room temperature, a load approximately twice that of heating was required to crush the bumps and bring them into contact with each other. However, in the case of leveled bumps, pressurization of 300 MPa was necessary if not, whereas sufficient bonding strength could be obtained with a pressure of 150 MPa. In order to make sure that the objects to be bonded come into contact with each other, it is necessary to crush the bonding surface roughness etc. of the objects to be bonded. This requires pressure depending on the bump height variation and the surface roughness. Because it becomes. A normal bump had a height variation of 2 μm. However, after leveling, the height variation was 120 nm or less. Therefore, it is considered that the bonding load could be reduced. Here, the leveling means that bumps are applied to a smoothing means such as a reference table having a flatness as shown in FIG. 10 with respect to the surface roughness of the bump surface shown in FIG. 8 and the height variation between the bumps shown in FIG. Indicates that the height and surface roughness are uniformly corrected by pressing. After the leveling, the objects to be joined are joined as shown in FIG. In this example, it is composed of a substrate having a bumped chip and a pad, but it may be another bonded material.

  Moreover, it is good also as a structure performed before joining this to-be-joined object by the said to-be-joined object which opposes the said leveling (Claim 12).

  Further, after the leveling is performed by abutting the objects to be bonded, which are respectively held opposite to the head and the stage, the bonding portions of the objects to be bonded are treated with the plasma, and then bonded. It is also possible to adopt a configuration (claim 26).

  With such a configuration, since leveling is performed using the object to be bonded, the leveling can be performed in accordance with the characteristics of the surface unevenness of the object to be bonded. For this reason, it is possible to reduce the bonding load even for an object to be bonded that has no surface. For example, in the case of a build-up board in which wiring layers are stacked, the height of the upper electrode pad varies slightly depending on the position due to the lower wiring pattern.

  Moreover, it is good also as a joining method and a joining apparatus which both to-be-joined objects have metal bumps (joining part), and join the metal bumps which gave leveling to each other. If the objects to be joined are leveled, the joining surfaces can be joined with each other without unevenness, so that the joining load can be further reduced. When measured in the same manner as in FIG. 7, the bonding load could be reduced to 100 MPa or less.

  Moreover, it is good also as a structure provided with the energy wave irradiation means to generate the said plasma (Claim 27). In this case, it is assumed that the plasma according to the invention described in claim 15 uses means provided outside the apparatus. However, if the structure as in claim 27 is adopted, the surface of the object to be bonded by plasma is used. It is possible to execute collectively from the activation process to the bonding process between the objects to be bonded. As a result, for example, the surface activation process and the bonding process can be performed in one chamber, and the space of the apparatus can be saved.

  Further, a bonding method in which the object to be bonded is a chip or a wafer made of a semiconductor or a MEMS device may be used.

  A device such as a semiconductor device or a MEMS device formed by the bonding method according to any one of claims 1 to 13 (claim 14).

  Flip chip bonding of a semiconductor chip having a large number of electrode portions to be metal protrusions is required to have a thermal effect on the semiconductor and high precision mounting within a few μm from a fine pitch electrode. The demand for joining is high, and the present invention is particularly effective.

  The bonding object may be a bonding method and a bonding apparatus in which the bonding object is provided with metal protrusions on at least one bonding object, and the at least one bonding object is a semiconductor chip. Further, the semiconductor device may be a semiconductor device manufactured by the above method in which the object to be bonded is provided with metal protrusions on at least one object to be bonded, and at least one object to be bonded is a semiconductor chip. Flip chip bonding of a semiconductor chip having a large number of electrode portions to be metal protrusions is required to have a thermal effect on the semiconductor and high precision mounting within a few μm from a fine pitch electrode. The demand for joining is high, and the present invention is particularly effective.

  In addition, it is preferable that a semiconductor device can be made to have a three-dimensional structure by bonding semiconductors to each other and a semiconductor device with a higher degree of integration can be obtained. Further, it is preferable to join with a wafer and then dice into chips to increase production efficiency.

The plasma may be a low-pressure plasma. If the surface activation treatment is performed by an ion beam or an atomic beam, a high vacuum atmosphere of about 10 ⁻⁸ Torr is required, and the equipment is burdened. By using plasma, the degree of vacuum is about 10 ⁻² Torr, so that the surface activation process can be performed with simple equipment. As a result, the apparatus is downsized and the cost is reduced. Further, it is more preferable to use Ar as a reaction gas for generating plasma because it is inactive and has high etching ability. Further, it is preferable that the pressure is reduced to 10 ⁻³ Torr or less in order to remove the reaction gas and the etched product after cleaning (plasma treatment) of the object to be bonded. Heating at about 100 to 180 ° C. can be used in combination to remove reaction gas such as Ar implanted in the bonding surface (bonding portion) of the object to be bonded.

  Further, at least one of the objects to be bonded is a semiconductor, and the bonded portion of each of the objects to be bonded is plasma-cleaned by the reduced-pressure plasma generated by an electric field generated by an alternating power source that switches + and-directions. A bonding method may be used in which the bonded objects are bonded at room temperature in a solid phase.

  Further, at least one of the objects to be bonded is a semiconductor, and the bonded portion of each of the objects to be bonded is plasma-cleaned by the reduced-pressure plasma generated by an electric field generated by an alternating power source that switches + and-directions. It may be a joining apparatus that joins joined objects at room temperature in a solid phase.

  In the case where at least one of the objects to be bonded is a semiconductor, when + ions or −electrons collide with the circuit surface of the semiconductor, the circuit, particularly the gate oxide film, may be charged up. In order to avoid this, it is possible to neutralize before charge is charged by colliding + ions and − electrons alternately. By doing so, it becomes possible to avoid charge-up damage. If the deposit on the bonding surface is removed by etching and activated by plasma, the metal, Si, and oxide can be bonded in a solid phase at a low temperature.

  Further, a bonding method and a bonding apparatus in which the alternating power source is switched evenly from 1: 5 may be used. The charge-up damage can be reduced if the ratio of switching alternately is more than 1: 5. Moreover, it is more preferable if it is more equal than 1: 2.

  The alternating power supply includes a bonding method and a bonding apparatus in which Vdc is a negative value and a positive region is 20% to 40%. Further, since Ar, oxygen plasma, and the like become + ions, in order to accelerate and collide with the cleaning surface and perform etching, the electrode that holds the object to be bonded needs to be a negative electric field. Therefore, the Vdc value is preferably −. Here, Vpp indicates a peak-to-peak in the AC waveform of the voltage, and Vdc indicates a bias voltage that is an offset value from 0 V of the voltage value that is the center of Vpp.

  The alternating power source may be an RF plasma generating power source capable of adjusting a bias voltage Vdc value. If the +/- of the alternating power source is made too uniform, the chance of + ions colliding decreases and the cleaning ability (surface activation ability) decreases. Also, charge-up damage due to electrons occurs. Therefore, it is preferable that the optimum Vdc value can be adjusted for each application, so that optimum cleaning ability can be exhibited without causing charge-up damage.

  Further, by using an RF plasma generating power source composed of alternating current as shown in FIG. 26 as an alternating power source, it is possible to easily switch the electric field alternately between + and-. Further, the ratio of + and − can be easily adjusted by adjusting the Vdc value.

  The alternating power supply may be a pulse wave generating power supply capable of adjusting a pulse width. As the alternating power source, a pulse wave generating power source as shown in FIG. 27 can be used. If it is a pulse wave, sharp rise and fall are possible, and the cleaning ability is also improved.

  In addition to adjusting the Vdc value, as shown in FIG. 28, by adjusting the pulse width and interval, the ratio of + − and the collision time can be managed, so that the setting can be made more finely than the RF that is an alternating current. Easy to find value.

Further, it is preferable that the degree of vacuum is 10 ⁻³ Torr or less during the plasma cleaning or before or after the cleaning. In order to remove impurities, it is preferable that the pressure is reduced to 10 ⁻³ Torr or less before washing. Further, it is preferable to reduce the pressure to 10 ⁻³ Torr or less in order to remove the plasma reaction gas and the etching product after or during the cleaning. In addition, heating at about 100 to 180 ° C. can be used in combination to remove a reactive gas such as Ar implanted into the bonding surface. Further, during the cleaning, the reaction gas may be supplied from one side of the object to be bonded and the reaction gas may be sucked from the other side. With such a configuration, since the reaction gas can flow in one direction on the surface to be bonded, the deposits scattered during the plasma cleaning can be efficiently removed, and the reattachment of the removed items to the workpiece is reduced. It can be effective.

  Further, the head and the stage in the present invention are each provided with a workpiece holding means, and in order to join uniformly without contact, an elastic material is disposed on the surface of at least one of the workpiece holding means, It is preferable to pressurize both objects to be bonded via an elastic material when bonding the bonded objects. In the bonding method of the present invention, since the metal is bonded in a solid phase rather than being melted and bonded like solder, if the parallelism or flatness between the objects to be bonded is not present, the bonding can be performed only at the contact point. . Therefore, by arranging an elastic material on the surface of at least one object holding means and pressurizing both objects to be bonded through the elastic material at the time of bonding, the parallelism between the objects to be bonded is made uniform and thin. Flatness can be made uniform if it is a workpiece. Further, after bringing the object to be bonded into contact, the elastic material may be inserted between the object to be bonded and the object holding means.

  In addition, at least one of the objects to be bonded holding means is held by a spherical bearing, and when the objects to be bonded are bonded or before bonding, the objects to be bonded are contact-pressed so that at least one of the objects to be bonded has the other inclination. preferable. The object holding means is held by the stage and / or the head with a spherical bearing, and the objects to be bonded are contact-pressed during bonding of the objects to be bonded or before bonding so that at least one of the objects to be bonded has the other inclination. By adopting such a structure that can be joined, it is possible to join the objects to be joined in parallel with each other (see FIG. 29). The spherical bearing has a lock mechanism for selecting lock / free, and may be configured to be free only when it is normally locked in a locked state. In addition, once the parallelism is leveled, the spherical bearing is locked, and after maintaining the state, it can be plasma-processed to align the objects to be joined and then joined. Therefore, it is preferable because the bonding can be performed without positional deviation when the objects to be bonded are bonded.

  In addition, an ultrasonic vibration head including a horn, a horn holding portion, and a vibrator is provided, and ultrasonic vibration having an amplitude of 2 μm or less is applied to an object to be bonded at the time of bonding in the atmosphere, a load of 150 MPa or less, 180 ° C. A method and a bonding apparatus for metal bonding in a solid phase by the following heating may be used. When ultrasonic vibration is applied at the time of joining in the atmosphere, joining becomes easier. Since the surface has already been activated, the ultrasonic energy may be small, and an amplitude of 2 μm or less that can suppress damage and displacement is sufficient. Moreover, it is more preferable if it is 1 micrometer or less. Further, by applying ultrasonic waves, the bonding load can be lowered to 150 MPa or less, which is half or less. When gold metal protrusions are bonded, bonding cannot be performed unless they are crushed at a high pressure of about 300 MPa at room temperature. When this bump is on the surface of the semiconductor circuit, it is generally damaged depending on the circuit at 200 MPa or more. The experimental condition is that when a semiconductor chip using a gold bump with a 50 μm square, 20 μm height and 1 μm bump height variation to be a metal protrusion on the semiconductor chip is ultrasonically bonded onto a gold thin film substrate and at room temperature bonding In the case of normal temperature bonding, bonding was possible for the first time at 80 g / bump, but when ultrasonic waves were applied, bonding was possible with a load of 40 g / bump or more. Therefore, it can be seen that it is necessary to crush bumps of 1 μm or more as a bump crushing allowance. In the case where a bump having a height of 20 μm is formed by gold plating, it is necessary to crush the bumps of this degree because it is the limit to suppress the height variation to 1 μm.

  Further, between the cleaning under reduced pressure and the bonding in the atmosphere, at least one of the objects to be bonded is carried into a cleaning chamber, and the cleaned objects to be bonded are transported to a bonded portion, and are connected during bonding. The joining method and joining apparatus which wash | clean a subsequent to-be-joined thing may be sufficient. Surface activation can be performed by individually plasma-treating an object to be bonded whose bonding surface is made of gold or copper in advance in a vacuum chamber, and the surface can be taken out into the atmosphere and metal bonded in a solid phase. By connecting the cleaned objects to be bonded to a bonded portion and cleaning the subsequent objects to be bonded during bonding, the cleaning time can be processed in parallel, so that the tact time can be increased. In addition, when the balance is not achieved one by one, it may be cleaned in a state where a plurality of trays are placed. Moreover, if it is a to-be-joined object on a continuous reel, what is necessary is just to carry out plasma processing by inserting | pinching through a packing in a chamber door.

  Further, in a state where the bonding surfaces of the objects to be bonded are not arranged to face each other in a chamber under reduced pressure, after the bonding portion is treated with the plasma, at least one of the objects to be bonded is moved. In addition, after the joint surfaces are arranged to face each other, at least one of the objects to be joined is moved in a direction substantially perpendicular to the joint surface to bring the joint portions into contact with each other, A joining method may be used in which the objects to be joined are joined in a solid phase.

  In the vacuum chamber, the head, the stage, the vertical drive mechanism, and a moving means for moving at least one of the stage or the head to the side, the energy wave irradiation means, In the vacuum chamber under reduced pressure, bonding surfaces of the objects to be bonded are arranged to face each other by the moving means in the vacuum chamber under reduced pressure. After the joint is treated with the plasma, the at least one of the objects to be joined is moved so that the joining surfaces face each other, and further, by the vertical drive mechanism, By moving at least one of the objects to be bonded in a direction substantially perpendicular to the bonding surface and bringing the bonding portions into contact with each other, How to be a bonding apparatus for bonding the solid phase.

  Conventionally, when the plasma treatment is performed with both objects to be bonded facing each other, there has been a problem that one etched deposit reattaches to the other. Therefore, in the present invention, in the state where the bonding surfaces of the objects to be bonded are not opposed to each other, the above-described reattachment can be prevented by performing the plasma treatment on the bonding portion and then moving the bonding portion to the opposite position and bonding them. It becomes. Deposits etched by plasma cleaning (processing) in a state where the stage is slid to the standby position scatter to the opposite surface and do not reattach to the other.

Moreover, it is good also as a joining method and joining apparatus which make a vacuum degree below 10 < ^-3 > Torr at the time of the said plasma cleaning (process). It is preferable to set the degree of vacuum to 10 ⁻³ Torr or less because the probability that scattered matter collides with ions, changes direction and reattaches is reduced.

  Moreover, it is good also as a joining method and a joining apparatus which the clearance gap between the to-be-joined objects after sliding to the said joining position is less than 20 mm. Conventionally, in order to generate plasma, it is necessary to separate the upper and lower workpieces by at least about 30 mm. Therefore, when the head is lowered, even if it is aligned with the inclination of the Z-axis (vertical drive mechanism) or backlash, it will be misaligned. There was a problem of causing. However, if the plasma is generated on the head side and the stage side while the stage is slid to the standby position, the Z-axis movement distance can be minimized, so the distance between the objects to be joined can be reduced. It can be set to 20 mm or less which is 30 mm or less. Moreover, it can set to 5 micrometers or less, and is more preferable. If it is kept within a few μm, the error due to the tilt of the Z axis can be ignored, and the error in the horizontal direction due to the Z movement is also minimized in proportion to the amount of movement.

  Further, since plasma can be generated by sliding, a metal to be sputtered is disposed on the facing surface of the object to be bonded, and the metal is used as a plasma electrode, so that the metal is sputtered on the surface of the object to be bonded and a thin film is formed. If metal films are sputtered on the surfaces of both objects to be bonded, the metals can be bonded together. As a result, Al, ceramics, oxides, etc., which are difficult to join by conventional surface activation, can be applied and can be joined. Further, it becomes easier to perform bonding by etching and cleaning the bonding surface of the bonded object in advance using the bonded object side as a plasma electrode before sputtering. In addition, after the slide, it is possible to perform sputtering on the other object to be bonded facing the object to be bonded having one metal surface as the electrode side in a state where the objects to be bonded are arranged to face each other. It is particularly suitable when one is a metal made of gold or copper that is easy to join and the other is a material that is difficult to join.

  Further, when the bonding portion is treated with plasma, a metal electrode is disposed at a position opposite to the bonding surface of at least one of the objects to be bonded, and the metal electrode is formed on the bonding surface of the object to be bonded by sputtering. It is good also as a structure which forms the metal film which consists of the metal which comprises this, and joins the said to-be-joined objects in a solid-phase.

  A bonding method and a bonding apparatus may be used in which a metal film is formed on the bonding surface of the other object made of a hard metal such as Ni, oxide, Si, or ceramic, and the metals are bonded together in a solid phase. A metal to be sputtered is disposed at a position facing the bonding surface of the object to be bonded, and the metal is irradiated with plasma, and the metal is sputtered on the surface of the object to be bonded to form a thin film. If metal films are sputtered on the surfaces of both objects to be bonded, the metals can be bonded to each other in a solid phase. Conventionally, it can be applied to hard metals such as Ni, ceramics, oxides, Si, etc., which were difficult to join by surface activation, and can be joined. If the plasma is a low-pressure plasma, sputtering can be performed by using a plasma electrode as the metal. Further, by using a plasma electrode on the workpiece side before sputtering, it becomes easier to bond if the bonding surface of the workpiece is etched and cleaned (plasma treatment) in advance. Moreover, it can also sputter | spatter with respect to the other to-be-joined object which opposes the to-be-joined object which has one metal surface in the state arrange | positioned facing as an electrode side. It is particularly suitable when one is a metal made of gold or copper that is easy to join and the other is a material that is difficult to join.

  Also, at the time of surface activation by plasma, a metal film made of gold or copper is formed on the other bonding surface by sputtering the surface metal made of gold or copper of one object to be bonded, It is good also as a joining method and joining apparatus which join at normal temperature. When the sputtered metal is gold or copper, it can be bonded at room temperature in the solid phase in the atmosphere.

  In the surface activation treatment by plasma, it is effective to etch at least 1 nm because deposits existing on the surface of the object to be bonded are deposited to 1 nm or more in several seconds when exposed to the atmosphere even after wet cleaning.

  Further, the present invention may be a bonding method and a bonding apparatus in which the gold constituting the bonded portion of at least one object to be bonded is annealed to have a hardness of 100 Hv or less.

  As described above, in order to crush and follow the joint, it is preferable to reduce the hardness of the joint and soften it. Therefore, it is preferable that the hardness of gold, which is usually 120 Hv or more, is 100 Hv or less by annealing. Moreover, it is more preferable to set it as 60 Hv or less.

  Further, if the object to be bonded is a wafer, it is preferable that a plurality of devices can be bonded at once. After bonding, dicing may be performed to obtain individual pieces.

  Further, the present invention may be a bonding method and a bonding apparatus in which the object to be bonded is a device including a surface acoustic wave device, an RF device, or the like. Semiconductor devices such as semiconductor devices, surface acoustic wave devices, RF devices, and MEMS devices having mechanical movable parts are particularly required to be sealed, and these are vulnerable to heat. Further, since it is made of a combination of different materials, distortion occurs due to thermal expansion, and there is a problem that it cannot withstand joining at high temperatures, which is suitable for this method. Further, there has been no conventional bonding method for these devices that dislike gas and moisture from the resin within 200 ° C. In addition, these devices are suitable because the surfaces thereof vibrate or have an actuator that moves mechanically in MEMS, so that they cannot be bonded by resin and are required to be directly bonded. As a form, it is most effective to handle and bond them on a wafer, which is a semiconductor manufacturing process, but it is also suitable in a chip state after dicing.

  Further, a configuration may be adopted in which the objects to be joined are joined in the atmosphere. With such a configuration, even in the atmosphere, the deposit layer is thin immediately after the surface activation treatment, so if it is pushed and joined, the joint interface of the joint will spread, and a new surface will appear and be joined . In terms of time, after the surface activation treatment, particularly when the joint is gold, oxidation, organic matter, and the like are difficult to reattach, so that the joining is easy within one hour.

  From the experimental results, the required heating temperature depends on the elapsed time after the plasma treatment of the joint, the type of gas, and the moisture content (humidity). If mounted (bonded) within 1 hour after exposure to the atmosphere, bonding was possible even with heating within 100 ° C. In this bonding method, although the solid phase is used, since the metal molecules are directly bonded to each other on the bonding surface, the metal molecules are only diffused even if heated to a high temperature, for example, 350 ° C. after bonding. The strength does not decrease and the resistance value does not increase, and the reliability is high even at high temperatures.

  Further, one of the objects to be bonded is a device that functions electrically using the bonding portion as an electrode, and a surface of the bonding portion is made of gold or copper, and the bonding portion of the bonding object to be bonded is the plasma. After cleaning by, after forming an adhesion layer with gas at the joint, contacting the joints made of metal electrodes in the atmosphere, after adjusting the device to an optimal position in an electrically functioning state, A bonding method in which solid-phase bonding is performed in a solid phase may be used.

  In addition, one of the objects to be bonded is a device that functions electrically using the bonding portion as an electrode, the head holding the functional device, the stage holding the other object to be bonded, The vertical drive mechanism that moves up and down at least one of the head or the stage, a probe that electrically functions the functional device, a recognition unit that recognizes the function of the functional device, and the functional device and the object to be joined An alignment table that corrects the relative position, and the surface of the joint is made of gold or copper, and the joint of the object to be joined is cleaned by the plasma and then attached to the joint by gas. A layer was formed, the joints made of metal electrodes were brought into contact with each other in the atmosphere, and the device was adjusted to an optimal position in a state where it electrically operated It may be a welding apparatus room temperature bonding in the solid phase.

  In order to mount the functional device by adjusting the position of the functional device efficiently and with high accuracy, the position of the functional device is adjusted in a state where the functional device is directly electrically operated while contacting the metal electrode during mounting, and then heated. It is effective to bond the metal electrode to the metal. As in the prior art, once it is replaced with an alignment mark, it contains an error, and is complicated and inefficient. Therefore, the surface of the bonding part of the functional device (the object to be bonded) is made of gold or copper, and both bonding surfaces are treated in a vacuum with plasma, and then an adhesion layer is attached to the bonding part with a gas, and the metal in the atmosphere. What is necessary is just to metal-bond in a solid phase by heating within 180 degreeC, after adjusting the junction part which consists of an electrode and adjusting the optimal position in the state which functioned the functional device electrically.

  As a method for solid-phase bonding between metals at room temperature, a method in which a bonding surface made of gold is treated with plasma in a vacuum and bonded in an inert gas atmosphere is effective. After the treatment, an adhesion layer is once formed with gas, and the metal electrodes are brought into contact with each other in the atmosphere, so that they cannot be joined only by contact. Therefore, it is possible to adjust the relative positions of the functional device and the object to be bonded while causing the functional device to function electrically. When the position adjustment is completed, both electrodes are metal-bonded only by applying low-temperature heating within 180 ° C. Thus, the melting temperature of lead-tin solder, which is a conventional low-temperature metal joint, can be set lower than 183 ° C. Moreover, in order to suppress the position shift by heating low, 150 degrees C or less is preferable. Moreover, it is more preferable if it is within 100 degreeC.

  Further, since the solder does not spread evenly when it is melted, there is a problem that when the solder is solidified, the object to be joined is pulled in a direction where there is much solder and a positional deviation occurs. Therefore, it is effective to be able to join objects (functional devices) in solid phase. From the data, the required heating temperature depends on the elapsed time after the plasma treatment of the joint, the type of gas, and the moisture content (humidity). If the adhesive layer was applied in the atmosphere and mounted within 1 hour, bonding was possible even by heating within 100 ° C. In this bonding method, although the solid phase is used, since the metal molecules are directly bonded to each other on the bonding surface, the metal molecules are only diffused even if heated to a high temperature, for example, 350 ° C. after bonding. The strength does not decrease and the resistance value does not increase, and the reliability is high even at high temperatures.

  In addition, as a gas for attaching an adhesion layer, a gas containing nitrogen, oxygen, He, hydrogen, fluorine, and carbon is not bonded by contact only by being adhered as compared with a gas such as inert Ar, and Bonding is possible at low temperatures.

  Moreover, the joining method and joining apparatus whose gas is air | atmosphere may be sufficient. It can be easily handled in the atmosphere, and the above effect can be expected.

In addition, as a cleaning method for an object to be bonded, plasma that requires about 10 ⁻² Torr is easier and more effective than an atomic beam or ion beam that requires a high vacuum of about 10 ⁻⁵ Torr. Further, etching is efficiently performed by using Ar as a reaction gas, and since Ar gas is inactive, it is suitable without forming a reaction product on the surface of the object to be bonded.

  One of the objects to be joined is a light emitting element, and a probe from a power source is brought into contact with the joint functioning as an electrode of the light emitting element so that the light emitting element is electrically functioned. The light emitting point may be recognized by the recognition means, and the position of the light emitting element may be adjusted to the optimum position, and then bonded at room temperature in the solid phase.

  Further, the light-emitting element may be a surface-emitting type, and may be a bonding method and a bonding apparatus that emit light in a direction perpendicular to the bonding surface of the light-emitting element and toward one of the objects to be bonded.

  In addition, one of the objects to be bonded is a light emitting element that emits light parallel to the bonding surface, and the probe is brought into contact with the electrode opposite to the bonding surface of the light emitting element, and the other probe is brought into contact with the other electrode to electrically It is also possible to use a bonding method and a bonding apparatus in which a light emitting point is recognized by a recognition means and the position of the light emitting element is adjusted to an optimum value and then metal bonding is performed in a solid phase by heating within 180 ° C. In particular, when the functional device is a light emitting element, the positioning of the light emitting point and the optical fiber is required to have submicron accuracy, and the present invention is effective in terms of accuracy. In the case of light-emitting elements, since heat is dissipated at the time of light emission, reliability at a high temperature of 250 ° C. or higher is required, and this bonding method is effective because it can be bonded at a low temperature and can maintain reliability at a temperature higher than the bonding temperature. is there.

  In the present invention, as shown in FIGS. 12 and 13, the present invention is effective in the case of a light emitting element such as a laser diode that emits light in parallel with the joint surface. In this case, as shown in FIGS. 12 and 13, the electrode which is the bonding surface of the light emitting element is set to the object to be bonded side, and the position is adjusted while moving up and down while holding the opposite surface. While pressing the lower electrode of the light emitting element against the upper electrode of the object to be bonded, the probe is brought into contact with the electrode on the light emitting element holding surface and the upper electrode on the object to be bonded side, thereby causing the light emitting element to function electrically. After adjusting the light emitting point to the optimum position, metal bonding is performed in a solid phase by heating within 180 ° C.

  In addition, the light emitting element is a surface light emitting type, emits light in a direction perpendicular to the bonding surface and to one bonded object side, and is a bonded surface that is a bonded electrode of the bonded object and an electrode on the surface of the light emitting element. , Contact the other end of the object to be joined and electrically function to recognize the light emitting point by the recognition means, adjust the position of the light emitting element to the optimum value, and then heat it at 180 ° C. in the solid phase. A bonding method and a bonding apparatus for metal bonding may be used. In the case of a light emitting device such as a surface emitting laser that emits light in a direction perpendicular to the bonding surface other than the light emitting device that emits light in parallel to the bonding surface as described above (see FIG. 13), the light emitting direction and Since the direction of the electrode can be on the lower side, it can be configured easily. In this case, as shown in FIG. 14, the light emitting surface is set to the object to be bonded side, and the opposite surface is held to adjust the position. Since the electrode is located on the same side as the light emitting surface, the probe is brought into contact with the electrode on the upper surface of the object to be bonded while being pressed against the electrode on the object to be bonded, thereby causing the light emitting element to function electrically. After adjusting the light emitting point to the optimum position, metal bonding is performed in a solid phase by heating within 180 ° C. If the optical fiber is not embedded and emits light downward, it can be recognized from the side by providing an optical path conversion means such as a prism on the stage.

  Further, the adjustment method to the optimum value may be a bonding method and a bonding apparatus that input light emitted from a light emitting element into an optical fiber, detect the input value, and adjust the position of the light emitting element. When inputting light to an optical fiber, it is effective to connect the other end of the optical fiber to a measuring device and monitor the output to align the maximum value. is there. Further, as a method for recognizing a light emitting point, a position where the light quantity is maximized is generally regarded as a light emitting point.

  In addition, the method includes a first step of recognizing the position of the object to be bonded by the bonding object recognizing means, and a light emitted from the light emitting element. May be a bonding method and a bonding apparatus that include a second step of reading a light-emitting point position by a matrix imaging element and a third step of adjusting the light-emitting element position based on the recognition result. In particular, when there is no input to the optical fiber or when the other end of the optical fiber cannot be connected, the position of the object to be bonded is first recognized by the object recognition means, and the position where the light emitting point should be recognized is recognized. Next, the light emitting point is directly input to the matrix image sensor, the input value is detected, and the optical element position is such that the position on the matrix image sensor where the light intensity is maximum is the target position on the matrix image sensor. This can be achieved by adjusting. The details will be described. First, the light emitting element is caused to emit light and read by the matrix imaging element to obtain the maximum light amount position on the matrix imaging element. Since the position of the matrix imaging device movably mounted on the table is known in advance, the light emitting point position of the light emitting device can be recognized. Therefore, since the position where the light emitting point position should be originally obtained is already known on the matrix image pickup element, the position of the light emitting element is corrected so that the light emission point comes to the position where the maximum light amount on the matrix image pickup element should be obtained. In addition, as a method of recognizing the light emission point by the matrix image pickup means, the position of the image sensor that is the maximum is generally regarded as the light emission point. It is preferable to recognize in units.

  The bonded object recognition means and the light emitting point recognizing means are separate matrix image sensors, and the relative position of each image sensor is recognized as a reference jig in which the light emitting point and the object mark position are determined. It may be a joining method and a joining apparatus that are recognized by calibration. The light emitting point recognizing means and the bonded object recognizing means are separate matrix image pickup devices, for example, when the magnification of the optical system is different. In that case, if the relative position between the individual matrix imaging elements is not known, it is not possible to know where the light emitting point should be brought even if the object mark is recognized. Therefore, the relative positional relationship can be calibrated if both are recognized using a reference jig in which the relative positions of the light emitting point and the object recognition mark are determined in advance. By doing so, it is possible to recognize even light emitting points and objects to be joined that have different sizes.

  Further, when the light emitting element is electrically functioned and the position of the light emitting point is recognized by the recognition means, a bonding method and a bonding apparatus that recognize light by intermittently emitting light may be used. In the case of a light-emitting element, heat is dissipated at the time of light emission, and thus heat is stored at about 250 ° C. when continuously emitted. In this case, joining at the time of position adjustment causes a position shift due to thermal expansion or the like. Therefore, by intermittently emitting light and capturing a light emission point instantaneously in synchronization with light emission, it is possible to prevent heat storage and recognize the light emission point at a low temperature.

  Also, a bonding method and a bonding apparatus in which an alignment mark is provided on both objects to be bonded, provided with an alignment mark recognizing means, position-corrected by the alignment marks of both objects to be bonded, and then electrically functioned to be adjusted to an optimum position. It may be. In recognizing the light emitting point, if the position accuracy is suddenly poor, it takes time to align the light emitting point if the positional deviation is large even if the light emitting element is contacted. In addition, the accuracy deteriorates because the field of view of the light emitting point recognizing means needs to be enlarged. For this reason, it is preferable to recognize the light emitting point from a state in which the alignment unit is previously recognized by using the alignment mark provided on the light emitting element and the object to be bonded, and then the position is corrected and coarsely positioned. Further, if there is an outer shape or a recognizable pattern without providing an alignment mark, it can be recognized as an alignment mark.

  Moreover, the light-emitting point recognition means and the to-be-joined object recognition means may be a joining method and a joining apparatus comprising the same recognition means. Moreover, the joining method and joining apparatus which hold | maintain at least one to-be-joined object with the tool with an optical path conversion means, and recognize a to-be-joined object and a light emission point from a side may be sufficient. In the case of a flat light emitting device, if the optical path is changed from the bottom to the side by holding it with a tool having an optical path changing means such as a prism or mirror, both the position of the object to be joined and the position of the light emitting point can be read from the side. It can also be a simple structure. In the case of a parallel light emitting element, the light emitting element is held by a tool having an optical path changing means, and the upper surface mark of the object to be bonded can be read from the side, resulting in a simple structure. The position of the object to be joined means that the position is determined by recognizing the light emitting element or the alignment mark or the outer shape on the substrate, and aligning in advance to recognize the mark on the substrate in order to determine the light emitting point position. Therefore, it is also used to recognize the alignment mark on the light emitting element and the substrate.

  If IR (infrared) light is used, at least one of the objects to be bonded can be transmitted and the alignment mark of the object to be bonded can be read. For example, in the case of a light-emitting element that emits light parallel to the bonding surface, the light-emitting element holding tool has an optical path conversion means, and the alignment mark can be read through the light-emitting element or the object to be bonded by recognizing with IR light. it can. The IR light source may use reflected light on the same axis, or may use transmitted light using a light source on the opposite side. The present optical path changing means may be provided on the workpiece holding stage side in addition to the holding tool. By using the optical path conversion means, it is possible to measure with higher accuracy if the recognition of the position of the object including the light emitting point and the light emitting element is recognized by the same recognition means from the same direction. For example, if the optical system of the light emitting point recognizing means recognizes the mark or the outer shape on the object to be joined, after recognizing the object to be joined, the position where the next light emitting point should come is easily known, and there is an individual recognition means. This is preferable because it does not change with time due to relative position error or thermal expansion. In addition, the apparatus can be simplified, and it can be simplified without the necessity of providing a multi-axis moving table in the recognition means, and can be further simplified by limiting the alignment table to either the head side or the stage side. Even if the matrix imaging elements are individually separated, an integrated structure can be obtained by branching the optical system from the middle.

  Further, in the light emitting module manufactured by the above-described bonding method, the light emitting element can be mounted efficiently and with high accuracy by the above-described method, and can be manufactured with high accuracy and at low cost, and the present invention is effective. is there.

  Further, in the bonding method, one of the objects to be bonded is a chip, and the other object to be bonded is a wafer on which the plurality of chips are mounted, and the plurality of chips are continuously bonded to the wafer. Also good.

  One of the objects to be bonded is a chip, and the other object to be bonded is a wafer on which a plurality of chips are mounted, and the bonding apparatus is configured to continuously bond the plurality of chips to the wafer. Also good.

  As shown in FIG. 7, even in the atmosphere, after dry cleaning (surface activation by plasma), if not left, pressurization can be performed at room temperature in a solid phase by applying pressure. This is presumably because a thin adhesion layer is formed on the bonding surface (bonding portion) of the object to be bonded, but the thickness of the adhesion layer is such that it can be punctured by pressurization. Also, since solder is heated to a high temperature when mounting multiple chips on a wafer, it also affects the solder on peripheral wafers, causing problems such as melting and oxidation, and bonding of chips to the soldered chips. However, in the present invention, since bonding can be performed at a solder melting temperature of 183 ° C. or lower, continuous mounting is possible without affecting the periphery. Moreover, since it can join in a solid phase, there is no position shift due to melting as described above. Incidentally, the chip that was not plasma-treated was not bonded. Note that a chip generally indicates a single side obtained by dicing a wafer, and includes mounted components such as transistors, resistors, capacitors, and reactances.

  Further, a bonding method and a bonding apparatus in which the bonding time between the chip and the wafer is within 2 seconds and the chips are continuously mounted may be used. When solder is heated and melted, and then separated from the chip until it is cooled and fixed, positional misalignment and solder are removed, so that continuous mounting of the chip takes time and production efficiency is not good. For example, the bonding time for one chip needs about 10 seconds. However, in the present invention, since bonding is performed by applying pressure, the bonding time can be extremely short. Thus, if the bonding time is 2 seconds or less and chips are continuously bonded onto the wafer, it is efficient. The joining time is preferably 1 second or less, and more preferably 0.5 seconds or less, because it is shorter than the joining by ultrasonic vibration joining.

  The wafer may be treated with the plasma again after a predetermined time while the chips are continuously bonded to the wafer, and then the chips are bonded to the wafer. In order to continuously bond a plurality of chips on one wafer, several hours are required if the number of chips is large. When bonding at room temperature in the air after dry cleaning (plasma activation treatment), if the bonding is not performed within about one hour, deposits on the bonding surface of the objects to be bonded increase and bonding cannot be performed. Therefore, it is preferable to dry-clean the object to be bonded with plasma such as reduced pressure plasma again within 1 hour, preferably within 30 minutes. For this reason, the cleaning machine (energy wave irradiation means) is docked with the bonding apparatus for bonding objects, and after a certain time has elapsed during chip bonding to the wafer, the wafer is once transported to the cleaning machine and re-cleaned. After cleaning, the wafer is set on the stage again and chip bonding is started. By doing so, even in a wafer to which a large number of chips are bonded, the chips can be bonded continuously at room temperature in the atmosphere.

  In addition, since a large number of electrode joints are joined by bumps in a semiconductor, damage occurs at a high temperature. Therefore, joining at a low temperature is desired. Further, in order to join bumps having a fine pitch smaller than about 50 μm, joining at a low temperature with suppressed thermal expansion is desired. Also, a low load is required due to damage to the circuit surface. Further, it is efficient if chips are continuously bonded onto the wafer. For these reasons, the present invention is preferred.

  By forming a joint made of metal in a contour shape, etching the joint with plasma (surface activation treatment), and then joining the objects to be joined by smashing the deposit layer reattached to the joint The space formed by the joint portion between the joint surfaces surrounded by the contour can be sealed in a predetermined atmosphere. In addition, the resin sealing material for the vacuum hole is not necessary, and the objects to be joined can be joined at a low temperature. Therefore, distortion due to thermal expansion is caused by a combination of heat-sensitive devices and dissimilar materials. Devices that cannot withstand bonding can be created.

<First Embodiment>
A first embodiment of the present invention will be described below with reference to the drawings. FIG. 15 shows a first embodiment of a joining apparatus according to the present invention. In this embodiment, an apparatus for bonding a chip 20 made of a semiconductor as a first object to be bonded and a substrate 22 as a second object to be bonded is taken as an example. The bonding surface of the chip 20 has a metal electrode 20a made of gold as an electrode, and the metal electrode 22a as an electrode is disposed on the bonding surface of the substrate 22 at a position facing the chip-side metal electrode 20a. The chip side metal electrode 20a and the substrate side metal electrode 22a are bonded together by being pressurized.

  The joining apparatus is roughly composed of a joining mechanism 27 including a vertical drive mechanism 25 and a head unit 26, a mounting mechanism 28 including a stage 10 and a stage table 12, a position recognition unit 29, a transport unit 30, and a control device 31. The vertical drive mechanism 25 moves the head portion 26 up and down while being guided by the vertical guide 3 by the vertical drive motor 1 and the bolt / nut mechanism 2. The head portion 26 is guided in the vertical direction by the head escape guide 5, cancels its own weight, and detects the applied pressure while being pulled by the head weight counter 4 for pushing against the applied pressure detecting device 32. 32 and the vertical drive mechanism 25 are grounded.

  The head unit 26 includes a chip holding tool 8 that sucks and holds the chip 20 and a tip tool 9, a head-side alignment table 7 that performs position correction with a translation axis of translational movement and rotational movement, and a head holding part 6 that supports them. Has been. A heating heater is embedded in the chip holding tool 8. The mounting mechanism 28 includes a stage 10 that holds the substrate 22 by suction, and a stage table 12 that has a movement axis for parallel movement and rotational movement for aligning the position of the chip and the substrate. A stage heater 11 is built in the stage 10. The joining mechanism is coupled to the frame 34 and is connected to the gantry 35 around the center of pressure by the four support columns 13.

  The position recognizing unit 29 is inserted between the opposed chip and the substrate, and the upper and lower mark recognizing means 14 and the upper and lower mark recognizing means 14 for recognizing the alignment marks for recognizing the positions of the upper and lower chips and the substrate are arranged horizontally and / or. It comprises a recognition means moving table 15 that moves up and down. The transport unit 30 includes a substrate transport device 16 that transports the substrate 22, a substrate transport conveyor 17, a chip supply device 18 that transports the chips 20, and a chip tray 19. The control unit 31 includes overall control of the apparatus and an operation unit. Particularly in the pressure control, the torque of the vertical drive motor 1 is controlled by a signal from the pressure detection means 32 to control the pressure related to the joining.

  Next, a series of operations will be described. The chip 20 is supplied from the chip tray 19 to the chip holding tool 8 by the chip supply device 18 and is sucked and held. The substrate 22 is supplied from the substrate transfer conveyor 17 to the stage 10 by the substrate transfer device 16 and held by suction. The upper and lower mark recognition means 14 is inserted by the recognition means moving table 15 between the chip 20 and the substrate 22 whose holding surfaces are opposed to each other, and the alignment marks for alignment between the chip 20 and the substrate 22 facing each other are placed on the upper and lower mark recognition means 14. To recognize the position. With the chip 20 as a reference, the position of the substrate 22 is aligned and moved in the translational and rotational movement directions by the stage table 12. During alignment, the position may be corrected with the stage table 12 and the head side alignment table, or the position may be corrected with only the head side alignment table. Moreover, the structure of only one of the tables may be used.

  The upper and lower mark recognizing means 14 is retracted by the recognizing means moving table 15 in a state where the joining positions of the chip 20 and the substrate 22 are aligned. Next, the head portion 26 is lowered by the vertical drive mechanism 25, and the chip 20 and the substrate 22 are grounded. The position of the head portion 26 in the height direction is detected by the head height detecting means 24. The contact timing of the chip 20 and the substrate 22 is detected by the pressure detection means 32, and the vertical drive motor is switched from position control to torque control. The head height is monitored by the head height detection means 24 even during pressurization switched to torque control, and the position in the height direction can also be controlled. After the bonding is completed, the suction of the chip 20 is released and remains on the stage with the chip 20 mounted on the substrate 22 side. This is again discharged to the substrate transfer conveyor 17 by the substrate transfer device 16 and the series of operations is completed.

  In order to perform metal bonding in a solid state at a low temperature of 180 ° C. or lower in the atmosphere, the bonding surface (bonding portion) of the object to be bonded (chip 20, substrate 22) made of metal in advance in a vacuum, an atomic beam, Etch (clean) several nm with an energy wave that is an ion beam or plasma to remove deposits. In the case of bonding in the air after cleaning (surface activation treatment), an adhering layer is formed on the bonding surface, so even if they are brought into contact, they are not bonded as they are. However, since the deposit layer is thin immediately after cleaning, the deposit layer is crushed by pressurization, and the deposit layer is crushed and a new surface appears and is joined. In the present embodiment, since the gold having a Vickers hardness of 60 Hv is adopted as the bonding portion, the chip 20 and the substrate 22 are firmly bonded even at room temperature as shown in FIG.

Second Embodiment
Next, a second embodiment of the bonding apparatus according to the present invention will be described in detail with reference to FIG. The present embodiment is greatly different from the first embodiment in that the bonding portion of the object to be bonded is formed by forming a gold film on the surface of the base material made of metal, and the other configuration is the first. This is the same as the embodiment. Hereinafter, the second embodiment will be described in detail focusing on the differences from the first embodiment. In addition, about the structure and operation | movement same as 1st Embodiment, the description of the structure and operation | movement is abbreviate | omitted.

  In the second embodiment, the joint between the chip 20 and the substrate 22 is configured as follows. In other words, a plurality of copper is used as the base material 20b, 22b, and metal bumps 20c, 22c are formed on the surface of the base material 20b, 22b. The metal bumps are subjected to surface activation treatment with energy waves, then bonded in the air, and heated at a low temperature to diffuse gold. FIG. 16A shows a joint formed by forming a gold film using copper as a base material. FIG. 16B shows how the gold films 20c and 22c are diffused into the base materials 20b and 22b by low-temperature heating after joining the joint shown in FIG. 16A. If the bonding surface is gold, it is difficult for organic substances and the like to reattach to the bonding surface after the surface activation treatment, and bonding in the air is possible within a few hours. As described above, if the gold film is diffused in the base material after the room temperature bonding, the base materials are bonded to each other after the bonding, so that the strength is high and the material can be made of a uniform material. As a method of diffusing, it can be diffused by leaving it at room temperature. Moreover, diffusion can be accelerated more quickly by heating at a low temperature. In this embodiment, the gold films 20c and 22c could be diffused into the base materials 20b and 22b by heating at 150 ° C. for 2 hours.

  Further, when the object to be bonded is an electrical functional device in a semiconductor or a MEMS device, switching from a conventional Al electrode to a copper electrode is desired due to the current capacity. However, with copper bumps, the bonding temperature is high and practically difficult. Therefore, as in this embodiment, the surface of the base material made of copper is covered with a gold film, so that the bonding can be performed at a low temperature, and a non-vacuum atmosphere such as gas or air can be selected. So it is effective. After that, if gold is diffused in the base material, it becomes a joint between copper and the purpose is achieved.

<Third Embodiment>
Next, a third embodiment of the joining apparatus according to the present invention will be described in detail. The main difference between the present embodiment and the first and second embodiments is that minute irregularities are formed on the surface of the joint, and other configurations and operations are the same as those of the first and second embodiments. This is the same and will not be described. Hereinafter, a configuration unique to the present embodiment will be described in detail.

  According to the present embodiment, the convex portions are crushed and spread as shown in FIG. 2 by pressurization when joining the objects to be joined, and a new surface appears and is joined. Further, considering microscopically, as shown in FIG. 3, the crystal orientations arranged side by side are crushed and the crystal orientation is rotated, and a new surface appears. As shown in FIG. 4, a sufficient bonding strength can be obtained when the surface roughness of the minute irregularities is 120 nm or more.

  In addition, in the bonding between surfaces, as described above, even if a plurality of convex bonding portions are used, the bonding area is lower than the surface bonding, but the same effect can be obtained so that the micro unevenness is effective. . Moreover, in order to crush and join the micro unevenness, the hardness of the joining metal must be low. In this embodiment, since gold is employed as the bonded portion with a hardness of 200 Hv or less, it was possible to bond firmly. In addition, even if copper or Al was used as the bonding portion, the bonding could be effectively performed. Moreover, it was able to join more firmly that the applied pressure at this time is 150 Mpa or more. In particular, when the joint portion is made of gold, it is effective because it has low hardness and does not oxidize in the atmosphere.

  In addition, when cleaning the bonding portion using Ar plasma (surface activation treatment), if the cleaning time is set to be long, the bonding surface is roughened by performing, for example, usually 30 seconds for 3 minutes. If the object to be bonded is cleaned using Ar plasma for the time that the roughness can be set to 120 nm or more, surface activation treatment and minute irregularities are formed on the surface of the bonded portion. Work can be performed at the same time, which is efficient.

<Fourth embodiment>
Next, the fourth embodiment will be described in detail. Hereinafter, differences from the first to third embodiments will be described, and description of the same configurations and operations as those of the first to third embodiments will be omitted.

  In the third embodiment, in the state where the object to be bonded is momentarily pressed, the unevenness of the bonding surface (bonding portion) is elastically deformed, and therefore the interface crystal may not rotate. Further, the elastic deformation remains as residual stress and acts in a direction to peel off the bonding force, so that the bonding strength is lowered. As a method for preventing this, by making the head height of the head portion 26 constant for a certain period of time, at the joining interface of the object to be joined, the microscopic rotation of the crystal orientation is performed because the load cannot withstand the load. Movement occurs, a new surface appears and joins, and residual stress is removed by the movement of the particles. As shown in FIG. 5, this stop time was effective from 1 second or more depending on the material and the bonding state, and there was no change after 2 minutes or more.

  Further, when heating is performed at 180 ° C. or less during the stop, the crystal orientation is rotated and the particles are efficiently moved, the bonding proceeds, and the residual stress is removed, thereby increasing the bonding strength. As the heating temperature, a low temperature heating of 180 ° C. or lower was sufficient. In addition, flip chip bonding of a semiconductor chip having a large number of electrode portions to be metal protrusions is required to have a high precision mounting within a few μm from a fine pitch electrode, due to thermal effects on the semiconductor, and 180 ° C. or less, preferably at room temperature There is a high demand for joining at low temperatures, and this embodiment is particularly effective.

  Although the embodiment of the chip and the substrate has been described as an embodiment, the object to be bonded may be a material other than a semiconductor. In addition, gold, Al, copper, and the like are suitable for the joint, but any other metal or other metal can be used as long as it can be surface activated.

  The semiconductor chip may be in any form such as a chip or a wafer. The metal protrusions may have a plurality of independent shapes, or may have a connected shape confining a certain region. Further, the entire surface may be a bonding surface.

<Fifth Embodiment>
Subsequently, a fifth embodiment of the present invention will be described in detail. The main difference between the present embodiment and the first to fourth embodiments is that the chip 20 is a light emitting element. Hereinafter, a configuration unique to the present embodiment will be described in detail. FIG. 12 is a diagram for explaining a method of aligning a side light emitting element and a PLC (Planner Light wave guide Circuit) substrate with a V groove for fixing the fiber, and FIG. 13 is a side view thereof. In this embodiment, an apparatus for aligning and bonding the light emitting element 20 that is a functional device that is the first object to be bonded and the substrate 22 that is the second object to be bonded is taken as an example. The bonding surface of the light emitting element 20 has a metal electrode made of gold as an electrode, and the metal electrode as an electrode is disposed on the bonding surface of the substrate 22 at a position facing the light emitting element side metal electrode. The light emitting element side metal electrode and the substrate side metal electrode are joined by heating after aligning the positions of the light emitting point 41 and the optical fiber 46.

  Subsequently, the bonding apparatus according to the present embodiment will be described in detail focusing on differences from the above-described embodiment. The joining apparatus is roughly composed of a joining mechanism 27 including a vertical drive mechanism 25 and a head unit 26, a mounting mechanism 28 including a stage 10 and a stage table 12, a position recognition unit 29, a transport unit 30, and a control device 31. The vertical drive mechanism 25 moves the head portion 26 up and down while being guided by the vertical guide 3 by the vertical drive motor 1 and the bolt / nut mechanism 2. The head portion 26 is guided in the vertical direction by the head escape guide 5, cancels its own weight, and detects the applied pressure while being pulled by the head weight counter 4 for pushing against the applied pressure detecting device 32. 32 and the vertical drive mechanism are grounded. The head unit 26 includes a chip holding tool 8 and a tip tool 9 that hold the light emitting element 20 by suction, a head side alignment table 7 that performs position correction with a translation axis of translation and rotation, and a head holding unit 6 that supports them. It is configured. A heating heater is embedded in the chip holding tool. The mounting mechanism 28 includes a stage 10 that holds the substrate 22 by suction, and a stage table 12 that has a moving axis for parallel movement and rotational movement for aligning the position of the light emitting element and the substrate. A stage heater 11 is built in the stage 10. The joining mechanism is coupled to the frame 34 and is connected to the gantry 35 around the center of pressure by the four support columns 13. The position recognition unit 29 is inserted between the opposed light emitting elements and the substrate so that the upper and lower mark recognition means 14 and the upper and lower mark recognition means 14 recognize the alignment marks for position recognition of the upper and lower light emitting elements and the substrate respectively. It comprises a recognition means moving table 15 that moves up and down. Further, the light emitting point recognizing means 33 is provided at the tip of the upper and lower mark recognizing means 14, and the position of the light emitting point can be measured by moving to an arbitrary position by the recognition means moving table 15.

  In addition, when the optical fiber is embedded in the substrate and the other end is exposed to the outside, the maximum point that becomes a light emitting point can be detected without using the light emitting point recognizing means by directly inputting the other end to the photometer. The transport unit 30 includes a substrate transport device 16 that transports the substrate 22, a substrate transport conveyor 17, a light emitting element (chip) supply device 18 that transports the light emitting elements 20, and a light emitting element (chip) tray 19. The control unit 31 includes overall control of the apparatus and an operation unit. Particularly in the pressure control, the torque of the vertical drive motor 1 is controlled by a signal from the pressure detection means 32 to control the pressure related to the joining.

  Next, a series of operations will be described. The light emitting element 20 is supplied from the light emitting element tray 19 to the light emitting element holding tool 8 by the light emitting element supply device 18 and is sucked and held. The substrate 22 is supplied from the substrate transfer conveyor 17 to the stage 10 by the substrate transfer device 16 and held by suction. The upper / lower mark recognition means 14 is inserted by the recognition means moving table 15 between the light emitting element 20 and the substrate 22 whose holding surfaces are opposed to each other, and the alignment marks for alignment between the opposing light emitting element 20 and the substrate 22 are recognized. The position is recognized by means 14. With the light emitting element 20 as a reference, the position of the substrate 22 is aligned and moved in the translational and rotational movement directions by the stage table 12. Although the position may be corrected on the light emitting element side with the head side alignment table, in this embodiment, the head side alignment table is assumed to be an alignment table composed of a piezo with a fine stroke and a fine stroke. To do.

  The upper and lower mark recognizing means 14 is retracted by the recognizing means moving table 15 in a state where both the joining positions are aligned. Next, the head portion 26 is lowered by the vertical drive mechanism 25, and the light emitting element 20 and the substrate 22 are grounded. The position of the head portion 26 in the height direction is detected by the head height detecting means 24. The timing for grounding the light emitting element 20 and the substrate 22 is detected by the pressure detection means 32, and the vertical drive motor is switched from position control to torque control. The head height is monitored by the head height detection means 24 even during pressurization switched to torque control, and the position in the height direction can also be controlled.

  In a state where a constant pressing force is applied between the objects to be joined by the torque of the motor, the probe 42 is brought into contact with the electrode 43 on the upper surface of the light emitting element, and the probe 44 is brought into contact with the electrode 45 on the upper surface of the substrate. The probe 42 is preferably attached from the head and moves up and down simultaneously with the head. Further, a part of the surface of the holding tool can be plated with metal to form a probe. Probes are brought into contact with both electrodes to cause the light emitting element to emit light and function. If the PLC substrate has a V-shaped groove and an optical fiber is held, a photometer is set at the other end of the optical fiber to find the light emitting element position where the maximum luminous intensity is obtained. Since the position between the light emitting element and the substrate has already been corrected by the alignment mark, the positional accuracy is within several μm.

  From that state, alignment of the light emitting point and the optical fiber is performed with submicron accuracy. In the alignment method, the light emitting element is caused to emit light, the light intensity from the optical fiber is measured, the light amount is measured while slightly changing the position of the light emitting element while moving the head up and down, and the maximum point is obtained. The position of the light emitting element is determined at the maximum point, and bonding is performed by low-temperature heating at 180 ° C. or lower. As a result, they are joined both positionally and electrically. As a method for recognizing the light emission point, the position where the light quantity is maximized is generally regarded as the light emission point. However, it is preferable to recognize the light emission point including the surrounding gray state even if it is not the maximum value. Since the position of the light emitting point is determined by the thickness from the lower part of the light emitting element to the light emitting point in the height direction, it can be maintained with high precision if attention is paid during manufacture. However, since the horizontal direction depends on the mounting accuracy, even if an alignment mark is used, it is difficult to mount with high accuracy including the positional error between the alignment mark and the light emitting point, and this embodiment is effective.

  When the optical fiber is not attached, the outer shape of the PLC substrate or the reference mark is recognized by the article recognition means. The article recognition means may be the upper / lower mark recognition means 14, the light emitting point recognition means, or any means. In addition, when the substrate mark is on a plane perpendicular to the light emitting direction, for example, an optical path conversion unit made of a prism may be provided on the tip tool side or the stage side. Further, when the mark is on the opposite surface, it can be recognized by recognizing the alignment mark 23 made of metal through the object to be bonded through the object recognition means using IR light.

  First, the V-groove position of the PLC substrate is recognized, and the position that becomes the center of the optical fiber is recognized. Next, the light emitting point is input to the matrix image sensor in the light emitting point recognizing means, and the input value is detected, and light emission is performed so that the matrix image sensor position where the maximum value is reached is the target matrix image sensor position which is the center of the optical fiber. Adjust the element position. Further, the light emitting point may be adjusted to the center position by moving the matrix imaging position to a target position. The light emitting point recognizing means 33 is moved as required by the recognizing means moving table 15 for PLC external position recognition and light emitting point recognition. After the position of the light emitting element is determined, the light emitting elements are bonded by low-temperature heating at 180 ° C. or lower.

  If the mark on the object to be bonded is in the same direction as the light emission direction, the optical system of the light emitting point recognition means recognizes the mark or the outer shape on the object to be bonded, This is preferable because the position where the light emission point is to be obtained can be easily understood and a change with the passage of time due to a relative position error or thermal expansion due to the individual recognition means does not occur. Also, as shown in FIG. 17, at least one object to be joined is held by a tool having an optical path changing means composed of a prism or a mirror, and the object and the light emitting point are recognized from the side by the same recognition means. Can be measured with higher accuracy.

  In addition, the light emitting point recognizing unit and the bonded object recognizing unit are separate matrix imaging devices, for example, when the magnification of the optical system is different. In that case, if the relative position between the individual matrix imaging elements is not known, it is not possible to know where the light emitting point should be brought even if the object mark is recognized. Therefore, the relative positional relationship can be calibrated if both are recognized using a reference jig in which the relative positions of the light emitting point and the object recognition mark are determined in advance. By doing so, it is possible to recognize even light emitting points and objects to be joined that have different sizes.

  After the bonding is completed, the adsorption of the light emitting element 20 is released, and remains on the stage with the light emitting element 20 mounted on the substrate 22 side. This is again discharged to the substrate transfer conveyor 17 by the substrate transfer device 16 and the series of operations is completed.

  Moreover, it can join also by giving ultrasonic vibration instead of heat joining. This method can be bonded at a low temperature and can be bonded at a room temperature, so that metal bonding can be performed in a solid phase without being affected by thermal expansion. It can be mounted with high accuracy without displacement by suppressing the amplitude to a small level and applying vibration after applying pressure.

  Next, a difference from the above will be described with respect to a modified example in which a surface light emitting type light emitting element is used. FIG. 14 is an explanatory view of a method of aligning and bonding between a surface light emitting element as a modification and a substrate in which an optical fiber is embedded. In the case of a surface light emitting element, the alignment marks for positioning the light emitting element 20 and the substrate 22 facing each other are recognized by the upper and lower mark recognizing means 14, the positions of the light emitting element 20 and the substrate 22 are aligned, and a constant pressure is applied. The probe is brought into contact with both electrodes on the substrate in a state where it is applied between the electrodes serving as both joint surfaces, and the light emitting element is caused to emit light and function. The light emitting point recognizing means 33 moves to the end of the optical fiber embedded in the substrate 22 by the recognizing means moving table 15 and measures the light intensity. Since the position between the light emitting element and the substrate has already been corrected by the alignment mark, the positional accuracy is within several μm. From that state, alignment of the light emitting point and the optical fiber is performed with submicron accuracy.

  In the alignment method, the light emitting element is caused to emit light, the light intensity from the optical fiber is measured, the light amount is measured while slightly changing the position of the light emitting element while moving the head up and down, and the maximum point is obtained. The position of the light emitting element is determined at the maximum point, and bonding is performed by low-temperature heating at 180 ° C. or lower. As a result, they are joined both positionally and electrically. As a method for recognizing the light emission point, the position where the light quantity is maximized is generally regarded as the light emission point. However, it is preferable to recognize the light emission point including the surrounding gray state even if it is not the maximum value. Since the position of the light emitting point is determined by the thickness from the lower part of the light emitting element to the light emitting point in the height direction, it can be maintained with high precision if attention is paid during manufacture. However, since the horizontal direction depends on the mounting accuracy, even if an alignment mark is used, it is difficult to mount with high accuracy including the positional error between the alignment mark and the light emitting point, and this method is effective.

  In the case of a submount substrate in which the optical fiber is not embedded in the substrate and the optical path hole is opened, the outer shape or the reference mark of the submount substrate is recognized by the bonded object recognition means. Further, the article recognition means may be the upper / lower mark recognition means 14, the light emitting point recognition means, or any means. Further, when the substrate mark is on the vertical plane, for example, an optical path changing means made of a prism may be provided on the tip tool side or the stage side. Further, when the mark is on the opposite surface, it can be recognized by recognizing the alignment mark 23 made of metal through the object to be bonded through IR (infrared) light.

  If the optical path hole position or submount position of the submount is recognized from the outline or mark in advance and the position where the light emitting point should be recognized is recognized, the light emitting point is directly input to the matrix image sensor, and the input value is detected. This can be achieved by adjusting the light emitting element position so that the matrix image sensor position having the maximum value becomes the target matrix image sensor position. Further, the light emitting point may be adjusted to the center position by moving the matrix imaging position to a target position. As a method of recognizing the light emission point by the matrix imaging means, the maximum image sensor position is generally regarded as the light emission point. It is preferable to recognize. If the mark on the object to be bonded is in the same direction as the light emission direction, the optical system of the light emitting point recognition means recognizes the mark or the outer shape on the object to be bonded, This is preferable because the position where the light emission point is to be obtained can be easily understood and a change with the passage of time due to a relative position error or thermal expansion due to the individual recognition means does not occur.

  Further, at least one of the objects to be joined is held by a tool having an optical path changing means such as a prism or a mirror as shown in FIG. 18, and the object to be joined and the light emitting point are recognized from the side by the same recognition means. Therefore, it is possible to measure with higher accuracy. Further, the light emitting point recognizing means 33 is moved as required by the recognizing means moving table 15 for the substrate outer position recognition and the light emitting point recognition. After the light emitting point bonding is completed, the adsorption of the light emitting element 20 is released and remains on the stage with the light emitting element 20 mounted on the substrate 22 side. This is again discharged to the substrate transfer conveyor 17 by the substrate transfer device 16 and the series of operations is completed.

  Further, by providing an ultrasonic transmitter and a horn instead of the light emitting element holding tool 8 and / or the tip tool 9, by applying ultrasonic vibration instead of heat bonding at the time of the bonding, the metal can be more easily solid-phased. Can be joined. In this case, since bonding can be performed at a low temperature and also at room temperature, metal bonding can be performed in a solid phase without being affected by thermal expansion. It can be mounted with high accuracy without displacement by suppressing the amplitude to a small level and applying vibration after applying pressure.

  In the fifth embodiment, the example of the light emitting element and the substrate has been described. However, the object to be bonded is included in the present invention even if it is a functional device other than the light emitting element that requires position adjustment.

<Sixth Embodiment>
Next, a sixth embodiment of the present invention will be described in detail. The point that this embodiment is greatly different from the first to fifth embodiments is that the above-described leveling is performed on the joint before joining the objects to be joined (see FIGS. 8 to 11). Hereinafter, a configuration unique to the present embodiment will be described in detail.

  In order to carry out room-temperature bonding temperature while maintaining a solid phase in the atmosphere, the bonding surface (bonding part) is etched in advance by several nanometers with Ar plasma (energy wave) in a vacuum to remove deposits. In the case of bonding in the air after cleaning, an adhering layer is formed on the bonding surface, so even if they are brought into contact, they are not bonded as they are. However, since the deposit layer is also thin immediately after cleaning, a new surface appears by pressure and bonded. As shown in FIG. 7, even in the air, after dry cleaning, if it is not left, it can be joined at room temperature by applying pressure. This is considered to be a degree to which a thin adhesion layer is formed on the bonding surface, but is torn by pressurization.

  Moreover, in this embodiment, since leveling is applied to the joint portion, a pressure of 300 MPa is necessary for joining when leveling is not performed, whereas a sufficient bonding strength is obtained with a pressure of 150 MPa. I was able to get it. This is considered to be because the pressures required to crush the rough portions of the joints are different in order to bring the joints into contact with each other due to the height variation of the bumps 20a and 22a and the surface roughness. It is done. A normal bump without leveling had a height variation of 2 μm and a surface roughness of 200 nm. However, after leveling, the bump height variation and the surface roughness were both 50 nm or less. Therefore, it is considered that the bonding load could be reduced. The leveling means that the height and the surface roughness are uniformly corrected by pressing the bump against the reference table 40 having flatness as shown in FIG. The chips leveled in advance may be aligned, or may be bonded to the substrate after being leveled by a bonding apparatus before bonding.

  Further, in order to crush and join the joint, the joining metal must have low hardness. In the present embodiment, similarly to the above-described embodiment, a metal joint having a hardness of 200 Hv or less is employed, and particularly when gold or copper is employed, the metal joint can be firmly joined. Moreover, it was possible to join at a pressure of 150 MPa or less when leveling. In particular, gold is an effective metal because it has low hardness and does not oxidize in the air.

  In addition, flip chip bonding of a semiconductor chip having a large number of electrode portions to be metal bumps is desired to have a heat effect on the semiconductor and to be mounted with high accuracy within a few μm from a fine pitch electrode. There is a high demand for joining at low temperatures. Therefore, the configuration in the present embodiment is particularly effective.

  The semiconductor chip may be in any form such as a chip or a wafer. In addition, the metal bumps may have a plurality of independent shapes, or may have a connected shape confined in a certain region. Further, the entire surface may be a bonding surface.

  In the sixth embodiment, the example of the chip and the substrate has been described, but the object to be bonded may be a material other than a semiconductor.

<Seventh embodiment>
The seventh embodiment of the present invention will be described in detail below. FIG. 19 shows a seventh embodiment of the joining apparatus according to the present invention. In the seventh embodiment, an apparatus for bonding a chip 20 made of a semiconductor as a first object to be bonded and a substrate 22 made of a wafer as a second object to be bonded is taken as an example. The bonding surface of the chip 20 has a plurality of bumps 20a which are metal electrodes made of gold as an electrode, and the metal pad 22a which is an electrode is arranged on the bonding surface of the substrate 22 at a position facing the chip-side metal electrode. Yes. The chip-side metal electrode and the substrate-side metal electrode are joined by pressurization after the treatment with the energy wave.

  The joining apparatus is roughly composed of a joining mechanism 27 including a vertical drive mechanism 25 and a head unit 26, a mounting mechanism 28 including a stage 10 and a stage table 12, a position recognition unit 29, a transport unit 30, and a control device 24. The vertical drive mechanism 25 moves the head portion 26 up and down while being guided by the vertical guide 3 by the vertical drive motor 1 and the bolt / nut mechanism 2. The head portion 26 is guided in the vertical direction by the head escape guide 5, cancels its own weight, detects the pressing force while being pulled by the head own weight counter 4 to be pressed against the pressing force detecting means 32, and applies the pressing force. The detection means 32 and the vertical drive mechanism are grounded.

  The head unit 26 includes a chip holding tool 8 that sucks and holds the chip 20 and a tip tool 9, a head-side alignment table 7 that performs position correction with a translation axis of translational movement and rotational movement, and a head holding part 6 that supports them. Has been. A heating heater is embedded in the chip holding tool. The mounting mechanism 28 includes a stage 10 that holds the substrate 22 by suction, and a stage table 12 that has a movement axis for parallel movement and rotational movement for aligning the position of the chip and the substrate. A stage heater 11 is built in the stage 10. The joining mechanism is coupled to the frame 34 and is connected to the gantry 35 around the center of pressure by the four support columns 13. The position recognizing unit 29 is inserted between the opposed chip and the substrate, and the upper and lower mark recognizing means 14 and the upper and lower mark recognizing means 14 for recognizing the alignment marks for recognizing the positions of the upper and lower chips and the substrate are arranged horizontally and / or. It comprises a recognition means moving table 15 that moves up and down.

  The transfer unit 30 includes a substrate transfer device 16 that transfers the substrate 22, a wafer cassette 243, a chip supply device 18 that transfers the chips 20, and a chip tray 19. Further, in order to perform cleaning and bonding continuously, the cleaning machine 241 is connected to the bonding apparatus by a conveying means, and the chip tray and the wafer are carried into the cleaning machine and taken out as needed. The chip tray 19 is supplied and stored from the chip tray cassette 242. The wafer 22 is supplied and stored from the wafer cassette 243. The control unit 31 includes overall control of the apparatus and an operation unit. Particularly in the pressure control, the torque of the vertical drive motor 1 is controlled by a signal from the pressure detection means 32 to control the pressure related to the joining.

  Next, a series of operations will be described. The cleaned chip 20 is supplied from the chip tray 19 to the chip holding tool 8 by the chip supply device 18 and is sucked and held. The substrate 22 made of the cleaned wafer is supplied to the stage 10 by the substrate transfer device 16 and sucked and held. The upper and lower mark recognition means 14 is inserted by the recognition means moving table 15 between the chip 20 and the substrate 22 whose holding surfaces are opposed to each other, and the alignment marks for alignment between the chip 20 and the substrate 22 facing each other are placed on the upper and lower mark recognition means 14. To recognize the position. With the chip 20 as a reference, the position of the substrate 22 is aligned and moved in the translational and rotational movement directions by the stage table 12. During alignment, the position may be corrected with the stage table 12 and the head side alignment table, or the position may be corrected with only the head side alignment table. Moreover, the structure of only one of the tables may be used.

  The upper and lower mark recognizing means 14 is retracted by the recognizing means moving table 15 in a state where both the joining positions are aligned. Next, the head portion 26 is lowered by the vertical drive mechanism 25, and the chip 20 and the substrate 22 are grounded. The position of the head portion 26 in the height direction is detected by the head height detecting means 24. The contact timing of the chip 20 and the substrate 22 is detected by the pressure detection means 32, and the vertical drive motor is switched from position control to torque control. The head height is monitored by the head height detection means 24 even during pressurization switched to torque control, and the position in the height direction can also be controlled. After the bonding is completed, the suction of the chip 20 is released and remains on the stage with the chip 20 mounted on the substrate 22 side. By continuously bonding the chips onto a substrate made of a wafer, the mounting is completed. This is again discharged to the wafer cassette 243 by the substrate transfer device 16 and the series of operations is completed.

  In the case where a plurality of chips are continuously bonded on one wafer, several hours pass if the number of chips is large. When bonding at room temperature in the air after dry cleaning, bonding to the bonding surface will increase if bonding is not performed within about one hour, making bonding impossible. Therefore, it is preferable to dry-clean (surface activation treatment) with reduced-pressure plasma (energy wave) again within 1 hour, preferably within 30 minutes. For this reason, the cleaning machine 241 is docked with the bonding apparatus, and when a certain time elapses during chip bonding to the wafer, the wafer is once transported from the stage to the cleaning machine and re-cleaned. After cleaning, the wafer is set on the stage again and chip bonding is started. By doing so, even in a wafer to which a large number of chips are bonded, the chips can be bonded continuously at room temperature in the atmosphere.

<Eighth Embodiment>
The eighth embodiment that best represents the features of the present invention will be described in detail below. First, the object to be bonded in this embodiment will be described in detail with reference to FIG. As shown in FIG. 24, in this embodiment, a device 829 and a lid 830 are joined as an object to be joined. On the bonding surface of the device 829, gold plating 831 is formed as a bonding portion with a thickness of 1 μm or more on the outline of a rectangular frame shape. A gold thin film 832 is formed on the joint surface of the lid 830 by sputtering or flash plating. Note that the pressure film plating 831 and the thin film 832 side may be formed in reverse. FIG. 24 shows a chip state, but as shown in FIG. 25, bonding on the wafer before dicing is most efficient.

  FIG. 20 shows a wafer bonding apparatus according to the eighth embodiment of the present invention. In this embodiment, the chamber is closed in a state where the wafer as the device to be bonded is held on the upper side and the wafer as the device is held vertically opposite to the lower side, etched with Ar plasma in vacuum, and then bonded to both The objects are brought into contact with each other and pressed to join them. In some cases, it is a device that heats at a low temperature within 180 ° C. to increase the strength. The apparatus has a configuration in which an upper wafer 807 (lid 830) is held, a head unit that performs elevation control and pressure control by a Z-axis 801, a lower wafer 808 (device 829), and a wafer alignment stage depending on circumstances. Divided into parts.

  A pressure detecting means is incorporated in the Z-axis 801, and pressure control is performed by feeding back to the torque control of the Z-axis servomotor. Separately, the chamber wall 803 that can be moved up and down by the actuator is lowered, vacuumed while being grounded to the chamber table 810 via the fixed packing 805, plasma treatment is performed by introducing a reactive gas, vacuuming is performed, and sealing is performed with a sealing gas In this case, the gas is replaced with the sealed gas, and the head portion is lowered so as to contact and pressurize both wafers to join them. The chamber wall 803 is sealed with an O-ring so as to be movable up and down, but it may be received at the thinned shaft or on the outer periphery of the piston. In some cases, the upper electrode 806 and the lower electrode 809 are also provided with a heater, and can be heated at the time of bonding.

  The operation will be described in order as shown in FIG. 21. The upper wafer 807 is held by the upper electrode (energy wave irradiation means) 806 with the chamber wall 803 raised as shown in FIG. The holding method includes a mechanical chucking method, but an electrostatic chuck method is desirable. Subsequently, the lower wafer 808 is held by the lower electrode (energy wave irradiation means) 809. Subsequently, the chamber wall 803 is lowered as shown in (b), and the chamber base 810 is grounded via the fixed packing 805. Since the chamber wall 803 is blocked from the atmosphere by the sliding packing 804, the exhaust valve 814 is opened with the suction valve 813 closed, and the vacuum level is increased by the vacuum pump 815, thereby increasing the degree of vacuum in the chamber. it can.

Next, as shown in FIG. 21C, the chamber is filled with a reaction gas composed of Ar. The vacuum pump 815 can be filled with the reaction gas while maintaining a certain degree of vacuum by controlling the discharge amount of the discharge valve 814 and the gas intake amount of the suction valve 813 while operating. As shown in (d) and (e), in this embodiment, first, Ar gas is filled, and a voltage for generating plasma by an alternating power source is applied to the lower electrode 809 with a degree of vacuum of about 10 ⁻² Torr. Plasma is generated, and the surface of the lower wafer 808 is etched with Ar plasma to remove an oxide layer and an adhering layer made of an organic substance adhering to the bonded portion, and then cleaned. Subsequently, by applying a voltage from the same alternating power source to the upper electrode 806, the upper wafer is etched and cleaned in the same manner as the lower wafer 808 by Ar plasma. Next, the chamber is evacuated as shown in FIG. In some cases, vacuuming is performed while heating both electrodes to about 100 ° C., whereby Ar adhering to the surface or being driven into the member is discharged. Thereafter, in the case of sealing with a sealing gas, the sealing gas is replaced.

  Subsequently, as shown in FIG. 21 (f), the piston-type head 802 is lowered by the Z-axis 801 while the chamber wall 803 and the Z-axis 801 are in contact with the sliding packing 4 in a vacuum or an enclosed gas. At this time, after the wafer has been surface activated by plasma, the suspended matter in the deposit layer removed by etching may reattach to the joint. However, both wafers are brought into contact with each other in a vacuum or in an encapsulated gas, and the wafers are bonded by pressing the adhesive layer that has been reattached to the bonded portion. The space formed is sealed in a predetermined atmosphere. The inside of the chamber is shielded from the external atmosphere by a sliding packing 804 between the chamber wall 803 and the Z-axis 801, and the piston-type head portion can be lowered while being held in a vacuum or an enclosed gas. In some cases, the strength is increased by simultaneously heating to about 180 ° C. with heaters charged in both electrodes. Thereafter, as shown in (g), air is supplied into the chamber and the pressure is returned to atmospheric pressure, the head portion is raised, and both bonded wafers are taken out. A method of switching between two gases of Ar and the atmosphere or nitrogen in one chamber can select and supply Ar and the atmosphere gas by the gas switching valve 816. First, after selecting and filling Ar, the suction valve 813 is closed, the inside of the chamber is evacuated, and Ar is discharged. Then, the gas switching valve 816 is switched to atmospheric gas, the suction valve 813 is opened, and the inside of the chamber is opened to the atmosphere. Can be filled and released to the atmosphere when opening the chamber.

  In some cases, when the objects to be bonded are bonded, the positions of the device and the lid are aligned and then bonded. FIG. 22 shows a method of alignment before evacuation. An upper mark 823 for alignment is attached to the upper wafer 807 at two places, and a lower mark 824 for alignment is attached to the lower wafer 808 at two similar positions. A two-field recognition means 825 is inserted between both wafers, and the upper and lower mark positions are read by the recognition means. The two-field recognizing means 825 branches the upper and lower mark images by the prism 826 and separates them into an upper mark recognizing means 827 and a lower mark recognizing means 828 and reads them. The two-field recognition means 825 is moved by a table having the XY axes and, in some cases, the Z axis, and can read a mark at an arbitrary position. Thereafter, the position of the lower wafer 808 is corrected and moved to the position of the upper wafer 807 by the alignment table 820. After the movement, it is also possible to insert the two-field recognition means 825 again and repeat the correction to improve the accuracy.

  FIG. 23 shows a method capable of alignment even after joining after evacuation. An upper mark 823 for alignment is attached to the upper wafer 807 at two places, and a lower mark 824 for alignment is attached to the lower wafer 808 at two places. The top and bottom marks are shaped so that they can be recognized in the same field of view even if they overlap. Both wafers after the plasma treatment are brought close to each other, pass through the mark reading transmission part 819 and the glass window 821, pass through the lower wafer by the IR recognition means 822, and simultaneously recognize the upper and lower alignment marks attached with metal. Read. If the depth of focus does not match, the IR recognition unit 822 may be moved up and down for reading. The IR recognizing means 822 is moved by a table having an XY axis and possibly a Z axis, and the position of the lower wafer 808 is corrected and moved to the position of the upper wafer 807 by an arbitrary 820. After the movement, it is possible to repeat the correction by the IR recognizing means 22 again to increase the accuracy.

  As described above, according to this embodiment, even if the suspended matter of the deposit layer removed by etching after the surface activation treatment of the wafer by plasma is reattached to the joint, the reattached deposit layer When the wafers are bonded by bonding the wafers together, the space formed by the bonding portion between the bonding surfaces surrounded by the contour can be sealed in a predetermined atmosphere.

  In addition, since the sealing gas is not corroded even if it is not an inert gas by using gold | metal | money as a joining part, it has no influence on joining. Therefore, gas other than inert gas can be applied in this embodiment.

  Etching with Ar plasma is preferable in terms of efficiency, but etching may be performed with other gases such as nitrogen and oxygen.

  In addition, it is preferable in terms of efficiency to clean the wafer held on the electrode surface to which the alternating power source is connected as a method of plasma processing (energy wave processing, surface activation processing) of the object to be bonded, but the uniformity and damage reduction. Then, the electrode may be installed in a place other than the wafer holding position, and the wafer may be cleaned (surface activation treatment).

  Further, in the configuration in which the mark is read by the IR recognizing means, the path of the IR light source in the space between the mark reading transmission portion 819, the glass window 821, and the alignment table is not limited to the space or glass, but is a material that transmits IR light. It only has to be configured. Further, not only the reflected light but also a light source on the opposite side of the IR recognition means may be used as the transmitted light.

  Further, an elastic material may be provided on the surface of at least one object holding means (head or stage), and both objects to be bonded may be pressed via the elastic material when the objects to be bonded are bonded. With such a configuration, the parallelism between the objects to be joined can be made uniform. Moreover, if it is a thin to-be-joined object, flatness can also be made equal.

  Further, the object holding means is held on the stage and / or the head by a spherical bearing, and the objects to be bonded are brought into contact with each other during or before bonding the objects to be bonded, so that at least one of the objects to be bonded is inclined. You may make it the structure which can be match | combined. With such a structure, it is possible to join with parallelism (see FIG. 29).

  In addition, the bonding apparatus according to the present embodiment is configured to be able to perform a batch process from the surface activation process (cleaning) of the wafer (bonded object) to the bonding of the bonded object. The surface activation device that performs the treatment and the bonding device that is bonded may be separated.

  With such a configuration, after the wafer surface activation treatment, in particular, when the alignment between the wafers is performed in the air, or when the wafers are transferred to the bonding apparatus through the air, an oxide film is formed on the bonded portion. And deposits such as organic matter tend to reattach. However, as described above, the wafers can be bonded to each other by pressurizing and pressing the reattached adherent layer.

<Ninth Embodiment>
A ninth embodiment of the present invention will be described in detail with reference to FIG. In this embodiment, the chamber is closed in a state where the wafer as the object to be bonded is held facing up and down, and after being treated with Ar plasma and oxygen plasma in a vacuum, it is bonded, and in some cases, the strength is increased by heating. It is. The apparatus configuration is divided into a head unit that holds the upper wafer 537 and performs the elevation control and pressurization control by the Z axis 531, and a stage unit that holds the lower wafer 538 and in some cases aligns the wafer. A pressure detecting means is incorporated in the Z-axis 531, and the pressure control is performed by feeding back to the torque control of the Z-axis servomotor. Separately, the chamber wall 533 that can be moved up and down by an actuator is lowered, vacuumed in a state where the chamber wall 533 is grounded via a fixed packing 535, and plasma treatment (surface activation treatment) is performed by introducing a reactive gas, Is lowered to join both wafers.

  In some cases, the upper electrode 536 and the lower electrode 539 are also provided with a heater, and can be heated at the time of bonding. Thereafter, air is supplied into the chamber and the pressure is returned to atmospheric pressure, the head portion is raised, and both bonded wafers are taken out. In some cases, bonding may be performed after aligning the positions of both wafers. In the case of alignment in the atmosphere, an optical system with two upper and lower visual fields is inserted between the objects to be bonded, and the head or stage side is corrected and moved in the horizontal and rotational directions. When aligning in a vacuum, a part of the stage is made of a transparent material from the bottom and the alignment mark made of metal is read while passing through both objects to be bonded by an IR light source, and the head or stage side is moved in the horizontal and rotational directions for correction. Just do it.

  In addition, the lower electrode (bonded object holding means) 539 is held by a copying mechanism (spherical bearing) 550, and the wafers are contacted and pressed during or before bonding the wafers, so that the upper wafer 537 side is tilted. Further, the inclination of the lower wafer 538 is matched. With such a configuration, the wafers (objects to be joined) can be joined with their parallelism being aligned (see FIG. 29). The copying mechanism 550 has a lock mechanism for selecting lock / free, and may be configured to be free only when copying in a normally locked state. In addition, once the parallelism is aligned, the copying mechanism 550 is locked, and after maintaining the state, plasma processing (energy wave processing) is performed, and the wafers can be aligned and bonded together. Therefore, the wafers can be joined without any positional deviation.

<Tenth Embodiment>
A tenth embodiment of the present invention will be described in detail with reference to FIG. In this embodiment, after performing plasma cleaning (surface activation treatment) in a vacuum, the objects to be joined are joined in the atmosphere. At least one of the objects to be bonded is carried into a cleaning chamber, and the cleaned objects to be bonded are connected to each other by a transporting unit, and a subsequent bonding object is cleaned during bonding.

  Surface activation can be performed by individually subjecting objects to be bonded, whose bonding surfaces are made of gold or copper, to plasma treatment in advance in a vacuum chamber, and can be taken out into the atmosphere and bonded. By connecting the cleaned objects to be bonded to a bonded portion and cleaning the subsequent objects to be bonded during bonding, the cleaning time can be processed in parallel, so that the tact time can be increased.

  In addition, when the balance is not achieved one by one, it may be cleaned in a state where a plurality of trays are placed. Moreover, if it is a to-be-joined object on a continuous reel, what is necessary is just to carry out plasma processing by inserting | pinching through a packing in a chamber door. In the case of alignment before bonding, a recognition means 663 having two upper and lower visual fields may be inserted between the objects to be bonded, and the head or stage side may be corrected and moved in the horizontal and rotational directions. The recognizing means 663 with two upper and lower visual fields can be moved to an arbitrary position by the recognizing means moving table and position measurement is possible.

  The holding means for holding the object to be bonded in vacuum is preferably an electrostatic chuck method, but may be a mechanical chucking method. In addition, a method of mechanically chucking after first vacuum-sucking and adhering in the atmosphere is preferable because adhesion is improved.

<Eleventh embodiment>
Next, an eleventh embodiment of the present invention will be described in detail with reference to FIG. In this embodiment, the apparatus is exemplified as an apparatus for bonding an upper wafer as a first object to be bonded and a lower wafer as a second object to be bonded. First, the apparatus configuration will be described. A head 907 that holds the upper wafer and a stage 908 that holds the lower wafer are arranged in the vacuum chamber 911, and the head is a Z-axis lifting mechanism (vertical driving mechanism) 902 and a Z-axis that are connected to a torque-controlled lifting drive motor 901. An X-axis mechanism that rotates the lifting mechanism 902 and an XY alignment table 906 that moves the head unit in the XY horizontal direction include an X, Y, θ-direction alignment moving means and a Z-direction lifting means.

  By feeding back the applied pressure detected by the pressure detecting means 904 to the torque control type lifting drive motor 901, position control and pressure control can be performed while switching. Further, the pressure detecting means 904 can be used for detecting contact between objects to be joined. The XY alignment table 906 uses means that can be used even in a vacuum. However, since the Z and θ axis mechanisms are installed outside the vacuum chamber, the head portion and the outside are movably blocked by a bellows 905.

  The stage 908 can be slid by the slide moving means 929 between the joining position and the standby position. A high-precision guide and a linear scale for recognizing the position are attached to the slide moving means, and the stop position between the joining position and the standby position can be maintained with high precision. In addition, the moving means is built in the vacuum chamber, but it is possible to place cylinders, linear servo motors, etc. outside by disposing the moving means outside and connecting them with packed connecting rods. It is. Alternatively, a ball screw can be placed in a vacuum and a servo motor can be installed outside. The moving means may be any moving means.

  The head and stage to-be-bonded object holding means may be a mechanical chucking method, but is preferably provided with an electrostatic chuck. In addition to providing a heater for heating, it also serves as a plasma electrode (energy wave irradiation means), and has three functions of a holding means, a heating means, and a plasma generating means. As a decompression means, a vacuum pump 917 is connected to an exhaust pipe 915, and opening / closing and flow rate adjustment are performed by an exhaust valve 916 so that the degree of vacuum can be adjusted. On the intake side, an intake gas switching valve 920 is connected to an intake pipe 918, and opening / closing and flow rate adjustment are performed by an intake valve 919.

  As the suction gas, two kinds of plasma reaction gases can be connected, for example, Ar and oxygen can be connected. The other is connected to the atmosphere or nitrogen for release. The degree of vacuum and the reaction gas concentration can be adjusted to optimum values by adjusting the flow rate including opening and closing of the intake valve 919 and the exhaust valve 916. In addition, automatic feedback can be performed by installing a vacuum pressure sensor in the vacuum chamber.

  Alignment mark recognition means comprising an alignment optical system is disposed outside the vacuum chamber above the stage standby position and below the head. The number of recognition means should be at least one on the stage and head side. If a small object such as a chip is to be recognized, the shape of the alignment mark can also read the θ direction component and two marks within one field of view. Although it is possible to read sufficiently even with one recognition means by arranging, it is possible to read with high accuracy in the θ direction when two large ones such as wafers are arranged at both ends as in this embodiment. It is preferable because it is possible.

  Further, the recognition means may be provided with means that can move in the horizontal direction or the focal direction so that the alignment mark at an arbitrary position can be read. The recognition means is a camera with an optical lens made of, for example, visible light or IR (infrared) light. A window made of a material, for example, glass, that can be transmitted through the optical system of the recognition means is disposed in the vacuum chamber, and the alignment mark of the object to be bonded in the vacuum chamber is recognized through the window. For example, alignment marks are provided on the surfaces of the upper wafer and the lower wafer facing each other on the object to be bonded so that they can be recognized with high positional accuracy. The alignment mark preferably has a specific shape, but a part of a circuit pattern or the like provided on the wafer may be used. Further, when there is no mark, an outline such as an orientation flat can be used.

  The alignment marks on the upper and lower wafers are read at the stage standby position, the stage is moved to the bonding position, and the alignment is moved in the X, Y, and θ directions on the head side. In order to reflect the reading result of the standby position at the joining position, it is necessary to have an accuracy so that the relative movement distance vectors of the standby position of the stage and the joining position are repeatedly the same. For this reason, a guide having a high repeatability is used, and a linear scale that reads position recognition on both sides with high accuracy is arranged.

  If the linear scale is fed back to the moving means to improve the stopping position accuracy and the moving means is a simple cylinder or backlash like a bolt / nut mechanism, the linear scale should be Therefore, it is possible to easily achieve high accuracy by making corrections by taking into account when the head-side alignment moving means is moved. Also, when fine alignment is performed with high precision at the nano level, after performing rough positioning, visible light and IR combined recognition means are used for the head side recognition means with the upper wafer and the lower wafer brought close to about several μm. However, by providing a transmission hole or a transmission material at the position of the alignment mark on the stage, the alignment mark on both wafers can be simultaneously recognized through the stage from below, and alignment in the X, Y, and θ directions can be performed again. . When the recognition means has a movement means in the focal direction, it can be recognized separately in the upper and lower directions, but it is more preferable in terms of accuracy to make the recognition close and simultaneously recognize.

  When fine alignment is performed, accuracy can be improved by repetitive alignment. In addition, since the θ direction is affected by the runout, the accuracy is reduced to the nano level by performing alignment only in the XY direction after entering within a certain range. Can be improved. By using a sub-pixel algorithm as an image recognition means, it is possible to obtain recognition accuracy that is higher than the infrared resolution. In addition, if they are aligned close to each other, the amount of Z movement required during bonding is within a minimum of several μm, so that the backlash and inclination with respect to Z movement can be kept to a minimum, achieving highly accurate nano-level bonding accuracy. can do.

Next, the operation flow will be described with reference to FIG. First, as shown in (a), the upper wafer and the lower wafer are held on the stage and head with the front door of the vacuum chamber opened. This may be done manually, but may be automatically loaded from the cassette. Next, as shown in (b), the front door is closed and the vacuum chamber is depressurized. In order to remove impurities, the pressure is preferably reduced to 10 ⁻³ Torr or less. Subsequently, as shown in (c) and (d), for example, Ar, which is a plasma reaction gas, is supplied, and a plasma generation voltage is applied to the plasma electrode at a constant degree of vacuum of, for example, about 10 ⁻² Torr. generate.

The generated plasma ions collide toward the surface of the wafer held by the electrode to which the power source is connected, and surface deposits such as oxide films and organic layers are etched to activate the surface. Both wafers can be cleaned at the same time, but can also be cleaned alternately by switching one matching box. Further, it is preferable to reduce the pressure to 10 ⁻³ Torr or less in order to remove the reaction gas and the etched product after or during the cleaning. In order to remove Ar implanted into the bonding surface, heating can be used in combination at about 100 to 200 ° C.

  Subsequently, as shown in FIG. 32 (e), the alignment marks on the upper and lower wafers are read in vacuum by the recognition means on the head side and the stage side at the stage standby position to recognize the positions. Subsequently, as shown in (f), the stage slides to the joining position. The relative movement between the recognized standby position and the sliding joint position at this time is performed with high accuracy using a linear scale. When nano-level high accuracy is required, the process shown in 7 is added. After rough positioning, visible light and IR recognition means are used for the head side recognition means with the upper wafer and the lower wafer brought close to each other by several μm. , The alignment marks on both wafers are transmitted through the stage from the lower part and transmitted through the infrared rays to be simultaneously recognized, and can be aligned again in the X, Y, and θ directions. In this case, it is possible to improve accuracy by repeatedly aligning, and the θ direction is affected by the runout, so after entering within a certain range, the accuracy can be improved to the nano level by performing alignment only in the XY direction. .

  Subsequently, as shown in FIG. 32 (h), the head is lowered, both wafers are brought into contact with each other, and pressure is switched from position control to pressure control. In a state where the contact is detected by the pressure detection means and the height position is recognized, the value of the pressure detection means is fed back to the torque control type lifting drive motor to control the pressure so as to become the set pressure. Further, heating is applied at the time of joining as necessary. After contacting at normal temperature, heating can be performed while maintaining accuracy by raising the temperature. Subsequently, as shown in (i), the head side holding means is released and the head is raised. Subsequently, as shown in (j), the stage is returned to the standby position, and the inside of the vacuum chamber is released to the atmosphere. Subsequently, as shown in (k), the front and rear wafers are taken out by opening the front door. Although it may be manual, it is preferable to automatically unload the cassette.

  In addition, a metal electrode is disposed on the facing surface of at least one object to be bonded at the time of cleaning (treatment with energy waves), and a metal film made of metal constituting the electrode is formed on the bonding surface of the object to be bonded by sputtering. Thereafter, the objects to be joined can be joined together. Since the object can be moved and plasma can be generated in a state where the bonding surfaces of the objects to be bonded do not face each other, a metal to be sputtered is disposed on the opposite surface of the bonding surface (bonding portion). Is used as an electrode for plasma generation, the metal is sputtered onto the surface of the object to be joined (joint surface), and a metal thin film made of the metal is formed. Further, different metals can be used for sputtering on the head side and the stage side.

  Further, the plasma reaction gas can be cleaned individually using different gases for one object to be bonded and the other object to be bonded.

  Further, an elastic material may be disposed on the surface of at least one of the objects to be bonded, and both objects to be bonded may be pressurized via the elastic material when the objects to be bonded are bonded. With such a configuration, the parallelism between the objects to be joined can be made uniform. Moreover, if it is a thin to-be-joined object, flatness can also be made equal.

  Moreover, it is good also as a structure by which a to-be-joined object holding | maintenance means is hold | maintained at a stage and / or a head with a spherical bearing. With such a configuration, the objects to be bonded can be contact-pressed during bonding of the objects to be bonded or before bonding, so that the inclination of the other can be adjusted to at least one of the objects to be bonded. Therefore, it is possible to join with the parallelism of the objects to be joined.

  In addition, since the bonding surfaces of the objects to be bonded are surface-activated by plasma treatment, the heating temperature at the time of bonding between the objects to be bonded is 180 ° C. which is 183 ° C. or less which is the melting temperature of conventional tin-lead solder. Solid phase bonding can be performed as follows. Further, it is possible at 100 ° C. or lower, and it is possible at room temperature, which is preferable.

  In addition, since a three-dimensional structure can be obtained by bonding semiconductors by the above method, a semiconductor device with a higher degree of integration can be formed, which is preferable.

  In addition, when ultrasonic vibration is used at the time of joining, the head 907 is composed of a horn holding portion, a horn, and a vibrator, and the vibration caused by the vibrator is transmitted to the horn, and the horn holds the ultrasonic vibration. To communicate. The horn holding unit includes means for holding the horn and the vibrator so as not to kill the vibration. Since the transmissibility at this time is determined by the friction coefficient and pressure of the horn and the object to be joined, it is preferable to control the applied pressure in proportion to the joining area as the joining proceeds. In addition, when bonding a large area such as a wafer, it is impossible for the transverse vibration type ultrasonic head to vibrate laterally because the bonding area is large, but if it is a longitudinal vibration type ultrasonic head, Large area surface bonding is also possible. Although referred to as ultrasonic vibration, the vibration frequency does not have to be particularly in the ultrasonic region. Especially in the case of the longitudinal vibration type, the effect is sufficiently exhibited even at a low frequency.

  Moreover, although the wafer was raised as a to-be-joined object in the said embodiment, a chip | tip and a board | substrate may be sufficient. The object to be bonded is not limited to a wafer, a chip, and a substrate, and may be in any form.

  The holding means for the object to be joined is preferably an electrostatic chuck method, but may be a mechanical chucking method. In addition, a method of mechanically chucking after first vacuum-sucking and adhering in the atmosphere is preferable because adhesion is improved.

  In the above embodiment, the head side has the alignment moving means and the lifting shaft, and the stage side has the slide shaft. However, the alignment moving means, the lifting shaft, and the slide shaft can be combined in any way on the head side and the stage side. Good and may overlap. Further, even if the head and the stage are not arranged vertically, it does not depend on the arrangement direction such as left-right arrangement or diagonal.

  Also, when plasma cleaning is performed with the stage moved, the electric field environment is similar because the electrode shape of the head and the stage and the surrounding shape are similar. Therefore, the matching box for automatically adjusting the plasma power source can be switched to the head side and the stage side sequentially by switching the electrodes by one without using an individual one. By doing so, downsizing and cost reduction can be achieved.

<Others>
The present invention is not limited to the above-described embodiments, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the first embodiment, the process from the surface activation process (cleaning) of the object to be bonded to the bonding of the object to be bonded is performed as a batch process with the same apparatus. The activation process and the bonding process for bonding the objects to be bonded may be performed by different apparatuses.

  In the above embodiment, an elastic material may be disposed on the surface of at least one object holding means (head or stage), and both objects to be bonded may be pressurized via the elastic material when the objects to be bonded are bonded. Absent. With such a configuration, the parallelism between the objects to be joined can be made uniform. Moreover, if it is a thin to-be-joined object, flatness can also be made equal.

  In the above-described embodiment, the object holding means is held by the stage and / or the head with a spherical bearing, and at least one of the objects to be bonded is obtained by contacting and pressing the objects to be bonded at the time of bonding of the objects to be bonded or before bonding. It is also possible to adopt a structure in which the other inclination can be matched. With such a structure, it is possible to join with parallelism (see FIG. 29).

  Further, by providing an ultrasonic transmitter and a horn instead of the object holding tool, metal bonding can be more easily performed in a solid phase by applying ultrasonic vibration instead of heat bonding during the bonding. In this case, since bonding can be performed at a low temperature and also at room temperature, metal bonding can be performed in a solid phase without being affected by thermal expansion. It can be mounted with high accuracy without displacement by suppressing the amplitude to a small level and applying vibration after applying pressure.

  In addition, an ultrasonic vibration head including a horn, a horn holding portion, and a vibrator is provided, and ultrasonic vibration having an amplitude of 2 μm or less is applied to an object to be bonded at the time of bonding in the atmosphere, a load of 150 MPa or less, 180 ° C. A method and a bonding apparatus for metal bonding in a solid phase by the following heating may be used. When ultrasonic vibration is applied at the time of joining in the atmosphere, joining becomes easier. Since the surface has already been activated, the ultrasonic energy may be small, and an amplitude of 2 μm or less that can suppress damage and displacement is sufficient. Moreover, it is more preferable if it is 1 micrometer or less. Further, by applying ultrasonic waves, the bonding load can be lowered to 150 MPa or less, which is half or less. When gold metal protrusions are bonded, bonding cannot be performed unless they are crushed at a high pressure of about 300 MPa at room temperature. When this bump is on the surface of the semiconductor circuit, it is generally damaged depending on the circuit at 200 MPa or more. The experimental condition is that when a semiconductor chip using a gold bump with a 50 μm square, 20 μm height and 1 μm bump height variation to be a metal protrusion on the semiconductor chip is ultrasonically bonded onto a gold thin film substrate and at room temperature bonding In the case of normal temperature bonding, bonding was possible for the first time at 80 g / bump, but when ultrasonic waves were applied, bonding was possible with a load of 40 g / bump or more. Therefore, it can be seen that it is necessary to crush bumps of 1 μm or more as a bump crushing allowance. In the case where a bump having a height of 20 μm is formed by gold plating, it is necessary to crush the bumps of this degree because it is the limit to suppress the height variation to 1 μm.

The figure which shows the relationship between the hardness of a metal, and joining strength. The removal schematic diagram of the adhesion film by the unevenness | corrugation of a joining interface. The rotation schematic diagram of the crystal direction in the joining interface at the time of joining. The figure which shows the relationship between joining surface roughness and joining strength. The figure which shows the relationship between the head stop time at the time of joining, and joining strength. The figure which shows the relationship between the heating temperature at the time of the head stop at the time of joining, and joining strength. The figure which shows the relationship between the joining load by the presence or absence of leveling, and joining strength. The schematic diagram showing the roughness of the bump surface. The schematic diagram showing the variation in bump height. Schematic diagram of leveling. The schematic diagram showing joining of the chip | tip and a board | substrate after leveling. Explanatory drawing of the alignment method of a light emitting element. The side view of the alignment method to the optical fiber on PLC of a side light emitting element. The side view of the alignment method to the optical fiber embedding type | mold board | substrate of a side surface light emitting element. Issuing element alignment joining device. The schematic diagram showing diffusion of a gold film. The block recognition block diagram from the side by the optical path conversion means of a parallel light emitting element. The block recognition block diagram from the side by the optical path conversion means of a planar light emitting element. The figure which shows a joining apparatus. The figure which shows a joining apparatus. The figure which shows a joining process. The alignment block diagram in the air | atmosphere using 2 visual field recognition means. The alignment block diagram in the vacuum using IR recognition means. The block diagram of the chip level of a device. The wafer level block diagram of a device. RF plasma power supply diagram. Pulse wave plasma power supply diagram. Damage reduction method by pulse width. The figure which shows a joining apparatus. The figure which shows a washing | cleaning apparatus and a joining apparatus. The figure which shows a joining apparatus. The figure which shows a joining process.

Explanation of symbols

20 ... chip (bonded object)
20a ... Bump (joint)
22 ... Chip (object to be joined)
22a ... Bump (joint)
25 ... Vertical drive mechanism 26 ... Head part 28 ... Mounting mechanism (stage)
42, 44 ... Probe 531 ... Z-axis (vertical drive mechanism)
532 ... Piston type head (head)
539 ... Lower electrode (stage)
550 ... Copying mechanism (spherical bearing)

Claims (27)

In a joining method for joining objects to be joined having a joint made of metal,
After forming at least one of the joints in a contour shape and surface-activating both the joints with plasma, the joints are brought into contact with each other to pressurize them to reattach the organic matter or oxide film A bonding layer formed by piercing and bonding a deposit layer, and sealing a space formed by the bonding portion between the bonding surfaces of the objects to be bonded to the contour shape in a predetermined atmosphere. Method.   The bonding method according to claim 1, wherein the space is sealed in a vacuum atmosphere by bonding the objects to be bonded together in a vacuum.   The bonding method according to claim 1, wherein the space is sealed in the sealed gas atmosphere by bonding the objects to be bonded together in a sealed gas.   The joining method according to any one of claims 1 to 3, wherein the objects to be joined are joined in a solid phase under a low temperature heating of room temperature to 180 ° C or lower.   The joining method according to any one of claims 1 to 4, wherein a hardness of the joining portion is 20Hv to 200Hv.   The joining method according to claim 1, wherein the joining portion is gold. The joining portion of the article to be joined is formed by forming a gold film on the surface of a base material having a hardness of 200 Hv or less,
The bonding method according to claim 1, wherein the gold film is diffused in the base material after the objects to be bonded are bonded.   The object to be bonded is a semiconductor or a MEMS device including a plurality of metal bumps in which the bonding portion is formed by forming a gold film on a surface of the base material and the base material is copper. The joining method according to claim 7, wherein the gold film is diffused in the base material after joining the two.   The bonding method according to claim 6, wherein the gold or the gold film constituting the bonding portion of at least one of the objects to be bonded is gold plating having a thickness of 1 μm or more.   The bonding method according to claim 1, wherein the surface roughness Ry of the bonded portion of at least one of the bonded objects is 120 nm to 2 μm.   The joining method according to any one of claims 1 to 9, wherein, after leveling the joining portion of at least one of the objects to be joined, the joining portion of each of the objects to be joined is treated with the plasma and then joined.   The bonding method according to claim 11, wherein the leveling is performed before the objects to be bonded are bonded to each other by the objects to be bonded.   The bonding method according to claim 1, wherein the object to be bonded is a chip or a wafer made of a semiconductor or a MEMS device.   A device such as a semiconductor device or a MEMS device formed by the bonding method according to claim 1. In a joining apparatus for joining objects to be joined having a joint made of metal,
A head for holding one of the objects to be joined;
A stage for holding the other object to be joined;
A vertical drive mechanism capable of controlling the pressure of at least one of the head or the stage in a direction substantially perpendicular to the bonding surface of the workpiece;
After the at least one of the joints is formed in a contour shape, and both the joints are surface-activated by plasma, the adherend layer made of an organic substance or an oxide film is reattached to the joints. ,
The joints are brought into contact with each other and pressurized to press and join, and the space formed between the joint surfaces of the objects to be joined and surrounded by the contour is sealed in a predetermined atmosphere. The joining apparatus characterized by performing. In the vacuum chamber,
The head;
The stage;
The vertical drive mechanism,
The bonding apparatus according to claim 15, wherein the space is sealed in a vacuum atmosphere by bonding the objects to be bonded together in a vacuum. In the vacuum chamber,
The head;
The stage;
The vertical drive mechanism,
The bonding apparatus according to claim 15, wherein the space is sealed in the sealed gas atmosphere by replacing the inside of the decompression chamber with a sealed gas and bonding the objects to be bonded in the sealed gas.   The bonding apparatus according to any one of claims 15 to 17, wherein the objects to be bonded are bonded in a solid phase under low temperature heating of room temperature to 180 ° C or lower.   The joining device according to any one of claims 15 to 18, wherein the joined objects having a hardness of the joining portion of 20Hv to 200Hv are joined together.   The joining device according to any one of claims 15 to 19, wherein the joined parts are made of gold and are joined together. The joining portion of the article to be joined is formed by forming a gold film on the surface of a base material having a hardness of 200 Hv or less,
The bonding apparatus according to claim 15, wherein the gold film is diffused in the base material after bonding the objects to be bonded.   The object to be bonded is a semiconductor or MEMS device including a plurality of metal bumps in which the bonding portion is formed by forming the gold film on the surface of the base material, and the base material is copper. The bonding apparatus according to claim 21, wherein the gold film is diffused into the base material after bonding the two.   The bonding according to any one of claims 20 to 22, wherein the gold or the gold film constituting the bonding portion of at least one of the objects to be bonded bonds the objects to be bonded which are gold plating having a thickness of 1 µm or more. apparatus.   The joining apparatus according to any one of claims 15 to 23, wherein the joined objects whose surface roughness Ry of the joined part of at least one of the joined objects is 120 nm to 2 µm are joined together.   The joining apparatus according to any one of claims 15 to 23, wherein after leveling the joining portion of at least one of the objects to be joined, the joining portion of each of the objects to be joined is treated with the plasma and then joined.   The leveling is performed by bringing the objects to be bonded held opposite to the head and the stage into contact with each other, and then bonding the bonded portions of the objects to be bonded after being treated with the plasma. Item 26. A bonding apparatus according to Item 25.   27. The bonding apparatus according to claim 15, further comprising energy wave irradiation means for generating the plasma.

Images