JP2022034744A - Substrate bonding device - Google Patents

Abstract

To provide a substrate bonding device capable of reducing generation of voids and contamination, in a bonded substrate manufacturing device for bonding a bandgap semiconductor substrate and a handle substrate with each other.SOLUTION: A substrate bonding device that manufactures a bonded substrate by bonding a bandgap semiconductor substrate and a handle substrate with each other, comprises: a substrate holder that has a bonding chamber in which the bandgap semiconductor substrate and the handle substrate are bonded with each other, a first holder provided in the bonding chamber to hold any one of the bandgap semiconductor substrate and the handle substrate; and a second holder that holds the other of the bandgap semiconductor substrate and the handle substrate; an ultraviolet ray irradiation device that irradiates a bonding surface of at least one of the bandgap semiconductor substrate and the handle substrate held by the substrate holder with an ultraviolet ray; and a vacuum device that makes the inside of the bonding chamber vacuum.SELECTED DRAWING: Figure 1

Description

The present invention relates to a substrate bonding apparatus.

Silicon carbide is a compound semiconductor material composed of silicon and carbon. Silicon carbide has an insulation breakdown electric field strength 10 times that of silicon and a band gap 3 times that of silicon, and is excellent as a semiconductor material. Furthermore, since it is possible to control the p-type and n-type required for manufacturing devices in a wide range, it is expected as a material for power devices that exceeds the limit of silicon.

Further, since silicon carbide can obtain a high withstand voltage even with a thinner thickness, it is characterized in that a semiconductor having a small ON resistance and a low loss can be obtained by making it thin.

However, in the silicon carbide semiconductor, it is difficult to obtain a silicon carbide single crystal substrate having a large area as compared with the silicon semiconductor which has been widely used in the past, and the manufacturing process is complicated. For these reasons, silicon carbide semiconductors are difficult to mass-produce and expensive as compared with silicon semiconductors.

So far, various measures have been taken to reduce the cost of silicon carbide semiconductors. For example, Patent Document 1 describes a method for manufacturing a silicon carbide substrate, wherein at least a silicon carbide single crystal substrate and a silicon carbide polycrystalline substrate having a micropipe density of 30 pieces / cm ² or less are prepared, and the silicon carbide is described. A step of bonding (bonding) the single crystal substrate and the silicon carbide polycrystal substrate is performed, and then a step of thinning the single crystal substrate is performed to manufacture a substrate having a single crystal layer formed on the polycrystal substrate. It is stated that.

Further, in Patent Document 1, before the step of bonding the single crystal substrate and the polycrystal substrate, a step of injecting hydrogen ions into the single crystal substrate to form a hydrogen ion injection layer is performed, and the single crystal substrate and the polycrystal substrate are combined. After the step of bonding the single crystal substrate and before the step of thinning the single crystal substrate, the step of performing heat treatment at a temperature of 350 ° C. or lower to thin the single crystal substrate is mechanically performed by the hydrogen ion injection layer. A method for manufacturing a silicon carbide substrate, which is a step of peeling off, is described.

By such a method, more silicon carbide bonded substrates can be obtained from one silicon carbide single crystal ingot.

Japanese Unexamined Patent Publication No. 2009-117533

In the method for manufacturing a silicon carbide wafer described in Patent Document 1, a silicon carbide single crystal substrate on which a thin ion injection layer is formed by injecting hydrogen ions and a silicon carbide polycrystal substrate are bonded together and then heated. It is manufactured by peeling off.

In bonding a bandgap semiconductor substrate such as a silicon carbide single crystal substrate and a handle substrate such as a silicon carbide polycrystalline substrate, the substrates are bonded by a method called room temperature bonding. Generally, first, by irradiating the bonding surface of each substrate with argon (Ar) ions or neutral argon particles in a high vacuum atmosphere, oxygen, hydrogen, and hydroxyl groups on the bonding surface of the substrate are used. The surface is activated by removing interface termination components such as (OH group). After that, it is a method of joining the respective substrates by bringing the activated joining surfaces into contact with each other.

Conventionally, as described above, the surface activation treatment has been carried out by irradiating with argon ions or neutral argon particles. However, in the irradiation of these particles, the particles having mass attack the surface of the substrate, so that a sputtering phenomenon occurs in principle. For this reason, during irradiation, (1) the particles ejected from the substrate or vacuum chamber repelled by spatter are aggregated into particles, and the particles ejected from the substrate or vacuum chamber adhere to the wall surface of the chamber. Two problems can occur: the generation of particles due to subsequent peeling to become particles, and (2) the generation of metal contamination of substances in the vacuum chamber.

Further, the generated particles are sandwiched between the joint surfaces, so that voids may be generated on the joint surface after bonding. Further, it has been confirmed that contamination due to particles protruding from the substrate or the vacuum chamber due to the sputtering phenomenon can cause defects as impurities in the bonded substrate. For this reason, suppressing these problems has become a major issue.

Therefore, an object of the present invention is to provide a substrate bonding apparatus capable of reducing voids and contamination in a bonding substrate manufacturing apparatus for bonding a bandgap semiconductor substrate and a handle substrate.

The substrate bonding device of the present invention is a substrate bonding device for bonding a bandgap semiconductor substrate and a handle substrate to manufacture a bonded substrate, and internally bonds the bandgap semiconductor substrate and the handle substrate. A bonding chamber, a first holder provided inside the bonding chamber and holding one of the bandgap semiconductor substrate and the handle substrate, and one of the bandgap semiconductor substrate and the handle substrate are held. A substrate holder having a second holder, an ultraviolet irradiation device that irradiates at least one bonding surface of the bandgap semiconductor substrate and the handle substrate held by the substrate holder with ultraviolet rays, and a vacuum in the bonding chamber. It is equipped with a vacuum device.

The substrate bonding apparatus of the present invention may further include a heater for heating the bandgap semiconductor substrate held in the substrate holder and the handle substrate.

The substrate bonding apparatus of the present invention may have an adsorption mechanism in which the substrate holder electrostatically adsorbs the bandgap semiconductor substrate and the handle substrate.

In the substrate bonding device of the present invention, the holding surface of the first holder and the holding surface of the second holder face each other in the substrate holder, and the ultraviolet irradiation device can be used as the holding surface of the first holder. And at least one of the substrate holder driving means and the ultraviolet irradiation device driving means arranged between the holding surface of the second holder may be further provided.

In the wafer bonding device of the present invention, the vacuum device may have a turbo molecular pump provided in the vicinity of the first holder and the second holder, respectively.

In the substrate bonding apparatus of the present invention, the ultraviolet irradiation apparatus may have an irradiation source for irradiating ultraviolet rays having a wavelength of 170 nm to 260 nm.

In the substrate joining apparatus of the present invention, the bandgap semiconductor substrate may be a single crystal substrate and the handle substrate may be a polycrystal substrate.

In the substrate bonding apparatus of the present invention, both the bandgap semiconductor substrate and the handle substrate may be silicon carbide substrates.

With the substrate bonding apparatus of the present invention, when a bonding substrate for bonding a bandgap semiconductor substrate and a handle substrate is manufactured, voids and contamination in the bonding substrate can be reduced.

It is a side view which shows typically the bonding chamber of the substrate bonding apparatus which concerns on one Embodiment of this invention. It is a top view schematically showing the bonding chamber of the substrate bonding apparatus shown in FIG. 1. It is a side view schematically showing the state which the substrate is held in the substrate holder in the substrate bonding apparatus shown in FIG. It is a side view schematically showing the state when the substrate held by the substrate holder is irradiated with ultraviolet rays in the substrate joining apparatus shown in FIG. 1. It is a side view schematically showing the state at the time of bonding the substrate held by the substrate holder in the substrate bonding apparatus shown in FIG. 1. In the substrate bonding apparatus shown in FIG. 1, it is a side view schematically showing the state after the substrate is bonded. It is a side view schematically showing the state at the time of transporting a wafer bonding substrate in the wafer bonding apparatus shown in FIG. 1. It is a side view schematically showing the modification of the substrate bonding apparatus shown in FIG. 1. FIG. 9A is a plan view schematically showing a bonded substrate in which voids are generated, and FIG. 9B is a plan view schematically explaining a method of cutting and evaluating a bonded substrate into a chip shape. ..

[Wafer bonding device]
The substrate bonding apparatus according to the embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments.

The substrate bonding apparatus of the present embodiment is used for manufacturing a bonded substrate W, which obtains a bonded substrate W in which a band gap semiconductor substrate S and a handle substrate P are laminated by laminating a band gap semiconductor substrate S and a handle substrate P. Can be applied.

Further, in the production of the bonding substrate W using the substrate bonding apparatus of the present embodiment, a single crystal substrate can be used as the bandgap semiconductor substrate S, and a polycrystalline substrate can be used as the handle substrate P. Further, when the bonded substrate W is manufactured in which the bandgap semiconductor substrate S and the handle substrate P are any one of a silicon carbide (SiC) substrate, a silicon (Si) substrate, and a gallium nitride (GaN) substrate. Can be suitably applied to.

Specifically, for example, when a silicon carbide substrate is obtained as the bonding substrate W, a silicon carbide single crystal substrate can be used as the bandgap semiconductor substrate S, and a silicon carbide polycrystalline substrate can be used as the handle substrate P.

The silicon carbide single crystal substrate used as the band gap semiconductor substrate S is, for example, a 4H-SiC single crystal substrate obtained by processing from a bulk single crystal of silicon carbide prepared by a sublimation method, or a single by a chemical vapor deposition method. A 4H-SiC single crystal substrate obtained by epitaxially growing on a crystal wafer can be used. The silicon carbide single crystal substrate used as the bandgap semiconductor substrate S may contain a dopant such as nitrogen or aluminum.

Further, as the silicon carbide polycrystalline substrate used as the handle substrate P, for example, a 3C-SiC polycrystalline substrate obtained by forming a silicon carbide polycrystalline by a chemical vapor deposition method can be used.

The shape of the bandgap semiconductor substrate S and the handle substrate P may be, for example, a circular parallel flat plate. The thickness of the bandgap semiconductor substrate S and the handle substrate P is not particularly limited, and can be, for example, about 200 μm to 500 μm, respectively.

The substrate bonding device 100 of the present embodiment includes a bonding chamber 10, a substrate holder 20, a heater 30, a transfer robot 40, an ultraviolet irradiation device 50, an adsorption mechanism 60, a vacuum device 70, and a pressurizing means (non-existent). (Illustrated) and. As shown in FIG. 1, the substrate holder 20, the heater 30, the transfer robot 40, the ultraviolet irradiation device 50, the suction mechanism 60, the vacuum device 70, and the pressurizing means are provided in the joining chamber 10. Further, each device in the bonding chamber 10 of the substrate bonding device 100 is formed of stainless steel. In the present embodiment, the direction of arrow A in FIG. 1 is the vertical direction, and the bandgap semiconductor substrate S and the handle substrate P are held vertically facing each other in the substrate bonding apparatus 100, but the direction of arrow A is vertical. Not limited. For example, the arrow A direction may be the horizontal direction (horizontal direction).

1 and 3 to 7 are side views schematically showing a wafer bonding chamber of the wafer bonding apparatus 100, and FIG. 2 is a plan view schematically showing a wafer bonding chamber of the wafer bonding apparatus 100 seen from above. Is. Further, in FIGS. 3 to 6, the first transport table 41, the second transport table 43, a part of the first arm 42, a part of the second arm 44, and the vacuum device 70 are not shown.

The joining chamber 10 is a place for joining the bandgap semiconductor substrate S and the handle substrate P inside.

The substrate holder 20 is provided inside the junction chamber 10 and holds the bandgap semiconductor substrate S and the handle substrate P. The substrate holder 20 includes a first holder 21 that holds either the bandgap semiconductor substrate S or the handle substrate P, and a second holder 22 that holds either the bandgap semiconductor substrate S or the handle substrate P. Have. Which of the bandgap semiconductor substrate S and the handle substrate P is held in the first holder 21 is not particularly limited, but it is more required to suppress the adhesion of dust and the like to the bandgap semiconductor substrate S. , In the following description, it is assumed that the bandgap semiconductor substrate S is held by the first holder 21.

The first holder 21 has a first holding portion 211 that holds the bandgap semiconductor substrate S, and a first arm 212 that is a moving means for moving the first holding portion 211 along the arrow A in FIG. The second holder 22 has a second holding portion 221.

Further, inside the first holding portion 211 and the second holding portion 221 there is a suction mechanism 60 for holding the bandgap semiconductor substrate S and the handle substrate P, and the held bandgap semiconductor substrate S and the handle substrate. A heater 30 for heating the P is provided.

Further, the first holding portion 211 and the second holding portion 221 are provided so that the holding surface 211a of the first holding portion 211 and the holding surface 221a of the second holding portion 221 face each other. As a result, the substrate holder 20 can hold the joint surfaces S1 and P1 of the bandgap semiconductor substrate S and the handle substrate P so as to face each other.

The heater 30 heats the bandgap semiconductor substrate S and the handle substrate P held by the substrate holder 20. The heater 30 has a first heater 31 provided in the first holding portion 211 of the substrate holder 20, and a second heater 32 provided in the second holding portion 221. By providing the heater 30, the bandgap semiconductor substrate S and the handle substrate P can be heated in the step of joining the bandgap semiconductor substrate S and the handle substrate P to increase the bonding strength.

The transfer robot 40 conveys the bandgap semiconductor substrate S, the handle substrate P, and the bonding substrate W in the bonding chamber 10.

The transfer robot 40 holds and conveys the bandgap semiconductor substrate S, the first transfer table 41, the first arm 42 for moving the first transfer table 41, and the second transfer table for holding and transporting the handle substrate P. It has a 43, a second arm 44 for moving the second transport table 43, and an arm shaft portion 45 as an axis on which the first arm 42 and the second arm 44 rotate.

The first transfer table 41 and the second transfer table 43 are provided with a suction mechanism 60, and the suction surface 41a on the upper surface of the first transfer table 41 and the suction surface 43a on the lower surface of the second transfer table 43. The bandgap semiconductor substrate S, the handle substrate P, and the bonding substrate W can be adsorbed and conveyed.

Further, as shown in FIG. 2, the first arm 42 and the second arm 44 can rotate and move around the arm shaft portion 45. That is, the first arm 42 moves along the arrow B and can convey the bandgap semiconductor substrate S and the bonding substrate W that are attracted to and held by the first transfer table 41. Further, the second arm 44 moves along the arrow C and can convey the handle substrate P that is attracted to and held by the second transfer table 43.

The ultraviolet irradiation device 50 irradiates the joint surfaces S1 and P1 of the bandgap semiconductor substrate S and the handle substrate P held by the substrate holder 20 with ultraviolet rays. The ultraviolet irradiation device 50 may irradiate at least one of the bonding surfaces S1 and P1 of the bandgap semiconductor substrate S and the handle substrate P held in the substrate holder 20 with ultraviolet rays, but the bonding surface of the substrate may be used. In order to more reliably activate the ultraviolet rays, as in the present embodiment, ultraviolet rays are applied to both the bonding surfaces S1 and P1 of the bandgap semiconductor substrate S and the handle substrate P held by the substrate holder 20. It is preferably configured.

The ultraviolet irradiation device 50 includes a first irradiation device 51 that irradiates an ultraviolet ray upward to irradiate the band gap semiconductor substrate S, a second irradiation device 52 that irradiates an ultraviolet ray downward to irradiate the handle substrate P, and the like. It has an arm 53 that moves the first irradiation device 51 and the second irradiation device 52 in the direction of arrow D in FIG. As shown in FIG. 1, the first irradiation device 51 and the second irradiation device 52 are vertically integrated.

Further, the first irradiation device 51 has a frame body 511 that is open only upward, and an ultraviolet lamp 512 housed in the frame body 511. The second irradiation device 52 has a frame body 521 that is open only downward and an ultraviolet lamp 522 housed in the frame body 521. The frame 511 and 521 are configured so that ultraviolet rays are not irradiated except in the open vertical direction. As a result, the substrate held in the substrate holder 20 can be efficiently irradiated with ultraviolet rays.

For the ultraviolet lamp 512 and the ultraviolet lamp 522, an irradiation source that irradiates ultraviolet rays having a wavelength of 10 nm to 280 nm can be used, and a particularly easily available irradiation source that irradiates ultraviolet rays having a wavelength of 170 nm to 260 nm can be preferably used. In the present embodiment, as shown in FIGS. 1 and 2, the ultraviolet lamp 512 and the ultraviolet lamp 522 are each composed of five cylindrical Xe excimer lamps, and the five lamps are in the width direction. They are installed side by side. The ultraviolet irradiation source can be variously changed according to the desired wavelength of ultraviolet rays, and is not limited to the Xe excimer lamp (172 nm), and for example, a low pressure mercury lamp (254 nm, 185 nm) or the like can be used.

The arm 53 (ultraviolet irradiation device driving means) is configured to be retractable in the direction of arrow D in FIG. 1, whereby the first irradiation device 51 and the second irradiation device 52 are moved in the direction of arrow D in FIG. Therefore, the first irradiation device 51 and the second irradiation device 52 can be inserted between the holding surface 211a of the first holding portion 211 and the holding surface 221a of the second holding portion 221. That is, the ultraviolet irradiation device 50 has a band gap semiconductor substrate S and a handle substrate in which the first irradiation device 51 and the second irradiation device 52 are held by the arm 53 (ultraviolet irradiation device driving means) facing the substrate holder 20. It can be arranged between the joint surfaces S1 and P1 of P. Further, as a result, the ultraviolet irradiation directions of the first irradiation device 51 and the second irradiation device 52 become perpendicular to the joint surfaces S1 and P1.

Since the ultraviolet irradiation device 50 can be inserted between the joint surfaces S1 and P1 of the band gap semiconductor substrate S and the handle substrate P held facing the substrate holder 20, the first is the first with respect to the joint surfaces S1 and P1. The ultraviolet irradiation direction of the irradiation device 51 and the second irradiation device 52 can be made vertical, and the ultraviolet rays can be uniformly irradiated to the entire joint surfaces S1 and P1 as compared with the case where the ultraviolet rays are irradiated from an oblique direction. .. By uniformly irradiating the joint surfaces S1 and P1 with ultraviolet rays, the entire joint surfaces S1 and P1 can be activated as compared with the case of irradiating the joint surfaces S1 and P1 in an oblique direction.

In the present embodiment, the first irradiation device 51 and the second irradiation device 52 are moved by the arm 53 (ultraviolet irradiation device driving means) of the ultraviolet irradiation device 50, but the substrate bonding device drives the substrate holder. The substrate holder may be moved so that the ultraviolet irradiation device is located between the substrates by providing means. Further, the substrate bonding device is provided with both the substrate holder driving means and the ultraviolet irradiation device driving means, and the substrate holder and the ultraviolet irradiation device move closer to each other so that the ultraviolet irradiation device is located between the substrates. May be.

The suction mechanism 60 electrostatically sucks the bandgap semiconductor substrate S and the handle substrate P, whereby the substrate can be held. The suction mechanism 60 is provided on the first holding portion 211 and the second holding portion 221 of the substrate holder 20, and the first transport base 41 and the second transport base 43 of the transfer robot 40.

By providing the adsorption mechanism 60 for electrostatically adsorbing the substrate, the substrate can be held more reliably, and the substrate can be transported or joined.

The suction mechanism 60 may be provided only on the first holding portion 211 and the second transport table 43 that hold the substrate on the lower surface side. As in the present embodiment, the suction mechanism 60 is also provided on the first transport table 41 and the second holding portion 221 so that the substrate can be held more reliably.

The vacuum device 70 evacuates the inside of the joining chamber 10. Further, the vacuum device 70 has turbo molecular pumps 71 and 72 provided in the vicinity of the first holder 21 and the second holder 22 of the substrate holder 20. That is, the turbo molecular pumps 71 and 72 are provided in the vicinity of the bandgap semiconductor substrate S and the handle substrate P held by the substrate holder 20.

Here, for example, when the bandgap semiconductor substrate S and the handle substrate P both manufacture a bonded substrate W which is a silicon carbide substrate, the vacuum is higher than when the silicon substrate or the like is bonded in the bonding chamber 10. Degree may be required. Even in such a case, the vacuum device 70 has the turbo molecular pumps 71 and 72 provided in the vicinity of the first holder 21 and the second holder 22 of the substrate holder 20, so that the substrate can be activated and joined. The surrounding area can be made into a high vacuum more reliably.

The pressurizing means pressurizes the inside of the joining chamber 10 to a predetermined pressure. The pressurizing method is not particularly limited, and for example, a hydraulic method or the like can be used. The bandgap semiconductor substrate S and the handle substrate P can be joined by applying pressure in a state where the bandgap semiconductor substrate S held in the first holder 21 and the handle substrate P held in the second holder 22 are overlapped with each other. can.

By using the substrate joining device of the present embodiment, activation of the joining surfaces S1 and P1 of the band gap semiconductor substrate S and the handle substrate P and joining of the band gap semiconductor substrate S and the handle substrate P can be performed by one device. Can be done. That is, the time from the activation treatment of the bonding surfaces S1 and P1 to the bonding can be shortened, and the bonding can be performed while maintaining the activated state of the bonding surfaces S1 and P1 more reliably.

[Manufacturing method of bonded substrate]
Next, the operation of the wafer bonding apparatus and the method of manufacturing the wafer bonding substrate will be described. The method for manufacturing a bonded substrate described below is an example of a method for manufacturing a bonded substrate using the substrate bonding apparatus 100 of the present embodiment, and various conditions and the like can be changed within a range where there is no problem.

In the method for manufacturing a bonding substrate using the substrate bonding apparatus of the present embodiment, the bonding surface S1 of the bandgap semiconductor substrate S and the bonding surface P1 of the handle substrate P are activated by irradiating ultraviolet rays under vacuum. After the activation treatment step and the activation treatment step, a bonding step of superimposing and bonding the bonding surface S1 of the bandgap semiconductor substrate S and the bonding surface P1 of the handle substrate P is performed to perform the bonding substrate. W can be manufactured.

In the activation treatment step, the wavelength of ultraviolet rays is preferably a wavelength of 10 nm to 280 nm, and the vacuum is preferably a vacuum degree of 1 × 10 ^-4 Pa or less.

That is, in the activation treatment step, it is preferable not to irradiate the particles having a mass such as Ar, which has been conventionally performed, and instead of irradiating the particles having a mass, the bandgap semiconductor substrate S is irradiated with ultraviolet rays. The joint surface S1 of the above and the joint surface P1 of the handle substrate P are activated.

Further, it is preferable to perform mirror polishing and cleaning of the joint surfaces S1 and P1 of the bandgap semiconductor substrate S and the handle substrate P in advance before the activation treatment step.

(Activation treatment process)
Next, the activation treatment step will be described in detail.

The activation treatment step is performed on at least one of the joint surface S1 of the bandgap semiconductor substrate S and the joint surface P1 of the handle substrate P under vacuum from 10 nm to 280 nm, that is, from VUV (10 nm to 200 nm) to UV-C ( This is a step of irradiating and activating ultraviolet rays in the wavelength range of 200 to 280 nm).

Here, activation of the bonding surfaces S1 and P1 means that the interface termination components such as oxygen, hydrogen, and hydroxyl groups (OH groups) on the bonding surfaces S1 and P1 of the bandgap semiconductor substrate S and the handle substrate P, and the oxide film are used. Refers to removing and forming a dangling bond.

Further, the wavelength of the ultraviolet rays in the activation treatment step can be 170 nm to 260 nm, which is easily available for a lamp as an irradiation source, in the range of 10 nm to 280 nm. When the wavelength of ultraviolet rays is larger than 260 nm, the amount of energy is small, and it may not be possible to apply sufficient energy to the joint surfaces S1 and P1 to promote surface activation.

In the activation treatment step, the activation treatment time for irradiating ultraviolet rays may be any time as long as sufficient energy can be applied to the joint surfaces S1 and P1. Since the amount of energy is the product of the intensity of ultraviolet rays and the irradiation time, the time required for irradiation can be calculated from the intensity of the ultraviolet rays to be irradiated. Specifically, when the intensity of the irradiated ultraviolet rays is, for example, 5 mW / cm ² , it can be about 2 minutes or more.

Further, in the activation treatment step, the degree of vacuum is set to a vacuum of 1 × 10 ^-4 Pa (N / m ² ) or less, more preferably an ultra-high vacuum of 1 × 10 ^-6 Pa or less (JIS Z 8126-1). ). If the degree of vacuum in the activation treatment step is low, the amount of activity on the active surfaces (bonding surfaces S1, P1) after irradiation with ultraviolet rays may be low, and sufficient bonding strength cannot be obtained in the bonding process. There is.

The activation treatment step using the substrate bonding apparatus 100 of the present embodiment is performed by the following procedure.

Prior to the activation treatment step, the inside of the joining chamber 10 is evacuated to a predetermined degree of vacuum (for example, 5 × 10 ^-6 Pa) by a vacuum device 70, and the vacuum state is maintained.

First, the substrate holder 20 holds the bandgap semiconductor substrate S and the handle substrate P. First, the bandgap semiconductor substrate S is placed on the suction surface 41a on the upper surface of the first transport table 41 and held by electrostatic suction, and the handle substrate P is electrostatically sucked on the suction surface 43a on the lower surface of the second transfer table 43. Hold by. At this time, the first transport table 41 and the second transfer table 43 are at the positions shown in FIG. 2 (positions in the initial state).

After that, the first arm 42 is moved toward the substrate holder 20 along the arrow B direction in FIG. 2, and the second arm 44 is moved toward the substrate holder 20 along the arrow C direction in FIG. As a result, the bandgap semiconductor substrate S moves directly below the first holding portion 211 of the substrate holder 20, and the handle substrate P moves directly above the second holding portion 221 of the substrate holder 20.

Further, the electrostatic suction of the suction mechanism 60 of the first transfer table 41 and the second transfer table 43 is switched to the electrostatic suction of the suction mechanism 60 of the first holding portion 211 and the second holding portion 221 of the substrate holder 20. The bandgap semiconductor substrate S is electrostatically attracted to the first holding portion 211, and the handle substrate P is electrostatically attracted to the second holding portion 221 to be held. At this time, the joint surfaces S1 and P1 of the bandgap semiconductor substrate S and the handle substrate P face each other (FIG. 3). After that, the first transport table 41 and the second transfer table 43 are moved in the opposite directions to the initial positions so as to be retracted to the initial position.

Next, as shown in FIG. 4, the arm 53 of the ultraviolet irradiation device 50 is extended to move the first irradiation device 51 and the second irradiation device 52 along the direction of arrow D1 and hold them facing the substrate holder 20. It is inserted between the joint surfaces S1 and P1 of the bandgap semiconductor substrate S and the handle substrate P. At this time, the bandgap semiconductor substrate S, the first irradiation device 51, the second irradiation device 52, and the handle substrate P are located side by side in a straight line in the vertical direction.

Further, the ultraviolet lamps 512 and 522 apply ultraviolet rays to the joint surface S1 of the bandgap semiconductor substrate S and the joint surface P1 of the handle substrate P with a predetermined intensity (for example, 172 nm ultraviolet rays at 10 mW / cm ² ) for a predetermined time (for example, for example. Irradiate for 2 minutes (Fig. 4). As a result, the joint surfaces S1 and P1 are activated, and the activation treatment step is completed.

In the above description, an example of irradiating both the joint surface S1 of the bandgap semiconductor substrate S and the joint surface P1 of the handle substrate P with ultraviolet rays is shown, but the irradiation of ultraviolet rays is the bonding of the bandgap semiconductor substrate S. It may be performed on at least one of the surface S1 and the joint surface P1 of the handle substrate P.

(Joining process)
Next, the joining process will be described.

The joining step is a step of joining the joining surface S1 of the bandgap semiconductor substrate S and the joining surface P1 of the handle substrate P to obtain the joining substrate W after the activation treatment step. In the joining step described below, the joining surface S1 of the bandgap semiconductor substrate S and the joining surface P1 of the handle substrate P are surfaces irradiated with ultraviolet rays in the activation treatment step.

It is preferable to join the bandgap semiconductor substrate S and the handle substrate P while the activated states of the joining surfaces S1 and P1 are maintained, and the time between the activation treatment step and the joining step is set. It is preferably within a few seconds to 1 minute.

The optimum temperature of the bandgap semiconductor substrate S and the handle substrate in the joining process varies depending on the type and combination of the bandgap semiconductor substrate S and the handle substrate P, but is, for example, about 200 ° C to 400 ° C. be able to.

If the temperatures of the bandgap semiconductor substrate S and the handle substrate in the joining process are too low, such as lower than 200 ° C., sufficient bonding strength between the bandgap semiconductor substrate S and the handle substrate P cannot be obtained, and voids cannot be obtained. May not be sufficient to reduce the occurrence of. If the temperatures of the bandgap semiconductor substrate S and the handle substrate in the joining process are too high, such as higher than 400 ° C., strain may occur between the bandgap semiconductor substrate S and the handle substrate P, and after the joining process, One or both substrates may crack during cooling.

Further, in the joining step, the pressure applied to the bandgap semiconductor substrate S and the handle substrate P by using the pressurizing means can be 50 kgf to 500 kgf (0.49 kN to 4.90 kN).

Further, the degree of vacuum in the joining chamber 10 in the joining step can be set to the same conditions as in the activation treatment step.

Further, the processing time in the joining step is not particularly limited as long as the bandgap semiconductor substrate S and the handle substrate P are sufficiently joined, and can be, for example, 10 seconds to 5 minutes.

The bonding step using the substrate bonding device 100 of the present embodiment is performed by the following procedure.

As shown in FIG. 5, the arm 53 of the ultraviolet irradiation device 50 is contracted, the first irradiation device 51 and the second irradiation device 52 are moved along the arrow D1 direction, and the ultraviolet irradiation device 50 is retracted. Then, the first arm 212 of the substrate holder 20 is extended, and the bandgap semiconductor substrate is held by the first holding portion 211 up to a position where the joint surfaces S1 and P1 come into contact with each other and overlap with each other along the direction of arrow A1 in FIG. Move S.

Here, in the activation processing step, the bandgap semiconductor substrate S, the first irradiation device 51, the second irradiation device 52, and the handle substrate P were arranged in a straight line in the vertical direction, so that the bandgap semiconductor substrate S and the bandgap semiconductor substrate S were arranged. The movement of stacking the handle substrates P can be performed in the minimum required time and distance, the time between the activation treatment step and the joining step is shortened, and dust and the like adhere to the activated joining surfaces S1 and P1. It can be suppressed.

After moving the bandgap semiconductor substrate S to a position where the joint surfaces S1 and P1 are in contact with each other and overlap each other, the bandgap semiconductor substrate S and the handle substrate P are further heated by the first heater 31 and the second heater 32. Along with the heating of the substrate, the stacked bandgap semiconductor substrate S and the handle substrate P are pressurized inside the bonding chamber 10 to a predetermined pressure (for example, 100 kgf (0.98 kN)) by a pressurizing means, and the pressure is applied for a predetermined time (for example, 3). By holding for a minute), the bandgap semiconductor substrate S and the handle substrate P are joined. As a result, the bonding substrate W is formed.

Next, the formed bonding substrate W is collected. Only the electrostatic adsorption of the adsorption mechanism 60 of the second holding portion 221 is cut off, the bonding substrate W is held by the first holding portion 211 by electrostatic adsorption, and then the first arm 212 is shrunk as shown in FIG. The first holding portion 211 is returned to the initial position along the direction of arrow A1 in FIG. Next, as shown in FIG. 7, the first arm 42 is moved toward the board holder 20 along the arrow B direction in FIG. 2, and the first transfer table 41 is moved to just below the first holding portion 211 of the board holder 20. Move it. Then, the suction mechanism 60 of the first holding portion 211 is switched to the suction mechanism 60 of the first transport table 41, and the bonding substrate W is held by the first transfer table 41. Finally, the first arm 42 is moved in the opposite direction to the previous one to return the first transfer table 41 to the initial position, and the bonding substrate W is collected. With the above, the production of the bonding substrate W is completed.

(Comparison with conventional bonding substrate manufacturing method and manufacturing equipment)
In the conventional bonding substrate manufacturing method and manufacturing equipment, in order to activate the bonding surface, argon (Ar) ions and neutral argon particles are irradiated on the bonding surface of each substrate to bond the substrates. The surface was activated by removing interface termination components such as oxygen, hydrogen, and hydroxyl groups (OH groups) on the surface.

However, irradiation of argon ions and argon particles is an attack by particles having mass, and a sputtering phenomenon occurs in principle. Therefore, (1) generation of particles derived from particles repelled by sputtering, and (2) vacuum chamber. The generation of metal contamination of the material inside was a problem. Further, due to the sputtering phenomenon on the bonded surface by the particles having mass, the bonded surface becomes a non-uniform uneven surface, which causes voids (voids, for example, bonding of FIG. 9A) in the bonded surface after bonding. It causes void V) in the substrate 700. In addition, contamination due to particles protruding from the substrate or vacuum chamber due to the sputtering phenomenon has been a cause of defects in the bonded substrate.

The voids generated in the bonded substrate can be observed using an optical microscope, a laser microscope, or the like.

By activating the joint surface by irradiating the joint surface between the bandgap semiconductor substrate and the handle substrate with ultraviolet rays, the present inventors activate the joint surface without causing particles or metal contamination due to sputter particles such as argon particles. It has been found that a modified joint surface can be obtained.

Since the substrate bonding apparatus of the present embodiment can activate the bonding surface S1 of the bandgap semiconductor substrate S and the bonding surface P1 of the handle substrate P without using particles having a mass such as argon, the void can be activated. And it is possible to obtain a bonded substrate W with reduced contamination.

The present invention is not limited to the above-described embodiment, but includes other configurations and the like that can achieve the object of the present invention, and the present invention also includes modifications and the like of the above-mentioned embodiment.

For example, in the wafer bonding device 100A shown in FIG. 8, the moving directions of the first transfer table 41 and the second transfer table 43 are different from those of the wafer bonding device 100 of the above-described embodiment. That is, the transfer robot 40A has a first transfer table 41, a first arm 42A, a second transfer table 43, a second arm 44A, and an arm support portion 45A. In the modification shown in FIG. 8, the first arm 42A expands and contracts in the direction of arrow E, and the second arm expands and contracts in the direction of arrow F to move the first transfer table 41 and the second transfer table 43. can. As described above, the method of moving the first transfer table and the second transfer table is not limited to the above-described embodiment and the present modification, and the substrate can be moved between the transfer robot and the substrate holder. Any configuration may be used as long as it is a thing.

Further, in the above-described embodiment, the device for processing the bandgap semiconductor substrate S and the handle substrate P one by one has been described, but the substrate holder and the carrier for handling the plurality of bandgap semiconductor substrates S and the handle substrate P have been described. By using a robot, a plurality of substrates may be processed in one manufacturing batch.

In addition, the best configuration, method, etc. for carrying out the present invention are disclosed in the above description, but the present invention is not limited thereto. That is, although the present invention has been described mainly with respect to a specific embodiment, the shape, material, quantity, and the like, without departing from the scope of the technical idea and purpose of the present invention, are as compared to the above-described embodiments. In other detailed configurations, those skilled in the art can make various modifications. Therefore, the description limiting the shape, material, etc. disclosed above is merely an example for facilitating the understanding of the present invention, and does not limit the present invention. Therefore, those shapes, materials, etc. The description by the name of the member excluding a part or all of the limitation such as is included in the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to these examples.

In this embodiment, silicon carbide is bonded by using a silicon carbide single crystal substrate as a bandgap semiconductor substrate and a silicon carbide polycrystal substrate as a handle substrate, and the silicon carbide single crystal substrate and the silicon carbide polycrystal substrate are bonded. Manufactured a bonded substrate. Further, as the manufacturing apparatus, the substrate bonding apparatus 100 of the above-described embodiment was used. The substrate bonding device 100 includes an Xe excimer lamp as an ultraviolet lamp 512 and an ultraviolet lamp 522.

[Example 1]
(Manufacturing of silicon carbide bonded substrate)
As the silicon carbide single crystal substrate, a 4H-SiC single crystal substrate having a diameter of 4 inches, which was produced by the sublimation method, was used. Further, as the silicon carbide polycrystalline substrate, a 3C-SiC polycrystalline substrate having a diameter of 4 inches obtained by forming a silicon carbide polycrystalline by a chemical vapor deposition method was used.

First, before the activation treatment step, the joint surface between the silicon carbide single crystal substrate and the silicon carbide polycrystalline substrate was subjected to mirror polishing and cleaning. Next, as an activation treatment step, the joint surface between the silicon carbide single crystal substrate and the silicon carbide polycrystalline substrate, which had been mirror-polished and washed, was irradiated with ultraviolet rays without irradiating Ar ions and Ar particles.

That is, the silicon carbide single crystal substrate and the silicon carbide polycrystalline substrate were held in the substrate holder 20 to create an ultra-high vacuum atmosphere having a vacuum degree of 5 × 10 ^-6 Pa or less in the bonding chamber 10. Further, the joint surface between the silicon carbide single crystal substrate and the silicon carbide polycrystalline substrate was irradiated with ultraviolet rays having a wavelength of 172 nm for 2 minutes at an intensity of 10 mW / cm ² by an Xe excimer lamp (ultraviolet lamp 512, ultraviolet lamp 522).

Next, a joining step was performed. The silicon carbide single crystal substrate and the silicon carbide polycrystalline substrate are stacked so that the activated bonding surfaces are in contact with each other, and the inside of the bonding chamber 10 is set to 300 ° C. and carbonized while maintaining the same vacuum conditions as in the activation treatment step. A pressure of 100 kgf (0.98 kN) was applied to a stack of a silicon single crystal substrate and a silicon carbide polycrystalline substrate, and the mixture was held for 3 minutes. From the above, a bonded substrate of a silicon carbide single crystal substrate and a silicon carbide polycrystalline substrate was obtained. Further, after the temperature inside the bonding chamber 10 was lowered to room temperature, the pressure inside the bonding chamber 10 was restored to atmospheric pressure, the bonding substrate was taken out, and the bonding substrate was evaluated.

(Evaluation of silicon carbide bonded substrate)
The obtained bonded substrate was evaluated. The evaluation was to confirm the presence or absence of voids, the presence or absence of contamination, and the confirmation of joint strength.

To confirm the presence or absence of voids, microscopic observation was performed using an optical microscope, and it was confirmed whether or not voids were generated in the obtained bonded substrate. When voids are generated in the bonded substrate, point-shaped voids V can be confirmed as in the bonded substrate 700 shown in FIG.

Further, by subjecting the bonded substrate to fluorescent X-ray analysis, it was confirmed whether or not the bonded substrate contained impurities, and the presence or absence of contamination was evaluated. NANOHUNTERII (manufactured by Rigaku) was used as a fluorescent X-ray analyzer.

As for the bonding strength, the obtained bonded substrate was cut into 5 mm square chips, and the presence or absence of peeling between the silicon carbide single crystal substrate and the silicon carbide polycrystalline substrate was confirmed, and the peeling was 3 out of 270. When it was the following, it was evaluated that the bonding strength was sufficient, and when it was more than 5, it was evaluated that the bonding strength was insufficient.

Even if the bonding strength of the bonding substrate is sufficient, if void V is generated in the bonding substrate as in the bonding substrate 800 shown in FIG. 9B, a chip that does not contain the void V (for example, FIG. The chip 810) of 9 (B) is a good product, but a chip containing a void V (for example, chips 820, 830, 840 of FIG. 9 (B)) may cause a defect when used in a subsequent process. Therefore, it can be evaluated that the higher the number of chips containing the void V, the lower the yield.

As a result of evaluating the bonded substrate, no voids were confirmed, and the measurement of metal impurities was below the acceptance limit, and no contamination was confirmed. Further, when the bonded substrate was cut into 270 5 mm square chips, no peeling was confirmed, and it was judged that the bonding strength was sufficient.

[Example 2]
As Example 2, the bonding substrate was manufactured and the bonding substrate was evaluated in the same manner as in Example 1 except that the Xe excimer lamp of the substrate bonding apparatus 100 was irradiated to the substrate from an oblique direction. As a result of evaluating the obtained bonded substrate, the generation of voids was not confirmed, and the measurement of metal impurities was below the acceptance limit, and no contamination was confirmed. Further, when the bonded substrate was cut into 5 mm square chips, peeling was confirmed on only one of the 270 chips. From the above, it was shown that although the bonding strength is sufficient, the bonding strength can be further increased by irradiating the substrate with ultraviolet rays in the vertical direction.

In Examples 1 and 2 using the substrate bonding apparatus 100 which is an exemplary embodiment of the present invention, ultraviolet rays are applied to the bonding surface between the bandgap semiconductor substrate and the handle substrate without irradiating particles having a mass such as Ar. It is shown that by activating the joint surface by irradiation, a joint substrate with reduced voids and contamination in the joint substrate can be obtained without causing particles or metal contamination due to sputter particles such as argon particles. Was done.

100 Board joining device 10 Joining chamber 20 Board holder 30 Heater 40 Transfer robot 50 Ultraviolet irradiation device 53 Arm (ultraviolet irradiation device driving means)
60 Adsorption mechanism 70 Vacuum device 71, 72 Turbo molecular pump S Bandgap semiconductor substrate S1 Bandgap semiconductor substrate bonding surface P Handle substrate P1 Handle substrate bonding surface W Bonding substrate

Claims (8)

A substrate bonding device for manufacturing a bonded substrate by bonding a bandgap semiconductor substrate and a handle substrate.
Inside, a joining chamber for joining the bandgap semiconductor substrate and the handle substrate, and
A first holder provided inside the junction chamber and holding one of the bandgap semiconductor substrate and the handle substrate, and a second holder holding either the bandgap semiconductor substrate and the handle substrate. With a board holder,
An ultraviolet irradiation device that irradiates at least one joint surface between the bandgap semiconductor substrate and the handle substrate held by the substrate holder.
A substrate bonding device including a vacuum device that evacuates the bonding chamber. The substrate bonding apparatus according to claim 1, further comprising a heater for heating the bandgap semiconductor substrate held in the substrate holder and the handle substrate. The substrate bonding apparatus according to claim 1 or 2, wherein the substrate holder has an adsorption mechanism for electrostatically adsorbing the bandgap semiconductor substrate and the handle substrate. In the substrate holder, the holding surface of the first holder and the holding surface of the second holder face each other.
Claim 1 to further include at least one of a substrate holder driving means and an ultraviolet irradiation device driving means, in which the ultraviolet irradiation device is arranged between the holding surface of the first holder and the holding surface of the second holder. 3. The substrate bonding apparatus according to any one of 3. The substrate bonding apparatus according to any one of claims 1 to 4, wherein the vacuum apparatus has a turbo molecular pump provided in the vicinity of the first holder and the second holder, respectively. The substrate bonding apparatus according to any one of claims 1 to 5, wherein the ultraviolet irradiation device has an irradiation source that irradiates ultraviolet rays having a wavelength of 170 nm to 260 nm. The substrate bonding apparatus according to any one of claims 1 to 6, wherein the bandgap semiconductor substrate is a single crystal substrate and the handle substrate is a polycrystalline substrate. The substrate bonding apparatus according to any one of claims 1 to 7, wherein both the bandgap semiconductor substrate and the handle substrate are silicon carbide substrates.

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