This application claims the benefit of Japanese Patent Application No. 2013-012326, filed on Jan. 25, 2013, in the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference.
The present disclosure relates to a joining device which joins substrates together and a joining system provided with the joining device.
In recent years, high integration of semiconductor devices has been prompted. However, when a plurality of highly integrated semiconductor devices is arranged on a horizontal plane and is connected by wiring into a product, the length of the wiring may increase the resistance and make the delay of the wiring large.
Accordingly, the use of a three dimensional integration technology has been proposed which integrates semiconductor devices in three dimensions. In the three dimensional integration technology, for example, a joining system is used to join two semiconductor wafers (hereinafter, referred to as “wafers”) together. For example, the joining system includes a surface hydrophilization device which hydrophilizes the joining surfaces of wafers and a joining device which joins the wafers whose surfaces are hydrophilized by the surface hydrophilization device. In this joining system, the surface hydrophilization device hydrophilizes the surfaces of the wafers by supplying pure water to the surfaces of the wafers. Thereafter, two wafers are disposed in the joining device in a vertically opposing relationship (hereinafter, a wafer positioned at an upper side is referred to as an “upper wafer” and a wafer positioned at a lower side is referred to as a “lower wafer”). The upper wafer drawn and held by an upper chuck and the lower wafer drawn and held by a lower chuck are joined together by the Van der Waals force and by a hydrogen bond (an intermolecular force).
The lower chuck has, e.g., a flat plate shape, and draws and holds the lower wafer on the entire upper surface thereof. However, it is often the case that, due to the existence of irregularities on the upper surface of the lower chuck or the existence of particles or the like on the upper surface of the lower chuck, the upper surface of the lower chuck becomes uneven (or has a large flatness). In this case, the flatness of the lower chuck is transferred to the lower wafer. If the lower wafer and the upper wafer are joined together, a vertical distortion is generated in the joined superposed wafer.
In order to make the upper surface of the lower chuck flat, the upper surface of the lower chuck is sometimes subjected to, e.g., lapping, mirror treatment or the like. However, if the flatness of the upper surface of the lower chuck grows exceedingly smaller, thereby making the surface texture too fine, the lower wafer is hardly separated from the lower chuck when the vacuum suction of the lower wafer is released.
Some embodiments of the present disclosure suppress a vertical distortion of a joined superposed substrate by appropriately holding substrates when the substrates are joined together.
According to an embodiment of the present disclosure, provided is a joining device for joining substrates together, including a first holding member configured to vacuum-suck a first substrate to draw and hold the first substrate on a lower surface thereof, and a second holding member disposed below the first holding member and configured to vacuum-suck a second substrate to draw and hold the second substrate on an upper surface thereof, wherein the second holding member includes a body portion formed into a size larger than the second substrate when seen in a plan view and configured to vacuum-suck the second substrate, a plurality of pins provided on the body portion and configured to make contact with a rear surface of the second substrate, and an outer wall portion annularly provided on the body portion at an outer side of the plurality of pins and configured to support an outer periphery portion of the rear surface of the second substrate.
According to another embodiment of the present disclosure, provided is a joining system provided with the above described joining device, the joining system including a processing station including the joining device, and a carry-in/carry-out station configured to retain the first substrate, the second substrate or a superposed substrate obtained by joining the first substrate and the second substrate together, and configured to carry the first substrate, the second substrate or the superposed substrate into and out of the processing station, wherein the processing station includes a surface modification device configured to modify a front surface of the first substrate to be joined or a front surface of the second substrate to be joined, a surface hydrophilization device configured to hydrophilize the front surface of the first substrate or the second substrate modified by the surface modification device, and a transfer zone in which the first substrate, the second substrate or the superposed substrate is transferred with respect to the surface modification device, the surface hydrophilization device and the joining device, wherein the joining device is configured to join the first substrate and the second substrate whose front surfaces are hydrophilized by the surface hydrophilization device.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.
Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, systems, and components have not been described in detail so as not to unnecessarily obscure aspects of the various embodiments.
Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings.
In the joining system 1, for example, two wafers WU and WL as substrates are joined together as shown in
As shown in
A cassette mounting stand 10 is disposed in the carry-in/carry-out station 2. A plurality of (e.g., four) cassette mounting boards 11 are mounted on the cassette mounting stand 10. The cassette mounting boards 11 are arranged in a line along an X-axis direction (vertical direction in
In the carry-in/carry-out station 2, a wafer transfer section 20 is disposed adjacent to the cassette mounting stand 10. The wafer transfer section 20 is provided with a wafer transfer unit 22 movable along a transfer path 21 extending in the X-axis direction. The wafer transfer unit 22, which is movable in a vertical direction and is also rotatable about a vertical axis (or in a θ direction), transfers the wafer WU, the wafer WL and the superposed wafer WT between the cassettes CU, CL and CT mounted on the respective cassette mounting boards 11, and transition units 50 and 51 of a third processing block G3 of the processing station 3, which will be described later.
The processing station 3 is provided with a plurality of (e.g., three) processing blocks G1, G2 and G3, which include various processing units. The first processing block G1 is disposed at, e.g., the front side of the processing station 3 in the X-axis direction (at the lower side in
The first processing block G1 is provided with, e.g., a surface modification device 30 configured to modify the front surfaces WU1 and WL1 of the wafers WU and WL. In the present embodiment, the surface modification device 30 cuts the bonds of SiO2 of the front surfaces WU1 and WL1 of the wafers WU and WL to obtain SiO having a single bond, thereby modifying the front surfaces WU1 and WL1 so that they can be easily hydrophilized later.
The second processing block G2 is provided with a surface hydrophilization device 40 configured to hydrophilize and clean the front surfaces WU1 and WL1 of the wafers WU and WL with, e.g., pure water, and a joining device 41 configured to join the wafers WU and WL together, which are arranged in the named order from the carry-in/carry-out station 2 in the Y-axis direction.
The third processing block G3 is provided with the transition units 50 and 51 configured to move the wafers WU and WL and the superposed wafer WT, which are stacked in two stages in order from the bottom to the top, as shown in
As shown in
The wafer transfer unit 61 is equipped with a transfer arm (not shown) which is movable in the vertical and horizontal directions (the X and Y-axis directions) and is rotatable about a vertical axis. The wafer transfer unit 61 moves inside the wafer transfer zone 60 so that the wafers WU and WL and the superposed wafer WT can be transferred to specified units installed in the first to third processing blocks G1, G2 and G3.
Next, a configuration of the abovementioned surface modification device 30 will be described. As shown in
An inlet/outlet 101 through which the wafers WU and WL are transferred is formed on the side surface of the side of the processing vessel 100 facing the wafer transfer zone 60. A gate valve 102 is provided at the inlet/outlet 101.
A suction port 103 is formed on the bottom surface of the processing vessel 100. A suction pipe 105 communicating with a suction unit 104 for depressurizing the internal atmosphere of the processing vessel 100 to a predetermined vacuum degree is connected to the suction port 103.
A mounting table 110 for mounting the wafers WU and WL thereon is provided on the bottom surface of the processing vessel 100. The mounting table 110 can mount the wafers WU and WL thereon by, e.g., electrostatic drawing or vacuum suction. An ion ammeter 111 configured to measure an ion current generated by ions (oxygen ions) of a process gas irradiated toward the wafers WU and WL mounted on the mounting table 110 in the below-mentioned manner is installed in the mounting table 110.
A temperature adjusting mechanism 112 configured to allow, e.g., a cooling medium, to flow therethrough is installed within the mounting table 110. The temperature adjusting mechanism 112 is connected to a liquid temperature adjusting unit 113 which serves to adjust the temperature of the cooling medium. The temperature of the cooling medium is adjusted by the liquid temperature adjusting unit 113, which makes it possible to control the temperature of the mounting table 110. As a result, the wafers WU and WL mounted on the mounting table 110 can be kept at a predetermined temperature.
Lift pins (not shown) for supporting the wafers WU and WL from below and moving the wafers WU and WL up and down are provided below the mounting table 110. The lift pins are inserted into through-holes (not shown) formed in the mounting table 110 and can protrude from the upper surface of the mounting table 110.
A radial line slot antenna 120 configured to supply plasma-generating microwaves is provided in the upper surface opening of the processing vessel 100. The radial line slot antenna 120 includes an antenna body 121 which has a lower surface opening. A flow path (not shown) configured to allow, e.g., a cooling medium, to flow therethrough is provided within the antenna body 121.
A slot plate 122 having a plurality of slots and serving as an antenna is provided in the lower surface opening of the antenna body 121. An electrically conductive material, e.g., copper, aluminum or nickel, is used as the material of the slot plate 122. A lagging plate 123 is provided above the slot plate 122 within the antenna body 121. A low-loss dielectric material, e.g., quartz, alumina or aluminum nitride, is used as the material of the lagging plate 123.
A microwave-transmitting plate 124 is provided below the antenna body 121 and the slot plate 122. The microwave-transmitting plate 124 is arranged through a seal material (not shown), e.g., an O-ring, to close the interior of the processing vessel 100. A dielectric material, e.g., quartz or Al2O3, is used as the material of the microwave-transmitting plate 124.
A coaxial waveguide pipe 126 communicating with a microwave generating unit 125 is connected to the upper portion of the antenna body 121. The microwave generating unit 125 is provided outside the processing vessel 100 and can supply microwaves of predetermined frequency, e.g., 2.45 GHz, to the radial line slot antenna 120.
With this configuration, the microwaves generated from the microwave generating unit 125 are propagated into the radial line slot antenna 120 and are compressed by the lagging plate 123 to have a short wavelength, thereby generating circularly polarized waves in the slot plate 122, which, in turn, are transmitted through the microwave-transmitting plate 124 and irradiated toward the interior of the processing vessel 100.
A gas supply pipe 130 configured to supply an oxygen gas as a process gas into the processing vessel 100 is connected to the side surface of the processing vessel 100. The gas supply pipe 130 is arranged above an ion passing structural body 140 to be described later and is configured to supply an oxygen gas to a plasma generation region R1 defined within the processing vessel 100. The gas supply pipe 130 communicates with a gas supply source 131 which retains an oxygen gas therein. A supply kit 132 including a valve, a flow rate adjusting unit or the like, which control the flow of an oxygen gas, is provided in the gas supply pipe 130.
An ion passing structural body 140 is provided between the mounting table 110 within the processing vessel 100 and the radial line slot antenna 120. That is, the ion passing structural body 140 is provided to divide the interior of the processing vessel 100 into a plasma generation region R1 in which the oxygen gas supplied from the gas supply pipe 130 is turned to plasma by the microwaves irradiated from the radial line slot antenna 120 and a processing region R2 in which the front surfaces WU1 and WL1 of the wafers WU and WL mounted on the mounting table 110 are modified by oxygen ions generated in the plasma generation region R1.
The ion passing structural body 140 includes a pair of electrodes 141 and 142. In the following description, the electrode disposed at the upper side will be sometimes referred to as an “upper electrode 141” and the electrode disposed at the lower side will be sometimes referred to as a “lower electrode 142”. An insulating material 143 configured to electrically insulate the electrodes 141 and 142 from each other is provided between the electrodes 141 and 142.
As shown in
In some embodiments the dimension of each of the openings 144 is set, e.g., smaller than the wavelength of the microwaves irradiated from the radial line slot antenna 120. This ensures that the microwaves supplied from the radial line slot antenna 120 are reflected by the ion passing structural body 140 and are restrained from entering the processing region R2. As a consequence, the wafers WU and WL mounted on the mounting table 110 are not directly exposed to the microwaves. This makes it possible to prevent the wafers WU and WL from being damaged by the microwaves.
A power supply 145 configured to apply a predetermined voltage between the electrodes 141 and 142 is connected to the ion passing structural body 140. The predetermined voltage applied by the power supply 145 is controlled by a control unit 300 to be described later. The maximum voltage applied by the power supply 145 is, e.g., 1 KeV. An ammeter 146 configured to measure the electric current flowing between the electrodes 141 and 142 is connected to the ion passing structural body 140.
Next, a configuration of the aforementioned surface hydrophilization device 40 will be described. As shown in
As shown in
A chuck drive unit 161 equipped with, e.g., a motor, is installed below the spin chuck 160. The spin chuck 160 can be rotated at a predetermined speed by the chuck drive unit 161. The chuck drive unit 161 is provided with an up-down drive source (not shown) such as a cylinder or the like and can move the spin chuck 160 up and down.
A cup 162 is provided around the spin chuck 160 to receive and collect liquid dropped or scattered from the wafer WU (or WL). A discharge pipe 163 configured to drain the collected liquid and an exhaust pipe 164 configured to vacuum-suck and discharge an atmosphere within the cup 162 are connected to the bottom surface of the cup 162.
As shown in
As shown in
As shown in
The scrub arm 172 supports a scrub cleaning tool 180. For example, a plurality of brushes 180a having a string-like shape or a sponge-like shape is formed at a tip end of the scrub cleaning tool 180. The scrub arm 172 is movable along the rail 170 by operating a cleaning tool drive unit 181 shown in
In the above configuration, the pure water nozzle 173 and the scrub cleaning tool 180 are supported by different arms. However, the pure water nozzle 173 and the scrub cleaning tool 180 may be supported by a single arm. In one embodiment, the pure water may be supplied from the scrub cleaning tool 180 without the pure water nozzle 173. In some embodiments, a discharge pipe configured to discharge the liquid and an exhaust pipe configured to exhaust the internal atmosphere of the processing vessel 150 may be connected to the bottom surface of the processing vessel 150, without the cup 162. In some embodiments, the surface hydrophilization device 40 configured as above may include an antistatic ionizer (not shown).
Next, a configuration of the abovementioned joining device 41 will be described. As shown in
The interior of the processing vessel 190 is partitioned into a transfer region T1 and a processing region T2 by an internal wall 193. The inlet/outlet 191 mentioned above is formed in a lateral side of the processing vessel 190 facing the wafer transfer zone 60 in the transfer region T1. Further, an inlet/outlet 194, through which the wafer WU (or WL) and the superposed wafer WT are transferred, is formed in the internal wall 193.
A transition 200, on which the wafer WU (or WL) and the superposed wafer WT are temporarily mounted, is formed at the forward side (the top side in
A wafer transfer mechanism 201 is installed in the transfer region T1. As shown in
A position adjusting mechanism 210 configured to adjust a horizontal orientation of the wafer WU (or WL) is disposed at the back side of the transfer region T1 in the X-axis direction. As shown in
An inverting mechanism 220 configured to invert the front and rear surfaces of the upper wafer WU is installed in the transfer region T1. As shown in
As shown in
As shown in
As shown in
The lower chuck 231 is held by a lower chuck holding unit 235. The lower chuck holding unit 235 draws and holds the lower chuck 231 by vacuum-sucking the same. This suppresses the vertical distortion of the lower chuck 231 and reduces the flatness of the upper surface of the lower chuck 231. A lower chuck drive unit 237 is installed below the lower chuck holding unit 235 through a shaft 236. The lower chuck 231 can be vertically and horizontally moved by the lower chuck drive unit 237. Moreover, the lower chuck 231 can be rotated about a vertical axis by the lower chuck drive unit 237. Lift pins (not shown) for supporting the lower wafer WL from below and moving the lower wafer WL up and down are installed below the lower chuck holding unit 235. The lift pins are inserted into the below-mentioned through-holes 277 formed in the lower chuck 231 (the lower chuck holding unit 235) and can protrude from the upper surface of the lower chuck 231.
As shown in
Suction ports 244 for vacuum-sucking the upper wafer WU are formed on the lower surface of the body portion 240 in an inner region of the outer wall portion 242 (hereinafter often referred to as a “suction region 243”). The suction ports 244 are formed, e.g., at two points in the outer periphery portion of the suction region 243. Suction pipes 245 installed inside the body portion 240 are connected to the suction ports 244. A vacuum pump 246 is connected to the suction pipes 245 through a joint.
The suction region 243 surrounded by the upper wafer WU, the body portion 240 and the outer wall portion 242 is vacuum-sucked via the suction ports 244 to be depressurized. At this time, the external atmosphere of the suction region 243 is kept at atmospheric pressure. Therefore, the upper wafer WU is pressed toward the suction region 243 by the atmospheric pressure just as much as the depressurized amount, whereby the upper wafer WU is drawn and held by the upper chuck 230.
In this case, the pins 241 are uniform in height, which makes it possible to reduce the flatness of the lower surface of the upper chuck 230. By making the lower surface of the upper chuck 230 flat (by reducing the flatness of the lower surface of the upper chuck 230) in this manner, it is possible to suppress the vertical distortion of the upper wafer WU held by the upper chuck 230. Since the rear surface WU2 of the upper wafer WU is supported by the pins 241, the upper wafer WU is easily separated from the upper chuck 230 upon releasing the vacuum-suction applied to the upper wafer WU by the upper chuck 230.
A through-hole 247 extending through the body portion 240 in the thickness direction thereof is formed in the central area of the body portion 240. The central area of the body portion 240 corresponds to the central portion of the upper wafer WU drawn and held by the upper chuck 230. A pressing pin 261 of a pressing member 260 (which will be described later) is inserted into the through-hole 247.
The aforementioned upper chuck holding unit 232 configured to support the upper chuck 230 includes a support member 250 on which the pressing member 260 to be described later is installed and a position adjusting mechanism 251 installed on the support member 250 and configured to adjust the position of the upper chuck 230 such that a predetermined gap, e.g., a gap of 1 mm in size, is formed between the upper chuck 230 and the support member 250. The position adjusting mechanism 251 suppresses the tilt of the upper chuck 230 and maintains the parallelism of the upper chuck 230.
The pressing member 260 configured to press the central portion of the upper wafer WU is installed on the support member 250. The pressing member 260 has a cylinder structure and includes a pressing pin 261 and an outer tube 262 which serves as a guide during the up/down movement of the pressing pin 261. The pressing pin 261 can be vertically moved through the through-hole 247 by a drive unit (not shown) equipped with, e.g., a motor. During the below-mentioned joining process of the wafers WU and WL, the pressing member 260 can bring the central portion of the upper wafer WU and the central portion of the lower wafer WL into contact with each other and can press them against each other.
An upper image pickup member 263 configured to pick up an image of the front surface WL1 of the lower wafer WL is disposed in the upper chuck 230. Examples of the upper image pickup member 263 may include a wide-angle CCD (Charge-Coupled Device) camera. In some embodiments, the upper image pickup member 263 may be disposed above the upper chuck 230.
As shown in
A plurality of suction ports 274 for vacuum-sucking the lower wafer WL are formed on the upper surface of the body portion 270 in an inner region 273 of the outer wall portion 272 (hereinafter often referred to as a “suction region 273”). Suction pipes 275 installed inside the body portion 270 are connected to the suction ports 274. For example, two suction pipes 275 are installed. A vacuum pump 276 is connected to the suction pipes 275.
The suction region 273 surrounded by the lower wafer WL, the body portion 270 and the outer wall portion 272 is vacuum-sucked from the suction ports 274 to depressurize the suction region 273. At this time, the external atmosphere of the suction region 273 is kept at atmospheric pressure. Therefore, the lower wafer WL is pressed toward the suction region 273 by the atmospheric pressure just as much as the depressurized amount, whereby the lower wafer WL is drawn and held by the lower chuck 231.
In this case, the pins 271 are uniform in height, which makes it possible to reduce the flatness of the upper surface of the lower chuck 231. Since the interval of the adjoining pins 271 is appropriate, it is possible to restrain particles from existing on the upper surface of the lower chuck 231 even if particles exist within the processing vessel 190. By making the upper surface of the lower chuck 231 flat (by reducing the flatness of the upper surface of the lower chuck 231) in this manner, it is possible to suppress the vertical distortion of the lower wafer WL held by the lower chuck 231. Since the rear surface WL2 of the lower wafer WL is supported by the pins 271, the lower wafer WL is easily separated from the lower chuck 231 upon releasing the vacuum-suction applied to the lower wafer WL by the lower chuck 231.
Through-holes 277 extending through the body portion 270 in the thickness direction thereof are formed, e.g., at three points, in the vicinity of the center of the body portion 270. Lift pins (not shown) existing below the lower chuck holding unit 235 are inserted into the through-holes 277.
As shown in
As shown in
As shown in
As shown in
Next, a method of joining the wafers WU and WL using the joining system 1 configured as indicated above will be described.
First, the cassette CU with a plurality of upper wafers WU, a cassette CL with a plurality of lower wafers WL, and an empty cassette CT are mounted on a specified cassette mounting board 11 of the carry-in/carry-out station 2. Thereafter, the upper wafer WU within the cassette CU is taken out by the wafer transfer unit 22 and is transferred to the transition unit 50 of the third processing block G3 of the processing station 3.
Subsequently, the upper wafer WU is transferred to the surface modification device 30 of the first processing block G1 by the wafer transfer unit 61. The upper wafer WU transferred to the surface modification device 30 is delivered to and mounted on the upper surface of the mounting table 110 by the wafer transfer unit 61. Thereafter, the wafer transfer unit 61 is retracted from the surface modification device 30 and the gate valve 102 is closed. The upper wafer WU mounted on the mounting table 110 is maintained at a predetermined temperature, e.g., 25 degree C. to 30 degree C. by the temperature adjusting mechanism 112.
Thereafter, the suction unit 104 is operated to depressurize the internal atmosphere of the processing vessel 100 to a predetermined vacuum degree, e.g., 67 Pa to 333 Pa (0.5 Torr to 2.5 Torr) through the suction port 103. Then, the internal atmosphere of the processing vessel 100 is kept at the predetermined vacuum degree during the below-mentioned processing of the upper wafer WU.
Thereafter, an oxygen gas is supplied from the gas supply pipe 130 toward the plasma generation region R1 defined within the processing vessel 100. Microwaves of, e.g., 2.45 GHz, are irradiated from the radial line slot antenna 120 toward the plasma generation region R1. Due to the irradiation of the microwaves, the oxygen gas existing within the plasma generation region R1 is excited into plasma. For example, the oxygen gas is ionized. At this time, the microwaves moving downward are reflected by the ion passing structural body 140 to stay within the plasma generation region R1. As a result, high-density plasma is generated within the plasma generation region R1.
Subsequently, a predetermined voltage is applied to the electrodes 141 and 142 of the ion passing structural body 140 by the power supply 145. Thus, only the oxygen ions generated in the plasma generation region R1 are introduced by the electrodes 141 and 142 into the processing region R2 through the openings 144 of the ion passing structural body 140.
At this time, the voltage applied to between the electrodes 141 and 142 is controlled by the control unit 300 to thereby control the energy given to the oxygen ions which pass through the electrodes 141 and 142. The energy given to the oxygen ions is set high enough to cut the double bonds of SiO2 of the front surface WU1 of the upper wafer WU to obtain SiO having a single bond, but small enough not to cause damage in the front surface WU1.
At this time, the current value of an electric current flowing between the electrodes 141 and 142 is measured by the ammeter 146. The amount of the oxygen ions passing through the ion passing structural body 140 can be grasped based on the current value thus measured. Pursuant to the passing amount of the oxygen ions thus grasped, the control unit 300 controls different parameters, such as the amount of the oxygen gas supplied from the gas supply pipe 130, the voltage applied to between the electrodes 141 and 142, and the like, so that the passing amount of the oxygen ions can become a predetermined value.
Thereafter, the oxygen ions introduced into the processing region R2 are irradiated on and implanted into the front surface WU1 of the upper wafer WU mounted on the mounting table 110. By the oxygen ions thus irradiated, the double bonds of SiO2 of the front surface WU1 of the upper wafer WU are cut to obtain SiO having a single bond. Since the oxygen ions are used in modifying the front surface WU1, the oxygen ions irradiated on the front surface WU1 of the upper wafer WU themselves make contribution to the bonding of SiO. In this way, the front surface WU1 of the upper wafer WU is modified (Operation S1 in
At this time, the ion ammeter 111 measures the current value of an ion current generated by the oxygen ions irradiated on the front surface WU1 of the upper wafer WU. The irradiation amount of the oxygen ions irradiated on the front surface WU1 of the upper wafer WU can be grasped based on the current value thus measured. Pursuant to the irradiation amount of the oxygen ions thus grasped, the control unit 300 controls different parameters, such as the amount of the oxygen gas supplied from the gas supply pipe 130, the voltage applied to between the electrodes 141 and 142, and the like, so that the irradiation amount of the oxygen ions can become a predetermined value.
Then, the upper wafer WU is transferred to the surface hydrophilization device 40 of the second processing block G2 by the wafer transfer unit 61. The upper wafer WU transferred to the surface hydrophilization device 40 is delivered from the wafer transfer unit 61 to the spin chuck 160 and are drawn and held by the spin chuck 160.
Subsequently, the pure water nozzle 173 of the standby section 175 is moved to above the central portion of the upper wafer WU by the nozzle arm 171. The scrub cleaning tool 180 is moved to above the upper wafer WU by the scrub arm 172. Thereafter, pure water is supplied from the pure water nozzle 173 onto the upper wafer WU while rotating the upper wafer WU by the spin chuck 160. Thus, hydroxyl groups (silanol groups) adhere to the front surface WU1 of the upper wafer WU modified by the surface modification device 30, whereby the front surface WU1 is hydrophilized. The front surface WU1 of the upper wafer WU is cleaned by the scrub cleaning tool 180 and the pure water supplied from the pure water nozzle 173 (Operation S2 in
Next, the upper wafer WU is transferred to the joining device 41 of the second processing block G2 by the wafer transfer unit 61. In the joining device 41, the upper wafer WU is transferred to the position adjusting mechanism 210 by the transfer mechanism 201 via the transition 200. Then, the horizontal orientation of the upper wafer WU is adjusted by the position adjusting mechanism 210 (Operation S3 in
Thereafter, the upper wafer WU is transferred from the position adjusting mechanism 210 to the holder arm 221 of the inverting mechanism 220. Subsequently, in the transfer region T1, the holder arm 221 is inverted such that the front and rear surfaces of the upper wafer WU are turned upside down (Operation S4 in
Subsequently, the holder arm 221 of the inverting mechanism 220 is rotated about the first drive unit 224 and is moved below the upper chuck 230. Then, the upper wafer WU is transferred from the inverting mechanism 220 to the upper chuck 230. The rear surface WU2 of the upper wafer WU is drawn and held by the upper chuck 230 (Operation S5 in
While Operations S1 to S5 described above are being performed with respect to the upper wafer WU, the lower wafer WL is processed following the processing of the upper wafer WU. First, the lower wafer WL is taken out of the cassette CL by the wafer transfer unit 22 and is transferred to the transition unit 50 of the processing station 3.
Subsequently, the lower wafer WL is transferred by the wafer transfer unit 61 to the surface modification device 30 where the front surface WL1 of the lower wafer WL is modified (Operation S6 in
Thereafter, the lower wafer WL is transferred by the wafer transfer unit 61 to the surface hydrophilization device 40 where the front surface WL1 of the lower wafer WL is hydrophilized and cleaned (Operation S7 in
Thereafter, the lower wafer WL is transferred to the joining device 41 by the wafer transfer unit 61. In the joining device 41, the lower wafer WL is transferred to the position adjusting mechanism 210 by the wafer transfer mechanism 201 via the transition 200. In the position adjusting mechanism 210, the horizontal orientation of the lower wafer WL is adjusted (Operation S8 in
Thereafter, the lower wafer WL is transferred by the wafer transfer mechanism 201 to the lower chuck 231 and is drawn and held by the lower chuck 231 (Operation S9 in
Then, the horizontal positions of the upper wafer WU held by the upper chuck 230 and the lower wafer WL held by the lower chuck 231 are adjusted. As shown in
In addition, the horizontal orientations of the wafers WU and WL are adjusted by the position adjusting mechanism 210 in Operations S3 and S8. The fine adjustment of the horizontal orientations is performed in Operation S10. In Operation S10 of the present embodiment, the predetermined patterns formed on the wafers WU and WL are used as the reference points A and B. However, other reference points may be used. As an example, the outer peripheral portions and the notch portions of the wafers WU and WL may be used as the reference points.
Thereafter, as shown in
Thereafter, as shown in
Thus, joining begins to occur between the central portions of the upper and lower wafers WU and WL pressed against each other (see a thick line indicated in
Thereafter, as shown in
Thereafter, as shown in
The superposed wafer WT obtained by joining the upper wafer WU and the lower wafer WL is transferred to the transition unit 51 by the wafer transfer unit 61 and is then transferred to the cassette CT of the specified cassette mounting board 11 by the wafer transfer unit 22 of the carry-in/carry-out station 2. In this way, a series of joining processes for the wafers WU and WL is finished.
According to the embodiment described above, when the upper wafer WU is held by the upper chuck 230 in the joining device 41, the outer periphery portion of the rear surface WU2 of the upper wafer WU is supported by the outer wall portion 242, and the inner area of the rear surface WU2 of the upper wafer WU is supported by the pins 241 in a contact state. The suction region 243 is vacuum-sucked such that the upper wafer WU is held by the upper chuck 230. In this case, the pins 241 are uniform in height, which makes it possible to reduce the flatness of the lower surface of the upper chuck 230. By making the lower surface of the upper chuck 230 flat (by reducing the flatness of the lower surface of the upper chuck 230) in this manner, it is possible to suppress the vertical distortion of the upper wafer WU held by the upper chuck 230.
Similarly, when the lower wafer WL is held by the lower chuck 231, the pins 271 are kept uniform in height, which makes it possible to reduce the flatness of the upper surface of the lower chuck 231. Since the interval of the adjoining pins 271 is appropriately adjusted, it is possible to restrain particles from existing on the upper surface of the lower chuck 231 even if particles exist within the processing vessel 190. By making the upper surface of the lower chuck 231 flat (by reducing the flatness of the upper surface of the lower chuck 231) in this manner, it is possible to suppress the vertical distortion of the lower wafer WL held by the lower chuck 231.
Inasmuch as the vertical distortion of the upper wafer WU and the lower wafer WL can be suppressed in the aforementioned manner, it is possible to suppress the vertical distortion of the joined superposed wafer WT when the upper wafer WU and the lower wafer WL are joined together.
Since the lower surface of the upper chuck 230 and the upper surface of the lower chuck 231 can be made flat, it is possible to have the upper chuck 230 and the lower chuck 231 positioned closer to each other when the upper wafer WU and the lower wafer WL are joined together. The joining of the upper wafer WU and the lower wafer WL is expanded in an approximately true circle pattern, which makes it possible to appropriately perform the joining of the upper wafer WU and the lower wafer WL.
Owing to the fact that the rear surface WU2 of the upper wafer WU is supported by the pins 241, the upper wafer WU is easily separated from the upper chuck 230 upon releasing the vacuum suction of the upper wafer WU performed by the upper chuck 230. Similarly, the rear surface WL2 of the lower wafer WL is supported by the pins 271. Therefore, the lower wafer WL is easily separated from the lower chuck 231 upon releasing the vacuum suction of the lower wafer WL performed by the lower chuck 231.
In the present embodiment, the interval of the adjoining pins 241 of the upper chuck 230 is larger than the interval of the adjoining pins 271 of the lower chuck 231. This is because it is only necessary for the upper chuck 230 to make the upper wafer WU flat and because it is not necessary to make the interval of the pins 241 narrow. However, the interval of the pins 241 and the interval of the pins 271 may be set arbitrarily.
Since the guide members 280 are installed in the outer periphery portion of the lower chuck 231, it is possible to prevent the wafers WU and WL and the superposed wafer WT from jutting out or sliding down from the lower chuck 231. Moreover, the guide members 280 have a spring structure in which the guide pin 282 can move in the vertical direction. Therefore, even if the upper wafer WU gets out of alignment and makes contact with the guide pin 282 during the joining process of the upper wafer WU and the lower wafer WL, the guide pin 282 is moved into the casing 281. It is therefore possible to prevent the upper wafer WU from being damaged.
The joining system 1 includes not only the joining device 41 but also the surface modification device 30 configured to modify the front surfaces WU1 and WL1 of the wafers WU and WL and the surface hydrophilization device 40 configured to hydrophilize and clean the front surfaces WU1 and WL1. Thus, the joining of the wafers WU and WL can be efficiently performed within a single system. It is therefore possible to enhance the throughput of the wafer joining process.
In the joining device 41 of the aforementioned embodiment, as shown in
First suction ports 244a and second suction ports 244b are formed in the first suction region 243a and the second suction region 243b, respectively. First suction pipes 245a and second suction pipes 245b communicating with different vacuum pumps 246a and 246b are connected to the first suction ports 244a and the second suction ports 244b, respectively. In this way, the upper chuck 230 is configured such that the upper wafer WU can be vacuum-sucked in each of the first suction region 243a and the second suction region 243b.
In this case, for example, when the upper wafer WU is drawn and held by the upper chuck 230 with the outer periphery portion of the upper wafer WU bent more downward than the central portion thereof, the upper chuck 230 first draws the upper wafer WU in the first suction region 243a, thereby drawing and holding the upper wafer WU. Thereafter, the upper chuck 230 draws the upper wafer WU in the second suction region 243b, eventually drawing and holding the upper wafer WU. Thus, the upper wafer WU is appropriately held by the upper chuck 230.
As another example, when the upper wafer WU is drawn and held by the upper chuck 230 with the central portion of the upper wafer WU bent more downward than the outer periphery portion thereof, the upper chuck 230 first draws the upper wafer WU in both the first suction region 243a and the second suction region 243b, thereby drawing and holding the upper wafer WU. Thereafter, the upper chuck 230 stops the drawing of the upper wafer WU in the second suction region 243b while continuing to draw the upper wafer WU in the first suction region 243a. Thus, the upper wafer WU is appropriately held by the upper chuck 230.
As set forth above, the suction region 243 is divided by the partition wall portion 400 so that the upper wafer WU can be vacuum-sucked in each of the first suction region 243a and the second suction region 243b. Therefore, regardless of the shape of the upper wafer WU held by the upper chuck 230, it is possible for the upper chuck 230 to appropriately draw and hold the upper wafer WU.
Just like the partition wall portion 400 of the upper chuck 230, as shown in
First suction ports 274a and second suction ports 274b are formed in the first suction region 273a and the second suction region 273b, respectively. First suction pipes 275a and second suction pipes 275b communicating with different vacuum pumps 276a and 276b are connected to the first suction ports 274a and the second suction ports 274b, respectively. In this way, the lower chuck 231 is configured such that the lower wafer WL can be vacuum-sucked in each of the first suction region 273a and the second suction region 273b.
In this case, for example, when the lower wafer WL is drawn and held by the lower chuck 231 with the outer periphery portion of the lower wafer WL bent more upward than the central portion thereof, the lower chuck 231 first draws the lower wafer WL in the first suction region 273a, thereby drawing and holding the lower wafer WL. Thereafter, the lower chuck 231 draws the lower wafer WL in the second suction region 273b, eventually drawing and holding the lower wafer WL. Thus, the lower wafer WL is appropriately held by the lower chuck 231.
As another example, when the lower wafer WL is drawn and held by the lower chuck 231 with the central portion of the lower wafer WL bent more upward than the outer periphery portion thereof, the lower chuck 231 first draws the lower wafer WL in both the first suction region 273a and the second suction region 273b, thereby drawing and holding the lower wafer WL. Thereafter, the lower chuck 231 stops the drawing of the lower wafer WL in the second suction region 273b while continuing to draw the lower wafer WL in the first suction region 273a. Thus, the lower wafer WL is appropriately held by the lower chuck 231.
As mentioned above, the suction region 273 is divided by the partition wall portion 410 so that the lower wafer WL can be vacuum-sucked in each of the first suction region 273a and the second suction region 273b. Therefore, regardless of the shape of the lower wafer WL held by the lower chuck 231, it is possible for the lower chuck 231 to appropriately draw and hold the lower wafer WL.
The arrangement of the partition wall portion 400 or 410 is not limited to that of the aforementioned embodiment but may be set arbitrarily. The number of the suction region 243 or 273 divided by the partition wall portion 400 or 410 is not limited to that of the aforementioned embodiment but may be three or more. Earnest investigation conducted by the inventors reveals that the wafer WU or WL can be appropriately held only if the suction region 243 or 273 is divided into two regions. The number of the partition wall portion 400 or 410 is set small in some embodiments, with a view to reduce the area on which the wafer WU or WL is supported by the partition wall portion 400 or 410 and to reduce the flatness of the wafer WU or WL.
In the joining device 41 of the aforementioned embodiment, as shown in
In this case, when the upper wafer WU is vacuum-sucked in the suction region 243, the flow velocity in the first suction region 243a where the protrusion portion 420 is not formed can be made smaller than the flow velocity in the second suction region 243b where the protrusion portion 420 is formed. Thus, even when the upper wafer WU is drawn and held by the upper chuck 230 with the outer periphery portion of the upper wafer WU bent more downward than the central portion thereof, it is possible to vacuum-suck the outer periphery portion of the upper wafer WU more strongly than the central portion thereof and to appropriately draw and hold the upper wafer WU with the upper chuck 230.
Similarly, as shown in
In this case, the flow velocity in the first suction region 273a where the protrusion portion 430 is not formed can be made smaller than the flow velocity in the second suction region 273b where the protrusion portion 430 is formed. Thus, even when the lower wafer WL is drawn and held by the lower chuck 231 with the outer periphery portion of the lower wafer WL bent more upward than the central portion thereof, it is possible to vacuum-suck the outer periphery portion of the lower wafer WL more strongly than the central portion thereof and to appropriately draw and hold the lower wafer WL with the lower chuck 231.
By forming the protrusion portion 420 or 430 on the chuck 230 or 231 in this manner, it is possible to control the flow velocity in the suction region 243 or 273 and to appropriately draw and hold the wafer WU or WL.
In the present embodiment, the upper chuck 230 is preferably made as light as possible in order to restrain the upper chuck 230 from being vibrated during the joining of the wafers WU and WL. For example, the upper chuck 230 can be made lightweight by partially cutting the upper surface of the upper chuck 230 and consequently forming grooves.
As described with respect of the foregoing embodiment, it is possible to suppress the vertical distortion of the joined superposed wafer WT. Such a technology of suppressing the vertical distortion is useful in, e.g., CMOS (Complementary Metal Oxide Semiconductor) sensor wafers or BSI (Back Side Illumination) model wafers.
In the aforementioned embodiment, the lower chuck 231 can be moved up and down in the vertical direction and can be moved in the horizontal direction by the lower chuck drive unit 237. Alternatively, the upper chuck 230 may be movable in the vertical direction. Moreover, both the upper chuck 230 and the lower chuck 231 may be configured such that they can be moved up and down in the vertical direction and can be moved in the horizontal direction.
In the joining system 1 of the aforementioned embodiment, the joined superposed wafer WT may be heated to a predetermined temperature after the wafers WU and WL are joined together by the joining device 41. By subjecting the superposed wafer WT to such a heating process, it is possible to firmly couple the joining interfacial surfaces together.
According to the present disclosure, it is possible to suppress a vertical distortion of a joined superposed substrate by appropriately holding substrates when the substrates are joined together.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosures. Indeed, the novel devices and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures. The present disclosure can also be applied to a case where the substrate is not a wafer but other substrate such as a FPD (Flat Panel Display) or a mask reticle for photo masks.
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2013-012326 | Jan 2013 | JP | national |
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