Plasma treatment appatus, wafer to wafer bonding system and wafer to wafer bonding method

Abstract

A plasma processing device includes a load lock chamber capable of switching between an atmospheric pressure state and a vacuum pressure state, and a substrate processing device for transferring a substrate to the load lock chamber and performing plasma processing on the surface of the substrate in a plasma chamber in a vacuum pressure state. The substrate processing device includes a substrate support member disposed within the plasma chamber and for supporting a substrate from the load lock chamber, a plasma gas supply member for supplying plasma gas into the plasma chamber, a steam supply member for supplying steam into the plasma chamber, and a plasma generator for generating plasma within the plasma chamber.

Description

Technology Field

[0001] The present invention relates to a plasma treatment apparatus, a wafer bonding system, and a wafer bonding apparatus. More specifically, the present invention relates to a plasma treatment apparatus for performing plasma treatment on a wafer surface prior to a wafer bonding process for bonding wafers together, a wafer bonding system including the same, and a wafer bonding method using the same. Background Technology

[0002] In the production of products such as CIS (CMOS Image Sensor) and HBM (High Bandwidth Memory), bonding two wafers together can overcome the limitations associated with semiconductor linewidth miniaturization, improve performance through the application of 3D interconnection structures, and increase yield per wafer. This wafer bonding process consists of a plasma activation step, a hydration step, a wafer alignment step, a wafer bonding step, and an annealing step. The plasma processing device in which the plasma activation step is performed can increase productivity by using a load lock chamber to maintain the plasma processing chamber in a constant vacuum state. However, there is a problem in that the bonding strength between wafers decreases due to the constant vacuum maintenance of the plasma chamber. The problem to be solved

[0003] One objective of the present invention is to provide a plasma processing apparatus capable of improving the bonding strength of a wafer and suppressing changes over time.

[0004] Another objective of the present invention is to provide a wafer bonding system including the plasma processing apparatus described above.

[0005] Another objective of the present invention is to provide a wafer bonding method using the wafer bonding system described above. means of solving the problem

[0006] A plasma processing apparatus according to exemplary embodiments for achieving one objective of the present invention comprises a load lock chamber switchable between an atmospheric pressure state and a vacuum pressure state, and a substrate processing apparatus for transferring a substrate to the load lock chamber and performing plasma processing on the surface of the substrate in a plasma chamber in a vacuum pressure state. The substrate processing apparatus comprises a substrate support member disposed within the plasma chamber and for supporting a substrate from the load lock chamber, a plasma gas supply member for supplying plasma gas into the plasma chamber, a steam supply member for supplying steam into the plasma chamber, and a plasma generator for generating plasma within the plasma chamber.

[0007] A plasma processing apparatus according to exemplary embodiments for achieving one objective of the present invention comprises: a substrate transfer device for transferring a substrate in an atmospheric pressure state; a substrate processing device for performing plasma processing on the surface of the substrate in a plasma chamber in a vacuum pressure state; a load lock chamber capable of transferring the substrate between the substrate transfer device and the substrate processing device and switching between an atmospheric pressure state and a vacuum pressure state; a vacuum transfer module for transferring the substrate between the load lock chamber and the plasma chamber in a vacuum pressure state; and a steam supply unit for supplying steam into the plasma chamber.

[0008] A wafer bonding system according to exemplary embodiments for achieving another objective of the present invention comprises: an index module for loading and unloading wafers; a substrate transfer device for transferring the wafers from the index module under atmospheric pressure; a substrate processing device for performing plasma treatment on the wafer surface in a plasma chamber under vacuum pressure; a load lock chamber capable of transferring the wafer between the substrate transfer device and the substrate processing device and switching between atmospheric pressure and vacuum pressure states; a vacuum transfer module for transferring the wafer between the load lock chamber and the plasma chamber under vacuum pressure; a cleaning device for cleaning the wafer surface plasma-treated by the substrate processing device; and a wafer bonding device for bonding the cleaned wafers together. The substrate processing device includes a steam supply unit for supplying steam into the plasma chamber.

[0009] In a wafer bonding method according to exemplary embodiments for achieving another objective of the present invention, a wafer is introduced into a load lock chamber under atmospheric pressure. The load lock chamber is switched to a vacuum pressure state. Water vapor is supplied into a plasma chamber connected to the load lock chamber. The wafer is loaded into the plasma chamber. Plasma is generated within the plasma chamber to perform plasma treatment on the wafer. The wafer is unloaded from the plasma chamber to the load lock chamber. Effects of the invention

[0010] According to exemplary embodiments, a plasma processing device of a wafer bonding system comprises a load lock chamber switchable between an atmospheric pressure state and a vacuum pressure state, and a substrate processing device for performing substrate transfer with said load lock chamber and performing plasma processing on the surface of said substrate in a plasma chamber in a vacuum pressure state. The substrate processing device comprises a steam supply unit for supplying steam into said plasma chamber.

[0011] The above-mentioned steam supply unit can supply steam into the plasma chamber before or when plasma is generated within the plasma chamber. Therefore, even if the plasma chamber is maintained in a constant vacuum state, the moisture inside the plasma chamber can be maintained above a certain level to increase and maintain the generation amount of OH radicals. Accordingly, the bonding strength between the plasma-treated wafers can be improved, and by suppressing changes in the interior of the plasma chamber over time, the decrease in bonding strength between wafers over time can be prevented.

[0012] However, the effects of the present invention are not limited to the effects mentioned above and may be extended in various ways without departing from the spirit and scope of the present invention. Brief explanation of the drawing

[0013] FIG. 1 is a block diagram showing a wafer bonding system according to exemplary embodiments. Figure 2 is a cross-sectional view showing the plasma processing apparatus of Figure 1. Figure 3 is a cross-sectional view showing the wafer bonding device of Figure 1. FIG. 4 is a block diagram showing a substrate processing apparatus according to exemplary embodiments. Figure 5 is a block diagram showing the gas supply section of Figure 4. Figure 6 is a drawing showing the interior of a plasma chamber where steam is supplied by the gas supply unit of Figure 5. Figure 7 is a diagram showing the state in which water vapor supplied by the gas supply unit of Figure 5 is dissociated within the plasma chamber. Figure 8 is a diagram showing the state in which plasma gas and water vapor supplied by the gas supply unit of Figure 5 are dissociated within the plasma chamber. FIG. 9 is a flowchart illustrating a wafer bonding method according to exemplary embodiments. Figure 10 is a diagram showing the wafer bonding method of Figure 9. Figure 11 is a flowchart showing the detailed steps of the plasma treatment step of Figure 9. FIGS. 12 and FIGS. 13 are timing diagrams illustrating plasma treatment steps according to exemplary embodiments. Specific details for implementing the invention

[0014] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings.

[0015] FIG. 1 is a block diagram showing a wafer bonding system according to exemplary embodiments. FIG. 2 is a cross-sectional view showing a plasma processing apparatus of FIG. 1. FIG. 3 is a cross-sectional view showing a wafer bonding apparatus of FIG. 1. FIG. 2 is a cross-sectional view cut along the AA' line of FIG. 1.

[0016] Referring to FIGS. 1 to 3, the wafer bonding system (10) may include an index module (20) for loading and unloading wafers, and a process module (22) disposed on one side of the index module (20) for bonding the wafers together. The process module (22) may include a plasma processing device (70), a cleaning device (80), and a wafer bonding device (90). Additionally, the process module (22) may further include an alignment device (50). The process module (22) is formed as a rectangular room having an internal space, and can maintain a cleanliness level within a preset range by forming a space in which fine dust and foreign substances are blocked.

[0017] In exemplary embodiments, the index module (20) may include a rectangular cassette stage (30) and an indexer robot (40). The cassette stage (30) may provide a space for storing wafers. A plurality of support plates (32) may be arranged along the long side direction (Y direction) of the cassette stage (30). Wafer carriers (FOUP) (C) containing a plurality of wafers may be supported on each of the support plates (32). The wafers contained in the carrier (C) may be transferred into the process module (22) by the transfer robot (40).

[0018] For example, two carriers (C) may be placed on a cassette stage (30). First and second wafers that are bonded to each other are stored in the first and second carriers (C), and bonded wafers may be stored in one of the two carriers (C). Here, the first wafer may be an upper wafer and the second wafer may be a lower wafer.

[0019] The first wafer may be a wafer on which circuits for an image sensor chip are formed, and the second wafer may be a wafer on which light receiving sensors for an image sensor chip are formed. Alternatively, the first wafer may be a wafer on which circuits for a semiconductor package, such as HBM, are formed, and the second wafer may be a wafer on which memories for the semiconductor package are formed.

[0020] In exemplary embodiments, the alignment device (50) can align the wafer (W) by detecting the flat portion (P) (or notch) of the wafer (W). The alignment device (50) may include a position adjustment mechanism (52) comprising a base that supports the wafer (W), a rotating portion that rotates the base, and a base inversion portion that inverts the base. The wafer aligned by the alignment device (50) may be transferred to a plasma processing device (70), a cleaning device (80), or a wafer bonding device (90) by a transfer robot (60, 62) as a substrate transfer device.

[0021] Although not illustrated in the drawing, the alignment device (50) may further include a loading plate for temporarily loading a wafer returned by an indexer robot (22) or a transfer robot (60). Additionally, the loading plate may be rotated by an inversion mechanism to invert the wafer adsorbed on the loading plate.

[0022] The first transfer robot (60) can move within a transfer area within the process module (22) and transfer the wafer between an alignment device (50), a plasma processing device (70), a cleaning device (80), and a wafer bonding device (90) adjacent to the transfer area. The transfer of the wafer by the first transfer robot (60) can be performed in an atmospheric pressure atmosphere. For example, the atmospheric pressure atmosphere may include atmospheric pressure or a pressure range close to atmospheric pressure (±10 kPa). The first transfer robot within the transfer area can function as an atmospheric transfer module.

[0023] In exemplary embodiments, the plasma processing device (70) may include a substrate processing device (100), a vacuum transfer module (200), and a load lock chamber (300). As described below, the plasma processing device (70) can perform plasma processing on the wafer surface by using the load lock chamber (300) to maintain the inside of the plasma chamber (110) of the substrate processing device (100) in a vacuum state at all times.

[0024] The load lock chamber (300) can serve as an interfacing chamber between the atmospheric transfer module and the vacuum transfer module (200). The load lock chamber (300) can be controlled to allow selective transfer of the wafer from the atmospheric transfer module to the vacuum transfer module (200).

[0025] At least one substrate plate (320) for supporting the wafer may be disposed within the load lock chamber (300). The substrate plate (320) may support the wafer. For example, the substrate plate (320) may load a first wafer or a second wafer loaded from the first transfer robot (60) into the plasma chamber (110) and load a first wafer or a second wafer unloaded from the plasma chamber (110) to the first transfer robot (60).

[0026] As illustrated in FIG. 2, the first vacuum pump (318) can be connected to the load lock chamber (300) by the first exhaust pipe (314). For example, the first vacuum pump (318) may include a dry vacuum pump. When the first gate valve (312) and the second gate valve (212) are closed and the valve (316) installed in the first exhaust pipe (314) is opened, the interior of the load lock chamber (300) can be depressurized to a depressurized atmosphere. At this time, the first vacuum pump (318) is always operated, and the interior of the load lock chamber (300) can be formed into a depressurized atmosphere through the on / off control of the valve (316). Meanwhile, in order to switch the interior of the load lock chamber (300) to an atmospheric atmosphere, nitrogen or clean dry air (CDA) can be supplied to the interior of the load lock chamber (300) to form an internal pressure of atmospheric pressure and the first gate valve (312) can be opened. Accordingly, the interior of the load lock chamber (300) is connected to the conveying area under an atmospheric atmosphere, so that the interior of the load lock chamber (300) can become an atmospheric atmosphere. Accordingly, the load lock chamber (300) can be switched between an atmospheric pressure atmosphere and a reduced pressure atmosphere.

[0027] A transfer device (220) for transferring the wafer may be disposed within the vacuum transfer module (200). For example, the transfer device (220) may include a transfer arm that is movable in the vertical and horizontal directions and rotatable about a vertical axis.

[0028] The second vacuum pump (218) may be connected to the vacuum transfer module (200) by the second exhaust pipe (214). For example, the second vacuum pump (218) may include a dry vacuum pump. When the second vacuum pump (218) is operated and the valve (216) installed in the second exhaust pipe (214) is opened, the interior of the vacuum transfer module (200) may be depressurized to a vacuum atmosphere. When the load lock chamber (300) is under a depressurized atmosphere, the second gate valve (212) may be opened. When the plasma chamber (110) is under a vacuum atmosphere, the third gate valve (112) may be opened. Thus, the transfer device (220) within the vacuum transfer module (200) can transfer a wafer between the load lock chamber (300) and the plasma chamber (110) under a vacuum atmosphere.

[0029] As described below, the substrate processing device (100) can perform plasma processing on a substrate surface, such as a semiconductor wafer (W) placed in a plasma chamber (110), to form a dangling bond on the substrate surface. A third vacuum pump (118) can be connected to the plasma chamber (110) by a third exhaust pipe (115). For example, the third vacuum pump (118) may include a dry vacuum pump. When the third vacuum pump (118) is operated, the interior of the plasma chamber (110) can be depressurized to a vacuum atmosphere. The plasma chamber (110), like the vacuum transfer module (200), can be maintained in a vacuum atmosphere at all times.

[0030] In the substrate processing device (100), plasma gas is excited and plasma-formed under the vacuum atmosphere to generate ions and active species. Then, by irradiating the bonding surface of the wafer with these ions and active species, the bonding surface can be plasma-treated and modified.

[0031] The internal volume of the load lock chamber (300) may be set smaller than the internal volume of the vacuum transfer module (200) or the plasma chamber (110), but is not limited thereto.

[0032] Referring again to FIG. 1, the first wafer or the second wafer, which has been plasma-treated by the plasma treatment device (70), can be loaded into the cleaning device (80) by the first transfer robot (60).

[0033] The cleaning device (80) can clean the surface of a wafer that has been plasma-treated by the plasma treatment device (70). The cleaning device (80) can clean the surface of the wafer using the DI water by including a nozzle for spraying DI water and a support member that can support and rotate the wafer. The DI water not only cleans the surface of the wafer but also facilitates the bonding of the wafer by allowing -OH groups and water molecules to bond well to the surface of the wafer.

[0034] The cleaning device (80) may be positioned adjacent to the plasma treatment device (70). Alternatively, the cleaning device (80) may be positioned stacked on top of the plasma treatment device (70). It will be understood that the arrangement of the plasma treatment device and the cleaning device is exemplary and is not limited thereto.

[0035] The first wafer or the second wafer, which has been rinsed by the cleaning device (80), can be loaded into the wafer bonding device (90) by the first transfer robot (60) and the second transfer robot (62).

[0036] As illustrated in FIG. 3, the wafer bonding device (90) may include a lower chuck structure and an upper chuck structure. The upper chuck structure may include an upper stage (410) for fixing a first wafer (W1), and the lower chuck structure may include a lower stage (400) for fixing a second wafer (W2).

[0037] The first wafer (W1) can be vacuum-adsorbed by pressure holes (412) formed in the upper stage (410). The pressure holes (412) of the upper stage (410) can be divided into several regions and controlled independently of each other. For example, the pressure holes can be formed in first to third regions arranged sequentially in a radial direction from the center. The first region corresponds to the center region of the upper stage (410), the third region corresponds to the peripheral region of the upper stage (410), and the second region corresponds to an intermediate region between the center region and the peripheral region. The second wafer (W2) can be vacuum-adsorbed by pressure holes (402) formed in the lower stage (400). Similar to the pressure holes of the upper stage, the pressure holes of the lower stage (400) can also be divided into several regions and controlled independently of each other.

[0038] The upper stage (410) can be fixedly installed on the upper frame (422). The lower stage (400) can be positioned to face the upper stage (410). The lower stage (400) can be installed to be raised and lowered by a lifting rod (421). Accordingly, the second wafer (W2) on the lower stage (400) can be moved toward the first wafer (W1) on the upper stage (410). Additionally, the lower stage (400) can be installed to allow linear movement and rotational movement, thereby adjusting its relative position to the upper stage (410).

[0039] The wafer bonding device (90) may include a push rod (430) for pressing a central region of the first wafer (W1). The push rod (430) may be installed to be movable through the upper stage (410). Alternatively, the wafer bonding device (90) may include another push rod for pressing a central region of the second wafer (W2) together with or instead of the push rod (430).

[0040] When the first and second wafers (W1, W2) are fixed to the upper stage (410) and the lower stage (400), respectively, the wafer adsorption process can be performed.

[0041] First, the first wafer (W1) can be adsorbed to the upper stage (410) with equal pressure across the periphery and center of the upper surface, and the second wafer (W2) can be adsorbed to the lower stage (400) with equal pressure across the periphery and center of the lower surface.

[0042] Next, the push rod (430) can descend to apply pressure to the center portion of the first wafer (W1). Accordingly, the center portion of the first wafer (W1) protrudes further downward than the periphery, so that the first wafer (W1) can be curved downward in a convex manner. At this time, the vacuum pressure of the pressure relief holes formed in the first region is removed, and the vacuum pressure of the pressure relief holes formed in the second and third regions is maintained, so that only the periphery of the first wafer (W1) can be vacuum-adsorbed by the pressure relief holes (412) formed in the upper stage (410).

[0043] With the first wafer (W1) deformed convexly downward, the central part of the first wafer (W1) first comes into contact with the second wafer (W2) and gradually comes into contact with it outward.

[0044] Next, by removing the vacuum pressure in the pressure relief holes (412) of the upper stage (410), the first wafer (W1) and the second wafer (W2) can be bonded together.

[0045] A wafer bonding system (10) can be used to bond wafers together, but is not limited thereto. For example, the wafer bonding system can be used to bond a die to a wafer (die-to-wafer bonding) or to bond a die to a die (die-to-die bonding).

[0046] Below, the plasma processing apparatus of FIG. 1 will be described in detail.

[0047] FIG. 4 is a block diagram showing a substrate processing apparatus according to exemplary embodiments. FIG. 5 is a block diagram showing a gas supply unit of FIG. 4. FIG. 4 is a block diagram showing a substrate processing apparatus of FIG. 1.

[0048] Referring to FIGS. 4 and 5, the substrate processing device (100) may include a plasma chamber (110), a substrate stage (120) having a lower electrode, an upper electrode (140), a shower head (160), and a gas supply unit (170).

[0049] In exemplary embodiments, the substrate processing device (100) may be a device for forming a dangling bond on the surface of a substrate, such as a semiconductor wafer (W), placed in an induced coupled plasma (ICP) chamber (110) by irradiating plasma onto the surface of the substrate. However, the plasma generated by the plasma processing device is not limited to induced coupled plasma and may be, for example, capacitive coupled plasma or microwave plasma.

[0050] A plasma chamber (110) may provide a sealed space for performing a plasma processing process on a wafer (W). The plasma chamber (110) may be a cylindrical vacuum chamber. The plasma chamber (110) may be made of a metal such as aluminum or stainless steel. The plasma chamber (110) may include a cover (111) that covers the top of the plasma chamber (110). The cover (111) may seal the top of the plasma chamber (110).

[0051] A third gate valve (112, see FIG. 1) for the entry and exit of a wafer (W) may be installed on the side wall of the plasma chamber (110). Through the third gate valve, the wafer (W) can be loaded onto and unloaded onto the substrate stage.

[0052] An exhaust port (114) is installed at the bottom of the plasma chamber (110), and the exhaust port (114) can be connected to a third vacuum pump (118, see FIG. 2) by a third exhaust pipe (115, see FIG. 2). An exhaust section (116) can be connected to the exhaust port (114). The exhaust section (116) includes an Automatic Pressure Controller (APC) (117) and a turbo molecular pump (TMP) to regulate the pressure of the processing space inside the plasma chamber (110) to a desired vacuum level. The turbo molecular pump is not essential and can be omitted if necessary, in which case only the third vacuum pump may be used. Additionally, process byproducts and residual process gases generated within the plasma chamber (110) can be discharged through the exhaust port (114).

[0053] The substrate stage (120) can support a wafer (W) within a plasma chamber (110). The substrate stage (120) may include a lower electrode on which the wafer is placed.

[0054] The upper electrode (140) may be positioned on the upper outer side of the plasma chamber (110) so as to face the lower electrode. The upper electrode (140) may be positioned on the cover (111). Alternatively, the upper electrode (140) may be formed on the upper side of the shower head (160) or on the upper side of the plasma chamber.

[0055] The upper electrode (140) may include a high-frequency (RF) antenna. The antenna may have a planar coil shape. The cover (111) may include a disc-shaped dielectric window. The dielectric window includes a dielectric material. For example, the dielectric window may include aluminum oxide (Al2O3). The dielectric window may have the function of transmitting power from the antenna into the plasma chamber (110).

[0056] For example, the upper electrode (140) may include coils in a spiral or concentric shape. The coils may generate inductively coupled plasma (P) in the plasma space of the plasma chamber (110). Here, it will be understood that the number, arrangement, etc. of the coils are not limited thereto.

[0057] In exemplary embodiments, the gas supply unit (170) may include a plasma gas supply unit (172) for supplying plasma gas into the plasma chamber (110) and a steam supply unit (174) for supplying steam into the plasma chamber (110). The first gas supply unit (172) and the second gas supply unit (174) are each connected to a shower head (140), and the plasma gas and the steam may be supplied into the plasma chamber (110) through the shower head (140).

[0058] The plasma gas supply unit (172) may include a first plasma gas supply unit for supplying a first plasma gas and a second plasma gas supply unit for supplying a second plasma gas. For example, the first plasma gas may include oxygen (O2) gas, and the second plasma gas may include nitrogen (N2) gas. Additionally, the plasma gas supply unit (172) may further include a third plasma gas supply unit for supplying a third plasma gas, such as argon (Ar) gas.

[0059] As illustrated in FIG. 5, the first plasma gas supply unit may include, as the first plasma gas supply elements, a first plasma gas supply source (180a), a first plasma gas supply line (181a, 183a) connected to the first plasma gas supply source (180a) to supply the first plasma gas into the plasma chamber (110), and a first flow controller (182a) for controlling the supply flow rate of the first plasma gas.

[0060] A first plasma gas source (180a) can supply the first plasma gas. For example, the first plasma gas may include oxygen (O2) gas. The first plasma gas supply lines (181a, 183a) may be connected to the gas introduction path (164) of the shower head (160) inside the plasma chamber (110). The first plasma gas from the first plasma gas source (180a) may be supplied into the plasma chamber (110) through the first plasma gas supply lines (181a, 183a) and the shower head (160). A first flow controller (182a) may control the supply flow rate of the first plasma gas flowing into the plasma chamber (110) through the first plasma gas supply lines (181a, 183a). The first flow controller (182a) may include a mass flow controller (MFC).

[0061] Similarly, the second plasma gas supply unit may include, as the second plasma gas supply elements, a second plasma gas supply source (180b), a second plasma gas supply line (181b, 183b) connected to the second plasma gas supply source (180b) to supply the second plasma gas into the plasma chamber (110), and a second flow controller (182b) for controlling the supply flow rate of the second plasma gas.

[0062] The second plasma gas source (180b) can supply the second plasma gas. For example, the second plasma gas may include nitrogen (N2) gas, but is not limited thereto. The second plasma gas supply lines (181b, 183b) can be connected to the gas introduction path (164) of the shower head (160) inside the plasma chamber (110). The second plasma gas from the second plasma gas source (180b) can be supplied into the plasma chamber (110) through the second plasma gas supply lines (181b, 183b) and the shower head (160). The second flow controller (182b) can control the supply flow rate of the plasma gas flowing into the plasma chamber (110) through the second plasma gas supply lines (181b, 183b). The second flow controller (182b) may include a mass flow controller (MFC).

[0063] Although not illustrated in the drawing, the gas supply unit (170) may further include a pressure regulating gas supply unit for supplying pressure regulating gas. The pressure regulating gas supply unit may include pressure regulating gas supply elements, such as a pressure regulating gas supply source, a pressure regulating gas supply line connected to the pressure regulating gas supply source to supply the pressure regulating gas into the plasma chamber (110), and a flow controller for controlling the supply flow rate of the pressure regulating gas.

[0064] The pressure regulating gas supply source may supply the pressure regulating gas into the plasma chamber (110) to change from a vacuum state to an atmospheric state for maintenance of the chamber. For example, the pressure regulating gas may include a gas such as N2, but is not limited thereto. The pressure regulating gas supply line may be connected to a separate supply line installed on the side wall of the chamber, rather than to the shower head (160) inside the plasma chamber (110). The pressure regulating gas from the pressure regulating gas supply source may be supplied into the plasma chamber (110) through the pressure regulating gas supply line and the supply line.

[0065] The steam supply unit (174) may include the steam supply elements, a steam source (190), a steam supply line (191, 193) connected to the steam source (190) to supply the steam into the plasma chamber (110), and a third flow controller (192) for controlling the supply flow rate of the steam.

[0066] A steam source (190) can supply the steam. For example, the steam source can be configured in various forms such as a bypass method, a bubbler method, or a natural vaporization method. Steam supply lines (191, 193) can be connected to the gas inlet (164) of a shower head (160) inside the plasma chamber (110). The steam from the steam source (190) can be supplied into the plasma chamber (110) through the steam supply lines (191, 193) and the shower head (160). A third flow controller (192) can control the supply flow rate of steam flowing into the plasma chamber (110) through the steam supply lines (191, 193). The third flow controller (192) may include a mass flow controller (MFC).

[0067] The first to third flow controllers (182a, 182b, 192) may be placed inside the gas box (GB). Although it is illustrated that only the flow controllers are installed inside the gas box (GB), valves, regulators, etc. connected before and after the flow controllers may be installed inside the gas box (GB).

[0068] The valves (184a, 184b, 194) may be supply elements for supplying and blocking the plasma gas and the water vapor. As described above, the plasma gas and the water vapor may be supplied into the plasma chamber (110) using a showerhead type, but are not limited thereto, and may be supplied into the plasma chamber (110) using, for example, a gas injection nozzle type or a flow type.

[0069] In exemplary embodiments, the steam supply unit (174) may further include a heater jacket (195) to surround at least a portion of the steam supply line (191) and prevent steam within the steam supply line (191) from condensing. For example, the heater jacket (195) may include a heating pad surrounding the steam supply line (191).

[0070] Additionally, the steam supply unit (174) may further include a temperature sensor (TS) for detecting the temperature of the steam in the steam supply source (190) and a pressure sensor (PS) for detecting the pressure of the steam in the steam supply source (190).

[0071] For example, the pressure inside the plasma chamber (110) may be in a high vacuum state (several mTorr) and the temperature may be 60°C, the pressure inside the steam supply line (191) may be in a low vacuum state and the temperature may be 25°C, and the pressure inside the steam source (190) may be in a low vacuum (about 10 Torr) and the temperature may be 25°C. In this case, if the pressure inside the steam source (190) drops to about 24 Torr or lower, vaporization may occur and steam may be generated from water (DIW). In order to move the generated steam into the plasma chamber (110) without condensation, it may be important to manage the appropriate pressure and temperature of the steam source and the steam supply line.

[0072] To prevent the condensation of the steam, the temperature (T2) of the steam supply line (191) needs to be maintained above the temperature (T1) in the steam source (190). A heater jacket (195) is provided to surround at least a portion of the steam supply line (191) so as to maintain the temperature (T2) of the steam supply line (191) higher than the temperature (T1) in the steam source (190). For more certain prevention of the condensation of the steam, the heater jacket may be provided to surround the entire supply line, including the third flow controller and the valve, as well as the steam supply line.

[0073] A first power supply unit (150) as a plasma generator can apply plasma source power to an upper electrode (140). For example, the first power supply unit (150) may include a source RF power supply (152) and a source RF matching unit (154) as plasma source elements. The source RF power supply (152) can generate a high frequency (RF) signal. The source RF matching unit (154) can control the plasma to be generated using the coils by matching the impedance of the RF signal generated from the source RF power supply (152).

[0074] The second power supply unit (130) as the plasma generator can apply bias source power to the lower electrode. For example, the second power supply unit (130) may include bias elements, such as a bias RF power supply (132) and a bias RF matching unit (134). The lower electrode can attract plasma atoms or ions generated within the plasma chamber (110). The bias RF power supply (132) can generate a high frequency (RF) signal. The bias RF matching unit (132) can match the impedance of the bias RF. The bias RF power supply (132) and the source RF power supply (152) can be synchronized or desynchronized with each other through a tuner of the control unit.

[0075] The above control unit is connected to the first power supply unit (150) and the second power supply unit (130) to control their operation. The control unit includes a microcomputer and various interfaces, and can control the operation of the plasma processing device according to program and recipe information stored in external memory or internal memory.

[0076] When high-frequency power having a predetermined frequency is applied to the upper electrode (140), the electromagnetic field induced by the upper electrode (140) is applied to the plasma gas injected into the plasma chamber (110), thereby generating plasma (P). The bias power is applied to the lower electrode to attract plasma atoms or ions generated within the plasma chamber (110) toward the lower electrode.

[0077] FIG. 6 is a diagram showing the interior of a plasma chamber where steam is supplied by the gas supply unit of FIG. 5. FIG. 7 is a diagram showing the state in which the steam supplied by the gas supply unit of FIG. 5 is dissociated within the plasma chamber. FIG. 8 is a diagram showing the state in which the plasma gas and steam supplied by the gas supply unit of FIG. 5 are dissociated within the plasma chamber.

[0078] Referring to FIG. 6, the steam supply unit (174) can supply steam into the plasma chamber (110). The steam supply unit (174) can supply the steam into the plasma chamber (110) when the wafer is in the load lock chamber (300) or the vacuum transfer module (200). The steam supply unit (174) can supply steam into the plasma chamber (110) before plasma is generated within the plasma chamber (110).

[0079] Referring to FIG. 7, after the water vapor is supplied into the plasma chamber (110), plasma (P) can be generated inside the plasma chamber (110). Due to the dissociation action of the plasma, the water vapor supplied into the plasma chamber (110) is H + , H * , H2 + , O + , O2 + , O * , OH + , OH * It can dissociate into various ions and radicals.

[0080] Referring to FIG. 8, the steam supply unit (174) can supply steam at the same time that the plasma gas supply unit (172) supplies plasma gas. The steam supply unit (174) can supply steam into the plasma chamber (110) before or when plasma is generated within the plasma chamber (110).

[0081] Due to the dissociation action of the plasma, the plasma gas and water vapor supplied into the plasma chamber (110) can be dissociated into various ions and radicals.

[0082] As described above, the plasma chamber (110) can increase productivity by performing plasma treatment on wafers while maintaining a constant vacuum state using a load lock chamber (300). However, due to the constant vacuum maintenance of the plasma chamber (110), the amount of OH radicals generated is reduced due to the decrease in moisture within the plasma chamber (110), which may lower the bonding strength between the wafers.

[0083] In exemplary embodiments, the water vapor supply unit (174) can supply water vapor into the plasma chamber (110). Water vapor can be supplied into the plasma chamber (110) before or when plasma is generated within the plasma chamber (110). Thus, due to the dissociation action of the plasma, the water vapor can be dissociated, and the amount of OH radicals generated can be significantly increased compared to the conventional method. Accordingly, even if the plasma chamber (110) is maintained in a constant vacuum state, the moisture inside the plasma chamber (110) can be maintained above a certain level to increase and maintain the amount of OH radicals generated, thereby improving and maintaining the bonding strength between wafers.

[0084] Below, a method for bonding wafers using the wafer bonding system of Fig. 1 will be described.

[0085] FIG. 9 is a flowchart illustrating a wafer bonding method according to exemplary embodiments. FIG. 10 is a diagram illustrating the wafer bonding method of FIG. 9. FIG. 11 is a flowchart illustrating detailed steps of the plasma treatment step of FIG. 9. FIG. 12 and FIG. 13 are timing diagrams illustrating the plasma treatment step according to exemplary embodiments.

[0086] Referring to FIGS. 1 to 13, first, plasma treatment can be performed on at least one of the bonding surfaces of wafers bonded to each other (S10).

[0087] In exemplary embodiments, the wafer can be introduced into a load lock chamber (300) under atmospheric pressure (S100).

[0088] As illustrated in FIGS. 1 and 2, when the wafer is transported to the front of the load lock chamber (300) at atmospheric pressure by the first transfer robot (60) acting as a substrate transfer device, the first gate valve (312) can be opened. Subsequently, the wafer can be loaded onto a substrate plate (312) inside the load lock chamber (300) at atmospheric pressure by the first transfer robot (60). At this time, if a wafer that has already been plasma-treated is loaded on another substrate plate, the first transfer robot (60) can receive the wafer on the other substrate plate and remove it from the load lock chamber (300).

[0089] Next, the load lock chamber (300) can be switched to a vacuum state (S110). The first gate valve (312) is closed and the first vacuum pump (318) is operated so that the load lock chamber (300) is depressurized and switched to a vacuum state.

[0090] Afterwards, the wafer can be moved to a vacuum transfer module (200) connected to a load lock chamber (300) (S120), and steam can be supplied into a plasma chamber (110) (S130).

[0091] The second gate valve (212) is opened, and the transfer device (220) within the vacuum transfer module (200) can move the wafer loaded on the substrate plate (320) into the vacuum transfer module (20).

[0092] As illustrated in FIG. 12, before sequentially plasma-processing wafers (#1, #2, ..., #(n-1), #n) of one lot (Lot A, Lot B) into the plasma chamber (110), the water vapor supply unit (174) can supply water vapor into the plasma chamber (110). The water vapor supply unit (174) can supply the water vapor into the plasma chamber (110) before the wafers are loaded into the plasma chamber (110). After supplying the above water vapor into the plasma chamber (110), plasma treatment can be sequentially performed on the first wafer (#1(A)) of Lot A, the first wafer (#1(B)) of Lot B, the second wafer (#2(A)) of Lot A, the second wafer (#2(B)) of Lot B, ..., the nth wafer (#n(A)) of Lot A and the nth wafer (#n(B)) of Lot B. After plasma treatment of the wafers of Lot A and B is performed, the water vapor supply unit (174) can supply water vapor into the plasma chamber (110). The plasma-treated wafers of Lot A and Lot B can be bonded together in a subsequent bonding process.

[0093] For example, one lot may contain 25 wafers. However, it is not limited to this, and it will be understood that the steam may be supplied before processing various quantities of wafers, such as lot units or batch units.

[0094] Next, the wafer can be loaded into the plasma chamber (110) from the vacuum transfer module (200) (S140).

[0095] The third gate valve (112) is opened, and the transfer device (220) within the vacuum transfer module (200) can transfer the wafer loaded on the substrate plate (320) into the plasma chamber (110) of the substrate processing device (100).

[0096] Afterwards, the third gate valve (112) is closed, and plasma treatment can be performed on the wafer in the plasma chamber (110) (S150).

[0097] As illustrated in FIGS. 4 and 5, the plasma gas supply unit (172) introduces plasma gas into the plasma chamber (110) through the injection holes (162) of the shower head (160), and the pressure inside the plasma chamber (110) can be adjusted to a high vacuum pressure by the exhaust unit (116). Subsequently, plasma power is applied to the upper electrode (140) to form plasma (P) inside the plasma chamber (110), and bias power is applied to the lower electrode to perform a plasma treatment process.

[0098] As illustrated in FIG. 13, before and during the plasma treatment of wafers (#1, #2, ..., #(n-1), #n) of a lot (Lot A, Lot B) sequentially in the plasma chamber (110), the water vapor supply unit (174) can supply water vapor into the plasma chamber (110). For example, the water vapor supply unit (174) can supply the water vapor into the plasma chamber (110) whenever plasma treatment of all wafers is performed. The water vapor supply unit (174) can supply the water vapor at the same time that the plasma gas supply unit (172) supplies the plasma gas. Alternatively, the water vapor supply unit (174) can supply the water vapor into the plasma chamber (110) whenever plasma treatment of multiple wafers (e.g., 2, 4, 6, etc.) is performed.

[0099] The steam supply unit (174) can supply the steam into the plasma chamber (110) when the wafer is in the load lock chamber (300). Additionally, the steam supply unit (174) can supply the steam into the plasma chamber (110) when performing plasma treatment on a specific wafer (e.g., wafer #2). The steam supply unit (174) can supply the steam at the same time that the plasma gas supply unit (172) supplies the plasma gas.

[0100] Next, the wafer can be unloaded from the plasma chamber (110) to the vacuum transfer module (200) (S160), the wafer can be moved from the vacuum transfer module (220) to the load lock chamber (300) in a vacuum pressure state (S170), the load lock chamber (300) can be switched to an atmospheric pressure state (S180), and the wafer can be removed from the load lock chamber (300) in an atmospheric pressure state (S190).

[0101] When the surface treatment of the wafer is completed, the second and third gate valves (212, 112) are opened, and the transfer device (220) can take the wafer out of the plasma chamber (110) and transfer it to the substrate plate (320) of the load lock chamber (300). Subsequently, after the second and third gate valves (212, 112) are closed, nitrogen or dry air can be supplied into the load lock chamber (300) to form the internal pressure to atmospheric pressure. Accordingly, the indoor atmosphere of the load lock chamber (300) can be switched from a reduced pressure state to an atmospheric pressure state. Afterward, the first gate valve (312) is opened, and the transfer robot (60) can take the plasma-treated wafer out of the substrate plate (320) of the load lock chamber (300) and transfer it to a cleaning device (80) where the next treatment is performed.

[0102] Next, the plasma-treated wafer surface can be cleaned (S20), and the cleaned wafers can be bonded together (S30). Afterwards, the bonded wafers can be annealed (S40).

[0103] In exemplary embodiments, the surface of the wafer can be cleaned using the DI water, including a nozzle for spraying DI water and a support member capable of supporting and rotating the wafer. The DI water not only cleans the surface of the wafer but also facilitates the bonding of the wafer by allowing -OH groups and water molecules to bond well to the surface of the wafer.

[0104] Next, the cleaned wafers (W1, W2) are loaded into a wafer bonding device (90), and then the wafers can be adsorbed and fixed to an upper stage (410) and a lower stage (400), respectively. The first wafer (W1) can be vacuum adsorbed by pressure relief holes (412) formed in the upper stage (410). The second wafer (W2) can be vacuum adsorbed by pressure relief holes (402) formed in the lower stage (400).

[0105] Next, the push rod (430) descends to press the center portion of the first wafer (W1) so that the first wafer (W1) can be bent downward in a convex manner. At this time, only the peripheral portion of the first wafer (W1) can be vacuum-adsorbed by the pressure relief holes (412) formed in the upper stage (410).

[0106] With the first wafer (W1) deformed in a convex shape downward, the upper stage (410) can be lowered to bring the first wafer (W1) into contact with the second wafer (W2). At this time, the center portion of the first wafer (W1) first comes into contact with the second wafer (W2) and then gradually comes into contact with it outward. Subsequently, by removing the vacuum pressure in the pressure relief holes (412) of the upper stage (410), the first wafer (W1) and the second wafer (W2) can be bonded together.

[0107] Next, the bonded wafers can be heat-treated by an annealing device.

[0108] The aforementioned wafer bonding system and wafer bonding method may be applied to a semiconductor package or image sensor including a logic device or a memory device. The semiconductor package may include volatile memory devices such as SRAM devices, DRAM devices, high bandwidth memory (HBM) devices, etc., and non-volatile memory devices such as flash memory devices, PRAM devices, MRAM devices, RRAM devices, etc. The image sensor may include a CMOS image sensor.

[0109] Although the present invention has been described above with reference to embodiments thereof, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims. Explanation of the symbols

[0110] 10: Wafer bonding system 20: Index module 22: Processor Module 30: Cassette Stage 40: Indexer Robot 50: Alignment device 52: Position adjustment mechanism 60: 1st transfer robot 62: 2nd transfer robot 70: Plasma treatment device 80: Cleaning device 90: Wafer bonding device 100: Substrate processing device 110: Plasma chamber

Claims

Claim 1 A plasma processing device comprising: a load lock chamber switchable between an atmospheric pressure state and a vacuum pressure state; and a substrate processing device for performing substrate transfer with said load lock chamber and performing plasma treatment on the surface of said substrate in a plasma chamber in a vacuum pressure state, wherein the substrate processing device comprises: a substrate support member disposed within the plasma chamber and for supporting a substrate from said load lock chamber; a plasma gas supply member for supplying plasma gas into said plasma chamber; a steam supply member for supplying steam into said plasma chamber; and a plasma generator for generating plasma within said plasma chamber, wherein the steam supply member supplies said steam into said plasma chamber prior to sequential plasma treatment of a plurality of substrates and while said substrate is in said load lock chamber. Claim 2 delete Claim 3 In claim 1, the steam supply unit supplies the steam into the plasma chamber before the plasma is generated within the plasma chamber. Claim 4 A plasma processing device according to claim 1, wherein the steam supply unit supplies the steam at the same time as the plasma gas supply unit supplies the plasma gas. Claim 5 In claim 1, the steam supply unit comprises: a steam source for supplying the steam; a steam supply line connected to the steam source for supplying the steam into the plasma chamber; and a flow controller installed in the steam supply line for controlling the supply flow rate of the steam, forming a plasma processing apparatus. Claim 6 A plasma treatment apparatus according to claim 5, wherein the steam supply unit further comprises a heater jacket that surrounds at least a portion of the steam supply line and prevents the steam within the steam supply line from condensing. Claim 7 In claim 5, the steam supply unit further comprises a temperature sensor for detecting the temperature of the steam within the steam source; and a pressure sensor for detecting the pressure of the steam within the steam source, in a plasma processing apparatus. Claim 8 A plasma processing apparatus according to claim 1, further comprising a vacuum transfer module for transferring the substrate between the load lock chamber and the substrate processing apparatus under vacuum pressure. Claim 9 delete Claim 10 delete Claim 11 A substrate transfer device for transferring a substrate in an atmospheric pressure state; a substrate processing device for performing plasma treatment on the surface of the substrate in a plasma chamber in a vacuum pressure state; a load lock chamber capable of transferring the substrate between the substrate transfer device and the substrate processing device and switching between an atmospheric pressure state and a vacuum pressure state; a vacuum transfer module for transferring the substrate between the load lock chamber and the plasma chamber in a vacuum pressure state; and a steam supply unit for supplying steam into the plasma chamber, wherein the steam supply unit supplies the steam into the plasma chamber prior to sequential plasma treatment of a plurality of substrates and while the substrate is in the load lock chamber or the vacuum transfer module. Claim 12 In claim 11, when the load lock chamber is in a vacuum pressure state, the vacuum transfer module is depressurized to a vacuum pressure state and communicates with the load lock chamber, forming a plasma processing device. Claim 13 delete Claim 14 delete Claim 15 delete Claim 16 delete Claim 17 delete Claim 18 delete Claim 19 delete Claim 20 An index module for loading and unloading wafers; a substrate transfer device for transferring the wafers from the index module in an atmospheric pressure state; a substrate processing device for performing plasma treatment on the wafer surface in a plasma chamber in a vacuum pressure state; a load lock chamber capable of transferring the wafer between the substrate transfer device and the substrate processing device and switching between an atmospheric pressure state and a vacuum pressure state; a vacuum transfer module for transferring the wafer between the load lock chamber and the plasma chamber in a vacuum pressure state; a cleaning device for cleaning the wafer surface plasma-treated by the substrate processing device; and a wafer bonding device for bonding the cleaned wafers together, wherein the substrate processing device includes a steam supply unit for supplying steam into the plasma chamber, and the steam supply unit supplies the steam into the plasma chamber prior to sequential plasma treatment of a plurality of substrates and while the substrate is in the load lock chamber or the vacuum transfer module.

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