Computer program, substrate bonding system, and substrate bonding method

Abstract

To provide a computer program, a substrate bonding system, and a substrate bonding method that can determine the type of a foreign matter on a substrate held in a chuck.SOLUTION: A computer program causes a computer to execute processing of acquiring displacement data at multiple locations on the surface of a substrate held by a chuck, identifying the distribution of surface displacement on the basis of the acquired displacement data, and determining the type of foreign matter on the basis of the identified distribution.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a computer program, a substrate bonding system, and a substrate bonding method. [Background technology]

[0002] Patent Document 1 discloses a substrate processing apparatus comprising a chuck for adsorbing and holding a substrate, an observation unit for observing multiple locations on a second surface of the substrate held by the chuck, opposite to a first surface in contact with the chuck, and an analysis unit for analyzing the observation results of the multiple locations. The analysis unit identifies the location of a singularity on the chuck if such singularity exists on the second surface with respect to the height of the chuck from the surface that adsorbs and holds the substrate. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-141034 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] This disclosure provides a computer program capable of determining the type of foreign matter on a substrate held in a chuck, a substrate bonding system, and a substrate bonding method. [Means for solving the problem]

[0005] A computer program according to one aspect of the present disclosure causes the computer to perform the following processes: acquire displacement data from multiple locations on the surface of a substrate held in a chuck; identify the distribution of displacement on the surface based on the acquired displacement data; and determine the type of foreign object based on the identified distribution. [Effects of the Invention]

[0006] According to this disclosure, the type of foreign matter on the substrate held in the chuck can be determined. [Brief explanation of the drawing]

[0007] [Figure 1] This is a plan view showing a joining system according to one embodiment. [Figure 2] A side view showing a joining system according to one embodiment. [Figure 3] This is a side view showing the state of the first substrate and the second substrate before bonding according to one embodiment. [Figure 4] This is a plan view showing a joining device according to one embodiment. [Figure 5] This is a side view showing a joining device according to one embodiment. [Figure 6] This is a cross-sectional view showing an upper chuck and a lower chuck according to one embodiment, and is a cross-sectional view showing the state immediately before joining the upper wafer and the lower wafer. [Figure 7] This is a cross-sectional view showing the state during the bonding process between the upper and lower wafers according to one embodiment. [Figure 8] This flowchart shows some of the processes performed by a joining system according to one embodiment. [Figure 9] This figure shows an example of a method for observing the bonding surface of the lower wafer according to one embodiment. [Figure 10] This figure shows an example of displacement data according to one embodiment. [Figure 11] This figure shows an example of a processing procedure for an information processing device according to one embodiment. [Figure 12] This figure shows an example of peak detection according to one embodiment. [Figure 13] This figure shows an example of trend removal using one embodiment. [Figure 14] This figure shows an example of normalization according to one embodiment. [Figure 15] This figure shows an example of curve fitting according to one embodiment. [Figure 16] This figure shows an example of calculating the coefficient of determination using one embodiment. [Figure 17] This figure shows an example of foreign matter between the lower wafer and the lower chuck according to one embodiment. [Figure 18] It is a figure showing an example of an abnormality other than foreign matter between the lower wafer and the lower chuck according to an embodiment.

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components may be denoted by the same or corresponding reference numerals, and the description thereof may be omitted. In the following description, the X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to each other, the X-axis direction and the Y-axis direction are horizontal directions, and the Z-axis direction is a vertical direction. The rotation direction about the vertical axis is also referred to as the θ direction. In this specification, "downward" means vertically downward, and "upward" means vertically upward.

[0009] FIG. 1 is a plan view showing a bonding system according to an embodiment. FIG. 2 is a side view showing a bonding system according to an embodiment. FIG. 3 is a side view showing a state before bonding of a first substrate and a second substrate according to an embodiment. The bonding system 1 shown in FIG. 1 forms a polymerized substrate T (see FIG. 7B) by bonding a first substrate W1 and a second substrate W2.

[0010] The first substrate W1 is a substrate on which a plurality of electronic circuits are formed on a semiconductor substrate such as a silicon wafer or a compound semiconductor wafer. The second substrate W2 is, for example, a bare wafer on which no electronic circuit is formed. The first substrate W1 and the second substrate W2 have substantially the same diameter. Note that an electronic circuit may be formed on the second substrate W2.

[0011] Hereinafter, the first substrate W1 may be described as the "upper wafer W1", the second substrate W2 as the "lower wafer W2", and the polymerized substrate T as the "polymerized wafer T". Further, hereinafter, as shown in FIG. 3, among the plate surfaces of the upper wafer W1, the plate surface on the side bonded to the lower wafer W2 is described as the "bonding surface W1j", and the plate surface on the side opposite to the bonding surface W1j is described as the "non-bonding surface W1n". Among the plate surfaces of the lower wafer W2, the plate surface on the side bonded to the upper wafer W1 is described as the "bonding surface W2j", and the plate surface on the side opposite to the bonding surface W2j is described as the "non-bonding surface W2n".

[0012] As shown in Figure 1, the joining system 1 comprises an input / output station 2 and a processing station 3. The input / output station 2 and the processing station 3 are arranged in the order of input / output station 2 and processing station 3 along the positive X-axis. The input / output station 2 and the processing station 3 are also integrally connected.

[0013] The loading / unloading station 2 comprises a mounting table 10 and a transport area 20. The mounting table 10 comprises a plurality of mounting plates 11. Each mounting plate 11 is fitted with cassettes C1, C2, and C3, which accommodate multiple substrates (for example, 25) in a horizontal position. For example, cassette C1 is a cassette for accommodating the upper wafer W1, cassette C2 is a cassette for accommodating the lower wafer W2, and cassette C3 is a cassette for accommodating the polymerized wafer T.

[0014] The transport area 20 is positioned adjacent to the positive X-axis side of the mounting table 10. The transport area 20 is provided with a transport path 21 extending in the Y-axis direction and a transport device 22 that can move along this transport path 21. The transport device 22 can move not only in the Y-axis direction but also in the X-axis direction and can rotate around the Z-axis, and transports the upper wafer W1, lower wafer W2, and polymerized wafer T between the cassettes C1 to C3 placed on the mounting plate 11 and the third processing block G3 of the processing station 3, which will be described later.

[0015] The number of cassettes C1 to C3 placed on the mounting plate 11 is not limited to those shown in the illustration. In addition, other cassettes such as those for collecting faulty circuit boards may be placed on the mounting plate 11 besides cassettes C1, C2, and C3.

[0016] Processing station 3 is equipped with multiple processing blocks, such as three processing blocks G1, G2, and G3, each containing various devices. For example, the first processing block G1 is located on the front side of processing station 3 (negative Y-axis direction in Figure 1), and the second processing block G2 is located on the rear side of processing station 3 (positive Y-axis direction in Figure 1). In addition, the third processing block G3 is located on the loading / unloading station 2 side of processing station 3 (negative X-axis direction in Figure 1).

[0017] The first processing block G1 is equipped with a surface modification apparatus 30 that modifies the bonding surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2. The surface modification apparatus 30 modifies the bonding surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2 by breaking the SiO2 bonds in the bonding surfaces W1j and W2j to create single-bonded SiO, thereby making them more easily hydrophilized afterward.

[0018] In the surface modification apparatus 30, for example, under a reduced pressure atmosphere, oxygen gas or nitrogen gas, which is the processing gas, is excited and plasma-generated, and then ionized. These oxygen ions or nitrogen ions are then irradiated onto the bonding surfaces W1j and W2j of the upper wafer W1 and the lower wafer W2, thereby plasma-treated and modified the bonding surfaces W1j and W2j.

[0019] The second processing block G2 is equipped with a surface hydrophilization device 40 and a bonding device 41. The surface hydrophilization device 40 hydrophilizes the bonding surfaces W1j and W2j of the upper wafer W1 and lower wafer W2 using, for example, pure water, and also cleans the bonding surfaces W1j and W2j. The surface hydrophilization device 40 supplies pure water onto the upper wafer W1 or lower wafer W2 while rotating the upper wafer W1 or lower wafer W2, for example, which is held in a spin chuck. As a result, the pure water supplied onto the upper wafer W1 or lower wafer W2 diffuses over the bonding surfaces W1j and W2j of the upper wafer W1 or lower wafer W2, and the bonding surfaces W1j and W2j are made hydrophilic.

[0020] The bonding apparatus 41 bonds the hydrophilized upper wafer W1 and the lower wafer W2 by intermolecular forces. The configuration of the bonding apparatus 41 will be described later.

[0021] As shown in Figure 2, the third processing block G3 is equipped with two stages of transition (TRS) devices 50 and 51 for the upper wafer W1, the lower wafer W2, and the polymerized wafer T, starting from the bottom.

[0022] Furthermore, as shown in Figure 1, a transport area 60 is formed in the region enclosed by the first processing block G1, the second processing block G2, and the third processing block G3. A transport device 61 is arranged in the transport area 60. The transport device 61 has a transport arm that is movable, for example, in the vertical direction, horizontal direction, and around the vertical axis. The transport device 61 moves within the transport area 60 and transports the upper wafer W1, the lower wafer W2, and the polymerized wafer T to predetermined devices in the first processing block G1, the second processing block G2, and the third processing block G3 adjacent to the transport area 60.

[0023] As shown in Figure 1, the bonding system 1 includes a control device 70 and an information processing device 80. The control device 70 controls the operation of the bonding system 1. The control device 70 is, for example, a computer and has a CPU (Central Processing Unit) 71, a storage medium 72 such as memory, an input interface 73, and an output interface 74. The control device 70 performs various controls by causing the CPU 71 to execute a program stored in the storage medium 72. The control device 70 also receives signals from the outside through the input interface 73 and transmits signals to the outside through the output interface 74. The control device 70 is an example of an analysis unit.

[0024] The program for the control device 70 is stored on an information storage medium and installed from that medium. Examples of information storage media include hard disks (HDs), flexible disks (FDs), compact disks (CDs), magnetic optical disks (MOs), and memory cards. Alternatively, the program may be downloaded from a server via the internet and then installed. Details of the information processing device 80 will be described later.

[0025] Figure 4 is a plan view showing a joining device according to one embodiment. Figure 5 is a side view showing a joining device according to one embodiment.

[0026] As shown in Figure 4, the bonding apparatus 41 has a processing container 100 whose interior can be sealed. On the side of the processing container 100 facing the transport area 60, an inlet / outlet 101 for the upper wafer W1, the lower wafer W2, and the polymerized wafer T is formed, and an opening / closing shutter 102 is provided at the inlet / outlet 101. The processing container 100 is an example of a processing chamber.

[0027] The processing container 100 is provided with an upper chuck 140 that holds the upper surface (non-bonding surface W1n) of the upper wafer W1 from above by suction, and a lower chuck 141 on which the lower wafer W2 is placed and holds the lower surface (non-bonding surface W2n) of the lower wafer W2 from below by suction. The lower chuck 141 is provided below the upper chuck 140 and is configured to be positioned opposite the upper chuck 140. The upper chuck 140 and the lower chuck 141 are positioned spaced apart in the vertical direction.

[0028] As shown in Figure 5, the upper chuck 140 is held by an upper chuck holder 150 located above the upper chuck 140. The upper chuck holder 150 is located on the ceiling surface of the processing container 100. The upper chuck 140 is fixed to the processing container 100 via the upper chuck holder 150.

[0029] The upper chuck holding section 150 is provided with an upper imaging section 151A for imaging the upper surface (bonding surface W2j) of the lower wafer W2 held by the lower chuck 141. For example, a CCD camera is used for the upper imaging section 151A. The upper chuck holding section 150 is further provided with an upper displacement meter 151B for measuring the displacement of the upper surface (bonding surface W2j) of the lower wafer W2 held by the lower chuck 141. For example, an LED displacement meter is used for the upper displacement meter 151B. The upper imaging section 151A is an example of an imaging device, and the upper displacement meter 151B is an example of a displacement meter.

[0030] The lower chuck 141 is supported by a first lower chuck moving part 160 located below the lower chuck 141. The first lower chuck moving part 160 moves the lower chuck 141 horizontally (in the X-axis direction), as will be described later. The first lower chuck moving part 160 is also configured to allow the lower chuck 141 to move vertically and rotate around a vertical axis.

[0031] The first lower chuck movement unit 160 is provided with a lower imaging unit 161A that images the lower surface (bonding surface W1j) of the upper wafer W1 held by the upper chuck 140 (see Figure 5). For example, a CCD camera is used for the lower imaging unit 161A. The first lower chuck movement unit 160 is further provided with a lower displacement meter 161B that measures the displacement of the lower surface (bonding surface W1j) of the upper wafer W1 held by the upper chuck 140. For example, an LED displacement meter is used for the lower displacement meter 161B.

[0032] The first lower chuck moving part 160 is provided on the lower side of the first lower chuck moving part 160 and is attached to a pair of rails 162, 162 that extend horizontally (in the X-axis direction). The first lower chuck moving part 160 is configured to be movable along the rails 162.

[0033] A pair of rails 162, 162 are arranged on the second lower chuck moving section 163. The second lower chuck moving section 163 is provided on the lower side of the second lower chuck moving section 163 and is attached to a pair of rails 164, 164 that extend horizontally (in the Y-axis direction). The second lower chuck moving section 163 is configured to move horizontally (in the Y-axis direction) along the rails 164. The pair of rails 164, 164 are arranged on a mounting base 165 provided on the bottom surface of the processing container 100.

[0034] The alignment unit 166 is formed by the first lower chuck moving unit 160 and the second lower chuck moving unit 163, etc. The alignment unit 166 performs horizontal alignment between the upper wafer W1 held by the upper chuck 140 and the lower wafer W2 held by the lower chuck 141 by moving the lower chuck 141 in the X-axis direction, Y-axis direction, and θ-axis direction. The alignment unit 166 also performs vertical alignment between the upper wafer W1 held by the upper chuck 140 and the lower wafer W2 held by the lower chuck 141 by moving the lower chuck 141 in the Z-axis direction.

[0035] In this embodiment, the alignment unit 166 performs horizontal alignment of the upper wafer W1 and the lower wafer W2 by moving the lower chuck 141 in the X-axis direction, Y-axis direction, and θ-axis direction, but this disclosure is not limited thereto. The alignment unit 166 only needs to be able to move the upper chuck 140 and the lower chuck 141 relatively in the X-axis direction, Y-axis direction, and θ-axis direction. For example, the alignment unit 166 may perform horizontal alignment of the upper wafer W1 and the lower wafer W2 by moving the lower chuck 141 in the X-axis direction and Y-axis direction, and moving the upper chuck 140 in the θ-axis direction.

[0036] Furthermore, while the alignment unit 166 of this embodiment performs vertical alignment of the upper wafer W1 and the lower wafer W2 by moving the lower chuck 141 in the Z-axis direction, the disclosure is not limited thereto. The alignment unit 166 only needs to be able to move the upper chuck 140 and the lower chuck 141 relative to each other in the Z-axis direction. For example, the alignment unit 166 may perform vertical alignment of the upper wafer W1 and the lower wafer W2 by moving the upper chuck 140 in the Z-axis direction.

[0037] Figure 6 is a cross-sectional view showing the upper and lower chucks according to one embodiment, showing the state immediately before bonding the upper and lower wafers. Figure 7A is a cross-sectional view showing the state during bonding of the upper and lower wafers according to one embodiment. Figure 7B is a cross-sectional view showing the state after bonding of the upper and lower wafers is completed according to one embodiment. In Figures 6, 7A, and 7B, the arrows shown by solid lines indicate the direction of air suction by the vacuum pump.

[0038] The upper chuck 140 and the lower chuck 141 are, for example, vacuum chucks. The upper chuck 140 has an adsorption surface 140a for adsorbing the upper wafer W1 on the surface (bottom surface) facing the lower chuck 141. On the other hand, the lower chuck 141 has an adsorption surface 141a for adsorbing the lower wafer W2 on the surface (top surface) facing the upper chuck 140.

[0039] The upper chuck 140 has a chuck base 170. The chuck base 170 has a diameter equal to or larger than that of the upper wafer W1. The chuck base 170 is supported by a support member 180. The support member 180 is provided so as to cover at least the chuck base 170 in a plan view and is fixed to the chuck base 170, for example, by screw fastening. The support member 180 is supported by a plurality of support columns 181 (see Figure 5) provided on the ceiling surface of the processing container 100. The support member 180 and the plurality of support columns 181 constitute the upper chuck holding portion 150.

[0040] The support member 180 and the chuck base 170 have through-holes 176 that penetrate vertically through them. The position of the through-holes 176 corresponds to the center of the upper wafer W1 that is held by the upper chuck 140. The pressing pins 191 of the striker 190 are inserted through these through-holes 176.

[0041] The striker 190 is positioned on the upper surface of the support member 180 and comprises a pressing pin 191, an actuator 192, and a linear motion mechanism 193. The pressing pin 191 is a cylindrical member extending along the vertical direction and is supported by the actuator 192.

[0042] The actuator unit 192 generates a constant pressure in a specific direction (here, vertically downward) using air supplied, for example, from an electro-pneumatic regulator (not shown). The actuator unit 192 can contact the center of the upper wafer W1 using the air supplied from the electro-pneumatic regulator and control the pressing load applied to the center of the upper wafer W1. Furthermore, the tip of the actuator unit 192 is able to move up and down vertically by passing through the through hole 176 using air from the electro-pneumatic regulator.

[0043] The actuator unit 192 is supported by the linear motion mechanism 193. The linear motion mechanism 193 moves the actuator unit 192 in the vertical direction, for example, by a drive unit that incorporates a motor.

[0044] The striker 190 is configured as described above, with the linear motion mechanism 193 controlling the movement of the actuator unit 192, and the actuator unit 192 controlling the pressing load on the upper wafer W1 by the pressing pin 191.

[0045] The striker 190 presses the upper wafer W1, which is held by the upper chuck 140, against the lower wafer W2, which is held by the lower chuck 141. Specifically, the striker 190 deforms the upper wafer W1, which is held by the upper chuck 140, thereby pressing it against the lower wafer W2.

[0046] The lower surface of the chuck base 170 is provided with a plurality of pins 171 that contact the non-bonding surface W1n of the upper wafer W1. The upper chuck 140 is composed of the chuck base 170, the plurality of pins 171, etc. The suction surface 140a of the upper chuck 140 that adsorbs and holds the upper wafer W1 is divided into a plurality of regions in the radial direction, and the generation and release of suction force occurs for each divided region.

[0047] The lower chuck 141 may be configured in the same way as the upper chuck 140. The lower chuck 141 has a plurality of pins that contact the non-bonding surface W2n of the lower wafer W2. The suction surface 141a of the lower chuck 141 that adsorbs and holds the lower wafer W2 is divided into a plurality of regions in the radial direction, and the generation and release of suction force occurs for each divided region.

[0048] Figure 8 is a flowchart showing some of the processes performed by a joining system according to one embodiment. The various processes shown in Figure 8 are performed under the control of the control device 70.

[0049] First, cassette C1 containing multiple upper wafers W1, cassette C2 containing multiple lower wafers W2, and an empty cassette C3 are placed on a designated mounting plate 11 at the loading / unloading station 2. Then, the upper wafers W1 are removed from cassette C1 by the transport device 22 and transported to the transition device 50 in the third processing block G3 of the processing station 3.

[0050] Next, the upper wafer W1 is transported by the transport device 61 to the surface modification apparatus 30 of the first processing block G1. In the surface modification apparatus 30, under a predetermined reduced pressure atmosphere, oxygen gas, which is the processing gas, is excited, plasma-generated, and ionized. These oxygen ions are irradiated onto the bonding surface W1j of the upper wafer W1, and the bonding surface W1j is plasma-treated. As a result, the bonding surface W1j of the upper wafer W1 is modified (step S101).

[0051] Next, the upper wafer W1 is transported by the transport device 61 to the surface hydrophilization device 40 in the second processing block G2. In the surface hydrophilization device 40, the upper wafer W1, which is held in a spin chuck, is rotated while pure water is supplied onto the upper wafer W1. The supplied pure water diffuses over the bonding surface W1j of the upper wafer W1, and hydroxyl groups (silanol groups) adhere to the bonding surface W1j of the upper wafer W1 that has been modified in the surface modification device 30, making the bonding surface W1j hydrophilic (step S102). In addition, the bonding surface W1j of the upper wafer W1 is cleaned with the pure water used to hydrophilize the bonding surface W1j.

[0052] Next, the upper wafer W1 is transported by the transport device 61 to the bonding device 41 of the second processing block G2 (step S103). At this time, the upper wafer W1 is transported with its front and back surfaces reversed. That is, the bonding surface W1j of the upper wafer W1 is oriented downwards.

[0053] Subsequently, within the bonding apparatus 41, the transfer arm of the transfer device 61 moves below the upper chuck 140. The upper wafer W1 is then transferred from the transfer arm to the upper chuck 140. The upper wafer W1 is held by suction on the upper chuck 140 with its non-bonding surface W1n in contact with the upper chuck 140 (step S104).

[0054] While the processing described in steps S101 to S104 is being performed on the upper wafer W1, the processing of the lower wafer W2 is carried out. First, the lower wafer W2 is removed from the cassette C2 by the transport device 22 and transported to the transition device 50 of the processing station 3.

[0055] Next, the lower wafer W2 is transported to the surface modification apparatus 30 by the transport device 61, and the bonding surface W2j of the lower wafer W2 is modified (step S105). The modification of the bonding surface W2j of the lower wafer W2 in step S105 is the same as in step S101 described above.

[0056] Subsequently, the lower wafer W2 is transported by the transport device 61 to the surface hydrophilization device 40, where the bonding surface W2j of the lower wafer W2 is hydrophilized (step S106). The bonding surface W2j is also cleaned with pure water used for hydrophilization. Note that the hydrophilization of the bonding surface W2j of the lower wafer W2 in step S106 is the same as the hydrophilization of the bonding surface W1j of the upper wafer W1 in step S102.

[0057] Subsequently, the lower wafer W2 is transported to the bonding apparatus 41 by the transport device 61 (step S107).

[0058] Subsequently, within the bonding apparatus 41, the transfer arm of the transfer device 61 moves above the lower chuck 141. The lower wafer W2 is then transferred from the transfer arm to the lower chuck 141. The lower wafer W2 is held by suction to the lower chuck 141 with its non-bonding surface W2n in contact with the lower chuck 141 (step S108).

[0059] Next, the upper wafer W1 held by the upper chuck 140 and the lower wafer W2 held by the lower chuck 141 are adjusted in the horizontal direction (step S109). For this alignment, alignment marks W1a, W1b, and W1c that are pre-formed on the bonding surface W1j of the upper wafer W1 and alignment marks W2a, W2b, and W2c that are pre-formed on the bonding surface W2j of the lower wafer W2 are used.

[0060] Next, the vertical position of the upper wafer W1 held by the upper chuck 140 and the lower wafer W2 held by the lower chuck 141 is adjusted (step S110). Specifically, the alignment unit 166 moves the lower chuck 141 vertically upward, bringing the lower wafer W2 closer to the upper wafer W1. As a result, as shown in Figure 6, the distance WS1 between the bonding surface W2j of the lower wafer W2 and the bonding surface W1j of the upper wafer W1 is adjusted to a predetermined distance, for example, 50 μm to 200 μm. For example, the distance WS1 may be measured by the upper displacement meter 151B and the lower displacement meter 161B.

[0061] Next, after releasing the suction hold of the central part of the upper wafer W1 by the upper chuck 140 (step S111), the center of the upper wafer W1 is pushed down by lowering the pressing pin 191 of the striker 190, as shown in Figure 7A (step S112). When the center of the upper wafer W1 comes into contact with the center of the lower wafer W2, and the centers of the upper wafer W1 and the lower wafer W2 are pressed with a predetermined force, bonding begins between the pressed centers of the upper wafer W1 and the lower wafer W2. Subsequently, a bonding wave is generated that gradually bonds the upper wafer W1 and the lower wafer W2 from the center toward the outer edge.

[0062] Here, since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 are modified in steps S101 and S105, van der Waals forces (intermolecular forces) are first generated between the bonding surfaces W1j and W2j, and the bonding surfaces W1j and W2j are joined together. Furthermore, since the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 are hydrophilized in steps S102 and S106, the hydrophilic groups between the bonding surfaces W1j and W2j form hydrogen bonds, and the bonding surfaces W1j and W2j are firmly joined together.

[0063] Subsequently, with the center of the upper wafer W1 and the center of the lower wafer W2 pressed by the pressing pin 191, the overall suction holding of the upper wafer W1 by the upper chuck 140 is released (step S113). As a result, as shown in Figure 7B, the bonding surface W1j of the upper wafer W1 and the bonding surface W2j of the lower wafer W2 come into full contact, and the upper wafer W1 and the lower wafer W2 are bonded together. After that, the pressing pin 191 is raised to the upper chuck 140, and the suction holding of the lower wafer W2 by the lower chuck 141 is released.

[0064] Subsequently, the polymerized wafer T is transported by the transport device 61 to the transition device 51 of the third processing block G3, and then transported to the cassette C3 by the transport device 22 of the loading / unloading station 2. In this way, the series of bonding processes is completed.

[0065] During the process illustrated in Figure 8, for example, after the lower wafer W2 is held by the lower chuck 141 (step S108) and before the horizontal position adjustment of the upper wafer W1 and the lower wafer W2 (step S109), a foreign matter inspection is performed. As shown in Figure 6, during the process in which the upper wafer W1 and the lower wafer W2 come into close proximity and are joined, for example, suppose that foreign matter adheres to the non-joining surface W2n when the lower wafer W2 is held by the lower chuck 141. In this case, the lower wafer W2 is distorted and a bulge occurs in the lower wafer W2. As a result, a void is created between the lower wafer W2 and the upper wafer W1. The following describes a method for determining the type of foreign matter.

[0066] The information processing device 80 illustrated in Figure 1 performs a process to determine the type of foreign object. The information processing device 80 comprises a control unit 81 that controls the entire device, an interface unit 82, a peak detection unit 83, a preprocessing unit 84, a distribution identification unit 85, a recording medium reading unit 86, a determination unit 87, a memory 88, and a storage unit 89. The storage unit 89 stores a computer program 90.

[0067] The control unit 81 can be composed of a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), a GPU (Graphics Processing Unit), etc. The control unit 81 can execute the processes defined in the computer program 90. In other words, the processing performed by the control unit 81 is also the processing performed by the computer program 90.

[0068] The peak detection unit 83, preprocessing unit 84, distribution identification unit 85, and determination unit 87 may be configured as hardware, implemented as software (computer program 90), or configured as both hardware and software. The information processing device 80 may be configured as multiple devices.

[0069] The memory 88 can be composed of semiconductor memory such as SRAM (Static Random Access Memory), DRAM (Dynamic Random Access Memory), or flash memory. The computer program 90 can be loaded into the memory 88, and the control unit 81 can execute the computer program 90.

[0070] The storage unit 89 can be configured, for example, as a hard disk or semiconductor memory, and can store the necessary information (for example, data in progress or processing results from the information processing device 80).

[0071] The recording medium reading unit 86 can be configured, for example, as an optical disc drive. The recording medium reading unit 86 can read a computer program 90 (program product) recorded on a recording medium 91 (for example, an optically readable disc storage medium such as a CD-ROM) and store it in the storage unit 89. The computer program 90 is loaded into memory 88 and executed by the control unit 81. The computer program 90 may also be downloaded from an external device and stored in the storage unit 89.

[0072] The interface unit 82 functions as an acquisition unit and acquires displacement data from multiple locations on the surface (e.g., bonding surface W2j) of a substrate (e.g., lower wafer W2) held by a chuck (e.g., lower chuck 141).

[0073] Figure 9 shows an example of a method for observing the bonding surface W2j of the lower wafer W2 according to one embodiment. As shown in Figure 9, the upper displacement meter 151B measures the Z-axis displacement (height) of the bonding surface W2j of the lower wafer W2 while scanning the entire upper surface (bonding surface W2j) of the lower wafer W2. Specifically, the scanning includes each line L of the lower wafer W2 and the vicinity of the edges of the lower wafer W2. The interface unit 82 acquires displacement data from the upper displacement meter 151B.

[0074] Figure 10 shows an example of displacement data according to one embodiment. In the figure, the vertical axis shows the displacement (height) of the upper surface of the lower wafer W2, and the horizontal axis shows the index (position), which is the displacement measurement point. Figure 10 shows, for example, the displacement data for one line L of wafer W2. Figure 10A shows the case where foreign matter is attached to the lower surface (non-bonding surface W2n) of the lower wafer W2, and Figure 10B shows the case where the tilt of the lower chuck 141 (different from the foreign matter on the lower surface of the lower wafer W2) is tilted.

[0075] As shown in Figures 10A and 10B, in both cases, the distribution of displacement data shows distortion over a wide area of ​​the upper surface of the lower wafer W2, indicating that a bulge has occurred in the lower wafer W2. However, as shown in Figures 10A and 10B, distortion and bulging on the upper surface of the lower wafer W2 alone do not allow for determination of whether the foreign matter is present on the lower surface (non-bonding surface W2n) of the lower wafer W2, or whether it is another abnormality other than the foreign matter. As will be explained below, the information processing device 80 according to this embodiment can determine the type of foreign matter.

[0076] Figure 11 shows an example of the processing procedure of an information processing device 80 according to one embodiment. For convenience, the main processing unit will be described as the control unit 81. The control unit 81 acquires displacement data of the upper surface (surface) of the lower wafer W2 (S121) and formats the acquired displacement data (S122). Formatting the displacement data is a process that excludes data other than the upper surface of the lower wafer W2 from the displacement data. The control unit 81 performs peak detection on the displacement data (S123).

[0077] Figure 12 shows an example of peak detection according to one embodiment. The peak detection unit 83 identifies the maximum value of the displacement data for each line L of the lower wafer W2 and detects the peak. As a result, the peak detection unit 83 performs peak detection for all measurement points of the lower wafer W2. Peak detection detects the point with the maximum displacement among the measurement points for one line L as the peak. In other words, if there are multiple maximum values, the maximum value among the maximum values ​​is detected as the peak. That is, if all the points before and after the peak determination point are small, the peak determination point is detected as the peak. As a result, as shown in Figure 12B, the peak can be accurately detected even when there are multiple maximum points.

[0078] The control unit 81 performs trend removal as a preprocessing step (S124).

[0079] Figure 13 shows an example of trend removal according to one embodiment. The preprocessing unit 84 determines whether there is a slope component (trend) in the displacement data, and if there is a slope component, it removes the slope component from the displacement data. Figure 13A shows the displacement data before trend removal, and Figure 13B shows the displacement data after trend removal. Trend removal can be performed by removing the slope component (displacement component of line segment TR in the figure) from the displacement data. By performing trend removal, the type of foreign object can be determined with high accuracy. Note that although the example in Figure 13 shows a downward trend to the right, it is not limited to this, and downward trends to the left also exist.

[0080] The control unit 81 performs normalization as a preprocessing step (S125).

[0081] Figure 14 shows an example of normalization according to one embodiment. The preprocessing unit 84 normalizes the displacement data. Figure 14A shows two displacement data (indicated by the symbols O and X) before normalization. Figure 14B shows the normalized displacement data of symbol O, with the displacement data for each index normalized to a range of 0 to 1. Figure 14C also shows the normalized displacement data of symbol X, with the displacement data for each index normalized to a range of 0 to 1. Two displacement data with different displacement peaks are converted into displacement data with a peak of 1, allowing the displacement to be used as a judgment criterion to be aligned while maintaining the shape of the distribution of the displacement data.

[0082] The control unit 81 performs curve fitting (S126). Curve fitting is a process that generates a regression model by performing regression analysis on the displacement data. In this embodiment, a factor is searched so that the displacement data fits a Gaussian distribution. The Gaussian distribution f(x) is given by f(x) = a × exp{-(x-μ)} 2 / (2σ 2 It can be expressed as )}, where x is the displacement, μ is the mean, and σ 2 This represents the variance. Since the displacement data is normalized, the (maximum value - minimum value) of the Gaussian distribution is fixed at 1, the position of the maximum value is fixed at the index obtained from peak detection, and the curve fitting factor is (2σ). 2 This is the part in question.

[0083] Figure 15 shows an example of curve fitting according to one embodiment. The distribution identification unit 85 has the function of an identification unit and identifies the displacement distribution of the upper surface of the lower wafer W2 based on the displacement data. As mentioned above, in the formula representing the Gaussian distribution, the factor (2σ 2 By varying the value of ), a Gaussian curve fitting is performed on the displacement data. In the example in Figure 15, three curves represented by the symbols F1, F2, and F3 are fitted to the displacement data represented by the symbol X. In the example in Figure 15, the curve represented by the symbol F2 fits best. Note that the number of curves fitted is not limited to three.

[0084] The control unit 81 calculates the coefficient of determination (S127).

[0085] FIG. 16 is a diagram showing an example of calculating the coefficient of determination according to an embodiment. The distribution specifying unit 85 calculates the coefficient of determination. Specifically, the distribution specifying unit 85 calculates the coefficient of determination based on the first residual sum of squares of the regression model obtained by performing regression analysis on the displacement data and the second residual sum of squares based on the displacement data and the average value of the displacement data. The coefficient of determination R 2 is, R 2 = [1 - {Σ(Dmeas - Dsim) 2} / {Σ(Dmeas - Dave) 2}]. Here, {Σ(Dmeas - Dsim) 2} is the first sum of squared differences of the regression model, Dmeas is the measured displacement (displacement data), and Dsim is the displacement fitted by the regression model. The regression model is the Gaussian model F. {Σ(Dmeas - Dave) 2} is the second residual sum of squares based on the average Dave of the displacement data and the displacement data Dmeas.

[0086] The coefficient of determination is a value between 0 and 1. When the regression analysis, that is, the fitting by the Gaussian distribution, is good, the coefficient of determination becomes a large value. Conversely, when the fitting by the Gaussian distribution is not good, the coefficient of determination becomes a small value. Therefore, the distribution specifying unit 85 can determine whether the distribution of the displacement data is similar to the Gaussian distribution based on the coefficient of determination by determining the magnitude of the coefficient of determination.

[0087] The control unit 81 determines the type of foreign matter (S128). The determination unit 87 determines the type of foreign matter based on the distribution identified by the distribution identification unit 85. Specifically, if the distribution identified by the distribution identification unit 85 is similar to a Gaussian distribution, the determination unit 87 determines that it is foreign matter between the substrate (lower wafer W2) and the chuck (lower chuck 141). This prevents the lower wafer W2 from being held by the lower chuck 141 while foreign matter is attached to the non-bonding surface W2n of the lower wafer W2, thereby preventing the lower wafer W2 from being distorted, causing a bulge in the lower wafer W2, and preventing a void from forming between the lower wafer W2 and the upper wafer W1.

[0088] Figure 17 shows an example of foreign matter between the lower wafer W2 and the lower chuck 141 according to one embodiment. Figure 17A shows displacement data when there is no tilt of the wafer or chuck and foreign matter is present between the lower wafer W2 and the lower chuck 141. Figure 17B shows displacement data when foreign matter is present between the lower wafer W2 and the lower chuck 141 and at the edge of the wafer. The symbol W indicates that it is outside the wafer. According to this embodiment, the determination unit 87 can accurately determine that the foreign matter is between the lower wafer W2 and the lower chuck 141, even with the displacement data distribution shown in Figures 17A and 17B, assuming that the distribution of displacement data is similar to a Gaussian distribution.

[0089] Figure 18 shows an example of an abnormality other than foreign matter between the lower wafer W2 and the lower chuck 141 according to one embodiment. Figure 18A shows displacement data when there is no foreign matter on the non-bonding surface W2n of the lower wafer W2 but there is foreign matter on the bonding surface W2j. Figure 18B shows that there is no foreign matter on the non-bonding surface W2n of the lower wafer W2 but the shape of the trim at the edge of the lower wafer W2 is shown as abnormal data. According to this embodiment, it is possible to suppress the erroneous determination that foreign matter is present between the lower wafer W2 and the lower chuck 141 based on displacement data such as those shown in Figures 18A and 18B.

[0090] The control unit 81 determines whether there are other peaks (S129). If there are other peaks (YES in S129), it continues processing from step S124 onwards. If there are no other peaks (NO in S129), the control unit 81 terminates processing.

[0091] Although preferred embodiments have been described in detail above, the invention is not limited to the embodiments described above, and various modifications and substitutions can be made to the embodiments described above without departing from the scope of the claims. [Explanation of Symbols]

[0092] 1. Joining System 41 Joining equipment 80 Information Processing Device 81 Control Unit 83 Peak detection unit 84 Pre-processing section 85 Distribution identification part 87 Judgment section 90 Computer Programs 140 Top zipper 141 Bottom zipper 151B Upper displacement gauge

Claims

1. On the computer, By acquiring displacement data from multiple points on the surface of the substrate held in the chuck, Based on the acquired displacement data, the distribution of displacement on the surface is identified. Based on the identified distribution, the type of foreign object is determined. If the distribution resembles a Gaussian distribution, it is determined to be a foreign object between the substrate and the chuck. A computer program that executes a process.

2. On the computer, The coefficient of determination is calculated based on the first sum of squared residuals of the regression model obtained by regression analysis of the displacement data, and the second sum of squared residuals based on the displacement data and the mean value of the displacement data. Based on the calculated coefficient of determination, it is determined whether the distribution is similar to a Gaussian distribution. A computer program according to claim 1 that causes a process to be executed.

3. On the computer, Determine whether or not there is a slope component in the displacement data. If there is a tilt component, the distribution of the surface displacement is identified based on the displacement data from which the tilt component has been removed. A computer program according to claim 1 or claim 2 that causes a process to be executed.

4. On the computer, The displacement data is normalized, The distribution of surface displacement is identified based on normalized displacement data. A computer program according to any one of claims 1 to 3 that causes a process to be executed.

5. A bonding device comprising a lower chuck and an upper chuck arranged vertically apart, for bonding a substrate held by the lower chuck and a substrate held by the upper chuck, Information processing device and Equipped with, The aforementioned information processing device is An acquisition unit that acquires displacement data from multiple locations on the surface of the substrate held by the lower chuck, A specific unit that identifies the distribution of displacement on the surface based on the acquired displacement data, A determination unit that determines the type of foreign object based on the identified distribution. Equipped with, The determination unit, If the distribution resembles a Gaussian distribution, it is determined that the foreign matter is between the substrate and the lower chuck. PCB bonding system.

6. The substrate is held in the lower chuck and the upper chuck, which are positioned vertically apart from each other. Displacement data is acquired at multiple locations on the surface of the substrate held by the lower chuck. Based on the acquired displacement data, the distribution of displacement on the surface is identified. Based on the identified distribution, the type of foreign object is determined. If the distribution is similar to a Gaussian distribution, it is determined to be a foreign object between the substrate and the lower chuck. If there are no foreign objects, the substrates held by the lower chuck and the upper chuck are joined together. Board bonding method.

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