JP2015228449A - Substrate bonding method and substrate bonding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which, when bonding substrates, a void may remain between the substrates.SOLUTION: The substrate bonding method for bonding by overlapping a pair of substrates includes: an overlapping stage of mutually bringing bonding surfaces of a pair of substrates into contact with each other and overlapping them; and a degassing stage of degassing gas from between the pair of overlapped substrates. In the substrate bonding method, the degassing stage may include a stage of applying pressure to a region to be pressed that is set at part of the pair of substrates and receives a pressing force stronger than a pressing force in other regions in the pair of substrates.

Description

  The present invention relates to a substrate bonding method and a substrate bonding apparatus.

There is a method of activating and bonding the surfaces of a pair of substrates (see, for example, Patent Document 1).
Patent Document 1 JP 2013-098186 A

  Voids may be formed by the atmosphere sandwiched between the bonded substrates.

  In the first aspect of the present invention, there is provided a substrate bonding method in which a pair of substrates are stacked and bonded together, a stacking step in which the bonding surfaces of the pair of substrates are brought into contact with each other, and a pair of stacked substrates And a degassing step of degassing the gas between the substrates.

  According to a second aspect of the present invention, there is provided a substrate bonding apparatus for overlapping and bonding a pair of substrates, wherein an overlapping portion that overlaps the bonding surfaces of the pair of substrates with each other and an overlapping portion overlap each other. There is provided a substrate bonding apparatus including a deaeration unit for degassing a gas between a pair of combined substrates.

  The above summary of the present invention does not enumerate all of the features of the present invention. Sub-combinations of these feature groups can also be an invention.

1 is a schematic diagram of a bonding apparatus 100. FIG. 2 is a schematic plan view of a substrate 210. FIG. 2 is a schematic cross-sectional view of a substrate 210. FIG. FIG. 3 is a schematic cross-sectional view of a joint part 300. 3 is a flowchart showing a procedure for bonding substrates 210. FIG. 3 is a schematic cross-sectional view of a joint part 300. FIG. 3 is a schematic cross-sectional view of a joint part 300. FIG. 3 is a schematic cross-sectional view of a joint part 300. FIG. 3 is a schematic cross-sectional view of a joint part 300. FIG. 3 is a schematic cross-sectional view of a joint part 300. FIG. 3 is a schematic cross-sectional view of a joint part 300. FIG. 3 is a schematic cross-sectional view of a joint part 300. FIG. 3 is a schematic cross-sectional view of a joint part 300. 3 is a schematic cross-sectional view of a multilayer substrate 230. FIG. 3 is a schematic plan view of a laminated substrate 230. FIG. 3 is a schematic cross-sectional view of a multilayer substrate 230. FIG. 3 is a schematic plan view of a laminated substrate 230. FIG. 3 is a schematic cross-sectional view of a multilayer substrate 230. FIG. 3 is a schematic cross-sectional view of a multilayer substrate 230. FIG. FIG. 3 is a schematic cross-sectional view of a joint part 300. FIG. 3 is a schematic cross-sectional view of a joint part 300. 3 is a flowchart showing a procedure for bonding substrates 210. 3 is a schematic cross-sectional view of a multilayer substrate 230. FIG. 3 is a schematic plan view of a laminated substrate 230. FIG. 3 is a schematic plan view of a laminated substrate 230. FIG. 3 is a schematic cross-sectional view of a multilayer substrate 230. FIG. 3 is a schematic cross-sectional view of a multilayer substrate 230. FIG.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. Not all combinations of features described in the embodiments are essential for the solution of the invention.

  FIG. 1 is a schematic plan view of the bonding apparatus 100. The bonding apparatus 100 includes a housing 110, substrate cassettes 120 and 130 and a control unit 150 disposed outside the housing 110, a transfer robot 140 and a bonding unit 300 disposed inside the housing 110, and a pair of Stack and bond the substrates.

  One substrate cassette 120 accommodates the substrate 210 before bonding. The other substrate cassette 130 accommodates a laminated substrate 230 produced by bonding the substrates 210 together. Since the substrate cassettes 120 and 130 can be individually attached to and detached from the housing 110, a plurality of substrates 210 can be collectively loaded into the bonding apparatus 100 by using the substrate cassette 120. Further, by using the substrate cassette 130, a plurality of laminated substrates 230 can be carried out from the bonding apparatus 100 at a time.

  The transport robot 140 moves in the housing 110 and transports the substrate 210 from the substrate cassette 120 to the bonding unit 300. Further, the transport robot 140 transports the laminated substrate 230 formed at the joint portion 300 from the joint portion 300 to the substrate cassette 130.

  The bonding unit 300 includes a pair of stages that individually hold the pair of substrates 210, and aligns and bonds the pair of substrates 210 to each other. At least the inside of the joint 300 is temperature-controlled at a temperature close to room temperature, and the alignment accuracy is maintained.

  Since the substrate 210 is thin and fragile, the substrate 210 is held by the substrate holder 220 having higher strength and is handled together in the bonding apparatus 100. The substrate holder 220 is formed of a hard material such as alumina ceramics and is reused inside the bonding apparatus 100.

  The control unit 150 controls each unit of the bonding apparatus 100 in a coordinated manner with each other. In addition, the control unit 150 accepts a user instruction from the outside and forms a user interface that displays the operation state of the bonding apparatus 100 toward the outside.

  FIG. 2 is a schematic plan view of the substrate 210 to be bonded in the bonding apparatus 100. The substrate 210 has a single notch 214, a plurality of element regions 216, and a plurality of alignment marks 218.

  The notch 214 is provided as an index indicating the crystal orientation of the substrate 210 and the like. Therefore, the direction of the element region 216 in the substrate 210 can be detected by detecting the position of the notch 214.

  The element region 216 is periodically arranged on the surface of the substrate 210. In each of the element regions 216, a semiconductor device formed by a photolithography technique or the like is disposed. The element region 216 is also provided with pads, bumps, and the like that serve as connection terminals when the substrate 210 is electrically connected to another substrate 210, a lead frame, or the like.

  The alignment mark 218 is arranged in a blank region where the element region 216 is not formed, and serves as an index when the substrate 210 is aligned. The blank region is also provided with a scribe line 212 that is cut in the process of cutting the device region 216 into a die. Since the scribe line 212 disappears as a saw margin in the process of dicing the substrate 210, the alignment mark 218 can be provided without impairing the utilization efficiency of the substrate 210 by providing the alignment mark 218.

  In the bonding apparatus 100, as described above, an unprocessed silicon wafer, a compound semiconductor wafer, a glass substrate, and the like can be bonded in addition to the substrate 210 on which elements, circuits, terminals, and the like are formed. Bonding may be between the circuit board and the unprocessed substrate, or between the unprocessed substrates. Further, the substrate 210 to be bonded may itself be a laminated substrate 230 formed by laminating a plurality of substrates.

  The joining apparatus 100 may further include a rotation drive unit that rotates the lower stage 332 around a rotation axis perpendicular to the bottom plate 312 and a swing drive unit that swings the lower stage 332. As a result, the lower stage 332 can be made parallel to the upper stage 322, and the substrate 210 held by the lower stage 332 can be rotated to improve the alignment accuracy of the substrate 210.

  FIG. 3 is a schematic cross-sectional view of the substrate holder 220 holding the substrate 210. The substrate holder 220 has a holding part 222 and an edge part 224. The holding unit 222 has approximately the same area as the area of the substrate 210 to be held, and holds the substrate 210 by suction with an electrostatic chuck or the like. As a result, the substrate 210 is in close contact with the holding portion 222.

  The edge portion 224 extends further outward in the radial direction than the holding portion 222. Thereby, the substrate holder 220 can be handled from the outside without directly contacting the substrate 210 held by the holding portion 222 of the substrate holder 220.

  FIG. 4 is a schematic longitudinal sectional view of the bonding portion 300 in the bonding apparatus 100. The joint unit 300 includes a frame 310, an upper stage 322, and a lower stage 332.

  The frame 310 includes a bottom plate 312 and a top plate 316 that are parallel to the horizontal floor surface 301, and a plurality of columns 314 that are perpendicular to the floor plate. The bottom plate 312, the support column 314, and the top plate 316 form a rectangular frame 310 that accommodates other members of the joint portion 300.

  The upper stage 322 is also fixed downward on the lower surface of the top plate 316 in the drawing. The upper stage 322 has a holding function such as a vacuum chuck or an electrostatic chuck, and can hold the substrate holder 220 holding the substrate 210.

  A microscope 324 and an activation device 326 are fixed to the side of the upper stage 322 on the lower surface of the top plate 316. The microscope 324 can observe the upper surface of the substrate 210 held on the lower stage 332 described later. The activation device 326 generates plasma that cleans the upper surface of the substrate 210 held on the lower stage 332.

  The activation device 326 is provided to be inclined with respect to the bottom plate 312. Thereby, the plasma generated from the activation device 326 is emitted in a direction away from the microscope 324. Therefore, contamination of the microscope 324 due to debris generated from the substrate 210 irradiated with plasma is prevented.

  The lower stage 332 is mounted on the upper surface in the figure of the Y-direction drive unit 333 that is superimposed on the X-direction drive unit 331 disposed on the upper surface of the bottom plate 312. The X-direction drive unit 331 moves in the direction indicated by the arrow X in the drawing in parallel with the bottom plate 312. The Y direction drive unit 333 moves on the X direction drive unit 331 in parallel with the bottom plate 312 in the direction indicated by the arrow Y in the drawing. By combining the movements of the X-direction drive unit 331 and the Y-direction drive unit 333, the lower stage 332 can be moved two-dimensionally in parallel with the bottom plate 312.

  The lower stage 332 is supported by an elevating drive unit 338 that elevates in the direction indicated by the arrow Z perpendicular to the bottom plate 312. As a result, the lower stage 332 can move up and down with respect to the Y-direction drive unit 333.

  Note that the amount of movement of the lower stage 332 by the X-direction drive unit 331, the Y-direction drive unit 333, and the elevation drive unit 338 is accurately measured using an interferometer or the like. Further, the X direction drive unit 331 and the Y direction drive unit 333 may have a two-stage configuration of a coarse movement unit and a fine movement unit. Thereby, the movement of the substrate 210 mounted on the lower stage 332 can be bonded with high accuracy and high speed while achieving both high-accuracy alignment and high throughput.

  A microscope 334 and an activation device 326 are further mounted on the side of the lower stage 332 in the Y direction driving unit 333. The microscope 334 can observe the lower surface of the downward substrate 210 held by the upper stage 322. The activation device 336 generates plasma that cleans the lower surface of the substrate 210 held by the upper stage 322.

  Furthermore, the Y-direction drive unit 333 has a plurality of push-up pins 339 that pass through the lower stage 332 and move up and down vertically. When the push-up pin 339 protrudes upward in the drawing from the lower stage 332, the push-up pin 339 supports the edge of the substrate holder 220 and moves the substrate 210 and the substrate holder 220 up and down relative to the lower stage 332.

  FIG. 5 is a flowchart showing a bonding method of the substrate 210 that can be performed using the bonding apparatus 100 including the bonding portion 300 as described above. When the pair of substrates 210 are overlapped and bonded, the control unit 150 first carries the substrate 210 from the substrate cassette 120 to the bonding unit 300 by the transfer robot 140 (step S101). A pair of substrates 210 to be bonded is held one by one on the upper stage 322 and the lower stage 332. Hereinafter, FIG. 5 will be referred to as needed while the operation of the joint 300 will be described with reference to other drawings.

  FIG. 6 is a diagram illustrating an operation for carrying the first substrate 210 into the bonding portion 300. The control unit 150 moves the lower stage 332 to a position shifted from directly below the upper stage 322 so that the upper side of the lower stage 332 is opened. The control unit 150 waits for the substrate 210 with the push-up pin 339 raised. The control unit 150 uses the transfer robot 140 to place the substrate holder 220 holding the substrate 210 on the upper end of the push-up pin 339 protruding upward from the lower stage 332 in the drawing.

  The transfer robot 140 reverses the substrate 210 and the substrate holder 220 and places the substrate holder 220 on the upper end of the push-up pin 339 in a state where the substrate 210 is held on the lower surface of the substrate holder 220. Since the push-up pin 339 contacts the edge 224 of the substrate holder 220 that protrudes laterally from the periphery of the substrate 210, the push-up pin 339 does not contact the substrate 210 and moves the substrate 210 through the substrate holder 220. To support.

  Next, as illustrated in FIG. 7, the control unit 150 moves the lower stage 332 while maintaining the state where the substrate holder 220 is lifted by the push-up pins 339, so that the substrate holder 220 is placed directly below the upper stage 322. Move. Next, the control unit 150 further raises the push-up pin 339 and presses the upper surface of the substrate holder 220 toward the lower surface of the upper stage 322. Further, the control unit 150 causes the upper stage 322 to hold the substrate holder 220 and the substrate 210 by operating a holding mechanism such as a vacuum chuck or an electrostatic chuck.

  Next, as shown in FIG. 8, the controller 150 places the other substrate 210 held by the other substrate holder 220 on the lower stage 332. First, the lower stage 332 is returned to the initial position, the substrate holder 220 holding the substrate 210 on the upper surface is transferred to the push-up pin 339 raised from the transfer robot 140, and then the push-up pin 339 is lowered. Further, the control unit 150 operates a holding mechanism such as a vacuum chuck or an electrostatic chuck to hold the substrate holder 220 and the substrate 210 on the lower stage 332.

  Next, the control unit 150 calibrates the microscopes 324 and 334 as shown in FIG. 8 (step S102). First, by moving the X direction drive unit 331 and the Y direction drive unit 333 on which the lower stage 332 is mounted, the microscopes 324 and 334 are in a state where they can observe each other. Accordingly, the position of the lower stage 332 is detected when the positions of the microscopes 324 and 334 coincide with each other. The control unit 150 stores the position of the lower stage 332 in this state as an initial position, and uses it as a reference when controlling the amount of movement of the lower stage 332.

  Next, the control unit 150 detects the alignment marks 218 on each of the substrates 210 using the microscopes 324 and 334 (step S103). That is, as shown in FIG. 9, the control unit 150 observes the substrate 210 with the microscopes 324 and 334 while moving the lower stage 332, and detects the alignment mark 218 provided on each of the substrates 210.

  Next, since the relative position between each of the microscopes 324 and 334 and the upper stage 322 or the lower stage 332 is known in advance, the control unit 150 determines a pair based on the position of the lower stage 332 when the alignment mark 218 is detected. The relative position of the substrate 210 is calculated and stored. Accordingly, the control unit 150 determines the position of the substrate 210 so that the alignment marks 218 of the pair of substrates 210 are matched based on the initial position detected in step S102 and the relative position of the substrate 210 detected in step S103. It will be ready to match.

  Next, the control unit 150 operates the X-direction driving unit 331 and the Y-direction driving unit 333 while holding the upper position when the substrate 210 is aligned, and resets the position of the lower stage 332 to the initial position. (Step S104). Thereby, as shown in FIG. 10, the upper stage 322 and the lower stage 332 move to positions shifted from each other.

  Next, the control unit 150 activates each bonding surface of the pair of substrates 210 (step S105). That is, as shown in FIG. 11, while the activation devices 326 and 336 are operated, the lower stage 332 is moved horizontally as indicated by an arrow S in the figure and scanned by the activation devices 326 and 336. The entire bonding surface of the substrate 210 is activated. Note that in the case where elements, circuits, terminals, or the like are formed on the substrate 210, the bonding surface may be a surface on which the circuits or the like are formed.

  As a method for activating the substrate 210, for example, the substrate 210 held on the lower stage 332 is exposed to the plasma P generated by the activation device 326 supported by the top plate 316 to clean the surface of the substrate 210. To do. Further, the surface of the substrate 210 is cleaned by exposing the substrate 210 held on the upper stage 322 to the plasma P generated by the activation device 336 mounted on the Y-direction drive unit 333. As a result, the pair of substrates 210 are joined to each other when the cleaned surfaces are brought into contact with each other.

  Note that the illustrated bonding portion 300 includes an activation device 326 that is used when the substrate 210 is activated. However, it is possible to adopt a structure in which the activation device 326 of the bonding portion 300 is omitted by loading the substrate 210 activated in advance using the separately prepared activation device 326. In this case, plasma for generating the substrate 210 can be generated in a vacuum environment.

  The substrate 210 can be activated not only by plasma exposure but also by sputter etching using an inert gas. Further, the substrate 210 can be activated by ultraviolet irradiation, ozone asher or the like. Further, for example, the surface of the substrate 210 may be activated by chemical cleaning using a liquid or gas etchant.

  Next, the control unit 150 aligns the substrate 210 held on the lower stage 332 with respect to the substrate 210 held on the upper stage 322 (step S106). That is, the controller 150 matches the position in the surface direction of the alignment mark 218 of the pair of substrates 210 based on the initial position detected in step S102 and the relative position of the substrate 210 detected in step S103. The lower stage 332 is moved to align the pair of substrates 210 with each other as shown in FIG.

  Next, the control unit 150 raises the lower stage 332 to bond the pair of substrates 210 to each other (step S107). That is, as shown in FIG. 13, the lower stage 332 is raised by operating the elevating drive unit 338 to bring the bonding surfaces of the pair of substrates 210 into contact with each other. Since the bonding surfaces of the pair of substrates 210 are activated in step S105, the substrates 210 in contact with each other are bonded to each other.

  Thus, the pair of substrates 210 becomes the laminated substrate 230. However, when the substrate 210 is bonded in the atmosphere, for example, in the air, a gas may be left inside the laminated substrate 230 to form a bubble 232 called a void or the like. Therefore, in the bonding apparatus 100, the control unit 150 performs deaeration that removes the bubbles 232 from the laminated substrate 230 by the bonding unit 300 (step S108).

  FIG. 14 is a schematic cross-sectional view of the multilayer substrate 230 including the bubbles 232. FIG. 15 is a schematic plan view of the multilayer substrate 230 having bubbles shown in FIG. In the illustrated laminated substrate 230, a bubble 232 is formed at substantially the center of the laminated substrate 230.

  Note that the drawings are exaggerated, and even when the bubbles 232 are generated, the substrate 210 is hardly separated at all. However, the bonding of the substrate 210 is relatively weak in the area where the bubbles 232 are generated and in the vicinity thereof as compared with other areas.

  For this reason, when the laminated substrate 230 is pressurized for the purpose of stabilizing the bonding of the substrate 210, stress may concentrate on the weakly bonded region due to the bubbles 232, and the substrate 210 may be damaged. Further, in the region where the bubbles 232 exist, the substrate 210 is not sufficiently bonded, and when the laminated substrate 230 is diced into a die, it may be peeled off and the yield may be reduced.

  Therefore, in the bonding apparatus 100, the control unit 150 further operates the elevation drive unit 338 to pressurize the laminated substrate 230 with a pressure higher than that when the substrates 210 are bonded. As a result, the gas sandwiched between the pair of substrates 210 can be pushed out from the edge of the laminated substrate 230, and the bubbles 232 can be eliminated.

  However, when the laminated substrate 230 is pressurized while the gas is confined between the substrates 210, the substrate 210 may be damaged by the pressure of the compressed bubbles 232. Therefore, when the bubble 232 is pushed out from the inside of the multilayer substrate 230, the multilayer substrate 230 is pressurized in a state where gas is allowed to move between the pair of substrates 210 forming the multilayer substrate 230.

  In the laminated substrate 230, when the joining surface of the substrate 210 is completely joined, the movement of the gas left in the laminated substrate 230 is prevented. Therefore, when the laminated substrate 230 is pressurized for the purpose of deaeration by reducing the bonding strength of the substrate 210 at least in a part between the bubble 232 and the outer edge of the laminated substrate 230, the pressure of the compressed gas As a result, the bonding surface of the substrate 210 is locally separated to allow the gas to move.

  Therefore, for example, the degree of activation of the bonding surface of the substrate 210 in at least a part from the bubble 232 to the outer edge of the multilayer substrate 230 can be reduced, and the bonding strength immediately after bonding the substrate 210 can be reduced. . As a method for reducing the bonding strength of the substrate 210, there is a method in which the surface of the substrate 210 is left after being activated and bonded after a time has elapsed after activation. Since the degree of activation of the substrate 210 decreases with the passage of time, the bonding strength immediately after bonding can be adjusted according to the time after activation. Further, the substrate 210 may be bonded in a state where the degree of activation of the substrate is reduced by lowering the temperature of the substrate 210 by cooling or the like.

  In addition, when the bonding surface of the substrate 210 is activated, it is also possible to provide a non-activated region that is not partially activated between the position where the bubble exists and the outer edge of the laminated substrate 230 so that the gas can move. It can be mentioned as one of the techniques to make. Since the substrate 210 is not bonded in the non-activated region, the gas moves along the non-activated region when the pressure of the gas forming the bubble 232 increases. The non-activation region is continuously formed from the inside to the edge of the substrate 210.

  The non-activated region can be formed by, for example, a method in which a part of the substrate 210 covered with the mask is not activated by being exposed to plasma in a state where the part of the substrate 210 is covered with the mask. Further, by providing the non-activation region on the scribe line 212 in the substrate 210, for example, it is possible to prevent the effective area of the multilayer substrate 230 from being reduced.

  Note that even if the bonding strength immediately after bonding is low, the bonding strength may increase over time by maintaining the bonded state of the substrate 210. Further, the bonding strength may be improved by depressurizing the laminated substrate 230 after degassing the laminated substrate 230. Furthermore, the bonding strength of the substrate 210 can be improved by heating the laminated substrate 230 together with the pressurization.

  By the way, as described above, even if the bonding strength of the substrate 210 in the multilayer substrate 230 is adjusted, when the multilayer substrate 230 is pressurized, gas movement between the substrates 210 is hindered by the substrate 210 itself. May be. Therefore, when pressurizing the laminated substrate 230 for the purpose of degassing, a distribution is provided in the pressure applied to the laminated substrate 230, gas is pushed in a region where the pressure is high, and gas is moved in a region where the pressure is low. May be.

  FIG. 16 is a schematic cross-sectional view of the laminated substrate 230 sandwiched between the substrate holders 220 and 221. Although the substrate holders 220 and 221 both have a substantially constant thickness, one substrate holder 221 that supports the laminated substrate 230 from below has a flat edge portion 224, whereas the center of the holding portion 222 is raised. Has the shape.

  However, in FIG. 16, the protrusion of the holding part 222 of the substrate holder 220 is exaggerated. For example, when the holding unit 222 is pressurized at the joint 300, the substrate holder 221 and the substrate 210 do not break, and when the pressure is applied, the substrate holder 221 is elastically deformed and has a protrusion that becomes flat. Have. Therefore, when the substrate 210 held by the substrate holder 220 is pressed in a stacked state, the applied pressure is increased in the center region in the surface direction of the substrate 210.

  When the bulge of the substrate holder 221 is fine as described above, the laminated substrate 230 maintains the bonded state even when pressed. However, since the pressure force is large in the center of the substrate 210 between the substrate holders 220 and 221 and the pressure force distribution gradually decreases toward the edge portion, bubbles formed in the laminated substrate 230 are formed. 234 moves toward the edge in a region where the applied pressure is low. For this reason, when the bubble 234 passes, the substrate 210 forming the laminated substrate 230 is temporarily separated, and bonded again after the bubble 234 passes.

  FIG. 17 is a diagram showing the state of the bubbles 234 in the middle of the deaeration stage in the laminated substrate 230 pressurized using the substrate holder 221 with the center raised as described above. When the substrate 210 is joined when the substrate holder 220 is raised at the center, a pressurizing region 238 having a higher pressing force than other regions is formed near the center of the substrate 210 where the bubbles 232 are formed. Thereby, the bubble 232 is pressurized. Thus, the pressurization region 238 may be set in the region including the position of the bubble 232 in the laminated substrate 230.

  In the laminated substrate 230, the pressure around the pressurizing region 238 is relatively low with respect to the pressurizing region 238, so that the gas pressurized in the pressurizing region 238 has a low pressurizing force between the substrates 210. It is pushed out toward the peripheral edge. Thereby, inside the multilayer substrate 230, the plurality of split bubbles 234 move toward the radially outer side of the multilayer substrate 230.

  Further, in the laminated substrate 230, the bonding wave 236, which is the edge of the region where the substrates 210 are in close contact with each other, expands from the inner side of the laminated substrate 230 toward the peripheral portion following the diffusing bubbles 234. Therefore, by maintaining the state in which the laminated substrate 230 is pressurized, the pressurization region 238 expands from the inside toward the outside in the surface direction of the laminated substrate 230, and the bubbles 234 eventually form the edges of the laminated substrate 230. Extruded from.

  Prior to the degassing step, a detection step for detecting the position, size, distribution, and the like of the bubbles 234 in the laminated substrate 230 is provided, and the pressurization region is set according to the position of the bubbles 234 in the laminated substrate 230. May be. Thereby, the bubbles 234 generated in the laminated substrate 230 can be degassed more efficiently.

  The bubbles 234 in the laminated substrate 230 can be detected by, for example, removing the substrate holder 220 and observing it with a CCD camera or the like. Further, by heating or cooling the laminated substrate 230 from one surface and monitoring the temperature distribution or temperature change from the other surface, it is possible to detect the position, size, distribution, and the like of the bubbles 234 that inhibit heat transfer.

  Furthermore, the position where the bubbles 234 are generated may be predicted by measuring the shape and the like of the substrate 210 on which the multilayer substrate 230 is formed before the multilayer substrate 230 is formed. For example, when the pair of substrates 210 are aligned in the bonding portion 300, the displacement in the thickness direction of the substrate 210 is also measured in addition to the position in the surface direction of the substrate 210. The shape can be grasped. Therefore, the position where the bubbles 234 are generated when the substrates 210 are superposed can be predicted before the substrate 210 forms the laminated substrate 230.

  Thereby, it can pressurize aiming at the field where bubble 234 has occurred, and bubble 234 can be efficiently deaerated. In this case, a pressurization distribution may be generated in an apparatus for pressurizing the multilayer substrate 230, or a loading position of the multilayer substrate may be adjusted with respect to a pressurization apparatus having a predetermined pressurization distribution. In addition, by recording and accumulating the state of the detected bubble 234, it is possible to grasp the characteristics of the joint portion 300 regarding the generation of the bubble 234 and to take measures to suppress the bubble 234 generation at the joint portion 300.

  Furthermore, when a plurality of pressurization devices whose pressure distributions are known in advance are prepared, a depressurization step is performed by selecting a pressurization device having characteristics suitable for degassing the detected bubbles 234. It can also be executed. Furthermore, in the case of degassing, the efficiency and efficiency of the degassing step are increased by controlling the speed, direction, etc., of changing or moving the pressurization region according to the position, size, etc. of the detected bubble 234. be able to.

  When pressurizing the laminated substrate 230 for the purpose of degassing the bubbles 234, a pressurizing device used exclusively for the degassing step may be prepared in addition to the joint portion 300. It is preferable that the degassing pressure device used when degassing the bubbles 234 of the laminated substrate 230 has a structure in which the pressure applied to the substrate 210 is uniform or continuously changed.

  It is also preferable to perform the deaeration step in a vacuum environment or a reduced pressure environment from the viewpoint of efficient deaeration. Further, when the substrates 210 are overlapped, bubbles 234 can be generated by a gas that is easily degassed by working with carbon dioxide or the like having a lower viscosity coefficient than the atmosphere as an atmosphere. Thereby, the efficiency of a deaeration stage can be improved.

  FIG. 18 is a schematic cross-sectional view of the laminated substrate 230 deaerated as described above. As illustrated, in the laminated substrate 230, bubbles 234 are removed from between the substrates 210, and the substrate 210 is in close contact with the entire surface to form the laminated substrate 230.

  In addition, after deaeration of the laminated substrate 230, in order to improve the bonding strength of the substrate 210 in the laminated substrate 230, a pressurizing step for maintaining the state where the laminated substrate 230 is continuously pressurized may be further provided. In the above example, the substrate holder 221 located on the lower side of the laminated substrate 230 in the drawing has a raised shape. However, a raised substrate holder 221 may be used on the upper side of the laminated substrate 230 in the drawing. Furthermore, a raised substrate holder 221 may be used on both the upper and lower sides of the laminated substrate 230 in the drawing.

  Furthermore, the laminated substrate 230 including the bubbles 232 and 234 may be heated in the deaeration stage by the pressurization. Thereby, the gas that forms the bubbles 232 and 234 is expanded, and the force for pushing out the bubbles 232 and 234 from the laminated substrate 230 can be increased.

  Furthermore, the degassing step by pressurization may be performed in a reduced pressure environment or a vacuum environment. Thereby, the deaeration from the laminated substrate 230 can be further promoted. In the above example, the deaeration stage is also executed in the joint portion 300, but a vacuum environment may be separately prepared and the deaeration stage may be executed. In the bonding apparatus 100 including the facility for heating the multilayer substrate 230 in a vacuum environment, the deaeration process may be performed in a load lock that passes when the multilayer substrate 230 is carried into the vacuum environment.

  FIG. 19 is a schematic cross-sectional view illustrating another method for removing bubbles 232 from the laminated substrate 230. In the illustrated example, each of the pair of substrate holders 220 sandwiching the laminated substrate 230 has a flat shape having a certain thickness. Therefore, the pressurizing region 238 cannot be formed on the laminated substrate 230 due to the change in the thickness of the substrate holder 220.

  However, in the illustrated example, a shim sheet 226 is sandwiched between the substrate holder 220 and the laminated substrate 230 on the lower side of the laminated substrate 230 in the drawing. The shim sheet 226 is formed of a soft and thin material such as resin, copper, or aluminum. Thereby, when the flat substrate holder 220 is pressed, a pressurizing region 238 is formed in the region where the shim sheet 226 is disposed, in which a larger pressing force is applied to the laminated substrate 230 than the other regions of the laminated substrate 230. .

  Note that by changing the number of shim sheets 226 sandwiched between the laminated substrate 230 and the substrate holder 220 and the individual thicknesses, the amount of pressure applied to the pressurizing region 238 in the laminated substrate 230 can be adjusted. Further, the position of the pressurizing region 238 can be changed by changing the arrangement of the shim sheet 226 in the surface direction in the substrate holder 220.

  The laminated substrate 230 deaerated as described above is then unloaded from the base joint portion 300 (step S109). First, as shown in FIG. 20, the control unit 150 first lowers the lower stage 332 by operating the elevating drive unit 338 after stopping the upper stage holding mechanism. Thereby, the laminated substrate 230 and the pair of substrate holders 220 sandwiching the laminated substrate 230 are separated from the upper stage 322.

  Next, as shown in FIG. 21, the control unit 150 moves the lower stage 332 to the initial position by operating the X direction driving unit 331 and the Y direction driving unit 333, and then raises the push-up pin 339. The substrate holder 220 and the laminated substrate 230 are lifted. Next, the control unit 150 causes the transport robot 140 to transport the lifted substrate holder 220 and the laminated substrate 230, and causes the substrate cassette 130 to collect the laminated substrate 230. In this way, the substrate 210 carried into the bonding apparatus 100 by the substrate cassette 120 becomes a laminated substrate 230 and is carried out of the bonding apparatus 100.

  FIG. 22 is a flowchart showing another procedure for bonding the substrates 210. In FIG. 22, the steps from the loading of the substrate 210 in step S101 to the bonding of the substrate 210 in step S107 are the same as the procedure shown in FIG. Therefore, hereinafter, a stage after step S107 in which the pair of substrates 210 are joined will be described.

  In the illustrated procedure, after the substrate 210 is bonded, the control unit 150 carries the laminated substrate 230 out of the bonding unit 300 (step S201). Next, one of the pair of substrate holders 220 sandwiching the multilayer substrate 230 is removed from the multilayer substrate 230 (step S202).

  FIG. 23 is a cross-sectional view of the laminated substrate 230 with one substrate holder 220 removed. As shown in the figure, by removing one of the substrate holders 220, the laminated substrate 230 is exposed to the outside. Therefore, the position of the bubble 234 formed in the laminated substrate 230 can be detected using transmission or reflection of infrared rays, ultrasonic waves, or the like.

  In the illustrated example, it can be seen that bubbles 234 are formed in the vicinity of the peripheral edge of the multilayer substrate 230. As described above, since the position of the bubble 234 is detected before the multilayer substrate 230 is degassed, in the bonding apparatus 100, the control unit 150 can degas the multilayer substrate 230 in consideration of the position of the bubble 234 (step). S204).

  FIG. 24 is a schematic plan view of the multilayer substrate 230 for explaining a method of degassing the multilayer substrate 230 shown in FIG. As illustrated, the laminated substrate 230 has bubbles 234 in the vicinity of the peripheral edge. Therefore, on the diameter R connecting the center O and the peripheral portion of the multilayer substrate 230 through the position of the bubble 234, a part of the multilayer substrate 230 closer to the center O than the bubble 234, A pressurizing area 238 having a higher pressing force than the area is set. Thereby, when the pressurizing region 238 is pressurized, the bubbles 234 are pushed out from the radially inner side to the outer side of the laminated substrate 230.

  Next, by applying pressure to the multilayer substrate 230 in the pressurization region 238, the bubbles 234 can be pushed out of the multilayer substrate 230, and the multilayer substrate 230 can be deaerated. For example, the pressurization region 238 is formed by sticking a shim sheet 226 to a region to be the pressurization region 238 in a joint 300 that can pressurize the laminated substrate 230 by the lower stage 332 that moves up and down, or a pressurization device equivalent thereto. it can.

  FIG. 25 is a schematic plan view of the multilayer substrate 230 for explaining another method for degassing the multilayer substrate 230 shown in FIG. In the illustrated method, a linear pressurizing region 238 is set for the bubble 234 located in the vicinity of the peripheral edge of the multilayer substrate 230, and the bubble 234 is peripheral from the side closer to the center of the multilayer substrate 230 than the bubble 234. Extrude towards Thereby, the bubble 234 can be removed efficiently.

  In addition, the linear pressurization area | region 238 like illustration can be formed using a roller-shaped pressurization apparatus, for example. That is, by placing the multilayer substrate 230 on a flat and hard surface and rotating a roller longer than the diameter of the multilayer substrate 230 on the multilayer substrate 230, the bubbles 234 can be easily pushed out of the multilayer substrate 230. it can. In addition, the roller-shaped pressurizing apparatus can re-join the substrate 210 at the place where the bubbles 234 are removed, and can form the laminated substrate 230 in which the bubbles 234 are absent and the whole is in close contact.

  FIG. 26 is a schematic cross-sectional view of the multilayer substrate 230 for explaining another method for degassing the multilayer substrate 230 shown in FIG. In the illustrated method, at the position where the bubble 234 exists, a part of the laminated substrate 230 bonded is pulled away to open the bubble 234 to the outside. As a result, the gas forming the bubbles 234 is released from between the substrates 210, so that the laminated substrate 230 without the bubbles 234 can be formed by joining the separated substrates 210 again.

  Here, the laminated substrate 230 removes the bubbles 234 by pulling away the other part while keeping the part joined. Therefore, the alignment of the substrate 210 in step S106 is maintained. When a part of the multilayer substrate 230 is separated, it is preferable to work in a state where the multilayer substrate 230 is maintained in a direction parallel to the gravitational acceleration G, that is, in a vertical state. Thereby, the influence of the gravity G on the deformation of the substrates 210 is equalized with respect to the two substrates 210.

  Thus, in the laminated substrate 230, the bubbles 232 and 234 can be removed by various methods. The laminated substrate 230 deaerated in this way is collected in the substrate cassette 130 and carried out of the bonding apparatus 100 (step S205).

  Note that one of the causes of the formation of the bubbles 234 in the multilayer substrate 230 is that solid foreign matters such as dust are sandwiched between the substrates 210 forming the multilayer substrate 230. In such a case, since the substrate 210 cannot be brought into close contact with the periphery of the foreign matter, even if the laminated substrate 230 is pressurized with a large pressure, the bubble 210 may not be removed and the substrate 210 may be damaged.

  However, as described with reference to FIG. 26, by separating a part of the substrate 210 forming the laminated substrate 230, the foreign matter that causes the generation of the bubbles 234 can be removed. Thereby, the substrate 210 can be brought into close contact, and the yield of the multilayer substrate 230 can be improved.

  FIG. 27 is a schematic cross-sectional view for explaining another method for degassing the multilayer substrate 230. In the examples described so far, the bubbles 234 are deaerated by pushing them out from the edge of the laminated substrate 230. However, as shown in the figure, a deaeration hole 231 penetrating the substrate 210 may be provided in at least one of the pair of substrates 210, and the gas forming the bubbles may be discharged to the outside of the laminated substrate through the deaeration hole 231.

  The perforating step for forming the deaeration holes 231 may be before the substrate 210 is overlaid or after the substrate 210 is overlaid. The position where the deaeration holes are drilled may be a position overlapping the scribe line 212 of the substrate 210 to be removed in the final product. Further, when the deaeration holes are drilled after the substrates 210 are overlapped, the position where the deaeration holes 231 are drilled may be determined according to the position of the bubbles 234 generated in the laminated substrate 230.

  In the perforation stage, it is sufficient to form the deaeration holes 231 in any one of the substrates 210 forming the laminated substrate. However, it is planned that any of the substrates 210 is thinned by CMP or the like in a later process. In this case, it is preferable to drill the deaeration holes 231 in a substrate different from the substrate 210. Thereby, the mechanical damage by thinning with respect to the board | substrate 210 can be suppressed.

  In addition, a sealing step of sealing the deaeration holes 231 drilled in the substrate 210 after deaeration of the multilayer substrate 230 may be provided. In the sealing step, the deaeration holes 231 are sealed by, for example, filling the deaeration holes 231 with the same material as the substrate 210 or bonding a support substrate supporting the substrate 210 to the substrate 210. Thereby, intrusion of the cleaning liquid can be prevented in a subsequent process, and the metal material or the like deposited on the substrate 210 can be prevented from leaking outside the laminated substrate and contaminating the environment.

  Since the deaeration stage (step S204) can be performed by various methods as described above, one of the methods is selected according to the position, shape, size, etc. of the bubble 234 detected in step S203. May be executed. A plurality of methods can be used in combination according to the shape, size, number, and the like of the formed bubbles 232 and 234.

  Further, in the example described so far, the generated bubbles 232 and 234 are respectively pushed outward in the radial direction of the substrate 210 to deaerate the laminated substrate 230. However, as a stage in the middle of the deaeration stage, a plurality of bubbles 232 generated in the multilayer substrate may be combined to form one large bubble and then pushed out of the multilayer substrate 230. In this case, the working efficiency in the deaeration stage can be improved by moving relatively small bubbles so as to be merged with relatively large bubbles.

  In the above example, the case where the substrate 210 having the element region 216 is aligned and bonded has been described. However, even when a substrate 210 that does not require alignment and is not bonded is bonded, a highly efficient laminated substrate can be manufactured by degassing the bubbles 232 and 234.

  Further, in the above example, the substrate 210 is held by the substrate holder 220 and bonded to produce the laminated substrate 230. However, the above deaeration step can also be performed in the bonding apparatus 100 that directly handles and bonds the substrate 210 without using the substrate holder 220.

  Furthermore, in the above example, the laminated substrate 230 obtained by superimposing and bonding the substrates 210 is the processing target in the deaeration stage. However, as long as the gas is sandwiched between a pair of substrates 210 that are superimposed on each other but are not bonded, even if the substrate 210 is not bonded or temporarily bonded, it is a processing target in the deaeration stage. Can be.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

100 Bonding device, 110 Housing, 120, 130 Substrate cassette, 140 Transport robot, 150 Control unit, 210 Substrate, 212 Scribe line, 214 Notch, 216 Element area, 218 Alignment mark, 220, 221 Substrate holder, 222 Holding unit, 224 Edge portion, 226 Shim sheet, 230 Laminated substrate, 231 Deaeration hole, 232, 234 Air bubble, 236 Bonding wave, 238 Pressure area, 300 Joint portion, 301 Floor surface, 310 Frame body, 312 Bottom plate, 314 Post, 316 Top plate 322 Upper stage, 324, 334 Microscope, 326, 336 Activation device, 331 X direction drive unit, 332 Lower stage, 333 Y direction drive unit, 338 Lifting drive unit, 339 Push-up pin

Claims (30)

A substrate bonding method in which a pair of substrates are overlapped and bonded,
A superposition step of superposing the bonding surfaces of the pair of substrates in contact with each other;
A substrate bonding method comprising: a degassing step of degassing a gas between the pair of stacked substrates.   2. The substrate bonding method according to claim 1, wherein the degassing step includes a step of pressurizing a pressurizing region that is set in a part of the pair of substrates and receives a stronger pressure than the other region in the pair of substrates. .   The substrate bonding method according to claim 2, wherein the degassing step includes a step of moving the pressurization region from the inside toward the outside in the surface direction of the pair of substrates.   4. The substrate bonding method according to claim 2, wherein the deaeration step includes a step of expanding the pressurization region from the inside toward the outside in the surface direction of the pair of substrates.   The deaeration step includes a step of allowing the gas to move by providing a region having a relatively low pressure with respect to the pressurization region between the pressurization region and the outer edges of the pair of substrates. The board | substrate joining method as described in any one of Claim 2-4 containing.   6. The degassing step includes a step of allowing movement of the gas by providing a region having relatively weak activity between the pressurizing region and the outer edges of the pair of substrates. The substrate bonding method according to any one of the above.   The deaeration step includes a step of allowing the gas to move by providing a difference in activity of the bonding surface between the pressurization region and the outer edges of the pair of substrates. The substrate bonding method according to any one of claims.   8. The substrate bonding method according to claim 2, wherein the degassing step includes a step of setting the pressurization region in accordance with a position of a bubble formed by a gas between the pair of substrates. 9. .   The substrate bonding method according to claim 8, wherein the pressurizing region includes a region inside the position of the bubble with respect to a radial direction of the pair of substrates.   10. The substrate bonding method according to claim 1, wherein in the deaeration step, deaeration is performed while allowing a gas to move between the pair of substrates.   11. The deaeration step includes a step of allowing movement of the gas by pulling apart a part of the pair of substrates while overlapping a part of the pair of substrates superposed on each other. The substrate bonding method according to any one of claims.   12. The substrate bonding method according to claim 1, wherein the deaeration step includes a step of adjusting an intensity of activity of the bonding surfaces of the pair of substrates.   The substrate bonding method according to any one of claims 1 to 12, wherein the degassing step includes a step of heating a gas sandwiched between the pair of substrates.   The substrate bonding method according to claim 1, wherein the degassing step is performed under a reduced pressure environment. A detection step of detecting a position of a bubble formed by gas between the pair of substrates;
The substrate bonding method according to claim 1, wherein the deaeration step performs deaeration based on the position of the bubble detected in the detection step.   16. The degassing step includes a step of selecting at least one type of step from a plurality of types of steps prepared in advance according to a position of a bubble formed by a gas between the pair of substrates. The substrate bonding method according to any one of the above.   The substrate bonding method according to claim 1, further comprising an activation step of activating a bonding surface in each of the pair of substrates.   The substrate bonding method according to claim 17, wherein the activating step includes activating the bonding surface by exposing to the plasma.   The substrate bonding method according to claim 17, wherein the activation step includes a step of adjusting an activity strength of the bonding surface by leaving the pair of substrates after activating the bonding surface.   The method according to any one of claims 1 to 19, further comprising a pressurizing step of continuously pressurizing the pair of stacked substrates to improve the bonding strength of the pair of substrates after deaeration. Substrate bonding method.   21. The degassing step includes a perforating step of perforating a deaeration hole penetrating from between the pair of substrates to the outside of the pair of substrates in at least one of the pair of substrates. The substrate bonding method according to 1.   The substrate bonding method according to claim 21, wherein in the punching step, a deaeration hole is drilled in at least one of the pair of substrates before the pair of substrates are overlapped.   The substrate bonding method according to claim 22, wherein in the drilling step, the deaeration holes are drilled on a scribe line in the pair of substrates.   24. The perforating step includes perforating the deaeration hole at a position corresponding to a position of a bubble formed between the pair of substrates after the pair of substrates are overlapped. The substrate bonding method according to 1.   25. The substrate bonding method according to any one of claims 21 to 24, wherein, in the perforating step, the deaeration holes are perforated in a substrate that is not thinned in a subsequent process among the pair of substrates.   The substrate bonding method according to any one of claims 21 to 25, further comprising a sealing step of sealing the deaeration holes after the deaeration step.   27. The substrate bonding method according to claim 1, wherein the degassing step includes a merging step of merging a plurality of bubbles generated between the pair of substrates between the pair of substrates. .   28. The substrate bonding method according to claim 27, wherein, in the merging step, relatively small bubbles are merged with relatively large bubbles.   After the superposition step and before the deaeration step, the method further comprises a gradual dust step of detecting dust contained in bubbles formed between the pair of substrates and removing the detected dust. The substrate bonding method according to any one of claims 1 to 28. A substrate bonding apparatus for overlapping and bonding a pair of substrates,
An overlapping portion for overlapping the bonding surfaces of the pair of substrates in contact with each other;
A substrate bonding apparatus comprising: a deaeration unit that degass the gas between the pair of substrates overlapped by the overlapping unit.

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