JP2023100561A - Semiconductor manufacturing device, inspection device, and method for manufacturing semiconductor - Google Patents

Abstract

To provide a technique that can improve the accuracy of detecting flaws.SOLUTION: A semiconductor manufacturing device comprises: an imaging device that picks up an image of a die; an illuminating device that has a light source being a point light source or a line light source; and a control unit that uses the light source to irradiate a part of the die with light to form a bright field area on the die, and repeats moving the bright field area and imaging the die at a predetermined pitch to perform inspection inside the bright field area.SELECTED DRAWING: Figure 10

Description

The present disclosure relates to a semiconductor manufacturing apparatus, and is applicable to, for example, a die bonder that inspects the surface of a die.

As part of the manufacturing process of a semiconductor device, there is a process of mounting a semiconductor chip (hereinafter referred to as a die) on a wiring board, lead frame, etc. (hereinafter referred to as a substrate) and assembling a package. 2, there is a process (dicing process) of dividing a semiconductor wafer (hereinafter simply referred to as a wafer) into dies, and a die bonding process of mounting the divided dies on a substrate. A semiconductor manufacturing apparatus used in the die bonding process is a die bonder or the like. At this time, cracks, scratches, and the like (hereinafter referred to as flaws) may occur in the die in the die bonding process or a process prior thereto, such as a dicing process.

Japanese Patent Application Laid-Open No. 2020-13841

An object of the present disclosure is to provide a technique capable of improving the detection accuracy of flaws. Other problems and novel features will become apparent from the description of the specification and the accompanying drawings.

A brief outline of a representative one of the present disclosure is as follows.
That is, a semiconductor manufacturing apparatus includes an imaging device for imaging a die, an illumination device having a light source that is a point light source or a linear light source, and a part of the die that is irradiated with light from the light source to form a bright field region on the die. and a controller configured to repeatedly move the bright field region at a predetermined pitch and image the die to inspect the bright field region.

According to the present disclosure, it is possible to improve the detection accuracy of flaws.

FIG. 1 is a schematic top view showing a configuration example of a die bonder according to an embodiment. FIG. 2 is a diagram for explaining a schematic configuration when viewed from the direction of arrow A in FIG. 3 is a block diagram showing a schematic configuration of a control system of the die bonder shown in FIG. 1. FIG. FIG. 4 is a diagram showing a configuration example of a dark field inspection system in a comparative example. 5(a) and 5(b) are diagrams showing captured images in the dark field inspection system shown in FIG. FIGS. 6(a) to 6(c) are diagrams for explaining the principle of flaw detection by the bright field system. FIG. 6(d) is a diagram showing a captured image in the bright field inspection system. FIG. 6E is a diagram showing a configuration example of a bright field inspection system in a comparative example. FIG. 7A is a diagram showing a configuration example of a bright field inspection system in a comparative example. FIG. 7(b) is a diagram showing an image captured by the bright field system shown in FIG. 7(a). FIG. 8(a) is a diagram showing that a shadow is formed in a concave portion by parallel light, and FIG. 8(b) is a diagram showing that a shadow is formed in a concave portion by a point light source. FIG. 9 is a diagram showing that shadows are not formed in concave portions in the case of a surface light source. FIG. 10(a) is a diagram showing a configuration example of a bright field inspection system according to the embodiment. FIG. 10(b) is a diagram showing an image captured by the bright field system shown in FIG. 10(a). FIG. 11(a) is a diagram showing a case where a point light source is moved in the bright field inspection system shown in FIG. 10(a). FIG. 11(b) is a diagram for explaining the movement of the bright field region when the point light source is moved. FIG. 11(c) is a diagram showing the case of moving the die in the bright field inspection system shown in 10(a). FIG. 11(d) is a diagram showing a case where the camera is moved in the bright field inspection system shown in 10(a). FIG. 12 is a diagram for explaining the overlap of bright field regions. FIG. 13 is a diagram for explaining dark field inspection by the bright field inspection system shown in FIG. FIG. 14 is a diagram showing the arrangement of the wafer recognition camera and the illumination device, and the configuration of the illumination device. FIG. 15 is a timing chart showing the timing of imaging by the wafer recognition camera and image processing by the control unit. FIG. 16 is a diagram showing a configuration of coaxial lighting having a diffusion plate in surface emitting lighting. FIG. 17(a) is a diagram showing the configuration of the surface emitting illumination in the first modified example. FIG. 17(b) is a diagram showing the configuration of the surface emitting illumination in the second modified example. FIG. 18 is a diagram showing the configuration of a bright field inspection system in the third modified example. FIG. 19(a) is a flow chart showing the configuration operation of the bright field inspection system in the embodiment. FIG. 19(b) is a flow chart showing the configuration operation of the bright field inspection system in the fourth modified example.

Embodiments and modifications will be described below with reference to the drawings. However, in the following description, the same components may be denoted by the same reference numerals, and repeated descriptions may be omitted. In addition, in order to make the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual embodiment, but this is only an example, and the interpretation of the present disclosure It is not limited.

A configuration of a die bonder according to an embodiment will be described with reference to FIGS. 1 and 2. FIG.

The die bonder 10 is roughly divided into a die supply section 1, a pick-up section 2, an intermediate stage section 3, a bond section 4, a transfer section 5, a substrate supply section 6, and a substrate unloading section 7, and monitors the operation of each section. and a control unit 8 for controlling. The Y-axis direction is the front-back direction of the die bonder 10, and the X-axis direction is the left-right direction. The die supply section 1 is arranged on the front side of the die bonder 10, and the bond section 4 is arranged on the back side. Here, one or a plurality of product areas (hereinafter referred to as package areas P) are printed on the substrate S to finally form one package.

The die supply unit 1 has a wafer platform 12 that holds the wafer 11 and a push-up unit 13 that pushes up the die D from the wafer 11 as indicated by a dotted line. The wafer platform 12 is moved in the XY directions by driving means (not shown) to move the die D to be picked up to the position of the push-up unit 13 . The push-up unit 13 is vertically moved by a driving means (not shown). The wafer 11 is adhered on a dicing tape 16 and divided into a plurality of dies D. As shown in FIG. The wafer 11 is held by a wafer ring (not shown). A film-like adhesive material called a die attach film (DAF) is attached between the wafer 11 and the dicing tape 16 .

The pickup unit 2 includes a pickup head 21 that picks up the die D, a Y driving unit 23 of the pickup head that moves the pickup head 21 in the Y direction, and each driving unit (not shown) that moves the collet 22 up and down, rotates, and moves in the X direction. , and a wafer recognition camera 24 for recognizing the posture of the die D on the wafer 11 . The pick-up head 21 has a collet 22 that sucks and holds the pushed-up die D at its tip. The pickup head 21 has respective drive units (not shown) that move the collet 22 up and down, rotate it, and move it in the X direction.

The intermediate stage section 3 has an intermediate stage 31 on which the die D is temporarily placed, and a stage recognition camera 32 for recognizing the die D on the intermediate stage 31 .

The bond section 4 has a bond head 41 , a Y driving section 43 and a substrate recognition camera 44 . The bond head 41 is provided with a collet 42 that attracts and holds the die D at its tip, like the pickup head 21 . The Y driving section 43 moves the bond head 41 in the Y-axis direction. The board recognition camera 44 captures an image of a position recognition mark (not shown) in the package area P of the board S to recognize the bond position. The bonding unit 4 picks up the die D from the intermediate stage 31 and bonds the die onto the package area P of the substrate S being transported, or onto a die already bonded onto the package area P of the substrate S. Bond the dies in a stacked fashion. With such a configuration, the bond head 41 corrects the pick-up position/orientation based on the imaging data of the stage recognition camera 32 and picks up the die D from the intermediate stage 31 . Then, the bond head 41 stacks the die D on the package area P of the substrate or on the die already bonded on the package area P of the substrate S based on the imaging data of the substrate recognition camera 44 . to bond.

The transport unit 5 has a substrate transport claw 51 that grips and transports the substrate S, and a transport lane 52 along which the substrate S moves. The substrate S is moved by driving a nut (not shown) of the substrate conveying claw 51 provided on the conveying lane 52 by a ball screw (not shown) provided along the conveying lane 52 . With such a configuration, the substrate S moves from the substrate supply section 6 to the bonding position along the transport lane 52 , moves to the substrate unloading section 7 after bonding, and passes the substrate S to the substrate unloading section 7 .

The wafer recognition camera 24, the stage recognition camera 32, and the substrate recognition camera 44 are used together with an illumination device, which will be described later, to inspect the surface of the die D. FIG. The illumination device used for the surface inspection may be the same as or different from the illumination device used for posture recognition of the die D and the like.

Next, the control section 8 will be described with reference to FIG.

The control system 80 includes a control section (control device) 8 , a drive section 86 , a signal section 87 and an optical system 88 . The control section 8 is roughly divided into a control/arithmetic device 81 mainly composed of a CPU (Central Processing Unit), a storage device 82 , an input/output device 83 , a bus line 84 , and a power source section 85 . The storage device 82 includes a main storage device 82a composed of a RAM (Random Access Memory) that stores processing programs and the like, and a HDD (Hard Disk Drive) that stores control data and image data required for control. ), SSD (Solid State Drive), etc., and an auxiliary storage device 82b.

The input/output device 83 includes a monitor 83a for displaying device status, information, etc., a touch panel 83b for inputting operator's instructions, a mouse 83c for operating the monitor, and an image capturing device 83d for capturing image data from the optical system 88. and have The input/output device 83 includes a motor control device 83e for controlling a drive unit 86 such as an XY table (not shown) of the die supply unit 1 and ZY drive shafts of the bond head table, various sensors, and an illumination device to be described later. 26, and an I/O signal control device 83f for taking in or controlling a signal from a signal section 87 including a switch for controlling brightness, a volume, and the like. Optical system 88 includes wafer recognition camera 24 , stage recognition camera 32 , and substrate recognition camera 44 . The control/arithmetic unit 81 takes in necessary data through a bus line 84, performs arithmetic operations, controls the pickup head 21 and the like, and sends information to the monitor 83a and the like.

The control unit 8 stores image data captured by the wafer recognition camera 24, the stage recognition camera 32 and the substrate recognition camera 44 in the storage device 82 via the image capture device 83d. Positioning of the package area P of the die D and the substrate S and surface inspection of the die D and the substrate S are performed using the control/arithmetic unit 81 by software programmed based on the stored image data. Based on the positions of the die D and the package area P of the substrate S calculated by the control/arithmetic unit 81, the software drives the drive unit 86 via the motor control unit 83e. By this process, the die is positioned on the wafer, and the die D is bonded onto the package area P of the substrate S by operating the pickup section 2 and the driving section of the bond section 4 . The wafer recognition camera 24, the stage recognition camera 32 and the substrate recognition camera 44 used quantify light intensity and color. The wafer recognition camera 24, the stage recognition camera 32, and the substrate recognition camera 44 are also called imaging devices.

Next, the die bonding process, which is one process of the method of manufacturing a semiconductor device, will be described.

In the die bonding process of the embodiment, first, a wafer ring in which a wafer is assembled is prepared and loaded into the die bonder 10 (P1 process). The control unit 8 places the wafer ring on the wafer platform 12 and transports the wafer platform 12 to the reference position where the die D is picked up (P2 process). Then, the substrate S is prepared and loaded into the die bonder 10 (process P3). The control unit 8 places the substrate S on the transport lane 52 by the substrate supply unit 6 . The control unit 8 moves the substrate conveying claws 51 that grasp and convey the substrate S to the bonding position (step P4).

Following step P2, the control unit 8 shifts the wafer platform 12 on which the wafer 11 is placed at a predetermined pitch and horizontally holds it, thereby arranging the die D to be picked up first at the pickup position. (P5 step).

Following the P5 step, the control unit 8 captures an image of the main surface (upper surface) of the die D to be picked up by the wafer recognition camera 24, and from the acquired image, the displacement amount of the die D to be picked up from the pickup position described above. Calculate The control unit 8 moves the wafer platform 12 on which the wafer 11 is mounted based on this positional deviation amount, and accurately places the die D to be picked up at the pickup position (step P6). Then, the control unit 8 takes an image of the main surface (upper surface) of the die D to be picked up by the wafer recognition camera 24, and inspects the surface of the die D from the acquired image (P7 process).

Following the P4 step, the control unit 8 takes an image of the substrate S with the substrate recognition camera 44 and positions the substrate S based on the captured image (P8 step). Then, the control unit 8 takes an image of the board S with the board recognition camera 44, and performs surface inspection of the package area P of the board S from the acquired image (P9 process).

Following the P8 process, the control unit 8 picks up the die D from the dicing tape 16 with the pickup head 21 including the collet 22, and places it on the intermediate stage 31 (P10 process). After that, the dies D are peeled off from the dicing tape 16 one by one according to the same procedure. When all the dies D except the defective ones have been picked up, the dicing tape 16 holding the dies D in the shape of the wafer 11, the wafer ring, and the like are unloaded.

Following the step P10, the control unit 8 uses the stage recognition camera 32 to capture an image of the die placed on the intermediate stage 31 to detect the positional deviation of the die. If there is a posture deviation, the control unit 8 drives the intermediate stage 31 on a plane parallel to the mounting surface having the mounting position by a driving device (not shown) provided in the intermediate stage 31 to correct the posture deviation (P11 process). Then, the control unit 8 captures an image of the die placed on the intermediate stage 31 by the stage recognition camera 32, and inspects the surface of the die D from the acquired image (P12 process).

Following the P12 step, the control unit 8 picks up the die D from the intermediate stage 31 by the bond head 41 including the collet 42 and attaches it to the package area P of the substrate S or the die already bonded to the package area P of the substrate S. Die bond (process P13).

Following the step P13, the controller 8, after bonding the die D, inspects whether the bonding position is correct by imaging the die D and the substrate S with the substrate recognition camera 44 (step P14). At this time, the center of the die and the center of the tab are obtained, and it is inspected whether the relative positions are correct. Then, the control unit 8 takes an image of the die D and the substrate S with the substrate recognition camera 44, and performs surface inspection of the die D and the substrate S from the acquired images (P15 process).

After that, the die D is bonded to the package area P of the substrate S one by one according to the same procedure. When the bonding of one substrate is completed, the substrate conveying claw 51 moves the substrate S to the substrate unloading section 7 and delivers the substrate S to the substrate unloading section 7 (step P16). Then, the substrate S is unloaded from the die bonder 10 (step P17).

As described above, the die D is mounted on the substrate S via the die attach film and unloaded from the die bonder. After that, it is electrically connected to the electrode of the substrate S through the Au wire in a wire bonding process. When manufacturing a laminated package, the substrate S with the die D mounted thereon is carried into a die bonder, and the second die D is laminated on the die D mounted on the substrate S via a die attach film. be done. After being unloaded from the die bonder, it is electrically connected to the electrodes of the substrate S through Au wires in a wire bonding process. After the second and subsequent dies D are separated from the dicing tape 16 by the method described above, they are conveyed to the bond position and stacked on the dies D. As shown in FIG. After the above steps are repeated a predetermined number of times, the substrate S is transported to a molding step, and a plurality of dies D and Au wires are sealed with a mold resin (not shown) to complete a stacked package.

Surface inspection for scratches may be performed in at least one of the die supply section 1, the intermediate stage section 3, and the bonding section 4 where the die position is recognized, but it is more preferable to perform the inspection in all of them. If the die supply section 1 is used, the flaw can be detected quickly. If performed in the intermediate stage section 3, scratches that could not be detected in the die supply section 1 or scratches that occurred after the pick-up process (scars that did not appear before the die bonding process) can be detected before bonding. In addition, if it is performed in the bonding section 4, the damage that could not be detected in the die supply section 1 and the intermediate stage section 3 (the damage that did not become apparent before the die bonding process) or the damage that occurred after the die bonding process can be transferred to the next die. can be detected prior to lamination bonding or prior to substrate ejection.

In order to clarify the illumination for surface inspection in this embodiment, the problem of illumination for detecting flaws will be described.

When designing an inspection function for flaws in images captured by a camera, the lighting configuration should be the dark field method, in which the background is darkened and the object to be seen is brightened, and the one in which the background is brightened, and the object to be seen is darkened. There is a bright field method and a.

(1) Dark-field inspection system A dark-field inspection system using the dark-field method will be described with reference to Figs. 4, 5(a) and 5(b).

As shown in FIG. 4, a camera 101 with a lens 102 attached thereto is placed above the surface of a die D to be inspected. The field of view CV of the camera 101 includes the die D to be inspected and some or all of the surrounding die Dp adjacent thereto. The illumination device 103 is oblique illumination such as an oblique light bar, and irradiates the vicinity of the outside of the die D to be inspected with illumination light IL at a predetermined angle with respect to the optical axis OA. Here, the illumination light IL is directed toward the die Dp adjacent to the left side of the die D. As shown in FIG. The irradiation surface of the illumination device 103 extends in the Y-axis direction. The irradiation direction of the illumination light IL in the horizontal direction is the X-axis direction.

A surface inspection (dark field inspection) in a dark field inspection system is performed in an area other than the specular reflection area SRA derived from the installation position of the oblique light bar illumination. Here, the specular reflection area SRA is a specular reflection image of illumination reflected on the surface of the die D or the like exhibiting specular reflection characteristics. As shown in FIG. 5A, the specular reflection area SRA has a rectangular shape whose length in the Y-axis direction is longer than the length in the X-axis direction. The specular reflection area SRA is formed in the die Dp adjacent to the left side of the die D to be inspected. In darkfield inspection, visualization of the flaw is achieved by reflection of light on the (inside) sides of the microscopic flaw. When flaws such as cracks occur continuously in a straight line, the side faces are also continuous, and the flaws are visualized depending on the irradiation direction of the illumination light IL. Therefore, in the horizontal direction, the illumination light IL is applied from a direction different from the direction in which the scratch extends, so that the light hits the side surface.

As shown in FIG. 5A, in the horizontal direction, when the illumination light IL is irradiated from the direction (X-axis direction) perpendicular to the direction (Y-axis direction) in which the scratch Ka extends, the light can be efficiently reflected. , the blemish Ka is visible (recognizable) because it becomes brighter. On the other hand, if light is applied in the horizontal direction parallel to the extending direction (X-axis direction) of the scratch Kc, the side surface is not efficiently illuminated, and the scratch Kc becomes dark and invisible (unrecognizable). It should be noted that the flaw Kb extending along a direction having both components in the X-axis direction and the Y-axis direction is difficult to see (difficult to recognize). That is, in the dark-field inspection system shown in FIG. 4, the flaw detection sensitivity differs depending on the direction in which the flaw extends. Therefore, the flaws that can be detected are affected by the irradiation direction of the illumination light IL, and the flaws that can be detected are limited.

Also, as shown in FIG. 5B, the flaw Ka extending along the Y-axis direction can be recognized, but it gradually becomes darker in the direction of the arrow (X-axis direction). That is, the relative positional relationship from the specular reflection area SRA causes a large difference in detection sensitivity.

(2) Bright field inspection system (telecentric lens)
A bright-field inspection system using the bright-field method will be described with reference to FIGS. 6(a) to 6(e).

Since the dark-field inspection system has the above-mentioned problems, the bright-field inspection system is often used for surface inspection. The bright-field inspection system irradiates illumination light IL, which is parallel light, onto a subject surface (surface of die D) having a flat surface and specular reflection characteristics, and specularly reflected reflected light RL traces the same trajectory as illumination light IL. It is a system that condenses the light onto the lens 104 and brightens the surface of the subject. The surface of the die D is irradiated with parallel light like the locus of the illumination light IL shown in FIG. 6(a). Then, like the locus of the reflected light RL shown in FIG. 6B, the irradiated parallel light is reflected on the surface of the die D, and the reflected light RL is also parallel light. As in the case of the reflected light shown in FIG. 6C, when a concave portion RE is formed on the flat surface of the subject due to a scratch or the like, the reflected light RLu of the concave portion RE is not collected by the lens 104, and is imaged as a dark area. A dark area is detected as a flaw by image processing.

As shown in FIG. 6(d), the flaw Ka extending along the Y-axis direction becomes dark and is visible (recognizable). A flaw Kb extending along a direction that has both X- and Y-axis components is also darkened and therefore visible (recognizable). The flaw Kc extending along the X-axis direction also becomes dark and is visible (recognizable). That is, the brightfield illumination system has no orientation in the flaws it can detect, and can detect flaws extending in any direction. Also, there is no difference in sensitivity due to the relative positional relationship of illumination. For example, in the case of coaxial illumination, since recesses RE caused by scratches on the wafer surface can be detected, the bright-field method does not need to be aware of the irradiation direction of the illumination and the direction of the scratches. In addition, since the area other than the scratch is painted out brightly, it is less likely to be affected by the mask pattern transferred to the die D.

However, the bright-field inspection system irradiates the object with parallel light, and when the reflected light is collected by the lens, it is necessary to limit the light to parallel light, so a telecentric lens must be used. As shown in FIG. 6(e), a half mirror 106 is installed on the imaging plane 105 side of the lens 104, and a light source 107 is installed at the focal position to use coaxial illumination. Light is collected by lens 104 . A telecentric lens needs to have a lens diameter larger than the required field size. A lens with a large diameter has large space and weight restrictions, and is very expensive.

(3) Bright field inspection system (macro lens)
In the recent situation where the number of pixels of cameras has increased, it is possible to widen the field of view while maintaining high-definition pixel resolution. Therefore, the mainstream method is to collectively inspect a wide area with a macro lens, which is a non-telecentric lens, and reduce the movement of the field of view of the camera to speed up the inspection. Here, the macro lens has a wider field of view than its own lens diameter.

In order to obtain such a wide field of view, a high-pixel camera and a macro lens are used, but it becomes impossible to perform a bright-field appearance inspection by irradiating parallel light. This will be described with reference to FIGS. 7(a) and 7(b).

In a system whose main purpose is to recognize the posture of the die D and perform alignment (positioning), as shown in FIG. A surface emitting type coaxial illumination using a side surface light source 108 is installed to illuminate the entire surface of the die D uniformly. Since the trajectory of the condensed light in the macro lens is reverse radial, the light source of the coaxial illumination must be surface emitting in order to compensate for the expansion of the trajectory.

In the case of surface-emitting type coaxial illumination, even if the light from directly above the flaw to be inspected is reflected at a location other than directly above, the angle of incidence of the illumination light on the flaw has a certain range. light is reflected directly upward, resulting in a bright area of the scratch. This is because the surface emitting type coaxial lighting has a wide light emitting surface and has the properties of a dome lighting. That is, since surface-emitting type coaxial lighting has the property of dome lighting, even a slight unevenness caused by a scratch or the like cannot produce a shadow and is buried in a bright area. Therefore, the dark field system must be used for surface inspection of flaws and the like. In this surface-emitting type coaxial illumination, even if a lens is placed between the surface-emitting illumination and the half mirror to forcibly provide parallel light, the center is bright and the periphery is dark, as shown in FIG. Therefore, a bright field of uniform brightness cannot be obtained.

The principle of the bright field inspection system in the embodiment will be described with reference to FIGS. 8(a), 8(b) and 9. FIG.

The bright field method (bright field optical system) consists of the following three mechanisms (functions).
(A) A function that highlights the shadows of uneven scratches, etc. (B) A function that brightens the surroundings to find shadows (C) A function that uniformly brightens the entire area to secure the inspection area

Therefore, irradiation and collection of parallel light are generally required. As shown in FIG. 8(a), the parallel light PL obliquely incident on a flat surface (plane) is specularly reflected on the plane, and the reflected light RL (upward arrow indicated by a solid line) is observable. . Further, since the concave portion RE is not flat, there is no reflected light RL that becomes parallel light. Instead, the obliquely incident parallel light PL is reflected by the recess RE, and the reflected light RL′ (the upward arrow indicated by the dotted line) travels in the opposite direction to the reflected light RL, so it cannot be observed. be. That is, the shadow SH of the recess RE can be generated by the parallel light PL.

Further, as shown in FIG. 8(b), the radial light DL from the point light source PLS obliquely incident on the plane is specularly reflected on the plane, and the reflected light RL (the upward arrow indicated by the solid line) is observed. It is possible. Further, since the concave portion RE is not flat, there is no reflected light RL that becomes parallel light. Instead, the obliquely incident radiation light DL is reflected at the recess RE, and the reflected light RL′ (the upward arrow indicated by the dotted line) travels in the opposite direction to the reflected light RL, for example, and thus cannot be observed. is. In addition, there is little reflected light RL' traveling in the same direction as the reflected light RL. That is, the point light source PLS (radial light) can also generate the shadow SH of the recess RE.

However, as shown in FIG. 9, the radial light DL from the surface light source SLS incident on the plane is specularly reflected on the plane, and the reflected light RL (upward arrow indicated by a solid line) and the radiation incident on the recess RE The light DL is mixed with the reflected light RL' (upward arrow indicated by a dotted line) reflected by the recess RE, and no shadow is recognized. That is, the surface light source SLS (radial light) cannot produce a shadow in the recess RE.

Considering only the above functions (A) and (B) of the bright field system, the parallel light can rather be recognized as a point light source or a linear light source. A perfectly parallel light source can be seen as a point light source when observed from a certain point on the subject. Even if the observation position of the object is changed, the direction in which the light comes (light source direction) does not change at all. It should be noted here that the light source light does not have to be parallel, but rather a point light source or a line light source is sufficient to produce the shadow of the recessed portion due to the scratch or the like.

A bright field inspection system using a point light source in the embodiment will be described with reference to FIGS.

In the bright field inspection system according to the embodiment, for example, a macro lens is used as the lens 102 attached to the camera 101 as an imaging device. Then, as shown in FIG. 10A, an illumination device 110 is installed between the lens 102 and the die D. As shown in FIG. The illumination device 110 is point light source type coaxial illumination (coaxial epi-illumination) configured by a half mirror 106 and a point light source 109 . When the camera 101 captures an image of the surface of the die D which is flat and has the property of specular reflection, a spot-like bright field area BFA is generated as shown in FIG. 10(b). The area on the die D other than the bright field area BFA is the dark field area. The bright field area BFA has a substantially circular shape and is a small area with respect to the planar size of the die D. As shown in FIG. That is, the entire surface of the die D is covered by the plurality of bright field areas BFA. The entire surface of the die D is covered by at least two bright field areas BFA in the X and Y directions respectively. If there is a flaw K within the bright field area BFA, surface inspection (bright field inspection) can be performed by a bright field method in which the flaw K is dark and the surroundings of the flaw K are bright.

A point light source cannot realize the function (C) of the bright field method. Therefore, as shown in FIG. 11A, the point light source 109 is moved in the direction indicated by the arrow (vertical direction). As a result, the bright field area BFA moves as shown in FIG. 11(b). The movement of the point light source 109 at a predetermined pitch and the imaging of the die D by the camera 101 are repeated to inspect only the bright field area BFA. Thereby, the whole die D can be bright-field inspected.

In the bright field inspection system shown in FIG. 11A, the point light source 109 is controlled to move in order to move the position of the bright field area BFA. However, the positional movement of the bright field area BFA is not limited to this. For example, as shown in FIG. 11(c), the subject die D may be controlled to move, or as shown in FIG. 11(d), the camera 101 may be controlled to move. As shown in FIG. 11C, when the die D is moved, the point light source 109 may be fixed at a position out of the field of view of the camera 101 without using the half mirror 106 . Also, the point light source 109 shown in FIGS. 11(a), 11(c) and 11(d) may be a linear light source.

The bright field area BFA will be described with reference to FIG. 12 .

When the inspection area IA on the surface of the die D is set in a rectangular shape, the bright field area BFA on the surface of the die D is circular. Overlap and move. There is no problem if the bright field area BFA is sufficiently bright with respect to the threshold, but in the case of a point light source, the brightness uniformity of the bright field area BFA in the inspection area IA on the surface of the die D is inferior to that of the telecentric lens system. Sometimes. If there is an effect of brightness fluctuation due to the position (coordinates) in the bright field area BFA, adjust the movement pitch MP of the point light source and the inspection area IA to increase the overlap amount of the bright field area BFA and improve uniformity. can be

In addition, there may be an area in which surface inspection (dark field inspection) by a highly sensitive dark field method is possible around the bright field area BFA illuminated by the spot. A dark field inspection using this will be described with reference to FIG.

A flaw K extending tangentially to the circumference of a concentric circle is visualized with respect to the bright field area BFA. When viewed from a fixed position, it becomes possible to find flaws extending in any direction even by dark-field inspection as the bright-field area BFA moves. This also solves the problem of non-uniformity in detection sensitivity due to the extending direction of the flaw in the dark-field inspection system described above. In addition, it is possible to detect flaws that do not have clear unevenness, such as flaws that have cracks (fine cracks) but are joined on the surface, and flaws with very narrow recesses (less than 1 to 2 pixels in width). can be done. In bright-field inspection, it is difficult to detect flaws that do not have clear unevenness because the shadow image fades.

The dark field inspection by the periphery of the bright field area BFA and the bright field inspection by the bright field area BFA may be processed in parallel. This makes it possible to simultaneously detect scratches that do not produce clear unevenness, which is difficult for bright-field inspection, and pit-shaped scratches, such as scratches, which are difficult for general dark-field inspection, realizing a more sensitive inspection system. can.

The speed of cameras using recent CMOS (Complementary Metal Oxide Semiconductor) image sensors (CMOS cameras) has progressed, and for example, even cameras with 5M pixels have a frame rate of 100 or higher. If ROI (Region of Interest) processing (partial capturing processing) is added to this, the frame rate can exceed 1000, and the time required for capturing can be reduced even if capturing by dividing the area is repeated. Therefore, when a CMOS camera is used as the camera 101, even if the spot-like bright field area BFA is repeatedly imaged, it does not take much time to capture the image.

In addition, recent CMOS cameras have shifted to the back-illuminated type, and the sensitivity has improved dramatically. As a result, the exposure time can also be shortened, so even if multiple capturing is performed, it does not take much time. If high-speed processing is required, it is preferable to use a CMOS camera capable of high-speed imaging. Note that the imaging device in this embodiment is not limited to a CMOS camera, and may be a camera using a CCD (Charge Coupled Devices) image sensor, for example.

In addition, since illumination using point light source type coaxial illumination sees a specular reflection area, the reflectance is high and imaging can be performed with a shorter exposure time than the dark field method.

A specific example of the bright field inspection system shown in FIG. 10A will be described with reference to FIGS. 14 and 15, taking the optical system of the pickup unit 2 in the embodiment as an example.

As shown in FIG. 14, an objective lens 25 composed of a macro lens is attached to the wafer recognition camera 24, and an image of the main surface of the die D is taken through this objective lens 25. As shown in FIG. Between the die D and the objective lens 25 on the line connecting the wafer recognition camera 24 and the die D, an illumination device 26 having a surface emitting illumination (light source) 261 and a half mirror (half-transmitting mirror) 262 inside is arranged. ing. Irradiation light from the surface emitting illumination 261 is reflected by the half mirror 262 on the same optical axis as the wafer recognition camera 24, and the die D is irradiated with the light. The scattered light irradiated to the die D on the same optical axis as the wafer recognition camera 24 is reflected by the die D, and the specularly reflected light thereof is transmitted through the half mirror 262 and reaches the wafer recognition camera 24 to form the image of the die D. to form In other words, the illumination device 26 has a function of coaxial epi-illumination (coaxial illumination).

A surface-emitting illumination 261 in the illumination device 26 is a surface-emitting type LED light source, and includes an LED substrate 261b having a plurality of LEDs 261a as point light sources arranged in a grid pattern. Each LED 261a is configured to be individually lit (ON) and extinguished (OFF). That is, it is possible to move the light emitting position by sequentially lighting a part of the surface emitting illumination 261 .

During the surface inspection, the controller 8 forms a point light source by sequentially turning on the LEDs 261a of the lighting device 26, and is configured to move the point light source. Further, the control unit 8 is configured to turn on all the LEDs 261a of the illumination device 26 during alignment (alignment). The control unit 8 may be configured to form a linear light source by sequentially turning on the LEDs 261a column by column or row by row during the surface inspection, and to move the linear light source.

Since illumination and imaging are repeated while moving the ROI (bright field area BFA, inspection area IA), transfer from the wafer recognition camera 24 to the control unit 8 can be performed for each ROI. As a result, as shown in FIG. 15, after the transfer of the image data of the first ROI(i) is completed, the image processing of the first ROI(i) can be performed while the next ROI(ii) is being transferred. That is, image data transfer from the wafer recognition camera 24 to the control unit 8 and image processing and determination processing in the control unit 8 can be performed in parallel.

The wavelength of the light source of the illumination device 26 is not limited, but when the illumination device 26 is specialized for surface inspection, it is preferable to use short wavelength light sources such as blue, violet, and ultraviolet (UV) light.

If the brightness stability in the bright field region is somewhat inferior to that of a telecentric lens bright field inspection system, the control unit 8 uses an edge detection filter such as a differential filter or a second order differential filter in image processing to obtain a gray level difference signal. , high-pass processing may be performed to reduce the influence of fluctuations in gradation.

The optical system of the pickup section 2 (wafer recognition camera 24 and its illumination device 26) has been described, but the optical system of the intermediate stage section 3 (stage recognition camera 32 and its illumination device) and the optical system of the bond section 4 (substrate recognition camera 44 and its illumination device) have the same configuration.

Embodiments provide one or more of the following effects.

(1) Since the inspection is performed by the bright field method, it is possible to reduce the non-uniformity of the detection sensitivity depending on the extending direction of the flaw. As a result, the detection accuracy of flaws can be improved.

(2) Since inspection is performed by the bright field method, it is possible to reduce non-uniformity in detection sensitivity due to the relative positional relationship from the specular reflection area. As a result, the detection accuracy of flaws can be improved.

(3) When using a macro lens, a wide field of view is possible.

(4) Since coaxial illumination is used in the bright field inspection system, it is possible to reduce the influence of circuit patterns on the die that appear under oblique illumination.

(5) Since it is possible to improve the detection accuracy of flaws, it is possible to improve the yield of products assembled by a die bonder.

<Modification>
Some representative modifications of the embodiment are illustrated below. In the description of the modifications below, the same reference numerals as in the above-described embodiment may be used for portions having the same configurations and functions as those described in the above-described embodiment. For the description of this part, the description in the above-described embodiment can be used as appropriate within a technically consistent range. Also, part of the above-described embodiments and all or part of multiple modifications can be appropriately applied in combination within a technically consistent range.

(first modification)
Coaxial illumination in the second modification will be described with reference to FIGS. 16 and 17(a).

As shown in FIG. 16, a diffusion plate 261c may be installed between an LED substrate 261b and a half mirror 262 for coaxial illumination for alignment. Here, the diffusing plate refers to a translucent plate-like member or a milky-white color filter that diffuses the light emitted from the light source to reduce illumination unevenness. When such a coaxial illumination is used as an illumination device for surface inspection, it may not be possible to obtain a sufficiently small point light source even if the LEDs 261a are individually lit. Therefore, as shown in FIG. 17A, a bottom plate 261d may be provided between the LED substrate 261b and the diffuser plate 261c to prevent the light emitted from the LEDs 261a from spreading and to suppress the bleeding at the diffuser plate 261c. .

(Second modification)
Coaxial illumination in the second modification will be described with reference to FIGS. 16 and 17(b).

As shown in FIG. 17B, a liquid crystal panel 261e as a dynamic diffusion plate may be installed instead of the diffusion plate 261c shown in FIG. During alignment, the liquid crystal panel 261e is controlled to be opaque in order to emit diffused light. During the surface inspection, the LEDs are individually turned on to form point light sources, so the liquid crystal panel 261e is controlled to be transparent. As a result, the same illumination device can be used for alignment and surface inspection.

(Third modification)
Coaxial lighting in the third modified example will be described with reference to FIG. 18 .

A two-layer structure may be employed in which the box-type coaxial illumination shown in FIG. 14 and the box-type coaxial illumination for alignment shown in FIG. 16 are vertically stacked. The coaxial illumination shown in FIG. 14 may be arranged below or above the coaxial illumination shown in FIG.

(Fourth modification)
The operation of the bright field inspection system in the fourth modified example will be described with reference to FIGS. 19(a) and 19(b).

As shown in FIGS. 15 and 19(a), in the embodiment, imaging (S1), transfer (S2), image processing and determination processing (S3) are repeated for the number of inspection areas. In the fourth modification, as shown in FIG. 19(b), imaging (S1) and transfer (S2) are repeated for the number of inspection areas, and images of each inspection area are joined (S4), and then image processing and determination are performed. A process (S3) is performed and batch inspection is performed. However, in that case, summation synthesis, in which the data (pixel values) of the area to be inspected at each capture are added, must not be performed. This is because if the data of the area to be inspected are mixed, an image will simply be generated when the coaxial illumination of surface emission is applied.

The invention made by the present disclosure person has been specifically described above based on the embodiments and modifications, but it should be noted that the present disclosure is not limited to the above-described embodiments and modifications, and can be variously modified. Not even.

For example, in the embodiments, an example in which LEDs arranged in a matrix are sequentially turned on in coaxial illumination has been described, but LEDs as point light sources may be moved.

Further, in the embodiment, an example in which the linear light source is moved by sequentially lighting the LEDs arranged in a matrix in the coaxial lighting has been described, but the bar lighting as the linear light source may be moved.

Also, in the embodiments, an example using a macro lens has been described, but a telecentric lens may also be used.

In the embodiments, a die bonder (semiconductor manufacturing apparatus) that mounts a die on a substrate has been described as an example. It can also be applied to an inspection device that inspects the surface of a die placed on a substrate.

Further, in the embodiment, the die visual inspection recognition is performed after the die position recognition, but the die position recognition may be performed after the die visual inspection recognition.

Moreover, although the DAF is attached to the back surface of the wafer in the embodiment, the DAF may be omitted.

Also, although one pickup head and one bonding head are provided in the embodiment, two or more of each may be provided. Also, although the embodiment includes an intermediate stage, the intermediate stage may be omitted. In this case, the pickup head and the bonding head may be used together.

In addition, in the embodiment, the die is bonded with its surface facing up, but after picking up the die, the die may be turned over and bonded with the back surface of the die facing up. In this case, no intermediate stage may be provided. This device is called a flip chip bonder.

8... Control unit 10... Die bonder (semiconductor manufacturing equipment)
101 Camera (imaging device)
109... Point light source 110... Lighting device D... Die

Claims (17)

an imaging device that images the die;
a lighting device having a light source that is a point light source or a line light source;
A part of the die is irradiated with light from the light source to form a bright field region on the die, and the bright field region is repeatedly moved at a predetermined pitch and the die is imaged. a controller configured to inspect within;
A semiconductor manufacturing device comprising: In the semiconductor manufacturing apparatus of claim 1,
The semiconductor manufacturing apparatus, wherein the control unit is configured to move the bright field region by moving the light emitting position of the light source. In the semiconductor manufacturing apparatus of claim 1,
The semiconductor manufacturing apparatus, wherein the controller is configured to move the bright field region by moving the die. In the semiconductor manufacturing apparatus of claim 1,
The semiconductor manufacturing apparatus, wherein the control unit is configured to move the bright field region by moving the imaging device. In the semiconductor manufacturing apparatus of claim 1,
The semiconductor manufacturing apparatus, wherein the controller is configured to overlap and move the bright field region. In the semiconductor manufacturing apparatus of claim 1,
The semiconductor manufacturing apparatus, wherein the control unit is configured to perform a bright field inspection using the bright field area and perform a dark field inspection using a dark field area adjacent to the bright field area. In the semiconductor manufacturing apparatus of claim 1,
After transferring the image data of the first bright field region by the imaging device, the control unit performs image processing and determination of the first bright field region in parallel with the transfer of the next image data of the bright field region by the imaging device. Semiconductor manufacturing equipment configured to perform a process. In the semiconductor manufacturing apparatus according to any one of claims 1 to 7,
Further comprising a half mirror disposed between the imaging device and the die,
A semiconductor manufacturing apparatus, wherein the light source is configured to irradiate onto the die through the half mirror. In the semiconductor manufacturing apparatus of claim 1,
The lighting device is disposed between the imaging device and the die and includes a surface emitting lighting and a half mirror,
The surface-emitting lighting includes a plurality of LEDs arranged in a matrix on a plane, and each of the LEDs can be individually turned on and off,
The semiconductor manufacturing apparatus, wherein the control unit is configured to turn on a part of the plurality of LEDs to form the point light source or the linear light source. In the semiconductor manufacturing apparatus according to claim 9,
The semiconductor manufacturing apparatus, wherein the control unit is configured to move the point light source or the linear light source by changing a lighting position of the LED. In the semiconductor manufacturing apparatus according to claim 10,
The semiconductor manufacturing apparatus, wherein the control unit is configured to turn on all of the plurality of LEDs during alignment. In the semiconductor manufacturing apparatus according to claim 11,
The lighting device further comprises:
a diffusion plate provided between the surface emitting illumination and the half mirror;
a floor plate provided between the surface emitting lighting and the diffusion plate;
A semiconductor manufacturing device comprising: In the semiconductor manufacturing apparatus according to claim 11,
A semiconductor manufacturing apparatus, wherein the illumination device further includes a liquid crystal panel provided between the surface emitting illumination device and the half mirror. In the semiconductor manufacturing apparatus according to claim 10,
Further, semiconductor manufacturing comprising a second lighting device arranged between the imaging device and the die and having a surface emitting illumination, a half mirror, and a diffusion plate provided between the surface emitting illumination and the half mirror Device. In the semiconductor manufacturing apparatus of claim 1,
After the imaging device repeats the imaging of the bright field regions and the transfer of the image data for the number of bright field regions, the control unit connects the images of the bright field regions, and performs image processing and determination of the connected images. Semiconductor manufacturing equipment configured to process and batch inspect. an imaging device that images the die;
a lighting device having a light source that is a point light source or a line light source;
A part of the die is irradiated with light from the light source to form a dark field region on the die, and a bright field region smaller than the dark field region is formed on the die, and a predetermined pitch is formed. a controller configured to repeatedly move the bright field region and image the die to inspect the bright field region;
inspection device. a step of loading a wafer ring holding a plurality of dies in a wafer shape into a semiconductor manufacturing apparatus comprising an imaging device for imaging dies and an illumination device having a light source that is a point light source or a linear light source;
A part of the die is irradiated with light from the light source to form a bright field region on the die, and the bright field region is repeatedly moved at a predetermined pitch and the die is imaged. a step of inspecting the inside of
A method of manufacturing a semiconductor device comprising:

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