TWI863064B - Mounting device, inspection device, component assembly method, and semiconductor device manufacturing method - Google Patents

Abstract

[Topic] To provide a technology for "improving the accuracy of inspection of bonding materials". [Solution] A mounting device is provided with: a camera facing a bonding material having a mirror-reflecting surface; a lighting device having a light source disposed above the bonding material; and a control device configured to change the irradiation position of the light source, and inspect the bonding material based on a plurality of images obtained by the camera taking the bonding material.

Description

Mounting device, inspection device, component assembly method, and semiconductor device manufacturing method

The present disclosure relates to a mounting device, such as a die bonder that can be used with a paste as a bonding material.

Mounting devices such as die bonders are devices that use bonding materials, such as to attach (mount) components to a substrate or component. Bonding materials are, for example, resin paste or solder. Resin paste is a liquid adhesive, such as silver paste such as silver epoxy or silver acrylic. Hereinafter, resin paste will be simply referred to as paste. Components are, for example, semiconductor chips (hereinafter referred to as die) or MEMS (Micro Electro Mechanical System). Substrates are, for example, lead frames formed by wiring boards or metal sheets, glass substrates, etc.

For example, based on images obtained using a camera and a lighting device, the position of a substrate on which the paste is applied is confirmed and positioned, or whether the paste applied to the substrate is applied in a predetermined shape and only in a predetermined amount at a predetermined position is confirmed. [Prior art document] [Patent document]

[Patent Document 1] Japanese Patent Application Publication No. 2021-44466

[Problems to be solved by the present invention]

This disclosure is to provide a technology for "improving the accuracy of inspection of bonding materials". Other topics and novel features can be clearly understood from the description and attached drawings of this manual. [Means for solving the problem]

If the representative outline of the present disclosure is briefly described, it is as follows. That is, the mounting device is provided with: a camera device facing a bonding material having a mirror-like reflective surface; a lighting device having a light source disposed above the bonding material; and a control device configured to change the irradiation position of the light source, and inspect the bonding material based on a plurality of images obtained by photographing the bonding material by the camera device. [Effect of the invention]

According to the present disclosure, the accuracy of inspection of bonding materials can be improved.

The following drawings are used to explain the implementation forms. However, in the following description, the same components are sometimes given the same symbols and repeated descriptions are omitted. In addition, in order to make the description clearer, the drawings sometimes schematically show the width, thickness, shape, etc. of each part compared to the actual form, but this is only an example and does not limit the interpretation of this disclosure.

1 and 2, the structure of a die bonder in an embodiment as one aspect of a mounting device will be described.

The bonding device 10 generally comprises: a die supply section 1 for supplying a die D mounted on a substrate S; a pick-up section 2; an intermediate platform section 3; a pre-forming section 9; a bonding section 4; a conveying section 5; a substrate supply section 6; a substrate unloading section 7; and a control section (control device) 8 for monitoring and controlling the operation of each section. The Y-axis direction is the front-rear direction of the die bonder 10, and the X-axis direction is the left-right direction. The die supply section 1 is arranged at the front side of the die bonder 10, and the bonding section 4 is arranged at the rear side. Here, a plurality of product areas (hereinafter referred to as attachment areas P) that become the final package are formed on the substrate S. For example, when the substrate S is a lead frame, the attachment area P has a protrusion for mounting the die D.

The die supply unit 1 has a wafer holding table 12 for holding a wafer 11 and a stripping unit 13 indicated by a dotted line for stripping a die D from the wafer 11. The wafer holding table 12 is moved in the XY direction by a driving means not shown in the figure, and the picked-up die D is moved to the position of the stripping unit 13. The stripping unit 13 is moved in the up-down direction by a driving means not shown in the figure. The wafer 11 is attached to a dicing tape 16 and is divided into a plurality of die D. The dicing tape 16 attached to the wafer 11 is held by a wafer ring not shown in the figure.

The pickup unit 2 has a pickup head 21, a Y drive unit 23, various drives not shown in the figure, which make the collet 22 rise and fall, rotate and move in the X-axis direction, and a wafer recognition camera 24. The pickup head 21 has a collet 22 that "adsorbs and holds the peeled grain D at the front end", picks up the grain D from the grain supply unit 1 and places it on the intermediate platform 31. The Y drive unit 23 moves the pickup head 21 along the Y-axis direction. The wafer recognition camera 24 grasps the pickup position of the grain D picked up from the wafer 11.

The intermediate platform portion 3 comprises: an intermediate platform 31 for temporarily placing the die D; and a platform identification camera 32 for identifying the die D on the intermediate platform 31 .

The preforming section 9 includes a syringe 91, a driving section 93, a preforming camera 94 as an imaging device, and a preforming platform 96. The syringe 91 applies the paste to the substrate S that is transported to the preforming platform 96 by the transport section 5. The driving section 93 moves the syringe 91 along the X-axis direction, the Y-axis direction, and the up-down direction. The preforming camera 94 grasps the application position of the syringe 91, etc. When the paste is applied to the substrate S, the preforming platform 96 is raised to support the substrate S from below. The preforming platform 96 has an adsorption hole (not shown) for vacuum adsorption of the substrate S, which can fix the substrate S.

The bonding section 4 includes: a bonding head 41; a Y drive section 43; a substrate recognition camera 44; and a bonding platform 46. The bonding head 41, like the pickup head 21, includes a clamp 42 for "adsorbing and holding the die D at the front end". The Y drive section 43 moves the bonding head 41 along the Y-axis direction. The substrate recognition camera 44 photographs the position recognition mark (not shown) of the attachment area P of the substrate S to identify the bonding position. When the die D is placed on the substrate S, the bonding platform 46 is raised to support the substrate S from below. The bonding platform 46 has a suction hole (not shown) for vacuum adsorption of the substrate S, which can fix the substrate S. With such a configuration, the bonding head 41 corrects the pickup position and posture based on the image data of the stage recognition camera 32 and picks up the die D from the intermediate stage 31. Furthermore, the bonding head 41 bonds (places and connects) the die D to the attachment area P on the substrate S that is conveyed and coated with the paste based on the image data of the substrate recognition camera 44.

The conveying section 5 has a substrate conveying claw 51 for grabbing and conveying the substrate S and a conveying path 52 as a conveying path for the substrate S to move. The substrate S is moved by "a ball screw (not shown) provided along the conveying path 52 drives a nut (not shown) of the substrate conveying claw 51 provided on the conveying path 52". With such a structure, the substrate S is moved from the substrate supply section 6 along the conveying path 52 through the coating position to the bonding position, and after bonding, is moved to the substrate carrying section 7, and the substrate S is received and delivered to the substrate carrying section 7.

The control system of the die bonder 10 will be described using FIG. 3 .

The control system 80 includes: a control unit 8; a drive unit 86; a signal unit 87; and an optical system 88. The control unit 8 generally includes: a control and calculation device 81, which is mainly composed of a CPU (Central Processing Unit); a memory device 82; an input and output device 83; a bus 84; and a power supply unit 85. The memory device 82 includes: a main memory device 82a, which is composed of a RAM (Random Access Memory) storing a processing program, etc.; and an auxiliary memory device 82b, which is composed of a HDD (Hard Disk Drive) storing control data or image data required for control. The input-output device 83 includes: a display 83a for displaying device status or information, etc.; a touch panel 83b for inputting operator instructions; a mouse 83c for operating the display; and an image capture device 83d for capturing image data from an optical system 88. In addition, the input-output device 83 includes: a driver 86; a motor control device 83e for controlling the driver 86; and an I/O signal control device 83f for capturing or controlling signals from a signal unit 87.

The drive unit 86 includes the XY stage (not shown) of the die supply unit 1, the ZY drive axis of the pickup head 21 shown in FIG. 1, namely the Y drive unit 23, the ZY drive axis of the injector 91, namely the drive unit 93, and the ZY drive axis of the bonding head 41, namely the Y drive unit 43. The signal unit 87 includes switches or volumes for controlling the brightness of various sensor signals or lighting devices. The optical system 88 includes the wafer recognition camera 24, the preform camera 94, the stage recognition camera 32, and the substrate recognition camera 44 shown in FIG. 1 or FIG. 2. The control and calculation device 81 acquires necessary data via the bus 84 and performs calculations, and transmits the information to the control or display 83a of the bonding head 41 and the like.

The control unit 8 stores the image data captured by the optical system 88 in the memory device 82 via the image capture device 83d. The control and calculation device 81 is used to perform positioning of the die D and the substrate S, inspection of the coating pattern of the paste adhesive, and surface inspection of the die D and the substrate S using software programmed based on the stored image data. Based on the positions of the die D and the substrate S calculated by the control and calculation device 81, the software is used to operate the drive unit 86 via the motor control device 83e. Through this process, the die D on the wafer 11 is positioned, and the die supply unit 1 and the drive unit of the bonding unit 4 are operated to bond the die D to the substrate S. The recognition camera used in the optical system 88 digitizes light intensity or color.

4 , a bonding process (a method for manufacturing a semiconductor device) which is one of the processes for manufacturing a semiconductor device using the die bonder 10 will be described. In the following description, the operation of each unit constituting the die bonder 10 is controlled by the control unit 8 .

(Wafer loading process (process S1)) The wafer ring (not shown) is loaded into the die bonder 10. The loaded wafer ring is supplied to the die supply unit 1. Here, the dicing tape 16 is held on the wafer ring, and the dicing tape 16 is attached with the die D separated from the wafer 11.

(Substrate loading process (process S2)) The cassette (not shown) storing the substrate S is loaded into the die bonder 10. The loaded cassette is supplied to the substrate supply unit 6. The substrate S is fixed to the substrate transfer claw 51 by the substrate supply unit 6.

(Pick-up process (process S3)) After process S1, the wafer holding table 12 is moved in a manner that the desired die D can be picked up from the dicing tape 16. The die D is photographed by the wafer recognition camera 24, and the positioning and surface inspection of the die D are performed based on the image data obtained by the photographing.

The positioned die D is peeled off from the dicing tape 16 by the peeling unit 13 and the pickup head 21. The die D peeled off from the dicing tape 16 is sucked and held by the collet 22 disposed on the pickup head 21 and is transported to the intermediate platform 31 for placement.

The die D on the intermediate platform 31 is photographed by the platform recognition camera 32, and the positioning and surface inspection of the die D are performed based on the image data obtained by the photographing. The offset (X, Y, θ directions) of the die D on the intermediate platform 31 relative to the die position reference point of the die bonder 10 is calculated by image processing, and the positioning is performed. In addition, the die position reference point is the predetermined position of the intermediate platform 31 that is maintained as the initial setting of the device. The surface inspection of the die D is performed by image processing of the image data.

The pick-up head 21 that transports the die D to the intermediate platform 31 returns to the die supply unit 1. According to the above sequence, the next die D is peeled off from the dicing tape 16, and thereafter, the die D is peeled off from the dicing tape 16 one by one according to the same sequence.

(Preforming process (process S4)) After process S2, the substrate S is conveyed to the preforming platform 96 by the conveying unit 5. The surface of the substrate S before coating is photographed by the preforming camera 94, and the surface to be coated with the paste is confirmed based on the image data obtained by the photographing. If there is no problem with the surface to be coated with the paste, the position of the substrate S supported by the preforming platform 96 to coat the paste is confirmed and positioned. Positioning is performed by pattern matching, etc., in the same way as the joint unit 4.

The paste is ejected from the nozzle at the front end of the syringe 91 and applied according to the trajectory of the nozzle. The nozzle is driven on the XYZ axis according to the shape to be applied by the drive unit 93, and the nozzle trajectory is used to draw a free trajectory such as an x mark shape or a cross shape to apply (draw). In addition, at the front end of the syringe 91, in addition to the nozzle, a template head can also be set.

The applied paste is photographed by the pre-forming camera 94. Based on the image obtained by the photographing, it is confirmed whether the paste is applied correctly, and the applied paste is inspected (appearance inspection). That is, in the appearance inspection, it is confirmed whether the applied paste is applied in a predetermined shape and only in a predetermined amount at a predetermined position. The inspection content includes, for example, the presence or absence of paste, the coating area, the coating shape (insufficient, overflow), etc. The inspection is performed by a method of counting the number of pixels after separating the paste area by binarization, a method of comparing the difference, a method of comparing the scores based on pattern matching, and a shape determination based on contour extraction.

(Joining process (process S5)) If there is no problem with coating, the substrate S is transported to the joining platform 46 by the transport unit 5. The substrate S placed on the joining platform 46 is photographed by the substrate recognition camera 44, and image data is obtained by photographing. By performing image processing on the image data, the offset (X, Y, θ direction) of the substrate S relative to the substrate position reference point of the die bonder 10 is calculated. In addition, the substrate position reference point is the initial setting of the device by pre-setting the predetermined position of the joining unit 4.

The absorption position of the bonding head 41 is corrected based on the offset of the die D on the intermediate platform 31 calculated in step S3, and the die D is absorbed by the collet 42. The die D is bonded to a predetermined position of the substrate S supported by the bonding platform 46 by the bonding head 41 that absorbs the die D from the intermediate platform 31. The die D bonded to the substrate S is photographed by the substrate recognition camera 44, and based on the image data obtained by the photographing, it is checked whether the die D is bonded to the desired position.

The bonding head 41 that has bonded the die D to the substrate S returns to the intermediate platform 31. According to the above sequence, the next die D is picked up from the intermediate platform 31 and bonded to the substrate S. The above steps are repeated until the die D is bonded to all the attachment areas P of the substrate S.

(Substrate unloading process (process S6)) The substrate S with the die D bonded thereto is transported to the substrate unloading unit 7. The substrate S with the die D bonded thereto is removed from the substrate transport claw 51 by the substrate unloading unit 7 and stored in the cassette. The cassette storing the substrate S is unloaded from the die bonder 10.

As described above, the die D is mounted on the substrate S and removed from the die bonder 10. The substrate S with the die D mounted thereon is transported to the wire bonding process, where the electrode of the die D is electrically connected to the electrode of the substrate S via the Au wire or the like. The substrate S is transported to the molding process, where the die D and the Au wire are sealed with a molding resin (not shown), thereby completing the packaging.

The lighting device used when photographing the paste PA by the preform camera 94 will be described using FIG. 5 .

The preform camera 94 is disposed above the paste PA applied on the substrate S. The lighting device 95 is disposed below the preform camera 94 and above the paste PA. The preform camera 94, the lighting device 95 and the control unit 8 constitute a device for inspecting the amount of bonding material.

The pre-forming camera 94 is preferably a camera (CMOS camera) using a CMOS (Complementary Metal Oxide Semiconductor) image sensor capable of high-speed transmission. The pre-forming camera 94 is more preferably a high-sensitivity back-illuminated CMOS camera. In addition, the pre-forming camera 94 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.

The lighting device 95 is configured by arranging a plurality of light sources 95a to 95l in a dome (hemispherical shell) shape. In this way, the light source is multi-pointed. Each light source 95a to 95l can be turned on and off individually.

The incident angle of the irradiation light from the light sources 95e~95h to the paste PA (the angle relative to the optical axis of the preform camera 94) is smaller than the incident angle of the irradiation light from the light sources 95a~95d to the paste PA. The incident angle of the irradiation light from the light sources 95i~95l is smaller than the incident angle of the irradiation light from the light sources 95e~95h to the paste PA. For example, the light sources 95a~95d are arranged in the same horizontal plane. The light sources 95e~95h are arranged in the same horizontal plane above the light sources 95a~95d. The light sources 95i~95l are arranged in the same horizontal plane above the light sources 95e~95h.

Each of the light sources 95a to 95l is a point light source. Each of the light sources 95a to 95l is, for example, an LED (Light Emitting Diode) light source output by an optical fiber having a diameter of about 1 mm or less, preferably about several hundred μm. In addition, the lighting device 95 may be, for example, a dome lighting device that "arranges a plurality of light sources composed of LEDs (Light Emitting Diodes) inside a dome". In this case, the light emitting position of the lighting light is changed by turning off/on the LEDs individually. In addition, the multi-point light source may also be achieved by moving one or more light sources. For example, in the case of moving a plurality of light sources, the lighting device 95 is configured to include light sources 95a, 95e, and 95i, and the light sources 95a, 95e, and 95i move within the same plane.

The control unit 8 obtains the position where the irradiated light from each light source of the lighting device 95 is directly reflected (the reflection position of the direct light), and measures the shape of the liquid surface, i.e., the paste PA, from the obtained reflection position of the direct light. Bright spots are formed at the reflection positions of the direct light. The more light sources there are, the higher the resolution can be measured.

A method for measuring the shape of paste PA will be described using FIGS. 6( a ), 6( b ), 6( c ), 7( a ), 7( b ), 8 , and 9 .

(Photographed) Figure 6(a) shows an image when only light source 95a is on, Figure 6(b) shows an image when only light source 95b is on, and Figure 6(c) shows an image when only light source 95c is on.

As shown in Fig. 6 (a) to Fig. 6 (c), the control unit 8 turns on the light sources 95a, 95b, and 95c one by one, and uses the pre-forming camera 94 to photograph the bright spots BS1, BS2, and BS3 formed by direct reflection on the surface of the paste PA for each light source. The light sources 95d to 951 are also turned on one by one to photograph the paste PA. In the figure, the paste PA is shown in black, and the bright spots BS1, BS2, and BS3 are shown in white.

(Calculation of bright spot center) As shown in Fig. 6(a) to Fig. 6(c), since bright spots BS1, BS2, and BS3 are not points but shapes with width such as ellipses, the control unit 8 calculates the center of the bright spot (bright spot center) in each image. The calculated bright spot center is used as the bright spot position. Regarding the method of determining the bright spot center, in addition to the simple regional center (the center of the upper and lower or left and right extreme points), it can also be the center of gravity of the deformation state of the shape, the maximum luminosity point, the center point of the maximum inscribed circle, etc.

In addition, the area of the light emitting surface of the light source is preferably as small as possible so that the bright spot is as close to a point as possible. In other words, the viewing angle of the light source is preferably as small as possible when viewed from the reflection position of the direct light that forms the bright spot. In addition, the light source is preferably as bright as possible. The calculation of the bright spot center is not performed every time shooting, but can be performed uniformly after all shooting.

(Calculation of paste shape) The control unit 8 calculates the reflection point in three-dimensional space from the bright spot center (bright spot position) in the calculated two-dimensional image to obtain the shape of the paste. In order not to complicate the explanation, the following is an example of the light source being located on the X-axis.

A method for calculating the angle of the reflecting surface on which the bright spot is formed will be described using FIG. 7( a ) and FIG. 7( b ).

The preforming camera 94 is located far enough away from the paste PA so that the preforming camera 94 is always in the same direction when viewed from the paste PA. In other words, the distance between the preforming camera 94 and the paste PA (shooting distance) is large enough relative to the size of the paste PA. For example, the shooting distance is about 100 mm, and the paste width is about 0.3 to 10 mm. In FIG. 7 (a), for the sake of convenience, although the preforming camera 94 is located directly above the paste PA, the direction of the preforming camera 94 does not necessarily have to be directly above the paste PA. As long as the entire area of the paste to be photographed can be approximately located in a fixed direction, it will be sufficient.

One of the light sources 95a~95l shown in Figure 5 is described as the light source LS. The light source LS is a point light source, and because it is sufficiently far away from the paste PA, it is regarded as a parallel light source. The irradiation light from the light source LS is directed toward the center O of the field of view of the preformed camera 94 on the surface of the substrate S. The position of the light source LS from the field of view center O and the position of the preformed camera 94 are known. Since the light source LS is a parallel light, the direction of travel of the irradiation light is known. In addition, the direction of travel of the reflected light in the paste PA is a vertical direction and is known. That is, the vector "starting from the center O and ending at the position of the light source LS" and the vector "starting from the center O and ending at the position of the preformed camera 94" are known. Therefore, since the angle (θ) formed by the irradiation light and the reflected light of the light source LS is the angle formed by the two vectors, it can be calculated.

When the angle of the reflection surface (normal direction of the reflection surface) that forms the bright spot BS by the light source LS is set to φ, it can be calculated from θ by the law of reflection. That is, φ=θ/2. The calculated φ is the angle formed with the vertical direction, and is the angle formed by the direction of the tangent TD of the reflection surface (contact surface direction) and the X direction (horizontal plane) (the slope of the tangent TD).

As shown in FIG. 7( b ), when the distance from the center O of the field of view CV of the pre-forming camera 94 to the bright spot BS formed by the light source LS is set as X _BS , X _BS can be calculated from the image captured by the pre-forming camera 94 .

Next, a method for calculating the position of a bright spot in the Z direction (Z position, height) will be described using FIG. 8 and FIG. 9 .

As shown in Fig. 8, the formation of four bright spots BSa, BSb, BSc, and BSd is described. The bright spot positions of the four bright spots BSa, BSb, BSc, and BSd from the center O of the field of view CV of the pre-forming camera 94 are denoted by Xa, Xb, Xc, and Xd.

As shown in FIG. 9 , the position where bright spot BSa is formed and the tangent line TDa of the reflection surface forming bright spot BSa are arranged on the X-axis. Similarly, the position where bright spot BSb is formed and the tangent line TDb of the reflection surface forming bright spot BSb are arranged on the X-axis, the position where bright spot BSc is formed and the tangent line TDc of the reflection surface forming bright spot BSc are arranged on the X-axis, and the position where bright spot BSd is formed and the tangent line TDd of the reflection surface forming bright spot BSd are arranged on the X-axis. Here, when the slopes of the tangent lines TDa, TDb, TDc, and TDd are set to φa, φb, φc, and φd, respectively, φa＜φb＜φc＜φd. In general, the inclination of the surface of the paste relative to the substrate increases as it is farther away from the center or the center line.

The Z positions of the bright points BSa, BSb and the tangent lines TDa, TDb are arranged in such a way that the intersection IPa of the two tangent lines TDa, TDb of the adjacent bright points BSa, BSb is located at the middle point CPa of the two bright points BSa, BSb. Here, the middle point CPa is located at a distance of O|Xa+(Xb-Xa)/2| from the center of the field of view.

The Z positions of the bright points BSb, BSc and the tangent lines TDb, TDc are arranged so that the intersection point IPb of the two tangent lines TDb, TDc is located at the middle point CPb of the two bright points BSb, BSc. Here, the middle point CPb is located at a distance of O|Xb+(Xc-Xb)/2| from the center of the field of view.

The Z positions of the bright points BSc, BSd and the tangent lines TDc, TDd are arranged so that the intersection point IPc of the two tangent lines TDc, TDd is located at the middle point CPc of the two bright points BSc, BSd. Here, the middle point CPc is located at a distance of O|Xc+(Xd-Xc)/2| from the center of the field of view.

In this way, since the Z positions of the intersection points IPa~IPc and the bright points BSa~BSd can be determined, the shape (volume) of the paste can be approximately calculated from the polygon connecting the intersection points IPa~IPc and the bright points BSa~BSd. In addition, the above interpolation method is an example, and other methods such as spline interpolation or Lagrange interpolation can also be used.

The Z position value of the bright spot on the outermost side can be the offset value of all bright spots. As a die bonder, since it is sufficient to monitor the relative amount, the Z position value of the bright spot BSd on the outermost side can be set to 0, or the Z position value can be set to a predetermined value other than 0, as shown in FIG8 . That is, the Z position value of the bright spot on the outermost side can be temporarily determined. In addition, the reflection surface of the boundary point of the paste can be temporarily determined to be a fixed angle (vertical or nearly vertical value, etc.).

The light source LS can also be moved in a direction close to the horizontal plane including the substrate surface to search for the position where the bright spot contacts the paste contour surface (the bright spot with the largest φ can be photographed). In this way, the height of the outermost bright spot can be approximated to 0, so the absolute amount of the paste can be measured.

In order to further clarify the present embodiment, several comparative examples are described.

(First Comparative Example) The first comparative example is described using Figures 10(a), 10(b), and 10(c).

In the lighting device shown in FIG5 , it is considered that all light sources 95a to 951 are turned on to form a plurality of bright spots. This is referred to as the first comparative example. In the first comparative example, as shown in FIG10( a ), it is preferred that the reflection position of each light source, i.e., the bright spot, can be roughly predicted in advance. Here, bright spot BS1 is a bright spot formed by light source 95a, bright spot BS2 is a bright spot formed by light source 95b, bright spot BS3 is a bright spot formed by light source 95c, and bright spot BS4 is a bright spot formed by light source 95d.

However, as shown in FIG. 10( b ), when the shape of the subject to be measured is unstable, the positions of the bright spots represented by white are irregular (related to the light source), making it difficult to determine which bright spot corresponds to which light source, and measurement cannot be performed.

Furthermore, as shown in FIG. 10( c ), when the shape of the paste is complex, the bright spot generated by one light source is not limited to one, and the multi-point light source makes it more difficult to distinguish the combination of the light source and the bright spot.

In the implementation form, each light source is turned on individually and photographed each time, thereby maintaining the correlation between the light source and the bright spot.

(Second Comparative Example) In order to solve the above problem of the first comparative example, it is considered to ensure the correlation between the light source and the bright spot by "changing the wavelength of each light source and setting a camera that can perform color recognition". This is called the second comparative example. Since the second comparative example is limited to the number of colors when distinguishing by color, there is an upper limit to the number of points of the multi-point light source. In addition, in the second comparative example, it is affected by the spectral reflection characteristics (reflection spectrum) of the subject, so there is a situation where it cannot be used depending on the color of the colored liquid.

In the embodiment, each light source is individually turned on and photographed each time, thereby maintaining the correlation between the light source and the bright spot. Thus, since there is no need to change the wavelength of each light source, the problem of the second comparative example does not exist.

(Third Comparative Example) The third comparative example will be described using Figures 11 and 12.

Consider the following method: Use a camera (an upper camera) placed above the paste to photograph the paste and measure its area, thereby checking the amount of paste applied. This is called the third comparative example. However, in the photographing from the upper camera, only the coating area is simply known. For example, the viscosity of the paste varies depending on the temperature, and as a result, the surface tension is different. Therefore, as shown in the side view of Figure 11, even if the angle (contact angle) between the paste PA and the substrate S is different, as shown in the image of Figure 11, the coating area can be the same. In other words, even if the coating area is the same, the coating amount (volume or mass) varies and is not constant due to differences in the protrusion state caused by surface tension, etc.

For example, in the case of micro-crystals (e.g., about 1 mm square), although a micro-amount (a micro-area smaller than the plane area of the micro-crystal) of paste is applied, the amount of paste applied is easily affected by a slight change in the height of the syringe during application, etc. Also, in the case of application of micro-areas, when the amount of application is measured by the third comparative example, the measured amount may be significantly different from the actual amount due to the influence of the surface tension of the paste PA, etc. When the amount of application differs for this reason, as shown in FIG. 12 , the overflow amount (HD) or the climbing amount (HA) of the paste PA when the crystal is bonded to the substrate may be affected. In tiny grains, even a slight difference in the coating amount will increase the variation rate, which will greatly affect the bonding process.

The miniaturization of micro-crystals is further developed. In addition to simple crystals, they are becoming more complex with MEMS structures. Pastes also require a small amount of coating technology, and the coating amount control is also required to be more accurate. Therefore, in terms of coating amount control, it is also required to be able to measure or check the coating amount with the die bonder itself that performs the coating process.

Since the coating amount of the paste can be calculated more accurately in the embodiment, the coating amount of fine grains can be measured or inspected, and more accurate coating amount control can be performed.

(Other Comparative Examples) The following methods are also considered: "Changing the focus position of the camera placed vertically (directly above) and adding the focus positions to infer the shape" (the fourth comparative example), "using a stereo camera (plural cameras) to perform three-dimensional recognition" (the fifth comparative example), and "setting slits in the parallel light source and using a zebra light source that can form stripes to project stripes" (the sixth comparative example).

Since the methods of the fourth to sixth comparative examples utilize images to find the position of the surface, they are based on the premise that the object surface is diffusely reflected. In the case of an object dominated by mirror reflection, such as a liquid surface such as a paste, the positional relationship or image of the reflected light source is strongly affected, and it is difficult to infer the position of the reflecting surface.

In a transparent liquid, the light from the inside of the liquid surface almost dominates. Since the mirror-reflected light on the liquid surface is out of focus, only the slightly diffused light on the surface can be focused. However, the amount of light is exponentially greater than the reflected light from the inside and is buried in the light, and as a result, it is impossible to focus on the surface in the fourth or fifth comparative examples. In addition to transparent and semi-transparent pastes, there are some that contain fine particles of metal such as silver inside, and some that are difficult to detect on the surface.

In the method of the sixth comparative example, since the diffuse reflector is not determined by the law of reflection, the image is captured as stripes depending on the position illuminated by the zebra light source formed by the parallel light source. The hemispherical part formed by the paste, etc., forms a stripe pattern depending on the arrival position of the light from the light source. In contrast, in the case of mirror reflection, the law of reflection is followed, so when the parallel light reaches the surface, its reflected light may not be gathered on the camera. Therefore, in the method of the sixth comparative example, in the case of mirror reflection, only the background scenery is seen to bend on the surface.

The embodiment can detect the surface of a paste that is a mirror-reflecting liquid or the surface of a paste that is "transparent or semi-transparent and contains fine particles of metal such as silver inside." In addition, the method of the embodiment can be applied not only to the paste but also to the detection of the surface of a mirror-reflecting metal such as solder. That is, the volume of a three-dimensional liquid or metal with a mirror-reflecting surface can be measured or inspected.

In the embodiment, since the amount of the paste applied can be monitored, one or more of the following effects are achieved.

(1) The coating amount can be checked and measured each time the coating is applied or at regular intervals during the production process.

(2) In the production process, based on the coating amount measured by (1) above, an alarm or error of abnormal coating amount is generated, or feedback of increase or decrease in coating amount is provided, thereby stabilizing the coating amount.

(3) By means of the above-mentioned (2), the amount of overflow or rise of the paste after joining can be stabilized.

(4) The yield rate of die bonder assembled products can be improved.

Although the disclosure completed by the inventors has been specifically described above based on the embodiments, the disclosure is not limited to the above embodiments and various modifications are possible, needless to say.

For example, in the embodiment, although the measurement of the shape just after applying the paste (the amount of coating) is described, it can be applied to the wettability inspection of the paste after bonding (the amount of paste overflow or climbing) or the measurement of the solder shape and the solder lead inspection (the amount of solder overflow or climbing).

Furthermore, although the embodiment describes an example of a point light source as an illumination device, a ring-shaped illumination device may also be used as the illumination device. This allows an image such as contour lines at equal tilt angles to be obtained on the surface of the paste, and the inspection speed can be increased.

Furthermore, in the embodiment, although the circular paste in a plan view is described, it can also be applied to the inspection of a paste formed by coating (pen light, drawing) while moving the nozzle.

Furthermore, in the embodiment, although an example of inspection using a pre-forming camera is described, inspection may also be performed using a substrate recognition camera or a bonding camera.

In the embodiment, although a point light source is described as an example of an illumination device, it is also possible to add a point light source or a coaxial illumination of a parallel light source for inspection. In this way, an image of φ=0 can be obtained, and an outer contour inspection can be performed.

Furthermore, in the implementation form, although the example of "providing an intermediate platform portion 3 between the grain supply portion 1 and the bonding portion 4, placing the grain D picked up from the grain supply portion 1 on the intermediate platform 31 by the pickup head 21, and picking up the grain D from the intermediate platform 31 again by the bonding head 41 and bonding it to the conveyed substrate S" is described, the grain D picked up from the grain supply portion 1 can also be bonded to the substrate S by the bonding head 41.

Furthermore, in the embodiment, although the die bonder is described as an example, the present invention can also be applied to a flip chip bonder or a chip mounter.

8: Control unit (control device) 10: Die bonder (installation device) 94: Preform camera (camera) 95: Lighting device 95a~95l: Light source PA: Paste (bonding material)

[FIG. 1] FIG. 1 is a top view schematically showing a die bonder in an embodiment. [FIG. 2] FIG. 2 is a diagram illustrating a schematic configuration when viewed from the direction of arrow A in FIG. 1. [FIG. 3] FIG. 3 is a block diagram schematically showing a control system of the die bonder shown in FIG. 1. [FIG. 4] FIG. 4 is a flow chart showing a method for manufacturing a semiconductor device using the die bonder shown in FIG. 1. [FIG. 5] FIG. 5 is a diagram showing a preformed camera, an illumination device, and a paste applied to a substrate in an embodiment. [FIG. 6] FIG. 6(a) to FIG. 6(c) are diagrams showing images of a paste when only one light source of the illumination device shown in FIG. 5 is on. [FIG. 7] FIG. 7(a) is a diagram showing the positional relationship among the preformed camera, the light source, and the paste. Fig. 7(b) is a diagram showing the position of the bright spot in the field of view of the pre-forming camera. [Fig. 8] Fig. 8 is a diagram showing the position of the bright spot in the field of view of the pre-forming camera. [Fig. 9] Fig. 9 is a diagram for explaining the method of "calculating the Z position of the bright spot based on the coordinates of the bright spot on the plane and its tangent direction". [Fig. 10] Fig. 10(a) is a diagram showing an image when there is a correlation between the light source and the bright spot. Fig. 10(b) is a diagram showing an image when the correlation between the light source and the bright spot is less. Fig. 10(c) is a diagram showing an image when the shape of the paste is complex. [Fig. 11] Fig. 11 is a diagram showing the side and top images of the applied paste. [Fig. 12] Fig. 12 is a diagram showing the overflow and climbing of the paste.

S1: Wafer loading

S2: Substrate loading

S3: Pickup

S4: Pre-forming

S5: Joining

S6: Substrate removal

Claims (11)

A mounting device is characterized by comprising: a camera facing a bonding material having a mirror-like reflective surface; an illumination device having a light source disposed above the bonding material; and a control device configured to change the irradiation position of the light source, and inspect the bonding material based on a plurality of images obtained by photographing the bonding material with the camera, wherein the irradiation position of the light source is changed to be configured in a dome shape. As in claim 1, the control device is configured to calculate the positions of the multiple bright spots in the image based on the multiple images of "reflection points of the irradiated light from the light source on the surface of the bonding material, i.e., bright spots", calculate the positions of the multiple bright spots in space based on the multiple bright spot positions in the image, and calculate the shape of the bonding material based on the bright spot positions in space. As in the installation device of claim 2, wherein the control device is configured to calculate the bright spot position in the space based on the bright spot position in the image, the position of the light source, and the position of the camera. The mounting device of claim 3, wherein the control device is configured to: calculate the normal direction of the surface of the bonding material at the bright spot position in the image based on the bright spot position in the image, the position of the light source and the position of the camera, calculate the tangent direction of the surface of the bonding material at the bright spot position in the image based on the normal direction, calculate the bright spot position in the space based on the bright spot position in the image and the tangent direction, and calculate the shape of the bonding material based on the tangent direction and the bright spot position in the space. As in claim 4, the control device is configured to change the irradiation position by moving the light source. As in claim 5, the control device is configured to retrieve the position where the bright spot contacts the contour surface of the bonding material. As in claim 4, the control device is configured to temporarily determine the height of the bright spot formed on the outermost side of the bonding material or the tangent direction of the surface of the bonding material at the bright spot position of the boundary point of the bonding material to a predetermined value. As in claim 1, the lighting device comprises: a plurality of light sources that can be turned on and off individually, and the control device is configured to change the irradiation position by turning on and off the plurality of light sources. An inspection device is characterized by comprising: a camera facing a bonding material having a mirror-like reflective surface; an illumination device having a light source disposed above the bonding material; and a control device configured to change the irradiation position of the light source, and inspect the bonding material based on a plurality of images obtained by the camera photographing the bonding material, wherein the irradiation position of the light source is changed to be configured in a dome shape. A component assembly method, characterized by having a process of "carrying a substrate into a mounting device", the mounting device having: a camera facing a bonding material having a mirror reflective surface; and a lighting device having a light source disposed above the bonding material; a process of "applying the bonding material to the substrate"; a process of "changing the irradiation position of the light source, and inspecting the bonding material based on a plurality of images obtained by photographing the bonding material with the camera"; and a process of "attaching the component to the substrate via the bonding material", wherein the irradiation position of the light source is changed to be configured in a dome shape. A method for manufacturing a semiconductor device is characterized by having a process of "carrying a substrate into a mounting device", the mounting device having: a camera facing the solder or paste, i.e., a bonding material; and a lighting device having a light source disposed above the bonding material; a process of "applying the bonding material to the substrate"; a process of "changing the irradiation position of the light source, and inspecting the bonding material based on a plurality of images obtained by photographing the bonding material with the camera"; and a process of "bonding a die to the substrate via the bonding material".

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