JP2013079835A - Height measuring device for pointed bump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the height of a pointed bump of a semiconductor chip.SOLUTION: A surface illumination device 33 is disposed above a semiconductor wafer 21 on which a plurality of semiconductor chips including pointe bumps are formed, and the surface illumination device 33 illuminates the upper surface of the semiconductor wafer 21. A pair of imaging devices 34 and 35 are disposed obliquely above the semiconductor wafer 21 and capture images of the semiconductor chips including the pointed bumps on the semiconductor wafer 21 from the obliquely above position. A computer 36 detects the length of the pointed bump from the bottom to the tip end respectively on the basis of the pair of images captured by the pair of imaging devices 34 and 35, and calculates the height of the pointed bump using the detected pair of lengths and an angle formed between optical axes of the pair of imaging devices 34 and 35 and the upper face of the semiconductor waver 21.

Description

  The present invention relates to a tip bump height measuring device for measuring the height of a tip bump such as a stud bump, a conical bump, a triangular pyramid bump or the like used for connecting a semiconductor element to a printed circuit board.

  In recent years, with the reduction in size and weight of electronic devices, there has been a demand for downsizing of electronic components to be mounted. In order to meet this demand, surface-mounted electronic components without leads have been adopted instead of conventional electronic components with leads. Thus, in order to reduce the area occupied by electronic components, the progress in the field of semiconductor mounting in which semiconductor elements are directly mounted on a printed circuit board is remarkable. As a semiconductor mounting method for bonding the semiconductor element and the printed board, there is a flip chip mounting method in which the semiconductor electrode is bonded to the bottom surface. In this flip chip mounting method, stud bumps formed on semiconductor electrodes are used.

  First, the formation of the stud bump will be described. As shown in FIG. 13 as time elapses, a metal wire 2 having a diameter of about 25 μm made of gold is extruded from the through hole of the capillary 1 and the tip of the metal wire 2 is discharged. To form a spherical Au ball 3 by heating. Next, the Au ball 3 is pressure-bonded to the electrode 5 of the semiconductor element 4 and ultrasonic vibration is applied to diffuse and join the Au ball 3 on the surface of the electrode 5. The Au ball 3 is plastically deformed to form a pedestal portion 6a. Thereafter, the capillary 1 is separated from the pedestal 6a and the metal wire 2 is torn off to form the stud bump 6. In the stud bump 6, a pedestal portion 6a is formed at the lower portion, and a top portion 6b having a sharp tip due to the metal wire 2 is formed on the upper surface of the pedestal portion 6a.

  As shown in FIG. 14, the semiconductor element 4 having the stud bump 6 formed in this way has the stud bump 6 formed on the lower side and the top 6b of the stud bump 6 is placed on the transfer stand as shown in FIG. 7, the semiconductor element 4 is pulled up after being immersed in the conductive adhesive 8 provided on the substrate 7. At this time, the conductive adhesive 8 is transferred to the stud bump 6 by surface tension. Then, after positioning the semiconductor element 4 at a predetermined position on the printed circuit board 9, the semiconductor element 4 is pressure-bonded to the conductor land 10 at a predetermined position on the printed circuit board 9, and the entire printed circuit board 9 is heated to an appropriate temperature, The conductive adhesive 8 is cured. Thereby, the joining of the semiconductor element 4 and the printed circuit board 9 by the flip chip mounting method is completed.

  It is necessary to inspect whether or not the stud bump used for joining the semiconductor element to the printed board is properly formed on the semiconductor element. In this inspection, as shown in Patent Documents 1 to 3 below, using an imaging device, the stud bump is imaged from above the semiconductor element on which the stud bump is formed, and the pedestal portion and the top of the head portion of the stud bump are imaged. The stud bump is inspected by measuring the position, shape, and dimensions and determining whether the measured position, shape, and dimensions are within an allowable range.

JP-A-8-55854 JP-A-10-242219 JP 2005-166743 A

  However, none of the above prior art measures the height of the stud bump. Since the stud bump is usually made of gold, the surface forms a mirror surface. Therefore, the light incident on the surface of the stud bump is reflected in one direction without being scattered. Therefore, since there is a substantially flat portion on the upper surface of the pedestal portion of the stud bump, most of the light incident on the same portion from above is reflected upward, so that the pedestal portion of the stud bump can be imaged somehow. However, the top of the head of the stud bump is pointed, and the light incident on the top of the head does not scatter and reflects in various different directions depending on the incident position. I can't do it. For this reason, in the prior art, the height of the stud bump cannot be measured, and the inspection relating to the height of the stud bump cannot be performed. Further, as in the case of the stud bump, it was impossible to measure the height of the tip bump formed on the semiconductor element, such as a pointed conical bump or a triangular pyramid bump.

  The present inventor has discovered a solution principle capable of measuring the height of the tip bump in such a situation. Specifically, instead of taking an image of light reflected from the tip bump, the light reflected from the surface of the semiconductor element on which the tip bump is formed (that is, the electrode surface) is blocked by the tip bump. The shape of the pointed bump, particularly the shape of the top of the pointed bump, was successfully measured. Then, the height of the tip bump is measured using the measured shape of the tip bump.

  The present invention has been made to address the above-described conventional problems, and an object of the present invention is to provide a tip bump height measuring apparatus that measures the height of the tip bump using the solution principle. In addition, in the description of each constituent element of the present invention below, in order to facilitate understanding of the present invention, reference numerals of corresponding portions of the embodiment are described in parentheses, but each constituent element of the present invention is The present invention should not be construed as being limited to the configurations of the corresponding portions indicated by the reference numerals of the embodiments.

  In order to achieve the above object, the constitutional feature of the present invention is that light that radiates light on the upper surface of the semiconductor chip is disposed above the semiconductor chip (21a) having the tip bump (23) formed on the upper surface. Irradiation means (33), imaging means (34, 35) arranged obliquely above the semiconductor chip and imaging the semiconductor chip including the tip bumps from obliquely above, and tip bumps based on the image captured by the imaging means Height detecting means (36) for detecting the length from the bottom to the tip of the substrate and calculating the height of the tip bump using the detected length and the angle formed by the optical axis of the imaging means and the upper surface of the semiconductor chip. , S12 to S15).

  In the present invention configured as described above, when light is irradiated on the upper surface of the semiconductor chip by the light irradiating means, the reflected light from the upper surface of the semiconductor chip is scattered in all directions, and a part thereof is directed to the imaging means. Incident. On the other hand, the tip bump is generally formed of gold or the like, and since the surface is a mirror surface, the reflected light from the tip bump due to the light irradiated by the light irradiation means proceeds only in a specific direction, Almost no incident on the imaging means. In particular, since the top of the tip bump is sharp, the reflected light from the top of the tip bump does not enter the imaging means to the extent that it can be said. Accordingly, among the light reflected on the surface of the semiconductor chip excluding the tip bump, an image (that is, a shadow of the tip bump) as a result of being blocked by the tip bump is picked up by the image pickup means. As a result, the height detection means detects the length from the bottom to the tip of the tip bump based on the image picked up by the image pickup means, and the detected length and the optical axis of the image pickup means are the upper surface of the semiconductor chip. Since the height of the tip bump is calculated using the angle between the tip and the tip, the height of the tip bump is detected. Thereby, according to the present invention, the height of the tip bump can be measured with a relatively simple configuration, and the tip bump can be inspected including the height.

  Another feature of the present invention is that the first light irradiation means (33) is disposed above the semiconductor chip (21a) having the tip bump (23) formed on the upper surface, and irradiates the upper surface of the semiconductor chip. ), First and second imaging means (34, 35) that are disposed on both sides of the semiconductor chip diagonally above the semiconductor chip and respectively image the semiconductor chip including the tip bumps from diagonally above, and the first The lengths from the bottom to the tip of the tip bump are detected based on the first and second images picked up by the second image pickup means, and the detected first and second lengths, And height detecting means (36, S12 to S15) for calculating the height of the tip bump using the angle formed by the optical axis of the second imaging means and the upper surface of the semiconductor chip.

  According to this, the shape of the tip bumps on both sides in the direction connecting the first and second imaging means is captured as the first and second images by the first and second imaging means, respectively. Then, the height detection means detects first and second lengths from the bottom to the tip of the tip bump detected from the captured first and second images, respectively, and the detected first and second The height of the tip bump is calculated using the length of 2 and the angle formed by the optical axes of the first and second imaging means with the upper surface of the semiconductor chip. In this case, for example, if the height detection means performs processing such as averaging the two heights of the calculated tip bump, the top of the tip bump is inclined, and the first and second imaging means are moved. Even if one of the lengths from the bottom to the tip of the tip bump in the connecting direction has an error, this error is corrected and the height of the tip bump can be detected with high accuracy. Further, the height detecting means selects one of the two heights on the side away from the ideal height so that the height of the stud bump is strictly checked. Also good.

  Furthermore, in addition to the other features of the present invention, another feature of the present invention is a second light irradiation means (44) disposed above the semiconductor chip and irradiating light on the upper surface of the semiconductor chip, Third imaging means (43) disposed above the semiconductor chip and imaging the semiconductor chip including the tip bumps from directly above, and first and second images based on the third image captured by the third imaging means. Width detection means (45, S22 to S24) for detecting the width of the tip bump in the direction connecting the second image pickup means, and the tip bump detected by the height detection means using the width detected by the width detection means The height correction means (60, S31, S32) for correcting the height is provided.

  The two heights calculated by the height detection means based on the first and second images picked up by the first and second image pickup means are actually the first and second image pickup means. Is the length of the inclined portion from the bottom to the tip of the tip bump on both sides in the direction connecting the two. Therefore, if the width of the tip bumps on both sides in the direction connecting the first and second imaging means is small, the height of the tip bump calculated by the height detection means does not include a large error. However, if this width increases to some extent, a large error is included in the calculated height of the tip bump. According to another aspect of the present invention, the width detecting unit detects the width of the tip bump in the direction connecting the first and second imaging units, and the height correcting unit uses the width detected by the width detecting unit. Thus, the height of the tip bump detected by the height detecting means is corrected, so that the error is eliminated. As a result, according to the other feature of the present invention, the height of the tip bump can be detected with higher accuracy.

It is the whole bump height measuring device schematic diagram concerning one embodiment of the present invention. It is a block diagram which shows the specific example of the 1st measuring apparatus of FIG. It is a block diagram which shows the specific example of the 2nd measuring apparatus of FIG. It is a flowchart which shows the height measurement program run by the computer in a 1st measuring device. It is a flowchart which shows the width measurement program run by the computer in a 2nd measuring device. It is a flowchart which shows the height correction program performed by the integrated computer. (A) is a schematic diagram showing an example of a semiconductor wafer, and (B) is an explanatory diagram for explaining a moving direction of an XY stage on which the semiconductor wafer is placed. It is an image figure of one semiconductor chip in a semiconductor wafer. (A) is a figure which shows the picked-up image of the stud bump by a 1st measuring apparatus, (B) is a figure which shows the picked-up image of the stud bump after image-processing the picked-up image of (A). (A) (B) is explanatory drawing for demonstrating the relationship between the actual height of a stud bump, and the measurement height of the stud bump by a picked-up image. It is a figure which shows the picked-up image of the stud bump by a 2nd measuring apparatus. It is explanatory drawing for demonstrating the correction calculation of the height of a stud bump. It is explanatory drawing for demonstrating the formation method of a stud bump. It is explanatory drawing for demonstrating the connection method with respect to the printed circuit board of the semiconductor element in which the stud bump was formed.

  Hereinafter, a bump height measuring apparatus according to an embodiment of the present invention will be described. FIG. 1 is an overall schematic diagram of the bump height measuring apparatus. This bump height measuring device corrects the height of the measured stud bump, the data table 20 on which the semiconductor wafer as the measurement object is placed, the first measuring device 30 for measuring the height of the stud bump, and For this purpose, a second measuring device 40 for measuring the width of the stud bump, a transport device 50 for moving the semiconductor wafer, and a general computer 60 for controlling the entire operation of the bump height measuring device are provided.

  The document table 20 is a table for mounting a plurality of semiconductor wafers 21A before measurement and a plurality of semiconductor wafers 21B after measurement. The plurality of semiconductor wafers 21 </ b> A and 21 </ b> B are respectively placed at predetermined positions on the material table 20 in a predetermined direction. One semiconductor wafer 21 of the plurality of semiconductor wafers 21A and 21B is shown in FIG. The semiconductor wafer 21 is composed of a plurality of semiconductor chips 21a arranged in a matrix. One semiconductor chip 21a is representatively shown in FIG. A plurality of flat electrodes 22 are formed on the semiconductor chip 21a, and stud bumps 23 are formed on the plurality of electrodes 22, respectively. This stud bump 23 is as described in the background art section.

  As shown in FIG. 2, the first measuring apparatus 30 includes an XY stage 31 that places one semiconductor wafer 21 horizontally and moves the semiconductor wafer 21 in the X direction and the Y direction. The X direction and the Y direction are two directions orthogonal to each other in the horizontal direction. The XY stage 31 is driven in the X direction and the Y direction by a stage driver 32. A surface irradiation device 33 is disposed above the XY stage 31. The surface irradiation device 33 includes a plurality of LEDs arranged on the matrix, and a diffusion plate that is provided below the plurality of LEDs and diffuses light emitted by the LEDs in all directions. Irradiate the whole from all directions. The diffusion plate is made of, for example, a transparent acrylic plate.

  A pair of imaging devices 34 and 35 are arranged on the left and right sides of the surface irradiation device 33. More precisely, the pair of imaging devices 34 and 35 are positioned symmetrically with respect to the center of the surface irradiation device 33 in the movement direction (left-right direction in the drawing) of the XY stage 31 during imaging described later. The optical axes of the imaging devices 34 and 35 are in a direction inclined by a predetermined angle θ with respect to the horizontal plane, that is, the upper surface of the semiconductor wafer 21 (semiconductor chip 21a). The predetermined angle θ is an angle within a range of 30 degrees to 60 degrees, for example. These imaging devices 34 and 35 are composed of camera units 34a and 35a and lens units 34b and 35b, respectively. The camera units 34a and 35a include a line sensor in which a plurality of CCDs are arranged in a row, and a peripheral control circuit thereof. The line sensor extends in the direction perpendicular to the paper surface of FIG. 2, and its length is one side of one semiconductor chip 21a that has been photographed, and is orthogonal to the moving direction of the XY stage 31 at the time of imaging described later. It is equal to the length of one side in the direction (the length of one side in the vertical direction in FIG. 7A). The lens units 34b and 35b are composed of a plurality of lenses such as an objective lens and a relay lens, and form images of reflected light from the surface of the semiconductor wafer 21 on the line sensors of the camera units 34a and 35a.

  A computer 36 including a CPU, ROM, RAM, and other memories is connected to the stage driver 32 and the imaging devices 34 and 35. The computer 36 is controlled by the overall computer 60, and controls the stage driver 32 by controlling the movement of the XY stage 31 in the X and Y directions by executing the height measurement program shown in FIG. 7 (B)), image data from the camera units 34a and 35a of the imaging devices 34 and 35 are input while changing the imaging position of the semiconductor wafer 21 by the imaging devices 34 and 35, and based on the input image data. The height of the stud bump 23 is calculated.

  As shown in FIG. 3, the second measuring apparatus 40 includes an XY stage 41 that horizontally places one semiconductor wafer 21 and moves the semiconductor wafer 21 in the X direction and the Y direction. The XY stage 41 is driven in the X direction and the Y direction by a stage driver 42. An imaging device 43 is disposed above the XY stage 41. More precisely, the optical axis of the imaging device 43 is perpendicular to the upper surface of the semiconductor wafer 21 (semiconductor chip 21a). The imaging device 43 includes a camera unit 43a and a lens unit 43b. As in the case of the imaging devices 34 and 35 of the first measuring device 30, the camera unit 43a includes a line sensor in which a plurality of CCDs are arranged in one row and its peripheral control circuit. Also in this case, the line sensor extends in the direction perpendicular to the paper surface of FIG. 3, and its length is one side of one semiconductor chip 21a that has been photographed, and the movement of the XY stage 41 during imaging, which will be described later. It is equal to the length of one side (the length of one side in the vertical direction in FIG. 7A) perpendicular to the direction (left-right direction in the figure).

  The lens unit 43b includes an objective lens 43b1, a half mirror 43b2, a relay lens 43b3, and the like, and forms an image of reflected light from the surface of the semiconductor wafer 21 on each line sensor of the camera unit 43a. A coaxial irradiation device 44 is assembled to the lens portion 43b, and the light emitted from the coaxial irradiation device 44 is reflected by the half mirror 43b2 to illuminate the semiconductor wafer 21 vertically from above.

  A computer 45 including a CPU, a ROM, a RAM, and other memories is connected to the stage driver 42 and the imaging device 43. The computer 45 is controlled by the overall computer 60, and controls the stage driver 42 to control the movement of the XY stage 31 in the X and Y directions by executing the width measurement program shown in FIG. 5 (FIG. 7). (See (B)), while changing the imaging position of the semiconductor wafer 21 by the imaging device 43, image data from the camera unit 43a of the imaging device 43 is input, and the width of the stud bump 23 is calculated based on the input image data. To do.

  The transfer device 50 transfers one semiconductor wafer 21 of the plurality of semiconductor wafers 21A before measurement on the document table 20 onto the XY stage 31 of the first measurement device 30, and the transferred semiconductor wafer 21 is transferred to a predetermined level. It is placed in a predetermined position on the XY stage 31 in the direction. In addition, the transfer device 50 transfers one semiconductor wafer 21 after the height measurement on the XY stage 31 of the first measurement device 30 onto the XY stage 41 of the second measurement device 40, and the transferred semiconductor wafer 21. Is placed at a predetermined position on the XY stage 41 in a predetermined direction. Further, the transfer device 50 returns one semiconductor wafer 21 after the width measurement on the XY stage 41 of the second measurement device 40 into the plurality of semiconductor wafers 21 </ b> B of the material table 20.

  The transport of these semiconductor wafers 21 is controlled by the overall computer 60. In a steady state, after the semiconductor wafer 21 is measured by the first and second measuring devices 30 and 40, the semiconductor from the second measuring device 40 to the data table 20 is measured. The transfer of the wafer 21, the transfer of the semiconductor wafer 21 from the first measurement device 30 to the second measurement device 40, and the transfer of the semiconductor wafer 21 from the material table 20 to the first measurement device 30 are performed in this order. In the initial stage of measurement, only the transfer of the semiconductor wafer 21 from the material table 20 to the first measuring device 30 is performed, or from the first measuring device 30 and the material table 20 to the second measuring device 40 and the first measuring device. Only the transfer of each of the semiconductor wafers 21 to 30 is performed. At the end of the measurement, only the transfer of the semiconductor wafer 21 from the second measuring device 40 to the material table 20 is performed, or the material table 20 and the second measurement are performed from the second measuring device 40 and the first measuring device 30. Only the respective transport of the semiconductor wafer 21 to the apparatus 40 is performed.

  The general computer 60 also includes a CPU, ROM, RAM, and other memories, and sequentially controls the transfer of the semiconductor wafer 21 by the transfer device 50 by executing a program (not shown), and after the transfer of the semiconductor wafer 21, the first measuring device is controlled. 30 is instructed to measure the height of the stud bump 23, and after the semiconductor wafer 21 is conveyed, the second measuring device 40 is instructed to measure the width of the stud bump 23. Further, the overall computer 60 executes the height correction program shown in FIG. 6, and the height measurement result of the stud bump 23 by the first measurement device 30 is changed according to the width measurement result of the stud bump 23 by the second measurement device 40. To correct. The central computer 60 is also connected with an input device 61 such as a keyboard and a display device 62 having a liquid crystal display.

  Next, the operation of the embodiment configured as described above will be described. After the semiconductor wafer 21 is transferred, the first measuring device 30 measures the height of the stud bump 23 by executing a height measuring program, and the second measuring device 40 measures the width of the stud bump 23 by executing a width measuring program. Thereafter, the overall computer 60 corrects the height of the measured stud bump 23 using the width of the measured stud bump 23. Hereinafter, the height measurement of the stud bump 23, the width measurement of the stud bump 23, and the height correction of the stud bump 23 will be described in this order.

  First, the height measurement of the stud bump 23 will be described. The computer 36 starts execution of the height measurement program in step S10 of FIG. 4, moves the XY stage 31 in step S11, and pairs of the same semiconductor chip 21a from the pair of imaging devices 34 and 35. Each image data is acquired. The movement of the XY stage 31 will be described. The computer 36 controls the stage driver 32 to move the XY stage 31 in the X direction as shown in FIG.

  In this embodiment, the XY stage 31 is moved from left to right in the first movement, the XY stage 31 is moved from right to left in the second movement, and the XY stage 31 is reciprocated alternately left and right thereafter. Exercise. In this case, the line sensors of the camera units 34 a and 35 a are equal to the length of one side in the vertical direction of FIG. 7A of one semiconductor chip 21 a of the imaged semiconductor wafer 21. The amount of movement in the left-right direction is equal to the total length of the plurality of semiconductor chips 21 a arranged in a horizontal row of the semiconductor wafer 21. The XY stage 31 can be moved in this way because the configuration of the semiconductor wafer 21, that is, the arrangement of the semiconductor chips 21a on the semiconductor wafer 21, is known in advance, and the information representing the arrangement of the semiconductor chips 21a is shown in FIG. This is because the height measurement program is configured. As a result, by the first movement of the XY stage 31 from the left to the right in the process of step S11, image data by the line sensors of the plurality of semiconductor chips 21a in the uppermost stage in FIG. 7A is stored in the RAM. . Note that the amount of one-time movement of the XY stage 31 is set as appropriate depending on the capacity of the RAM and the like.

  After the processing in step S11, in step S12, the computer 36 selects the next one stud bump 23 (one electrode 22 portion on the semiconductor chip 21a including one stud bump 23) from the pair of image data. Each of the image data is extracted. This image data will be briefly described. The light irradiated on the upper surface of the semiconductor wafer 21 from the surface irradiation device 33 is diffused light diffused in all directions. The upper surfaces of the semiconductor chip 21a and the electrode 22 are not mirror surfaces, and the light from the surface irradiation device 33 is irregularly reflected in all directions. On the other hand, since the stud bump 23 is made of gold and its surface is a mirror surface, the light reflected on the surface of the stud bump 23 is reflected in a certain direction without irregular reflection, and most of the reflected light is imaged. Devices 34 and 35 are not reached. In particular, since the top 23b of the stud bump 23 is sharp, the reflected light from the top 23b does not enter the imaging devices 34 and 35. The optical axes of the imaging devices 34 and 35 are inclined by a predetermined angle θ with respect to the upper surface of the semiconductor chip 21a. Accordingly, the camera units 34 a and 35 a of the imaging devices 34 and 35 are images of light emitted from the surface irradiation device 33 and reflected on the upper surfaces of the semiconductor chip 21 a and the electrode 22 in the direction of the imaging devices 34 and 35. Thus, an image having a dark part (so-called shadow part) blocked by the stud bump 23 is formed.

  FIG. 9A shows an image representing the stud bump 23. A portion indicated by dots is a dark portion, and many portions of the pedestal portion 23a of the stud bump 23 are dark portions, and there are some bright portions. The top 23b of the stud bump 23 is a particularly dark part. This is because the pedestal portion 23a has a partly flat part, and part of the incident light from the surface irradiation device 33 reflected by the flat part is incident on the imaging devices 34 and 35. This is because the other parts of the pedestal 23a and the top 23b are steeply inclined, and most of the incident light from the surface irradiation device 33 reflected by the steeply inclined part does not enter the imaging devices 34 and 35. In FIG. 9A, a portion 23 a ′ below the pedestal 23 a of the stud bump 23 is a mapping due to the mirror effect of the upper surfaces of the semiconductor chip 21 a and the electrode 22.

  After the processing of step S12, the computer 36 processes the extracted pair of image data in step S13, and removes the portions 23a 'below the pedestal portion 23a of the stud bump 23 from the respective image data. . This is because the image based on the image data relating to the stud bump 23 is known in advance, and the portion 23a 'below the pedestal portion 23a can be easily deleted by image processing. FIG. 9B shows an image related to the stud bump 23 after the data processing.

After the processing in step S13, in step S14, the computer 36 determines the height (length from the bottom to the tip) Hy1 and Hy2 of the stud bump 23 in the stud bump image based on the processed pair of image data. Measure (see FIG. 9B). Next, in step S15, the computer 36 converts the measured heights Hy1 and Hy2 into the actual heights Hx1 and Hx2 of the stud bump 23 using the following equations 1 and 2.

  The equations 1 and 2 will be described. FIG. 10A schematically shows a state in which the stud bump 23 is imaged by the imaging devices 34 and 35. LEN indicates the lens function of the lens portions 34b and 35b of the imaging devices 34 and 35, and Hx (Hx1, Hx2) is the height of the stud bump 23 on the semiconductor chip 21a (electrode 22) (the actual stud bump 23). Height), and Hy (Hy1, Hy2) indicates the height of the stud bump 23 imaged by the camera units 34a and 35a by the lens function LEN. The actual height Hx (Hx1, Hx2) of the stud bump 23 is the vertical height of the stud bump 23 on the semiconductor chip 21a (electrode 22). In this case, since the optical axes of the camera units 34a and 35a (lens function LEN) are inclined by a predetermined angle θ with respect to the upper surfaces of the semiconductor chip 21a and the electrode 22, the actual height of the stud bump 23 is expressed by the above equation (1). , 2 are represented. Note that a is a magnification by the imaging devices 34 and 35, and since the arrangement of the XY stage 31 and the imaging devices 34 and 35 is determined in advance, the magnification a is a predetermined value.

As described above, the actual height Hx (Hx1, Hx2) of the stud bump 23 is the vertical height of the stud bump 23 on the semiconductor chip 21a (electrode 22). However, the stud bumps 23 imaged by the imaging devices 34 and 35 are actually measured because the external shape of the stud bumps 23 is an image obtained by blocking the light reflected from the upper surfaces of the semiconductor chip 21a and the electrode 22. The actual height Hx (Hx1, Hx2) of the stud bump 23 is the length of the inclined surface on the outer shape of the stud bump 23, as shown in FIG. When the length of the inclined surface is Hx, the following formula 3 is established.

When the portion of cos (θ−Δθ) of the denominator of Equation 3 is modified, it is expressed as Equation 4 below. Here, Δθ is substantially equal to half the angle of the tip of the top 23b of the stud bump 23, and considering that it is extremely small, cos Δθ is substantially “1” and sin Δθ is substantially “0”. Therefore, the above equation 3 is transformed into the following equation 5, and the length Hx (Hx1, Hx2) of the actual inclined surface of the stud bump 23 is also the height Hy of the stud bump 23 imaged by the camera units 34a, 35a. Using (Hy1, Hy2), it is expressed as Equations 1 and 2 above.

  After measuring the heights Hx1 and Hx2 (that is, the lengths Hx1 and Hx2 of the inclined portion) of the stud bump 23 from the left and right sides in steps S12 to S15, the computer 36 obtains the processing in step S11 in step S16. It is determined whether or not the measurement of the heights Hx1 and Hx2 of all the stud bumps 23 in the obtained image data has been completed. In this case, the left and right sides are directions along the moving direction of the XY stage 31. If the measurement of the heights Hx1 and Hx2 of all the stud bumps 23 in the image data has not been completed, the computer 36 makes a “No” determination at step S16, returns to step S12, and proceeds to steps S12 to S12 described above. The measurement of the heights Hx1 and Hx2 from the left and right sides of the stud bump 23 in S15 is repeated.

  When the measurement of the heights Hx1 and Hx2 of all the stud bumps 23 in the image data acquired by the process of step S11 is completed, the computer 36 determines “Yes” in step S16, and proceeds to step S17. Thus, it is determined whether or not the measurement of the heights Hx1 and Hx2 (that is, the lengths Hx1 and Hx2 of the inclined portion) from all the left and right sides of all the stud bumps 23 in the semiconductor wafer 21 is completed. If the measurement of the heights Hx1 and Hx2 of all the stud bumps 23 in the semiconductor wafer 21 has not been completed, the computer 36 determines “No” in step S17, returns to step S11, and returns to step S11. Then, the XY stage 31 is moved to acquire the next pair of image data related to the same plurality of semiconductor chips 21a from the pair of imaging devices 34 and 35, respectively. Then, the heights Hx1 and Hx2 of all the stud bumps 23 in the image data acquired by the process of step S11 are measured by the processes of steps S12 to S16. When the measurement of the heights Hx1 and Hx2 of all the stud bumps 23 in the image data is finished, the computer 36 again determines “Yes” in step S16, and all the stud bumps 23 in the semiconductor wafer 21 are determined. Until the measurement of the heights Hx1 and Hx2 is completed, the processes of steps S11 to S17 are repeated.

  When the measurement of the heights Hx1 and Hx2 of all the stud bumps 23 in the semiconductor wafer 21 is completed, the computer 36 determines “Yes” in step S17, and in step S18, The heights Hx1 and Hx2 of all the stud bumps 23 are output to the overall computer 60, and the execution of the height measurement program is terminated in step S19. In this case, in the output to the central computer 60 of the heights Hx1 and Hx2 of the stud bumps 23, information representing the semiconductor wafer 21 and the heights Hx1 and Hx2 of the stud bumps 23 are output in the order of measurement. The general computer 60 stores the information representing the output semiconductor wafer 21 and the heights Hx1 and Hx2 of the stud bumps 23 in the order of measurement. Also in this case, since the arrangement of the semiconductor chip 21a on the semiconductor wafer 21 and the arrangement of the stud bumps 23 on the semiconductor chip 21a is known in advance, the stud bumps 23 on the semiconductor wafer 21 can be specified. As a result, the heights Hx1 and Hx2 of all the stud bumps 23 of the semiconductor wafer 21 (that is, the lengths Hx1 and Hx2 of the inclined portions) are stored in the central computer 60 together with information for specifying the semiconductor wafer 21. Each time a new semiconductor wafer 21 is transferred to the XY stage 31 by the transfer device 50, the height of all the stud bumps 23 of different semiconductor wafers 21 is sequentially measured by executing this height measurement program. Will be.

  Next, the width measurement of the stud bump 23 will be described. The computer 45 starts execution of the width measurement program in step S20 of FIG. 5, moves the XY stage 31 in step S21, and acquires image data related to the plurality of semiconductor chips 21 a from the imaging device 43. The movement of the XY stage 31 in this case is the same as the process of step S11 of the height measurement program of FIG. 4 except that the computer 45 controls the stage driver 42.

  After the process of step S21, the computer 45, in step S22, selects the next one stud bump 23 (one electrode 22 portion on the semiconductor chip 21a including one stud bump 23) from the acquired image data. ) Image data is extracted. The image data in this case will be briefly described. In the second measuring device 40, the light irradiated on the upper surface of the semiconductor wafer 21 from the coaxial irradiation device 44 is reflected by the half mirror 43b2 and is directed upward (almost directly above) to the semiconductor chip 21a, the electrode 22 and the stud bump 23. It is the irradiated light. Also in this case, since the upper surfaces of the semiconductor chip 21a and the electrode 22 are not mirror surfaces, the light incident on the semiconductor chip 21a and the electrode 22 from the coaxial irradiation device 44 is irregularly reflected from the semiconductor chip 21a and the electrode 22 in all directions to capture an image. The light enters the device 43. On the other hand, since the stud bump 23 is made of gold and the surface thereof is a mirror surface, only the reflected light from the horizontal portion of the stud bump 23 is reflected upward to enter the imaging device 43, and other inclined portions. The reflected light from is not reflected upward and is not incident on the imaging device 43. Therefore, an image formed by the camera unit 43a of the imaging device 43 is as shown in FIG. In FIG. 11, a portion indicated by dots is a dark portion, and many portions of the pedestal portion 23 a of the stud bump 23 are dark portions, and there are some bright portions. The lower part of the pedestal 23a and the top 23b of the stud bump 23 are particularly dark parts.

After the process of step S22, the computer 45 measures the width Dy of the stud bump 23 in the stud bump image based on the extracted image data in step S23 (see FIG. 11). The direction of the width Dy in this case is the moving direction of the XY stage 41 and corresponds to the arrangement direction of the pair of imaging devices 34 and 35 of the first measuring device 30. In this case, since the image picked up by the image pickup device 43 is a plan view of the semiconductor chip 21a including the stud bump 23, the length corresponding to the diameter of the pedestal portion 23a of the stud bump 23 is measured as the width Dy. Next, in step S24, the computer 45 converts the measured width Dy into the actual width Dx of the stud bump 23 using Equation 6 below. Note that a in Expression 6 is the magnification of the imaging device 43.

  After the measurement of the width Dx of the stud bump 23 in steps S22 to S24, the computer 45 ends the measurement of the width Dx of all the stud bumps 23 in the image data acquired by the process of step S21 in step S25. It is determined whether or not. If the measurement of the width Dx of all the stud bumps 23 in the image data has not been completed, the computer 45 determines “No” in step S25, returns to step S22, and performs the studs in steps S22 to S24 described above. The measurement of the width Dx of the bump 23 is repeated.

  When the measurement of the width Dx of all the stud bumps 23 in the image data acquired by the process of step S21 is completed, the computer 45 determines “Yes” in step S25, and in step S26, the semiconductor wafer. It is determined whether or not the measurement of the width Dx of all the stud bumps 23 in 21 has been completed. If the measurement of the width Dx of all the stud bumps 23 in the semiconductor wafer 21 has not been completed, the computer 45 determines “No” in step S26, returns to step S21, and in step S21, returns to XY. The stage 31 is moved to acquire the next image data relating to the plurality of semiconductor chips 21a from the imaging device 43. Then, the widths Dx of all the stud bumps 23 in the image data acquired by the process of step S21 are measured by the processes of steps S22 to S25. When the measurement of the width Dx of all the stud bumps 23 in the image data is completed, the computer 45 again determines “Yes” in step S25, and the width Dx of all the stud bumps 23 in the semiconductor wafer 21. Steps S21 to S26 are repeatedly executed until the measurement is completed.

  When the measurement of the width Dx of all the stud bumps 23 in the semiconductor wafer 21 is completed, the computer 45 determines “Yes” in step S26, and in step S27, all the studs in the semiconductor wafer 21. The width Dx of the bump 23 is output to the overall computer 60, and the execution of the width measurement program is terminated in step S28. In this case, when outputting the width Dx of the stud bump 23 to the overall computer 60, information representing the semiconductor wafer 21 and the width Dx of the stud bump 23 are output in the order of measurement. The overall computer 60 stores the information representing the output semiconductor wafer 21 and the measurement order width Dx of the stud bump 23. Also in this case, since the arrangement of the semiconductor chip 21a on the semiconductor wafer 21 and the arrangement of the stud bumps 23 on the semiconductor chip 21a is known in advance, the stud bumps 23 on the semiconductor wafer 21 can be specified. Thereby, the width Dx of all the stud bumps 23 of the semiconductor wafer 21 is stored in the central computer 60 together with the information for specifying the semiconductor wafer 21. Each time a new semiconductor wafer 21 is transferred to the XY stage 41 by the transfer device 50, the width of all the stud bumps 23 of different semiconductor wafers 21 is sequentially measured by executing this width measurement program. become.

  Next, height correction of the stud bump 23 will be described. The central computer 60 starts execution of the height correction program in step S30 of FIG. 6, and reads the heights Hx1, Hx2 and width Dx related to the next stud bump 23 in step S31. In this case, during execution of the height measurement program of FIG. 4 and the width measurement program of FIG. 5 described above, the central computer 60 sends information representing the semiconductor wafer 21 and all the studs of the semiconductor wafer 21 represented by the information. The height Hx1, Hx2 and width Dx of the bump 23 are stored. Therefore, in reading the heights Hx1, Hx2 and the width Dx regarding the next stud bump 23, the heights Hx1, Hx2 and the width Dx regarding the same stud bump 23 of the same semiconductor wafer 21 can be read sequentially.

After the process of step S31, the overall computer 60 calculates the corrected height H of the stud bump 23 by executing the following equation 7 using the read heights Hx1, Hx2 and width Dx in step S32. calculate.

  The correction calculation of the height H will be described. The heights Hx1 and Hx2 related to the stud bump 23 are inclined on the left and right sides (movement directions of the XY stages 31 and 41) of the stud bump 23 as shown in FIG. The length of the part. The width Dx of the stud bump 23 is the length in the left-right direction (the moving direction of the XY stages 31 and 41) of the pedestal portion 23a of the stud bump 23. Therefore, the actual height H of the stud bump 23, that is, the corrected height H is calculated by the calculation of Equation 7.

  After calculating the corrected height H, the central computer 60, in step S33, the absolute value of the difference H−Href between the corrected height H and the ideal height Href of the stud bump 23 determined in advance | H−Href | is calculated, and it is determined whether or not the absolute value | H−Href | is within a predetermined allowable value. If the absolute value | H−Href | is within the allowable value, the overall computer 60 determines “Yes” in step S33, and sets the error flag ERR to “0” in step S34. On the other hand, if the absolute value | H−Href | is not within the allowable value, the overall computer 60 determines “No” in step S33, and sets the error flag ERR to “1” in step S35. After the processing of these steps S34 and S35, the central computer 60 uses the calculated correction height H and the value of the error flag ERR, which is the determination result, the information indicating the semiconductor wafer 21 and the stud bump 23 in step S36. The information to be specified is stored in the memory device.

  Then, after the processing of step S36, the overall computer 60 determines whether or not the correction and determination regarding the height H of all the stud bumps 23 in the semiconductor wafer 21 have been completed. If the correction and determination regarding the height H of all the stud bumps 23 have not been completed, the overall computer 60 determines “No” in step S37, returns to step S31, and includes the above-described steps S31 to S36. The correction and determination processing regarding the height H of the stud bump 23 is repeated. As a result, when the correction and determination regarding the height H of all the stud bumps 23 in one semiconductor wafer 21 are completed, the overall computer 60 determines “Yes” in step S37, and this height is determined in step S38. Finishes the correction program. The height correction and determination of the stud bumps 23 of different semiconductor wafers 21 can be sequentially performed by sequentially executing the height correction program.

  According to the embodiment, when the upper surface of the semiconductor wafer 21 is irradiated by the surface irradiation device 33, the reflected light from the upper surfaces of the plurality of semiconductor chips 21a (electrodes 22) of the semiconductor wafer 21 is scattered in all directions, A part of the light enters the imaging devices 34 and 35. On the other hand, since the surface of the stud bump 23 is a mirror surface, the reflected light from the stud bump 23 due to the light irradiated by the surface irradiation device 33 proceeds only in a specific direction and hardly enters the imaging devices 34 and 35. . In particular, since the top 23b of the stud bump 23 is sharp, the reflected light from the top 23b of the stud bump 23 does not enter the imaging devices 34 and 35 to the extent that it can be said. Therefore, among the light reflected on the surface of the semiconductor chip 21a (electrode 22) excluding the stud bump 23, an image (that is, corresponding to the shadow of the tip bump) as a result of being blocked by the stud bump 23 is obtained by the imaging device 34, 35, the image is captured.

  Then, the computer 36 executes the height measurement program to detect the lengths Hy1 and Hy2 from the bottom to the tip of the stud bump 23 based on the images picked up by the image pickup devices 34 and 35. The stud bumps 23 are obtained by performing the calculations of the above formulas 1 and 2 using the lengths Hy1 and Hy2 and the angle θ between the optical axes of the imaging devices 34 and 35 and the upper surface of the semiconductor wafer 21 (semiconductor chip 21a and electrode 22). Since the heights Hx1 and Hx2 are calculated, the heights Hx1 and Hx2 of the stud bumps 23 are detected. Thereby, according to the said embodiment, the height of the stud bump 23 can be measured with a comparatively simple structure, and the inspection of the stud bump 23 can be performed including the height.

  In the above embodiment, the semiconductor wafer 21 (semiconductor chip 21 a) is irradiated from above by the coaxial irradiation device 44, and the imaging device 43 images the upper surface of the semiconductor chip 21 a including the stud bumps 23. Then, the computer 45 detects the width Dx of the stud bump 23 in the direction connecting the imaging devices 34 and 35 based on the image captured by the imaging device 43 by executing the width measurement program. Further, the heights Hx1 and Hx2 and the width Dx of the stud bump 23 are output from the computers 36 and 45 to the general computer 60, respectively. Then, the overall computer 60 executes the height correction program and corrects the heights Hx1 and Hx2 by the correction calculation using the width Dx of Equation 7 above. As a result, even if the widths of the stud bumps 23 on both sides in the direction connecting the imaging devices 34 and 35 are somewhat large, the errors of the heights Hx1 and Hx2 can be reduced, and the height H of the stud bumps 23 can be made more accurate. Can be detected.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the object of the present invention.

  In the above embodiment, the image sensors of the camera units 34a, 35a, 43a of the imaging devices 34, 35, 43 are configured by line sensors in which a plurality of CCDs are arranged in one row. However, instead of this line sensor, an area sensor in which a plurality of CCDs are arranged in a matrix may be used. In this case, in the movement of the XY stages 31 and 41 in the step S11 of the height measurement program in FIG. 4 and the step S21 in the width measurement program in FIG. 5, the image is taken every time the portion of the semiconductor chip 21a is imaged on the area sensor. The XY stages 31 and 41 may be moved by a length corresponding to the length of the part.

  In the above embodiment, the first measuring device 30 measures the heights Hx1 and Hx2 of the stud bump 23, the second measuring device 40 measures the width Dx of the stud bump 23, and the overall computer 60 uses the width Dx. The heights Hx1 and Hx2 are corrected by using and the height H of the stud bump 23 is detected. However, instead of this, the measurement of the width Dx of the stud bump 23 by the second measuring device 40 is omitted, and the correction of the heights Hx1 and Hx2 by the overall computer 60 is omitted, and the measurement is performed by the first measuring device 30. The average value (Hx1 + Hx2) / 2 of the heights Hx1 and Hx2 of the stud bumps 23 may be calculated as the height H of the stud bumps 23. According to this, the error in the height H of the stud bump 23 having a large width Dx is increased to some extent, but if the width Dx is not so large, the error is not so large, and this error can be allowed in the inspection of the stud bump 23. In some cases. Also, one of the two heights Hx1 and Hx2 of the stud bump 23 on the side away from the ideal height is selected so that the height of the stud bump 23 is strictly inspected. May be.

  Furthermore, the measurement of the two heights Hx1 and Hx2 of the stud bump 23 by the first measuring device 30 can be made to measure only one height. In this case, one of the pair of imaging devices 34 and 35 in the first measuring device 30 is omitted, and the height Hy1 (or Hy2) of the stud bump 23 is measured by one imaging device, and the height measurement program of the computer 36 is measured. The measured height Hy1 (or Hy2) may be converted into the actual height Hx1 (or Hx2) of the stud bump 23 by executing the above. Even in this case, an error occurs as described above, but if the shape of the stud bump 23 is substantially symmetrical in the moving direction of the XY stage 21, the height of the stud bump 23 is the same as when the correction by the width Dx is omitted. H may be obtained, and the error may be allowed in the inspection of the stud bump 23 in some cases.

  Moreover, in the said embodiment, the height measuring apparatus which measures the height of the stud bump 23 was demonstrated. However, the height of a conical bump, a triangular pyramid bump, or the like formed by spraying gold particles can be measured using the height measuring device of the above embodiment. That is, the thin tip bumps including the stud bump, conical bump and triangular pyramid bump are common in that the surface of gold or the like is usually a mirror surface and has a thin tip portion, and using this common point, The height of the tip bumps such as stud bumps, conical bumps, and triangular pyramid bumps can be measured.

20 ... Data table 21, 21A, 21B ... Semiconductor wafer, 21a ... Semiconductor chip, 22 ... Electrode, 23 ... Stud bump, 30 ... First measuring device, 31 ... XY stage, 33 ... Surface irradiation device, 34, 35 ... Imaging device 34a, 35a ... Camera unit, 34b, 35b ... Lens unit, 36 ... Computer, 40 ... Measuring device, 41 ... XY stage, 43 ... Imaging device, 43a ... Camera unit, 43b ... Lens unit, 44 ... Coaxial irradiation Device 45 ... Computer 50 ... Conveying device 60 ... General computer

Claims (3)

A light irradiation means for irradiating light on the upper surface of the semiconductor chip, disposed above the semiconductor chip having a tip bump formed on the upper surface;
An imaging means that is disposed obliquely above the semiconductor chip and images the semiconductor chip including the tip bump from obliquely above;
The length from the bottom to the tip of the tip bump is detected based on the image picked up by the image pickup means, and the detected length and the angle formed by the optical axis of the image pickup means and the upper surface of the semiconductor chip are determined. A tip bump height measuring apparatus, comprising: a height detecting means for calculating the height of the tip bump. A first light irradiating means for irradiating light on the upper surface of the semiconductor chip, the tip bump being disposed above the semiconductor chip formed on the upper surface;
First and second imaging means disposed on both sides obliquely above the semiconductor chip across the semiconductor chip and imaging the semiconductor chip including the tip bump from obliquely above;
Based on the first and second images picked up by the first and second image pickup means, the lengths from the bottom to the tip of the tip bump are detected, respectively, and the detected first and second lengths are detected. And a height detecting means for calculating a height of the tip bump using an angle formed by an optical axis of the first and second imaging means and an upper surface of the semiconductor chip. Bump height measuring device. In the height measuring device of the tip bump according to claim 2, further,
A second light irradiation means disposed above the semiconductor chip for irradiating light on the upper surface of the semiconductor chip;
A third imaging unit disposed above the semiconductor chip and imaging the semiconductor chip including the tip bump from directly above;
Width detecting means for detecting a width of the tip bump in a direction connecting the first and second imaging means based on a third image imaged by the third imaging means;
A tip bump height measuring device, comprising: a height correcting unit that corrects the height of the tip bump detected by the height detecting unit using the width detected by the width detecting unit. .

Images