JP2005233780A - Height measuring method and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure height information on an object to be inspected formed on a substrate and covered with a covering material, and to control a gap between the substrate and the covering material at a proper value on the basis of the height information of the object to be inspected. <P>SOLUTION: A stripe patterned light P having a wavelength in an infrared region to be transmitted through a semiconductor chip 3 mainly made of silicon is projected onto the substrate 5 on which the semiconductor chips 3 is mounted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a height measuring method and apparatus for measuring a three-dimensional shape of an inspection object such as a solder bump formed on a flip chip mounting substrate, for example.

  In recent years, in the field of electronic devices, products are required to be reduced in size, thickness, and weight. Similar requirements are increasing for packages that make up electronic devices. In view of such circumstances, flip chip mounting is being widely adopted instead of packages using electrode leads. In this flip chip mounting, solder bumps are formed on the electrode pads of the semiconductor chip, and the semiconductor chip is directly mounted on a circuit board (hereinafter abbreviated as a substrate) via the solder bumps.

  In general, in flip-chip mounting, a solder bump is formed on a semiconductor chip or a solder bump is formed on a substrate, and then the semiconductor chip and the substrate are arranged to face each other via the solder bump and heated. The semiconductor chip is mounted on the substrate by melting the pump. In addition, a sealing agent is injected between the semiconductor chip and the substrate in order to ensure insulation between bonding points by solder bumps between the semiconductor chip and the substrate and to ensure bonding strength. In order to inject the sealing agent, it is necessary to secure a certain gap between the semiconductor chip and the substrate. When this gap is narrowed, the melted solder spreads and the adjacent solder bumps come into contact with each other to cause a short circuit, or the sealant does not sufficiently enter between the semiconductor chip and the substrate, so that the bonding strength cannot be ensured. When the gap between the semiconductor chip and the substrate widens, bump connection failure occurs.

As a technique for solving such a problem, there is, for example, Patent Document 1. In this patent document 1, before mounting a semiconductor chip on a substrate, a hard member or a resin layer is disposed between the semiconductor chip and the substrate to secure a gap between the semiconductor chip and the substrate, A mounting apparatus having a method for measuring in advance the height of solder bumps formed on a chip is described.
JP 2000-299330 A

  However, Patent Document 1 is for securing a gap between a semiconductor chip and a substrate or measuring the height of a solder bump before mounting the semiconductor chip on the substrate. The semiconductor chip is mounted on the substrate. The gap between the semiconductor chip and the substrate is not measured later. For this reason, it cannot be confirmed whether the gap between the semiconductor chip and the substrate can be maintained at an appropriate value after the semiconductor chip is mounted on the substrate.

  The present invention projects a predetermined pattern light having a wavelength that is transmitted through the coating onto the inspection object formed on the substrate and covered with the coating, and the predetermined pattern light transmitted through the coating is projected onto the inspection object. Is a height measurement method for acquiring a plurality of phase shift image data from scattered light from an object to be inspected and acquiring height information of the object to be inspected based on the plurality of phase shift image data. .

  The present invention relates to a projection optical system for projecting a predetermined pattern light having a wavelength that transmits a coating to an inspection object formed on the substrate and covered with the coating, and a predetermined pattern light transmitted through the coating. A scanning mechanism that shifts the phase on the inspection object, an imaging optical system that forms an image of scattered light from the inspection object, an image sensor that picks up an image of the inspection object imaged by the imaging optical system, A height measurement apparatus comprising a height information calculation unit that acquires height information of an object to be inspected based on a plurality of phase shift image data acquired by imaging of an imaging device when phase shifting is performed by a scanning mechanism. is there.

  The present invention can provide a height measuring method and apparatus capable of measuring height information of an object to be inspected formed on a substrate and covered with a coating.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a height measuring apparatus employing a pattern projection method. A projection optical system 2 is provided obliquely above the observation object 1. The observation object 1 is flip-chip mounted. For example, as shown in FIG. 2, a spherical solder bump 4 is formed on a semiconductor chip 3 made of silicon, or a substrate 5 on which a circuit pattern is formed. A spherical solder bump 4 is formed, and thereafter, the semiconductor chip 3 and the substrate 5 are arranged to face each other via the solder bump 4 and heated, and the solder bump 4 is melted to mount the semiconductor chip 3 on the substrate 5. Is.

  The projection optical system 2 shifts the fringe pattern light P in the infrared region having light and darkness at equal intervals with respect to the substrate 5 on which the semiconductor chip 3 is mounted via the solder bumps 4 by a predetermined phase. And project. The projection optical system 2 projects the fringe pattern light P onto the substrate 5 at a projection angle α.

  Specifically, the projection optical system 2 includes a light source 6, a filter 7, an illumination optical system 8, a scanning mechanism 9 having a pattern plate 9a, and a projection lens system 10. Of these, the filter 7, the illumination optical system 8, the scanning mechanism 9 having the pattern plate 9 a, and the projection lens system 10 are provided on the optical path of the light emitted from the light source 6.

  The light source 6 emits light including a wavelength in the infrared region, and the filter 7 cuts light having a wavelength other than the infrared region included in the light emitted from the light source 6. As a light source that emits light including wavelengths in the infrared region, for example, a laser light source can be used. However, if the light source is a laser light source, only a specific wavelength, that is, a wavelength in the infrared region is emitted. Therefore, a filter that cuts light having a wavelength other than the above-described infrared region is not necessary.

  The illumination optical system 8 equalizes the intensity of light in the infrared region that has passed through the filter 7. The scanning mechanism 9 includes a pattern plate 9a formed with a plurality of slits that are parallel to each other and equally spaced. This pattern plate 9a shapes the light in the infrared region whose light intensity is made uniform by the illumination optical system 8 into the striped pattern light P having the wavelength in the infrared region having light and darkness at equal intervals. The scanning mechanism 9 moves the pattern plate 9 a in the direction S perpendicular to the optical path direction of the stripe pattern light P, thereby shifting the phase of the stripe pattern light P on the substrate 5 and the solder bumps 4. For each phase shift amount, for example, 0 [rad], π / 2 [rad], π [rad], and 3π / 2 [rad]. The projection lens system 10 projects the fringe pattern light P phase-shifted by the scanning mechanism 9 onto the substrate 5 and the solder bumps 4.

  An imaging optical system 11 and an image sensor 12 are provided above the substrate 5 (observation object 1), specifically, on the normal line of the substrate 5. The imaging optical system 11 images the scattered light Q from the substrate 5 and the solder bumps 4 on the light receiving surface of the image sensor 12. The scattered light Q is light scattered in various directions on the surface of the inspection object 1. The image sensor 12 captures an image formed on the light receiving surface, that is, an image of the stripe pattern light P projected on the substrate 5 and the solder bump 4 and outputs the image signal. The imaging element 12 is formed by, for example, arranging a plurality of CCD elements on a two-dimensional plane.

  The computer (height information calculation unit) 13 uses the scanning mechanism 9 to generate an image of the stripe pattern light P at each phase amount of 0 [rad], π / 2 [rad], π [rad], 3π / 2 [rad], for example. Each time the phase shift is performed, an image signal output from the image sensor 12 is captured to obtain a plurality of phase shift image data, and height information of the solder bumps 4 is obtained based on the phase shift image data.

  Specifically, the computer 13 includes a memory unit 14, a calculation processing unit 15 that calculates the height information of the solder bumps 4, a comparison calculation unit 16 that compares various data, and a light adjustment instruction that gives a light control instruction to the light source 6. A light instruction unit 17. A display device 18 is connected to the computer 13. The memory unit 14 stores a plurality of phase shift image data for each phase amount 0 [rad], π / 2 [rad], π [rad], and 3π / 2 [rad].

  The arithmetic processing unit 15 performs arithmetic processing on the plurality of phase shift image data stored in the memory unit 14 to obtain the height information of the solder bumps 4. That is, the computer 13 captures the image signal output from the image sensor 12 and stores it as a plurality of phase shift image data corresponding to each phase shift amount of the fringe pattern light P. The arithmetic processing unit 15 of the computer 13 obtains pixel luminance information at an arbitrary position (x, y) in the plurality of phase shift image data. In general, the relationship between the luminance value Ii and the phase φ (x, y) is expressed by the following equation.

Ii (x, y) = a (x, y) + b (x, y) .cos {φ (x, y) + δi} (1)
However, a (x, y) is a luminance offset component, b (x, y) is a contrast component, and δi is an i-th phase shift amount. If each luminance value Ii (x, y) is obtained by changing the phase shift amount δi three times or more by the above equation (1), the luminance offset component a (x, y) and the contrast component b, which are unknown amounts, are obtained. (x, y) and phase φ (x, y) can be obtained. With this phase φ (x, y), height information h (x, y) at an arbitrary position (x, y) is
h (x, y) = (p / sin α) · {φ (x, y) + 2nπ} / 2π (2)
Is required. Here, p is the pitch of the stripe pattern light P, α is the projection angle of the stripe pattern light P, and n is the order. Therefore, the arithmetic processing unit 15 calculates the phase φ (x, y) by calculating the above equation (1), and then calculates the height at the position of each pixel (x, y) by calculating the above equation (2). Information h (x, y) is calculated. The computer 13 displays the height information h (x, y) of the solder bump 4 calculated by the arithmetic processing unit 15 on the display device 18.

  Next, the operation of the apparatus configured as described above will be described.

  When light is emitted from the light source 6, light having a wavelength other than the infrared region is cut by passing through the filter 7. The light in the infrared region that has passed through the filter 7 is made uniform by the illumination optical system 8 and enters the scanning mechanism 9.

  The light in the infrared region incident on the scanning mechanism 9 is shaped by the pattern plate 9a into the fringe pattern light P having the wavelength in the infrared region having light and darkness at equal intervals. In addition, the scanning mechanism 9 moves the pattern plate 9a in the direction S perpendicular to the optical path direction of the stripe pattern light P, whereby the stripe pattern light P is, for example, 0 [rad], π / 2 [rad], π The phase is shifted every phase shift amount of [rad] and 3π / 2 [rad].

  The phase-shifted fringe pattern light P is projected onto the substrate 5 and the solder bumps 4 by the projection lens system 10 as shown in FIG. Here, since the semiconductor chip 3 is mainly formed of silicon, the fringe pattern light P having a wavelength in the infrared region passes through the semiconductor chip 3 and reaches the surfaces of the solder bumps 4 and the substrate 5.

  At this time, since the solder bumps 4 are formed as spherical bodies on the surface of the substrate 5, the fringe pattern light P is projected into the spherical solder as shown in FIG. It deforms along the surface shape of the bump 4. The fringe pattern light P is phase-shifted for each phase shift amount of, for example, 0 [rad], π / 2 [rad], π [rad], and 3π / 2 [rad]. The amount of deformation of the stripe pattern light P projected onto the solder bump 4 changes. Since the solder bumps 4 are made of metal, the projected stripe pattern light P is scattered by the solder bumps 4. Further, since the circuit pattern or the like made of a metal material is formed on the surface of the substrate 5, the projected stripe pattern light P is scattered on the surface of the substrate 5.

  The scattered light Q from the solder bumps 4 and the substrate 5 is imaged on the imaging surface of the imaging element 12 by the imaging optical system 11. The image pickup device 12 sequentially forms solder bumps 4 each time the fringe pattern light P is phase-shifted, for example, every phase shift amount 0 [rad], π / 2 [rad], π [rad], 3π / 2 [rad]. And the scattered light Q from the board | substrate 5 is imaged and the image signal is output.

  The computer 13 takes in the image signal output from the image sensor 12 and each phase shift amount (0 [rad], π / 2 [rad], π [rad], 3π / 2 [rad] of the fringe pattern light P) ) Is stored in the memory unit 14.

  Next, the arithmetic processing unit 15 of the computer 13 reads out each phase shift image data stored in the memory unit 14, and calculates the phase φ (x, y) at an arbitrary position (x, y) in the phase shift image data as described above. The formula (1) is calculated and obtained, and then the pixel height information h (x, y) at the arbitrary position (x, y) is calculated by calculating the formula (2).

  Next, the arithmetic processing unit 15 calculates each phase φ (x, y) for all the pixels, and when the phase φ (x, y) is calculated for all the pixels, each phase φ ( x, y) are combined and phase-connected, and converted into height information h (x, y) of the entire substrate 5 and solder bump 4. The height information h (x, y) continuously represents the surface shapes of the substrate 5 and the solder bump 4 in three dimensions. The arithmetic processing unit 15 extracts the height information h (x, y) of the solder bump 4 from the overall height information h (x, y) of the substrate 5 and the solder bump 4 and displays it on the display device 18. Since the height information h (x, y) of the solder bump 4 is equal to the gap between the substrate 5 and the semiconductor chip 3, the height information h (x, y) is used as the gap between the substrate 5 and the semiconductor chip 3. Display as.

  If the gap between the substrate 5 and the semiconductor chip 3 is not an appropriate value, the molten solder spreads and the adjacent solder bumps 4 come into contact with each other to cause a short circuit, or there is a sealant between the semiconductor chip 3 and the substrate 5. If it does not enter sufficiently, the bonding strength will not be ensured. Further, when the gap between the semiconductor chip 3 and the substrate 5 is widened, the connection of the solder bumps 4 becomes poor. When the gap between the semiconductor chip 3 and the substrate 5 is wide, when the gap between the semiconductor chip 3 and the substrate 5 is readjusted with respect to the flip chip mounting machine or when the solder bumps 4 are heated and melted. The heating temperature can be readjusted.

  Thereafter, in the readjusted flip chip mounting machine, the solder bumps 4 are formed on the semiconductor chip 3 or the solder bumps 4 are formed on the substrate 5, and then the semiconductor chip 3 and the substrate 5 are soldered. When the semiconductor chip 3 is mounted on the substrate 5 by disposing and heating through the bump 4 and melting the solder bump 4, the gap between the substrate 5 and the semiconductor chip 3 becomes an appropriate value.

  As described above, according to the first embodiment, the fringe pattern light P having a wavelength in the infrared region that transmits the semiconductor chip 3 mainly made of silicon is projected onto the substrate 5 on which the semiconductor chip 3 is mounted. The stripe pattern light P can pass through the semiconductor chip 3 and reach the surface of the solder bump 4 and the substrate 5, and a plurality of phase shift image data acquired by imaging the scattered light Q from the solder bump 4 and the substrate 5. Thus, the height information of the solder bump 4, that is, the gap between the substrate 5 and the semiconductor chip 3 can be calculated.

  Therefore, after mounting the semiconductor chip 3 on the substrate 5, the gap between the semiconductor chip 3 and the substrate 5 can be measured to confirm whether the gap between the semiconductor chip 3 and the substrate 5 can be maintained at an appropriate value. If the gap between the substrate 5 and the semiconductor chip 3 is not an appropriate value, feedback to the flip chip mounting machine to readjust the gap between the semiconductor chip 3 and the substrate 5 or heat the solder bump 4 to melt The gap between the substrate 5 and the semiconductor chip 3 can be corrected to an appropriate value by readjusting the heating temperature.

  Next, a second embodiment of the present invention will be described with reference to the drawings. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 4 is a configuration diagram of a height measuring apparatus employing the pattern projection method. A base 20 erected in a direction perpendicular to the surface of the substrate 5 (observation object 1) (the height direction of the substrate 5 and the Z-axis direction) includes a height direction moving mechanism 21 and a movement amount measuring device 22. Is provided.

  The height direction moving mechanism 21 raises and lowers the imaging optical system 11 in the height direction of the substrate 5 (observation object 1) in response to a height direction drive command from the Z-axis control unit 23 of the computer 13. The height direction moving mechanism 21 includes a Z-axis motor 24 that drives in the height direction of the substrate 5, and a connecting member 25 that connects the Z-axis motor 24 and the imaging optical system 11. The height direction moving mechanism 21 moves the imaging optical system 11 in the height direction of the solder bump 4 when the height of the solder bump 4 is equal to or greater than the depth of focus of the imaging optical system 11. This is suitable for obtaining height information h (x, y).

  The movement amount measuring device 22 measures the movement amount in the height direction of the imaging optical system 11 that moves up and down in the height direction of the substrate 5 by the height direction moving mechanism 21, and sends this movement amount measurement signal to the computer 13. . This movement amount measuring device 22 uses, for example, a linear scale. In this movement amount measuring device (linear scale) 22, for example, a sensor 27 slides on a scale plate 26 provided in the height direction. This sensor 27 moves on the scale plate 26 in the height direction in conjunction with the movement of the imaging optical system 11 in the height direction, and outputs a movement amount signal corresponding to the movement amount in the height direction.

  The Z-axis control unit 23 of the computer 13 issues a height direction drive command to the height direction moving mechanism 21 and receives a movement amount signal output from the movement amount measuring device 22 to receive the movement amount signal of the imaging optical system 11. The amount of movement in the height direction is read, and the amount of movement in the height direction is passed to the arithmetic processing unit 15.

  The arithmetic processing unit 15 includes the height information h (x, y) of the solder bump 4 acquired based on the plurality of phase shift image data stored in the memory unit 14, that is, the gap between the substrate 5 and the semiconductor chip 3, The original height information h (x, y) of the solder bump 4 is obtained from the movement amount of the imaging optical system 11 measured by the movement amount measuring device 22.

  Next, the operation of the apparatus configured as described above will be described.

  When the height of the solder bump 4 is equal to or greater than the depth of focus of the imaging optical system 11, the Z-axis control unit 23 issues a height direction drive command to the height direction moving mechanism 21. Accordingly, the height direction moving mechanism 21 moves the imaging optical system 11 in the height direction of the solder bump 4. At the same time, the movement amount measuring device 22 measures the movement amount in the height direction of the imaging optical system 11 that moves up and down in the height direction of the substrate 5 by the height direction moving mechanism 21, and sends this movement amount measurement signal to the computer 13. Send it out. The Z-axis control unit 23 of the computer 13 receives the movement amount measurement signal output from the movement amount measuring device 22, reads the movement amount in the height direction of the imaging optical system 11, and calculates the movement amount in the height direction. It passes to the arithmetic processing unit 15.

  On the other hand, as described above, the fringe pattern light P having a wavelength in the infrared region is phase-shifted, for example, every phase shift amount 0 [rad], π / 2 [rad], π [rad], 3π / 2 [rad]. A plurality of pieces of phase shift image data are acquired, and height information of the solder bumps 4, that is, a gap between the substrate 5 and the semiconductor chip 3 is calculated from these phase shift image data.

  The arithmetic processing unit 15 determines the original height information h (x, y) of the solder bump 4 based on the gap between the substrate 5 and the semiconductor chip 3 and the movement amount of the imaging optical system 11 measured by the movement amount measuring device 22. )

  As described above, according to the second embodiment, the height direction moving mechanism 21 that moves the imaging optical system 11 up and down in the height direction of the substrate 5 and the amount of movement of the imaging optical system 11 in the height direction are set. Since it has the moving amount measuring device 22 to measure, it goes without saying that the same effect as the first embodiment is obtained, and even if the height of the solder bump 4 is greater than the depth of focus of the imaging optical system 11. The height information of the solder bump 4, that is, the gap between the substrate 5 and the semiconductor chip 3 can be calculated.

  Next, a third embodiment of the present invention will be described with reference to the drawings. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

FIG. 5 is a configuration diagram of a height measuring apparatus employing the pattern projection method. For example, two projection optical systems 2 and 30 are provided as a plurality of projection optical systems. The projection optical systems 2 and 30 have the same projection angle α with respect to the substrate 5 and project the respective fringe pattern lights P ₁ and P ₂ having wavelengths in the infrared region onto the substrate 5. Is different. The projection optical system 2 is a first projection optical system, and the projection optical system 30 is a second projection optical system.

  The second projection optical system 30 includes a light source 31, a filter 32, an illumination optical system 33, a scanning mechanism 34 having a pattern plate 34a, and a projection lens system 35. The filter 32, the illumination optical system 33, the scanning mechanism 34, and the projection lens system 35 are provided on the optical path of the light emitted from the light source 31.

  The light source 31 emits light including a wavelength in the infrared region, and the filter 32 cuts light having a wavelength other than the infrared region included in the light emitted from the light source 31. As a light source that emits light including wavelengths in the infrared region, for example, a laser light source can be used. However, if the light source is a laser light source, only a specific wavelength, that is, a wavelength in the infrared region is emitted. Therefore, a filter that cuts light having a wavelength other than the above-described infrared region is not necessary.

The illumination optical system 33 equalizes the intensity of light in the infrared region that has passed through the filter 32. The scanning mechanism 34 includes a pattern plate 34a formed with a plurality of slits that are parallel to each other and equally spaced. The pattern plate 34a is shaped into stripe pattern light P ₂ having a wavelength in the infrared region with equally spaced light and dark each other light in the infrared region obtained by homogenizing the light intensity by the illumination optical system 33. The scanning mechanism 34 moves in the vertical direction S pattern plate 34a with respect to the optical path direction of the stripe pattern light P _2, thereby a stripe pattern light P ₂ is the phase shift of the substrate 5 and the solder bump 4 above. For each phase shift amount, for example, 0 [rad], π / 2 [rad], π [rad], and 3π / 2 [rad]. The projection lens system 35 projects the fringe pattern light P ₂ phase-shifted by the scanning mechanism 34 onto the substrate 5 and the solder bumps 4.

  Next, the operation of the apparatus configured as described above will be described.

  The computer 13 issues a turn-on command to the light source 6 of the first projection optical system 2 and simultaneously issues a turn-off command to the light source 31 of the second projection optical system 30. As a result, the light source 6 is turned on and the light source 31 is turned off.

The light emitted from the light source 6 is transmitted through the filter 7, so that light having a wavelength other than the infrared region is cut, and the intensity thereof is made uniform by the illumination optical system 8 and enters the scanning mechanism 9. Light in the infrared region that is incident on the scanning mechanism 9, the pattern plate is shaped into a stripe pattern light P ₁ of the wavelength of the infrared region having equally spaced light and dark each other by 9a, and the pattern plate 9a stripe pattern light P ₁ of Is shifted in phase shift amounts of, for example, 0 [rad], π / 2 [rad], π [rad], and 3π / 2 [rad]. The phase-shifted fringe pattern light P is projected onto the substrate 5 and the solder bumps 4 by the projection lens system 10 as shown in FIG.

Here, the fringe pattern light P ₁ having a wavelength in the infrared region passes through the semiconductor chip 3 and reaches the surfaces of the solder bumps 4 and the substrate 5. At this time, the stripe pattern light P ₁ is deformed following the surface shape of the solder bump 4 as shown in FIG. 3 and is, for example, 0 [rad], π / 2 [rad], π [rad], 3π / The deformation is performed corresponding to the phase shift for each phase shift amount of 2 [rad]. The projected stripe pattern light P ₁ is scattered by the solder bumps 4 and scattered on the surface of the substrate 5.

The scattered light Q from the solder bumps 4 and the substrate 5 is imaged on the imaging surface of the imaging element 12 by the imaging optical system 11. The image pickup device 12, stripe pattern light P ₁ is imaged scattered light Q from sequential solder bump 4 and the substrate 5 for each phase shift and outputs the image signal.

Computer 13 takes in the image signal output from the imaging element 12, the phase shift of the stripe pattern light _{P 1 (0 [rad],} π / 2 [rad], π [rad], 3π / 2 [rad] A plurality of first phase shift image data corresponding to each) is stored in the memory unit 14.

  Next, the computer 13 issues a turn-on command to the light source 31 of the second projection optical system 30, and simultaneously issues a turn-off command to the light source 6 of the first projection optical system 2. Thereby, the light source 31 is turned on and the light source 6 is turned off.

The light emitted from the light source 31 is transmitted through the filter 32, so that light having a wavelength other than the infrared region is cut, and the intensity is made uniform by the illumination optical system 33 and is incident on the scanning mechanism 34. Light in the infrared region that is incident on the scanning mechanism 34, the pattern plate is shaped into a stripe pattern light P ₂ having a wavelength in the infrared region with equally spaced light and dark each other by 34a, and the pattern plate 34a stripe pattern light P ₂ of For example, 0 [rad], π / 2 [rad], π [rad], and 3π / 2 [rad] are shifted in phase by moving in the vertical direction S with respect to the optical path direction. The phase shifted stripe pattern light P ₂ is projected by the projection lens system 10, as shown in FIG. 2 on the substrate 5 and the solder bump 4.

Similarly to the above, the stripe pattern light P ₂ having a wavelength in the infrared region passes through the semiconductor chip 3, reaches the surfaces of the solder bumps 4 and the substrate 5, and is scattered on the surfaces of the solder bumps 4 and the substrate 5.

The scattered light Q from the solder bumps 4 and the substrate 5 is imaged on the imaging surface of the imaging element 12 by the imaging optical system 11. The image pickup device 12, stripe pattern light P ₂ is imaging the scattered light Q from sequential solder bump 4 and the substrate 5 for each phase shift and outputs the image signal.

Computer 13 takes in the image signal output from the imaging element 12, the phase shift of the stripe pattern light _{P 2 (0 [rad],} π / 2 [rad], π [rad], 3π / 2 [rad] A plurality of second phase shift image data corresponding to each) is stored in the memory unit 14.

  The arithmetic processing unit 15 of the computer 13 uses a plurality of first phase shift image data and a plurality of second phase shift image data, and a phase φ (x at an arbitrary position (x, y) in these phase shift image data. , y) is calculated by calculating the above equation (1), and then the pixel height information h (x, y) at the arbitrary position (x, y) is calculated by calculating the above equation (2).

  Next, the arithmetic processing unit 15 calculates each phase φ (x, y) for all the pixels, and when the phase φ (x, y) is calculated for all the pixels, each phase φ ( x, y) are combined and phase-connected, and converted into height information h (x, y) of the entire substrate 5 and solder bump 4. The arithmetic processing unit 15 extracts the height information h (x, y) of the solder bump 4 from the overall height information h (x, y) of the substrate 5 and the solder bump 4 and displays it on the display device 18. The plurality of first phase shift image data and the plurality of second phase shift image data are acquired through different optical systems of the first projection optical system 2 and the second projection optical system 30, respectively. Therefore, it is not possible to simply synthesize the phase distribution, but it is possible to synthesize them by correcting the phase distribution data based on the respective projection parameters.

  As described above, according to the third embodiment, in the first embodiment, since the projection direction is only one, a shadow portion is always generated. However, the fringe pattern P having the wavelength in the infrared region is used. Is projected from the two directions onto the substrate 5 by the first and second projection optical systems 2 and 30, so that measurement without a shadow portion is possible, and in addition to the first embodiment described above. Similar effects can be achieved. In the above-described embodiment, two examples of the projection optical system have been described. However, the number of projection optical systems is not limited to two.

  In the third embodiment, as in the second embodiment, the height direction moving mechanism 21 that moves the imaging optical system 11 up and down in the height direction of the substrate 5 and the imaging optical system are also provided. 11 and a movement amount measuring device 22 for measuring the movement amount in the height direction. Thereby, even if the height of the solder bump 4 is equal to or greater than the depth of focus of the imaging optical system 11, the height information of the solder bump 4, that is, the gap between the substrate 5 and the semiconductor chip 3 can be calculated.

  In the first to third embodiments, the height information of the solder bump 4 when the semiconductor chip 3 is mounted via the solder bump 4 on the substrate 5, that is, the gap between the substrate 5 and the semiconductor chip 3 is measured. However, the height information h (x, y) of the entire substrate 5 and the solder bump 4 is not limited to this, and the surface shape of the substrate 5 and the solder bump 4 continuously represents in three dimensions. The three-dimensional surface shapes of the substrate 5 and the solder bumps 4 covered with the semiconductor chip 3 can be measured.

  Furthermore, if the technique of the present invention is applied, when measuring the three-dimensional shape of the inspection object covered with the covering, the inspection object covered with the covering is obtained using light having a wavelength that passes through the covering. It is possible to accurately measure the three-dimensional shape.

  Next, other features of the present invention will be described.

The present invention relates to a height measuring apparatus for measuring height information of a plurality of solder bumps formed on a substrate and covered with chip parts made of silicon.
A light source that emits light, a filter that cuts light of a wavelength other than the infrared region included in the light emitted from the light source, and a stripe that has light and darkness at equal intervals between the light in the infrared region that has passed through the filter A projection optical system for projecting the stripe pattern light on the plurality of solder pumps through the chip component;
A scanning mechanism for phase-shifting the fringe pattern light projected onto the plurality of solder bumps for each predetermined phase;
An imaging optical system that forms an image of scattered light from the plurality of solder bumps;
An image sensor that captures images of the plurality of solder bumps imaged by the imaging optical system;
A height information calculation unit that acquires height information of the plurality of solder bumps based on a plurality of phase shift image data acquired by imaging of the imaging element when the scanning mechanism is phase-shifted for each predetermined phase. When,
It is the height measuring device characterized by comprising.

The block diagram which shows 1st Embodiment of the height measuring apparatus which concerns on this invention. The figure which shows the flip chip mounting which performs height measurement with the same apparatus. The figure which shows a deformation | transformation when the stripe pattern light is projected on a solder bump by the same apparatus. The block diagram which shows 2nd Embodiment of the height measuring apparatus which concerns on this invention. The block diagram which shows 3rd Embodiment of the height measuring apparatus which concerns on this invention.

Explanation of symbols

  1: observation object, 2: projection optical system, 3: semiconductor chip, 4: solder pump, 5: substrate, 6: light source, 7: filter, 8: illumination optical system, 9: scanning mechanism, 9a: pattern plate, 10 : Projection lens system, 11: imaging optical system, 12: imaging device, 13: computer, 14: memory unit, 15: arithmetic processing unit, 16: comparison operation unit, 17: dimming instruction unit, 18: display device, 20: Base, 21: Height direction moving mechanism, 22: Movement amount measuring device, 23: Z-axis control unit, 24: Connecting member, 25: Scale plate, 26: Sliding end, 27: Sensor, 30: No. 2 projection optical system, 31: light source, 32: filter, 33: illumination optical system, 34a: pattern plate, 34: scanning mechanism, 35: projection lens system.

Claims (10)

Projecting a predetermined pattern light having a wavelength that is transmitted through the coating onto an inspection object formed on the substrate and covered with the coating;
Obtaining a plurality of phase shift image data from the scattered light from the inspection object when the predetermined pattern light transmitted through the covering is phase-shifted onto the inspection object;
Obtaining height information of the object to be inspected based on the plurality of phase shift image data,
A height measuring method characterized by the above. The height measurement method according to claim 1, wherein the predetermined pattern light having a wavelength in an infrared region is projected onto the inspection object covered with the covering. The height measuring method according to claim 1, wherein fringe pattern light having a wavelength in an infrared region and light and dark at equal intervals is projected onto the inspection object covered with the covering. A projection optical system for projecting a predetermined pattern light having a wavelength that is transmitted through the coating on an inspection object formed on the substrate and covered with the coating;
A scanning mechanism for phase-shifting the predetermined pattern light transmitted through the covering onto the inspection object;
An imaging optical system that forms an image of scattered light from the inspection object;
An image sensor for capturing an image of the inspection object imaged by the imaging optical system;
A height information calculation unit that acquires height information of the object to be inspected based on a plurality of phase shift image data acquired by imaging of the imaging element when the phase is shifted by the scanning mechanism;
A height measuring device comprising: The height measuring apparatus according to claim 4, wherein the projection optical system projects the predetermined pattern light in an infrared region onto the inspection object covered with the covering. The projection optical system includes a light source that emits light,
A filter that cuts off light having a wavelength other than the infrared region of the light emitted from the light source;
The height measuring device according to claim 4, comprising: The object to be inspected is a plurality of spherical solder bumps formed on the substrate surface, and chip parts made of silicon are mounted on the plurality of solder bumps,
The projection optical system projects the predetermined pattern light in the infrared region onto the plurality of solder bumps through the chip component.
The height measuring device according to claim 4. The height measuring apparatus according to claim 4, further comprising a plurality of the projection optical systems in which projection directions of the predetermined pattern light on the inspection object are different from each other. A height direction moving mechanism for moving the imaging optical system in the height direction of the inspection object;
A moving amount measuring device for measuring the moving amount of the imaging optical system in the height direction,
The height information calculation unit includes the height information of the inspection object acquired based on the plurality of phase shift image data and the movement amount of the imaging optical system measured by the movement amount measuring device. Find the original height information of the object to be inspected.
The height measuring device according to claim 4. When the height of the inspection object is equal to or greater than the depth of focus of the imaging optical system, the imaging optical system is moved in the height direction of the inspection object by the height direction moving mechanism.
The height measuring device according to claim 9.

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