JP7494753B2 - METHOD, APPARATUS AND PROGRAM FOR MEASURING ELECTRONIC DEVICE - Google Patents

Description

This disclosure relates to a method, a measuring device, and a measuring program for measuring electronic devices.

Electronic devices are formed by flip-chip bonding a chip to a substrate using bumps. There is a technique for evaluating the mounting condition, such as bump height, by measuring the electrostatic capacitance (for example, Patent Document 1).

JP 2010-56429 A

After flip-chip bonding, it has been difficult to measure the distance (gap) and thickness between the chip and the substrate using optical methods. Therefore, the objective of this invention is to provide a measurement method, measurement device, and measurement program for electronic devices that can measure thickness and distance.

The method for measuring an electronic device according to the present disclosure includes the steps of irradiating light onto a transmissive region of an electronic device formed by flip-chip bonding a first chip and a second chip using bumps, and measuring the thickness of at least a portion of the electronic device and the distance between the first chip and the second chip by spectroscopic interferometry using the reflected light generated when the light is reflected by the electronic device, the transmissive region being a region of the electronic device that is more easily transmissive to light in the thickness direction than the other regions of the electronic device.

The electronic device measuring device according to the present disclosure includes a light source that irradiates light onto a transmissive region of an electronic device formed by flip-chip bonding a first chip and a second chip using bumps, a spectrometer that disperses the reflected light generated when the light is reflected by the electronic device, and a measuring unit that performs spectroscopic interferometry based on the dispersion by the spectrometer to measure at least one of the thickness of the first chip, the thickness of the second chip, and the distance between the first chip and the second chip, and the transmissive region is a region of the electronic device that is more easily transmissive to light in the thickness direction than regions other than the transmissive region.

The electronic device measurement program of the present disclosure causes a computer to execute a process of irradiating light onto a transmissive region of an electronic device formed by flip-chip bonding a first chip and a second chip using bumps, and a process of measuring the thickness of at least a portion of the electronic device and the distance between the first chip and the second chip by spectroscopic interferometry using the reflected light generated when the light is reflected by the electronic device, the transmissive region being a region of the electronic device that is more easily transmissive to light in the thickness direction than regions of the electronic device other than the transmissive region.

The present disclosure makes it possible to provide a measurement method, a measurement device, and a measurement program for measuring thickness and distance of an electronic device.

FIG. 1A is a schematic view illustrating a measurement device according to an embodiment. FIG. 1B is a block diagram showing the hardware configuration of the control unit. FIG. 2A is a plan view illustrating an electronic device. FIG. 2B is a cross-sectional view taken along line AA of FIG. 2A. FIG. 3 is an enlarged view of the vicinity of the transmission region. FIG. 4 is a flow chart illustrating a measurement method.

[Description of the embodiments of the present disclosure]
First, the contents of the embodiments of the present disclosure will be listed and described.

One aspect of the present disclosure is a method for measuring an electronic device, the method comprising the steps of: (1) irradiating a light onto a transmissive region of an electronic device formed by flip-chip bonding a first chip and a second chip using bumps; and measuring a thickness of at least a part of the electronic device and a distance between the first chip and the second chip by a spectroscopic interference method using reflected light generated by the light being reflected by the electronic device, the transmissive region being a region of the electronic device that is more likely to transmit light in a thickness direction than a region other than the transmissive region. The method is capable of measuring the thickness and the distance.
(2) The measuring step may be a step of measuring the thickness of the first chip, the thickness of the second chip, and the distance between the first chip and the second chip by the spectroscopic interferometry, and may measure the thickness of the first chip by the spectroscopic interferometry using the reflected light reflected on the surface of the first chip opposite to the second chip and the reflected light reflected on the surface of the second chip, measure the thickness of the second chip by the spectroscopic interferometry using the reflected light reflected on the surface of the second chip opposite to the first chip, and measure the distance by the spectroscopic interferometry using the reflected light reflected on the surface of the first chip opposite to the second chip. The thickness of the first chip, the thickness of the second chip, and the distance are measured in a single step. Simple and highly accurate measurements are possible.
(3) The step of irradiating the light may be a step of irradiating the light from a surface of the first chip opposite to the second chip, or a surface of the second chip opposite to the first chip. The light is reflected by a surface of the electronic device before reaching the opposite surface from the incident surface. The thickness and distance can be measured by spectroscopic interferometry using the reflected light.
(4) The transmission region includes a first transmission region and a second transmission region, the first transmission region is provided on the first chip and is a region of the first chip that transmits the light more easily than a region of the first chip other than the first transmission region, the second transmission region is provided on the second chip and is a region of the second chip that transmits the light more easily than a region of the second chip other than the second transmission region, the first chip and the second chip are flip-chip bonded such that the first transmission region faces the second transmission region, and in the step of irradiating the light, the light may be irradiated to the first transmission region and the second transmission region. The light passes through the first transmission region and the second transmission region and is reflected by a surface of the electronic device. The thickness and distance can be measured by a spectroscopic interference method using the reflected light.
(5) The first chip may have a light receiving layer and a first metal layer, and the light receiving layer and the first metal layer may be provided in a portion other than the first transmission region. Since the first transmission region does not have the first metal layer, it exhibits high transmittance.
(6) The absorption layer may include indium gallium arsenide, and the first transmission region may include indium phosphide. A light absorptance of the first transmission region is lower than that of the absorption layer.
(7) The second chip may have a second metal layer provided in a portion other than the second transmissive region. The second transmissive region does not have the second metal layer and therefore exhibits high transmittance.
(8) The second transmission region may include silicon. When light passes through silicon, reflected light is generated. The thickness and distance can be measured by spectroscopic interferometry using the reflected light.
(9) The electronic device may have a plurality of the transmissive regions, the transmissive regions being spaced apart from one another in an in-plane direction of the electronic device, the light irradiating step may irradiate the light onto each of the plurality of transmissive regions, and the measuring step may perform the measurement by the spectroscopic interferometry on each of the plurality of transmissive regions. Variations in thickness and variations in distance may be detected.
(10) The transmission area may be located outside a portion of the electronic device where the bumps are provided. Variations in thickness and distance can be detected.
(11) A measuring device for an electronic device, comprising: a light source for irradiating light onto a transmissive region of an electronic device formed by flip-chip bonding a first chip and a second chip using bumps; a spectrometer for dispersing reflected light resulting from the light being reflected by the electronic device; and a measuring unit for performing spectroscopic interferometry based on the dispersion by the spectrometer to measure at least one of the thickness of the first chip, the thickness of the second chip, and the distance between the first chip and the second chip, wherein the transmissive region is a region of the electronic device that is more easily transmissive to light in the thickness direction than regions other than the transmissive region. The measuring device can measure the thickness and distance.
(12) A measurement program for an electronic device, which causes a computer to execute a process of irradiating light onto a transmissive region of an electronic device formed by flip-chip bonding a first chip and a second chip using bumps, and a process of measuring a thickness of at least a part of the electronic device and a distance between the first chip and the second chip by a spectroscopic interference method using reflected light generated when the light is reflected by the electronic device, the transmissive region being a region of the electronic device that transmits light more easily in a thickness direction than regions other than the transmissive region, and capable of measuring the thickness and distance.

[Details of the embodiment of the present disclosure]
Specific examples of a method, device, and program for measuring an electronic device according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

(measuring device)
1A is a schematic diagram illustrating a measuring device 100 according to an embodiment. As shown in FIG. 1A, the measuring device 100 includes a control unit 10, a light source 20, a stage 21, a spectrometer 22, a light receiving unit 24, a beam splitter 26, and a camera 28. The measuring device 100 measures the thickness and distance of at least a part of the electronic device 30 in the Z-axis direction. The Z-axis direction is the propagation direction of light. The X-axis direction and the Y-axis direction are the extension directions of the sides of the electronic device 30. The X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other.

The main surface of the stage 21 is located in the XY plane. The normal direction of the main surface of the stage 21 is the Z-axis direction. The electronic device 30 is placed on the main surface of the stage 21. The stage 21 is a movable stage equipped with a motor and the like. The position of the electronic device 30 on the stage 21 in the XY plane and the height in the Z-axis direction can be changed.

The light source 20 emits light. The light emitted from the light source 20 includes multiple lights with different wavelengths. The wavelengths are, for example, in the infrared band, such as 800 nm to 1100 nm. The light source 20 is, for example, a superluminescent diode (SLD) light source, a light emitting diode (LED) light source, a halogen light source, or the like.

The beam splitter 26 includes a half mirror and transmits part of the intensity of the incident light and reflects another part in a direction perpendicular to the incident direction of the light. The spectroscope 22 includes, for example, a prism or a diffraction grating, and separates the incident light into wavelengths. The light receiving unit 24 includes a light receiving element such as a photodiode, and outputs an electrical signal according to the intensity of the light by receiving the light. The camera 28 is sensitive to, for example, infrared light, and captures, for example, a mark on the electronic device 30.

A lens may be disposed between the light source 20 and the beam splitter 26. A lens may be disposed between the beam splitter 26 and the electronic device 30. A lens may be disposed between the beam splitter 26 and the spectrometer 22. Light may be propagated through optical fibers between the light source 20 and the beam splitter 26, between the beam splitter 26 and the electronic device 30, and between the beam splitter 26 and the spectrometer 22.

The control unit 10 includes, for example, a computer, and is electrically connected to the light source 20, the stage 21, the light receiving unit 24, and the camera 28. The control unit 10 functions as a position control unit 12, a light control unit 13, and a measurement unit 14. The position control unit 12 changes the position of the electronic device 30 on the stage 21, and aligns the electronic device 30 with the optical system (light source 20, spectroscope 22, light receiving unit 24, beam splitter 26). The light control unit 13 switches the light source 20 on and off, controls the wavelength of the light emitted from the light source 20, and so on. The measurement unit 14 measures the thickness and distance according to the intensity of each wavelength of the light received by the light receiving unit 24.

Figure 1B is a block diagram showing the hardware configuration of the control unit 10. As shown in Figure 1B, the control unit 10 includes a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102, a storage device 104, and an interface 106. The CPU 101, the RAM 102, the storage device 104, and the interface 106 are connected to each other via a bus or the like. The RAM 102 is a volatile memory that temporarily stores programs, data, and the like. The storage device 104 is, for example, a ROM (Read Only Memory), a solid state drive (SSD) such as a flash memory, or a hard disk drive (HDD). The storage device 104 stores the measurement program described below, and the like.

When the CPU 101 executes a program stored in the RAM 102, the position control unit 12, light control unit 13, measurement unit 14, and the like shown in FIG. 1A are realized in the control unit 10. Each unit of the control unit 10 may be hardware such as a circuit.

The dashed lines in FIG. 1A represent light. Light emitted from the light source 20 enters the beam splitter 26. A portion of the light is reflected by the beam splitter 26, propagates in the Z-axis direction, and enters the electronic device 30. As described below, the light is reflected by multiple surfaces in the electronic device 30, resulting in multiple reflected lights. The light reflected by the electronic device 30 propagates in the Z-axis direction and enters the beam splitter 26. A portion of the reflected light passes through the beam splitter 26 and enters the spectroscope 22. The light that enters the spectroscope 22 is split by the spectroscope 22 and then enters the light receiving unit 24. The light receiving unit 24 measures the intensity of the light. The control unit 10 obtains the intensity and measures the thickness and distance using spectroscopic interferometry.

(Electronic Device)
Fig. 2A is a plan view illustrating an electronic device 30. Fig. 2B is a cross-sectional view taken along line A-A in Fig. 2A. Fig. 3 is an enlarged view of the vicinity of the transmissive region. Although Fig. 3 is a cross-sectional view, hatching of the substrate 41, the n-type semiconductor layer 60, and the substrate 51 is omitted.

As shown in Figures 2A to 3, the electronic device 30 includes a sensor chip 40 (first chip) and an IC (Integrated Circuit) chip 50 (second chip). The sensor chip 40 is, for example, a Focal Plane Array (FPA) sensor. The IC chip 50 is a circuit board and has, for example, a readout integrated circuit (ROIC). The sensor chip 40 outputs an electrical signal by receiving infrared light. The IC chip 50 receives the electrical signal from the sensor chip 40. The electronic device 30 is a light receiving device that senses light such as infrared light.

As shown in FIG. 2A, the shape of the sensor chip 40 and the shape of the IC chip 50 in the XY plane are rectangular. The length Y1 of the sensor chip 40 in the Y-axis direction is, for example, 5.5 mm. The length X1 in the X-axis direction is, for example, 10.0 mm. The length Y2 of the IC chip 50 in the Y-axis direction is, for example, 7.5 mm. The length X2 in the X-axis direction is, for example, 12.0 mm.

As shown in FIG. 2B, the sensor chip 40 and the IC chip 50 face each other in the Z-axis direction and are flip-chip bonded using multiple bumps 34. The sensor chip 40 and the IC chip 50 are spaced apart in the Z-axis direction, and the space between them is filled with underfill 36.

(sensor chip)
The sensor chip 40 has a substrate 41 and a semiconductor layer 42. The semiconductor layer 42 is provided on the surface of the substrate 41 facing the IC chip 50. Of the surfaces of the sensor chip 40, the surface on the IC chip 50 side is referred to as surface 48. The surface opposite surface 48 is referred to as surface 47. Surface 47 is coated with an anti-reflection film 43. The anti-reflection film 43 is formed of an insulator such as silicon nitride (SiN) or silicon dioxide (SiO ₂ ).

As shown in FIG. 3, the semiconductor layer 42 includes an n-type semiconductor layer 60, a light receiving layer 62, a p-type semiconductor layer 64, and a contact layer 66. The n-type semiconductor layer 60 covers the entire surface of the substrate 41 on the IC chip 50 side. The surface 48 is formed of the n-type semiconductor layer 60. The light receiving layer 62, the p-type semiconductor layer 64, and the contact layer 66 are not provided on the outer periphery of the n-type semiconductor layer 60 in the XY plane, and instead, a plurality of electrodes 45 and marks 46 are provided. A transmissive region 32 is also provided on the outer periphery. The transmissive region 32 will be described later.

The light receiving layer 62, the semiconductor layer 63, and the p-type semiconductor layer 64 are laminated in order on the surface of the n-type semiconductor layer 60 on the IC chip 50 side, excluding the outer periphery. The semiconductor layer 63 and the p-type semiconductor layer 64 form a plurality of mesas 67. The plurality of mesas 67 are arranged in an array in the XY plane. One mesa 67 corresponds to, for example, one pixel. The mesa 67 protrudes toward the IC chip 50 side. The contact layer 66 is provided on the surface of the p-type semiconductor layer 64, at the tip of the mesa 67 on the IC chip 50 side. An electrode 44 is provided on the contact layer 66. The plurality of mesas 67 are spaced apart from each other. The electrodes 44 and 45 are formed of a metal such as gold (Au) and platinum (Pt). The electrode 44 is an electrode for signals. The electrode 45 is a ground electrode. The mark 46 is formed of a metal such as gold (Au). The mark 46 is used as an alignment mark during mounting.

The substrate 41 is a semiconductor substrate formed of, for example, indium phosphide (InP). The n-type semiconductor layer 60 is formed of, for example, n-type InP. The p-type semiconductor layer 64 is formed of, for example, p-type InP. The light-receiving layer 62 is formed of, for example, indium gallium arsenide (InGaAs). The semiconductor layer 63 is formed of, for example, n-type InP. The contact layer 66 is formed of, for example, p-type InGaAs. The light-receiving layer 62 absorbs, for example, infrared light, and has a high absorption rate, especially for light with a wavelength in the range of 1100 nm to 1700 nm. The light-receiving layer 62 absorbs light and generates electrons and holes. The band gaps of the substrate 41, the n-type semiconductor layer 60, and the p-type semiconductor layer 64 are larger than the energy of infrared light. The light absorption rates of the substrate 41, the n-type semiconductor layer 60, and the p-type semiconductor layer 64 are smaller than those of the light-receiving layer 62.

(IC chip)
The IC chip 50 has a substrate 51 and electrodes 52 and 53. The substrate 51 is formed of, for example, silicon (Si). The surface of the substrate 51 on the sensor chip 40 side is defined as a surface 56. The surface opposite to the surface 56 is defined as a surface 55. A plurality of electrodes 52, a plurality of electrodes 53, and a mark 54 are provided on the surface 56 of the substrate 51. The electrodes 52 and 53 are formed of a metal such as aluminum (Al) and platinum (Pt). The electrode 52 is a signal electrode. The electrode 53 is a ground electrode. The mark 54 is formed of a metal such as Au. The mark 54 is used as an alignment mark during mounting. The substrate 51 may have wiring patterns on the surfaces 55, 56, and inside the substrate 51, for example.

The electrode 44 of the sensor chip 40 and the electrode 52 of the IC chip 50 face each other and are electrically connected by the bump 34. The electrode 45 of the sensor chip 40 and the electrode 53 of the IC chip 50 face each other and are electrically connected by the bump 34. The bump 34 is formed of a metal such as solder.

The light receiving layer 62 of the sensor chip 40 generates carriers (electrons and holes) by receiving light such as infrared light. The electrical signal (current) generated by the sensor chip 40 is input to the IC chip 50 through the electrodes 45 and 44 and the bump 34. The IC chip 50 reads the electrical signal and generates, for example, image information.

(Production method)
A method for manufacturing the electronic device 30 will now be described. Electrodes 52 and 53 and marks 54 are provided by a vacuum deposition method or the like on a silicon wafer (substrate 51) on which an electronic circuit and a wiring pattern are formed. The silicon wafer is polished, diced, and the like to form an IC chip 50.

A semiconductor layer 42 is epitaxially grown on the surface of an InP wafer (substrate 41) by metal organic chemical vapor deposition (MOCVD) or the like. A mesa 67 is formed, for example, by dry etching. Electrodes 44 and 45 and a mark 46 are provided by vacuum deposition or the like. An anti-reflection film 43 is deposited on the back surface of the wafer by chemical vapor deposition (CVD) or the like. The wafer is diced or the like to form a sensor chip 40.

Solder is placed on each of the electrodes 44, 45, 52, and 53. The sensor chip 40 and the IC chip 50 are aligned by aligning the marks 46 and 54. The electrodes 44 and 52 face each other, and the electrodes 45 and 53 face each other. A reflow process is performed, and the sensor chip 40 and the IC chip 50 are flip-chip bonded. The molten solder connects to each other, forming the bumps 34. After flip-chip bonding, a resin such as epoxy is filled between the sensor chip 40 and the IC chip 50 to form the underfill 36.

The measuring device 100 shown in FIG. 1A measures thicknesses and distances in the completed electronic device 30. Specifically, as shown in FIG. 3, it measures the thickness T1 between faces 47 and 48 of the sensor chip 40 in the Z-axis direction, the thickness T2 between faces 55 and 56 of the IC chip 50, and the distance (gap) g between the sensor chip 40 and the IC chip 50. The measuring device 100 irradiates light onto the three transmissive regions 32 of the electronic device 30. The three transmissive regions 32 are referred to as transmissive regions 32a, 32b, and 32c, respectively.

As shown in FIG. 2A, the three transparent regions 32a, 32b, and 32c are located outside the portion of the electronic device 30 where the bumps 34 are provided. The transparent region 32a is located near one of the four vertices of the sensor chip 40 in the XY plane, the transparent region 32b is located near another vertex, and the transparent region 32c is located near yet another vertex. The transparent regions 32a and 32b are aligned in the X-axis direction. The transparent regions 32a and 32c are aligned in the Y-axis direction. The transparent regions 32a, 32b, and 32c are each circular. The diameter D1 of one transparent region 32 is, for example, 80 μm.

As shown in Figures 2B and 3, one transparent region 32 includes transparent regions 37 and 38. Transparent region 37 (first transparent region) is a transparent region of sensor chip 40. Transparent region 38 (second transparent region) is a transparent region of IC chip 50. Transparent region 37 and transparent region 38 face each other in the Z-axis direction and form transparent region 32. Transparent region 32 includes surface 47 to surface 55 of electronic device 30 in the Z-axis direction.

The transparent region 37 is more likely to transmit light than the other regions of the sensor chip 40. The transparent region 37 has a substrate 41 and an n-type semiconductor layer 60. The transparent region 37 does not have an anti-reflection film 43, and the surface 47 is exposed. The anti-reflection film 43 can be removed by, for example, etching. As shown in FIG. 3, the light receiving layer 62, the p-type semiconductor layer 64, the contact layer 66, the electrodes 44 and 45, and the mark 46 are not provided in the transparent region 37. The mark 46 and the transparent region 37 are spaced apart in the X-axis direction. The distance D2 between the mark 46 and the transparent region 37 shown in FIG. 3 is, for example, several μm to several tens of μm.

The sensor chip 40 has a light receiving layer 62 in the portion other than the transmission region 37. For example, 90% or more of the infrared light is absorbed by the light receiving layer 62, and almost no light is transmitted below the light receiving layer 62. Since the light receiving layer 62 is not provided in the transmission region 37, infrared light is not easily absorbed and is easily transmitted. The sensor chip 40 has a metal (electrodes 44 and 45, bump 34) in the portion other than the transmission region 37. The reflectance of the metal to light is higher than that of the substrate 41, for example, 90% or more for infrared light. The electrodes 44 and 45, the mark 46, and the bump 34 are not provided in the transmission region 37. Therefore, the transmission region 37 transmits light more easily than the other regions of the sensor chip 40 other than the transmission region 37. The transmission region 37 has a particularly high transmittance for light having a wavelength of 960 nm or more. For example, 50% or more of light having a wavelength of 960 nm or more that is irradiated from the Z-axis direction is transmitted through the transmission region 37.

In the IC chip 50, metal layers (second metal layers) such as electrodes 52 and 53, bumps 34, marks 54, and wiring patterns (not shown) are provided in the areas other than the transmissive area 38. On the other hand, no metal layer is provided in the transmissive area 38. The distance between the transmissive area 38 and the marks 54 is approximately the same as the distance D2 in FIG. 3. The transmissive area 38 has a higher light transmittance than the areas of the IC chip 50 other than the transmissive area 37. The transmissive area 38 has a particularly high transmittance for light having a wavelength of 960 nm or more. For example, 50% or more of light having a wavelength of 960 nm or more that is irradiated from the Z-axis direction passes through the transmissive area 38.

(Measuring method)
FIG. 4 is a flow chart illustrating a measurement method. As shown in FIG. 4, the transmissive region 32 of the electronic device 30 is aligned with the optical system of the measurement device 100 (step S10). The camera 28 shown in FIG. 1A captures the marks 46 and 54 of the electronic device 30. The control unit 10 acquires an image from the camera 28 and recognizes the positions of the marks 46 and 54. The position shifted from the positions of the marks 46 and 54 by several μm in the X-axis direction, for example, is the transmissive region 32. The control unit 10 recognizes the transmissive region 32 from the positions of the marks 46 and 54. The position control unit 12 moves the electronic device 30 using the stage 21 to align the transmissive region 32 with the optical system. One of the three transmissive regions 32a, 32b, and 32c and the optical axis of the light incident from the beam splitter 26 are aligned in the Z-axis direction.

The light control unit 13 causes the light source 20 to emit light. The light is broadband infrared light that includes multiple wavelengths. The wavelengths included are in the range of 800 nm to 1100 nm, for example. The light is reflected by the beam splitter 26 and enters the electronic device 30 (step S12). The light is reflected by the electronic device 30, generating reflected light. The reflected light passes through the beam splitter 26 and enters the spectroscope 22. The measurement unit 14 performs spectroscopic interferometry using the reflected light to measure the thickness and gap (step S14). The measurement device 100 performs the above measurements in all three transmission regions 32.

Reflected light will be described in detail with reference to FIG. 3. As shown in FIG. 3, light L0 propagates in the Z-axis direction and enters the transmissive region 32 of the electronic device 30 from the surface 47 side of the sensor chip 40.

The electronic device 30 is exposed to air, for example, on the stage 21. As shown in FIG. 3, in the transmissive region 32, the substrate 41 of the sensor chip 40, the n-type semiconductor layer 60, the underfill 36, and the substrate 51 of the IC chip 50 are aligned in the Z-axis direction. The transmissive region 32 includes the interface between the air and the substrate 41, the interface between the n-type semiconductor layer 60 and the underfill 36, the interface between the underfill 36 and the substrate 51, and the interface between the substrate 51 and the air.

The refractive index of air is 1.0. The refractive index of the substrate 41 and the n-type semiconductor layer 60 is approximately 3.2. The underfill 36 is made of, for example, a resin, and has a refractive index of approximately 1.5. The refractive index of the substrate 51 is approximately 3.2 to 3.4. The refractive index changes at the above four interfaces. The refractive indexes of the layers on both sides of the interface are different from each other. When light L0 enters the interface, a part of it is reflected in the opposite direction to light L0.

A portion of the light L0 incident on surface 47 is reflected at the interface (surface 47) between the air and the substrate 41. A portion of the light passing through the sensor chip 40 is reflected at the interface (surface 48) between the n-type semiconductor layer 60 and the underfill 36. A portion of the light passing through the underfill 36 is reflected at the interface (surface 56) between the underfill 36 and the substrate 51. A portion of the light passing through the IC chip 50 is reflected at the interface (surface 55) between the substrate 51 and the air. The reflected light occurring at surface 47 is referred to as reflected light L1. The reflected light occurring at surface 48 is referred to as reflected light L2. The reflected light occurring at surface 56 is referred to as reflected light L3. The reflected light occurring at surface 55 is referred to as reflected light L4.

Light L0 is perpendicular to surface 47, propagates downward from the Z-axis in FIG. 3, and enters electronic device 30 from surface 47. Reflected light L1, L2, L3, and L4 propagate upward from the Z-axis, pass through beam splitter 26 in FIG. 1A, and enter spectrometer 22.

Reflected light L1 and reflected light L2 interfere with each other, generating interference light. Spectrometer 22 separates the interference light, and light-receiving unit 24 detects the intensity of the interference light for each wavelength. Measurement unit 14 measures thickness T1 between surface 47 and surface 48 of sensor chip 40 based on the wavelength and intensity. Reflected light L2 and reflected light L3 interfere with each other, generating interference light. Spectrometer 22 and light-receiving unit 24 detect the intensity for each wavelength. Measurement unit 14 measures gap g. Reflected light L3 and reflected light L4 interfere with each other, generating interference light. Spectrometer 22 and light-receiving unit 24 detect the intensity for each wavelength. Measurement unit 14 measures thickness T2 between surface 56 and surface 55 of IC chip 50.

According to the embodiment, light L0 is irradiated onto the transparent region 37 of the electronic device 30. The transparent region 37 transmits light more easily than other portions of the electronic device 30 than the transparent region 37. For example, the light L0 enters the electronic device 30 from surface 47 and reaches the opposite surface 55. A portion of the light L0 is reflected by the multiple surfaces (surfaces 47, 48, 55, and 56) of the electronic device 30, resulting in reflected light. By using the reflected light, the thickness T1 of the sensor chip 40, the thickness T2 of the IC chip 50, and the distance (gap g) between the sensor chip 40 and the IC chip 50 can be measured in a single process using spectroscopic interference.

Because the images of marks 46 and 54 are blurred due to light scattering and spherical aberration, it is difficult to perform accurate measurements using the images. It is also difficult to measure thickness using images.

According to the embodiment, the light L0 is irradiated onto the transmission region 32, and the reflected light is used to perform the spectroscopic interferometry. The control unit 10 measures the thickness T1 of the sensor chip 40 by the spectroscopic interferometry using the reflected light L1 and the reflected light L2. The control unit 10 measures the gap g by the spectroscopic interferometry using the reflected light L2 and the reflected light L3. The control unit 10 measures the thickness T2 of the IC chip 50 by the spectroscopic interferometry using the reflected light L3 and the reflected light L4. The thicknesses T1 and T2, as well as the gap g, can be measured in a single process. Simple and highly accurate measurements are possible. The control unit 10 may measure one of the thicknesses T1 and T2, and the gap g. The control unit 10 can also measure the thickness of the electronic device 30 by the spectroscopic interferometry using the reflected light L1 and the reflected light L4. The control unit 10 measures the thickness of at least a part of the electronic device 30.

As shown in FIG. 3, light L0 may be incident from surface 47 of sensor chip 40, or from surface 55 of IC chip 50. By irradiating light L0 from the outermost surface of electronic device 30, reflected light L1, L2, L3, and L4 are generated from multiple surfaces (surfaces 47, 48, 55, and 56) within electronic device 30. By using spectral interferometry, thicknesses T1 and T2 and gap g can be measured at the same time.

If light L0 is tilted from the Z-axis direction, the thickness and gap will be measured in the tilted direction, resulting in poor accuracy. Therefore, as shown in Figure 3, it is preferable for light L0 to propagate along the Z-axis direction and be incident perpendicularly on surfaces 47 and 55. This allows the thicknesses T1 and T2 and gap g in the Z-axis direction to be accurately measured.

As shown in FIG. 2B, the transmissive region 32 includes a transmissive region 37 of the sensor chip 40 and a transmissive region 38 of the IC chip 50. The transmissive region 37 and the transmissive region 38 face each other in the Z-axis direction. Light L0 propagates in the Z-axis direction and is incident on the transmissive region 37 and the transmissive region 38. The transmissive region 37 includes surfaces 47 and 48. The transmissive region 38 includes surfaces 55 and 56. Reflected light occurs at these surfaces. The thicknesses T1 and T2 and the gap g can be measured by spectral interferometry.

For example, if thickness T1 and gap g are measured but thickness T2 is not measured, IC chip 50 may not have transparent region 38. Light L0 enters from surface 47, passes through transparent region 37, and reaches surface 56. Reflected light is generated at each of surfaces 47, 48, and 56. Thickness T1 and gap g can be measured by spectral interferometry. For example, if thickness T2 and gap g are measured but thickness T1 is not measured, sensor chip 40 may not have transparent region 37. Light L0 enters from surface 55 and reaches surface 48. Thickness T2 and gap g are measured by spectral interferometry.

The sensor chip 40 is, for example, a sensor that detects infrared light, and has a light receiving layer 62 and a metal layer (electrodes 44 and 45, mark 46, first metal layer). The light receiving layer 62 is, for example, an InGaAs layer, and is sensitive to infrared light. When light L0 is irradiated onto the light receiving layer 62, it is absorbed, so reflected light L2, L3, and L4 are unlikely to be generated. Metals have a high reflectance, for example, 90% or more. When light L0 is reflected by a metal such as mark 46, the intensity of reflected light L3 and L4 generated by the IC chip 50 decreases. This makes measurement by spectroscopic interference difficult.

The transmissive region 37 of the sensor chip 40 does not have a light receiving layer 62. The transmissive region 37 is formed of an InP substrate 41 and an n-type semiconductor layer 60. The band gap of InP is larger than the energy of infrared light. The absorptance of the substrate 41 and the n-type semiconductor layer 60 is lower than that of the light receiving layer 62. In other words, the light absorptance of the transmissive region 37 is lower than that of the other parts of the sensor chip 40 other than the transmissive region 37. In addition, no metal layers (electrodes 44 and 45, mark 46, etc.) are provided in the transmissive region 37. The reflectance of the transmissive region 37 is lower than that of the other parts of the sensor chip 40 other than the transmissive region 37. The anti-reflection film 43 is also not provided. In other words, the transmissive region 37 has a higher transmittance than that of the other parts of the sensor chip 40 other than the transmissive region 37.

The IC chip 50 has metal layers (electrodes 52 and 53, mark 54, etc.). The transmissive region 38 is formed of Si and has no metal layers. The reflectance of the transmissive region 38 is lower than the portions other than the transmissive region 38. In other words, the transmissive region 38 has a higher transmittance than the portions other than the transmissive region 38.

Light L0 passes through the transparent region 37 of the sensor chip 40, propagates to the IC chip 50, and passes through the transparent region 38 of the IC chip 50. Light L0 is reflected by surfaces 47, 48, 56, and 55. The thicknesses T1 and T2 and the gap g can be measured by spectroscopic interference using the reflected light.

The light transmittance of the transmission region 37 is, for example, 50% or more. The light L0 incident from the surface 47 reaches the IC chip 50 while maintaining sufficient intensity. The intensities of the reflected light L3 and L4 generated by the IC chip 50 are suitable for the spectroscopic interference method. If the transmittance is too high, the intensity of the reflected light L1 will be low. The transmittance of the transmission region 37 is preferably, for example, 90% or less. The transmittance of the underfill 36 is, for example, 50% or more. The transmittance of the transmission region 38 is, for example, 50% or more. The light L0 incident from the surface 56 reaches the surface 55 while maintaining sufficient intensity. The intensity of the reflected light L4 will be suitable for the spectroscopic interference method. If the transmittance is too high, the intensity of the reflected light L3 will be low. The transmittance of the transmission region 38 is preferably, for example, 90% or less. If the difference in refractive index between the materials on both sides of the surface is too small, the transmittance at the surface will be high and the intensity of the reflected light will be low. The refractive index difference is preferably, for example, 1 or more. The refractive index difference between the air sandwiching surface 47 and substrate 41 is approximately 2.2. The refractive index difference between the underfill 36 (with a refractive index of approximately 1.5) sandwiching surface 56 and the transmissive region 38 (substrate 51) is 1.7 or more and 1.8 or less.

In the embodiment, the sensor chip 40 is an array chip that includes a plurality of mesas 67 and detects infrared light. The IC chip 50 is a circuit board that includes a read circuit (ROIC). The electronic device 30 may include a chip other than the sensor chip 40, or may include a chip other than the IC chip 50.

The electronic device 30 has three transparent regions 32a, 32b, and 32c. The three transparent regions 32a, 32b, and 32c are spaced apart from one another. By performing the measurements of FIG. 4 in each of the three transparent regions 32a, 32b, and 32c, the thicknesses T1 and T2 and the gap g in each of the three transparent regions 32a, 32b, and 32c are obtained. The variation in thickness T1, the variation in thickness T2, and the variation in gap g can be detected.

As shown in FIG. 2A, the three transparent regions 32a, 32b, and 32c are preferably located outside the portion of the electronic device 30 where the bump 34 is provided, and are particularly preferably located near the apex of the electronic device 30. The variation in thickness T1, the variation in thickness T2, and the variation in gap g can be detected with high accuracy.

The sensor chip 40 and the IC chip 50 are preferably parallel in the XY plane. However, there is a risk that the sensor chip 40 may be mounted at an angle to the IC chip 50 during flip-chip bonding. It is important to measure the variation in the gap g. By comparing the gap g in the transparent region 32a with the gap g in the transparent region 32b, the angle in the X-axis direction can be detected. By comparing the gap g in the transparent region 32a with the gap g in the transparent region 32c, the angle in the Y-axis direction can be detected. The gap g is, for example, 0.03 mm ± 0.02 mm. The number of transparent regions 32 may be three or more, and for example, four transparent regions 32 may be provided near the four vertices of the electronic device 30.

In the manufacturing process of the IC chip 50, a silicon wafer is polished, and the polished wafer is cut. Variations in the thickness of the wafer caused by polishing may also occur in the thickness T2. According to the embodiment, the variation in the thickness T2 can be detected. For example, the thickness T2 is preferably 0.58 mm ± 0.02 mm. In the manufacturing process of the sensor chip 40, there is also a risk of variation in the thickness T1. According to the embodiment, the variation in the thickness T1 can be detected. For example, the thickness T1 of the sensor chip 40 is preferably 0.58 mm ± 0.02 mm.

Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the specific embodiments, and various modifications and variations are possible within the scope of the gist of the present disclosure as described in the claims.

REFERENCE SIGNS LIST 10 Control unit 12 Position control unit 13 Light control unit 14 Measurement unit 20 Light source 21 Stage 22 Spectrometer 24 Light receiving unit 26 Beam splitter 28 Camera 30 Electronic device 32, 32a, 32b, 32c, 37, 38 Transmitting area 34 Bump 36 Underfill 40 Sensor chip 41, 51 Substrate 42, 63 Semiconductor layer 43 Anti-reflection film 44, 45, 52, 53 Electrode 46, 54 Mark 47, 48, 55, 56 Surface 50 IC chip 60 n-type semiconductor layer 62 Light receiving layer 64 p-type semiconductor layer 66 Contact layer 67 Mesa 100 Measurement device 101 CPU
102 RAM
104 Storage device 106 Interface

Claims (11)

irradiating light onto a transmissive region of an electronic device formed by flip-chip bonding a first chip and a second chip using bumps;
measuring a thickness of at least a portion of the electronic device and a distance between the first chip and the second chip by spectroscopic interferometry using reflected light generated by the light being reflected by the electronic device;
the transmissive region is a region of the electronic device that transmits light more easily in a thickness direction than a region other than the transmissive region,
the measuring step is a step of measuring a thickness of the first tip, a thickness of the second tip, and a distance between the first tip and the second tip by the spectroscopic interferometry;
measuring a thickness of the first chip by a spectroscopic interferometry using a reflected light reflected on a surface of the first chip opposite to the second chip and a reflected light reflected on a surface of the first chip on the second chip side;
measuring a thickness of the second chip by a spectroscopic interferometry using a reflected light reflected on a surface of the second chip on the side of the first chip and a reflected light reflected on a surface opposite to the first chip;
A measurement method for an electronic device that measures the distance by spectroscopic interferometry using reflected light reflected on the surface of the first chip facing the second chip and reflected light reflected on the surface of the second chip facing the first chip. 2. The method for measuring an electronic device according to claim 1, wherein the step of irradiating light is a step of irradiating light from a surface of the first chip opposite the second chip, or from a surface of the second chip opposite the first chip. irradiating light onto a transmissive region of an electronic device formed by flip-chip bonding a first chip and a second chip using bumps;
measuring a thickness of at least a portion of the electronic device and a distance between the first chip and the second chip by spectroscopic interferometry using reflected light generated by the light being reflected by the electronic device;
the transmissive region is a region of the electronic device that transmits light more easily in a thickness direction than a region other than the transmissive region,
the transmission region includes a first transmission region and a second transmission region,
the first transmission region is provided in the first chip and is a region of the first chip that transmits the light more easily than a region of the first chip other than the first transmission region;
the second transmission region is provided in the second chip and is a region of the second chip that transmits the light more easily than a region other than the second transmission region,
the first chip and the second chip are flip-chip bonded such that the first transmitting region faces the second transmitting region;
The method for measuring an electronic device, wherein in the step of irradiating light, the light is irradiated onto the first transmission region and the second transmission region. the first chip has a light receiving layer and a first metal layer;
The method for measuring an electronic device according to claim 3 , wherein the light receiving layer and the first metal layer are provided in a portion other than the first transmissive region. the light receiving layer comprises indium gallium arsenide;
The method of claim 4 , wherein the first transmissive region comprises indium phosphide. The method for measuring an electronic device according to claim 3 , wherein the second chip has a second metal layer provided in a portion other than the second transmissive region. The method of measuring an electronic device according to claim 3 , wherein the second transmissive region includes silicon. The electronic device has a plurality of the transmissive regions,
The plurality of transmissive regions are spaced apart from one another in an in-plane direction of the electronic device,
In the step of irradiating light, the light is irradiated onto each of the plurality of transmission regions;
The method for measuring an electronic device according to claim 1 , wherein the measuring step is a step of performing the measurement by the spectroscopic interferometry in each of the plurality of transmission regions. The method for measuring an electronic device according to claim 1 , wherein the transmission region is positioned outside a portion of the electronic device where the bumps are provided. a light source that irradiates light onto a transmissive region of an electronic device formed by flip-chip bonding a first chip and a second chip using bumps;
a spectrometer for splitting reflected light generated when the light is reflected by the electronic device;
A measuring unit that performs a spectroscopic interferometry based on the spectroscope and measures at least one of a thickness of the first tip, a thickness of the second tip, and a distance between the first tip and the second tip,
the transmissive region is a region of the electronic device that transmits light more easily in a thickness direction than a region other than the transmissive region,
the measurement unit measures a thickness of the first tip, a thickness of the second tip, and a distance between the first tip and the second tip by the spectroscopic interferometry;
measuring a thickness of the first chip by a spectroscopic interferometry using a reflected light reflected on a surface of the first chip opposite to the second chip and a reflected light reflected on a surface of the first chip on the second chip side;
measuring a thickness of the second chip by a spectroscopic interferometry using a reflected light reflected on a surface of the second chip on the side of the first chip and a reflected light reflected on a surface opposite to the first chip;
A measuring apparatus for an electronic device that measures the distance by spectroscopic interferometry using reflected light reflected on the surface of the first chip facing the second chip and reflected light reflected on the surface of the second chip facing the first chip . On the computer,
A process of irradiating light onto a transparent region of an electronic device formed by flip-chip bonding a first chip and a second chip using bumps;
measuring a thickness of at least a portion of the electronic device and a distance between the first chip and the second chip by spectroscopic interferometry using reflected light generated by the light being reflected by the electronic device;
the transmissive region is a region of the electronic device that transmits light more easily in a thickness direction than a region other than the transmissive region,
the measuring process is a process of measuring a thickness of the first tip, a thickness of the second tip, and a distance between the first tip and the second tip by the spectroscopic interferometry;
measuring a thickness of the first chip by a spectroscopic interferometry using a reflected light reflected on a surface of the first chip opposite to the second chip and a reflected light reflected on a surface of the first chip on the second chip side;
measuring a thickness of the second chip by a spectroscopic interferometry using a reflected light reflected on a surface of the second chip on the side of the first chip and a reflected light reflected on a surface opposite to the first chip;
A measurement program for an electronic device that measures the distance by spectroscopic interferometry using reflected light reflected on the surface of the first chip facing the second chip and reflected light reflected on the surface of the second chip facing the first chip.

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