Patent Publication Number: US-2023152086-A1

Title: Heterogeneous integration detecting method and heterogeneous integration detecting apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 110143061, filed on Nov. 18, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND 
     Technical Field 
     The disclosure relates to a detecting method and a detecting apparatus, and in particular to a heterogeneous integration detecting method and a heterogeneous integration detecting apparatus. 
     Description of Related Art 
     In a packaging technology of a 3 dimension integrated circuit (3D IC), a through-silicon via (TSV) technology enables electrical signals to be transmitted in a shorter vertical path, thereby shortening the length of the conductive path to greatly reduce an RC delay problem. 
     When an optical non-destructive method is used to detect the depth of a through-silicon via, if the incident light is not perpendicular to a surface of a sample, the depth of the through-silicon via cannot be detected correctly. As an aperture of the through-silicon via is becoming increasingly smaller, its aspect ratio increases. The incident light not being perpendicular to the surface of the sample causes the accuracy of the optical non-destructive detection to decrease substantially. 
     SUMMARY 
     The disclosure provides a heterogeneous integration detecting method and a heterogeneous integration detecting apparatus, which prevent a substantial decrease in the accuracy of optical non-destructive detection. 
     A heterogeneous integration detecting method of the disclosure includes the following. Under a condition of maintaining a same relative distance between a sample and an interference objective lens, a relative posture of the interference objective lens and the sample is continuously adjusted according to a change of an image of the sample in a field of view of the interference objective lens, until a first optical axis of the interference objective lens is determined to be substantially perpendicular to a surface of the sample according to the image. The interference objective lens is replaced with an imaging objective lens, and a geometric profile of at least one via of the sample is detected; a second optical axis of the imaging objective lens after replacement overlaps with the first optical axis of the interference objective lens before replacement. 
     The heterogeneous integration detecting apparatus of the disclosure includes a first moving mechanism, an optical system, a sample carrier, and an analyzer. The optical system is installed on the first moving mechanism. The optical system includes an interference objective lens and an imaging objective lens. The sample carrier is used to carry a sample. The analyzer is used to obtain an image output by the optical system. Under a condition of maintaining a same relative distance between the sample and the interference objective lens, a relative posture of the interference objective lens and the sample is continuously adjusted by using the first moving mechanism according to a change of the image of the sample in a field of view of the interference objective lens, until a first optical axis of the interference objective lens is determined to be substantially perpendicular to a surface of the sample according to the image. The interference objective lens is replaced with the imaging objective lens, and a geometric profile of at least one via of the sample is detected; a second optical axis of the imaging objective lens after replacement overlaps with the first optical axis of the interference objective lens before replacement. 
     Based on the above, in the heterogeneous integration detecting method and the heterogeneous integration detecting apparatus of the disclosure, the optical axis of the imaging objective lens is substantially perpendicular to the surface of the sample, thereby improving the accuracy of detection. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic view of a heterogeneous integration detecting apparatus according to an embodiment of the disclosure. 
         FIG.  2    is a flow chart of a heterogeneous integration detecting method according to an embodiment of the disclosure. 
         FIG.  3    is a schematic view of the heterogeneous integration detecting apparatus of  FIG.  1    in another state. 
         FIG.  4    is a schematic top view of a sample detected by the heterogeneous integration detecting apparatus of  FIG.  1   . 
         FIG.  5    is a schematic view of an optical path of the heterogeneous integration detecting apparatus of  FIG.  1   . 
         FIG.  6    is a schematic cross-sectional view of a portion of the sample of  FIG.  1   . 
         FIG.  7    is a schematic diagram of a spectrum signal obtained by the heterogeneous integration detecting apparatus of  FIG.  1   . 
         FIG.  8    is a low-frequency spectrum analyzed from the spectrum signal of  FIG.  7   . 
         FIG.  9    is a high-frequency spectrum analyzed from the spectrum signal of  FIG.  7   . 
         FIG.  10    is a result of signal processing on the low frequency spectrum of  FIG.  8   . 
         FIG.  11    is a result of signal processing on the high frequency spectrum of  FIG.  9   . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     First of all, heterogeneous integration refers to assembling and packaging a plurality of separately manufactured elements into a single package to improve functions and operating characteristics. 
       FIG.  1    is a schematic view of a heterogeneous integration detecting apparatus according to an embodiment of the disclosure. Referring to  FIG.  1   , a heterogeneous integration detecting apparatus  100  of this embodiment includes a first moving mechanism  110 , an optical system  200 , a sample carrier  120 , and an analyzer  130 . The optical system  200  is installed on the first moving mechanism  110 . The optical system  200  includes an interference objective lens  210  and an imaging objective lens  220 . The sample carrier  120  is used to carry a sample  50 . The analyzer  130  is used to obtain an image output by the optical system  200 . In this embodiment, the optical system  200  is entirely installed on the first moving mechanism  110 , but the disclosure is not limited thereto. 
       FIG.  2    is a flow chart of a heterogeneous integration detecting method according to an embodiment of the disclosure. Referring to  FIG.  1    and  FIG.  2   , first, under the condition of maintaining the same relative distance between the interference objective lens  210  and the sample  50 , the relative posture of the interference objective lens  210  and the sample  50  is continuously adjusted by the first moving mechanism  110  according to the change of an image of the sample  50  in the field of view of the interference objective lens  210 , until a first optical axis  210 A of the interference objective lens  210  is determined to be substantially perpendicular to a surface  52  of the sample  50  according to the image, which is step S 12 . The same relative distance mentioned here means that the distance between the interference objective lens  210  and a center point C 10  of the field of view on the sample  50  is substantially the same. 
     In addition, optionally, in addition to maintaining the same relative distance between the interference objective lens  210  and the sample  50 , the field of view of the interference objective lens  210  may also be maintained to be the same; that is, the range on the sample  50  that may be seen through the interference objective lens  210  is substantially the same. Of course, with the change of the relative posture of the interference objective lens  210  and the sample  50 , the edge of the field of view slightly changes. However, as long as the position of the center point C 10  of the field of view remains the same, the field of view may be regarded as the same. 
     With the adjustment of the relative posture of the interference objective lens  210  and the sample  50 , the image of the sample  50  in the field of view of the interference objective lens  210  also changes. From the changing trend of the image, it may be determined how to adjust the relative posture of the interference objective lens  210  and the sample  50  so that the first optical axis  210 A of the interference objective lens  210  changes toward the trend of the surface  52  that is substantially perpendicular to the sample  50 . Finally, it may be determined from the image that the first optical axis  210 A of the interference objective lens  210  is substantially perpendicular to the surface  52  of the sample  50 , and the adjustment of the relative posture of the interference objective lens  210  and the sample  50  may be stopped at this time. In this embodiment, the determination of the change of the image and the adjustment of the relative posture of the interference objective lens  210  and the sample  50  may be completed through automatic control by a computer running a software. 
       FIG.  3    is a schematic view of the heterogeneous integration detecting apparatus  100  of  FIG.  1    in another state. Referring to  FIG.  2    and  FIG.  3   , the interference objective lens  210  is replaced with the imaging objective lens  220 , and the geometric profile of at least one via  54  (marked in  FIG.  4   ) of the sample  50  is detected, which is step S 14 . A second optical axis  220 A of the imaging objective lens  220  after replacement overlaps with the first optical axis  210 A of the interference objective lens  210  before replacement. Since the second optical axis  220 A of the imaging objective lens  220  after replacement overlaps with the first optical axis  210 A of the interference objective lens  210  before replacement, the second optical axis  220 A of the imaging objective lens  220  after replacement is also substantially perpendicular to the surface  52  of the sample  50 . In this way, it may be ensured that light for detection which passes through the imaging objective lens  220  to be irradiated on the sample  50  is perpendicular to the surface  52  of the sample  50 , so that the depth of the via  54  may be correctly detected. 
     According to the above, in the heterogeneous integration detecting apparatus  100  and the heterogeneous integration detecting method of this embodiment, first, the interference objective lens  210  is used to confirm that the light for detection may be irradiated on the sample  50  in the direction perpendicular to the of the surface  52  of the sample  50 . Next, the interference objective lens  210  is replaced with the imaging objective lens  220  and the geometric profile of at least one via  54  of the sample  50  is detected. Therefore, the sample  50  may be detected non-destructively with high accuracy. 
       FIG.  4    is a schematic top view of the sample  50  detected by the heterogeneous integration detecting apparatus  100  of  FIG.  1   . Referring to  FIG.  1    and  FIG.  4   , in this embodiment, the heterogeneous integration detecting method further includes the following. After the geometric profile of at least one via  54  of the sample  50  is detected, the imaging objective lens  220  is replaced with the interference objective lens  210 , and the sample  50  is moved to change the field of view of the interference objective lens  210 . Next, the previous step is repeated to detect the geometric profile of the via  54  in other regions of the sample  50 . The area of the sample  50  is usually not completely covered by a single field of view of the interference objective lens  210 . For example, in the previous step, the field of view of the interference objective lens  210  and the field of view of the imaging objective lens  220  after replacement correspond to a first detection region R 12  on the sample  50 . After the detection of the geometric profile of the via  54  of the first detection region R 12  on the sample  50  is completed, the geometric profile of a via of a region outside the first detection region R 12  on the sample  50 , for example, the geometric profile of a via of a region R 14 , may be detected to complete the detection of all the regions that need to be detected on the sample  50  in order. In addition to replacing the imaging objective lens  220  with the interference objective lens  210 , it is also necessary to move the sample  50  so that the field of view of the interference objective lens  210  corresponds to the region R 14  on the sample  50 . Next, since the posture of the sample  50  may be changed in the moving process thereof, or a surface of the region R 14  on the sample  50  is not completely parallel to a surface of the first detection region R 12  on the sample  50 , or other factors, step S 12  in  FIG.  2    is repeated to reconfirm that the first optical axis  210 A of the interference objective lens  210  is substantially perpendicular to the surface  52  of the sample  50 . After that, step S 14  in  FIG.  2    is proceeded to to detect the geometric profile of the via  54  of the region R 14  on the sample  50 . 
     In this embodiment, the optical system  200  further includes a second moving mechanism  230  for moving the interference objective lens  210  and the imaging objective lens  220  along the direction perpendicular to the first optical axis  210 A of the interference objective lens  210 . In this way, the possibility of the direction of the first optical axis  210 A of the imaging objective lens  220  after replacement not overlapping with the first optical axis  210 A of the interference objective lens  210  before replacement may be reduced. 
     In this embodiment, the first moving mechanism  110  is a goniometer stage, moving the interference objective lens  210  on a spherical surface whose center of the sphere is the center point C 10  of the field of view of the interference objective lens  210  on the sample  50 . In other words, in the process of the first moving mechanism  110  moving the optical system  200 , the distance between the interference objective lens  210  and the center point C 10  of the sample  50  in the field of view of the interference objective lens  210  remains the same. 
     In this embodiment, the heterogeneous integration detecting apparatus  100  further includes a tri-axial movement mechanism  150 . The sample carrier  120  is installed on the tri-axial movement mechanism  150 . In the process of adjusting the relative posture of the interference objective lens  210  and the sample  50 , if it is found that the distance between the interference objective lens  210  and the center point C 10  of the sample  50  in the field of view of the interference objective lens  210  has changed, the tri-axial movement mechanism  150  may allow the sample carrier  120  to translate along three axes to compensate for the position deviation of the sample  50 . 
       FIG.  5    is a schematic view of an optical path of the heterogeneous integration detecting apparatus  100  of  FIG.  1   . Referring to  FIG.  1    and  FIG.  5   , in this embodiment, the analyzer  130  includes a spectrometer  132  for detecting the geometric profile of at least one via  54  of the sample  50 . An example will be given later to illustrate how the spectrometer  132  detects the geometric profile of at least one via  54  of the sample  50 . In this embodiment, the analyzer  130  further includes an image-capturing element  134 . The image-capturing element  134  obtains an image output by the optical system  200 . Through analyzing this image, it may be determined whether the first optical axis  210 A of the interference objective lens  210  is substantially perpendicular to the surface  52  of the sample  50 . For example, in the process of adjusting the relative posture of the interference objective lens  210  and the sample  50 , the change of the image includes the change in density of interference stripes, the change in the direction of interference stripes, or other changes. Based on such changes, it may be determined how to adjust the relative posture of the interference objective lens  210  and the sample  50  so that the first optical axis  210 A of the interference objective lens  210  changes toward the trend of being substantially perpendicular to the surface  52  of the sample  50 . 
     In this embodiment, the optical system  200  may further include a light source  280 , apertures  242  and  244 , a beam splitter  250 , an aperture mirror  260 , and a mirror  270 . Of course, as long as the functional requirements of the optical system  200  in the foregoing description may be met, the optical system  200  may further include other elements or omit some elements. Light provided by the light source  280  first passes through the aperture  242 , and through the adjustment of the aperture  242 , the range of light irradiated on the surface of the sample  50  may be changed. After the light passes through the aperture  242 , all or part of the light is reflected by the beam splitter  250  and passes through the aperture  244 . The beam splitter  250  may be a semi-transmissive and semi-reflective beam splitter  250  or other types of beam splitter. After passing through the aperture  244 , the light is irradiated on a surface of the sample  50  and is reflected to pass through the aperture  244  again to reach the beam splitter  250 . When the sample  50  reflects light, there may be some stray light, which affects the determination of the geometric profile of the via  54 . Therefore, by appropriately reducing the aperture  244 , stray light may be filtered out, thereby improving the accuracy of the determination of the geometric profile of the via  54 . 
     All or part of the light passing through the aperture  244  and reaching the beam splitter  250  passes through the beam splitter  250  to reach the aperture mirror  260 . The light passing through the aperture at the center of the aperture mirror  260  may reach the spectrometer  132 , and the spectrum measured by the spectrometer  132  may be used to determine the geometric profile of the via  54 . On the other hand, light that does not pass through the aperture at the center of the aperture mirror  260  is reflected to the mirror  270 , and then reflected to the image-capturing element  134  by the mirror  270 . The image-capturing element  134  may be used to display the change in density of interference stripes, the change in the direction of interference stripes, or other changes to determine how to adjust the relative posture of the interference objective lens  210  and the sample  50 . 
       FIG.  6    is a schematic cross-sectional view of a portion of the sample of  FIG.  1   . Referring to  FIG.  1    and  FIG.  6   , the sample  50  of this embodiment includes a substrate  56  and a film layer  58  covering the substrate  56 , and the via  54  passes through the film layer  58  and extends to the substrate  56 . The substrate  56  is, for example, a silicon substrate, and the material of the substrate  56  and the material of the film layer  58  are different, but the disclosure is not limited thereto. In this embodiment, detecting the geometric profile of at least one via  54  of the sample  50  includes detecting the depth of at least one via  54  of the sample  50 . For example, since a plurality of vias  54  are included in the field of view of the imaging objective lens  220 , the average depth of these vias  54  may be measured. In addition, in order to improve accuracy, a plurality of measurements may be performed to obtain an average value of a plurality of measurement data items. 
       FIG.  7    is a schematic diagram of a spectrum signal obtained by the heterogeneous integration detecting apparatus  100  of  FIG.  1   .  FIG.  7    shows a spectrum of light reaching the spectrometer  132 . The lateral axis is the wavelength in nanometers (nm). The vertical axis is the intensity of the light incident on the spectrometer being normalized according to the intensity of the light provided by the light source. It may be seen from  FIG.  7    that the light reaching the spectrometer  132  is mainly a low-frequency curve waveform, and the low-frequency curve waveform is loaded with a high-frequency curve waveform. After the waveform of  FIG.  7    is analyzed, a low-frequency spectrum as shown in  FIG.  8    and a high-frequency spectrum as shown in  FIG.  9    may be obtained. 
     The low-frequency spectrum and the high-frequency spectrum as shown in  FIG.  8    and  FIG.  9    are in a wavelength domain. The low-frequency spectrum and the high-frequency spectrum may be converted to an inverse wavelength domain first, and then the low-frequency spectrum and high-frequency spectrum after conversion may be subjected to fast fourier transform (FFT) to form the waveforms as shown in  FIG.  10    and  FIG.  11   . In  FIG.  10    and  FIG.  11   , the lateral axis is the length in micrometers (μm), and the vertical axis is the intensity of the light incident on the spectrometer being standardized according to the intensity of the light provided by the light source. In  FIG.  10   , the position with the maximum intensity has a value of 0.422 micrometers on the lateral axis, from which it may be determined that the thickness of the film layer  58  is 0.422 micrometers. In  FIG.  11   , the position with the maximum intensity has a value of 32.43 micrometers on the lateral axis, from which it may be determined that the depth of the via  54  is 32.43 micrometers. The above examples illustrate how the geometric profile of the via  54  is determined in the embodiment, but the disclosure is not limited thereto. 
     In summary, in the heterogeneous integration detecting method and the heterogeneous integration detecting apparatus in the disclosure, the interference objective lens is first used to confirm that the optical axis is substantially perpendicular to the surface of the sample, and then the imaging objective lens is used to perform detection, which may improve the accuracy of the detection.