A measuring device for fast scanning microstructure height

Abstract

The utility model discloses a kind of for the measurement device of quick scanning microstructure height, belong to microstructure three-dimensional topography measurement technical field.The device includes linear spectrum confocal point sensor array, linear light form light source, displacement platform and processing unit.The linear spectrum confocal point sensor array is composed of multiple spectrum confocal point sensor units along straight line arrangement, its innovation point is, the spacing between the spectrum confocal point sensor unit is adjustable, to be able to according to the measurement requirement of different regions (such as chip area and cutting path area on wafer) of measured sample surface, flexible configuration scanning density.The utility model is by line scanning mode, in combination with variable scanning point distribution, while guaranteeing key area measurement accuracy, substantially improve overall scanning efficiency, especially suitable for efficient coplanar detection of wafer bump in semiconductor advanced packaging.

Description

Technical Field

[0001] This utility model relates to the field of three-dimensional morphology measurement technology of microstructures, and in particular to a measurement device for rapidly scanning the height of microstructures. Background Technology

[0002] In advanced packaging processes, especially wafer-to-wafer bonding and die-to-wafer bonding, it is typically necessary to perform coplanarity testing on the bumps on the wafer surface before bonding to ensure bonding quality and yield. Uneven bump height distribution directly affects the success rate of subsequent bonding processes and can even lead to product failure. Currently, commonly used measurement methods include optical measurement methods such as white light interferometers. While these methods offer high accuracy, they require data acquisition point-by-point or area-by-area when scanning the entire sample surface, which is time-consuming and difficult to meet the demands of high-efficiency production cycles.

[0003] Spectral confocal measurement is another widely used method for measuring the height of microstructures. Its basic principle is that a white light source is decomposed into a continuous spectrum by a dispersive element (such as a grating or prism). Light of different wavelengths is focused at different axial positions (Z-axis), forming a "spectral-depth" correspondence. By receiving the reflected light from the surface of the object being measured and analyzing its peak wavelength with a spectrometer, accurate calculation of displacement or thickness can be achieved. However, existing spectral confocal sensors mostly use single-point or small-area scanning methods, which have limited efficiency when measuring large-area samples, and there is still no mature solution for flexibly configuring the scanning point spacing to optimize measurement efficiency.

[0004] Furthermore, in applications such as chip-wafer bonding, the area being measured typically includes the chip area and the dicing area. The former requires high-density scanning, while the latter does not require the same level of precision. Existing equipment has failed to effectively balance the distribution of scanning points with measurement efficiency, resulting in an overall measurement time that remains relatively long.

[0005] Therefore, it is necessary to develop a microstructure height measurement device that can achieve rapid, efficient, and flexible adjustment of the scanning point spacing to improve detection speed and process yield. Utility Model Content

[0006] To address this issue, this invention provides a measurement device for rapidly scanning the height of microstructures. This device solves the problem that in the prior art, when using measurement methods such as white light interferometers to detect coplanar bumps on a wafer surface, the overall scanning time is too long, and the distribution of scanning points cannot be flexibly adjusted according to the importance of the sample area to optimize efficiency.

[0007] To solve the above-mentioned technical problems, this utility model provides a measurement device for rapidly scanning the height of microstructures, comprising:

[0008] A linear spectral confocal sensor array, the linear spectral confocal sensor array comprising a plurality of spectral confocal sensor units arranged along a first direction;

[0009] A linear light source is used to project a strip of light onto the surface of the sample being tested;

[0010] A displacement platform is provided for supporting the sample under test or the measuring device, and for enabling the two to move relative to each other along a second direction perpendicular to the first direction.

[0011] A processing unit, connected to the linear spectral confocal sensor array, is used to calculate height data based on the reflected light information collected by each of the spectral confocal sensor units.

[0012] In one embodiment of the present invention, the spacing between at least two of the linear spectral confocal sensor units in the linear spectral confocal sensor array is adjustable.

[0013] In one embodiment of this utility model, the linear spectral confocal sensor array is configured to adjust the spacing of the spectral confocal sensor units in the corresponding regions according to the preset measurement density of different regions on the surface of the sample being measured.

[0014] In one embodiment of the present invention, the linear spectral confocal sensor array is configured to use a first spacing when scanning the chip region on the wafer, and a second spacing greater than the first spacing when scanning the dicing region on the wafer.

[0015] In one embodiment of this utility model, the outgoing optical path of the linear light source and the receiving optical path of the linear spectral confocal sensor array are integrated in the same optical module.

[0016] In one embodiment of the present invention, the processing unit is further configured to: stitch together and fuse the height data obtained from multiple scans to generate an overall three-dimensional topographic map of the surface of the sample under test.

[0017] In one embodiment of this utility model, the processing unit optimizes the splicing and fusion algorithm to seamlessly splice the data obtained from multiple scans at the edge of the splicing area.

[0018] In one embodiment of this utility model, the displacement platform is a precision linear motor platform or a ball screw platform.

[0019] In one embodiment of this utility model, the plurality of spectral confocal sensor units are fixed by an adjustable mounting plate to achieve spacing adjustment.

[0020] In one embodiment of the present invention, the device further includes a bracket for mounting the linear spectral confocal sensor array and the linear light source, the bracket being disposed above the guide rail of the displacement platform.

[0021] The above-mentioned technical solution of this utility model has the following advantages compared with the prior art:

[0022] The measurement device for rapidly scanning the height of microstructures described in this invention employs an adjustable-spacing linear spectral confocal sensor array in conjunction with a linear light source for line scanning. This allows for flexible configuration of the scanning density based on the importance of the sample area, thereby significantly improving overall scanning efficiency while ensuring measurement accuracy in critical areas. It effectively solves the problem of balancing measurement efficiency and accuracy in existing technologies, reduces the risk of bonding failure due to poor bump coplanarity, and improves the yield of advanced packaging processes. Attached Figure Description

[0023] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0024] Figure 1 This invention relates to a measurement device for rapidly scanning the height of microstructures, wherein (a) is a measurement device with equal spacing between adjacent spectral confocal sensor units, and (b) is a measurement device with different spacing between adjacent spectral confocal sensor units.

[0025] Explanation of reference numerals in the accompanying drawings: 1. Linear spectral confocal sensor array; 2. Linear light source. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention.

[0027] Example 1:

[0028] like Figure 1 As shown, the present invention provides a measurement device for rapidly scanning the height of microstructures, which mainly includes a linear spectral confocal sensor array 1, a linear light source 2, a displacement platform, and a processing unit.

[0029] The linear spectral confocal sensor array 1 consists of multiple independent spectral confocal sensor units arranged along a straight line. Each spectral confocal sensor unit includes a dispersive lens and a miniature spectrometer (not shown separately in the figure). Light emitted from the white light source forms a continuous focal point distributed axially after passing through the dispersive lens. Light reflected from the surface of the sample is collected by the same lens and transmitted to the miniature spectrometer for analysis. The precise distance (height) from the spectral confocal sensor unit to the surface of the sample is determined by identifying the peak wavelength of the reflected spectrum.

[0030] The linear light source 2 uses optical elements such as cylindrical mirrors to shape the light emitted by the light source (such as LED or halogen lamp) into a strip-shaped light spot that matches the length direction of the sensor array 1, and projects it onto the surface of the sample being tested, providing uniform illumination for the entire measurement area of ​​the linear array.

[0031] The displacement platform is a precision linear motor platform in this embodiment, used to carry and drive the sample under test (such as a wafer) to move precisely and uniformly along the Y-axis direction (i.e., the direction perpendicular to the X-axis, the extension direction of the linear spectral confocal sensor array 1). It can be understood that in other embodiments, the displacement platform may remain stationary while driving the support carrying the linear spectral confocal sensor array 1 and the linear light source 2 to move.

[0032] The processing unit, such as an industrial computer or embedded system, is signal-connected to each spectral confocal sensor unit in the linear spectral confocal sensor array 1 via a data cable. The processing unit receives spectral data collected by each spectral confocal sensor unit in real time, calculates the height information of the corresponding point, and synchronously records the position coordinates of the sample on the displacement platform at that moment (achieved through synchronization with the encoder signal of the displacement platform). Finally, the processing unit combines all the collected height data with the position coordinates to generate three-dimensional topographic point cloud data of the surface of the sample under test.

[0033] In this embodiment, the linear spectral confocal sensor array 1 and the linear light source 2 are integrated together by a rigid bracket to form a compact measuring head, which is fixed above the displacement platform to ensure optical path stability.

[0034] Workflow: During measurement, the sample is placed on a displacement platform. A linear light source 2 illuminates a line on the sample surface (along the X direction). Multiple confocal spectral sensor units on the linear spectral confocal sensor array 1 simultaneously measure the height of the corresponding point on this illumination line. Subsequently, the displacement platform moves the sample a small distance, either stepping or moving at a constant speed, and the linear spectral confocal sensor array 1 performs another measurement. This "line scan" method quickly covers the entire measurement area. The processing unit stitches together all these line scan data to ultimately form a complete three-dimensional surface topography.

[0035] Example 2:

[0036] Based on Example 1, this embodiment further optimizes the adjustability of the spacing between the spectral confocal sensor units to better adapt to the different measurement density requirements of die and scribe line in wafer inspection.

[0037] The multiple spectral confocal sensor units 1 in the linear spectral confocal sensor array 1 are not fixedly installed, but are secured by an adjustable mounting plate. This mounting plate has multiple sliding grooves, and each spectral confocal sensor unit is mounted on a corresponding slider using fasteners (such as screws). The sliders can slide along the grooves, thereby changing the spacing d between adjacent spectral confocal sensor units. After adjustment, tightening the fasteners locks the position of the spectral confocal sensor units in place.

[0038] In practical applications: For the chip area on the wafer, high-density measurement is required to ensure that each bump is accurately captured. Therefore, the spacing d1 of the corresponding spectral confocal sensor units is adjusted to be smaller. For the diced area, which does not require high-density measurement, the spacing d2 of the corresponding spectral confocal sensor units is adjusted to be larger (d2>d1). With this configuration, the effective width covered by a single line scan increases while keeping the total number of spectral confocal sensor units constant. This significantly reduces the travel distance and total time required to scan the entire sample while maintaining measurement accuracy in critical areas.

[0039] Example 3:

[0040] This embodiment focuses on the optimization of data processing and splicing.

[0041] Based on Embodiment 1 or 2, the processing unit pre-stores an optimized stitching and fusion algorithm. After scanning the entire sample, the processing unit processes the overlapping area data generated by multiple line scans. This algorithm effectively eliminates "steps" or gaps that may be caused by sensor errors or environmental vibrations at the stitching edges by performing weighted averaging and surface fitting on the height data of the overlapping areas, achieving seamless and smooth stitching of the three-dimensional topography data and generating a high-fidelity overall three-dimensional topography map.

[0042] Furthermore, a high-precision ball screw platform can be used instead of a linear motor platform for the displacement platform. The output optical path of the linear light source 2 and the receiving optical path of the linear spectrum confocal sensor array 1 can be further integrated into the same optical module housing through coaxial optical design to reduce the overall size and improve system stability.

[0043] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A measuring device for rapidly scanning the height of microstructures, characterized in that, include: A linear spectral confocal sensor array, the linear spectral confocal sensor array comprising a plurality of spectral confocal sensor units arranged along a first direction; A linear light source is used to project a strip of light onto the surface of the sample being tested; A displacement platform is provided for supporting the sample under test or the measuring device, and for enabling the two to move relative to each other along a second direction perpendicular to the first direction. A processing unit, connected to the linear spectral confocal sensor array, is used to calculate height data based on the reflected light information collected by each of the spectral confocal sensor units.

2. The measuring device for rapidly scanning the height of microstructures according to claim 1, characterized in that, In the linear spectral confocal sensor array, the spacing between at least two of the spectral confocal sensor units is adjustable.

3. The measuring device for rapidly scanning the height of microstructures according to claim 2, characterized in that, The linear spectral confocal sensor array is configured to adjust the spacing of the spectral confocal sensor units in the corresponding regions according to the preset measurement density of different regions on the surface of the sample being measured.

4. The measuring device for rapidly scanning the height of microstructures according to claim 3, characterized in that, The linear spectral confocal sensor array is configured to use a first spacing when scanning the chip region on the wafer, and a second spacing greater than the first spacing when scanning the dicing region on the wafer.

5. The measuring device for rapidly scanning the height of microstructures according to claim 1, characterized in that, The outgoing optical path of the linear light source and the receiving optical path of the linear spectral confocal sensor array are integrated in the same optical module.

6. The measuring device for rapidly scanning the height of microstructures according to claim 1, characterized in that, The processing unit is further configured to stitch together the height data obtained from multiple scans to generate an overall three-dimensional topographic map of the surface of the sample under test.

7. The measuring device for rapidly scanning the height of microstructures according to claim 1, characterized in that, The processing unit optimizes the stitching and fusion algorithm to seamlessly stitch together the data obtained from multiple scans at the edge of the stitching area.

8. The measuring device for rapidly scanning the height of microstructures according to claim 1, characterized in that, The displacement platform is a precision linear motor platform or a ball screw platform.

9. The measuring device for rapidly scanning the height of microstructures according to claim 1, characterized in that, The multiple spectral confocal sensor units are fixed by an adjustable mounting plate to allow for spacing adjustment.

10. The measuring device for rapidly scanning the height of microstructures according to claim 1, characterized in that, The device also includes a bracket for mounting the linear spectral confocal sensor array and the linear light source, the bracket being disposed above the guide rail of the displacement platform.

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