JP3945638B2 - Inspection method and inspection apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inspection method and an inspection apparatus, and more particularly to an inspection method and an inspection apparatus for inspecting a semiconductor wafer on which bumps are mounted.
[0002]
In recent years, in semiconductor devices, a method of connecting a semiconductor chip and a mounting substrate through bumps which are bonding electrodes has been adopted. At that time, irregularities such as bump shapes, heights, dimensions, positions, etc. and foreign matters such as dust and bump residue on the bump mounting surface are one of the causes of defective bonding between the semiconductor chip and the mounting substrate. For this reason, it is required not only to perform various measurements and inspections related to bumps, but also to inspect semiconductor wafers on which bumps are mounted efficiently in a short time.
[0003]
[Prior art]
Conventionally, an inspection apparatus for measuring and inspecting bumps generally includes a two-dimensional measurement / inspection apparatus and a three-dimensional measurement / inspection apparatus (hereinafter referred to as a two-dimensional system apparatus or a three-dimensional system apparatus) at positions where they do not interfere with each other. is set up.
[0004]
The two-dimensional system device includes a CCD camera above a semiconductor wafer that is sucked and fixed to a stage, and performs bump size measurement and positional deviation inspection based on image data of the bumps captured by the CCD camera. On the other hand, the three-dimensional system apparatus includes a laser and an acousto-optic deflector (AOD) disposed obliquely above the semiconductor wafer, and a position detector (PSD) disposed obliquely above the semiconductor wafer that is symmetrical to the laser. The height of the bump is measured by using a triangulation method. Specifically, the three-dimensional system apparatus deflects laser light emitted from a laser with an AOD and irradiates the bumps obliquely from above, and reflects the reflected light from the bump apex and the reflected light from the wafer surface in the vicinity of the bump. Light is received by PSD. Then, the three-dimensional system apparatus measures the height of the bump by detecting the difference between the reflected light from the bump apex received by the PSD and the reflected light from the wafer surface.
[0005]
The inspection apparatus performs measurement / inspection processing by such a two-dimensional apparatus and a three-dimensional apparatus simultaneously and in parallel. Thus, conventionally, it is possible to perform bump height measurement in one process in addition to bump dimension measurement and positional deviation inspection.
[0006]
[Problems to be solved by the invention]
By the way, conventionally, inspection for detecting foreign matters such as dust and bump residue on a wafer is performed by using an apparatus different from the above-described inspection apparatus, for example, a CCD camera for patterning inspection for inspecting a pattern formed on a wafer. It is performed in a separate inspection process that differs from bump size / height measurement and misalignment inspection. That is, a conventional two-dimensional system apparatus that uses bumps for measurement / inspection cannot detect foreign matter present on the wafer.
[0007]
As a result, there is a problem that the equipment cost of the inspection apparatus increases. Further, since the foreign object detection inspection is separately performed for the bump measurement / inspection, there is a problem that the entire inspection time is increased as a result. For this reason, when other inspection items are added in the conventional inspection apparatus, it is necessary to use an apparatus suitable for the inspection, which increases inspection costs and efficiently performs various inspections. I could not.
[0008]
The present invention has been made to solve the above problems, and an object of the present invention is to provide an inspection method and an inspection apparatus capable of efficiently performing a plurality of measurement / inspection items.
[0009]
[Means for Solving the Problems]
  In order to achieve the above object, according to the first aspect of the present invention, an inspection apparatus irradiates a semiconductor wafer with measurement light having a predetermined intensity and scans the semiconductor wafer with the measurement light, and the semiconductor wafer. A detection device for detecting reflected light from the semiconductor wafer and reflected light from a bump formed on the semiconductor wafer, and an imaging device for imaging a predetermined area of the semiconductor wafer, and measuring bump height, measuring dimensions, and detecting misalignment , Bridge inspection, missing inspection and foreign matter detection inspectionDo at least one of
Binarizing the image data from the imaging device, determining whether the center of gravity position of the blob extracted by the binarization processing matches the center position of the bump at the theoretical coordinate position, The bump size is measured for the matching blob. in this way,Multiple inspection items can be efficiently performed without adding a separate inspection device.In addition, it is possible to measure the bump dimensions with high accuracy and efficiency.The
[0010]
  According to invention of Claim 2,A scanning device that irradiates a semiconductor wafer with measurement light of a predetermined intensity and scans the measurement light on the semiconductor wafer, and detection that detects reflected light from the semiconductor wafer and reflected light from bumps formed on the semiconductor wafer And a bump height measurement based on image data from the imaging device, and a bump height measurement based on reflected light detected by the detection device. In addition to the dimension measurement and the positional deviation inspection, at least one of a bridge inspection, a missing inspection, and a foreign matter detection inspection is performed. In the positional deviation inspection, the semiconductor wafer is divided into a matrix and divided into a plurality of statistical areas, The difference between the average value of the positional deviation values calculated for each statistical area and the individual positional deviation values is calculated.in this way,A plurality of inspection items can be efficiently performed without adding a separate inspection apparatus, and the positional error inspection can be performed with high accuracy by reducing the influence of mechanical errors.
[0011]
  According to invention of Claim 3,In the misalignment inspection, the semiconductor wafer is divided into two or more regions around the rotation axis of the stage that holds the semiconductor wafer by suction, and the position is determined according to an error correction value in the θ direction of the stage calculated in each region. The deviation value was corrected.ThisMisalignment inspection can be performed with higher accuracy.
[0012]
  According to invention of Claim 4,The image data is taken in during the constant speed movement of the stage for attracting and fixing the semiconductor wafer, and the misalignment inspection and the foreign matter detection inspection are performed during the acceleration / deceleration period of the stage.ThisFurthermore, it is possible to perform measurement / inspection processing more efficiently.
[0013]
  According to the invention of claim 5,A scanning device that irradiates a semiconductor wafer with measurement light of a predetermined intensity and scans the measurement light on the semiconductor wafer, and detection that detects reflected light from the semiconductor wafer and reflected light from bumps formed on the semiconductor wafer An inspection apparatus for inspecting bumps formed on the semiconductor wafer, the apparatus including an apparatus and an imaging apparatus for imaging a predetermined area of the semiconductor wafer, wherein the dimensions of the bumps are determined based on image data from the imaging apparatus In addition to measurement and misalignment inspection, at least one of bridge inspection, missing inspection, and foreign object detection inspection is performed, the image data from the imaging device is binarized, and the center of gravity position of the blob extracted by the binarization processing And whether or not the center position of the bump at the theoretical coordinate position matches, and measure the size of the bump for the matching blob Equipped with a control device. In this apparatus, a plurality of inspection items can be efficiently performed without adding a separate inspection apparatus, and bump dimension measurement can be performed with high accuracy and efficiency.
[0014]
  According to the invention of claim 6,A scanning device that irradiates a semiconductor wafer with measurement light of a predetermined intensity and scans the measurement light on the semiconductor wafer, and detection that detects reflected light from the semiconductor wafer and reflected light from bumps formed on the semiconductor wafer An inspection apparatus for inspecting bumps formed on the semiconductor wafer, the apparatus including an apparatus and an imaging apparatus for imaging a predetermined area of the semiconductor wafer, wherein the dimensions of the bumps are determined based on image data from the imaging apparatus In addition to measurement and misalignment inspection, at least one of bridge inspection, missing inspection, and foreign matter detection inspection is performed. In the misalignment inspection, the semiconductor wafer is partitioned into a plurality of statistical regions and divided into a plurality of statistical regions. A control device is provided that calculates the difference between the average value of the positional deviation values calculated for each and the individual positional deviation values. In this apparatus, it is possible to efficiently perform a plurality of inspection items without adding a separate inspection apparatus, and it is possible to accurately perform a positional deviation inspection by reducing the influence of mechanical errors.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
FIG. 1 is a schematic diagram showing a measurement optical system of a bump inspection apparatus.
[0016]
The bump inspection apparatus 11 includes an XYZθ stage (hereinafter referred to as a stage) 12 for attracting and fixing a semiconductor wafer W on which bumps are formed, and an imaging apparatus 13 disposed above the wafer W placed on the stage 12. And a scanning device 14 and a detection device 15 disposed obliquely above the wafer W. The scanning device 14 and the detection device 15 are arranged at positions that are targets of each other.
[0017]
The stage 12 is provided so as to be movable in the X, Y, and Z directions and rotatable in the θ direction (not shown) by a drive mechanism (not shown). Further, in this stage 12, the arrangement positions of the imaging device 13, the scanning device 14 and the detection device 15 with respect to the wafer W attracted and fixed to the stage 12 are corrected, and the imaging position of the wafer W by the imaging device 13 is adjusted. A recognition mark AM is installed for this purpose.
[0018]
The imaging device 13 includes a light source 16, a CCD 17, and an optical filter 18. More specifically, the light emitted from the light source 16 is substantially collimated by a lens (collimator lens or the like) (not shown), and a part thereof is refracted by 90 degrees by a light-transmitting half mirror 19 and is not shown. The wafer W is irradiated through the objective lens. The reflected light from the wafer W is substantially collimated through the objective lens, and a part of the reflected light passes through the half mirror 19 and is then enlarged and imaged on the CCD 17 through an imaging lens (not shown). The optical filter 18 is a filter for blocking light of a specific wavelength, and prevents laser light from the scanning device 14 described later from being reflected on the CCD 17.
[0019]
The scanning device 14 includes a laser 20 and an acousto-optical deflector (hereinafter referred to as AOD) 21, and the detection device 15 includes a position detector (hereinafter referred to as PSD) 22. More specifically, the laser light (parallel light flux) emitted from the laser 20 is deflected by the AOD 21 in the X direction in the drawing with a predetermined scanning width, and is irradiated onto the wafer W through a lens (not shown). The laser light irradiated on the wafer W obliquely from above is reflected by the surface of the wafer W at the apex of the bump and in the vicinity thereof, and the reflected light is received by the PSD 22 through a lens (not shown).
[0020]
The bump inspection apparatus 11 configured as described above captures a two-dimensional image of the wafer W by the imaging apparatus 13, and performs a two-dimensional inspection on each bump and the surface of the wafer W based on the image data. In the present embodiment, the two-dimensional inspection includes bump size measurement, misalignment inspection, inspection of whether the bump is short-circuited (bridge inspection), and inspection of whether all the bumps are formed. (Missing inspection) and foreign matter detection inspection such as dust and bump residue on the surface of the wafer W are included. The bump inspection apparatus 11 performs a three-dimensional inspection on the bumps based on the bump apex received by the PSD 22 and the reflected light from the surface of the wafer W. In the present embodiment, the three-dimensional inspection includes bump height measurement, and the flatness (coplanarity) between the bumps is inspected based on the measurement result.
[0021]
FIG. 2 is a block diagram showing a circuit configuration of the bump inspection apparatus.
The bump inspection apparatus 11 includes a console 23 serving as a control terminal and first to third control apparatuses 24 to 26 that generate control data corresponding to various inspections based on instructions from the user input to the console 23. With. Specifically, the first control device 24 outputs control data corresponding to an instruction from the console 23 to the second and third control devices 25 and 26. The second control device 25 drives and controls the stage 12, the AOD 21 and the PSD 22 in response to the control data output from the first control device 24. Further, the third control device 26 drives and controls the CCD 17 in response to control data output from the first control device 24.
[0022]
Hereinafter, the configuration of the first to third control devices 24 to 26 will be described in detail with reference to FIGS.
FIG. 3 is a block diagram of the first control device 24.
The first control device 24 includes a user interface 31, a data memory 32, and a data communication unit 33.
[0023]
The user interface 31 includes a function for creating control data based on an instruction from the user input via the console 23, a function for displaying various inspection results, and the like. The data memory 32 includes product type data 34 storing alignment information, wafer information, bump type, and the like, and measurement result data 35 storing results of respective measurements / inspections in second and third control devices 25 and 26 described later. Stored.
[0024]
Such a first control device 24 extracts the product data 34 of the wafer W to be inspected from the data memory 32 based on the control data from the user interface 31, and sends it from the data communication unit 33 to the second and third data. The data is transmitted to the control devices 25 and 26. Further, the first control device 24 receives the measurement results from the second and third control devices 25 and 26 by the data communication unit 33 and stores them in the data memory 32.
[0025]
FIG. 4 is a block diagram of the second control device 25.
The second control device 25 includes a height calculation circuit 41, a height memory 42, an AOD drive circuit 43, a stage drive circuit 44, an address calculation circuit 45, a measurement unit 46, and a data communication unit 47.
[0026]
The height calculation circuit 41 calculates the height of the light spot irradiated to the bumps of the wafer W based on the current values I1 and I2 input from both electrodes of the PSD 22, and obtains height data H obtained by digitizing the height. Store in the memory 42. The AOD drive circuit 43 drives the AOD 21 and outputs scanning position information included in the drive signal to the address calculation circuit 45. The stage drive circuit 44 drives the stage 12, detects position information of the stage 12 driven thereby, and outputs it to the address calculation circuit 45. The address calculation circuit 45 designates the storage address of the height data H stored in the height memory 42 based on the position information output from the AOD drive circuit 43 and the stage drive circuit 44, respectively. The measuring unit 46 extracts the height data H from the height memory 42 based on the storage address, and measures the bump height based on the height data H. The measurement unit 46 receives height data H from the height calculation circuit 41 as necessary, and drives and controls the AOD drive circuit 43 and the stage drive circuit 44 according to the height data H.
[0027]
Such a second control device 25 transmits the bump height (that is, the measurement result data 35 shown in FIG. 3) measured by the measurement unit 46 to the first control device 24 via the data communication unit 47. Further, the second control device 25 transmits the product type data 34 received from the first control device 24 to the third control device 26 via the data communication unit 47.
[0028]
FIG. 5 is a block diagram of the third control device 26.
The third control device 26 includes an image input circuit 51, first and second frame memories 52 and 53 (frame memories 1 and 2 in the figure), a parameter memory 54, a measurement unit 55, and a data communication unit 56.
[0029]
The image input circuit 51 amplifies the output signal from the CCD 17 and separates it into a video signal and a synchronization signal, and digitizes the video signal to generate image data alternately in the first frame memory 52 or the second frame memory 53. Store. The image input circuit 51 calculates a storage address of the first frame memory 52 or the second frame memory 53 in which image data is stored based on the synchronization signal. The parameter memory 54 stores the product data 34 received by the data communication unit 56 via the data communication units 33 and 47 of the first and second control devices 24 and 25. The measurement unit 55 refers to the product type data 34 and performs various measurement processes and statistical processes to be described later based on the image data stored in the first frame memory 52 or the second frame memory 53.
[0030]
Such a third control device 26 sends the results of measurement processing and statistical processing (that is, measurement result data 35 shown in FIG. 3) executed by the measurement unit 55 from the data communication unit 56 to the second control device 25 (data communication). To the first control device 24 (data communication unit 33) via the unit 47).
[0031]
FIG. 6 is an explanatory diagram of the recognition mark AM installed on the stage 12.
Usually, the recognition mark AM is formed on the silicon substrate in a predetermined pattern shape made of aluminum, and in this embodiment, the recognition mark AM is composed of first to sixth mark regions AM1 to AM6 having different pattern shapes. Yes. Each of the mark areas AM1 to AM6 is formed in the same area as the imaging range by the CCD 17.
[0032]
In such a recognition mark AM, the arrangement positions of the CCD 17, the AOD 21 and the PSD 22 are adjusted, for example, by moving the stage 12 using an isolated point pattern formed in the first mark area AM1. The adjustment of the focal position (scanning direction) of the laser beam by the AOD 21 is performed by moving the stage 12 using, for example, a stripe pattern formed in the third to sixth mark areas AM3 to AM6.
[0033]
Hereinafter, as an example of the position adjustment using the isolated point pattern P formed in the first mark area AM1, the case of adjusting the imaging position by the CCD 17 will be described in detail.
[0034]
As shown in FIG. 7, in the first mark area AM1, the isolated point pattern P is formed at the center of the laser scanning width by the AOD 21 (indicated by (x2-x1) in the figure). The AOD 21 scans the isolated point pattern P with laser light, and the PSD 22 detects the brightness B1 of the reflected light from the isolated point pattern P at that time. Then, the position of the stage 12 is adjusted so that the rise and fall of the luminance B1 detected by the PSD 22 are at the center position of the laser scanning width. Thereby, the imaging position of the CCD 17 in the laser scanning direction is adjusted.
[0035]
In addition, the AOD 21 scans the isolated point pattern P with laser light, and in that state, moves the stage 12 in a direction orthogonal to the laser scanning direction. The PSD 22 detects the brightness B2 of the reflected light from the isolated point pattern P at that time. Then, the position of the stage 12 is adjusted so that the rise and fall of the luminance B2 detected by the PSD 22 become the center position (indicated by x3 in the figure) of the image in the direction orthogonal to the laser scanning direction. Thereby, the imaging position of the CCD 17 in the direction orthogonal to the laser scanning direction is adjusted.
[0036]
Next, the two-dimensional inspection process of the bump inspection apparatus 11 will be described in detail.
FIG. 8 is a flowchart showing the processing of the two-dimensional measurement system.
In the second controller 25, when the measuring unit 46 receives the product data 34 (step 61), the stage drive circuit is based on positioning image data (data developed in the parameter memory 54) registered in advance for each product. 44 is driven to adjust the position of the attracted wafer W on the stage 12 (step 62). Thereby, the imaging position by AOD21 and CCD17 is adjusted.
[0037]
In the third control device 26, the data communication unit 56 receives area data storing information such as the number of images captured by the CCD 17 and the number of bumps formed on the wafer W (step 63). Store in the memory 54.
[0038]
Assume that the number of images captured by the CCD 17 set in the area data is n. First, the image input circuit 51 captures the first image data imaged by the CCD 17 (step 64), and stores the captured image data in the first frame memory 52.
[0039]
The measurement unit 55 performs predetermined measurement / inspection processing (dimension measurement, bridge inspection, missing inspection) based on the image data stored in the first frame memory 52 (step 65a). Then, during the measurement / inspection process in step 65a, the image input circuit 51 takes in the second image data picked up by the CCD 17 and stores it in the second frame memory 53 (step 65b).
[0040]
The measurement unit 55 has performed image data measurement / inspection processing (n−1) times, that is, stored in the first frame memory 52 or the second frame memory 53 out of n images taken by the CCD 17. (N-1) It is determined whether or not measurement / inspection processing has been performed on the image data of the first sheet (step 66). At this time, if not finished yet, until the n-th image data is taken into the first frame memory 52 or the second frame memory 53, in other words, the measuring unit 55 performs the (n-1) -th image. Steps 65 and 66 are repeated until the measurement / inspection processing for data is completed.
[0041]
Then, when the n-th image data is captured, the measurement unit 55 performs measurement / inspection processing for the n-th image data (step 67), and then performs area statistical processing (position shift inspection, foreign object detection inspection). (Step 68).
[0042]
When the area statistical processing is completed, the measurement unit 55 transmits the measurement result data by the area statistical processing and the measurement result data by the measurement / inspection processing from the data communication unit 56 to the second control device 25 (specifically, the data communication unit). 47) (step 69). Thereafter, the measuring unit 55 determines whether or not there is area data for the next candidate (step 70). If it exists at this time, the above step 63 is continued until there is no area data for the next candidate in step 70. Repeat ~ 70 again.
[0043]
FIG. 9 is a flowchart showing the measurement process per screen, and specifically shows the process in step 65a or step 67 in FIG. It is assumed that the number of bumps formed at the theoretical coordinate position included in the image data per screen is N.
[0044]
First, the measurement unit 55 performs binarization blob processing on the entire captured image data (one screen) (step 71).
The binarized blob process will be described in detail. In the image data picked up by the CCD 17, each bump formed on the wafer W is copied in black because it does not reflect light in the vertical direction of the wafer W. In particular, at this time, the edge of the bump becomes a place where the density difference of the pixel is the largest compared with the surrounding area (the surface of the wafer W). Therefore, each bump is represented as a black block (blob) with respect to the surface of the wafer W. As a result, the entire screen of the grayscale image displayed with 256 gradations for each pixel is binarized into white / black. The slice level for binarizing the gray scale image into white / black is set and stored for each type of wafer W.
[0045]
Now, for the binarized image, a blob whose black area is about ± 50% of the bump area (expected value) is extracted, and the number of the blob is M. And
[0046]
Here, with respect to the extracted M blobs, their center of gravity positions are detected, and the center of gravity position of the blob m (0, 1,... M) at a predetermined location is within a minute error with respect to the theoretical coordinate position of the bump. Extracts the blob m as a bump n (0, 1,... N).
[0047]
Specifically, the measurement unit 55 first determines whether or not the coordinate values of the blob m (m = 0; initial value) and the bump n (n = 0; initial value) match (steps 72 to 74). At this time, if the coordinate values match each other, the measurement unit 55 determines that the blob is a bump and performs dimension measurement (step 75). Conversely, if they do not match, the measuring unit 55 determines whether or not “n = N” (step 76).
[0048]
At this time, if “n = N”, the measurement unit 55 determines that the blob is not a bump, and stores the coordinate value using the blob as an extra (step 77). Incidentally, the extra for storing the coordinate values here includes, for example, dust on the wafer W, foreign matter such as bump residue, or a blob having the possibility of a bump bridge state and a missing state. That is, the foreign object detection inspection, the bridge inspection, and the missing inspection are performed based on the blob stored as an extra at this time. On the other hand, when “n ≠ N”, the measurement unit 55 counts up the value of the bump n, and determines whether the coordinate value of the counted bump n and the blob m match in the same manner as described above. (Steps 72 to 74).
[0049]
On the other hand, in step 75, when the dimension measurement is completed, the measurement unit 55 increments the value of the dimension measurement count c (c = 0; initial value) and determines whether or not “c = n”. (Step 78).
[0050]
At this time, when “c ≠ n”, the measurement unit 55 counts up the value of the blob m, and determines whether or not the value of the blob m counted up and the coordinate value of the bump n coincide with each other. (Steps 72 to 74). Conversely, when “c = n”, the measurement unit 55 determines whether or not “m = M” (step 79).
[0051]
At this time, if “m = M”, the measurement unit 55 ends the measurement process for the image data per screen. That is, one measurement process is terminated in step 65a shown in FIG. On the other hand, if “m ≠ M”, the measurement unit 55 determines that the blob is not a bump, and stores the coordinate value as an extra in the same manner as described above (step 77).
[0052]
When storing the extra, the measurement unit 55 counts up the number of times of storage e (e = 0; initial value), and whether or not “m = M” or “c = N”. Is determined (step 80).
[0053]
At this time, if “m = M” or “c = N”, the measurement unit 55 ends the measurement process for the image data per screen. On the other hand, if “m ≠ M” and “c ≠ N”, the value of blob m is counted up, and whether the value of blob m counted up and the coordinate value of bump n match each other. Is determined in the same manner as described above (steps 72 to 74).
[0054]
Next, image capture by the bump inspection apparatus 11 will be described in detail.
FIG. 10 is a timing chart of image capture.
In the two-dimensional inspection, first, the first image data picked up by the CCD 17 is captured at the timing t1, and is stored in the first frame memory 52 as a first image buffer (image buffer 1 in the figure). Stored.
[0055]
Next, at timing t2, measurement / inspection processing of the first image data stored in the first frame memory 52 is performed. During the measurement / inspection process, the second image data picked up by the CCD 17 is captured and stored in the second frame memory 53 as a second image buffer (image buffer 2 in the figure).
[0056]
Similarly, measurement / inspection processing of the second image data stored in the second frame memory 53 is performed at timing t3. During the measurement / inspection process, the third image data picked up by the CCD 17 is captured and stored in the first frame memory 52, which is the first image buffer.
[0057]
As described above, the image data sequentially captured by the CCD 17 are alternately stored in the first and second frame memories 52 and 53, and during the capturing period, measurement / measurement of the image data captured at the immediately preceding timing is performed. Inspection processes are performed in parallel. Then, when the last image data measurement / inspection process is completed, an area statistical process is subsequently executed.
[0058]
In the three-dimensional inspection, the height data H calculated based on the detection value (current value) by the PSD 22 is used as a 3D height buffer simultaneously with the start timing of the two-dimensional inspection, that is, at the timing t1. Stored in the height memory 42. Then, when image capture is completed at timing t4, measurement processing is subsequently performed.
[0059]
Image acquisition in such two-dimensional and three-dimensional inspections is performed during a period in which the moving speed of the stage 12 is constant. That is, as shown in FIG. 11, an image is captured and captured when the stage 12 is moving at a constant speed along a direction orthogonal to the laser scanning direction (work scanning direction in the figure). The area statistical processing in the two-dimensional inspection and the measurement processing in the three-dimensional inspection are performed while the stage 12 is accelerating / decelerating. Specifically, after the image capture in the workpiece scan direction is completed, the stage 12 moves at a predetermined pitch in the direction orthogonal to the workpiece scan direction, and is performed during the period until the velocity is again equal along the workpiece scan direction. Is called.
[0060]
FIG. 11 is an explanatory diagram of image overlap. The figure shows a part of the image capturing process.
Now, the stage 12 is moving at a constant speed in the work scanning direction Xa, and the CCD 17 images the bump BMP and the surface of the wafer W in the imaging region P1. At that time, laser scanning by the AOD 21 is performed in the imaging region P1. That is, in the alignment (position adjustment) using the recognition mark AM when the image is captured by the CCD 17, the laser scanning by the AOD 21 is set to be performed in the imaging region of the CCD 17. As a result, the two-dimensional inspection and the three-dimensional inspection are performed simultaneously and in parallel. In the figure, for example, the bump BMP to be measured in the imaging region P1 is shown with the direction of the oblique line changed.
[0061]
Next, the CCD 17 images the bump BMP and the surface of the wafer W in the imaging region P2. In this case, the CCD 17 overlaps the imaging region P2 at a predetermined interval with respect to the imaging region P1 so as not to block the bumps BMP at the image breaks in the imaging region P2 along the work scanning direction (in FIG. Wrap). The overlap amount is set in advance according to the speed of the stage 12 or the like according to the type of the wafer W or the type of BMP. After that, as described above, the CCD 17 overlaps the imaging region P3 with the imaging region P2 and overlaps the imaging region P4 with the imaging region P3.
[0062]
When the CCD 17 captures an image within the imaging area P4, the stage 12 gradually decelerates and stops. The stage 12 moves to the left in the figure along the laser scanning width (laser scanning width in the figure), and then gradually accelerates toward the workpiece scanning direction Xb. Move fast.
[0063]
In this state, the CCD 17 captures an image within the imaging area P5. In this case, in the same manner as described above, the CCD 17 sets the imaging area P5 at a predetermined interval with respect to the imaging areas P3 and P4 so that the bump BMP is not blocked by the cut of the image in the imaging area P5 along the work scan width direction. Overlap (in the figure, overlap in the pitch direction). This overlap amount is set in advance according to the speed of the stage 12 and the like according to the type of wafer W and the type of BMP, as described above. Thereafter, in the same manner as described above, the CCD 17 overlaps the imaging region P6 with the imaging region P5, overlaps the imaging region P7 with the imaging region P6, and overlaps the imaging region P8 with the imaging region P7. When the CCD 17 captures an image within the imaging area P8, the stage 12 gradually decelerates and stops.
[0064]
FIG. 12 is a comparison diagram of measurement times in a two-dimensional measurement. The figure shows a comparison of bump dimension measurement times.
The measurement time for the image data per screen is calculated based on the distance between images (for example, between the imaging regions P1 and P2) shown in FIG. 11 and the moving speed of the stage 12 in the constant velocity section. A lens with high photosensitivity is connected to the CCD 17 of this embodiment. As a result, the shutter speed of the CCD 17 can be improved and distortion of the captured image can be reduced, so that the measurement time per unit screen can be shortened by about 15 ms compared to the conventional case. Further, in the CCD 17 provided with such a lens having high photosensitivity, the image capturing time can be shortened to about half that of the conventional case. Thereby, since the moving speed of the stage 12 can be improved, it is possible to shorten the entire inspection time.
[0065]
Next, the positional deviation inspection will be described in detail.
The positional deviation inspection is performed by calculating the difference between the center of gravity position of the blob obtained at the time of dimension measurement and the center position of the bump at the theoretical coordinate position. And in this embodiment, this misalignment inspection sets beforehand the area comprised by 1 or several chip | tip among each chip | tip formed in the wafer W as a statistics acquisition area (statistical area), and each statistics acquisition This is done by calculating the difference between the average of the deviation values and the individual deviation values in the area.
[0066]
More specifically, in the misregistration inspection, the misregistration value may not be accurately measured due to mechanical errors such as variations in the position of the stage 12 that holds the wafer W by suction. Therefore, a statistical deviation value (average deviation value) is measured in a small area where the mechanical error is relatively the same, and a blob having a deviation value protruding from the average deviation value is misaligned. Detect as bump with
[0067]
FIG. 13 is an explanatory diagram of a statistics acquisition area.
The statistics acquisition area is configured by dividing each chip formed on the wafer W into a matrix in units of one or more chips. The figure shows a statistics acquisition area composed of areas corresponding to, for example, 2 × 2 4 chips. Of each statistical acquisition area, an area where a chip cannot be acquired from the wafer W is composed of areas corresponding to 1 to 3 chips.
[0068]
In the present embodiment, the measurement error due to the position variation in the θ direction of the stage 12 is further corrected according to the correction value for each imaging range calculated based on the movement error of the stage 12 acquired in advance. Further, as another method for correcting the measurement error due to the positional variation of the stage 12 in the θ direction, the wafer W is divided into four around the rotation axis of the stage 12, and among the four divided areas. You may make it correct | amend according to the average error correction value in any area | region. That is, in the correction method described above, the correction can be performed with high accuracy, but the correction calculation is complicated, so that the time for performing the correction becomes longer. On the other hand, in the correction method described later, since the area for acquiring the correction value is large, the correction accuracy is low. However, since the correction calculation is simple, the correction can be performed in a short time. Therefore, such a correction method is used according to the accuracy required for the misregistration inspection. Here, in this embodiment, the wafer W is divided into four with the rotation axis of the stage 12 as the center. However, the wafer W is centered on the rotation axis of the stage 12 according to the type of the wafer W, the type of bumps, and the like. You may make it divide | segment into two or more area | regions.
[0069]
Next, the confirmation function of the foreign object detection inspection will be described in detail with reference to FIGS.
FIG. 14 is an explanatory diagram showing a wafer map screen after inspection. In the figure, for simplification of description, a case where 9 chips are inspected is shown.
[0070]
On the map screen of the wafer, the chip 81 in which the extra is detected as a result of the foreign substance detection inspection is displayed in a different color from the other chips 82 (chip in which no extra is detected). When the chip 81 in which this extra is detected is selected, a map screen of the chip 81 is displayed as shown in FIG.
[0071]
When the extra EX displayed on the map screen of the chip 81 is selected, an image captured by the CCD 17 is displayed as shown in FIG. 17, and the extra EX can be confirmed from this image. After the display of the image data, the message shown in FIG. 16 is displayed, and the image data can be saved according to the instruction on the message screen (in the figure, for example, the key at the center of the message screen is selected).
[0072]
As described above, according to the present embodiment, the following effects can be obtained.
(1) The bump inspection apparatus 11 includes first and second frame memories 52 and 53 for storing images captured by the CCD 17, and the image input circuit 51 stores the captured image data in the first frame memory 52 or the first frame memory 52. The two frame memories 53 are alternately stored. In such a configuration, during a period in which image data is captured in one memory, measurement / inspection processing of the image data captured in the other memory is performed. As a result, the measurement / inspection process can be performed efficiently. By improving the inspection efficiency in this way, as a result, it is possible to efficiently perform a plurality of other measurement / inspections.
[0073]
(2) The misalignment inspection and the foreign matter detection process are performed during the acceleration / deceleration period of the stage 12. Thereby, it is possible to perform the measurement / inspection processing more efficiently.
[0074]
(3) The image data picked up by the CCD 17 is subjected to binarization blob processing, and based on the blob acquired thereby, two-dimensional measurement / inspection is performed. In this method, in addition to bump dimension measurement, bump misalignment inspection, bridge inspection, and missing inspection, it is possible to perform a foreign matter detection inspection on the surface of the wafer W, and each measurement and inspection can be performed with high accuracy and efficiency. Is possible.
[0075]
(4) In the misregistration inspection, the wafer W is divided into a matrix in a statistical acquisition area composed of one or a plurality of chips, and an average value of the deviation values and individual deviation values are calculated in each statistical acquisition area Based on the results. Thereby, a position shift inspection can be performed with high accuracy.
[0076]
(5) In this embodiment, since a separate new inspection device is unnecessary, an increase in cost can be suppressed.
In addition, you may implement the said embodiment in the following aspects.
[0077]
In the present embodiment, the two first and second frame memories 52 and 53 are provided, but three or more may be provided.
The recognition mark AM is not limited to the pattern shape of this embodiment.
[0078]
The statistics acquisition area is an area corresponding to one or a plurality of chips, but is not limited to this.
[0079]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide an inspection method and an inspection apparatus capable of efficiently performing a plurality of measurement / inspection items.
[Brief description of the drawings]
FIG. 1 is a schematic view of a measurement optical system of a bump inspection apparatus.
FIG. 2 is a block diagram showing a circuit configuration of a bump inspection apparatus.
FIG. 3 is a block diagram of a first control device.
FIG. 4 is a block diagram of a second control device.
FIG. 5 is a block diagram of a third control device.
FIG. 6 is an explanatory diagram of a recognition mark.
FIG. 7 is an explanatory diagram of alignment by a recognition mark.
FIG. 8 is a process flowchart of a two-dimensional measurement system.
FIG. 9 is a flowchart of measurement processing per screen.
FIG. 10 is a timing chart of image capture.
FIG. 11 is an explanatory diagram of image overlap.
FIG. 12 is a comparison diagram of measurement times of a two-dimensional measurement system.
FIG. 13 is an explanatory diagram of a statistics acquisition area.
FIG. 14 is an explanatory diagram of a wafer map screen;
FIG. 15 is an explanatory diagram of a chip map screen;
FIG. 16 is an explanatory diagram of a message screen.
FIG. 17 is an explanatory diagram of stored image data.
[Explanation of symbols]
W wafer
BMP bump
11 Bump inspection device as inspection device
12 stages
13 Imaging device
14 Scanning device
15 Detection device
52, 53 First and second frame memories as storage means

Claims (6)

A scanning device that irradiates a semiconductor wafer with measurement light of a predetermined intensity and scans the measurement light on the semiconductor wafer, and detection that detects reflected light from the semiconductor wafer and reflected light from bumps formed on the semiconductor wafer An apparatus, and an imaging device for imaging a predetermined area of the semiconductor wafer,
Bump height measurement performed based on the reflected light detected by the detection device,
With dimension measurement of bumps made on the basis of image data from the imaging device, position shift inspection, bridge inspection, have at least one Tsuogyo of missing inspection and foreign body detection test,
Binarizing the image data from the imaging device, determining whether the center of gravity position of the blob extracted by the binarization processing matches the center position of the bump at the theoretical coordinate position, inspection method characterized by the matching blob was dimension measurement of the bumps in a row Migihitsuji. A scanning device that irradiates a semiconductor wafer with measurement light of a predetermined intensity and scans the measurement light on the semiconductor wafer, and detection that detects reflected light from the semiconductor wafer and reflected light from bumps formed on the semiconductor wafer An apparatus, and an imaging device for imaging a predetermined area of the semiconductor wafer,
  Bump height measurement performed based on the reflected light detected by the detection device,
  Perform at least one of a bridge inspection, a missing inspection, and a foreign matter detection inspection together with a bump dimension measurement and a positional deviation inspection performed based on image data from the imaging device,
  In the misregistration inspection, the semiconductor wafer is divided into a plurality of statistical areas by dividing the semiconductor wafer into a matrix, and a difference between an average value of misregistration values calculated for each statistical area and individual misregistration values is calculated. Inspection method characterized by that. In the misalignment inspection, the semiconductor wafer is divided into two or more regions around the rotation axis of the stage that holds the semiconductor wafer by suction, and the position is determined according to an error correction value in the θ direction of the stage calculated in each region. The inspection method according to claim 2, wherein the deviation value is corrected. 2. The image data is captured during a constant speed movement of a stage for attracting and fixing the semiconductor wafer, and the misalignment inspection and the foreign matter detection inspection are performed during an acceleration / deceleration period of the stage. The inspection method as described in any one of thru | or 3. A scanning device that irradiates a semiconductor wafer with measurement light of a predetermined intensity and scans the measurement light on the semiconductor wafer, and detection that detects reflected light from the semiconductor wafer and reflected light from bumps formed on the semiconductor wafer An inspection apparatus for inspecting bumps formed on the semiconductor wafer, comprising an apparatus and an imaging apparatus for imaging a predetermined area of the semiconductor wafer;
  At least one of a bridge inspection, a missing inspection, and a foreign matter detection inspection is performed in addition to the bump dimension measurement and the positional deviation inspection performed based on the image data from the imaging device, and the image data from the imaging device is binarized. A control device for determining whether or not the center of gravity position of the blob extracted by the binarization processing matches the center position of the bump at the theoretical coordinate position, and measuring the size of the bump with respect to the matching blob An inspection apparatus comprising: A scanning device that irradiates a semiconductor wafer with measurement light of a predetermined intensity and scans the measurement light on the semiconductor wafer, and detection that detects reflected light from the semiconductor wafer and reflected light from bumps formed on the semiconductor wafer An inspection apparatus for inspecting bumps formed on the semiconductor wafer, comprising an apparatus and an imaging apparatus for imaging a predetermined area of the semiconductor wafer;
  At least one of a bridge inspection, a missing inspection, and a foreign matter detection inspection is performed in addition to the bump dimension measurement and the positional deviation inspection performed based on the image data from the imaging device. In the positional deviation inspection, the semiconductor wafer is arranged in a matrix. An inspection apparatus comprising: a control device that divides and divides a plurality of statistical regions and calculates a difference between an average value of positional deviation values calculated for each statistical region and individual positional deviation values.

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