JPS61104659A - Array of semiconductor solid-state image pickup element - Google Patents

Abstract

PURPOSE:To enable image pickup by even scanning of the object to be detected, by a method wherein the array of solid-state image pickup elements is arranged in staggered form in the direction of the array arrangement and allowed parallel output. CONSTITUTION:The photo receiving part 20a is arranged in staggered form. The width of a picture element is 500mum, and non-sensitive zones are provided between adjacent picture elements. In the case of 40 picture elements, when the total magnification factor of the detection system is 100, the size of one picture element is 5X8mum<2> on the sample plane, which leads to detection over a range of 5X220mum<2>: almost the same speed of inspection as that of the conventional case. The output of picture elements i-n are turned binary in parallel at the same time by a binary circuit 21; accordingly, the outputs of 40 picture elements are processed in parallel at the same time. Then, large improvement in inspection speed and in detection sensitivity can be contrived. Since the picture element overlaps widely, the miss-detection of small foreign matters 3C can be avoided. The amount of this overlap can be made nearly equal to the diameter of the small foreign matter 3C required to be detected.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is applicable to, for example, a foreign matter inspection device for detecting the smallest foreign matter on semiconductor LSI wafers, particularly on patterned wafers in intermediate steps of LSI manufacturing, at high speed and with high sensitivity. The present invention relates to a semiconductor solid-state image sensor array.

[Background of the invention]

The invention will be described in detail below using a foreign matter inspection device on sea urchins as an example.

Conventional foreign particle inspection equipment on wafers uses a combination of (:) one-dimensional high-speed scanning of the laser beam and low-speed translational movement of the sample, or (I).
I) Scanning and detection of the entire surface of the sample was performed using a linear scan based on a combination of high-speed rotation and low-speed translational movement of the sample as shown in Japanese Patent Application Laid-Open No. 55-155551 (publicly known, column 4). In addition, in vj 57-8054S (known example 1), scanning equivalent to the above (1) is realized by combining electrical scanning of a self-scanning type dimensional photoelectric conversion element array and low-speed movement of the sample. Furthermore 1. kwlorrvdirc, 1%
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H, 1!4ci44-rLLcz T<d, Vd,
4. m5. M(LL 1981, PP, 60-
70, (Known Example 2) places a self-scanning type -dimensional photoelectric conversion element array at a radial position to the sample query, and achieves scanning equivalent to the above (Il) by combining this with rotational movement of the sample. .

However, in the methods of Known Examples 1 and 2, it is impossible to avoid "missing a foreign object" when scanning a foreign object due to the dead zone existing in the adjacent portion of each photoelectric conversion element picture element.To strictly avoid this, In this case, it is necessary to install a plurality of photoelectric element arrays in a layered manner so as to cover the dead zone.This increases the number of signal processing circuits more than necessary and reduces reliability. However, even if the photoelectron arrays do not overlap, the size of the foreign object to be detected is sufficiently large compared to the above dead zone width, or the sum of the dead zone widths d[ is negligible compared to the total width of the photoelectric conversion element picture width. If it is smaller than 1.
Overlooked.

This is not a big problem. From this point of view, the methods of Known Examples 1 and 2 ignore and do not discuss the possibility of one miss due to the dead zone.

[Detection of foreign matter on patterned wafer]

Inspection of foreign substances on patterned wafers during the intermediate process of LSfJ manufacturing is essential to improve product yield and reliability. Automation of this work is described in Japanese Patent Application Laid-Open No. 55-149829.
JP-A-54-101390. Japanese Patent Publication No. 55-94145.
This is realized by a detection method using polarized light, as shown in a series of patents such as Japanese Patent Laid-Open No. 56-30650. This principle will be explained using FIGS. 21 to 28.

As shown in FIG. 17, only irradiating the illumination light 4 with respect to the surface of one wafer at an inclination angle of -2. Since reflected light and scattered light 5.6 are simultaneously generated from the foreign object 3, it is not possible to distinguish and detect only the foreign object 5 from the pattern 2. Therefore, a device was devised to use polarized laser light as the irradiation light 4 to detect foreign objects at 3°.

As shown in FIG. 18(cL), it exists on the wafer 1.

The S-polarized laser beam 4 is irradiated onto the pattern 2. -(Here, the electric vector 10 of the laser beam 4 is the query.

The case where the beam is parallel to the 1 m surface is called 8-polarized laser illumination. ,)
Generally speaking, the unevenness of pattern 20 is microscopically visible.
It is sufficiently small compared to the FJ+'tt/) wavelength, is optically smooth and smooth, and its reflected light 5 also maintains the Suj light component 11. Therefore, if the S-polarized light shielding analyzer 13 is installed in the optical path of the reflected light 5, the reflected light 5 will be blocked and the photoelectric conversion element 7
will not be reached. On the other hand, as shown in FIG.
A light control component 12 is also included. This means that the surface of the foreign object 3 is further away.
This is because the P-polarized light component 12 is generated as a result of depolarization. Therefore, the P polarized light component 14 passing through the analyzer 13
The foreign object 3 can be detected by detecting it using the light hawk conversion element 7.

Here, as shown in FIG. 17, if the angle between the longitudinal direction of the pattern 2 and the laser beam 4 is at right angles, the reflected light 5 will be completely blocked by the analyzer 13. If this angle is different from the right angle, light will not be completely blocked. This discussion is included in VOI/1 of the collection of automatic measurement and control characters.
7. Potato 2. P262 to P242.1981. According to this, this angle 10 is ±3D from the right angle
Only the reflected light from the pattern in range 17H within the range 17H enters the objective lens installed above the wafer, so the pattern reflected light 5 in this range is not completely blocked by the analyzer 13, but its intensity is 2 to 3 μrn. Since it is small enough to be distinguished from the source of foreign matter scattering, it does not pose a practical problem.

Here, the inclination angle of the polarized laser beam 4 is set to about 1° to 6°. 5 This is due to the following reasons. 19th
In the experiment shown in the figure, the intensity Vs of the 2 μm foreign object scattered light passing through the analyzer 13 component 14 for the S-polarized laser 4, and the analyzer component strength K Vp of the butter-n reflected light 5, y:I
9 (magnification 40x, N-A = 0.55) The experimental results are shown in Fig. 20. I plotted Vp. Same figure.

Since Vs can be easily distinguished from Vp when the #4 oblique angle φ is 5° or less, stable foreign object detection is possible.

Further, considering design matters, φ=1° to 3° is optimal. (Refer to Japanese Unexamined Patent Publication No. 56-30630) Here, two laser light sources 15 are used from the left and right.

The reason for this is to enable stable detection of foreign substances that generate anisotropic scattered light.

Next, a foreign matter calibration method using this detection principle will be explained with reference to FIGS. 21 to 24.

As shown in FIG. 21(-), a slot 8 is provided on the sample imaging surface to limit the detection range. This allows slit 8
Since only the scattered light within the projected area of 8 cL of the aperture onto the sample is detected at a time, the foreign object scattered light P component 14d is sufficient compared to the integrated intensity 14PK of the pattern reflected light P component within this area. If all is well, the foreign matter 3 can be detected stably. Therefore, if this surface o1t8* is made to be about the same size as the size of the foreign object to be detected (2 to 3 μm), the detection sensitivity will be optimal, but the number of scans will be increased as shown in Fig. , it has a long inspection time.On the other hand, if the aperture surface structure 8cL is made larger, inspection can be done in a shorter time, but the detection sensitivity deteriorates.In consideration of this, the area of 86
When L is 10 x 200 μm, foreign particles of 2 to 3 μm are inspected in about 2 minutes (in the case of 150C1111 wafer). This situation will be explained using FIGS. 22 and 23.

First, FIG. 22 shows a plan view (-) and a cross-sectional view (b) of the wafer surface. The pattern 2 has (1) a slight depression in the pattern and (11) a part having an angle other than perpendicular to the irradiation direction of the laser beam 4, and a small amount of scattered light P component 14P is generated from each of these parts. do. On the other hand, 0.5-2 μm
A P component 14i having a larger intensity than each of the locations (1) and (It) above is generated from the small foreign matter 3a having a size of about 2 μm or more and the large foreign matter 3k having a size of 2 μm or more.

FIG. 23 shows the signal output of the photoelectric conversion element 7 when the aperture 8a scans over the sample. The figure (cL) shows the distribution of the P components 14p (circuit pattern) and 14d (foreign matter) on the sample.When the aperture 8cL scans this distribution, the video output Vp shown in the figure (b) is obtained. , When this is binarized, the defect signal shown in the same figure (e) is obtained.In this example, the output from the small foreign object 3a and the edge of pattern 2 are the same, so the threshold shown by the broken line is higher than this output. As a result, detection is limited to only large foreign objects.

However, in the manufacture of a highly integrated LSI that is substituted for a 2SKb personal memo 9-LSI, the presence of foreign matter of 1 μm in size greatly affects the product yield, so a detection sensitivity of 1 μrm of foreign matter is required. This is the device shown in Figure 25, and if the opening 8a is limited to 5 x 5 μm2 or less, the above (1)
, the cumulative effect of the scattered light P component in (II) is 1 when the mouth 8a is
Since it is reduced compared to 0X200μ-+C, as a result,
1μIII foreign matter detection becomes possible.

However, in this case, the calibration time is about 40 times longer, and synchronization with manufacturing throughput cannot be achieved, which poses a problem in practical use.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor solid-state image sensor array that can scan an object to be detected and take an image.

[Summary of the invention]

The present invention is a semiconductor solid-state image sensor array characterized in that the arrays are arranged in a staggered manner with respect to the arrangement direction of the solid-state image sensor array, so that the arrays are output in series.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail with reference to FIGS. 1 to 15.

FIG. 1 shows how a solid-state image sensor array 20 is used in place of the stripe and g8 of the conventional example shown in FIG. 23.

FIG. 2 explains an example of the solid-state image sensor array 20. The light receiving section 20a is a silicon photodiode or a QaAsP photodiode, and among these, the PIN junction type has characteristics of high speed response and high sensitivity, and is suitable for use in the present invention. Each of the light receiving sections 20Q was arranged in a staggered pattern, and the width of the (pixel) size was 500 μm, and a dead zone was provided between the pixels. The number of pixels is 40.

For example, if the total magnification of the detection system is 1001'l (objective).

In the case of a 90 lens with a magnification of 40x and a 9-ray lens (not shown) with a magnification of 25x, the size of one pixel is 5 x 8 μrn2 on the sample surface, which is 5 x 220 μm2 in the end.
It means that you are eating a set meal while detecting the range of ゜.

The inspection speed is about the same as before.

The effects of this solid-state image sensor array 20 will be explained with reference to FIG. For comparison, the case of the solid-state image sensor array 20 is shown in (cL), (b), and (C) of the same figure, and (d) and (e) of the same figure.

(f) shows the case of the conventional example shown in FIG. The same figure (α
) shows the state in which the solid-state image sensor array 20 scans and detects the wafer, and FIG.
(C) shows the consideration signal A1, 71.4μm1m1 obtained from each pixel ("*/+'μ, ?l'L).
teeth'? ! rm Image signal L1.71.4, A1. Binarized signal L2 obtained by binarizing each threshold value VTH-Q of ml
It is a figure showing pigμ2μ22m2. Furthermore, the same figure (d
), the slit 8 is scanned over the wafer and the photoelectric conversion element 7 is
(e) shows a video signal V obtained from the photoelectric conversion element 7, and (f) shows a binary signal obtained by converting this video signal into a binary signal using a threshold value of VTR'. FIG. In addition, in the figure (α), (b), and (C), K has 5 pixels (L, jμ) to simplify the explanation.

19m). As is clear from this figure, when the output signal A1 of the pixel A is binarized using the threshold value VTH, the binarized signal 2 becomes 11'' even for the small foreign object 3a, and an improvement in sensitivity can be obtained compared to the conventional method.

FIG. 4 shows a signal processing method for pixels in the valleys of the solid-state image sensor array 20. The output of each pixel L to pixel 9 is simultaneously binarized by 21 binarization circuits in parallel, and a binarized signal ('1
”) is led to the OR circuit 22, and if a foreign object is detected in at least one picture, the output of the OR circuit becomes '1'' and is input to the foreign object memory 23. By this method, 40
The pixel outputs are simultaneously processed in parallel, and inspection speed and detection sensitivity can be significantly improved compared to when a self-running sensor is used.

However, since the pixels (light receiving portions) 20α of the solid-state image sensor array 20 overlap to a large extent, the situation shown in FIG. 5 does not occur.

That is, as shown in FIG.
When the arrangement direction of 0' and the scanning direction are perpendicular to each other, and the relationship between the dead zone between the pixel and J and the small foreign object 6G is as shown in the figure, the small foreign object 3G will be overlooked.

Therefore, as shown in FIGS. 6 and 8, if the pixels 20cL of the solid-state image sensor array 20 are arranged in a staggered manner so as to overlap in the arrangement direction, the above-mentioned oversight can be avoided. Note that the amount of overlap may be approximately equal to the diameter of the small foreign object 3G to be detected.

In FIGS. 6 and 8, the small foreign object 5G is detected by pixels j and k in duplicate. As a result, it is double counted. However, as a way to avoid this double counting, there are methods such as JP-A-56-132549 and JP-A-Sho! M-1
18187, JP-A-57-66345, JP-A-56-1
The method described in No. 26747 or Japanese Unexamined Patent Publication No. 56-118647 may be used.

FIG. 9 shows an example of application of the invention in the case of spiral scanning.

FIG. 10 shows the overall configuration of the embodiment. The wafer 1 is sucked to the wafer chuck 40 by the vacuum tube 41 and
'$ in the XY direction by the stage 46 and the Y stage 49
encourage Foreign object information detected by the solid-state image sensor array 20 is sent to a foreign object memory 23 via a binarization circuit 21 and a zero-code circuit 22.
The control circuit 32 includes the following, and is displayed by a public display device 33.

In the present invention, the pixel size is set to be approximately 5.times.8.mu. or less, so if a focus shift due to ridges on the surface of the square occurs during inspection, the foreign object detection sensitivity will be significantly reduced. Therefore, it is essential to use a configuration in which the automatic focus detection section 30 detects the amount of defocus during the inspection and feeds it back to the driver 31 of the focus mechanism motor 43.

The principle of this automatic focus function was announced on pages 225 to 224 of the preprint of the 22nd 5ICE Academic Conference, and
70540, this principle will be explained using FIGS. 11 to 13.

This method is most suitable for the present invention because it is characterized by stable automatic focusing without being affected by the pattern on the sample.

FIG. 11 shows the main parts of the automatic focus detection section 30.

i4 pattern striped pattern 60a, 6a4 on glass plate
Each of the images is projected onto the sample by the objective lens 9, but the focal point position of each is set slightly too high and slightly below the focal point of the image pickup element array 20. The images of the respective striped patterns 6On and 60-6 on the sample are magnified by the objective lens 9, reflected by the semi-transmissive mirrors 34 and 62, and imaged onto the pick-up element 61.

FIG. 12(cL) shows a projected fringe pattern imaged on the image sensor 61 in the case of wafer edge (Z>0), and the first
FIG. 2(d) shows the video signal waveform detected by the image sensor 61 in the case shown in FIG. 12(cL).

FIG. 12(b) shows a projection pattern imaged on the image sensor 61 in the case of the focused position (2=0), and FIG.
e) is the image sensor 61 in the case shown in FIG. 12(b).
The figure shows the video signal waveform detected by . Figure 12 (C) shows the projected fringe pattern that is imaged on the image sensor 61 when the wafer is r (Z>0), and Figure 12 (f) shows the projected fringe pattern that is formed on the image sensor 61. 3 shows a video signal waveform detected by the sensor 61 in the case shown in FIG.

Therefore, when the image sensor array 20 is in focus, the detection signals of the image sensor 61 become equal at the locations corresponding to the striped patterns 60cL and 0b, and the difference signal between the two becomes zero.

On the other hand, if the upper part is too p (or the lower part is too sharp), the deviation from the in-focus point of the image sensor 200 corresponds to the magnitude of the output of the difference signal, so the two-wheel signal shown in FIG. 13 is obtained. It will be done.

The figure shows an example of actual measurement of the difference signal when the sample surface is an aluminum surface and when the sample surface has a complicated pattern (Memo 9 - cell surface). 'This allows focusing within ±0.5 μm, so when the objective lens has a magnification of 90×40, stable foreign object detection becomes possible. As an automatic focusing mechanism, for example, the 10th
A motor 43. as shown in the figure. Slope 45° ball 44. The configuration using the plate spring 42 is simple.

Next, one embodiment of the candy of the present invention will be described. That is, even if the light receiving portions 200tL are formed into a trapezoidal shape and arranged in a staggered manner as shown in FIG. 14, the same effects as in the embodiment described above can be achieved. Note that 200b indicates a dead zone area.

As shown in FIGS. 15 and 16, the solid-state image sensor array has bonding pad portions 20e, 200e, and layouts @ 2od and 2o in order to connect to the external bin.

d is essential, light receiving part (pixel) 20α, 2ooa
needs to be wider than the light receiving range.

Therefore, in order to increase the detection resolution, an optical light shielding part 20c,
It is important to affix 200c by printing or the like, and to shield the bonding butt parts 20e, 200e and other parts outside the light-receiving range from light.

Further, the present invention is not limited to wafers, but can also be applied to inspection of curved products such as photomasks and reticles.

In addition, the size of the pixel is limited to about 10 x 12 μm, but it is 1.5 μm to 2.5 μm. It has been confirmed through experiments that there is no practical problem when detecting U-conducting foreign objects.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to image the object to be detected evenly regardless of the scanning direction, and it is possible to detect patterns such as minute foreign objects with high sensitivity while maintaining the high speed of inspection. Moreover, it has the effect of being able to be carried out stably.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a foreign matter inspection device in which the semiconductor solid-state image sensor array of the present invention is used, and FIG.
3 is a diagram for explaining a comparison between the present invention and a conventional example, and FIG. 4 is an output signal processing of the semiconductor solid-state device shown in FIG. 1. A diagram showing the circuit, FIG. 5 is a diagram showing the positional relationship between the dead zone and the foreign object, FIG. 6 is a diagram showing the positional relationship between the pixel (light receiving part) and the foreign object in the present invention, and the OFF diagram is the same as in FIG. 5. 8 is a diagram showing the relative scanning direction of the semiconductor solid-state image sensor to the square in FIG. 6, and FIG. 9 is a diagram showing the relative scanning direction of the semiconductor solid-state image sensor to the square in FIG. FIG. 10 is a diagram showing the relative spiral scanning of the solid-state image sensor to the query. FIG. 10 is a configuration diagram showing the embodiment shown in FIG. 1 in more detail. FIG. 11 is shown in FIG. Perspective view showing the automatic focus detection section, 12th
The figure is a diagram for explaining automatic focus detection, and Figure 13 is the first
A diagram showing the relationship between the difference output obtained from the automatic focus detection unit and out-of-focus shown in Figure 1, and Figure 14 is a semiconductor solid-state camera 1'J! with a different song from Figure 2. FIG. 15 is a diagram showing the element array in detail, FIG. 16 is a diagram specifically showing what is shown in FIG. 3, and FIG. FIG. 18 is a diagram showing the circuit pattern on the wafer and the state of reflection from the foreign matter with respect to the irradiated laser beam, and FIG. 19 is a schematic f+ view showing the first example of the conventional foreign matter detection method. , the second diagram is a graph showing measurement data of the output ratio Vs/Vp when the inclination angle - is changed in FIG. 19, and FIG. 21 is a schematic oblique view showing a second example of the conventional foreign object detection method. , Fig. 22 shows the circuit pattern on the wafer and the state of reflection from foreign objects, and Fig. 23 shows the relationship between the video signals obtained by scanning the wafer with a slit in a horizontal manner as shown in Fig. 21. The figure shown in Figure 1-24 is the second figure shown in Figure 21.
It is a schematic perspective view which shows the conventional foreign object detection method similarly to an example. [Code #5i! [Bright] 20, 200...Solid-state image sensor array for photoelectric conversion, 2
04.200a... Light receiving section, 20b, 200b...
・Dead zone. 1 竿ZL 箪ushi-shoda zutomi 2 drawing paper 77 20' Rod 8 work n diagram γ 72 drawing paper 11 rod / + fig. 2 oaf) 2θOcL ヱ15 fig.
7 Grass 79 Figure O″5” 10” Leather 22 Figure 111 χ

Claims (1)

[Claims] 1. A semiconductor solid-state image sensor array, characterized in that the array is arranged in a staggered manner with respect to the arrangement direction of the solid-state image sensor array, and is configured to output data in parallel.