JPH0648249B2 - Optical surface inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention scans the surface of a sample having a mirror-like surface such as a semiconductor substrate with a light beam, and scatters light due to irregularities on the sample surface or foreign matter. The present invention relates to an apparatus that receives light and optically inspects the presence or absence of these irregularities or foreign matter and the degree of existence.

[Conventional technology]

In the above-described optical inspection device, in order to improve the inspection accuracy, positioning of the sample for defining the inspection area,
The reproducibility of the sample movement speed should be as accurate as possible.

FIG. 6 shows the configuration of the main parts of a conventional optical inspection device of this type.

In FIG. 6 (a), the light projecting means 1 is provided with a light source 2 and a condenser lens 3, and the parallel light flux 4 projected from the light source 2 is perpendicular to the surface of the disk-shaped sample 5 by the condenser lens 3. And is projected as a light beam 6 that is condensed in a spot shape.
Abnormal place 7 such as unevenness or adhesion of fine particles on the surface of sample 5
When the light beam 6 irradiates it, pulsed scattered light 8 is generated, and this scattered light 8 is received by a photodetector 9 obliquely arranged with respect to the surface of the sample 5, and the scattered light 8 depends on the amount of received light. It outputs a pulsed electrical signal 10. When the abnormal portion 7 does not exist, the light beam 6 is specularly reflected, and the direction of specularly reflected light is perpendicular to the surface of the sample 5, so this specularly reflected light does not enter the photodetector 9.

The sample 5 is mounted on a rotary stage 11 driven by a drive device 18 having a drive speed control system 181 and a rotation speed control system 182. The sample 5 is rotated around an axis 12 of the rotary stage 11 and further in a P direction indicated by an arrow. Can be moved in a straight line. That is, in this example, the rotary stage 11 serves both as a scanning unit and a relative moving unit. Since the light projection means 1 is fixed, this movement causes the light beam 6 to move the surface of the sample 5 to the sixth position.
As shown in FIG. (B), it scans in a spiral shape, and counts the pulse-shaped component of the electric signal 10 in the inspection area defined by the position of the axis 12 by the measuring means 16 including a pulse counting circuit, and the counting result
Output 17 for inspection.

FIG. 7 shows a perspective view of a main part of the second conventional example. In this example, the light projecting means 1 also serves as the scanning means, and the surface perpendicular to the sample 5 or having an angle is defined as the scanning surface 13, and the projection direction of the light beam 6 is cyclical within the scanning surface 13. Then, the surface of the sample 5 is scanned. The line of intersection between the surface of the sample 5 and the scanning surface 13 is the scanning line 14.

In the vicinity of the sample 5, a condenser 15 having a light incident surface parallel to the scanning line 14 is arranged at an angle to receive only the pulsed scattered light 8 from the abnormal portion 7 on the surface of the sample 5. The photodetector 9 is connected to the light collecting device 15, which outputs a pulsed electric signal 10 by the scattered light 8 and counts it by the measuring means 16 to obtain a counting result 17.

The sample 5 is linearly moved in the direction of the arrow Q intersecting the scanning line 14 by the support mechanism 20 driven by the driving device 19 having the driving speed control system 191, whereby the sample 5 is scanned with the light beam 6 over the entire surface. It

[Problems to be Solved by the Invention] In the optical surface inspection apparatus described above, the normal light beam 6
In many cases, the number of times that one abnormal place 7 is scanned is stochastically less than once or a plurality of times, and the count result of the pulse-shaped component of the electric signal 10 does not indicate the actual number of abnormal places. Therefore, the counting result is calibrated for the actual number of abnormal points and then the inspection is performed. Since the scanning cycle is constant, the number of times the entire inspection area on the surface of the sample 5 is scanned varies depending on the movement speed of the sample 5 and accordingly. Therefore, the number of scanning lines per unit length, that is, the scanning line density depends on the moving speed of the sample 5, and the number of times the same abnormal portion 7 is scanned, that is, the number of detected abnormal portions is
Affected by the movement speed of. Therefore, it is necessary to maintain the same moving speed as the moving speed when calibrating the counting result of the pulsed component of the electric signal 10 for the actual number of abnormal points even in the subsequent inspection. In addition, the drive devices 18 and 19 must be provided with drive speed control systems 181, 191 and rotation speed control systems 182 that keep the moving speed unchanged. Alternatively, calibration must be performed using a sample with a known number of abnormal points in each inspection.

In the conventional example shown in FIG. 6, the rotary stage 11 which is a sample moving mechanism moves by two kinds of motions, that is, a rotary motion and a linear motion. Therefore, it is necessary to keep the speed in each motion unchanged. Requires two control systems, a drive speed control system 181 and a rotation speed control system 182.

The moving mechanism shown in the conventional example of FIG. 7 is a linear movement in one direction, which is significantly simpler than that of FIG. 6, but the drive speed control system 19 keeps the linear movement speed unchanged.
One can't miss it.

Therefore, in the optical surface inspection apparatus shown in these conventional examples, it is necessary to provide a sample moving mechanism having a precisely controlled moving speed unique to the apparatus as a part of the apparatus, and the optical system, the photodetector and its signal are required. It was extremely difficult to independently install only the processing system part and appropriately install it in a sample transfer system (for example, a belt type wafer transfer device) of an existing production line.

INDUSTRIAL APPLICABILITY The present invention does not require a sample moving mechanism dedicated to the conventional optical surface inspection apparatus, simplifies the structure of the optical surface inspection apparatus, and is applied to an existing sample transfer apparatus having different feeding speeds. It is an object of the present invention to provide a device capable of

[Means for solving problems]

According to the present invention, the number of times the entire sample is scanned and the count value of the pulse-shaped component of the electric signal output by the photodetection means are different when the moving speed of the sample is different. Focusing on the fact that is satisfied, the number of scans when the count value of the pulse-shaped component equal to the actual number of abnormal points is obtained as the reference number of scans in advance, and even when the moving speed of the sample is different, It is intended to obtain the number of abnormal points by converting the count value of the pulse-like component into a value with respect to the reference scanning number using the proportional relation of.

That is, the measuring means for counting the pulse-shaped component is further provided with the scanning number counting means and the calculating means, and the scanning number counting means counts the number of scanning times S required for the light beam to scan the entire sample, and performs the calculation. The means calculates the total sum M of the pulse-like components for the inspection region, and gives the sum M the pulse-like component count value equal to the number of known abnormal points using the reference sample in advance. is multiplied by the ratio S ₀ / S between the value and the counted number of scans of said S _0, to the abnormal part number M ₀ be calculated as _{M 0 = M (SS 0 /} S).

[Action]

The scanning number counting means S obtains the scanning number counting value S, and the calculating means multiplies the sum S of the pulse-like component counting values by the ratio S ₀ S between the reference scanning number S ₀ and the above S, M ₀ = M ( S ₀ / S)
The value of is the pulse-like component count value when the sample is scanned at the reference scan number S ₀ , that is, the actual number of abnormal points. The influence of the different moving speeds of the sample acts similarly for both due to the proportional relationship between M and S, and therefore the above M ₀
As is clear from the calculation formula of, the actions cancel each other out, so that M ₀ is
Not affected by it.

〔Example〕

FIG. 1 is a block diagram of an embodiment of the present invention. Light projection means
A light beam that is narrowly focused is projected from 21. This light beam consists of a beam expander 22, a rotary polygon mirror 23, and f · θ.
The surface of the sample 5 is scanned by the light beam 6 which is focused on the sample 5 through the scanning means 25 surrounded by the dotted line constituted by the lens 24. The beam expander 22 forms an incident thin light beam into a parallel light beam 26 having a width of about several millimeters, and the rotating polygon mirror 23 reflects the parallel light beam 26 into a light beam 27 which rotates about its axis. The f.theta. lens 24 is a lens in which the rotational angular velocity of the incident light beam 27 and the scanning velocity of the emitted light beam 6 are in a proportional relationship, and the light beam 6 is always focused on the surface of the sample 5 and linearly moved at a constant period. To scan its surface in a circular pattern. When there is an irregular portion 7 such as unevenness or adhesion of foreign matter on the sample 5, pulsed scattered light 8 is generated there. The scattered light 8 is detected by the light detecting means 28 surrounded by the alternate long and short dash line.

In the light detecting means 28, the scattered light 8 is received by an incident light condensing system 29 having a cylindrical lens on the light incident surface, the received scattered light 8 is incident on the optical fiber bundle 30, and the outgoing light condensing system 31 is operated. It is incident on the photodetector 32 via the light detector 32 and gives a pulsed component to the electric signal 10 output from the photodetector 32.

Since the surface of sample 5 is mirror-finished, sample 5
The light beam 6 irradiating the surface of is incident on the incident light condensing system 29 so as to be specularly reflected at an angle not incident. For this reason, only the extremely weak scattered light from the surface of the sample 5 and the scattered light 8 due to the abnormal portion 7 are incident on the incident light condensing system 29 and thus the photodetector 32.

The sample 5 is mounted on a sample table 34 which constitutes a relative moving means 33 surrounded by a two-dot chain line, and the sample table 34 is driven by a sample table driving device 35 in a direction perpendicular to the scanning direction of the light beam 6. As a result, the light beam 6 can scan the entire surface of the sample 5 for inspection.

The electric signal 10 output from the light detecting means 28 is given to the measuring means 36 surrounded by a solid line. The measuring means 36 is an area setting means 37, a pulse counting means 38, a scanning number counting means 39, as shown in the figure.
And a computing means 40.

As will be described later in detail, the region setting means 37 outputs a rectangular wave pulse having a time width for scanning the sample 5 and the inspection region thereof as the signal 55a and the signal 59a each time the light beam 6 scans the sample 5. Signal 55 as a square wave pulse
a is given to the scanning number counting means, and the number of scanning is counted. Further, the signal 59a is given to the pulse counting means 38, and the counting gate is opened only for the time corresponding to the width of the rectangular wave pulse, and the pulsed component of the electric signal 10 is counted.

When one inspection is completed, the pulse setting scanning end signal 70a is given from the area setting means 37 to the calculating means 40. Computing means
The scanning number counting means 39 receives the scanning end signal 70a.
From the pulse count means 38 to the scanning, and from the pulse counting means 38, the count value of the pulsed component counted in the scanning.
After Mi is read and stored as data 39a and 68a, respectively, a reset signal 68b is sent to the pulse counting means 38 to clear the counting contents.

When all the scans for the sample 5 are completed, the area setting means 37
From this, a pulsed inspection end signal 62a is given to the arithmetic means 40. The calculation means 40 receives this signal and executes calculation, and sends a reset signal 39b to the scanning number counting means 39 to clear the count content.

In the calculation means 40, the reference number of scans S ₀ obtained by calibration in advance, the distance d from the edge of the sample 5 to the inspection region, and the diameter D of the sample 5 are stored as constants. These constants and the total number of scans S, the above-mentioned number of scans i, the abnormal point number M _o count value Mi and the inspection area by performing the following calculation using the pulsed component is calculated.

Number of scans from the edge of the sample 5 to the inspection area S ₁ ; S ₁ = S (d / D) (1) Sum of count values of pulse-like components in the inspection area M: Number of abnormal points in the inspection area M ₀ ; M ₀ = M (S ₀ / S) (3) The number of abnormal points M ₀ calculated by the equation (3) is output as the inspection result 46.

The grounds for establishing the above (1), (2), and (3) will be described later.

In the present invention, the calculation means 40 performs the calculation according to the equation (3) to eliminate the influence of the different moving speeds of the sample, and the same abnormal point 7 is scanned at a number other than once and the actual abnormal point 7 is scanned. The pulse count value obtained differently from the number is corrected so that the actual number of abnormal points can always be obtained.

The above is based on the premise that the count value M of the pulse-like component is proportional to the total number of scans S of the sample 5 and is given by M = kS ... (4). k is a proportional constant. This is because the number of scanning lines per unit length, that is, the scanning line density, changes when the moving speed of the sample 5 changes, and the total number of scans S changes obviously in proportion to the number of times the abnormal portion 7 is scanned, that is, the pulse-shaped component. It is also based on the idea that the count value of changes stochastically in proportion to the scanning line density.

In the equation (4), when the count value M of the pulse-shaped component is equal to the actual number of abnormal points M ₀ , the total number of scans S is the reference number of scans S _0.
Therefore, M ₀ = kS ₀ …………………… (5), and k is eliminated from both equations (4) and (5) to obtain (3) above.
The relationship given by the formula is derived. That is, the equation (3) is to convert the count value M obtained in the case of the total number of scans S into a value for the reference number of scans S ₀ . Further, since M and S are in a proportional relationship and the moving speed of the sample 5 acts on both in the same way, their influence is canceled out in the calculation of equation (3) in which M and S are in the numerator and denominator, respectively. Thus, the value of M ₀ is not affected by the moving speed of the sample.

Fig. 2 shows that the proportional relationship shown in equation (4) holds.
It is the result confirmed experimentally using the apparatus shown in the figure.
Here detection rate is the ratio between the pulse-like component count real anomaly number M ₀ and the M as a value corresponding to the M eta = M / M ₀
Is used. Sample 5 is a silicon wafer with a diameter of 4 inches, and polystyrene latex spheres with a diameter of 0.518 μm are evenly dispersed on the surface to make it an abnormal point. The actual number M ₀ is visually counted with a microscope and shown in FIG. The detection rate η was obtained by dividing the count value M obtained by the apparatus shown by the above M ₀ . On the other hand, by changing the moving speed of the sample, the total number of scans S for the silicon wafer was obtained each time, and the horizontal axis represents S and the vertical axis represents η to show the relationship between them. It has been shown that a linear relationship, that is, a proportional relationship, passing through the origin is clearly established between η and S. The regression line obtained for FIG. 2 is η = 449 × 10 ⁻⁴ S ………… (6) for the number of scans of 1000 or more, and S is the standard scan count S ₀ for η = 100%. ₀
= 2238 is obtained. This value is obtained by actually measuring the diameter r of the spot formed by the light beam 6 on the sample surface, and dividing this value by the value D / r, which is the diameter D of the silicon wafer, that is, the light beams do not overlap the sample surface and there is a gap. It agrees with the value when scanning without opening.

FIG. 3 shows the surface of the sample 5 and one of the scanning lines along the light beam 6 for scanning the surface of the sample 5 and the photodetector 32 obtained by the scanning as a premise for explaining the specific configuration of the measuring means 36 in this embodiment. And a waveform of the electric signal 10 of FIG. FIG. 3 (a) is a plan view of the sample 5 on the sample table 34,
The light beam 6 is orthogonal to the moving direction Q of the sample 5 indicated by the arrow.
The scanning line 41 is formed by.

The peripheral region 42, which is shaded from the edge of the sample 5 to the distance d, is a region that the holder contacts when handling the sample 5, and is a region that is not an object of inspection because a large number of foreign substances are expected to adhere. Therefore, the non-hatched area is the inspection area 43.
Becomes The light beam 6 is projected to a point O on the sample table 34 to start scanning along the scanning line 41, scans the surface of the sample 5 again, and then refers to the sample table 34 again to end the scanning at a point 0 ′.
The fine particles 701, 702, 703 attached to the surface of the sample 5 all correspond to the abnormal portion 7 in FIG. The distance between point O and point 0'is invariant in any scan.

In the waveform of the electric signal 10 shown in FIG. 3 (b), the scanning repetition period is a constant time T ₀ from time t ₀₀ to time t ₀₁ , and the scanning of the light beam is from time t ₀ to t ₆ . It is performed at a constant time T between. Since the scanning speed is constant, the elapsed time t in the horizontal axis direction corresponds to the scanning distance.
The position on the scanning line shown in FIG. 3 (a) for each time is shown in parentheses.

Between times t ₀₀ and t ₀ , the light beam 6 has not yet been projected, so the level of the electrical signal 10 is at the noise level 44 determined by the noise signal of the photodetector 32 or its amplifier. At time t ₀ , the light beam 6 begins to be projected on the surface of the sample table 34. The surface of the sample stage 34 produces relatively strong scattered light, so that the level of the electrical signal 10 rises to the level V ₁ . When the light beam 6 comes to be projected on the surface of the sample 5 at time t ₁ , the scattered light sharply decreases and the level of the electric signal 10 lowers to the level V ₂ accordingly. Further time
When the light beam 6 irradiates the particles 701, 702, and 703 at t ₂ , t ₃ , and t ₄ , pulse-like scattered light is generated each time, and the electric signal 10
Although produce pulses b _1, b _2, b _3, the levels of these scattered light is weak compared to the level of the scattered light from the sample stage 34 surface, thus wave pulses b _1, b _2, b ₃ High level is V ₁
Smaller than.

As described above, the electric signal 10 shows a decrease in level in the time zone T ₁ in which the light beam 6 scans the surface of the sample 5, and using this, the electric signal 10 is used at a predetermined level slightly lower than the level V _1.
V ₃₁ as 45 is determined in advance, and at time t ₁ when the electric signal 10 falls below the level V ₃₁ during the scanning time T, one edge of the sample is again level V from the state.
_S1 other edge is detected at time t ₅ to exceed the time
At time T ₁ between t ₁ and t ₅ , the surface of the sample 5 is scanned. Further, when the time for scanning the distance d between P ₁ X ₁ or P ₂ X _{2 in} FIG. 3 (a) is τ, time t ₁ + τ and time t ₅ −τ =
T ₁ -2τ between t ₁ + T ₁ -τ is the scanning time of the inspection area.

On the other hand, with respect to the moving direction of the sample 5, since the number of scans and the moving distance of the sample are in a proportional relationship, diagonal lines are drawn from the edges P ₃ and P _{4 of} the sample 5 detected by the light beam 6 to the distance d respectively. Area Assuming the total number of scans S is S and the diameter of the sample 5 is D, the number of scans S ₁ of the light beam 6 on the light beam 6 will be reproduced below. (1) Formula S ₁ = S (d / D) … Given by (1). Therefore, from S ₁ + 1st time, S−S ₁
The inspection area is scanned by the first time, and the range for performing the summation of equation (2) is determined.

FIG. 4 is a block diagram showing an example of the circuit configuration of the measuring means 36. FIG. 5 is a waveform diagram of signals in each part of the circuit configuration of FIG. The operation of each part of FIG. 4 will be described below with reference to the waveform chart of FIG.

In FIG. 4, the electric signal 10 output from the photodetector 32 is the signal 51 from which white noise has been removed by the low-pass filter 51.
a, which is given to the area setting means 37 and the pulse counting means 38, which are surrounded by a broken line frame. In the area setting means 37, first, by the system including the comparator 52, the monostable multivibrator 53, the inverter 54, and the AND gate 55, the time equal to the time zone T ₁ during which the light beam 6 scans the surface of the sample 5 A rectangular wave signal 55a having a width is obtained.
In this system, the level of the signal 51a is compared with a predetermined level V ₃₁ by the comparator 52, and if V> V _S1, a high level “H”, and if V <V _S1 , a low level “L” output signal. Get 52a. Monostable multivibrator 53 has signal 52a
Is at a high level "H", it is triggered to output a rectangular wave having a time width equal to the scanning time T as a signal 53a. On the other hand, the inverter 54 inverts the polarity of the signal 52a into a signal 54a, supplies these signals 53a and 54a to the AND gate 55, and outputs a rectangular wave having a time width T ₁ as a signal 55a. If the light beam 6 does not scan the sample 5, T ₁ = 0 and the signal 55
a remains at low level "L".

Since this signal 55a is output as a rectangular wave each time of scanning, the number of times of scanning is obtained by counting this as a logical pulse by the scanning number counting means 39 which is a pulse counting circuit.

The signal 55a is also given to the inspection area setting system 56 and the sample detection system 57 surrounded by the one-dot chain line.

In the inspection area setting system 56, a rectangular wave signal 59a having a time width of the scanning time T ₁ -2τ of the inspection area 43 in the scanning direction of the rising light beam 6 is output each time after 2τ from the time t _1. . The delay circuit 58 gives a signal 55a, which is a rectangular wave having a time width T ₁ , with a delay τ ₁ = 2τ for a predetermined time.
And 58a, the AND gate 59 given a signal 55a of the and the signal 58a outputs a rectangular wave of duration T ₁ -τ _{1 =} T ₁ -2τ as signal 59a. If the light beam does not scan the sample 5 and the signal 55a is at the low level "L", the signal 59a also remains at the low level "L".

The signal 59a is supplied to the pulse counting means 38, and serves a gate signal for opening the T ₁ -2τ time counting gate inspection area 43 is scanned.

The signal 59a is also given to the inverter 69 to invert its polarity, and becomes a signal 69a which rises at time t ₅ when the light beam 6 finishes scanning the inspection area 43 of the sample 5 and triggers the monostable multivibrator 70. A pulsed scanning end signal 70a to the arithmetic means 40.

The sample detection system 57 outputs a pulse signal 62a for starting the calculation of the calculation means 40 when the scanning of the sample 5 by the light beam 6 is completed.

The monostable multivibrator 60 is triggered by the signal 55a and outputs as signal 60a a square wave whose time width T ₂ is longer than the scanning period T ₀ , ie T ₂ > T ₀ . Since this monostable multivibrator 60 is provided with a function capable of retriggering, when the light beam 6 repeats scanning the sample 5, it is retriggered before the falling edge of the rectangular wave of the signal 60a at the start of scanning. Signal 60a while scanning continues
Keeps the high level "H". This signal 60a is converted into a signal 61a whose polarity is inverted via the inverter 61. Therefore, the signal 61a is a signal that maintains the low level "L" while the light beam 6 scans the sample 5 and turns to the high level "H" when the scanning is completed. Therefore, when the scanning is completed, this signal 61a triggers the monostable multivibrator 62 to give the pulse-shaped inspection completion signal 62a to the arithmetic means 40.

On the other hand, in the pulse counting means 38, first the signal 51a and the signal 63a, which is obtained by applying the signal 51a to the low-pass filter 63 and removing the pulse component, are compared by the comparator 64, and the signal 51a
Only the pulse component of the difference between the signal 63a and the signal 63a is output as the signal 64a.

In the example shown in FIG. 5, the signal 64a has pulse components b ₁ , b ₂ ,
This signal 64a, which contains only b _3, is further compared with a relatively low threshold level V _{32 by a} comparator 65,
If the crest value V _p of the pulse component is V _p > V ₃₂ , a rectangular wave pulse signal 65a is output.

The signal 65a is given a second predetermined time delay τ by the delay circuit 66 and enters the AND gate 67 as the signal 66a. AND
The gate 67 receives the signal 59a applied at the same time to obtain the time t ₁ +
It operates as a counting gate opened for T _1-2 τ times between 2τ and t ₁ + T ₁ and counts the signal 67a corresponding to the portion of the signal 65a obtained by scanning in the inspection area 43 as described below. Feed to circuit 68. As a result, the fine particles 702 in the inspection area 43 are
Only the pulse signals (b ₂ ) obtained by are counted.

Here, the relationship between the signal 65a and the signal 67a will be described.
Letting the elapsed time from time t _{1 be} t, and showing signals 65a and 66a as f (t) and g (t), respectively, g (t) = f (t−τ) …………… (7) is there. The signal 67a is brought by the AND gate 67 into the signal 66a, that is, between t = τ ₁ = 2τ and t = T _{1 of} g (t). According to the equation (7), g (τ ₁ ) = f (τ ₁ −τ) = f (2τ−τ) = f
(Τ) g (T ₁ ) = f (T ₁ −τ) ………………………… (8), so the signal 67a is t = τ and t = T ₁ − of the signal 65a. τ
And a portion obtained from the inspection area 43.

The data 39a between the scanning number counting means 39 and the calculating means 40, the reset signal 39b, and the data 68a between the counting circuit 68 and the calculating means 40 and the reset signal 68b are as already described in FIG. .

〔The invention's effect〕

According to the invention, the specular surface of the sample is scanned with the light beam, the pulsed scattered light generated at the abnormal portion is received by the photodetecting means, and the pulsed component of the output signal of the photodetecting means is measured by the measuring means. In the surface inspection apparatus that counts the number of abnormalities and inspects the number of abnormal points, the counting unit includes a scanning number counting unit and a computing unit, and the scanning number counting unit measures all the scanning numbers of the sample, and the computing unit From the proportional relationship between the number of scans and the abnormal spot count value, the abnormal spot count value for the inspection region of the sample is converted into a value for the reference scan count to obtain the abnormal spot count. Since the reference number of scans is the number of scans when the above-mentioned abnormal point count value is equal to the actual number of abnormal points, the movement speed of the sample differs due to the above conversion, and even if the total number of scans differs, it is related to this. It is possible to derive the actual number of abnormal points.

Therefore, it is not necessary to integrate the light projecting means, the scanning means, the light detecting means, and the measuring means with the relative moving means of the sample,
It is possible to attach the samples to the relative moving means, which have different moving speeds, independently of each other. Therefore, it can be installed wherever necessary in the existing manufacturing line, and it can be applied to a wide range of applications such as in-line inspection of silicon wafers in the semiconductor manufacturing line and monitoring of dust generation inside semiconductor manufacturing equipment by installing it in the loader and unloader of semiconductor manufacturing equipment. Becomes

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, and FIG. 2 is a detection rate which is a ratio between the count value of abnormal points and the number of scans of a sample, which is a ratio between the count value of abnormal points and the actual number of abnormal points. And graph showing the results demonstrated by the proportional relationship between the number of scans and Figure 3, (a),
(b) is a plan view showing the sample and one scanning line and a waveform diagram of electric signals in the scanning, FIG. 4 is a block diagram showing a circuit configuration of the measuring means, and FIG. 5 is a circuit configuration of FIG. Waveform diagrams of signals in respective portions, FIGS. 6 and 7 are main portion configuration diagrams showing an example of an optical inspection apparatus in the prior art. 1, 21: light projection means, 5: sample, 6: light beam, 7: abnormal part, 701, 702, 703: fine particles, 8: scattered light, 10: electric signal, 25: scanning means, 33: relative moving means, 34: Sample stage, 35: sample stage driving device, 36: measuring means, 38: pulse counting means, 39: scanning number counting means, 40: computing means, 43: inspection area.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuaki Namba 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. (72) Keisuke Sugimoto 1 Nitta Tanabe, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 1 in Fuji Electric Co., Ltd. (56) Reference JP-A-61-132844 (JP, A) JP-A-121740 (JP, A)

Claims (2)

[Claims] 1. A light projecting means for projecting a light beam, a scanning means for linearly and repeatedly scanning a specular surface of a sample surface with the light beam, and a scanning means for scanning the sample and the sample. Relative moving means for relatively moving in a direction intersecting the direction, light detecting means for detecting scattered light from the sample surface of the light beam and a region other than the sample surface, and electricity output by the light detecting means. In the device for inspecting the sample surface, which comprises a measuring means for counting pulsed components based on scattered light generated in an abnormal portion in a predetermined inspection area set on the sample surface in the signal, the measuring means Is provided with a scanning number counting means and a computing means, the scanning number counting means counts the number of scanning times S required for the light beam to scan the entire sample, and the computing means calculates the number of the scanning regions. Calculating the sum M of the count value of the pulse-like component, and the value of the reference number of scans S ₀ was determined as the number of scans to give a pulse-like component count equals the known anomaly number using pre reference sample to the sum M is multiplied by the ratio S ₀ / S and counted the number of scans S above, the abnormal part number M ₀ M ₀
= M (S ₀ / S) The optical surface inspection apparatus is provided with a function of calculating. 2. The apparatus according to claim 1, wherein the scanning number counting means comprises a rectangular wave counting circuit, and when the light beam scans the sample surface, the electric signal output from the light detecting means is predetermined. An optical surface inspection device characterized by counting rectangular waves formed on the basis of falling below the level of.