JPS62274248A - Surface stage measuring instrument - Google Patents

Abstract

PURPOSE:To detect a foreign matter bearing surface on a substrate in a short time with high accuracy by specifying the arrangement of means which detect the incidence direction of luminous flux scanning measurement surface and scattered light generated by foreign matter. CONSTITUTION:A pericle top surface 2a and a reticle reverce surface 1b are scanned by luminous flux 3 and a pericle reverse surface 2b and a reticle top surface 1a are scanned by luminous flux 4; and planed formed by the pieces of luminous flux 3 and 4 are equalized and the line l of intersection of one plane 3a between the two present planes and a plane 4a formed by scattered light which is detected by the optical part 5c of a detecting means 9c as to scattered light generated by the foreign matter on the measurement surface 1a is present above a measurement surface 2a. The scattered light generated when the luminous flux 3 impinges on the foreign matter P on the surface 2a is converged on the optical part 5a of a detecting means 9a and outputted from a photodetector 8a after being increased. Further, the light is cut off by visual field stops 6b, 6c, and 6d arranged nearby positions conjugate to measurement surfaces 1b, 1a, and 2b and the presence of the foreign matter is detected with the outputs of the photodetectors 8a-8d without varying the outputs of detecting means 9b, 9c and 9d.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a surface condition measuring device, and particularly to a reticle, a photomask, etc. on which a circuit pattern is formed, which is used in semiconductor manufacturing equipment. Keep the pellicle on and to the substrate! The present invention relates to a surface condition measuring device that accurately detects foreign matter such as impermeable dust when it is attached to the surface of a pellicle protective film when the membrane is attached.

(Prior Art) In general, in the IC'jfJ manufacturing process, semiconductor printing is performed on a circuit pattern for exposure formed on a substrate such as a reticle or photomask using a device (stepper or mask aligner) on a resist-coated surface. It is manufactured by transferring it onto eight sides.

At this time, if foreign matter such as dust is present on the substrate surface, when the circuit pattern is transferred onto the surface of the substrate, the foreign matter will also be transferred at the same time, causing a decrease in the yield of IC manufacturing.

In particular, when a step-and-repeat method is used to project and expose a circuit pattern on the reticle surface repeatedly over eight surfaces, a single piece of dust on the reticle surface is printed onto the entire wafer surface, causing a significant decrease in yield. It's coming.

Therefore, in recent years, it has become essential to detect the presence of foreign matter on a substrate in the IC manufacturing process, and various inspection methods have been proposed. For example, FIG. 2(A) is an example of a method that utilizes the property of foreign matter to scatter light in the same direction.

In the figure, the luminous flux emitted from the laser 20 is expressed as f-θ
A polygon mirror 21 placed near the entrance pupil of the lens 22
After the light is reflected by the f-theta lens 22, the reticle stage (not shown) is sequentially scanned on the surface of the reticle 24 via the aberration correction plate 23 while moving in the direction of the arrow 27.

In general, most of the circuit patterns on the surface of the reticle 24 have regularity, so that the diffracted light generated from the circuit patterns is also emitted in a direction according to a certain rule.

On the other hand, dust on the surface of the reticle 24 generates scattered light in the same direction. Therefore, at this time, the condenser lens 26-1 and the light receiver 26-
By arranging the detection system 26 consisting of two components in a direction different from the emission direction of the diffracted light generated from the circuit pattern, only the scattered light generated from dust is detected.

However, this method requires scanning and measuring the front and back surfaces of the reticle 24 with a light beam, which takes a lot of time and is mechanically very troublesome.

Further, when pellicle protective films 28a and 28b are attached to the top and bottom of the reticle 24 as shown in FIG. 2(B), dust may also adhere to the pellicle. In this case, it is necessary to use the detection system 26 to determine which surface the dust is attached to, and it is very difficult to accurately perform this determination, and the mechanism tends to become very complicated.

(Problems to be Solved by the Invention) The present invention solves the problem of the presence and size of foreign objects such as dust and defects on the surface of a substrate such as a reticle or photomask, and also by attaching a pellicle protective film to the substrate, thereby reducing the number of surfaces to be measured. It is an object of the present invention to provide a surface state measuring device which is particularly suitable for semiconductor manufacturing equipment and can easily measure on which surface foreign matter is present even when the amount of foreign matter is increased, with high precision and in a short time.

(Means for solving the problem) A plurality of laminated measurement surfaces are simultaneously scanned with a light beam, and a plurality of detection means provided for each measurement surface detects the scattered light beam generated from the measurement surfaces. In a surface condition measuring device that measures the surface condition of a plurality of measurement surfaces, a plane formed by a light beam scanning any one measurement surface a among the plurality of measurement surfaces is different from the one measurement surface a. The intersection line formed by two planes of the planes formed by the scattered light detected by the detection means corresponding to the measurement surface out of the scattered light generated by the foreign object on the measurement surface is the plurality of laminated measurement surfaces. The light beam and the detection means are arranged so as to be above or below the light beam.

Other features of the invention are described in the Examples.

(Embodiment) FIG. 1(A) is a schematic diagram of an optical system according to an embodiment of the present invention.

In the figure, 1 is the reticle, Ia and lb are the front and back surfaces of the reticle, respectively, and 2a and 2b are the reticle 1.
The upper surface of the pellicle and the lower surface of the pellicle are used to prevent dust from adhering to the surfaces. Reference numerals 3 and 4 are luminous fluxes from a light source (not shown), such as a laser, and the luminous flux 3 is scanned by a scanning means such as a polygon mirror (also not shown). The light beam 4 scans the pellicle top surface 2a and the reticle back surface 1b, and the light beam 4 scans the pellicle bottom surface 2b and the reticle top surface 1a, respectively, in a direction perpendicular to the plane of the paper. 58-5
d is an optical member in which a plurality of SELFOC lenses are arranged in one dimension, and each of the optical members 5a to 5d is a measurement surface 2a.

The focus is on Ib, Ia, and 2b. 68-6
d is a field stop arranged near a position conjugate with each measurement surface via the optical members 58 to 5d, and 7a to 7d guide the light beams passing through each of the field stops 68 to 6d to light receivers 8a to 8d. It is a light guide for

In this embodiment, the optical member 5a, field stop 6a, light guide 7a, and light receiving W8a constitute a part of the detection means 9a. Other optical members 5b to 5d, field stop 6b to
6d, light guides 7b to 7d, light receivers 8b to 8d
Similarly, the detection means 9b, 9c, and 9d each constitute a part of the detection means 9b, 9c, and 9d.

In this embodiment, the reticle upper surface 1a, the reticle lower surface 1b, the pellicle upper surface 2a, and the pellicle lower surface 2b each serve as measurement surfaces.

In this embodiment, four light beams may be used and the light beams may be incident on each measurement surface for scanning.

Figure 1 CB) is a perspective view of a portion of Figure 1 (A);
This figure shows a state in which the light beams 3 and 4 of FIG. 1(A) scan the measurement surface.

Further, FIG. 1(C) is a schematic diagram when viewed from the direction of arrow IO in FIG. 1(8).

In this example, as shown in FIG. 1 (8) and (C),
The plane 3a formed by the light beam 3 scanning any one measurement surface a (for example, the pellicle top surface 2a in this embodiment) among the plurality of planes formed by the light beams scanning each measurement surface, and the measurement surface a. is the detection means 9 corresponding to the measurement surface out of the scattered light generated by foreign matter such as dust existing on a different measurement surface b (for example, the reticle surface 1a in this embodiment).
The light beams 3, 4 and the detection means 9C are arranged so that the intersection line 2 formed by the two planes of the plane 4a formed by the scattered light detected by C exists above or below the plurality of laminated measurement surfaces. It is placed.

FIG. 1(B), ((:) shows only the optical member 5C1 and the detection means 9C, but other optical members 5a, 5b,
5d and the detection means 9a, 9b, 9d are also arranged to satisfy the requirements for navigation.

In the embodiment shown in FIG. 1(A), the light beam 3 is
Since the pellicle upper surface 2a and the reticle lower surface 1b are scanned, the planes formed by the light beams scanning the pellicle upper surface 2a and the reticle lower surface 1b are the same.

Also, the light beam 4 is similar to the light beam 3, and since it scans the pellicle lower surface 2b and the reticle upper surface 1a, the planes formed by the light beams scanning the pellicle lower surface 2b and the reticle upper surface 1a are the same.

Therefore, in this example, there are two planes in total (when four light beams are used, there are four planes). One of these two planes,
For example, the plane 4a is formed by the plane 3a and the plane 4a formed by the scattered light detected by the optical member 5C of the detection means 9C as shown in FIG. Each element is configured such that the intersection line 2 exists above (or may be below) the measurement surface 2a, as shown in FIG. 1(C).

Next, FIG. 1(A) shows the operation of this embodiment.

This will be explained using (B) and (C).

Now, it is assumed that a foreign object P such as dust exists at a position 11 on the measurement surface 2a. Then, when the light beam 3 hits the foreign object P, scattered light is generated from the foreign object in an even manner. At this time, since the detection means 9a is focused on the measurement surface 2a, the optical member 5a efficiently condenses the scattered light flux. As a result, the output from the light receiver 8a increases.

On the other hand, the other detection means 9b, 9c, and 9d have a field stop 6b near the position conjugate to the respective measurement surfaces tb, la, and 2b.

6c and 6d are arranged, the scattered light flux from the foreign object P on the measurement surface 2a is blocked by the field stops 6b, 6c, and 6d. As a result, the received light P58b, 8c, 8
The output from d does not change.

In this embodiment, the presence of foreign matter on the measurement surface is detected using the output signals from the four light receivers 88 to 8d at this time, and the foreign matter is detected by measuring the magnitude of the output signals from the light receivers 88 to 8d. The size of the image is also determined at the same time.

Furthermore, by using a plurality of detection means, the presence of foreign matter can be detected at high speed.

In contrast, Figures 3 (A) and (B) are similar to Figure 1 (C).
As in the embodiment shown in , the pellicle top surface 2a and the reticle back surface are illuminated with a luminous flux of 3! b, the light beam 4 scans the pellicle lower surface 2b and the reticle surface 1a, and the detection means 31a detects the reticle 1.
The difference from this embodiment is that the detection means 3Ia is arranged to detect the scattered light from the reticle surface 1a and the plane formed by the light beam scanning the pellicle upper surface 2a. The intersection line 2 formed by the two planes formed by the scattered light detected in FIG.
In FIG. 3(B), it is present between the top surface 2a of the belter and the back surface 1b of the reticle. In FIG. 3(A), the detection means 31a that is supposed to detect the scattered light from the reticle surface la also detects the scattered light generated from the dust adhering to the pellicle top surface 2a.
It becomes difficult to distinguish the surface on which dust is attached.

Generally, the intensity of scattered light generated by dust present on a measurement surface is proportional to the size of the dust. Therefore, in many cases, the size of dust can be determined to some extent by measuring the size of the output signal from the detection means.

However, as mentioned above, if the detection means receives scattered light from a measurement surface other than the corresponding measurement surface, the output signal from the detection means changes, making it difficult to accurately determine the size of dust. It becomes difficult.

Furthermore, in FIG. 3(B), when the stage moves in the direction of the arrow 32 and becomes as shown in FIG. 3(C), the detection means 31a detects the scattered light by the pellicle frame 33, and it appears as if there is dust. There may be cases where it is mistakenly detected as something that is being detected.

Therefore, in this embodiment, as shown in FIGS. 1B and 1C, the plane 3a formed by the light beam 3 scanning any one measurement surface 2a among the plurality of measurement surfaces is different from the measurement surface 2a. The intersection line 2 formed by the two planes of the plane 4a formed by the scattered light detected by the detection means 9c out of the scattered light generated by a foreign object on the measurement surface Ia, which is generated by a foreign object on the measurement surface Ia, exists above or below the plurality of measurement surfaces. Each element is configured so that

This makes it easy to detect the surface on which a foreign object such as dust is present, and to simultaneously determine the size of the foreign object based on the magnitude of the output signal from the detection means.

FIGS. 4 to 7 are partial schematic diagrams of other embodiments of the present invention, and each is similar to FIG. 1(C).

FIG. 4 shows a plane formed by two planes: a plane formed by the light beam scanning the measurement surface 1a, and a plane formed by the scattered light detected by the detection means 9b among the scattered light generated by a foreign object on the measurement surface 1b. This is a case where the intersection line 2 intersects below a plurality of measurement planes.

FIG. 5 shows the case where the light beam 3 is incident perpendicularly on the reticle 1, and FIG. The figure shows that two planes, the plane formed by the light beam scanning the measurement surface 1a and the plane formed by the scattered light detected by the detection means 9b among the scattered light generated by the foreign object on the measurement surface lb, are parallel to each other, that is, This is a case where the intersection line 2 formed by two planes exists at an infinite distance.

In each embodiment, each element is constructed so that the above-mentioned intersection line 1 does not exist between a plurality of laminated measurement surfaces.

(Effects of the Invention) According to the present invention, the direction of incidence of the light beam scanning each measurement surface and the arrangement of the detection means for detecting the scattered light generated from foreign matter on each measurement surface are specified as described above. According to
It is possible to achieve a surface condition measuring device that can accurately detect a measurement surface where a foreign object is present in a short time, and can also determine the size of the foreign object with high precision.

[Brief explanation of the drawing]

Figure 1 (A) is a schematic diagram of an optical system according to an embodiment of the present invention, Figures 1 (B) and (C) are explanatory diagrams of a portion of Figure 1, respectively, and Figures 2 (8) and (B 3(A), (B), ((:) are explanatory diagrams for comparing the configuration of the present invention, and FIGS. 4 to 7 are explanatory diagrams of a conventional embodiment, respectively. 1 is an explanatory diagram of a part of another embodiment of the invention. In the figure, 1 is a reticle, 2a and 2b are an upper surface of a pellicle and a lower surface of a pellicle, respectively, 3 and 4 are luminous fluxes, and 9a, 9b, 9c,
9d is a detection means, 2 is an intersection line, and P is dust. Patent Applicant: Canon Co., Ltd. Iko Figure 11 (8), (n 1st mouth CC) Broom: 3 + ¥1 Kudzu 5 Figure $ 6 Figure 7th side

Claims (1)

[Claims] (1) The surface condition of the plurality of measurement surfaces is determined by simultaneously scanning a plurality of laminated measurement surfaces with a light beam and detecting the scattered light beam generated from the measurement surfaces with a plurality of detection means provided for each measurement surface. In a surface condition measuring device for measuring a surface condition, a plane formed by a light beam scanning any one measurement surface a among the plurality of measurement surfaces and a foreign substance on a measurement surface b different from the one measurement surface a. Of the scattered light, the measurement surface b
The light beam and the detection means are arranged so that the intersection line formed by the two planes formed by the scattered light detected by the detection means corresponding to the light flux is located above or below the plurality of laminated measurement surfaces. A surface condition measuring device characterized by having: