JPH04188746A - Surface state inspecting device, surface state inspecting system and aligner - Google Patents

Abstract

PURPOSE:To prevent an erroneous detection due to scattered lights derived from an end of a substrate by a method wherein shielding means covering a periphery of the substrate is provided so that incidence of a flare may be prevented by beams for one light detecting means with respect to the other light detecting means. CONSTITUTION:A plurality of optical scanning means 100 to 106 concurrently scans a substrate 103 to be detected with a plurality of beams Bu, Bl spaced at a predetermined interval. A plurality of light detecting means 109 to 113 detects lights derived from the substrate 108 corresponding to each beam Bu, Bl and a surface state detecting means 120 detects a surface state of the substrate 103 based on an output of the optical detecting means 109 to 113. A plurality of shielding means 107, 115 covers a periphery of the substrate 108 is provided so that incidence of a flare may be prevented by beams for one of light detecting means 109 to 113 with respect to the other of the light detecting means 109 to 113. Driving means 117 moves the shielding means 115. Thus, an erroneous detection due to scattered lights derived from an end of the substrate can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a surface condition inspection apparatus and system, and further relates to an exposure apparatus using the same, and in particular to an apparatus for inspecting a surface condition on a substrate such as a reticle or a photomask used in semiconductor manufacturing equipment. The present invention relates to a surface condition inspection device and system suitable for detecting existing pattern defects and foreign matter such as dust, and an 11 optical device.

[Prior Art] Generally, in the IC manufacturing process, a circuit pattern for exposure formed on a substrate such as a reticle or a photomask is printed onto a wafer surface coated with resist using a semiconductor printing device (stepper or mask aligner). Manufactured by transcription. At this time, if foreign matter such as dust is present on the substrate surface, the foreign matter will also be transferred at the same time, causing a decrease in the yield of IC manufacturing.

In particular, when a reticle is used to repeatedly print a circuit pattern on the wafer surface using the step-and-repeat method, a single foreign object on the reticle surface may be printed on the entire surface of the wafer, which greatly reduces the yield of IC manufacturing. becomes. Therefore, in the IC manufacturing process, it is essential to detect the presence of foreign matter on the substrate, and various inspection devices have been proposed for this purpose. FIG. 8 is an example thereof, which is shown in Japanese Patent Application Laid-Open No. 62-219631 by the present applicant. In this example, the incident beam 3 that has passed through the f-〇 lens 2
is divided into two parts by a half mirror 4, and bending mirrors 5 and 10 provided on the upper and lower sides point to a point P on the substrate (reticle) 1.
, Q. The reticle 1 has a patterned circuit pattern on the lower side (lb), and a glass blank side on the upper side (Ia). When inspecting for circuit defects, it is necessary to irradiate the beam only on the patterned surface, or to inspect for foreign matter such as dust, it is necessary to irradiate the beam on both the patterned surface and the blank surface. In front of the f-theta lens, there is a rotating element (polygon mirror) not shown, which moves the beam in a direction perpendicular to the plane of the paper. As a result, the upper and lower beams scan the reticle surface in a direction perpendicular to the paper surface.

Further, in order to inspect the entire surface of the reticle, the reticle is moved in the direction from S2 to S in the figure.

The scattered light emitted from the incident point P on the reticle is transmitted to the light receiving lens 6.
An image is formed on the field stop 7a due to the action of a. Field aperture 7a
is for guiding only the necessary signal light to the photomultiplex 9a via the subsequent fiber 83, and blocks other unnecessary flare light. The light receiving system 31 for detecting the scattered light emitted from the lower incident point Q also has the same configuration as the upper light receiving system 30 described above. By the way, in order to separate foreign matter such as dust from the circuit pattern on the pattern surface, as a conventional example,
There are two methods: a method of determining the output by comparing the outputs of light receiving systems installed in two spatially different directions with respect to the beam scanning point on the reticle, and a method using depolarization.

[Section B to be invented or solved] Examples of such conventional cases include the following. 9th below
This will be explained with a diagram. FIG. 9 shows the inspection device of FIG.
This indicates when the upper beam or the left edge of the reticle is approached while the reticle is moving, for example from right to left in the figure. At this time, the lower beam is also located near the center of the reticle, and the lower detection system 31 is in the process of taking in the signal light from the lower surface of the reticle.

Since substrates such as reticles and masks have rough edges, when irradiated with a V-laser beam, strong scattered light is scattered in almost all directions. At this time, either this etch scattered light also enters the light receiving system 30 on the top surface of the reticle, or the beam on the top surface is no longer in the inspection area at this point and is not electrically captured as a signal. However, this etch scattered light also jumps into the light receiving system 31 on the bottom surface of the reticle.

The light-receiving optical system 31 (same as 30) basically guides only the scattered light (signal light) from the light emitting point Q on the reticle to the 7th field by the action of the field stop 7b. However, in the case of strong scattered light such as etch scattered light, if it hits the lens barrel (shaded area in the figure) or the edge of the lens of the light receiving optical system 31, it will become a secondary light source here (R). New scattered light is generated inside the light receiving optical system. This scattered light (dotted line in the figure) passes through the field stop 7b, passes through the Phi 8-8b, and then passes through the 7 otomaru 9.
b and is photoelectrically detected.

In the case of foreign objects such as dust, the size that should be detected on the reticle surface is Igm or 5 μm, or the intensity of the scattered light from the reticle etching mentioned above is higher than the scattered light emitted by such fine particles. is the same or better.

Therefore, even if there were no foreign objects or defects at point Q, there was a possibility that the sensor would falsely detect them as if they were present.

The present invention is an applied invention made in view of the above-mentioned prior art, and includes a surface condition inspection device and system that prevents false detection due to scattered light from the edge of a substrate to be inspected and at the same time smoothly carries out loading and unloading of the substrate. A further object of the present invention is to provide an exposure apparatus using the same.

[Means for Solving the Problems] In order to achieve the above object, the surface condition inspection apparatus of the present invention includes an optical scanning means for simultaneously scanning a substrate to be inspected with a plurality of beams separated by a predetermined distance, and each of the above-mentioned beams. a plurality of light detection means for detecting light from the substrate in correspondence with the beam; a surface state detection means for detecting a surface state of the substrate based on the output of the light detection means; and a driving means for moving the light shielding means. The light shielding means covers the peripheral edge of the substrate so as to prevent the incidence of flare caused by the beam on the other of the light detection means.

The surface condition inspection system of the present invention also includes a conveying means for conveying a substrate to be inspected to a predetermined location, and an optical scanning device for simultaneously scanning the substrate conveyed to the predetermined location with a plurality of beams separated by a predetermined distance. means, a plurality of light detection means for detecting light from the substrate corresponding to each of the beams, surface state detection means for detecting a surface state of the substrate based on the output of the light detection means, and the light detection means. a light shielding means that covers the peripheral edge of the substrate so as to prevent flare from being caused by a beam related to the other of the light detection means to be incident on one of the means; and the light shielding means is moved in response to the conveyance operation of the conveyance means. A driving means is provided.

Further, the exposure apparatus of the present invention includes an exposure means for transferring a predetermined pattern, a transport means for transporting the substrate involved in the transfer to a predetermined portion, and a predetermined amount of the substrate transported to the predetermined portion. an optical scanning means that simultaneously scans a plurality of separated beams; a plurality of light detection means that detects light from the substrate in correspondence with each of the beams; and a surface state of the substrate based on the output of the light detection means. a surface state detection means for detecting a surface condition of the substrate; a light shielding means for covering a peripheral edge of the substrate to prevent flare from a beam related to the other of the light detection means from being incident on one of the light detection means; A driving means is provided for moving in response to the transporting operation of the transporting means.

[Embodiment] FIG. 1 shows a first embodiment of the present invention. laser 100
The beam emitted from the polygon mirror 102 is expanded in luminous flux by the action of the beam expander 101 and is incident on the polygon mirror 102 .

The polygon mirror rotates in a plane perpendicular to the plane of the paper. The beam reflected by the polygon mirror 102 is sent to the f-θ lens 10
3. The beam, which has become a convergent beam due to the action of this lens, is divided into upper and lower halves by a half mirror 104, and the beam B
U, B sentences - through folding mirrors 105 and 106 respectively,
The light is focused on the upper and lower surfaces of the reticle 108. As the polygon mirror rotates, the upper and lower beams (Bu, Bu) scan the reticle surface in a direction perpendicular to the paper surface. In order to two-dimensionally inspect the inspection area on the reticle surface, the reticle foreign matter inspection stage 1]4 is moved in the direction of the arrow, / in the plane of the paper in synchronization with this laser scanning. In the above inspection mechanism,
The detection optical system when there is a foreign object on the reticle will be described below. The detection systems for the upper and lower surfaces of the reticle basically have the same configuration. The light-receiving lens 09 uses the beam condensing point on the reticle surface as an object point, and forms an image of this onto the field diaphragm 110.

As a result, only the scattered light beam (signal light) emitted by a foreign object or the like on the reticle is selectively guided to the photomultiplex 112 via the fiber 111. The photomultiplier photoelectrically converts this signal, and the subsequent CPU 120 processes this signal to determine whether there is a foreign object. The scanning position of each beam on the reticle is monitored by a detector (not shown). The CPU 120 detects the position of the foreign object on the reticle based on the scanning position and the photomultiple detection result. Reference numeral 113 denotes a lens barrel of the detection optical system, which is used to block extra light flux other than signal light. 115 and 107 are light shielding plates, 111' is an aluminum frame attached to the reticle 108, 116 is a shaft of rotation of the light shielding plate, and 117 is a cylinder.

Reticle stage] 14 has the aforementioned light shielding plate 1] 5° 10
7 is installed. In FIG. 2, a reticle 108 and light shielding plates 115, 107 are provided parallel to each other along the scanning direction of the lower beam (Bu) when viewed from the lower beam Bl side, and the lower beam, upper beam, and reticle etching (in the beam scanning direction) are arranged parallel to each other. It is fixed to the stage 114 in such a way that it does not hit the two sides (along the two sides).

Figure 1 is lower beam B! ;L is a diagram showing a state in which the reticle stage has been moved to a position corresponding to the left edge of the reticle.

At this time, the beam does not irradiate the etched portion due to the action of the light shielding plate 115.

When the lower beam Bl hits the left edge of the reticle through the light shielding plate 115, light enters the reticle upper surface detection system and generates a photoelectric output, as described in the prior art example. At this time, since the upper beam Bu is also located at the center of the inspection area 108a of the reticle, erroneous detection may occur as if there were a foreign object on this beam line. This problem is solved by the function of

In the apparatus shown in FIG. 1, when the reticle stage is moved to a position where the upper beam Bu hits the right etch of the reticle, the beam Bu does not irradiate the etched part due to the action of the light shielding plate 107. At this time, if the lower beam Bl is located at the center of the reticle surface inspection castle, if the upper beam Bu etches on the right side and emits scattered light, it will be received by the detection system on the lower surface of the reticle as in the prior art described above. It becomes a false signal. The light shielding plate 107 of the present invention solves this problem. Incidentally, in the above embodiment, the incident beam (Bu.

Bf) may be incident on a section of the reticle or may be incident perpendicularly.

3 and 4 are perspective views of this embodiment including the optical system shown in FIG.
etc. are omitted for brevity. In the figure, 200 is a reticle cassette for storing reticles, 201 is a reticle library that stores several or dozens of reticle cassettes, 202 is a hunt for transporting reticles, 203 is a linear guide, and 204 is a guide for moving the hunt 202 in a straight line. A motor feeding mechanism for driving along the guide 203, 205 a linear guide for the reticle stage 114, and 206 a reticle stage 1
14 along the linear guide 205. Furthermore, Hunt 202 motor feed mechanism 204.
206 and the cylinder 117 are controlled by the CPU 120.
We will explain the primary operation performed. Any reticle 108 to be inspected for foreign matter is taken out from any reticle cassette in the reticle library 201 either from the reticle case 200 or from the reticle carry-in/out hunt 202 . The operation of taking out the reticle 108 from the reticle cassette 200 using the reticle loading/unloading hand 202 is as follows. The reticle loading/unloading hunt 202 moves straight toward the cassette 200 while facing in the direction of the two-dot chain line in FIG. The straight movement is performed along the linear guide 203 by the motor feed mechanism 204. After the reticle loading/unloading hunt 202 holds the reticle 108 in the cassette 200, the hunt returns to its original position! Return to i (double-dashed line). At that position, the reticle loading/unloading hunt turns 180 degrees in the direction of the arrow, and the reticle foreign object inspection stage 1]4 is oriented in the transfer direction. The reticle loading/unloading hunt 202 is then driven by the motor feed mechanism 204 in a direction opposite to the one-way movement of the reticle library described above, and the reticle 108 is transferred to and from the reticle foreign object inspection stage 114. At this time, if the light-shielding plate 115 is in a position covering the etching of the reticle as shown in FIGS. 1 to 3, a part of the hand 202 and this light-shielding plate will interfere, that is, collide with each other, making it impossible to transport the reticle to the stage 114. turn into. Especially recently, the 5th
As shown in the figure, in most cases a reticle with a foreign matter adhesion prevention film (hereinafter referred to as a pellicle) is used, in which a nitrocellulose film 111'' is attached to an aluminum frame 11 to prevent foreign matter from adhering to the reticle 108. Even in the case of a reticle with a pellicle, it is sometimes necessary to check whether there is a foreign object attached to the reticle or whether there is a large foreign object attached to the pellicle surface.Currently, the above-mentioned There are many types of pellicles, and if all types of pellicle-equipped reticles are to be compatible with a device that can perform foreign object inspection, the shapes of the reticle loading/unloading hand and the reticle holding part of the foreign object inspection stage mentioned above are quite limited, and the reticle Interference between the import/export hunt 202 and the light shielding plate 115 is unavoidable.As mentioned above, FIG. At this time, the cylinder 117 rotates the light shielding plate 115 around the rotation axis 116, and the hand moves so that the light shielding plate 115 is outside the transport path of the hunt 202, as shown in the figure. 202. By making the light-shielding plate 115 movable between the light-shielding position and the avoidance position in this way, the reticle 108 can be smoothly carried onto the stage 114.

In this state, the reticle 108 is transported to the reticle loading/unloading hunt 202 or stage. Then reticle stage 1
14 is the reticle 10 from the reticle loading/unloading hunt 202
8 is picked up, the reticle is carried in and carried out, and Hunt escapes from the foreign object inspection stage. After removing the reticle holder, the stage 1]4 rotates around the light-shielding plate rotation axis 116 by the thrust of the series leader 117 before starting the reticle foreign object inspection.
5 is in the state shown in FIG. 3, the motor feed mechanism 206 drives the stage 114, and foreign matter inspection is performed as described above. After the inspection, the foreign object inspection stage returns to Figure S3, No. 4.
The reticle holder shown in the figure returns to the transfer position. When carrying out the reticle, the operation is opposite to that when carrying in the reticle, and the light shielding plate 1
15 is driven by the cylinder 117 and returns to the state shown in FIG. 4. A reticle carry-in/take-out hand 202 picks up the reticle 108 and carries it out from the stage 114. Thereafter, when inspecting the reticle, the same operation is repeated again.

The above operation is shown in FIG. 6 as a control flowchart of the CPU 120.

The light shielding plate 115 may be in the avoidance position (the state shown in FIG. 4) while the stage 114 is in the reticle transfer position. Furthermore, if necessary, the light shielding plate 107 may also be provided with a drive system to operate in the same manner as the light shielding plate 115.

FIG. 7 is a block diagram showing another embodiment of the present invention, in which the entire inspection device is incorporated into a semiconductor printing device.

301 is a far ultraviolet light source such as an excimer laser,
Reference numeral 302 denotes an illumination system unit that illuminates the reticle 108 (the pellicle frame 111' is omitted in the figure) from above uniformly over the entire area to be inspected simultaneously (indicated by -) and at a predetermined NA (numerical aperture). have.

309 has an ultra-high resolution lens system (or mirror system) for transferring the square pattern onto the wafer 310,
At the time of printing, the wafer is exposed by shifting one shot at a time according to the step feed of the moving stage 311.
0 is an alignment optical system for aligning the reticle and wafer prior to exposure, and has at least one microscope system for observing the reticle.

313 is a foreign matter inspection unit, which includes all the constituent elements shown in FIG. 1, a motor feed mechanism 206, and a guide 205. This unit has a reticle of library 20.
The reticle is inspected for foreign matter before being pulled out from the cassette in the reticle 1 by a hand 202 or the like (not shown in Figure tJIJ7) and set at the exposure position (E, P in the figure). Transport from unit 313 to exposure position is carried out by Hunt 20.
2 or other known conveying means may be used.

A controller 318 controls the basic operations of the stepper, such as alignment, exposure, and wafer step feeding sequences.

In the above configuration, the principle and operation of inspecting foreign objects etc. in the unit 313 are the same as those of the previous embodiment, and will therefore be omitted.

[Effects of the Invention] As explained above, in an apparatus that simultaneously makes #i number beams incident on a substrate and inspects the surface state of the substrate using a plurality of corresponding detection optical systems, only one detection optical system is used. On the other hand, the incidence of extra flare light due to beams from other detection systems is prevented, and as a result, the reliability of inspection is greatly improved, and at the same time, the amount of substrates carried into the inspection position can be carried out smoothly.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an optical system according to a first embodiment of the present invention. Figure 2 is a plan view of the reticle stage in Figure 1, Figures 3 and 4 are perspective views of the configuration of the device in Figure 1, Figure s5 is an explanatory diagram of the reticle with pellicle, and Figure 6 is the same as in Figure 1. Control flowchart of the device FIG. 7 is an explanatory diagram of the second embodiment of the present invention, FIG. 8 is a diagram showing the structure of a conventional example, and FIG. 9 is an explanatory diagram of problems in the conventional example. In the figure, 100...Laser 102--Polygon mirror 104--Half mirror 107-- Light shielding plate 108--Reticle 112-7 Otomaru 114--Foreign object inspection stage 115--Movable light shielding plate 117- ... Cylinder 120 ... CPU 200 - ... Reticle cassette 201 - ... Reticle library 2Q2 - ... Hunt 301 for carrying in and out reticle - ... Far ultraviolet light source 309 ... Lens system 310 ... Wafer . Applicant: Canon Co., Ltd. “7-1 Agent: Gi Marushima -Z”-B II
Keizo Nishiyama〉. 1-, L-1;- 8th ward de b

Claims (1)

[Scope of Claims] 1) Optical scanning means for simultaneously scanning a substrate to be inspected with a plurality of beams separated by a predetermined distance; and a plurality of light detection means for detecting light from the substrate in correspondence with each of the beams. surface state detection means for detecting the surface state of the substrate based on the output of the light detection means; A surface condition inspection apparatus comprising: a light shielding means for covering the peripheral edge of the substrate; and a driving means for moving the light shielding means. 2) The surface condition inspection apparatus according to claim 1, wherein the light blocking means is provided for each of the plurality of light detecting means. 3) The driving means moves at least one of the light shielding means out of the carrying-in route when carrying the board into the board inspection department along a predetermined carrying-in route. Surface condition inspection device. 4) a transport means for transporting the board to be inspected to a predetermined location;
an optical scanning means for simultaneously scanning the substrate transported to the predetermined location with a plurality of beams separated by a predetermined distance; a plurality of light detection means for detecting light from the substrate in correspondence with each of the beams; surface condition detection means for detecting the surface condition of the substrate based on the output of the photodetection means; A surface condition inspection system comprising: a light shielding means for covering a peripheral edge; and a driving means for moving the light shielding means in response to the transporting operation of the transporting means. 5) an exposure means for transferring a predetermined pattern; and a transport means for transporting the substrate involved in the transfer to a predetermined location;
an optical scanning means for simultaneously scanning the substrate transported to the predetermined location with a plurality of beams separated by a predetermined distance; a plurality of light detection means for detecting light from the substrate in correspondence with each of the beams; surface condition detection means for detecting the surface condition of the substrate based on the output of the photodetection means; An exposure apparatus comprising: a light shielding means for covering a peripheral portion; and a driving means for moving the light shielding means relative to the transporting operation of the transporting means.