JPH08272077A - Inspection apparatus and exposure device and device production method using the apparatus - Google Patents

Abstract

PURPOSE: To provide an inspection apparatus capable of easily inspecting the surface condition of an inspection surface with high accuracy. CONSTITUTION: This inspection apparatus has a means for irradiating the inspection surface of a reticle 1 with a pellicle 2 with light, an optical system 9b including a sensor 11b for receiving the light generated from the inspection surface and a filter means 13 for subjecting the signal from this sensor 1b to electrical low-frequency band cut filtering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus, for example, a surface state inspection apparatus for detecting foreign substances attached to a reticle or a photomask used in a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art In a process of manufacturing a semiconductor device such as an IC, a circuit pattern for exposure formed on a substrate such as a reticle or a photomask is coated with a resist by a semiconductor printing apparatus (stepper or mask aligner). It is manufactured by transferring it onto the wafer surface.

At this time, if a foreign matter such as a pattern defect or dust is present on the surface of the substrate, the foreign matter is transferred together with the pattern of the main body, which causes a decrease in the yield of IC manufacturing. Especially when a reticle is used and a circuit pattern is repeatedly printed on the wafer surface by the step-and-repeat method, if one harmful foreign substance is present on the reticle surface, the shadow of the foreign substance is printed on the entire surface of the wafer. As a result, the yield of the IC manufacturing process is greatly reduced.

Therefore, it is indispensable to detect and remove the presence of foreign matter on the substrate in the IC manufacturing process, and various inspection methods have been conventionally proposed. In general, a method of utilizing the property that foreign matter isotropically scatters light is often used.

Reticles and photomasks are roughly inspected by a method of inspecting a patterned substrate surface (pattern surface) (a pattern surface inspection method), a blank surface without a pattern on the back surface thereof, or a substrate mounted for dust prevention. The pellicle surface is inspected (pellicle surface inspection method).

For example, in Japanese Unexamined Patent Publication No. 62-188949, for example, a plurality of laminated inspection surfaces such as a pattern surface and a pellicle surface are scanned with a light beam, and each detection means is provided so as to look into each inspection surface. An inspection apparatus has been proposed which inspects a plurality of laminated surfaces at the same time.

[0007]

In order to cope with higher resolution in the future, scattered light from a foreign substance can be obtained by further narrowing down the diameter of the condensed light beam to be condensed and irradiated on the pattern surface and increasing the irradiation brightness. A method of increasing the intensity is effective, but for that purpose, it is preferable to increase the NA of the irradiation light flux. Further, in order to reduce the noise scattered light from the circuit pattern, it is preferable to reduce both the irradiation angle and the light receiving angle with respect to the reticle (reduce the angle between the reticle surface and the irradiation or light receiving optical axis).

However, when the NA of the irradiation light beam is increased and the incident angle with respect to the reticle is decreased,
The incident light beam diameter on the pellicle surface becomes large. Then, there is an increased possibility that part of the light flux will hit the pellicle frame. Then, scattered light is generated from that portion, enters the detection optical system that looks into the pellicle surface, and causes the pedestal to rise in the vicinity of the pellicle frame (see FIG. 7).

That is, in the vicinity of the pellicle frame, the swelling output of the pedestal is added to the scattered light signal from the pure foreign matter, making it difficult to detect the exact foreign matter size. This means that the inspectable area of the inspection surface becomes narrow.

The present invention solves the problems of the above-mentioned conventional techniques, and provides an inspection apparatus that can inspect the surface state of an inspection surface simply and highly accurately, and further, this inspection apparatus. It is intended to provide an exposure apparatus and a device manufacturing method using the.

[0011]

An inspection apparatus according to the present invention for solving the above-mentioned problems includes a means for irradiating an inspection surface with light, an optical system including a sensor for receiving light generated from the inspection surface, and the sensor. And a filter means for electrically applying a low-band cut filter to the signal.

Here, the inspection surface is, for example, at least one of a plurality of laminated surfaces. In addition, the inspection target is, for example, a reticle with a pellicle, and among a plurality of laminated surfaces, the first surface is the pellicle surface and the second surface is the reticle surface.
The pellicle is provided via a pellicle frame.

An exposure apparatus of the present invention is characterized by having means for inspecting a substrate by using the above inspection apparatus and means for performing an exposure transfer process using the inspected substrate. Is.

The device production method of the present invention is characterized by producing a device using the exposure apparatus.

[0015]

【Example】

<Embodiment 1> FIG. 1 is a block diagram of the first embodiment of the present invention. The laser beam 6 emitted from the laser light source 4 is converted into a wide parallel light beam by the beam expander 5, and is deflected by the optical scanning means 7 such as a vibrating mirror or a polygon mirror and the f-θ lens 8. This deflected light flux is transmitted through the pellicle surface 2 at a predetermined incident NA and incident angle ψ, and is condensed on the pattern surface 1a on which the reticle pattern is formed. Reference numeral 9a is a detection optical system that looks into the pattern surface, 10a is a condensing optical system, and 11a is a photoelectric conversion element such as a photomultiplier. Further, 9b is a detection optical system that looks into the pellicle surface, 10b is a condensing optical system, and 11b is a photoelectric conversion element such as a photomultiplier.

Laser beam illumination area 1 on pellicle surface 2
When a foreign substance is present on the surface 7, scattered light is almost isotropically generated by the foreign substance. The scattered light is guided to the light receiving surface of the photomultiplier 11b by the condensing optical system 10b.

The I / V conversion amplifier 12 converts the current value from the photomultiplier 11b into a voltage value. Next, the low-band cut filter 13 reduces the low-frequency signal component that is the noise component from the pellicle frame. As will be described later, the low-band component cut filter 13 utilizes the difference in the signal frequency band between the foreign object signal and the noise signal due to the scattered light of the pellicle frame to sufficiently reduce the noise output of the pellicle frame signal, and Is set to a frequency band that does not reduce

After that, the A / D converter 14 converts the analog signal into a digital signal. Then, the signal processing unit 15 performs processing such as size of foreign matter and existence position determination (mapping).

The above-described detection operation is performed by using a stage mechanism (not shown) while moving the reticle relatively in the direction substantially perpendicular to the optical scanning direction (arrow direction), thereby inspecting the entire surface of the reticle. ing.

Next, the detection principle of this embodiment will be described in detail.

The signal from the photomultiplier is shown in FIG.
As shown in, it is obtained as a time-series signal determined by the irradiation light beam diameter in the Y direction and the optical scanning speed. This figure makes it easy to understand how the signal of one optical scanning line in the Y direction on the pellicle surface is easily understood. FIG. 3 (a) shows the state of the signal from the foreign matter, and FIG. 3 (b) shows the irradiation light flux. 3 shows the output of the noise signal when the end of the is approaching the pellicle frame.

As shown in FIG. 3A, since the foreign matter on the pellicle is as small as 20 to 30 μm, the time width t _p of the foreign matter signal is calculated from the irradiation light beam diameter Φ in the Y direction and the optical scanning speed ν as follows. It becomes like the formula (1).

T _p = Φ / ν (1) Now, if Φ = 1.5 mm and ν = 1 × 105 mm / sec, the time width t _p is about 15 μsec, and About 66Khz
Becomes

On the other hand, the time width t _n of the noise signal generated when approaching the pellicle frame is continuous, and is determined by the time when the irradiation light beam crosses the length L _Y of the pellicle frame in the Y direction. )become that way.

T _n = L _Y / ν (2) When L _Y is 100 mm or more, the time width t _n is 1 mse.
c and the frequency is 1Khz.

As described above, it is understood that the foreign matter signal is a pulse-like relatively high frequency signal, whereas the noise signal from the pellicle frame is a considerably low frequency signal.

By utilizing the difference in the signal band and setting the cutoff frequency of the low band cut filter to about 10 kHz, the noise signal of the unnecessary pellicle frame can be reduced without lowering the intensity of the foreign matter signal. it can. The graph of FIG. 4 shows the frequency characteristics of the low band cut filter used in this embodiment.

The graph of FIG. 2 shows the state of signal output after passing through the low band component cut filter as shown in FIG. As compared with the conventional one shown in FIG. 7, the rise of the pedestal near the pellicle frame that enters the inspection area is reduced by the action of the low band component cut filter, and the pure foreign matter signal output V _P can be captured. Therefore, it is possible to detect the foreign matter in the central portion of the inspection area and in the vicinity of the pellicle frame with the same high accuracy.

In the present embodiment, an example of the structure in which the optical scanning is performed so as to be parallel to the pellicle frame has been described. However, when the optical scanning is performed in the oblique direction with respect to the pellicle frame, or the incident light flux is fixed and the inspection is performed. Even when the entire surface of the inspection board is inspected by rotating or linearly moving the board, the same effect can be obtained by setting the cutoff frequency of the low-band cut filter to an appropriate frequency.

Further, as another function and effect of this embodiment, by providing the low band cut filter, it is easy to discriminate between the continuous circuit pattern noise and the foreign signal in the specific pulse in the inspection of the pattern surface of the reticle. I have to.
That is, since the signal band of the continuous scattered light generated from the circuit pattern having regularity and the signal of the pulsed scattered light from the foreign matter are different, the low frequency cut filter causes It is possible to reduce the noise signal and improve the detected S / N ratio of the foreign matter signal.

As described above, the low-frequency cut filter can effectively remove unnecessary light from the pellicle frame, the circuit pattern, etc., and the foreign matter inspection can be performed at a high S / N ratio.

<Embodiment 2> FIG. 5 is a diagram showing an embodiment of a manufacturing system for manufacturing a semiconductor device by printing a circuit pattern of an original plate such as a reticle or a photomask on a silicon wafer. The system roughly includes an exposure device, an original storage device, an original inspection device, and a controller, which are arranged in a clean room.

Numeral 901 is a far-ultraviolet light source such as an excimer laser, numeral 902 is an illumination system unit, and the exposure position E.I. P. It has the function of illuminating the original set in the above at the same time (batch) from above with a predetermined NA (numerical aperture). Numeral 909 designates a circuit pattern formed on the original plate as a silicon wafer 9
10 is an ultra-high resolution lens system (or mirror system) for transferring onto the wafer 10, and the wafer is moved to the moving stage 9 during printing.
The exposure is repeated while shifting each shot according to the step feed of 11. Reference numeral 900 denotes an alignment optical system for aligning the original and the wafer prior to the exposure operation, and has at least one original observation microscope system. An exposure apparatus is configured by the above members.

On the other hand, reference numeral 914 denotes an original storage device which stores a plurality of originals inside. Reference numeral 913 is an original inspection device, which includes any of the configurations of the above-described respective embodiments. The original inspection device 913 detects that the selected original is pulled out from the original storage device 914 and the exposure position E.E. P. The foreign matter inspection on the original plate is performed before the setting of the foreign matter. The principle and operation of the foreign matter inspection are the same as in any of the above-described embodiments. The controller 918 is for controlling the sequence of the entire system, and controls the operation commands of the original storage device 914 and the original inspection device 913, as well as the basic operations of the exposure apparatus, such as alignment, exposure, and step feed of the wafer. To do.

The production process of a semiconductor device using the system of this embodiment will be described below. First, the original storage device 914
The original to be used is taken out and set in the original inspection device 913. Next, the original inspection device 913 inspects the foreign matter on the original. As a result of the inspection, when it is confirmed that there is no foreign matter, this original plate is exposed at the exposure position E. P. Set to.
Next, the silicon wafer 910 which is the exposure target is set on the moving stage 911. Then, according to the step-and-repeat method, the original pattern is reduced and projected onto each region of the silicon wafer while shifting each shot according to the step feed of the moving stage 911, and exposure is repeated. After the exposure on one silicon wafer is completed, the silicon wafer is accommodated and a new silicon wafer is supplied, and similarly, the exposure of the original pattern is repeated by the step & repeat method. The exposed silicon wafer that has been exposed is subjected to processing such as development and etching by an apparatus provided separately from this system. Then, a semiconductor device is manufactured through an assembly process such as dicing, wire bonding, packaging and the like. According to this embodiment, it is possible to produce a highly integrated semiconductor device having a very fine circuit pattern, which has been difficult to produce conventionally.

<Embodiment 3> FIG. 6 is a diagram showing an embodiment of an original plate cleaning inspection system for manufacturing a semiconductor device. The system is roughly: original storage device, cleaning device,
It has a drying device, an inspection device, and a controller, which are arranged in a clean chamber.

Reference numeral 920 denotes an original storage device which stores a plurality of originals and supplies the originals to be cleaned. A cleaning device 921 cleans the original plate with pure water. 92
A drying device 2 dries the washed original plate. 9
Reference numeral 23 denotes an original plate inspection apparatus, which includes the configuration of any one of the previous embodiments, and inspects foreign substances on the original plate that has been cleaned using any of the methods of the above-described embodiments. A controller 924 controls the sequence of the entire system.

The operation will be described below. First, the original plate to be cleaned is taken out from the original plate storage device 920 and supplied to the cleaning device 921. The original plate cleaned by the cleaning device 921 is sent to the drying device 922 to be dried. After the drying, it is sent to the inspection device 923, and the inspection device 923 inspects the foreign matter on the original plate by using any one of the methods of the previous embodiments. If no foreign matter is found as a result of the inspection,
The original is returned to the original storage device 920. When a foreign substance is confirmed, the original is returned to the cleaning device 921 to perform a cleaning / drying operation and then an inspection is performed again, and this is repeated until the foreign substance is completely removed. Then, the completely cleaned original plate is returned to the original plate storage device 920.

Thereafter, the cleaned original plate is set in an exposure apparatus, and a circuit pattern of the original plate is printed on a silicon wafer to manufacture a semiconductor device. As a result, it is possible to manufacture a highly integrated semiconductor device having a very fine circuit pattern, which has been difficult to manufacture in the past.

[0040]

As described above, according to the present invention, it is possible to effectively suppress the influence of unnecessary light, and it is possible to perform highly accurate foreign matter inspection in a wide area of the inspection surface. Particularly, it exhibits an excellent effect in the inspection of a reticle having a pellicle frame.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state of signal output corresponding to an inspection position.

FIG. 3 is a diagram showing a difference in signal output between a foreign matter signal and a pellicle frame signal.

FIG. 4 is a diagram showing an example of frequency characteristics of a low band cut filter.

FIG. 5 is a configuration diagram of an embodiment of an exposure apparatus having an inspection apparatus.

FIG. 6 is a configuration diagram of an embodiment of a cleaning device having an inspection device.

FIG. 7 is a diagram showing how signals are output in a conventional example.

[Explanation of symbols]

1 Reticle 2 Pellicle 3 Pellicle Frame 4 Laser Light Source 5 Beam Expander 6 Laser Beam 7 Optical Scanning Means 8 f-θ Lens 9a Detection System (for Pattern Surface) 9b Detection System (for Pellicle Surface) 10a Focusing Optical System (Pattern Surface) 10b Condensing optical system (for pellicle surface) 11a Photomultiplier (for pattern surface) 11b Photomultiplier (for pellicle surface) 12 I / V conversion amplifier 13 Low band cut filter 14 A / D converter 15 Signal processing unit 16 Sync signal detector 20 Foreign matter P ₁ Foreign matter signal

Claims (7)

[Claims] 1. A means for irradiating an inspection surface with light, an optical system including a sensor for receiving light generated from the inspection surface, and a filter means for applying an electric low-band cut filter to a signal from the sensor. An inspection apparatus having: 2. The inspection apparatus according to claim 1, wherein the inspection surface is at least one of a plurality of laminated surfaces. 3. The reticle with a pellicle to be inspected, and the plurality of laminated surfaces has a first surface as a pellicle surface and a second surface as a reticle surface. Inspection device. 4. The inspection apparatus according to claim 3, wherein the pellicle is provided via a pellicle frame. 5. The inspection apparatus according to claim 1, further comprising means for relatively moving the inspection surface and the irradiation light. 6. A means for inspecting a substrate by using the inspection apparatus according to claim 1, and a means for performing an exposure transfer process using the inspected substrate. Exposure equipment. 7. A device manufacturing method, which uses the exposure apparatus according to claim 6 to manufacture a device.