JP2001135689A - Inspecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly attain inspection of a microfine pattern by maintaining an environment in which inspection of a semiconductor wafer or the like is operated in a high clean level. SOLUTION: A device main body 10 for inspecting a semiconductor wafer or the like is housed inside a clean box 3, and clear air is supplied from the clean box 4 to the inside part of the clean box 3 in which the device main body 10 is housed. The clean air unit 4 is provided with a plurality of air blowers 5a and 5b, and the air volume of clean air to be supplied to the inside part of the clean box 3 is controlled. The air volume is initialized so that a positive pressure state and an air speed optimal for inspection can be set. In a normal operation, the air speed set in the initializing state is varied according to the internal-and-external air pressure difference of the clean box 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an inspection apparatus used for inspecting a semiconductor wafer or the like on which a predetermined device pattern is formed.

[0002]

2. Description of the Related Art A semiconductor device is manufactured by forming a fine device pattern on a semiconductor wafer. When such a device pattern is formed, dust or the like may adhere to the semiconductor wafer or may be damaged, thereby causing a defect. A semiconductor device having such a defect becomes a defective device and reduces the yield.

[0003] Therefore, in order to stabilize the yield of a production line at a high level, defects generated by dust and scratches are found at an early stage, the causes thereof are identified, and effective measures are taken for production facilities and production processes. It is preferable to take it.

[0004] Therefore, when a defect is found, an inspection device is used to check the type of the defect and classify the defect, thereby identifying the equipment or process that caused the defect. I have. Here, the inspection device for checking what the defect is is like an optical microscope, so to speak.
By looking at a defect in an enlarged manner, it tries to identify what the defect is.

[0005]

When dust or the like adheres to the semiconductor wafer during the above-described inspection, an appropriate inspection cannot be performed. Therefore, the inspection of the semiconductor wafer needs to be performed in a clean environment.

As a method for keeping the environment for inspecting semiconductor wafers clean, it is effective to cover the main body of the inspection apparatus with a clean box and keep the inside of the clean box at a high degree of cleanliness. In this case, if the inside of the clean box is set to a positive pressure state and clean air is blown into the inside through a high-performance air filter, dust and the like do not flow in from the outside and the clean box Inside can be kept clean.
Therefore, even if the entire environment in which the inspection device is installed is not kept at a high level of cleanliness, dust is effectively prevented from adhering to the semiconductor wafer by locally increasing the degree of cleanliness using a clean box. As a result, the inspection of the semiconductor wafer can be appropriately performed.

Here, such a clean box is generally provided with a window that can be opened and closed from the outside for maintenance of an inspection device inside. If the window of such a clean box is opened, the state of positive pressure cannot be maintained, and dust and the like will flow in from the outside. Therefore, generally, in such a clean box, the positive pressure is maintained by controlling the flow rate of clean air while measuring the internal / external pressure difference using a differential pressure gauge or the like. For example, in a clean box, even if a window is opened, the flow rate of clean air is controlled to be large so that a positive pressure state is maintained.

Meanwhile, device patterns of semiconductor wafers to be inspected are becoming finer and finer as semiconductor devices become more highly integrated.
μm or less. In inspecting such a fine pattern, very fine dust, which has not been considered a problem in the past, is a factor that hinders an appropriate inspection.

Therefore, a clean box used in such a highly integrated semiconductor ware inspection apparatus not only keeps the cleanness of the inside uniform, but also controls, for example, the air flow flowing inside. There is a need. For example, by controlling the internal airflow so as not to cause turbulence in the air flowing on this semiconductor wafer,
Dust and the like must be prevented from accumulating on the semiconductor ware stored in the clean box. By controlling the airflow inside the clean box in this way, not only can the average cleanness inside the clean box be increased, but also the more important parts inside can be kept clean, and the accuracy can be improved. Inspection can be realized.

However, when the internal airflow is controlled in this way, not only the internal state of the clean box is simply set to a positive pressure state, but also the wind speed of the internal air is controlled by the inspection device. It must be optimized for the situation.

The present invention has been made in view of the above circumstances, and has as its object to provide an inspection apparatus which realizes a high clean environment and appropriately inspects fine patterns.

[0012]

Means for Solving the Problems The present inventor has made intensive studies to achieve the above object. As a result, first, the wind speed of clean air flowing inside the clean box was measured under positive pressure and Initial settings are made so that the wind speed is optimal for the inspection device. Then, after performing the initial setting, it has been found that it is effective to change the wind speed set in the initial setting state according to the internal / external air pressure difference.

An inspection apparatus according to the present invention is created based on the above knowledge, and includes an apparatus body for inspecting an object to be inspected, and a clean box for housing the apparatus body therein. An air supply unit for supplying clean air to the inside of the clean box; a wind speed measuring unit for measuring a wind speed of clean air supplied to the inside of the clean box; and an inside and outside of the clean box. A pressure measuring unit that measures a differential pressure; and a wind speed control unit that controls a wind speed of clean air supplied to the inside of the clean box, wherein the wind speed control unit sets the pressure inside the clean box to at least a positive pressure. In the state, the wind speed of the clean air in the clean box was initially set to a predetermined wind speed based on the detection result by the wind speed measurement unit, and the wind speed was measured by the pressure measurement unit. Serial Depending on inside and outside air pressure difference of the clean box is characterized in varying the set wind speed in the initial setting state.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows the appearance of an inspection apparatus to which the present invention is applied. This inspection apparatus 1 is for inspecting a semiconductor wafer on which a predetermined device pattern is formed,
When a defect is found in a device pattern formed on a semiconductor wafer, the defect is determined by examining what the defect is.

As shown in FIG. 1, the inspection apparatus 1 includes a clean unit 2 for keeping an environment for inspecting a semiconductor wafer clean. The clean unit 2 includes a clean box 3 formed by bending a stainless steel plate or the like to form a hollow box, and a clean air unit 4 integrally provided above the clean box 3.

The clean box 3 is provided with a window 3a at a predetermined location so that an inspector can visually recognize the inside of the clean box 3 from the window 3a. Further, the window 3a can be opened and closed in the directions of arrows X1 and X2 in the figure, for example, for maintenance of an apparatus main body disposed inside the clean box 3.

The clean air unit 4 is for supplying clean air into the clean box 3, and includes two blowers 5a and 5b disposed at different positions on the upper portion of the clean box 3, respectively. 5a, 5
b and an air filter (not shown) disposed between the clean box 3. The air filter is, for example, a HEPA filter (High Efficiency Particulate).
Air Filter) and ULPA Filter (Ultra Low Penetrat)
ion Air Filter). The clean air unit 4 is provided with blowers 5a, 5b
The dust and the like in the air blown by the above are removed by a high-performance air filter and supplied as clean air into the clean box 3.

In the inspection apparatus 1 to which the present invention is applied, the amount of clean air supplied from the clean air unit 4 into the clean box 3 is individually controlled for each of the two blowers 5a and 5b, thereby providing a clean air. The airflow in the box 3 can be appropriately controlled, which will be described later in detail. Also,
Further, in the inspection apparatus 1 to which the present invention is applied, for example, when the window 3a is opened, the amount of clean air supplied from the clean air unit 4 into the clean box 3 is reduced by two blowers. By controlling by 5a and 5b, the wind speed in the clean box is appropriately controlled, and the inflow of air from the outside is prevented. This will be described later in detail. Here, an example in which the clean air unit 4 includes two blowers 5a and 5b will be described. However, the number of blowers may be determined according to the size and shape of the clean box 3, and three or more blowers are provided. It may be configured. In this case, the amount of clean air supplied from the clean air unit 4 into the clean box 3 is
It will be controlled individually for each blower.

The clean box 3 is supported on a floor plate by supporting legs 6, and has a structure in which a lower end is opened. The air supplied from the clean air unit 4 into the clean box 3 is mainly discharged from the lower end of the clean box 3 to the outside of the clean box 3. As will be described in detail later, an opening area is provided at a predetermined location on a side surface of the clean box 3, and air supplied from the clean air unit 4 into the clean box 3 is used for cleaning the clean box 3. The air is also discharged to the outside from an opening region provided on the side surface.

As described above, the clean unit 2 always supplies the clean air from the clean air unit 4 to the clean box 3, and circulates the air circulated in the clean box 3 as an air flow outside the clean box 3. To be discharged. As a result, dust and the like generated in the clean box 3 are discharged to the outside of the clean box 3 together with the air, so that the internal environment of the clean box 3 is maintained at a very high degree of cleanness, for example, about class 1. .

The internal pressure of the clean box 3 is always maintained at a positive pressure in order to prevent air containing dust and the like from entering from the outside. Further, even when the window 3a is opened for maintenance or the like, for example, the clean box 3 has an internal air pressure in order to prevent air containing dust and the like from entering the inside. Is always maintained at positive pressure.

As shown in FIG. 2, the inspection apparatus 1 has an apparatus main body 10 housed in a clean box 3 and a predetermined device pattern is formed by the apparatus main body 10 in the clean box 3. Inspection of the semiconductor wafer is performed. Here, the semiconductor wafer to be inspected is transported in a predetermined hermetically sealed container 7, and transferred to the inside of the clean box 3 via the container 7. FIG. 2 shows the inside of the clean box 3 viewed from the direction of arrow A1 in FIG.

The container 7 has a bottom 7a, a cassette 7b fixed to the bottom 7a, and a cover 7c detachably engaged with the bottom 7a to cover the cassette 7b. The semiconductor wafers to be inspected are mounted on the cassette 7b such that a plurality of the semiconductor wafers are overlapped at a predetermined interval, and are sealed by the bottom 7a and the cover 7c.

When inspecting a semiconductor wafer,
First, a container 7 containing a semiconductor wafer is installed in a container installation space 8 provided at a predetermined position of the clean box 3. In the container installation space 8, an upper surface of an elevator 22a of an elevator 22 to be described later is
The container 7 is installed in the container installation space 8 such that the bottom 7a is located on the elevator 22a of the elevator 22.

When the container 7 is set in the container setting space 8, the engagement between the bottom 7a of the container 7 and the cover 7c is released. When the elevator 20a of the elevator 20 is lowered in the direction of arrow B in FIG. 2, the bottom 7a of the container 7 and the cassette 7b are separated from the cover 7c and moved into the clean box 3. Thereby, the semiconductor wafer to be inspected is transferred into the clean box 3 without being exposed to the outside air.

When the semiconductor wafer is transferred into the clean box 3, the semiconductor robot to be inspected is taken out of the cassette 7b and inspected by the transfer robot 23 described later.

As described above, the inspection apparatus 1 inspects the semiconductor wafer inside the clean box 3 maintained at a high degree of cleanliness. Inconveniences such as obstruction of a simple test can be effectively avoided. In addition, the semiconductor wafer to be inspected is placed in a sealed container 7 and transported, and the semiconductor wafer is transferred into the clean box 3 via the container 7. If only the inside of the container 7 is maintained at a sufficient degree of cleanness, it is possible to effectively prevent dust and the like from adhering to the semiconductor wafer without increasing the cleanliness of the entire environment in which the inspection device 1 is installed. .

By locally increasing only the degree of cleanliness at a necessary place in this way, it is possible to realize a high degree of cleanliness and to significantly reduce the cost for realizing a clean environment. The mechanical interface between the closed container 7 and the clean box 3 is a so-called SMIF (standard mechanical interface).
ace) is preferable, and in that case, a so-called SMIF-POD is used as the closed container 7.

Further, as shown in FIG. 1, the inspection apparatus 1 includes an external unit 50 in which a computer for operating the apparatus main body 10 is arranged. This external unit 50 is installed outside the clean box 3. The external unit 50 includes a display device 51 for displaying an image or the like obtained by imaging a semiconductor wafer, a display device 52 for displaying various conditions at the time of inspection, and a device body 10.
An input device 53 and the like for inputting an instruction and the like are also provided. The inspector who inspects the semiconductor wafer inputs necessary instructions from the input device 53 arranged in the external unit 50 while viewing the display devices 51 and 52 arranged in the external unit 50, and inspects the semiconductor wafer. I do.

Next, the apparatus body 10 provided inside the clean box 3 will be described in detail.

As shown in FIG. 2, the apparatus main body 10 has a support 11. The support base 11 is used to
Is a table for supporting each of the mechanisms. A support leg 12 is attached to the bottom of the support base 11.
And each mechanism provided on the support base 11 supports the support leg 1
2 has a structure supported on a floor plate independently of the clean box 3.

On the support table 11, via a vibration isolation table 13,
An inspection stage 14 on which a semiconductor wafer to be inspected is placed is provided.

The anti-vibration table 13 is for suppressing vibration from the floor, vibration generated when the inspection stage 14 is moved, and the like. And a plurality of movable legs 13b for supporting the stone surface plate 13a. And this vibration isolation table 13
When the vibration occurs, the vibration is detected and the movable leg 13b is detected.
Is driven to quickly cancel the vibration of the stone base 13a and the inspection stage 14 installed on the stone base 13a.

In the inspection apparatus 1, since a semiconductor wafer on which a fine device pattern is formed is inspected, even a slight vibration may hinder the inspection. In particular, since the inspection apparatus 1 performs inspection at a high resolution using ultraviolet light, the influence of vibration is likely to be large. Therefore, in the inspection apparatus 1, by installing the inspection stage 14 on the anti-vibration table 13, even if a slight vibration occurs in the inspection stage 14, the vibration is quickly canceled out, and the vibration is reduced. Influence is suppressed, and the inspection capability at the time of performing inspection at high resolution using ultraviolet light is improved.

The inspection stage 14 is placed on the vibration isolation table 13.
In order to stably install the vibration isolator, it is desirable that the center of gravity of the vibration isolation table 13 is located at a somewhat lower position. Therefore, in this inspection device 1, the notch 13 is formed at the lower end of the stone platen 13a.
c is provided so that the movable leg 13b supports the stone surface plate 13a at the notch 13c, thereby lowering the center of gravity of the vibration isolation table 13.

It should be noted that vibrations and the like generated when the inspection stage 14 is moved can be predicted to some extent in advance. If the vibration isolation table 13 is operated by predicting such vibrations in advance, it is possible to prevent the vibrations occurring on the inspection stage 14 from occurring. Therefore, it is desirable that the inspection apparatus 1 operates the anti-vibration table 13 by predicting in advance vibrations and the like that occur when the inspection stage 14 is moved.

The inspection stage 14 is a stage for supporting a semiconductor wafer to be inspected. The inspection stage 14 has a function of supporting a semiconductor wafer to be inspected and a function of moving the semiconductor wafer to a predetermined inspection target position.

Specifically, the inspection stage 14 includes an X stage 15 installed on the vibration isolation table 13 and an X stage 1
5, a Y stage 16 installed on the Y stage 16, a θ stage 17 installed on the Y stage 16, a Z stage 18 installed on the θ stage 17, and a suction plate 19 installed on the Z stage 18. Have.

The X stage 15 and the Y stage 16 are stages that move in the horizontal direction.
The stage 16 moves semiconductor wafers to be inspected in directions orthogonal to each other, and guides a device pattern to be inspected to a predetermined inspection position.

The .theta. Stage 17 is a so-called rotary stage for rotating a semiconductor wafer.
When inspecting the semiconductor wafer, the semiconductor wafer is rotated by the θ stage 17 so that, for example, the device pattern on the semiconductor wafer is horizontal or vertical to the screen.

The Z stage 18 is a stage that moves in the vertical direction and adjusts the height of the stage. When inspecting a semiconductor wafer, the Z stage 18 is used to adjust the inspection surface of the semiconductor wafer to an appropriate height.
Adjust the height of the stage.

The suction plate 19 is for sucking and fixing the semiconductor wafer to be inspected. During the inspection of the semiconductor wafer, the semiconductor wafer to be inspected is placed on the suction plate 19 and is sucked by the suction plate 18 to suppress unnecessary movement.

An optical unit 21 supported by a support member 20 is disposed on the vibration isolation table 12 so as to be positioned on the inspection stage 14. The optical unit 21 is for taking an image of a semiconductor wafer when inspecting the semiconductor wafer. The optical unit 21 has a function of capturing an image of a semiconductor wafer to be inspected at low resolution using visible light, and a function of capturing an image of a semiconductor wafer to be inspected at high resolution using ultraviolet light. It also has the function to perform.

As shown in FIGS. 2 and 3, an elevator 22 for taking out a cassette 7b on which a semiconductor wafer to be inspected is mounted from the container 7 and moving the cassette 7b into the clean box 3, as shown in FIGS. Is provided. Further, as shown in FIG. 3, a transfer robot 23 for transferring the semiconductor wafer, and centering and phase setting of the semiconductor wafer before placing the semiconductor wafer on the inspection stage 14 are provided on the support base 11 as shown in FIG. Is provided. FIG. 3 is a plan view schematically showing the apparatus main body 10 viewed from above.

The elevator 22 has a lifting platform 22a that can be raised and lowered, and the container 7 is installed in the container installation space 8 of the clean box 3 and the bottom 7 of the container 7
a when the engagement between the cover a and the cover 7c is released.
The lower portion 2a is operated to lower the bottom portion 7a of the container 7.
Then, the cassette 7b fixed thereto is moved into the clean box 3.

The transfer robot 23 has an operation arm 23b provided with a suction mechanism 23a at the distal end thereof. The operation arm 23b is moved and operated by the suction mechanism 23a provided at the distal end. The wafer is sucked, and the semiconductor wafer is transported in the clean box 3.

The pre-aligner 24 performs phase and centering of the semiconductor wafer with reference to an orientation flat and a notch formed in advance on the semiconductor wafer. The inspection apparatus 1 sets the pre-aligner 24 before placing the semiconductor wafer on the inspection stage 14.
In this way, the efficiency of the inspection is improved by performing the phase setting or the like.

When the semiconductor wafer is set on the inspection stage 14, first, the bottom 7 a of the container 7 and the cassette 7 b are moved into the clean box 3 by the elevator 22. Then, a semiconductor wafer to be inspected is selected from the plurality of semiconductor wafers mounted on the cassette 7b, and the selected semiconductor wafer is taken out of the cassette 7b by the transfer robot 23.

The semiconductor wafer taken out of the cassette 7b is transferred to the pre-aligner 24 by the transfer robot 23. The semiconductor wafer conveyed to the pre-aligner 24 is subjected to phase setting and center setting by the pre-aligner 24. Then, the semiconductor wafer on which the phase setting and the center setting have been performed is transferred to the inspection stage 14 by the transfer robot 23, and is placed on the suction plate 19 to perform the inspection.

When the semiconductor wafer to be inspected is transported to the inspection stage 14, the semiconductor wafer to be inspected next is taken out of the cassette 7b by the transport robot 23 and transported to the pre-aligner 24. Then, while the inspection of the semiconductor wafer previously conveyed to the inspection stage 14 is being performed, the phase of the semiconductor wafer to be inspected next and the centering are performed. When the inspection of the semiconductor wafer previously transported to the inspection stage 14 is completed, the next semiconductor wafer to be inspected is immediately transported to the inspection stage 14.

As described above, the inspection apparatus 1 performs the phase adjustment and the center adjustment by the pre-aligner 24 before transporting the semiconductor wafer to be inspected to the inspection stage 14 so that the inspection stage 14 The time required for positioning the semiconductor wafer can be reduced. Further, the inspection apparatus 1 takes out the semiconductor wafer to be inspected next from the cassette 7b by using the time during which the inspection of the semiconductor wafer previously carried to the inspection stage 14 is being performed, and performs phase detection by the pre-aligner 24. By performing the centering and the centering, the overall time can be reduced, and the inspection can be performed efficiently.

In the inspection apparatus 1, the elevator 22, the transfer robot 23, the pre-aligner 2
4 are installed on the support base 11 so as to be lined up in a straight line, as shown in FIG. The respective installation positions are determined so that the distance L1 between the elevator 22 and the transfer robot 23 is substantially equal to the distance L2 between the transfer robot 23 and the pre-aligner 24. Further, from the viewpoint of the transfer robot 23,
The inspection table 14 is arranged so as to be positioned in a direction substantially orthogonal to the direction in which the elevators 22 and the pre-aligners 24 are arranged.

The inspection apparatus 1 can quickly and accurately transport a semiconductor wafer, which is an object to be inspected, by arranging each mechanism as described above.

That is, in the inspection apparatus 1, since the distance L1 between the elevator 22 and the transfer robot 23 is substantially equal to the distance L2 between the transfer robot 23 and the pre-aligner 24, Transfer robot 23
Without changing the length of the arm 23b of the cassette 7b.
The semiconductor wafer taken out of the wafer can be transferred to the pre-aligner 24. Therefore, in the inspection apparatus 1, since an error or the like generated when the length of the arm 23b of the transfer robot 23 is changed does not matter, the operation of transferring the semiconductor wafer to the pre-aligner 24 can be performed accurately. Further, since the elevator 22, the transfer robot 23, and the pre-aligner 24 are arranged in a straight line, the transfer robot 23 can transfer the semiconductor wafer taken out of the cassette 7b to the pre-aligner 24 only by linear movement. . Therefore, in the inspection apparatus 1, the operation of transporting the semiconductor wafer to the pre-aligner 24 can be performed extremely accurately and quickly.

Further, in the inspection apparatus 1, the elevator 22 and the pre-aligner 24 are viewed from the transfer robot 23.
Are arranged so that the inspection table 14 is positioned in a direction substantially perpendicular to the direction in which the semiconductor wafers are arranged, so that the semiconductor wafer is transported to the inspection table 14 by the linear movement of the transport robot 23. be able to. Therefore,
In this inspection apparatus 1, a semiconductor wafer is placed on an inspection table 1
4 can be performed very accurately and quickly. In particular, the inspection apparatus 1 inspects a semiconductor wafer on which a fine device pattern is formed.
Since the transfer and positioning of the semiconductor wafer to be inspected must be performed very accurately, the above arrangement is very effective.

Next, the inspection apparatus 1 will be described in more detail with reference to the block diagram of FIG.

As shown in FIG. 4, the external unit 50 of the inspection apparatus 1 has an image processing computer 60 connected to a display device 51 and an input device 53a, and a control device connected to a display device 52 and an input device 53b. Computer 61
And are arranged. In FIG. 1, the input device 53a connected to the image processing computer 60 and the input device 53b connected to the control computer 61 are collectively shown as the input device 53.

When inspecting a semiconductor wafer, the image processing computer 60 controls the charge-coupled device (CCD) camera 30 installed inside the optical unit 21.
A computer that takes in and processes an image obtained by imaging a semiconductor wafer by 31. That is, this inspection device 1
Performs inspection of the semiconductor wafer by processing and analyzing the image of the semiconductor wafer captured by the CCD cameras 30 and 31 installed inside the optical unit 21 by the image processing computer 60.

The input device 53a connected to the image processing computer 60 is for inputting, to the image processing computer 30, instructions necessary for analyzing images taken from the CCD cameras 30 and 31. And comprises, for example, a pointing device such as a mouse, a keyboard, and the like. The display device 51 connected to the image processing computer 60 is for displaying analysis results of images taken from the CCD cameras 30 and 31, and is composed of, for example, a CRT display or a liquid crystal display.

When inspecting the semiconductor wafer, the control computer 61 performs the inspection stage 14, the elevator 2
2. A computer for controlling the transfer robot 23, the pre-aligner 24, and each device inside the optical unit 12. That is, the inspection apparatus 1 controls the control computer so that an image of the semiconductor wafer to be inspected is picked up by the CCD cameras 30 and 31 installed inside the optical unit 21 when inspecting the semiconductor wafer. 61, the inspection stage 14, the elevator 2
2. It controls the transfer robot 23, the pre-aligner 24, and each device inside the optical unit 21.

The control computer 61 has a function of controlling the blowers 5a and 5b of the clean air unit 4. That is, the inspection apparatus 1 controls the blowers 5 a and 5 b of the clean air unit 4
Is controlled to constantly supply clean air into the clean box 3 when inspecting a semiconductor wafer,
Further, the air flow in the clean box 3 can be controlled.

The control computer 61 maintains the pressure in the clean box 3 at a positive pressure, and controls the air velocity in the clean box 3 to control the air flow in the clean box 3. To be equal to or greater than a predetermined amount.
Has a function of controlling the blowers 5a and 5b. Specifically, in the clean box 3, there are an anemometer 55 for measuring the wind speed of the clean air blown by the blowers 5a and 5b, and a differential pressure gauge 56 for detecting a pressure difference between the inside and the outside of the clean box 3. Provided, a control computer 6
The measurement is performed on the basis of these measurement results input to (1).

The input device 53 b connected to the control computer 61 includes the inspection stage 14, the elevator 22, the transfer robot 23 and the pre-aligner 24, each device inside the optical unit 21, and the blower of the clean air unit 4. This is for inputting an instruction necessary for controlling 5a, 5b and the like to the control computer 61, and includes, for example, a pointing device such as a mouse or a keyboard. The control computer 6
1 is for displaying various conditions and the like at the time of inspection of a semiconductor wafer.
It consists of an RT display, a liquid crystal display and the like.

The image processing computer 60 and the control computer 61 can exchange data with each other by a memory link mechanism. That is,
Image processing computer 60 and control computer 61
Are connected to each other via memory link interfaces 60a and 61a provided respectively, so that the image processing computer 60 and the control computer 51 can exchange data with each other.

On the other hand, inside the clean box 3 of the inspection apparatus 1, the semiconductor wafer placed in the sealed container 7 and transported is taken out from the cassette 7 b of the container 7 and set on the inspection stage 14. As described above, the elevator 22, the transfer robot 23, and the pre-aligner 24 are arranged as mechanisms. These are connected to a control computer 61 arranged in the external unit 50 via a robot control interface 61b.
Then, control signals are sent from the control computer 61 to the elevator 22, the transfer robot 23, and the pre-aligner 24 via the robot control interface 61b.

That is, the semiconductor wafers conveyed in the closed container 7 are transferred to the cassette 7 of the container 7.
b, when it is taken out and installed on the inspection stage 14,
Control signals are sent from the control computer 61 to the elevator 22, the transfer robot 23, and the pre-aligner 24 via the robot control interface 61b. Then, the elevator 22, the transfer robot 23, and the pre-aligner 24 operate based on the control signal, and as described above, the semiconductor wafers that have been transported in the closed container 7 are transferred to the cassette 7b of the container 7. , And the phase and center are set by the pre-aligner 25 and set on the inspection stage 14.

Further, an anti-vibration table 13 is provided inside the clean box 3 of the inspection apparatus 1, and the X-stage 15 and the Y-stage 1
6, an inspection stage 14 including a θ stage 17, a Z stage 18, and a suction plate 19 is provided.

Here, the X stage 15 and the Y stage 1
6, the θ stage 17, the Z stage 18, and the suction plate 19 are connected to a control computer 61 arranged in the external unit 50 via a stage control interface 61c. Then, control signals are sent from the control computer 61 to the X stage 15, the Y stage 16, the θ stage 17, the Z stage 18, and the suction plate 19 via the stage control interface 61c.

That is, when inspecting a semiconductor wafer, control signals are sent from the control computer 61 to the X stage 15, the Y stage 16, the θ stage 17, the Z stage 18, and the suction plate 19 via the stage control interface 61c. Sent out. And X stage 1
5, Y stage 16, θ stage 17, Z stage 18
The suction plate 19 operates on the basis of the control signal to suck and fix the semiconductor wafer to be inspected by the suction plate 19, and the semiconductor stage is controlled by the X stage 15, the Y stage 16, the θ stage 17 and the Z stage 18. The wafer is moved to a predetermined position, angle and height.

As described above, the optical unit 21 is also provided on the vibration isolation table 12. The optical unit 21 is for taking an image of the semiconductor wafer at the time of inspecting the semiconductor wafer, and as described above, the function of taking an image of the semiconductor wafer to be inspected at a low resolution using visible light. And a function of capturing an image of a semiconductor wafer to be inspected with high resolution using ultraviolet light.

Inside the optical unit 21, there is provided a mechanism for capturing an image of a semiconductor wafer with visible light.
A CCD camera 30 for visible light, a halogen lamp 32,
An optical system 33 for visible light, an objective lens 34 for visible light, and an autofocus controller 35 for visible light are arranged.

When an image of the semiconductor wafer is taken with visible light, the halogen lamp 32 is turned on. Here, the driving source of the halogen lamp 32 is the external unit 50.
Is connected via a light source control interface 61d to a control computer 61 arranged in the computer. The driving source of the halogen lamp 32 includes the control computer 6.
1 transmits a control signal via the light source control interface 61d. The turning on / off of the halogen lamp 32 is performed based on this control signal.

When taking an image of a semiconductor wafer with visible light, the halogen lamp 32 is turned on, and the visible light from the halogen lamp 32 is transmitted to the visible light optical system 33.
Then, the semiconductor wafer is illuminated by being applied to the semiconductor wafer via the visible light objective lens 34. Then, the image of the semiconductor wafer illuminated by the visible light is converted into a visible light objective lens 34.
And enlarges the enlarged image with the visible light CCD camera 30.
To capture an image.

Here, the visible light CCD camera 30 is connected to an image processing computer 60 provided in the external unit 50.
Are connected via an image capture interface 60b. Then, the image of the semiconductor wafer captured by the visible light CCD camera 30 is captured by the image processing computer 60 via the image capturing interface 60b.

When the image of the semiconductor wafer is captured with visible light as described above, the automatic focus position is adjusted by the visible light autofocus controller 35. That is, the visible light autofocus control unit 35 detects whether or not the distance between the visible light objective lens 34 and the semiconductor wafer matches the focal length of the visible light objective lens 34. Is a visible light objective lens 34
Alternatively, the Z stage 18 is moved so that the inspection target surface of the semiconductor wafer coincides with the focal plane of the visible light objective lens 34.

Here, the visible light auto-focus control unit 35 sends an auto-focus control interface 61 to a control computer 61 arranged in the external unit 50.
e. Then, a control signal is sent from the control computer 61 to the visible light autofocus control unit 35 via the autofocus control interface 61e. Automatic focus positioning of the visible light objective lens 34 by the visible light autofocus controller 35 is performed based on this control signal.

The optical unit 21 includes a CCD camera 31 for ultraviolet light and a laser light source 3 for ultraviolet light as a mechanism for capturing an image of a semiconductor wafer with ultraviolet light.
6, an optical system 37 for ultraviolet light, and an objective lens 38 for ultraviolet light
And an ultraviolet light autofocus control section 39.

When an image of the semiconductor wafer is taken with ultraviolet light, the ultraviolet laser light source 36 is turned on. Here, the drive source of the ultraviolet laser light source 36 is connected to a control computer 61 arranged in the external unit 50 via a light source control interface 61d. A control signal is sent from the control computer 61 to the drive source of the ultraviolet laser light source 36 via the light source control interface 61d. Turning on / off the ultraviolet laser light source 36
The light is turned off based on this control signal.

It is preferable that the ultraviolet laser light source 36 emits an ultraviolet laser having a wavelength of about 266 nm. An ultraviolet light laser having a wavelength of about 266 nm is obtained as a fourth harmonic of a YAG laser. Further, a laser light source having an oscillation wavelength of about 166 nm has been developed, and such a laser light source may be used as the ultraviolet laser light source.

When capturing an image of a semiconductor wafer with ultraviolet light, the ultraviolet laser light source 36 is turned on, and the ultraviolet light from the ultraviolet laser light source 36 is transmitted to the ultraviolet optical system 37 and the objective lens for ultraviolet light. The semiconductor wafer is illuminated by being applied to the semiconductor wafer via 38. Then, the image of the semiconductor wafer illuminated by the ultraviolet light is enlarged by the ultraviolet light objective lens 38, and the enlarged image is captured by the ultraviolet light CCD camera 31.

Here, the ultraviolet CCD camera 31 is connected to the image processing computer 60 provided in the external unit 50.
Are connected via an image capture interface 60c. The image of the semiconductor wafer captured by the ultraviolet light CCD camera 31 is captured by the image processing computer 60 via the image capturing interface 60c.

When the image of the semiconductor wafer is picked up by the ultraviolet light as described above, the automatic focus control is performed by the ultraviolet light autofocus control section 39. That is, the autofocus controller 39 for ultraviolet light detects whether or not the interval between the objective lens 38 for ultraviolet light and the semiconductor wafer matches the focal length of the objective lens 38 for ultraviolet light. Is the objective lens 38 for ultraviolet light.
Alternatively, the Z stage 18 is moved so that the inspection surface of the semiconductor wafer coincides with the focal plane of the ultraviolet light objective lens 38.

Here, the auto-focus control section 39 for ultraviolet light transmits an auto-focus control interface 61 to a control computer 61 arranged in the external unit 50.
e. Then, a control signal is sent from the control computer 61 to the ultraviolet light autofocus control section 39 via the autofocus control interface 61e. Automatic focusing of the ultraviolet light objective lens 38 by the ultraviolet light autofocus control unit 39 is performed based on this control signal.

Further, as described above, the clean air unit 4 is provided with two blowers 5a and 5b. These blowers 5a and 5b are connected to a control computer 61 arranged in the external unit 50 via an air volume control interface 61f. A control signal is sent from the control computer 61 to the blowers 5a and 5b of the clean air unit 4 via the air volume control interface 61f. Control of the number of rotations of the blowers 5a and 5b, switching on / off, and the like are performed based on this control signal.

Next, the optical unit 21 of the inspection apparatus 1
Will be described in more detail with reference to FIG. Here, the auto focus control units 35 and 3
The description of 9 will be omitted, and an optical system for illuminating the semiconductor wafer to be inspected and an optical system for imaging the semiconductor wafer to be inspected will be described.

As shown in FIG. 5, the optical unit 21
As an optical system for capturing an image of a semiconductor wafer with visible light, a halogen lamp 32 and an optical system 33 for visible light are used.
And a visible light objective lens 34.

The visible light from the halogen lamp 32 is guided by the optical fiber 40 to the visible light optical system 33.
The visible light guided to the visible light optical system 33 first passes through the two lenses 41 and 42 and enters the half mirror 43. Then, the visible light incident on the half mirror 43 is
The light is reflected by the half mirror 43 toward the objective lens 34 for visible light, and enters the semiconductor wafer via the objective lens 34 for visible light. Thereby, the semiconductor wafer is illuminated with the visible light.

Then, the image of the semiconductor wafer illuminated by the visible light is enlarged by the visible light objective lens 34,
The light passes through the half mirror 43 and the imaging lens 44 and is imaged by the visible light CCD camera 30. That is,
The reflected light from the semiconductor wafer illuminated by visible light
The light enters the visible light CCD camera 30 via the visible light objective lens 34, the half mirror 43, and the imaging lens 44.
The image is taken by the D camera 30. And C for visible light
An image of the semiconductor wafer (hereinafter, referred to as a visible image) captured by the CD camera 30 is sent to the image processing computer 60.

The optical unit 21 includes an ultraviolet laser light source 36, an ultraviolet optical system 37, and an ultraviolet objective lens 38 as an optical system for capturing an image of a semiconductor wafer with ultraviolet light. Have.

Ultraviolet light from the ultraviolet laser light source 36 is guided to the ultraviolet light optical system 37 by the optical fiber 45.
The ultraviolet light guided to the ultraviolet light optical system 37 first passes through the two lenses 46 and 47 and enters the half mirror 48. Then, the visible light incident on the half mirror 48 is
The light is reflected by the half mirror 48 toward the ultraviolet light objective lens 38 and is incident on the semiconductor wafer via the ultraviolet light objective lens 38. Thereby, the semiconductor wafer is illuminated by the ultraviolet light.

Then, the image of the semiconductor wafer illuminated with the ultraviolet light is enlarged by the ultraviolet light objective lens 38,
The light passes through the half mirror 48 and the imaging lens 49 and is imaged by the ultraviolet light CCD camera 31. That is,
The reflected light from the semiconductor wafer illuminated by ultraviolet light,
The light enters the ultraviolet light CCD camera 31 via the ultraviolet light objective lens 38, the half mirror 48, and the imaging lens 49, whereby the enlarged image of the semiconductor wafer is converted to the ultraviolet light CC.
The image is captured by the D camera 31. And UV light C
The image of the semiconductor wafer (hereinafter, referred to as an ultraviolet image) captured by the CD camera 31 is sent to the image processing computer 60.

In the inspection apparatus 1 as described above, an image of a semiconductor wafer can be imaged and inspected by ultraviolet light having a wavelength shorter than that of visible light. As compared with the case of performing classification, finer defects can be detected and classified.

In addition, the inspection apparatus 1 has both an optical system for visible light and an optical system for ultraviolet light, and inspects a semiconductor wafer at a low resolution using visible light and uses an ultraviolet light. Inspection of a semiconductor wafer with high resolution can be performed. Therefore, the inspection apparatus 1 detects and classifies large defects by inspecting a semiconductor wafer at low resolution using visible light, and inspects a semiconductor wafer at high resolution using ultraviolet light. It is also possible to detect and classify small defects.

In the inspection apparatus 1, the numerical aperture NA of the ultraviolet light objective lens 40 is preferably large.
For example, it is set to 0.9 or more. As described above, by using a lens having a large numerical aperture NA as the ultraviolet light objective lens 40, it is possible to detect a finer defect.

When a defect of a semiconductor wafer is composed of only irregularities without color information such as a scratch, the defect can hardly be seen with light having no coherence. On the other hand, when light having excellent coherence, such as laser light, is used, even when a defect such as a scratch has no color information and consists only of irregularities, light is generated in the vicinity of the irregularities. By interfering, the defect can be clearly seen. The inspection apparatus 1 uses an ultraviolet laser light source 36 that emits laser light in the ultraviolet region as a light source of ultraviolet light. Therefore, in the above inspection device 1,
Even a defect such as a scratch, which has no color information and consists only of irregularities, can be clearly detected. That is, in the inspection apparatus 1, the halogen lamp 3
Phase information, which is difficult to detect with visible light (incoherent light) from 2, can be easily detected using the ultraviolet laser (coherent light) from the ultraviolet laser light source 36.

Next, an example of a procedure for inspecting a semiconductor wafer by the inspection apparatus 1 will be described with reference to a flowchart of FIG. Note that the flowchart of FIG. 6 shows a procedure of a process after the semiconductor wafer to be inspected is set on the inspection stage 14. Further, the flowchart shown in FIG. 6 shows an example of a procedure when the defect is inspected by the inspection apparatus 1 and classified when the position of the defect on the semiconductor wafer is known in advance. Here, it is assumed that a number of similar device patterns are formed on a semiconductor wafer, and the detection and classification of defects are performed by using an image of a defective area (a defect image) and an image of another area (a reference image). ) Is taken and compared.

First, as shown in step S1-1, a defect position coordinate file is read into the control computer 61. Here, the defect position coordinate file is a file in which information relating to the position of the defect on the semiconductor wafer is described, and is created by measuring the position of the defect on the semiconductor wafer in advance by a defect detection device or the like. Then, here, the defect position coordinate file is read into the control computer 61.

Next, in step S1-2, the X stage 15 and the Y stage 16 are driven by the control computer 61 to move the semiconductor wafer to the defect position coordinates indicated by the defect position coordinate file. In the field of view of the objective lens 34 for visible light.

Next, in step S1-3, the visible light autofocus controller 35 is driven by the control computer 61 to perform automatic focus positioning of the visible light objective lens.

Next, in step S1-4, an image of the semiconductor wafer is captured by the visible light CCD camera 30, and the captured visible image is sent to the image processing computer 60. The visible image captured here is an image at the defect position coordinates indicated by the defect position coordinate file, that is, an image of a region where a defect is present (hereinafter, referred to as a defect image).

Next, in step S1-5, the X stage 15 and the Y stage 16 are driven by the control computer 61 to move the semiconductor wafer to the reference position coordinates, and the reference area of the semiconductor wafer is changed to the visible light objective lens. 3
4 so that it is within the field of view. Here, the reference region is a region other than the inspection target region of the semiconductor wafer, and is a region where a device pattern similar to the device pattern in the inspection target region of the semiconductor wafer is formed.

Next, in step S1-6, the visible light autofocus control unit 35 is driven by the control computer 61 to perform automatic focus positioning of the visible light objective lens.

Next, in step S1-7, an image of the semiconductor wafer is captured by the visible light CCD camera 30, and the captured visible image is sent to the image processing computer 60. Note that the visible image captured here is an image of a region where a device pattern similar to the device pattern in the inspection target region of the semiconductor wafer is formed (hereinafter, referred to as a reference image).

Next, at step S1-8, the image processing computer 60 compares the defect image captured at step S1-4 with the reference image captured at step S1-7, and detects a defect from the defect image. I do. If a defect is detected, the process proceeds to step S1-9. If a defect is not detected, the process proceeds to step S1-9.
Proceed to 11.

In step S1-9, the image processing computer 60 checks what the detected defect is and performs classification. If the defect can be classified, the process proceeds to step S1-10. If the defect cannot be classified, the process proceeds to step S1-11.

In step S1-10, the result of defect classification is stored. Here, the defect classification result is stored in, for example, a storage device connected to the image processing computer 60 or the control computer 61. Note that the defect classification result may be transferred to another computer connected to the image processing computer 60 or the control computer 61 via a network, and may be stored.

When the processing in step S1-10 is completed, it means that the classification of the defects in the semiconductor wafer has been completed, and the processing is completed. However, when there are a plurality of defects on the semiconductor wafer, the process may return to step S1-2 to detect and classify other defects.

On the other hand, if the defect cannot be detected in step S1-8, or if the defect cannot be classified in step S1-9, the process proceeds to step S1-11 and the subsequent steps. Defect detection and classification are performed by imaging at a resolution.

In that case, first, in step S1-11, the X stage 15 is controlled by the control computer 61.
Then, the Y stage 16 is driven to move the semiconductor wafer to the defect position coordinates indicated by the defect position coordinate file, so that the inspection target area of the semiconductor wafer falls within the field of view of the ultraviolet light objective lens 38.

Next, in step S1-12, the control computer 61 drives the ultraviolet auto-focus control section 39 to perform automatic focus positioning of the ultraviolet light objective lens.

Next, in step S1-13, an image of the semiconductor wafer is taken by the ultraviolet CCD camera 31, and the taken ultraviolet image is sent to the image processing computer 60. The ultraviolet image captured here is an image at the defect position coordinates indicated by the defect position coordinate file, that is, a defect image. In addition, imaging of the defect image here is performed with higher resolution than imaging using visible light, using ultraviolet light that is light having a shorter wavelength than visible light.

Next, in step S1-14, the control computer 61 drives the X stage 15 and the Y stage 16 to move the semiconductor wafer to the reference position coordinates. 38. Here, the reference area is
This is an area other than the inspection target area of the semiconductor wafer, in which a device pattern similar to the device pattern in the inspection target area of the semiconductor wafer is formed.

Next, in step S1-15, the control computer 61 drives the ultraviolet auto focus control section 39 to perform automatic focus positioning of the ultraviolet light objective lens.

Next, in step S1-16, an image of the semiconductor wafer is taken by the ultraviolet CCD camera 31, and the taken ultraviolet image is sent to the image processing computer 60. The ultraviolet image captured here is an image of a region where a device pattern similar to the device pattern in the inspection target region of the semiconductor wafer is formed, that is, a reference image. The imaging of the reference image here is performed at a higher resolution than when visible light is used by using ultraviolet light that is light having a shorter wavelength than visible light.

Next, in step S1-17, the image processing computer 60 compares the defect image captured in step S1-13 with the reference image captured in step S1-16, and detects a defect from the defect image. I do.
If a defect can be detected, step S1-1
Proceeding to step S8, if no defect is detected, proceeding to step S1-19.

In step S1-18, the image processing computer 60 checks what the detected defect is and performs classification. If the defect classification has been completed, the process proceeds to step S1-10, and the defect classification result is stored as described above. On the other hand, if the defect cannot be classified, the process proceeds to step S1-19.

In step S1-19, information indicating that the defect cannot be classified is stored. Here, information indicating that the defect cannot be classified is stored, for example, in a storage device connected to the image processing computer 60 or the control computer 61. Note that this information may be transferred to another computer connected to the image processing computer 60 or the control computer 61 via a network and stored.

According to the above-described procedure, first, an image picked up by the visible light CCD camera 30 is processed and analyzed to inspect the semiconductor wafer at a low resolution, and to detect a defect by visible light, When classification was not possible,
Next, the semiconductor wafer is inspected with high resolution by processing and analyzing the image captured by the ultraviolet CCD camera 31.

Here, a method of detecting a defect from a reference image and a defect image picked up by the CCD cameras 30 and 31 will be described with reference to FIG.

FIG. 7A shows an example of a reference area image in which a device pattern similar to the device pattern in the inspection target area is formed, that is, an example of the reference image. FIG. 7B shows an example of an image of a region to be inspected which is assumed to have a defect, that is, an example of a defect image.

When a defect is detected from such a reference image and a defect image, a device pattern is extracted from the reference image as shown in FIG. 7C based on color information, density information, and the like. Further, a difference image is obtained from the reference image and the defect image, and a portion having a large difference is extracted as a defect as shown in FIG.

Then, as shown in FIG.
An image obtained by superimposing the image of the device pattern extraction result shown in FIG. 7C and the image of the defect extraction result shown in FIG. 7D is obtained, and the rate at which the defect exists in the device pattern is determined. It is extracted as a feature value.

By the above-described method, the CCD camera 3
The image processing computer 60 processes and analyzes the reference image and the defect image captured by 0 and 31 to detect a defect and inspect a semiconductor wafer.

As described above, the inspection apparatus 1 first inspects the semiconductor wafer at a low resolution by processing and analyzing the image picked up by the visible light CCD camera 30, and inspects the defect by visible light. If the detection and classification cannot be performed, the semiconductor wafer is inspected at a high resolution by processing and analyzing the image captured by the ultraviolet CCD camera 31. It is possible to detect and classify finer defects as compared to the case of detecting and classifying defects using only visible light.

However, when imaging with low resolution using visible light, the area that can be imaged at a time is wider. If the defect is sufficiently large, inspection of the semiconductor wafer with low resolution using visible light is possible. Is more efficient. Therefore,
Rather than using ultraviolet light to inspect and classify defects from the beginning, as described above, inspecting and classifying defects using visible light first enables more efficient semiconductor wafers. Inspection can be performed.

In the inspection apparatus 1, as described above, the apparatus main body 10 for inspecting semiconductor wafers is installed inside the clean box 3, and clean air is supplied into the clean box 3 to provide a high cleanness. By maintaining the temperature in the environment, only the cleanness of the environment in which the inspection is performed is locally increased, and the inspection can be performed in a clean environment.

However, in the inspection apparatus 1 having such a structure, when the inspection of the semiconductor wafer is performed, as the inspection stage 14 and the transfer robot 23 are operated, the wear powder is stored in the clean box 3. Dust may be generated. When dust or the like generated in the clean box 3 adheres to the semiconductor wafer placed on the inspection stage 14 or the semiconductor wafer transported into the clean box 3 via the container 7, an appropriate Inspection will be hindered. Therefore, in the inspection apparatus 1, the dust and the like generated in the clean box 3 are quickly attached to the semiconductor wafer without adhering to the semiconductor wafer.
It is important to discharge to the outside.

In particular, in the inspection apparatus 1, for example, an extremely fine device pattern having a line width of 0.18 μm or less can be converted to a high resolution by using the ultraviolet laser light source 36 and the ultraviolet CCD camera 31 or the like. Since fine inspection is performed, fine dust and the like, which has not been a problem so far, can be a factor that hinders appropriate inspection.

Therefore, in the inspection apparatus 1, by appropriately controlling the air flow in the clean box 3, dusts and the like generated in the clean box 3 can be discharged to the outside of the clean box 3 including very fine ones. It is effectively discharged so that it does not adhere to the semiconductor wafer.

More specifically, in the inspection apparatus 1, the amount of clean air supplied from the clean air unit 4 into the clean box 3 is individually controlled for each of the blowers 5a and 5b. The airflow inside can be controlled freely.

The amount of clean air supplied into the clean box 3 from the clean air unit 4 is
As a method of controlling individually for each of a and 5b, for example, it is conceivable to individually adjust the rotation speed of the blowers 5a and 5b. In the inspection device 1, as described above, the blowers 5a,
5b is connected to the control computer 61 via the air volume control interface 61f. Then, the air volume control interface 61f is sent from the control computer 61.
By transmitting a control signal to the blowers 5a and 5b via the controller, the rotation speeds of the blowers 5a and 5b can be controlled.

Accordingly, in this inspection apparatus 1, the inspector inputs necessary instructions to the control computer 61 via the input device 53b, thereby individually adjusting the rotation speeds of the blowers 5a and 5b, and The amount of clean air supplied into the clean box 3 from 4 is
It can be controlled individually for each of the blowers 5a and 5b.

The air blown from the blowers 5a and 5b is
By passing through the high-performance air filter, the air is converted into clean air from which dust and the like are removed, and is sent as a downflow to each area in the clean box 3 located below these blowers 5a and 5b. here,
Assuming that the air volume from the blowers 5a and 5b is the same, the wind speed in each area in the clean box 3 located below the blowers 5a and 5b depends on the shape of the clean box 3 and the device in the clean box 3. The respective areas are different depending on the size of each area depending on the arrangement of the main body 10 and the like. Then, unexpected turbulence may occur due to the difference in wind speed in each region, and dust and the like generated in the clean box 3 may be rolled up and attached to the semiconductor wafer.

In the inspection device 1, the rotation speed of the blowers 5a and 5b is individually adjusted, and the amount of clean air supplied into the clean box 3 from the clean air unit 4 is individually adjusted for each of the blowers 5a and 5b. By controlling, for example, the wind speed in each area in the clean box 3 can be made uniform, so that it is possible to effectively prevent dust and the like from adhering to the semiconductor wafer.

To prevent dust and the like from adhering to the semiconductor wafer, clean air supplied into the clean box 3 is removed from the inspection stage 14 on which the semiconductor wafer is installed.
It is very effective to guide the wafer into the cassette 7b on which the semiconductor wafer is mounted. As described above, if clean air is guided on the inspection stage 14 on which the semiconductor wafer is installed or the cassette 7b on which the semiconductor wafer is mounted,
In addition to effectively preventing the turbulence that has taken up dust and the like from entering on the inspection stage 14 and the cassette 7b, it is also possible to temporarily prevent the semiconductor wafer or the cassette 7b installed on the inspection stage 14 Even when dust or the like adheres to the semiconductor wafer mounted in the box, the dust and the like can be removed and can be effectively discharged to the outside of the clean box 3.

In the inspection device 1, the rotation speed of the blowers 5a and 5b is individually adjusted, and the amount of clean air supplied from the clean air unit 4 into the clean box 3 is individually controlled for each of the blowers 5a and 5b. By doing so, the airflow in the clean box 3 can be appropriately controlled, so that clean air is guided to the inspection stage 14 on which the semiconductor wafer is installed or the cassette 7b on which the semiconductor wafer is mounted, and It is possible to effectively prevent dust and the like from adhering to the wafer.

The air flow in the clean box 3 can be visually confirmed by using an air flow visualization device. Therefore, the inspector can visually check the air flow in the clean box 3 while checking the clean air unit 4.
, The amount of clean air supplied into the clean box 3 can be individually controlled for each of the blowers 5a and 5b, so that the air flow in the clean box 3 can be controlled appropriately.

As a method of individually controlling the amount of clean air supplied from the clean air unit 4 into the clean box 3 for each of the blowers 5a and 5b, as shown in FIG. A partition plate 70 having an opening is provided on the side facing the clean box 3 and the opening ratio of the opening of the partition plate 70 is determined by the blower 5a,
It is conceivable to adjust individually for each position corresponding to 5b. In other words, the partition plate 7 at a position corresponding to the blower 5a
0, and the opening ratio of the opening of the partition plate 70 at a position corresponding to the blower 5b can be individually adjusted.
The blower 5a, 5b
Each can be controlled individually.

The partition plate 70 for separating the clean air unit 4 and the clean box 3 is formed by, for example, superposing punching metals 71 and 72 having a predetermined opening ratio. The partition plate 70 is provided with these punched metals 71, 72.
The aperture ratio can be changed by changing the way of overlapping. In the inspection device 1, the way of stacking the two punched metals 71 and 72 is individually adjusted at a position corresponding to the blower 5 a and a position corresponding to the blower 5 b, and the opening ratio of the opening of the partition plate 70 is adjusted. , Blowers 5a, 5
The adjustment is individually made for each position corresponding to b.

It is to be noted that a preferable value of the amount of clean air supplied into the clean box 3 from the position corresponding to the blower 5a and a preferable value of the amount of clean air supplied into the clean box 3 from the position corresponding to the blower 5b. If the value is known in advance, punching metal having an opening ratio that can secure a preferable air volume is disposed at a position corresponding to the blower 5a and a position corresponding to the blower 5b, and this is also used as the partition plate 70. Good.

In the above description, the example in which the clean air unit 4 includes the two blowers 5a and 5b has been described. However, the number of blowers may be determined according to the size and shape of the clean box 3. It may be configured to include a blower. In this case, the clean air unit 4
, The amount of clean air supplied into the clean box 3 is individually controlled for each blower.

Further, in this inspection apparatus 1, as shown in FIGS. 2 and 9, in order to guide the clean air supplied into the clean box 3 onto the inspection stage 14 on which the semiconductor wafer is installed, an inspection is performed. An opening area 80 is provided on the side surface of the clean box 3 located on the side of the use stage 14. FIG. 9 is a side view showing the appearance of the clean unit 2 viewed from the direction of arrow A2 in FIG.

More specifically, for example, the inspection stage 14
A punching metal having a predetermined opening ratio is fitted into a side surface portion of the clean box 3 located on the side of the clean box 3, and a portion where the punching metal is fitted is an opening region 80. As described above, the inspection apparatus 1 supplies the clean box 3 as a downflow from the clean air unit 4 by providing the opening area 80 on the side surface of the clean box 3 located on the side of the test stage 14. A part of the clean air that has been
After passing through the upper part, it can be guided to an opening area 80 provided on the side thereof, and can be discharged to the outside of the clean box 3 from this opening area 80.

In order to properly guide the clean air supplied into the clean box 3 onto the inspection stage 14 on which the semiconductor wafer is installed, the inspection apparatus 1 shown in FIG.
As shown in FIG. 9, an overhang 81 is provided on the side surface of the clean box 3 so as to project inward, and the air chamber in the clean box 3 is separated at the lower end of the inspection table 14. Have been. The overhang portion 81 is made of punched metal having a predetermined opening ratio, and guides a part of the clean air supplied into the clean box 3 as a downflow from the clean unit 4 to the lower end portion of the clean box 3 and other parts. Of the inspection table 14
Guide up. The tip of the overhang 81 is separated from the apparatus main body 10 with a slight gap. This is because vibration generated in the clean box 3 is not transmitted to the apparatus main body 10. In the inspection apparatus 1, as described above, even a slight vibration interferes with the inspection. Therefore, such a measure against the vibration is very effective.

As described above, the clean air supplied from the clean air unit 4 is guided onto the inspection stage 14 on which the semiconductor wafer is installed, and is passed through the inspection stage 14, thereby providing a clean box. It is possible to effectively prevent the turbulent air that has wound up the dust and the like in 3 from entering the inspection stage 14.

If the clean air supplied from the clean air unit 4 is guided onto the inspection stage 14 on which the semiconductor wafer is installed and is passed through the inspection stage 14, the inspection stage 14 Even when dust or the like adheres to the installed semiconductor wafer, the dust and the like can be removed from the semiconductor wafer by clean air and can be appropriately discharged to the outside of the clean box 3 through the opening region 80. .

In the inspection apparatus 1, the opening area 80 and the overhang 81 provided on the side of the inspection stage 14 are formed by laminating two punching metals like the partition plate 70 described above. One of the punching metals may be movable. In this case, the opening ratio of the opening region 80 and the overhang portion 81 can be freely changed, which is very advantageous in controlling the airflow in the clean box 3.

Further, in this inspection apparatus 1, in order to guide the clean air supplied into the clean box 3 into the cassette 7b on which the semiconductor wafer is mounted, as shown in FIG. An opening region 90 is provided in a side surface portion located on a side of a place where the is accommodated.

More specifically, for example, the clean box 3
A punching metal having a predetermined opening ratio is fitted into a side surface portion located at a side of a place where the cassette 7b is accommodated, and a portion where the punching metal is fitted is an opening region 90. As described above, the inspection device 1 is provided with the opening area 90 on the side surface located on the side of the place where the cassette 7b of the clean box 3 is accommodated, so that the clean box 3 A part of the clean air supplied to the inside is passed through the cassette 7b transferred into the clean box 3 and guided to an open area 90 provided on the side thereof. Can be discharged to the outside.

In the inspection apparatus 1, as shown in FIG. 10, in order to appropriately guide the clean air supplied into the clean box 3 into the cassette 7b on which the semiconductor wafer is mounted, the clean box 3 In the vicinity of the location where the cassette 7b is accommodated, an inclined guide portion 91 inclined toward the location where the cassette 7b is accommodated is provided.

Specifically, an installation plate 92 on which the transfer robot 23 and the pre-aligner 24 are installed is placed on the support base 11 of the apparatus main body 10 at the same height position as the overhang portion 81 provided on the clean box 3. At one end of the installation plate 92, there is provided an inclined guide portion 91 which is inclined toward a place where the cassette 7b is stored. Note that FIG.
FIG. 3 is a perspective view showing a state in which the apparatus main body 10 in the clean box 3 is viewed from the side where the elevator 22, the transfer robot 23, the pre-aligner 24 and the like are provided.

As described above, by providing the inclined guide portion 91 which is inclined toward the place where the cassette 7b is housed near the place where the cassette 7b is housed in the clean box 3, the inside of the clean box 3 is provided. The supplied clean air can be guided by the inclined guide portion 91 and appropriately guided into the cassette 7b in which the semiconductor wafer is mounted.

As described above, the clean air supplied from the clean air unit 4 is guided into the cassette 7b on which the semiconductor wafer is mounted, and is allowed to pass through the cassette 7b. It is possible to effectively prevent the turbulent air that has been wound up from entering the cassette 7b.

Further, the clean air supplied from the clean air unit 4 is supplied to the cassette 7 on which the semiconductor wafer is mounted.
b, and pass through the cassette 7b, even if dust or the like adheres to the semiconductor wafer mounted in the cassette 7b, the dust or the like is removed from the semiconductor wafer by clean air. Then, it is possible to appropriately discharge the outside of the clean box 3 through the opening region 90.

In the inspection apparatus 1, the opening area 90 provided on the side of the clean box 3 where the cassette 7b is accommodated is formed by laminating two sheets of punching metal like the partition plate 70 described above. In combination, one of the punching metals may be made movable. In this case, the opening ratio of the opening region 90 can be freely changed, which is very advantageous in controlling the airflow in the clean box 3.

Further, in this inspection apparatus 1, as shown in FIG. 10, an area where the inspection table 14 of the apparatus main body 10 is disposed, an elevator 22, a transfer robot 23, a pre-aligner 24, and the like are disposed. Between the regions, a partition wall 93 that partitions these regions is provided.

The partition wall 93 removes fine dust and the like generated in the area where the inspection table 14 is provided, from the elevator 2.
2 and the transfer robot 23, the pre-aligner 24, etc., are prevented from entering the area where they are disposed.
Specifically, the support member 20 supporting the optical unit 21
Is formed integrally at the lower end of the upper surface at a predetermined height, and the raised portion serves as a partition wall 93.

[0159] As described above, the inspection apparatus 1 has the
0 between the area where the inspection table 14 is disposed and the area where the elevator 22, the transport robot 23, the pre-aligner 24 and the like are disposed.
When the clean air supplied from the clean air unit 4 is introduced into the cassette 7b on which the semiconductor wafer is mounted, fine dust and the like generated in the area where the inspection table 14 is provided by providing the clean air unit 4. Can be effectively prevented from entering the cassette 7 together with clean air.

Further, in this inspection apparatus 1, when the opening ratio of the clean box 3 becomes high, for example, when the window 3a of the clean box 3 is opened for maintenance or the like, the inside and outside of the clean box 3 are removed. The wind speed of the clean air is controlled based on the differential pressure gauge 56 for detecting the pressure difference so as to maintain the positive pressure. Further, in the inspection apparatus 1, the clean air is supplied to the semiconductor wafer, for example, as described above. The following control is performed in order to appropriately control the airflow such as guiding the airflow into the cassette 7b. Hereinafter, this control will be described with reference to FIG.

First, in the inspection apparatus 1, at the start of the start of the apparatus, the wind speed inside the clean box 3 is measured by the anemometer 55, and settings are made so that the wind speed of the clean air is optimized (step). S10-1). At this time, the window 3a of the clean box 3 is kept closed. Subsequently, based on the measurement value of the differential pressure gauge 56, it is confirmed whether or not the state is at least a positive pressure (step S10-2). Normally, if the wind speed is increased by closing the window 3a, the inside of the clean box 3 will be in a positive pressure state. However, if it is not a positive pressure state, the cause may be confirmed or the wind speed may be further increased. Try to maintain a positive pressure.
Subsequently, the measured value of the differential pressure gauge 56 and the blower 5
The rotation speeds a and 5b are stored as initial setting values (step S10-3). The above steps S10-1 to 10-
3 is the initial setting operation.

Here, the optimum wind speed at the time of the initial setting operation differs for each inspection apparatus. For example, in the inspection device 1, as described above, the speed is such that dust and the like generated in the clean box 3 can be quickly discharged including fine particles, and the wind speed of the two blowers 5a and 5b is further increased. The wind speed is set so that turbulence does not occur due to the difference. In addition, in this inspection apparatus 1, in order to prevent dust and the like from adhering to the semiconductor wafer,
Inspection stage 1 optimally guided into cassette 7b on which semiconductor wafers are mounted, and on which semiconductor wafers are mounted
4 so that the wind speed can be optimally guided on top.

The control of the wind speed at the time of the initial setting may be performed by controlling the rotation speed of the blowers 5a and 5b by the control computer 61, or, for example, by visually observing the measured value of the anemometer 55. Alternatively, the opening ratio of the punched metal may be changed without using the control computer 61. In addition, the anemometer 55
It is used only during this initial setting. Therefore, the anemometer 55 may be removed after the initial setting.

The initial setting operation may be performed at regular intervals, for example, when the inspection apparatus 1 is put into a factory, or when the inspection apparatus 1 is operated for a predetermined time (for example, 100 hours or 1000 hours). May be performed after calibration, or at the time of calibration of the entire inspection apparatus 1.

Subsequently, during the normal operation after the initial setting (the normal operation referred to here is not only during the inspection of the semiconductor wafer but also in a state where the cleanness in the clean box 3 is maintained. For example, at the time of maintenance, etc.), the wind speed based on the initially set wind speed is varied based on the pressure value from the differential pressure gauge 56 (step S10-4). That is, based on the pressure value from the differential pressure gauge 56, the inspection device 1 varies the initially set rotational speeds of the blowers 5a and 5b to control the wind speed. Specifically, if the pressure value of the differential pressure gauge 56 is an initial setting value, the rotation speed of the blowers 5a and 5b is set to the initial setting value, and if the pressure inside the clean box 3 becomes lower than the initial setting value, the blower The wind speed is varied such that the rotational speeds of 5a and 5b are higher than the initial set value. It should be noted that the pressure value from the differential pressure gauge 56 always fluctuates. Therefore, the pressure value is not changed in the case of a minute change. Good. In addition, since the inside of the clean box 3 only needs to maintain at least the positive pressure, it may be controlled to increase the initially set wind speed when the pressure at the boundary where the positive pressure can be maintained. .

As described above, in the inspection apparatus 1, not only the internal state of the clean box is simply set to the positive pressure state, but also the wind speed of the internal air is optimal for the inspection apparatus. State. Therefore, in this inspection apparatus 1, it is possible to prevent the inflow of dust and the like from the outside, and to allow clean air to flow into the clean box 3 at a predetermined wind speed or more, so that fine dust and the like adhere to the inspection object. Can be effectively prevented.

In the above description, the inspection apparatus 1 to which the present invention is applied has been used for checking what the defect is in the semiconductor wafer. However, the use of the inspection apparatus 1 according to the present invention can be used for purposes other than the defect identification of the semiconductor wafer. That is, the inspection apparatus 1 according to the present invention can be used, for example, to inspect whether a device pattern formed on a semiconductor wafer is formed in an appropriate shape as a desired pattern. Further, the use of the inspection device 1 according to the present invention is not limited to inspection of a semiconductor wafer, and the inspection device 1 according to the present invention is widely applicable to inspection of fine patterns. It is also effective for inspection of flat panel displays on which various patterns are formed.

[0168]

As described in detail above, in the inspection apparatus according to the present invention, the wind speed of the clean air flowing inside the clean box is set to a positive pressure and the optimum wind velocity for the inspection apparatus. Initial settings are performed as follows. Then, after performing the initial setting, the wind speed set in the initial setting state is varied according to the internal / external air pressure difference.

As a result, in the inspection apparatus according to the present invention, it is possible to prevent the inflow of dust and the like from the outside, and to allow clean air to flow into the clean box at a predetermined wind speed or more, thereby enabling fine dust and the like to flow. Can be effectively prevented from adhering to the inspection object.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of an inspection apparatus to which the present invention is applied.

FIG. 2 is a diagram showing a state in which an apparatus main body disposed inside a clean box of the inspection apparatus is viewed from a direction of an arrow A1 in FIG.

FIG. 3 is a plan view schematically showing an apparatus main body of the inspection apparatus as viewed from above.

FIG. 4 is a block diagram showing a configuration example of the inspection device.

FIG. 5 is a diagram showing a configuration example of an optical system of an optical unit of the inspection device.

FIG. 6 is a flowchart showing an example of a procedure when a semiconductor wafer is inspected by the inspection apparatus.

FIG. 7 is a diagram for explaining a method of detecting a defect from a reference image and a defect image.

FIG. 8 is a perspective view schematically showing a state where a clean box and a clean air unit of the inspection apparatus are separated.

FIG. 9 is a side view showing a state where the clean box of the inspection apparatus is viewed from the direction of arrow A2 in FIG.

FIG. 10 is a perspective view of an apparatus main body of the inspection apparatus.

FIG. 11 is a flowchart illustrating a wind speed control procedure of the inspection device.

[Explanation of symbols]

Reference Signs List 1 inspection device, 2 clean unit, 3 clean box, 4 clean air unit, 5a, 5b blower, 10 device body, 14 inspection stage, 21 optical unit, 22 elevator, 23 transport robot, 24 pre-aligner, 30 for visible light CCD camera, 31 ultraviolet CCD camera, 32 halogen lamp, 33 visible light optical system, 34 visible light objective lens, 36 ultraviolet laser light source, 37 ultraviolet light optical system,
38 Objective lens for ultraviolet light, 50 External unit, 5
1,52 display device, 53 input device, 55 anemometer,
56 Differential pressure gauge, 60 Image processing computer, 61
Control computer, 70 Partition plate, 71, 72 Punched metal, 80 Open area, 81 Overhang, 90
Opening area, 91 Incline guide section, 92 Installation plate, 93
Partition wall

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F055 AA39 BB06 BB11 CC60 DD20 EE40 FF31 4M106 AA01 BA05 BA08 BA20 CA38 CA39 CA70 DB04 DB07 DB08 DJ04 DJ05 DJ06 DJ11 DJ24 DJ38 DJ40

Claims (1)

[Claims] 1. An apparatus main body for inspecting an object to be inspected, a clean box accommodating the apparatus main body therein, an air supply unit for supplying clean air to the inside of the clean box, and the clean box A wind speed measuring unit for measuring a wind speed of clean air supplied to the inside of the clean box; a pressure measuring unit for measuring a differential pressure between the inside and the outside of the clean box; A wind speed control unit that controls a wind speed, wherein the wind speed control unit is configured to control the clean air inside the clean box based on the detection result by the wind speed measurement unit in a state where the pressure inside the clean box is at least a positive pressure. The wind speed is initially set to a predetermined wind speed, and after this initial setting, the initial value is set in accordance with the pressure difference between the inside and outside of the clean box measured by the pressure measuring unit. An inspection apparatus characterized by varying a wind speed set in a set state.