JP4172124B2 - Inspection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
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]
[Prior 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. A semiconductor device in which such a defect has occurred becomes a defective device and reduces the yield.
[0003]
Therefore, in order to stabilize the yield of the production line at a high level, it is necessary to detect defects caused by dust or scratches at an early stage, identify the cause, and take effective measures for the production equipment and production process. preferable.
[0004]
Therefore, when a defect is found, an inspection apparatus is used to investigate what the defect is and classify it to identify the facility or process that caused the defect. Here, the inspection apparatus that examines what the defect is is like an optical microscope, and the defect is magnified to identify what the defect is.
[0005]
[Problems to be solved by the invention]
By the way, in an inspection apparatus that performs such an inspection, a semiconductor wafer on which a predetermined device pattern is formed is placed on a stage, and the stage on which the semiconductor wafer is placed is moved to operate the semiconductor wafer. To the inspection target position.
[0006]
Further, in this inspection apparatus, in order to guide the semiconductor wafer to a predetermined inspection target position, while detecting the position of the stage on which the semiconductor wafer is placed, the stage is moved to a predetermined position based on the detected signal. A so-called positioning servo is performed to move to the inspection target position. In this positioning servo, as shown in FIG. 16, the stage is moved into the 0 count range where the predetermined inspection target position P is located, and then the servo loop is turned on within this 0 count range. The stage is guided to the inspection target position P.
[0007]
However, in the positioning servo, when the stage is located near the boundary with ± 1 count adjacent to 0 count, the servo gain is high. However, it may be accelerated to pass the inspection target position P and jump into the +1 count side on the opposite side. For this reason, in the inspection apparatus, the stage may stop at a position shifted by several counts from the inspection target position P, or the stage may be slightly vibrated without converging on the inspection target position P.
[0008]
Therefore, in the conventional inspection apparatus, the stage on which the semiconductor wafer is placed cannot be accurately positioned at a predetermined inspection target position, which may cause a significant decrease in inspection capability.
[0009]
In particular, the device pattern formed on the semiconductor wafer is miniaturized as the semiconductor device is highly integrated, and it has become increasingly difficult to accurately position the semiconductor wafer at a predetermined inspection target position. As shown in FIG. 16, the width of each count in the positioning servo is about 50 nm.
[0010]
Further, since the inspection apparatus inspects the semiconductor wafer on which such a fine device pattern is formed, even the slight vibration of the stage described above becomes a serious obstacle to the inspection.
[0011]
Therefore, the present invention has been proposed in view of such a conventional situation, and when a stage on which an inspection object is placed is moved, the stage is accurately positioned at a predetermined inspection target position. An object of the present invention is to provide an inspection apparatus capable of performing the above.
[0012]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventor adds a sliding resistance to the drive shaft of the stage, and adjusts the sliding resistance applied to the drive shaft, thereby inspecting the object to be inspected. It has been found that the stage on which can be placed can be accurately positioned at a predetermined inspection target position.
[0013]
That is, the inspection apparatus according to the present invention has been created based on the above knowledge, and is controlled while controlling the stage on which the inspection object is placed and the stage on which the inspection object is placed. Stage moving means for moving to the position to be inspected, and sliding contact resistance adding means for adjusting the sliding contact resistance to the drive shaft of the stage moving means in an adjustable manner. A sliding contact member that is in sliding contact with the peripheral surface; and a sliding contact resistance adjusting unit that adjusts a contact pressure of the sliding contact member with respect to the peripheral surface of the drive shaft. MC nylon having a slidable contact surface portion that slidably covers, an opening provided by cutting out a part of the slidable contact surface portion, and a plurality of grooves that divide the entire circumference of the slidable contact surface portion at a predetermined interval Or the sliding contact resistance adjusting means is the width of the opening of the sliding contact member. By changing, it is characterized in adjusting the contact pressure against the peripheral surface of the drive shaft.
[0014]
In this inspection apparatus, since the sliding contact resistance adding means adds a predetermined sliding contact resistance to the drive shaft of the stage moving means, the stage moved by the stage moving means is accurately placed at a predetermined inspection target position. Can be positioned. Further, by making the sliding resistance added to the drive shaft adjustable, the sliding resistance added to the drive shaft can be easily adjusted.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0016]
The appearance of an inspection apparatus to which the present invention is applied is shown in FIG. This inspection apparatus 1 is for inspecting a semiconductor wafer on which a predetermined device pattern is formed, and when a defect is found in a device pattern formed on a semiconductor wafer, what is the defect? It classifies by examining.
[0017]
As shown in FIG. 1, the inspection apparatus 1 includes a clean unit 2 for keeping the 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 into a hollow box shape, and a clean air unit 4 integrally provided on the upper portion of the clean box 3.
[0018]
The clean box 3 is provided with a window portion 3a at a predetermined location so that an inspector can visually recognize the inside of the clean box 3 from the window portion 3a.
[0019]
The clean air unit 4 is for supplying clean air into the clean box 3, and includes two blowers 5a and 5b respectively disposed at different positions on the upper portion of the clean box 3, and these blowers 5a and 5b. And an air filter (not shown) disposed between the clean box 3 and the clean box 3. The air filter is, for example, a high-performance air filter such as a HEPA filter (High Efficiency Particulate Air Filter) or a ULPA filter (Ultra Low Penetration Air Filter). The clean air unit 4 is configured to remove dust and the like in the air blown by the blowers 5a and 5b with a high-performance air filter and supply the clean box 3 as clean air.
[0020]
Moreover, in this clean unit 2, the air flow in the clean box 3 is controlled by individually controlling the air volume of clean air supplied from the clean air unit 4 into the clean box 3 for each of the two blowers 5a and 5b. It is possible to control appropriately. 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 in accordance with the size and shape of the clean box 3, and includes three or more blowers. It may be configured. In this case, in the inspection apparatus 1, the air volume of clean air supplied from the clean air unit 4 into the clean box 3 is individually controlled for each blower.
[0021]
The clean unit 2 has a structure in which the clean box 3 is supported on the floor board by the support legs 6 and the lower end thereof is opened. In the clean unit 2, 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. In addition, an opening region 3 b is provided at a predetermined location on the side surface of the clean box 3, and air supplied from the clean air unit 4 into the clean box 3 is provided on the side surface of the clean box 3. Also, the air is discharged from the open area 3b.
[0022]
As described above, the clean unit 2 constantly supplies clean air from the clean air unit 4 into the clean box 3 and discharges air circulated in the clean box 3 as an air current to the outside of the clean box 3. Let As a result, dust or the like generated in the clean box 3 is discharged to the outside of the clean box 3 together with this air, and the internal environment of the clean box 3 is kept at a very high cleanness of, for example, about class 1. . Further, in the clean box 3, the internal atmospheric pressure is always kept at a positive pressure in order to prevent air including dust from entering the inside from the outside.
[0023]
In this inspection apparatus 1, as shown in FIG. 2, an apparatus main body 10 is accommodated in a clean box 3, and a semiconductor in which a predetermined device pattern is formed by the apparatus main body 10 in the clean box 3. The wafer is inspected. Here, the semiconductor wafer to be inspected is transferred into a predetermined sealed container 7 and transferred to the inside of the clean box 3 through the container 7. 2 is a side view showing a state in which the apparatus main body 10 disposed inside the clean box 3 is viewed from the direction of the arrow A1 in FIG.
[0024]
The container 7 includes a bottom portion 7a, a cassette 7b fixed to the bottom portion 7a, and a cover 7c that is detachably engaged with the bottom portion 7a and covers the cassette 7b. The semiconductor wafers to be inspected are mounted on the cassette 7b so that a plurality of semiconductor wafers are overlapped with each other at a predetermined interval, and are sealed by the bottom 7a and the cover 7c.
[0025]
When inspecting a semiconductor wafer, first, the container 7 in which the semiconductor wafer is placed is installed in a container installation space 8 provided at a predetermined position of the clean box 3. The container installation space 8 is arranged such that the upper surface of a lift 22a of an elevator 22 to be described later faces the outside of the clean box 3, and the bottom 7a of the container 7 is positioned on the lift 22a of the elevator 22. As shown, it is installed in the container installation space 8.
[0026]
When the container 7 is installed in the container installation space 8, the engagement between the bottom 7a of the container 7 and the cover 7c is released. 2 is moved down in the direction of arrow B in FIG. 2, the bottom 7a and the cassette 7b of the container 7 are separated from the cover 7c and moved into the clean box 3. As a result, the semiconductor wafer that is the object to be inspected is transferred into the clean box 3 without being exposed to the outside air.
[0027]
When the semiconductor wafer is transferred into the clean box 3, a semiconductor robot to be inspected is taken out from the cassette 7b and inspected by a transfer robot 23 described later.
[0028]
As described above, since the inspection apparatus 1 inspects the semiconductor wafer inside the clean box 3 maintained at a high degree of cleanness, dust or the like adheres to the semiconductor wafer at the time of inspection. Inconveniences such as inhibition 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 through the container 7. If only the inside of the container 7 is kept clean enough, 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 apparatus 1 is installed. .
[0029]
Thus, by increasing only the degree of cleanliness at a necessary place locally, it is possible to achieve a high degree of cleanness and to significantly reduce the cost for realizing a clean environment. As a mechanical interface between the sealed container 7 and the clean box 3, a so-called SMIF (standard mechanical interface) is suitable. In this case, a so-called SMIF-POD is used as the sealed container 7. .
[0030]
In addition, 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. The external unit 50 is installed outside the clean box 3 and is supported on the floor board by support legs 51. In the external unit 50, a display device 52 for displaying an image obtained by imaging a semiconductor wafer, a display device 53 for displaying various conditions at the time of inspection, an instruction input to the device main body 10 and the like are performed. The input device 54 and the like are also arranged. An inspector who inspects the semiconductor wafer inputs necessary instructions from the input device 54 disposed in the external unit 50 while looking at the display devices 52 and 53 disposed in the external unit 50, and inspects the semiconductor wafer. I do.
[0031]
Next, the apparatus main body 10 disposed in the clean box 3 will be described in detail.
[0032]
The apparatus main body 10 includes a support base 11 as shown in FIG. The support base 11 is a base for supporting each mechanism of the apparatus main body 10. A support leg 12 is attached to the bottom of the support base 11, and each mechanism provided on the support base 11 and the support base 11 is supported on the floor plate independently of the clean box 3 by the support leg 12. It has a structure.
[0033]
An inspection stage 14 on which a semiconductor wafer to be inspected is placed is provided on the support table 11 via a vibration isolation table 13.
[0034]
The vibration isolation table 13 is for suppressing vibration from the floor, vibration generated when the inspection stage 14 is moved, and the stone surface plate 13a on which the inspection stage 14 is installed. And a plurality of movable legs 13b that support the surface plate 13a. When the vibration is generated, the vibration isolation table 13 detects the vibration to drive the movable leg 13b, and the vibration of the stone surface plate 13a and the inspection stage 14 installed on the stone surface plate 13a. Will be canceled promptly.
[0035]
Since this inspection apparatus 1 inspects a semiconductor wafer on which a fine device pattern is formed, even a slight vibration may be an obstacle to the inspection. In particular, since this inspection apparatus 1 performs inspection with high resolution using ultraviolet light, the influence of vibration is likely to appear greatly. Therefore, in this inspection apparatus 1, by installing the inspection stage 14 on the vibration isolation table 13, even if a slight vibration occurs in the inspection stage 14, this vibration is quickly canceled out and the vibration is reduced. By suppressing the influence, the inspection capability when performing inspection with high resolution using ultraviolet light is improved.
[0036]
In order to stably install the inspection stage 14 on the vibration isolation table 13, it is desirable that the center of gravity of the vibration isolation table 13 is at a position that is somewhat low. Therefore, in the inspection apparatus 1, a notch 13c is provided at the lower end of the stone surface plate 13a, and the movable leg 13b supports the stone surface plate 13a at the notch 13c so that the vibration isolation table 13 is provided. The center of gravity is lowered.
[0037]
Note that vibrations and the like generated when the inspection stage 14 is moved can be predicted to some extent in advance. If such vibration is predicted in advance and the vibration isolation table 13 is operated, vibration generated in the inspection stage 14 can be prevented in advance. Therefore, it is desirable that the inspection apparatus 1 operate the vibration isolation table 13 by predicting in advance vibrations or the like generated when the inspection stage 14 is moved.
[0038]
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 moving the semiconductor wafer to a predetermined inspection target position.
[0039]
Specifically, the inspection stage 14 includes an X stage 15 installed on the vibration isolation table 13, a Y stage 16 installed on the X stage 15, and 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.
[0040]
The X stage 15 and the Y stage 16 are stages that move in the horizontal direction, and the X stage 15 and the Y stage 16 move the semiconductor wafers to be inspected in directions orthogonal to each other, thereby changing the device pattern to be inspected. It leads to a predetermined inspection position.
[0041]
The θ stage 17 is a so-called rotation stage and is for rotating the 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 with respect to the screen.
[0042]
The Z stage 18 is a stage that moves in the vertical direction, and is for adjusting the height of the stage. During the inspection of the semiconductor wafer, the stage height is adjusted by the Z stage 18 so that the inspection surface of the semiconductor wafer has an appropriate height.
[0043]
The suction plate 19 is for sucking and fixing a 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 this suction plate 19 By adsorbing, unnecessary movement is suppressed.
[0044]
Also, the vibration isolation table 13 Above, an optical unit 21 supported by a support member 20 so as to be positioned on the inspection stage 14 is disposed. The optical unit 21 is for capturing an image of a semiconductor wafer during inspection of the semiconductor wafer. The optical unit 21 has a function of capturing an image of the semiconductor wafer to be inspected with low resolution using visible light, and an image of the semiconductor wafer to be inspected with high resolution using ultraviolet light. It has the function to perform.
[0045]
Further, as shown in FIGS. 2 and 3, an elevator 22 is provided on the support base 11 to take out a cassette 7 b mounted with a semiconductor wafer to be inspected from the container 7 and move it into the clean box 3. ing. Further, as shown in FIG. 3, on the support base 11, a transfer robot 23 for transferring the semiconductor wafer, and centering and phase out before placing the semiconductor wafer on the inspection stage 14. A pre-aligner 24 is provided. FIG. 3 is a plan view schematically showing the apparatus main body 10 disposed in the clean box 3.
[0046]
The elevator 22 has a lifting platform 22a that is moved up and down. The container 7 is installed in the container installation space 8 of the clean box 3, and the engagement between the bottom 7a of the container 7 and the cover 7c is released. When the lifting platform 22a is lowered, the bottom 7a of the container 7 and the cassette 7b fixed thereto are moved into the clean box 3.
[0047]
The transfer robot 23 has an operation arm 23b provided with a suction mechanism 23a at the tip, and moves the operation arm 23b to suck the semiconductor wafer by the suction mechanism 23a provided at the tip. However, the semiconductor wafer is transported in the clean box 3.
[0048]
The pre-aligner 24 performs phase alignment and center alignment of the semiconductor wafer with reference to an orientation flat and a notch formed in advance on the semiconductor wafer. The inspection apparatus 1 improves the inspection efficiency by performing phase alignment and the like by the pre-aligner 24 before placing the semiconductor wafer on the inspection stage 14.
[0049]
When installing the semiconductor wafer on the inspection stage 14, first, the bottom portion 7 a and the cassette 7 b of the container 7 are moved into the clean box 3 by the elevator 22. Then, a semiconductor wafer to be inspected is selected from a plurality of semiconductor wafers mounted on the cassette 7b, and the selected semiconductor wafer is taken out from the cassette 7b by the transfer robot 23.
[0050]
The semiconductor wafer taken out from the cassette 7 b is transferred to the pre-aligner 24 by the transfer robot 23. The semiconductor wafer transferred to the pre-aligner 24 is phased and centered by the pre-aligner 24. Then, the phase-adjusted and center-adjusted semiconductor wafer is transferred to the inspection stage 14 by the transfer robot 23 and placed on the suction plate 19 for inspection.
[0051]
When the semiconductor wafer to be inspected is transferred to the inspection stage 14, the next semiconductor wafer to be inspected is taken out from the cassette 7 b by the transfer robot 23 and transferred to the pre-aligner 24. Then, while the semiconductor wafer previously transported to the inspection stage 14 is being inspected, the semiconductor wafer to be inspected next is phased out and centered out. Then, when the inspection of the semiconductor wafer previously transferred to the inspection stage 14 is completed, the semiconductor wafer to be inspected next is quickly transferred to the inspection stage 14.
[0052]
In the inspection apparatus 1, as described above, before the semiconductor wafer to be inspected is transferred to the inspection stage 14, the phase alignment and centering are performed in advance by the pre-aligner 24, so that the semiconductor wafer of the inspection stage 14 is aligned. The time required for positioning can be shortened. In the inspection apparatus 1, the semiconductor wafer to be inspected next is taken out from the cassette 7 b using the time during which the semiconductor wafer previously transferred to the inspection stage 14 is inspected, and the phase alignment by the pre-aligner 24 is performed. By performing the centering operation, the overall time can be shortened and the inspection can be performed efficiently.
[0053]
By the way, in this inspection apparatus 1, as shown in FIG. 3, the elevator 22, the transfer robot 23, and the pre-aligner 24 are installed on the support base 11 so as to be aligned on a straight line. The respective installation positions are determined such that the distance L1 between the elevator 22 and the transport robot 23 and the distance L2 between the transport robot 23 and the pre-aligner 24 are substantially equal. Further, the inspection stage 14 is arranged in a direction substantially orthogonal to the direction in which the elevator 22 and the pre-aligner 24 are arranged as viewed from the transfer robot 23.
[0054]
Since the inspection apparatus 1 is arranged as described above, the inspection apparatus 1 can quickly and accurately carry a semiconductor wafer as an inspection object.
[0055]
That is, in this inspection apparatus 1, since the distance L1 between the elevator 22 and the transfer robot 23 and the distance L2 between the transfer robot 23 and the pre-aligner 24 are substantially equal, the transfer robot 23 Operation arm The semiconductor wafer taken out from the cassette 7b can be transferred to the pre-aligner 24 without changing the length of 23b. Therefore, in this inspection apparatus 1, the transfer robot 23 is Operation arm Since an error or the like generated when the length of 23b is changed does not become a problem, the operation of transporting 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 from the cassette 7b to the pre-aligner 24 only by a linear movement. it can . Therefore, in this inspection apparatus 1, the operation of transporting the semiconductor wafer to the pre-aligner 24 can be performed very accurately and quickly.
[0056]
Furthermore, in this inspection apparatus 1, since the inspection stage 14 is positioned in a direction substantially orthogonal to the direction in which the elevators 22 and the pre-aligner 24 are arranged as viewed from the transfer robot 23, the transfer robot The semiconductor wafer 23 can be transported to the inspection stage 14 by the 23 moving linearly. Therefore, in this inspection apparatus 1, the operation of transporting the semiconductor wafer to the inspection stage 14 can be performed very accurately and quickly. In particular, since the inspection apparatus 1 inspects a semiconductor wafer on which a fine device pattern is formed, it is necessary to carry and position the semiconductor wafer as an inspection object very accurately. Is very effective.
[0057]
In the inspection apparatus 1, tires 25 are provided at the bottoms of the clean box 3, the support 11 and the external unit 50, respectively. Thereby, in the inspection apparatus 1, the clean unit 2, the apparatus main body 10, and the external unit 50 can be easily moved. When the inspection apparatus 1 is fixed, as shown in FIGS. 1 and 2, the support legs 6, 12, 51 are put on the floor and the tire 25 is left floating.
[0058]
Next, the inspection apparatus 1 will be described in more detail with reference to the block diagram of FIG.
[0059]
As shown in FIG. 4, the external unit 50 of the inspection apparatus 1 has an image processing computer 60 to which a display device 52 and an input device 54a are connected, and a control computer 61 to which a display device 53 and an input device 54b are connected. And are arranged. In FIG. 1 described above, the input device 54 a connected to the image processing computer 60 and the input device 54 b connected to the control computer 61 are collectively shown as the input device 54.
[0060]
The image processing computer 60 is a computer that captures and processes an image of a semiconductor wafer taken by CCD (charge-coupled device) cameras 30 and 31 installed inside the optical unit 21 when inspecting the semiconductor wafer. . That is, the inspection apparatus 1 inspects a semiconductor wafer by processing and analyzing an image of the semiconductor wafer taken by the CCD cameras 30 and 31 installed inside the optical unit 21 by the image processing computer 60. Do.
[0061]
The input device 54a connected to the image processing computer 60 is for inputting instructions necessary for analyzing the images taken from the CCD cameras 30 and 31 to the image processing computer 60. For example, it consists of a pointing device such as a mouse, a keyboard, and the like. The display device 52 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.
[0062]
The control computer 61 is a computer for controlling 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 like when inspecting a semiconductor wafer. That is, the inspection apparatus 1 controls the control computer so that when the semiconductor wafer is inspected, an image of the semiconductor wafer to be inspected is taken by the CCD cameras 30 and 31 installed in the optical unit 21. 61 controls the inspection stage 14, the elevator 22, the transfer robot 23 and the pre-aligner 24, and the devices inside the optical unit 21.
[0063]
Further, the control computer 61 has a function of controlling the blowers 5 a and 5 b of the clean air unit 4. That is, the inspection device 1 always supplies clean air into the clean box 3 when the semiconductor computer is inspected by controlling the blowers 5a and 5b of the clean air unit 4 by the control computer 61. Further, the airflow in the clean box 3 can be controlled.
[0064]
The input device 54b connected to the control computer 61 includes the inspection stage 14, the elevator 22, the transfer robot 23 and the pre-aligner 24, the devices inside the optical unit 21, and the blowers 5a and 5b of the clean air unit 4. Are input to the control computer 61, and include, for example, a pointing device such as a mouse, a keyboard, and the like. The display device 53 connected to the control computer 61 is for displaying various conditions at the time of inspecting the semiconductor wafer, and is composed of, for example, a CRT display or a liquid crystal display.
[0065]
The image processing computer 60 and the control computer 61 can exchange data with each other by a memory link mechanism. In other words, the image processing computer 60 and the control computer 61 are connected to each other via the memory link interfaces 60a and 61a provided in each, and the image processing computer 60 and the control computer 61 are mutually connected. Data exchange is possible.
[0066]
On the other hand, inside the clean box 3 of the inspection apparatus 1, as a mechanism for taking out the semiconductor wafer that has been carried in a sealed container 7 from the cassette 7b of the container 7 and placing it on the inspection stage 14, As described above, the elevator 22, the transfer robot 23, and the pre-aligner 24 are arranged. These are connected to a control computer 61 arranged in the external unit 50 via a robot control interface 61b. A control signal is sent from the control computer 61 to the elevator 22, the transport robot 23, and the pre-aligner 24 via the robot control interface 61b.
[0067]
That is, when the semiconductor wafer that has been carried in the sealed container 7 is taken out from the cassette 7b of the container 7 and placed on the inspection stage 14, the control computer 61 through the robot control interface 61b. Control signals are sent to the elevator 22, the transport robot 23, and the pre-aligner 24. Then, the elevator 22, the transfer robot 23, and the pre-aligner 24 operate based on this control signal. As described above, the semiconductor wafer that has been transferred into the sealed container 7 is transferred to the cassette 7b of the container 7. Take out from the pre-aligner 24 Phase out and center out are performed and placed on the inspection stage 14.
[0068]
In addition, a vibration isolation table 13 is disposed inside the clean box 3 of the inspection apparatus 1, and the X stage 15, the Y stage 16, the θ stage 17, and the Z stage are arranged on the vibration isolation table 13 as described above. An inspection stage 14 provided with 18 and a suction plate 19 is installed.
[0069]
Here, the X stage 15, the Y stage 16, the θ stage 17, the Z stage 18, and the suction plate 19 are connected to a control computer 61 disposed in the external unit 50 via a stage control interface 61c. A control signal is sent from the control computer 61 to the X stage 15, Y stage 16, θ stage 17, Z stage 18 and suction plate 19 via the stage control interface 61c.
[0070]
That is, when a semiconductor wafer is inspected, 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. . The X stage 15, Y stage 16, θ stage 17, Z stage 18, and suction plate 19 operate based on this control signal, and the suction plate 19 sucks and fixes the semiconductor wafer to be inspected. The stage 15, the Y stage 16, the θ stage 17, and the Z stage 18 move the semiconductor wafer to a predetermined position, angle, and height.
[0071]
Also, the vibration isolation table 13 On the top, as described above, the optical unit 21 is also installed. This optical unit 21 is for capturing an image of a semiconductor wafer at the time of inspection of a semiconductor wafer. As described above, the function of capturing an image of a semiconductor wafer to be inspected with low resolution using visible light. And a function of taking an image of a semiconductor wafer to be inspected with high resolution using ultraviolet light.
[0072]
The optical unit 21 has a visible light CCD camera 30, a halogen lamp 32, a visible light optical system 33, and a visible light objective lens 34 as a mechanism for capturing an image of a semiconductor wafer with visible light. And an autofocus control unit 35 for visible light.
[0073]
When an image of the semiconductor wafer is picked up with visible light, the halogen lamp 32 is turned on. Here, the drive source of the halogen lamp 32 is connected to a control computer 61 disposed 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 halogen lamp 32 via the light source control interface 61d. The halogen lamp 32 is turned on / off based on this control signal.
[0074]
When an image of the semiconductor wafer is picked up with visible light, the halogen lamp 32 is turned on, and the visible light from the halogen lamp 32 is transmitted through the visible light optical system 33 and the visible light objective lens 34 to the semiconductor. The semiconductor wafer is illuminated against the wafer. Then, the image of the semiconductor wafer illuminated with visible light is magnified by the visible light objective lens 34, and the magnified image is captured by the visible light CCD camera 30.
[0075]
Here, the visible light CCD camera 30 is connected to an image processing computer 60 disposed in the external unit 50 via an image capture interface 60b. The semiconductor wafer image captured by the visible light CCD camera 30 is captured by the image processing computer 60 via the image capture interface 60b.
[0076]
Further, when an image of a semiconductor wafer is picked up with visible light as described above, automatic focus position alignment is performed by the visible light autofocus control unit 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. Moves the visible light objective lens 34 or the Z stage 18 so that the inspection target surface of the semiconductor wafer coincides with the focal plane of the visible light objective lens 34.
[0077]
Here, the visible light autofocus control unit 35 is connected to a control computer 61 disposed in the external unit 50 via an autofocus control interface 61e. A control signal is sent from the control computer 61 to the visible light autofocus control unit 35 via the autofocus control interface 61e. The automatic focus position adjustment of the visible light objective lens 34 by the visible light autofocus control unit 35 is performed based on this control signal.
[0078]
The optical unit 21 has a CCD camera 31 for ultraviolet light, an ultraviolet light laser light source 36, an optical system 37 for ultraviolet light, and an objective for ultraviolet light as a mechanism for taking an image of a semiconductor wafer with ultraviolet light. A lens 38 and an ultraviolet autofocus control unit 39 are provided.
[0079]
Then, when an image of the semiconductor wafer is taken with ultraviolet light, the ultraviolet light source 36 is turned on. Here, the drive source of the ultraviolet laser light source 36 is connected to a control computer 61 disposed 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. The ultraviolet laser light source 36 is turned on / off based on this control signal.
[0080]
In addition, it is preferable to use the ultraviolet laser light source 36 that emits an ultraviolet laser having a wavelength of about 266 nm. An ultraviolet laser having a wavelength of about 266 nm is obtained as a fourth harmonic of a YAG laser. Laser light sources with an oscillation wavelength of about 166 nm have been developed. laser A light source may be used as the ultraviolet laser light source 36.
[0081]
When an image of a semiconductor wafer is taken with ultraviolet light, the ultraviolet laser light source 36 is turned on, and the ultraviolet light from the ultraviolet light laser light source 36 is passed through the ultraviolet light optical system 37 and the ultraviolet light objective lens 38. The semiconductor wafer is then illuminated and illuminated. Then, the image of the semiconductor wafer illuminated by the ultraviolet light is magnified by the ultraviolet light objective lens 38, and the magnified image is picked up by the ultraviolet light CCD camera 31.
[0082]
Here, the ultraviolet CCD camera 31 is connected to an image processing computer 60 disposed in the external unit 50 via an image capturing interface 60c. Then, the image of the semiconductor wafer captured by the ultraviolet CCD camera 31 is captured by the image processing computer 60 via the image capture interface 60c.
[0083]
Further, as described above, when an image of a semiconductor wafer is picked up with ultraviolet light, automatic focusing is performed by the ultraviolet light autofocus control unit 39. That is, the ultraviolet light autofocus control unit 39 detects whether or not the distance between the ultraviolet light objective lens 38 and the semiconductor wafer matches the focal length of the ultraviolet light objective lens 38. Moves the ultraviolet light objective lens 38 or the Z stage 18 so that the inspection target surface of the semiconductor wafer coincides with the focal plane of the ultraviolet light objective lens 38.
[0084]
Here, the ultraviolet autofocus control unit 39 is connected to a control computer 61 disposed in the external unit 50 via an autofocus control interface 61e. A control signal is sent from the control computer 61 to the ultraviolet light autofocus control unit 39 via the autofocus control interface 61e. The automatic focusing position adjustment of the ultraviolet light objective lens 38 by the ultraviolet light autofocus control unit 39 is performed based on this control signal.
[0085]
Further, the clean air unit 4 is provided with two blowers 5a and 5b as described above. These blowers 5a and 5b are connected to a control computer 61 disposed in the external unit 50 through 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 rotational speed of the blowers 5a and 5b, switching between on / off, and the like are performed based on this control signal.
[0086]
Next, the optical system of the optical unit 21 of the inspection apparatus 1 will be described in more detail with reference to FIG. Here, description of the autofocus control units 35 and 39 is 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.
[0087]
As shown in FIG. 5, the optical unit 21 includes a halogen lamp 32, a visible light optical system 33, and a visible light objective lens 34 as an optical system for capturing an image of a semiconductor wafer with visible light. I have.
[0088]
Visible light from the halogen lamp 32 is guided to the visible light optical system 33 by the optical fiber 40. 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. The visible light incident on the half mirror 43 is reflected by the half mirror 43 toward the visible light objective lens 34 and enters the semiconductor wafer via the visible light objective lens 34. Thereby, the semiconductor wafer is illuminated with visible light.
[0089]
The image of the semiconductor wafer illuminated with visible light is enlarged by the visible light objective lens 34, 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 is incident on the visible light CCD camera 30 via the visible light objective lens 34, the half mirror 43, and the imaging lens 44. An enlarged image is captured by the visible light CCD camera 30. Then, an image of the semiconductor wafer (hereinafter referred to as a visible image) picked up by the visible light CCD camera 30 is sent to the image processing computer 60.
[0090]
The optical unit 21 includes an ultraviolet laser light source 36, an ultraviolet light optical system 37, and an ultraviolet light objective lens 38 as an optical system for capturing an image of a semiconductor wafer with ultraviolet light. .
[0091]
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. The visible light incident on the half mirror 48 is reflected by the half mirror 48 toward the ultraviolet light objective lens 38 and enters the semiconductor wafer via the ultraviolet light objective lens 38. Thereby, the semiconductor wafer is illuminated with ultraviolet light.
[0092]
The image of the semiconductor wafer illuminated with ultraviolet light is magnified by the ultraviolet light objective lens 38, 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 the ultraviolet light is incident on the ultraviolet CCD camera 31 through the ultraviolet objective lens 38, the half mirror 48, and the imaging lens 49. An enlarged image is picked up by the CCD camera 31 for ultraviolet light. An image of the semiconductor wafer (hereinafter referred to as an ultraviolet image) captured by the ultraviolet CCD camera 31 is sent to the image processing computer 60.
[0093]
In the inspection apparatus 1 as described above, an image of a semiconductor wafer can be captured and inspected with ultraviolet light, which is light having a wavelength shorter than that of visible light. Therefore, detection and classification of defects are performed using visible light. Compared with the case where it carries out, a finer defect detection and classification can be performed.
[0094]
In addition, the inspection apparatus 1 has both an optical system for visible light and an optical system for ultraviolet light, so that inspection of a semiconductor wafer with low resolution using visible light and high resolution using ultraviolet light are possible. Both of the semiconductor wafer inspection and the semiconductor wafer inspection can be performed. Therefore, in the inspection apparatus 1, large defects are detected and classified by inspection of the semiconductor wafer at low resolution using visible light, and inspection of the semiconductor wafer at high resolution using ultraviolet light is performed. It is also possible to detect and classify small defects.
[0095]
In the inspection apparatus 1, the objective lens for ultraviolet light 38 The numerical aperture NA is preferably larger, for example 0.9 or more. Thus, the objective lens for ultraviolet light 38 As a result, a finer defect can be detected by using a lens having a large numerical aperture NA.
[0096]
By the way, when the defect of the semiconductor wafer is composed only of irregularities without color information like a scratch, the defect can hardly be seen with light having no coherence. On the other hand, when light with excellent coherence such as laser light is used, even if the defect has no color information and has only irregularities, such as scratches, light is emitted near the irregularities. By interfering, the defect can be clearly seen. The inspection apparatus 1 uses an ultraviolet laser light source 36 that emits ultraviolet laser light as an ultraviolet light source. Therefore, the inspection apparatus 1 can clearly detect the defect even if the defect has no color information and has only unevenness, such as a scratch. That is, in the inspection apparatus 1, phase information that is difficult to detect with visible light (incoherent light) from the halogen lamp 32 is easily detected using the ultraviolet light laser (coherent light) from the ultraviolet light source 36. can do.
[0097]
Next, an example of a procedure when the semiconductor wafer is inspected by the inspection apparatus 1 will be described with reference to the flowchart of FIG. In the flowchart of FIG. 6, the processing procedure after the state in which the semiconductor wafer to be inspected is placed on the inspection stage 14 is shown. Further, the flowchart shown in FIG. 6 shows an example of a procedure for performing classification by inspecting the defect by the inspection apparatus 1 when the position of the defect on the semiconductor wafer is known in advance. Also, here, it is assumed that many similar device patterns are formed on a semiconductor wafer, and defect detection and classification are performed by using an image of a defect area (defect image) and an image of other areas (reference image). ), And comparing them.
[0098]
First, as shown in step S1-1, the defect position coordinate file is read into the control computer 61. Here, the defect position coordinate file is a file in which information on 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. Here, the defect position coordinate file is read into the control computer 61.
[0099]
Next, in step S1-2, the X stage 15 and the Y stage 16 are driven by the control computer 61, the semiconductor wafer is moved to the defect position coordinates indicated by the defect position coordinate file, and the inspection target area of the semiconductor wafer is visible light. The objective lens 34 is within the field of view.
[0100]
Next, in step S <b> 1-3, the visible light autofocus control unit 35 is driven by the control computer 61 to perform automatic focus alignment of the visible light objective lens 34.
[0101]
Next, in step S <b> 1-4, 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. Note that 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 an area where there is a defect (hereinafter referred to as a defect image).
[0102]
Next, in step S1-5, the X stage 15 and the Y stage 16 are driven by the control computer 61, the semiconductor wafer is moved to the reference position coordinates, and the reference area of the semiconductor wafer is the visual field of the visible light objective lens 34. Get inside. 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.
[0103]
Next, in step S1-6, the control computer 61 drives the visible light autofocus control unit 35 to perform automatic focus alignment of the visible light objective lens.
[0104]
Next, in step S1-7, an image of the semiconductor wafer is picked up by the visible light CCD camera 30, and the picked-up visible image is sent to the image processing computer 60. The visible image captured here is an image of an area where a device pattern similar to the device pattern in the inspection target area of the semiconductor wafer is formed (hereinafter referred to as a reference image).
[0105]
Next, in step S1-8, the image processing computer 60 compares the defect image captured in step S1-4 with the reference image captured in step S1-7, and detects a defect from the defect image. If a defect can be detected, the process proceeds to step S1-9. If a defect cannot be detected, the process proceeds to step S1-11.
[0106]
In step S1-9, the image processing computer 60 examines what the detected defect is and classifies it. If the defect classification is completed, the process proceeds to step S1-10. If the defect classification cannot be performed, the process proceeds to step S1-11.
[0107]
In step S1-10, the defect classification result 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. The defect classification result may be transferred to and stored in another computer connected to the image processing computer 60 or the control computer 61 via a network.
[0108]
When the process in step S1-10 is completed, the classification of defects of the semiconductor wafer is completed, and thus the process ends. 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.
[0109]
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 thereafter, and high resolution is obtained using ultraviolet light. Defect detection and classification are performed by imaging.
[0110]
In that case, first, in step S1-11, the X stage 15 and the Y stage 16 are driven by the control computer 61, and the semiconductor wafer is moved to the defect position coordinates indicated by the defect position coordinate file. The region is set within the field of view of the objective lens 38 for ultraviolet light.
[0111]
Next, in step S1-12, the control computer 61 drives the ultraviolet light autofocus control unit 39 to perform automatic focus alignment of the ultraviolet light objective lens 38.
[0112]
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, the imaging of the defect image here is performed with higher resolution than that in the case of using visible light by using ultraviolet light, which is light having a shorter wavelength than visible light.
[0113]
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, so that the reference region of the semiconductor wafer is the field of view of the ultraviolet objective lens 38. Get inside. 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.
[0114]
In step S1-15, the control computer 61 drives the ultraviolet light autofocus control unit 39 to perform automatic focus alignment of the ultraviolet light objective lens 38.
[0115]
In step S1-16, an image of the semiconductor wafer is picked up by the ultraviolet CCD camera 31, and the picked-up 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. Further, the reference image is captured here using ultraviolet light having a shorter wavelength than visible light with higher resolution than when visible light is used.
[0116]
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. If a defect can be detected, the process proceeds to step S1-18. If a defect cannot be detected, the process proceeds to step S1-19.
[0117]
In step S1-18, the image processing computer 60 examines what the detected defect is and classifies it. If the defect classification is 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.
[0118]
In step S1-19, information indicating that the defect cannot be classified is stored. Here, the information indicating that the defect classification could not be performed is stored in, for example, a storage device connected to the image processing computer 60 or the control computer 61. This information may be transferred to and stored in another computer connected to the image processing computer 60 or the control computer 61 via a network.
[0119]
According to the above procedure, first, a semiconductor wafer is inspected at a low resolution by processing and analyzing an image captured by the visible light CCD camera 30 to detect and classify defects with visible light. If not, next, the semiconductor wafer is inspected with high resolution by processing and analyzing the image captured by the ultraviolet CCD camera 31.
[0120]
Here, a method for detecting a defect from a reference image and a defect image captured by the CCD cameras 30 and 31 will be described with reference to FIG.
[0121]
FIG. 7A shows an example of an image of a reference area on which a device pattern similar to the device pattern in the inspection target area is formed, that is, a reference image. FIG. 7B shows an example of an image of a region to be inspected that has a defect, that is, a defect image.
[0122]
When a defect is detected from such a reference image and a defect image, a device pattern is extracted from the reference image based on color information and shading information as shown in FIG. 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.
[0123]
Then, as shown in FIG. 7E, an image obtained by superimposing the device pattern extraction result image shown in FIG. 7C and the defect extraction result image shown in FIG. 7D is obtained. The ratio of the defect existing in the device pattern is extracted as a feature amount related to the defect.
[0124]
By the above-described method, the reference image and the defect image captured by the CCD cameras 30 and 31 are processed and analyzed by the image processing computer 60, so that the defect can be detected and the semiconductor wafer can be inspected.
[0125]
As described above, the inspection apparatus 1 first inspects a semiconductor wafer with low resolution by processing and analyzing an image captured by the visible light CCD camera 30 to detect defects in visible light. When the classification cannot be performed, the semiconductor wafer is inspected at high resolution by processing and analyzing the image captured by the ultraviolet CCD camera 31. Compared with the case of detecting and classifying defects using the, it is possible to detect and classify finer defects.
[0126]
However, since the area that can be imaged at once is wider when imaging with low resolution using visible light, if the defect is sufficiently large, the semiconductor wafer was inspected with low resolution using visible light. Is more efficient. Therefore, rather than using ultraviolet light from the beginning to inspect and classify defects, as described above, by first inspecting and classifying defects using visible light, it is more efficient. A semiconductor wafer can be inspected.
[0127]
By the way, in this inspection apparatus 1, as described above, the X-stage 15 and the Y-stage 16 that move in directions orthogonal to each other move the semiconductor wafer that is the inspection object in the horizontal direction, and the device pattern to be inspected It leads to a predetermined inspection position.
[0128]
Here, FIG. 8 is a plan view schematically showing the X stage 15 and the Y stage 16 from above the apparatus main body 10.
[0129]
As shown in FIG. 8, the X stage 15 and the Y stage 16 are provided with an X stage moving means and a Y stage moving means for moving the X stage 15 and the Y stage 16 in directions orthogonal to each other. The semiconductor wafer 70 is moved to a predetermined position.
[0130]
Specifically, as shown in FIGS. 8 and 9, the X stage 15 is a pair of first rail mechanisms 71 and 72 disposed on the stone surface plate 13 a of the vibration isolation table 13 as X stage moving means. And a first drive mechanism 73 arranged in parallel between the pair of first rail mechanisms 71, 72. FIG. 9 is a side view of the main part of the apparatus main body 10 as seen schematically from the direction of arrow A1 in FIG.
[0131]
As shown in FIG. 9, the pair of first rail mechanisms 71 and 72 is for sliding in the direction of arrow C in FIG. 8 while supporting the X stage 15, and is supported on the stone surface plate 13a. Further, the first rail portions 71a and 72a and the first slider portions 71b and 72b fixed to the X stage 15 side slide while engaging with each other.
[0132]
On the other hand, the first drive mechanism 73 is for driving the X stage 15 supported by the first rail mechanisms 71 and 72, and is positioned below the X stage 15. A first ball screw 74 attached to the lower surface, and a first drive shaft 76 screwed into the first ball screw 74 and rotatably supported by a pair of first bearing portions 75a and 75b. The first drive shaft 76 is provided with a first servo motor 78 connected to one end of the first drive shaft 76 via a first coupling 77.
[0133]
The first ball screw 74 is attached to the lower surface of the X stage 15 so as to be positioned at both ends in the direction of arrow C in FIG. The first ball screw 74 is screwed to the first drive shaft 76 via a ball. When the first drive shaft 76 is rotationally driven, the shaft of the first drive shaft 76 is rotated. It is set as the structure which moves along a direction (arrow C direction in FIG. 8).
[0134]
On the other hand, both ends of the first drive shaft 76 are rotatably supported by the pair of first bearing portions 75a and 75b, and the first drive shaft 76 is interposed between the pair of first bearing portions 75a and 75b. The ball screw 74 is configured to move while being screwed. The pair of first bearing portions 75a and 75b includes, for example, the first bearing portion 75a provided on one end side as an angular bearing and the first bearing portion 75b provided on the other end side. Radial bearings are used.
[0135]
The first servo motor 78 drives the first drive shaft 76 to rotate, and is connected to the end of the first drive shaft 76 on the first bearing portion 75 a side via the first coupling 77. ing. The first servo motor 78 is connected to the stage control interface 61c described above, and operates based on a control signal from the stage control interface 61c.
[0136]
In the first drive mechanism 73, when the first servo motor 78 rotates and drives the first drive shaft 76, the first ball screw 74 moves in the axial direction of the first drive shaft 76 (arrow C in FIG. 8). Direction). Then, the X stage 15 attached to the first ball screw 74 is horizontally moved in the direction of arrow C in FIG. 8 while being supported by the first rail mechanisms 71 and 72.
[0137]
Similarly, as shown in FIGS. 8 and 10, the Y stage 16 includes a pair of second rail mechanisms 79 and 80 disposed on the X stage 15 as a Y stage moving unit, and a pair of second rails. And a second drive mechanism 81 arranged in parallel between the rail mechanisms 79 and 80. FIG. 10 is a side view of the main part of the apparatus main body 10 viewed from the direction of arrow A2 in FIG.
[0138]
As shown in FIG. 10, the pair of second rail mechanisms 79 and 80 are for sliding in the direction of arrow D in FIG. 8 while supporting the Y stage 16, and are supported on the X stage 15. The second rail portions 79a and 80a and the second slider portions 79b and 80b fixed on the Y stage 16 side slide while engaging with each other.
[0139]
On the other hand, the second drive mechanism 81 is for driving the Y stage 16 supported by the second rail mechanisms 79 and 80, and is positioned below the Y stage 16. A second ball screw 82 attached to the lower surface, and a second drive shaft 84 screwed to the first ball screw 82 and rotatably supported by a pair of second bearing portions 83a and 83b. The second drive shaft 84 is provided with a second servo motor 86 connected to one end of the second drive shaft 84 via a second coupling 85.
[0140]
The second ball screw 82 is attached to the lower surface of the Y stage 16 so as to be positioned at both ends in the direction of arrow D in FIG. The second ball screw 82 is screwed to the second drive shaft 82 via a ball. When the second drive shaft 84 is driven to rotate, the axial direction of the drive shaft 84 (see FIG. 8 in the direction of arrow D).
[0141]
On the other hand, both ends of the second drive shaft 84 are rotatably supported by a pair of second bearing portions 83a and 83b, and the second drive shaft 84 is interposed between the pair of second bearing portions 83a and 83b. The ball screw 82 is configured to move while being screwed. The pair of second bearing portions 83a and 83b includes, for example, the second bearing portion 83a provided on one end side as an angular bearing and the second bearing portion 83b provided on the other end side. Radial bearings are used.
[0142]
The second servo motor 86 rotates the second drive shaft 84, and is coupled to the end of the second drive shaft 84 on the second bearing portion 83 a side via a coupling 85. The second servo motor 86 is connected to the stage control interface 61c described above, and operates based on a control signal from the stage control interface 61c.
[0143]
In the second drive mechanism 81, when the second servomotor 86 rotates the second drive shaft 84, the second ball screw 82 moves in the axial direction of the second drive shaft 84 (arrow D in FIG. 8). Direction). Then, the Y stage 16 attached to the second ball screw 82 moves horizontally in the direction of arrow D in FIG. 8 while being supported by the second rail mechanisms 79 and 80.
[0144]
Here, as described above, the X stage 15 and the Y stage 16 are connected to the control computer 61 disposed in the external unit 50 via the stage control interface 61c. A control signal is sent from the control computer 61 to the X stage 15 and the Y stage 16 via the stage control interface 61c. Then, the X stage 15 and the Y stage 16 guide the semiconductor wafer to a predetermined inspection position based on this control signal.
[0145]
Specifically, the first rail mechanism is driven by driving the first drive mechanism 73 of the X stage 15 and the second drive mechanism 81 of the Y stage 16 based on a control signal from the stage control interface 61c. The X stage 15 and the Y stage 16 supported by 71 and 72 and the second rail mechanisms 79 and 80 are moved to predetermined positions.
[0146]
By the way, in the X stage 15 and the Y stage 16, in order to guide the semiconductor wafer 70 to a predetermined inspection position, the X stage 15 and the Y stage 16 are detected and the X stage 15 and the Y stage 16 are detected based on the detected signals. So-called positioning servo is performed to move the stage 15 and the Y stage 16 to predetermined positions.
[0147]
However, in the conventional inspection apparatus, when such positioning servo is performed, the X stage 15 and the Y stage 16 cannot be accurately positioned at predetermined positions, resulting in a significant decrease in inspection capability. There was a thing.
[0148]
Therefore, in this inspection apparatus 1, sliding resistance is added to the first drive shaft 76 of the X stage 15 and the second drive shaft 84 of the Y stage 16, and the first drive mechanism 73 and the second drive shaft 84 are added. By adjusting the sliding resistance applied to the drive shaft 84, the X stage 15 and the Y stage 16 are accurately positioned at predetermined positions.
[0149]
More specifically, as shown in FIGS. 8 to 10, the inspection apparatus 1 is slid with respect to the first drive shaft 76 at the end on the first bearing portion 75 b side of the first drive shaft 76. A first sliding contact resistance adding means 87 for adding contact resistance in an adjustable manner; Bearing part A second sliding contact resistance adding means 88 is provided at the 83b side end to adjust the sliding contact resistance to the second drive shaft 84 in an adjustable manner.
[0150]
In the following description, the first sliding contact resistance adding unit 87 and the second sliding contact resistance adding unit 88 have the same configuration, and thus the first sliding contact resistance adding unit 87 and the second sliding contact adding unit 88 have the same configuration. The contact resistance adding means 88 will be described as the sliding contact resistance adding means 90, and the first drive shaft 76 and the second drive shaft 84 will be described as the drive shaft 91.
[0151]
As shown in FIG. 11, the sliding contact resistance adding means 90 adjusts the sliding contact member 92 that is in sliding contact with the outer peripheral surface of the drive shaft 91 and the contact pressure of the sliding contact member 92 with respect to the outer peripheral surface of the drive shaft 91. A mechanism 93 and a support member 94 that supports the sliding contact member 92 are provided.
[0152]
The slidable contact member 92 includes a slidable contact surface portion 95 that is in slidable contact with the outer peripheral surface of the drive shaft 91, an opening 96 provided by cutting out a part of the slidable contact surface portion 95, and the slidable contact portion. It consists of an elastic member which has several groove part 97a, 97b which divides the perimeter of the surface part 95 by predetermined spacing. As the material of the sliding contact member 92, a material having elasticity, low wear, less generation of swarf, and stable friction resistance is preferable. Examples thereof include MC nylon and POM. be able to.
[0153]
As shown in FIG. 12, the sliding contact surface portion 95 is a surface in sliding contact with the drive shaft 91 that passes through the sliding contact member 92, and a part of the peripheral surface of the hole 98 that passes through the sliding contact member 92 is the drive shaft 91. Projected to the side.
[0154]
As shown in FIG. 11, the opening 96 is formed by cutting out with a predetermined width from the upper surface of the sliding contact member 92 to the sliding contact surface portion 95.
[0155]
The plurality of groove portions 97 a and 97 b are configured so that the slidable contact surface portion 95 is divided at a predetermined interval so that the divided slidable contact surface portion 95 contacts the outer peripheral surface of the drive shaft 91 uniformly.
[0156]
As shown in FIGS. 11 and 12, the adjustment mechanism 93 is configured such that the upper part divided by the opening 96 of the sliding contact member 92 is fastened by the fastening bolt 100 from both sides via springs 99.
[0157]
In this adjustment mechanism 93, the spring 99 presses the sliding contact member 92. By adjusting the tightening of the adjustment nut 100a of the fastening bolt 100, the pressing of the spring 99 against the sliding contact member 92 is changed, The width of the opening 96 of the sliding contact member 92 can be changed. In the sliding contact member 92, the contact pressure of the sliding contact surface portion 95 with respect to the outer peripheral surface of the drive shaft 91 can be changed by changing the width of the opening 96. Therefore, in this sliding contact resistance adding means 90, the contact mechanism with respect to the outer peripheral surface of the drive shaft 91 of the sliding contact member 92 can be adjusted by the adjusting mechanism 93.
[0158]
The support member 94 is formed of a long member, and a sliding contact member 92 is attached to the substantially central portion thereof with a screw 101. The supporting member 94 is fixed to the stone surface plate 13 a or the X stage 15 with bolts 102 while supporting the sliding member 92.
[0159]
The sliding contact resistance adding means 90 configured as described above is in sliding contact with the outer peripheral surface of the drive shaft 91 that is rotationally driven when the X stage 15 and the Y stage 16 are moved to predetermined positions. The sliding contact surface portion 95 of the member 92 adds sliding resistance while sliding.
[0160]
Thereby, in the inspection apparatus 1, the X stage 15 and the Y stage 16 can be accurately positioned at predetermined positions.
[0161]
Here, the positioning servo between the inspection apparatus 1 provided with the sliding contact resistance adding means 90 and the inspection apparatus not provided with the sliding contact resistance adding means 90 as in the prior art was measured. Hereinafter, the measurement results are shown in FIGS. In FIGS. 13 and 14, the horizontal axis indicates the elapsed time, and the vertical axis indicates the amount of movement of the inspection stage 14.
[0162]
As shown in FIG. 13, in the conventional inspection apparatus, it can be seen that the inspection stage 14 is slightly vibrated, and the inspection stage 14 is not accurately positioned. On the other hand, in this inspection apparatus 1, as shown in FIG. 14, it can be seen that the inspection stage 14 is not moved and the inspection stage 14 is accurately positioned. As described above, in the inspection apparatus 1, the inspection stage 14 on which the semiconductor wafer 70 to be inspected is placed can be accurately positioned at a predetermined position.
[0163]
Further, the sliding contact resistance adding means 90 can arbitrarily adjust the contact pressure with respect to the outer peripheral surface of the drive shaft 91 of the sliding contact member 92 by the adjusting mechanism 93, and adjust the sliding contact resistance applied to the drive shaft 91. It can be done easily.
[0164]
Therefore, in this inspection apparatus 1, when the X stage 15 and the Y stage 16 are moved to predetermined positions, the sliding contact member 92 adds a sliding contact resistance to the rotationally driven drive shaft 91. By adjusting the sliding resistance applied to the drive shaft 91 by the adjusting mechanism 93, the inspection stage 14 on which the semiconductor wafer 70 is placed can be accurately positioned at a predetermined position, and the inspection capability is greatly improved. Can be achieved.
[0165]
In particular, since this inspection apparatus 1 inspects the semiconductor wafer 70 with high resolution using ultraviolet light, such sliding contact resistance adding means 90 is provided as a drive shaft. 91 It is very effective when the inspection stage 14 is accurately positioned.
[0166]
Moreover, in the said inspection apparatus 1, as shown in FIG. 15, it is good also as a structure by which the radiation fin 103 was provided as a thermal radiation means for radiating the frictional heat which the sliding contact resistance addition means 90 dissipated. The radiating fin 103 has a drive shaft at a position where the sliding contact member 92 is sandwiched. 91 It is provided so as to cover the outer peripheral surface of. As a result, the sliding contact member 92 has a sliding contact surface portion 95 with a drive shaft. 91 It is possible to efficiently dissipate the frictional heat generated by the sliding contact, and to prevent the sliding contact resistance of the sliding contact surface portion 95 from being greatly changed by the frictional heat. Therefore, in this inspection apparatus 1, the drive shaft 91 Therefore, a stable sliding contact resistance can be added.
[0167]
Further, in the sliding contact resistance adding means 90, the adjusting mechanism 93 is not necessarily limited to the above-described configuration. For example, an air cylinder is provided instead of the spring 99, and the opening portion of the sliding contact member 92 is formed by air pressure. It is good also as a structure which changes the width | variety of 96 and adjusts the contact pressure with respect to the outer peripheral surface of the drive shaft 91 of this sliding contact member 92. FIG.
[0168]
Further, the sliding contact resistance adding means 90 may be configured such that an actuator is provided in the adjusting mechanism 93 to control the adjustment of the contact pressure with respect to the outer peripheral surface of the drive shaft 91 of the sliding contact member 92. Thereby, when the drive shaft 91 is driven, no sliding contact resistance is added to the drive shaft 91 until the positioning servo is performed, or when the drive shaft 91 is stopped, the sliding contact resistance is strengthened against the drive shaft 91. It is possible to perform a switching operation such as adding to the.
[0169]
In the above description, the inspection apparatus 1 to which the present invention is applied has been used for examining what a defect of a semiconductor wafer is. However, the application of the inspection apparatus 1 according to the present invention can be used for applications other than defect identification of semiconductor wafers. That is, the inspection apparatus 1 according to the present invention can be used, for example, to inspect whether or not a device pattern formed on a semiconductor wafer is formed in an appropriate shape according to a desired pattern. Furthermore, the use of the inspection apparatus 1 according to the present invention is not limited to the inspection of semiconductor wafers, and the inspection apparatus 1 according to the present invention can be widely applied to inspection of fine patterns. It is also effective for inspection of flat panel displays on which various patterns are formed.
[0170]
【The invention's effect】
As described above in detail, in the inspection apparatus according to the present invention, a sliding resistance is added to the drive shaft of the stage, and the inspection object is loaded by adjusting the sliding resistance applied to the drive shaft. The placed stage can be accurately positioned at a predetermined inspection target position, and the inspection capability can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an appearance of an inspection apparatus to which the present invention is applied.
FIG. 2 is a view showing a state in which an apparatus main body disposed in a clean box of the inspection apparatus is viewed from the direction of an arrow A1 in FIG.
FIG. 3 is a plan view schematically showing an apparatus main body of the inspection apparatus.
FIG. 4 is a block diagram illustrating a configuration example of the inspection apparatus.
FIG. 5 is a diagram illustrating a configuration example of an optical system of an optical unit of the inspection apparatus.
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 technique for detecting a defect from a reference image and a defect image.
FIG. 8 is a plan view schematically showing the X stage and the Y stage of the inspection apparatus as viewed from the upper side of the apparatus main body.
FIG. 9 is a side view of the main part of the apparatus main body of the inspection apparatus as viewed typically from the direction of arrow A1 in FIG.
10 is a side view of an essential part of the apparatus main body of the inspection apparatus as viewed schematically from the direction of arrow A2 in FIG. 8. FIG.
FIG. 11 is a diagram showing a configuration of sliding contact resistance adding means.
FIG. 12 is a cross-sectional view showing a configuration of a sliding contact member.
FIG. 13 is a characteristic diagram showing a result of measurement of a positioning servo of the inspection apparatus.
FIG. 14 is a characteristic diagram showing a result of measurement of a positioning servo of a conventional inspection apparatus.
FIG. 15 is a plan view showing a configuration in which a radiating fin is provided in the sliding contact resistance adding means.
FIG. 16 is a diagram for explaining a positioning servo.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inspection apparatus, 2 Clean unit, 3 Clean box, 4 Clean air unit, 5a, 5b Blower, 10 Main body, 14 Inspection stage, 21 Optical unit, 22 Elevator, 23 Transport robot, 24 Pre-aligner, 30 For visible light CCD camera, 31 Ultraviolet light CCD camera, 32 Halogen lamp, 33 Visible light optical system, 34 Visible light objective lens, 36 Ultraviolet light source, 37 Ultraviolet light optical system, 38 Ultraviolet light objective lens, 50 External Unit, 52, 53 display device, 54 input device, 60 image processing computer, 61 control computer, 70 semiconductor wafer, 71, 72 first rail mechanism, 73 first drive mechanism, 74 first ball screw, 76 1st drive shaft, 78 1st servo motor, 79, 80 2nd rail mechanism, 8 DESCRIPTION OF SYMBOLS 1 2nd drive mechanism, 82 2nd ball screw, 84 2nd drive shaft, 86 2nd servomotor, 87 1st sliding contact resistance addition means, 88 2nd sliding contact resistance addition means, 90 slide Contact resistance adding means, 91 drive shaft, 92 sliding member, 93 adjusting mechanism, 94 support member, 95 sliding contact surface portion, 96 opening, 97a, 97b groove portion, 99 spring, 100 fastening bolt, 100a adjusting nut, 103 heat radiating fin

Claims (5)

A stage on which the object to be inspected is placed;
Stage moving means for moving to a predetermined inspection target position while controlling the stage on which the inspection object is placed;
Slidable resistance adding means for adjusting slidable resistance to the drive shaft of the stage moving means in an adjustable manner,
The slidable contact resistance adding means includes a slidable contact member slidably contacting the peripheral surface of the drive shaft, and a slidable contact resistance adjusting means for adjusting a contact pressure of the slidable contact member with respect to the peripheral surface of the drive shaft,
The slidable contact member includes a slidable contact surface portion that is slidably contacted with the peripheral surface of the drive shaft, an opening provided by cutting out a part of the slidable contact surface portion, and the entire slidable contact surface portion. It consists of MC nylon or POM having a plurality of grooves that divide the circumference at predetermined intervals,
The said sliding contact resistance adjustment means adjusts the contact pressure with respect to the surrounding surface of the said drive shaft by changing the width | variety of the opening part of the said sliding contact member, The inspection apparatus characterized by the above-mentioned. The sliding resistance adjusting means, inspection apparatus according to claim 1, characterized in that the width of the opening of the sliding member is changed by the spring pressure. Inspection apparatus according to claim 1, characterized in that it comprises a sliding resistance control means for controlling the sliding resistance adjusting means.   2. The inspection apparatus according to claim 1, further comprising a heat dissipating means for dissipating heat generated by the sliding contact resistance adding means.   The inspection apparatus according to claim 1, wherein the inspection object is inspected by irradiating the inspection object with ultraviolet light and detecting reflected light or transmitted light.

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