JP3218015B2 - Semiconductor wafer observation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer observation apparatus having a wafer transfer mechanism for measuring the shape, defects and foreign matters on the surface of a semiconductor wafer, defects inside the wafer, and the line width and electrical characteristics of a patterned wafer. .

[0002]

2. Description of the Related Art In recent years, semiconductor technology has advanced rapidly and the degree of integration has been dramatically improved. At the same time, improving the yield is a major issue in each semiconductor manufacturing process, and as one of the solutions, the size (diameter) of the semiconductor wafer has been increased. Recently, 300mm (1
Research and development of wafers (2 inches) have progressed, and mass production technology has been almost established.

[0003] Conventional wafers up to 200 mm (8 inches) in size are stored in dedicated cassettes for each size. The cassette in which the wafers are stored is mounted on various observation devices and inspection devices such as a scanning electron microscope and an optical particle inspection device, and is transported to a predetermined position by a wafer transport mechanism. At this time, the cassette is placed on a dedicated table corresponding to the wafer size. A commercially available wafer cassette is 100 mm depending on the size of each wafer.
(4 inches), 125 mm (5 inches), 150 mm
(6 inches) and 200 mm (8 inches) cassettes. Cassette fixed bases are classified into a dedicated type that supports only a specific cassette size and a common type that can support a plurality of cassette sizes. As shown in FIG. 7 (a), the dedicated type is provided with a convex or concave guide in contact with the front and rear walls of the cassette bottom to hold the cassette bottom, and regulates the movement to the left and right and the front and rear. Further, as shown in FIG. 7 (b), in the common type, a convex or concave step-like guide is provided in front and rear of the cassette in order to hold the cassette bottom similarly to the dedicated type, thereby restricting the left / right and front / back movement. ing. At this time, it is possible to cope with a plurality of cassette sizes by making the guide stepwise.

[0004] Cassettes for 300 mm wafers are available from Semiconductor Equipment and Materi, an international standardization organization for semiconductors.
als International (SEMI) and Japan 300mm Semiconductor Technology Association
Conference (J 300)
Physical Interface and Carrie SEAJ / SEMI Joint Sem
inar (1997.4.30) "summarizes international standards.
In this, the shape of the cassette and the arrangement and shape of the pins attached to the cassette fixing table for fixing the cassette are clearly shown. As shown in FIG. 8, the cassette corresponding to the 300 mm wafer is greatly different in shape and structure from the conventional cassette up to 200 mm. Therefore, 30
Cassettes for 0 mm wafers are available from SEMI and J3
As shown in the standard No. 00, three pins are set on the cassette fixing base and the cassette is placed on the three pins.

[0005]

As shown in the above prior art, the shape of the 300 mm cassette is greatly different from that of the conventional cassette up to 200 mm. Likewise 300
The shape of the mm cassette fixing table is also greatly different from the fixing table up to the 200 mm cassette, so that there is a problem that both cannot be shared by one fixing table. In addition, when a 300 mm wafer and a wafer up to 200 mm are arbitrarily transferred and observed, it is necessary to remove and replace the cassette fixing base. When the cassette fixing table is replaced, a teaching operation for setting a position for taking out the wafer from the cassette by the wafer transfer mechanism must be performed each time, and there is a problem that operability is poor. However, at the present stage of semiconductor R & D, 300 mm wafers and 2
There is a demand to arbitrarily observe a wafer of 00 mm or less.

Therefore, an object of the present invention is to solve the above-mentioned problems by as much as a 300 mm wafer.
An object of the present invention is to provide a semiconductor wafer observation apparatus having a cassette fixing base that can mount and fix each cassette, or can share both of them so that a wafer of 0 mm or less can be observed.

[0007]

Means for Solving the Problems In order to solve the above problems, the present invention is characterized in that the following means are taken. (1) A wafer storage container for storing a plurality of semiconductor wafers, a wafer storage container fixing table for fixing the wafer storage container at a predetermined position, a wafer size discriminating mechanism for detecting the size of the wafer, and a sample table for mounting the wafer. It has a wafer transfer mechanism for transferring a wafer to an arbitrary place, a transfer mechanism for moving the wafer transferred on the sample table to a desired position, and an observation means for observing the wafer, and a single or a plurality of wafer storage containers having different sizes. Of the wafer storage container fixed table.

(2) The wafer storage container fixing base is 30
The wafer storage containers of 0 mm, 200 mm, and 150 mm were shared by a single wafer storage container fixing stand. (3) On the upper surface of the 300 mm wafer storage container fixing table, a wafer storage container fixing table commonly used for the 200 mm and 150 mm wafer storage containers was placed.

(4) A single wafer storage container fixing table, either a 200 mm or 150 mm wafer storage container, is placed on the upper surface of the 300 mm wafer storage container fixing table. (5) The wafer storage container fixing table and the 300 mm wafer storage container fixing table have a storage container presence / absence detector and a storage container size detector.

[0010]

In the semiconductor wafer observation apparatus configured as described above, a 300 mm wafer-compatible cassette and a 200 m
By sharing a cassette of m or less, a cassette for a wafer of a desired size can be placed and fixed at a predetermined position without exchanging a cassette fixing base. By storing in advance the positions of the wafers in the determined cassette, the wafers are sent from the cassette to the wafer size discriminating mechanism in accordance with the sequence determined by the transport mechanism, and the wafer size is automatically adjusted. After being detected and aligned in a predetermined direction at the same time, the wafer is transported to the upper surface of the sample stage on the moving mechanism, and is moved to the observation position of the wafer observing means by the moving mechanism. Further, since the cassette presence detector is provided, it is possible to prevent the transport device from being damaged due to malfunction. Furthermore, since the cassette size detector is provided, the cassette size is automatically identified, the transport mechanism operates at a predetermined position according to each cassette size, and the wafers in the cassette are subjected to wafer size discrimination. The wafer is transported onto the mechanism and the wafer moving mechanism, and operates to return to the cassette again after the wafer is observed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
It will be described based on. FIG. 1 is a schematic diagram showing a configuration of a scanning electron microscope for observing a surface shape and a foreign substance of a wafer and inspecting defects according to the present invention. The main components of the measurement unit 9 of the scanning electron microscope are a semiconductor wafer 5 as a sample.
Cassette 2 for accommodating and holding the wafer, a cassette fixing table 1 for fixing the cassette 2, a transport mechanism 3 for transporting the wafer 5, an aligner 4 for detecting the size of the wafer, and the wafer. A stage mechanism 7 for moving to the observation position. The semiconductor wafer 5 serving as a sample is a mirror-finished wafer (bare wafer) obtained from a single Si crystal through a cutting, processing, and polishing process, or a wafer with a film on which a silicon oxide film, a dielectric film, or the like is provided. Further, there is a patterned wafer in which a wiring pattern is recorded on a mirror-finished wafer. In FIG. 1, a wafer 5 is stored in a wafer cassette 2.
The wafer cassette 2 is 150 mm (6 inches), 200
The shape and size are substantially determined according to the size of the wafer 5, such as 8 mm (8 inches) and 12 mm (300 mm). The wafer cassette 2 is placed on a cassette fixing table 1 for holding and fixing the wafer cassette. The cassette fixing table 1 is used as a single fixing table for the wafer cassette 2 for 300 mm, 200 mm and 150 mm. The wafer 5 in the cassette 2 is taken out by the wafer transfer mechanism 3 installed beside the cassette fixing table 1. A vacuum suction port 3b is attached to the upper surface of the robot hand 3a attached to the tip of the transfer mechanism 3, and the lower surface of the wafer 5 is suction-held by the vacuum suction port 3b. Therefore, the wafer 5 is transferred by the transfer mechanism 3 without falling from the robot hand 3a. The wafer 5 is taken out of the cassette 2 by the transfer mechanism 3 and transferred to the aligner 4. A suction port 4a is attached to the aligner 4, and the lower surface near the center of the wafer 5 is vacuum-sucked by the suction port 4a.

The wafer rotates around the suction port 4a, and the size of the wafer 5 is automatically determined by the optical detector 4b. At the same time, the position of the orientation flat or the notch of the wafer 5 is detected by the optical detector 4b,
It is adjusted so that it always has a fixed direction. Aligner 4
The wafer 5, the orientation of which is determined by the above, is transported by the transport mechanism 3 onto the sample stage 6 fixed on the stage 7 and placed thereon. The sample stage 6 is an electrostatic chuck, and sucks the wafer by electrostatic force. Vacuum suction using a vacuum other than the electrostatic chuck is also possible for the suction of the wafer 5. The stage 7 includes a three-axis XYZ or a five-axis stage in which XYZ is rotated and tilted.

The wafer 5 in the sample observation chamber 8 is moved to a wafer observation position by the stage 7, and the surface shape and foreign matter of the wafer 5 and defect inspection are performed by the wafer observation means. The transport mechanism 3, the aligner 4, and the stage 7 in the measuring section 9 communicate with the control section 10. Since the cassette 2 differs depending on the size and type of the wafer 5, the position where the wafer is taken out or returned by the transfer mechanism 5 needs to be stored in accordance with each cassette 2. By storing in advance the wafer take-out position in the control unit according to the type of each cassette 2, even if the cassette 2 is replaced, the transport mechanism 3 does not collide with the wafer 5 and is not damaged, so that the cassette 2 can be surely removed. The wafer 5 can be taken out of the wafer 2. The control unit 10 includes the transport mechanism 3, the aligner 4, and the stage 7.
While storing and controlling a series of sequence operations of
It communicates with the computer 11 and receives instructions from the computer 11. The computer 11 is connected to a display 12 serving as a display and a storage device 13. The display 12 displays an image observed by the electron microscope, and the image is stored in the storage device 13 as data.

[0014]

FIG. 2 is a schematic diagram showing a first embodiment of the present invention, and is a detailed explanatory view of the cassette fixing table 1 and the cassette 2 described in FIG. For example, with a scanning electron microscope, 30
When observing a 0 mm wafer, the 300 mm wafer cassette 14 is
It is placed on top and fixed. The 300 mm wafer cassette 14 contains 13 300 mm wafers 16 and 2
There are 5 pieces, the shape is cylindrical,
The shape is different from that of the conventional cassette 15 up to 200 mm wafer. This 300 mm wafer cassette 14
Is mounted on the 300 mm shared cassette fixing table 17 on which
Three pins 17a for positioning and fixing the 00 mm wafer cassette 14 are attached. The three pins 17a have conical tips and are arranged at intervals of approximately 120 ° with respect to the centers thereof, and respectively correspond to three V-shaped grooves on the lower surface of the 300 mm wafer cassette 14. Is positioned. The 300 mm shared cassette fixing base 17 is provided with a stepped guide 17b in addition to the three pins 17a. The cassette 15 can be positioned and fixed by pressing the front end or the rear end of the cassette 15 up to a 200 mm wafer against the guide 17b. The guide 17b is divided into two or three in the front and the rear, and has a structure that can be finely adjusted in front, back, left and right, so that even if the size of the cassette 15 up to 200 mm wafer is different, it can be fixed. Become. Although the guide 17b has a convex shape, it may have a concave shape. As described above, the 300 mm shared cassette fixing table 17 has a structure capable of fixing the conventional cassette 15 up to 200 mm wafers in the same manner as the 300 mm wafer cassette 14 can be fixed. That is, a plurality of cassettes of different types of a 300 mm cassette and a cassette up to 200 mm can be shared by one fixed base.

FIG. 3 is a schematic diagram showing a second embodiment of the present invention. The 300 mm cassette fixing stand 19 is
3 mm on the fixing plate in the same manner as the
The pins are arranged at intervals of approximately 120 °. On the other hand, for the cassette / fixing base 18 up to 200 mm, the same guide 18 a as the 300 mm shared cassette fixing base 17 is mounted on a fixing plate.
mm wafer cassette. In addition, 20
The cassette fixed base 18 up to 0 mm has a 300 mm
Three positioning holes 18b are opened at the same positions as the three pins 19a on the dedicated cassette fixing stand 19. Pin 19
a and the positioning hole 18b are fitted so that the positioning hole 18b fits into the pin 19a. That is, when observing the 300 mm wafer 16, the 300 mm dedicated cassette fixing base 19 is used so that the 300 mm wafer cassette 14 can be fixed.
When observing a wafer of 00 mm or less, 200 m
3 so that the cassette 15 up to m wafers can be fixed.
The cassette fixed base 18 up to 200 mm is used by being superimposed on the 00 mm dedicated cassette fixed base 19. In this way, the three pins 19a on the 300 mm cassette fixing base 19 are used for both fixing the 300 mm wafer cassette 14 and positioning and fixing the cassette fixing base 18 up to 200 mm. Furthermore, in order to improve the workability when removing the two fixed bases after they are stacked, a notch 19b is provided at the left and right central part of the cassette fixed base 19 for 300 mm.

FIG. 4 is a plan view showing a third embodiment of the present invention. The 200 mm or 150 mm cassette fixed stand 20 is a cassette fixed stand 1 up to 200 mm.
8 is plate-shaped, and 200 mm or 15 mm
A guide 20a is attached to hold the 0 mm cassette 21. The guide 20a has three parts: front, center, and rear.
The H bar formed on the bottom surface of the cassette 21 is supported by a central guide, and the front and rear guides are configured to fix the front and rear of the cassette 21. The 200 mm or 150 mm cassette fixed base 20 has a 300 mm dedicated cassette fixed base 19 like the cassette fixed base 18 up to 200 mm.
The positioning hole 20b for fitting to the upper pin 19a is 3
Open. That is, when observing a 300 mm wafer 16 in the same manner as the case of the cassette / fixing stand 18 up to 200 mm, the 300 mm dedicated cassette fixing stand 19 is used so that the 300 mm wafer cassette 14 can be fixed. When observing a 150 mm wafer, 200 mm or 150 mm
300m so that the cassette-dedicated fixed base 20 can be fixed
200mm or 15mm
The fixed base 20 for exclusive use of the 0 mm cassette is used by overlapping. In addition, 2
When the 00 mm or 150 mm cassette fixing stand 20 is overlapped, fixing screws 20 c are attached to the four corners of the 200 mm or 150 mm cassette fixing stand 20 to fix both of them, and the four corner screw holes of the 300 mm dedicated cassette fixing stand 19 are fixed. Screw into 19c.

FIG. 5 is a plan view showing a fourth embodiment of the present invention. The cassette for the 300 mm wafer 16 includes a cylindrical 300 mm wafer cassette 14 and a conventional 200 m wafer cassette.
There is a conventional 300 mm wafer cassette 23 having the same shape and a large size as the cassette 15 up to m wafers.
The conventional 300 mm wafer cassette 23 has a capacity of 300 mm.
mm is fixed on the fixed base 22 for exclusive use of the conventional cassette. 3
The fixed stand 22 for the 00 mm conventional cassette is
Similarly to the cassette fixed stand 18 and the fixed stand 20 dedicated to a 200 mm or 150 mm cassette, a guide 22a is provided at the center of the fixed base 18 for holding a conventional 300 mm wafer cassette 23. The guide 22a is divided into a central part and three places on the left and right sides thereof.
It supports the bar and regulates the movement in the front-back direction. Further, the left and right guides are configured to restrict the movement of the cassette 23 in the left and right direction. The 300 mm cassette fixed base 22 has a positioning hole for fitting to the pin 19 a on the 300 mm cassette fixed base 19 similarly to the cassette fixed base 18 up to 200 mm or the 200 mm or 150 mm cassette fixed base 20. 22
b is open at three places. That is, a cylindrical 300 mm
300 mm wafer 16 in wafer cassette 14
When observing the wafer cassette, the 300 mm wafer cassette 14
300mm dedicated cassette fixing base 1 so that
9 to observe the 300 mm wafer 16 in the conventional 300 mm wafer cassette 23, 3
The 300 mm dedicated cassette fixing base 19 is fixed on the 300 mm dedicated cassette fixing base 19 so that the 00 mm conventional cassette dedicated fixing base 22 can be fixed.
mm The fixed base 22 for exclusive use of the conventional cassette is used by overlapping. As described above, even when observing the same 300 mm wafer 16, it is necessary to change the cassette fixing table according to the cassette to be used. However, the above structure allows easy replacement.

FIG. 6 is a schematic diagram showing a fifth embodiment of the present invention. A cassette presence sensor 24 and a cassette size detection sensor 2 on a 300 mm shared cassette fixing base 17
5 is attached. These sensors are of the optical type, but may be of the fiber type or the mechanical type. 300
When the cassette is placed on the mm shared cassette fixing base 17, the presence of the cassette is detected by the cassette presence / absence sensor 24 near the center of the fixing base 17. At the same time, the cassette size at this time is detected by the cassette size detection sensors 25, 26, and 27. For example, in the case of a cassette for a 150 mm wafer, the sensor 25a for the 150 mm cassette near the outer end thereof is used.
Is detected by Similarly, in the case of a 200 mm wafer cassette, it is detected by the 200 mm cassette sensor 25b near its outer end, and in the case of a 300 mm wafer cassette, it is detected near its outer end.
It is detected by the 0 mm cassette sensor 25c.
Cassette size detection sensors 25a, 25b, 25c
Each signal detected by the above is sent to the amplifier 26 and is sent to the CPU 27 after being amplified. The CPU 27 determines the size of the signal according to the operated sensor. The wafer size information is sent from the CPU 27 to the control unit 28, the position information of each wafer in the cassette registered in advance according to the wafer size is called from the memory 28, and the control unit 28 reads the position information according to the position information. The command is sent to the transport mechanism 30. That is, by placing a cassette of an arbitrary size on the 300 mm shared cassette fixing table 17, the size is automatically detected by the cassette size detecting sensor 25, and the wafer in the cassette can be reliably taken out and transported. At the same time, since the presence or absence of the cassette is detected by the cassette presence / absence sensor 24, if the cassette is not placed on the fixed base or is displaced, it is determined that there is no cassette, and the transport mechanism is set to the wafer position. It is possible to warn that there is no cassette without entering the unloading operation. At this time, a 300 mm shared cassette fixing table 17 was adopted as the cassette fixing table, but in addition to the above, the 300 mm dedicated cassette fixing table 19 described above, and the cassette combined fixing table 18 up to 200 mm, 200 mm or 150 m.
The m-cassette fixed base 20 and the 300 mm conventional cassette-dedicated fixed base 22 may be used.

In the above embodiment, the semiconductor wafer observation device is an example of a scanning electron microscope as shown in FIG. 1, but the present invention is not limited to this.
For example, scanning probe microscope, optical microscope, laser microscope, wafer foreign matter inspection device, wafer surface defect inspection device, wafer appearance inspection device, stylus type surface shape measurement device,
An embodiment of the present invention may be a wafer surface analyzer using an X-ray, an electron beam, or an ion beam.

[0020]

According to the present invention, as described above, in a semiconductor wafer observation apparatus, a 300 mm wafer cassette and a 200 mm or less cassette are commonly used, so that a wafer cassette of a target size can be used. There is an effect that the cassette can be placed and fixed at a predetermined position without replacing the cassette fixing stand. In addition, 200m on the 300mm cassette fixed base
300mm, 200mm,
There is also an effect that a 150 mm cassette can be easily fixed at a predetermined position without replacing the cassette fixing base. Further, the presence of the cassette presence detector has an effect that the transport device can be prevented from being damaged due to malfunction. Furthermore, since the cassette size detector is provided, the cassette size is automatically identified, and the transport mechanism operates to a predetermined position according to each cassette size, so that the wafer can be transported reliably. There is also an effect that can be done.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a scanning electron microscope according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a 300 mm shared cassette fixing base according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing a fixed cassette holder for exclusive use of 300 mm and a fixed base for both cassettes up to 200 mm according to the second embodiment of the present invention.

FIG. 4 is a plan view showing a 300 mm cassette fixed base and a 200 mm or 150 mm cassette fixed base according to a third embodiment of the present invention.

FIG. 5 is a plan view showing a 300 mm cassette fixed base and a 300 mm conventional cassette fixed base according to a fourth embodiment of the present invention.

FIG. 6 is a configuration diagram showing a cassette presence / absence sensor, a cassette size detection sensor and a signal flow thereof according to a fifth embodiment of the present invention.

FIG. 7 is a schematic view showing a conventional cassette fixing base.

FIG. 8 is a schematic diagram showing a cassette for a 300 mm wafer.

[Description of Signs] 1 Cassette fixing stand 2 Cassette 3 Transfer mechanism 3a Robot hand 3b Vacuum suction port 4 Aligner 5 Wafer 6 Sample stand 7 Stage 8 Sample observation room 9 Measuring unit 10 Control unit 11 Computer 12 Display 13 Storage device 14 300 mm wafer Cassette 15 for cassettes up to 200 mm wafer 16 300 mm wafer 17 300 mm shared cassette fixing stand 17a pin 17b guide 18 Cassette combined fixing stand for 200 mm 18a guide 18b Positioning hole 19 300mm dedicated cassette fixing stand 19a Pin 19b Notch 19c Screw hole 20 200mm or 150mm cassette dedicated fixed base 20a guide 20b positioning hole 20c fixed screw 21 200 mm or 150mm cassette 22 300 meters m Fixed stand for conventional cassette 22a Guide 22b Positioning hole 23 Conventional 300mm wafer cassette 24 Cassette presence / absence sensor 25 Cassette size detection sensor 25a 150mm cassette sensor 25b 200mm cassette sensor 25c 300mm cassette sensor 26 Amplifier 27 CPU 28 Control unit 29 Memory unit 30 Transport mechanism

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-82625 (JP, A) JP-A-4-24936 (JP, A) JP-A-11-1613081 (JP, A) JP-A-11- 87460 (JP, A) JP-A-11-67863 (JP, A) JP-A-10-284565 (JP, A) JP-A-6-97259 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) H01L 21/66 H01L 21/68

Claims (4)

(57) [Claims] 1. A wafer for accommodating a plurality of semiconductor wafers.
-The storage container and the wafer storage container are fixed in place.
Wafer holder fixed table and wafer size
Wafer size discriminating mechanism to detect and place wafer
Sample stage and wafers to transfer wafers to any location
The transport mechanism and the wafer transported on the sample stage to the desired position
Moving mechanism for moving the wafer, and observation means for observing the wafer
And a first wafer corresponding to a predetermined wafer container.
Her storage container fixing table, and the predetermined wafer storage container
Supports wafer containers of different shapes or sizes
And detachably mounted on the first wafer storage container fixing table.
Is placed, the semiconductor wafer observation apparatus according to claim Rukoto a and a second wafer container fixing base. 2. The method according to claim 1, wherein the first wafer storage container fixing base is three.
The second wafer for a 00 mm wafer storage container
200mm or 150mm wafer for holding container
2. The semiconductor wafer observation device according to claim 1, wherein one of the storage containers is dedicated . 3. The method according to claim 1, wherein the first wafer storage container fixing base is three.
The second wafer for a 00 mm wafer storage container
200mm and 150mm wafer storage for holding container
2. The semiconductor wafer observation device according to claim 1, wherein the container is shared . 4. The first wafer storage container fixing stand,
The presence / absence of the second wafer storage container fixing table can be determined.
Semiconductor wafer observation device according to claim 1, characterized in that the chromatic detection means.