JPH09246366A - Electrostatic adsorption device and electron beam drawing apparatus using the same - Google Patents

Abstract

Kind Code: A1 Abstract: An electrostatic adsorption device for an electron beam drawing apparatus that suppresses the potential of the wafer surface, does not affect the trajectory of the electron beam, and further suppresses the generation of foreign matter as much as possible. There is provided an electron beam drawing apparatus including the. SOLUTION: In order to reproducibly ground the wafer to be attracted, a conducting jig is brought into contact with the side surface or the back surface of the wafer, and then driven diagonally by a piezoelectric element. At this time, the drive amount of the conduction jig is controlled while measuring the potential of the wafer. Furthermore, an exhaust means is provided near the conduction jig. [Effect] By confirming the potential of the wafer and establishing conduction, it is possible to surely ground the wafer. Further, by controlling the drive amount of the conduction jig by using the piezoelectric element, even a wafer having a different surface state can be suppressed to a minimum scratch, and optimal grounding with less generation of foreign matter becomes possible. Further, it is possible to remove foreign matter generated during cutting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic adsorption device, and more particularly to an electrostatic adsorption device used in an apparatus for irradiating a sample with charged particles such as an electron beam drawing apparatus.

[0002]

2. Description of the Related Art In an apparatus using an electron beam, for example, an electron beam drawing apparatus, a sample is moved with acceleration / deceleration when drawing the sample. Therefore, it is necessary to have a function of holding the sample so that the sample does not shift from a predetermined position. Further, the wafer that has undergone a process such as film formation has a shape along a convex shape or a concave shape of several tens of μm. Therefore, it is necessary to correct this warp to a flat surface in terms of drawing accuracy.

In response to this requirement, a reduction projection exposure apparatus (stepper) intended for the same pattern exposure is performed under atmospheric pressure, and therefore the sample can be corrected by vacuum suction. However, this method cannot be adopted in an electron beam drawing apparatus performed in a vacuum atmosphere or a scanning electron microscope (SEM) for the purpose of length measurement and appearance inspection. Therefore, an electrostatic adsorption device utilizing electrostatic force is used. This electrostatic chucking device secures a chucking force by applying a voltage between a wafer that is a sample and a dielectric material that constitutes a sample holder to generate an electric charge.

However, a very hard insulator such as an oxide film is deposited on the silicon wafer to be adsorbed. Therefore, it is necessary to remove or destroy this insulating film to establish continuity with the wafer. Conventionally, a conductive diamond needle or the like is used to scratch the surface of the wafer for electrical continuity. Further, as described in JP-A-7-302746, a mechanism for bringing a sharp edge of a superhard material into contact with the side surface of the wafer to establish conduction is provided.

[0005]

However, even if a sharp object is simply pressed against the side surface of the wafer, a contact resistance is generated between the wafer and the wafer, and the wafer cannot be surely brought to the ground potential. The unnecessary electric field near the wafer generated by the potential of the wafer causes a serious problem that the orbit of the electron beam deflected and obliquely irradiated on the wafer is bent.

In addition, the method of scratching the wafer surface as described above because of too much continuity to ensure continuity leads to a large amount of destruction of the insulating film, that is, a large amount of foreign matters, and a reduction in yield. Further, the wafer may be scratched more than necessary, and when exposed to a high temperature in a later process, the wafer may be damaged by thermal stress.

The object of the present invention is to reduce the contact resistance as much as possible and ground it with good reproducibility, thereby suppressing the potential of the wafer to the extent that it does not affect the electron beam trajectory, and further suppressing the generation of foreign matter as much as possible. An object is to provide an electroadsorption device.

[0008]

To solve the above problems, the following means were used.

In order to ground the wafer, a means for driving the conducting jig in the thickness direction of the wafer and in the horizontal direction with the rear surface is provided after the conducting jig is brought into contact with the side surface or the rear surface of the wafer. More specifically, a means for driving the blade of the leading end of the conduction jig so as to cut obliquely with respect to the sample is provided. Further, a means for controlling the conduction jig while measuring the potential of the wafer and driving it until the potential becomes equal to or less than a specified value is provided. Further, an exhaust means for removing cutting chips (foreign matter) generated when cutting the wafer is provided in the vicinity of or inside the conduction jig.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

FIG. 1 is a schematic view of an electrostatic attraction device showing an embodiment of the present invention. In the figure, an electrode 3 is embedded in a dielectric 2 which is an adsorption surface of a wafer 1, and is connected to an adsorption DC power supply 4. This dielectric 2 is installed on a conductive base pallet 5,
Is grounded so that the potential becomes zero. A conductive jig 7 having a sharp blade surface is pressed against the side surface of the wafer 1 by utilizing the elastic force of the spring 6. This conduction jig 7
The shape is as shown in FIG. In the figure, the jig base material 7a is made of titanium having non-magnetic and conductive properties, and after the conductive diamond is brazed to the jig base material 7a, the cutting edge 7b is cut by grinding and polishing. I am configuring. Further, a piezoelectric element 8 is attached to the conduction jig 7, and an operation of cutting the side surface of the wafer 1 by a driving power source 9 can be performed. This operation is performed by the controller 11 according to the measurement value of the surface electrometer 10 installed on the wafer 1.
Control. The exhaust port 25 is provided below the connecting jig 7.
Is provided, and suction is always performed when the conduction jig 7 is operated. Hereinafter, the operation of the present embodiment will be described. A conducting jig 7 is pressed against the wafer 1 placed on the suction surface of the dielectric 2 from the side surface. At this time, the wafer 1 is fixed at the regular position by the stopper 12 around the wafer 1. Here, the switch 13 is closed and a voltage is applied to the dielectric 2 so that the wafer 1 is attracted to the attracting surface of the dielectric 2. Since a leakage current flows through the wafer 1, the conduction jig 7 and the wafer 1
A potential is generated on the wafer 1 due to the contact resistance with. For example, if the leakage current is 200 μA and the contact resistance is 5 kΩ, it means that a potential of 1 V is generated on the surface of the wafer 1. This potential is measured by the surface electrometer 10,
The piezoelectric element 8 attached to the conduction jig 7 is driven until the potential becomes equal to or lower than the set potential. As a result, the conductive jig 7 breaks the insulating film on the side surface of the wafer 1 and reaches the silicon substrate, so that the wafer 1 can be reliably grounded.

FIG. 3 is a schematic view of an electron beam drawing apparatus equipped with the electrostatic attraction device of the present invention. In the figure, the electron gun 14
The electron beam 15 emitted from the laser beam is shaped by the aperture 16 and each lens 17, and the beam trajectory is controlled by the deflecting plate 18 to a desired drawing position. Further, the base pallet 5 and the dielectric 2 are installed on the stage 19, and the drawing position of the wafer 1 sucked and held by the base pallet 5 is controlled by the movement of the stage 19. The base pallet 5 is provided with the above-mentioned conduction jig 7, and the potential of the wafer 1 can be suppressed to about 100 mV.
As a result, the influence on the trajectory of the electron beam is reduced as compared with the conventional device, and the drawing accuracy can be improved.

Further, the present invention is not limited to the electron beam drawing apparatus.
It is also effective in a device using an electron beam, such as a length measuring SEM or a visual inspection device. FIG. 4 is a schematic view of an appearance inspection device equipped with the electrostatic attraction device of the present invention. In the figure,
Similar to the electron beam drawing apparatus described above, the electron beam 15 emitted from the electron gun 14 is narrowed down by each lens 17, and the trajectory is deflected to a desired position by the deflecting plate 18. Then, when the wafer 1 is irradiated with the electron beam 15, secondary electrons are emitted. The secondary electrons are detected by the detector 20, and then the image processing system 21 performs a comparison operation to detect a minute defect. Further, the base pallet 5 and the dielectric 2 are installed on the stage 19 as in the electron beam drawing apparatus described above. This base pallet 5 is also equipped with the above-mentioned conduction jig 7 to keep the potential of the wafer 1
It can be suppressed to about 100 mV. As a result, the influence on the trajectory of the electron beam is reduced as compared with the conventional device, and the detection accuracy can be improved.

FIG. 5 is a schematic view of an electrostatic attraction device showing another embodiment of the present invention. In the figure, the above-mentioned conduction jig 7 is arranged on the back surface of the wafer 1. This continuity jig 7
A piezoelectric element 8 is obliquely attached to, and a driving power source 9 cuts the back surface of the wafer 1. At this time, the holding jig 22 presses the wafer 1 from above so that the wafer 1 does not float up. The holding jig 22 has a curved surface shape so that the wafer 1 is not scratched. The operation of the conduction jig 7 is controlled by the controller 11 based on the potential difference measured by the voltmeter 24 by the needle-shaped probe 23 pressed against the back surface of the wafer 1. At this time, the variation in the contact resistance between the wafer 1 and the probe 23 does not affect the measurement value because the input impedance of the voltmeter 24 is large and the measurement current is small. The structure of the dielectric 2 and the basic operation of this embodiment are similar to those of the embodiment of FIG.

FIG. 6 is a detailed view of a conductive jig showing another embodiment of the present invention. In the drawing, the exhaust port 2 is provided in the conduction jig 7.
5 is provided, which penetrates the conduction jig 7 and is connected to the suction pump 26. When the suction pump 26 operates, the gas around the exhaust port 25 is sucked through the path indicated by the arrow 27. As a result, even if a foreign substance is generated around the conduction jig, it can be removed by suction. Therefore, the wafer can always be adsorbed in a clean atmosphere, and the yield can be improved.

[0016]

According to the present invention, the potential on the wafer surface can be made constant and small, and as a result, the drawing and detection accuracy can be improved. Further, the yield of production can be improved by minimizing the destruction of the insulating film and sucking and removing the generated foreign matter.

[Brief description of drawings]

FIG. 1 is a schematic view of an electrostatic attraction device showing an embodiment of the present invention.

FIG. 2 is a detailed view of a conduction jig showing an embodiment of the present invention.

FIG. 3 is a schematic view of an electron beam drawing apparatus equipped with the electrostatic attraction device of the present invention.

FIG. 4 is a schematic view of an appearance inspection device equipped with the electrostatic attraction device of the present invention.

FIG. 5 is a schematic view of an electrostatic attraction device showing another embodiment of the present invention.

FIG. 6 is a detailed view of a conduction jig showing another embodiment of the present invention.

FIG. 7 is a schematic view of a conventional electrostatic attraction device.

[Explanation of symbols]

1 ... Wafer, 2 ... Dielectric, 3 ... Electrode, 4 ... Adsorption DC power supply, 5 ... Base pallet, 6 ... Spring, 7 ... Conductive jig, 8
... Piezoelectric element, 9 ... Driving power source, 10 ... Surface electrometer, 11
... controller, 12 ... stopper, 13 ... switch, 1
4 ... Electron gun, 15 ... Electron beam, 16 ... Aperture, 1
7 ... Lens, 18 ... Deflection plate, 19 ... Stage, 20 ... 2
Secondary electron detector, 21 ... Image processing system, 22 ... Holding jig,
23 ... Probe, 24 ... Voltmeter, 25 ... Exhaust port, 26 ...
Suction pump, 27 ... Suction path.

Front page continuation (72) Inventor Kazunori Ikeda 882 Ichimo Ichi, Hitachinaka City, Ibaraki Hitachi Ltd. Measuring Instruments Division (72) Inventor Yoshimasa Fukushima 882 Ichige, Hitachinaka City Ibaraki Hitachi Ltd. Measuring Instruments (72) Inventor Issui Mizuno 882 Ichimo, Hitachinaka City, Ibaraki Prefecture Hitachi Ltd. Measuring Instruments Division (72) Inventor Hiroyuki Ito 882, Ichige, Hitachinaka City, Ibaraki Hitachi Ltd. Measuring Instruments Business Inside (72) Inventor Tokurorou Saito 1-280, Higashi Koigokubo, Kokubunji, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd.

Claims (7)

[Claims] 1. An electrostatic adsorption device for adsorbing and holding the sample on the dielectric by applying a voltage between the sample and the dielectric, wherein the sample is provided around the electrostatic adsorption device. An electrostatic chucking device is characterized in that a conducting jig is arranged so that a force acts diagonally thereto. 2. The electrostatic attraction device, wherein means for measuring the potential of the sample is provided, and the drive amount of the conduction jig is controlled by using a piezoelectric element so that the potential becomes ± 500 mV or less. The electrostatic attraction device according to claim 1. 3. In the electrostatic attraction device, the conducting jig has a structure having a sharp blade surface, and the conducting jig is driven in the thickness direction of the sample while being pressed against the side surface of the sample. The electrostatic attraction device according to claim 1 or 2. 4. The electrostatic adsorption device according to claim 2, further comprising, as a potential measuring means for the sample, a static electricity measuring device or a surface potential meter capable of measuring without contacting the sample. Electrostatic adsorption device. 5. The electrostatic attraction device, further comprising, as a potential measuring means of the sample, at least one contactor other than the conducting jig, and a voltmeter capable of measuring by contacting with the sample. The electrostatic attraction device according to claim 2. 6. An electrostatic attraction device for attracting and holding the sample on the dielectric by applying a voltage between the sample and the dielectric, wherein an exhaust port is provided near the conducting jig. An electrostatic adsorption device, characterized in that an exhaust means connected to the exhaust port is provided. 7. An electron beam drawing apparatus using the electrostatic attraction device.