JPH05315435A - Specimen retainer - Google Patents

Abstract

PURPOSE:To exhibit stable attractive force in a wide temperature range, and cause no damage to an object to be retained, by constituting a plurality of attraction parts different in resistivity. CONSTITUTION:When a wafer is loaded, a load chamber and a carrier chamber 36 connect only a voltage applying switch 10a of a chuck 3 for normal temperature with 10b, and a wafer 1 is attracted and retained, which is carried to a process chamber 3!. When the retaining is released, the switch 10a is turned to the 10c side. When the processing in the process chamber 31 is low temperature etching, only a voltage applying switch 12a of a chuck 5 for lower temperature is connected with 12b, and the wafer 1 is attracted and retained, which is carried to the next process chamber 32. Chucks 3, 4, 5, which are dielectric constituting an electrostatic attraction equipment, are composed of materials different in resistivity. Thereby a specimen retainer can be obtained which has stable attractive force in a wide range from a low temperature to a high temperature, without causing the breakdown of a semiconductor element due to an excessive current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chucking device for fixing and holding a sample such as a conductor or a semiconductor such as a silicon wafer to be subjected to microfabrication.

[0002]

2. Description of the Related Art In a process of performing processing such as etching or film formation of a sample such as a semiconductor wafer, the sample is transported at high speed in a vacuum, and therefore, it is necessary to fix and hold the sample in a transport mechanism. Furthermore, when etching or forming a film, it is necessary to fix and hold the device at a predetermined position. In particular,
When processing a fine pattern on a semiconductor wafer, it is required to securely fix the wafer on a flat surface for the purpose of flattening the wafer and improving thermoelectric efficiency. Traditionally,
As a sample holding means for such an application, an electrostatic adsorption device that can be used even in a vacuum and that can generate an adsorption force on the entire back surface of a wafer is used. This electrostatic adsorption device is configured by laminating an electrode plate and a dielectric, and generates a potential difference between the electrode plate and the sample, thereby generating a Coulomb force and adsorbing and holding the sample on the dielectric.

Regarding such an electrostatic attraction device, for example, Japanese Patent Application Laid-Open No. 3-194948, Applied Mechanical Engineering 1989, 5
There is a citing example on page 128 of the monthly issue.

FIG. 9 shows an electrostatic attraction device disclosed in Japanese Patent Laid-Open No. 3-194948. That is, Japanese Patent Laid-Open No. 3-19494
In the example disclosed in JP-A-8, in order to prevent the dielectric film on the surface of the electrostatic adsorption device from being destroyed due to the difference in thermal expansion with the internal electrode in a wide temperature range from low temperature to high temperature, As a dielectric film on the surface, an insulating layer having a coefficient of thermal expansion almost equal to that of the electrode is formed.

[0005]

By the way, when performing etching or film forming such as sputtering or CVD in a semiconductor manufacturing process, a wafer as a sample and an electrostatic chuck holding the wafer are used. In addition to a room temperature atmosphere, the device is used for low temperature etching, for example, minus 6
The film is exposed to a low temperature atmosphere of 0 ° C., and in a high temperature atmosphere of, for example, about 400 to 600 ° C. in a film forming process such as sputtering and CVD. As the semiconductor process, as shown in FIG. 1, wiring processing by a so-called multi-chamber method in which various process chambers are added to a transfer chamber provided with one transfer device is mainstream. That is, it is necessary for one sample holding device to exhibit a stable adsorption force in a wide temperature range from low temperature to high temperature as described above. However, the disclosed example lacks consideration in terms of providing a stable adsorption force in a wide temperature range.

In the electrostatic adsorption type sample holding device, ceramics are used as a dielectric for adsorbing the sample. In many cases, ceramics used for electrostatic attraction are as shown in FIG.
The resistance changes depending on the temperature.
Further, as the resistance changes, the dielectric constant also changes, and the adsorption force also changes. Therefore, even if it has a stable adsorption force at room temperature, the resistivity increases and the adsorption force decreases at low temperature, and the resistivity decreases and the adsorption force increases at high temperature, but the current flows too much and the semiconductor There is a risk of damaging the element.

Therefore, in the disclosed example of Japanese Patent Laid-Open No. 3-194948, although it is possible to use a wide temperature range in terms of mechanical strength, it is considered that a stable adsorption force is obtained in a wide temperature range. Not enough and not enough.

An object of the present invention is to provide an electrostatic adsorption type sample holder which exhibits a stable adsorption force in a wide temperature range from low temperature to high temperature and which does not damage the element of the wafer to be held. To provide.

[0009]

The object of the present invention is to make the dielectric material of the electrostatic adsorption type sample holding device a plurality of materials having different resistivities, such as alumina having a resistivity of 10 ¹³ Ωcm to 10 ¹⁶ Ωcm and a resistivity of 10 ⁹ Ωcm. Ωcm to 10 ¹¹ Ωcm silicon carbide, 10 ⁷ Ωc
A voltage generator that is made of three types such as silicon carbide of m 10 to 10 ¹⁰ Ωcm, etc., has electrodes independently for each of these materials having different resistivities, and creates a potential difference between each electrode and the holding object, This is achieved by providing a switch for cutting off and applying the voltage, and effectively by adding a control circuit for switching the switch based on the information on the ambient temperature or the dielectric temperature.

[0010]

The ceramic, which is a dielectric used for electrostatic attraction, preferably has a resistivity of 10 ⁹ Ωcm to 10 ¹¹ Ωcm because it has a large attraction force. However, since the resistivity of ceramics changes with temperature, the permittivity also changes and the adsorption force also changes with changes in temperature. That is, even if the adsorption power is stable at room temperature, the resistivity increases and the adsorption power decreases as the temperature decreases, and the resistivity decreases as the temperature increases and the current flows too much.

In the sample holding device of the present invention, the dielectric for holding and holding the object to be held is formed from a plurality of materials having different resistivities, which have the same suction surface, and are provided on the opposite side of each suction surface. Electrodes are independently provided on the surface so that a voltage can be applied independently. That is, it is composed of a plurality of adsorption portions having different resistivities. Therefore, the plurality of adsorption portions have a resistivity of 10 ⁹ Ωcm to 10 ¹¹ Ω with respect to a plurality of environmental temperatures in which the sample holding device is used.
It is composed of multiple materials with a cm size, and by operating the changeover switch to use the adsorption part suitable for the operating temperature according to the operating temperature, stable adsorption force is generated in a wide temperature range from low temperature to high temperature. be able to.

[0012]

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

1 to 3 are views showing first and second embodiments of the present invention. FIG. 1 is a plan view of a semiconductor manufacturing apparatus seen from above, and FIG. 2 is an electrostatic adsorption type sample holding apparatus. Is a circuit diagram viewed from above, and FIG. 3 is a sectional view thereof.

First, referring to FIG. 1, the operation of the proposed sample holder in the semiconductor manufacturing apparatus will be described. Figure 1
In the multi-chamber type semiconductor manufacturing apparatus shown in FIG. 1, the wafer 1 stored in the cassette case 27 in the loader chamber 29 is held in the transfer chamber 36 by the electrostatic adsorption type sample holding attached to the tip of the transfer robot 35. The apparatus is fixedly held by the apparatus 2, and the transfer robot 3 sequentially performs processing such as transfer, etching, and film formation from the processing chambers 31 to 34. Then, after all the processing is completed, the wafer 1 is returned to the cassette case 28 in the unload chamber 30. In this case, for example, when one of the processes performed in 31 to 34 is low temperature etching, the wafer 1 may be cooled to, for example, -60 degrees, and one of the processes is a film forming process such as CVD or sputtering. In this case, the wafer 1 is heated from 400 degrees to 600 degrees, and the temperature inside the processing chamber becomes extremely high accordingly. As described above, the sample holder 2 must hold the wafer 1 in a very wide temperature range.

Next, the operation of the sample holding device will be described with reference to FIGS. In these figures, 1 is a held object that is fixedly held and conveyed, such as a semiconductor wafer,
Reference numeral 2 is a transfer arm body. Reference numerals 3, 4 and 5 are dielectrics that constitute the electrostatic attraction device, and are made of materials having different resistivities. For example, in this embodiment, 3 is a high temperature chuck. For example, the resistivity at room temperature is 10 ¹³ Ωcm to 10 ¹⁶ Ω
Alumina or the like having a size of 10 ⁹ Ωcm to 10 ¹¹ Ωcm is formed at a high temperature of 300 ° C to 400 ° C. Further, 4 is a chuck for room temperature, for example, silicon carbide having a resistivity of 10 ⁹ Ωcm to 10 ¹¹ Ωcm at room temperature, and 5 is a chuck for low temperature. For example, silicon carbide having a resistivity of 10 ⁷ Ωcm to 10 ¹⁰ Ωcm at room temperature and 10 ⁹ Ωcm to 10 ¹¹ Ωcm at a low temperature of -30 ° C to 60 ° C.
Shall be That is, both are made of a dielectric material having a resistivity of 10 ⁹ Ωcm to 10 ¹¹ Ωcm at the operating temperature.
These dielectrics are adhered and integrally formed by an insulating adhesive 14, and the fixed holding surface of the held object is processed into the same plane. 6, 7 and 8 are dielectrics 3 having different resistivities 3,
Electrodes formed on the surface opposite to the adsorption surface of 4, 5
Reference numeral 9 is a power source for applying a voltage, 10a, 11a and 12a are power source changeover switches, and 13 is a ground. Also,
Reference numeral 15 is a pin that conducts electricity from the wafer 1.

In the electrostatic adsorption type sample holding device thus constructed, when loading a wafer, the load chamber and the transfer chamber 36 are at room temperature, so only the voltage application switch 10a of the room temperature chuck 4 is used. 10b, the wafer 1 is suction-held, and the wafer 1 is transferred to the next process chamber 31. In this case, the high temperature chuck has too high resistance at room temperature to generate sufficient adsorption force, and the low temperature chuck has low resistance, which causes too much current to flow and damages the wafer to be held, resulting in damage to the voltage. Is not applied. When releasing the holding at the next stage of the process chamber, the changeover switch 10a may be changed over to the side 10c which is connected to the ground. In the next process of the process chamber 31, if the process is, for example, low temperature etching, the wafer 1 is, for example, minus 60.
May be chilled occasionally. When the wafer is taken out from the low temperature etching chamber and is transferred to the next process chamber, the temperature of the sample holding device 2 itself also drops. In this case, the voltage application switch 12a of the low temperature chuck 4
Only the wafer 12 is connected to the wafer 12b, and the wafer 1 is suction-held and transferred to the next process chamber 32. In this case, a high temperature chuck and a room temperature chuck have too high resistance to generate a sufficient attracting force, and therefore a voltage is not applied and the chuck is not operated. Further, in the next process of the process chamber 31, if the process is, for example, a film forming process such as CVD or sputtering that requires a high temperature, the wafer 1 is heated from 400 degrees to 500 degrees, and accordingly. The temperature inside the processing chamber also becomes extremely high. Therefore, the high temperature chuck 5
The voltage application switch 13a is connected to 13b only, the wafer 1 is adsorbed and held, and is transferred to the next process chamber 33. In this case, no voltage is applied to the chuck for normal temperature and low temperature because the resistance is too low and the current flows too much to damage the wafer as the held object. In this manner, the changeover switch is operated according to the atmosphere of each process chamber so as to use the adsorption portion suitable for the atmosphere temperature, and the wafer 1 is sequentially processed from the processing chambers 31 to 34.
Processing such as transportation, etching, and film formation is consistently performed, and after all processing is completed, the wafer is returned to the cassette case 28 in the unload chamber 30.

As described above, according to this embodiment, the resistivity increases due to the temperature decrease, the attraction force decreases, and the resistivity decreases due to the temperature increase, that is, the semiconductor element is not destroyed by the overcurrent. Moreover, it is possible to obtain a sample holding device having a stable adsorption force in a wide temperature range from low temperature to high temperature. Further, although not shown, a backup battery and a switch are added in parallel to each voltage application circuit, and measures are taken in case of an emergency by operating the switch so that voltage is supplied from the battery in case of power failure. Is possible.

In the present embodiment, an example in which a plurality of materials having different resistivities are adhered and integrally formed with an insulating adhesive 14 is used, but a dielectric is formed by materials having different resistivities. It suffices that an electrode is independently provided on the surface opposite to the holding surface so that a potential difference can be independently generated between the electrode and the holding object, and the invention is not particularly limited to this type. For example, as shown in FIG. 4, there is a space 16 between the respective materials, and the surface opposite to the suction surface may be connected by an insulating adhesive 14, or, for example, as shown in FIG. As described above, the materials may be in close contact with each other.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The holding device main body is the same as that of the embodiment shown in FIGS. 2, 3 and 4, but each electrode 6, 7, 8 and ground 1
Switch 1 that connects 5 and 5 in parallel to disconnect and apply voltage
0, 11, and 12 are independently provided and have a common power source. That is, the voltage can be applied to all the electrodes with one power source.

A fifth embodiment of the present invention is shown in FIG. In the present embodiment, instead of installing the conducting portion 15, two electrodes 6a, 6b, 7a, 7b, 8a, 8b are independently provided on the surface opposite to the holding surface made of materials having different resistivities. It is provided and configured to apply voltage independently between the electrodes,
This is a so-called bipolar type electrostatic adsorption method.

A sixth embodiment of the present invention is shown in FIG. In the sample holding device of this embodiment, the holding device main body has the same configuration as that of the embodiment shown in FIGS. 2 to 5, but it is further measured by temperature measuring means for measuring the ambient temperature in which the sample holding device is used. It is equipped with a control device for switching the switch depending on the temperature. In the present embodiment, an example in which the thermocouple 17 is used as the temperature measuring means and the temperature of the held sample body is measured is shown. Based on the measured temperature information, the control device 19 issues a command to use an appropriate adsorption portion for the temperature environment in which the sample holding device is placed, and the relays 10, 21, 22 switch the switches 10, 21, Switching between 11 and 12. In this case, in a semiconductor manufacturing apparatus having a wide temperature environment as shown in FIG. 1, a stable suction force can be generated and an automatic operation can be efficiently performed.

FIG. 8 shows a seventh embodiment of the present invention. A sample is used for etching or film formation in each of the processing chambers 31 to 34 of the semiconductor manufacturing apparatus as shown in FIG. This is an example applied to a holding device that holds the. In such a process, an electrostatic adsorption type sample holding stage is used to reduce foreign matters due to sputtering from the wafer fixing jig, to flatten the wafer to be held, and to improve the heat transfer efficiency. Be done. In this case, since the operating temperature is determined by the process performed in each processing chamber, that is, the low temperature for low temperature etching and the high temperature for CVD or sputtering, the dielectric material having the resistivity corresponding to the temperature of each process in advance. The sample holder should be made in.
By the way, in the sample holding device placed in such a processing chamber, in order to reduce the adhesion of floating dust, the wafer 1 is moved to the position shown in FIG.
It is often installed so as to hold the surface of the wafer 1 vertically, as shown in FIG. Therefore, although not shown, if the cooling device for cooling the wafer or the heater for heating the wafer fails, or if a power failure occurs, an accident such as dropping of the wafer is possible. In this embodiment, when normal processing is performed, only the switch 10 is connected, and a voltage is applied only to the electrode 7 to generate an attractive force on the dielectric 4. Then, when the wafer cooling device or the wafer heating heater fails and the sample holding device approaches room temperature, a switch 11 is connected to the electrode 6 to generate an attraction force on the auxiliary room temperature dielectric 3. Hold the wafer. At this time, it is desirable to disconnect the switch 11. Further, the wafer can be held by connecting the switch 24 so as to apply the voltage from the battery 23 at the time of power failure.

Such switching of the switches is preferably performed by the temperature sensor and the switch switching relay as shown in the previous embodiment, and the control device for controlling them.

In the present embodiment, an example in which the present invention is applied to the sample holding device in the processing chamber as an emergency measure is taken, but when a temperature range from low temperature to high temperature is required in one process Can be applied to the same configuration as the embodiment shown in FIGS.

[0025]

According to the present invention, it is possible to provide a good sample transfer and sample holding device which exhibits a stable adsorption force in a wide temperature range from low temperature to high temperature and does not damage the elements of the wafer. it can.

[Brief description of drawings]

FIG. 1 is a plan view of a semiconductor manufacturing apparatus showing the embodiment of the present invention.

FIG. 2 is a circuit diagram showing an embodiment of the present invention.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a third embodiment of the present invention.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 6 is a circuit diagram showing a fifth embodiment of the present invention.

FIG. 7 is a circuit diagram showing a sixth embodiment of the present invention.

FIG. 8 is a circuit diagram showing a seventh embodiment of the present invention.

FIG. 9 is a sectional view showing a conventional example.

FIG. 10 is a temperature characteristic diagram of dielectric ceramics for electrostatic attraction.

[Explanation of symbols]

3, 4, 5 ... Dielectric, 6, 7, 8 ... Electrode, 9 ... Power supply, 1
0, 11, 12, ... Switches.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location H01L 21/302 B 8518-4M H02N 13/00 D 8525-5H

Claims (1)

[Claims] 1. An electrostatic adsorption type sample holding device in which an electrode plate and a dielectric are laminated, and a potential difference is generated between the electrode plate and the held object to adsorb the held object to the dielectric. A dielectric is formed of a plurality of materials having different resistivities, and an electrode is independently provided on each of the materials having different resistivities on the surface opposite to the holding surface of the dielectric, and the electrode and the holding object. A sample holding device characterized in that a voltage generator for independently generating a potential difference between the two and a switch for cutting and applying the voltage are provided.