JPH04100256A - Treater provided with electrostatic suction mechanism and separation of materiel to be sucked - Google Patents

Abstract

PURPOSE:To promote the removal of a residual polarization and to make possible efficiently a suction and separation of a materiel to be sucked by a method wherein the title treater is provided with a means, which applies a DC voltage of a reverse polarity to each of electrodes coming into contact to the conductive and flat plate- shaped material to be sucked via an insulating layer and makes the polarity invert, and the treater is provided with a heating means for heating the insulating layer. CONSTITUTION:A DC power supply 4, which applies a direct current to an electrostatic chuck 6, is provided with a change-over means 41 and the polarity of an applying voltage to electrodes 1 and 2 is made to invert. A vacuum chamber 7 is provided with an infrared-transmitting window 9 in opposition to a semiconductor wafer 51 and an infrared lamp 8 is installed. After a DC or high-frequency voltage is applied between the chuck 6 and the chamber 7 to generate plasma and an RIE treatment is performed, the polarity of the applying voltage to the electrodes 1 and 2 is inverted by the means 41 and at the same time, after infrared rays are irradiated on the wafer 51 for a prescribed time through the window 9, the DC power supply 4 is cut off. Thereby, a residual polarization in an insulating layer 3 disappears and the wafer 51 is easily separated from the chuck 6.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a method for removing an object to be attracted from an electrostatic attraction mechanism for transporting, supporting, or fixing a semiconductor substrate or the like.

The purpose is to facilitate the detachment of the object to be attracted by promoting the removal of residual polarization in the insulating layer constituting the electrostatic attraction mechanism.

At least two electrodes that are in contact with one surface of a conductive flat plate-like object through an insulating layer and to which DC voltages of opposite polarity are applied, and switching means for reversing the polarity of the DC voltages to the electrodes. an electrostatic adsorption mechanism having;
A processing apparatus is configured to include means for heating the insulating layer, and a DC electrode of a predetermined polarity is applied to the electrode to remove the attracted object from the electrostatic attraction mechanism.

The method for detaching the object to be attracted is configured such that the insulating layer is heated for a predetermined period of time by the heating means while applying the DC voltage inverted by the switching means to the electrode. especially,
An infrared light source is used as the heating means, and the flat object is irradiated with infrared rays through a light transmission window provided opposite to the flat object.

[Industrial application field]

The present invention relates to a method for detaching an object to be attracted from an electrostatic attraction mechanism for transporting, supporting, or fixing a semiconductor substrate or the like.

For example, in the manufacture of semiconductor devices, an electrostatic adsorption device (electrostatic chuck) is used as a mechanism to transport a semiconductor wafer into a processing device and to support and fix it in a predetermined position and orientation within the processing device. ing.

[Conventional technology]

FIG. 4 shows the basic configuration of an electrostatic chuck.

Electrodes I and 2 are embedded in a resilient insulating layer 3, and are placed on an object 5 such as a silicon wafer or the like on the insulating layer 3, facing the electrodes 1 and 2. For example, when a positive (+) voltage is applied to electrode 1 and a negative (-) voltage is applied to electrode 2, as shown in FIG. Charges of opposite polarity corresponding to are induced, and the object to be adsorbed 5 is attracted by the Coulomb force acting between these charges and the electrodes 1 and 2.

If the target object 5 is subjected to high-temperature treatment such as plasma treatment in this state, a strong attraction force remains even after the DC power supply 4 is cut off, and the target object 5 is moved from the electrostatic chuck to the target object 5.
cannot be easily removed.

The reason for this is thought to be that dielectric polarization occurs in the insulating layer 3 due to the application of the DC voltage, and this polarization remains even after the DC power source 4 is cut off, as shown in FIG. 3(b). This residual polarization makes it difficult to detach the semiconductor wafer,
There is a problem that the adsorbed object 5 may be damaged if an excessive external force is applied to make it detach.

In addition, since the remanent polarization has hysteresis characteristics, 9
This may affect the suction force for the semiconductor wafer to be processed next, and may cause problems in which stable suction cannot be achieved.

On the other hand, it takes a long time for the polarization to disappear naturally. Therefore, in order not to reduce the throughput of manufacturing semiconductor devices, it is necessary to promote the disappearance of bipolarization.

[Problem to be solved by the invention]

Conventionally, it has been proposed that the voltages applied to the electrodes 1 and 2 are reversed to hasten the disappearance of the residual adsorption force as described above. (Unexamined Japanese Patent Publication No. 59-67629) However, is the above method effective for removing the surface charge accumulated on the surface of the insulating layer 3 and the adsorbed body 5? However, the effect was not sufficient.

SUMMARY OF THE INVENTION An object of the present invention is to provide a processing apparatus and a detachment method that are equipped with an electrostatic chuck that promotes the removal of residual polarization as described above and can stably and efficiently attract and detach semiconductor wafers and the like.

[Means to solve the problem]

The above object includes at least two electrodes that are in contact with one surface of a conductive plate-shaped object to be attracted via an insulating layer, a DC power supply for applying a DC voltage of opposite polarity to each of the electrodes, and a DC power supply for applying a DC voltage of opposite polarity to each of the electrodes. A processing apparatus according to the present invention, comprising an electrostatic adsorption mechanism having a switching means for reversing the polarity of the DC voltage, and a means for heating the insulating layer, or the heating means. is an infrared light source, or a container that accommodates the object to be adsorbed and can be evacuated, and a light-transmitting device provided in the container facing the object to be processed. With the window.

The processing apparatus according to the present invention, further comprising: the light source installed outside the container so as to be able to irradiate the object to be processed with the infrared rays through the light transmission window.

Alternatively, when the attracted object is removed from the electrostatic attraction mechanism by applying a DC electrode of a predetermined polarity to the electrode, while applying the DC voltage reversed by the switching means to the electrode. This is achieved by the method for detaching the object from the electrostatic adsorption mechanism in the processing apparatus according to the present invention, which includes the step of heating the insulating layer by the heating means for a predetermined period of time.

[For production]

When detaching the object to be attracted, the DC voltage applied to the electrostatic chuck is reversed and the insulating layer of the electrostatic chuck is heated. As a result, the residual polarization in the insulating layer disappears within a short time, making it easier for the adsorbed object to detach. As a result, not only the efficiency of the treatment process is improved, but also damage to the adsorbed body due to external force required for detachment is reduced, and the yield of the treatment process is improved.

〔Example〕

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

In the following drawings, the same parts as in the previously shown drawings are designated by the same reference numerals.

FIG. 1 is an explanatory diagram of the principle of the present invention, and as shown in FIG. 1(a), a semiconductor wafer 51 as an object to be attracted is shown.

A plasma treatment such as reactive ion etching (RIE) 9 is performed while the device is fixed by an electrostatic chuck consisting of electrodes 1 and 2, an insulating layer 3, and a DC power supply 4.

As shown in the figure, apply 10 voltage to electrode 1.

Is dielectric polarization generated within the insulating layer 3 when a voltage is applied to the electrode 2 and the semiconductor wafer 51 is attracted?
The insulating layer 3 and the semiconductor wafer 5 are exposed to plasma,
The temperature rises to about 100°C. As a result, the same figure (b)
As shown in FIG. 2, even if the DC power source 4 is disconnected after plasma processing, the above polarization remains strongly in the insulating layer 3, making it difficult to remove the semiconductor wafer 51 from the electrostatic chuck.

Conventionally, the voltages applied to the electrodes 1 and 2 were reversed when the semiconductor wafer 51 returned to room temperature, but residual polarization could not be removed with good reproducibility.

In the present invention, as shown in FIG. 2C, the polarity of the DC voltage applied to electrodes 1 and 2 is reversed and
For example, the semiconductor wafer 51 is irradiated with infrared radiation. This infrared rays pass through the semiconductor wafer 51 and are absorbed by the insulating layer 3. As a result, the insulating layer 3 is heated, and residual polarization is removed in a short time.

The semiconductor wafer 51 can be easily removed. In addition.

As a result, infrared rays are absorbed by the semiconductor wafer 51.

The same applies to the method of indirectly heating the insulating layer 3 to the semiconductor wafer 51 whose temperature has increased.

The relationship between the heating temperature of the insulating layer 3 and the infrared irradiation time required to eliminate the residual polarization to such an extent that the semiconductor wafer 51, which is fixed by an electrostatic chuck facing downward in the vertical direction, can be detached by its own weight is shown in Fig. 2. It is. In addition, the wavelength of the main peak spectrum of the irradiated infrared rays is 1 to 15 μm.
within the range of As shown in the figure, the residual polarization can disappear in a shorter time as the temperature increases. This effect can be obtained at a heating temperature of several tens of degrees Celsius to 100"C, and the semiconductor wafer 51
The characteristics of the elements formed in the insulating layer 3 of the electrostatic chuck
There is no risk of deterioration. Further, the heating time may be about 1 to several minutes, and there is no fear that the throughput of the process will be significantly reduced.

FIG. 3 is a schematic diagram illustrating the general structure of an embodiment of the RIE processing apparatus according to the present invention.1 Inside the vacuum chamber 7 made of, for example, stainless steel, there is an electrostatic chuck 6 having the structure shown in FIG. is installed.

A semiconductor wafer 51 is supported and fixed by the electrostatic chuck 6 . The DC power supply 4 for applying a DC voltage to the electrostatic chuck 6 is provided with a switching means 41, and the polarity of the voltage applied to the electrodes 1 and 2 can be reversed. Further, the vacuum chamber 7 is provided with an infrared transmitting window 9 made of Zn5 (zinc sulfide crystal), for example, and facing the semiconductor wafer 51. Vacuum chamber 7
An infrared lamp 8 is installed outside. .

A predetermined etching gas is introduced while evacuating the inside of the vacuum chamber 7, and a direct current or high frequency voltage is applied between the electrostatic chuck 6 and the vacuum chamber 7 to generate plasma to perform RIB.
After the processing, the switching means 41 reverses the polarity of the voltage applied to the electrodes 1 and 2, and after irradiating the semiconductor wafer 51 with infrared rays for a predetermined period of time through the infrared transmitting window 9, the DC power source 4 is turned off. do.

As a result, residual polarization in the insulating layer 3 disappears.

The semiconductor wafer 51 can be easily removed from the electrostatic chuck 6.

Note that the heating method for the insulating layer 3 is not limited to the above-mentioned infrared irradiation, but other methods such as heat generation by a resistance heating element placed around the electrostatic chuck may also be used.

〔Effect of the invention〕

According to the present invention, residual polarization in the insulating layer of an electrostatic chuck can be removed with good reproducibility, and RIE of semiconductor wafers
This has the effect of improving the throughput of processing steps such as wafers, etc., and also reduces damage to objects to be attracted, such as semiconductor wafers, due to excessive external force when detached from an electrostatic chuck, thereby improving the yield of processing steps. It goes without saying that the present invention is not limited to RIE processing and processing equipment in the manufacture of semiconductor devices, but is applicable to other processing and equipment that use electrostatic chucks.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the principle of the present invention. FIG. 2 is a graph showing the relationship between heating temperature and time required to remove residual polarization. FIG. 3 is a schematic structural diagram of an embodiment of a processing device according to the present invention. FIG. 4 is an explanatory diagram of conventional problems. In fig. 1 and 2 are electrodes, 3 is an insulating layer. 4 is a DC power supply, 5 and 6 are electrostatic chucks. 8 is an infrared lamp. 41 is a switching means. It is. is the adsorbed object. 7 is a vacuum chamber. 9 is an infrared transmitting window. 51 is the semiconductor wafer Figure 1 Ta 1 Tomeka Sugi 1 Muneki 1 n' FT 540F Eye 1 Boku and Inken■ Monritsusha 2 Figure ε Honchuaki 1 less Iwari kei! The belly of Futai example! Sideways' conventional e
. 1 point explanatory diagram

Claims (4)

[Claims] (1) at least two electrodes in contact with one surface of a conductive plate-shaped object to be attracted via an insulating layer; a DC power source for applying a DC voltage of opposite polarity to each of the electrodes; A processing apparatus comprising: an electrostatic adsorption mechanism having a switching means for reversing the polarity of a DC voltage; and a means for heating the insulating layer. (2) The processing apparatus according to claim 1, wherein the heating means is an infrared light source. (3) a container that accommodates the adsorbed object and can be evacuated;
a light transmitting window provided in the container facing the object to be processed; and a light source installed outside the container so as to be able to irradiate the object with the infrared rays through the light transmitting window. 3. The processing device according to claim 2, further comprising: (4) When a DC electrode of a predetermined polarity is applied to the electrode to remove the attracted object from the electrostatic attraction mechanism, the DC voltage reversed by the switching means is applied to the electrode. 2. The method for removing the object from the electrostatic attraction mechanism in a processing apparatus according to claim 1, further comprising the step of heating the insulating layer for a predetermined period of time by the heating means.