TW201616599A - Neutralization method for charges on surface of electrostatic chuck - Google Patents

Abstract

The present invention provides a neutralization method for charges on the surface of an electrostatic chuck, comprising: after finishing processing to-be-processed devices in a plasma reaction chamber, removing the to-be-processed devices from the plasma reaction chamber, wherein the to-be-processed devices are fixed to the electrostatic chuck by a first voltage exerted on the electrostatic chuck during the processing procedure of the to-be-processed devices and first charges are accumulated on the surface of the electrostatic chuck during the procedure of fixing the to-be-processed devices to the electrostatic chuck; exerting a second voltage on the electrostatic chuck so as to accelerate the speed of neutralizing the charges of the plasma in the plasma reaction chamber and the first charges accumulated on the surface of the electrostatic chuck, wherein the direction of the second voltage is opposite to the direction of the first voltage. The neutralization method accelerates the neutralization speed of the charges on the surface of the electrostatic chuck, and enhances production efficiency.

Description

Neutralization method of surface charge of electrostatic chuck

The present invention relates to the field of semiconductor processing technology, and in particular, to a method for neutralizing the surface charge of an electrostatic chuck.

In the process of manufacturing an integrated circuit, particularly in plasma etching, physical vapor deposition, chemical vapor deposition, etc., it is necessary to fix, support, and transport the processed device. In order to prevent the moving or misalignment of the processed device during processing, an Electro Static Chuck (ESC) is usually used to fix and support the processed device.

The electrostatic chuck uses electrostatic attraction to fix a processed device such as a wafer. Since the electrostatic chuck uses electrostatic attraction instead of the conventional mechanical means to fix the processed device, it can reduce the irreparable damage caused to the processed device due to mechanical reasons such as pressure and collision in the conventional mechanical mode. Moreover, it is possible to reduce particle contamination caused by mechanical collision.

The electrostatic attractive force for a processed device such as a fixed wafer is generated by a clamping voltage applied to the electrostatic chuck. Under normal circumstances, the surface of the electrostatic chuck is an insulating layer. When the processing time is long or the clamping voltage is high, a large amount of electric charge is accumulated on the surface of the electrostatic chuck. The charge accumulated on the surface of the electrostatic chuck causes the clamping process to be unstable in the processing of the subsequent processing. For example, glass may appear during the etching of the glass wafer on the through-via (TSV) machine. The phenomenon of wafer jumps.

In order to stabilize the processing of the processed device during processing, it is necessary to remove or neutralize the charge remaining in the surface layer of the electrostatic chuck.

In the prior art, the method of removing or neutralizing the charge remaining in the surface layer of the electrostatic chuck is inefficient, which is disadvantageous for improving the production efficiency of the semiconductor processing equipment.

In view of this, the present invention provides a method for neutralizing the surface charge of an electrostatic chuck to accelerate the removal or neutralization efficiency of the charge remaining in the surface layer of the electrostatic chuck, thereby causing the processed device to be electrostatically clamped during processing. The disk is fixed.

In order to solve the above technical problem, the present invention adopts the following technical solution: a method for neutralizing the surface charge of an electrostatic chuck, comprising: after the processing device to be processed is processed in the plasma reaction chamber, the processing device to be processed is Removing the plasma reaction chamber; wherein, during the processing of the processing device to be processed, the processing device to be processed is fixed on the electrostatic chuck by using a first voltage applied to the electrostatic chuck, During the process of fixing the processing device to be processed by the electrostatic chuck, a first electric charge is accumulated on a surface layer of the electrostatic chuck; and a second voltage is applied to the electrostatic chuck to accelerate the plasma reaction a rate of neutralization of the charge in the plasma within the chamber and a first charge accumulated on the surface of the electrostatic chuck, wherein the second voltage is opposite the first voltage.

Optionally, the magnitude of the second voltage is related to the structure of the electrostatic chuck.

Optionally, the magnitude of the second voltage is related to the electrode depth of the electrostatic chuck.

Optionally, the neutralization method is applied during the cleaning of the plasma reaction chamber.

Compared with the prior art, the present invention has the following beneficial effects: during plasma processing of the processing device to be processed, a first voltage is applied to the electrostatic chuck for fixing the processing device to be processed, so that the electrostatic chuck is applied The surface layer accumulates a certain amount of first charge. After the treatment is completed, the processing device to be processed is removed from the plasma reaction chamber, and since the surface of the electrostatic chuck is an insulator, the charge originally accumulated therein remains therein. And applying a second voltage opposite to the first voltage direction to the electrostatic chuck. Under the action of the second voltage, the first charge accumulated on the surface of the electrostatic chuck during the process is rejected, and has a tendency to be away from the electrostatic chuck. And the charge in the plasma within the reaction chamber opposite to the first charge conductivity type is attracted, having a tendency to be close to the electrostatic chuck; therefore, under the action of the second voltage, accumulating in the surface of the electrostatic chuck The charge is opposite to the charge in the plasma opposite to the first charge conductivity type, which helps to speed up the neutralization rate of both. Therefore, the use of the second voltage opposite to the first voltage can improve the removal or neutralization efficiency of the charge in the surface layer of the electrostatic chuck, and is advantageous for improving the production efficiency of the semiconductor processing apparatus.

In order to make the objects, effects and technical solutions of the present invention more clear and complete, the specific embodiments of the present invention are described below with reference to the accompanying drawings.

In the process of processing the processing device, the processing device to be processed is fixed to the electrostatic chuck by a first voltage applied to the electrostatic chuck. If the first voltage is high or the processing time is long, a certain amount of the first electric charge is accumulated on the surface layer of the electrostatic chuck due to the DC insulating property of the surface layer of the electrostatic chuck. If the first voltage is a forward voltage, the conductivity type of the first charge is negative, and if the first voltage is a negative voltage, the conductivity type of the first charge is positive. Figure 1 shows the distribution of accumulated charge on the surface of the electrostatic chuck during the processing of the wafer to be processed by applying a negative voltage to the electrostatic chuck. It can be seen from Fig. 1 that when a negative voltage is applied to the electrostatic chuck, a certain amount of positive charge is accumulated on the surface of the electrostatic chuck, and a certain amount is accumulated on the wafer fixed on the electrostatic chuck. Positive charge.

Since the surface layer of the electrostatic chuck is an insulator, the surface layer is usually composed of a ceramic material, and the process of charge accumulation is a very slow process, and the process of charge removal is also very slow. Therefore, when the application of the voltage to the electrostatic chuck is stopped, the charge originally accumulated therein remains therein.

These residual charges may affect the clamping stability of the device to be processed during subsequent processing. In order to ensure the clamping stability of the device to be processed in the subsequent processing and to improve the production efficiency, it is necessary to provide a method capable of quickly neutralizing or eliminating the residual charge on the surface of the electrostatic chuck.

Based on this need, the present invention provides a method of neutralizing the surface charge of an electrostatic chuck. It should be noted that the method for neutralizing the surface charge of the electrostatic chuck provided by the embodiment of the present invention is suitable for the process of cleaning the plasma reaction chamber after removing the processing device to be processed after the processing device is processed.

The specific implementation manner of the method for neutralizing the surface charge of the electrostatic chuck provided by the embodiment of the present invention will be described in detail below with reference to FIG.

2 is a schematic flow chart of a method for neutralizing surface charge of an electrostatic chuck according to an embodiment of the present invention. As shown in FIG. 2, the neutralization method includes the following steps:

S201. After the processing device to be processed is processed in the plasma reaction chamber, the processing device to be processed is removed from the plasma reaction chamber, wherein during processing of the processing device to be processed, The processing device is fixed on the electrostatic chuck by a first voltage applied to the electrostatic chuck, and the surface of the electrostatic chuck is in the process of fixing the processing device to be processed by the electrostatic chuck Accumulated with the first charge:

As described above, since the surface of the electrostatic chuck is an insulator, the rate of charge accumulated therein during processing is slow, so that the processing of the processed device to be processed is stopped after the application of the first voltage to the electrostatic chuck is stopped. After the electrostatic chuck is removed, the charge that originally accumulated in the surface of the electrostatic chuck remains.

As an example, the embodiment of the present invention is described by taking the first voltage as a negative voltage as an example. As shown in FIG. 1 above, the first charge accumulated in the surface layer of the electrostatic chuck is a positive charge under the action of the negative voltage.

S202, applying a second voltage to the electrostatic chuck to accelerate a neutralization rate of a charge in a plasma in the plasma reaction chamber and a first charge accumulated on a surface layer of the electrostatic chuck, wherein The second voltage is opposite to the first voltage:

A second voltage that is opposite to the first voltage is applied to the electrostatic chuck. Since the second voltage is opposite to the first voltage, the direction of the electric field formed in the electrostatic chuck under the action of the second voltage is opposite to the direction of the electric field formed in the electrostatic chuck under the action of the first voltage.

It should be noted that, in the embodiment of the present invention, the magnitude of the second voltage is related to the structure of the electrostatic chuck, for example, related to the electrode depth of the electrostatic chuck. Moreover, the second voltage acts to generate an electric field that is opposite to the electric field generated by the first voltage, and is not used to fix the processing device to be processed, so that the second voltage value does not need to reach a voltage as high as the first voltage value. That is, in the embodiment of the invention, the second voltage value is less than the first voltage value.

Since the first voltage is a negative voltage in the embodiment of the invention, the second voltage opposite to the first voltage is a forward voltage. Therefore, the electric field generated by the second voltage is a forward electric field. Under the action of the forward electric field, the positive electric charge accumulated in the surface layer of the electrostatic chuck is repelled, which has a tendency to be away from the electrostatic chuck, and at the same time, the device to be processed is moved. Except, therefore, there is no isolation between the plasma in the reaction chamber and the electrostatic chuck, and the two are directly adjacent or in contact. Both positive and negative charges are included in the plasma. Since the second voltage produces a positive electric field, the negative charge in the plasma is attracted to the surface near the surface of the electrostatic chuck under the action of the forward electric field. Figure 3 is a graphical representation of the charge distribution in the surface layer of the electrostatic chuck and the charge distribution in the plasma under the action of the second voltage.

Since the surface of the electrostatic chuck is an insulator, the rate of charge movement is very slow, but the negative charge in the plasma can move very quickly under the action of the second voltage, thereby causing positive charge and plasma in the surface of the electrostatic chuck. The negative charges in the vicinity are accelerated, which accelerates the neutralization rate of the positive charge accumulated in the surface layer of the electrostatic chuck and the negative charge in the plasma, so that the charge accumulated in the surface layer of the electrostatic chuck can be quickly eliminated, thereby enabling rapid entry. The next processing process increases productivity.

It should be noted that, in the embodiment of the present invention, the electric field generated by the second voltage is equivalent to the power that provides directional movement for the negative electric charge in the plasma. Under the action of this power, the negative charge in the plasma is rapidly moved in the surface of the electrostatic chuck to neutralize the charge in the surface layer of the electrostatic chuck.

The specific embodiment of the method for neutralizing the surface charge of the electrostatic chuck provided by the embodiment of the present invention. The above embodiment has been described by taking the first voltage as a negative voltage as an example. In fact, as an embodiment of the present invention, the first voltage may also be a forward voltage, in which case the charge accumulated in the surface layer of the electrostatic chuck is a negative charge, and the second voltage is a negative voltage, so that the plasma The positive charge is neutralized with the negative charge in the surface of the electrostatic chuck to achieve the effect of eliminating the negative charge in the surface of the electrostatic chuck.

The above description is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. It should be considered as the scope of protection of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS In order to clearly understand the technical solutions of the present invention, a brief description of the drawings used in describing the embodiments of the present invention will be briefly described below. Obviously, these drawings are only a part of the drawings of the embodiments of the present invention, and those skilled in the art can obtain other drawings without paying progressive work. 1 is a schematic view showing the charge distribution of the surface layer of the electrostatic chuck when the electrostatic chuck holds the processing device to be processed; FIG. 2 is a schematic flow chart of the method for neutralizing the surface charge of the electrostatic chuck provided by the embodiment of the present invention; Schematic diagram of the distribution of charge in the surface of the electrostatic chuck and the plasma when a second voltage is applied to the electrostatic chuck.

Claims (4)

One kind of an electrostatic chuck and a method of surface charges, including: when the processing means to be processed in the plasma reaction chamber after completion of processing, the processing means processing to be removed from the plasma reaction chamber; wherein, During the processing of the processing device to be processed, the processing device to be processed is fixed on the electrostatic chuck by using a first voltage applied to the electrostatic chuck, and the processing to be processed is fixed on the electrostatic chuck During the process of the device, a first charge is accumulated on the surface layer of the electrostatic chuck; a second voltage is applied to the electrostatic chuck to accelerate the charge and accumulation in the plasma in the plasma reaction chamber The neutralization rate of the first charge on the surface of the electrostatic chuck, wherein the second voltage is opposite to the first voltage. The neutralization method of claim 1, wherein the magnitude of the second voltage is related to the structure of the electrostatic chuck. The neutralization method of claim 2, wherein the magnitude of the second voltage is related to an electrode depth of the electrostatic chuck. The neutralization method according to claim 1, wherein the neutralization method is applied to a cleaning process of a plasma reaction chamber.