JPH0637073A - Cleaning method for rear of wafer and etching device used same - Google Patents

Abstract

PURPOSE:To improve etching characteristic through in-plane uniformity especially in an etching process by removing a foreign matter attaching to the rear of a semiconductor wafer. CONSTITUTION:The title device is an etching device having a cleaning process of the rear of a wafer and comprises a wafer cassette for carrying-in, a wafer rear cleaning part 3 to remove a rear foreign matter of a semiconductor wafer 1, a load lock chamber, an etching treatment chamber, a post-treatment chamber, an unload lock chamber and a wafer cassette for carrying-out. In the wafer rear cleaning part 3, the semiconductor wafer 1 is supported by a supporting arm 14, an ionizer 15 for eliminate static electricity is provided thereabove and an evacuation pipe 16 for attraction is arranged in a bottom surface of the semiconductor wafer 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer back surface cleaning technique, and more particularly to a wafer back surface cleaning method capable of improving foreign matter adhering to the wafer back surface before carrying in an apparatus to improve etching characteristics in an etching step. And a technique effective when applied to an etching apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, as a semiconductor wafer etching apparatus, for example, in a plasma etching apparatus, a plasma is generated in an etching chamber by an interaction between a microwave generated from a magnetron in a waveguide and a magnetic field generated by an electromagnet. An etching process is performed by placing a semiconductor wafer on the electrodes installed in the etching chamber.

As a technique similar to this, for example, an etching technique described in "LSI Handbook" P428 to P434, published by the Institute of Electronics and Communication Engineers, November 30, 1984, and the like can be mentioned.

[0004]

However, in the prior art as described above, when foreign matter adheres to the back surface of the semiconductor wafer, the foreign matter floats up on the semiconductor wafer, resulting in deterioration of etching performance. Is occurring. Particularly, when the electrostatic adsorption method is used, there is a problem that electrostatic adsorption cannot be performed.

Therefore, in the etching apparatus, it is desirable to remove such foreign matter on the back surface of the semiconductor wafer and irradiate the surface of the semiconductor wafer with ion energy vertically and uniformly. Particularly, in recent years, the diameter of the semiconductor wafer has been increased, With the miniaturization of integrated circuits, the uniformity of etching characteristics is required.

Therefore, an object of the present invention is to remove a foreign substance adhering to the back surface of a semiconductor wafer, and particularly to use a wafer back surface cleaning method capable of improving etching characteristics due to in-plane uniformity in an etching process. The present invention is to provide an etching apparatus.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

That is, the wafer back surface cleaning method of the present invention is a wafer back surface cleaning method for removing foreign matter adhering to the back surface of a semiconductor wafer, which is for discharging the semiconductor wafer and then exhausting the back surface of the semiconductor wafer. .

The etching apparatus using the wafer back surface cleaning method of the present invention uses the wafer back surface cleaning method to perform the etching process in a state where the foreign matter attached to the back surface of the semiconductor wafer is removed.

[0011]

According to the above-mentioned wafer back surface cleaning method and the etching apparatus using the same, the semiconductor wafer is destaticized and the back surface is evacuated, so that the semiconductor wafer is destaticized to weaken the attraction of foreign matters. As the back surface of the wafer is evacuated, foreign matter having a weaker suction force can be easily removed.

For example, the static electricity of the semiconductor wafer can be removed by using an ionizer, and the foreign matter whose static electricity is removed and the adsorption force is weakened can be removed by suction by exhaust.

Thus, the adhered foreign matter is removed by cleaning the back surface of the wafer before the etching process, and the etching performance is improved by the uniform etching process without lowering the placement accuracy of the semiconductor wafer against the irradiation energy. It will be possible.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an etching apparatus using a wafer back surface cleaning method which is an embodiment of the wafer back surface cleaning method of the present invention, and FIG. 2 illustrates a flow of a semiconductor wafer in the etching apparatus of this embodiment. 2 is a schematic cross-sectional view taken along line III-III of FIG. 2, FIG. 4 is a schematic cross-sectional view showing the wafer back surface cleaning section in the etching apparatus of this embodiment in detail, and FIG. 5 is a wafer back surface cleaning section. It is a flow chart which shows an operating principle.

First, the structure of the etching apparatus of this embodiment will be described with reference to FIG.

The etching apparatus of the present embodiment is, for example, an etching apparatus having a wafer back surface cleaning step, and includes a wafer cassette 2 in which a plurality of semiconductor wafers 1 are housed and a wafer back surface for removing foreign matters on the back surface of the semiconductor wafer 1. The cleaning unit 3, the load lock chamber 4 for loading and unloading the semiconductor wafer 1 in a vacuum state, the etching processing chamber 5 for performing an etching process, the post-processing chamber 6 for performing post-processing after etching, and the processed semiconductor wafer 1 are provided. It is composed of an unload lock chamber 7 which is loaded and unloaded in a vacuum state, and a wafer cassette 8 which stores the processed semiconductor wafer 1.

Each of these components is arranged as shown in FIG. 2, and the semiconductor wafer 1 is transported as shown in FIG.
For example, the transfer robot 9, the load lock chamber 4, the etching processing chamber 5, the post-processing chamber 6, and the unload lock chamber 7 rotate between the wafer cassette 2, the wafer back surface cleaning unit 3, and the load lock chamber 4, respectively. A straight-moving arm 13 conveys from the arms 10 to 12 and the unload lock chamber 7 to the wafer cassette 8.

Further, as shown in FIG. 4, in the wafer back surface cleaning unit 3 which is a feature of the present invention, the semiconductor wafer 1 is held by the supporting arm 14, and the ionizer 15 for removing static electricity is installed on the upper portion thereof, and the semiconductor is further mounted. An exhaust pipe 16 for suction is arranged on the bottom surface of the wafer 1.

Then, the semiconductor wafer 1 is the ionizer 1
The charge is removed by 5 to weaken the adsorption force of the foreign matter, and then the back surface of the semiconductor wafer 1 is exhausted through the exhaust pipe 16 so that the foreign matter is sucked and removed.

Next, the operation of this embodiment will be described.

First, as shown in FIG. 5, the semiconductor wafer 1
Is carried into the wafer back surface cleaning unit 3 from the wafer cassette 2 by the transfer robot 9, and the semiconductor wafer 1 is held by the support arm 14 (step 501). Then, the semiconductor wafer 1 is destaticized by the ionizer 15 to reduce the suction force of the foreign matter adhering to the back surface (step 502).

Further, the foreign matter having the reduced suction force is removed through the exhaust pipe 16 by the suction force of exhaust gas, whereby the back surface cleaning of the semiconductor wafer 1 is completed (step 503). Then, the semiconductor wafer 1 whose back surface has been cleaned is carried out to the load lock chamber 4 by the transfer robot 9 (step 504).

Then, as shown in FIG. 2, the semiconductor wafer 1 carried into the load lock chamber 4 is carried out to the etching processing chamber 5 by the rotating arm 10. By the above method,
Since the semiconductor wafer 1 is carried into the etching processing chamber 5 after the back surface foreign matter is removed, it is possible to perform a stable etching process that is not affected by the back surface foreign matter.

When the etching process is completed, the rotary arm 11 carries the post-treatment chamber 6 into the post-treatment chamber 6 and then the rotary arm 12 into the unload lock chamber 7. Then, the semiconductor wafer 1 carried into the unload lock chamber 7 is pushed out and stored in the wafer cassette 8 by the rectilinear arm 13. As a result, the semiconductor wafer 1 that has undergone the etching process is transported to the next step.

Therefore, according to the etching apparatus of this embodiment, the wafer back surface cleaning unit 3 in which the ionizer 15 and the exhaust pipe 16 are installed is provided in the preceding stage of the etching processing chamber 5, so that the semiconductor wafer 1 is ionized by the ionizer 15. Is used to weaken the adsorption force of the foreign matter and further suction and remove the foreign matter through the exhaust pipe 16, whereby the semiconductor wafer 1 can be prevented from being lifted up during the etching treatment and a uniform etching treatment can be performed.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, with respect to the etching apparatus of this embodiment, the case where static electricity is eliminated by using the ionizer 15 has been described, but the present invention is not limited to the above-mentioned embodiment, and other types of electricity can be eliminated. If so, it is widely applicable.

The structure of the etching apparatus is not limited to the structure shown in FIGS. 1 to 3, and it goes without saying that various structures and arrangements can be changed.

In the above description, the invention mainly made by the present inventor is applied to the wafer back surface cleaning method used in the etching apparatus which is the field of application of the invention. However, the invention is not limited to this.
The present invention can be widely applied to other devices such as a stepper that are affected by adhesion of foreign matter on the back surface of a semiconductor wafer.

[0030]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

That is, since the foreign matter can be removed by removing the electric charge from the semiconductor wafer and removing the foreign matter by exhausting the back surface of the semiconductor wafer, the influence of the foreign matter on the back surface of the semiconductor wafer can be prevented. can do.

Particularly, in the etching process, by cleaning the back surface of the wafer before processing, it is possible to prevent the semiconductor wafer from being lifted and obtain stable etching and uniform etching characteristics.

[Brief description of drawings]

FIG. 1 is a block diagram showing an etching apparatus using a wafer back surface cleaning method which is an embodiment of a wafer back surface cleaning method of the present invention.

FIG. 2 is a schematic plan view illustrating the flow of a semiconductor wafer in the etching apparatus of this embodiment.

FIG. 3 is a schematic sectional view taken along line III-III in FIG. 2 in the present embodiment.

FIG. 4 is a schematic cross-sectional view showing in detail a wafer back surface cleaning unit in the etching apparatus of this embodiment.

FIG. 5 is a flowchart showing the operating principle of the wafer back surface cleaning unit in the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 2 Wafer cassette 3 Wafer back surface cleaning unit 4 Load lock chamber 5 Etching processing chamber 6 Post-processing chamber 7 Unload lock chamber 8 Wafer cassette 9 Transfer robot 10-12 Rotating arm 13 Straight arm 14 Support arm 15 Ionizer 16 Exhaust pipe

Claims (2)

[Claims] 1. A wafer back surface cleaning method for removing foreign matter adhering to the back surface of a semiconductor wafer, wherein static electricity is removed from the semiconductor wafer to weaken the suction force of the foreign material, and then the back surface of the semiconductor wafer is evacuated to remove the foreign matter. A method for cleaning a back surface of a wafer, which comprises removing foreign matters. 2. An etching apparatus using the wafer back surface cleaning method according to claim 1, wherein etching processing is performed in a state where foreign matter attached to the back surface of the semiconductor wafer is removed.