JPH04109619A - Reactive ion etching device - Google Patents

Abstract

PURPOSE:To prevent the corrosion of an etching pattern due to a reaction product by forming an upward inclined lower variable electrode around a lower electrode and askew changing the incident angle of ions. CONSTITUTION:An upward inclined lower variable electrode 12 is formed around a lower electrode 8. The lower variable electrode 12 is also made horizontal and etched in the same manner as the lower electrode 8 on normal etching. A reaction product 21 adheres to the sidewalls of an etching pattern 22 at that time. When the lower variable electrode 12 is inclined upward, ions are pulled by the ion sheath of the surface of the lower variable electrode and bent obliquely, and collide with a slant semiconductor wafer 9. Consequently, the reaction product 21 adhering to the sidewalls of the etching pattern 22 can be removed. Accordingly, the corrosion of the etching pattern 22 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a reactive ion etching apparatus used for manufacturing semiconductor devices, and particularly to an electrode structure.

(Prior Art) A conventional reactive ion etching apparatus used for manufacturing semiconductor devices is shown in FIG. 5. In this figure, an upper electrode 1 is fixed to a chamber 2 and is electrically grounded. The flow rate of the 0 reaction gas is adjusted by a mass flow controller 3, and the reaction gas is introduced into the chamber 2 from a reaction gas inlet 4. The inside of the chamber 2 is supplied with a voltage (10°-1°1.~l O-'mtorj) by a vacuum pump 6 via an exhaust port 5.
The pressure can be adjusted arbitrarily using the conductance valve 7. A lower electrode 8 is provided in the chamber 2 to face the upper electrode 1, and a semiconductor wafer 9 is placed thereon. An RF oscillator (1,356
RF power output at MHz'* or 400 kl (z) 10 is supplied via a matching system 11.

In such a reactive ion etching apparatus, plasma is generated between the upper electrode 1 and the lower electrode 8,
Near the surface of the semiconductor wafer 9, a dark space, a region with a large voltage drop, a so-called ion sheath, is formed.
Ions generated by the plasma discharge are accelerated within the space and collide with the surface of the semiconductor wafer 9. As a result, highly anisotropic etching can be performed on the surface of the semiconductor wafer 9.

(Problem B to be Solved by the Invention) However, in the conventional reactive ion etching apparatus as described above, the wafer state before and after etching is shown in FIGS. Accordingly, there is a problem that the reaction product 21 adheres to the side wall of the etching pattern 22 and cannot be removed.
If AZ (aluminum) 22' is etched as a mask, the reaction product 21 cannot be removed, so when the semiconductor wafer is taken out into the atmosphere, the chlorine in the reaction product 21 reacts with the moisture in the atmosphere. A problem occurred in that HC1 was generated and the M pattern (etched pattern 22) was corroded.

The present invention has been made in view of the above points, and an object of the present invention is to provide a reactive ion etching apparatus capable of removing reaction products adhering to the side walls of an etching pattern during etching.

(Means for Solving the Problems) The present invention provides a reactive ion etching apparatus having an upper electrode and a lower electrode facing each other in a reaction chamber.
A lower variable electrode that is inclined upward is provided around the lower electrode.

(Function) During normal etching, the lower variable electrode is also kept horizontal like the lower electrode. As a result, the ions are shown in Figure 3(a).
, (b), the light is incident perpendicularly to the semiconductor wafer 9 on the lower electrode, and highly anisotropic etching is performed. At this time, reaction products 21 adhere to the side walls of the etching pattern 22. Next, if you want to remove this, make the pole of the lower variable diagonal upward. Then, the ions are pulled by the ion sheath on the surface of this lower variable electrode as shown in Figure 4 (
As shown in a) and (b), it is bent obliquely and collides with the semiconductor wafer 9 obliquely. Therefore, it becomes possible to remove the reaction products 21 adhering to the side walls of the etching pattern 22. By removing this reaction product 21, when the semiconductor wafer is taken out into the atmosphere, HC1 and the like will not be generated and corrode the etching pattern.

Note that even during normal etching, the etching profile can be controlled by tilting the lower variable electrode upward and adjusting the incident angle of ions.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention. As shown in this figure, a reactive ion etching apparatus according to an embodiment of the present invention has a configuration in which a lower variable electrode 12, means for supplying RF power thereto, and means for driving the lower variable electrode are added to the conventional configuration. It has become. Therefore, the additional parts will be described in detail below, and parts that are the same as those in the conventional system will be given the same reference numerals as in FIG. 5, and their explanation will be omitted.

The lower variable electrode 12 is divided into four parts and provided around the lower electrode 8, as shown in the bottom plan view of the chamber (reaction chamber) in FIG. These four lower variable electrodes 12 are
It is insulated and rotatably attached to the lower electric bridge so that it can be changed between the same horizontal position as the lower electrode 8 and an upwardly inclined position.

Further, these four lower variable electrodes I2 can be independently controlled by the bushing bins I3 provided correspondingly to the above-mentioned two.
Two canes! ! (However, the oblique angle is arbitrary). The pnosbin 13 has the same configuration as an air cylinder, and the air control box 14
It is operated by air controlled by In addition, RF power is supplied to the lower variable electrode I2 by a cable connected through the inside of this pin 13, and the RFt power value supplied to the lower variable electrode 2 and the lower electrode 8 are The RF power value can be varied with the RF distributor I5.

Such a reactive ion etching apparatus can remove reaction products attached to the sidewalls of an etching pattern after a normal etching operation. The normal etching operation and reaction product removal operation will be described in detail below.

During normal etching, the lower variable electrode 12 is also kept horizontal like the lower electrode 8, as shown in FIG. 3(a). As a result, the ions are perpendicularly incident on the semiconductor wafer 9 on the lower electrode 8, as shown by the arrows in FIGS. 3(a) and 1(b), and highly anisotropic etching is performed. At this time, the reaction product 21 adheres to the side wall of the etching pattern 22. Next, when removing this, as shown in FIG.
The lower variable electrode 12 is sequentially tilted upward as shown in FIG. Then, the ions are pulled by the ion sheath on the surface of the oblique lower variable electrode 12 and are bent obliquely as shown by the arrow in FIG.
collide with Therefore, the reaction products 21 attached to the side walls of the etching pattern 22 can be removed. There are four lower variable electrodes 12 around the lower electrode 8.

By sequentially tilting the four lower variable electrodes 12 upward and returning them horizontally, the semiconductor wafer 9 has a 360"
Ion incidence occurs obliquely from the direction, and the reaction product 21 can be reliably removed. And this reaction product 2
By removing 1, when the semiconductor wafer 9 is taken out into the atmosphere, HC1 etc. are generated and the etching pattern 2 is removed.
2 will not corrode.

The appropriate time for one lower variable electrode 12 to tilt upward and return to the horizontal position is about 10 to 30 seconds.

Furthermore, during normal etching, the same RF power is supplied to the lower variable electrode 12 and the lower electrode 8, but when removing reaction products, the RF power supplied to the lower variable electrode 12 and the lower electrode 8 is By changing the value using the RF distributor 15, it is possible to control the degree of bending of ions and the degree of removal of reaction products.

Furthermore, when removing reaction products, the etching pattern 22
To prevent the sidewalls from being excessively etched,
The gas system is mainly composed of Ar and some C! It is better to use a gas with added .

Further, although the above explanation is about the removal of reaction products, it is also possible to control the etching profile by tilting the lower variable electrode 12 upward and adjusting the incident angle of ions even during normal etching.

(Effects of the Invention) As detailed above, according to the reactive ion etching apparatus of the present invention, the lower variable electrode that is tilted upward is provided around the lower electrode, so that the incident angle of ions can be changed diagonally. This makes it possible to remove reaction products adhering to the side walls of the etching pattern during etching, and to prevent corrosion of the etching pattern caused by the reaction products. Further, even during normal etching, the etching profile can be controlled by adjusting the ion incidence angle using the lower variable electrode.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the reactive ion etching apparatus of the present invention, Fig. 2 is a bottom plan view of the chamber of the above-mentioned apparatus, and Fig. 3 shows the state of the electrodes and the incident state of ions during normal etching. 4 is a front view showing the electrode state and ion incident state during reaction product removal, FIG. 5 is a configuration diagram of a conventional reactive ion etching apparatus, and FIG. 6 is before etching and after etching. It is a front view showing a wafer state. 1... Upper electrode, 2... Chamber, 8... Lower electrode, 12... Lower variable electrode.

Claims (1)

[Claims] What is claimed is: 1. A reactive ion etching apparatus having an upper electrode and a lower electrode facing each other in a reaction chamber, characterized in that a lower variable electrode that is inclined upward is provided around the lower electrode.