JPH04333228A - Dry-etching device - Google Patents

Abstract

PURPOSE:To reduce the dispersion in etching rate and etching shape during the dry-etching step of a semiconductor device. CONSTITUTION:A taper part 5a is provided on the fitting part of an etched semiconductor wafer 3 of the electrode protective cover 5 of the title dry-etching device and then the deformation in the boundary between plasma and ion sheath layers is diminished so as to enhance the surface evenness of said semiconductor wafer 3 thereby displaying the characteristics of the title dry-etching device.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor devices, and more particularly to a dry etching apparatus that improves the in-plane uniformity of a workpiece during dry etching.

0002

2. Description of the Related Art FIG. 4 is a cross-sectional view of a wafer mounting part during dry etching processing in a reactive ion etching apparatus, which is an example of a conventional dry etching apparatus. 8 is a metal electrode for generation, 8 is an electrode protection cover made of quartz or carbon-based resin to protect the metal electrode 1 from being etched during dry etching, 3 is a semiconductor wafer to be etched mounted on this electrode protection cover 8. , 4 are plasma/ion sheath layer boundaries that occur during dry etching.

FIG. 5 is a cross-sectional view of a wafer mounting part of another conventional dry etching apparatus. In this figure, 1 is a metal electrode, 3 is a semiconductor wafer to be etched, and 9 is a cover of the electrode protection cover 8 of FIG. This is a drop-in type electrode protection cover in which a hole is formed in the mounting area of the etched semiconductor wafer 3 to form a drop-in part 2 so that the semiconductor wafer 3 to be etched comes into contact with the metal electrode 1.

0004

Next, a method of processing a semiconductor device using a conventional dry etching apparatus will be explained. In FIG. 4, when high-frequency power is applied to the metal electrode 1 and the electrode (not shown) above the semiconductor wafer 3 to be etched in a vacuum containing a trace amount of etching gas, the plasma-ion sheath layer boundary Plasma is generated above 4, and an ion sheath layer is generated below, so that the plasma/ion sheath layer boundary 4 is positively charged and the metal electrode 1 is negatively charged. Here, ions generated in the plasma generation layer are accelerated in the direction of the metal electrode 1 by the electric field of the ion sheath layer, collide with the semiconductor wafer 3 to be etched, react with the object to be etched on the semiconductor wafer 3 to be etched, and generate The objects are separated from the semiconductor wafer 3 to be etched, and the etching process progresses. When dry etching is performed using this method, the shape of the plasma-ion sheath layer boundary 4 is deformed depending on the thickness of the semiconductor wafer 3 to be etched. For this reason, ions collide in a non-vertical direction, particularly in the peripheral area of the semiconductor wafer 3 to be etched, so that variations in the etching rate and etching shape increase.

Furthermore, in order to improve the etching anisotropy, as shown in FIG.
Drill a hole in the electrode protection cover at the installation site and insert the drop-in part 2.
The semiconductor wafer 3 to be etched is brought into direct contact with the metal electrode 1 using a drop-in electrode protection cover 9 formed with a
A method is used to improve the straightness of ions in etching gas. However, even in this example, variations in the etching rate and etching shape in the peripheral area of the semiconductor wafer 3 to be etched are unavoidable.

As described above, in the conventional dry etching method using reactive ions, the plasma/ion sheath layer boundary 4 in the peripheral area of the semiconductor wafer 3 to be etched is deformed, so that the ions of the etching gas are transferred to the semiconductor wafer 3 to be etched. However, there were problems such as non-perpendicular collision, resulting in variations in etching speed and etching shape.

The present invention has been made in order to solve the above-mentioned problems, and improves the shape of the etched portion of the semiconductor wafer to be etched and reduces the variation in etching speed and etched shape within the wafer surface. The purpose of the present invention is to obtain a semiconductor device with a high temperature.

[0008]

[Means for Solving the Problems] In a semiconductor device according to the present invention, a tapered portion is formed in the depressed portion of the electrode protection cover on the metal electrode on the side of the semiconductor wafer to be etched, descending from the outside toward the depressed portion. This is what I did.

[0009]

[Function] In the semiconductor device of the present invention, by providing a tapered portion around the depressed portion of the electrode protection cover on the side of the semiconductor wafer to be etched, deformation of the plasma/ion sheath layer boundary during etching is reduced, and the semiconductor device to be etched is By colliding the etching gas ions perpendicularly to the wafer, variations in the etching rate and shape within the plane are reduced, and uniformity within the plane is improved.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a wafer mounting part of a reactive ion etching apparatus showing an embodiment of the present invention, in which 1 is a metal electrode, 5 is an electrode protection cover, and a taper angle θ1 is formed around the depressed portion 2. A tapered portion 5a that descends from the outside toward the depressed portion 2 is formed. Reference numeral 3 denotes a semiconductor wafer to be etched, which is mounted in the depressed portion 2 . 4 is the plasma/ion sheath layer boundary.

FIG. 2 is a diagram showing another embodiment of the present invention.
is a removable electrode protection cover, which is provided with a tapered portion 6a having a taper angle θ2 around the depressed portion 2, and this tapered portion 6a is removable. Note that the other parts are the same as in FIG. 1.

FIG. 3 is a diagram showing still another embodiment of the present invention. Reference numeral 7 denotes a removable electrode protection cover with height adjustment. In addition to being provided with a taper portion 7a of the formula, the height t of the position of the semiconductor wafer 3 to be etched can be adjusted.

Next, the operation of each embodiment will be explained. FIG. 1 is a cross-sectional view during the dry etching process, in which a tapered portion 5a with a taper angle θ1 is formed during the dry etching process.
By using the electrode protection cover 5 equipped with the above, the deformation of the plasma/ion sheath layer boundary 4 is reduced compared to the conventional one, and the etching gas ions collide almost perpendicularly to the semiconductor wafer 3 to be etched even in the periphery. Variations in speed and etching shape are reduced compared to conventional methods.

FIG. 2 also shows a semiconductor wafer 3 to be etched.
Etching speed under conditions such as the object to be etched, etching gas, and electrode spacing. In order to minimize the variation in shape, the electrode protection cover 6 is removable and has a tapered part 6a that allows the taper angle θ2 to be changed in various ways so that the optimum taper angle θ2 can be selected. Conditions are optimized.

Furthermore, in addition to changing the taper angle θ1 of the electrode protection cover 5 of the embodiment shown in FIG. 2, FIG. 7 removable taper part 7
Equipped with an electrode protection cover 7 with height adjustment that can be controlled by the thickness t of a, the etching speed and etching shape of the semiconductor wafer 3 to be etched can be controlled, and variations in these can be reduced. This makes it possible to determine the taper angle and height of the electrode protection cover.

In the above embodiment, the tapered cross section of each electrode protection cover was a straight line, but it may also be a quadratic curve, a hyperbola, an exponential curve, or the like. Further, the material of the semiconductor wafer 3 to be etched may be any of compound semiconductors such as Si, GaAs, and InP. Further, the object to be etched may be the semiconductor wafer 3 to be etched, an oxide film, a nitride film, a metal thin film, etc. on the wafer.

Furthermore, the electrode protective cover may be made of any material that provides the same effect, such as quartz or various carbon-based resins. In addition, dry etching equipment includes RIE,
Any type of apparatus such as plasma etching may be used.

[0018]

[Effects of the Invention] As explained above, according to the present invention,
Since a tapered part is provided in the part of the electrode protection cover of the dry etching equipment into which the semiconductor wafer to be etched falls, it is possible to reduce variations in the etching speed and shape of the semiconductor wafer to be etched, and to improve the in-plane uniformity of various surfaces to be etched. There are effects that can be achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a wafer mounting portion of a dry etching apparatus for explaining an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a wafer mounting portion of a dry etching apparatus for explaining another embodiment of the present invention.

FIG. 3 is a sectional view of a wafer mounting portion of a dry etching apparatus for explaining still another embodiment of the present invention.

FIG. 4 is a cross-sectional view of a wafer mounting portion of a conventional dry etching apparatus.

FIG. 5 is a cross-sectional view of a wafer mounting portion of a dry etching apparatus for explaining another conventional example.

[Explanation of symbols]

1 Metal electrode 2 Dropping part 3 Semiconductor wafer to be etched 4 Plasma/ion sheath layer boundary 5　Electrode protection cover 6. Removable electrode protection cover 7. Electrode protection cover with height adjustment

Claims (1)

[Claims] Claims: 1. A dry etching apparatus comprising an electrode protection cover having a recessed part, in which a semiconductor wafer to be etched is mounted on the recessed part and etched; A dry etching apparatus characterized by having a tapered part that descends toward the indented part.