JPH012322A - plasma etching equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Structure of the Invention] (Industrial Application Field) The present invention relates to a plasma etching apparatus for etching a workpiece such as a semiconductor wafer using plasma.

(Prior Art) A parallel plate type plasma etching apparatus is known as a conventional plasma etching apparatus. The parallel 14-plate plasma etching apparatus generates plasma by applying a high-frequency electric field to the etching gas introduced between the parallel plate electrodes, and accelerates the generated plasma.
This is for etching a workpiece placed at h°. However, when attempting to increase the etching rate in a conventional parallel plate plasma etching apparatus by increasing the high frequency voltage applied between the parallel plate electrodes to increase ion acceleration, high-speed ions collide with the surface to be processed, resulting in physical damage. There was a problem in that the crystals of the object to be processed were damaged due to sputtering. Another problem is that when the pressure of the etching gas is increased to increase the etching speed, the accelerated ions and neutral particles collide, and the sides of the etching groove are etched by the collided neutral particles, making it impossible to form fine patterns. was there.

Further, as another conventional plasma etching apparatus, there is a microwave plasma etching apparatus. A microwave plasma etching apparatus generates plasma by applying microwaves to an etching gas to which a magnetic field is applied, and etches the object to be processed using the generated plasma. However, in conventional microwave plasma etching equipment, the generated plasma moves along the lines of magnetic force of the applied magnetic field and escapes from the vicinity of the workpiece, so the plasma density does not increase sufficiently and high-speed etching is not possible. There was a problem.

(Problems to be Solved by the Invention) As described above, it is not possible to perform high-speed etching without damaging the workpiece with the conventional parallel plate type plasma etching apparatus, and even with the conventional microwave plasma etching apparatus. The object to be processed could not be etched at high speed.

The present invention has been made in consideration of the above circumstances, and it is an object of the present invention to provide a plasma etching apparatus that can perform high-speed etching without damaging a workpiece.

[Structure of the invention]

(Means for solving the problem) The above purpose is to provide a vacuum container into which etching gas is introduced,
A mounting plate provided in a vacuum container on which an object to be processed is placed, a microwave applying means for applying microwaves to the etching gas in the vacuum container, and a microwave applying means for applying microwaves to the etching gas in the vacuum container, This is achieved by a plasma etching apparatus characterized in that it is equipped with a magnetic field applying means for applying a confining magnetic field to the plasma in the vicinity of the mounting plate.

(Function) Since the present invention is constructed as described in 1- below, the etching gas is excited by microwaves, and the generated plasma is forced into the vicinity of the mounting plate by the magnetic field applying means. , this confined plasma is used to perform etching.

(Example) A plasma etching apparatus according to a first example of the present invention is shown in FIG. A vacuum vessel 1 of this plasma etching apparatus has a quartz tube 2 provided on its inner surface. Vacuum capacity'r
t1 and the quartz tube 2 have an etching chamber in the center, and convex portions are formed on the top, bottom, left and right of this etching chamber. Etching gas is introduced into the quartz tube 2 from a gas inlet pipe (not shown), and exhausted from a gas exhaust pipe (not shown). A mounting table 4 for mounting a wafer 5 is housed in a convex portion on the lower side of the etching chamber of the quartz tube 2.

In this example, the etching gas was heated using microwaves (2,45
GllZ) to generate plasma.

A magnetron 10 is provided for generating microwaves. In order to introduce the microwave from the magnetron 10 into the vacuum vessel 1, the waveguide 3 is connected to the magnetron 1.
0 to the upper protrusion of the vacuum container 1. Furthermore, two vertically divided coils 6A and 6B are provided on the outside of the vacuum container 1 to generate a magnetic field. Coil 6A.

As shown in FIG. 1, the surface 6B is substantially parallel to the surface of the mounting table 4, and its axis substantially coincides with the central axis of the wafer 5.

Plasma is generated in a long convex portion of the vacuum chamber 1 extending above the etching chamber. That is, plasma is generated by the action of the magnetic field generated by the coil 6A and the high frequency electric field generated by the microwave on the etching gas in the convex portion.

The magnetic field generated by the coils 6A, 6B is
When a current flows in the same direction through B, the dashed dotted line Mmi in Figure 1
It becomes a mirror magnetic field as shown by rror, and the coil 6A,
When a current in the opposite direction is passed through 6B, the two-dot chain line Mcu appears in Figure 1.
This results in a cusp magnetic field as shown by sp. Both the mirror magnetic field and the cusp magnetic field function as a confining magnetic field to confine the generated plasma in the etching chamber. That is, the generated ions move along the lines of magnetic force, but since a mirror magnetic field or cusp magnetic field is formed around the etching chamber, the plasma is confined and the ion concentration is lowered to the mounting table 4.
The height can be increased in a nearby etching chamber.

The operation of this embodiment will be explained. First, etching gas is introduced into the quartz tube 2 of the vacuum container 1. Current is passed through the coils 6A and 6B to generate a magnetic field, and the magnetron 10 generates microwaves to cause the magnetic field and high frequency electric field to act on the etching gas to generate plasma.

The generated plasma is transferred to the mounting table 4 by the confining magnetic fields MIllror and Mcusp applied by the coils 6A and 6B.
A high-density plasma is formed near the mounting table 4 while being confined in a nearby etching chamber, and the surface of the wafer 5 is etched by this plasma.

As described above, according to this embodiment, plasma is generated by the action of microwaves and a magnetic field, and the generated plasma is confined in the area near the mounting table by the confining magnetic field.
Etching can be performed at high speed by increasing the ion density of the plasma used for etching.

A plasma etching apparatus according to a second embodiment of the invention is shown in FIG. Components that are the same as those in the embodiment shown in FIG. 1 are given the same reference numerals, and their explanations will be omitted. This embodiment differs from the first embodiment in the connection position of the waveguide 3 for applying microwaves. That is, in the first embodiment, the waveguide 3 was connected to the convex part on the upper side of the vacuum vessel 1, but in this embodiment, the waveguide 3 is connected to the convex part on the left side of the vacuum vessel 1. The points are different. As described above, in this embodiment, the etching gas is excited by microwaves applied from the side of the etching chamber, and plasma is generated.

In this way, microwaves can generate plasma even when applied from any direction outside the measuring instrument, and the generated plasma is confined and densified by the confining magnetic field.
Etched at high speed. In particular, as in this example, the horizontal h°
By applying microwaves from the top, it is not necessary to provide a magnetron at the top, and the height of the entire device can be reduced.

A plasma etching apparatus according to a third embodiment of the present invention is shown in FIG. Components that are the same as those in the embodiment shown in FIG. 1 are given the same reference numeral 7 and their explanations will be omitted. This embodiment is characterized in that the electrode 8 is provided opposite to the mounting surface of the processing table 4 inside the vacuum container 1. The electrodes 8 are arranged not in the center of the etching chamber but in the left and right convex portions so as not to obstruct the flow of plasma. A high frequency power source 9 is connected to the electrode 8 and the mounting table 4, and a high frequency electric field is applied between the electrode 8 and the mounting table 4. By adjusting this high frequency electric field, the acceleration of the ions is adjusted by 2I.

As described above, in this embodiment, the acceleration of ions can be adjusted by applying a high-frequency electric field to the highly-densified plasma, and etching can be performed at high speed.

A plasma etching apparatus according to a fourth embodiment of the present invention is shown in FIG. Components that are the same as those in the embodiment shown in FIG. 1 are given the same reference numerals, and their explanations will be omitted. In this embodiment, no convex portion is provided on the lower side of the vacuum container 1, and the mounting table 4 is provided in the central etching chamber. In addition, the electrode 8 is connected to the vacuum container 1.
It is provided at a position opposite to the mounting surface of the mounting table 4 in the vacuum chamber 1, and near the base of the convex portion provided on the upper side of the vacuum container 1. This electrode 8 has a cylindrical shape along the side surface of the convex portion so as not to obstruct the flow of plasma. A high frequency power source 9 is connected to the electrode 8 and the mounting table 4, and a high frequency electric field is applied between the electrode 8 and the mounting table 4. By adjusting this high frequency electric field, the acceleration of ions can be adjusted.

As described above, in this embodiment, the acceleration of ions can be adjusted by applying a high-frequency electric field to the highly-densified plasma, and etching can be performed at high speed.

The present invention is not limited to the first embodiment, and various modifications are possible. For example, in the first embodiment, the confining magnetic field was generated and applied by two coils, but any configuration may be used as long as it applies a magnetic field that can confine the plasma in the area near the mounting table.

Furthermore, it goes without saying that what is etched is not limited to semiconductor wafers.

(Effects of the Invention) As described above, according to the present invention, plasma is generated using microwaves and a magnetic field, and the generated plasma is effectively used by confining it near the mounting table using a confining magnetic field, thereby causing damage to the object to be processed. It is possible to perform high-speed etching without giving any damage.

[Brief explanation of the drawing]

1 is a sectional view showing a plasma etching apparatus according to a first embodiment of the present invention, FIG. 2 is a sectional view showing a plasma etching apparatus according to a second embodiment of the invention, and FIG. 3 is a sectional view showing a plasma etching apparatus according to a second embodiment of the present invention. FIG. 4 is a sectional view showing a plasma etching apparatus according to a fourth embodiment of the present invention. 1... Vacuum vessel, 2... Quartz tube, 3... Waveguide,
4... Mounting table, 5... Wafer, 6A, 6B...
Coil, 8... Electrode, 9... High frequency power supply, 10...
・Magnetron. Applicant's agent Mr. Sato

Claims (1)

[Scope of Claims] 1. A vacuum container into which an etching gas is introduced; a mounting plate provided in the vacuum container and on which a workpiece is placed; A microwave applying means for applying a wave, and a magnetic field applying means for applying a confining magnetic field to the plasma near the mounting plate to confine the generated plasma in a region near the mounting plate. Characteristic plasma etching equipment. 2. In the plasma etching apparatus according to claim 1, a high-frequency electric field is applied between an electrode provided opposite to the workpiece mounting surface of the mounting plate and the mounting plate and the electrode. A plasma etching apparatus characterized by being equipped with a high frequency power source. 3. The plasma etching apparatus according to claim 1 or 2, wherein the magnetic field applying means includes a pair of coils whose surfaces are substantially perpendicular to the mounting plate. . 4. In the plasma etching apparatus according to claim 3, the magnetic field applying means causes current to flow in the same direction through the pair of coils, and applies a mirror magnetic field as the confining magnetic field. Plasma etching equipment. 5. In the plasma etching apparatus according to claim 3, the magnetic field applying means applies a cusp magnetic field as the confining magnetic field by passing current in opposite directions to the pair of coils. Plasma etching equipment. 6. The plasma etching apparatus according to claim 1 or 2, wherein the magnetic field applying means has a pair of coils whose surfaces are substantially parallel to the mounting plate. . 7. In the plasma etching apparatus as set forth in claim 6, the magnetic field applying means causes current to flow in the same direction through the pair of coils, and applies a mirror magnetic field as the confining magnetic field. Plasma etching equipment. 8. The plasma etching apparatus according to claim 6, wherein the magnetic field applying means applies a cusp magnetic field as the confining magnetic field by passing current in opposite directions to the pair of coils. Plasma etching equipment.