JPH05109666A - Etching system - Google Patents

Abstract

PURPOSE:To perform the substrate processing step in high reliability capable of making electrons wind around a magnetic field, producing even plasma on the substrate to be processed and causing no damage at all by generating the magnetic field almost perpendicular to the first platelike electrode filling the role of an anode. CONSTITUTION:A substrate 2 to be processed is fixed to the first electrode 3 as a cathode having an electrostatic chuck while the first electrode 3 is arranged beneath a pressure reduced vessel to be electrically connected to a high-frequency power supply 4. Besides, the second electrode 5 as an anode is arranged in the pressure reduced vessel to be opposed to the first electrode 3 assuming the space of the vessel between the two electrodes 3 and 5 to be an etching region 6. A magnetic means 18 is arranged outside the pressure reduced vessel corresponding to the substrate to be processed. At this time, even plasma can be procuded to the substrate 2 by winding the electrons around the magnetic field perpendicular to the second electrode 5 due to the Lorentz force. Resultantly, no damage will be caused to the substrate 2 to be processed thereby enabling both characteristics and yield to be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an etching apparatus using magnetron discharge.

[0002]

2. Description of the Related Art In addition to etching for reducing the loading effect including the micro loading effect in response to submicron and high aspect ratio of semiconductor integrated circuits, especially memory devices, pattern conversion without using additive gas. There is a need for an etching means that produces a vertical shape with a small difference.

To satisfy such requirements, 4 Pa
A plasma source capable of generating high-density plasma in a low pressure region below (Pascal) is required. As this plasma source, a magnetron discharge is used, which causes cyclotron motion in electrons due to electric fields and magnetic fields that are orthogonal to each other to efficiently collide molecules and atoms, thereby promoting ionization.

An etching device utilizing magnetron discharge which fulfills such a function will be described with reference to FIG. That is, in the decompression container 1 that functions as a chamber for performing the etching process, the substrate 2 to be processed, which is a semiconductor substrate, is placed on the cathode electrode 3 having an electrostatic chuck. The first electrode 3, which functions as a cathode, is installed at the bottom of the decompression container 1 as is apparent in FIG. 1, which is electrically connected to the high frequency power supply 4.

On the other hand, the second electrode 5 which functions as an anode
Is placed in the decompression container 1 so as to occupy a positional relationship facing the first electrode 3, an etching region is provided between the two, and a gas nozzle 6 is installed below the etching region. A gas or fluid that reacts dynamically to form a reaction product having a high vapor pressure is introduced to enable etching, for example, anisotropic etching.

A cooling pipe 7 into which a cooling medium can flow is formed in the second electrode 5 to play a role of removing the harmful effects of etching products deposited on the second electrode 5. Magnetic means 8
As for, the magnets 9 having different polarities are arranged alternately and are attached eccentrically from the center of the decompression container 1, and a magnet rotation motor 10 for rotating the magnetic means 8 is installed on the top surface thereof. In order to maintain the atmosphere in the decompression container 1 from a vacuum state to a constant pressure state such as a decompression state, a turbo molecular pump 11
Is installed in the decompression container 1 via the buffer 12 to form an etching device.

[0007]

When the closed loop magnetic field as shown in FIG. 2 is used as the shape of the magnetic field for generating the magnetron discharge, the plasma is unevenly distributed in the portion where the horizontal magnetic field is strong, so that the substrate to be processed is installed. The plasma distribution becomes non-uniform near the first electrode. To solve this, a method of rotating the magnetic means or the substrate to be processed is adopted.

FIG. 2 shows a state in which the high frequency power source 4 is applied to the substrate 2 to be processed and the plasma A is generated at a position adjacent to the magnetic means 8.

However, in this method, the uniformity of plasma as an average value for a certain period of time is improved, but the nonuniformity of plasma at the moment does not change, and as a result, on the first electrode on which the substrate to be processed is placed. As a result, the high frequency current density at each point becomes different, resulting in damage. this is,
A problem such as deterioration of the most important gate oxide film of a moss type semiconductor device formed on a semiconductor substrate as a substrate to be processed occurs.

In order to eliminate such a drawback of the closed loop magnetic field, there is known a method of installing the horseshoe-shaped magnet 11 shown in FIGS. 3 and 4, and FIG. 3 is a side view and FIG. It is a top view.

As can be seen from both these figures, the uniformity of the horizontal magnetic field distribution on the first electrode can be improved, but since the magnetic field is not in a closed loop, as is apparent from the top view of FIG.
Since the electrons escape from the point A toward the point B, the plasma density at the point B becomes higher than that at the point A, and the plasma becomes nonuniform. As a result, although it is an improvement over the closed loop magnetic field, the problem of damage is not essentially solved.

The present invention has been made under such circumstances, and an object of the present invention is to provide a new etching device.

[0013]

A reduced pressure container, a substrate to be processed placed in the reduced pressure container, plate-shaped first and second electrodes arranged to face the substrate to be processed, and the substrate to be processed main A magnetic means installed outside the decompression container corresponding to the substrate to be processed so as to apply a magnetic field perpendicular to the surface, and an electric field almost parallel to the magnetic force lines generated from the magnetic means are generated to discharge near the electrode. And a means for introducing a fluid that chemically reacts with the substrate to be processed to generate a reaction product having a high vapor pressure, and a means for adjusting the pressure of the decompression container. Etching equipment

[0014]

In the present invention, a magnetic field that is almost perpendicular to the plate-shaped first electrode that functions as a cathode is created, so that the electrons act on the plate-shaped first electrode by the Lorentz force as shown in FIG. Then, a uniform magnetic field can be generated on the substrate to be processed by winding the magnetic field in a vertical direction, and the occurrence of damage can be eliminated, and a highly reliable substrate to be processed, for example, a semiconductor wafer can be processed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described with reference to FIGS. 5 and 6. The former is a diagram showing the concept of the present invention, and the latter is an outline of an etching apparatus by a sectional view. Regarding the numbers attached to both figures, the same parts as those in the conventional technology are the same.

As described above, in FIG. 5, for example, a semiconductor wafer, that is, a substrate to be processed 2 is provided in a chamber or a decompression container 1 of an etching apparatus for performing an etching process, and a cathode electrode 3 (hereinafter referred to as a first electrode) equipped with an electrostatic chuck. Fixed). As shown in FIG. 6, the first electrode 3 is installed below the decompression container 1 and electrically connected to the high frequency power supply 4.

On the other hand, the second electrode 5, which is an anode corresponding to the cathode in order to form an electric field indispensable for plasma generation, is arranged in the decompression container 1 so as to occupy a positional relationship facing the first electrode 3. Thus, the space of the decompression container 1 between the two is set as the etching region 6. A gas nozzle 7 is installed below the gas nozzle 7 to introduce a gas or fluid that chemically reacts with the substrate 2 to be processed to generate a reaction product having a high vapor pressure, thereby enabling anisotropic etching. Second electrode 5
The cooling pipe 7 into which the cooling medium can flow is formed to play a role of eliminating the adverse effects caused by the temperature rise.

As shown in FIG. 6, a magnetic means 8 is provided outside the decompression container 1 corresponding to the substrate 2 to be processed. For this reason, as in the conventional case, the eccentric magnetic means 8 and the motor or magnet for rotating the eccentric magnetic means 8 are not required above the second electrode 5, resulting in a compact etching apparatus.

It should be noted that the magnetic means 8 may be installed not only in a single unit as shown in FIG. 6 but also in a plurality of units (see FIG. 5).

In order to maintain a constant pressure state such as a reduced pressure state from a vacuum state in the atmosphere inside the decompression container 1, a turbo molecular pump 11 is installed in the decompression container 1 via a buffer 12 to form an etching device. Further, the decompression container 1 is provided with a peephole 13 through which the inside can be observed, and a fluid inlet and an outlet are installed in the first electrode 3 to cool the substrate 2 to be processed, which is not shown, and etching is performed. Complete the device.

[0021]

As described above, in the etching apparatus according to the present invention, the magnetic means 8 is installed outside the decompression container 1 corresponding to the plate-shaped substrate 2 to be processed, so that electrons are applied to the second electrode by Lorentz force. On the other hand, since it is wound around a perpendicular magnetic field, it is possible to generate uniform plasma on the substrate 2 to be processed. As a result, the substrate 2 to be processed is not damaged, which is extremely good for a MOS type memory device, for example. That is, a semiconductor substrate having an active region or a passive region formed thereon is coated with a selective oxide film having a thickness of about 10,000 angstroms, and a part thereof is removed to expose the active region or the passive region to a thickness of about 150 to 300. A process has been used in which an angstrom gate oxide layer is provided and a conductive metal layer is deposited thereon.

No damage occurs during the processing of the oxide film or the gate oxide film, the characteristics of the memory device are improved, and the yield is improved, which is extremely effective in practice.

[Brief description of drawings]

FIG. 1 is a sectional view showing an outline of a conventional etching apparatus.

FIG. 2 is a diagram showing an operation of a magnetron type etching apparatus.

3 is a side view of the operation when a horseshoe-shaped magnet is used to improve the drawbacks of the etching apparatus of FIG.

FIG. 4 is a top view of the operation of the etching apparatus when using a horseshoe-shaped magnet.

FIG. 5 is a diagram showing an outline of the operation of the etching apparatus according to the present invention.

FIG. 6 is a sectional view showing a main part of an etching apparatus according to the present invention.

[Explanation of symbols]

 1: Decompression container, 2: Plate-shaped substrate to be processed, 3: First electrode, 4: High frequency power supply, 5: Second electrode, 8: Magnetic means.

Claims (2)

[Claims] 1. A decompression container, a substrate to be processed placed in the decompression container, plate-shaped first and second electrodes arranged to face the substrate to be processed, and a main surface of the substrate to be processed. Magnetic means installed outside the decompression container corresponding to the substrate to be processed so as to apply a perpendicular magnetic field, and means for generating an electric field near the electrodes by generating an electric field almost parallel to the magnetic lines of force generated from the magnetic means. An etching apparatus comprising: a means for introducing a fluid that chemically reacts with the substrate to be processed to generate a reaction product having a high vapor pressure; and a means for adjusting the pressure of the decompression container. 2. An etching apparatus, wherein a magnetic field direction applied between a plate-shaped first electrode on which a substrate to be processed is mounted and a second electrode facing the plate-shaped electrode is perpendicular to both electrodes.