JP2990838B2 - Dry etching equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching apparatus used for manufacturing a semiconductor integrated circuit device, and more particularly to an ECR reactive ion etching apparatus using an electron cyclotron resonance method as an ion source.

[0002]

2. Description of the Related Art Conventional dry etching apparatuses include:
There is a so-called reactive ion etching apparatus in which an ion etchant is generated by high-frequency discharge and ions are vertically incident on the substrate by a negative bias applied to the substrate.

[0003] In addition, since ions can be generated even in a region where the pressure is about one order of magnitude smaller than that of a conventional high-frequency discharge, an ECR reactive which can reduce the microloading effect and improve the anisotropy can be achieved. Development of an etching apparatus is underway. E that has been studied
FIG. 4 shows a CR reactive etching apparatus. That is, an etching gas introduction pipe 2, a microwave introduction window 3, and a gas exhaust port 4 are attached to the vacuum vessel 1, and a substrate holder 5 for applying a high frequency is installed inside the vacuum vessel 1, and the substrate holder 5 is provided separately. A substrate transferred in a vacuum from a vacuum chamber (not shown) using a transfer mechanism (not shown) is fixed by a substrate clamp 13, and a magnetic field is applied to the outside. There is a coil 6. When using the vacuum container 1 with a turbo pump from the gas exhaust port 4
After evacuating the inside to about 10 ⁻⁵ Torr, an etching gas is introduced, and the pressure is maintained at about 1 × 10 ⁻³ Torr,
The magnetic field coil 6 is energized, and microwaves are introduced to generate plasma at a position facing the substrate.
At this time, 2.45 GHz for a magnetic field of 875 Gauss
, A high density plasma is generated by electron cyclotron resonance. Further, a high frequency is applied to the substrate holder 5 via the capacitor 7 to generate a negative bias of about 50 to 200 volts on the substrate 10, and positively charged etching ions are vertically incident on the substrate 10 to perform anisotropic etching. Achieved.

[0004]

In a conventional ECR etching apparatus, SF ₄ or SF _{6 is used} as an etching gas.
When a silicon nitride film or a polysilicon film is etched using such a fluoride gas, there is a problem that the etching rate in the peripheral portion of the substrate is 20% or more higher than that in the central portion. The reason for this is that the ion etchant is attracted to the negative bias of the substrate and is perpendicularly incident on the substrate, whereas the radical neutral etchant, which is electrically neutral, flows according to the gas flow without being affected by the magnetic field. This is probably because radical etching easily acts particularly on the periphery of the substrate. Therefore, it is considered that the etching rate in the peripheral portion becomes higher than that in the central portion of the substrate.

An object of the present invention is to provide a dry etching apparatus which solves the above problems.

[0006]

In order to achieve the above object, in a dry etching apparatus according to the present invention, an ion source using an electron cyclotron resonance method applying a magnetic field and a microwave is connected to a high frequency through a capacitor. An ECR reactive ion etching apparatus having a substrate holder for applying a voltage to the substrate, wherein the ion source and the substrate holder are disposed to face each other, and a side surface portion is formed on an outer peripheral portion of the substrate holder. A shield tube having a structure that is closed and has an open tube end and extends to a lower portion of the ion source is provided.

[0007]

The etching of the substrate is performed mainly by an ion etchant so as to improve the in-plane uniformity of the etching rate.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a first embodiment of the present invention. In the figure, 1 is a vacuum vessel, 2 is a gas inlet, 3 is a microwave introduction window, 4 is a gas outlet, 5
Is a substrate holder, 6 is a magnetic field coil, 7 is a capacitor, 1
0 is a substrate, 11 is a microwave introduction tube, 13 is a substrate clamp, and 14 is a high frequency power supply. The present embodiment has a structure in which a cylindrical quartz tube 8 as a shielding tube whose both ends are open is arranged between the ion source 12 and the substrate holder 5. That is, as shown in FIGS. 2A and 2B, the substrate holder 5 receives the substrate 10 transported at a position away from the quartz tube 8 and fixes it using the substrate clamp 13. The substrate holder 5 moves to the end of the quartz tube 8 while the substrate 10 is fixed, and is brought into close contact therewith. Therefore, at this time, the outer periphery and the back surface of the substrate 10 are hermetically sealed, and the direction of the ion generation source 12 is open. When etching is performed, the etching ions generated by the ion generating source 12 are attracted to the negative bias of the substrate 10 and are perpendicularly incident on the substrate and participate in the etching of the substrate surface. Most of the air is exhausted through the outer periphery of the quartz tube 8. Some etching radicals diffuse to reach the substrate, but reach the entire surface of the substrate uniformly, so that in-plane uniformity of etching does not occur. In the present invention, of course, another material other than the quartz tube, such as alumina ceramic, fluororesin, or alumite-treated aluminum, may be used.

(Embodiment 2) FIG. 3 is a sectional view showing Embodiment 2 of the present invention. The present embodiment is characterized in that the substrate clamp 9 is integrated with a quartz tube as a shielding tube. Also in this case, there is no influence of the radical etchant, and the etching of the substrate is mainly performed by the ion etchant. Therefore, the etching with good in-plane uniformity of the etching rate can be performed.

[0011]

As described above, the present invention has a structure in which the etching gas is not directly blown onto the substrate in accordance with the flow of the exhaust gas. Since there is no etching, the etching becomes uniform in the substrate surface, the etching can be controlled precisely, and a fine dimension in the vertical direction of the processed shape can be realized. In addition, since etching in the horizontal direction caused by the radical etchant can be reduced, etching with improved anisotropy can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a substrate holder according to the first embodiment.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

FIG. 4 is a sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Gas introduction port 3 Microwave introduction port 4 Gas exhaust port 5 Substrate holder 6 Magnetic field coil 7 Capacitor 8 Quartz tube 9 Quartz tube with substrate clamp 10 Substrate 11 Microwave waveguide 12 Ion source 13 Substrate clamp 14 High frequency power supply

Claims (1)

(57) [Claims] 1. An ECR reactive ion etching apparatus having an ion source using an electron cyclotron resonance method for applying a magnetic field and a microwave, and a substrate holder for applying a high frequency via a capacitor,
The ion source and the substrate holder are arranged to face each other, and a side portion is closed, and a tube end is opened at an outer peripheral portion on the substrate holder, and extends to a lower portion of the ion source. A dry etching apparatus characterized in that a shielding tube having a structured structure is provided.