JPS62183529A - Dry etching apparatus - Google Patents

Abstract

PURPOSE:To degrade organic polymers by an ultraviolet ray and avoid accumulation of a deposited film by a method wherein, while a specimen is being subjected to etching and treatment with film forming gas, the ultraviolet rays is applied to dust and a deposited film composed of organic polymers which cause defects adhering to the inner wall of a chamber. CONSTITUTION:An ultraviolet ray is applied to an undesirable part other than a specimen to be etched, for instance to an organic polymer film accumulated as a deposited film on the inner wall of a vacuum chamber while a specimen is being subjected to a treatment. As the polymer film which is being deposited during etching is degraded by photoexcitation, the practical deposition speed can be made to be zero or very little. In other words, monomer molecules which are diffused from a plasma onto the inner wall of the vacuum chamber and contain carbon and so forth form deposition of organic polymer by polymerizing reaction on the surface of the inner wall during etching but, at the same time, the polymer is degraded by the ultraviolet ray applied from the outside so that practically the accumulation of the deposited film on the inner wall surface can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dry etching apparatus used for manufacturing semiconductor integrated circuits.

[Conventional technology]

In recent years, methods have been developed to realize highly integrated devices. To realize this device structure.

First, the monocrystalline silicon must be vertically etched.

The reactive ion etching (RIE) method is known as a method for vertically etching a silicon substrate.
Even if RIE is performed using only halogen gas such as C or SFG, a perfectly vertical shape cannot be obtained. For example, Fig. 4(a)
As shown in the figure, when a 5in2 mask (2) is formed on a silicon substrate (1) as shown in the figure and etching is performed along this mask (2), the central portion of the groove (19) is bulged and the light is incident obliquely.

Recently, a method has been developed in which deposition is performed at the same time as etching, and etching is performed while forming a polymer film (10) on the side wall as shown in FIG. 4(b), thereby suppressing the effect of obliquely incident ions and etching vertically. is proposed.

[Problem that the invention seeks to solve]

However, this type of method has the following problems. That is, in order to cause deposition, it is necessary to mix carbon-containing gas with halogen gas and form a polymeric film on a sample such as a silicon substrate at the same time as etching, but this polymeric film is It adheres as a deposited film on the electrode surface and the inner surface of the vacuum container. When the deposited film adhering to the inner surface of the container or the like is peeled off, it becomes dust, which adheres to the device and causes a decrease in yield.

Furthermore, as etching is repeated, the deposited film that adheres to the inner surface of the vacuum container becomes thicker, and this deposited film may fly during plasma generation, causing abnormalities in etching. For this reason, it is necessary to periodically clean the inner surface of the container, which has the disadvantage of lowering the operating rate of the apparatus.

The present invention has been made in consideration of the above circumstances, and its purpose is to reduce the amount of deposited film adhering to the vacuum container, thereby reducing dust and improving device operating efficiency. An object of the present invention is to provide a dry etching device.

[Means for Solving the Problems] In order to achieve the above object, the present invention comprises a first electrode on which a sample is placed and a second electrode disposed opposite to this electrode. a vacuum container having a wall, a means for introducing gas for etching and film formation into the container, a vacuum container having the inside of the container, a means for applying a high frequency voltage between the electrodes, and the ultraviolet-transparent wall. and an ultraviolet light source located outside the dry etching apparatus.

[Effect]

With this structure, when processing a sample, ultraviolet light is irradiated onto an undesirable part other than the sample to be etched, such as an organic polymer film deposited on the inner wall of a vacuum chamber, and the etching process is performed by photoexcitation. The polymer film that is being deposited can be decomposed, and the actual deposition rate can be reduced to zero or extremely low.

That is, monomer molecules containing carbon and the like diffused from the plasma to the inner wall of the vacuum chamber during etching.

A polymerization reaction occurs on the inner wall surface, forming a deposit of organic polymers, but at the same time, it is decomposed by ultraviolet light irradiated from the outside, so the accumulation of the deposited film on the inner wall surface is effectively suppressed. It will be done.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram showing a dry etching apparatus according to this embodiment. This device consists of a chamber (■), a light source part 0 placed outside this chamber (2), a gas supply part (2) that supplies gas into the chamber (ω), a pump system (■) that exhausts the inside of the chamber (ω), and a power supply part). c).

First, the main parts of this embodiment, the chamber ■ and the light source part 0
I will explain about it. The chamber ■□ has a metal electrode (13) as a first electrode (cathode), a second electrode (29) placed opposite to this electrode (13), and both of these electrodes (13).
) and (29), its outer wall is formed by an ultraviolet-transparent quartz wall surface (11) held so as to be sandwiched between the quartz wall surface (11), a metal electrode (13), and a second
vacuum sealing rubber (1) between the electrodes (29).
2) provides insulation and maintains hermeticity inside the chamber. A water-cooled tube (14) is attached to the metal electrode (13).
are welded and the entire electrode (13) is water-cooled. Further, the metal electrode (13) is connected to the electrostatic force generation power supply unit that generates electrostatic force for holding a sample (15) such as a semiconductor substrate on which an IC pattern is formed.
and the plasma generation power supply unit ■. Furthermore, the light source unit 0 includes a low-pressure mercury lamp (16) and a concave mirror (16).
7). The low-pressure mercury lamp (16) is placed outside the quartz wall (11);
), the ultraviolet light is irradiated directly or reflected by a concave mirror (17) onto the inner wall surface of the chamber (2).

Next, other parts of FIG. 1, namely, the pump system (1), the gas supply section (3), and the power supply section), and (2) will be explained.

The pump system (2) includes a metal exhaust pipe (21) connected to the second electrode (29) of the chamber (2) via a vacuum sealing rubber (12'), and a main valve directly connected to this metal exhaust pipe (21). (22) and an oil rotary pump (24) that vacuums the inside of the chamber ω through this valve (22).
), an oil diffusion pump (23), and the gas supply section ■:
It consists of a mass flow controller (19) and a valve (18) that control the flow rate to the chamber ω, and a gas supply pipe (20) that supplies gas into the chamber ω through these.

In addition, the power supply section) and (2) are respectively a power supply section for generating electrostatic force consisting of a DC power supply (28) that supplies electrostatic force for fixing the sample (15) to the chamber ω via a coil (27), and a power supply section for generating electrostatic force in the chamber. This is a plasma generation power supply section consisting of a matching circuit (25) and a high frequency power supply (26) for generating plasma.

Next, the effects of the above-described embodiment will be described. First, apply 20ta of CBrF3 gas to the quartz wall (11).
During the Qh rinse, gas was supplied from the gas supply section (2), and the valve (22) was adjusted so that the pressure inside the chamber was 0.08 Torr. Next, a high frequency power of 300 W was applied to the electrode (13) to generate plasma. And while plasma is being generated,
Ultraviolet light from a 500W low-pressure mercury lamp (16) is applied to the chamber■
The wall surface (11) (here, quartz glass was used for monitoring the deposited film thickness) was irradiated. The thickness of the deposited film formed on this silica glass-7+ from CBrF in the plasma and monomer molecules (in this case, CF or CVX) generated by the collision of gas and electrons in the plasma is determined as a function of the plasma discharge time. This is shown in Figure 2.

From this, it can be seen that when the mercury lamp (16) is not turned on (indicated by 0 in the figure), about 50 people per minute accumulate as shown by straight line A, whereas when the mercury lamp (16) is turned on (indicated by 0 in the figure), about 50 people accumulate per minute. As shown by straight line B, it can be seen that the film deposition is negligibly small.

FIG. 3 is a diagram showing the change in the amount of dust generated with respect to the number of wafers processed when a wafer as a sample (15) is etched on a real seal. When the mercury lamp (16) is turned on (straight line C, indicated by . in the figure), the amount of dust generated is clearly lower than when it is not lit (straight line D; indicated by 0 in the figure). There is.

In the above embodiment, the quartz wall surface (11) was used, but instead a stainless steel chamber wall surface was used, and a quartz plate was placed inside the wall surface, so that the interior of the chamber was divided into two parts.
As a layered structure, a mercury lamp may be provided between them.

The light source is not limited to the above-mentioned low-pressure mercury lamp (16), and any ultraviolet light of 300 nm or less may be used, and the entire wall surface (11) does not need to be made of quartz, and is limited to quartz. It's not a thing. In short, the ultraviolet rays generated by the light source are irradiated directly or by reflection from a reflecting mirror such as a concave mirror (17) through an ultraviolet-transparent plate to the wall surface on which the deposited film is attached inside the chamber, thereby reducing the formation of the deposited film. Any configuration may be used.

Furthermore, the gas for etching and film formation need not be fixed by force, but may be fixed mechanically.

〔effect〕

As described above, according to the present invention, during etching and processing of a sample with a film-forming gas, ultraviolet light can be irradiated onto the deposited film made of organic polymers that may cause dust or defects adhering to the inner wall of the chamber. This allows the ultraviolet light to decompose organic polymers and prevent or extremely reduce adhesion of the deposited film.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a dry etching apparatus according to an embodiment of the present invention, FIGS. 2 and 3 are characteristic diagrams showing the effects of the present invention, and FIG. 4 is an explanation for explaining the above example. It is a diagram. 1... Chamber, 6... Light source section, 11...
Quartz wall surface, 12... Rubber for vacuum sealing, 13
...first metal electrode (cathode), 15...sample, 16...low-pressure mercury lamp, 1
7... Concave mirror, 29... Second electrode (anode). Agent Patent Attorney Noriyuki Ken Yudo Takehana Kikuo Ho'tt2 [minutes] Figure 2 U8-Shobiyo! Gisu Electric (Fig. 8) Fig. 4

Claims (1)

[Claims] A vacuum container including a first electrode on which a sample is placed and a second electrode placed opposite to this electrode and having at least an ultraviolet-transparent wall, and means for introducing gas for etching and film formation into the container. and means for evacuating said container;
A dry etching apparatus comprising means for applying a high frequency voltage between the electrodes and an ultraviolet light source disposed outside the ultraviolet transmitting wall.