JPH0774153A - Etching system - Google Patents

Abstract

(57) [Summary] [Object] To provide a small-sized etching system capable of efficiently removing products of a substrate in an ion-assisted etching process. In an etching system for etching a substrate 2 placed in an etching chamber 1 with ions 4 from an ion source 5 and an etchant gas from an etchant gas supply source, the etchant gas is removed from the etching chamber 1.
By supplying the gas from the throat nozzle 7 provided on one side of the substrate and evacuating the diffuser 8 provided on the other side of the etching chamber 1 with the substrate 2 interposed therebetween,
The etchant gas is characterized by passing through the surface of the substrate 2 at supersonic speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate etching system, and more particularly to a substrate arranged in an etching chamber.
The present invention relates to an etching system that performs etching with ions from an ion source and etchant gas from an etchant gas supply source.

[0002]

2. Description of the Related Art In recent years, semiconductors have been actively developed and manufactured in accordance with an increase in demand for LSIs (Large Scale Integrated Circuits) and the like. An etching process is one of the development and manufacturing processes of semiconductors and is indispensable for forming circuit patterns and the like.

Etching includes wet etching and dry etching. Since wet etching is isotropic etching, it is not suitable for etching a fine pattern of a thick film or opening of a narrow contact, but dry etching is anisotropic etching and is suitable for etching a fine pattern of an LSI or the like. .

An ion assisted etching system is one of the dry etching systems. In this method, a substrate placed in an etching chamber is etched with ions from an ion source and etchant gas from an etchant gas supply source.

[0005]

In the ion-assisted etching system described above, reaction products are generated on the substrate and affect the film quality of the substrate. Therefore, it is necessary to remove the reaction products. To remove the reaction products, it is necessary to increase the flow rate of the etchant gas.

However, in order to increase the flow rate of the etchant gas, it is necessary to increase the injection amount of the etchant gas and increase the evacuation speed of the vacuum pump, which increases the size of the source of the etchant gas and the vacuum pump. As a result, the etching system becomes large.

Therefore, an object of the present invention is to solve the above problems and to provide a small etching system capable of efficiently removing the product of the substrate in the ion assisted etching process.

[0008]

In order to achieve the above object, the present invention provides an etching system for etching a substrate placed in an etching chamber with ions from an ion source and an etchant gas from an etchant gas supply source. In, the etchant gas is supplied from a throat nozzle provided on one side of the etching chamber, and is evacuated from a diffuser provided on the other side of the etching chamber across the substrate, so that the etchant gas is discharged from the substrate. It is designed to pass over the surface at supersonic speed.

[0009]

According to the above construction, the throat nozzle has a constricted structure in which the cross section perpendicular to the longitudinal direction is once narrowed as it goes downstream and then widened. Therefore, the etchant gas supplied from the etchant gas supply source to the throat nozzle is accelerated to supersonic speed from a wide portion to a narrow portion inside the throat nozzle by Bernoulli's law, and is discharged from the throat nozzle. Since the etchant gas passes through the surface of the substrate at a supersonic speed, reaction products on the substrate are blown off and collected by the diffuser. A boundary between the etchant gas region and the vacuum region, that is, a free boundary surface is formed between the throat nozzle and the diffuser to maintain the vacuum in the etching chamber. Further, since the etchant gas collected by the diffuser is decelerated to a subsonic speed and has a high density, it can be easily exhausted by a small vacuum pump.

[0010]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic view of an embodiment of an etching apparatus to which the etching system of the present invention is applied.

In the figure, 1 is an etching chamber,
In the center of the etching chamber 1, the substrate 2 to be etched is
It is arranged on a holding means (not shown), and this holding means is rotated by a rotating means (for example, a motor) 3.

An ion source 5 for supplying ions 4 to the substrate 2 is provided above the etching chamber 1. At the bottom of the etching chamber 1, the etching chamber 1 is vacuumed (about 10 ⁻⁴ torr).
A vacuum pump 6 is provided to keep the temperature at r).

One side of etching chamber 1 (left side in the figure)
Is provided with a throat nozzle 7, and an inlet of the throat nozzle 7 is connected to an etchant gas supply source (not shown) for supplying a high temperature etchant gas to the etching chamber 1. The throat nozzle 7 has a constricted structure in which a cross section perpendicular to the longitudinal direction is once narrowed toward the downstream side (right side in the drawing) and then widened. The outlet of the throat nozzle 7 has, for example, an elliptical shape, and its width (length in the direction perpendicular to the paper surface) is larger than the maximum width when the substrate 2 is rotated.

The other side of the etching chamber 1 (right side in the figure)
Is provided with a diffuser 8 with the substrate 2 interposed therebetween. The shape of the inlet of the diffuser 8 is, for example, an elliptical shape, and its width (length in the direction perpendicular to the paper surface) is larger than the maximum width when the substrate 2 is rotated. A cross section of the diffuser 8 perpendicular to the longitudinal direction becomes narrower toward the downstream side, and is connected to a vacuum exhaust system.

Next, the operation of the embodiment will be described.

Ions 4 from the ion source 5 are transferred to the etching chamber 1
And the etching chamber 1 is evacuated by the vacuum pump 6.

The etchant gas is supplied from the etchant gas supply source to the throat nozzle 7 and is evacuated through the diffuser 8. Since the throat nozzle 7 has a constricted structure, the etchant gas is accelerated to a supersonic speed (for example, about Mach 2) from a wide portion to a narrow portion inside the throat nozzle 7 according to Bernoulli's law. . Since the high-speed, high-density etchant gas emitted at supersonic velocity passes through the surface of the substrate 2, the reaction products generated on the substrate 2 by the ions and the etchant gas are blown off and exhausted through the diffuser 8. A boundary between the etchant gas region and the vacuum region, that is, a free boundary surface 9 is formed between the throat nozzle 7 and the diffuser 8, and a shock wave 10 is formed in the diffuser 8.
Is occurring. Therefore, the vacuum in the etching chamber 1 is maintained (the pressure around the substrate is about 10 ⁻³ torr).
Therefore, the ion source 5 operates in the low vacuum region and supplies the ions 4 into the flow in the region inside the free boundary surface 9 and the shock wave 10.

The etchant gas in the diffuser 8 is decelerated to a subsonic speed and has a high density, and can be easily exhausted by a small vacuum pump (normal rotary pump). Further, since the substrate 2 is rotated by the motor 3, the etchant gas will flow evenly on the substrate 2 and the non-uniformity due to the difference between the upstream and the downstream is eliminated.

Here, the free boundary surface 9 is originally known in the field of aeronautical engineering such as rocket engine and jet engine, but in the present embodiment, the free boundary surface 9 is formed in the etching chamber 1. And then use it.

As described above, according to this embodiment, the etchant gas is supplied from the throat nozzle provided on one side of the etching chamber, and the diffuser provided on the other side of the etching chamber with the substrate interposed therebetween is vacuumed. Since the etchant gas is allowed to pass through the surface of the substrate at a supersonic speed by being exhausted, it is possible to realize a small etching system capable of efficiently removing the reaction product of the substrate in the ion assisted etching process.

[0022]

In summary, according to the present invention, the following excellent effects are exhibited.

The etchant gas is supplied from a throat nozzle provided on one side of the etching chamber, and
By evacuating the diffuser provided on the other side of the etching chamber across the substrate, the etchant gas was allowed to pass through the surface of the substrate at supersonic speed. It is possible to realize a small etching system that can be efficiently removed.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of an etching apparatus to which an etching system of the present invention is applied.

[Explanation of symbols]

 1 Etching chamber 2 Base plate 5 Ion source 7 Throat nozzle 8 Diffuser

Claims (1)

[Claims] 1. In an etching system for etching a substrate placed in an etching chamber with ions from an ion source and an etchant gas from an etchant gas supply source, the etchant gas is supplied to one side of the etching chamber. The etchant gas is supplied from a throat nozzle provided and is evacuated from a diffuser provided on the other side of the etching chamber across the substrate so that the etchant gas passes through the surface of the substrate at a supersonic velocity. An etching system characterized by the above.