JPS61235575A - Dry etching device - Google Patents

Abstract

PURPOSE:To increase the selection ratio of SiO2 with respect to Si by providing a control device to an introducing pipe for introducing an etching gas into a vacuum vessel and controlling the pressure and residence time of the etching gas in the vacuum vessel. CONSTITUTION:A material A to be treated, i.e., an Si substrate formed thereon with an SiO2 film, is imposed atop a lower electrode 4 and after the inside of the vacuum vessel 1 is evacuated to a vacuum by a vacuum evacuating device 9, the etching gas (CF4) is introduced through a gas introducing pipe 8 into the vessel. The etching gaseous pressure in the vessel 1 is maintained under a high pressure of 400Pa by a control device 11 in this stage and etching is executed by turning on an RF power source 7 to impress high-frequency electric power to the lower electrode 4, thereby generating plasma 12. The control device 11 controls the flow rate of the etching gas to that the residence time per unit of the etching gas in the vessel 1 is maintained for >=4sec. The selection ratio of SiO2 with respect to Si is thus remarkably increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a dry etching apparatus, and more particularly to a dry etching apparatus capable of increasing the selectivity of 5ho2 to a workpiece 81.

[Technical background of the invention and its problems]

Conventional RI EIG! In a (reactive ion etching device), a pair of parallel plate electrodes are arranged inside a vacuum container, and a gas inlet pipe for etching gas and a gas exhaust pipe connected to a vacuum exhaust device are connected to the vacuum container. The object to be processed is fixed to one of the electrodes. After evacuating the inside of the vacuum container by vacuum evacuation, etching gas is introduced into the vacuum container through the gas introduction tube, and high frequency power is applied to the electrodes to generate plasma. The material to be processed is etched by ionizing or radicalizing the material.

However, in the above method, when only CF4 is used as the etching gas, the etching selectivity ratio (Si02/Si
) becomes about 1, and when etching is performed,
This method has the disadvantage that even the Si substrate of the object to be processed is etched, resulting in a significant decrease in etching reliability.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a dry etching apparatus capable of increasing the selectivity ratio of S t 02 to Si.

(Summary of the Invention) In order to achieve the above object, a dry etching apparatus according to the present invention includes a pair of parallel plate electrodes arranged in a vacuum container, a workpiece to be processed is fixed to one of the parallel plate electrodes, and a dry etching apparatus according to the present invention is provided. In a dry etching device that etches the object to be processed by applying high frequency power to the electrodes while introducing an etching gas into the container, a part of the inlet tube into which the etching gas is introduced is placed in the vacuum container. A control device is provided to control the etching gas pressure and the flow rate of the etching gas, and this control device controls the etching gas pressure in the container to 400 Pa and the residence time of the etching gas to 4 seconds or more. It is characterized by:

(Embodiments of the Invention) Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows an embodiment in which the present invention is applied to an RIE apparatus, in which an upper electrode 2 is disposed on the inner upper surface of a vacuum vessel 1, and an insulating member is provided on the inner lower surface. 3
A lower electrode 4 is disposed through the vacuum vessel 1.
The upper electrode 2 portion is recessed downward so that the distance between each of the electrodes 2 and 4 is 10jIII or less. Further, cold 2Jl water pipes 5, 5 are electrically connected inside each of the electrodes 2, 4, and an RF 11f source 7 is connected to the lower electrode 4 via a matching circuit 6.

Further, a gas introduction pipe 8 for feeding etching gas from a gas introduction device (not shown) and a gas exhaust pipe 10 connected to a vacuum evacuation device 9 are connected to the vacuum container 1. In this case, the etching gas pressure and etching gas flow rate inside the vacuum container 1 are
A control device 11 is provided.

In this embodiment, a workpiece A consisting of a SiO2 film formed on a Si substrate is placed on the upper surface of the lower electrode 4, and after evacuating the inside of the vacuum container 1 using a vacuum evacuation bag [9], CF as an etching gas is introduced into the chamber by a gas introduction pipe 8.
4 will be introduced. Then, the etching gas pressure in the vacuum chamber 1 is maintained at a high pressure of about 400 Pa by the control device @ 11, and the RFt source 7 is turned on and high frequency power is applied to the lower electrode 4 to generate plasma 11. This is for etching the processed material A. Then, cooling water is circulated through the cooling water pipe 5.5 to cool each electrode 2.4 and the object to be processed.

Further, in this embodiment, the flow of etching gas is controlled by the control device 11 so that the residence time per unit of etching gas in the vacuum container 1 is 4 seconds or more, and the residence time is increased in this way. As a result, the etching rate of Si decreases as shown in FIG.
It can be seen that the selectivity ratio for Also,
If the residence time is less than 4 seconds, the etching rate of 3i will be high and no improvement in selectivity can be expected.

〔Effect of the invention〕

As described above, in the dry etching apparatus according to the present invention, the pressure of the etching gas is set to 400 Pa by the control device, and the residence time of the etching gas is set to 4 seconds or more. Since the etching rate of 5i02 is reduced, the selectivity of 5i02 to Si can be significantly increased, and the uniformity is also high.

[Brief explanation of drawings]

1 and 2 each show an embodiment of the present invention, in which FIG. 1 shows a schematic configuration of the RIE apparatus, and FIG. 2 shows a diagram showing the relationship between gas residence time and etching rate. It is. DESCRIPTION OF SYMBOLS 1... Vacuum container, 2... Upper electrode, 3... Insulating member, 4... Lower electrode, 5... Cooling water pipe, 6... Matching circuit, 7... RF power supply, 8 ... Gas introduction pipe, 9 ... Vacuum exhaust device, 10 ... Gas discharge pipe, 11
...Control device, 12...Plasma.

Claims (1)

[Claims] A pair of parallel plate electrodes are arranged in a vacuum container, a workpiece is fixed to one of the parallel plate electrodes, and high frequency power is applied to the electrodes while introducing an etching gas into the vacuum container. In a dry etching apparatus for etching a workpiece, a control device for controlling the etching gas pressure and the flow rate of the etching gas in the vacuum container is interposed in the middle of the introduction pipe for introducing the etching gas. A dry etching apparatus characterized in that the etching gas pressure in the vacuum container is controlled to 400 Pa and the residence time of the etching gas to 4 seconds or more.