JPH034025Y2 - - Google Patents

Description

[Detailed Description of the Invention] In the manufacturing process of semiconductor devices, there is an etching process for removing unnecessary portions of various thin films. In this process, with the miniaturization of patterns and to prevent contamination, a shift has been made from wet etching to dry etching.

The present invention relates to a so-called plasma etching apparatus which utilizes activation by discharge of a reactive gas in dry etching.

First, the conventional technology will be explained. Currently, for plasma etching of aluminum alloys, polycrystalline silicon, high melting point metals, their silicides, etc., a parallel plate type etching apparatus, whose structural cross-sectional view is shown in FIG. 1A, is mainly used because of its fine processing properties.
In this device, the thin film is etched with a compound gas containing a strongly adsorbing gas such as chlorine, and when a compound with a low vapor pressure is generated as a reaction product, the loading effect causes the sample wafer, that is, the substrate 3 to be etched. The etching speed at the center becomes slower. As a means of suppressing such a phenomenon, reactive gas 7 is injected from near the center of the substrate. In this case, a high-density plasma 12 is generated at the reactive gas injection port 6, and a solid substance 11 containing the elements of the reactive gas is generated near the injection port 6 as shown in FIG.
If this device is used for a long time, the solid deposits 11 will fall onto the substrate 3 and act as an etching mask, which will be a major hindrance to subsequent steps. In Fig. 1, 1 is an upper flat electrode, 2 is a lower flat electrode, 4 is a chamber (reduced pressure vessel) of the etching device, and 5 is a gas inlet with a gas inlet 6 provided below surrounding the upper electrode 1. 8 is a conductance valve for regulating gas flow, 10 is an exhaust, 9 is a high frequency power source, and 12 is a high density plasma.

The present invention was developed to eliminate the above-mentioned drawbacks, and will be explained with reference to FIG. 2 in which the present invention is implemented.
FIG. 2A is a sectional view of the vicinity of the gas inlet 6, showing a state in which the jig of the present invention, that is, the porous jig 13 made of fluororesin whose top view is shown in FIG. 2B, is attached to the gas inlet 6. By installing this jig 13, generation of high-density plasma at the gas injection port and its vicinity is suppressed, so that solid matter 11 does not adhere to the gas injection port and its vicinity as shown in FIG. 1B. The product yield is greatly improved. Moreover, if there are no deposits, there will be no falling objects, and the number of times the chamber 4 must be cleaned will be much less, reducing the non-operating time of the apparatus, and thus significantly increasing the production output.

Next, the jig of the present invention will be explained in more detail with reference to FIG. This jig 13 is made of a fluororesin, such as Teflon, and is a stopper provided with a large number of small-diameter passages (hereinafter referred to as pores) 14 passing through the upper and lower surfaces, and is fitted so as to cover the entire opening of the gas inlet 6. Install it so that it fits in. Since the reactive gas 7 flows through these pores 14, the conductance becomes small, but by providing a large number of pores, the conductance of the jig portion can be increased. Since this jig 13 is an electrically good insulator, application of a high electric field to the pores can be avoided, and no plasma is generated in this part. The material of the jig is not limited to fluororesin (Teflon), and may be any material such as Teflon or alumina that does not easily react with passing gas and has high electrical insulation. The pores 14 may have a diameter of about 0.5 to 2 mm, and the reaction gas 7 is injected between the etching electrodes 1 and 2 through the many pores 14, and the substrate 3 is plasma etched by the plasma generated below the jig. will be held.

In addition to the above-described etching using plasma, the use of plasma in thin film generation devices has an extremely wide range of effectiveness because high energy can be obtained at low temperatures. The present invention has wide application when it is desired not to generate high-density plasma near the gas injection port when various gases are injected into various processing chambers.

[Brief explanation of drawings]

Figure 1 shows a schematic diagram A of the structure of a conventional parallel plate plasma etching device, B shows an example of the state of solid deposits near the reaction gas injection port, and Figure 2 shows the jig of the present invention attached to the reaction gas injection port. Figure A and top view of the jig B
It is. DESCRIPTION OF SYMBOLS 1... Upper electrode, 2 is the lower electrode, 3... Sample wafer, 4... Chamber, 5... Outer enclosure of the reaction gas passage surrounding 1, 6... Reaction gas injection port, 7... Reaction gas, 9 ...High frequency power supply, 10...Exhaust, 11
...Solid deposits, 12...High density plasma, 13
... Jig, 14... Many small diameter passages (pores).

Claims (1)

[Claim for Utility Model Registration] A reactive gas injection port provided in a gas inlet surrounding the upper flat electrode for injecting the reactive gas toward the vicinity of the center of the wafer to be processed placed on the lower flat electrode. Each of the inlets is provided with a number of distributed pores that fit over the entire opening of the reaction gas inlet and penetrate from one side to the other, making it difficult to react with the reaction gas;
and a plasma etching apparatus configured such that a plug made of a material with high electrical insulation is inserted and fitted so that the reaction gas is injected only through the plurality of pores.