JPS635528A - Reactive sputter etching device - Google Patents

Abstract

PURPOSE:To prevent the etching surface from being roughened as well as etching shape during etching process from deteriorating by a method wherein the surface receiving ion impulse out of the inner surface in contact with discharged plasma is covered with aluminaceramics material. CONSTITUTION:A target covering member 2 made of aluminaceramics is arranged on a target electrode 1 in a vacuum chamber 7 while an opposing plate 6 also made of aluminaceramics is arranged above the target covering member 2. Besides, a gas discharge pipe 4 made of aluminaceramics is annexed on the peripheral side of target covering member 2 while a high prequency power supply is connected to the target electrode 1. Etching specimens 3 containing single crystal or polycrysatlline silicon is closely arranged on the target covering member 2 made of aluminaceramics. Through these procedures, oxygen can be prevented from being produced from the electrode covering member 2 to be mixed with the element to be etched so that the surface of element to be etched may be prevented from being roughened by readhering etc. of oxgen as well as etching speed from decelarating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a parallel plate type dry etching apparatus.

BACKGROUND OF THE INVENTION Reactive sputter etching or reactive ion etching has a number of advantages over aqueous etching and is an established technique in the field of semiconductor manufacturing. It is known that this etching method improves the etching characteristics by combining a target electrode coating member and an etching introduction gas that are suitable for the material to be etched.

Conventionally, for reactive sputter etching of silicon materials, quartz (Si02> or surface alumina coating (Al2O2) of aluminum metal is used as the target electrode coating member, and CCβ3F, C(j) is used as the etching introduction gas.
! 4. CF4+02. SiF4. SF6+(1
2゜CCJ! 4+α2, etc. have been used. Here, active ions in the plasma generated by applying a high-frequency electric field are accelerated in the ion sheath zone near the surface of the cathode electrode and are perpendicularly incident on the sample to be etched.The sputtering effect due to physical ion bombardment and the chemical reaction generated in the discharge plasma are discussed. Etching progresses through a chemical reaction in which chemically active neutral molecules react on the surface of the material to be etched to produce volatile products.

[Problems to be Solved by the Invention] Recently, as semiconductor devices have become more densely integrated, the demand for highly accurate processing technology for fine patterns has been imposed on dry etching. The problems with reactive sputter etching are the deposition of products due to re-reaction with halogen compounds in the plasma, the occurrence of roughening of the surface of the material to be etched due to redeposition, and the reduction in processing accuracy caused by a decrease in the dry etching resistance of the resist mask. There are many problems that need to be resolved, including deterioration. These phenomena are caused by the use of quartz (S) in the electrode coating material.
i02) is used. The cause is thought to be the release of oxygen (02) from the quartz plate due to ion bombardment.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reactive sputter etching apparatus which prevents roughening of the etched surface and deterioration of the etched shape during etching caused by using a conventional quartz plate target electrode coating member.

[Means for Solving the Problems] The present invention provides a dry etching apparatus in which a material to be etched is disposed closely on an electrode, in which at least the surface exposed to ion bombardment of the inner surface of the apparatus facing the discharge plasma is made of alumina ceramic. This is a dry etching device characterized by being coated with a material.

[Example] Next, an embodiment according to the present invention will be described using the drawings.

FIG. 1 schematically shows a parallel plate type reactive sputter etching apparatus. In the apparatus according to the present invention, a target coating member 2 made of alumina ceramics is installed on a target electrode 1 in a vacuum chamber 7, and a counter plate 6 made of alumina ceramics is placed facing above the target coating member 2. This is what I did. Further, a gas blowing pipe 4 made of a ceramic material such as alumina is attached to the outer peripheral edge side of the target coating member 2, and a high frequency power source 5 is connected to the target electrode 1.

In the example, an etching sample 3 containing single crystal or polycrystalline silicon is placed closely on a target covering member 2 made of alumina ceramics. Next, using a mixed gas of sulfur hexafluoride and Freon-12 as the etching gas to be introduced, this is blown out from the gas blowing tube 4 made of alumina ceramic material and applied to the target electrode 1 by the high frequency power source 5 to generate it. Adjust plasma discharge interval. After the adjustment, plasma discharge is performed in the atmosphere of the mixed gas to etch the silicon to a predetermined thickness, and then the high frequency electric field is stopped and the sample 3 is taken out.

In the above embodiments, an etching apparatus having two disc-shaped electrodes has been described, but the present invention is also effective when applied to an etching apparatus having polyhedral electrodes or a reactive ion beam etching apparatus having an independent ion source. There are no particular restrictions on the discharge method or electrode shape.

The electrode coating material of the present invention has excellent spatter resistance and does not become a source of contamination, especially alumina ceramics, which are excellent among materials.Especially when the material to be etched is silicon, a mixed gas of sulfur hexafluoride and Freon-12 is used as the etching gas. The effect is noticeable when Conventionally, problems such as surface roughness and reduction in etching speed can be solved by quartz (Si0
2), since alumina ceramics do not release oxygen, the above-mentioned problems do not occur, the function of the resist mask can be maintained, and highly accurate etching can be performed.

FIG. 2 shows the etching characteristics comparing the alumina ceramic of the present invention and a conventional quartz coating.

The etching conditions were a gas mixture of sulfur hexafluoride and Freon-12 at a ratio of 10:1, and a pressure cuff of 5 Pa.

High frequency power dependence after etching for 30 minutes, O in the figure.
The mark indicates alumina ceramics, and the mark indicates quartz. In the comparative example shown in the figure, at 200W, a resist mask of 130A#++in has a selectivity of 12 with respect to the Si etching rate of 1600A/min in the case of alumina according to the present invention, and in the case of conventional quartz, a selectivity of 12 is obtained. The resist mask is 340A for the etching speed of 1200A/min.
/min, the selectivity is 3 times higher, indicating that the combination of alumina ceramics, sulfur hexafluoride, and Freon-12 mixed gas has an excellent effect.

Furthermore, FIG. 3 shows the etching characteristics depending on the pressure (Pa) dependence under the same conditions as described above, in which Q indicates the alumina ceramic coating according to the present invention, and . indicates the conventional quartz coating. Also in this figure, it is clear that the present invention is superior to the conventional one.

[Effects of the Invention] According to the present invention, by preventing the generation and contamination of oxygen from the electrode coating material, it is possible to prevent roughening of the surface of the material to be etched due to redeposition and a decrease in the etching rate, and also to prevent the material to be etched and the resist mask from becoming rough. Excellent effects such as high selectivity with materials can be obtained.

A particularly remarkable effect is silicon (S;
) and the resist mask, and when compared with etching under the same conditions using a conventional quartz electrode coating, a selectivity that is 3 times higher can be obtained, which is effective in obtaining a good etched shape. .

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a parallel plate type reactive sputter etching apparatus which is an embodiment of the present invention, Fig. 2 is a diagram of etching characteristics due to high frequency power dependence, and Fig. 3 is a diagram of etching characteristics due to pressure dependence. . 1...Target electrode 2...Target electrode covering member 3...Etching sample 4...Gas blow-off pipe 5
...High frequency power supply 6...Opposing plate 7...Vacuum chamber

Claims (1)

[Claims] (1) In a parallel plate type dry etching apparatus in which a substrate made of the material to be etched is placed closely on an electrode, at least the surface that receives ion bombardment of the inner surface of the apparatus facing the discharge plasma is coated with an alumina ceramic material. A reactive sputter etching device characterized by: