KR19980013737A - Tungsten etching method - Google Patents

Abstract

The subject innovation is tungsten and according to an etching method for etching a tungsten, using the insulating layer and, further, a mixed etching gas of SF ₆ and HBr to form a photoresist pattern in a predetermined area on the tungsten layer formed sequentially on the substrate Etching the layer, and removing the photoresist formed on the etched substrate.

Description

Tungsten etching method

FIG. 1 is a view for explaining a conventional tungsten etching method,

1 (a) to 1 (c) are process drawings for explaining a conventional tungsten etching method.

FIG. 2 is a view for explaining a tungsten etching method of the present invention,

2 (a) to 2 (c) are process drawings for explaining the tungsten etching method of the present invention.

Description of the Related Art [0002]

10, 20. Semiconductor substrate

11, 11 ', 21, 21'

12, 12 ', 12, 22, 22', 22. Tungsten layer

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a tungsten (WOLFRAM) etching method and, more particularly, to a method of etching a tungsten layer, which is a metal layer deposited on a substrate, Tungsten etching method.

FIG. 1 is a view for explaining a conventional tungsten etching method. FIG. 1 (a) to FIG. 1 (c) are process diagrams for explaining a conventional tungsten etching method step by step, .

As a conventional etching gas used for etching a tungsten layer, which is a metal layer deposited on a substrate, SF ₆ is used, and a conventional tungsten layer etching method using SF ₆ etching gas will be described below.

First, in the conventional metal layer etching method, a photoresist (PHOTORESIST) is formed on an insulating layer 11 sequentially formed on a substrate 10 and a tungsten (W) layer 12 as a metal layer, And the pattern is etched with a mask (MASK).

As shown in FIG. 1 (b) and FIG. 1 (c), the tungsten layer 12 'is etched using the SF ₆ gas while maintaining the process temperature at -30 °.

In this case, during the etching process in the state SF ₅ ⁺ SF ₆ gas plasma (PLASMA), SF ₄ ^2+, SF ₃ ^{3+, =} F, ⁼ F ^2, being here a ⁼ F ^3, F ⁼ here, F ^{2 =} , And F ^{3 =} groups react with tungsten to form WF _x .

Thus, as shown in FIG. 1 (c), the etching process proceeds to the top of the tungsten layer 12 and the insulating layer 11 'while the WF _x is formed. After the tungsten layer etching process is completed, Is completely removed to complete the process.

However, since the SF ₆ gas reacts on the side of the tungsten profile in view of the characteristics of the gas, the side surface is etched, and the profile is poor.

Therefore, the resistivity of the metal line is large because the etching profile of the tungsten layer is not good after the etching.

In addition, since the etching process is performed at -30 ° C., there is a problem that the additional equipment of the cooling unit for lowering the temperature is separately required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a tungsten etching method having superior lateral profile by forming a protective film on a tungsten layer in consideration of lateral etching of a tungsten layer.

Accordingly, the present invention provides, by using the mixed gas of SF ₆ and HBr gas to the tungsten layer formed on the substrate, the WBr _X formed by W and the reaction acts as a protective film on the side surface of the tungsten profile SF ₆ gas to the tungsten etching Thereby obtaining an excellent lateral profile after the etching process.

FIG. 2 is a view for explaining process steps of a tungsten etching method according to the present invention, and the present invention will be described with reference to the accompanying drawings.

Referring to FIGS. 2 (a), 2 (b) and 2 (c), a method of etching a tungsten (W) layer using an etching gas according to the present invention will be described.

2 (a), an insulating layer 21 sequentially formed on a substrate 20 and a predetermined region on the tungsten layer 22 are coated with a photoresist and patterned with a mask to pattern the etching region do.

Then, as in FIGS. 2B and 2C, the tungsten layer 22 'is etched using a mixed etching gas of SF ₆ and HBr.

In this case, SF ₆ gas during the etching process is SF ₅ ⁺ in a plasma ^{_{state, SF 4 2+, SF 3 3+}} , F =, F 2 =, and where a ^{3 =} F, where F ^=, F ^{= 2,} F ^{3 =} group are formed in the WF _X reacts with tungsten, and HBr gas and forms a WBr _X reacts with tungsten, such WBr _X is formed on the side of the W-profile, to the action of the protective film.

That is, HBr gas interferes with lateral etching of SF ₆ gas.

Therefore, the WBr _X protective film is formed on the side surface of the tungsten layer, and the etching process proceeds to the top of the tungsten layer 22 and the insulating layer 21 'due to the WF _X, as shown in FIG. 2 (c) ) After the etching, the photoresist is removed to complete the process.

Here, the temperature of the electrode placed on the wafer using SF ₆ / HBr gas proceeds at a room temperature (20 ° C) or higher. Further, the mixed etching gas of SF ₆ gas and HBr gas is mixed at a ratio of 1: 1 to 2: 1.

That is, while using a tungsten etching gas of SF _6, HBr gas of the present invention, the F group W the reaction excited by tungsten during layer etching, the plasma source and the tungsten layer is etched, but made also etched in its sides, HBr gas is the WBr _X formed by the reaction of tungsten and the action of the protective film on the side surface of the tungsten profiles.

Thus, the HBr gas interferes with the lateral etching of the SF ₆ gas so as to obtain a good profile after etching.

The conventional tungsten (W) etching gas is not only poor in side profile, but also requires that the electrode, which is placed on the wafer using conventional SF ₆ , should be processed at a temperature of -3O < However, by using the mixed gas of SF ₆ gas and HBr gas as the tungsten (W) etching gas of the present invention, excellent side profile can be obtained after etch, and the resistance of the metal line can be lowered.

In addition, since the process can be performed at room temperature, no additional cooling equipment is required, and the production cost is reduced.

Claims (3)

In an etching method for etching tungsten, A) forming an insulating layer sequentially formed on a substrate, forming a photoresist pattern in a predetermined region on the tungsten layer, B) etching the tungsten layer using a mixed etch gas of SF ₆ and HBr, C) removing the remnant photoresist on the etched substrate. A tungsten etching method is used. The method according to claim 1, Wherein the protective film is formed on the side of the WBr _X formed by the reaction of HBr and tungsten in the mixed etching gas in the step b). The method according to claim 1, Wherein the mixing ratio of the SF ₆ gas and the HBr gas in the step b) is 1: 1 to 2: 1.