JPS63245926A - Manufacture of semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To prevent the corrosion and change of properties of a wiring metal by removing an insulating film or a metallic thin-film applied onto a semiconductor substrate through reactive ion etching and conducting the high-frequency sputtering etching of an inert gas without exposure into atmospheric air. CONSTITUTION:A photoresist 14 is formed to a wiring section on the laminate of an silicon substrate 11, an silicon oxide film 12 and an aluminum film 13. When the film 13 is removed selectively through a reactive ion etching RIE method, using the resist 14 as a mask, a reaction product 16 adheres onto a side face. The substrate 11 is not exposed to atmospheric air, transferred into a sputtering etching chamber separate from a reaction chamber in which RIE is performed, and etched through the high-frequency sputtering of an inert gas in environment in which an PIE gas and the reaction product are not mixed. Consequently, the product 16 adhering on a section to be etched is gotten rid of. Accordingly, the corrosion and change of properties of an aluminum wiring can be obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor integrated circuit, and particularly to microfabrication by dry etching.

[Conventional technology]

In large-scale integrated circuits, dry etching is widely used as a microfabrication method for patterning metal wiring films, opening holes in insulating films, and the like. Among them, reduction in side etch,
Anisotropic etching technology using reactive ion etching (hereinafter referred to as RIE) has been introduced from the viewpoint of machinability of mask pattern dimensions.

[Problem that the invention seeks to solve]

During etching by RIE, a reaction product between a substance released from the photoresist and the etching gas plasma adheres to the side surface of the portion to be etched. This reaction product is
The reaction products remain even after RIE is completed, and once the semiconductor substrate is exposed to the atmosphere, the reaction products oxidize and become firmly attached to the etched area, making it difficult to remove in the subsequent resist removal process.

Reaction products that are not removed during the resist removal step cause problems in subsequent steps. For example, in the case of patterning a wiring metal film, wiring corrosion may occur, and in the case of through-hole opening in an insulating film between the eyebrows, the wiring metal film deposited on the through-hole portion may be altered by heat treatment in the post-process. There is a problem like that.

The object of the present invention is to provide a manufacturing method that eliminates defects caused by the above-mentioned reaction products.

[Means for solving problems]

In the present invention, after a reactive ion etching process for selectively removing an insulating film or metal thin film deposited on a semiconductor substrate using a photoresist pattern as a mask, the ion etching process is performed without exposing the semiconductor substrate to the atmosphere. With the reactive gas removed, organic reaction products produced in the etched area in the ion etching step are removed by high frequency sputtering of an inert gas.

[Effect]

If the semiconductor substrate is exposed to the atmosphere immediately after RIE, the reaction products will be oxidized, and their adhesion to the insulating film and metal thin film will become stronger, making it impossible to remove them later. In the present invention, it is not exposed to the atmosphere and can be easily removed by high frequency sputtering using an inert gas. However, it is necessary to carry out the process in a state where no ion etching reaction gas remains.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

As a first example, regarding patterning of a wiring metal film, a case of a first layer of aluminum wiring will be described.

FIG. 1 is a sectional view showing the steps in order. 11 is a silicon substrate, and 12 is a silicon oxide film formed by, for example, thermal oxidation. An aluminum film 13 is deposited thereon by sputtering.

Next, photoresist is spin-coated, irradiated with ultraviolet light through a mask for wiring formation, and developed, leaving 14 feet of photoresist remaining on the portion to be wired (FIG. 1(a)). Next, RIE is first performed using this photoresist 14 as a mask. Etching is performed by high frequency discharge using carbon tetrachloride (CCL), boron trichloride (BCQs), or the like as a reaction gas under a pressure of about 10 mTorr to 100 m'l'orr. Photoresist 1 on the side of the wiring part
A product (chlorinated polymer) 16 resulting from the reaction between the substance released from 4 and the etching gas adheres, protects the side surfaces of the wiring portion, and anisotropic etching is performed. FIG. 1(b) shows a state in which RIE has been completed, with reaction products 16 still attached to the side surfaces of the first layer aluminum wiring 15.

Next, without exposing the silicon substrate 11 to the atmosphere,
Etching (hereinafter referred to as sputter etching) by high frequency discharge sputtering is performed using an inert gas such as argon under a pressure of about 10 mTOrr. As a result, the reaction product 16 is removed as shown in FIG. 1(C). After that, the photoresist 14 was removed, as shown in FIG. 1(d).
As shown in FIG. 1, the first layer aluminum wiring 15 is formed.

As a second embodiment, a case where a through hole is formed in an interlayer insulating film will be described with reference to FIGS. 1 and 2. The interlayer insulating film has a two-layer structure of low-temperature silicon oxide and low-temperature silicon nitride. FIG. 2 (Ll is after forming the first layer aluminum wiring 15 by the method of the first embodiment,
A silicon nitride film 21. is grown by chemical vapor deposition. Silicon oxide layer 22 is grown at low temperature in order, and photoresist 23 is placed on top of it.
The state in which the through hole 24' has been closed is shown.

As a mask for the photoresist 23, first apply silicon oxide M.
After etching 22 isotropically by wet etching, it was etched using nitride silicon 7 and 21k RIE.

Then perform anisotropic etching. The reaction gas is carbon tetrafluoride (CF4) or cumulative carbon difluoride (CHsFz).
) etc., from 10m'l'orr to 100mTorr
Do this under moderate pressure. FIG. 2(b) shows the entire state after RIE, in which a reaction product (fluorinated polymer) 25 is attached to the side surface of the through hole 24.

After this, a pressure of 10 mTor is applied without exposure to the atmosphere.
Perform sputter etching in an inert gas of approximately
The reaction product is removed as shown in Figure (c). Similarly, the photoresist 23 is removed and a through hole for connection to the first layer aluminum wiring 15 is formed in the interlayer insulating film.

Note that in this example, the interlayer insulating film has a two-layer structure,
By changing the etching method to be isotropic or anisotropic, a through hole 24 with a wide upper diameter is formed to ensure a secure connection with the second layer aluminum wiring.

In both the first and second embodiments, sputter etching is performed continuously after RIE without exposing the semiconductor substrate to the atmosphere. This is because the reaction products become oxidized when exposed to the atmosphere, and their removal becomes difficult over time.

FIG. 3 shows an example of an apparatus capable of continuously performing the above-mentioned RIE and high-frequency sputtering without taking out the semiconductor substrate into the atmosphere.

The etching device has a load lock chamber 31. The transfer chamber consists of an intermediate chamber, a reaction chamber (RIE chamber), and a sputter etch chamber, and the arrows indicate the direction (order) in which the wafers are sent.

The RI Ei34 and the sputter etch chamber are isolated between intermediate chambers, and each chamber has an independent exhaust system.
Further, the respective chambers are communicated by opening and closing the pulp I, and by closing the pulp I, the semiconductor substrates are transferred and delivered. By operating Pulp I, it is possible to prevent the reaction chamber A and the sputter etch chamber A from being connected to the intermediate chamber O at the same time, which completely prevents reaction gases from entering the sputter etch chamber and prevents RIE during sputter etching. No redeposition of reaction products occurs.

〔Effect of the invention〕

As explained above, in the present invention, after an insulating film or metal thin film deposited on a semiconductor substrate is selectively removed by reactive ion etching (RIE), it is not exposed to the atmosphere and is continuously etched. By performing high frequency sputter etching in an active gas, reaction products adhering to the portion to be etched by RIE are removed. Therefore, due to exposure to the atmosphere as in conventional methods, reaction products oxidize and cannot be removed in subsequent processes, making it impossible to completely prevent accidents such as corrosion or deterioration of wiring metal. can.

Note that since sputter etching is performed in plasma of an inert gas such as argon, resist molecules and gas molecules do not react. Even if the resist molecules released into the gas re-adhere to the etched area, they are easily removed in a subsequent resist process.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing embodiments of the present invention, and FIG. 3 is a view showing an example of an etching apparatus for carrying out the present invention. 11... Silicon substrate, 12... Silicon oxide film,
13... Aluminum film, 14... Photoresist,
15...First layer aluminum wiring, ]6...Reaction product, 21...Silicon nitride film, n...Silicon oxide film, B...Photoresist, Q...Through hole, 5...・Reaction products,...
Intermediate chamber, ah°°°reaction chamber 1a...sputter etch chamber, audience...pulp. Procedural master's letter (spontaneous)

Claims (1)

[Claims] In a reactive ion etching process for selectively removing an insulating film or metal thin film deposited on a semiconductor substrate using a photoresist pattern as a mask, after the process is completed, the semiconductor substrate is exposed to the atmosphere. A semiconductor integrated circuit characterized in that organic reaction products generated in the etched portion in the ion etching step are removed by high frequency sputtering of an inert gas in a state where the ion etching reaction gas is removed. Production method.