JPH065722A - Manufacture of semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To enhance the reliability of the ohmic contact of a contact hole or a through hole in a multilayer interconnection. CONSTITUTION:A contact hole 17 which has been made in a layer insulating film is sputtered and etched in a mixed gas of an inert gas and a reactive gas; an adhesion substance which has been produced on the surface of a lower- layer aluminum interconnection 13 is removed. After that, an aluminum film is deposited by a sputtering operation without being exposed to the outside air; it is patterned. An upper-layer aluminum interconnection 19 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor integrated circuit device, and more particularly to a method for forming electrode wiring.

[0002]

2. Description of the Related Art In the manufacture of large-scale semiconductor integrated circuits (LSIs), a multi-layer wiring structure is often used because of the demand for high density and high speed.

First, after forming an opening (contact hole) for electrical connection in a part of an insulating film provided on a diffusion layer of a semiconductor substrate, an electrode and a wiring film are formed. Next, a first layer wiring and an interlayer insulating film are formed, and an opening (through hole) for electrical connection is formed in a part thereof, and then a second layer wiring film is formed. Hereinafter, an interlayer insulating film and a wiring metal film are alternately formed as needed to form a multilayer wiring structure. As the wiring metal film, an aluminum film, an aluminum alloy film, or a laminate of these and a titanium nitride film, a titanium tungsten film, or the like is mainly used, and a silicon oxide film, a silicon nitride film, or the like is used as the interlayer insulating film. .

Generally, in order to improve ohmic contact between both wiring films when forming an interlayer insulating film on the nth wiring and opening a through hole and then forming an n + 1th wiring metal film. Is used. In the through hole opening step, the interlayer insulating film is usually etched and opened using the photoresist film as a mask, and then the photoresist film is removed by a dry or wet peeling process. afterwards,
Oxide on the surface of the n-th wiring metal film in the through hole by sputter etching (formed by the reaction between the metal film and oxygen in the atmosphere), or the reaction product attached to the through hole during the through hole opening process. This is a method of forming the (n + 1) th wiring metal film by sputtering in the same vacuum after removing (those which were attached in the through hole etching step and could not be removed in the subsequent photoresist removing step) and the like. Here, sputter etching is usually 1
It is carried out by introducing an inert gas such as argon into a chamber evacuated to 0 ^-7 to 10 ^-8 Torr and performing high frequency discharge under a pressure of 10 ^-2 to 10 ^-3 Torr.

When a titanium nitride film or a titanium tungsten film is used as a barrier metal for the diffusion layer and the first wiring metal film, these metals are formed only on the contact part or on the entire surface of the substrate. Also, if the first wiring metal film is to be formed after being exposed to the atmosphere once,
After removing the oxide on the surface of the barrier metal by the same sputter etching, the first wiring metal film is formed by sputtering in the same vacuum to improve the ohmic contact.

[0006]

However, in the above-described conventional method for manufacturing a semiconductor integrated circuit device, even if the etching conditions for opening the contact holes or through holes and the sputter etching conditions before sputtering are optimized, There is a problem that the ohmic contact becomes unstable at the connection part of, or in some cases, the ohmic contact cannot be made at all.

Here, the ohmic contact becomes unstable because the molecules of the insulating film dissociated from the surface of the insulating film on the substrate surface or the side wall of the contact hole or the through hole during sputter etching are the barrier metal or If redeposited on the wiring metal film, or if the insulating film contains oxygen or contains moisture due to moisture absorption, the dissociated oxygen or water will be recombined with the barrier metal at the contact part or the wiring metal film at the through hole. Form oxides,
It is presumed that the upper layer metal film and the lower layer metal film to be connected are partially discontinuous at the connection interface.

Furthermore, stress migration or electromigration occurs at the interface portion due to temperature history, stress, or energization in the subsequent process, and the upper metal film and the lower metal film at the connection portion become completely discontinuous and disconnection occurs. It is thought to lead to.

[0009]

In the semiconductor integrated circuit device of the present invention, an insulating film is formed on a surface including a diffusion layer or wiring provided on a semiconductor substrate and selectively etched to form a surface of the diffusion layer or wiring. Forming an opening exposing the
Removing the deposits on the surface of the diffusion layer or the wiring by sputter etching the surface including the opening with a mixed gas of an inert gas and a reactive gas, without exposing the opening to the atmosphere. Subsequently, the method includes a step of depositing a metal film by sputtering, and a step of selectively etching the metal film to form an electrode wiring that is electrically connected to the diffusion layer or the wiring.

[0010]

1 (a) to 1 (d) are sectional views of a semiconductor chip in the order of steps for explaining a first embodiment of the present invention.

First, as shown in FIG. 1A, a silicon oxide film 1 formed by thermally oxidizing the surface of a silicon substrate 11.
A first-layer aluminum wiring 13 is selectively provided on the second layer 2, a low-temperature silicon oxide film 14 is formed on the surface including the aluminum wiring 13 by plasma enhanced chemical vapor deposition, and then a solution containing a silicon compound is applied. Then, heat treatment is performed to form a silica film 15, which is then etched back to be flattened, and a low temperature silicon oxide film 16 is formed again thereon to form an interlayer insulating film. Here, a low temperature silicon oxynitride film or a low temperature silicon nitride film may be used instead of the low temperature silicon oxide films 14 and 16.

Next, as shown in FIG. 1B, through holes 17 are formed in the interlayer insulating film by photolithography.
To open. Here, the cup-shaped through hole 17 is formed by combining isotropic etching and anisotropic etching.
At this time, the surface of the aluminum wiring 13 reacts with oxygen in the atmosphere to form an aluminum oxide 18.
The anisotropic etching (reactive ion etching) at the time of opening the through hole 17 needs to be performed under the condition that the reaction product (for example, fluorinated polymer) between the photoresist film and the etching gas is small. This reaction product is almost completely removed in the photoresist film peeling process by the dry and wet processes.

Next, as shown in FIG. 1C, an inert gas such as argon and a reactive gas such as SF ₆ are mixed in a ratio of about 10: 1 before sputtering the second wiring metal film. Into the etching chamber, a high frequency discharge is performed under a pressure of several mTorr to perform sputter etching. Thus, the aluminum oxide 18 in the through hole 17 is removed, and at the same time, the silicon oxide etched from the surface of the interlayer insulating film or the sidewall of the through hole and redeposited on the aluminum wiring 13 in the through hole 17 or the interlayer insulating film is removed. It is also possible to remove redeposits such as aluminum oxide newly formed by recombining dissociated oxygen and water. The sputter etching may be a two-step etching in which only an inert gas is initially performed and a reactive gas is introduced before the etching is completed to perform a mixed gas.

Next, as shown in FIG. 1D, an aluminum film is deposited by sputtering and selectively etched to form a second-layer aluminum wiring 19. Here, sputter etching and sputtering are continuously performed without exposing the substrate to the atmosphere, but as shown in FIG. 3, the etching chamber 31 and the sputtering chamber 32 are completely separated, and the sputtering chamber 32 contains a reactive gas. Make sure there is no effect of. That is, the etching chamber 31 and the sputtering chamber 32 are
Separated by an intermediate chamber 32 with an independent vacuum pump,
The gate balgs 33 connecting the chambers should not be opened at the same time. The substrate after the sputter etching is transferred from the etching chamber 31 to the intermediate chamber 34, and after the intermediate chamber is sufficiently evacuated, it may be transferred to the sputtering chamber 32. After that, the aluminum wiring 19 is formed through a photolithography process.

In this way, it becomes possible to completely remove redeposits such as aluminum oxide and silicon oxide which are inevitably formed on the aluminum wiring 13 in the through hole 17 during sputter etching. A stable ohmic contact in the hole 17 can be obtained.

In the case of a multi-layered wiring of three or more layers, formation of an interlayer insulating film, opening of a through hole, a series of sputter etching, wiring metal film sputtering, and wiring formation may be similarly repeated. Further, the wiring metal film may be not only a single layer wiring such as an aluminum film or an aluminum alloy film but also a laminated wiring such as an aluminum / titanium nitride / titanium film.

2 (a) to 2 (d) are sectional views of the semiconductor chip in the order of steps for explaining the second embodiment of the present invention.

First, as shown in FIG. 2A, a diffusion layer 21 is provided on a silicon substrate 11, and a silicon oxide film 12 is formed on the surface including the diffusion layer 21. Next, silicon oxide film 1
2, a contact hole 22 reaching the diffusion layer 21 is selectively formed.

Next, as shown in FIG. 2B, a platinum film is deposited on the surface including the contact holes 22 and reacted with silicon by a heat treatment to form a platinum silicide film 23 on the surface of the diffusion layer, which is not yet formed. The reaction platinum film is etched away.

Next, as shown in FIG. 2C, a titanium tungsten film 24 is deposited on the surface of the contact hole 22 including the platinum silicide film 23 by sputtering. Here, before sputtering, sputter etching is performed in the same manner as in the first embodiment to remove the oxide layer on the platinum silicide film 23 and at the same time from the surface of the silicon oxide film 12 and the side wall of the contact hole 22. Adhesive substances such as silicon oxide that are etched and redeposited on the platinum silicide film 23 are also removed. Next, the titanium tungsten film 24 is patterned by the photolithography technique.

Next, as shown in FIG. 2D, sputter etching is performed in the same manner as in the first embodiment to remove the oxide layer on the titanium-tungsten film 24 and at the same time.
The deposits such as silicon oxide that are etched from the surface of the silicon oxide film 12 and redeposited on the titanium tungsten film 24 are also removed. Next, an aluminum film is successively deposited on the surface including the contact holes 22 by sputtering without exposure to the outside air and patterned to form the aluminum wiring 13.

In this way, it becomes possible to completely remove redeposits such as silicon oxide which are inevitably formed on the barrier metal of the contact hole during sputter etching, and as a result, stable ohmic contact in the contact hole can be achieved. You can get contacts.

[0023]

As described above, according to the present invention, the sputter etching before the sputtering for forming the electrode film or the wiring film is performed in the mixed gas of the inert gas and the reactive gas, so that the contact hole and the through hole can be formed. It is possible to almost completely eliminate the influence of redeposited matter due to sputter etching, which is a problem in making ohmic contact. As a result, the ohmic contact in the contact hole or the through hole is stable and good, and at the same time, it is possible to provide the multilayer wiring having high resistance to stress migration and electromigration at the metal film interface of the contact hole or the through hole. Has the effect of improving.

[Brief description of drawings]

1A to 1D are cross-sectional views showing a process sequence for explaining a first embodiment of the present invention.

2A to 2D are sectional views showing a process sequence for explaining a second embodiment of the present invention.

FIG. 3 is a block diagram showing an example of a sputtering apparatus used in the present invention.

[Explanation of symbols]

 11 Silicon Substrate 12 Silicon Oxide Film 13,19 Aluminum Wiring 14,16 Low Temperature Silicon Oxide Film 15 Silica Film 17 Through Hole 18 Aluminum Oxide 21 Diffusion Layer 22 Contact Hole 23 Platinum Silicide Film 24 Titanium Tungsten Film 31 Etching Chamber 32 Sputtering Chamber 33 Gate valve 34 Intermediate chamber

Claims (1)

[Claims] 1. A step of forming an insulating film on a surface including a diffusion layer or a wiring provided on a semiconductor substrate and selectively etching to form an opening for exposing the surface of the diffusion layer or the wiring, and the opening. A step of sputter-etching the surface including a portion with a mixed gas of an inert gas and a reactive gas to remove deposits on the diffusion layer of the opening or on the surface of the wiring, and continuously sputtering without exposing the opening to the atmosphere. And a step of selectively depositing a metal film to form an electrode wiring that is electrically connected to the diffusion layer or the wiring. Method.