JPS59211249A - Wirings forming method - Google Patents

Abstract

PURPOSE:To prevent the operating speed of a semiconductor device of multilayer wiring structure by forming a high melting point metal layer contacted with the first wirings in a contacting hole, thereby reducing the contacting resistance between the first wirings and the second wirings. CONSTITUTION:An impurity region 2 is formed on the surface of a silicon substrate 1, the first insulating film 3 is formed, the first contacting hole 4 is opened, and the first aluminum wirings 5 are formed. The second insulating film 6 is formed, with a resist 7 as a mask the second contacting hole 8 is opened, and Mo layer 9 is formed. The resist 7 is removed, the layer 9 is allowed to remain only in the hole 8, and the second wirings 10 which are contacted with the layer 9 are formed. Even if the substrate is heated to improve the step coverage at the time of forming the second wirings, no aluminum oxidized film is formed on the surface of the first wirings, and the contacting resistance between the first wirings and the second wirings can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION A) Industrial Application Field The present invention provides an insulating film χ on a first wiring formed on a substrate and made of A4, and a contact hole formed in the insulating film. The present invention relates to a wiring formation method for forming a second wiring, which is appropriately connected to the first wiring, on this insulating film.

BACKGROUND ART In recent years, as semiconductor devices have become smaller and more integrated, interconnections formed on semiconductor substrates have also become more compact.

When forming such multilayer wiring on a semiconductor substrate,
Conventionally, a first wiring layer (Al) serving as a lower layer wiring is provided on a semiconductor substrate via a first insulating film, a second insulating film is formed on the substrate surface including the first wiring, and the first wiring is After appropriately forming a contact hole in the second insulating film on the wiring, a sputtering method is used on the second insulating film so that the contact hole is connected to the first wiring in a desired connection state. ◇ By the way, when forming such a second wiring, it is important to avoid the step part that exists at the difference between it and the first wiring. In order to improve the step coverage of the metal wiring, sputtering for forming the second wiring was performed while heating the entire board.

Therefore, when forming the second wiring, the first wiring formed by HL is also heated, and the surface portion of the first wiring exposed in the contact hole portion is oxidized. There was a risk that the contact resistance with the wiring would increase, leading to a decrease in the operating speed of the semiconductor device.

C) Purpose of the Invention The present invention has been made in view of the above points, and includes a first wiring serving as a lower layer wiring and an upper layer wiring.
purpose.

2) Structure of the Invention In the present invention, an insulating film is formed on a first wiring made of Al provided on a substrate, and a desired resist pattern 2 is provided on this insulating film. ! ? A contact hole exposing the upper surface of the first wiring is formed in the insulating film as a mask, and a high melting point metal layer is formed only in the contact hole by a lift-off technique using the resist 7. The second wiring in contact with the metal layer? The structure is designed to form a structure.

E) Embodiment FIGS. 1 to 8 are cross-sectional views showing the wiring forming method of the present invention in the order of steps, and the present invention will be explained in detail with reference to these figures. First, as shown in Figure 1, a thermal diffusion method, an ion implantation method, etc. are used on the surface of a semiconductor substrate of one conductivity type, such as a P-type silicon substrate (1), to form components of semiconductor elements such as resistors, diodes, and transistors. After providing the N-type impurity region (2), the entire surface of the substrate 111 is heated by thermal oxidation, CVO, etc.
A first insulating film (3) made of SiO2 is formed. Next, a first contact hole (4) is formed at a suitable location in the first insulating film (3) on the impurity region (2) (Fig. 2), and a sputtering method is used to form a first contact hole (4) through this contact hole (4). The first wiring (51vAl) in contact with the impurity region 12)
(Figure 6). Subsequently, using the CVD method, the entire surface of the substrate (1) including the first wiring (5) 1c Si
A second insulating film t6120 [J opening ~ 5000A thickness is formed (Fig. 4), and then the first wiring (5) is formed.
A resist mx with a pattern for opening a contact hole in the upper second insulating film 161Vci is formed,
Dry or wet etching is performed as a coruscist mask (7) to form a second contact hole (8) at a suitable location in the second insulating film (6) on the first wiring (5). figure). After drilling the second contact hole (8),
The above resist) i71F<Remaining state, deposit a high melting point metal such as MO to a thickness of about 1000A and Mo layer (9)
(Figure 6). For example, in the case of the subverting method, the deposition conditions at this time are atmospheric pressure 2×10 To
rr4i power is 5KW, and the substrate 11) is carried out without heating. Next, M was attached to the side surface of the second contact hole (8) using a nitric acid-based etchant.

At the same time as etching, the resist (7) is removed to form a Mo layer (
9) Leave it all intact (Figure 7). Next, the surface of the Mo layer (9) was cleaned with an HF-based etchant, and the entire substrate 11) was heated to about 600°C, and in good condition, Al was deposited on the entire surface of the substrate 11) using a sputtering method or the like. , this Alt is etched into a desired shape, and a second wiring U is formed in contact with the Mo layer (9) through the second contact hole (8).
α is formed to complete the multilayer wiring structure (FIG. 8). When forming such a second wiring layer 1, the entire substrate (1) is heated, but the first wiring layer (1) in the second contact hole (8) is heated.
5) is covered with the Mo layer (9), no oxide film of hl is formed on the upper surface of the first wiring (5). Moreover, Mo, which is a high melting point metal, is not oxidized at a temperature of about 600° C., and no oxide film is formed on the surface of the Mo layer (9).

(F) Effects of the Invention As described above, in the wiring forming method of the present invention, a contact hole is formed in the insulating film on the first wiring, and a high melting point metal layer that is in contact with the first wiring is provided in the contact hole. After
Since the @2 wiring in contact with the refractory metal layer inside the contact hole is formed on the insulating film, even if the substrate is heated to improve step coverage when forming the second wiring, the contact hole area will not be affected. The first wiring surface [Aj7 oxide film is not formed and the contact resistance between the first wiring and the second wiring can be reduced, and the operation of a semiconductor device using this multilayer wiring formation method is Prevents speed reduction. Furthermore, the present invention utilizes a lift-off technique using a resist to open a contact hole.
Since layers are formed, the process of forming wiring throughout the entire structure does not become complicated due to the formation of Mo dot shadows.

[Brief explanation of drawings]

1 to 8 are cross-sectional views showing the wiring forming method of the present invention in the order of steps, in which 111 is a semiconductor substrate, (3) (6)
(9) indicates an insulating film, +51ul indicates a wiring, and (9) indicates a Mo layer.

Claims (1)

[Claims] An insulating film is provided on the first wiring made of Al formed on the substrate 1, and a second wiring is connected to the first wiring as appropriate through a contact hole 2 formed in the insulating film. When forming on the film, A, 14 on the substrate
a step of forming a wiring of the first layer using w, a step of forming an insulating film covering the first wiring on the substrate, a step of forming a desired resist pattern on the insulating film, and forming the first wiring as the resist pattern. a step of opening a contact hole in the appropriate location of the insulating film on the wiring, a step of providing a high-melting point metal layer only in the contact hole using a resist-required lift-off technique that serves as a mask for opening the contact hole; A wiring forming method comprising the steps of: forming a second wiring on the insulating film in contact with the refractory metal layer in the contact hole while heating the entire surface of the substrate.