JPH05109709A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve the operation speed by forming a wiring layer composed of a first conducting film in a T-type. CONSTITUTION:Tungsten is deposited to be 5000Angstrom thick by a sputtering method; photo resist is spread; the photo resist is patterned by using a projection alignment method; the photo resist is used as a mask, and patterning is so performed that the wiring width is 1.5mum and the wiring becomes T-shaped. After that, dry etching is performed by using chlorine based etching gas like BCl2-Cl2, and the photo resist which has been used as the mask is eliminated by sulfuric acid peeling. Thus a tungsten wiring layer 4 is formed. Thereby a semiconductor device of high operation speed can be supplied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring structure for a semiconductor device.

[0002]

2. Description of the Related Art At present, three kinds of metals, such as diffusion layers, polysilicon, and aluminum, are mainly used as wiring materials for semiconductor integrated circuits (IC, LSI).

A semiconductor device using such a wiring material is shown in FIG. In FIG. 1, a diffusion layer 2 is formed on a semiconductor substrate 1 containing impurities of the first conductivity type by implanting the impurities of the second conductivity type by an ion implantation method using a photoresist as a mask and thermally diffusing the impurities. To do. Next, the photoresist is removed by stripping with sulfuric acid, tungsten is deposited by the CVD method, and the tungsten is patterned using the photoresist and dry-etched to form a tungsten wiring layer on the diffusion layer 2.

[0004]

However, in the semiconductor device having the above structure, when the element is to be miniaturized, it is necessary to reduce the width of the tungsten wiring layer 4. However, even if the width of the tungsten wiring layer 4 is reduced, the current flowing in the wiring does not change,
The current density in the wiring increases. If the current density in the wiring increases, the reliability of the device will deteriorate. See also FIG.
When the tungsten wiring layer 4 is on the diffusion layer 2 as described above, the operating speed of the device is reduced due to the capacitance between the tungsten wiring layer 4 and the diffusion layer 2.

In order to solve the above problems,
The cross-sectional area is increased by increasing the thickness of the wiring layer without changing the width of the tungsten wiring layer 4 to reduce the current density, and the tungsten wiring is formed on the diffusion layer 2 to reduce the interlayer capacitance. A method such as not forming the layer 4 is conceivable. However, in such a method, the contact area between the tungsten wiring 4 and the first insulating film layer 3 is the same,
Since the tungsten wiring layer 4 becomes thicker, it causes a defect such as sulfuric acid peeling for removing the photoresist after the wiring layer is etched, or a contact surface is peeled off in a cleaning process to collapse the wiring layer. There is a problem such as becoming. Even if the problem is solved, such a method is not suitable for selectively forming wiring positions from the viewpoint of device miniaturization.

Therefore, an object of the present invention is to speed up the operation speed by reducing the degree of integration of the device, the reliability of the wiring layer, and the interlayer capacitance.

[0007]

A semiconductor device having a wiring layer formed of a first insulating film formed on a semiconductor substrate and a first conductive film formed on the first insulating film,
A semiconductor device having a T-shaped wiring layer formed of a conductive film.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for forming a tungsten wiring layer according to the present invention will be described below with reference to the drawings.

FIG. 2 is a vertical side view of a tungsten wiring layer formed by applying the present invention. See also FIG.
FIGS. 3A to 3C are vertical cross-sectional side views showing a process of forming the tungsten wiring layer 4 in FIG. 2 into a T shape.

In the figures, 1 is a semiconductor substrate, 2 is a diffusion layer, 3 is a first insulating film, and 4 is a tungsten wiring layer.

Hereinafter, the embodiment shown in FIG. 2 will be described with reference to FIGS.
A detailed description will be given using (c).

As shown in FIG. 3A, a photoresist is coated on the impurity semiconductor substrate 1 of the first conductivity type, the photoresist is patterned by a projection exposure method, and then impurities of the second conductivity type are removed. Implantation is performed on the semiconductor substrate 1 by using an ion implantation method, and the semiconductor substrate is annealed in a nitrogen atmosphere at 1000 ° C. for 30 minutes to form a diffusion layer 2. Next, the photoresist is removed by stripping with sulfuric acid, and then a 4000 Å silicon oxide film is deposited by a CVD method to form a first insulating film layer 3.

After that, a photoresist is applied, and the photoresist is patterned by a projection exposure method. After that, the photoresist is used as a mask, and a fluorine-based etching gas such as CHF ₃ --C ₂ F ₆ is used to form a photoresist film having a width of 0. 5 μm, depth 2000 ∂ dry etching. Then, after removing the photoresist used for the mask by sulfuric acid stripping, FIG.
It shows in (b).

Next, as shown in FIG. 3C, 5000 Å of tungsten is deposited by a sputtering method, a photoresist is applied thereafter, and the photoresist is patterned by a projection exposure method. Then, the photoresist is used as a mask. Then, patterning is performed so that the wiring shape has a T shape with a wiring width of 1.5 μm. After that, dry etching is performed using a chlorine-based etching gas such as BCl ₂ —Cl ₂ ,
By removing the photoresist used as the mask by sulfuric acid peeling, the tungsten wiring layer 4 as shown in FIG. 2 is formed.

When the T-shaped tungsten wiring layer 4 is formed by the above steps, the conventional rectangular tungsten wiring width as shown in FIG.
Assuming that the thickness of the first insulating film layer is 5 μm and the thickness of the first insulating film layer is 2000 Å, the interlayer capacitance generated between the tungsten wiring layer 4 and the diffusion layer 2 is T
When it is formed in a letter shape, it is reduced to 2/3 of the conventional one. Further, by forming the tungsten wiring layer 4 into a T-shape, the cross-sectional area is increased from 7.5 μm ² to 8.5 μm ² , so that the same current density is obtained when the same current is applied to the tungsten wiring layer 4. Is reduced by 15/17 times.

In the present invention, the tungsten wiring layer 4 is also used.
However, since the tungsten wiring layer 4 is formed so as to be embedded in the first insulating film 3, the tungsten wiring layer 4 is removed from the first insulating film 3 in a step of removing sulfuric acid for cleaning the photoresist after etching and cleaning. It goes without saying that the contact surface with and peels off and falls.

Further, although the present invention describes the case where tungsten is used for the wiring layer, a high melting point metal compound such as Mo, W, or Ti is deposited on polysilicon wiring, Al wiring, or polysilicon to 900 °. The wiring may be silicided at a high temperature of about C to 1000 ° C.

In the present invention, the diffusion layer 2 in which the conductive film under the tungsten wiring layer 4 is formed on the semiconductor substrate has been described. However, in a multi-layer wiring type semiconductor device in which wiring is further present under the wiring 4. Widely applied.

[0019]

According to the method of forming the wiring layer made of the first conductive film of the present invention, the shape of the first conductive film is T.
By forming it in the shape of a letter, without changing the width of the first conductive film,
By reducing the current density of the wiring layer formed of the first conductive film and reducing the interlayer capacitance without impairing the reliability of the wiring layer, a semiconductor device having a high operating speed can be supplied.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view showing a tungsten wiring structure of a conventional semiconductor device.

FIG. 2 is a vertical sectional side view showing an embodiment of the present invention.

3A to 3C are vertical cross-sectional views showing a process of forming a wiring layer made of a first conductive film into a T-shape.

[Explanation of symbols]

 1-semiconductor substrate 2--diffusion layer 3--first insulating film layer 4--tungsten wiring layer 5--photoresist

Claims (1)

[Claims] 1. A semiconductor device having a first insulating film formed on a semiconductor substrate and a wiring layer made of a first conductive film formed on the first insulating film, wherein the semiconductor device is made of the first conductive film. A semiconductor device having a T-shaped wiring layer.