JPS63132457A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To increase the insulating property between layers of a multilayer interconnection, by oxidizing a part of a first conductive layer after the first conductive layer is formed on a substrate on which elements are formed, and by forming a second insulating layer and a second conductive layer thereon. CONSTITUTION:On a silicon substrate 1 on which a semiconductor element is formed, a metal layer 3 of aluminum is formed via a silicon oxide film 2. A first insulating film 4 is formed by oxidizing a part of the surface of the layer 3. Resist is spread on the whole surface of the layer 4, and the layer 3 is eliminated by photolithography leaving a pattern of the first conductive layer. After the resist is eliminated, a second insulating layer 7 is deposited on the substrate 1 via the film 2 containing the pattern 3. After the layer 7 is made flat, an insulating layer 9 between conductive layers is formed, and a contact hole 10 is made. Then a second conductive layer 11 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device having multilayer wiring, and in particular to a method for manufacturing a semiconductor device having a multilayer wiring, and particularly to a method for forming a good interlayer insulating layer between a first conductive layer and an 8g2 conductive layer '1i. Regarding the manufacturing method.

[Conventional technology]

With the progress of fine technology, semiconductor devices with multilayer wiring
t is required, but the insulation between conductive layers is a problem.

Conventionally, in order to insulate between conductive layers, there is a method of depositing an insulating layer on a first conductive layer, flattening the layer, and then forming a second conductive layer. That is, a conductive layer of aluminum alloy containing silicon or steel is formed on a semiconductor substrate on which a semiconductor element is formed, and a first conductive layer is formed according to a desired wiring pattern.
Form a conductive layer.

Next, an insulating film such as silicon oxide or silicon nitride film is deposited by a low temperature plasma method at approximately 300'O. Thereafter, a resist made of a material having approximately the same etching rate as the deposited insulating film is applied to form a pattern, and then anisotropic etching is performed by RIE to flatten the surface of the insulating film. An insulating film is again deposited on this insulating film by low-temperature plasma deposition to form an insulating layer between the conductive layers. On top of this, a second Nj-th conductive layer of aluminum alloy is formed.

In such conventional manufacturing methods, aluminum, which is a material used for the conductive layer, is recrystallized by the heat applied during the deposition of the insulating layer, resulting in protrusions called hillocks on the surface of the first conductive layer. Although the deposition temperature of plasma CVD is set at a low temperature, at temperatures above approximately 200"C, protrusions are formed, causing a short circuit between the first conductive layer and the second conductive layer, and destroying the insulation between the conductive layers. .

Furthermore, the problem of hillock occurrence is particularly pronounced in memory areas, logic areas, etc., where the elements are arranged more densely than in areas where the elements are arranged sparsely, because the insulating film is thinner.

Further, as a technology related to the interlayer insulating layer structure of the present invention, ``Method for manufacturing multilayer wiring structure'' published in Japanese Patent Publication No. 58-2451
There is a technique known in the art in which a solution containing an aluminum chelate compound is applied to the surface of a substrate including a first conductive layer, and then heat-treated to form an alumina film. However, this technique differs from the present invention in that it applies a solution to the surface of the conductive layer and heat-treats it, and the process of heat-treating cannot prevent the occurrence of hillocks. Inventions are technologies that differ in purpose and effect.

[Problem that the invention seeks to solve]

In conventional semiconductor devices with multilayer wiring, after forming the first conductive layer, an insulating layer is deposited by low-temperature plasma CVD, so pinholes are formed in the insulating layer. ) had formed protrusions on the wiring surface. Further, during the process of forming a multilayer wiring having two or more layers, metal impurities from the second conductive layer were diffused. Such protrusions and metal impurity diffusion destroy the insulation between conductive layers, greatly reducing the reliability of semiconductor devices.

The object of the present invention is to prevent the formation of protrusions on the tetraelectric layer, the diffusion of metal impurities and the generation of pinholes in the conductive layer, and to form a stable insulating layer between the tetraelectric layers.

[Means for solving problems]

According to the present invention, a first
A conductive layer is formed, and at least a portion of the surface of the 4it layer is oxidized at a low temperature to form a first insulating layer on the surface of the first conductive layer. Subsequently, after forming a second insulating layer, a second wiring layer is formed thereon to manufacture a semiconductor device having multilayer wiring.

[For production]

As described above, the present invention forms a first insulating layer by directly oxidizing at least a portion of the surface of the @1 conductive layer at a low temperature, and insulates the first insulating layer by plasma CVD on the conventional first conductive layer. Before depositing the layers, the surface of the conductive layer is protected with a first insulating layer.

〔Example〕

An embodiment of the present invention will be described with reference to FIG.

A silicon oxide film 5i02 for separating an element region and a conductive layer region on a silicon substrate 1 on which a semiconductor element is formed.
An allure containing silicon, steel, or the like is formed via 2, and conducts the contact portion of the semiconductor element and the first conductive layer. Next, as shown in FIG. 1, a part of the surface of the aluminum metal layer 3 is oxidized by an anodic oxidation method to form a first insulating layer 4 made of aluminum oxide Kl 203 having a thickness of 2000X or less.

The conditions for anodic oxidation are approximately 100 to 20
A voltage of 0V is applied and the test is carried out at room temperature. This anodic oxidation is carried out at a temperature at which no protrusions are formed on the surface of the aluminum alloy metal layer 3, preferably at 200°C or lower.

Next, a resist 5 is applied to the entire surface of the first insulating layer 4 of Al2O3, and a photolithographic process is performed according to the wiring pattern of the 14th conductive layer, leaving only a portion of the first conductive layer 6 as shown in FIG. 1C. Remove the aluminum metal layer 3. Next, resist 5
After removing the first conductive layer 6, a second insulating layer 7 of silicon oxide 5102s silicon nitride Si3N4, etc. is deposited on the semiconductor substrate 1 via the 5to2 film 2 including the first conductive layer 6 by low-temperature plasma deposition. 1 d), then deposited second insulation 1g! A resist 8 made of a material having approximately the same etching rate as 7 is selected and coated on the second insulating layer 7 (
Figure 1 e). Subsequently, the surface of the second insulating layer 7 is planarized by etching using the RIE (Anisotropic Etching) method as shown in FIG. 1F. Next, the same insulator as the second insulating layer is deposited again using the low-temperature plasma method to form the conductive interlayer insulating layer 9. Subsequently, after forming a contact hole 10 for electrical connection between the first conductive layer and the second conductive layer, a second conductive layer 11 made of an aluminum alloy containing silicon, copper, etc. is formed (see Fig. 1g). ). If the layer is further multi-layered, the surface of the 24th layer 11 is made into the first layer. The surface of the Jt layer is treated in the same manner as the surface, and the process described above is repeated.

The semiconductor device manufactured by the method explained above has the first
After forming the four conductive layers, the surface of the first conductive layer is directly oxidized at a temperature at which no protrusions are formed, preferably at 200'0 or less, to form an insulating film of metal oxide, and then oxidized as before. Even if the insulating layer is deposited using the plasma method described above, it is possible to prevent the formation of protrusions on the surface of the conductive layer. This insulating layer is a conductive layer itself partially oxidized, and has good adhesion to wiring. Furthermore, since the metal oxide insulating film formed on the surface of the conductive layer is dense, it is possible to protect the metal wiring from pinholes and the like that occur in the insulating layer deposited thereon by a drawing method. Furthermore, dielectric breakdown due to diffusion of metal impurities from the upper conductive layer to the conductive interlayer insulating layer can be prevented by the insulating layer obtained by oxidizing the lower conductive layer.

As described above, the manufacturing method of the present invention can be manufactured using conventional equipment except for the step of oxidizing the entire surface of the first conductive layer. Although the number of steps is one more than the conventional method, the anodic oxidation method allows easy oxidation and is highly effective in preventing the formation of protrusions.

In this embodiment, an anodic oxidation method is used as a method for oxidizing the surface of the first conductive layer, but the method is not limited to this method. In this case, it is preferable to carry out the oxidation at zoa''c or less, but any method that does not cause the formation of protrusions may be used.

For example, there is a method of forming a first conductive layer according to a wiring pattern and then placing it in an oxidizing plasma atmosphere to oxidize the surface of the first conductive layer. Although this method requires more difficult steps than the anode+1 method, similar effects can be obtained. Further, as shown in FIG. 2, since the entire surface of the first conductor 1 of the wiring pattern can be oxidized, an oxide film can also be formed in the lateral direction, and the conductive layer can be sufficiently protected.

Further, the metal used for the conductive layer of the present invention is not limited to aluminum alloy, and any metal can be used.

〔Effect of the invention〕

According to the present invention, since the generation of protrusions due to heat applied during the deposition of the insulating layer can be prevented, it is possible to manufacture a semiconductor device with good upper edge properties between conductive layers and high M-type properties.

[Brief explanation of the drawing]

FIG. 1 shows one embodiment of the invention, and FIG. 2 shows another embodiment. DESCRIPTION OF SYMBOLS 1... Semiconductor substrate, 2... 5L02 layer, 3... First conductive IT layer, 4... Metal oxide layer, 9... 4 Interlayer insulation layer, 11... Second wiring layer . (a) ([)) (C) (d) Figure 1

Claims (2)

[Claims] (1) a step of forming a first conductive layer on a semiconductor substrate on which a semiconductor element is formed; a step of oxidizing at least a portion of the surface of the first conductive layer to form a first insulating layer;
A method for manufacturing a semiconductor device, comprising the steps of: forming a second insulating layer on the insulating layer; and forming a second conductive layer on the second insulating layer. (2) The semiconductor device according to claim 1, wherein the step of forming the first insulating layer oxidizes at least a portion of the surface of the first conductive layer using an anodic oxidation method. Production method.