JPH0322534A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To enhance the electromigration resistance by a method wherein a metallic thin film in small grain size is formed in an electrode contact window and then another metallic thin film in large grain size is laminated on the former thin film so as to form an electrode wiring. CONSTITUTION:A silicon oxide film 2 is formed on a silicon substrate 1 and then the film 2 is patterned to form an electrode contact window 3. Next, an aluminum target 8 and the silicon substrate 1 formed of the electrode contact window 3 are arranged in a vacuum vessel 7 to be sealed with argon gas. Firstly, an aluminum thin layer 4 in small grain size of around several 100Angstrom is sputter-deposited at the pressure of around 8X10<-3>Torr and the power of 0.3kW for 20sec. up to the thickness of 500-1500Angstrom . Next, another aluminum layer 5 in larger grain size of around several mum is sputter-deposited with the gas and pressure left as they are but at the higher power of 3kW up to the thickness of 1mum-1.5mum. Finally, the dual layer thus formed is patterned to form an electrode wiring.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to improvements in electrodes/wirings formed in semiconductor devices and methods of manufacturing the same, particularly improvements in improving the contact of electrodes/wirings formed within small electrode contact windows. The purpose of the present invention is to provide metal electrodes/wirings that have high resistance to electromigration and have good contact with a semiconductor layer, and a method for manufacturing the same. a window is formed, and a first metal layer of a first diameter size is formed at least within the electrode contact window;
This first metal layer is placed on the insulating film including the first metal layer.
A semiconductor device includes a second metal layer having a second grain size larger than the grain size of the second metal layer.

[Industrial application field]

The present invention relates to improvements in electrodes/wirings formed in semiconductor devices and methods of manufacturing the same, and particularly to improvements in improving the contact of electrodes/wirings formed within small electrode contact windows.

[Conventional technology]

Electromigration occurs when the current density flowing through the electrodes and wiring of a semiconductor device increases. Electromigration is a phenomenon in which metal atoms move due to electric current, and in some parts of the wiring, the metal swells up and short-circuits with adjacent wiring, and in some parts, the metal disappears, resulting in disconnection. Generally, the larger the grain size of a metal interconnect, the higher the resistance to electromigration, so a metal layer with a large grain size is used for metal electrodes and interconnects made of aluminum or the like used in semiconductor devices.

[Problem to be solved by the invention]

Refer to FIG. 4 By the way, as shown in FIG. 4, for example, when an aluminum electrode/wiring 5 is formed in an electrode contact window 3 formed in a silicon dioxide insulating film 2 on a silicon layer 1, aluminum When the grain size of the layer is large, silicon tends to diffuse into the grain boundaries, so in the subsequent heating step, as shown in FIG. When the electrode contact window 3 is as small as about 17n openings, the contact between the electrode/wiring 5 and the silicon layer 1 becomes defective.

The purpose of the present invention is to overcome this drawback and has two independent objectives. The first objective is to provide a metal electrode/wiring that has high resistance to electromigration and has good contact with a semiconductor layer. A second object is to provide a method for manufacturing the metal electrode/wiring described above.

[Means to solve the problem]

Of the above two purposes, the first purpose is to
An insulating film (2) is formed on top, and this insulating It! an electrode contact window (3) is formed in the electrode contact window (3);
A second metal layer (4) having a second grain size larger than the first grain size is formed on the insulating film (2) including on the first metal layer (4). Layer (5)
This is accomplished by semiconductor devices in which

Of the above two objectives, the second objective can be achieved by any of the following means.

The first method is to form an insulating film (2) on a semiconductor layer (1), form an electrode contact window (3) on this insulating film (2), and perform sputtering using a power lower than the rated value. forming a first metal layer (4) of a first diameter size at least within said electrode contact window (3) using a method;
Next, using a sputtering method using rated power, the insulating film (
2) A second metal layer (5) having a second grain size larger than the first grain size is formed on top of the first grain size.
This is a method for manufacturing a semiconductor device, which includes a step of patterning the second metal layers (4) and (5) to form electrodes and wiring.

The second means is to provide insulation 11! on the semiconductor layer (1). (2) is formed, an electrode contact window (3) is formed on this insulating film (2), and at least A first metal layer (4) of a first grain size is formed within the electrode contact window (3), and then a sputtering method is used using an inert gas not containing nitrogen as a sputtering gas. and a second metal layer (5) having a second grain size larger than the first grain size on the insulating film (2) including on the first metal layer (4).
This method of manufacturing a semiconductor device includes the steps of forming electrodes and wiring by patterning the first and second metal layers (4) and (5).

A third method is to form an insulating film (2) on the semiconductor layer (1), form an electrode contact window (3) on this insulating film (2), and use a bias sputtering method to form at least the above-mentioned forming a first metal layer (4) of a first diameter size within the electrode contact window (3), then using a sputtering method, including over said first metal layer (4); A second metal layer (5) having a second grain size larger than the first grain size is formed on the insulating film (2), and the first and second metal layers (4) and (5) are formed on the insulating film (2). This is a method for manufacturing a semiconductor device, which includes a step of patterning a semiconductor device to form electrodes and wiring.

[Function] The inventor of the present application formed an argonium layer having several different grain sizes on an electrode contact window formed in an insulating film formed on a silicon substrate, and heat-treated the argonium layer to form an aluminum layer. As a result of measuring the contact resistance with the silicon substrate, they discovered a natural law that the smaller the grain size of the aluminum layer, the lower the contact resistance. This is considered to be because when the dalein size is small, it is difficult for silicon to diffuse into the grain boundaries, so that silicon does not precipitate in a large amount.

In the semiconductor device and the manufacturing method thereof according to the present invention,
This method takes advantage of the above natural law, and first forms a thin layer of metal such as aluminum with a small dalein size within the electrode contact window, and then silicon, etc. precipitates into the metal layer such as aluminum. At the same time, by forming an electrode/wiring made of a metal layer such as aluminum with a large grain size on this thin metal layer, resistance to electromigration can be increased. It is something to do.

Note that the metal layer having a small duplex size is formed by lowering the sputtering speed.

〔Example〕

Hereinafter, three embodiments of electrode/wiring shapes and methods according to the present invention will be described with reference to the drawings.

1. A silicon dioxide film 2 is formed on a silicon substrate 1, and is patterned to form an electrode contact window 3. Referring to FIG.

See also FIG. 2. FIG. 2 is a structural diagram of a sputtering apparatus. An aluminum target 8 and a silicon substrate 1 on which the electrode contact window 3 is formed are placed in a vacuum container 7, argon gas is filled in the vacuum container 7, the silicon substrate 1 is grounded, and a negative voltage of several 100 V is applied to the aluminum target 8. A voltage of 1 is applied to perform sputtering to form an aluminum layer on the silicon substrate 1.

First, argon gas was introduced and the temperature was 8
The pressure was set to about 0.3 kW, the power was set to 0.3 KW, and the mixture was blown away for about 20 seconds. With this Icho, 500~L of aluminum ξ thin layer 4 with a small grain size of about 100 grains is used.
It is 500 people thick. Next, the gas and pressure remain the same, the power is set to 3KW, and the grain size is about several microns (2 to 10 nm).
) and a large aluminum layer 5 is formed to a thickness of 1 pm to 1.5 pm. The thus formed double layer of the aluminum thin layer 4 with a small daimé size and the aluminum ξ layer 5 with a large daimyan size is patterned using a well-known lithography technique to form electrodes and wiring.

As in the first example, the sputtering device shown in FIG. 2 is used. A few hundred ppm of nitrogen was added to the argon gas at a pressure of 8 x 10-3 Torr, and sputtering was performed at a power of 3 to 6 kW to form a thin aluminum layer 4 with a small dalein size similar to that of the first example. take shape

Thereafter, the addition of nitrogen is stopped, and the aluminum thin layer 5 having a large grain size is formed in the same manner as in the first example.

Using a piercing bias bias sputtering device, introducing argon gas l2, 8 X I O-'' Torr, power 3 to 6 K.
Then, a high-frequency voltage (DC or RF) is applied to the stage on which the wafer 1 is placed to perform sputtering to form a thin aluminum layer 4 having a small grain size. The bias voltage is, for example, about 200V. Thereafter, the bias voltage is lowered or made zero to lengthen the aluminum thin layer 5 having a large grain size in the same manner as in the first example.

As shown in FIG. 3, a bias sputtering device is a device that simultaneously applies a negative voltage to an aluminum target 8.
This device also applies a negative high-ass voltage to the silicon substrate 1 to perform sputtering.

〔Effect of the invention〕

As explained above, in the semiconductor device and the manufacturing method thereof according to the present invention, the first metal layer has a first grain size in which silicon and the like are difficult to precipitate, and a grain size smaller than the first grain size. It is known that a double layer is formed with the second metal layer which is large in size and has high resistance to electromigration, so it is possible to form an electrode/wiring that has good contact with the semiconductor layer and has high resistance to electromigration. The manufacturing method is realized. In addition, as a result of carrying out an accelerated heating test, a change in contact resistance was undetectable, and good results were obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an electrode/wiring according to an embodiment of the present invention. FIG. 2 is a structural diagram of the sputtering apparatus. FIG. 3 is a diagram showing the structure of the bias sputtering apparatus. FIG. 4 is a cross-sectional view of electrodes and wiring according to the prior art. ...semiconductor substrate, ...insulating film, ...electrode contact window, ...first metal layer with first diameter size, ...second metal layer with second diameter size, ...precipitated. Silicon, 7. Vacuum container, 8. Target.

Claims (1)

[Claims] [1] An insulating film (2) is formed on the semiconductor layer (1), an electrode contact window (3) is formed in the insulating film (2), and at least the electrode contact window (3) a first metal layer (4) having a first grain size is formed within the insulating film (2) including on the first metal layer (4); A semiconductor device characterized in that a second metal layer (5) having a grain size of 2 is formed. [2] Forming an insulating film (2) on the semiconductor layer (1), forming an electrode contact window (3) on the insulating film (2), and using a sputtering method using a power lower than the rated value. forming a first metal layer (4) of a first grain size in at least the electrode contact window (3); forming a second metal layer (5) having a second grain size larger than the first grain size on the insulating film (2) including on the layer (4); A method for manufacturing a semiconductor device, comprising the step of patterning layers (4) and (5) to form electrodes and wiring. [3] Form an insulating film (2) on the semiconductor layer (1), form an electrode contact window (3) on the insulating film (2), and use an inert gas containing a trace amount of nitrogen as a sputtering gas. A first metal layer (4) of a first grain size is formed at least within the electrode contact window (3) using a sputtering method using a nitrogen-free inert gas as a sputtering gas. The insulating film (
2) Form a second metal layer (5) with a second grain size larger than the first grain size on top, and pattern the first and second metal layers (4) and (5) to form electrodes. A method for manufacturing a semiconductor device, comprising the step of forming wiring. [4] An insulating film (2) is formed on the semiconductor layer (1), an electrode contact window (3) is formed on the insulating film (2), and at least the electrode contact window (3) is formed using a bias sputtering method. 3) forming a first metal layer (4) of a first grain size within the insulating film (2) including on the first metal layer (4) using a sputtering method; forming a second metal layer (5) with a second grain size larger than the first grain size; patterning the first and second metal layers (4) and (5) to form electrodes and wiring; 1. A method for manufacturing a semiconductor device, comprising the step of: