JP2723023B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, aluminum (A) of a semiconductor device has been used.
1) The wiring in the upper and lower connection holes (contact holes to the substrate and vias of the multilayer wiring) in the copper (Cu) -based wiring is, as shown in FIG.
And has been formed of an Al-Cu alloy having the same composition.

[0003]

With the miniaturization of Al wiring, measures against electromigration have become increasingly important. Conventionally, addition of Cu has been used as a standard measure against electromigration of Al wiring. However, since the addition of Cu lowers the corrosion resistance of the Al wiring, the wiring is likely to be corroded in the Al-Cu alloy pattern forming step by the dry etching method. Therefore, although it is desirable to use an Al—Cu alloy having a Cu concentration of about 1 to 4% by weight from the viewpoint of electromigration resistance, it is preferable to use 0% in order to avoid corrosion during dry etching and a decrease in dry etching property. 0.5% by weight
We had to use a low concentration alloy.

On the other hand, Japanese Patent Application Laid-Open No. 63-253644 discloses another method of forming a wiring by using a metal having a partially different material depending on electrical characteristics including electromigration resistance and operation speed. ing.
However, as described in the publication, it is necessary to locally change the Cu concentration in a plane wiring in which a portion containing Cu at a high concentration is to be formed in the wiring on the same plane, which is suitable for mass production at present. The method is hard to imagine. Further, even if a high-concentration Cu region can be partially formed in a state of a film before being processed into wiring, the problem of dry etching described above is encountered.
Even if the problem of dry etching can be overcome, this method targets only a portion having a clearly low electromigration resistance, such as a bonding portion or a power line, as described in the same publication. It is clear that this portion is intended to ensure the same level of electromigration resistance as the other portions having a low Cu concentration. Therefore, the electromigration resistance of most of the wirings remains the same as before, and no countermeasure has been taken at all for a portion of the wiring which has a low electromigration resistance stochastically.

It is an object of the present invention to provide these conventional Al-C
It is an object of the present invention to provide a new wiring structure in which a problem in u-type wiring is greatly improved.

[0006]

In order to achieve the above object, the present invention is characterized in that the Cu concentration of the Al alloy wiring in the upper and lower connection holes is higher than the Cu concentration of the Al alloy wiring in the layer. Is what you do.

[0007]

When the Al-Cu alloy wiring structure of the present invention is used,
Since Cu is transported from the upper and lower connection holes having a high Cu concentration to the wiring in the layer connected thereto due to thermal diffusion in a heating step or electromigration in actual use, the Cu concentration in the wiring in the layer is the same as that of the conventional structure. Has been substantially enhanced. Therefore, resistance to electromigration and stress migration is improved. Also, C
In forming the connection hole having the u concentration, a method for removing the entire surface, such as chemical mechanical polishing, can be applied.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. Using manufacturing techniques standard integrated circuits, as shown in schematic cross-sectional view of FIG. 1, after providing the n ⁺ impurity region in the p-type silicon substrate 17, a silicon oxide film is deposited 13, n
A contact hole 14 to the ⁺ region is opened. Next, after titanium (Ti) is deposited on the entire surface to a thickness of about 600 angstroms, a heat treatment is performed in a nitriding atmosphere such as a mixed gas of nitrogen and hydrogen, and a reaction between part of Ti in contact with the silicon substrate and silicon causes the reaction shown in FIG. Ti silicide 1
6 is formed in a contact self-alignment manner, and Ti on the surface and the insulating film 13 is converted into titanium nitride 15. Next, as shown in FIG. 3, an Al—Cu alloy 17 containing approximately 46% by weight of Cu and substantially having a composition of CuAl ₂ was deposited. Next, the Al-C on the insulating film 13 is formed using a standard chemical mechanical polishing (Chemical Mechanical Polish: CMP) method.
By removing the u-alloy and the titanium nitride film, as shown in FIG.
A contact structure composed of the contained Al-Cu alloy 17 'is formed. Next, as shown in FIG. 5, as the first layer wiring, an Al—Cu alloy 18 containing 0.5% by weight of Cu was used.
And a multilayer structure wiring made of titanium nitride 19 is formed by a standard method. Further, as shown in FIG.
After forming an interlayer insulating film 20 of silicon oxide or the like and opening vias (upper and lower layer connection holes), a high concentration Cu-containing Al-Cu alloy via It is possible to form a second-layer laminated wiring composed of the wiring 21 and the Al—Cu alloy 22 having a standard Cu content and the titanium nitride 23.
At this time, the portion exposed at the opening of the titanium nitride 19 was removed, but it may be left without being removed. By repeating the above-described second layer wiring forming method, a multilayer wiring of three or more layers can be formed. The Al-Cu alloy wiring formed according to the present example exhibited twice or more electromigration resistance as compared with the conventional wiring composed of only Al-0.5% by weight Cu. In the above embodiment, the Cu concentration in the upper and lower connection holes is set to about 4
Although the case of 6% by weight is shown, even at a concentration of several% by weight, the electromigration resistance can be improved as compared with the conventional single composition wiring having a Cu concentration of 0.5% by weight. Further, addition of other elements such as silicon in addition to Cu does not impair the effectiveness of the structure of the present invention.

[0009]

As described above, according to the present invention,
By increasing the Cu concentration in the upper and lower layer connection holes of the Al-Cu alloy wiring system, C
Since u is supplied, the migration resistance of the wiring is improved, and a highly reliable Al—Cu-based wiring can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a cross section of a sample in a main manufacturing process in an example of the present invention.

FIG. 2 is a schematic diagram of a sample cross section in a main manufacturing process according to an example of the present invention.

FIG. 3 is a schematic diagram of a sample cross section in a main manufacturing process according to an example of the present invention.

FIG. 4 is a schematic diagram of a sample cross section in a main manufacturing process in an example of the present invention.

FIG. 5 is a schematic view of a cross section of a sample in a main manufacturing process in an example of the present invention.

FIG. 6 is a schematic diagram of a cross section of a sample in a main manufacturing process in an example of the present invention.

FIG. 7 is a schematic sectional view of a conventional structure.

[Explanation of symbols]

11, 31 Silicon substrate 12, 32 n ⁺ region 13, 33 Silicon oxide film 14 Contact hole 15, 15 ', 19, 23, 35 Titanium nitride 16, 34 Titanium silicide 17, 17', 21 Aluminum / copper alloy (high copper Concentration) 18, 22, 36 Aluminum / copper alloy (low copper concentration)

Claims (7)

(57) [Claims] A wiring in a contact hole to a substrate and a first wiring.
A semiconductor device having an aluminum alloy in each of the layer wirings
The aluminum alloy of the wiring in the contact hole is
The aluminum of the first layer wiring is formed in the entire area inside the contact hole.
Containing a higher concentration of copper than the copper concentration in the
Aluminum alloy for wiring in contact hole and
Luminium alloy contacts at the top surface of the contact hole
A semiconductor device characterized by the above-mentioned. 2. Arrangement in a connection hole between upper and lower layers in a multilayer wiring.
Aluminum alloy for each wire and in-layer wiring
In a semiconductor device having a multilayer wiring structure,
Aluminum alloy is the upper layer wiring in the entire area of the connection hole
Copper concentration in aluminum alloys for both lower and upper wiring
Containing copper at a higher concentration than the aluminum
Alloy and the aluminum of the upper wiring and the lower wiring
Gold contacts the top and bottom surfaces of the connection holes, respectively.
A semiconductor device characterized by the following. 3. Wiring in a contact hole to a substrate, multilayer wiring
In the connection hole between the upper and lower layers and that in the layer
Semiconductors with multi-layer wiring structures each having an aluminum alloy
In the device, Aluminum alloy for wiring in contact hole is contact hole
In the aluminum alloy of the first layer wiring
Contains copper at a concentration higher than the copper concentration, and
Aluminum alloy of wiring and aluminum of first layer wiring
Gold is in contact with the upper end surface of the contact hole, The aluminum alloy of the wiring in the connection hole covers the entire area in the connection hole
Aluminum for both upper and lower wiring
Containing copper at a higher concentration than the copper concentration in the alloy,
The inner wiring aluminum alloy and the upper wiring, the lower wiring
Aluminum alloy on the upper and lower surfaces of the connection hole respectively
A semiconductor device, which is in contact with the semiconductor device. 4. The method according to claim 1, wherein
Wiring in the contact hole in the semiconductor device of
Copper contained in the aluminum alloy of the wiring in the connection hole
Can be caused by heat diffusion or electromigration.
Semiconductor device transported into the intra-layer wiring
Place. 5. The one of claims 1 to use aluminum and copper intermetallic compound as the aluminum alloy of the contact hole wiring or the contact <br/> the connection hole interconnection of claim 4
13. A semiconductor device according to claim 1. 6. A semiconductor substrate having an impurity region formed thereon.
Depositing an edge film and reaching the impurity region in the insulating film.
Opening a contact hole to be formed;
Fill aluminum alloy containing copper with uniform concentration distribution
And forming the contact hole from the upper end surface of the contact hole.
The upper aluminum alloy is removed by chemical mechanical polishing.
Removing the aluminum alloy in the contact hole
Insulation using aluminum alloy with lower copper concentration than
Forming a first layer wiring on the film.
A method for manufacturing a semiconductor device. 7. Manufacturing of a semiconductor device having a multilayer wiring structure.
In the method, the lower wiring made of aluminum alloy is formed.
Forming an interlayer insulating film on the lower wiring after the formation
Opening a connection hole in the upper and lower layers in the interlayer insulating film;
The connection hole contains copper in a uniform concentration distribution and the lower layer
Aluminum with higher copper concentration than aluminum alloy of wire
Burying and forming an alloy; and
The upper aluminum alloy by chemical mechanical polishing
Removing the aluminum alloy in the connection hole
The interlayer insulation using aluminum alloy with low copper concentration
Forming an upper layer wiring on the film.
Manufacturing method of a semiconductor device.