JPH07249628A - Method of forming wiring - Google Patents

Abstract

PURPOSE:To improve step coverage of Al or Al alloy layer. CONSTITUTION:After an insulating film 12 covering a part to be connected is formed on the surface of a semiconductor substrate 10, a connection hole 12A corresponding with the part to be connected is formed. An Al or Al alloy layer 14 is formed on the upper surface of a substrate via a barrier metal layer 13 by a sputtering method. The substrate temperature during the sputtering process is set at 50-200 deg.C. After that, annealing process is continuously performed at 350-450 deg.C in a reduced pressure atmosphere. Hence the covering state of the Al or Al alloy layer 14 comes to adapt to the step-difference of a connection hole 12A. As another method, the substrate temperature during the sputtering process is set at 350-450 deg.C, and the annealing process may be abolished. After that, wiring layers are obtained by patterning the wiring material layers 13, 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a wiring containing an Al or Al alloy layer and the like.
The step coverage of the alloy layer is improved.

[0002]

2. Description of the Related Art Conventionally, as a wiring forming method for a semiconductor device such as an LSI, there is known a method of depositing an Al or Al alloy layer constituting a wiring by a sputtering method.

FIG. 6 shows a standard sputtering process. After forming a connection hole in the insulating film 12 covering the surface of the semiconductor substrate 10, the upper surface of the substrate is subjected to a sputtering process at a substrate temperature of 50 to 200.degree. The Al or Al alloy layer 14 is deposited by.

FIG. 7 shows a high temperature sputtering process.
After forming the connection holes, the Al or Al alloy layer 14 is deposited on the upper surface of the substrate by sputtering at a high substrate temperature such that Al or Al alloy flows.

[0005]

According to the sputtering process of FIG. 6, there is a disadvantage that the coverage of the lower side wall portion P of the connection hole deteriorates as the size of the connection hole becomes smaller.

Further, according to the sputtering process of FIG. 7, it is possible to embed a fine connection hole, but there is a disadvantage that the film thickness is thin at the opening end Q of the connection hole. This is because the amount of Al supplied is limited with respect to the volume of the connection holes, and the denser the connection holes, the stronger the tendency. Moreover, since the temperature is high, it cannot be used in a connection hole for an upper layer wiring.

An object of the present invention is to provide a novel wiring forming method with improved step coverage of an Al or Al alloy layer.

[0008]

According to the wiring forming method of the present invention, an insulating film is formed on a surface of a substrate so as to cover a connected portion, and then a connection hole corresponding to the connected portion is formed in the insulating film. And a step of covering the connection hole and the insulating film with Al or A
a step of depositing an Al alloy layer, a step of annealing the Al or Al alloy layer at a temperature of 350 to 450 ° C. to provide a covering state adapted to the step of the connection hole, and the Al or Al alloy layer. And a step of forming a wiring layer by patterning after the annealing treatment.

In such a wiring forming method, by setting the substrate temperature during the sputtering process within the range of 350 to 450 ° C., the covering state of the Al or Al alloy layer is adapted to the step difference of the connection hole. Therefore, the annealing process after the sputtering process may be stopped.

[0010]

According to the method of the present invention, since the heat treatment at 350 to 450 ° C. is performed during or after the sputtering process, the Al or Al alloy layer is formed of the contact hole as shown in the layer 14 of FIG. 3, for example. The covered state is adapted to the step. That is, the Al or Al alloy layer does not become thin at the lower side wall of the connection hole as shown in FIG. 6 and does not become thin at the open end of the connection hole as shown in FIG.

[0011]

1 to 4 show a wiring forming method according to an embodiment of the present invention. Steps (1) to (1) corresponding to the respective drawings are shown.
(4) will be sequentially described.

(1) After forming an insulating film 12 on a surface of a semiconductor substrate 10 made of, for example, silicon so as to cover a connection portion such as an impurity-doped region, a connection hole corresponding to the connection portion is formed by photolithography and dry etching. 12A is formed. Then, on the upper surface of the substrate, the Ti layer 13a, the Ti layer 13a
A barrier metal layer 13 is formed by sequentially depositing the N layer 13b and the like.

(2) Next, the connection hole 12A is formed on the upper surface of the substrate.
The insulating film 12 is covered with the barrier metal layer 13 and an Al or Al alloy layer 14 is deposited by sputtering. In this case, the substrate temperature during the sputtering process is 50 to 200 ° C.
Set within the range of.

(3) After the sputtering process, an annealing process is subsequently performed at a temperature of 350 to 450 ° C. in a reduced pressure atmosphere in the sputtering chamber. As a result, the Al or Al alloy layer 14
Is in a covered state adapted to the step difference of the connection hole 12A. According to the research by the inventor, the annealing temperature is 350 to 450 ° C.
It was found that a coating state with good step conformability was obtained when the temperature was in the range of, and the step conformability was lowered when the temperature was out of the range of 350 to 450 ° C.

FIG. 5 shows how the coating state of the Al or Al alloy layer 14 depends on the annealing temperature. It can be seen that a good coating state can be obtained when the annealing temperature is 350 to 450 ° C. In particular, a preferable coating state was obtained at an annealing temperature of 390 to 420 ° C. When the annealing temperature is higher than 450 ° C., the film thickness t of the step portion becomes thin.

(4) After that, the wiring material layer (the lamination of the barrier metal layer 13 and the Al or Al alloy layer 14) is patterned according to a desired wiring pattern by photolithography and etching to form the wiring layer 16. The wiring layer 16 includes the remaining portion 13A of the barrier metal layer 13 and Al.
Alternatively, it is composed of the remaining portion 14A of the Al alloy layer 14 and is connected to the connected portion of the substrate 10 through the connection hole 12A.

As another embodiment of the present invention, in the sputtering process of FIG. 2, the substrate temperature is set in the range of 350 to 450 ° C. to cover the step of the connection hole as shown in FIG. May be obtained. In this case, the annealing process after the sputtering process is unnecessary and the process is simplified.

[0018]

As described above, according to the present invention, Al
Alternatively, since the coating state of the Al alloy layer is adapted to the step difference of the connection hole, the wiring formation yield is improved and the reliability of the wiring is improved.

That is, according to the present invention, the following (a)
The advantages of (d) can be obtained.

(A) A good step coverage can be obtained regardless of the size of the connection holes, or the isolation or density of the connection hole arrangement.

(B) Since the coating state is adapted to the connection hole, the film thickness may be relatively thin. Therefore, it is advantageous for multilayer wiring.

(C) Since the temperature is 350 to 450 ° C., not only the connection hole for the substrate but also the connection hole for the upper layer wiring can be used.

(D) Since the coatability and film quality are good,
Good migration resistance.

[Brief description of drawings]

FIG. 1 is a substrate cross-sectional view showing a barrier metal deposition step in a wiring forming method according to an embodiment of the present invention.

FIG. 2 is a substrate cross-sectional view showing a wiring material attaching step following the step of FIG.

FIG. 3 is a substrate cross-sectional view showing an annealing process following the process of FIG.

FIG. 4 is a substrate cross-sectional view showing a wiring patterning process that follows the process of FIG.

FIG. 5 is a cross-sectional view showing how the coating state of an Al or Al alloy layer depends on the annealing temperature.

FIG. 6 is a substrate cross-sectional view showing an example of a conventional sputtering process.

FIG. 7 is a substrate cross-sectional view showing another example of a conventional sputtering process.

[Explanation of symbols]

10: semiconductor substrate, 12: insulating film, 12A: connection hole, 1
3: barrier metal layer, 14: Al or Al alloy layer, 1
6: Wiring layer.

Claims (2)

[Claims] 1. A step of forming an insulating film on a surface of a substrate so as to cover the connected portion and then forming a connection hole corresponding to the connected portion in the insulating film, and covering the connection hole and the insulating film. A step of depositing an Al or Al alloy layer by means of annealing, and a step of annealing the Al or Al alloy layer at a temperature of 350 to 450 ° C. to provide a covering state adapted to the step of the connection hole; Forming a wiring layer by patterning the alloy layer after the annealing treatment. 2. A step of forming an insulating film on a surface of a substrate so as to cover the connected portion and then forming a connection hole corresponding to the connected portion in the insulating film, and covering the connection hole and the insulating film. In the step of forming an Al or Al alloy layer by a sputtering method by setting the substrate temperature during the sputtering process within a range of 350 to 450 ° C., the covering state of the Al or Al alloy layer of the connection hole is set. A wiring forming method, comprising: forming a wiring layer by patterning the Al or Al alloy layer so as to be adapted to a step.