JPH06177067A - Manufacture of semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To form a low-resistance impurity diffusion layer by capturing impurities which are absorbed by a high melt-point metal layer in the process for manufacturing a semiconductor integrated circuit device with a high melt-point metal silicide layer on a diffusion layer. CONSTITUTION:After a first impurity diffusion layer 10a is formed, titanium film is formed by sputtering and then titanium silicide layer 14 is formed by RTA treatment at 700 deg.C. Then, boron is ion-implanted and RTA treatment is performed again for forming a second impurity diffusion layer 19, thus suppressing the reduction in impurity concentration on the diffusion layer and obtaining a low-resistance diffusion layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor integrated circuit device, and more particularly to a method for manufacturing a semiconductor integrated circuit device having a refractory metal silicide layer on an impurity diffusion layer.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a semiconductor integrated circuit device having a refractory metal silicide layer on an impurity diffusion layer, a method of forming a refractory metal silicide layer and then performing ion implantation to form an impurity diffusion layer. On the contrary, a method of forming a refractory metal silicide layer after forming an impurity diffusion layer has been proposed. In the former case, refractory metal atoms are knocked on at the time of ion implantation and enter the semiconductor substrate, becoming the most coupling center and increasing leakage current. This leakage current can be reduced by providing the junction with the impurity diffusion layer at a deep position, but this is incompatible with the trend toward higher speed semiconductor devices.

For the latter, the following steps are generally adopted.

As shown in FIG. 5A, a gate oxide film 3 is formed in an active region defined by forming a field oxide film 2 on the surface of an N-type silicon substrate 1, a polysilicon film 4 and a tungsten film. The gate electrode 6 is formed by sequentially depositing and patterning the silicide film 5.
Next, boron ions are implanted to form a low-concentration ion implantation layer 7, and then a spacer 8 such as a silicon oxide film is formed on the side wall of the gate electrode 6, and a silicon oxide film 9 having a thickness of 30 nanometers is chemically formed on the entire surface. It is formed by a vapor phase growth method. Next, by the ion implantation method, boron difluoride ions having a dose amount of 10 ¹⁵ to 10 ^{16 to} cm ⁻² are implanted at an energy of 30 to 70 keV to form the high concentration ion implantation layer 10. Next, in a nitrogen atmosphere at 800 to 900 ° C.,
Heat treatment is performed for about 10 minutes to activate the implanted ions, and as shown in FIG. 5B, a low concentration impurity diffusion layer 7a and a high concentration impurity diffusion layer 10a are formed.

Continuing, as shown in FIG. 6 (a), an opening 11 is provided in a region including at least the high-concentration impurity diffusion layer 10a in which the refractory metal silicide layer is provided to expose the silicon substrate. And by the sputtering method,
After forming the titanium film 12 having a thickness of 30 to 100 nanometers on the entire surface, in a nitrogen atmosphere at 600 to 700 ° C.,
A short-time annealing (RTA) process for 30 seconds is performed to form a titanium silicide layer 14 by a silicidation reaction in a portion where the titanium film and the silicon substrate are in direct contact with each other. Continued,
After removing the unreacted titanium film 12 layer remaining on the silicon oxide films 8 and 9, the tungsten silicide film 5 and the titanium silicide layer 14 by etching using an etching solution composed of ammonia and hydrogen peroxide, RTA treatment is performed in a nitrogen atmosphere to reduce the resistance of the titanium silicide layer 14. In the step of forming the titanium silicide layer 14, a low concentration layer 13 in which boron atoms are absorbed in the titanium silicide layer 14 from the high concentration impurity diffusion layer 10a is formed.

After that, as shown in FIG.
After forming the 00 nanometer BPSG film, heat treatment is performed in a nitrogen atmosphere at 850 ° C. to form the interlayer insulating film 15. Then, an opening is provided at a predetermined position, an aluminum film or the like is formed by a sputtering method, and patterning is performed to form wirings 17-1 and 17-2.

[0007]

In the method of forming the titanium silicide layer in the above-described conventional method of manufacturing a semiconductor integrated circuit device, the titanium silicide is formed by a chemical reaction between the silicon layer in which the impurity diffusion layer is formed and titanium. Since the layer is formed, the boron atoms in the impurity diffusion layer formed in the silicon substrate are absorbed by the titanium silicide layer during the reaction, and the effective concentration of boron is reduced. As a result, non-ohmic characteristics are generated in the contact portion provided on the diffusion layer. In addition, a parasitic resistance appears in the transistor characteristics, which causes a problem such as a decrease in on-current.

[0008]

A method of manufacturing a semiconductor integrated circuit device according to the present invention comprises a first surface portion of a semiconductor silicon substrate.
A first step of selectively implanting first and second conductivity type impurity ions into a conductivity type region and performing a first heat treatment to form an impurity diffusion layer; and depositing a refractory metal film on the impurity diffusion layer. And a second step of performing a second heat treatment to form a refractory metal silicide layer and removing a portion of the refractory metal film that remains unsilicided, and before or after the second step. It includes a third step of implanting second impurity ions of the second conductivity type into the impurity diffusion layer and a step of performing a third heat treatment.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. 1 (a), (b), 2 (a), (b)
3A to 3D are sectional views in order of the processes, for illustrating the first embodiment of the present invention.

After removing the unreacted titanium layer 12 in the conventional example described with reference to FIGS. 5 (a), 5 (b) and 6 (a), boron ions are used as second impurity ions 15
Implantation is performed with an energy of ˜30 keV to form a boron ion implantation layer 18 in the low concentration layer 13 as shown in FIG. The dose amount is preferably about 1 × 10 ¹⁴ cm ^-2 . Continuing, the second RTA treatment is performed in a nitrogen atmosphere at 800 to 850 ° C. to perform the titanium silicide layer 14
And the activation of the boron atoms implanted by the second ion implantation, as shown in FIG.
The second high concentration impurity layer 19 is formed.

After that, by a chemical vapor deposition method, as shown in FIG.
As shown in (a), BPSG with a thickness of 500 nanometers
After forming the film, the film is placed in a nitrogen atmosphere at 850 ° C. for 30
Heat treatment for 1 minute to reflow the BPSG film,
The interlayer insulating film 15 is formed. Further, after applying a photoresist, an opening is provided on the titanium silicide layer 14 by a photolithography technique as shown in FIG.
An opening 16 reaching the substrate is provided by sequentially performing etching with an HF-based etching solution and CF ₄ -based gas plasma. Subsequently, an aluminum film or the like is formed by the sputtering method, and the wirings 17-1 and 17-2 are formed by the photolithography technique and etching in Cl-based gas plasma.

According to this embodiment, after the titanium silicide layer 14 is formed on the first high-concentration impurity diffusion layer 10a, boron is implanted again by the second ion implantation. Therefore, when the titanium silicide layer is formed, The boron concentration taken into this titanium silicide layer is supplemented, and a high diffusion layer concentration is obtained. Further, by performing the second RTA process after performing the second boron implantation, the boron atoms implanted by the second boron implantation are activated at the same time.

Next, a second embodiment of the present invention will be described. The second embodiment uses a second boron implant of 15 k
It has the same contents as the first embodiment except that it is performed twice at energies of eV and 30 keV.

This embodiment comprises the following process steps. First, as shown in FIG. 3A, the first impurity diffusion layer 10a and the titanium silicide layer 14 are formed by the same method as in the first embodiment. Then, after removing the unreacted titanium layer, as the second ion implantation, for example, boron ions at an energy of 15 keV of 1 × 10 ¹⁴ cm ^−2.
To form a first boron ion-implanted layer 20, and then, as a second ion implantation, an implantation of 5 × 10 ¹³ cm ⁻² with an energy of 30 keV is performed as shown in FIG. 3 (b). The second boron ion implantation layer 21 is formed at an angle of 30 °. Then, a second RTA process is performed in a nitrogen atmosphere at 800 to 850 ° C. to reduce the resistance of the titanium silicide layer 14 and activate the boron atoms implanted by the second and third ion implantations. Figure 3 (c)
As shown in, the second high-concentration impurity diffusion layer 13 and the third high-concentration impurity diffusion layer 22 are formed. According to the present embodiment, the third high-concentration impurity diffusion layer 22 has a shallow concentration peak and a deep concentration peak. Even when such a high temperature heat treatment is performed, boron is further prevented from being taken into the tungsten silicide layer to form a diffusion layer having a low impurity concentration.

Further, a third embodiment of the present invention will be described. The third embodiment has the same contents as the first embodiment except that the titanium silicide layer is formed after the second impurity implantation is performed in advance on the titanium film formed by the sputtering method. . Next, the process procedure of this embodiment will be described below.

First, as in the conventional example, as shown in FIG. 4A, the first high-concentration impurity diffusion layer 10a is formed.
Then, the opening 11 is provided at least in the region including the impurity diffusion layer in which the titanium silicide layer is provided to expose the silicon substrate. Then, a titanium film 12 having a thickness of 30 to 100 nanometers is formed on the entire surface by a sputtering method.
Then, as a second impurity implantation, boron is added at 15 keV,
Implantation is performed under the condition of 1 × 10 ¹⁵ cm ⁻² . As a result, a boron-implanted titanium layer and a boron ion-implanted layer 18a are formed. Then, a first RTA treatment is performed for 30 seconds in a nitrogen atmosphere at 600 to 700 ° C. to form a titanium silicide layer 14a only on the silicon substrate as shown in FIG. 4B. Then, after removing the unreacted titanium film by etching using an etching solution containing ammonia and hydrogen peroxide, a second RTA treatment is performed in a nitrogen atmosphere at 800 to 850 ° C. to reduce the resistance of the titanium silicide layer and The boron atoms are activated to form the second high-concentration impurity diffusion layer 19a.

According to this embodiment, since boron is previously implanted as an impurity in the titanium layer formed by the sputtering method, even during the formation of the titanium silicide layer and the subsequent heat treatment at 800 ° C. or higher, The concentration of boron taken from the impurity diffusion layer into the titanium silicide layer is suppressed, and the low diffusion layer resistance is maintained.

[0018]

As described above, according to the present invention, after forming the refractory metal film, before or after silicidation,
Since the second impurity ion implantation is performed, a decrease in the impurity concentration of the impurity diffusion layer due to silicidation is suppressed or supplemented, and a low resistance diffusion layer is obtained. Therefore, a good ohmic contact is obtained and an increase in the parasitic resistance of the transistor is avoided.

[Brief description of drawings]

FIG. 1A is a view for explaining a first embodiment of the present invention, FIG.
It is a process order sectional view divided and shown in (b).

2A to 2C are sectional views in order of the processes, which are illustrated by dividing them into FIGS. 1A and 1B for explaining a process subsequent to the process corresponding to FIG.

FIG. 3A is a view for explaining a second embodiment of the present invention.
It is a process order sectional view divided and shown in (c).

FIG. 4 (a) for explaining a third embodiment of the present invention,
It is a process order sectional view divided and shown in (b).

5A to 5C are cross-sectional views in order of the processes, which are illustrated by dividing into (a) and (b) for explaining a conventional example.

6A to 6C are cross-sectional views in order of the processes, which are illustrated by dividing them into (a) and (b) for explaining a process subsequent to the process corresponding to FIG.

[Explanation of symbols]

 1 N-type silicon substrate 2 Field oxide film 3 Gate oxide film 4 Polysilicon film 5 Tungsten silicide film 6 Gate electrode 7 Low concentration ion implantation layer 7a Low concentration impurity diffusion layer 8 Spacer 9 Silicon oxide film 10 High concentration ion implantation layer 10a High Concentration impurity diffusion layer 11 Opening 12 Titanium film 13 Low-concentration layer 14,14a Titanium silicide layer 15 Interlayer insulating film 16 Opening 17-1, 17-2 Wiring 18, 18a Boron ion implantation layer 19, 19a Second high concentration Impurity diffusion layer 20 First boron ion implantation layer 21 Second boron ion implantation layer 22 Third high-concentration impurity diffusion layer

Claims (2)

[Claims] 1. A first step of selectively implanting first second conductivity type impurity ions into a first conductivity type region of a surface portion of a semiconductor silicon substrate and performing a first heat treatment to form an impurity diffusion layer. A step of depositing a refractory metal film on the impurity diffusion layer, a second heat treatment is performed to form a refractory metal silicide layer, and a portion of the refractory metal film that is not silicified and remains is removed. The second step, a third step of implanting second impurity ions of the second conductivity type into the impurity diffusion layer before or after the second step, and a step of performing a third heat treatment. Method for manufacturing semiconductor integrated circuit device. 2. The method for manufacturing a semiconductor integrated circuit device according to claim 1, wherein the refractory metal is at least one of titanium, cobalt, nickel, tungsten, molybdenum, tantalum and platinum.