JPH07176736A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To increase Si ions which contribute to a reaction to silicidize when a metal silicide interconnection is formed by using Si by an ion implantation operation. CONSTITUTION:A photoresist film 11 having an opening part is formed in a region, in which a metal silicide interconnection is to be formed, on a metal film 4 which can be silicized. By making use of the photoresist film 11 as a mask, silicon (Si) ions are made to impinge from an oblique direction of about 45 deg. with reference to the main face of a silicon substrate 1, and the Si ions are implanted into the metal film 4. The photoresist film 11 is removed, the metal film 4 into which the silicon ions have been implanted is then heated and treated, and the silicide interconnection having a metal silicide film 10 is formed. By adopting this method, the effective thickness of the metal film is increased, and the Si ions which contribute to a reaction to silicidize are increased.

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 device, and more particularly to a method for manufacturing a semiconductor device composed of a MOS integrated circuit.

[0002]

2. Description of the Related Art A method using metal silicide wiring has been proposed for improving the integration degree of a CMOS integrated circuit.
One example is IEEE TRANSACTIONS ON ELECTRON DEVICES, VO
L.34, NO.3, MARCH, 1987, p587. This method will be described with reference to FIG.

First, as shown in FIG. 3A, a field oxide film 2 of about 500 nm is formed on a silicon substrate 1 by using a known selective oxidation method, and then a normal MOS is formed.
According to the transistor forming process, the gate oxide film 3, the polysilicon gate electrode 4, and the sidewall oxide film 5 are formed.
To form a gate structure. Then, a predetermined impurity is introduced by using an ion implantation method to form the source / drain regions 6 of the MOS transistor.

Next, as shown in FIG. 3B, a silicidable metal (for example, Ti) 7 is formed on the entire surface to a thickness of about 50 nm, and then amorphous silicon (a-Si) is formed on the entire surface of the metal film 7. ) A layer 8 is formed to a thickness of about 100 nm.

Further, as shown in FIG. 3C, a region where a metal silicide wiring is to be formed is covered with a photoresist film 9, and the photoresist film 9 is used as a mask to form aS.
The i layer 8 is removed. Subsequently, after removing the photoresist film 9, the a-Si layer 8 to be the metal silicide wiring on the gate electrode 4 and the source / drain regions 6 is silicided by heat treatment in nitrogen at 600 ° C. for about 30 minutes. React. At this time, the upper metal film such as the field oxide film 2 which does not undergo the silicidation reaction becomes TiN,
Alternatively, Ti remains unreacted.

Next, as shown in FIG. 3D, TiN on the field oxide film 2 and unreacted Ti are removed by H ₂ S.
After removing with O ₄ + H ₂ O ₂ solution,
A low resistance metal silicide film 10 is formed by heat treatment in nitrogen for about 0 minutes.

In the method of manufacturing a semiconductor device including the metal silicide wiring described above, a step of removing the amorphous silicon (a-Si) layer 8 formed on the entire surface of the metal film 7 by selective etching using the photoresist film as a mask. To adopt. This etching is performed by RIE (Reactive Ion Et
Since this is performed by the ching method, the thickness of the metal film 7 is also reduced, and a silicide layer having a required thickness cannot be obtained. Therefore, there is a problem in that the resistance of the silicide wiring layer increases and the device characteristics are adversely affected.

Proposals have been made to solve the above problems in a method of manufacturing a semiconductor device including a metal silicide wiring. One example is injection of Japanese Patent Laid-Open No. Hei 3I.

Next, as shown in FIG. 4 (b), after removing the photoresist film 11, a heat treatment in nitrogen at 600 ° C. for about 30 minutes is performed on the upper portion of the gate electrode 4 and the source / drain regions 6 to form S for forming metal silicide wiring
The i-ion implantation region 12 is silicidized.

Subsequently, as shown in FIG. 4C, TiN on the field oxide film 2 and unreacted Ti are removed by H2.
After removing with SO4 + H2O2 solution,
A low resistance metal silicide film 10 is formed by heat treatment in nitrogen for about 0 minutes.

[0011]

In the conventional method of manufacturing a semiconductor device shown in FIG. 4, the metal silicide wiring formed on the field oxide film has a high resistance as the metal film becomes thinner as the device becomes finer. Tends to become. This is because, due to the distribution of ion-implanted Si ions in the depth direction, when the metal film becomes thin, some of the Si ions penetrate through the metal film and contribute to the silicidation. Is extremely reduced. The increase in the resistance of the wiring leads to a decrease in the operating speed of the semiconductor device, and it is necessary to prevent this.

Further, in the end region of the field oxide film and the region of the sidewall oxide film, Si ions implanted in these regions are reduced, so that the metal silicide wiring has a high resistance. In particular, in the sidewall oxide film, as shown in FIG. 5, since there is a region where Si ions are not substantially implanted, the metal silicide wiring is not formed in that region, and the silicide wiring is broken, resulting in a semiconductor device of the semiconductor device. The problem of reducing reliability arises.

The present invention has been made in order to solve the above problems, and is capable of manufacturing a semiconductor device having a metal silicide wiring having a sufficiently low resistance and high reliability. The purpose is to provide a method.

[0014]

In order to achieve the above object, a method of manufacturing a semiconductor device according to the present invention comprises a step of forming an oxide film for element isolation on a main surface of a semiconductor substrate, and a step of using the oxide film. A step of forming a gate structure composed of a gate oxide film, a polysilicon gate electrode, and a sidewall oxide film in a region to be separated, and an impurity is introduced into the main surface adjacent to the gate structure to form a source / drain. Forming a region, forming a metal film made of a silicidable metal on the entire surface including the gate structure and the source / drain regions, and forming a photoresist film having an opening at a predetermined position on the metal film. A step of forming and a step of implanting silicon ions into the metal film from an oblique direction with respect to the main surface using the photoresist film as a mask,
And a step of siliciding the metal film into which the silicon ions are implanted by heat treatment.

The silicidable metal film is made of titanium (Ti), zirconium (Zr), cobalt (Co),
It is preferable to select one or more metals from the metal group consisting of molybdenum (Mo), tungsten (W), nickel (Ni), platinum (Pt), and palladium (Pd).

It is also a preferred embodiment of the present invention to further include a step of implanting silicon ions into the metal film from a direction perpendicular to the main surface of the substrate prior to the silicidation step.

The implantation amount of silicon ions from the direction oblique to the main surface is preferably 1E10 17 cm −2 or more, and when the step of implanting silicon ions perpendicular to the main surface is adopted. The silicon ion implantation amount from the vertical direction is preferably about 1/2 of the implantation amount from the oblique direction, and the implantation amount is 5E1016c.
It is preferable to select m-2 or more.

[0018]

The present invention will be described below with reference to the drawings. 1 (a) to 1 (c) are vertical cross-sectional views of respective steps of a semiconductor device for explaining a method of manufacturing a semiconductor device according to a first embodiment of the present invention.

First, as shown in FIG. 1A, a field oxide film 2 of about 500 nm is formed on a silicon substrate 1 by using a known selective oxidation method, and then a normal MO film is formed.
According to the formation process of the S transistor, the gate oxide film 3,
A gate structure composed of the polysilicon gate electrode 4 and the sidewall oxide film 5 is formed. Further, the source / drain regions 6 of the MOS transistor are formed in the silicon substrate 1 adjacent to the gate structure by the ion implantation method. Before forming the sidewall oxide film 5, L
It is preferable to form a thin implanted diffusion layer to obtain the DD structure.

Next, as shown in FIG. 1B, after a metal (for example, Ti) 7 that can be silicidized is formed to have a film thickness of about 50 nm, a region where metal silicide wiring is not formed and A region where silicon is already present on the lower surface of the metal film is overlaid with a photoresist film 11, and with the photoresist film 11 as a mask, the main surface of the semiconductor substrate 1 is obliquely irradiated with silicon (Si) ions and implanted. A quantity of 1E10 17 cm −2 or more of Si ions is implanted into the metal film 7. At this time, it is preferable to implant Si ions while rotating the silicon substrate 1 by about 1 rps. Si
If the ion implantation amount is small, silicidation becomes insufficient and the metal silicide has a high resistance. Therefore, the implantation amount of Si ions in this oblique implantation is preferably 1E1017 cm-2 or more.

After removing the photoresist film 11, 6
By heat treatment in nitrogen at 00 ° C. for about 30 minutes, the Si ion-implanted region 12 on the gate electrode 4 and the source / drain region 6 where the metal silicide wiring is to be formed is silicidized.

Subsequently, as shown in FIG. 1C, TiN on the field oxide film 2 and unreacted Ti are removed by H2.
Remove with SO4 + H2O2 solution. Then 800 ° C
1C by finally forming the low-resistance metal silicide film 10 by heat treatment in nitrogen for about 30 minutes.
The structure shown in is obtained. .

In the method of manufacturing the semiconductor device according to the first embodiment, as shown in FIG. 6, there is a possibility that a region where the implantation amount of Si ions is reduced may be formed due to the step difference of the photoresist film and the gate electrode. . This decrease is due to the characteristics of the device,
If a problem arises, the second embodiment described below is used. In the second embodiment, sufficient Si can be supplied to form a stable metal silicide wiring in the region where the implantation amount of Si generated in the first embodiment is reduced.

2 (a) to 2 (d) are vertical cross-sectional views of the respective steps of the semiconductor device for explaining the method of manufacturing the semiconductor device of the second embodiment.

First, as shown in FIG. 2A, a field oxide film 2 of about 500 nm is formed on the main surface of the silicon substrate 1 by using a known selective oxidation method, and then a normal MO film is formed.
According to the formation process of the S transistor, the gate oxide film 3,
A gate structure composed of the polysilicon gate electrode 4 and the sidewall oxide film 5 is formed. Furthermore, a MOS is formed in the silicon substrate 1 adjacent to the gate structure by using the ion implantation method.
The source / drain regions 6 of the transistor are formed.

Next, as shown in FIG. 2B, after a metal (for example, Ti) 7 that can be silicidized is formed to have a film thickness of about 50 nm, a region where a metal silicide wiring is not formed and A region where silicon is sufficiently present on the lower surface of the metal film is covered with the photoresist film 11. Using the photoresist film 11 as a mask, the main surface of the semiconductor substrate 1 is irradiated with Si ions from an oblique direction, and 1E10 1
Si ions of 7 cm-2 or more are implanted into the metal film 7. The implantation angle is preferably about 45 ° with respect to the silicon substrate 1. Further, at this time, it is preferable to obliquely implant Si ions while rotating the silicon substrate by about 1 rps.

Subsequently, as shown in FIG. 2 (c), Si ions are radiated from the direction perpendicular to the main surface of the silicon substrate 1, and the implantation amount is about half of the oblique implantation (5E10 16 cm −2).
Si ions are implanted into the metal film 7 so as to be the above.

After removing the photoresist film 11, 6
By heat treatment in nitrogen at 00 ° C. for about 30 minutes, the Si ion-implanted region 12 on the gate electrode 4 and the source / drain region 6 where the metal silicide wiring is to be formed is silicidized.

Next, as shown in FIG. 2 (d), TiN on the field oxide film 2 and unreacted Ti are removed by H2SO4.
After removing with + H2O2 solution, a low resistance metal silicide film 10 is formed by heat treatment in nitrogen at 800 ° C. for about 30 minutes.

In the method of manufacturing a semiconductor device of each of the above-mentioned embodiments, since the ion implantation of Si ions into the silicidable metal film 7 is carried out in an oblique direction with respect to the main surface of the silicon substrate 1, the ion implantation is performed. Since the effective metal film thickness in the implantation direction can be increased, the Si ions in the metal film contributing to the silicide reaction can be effectively increased.

Further, since there is no region where Si ions are not substantially implanted as shown in FIG. 5, there is a possibility that the metal silicide wiring is not formed and the metal silicide wiring is disconnected. Absent.

Although the present invention has been described based on its preferred embodiments, the present invention can be modified and changed in various ways from the aspects of the above-described embodiments, and various modifications and changes can be made from the method of the above-described embodiments. The modified method is also included in the semiconductor device manufacturing method of the present invention.

[0033]

As described above, according to the method of manufacturing a semiconductor device of the present invention, by implanting Si ions into the metal film from an oblique direction with respect to the main surface of the substrate, the metal film with respect to the Si ions can be formed. Since the effective film thickness can be increased, a sufficient silicidation reaction is performed by Si ions, so that a semiconductor device having a silicide wiring with a sufficiently low resistance value and without fear of disconnection can be manufactured. There is a remarkable effect.

[Brief description of drawings]

1A to 1C are vertical cross-sectional views of a semiconductor device for each process step for explaining a method according to a first embodiment of the present invention.

FIGS. 2A to 2D are vertical cross-sectional views of the semiconductor device at each process step for explaining the method of the second embodiment of the present invention. FIGS.

FIG. 3 is a vertical cross-sectional view of the semiconductor device at each process step in the conventional semiconductor device manufacturing method.

FIG. 4 is a vertical cross-sectional view of the semiconductor device for each process step in another conventional method for manufacturing a semiconductor device.

FIG. 5 is a vertical cross-sectional view of a semiconductor device in one process step for explaining problems in the conventional method.

FIG. 6 is a vertical cross section of a semiconductor device for explaining the effect of the second embodiment of the present invention.

[Explanation of symbols]

 1 Silicon Substrate 2 Field Oxide Film 3 Gate Oxide Film 4 Polysilicon Gate Electrode 5 Sidewall Oxide Film 6 Source / Drain Region 7 Sildable Metal Film 8 Amorphous Silicon Layer 9, 11 Photoresist Film 10 Metal Silicide Film 12 Si Ion Region in which 13 Si ions are not implanted 14 Region in which the implantation amount of 14 Si ions is reduced

Claims (5)

[Claims] 1. A step of forming an oxide film for device isolation on a main surface of a semiconductor substrate, a gate oxide film, a polysilicon gate electrode in a region separated by the oxide film, and
Including a step of forming a gate structure formed of a sidewall oxide film, a step of introducing an impurity into the main surface adjacent to the gate structure to form a source / drain region, and the step of including the gate structure and the source / drain region Forming a metal film made of a metal capable of silicidation on the entire surface, forming a photoresist film having an opening at a predetermined position on the metal film, and using the photoresist film as a mask on the main surface On the other hand, a method of manufacturing a semiconductor device, comprising: a step of implanting silicon ions into the metal film from an oblique direction; and a step of silicidizing at least the metal film into which the silicon ions are implanted by heat treatment. 2. The silicidable metal is one or more metals selected from the group consisting of titanium, zirconium, cobalt, molybdenum, tungsten, nickel, platinum, and palladium. 1. The method for manufacturing a semiconductor device according to 1. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the implantation amount of silicon ions implanted into the metal film from the oblique direction is 1E10 ¹⁷ cm ⁻² or more. 4. The semiconductor according to claim 1, further comprising a step of implanting silicon ions into the metal film from a direction perpendicular to the main surface prior to the step of silicidation. Device manufacturing method. 5. The method of manufacturing a semiconductor device according to claim 4, wherein the implantation amount of silicon ions implanted into the metal film in the vertical direction is 5E10 ¹⁶ cm ⁻² or more.