JP2917348B2 - Method of manufacturing MIS type semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor device in which a refractory metal silicide is selectively formed on a silicon surface.

[Prior Art] In a conventional method of manufacturing a semiconductor device having a structure in which titanium silicide is selectively formed on the surface of silicon,
In particular, in a method of manufacturing a semiconductor device in which polycrystalline silicon is used as a gate electrode and titanium silicide is formed on the surface of the polycrystalline silicon of the gate electrode, impurities are contained in the polycrystalline silicon in order to impart conductivity to the polycrystalline silicon. However, when the phosphorus concentration is increased and becomes supersaturated in the polycrystalline silicon, the reaction between titanium and silicon is suppressed and it becomes difficult to form silicide. The concentration of phosphorus diffused into the polycrystalline silicon was reduced.

[Problem and Object to be Solved by the Invention] However, when a complementary MIS transistor is formed by using the above-described conventional manufacturing method, the phosphorus concentration in the polycrystalline silicon as the gate electrode is low and the P channel side is low. The boron, which is a P-type impurity implanted when an impurity diffusion layer serving as a source / drain is formed, is also implanted into a gate electrode, thereby reducing the number of electrons as carriers for generating N-type impurity phosphorus. However, there has been a problem that the resistance of the gate electrode is increased and a threshold voltage which is a switching characteristic of the transistor is changed. In addition, since the carrier concentration in the gate electrode is low, the contact resistance between titanium silicide formed on the polycrystalline silicon surface and the polycrystalline silicon increases, which may cause a malfunction of the semiconductor device and prevent the semiconductor device from operating at high speed. Had problems.

Therefore, the present invention is intended to solve such a problem, and an object of the present invention is to form a refractory metal silicide in a self-aligned manner on the surface of polycrystalline silicon as a gate electrode, and at the same time, to reduce the wiring resistance of the gate electrode. It is an object of the present invention to provide a method of manufacturing a semiconductor device in which the increase in the threshold voltage of the transistor, the change in the threshold voltage of the transistor, and the increase in the contact resistance between the refractory metal silicide and the polycrystalline silicon are suppressed.

[MEANS FOR SOLVING THE PROBLEMS] A method for manufacturing an MIS type semiconductor device according to the present invention is a method for manufacturing a MIS type semiconductor device in which silicide of a high melting point metal is formed on an exposed silicon surface in a self-aligned manner. Forming a polycrystalline silicon film via a gate insulating film, and diffusing the impurity concentration of the first conductivity type into the polycrystalline silicon film by at least one order of magnitude higher than the impurity concentration of the second conductivity type which is later ion-implanted. A step of implanting argon ions into the polycrystalline silicon film in which the impurities of the first conductivity type are diffused to make the vicinity of the surface of the polycrystalline silicon film amorphous, Processing into a gate electrode and a wiring by photolithography and etching, and depositing an insulating film on the entire surface of the semiconductor substrate; Forming a side wall of the insulating film on the side surface of the gate electrode by etching; forming a refractory metal film on the entire surface of the semiconductor substrate; heating the semiconductor substrate on which the refractory metal film is formed; Changing the refractory metal on the silicon substrate surface and the gate electrode exposed by the process to a silicide of the refractory metal, a compound of the refractory metal other than the refractory metal silicide, and the unreacted refractory metal A method for selectively removing a metal, comprising: a step of selectively removing a metal.

Further, in the method for manufacturing an MIS type semiconductor device according to the present invention, titanium is used as the high melting point metal.

Embodiments FIGS. 1A to 1G show an embodiment of the present invention, and are cross-sectional views of a semiconductor device illustrating a method of manufacturing a semiconductor device of the present invention step by step. Hereinafter, a method for manufacturing a semiconductor device according to the present invention will be described as an embodiment with reference to FIG.

As shown in FIG. 1A, a polycrystalline silicon film 3 is formed on a silicon substrate 1 of a semiconductor device with a gate insulating film 2 interposed therebetween. In this embodiment, the thickness of the first polycrystalline silicon film is 4000 °. The polycrystalline silicon film has almost no conductivity when no impurities are contained. Therefore, in this embodiment, as shown in FIG. 1 (b), the semiconductor substrate is heated at 900 ° C. in an atmosphere of phosphorus oxychloride to thermally diffuse phosphorus as an impurity in the polycrystalline silicon film, thereby obtaining an N-type semiconductor substrate. Was made conductive as a semiconductor. The concentration of phosphorus implanted by thermal diffusion is higher than the concentration of boron implanted for forming the impurity diffusion layer of the source / drain of the P channel by one digit or more. Titanium hardly forms silicide for polycrystalline silicon containing phosphorus at such a high concentration. Next, as shown in FIG. 1C, impurity ions are implanted into the polycrystalline silicon film 1 in which phosphorus is diffused. In this embodiment, argon ions are implanted as an example. The implanted argon ions destroy the crystal growth of the polycrystalline silicon and become amorphous, resulting in an amorphous silicon layer 4 near the surface of the polycrystalline silicon. Amorphous silicon tends to react with titanium to become titanium silicide. By removing portions of the polycrystalline silicon film and the amorphous silicon layer other than the gate electrode and the wiring by the photolithography technique and the etching technique, the gate electrode and the wiring are formed on the semiconductor substrate as shown in FIG. Next, an insulating film is formed on the entire surface of the semiconductor substrate. As an example, this insulating film was formed by a chemical vapor deposition method at a temperature of about 400 ° C. and was made of an insulating film containing SiO 2 as a main component and having a thickness of 5000 °. This insulating film is entirely anisotropically etched in a plasma of a chlorofluorocarbon gas, leaving only the side surfaces of the gate electrode and the wiring, and removing the other portions,
As shown in FIG. 1E, a side wall 5 made of an insulating film is formed on the side surfaces of the gate electrode and the wiring. Thereafter, as shown in FIG. 1 (f), a titanium metal film 6 is formed on the entire surface of the semiconductor substrate. In this embodiment, the thickness of the titanium metal film is 500 °. By subjecting the semiconductor substrate to heat treatment, silicon and titanium react with each other to selectively change titanium in a portion in contact with silicon to titanium silicide. As an embodiment of the present invention, a short-time annealing by light irradiation with a halogen lamp in nitrogen gas is performed.
Heat the semiconductor substrate surface to 750 ° C. for 30 seconds. The portion of the silicon layer on the surface of the polycrystalline silicon which has been made amorphous by this heating and the silicon of the semiconductor substrate where the silicon surface is in contact with titanium react to become titanium silicide. Most of titanium on the sidewall insulating film and the element isolation insulating film reacts with nitrogen to form titanium nitride. Although some titanium remains, titanium compounds other than titanium silicide can be dissolved in a mixed solution of aqueous ammonia and aqueous hydrogen peroxide. In this embodiment, the titanium metal and the titanium compound on the sidewalls and on the element isolation insulating film are removed by using this method, leaving only the titanium silicide, thereby removing the titanium metal and the titanium compound on the exposed silicon substrate as shown in FIG. In addition, titanium silicide 7 was selectively formed on the gate electrode and the polycrystalline silicon serving as the wiring.

According to the method of manufacturing a semiconductor device of the present invention described above as an embodiment, the silicon layer 4 made amorphous by ion implantation of impurity ions easily reacts with titanium and easily becomes titanium silicide. Since phosphorus contains a large amount of phosphorus as an impurity, the reaction with titanium is suppressed. That is, since the amorphous silicon layer 4 can be entirely made of titanium silicide 7 and the polycrystalline silicon film 3 remains as it is, titanium silicide can be formed on the gate electrode and the wiring with good controllability. Furthermore, since the titanium silicide formed on the gate electrode and the wiring is in contact with polycrystalline silicon containing high concentration of phosphorus, the contact resistance between titanium silicide and polycrystalline silicon, which was a problem of the prior art, has been reduced. .

Further, as described in the above embodiment, since the polycrystalline silicon contains phosphorus at a high concentration, the phosphorus concentration hardly changes even by the implantation and diffusion of boron which is an impurity for forming the source / drain of the P-channel. Therefore, the resistance of the gate electrode on the P-channel side does not increase and the threshold voltage of the transistor does not change.

In the above embodiments, argon ions are described as an example of the second impurity which breaks the crystallinity in the vicinity of the surface of polycrystalline silicon and becomes amorphous, but other ions such as phosphorus, arsenic, boron, etc. Is not different from the operation described in the above embodiment, and is not different from the method of manufacturing a semiconductor device of the present invention. In this embodiment, titanium is used as the high melting point metal and phosphorus is used as the first impurity, but the present invention is not limited to this.

[Effects of the Invention] As described above, the present invention has the following effects.

(1) Refractory metal silicide can be formed with good controllability on polycrystalline silicon containing a high concentration of impurities as a gate electrode.

(2) The contact resistance between polycrystalline silicon, which is a gate electrode and a wiring, and high-melting-point metal silicide could be reduced. This is very advantageous in high-speed operation of the semiconductor device.

(3) The conventional technique of forming a refractory metal silicide on the silicon surface in a self-aligned manner, which is a problem in that the resistance of the gate electrode on the P-channel side is increased, and the threshold voltage of the P-channel transistor is changed. Problem solved.

[Brief description of the drawings]

1 (a) to 1 (g) are cross-sectional views of a semiconductor device illustrating a method of manufacturing a semiconductor device according to the present invention step by step. DESCRIPTION OF SYMBOLS 1 ... Silicon semiconductor substrate 2 ... Gate insulating film 3 ... Polycrystalline silicon film 4 ... Amorphized silicon layer 5 ... Side wall 6 ... Refractory metal 7 ... Refractory metal silicide

Claims (2)

(57) [Claims] 1. A method of manufacturing a MIS type semiconductor device in which a refractory metal silicide is formed in a self-aligned manner on an exposed silicon surface, comprising: forming a polycrystalline silicon film on a semiconductor substrate via a gate insulating film; Diffusing the impurity concentration of the first conductivity type into the polycrystalline silicon film by one digit or more than the impurity concentration of the second conductivity type which is later ion-implanted; and diffusing the first conductivity type impurity. A step of amorphizing the vicinity of the surface of the polycrystalline silicon film by implanting argon ions into the polycrystalline silicon film; and a step of processing the polycrystalline silicon film into a gate electrode and a wiring by photolithography and etching. Depositing an insulating film on the entire surface of the semiconductor substrate, and etching the insulating film to form the insulating film on the side surface of the gate electrode. A step of forming a sidewall; a step of forming a refractory metal film over the entire surface of the semiconductor substrate; and a step of heat-treating the semiconductor substrate on which the refractory metal film is formed, on the silicon substrate surface and on the gate electrode which are exposed. Converting the refractory metal to a refractory metal silicide; and selectively removing the refractory metal compound other than the refractory metal silicide, and the unreacted refractory metal. A method for manufacturing a MIS type semiconductor device, comprising: 2. The method according to claim 1, wherein titanium is used as said refractory metal.