JPH0265128A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a metallic silicide film in self alignment on a projection and on a substrate on both sides of it by forming the inversely tapered projection on the semiconductor substrate, and forming a metallic film on the whole face of the substrate, and injecting energy beams into the surface so as to silicify it. CONSTITUTION:A field insulating film 2 is selectively formed on the surface of a semiconductor substrate 1 such as P type Si, etc. A gate insulating film 3 is formed on the surface of an active region. After forming a polycrystalline Si film where impurity is doped into the whole face, the Si film and the insulating film 3 are etched and patterned so as to form an inversely tapered gate electrode 4. With the electrode 4 as a mask, the ions of n-type impurity are implanted so as to form n-type source region 5 and drain region 6. next, the metal such as Ti, Co, Ni, or the like is deposited vertically on the surface so as to form a metallic film 7. Next, a laser beam B is applied vertically to the surface so as to form metallic silicide films 8a-8c only on the gate electrode 4 and the regions 5 and 6 separately from each other in self alignment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a technique effective for selectively forming a metal silicide film on a semiconductor.

[Summary of the Invention] The present invention includes a step of forming an inversely tapered convex portion on a semiconductor substrate, a step of forming a metal film on the entire surface of the semiconductor substrate including the convex portion, and a step of forming a metal film on the entire surface of the semiconductor substrate including the convex portion. and siliciding the metal film by irradiating the semiconductor substrate with an energy beam from a substantially perpendicular direction. As a result, metal silicide films can be formed on the protrusion and the semiconductor substrate on both sides of the protrusion in a self-aligned manner, separated from each other, without forming side walls made of an insulator on the side surfaces of the protrusion.

[Conventional technology]

S A L I C D E (Self-alig
The ned5ilicide technology is a technology in which a metal silicide film is formed on a diffusion layer or gate electrode in a self-aligned manner to reduce the sheet resistance of the diffusion layer or gate electrode.

Conventionally, MO3LSI using this 5ALICIDE,
For example, it has been manufactured by a method as shown in FIGS. 3A to 3B. That is, as shown in FIG. 3A, first, a semiconductor substrate 1, such as a p-type silicon (Si) substrate, is
After selectively forming a field insulating film 102 on the surface of 01 to perform isolation between elements, this field insulating film 102
A gate insulating film 103 is formed on the surface of the active region surrounded by.

Next, after forming a polycrystalline Si film doped with impurities, for example, on the entire surface, these polycrystalline Si films and the gate insulating film 1
03 is patterned into a predetermined shape by etching. As a result, gate electrode 104 is formed. Thereafter, using this gate electrode 104 as a mask, the semiconductor substrate 1
By ion-implanting n-type impurities at a low concentration into 01, for example, the n-type source region 105 and drain region 1
06 is formed in a self-aligned manner with respect to the gate electrode 104.

Next, an insulating film such as a 5iOz film is formed on the entire surface by, for example, CVD, and then this insulating film is anisotropically etched in a direction perpendicular to the substrate surface by, for example, reactive ion etching (RIE). As shown in FIG. 3B, side walls (side wall spacers) 107 made of an insulating material are formed.

Next, as shown in FIG. 3C, the entire surface is made of, for example, titanium (Tl).
) forming a film 108;

Next, the Ti film 108 is reacted with the gate electrode 104, the source region 105, and the drain region 106, which are in direct contact with the Ti film 108, by performing annealing at a temperature of, for example, about SO'C. As a result, the Ti film 108 on the gate electrode 104, source region 105, and drain region 106 is silicided. As a result, as shown in the third diagram, the gate electrode 104
, titanium silicide (TiSiz) films 109a and 1 are formed on the source region 105 and drain region 106, respectively.
09b and 109C are formed.

Thereafter, the unreacted Ti film 108 is removed by etching to obtain the state shown in FIG. 3E.

[Problem to be solved by the invention]

In the conventional MO3LSI manufacturing method described above, by forming the sidewalls 107 made of an insulator on both sides of the gate electrode 104, the gate electrode 10 made of a TiSi2 film is formed.
4 and the source region 105 and drain region 106 are prevented from shorting. However, in order to form this sidewall 107, two steps of forming an insulating film and etching this insulating film are required as described above, making the LSI manufacturing process complicated.

Therefore, an object of the present invention is to separate metal silicide films from each other on the protrusion and the semiconductor substrate on both sides of the protrusion, without forming sidewalls made of an insulator on the side surfaces of the protrusion such as the gate electrode, thereby forming a self-aligned structure. An object of the present invention is to provide a method for manufacturing a semiconductor device that can be formed in a manner similar to that described above.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a semiconductor substrate (1)
a step of forming an inverted tapered convex portion (4) on the convex portion (4);
4) and the step of forming a metal film (7) on the entire surface of the semiconductor substrate (1) including
) to silicide the metal film (7).

The convex portion (4) may be formed by a gate electrode formed on the semiconductor substrate (1) or by selectively etching the semiconductor substrate (1).

As the energy beam, a laser beam, an electron beam, an ion beam, etc. can be used.

[Effect]

According to the above-mentioned means, since the convex portion (4) has a reverse tapered shape, the metal film ( 7
) is not irradiated with this energy beam (B). The portion of the metal film (7) that is not irradiated with this energy beam (B) is not silicided, and therefore no metal silicide film is formed in this portion. As a result, the convex portion (4
) The metal silicide films (8a, 8b, 8C) are separated from each other and self-aligned on the convex portion (4) and the semiconductor device (1) on both sides thereof without forming a side wall made of an insulator on the side surface of the convex portion (4). It can be formed as follows.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. This example uses MO using 5ALICIDE.
This is an example in which the present invention is applied to the manufacture of 3LSI.

FIGS. 1A to 1E show MO3 according to an embodiment of the present invention.
A method for manufacturing an LSI will be shown in order of steps.

In this embodiment, as shown in FIG. 1A, first, for example, S is applied to the surface of a semiconductor substrate 1 such as a p-type St substrate.
After selectively forming a field insulating film 2 such as an iO□ film by, for example, thermal oxidation to provide isolation between elements, for example, StO□ is formed on the surface of the active region surrounded by this field insulating film 2 by, for example, thermal oxidation. A gate insulating film 3 like a film is formed. Next, a polycrystalline Si film doped with impurities is formed over the entire surface by, for example, the CVD method, and then the polycrystalline Si film and the gate insulating film 3 are patterned into a predetermined shape by etching. As a result, gate electrode 4 is formed. At this time, select the cross-sectional shape of the resist used as an etching mask and the etching conditions.
The cross-sectional shape of the gate electrode 4 is made to have an inversely tapered shape. Thereafter, using the gate electrode 4 as a mask, n-type impurities such as arsenic (As) and phosphorus (P) are ion-implanted into the semiconductor substrate 1 at a low concentration. As a result, for example, an n-type source region 5 and drain region 6 are formed in a self-aligned manner with respect to the gate electrode 4. These gate electrode 4, source region 5, and drain region 6 constitute an n-channel MOS FET.

Next, as shown in FIG. 1B, T is applied to the entire surface by, for example, vapor deposition.
i1 A metal film 7 of cobalt (co), nickel (Ni), etc. is formed. In this case, in order to prevent the metal film 7 from being formed on both sides of the gate electrode 4, this vapor deposition is preferably performed in a direction perpendicular to the substrate surface. As mentioned above, the gate electrode 4 has a reverse tapered shape, so when vapor deposition is performed from a direction perpendicular to the substrate surface, the side surface of the gate electrode 4 is shaped like this when viewed in the vapor deposition direction. The metal film 7 is shadowed by the upper surface of the gate electrode 4, so that the metal film 7 is not formed on the side surfaces of the gate electrode 4. Next, in this state, the entire surface of the substrate is irradiated with, for example, a laser beam B at a predetermined irradiation energy density from a direction perpendicular to the substrate surface.

As this laser beam B, for example, a pulsed laser beam (wavelength 308
nm) can be used. This laser beam B
By this irradiation, the surface layers of the metal film 7, gate electrode 4, source region 5, and drain region 6 are locally heated to a high temperature.

As a result, the metal film 7 and the gate electrode 4, source region 5, and drain region 6 that are in direct contact with the metal film 7 react, and the metal on these gate electrode 4, source region 5, and drain region 6 reacts. The film 7 is silicided. In this case, since the gate electrode 4 has a reverse tapered shape, the portion of the upper surface of the gate electrode 4 that is in the shadow when viewed from the irradiation direction of the laser beam B, that is, the portion near the bottom of the gate electrode 4. Metal film 7 is not silicided. As a result, as shown in FIG.
Metal silicide films 8a, 8b, and 8c such as i2 films are formed separated from each other in a self-aligned manner. These metal silicide films 8a, 8b, and 8c can reduce the sheet resistance of the gate electrode 4, source region 6, and drain region 7. In particular, a film of Ti5iz, which has the lowest resistance among metal silicides, is used as the metal silicide film 8a.
.

When used as 8b or 8c, the effect of reducing sheet resistance is large. As a result, even if the source region 6 and drain region 7 are doped at low impurity concentrations as described above, the operating speed of the FET does not decrease.

Next, the unreacted metal film 7 is removed by etching to obtain the state shown in the first diagram.

Next, as shown in Figure 1, for example, a phosphosilicate glass (PSG) film or SiO
After forming the glabellar insulating film 9 like a film, a predetermined portion of the glabellar insulating film 9 is removed by etching to form a contact hole 9.
a, 9b, and 9C are formed. Next, for example, an At film is formed on the entire surface by sputtering or vapor deposition, and then this At film is patterned into a predetermined shape by etching to form wiring lines 10, 11, for gate, source, and drain, respectively.
12 is formed, thereby completing the target MO3LS1.

As described above, according to this embodiment, after forming the reverse tapered gate electrode 4, the metal film 7 is formed on the entire surface, and then the laser beam B is irradiated from the direction perpendicular to the substrate surface. Since this metal film 7 is silicided, metal silicide films 8a, 8b, and 8c can be formed on the gate electrode 4, source region 5, and drain region 6 in a self-aligned manner, separated from each other. . This can prevent short circuits between the gate electrode 4 and the source region 5 and drain region 6 due to the metal silicide film. Moreover, in this case, there is no need to form side walls made of an insulator on the side surfaces of the gate electrode 4 as in the conventional case.
The two steps of forming an insulating film and subsequent etching, which are necessary for forming this sidewall, are no longer necessary, and therefore MO3
The LSI manufacturing process can be simplified. Thereby, it is possible to reduce the manufacturing cost of MO3LSI.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications are possible based on the technical idea of the present invention.

For example, in the above embodiment, the entire surface is irradiated with the laser beam B, but the gate electrode 4, the source region 5, and the drain region 6 may be selectively irradiated with the laser beam B. Further, in the above embodiment, the source region 5 and the drain region 6 have a low impurity concentration, but it is not necessary to have such a low impurity concentration, and the impurity concentration may be higher if necessary. . Furthermore, in the above-described embodiment, since the ion implantation for forming the source region 5 and drain region 6 is performed in a direction perpendicular to the substrate surface, these source region 5 and drain region 6 are connected to the gate electrode. 4, but this can be prevented by performing the above-mentioned ion implantation from a direction oblique to the substrate surface.

In addition, in the above-mentioned embodiment, the present invention is applied to MO3LST.
Although the present invention has been described for the case where it is applied to, for example, the present invention can be applied to the manufacture of semiconductor integrated circuit devices other than MO3LSI, such as bipolar LSI and bipolar CMO3LSI, as well as other semiconductor devices.

Figure 2 shows a permable base transistor (PBT)
An example in which the present invention is applied to the production of

As shown in FIG. 2, in this permable base transistor, an inversely tapered convex portion 21a is formed on a semiconductor substrate 21, such as an n-type Si substrate.

Reference numeral 22 indicates a cathode region made of, for example, an n-type semiconductor region. Metal silicide films 23a and 23b, such as NtSiz films, are respectively formed on the convex portion 21a and the portions (grid regions) of the semiconductor substrate 21 on both sides thereof.
is formed. Here, this metal silicide film 23
a is in ohmic contact with the cathode region 22. Further, the metal silicide film 23b forms a grid,
A Schottky junction is formed with the semiconductor substrate 21. Reference numeral 24 indicates a glabellar insulating film, and a cathode electrode 25 and a grid electrode 26 made of, for example, AI are formed through contact holes 24a and 24b formed in this glabellar insulating film 24, respectively. On the other hand, on the back surface of the semiconductor substrate 21, an anode region 27 made of, for example, an n''' type semiconductor region, a metal silicide film 28 such as TiSi, [9], and an anode electrode 29 made of, for example, AI are formed.

In this example, since the convex portion 21a has a reverse tapered shape, metal silicide films 23a, 23b are formed on the convex portion 21a and the semiconductor substrate 21 on both sides thereof.
can be formed in a self-aligned manner separated from each other, thereby preventing short circuits between the grid and the cathode due to the metal silicide film.

In region, 7: Metal film, 8a, 8b, 8C: Metal silicide film, B: Laser beam.

[Effects of the Invention] As described above, according to the present invention, the metal film in the shadow part of the upper surface of the convex part when viewed from the irradiation direction of the energy beam is not silicided, so that an insulating material is formed on the side surface of the convex part. The metal silicide films can be formed in a self-aligned manner, separated from each other, on the convex portion and the semiconductor substrate on both sides thereof, without forming side walls consisting of the convex portion and the semiconductor substrate on both sides thereof.

[Brief explanation of the drawing]

FIG. 1A to FIG. 1E are MO3Ls according to an embodiment of the present invention.
2 is a cross-sectional view showing a modification of the present invention, and FIGS. 3A to 3E are cross-sectional views showing a method for manufacturing SI in the order of steps.
FIG. 3 is a cross-sectional view showing a method for manufacturing O3LSI.

Claims (1)

[Claims] A step of forming an inverted tapered convex portion on a semiconductor substrate, a step of forming a metal film on the entire surface of the semiconductor substrate including the convex portion, and a step substantially perpendicular to the surface of the semiconductor substrate. A method of manufacturing a semiconductor device, comprising the step of siliciding the metal film by irradiating the semiconductor substrate with an energy beam from a certain direction.