JP3251030B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of forming a high melting point metal on a noble metal silicide film by CVD.
The present invention relates to a method for manufacturing a semiconductor device including a step of selectively growing by a method.

[0002]

2. Description of the Related Art For speeding up and miniaturizing a semiconductor device, as shown in a schematic sectional view of FIG. 4, a diffusion layer 12 formed on the surface of a silicon substrate 1 or a multi-layer formed on the silicon substrate 1 is formed. 2. Description of the Related Art A silicide film is formed on the surface of a crystalline silicon film to reduce resistance. Further, silicidation of the surface of the silicon substrate 1 has an advantage that the connection resistance with the metal wiring can be reduced. As this silicide film, a noble metal silicide film such as a platinum silicide film 4b or a palladium silicide film is often used. The opening of the silicon oxide film 2 reaching the platinum silicide film 4b becomes finer and deeper due to the miniaturization of the semiconductor device.
And the like are selectively grown by a CVD method and embedded therein.

In order to selectively grow a high melting point metal on a noble metal silicide film, it is necessary to remove a natural oxide film formed on the surface of the noble metal silicide film. As a method of removing the natural oxide film, etching with an aqueous solution containing hydrogen fluoride is often performed, but this method alone cannot completely remove the natural oxide film on the surface of the noble metal silicide film. As shown in FIG. 4, the refractory metal is not uniformly grown on the noble metal silicide film and becomes granular. FIG. 4 schematically shows a growth state of tungsten 6d by selective growth by a CVD method when a platinum silicide film 4b is used as a noble metal silicide film and tungsten 6d is used as a high melting point metal.

In order to solve this problem, after etching with an aqueous solution containing hydrogen fluoride, and before selective growth of a refractory metal, sputtering etching with argon is performed in the same vacuum apparatus to completely eliminate the noble metal. A method of removing a natural oxide film on a silicide film and performing a heat treatment at 500 ° C. for about 4 hours to remove damage caused by a sputtering etch is disclosed in Journal of Applied Physics Vol. 67, No. 2 issued in 1990. ,
Pages 1055-1061 (Journal of Ap
Plied Physics Vol. 67, no.
2, pp 1055-1061, 1990).

[0005]

However, in the method described above, the silicon oxide film other than the noble metal silicide film is damaged by the sputtering etching with argon, and the damage cannot be sufficiently recovered by the subsequent heat treatment. In addition, the refractory metal grows on the silicon oxide film, making selective growth difficult.

Further, the reason why selective growth becomes difficult is as follows.
There is a problem that the noble metal silicide is re-adhered to the surface of the silicon oxide film due to the argon sputtering etch.

Further, even if selective growth becomes possible, there is a problem that the process becomes complicated and it takes time, resulting in poor work efficiency.

[0008]

According to a method of manufacturing a semiconductor device of the present invention, a platinum silicide film or a palladium silicide film is selectively formed on a silicon layer surface, an insulating film is formed, and the platinum silicide film or the palladium silicide film is formed. forming an opening reaching the film in the insulating film, CF ₄
Removing the natural oxide film on the surface of the platinum silicide film or palladium silicide film at the bottom of the opening by performing a surface treatment with plasma; and moving to a high melting point metal growth chamber in the same vacuum, Selectively growing a refractory metal on the surface of the silicide film or the palladium silicide film, and filling the opening with the refractory metal.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a sectional view in the order of steps for explaining a first embodiment of the present invention.

First, a silicon oxide film 2 is formed on a silicon substrate 1, an opening is formed in a predetermined position of the silicon oxide film 2, and, for example, a polycrystalline silicon film 3 doped with arsenic (for example, an emitter for a bipolar transistor). The silicon oxide film 5 is deposited on the entire surface by covering the opening, and an opening reaching the polycrystalline silicon film 3 is provided.
After forming a platinum film on the entire surface, heat treatment is performed. Due to this heat treatment, at the opening provided in the silicon oxide film 5,
Platinum silicide film 4a only on the surface of polycrystalline silicon film 3
Is formed. At the same time, a diffusion layer 12 is formed on the surface of the silicon substrate 1 in a self-aligned manner with the opening provided in the silicon oxide film 2. Thereafter, the unreacted platinum film is removed by etching [FIG. 1 (a)].

Next, a dry etching (for example, a pressure of several mTorr, a power of about 100 to 500 W) using CF4 gas is used to convert the thickness of the silicon oxide film to 2 to 20.
Etch about nm. Thereafter, the substrate is moved to a tungsten growth chamber in the same vacuum, and tungsten 20a having a thickness of about 20 to 100 nm is deposited on the platinum silicide film 4a by a low-pressure CVD method using a silane reduction method using WF ₆ gas and SiH ₄ gas. Selective formation [FIG.
(B)].

Next, an aluminum / silicon alloy film 7 is formed by sputtering, and is patterned into a desired shape to form a wiring [FIG. 1 (c)].

FIG. 2 is a schematic sectional view for explaining the structure of the present invention. A diffusion layer 12 and a platinum silicide film 4b are formed on the surface of the silicon substrate 1 in a self-aligned manner with respect to the opening formed in the silicon oxide film 3 on the silicon substrate 1, and then dry-etched using CF ₄ gas. Pretreatment is performed, and tungsten 6b is deposited by a CVD method. At this time, the tungsten 6b does not grow into a shape like the tungsten 6d as shown in FIG. 4, but grows into a good shape as shown in FIG. This is because the native oxide film on the platinum silicide film 4b is etched by the CF ₄ plasma, and the platinum silicide is completely exposed.
Further, the silicon oxide film 2 selectivity is good reason tungsten 6b does not grow on, since it is effective in a small amount of etching at relatively low power, not damaged in the silicon oxide film 2, CF ₄ In this case, only the natural oxide film and the silicon oxide film are etched, and the platinum silicide does not adhere to the silicon oxide film 2 and the like, and the surface of the silicon oxide film 2 is in a clean state.

FIG. 3 is a sectional view in the order of steps for explaining a second embodiment of the present invention. First, a silicon oxide film 8 is formed on the surface of the silicon substrate 1 by selective oxidation, and a diffusion layer 12 is formed on the surface of the silicon substrate 1. A palladium film is formed on the entire surface, heat treatment for stopping the silicidation reaction is performed, and the unreacted palladium film is removed by etching to form a palladium silicide film 9 in a self-aligned manner on the surface. Subsequently, an BPSG film 10 is deposited on the entire surface, and an opening reaching the palladium silicide film 9 is formed in the BPSG film 10 by, for example, dry etching with CF ₄ gas using a photoresist film (not shown) as a mask. Subsequently, the photoresist film is removed by, for example, O ₂ plasma [FIG. 3A].

Next, a silicon oxide film 1 of several tens nm is formed on the entire surface.
In order to lower the connection resistance at the opening, ions of the same conductivity type as the diffusion layer 12 are implanted, and a heat treatment at 800 ° C. to 1000 ° C. for activation is performed to form the diffusion layer 13. . The silicon oxide film 11 prevents boron or phosphorus from diffusing from the BPSG film 10 into the palladium silicide film 9 in the opening during this heat treatment [FIG. 3 (b)].

Next, the silicon oxide film 11 is etched away by dry etching using CF4 gas to expose the surface of the palladium silicide film 9 in the opening [FIG. 3 (c)].

Thereafter, the wafer is moved to a tungsten growth chamber in the same vacuum, and tungsten 6c is selectively grown by a reduced pressure CVD method using a so-called hydrogen reduction method using WF ₆ gas and H ₂ gas, and an opening is formed. Embed [Fig. 3
(D)].

Subsequently, an aluminum / silicon alloy film 7 is formed by sputtering, and is patterned into a desired shape to form a wiring [FIG. 3 (e)].

In the present embodiment, plasma etching using CF ₄ is not performed only as a pretreatment for growing the tungsten 6c, but also serves as a step of removing the silicon oxide film 11, so that the number of steps is not particularly increased. .

The growth rate of the hydrogen reduction method used in this embodiment is lower than that of the silane reduction method.
Tungsten does not grow on the BPSG film 11 at all even if the tungsten 6c is grown thick because tungsten is difficult to grow on the top.

[0021]

As described above, according to the present invention, when performing selective growth of a refractory metal on a noble metal silicide film by the CVD method, a surface treatment with CF ₄ plasma is performed before the selective growth, whereby the noble metal silicide is obtained. Since the natural oxide film on the film surface is removed and the surface of the insulating film is cleaned without being damaged, re-adhesion of the noble metal silicide to the insulating film surface does not occur. A high melting point metal can be grown on the silicide film.

The surface treatment using CF ₄ plasma can be performed continuously in the same apparatus and in the same vacuum as the apparatus for growing a high melting point metal, so that there is an advantage that the number of steps does not increase. .

[Brief description of the drawings]

FIG. 1 is a sectional view in the order of steps for explaining a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view for explaining the configuration of the present invention.

FIG. 3 is a sectional view in the order of steps for explaining a second embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view for explaining a problem of a conventional method of manufacturing a semiconductor device.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate 2, 5, 8, 11 silicon oxide film 3 polycrystalline silicon film 4a, 4b, 4c platinum silicide film 6a, 6b, 6c, 6d tungsten 7 aluminum / silicon alloy film 9 palladium silicide film 10 BPSG film 12, 13 Diffusion layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI H01L 21/3065 H01L 21/302 F 21/3205 21/88 R 21/768 21/90 C (56) References JP-A No. 2 JP-A-10-69971 (JP, A) JP-A-2-71547 (JP, A) JP-A-61-125014 (JP, A) JP-A-59-94820 (JP, A) JP-A-3-60126 (JP, A) JP-A-2-38568 (JP, A) JP-A-4-199510 (JP, A) JP-A-56-275 (JP, A) JP-A-61-226922 (JP, A) JP-A-1- 217909 (JP, A)

Claims (4)

(57) [Claims] A platinum silicide film or a silicon silicide film on a surface of a silicon layer.
Palladium silicide film is selectively formed, an insulating film is formed, and the platinum silicide film or palladium silicide is formed.
Forming an opening reaching the film in the insulating film; CF
Subjected to a surface treatment by ₄ plasma, a step of removing a natural oxide film on the surface of the platinum silicide layer or palladium silicide film at the bottom of the opening, KoToru in the same vacuum
Go to point metal growth chamber, said platinum silicide
Selectively growing a high melting point metal on the surface of the film or the palladium silicide film and filling the opening with the high melting point metal. 2. A platinum silicide film or a passivation film on a silicon layer.
Forming a radium silicide film , forming an insulating film,
A step of forming an opening reaching the platinum silicide film or the palladium silicide film in the insulating film, a step of thereafter forming a silicon oxide film over the entire surface and performing ion implantation of conductive impurities, and performing a surface treatment with CF ₄ plasma Removing the silicon oxide film; and selectively embedding a high-melting metal in the opening. 3. A step of forming an insulating film on a silicon layer, forming an opening reaching the silicon layer in the insulating film, and selectively forming platinum silicide on the surface of the silicon layer exposed to the opening by heat treatment. Membrane or palladium silisa
Id film is formed, and removing the platinum film or palladium film unreacted subjected to a surface treatment by CF ₄ plasma, removing a natural oxide film of the platinum silicide layer or palladium silicide film <br/> surface Process and high pressure in the same vacuum
Go to melting metal growth chamber, the platinum Shirisai
Selectively growing a high melting point metal on the surface of the doped film or the palladium silicide film and filling the opening with the high melting point metal. Wherein an insulating film is formed on the silicon layer, forming an opening reaching the silicon layer on the insulating layer, selectively platinum silicide film on the silicon layer surface was exposed prior Symbol opening Or a step of forming a palladium silicide film , a step of forming a silicon oxide film on the entire surface and ion-implanting conductive impurities, a step of performing a surface treatment with CF ₄ plasma to remove the silicon oxide film, Selectively embedding a refractory metal in the opening.