JPS62243324A - Manufacture of semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To avoid conductor discontinuity and improve reliability such as electromigration resistance by a method wherein, after a contact hole is formed, a semiconductor thin film or a thin film containing metal is formed on the side surface and the bottom surface of the contact hole only and then the con tact hole is selectively filled with metal. CONSTITUTION:After a high concentration diffused layer 2 is formed in a semiconductor Si substrate 1, an insulating film 3 is formed on the substrate 1 and a contact hole 4 is drilled in the insulating film 3 to expose the diffused layer 2. Then a thin polycrystalline Si film 5 is deposited over the whole surface. Resist 6 is applied to the whole surface to level the surface. Successively, the resist 6 is etched over the whole surface and left in the contact hole 4 only the polycrystalline Si film 5 is etched with the remaining resist 6 as a mask so as to be left on the side surface and the bottom surface of the contact hole 4 only. After the resist 6 is removed, gas composed of WF6 diluted by Ar is made to react with the polycrystalline Si film 5 to deposit a W film 7. Then WF6 is made to react with gas containing H2 and W 7 is made to grow by utilizing hydrogen reduction reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a high-density, large-scale integrated semiconductor integrated circuit having fine electrode contacts and multilayer wiring.

[Prior art] When forming electrodes on contacts, usually a person
These metals are used, and the sputtering method is adopted as the deposition method. However, the contact width is 1 μm
When the micro-dimensions are smaller than the following, in the AI sputtering method, most of the mulch adheres to the side surfaces of the contact, which becomes difficult. the result,
Significant reliability problems such as wire breakage and electromigration resistance will occur.

To prevent this, there is a technique for selectively embedding metal in the contacts. An example of this is shown below.

FIG. 9 shows a cross-sectional view when metal is selectively embedded in fine contacts using a conventional manufacturing method.

In the figure, 8 is a semiconductor substrate, 9 is a diffusion layer, 10 is an insulating film, 11 is a contact hole, 12 is tungsten, a high melting point metal, embedded in the contact hole 11, 13 is tungsten deposited on the insulating film, 14 is the tungsten that has entered the diffusion layer.

This was formed by the manufacturing method described below. That is, after opening the contact hole 11 in the insulating film 1o, wF6(
Tungsten hexafluoride) is reacted with the substrate silicon 8 to selectively grow 2wF6+38tungsten (2w+38iF4 tungsten (b)) 12 in the contact hole 11. At this time, this occurs because the silicon substrate is exposed at the bottom of the contact hole 11. In other words, if the reaction is allowed to occur for a long time, reaction by-products and insulating film 1 that adhere to the insulating material 1° will be removed.
W13 is deposited centering on the nucleus that is originally present on the surface of the wafer. In this way, W1 is placed on the insulating film 1o.
3 is deposited, selectivity is lost and contact hole 1
It becomes impossible to embed W12 only in 2.

This method has a limit of selective growth of W to a thickness of approximately 2000 to 3000 μm, and it is not possible to completely bury a contact having a depth of 0.5 to 1 μm.

Furthermore, in the periphery of the bottom surface of the contact 11, W14 penetrates into the diffusion layer 9 due to stress in the insulating film 10, etc.
This leads to destruction of the bond between the diffusion layer 9 and the semiconductor substrate 8.

As mentioned above, with conventional manufacturing methods, it is not possible to embed W thickly, which may lead to disconnection of wiring or
Reliability issues.

Problems such as bond breakdown may occur.

+ 1\The present invention was made in view of the drawbacks of the conventional technology, and is a simple method that
The purpose is to prevent contact destruction due to metal intrusion and to selectively fill contact holes with metal.

Means for Solving Problems 6, -7 The present invention solves the above problems by forming a thin semiconductor film or a thin film containing metal only on the side and bottom surfaces of the contact hole after forming the contact hole. . Thereafter, a gas containing metal is reacted to selectively fill the contact hole with metal.

Function The present invention is capable of forming electrode wiring in minute contact holes without disconnection by the above-described method, and is also effective in preventing damage to the contacts and improving reliability of the wiring.

Embodiment FIG. 1 is a sectional view of a fine contact completely filled with metal (tungsten) in an embodiment of the present invention.

In the figure, 1 is a semiconductor substrate (silicon layer), 2 is a high-concentration diffusion layer (silicon layer), 3 is an insulating film, 4 is a contact hole, and 5 is selectively formed on the side and bottom of the contact hole 4. A polycrystalline silicon film 7 is tungsten (W) selectively buried in the contact hole 4 .

The manufacturing method will be explained with reference to FIGS. 2 to 8. In FIG. 2, 1 is a semiconductor silicon substrate, 2 is a high concentration diffusion layer, and 3 is a semiconductor silicon substrate.
A contact hole 4 is formed in an insulating film, and the diffusion layer 2 is exposed. In FIG. 3, a polycrystalline silicon film 5 is deposited on the entire surface by CVD to a thickness of 100 to 1000 mm. In this case, a film containing metal may be deposited instead of the polycrystalline silicon film. For example, w8i2, w, Mo
, MoSi2, etc. Since the CVD method has good step coverage, a film is sufficiently deposited on the side surfaces of the contact hole 4.

In FIG. 4, the entire surface is coated with a resist 6, and since the resist 6 used to planarize the surface is liquid, the contact hole 4 is completely filled with the resist 6.

Subsequently, in FIG. 5, the entire surface of the resist 6 is etched by a dry etching method, leaving only the contact hole 4 as the resist 6. The thickness of the resist 6 in the contact hole can be controlled by the etching time. Since a thick resist 5 remains on the contact hole 4, this process can be performed using any material that can fill the hole 4 and remove the above material without etching the thin film 5 and the insulation 3. For example, polyimide may be used. In FIG. 6, polycrystalline silicon film 5 is etched using resist 5 as a mask, leaving polycrystalline silicon film 6 only on the side and bottom surfaces of contact hole 4. In FIG. 7, after the resist 6 is removed, a gas prepared by diluting wF6 (e-tungsten fluoride) with argon (argon) is reacted with the polycrystalline silicon film 5 to deposit a tungsten film (W). That is, tungsten 7 is selectively grown only on the side and bottom surfaces of contact hole 4 using the silicon reduction reaction of 2wF6-1-38i→2w-4-38iF4.

In this reaction, wF6 mainly reacts with polycrystalline silicon 5, and therefore hardly reacts with single-crystal silicon diffusion layer 1 present in semiconductor substrate 1. Therefore, the phenomenon in which wF6 reacts with the diffusion layer 2 and tungsten invades along the interface of the insulating film 3, and the phenomenon in which wF reacts with the diffusion layer 2 and tungsten advances in the vertical direction and destroys the junction are prevented. . As a result, junction breakdown and contact breakdown due to tungsten 7 do not occur. Next, in Fig. 8, wF6 and H2
(hydrogen)-containing gas to react. That is, WF6 +
3 Tungsten 7 is grown using the hydrogen reduction reaction of H2→w+eHF. At this time, since hydrogen has the property of adsorbing and ionizing only on the metal surface, the hydrogen reduction reaction grows only from the side and bottom surfaces of the contact hole 4 and does not grow on the insulating film 3. Further, in the contact hole 4, since deposition by reaction from the side surface is also utilized, the contact hole 4 can be filled in a short time. For example, for a contact hole with an aspect ratio of 1, the time is halved. Furthermore, the finer the contact, the greater the effect. If the growth time is short, reaction by-products will not adhere to the insulating film 3, and the insulating film 3 will not adhere to the insulating film 3 from the beginning.
Tungsten is not deposited around the overlying core. Therefore, selectivity is maintained and the height of the polycrystalline silicon 5 attached to the side surface of the contact hole 4 can be controlled, improving the flatness of the tungsten 7 embedded in the contact hole 4. I can do it. After this, electrodes and wiring can be easily formed using a normal sputtering method.

In this example, in Figs. 7 and 8, an example was shown in which wF6 was used as the metal-containing gas, but other gases such as MoF6, Mo(GO)6, and W(CO)6 were used. Similarly, Mo or W can be deposited.

Further, the diffusion layer 2 shown in FIGS. 1 to 8 is a silicon layer, and on the surface thereof, w Si2 , Ti Si2 ,
MoSi2.

It goes without saying that the method of the present invention can be used even if there is a film of Mo, Ti, etc.

Effects of the Invention As described above, according to the present invention, fine contact holes can be selectively filled with metal using a simple method without destroying the contacts, so even if electrodes and wiring are formed, This has a significant effect on improving reliability, such as electromigration resistance, with no wire breakage. Therefore, it becomes easy to realize a high-density, large-scale semiconductor integrated circuit.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a fine contact according to an embodiment of the present invention, Figs. 2 to 8 are cross-sectional views for explaining the manufacturing process of the above-mentioned fine contact, and Fig. 9 is a cross-sectional view of a conventional manufacturing method. FIG. 3 is a cross-sectional view of a fine contact. 1... Semiconductor substrate, 2... Diffusion layer, 3
...Insulating film, 4...Contact hole, 5...Polycrystalline silicon film, 7...Tungsten (W) embedded in the contact hole.

Claims (2)

[Claims] (1) A first step of forming a contact hole for an electrode or wiring in an insulating film on a semiconductor substrate, and a second step of forming a thin semiconductor film or a film containing a first metal only on the side and bottom surfaces of the contact hole. A method for manufacturing a semiconductor integrated circuit, comprising step 2 and a third step of reacting a gas containing a second metal to selectively grow the second metal in the contact hole. (2) The second step is a step of forming a semiconductor film, a film containing the first metal, and a coating film having different etching characteristics from the insulating film on the entire surface including the contact hole so that the surface is flattened. , a step of etching the coating film to leave the coating film only in the contact hole; using the coating film as a mask, removing the semiconductor film or the film containing the first metal and etching the coating film on the side and bottom surfaces of the contact hole; 2. The method of manufacturing a semiconductor integrated circuit according to claim 1, further comprising the steps of: forming the semiconductor film or the film containing the first metal only thinly; and removing the coating film.