JPH03171757A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obviate the need for forming a conductive film by the photodetecting process, to eliminate the unetched part, to obviate the need for mask matching and to reduce failure rate for achieving miniaturization by selectively forming a second conductive film by the selective growth method. CONSTITUTION:An impurity region 5 is formed on a semiconductor substrate 1 with a second insulation film 4 and a conductive film 3 as masks. Then, a third insulation film 6 is formed. Then, a contact hole 7 is provided, thus exposing one part of the impurity region 5. After that, by performing crystal growth for the semiconductor substrate 1, a polycrystal silicon is allowed to grow selectively at the exposed impurity region 5 through the first contact hole 7 and then a second conductive film 8 is selectively formed by doping phosphor to it. Thus, since the second conductive film 8 is formed by the selective crystal growth, it is not necessary to use an etching using a photo mask when forming the second conductive film and the mask matching accuracy in this case does not produce any problem.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a self-aligned contact. [Prior Art] FIG. 2 is a longitudinal sectional view of a semiconductor device having a conventional self-aligned contact. In the figure, a P-type silicon substrate 1
by oxidizing the surface of the first insulating material W made of silicon oxide.
i! 2 is formed. And this first insulation 11g
2. A first conductive material y made of polycrystalline silicon containing phosphorus on
I am admonishing I3.

Next, a second conductive film made of silicon oxide is placed on the first conductive film 3.
An insulating film 4 is provided, and the second insulating film 4 and the first conductive film 3 are patterned using the same mask using a photo-etching method. Next, using the second insulating film 4 and the first conductive film 3 as masks, an N-type impurity such as arsenic is introduced into the semiconductor substrate 1 to form an impurity region 5. Next, a third insulating film 6 made of silicon oxide is formed on the entire surface, and a first contact hole 7 is formed by selective etching so that the first conductive film 3 is not exposed. expose a part.

Next, a third conductive layer (for wiring) is applied to the region including the first contact hole 7 so as to be electrically connected to the impurity region 5.
A self-aligned contact is achieved by providing an IA and patterning it by photo-etching. [Problems to be Solved by the Invention] In the conventional self-aligned contact described above, in order to improve the insulation reliability of the third insulating film 6, it is necessary to form the third insulating film 6 thickly as shown in FIG. , it becomes difficult to control the etching of the third insulating film 6 when opening the l-th contact hole 7, and the first conductive lI! 3 is easily exposed. For this reason, the third
There is a problem in that the conductive film 11 and the first conductive film 3 are likely to come into contact with each other, resulting in an electrical short circuit.

For this reason, a self-aligned contact shown in FIG. 4 has been proposed as another structure. This contact is made by forming a thin third insulating film 6At, opening a first contact hole 7, and then providing a second conductive film 8A made of phosphorous-doped polycrystalline silicon and using a foot etching method. The patterning is performed so as to completely cover the first contact hole 7 and to extend around the first contact ball 7 to some extent. Then, a sufficiently thick fourth insulating film 9 made of BPSG (boron phosphorus glass) is formed on the entire surface, and after reflow, a second insulating film 9 is formed by photo-etching so that only a part of the second conductive film 8A is exposed. A contact hole 10 is formed. At this time, the second conductive film 8A acts as an etching stopper, and the first conductive film 3 is not exposed.

Next, a third conductive film l1 made of aluminum is provided so as to be electrically connected to the second conductive film 8A via the second contact hole 10.

However, in this self-aligned contact, since the third insulating film 6 is thin, its flatness is not sufficient, and etching remains are likely to be left when patterning the second conductive film 8A. Further, since the second conductive film 8A needs to be patterned using a photoetching method, there is a problem in the accuracy of mask alignment, which impedes miniaturization. The present invention solves these problems and provides a method for manufacturing a semiconductor device that prevents short circuits with the first conductive film and enables miniaturization.

[Means to solve the problem]

The method for manufacturing a semiconductor device of the present invention includes sequentially forming a first conductive film and a second insulating film on a first insulating film provided on a surface of a semiconductor substrate, and etching these into a desired pattern. Furthermore, a third insulating film is formed on the entire surface, and the first
After opening a first contact hole in the third insulating film to expose a part of the semiconductor substrate so as not to expose the conductive film, a second contact hole is formed on the exposed semiconductor substrate by a selective length method. A conductive film is selectively formed. Moreover,
, a fourth insulating film is formed on the entire surface, and a second contact hole is formed in the fourth insulating film so that a part of the second conductive film is exposed, and the second contact hole A third conductive film is formed to be electrically connected to the second conductive film through the conductive film.

[Effect]

In this manufacturing method, the second conductive film is selectively formed by a selective or lengthening method, so there is no need for a photo-etching process when forming the second conductive film, and no etching residue is left. , moreover, there is no need for mask alignment. Furthermore, by forming the fourth insulating film, it becomes possible to obtain sufficient insulation reliability. [Example] Next, the present invention will be described with reference to the drawings.

FIGS. 1(a) to 1(C) are longitudinal sectional views showing an embodiment of the present invention in the order of steps. First, as shown in FIG. 1(a), the surface of a semiconductor substrate 1 made of P-type silicon single crystal is oxidized to form a first insulating film 2 made of silicon oxide with a thickness of about 200λ. Then, on this first insulating film 2, a first conductive film 3 made of polycrystalline silicon containing phosphorus is formed to a thickness of about 2,000 layers. Further, on this first conductive film 3, a second insulating film 4 made of about 2,000 silicon oxides is provided.
Then, the second insulating film 4 and the first conductive film 3 are patterned by photo-etching using the same mask.

Next, using the second insulating film 4 and the first conductive film 3 as masks, an N-type impurity such as arsenic is added to the semiconductor substrate 1.
An impurity region 5 is formed by introducing energy TE4XIQISc@-Z of 0 KeV.

Next, as shown in FIG. 6B, a third insulating film 6 made of silicon oxide is formed over the entire surface to a relatively thin thickness, for example, about 2000 μm thick. Then, the third insulating film 6 is photo-etched so that the first conductive film 3 is not exposed.
A first contact hole 7 is opened to expose a portion of impurity region 5.

Then, by performing crystal lengthening on the semiconductor substrate l, the polycrystalline silicon is selectively lengthened to a certain extent in the impurity region 5 exposed through the first contact hole 7, and phosphorus is added to the polycrystalline silicon. The second conductive film 8 is selectively formed by doping. The thickness of this second conductive M8 is, for example, 1.2
Let it be μm.

Next, as shown in FIG. 2C, a fourth insulating film 9 made of BPSG is formed to a thickness of 1 μm over the entire surface, and is reflowed to planarize the surface. Then, a second contact hole 10 is formed in the fourth insulating film 9 so that only a part of the upper surface of the second conductive film 8 is exposed. Furthermore, a third conductive film 11 for wiring is provided so as to be electrically connected to the second conductive film 8 through this second contact hole 10, and this is patterned by photo-etching. Self-aligned contact is perfected.

Therefore, in the self-aligned contact manufactured in this way, by making the third insulating film 6 thinner, it is possible to easily control etching when opening the first contact hole 7, and this etching makes it possible to easily control the etching when opening the first contact hole 7. Conductive film 3
The contacts will not be exposed and short circuits with contacts can be prevented. In addition, in this method, since the second conductive film 8 is formed by a selective crystal growth method, there is no need to use etching using a photomask when forming the second conductive film. There is no problem with the accuracy of mask alignment.

Note that the second conductive film 8 is made of tungsten, and the fourth conductive film 8 is made of tungsten.
The insulating film 9 may be a silica coated film. This has the advantage that the second conductive film 8 and the fourth insulating film 9 can be manufactured at a low temperature, and that the effects of high temperature on the impurity region 5 and the like can be eliminated. [Effects of the Invention] As explained above, in the present invention, since the second conductive film is selectively formed by the selective lengthening method, there is no need to form this conductive film by a photo-etching process, and the etching residue is removed. This eliminates the need for mask alignment, which has the effect of reducing the defective rate and realizing miniaturization. Furthermore, it becomes possible to form a sufficiently thick fourth insulating film, which has the effect of increasing the reliability of insulation.

[Brief explanation of the drawing]

1(a) to 1(c) are longitudinal sectional views showing an embodiment of the present invention in the order of manufacturing steps, FIG. 2 is a longitudinal sectional view of an example of a conventional self-aligning contact, and FIGS. FIG. 4 is a longitudinal sectional view for explaining problems in different conventional manufacturing methods. DESCRIPTION OF SYMBOLS 1... Semiconductor substrate, 2... First insulating film, 3...
First conductive film, 4... Second insulating film, 5... Impurity region, 6.6A... Third insulating film, 7... First contact hole, 8,8A... ...Second conductive film, 9
... Fourth insulating film, 10... Second contact hole, 11, IIA... Third conductive film. Figure l Figure 2

Claims (1)

[Claims] 1. A step of sequentially forming a first conductive film and a second insulating film on the first insulating film provided on the surface of the semiconductor substrate and etching them into a required pattern, and a step of forming a third insulating film on the entire surface. forming a film and opening a first contact hole in a third insulating film so as not to expose the first conductive film to expose a part of the semiconductor substrate; a step of selectively forming a second conductive film on the substrate by a selective growth method; and a step of forming a fourth insulating film on the entire surface, and forming a fourth insulating film so that a part of the second conductive film is exposed. The method includes the steps of forming a second contact hole in an insulating film, and forming a third conductive film electrically connected to the second conductive film through the second contact hole. A method for manufacturing a semiconductor device.