JPS6210007B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a semiconductor device.

In the integrated circuit manufacturing process, it may be necessary to introduce impurities only into specific holes among multiple holes simultaneously drilled in the insulating film. Shielded with photosensitive resin.
However, if the distance between the aperture that introduces impurities and the aperture that does not introduce impurities are adjacent to each other, that is, as the element becomes finer, the distance between the two apertures becomes closer, and the distance between the apertures becomes the alignment error distance. If the two apertures are close to each other, it becomes difficult to separate the two apertures with good reproducibility using the photosensitive resin. This is because as the distance becomes narrower, the effect of the difference in unevenness due to the opening becomes noticeable.

FIG. 1 explains a conventional technique in which a first insulating film 2, for example silicon dioxide, is grown on a semiconductor substrate 1 having a first conductivity type, and a plurality of openings are formed in the insulating film. When it is not necessary to introduce an impurity into the opening 3 and only into the opening 4, the opening 3 is shielded with a photosensitive resin 5, and then the impurity is introduced into the substrate by ion implantation or the like. will be introduced in At this time, impurities are introduced into the openings 4, but the photosensitive resin 5 serves as a protective film, and no impurities are introduced into the openings 3. In this method, it is necessary to position the photosensitive resin end 6 between the openings 3 and 4, and as the device becomes finer and the distance l between the openings 3 and 4 becomes shorter, the resin end 6 must be positioned between the openings 3 and 4. It becomes difficult to keep the distance within the hole distance l with good reproducibility.

An object of the present invention is to form a protective film only in desired openings by self-alignment, regardless of the alignment accuracy of the prior art.

The present invention provides a method for manufacturing a semiconductor device having a plurality of openings in an insulating film on a semiconductor substrate, introducing impurities only into specific openings among the openings, and not introducing impurities into other openings. In this step, a first film having a property of reducing unevenness on the surface of a semiconductor substrate and made of a material different from a photosensitive resin is formed, and after removing a portion of the film formed in the convex portion, a second film is formed. form a film,
A region including any recesses on the main surface of the second film made of the photosensitive resin is selectively opened;
The first film in the arbitrary concave portion is removed using the film as a protective film, and after the second film is removed, impurities are introduced into the semiconductor substrate using the first film. have By using the present invention, a protective film can be formed only in desired openings by self-alignment regardless of the alignment accuracy of the photosensitive resin, and impurities can be introduced only into openings where no protective film is formed. has.

FIG. 2 is an explanatory diagram of the first embodiment of the present invention. An insulating film 22, such as a silicon dioxide film, is formed on the semiconductor substrate 21, a plurality of openings are formed in the film 22, and then an emulsion type oxide is applied and fired. At this time, the rotation speed of the rotary coating machine is
At 4000 rpm, the emulsion type oxide thickness is
Since it is thin, around 1000 Å, the desired oxide film thickness can be obtained by lowering the rotation speed or performing double or triple coating as necessary. The emulsion type oxide thus formed is thin on the insulating film 22 and thick on the openings 23 and 24. Therefore, even after removing the thinly formed emulsion type oxide on the membrane 22, the openings 2 remain.
3, 24 contains emulsion type oxide 26,
27 remain. Next, selective holes are made with photosensitive resin 25 so as to cover the holes 23. At this time, the photosensitive resin 25 may partially cover the opening 24 as shown in the figure. Next, when the emulsion type oxide 26 is removed using the resin 25 as a protective film, the emulsion type oxide 27 remaining in the opening 23 remains even after the resin 25 is removed. Next, if an impurity is introduced using an ion implantation method or the like, the impurity will be introduced into the opening 24, but the emulsion type oxide 27 remaining in the opening 23 will serve as a protective film, and the opening 23 will become a protective film.
No impurities are introduced into 3. Also, a third film of a different type, such as a silicon nitride film, is formed under the emulsion type oxide, and the other different type of film is removed using the emulsion type oxide as a mask, and the selectively removed third film is removed. Impurities may be introduced using the film as a protective film. Furthermore, as a method for introducing impurities, not only the ion implantation method but also other methods such as thermal diffusion may be used.

FIG. 3 is an explanatory diagram of a second embodiment of the present invention. As shown in FIG. 3a, after forming a gate insulating film 32 and a gate electrode 33 on a semiconductor substrate 31 having a first conductivity type, an emulsion type oxide 34 is applied to a portion corresponding to the electrode 33 of the oxide. Remove the part. Next, as shown in FIG. 3B, a photosensitive resin 35 is formed to shield at least the emulsion type oxide 34A, and then the emulsion type oxide 34B is removed using the resin 35 as a protective film. Next, as shown in FIG. 3c, by using the oxide 34A as a protective film and introducing an impurity having a second conductivity type different from the conductivity type of the substrate by ion implantation or the like, an emulsion-type oxide-free hole is formed. An impurity region 36 is formed in that portion. Next, as shown in FIG. 3d, after removing the oxide 34A, an impurity having a second conductivity type is introduced by a thermal diffusion region or by ion implantation. In the part where the impurity region 36 was formed, a region 37 with a deep impurity region depth and low electrical resistance is formed, and in the part where the region 36 was not formed, a region 37 with a high electrical resistance but with a low impurity region depth is formed. shallow area 38
is formed. Next, as shown in FIG. 3e, the electrode 39
and 40. When the electrode 40 is used as a drain and the electrode 39 is used as a source, a field effect transistor with high breakdown voltage between the source and drain and low electric resistance in the source region can be obtained. As explained with reference to FIGS. 3a to 3e, by using the method of the present invention, even when the device is miniaturized and the width of the gate electrode 33 becomes narrow, it can be realized with good reproducibility regardless of the width of the gate electrode 33.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a method of manufacturing a semiconductor device according to the prior art, and FIG. 2 is a sectional view showing an embodiment of the present invention. FIGS. 3a to 3e are cross-sectional views showing another embodiment of the present invention in the order of steps. In the figure, 1, 21, 31 are semiconductor substrates, 2, 22 are insulating films, 3, 4, 23, 24 are openings, 5, 25, 35 are photosensitive resins, 6 is photosensitive resin ends, 26 , 27, 34, 34A, 34B are emulsion type oxides, 32 is a gate insulating film, 3
3 is a gate electrode, 36 is a second conductivity type impurity region, 37 is a region with low electrical resistance, 38 is a region with high electrical resistance, and 39 and 40 are electrodes.

Claims (1)

[Claims] 1. Forming a first film made of emulsion type oxide on the uneven main surface of a semiconductor substrate, thicker in the recesses and thinner in the convex parts; After removing the first film to make the top surface of the convex portion and the top surface of the first film in the concave portion substantially flat, a second film made of photosensitive resin is applied to the top surface of the convex portion and inside the concave portion. selectively opening a region including a predetermined recess on the main surface of the second film;
removing the first film in the predetermined recess using the second film as a protective film; and removing impurities from the semiconductor substrate using the first film remaining after removing the second film as a protective film. 1. A method for manufacturing a semiconductor device, characterized by introducing the semiconductor device into a semiconductor device.