JPH0221615A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To suppress breakdown at a step part of a seed part with a shield layer being formed by forming a silicon film which is to become the shield layer at an opening part in an insulating film. CONSTITUTION:A silicon oxide film 11 as an insulating film is formed by deposition or thermal oxidation on a silicon substrate 10. A part of the film 11 is etched away, and an opening part 12 is formed. A doped polysilicon film 13 as a silicon film which is to become a shield layer is deposited on the silicon oxide film 11 including the opening part 12 in the silicon oxide film 11. At this time the thickness of the doped polysilicon film 13 is made sufficiently thicker in comparison with the step at the opening part 12 in the silicon oxide film 11. Therefore, the step of the doped polysilicon film 13 on the opening part 12 is gentle. A LOCOS oxide film 15 is formed on the doped polysilicon film 13. An opening part is provided in the film 15 at the upper part of the opening part 12 in the silicon oxide film 11. The end surface of an opening part 15a is gentle. Therefore, a polycrystalline silicon film 16 on the LOCOS oxide film becomes gentle, and the occurrence of the breakdown at the step part can be suppressed.

Description

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

[Prior art] In recent years, Sol (Silicon On
Development of In5lator technology is underway. At this time, microzone melting using a laser beam, electron beam, etc. is considered to be effective for obtaining a single crystal silicon layer from polycrystalline silicon or amorphous silicon disposed on an insulating film. . At this time, it is necessary to take a seed to align the crystal orientation of the molten recrystallized layer, and for this purpose, an opening is made in the insulating film and the crystal is grown through this opening. In,
A large step had been created.

Furthermore, because shield layers are stacked for the purpose of preventing signal interference between layers in a stacked structure, so-called crosstalk, etc., the steps become larger and the silicon film that becomes the melted recrystallized layer tends to be thinner. Therefore, if a silicon film that becomes a molten recrystallized layer is formed as it is, a step cutout will occur. Therefore, steps such as filling in the opening by etch-back or vertical epitaxial growth of polycrystalline silicon are used to prevent the breakage.

To explain more specifically, as shown in FIG. 4(a),
An opening 3 is provided in a part of the insulating film 2 formed on the silicon substrate 1, and a silicon film 4 serving as a shield layer is formed on the insulating film 2 including the opening 3, as shown in FIG. 4(b). Then, as shown in FIG. 4(C), the silicon film 4 near the opening 3 is removed. Subsequently, a silicon oxide film 5 is formed (FIG. 4(d)), the silicon oxide film 5 in the opening 3 is removed (FIG. 4(e)), and that portion is etched back or polycrystalline silicon is vertically epitaxially grown. (FIG. 4(f)), and then form a silicon film 7 (FIG. 4(CI)).
The silicon film 7 was then recrystallized using a laser beam or the like.

[Problems to be Solved by the Invention] However, among the methods described above, the method of filling the opening 3 by etchback requires a special dry etching device, and the method of filling the opening 3 by vertical epitaxial growth of polycrystalline silicon requires a special dry etching device. Since the embedding method No. 3 requires an epitaxial device, the development of a new method is desired.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a method for manufacturing a semiconductor device that can suppress breakage at a seed portion while forming a shield layer.

[Means for Solving the Problems] A first invention includes a step of forming an insulating film having an opening in a part on the surface of a silicon substrate; a step of forming a polycrystalline or amorphous first silicon film to serve as a shield layer, and a step of recrystallizing the first silicon film on the opening of the insulating film by irradiation with an energy beam; forming a silicon oxide film on the first silicon film with an opening above the opening of the insulating film and having a smooth end surface; A semiconductor device comprising the steps of forming a polycrystalline or amorphous second silicon film, and recrystallizing the second silicon film on the opening of the insulating film by irradiating an energy beam. The gist is the manufacturing method.

Further, a second invention includes a step of forming an insulating film having an opening in a part on the surface of a silicon substrate, and a step of forming a polycrystalline film to be a shield layer on the insulating film including the opening of the insulating film. or a step of forming an amorphous first silicon film;
forming a silicon oxide film having an opening above the opening of the insulating film and having a smooth end face of the opening on the first silicon film; a step of forming a polycrystalline or amorphous second silicon film; and a step of forming a polycrystalline or amorphous second silicon film; The gist of the present invention is a method for manufacturing a semiconductor device, which includes the step of recrystallizing a silicon film in step 2.

[Function] Since the first silicon film serving as a shield layer is formed over the opening of the insulating film, the step becomes gentle, and the end surface of the opening is formed on top of the silicon oxide film with a smooth silicon oxide film. The second silicon film is also formed loosely.

[First Embodiment] A first embodiment embodying the present invention will be described below with reference to the drawings.

FIGS. 1(a) to 1(e) are cross-sectional views showing the manufacturing process of this embodiment.

First, as shown in FIG. 2A, a silicon oxide film 11 as an insulating film with a thickness of 0.7 μm is placed on a silicon substrate 10.
is formed by deposition or thermal oxidation, and a portion thereof is removed by etching to form the opening 12. In this embodiment, the opening 12 is tapered. Note that this opening 12
The silicon oxide film 11 having the above structure may be formed by the LOCO3 method.

Next, as shown in FIG. 2(b), the silicon oxide film 1
A doped polysilicon film 13 serving as a first silicon film serving as a shield layer is deposited to a thickness of 1 μm on the silicon oxide film 11 including the first opening 12 . At this time, since the bead 11 to polysilicon film 13 are made sufficiently thicker than the step difference at the opening 12 of the silicon oxide film 11, the step difference between the bea 11 and the polysilicon film 13 above the opening 12 becomes gentle.

Then, as shown in FIG. 1C, a silicon nitride film 1 of 800 Å is formed on the doped polysilicon film 13 above and around the opening 12 of the silicon oxide film 11.
form 4. Then, the silicon oxide film 11 is irradiated with an energy beam such as a laser beam or an electron beam.
The doped polysilicon film 13 on the opening 12 is recrystallized. That is, when annealing is performed with a laser beam, an electron beam, etc., the silicon nitride film 14 prevents the beam from being reflected and absorbs heat, and the doped polysilicon film 13 under the silicon nitride film 14 is recrystallized and re-irradiated. A crystallized portion 13a is formed.

Subsequently, oxidation is performed while leaving the silicon nitride film 14,
A LOCO3 oxide film 15 as a silicon oxide film with a thickness of 0.8 μm is formed on the doped polysilicon film 13 (see FIG. 3(d)). This LOCO8 oxide film 15 has a rounded end forming the opening 15a, so the same portion is gentle.

Then, the same figure (e) is shown after removing the silicon nitride film 14.
As shown in FIG. 2, a polycrystalline silicon film 16 as a second silicon film is deposited to a thickness of 0.3 μm on the LOCO3 I film 15 including the opening 15a of the LOCO3 oxide film 15.

After that, annealing is performed by irradiation with an energy beam such as a laser beam or an electron beam, and the silicon oxide film 11 is
The polycrystalline silicon film 16 above the opening 12 is recrystallized, and the polycrystalline silicon film 16 around the opening 12 is further recrystallized. At this time, since the recrystallized portion 13a has already been formed in the doped polysilicon film 13, the intensity of the beam may be the energy necessary to melt the polycrystalline silicon film 16.

In this way, in this example, silicon oxide wA11
Since the doped polysilicon film 13 serving as a shield layer is formed on the silicon oxide film 11 including the opening 12, the step of the opening 12 becomes gentle. Further, on the doped polysilicon film 13, a LOCO3 oxide film 41 is formed which is opened above the opening 12 of the silicon oxide film 11 and whose end surface of the opening 15a is smooth.
5 is formed. Therefore, the polycrystalline silicon film 16 on the LOCO3I film 15 becomes loose, and the occurrence of step breaks can be suppressed.

As an application example of this first embodiment, in the above embodiment, a doped polysilicon film 13 is formed immediately after forming a silicon oxide film 11 having an opening 12 on a silicon substrate 10, and a silicon nitride film 14 is used. Although the doped polysilicon 1113 on the opening 12 of the silicon oxide film 11 was recrystallized, the silicon nitride film 14 was re-crystallized without irradiating the silicon nitride film 14 with a laser beam or an electron beam.
The polycrystalline silicon film 16 formed on the LOCO3 film 15 including the opening 15a is exposed to a laser beam, an electron beam, etc. When the laser beam is irradiated and annealed, the doped 1-polysilicon film 13 on the opening 12 of the silicon oxide film 11 is melted by a strong beam and the doped polysilicon film on the opening 12 of the silicon oxide film 11 is melted. Similarly to 13, the polycrystalline silicon film 16 on the opening 12 of the silicon oxide film 11 may be recrystallized.

Also, in the above embodiment, after forming the silicon oxide film 11 having the opening 12 on the silicon substrate 10, the doped polysilicon film 13 is formed, and the silicon nitride film 14 is used to close the opening 12 of the silicon oxide film 11. Although the upper doped polysilicon film 13 was recrystallized, the silicon nitride film 14 was used only to form the LOCO3 oxide film 15 without irradiating the silicon nitride film 14 with a laser beam or an electron beam. 1 without forming the recrystallized portion 13a shown in FIG.
The doped polysilicon film 13 above the first opening 12 may be recrystallized.

Furthermore, another application example will be explained based on FIGS. 2(a) and 2(b). In the above embodiment, the silicon nitride film 14 changes from the state shown in FIG. 1(C) to the state shown in FIG. 2(a).
Using this as a mask, etching is performed to remove a predetermined amount of the doped polysilicon film 13. Then, as shown in FIG. 2(b), a LOCO8 oxide film 17 is formed in the etched portion.

At this time, the doped polysilicon film 13 is placed in the opening 17a of the LOCO3I film 17, and the end face of the opening is formed gently. The preparation of the salt is carried out by the same process as described above. In this case, the upper part of the opening 12 can be made flatter.

[Second Embodiment] A second embodiment of the present invention will be described with reference to FIGS. 3(a) to 3(e).

As shown in FIG. 3(a), a silicon oxide film 21 as an insulating film is formed on a silicon substrate 20 by deposition or thermal oxidation, and a portion thereof is removed by etching to form an opening 22. As shown in FIG.

Next, as shown in FIG. 3(b), a doped polysilicon film 23 is deposited as a first silicon film to become a shield layer on the silicon oxide film 21 including the opening 22 of the silicon oxide film 21. let

Then, as shown in FIG. 3(C), a silicon oxide film 24 is formed on the doped polysilicon film 23, and roughly
As shown in FIG. 3(d), the silicon oxide film 24 above the opening 22 of the silicon oxide film 21 is opened by taper etching.

At this time, since the end surface forming the opening 24a is tapered (slanted), it becomes gentle.

Then, as shown in FIG. 3(e), a polycrystalline silicon film 25 as a second silicon film is deposited and annealed by irradiation with an energy beam such as a laser beam or an electron beam to form a silicon oxide film 21. The doped polysilicon film 23 on the opening 22 of the silicon oxide film 21 and the polycrystalline silicon film 25 on the opening 22 of the silicon oxide film 21 are recrystallized,
Furthermore, the polycrystalline silicon film 25 in the peripheral area is recrystallized.

Also in this embodiment, the opening 2 of the silicon oxide film 21
2, the doped polysilicon film 23 is formed and the end surface of the opening of the silicon oxide film 24 is made gentle. Therefore, the upper part of the opening 22 of the silicon oxide film 21 becomes gentle, and a break in the polycrystalline silicon film 25 occurs. can be suppressed.

Note that this invention is not limited to the above embodiments,
For example, the shield layer and the silicon film to be recrystallized by melting may be made of amorphous silicon instead of polycrystalline silicon.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to manufacture a semiconductor device in which a shield layer is formed and the occurrence of step breakage at the seed portion is suppressed.

[Brief explanation of the drawing]

1(a) to 1(e) are cross-sectional views showing the manufacturing process of a semiconductor device according to a first embodiment of the present invention, and FIG. 2(a)
＞, (b) is a cross-sectional view showing the manufacturing process of a semiconductor device according to an application example of the first embodiment, and FIGS. 3(a) to (e) are cross-sectional views showing the manufacturing process of a semiconductor device according to the second example. , Figure 4(a)
-(Q) are cross-sectional views showing the manufacturing process of a conventional semiconductor device. 10 is a silicon substrate, 11 is a silicon oxide film as an insulating film, 12 is an opening, 13 is a doped polysilicon film as a first silicon film, 15 is a LOGO3 oxide film as a silicon oxide film, and 16 is a second silicon oxide film. 20 is a silicon substrate, 21 is a silicon oxide film as an insulating film, 22 is an opening, 23 is a doped polysilicon film as a first silicon film, 24 is a silicon oxide film , 25 is a polycrystalline silicon film as a second silicon film. Patent applicant Nippondenso Co., Ltd. Agent Patent attorney On 1) Hironobu (a)

Claims (1)

[Claims] 1. A step of forming an insulating film having an opening in a part on the surface of a silicon substrate, and forming a polycrystalline film to serve as a shield layer on the insulating film including the opening of the insulating film. Alternatively, a step of forming an amorphous first silicon film, a step of recrystallizing the first silicon film on the opening of the insulating film by irradiation with an energy beam, and a step of recrystallizing the first silicon film on the opening of the insulating film. a step of forming a silicon oxide film having an opening above the opening of the insulating film and having a smooth end surface of the opening; and forming a polycrystalline or amorphous silicon oxide film on the silicon oxide film including the opening of the silicon oxide film. A method for manufacturing a semiconductor device, comprising: forming a second silicon film; and recrystallizing the second silicon film on the opening of the insulating film by irradiating an energy beam. . 2. Forming an insulating film having an opening in a part of the surface of the silicon substrate, and forming a polycrystalline or amorphous film to serve as a shield layer on the insulating film including the opening of the insulating film. forming a silicon oxide film having an opening above the opening of the insulating film and having a smooth end surface of the opening on the first silicon film; forming a polycrystalline or amorphous second silicon film on the silicon oxide film including the opening; and irradiating the first silicon film on the opening of the insulating film with the insulating film by irradiating an energy beam. A method of manufacturing a semiconductor device, comprising the step of recrystallizing the second silicon film on the opening of the film.