JPS5844735A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the integration of a semiconductor device by forming a polysilicon film on a V-shaped groove surface fromed on an epitaxial layer on an Si substrate, oxidizing the polysilicon film, the epitaxial layer under the film and the surface of the substrate, thereby suppressing the formation of bird beak. CONSTITUTION:An N type epitaxial layer 2 is superposed on an P type Si substrate 1, an Si3N4 mask is coated on an SiO2 film 3, a V-shaped groove is formed, and the groove surface is covered by a CVD method with polysilicon 11. The polysilicon 11 and the surface of the epitaxial layer 2 under the polysilicon and the surface of the substrate 1 are thermally oxidized and are partly formed to SiO2 12. Since the oxidation of the polysilicon is fast, the bird beak formed at the V-shaped groove edge is less. Then, the V-shaped groove is completely filled with the polysilicon as the conventional method, is lapped to Si3N4 film 4, and the polysilicon 13 remains only in the groove. The surface of the polysilicon 13 is thermally oxidized to form a thick SiO2 14. Then, no large bird beak is produced. When the Si3N4 is etched, useless area due to the bird beak can be reduced, thereby improving the integration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, more specifically, 1V or rtLl*? The next insulating layer separation structure filled with polycrystalline silicon? The present invention relates to a method of manufacturing a semiconductor device having the present invention.

In semiconductor integrated circuits - 1 Oka - Many active and passive elements are built into a substrate to form a circuit function, and these elements are separated so that they are not affected electrically by each other (isolation). There is a need to. This separation includes methods such as PN junction separation, air layer separation, insulation layer separation, and separation using a combination of these. One of the methods of the present invention is to form an insulating mt shadow on the inner surface of a or U groove formed in a semiconductor substrate, and to separate an insulating layer by disposing polycrystalline silicon on the insulating film, so-called V I P (V-groo
veIsolation Polycry9tal B
ACKF II) relates to the next semiconductor device using the structure.

■ A semiconductor device having an IP structure is manufactured as follows (see Figures 1 to 6). As shown in Figure 1, for example, a NW Silicon epitaxial growth layer 2 (for example, thickness 2.
apwl)'t formed in an epitaxial growth apparatus.

Then, a thermal oxidation method or CVD (Chemical Vapor I) is applied to the surface of the N-type epitaxial growth layer 20.
Silicon dioxide (8
402) Forming a film 3 (for example, thickness 1500 [people]),
On top of that, silicon nitride <5ksNa) is applied by CVD method.
A film 4 (for example, thickness 2000 (λ)) is formed.

A photoresist (not shown) is coated on the N4 film 4, and exposed and developed through a mask having a predetermined pattern.

Then, the Si 3N film 4 is selectively etched as the photoresist t mask. This engineering! is called photoetching. Subsequently, 1S02 film 5 is selectively etched, and the remaining 8i02 film 3 and 5 are etched.
The epitaxial growth layer 2 and the single crystal substrate 1 are anisotropically etched using the A3N4 film 4t mask to form nine grooves as shown in FIG. The K5i5N4 film 4 is etched and removed to an appropriate hole size so that the photoconductor in the V-groove reaches the inside of the substrate 1. t+, V-groove margin r)vcU@ can also be formed by isotropic machining or ching.

Next, the surface of the V-groove is oxidized by thermal oxidation to form 810
2 membranes 5 (for example, thickness 50 mm) 1 are formed as shown in FIG. At this time, there is a ノ(-Dobikuro) on the edge of the groove.
3 i It occurs to push up the 5N4 film 4'.

Next, V
At is formed on the entire surface so as to completely fill it. and,
Wrapping the polysilicon layer with 4t of 813N4 film ■
Polysilicon 7 (brown figure 4) is left only in the groove.

Next, the surface portion of the polysilicon 70 is thermally oxidized to form a thick s
An i02 film 8 (for example, 8,000 mm thick) is formed as shown in FIG. 5. At this time, the bird's beak formed earlier becomes an even larger bird's beak 9.

Then, the 513Na film was removed by etching 4 times (Figure 6).
, Evita middle layer 2t due to isolation area
Predetermined transistors, resistors, and other elements (not shown) are formed in the predetermined nine-chip formation region to form a semiconductor device W.
/1 (IC, L8I', etc.) k Complete.

When a semiconductor device is manufactured using the conventional process described above, an oxide film 1 with a bird's beak of 2f is produced! This results in a relatively large area (1 to 1.5 [2 m3 width)], creating a wasted area that hinders the integration of integrated circuits.

The purpose of the present invention is to increase the degree of integration while keeping the size of the bird beak smaller than that of the resident bird beak.

Another object of the present invention is to provide a method for manufacturing a semiconductor device that can reduce bird's beak when forming an insulating layer isolation structure.

For the above purpose, insulating layer separation of semiconductor devices is performed in steps (71 to 71).
(, 6: Step of forming a silicon epitaxial growth layer on eF'l silicon single crystal substrate; 0) Reaching silicon single crystal substrate by selective etching ■ or Uill
(15) Process of forming a 5i02 film r with acid on the surface portion of V or σU: (2) Process of filling the inside of the groove with polysilicon; and (9) Filling the surface of the groove with polysilicon. In the method of manufacturing a semiconductor device achieved by the step of oxidizing the surface portion, the above-mentioned V or rt
After the U #I formation step, a polysilicon film is formed on the surface of this # or U groove, #iJ, and then this polysilicon film, the epitaxial growth layer underneath it, and the a of the single crystal substrate are formed.
This is achieved by a method for manufacturing a semiconductor device characterized by forming the aforementioned oxide film tube by t-oxidizing the rkJ portion.

■The 5102 film formed by oxidizing the polysilicon film on the U# surface and the silicon trench surface [fiO1] below it corresponds to the 5i02 film formed by oxidizing the trench surface in the conventional process. Since the thickness of the epitaxial growth layer and the single crystal substrate on the surface of the groove is thinner in the method of the present invention than in the conventional method, the occurrence of I(-dobeek) can be reduced.For example, if the thickness of the 8102 film is 1500 In this case, in the conventional method, when epitaxial growth is performed, the thickness to be oxidized on the groove surface portion of the substrate is 2,500 mm.
In the method of the present invention, the thickness of the polysilicon film to be oxidized is 67,500 mm, assuming that the polysilicon film is 12 mm thick.

Hereinafter, a method for manufacturing a semiconductor device according to the present invention will be explained in detail with reference to the accompanying drawings. , Si3N4 by photo-etching method
The film and the 5i02 film are selectively etched, and using these insulating films as a mask, a V-groove or U#l4pt second
The etching process is the same as the conventional process described above.

According to the present invention, (1) After the groove is formed, as shown in FIG.
It is formed on the entire surface including the surface of the groove (1) provided in the single crystal group &1 and the epitaxial growth layer 2 by method D.

Next, not only the entire polysilicon film 11 is oxidized by thermal oxidation, but also a portion (for example, 500 mm thick) of the polysilicon film 11Q, the surface of the underlying epitaxial growth layer, and the surface of the single crystal base 1&i are oxidized. Then, as shown in Figure @8, a 8402 film 12 (thickness 5 ooo) is formed. In this thermal oxidation process, the oxidation rate of the silicon film 11 is large; The processing time is short, and the amount of bird beaks that occur in the V-groove ruts is small.

Next, as in the conventional process, a polysililane layer is formed on the entire surface by tCVD so as to completely fill V#. Then, the polysilicon layer t8i5Na is roughed up to the film 4, leaving the polysilicon layer 13i only in the groove (9th layer).
figure).

Next, the surface portion of the polysilicon 150 in the trench is thermally oxidized to form a thick 5iuz film 14 (for example, 8000 mm thick).
) k Form as shown in Figure 10. This 5102 membrane 14
This corresponds to the 8102 film 8 in the ¥5 figure. At this time, since polysilicon 13 has a large oxidation rate,
The desired oxidation can be carried out in a relatively short oxidation treatment, and the bird's beak hardly grows and no large bird's beak is generated.

After that, the 5i5N4 film 4t is removed by etching (FIG. 11), and the semiconductor device is completed by forming an epitaxial layer 42 defined by the isolation exposed region in the nine element forming regions by a method known in the art.

As is clear from FIG. 11, when the bird's beak is manufactured according to the method of the present invention, it is considerably smaller than the conventional method. It is possible to improve the degree of

[Brief explanation of the drawing]

FIGS. 1 to 6 are partial cross-sectional views of a semiconductor device illustrating a semiconductor device manufacturing process by a conventional method, and FIGS. 7 to #! FIG. 11 is a partial sectional view of a semiconductor device illustrating a semiconductor device manufacturing process by the method of the present invention. 1-0.Silicon single crystal substrate, 2@...Silicon Ebitashal growth layer, 3..O.8jOzl[,
4...S Todoroki sN4 membrane, 5...8 i02
Membrane, 6 9・oI+ Birdbeak, 7・0・Polysilicon, 8@@1111Sai5i02 membrane,
1111@@@ Polysilicon film, 12...
b Otori 02HAs ”・・・Polysilicon,
14... Rhinoceros 8102 membrane. Patent applicant Fujitsu Ltd. Patent agent Akira Ikuki Kazuyuki Nishidate (patent attorney) 1) Yukio patent attorney Akira Yamaguchi (patent attorney)
Kona 瀞大 r-ku 1, T -0 Ken poor Kona 6 ward ■ To daughter Kona string 〇- 耘

Claims (1)

[Claims] Insulating layer separation of semiconductor devices is performed using the following process! ! φ~ (shown: (7)
Step of forming a silicon epitaxial growth layer on a silicon single crystal substrate; (1) Step of forming a V or U# that reaches the silicon single crystal substrate by selective etching: (fA the above V
or a step of oxidizing the surface portion of the U-groove to form an oxide film; 2) a step of filling the aforementioned ■ or U-groove with polycrystalline silicon; and (4) oxidizing the surface portion of the polycrystalline silicon of the gate. Engineering! : In the method of manufacturing a semiconductor device achieved by the method, after the V or U@ formation step, a polycrystalline silicon film r is formed on the surface of the (2) or U groove, and then this polycrystalline silicon film A method for manufacturing a semiconductor device comprising the step of oxidizing a lower epitaxial length layer and a surface portion of a single crystal substrate to form the oxide film.