JPS63257244A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent an insulator from sinking below the surface of a semiconductor substrate by forming a device isolation region in such a way that the insulator filled in a groove is projected from the surface of the semiconductor substrate. CONSTITUTION:An insulator 5 is filled in a groove 2 and is formed by a CVD oxide film. The insulator 5 is projected from the surface of a silicon substrate 1 by, e.g., about 1000-5000 Angstrom . The height of this protrusion of the insulator 5 is set appropriately in such a way that the insulator 5 does not sink below the surface of the silicon substrate 1 after an operation to be executed during a subsequent device formation process. By this setup, even when the insulator 5 is etched to some extent by a subsequent etching operation, the insulator 5 does not sink below the surface of the silicon substrate 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor device in which elements are separated by an insulator and a method for manufacturing the same, and particularly relates to a semiconductor device in which elements are isolated by an insulator and a method for manufacturing the same. The present invention relates to a semiconductor device including an element isolation region and a method for manufacturing the same.

[Conventional technology]

FIG. 3 fat is a sectional view showing the structure of such a conventional semiconductor device.

In the figure, 1 is a silicon substrate, 2 is a groove formed on a silicon base Fi,l to separate the element regions A and B, and 3 is a groove 2 formed so as to be almost flush with the surface of the silicon substrate 1. It is an embedded insulator. As the insulator 3, for example, CVD (Chemical Vapor
Deposition) An oxide film is used.

Next, a method of manufacturing the above-mentioned conventional semiconductor device will be explained with reference to FIG.

Groove portions 2 are formed on silicon substrate 1 to separate element regions A and B (see FIG. 4 fa). A CVD oxide film 3. is formed on the silicon substrate 1 in which the groove portion 2 is formed. (This CV
D oxide 1123 (which will eventually become the insulator 3 shown in FIG. 3) is deposited, and this CVD oxide film 3. Fill the groove 2 with (see Fig. 4 mountain)).

CVD oxide film 3. The photoresist 4 is coated thickly on the silicon substrate 1 on which the CVD oxide film 3. is deposited (see FIG. 4(C)), and the photoresist 4 and the CVD oxide film 3. Etch it flat. In this way, an element isolation region in which the insulator 3 is embedded in the trench 2 as shown in FIG. 3 is formed. Although omitted in the explanation of the manufacturing method described above, before embedding the CVD oxide film 31, treatments such as implanting boron for channel oxidation into the trench 2 and forming a thermal oxide film are performed as appropriate. There is.

[Problem that the invention seeks to solve]

However, in the conventional semiconductor device, since the insulator 3 embedded in the groove 2 is substantially on the same plane as the surface of the silicon substrate 1, the element formation process is performed after the element bone i%I tiI region is formed. This causes the following problems.

For example, in the step of forming a gate or the remaining oxide film etching process, etching treatment using diluted hydrogen fluoride or ammonium fluoride is performed. Since the etching rate of the etching solution is faster than that of the thermal oxide film (not shown) formed on the silicon substrate 1 during the device formation process, the CVD oxidation process is faster as shown in FIG. The film 3I falls below the surface of the silicon substrate 1, and
Since the step of the groove 2 created in this way is steep, when forming gate electrodes and wiring later, residues of gate electrode material and wiring material (etching residue) are left along the step.
This tends to cause problems such as short circuits between adjacent wirings.

This invention has been made to solve these problems, and is aimed at preventing etching residue from being generated at the boundary between the trench where the insulator is buried and the surface of the silicon substrate when forming gate electrodes and wiring. The purpose is to provide a highly sophisticated semiconductor device and its manufacturing method.

[Means for solving problems]

In the semiconductor device according to the present invention, an insulator that is buried in a groove for element isolation formed in a semiconductor substrate to form an element isolation region protrudes from the surface of the semiconductor substrate.

Further, in the method for manufacturing a semiconductor device according to the present invention, a first insulating film is deposited on a semiconductor substrate, a trench for element isolation is formed in the semiconductor substrate through the first insulating film, and the first insulating film is formed in the trench. After depositing a second insulating film of a different type from the first insulating film so as to embed it, the second insulating film is deposited from the surface of the semiconductor substrate on which the second insulating film is deposited, so that the surface of the semiconductor substrate on which the second insulating film is deposited is flat. After gradually removing the semiconductor substrate and stopping the removal process when the lower first insulating film is reached, the first insulating film is removed to expose the surface of the semiconductor substrate.

[Effect]

In this invention, the insulating material embedded in the groove is made to protrude beyond the surface of the semiconductor substrate to form the element isolation region, so even if the insulating material is etched to some extent by the later etching process, the insulating material remains on the surface of the substrate. I'm never more depressed than I am. Moreover, the edges of the insulator protruding from the substrate surface are smoothed by the etching process, making it difficult for etching residues to form during the process of forming gate electrodes and wiring.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view schematically showing the structure of a semiconductor device showing the structure of an embodiment of the present invention.

In this figure, the same reference numerals as those in the conventional example shown in FIG. 3 indicate the same parts, so the explanation here will be omitted.

In FIG. 1, 5 is an insulator embedded in the groove 2. As shown in FIG. This insulator 5 is formed of, for example, a CVD oxide film, as in the case of the conventional example described above. This insulator 5 is, for example, 1000 to
The protruding height of the insulator 5 is about 5,000 people.
The etching process performed in the subsequent element forming step will appropriately set the height of the insulator 5 to such an extent that it will not fall below the surface of the silicon substrate 1.
It is not limited to the above range.

Since the insulator 5 is made to protrude above the surface of the silicon substrate 1 in this way, even if the insulator 5 is etched to some extent in the subsequent etching process, the insulator 5 will not fall below the surface of the silicon substrate 1. Moreover, since the edges of the insulator 5 are smoothed by the etching process, the edges of the insulator 5 are smoothed. Etching residues are less likely to be generated during etching in the IT electrode and wiring formation process.

Next, a method for manufacturing the above-mentioned semiconductor device will be explained with reference to FIG.

On the Cal silicon substrate 1, there is a thin thermal oxide film 6 with a thickness of, for example, several hundred layers, and a thin thermal oxide film 6 with a thickness of, for example, several hundred layers as a first insulating film.
A relatively thick nitride film 7 and a film to be used as a mask when etching the silicon substrate 1, for example, a CVD oxide film 8, are formed in that order (see FIG. 2 (al)).Thermal oxide film 6 When the nitride film 7 is removed later, the silicon base vi
, 1 is provided to protect the surfaces of the parts. Therefore, if damage to the silicon substrate 1 when removing the nitride film 7 is not a problem, there is no need to form the thermal oxide film 6.

(The thermal oxide film 6 is formed by BL photolithography,
Nitride film? , the CVD oxide film 8 is etched to form a window at the location where the groove will be formed (see FIG. 2(b)).

(c) Using the opened CVD oxide film 8 as a mask, a groove 2 is formed in the silicon substrate 1 by anisotropic ion etching (RIE) (see FIG. 2(C)).

fdl CVD oxidation [8] After removing the CVD oxide film 5.fdl, for example, a CVD oxide film 5. (This CVD oxide film 51 will eventually become the insulator 5 shown in FIG. 1) is deposited, and the trench 2 is filled with this CVD oxide film 51 (see FIG. 2 [dl]).

In order to prevent the depression of the tel groove 2 from appearing on the surface as much as possible, a CVD oxide film 5. A thick layer of photoresist 9 is applied over the photoresist (see FIG. 2 (81)).

fflThe photoresist 9 and the CVD oxide film 51 are plasma etched flatly so that the photoresist 9 and the CVD oxide film 51 are etched at approximately the same speed, and when the nitride film 7 is reached, the etching process is performed. Stop (see Figure 2 (fl)).

Here, CVD oxide film 5. By appropriately setting the mixing ratio of the oxygen gas for photoresist etching, which is mixed with the gas for etching the photoresist 9 and the CVD oxide film 5. It is possible to make the etching speed almost the same. Furthermore, when the etching reaches the nitride film 7, the nitride film 7 is slightly etched and nitrogen gas is released, so by detecting this nitrogen gas, it can be confirmed that the etching has reached the nitride film 7. You can know.

[+The nitride film 7 is removed by hot phosphoric acid or plasma etching (see FIG. 2(a)).

[hl] Furthermore, the thermal oxide film 6 is etched to expose the surface of the silicon substrate 1 (see FIG. 2 (hl)).

Thereby, the insulator 5 protruding from the surface of the silicon substrate 1 can be obtained as shown in the figure.

However, since the insulator 5 can be made to protrude from the surface of the silicon substrate 1 by removing the nitrided IPJ 7, the removal of the thermal oxide film 6 is not necessarily necessary.

After forming the element isolation regions as described above, elements are formed in each element region.

In addition, in the above-mentioned embodiment, the CVD buried in the groove part 2
Oxide film 5. Although the nitride film 7 is used to stop the etch-back in the middle, a non-doped polycrystalline silicon film or the like may also be used.

Further, in the above embodiment, the photoresist 9 and the CVD oxide film 5. Plasma etching was used as a means to flatten the photoresist 9 and the CVD oxide film 5. by polishing, for example. It may also be a method that flatly removes the .

〔Effect of the invention〕

As described above, according to the semiconductor device according to the present invention, since the insulator buried in the trench for element isolation is made to protrude from the surface of the semiconductor substrate, the element formation process after the element part 'f=HeM region is formed. Even if the insulating material is etched to some extent in the etching process performed in the etching process, the insulating material does not fall below the surface of the semiconductor substrate.

Moreover, since the edges of the insulator are smoothed by the etching process, the gate electrode material and wiring material are less likely to remain at the interface between the insulator and the semiconductor substrate surface during etching to form gate electrodes and wiring. This makes it possible to improve the manufacturing yield and reliability of semiconductor devices.

Further, according to the method for manufacturing a semiconductor 4A device according to the present invention, the above-described semiconductor device can be easily realized.

[Brief explanation of the drawing]

10 is a sectional view schematically showing the configuration of an embodiment of a semiconductor device according to the present invention, FIG. 2 is an explanatory diagram of an embodiment of the method for manufacturing a semiconductor device according to the present invention, and FIG. 3 is a conventional example. FIG. 4 is a cross-sectional view schematically showing the structure of a semiconductor device, and FIG. 4 is an explanatory diagram of a conventional method of manufacturing a semiconductor device. In the figure, number 1 is silicon base seven, number 2 is number 18, number 5 is
51 is an insulator, 51 is a CVD oxide film, and 7 is a nitride film. Note that the same reference numerals in the figure indicate the same or equivalent 05 minutes.

Claims (2)

[Claims] (1) A semiconductor device including an element isolation region in which an insulator is embedded in an element isolation groove formed in a semiconductor substrate, wherein the insulator is made to protrude beyond the surface of the semiconductor substrate. Device. (2) a step of depositing a first insulating film on a semiconductor substrate; a step of forming a trench for element isolation in the semiconductor substrate through the first insulating film; and a step of depositing a first insulating film on the semiconductor substrate; a step of depositing a second insulating film so as to embed the second insulating film;
The method is characterized by comprising the steps of: gradually removing the insulating film from the surface thereof and stopping the removal process when reaching the underlying first insulating film; and removing the first insulating film. A method for manufacturing a semiconductor device.