JPS6243146A - Manufacture of semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To prevent breakdown of a metal wiring at a step on a main surface, by forming a silicon growing layer on the main surface of a semiconductor substrate having a dielectric isolating structure, then performing thermal oxidation, thereby eliminating the step on the main surface on the isolated silicon oxide film. CONSTITUTION:A silicon growing layer 15 is formed on the main surface of a semiconductor substrate 10 having a dielectric isolating structure. The silicon growing layer 15 is oxidized by a thermal oxidation method, and an oxide film 16 is formed. Then, the silicon oxide film 16 is selectively removed by etching, and a part of a single crystal silicon island 14 is exposed. Thereafter, impurities are diffused in the exposed surface of the single crystal silicon by a selective diffusing method, and impurity diffused region 17 is formed. Then, a metal wiring 18 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor integrated circuit having a dielectric isolation structure, and particularly to a method for manufacturing a semiconductor integrated circuit that requires a high breakdown voltage.

[Prior art] Conventionally, this type of semiconductor integrated circuit is
) was manufactured using the process. That is, Fig. 2 (a
＞A second semiconductor substrate 20 having a V dielectric isolation structure shown in FIG.
As shown in the figure (+), the main surface is oxidized to form a silicon oxide film 25. This silicon oxide film 25 has a zero-order second
As shown in Figure (C), a portion of the silicon oxide film is etched to expose the surface of the single crystal silicon island 24. Next, as shown in FIG. 2(d), impurities are diffused into the exposed surface of this single crystal silicon by the A-type diffusion method to form impurity diffusion regions 26, circuit elements are formed, and metal is placed between the circuit elements. Apply wiring 27.

[Problem that the invention seeks to solve]

In the conventional semiconductor integrated circuit manufacturing method described above, as shown in FIG. Since the film 25 is much thinner than the pond portion, depressions 28 are formed in the surface silicon oxide film. Therefore, there was a drawback that the metal wiring was easily broken in this part 9).

The present invention eliminates the drawbacks of the conventional methods described above, eliminates the level difference on the main surface of the isolation silicon/oxide film, and provides a semiconductor device having a dielectric isolation structure that can prevent the metal wiring from breaking at this location. The purpose is to provide a manufacturing method for.

[Means for solving problems]

A semiconductor integrated circuit manufacturing method of the present invention includes a semiconductor device in which a plurality of single crystal silicon islands are embedded in polycrystalline silicon via a first silicon oxide film, and one surface of the single crystal silicon islands is exposed. A step of forming a silicon growth layer on the main surface of the substrate, a step of changing the silicon growth layer into a second silicon oxide film by a thermal oxidation method, and a step of selectively removing the second silicon oxide film by means of an etching process. The method is comprised of a step of exposing one surface of the single crystal silicon island, and a step of diffusing impurities into the single crystal silicon island from the main surface side of the double-conductor substrate by a selective diffusion method to form a circuit element. Ru.

[Example, 1 Next, the present invention will be explained with reference to FIG. 3.

FIGS. 1(a) to 1(d) are cross-sectional views shown in the order of steps for explaining an embodiment of the present invention.

First, as shown in FIG. 1(a), a silicon growth layer 15 is formed on the main surface of a semiconductor substrate 10 having a dielectric isolation structure.

In the figure, 11 is polycrystalline silicon supporting the single crystal silicon island 14, 12 is an isolation silicon oxide film, and 13 is a high concentration buried layer.

Next, as shown in FIG. 1(b), the silicon growth N15 is oxidized by a thermal oxidation method to form a silicon oxide film 16.

Next, as shown in FIG. 1(c), the silicon oxide film 16
is selectively removed by machining and soching to form single crystal silicon island 1.
Expose part of 4.

Next, as shown in FIG. 1 ((1)), impurities are diffused into the exposed surface of this single crystal silicon by a selective diffusion method to form an impurity diffusion region 17, and then a metal wiring 18 is formed. A semiconductor integrated circuit having a dielectric isolation structure according to the example is completed.

(Effects of the Invention) As explained above, the present invention is capable of forming a silicon growth layer on the main surface of a semiconductor substrate having a dielectric isolation structure, and then forming a film.
The fi formation eliminates the level difference on the main surface of the isolation silicon oxide film and has the effect of preventing the metal wiring from breaking at this location.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(d) are cross-sectional views shown in order of steps to explain an embodiment of the present invention, and FIGS. 2(a) to 2(d) are sectional views of a conventional dielectric material i! FIG. 3 is a cross-sectional view shown in order of steps to explain an example of a method for manufacturing a semiconductor integrated circuit having an if structure. 10.20... Semiconductor substrate with dielectric isolation structure, 11.
21... Polycrystalline silicon, 12.22... Isolated silicon oxide film, 13.23... High concentration buried layer, 14゜2
4... Single crystal silicon island, 15... Silicon growth layer, 16.25... Silicon oxide film, 17.26...
Impurity diffusion region, 18.27... Metal wiring, 28...
- Hollow silicon oxide film. Agent Patent Attorney Uchihara Mukashi α 〈 8 l Diagram No. 2

Claims (1)

[Claims] A plurality of single-crystal silicon islands are embedded in polycrystalline silicon via a first silicon oxide film, and a silicon growth layer is formed on the main surface of the semiconductor substrate where one surface of the single-crystal silicon islands is exposed. a step of changing the silicon growth layer into a second silicon oxide film by a thermal oxidation method;
selectively removing the silicon oxide film by etching to expose one side of the single crystal silicon island, and diffusing impurities into the single crystal silicon island from the main surface side of the semiconductor substrate by a selective diffusion method to form a circuit element. A method for manufacturing a semiconductor integrated circuit, comprising the steps of: