JPH05211230A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To solve the problem of the leakage current increase by a crystal defect and crystal dislocation due to the stress of a bird beak generated at the end section of a LOCOS film through a selective oxidation method and the deterioration of the coverage of a metallic wiring at the end section of the thick LOCOS film at a stroke. CONSTITUTION:An oxide film 2 is formed onto an N-type silicon substrate 1, a thin oxide film 2a is formed and a channel stopper 3 is shaped. The oxide film 2 is removed, and an oxide film 2b is formed. The oxide film 2b is etched while using a resist 4 as a mask, and the resist 4 is removed. An epitaxial layer 5 is grown, and coated with a resist 4a, and the layer 5 and the resist 4a are flattened through etchback.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an element isolation structure for a semiconductor integrated circuit.

[0002]

2. Description of the Related Art A conventional element isolation method using a field oxide film (LOCOS film) by a selective oxidation method will be described with reference to FIGS.

First, as shown in FIG. 2A, an N-type silicon substrate 1 is thermally oxidized at 950 ° C. to form an oxide film 2 having a thickness of 50 nm.

Next, as shown in FIG. 2B, ¹¹ B ⁺ is 1.0 × 10 at 100 keV using the resist 4 as a mask.
^A channel stopper 3 is formed by ion implantation of ¹³ atoms / cm ² .

Next, as shown in FIG. 2C, the thickness 12
After depositing a 0 nm silicon nitride film 9, etching is performed using a resist (not shown) as a mask.

Next, as shown in FIG. 2D, 980 ° C.
Then, it is thermally oxidized to form a LOCOS film 8 having a thickness of 100 nm.

Next, as shown in FIG. 2E, the silicon substrate 1 is etched by etching the silicon nitride film 9.
The active region on the surface is separated by the LOCOS film 8.

[0008]

In the element isolation method using the LOCOS film formed by the selective oxidation method, a thick LOCOS film is locally formed on the surface of the silicon substrate. LO
There is a problem that stress is applied to the silicon substrate near the edge of the COS film (hereinafter referred to as bird's beak), crystal defects and crystal dislocations occur, and leak current increases.

Further, since there is a step between the region where the element is formed and the separation band where the LOCOS film is formed, there is a problem that the step coverage of the metal wiring connected to the element is poor.

[0010]

According to a method of manufacturing a semiconductor device of the present invention, a step of forming an insulating film for element isolation on a main surface of a semiconductor substrate and then performing selective etching, and growing an epitaxial layer on the entire surface. And a step of applying a resist on the entire surface and then etching back to flatten it.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to (g).

First, as shown in FIG. 1A, the N-type silicon substrate 1 is thermally oxidized at 980 ° C. to form an oxide film 1 having a thickness of 500 nm.

Next, as shown in FIG. 1B, the oxide film 2 is etched by using a resist (not shown) as a mask, and then thermally oxidized again at 950 ° C. to form the oxide film 2 having a thickness of 40 nm.
a is formed. The oxide film 2a suppresses surface damage of the silicon substrate 1 due to ion implantation.

Next, using the oxide film 2 as a mask, 1 1 of ¹¹ B ⁺ is added.
1.2 × 10 ¹³ atoms / cm ² ions are implanted at 00 keV to form a channel stopper 3 made of a P ⁺ type diffusion layer.

Next, as shown in FIG. 1C, the oxide film 2
After removing the entire surface, it is thermally oxidized at 980 ° C to a thickness of 1000.
An oxide film 2b having a thickness of 2 nm is formed.

Next, as shown in FIG. 1D, the oxide film 2b is etched using the resist 4 as a mask.

Next, as shown in FIG. 1 (e), the resist 4 is removed, and an N-type silicon epitaxial layer 5 having a thickness of 1.5 μm is grown by the CVD method and then annealed to single crystal.

Next, as shown in FIG. 1F, a resist 4a is applied.

Next, as shown in FIG. 1G, the active region 7 surrounded by the isolation region 6 made of the oxide film 2b is formed by the etch back method.

The same effect can be obtained by using any one of an N type epitaxial layer, a P type silicon substrate and a P type epitaxial layer in place of the N type silicon substrate used in this embodiment.

[0021]

EFFECTS OF THE INVENTION An insulating film for element isolation is formed, an epitaxial layer is grown, and then etched back to be flattened.

As a result, compared to the LOCOS separation method, there is no bird's beak and stress on the semiconductor substrate is eliminated. It is possible to prevent an increase in leak current due to crystal defects and crystal dislocation, which has been conventionally caused by stress.

Further, since the surface is flattened by the etch back method, the step between the active region for element formation and the insulating film for element isolation is eliminated. The step coverage of the metal wiring connected to the device is significantly improved as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention in the order of steps.

FIG. 2 is a cross-sectional view showing isolation between elements by a conventional selective oxidation method.

[Explanation of symbols]

 1 N-type silicon substrate 2, 2a, 2b oxide film 3 channel stopper 4, 4a resist 5 epitaxial layer 6 isolation region 7 active region 8 LOCOS film 9 silicon nitride film

Claims (1)

[Claims] 1. A step of forming an insulating film for element isolation on a main surface of a semiconductor substrate and then performing selective etching, a step of growing an epitaxial layer on the entire surface, and a step of applying a resist on the entire surface and then etching back. And a method of manufacturing a semiconductor device, the method including the step of planarizing.