JPH05175330A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce a leakage current path in a diffusion layer of an active region and reduce a leakage current in operation of an active element, by removing a crystal defect of the edge of LOCOS through etching before forming the active element. CONSTITUTION:After forming LOCOS, a crystal defect 4 is generated in an active element forming region 3 of the edge of a LOCOS oxide film 2 in an Si substrate 1. Then, the Si substrate 1 is etched to the depth of the crystal defect 4 and the crystal defect part 4 of the edge of the LOCOS is removed. After removing it, a diffusion layer 5 of an active element is formed. Therefore, the crystal defect 4 of the edge of the LOCOS generated in the diffusion layer 5 of the active element in the case of forming the LOCOS is prevented from being taken in, and a leakage current in operation of the active element can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, it is suitable for reducing a leak current caused by a defect generated on a Si substrate at a LOCOS end which occurs in a semiconductor device using a LOCOS structure as element isolation. It is a thing.

[0002]

2. Description of the Related Art When forming an active element on a Si substrate,
A LOCOS structure is widely used as a method for separating elements.

FIG. 3 shows a cross section of a Si substrate after formation of LOCOS and formation of an active element diffusion layer.

In the figure, 1 is a Si substrate and 2 is a LOCO.
An oxide film in which the Si substrate is selectively oxidized during S formation, 3
Is an active element forming region, and 5 is an impurity diffusion layer formed in the active element region.

[0005]

By the way, the above-mentioned LO
When the substrate is selectively oxidized by heat treatment in the COS structure formation process, the stress acting between the oxide film 2 and the Si substrate 1 disturbs the crystals in the Si substrate, and crystal defects particularly occur at the LOCOS edge. .

Reference numeral 4 in FIG. 3 is a crystal defect generated at the LOCOS edge.

After that, when an active element is formed in the active element formation region 3 and the active element is operated, 4 of crystal defect portions are formed.
There is a problem that a leak current from the diffusion layer 5 to the Si substrate 1 is generated.

[0008]

In order to solve the above-mentioned problems, the present invention removes the crystal defect portion at the LOCOS end by etching the Si substrate after the formation of the LOCOS and before the formation of the active element, and thereafter, the active portion is formed. It is characterized in that an element region is formed.

[0009]

In the above procedure, the crystal defects at the LOCOS end are removed by etching before forming the active element, so that the leak current path in the diffusion layer in the active region can be reduced and the leak current during the operation of the active element can be reduced. it can.

[0010]

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

1 to 2 are sectional views of elements according to the manufacturing flow of an embodiment of the present invention.

FIG. 1 is a sectional view after formation of LOCOS.
In the figure, crystal defects 4 occur in the active element formation region 3 at the end of the LOCOS oxide film 2 in the Si substrate 1.

After the LOCOS is formed, the Si substrate is etched to a depth reaching the crystal defects, and then the diffusion layer 5 of the active element is formed. The sectional view is FIG.

According to the above manufacturing flow, the crystal defect at the LOCOS end generated during the formation of LOCOS is not taken into the diffusion layer of the active element, and the leak current during the operation of the active element can be reduced.

For the etching, a dilute solution of hydrofluoric acid can be used. It is also possible to carry out dry etching such as reactive ion etching.

[0016]

As described above, according to the present invention, by etching the Si substrate after the formation of the LOCOS and before the formation of the active element, the crystal defects generated at the LOCOS edge can be removed and the leak current during the operation of the active element can be reduced.

[Brief description of drawings]

FIG. 1 is an LO for explaining a manufacturing method according to the present invention.
Cross-sectional view of Si substrate after COS formation

FIG. 2 is a cross-sectional view of a Si substrate after the defect portion of the present invention is removed.

FIG. 3 is a sectional view of a Si substrate after conventional LOCOS formation and active element diffusion layer formation.

[Explanation of symbols]

 1 Si substrate 2 LOCOS oxide film 3 active element formation region 4 crystal defect 5 diffusion layer

Claims (2)

[Claims] 1. In a method of manufacturing a semiconductor device that employs a LOCOS structure for element isolation in the process of forming an active element on a Si substrate, defects on the Si substrate generated at the LOCOS edge are formed by the active element formation. A method for manufacturing a semiconductor device, characterized in that it is removed before. 2. The method according to claim 1, wherein S is formed by diluting hydrofluoric acid or reactive ion etching before forming an active element.
A method of manufacturing a semiconductor device, characterized in that a defect at a LOCOS edge is removed by etching an i substrate.