KR0148297B1 - Method for isolating semiconductor devices - Google Patents

Abstract

In the isolation method between semiconductor devices according to the present invention, in order to solve the problems caused by the bead buckling phenomenon and the narrow width effect, and the problem of misalignment between the impurity layer and the isolation layer in the substrate, the self-aligned chemistry of the After the vapor deposition oxide film is formed, the chemical vapor deposition oxide film is etched to remain only in the device isolation region to form an isolation film to isolate the semiconductor devices, thereby facilitating high integration of the semiconductor integrated circuit.

Description

Isolation Method between Semiconductor Devices

1 is a view showing a method of forming a local oxide film, which is a method of isolation between conventional semiconductor devices.

2 is a view showing a method of forming a chemical vapor deposition oxide film as a method of isolation between conventional semiconductor devices.

3 is a diagram showing a method for isolating semiconductor devices according to the present invention.

* Explanation of symbols for main parts of the drawings

10.20.30: semiconductor substrate 11: oxide film

12: nitride film 13: local oxide film

21.31 Separator 22.32 Lateral oxide

23: photoresist A.A'.A: device isolation region

B.B'.B: device formation area

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of isolation between devices in a semiconductor integrated circuit, and more particularly, to a method of isolation between semiconductor devices suitable for high integration of devices using chemical vapor deposition oxide films of a self-aligning method.

In semiconductor integrated circuits, isolation between the devices has a great influence on the operation of each device and the high integration of the integrated circuits.

Conventionally, the isolation method between semiconductor devices is made of a local oxide film formed by LOCOS (Local Oxidation of Silicon), or a chemical vapor deposition (CVD) oxide film is used.

FIG. 1 is a diagram showing a method of forming a local oxide film, which is a isolation method between conventional semiconductor devices, and FIG. 2 is a diagram showing a method of forming an isolation film using a chemical vapor deposition oxide film, which is a isolation method between conventional semiconductor devices. Referring to the drawings, the isolation method between the conventional semiconductor devices is as follows.

As a method of isolating each element in a conventional semiconductor integrated circuit, a method of forming a local oxide film has been used, as shown in FIG.

In order to form a local oxide film on a semiconductor substrate, first, an oxide film 11 and a nitride film 12 are sequentially deposited on the semiconductor substrate 10, and then, as shown in FIG. 1A, an oxide film on the semiconductor substrate 10 is formed. (11) and the nitride film 12 are removed to define the device isolation region A and the device formation region B. In FIG.

As shown in FIG. 1B, ion-implanted impurities, such as a substrate, are implanted into the device isolation region B using the nitride film 12 of the element formation region B as a mask on the semiconductor substrate 10.

Thereafter, as shown in FIG. 1C, a local oxide film 13 is formed by growing an oxide film of a predetermined thickness or more in the device isolation region.

In this case, in a device isolation region in which a local oxide film is formed on a semiconductor substrate, a threshold voltage is increased, so that electrons do not move to the surface of the substrate under the local oxide film between adjacent devices. In order to further increase the threshold voltage at the limited local oxide thickness condition, as shown in FIG. 1B, an impurity layer for channel stop is formed by ion implantation of an impurity of a conductive type such as a substrate.

That is, in the isolation method between devices by local oxide, the nitride film on the semiconductor substrate can completely separate the device formation region and the device isolation region during the formation of the local oxide film.

As the integration degree of the semiconductor integrated circuit increases, the device formation region is reduced by a bird's beak phenomenon in which both edges of the local oxide film penetrate the side of the device formation region, and isolation between the devices is achieved. A problem arises in that a narrow width effect occurs in which the threshold voltage of each device formed in the device formation region is increased by the side diffusion of the impurity ion layer under the local oxide film.

In addition, when a device isolation region having a width of 1 μm or less is formed between elements on a semiconductor substrate, an oxide thinning effect in which the thickness of a local oxide film formed by growing and forming an oxide film in the device isolation region becomes smaller than a desired thickness. Occurred.

Another isolation method between semiconductor devices, which has been used to solve this problem of the isolation method between devices by local oxides in the isolation method between semiconductor devices, is a device isolation using a chemical vapor deposition oxide film as shown in FIG. Way.

In order to form a chemical vapor deposition oxide film on a semiconductor substrate, first, as shown in FIG. 2A, the device formation region B 'and the device isolation region are formed on the semiconductor substrate 20 using a photoresist 23. After defining (A '), ion implantation is selectively implanted into the device isolation region A' such as a conductive type impurity such as the semiconductor substrate 20.

As shown in FIG. 2B, the photoresist 23 on the surface of the element formation region B 'is removed from the semiconductor substrate 20.

Subsequently, an oxide film is chemically deposited on the entire surface of the semiconductor substrate 20 to form a chemical vapor deposition oxide film, and photochemically etched on the entire surface of the semiconductor substrate 20 to leave the chemical vapor deposition oxide film only in the device isolation region A 'to form the isolation film 21. Further, the oxide film was further subjected to chemical vapor deposition and dry etched to form side oxide films 22 on both sides of the isolation film 21 on the device isolation region A 'as shown in FIG.

In the conventional method for isolating semiconductor devices by chemical vapor deposition oxide film, problems such as the buzz beak phenomenon and the narrow width effect of the device isolation method by local oxide film can be improved.

That is, in the device isolation method using a local oxide film and the device isolation method using a chemical vapor deposition oxide, which are conventional device isolation methods, in the device isolation method using a local oxide film, the width of the device formation region is reduced and the threshold voltage of each device is increased. In the device isolation method using the chemical vapor deposition oxide film, the problem of device isolation by the local oxide film was solved, but the misalignment between the impurity layer in the substrate and the chemical vapor deposition oxide film on the substrate surface was solved. (Ⓑ) was generated, and the impurity layer in the device isolation region had to be sufficiently encapsulated by the chemical vapor deposition oxide film, which made it difficult to apply the semiconductor integrated circuit.

The isolation method between semiconductor devices according to the present invention was devised to solve such a problem, and its object is to facilitate high integration of semiconductor integrated circuits by isolating semiconductor devices using chemical vapor deposition oxide films of a self-aligning method. .

The isolation method between semiconductor devices according to the present invention comprises the steps of forming an impurity layer by ion implanting an impurity of a conductive type such as a substrate on the surface of the semiconductor substrate, and chemical vapor deposition of a first oxide film on the entire surface of the semiconductor substrate on which the impurity layer is formed. And forming an isolation layer defining an element formation region by etching the residue to remain only in the device isolation region on the semiconductor substrate, and chemically vapor-depositing and etching back the second oxide layer over the entire surface of the semiconductor substrate to form side oxide layers on both sides of the separator. And forming ion-implanted impurities of the opposite type to the semiconductor substrate using the isolation layer and the side oxide film on the device isolation region as a mask to offset the impurity layer of the device formation region.

3 is a view showing an example of an isolation method between semiconductor devices according to the present invention, an example of the isolation method between semiconductor devices according to the present invention with reference to the drawings as follows.

First, as shown in FIG. 3A, in order to increase the threshold voltage of the device isolation region that isolates the devices from the surface of the semiconductor substrate 30, ion-implanted impurities such as the semiconductor substrate 30 are ion implanted.

As shown in FIG. 3 (b), after the first oxide film is chemically deposited on the entire surface of the semiconductor substrate 30 to form a chemical vapor deposition oxide film, the device formation region B is formed on the semiconductor substrate 30 by a dry etching process. ) And the chemical vapor deposition oxide film is left only on the device isolation region (A) to form the isolation film (31). In the exemplary embodiment of the present invention, the chemical vapor deposition oxide film is dry-etched to form the separator 31. However, in another embodiment of the present invention, the chemical vapor deposition oxide film may be wet-etched to form the separator 31.

Thereafter, in order to reduce the difficulty of the semiconductor device manufacturing process due to the step generated by the device isolation region A formed by dry etching on the semiconductor substrate 30, the second oxide film is chemically vapor deposited and etched back to isolate the separator. The side oxide film 32 is formed on both sides of the 31.

Subsequently, as shown in FIG. 3 (c), the impurity layer of the element formation region B is implanted by ion implanting impurities of the opposite conductivity type into the semiconductor substrate 30 using the isolation layer 31 of the element isolation region A as a mask. Offset.

In the present invention, an isolation film formed by dry etching a self-aligned chemical vapor deposition oxide film on a semiconductor substrate is formed in the device isolation region to isolate semiconductor devices.

In the isolation method between semiconductor devices according to the present invention, the reduction of the channel width of the device formation region due to the Buzz Beek phenomenon caused by the local oxide film, which is a conventional isolation method between semiconductor devices, and the isolation of the device at the time of forming the local oxide film The diffusion of the impurity layer in the region can reduce the threshold voltage increase of each element formed in the element formation region and can eliminate the misalignment in the isolation method between semiconductor elements by chemical vapor deposition oxide film. The isolation between the elements can be easily performed.

Claims (2)

A method of isolating semiconductor devices, comprising the steps of: 1) implanting an impurity layer, such as a substrate, into an impurity layer on a surface of a semiconductor substrate; and 2) a first oxide film on the entire surface of the semiconductor substrate on which the impurity layer is formed. Chemical vapor deposition and etching so as to remain only in the device isolation region on the semiconductor substrate to form an isolation film defining a device formation region; and 3) chemically vapor deposition and etch back a second oxide film on the entire surface of the semiconductor substrate; Forming side oxide films on both sides of the semiconductor substrate; and 4) canceling the impurity layer of the device forming region by ion implanting impurities of the opposite type to the semiconductor substrate using the isolation layer and the side oxide film on the device isolation region as masks. Isolation method between the semiconductor device comprising a. The method of claim 1, wherein in the step 2), the first oxide layer on the semiconductor substrate is dry-etched.