KR940008321B1 - Semiconductor device isolation method - Google Patents

Abstract

(A) forming the first oxynitride (22) and oxide (23) layers on silicon substrate (21); (B) forming the window by the removal of all of oxide and part of oxynitride layers with photolithography; (C) forming the second oxynitride layer (24) on the substrate; (D) making spacer (25) by dry etching; (E) forming oxide layer (26) by thermal oxidation; (F)removing the oxynitride layer by chemical etching. The other method in the invention comprises the step of etching to the silicon substrate when making window in (B). Another method in the invention comprises the steps of forming the second oxide layer on the whole surface of the substrate after making window, making spacer by dry etching, and removing the layers including the first oxide layer by dry etching.

Description

Device Separation Method of Semiconductor Device

1 (a) to (d) is a manufacturing process diagram showing a conventional device isolation method.

Figure 2 (a) to (d) is a manufacturing process diagram showing a device separation method according to the present invention.

Figure 3 (a) to (d) is a manufacturing process diagram showing an embodiment of the device isolation method according to the present invention.

4 (a) to (d) is a manufacturing process diagram showing another embodiment of the device isolation method according to the present invention.

5 (a) to (d) are manufacturing process diagrams showing another embodiment of the device isolation method according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device isolation method of a semiconductor device, and more particularly, to a device isolation method of a semiconductor device in which device isolation is performed using an oxynitride (SiOxNy) film as a selective oxide mask.

The reduction of the device isolation region separating MOS FETs is one of the important items in MOS miniaturization technology.

In particular, in the large-capacity memory, the device isolation dimension has become a big factor in determining the memory cell size. In the CMOS logic LSI, in order to proportionally shrink the entire chip pattern, the proportional reduction of the element isolation region is inevitable.

The method that has been used in most conventional MOS LSIs as a device isolation technique is a local oxidation of silicon (LOCOS) method and its manufacturing process is shown in FIGS. 1A to 1D.

As shown in FIG. 1A, a thin oxide film 2 is formed on the silicon semiconductor substrate 1, and the nitride film 3 is applied on the oxide film 2, and then the photoresist is formed only in the device formation region. (PR) is applied.

Thereafter, a portion of the nitride film 3 is etched by photolithography to form a region for separation between the elements, thereby forming an opening as shown in FIG.

Next, impurities of the same conductivity type as those of the silicon semiconductor substrate 1 are ion-implanted at high concentration through the opening to form an ion implantation region, and after removing the photoresist PR, in a high temperature furnace. An oxidation process is performed to form a thick field oxide film 4. At this time, the growth of the oxide film is rapidly grown in the portion without the nitride film used as the oxide mask, and the side surface oxidation occurs at the end of the nitride film 3, so that the bird's beak shape, that is, the bird's beak phenomenon occurs. At the same time, the ion implanted impurities are also activated and diffused to form the channel stopper region 6 as shown in FIG.

Finally, as shown in FIG. 1 (d), the semiconductor device regions 7a and 7b where transistors, capacitors, etc. are formed are separated by the final isolation region 8.

However, the formation of the isolation region by the LOCOS method as described above causes the expansion of the beak shape 5 formed in the growth of the field oxide film 4 to the element regions 7a and 7b and the lateral diffusion of the channel stopper region 6. The reduction of the active region of the high density semiconductor device due to the reduction of the element regions 7a and 7b is caused.

In particular, in order to manufacture a semiconductor memory device of megadiram, a manufacturing technique capable of controlling 1 μm is required. The method of forming a separation region as described above is performed when the thickness of the field oxide film 4 is set to a thickness of 3500 GPa or more. The narrowing of the active area becomes a serious problem.

In addition, the LOCOS method does not overcome the limitation of the size of the photo mask, which also causes a reduction in the reduction of the active area, and there is a problem that the LOCOS method cannot be applied to a device requiring high integration due to three-dimensional oxidation.

Accordingly, an object of the present invention is to provide a device isolation method of a semiconductor device that overcomes limitations of the photo mask size to form a small spacer in the device isolation region.

Another object of the present invention is to provide a device isolation method of a semiconductor device that can be applied to a semiconductor device requiring high integration by removing three-dimensional oxidation.

A device isolation method of a semiconductor device for achieving the above object of the present invention is to form an opening by forming a first oxynitride film on a silicon substrate and then etching to a predetermined depth of the first oxynitride film by a photolithography method. Forming a spacer by etching a portion of the substrate to expose the oxide layer as an etch reference plane, forming a spacer, and removing the buffer layer after forming the field oxide layer Characterized in that it comprises a step of forming.

The device isolation method of another semiconductor device for achieving the above object of the present invention is the same as the device isolation method except that the method further comprises the step of forming an oxide film after forming the first oxynitride film on the silicon substrate. It is characterized by consisting of steps.

The device isolation method of another semiconductor device for achieving the above object of the present invention comprises the same steps as the device isolation method except that the silicon substrate is etched to be exposed when etching to a certain depth of the oxynitride film. It features.

Another device isolation method of a semiconductor device for achieving the above object of the present invention comprises the steps of forming an oxynitride film on a silicon substrate, forming a first oxide film on the oxynitride film and a portion of the oxide film by photolithography After etching the second oxide film on the entire surface of the substrate, forming a spacer by the etching method and etching until the first oxide film is removed to recess a portion of the substrate and after forming a field oxide film buffer layer Removing to form a final device isolation region.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

2 (a) to (d) are process diagrams showing the device isolation method of the semiconductor device of the present invention.

Referring to FIG. 2A, a first photonitride film 22 having a thickness of 1500 mW and an oxide film 23 formed by a 120 mW CVD method are sequentially formed on a silicon substrate 21, and then a general photolithography method is performed. To form an opening by etching to the predetermined depth of the oxide film 23 and the oxynitride film 22 formed by the CVD method. At this time, the reason for etching to a certain depth is to reduce the damage occurring during etching.

After that, a second oxynitride film 24 having a thickness of 1500 mW is formed on the entire surface of the substrate as shown in FIG.

Referring to FIG. 2C, the spacer 25 is etched by dry etching using the oxide film 23 formed by the CVD method as an etching reference plane. The silicon substrate is etched to partially expose the etching substrate to form the spacer.

Next, a thermal oxidation process is performed to form a field oxide film, and the oxide layer formed by the oxynitride film and the CVD method is etched and removed by wet etching, followed by separation of the final device as shown in FIG. Region 26 is formed.

Such a device isolation method of the present invention can form a spacer smaller than the limits of the general photo technology, can overcome the three-dimensional oxidation phenomenon and increase the effective device separation length high integration of semiconductor devices in a simple process Can be realized.

A manufacturing process diagram showing an embodiment of the device isolation method according to the present invention is shown in FIGS. 3A to 3D.

In FIG. 3A, after forming the first oxynitride film 32 on the silicon substrate 31 to a thickness of 1500 Å, a predetermined depth of the first oxynitride film 32 is formed by a photolithography method. Etch up to form openings.

Thereafter, a second oxynitride film 33 is formed on the entire surface of the substrate as shown in FIG.

Referring to FIG. 3C, the oxynitride layer 32 is etched using an etching reference plane to form an spacer 34 by using a dry etching method, so that a part of the silicon substrate 31 is exposed. Etch it.

Next, after the thermal oxidation process is performed to form a field oxide film, the oxynitride film 32 is removed by wet etching to form a final device isolation region 35.

4 (a) to (d) are manufacturing process diagrams showing another device isolation method according to the present invention.

As shown in FIG. 4 (a), a 1500-nm-thick oxynitride film 42 and an oxide film 43 formed by a 120-kV CVD method are sequentially formed on the silicon substrate 41, followed by general photolithography. By etching, part of the silicon substrate 41 is exposed to form an opening.

Process steps of FIGS. 4B, 4C, and 3D are the same as those of FIGS. 2B, 4C, and 3D. The present embodiment differs from the device isolation method formed by the second drawings (a) to (d) in that it is etched to the silicon substrate when the opening is formed, as can be seen through the fourth drawing (a). to be. Reference numeral 44 denotes a second oxynitride film, 45 a spacer, and 46 a final device isolation region, respectively.

5 (a) to (d) are manufacturing process diagrams showing another device isolation method according to the present invention.

Referring to FIG. 5A, an oxynitride film 52 having a thickness of 1500 상 에 and a first oxide film 53 formed by CVD are sequentially formed on the silicon substrate 51, and then the photolithography method is performed. A part of the oxide film 53 is selectively etched to form an opening.

Thereafter, as shown in Fig. 5B, a second oxide film 54 formed by CVD is formed on the entire surface of the substrate.

Subsequently, dry etching is performed to form a spacer, and then a portion of the substrate is recessed to a predetermined depth by etching until the first oxide film 53 is removed (FIG. 5C).

Thereafter, a thermal oxidation process is performed to form a field oxide film, and then the oxynitride film 52 is removed by wet etching to form a final device isolation region 55 as shown in FIG. .

As can be seen through various embodiments of the device isolation method according to the present invention, in the selective oxidation method, using an oxynitride film as an anti-oxidation mask to overcome the limitation of the opening size limited by the conventional photolithography method This has the advantage that it is possible to provide smaller spacers that want high integration.

In addition, according to the device isolation method of the semiconductor device of the present invention, since the three-dimensional oxidation phenomenon can be removed, there is an advantage that it can be used in a highly integrated semiconductor device.

Claims (11)

Forming an opening by selectively etching the first oxynitride film after forming the first oxynitride film on the semiconductor substrate; Forming a second oxynitride film on the entire surface of the substrate; Forming an spacer by performing an etching process; And forming a final device isolation region by forming a field oxide film by a thermal oxidation process and then removing the buffer layer formed of the oxynitride film and the oxide film. The method of claim 1, further comprising forming an oxide film after forming a first oxynitride film on the semiconductor substrate. The method of claim 1, wherein the oxide film is formed by a CVD method. The method of claim 1, wherein the spacers are formed by a dry etching method. The method of claim 1, wherein the semiconductor substrate inside the spacer is etched when the second oxynitride layer spacer is formed. 3. The method of claim 1, wherein the etching of the first oxynitride film formed on the semiconductor substrate is performed to expose a predetermined depth or the semiconductor substrate. 2. The method of claim 1 wherein the first and second oxynitride films are each formed at about 1500 microns thick. Sequentially forming an oxynitride film and a first oxide film on a semiconductor substrate, and then etching a portion of the first oxide film by a photolithography process to form openings; Forming a second oxide film on the bottom surface of the substrate; Etching the second oxide layer to form an oxide spacer and then etching the first oxide layer and the oxide spacer until the portion of the semiconductor substrate is removed; And forming a field oxide film through the thermal oxidation process and removing the oxynitride film. The method of claim 8, wherein the first oxide film and the second oxide film are formed by a CVD method. The method of claim 8, wherein the spacers are formed by a dry etching method. 9. The method of claim 8 wherein the oxynitride film is formed to a thickness of about 1500 kPa.