KR100548574B1 - Method of manufacturing semiconductor device - Google Patents

Abstract

The present invention discloses a method of fabricating a semiconductor device for forming an active region and a device isolation film using a silicon epitaxial growth process. A method of manufacturing a semiconductor device according to the present invention, comprising: growing a field oxide film on a silicon substrate; Etching the field oxide layer to form a trench to expose a substrate active region; Growing a silicon film on the substrate surface exposed by the trench at a height lower than that of a field oxide film according to a silicon epitaxial growth process; Coating a photoresist film on the silicon film and the field oxide film; And chemically mechanically polishing the photoresist film and the field oxide film including the upper portion of the silicon film to expose the silicon film to form an active region and a device isolation film.

Description

Method of manufacturing semiconductor device

1A and 1B are cross-sectional views illustrating a method of forming a device isolation film using a conventional silicon epitaxial growth process.

2A through 2E are cross-sectional views of processes for describing a method of manufacturing a semiconductor device, according to an embodiment of the present invention.

3 is a cross-sectional view illustrating a method of manufacturing a semiconductor device in accordance with another embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

21 silicon substrate 22 field oxide film

23 trench 24 silicon film

25 photosensitive film 30 active region

32: device isolation film

The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of forming an active region and a device isolation film using a silicon epitaxial growth process.

Insulation between individual cells of a semiconductor memory device is currently progressing through a shallow trench isolation (STI) process. In addition, in order to overcome the reduction of the refresh time caused by the miniaturization of the device in the STI process, a technique of forming a linear nitride film before deposition of the trench buried oxide film has been introduced.

Hereinafter, a device isolation film forming method according to a conventional STI process will be briefly described.

First, a pad oxide film and a pad nitride film are sequentially formed on a substrate, and then the pad nitride film is etched to define a region where the device isolation film is to be formed. Then, using the pad nitride film as an etching mask, the pad oxide film and the substrate are etched to form trenches.

The thermal oxide is then grown to prevent cell to cell leakage and junction leakage current, and then surface attack that can occur during subsequent HDP-CVD oxide deposition. A thin film of linear nitride is deposited to suppress.

Then, after depositing a linear oxide film on the linear nitride film, an HDP-CVD oxide film is deposited to fill the trench. Here, since the stress properties of the linear nitride film and the HDP-CVD oxide film are opposite to each other, defects in the form of bubbles may occur when directly contacted. Therefore, in order to prevent the occurrence of such bubble defects, the linear oxide film is interposed between the linear nitride film and the HDP-CVD oxide film.

Next, the mechanical mechanical polishing (CMP) of the HDP-CVD oxide film is performed, and then the pad nitride film is removed to complete the formation of the device isolation film.

However, the device isolation film forming method using the STI process described above uses a double layer as a linear material, and in particular, the nitride film is deposited on the back surface of the wafer in connection with the deposition of the linear nitride film by the FLP (Furnace Low Pressure) -CVD process This increases the dipping time in phosphoric acid (H3PO4) upon subsequent removal of the pad nitride film, which in turn is a major cause of deterioration of moat properties.

In addition, the actual thickness of the nitride / oxide layer structure used as the linear material is partially thinly deposited due to the loading effect so that it is not able to withstand the damage caused by plasma during the deposition of the subsequent HDP-CVD oxide layer. As a result of this phenomenon, the mote becomes larger and the effect of improving the refresh characteristics of the device expected is removed.

As a result, as the degree of integration of semiconductor devices increases, the cell threshold voltage drop and hump phenomenon caused by the deepening of motes, bridges due to residues during gate etching, and the like can be solved, thereby improving the refresh characteristics of semiconductor devices. There is a growing demand for device isolation processes.

On the other hand, as another conventional technique that can improve the above problems has been proposed a casting device isolation film forming method. The casting device isolation film forming method is as follows.

First, as shown in FIG. 1A, after growing the field oxide film 2 on the silicon substrate 1, the field oxide film portion to be the active region is removed through a masking and etching process.

Then, as illustrated in FIG. 1B, the silicon film 3 is deposited by a Si epitaxial growth (SEG) process on the substrate active region from which the field oxide film 2 is removed.

Subsequently, although not shown, the surface of the silicon film 3 is CMP so that the field oxide film 2 is exposed, thereby completing the device isolation structure.

However, in the method of forming a cast-type device isolation layer using the SEG process, the active region and the device isolation layer are defined by the CMP process after the active region is completely filled, and therefore, it takes a long time to grow silicon, and thus, in terms of productivity Not desirable

The time required for the silicon growth time is that the silicon film must be thicker than the oxide film for device isolation in order to completely fill the active region.

Accordingly, an object of the present invention is to provide a method of manufacturing a semiconductor device that can reduce the silicon growth time while using the SEG process, which has been devised to solve the conventional problems as described above.

Method of manufacturing a semiconductor device according to the present invention for achieving the above object comprises the steps of growing a field oxide film on the entire surface of the silicon substrate; Etching the field oxide layer to expose the active region of the silicon substrate to form a trench; Epitaxially growing a silicon film in the trench with the silicon substrate as a seed so that an upper surface thereof has a lower height than an upper surface of the field oxide film; Coating a photoresist film on the silicon film and the field oxide film; And chemically polishing the photosensitive film and the field oxide film including an upper portion of the silicon film to expose the silicon film, thereby defining an active region and a device isolation region.

Here, the field oxide film is grown to a thickness of 2000 ~ 5000Å, the field oxidation process for forming the field oxide film is any one of dry, wet, or dry and wet mixing method at a temperature of 900 ~ 1175 ℃. Perform. In addition, the field oxidation process for forming the field oxide film is performed by adding TCA or HCl to control contamination by metallic impurity.

Performing H2 baking and HF steaming to remove the native oxide film on the substrate surface exposed by the trench after forming the trench and before growing the silicon film, wherein the H2 baking Is performed at 700 to 1200 ° C. for at least 10 seconds, and the HF vapor treatment is performed at 25 seconds or less.

The growth of the silicon film according to the silicon epitaxial growth process is performed using a mixed gas of DCS, HCl, H2 or Si2H4, Cl as a source, the temperature is 700 ~ 1200 ℃, the base pressure of the equipment 10E-6 ~ 10E- A low pressure of 8 Torr and a process pressure of -10E-5 Torr were carried out, and the silicon film was grown to a thickness corresponding to 50 to 95% of the thickness of the field oxide film.

In addition, the present invention comprises the steps of growing a field oxide film on the entire surface of the silicon substrate; Etching the field oxide layer to expose the active region of the silicon substrate to form a trench; Removing the native oxide film on the surface of the silicon substrate exposed by the trench by H2 baking and HF steam treatment; Epitaxially growing a silicon film in the trench with the silicon substrate as a seed so that an upper surface thereof has a lower height than an upper surface of the field oxide film; Coating a photoresist film on the silicon film and the field oxide film; Defining an active region and an isolation region by chemical mechanical polishing of the photoresist layer and the field oxide layer with a target of stopping at an upper portion of the silicon layer; And removing the photoresist film remaining on the silicon film.

Here, the field oxide film is grown to a thickness of 2000 to 5000 microns, and the silicon film is grown to a thickness corresponding to 50 to 95% of the thickness of the field oxide film.

(Example)

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

First, the technical principle of the present invention will be described.

In the present invention, in forming a cast device isolation layer using a SEG process, a silicon film is grown to a thickness lower than that of a field oxide film, and then a photosensitive film is coated on the silicon film and the field oxide film, and then, until the silicon film is exposed. The photosensitive film and the field oxide film are CMP to define an active region and to form a device isolation film.

In this case, it is not necessary to grow the silicon film according to the SEG process thicker than the field oxide film, so that the growth time of the silicon film can be drastically reduced as compared with the conventional one, and thus the problem of conventional productivity can be solved.

In detail, FIGS. 2A to 2E are cross-sectional views of processes for describing a method of manufacturing a semiconductor device according to an embodiment of the present invention.

Referring to FIG. 2A, a field oxide film 22 is grown on a silicon substrate 21 through a field oxidation process. At this time, the thickness of the field oxide film 22 is grown to a thickness such that the cell-to-cell and junction leakage currents can be suppressed, for example, about 2000 to 5000 mA.

In addition, the field oxidation is carried out at a temperature of about 900 to 1175 ° C, and also in a dry, wet, or dry and wet mixing mode, and furthermore, contamination by metallic impurity. It can be proceeded by adding TCA or HCl to control.

Referring to FIG. 2B, in the state in which a photoresist pattern (not shown) is formed on the field oxide layer 22 according to a known photolithography process, the etching of the field oxide layer 22 using the photoresist pattern is performed. To form a trench 23 that exposes the substrate active region. Thereafter, the photoresist pattern is removed.

Referring to FIG. 2C, the substrate surface exposed by the trench 23 is subjected to H 2 baking and HF vapor to remove native oxide from the surface. At this time, the H2 baking is performed for 10 seconds or more at 700 ~ 1200 ℃, after which the HF steam treatment is performed for 25 seconds or less.

Next, the silicon film 24 is grown by the SEG process on the single crystal silicon substrate 21 exposed by the trench 23 and processed to enable epitaxial growth of silicon by H2 baking and HF steam treatment. . Here, in the SEG process, a mixed gas of DCS, HCl, H2 or Si2H4, Cl is used as the source, the temperature is about 700 to 1200 ° C, and the base pressure of the equipment is about 10E-6 to 10E-8 Torr. The process pressure is about 10E-5 Torr. In particular, the growth thickness of the silicon film 24 is set to 50-95% of the thickness of the field oxide film 22.

Referring to FIG. 2D, a photosensitive film 25 is coated on the field oxide film 22 including the silicon film 24. At this time, the photosensitive film 25 overcomes the step difference between the field oxide film 22 and the silicon film 24 and is formed to have a flat surface.

Referring to FIG. 2E, the photosensitive film 25 including the portion of the silicon film 24 and the field oxide film 22 are CMP so that the silicon film 24 is exposed, and as a result, the active silicon film 24 is formed. The device isolation region in which the region 30 and the device isolation layer 32 are formed is simultaneously defined. At this time, since the surface of the photosensitive film 25 is flat, the surface of the silicon film 24 and the element isolation film 32 that are polished and exposed are also prevented from generating a step or a mote.

Thereafter, a series of well-known subsequent processes are performed to manufacture the semiconductor device of the present invention.

According to the method of the present invention as described above, the silicon film is grown by using the SEG process, but the silicon film is not grown thicker than the field oxide film, and thus the silicon film growth time is reduced by about 10 to 30% compared with the conventional method. In this way, productivity can be improved.

Meanwhile, in the above-described embodiment of the present invention, the CMP process is performed by removing the CMP process to a part of the upper part of the silicon film. However, as another embodiment of the present invention, the CMP process for the photoresist film and the field oxide film is illustrated. As shown in Fig. 3, the target may be a target that stops at the top of the silicon film 24.

In this case, in the above-described embodiment, since the active region and the device isolation film have the same height, a loss of the device isolation film may occur in a subsequent cleaning process, and thus, a mort may be generated. In the embodiment, since the device isolation film has a higher height than the active region in relation to the termination of the CMP on the upper part of the silicon film, even if a part of the device isolation film is lost in the subsequent cleaning process, the generation of mort can be prevented. margin).

Of course, in this embodiment, since the photoresist film may remain on the silicon film, a photoresist strip process must be added later.

As described above, the present invention can fundamentally prevent the generation of mort by forming the cast type device isolation layer using the SEG process, thereby improving device characteristics and reliability.

In addition, the present invention is to grow a silicon film using the SEG process, but after the silicon film is grown lower than the upper surface of the field oxide film, the device isolation film including the active region is formed through the entire application of the photosensitive film and CMP, You can improve your productivity by reducing your growth time.                     

As mentioned above, although specific embodiments of the present invention have been described and illustrated, modifications and variations can be made by those skilled in the art. Accordingly, the following claims are to be understood as including all modifications and variations as long as they fall within the true spirit and scope of the present invention.

Claims (11)

Growing a field oxide film on the entire surface of the silicon substrate; Etching the field oxide layer to expose the active region of the silicon substrate to form a trench; Epitaxially growing a silicon film in the trench with the silicon substrate as a seed so that an upper surface thereof has a lower height than an upper surface of the field oxide film; Coating a photoresist film on the silicon film and the field oxide film; And And chemically polishing the photoresist film and the field oxide film, including an upper portion of the silicon film to expose the silicon film, thereby defining an active region and a device isolation region. The method of manufacturing a semiconductor device according to claim 1, wherein the field oxide film is grown to a thickness of 2000 to 5000 kPa. The method of claim 1 or 2, wherein the field oxidation process for forming the field oxide film is selected from the group consisting of dry, wet, and a mixed method of dry and wet at a temperature of 900 ~ 1175 ° C. Method of manufacturing a semiconductor device, characterized in that carried out in any one way. The method of claim 3, wherein the field oxidation process for forming the field oxide film is performed by adding TCA or HCl to control contamination by metallic impurity. The method of claim 1, further comprising removing the natural oxide film formed on the exposed silicon substrate surface by the trench by performing H 2 baking and HF steaming after forming the trench and before growing the silicon film. The method of manufacturing a semiconductor device, characterized in that it further comprises a step. The method of claim 5, wherein the H 2 baking is performed at 700 to 1200 ° C. for at least 10 seconds, and the HF vapor treatment is performed at 25 seconds or less. According to claim 1, wherein the growth of the silicon film according to the silicon epitaxial growth process using a mixed gas of DCS, HCl, H2 or Si2H4, Cl as a source, the temperature is 700 ~ 1200 ℃, the base pressure of the equipment A low pressure of 10E-6 to 10E-8 Torr and a process pressure of ˜10E-5 Torr. The method of manufacturing a semiconductor device according to claim 1, wherein the silicon film is grown to a thickness corresponding to 50 to 95% of the thickness of the field oxide film. Growing a field oxide film on the entire surface of the silicon substrate; Etching the field oxide layer to expose the active region of the silicon substrate to form a trench; Removing the native oxide film on the surface of the silicon substrate exposed by the trench by H2 baking and HF steam treatment; Epitaxially growing a silicon film in the trench with the silicon substrate as a seed so that an upper surface thereof has a lower height than an upper surface of the field oxide film; Coating a photoresist film on the silicon film and the field oxide film; Defining an active region and an isolation region by chemical mechanical polishing of the photoresist layer and the field oxide layer with a target of stopping at an upper portion of the silicon layer; And Removing the photoresist film remaining on the silicon film. The method of manufacturing a semiconductor device according to claim 9, wherein the field oxide film is grown to a thickness of 2000 to 5000 kPa. 10. The method of claim 9, wherein the silicon film is grown to a thickness corresponding to 50 to 95% of the thickness of the field oxide film.

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