KR100595858B1 - Semiconductor device manufacturing method - Google Patents

Abstract

The present invention relates to a method of manufacturing a semiconductor device capable of completely removing dangling bonds generated on a semiconductor substrate in a trench after trench formation.

A semiconductor device manufacturing method according to the present invention comprises the steps of forming a pattern of a sacrificial film for exposing a field region on a semiconductor substrate; Forming a trench by etching the field region of the semiconductor substrate by a predetermined depth using the pattern of the sacrificial layer as an etching mask; Forming a thermal oxide film on the entire surface of the semiconductor substrate in the trench; And performing an ion implantation process on the entire surface of the substrate including the thermal oxide film.

Dangling Bond, STI

Description

Fabrication method of semiconductor device             

1A to 1C are cross-sectional views illustrating a shallow trench isolation process according to the prior art.

2 is a cross-sectional view showing a problem according to the prior art.

3A to 3E are cross-sectional views illustrating a method of manufacturing a semiconductor device in accordance with the present invention.

Description of the main parts of the drawing

301 semiconductor substrate 302 sacrificial oxide film

303: sacrificial nitride film 304: trench

305: thermal oxide film

The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for manufacturing a semiconductor device capable of completely removing dangling bonds generated on a semiconductor substrate in a trench after trench formation.

In general, LOCOS (Local Oxidation of Silicon) technology using a nitride film has been used as an isolation technology of a semiconductor device. New isolation technologies have been actively developed to compensate for the shortcomings of the LOCOS technology. Among them, poly buffer LOCOS (PBL) and recessed LOCOS (R-LOCOS) have been widely used. These techniques are complicated to process and can not fundamentally reduce the erosion of the channel region (Bird`s Beak) by the device isolation film, there is a limit to the high integration of the semiconductor device, and the step difference with the device forming part is severely generated, which will be It is necessary to planarize.

In recent years, shallow trench isolation (STI) processes have been introduced that improve upon the problems of existing isolation technologies. The shallow trench isolation process is well suited for high integration of semiconductor devices because of its superior device isolation and small footprint compared to conventional isolation technologies.

The shallow trench isolation process forms a trench in the field region of the semiconductor substrate, gap fills an insulating film such as an oxide film in the trench by a gap filling process, and then deposits the oxide film in a chemical mechanical polishing (CMP) process. The polishing is performed to planarize the oxide film and the semiconductor substrate in the trench. As a result, the device isolation film is formed in the field region of the semiconductor substrate.

Oxides for gap-filling trenches include O ₃ -TEOS (Tetra-Ethyl-Ortho-Silicate) Atmospheric Pressure Chemical Vapor Deposition (APCVD) oxide films with high gap filling and planarization characteristics, and high density plasma chemical vapor deposition ( High Density Plasma Chemical Vapor Deposition (HDP CVD) oxide film is mainly used.

Conventional shallow trench isolation processes are performed as shown in FIGS. 1A-1C. First, as shown in FIG. 1A, an oxide film 102 is formed as a sacrificial film on a semiconductor substrate 101 such as a single crystal silicon substrate, and a nitride film 103 is laminated thereon as a hard mask layer. Then, an opening having a predetermined width is formed in a portion of the nitride film 103 and the oxide film 102 corresponding to the field region of the semiconductor substrate 101 by using a photolithography process. Next, the trench 104 is formed in the field region of the semiconductor substrate 101 by etching the semiconductor substrate 101 to a depth for the trench 104 by using the nitride film 103 as an etching mask layer.

Then, as illustrated in FIG. 1B, a thermal oxide film 105 is grown on an etching surface of the exposed semiconductor substrate 101 in the trench 104 by using a thermal oxidation process, and then a device in the trench 104 is formed. The insulating layer 106 is thickly stacked in the trench 104 and on the nitride layer 103 to sufficiently fill the trench 104 to form the separator 106. At this time, the reason for forming the thermal oxide film 105 is to heal the surface of the semiconductor substrate 101 in the trench 104 damaged in the process of forming the trench 104 by etching the semiconductor substrate 101. .

Then, as shown in FIG. 1C, the insulating film 106 is flattened on the nitride film 103 by the chemical mechanical polishing process, leaving the insulating film 106 only in the trench 104, and then the high temperature heat treatment process. The insulating film 106 in the trench 104 is densified. Thereafter, when the nitride film 103 and the oxide film 102 are etched and removed using a hydrofluoric acid solution or the like, the normal shallow trench 104 isolation process is completed.

In a conventional shallow trench isolation process, a trench formation process in which a predetermined region of a semiconductor substrate is etched to a predetermined depth is typically performed using a dry etching method such as reactive ion etching (RIE) during etching. do. Reactive ion etching is widely used as an etching method using a plasma, and thus is widely used. However, the disadvantage of damaging the surface of a semiconductor substrate in the present invention, namely, an etching target, is generated by using plasma.

In general, when using a single crystal silicon substrate that is used as a material of a semiconductor substrate, when forming a trench using reactive ion etching, as shown in FIG. 2, damage to the surface of the single crystal silicon substrate 101 inside the trench 104 may be caused by plasma damage. Dangling bond 201 is generated. The dangling bond 201 causes leakage current and adversely affects semiconductor device characteristics.

In order to solve such a problem, the conventional semiconductor device manufacturing method performs a thermal oxide film process as shown in FIG. 2 after the trench is formed by reactive ion etching, thereby performing a thermal oxide film on the single crystal silicon substrate 101 in the trench 104. A 105 was formed to seal the dangling bond to prevent leakage current due to the dangling bond.

However, since the thermal oxide film 105 is usually formed with a very fine thickness of 100 to 300 microns, there is a problem in that the dangling bonds in the trench cannot be completely sealed.

An object of the present invention is to provide a method for manufacturing a semiconductor device capable of completely removing dangling bonds generated on a semiconductor substrate in a trench after trench formation.

A semiconductor device manufacturing method of the present invention for achieving the above object comprises the steps of forming a pattern of a sacrificial film for exposing a field region on a semiconductor substrate; Forming a trench by etching the field region of the semiconductor substrate by a predetermined depth using the pattern of the sacrificial layer as an etching mask; Forming a thermal oxide film on the entire surface of the semiconductor substrate in the trench; And performing an ion implantation process on the entire surface of the substrate including the thermal oxide film.

Preferably, the ion implantation process may implant hydrogen ions.

Preferably, the ion implantation process may inject a mixture of hydrogen ions and nitrogen ions.

Preferably, after the ion implantation process, the method may further include heat treating the semiconductor substrate.

Preferably, the heat treatment temperature of the semiconductor substrate is 200 to 600 ℃.

According to a feature of the present invention, a thermal oxide film is formed inside the trench and the hydrogen ions are implanted on the thermal oxide film on the semiconductor substrate surface in the trench to cure damage to the surface of the semiconductor substrate in the trench after the formation of the trench. Existing dangling bonds can be completely removed, preventing leakage currents caused by dangling bonds.

Hereinafter, a method of manufacturing a semiconductor device according to the present invention will be described in detail with reference to the accompanying drawings. 3A to 3E are cross-sectional views illustrating a method of manufacturing a semiconductor device in accordance with the present invention.

First, as shown in FIG. 3A, an oxide film 302 is grown to a thickness of 40 to 150 으로서 as a sacrificial film on a semiconductor substrate 301 such as a single crystal silicon substrate 301 by a high temperature thermal oxidation process. Subsequently, the nitride film 303 is laminated on the oxide film 302 in a thickness of 600-1500 kPa as a hard mask layer by a low pressure chemical vapor deposition process. The oxide film 302 is to relieve stress of the semiconductor substrate 301 and the nitride film 303. The nitride film 303 is used as an etch mask layer in the formation of the trench 304 and also serves as an etch stop film in a subsequent chemical mechanical polishing process.

Then, a pattern of the photoresist film is formed on the active region of the substrate 301 so that the opening of the photoresist film (not shown) is located in the field region of the substrate 301, and the pattern of the photoresist film is used as an etching mask. The field region of the substrate 301 is exposed by completely etching the sacrificial nitride film 303 and the sacrificial oxide film 302 in the opening by a dry etching process having anisotropic etching characteristics, for example, a reactive ion etching process. Thereafter, the pattern of the photosensitive film is removed.

Subsequently, the remaining sacrificial nitride film 303 is used as an etch mask layer to etch the substrate 301 in the exposed field region to a shallow depth of about 3000 [mu] s by a reactive ion etching process. As a result, the trench 304 is formed in the field region of the substrate 301.

Referring to FIG. 3B, after formation of the trench 304 is completed, an insulating film, for example, a thermal oxide film 305 is formed on the surface of the semiconductor substrate 301 in the trench 304 by a thermal oxidation film process. Grow to the thickness of. Here, the thermal oxide film 305 is to heal the surface of the semiconductor substrate 301 in the trench 304 damaged by the plasma after the trench 304 is formed, and the atoms on the surface of the semiconductor substrate 301 in the trench 304 are precisely defined. This is to remove dangling bonds in the array. On the other hand, the thermal oxide film 305 also plays a role of improving the bonding characteristics with the device isolation film 306 to be formed in the future.

Referring to FIG. 3C, hydrogen ions are implanted into the thermal oxide film 305 by performing a hydrogen ion implantation process on the entire surface of the substrate 301 in a state where the thermal oxide film 305 is formed as described above.

In the hydrogen ion implantation process, nitrogen ions may be added together with the hydrogen ions to be implanted into the thermal oxide film 305.

When the hydrogen ion implantation process is completed, a predetermined heat treatment process is applied to the substrate 301. At this time, as for the temperature of the said heat processing process, about 200-600 degreeC is preferable. Hydrogen ions implanted into the thermal oxide film 305 in the trench 304 by the heat treatment process are activated and diffused toward the surface of the semiconductor substrate 301 in the trench 304 to diffuse into the semiconductor substrate 301 in the trench 304. It is bonded to the dangling bond present on the surface to stabilize the material properties of the surface of the substrate 301.

That is, as illustrated in FIG. 3D, the dangling bonds on the surface of the semiconductor substrate 301 in the trench 304 are combined with and removed with oxygen ions in the thermal oxide film 305 by the formation of the thermal oxide film 305. The dangling bond remaining without bonding with the oxygen ions in the thermal oxide film 305 is combined with the hydrogen ions implanted by a subsequent hydrogen ion implantation process to surface the semiconductor substrate 301 in the trench 304. Dangling bonds present in the phase are completely removed.

Referring to FIG. 3E, an insulating film 306 for an isolation layer is thickly stacked on the entire surface of the substrate 301 on the trench 304 and the sacrificial nitride film 303 outside thereof to sufficiently fill the trench 304. In this case, it is preferable that no void, that is, void, exist in the insulating film 306 for device isolation film in the trench 304. Here, the insulating layer 106 for the device isolation layer 106 may be somewhat different according to a design rule of a semiconductor device, but O ₃ -TEOS (Tetra-Ethyl-Ortho-Silicate) atmospheric pressure chemical vapor deposition (Atmosphere Pressure) It may be deposited by Chemical Vapor Deposition (APCVD) process or High Density Plasma Chemical Vapor Deposition (HDP CVD) process.

In the meantime, for convenience of description, the insulating film 306 for the device isolation film is described as a single layer, but the insulating film 306 for the device isolation film is, for example, a double layer including the oxide film 302 and the nitride film 303. It is also possible to consist of multiple layers mentioned above.

Subsequently, the insulating film 306 for the device isolation film is polished by a chemical mechanical polishing process to planarize the sacrificial nitride film 303 to finally form the device isolation film 306 in the trench 304 to manufacture the semiconductor device according to the present invention. The process is complete.

The semiconductor device manufacturing method according to the present invention has the following effects.

In order to cure damage to the surface of the semiconductor substrate in the trench by the plasma after the trench is formed, a thermal oxide film is formed inside the trench and hydrogen ions are implanted in the thermal oxide film, thereby perfecting the dangling bond present on the semiconductor substrate surface in the trench. It can be removed to prevent leakage current caused by dangling bonds.

Claims (5)

Forming a pattern of a sacrificial film for exposing the field region on the semiconductor substrate; Forming a trench by etching the field region of the semiconductor substrate by a predetermined depth using the pattern of the sacrificial layer as an etching mask; Forming a thermal oxide film on the entire surface of the semiconductor substrate in the trench; And performing ion implantation of hydrogen ions and nitrogen ions on the entire surface of the substrate including the thermal oxide film. delete delete The method of claim 1, further comprising heat treating the semiconductor substrate after performing the ion implantation process. The method of claim 4, wherein the heat treatment temperature of the semiconductor substrate is 200 to 600 ° C. 6.

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