KR100983696B1 - High integrated semiconductor device - Google Patents

Abstract

The present invention provides a method of forming an insulating film buried in a general semiconductor substrate rather than an SOI substrate in manufacturing a highly integrated semiconductor memory device including a floating body transistor. In the method of manufacturing a semiconductor device according to the present invention, a method of manufacturing a floating body region may be performed by etching a semiconductor substrate, forming an anti-oxidation film on the floating body region, and oxidizing a semiconductor substrate exposed between the floating body regions, thereby lowering the floating body region. Forming an insulating layer on the substrate.

Semiconductor, LOCOS, insulating layer, antioxidant

Description

Highly Integrated Semiconductor Device {HIGH INTEGRATED SEMICONDUCTOR DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a process for forming a unit cell including a floating body cell transistor used in a highly integrated semiconductor memory device using an SOI substrate.

In a system composed of a plurality of semiconductor devices, the semiconductor memory device is for storing data. When data is requested from a data processing device such as a central processing unit (CPU), the semiconductor memory device outputs data corresponding to an address input from a device requesting data, or at a position corresponding to the address. Stores data provided from the data requesting device.

As the data storage capacity of the semiconductor memory device increases, the size of a plurality of unit cells becomes smaller and smaller, and the size of various components for read or write operations decreases. Therefore, it is important to minimize the area occupied by each element by integrating any unnecessary wiring or transistors inside the semiconductor memory device. In addition, reducing the size of the plurality of unit cells included in the semiconductor memory device also greatly increases the degree of integration.

For example, a DRAM (Dynamic Random Access Memory), which is a volatile memory device capable of storing data in a state in which power is applied, is a unit cell of a semiconductor memory device. The unit cell is composed of one transistor and one capacitor. However, as the design rules decrease, the area of the plane that can form the capacitors decreases. In order to overcome this problem, efforts have been made to develop a material constituting the insulating film in the capacitor in order to improve the capacitance of the capacitor having a reduced area in order to stably store data. As a result, the reduction of design rules causes the normal read and write operations to become difficult to perform and the refresh characteristics become worse as the value of the junction resistance of the storage node SN and the transistor turn-on resistance increases in the unit cell. .

In the case of the unit cell including the capacitor, such as the semiconductor memory device described above, when data of "1" is stored, the charge temporarily stored in the storage node SN between the capacitor and the transistor is caused by the leakage current generated at the junction and the characteristics of the capacitor. Phenomenon such as leakage current decreases over time. For this reason, DRAM must be refreshed periodically to prevent data loss.

In order to overcome this problem, in order to be able to store a large amount of charge in the storage node (SN) in the unit cell until now to try to increase the capacitance value (Cs) of the capacitor. As a representative method for increasing the capacitance value Cs of a capacitor, a method of reducing leakage current by changing an oxide film used as an insulating film of a capacitor to a high dielectric film formed of an insulating material having a high dielectric constant such as a nitrided oxide film and a capacitor In order to increase the capacitance value (Cs) of the capacitor has been proposed to increase the surface area of the two electrodes of the capacitor by forming a capacitor having a two-dimensional planar structure as a three-dimensional cylinder structure, a trench structure.

However, as the design rule decreases, it is inevitable that the planar area for forming the capacitor is inevitably reduced, and the development of materials constituting the insulating film in the capacitor has become difficult. Accordingly, as the value of the junction resistance of the storage node SN and the turn-on resistance of the transistor increases in the unit cell, normal read and write operations become difficult to perform and the refresh characteristics become worse.

The unit cell in the improved semiconductor memory device proposed to improve this includes a transistor having a floating body. That is, the semiconductor memory device can store data in a floating body of a transistor in a unit cell without including a capacitor that has conventionally been used to store data in a unit cell. The application of floating body transistors eliminates the need for unit cells to have capacitors, which makes it possible to further reduce the size of the unit cells.

Generally, floating body transistors are formed on an SOI substrate. Here, the SOI substrate is a wafer having a structure in which an insulating film is formed between two silicon films. The gate pattern of the floating body transistor is formed on the upper silicon film formed on the buried insulating film. Source / drains formed in the upper silicon films on both sides of the gate pattern are formed to contact the buried insulating film for electrical isolation between neighboring floating body transistors. As a result, the upper silicon film under the gate pattern becomes a floating body surrounded by the gate pattern, the source / drain and the buried insulating film.

SOI substrates including buried insulating films are very useful for forming a floating body that is electrically isolated from neighboring floating body transistors to store holes in the occurrence of hot carriers. However, the method of forming the recessed source / drain in the SOI substrate increases the production cost of the semiconductor device due to the high cost of the SOI substrate.

When manufacturing a semiconductor device including a floating body transistor using a general semiconductor substrate to reduce the production cost, a separate manufacturing process is required to form an insulating layer that can play an equivalent role to the buried insulating film of the SOI substrate. Do. A method generally used in such a process is to etch a semiconductor substrate using a mask to form an insulating film and heat treatment.

However, due to the etching process using a mask on the semiconductor substrate used to reduce the production cost and the deposition of the insulating film, the time and cost required for manufacturing the semiconductor device are increased again. In addition, an etching process using a mask may generate alignment errors in the fabrication of highly integrated semiconductor devices, which may adversely affect the yield of semiconductor devices. In particular, the yield reduction of semiconductor devices directly raises the production cost of semiconductor devices. As a result, in spite of using a semiconductor substrate instead of an SOI substrate, the manufacturing method of a semiconductor device including a floating body transistor of the related art requires a further process using a separate mask for forming an insulating layer, thereby reducing production costs. Hard to expect effects. For this reason, it is difficult to manufacture a semiconductor device including a floating body transistor using a general semiconductor substrate.

In order to solve the above-mentioned problems, the present invention is to form an insulating film buried in a general semiconductor substrate, not an SOI substrate, in manufacturing a highly integrated semiconductor memory device including a floating body transistor. A method for manufacturing a semiconductor substrate including a buried insulating film and defining a floating body region using a growing Local Oxidation of Silicon (LOCOS) process is proposed.

According to an embodiment of the present invention, a method of forming a floating body region by etching a semiconductor substrate, forming an anti-oxidation layer on the floating body region, and oxidizing the semiconductor substrate exposed between the floating body regions may provide an insulating layer under the floating body region. It provides a method of manufacturing a semiconductor device comprising forming a.

Preferably, the antioxidant film is characterized in that it comprises a nitride film.

Preferably, the manufacturing method of the semiconductor device further comprises the step of embedding polysilicon on the insulating layer and planarizing to expose the floating body region.

Preferably, the step of determining the floating body region by etching the semiconductor substrate comprises: forming a mask layer on the semiconductor substrate, patterning the mask layer by an etching process using a mask defining the floating body region; Etching the semiconductor substrate using the patterned mask layer.

Preferably, the mask layer is characterized in that it comprises a nitride film.

Preferably, the step of forming an antioxidant film on the floating body region is the step of depositing the antioxidant film on the top and sidewalls of the structure including the floating body region and the mask layer and removing the antioxidant film formed between the structure Exposing the semiconductor substrate.

Preferably, the method of manufacturing the semiconductor device further includes forming a gate oxide film and a gate pattern on the floating body region.

The present invention also provides a method of exposing a portion of a silicon layer, etching the exposed portion of the silicon layer to determine an active region, forming an antioxidant layer on the active region, and exposing the silicon layer between the active regions. And forming an insulating layer under the active region by oxidizing the oxide.

Preferably, the method of forming the semiconductor substrate further comprises the step of embedding a conductive layer between the active region.

Preferably, the method of forming the semiconductor substrate further comprises the step of embedding a device isolation film between the active region.

The present invention can manufacture a semiconductor device including a floating body transistor by forming an insulating film buried in a general semiconductor substrate instead of an SOI substrate, thereby reducing production costs and improving productivity.

In addition, the present invention has an advantage in that a buried insulating film can be selectively formed only in a region where a floating body transistor is to be formed on a general semiconductor substrate in manufacturing a semiconductor device including a floating body transistor and a transistor not including a floating body.

The present invention provides a method of manufacturing a semiconductor device including a floating body transistor using a general semiconductor substrate composed of a silicon layer without an insulating layer other than an SOI substrate. In particular, the present invention is characterized in that the floating body region can be secured by performing an oxidation process on only part of the semiconductor substrate. Hereinafter, a method of manufacturing a semiconductor device including a floating body transistor according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 to 7 are cross-sectional views illustrating a method of manufacturing a semiconductor device in accordance with an embodiment of the present invention.

Referring to FIG. 1, a mask layer 20 is deposited on a semiconductor substrate 10 composed of a silicon layer. Here, the mask layer 20 may be formed of a nitride film, and as a mask material that may be used to etch the underlying etched layer, the etching selectivity of the mask layer 20 may be higher than that for etching the silicon layer more than a predetermined depth. In addition, the mask layer 20 further has a function of preventing the lower etching layer from being oxidized during the oxidation process.

Referring to FIG. 2, the semiconductor substrate 10 and the mask layer 20 are patterned through an etching process using a mask defining the floating body region 10a. In order to determine the floating body region 10a on the semiconductor substrate 10, in the present invention, after the photoresist is deposited on the mask layer 20, the exposure process is performed using a mask, the semiconductor substrate 10 and the mask layer ( 20) or when forming a fine pattern of a predetermined width or less may be performed SPT process using a spacer.

As shown in FIG. 3, an antioxidant layer 30 is formed on the structure including the floating body region 10a and the mask layer 20. At this time, the antioxidant film 30 is composed of a nitride film and serves to prevent the floating body region 10a from being oxidized in a subsequent oxidation process.

Referring to FIG. 4, the semiconductor substrate 10 is exposed by removing the anti-oxidation film 30 formed on the semiconductor substrate 10 between the floating body regions 10a through an etch-back process. At this time, the anti-oxidation film 30 formed on the sidewall of the floating body region 10a is left as it is, and the anti-oxidation film 30 formed on the mask layer 20 may be removed or remain.

Referring to FIG. 5, a LOCOS process is performed to oxidize the exposed semiconductor substrate 10. As the semiconductor substrate 10 exposed locally through the LOCOS process is oxidized, an insulating layer 40 is formed under the floating body region 10a. Specifically, the oxide film formed through the LOCOS process grows in the vertical direction and the horizontal direction around the exposed semiconductor substrate 10, and in particular, an area such as a bird's beak is formed in the horizontal direction. . In the present invention, the oxide layer grown around the exposed semiconductor substrate 10 is horizontally bonded with another neighboring oxide layer until a single insulating layer is formed below the floating body region 10a as shown. To carry out the process.

On the other hand, since the oxide film grown through the LOCOS process can penetrate into the floating body region 10a and expand, in order to determine the floating body region 10a so that the volume of the floating body region 10a is not reduced. When etching the semiconductor substrate 10 should be etched to a sufficient depth.

After the formation of the insulating layer 40, the mask layer 20 and the antioxidant layer 30 formed on the top and sidewalls of the floating body region 10a are removed as shown in FIG. 6.

Referring to FIG. 7, the conductive material is embedded between the floating body regions 10a and then planarized so that the floating body regions 10a are exposed. Here, the embedded conductive material includes polysilicon and serves as a landing plug 50 connected to the source / drain after the formation of the floating body transistor.

After forming the semiconductor substrate including the buried insulating layer 40 and the floating body region 10a and the landing plug 50 are defined, a gate oxide film and a gate electrode are formed on the floating body region 10a, although not shown. A floating body transistor is completed by forming a gate pattern including the floating pattern. In this case, the gate pattern includes at least one gate electrode, a gate hard mask insulating layer, and a spacer.

As described above, in the method of manufacturing a semiconductor device according to an embodiment of the present invention, a semiconductor substrate is etched to determine a floating body region, an oxide barrier layer is formed on the floating body region, and the semiconductor is exposed between the floating body regions. The substrate is oxidized to form an insulating layer under the floating body region. Through this process, before forming the gate pattern of the floating body transistor, in the present invention, an insulating layer embedded in a semiconductor substrate composed of a silicon layer is formed, and a floating body region and a landing plug are formed.

Furthermore, the present invention forms an insulating layer embedded in a semiconductor substrate composed of a silicon layer for manufacturing a semiconductor device including a floating body transistor. The floating body region 10a illustrated in FIG. 7 corresponds to the active region and the landing plug 50 corresponds to the inactive region, thereby forming an isolation layer instead of the landing plug 50. In addition, when the semiconductor device includes both the floating body transistor and the general transistor, the buried insulating layer may be formed only in a part of the semiconductor device. Therefore, only a part of the semiconductor substrate including the silicon layer (for example, a cell region including a floating body transistor) is exposed to form a buried insulating film, and the other regions (for example, a peripheral region) are buried. It is also possible not to form the insulating film.

A method of forming a semiconductor semiconductor substrate according to an embodiment of the present invention includes exposing a portion of a silicon layer, determining an active region by etching the exposed portion, forming an antioxidant layer on the active region, and Oxidizing the silicon layer exposed between the regions to form an insulating layer under the active region. Thereafter, a conductive layer may be buried in the insulating layer between the active regions, or a device isolation film may be buried.

As described above, in the method of manufacturing the semiconductor device according to the exemplary embodiment of the present invention, an insulating layer is formed under the floating body region through a LOCOS process after securing the floating body region before forming the gate pattern. As a result, a semiconductor device including a floating body transistor may be implemented by using a general semiconductor substrate made of a silicon layer instead of using an SOI substrate including an insulating layer buried between two silicon layers.

It will be apparent to those skilled in the art that various modifications, additions, and substitutions are possible, and that various modifications, additions and substitutions are possible, within the spirit and scope of the appended claims. As shown in Fig.

1 to 7 are cross-sectional views illustrating a method of manufacturing a semiconductor device in accordance with an embodiment of the present invention.

Claims (10)

Etching the semiconductor substrate to determine a floating body region in a portion where the semiconductor substrate is not etched; Forming an anti-oxidation film on the floating body region; And Oxidizing the semiconductor substrate exposed between the floating body regions to form an insulating layer under the floating body region. Method for manufacturing a semiconductor device comprising a. The method of claim 1, The antioxidant film is a manufacturing method of a semiconductor device, characterized in that it comprises a nitride film. The method of claim 1, Embedding polysilicon over the insulating layer and planarizing the floating body region to expose the floating body region. The method of claim 1, Determining the floating body region by etching the semiconductor substrate Forming a mask layer on the semiconductor substrate; Patterning the mask layer by an etching process using a mask defining the floating body region; And And etching the semiconductor substrate by using the patterned mask layer. The method of claim 4, wherein And the mask layer comprises a nitride film. The method of claim 4, wherein Forming an anti-oxidation film on the floating body region Depositing the anti-oxidation layer on the top and sidewalls of the structure including the floating body region and the mask layer; And Removing the antioxidant film formed between the structures to expose the semiconductor substrate. The method of claim 1, After forming the insulating layer, And forming a gate oxide layer and a gate pattern on the floating body region. Exposing a portion of the silicon layer; Etching the exposed portion to determine an active region in a portion where the silicon layer is not etched; Forming an anti-oxidation film in the active region; And Oxidizing the silicon layer exposed between the active regions to form an insulating layer under the active region Method of forming a semiconductor substrate comprising a. The method of claim 8, After forming the insulating layer, And embedding a conductive layer between the active regions. The method of claim 8, After forming the insulating layer, Forming a device isolation layer between the active regions;

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