KR20080097030A - Reservoir capacitor and forming method of the same - Google Patents

Abstract

A reservoir capacitor and a forming method of the same are provided to steadily form the photosensitive pattern for forming the recess region by forming the material of the oxide film based of the line type at the recess region. The semiconductor substrate comprises the first groove(H1) of the multiple having the first depth in the recess formation area serving as the first electrode and having the peripheral area including the recess formation area of the line type; the second groove(H2) of the multiple having the second depth according to the direction weaving by hands with the recess formation area. The storage capacitor included(240) comprises the gate insulating layer(241) serving as the dielectric layer formed on semiconductor substrate including the first groove and the second groove; the gate conductive layer(242) serving as the second electrode which is formed in order to reclaim the groove on the gate insulating layer.

Description

Storage capacitor and forming method of the same

1 is a cross-sectional view illustrating a capacitor in a conventional peripheral region.

2 is a cross-sectional view showing a storage capacitor in a peripheral region according to an embodiment of the present invention.

3A to 3F are cross-sectional views illustrating processes for manufacturing a storage capacitor in a peripheral region according to an exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

200,300: semiconductor substrate 210,310: pad oxide film

220,320: pad nitride film 240,340: storage capacitor

241,341: gate insulating film 242,342: gate conductive film

M1: first photoresist pattern M2: second photoresist pattern

H1: first groove H2: second groove

The present invention relates to a storage capacitor and a method for forming the same, and more particularly, to a storage capacitor having a stable and high capacity in a small area and a method for forming the same.

In recent years, as the productivity of DRAM (DRAM) and the technology (Tech) have evolved, as the design rules of semiconductor devices have become smaller, the circuit configuration method in the peripheral area has become increasingly important.

In general, in the circuits in the peripheral region, a pumping capacitor is required for charge pumping, and a voltage level of a power line is prevented by preventing noise caused by switching. Many capacitors, such as storage capacitors, are needed for stabilization purposes.

1 is a cross-sectional view illustrating a capacitor in a conventional peripheral region.

As shown in the drawing, a large-sized transistor (Tr) is fabricated in a peripheral area, and a gate oxide of the transistor, that is, a planar gate oxide, is used as a capacitor. The pumping capacitor or the storage capacitor is constituted.

The area occupied by the pumping capacitor or the storage capacitor in the peripheral area occupies most of the portion except the circuit of the peripheral area, which corresponds to a large area corresponding to about 30% of the peripheral area.

In FIG. 1, reference numeral G denotes a gate, BLC denotes a bit line contact, BL denotes a bit line, M1C denotes a first contact plug, and M1 denotes a first metal wiring.

On the other hand, as the design rule of the device is gradually smaller, correspondingly, the peripheral area is also smaller, and due to the capacitor occupying a large area, many losses are inevitable in terms of area of the peripheral area.

In other words, a large number of capacitors are required in the peripheral area. As the capacitor occupies a large part of the total area of the peripheral area, this is a situation that is a big obstacle in terms of area, and the pressure level is decreasing. Considering this becomes a bigger problem in the future.

Therefore, a method of increasing the effective area of the gate oxide film has been proposed by applying a recess gate process applied when forming a cell transistor.

Since the storage capacitor applying the recess gate process can secure high capacitor capacity even if the area of the peripheral circuit is reduced due to the high integration of the semiconductor device, the voltage level of the power line is stabilized in the peripheral area as well as the size of the semiconductor device. This can reduce DRAM manufacturing costs.

However, due to the miniaturization of the pattern, when the recess gate process is applied in an active area of a large area such as a storage capacitor, a fine photoresist pattern may collapse, and the photoresist pattern may not be properly formed in the cell transistor and the horizontal direction. Are happening.

An object of the present invention is to provide a storage capacitor and a method of forming the same, which can prevent a phenomenon in which a fine photoresist pattern falls when forming a storage capacitor to which a recess gate process is applied.

Another object of the present invention is to provide a storage capacitor and a method of forming the same, which can form a storage capacitor having a high capacity in a narrow area.

In order to achieve the above object, the present invention provides a plurality of first grooves having a peripheral region including a line type recess formation region and having a first depth in the recess formation region serving as a first electrode. And a plurality of second grooves having a second depth along a direction perpendicular to the recess formation region; A gate insulating film serving as a dielectric film formed on the semiconductor substrate including the first and second grooves; And a gate conductive film serving as a second electrode formed to fill a groove on the gate insulating film.

The present invention also provides a method, comprising: forming a pad oxide film and a pad nitride film on a semiconductor substrate having a peripheral region including a line type recess formation region and serving as a first electrode; Forming a first photoresist pattern on the pad nitride film, the first photosensitive film pattern exposing the pad nitride film in a line type, spaced apart from each other along a direction perpendicular to the recess formation region; Etching the exposed pad nitride layer to expose the pad oxide layer; Removing the first photoresist pattern; Oxidizing the exposed pad oxide film; Removing the pad nitride film; Forming a second photoresist layer pattern exposing a recess formation region on the semiconductor substrate including the oxidized pad oxide layer; Etching the exposed pad oxide layer and the semiconductor substrate to form a first groove; Removing the second photoresist pattern; Forming a second groove by removing the pad oxide film formed along a direction perpendicular to the first groove; And forming a gate insulating film serving as a dielectric film on the peripheral region of the semiconductor substrate including the first and second grooves, and a gate conductive film serving as a second electrode on the gate insulating film so that the grooves are filled. It provides a method of forming a storage capacitor comprising.

Here, the oxidation treatment of the gate insulating film may be performed by a thermal oxidation process.

(Example)

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

First, the technical principle of the present invention relates to a storage capacitor to which a recess gate processor is applied, and includes a first groove having a first depth and a second depth in a direction perpendicular to the first groove. It is provided with two grooves, through which, the storage capacitor is formed on the semiconductor substrate having the grooves of the matrix shape serving as the first electrode.

As such, since the grooves of the matrix shape of the first and second grooves are provided in the semiconductor substrate, the effective area of the gate insulating layer may be increased in a narrow area of the peripheral area according to the high integration of the semiconductor device, thereby providing a storage capacitor having a high capacity. It can be secured.

FIG. 2 is a plan view illustrating a storage capacitor according to an exemplary embodiment of the present invention. As shown in the drawing, the storage capacitor may be formed under a recess formation region in a storage capacitor formation region of a semiconductor substrate 200 serving as a first electrode. A first groove H1 having a first depth of a line type is formed, and a second groove H2 having a second depth is formed in a direction perpendicular to the first groove H1, thereby storing Matrix-shaped grooves are formed in the semiconductor substrate of the capacitor formation region, and a gate insulating film 241 serving as a dielectric film is formed on the surface of the matrix-shaped groove, and the gates are formed so that the grooves in which the gate insulating film 241 is formed are buried. And a gate conductive film 242 serving as a second electrode on the insulating film.

Here, the gate insulating film 241 is formed of an oxide film, which is interposed between the semiconductor substrate 200 serving as the first electrode and the gate conductive film 242 serving as the second electrode. As a result, the storage capacitor 240 serves as a peripheral region.

In addition, the gate insulating film 241 is formed on the surface of the matrix-shaped groove formed by the first groove H1 and the second groove 2, thereby increasing the effective area of the gate insulating film, thereby increasing the capacity of the storage capacitor. You can.

In detail, a method of forming a storage capacitor using a recess gate process according to an exemplary embodiment of the present invention will be described with reference to FIGS. 3A to 3G.

Referring to FIG. 3A, a pad oxide layer 310 and a pad nitride layer 320 are formed on a semiconductor substrate 300 having a peripheral region including a storage capacitor formation region including a line type recess formation region and serving as a first electrode. To form.

Next, a first photoresist layer pattern M1 is formed on the pad nitride layer 320 to expose the pad nitride layer 320 in a line type to be spaced apart from each other in a direction perpendicular to the recess formation region.

Referring to FIG. 3B, the exposed pad nitride layer is etched using the first photoresist layer pattern M1 as an etching mask to expose the pad oxide layer 310.

In this case, the exposed pad oxide layer 310 may have a shape that is spaced apart from each other in a direction perpendicular to the recess formation region.

Then, the first photoresist pattern is removed according to a known process.

Referring to FIG. 3C, the pad oxide layer 310 exposed by the pad nitride layer 320 is oxidized by a thermal oxidation process to form a thick portion of the exposed pad oxide layer 311 along the direction perpendicular to the recess formation region. do.

Referring to FIG. 3D, the pad nitride film is removed.

Next, a second photoresist pattern M2 is formed on the semiconductor substrate including the oxidized pad oxide film 311 to expose the recess formation region.

Here, since the pad oxide film 311, which is an oxide-based material, is formed, the fall of the second photoresist pattern M2 may be suppressed when the second photoresist pattern is formed.

Specifically, the formation of the photoresist pattern for the conventional recess gate formation region is not only difficult to form as the photoresist pattern is formed on the semiconductor substrate without the oxide-based material, and the photoresist pattern collapses due to the fine photoresist pattern. .

Accordingly, in the present invention, the pad oxide film 311, which is an oxide film-based material, is formed along the direction perpendicular to the recess gate formation region, thereby preventing the second photoresist pattern M2 from falling down.

Referring to FIG. 3E, the pad oxide layer including the exposed pad oxide layer is removed using the second photoresist layer pattern M2 as an etching mask, and the semiconductor substrate is etched to form a line type first groove H1.

Then, the second photoresist pattern is removed according to a known process.

Referring to FIG. 3F, a pad oxide film formed along a direction perpendicular to the first groove H1 is removed to form a second groove H2 having a second depth.

Here, the effective area of the subsequent gate insulating film may be increased due to the formation of the first groove H1 and the second groove H2 in the storage capacitor formation region, thereby securing a high capacitance capacitor. do.

Referring to FIG. 3G, the matrix insulating grooves including the first grooves H1 and the second grooves H2 serve as dielectric layers on the peripheral region of the semiconductor substrate and the grooves H1 and H2. ) Is formed on the gate insulating film 341 so that the gate conductive film 342 serving as the second electrode is formed, thereby forming the storage capacitor 340 according to the embodiment of the present invention.

In addition, since the process of forming the storage capacitor having the three-dimensional structure in the peripheral region according to the present invention is similar to the process of forming the semiconductor device having the recess gate structure of the cell region and the process of forming the isolation layer, There is no need for a new process for forming a storage capacitor having a structure, so there is no process burden.

As mentioned above, although the present invention has been illustrated and described with reference to specific embodiments, the present invention is not limited thereto, and the following claims are not limited to the scope of the present invention without departing from the spirit and scope of the present invention. It can be easily understood by those skilled in the art that can be modified and modified.

As described above, the present invention is provided by the line-type groove formed in the direction of the recess region and the groove formed along the direction perpendicular to the groove in the semiconductor substrate of the peripheral region including the storage capacitor region, thereby, The effective area of the gate insulating film may be increased to increase the capacity of the storage capacitor.

In addition, according to the present invention, since a line-type oxide-based material is formed in the recess region, the photoresist pattern for forming the recess region may be stably formed, and the collapse of the photoresist pattern may be prevented. have.

Claims (3)

A plurality of first grooves having a first depth in the recess formation region serving as a first electrode and a direction perpendicular to the recess formation region, the peripheral region including a line type recess formation region; A semiconductor substrate having a plurality of second grooves having two depths; A gate insulating film serving as a dielectric film formed on the semiconductor substrate including the first and second grooves; And A gate conductive film serving as a second electrode formed to fill a groove on the gate insulating film; Storage capacitor comprising a. Forming a pad oxide film and a pad nitride film on a semiconductor substrate having a peripheral region including a line type recess formation region and serving as a first electrode; Forming a first photoresist pattern on the pad nitride film, the first photosensitive film pattern exposing the pad nitride film in a line type, spaced apart from each other along a direction perpendicular to the recess formation region; Etching the exposed pad nitride layer to expose the pad oxide layer; Removing the first photoresist pattern; Oxidizing the exposed pad oxide film; Removing the pad nitride film; Forming a second photoresist layer pattern exposing a recess formation region on the semiconductor substrate including the oxidized pad oxide layer; Etching the exposed pad oxide layer and the semiconductor substrate to form a first groove; Removing the second photoresist pattern; Forming a second groove by removing the pad oxide film formed along a direction perpendicular to the first groove; And Forming a gate insulating film serving as a dielectric film on a peripheral region of the semiconductor substrate including the first and second grooves, and a gate conductive film serving as a second electrode on the gate insulating film so that the grooves are buried; Storage capacitor forming method comprising a. The method of claim 1, And oxidizing the gate insulating film by a thermal oxidation process.

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