KR100876880B1 - Cylindrical Capacitor Formation Method - Google Patents

Abstract

The present invention discloses a method of forming a structurally stable cylindrical capacitor. The disclosed method comprises the steps of providing a semiconductor substrate having a storage node contact formed thereon, depositing an etch barrier film and a first plate node material film on the substrate in turn, the first plate node material film and an etch barrier Etching a film in sequence to form a trench that exposes the first plate node and the storage node contact; forming a first dielectric film on the sidewalls of the trench; and forming a storage node on the trench surface including the first dielectric film. Forming a second dielectric layer on the storage node, the first dielectric layer, and the first plate node; and forming a second plate node in the form of a trench on the second dielectric layer. And electrically connecting the second plate node and the first plate node. According to the present invention, the dip-out process can be omitted by forming the storage node after the plate node is formed, thus preventing the storage node from falling down in the dip-out process. .

Description

Method for forming cylindric capacitor

1A to 1E are cross-sectional views of processes for explaining a method of forming a cylindrical capacitor according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1 semiconductor substrate 2 interlayer insulating film

3: storage node contact 4: etching barrier

5: first plate node material film 5a: first plate node

6: first dielectric layer 7: storage node

8: second dielectric film 9: second plate node

10a, 10b: Capacitor 11: Insulation film

T: Trench C: Contact Hole

The present invention relates to a method of forming a capacitor of a semiconductor device, and more particularly, to a method of forming a cylindrical capacitor capable of preventing the storage node from falling down.                         

As the demand for semiconductor memory devices has soared, various techniques for obtaining high capacity capacitors have been proposed. Here, the capacitor is a structure in which a dielectric film is interposed between the storage node and the plate node, the capacitance of which is proportional to the surface area of the electrode and the dielectric constant of the dielectric film, and the distance between the electrodes, that is, It is inversely proportional to the thickness of the dielectric film.

Therefore, in order to obtain a high capacity capacitor, it is required to use a dielectric film having a large dielectric constant, to enlarge the electrode surface area, or to reduce the distance between the electrodes. However, reducing the distance between the electrodes, that is, the thickness of the dielectric film has its limitation, and researches for forming a capacitor having a high capacity have been conducted by using a dielectric film having a high dielectric constant or increasing the electrode surface area.

As an example of increasing the electrode surface area, a storage node may be formed in a concave shape and a cylindrical shape, and in recent years, a cylindrical shape is more preferred than a concave shape.

This is because a cylindrical shape using an electrode area as an internal area as well as an external area may have a lower capacitor height than a concave type using only an internal area. That is, it is advantageous to increase the electrode height in order to obtain a high capacity, but in this case, it may be somewhat difficult to proceed with the subsequent process due to the step.

On the other hand, although not shown and described, in order to form a cylindrical capacitor, a wet etching process called a dip-out process for removing an oxide film used as a form for forming a cylindrical storage node must be performed. .

However, this process is a problem of structural instability due to high integration. That is, in various subsequent cleaning processes including the deep-out process, collapse of the storage node may occur due to high integration, which increases the capacitor's bottom CD (critical dimension) area while increasing the height of the capacitor. This is also due to the reduction in the spacing between the capacitors.

As a result, in the formation of the cylindrical capacitor, as the device is highly integrated, the collapse of the storage node will become more severe. Accordingly, the manufacturing yield and reliability of the device are deteriorated due to the bridge problem between neighboring storage nodes. It must be.

Accordingly, an object of the present invention is to provide a method of forming a cylindrical capacitor capable of preventing the collapse of the storage node due to high integration, which is devised to solve the above problems.

Another object of the present invention is to provide a method of forming a structurally stable cylindrical capacitor.

In order to achieve the above object, the present invention provides a method comprising: providing a semiconductor substrate on which a storage node contact is formed; Sequentially depositing an etch barrier film and a first plate node material film on the substrate; Etching the first plate node material layer and the etching barrier layer in order to form a trench exposing the first plate node and the storage node contact; Forming a first dielectric film on sidewalls of the trench; Forming a storage node on the trench surface including the first dielectric layer; Depositing a second dielectric film on the storage node, the first dielectric film, and the first plate node; Forming a second plate node in the form of filling the trench on the second dielectric layer; And electrically connecting the second plate node and the first plate node.

Here, the first dielectric film is made of a material having a relatively high dielectric constant, and the second dielectric film is made of a material having relatively excellent step coverage. Further, the first dielectric film and the second dielectric film are the same material but are deposited in different thicknesses.

Forming a first dielectric film on the trench sidewalls includes depositing a first dielectric film on the trench surface and a first plate node, and etching back the first dielectric film onto a first plate node and a trench bottom surface. And removing the portion of the first dielectric film.

According to the present invention, the dip-out process can be omitted by forming the storage node after the plate node is formed, thus preventing the storage node from falling down in the dip-out process.

(Example)

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

1A to 1E are cross-sectional views of processes for describing a method of forming a cylindrical capacitor according to an embodiment of the present invention.

Referring to FIG. 1A, an interlayer insulating film 2 is formed to cover a predetermined underlayer, and a semiconductor substrate 31 having a storage node contact 3 formed therein is provided in the interlayer insulating film 2. Thereafter, an etch barrier film 4 is deposited on the interlayer insulating film 2 including the storage node contacts 3, and then a first plate node material film 5 is deposited on the etch barrier film 4. .

The etching barrier layer 4 is formed to prevent the recess of the storage node contact 3 from occurring in the subsequent etching process of the first plate node material layer 5. The first plate node material film 5 is preferably deposited to a thickness corresponding to the desired capacitor height.

Referring to FIG. 1B, the first plate node material film 5 is first etched using an etch selectivity between the first plate node material film 4 and the etch barrier film 5, and then secondly. The etching barrier layer 4 is etched to form the first plate node 5a and to expose the storage node contact 3 to form the trench T defining the capacitor formation region.

Next, after depositing the first dielectric film 6 on the trench T surface and the first plate node 5a, an etch back process is performed on the first dielectric film 6 without using a mask. The portion deposited on the bottom surface of the trench T and the portion deposited on the first plate node 5a are removed. In this case, when the first dielectric film 6 remains on the first plate node 5a in the form of a spacer, it may be a breakdown source between the plate node and the storage node in the manufactured capacitor. It is desirable to prevent such defects from occurring.

Referring to FIG. 1C, a storage node material film is deposited on the substrate resultant. Then, after applying a photoresist film (not shown) on the storage node material film to fill the trench (T), and the chemical mechanical polishing (CMP) of the photoresist film and the storage node material film to expose the first plate node (5a) Then, the remaining photoresist film is removed to form the storage node 7 on the trench T surface including the first dielectric film 6.

In this case, the CMP may be performed by setting a target to completely remove the first dielectric film, which may have remained on the first plate node 5a in the previous process step.

Referring to FIG. 1D, after depositing a second dielectric film 8 on the substrate resultant, a second plate node material film is deposited to a thickness that completely fills the trench T, and then patterned to form a second plate node. (9) is formed, and through this, capacitors 10a and 10b are formed. At this time, the first plate node 5a and the second plate node 9 are electrically shorted by the second dielectric film 8.

Referring to FIG. 1E, after the insulating film 11 is deposited on the substrate resultant up to the step for electrical insulation with the metal wiring, the insulating film 11 and the second plate node material film 9 are manufactured according to a known process. ), The second dielectric film 8 and the first plate node material film 5 are etched to form a contact hole C for metal wiring.                     

Thereafter, although not shown, the first plate node material film 5 and the second plate node material film 9, which are short-circuited through a metal wiring process, are electrically connected to complete the formation of the cylindrical capacitor according to the present invention. Then, they go through a series of subsequent processes.

According to the method of the present invention as described above, the tip-out process is not necessary because the capacitor is formed in such a manner that the plate node, which is the outer area node, is formed first, and then the storage node, which is the inner area node, is not required. The collapse of the storage node is essentially prevented.

In addition, since the method of the present invention forms the plate node after forming the plate node as described above, it is prevented by the bridge between the capacitors in connection with the fact that foreign matter cannot be interposed between the capacitors.

Meanwhile, in the method of the present invention, a material having a higher dielectric constant than that of the second dielectric film is used as the first dielectric film, and step coverage is relatively relatively compared to the first dielectric film as the second dielectric film. By using a material having good coverage, it is possible to increase the capacitor capacity and to improve the breakdown characteristics between the plate node and the storage node.

In addition, the first dielectric film and the second dielectric film may be made of the same material, but the above effects may be obtained by varying the deposition thickness.

As described above, the present invention can fundamentally solve the collapse of the storage node because the capacitor is formed by a step of omitting the dip-out process.

Therefore, the present invention can secure the reliability and manufacturing yield of the capacitor, thereby securing the device characteristics and reliability.

In addition, the present invention can provide a capacitor having high capacity and excellent reliability by varying the type and deposition thickness of the first dielectric film and the second dielectric film.

Meanwhile, 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 (4)

Providing a semiconductor substrate on which storage node contacts are formed; Sequentially depositing an etch barrier film and a first plate node material film on the substrate; Etching the first plate node material layer and the etching barrier layer in order to form a trench exposing the first plate node and the storage node contact; Forming a first dielectric film on sidewalls of the trench; Forming a storage node on the trench surface including the first dielectric layer; Depositing a second dielectric film on the storage node, the first dielectric film, and the first plate node; Forming a second plate node in the form of filling the trench on the second dielectric layer; And And electrically connecting the second plate node and the first plate node. The method of claim 1, wherein the first dielectric film is made of a material having a relatively high dielectric constant, and the second dielectric film is made of a material having a relatively good step coverage. The method of claim 1, wherein the first dielectric film and the second dielectric film are formed of a same material but have different thicknesses. The method of claim 1, wherein the forming of the first dielectric layer on the trench sidewalls comprises: Depositing a first dielectric film on the trench surface and the first plate node, and etching back the first dielectric film to remove a portion of the first dielectric film deposited on the first plate node and the bottom of the trench. Cylindrical capacitor forming method, characterized in that.

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