KR100504949B1 - Method of forming a storage node of capacitor - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a storage electrode of a capacitor, wherein the primary storage is performed on a contact plug in order to improve adhesion characteristics of the storage electrode and the contact plug in the process of depositing a metal material for the storage electrode after forming the contact plug. After forming the electrode, the contact plug and the storage electrode are bonded by overetching the contact plug by an etch back process to form an inclined etching surface on the contact plug to form a secondary storage electrode with an increased surface area. Disclosed is a method of forming a storage electrode of a capacitor capable of improving the resistance to prevent the occurrence of defects and improving the electrical characteristics of the device.

Description

Method of forming a storage node of capacitor

The present invention relates to a method of forming a storage electrode of a capacitor, and more particularly, to a method of forming a storage electrode of a capacitor which improves an adhesive property between the storage electrode and a contact plug.

The conventionally used method is that the polysilicon layer and the contact plug for forming the storage electrode are bonded by a self align contact method. When using this method, the adhesion between the lower electrode, which is the storage electrode, and the contact plug is used. The weakened area is weakened, and in some cases, the bottom electrode is not lifted due to insufficient over etching during the lower electrode etching. As a result, the lower electrode does not adhere to the contact plug and falls off, thereby acting as a defect source that causes defects or defects. In addition, in the wafer edge region, as the step height increases, cap lifting occurs more severely, so that the die must be removed at the edge of the wafer to proceed the process. There is this.

Therefore, in order to solve the above problems, the present invention forms a primary storage electrode on the contact plug and then excessively etches the contact plug by an etch back process to form an inclined etching surface on the contact plug, thereby reducing the surface area. It is an object of the present invention to provide a method of forming a storage electrode of a capacitor capable of preventing a failure and improving an electrical property of a device by improving the adhesive property between the contact plug and the storage electrode by forming a secondary storage electrode in an increased state.

In the method of forming a storage electrode of a capacitor according to the present invention, after forming an interlayer insulating film on a semiconductor substrate having various elements for forming a semiconductor device, a first step of forming a contact hole to expose a junction of the semiconductor substrate, the semiconductor substrate After depositing a conductive material on the surface and performing chemical mechanical polishing, the second step of forming a contact plug by leaving the conductive material inside the contact hole only, and sequentially depositing a nitride film, a first oxide film and a second oxide film on the whole A third step of forming a trench to expose the contact plug by etching the second oxide film, the first oxide film, and the nitride film in a predetermined region; depositing a conductive material over the entire surface, and then performing an etch back to remain only on the trench sidewalls Remove the material to form the primary storage electrode and at the same time only the set depth on the contact plug A fourth step of forming an etched slope in the contact plug by over-etching, depositing a conductive material over the whole, and then removing the conductive material on the second oxide layer by chemical mechanical polishing to form a secondary storage electrode, thereby forming a primary storage electrode. And a fifth step of forming a storage electrode including the secondary storage electrode and a sixth step of removing all of the second oxide film.

In the second step, the conductive material is deposited using either polysilicon to a thickness of 900 to 1100 mm 3 or 1000 mm 3.

In the third step, the nitride film is deposited in any one of 130 to 170 mm thick or 150 mm thick, the first oxide film is deposited in any one of 900 to 1100 mm thick or 1000 mm thick, and the second oxide film is 8000 to 15000 mm thick. To be deposited. The etch back process is over-etched to a contact plug with a thickness of 100-1500 kPa to form the etch inclined surface in the contact plug.

In the fourth step, the metal material is deposited to a thickness of 100 to 1000 kPa, and in the fifth step, the metal material is deposited to a thickness of 100 to 500 kPa. In this case, the metal material uses polysilicon.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail.

1A to 1G are cross-sectional views of devices sequentially illustrated to explain a method of forming a storage electrode of a capacitor according to the present invention.

Referring to FIG. 1A, an interlayer insulating film 3 is formed and planarized on a semiconductor substrate 1 on which a transistor 2 having a predetermined structure is manufactured.

The transistor 2 has a general structure and includes a gate oxide film 2a, a doped polysilicon 2b, a tungsten silicide layer 2c, an antireflection film 2d, a hard mask 2e and a gate spacer 2f.

The interlayer insulating film 3 is formed by first depositing a BPSG having a good flow rate of a film to completely fill the process between the transistors 2, removing a step generated by the transistor 2, and then depositing a material such as TEOS on top thereof. do.

Referring to FIG. 1B, a predetermined region of the interlayer insulating layer 3 is etched by an etching process to form a contact hole 3a exposing a junction of the semiconductor substrate 1.

Referring to FIG. 1C, the conductive material is deposited on the entire upper portion so that the contact hole 3a is sufficiently buried, and then the chemical mechanical polishing is performed until the upper surface of the interlayer insulating film 3 is exposed. The contact plug 4 is formed by removing the material and leaving the conductive material only inside the contact hole 3a.

At this time, the conductive material is deposited using a thickness of 900 to 1100 하여 and ideally 1000 Å using polysilicon.

Referring to FIG. 1D, the nitride film 5, the first oxide film 6, and the second oxide film 7 are sequentially formed on the entire upper part, and then the second oxide film 7 and the first oxide film ( 6) and the nitride film 5 are etched to form the trench T so that the upper surface of the contact plug 4 is completely exposed.

At this time, the nitride film 5 is deposited to a thickness of 130 to 170Å, ideally deposited to a thickness of 150Å. In the process of etching the second oxide film 7, the first oxide film 6 is deposited to have a thickness of 900 to 1100 μs, and ideally, to have a thickness of 1000 μs. The second oxide film 7 is a sacrificial oxide film for determining the shape of the storage electrode to be formed in a subsequent process, and is deposited to a thickness of 8000 to 15000 kPa.

Referring to FIG. 1E, a first polysilicon layer 8a is deposited to form a storage electrode over the entirety including the contact plug 4.

At this time, the first polysilicon layer 8a is deposited to a thickness of 100 to 1000 mW.

Referring to FIG. 1F, the contact plug 4 is excessively etched by a set depth D on the contact plug 4 while removing the first polysilicon layer 8a so that only the sidewalls of the trench T remain in the etch back process. An inclined etching surface is formed in the surface to increase the surface area. Thereafter, after depositing the second polysilicon layer 8b on the entire surface including the inclined etching surface on the contact plug 4, the chemical mechanical polishing is performed until the surface of the second oxide film 7 is exposed. The second polysilicon layer 8b on the oxide film 7 is removed. Thereby, the storage electrode 8 which consists of the 1st and 2nd polysilicon layers 8a and 8b is formed.

At this time, the etch back process is performed such that excessive etching of about 100 to 1500 kPa occurs in the contact plug 4. This also eliminates the defect sources on the contact plug 4. The second polysilicon layer is deposited to a thickness of 100 to 500 GPa.

Referring to FIG. 1G, the second oxide film 7 is removed to form the storage electrode 8 in a cylindrical shape.

In the above process, an inclined etching surface is formed on the contact plug 4 due to the excessive etching of the etch back process, thereby increasing the contact area between the storage electrode 8 and the contact plug 4. As a result, the adhesion between the storage electrode 8 and the contact plug 4 is improved to reduce the lifting of the storage electrode 8.

Although not shown in the drawings, a capacitor is manufactured by forming a dielectric film and an upper electrode over the whole using known techniques.

As described above, the present invention increases the adhesion between the storage electrode and the contact plug, thereby reducing the defect of the device and improving the reliability of the process and the electrical characteristics of the device.

1A to 1G are cross-sectional views of devices sequentially shown to explain a method of forming a storage electrode of a capacitor according to the present invention.

<Description of the symbols for the main parts of the drawings>

1 semiconductor substrate 2a gate oxide film

2b: doped polysilicon 2c: tungsten silicide layer

2d: antireflection film 2e: hard mask

2f: gate spacer 2: transistor

3a: contact hole 3: interlayer insulating film

4: contact plug 5: nitride film

6: first oxide film 7: second oxide film

8a: first polysilylcone layer 8b: second polysilylcone layer

8: storage electrode

Claims (9)

A first step of forming an interlayer insulating film on a semiconductor substrate having various elements for forming a semiconductor device, and then forming contact holes to expose a junction of the semiconductor substrate; Depositing a conductive material on the semiconductor substrate and performing chemical mechanical polishing to form the contact plug by leaving the conductive material only inside the contact hole; A third step of sequentially depositing a nitride film, a first oxide film, and a second oxide film over the entire surface, and then etching the second oxide film, the first oxide film, and the nitride film in a predetermined region to form a trench for exposing the contact plug; After the conductive material is deposited on the entire surface, the material is etched back to remove the conductive material so that it remains only on the trench sidewalls to form a primary storage electrode, and at the same time, the substrate is over-etched by a predetermined depth above the contact plug. A fourth step of forming an etching slope; After depositing a conductive material on the whole, the conductive material on the second oxide film is removed by chemical mechanical polishing to form a secondary storage electrode, thereby forming a storage electrode including the primary storage electrode and the secondary storage electrode. The fifth step and And a sixth step of removing all of the second oxide film. The method of claim 1, In the second step, the conductive material is deposited using any one of a thickness of 900 to 1100 또는 or 1000 Å using polysilicon. The method of claim 1, In the step 3, the nitride film is deposited by any one of the thickness of 130 to 170 kHz or 150 Å thick. The method of claim 1, In the third step, the first oxide film is formed by depositing any one of a thickness of 900 to 1100 Å or a thickness of 1000 Å. The method of claim 1, And in the third step, depositing the second oxide layer to a thickness of 8000 to 15000 Å. The method of claim 1, The etch back process is a method of forming a storage electrode of a capacitor, characterized in that the etch inclined surface is over-etched in the contact plug with a thickness of 100 to 1500Å over the contact plug. The method of claim 1, The method of claim 4, wherein the metal material is deposited to a thickness of 100 to 1000 Å. The method of claim 1, In the fifth step, the metal material is deposited to a thickness of 100 to 500Å, the method of forming a storage electrode of a capacitor. The method according to claim 7 or 8, And the metal material uses polysilicon.