KR100434708B1 - Method for forming capacitor of semiconductor device - Google Patents

Abstract

The present invention discloses a method for forming a capacitor, and the disclosed method for forming a capacitor includes depositing an interlayer insulating film on a semiconductor substrate on which a predetermined underlayer is formed, and contact plugs contacting a predetermined portion of the substrate in the interlayer insulating film. Forming a sacrificial oxide film on the interlayer insulating film including the contact plug, etching the sacrificial oxide film to form a contact hole exposing the contact plug and an adjacent region thereof, and forming the contact hole; Depositing a first polysilicon film on a surface and a sacrificial oxide film, removing a portion of the first polysilicon film deposited on the sacrificial oxide film, and removing the sacrificial oxide film to form a lower electrode made of polysilicon And nitriding the lower electrode surface; and Y as a dielectric film on the nitrided lower electrode. Depositing an ON thin film, heat treating a substrate resultant on which the YON thin film is deposited, depositing a TiN film as a barrier film on the heat-treated YON thin film, and a second poly for upper electrode on the TiN film Depositing a silicon film and patterning a second polysilicon film, a TiN film, and a YON thin film to form the upper electrode. According to the present invention, by using a YON film having a high dielectric constant of about 25 as the material of the dielectric film, it is possible to easily secure the charge capacity required for stable device operation in accordance with high integration of the device.

Description

METHODS FOR FORMING CAPACITOR OF SEMICONDUCTOR DEVICE

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a capacitor of a semiconductor device, and more particularly, to a method for securing a charging capacity required for maintaining stable device operation.

It is well known that cell size is decreasing as the integration of semiconductor devices proceeds. However, the reduction of the cell size is accompanied by the reduction of the capacitor area, and the reduction of the capacitor area leads to the reduction of the charging capacity, and it is difficult to secure the charging capacity required to maintain the device operating characteristics with the existing capacitor structure. .

In order to secure a certain amount of charge capacity required for cell operation, high-integration devices currently in mass production include forming charge storage electrodes in various three-dimensional structures, using high-k dielectric materials as the dielectric film, or making the dielectric film as thin as possible. To form. This is based on the charge capacity of the capacitor being proportional to the electrode surface area and the dielectric constant of the dielectric film, and inversely proportional to the gap between the upper and lower electrodes, that is, the thickness of the dielectric film.

For example, the lower electrode of the three-dimensional structure such as cylinder, concave, and fin structures is intended to increase the charge capacity by expanding the electrode surface area, and dielectric films such as Ta ₂ O ₅ and BST are inherent. Increasing the charging capacity using the electroluminescent material, and the ONO film (oxide film / nitride film / oxide film) of the thin film is intended to increase the charging capacity by reducing the thickness of the dielectric film.

Here, since the method of reducing the thickness of the dielectric film has its limitation, recent efforts to increase the charging capacity have been made to increase the electrode surface area or to develop a dielectric film having a high dielectric constant, in particular, In addition, expansion has also shown various difficulties in the process, and various studies on new high-k dielectric materials are being actively conducted.

However, high dielectric materials, such as Ta ₂ O ₅ and BST, which have been proposed for increasing the charging capacity, have many problems to be solved, such as deterioration of the reliability of the capacitor because of their difficult formation. Therefore, since its use is difficult, there is a difficulty in securing a charge capacity of a predetermined amount or more required for cell operation in the prior art.

Accordingly, an object of the present invention is to provide a method for forming a capacitor of a semiconductor device capable of securing the charge capacity required for stable device operation, which is devised to solve the above problems.

1A to 1E are cross-sectional views illustrating processes of forming a capacitor of a semiconductor device in accordance with an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1 semiconductor substrate 2 bit line

3: interlayer insulating film 4: nitride film

5: first contact hole 6: contact plug

7: sacrificial oxide film 8: second contact hole

9: polysilicon film 10: lower electrode

11: YON thin film 12: TiN film

13: upper electrode 20: capacitor

In order to achieve the above object, the present invention, the step of depositing an interlayer insulating film on a semiconductor substrate on which a predetermined base layer is formed; Forming a contact plug in the interlayer insulating film, the contact plug being in contact with a predetermined portion of the substrate; Depositing a sacrificial oxide film on the interlayer insulating film including the contact plug; Etching the sacrificial oxide layer to form a contact hole exposing the contact plug and an adjacent region thereof; Depositing a first polysilicon film on the contact hole surface and the sacrificial oxide film; Removing a portion of the first polysilicon film deposited on the sacrificial oxide film; Removing the sacrificial oxide film to form a lower electrode made of polysilicon; Nitriding the surface of the lower electrode; Depositing a YON thin film as a dielectric film on the nitrided lower electrode; Heat-treating the substrate product on which the YON thin film is deposited; Depositing a TiN film as a barrier film on the heat treated YON thin film; Depositing a second polysilicon film for an upper electrode on the TiN film; And patterning the second polysilicon film, the TiN film, and the YON thin film so that the upper electrode is formed.

Here, the first polysilicon film is deposited by flowing SiH ₄ gas of 800 to 1200 sccm under a temperature of 500 to 550 ° C. and a pressure of 0.5 to 1 torr, and 100 to 300 kPa is deposited with a doped polysilicon film. Deposited with an undoped polysilicon film, and additionally flows a PH ₃ gas of 150-250 sccm when the doped polysilicon film is deposited.

The step of nitriding the surface of the lower electrode is NH ₃ plasma, and performing a process, the NH ₃ plasma process is 10~500sccm the amount of pressure the 0.1~1.2torr, NH ₃ gas in the 300~500 ℃, the chamber temperature of the substrate And 10 to 60 seconds under the condition that the RF power is 10 to 500W.

The depositing of the YON thin film is performed by a PECVD process, an ALD process or an ICE process, maintains the pressure in the chamber at 0.1 to 1.2 torr, maintains the substrate temperature at 250 to 500 ° C, and RF power to 10 to 500 W. Under the condition of flowing Yttrium gas into the chamber by a predetermined amount, NH ₃ gas and O ₂ gas, which is the reaction gas, were flowed about 10 to 100 sccm, respectively, and deposited to a thickness of 10 to 100 kPa.

Heat treating the result that the YON thin films is the nitrogen in the YON thin film (N ₂₎ an increased nitrogen while removing the carbon (C), and the impurities in step heat treatment for the content is increased and the YON thin film (N ₂₎ content It consists of a two-stage heat treatment to maintain.

The one-step heat treatment is performed by N ₂ O plasma heat treatment in which rapid heat treatment is performed for 60 to 180 seconds at a temperature of 700 to 850 ° C. while the N ₂ O gas amount is 1 to 10 slm. The two-stage heat treatment is performed by Furnace Vaccum N ₂ heat treatment at a temperature of 500 to 650 ° C. for 5 to 60 minutes, or by rapid heat treatment in an N ₂ atmosphere.

According to the present invention, by using a YON film having a high dielectric constant of about 25 as the material of the dielectric film, it is possible to easily secure the charging capacity required for stable cell operation in accordance with high integration.

(Example)

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

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

Referring to FIG. 1A, an interlayer insulating film 3 is deposited on a semiconductor substrate 1 provided with a predetermined base layer including a bit line 2, and a nitride film 4 is deposited on the surface thereof as a barrier film. . Then, a portion of the nitride film 4 and the interlayer insulating film 3 are locally etched to form a first contact hole 5 exposing a predetermined portion of the substrate 1, for example, a source region of the transistor.

Next, a plug conductive film, preferably a polysilicon film, is deposited on the nitride film 4 so that the first contact hole 5 is filled, and then overetch-back the polysilicon film. ) To form a contact plug 6 in the first contact hole 5.

Referring to FIG. 1B, a sacrificial oxide film 7 is deposited on the substrate resultant to have a thickness of 5000˜20000 μm to form a cylindrical lower electrode. Then, the sacrificial oxide film 7 is etched according to a known process to form a second contact hole 8 exposing the contact plug 6 and the nitride film portion adjacent thereto. Subsequently, a lower electrode conductive film, for example, a polysilicon film 9 is deposited on the surface of the second contact hole 8 and the sacrificial oxide film 7.

At this time, the polysilicon film 9 is deposited at a temperature of 500 to 550 ° C. and a pressure of 0.5 to 1 torr with an amount of SiH ₄ gas, which is a source gas, of 800 to 1200 sccm. It is deposited to a doped polysilicon film by flowing a PH ₃ gas about 150-250sccm, and deposited to an undoped polysilicon film about 100 ~ 500Å.

Referring to FIG. 1C, in a state in which a photoresist film (not shown) is applied to fill a second contact hole on the substrate resultant, a CMP (Chemical Mechanical Polishing) process is performed to remove the polysilicon film portion deposited on the sacrificial oxide film. Then, the remaining photosensitive film and the sacrificial oxide film are removed to form a lower electrode 10 having a cylinder structure. Here, the lower electrode 10 is simply formed in a cylindrical structure, but may also be formed in a three-dimensional structure such as a fin structure, in particular, hemispherical silicon may be formed on the surface to increase the charge capacity.

Next, the surface of the polysilicon lower electrode 10 is subjected to NH ₃ plasma treatment to nitride the surface thereof. Here, the NH ₃ plasma treatment is performed to prevent the interface failure between the lower electrode 10 and the YON film in the subsequent Yttrium oxide nitride (YON) thin film deposition and subsequent thermal process, preferably, the substrate temperature Is maintained at 300 to 500 ° C., the pressure in the chamber is maintained at 0.1 to 1.2 torr, and the RF power is 10 to 500 W while the amount of NH ₃ gas, the reaction gas, is 10 to 500 sccm, for 10 to 60 seconds. do.

Referring to FIG. 1D, any one selected from a Plasma Enhanced Chemcial Vapor Deposition (PECVD) process, an Atomic Layer Deposition (ALD) process, or an ionized cluster beam (ICE) deposition process, preferably, the lower electrode subjected to the nitriding treatment by a PECVD process A YON thin film 11 having a high dielectric constant of about 25 is deposited as a dielectric film on the substrate product including (10).

Here, the YON thin film 11 maintains the pressure in the chamber at 0.1 to 1.2 torr, the substrate temperature at 250 to 500 ° C, and the yttrium gas in the chamber under the condition of the RF power at 10 to 500W. While flowing by a predetermined amount, NH ₃ gas and O ₂ gas, which are reaction gases, are flowed about 10 to 100 sccm, respectively, and deposited by a thickness of about 10 to 100 kPa.

Then, N ₂ O plasma heat treatment is performed on the substrate resultant to increase the nitrogen (N ₂ ) content in the YON thin film 11. Here, the N ₂ O plasma treatment is performed by rapid thermal annealing, wherein the rapid heat treatment is performed by maintaining the temperature at 700 to 850 ° C. while keeping the amount of N ₂ O gas at 1 to 10 slm. Run for seconds.

Subsequently, to maintain the increased nitrogen (N ₂ ) content while removing carbon (C) and impurities in the YON thin film 11, at a temperature of 500 to 650 ° C. with respect to the N ₂ O plasma treated substrate resultant. Furnace Vaccum N ₂ heat treatment is performed for 5 to 60 minutes. Here, instead of the furnace vacuum N ₂ heat treatment, it is also possible to perform the rapid heat treatment of the N ₂ atmosphere.

Referring to FIG. 1E, a TiN film 12 is deposited on the YON thin film 11 as a barrier film. Then, after depositing an upper electrode conductive film, for example, a polysilicon film on the TiN film 12, the polysilicon film, the TiN film, and the YON thin film are formed so that the upper electrode 13 made of a polysilicon film is formed. Patterning is performed, and as a result, the capacitor 20 of the YON dielectric film according to the present invention is completed.

Here, the capacitor according to the present invention has a dielectric constant of about 4 to 6 by applying a YON thin film having a high dielectric constant of about 25 as a dielectric film and preventing degradation of the film itself and interfacial characteristics with the lower electrode through process development. Compared with the conventional capacitor to which the ONO film is applied, the charge capacity can be increased by increasing the dielectric constant, and thus, sufficient charge capacity required to maintain stable device operating characteristics can be secured very easily.

As described above, the present invention can very easily secure a certain amount or more of the charge capacity required for maintaining the device operating characteristics by using a high dielectric constant YON thin film as the dielectric film, and thus is very advantageous for the manufacture of highly integrated devices. Can be applied.

In addition, this invention can be implemented in various changes in the range which does not deviate from the summary.

Claims (13)

Depositing an interlayer insulating film on a semiconductor substrate on which a predetermined underlayer is formed; Forming a contact plug in the interlayer insulating film, the contact plug being in contact with a predetermined portion of the substrate; Depositing a sacrificial oxide film on the interlayer insulating film including the contact plug; Etching the sacrificial oxide layer to form a contact hole exposing the contact plug and an adjacent region thereof; Depositing a first polysilicon film on the contact hole surface and the sacrificial oxide film; Removing a portion of the first polysilicon film deposited on the sacrificial oxide film; Removing the sacrificial oxide film to form a lower electrode made of polysilicon; Nitriding the surface of the lower electrode; Depositing a YON thin film as a dielectric film on the nitrided lower electrode; Heat-treating the substrate product on which the YON thin film is deposited; Depositing a TiN film as a barrier film on the heat treated YON thin film; Depositing a second polysilicon film for an upper electrode on the TiN film; And And patterning a second polysilicon film, a TiN film, and a YON thin film so that the upper electrode is formed. The method of claim 1, wherein the depositing of the first polysilicon film is performed. A method for forming a capacitor of a semiconductor device, comprising depositing by flowing SiH ₄ gas of 800 to 1200 sccm under a temperature of 500 to 550 ° C. and a pressure of 0.5 to ₁ torr. The method of claim 1, wherein the depositing of the first polysilicon film is performed. A method of forming a capacitor of a semiconductor device, characterized in that 100 to 300 GHz is deposited with a doped polysilicon film, and 100 to 500 GHz is deposited with an undoped polysilicon film. The method of claim 3, wherein the deposition of the doped polysilicon film A method for forming a capacitor of a semiconductor device, comprising depositing a flow of SiH _{4 of} 800 to 1200 sccm and a flow of PH _{3 of} 150 to 250 sccm. The method of claim 1, wherein nitriding the lower electrode surface is performed. A method of forming a capacitor of a semiconductor device, characterized in that performed by NH ₃ plasma treatment. The method of claim 5, wherein the NH ₃ plasma treatment is A semiconductor device characterized in that it is carried out for 10 to 60 seconds under the conditions of a substrate temperature of 300 to 500 ° C, a pressure in the chamber of 0.1 to 1.2 torr, an amount of NH ₃ gas of 10 to 500 sccm, and an RF power of 10 to 500 W. Capacitor formation method. The method of claim 1, wherein depositing the YON thin film A method for forming a capacitor of a semiconductor device, characterized in that performed by any one process selected from the group consisting of PECVD process, ALD process and ICE process. 8. The method of claim 1 or 7, wherein depositing the YON thin film NH is a reaction gas while the pressure in the chamber is maintained at 0.1 to 1.2 torr, the substrate temperature is maintained at 250 to 500 ° C., and the yttrium gas is flowed into the chamber by a predetermined amount under the condition that the RF power is 10 to 500 W. _A method for forming a capacitor of a semiconductor device, characterized by depositing ₃ gas and O ₂ gas about 10 to 100 sccm, respectively, to a thickness of 10 to 100 kPa. The method of claim 1, wherein the heat treatment of the resultant on which the YON thin film is deposited, 1 step heat treatment to increase the nitrogen (N ₂ ) content in the YON thin film and two step heat treatment to maintain the increased nitrogen (N ₂ ) content while removing carbon (C) and impurities in the YON thin film A method of forming a capacitor of a semiconductor device. The method of claim 1, wherein the one-step heat treatment is performed by N ₂ O plasma heat treatment. The method of claim 10, wherein the N ₂ O plasma heat treatment A method of forming a capacitor of a semiconductor device, characterized in that the rapid heat treatment is carried out for 60 to 180 seconds at a temperature of 700 to 850 ° C while the amount of N ₂ O gas is 1 to 10 slm. The method of claim 9, wherein the two-step heat treatment Furnace vacuum (Furnace Vaccum) A method for forming a capacitor of a semiconductor device, characterized in that carried out by N ₂ heat treatment or rapid heat treatment of N ₂ atmosphere. The method of claim 12, wherein the furnace vacuum N ₂ heat treatment A method of forming a capacitor of a semiconductor device, characterized in that performed for 5 to 60 minutes at a temperature of 500 ~ 650 ℃.