KR19990050038A - Plasma forming apparatus and capacitor forming method using the same - Google Patents

Abstract

The present invention relates to a plasma forming apparatus suitable for carrying out a low temperature heat treatment process on a dielectric covering a lower electrode and a method of forming a capacitor using the plasma forming apparatus. The plasma forming apparatus includes a body, a process gas inlet formed in the upper portion of the body, A lower electrode formed on a lower portion of the body and through which process by-products are exhausted, a lower electrode on which the semiconductor substrate is mounted, an upper electrode spaced apart from the lower electrode by a predetermined distance, An RF power generator, and an electromagnet formed on the outside of the body.

The method for forming a capacitor using the plasma forming apparatus of the present invention includes a step of forming a lower electrode on a semiconductor substrate, a step of forming a dielectric to cover the lower electrode, a step of forming a dielectric material on the dielectric material, And a step of forming an upper electrode so as to cover the dielectric material subjected to the heat treatment.

Therefore, in the present invention, the isotropic plasma processing can be performed on the dielectric of the capacitor by making the charged particles of the plasma have a motion component in a direction perpendicular to the acceleration direction and the acceleration direction by using a magnetic field. There is also an advantage in advancing the plasma heat treatment of the dielectric of the capacitor with a very high aspect ratio.

Description

Plasma forming apparatus and capacitor forming method using the same

The present invention relates to a plasma forming apparatus and a method of forming a capacitor using the same, and more particularly, to a plasma forming apparatus suitable for advancing a low temperature heat treatment process on a dielectric covering a lower electrode and a dielectric heat treatment method of a capacitor using the same .

Many researches have been conducted to increase the storage density so that the capacitor has a constant storage capacity even if the cell area is reduced due to the high integration of the semiconductor device. In order to increase the storage capacity, the capacitor is formed into a three-dimensional structure such as a stacked or trench, thereby increasing the surface area of the dielectric. However, the lamination capacitor or the trench capacitor is complicated in the manufacturing process and has a limitation in increasing the surface area of the dielectric. Therefore, by forming a dielectric with a high dielectric material such as tantalum oxide (Ta ₂ O ₅ ), PZT (Pb (Zr Ti) O ₃ ) or BST ((Ba Sr) TiO ₃ ) .

Since the dielectric material using the high-dielectric material is easy to be metallized and has a very unstable bonding state, the heat treatment process using the oxygen gas in a plasma state is performed in a separate plasma forming apparatus to strengthen the electrical characteristics and densify the bonding tissue do.

1 is a cross-sectional view of a plasma forming apparatus according to the prior art.

1, a conventional plasma forming apparatus includes a body 100, a process gas inlet 102 formed on the body 100, and an exhaust unit 104 through which process by-products are exhausted . A lower electrode 106 on which the semiconductor substrate 108 is mounted is provided in the body 100 and an upper electrode 110 is provided to be spaced apart from the lower electrode 106 by a predetermined distance. A power generator for supplying RF power to the lower electrode 106 and the upper electrode 110 is installed.

The dielectric process of the capacitor using the conventional plasma forming apparatus will be described.

Though not shown in the figure, tantalum oxide (Ta ₂ O ₃ ) is laminated on the lower electrode of a capacitor manufactured on a semiconductor substrate through a normal process to form a dielectric.

The tantalum oxide is formed by a PECVD (Plasma Enhanced Chemical Vapor Deposition) method or an LPCVD (Low Pressure Chemical Vapor Deposition) method. Ta (OC ₂ H ₅ ) ₅ and O ₂ gas react with each other to form Ta ₂ O ₅ .

At this time, in the tantalum oxide forming process, a large amount of impurities such as carbon or atomic carbon remains on the surface of the tantalum oxide layer, and the residual carbon component and the oxygen component of tantalum oxide (Ta ₂ O ₅ ) It is easy to be metallized. Here, the fact that the tantalum oxide layer to be used as the dielectric is metallized has a conductive property, so that leakage current may flow therethrough.

Therefore, in order to prevent this, a separate heat treatment process is performed in order to remove the atomic or radical carbon components remaining on the surface of the tantalum oxide layer in the conventional plasma forming apparatus.

First, a semiconductor substrate 108 having tantalum oxide formed thereon is placed on a lower electrode 106 of a conventional plasma forming apparatus 100, and then oxygen gas is supplied to the inside through a process gas injecting unit 102 And the supplied oxygen gas is ionized by the RF power to be brought into a plasma state in a space between the upper electrode 110 and the lower electrode 106. At this time, the heat treatment process is proceeded while appropriately adjusting the flow rate, pressure, RF power, temperature of the lower electrode, heat treatment time, etc. of the oxygen gas in the conventional plasma forming apparatus.

Through the above-mentioned heat treatment process, a large amount of atomic or radical carbon component remaining on the surface of the tantalum oxide layer on which the deposition process has been performed is transferred into CO ₂ form to prevent metallization of tantalum oxide, The electrical properties of the dielectric are enhanced by reducing the amount of impurities retained in the process chamber, and the bonding state of the highly unstable tantalum oxide becomes dense.

However, in the conventional plasma forming apparatus, the plasma is accelerated toward the lower electrode due to the self bias applied to the lower electrode, resulting in directionality.

Therefore, in the dielectric heat treatment process of the capacitor using the conventional plasma forming apparatus, the plasma is accelerated in one direction, and the plasma processing is not progressed to the side of the bent portion of the dielectric.

In order to solve the above problems, it is an object of the present invention to provide a plasma forming apparatus capable of performing a uniform plasma process on a dielectric covering a lower electrode of a capacitor, and a method of forming a capacitor using the plasma forming apparatus.

In the plasma forming apparatus and the capacitor forming method using the plasma forming apparatus of the present invention, uniform plasma processing is performed on a dielectric having a three-dimensional structure by reducing the anisotropy generated by accelerating charged particles in the plasma in a predetermined direction and forming a plasma having isotropy .

The plasma forming apparatus includes a body, a process gas inlet formed in the upper portion of the body, through which the process gas is injected, an exhaust portion formed in the lower portion of the body to exhaust the process byproduct, a lower electrode on which the semiconductor substrate is mounted, An RF power generator for applying RF power to the lower electrode and the upper electrode, and an electromagnet formed on the outer periphery of the body.

The method for forming a capacitor using the plasma forming apparatus of the present invention includes a step of forming a lower electrode on a semiconductor substrate, a step of forming a dielectric to cover the lower electrode, a step of forming a dielectric on the dielectric, And a step of forming an upper electrode so as to cover the dielectric material subjected to the heat treatment.

1 is a cross-sectional view of a plasma forming apparatus according to the prior art,

2 is a cross-sectional view of a plasma forming apparatus according to the present invention,

3 is a view illustrating a process for manufacturing a capacitor using the plasma forming apparatus of the present invention.

Description of the Related Art [0002]

100, 200. Plasma forming apparatus 102, 202. Process gas injection unit

104, 204. Evacuation portion 106, 206. Wafer seating portion

108, 208. Wafer 110, 210. Top electrode

212. Electromagnet 300. Semiconductor substrate

302. Impurity region 304. Gate insulating film

306. Gate electrode 308. Cap insulating film

310. Interlayer insulating film H1. Contact hole

312. Lower electrode 314. Dielectric

316. Upper electrode

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

FIG. 2 is a cross-sectional view of a plasma forming apparatus according to the present invention, and FIG. 3 is a view illustrating a process of manufacturing a capacitor using the plasma forming apparatus of the present invention.

As shown in FIG. 2, the plasma forming apparatus of the present invention includes a body 200, a process gas injection unit 202 formed on the body 200, and an exhaust unit 204 through which process by- Respectively. A lower electrode 206 on which the semiconductor substrate 208 is mounted is provided in the body 200 and an upper electrode 210 is provided to be spaced apart from the lower electrode 206 by a predetermined distance. A power generator for supplying RF power to the lower electrode 206 and the upper electrode 210 is provided. An electromagnet (212) is installed outside the body (200).

The heat treatment process for the dielectric of the capacitor of the present invention will be described using the above-described plasma forming apparatus of the present invention.

Although not shown in the figure, Ta (OC ₂ H ₅ ) ₅ and O ₂ gas are reacted with each other on a lower electrode of a capacitor fabricated on a semiconductor substrate through a normal process using a PECVD method or an LPCVD method to be used as a dielectric Tantalum oxide (Ta ₂ O ₅ ) is formed.

Since a large amount of impurities such as carbon or carbon remains on the surface of the tantalum oxide after the deposition process, the oxygen component of the tantalum oxide and the tantalum oxide, which is a dielectric, are likely to be metallized through the substitution reaction of the carbon component.

Therefore, in order to prevent this, a separate heat treatment process is performed to prevent metallization by removing the impurities remaining in the tantalum oxide layer to be used as a dielectric in the plasma forming apparatus of the present invention.

2, the tantalum oxide semiconductor substrate 208 of the plasma forming apparatus 200 of the present invention is placed on a substrate 201, and oxygen gas is supplied to the inside through the process gas injection unit 202, The oxygen gas is ionized by the RF power to be in a plasma state in a space between the upper electrode 210 and the lower electrode 206. [

When the charged particles in this plasma state have a motion component in the -Z direction and a magnetic field is applied in the Y direction or the -Y direction by the electromagnet 212 formed on the body 200, the Lorentz force , The charge carriers in the plasma state also have motion components in the X or -X direction perpendicular to the acceleration direction in the -Z direction.

That is, the plasma isotropic in not only the -Z direction but also the X-direction or the -X-direction, the plasma processing effect is sufficiently exhibited in terms of the dielectric of the three-dimensional structure.

Therefore, in the plasma forming apparatus of the present invention, the atomic or radical carbon component remaining on the surface of the tantalum oxide layer after completion of the vapor deposition process is converted into the CO ₂ form through the isotropic plasma treatment, thereby allowing the impurity content It also enhances the electrical properties of the dielectrics and tightens the bonding state of the highly unstable tantalum oxide.

The process of advancing the dielectric heat treatment process of the capacitor of the present invention by the above plasma heat treatment will be described in detail.

As shown in FIG. 3A, a lower electrode 312 is formed on a semiconductor substrate 300. Reference numeral 302 denotes an impurity region; 306, a gate electrode; 304, a gate insulating film; 308, a cap insulating film; 310, an interlayer insulating film;

The dielectric 314 is formed to cover the lower electrode 312 of the semiconductor substrate 300, as shown in FIG. 3B. Then, the semiconductor substrate on which the dielectric material 314 is formed is transferred into the plasma forming apparatus of the present invention, and a heat treatment process using plasma is performed in a temperature range of about 300 to 500 ° C. At this time, a mixed gas of O 2 and O 3, a mixed gas of O 2 and N 2, a N 2 O gas, a NO gas, or the like is used as the gas flowing into the body 200 through the process gas injecting unit 202.

As described above, when the heat treatment process is performed on the dielectric 314, the upper electrode 316 is formed on the dielectric 314 as shown in FIG. 3C.

As described above, in the plasma forming apparatus and the capacitor forming method using the plasma forming apparatus of the present invention, the charged particles of the plasma have kinetic components in a direction perpendicular to the acceleration direction and the acceleration direction, so that the isotropic plasma Processing can be performed.

Thus, there is an advantage in advancing the plasma heat treatment of the dielectric of the capacitor with a very high aspect ratio.

Claims (5)

The body, A process gas inlet formed in the upper portion of the body to inject the process gas, An exhaust unit formed at a lower portion of the body to exhaust process byproducts, A lower electrode on which the semiconductor substrate is mounted, An upper electrode spaced apart from the lower electrode at a predetermined interval, An RF power generator for applying RF power to the lower electrode and the upper electrode, And an electromagnet formed on the outer periphery of the body. The method according to claim 1, Wherein a mixed gas of O2 and O3, a mixed gas of O2 and N2, an N2O gas, a NO gas, or the like is used as a gas to be introduced into the process gas injection unit. A method of manufacturing a semiconductor device, comprising: a body; a process gas inlet formed in the upper portion of the body to inject a process gas; an exhaust unit formed in the lower portion of the body to exhaust process byproducts; An RF power generator for applying RF power to the lower electrode and the upper electrode, and an electromagnet formed on an outer side of the body, the process gas flowing into the body and being ionized, A method of forming a capacitor using a plasma forming apparatus that is affected by a magnetic field formed by an electromagnet to have an isotropic motion component not only in an acceleration direction but also in a direction perpendicular to the acceleration direction, Forming a lower electrode on a semiconductor substrate, Forming a dielectric to cover the lower electrode; A step of causing the dielectric body to have an isotropic plasma heat treatment in the plasma forming apparatus; And forming an upper electrode so as to cover the dielectric material subjected to the heat treatment. The method of claim 3, Wherein the process is performed at a temperature of 300-500 < 0 > C. The method of claim 3, Wherein the dielectric is a high dielectric material such as Ta ₂ O ₅ , BST, PZT, or the like.