KR20080019334A - Method of forming a thin layer and method of manufacturing a capacitor using the same - Google Patents

Abstract

A method for forming a thin film and a method for manufacturing a capacitor using the same are provided to obtain an excellent dielectric layer by improving surface uniformity on a substrate. A lower electrode(102) is formed on a plurality of substrates(100) which are positioned within a chamber(10). A precursor layer is formed on the lower electrode by supplying precursor gas including hafnium and zirconium onto the substrates. A first purge process is performed to purge the inside of the chamber. A dielectric layer(120) including a zirconium oxide is formed on the lower electrode by oxidizing the precursor layer. A second purge process is performed to purge the inside of the chamber. An upper electrode(130) is formed on the dielectric layer.

Description

Method of forming a thin layer and method of manufacturing a capacitor using the same

1 and 6 are cross-sectional views illustrating a capacitor manufacturing method according to an embodiment of the present invention.

7 is a configuration diagram illustrating a chamber in the form of a general vertical furnace.

Explanation of symbols on the main parts of the drawings

10 process chamber 100 semiconductor substrate

102: upper electrode 110: precursor gas

112 precursor film 114 oxidant

116 hafnium zirconium oxide film 120 dielectric film

130: upper electrode

The present invention relates to a thin film forming method and a capacitor manufacturing method using the same. More particularly, the present invention relates to a method of forming a dielectric film using atomic layer deposition and a method of manufacturing a capacitor using the same.

Recently, in semiconductor devices, thin films for applying to dielectric films of capacitors and the like have been formed using materials having high-k dielectrics. The reason is that although the thin film made of the material having the high dielectric constant has a thin equivalent oxide thickness (EOT), the leakage current frequently generated between the lower electrode and the upper electrode of the capacitor is sufficiently reduced. Because it can.

Therefore, recently, as the dielectric film of the capacitor, a thin film made of HfO ₂ or ZrO ₂ having a high dielectric constant and capable of sufficiently lowering the equivalent oxide film thickness has been used, and a multilayer thin film or an alloy thin film containing them is applied. have.

As an example, as disclosed in US Pat. No. 6,753,618, the dielectric film of the capacitor may be an aluminum oxide film, a tantalum oxide film, a zirconium oxide film, a hafnium oxide film, an alloy thin film containing hafnium-aluminum oxide, or an alloy containing lanthanum aluminum oxide. It includes a thin film. As disclosed in Korean Patent Laid-Open Publication No. 2004-0002818, the dielectric film of the capacitor is a hafnium oxide film, a zirconium oxide film, a tantalum oxide film, an aluminum oxide film, a titanium oxide film formed on the silicate interface layer with a high dielectric constant with a silicate interface layer. A triumium oxide film, a BST film or a PZT film.

On the other hand, with the recent increase in the degree of integration of semiconductor devices, the area occupied by unit cells is decreasing, and thus, it is not easy to secure a desired cell capacitance. As an example, in the case of a conventional MIS (Metal / Insulator / (poly) Silicon) capacitor, it is not easy to implement a desired equivalent oxide film thickness according to oxidation of a polysilicon film functioning as a lower electrode.

Accordingly, development of a capacitor having a MIM (Metal / Insulator / Metal) structure has been actively progressed. Examples of the electrode material of the capacitor include metal nitrides such as TiN, WN, TaN, and the like, and precious metals such as Ru, Pt, Ir, and the like. In particular, the capacitor of the RIR structure employing the Ru electrode is not easy to integrate, and therefore, the capacitor of the TIT structure employing the TiN attracts attention.

Meanwhile, in the dielectric film made of the high dielectric constant material, atomic layer deposition is mainly used in consideration of the step coverage and the electrical characteristics of the dielectric film. Recently, in the case of atomic layer deposition for forming the dielectric film, since the single sheet process is very poor in throughput, interest in batch processes that proceed simultaneously for a plurality of substrates is increasing. have.

In the case of the batch atomic layer deposition, a dielectric film containing only a hafnium oxide film or a zirconium oxide film has a problem of low dielectric constant or inferior surface uniformity during film formation. For example, a dielectric film including a hafnium oxide film has a low dielectric constant of about 20, thereby limiting the increase in charge capacity. However, since the dielectric film is amorphous, it is excellent in surface uniformity. On the other hand, the dielectric film including the zirconium oxide film has a high dielectric constant of about 40, but crystallization when the film is formed to increase the surface roughness has a problem in terms of surface uniformity. In other words, when using either a hafnium oxide film or a zirconium oxide film, it is difficult to obtain a dielectric film having a desired dielectric constant and excellent surface uniformity.

A first object of the present invention for solving the above problems is to provide a thin film formation method for improving the surface uniformity while having a desired dielectric constant when forming a thin film of an atomic layer unit.

A second object of the present invention is to provide a method of manufacturing a capacitor using the thin film forming method as described above.

According to an aspect of the present disclosure, a thin film forming method according to an aspect of the present invention provides a precursor gas including hafnium and zirconium on a plurality of substrates positioned inside a chamber to form a precursor film on the substrates. do. Primary purge the interior of the chamber. A hafnium zirconium oxide film is formed on the substrates by providing an oxidant on the substrates to oxidize the precursor film. The inside of the chamber is secondary purged. As a result, a thin film of atomic layer units can be formed.

When forming a thin film on the substrate as described above, as the hafnium precursor material Tetrakis Ethyl Methyl Amino Hafnium, Hf [N (CH ₃ ) (C ₂ H ₅ )] ₄ ) or hafnium butyl Oxide (Hafnium Butyloxide, Hf (O-tBu) ₄ ) may be used, and the zirconium precursor material is Tetrakis Ethyl Methyl Amino Zirconium, Zr [N (CH ₃ ) (C ₂ H ₅ )] ₄ ) or zirconium butyloxide (Zirconium Butyloxide, Zr (O-tBu) ₄ ) and the like can be used.

According to one embodiment of the present invention, in order to provide the precursor gas, a hafnium precursor gas may be provided on the substrate, and then, after the supply of the hafnium precursor gas is stopped, the zirconium precursor gas may be provided.

When providing the precursor gas as described above, a mixed gas of hafnium precursor gas and zirconium precursor gas may be used as the precursor gas.

Meanwhile, oxygen (O ₂ ), ozone (O ₃ ), water (H ₂ O), etc. may be used as the oxidizing agent, and the forming process may be performed at a temperature of 200 to 500 ° C. and 0.1 to 3.0 Torr. It can be carried out under pressure conditions.

According to a capacitor manufacturing method according to another aspect of the present invention for achieving the second object, i) to form a lower electrode on a plurality of substrates located inside the chamber. ii) providing a precursor gas including hafnium and zirconium on the substrates to form a precursor film on the lower electrode. iii) first purge the interior of the chamber; iv) providing an oxidant on the substrates to oxidize the precursor film to form a dielectric film comprising hafnium zirconium oxide on the lower electrode. v) secondary purge the chamber interior. vi) an upper electrode is formed on the dielectric layer;

According to an embodiment of the present invention, the lower electrode and the upper electrode are metal nitrides such as titanium nitride (TiN), tungsten nitride (WN), tantalum nitride (TaN), or rubidium (Ru), platinum (Pt), Each may be made of a noble metal such as iridium (Ir).

According to another embodiment of the present invention, the step of performing steps ii) to iii) repeatedly may be further performed.

According to the embodiments of the present invention as described above, by forming a hafnium zirconium oxide film on the substrate using a mixed gas of hafnium precursor gas and zirconium precursor gas, the problem of low dielectric constant through the zirconium oxide to solve the problem Through this, the problem of deterioration of surface uniformity due to crystallization can be prevented.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments and may be implemented in other forms. The embodiments introduced herein are provided to make the disclosure more complete and to fully convey the spirit and features of the invention to those skilled in the art. In the drawings, the thickness of each device or film (layer) and regions has been exaggerated for clarity of the invention, and each device may have a variety of additional devices not described herein. When (layer) is mentioned as being located on another film (layer) or substrate, an additional film (layer) may be formed directly on or between the other film (layer) or substrate.

1 to 6 are cross-sectional views illustrating a capacitor manufacturing method according to an embodiment of the present invention.

Referring to FIG. 1, a lower electrode 102 is formed on a substrate 100. If the lower electrode 102 is formed using polysilicon, the Si component contained in the polysilicon penetrates into the dielectric layer 120 when the subsequent dielectric layer 120 is formed. ), Which is not preferable because it deteriorates the surface area of the polysilicon and thus affects the equivalent oxide film thickness of the dielectric film to be subsequently formed. Therefore, the lower electrode 102 is preferably made of a metal nitride such as TiN, WN, TaN. The lower electrode 102 may be formed using chemical vapor deposition, atomic layer deposition, or the like. Alternatively, the lower electrode 102 may be made of a noble metal such as Ru, Pt, and Ir.

Subsequently, the substrate 100 having the lower electrode 102 is positioned in the process chamber 10. If the temperature in the process chamber 10 is less than about 200 ° C., the reactivity of the precursor gas and the oxidant provided in the process chamber 10 is not preferable, and the temperature in the chamber 10 is about 500 ° C. If it exceeds, the crystallization of the dielectric film 120 formed on the lower electrode 102 is not preferable. In particular, in this embodiment, since the atomic layer deposition is performed, it is not preferable because the temperature in the process chamber 10 exceeds about 500 ° C. because it shows the characteristics of chemical vapor deposition. Therefore, it is preferable to adjust the temperature in the process chamber 10 to about 200 to 500 ℃. In particular, it is most desirable to adjust the temperature in the process chamber 10 to about 300 ° C., because the properties of the atomic layer stacks appear best at temperatures of about 300 ° C. FIG. In addition, when the pressure in the process chamber 10 is less than about 0.1 torr, it is not preferable because the reactivity of the precursor gas, the oxidant, etc. provided in the process chamber 10 is not good, and the pressure in the process chamber 10 is not good. It is not preferable to exceed this 3.0torr because control of the process conditions is not easy. Therefore, it is desirable to adjust the pressure in the process chamber 10 to about 0.1 to about 3.0 torr.

The precursor gas 110 including the metal precursor is provided on the lower electrode 102 of the substrate 100 positioned in the process chamber 10 while the inside of the process chamber 10 is adjusted to the temperature and the pressure. do. At this time, the precursor gas 110 is provided in a gas state using a member such as a bubbler.

As shown, the process chamber 10 is very schematically illustrated, and only one substrate 100 is shown, but it is preferable that a plurality of substrates 100 are disposed in the process chamber 10. Do. This is because the productivity of the semiconductor device is greatly lowered when the sheet type is advanced. For example, a vertically shaped chamber extending in the vertical direction may be used as the process chamber 10, and the plurality of substrates 100 may be arranged in a boat extending in the vertical direction in the process chamber 10. Can be supported by.

7 is a configuration diagram illustrating a chamber in the form of a general vertical furnace.

Referring to FIG. 7, the vertical furnace-shaped chamber 200 discharges the reaction chamber and the unreacted gas generated during the deposition process and the process chamber 210 containing the substrate W and the process chamber 210. It includes a vacuum providing unit 250 for adjusting the pressure inside. The process chamber 210 includes a manifold 220 to which the reaction gas providing unit 260 is connected, an inner tube 214 and an outer tube 212 provided at an upper portion of the manifold 220. ). The inner tube 214 is provided with a boat 230 for supporting a plurality of substrates W, the boat 230 is moved up and down through the manifold 220 by an elevator (not shown). The vacuum provider 250 is connected to the manifold 220 through a vacuum line 252 connected to the manifold 220, a main valve 254 installed in the vacuum line 252, and a vacuum line 252. A vacuum pump 256. In addition, the gas nozzle 270 is connected to the gas providing unit 260 and extends in the vertical direction inside the inner tube 214. The gas nozzle 270 injects a reaction gas into the inner tube 214.

On the other hand, a large diameter silicon wafer having a diameter of 300mm may be used as the substrate (W). Specifically, in the case of using the wafer having the diameter of 300mm, productivity is achieved by using the vertical furnace-type chamber capable of processing 20 substrates per hour, compared to the sheet type, which processes 10 substrates per hour. It can be doubled. In addition, the longitudinal furnace-type chamber can reduce the equipment area by more than 60% compared to the existing sheet type equipment in the case of a 75-sheet capacity, and the equipment price is 1 billion compared to the sheet type equipment using three chambers. Abnormal reduction effect can also be obtained.

Referring back to FIG. 1, a mixed gas of hafnium precursor gas and zirconium precursor gas may be used as the precursor gas 110. For example, when the precursor film 112 including hafnium and zirconium is formed on the lower electrode 102, the precursor gas containing hafnium may be hafnium butyl oxide (Hf (OtBu) ₄ ), tetra Tetrakis Ethyl Methyl Amino Hafnium (TEMAH, Hf [N (CH ₃ ) (C ₂ H ₅ )] ₄ ), Tetrakis Di-Methyl Amino Hafnium; TDMAH, Hf [N ( CH ₃ ) ₂ )] ₄ ), Tetrakis Di-Ethyl Amino Hafnium; TDEAH, Hf [N (C ₂ H ₅ ) ₂ ] ₄ ), and the like, and precursors containing zirconium. Gases include zirconium butyl oxide (Zr (OtBu) ₄ ), tetrakis ethyl methylamino zirconium; TEMAZ, Zr [N (CH ₃ ) (C ₂ H ₅ )] ₄ ), tetrakis dimethylamino zirconium (Tetrakis Di-Methyl Amino Zirconium; TDMAZ, Zr [N (CH ₃ ) ₂ )] ₄ ), tetrakis diethylamino zir Konium (Tetrakis Di-Ethyl Amino Zirconium; TDEAZ, Zr [N (C ₂ H ₅ ) ₂ ] ₄ ) and the like can be used.

The vapor pressure of the precursor gas containing the tetrakisethyl methylamino hafnium (TEMAH) and the precursor gas containing the tetrakis ethylmethylamino zirconium (TEMAZ) is almost the same. In addition, when comparing the thermal stability of the TEMAH gas and the TEMAZ gas, the thermal stability is also almost the same because both gases decompose at about 140 ℃. Therefore, when forming a precursor film using the mixed gas including the hafnium precursor gas and the zirconium precursor gas, it is possible to form a precursor film having excellent dielectric constant without considering factors due to temperature change of each precursor material.

As such, by providing the mixed gas including the hafnium precursor gas and the zirconium precursor gas as the precursor gas 110 on the lower electrode 102, some of the precursor materials are chemically adsorbed on the lower electrode 102. A precursor film 112 in atomic layer units is formed.

In addition, when the precursor gas 110 is provided above the lower electrode 102, a hafnium precursor gas is provided on the substrate 100, and then the supply of the hafnium precursor gas is stopped, and then a zirconium precursor gas is supplied. In some embodiments, a portion of the precursor materials may be chemically adsorbed on the lower electrode 102 to form the precursor layer 112 in atomic layer units.

 Therefore, the precursor film 112 includes both the characteristics of having an improved surface uniformity by amorphous deposition when forming a single layer of hafnium oxide and having a relatively large dielectric constant of about 40 when forming a single layer of zirconium oxide. do. In addition, by mixing the hafnium precursor gas and the zirconium precursor gas properly, the dielectric constant may be adjusted to have a desired dielectric constant in the range of about 20 to about 40.

The remainder of the precursor material is either physically adsorbed on the chemically adsorbed precursor material or drifted within the process chamber 10.

Referring to FIG. 2, in order to remove the precursor gas remaining in the process chamber 10 from the process chamber 10, a purge gas is supplied into the process chamber 10 and the process chamber 10 is simultaneously supplied. Pump. Thus, the remaining precursor gas 110 is removed from the process chamber 10 together with the purge gas and some of the physically adsorbed hafnium and zirconium precursors are also removed.

Subsequently, the supply of the purge gas is stopped, and the inside of the process chamber 10 is pumped with high vacuum to remove the physically adsorbed metal precursor.

Referring to FIG. 3, an oxidant 114 is provided into the process chamber 10 to oxidize the precursor film 112. Accordingly, the dielectric film 116 in atomic layer units is formed on the lower electrode 102. Examples of the oxidant may be oxygen (O ₂ ), ozone (O ₃ ), water (H ₂ O), or the like.

Referring to FIG. 4, a secondary purge step of simultaneously supplying and purging the purge gas to remove the oxidant 114 remaining in the chamber 10, stops the supply of the purge gas, and stops the process chamber 10. The secondary pumping step of pumping is performed sequentially.

Referring to FIG. 5, the dielectric film 120 having a desired thickness may be completed on the lower electrode 102 by repeatedly performing the above-described steps of forming the dielectric film 116 in units of atomic layers.

Meanwhile, before the supply of the precursor gas 110 and the supply of the oxidant 114, the pre-flushing step of the precursor gas 110 and the pre-flushing step of the oxidant 114 may be further performed. This is done to form the flow characteristics of the source gas 110 and the oxidant 114 in laminar flow.

Referring to FIG. 6, after the dielectric film 120 is formed, plasma treatment or heat treatment is performed to improve electrical characteristics of the dielectric film 120. Specifically, the plasma treatment or heat treatment is performed to reduce the leakage current by densifying the dielectric layer 120.

The plasma treatment may be performed in a plasma atmosphere, such as O ₂ plasma, N ₂ plasma, the heat treatment may be performed in an O ₂ or O ₃ atmosphere.

Subsequently, an upper electrode 130 is formed on the dielectric layer 120. The upper electrode 130 may be made of substantially the same material as the lower electrode 102, and may be formed in substantially the same manner as the method of forming the lower electrode 102.

According to one embodiment of the present invention, by forming a precursor film on the lower electrode 102 by supplying a precursor gas containing hafnium and zirconium, by oxidizing the precursor film to form a hafnium zirconium oxide film 116 Zirconium oxide can solve the problem of low dielectric constant, and hafnium oxide can prevent the problem of lowering surface uniformity due to crystallization. Therefore, the surface uniformity and dielectric constant of the finally formed dielectric film 120 can be implemented at a desired level.

According to the present invention as described above, by forming a hafnium zirconium oxide film on the substrate using a mixed gas of hafnium precursor gas and zirconium precursor gas, the problem of low dielectric constant through zirconium oxide and the surface due to crystallization through hafnium oxide The problem that uniformity falls can be prevented. Accordingly, a hafnium zirconium oxide film in atomic layer units having a surface uniformity and a high dielectric constant is formed on the substrate, and finally an excellent dielectric film can be obtained.

As a result, a capacitor having a high dielectric constant material film having improved film surface uniformity and dielectric constant as the dielectric film can be formed on the substrate.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (9)

Providing a precursor gas comprising hafnium and zirconium on a plurality of substrates located within the chamber to form a precursor film on the substrates; First purging the interior of the chamber; Forming a hafnium zirconium oxide film on the substrates by providing an oxidant on the substrates to oxidize the precursor film; And And purging the inside of the chamber. The method of claim 1, wherein the hafnium precursor material is Tetrakis Ethyl Methyl Amino Hafnium, Hf [N (CH ₃ ) (C ₂ H ₅ )] ₄ ) or Hafnium Butyloxide, Hf ( O-tBu) ₄ ) wherein the zirconium precursor material is Tetrakis Ethyl Methyl Amino Zirconium, Zr [N (CH ₃ ) (C ₂ H ₅ )] ₄ ) or zirconium butyloxide (Zirconium Butyloxide, Zr (O-tBu) ₄ ) comprising a thin film forming method. The method of claim 1, wherein providing the precursor gas comprises: Providing a hafnium precursor gas on the substrate; And And stopping providing the hafnium precursor gas, and then providing a zirconium precursor gas. The method of claim 1, wherein in the providing of the precursor gas, a mixed gas of a hafnium precursor gas and a zirconium precursor gas is provided. The method of claim 1, wherein the oxidant comprises at least one selected from the group consisting of oxygen (O ₂ ), ozone (O ₃ ), and water (H ₂ O). The method of claim 1, wherein the steps are performed at a temperature of 200 to 500 ° C. and a pressure of 0.1 to 3.0 Torr. Iii) forming a lower electrode on a plurality of substrates located within the chamber; Ii) providing a precursor gas comprising hafnium and zirconium on the substrates to form a precursor film on the lower electrode; Iii) first purging the interior of the chamber; Iii) forming a dielectric film comprising hafnium zirconium oxide on the lower electrode by providing an oxidant on the substrates to oxidize the precursor film; Iii) secondary purging the interior of the chamber; And Iii) forming an upper electrode on said dielectric film. The group of claim 7, wherein the lower electrode and the upper electrode are formed of titanium nitride (TiN), tungsten nitride (WN), tantalum nitride (TaN), rubidium (Ru), platinum (Pt), and iridium (Ir). Capacitor manufacturing method characterized in that each made of at least one selected from. 8. The method of claim 7, further comprising repeatedly performing steps ii) to iii).

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