KR20050029814A - Method for manufacturing ru layer and method for manufacturing mim capacitor using the same - Google Patents

Abstract

A method of fabricating Ru layer and a method of fabricating an MIM capacitor using the same are provided to minimize oxygen content within the ruthenium layer by forming the ruthenium layer by a PECVD(Plasma Enhanced Chemical Vapor Deposition) method or a PEALD(Plasma Enhanced Atomic Layer Deposition) method. A ruthenium layer(110) is formed on an upper surface of a semiconductor(100) by using a specific oxygen ruthenium source or plasma including hydrogen as a decomposer of a ruthenium source. The specific oxygen ruthenium source is formed with one of cyclopentadienyle type ruthenium sources such as Ru(EtCp)2 and Ru(BuCp)2. The plasma is formed with H2 plasma or NH3 plasma.

Description

Ruthenium film production method and method for manufacturing MIM capacitor using the same {Method for manufacturing Ru layer and method for manufacturing MIM capacitor using the same}

The present invention relates to a ruthenium film manufacturing method and a method of manufacturing a MIM capacitor using the same, and more particularly to a ruthenium film manufacturing method that can reduce the oxygen content of the ruthenium film used as a lower electrode and a method of manufacturing a MIM capacitor using the same It is about.

In recent years, ruthenium (Ru) or ruthenium compound which is extremely excellent in electrical characteristics, such as a resistivity, is applied as thin film electrode material of semiconductor elements, such as DRAM and FERAM.

Thin films of ruthenium (or ruthenium compound) are mainly formed by, for example, sputtering or chemical vapor deposition (CVD). In particular, since the CVD method has an advantage of easily manufacturing a thin film having a uniform thickness, it is mainly used to manufacture a highly integrated semiconductor device.

A ruthenium source is required to prepare a ruthenium thin film by the CVD method. Common ruthenium sources include Ru (EtCp) ₂ or Ru (BuCp) ₂ sources of cyclopentadienyle type and Ru (OD) ₃ or Ru (methd) _{3 of} non-diketonate type. Etc. Here, a method of manufacturing a MIM capacitor using a Ru film formed by a CVD method as an electrode will be described with reference to FIG. 1.

As shown in FIG. 1, an interlayer insulating layer 20 is formed on the semiconductor substrate 10. A conductive plug 25 is formed in a predetermined portion of the interlayer insulating film 20 in a known manner. A mold oxide film (not shown) is formed on the interlayer insulating film 20 on which the conductive plug 25 is formed. The interlayer insulating film 20 is etched to expose the surface of the conductive plug 25 to define the capacitor region.

Next, a cyclopentadienyl type Ru (EtCp) ₂ or Ru (BuCp) ₂ source and a non-diketonate type Ru (OD) ₃ or Ru (methd) _{3 on the} semiconductor substrate 10 having a limited capacitor region. A ruthenium film for the lower electrode is deposited by CVD using one source selected from among the sources. At this time, oxygen (O ₂ ) is used as a decomposer for decomposing the ruthenium source.

The ruthenium film deposited as described above is chemically mechanically polished to expose the mold oxide film surface, thereby forming a lower electrode 30 having a concave shape. Thereafter, the mold oxide film is removed in a known manner.

After depositing a dielectric film such as a tantalum oxide film 35 on the lower electrode 30 and the interlayer insulating film 20, a heat treatment process is performed to improve the dielectric constant of the tantalum oxide film 35. The upper electrode 40 is formed on the surface of the tantalum oxide film 35 with the same material as the lower electrode 30, thereby completing the capacitor 45.

However, as described above, since the ruthenium film constituting the lower electrode 30 uses oxygen as a decomposer for decomposing the ruthenium source, a large amount of oxygen is contained in the ruthenium film.

In particular, when using a ruthenium source of the cyclopentadienyl type, since the ruthenium source itself does not contain oxygen, the initial nucleation may be delayed. In order to prevent this, the ruthenium film is deposited under a high pressure and high oxygen atmosphere, but as the ruthenium film is deposited under a high oxygen atmosphere, the oxygen content of the ruthenium film is increased.

In addition, since ruthenium sources such as Ru (OD) ₃ or Ru (methd) ₃ of the non-diketonate type itself contain oxygen groups in the source, oxygen is inevitably included in the ruthenium film.

Most of this oxygen diffuses into the conductive plug 25 made of a titanium metal film at the bottom during the heat treatment process for improving the dielectric constant of the tantalum oxide film, thereby oxidizing the surface of the conductive plug 25. Here, reference numeral 50 denotes an oxide film generated at an interface between the conductive plug 25 and the lower electrode 30.

When the conductive plug 25 is oxidized in this manner, the contact resistance between the conductive plug 25 and the lower electrode 30 is increased, resulting in a resistive fail bit. In addition, the generation of the oxide film 50 between the contact plug 25 and the lower electrode 30 results in the formation of unwanted parasitic capacitors, thereby reducing the total capacitance of the capacitor.

Therefore, the technical problem to be achieved by the present invention is to provide a ruthenium film production method that can minimize the oxygen content.

In addition, another technical problem to be achieved by the present invention is to provide a method of manufacturing a MIM capacitor by the above-described ruthenium film manufacturing method that can prevent the oxidation of the conductive plug in contact with the lower electrode of the MIM capacitor.

In order to achieve the above technical problem, the ruthenium film production method of the present invention, by using a plasma containing a non-oxygen ruthenium source and a hydrogen component on the semiconductor substrate as a decomposer of the ruthenium source to produce a ruthenium film.

In addition, according to another aspect of the present invention, a method of manufacturing a MIM capacitor includes forming an interlayer insulating film having a conductive plug on a semiconductor substrate, and forming a mold oxide film over the interlayer insulating film. Thereafter, a portion of the mold oxide film is patterned to expose the conductive plug to form a capacitor region, and then a ruthenium film is formed by using a plasma including a non-oxygen ruthenium source and a hydrogen component to contact the conductive plug on the mold oxide film. Form. The ruthenium film is planarized to expose the mold oxide film to form a lower electrode, and the mold oxide film is removed. Thereafter, a dielectric film is formed on the lower electrode surface, and an upper electrode is formed on the dielectric film.

The conductive plug may be formed of a titanium metal film.

The non-oxygen ruthenium source may be one selected from ruthenium sources of cyclopentadienyl type, such as Ru (EtCp) ₂ and Ru (BuCp) _2, and the plasma containing the hydrogen component may be H ₂ plasma or NH. ₃ plasma.

In addition, the ruthenium film may be formed by a PECVD method or a PEALD method. In addition, when the ruthenium film is formed in the PEALD method, supplying the non-oxygen ruthenium source to the ALD chamber having a plasma atmosphere containing hydrogen for a predetermined time and purging the inside of the ALD chamber at least once. Repeat.

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

However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and the like of the elements in the drawings are exaggerated to emphasize a more clear description, and the elements denoted by the same reference numerals in the drawings means the same elements.

(Example 1)

2 is a cross-sectional view for explaining a ruthenium film production method according to Embodiment 1 of the present invention.

Referring to FIG. 2, a ruthenium film 110 is deposited using a non-oxygen ruthenium source on a semiconductor substrate 100, for example, on a silicon substrate product on which predetermined circuit patterns and insulating layers are formed. As the non-oxygen ruthenium source, a ruthenium source containing no oxygen component, for example, a ruthenium source of cyclopentadienyl type such as Ru (EtCp) ₂ , Ru (BuCp) ₂ and RuCpBuCp may be used. Meanwhile, as a decomposer for decomposing the non-oxygen ruthenium source, a plasma including a hydrogen (H) component, for example, an H ₂ plasma or an NH ₃ plasma may be used. Preferably, it may be formed by a plasma enhanced CVD (PECVD) method to continuously supply a plasma containing a hydrogen component during deposition of the ruthenium film 110 of the present embodiment.

Although the ruthenium film is deposited using a non-oxygen ruthenium source having a low initial nucleation rate, since the plasma containing a high activity hydrogen is used as the decomposer, the decomposition rate of the non-oxygen ruthenium source can be improved, thereby improving the nucleation rate. have. In addition, as the ruthenium film is formed by PECVD, the step coverage characteristics are superior to those of the conventional sputtering method.

(Example 2)

3 is a graph showing gas pulsing supplied to the ALD chamber according to Example 2 of the present invention.

In the ruthenium film according to the present embodiment, a plasma including a hydrogen component is used as a decomposer for decomposing the non-oxygen ruthenium source and the non-oxygen ruthenium source as in the first embodiment. In this embodiment, in order to continuously provide a plasma containing a hydrogen component, a ruthenium film is formed by a plasma enhanced atomic layer deposition (PEALD) method.

The ruthenium film manufacturing method according to the PEALD method, as shown in FIG. 3, periodically supplies a non-oxygen ruthenium source and a plasma atmosphere. More specifically, the non-oxygen ruthenium source is supplied for a predetermined time t1. As for the non-oxygen ruthenium source, a cyclopentadienyl type ruthenium source containing no oxygen component is supplied for a predetermined time as in Example 1 above.

After the supply of the non-oxygen ruthenium source is stopped, a purge process is performed for a predetermined time t2. During the purge process, components other than ruthenium of the non-oxygen ruthenium source are removed. After the purge process is completed, plasma is applied for a predetermined time t3. Applying the plasma is to create a plasma atmosphere inside the ALD chamber, which may be a plasma containing a hydrogen component, such as an H ₂ plasma or an NH ₃ plasma.

Next, the purge process is performed again for a predetermined time t4. In this manner, a process of supplying a non-oxygen ruthenium source, a purge process, and a process of applying plasma are alternately performed to deposit a ruthenium film having a predetermined thickness.

According to the present embodiment, since the ruthenium source does not contain oxygen and the decomposer also does not contain oxygen, the deposited ruthenium film has a very low oxygen content. In addition, since the ruthenium film of this embodiment is generally formed by the ALD method which proceeds at low temperature (200-300 degreeC), the damage to a ruthenium film by heat is reduced.

Figure 4 is a graph showing the composition of the ruthenium film formed by the ALD method using a non-oxygen ruthenium source and H ₂ plasma as a decomposer, Figure 5 is a decomposing the oxygen-containing ruthenium source and oxygen gas as in the prior art Is a graph showing the composition of a ruthenium film formed by the CVD method. The composition of the ruthenium film shown in FIGS. 4 and 5 is a result of analyzing by x-ray photoelectron spectroscopy (XPS) method, and the XPS method measures the amount emitted by sputtering photoelectrons to an inspection target (eg, ruthenium film). It is.

As in the present embodiment, the ruthenium film formed by the ALD method using the non-oxygen ruthenium source and the H ₂ plasma, except for a small amount of oxygen on the surface of the ruthenium film, as shown in the graph of FIG. Virtually no oxygen was observed).

On the other hand, when a ruthenium film is formed by a CVD method using an oxygen-containing ruthenium source such as a Ru (methd) 3 source and oxygen as a decomposer, as shown in FIG. 5, oxygen is widely distributed in the ruthenium film. In particular, it can be seen that a large amount of oxygen is distributed under the ruthenium film (corresponding to the interface between the ruthenium film and the conductive plug).

 As a result, as shown in the present embodiment, when the ruthenium film is formed by using a plasma containing a non-oxygen ruthenium source and a hydrogen component, it can be seen that the oxygen content in the ruthenium film is greatly reduced as compared with the prior art. In addition, when the ruthenium film is deposited by the PECVD method as in Example 1 described above, the result of FIG. 4 is also the same.

 (Example 3)

6A to 6C are cross-sectional views of respective processes for explaining a method of manufacturing a MIM capacitor according to Embodiment 3 of the present invention.

Referring to FIG. 6A, an interlayer insulating layer 210 is formed on a semiconductor substrate 200, for example, a silicon substrate on which a circuit element such as a transistor and an insulating layer are formed. The conductive plug 215 is formed in the interlayer insulating layer 210 by a known method so as to be electrically connected to the conductive region of the transistor. As a material of the conductive plug 215, a titanium nitride film having low reactivity with a ruthenium lower electrode to be formed later may be used. An etch stop layer 220 and a mold oxide layer 225 are sequentially stacked on the conductive plug 215 and the interlayer insulating layer 210. As the etch stop layer 220, for example, a layer having a different etching selectivity from the interlayer insulating layer 210 may be used, for example, a silicon nitride layer. The mold oxide layer 225 and the etch stop layer 220 are etched to expose the conductive plug 215 and the periphery thereof, thereby defining the capacitor region H.

Next, the ruthenium film 230 is deposited to a predetermined thickness using a plasma including a non-oxygen ruthenium source and a hydrogen component on the mold oxide film 225 and the capacitor region H as a decomposer. The ruthenium film 230 may be formed by PECVD or PEALD, as in Embodiments 1 and 2 described above. Since the ruthenium film 230 formed as described above is formed by a ruthenium source and a decomposer that does not contain oxygen, the oxygen content in the ruthenium film 230 is very low, especially at the interface between the ruthenium film 230 and the conductive plug 215. Oxygen distribution is significantly reduced.

Thereafter, a sacrificial layer (not shown) is formed on the ruthenium film 230 so as to fill the capacitor region H. Then, as shown in FIG. 225, by chemical mechanical polishing to expose the surface, to form the lower electrode 235. Thereafter, the sacrificial layer and the mold oxide film 225 are removed by a known wet etching method.

As shown in FIG. 4C, a dielectric film 240 is deposited on the surface of the lower electrode 235 and the surface of the etch stopper 220. The dielectric film 240 is an insulating film having a high dielectric constant, for example, a tantalum oxide film Ta ₂ O ₅ may be used. As is known, tantalum oxide films have an amorphous state at the time of deposition, and thus have a lower dielectric constant than when in a crystalline state. Accordingly, in order to improve the dielectric constant of the tantalum oxide film, the dielectric film 240 is heat-treated at a predetermined temperature. In this case, since the oxygen is almost not contained in the lower electrode 235, even when the heat treatment process is performed, oxygen does not diffuse to the conductive plug 215. Accordingly, oxidation of the conductive plug 215 can be prevented. Thereafter, the upper electrode 245 is formed on the surface of the dielectric film 240 to form the capacitor 250. In this case, the upper electrode 245 may be formed by the same material and method as the lower electrode 235. In addition, the upper electrode 245 may be formed of, for example, a noble metal film.

As described in detail above, according to the present invention, a ruthenium film is formed by PECVD or PEALD method using a non-oxygen ruthenium source and a plasma containing a hydrogen component as a decomposer during the deposition of the ruthenium film for the lower electrode. Accordingly, since oxygen supply is excluded when the ruthenium film is deposited, the oxygen content in the ruthenium film is minimized. Therefore, in the subsequent heat treatment step, oxygen diffusion to the conductive plug is prevented, and oxidation of the conductive plug is prevented.

Therefore, the contact resistance between the lower electrode and the conductive plug is reduced, and the capacitance of the capacitor is improved.

Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. .

1 is a cross-sectional view for explaining a method of manufacturing a general MIM capacitor.

2 is a cross-sectional view for explaining a ruthenium film production method according to Embodiment 1 of the present invention.

3 is a graph showing gas pulsing supplied to the ALD chamber according to Example 2 of the present invention.

Figure 4 is a graph showing the composition of the ruthenium film formed by the ALD method using a non-oxygen ruthenium source and H ₂ plasma decomposer as in the present embodiment.

FIG. 5 is a graph showing the composition of a ruthenium film formed by a CVD method using an oxygen-containing ruthenium source and an oxygen gas decomposer as in the related art.

6A to 6C are cross-sectional views of respective processes for explaining a method of manufacturing a MIM capacitor according to Embodiment 3 of the present invention.

(Explanation of symbols for the main parts of the drawing)

100, 200: semiconductor substrate 110, 230: ruthenium film

235 lower electrode 240 dielectric film

Claims (13)

And a ruthenium film is formed on a semiconductor substrate using a plasma containing a non-oxygen ruthenium source and a hydrogen component as a decomposer of the ruthenium source. The method of claim 1, wherein the non-oxygen ruthenium source is one selected from a ruthenium source of a cyclopentadienyl type such as Ru (EtCp) ₂ and Ru (BuCp) ₂ . The ruthenium film production method according to claim 1, wherein the plasma containing the hydrogen component is H ₂ plasma or NH ₃ plasma. The ruthenium film production method according to claim 1, wherein the ruthenium film is formed by PECVD. The ruthenium film production method according to claim 1, wherein the ruthenium film is formed by a PEALD method. The method of claim 5, wherein the ruthenium layer is formed by PEALD. Supplying the non-oxygen ruthenium source into an ALD chamber for a predetermined time; Purging the inside of the ALD chamber; And repeatedly providing at least one plasma including a hydrogen component to the ALD chamber. Forming an interlayer insulating film having a conductive plug on the semiconductor substrate; Forming a mold oxide film on the interlayer insulating film; Forming a capacitor region by partially patterning a mold oxide film to expose the conductive plug; Forming a ruthenium film on the mold oxide film by using a plasma including a non-oxygen ruthenium source and a hydrogen component to contact the conductive plug; Planarizing the ruthenium film to expose the mold oxide film to form a lower electrode; Removing the mold oxide film; Forming a dielectric film on the lower electrode surface; And And forming an upper electrode on the dielectric layer. 8. The method of claim 7, wherein the conductive plug is formed of a titanium metal film. The method of claim 7, wherein the non-oxygen ruthenium source is one selected from a cyclopentadienyl type ruthenium source such as Ru (EtCp) ₂ and Ru (BuCp) ₂ . 8. The method of claim 7, wherein the plasma containing the hydrogen component is H ₂ plasma or NH ₃ plasma. 8. The method of claim 7, wherein the ruthenium film is formed by PECVD. 8. The method of claim 7, wherein the ruthenium film is formed by a PEALD method. The method of claim 12, wherein the ruthenium film is formed by PEALD. Supplying the non-oxygen ruthenium source into an ALD chamber for a predetermined time; Purging the inside of the ALD chamber; Providing a plasma comprising a hydrogen component to the ALD chamber at least once.