KR100438673B1 - Method for fabricating capacitor - Google Patents

Abstract

The present invention is to provide a method of manufacturing a capacitor that does not require residue after etching or additional etching process to remove the platinum seed layer, the present invention for forming an insulating material on a semiconductor substrate, the insulating material Selectively etching to form a recess on which the storage node is to be formed, forming a metal substrate on the front surface including the recess, leaving a metal substrate only in the recess, and electroplating on the metal substrate. Forming a film to form a storage node made of the platinum film, a heat treatment step to increase the density of the platinum film, and forming a dielectric film and a plate node on the platinum film in sequence.

Description

Platinum film formation method using electroless plating method and manufacturing method of capacitor using same {Method for fabricating capacitor}

The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for manufacturing a capacitor.

Recently, as the degree of integration of memory devices increases, higher capacitance and smaller leakage current characteristics are required, thereby changing from ONO structure to metal-insulator-metal (MIM) structure with low leakage current.

In other words, a dielectric film having a high dielectric constant such as BST, Ta ₂ O ₅ , and Al ₂ O ₃ having a higher dielectric constant while being integrated is required, and a metal having a large work function is used to reduce leakage current. It must be applied as a lower electrode.

As the metal applied to the electrode, metals such as platinum (Pt), iridium (Ir), ruthenium (Ru), and TiN are used.

Particularly, in the case of TiN, Al ₂ O ₃ and Ta ₂ O ₅ are mainly used as dielectric films, and TiN is formed by chemical vapor deposition (CVD) using TiCl ₄ as a raw material.

However, TiN is oxidized during heat treatment for crystallization after Al ₂ O ₃ and Ta ₂ O _{5 are formed} by atomic layer deposition (ALD) or metal organic chemical vapor deposition (MOCVD). There is a disadvantage in that the reliability of the capacitor is lowered because it is limited by the subsequent heat treatment temperature.

In order to solve this problem, research is being conducted to apply ruthenium film (Ru) as a storage node. Ruthenium film is formed by metal organic chemical vapor deposition (MOCVD) mainly using metal organic materials as a raw material.

However, the ruthenium film deposited by metal organic chemical vapor deposition (MOCVD) has a characteristic that the film quality itself is not dense and the agglomeration phenomenon that occurs as it is changed under the mongol mongolia in a subsequent thermal process occurs and is not introduced into the capacitor manufacturing process. I can't.

Ruthenium films have very high interfacial properties with the Al ₂ O ₃ and Ta ₂ O ₅ dielectric films, providing high permittivity and low leakage current, but they are different from SrTiO ₃ and (Ba, Sr) TiO ₃ formed by metalorganic chemical vapor deposition (MOCVD). Due to the poor interfacial properties, it shows very high leakage current.

On the other hand, the platinum film has excellent interfacial properties with SrTiO ₃ and (Ba, Sr) TiO ₃ and is considered to be the most suitable electrode for these high-k dielectric films.

Platinum film having such advantages is formed by metal organic chemical vapor deposition method using a metal organic material as a raw material or by electroplating method using an electrolyte. Typically, the capacitor has a concave structure when the metal organic chemical vapor deposition method is used, and a convex structure when the electroplating method is used.

Platinum film using the metal organic chemical vapor deposition method is very difficult to apply to the fine design rule because the raw material is very expensive and the step coverage is poor in the concave for forming a storage node having a very high aspect ratio. On the other hand, the platinum film by the electroplating method does not have a problem of step coverage, but requires a platinum seed layer capable of applying current separately, and a process of removing the seed layer for shorting the storage node in a subsequent process.

However, since platinum is a precious metal that is difficult to be etched by wet or reactive ion etching, residues remain after etching.

The present invention has been made to solve the above problems of the prior art, an object of the present invention is to provide a method for manufacturing a capacitor that does not require residue after etching or additional etching process to remove the platinum seed layer.

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

* Explanation of symbols for the main parts of the drawings

11 semiconductor substrate 12 first insulating film

13: polysilicon plug 14: titanium silicide film

15 titanium nitride film 16 low dielectric constant insulating film

18 metal substrate 19 platinum film

20: dielectric film 21: upper electrode

A method of manufacturing a capacitor of the present invention for achieving the above object comprises the steps of forming an insulator on a semiconductor substrate, selectively etching the insulator to form a recess for forming a storage node, a metal on the front surface including the recess Forming a substrate, leaving a metal substrate only in the recess, forming a platinum film on the metal substrate by an electroless plating method to form a storage node made of the platinum film, to increase the density of the platinum film And a step of sequentially forming a dielectric layer and a plate node on the platinum layer, and forming the storage node of the platinum layer comprises H ₂ Pt (OH) ₆ and H ₂ PtCl. ₆ -6H ₂ O or H ₂ PtBr _6, and characterized by yirueojim in a platinum electrolyte solution formed from a -H ₂ O as a salt, wherein The pH of the platinum electrolyte solution is maintained at 1 to 5.5 or 7.5 to 13, the temperature is from room temperature to 95 ° C, and the concentration of platinum in the platinum electrolyte solution is 0.1 to 5 g / L. In the case of using acid, sulfosalicylic acid is used as a stabilizer, and the concentration of the stabilizer is 0.1 to 5 g / L, and 1,3,6-naphthalene, trisulfonic acid and triso are added to the platinum electrolyte solution. Dijon salt, 2,7- naphthalene disulfonic acid diso disulfide salt, benzene sulfonic acid or benzene disulfonic acid to add an additive, characterized in that the concentration of the additive is 0.1 to 5 g / L.

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. .

Platinum electroless plating is a method of forming the platinum ions dissolved in the electrolyte in a metal state on the substrate without applying an electric current, and it is important to ensure that the electrons necessary to form the platinum ions into the metal are secured on the substrate itself. . In the case of a metal substrate, platinum is deposited on the metal substrate as long as the metal can be dissolved in the electrolyte.However, in the case of using an insulator as a substrate, palladium is formed on the substrate in advance, which is then used as a nucleus for electron exchange and platinum formation. Apply the method used.

The present invention provides a method for selectively forming a storage node of a semiconductor device by applying an electroless plating method in which platinum is formed on a metal substrate.

On the other hand, the platinum electrolyte can be used in both acidic or basic, mainly H ₂ Pt (OH) ₆ as the basic, acidic H ₂ PtCl ₆ -6H ₂ O in a solvent in which the stabilizer is dissolved and then electrolyte use. When the metal substrate is put into the electrolyte, the surface of the metal substrate melts, the metal ions are dissolved in the electrolyte, and the electrons generated at this time are received by the platinum ions of the electrolyte and are formed on the surface of the metal substrate as platinum metal.

When the platinum metal is applied to the surface of the metal substrate, the electron exchange reaction no longer occurs, and the plating stops naturally after a certain time. Therefore, when the platinum film is formed by the electroless plating method, the thickness of the platinum film is naturally adjusted by controlling the concentration and temperature of the electrolyte.

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

As shown in FIG. 1A, a first insulating film 12 is deposited on a semiconductor substrate 11 on which transistors and bit lines (not shown) are formed. Here, the semiconductor substrate 11 is a silicon substrate, a doped polysilicon or an epitaxially grown silicon layer on which ion implantation is performed.

Next, the first insulating layer 12 is selectively etched to form a storage node contact hole (not shown) that exposes a portion of the surface of the semiconductor substrate 11. In this case, the storage node contact hole is a contact hole in which a storage node contact for vertically connecting the semiconductor substrate 11 and a capacitor is formed.

Next, the doped polysilicon film is deposited on the first insulating layer 12 by chemical vapor deposition (CVD) until the storage node contact hole is completely filled, and then recess-etched back to partially fill the storage node contact hole. The polysilicon plug 13 is formed.

Next, a titanium film is deposited on the entire surface including the polysilicon plug 13, and then heat-treated to induce a silicide reaction of the silicon atom of the polysilicon plug 13 and the titanium atom of the titanium film to form a titanium on the polysilicon plug 13. The silicide film 14 is formed.

Thereafter, the unreacted titanium film is wet-removed to leave the titanium silicide film 14 only on the polysilicon plug 13, and finally the remaining titanium silicide film 14 is formed to a thickness of 50 kPa to 500 kPa.

On the other hand, in order to stabilize the formation of the titanium silicide film 14, the titanium nitride film (TiN) may be further deposited by chemical vapor deposition or sputtering to a thickness of 100 kPa to 300 kPa immediately after the deposition of the titanium film.

Next, the titanium nitride film 15 is deposited on the first insulating film 12 to a thickness of 500 kPa to 2000 kPa until the storage node contact hole in which the titanium silicide film 14 is formed is completely filled, and then the first insulating film ( The titanium nitride film 15 is chemically mechanical polished (CMP) or etched back until the titanium nitride film 15 on 12 is removed, and only the titanium nitride film 15 is deposited on the titanium silicide film 14. ) Is left.

By the above-described process, the storage node contacts stacked in the order of the polysilicon plug 13, the titanium silicide layer 14 and the titanium nitride layer 15 are filled in the storage node contact hole, and the titanium silicide layer 14 Is an ohmic contact layer for lowering the contact resistance of the polysilicon plug 13 and the titanium nitride film 15, and the titanium nitride film 15 is formed by mutual connection between the subsequent storage node and the polysilicon plug 13. Diffusion barrier to prevent diffusion.

Meanwhile, cobalt silicide (Co-silicide) may be used in addition to titanium silicide as the ohmic contact layer. A titanium film or a cobalt film for forming silicide is deposited by chemical vapor deposition or sputtering.

As the diffusion barrier film, in addition to titanium nitride 15, one selected from the group consisting of TiSiN, TiAlN, TaSiN and TaAlN having excellent oxidation resistance is used, and the diffusion barrier layer is formed by chemical vapor deposition (CVD) or physical vapor phase. Deposition is via vapor deposition (PVD).

Next, a low dielectric constant insulating film 16 is formed on the first insulating film 12 including the titanium nitride film 15 to determine the height and structure of the subsequent storage node. Then, the low dielectric constant insulating film 16 is selectively formed. Etching is formed to expose the storage node contact, that is, to form a recess 17 for providing an electrical path between the storage node contact and the subsequent lower electrode.

Here, as the low dielectric constant insulating film 16, which is a material for forming the recess 17, glassy silicon oxide (USG, PSG, TEOS, HTO, PETEOS, SOG), a photoresist or a low dielectric constant polymer is used. The low dielectric constant insulating film 16 is formed by chemical vapor deposition (CVD), plasma chemical vapor deposition (PECVD), spin on glass (Spin On Glass), spray coating, plasma spray coating, or plasma spray coating. Vapor deposition in a thickness of 5000 kPa to 20000 kPa.

Before forming the low dielectric constant insulating film 16 described above, an insulating nitride (not shown) which can be used as an etch stop layer during the subsequent etching of the low dielectric constant insulating film 16 may be formed first, and the insulating nitride may be SiON, Si ₃ N _4. Is formed to a thickness of 100 kPa to 1000 kPa by chemical vapor deposition or reactive ion sputtering.

After the low dielectric constant insulating film 16 is formed, a high dielectric constant oxide film having a high etching selectivity with silicon, titanium nitride, and a low dielectric constant insulating film is used as a hard mask according to the thickness of the low dielectric constant insulating film 16. However, the dry reactive ion etching method or the wet method must be removed for further processing.

As shown in FIG. 1B, a metal substrate 18 is deposited on the entire surface of the low dielectric constant insulating film 16 including the recess 17.

At this time, the metal substrate 18 is formed of Ti, TiN, Ta, or TaN alone or in multiple layers thereof by a thickness of 50 kPa to 300 kPa through metal organic chemical vapor deposition (MOCVD) or atomic layer deposition.

Next, the metal substrate 18 is etched back or chemical mechanically polished (CMP) to remove the metal substrate 18 on the low dielectric constant insulating film 16 and to leave the metal substrate 18 only in the recess 17. .

Next, a platinum film 19 is formed on the metal substrate 18 remaining in the recess by electroless plating, wherein the platinum film 19 is formed to a thickness of 50 kPa to 300 kPa.

Here, the platinum electrolyte solution for applying the electroless plating method in which the platinum film 19 is formed on the metal substrate 18 may be used in both acidic or basic forms. H ₂ Pt (OH) ₆ , H ₂ PtCl ₆ -6H ₂ A solution formed using O or H ₂ PtBr ₆ -H ₂ O as the salt is used.

The pH of the platinum electrolyte solution is maintained at 1 to 5.5 or 7.5 to 13, the temperature is from room temperature to 95 ° C, and the concentration of platinum in the platinum electrolyte solution is 0.1 to 5 g / L.

On the other hand, when acidic is used as the platinum electrolyte solution, sulfosalicylic acid is used as a stabilizer, and the concentration of such stabilizer is 0.1 to 5 g / L. In addition, 1,3,6-naphthalene (naphthalene), trisulphonic acid (trisulphonic acid), trisodium salt, 2,7-naphthalene disulfonic acid disodis salt (naphthalene disulphonic) as an additive to the acidic platinum electrolyte solution acid disodium salt), benzenesulphonic acid or bezene disulphonic acid are used as additives, and the concentration of these additives is 0.1 to 5 g / L.

Next, after forming the platinum film 19 by the electroless plating method, it heat-processes for 30 second-30 minutes in nitrogen or argon atmosphere and the temperature of 450 degreeC-700 degreeC, in order to raise density.

Next, after the platinum film 19 is formed, the surface is immersed in a hydrogen peroxide solution containing sulfuric acid for 1 to 3 minutes before the dielectric film is formed.

As illustrated in FIG. 1C, the dielectric film 20 and the plate node 21 are sequentially deposited on the entire surface including the platinum film 19.

In this case, the dielectric film 20 is deposited by metal organic chemical vapor deposition (MOCVD) or atomic layer deposition (ALD), and is selected from the group consisting of SrTiO ₃ , (Ba, Sr) TiO ₃ , and (Pb, Sr) TiO ₃ . Using the selected one, it is deposited to a thickness of 80 kPa to 300 kPa. Then, crystallization is performed to improve the quality of the dielectric film 20 after deposition, and heat treatment for 10 minutes to 30 minutes at a temperature of 400 ° C. to 800 ° C. with an N ₂ O or N ₂ / O ₂ atmosphere or for 30 seconds to 10 minutes. Plasma treatment.

Then, the plate node 21 is deposited by using a metal organic chemical vapor deposition (MOCVD) or atomic layer deposition (ALD) selected from the group consisting of ruthenium, platinum and iridium to a thickness of 100 ~ 300Å, and further One selected from the group consisting of ruthenium, platinum and iridium is deposited to a thickness of 500 kV to 1000 kV by the sputtering method.

Then, after forming the plate node 21, in order to stabilize the capacitor structure, 30 N at an atmosphere of N ₂ / O ₂ or Ar / O ₂ mixed gas, a single gas of N ₂ or Ar, and a temperature of 500 ° C. to 800 ° C. Heat-treat for seconds to 60 minutes.

In the above-described embodiment, the low dielectric constant insulating film was left without removing, but the metal substrate was left only in the concave portion, and then the low dielectric constant insulating film was removed to implement a cylindrical structure or the low dielectric constant insulating film was removed by a predetermined thickness. Implement the structure to increase capacity.

At this time, when removing part or all of the low dielectric constant insulating film, the metal substrate is removed by a wet method so as not to collapse, and when part of the low dielectric constant insulating film is removed, the thickness is 4000 kPa to 18000 kPa.

As described above, the present invention is not limited to the above-described embodiments and the accompanying drawings, and the present invention may be variously substituted, modified, and changed without departing from the spirit of the present invention. It will be apparent to those of ordinary skill in Esau.

In the present invention described above, when a SrTiO ₃ , (Ba, Sr) TiO ₃ , and (Pb, Sr) TiO ₃ are used as a dielectric film, the platinum film is etched or electrically formed by forming a storage node made of a platinum film using an electroless plating method. There is no need for a seed layer for the plating method, thereby improving the characteristics of the capacitor.

Claims (8)

Forming an insulator on the semiconductor substrate; Selectively etching the insulator to form a recess in which a storage node is to be formed; Forming a metal substrate on the front surface including the recess; Leaving a metal substrate only in the recess; Forming a platinum film on the metal substrate by an electroless plating method to form a storage node made of the platinum film; A heat treatment step of increasing the density of the platinum film; And Sequentially forming a dielectric film and a plate node on the platinum film Method for producing a capacitor, characterized in that comprises a. The method of claim 1, Forming the storage node of the platinum film, A method for producing a capacitor, characterized in that the platinum electrolyte solution formed using H ₂ Pt (OH) ₆ , H ₂ PtCl ₆ -6H ₂ O or H ₂ PtBr ₆ -H ₂ O as a salt. The method of claim 2, The pH of the platinum electrolyte solution is maintained at 1 to 5.5 or 7.5 to 13, the temperature is from room temperature to 95 ℃, the concentration of the platinum in the platinum electrolyte solution is 0.1 to 5g / L method of producing a capacitor. The method of claim 2, When acid is used as the platinum electrolyte solution, sulfosalicylic acid is used as a stabilizer, and the concentration of the stabilizer is 0.1 to 5 g / L. The method of claim 4, wherein 1,3,6-naphthalene, trisulfonic acid, trisodidec salt, 2,7-naphthalene disulfonic acid diso disulfide salt, benzene sulfonic acid or benzene disulfonic acid are added to the platinum electrolyte solution. The concentration of is 0.1 to 5g / L method for producing a capacitor. The method of claim 1, The platinum film is formed in a thickness of 50 kPa to 300 kPa. The method of claim 1, In the step of forming a storage node of the platinum film, The heat treatment is carried out for 30 seconds to 30 minutes in a nitrogen or argon atmosphere and a temperature of 450 ℃ to 700 ℃, After the heat treatment, the platinum film is immersed in a hydrogen peroxide solution containing sulfuric acid for 1 to 3 minutes for surface treatment. Method of manufacturing a capacitor, characterized in that further comprises. The method of claim 1, The metal substrate is a single film of Ti, TiN, Ta or TaN or a multilayer film thereof, the method of manufacturing a capacitor, characterized in that formed in a thickness of 50 ~ 300Å.