KR100587086B1 - Method for forming capacitor of semiconductor device - Google Patents

Abstract

The present invention discloses a method for forming a capacitor of a semiconductor device. A method of forming a capacitor of a semiconductor device according to the present invention includes depositing a silicon nitride film and a cap oxide film sequentially on an interlayer insulating film and a semiconductor substrate on which a storage node contact made of polysilicon is formed in the interlayer insulating film; Etching the cap oxide layer and the silicon nitride layer to form a trench to expose a storage node contact; Depositing a first barrier layer made of a material having a high etching selectivity with respect to a cap oxide layer on any of the etching liquids on the trench and the cap oxide layer; Etching the first barrier layer to remove the portion of the first barrier layer deposited on the cap oxide layer and the storage node contact; Sequentially depositing a second barrier film made of a material having a high etching selectivity with a cap oxide film on the resultant TiN film and an optional etching solution; Removing the second barrier layer portion and the TiN layer portion deposited on the cap oxide layer; Removing the cap oxide film by wet etching using an etchant to form a storage electrode having a cylinder structure formed of a TiN film; And sequentially forming a dielectric film and a metal plate electrode on the TiN storage electrode, wherein the first and second barrier films penetrate the etchant below the storage electrode during wet etching to remove the cap oxide layer. In addition, the first barrier layer interposed between the silicon nitride layer and the storage electrode is removed.

Description

Method for forming capacitor of semiconductor device

1 to 3 are cross-sectional views for explaining conventional capacitor structures.

4 and 5 are cross-sectional views and photographs for explaining the conventional problem.

6A to 6F are cross-sectional views of processes for describing a method of forming a capacitor according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

60 semiconductor substrate 61 interlayer insulating film

62: storage node contact 63: silicon nitride film

64: cap oxide film 65: trench

66: first barrier 67: TiSix

68 TiN film 68a Storage electrode

69: second barrier 70: dielectric

71: plate electrode 80: capacitor

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 forming a capacitor of a semiconductor device capable of preventing the occurrence of defects due to the penetration of an etchant in employing a metal electrode and a cylinder structure.

Recently, since a nitride-oxide (NO) capacitor employing a silicon nitride film (Si3N4) as a dielectric material has shown a limit in securing a charge capacity required for a next generation DRAM (DRAM) product of 256M or more, as shown in FIG. The development of a capacitor having a silicon-insulator-silicon (SIS) structure in which a Ta2O5 film (ε = 25), an Al2O3 film (ε = 9), and an HfO2 film (ε = 20) is used as a single dielectric.

In FIG. 1, reference numeral 11 denotes a storage electrode made of doped polysilicon, 12 a dielectric made of a single high dielectric constant film, and 13 denotes a plate electrode made of doped polysilicon.

However, Ta2O5 film having a high dielectric constant has a problem of weak leakage current, Al2O3 film is limited in securing charge capacity because the dielectric constant does not differ from Si3N4 film, and HfO2 film having a relatively high dielectric constant has a low breakdown field strength and thus is repetitive. Since it is vulnerable to electric shock, there is a problem that reduces the durability of the capacitor.

Accordingly, when the DRAM is integrated with a fine metal wiring process of 100 nm or less, as shown in FIG. 2, HfO 2 / Al 2 O 3 / HfO 2 and Mf (Metal-Insulator-Metal) structures employing a metal-based electrode (TiN) may be used. A capacitor employing the same triple dielectric is being developed, and as shown in FIG. 3, the shape of the storage electrode is also changed from a concave structure to a cylinder structure in order to increase the effective area. .

2 and 3, reference numerals 21 and 31 denote TiN storage electrodes, 22 a triple dielectric of HfO2 / Al2O3 / HfO2, 23 a TiN plate electrode, 34 an interlayer insulating film, and 35 a storage electrode. The node contacts and 36 represent cap oxides, respectively.

However, in forming a storage electrode in a cylindrical structure while applying a metal material such as TiN, after forming the storage electrode, a wet etching process using a diluted HF solution or a NH4F + HF mixed solution is performed to remove the cap oxide layer. In this process, as shown in FIG. 4, along the path A through which the etchant penetrates the storage electrode 41, the silicon nitride film 47 which is an etching barrier with the storage electrode 41 of TiN is also formed. Penetrating along the path B between the interfaces, the loss of the storage node contact and interlayer insulating film made of polysilicon under the storage electrode, as shown in Figure 5, which will lead to failure in DRAM operation In addition, the bundles across the entire wafer surface are a major obstacle to manufacturing yield.

In FIG. 4, reference numeral 44 denotes an interlayer insulating film, and 45 denotes a storage node contact, respectively.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, the formation of a capacitor of a semiconductor device capable of preventing the occurrence of defects due to the penetration of the etchant during the formation of the storage electrode consisting of a cylinder structure while applying a metal-based material The purpose is to provide a method.                         

In addition, another object of the present invention is to provide a method for forming a capacitor of a semiconductor device capable of securing device characteristics and manufacturing yield by preventing defects caused by etching liquid penetration.

In order to achieve the above object, the present invention comprises the steps of depositing a silicon nitride film and a cap oxide film in turn on a semiconductor substrate formed with an interlayer insulating film and a storage node contact made of polysilicon in the interlayer insulating film; Etching the cap oxide layer and the silicon nitride layer to form a trench to expose a storage node contact; Depositing a first barrier layer made of a material having a high etching selectivity with respect to a cap oxide layer on any of the etching liquids on the trench and the cap oxide layer; Etching the first barrier layer to remove the portion of the first barrier layer deposited on the cap oxide layer and the storage node contact; Sequentially depositing a second barrier film made of a material having a high etching selectivity with a cap oxide film on the resultant TiN film and an optional etching solution; Removing the second barrier layer portion and the TiN layer portion deposited on the cap oxide layer; Removing the cap oxide film by wet etching using an etchant to form a storage electrode having a cylinder structure formed of a TiN film; And sequentially forming a dielectric film and a metal plate electrode on the TiN storage electrode, wherein the first and second barrier films penetrate the etchant below the storage electrode during wet etching to remove the cap oxide layer. The present invention provides a method of forming a capacitor of a semiconductor device, which is prevented and removed together except for a portion of a first blocking layer interposed between a silicon nitride film and a storage electrode.

The method of forming a capacitor according to the present invention may include: removing the portion of the first barrier layer deposited on the cap oxide layer and the storage node contact; and before depositing the TiN layer and the second barrier layer in sequence, the storage node contact. Forming a TiSix on the surface of the further comprises.

The first and second barrier films include a material film having a high etching selectivity with respect to a cap oxide film for a diluted HF solution or a NH4F + HF mixed solution, for example, an Al2O3 film, an HfO2 film, a TiO2 film, a ZrO2 film, and a Ta2O5 film. It is made of any one selected from, and deposited to a thickness of 10 to 100 kHz and 10 to 200 kHz, respectively.

The TiN film is deposited to a thickness of 200 to 400 GPa.

The wet etching to remove the cap oxide film is performed using a diluted HF solution or NH4F + HF mixed solution, proceeds with the silicon nitride film as an etch stop layer and the transient etching target (10-20%) And the etching selectivity between the oxide film and the nitride film is maintained at 5 to 20: 1.

The dielectric is a single structure consisting of any one selected from the group consisting of HfO 2, Ta 2 O 5, TiO 2 and La 2 O 3, or at least two or more using atomic layer deposition or pulsed-CVD processes. The multilayered structure is formed, or a three-component complex structure such as (HfO 2) x (Al 2 O 3) 1-x is formed.

The plate electrode is formed of any one selected from the group consisting of TiN, TaN, W, WN, Ru, RuO 2, Ir, IrO 2, and Pt.

(Example)

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

In general, when polysilicon is used as a storage electrode material, the polysilicon film itself is dense and has good adhesion to the silicon nitride film, which is an etching barrier, and thus, in the wet etching process for forming a storage electrode having a cylindrical structure. There is no problem in that the etching solution penetrates under the storage electrode and the storage node contact and the interlayer insulating film are lost. On the other hand, when a metal such as TiN is used as the storage electrode material, the film quality is not as dense as that of polysilicon due to the deposition of TiN as a columnar structure, and thus, the etching solution in the subsequent wet etching process. It can penetrate through the storage electrode of this TiN. In addition, not only the adhesion between the TiN film and the silicon nitride film (SiNx) is poor, but also when a shear stress is applied to the TiN, a path may be formed to facilitate the penetration of the etchant into the interface between the TiN film and the silicon nitride film. For this reason, the etchant may penetrate under the storage electrode.

Accordingly, the present invention is a material having a large wet etch selectivity with the cap oxide film before and after the deposition of the TiN film in order to employ a cylindrical electrode structure while employing a metallic material such as TiN as the storage electrode material, for example, Al2O3, HfO2 By forming a thin blocking layer made of TiO2, ZrO2, or Ta2O5, etc., a phenomenon in which the etching liquid penetrates to the lower portion of the storage electrode in the wet etching process for removing the cap oxide layer by the blocking film is prevented. Of course, the loss of the storage contact node and the interlayer dielectric layer due to the infiltrated etchant is prevented, and as a result, the device characteristics and manufacturing yield are ensured.

In detail, Figures 6a to 6f is a cross-sectional view for each process for explaining a capacitor forming method according to an embodiment of the present invention, as follows.

Referring to FIG. 6A, according to a known process, lower and lower patterns (not shown) including transistors and bit lines are formed, and a semiconductor substrate 60 having an interlayer insulating layer 61 is formed to cover the lower patterns. do. After that, the interlayer insulating layer 61 is etched to form a contact hole exposing a junction region or a landing plug poly (LPP), and then a polysilicon layer is embedded in the contact hole to form a storage node contact 62. Subsequently, the silicon nitride layer 63, which is an etch barrier, is deposited on the interlayer insulating layer 61 including the storage node contact 62 at a thickness of 200 to 800 占 by using an LPCVD, PECVD, or RTP apparatus. 63) Sources of PE-TEOS film, PSG film, BPSG film, and Si-H base at a thickness corresponding to the desired electrode height, e.g., electrode height required to obtain capacitor capacitance of 25 fF / cell or more. A used USG film or a cap oxide film 64 made of two or more types of multiple films is deposited.

Next, although not shown, a polysilicon film for a hard mask, an antireflection film, and a photoresist pattern for forming a storage electrode are sequentially formed on the cap oxide film 64.

Next, the anti-reflection film and the hardmask polysilicon film are sequentially etched using the storage electrode forming photoresist pattern, and then the etched hardmask polysilicon film and the remaining storage electrode formation photoresist pattern are used. The cap oxide film 64 is etched, and subsequently, the silicon nitride film 63 which is an etch barrier is etched to form a trench 65 for exposing the storage node contact 62. Here, in the process of etching the cap oxide film and the silicon nitride film, the photoresist pattern for forming the storage electrode, the anti-reflection film, and the polysilicon film for the hard mask are all removed. At this time, if the film is not removed in some cases, it is removed through an additional etching or cleaning process.

Subsequently, in the subsequent wet etching process on the trench 65 and the cap oxide layer 64 exposing the storage node contact 62, an etchant penetrates through an interface between the TiN storage electrode and the silicon nitride layer 63, which is an etching barrier. The first barrier film 66 is prevented from being deposited thinly, for example, in a thickness of 10 to 100 kPa. Here, the first barrier layer 66 may be a material film having a large etching selectivity with respect to the cap oxide film 64 with respect to an etching solution such as diluted HF solution or NH4F + HF mixed solution, for example, Al2O3 film, HfO2 film, TiO2 film, A ZrO 2 film or a Ta 2 O 5 film or the like is used.

Referring to FIG. 6B, the first barrier layer 66 is etched to remove the portion deposited on the cap oxide layer 64 and the portion deposited on the storage node contact 62 to remove the portion deposited on the storage node contact 62. ). Then, a thin film of Ti (not shown) is deposited on the resultant to make an ohmic contact between the polysilicon storage node contact 62 and the metal storage electrode to be subsequently formed. Annealing is performed to form TiSix 67 on the exposed surface of the storage node contact 62.

Referring to FIG. 6C, a TiN film 68, which is a storage electrode material, is deposited on a substrate resultant up to 200-400 mm thick, and then TiN storage is formed on the TiN film 68 in a subsequent wet etching process. In order to prevent the etching solution from penetrating the electrode and beneath the electrode, the etching solution, such as a diluted HF solution such as an Al 2 O 3 film, an HfO 2 film, a TiO 2 film, a ZrO 2 film, or a Ta 2 O 5 film or a mixed solution of NH 4 F + HF, may be used. A second blocking film 69 made of a material film having a large etching selectivity with respect to the cap oxide film 64 is deposited to a thickness of 10 to 200 mW.

Referring to FIG. 6D, after the photoresist film (not shown) is applied to the second blocking film 69 to a thickness of completely filling the trench 65, the photoresist film and the second blocking film (not shown) are exposed until the cap oxide film 64 is exposed. 69) and the chemical mechanical polishing (CMP) or etch-back (TiMP) film 68, thereby forming a storage electrode (68a) of TiN that can be separated from each other and independently store data.

Thereafter, a known photosensitive film strip (PR strip) process is performed to remove the photosensitive film remaining in the trench.

Referring to FIG. 6E, the storage electrodes 68a may be formed by performing a wet etching (Dip-Out) process using diluted HF solution or NH4F + HF mixed solution to obtain a storage electrode having a cylindrical structure. The cap oxide film remaining in between is removed. In this case, the wet etching process for removing the cap oxide film is performed by using the silicon nitride film 63 as an etch stop layer, and the transient etching target is 10 to 20%. In addition, the wet etching is performed by maintaining an etching selectivity ratio between the oxide film and the nitride film at 5 to 20: 1.

Here, during the wet etching, the second barrier layer deposited on the TiN storage electrode 68a is also removed. In this process, the second barrier layer penetrates through the TiN storage electrode 68a and enters under the etching solution. As the path is blocked, the etching liquid penetrates through the storage electrode 68a of the TiN and does not penetrate thereunder as in the related art.

In addition, during the wet etching, the first blocking layer 66 deposited on the TiN storage electrode 68a is removed together. At this time, the portion of the first blocking layer in contact with the cap oxide layer is removed, while the storage electrode of TiN is removed. The portion of the first blocking film interposed between 68a and the silicon nitride film 63 still remains. Therefore, the etching solution penetration path entering through the interface between the TiN storage electrode 68a and the silicon nitride layer 63 is blocked by the remaining first blocking layer 66. As described above, the TiN storage electrode 68a is blocked. Also, the etching solution penetrates under the storage electrode 68a of TiN through the interface between the silicon nitride layer 63 and the silicon nitride layer 63.

As a result, the present invention forms a barrier film that can block the penetration of the etching solution before and after the deposition of the storage electrode material TiN, so that the etching solution penetrates the storage electrode of TiN during wet etching to remove the cap oxide film, or TiN. It is possible to effectively prevent the penetrating under the storage electrode of TiN through the interface between the storage electrode of the silicon nitride film and the etching barrier, thereby preventing the loss of the storage node contact and interlayer dielectric layer under the storage electrode of TiN. As a result, device characteristics and manufacturing yield can be secured.

Referring to FIG. 6F, an atomic layer deposition or pulsed-CVD process is performed on a storage electrode 68a of TiN having a cylindrical structure such as HfO 2, Ta 2 O 5, TiO 2, or La 2 O 3. Single structure, dual structure such as HfO2 / Al2O3 or La2O3 / Al2O3 combined, triple structure such as HfO2 / Al2O3 / HfO2 or La2O3 / Al2O3 / La2O3, and three-component complex such as (HfO2) x (Al2O3) 1-x A dielectric 70 formed of a structure is formed. Then, a plate electrode 71 made of a metal material such as TiN is formed on the dielectric 70, and as a result, the capacitor 80 of the MIM structure according to the present invention is completed. In this case, the plate electrode 71 may be formed of a metal material such as TaN, W, WN, Ru, RuO 2, Ir, IrO 2, and Pt in addition to TiN, and may be formed to a thickness of about 200 to 500 μm.

As described above, the present invention forms an etching liquid penetration blocking film before and after the deposition of the electrode material in forming the storage electrode having a cylindrical structure made of a metal material, so as to the lower portion of the storage electrode in the subsequent cap oxide film removal process. It is possible to prevent the infiltration of the etchant and thus the loss of the storage node contact and the interlayer insulating layer, thereby securing device characteristics and manufacturing yield.

As mentioned above, although the present invention has been illustrated and described with reference to specific embodiments, the present invention is not limited thereto, and the following claims are not limited to the scope of the present invention without departing from the spirit and scope of the present invention. It can be easily understood by those skilled in the art that can be modified and modified.

Claims (12)

Depositing a silicon nitride film and a cap oxide film sequentially on an interlayer insulating film and a semiconductor substrate on which a storage node contact made of polysilicon is formed in the interlayer insulating film; Etching the cap oxide layer and the silicon nitride layer to form a trench to expose a storage node contact; Depositing a first barrier layer made of a material having a high etching selectivity with respect to a cap oxide layer on any of the etching liquids on the trench and the cap oxide layer; Etching the first barrier layer to remove the portion of the first barrier layer deposited on the cap oxide layer and the storage node contact; Sequentially depositing a second barrier film made of a material having a high etching selectivity with a cap oxide film on the resultant TiN film and an optional etching solution; Removing the second barrier layer portion and the TiN layer portion deposited on the cap oxide layer; Removing the cap oxide film by wet etching using an etchant to form a storage electrode having a cylinder structure formed of a TiN film; And And sequentially forming a plate electrode of a dielectric material and a metal on the storage electrode of TiN, The first and second barrier layers may be removed together with the exception of the first barrier layer interposed between the silicon nitride layer and the storage electrode while preventing the etchant from penetrating below the storage electrode during the wet etching process for removing the cap oxide layer. A method of forming a capacitor of a semiconductor device. The TiSix of claim 1, further comprising: removing the portion of the first barrier layer deposited on the cap oxide layer and the storage node contact; and before depositing the TiN layer and the second barrier layer in sequence, the TiSix layer on the surface of the storage node contact. Capacitor forming method of a semiconductor device, characterized in that it further comprises forming a. The method of claim 1, wherein the first and second blocking films are formed of a material film having a high etching selectivity with respect to the cap oxide film with respect to the diluted HF solution or the NH4F + HF mixed solution. 4. The capacitor formation of claim 1 or 3, wherein the first and second blocking films comprise any one selected from the group consisting of an Al2O3 film, an HfO2 film, a TiO2 film, a ZrO2 film, and a Ta2O5 film. Way. The method of claim 1, wherein the first and second blocking films are deposited to a thickness of 10 to 100 GPa and 10 to 200 GPa, respectively. The method of forming a capacitor of a semiconductor device according to claim 1, wherein the TiN film is deposited to a thickness of 200 to 400 GPa. The method of claim 1, wherein the wet etching to remove the cap oxide film is performed using a diluted HF solution or a mixed solution of NH 4 F + HF. 8. The wet etching method of claim 1 or 7, wherein the wet etching for removing the cap oxide film is performed by using the silicon nitride film as an etch stop layer and by using a transient etching target as 10 to 20%. A method of forming a capacitor of a semiconductor device. The method of claim 8, wherein the wet etching process for removing the cap oxide film is performed by maintaining an etching selectivity ratio between the oxide film and the nitride film at 5 to 20: 1. The monolithic structure of claim 1, wherein the dielectric is any one selected from the group consisting of HfO2, Ta2O5, TiO2, and La2O3 using an atomic layer deposition or pulsed-CVD process. Or Alternatively, at least two or more capacitor formation method of a semiconductor device, characterized in that formed in a multi-layer structure. The method of claim 1 or 10, wherein the dielectric is formed of a three-component complex structure of (HfO 2) x (Al 2 O 3) 1-x. The method of claim 1, wherein the plate electrode is made of any one selected from the group consisting of TiN, TaN, W, WN, Ru, RuO2, Ir, IrO2, and Pt.

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