KR20070031503A - Cylinder-typed capacitor and method of manufacturing the same - Google Patents

Abstract

Disclosed are a cylindrical capacitor and a method of manufacturing the same in which the lower electrode is not tilted. The cylinder capacitor has a lower electrode on a substrate. And a support structure formed on the substrate provided with the lower electrode and supporting a side surface of the lower portion of the lower electrode. A dielectric film having a substantially uniform thickness is provided on the lower electrode and the support structure, and an upper electrode is provided on the dielectric film. The lower electrode of the cylindrical capacitor may include a support structure to prevent the lower electrode from being inclined.

Description

Cylindrical Capacitor and Method of Manufacturing the Same {Cylinder-typed capacitor and method of manufacturing the same}

1 is a cross-sectional view showing a cylindrical capacitor according to an embodiment of the present invention.

2 to 8 are cross-sectional views illustrating a method of manufacturing the cylindrical capacitor shown in FIG. 1.

<Explanation of symbols for the main parts of the drawings>

100 substrate 102 device isolation film

104: gate 106: source, drain

108a: first pad electrode 108b: second pad electrode

110: bit line 112: second interlayer insulating film

114: contact plug 116: etching stop film pattern

117: mold film 117a: upper mold film

117b: lower mold film 118: mold film pattern

118a: Lower mold film pattern 118b: Upper mold film pattern

120: opening 122: conductive film

122a: lower electrode 124: sacrificial film

124a: sacrificial film pattern 126: dielectric film

128: upper electrode

The present invention relates to a cylindrical capacitor and a method of manufacturing the same, and more particularly to a method of manufacturing a cylindrical capacitor having improved structural stability.

In general, a capacitor included in a DRAM element or the like is composed of a lower electrode, a dielectric film, an upper electrode, and the like. In order to improve the capacity of a memory device including such a capacitor, it is very important to increase the capacitance of the capacitor.

At present, in order to secure the capacitance of the capacitor while decreasing the allowable area per unit cell as the integration level of the DRAM device increases to the giga level or more, the shape of the capacitor is initially manufactured to have a flat structure, and gradually increases the aspect ratio. It is formed in the box shape or cylinder shape which has (aspect ratio). Such a cylindrical capacitor is formed using a mold film made of an oxide in general. However, the etching process for removing the mold layer made of the oxide causes a capacitor failure such as a 2-bit fail between adjacent capacitors.

A method of manufacturing a capacitor using a conventional mold film will be described. A lower electrode of a cylinder type is formed on a semiconductor substrate to be adjacent to each other with a high aspect ratio compared to a width. In particular, an interlayer insulating film including a contact plug is formed on the semiconductor substrate, and the lower electrode of the cylinder type is connected to the contact plug.

Specifically, the formation of the lower electrode may be performed by depositing an etch stop layer made of nitride and a mold film made of oxide, forming a photoresist pattern on the substrate on which the contact region is formed, and then patterning the pattern formed on the interlayer insulating film. An opening is formed to expose the contact plug. The mold layer may be formed by sequentially stacking a first oxide of PLA-TEOS (Plasma Enhanced Tetra Ethyl Ortho Silicate) on the etch stop layer and a second oxide of BPSG (Boron Phosphorus Silicate Glass) on the first oxide. have.

Subsequently, the photoresist pattern is removed by an ashing and cleaning process, and then a lower electrode conductive film is formed on the exposed upper surface of the contact pad, the inner wall of the opening, and the mold film. Subsequently, in order to form a lower electrode of the capacitor having a cylindrical shape, a chemical mechanical polishing (CMP) process for separating the capacitor nodes is performed. At this time, a sacrificial film made of an oxide for use as a buffer of the chemical mechanical polishing process is formed on the conductive film. The cylindrical lower electrode is completed through the capacitor node separation process of planarizing the sacrificial layer until the mold layer is exposed. In this case, the sacrificial film pattern and the mold film remaining inside the cylindrical lower electrode are removed.

Wet etching is performed to remove the mold layer formed of the oxide left after the capacitor node is separated. However, the etching chemical used in the wet etching process may easily penetrate into the interface between the lower electrode and the etch stop layer to react with the interlayer insulating layer made of an oxide having the contact plug formed therein. Therefore, the etching causes voids in the interlayer insulating film, thereby causing a problem of destabilizing the base of the lower electrode thereon.

In addition, the lower electrode is inclined to one side due to surface tension generated by the etching solution on the surface of the lower electrode, thereby causing a problem.

Accordingly, an object of the present invention is to use the amorphous carbon film, polyaniline ether film or photoresist film in place of the existing oxide on the top of the mold film and to remove it by an ashing process to prevent the etching problem of the interlayer insulating film by wet etching, To provide a cylindrical capacitor comprising a structure for supporting the lower side of the lower electrode.

Another object of the present invention is to provide a method of manufacturing a cylindrical capacitor including the structure.

Cylindrical capacitor according to an embodiment for achieving the object of the present invention includes a lower electrode on the substrate. It is provided with a support structure for supporting the side of the lower portion of the lower electrode. And a dielectric layer formed continuously on the lower electrode and the support structure. The upper electrode is formed on the dielectric layer. As an example, the support structure is formed to have a height of 0.05 to 0.3 times the height of the lower electrode to fix the lower electrode so as not to tilt.

In addition, the cylindrical capacitor manufacturing method according to an embodiment of the present invention for achieving the other object described above forms a mold film consisting of a lower mold film and an upper mold film on a substrate. A mold film pattern having an opening for exposing the substrate is formed. A conductive film for the lower electrode is continuously formed on the sidewalls and the bottom surface of the opening and the upper surface of the mold layer pattern. A sacrificial film made of photoresist is formed on the resultant having the conductive film for the lower electrode to sufficiently fill the opening. Until the surface of the mold layer pattern is exposed, the sacrificial layer and the conductive layer for the lower electrode on the mold layer pattern are etched to form a lower electrode having the sacrificial layer pattern left therein. By removing the sacrificial layer pattern and the upper mold layer of the mold layer pattern, a lower electrode exposed on the substrate and a support structure for supporting a lower side of the lower electrode are formed. A dielectric film having a substantially uniform thickness is formed on the lower electrode and the support structure. An upper electrode is formed on the dielectric layer. As a result, a cylindrical capacitor is completed.

Among the mold films, the lower mold film may be formed of an oxide of any one of PE-TEOS, BPSG, USG, BSG, and SOG compositions, and the upper mold film may be an amorphous carbon film, polyaniline ether film, or photoresist film containing amorphous carbon. It can be formed as.

In addition, according to an embodiment of the present invention, after the step of sufficiently filling the opening, the step of curing at 100 to 400 ℃ is further performed. The sacrificial film may be removed using a chemical mechanical polishing process, an ashing process, or a process combining chemical mechanical polishing and ashing.

According to the cylindrical capacitor through the above process, the upper mold film to be removed together with the sacrificial film as an amorphous carbon film, a polyaniline ether film or a photoresist film that can be easily removed by an ashing process instead of the existing oxide. As a result, it is possible to prevent the interlayer insulating film made of an oxide adjacent to the contact plug from being etched by the etching knife in the wet etching process.

In addition, since the upper mold layer is removed inside the cylinder of the lower electrode when the sacrificial layer is removed, the lower mold layer remains to serve as a supporting structure, thereby enhancing the supporting force of the lower electrode, thereby preventing the lower electrode from being inclined. Occurrence can be reduced. Therefore, the defective operation of the semiconductor device can be reduced and the reliability can be improved.

Hereinafter, a cylindrical capacitor according to preferred embodiments of the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings. In the accompanying drawings, the dimensions of the substrates, layers (films), pads, patterns or structures are shown in greater detail than actual for clarity of the invention. In the present invention, each layer (film), region, pad, pattern, or structure is referred to as being formed "on", "top" or "bottom" of the substrate, each layer (film), region pad or patterns. Whereby each layer (film), region, pad, pattern or structure is formed directly over or below the substrate, each layer (film), region, pad or patterns, or another layer (film), other Regions, other pads, other patterns or other structures may additionally be formed on the substrate. Further, where each layer (film), region, pad, pattern or structure is referred to as "first", "second" and / or "third", it is not intended to limit these members but only each layer (film ), Areas, pads, patterns or structures. Thus, "first", "second" and / or "third" may be used selectively or interchangeably for each layer (film), region, pad, pattern or structures, respectively.

Cylindrical capacitors

1 is a cross-sectional view showing a cylindrical capacitor according to an embodiment of the present invention.

The cylindrical capacitor according to the present exemplary embodiment includes the lower mold layer pattern 118a made of oxide as a supporting structure of the lower electrode 122a to form the lower electrode 122a.

In detail, the cylindrical capacitor includes a lower electrode 122a having a cylindrical shape using polysilicon or metal doped on the substrate 100 having the contact region.

The lower mold layer pattern 118a made of an oxide is formed on the exposed substrate 100 because the lower electrode 122a is not formed, and the lower mold layer pattern 118a is easily removed by ashing. An upper mold film pattern (not shown) is formed. In this case, as an example of the upper mold layer pattern, an amorphous carbon layer (ACL), poly aniline ether (PAE) film or photoresist (PR; photo-resist) film including amorphous carbon, etc. Can be mentioned. In this embodiment, it is preferable to use a photoresist film. Here, the upper mold layer pattern is removed by ashing, thereby preventing an etching problem of the interlayer insulating layer due to wet etching. As a result, the support structure including the lower mold layer pattern 118a supporting the lower side of the lower electrode 122a is provided at a predetermined height.

As an example, the support structure may be formed to have a height of 0.05 to 0.3 times the height of the lower electrode 122a. In addition, as an example, the oxide forming the support structure may be formed of any one oxide of PE-TEOS, BPSG, Undoped Silicate Glass (USG), Boron Silicate Glass (SGS), and Spin On Glass (SOG) composition. .

Subsequently, a dielectric film 126 is formed on the lower electrode 122a and the support structure. Subsequently, an upper electrode 128 is provided on the dielectric layer 126.

The cylindrical capacitor having the above-described structure is provided with a support structure for supporting the side of the lower portion of the lower electrode to enhance the support force of the lower electrode to prevent the inclined sticking phenomenon between the lower electrode.

Method of manufacturing a cylindrical capacitor

2 to 8 are cross-sectional views illustrating a method of manufacturing the cylindrical capacitor shown in FIG. 1.

Referring to FIG. 2, a shallow trench isolation (STI) process is performed on a substrate 100 to form an isolation layer 102 for isolation between devices. A transistor including a source / drain 106 and a gate 104 is formed on the substrate 100 on which the device isolation layer 102 is formed. Next, a first interlayer insulating film 109 made of an oxide filling the transistor is formed.

The first interlayer insulating layer 109 is partially etched to form first and second pad electrodes 108a and 108b exposing the source / drain 106. Through a subsequent process, the first pad electrode 108a is connected with the bit line, and the second pad electrode 108b is connected with the capacitor.

The bit line 110 connected to the first pad electrode 108a is formed on the first interlayer insulating layer 109. Next, a second interlayer insulating film 112 made of an oxide filling the bit line 110 is formed.

The second interlayer insulating layer 112 is partially etched by a photolithography process to form a contact hole exposing the second pad electrode 108b.

Next, by filling a conductive material consisting of a doped polysilicon or metal inside the contact hole and etching the conductive material until the second interlayer insulating film 112 is exposed using a chemical mechanical polishing or etch back process And a contact plug 114 for connecting with the lower electrode of the capacitor.

Subsequently, an etch stop layer 115 is formed on the second interlayer insulating layer 112 on which the contact plug 114 is formed. The etch stop layer 115 is formed as a material having an etch selectivity with a mold layer 117 formed subsequently. In other words, the etch stop layer 115 should be formed of a material that is hardly etched under etching conditions for etching the mold layer 117. In detail, the etch stop layer 115 may be formed of a silicon nitride layer.

Referring to FIG. 3, a mold layer 117 including a lower mold layer 117a and an upper mold layer 117b is formed on the substrate 100.

In detail, the lower mold layer 117a formed of an oxide is formed on the etch stop layer 115 of the substrate 100, and the lower mold layer 117a is easily removed by ashing on the lower mold layer 117a. The upper mold film 117b is formed.

An example of the lower mold layer 117a may be formed using an oxide film of a PE-TEOS, BPSG, USG, BSG, or SOG composition. In addition, examples of the upper mold layer 117b include an amorphous carbon film (ACL), a polyaniline ether (PAE) film, a photoresist (PR) film, and the like containing amorphous carbon. In this embodiment, it is preferable to use a photoresist film.

As an example, the amorphous carbon film may be formed by coating through Chemical Vapor Deposition (CVD) at a temperature of about 550 ° C. The polyaniline ether film may be formed on the lower mold layer 117a to be dense by hard baking at about 400 ° C. In addition, the photoresist film may be formed by providing a photoresist on the substrate 100 and then coating the photoresist on the substrate 100 by a spin coating method, followed by baking.

In addition, for example, by forming the mold layer 117 by stacking two or more layers having different etch rates among the materials, the shape of the sidewall of the lower electrode of the capacitor formed in a subsequent process may be changed.

The thickness of the mold layer 117 can be appropriately adjusted according to the capacitance required for the capacitor. That is, since the height of the capacitor is mainly determined by the thickness of the mold film 117, the thickness of the mold film 117 can be appropriately adjusted according to the required capacitance. Here, the lower mold layer 117a is not removed as a support structure for supporting the lower electrode when the subsequent lower electrode is formed, and is left by a predetermined height of the lower electrode. In particular, the support structure is formed to have a height of 0.05 to 0.3 times the height of the lower electrode to fix the lower electrode so as not to tilt.

Subsequently, the upper mold layer 117 may be formed by flattening the upper mold layer 117b by a chemical mechanical polishing process.

Referring to FIG. 4, a mold layer pattern 118 having an opening 120 exposing the substrate 100 is formed.

In detail, the photoresist pattern 119 is formed on the mold layer 117, and then the mold layer 117 and the etch stop layer 115 are sequentially patterned. As a result, the mold layer pattern 118 and the etch stop layer pattern 116 having the opening 120 exposing the top surface of the contact plug 114 are formed. In this case, the mold layer pattern 118 includes a lower mold layer pattern 118a and an upper mold layer pattern 118b. The etch stop layer pattern 116 may be excessively etched so that the etch stop layer pattern 116 does not remain on the bottom surface of the opening 120 on the substrate 100.

Subsequently, the photoresist pattern 119 is removed by an ashing and cleaning process.

Referring to FIG. 5, the conductive film 122 for lower electrodes is continuously formed on the sidewalls and the bottom surface of the opening 120 and the upper surface of the mold layer pattern 118. For example, the lower electrode conductive layer 122 may be formed of a conductive material including a doped polysilicon or a metal such as tungsten (W), titanium (Ti), titanium nitride (TiN), or tungsten nitride (WiN). Can be. In this case, the conductive materials may be used alone or in combination.

Referring to FIG. 6, a sacrificial film 124 made of a photoresist for sufficiently filling the opening 120 is formed on the resultant having the lower electrode conductive film 122. Specifically, the sacrificial layer 124 covering the opening 120 on the resultant having the lower electrode conductive layer 122 is formed by spin coating a photoresist.

Subsequently, the substrate on which the sacrificial film 124 is formed is heat treated at 100 to 400 ° C. As a result, polymers included in the photoresist are cross-linked to form a cured sacrificial layer 124.

Referring to FIG. 7, the sacrificial layer 124 and the lower electrode conductive layer 122 are etched until the surface of the mold layer pattern 118 is exposed, and the sacrificial layer pattern 124a remains inside. The electrode 122a is formed.

In detail, the upper surface of the mold layer pattern 118 is formed by chemical mechanical polishing of the sacrificial layer 124 and the lower electrode conductive layer 122 exposed on the upper surface of the mold layer pattern 118. The planarization process is performed until exposed. As a result, the lower electrode 122a is formed on the inner wall of the opening 120, the cylindrical conductive film pattern 122a remains, and the sacrificial film pattern 124a exists therein.

In the present invention, the conductive film pattern 122a may be formed by a chemical mechanical polishing process, an etch back process, or a combination thereof.

In this case, the slurry used for the chemical mechanical polishing process has an etching selectivity such that the removal rate between the photoresist and the conductive material is 10: 1 or less. As an example, a conventional oxide slurry containing ceria (CeO ₂ ) or silica (SiO ₂ ) as an abrasive may be used. The soft pad in the present invention uses a polytex pad or a Suva series.

For example, the slurry includes about 0.5 to about 10.0 wt% of the abrasive particles, and the abrasive particles include alumina (Al ₂ O ₃ ), titania (TiO ₂ ), zirconia (ZrO ₂ ), germania (GeO ₂ ), ceria (CeO ₂ ), silica (SiO ₂ ) may be included.

After the process is performed using the slurry having such a composition, the sacrificial film pattern 124a remains inside the cylinder of the lower electrode 122a, and the mold film pattern is formed outside the cylinder of the lower electrode 122a. 118) remains.

For example, after the planarization process, a cleaning process for removing the etching material and the etching residue remaining in the mold layer pattern 118 and the conductive layer pattern 122a may be further performed.

Referring to FIG. 8, the lower electrode 122a and the lower electrode 122a are exposed on the substrate 100 by removing the sacrificial layer pattern 124a and the upper mold layer 118b of the mold layer pattern 118. A support structure 118a supporting the lower side of

Specifically, the sacrificial layer pattern 124a is removed to expose sidewalls of the lower electrode 122a. At the same time, only the upper mold layer pattern 118b of the mold layer pattern 118 is removed to form a support structure for supporting the lower side surface of the lower electrode 122a. At this time, the sacrificial film pattern 124a remaining in the opening 120 and the upper mold film pattern 118b are simultaneously removed by an ashing process using an oxygen plasma. This is because the photoresist constituting the sacrificial film pattern 124a and the amorphous carbon film, polyaniline ether film, or photoresist film constituting the upper mold layer pattern 118b are easily removed by ashing. As a result, the lower electrode 112a having the lower mold film pattern 118a not removed by the ashing process as a support structure on the side is completed.

In the conventional removal of the upper mold layer pattern 118b, since the mold layer 118 is mostly made of only an oxide, an etchant including hydrogen fluoride (HF), an ammonium hydroxide, hydrogen peroxide and deionized water Or it was removed by a wet etching process using an etchant such as LAL etchant containing ammonium fluoride, hydrogen fluoride, distilled water and the like. In the wet etching process, an etch radical penetrates into the gap 130 between the lower electrode 122a and the etch stop layer pattern 116 during the process, thereby removing the interlayer insulating layer 112 formed of an oxide adjacent to the contact plug 114. There was a drawback to etching. In addition, the etching solution may cause a surface tension on the surface of the lower electrode 122a, causing the slanted adhesion.

However, according to the present invention, the upper mold layer 118b may be formed of an amorphous carbon film, a polyaniline ether film, or a photoresist film, which may be easily removed by an ashing process, thereby preventing a problem due to penetration of an etching chemical. .

In addition, the lower mold layer 118a is provided as a support structure outside the cylinder of the lower electrode 112a to strengthen the supporting force of the lower electrode 112a, thereby preventing the inclination between the lower electrodes 112a. Can be.

 Subsequently, the dielectric capacitor 126 and the upper electrode 128 are sequentially formed on the surface of the lower electrode 122a to complete the cylindrical capacitor shown in FIG. 1.

Specifically, the dielectric layer 126 includes an oxide-nitride, an oxide-nitride-oxide, a metal oxide, or the like. However, recently, there has been a tendency to select the metal oxide having good leakage current characteristics while sufficiently lowering the equivalent oxide film thickness, and to perform atomic layer deposition to form the dielectric film 126. In particular, the atomic layer deposition for forming the dielectric film 126 is repeated at least once in the order of supply of the reaction material → purge → supply of the oxidant → purge. Then, a dielectric film 126 of metal oxide is formed on the surface of the lower electrode 122a.

Like the lower electrode 122a, the upper electrode 128 mainly includes polysilicon, metal, metal nitride, and the like. Recently, metal nitrides, which are more advantageous in terms of integration degree, are mainly selected as the upper electrode 128.

As described above, a capacitor is formed on the substrate 100 by sequentially forming the dielectric film 126 and the upper electrode 128 on the lower electrode 122a. Since the capacitor formed through the above process includes the cylindrical lower electrode 122a, the storage capacity can be sufficiently secured, and the inferior defect of the lower electrode 122a can be reduced, so that the reliability of the semiconductor device can be improved.

As described above, according to the present invention, an amorphous carbon film, a polyaniline ether film or a photoresist that can be easily removed by an ashing process in place of an existing oxide of the upper mold film pattern removed together with the sacrificial film pattern is provided. By forming a film having a film, the loss of the interlayer insulating film adjacent to the contact plug can be prevented by etching radicals in the wet etching process.

In addition, it is possible to reduce the occurrence of the inclined sticking phenomenon of the lower electrode by leaving the lower mold layer, which removes the lower mold layer, which enhances the supporting force of the lower electrode. Therefore, the defective operation of the semiconductor device can be reduced and the reliability can be improved.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (7)

A lower electrode formed on the substrate; A support structure formed on a substrate having the lower electrode and supporting a side surface of the lower electrode; A dielectric film continuously formed on the lower electrode and the support structure; And And a cylindrical capacitor formed on the dielectric layer. The cylindrical capacitor of claim 1, wherein the support structure has a height of 0.05 to 0.3 times the height of the lower electrode. Forming a mold film including a lower mold film and an upper mold film on a substrate; Forming a mold film pattern having an opening exposing the substrate; Continuously forming a conductive film for the lower electrode on the sidewalls and the bottom surface of the opening and the upper surface of the mold layer pattern; Filling the opening sufficiently by forming a sacrificial film made of photoresist on the resultant having the conductive film for the lower electrode; Etching the sacrificial layer and the lower electrode conductive layer on the mold layer pattern until the surface of the mold layer pattern is exposed to form a lower electrode having a sacrificial layer pattern left therein; Forming a lower electrode exposed on the substrate and a support structure for supporting a lower side of the lower electrode by removing the sacrificial layer pattern and the upper mold layer of the mold layer pattern; Forming a dielectric film having a substantially uniform thickness on the lower electrode and the support structure; And And forming an upper electrode on the dielectric layer. The method of claim 3, wherein the lower mold layer is an oxide of any one of PE-TEOS, BPSG, USG, BSG, and SOG compositions. 4. The method of claim 3, wherein the upper mold layer includes amorphous carbon, polyaniline ether or photoresist. The method of claim 3, wherein the sacrificial film is removed using a chemical mechanical polishing process, an ashing process, or a combination of chemical mechanical polishing and ashing. The method of manufacturing a cylindrical capacitor according to claim 3, further comprising curing at 100 to 400 ° C. after the step of sufficiently filling the opening.

Images