KR20090122560A - Capacitor and method for fabricating the same - Google Patents

Abstract

PURPOSE: A capacitor and a method for manufacturing the same are provided to prevent the collapse and breakage of a storage node by forming a storage with the bottom thicker than the side. CONSTITUTION: In a capacitor and a method for manufacturing the same, a cylindrical storage node is formed on a substrate(11), and the thickness of the bottom is thicker than the sidewall. The cylindrical storage node comprises a first conductive film(18A) forming the sidewall and a second conductive film(19) forming the bottom. The first conductive film comprises silicon or metal, and the second conductive film comprises silicon. A sacrificing layer(15A) having an open part exposing a part of substrate to the outside is formed on the substrate. The second conductive film is formed through a selective epitaxial growth process.

Description

Capacitor and Method for Manufacturing the Same {CAPACITOR AND METHOD FOR FABRICATING THE SAME}

TECHNICAL FIELD The present invention relates to semiconductor manufacturing technology, and more particularly, to a capacitor and a method of manufacturing the same.

The area occupied by capacitors is decreasing with increasing integration, miniaturization, and speed of semiconductor devices. Although the semiconductor device is highly integrated and miniaturized, the capacitance of the capacitor for driving the semiconductor device should be at least secured. Recently, as the size of a semiconductor device is reduced to an ultra-small sized device, the height of the capacitor is increasing to secure the capacity of the capacitor in the development process of the semiconductor device.

In addition, to secure the capacity of the capacitor, a cylindrical storage node that can use both inside and outside instead of a concave type is applied. When the cylindrical storage node is applied, it is advantageous to secure the capacitance in the storage node even in the ultrafine devices.

However, in the case of the storage node, the area is reduced and the aspect ratio is increased due to the high integration and miniaturization of the semiconductor device, and the falling or breaking phenomenon is caused by tension due to wet cleaning in the deep-out process for forming the cylindrical storage node. There is a problem that occurs. In addition, the collapsed or broken storage nodes have a problem of forming a bridge with other storage nodes formed around or contacting the normally formed storage nodes.

1 is a top view photograph illustrating a problem of a storage node according to the related art.

Referring to FIG. 1, it can be seen that storage nodes are collapsed or broken to form bridges with other storage nodes or are in contact with normally formed storage nodes.

The present invention has been proposed to solve the above problems of the prior art, and an object thereof is to provide a capacitor and a method of manufacturing the same, which can prevent a failure of a cylindrical storage node.

Capacitor according to an embodiment of the present invention for achieving the above object is characterized in that it comprises a cylindrical storage node formed on the substrate and the thickness of the bottom portion is thicker than the thickness of the side wall.

In particular, the cylindrical storage node may include a first conductive layer forming a sidewall and a second conductive layer forming a bottom portion.

In addition, the first conductive film is characterized in that it comprises silicon or metal.

In addition, the second conductive film is characterized in that it comprises silicon.

A method of manufacturing a capacitor according to an embodiment of the present invention for achieving the above object is characterized in that it comprises the step of forming a storage node thicker than the thickness of the side wall thickness of the bottom portion on the substrate.

In particular, the forming of the storage node may include forming a sacrificial layer having an open portion exposing a portion of the substrate on a substrate; Forming a first conductive film along a step on the entire structure including the open part; Leaving the first conductive film on the sidewall of the open portion; Forming a second conductive film thicker than a thickness of the first conductive film on a lower substrate of the open part; Removing the sacrificial film.

In addition, the first conductive film is characterized in that it comprises silicon or metal series.

In addition, the second conductive film is characterized in that it comprises silicon.

In addition, the second conductive film is formed by a selective epitaxial growth process.

In addition, the second conductive film is formed using a mixed gas of PH ₃ , SiH ₂ Cl _2, and HCl by applying a pressure of 90 mTorr to 150 mTorr at a temperature of 700 ° C. to 950 ° C.

In addition, the second conductive film is formed using a mixed gas of PH ₃ , SiH _4, and H ₂ by applying a pressure of 120 mTorr to 200 mTorr at a temperature of 550 ° C. to 700 ° C.

The method may further include removing impurities before forming the second conductive film.

The removing of the impurities may be performed by dry etching.

In addition, the dry etching is characterized in that to proceed using a mixed gas of N ₂ and H ₂ .

In addition, the step of leaving the first conductive film on the side wall of the open portion, characterized in that the dry etching proceeds.

The dry etching may be performed by applying a bottom power of 50 kW to 600 kW.

The above-described capacitor and a method of manufacturing the same according to the present invention form a storage node whose bottom portion is thicker than the thickness of the sidewall, thereby preventing the storage node from falling or breaking due to tension in the deep-out process for forming the cylindrical storage node. It can work. Therefore, there is an effect that can prevent the bridge and the like with other storage nodes.

In addition, it is possible to prevent the penetration of the etching solution to the lower portion during the dip-out process, it is possible to prevent the loss of the storage node contact plug and interlayer insulating film.

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

The present invention is to form a storage node thicker than the thickness of the side wall to prevent the storage node from falling or breaking due to tension in the deep-out process for forming a cylindrical storage node, as shown in FIG. This will be described in detail.

2 is a cross-sectional view illustrating a capacitor according to an embodiment of the present invention.

As shown in FIG. 2, an insulating film 12 is formed on the substrate 11, and a storage node contact plug 13 is formed through the insulating film 12 and connected to the substrate 11. An etch stop layer 14 is formed on the insulating layer 12 to open the storage node contact plug 13. A cylindrical storage node SN is formed on the storage node contact plug 13 in which the bottom portion has a thickness greater than that of the side wall.

In particular, the cylindrical storage node SN includes a first conductive layer 18A forming sidewalls and a second conductive layer 19 forming a bottom portion. The first conductive layer 18A may include silicon or metal, and the second conductive layer 19 may include silicon. After the first conductive film 18A is formed, the second conductive film 19 thicker than the thickness of the first conductive film 18A is formed to perform wet cleaning in the dip-out process for forming the cylindrical storage node SN. It is possible to prevent the collapse or breakage caused by the tension caused by. In addition, the wet solution is prevented from penetrating into the lower insulating film 12 and the storage node contact plug 13 in the dip-out process, thereby preventing the loss of the storage node contact plug 13 and the loss of the insulating film 12 by the wet solution. You can prevent it.

3A to 3F are cross-sectional views illustrating a method of manufacturing a capacitor according to an embodiment of the present invention. For convenience of description, the same reference numerals as in FIG. 2 will be used.

As shown in FIG. 3A, an insulating film 12 is formed on the substrate 11. The substrate 11 may be a semiconductor (silicon) substrate on which a DRAM process is performed. In addition, the substrate 11 may be a substrate on which predetermined processes such as an isolation layer and a gate pattern are completed. In addition, the bit line pattern may be formed on the substrate 11 before the insulating layer 12 is formed.

The insulating layer 12 is for interlayer insulation between the substrate 11 and the upper layer, and may include an oxide layer. The oxide film is HDP (High Density Plasma) oxide film, BPSG (Boron Phosphorus Silicate Glass) film, PSG (Phosphorus Silicate Glass) film, BSG (Boron Silicate Glass) film, TEOS (Tetra Ethyle Ortho Silicate) film, USG (Un-doped Silicate) film Glass (FSG), Fluorinated Silicate Glass (FSG) film, Carbon Doped Oxide (CDO) film, and Organic Silicate Glass (OSG) film, or any one selected from the group consisting of a laminated film of at least two or more layers can be formed have. Alternatively, the film may be formed by a spin coating method such as a spin on dielectric (SOD) film.

Subsequently, a storage node contact plug 13 penetrates the insulating layer 12 and is connected to the substrate 11. To this end, a mask pattern is formed on the insulating film 12, the insulating film 12 is etched to form a contact hole so that the substrate 11 is opened with the mask pattern as an etch barrier, and then a contact hole is formed. The material may be buried and the planarization process may proceed. The planarization process may proceed to the target on which the surface of the insulating film 12 is exposed. In addition, the planarization process may be performed by an etch back or a CMP process, but is preferably performed by a CMP process having excellent planarization characteristics. Metal polishing slurries may be used in the CMP process.

The conductive material for forming the storage node contact plug 13 may be formed of any one selected from the group consisting of a transition metal film, a rare earth metal film, an alloy film thereof, or a silicide film thereof. Further, it may be formed of a polysilicon film doped with impurity ions. In addition, the conductive materials may be formed in a laminated structure in which at least two layers are stacked.

Subsequently, an etch stop layer 14 is formed on the insulating layer 12 including the storage node contact plug 13. The etch stop layer 14 is to prevent the insulating layer 12 from being lost when forming an opening for a subsequent storage node. The etch stop layer 14 uses a material having a selectivity different from that of the subsequent sacrificial layer and the insulating layer 12. The etch stop layer 14 may be formed of a nitride layer.

Subsequently, a sacrificial layer 15 is formed on the etch stop layer 14. The sacrificial layer 15 is to provide an open portion for forming a subsequent storage node, and may be formed high to secure the capacitance of the capacitor, and may be formed in a single layer or multiple layers. When the sacrificial layer 15 is formed in multiple layers, it is possible to prevent the line width reduction and the contact open failure of subsequent openings by using the selectivity between the layers.

The sacrificial layer 15 may be formed of the same material as the insulating layer 12. The sacrificial layer 15 may include an oxide layer. The oxide film is HDP (High Density Plasma) oxide film, BPSG (Boron Phosphorus Silicate Glass) film, PSG (Phosphorus Silicate Glass) film, BSG (Boron Silicate Glass) film, TEOS (Tetra Ethyle Ortho Silicate) film, USG (Un-doped Silicate) film Glass (FSG), Fluorinated Silicate Glass (FSG) film, Carbon Doped Oxide (CDO) film, and Organic Silicate Glass (OSG) film, or any one selected from the group consisting of a laminated film of at least two or more layers can be formed have. Alternatively, the film may be formed by a spin coating method such as a spin on dielectric (SOD) film.

Subsequently, a mask pattern 16 is formed on the sacrificial layer 15. The mask pattern 16 may be formed such that at least an upper portion of the storage node contact plug 13 is opened. To this end, the photoresist may be coated on the sacrificial layer 15 and patterned by exposure and development to open the upper portion of the storage node contact plug 13. In addition, a hard mask may be further formed before the photoresist layer is formed to secure an etching margin.

As shown in FIG. 3B, the sacrificial layer 15 and the etch stop layer 14 are etched using the mask pattern 16 as an etch barrier to form an open portion 17 exposing the storage node contact plug 13. .

Since the selectivity of the sacrificial layer 15 and the etch stop layer 14 are different from each other, the sacrificial layer 15 and the etch stop layer 14 may be divided into etching the sacrificial layer 15 and etching the etch stop layer 14. That is, when the sacrificial film 15 is an oxide film, the etching is performed using a gas for etching the oxide film, and when the etching stop film 14 is a nitride film, the etching is performed using a gas for etching the nitride film. In this case, since the etch stop layer 14 is not etched when the sacrificial layer 15 is etched, loss of the lower insulating layer 12 may be prevented.

As shown in FIG. 3C, the mask pattern 16 is removed. When the mask pattern 16 is a photoresist layer, the mask pattern 16 may be removed by dry etching. Dry etching can be carried out by an oxygen strip process. After the mask pattern 16 is removed, the cleaning process may be performed.

Next, the first conductive film 18 is formed along the step on the entire structure including the open portion 17. The first conductive layer 18 serves as a storage node together with the subsequent second conductive layer, and may include silicon or metal. In this case, the metal may include a laminated structure of titanium and a titanium nitride film.

As shown in FIG. 3D, the first conductive film 18A is left on the sidewall of the open portion 17. To this end, the first conductive layer 18 (see FIG. 3C) formed on the sacrificial layer 15 and the first conductive layer 18 formed on the bottom of the open part 17 are selectively etched. Etching of the first conductive film 18 may be performed by dry etching. In particular, an etching using straight ions may be used to leave the first conductive film 18A on the sidewall of the open portion 17. For this purpose, etching may be performed by applying a bottom power of 50 kW to 600 kW.

Accordingly, the first conductive film 18 formed on the top of the sacrificial film 15 and the bottom of the open part 17 is removed, and the first conductive film 18A remains only on the sidewall of the open part 17.

As shown in FIG. 3E, the second conductive layer 19 thicker than the thickness of the first conductive layer 18A is formed on the bottom of the open portion 17, that is, the storage node contact plug 13.

Before the second conductive layer 19 is formed, impurities on the storage node contact plug 13 are removed. To this end, dry etching may be performed, and dry etching may be performed using a mixed gas of N ₂ and H ₂ .

The second conductive film 19 may include silicon. In addition, the second conductive layer 19 may be formed by a selective epitaxial growth process. Since impurities on the storage node contact plug 13 are removed by dry etching before the second conductive layer 19 is formed, the growth of silicon is not prevented by the impurities.

The second conductive film 19 formed by the selective epitaxial growth process may be formed using a mixed gas of PH ₃ , SiH ₂ Cl _2, and HCl by applying a pressure of 90 mTorr to 150 mTorr at a temperature of 700 ° C. to 950 ° C. Can be. The second conductive film 19 may be formed using a mixed gas of PH ₃ , SiH _4, and H ₂ by applying a pressure of 120 mTorr to 200 mTorr at a temperature of 550 ° C. to 700 ° C. FIG.

As described above, by forming the second conductive film 19 thicker than the thickness of the first conductive film 18A at the bottom of the open portion 17, the storage node SN whose bottom portion is thicker than the sidewall thickness is formed. Form. The storage node SN includes a first conductive layer 18A forming sidewalls and a second conductive layer 19 forming a bottom portion. By forming the storage node SN thicker than the thickness of the side wall, it is possible to strengthen the reinforcement and lower support of the contact area to prevent deformation of the capacitor by external force. That is, in the deep-out process for forming the subsequent cylindrical storage node, it is possible to prevent the collapse or breakage from occurring due to the tension caused by the wet etching solution.

As shown in FIG. 3F, a dip out process is performed to form a cylindrical storage node SN. In FIG. 3E, by forming the storage node SN to have a thickness greater than that of the side wall, the storage node SN may be prevented from falling or breaking due to the tension caused by the wet etching solution in the deep-out process. Therefore, it is possible to form a bridge with another neighboring storage node or to prevent contact with a normally formed storage node. In addition, the etching solution may be prevented from penetrating into the lower portion of the storage node SN during the dip-out process, thereby preventing the loss of the storage node contact plug 13 and the loss of the insulating layer 12 due to the etching solution.

In a subsequent process, a dielectric layer and a plate node may be formed on the storage node SN to form a cylindrical capacitor.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

1 is a top view photograph for explaining a problem of a storage node according to the prior art;

2 is a cross-sectional view illustrating a capacitor according to an embodiment of the present invention;

3A to 3F 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 substrate 12 insulating film

13: storage node contact plug 14: etch stop

15: sacrificial film 16: mask pattern

17: open portion 18: the first conductive film

19: second conductive film

SN: Storage Node

Claims (16)

Cylindrical storage nodes formed on the substrate and whose thickness at the bottom is thicker than the thickness of the sidewalls Capacitor comprising a. The method of claim 1, The cylindrical storage node includes a first conductive film forming a side wall and a second conductive film forming a bottom portion. The method of claim 1, The first conductive film is a capacitor containing silicon or metal. The method of claim 1, The second conductive film is a capacitor containing silicon. Forming a storage node on the substrate, wherein the bottom portion is thicker than the sidewall thickness Method of manufacturing a capacitor comprising a. The method of claim 5, Forming the storage node, Forming a sacrificial layer having an open portion exposing a portion of the substrate on the substrate; Forming a first conductive film along a step on the entire structure including the open part; Leaving the first conductive film on sidewalls of the open portion; Forming a second conductive film thicker than a thickness of the first conductive film on a lower substrate of the open part; Removing the sacrificial layer Method of manufacturing a capacitor comprising a. The method of claim 6, The first conductive film is a capacitor manufacturing method comprising a silicon or metal series. The method of claim 6, The second conductive film is a manufacturing method of a capacitor containing silicon. The method of claim 8, The second conductive film is a method of manufacturing a capacitor formed by a selective epitaxial growth (Selective Epitaxial Growth) process. The method of claim 9, The second conductive film is applied to a pressure of 90mTorr ~ 150mTorr at a temperature of 700 ℃ to 950 ℃, a method of producing a capacitor using a mixed gas of PH ₃ , SiH ₂ Cl ₂ and HCl. The method of claim 9, The second conductive film is applied to a pressure of 120mTorr to 200mTorr at a temperature of 550 ℃ to 700 ℃, a method of manufacturing a capacitor formed using a mixed gas of PH ₃ , SiH ₄ and H ₂ . The method of claim 6, Before forming the second conductive film, Capacitor manufacturing method further comprising the step of removing impurities. The method of claim 12, Removing the impurities, Method of manufacturing a capacitor to proceed by dry etching. The method of claim 13, The dry etching is a method of manufacturing a capacitor to proceed using a mixture of N ₂ and H ₂ gas. The method of claim 6, Residually leaving the first conductive film on the side wall of the open portion, Method of manufacturing a capacitor to proceed by dry etching. The method of claim 15, The dry etching is a method of manufacturing a capacitor to proceed by applying a bottom power of 50 ~ 600Ｗ.

Images