KR20060000921A - Capacitor in semiconductor device and method for fabricating the same - Google Patents

Abstract

The present invention is to provide a three-dimensional cylindrical capacitor and a method for manufacturing the lower electrode is more durable than the conventional, by increasing the area that the lower electrode is in contact with the lower layer, for this purpose, the present invention stops the etching on the substrate is completed Forming a film; Forming an insulating film for forming a capacitor on the etch stop film; Selectively removing the capacitor forming insulating layer in the region where the capacitor is to be formed, to form a capacitor forming hole exposing the etch stop film; Removing a portion of an etch stop layer formed at a lower portion of the capacitor forming insulating layer, which is a peripheral area of the bottom of the capacitor forming hole, to form a gap for forming a lower electrode; Forming a conductive film on an inner surface of the capacitor forming hole, and allowing the conductive film to be filled in the gap for forming the lower electrode, thereby forming a lower electrode having an annular border on an outer wall; Removing the capacitor forming insulating film; Forming a dielectric thin film on a surface of the lower electrode; And forming an upper electrode on the dielectric thin film.

Semiconductors, capacitors, cylinders, lower electrodes, etch stops.

Description

CAPACITY OF SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD THEREOF {CAPACITOR IN SEMICONDUCTOR DEVICE AND METHOD FOR FABRICATING THE SAME}             

1A to 1C are views showing a three-dimensional cylindrical capacitor manufacturing method of a semiconductor device according to the prior art.

1D is a diagram showing a problem when manufacturing a three-dimensional cylindrical capacitor according to the prior art.

Figure 2 is an electron micrograph showing the problem of Figure 1d.

3A to 3E illustrate a method of manufacturing a three-dimensional cylindrical capacitor in a semiconductor device according to a preferred embodiment of the present invention.

Explanation of symbols on main parts of drawing

34 etch stop film

35: insulating film for forming the capacitor lower electrode

36: hole for forming the capacitor lower electrode

38: lower electrode

39: dielectric thin film                 

40: upper electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly, to a capacitor of a semiconductor device having a three-dimensional cylinder structure and a manufacturing method thereof.

As the degree of integration of semiconductor memory devices, in particular DRAM (Dynamic Random Access Memory), increases, the area of memory cells, which are basic units for information storage, has been rapidly reduced.

Such a reduction in the memory cell area is accompanied by a reduction in the area of the cell capacitor, thereby lowering the sensing margin and the sensing speed, and causes a problem that the durability against soft errors caused by α-particles is degraded. Accordingly, there is a need for a method capable of securing sufficient capacitance in a limited cell area.

The capacitance C of the capacitor is defined as in Equation 1 below.

C = εAs / d

Is the dielectric constant, As is the effective surface area of the electrode, and d is the distance between the electrodes. Therefore, in order to increase the capacitance of the capacitor, it is necessary to increase the surface area of the electrode, reduce the thickness of the dielectric thin film, or increase the dielectric constant.                         

Among them, a method of increasing the effective surface area of the electrode in a limited layout area by first making a three-dimensional form of the electrode structure of the capacitor, such as a concave structure and a cylinder structure, was first considered.

The concave structure forms a hole in which an electrode of a capacitor is to be formed in an insulating film, a lower electrode of a capacitor is formed on an inner surface of the hole, and a dielectric thin film and an upper electrode are formed thereon. However, as semiconductor memory devices are increasingly integrated, it is difficult to secure sufficient capacitor capacity per cell within a limited cell area even with a concave structure, and thus a cylinder structure capable of providing a larger surface area has been proposed.

The cylinder structure forms a hole in which the electrode of the capacitor is to be formed in the insulating film, forms a lower electrode of the capacitor in the hole, removes the insulating film used as a formwork, and then removes the dielectric thin film and the upper electrode along the remaining lower electrode surface. It is a form laminated in order.

Therefore, the cylinder structure can use both the inner and outer surfaces of the lower electrode as the effective surface area of the capacitor, thereby forming a capacitor having a larger capacitance in a limited area than the concave structure.

However, the degree of integration of semiconductor memory devices is increasing and the area allocated to one unit cell continues to decrease. On the other hand, in a situation where a capacitor needs a constant capacity to maintain stable data, the shape of electrodes in which a capacitor of a cylinder structure is also manufactured is getting narrower in width and higher in height.

When the shape of the capacitor lower electrode of the cylindrical structure decreases in the horizontal direction and increases only in the vertical direction, the supporting force of the lower electrode decreases, resulting in frequent damaging between the lower electrodes after the removal of the capacitor oxide film. As a result, a problem occurs that causes a device failure by causing a bridge or the like.

1A to 1C are views showing a three-dimensional cylindrical capacitor manufacturing method of a semiconductor device according to the prior art.

First, as shown in FIG. 1A, the interlayer insulating film 12 is formed on the semiconductor substrate 10 on which the active region 11 is formed, and then penetrates the interlayer insulating film 12 to form an active region ( A contact hole connected to 11) is formed. A contact plug 13 is formed by filling the contact hole with a conductive material.

Subsequently, the etch stop film 14 is formed using a silicon nitride film or the like, and the insulating film 15 for forming the capacitor lower electrode is formed so that the lower electrode of the capacitor is formed thereon.

Subsequently, the insulating film 15 in the region where the capacitor is to be formed is selectively removed to form the capacitor lower electrode forming hole 16. At this time, the etch stop layer 14 prevents the contact plug 13, which is a lower structure, from being etched. The insulating film 15 for forming the capacitor lower electrode serves as a form for forming the lower electrode of the capacitor.

Subsequently, as shown in FIG. 1B, the lower electrode 17 is formed of a conductor film along the inner surface of the capacitor lower electrode forming hole 16.

Subsequently, as shown in FIG. 1C, the insulating film 15 for forming the capacitor lower electrode is removed. Subsequently, a dielectric thin film 18 is formed along the surface of the lower electrode 17, and an upper electrode 19 is formed as a conductor film thereon.

1D is a diagram showing a problem in manufacturing a three-dimensional cylindrical capacitor according to the prior art.

Subsequently, referring to FIG. 1D, a problem in manufacturing a cylindrical capacitor according to the prior art will be described. As described above, as the memory device is highly integrated, the width of the lower electrode becomes narrower and the height becomes higher. Therefore, after removing the insulating film 15 for forming the capacitor lower electrode, the remaining lower electrode is inclined and sticks to the neighboring lower electrode.

In order to secure the capacity of a certain capacitor in a limited area, the lower electrode of the capacitor must be formed above a certain height, so the height of the lower electrode of the cylindrical capacitor cannot be lowered.

FIG. 2 is an electron micrograph showing the problem of FIG. 1D, showing a bridge phenomenon in which lower electrodes of a cylindrical capacitor stick together.

Referring to FIG. 2, it can be seen that the capacitor lower electrodes of the region B adhere to each other. If the process continues in this state, the memory device eventually becomes defective.

The present invention has been proposed to solve the above problems, and an object of the present invention is to provide a three-dimensional cylindrical capacitor having a lower electrode that is stronger than the conventional one, and a method of manufacturing the same, by increasing the area where the lower electrode contacts the lower layer.

In order to solve the above problems, the present invention comprises the steps of forming an etch stop film on the substrate is completed a predetermined process; Forming an insulating film for forming a capacitor on the etch stop film; Selectively removing the capacitor forming insulating layer in the region where the capacitor is to be formed, to form a capacitor forming hole exposing the etch stop film; Removing a portion of an etch stop layer formed at a lower portion of the capacitor forming insulating layer, which is a peripheral area of the bottom of the capacitor forming hole, to form a gap for forming a lower electrode; Forming a conductive film on an inner surface of the capacitor forming hole, and allowing the conductive film to be filled in the gap for forming the lower electrode, thereby forming a lower electrode having an annular border on an outer wall; Removing the capacitor forming insulating film; Forming a dielectric thin film on a surface of the lower electrode; And forming an upper electrode on the dielectric thin film.

In addition, the present invention is an insulating film on a substrate; A lower electrode of a cylindrical shape embedded in the insulating film up to an annular edge bonded to the bottom of the outer wall; A dielectric thin film formed on the surface of the lower electrode; And a capacitor of the semiconductor device including an upper electrode on the dielectric thin film.

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

3A to 3E are views illustrating a method of manufacturing a cylindrical capacitor according to a preferred embodiment of the present invention.

As shown in FIG. 3A, the cylindrical capacitor manufacturing method according to the present embodiment forms an interlayer insulating film 32 on the semiconductor substrate 30 on which the active region 31 is formed, and then penetrates the interlayer insulating film 32. As a result, a contact hole connected to the active region 31 of the semiconductor substrate 30 is formed. A contact plug 33 is formed by filling the contact hole with a conductive material. The interlayer insulating layer 32 may include an undoped-silicate glass (USG) film, a phospho-silicate glass (PSG) film, a boro-phospho-silicate glass (BPSG) film, a high density plasma (HDP) oxide film, and a spin on glass (SOG) film. A film, a TEOS (Tetra Ethyl Ortho Silicate) film or an oxide film using HDP (high densigy plasma), or a thermal oxide film (Thermal Oxide), which is formed by oxidizing a silicon substrate at a high temperature between 600 and 1,100 ° C in a furnace. I use it.

Subsequently, an etch stop film 34 is formed using a silicon nitride film or the like, and an insulating film 35 for forming a capacitor lower electrode is formed so that a lower electrode of the capacitor is formed thereon. Here, the etch stop film 34 is formed in the range of 500 ~ 5000Å using a silicon nitride film. Here, preferably, the insulating film 35 for forming the capacitor lower electrode is formed in the range of 5000 to 50000 Å.

In addition, the insulating film 34 for forming the capacitor lower electrode 34 may include undoped-silicate glass (USG), phospho-silicate glass (PSG), boro-phospho-silicate glass (BPSG), high density plasma (HDP) oxide, and spin on (SOG). A film formed by using a glass film, a TEOS (Tetra Ethyl Ortho Silicate) film or an oxide film using HDP (high densigy plasma), or by oxidizing a silicon substrate at a high temperature between 600 and 1,100 ° C in a thermal oxide (furnace). ).

Subsequently, the insulating layer 35 in the region where the capacitor is to be formed is selectively removed to form the capacitor lower electrode forming hole 36. At this time, the etch stop layer 34 prevents the contact plug 13, which is a lower structure, from being etched.

Subsequently, as shown in FIG. 3B, a portion of the etch stop 34 is wet etched using a solution that selectively etches only the etch stop 34. When a part of the etch stop layer 34 is wet etched, it is an isotropic etch, in which a gap 37 approximately two times to the left and right of the etched depth is formed. As shown in FIG. 3B, it can be seen that a gap 37 is formed by recessing a portion of the insulating film 35 to the inside. Here, the depth of the etch stop layer 34 to be removed by wet etching is adjusted within the range of 50 ~ 5000Å, preferably a solution containing H ₃ PO ₄ as a solution for the wet etching process.

Subsequently, as shown in FIG. 3C, the remaining etch stop layer 34 exposed by the capacitor lower electrode forming hole 36 is removed to expose the contact plug 33.

Subsequently, the lower electrode 38 is formed on the inner surface of the capacitor lower electrode forming hole 36 using the conductive film. When forming the lower electrode, the lower electrode is completely filled in the recessed gap by using a process having excellent step coverage such as atomic layer deposition (ALD) or chemical vapor deposition (CVD).

Although not shown here, in the actual process of forming the lower electrode, the conductive film for the lower electrode is first formed along the pattern of the capacitor lower electrode forming hole 36, and then the insulating film for forming the capacitor lower electrode is formed by using a process such as etch back. A lower electrode is formed by removing the lower electrode conductive film formed on the 35 so that the lower electrode conductive film remains only inside the capacitor lower electrode forming hole 36.

The conductive film may be a polysilicon film, tungsten film (W) or titanium nitride film (TiN), platinum film (Pt), iridium film (Ir), iridium oxide film (IrO ₂ ), ruthenium film (Ru), ruthenium oxide film (RuO ₂ ), Tungsten nitride film (WN), or the like, or a combination thereof is used for lamination.

Although not shown here, a titanium nitride film TiN or a titanium nitride film TiAlN is formed between the lower electrode 38 and the contact plug 33 as a diffusion barrier, and the lower electrode 38 is formed. If the polysilicon layer 38 is not formed, a titanium silicide layer TiSix is formed on the upper end of the contact plug 33 before the lower electrode 38 is formed in order to reduce the contact resistance of the contact plug 33.

Subsequently, as shown in FIG. 3D, the insulating film 35 for forming the capacitor lower electrode used as the formwork is removed. In this case, when only the insulating film 35 for forming the capacitor lower electrode 35 is removed, the lower electrode 38 is bonded to the etch stop layer 34 much wider than the conventional one, and because the lower area is wide, it has a strong structure without falling down. do.

Therefore, according to the present embodiment, when the capacitor lower electrode of the cylinder type is formed, it can be formed more reliably than before, and the bridge phenomenon that is stuck between neighboring capacitor lower electrodes can be eliminated. In addition, the effective area of the capacitor is increased due to the lower electrode adhered to the etch stop layer 34.

Subsequently, as shown in FIG. 3E, a dielectric thin film 39 is formed along the surface of the lower electrode 38. Subsequently, an upper electrode 40 is formed over the conductive film.

As the dielectric thin film, high dielectric materials such as Ta ₂ O ₅ , Al ₂ O ₃ , HfO ₂ , SrTiO ₃ , BST, and ferroelectric materials such as PZT, PLZT, SBT, and BLT are used.

In addition, the conductive film used as the upper electrode may also be a conductive polysilicon film, tungsten film (W) or titanium nitride film (TiN), platinum film (Pt), iridium film (Ir), iridium oxide film (IrO ₂ ), ruthenium film ( Ru), ruthenium oxide film (RuO ₂ ), and tungsten nitride film (WN) may be used.

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.

According to the present invention, when a three-dimensional capacitor having a cylindrical shape is manufactured, the lower electrode can be manufactured more robustly than before. Accordingly, the lower electrode of the cylindrical shape can be formed more reliably than the conventional one, and the bridge phenomenon that is stuck between the adjacent capacitor lower electrodes can be eliminated.

In addition, due to the lower electrode adhered to the etch stop layer, the effect of increasing the surface effective area of the capacitor manufactured in the limited area as in the prior art can be expected.

Claims (9)

Forming an etch stop layer on the substrate on which the predetermined process is completed; Forming an insulating film for forming a capacitor on the etch stop film; Selectively removing the capacitor forming insulating layer in the region where the capacitor is to be formed, to form a capacitor forming hole exposing the etch stop film; Removing a portion of an etch stop layer formed at a lower portion of the capacitor forming insulating layer, which is a peripheral area of the bottom of the capacitor forming hole, to form a gap for forming a lower electrode; Forming a conductive film on an inner surface of the capacitor forming hole, and allowing the conductive film to be filled in the gap for forming the lower electrode, thereby forming a lower electrode having an annular border on an outer wall; Removing the capacitor forming insulating film; Forming a dielectric thin film on a surface of the lower electrode; And Forming an upper electrode on the dielectric thin film Capacitor manufacturing method of a semiconductor device comprising a. The method of claim 1, The gap for forming the lower electrode And a portion of the etch stop film exposed by the capacitor forming hole is subjected to an isotropic etching process. The method of claim 2, The isotropic etching process is a capacitor manufacturing method of a semiconductor device comprising a H ₃ PO ₃ solution. The method of claim 3 And removing a portion of the etch stop layer in the range of 50 to 5000 kV during the isotropic etching process. The method of claim 1, The forming of the lower electrode is a capacitor manufacturing method of a semiconductor device, characterized in that proceeding using atomic layer deposition or chemical vapor deposition. The method of claim 1, And the etch stop layer comprises a silicon nitride layer. The method of claim 6, The etching stop film is a capacitor manufacturing method of the semiconductor device, characterized in that formed in the range of 500 ~ 5000Å. The method of claim 1, And the insulating film for forming a capacitor lower electrode is formed in a range of 5000 to 50000 GHz. An insulating film provided on the substrate; A lower electrode of a cylindrical shape embedded in the insulating film up to an annular edge bonded to the bottom of the outer wall; A dielectric thin film formed on the surface of the lower electrode; And An upper electrode on the dielectric thin film The capacitor of the semiconductor device provided with.

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