KR100557926B1 - pumping capacitor and method for fabricating the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high efficiency pumping capacitor used in a charge pumping circuit and a method of manufacturing the same in a semiconductor memory device.

The pumping capacitor of the present invention comprises: a first electrode acting as a pumping node; A second electrode serving as a pumped node, the second electrode being formed to completely surround the front surface of the first electrode; And a dielectric film filled in the space formed by the second electrode surrounding the first electrode.

Description

Pumping capacitor and method for fabricating the same

1 is a cross-sectional structural view of a conventional pumping capacitor,

2 is a structural diagram of another conventional pumping capacitor,

3 is a structural diagram of a pumping capacitor according to an embodiment of the present invention,

4A to 4D are plan views illustrating a manufacturing process of a pumping capacitor according to an embodiment of the present invention;

5A to 5D are cross-sectional views illustrating a manufacturing process of a pumping capacitor according to an embodiment of the present invention;

6A to 6F are cross-sectional views illustrating a manufacturing process of a pumping capacitor according to another embodiment of the present invention;

(Explanation of symbols for the main parts of the drawing)

30: P well 31: the pumped node (impurity region)

32: pumping node 33, 34: pumped node

35: space 36: field oxide film

37 insulating film 38 interlayer insulating film

39: contact hole 40: source / drain area

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor memory device, and more particularly to a high efficiency pumping capacitor used in a charge pumping circuit and a manufacturing method thereof.

In general, a pumping circuit is a circuit for making a new power source, such as a bulk bias (VBB) and a boosted voltage (VPP), in a semiconductor memory circuit, which is not externally input, and is used in various power supply circuits.

The pumping capacitor is used in such a pumping circuit, Figure 1 shows a cross-sectional structure of a typical representative pumping capacitor. Referring to FIG. 1, a conventional pumping capacitor uses an NMOS transistor, and a source S and a drain D are formed in a P well PW, and a gate (C) is formed on the channel region C between the source and the drain. G) is formed.

The pumping capacitor having the structure as described above is a node in which the source S and the drain D are connected to one node N11 to serve as a pump, and the node N12 connected to the gate G is pumped. Acting as a node, the power to be made through charge pumping is connected to the gate. In the figure, reference numeral N13 denotes a surrounding node.

Figure 2 shows the structure of another conventional pumping capacitor, showing a flat plate capacitor. Referring to FIG. 2, a conventional pumping capacitor has a structure in which a nonconductive dielectric material is filled between two plates P21 and P22 made of a conductive material. At this time, the upper plate (P21) is connected to the pumped node (N22), the lower plate (P22) acts as a pumping node (N21). In the drawings, reference numerals N23 and N24 denote peripheral nodes.

The pumping capacitor of FIGS. 1 and 2 having the structure as described above pumps the charge of the nodes N12 and N22 to be pumped using the capacitance between the nodes N12 and N22 to which the nodes N11 and N21 are pumped. It was.

However, in the conventional pumping capacitor, since the parasitic capacitors C11, C12, C13 and C21, C22 exist between the surrounding nodes N13, N23, N24 and the pumping nodes N11, N21, There is a problem of pumping unwanted charges to other nodes through parasitic capacitors.

The parasitic capacitors as described above have been increasingly generated because other nodes must be arranged around for normal operation and high integration of the device.

Specific examples of the parasitic capacitance present in the conventional pumping capacitor include a parasitic capacitance between the drain and the bulk and a parasitic capacitance between the source and the bulk in the case of a pumping capacitor using a CMOS transistor. Is connected to the same node, there are parasitic capacitances present at the junction between the bulk and the well surrounding the bulk.

In addition, in the case of a pumping capacitor or a flat plate capacitor using a CMOS transistor, parasitic capacitance is formed between other nodes, conductive conductors, or various materials located opposite to the pumping node.

Therefore, when the parasitic capacitor is generated in the pumping capacitor as described above, only a part of energy is transmitted to the pumped node due to the potential change of the pumping node, and the rest is transmitted to the other node through the parasitic capacitor. That is, the pumping node is to pump not only the originally pumped node but also other nodes connected to the parasitic capacitor at the same time.

The present invention is to solve the problems of the prior art as described above, to provide a pumping capacitor and a method of manufacturing the same to form the front of the node to be pumped to surround the pumping node to prevent the occurrence of parasitic capacitors The purpose is.

In order to achieve the above object of the present invention, the present invention comprises: a first electrode acting as a pumping node; A second electrode serving as a pumped node, the second electrode being formed to completely surround the front surface of the first electrode; A pumping capacitor comprising a dielectric film filled in a space formed by a second electrode surrounding the first electrode is provided.

The pumped node includes a lower plate portion formed under the pumping node; An upper plate portion formed on an upper portion of the pumping node; It consists of sidewalls for connecting the upper plate portion and the lower plate portion, and the lower plate portion, the upper plate portion and sidewalls of the pumping node and the pumped node is made of a metal film or polysilicon film.

In addition, the present invention provides a pumping capacitor using a MOS transistor, comprising: a semiconductor substrate in which an active region is defined by a field oxide film; An insulating film formed on the semiconductor substrate; A first conductive layer formed on the insulating film; An impurity region formed in active regions on both sides of the first conductive layer; An interlayer insulating film having a contact hole exposing the impurity region; A second conductive layer filled in the contact hole; A pumping capacitor having a third conductive layer in contact with the source / drain region through the second conductive layer is provided.

The insulating film is a gate insulating film of a MOS transistor, the impurity region is a source / drain region of a MOS transistor, and the first conductive layer is a gate of a MOS transistor.

The first conductive layer serves as a pumping node of the pumping capacitor, and the active region, the second conductive layer and the third conductive layer serve as a pumping node of the pumping capacitor, and a first pumping node of the pumping capacitor. It is formed to surround the conductive layer.

An insulating film and an interlayer insulating film formed in a space between the first conductive layer and the second conductive layer surrounding the first conductive layer and the second conductive layer serve as a dielectric film of the pumping capacitor. The second conductive layer and the third conductive layer are made of a metal film or a polysilicon film.

In addition, the present invention includes a first conductive layer formed on a semiconductor substrate; A first interlayer insulating film formed on the substrate including the first conductive layer; A second conductive layer formed on the first interlayer insulating film; A second interlayer insulating film formed on the first interlayer insulating film including the second conductive layer; A contact hole formed on the first and second interlayer insulating films to expose the first conductive layer; A third conductive layer filled in the contact hole; And a pumping capacitor including a fourth conductive layer formed on the second interlayer insulating layer to contact the first conductive layer through the third conductive layer.

The first conductive layer, the third conductive layer, and the fourth conductive layer act as pumped nodes of a pumping capacitor, and the second conductive layer acts as a pumping node of a pumping capacitor, and the first conductive layer and the third conductive layer It is formed so as to be surrounded by the layer and the fourth conductive layer. The first conductive layer, the second conductive layer, and the third conductive layer are made of a metal film or a polysilicon film.

The first and second interlayer insulating layers formed in the space between the first conductive layer, the third conductive layer, and the fourth conductive layer surrounding the second conductive layer and the second conductive layer serve as dielectric layers of the pumping capacitor.

A method of manufacturing a pumping capacitor using a MOS transistor, the method comprising: forming a field oxide film on a semiconductor substrate to define an active region; Forming a gate insulating film on the semiconductor substrate; Forming a gate on the gate insulating film; Forming a source / drain region in the active region on both sides of the gate; Forming an interlayer insulating film on the entire surface of the substrate; Etching the contact insulating layer so as to expose the source / drain regions by etching the interlayer insulating layer; It provides a method of manufacturing a pumping capacitor comprising the step of forming a conductive layer in contact with the source / drain region through the contact hole.

In addition, the present invention comprises the steps of forming a first conductive layer on a semiconductor substrate; Forming a first interlayer insulating film on the substrate including the first conductive layer; Forming a second conductive layer on the first interlayer insulating film; Forming a second interlayer insulating film on the first interlayer insulating film including the second conductive layer; Etching the first and second interlayer insulating films to form contact holes to expose the first conductive layer; It provides a method of manufacturing a pumping capacitor comprising the step of forming a third conductive layer in contact with the first conductive layer through the contact hole.

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

3 illustrates the structure of a pumping capacitor according to an embodiment of the present invention, wherein the pumping capacitor according to the embodiment of the present invention is a pumping capacitor using a MOS transistor.

Referring to FIG. 3, the pumping capacitor according to the embodiment of the present invention is surrounded by all six surfaces of the front, that is, the front, back, left, and right sides of the pumping node 32 by the pumping nodes 31, 33, and 34 made of a conductive material. The pumping node 32 has a structure that can only be seen by the nodes 31, 33, 34 being pumped.

Since the front side is surrounded by the nodes 31, 33, and 34 where the pumping node 32 is popped, and the space 35 surrounded by the pumped nodes 31, 33, and 34 is filled with dielectric material, By the pumping nodes 31, 33, 34 of conductive material, the pumping node 32 is blocked so that it is completely electrically shielded from external nodes, thereby preventing the formation of parasitic capacitors.

According to the present invention, in the pumping capacitor, the pumping node 32 is a node into which a vibrating potential is input in a pumping circuit as an electrical conductor, and the node to be pumped by transferring energy to the pumped node using a change in the input potential is It is a drive node that has a new potential. The shape of these nodes may be any shape.

The pumped nodes 31, 33, 34 are formed as electrical conductors to surround the pumping node 32 so that dielectric material is filled therebetween, so that the pumping node 32 is completely isolated from other nodes around it.

4A to 4D show a plan view for explaining a method of manufacturing the pumping capacitor of the present invention, and FIGS. 5A to 5D show a method of manufacturing a pumping capacitor using the MOS transistor of the present invention, for example, an NMOS transistor. The cross section for illustration is shown. 5A to 5D illustrate cross-sectional process views taken along line 3A-3A 'of FIG. 3.

Referring to FIG. 5A, a field oxide layer 36 is formed on a P well 30 of a semiconductor substrate to form a field oxide layer 36 to define an active region 31 of a pumping capacitor. Referring to FIG. 5B, an insulating film 37 is formed as a gate oxide film on a semiconductor substrate, and then a gate, which is a node 32 for pumping, is formed by depositing a polysilicon film or a metal film and then patterning the same. Subsequently, a high concentration of n ⁺ impurities are ion implanted into the P well 30 of the substrate to form a source / drain region 40. As a result, the channel region under the pumping node 32 between the source / drain region 40 and the source / drain region 40 serves as a lower plate of the pumped nodes.

Referring to FIG. 5C, an interlayer insulating layer 38 is deposited on a substrate including a pumping node 32, and then the interlayer insulating layer 38 is etched to expose the source / drain regions 40. 39). A metal film or a polysilicon film is deposited on the interlayer insulating film 38 including the contact hole 39 and then etched to remain only in the contact hole 39 so that the conductive layer 33 is filled only in the contact hole 39. Next, as shown in FIG. 5D, a conductive material made of a metal film or a polysilicon film is deposited on the interlayer insulating film 38 corresponding to the active region 31, and then patterned to form the conductive layer 34.

In the above, the conductive layer 33 filled in the contact hole 39 and the conductive layer 34 formed on the interlayer insulating film 38 serve as sidewalls and top plates of the pumped nodes. The gate oxide film 37 and the interlayer insulating film 38 filled in the space 35 between the pumping nodes 31, 33, 34 and the pumping node 32 serve as a dielectric film of the pumping capacitor.

In the above process, the conductive layer 33 and the conductive layer 34 may be formed simultaneously. That is, a metal layer or a polysilicon layer may be formed on the interlayer insulating layer 38 so as to fill the contact hole 39 and then patterned to simultaneously form the conductive layer 33 and the conductive layer 34.

As described above, in the pumping capacitor according to the exemplary embodiment of the present invention, a parasitic junction capacitor is formed between the source / drain region 40 and the P well 30, but the source / drain region 40 is different from the conventional method. Because it acts as a pumped node rather than a pumping node, the pumping capacitor does not have a significant effect on pumping voltage.

6a to 6f show a manufacturing process of the pumping capacitor according to another embodiment of the present invention, the structure and plan view are the same as FIG. 6 is a cross-sectional view taken along line 3A-3A 'of FIG. 3.

As shown in FIG. 6A, a conductive material formed of a metal or polysilicon film is deposited on the semiconductor substrate 51 to form the lower plate 31 of the pumped node as shown in FIG. 4A.

As shown in FIG. 6B, the lower plate 31 is formed, and then an interlayer insulating film 52 is formed on the substrate. A conductive material made of a metal or polysilicon film is deposited on the interlayer insulating film 52, and then patterned. The conductive layer 32 is formed. This conductive layer 32 acts as a pumping node for the pumping capacitor.

As shown in FIG. 6D, after the conductive layer 32 is formed, the interlayer insulating layer 53 is again deposited on the interlayer insulating layer 52, and the interlayer insulating layers 53 and 52 are exposed by the conductive layer 31. Etch to form a contact hole 54.

As shown in FIG. 6E, a metal layer or a polysilicon layer is deposited on the interlayer insulating layer 53 to fill the contact hole 54, and then etched so as to remain only in the contact hole 54 to fill the contact hole 54. ). This conductive layer 33 acts as a sidewall of the pumped node.

As shown in FIG. 6F, a conductive material made of metal or polysilicon is deposited on the interlayer insulating layer 53, and then patterned to be in contact with the conductive layer 33 to form a conductive layer 34 serving as a top plate of a pumped node. It is formed on the insulating film 52. In this case, the conductive layers 33 and 34 may be formed at the same time as described in the embodiment.

Referring to the efficiency of the pumping capacitor according to the embodiment of the present invention as described above are as follows.

In the pumping capacitor of the present invention, a parasitic capacitor generated in a node driven from a conventional pumping capacitor, that is, a pumping node, is not generated. At this time, the current required to charge the conventional parasitic capacitor is represented by the following equation.

Here, ΔV is the potential variation of the pumping node, t is the time taken for the potential variation, and C _PC is the parasitic capacitance.

Therefore, the pumping capacitor of the present invention reduces the current consumption required for pumping by the amount given in the above formula compared with the conventional pumping capacitor. Therefore, a pumping capacitor having a larger capacitance than a conventional pumping capacitor can be formed, and has a high efficiency in terms of area.

As described in detail above, according to the present invention, the pumped node is formed to surround the pumping node, and by filling the dielectric film in the space therebetween, the pumping node is electrically shielded by the pumped node, so that the pumping It is possible to prevent the formation of parasitic capacitors between nodes and surrounding nodes.

Accordingly, since a part of the energy of the pumping node is prevented from being transferred to the parasitic capacitor to obtain a desired pumping effect, it is possible to provide a highly efficient pumping capacitor. In addition, since the efficiency of the pumping capacitor is increased, it is possible to obtain the same efficiency in an area smaller than that of the conventional circuit, so that the chip size can be reduced.                     

In addition, this invention can be implemented in various changes within the range which does not deviate from the summary.

Claims (30)

A first electrode acting as a pumping node; A second electrode formed to completely surround the first electrode and serving as a pumped node; And a dielectric film formed to fill the space formed by the second electrode surrounding the first electrode. The pumping capacitor of claim 1, wherein the first electrode is formed of a metal film or a polysilicon film. The method of claim 1, wherein the second electrode A lower plate portion formed under the first electrode; An upper plate portion formed on the first electrode; Pumping capacitor, characterized in that consisting of a side wall for electrically connecting the upper plate portion and the lower plate portion. The pumping capacitor of claim 3, wherein the lower plate portion, the upper plate portion, and the sidewall of the second electrode are formed of a metal film or a polysilicon film. In a pumping capacitor using a MOS transistor, A semiconductor substrate whose active region is defined by a field oxide film; An insulating film formed on the semiconductor substrate; A first conductive layer formed on the insulating film; An impurity region formed on both sides of the first conductive layer of the active region; An interlayer insulating film having a contact hole exposing the impurity region; A second conductive layer formed in the contact hole; And a third conductive layer formed on the interlayer insulating layer to be in contact with the second conductive layer and electrically connected to the source / drain regions. The pumping capacitor of claim 5, wherein the insulating layer is a gate insulating layer of a MOS transistor, the impurity region is a source / drain region of a MOS transistor, and the first conductive layer is a gate of a MOS transistor. 7. The pumping capacitor of claim 6, wherein the first conductive layer acts as a pumping node of the pumping capacitor. 8. The pumping capacitor of claim 7, wherein the first conductive layer is made of a metal film or a polysilicon film. The pumping capacitor of claim 7, wherein the active region, the second conductive layer, and the third conductive layer are formed to surround the first conductive layer and serve as a pumped node. The pumping capacitor of claim 9, wherein the second conductive layer and the third conductive layer are made of a metal film or a polysilicon film. The pumping capacitor of claim 9, wherein an insulating film and an interlayer insulating film between the second and third conductive layers surrounding the first conductive layer serve as a dielectric film. A first conductive layer formed on the semiconductor substrate; A first interlayer insulating film formed on the first conductive layer; A second conductive layer patterned on the first interlayer insulating film; A second interlayer insulating film formed on the first interlayer insulating film including the second conductive layer; A contact hole formed to expose the first conductive layer on the first and second interlayer insulating films; A third conductive layer filled in the contact hole and formed to be in contact with the first conductive layer; And a fourth conductive layer on the interlayer insulating layer, the fourth conductive layer being in contact with the third conductive layer and electrically connected to the first conductive layer. The pumping capacitor of claim 12, wherein the first conductive layer, the third conductive layer, and the fourth conductive layer serve as a pumped node. The pumping capacitor of claim 13, wherein the first conductive layer is formed of a metal film or a polysilicon film. The pumping capacitor of claim 12, wherein the second conductive layer is formed to be surrounded by the first conductive layer, the third conductive layer, and the fourth conductive layer to act as a pumping node. The pumping capacitor of claim 15, wherein the second conductive layer and the third conductive layer are made of a metal film or a polysilicon film. The pumping capacitor of claim 15, wherein the first and second interlayer insulating films formed in the space between the first, third and fourth conductive layers surrounding the second conductive layer serve as a dielectric film. In the method of manufacturing a pumping capacitor using a MOS transistor, Forming a field oxide film on the semiconductor substrate to define an active region; Forming a gate insulating film on the semiconductor substrate; Forming a gate on the gate insulating film; Forming a source / drain region on both sides of the gate of the active region; Forming an interlayer insulating film on the semiconductor substrate to cover the gate; Forming a contact hole by etching the interlayer insulating layer to expose the source / drain regions; And forming a conductive layer in contact with the source / drain region through the contact hole. 19. The method of claim 18, wherein the gate acts as a pumping node. 20. The method of claim 19, wherein the gate capacitor is formed to surround the gate which is a node for pumping the active region and the conductive layer. The method of manufacturing a pumping capacitor according to claim 20, wherein the conductive layer is formed of a metal film or a polysilicon film. 22. The method of claim 21, wherein the conductive layer is formed on the first conductive layer filling the contact hole and the second conductive layer in contact with the source / drain region through the first conductive layer on the interlayer insulating film. The manufacturing method of the pumping capacitor. 23. The method of claim 22, wherein the first and second interlayer insulating films formed in the space between the first and second conductive layers surrounding the gate serve as a dielectric film. Forming a first conductive layer on the semiconductor substrate; Forming a first interlayer insulating film on the first conductive layer; Forming a patterned second conductive layer on the first interlayer insulating film; Forming a second interlayer insulating film on the first interlayer insulating film including the second conductive layer; Forming a contact hole by etching the first and second interlayer insulating layers to expose the first conductive layer so as to surround the second conductive layer; And forming a third conductive layer contacting with the first conductive layer through the contact hole. 25. The method of claim 24, wherein the first conductive layer acts as a pumping node. 27. The method of claim 25, wherein the first conductive layer is formed of a metal film or a polysilicon film. 26. The method of claim 25, wherein the first conductive layer and the third conductive layer are formed to surround the first conductive layer, which is a pumping node, and act as a pumped node. 28. The method of claim 27, wherein the first conductive layer and the third conductive layer are formed of a metal film or a polysilicon film. 29. The method of claim 28, wherein the third conductive layer is formed of a first portion filling the contact hole and a second conductive layer contacting the first conductive layer through the first portion on the interlayer insulating film. The manufacturing method of the pumping capacitor. 29. The method of claim 28, wherein the first and second interlayer insulating films formed in the space between the first and third conductive layers surrounding the second conductive layer serve as a dielectric film.

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