US20040033630A1

US20040033630A1 - Charge pump or other charge storage capacitor including PZT layer for combined use as encapsulation layer and dielectric layer of ferroelectric capacitor and a method for manufacturing the same

Info

Publication number: US20040033630A1
Application number: US10/620,681
Authority: US
Inventors: Glen Fox; Thomas Evans
Original assignee: Ramtron International Corp
Current assignee: Ramtron International Corp
Priority date: 2001-05-22
Filing date: 2003-07-15
Publication date: 2004-02-19
Also published as: US6492673B1; US20030067027A1; US20020175361A1

Abstract

A charge storage capacitor includes a bottom electrode, a dielectric layer formed on the bottom electrode, and a local interconnect electrode formed on the dielectric layer, wherein the dielectric layer is an encapsulation layer, and a ferroelectric memory cell includes the charge storage capacitor.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional filing of co-pending U.S. patent application Ser. No. 10/288/137, filed Nov. 4, 2002, which is a divisional filing of U.S. patent application Ser. No. 09/863,365 filed May 22, 2001 (now U.S. Pat. No. 6,493,673), which are hereby incorporated by reference in their entirety.[0001]

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a charge storage capacitor and more particularly, to a charge storage capacitor including an encapsulation layer that can also function as a dielectric layer of the charge storage capacitor.

2. Discussion of the Related Art

Integrated circuit ferroelectric memory devices include an integrated circuit substrate which includes a cell region and a periphery region. A plurality of ferroelectric memory cells are formed in the cell region, including a plurality of ferroelectric capacitors. The ferroelectric capacitor in the ferroelectric memory cell includes a dielectric material that has a high dielectric constant and that can be polarized by an electric field, thus storing a memory data state. A polarization of the dielectric material remains until reversed by an opposite electrical field. This makes the dielectric memory cell non-volatile.

Conventionally, capacitors with a single ferroelectric layer, such as a PZT-F layer (ferroelectric layer formed of PZT (lead zirconate titanate)), are used for making both switchable ferroelectric capacitors (data storage capacitors) and charge pump capacitors or other charge storage capacitors. However, it is very difficult to optimize the ferroelectric properties of a ferroelectric layer, such as a PZT-F layer, for high permittivity capacitor applications such as charge pumps or other charge storage capacitors. Further, conventionally, an encapsulation layer, such as a PZT-E layer (encapsulation layer formed of PZT (lead zirconate titanate)) is utilized only for encapsulating and protecting the underlying ferroelectric capacitor including the PZT-F layer.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a charge storage capacitor that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide an improved charge storage capacitor.

Another object of the present invention is to provide a capacitor including a dielectric layer that is easy to optimize for both encapsulation and high permittivity dielectric properties.

Another object of the present invention is to provide a capacitor having a high charge storage capability that has low leakage current and relatively linear capacitance dependence on voltage.

Another object of the present invention is to provide an integrated circuit, including an improved charge storage and a ferroelectric memory cell, having a simple manufacture process.

Additional features and advantages of the invention will be set forth in the description, which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a charge storage capacitor includes a bottom electrode, a dielectric layer formed on the bottom electrode, and a local interconnect electrode formed on the dielectric layer.

In another aspect of the present invention, an integrated circuit including a capacitor includes a bottom, a first dielectric layer formed on the bottom electrode, a top electrode formed on the first dielectric layer, a second dielectric layer formed on the top electrode, wherein the second dielectric layer completely covers the top electrode, and a local interconnect electrode formed on the second dielectric layer.

In another aspect of the present invention, a charge storage capacitor includes a bottom electrode, a first dielectric layer formed on the bottom electrode, a second dielectric layer formed on the first dielectric layer, and a local interconnect electrode formed on the second dielectric layer.

In another aspect of the present invention, a method for forming a capacitor, includes the steps of forming a bottom electrode, forming an encapsulation layer on the bottom electrode, and forming a local interconnect electrode on the encapsulation layer.

In another aspect of the present invention, a method for forming an integrated circuit, comprising a charge storage capacitor and a ferroelectric memory cell including a data storage capacitor, includes the steps of forming a bottom electrode of the charge storage capacitor and a bottom electrode of the data storage capacitor on an integrated circuit, forming a ferroelectric layer on the bottom electrode of the data storage capacitor, forming a top electrode on the ferroelectric layer, forming a first encapsulation layer on the bottom electrode of the charge storage capacitor and a second encapsulation layer on the bottom electrode of the data storage capacitor including the ferroelectric layer and the top electrode, wherein the first encapsulation layer and the second encapsulation are formed simultaneously, and forming a first interlayer dielectric layer on the first encapsulation layer and a second interlayer dielectric layer on the second encapsulation layer, wherein the first encapsulation layer is a dielectric layer of the charge storage capacitor.

In another aspect of the present invention, a method for forming an integrated circuit comprising a capacitor, includes the steps of forming a bottom electrode, forming a ferroelectric layer on the bottom electrode, forming a top electrode on the ferroelectric layer, forming an encapsulation layer on the top electrode, wherein the encapsulation layer completely covers the top electrode, and forming a local interconnect electrode on the encapsulation layer, wherein the ferroelectric layer includes PZT.

In another aspect of the present invention, a method for forming an integrated circuit, comprising a charge storage capacitor and a ferroelectric memory cell including a data storage capacitor, includes the steps of forming a bottom electrode of the charge storage capacitor and a bottom electrode of the data storage capacitor on an integrated circuit substrate, forming a first ferroelectric layer on the bottom electrode of the charge storage capacitor and a second ferroelectric layer on the bottom electrode of the data storage capacitor, forming a first top electrode on the first ferroelectric layer and a second top electrode on the second ferroelectric layer, forming a first encapsulation layer on the bottom electrode of the charge storage capacitor, including the first ferroelectric layer and the first top layer, forming a second encapsulation layer on the bottom electrode of the data storage capacitor, including the second ferroelectric layer and the second top layer, wherein the first encapsulation layer and the second encapsulation are formed simultaneously, forming a first interlayer dielectric layer on the first encapsulation layer and a second interlayer dielectric layer on the second encapsulation layer, etching the first interlayer dielectric layer to form a first opening to expose the first encapsulation layer, etching the second interlayer dielectric layer and the second encapsulation layer to form a second opening to expose the top electrode of the data storage capacitor, and forming a first local interconnect electrode in the first opening and a second local interconnect electrode in the second opening, simultaneously, wherein the first local interconnect electrode comprises part of the charge storage capacitor.

In another aspect of the present invention, a method for forming a capacitor, includes the steps of forming a bottom electrode, forming a ferroelectric layer on the bottom electrode, forming an encapsulation layer on the ferroelectric layer, and forming a local interconnect electrode on the encapsulation layer.

In another aspect of the present invention, a method for forming an integrated circuit, comprising a charge storage capacitor and a ferroelectric memory cell including a data storage capacitor, includes the steps of forming a bottom electrode of the charge storage capacitor and a bottom electrode of the data storage capacitor on an integrated circuit substrate, forming a first ferroelectric layer on the bottom electrode of the charge storage capacitor and a second ferroelectric layer on the bottom electrode of the data storage capacitor, forming a top electrode layer on the first and second ferroelectric layers, etching the top electrode layer to remove from the first ferroelectric layer and to form a to electrode of the data storage capacitor on the second ferroelectric layer, forming a first encapsulation layer on the bottom electrode of the charge storage capacitor including the first encapsulation layer and a second encapsulation layer on the bottom electrode of the data storage capacitor including the second ferroelectric layer and the top electrode, and forming a first interlayer dielectric layer on the first encapsulation layer and a second interlayer dielectric layer on the second encapsulation layer, wherein the first encapsulation layer and the second encapsulation are formed simultaneously.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings: [0023]
FIG. 1 is a cross sectional view of a ferroelectric memory cell; [0024]
FIGS. [0025] 2A-2F are sequential cross sectional views of an integrated circuit including a charge storage capacitor according to a first embodiment of the present invention;
FIGS. [0026] 3A-3F are sequential cross sectional views of an integrated circuit including a charge storage capacitor according to a second embodiment of the present invention;
FIGS. [0027] 4A-4F are sequential cross sectional views of an integrated circuit including a charge storage capacitor according to a third embodiment of the present invention; and
FIGS. [0028] 5A-5F are sequential cross sectional views of an integrated circuit including a charge storage capacitor according to a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. [0029]
FIG. 1 shows a cross sectional view of a typical ferroelectric memory cell structure including a ferroelectric capacitor, which stores a memory data state. The ferroelectric capacitor includes a bottom electrode (BE) [0030] 111, a PZT-F layer 112, and a top electrode (TE) 113. The ferroelectric memory cell further includes an encapsulation PZT (PZT-E) layer 114 formed on the ferroelectric capacitor to protect the underlying capacitor from being damaged during etching of the bottom electrode 111. Once the etching of the bottom electrode is finished, an interlevel dielectric (ILD) layer 150 is deposited. Thereafter, the interlevel dielectric layer 150 and the PZT-E layer 114 are etched to form an opening so that a local interconnect electrode (LI) 115 can be formed to be in contact with the top electrode 113 through the opening.
FIGS. [0031] 2A-2E show sequential cross sectional views of an integrated circuit including a charge storage capacitor according to a first embodiment of the present invention. The integrated circuit includes the charge storage capacitor of the present invention and a ferroelectric memory cell including a ferroelectric capacitor (data storage capacitor). The charge storage capacitor of the present invention and the data storage capacitor are formed simultaneously on an integrated circuit substrate by using the same process sequence.
FIG. 2A shows the integrated circuit including a [0032] section 210 a, where the charge storage capacitor of the present invention is to be formed, and a section 210 b, where the ferroelectric capacitor (data storage capacitor) is to be formed. The integrated circuit shown in FIG. 2A includes a CMOS underlayer coated with SiO₂or other interlayer dielectric layer 241, with an adhesion layer (not shown) formed thereon, and a bottom electrode layer 211 deposited thereon. The adhesion layer can be formed of Ti or TiO_xhaving a thickness of about 20 nm, for example. The bottom electrode layer can be made of Pt (Platinum) having a thickness of about 100 nm, for example. On the bottom electrode layer 211, a PZT-F 212 is deposited to a thickness in a range of between 150-200 nm. Then, a top electrode layer 213 is deposited to a thickness of 150 nm, for example.
Thereafter, the [0033] top electrode layer 213 in 210 b is patterned by photolithography and reactive ion etching to form a top electrode (TE) 213 b of the data storage capacitor. The top electrode layer 213 in 210 a is completely removed by the reactive ion etching (RIE), as shown in FIG. 2B.
Thereafter, the PZT-[0034] F layer 212 in 210 b is patterned by photolithography and reactive ion etching to form a PZT-F layer 212 b. Simultaneously, the PZT-F 212 in 210 a is completely removed by reactive ion etching, thus leaving a clean bottom electrode layer surface in 210 a, as shown in FIG. 2C.
Then, an encapsulation layer formed of PZT (PZT-E layer) [0035] 214 is formed to a thickness in a range of between 30 to 200 nm, for example. Thereafter, the PZT-E layer 214 is patterned by photolithography and reactive ion etching to form a dielectric layer 214 a of the charge storage capacitor and an encapsulation layer 214 b of the data storage capacitor. Also, the bottom electrode layer 211 is patterned by photolithography and reactive ion etching to form a bottom electrode 211 a of the charge storage capacitor and a bottom electrode 211 b of the data storage capacitor, as shown in FIG. 2D.
Once the [0036] bottom electrodes 211 a and 211 b and the PZT- E layers 214 a and 214 b are formed, an interlayer dielectric layer 250 is deposited. Thereafter, the interlayer dielectric layer 250 and the PZT-E layer 214 b formed on the data storage capacitor in 210 b are etched through to form an opening to provide access to the top, electrode 213 b of the data storage capacitor. Simultaneously, the interlayer dielectric layer 250 formed in 210 a is etched, without etching the PZT-E layer 214 a, to form an opening therein, as shown in FIG. 2E.
Thereafter, a local interconnect layer [0037] 215 is deposited and patterned by photolithography and reactive ion etching to form a local interconnect electrode 215 b of the ferroelectric memory cell in 210 b and a local interconnect electrode 215 a of the charge storage capacitor in 210 a, simultaneously, as shown in FIG. 2F. The local interconnect electrode 215 a is also a second electrode of the charge storage capacitor. The local interconnect layer can be made of conductive materials, such as TiN and Al, for example.
In this embodiment, the charge storage capacitor includes the encapsulation PZT (PZT-E) [0038] layer 214 a as a dielectric layer of the capacitor. Further, in this embodiment, the bottom electrode (BE) 211 a is used as a first electrode and the local interconnect layer (LI) 215 a is used as a second electrode of the charge storage capacitor.
The PZT-E layer [0039] 214 can be formed by electron beam deposition, flash deposition, ion plating, Rf-magnetron sputtering, ion beam sputtering, laser ablation, molecular beam epitaxy (MBE), chemical vapor deposition (CVD), plasma CVD or MOCVD, or sol-gel method. By depositing the PZT layer with properly adjusted Pb concentration with high temperature deposition, up to 700° C., or by changing deposited Pb concentration, enhanced linear dielectric response and reduced leakage current can be provided. Further, as part of the manufacture process, it is also possible to plasma damage the PZT layer during the etching of the bottom electrode layer and the PZT-E layer, thereby improving the linear dielectric performance of the PZT layer.
FIGS. [0040] 3A-3G show sequential cross sectional views of an integrated circuit including a charge storage capacitor according to a second embodiment of the present invention. The charge storage capacitor and a ferroelectric capacitor (data storage capacitor) are formed simultaneously on an integrated circuit substrate by using the same process sequence.
FIG. 3A shows the integrated circuit including a [0041] section 310 a, where the charge storage capacitor is to be formed, and a section 310 b, where the data storage capacitor is to be formed. The integrated circuit shown in FIG. 3A includes a CMOS underlayer coated with SiO₂or other interlayer dielectric layer 341, with an adhesion layer (not shown) formed thereon, and a bottom electrode layer 311 deposited thereon. The adhesion layer can be formed of Ti or TiO_xhaving a thickness of about 20 nm, for example. The bottom electrode layer can be made of Pt (Platinum) having a thickness of about 100 nm, for example. On the bottom electrode layer 311, a PZT-F 312 is deposited to a thickness in a range of between 150-200 nm. Then, a top electrode layer 313 is deposited to a thickness of 150 nm, for example.
Thereafter, the [0042] top electrode layer 313 is patterned by photolithography and reactive ion etching to form a top electrode (TE) 313 a of the charge storage capacitor and a top electrode (TE) 313 b of the data storage capacitor, as shown in FIG. 3B.
Thereafter, the PZT-[0043] F 312 layer in 310 b is patterned by photolithography and reactive ion etching to form a PZT-F layer 312 b. Simultaneously, the PZT-F 312 in 310 a is patterned by photolithography and reactive ion etching to form a PZT-F layer 312 a, as shown in FIG. 3C. An area of the PZT-F layer 312 a must be larger than an area of the charge storage capacitor.
Then, a PZT-E layer [0044] 314 is formed to a thickness in a range of between 30 to 200 nm, for example. Thereafter, the PZT-E layer 314 is patterned by photolithography and reactive ion etching to form a dielectric layer 314 a of the charge storage capacitor and an encapsulation layer 314 b of the data storage capacitor. Also, the bottom electrode layer 311 is patterned by photolithography and reactive ion etching to form a bottom electrode 311 a of the charge storage capacitor and a bottom electrode 311 b of the data storage capacitor, as shown in FIG. 3D. An area of the PZT-E layer 314 a and the bottom electrode (BE) 311 a of the charge storage capacitor must be longer than an area of the shorter of the two electrodes constituting the charge storage capacitor.
Once the [0045] bottom electrodes 311 a and 311 b and the PZT- E layers 314 a and 314 b are formed, an interlayer dielectric layer 350 is deposited. Thereafter, the interlayer dielectric layer 350 and the PZT-E layer 314 b formed on the data storage capacitor in 310 b are etched through to form an opening to provide access to the top electrode 313 b of the data storage capacitor. Simultaneously, the interlayer dielectric layer 350 formed in 310 a is etched, without etching the PZT-E layer 314 a, to form an opening therein, as shown in FIG. 3E.
Thereafter, a local interconnect layer [0046] 315 is deposited and patterned by photolithography and reactive ion etching to formed a local interconnect electrode (LI) 315 b of the ferroelectric memory cell in 310 b and a local interconnect electrode 315 a of the charge storage capacitor in 310 a, as shown in FIG. 3F. The local interconnect electrode 315 a of the charge storage capacitor is also a second electrode of the charge storage capacitor. The local interconnect layer can be made of conductive materials, such as TiN and Al, for example.
In this embodiment, the charge storage capacitor includes the [0047] top electrode 313 a, the PZT-E layer 314 a, and the local interconnect electrode 315 a formed on the bottom electrode 311 a and the PZT-F layer 312 a. In this embodiment, the bottom electrode 311 a and the PZT-F layer 312 a remain as part of the capacitor structure, but they are electrically isolated from the rest of the charge storage capacitor. There is an electrical connection to the top electrode 313 a, but there is no electrical connection to the bottom electrode 311 a, thus neither the bottom electrode 311 a nor the PZT-F layer 312 a has any electrical function in the charge storage capacitor.
FIGS. [0048] 4A-4G show sequential cross sectional views of an integrated circuit including a charge storage capacitor according to a third embodiment of the present invention. The charge storage capacitor and a ferroelectric capacitor (data storage capacitor) are formed simultaneously on an integrated circuit substrate by using the same process sequence.
FIG. 4A shows the integrated circuit including a [0049] section 410 a, where the charge storage capacitor is to be formed, and a section 410 b, where the data storage capacitor is to be formed. The integrated circuit shown in FIG. 4A includes a CMOS underlayer coated with SiO₂or other interlayer dielectric layer 441, with an adhesion layer (not shown) formed thereon, and a bottom electrode layer 411 deposited thereon. The adhesion layer can be formed of Ti or TiO_xhaving a thickness of about 20 nm, for example. The bottom electrode layer can be made of Pt (Platinum) having a thickness of about 100 nm, for example. On the bottom electrode layer 411, a PZT-F 412 is deposited to a thickness in a range of between 150-200 nm. Then, a top electrode layer 413 is deposited to a thickness of 150 nm, for example.
Thereafter, the [0050] top electrode layer 413 in 410 b is patterned by photolithography and reactive ion etching to form a top electrode 413 b of the data storage capacitor and the top electrode layer 413 in 410 a is removed by reactive ion etching, as shown in FIG. 4B.
Thereafter, the PZT-[0051] F 412 in 410 b is patterned by photolithography and reactive ion etching to form PZT- F layers 412 a and 412 b, as shown in FIG. 4C.
Then, a PZT-E layer [0052] 414 is formed to a thickness in a range of between 30 to 200 nm, for example. Thereafter, the PZT-E layer 414 is patterned by photolithography and reactive ion etching to form 414 a and 414 b. Also, the bottom electrode layer 411 is patterned by photolithography and reactive ion etching to form a bottom electrode 411 a of the charge storage capacitor and a bottom electrode 411 b of the data storage capacitor, as shown in FIG. 4D.
Once the [0053] bottom electrodes 411 a and 411 b and the PZT- E layers 414 a and 414 b are formed, an interlayer dielectric layer 450 is deposited. Thereafter, the interlayer dielectric layer 450 and the PZT-E layer 414 b formed on the data storage capacitor in 410 b are etched through to form an opening to provide access to the top electrode 413 b of the data storage capacitor. Simultaneously, the interlayer dielectric layer 450 formed in 410 a is etched, without etching the PZT-E layer 414 a, to form an opening therein, as shown in FIG. 4F.
Thereafter, a local interconnect layer [0054] 415 is deposited and patterned by photolithography and reactive ion etching to form a local interconnect electrode 415 b of the ferroelectric memory cell in 410 b and a local interconnect electrode 415 a of the charge storage capacitor in 410 a, as shown in FIG. 4G. The local interconnect electrode 415 a is also a second electrode of the charge storage capacitor. The local interconnect layer can be made of conductive materials, such as TiN and Al, for example.
In this embodiment, the charge storage capacitor includes both the PZT-F layer and the PZT-E layer as a dielectric layer of the capacitor. Since the PZT-E layer can be easily optimized for better charge storage characteristics, such as voltage linearity, for example, than the PZT-F layer, the combined PZT-F and PZT-E layers will improve the capacitor performance of the charge storage capacitor in comparison with using the PZT-F layer alone. [0055]
In a method for forming the PZT-E layer and the PZT-F layer, in addition to using different processes, different compositions, which include changing the concentrations of Pb, Zr, and/or Ti, as well as dopant concentrations, can be used. For example, the PZT-E layer can be deposited with a lower Pb concentration than that of the PZT-F layer, thereby providing the layer with reduced leakage current without a dramatic decrease in permittivity. As part of the processing, it is also possible to plasma damage the PZT-E layer during the top electrode, bottom electrode, PZT-E, and PZT-F etching processes, thereby improving the linear dielectric performance of the PZT-E layer. [0056]
FIGS. [0057] 5A-5G show sequential cross sectional views of an integrated circuit including a charge storage capacitor according to a fourth embodiment of the present invention. The charge storage capacitor and a ferroelectric capacitor (data storage capacitor) are formed simultaneously on an integrated circuit substrate by using the same process sequence.
FIG. 5A shows the integrated circuit including a [0058] section 510 a, where the charge storage capacitor is to be formed, and a section 510 b, where the data storage capacitor is to be formed. The integrated circuit shown in FIG. 5A includes a CMOS underlayer coated with SiO₂or other interlayer dielectric layer 541, with an adhesion layer (not shown) formed thereon, and a bottom electrode layer 511 deposited thereon. The adhesion layer can be formed of Ti or TiO_xhaving a thickness of about 20 nm, for example. The bottom electrode layer can be made of Pt (Platinum) having a thickness of about 100 nm, for example. On the bottom electrode layer 511, a PZT-F 512 is deposited to a thickness in a range of between 150-200 nm. Then, a top electrode layer 513 is deposited to a thickness of 150 nm, for example.
Thereafter, the [0059] top electrode layer 513 is patterned by photolithography and reactive ion etching to form a top electrode 513 b of the data storage capacitor and a top electrode 513 a of the charge storage capacitor, as shown in FIG. 5B.
Thereafter, the PZT-[0060] F 512 in 510 b is patterned by photolithography and reactive ion etching to form a PZT-F layer 513 b. Simultaneously, the PZT-F 513 in 510 a is patterned by photolithography and reactive ion etching to form a PZT-F layer 513 a, as shown in FIG. 5C.
Then, a PZT-E layer [0061] 514 is formed to a thickness in a range of between 30 to 200 nm, for example. Thereafter, the PZT-E layer 514 is patterned by photolithography and reactive ion etching to form an encapsulation layer 514 b of the data storage capacitor and a dielectric layer 514 a of the charge storage capacitor. Also, the bottom electrode layer 511 is patterned by photolithography and reactive ion etching to form a bottom electrode 511 a of the charge storage capacitor and a bottom electrode 511 b of the data storage capacitor, as shown in FIG. 5D.
Once the [0062] bottom electrodes 511 a and 511 b and the PZT- E layers 514 a and 514 b are formed, an interlayer dielectric layer 550 is deposited. Thereafter, the interlayer dielectric layer 550 and the PZT-E layer 514 b formed on the data storage capacitor in 510 b are etched through to form an opening to provide access to the top electrode 513 b of the data storage capacitor. Simultaneously, the interlayer dielectric layer 550 formed on the charge storage capacitor in 510 a is etched, without etching the PZT-E layer 514 a, to form an opening therein, as shown in FIG. 5F.
Thereafter, a local interconnect layer [0063] 515 is deposited and patterned by photolithography and reactive ion etching to formed a local interconnect electrode 515 b of the ferroelectric memory cell in 510 b and a local interconnect electrode 515 a of the charge storage capacitor in 510 a, as shown in FIG. 5G. The local interconnect electrode 515 a is a second electrode of the charge storage capacitor. The local interconnect layer can be made of conductive materials, such as TiN and Al, for example.
The charge storage capacitor in this embodiment has a similar structure to the structure of the second embodiment of the present invention, except for the [0064] bottom electrode 511 a being a first electrode of the charge storage capacitor in this embodiment. The charge storage capacitor in this embodiment includes both the PZT-F layer 512 a and the PZT-E layer 514 a, with the bottom electrode 511 a being the first electrode and the local interconnect electrode 515 a being the second electrode of the charge storage capacitor. In this embodiment, there is no electrical connection to the top electrode 513 a. The top electrode 513 a is effectively a floating electrode. Effectively, there are two capacitors connected in series. The entire stack, including the bottom electrode 511 a, the PZT-F layer 512 a, the top electrode 513 a, the PZT-E layer 514 a, and the local interconnect electrode 515 a, is electrically active. The charge storage capacitor of this embodiment provides improved linearity and higher breakdown voltage in comparison with a capacitor formed with only a PZT-F layer.
In the present invention, the PZT-E layer can be replaced with other materials, such as other Pb-based perovskite dielectrics, aluminum oxide, tantalum oxide, BaTiO[0065] ₃, or other dielectrics, for example.
The charge storage capacitor of the present invention can be used as part of the ferroelectric memory cell or as part of the circuitry in the periphery outside the ferroelectric memory cell. [0066]
By using the structures and the methods described above, a memory cell with an encapsulation layer and a charge storage capacitor using the encapsulation layer as a dielectric can be formed simultaneously, thus providing a simplified manufacturing process. Further, by using the structures and the methods described above, charge pumps or other charge storage capacitors having a high permittivity dielectric can be formed. [0067]
It will be apparent to those skilled in the art that various modifications and variations can be made in the charge storage capacitor of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention if they come within the scope of any claims and their equivalents. [0068]

Claims

1. A method for forming an integrated circuit, comprising a charge storage capacitor and a ferroelectric memory cell including a data storage capacitor, comprising the steps of:

forming a bottom electrode of the charge storage capacitor and a bottom electrode of the data storage capacitor on an integrated circuit substrate;

forming a ferroelectric layer on the bottom electrode of the data storage capacitor;

forming a top electrode layer on the ferroelectric layer;

forming a first encapsulation layer on the bottom electrode of the charge storage capacitor and a second encapsulation layer on the bottom electrode of the data storage capacitor including the ferroelectric layer and the top electrode, wherein the first encapsulation layer and the second encapsulation are formed simultaneously; and

forming a first interlayer dielectric layer on the first encapsulation layer and a second interlayer dielectric layer on the second encapsulation layer,

wherein the first encapsulation layer is a dielectric layer of the charge storage capacitor.

2. The method for forming an integrated circuit according to claim 1, wherein the first and second encapsulation layers comprise PZT.

3. The method for forming an integrated circuit according to claim 2, wherein the first and second encapsulation layers are formed at a temperature as high as 700° C.

4. The method for forming an integrated circuit according to claim 2, wherein the first and second encapsulation layers are formed with plasma damage to improve linear dielectric performance.

5. The method for forming an integrated circuit according to claim 1, wherein the first and second encapsulation layers include Pb-based perovskite dielectrics, aluminum oxide, tantalum oxide, BaTiO₃, or other dielectrics.

6. The method for forming an integrated circuit according to claim 1, further comprising the steps of:

etching the first interlayer dielectric layer to form a first opening to expose the first encapsulation layer;

etching the second interlayer dielectric layer and the second encapsulation layer to form a second opening to expose the top electrode of the data storage capacitor; and

forming a first local interconnect electrode in the first opening and a second local interconnect electrode in the second opening.

7. The method for forming an integrated circuit according to claim 2, wherein the first local interconnect electrode comprises part of the charge storage capacitor.

8. A method for forming an integrated circuit, comprising a charge storage capacitor and a ferroelectric memory cell including a data storage capacitor, comprising the steps of:

forming a first ferroelectric layer on the bottom electrode of the charge storage capacitor and a second ferroelectric layer on the bottom electrode of the data storage capacitor;

forming a first top electrode on the first ferroelectric layer and a second top electrode on the second ferroelectric layer;

forming a first encapsulation layer on the bottom electrode of the charge storage capacitor, including the first ferroelectric layer and the first top layer;

forming a second encapsulation layer on the bottom electrode of the data storage capacitor, including the second ferroelectric layer and the second top layer, wherein the first encapsulation layer and the second encapsulation are formed simultaneously;

forming a first local interconnect electrode in the first opening and a second local interconnect electrode in the second opening,

wherein the first local interconnect electrode comprises part of the charge storage capacitor.

9. The method for forming an integrated circuit according to claim 8, wherein the first and second encapsulation layers comprise PZT.

10. The method for forming an integrated circuit according to claim 9, wherein the first and second encapsulation layers are formed at a temperature as high as 700° C.

11. The method for forming an integrated circuit according to claim 9, wherein the first and second encapsulation layers are formed with plasma damage to improve linear dielectric performance.

12. The method for forming an integrated circuit according to claim 8, wherein the first and second encapsulation layers include Pb-based perovskite dielectrics, aluminum oxide, tantalum oxide, BaTiO₃, or other dielectrics.

13. The method for forming an integrated circuit according to claim 8, wherein the bottom electrode is electrically isolated.

14. The method for forming an integrated circuit according to claim 8, wherein the top electrode is electrically isolated.

15. The method for forming an integrated circuit according to claim 8, wherein the bottom electrode forms a first electrode of the charge storage capacitor, the first ferroelectric layer and the first encapsulation layer form a dielectric layer of the charge storage capacitor, and the first local interconnect electrode forms a second electrode of the charge storage capacitor.

16. The method for forming an integrated circuit according to claim 8, wherein the first top electrode forms a first electrode of the charge storage capacitor, the first encapsulation layer forms a dielectric layer of the charge storage capacitor, and the first local interconnect electrode forms a second electrode of the charge storage capacitor.

17. A method for forming an integrated circuit, comprising a charge storage capacitor and a ferroelectric memory cell including a data storage capacitor, comprising the steps of:

forming a top electrode layer on the first and second ferroelectric layers;

etching the top electrode layer to remove from the first ferroelectric layer and to form a top electrode of the data storage capacitor on the second ferroelectric layer;

forming a first encapsulation layer on the bottom electrode of the charge storage capacitor including the first encapsulation layer and a second encapsulation layer on the bottom electrode of the data storage capacitor including the second ferroelectric layer and the top electrode; and

wherein the first encapsulation layer and the second encapsulation are formed simultaneously.

18. The method for forming an integrated circuit according to claim 17, wherein the first and second encapsulation layers comprise PZT.

19. The method for forming an integrated circuit according to claim 17, wherein the first and second encapsulation layers include Pb-based perovskite dielectrics, aluminum oxide, tantalum oxide, BaTiO₃, or other dielectrics.

20. The method for forming an integrated circuit according to claim 17, further comprising the steps of:

21. The method for forming an integrated circuit according to claim 20, wherein the first local interconnect electrode comprises part of the charge storage capacitor.

22. The method for forming an integrated circuit according to claim 17, wherein the first ferroelectric layer and the first encapsulation layer form a dielectric layer of the charge storage capacitor.