CAPACITOR STRUCTURE
A DRAM capacitor structure is disposed on the interior surface of a vertical hollow cylinder of a support structure overlying a semiconductor substrate. The support structure further includes a horizontal supporting layer that is integrally connected with the vertical hollow cylinder. A fabrication method for forming the DRAM capacitor structure is also provided.
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This is a continuation application of U.S. application Ser. No. 13/085,493 filed Apr. 13, 2011, which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a capacitor structure and a fabrication method thereof, and more particularly, to a dynamic random access memory stack capacitor structure having a particular supporting structure and a fabrication method thereof.
2. Description of the Prior Art
A dynamic random access memory (DRAM) device is made up of many memory cells. Generally, the memory cell is a semiconductor memory device with an access transistor and a storage capacitor. Each memory cell can store one bit of data by storing electric charges in the storage capacitor.
In general, the storage capacitor contains an upper electrode, a dielectric layer, and a lower electrode. The storage capability of the storage capacitor is proportional to an overlapping area between the upper/lower electrodes and the dielectric layer. Since modern electrical products are developed with minimized sizes thereof, the area of each memory cell tends to be reduced, so that the DRAM device can be designed with high integrated density. However, the reduction of the area of each memory cell leads to lower storage capability of the memory cell, which requires high refresh frequency and therefore affects the performance of the DRAM device. Currently, two methods are provided to increase storage capability of the storage capacitor. A method is proposed to use a material with higher dielectric constant for the dielectric layer, and the other method is proposed to increase the overlapping area between the upper/lower electrodes and the dielectric layer.
Several methods of increasing the area of the capacitor electrode have been proposed in the prior art. For example, crown-type stacked capacitors can be used to increase the total surface area of the capacitor electrode owing to its sidewall structures. According to the prior art, lithography and etching process is performed to form a plurality of crown-type stacked capacitors, and each crown-type stacked capacitor is supported by a supporting structure. However, the existing supporting structures are only formed at a top of each crown-type stacked capacitor and tend to be damaged, which may cause a reduction of product yield. Therefore, a capacitor structure having a particular supporting structure and a fabrication method thereof are required.
SUMMARY OF THE INVENTIONIt is therefore one of the objectives of the present invention to provide a capacitor structure with a particular supporting structure and a fabrication method thereof, in which storage capacitors can be well supported.
In accordance with the present invention, a capacitor structure is disposed on an interior surface of a vertical hollow cylinder of a supporting structure. The supporting structure is disposed on a substrate, and the supporting structure further includes a horizontal supporting layer connected to the vertical hollow cylinder.
A fabrication method of the capacitor structure is also provided. A substrate is provided, and at least one capacitor disposing region is defined on the substrate. A supporting region is defined on a portion of the substrate where no capacitor disposing region is located. Then, a supporting structure is formed on the substrate, where the supporting structure includes at least one vertical hollow cylinder and a horizontal supporting layer connected to the vertical hollow cylinder. Each vertical hollow cylinder surrounds the corresponding capacitor disposing region, and the supporting layer is disposed on the substrate within the supporting region. Finally, a capacitor structure is formed in the vertical hollow cylinder.
In the present invention, the storage capacitor is not only disposed on an exterior surface of the capacitor structure, but also entirely supports sidewalls of the capacitor structure. Thus, product yield of the storage capacitor can be promoted.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
To provide a better understanding of the presented invention for one skilled in the art, preferred embodiments will be detailed as follows. The preferred embodiments of the present invention are illustrated in the accompanying drawings with numbered elements to elaborate the contents and effects to be achieved.
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It can be seen from the aforementioned descriptions that a capacitor structure and a fabrication method thereof are provided in the present invention. The storage capacitor of the present invention has particular supporting structure, and therefore is not only disposed on the exterior surface of each capacitor structure, but also entirely supports sidewalls of each capacitor structure. Thus, the product yield of the storage capacitor can be promoted. In accordance with an embodiment, the supporting structure includes a carbon layer with electrical neutrality, which provides preferable supporting strength. In accordance with another embodiment, the low-k dielectric layer disposed in the storage capacitor can reduce the capacitive coupling effect between the metal layer and the capacitor structure. Additionally, according to conventional method of fabricating storage capacitor, a plurality of concavities are formed in advance, and then the capacitor structures are formed in the concavities. In the present invention, a plurality of sacrificial cylinders are formed in advance, and then the supporting structure and the capacitor structures are formed by utilizing the sacrificial cylinders. The sacrificial cylinders are formed by a negative photoresist layer with a mask (please refer to
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Claims
1. A capacitor structure, characterized in that:
- the capacitor structure is disposed on an interior surface of a vertical hollow cylinder of a supporting structure, wherein the supporting structure is disposed on a substrate, and the supporting structure further includes a horizontal supporting layer connected to a bottom end of the vertical hollow cylinder, and the capacitor structure is constituted by a first conductive layer disposed on at least an interior surface of the vertical hollow cylinder, a capacitor dielectric layer disposed on a surface of the first conductive layer, and a second conductive layer disposed on a surface of the capacitor dielectric layer.
2. The capacitor structure according to claim 1, wherein a central axis of the vertical hollow cylinder is substantially perpendicular to a horizontal plane of the substrate.
3. The capacitor structure according to claim 1, wherein the vertical hollow cylinder surrounds a capacitor disposing region, the supporting layer is disposed on a portion of the substrate where no capacitor disposing region is located, and a bottom of the vertical hollow cylinder is connected to the horizontal supporting layer.
4. The capacitor structure according to claim 1, wherein the first conductive layer is further disposed on an exterior surface of the vertical hollow cylinder and an upper surface of the horizontal supporting layer.
5. The capacitor structure according to claim 1, wherein the first conductive layer disposed on the interior surface of the vertical hollow cylinder is electrically insulated from the first conductive layer disposed on the exterior surface of the vertical hollow cylinder.
6. The capacitor structure according to claim 1, wherein the supporting structure comprises a carbon layer.
7. The capacitor structure according to claim 1, further comprising:
- a dielectric layer, disposed on the supporting structure and the capacitor structure; and
- a conductive layer, disposed on the dielectric layer, wherein the conductive layer is electrically connected to each capacitor structure.
8. The capacitor structure according to claim 7, wherein a thickness of the dielectric layer is substantially smaller than a height of the capacitor structure.
9. The capacitor structure according to claim 7, wherein the dielectric layer includes undoped silicate glass, borophosphosilicate glass, fluorine-doped silicate glass, hydrogen silsesquioxane (Si:OH), methyl silsesquioxane (SiO:CH3), hydropolysilsesquioxane, methyl polysilsesquioxane or phenyl polysilsesquioxane.
10. The capacitor structure according to claim 1, wherein the vertical hollow cylinder and the horizontal supporting layer are made of the same material.
Type: Application
Filed: Dec 4, 2013
Publication Date: Mar 27, 2014
Applicant: INOTERA MEMORIES, INC. (Taoyuan)
Inventors: Tah-Te Shih (Taipei), Tsung-Cheng Yang (Taichung City)
Application Number: 14/097,225
International Classification: H01L 49/02 (20060101); H01L 27/108 (20060101);