A method of forming a capacitor on a semiconductor wafer includes: a) in a dry etching reactor, selectively anisotropically dry etching a capacitor contact opening having a minimum selected open dimension into an insulating dielectric layer utilizing selected gas flow rates of a reactive gas component and an inert gas bombarding component, the flow rate of the bombarding component significantly exceeding the flow rate of the reactive component to effectively produce a capacitor contact opening having grooved striated sidewalls and thereby defining female capacitor contact opening striations; b) providing a layer of an electrically conductive storage node material within the striated capacitor contact opening; c) removing at least a portion of the conductive material layer to define an isolated capacitor storage node within the insulating dielectric having striated sidewalls; d) etching the insulating dielectric layer selectively relative to the conductive material sufficiently to expose at least a portion of the external male striated conductive material sidewalls; and e) providing conformal layers of capacitor dielectric and capacitor cell material atop the etched conductive material and over its exposed striated sidewalls. The invention also includes a stacked capacitor construction having an electrically conductive storage node with upwardly rising external sidewalls. Such sidewalls have longitudinally extending striations to maximize surface area and corresponding capacitance in a resulting construction.
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1. A stacked capacitor construction formed within a semiconductor substrate comprising:
an electrically conductive storage node, the storage node having upwardly rising external sidewalls, the upwardly rising external sidewalls having longitudinally extending striations to maximize surface area and corresponding capacitance; a striated cell dielectric layer provided over the storage node and its associated longitudinally extending striations; and an electrically conductive striated cell layer provided over the striated cell dielectric layer.
0. 68. A stacked capacitor construction formed within a semiconductor substrate comprising:
an electrically conductive storage node, the storage node having external sidewalls, the external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external sidewalls including striations; a dielectric layer provided over the storage node and its associated external sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the surface of the electrically conductive layer including partial striations.
0. 66. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein; an electrically conductive storage node, the storage node having external sidewalls, the external sidewalls each having a texturized surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external side walls including striations; a dielectric layer provided over the storage node and its associated external sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the surface of the electrically conductive layer including partial striations.
0. 67. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein; an electrically conductive storage node, the storage node having external sidewalls, the external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external side walls including striations; a dielectric layer provided over the storage node and its associated external sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, a portion of the surface of the electrically conductive layer including partial striations.
0. 29. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having a grooved striated sidewall; an electrically conductive storage node, the storage node having external sidewalls, the external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external sidewalls including striations; a dielectric layer provided over the storage node and its associated external sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the electrically conductive layer including striations.
0. 65. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein; an electrically conductive storage node formed within the at least one contact opening, the storage node having external sidewalls, the external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external sidewalls including striations; a dielectric layer provided over the storage node and its associated external sidewalls, the dielectric layer including striations; and an electrically conductive cell layer provided over the cell dielectric layer, the electrically conductive cell layer including striations.
0. 17. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having a pretexturized striated sidewall; an electrically conductive storage node, the storage node having external sidewalls, the external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external sidewalls including striated sidewalls; a dielectric layer provided over the storage node and its associated external sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the electrically conductive layer including striations.
0. 53. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having striations in the sidewall; an electrically conductive storage node, the storage node having external sidewalls, the external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external side walls including striations; a dielectric layer provided over the storage node and its associated external sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the surface of the electrically conductive layer including partial striations.
0. 21. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having a pretexturized striated sidewall; an electrically conductive storage node, the storage node having rising external sidewalls, the rising external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external sidewalls including striations; a dielectric layer provided over the storage node and its associated rising external sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the electrically conductive layer including striations.
0. 33. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having a grooved striated sidewall; an electrically conductive storage node, the storage node having rising external sidewalls, the rising external sidewalls each having a surface thereon including to maximize surface area and corresponding capacitance, the surfaces of the external sidewalls including striations; a dielectric layer provided over the storage node and its associated rising external sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the electrically conductive layer including striations.
0. 57. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having striations in the sidewall; an electrically conductive storage node, the storage node having raised external sidewalls, the raised external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the raised external sidewalls including striations; a dielectric layer provided over the storage node and its associated raised external sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the surface of the electrically conductive layer including partial striations.
0. 13. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having a striated sidewall; an electrically conductive storage node, the storage node having upwardly rising external sidewalls, the upwardly rising external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external sidewalls including striations; a dielectric layer provided over the storage node and its associated upwardly rising sidewalls, the cell dielectric layer including striations; and an electrically conductive cell layer provided over the cell dielectric layer, the electrically conductive cell layer including striations.
0. 5. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having a striated sidewall; an electrically conductive storage node formed within the at least one contact opening the storage node having external sidewalls, the external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external sidewalls including striations; a dielectric layer provided over the storage node and its associated external sidewalls, the dielectric layer including striations; and an electrically conductive cell layer provided over the cell dielectric layer, the electrically conductive cell layer including striations.
0. 25. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having a pretexturized striated sidewall; an electrically conductive storage node, the storage node having upwardly rising external sidewalls, the upwardly rising external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external sidewalls including striations; a dielectric layer provided over the storage node and its associated upwardly rising external sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the electrically conductive layer including striations.
0. 37. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having a grooved striated sidewall; an electrically conductive storage node, the storage node having upwardly rising external sidewalls, the upwardly rising external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the upwardly rising external sidewalls including striations; a dielectric layer provided over the storage node and its associated upwardly rising sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the electrically conductive layer including striations.
0. 9. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having a striated sidewall; an electrically conductive storage node formed within the at least one contact opening, the storage node having rising external sidewalls, the rising external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the rising external sidewalls including striations; a dielectric layer provided over the storage node and its associated rising external sidewalls, the dielectric layer including striations; and an electrically conductive cell layer provided over the cell dielectric layer, the electrically conductive cell layer including striations.
0. 61. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having striations in the sidewall; an electrically conductive storage node, the storage node having upwardly raised external sidewalls, the upwardly raised external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the upwardly raised external sidewalls including striations; a dielectric layer provided over the storage node and its associated upwardly raising external sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the surface of the electrically conductive layer including partial striations.
0. 41. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having striations in the sidewall; an electrically conductive storage node, the storage node having external sidewalls, the external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external sidewalls including complementary striations therein to the striations in the sidewall of the at least one contact opening of the layer of insulating dielectric material; a dielectric layer provided over the storage node and its associated external sidewalls; and an electrically conductive layer provided over the dielectric layer, the electrically conductive layer including striations.
0. 45. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having striations in the sidewall; an electrically conductive storage node, the storage node having rising external sidewalls, the rising external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the rising external sidewalls including complementary striations therein to the striations in the sidewall of the at least one contact opening of the layer of insulating dielectric material; a dielectric layer provided over the storage node and its associated rising external surfaces, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the electrically conductive layer including striations.
0. 49. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having striations in the sidewall; an electrically conductive storage node, the storage node having upwardly rising external sidewalls, the upwardly rising external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the upwardly rising external sidewalls including complementary striations therein to the striations in the sidewall of the at least one contact opening of the layer of insulating dielectric material; a dielectric layer provided over the storage node and its associated upwardly rising external surfaces, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the electrically conductive layer including striations.
0. 72. A stacked capacitor construction formed within a semiconductor substrate comprising:
a layer of insulating dielectric material located on the semiconductor substrate having at least one contact opening therein, the contact opening having a minimum selected open contact dimension; an electrically conductive storage node, the storage node having external sidewalls, the external sidewalls each having a surface thereon to maximize surface area and corresponding capacitance, the surfaces of the external sidewalls including striations, the electrically conductive storage node having a thickness, the thickness less than about 30 % of the minimum selected open contact dimension of the contact opening in the layer of insulating dielectric material; a dielectric layer provided over the storage node and its associated external sidewalls, the dielectric layer including striations; and an electrically conductive layer provided over the dielectric layer, the surface of the electrically conductive layer including partial striations.
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This patent resulted from a divisional application of U.S. patent application Ser. No. 07/854,435, filed Mar. 18, 1992, which is now U.S. Pat. No. 5,238,862.
This invention relates generally to three dimensional sack capacitors and the fabrication thereof.
As DRAMs increase in memory cell density, there is a continuous challenge to maintain sufficiently high storage capacitance despite decreasing cell area A principal way of increasing cell capacitance is through cell structure techniques. Such techniques include three dimensional cell capacitors such as trenched or stacked capacitors. This invention concerns stacked capacitor cell constructions.
With the conventional stacked capacitor, the capacitor is formed immediately above and electrically connected to the active device area of the associated MOS transistor of the memory cell. Typically, only the upper surface of the lower storage polysilicon node of the capacitor is utilized for capacitance. However, some attempts have been made to provide constructions to increase capacitance, whereby the back side of one capacitor terminal is used to store charge. Such is shown by way of example by T. Ema et al. "3-Dimensional Stacked Capacitor Cell For 16M and 64M DRAMS", IEDM Tech. Digest, pp. 592, 595, 1988 and S. Inoue et al., "A Spread Stacked Capacitor (SSC) Cell For 64 MBit DRAMs", IEDM Tech. Digest, pp. 31-34, 1989.
One standard prior art technique for forming a stacked "crown" cell capacitor is described with reference to
Referring to
Referring to
It is an object of this invention to enable such and similar stacked capacitor constructions to have increased capacitance.
Preferred embodiments of the invention are described below with reference to the following accompanying drawings.
This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws "to promote the progress of science and useful arts" (Article 1, Section 8).
In accordance with one aspect of the invention, a method of forming a capacitor on a semiconductor wafer comprises the following steps:
providing a layer of insulating dielectric atop a semiconductor wafer to a selected thickness;
in a dry etching reactor, selectively anisotropically dry etching a capacitor contact opening having a minimum selected open dimension into the insulating dielectric layer utilizing selected gas flow rates of a reactive gas component and an inert gas bombarding component, the flow rate of the bombarding component significantly exceeding the flow rate of the reactive component to effectively produce a capacitor contact opening having grooved striated sidewalls and thereby defining female capacitor contact opening striations;
providing a layer of electrically conductive material atop the wafer and within the striated capacitor contact opening to a selected thickness which is less than the selected open dimension, the electrically conductive material filling the grooved striations of the capacitor contact opening thereby defining striated external conductive material sidewalls within the capacitor contact opening which are male complementary its shape to the female capacitor contact opening striations;
removing at least a portion of the conductive material layer to define an isolated capacitor storage node within the insulating dielectric;
etching the insulating dielectric layer selectively relative to the conductive material sufficiently to expose at least a portion of the external male striated conductive material sidewalls;
providing a conformal capacitor dielectric layer atop the etched conductive material and over its exposed striated sidewalls; and
providing a conformal capacitor cell layer of electrically conductive material atop the capacitor dielectric layer.
In accordance with another aspect of the invention, a stacked capacitor construction formed within a semiconductor substrate comprises:
an electrically conductive storage node, the storage node having upwardly rising external sidewalls, the upwardly rising external sidewalls having longitudinally extending striations to maximize surface area and corresponding capacitance;
a striated cell dielectric layer provided over the storage node and its associated longitudinally extending striations; and
an electrically conductive striated cell layer provided over the striated cell dielectric layer.
More particularly and with reference to the figures,
More specifically, contact opening 54 results from a selective anisotropic dry etch in a dry etching reactor to produce a minimum selected open dimension "A" into insulating dielectric layer 52. A wider open dimension "C" for contact opening 54 results from the elliptical shape. Such etching is conducted utilizing selected gas flow rates of a reactive gas component and an inert gas bombarding component. The flow rate of the bombarding component significantly and effectively exceeds the flow rate of the reactive component to produce capacitor contact opening 54 having grooved striated sidewalls 56. As illustrated, striated sidewalls have peak ridges 55 and low valleys 57, which define (for purposes of continuing discussion) female capacitor contact opening striations 58. Effective excess flow of an inert gas bombarding component, as compared to the reactive gas component, has been determined to enable controllable production of the illustrated striations.
The bombarding gas component is preferably selected from the group consisting of argon, krypton and xenon or mixtures thereof. The invention was reduced to practice utilizing argon. The reactive gas component need be reactive with the insulating material of layer 52. Where such layer comprises SiO2, reactive gas components of CF4 and CHF3 would be operable. Preferably, the flow rate to the reactor of the bombarding gas component is sufficient to produce a partial pressure of bombarding gas within the reactor of greater than or equal to about 31 mTorr.
Argon, CF4and CF3 are known prior art components for etching smooth-walled contact openings through SiO2 layers but not utilized in the manner claimed in this document For example, a conventional prior art process for etching a prior art contact opening 24 (
Referring to
Referring to
Referring to
Referring to
The above-described technique and construction increases contact sidewall surface area significantly over the prior art for maximization of capacitance for a given photo feature size. The prior art embodiment of
The intent is to maximize flow of the bombarding component, while minimizing total reactor pressure, and thereby increase the flow rate of argon relative to the reactive gas components. The invention functions by providing a pretexturized, striated surface before polysilicon is deposited to maximize surface area in both external and internal portions of the deposited polysilicon. The resultant product is improved over the prior art the result of increased capacitance.
In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.
Wald, Phillip G., Blalock, Guy
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