Patent Application
20080087635
Example embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.
Various example embodiments will now be described more fully with reference to the accompanying drawings in which some example embodiments are shown. In the drawings, the thicknesses of layers and regions may be exaggerated for clarity.
Detailed illustrative embodiments are disclosed herein. However, specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments. This invention may, however, may be embodied in many alternate forms and should not be construed as limited to only the example embodiments set forth herein.
Accordingly, while the example embodiments are capable of various modifications and alternative forms, embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit example embodiments to the particular forms disclosed, but on the contrary, the example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of the invention. Like numbers refer to like elements throughout the description of the figures.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.).
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the scope of the example embodiments.
Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or a relationship between a feature and another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the Figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, for example, the term “below” can encompass both an orientation which is above as well as below. The device may be otherwise oriented (rotated 90 degrees or viewed or referenced at other orientations) and the spatially relative descriptors used herein should be interpreted accordingly.
Example embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, may be expected. Thus, example embodiments should not be construed as limited to the particular shapes of regions illustrated herein but may include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle may have rounded or curved features and/or a gradient (e.g., of implant concentration) at its edges rather than an abrupt change from an implanted region to a non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation may take place. Thus, the regions illustrated in the figures are schematic in nature and their shapes do not necessarily illustrate the actual shape of a region of a device and do not limit the scope.
It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In order to more specifically describe example embodiments, various aspects will be described in detail with reference to the attached drawings. However, the present invention is not limited to the example embodiments described.
Example embodiments relate to a method of etching a nickel (Ni) oxide layer used as a variable resistance layer of a resistive memory. Other example embodiments provide a method of manufacturing a storage node in a resistive memory in which a nickel oxide layer is used as a variable resistance layer.
A method of etching a nickel oxide layer according to example embodiments will now be described with reference to
Referring to
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The etched nickel oxide layer 64′ is sequentially etched using a desired plasma etching process. In the plasma etching process, it is desirable to independently control the mixed ratio of a gas mixture used as an etch gas and/or a bias power applied to the substrate.
Referring to
The inductively coupled plasma etching apparatus 100 further includes a chamber 108 in which a plasma etching process is performed, a coil 110 mounted in an upper wall of the chamber 108 surrounding a space above the stage 102 in the chamber 108, and an optical emission spectrometer 112 for checking the progress of etching in the chamber 108.
Light, which is emitted through an optical window (not shown) provided on the chamber 108, is analyzed by the optical emission spectrometer 112. Etching data (i.e., the etching progress in the chamber 108 or the type of by-product produced during the etching process) may be obtained through the optical emission spectrometer 112.
A second RF matching unit 114 independently controls power applied to the coil 110 of the chamber 108. Although not shown in the drawing, the inductively coupled plasma etching apparatus 100 is designed such that helium (He) gas may flow inside the stage 102 so that the temperature of (or heat from) the chuck 104 may be more effectively transferred to the substrate loaded on the stage 102.
If the nickel oxide layer is etched in the inductively coupled plasma etching apparatus 100, then the first RF matching unit 106 applies a bias voltage of 300V or less. According to other example embodiments, the bias voltage may be approximately 100V-150V. The second RF matching unit 114 applies a source power of 1.5-kW or less to the coil 110. The source power may be 500 W-800 W.
Plasma including ions, radicals and electrons that are produced from a mixed etch gas, which is uniformly introduced into the chamber 108 and used for etching, is generated in an upper space P over the stage 102 by the bias voltage applied by the first RF matching unit 106 and the source power applied by the second RF matching unit 114 or a combination thereof.
The nickel oxide layer 64 is etched by loading the substrate 60 with the mask pattern 65 formed on the nickel oxide layer 64 (interchangeably referred to as “resultant product 61” as shown in
An etching characteristic of the nickel oxide layer may be optimized (or increased) by varying factors such as a mixed ratio of the mixed etching gas, the main power applied to the inductively coupled plasma etching apparatus 100 to induce discharge of the mixed etching gas, the bias power applied to the substrate loaded on the stage 102, the substrate temperature, the process pressure, the gas flow rate, etc.
The nickel oxide layer may be more effectively etched if the mixed etching gas includes 40% to 70% of Cl2 gas. The main gas of the mixed etching gas may be BCl3, BBr3, HBr, CF4, C2F6, C4F8, CHF3, CO, Cl2 and mixtures thereof.
If the mixed etching gas is sprayed in the upper space P over the resultant product 116 by the nozzle (not shown) mounted on the chamber 108, a desired source power (e.g., 500 W) may be applied to the inductively coupled plasma etching apparatus 100. As such, radicals and ions plasma (that may be used for etching) may be produced from the mixed etching gas. The nickel oxide layer 64 around the mask pattern 65 of the resultant product 116 may be etched by the plasma. After the nickel oxide layer 64 around the mask pattern 65 is etched, the mask pattern 65 is removed.
If the inductively coupled plasma etching apparatus 100 and the mixed etching gas having the mixed ratio are used to etch the nickel oxide layer, the plasma density increases. In other words, the density of the radicals and ions participating in the etching reaction increases. As such, the plasma is further activated and a by-product produced during the etching process performed at a temperature of 100° C. or less, more desirably at room temperature of approximately 25° C., has a higher volatility.
As described above, because the etching process for forming the nickel oxide layer 64 is performed by a low temperature process of 25° C. to 100° C., opposed to a conventional high temperature process (e.g., a few hundred degrees Celsius), thermal damage to the nickel oxide layer 64 in the etching process may be prevented (or reduced). As described above, because the etch by-product produced using the low temperature process has a higher volatility, the re-deposition of the etch by-product on the etched nickel oxide layer 64 is prevented (or reduced), increasing the profile of the nickel oxide layer 64 in comparison to the conventional art.
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A method of manufacturing a storage node of a resistive memory according to example embodiments will now be described with reference to
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The upper electrode layer 86, the nickel oxide layer 84 and the lower electrode layer 82 are sequentially etched using the inductively coupled plasma etching apparatus 100 of
The etching characteristics of the upper electrode layer 86, the nickel oxide layer 84 and the lower electrode layer 82 may be increased by optimizing factors such as a mixed ratio of the mixed etching gas, the main power applied to the inductively coupled plasma etching apparatus 100 to induce discharge of the mixed etching gas, the bias power applied to the substrate loaded on the stage 102, the substrate temperature, the process pressure, the gas flow rate, etc.
The mixed etching gas may include Cl2 gas as a main gas and an additive gas (e.g., argon (Ar) gas). The nickel oxide layer 84 is more effectively etched if the mixed etching gas includes 40% to 70% of Cl2 gas. The main gas may include BCl3, BBr3, HBr, CF4, C2F6, C4F8, CHF3, CO, Cl2, and mixtures thereof.
After the upper electrode layer 86, the nickel oxide layer 84, and the lower electrode layer 82 around the mask pattern 87 are etched, the mask pattern 87 may be removed.
As described above, because the etching process for forming the nickel oxide layer 84 is performed using a low temperature process at room temperature (i.e., approximately 25° C.), opposed to a high temperature process (i.e., a few hundred degrees Celsius), thermal damage to the nickel oxide layer 84 in the etching process may be prevented or reduced. Because the etch by-product produced in the low temperature process has higher volatility, the re-deposition of the etch by-product on the etched nickel oxide layer 84 is prevented (or reduced), increasing the profile of the nickel oxide layer 84 in comparison to the conventional art.
As described above, an etch method of a nickel oxide layer according example embodiments is performed in an inductively coupled plasma etching apparatus. As the etching begins, a mixed etching gas, in which Cl2 gas and Ar gas are mixed in an optimum ratio, is uniformly supplied to the inductively coupled plasma etching apparatus to generate plasma for etching. The density of the plasma (i.e., radicals and ions that participate in the etching process) increases in the inductively coupled plasma etching apparatus. As such, the etching process may be performed at a temperature lower than 100° C. (e.g., at approximately 25° C.). Thermal damage to the nickel oxide layer in the etching process may be prevented or reduced.
Because the plasma is more highly activated in comparison to the conventional art, an etch by-product produced by the etching process has higher volatility. The etch by-product is not re-deposited on the storage node due to the higher volatility of the etch by-product. As such, the storage node has a smoother side surface and a slope close to 90-degrees, increasing the profile of storage node in comparison to the conventional art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0101047 | Oct 2006 | KR | national |
