REPLACEMENT GATE STRUCTURES FOR SEMICONDUCTOR DEVICES
The present disclosure is generally directed to various replacement gate structures for semiconductor devices. One illustrative gate structure disclosed herein includes, among other things, a gate insulation layer and a layer of gate electrode material with a substantially horizontal portion having a first thickness and a substantially vertical portion having a second thickness that is less than the first thickness. Furthermore, the substantially horizontal portion of the layer of gate electrode material is positioned adjacent to a bottom of the replacement gate structure and above at least a portion of the gate insulation layer, and the substantially vertical portion is positioned adjacent to sidewalls of the replacement gate structure.
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This is a continuation of co-pending application Ser. No. 13/445,547, filed Apr. 12, 2012.
BACKGROUND OF THE INVENTION1. Field of the Invention
Generally, the present disclosure relates to sophisticated semiconductor devices, and, more specifically, to replacement gate structures for semiconductor devices.
2. Description of the Related Art
The fabrication of advanced integrated circuits, such as CPU's, storage devices, ASIC's (application specific integrated circuits) and the like, requires the formation of a large number of circuit elements in a given chip area according to a specified circuit layout, wherein field effect transistors (NFET and PFET transistors) represent one important type of circuit element used in manufacturing such integrated circuit devices. A field effect transistor, irrespective of whether an NFET transistor or a PFET transistor is considered, typically comprises doped source and drain regions that are formed in a semiconducting substrate that are separated by a channel region. A gate insulation layer is positioned above the channel region and a conductive gate electrode is positioned above the gate insulation layer. By applying an appropriate voltage to the gate electrode, the channel region becomes conductive and current is allowed to flow from the source region to the drain region.
For many early device technology generations, the gate electrode structures of most transistor elements have comprised a plurality of silicon-based materials, such as a silicon dioxide and/or silicon oxynitride gate insulation layer, in combination with a polysilicon gate electrode. However, as the channel length of aggressively scaled transistor elements has become increasingly smaller, many newer generation devices employ gate electrode stacks comprising alternative materials in an effort to avoid the short channel effects which may be associated with the use of traditional silicon-based materials in reduced channel length transistors. For example, in some aggressively scaled transistor elements, which may have channel lengths on the order of approximately 14-32 nm, gate electrode stacks comprising a so-called high-k dielectric/metal gate (HK/MG) configuration have been shown to provide significantly enhanced operational characteristics over the heretofore more commonly used silicon dioxide/polysilicon (SiO/poly) configurations. These metal gate electrode materials may include, for example, one or more layers of titanium (Ti), titanium nitride (TiN), titanium-aluminum (TiAl), aluminum (Al), aluminum nitride (AlN), tantalum (Ta), tantalum nitride (TaN), tantalum carbide (TaC), tantalum carbonitride (TaCN), tantalum silicon nitride (TaSiN), tantalum silicide (TaSi) and the like.
One well-known processing method that has been used for forming a transistor with a high-k/metal gate structure is the so-called “gate last” or “replacement gate” technique.
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As device dimensions have decreased, the size of the gate cavity 20 has also been reduced. For example, in current-day advanced devices, the size (critical dimension) of the gate cavity 20 may only be about 20-30 nm, and further reductions in the size of the gate cavity 20 are anticipated as newer generations of devices are introduced. Thus, reliably filling such small-size gate cavities 20 with the various materials that are used to form the replacement gate structure 30 is becoming more challenging. Additionally, in some applications, plasma-based deposition processes, such as plasma-enhanced physical vapor deposition (PEPVD) or plasma-enhanced chemical vapor deposition (PECVD) processes are performed to form one or more of the layers of material that will become part of the replacement gate structure. However, the use of such plasma-based processes can have detrimental effects on other portions of a transistor device, such as the gate insulation layer, the substrate itself, etc., due to ion bombardment during such plasma-based processes. In some cases, such plasma-induced damage may cause the final transistor device to operate at reduced performance levels.
The present disclosure is directed to various, more efficient methods of forming replacement gate structures for semiconductor devices that may at least reduce or eliminate one or more of the problems identified above.
SUMMARY OF THE INVENTIONThe following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an exhaustive overview of the invention. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.
In general, the presently disclosed subject matter is directed to various replacement gate structures for semiconductor devices. One illustrative gate structure disclosed herein includes, among other things, a gate insulation layer and a layer of gate electrode material with a substantially horizontal portion having a first thickness and a substantially vertical portion having a second thickness that is less than the first thickness. Furthermore, the substantially horizontal portion of the layer of gate electrode material is positioned adjacent to a bottom of the replacement gate structure and above at least a portion of the gate insulation layer, and the substantially vertical portion is positioned adjacent to sidewalls of the replacement gate structure.
In another exemplary embodiment, a replacement metal gate structure of a transistor device is disclosed that includes a gate insulation layer that is made up of, among other things, a high-k dielectric material. Furthermore, the gate insulation layer has a substantially horizontal portion positioned above a channel region of the transistor device and a substantially vertical portion positioned along sidewalls of the replacement metal gate structure. The disclosed replacement metal gate structure further includes a first metal layer having a substantially horizontal portion positioned above the substantially horizontal portion of the gate insulation layer and a substantially vertical portion positioned adjacent to the substantially vertical portion of the gate insulation layer, wherein a thickness of the substantially vertical portion of the first metal layer is less than or equal to approximately one-half of a thickness of the substantially horizontal portion of the first metal layer. Moreover, the illustrative replacement metal gate structure also includes, among other things, a conductive metal gate electrode fill material positioned above the substantially horizontal portion of the first metal layer and adjacent to the substantially vertical portion of the first metal layer.
The disclosure may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:
While the subject matter disclosed herein is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
DETAILED DESCRIPTIONVarious illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
The present subject matter will now be described with reference to the attached figures. Various structures, systems and devices are schematically depicted in the drawings for purposes of explanation only and so as to not obscure the present disclosure with details that are well known to those skilled in the art. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the present disclosure. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.
The present disclosure is directed to various methods of forming replacement gate structures for semiconductor devices using a novel etching protocol. As will be readily apparent to those skilled in the art upon a complete reading of the present application, the various methods disclosed herein may be employed with a variety of technologies, e.g., NFET, PFET, CMOS, etc., and they may be readily employed in manufacturing a variety of integrated circuit devices, including, but not limited to, ASICs, logic devices, memory devices, etc. With reference to
After the gate cavity 220 is formed by removing the sacrificial gate structure, the various layers of material that will constitute a replacement gate structure 230 are formed in the gate cavity 220. As shown in
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The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the process steps set forth above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.
Claims
1.-22. (canceled)
23. A replacement gate structure, comprising:
- a gate insulation layer; and
- a layer of gate electrode material comprising a substantially horizontal portion having a first thickness and a substantially vertical portion having a second thickness that is less than said first thickness, wherein said substantially horizontal portion is positioned adjacent to a bottom of said replacement gate structure and above at least a portion of said gate insulation layer, and wherein said substantially vertical portion is positioned adjacent to sidewalls of said replacement gate structure.
24. The replacement gate structure of claim 23, wherein said second thickness is equal to or less than approximately one-half of said first thickness.
25. The replacement gate structure of claim 23, wherein said first thickness is approximately 4-5 nm and said second thickness is approximately 1-2 nm.
26. The replacement gate structure of claim 23, wherein said layer of gate electrode material comprises a first metal layer and a second metal layer formed on said first metal layer.
27. The replacement gate structure of claim 26, wherein a thickness of a substantially horizontal portion of said first metal layer is greater than a thickness of a substantially vertical portion of said first metal layer and a thickness of a substantially horizontal portion of said second metal layer is greater than a thickness of a substantially vertical portion of said second metal layer.
28. The replacement gate structure of claim 23, further comprising a conductive fill material positioned above said substantially horizontal portion of said layer of gate electrode material and adjacent to said substantially vertical portion of said layer of gate electrode material.
29. The replacement gate structure of claim 28, wherein said conductive fill material comprises at least one of copper, aluminum and titanium.
30. The replacement gate structure of claim 23, wherein said gate insulation layer comprises a substantially vertical portion that is positioned adjacent to said substantially vertical portion of said layer of gate electrode material.
31. The replacement gate structure of claim 23, wherein said gate insulation layer comprises a high-k dielectric material having a dielectric constant greater than approximately 10.
32. The replacement gate structure of claim 31, wherein said high-k dielectric material comprises at least one of tantalum oxide (Ta2O5), hafnium oxide (HfO2), zirconium oxide (ZrO2), titanium oxide (TiO2), aluminum oxide (Al2O3), and hafnium silicate (HfSiOx).
33. The replacement gate structure of claim 23, wherein said layer of gate electrode material comprises a work function adjusting metal layer.
34. The replacement gate structure of claim 33, wherein said work function adjusting metal layer comprises at least one of titanium (Ti), titanium-nitride (TiN), titanium-aluminum (TiAl), aluminum (Al), aluminum nitride (AlN), tantalum (Ta), tantalum nitride (TaN), tantalum carbide (TaC), tantalum carbonitride (TaCN), tantalum silicon nitride (TaSiN) and tantalum silicide (TaSi).
35. A replacement metal gate structure of a transistor device, the replacement metal gate structure comprising:
- a gate insulation layer comprising a high-k dielectric material, said gate insulation layer comprising a substantially horizontal portion positioned above a channel region of said transistor device and a substantially vertical portion positioned along sidewalls of said replacement metal gate structure;
- a first metal layer comprising a substantially horizontal portion positioned above said substantially horizontal portion of said gate insulation layer and a substantially vertical portion positioned adjacent to said substantially vertical portion of said gate insulation layer, wherein a thickness of said substantially vertical portion of said first metal layer is less than or equal to approximately one-half of a thickness of said substantially horizontal portion of said first metal layer; and
- a conductive metal gate electrode fill material positioned above said substantially horizontal portion of said first metal layer and adjacent to said substantially vertical portion of said first metal layer.
36. The replacement metal gate structure of claim 35, wherein said first metal layer comprises a work function adjusting material layer.
37. The replacement metal gate structure of claim 35, wherein said thickness of said substantially vertical portion of said first metal layer is approximately 1-2 nm.
38. The replacement metal gate structure of claim 35, further comprising a second metal layer positioned on said first metal layer.
39. The replacement metal gate structure of claim 38, wherein said second metal layer comprises a substantially horizontal portion having a first layer thickness and a substantially vertical portion having a second layer thickness that is less than said first layer thickness.
40. The replacement metal gate structure of claim 39, wherein said second layer thickness is less than approximately one-half of said first layer thickness.
41. The replacement metal gate structure of claim 35, wherein said conductive metal gate electrode fill material comprises one of copper, titanium and aluminum.
Type: Application
Filed: Jan 18, 2013
Publication Date: Oct 17, 2013
Applicant: GLOBALFOUNDRIES INC. (Grand Cayman)
Inventors: Dina Triyoso (Dresden), Hao Zhang (Dresden)
Application Number: 13/744,601
International Classification: H01L 29/78 (20060101);