US20160071928A1

US20160071928A1 - Methods of forming gate structures for finfet devices and the resulting semiconductor products

Info

Publication number: US20160071928A1
Application number: US14/943,522
Authority: US
Inventors: Ruilong Xie; Shom Ponoth; Juntao Li
Original assignee: GlobalFoundries Inc; International Business Machines Corp
Current assignee: GlobalFoundries Inc; International Business Machines Corp
Priority date: 2013-08-21
Filing date: 2015-11-17
Publication date: 2016-03-10
Also published as: US20150054078A1; US9219153B2

Abstract

A transistor device includes first and second spaced-apart active regions positioned in a semiconductor substrate, each of the respective first and second spaced-apart active regions having at least one fin. First and second spaced-apart gate structures are positioned above the respective first and second active regions, each of the first and second gate structures having end surfaces. A gate separation structure is positioned between the first and second spaced-apart gate structures, wherein first and second opposing surfaces of the gate separation structure abut an entirety of the respective end surfaces of the first and second spaced-apart gate structures, and wherein an upper surface of the gate separation structure is positioned at a greater height level above the semiconductor substrate than an upper surface of the at least one fin of each of the respective first and second spaced-apart active regions.

Description

BACKGROUND

1. Field of the Disclosure
Generally, the present disclosure relates to the fabrication of integrated circuits, and, more particularly, to various methods of forming gate structures for FinFET devices and the resulting semiconductor devices.
2. Description of the Related Art
In modern integrated circuits, such as microprocessors, storage devices and the like, a very large number of circuit elements, especially transistors, are provided and operated on a restricted chip area. Immense progress has been made over recent decades with respect to increased performance and reduced feature sizes of circuit elements, such as transistors. However, the ongoing demand for enhanced functionality of electronic devices forces semiconductor manufacturers to steadily reduce the dimensions of the circuit elements and to increase the operating speed of the circuit elements. The continuing scaling of feature sizes, however, involves great efforts in redesigning process techniques and developing new process strategies and tools so as to comply with new design rules. Generally, in complex circuitry including complex logic portions, MOS technology is presently a preferred manufacturing technique in view of device performance and/or power consumption and/or cost efficiency. In integrated circuits including logic portions fabricated by MOS technology, field effect transistors (FETs) are provided that are typically operated in a switched mode, that is, these devices exhibit a highly conductive state (on-state) and a high impedance state (off-state). The state of the field effect transistor is controlled by a gate electrode, which controls, upon application of an appropriate control voltage, the conductivity of a channel region formed between a drain region and a source region.
To improve the operating speed of FETs, and to increase the density of FETs on an integrated circuit device, device designers have greatly reduced the physical size of FETs over the years. More specifically, the channel length of FETs has been significantly decreased, which has resulted in improving the switching speed of FETs. However, decreasing the channel length of a FET also decreases the distance between the source region and the drain region. In some cases, this decrease in the separation between the source and the drain makes it difficult to efficiently inhibit the electrical potential of the source region and the channel from being adversely affected by the electrical potential of the drain. This is sometimes referred to as a so-called short channel effect, wherein the characteristic of the FET as an active switch is degraded.
In contrast to a FET, which has a planar structure, a so-called FinFET device has a three-dimensional (3D) structure. FIG. 1A is a perspective view of an illustrative prior art FinFET semiconductor device “A” that is formed above a semiconductor substrate B that will be referenced so as to explain, at a very high level, some basic features of a FinFET device. In this example, the FinFET device A includes three illustrative fins C, a gate structure D, sidewall spacers E and a gate cap layer F. The gate structure D is typically comprised of a layer of insulating material (not separately shown), e.g., a layer of high-k insulating material or silicon dioxide, and one or more conductive material layers (e.g., metal and/or polysilicon) that serve as the gate electrode for the device A. The fins C have a three-dimensional configuration: a height H, a width W and an axial length L. The axial length L corresponds to the direction of current travel in the device A when it is operational. The portions of the fins C covered by the gate structure D are the channel regions of the FinFET device A. In a conventional process flow, the portions of the fins C that are positioned outside of the spacers E, i.e., in the source/drain regions of the device A, may be increased in size or even merged together (a situation not shown in FIG. 1A) by performing one or more epitaxial growth processes. The process of increasing the size of or merging the fins C in the source/drain regions of the device A is performed to reduce the resistance of source/drain regions and/or make it easier to establish electrical contact to the source/drain regions. Even if an epi “merger” process is not performed, an epi growth process will typically be performed on the fins C to increase their physical size.
In the FinFET device A, the gate structure D may enclose both sides and the upper surface of all or a portion of the fins C to form a tri-gate structure so as to use a channel having a three-dimensional structure instead of a planar structure. In some cases, an insulating cap layer (not shown), e.g., silicon nitride, is positioned at the top of the fins C and the FinFET device only has a dual-gate structure (sidewalls only). Unlike a planar FET, in a FinFET device, a channel is formed perpendicular to a surface of the semiconducting substrate so as to reduce the physical size of the semiconductor device. Also, in a FinFET, the junction capacitance at the drain region of the device is greatly reduced, which tends to significantly reduce short channel effects. When an appropriate voltage is applied to the gate electrode of a FinFET device, the surfaces (and the inner portion near the surface) of the fins C, i.e., the vertically oriented sidewalls and the top upper surface of the fin, form a surface inversion layer or a volume inversion layer that contributes to current conduction. In a FinFET device, the “channel-width” is estimated to be about two times (2×) the vertical fin-height plus the width of the top surface of the fin, i.e., the fin width. Multiple fins can be formed in the same foot-print as that of a planar transistor device. Accordingly, for a given plot space (or foot-print), FinFETs tend to be able to generate significantly higher drive current density than planar transistor devices. Additionally, the leakage current of FinFET devices after the device is turned “OFF” is significantly reduced as compared to the leakage current of planar FETs, due to the superior gate electrostatic control of the “fin” channel on FinFET devices. In short, the 3D structure of a FinFET device is a superior MOSFET structure as compared to that of a planar FET, especially in the 20 nm CMOS technology node and beyond. The gate structures D for such FinFET devices may be manufactured using so-called “gate-first” or “replacement gate” (gate-last) manufacturing techniques.
Over recent years, due to the reduced dimensions of the transistor devices, the operating speed of the circuit components has been increased with every new device generation, and the “packing density,” i.e., the number of transistor devices per unit area, in such products has also increased during that time. As a result of such increased packing densities, the physical space between adjacent devices has become very small, which can lead to some problems in manufacturing. FIGS. 1B-1E are plan views that depict the manufacture of eight separate FinFET devices above four separated active regions so as to explain one current problem encountered when attempting to manufacture FinFET devices in applications requiring very high packing densities.
FIG. 1B is a plan view of an illustrative prior art integrated circuit product 10 at an advanced stage of fabrication. In general, the product 10 is comprised of eight illustrative FinFET devices 11A-11H, wherein two of each of the FinFET devices are above each of four spaced-apart active regions 12A-12D that are defined in a semiconductor substrate by regions 18 of an isolation material, such as trenches filled with silicon dioxide. In the depicted example, the FinFET devices 11A-11H share a common source or drain region, see, e.g., the FinFET devices 11A, 11B wherein they each have separate drain regions (DR) but a common source region (SR). In this particular example, each of the FinFET devices 11A-11H is comprised of five illustrative fins 14 and an illustrative gate structure 16. A layer of insulating material 13 would have been formed between the fins 14 on active regions 12A-12D so as to locally isolate the fins 14 from one another. At this point in the process flow, the gate structures 16 would include sidewall spacers and a cap layer (each of which are not separately shown) so as to encapsulate and protect the gate electrode and gate insulation materials. In this particular example, the FinFET devices 11A-11D formed above the active regions 12A-12B share common gate electrodes, while the FinFET devices 11E-11H formed above the active regions 12C-12D are depicted as having separate gate electrode structures 16. The gate electrodes for the FinFET devices are typically formed by patterning one or more layers of material, i.e., the gate stack materials, to define long parallel line-type structures, i.e., gate electrode structures that extend across multiple active regions and multiple isolation regions. These long, line-type gate electrode structures are initially patterned so as to have the desired critical dimension (i.e., the dimension of gate electrode corresponding to the gate length of the finished device). That is, the sides 16Y of the line-type gate electrode structures 16 are patterned first. At some point later in the process flow, these long, line-type gate electrode structures are subsequently “cut” by performing an etching process to define the final gate electrodes. That is, the ends 16X of the line-type gate electrode structures 16 are patterned last so as to thereby define the final gate electrodes. The region 15 in FIG. 1B depicts the cuts made in the gate structures 16 formed above the active regions 12C-12D.
FIG. 1C depicts the product 100 after a selective epitaxial deposition process, i.e., a fin “merger” process, has been performed to form an epi semiconductor material 20 on the exposed portions of the fins 14. For reference purposes, the fins 14 formed above the active region 12A are depicted in dashed lines in FIG. 1C.
FIG. 1D depicts the product 100 after conductive contact structures 22 have been formed so as to establish electrical connection to the merged source/drain regions of the FinFET devices 11A-11H. The contact structures 22 would have been formed in contact openings formed in a previously formed layer of insulating material (not shown) that was formed above the source/drain regions. The contact structures 22 may be formed from a variety of materials, e.g., tungsten. In some cases, the contact structures 22 are referred to as “trench-silicide” structures due to the fact that they may be formed in trench-type openings and a metal silicide is formed where the contact 22 engages the epi semiconductor material 20.
FIG. 1E is an enlarged view of a portion of the product 100 shown in FIG. 1D. In general, the ends 16X of the gate structures 16 must be designed such that they extend a distance 16D beyond the edge of the active regions so as to prevent undesirable “bridging” of the epi material 20, as reflected by the dashed arrow 30. To the extent such bridging occurs, then device failure may occur due to the presence of a short between the source/drain regions of the FinFET device. In one example, using current day technology, the distance 16D (spacing between the end of electrode 16 and the sidewall of fin 14) may be on the order of about 30-50 nm, while the end-to-end spacing 16R between electrodes 16 may be on the order of about 30-50 nm. One solution to remedy the potential for bridging of the epi material formed on the fins 14 would be to simply make the distance 16D large enough so that there is little, if any, potential form the undesirable bridging of the epi material. However, such a “solution” would lead to reduced packing densities, which is counter to the ongoing trend in the industry now and for the foreseeable future.
The present disclosure is directed to various methods of forming gate structures for FinFET devices and the resulting semiconductor devices that may avoid, or at least reduce, the effects of one or more of the problems identified above.

SUMMARY OF THE DISCLOSURE

The following presents a simplified summary of the disclosure in order to provide a basic understanding of some aspects of the subject matter that is described in further detail below. This summary is not an exhaustive overview of the disclosure, nor is it intended to identify key or critical elements of the subject matter disclosed here. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.
Generally, the present disclosure is directed to methods of forming gate structures for FinFET devices and the resulting semiconductor devices. One illustrative transistor device disclosed herein includes, among other things, first and second spaced-apart active regions positioned in a semiconductor substrate, each of the respective first and second spaced-apart active regions having at least one fin. Furthermore, first and second spaced-apart gate structures are positioned above the respective first and second active regions, each of the first and second gate structures having end surfaces. Additionally, a gate separation structure is positioned between the first and second spaced-apart gate structures, wherein first and second opposing surfaces of the gate separation structure abut an entirety of the respective end surfaces of the first and second spaced-apart gate structures, and wherein an upper surface of the gate separation structure is positioned at a greater height level above the semiconductor substrate than an upper surface of the at least one fin of each of the respective first and second spaced-apart active regions.
Yet another illustrative transistor device of the present disclosure includes first and second spaced-apart active regions positioned in a semiconductor substrate, each of the respective first and second spaced-apart active regions having at least one fin. The exemplary transistor device further includes, among other things, first and second spaced-apart gate structures positioned above and extending across the at least one fin of each of the respective first and second spaced-apart active regions, each of the first and second spaced-apart gate structures having side surfaces, wherein the first gate structure is oriented parallel to the second gate structure. Furthermore, a gate separation structure is positioned between adjacent side surfaces of the first and second spaced-apart gate structures, wherein an upper surface of the gate separation structure is positioned at a greater height level above the semiconductor substrate than an upper surface of the at least one fin of each of the respective first and second spaced-apart active regions.
In a further exemplary embodiment, a transistor device is disclosed that includes a first active region positioned in a semiconductor substrate and having a first fin, and a first gate structure positioned above the first active region and extending across the first fin, the first gate structure having a first end surface and a first side surface. The disclosed transistor device also includes, among other things, a second active region positioned in the semiconductor substrate and spaced apart from the first active region, the second active region having a second fin, and a second gate structure positioned above the second active region and extending across the second fin, the second gate structure having a second end surface and a second side surface that is positioned laterally adjacent to and spaced apart from the first side surface of the first gate structure, wherein the second gate structure is oriented parallel to the first gate structure. Additionally, a third active region is positioned in the semiconductor substrate and spaced apart from the first active region, the third active region having a third fin, and a third gate structure is positioned above the third active region and extends across the third fin, the third gate structure having a third side surface and a third end surface that is positioned laterally adjacent to and spaced apart from the first end surface of the first gate structure, wherein the third gate structure is oriented parallel to the first and second gate structures. The illustrative transistor device further includes a fourth active region positioned in the semiconductor substrate and spaced apart from the second and third active regions, the fourth active region comprising a fourth fin, and a fourth gate structure positioned above the fourth active region and extending across the fourth fin, the fourth gate structure having a fourth end surface that is positioned laterally adjacent to and spaced apart from the second end surface of the second gate structure and a fourth side surface that is positioned laterally adjacent to and spaced apart from the third side surface of the third gate structure, wherein the fourth gate structure is oriented parallel to the first, second and third gate structures. Moreover, the device also includes a gate separation structure having a substantially planar upper surface that is positioned at a greater height level above the semiconductor substrate than an upper surface of each of the first, second, third and fourth fins. The gate separation structure includes, among other things, a first portion positioned between the laterally adjacent first and second side surfaces of the respective first and second gate structures, a second portion positioned between the laterally adjacent first and third end surfaces of the respective first and third gate structures, a third portion positioned between the laterally adjacent third and fourth side surfaces of the respective third and fourth gate structures, and a fourth portion positioned between the laterally adjacent second and fourth side surfaces of the respective second and fourth gate structures.

BRIEF DESCRIPTION OF THE DRAWINGS

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:

FIG. 1A is a perspective view of an illustrative prior art FinFET semiconductor device;

FIGS. 1B-1E are plan views simplistically depicting one illustrative prior art fabrication sequence for forming metal silicide regions on a prior art FinFET device; and

FIGS. 2A-20 depict various illustrative methods disclosed herein for forming gate structures for FinFET devices, and the resulting devices.

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.

DETAILED DESCRIPTION

Various illustrative embodiments of the present subject matter 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 systems, structures 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 generally relates to various methods of forming gate structures for FinFET devices and the resulting semiconductor devices. Moreover, as will be readily apparent to those skilled in the art upon a complete reading of the present application, the present method is applicable to a variety of devices, including, but not limited to, logic devices, memory devices, etc., and the methods disclosed herein may be employed to form N-type or P-type semiconductor devices. The methods and devices disclosed herein may be employed in manufacturing products using a variety of technologies, e.g., NMOS, PMOS, CMOS, etc., and they may be employed in manufacturing a variety of different devices, e.g., memory devices, logic devices, ASICs, etc. With reference to the attached figures, various illustrative embodiments of the methods and devices disclosed herein will now be described in more detail.
FIGS. 2A-20 depict various illustrative methods disclosed herein for forming gate structures for FinFET devices and the resulting devices. In general, the drawings contain a plan view and various cross-sectional views that are taken where indicated in the plan view. More specifically, the view “X-X” is taken along a line that passes through the fins 106, while the view “Y-Y” is a cross-section view that is taken transverse to the long axis of the fins 106. The illustrative FinFET devices that are depicted in the attached drawings may be either NMOS or PMOS devices. Additionally, various doped regions, e.g., source/drain regions, halo implant regions, well regions and the like, are also not depicted in the attached drawings. The illustrative integrated circuit product 100 depicted in the drawings is formed above an illustrative substrate 102 that may have a variety of configurations, such as the depicted bulk silicon configuration. The substrate 102 may also have a silicon-on-insulator (SOI) configuration that includes a bulk silicon layer, a buried insulation layer and an active layer, wherein semiconductor devices are formed in and above the active layer. The substrate 102 may be made of silicon or it may be made of materials other than silicon. Thus, the terms “substrate” or “semiconductor substrate” should be understood to cover all semiconducting materials and all forms of such materials. Lastly, in the examples disclosed herein, the FinFET devices will be formed using a replacement gate technique, but the methods disclosed herein could also be employed when using so-called gate-first manufacturing techniques to form the gate structures of the FinFET device.
FIG. 2A depicts the product 100 at a point in fabrication wherein several process operations have been performed. First, a plurality of active regions 102A-D were defined in the substrate 102 by the formation of isolation structures 104. The isolation structures 104 may be formed using well-known techniques. The overall size of the active regions 102A-D may vary depending upon the particular application. Next, a plurality of trenches 105 were formed in the substrate 102 to thereby define a plurality of fins 106. The illustrative FinFET devices disclosed herein will be depicted as being comprised of five illustrative fins 106. However, as will be recognized by those skilled in the art after a complete reading of the present application, the methods and devices disclosed herein may be employed when manufacturing FinFET devices having any number of fins. In one embodiment, the trenches 105 were formed by performing an etching process through a patterned etch mask (not shown) e.g., a patterned hard mask layer, using known etching techniques. The patterned etch mask may be patterned using known sidewall image transfer techniques and/or photolithographic techniques, combined with performing known etching techniques. In some applications, a further etching process may be performed to reduce the width or to “thin” the fins 106, although such a thinning process is not depicted in the attached drawings. For purposes of this disclosure and the claims, the use of the terms “fin” or “fins” should be understood to refer to fins that have not been thinned as well as fins that have been subjected to such a thinning etch process. Thereafter, a layer of insulating material 108 was deposited on the substrate 102 so as to over-fill the trenches 105. Then, a recess etching process was performed on the layer of insulating material 108 such that the insulating material 108 only remains in the bottom of the trenches 105 so as to locally isolate the fins 106 from one another. This recess etching process exposes the fins 106 to their approximate desired final fin height.
With continuing reference to FIG. 2A, the overall size, shape and configuration of the trenches 105 and fins 106 may vary depending on the particular application. The depth and width of the trenches 105 may vary depending upon the particular application. In one illustrative embodiment, based on current day technology, the depth of the trenches 105 may range from approximately 40-100 nm and the width of the trenches 105 may be about 20-60 nm. In some embodiments, the fins 106 may have a final width (at or near the bottom of the fin) within the range of about 5-20 nm. In the illustrative examples depicted in the attached figures, the trenches 105 and fins 106 are all of a uniform size and shape. However, such uniformity in the size and shape of the trenches 105 and the fins 106 is not required to practice at least some aspects of the inventions disclosed herein. In the example depicted herein, the trenches 105 are formed by performing an anisotropic etching process that results in the trenches 105 having a schematically depicted, generally rectangular configuration. In an actual real-world device, the sidewalls of the trenches 105 may be somewhat inwardly tapered, although that configuration is not depicted in the drawings. In some cases, the trenches 105 may have a reentrant profile near the bottom of the trenches 105. To the extent the trenches 105 are formed by performing a wet etching process, the trenches 105 may tend to have a more rounded configuration or non-linear configuration as compared to the generally rectangular configuration of the trenches 105 that are formed by performing an anisotropic etching process. Thus, the size and configuration of the trenches 105 and the fins 106, and the manner in which they are made, should not be considered a limitation of the present invention. For ease of disclosure, only the substantially rectangular trenches 105 and fins 106 will be depicted in subsequent drawings.
FIG. 2B depicts the product after one or more gate structure materials have been formed above the fins 106. As noted previously, the final gate structures for the FinFET devices disclosed herein may be formed using either gate-first or gate-last techniques. For purposes of disclosing the present subject matter, the FinFET devices will be depicted as being formed using a gate-last or replacement gate technique. Accordingly, FIG. 2B depicts the product at a point of fabrication wherein the materials that will become a sacrificial gate structure 107 for the FinFET devices are formed above the substrate 102 and the fins 106. The underlying active regions and fins 106 are depicted in dashed lines in the plan view of FIG. 2B. In one illustrative embodiment, the sacrificial gate structure 107 is comprised of an illustrative sacrificial gate insulation layer 109 and an illustrative sacrificial gate electrode 110. The sacrificial gate insulation layer 109 may be comprised of a variety of different materials, such as, for example, silicon dioxide, etc. Similarly, the sacrificial gate electrode 110 may also be of a material such as polysilicon or amorphous silicon, etc. As will be recognized by those skilled in the art after a complete reading of the present application, the sacrificial gate structure 107 depicted in the drawings is intended to be representative in nature. That is, the sacrificial gate structure 107 may be comprised of a variety of different materials and it may have a variety of configurations. In one illustrative embodiment, an oxidation process may be performed to form a sacrificial gate insulation layer 109 comprised of a material such as, for example, silicon dioxide, etc., on the fins 106. Thereafter, material of the sacrificial gate electrode 110 and a gate capping layer of material (not shown) may be deposited above the layer of sacrificial gate electrode material. The layers of material depicted in FIG. 2B, as well as the layers of material described below, may be formed by any of a variety of different known techniques, e.g., a chemical vapor deposition (CVD) process, an atomic layer deposition (ALD) process, a thermal growth process, spin-coating techniques, etc.
FIG. 2C depicts the product 100 after at least portions of the layers that comprise the sacrificial gate structure 107 have been patterned to define an opening 112. The patterning of such layer(s) of material may be accomplished by performing one or more etching processes, e.g., dry or wet, through a patterned mask layer (not shown), e.g., a photoresist mask, that is formed above the sacrificial gate electrode 110. In some cases, such a patterned mask may be formed above a layer of gate cap material (not shown) that is formed above the material layer that corresponds to the sacrificial gate electrode 110. In the depicted example, the patterning process results in removing the sacrificial gate insulation layer 109 exposed by the opening 112. Using the methods disclosed herein, the ends 110X of the line-type sacrificial gate structures 107 are patterned first, via formation of the trench or opening 112, prior to patterning the side surfaces of what will become the relatively long, line-type gate electrode structures 107 from the gate stack material layer(s). That is, in contrast to the prior art method discussed in the background section of this application, a transverse “cut” 115 of the gate stack material layer(s) is first performed to define the ends 110X of what will become the sacrificial gate structures 107 of the FinFET devices. Stated another way, the patterning of the materials of the sacrificial gate structure 107 is performed in a sequence that establishes the overall axial length of the gate structure 107 (by patterning the ends 110X first) and thereafter performing a patterning process (discussed more fully below) to define the lateral width of the gate structures 107 (by performing a patterning operation that defines the side surfaces of the sacrificial gate structures 107.
FIG. 2D depicts the product 100 after a gate separation structure 114 was formed in the opening 112. The gate separation structure 114 may be comprised of a variety of materials, e.g., silicon dioxide, silicon nitride, etc. In one embodiment, the gate separation structure 114 may be formed by blanket-depositing a layer of insulating material, e.g., silicon dioxide, on the product 100 so as to over-fill the opening 112. Then, one or more planarization processes, e.g., CMP processes, may be performed to remove the excess portions of the gate separation material positioned above the surface 107S of the sacrificial gate structure 107 and outside of the opening 112. In some cases, if desired, the gate separation structure 114 may be recessed by performing an etch-back etching process and a cap layer may be formed above the recessed gate separation structure 114 using traditional manufacturing techniques, i.e., deposition of the cap material followed by performing a CMP process. In the depicted example, the ends 110X of what will become the sacrificial gate structures 107 abut the horizontal portions 114H of the gate separation structure 114. The horizontal portion 114H prevents several problems that may occur when an epi growth process is performed on the fins 106, e.g., it prevents a short circuit from forming around the ends of what will become the gate structure, it prevents short circuits that might form in the direction indicated by the line 115A between adjacent devices during the epi growth process, etc. The vertical portion 114V may be formed for a variety of reasons, e.g., to remove what would otherwise be “dummy” gate structures (not shown), to prevent short circuits that might form in the direction indicated by the line 115B between adjacent devices during epi growth processed performed on the fins 106, etc. Note that the upper surface 114S of the gate separation structure 114 may be positioned about 40-120 nm above the upper surface 106S of the fins 106.
FIG. 2E depicts the product 100 at an advanced state of fabrication. In addition to the cross-sectional views “X-X” and “Y-Y”, further illustrative cross-sectional views “A-A” and “B-B” are also shown in FIGS. 2E-2F. The “A-A” view is a cross-sectional view taken between the fins 106 across the active regions 102A and 102C. The “B-B” view is a cross-sectional view taken between the sacrificial gate structures 107 across the active regions 102C and 102D.
FIG. 2E depicts the product 100 after several process operations have been performed to pattern various layers of material so as to define the sacrificial gate structures 107. More specifically, a “gate patterning” process operation that involves performing one or more etching processes has been performed on the materials of the gate electrode structure 107 through a patterned mask layer 116 to arrive at the structure depicted in FIG. 2E. This etching process defines the side surfaces 110Y of the sacrificial gate electrodes 107. So as not to obscure the present invention, the patterned masking layer 116 has not been shown in the plan view of FIG. 2E. The patterning of such layer(s) of material may be accomplished by performing one or more etching processes, e.g., dry or wet, through the patterned mask layer 116, e.g., a photoresist mask, a hard mask, etc., that is formed above the sacrificial gate electrode material 110. This “gate patterning” process operation results in the formation of gate structures 107A (that span across the active regions 102A-102B) and the gate structures 107B, 107C (that span across the active regions 102C, 102D, respectively. As will be recognized by those skilled in the art, in this patterning step, the materials that will be used to define the sacrificial gate structures 107 for the product 100 are patterned to their desired lateral width that corresponds approximately to the channel length of the finished FinFET transistor devices.
FIG. 2F depicts the device 100 after several process operations were performed. First, sidewall spacers 122 were formed adjacent the structures depicted in FIG. 2E. The sidewall spacers 122 may be formed by depositing a layer of spacer material above the structures depicted in FIG. 2E, and thereafter performing an anisotropic etching process on the layer of spacer material so as to result in the spacers 122 depicted in the FIG. 2F. Thereafter, an epi semiconductor material 124, e.g., silicon, silicon/germanium, was formed on the exposed portions of the fins 106 positioned outside of the spacers 122. Note that, due to the presence of the gate separation structure 114 that contacts the end surfaces 110X of the gate structures 107B and 107C, epi semiconductor material 124 is prevented from forming around the ends 110X of the gate structures 107B/107C, thereby reducing or eliminating the chance for undesirable bridging between the source/drain regions of the FinFET devices shown in the drawings. In the depicted example, portions of the epi material 124 may contact the sidewall spacers 122 that are formed on both the gate structure, e.g., 107A, and the gate separation structure 114. Due to the presence of the vertical portion 114V of the gate separation structure 114, the epi semiconductor material 124 is prevented from bridging the distance between the source/drain regions of the devices 102A, 102C (see view A-A).
The next series of process operations involves formation of a replacement gate structure of the devices. FIG. 2G depicts the product 100 after a layer of insulating material 130, e.g., silicon dioxide, has been blanket-deposited above the epi semiconductor material 124 and after a planarization process was performed to planarize the upper surface of the layer of insulating material with the upper surface of the patterned mask layer 116 (or gate cap layer if present).
FIG. 2H depicts the device 100 after several process operations were performed. First, an etching process was performed to remove the patterned mask layer 116 (gate cap layer if present) so as to thereby expose the sacrificial gate electrode 110. Then, one or more etching processes were performed to remove the exposed sacrificial gate electrode 110 and the sacrificial gate insulation layer 109 so as to define a gate cavity 132 where the final gate structure (the “replacement gate” of the device) will be formed. Typically, the sacrificial gate insulation layer 109 is removed as part of the replacement gate technique so as to expose the upper surface 106S of the fins 106 within the gate cavities 132, as depicted herein. However, the sacrificial gate insulation layer 109 may not be removed in all applications. Even in cases where the sacrificial gate insulation layer 109 is intentionally removed, there will typically be a very thin native oxide layer (not shown) that forms on the fins 106 within the gate cavity 132.
FIG. 2I depicts the product 100 after a schematically depicted replacement gate structure “R” and a gate cap layer 134 have been formed in the gate cavities 132. The replacement gate structure is intended to be representative in nature of any type of gate structure that may be employed in manufacturing integrated circuit products using so-called gate-last (replacement gate) manufacturing techniques. Such a replacement gate structure typically comprises a high-k (k value greater than 10) gate insulation layer (not individually shown), such as hafnium oxide, one or more metal layers (not individually shown) (e.g., layers of titanium nitride or TiAlC, depending upon the type of transistor device being manufactured), and a bulk conductive material layer (not individually shown), such as tungsten or aluminum. After the materials of the replacement gate structure are formed in the gate cavity 132, a CMP process is typically performed to remove the excess materials positioned outside of the gate cavity 132. Thereafter, one or more dry or wet etching processes may be performed to remove portions of the materials of the replacement gate structure and thereby define a recess within the upper portion of the gate cavity 132. The gate cap layer 134 may then be formed in each of the recesses. The gate cap layer 134 may be comprised of a variety of materials, e.g., silicon nitride, etc. In one embodiment, the cap layers 134 may be formed by blanket-depositing a cap layer material, e.g., silicon nitride, on the product 100 so as to over-fill the recess in the gate cavities 132 above the replacement gate structures and thereafter performing a planarization process, e.g., CMP processes, to remove the portions of the cap layer material positioned above the surface of the layer of insulating material 130 and outside of the gate cavities 132.
As will be appreciated and understood by those skilled in the art after a complete reading of the present application, there are several novel methods and devices disclosed herein. FIG. 2J-2M depict one illustrative example where the methods disclosed herein may be employed to manufacture integrated circuit products. FIG. 2J depicts a product 100 comprised of six illustrative spaced-apart active regions 102A-F. The active regions are defined by the above-described isolation structure 104. FIG. 2J depicts the desired configuration of the gate structures 140 (which may be final gate structures or sacrificial gate structures) for the finished integrated circuit product. FIG. 2J depicts the device at a point in fabrication wherein the fins 106 and the local isolation material 108 have been formed. Note that, in this example, the active regions 102A, 102B share a common gate structure 140, while all of the other gate structures span only a single active region.
FIG. 2K depicts the beginning of one illustrative sequence disclosed herein for forming the gate structures 140 shown in FIG. 2J. The active regions and the fins 106 are depicted in dashed lines in FIGS. 2K-2N. Initially, the stack of materials 140S that will comprise the gate structure 140 (be it a final gate structure or a sacrificial gate structure) are blanket-deposited across all of the active regions. FIG. 2L depicts the product after several process operations were performed. First, one or more etching processes were performed to form a plurality of the above-described openings or trenches 112 through the stack of materials 140S. The formation of the trenches 112 defines what will become the end surfaces 110X of the gate structures 140. In this particular example, trenches 112 are spaced-apart trenches, i.e., two of the spaced-apart trenches 112 are required to define the overall axial length of the final gate structures 140. Note that, due to the fact that the active regions 102A, 102B will share a common gate electrode 140, a trench 112 is not present between the active regions 102A, 102B. FIG. 2L also depicts the product 100 after the above-described gate separation structure 114 was formed in the spaced apart trenches 112. FIG. 2M depicts the product after another etching process was performed on the stack of materials 140S through a patterned mask layer (not shown) to define the side surfaces 110Y of the gate structures 140.
FIGS. 2N-2P depict the beginning of another illustrative sequence disclosed herein for forming the gate structures 140 shown in FIG. 2J. Initially, the stack of materials 140S that will comprise the gate structure 140 (be it a final gate structure or a sacrificial gate structure) are blanket-deposited across all of the active regions, as depicted in FIG. 2K. Then, as shown in FIG. 2N, a continuous trench 112 was formed in the stack of materials 140S by performing an etching process through a patterned etch mask (not shown). The formation of the continuous trench 112 defines what will become the end surfaces 110X of the gate structures 140. In this particular example, since the trench 112 is continuous in nature, only a single trench 112 needs to be formed to define the overall axial length of the gate structures 140. Note that, due to the fact that the active regions 102A, 102B will share a common gate electrode 140, a portion of the trench 112 is not present between the active regions 102A, 102B. FIG. 2N also depicts the product 100 after the above-described gate separation structure 114 was formed in the continuous trench/opening 112. FIG. 2O depicts the product after another etching process was performed on the stack of materials 140S through a patterned mask layer (not shown) to define the side surfaces 110Y of the gate structures 140. As noted above, due to the presence of the gate separation structure 114, undesirable epi bridging is prevented between the ends 110X of the electrodes 140, as well as between the epi material on adjacent devices (e.g., 102A and 102C).
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. Note that the use of terms, such as “first,” “second,” “third” or “fourth” to describe various processes or structures in this specification and in the attached claims is only used as a shorthand reference to such steps/structures and does not necessarily imply that such steps/structures are performed/formed in that ordered sequence. Of course, depending upon the exact claim language, an ordered sequence of such processes may or may not be required. Accordingly, the protection sought herein is as set forth in the claims below.

Claims

What is claimed:

1. A transistor device, comprising:

first and second spaced-apart active regions positioned in a semiconductor substrate, each of said respective first and second spaced-apart active regions comprising at least one fin;

first and second spaced-apart gate structures positioned above said respective first and second active regions, respectively, each of said first and second gate structures comprising end surfaces; and

a gate separation structure positioned between said first and second spaced-apart gate structures, wherein first and second opposing surfaces of said gate separation structure abut an entirety of said respective end surfaces of said first and second spaced-apart gate structures, and wherein an upper surface of said gate separation structure is positioned at a greater height level above said semiconductor substrate than an upper surface of said at least one fin comprising each of said respective first and second spaced-apart active regions.

2. The transistor device of claim 1, wherein said upper surface of said gate separation structure is positioned at a height level above said semiconductor substrate that is approximately even with a height level of an upper surface of an uppermost conductive material of said first and second gate structures.

3. The transistor device of claim 1, further comprising;

a first sidewall spacer positioned adjacent opposing side surfaces of said gate separation structure; and

an epitaxial semiconductor material positioned on said at least one fin comprising each of said respective first and second spaced-apart active regions, said epitaxial semiconductor material abutting said first sidewall spacer.

4. The transistor device of claim 3, further comprising a second sidewall spacer positioned adjacent sidewall surfaces of each of said first and second spaced-apart gate structures, said epitaxial semiconductor material further abutting said second sidewall spacers.

5. The transistor device of claim 1, further comprising:

a third active region positioned in said semiconductor substrate and spaced apart from said first active region, said third active region comprising at least one fin; and

a third gate structure positioned above said third active region, said third gate structure being oriented substantially parallel to said first gate structure, wherein said first and third gate structures have side surfaces, and wherein a portion of said gate separation structure is positioned in an area between said side surfaces of said first and third gate structures.

6. The transistor device of claim 1, wherein each of said first and second spaced-apart gate structures comprise a high-k gate insulation layer and one or more metal layers positioned above said high-k gate insulation layer.

7. A transistor device, comprising:

first and second spaced-apart gate structures positioned above and extending across said at least one fin of each of said respective first and second spaced-apart active regions, each of said first and second spaced-apart gate structures comprising side surfaces, wherein said first gate structure is oriented parallel to said second gate structure; and

a gate separation structure positioned between adjacent side surfaces of said first and second spaced-apart gate structures, wherein an upper surface of said gate separation structure is positioned at a greater height level above said semiconductor substrate than an upper surface of said at least one fin comprising each of said respective first and second spaced-apart active regions.

8. The transistor device of claim 7, wherein said upper surface of said gate separation structure is positioned at a height level above said semiconductor substrate that is approximately even with a height level of an upper surface of an uppermost conductive material of said first and second gate structures.

9. The transistor device of claim 7, further comprising:

10. The transistor device of claim 9, further comprising a second sidewall spacer positioned adjacent sidewall surfaces of each of said first and second spaced-apart gate structures, said epitaxial semiconductor material further abutting said second sidewall spacers.

11. The transistor device of claim 7, further comprising:

a third gate structure positioned above said third active region and extending across said at least one fin of said third active region, said third gate structure being oriented substantially parallel to each of said first and second spaced-apart gate structures, wherein said first and third gate structures have end surfaces and wherein a portion of said gate separation structure extends between and abuts an entirety of said end surfaces of said first and third gate structures.

12. The transistor device of claim 11, further comprising a fourth active region positioned in said semiconductor substrate and spaced apart from each of said second and third active regions, said fourth active region comprising at least one fin, wherein said third gate structure has a side surface that is positioned laterally adjacent to and spaced apart from a side surface of a gate structure extending across said at least one fin of said fourth active region, and wherein a further portion of said gate separation structure is positioned between said laterally adjacent side surfaces of said fourth gate structure and said gate structure extending across said at least one fin of said fourth active region.

13. The transistor device of claim 12, wherein said gate structure extending across said at least one fin of said fourth active region comprises a portion of said second gate structure that extends continuously from said second active region and across said fourth active region.

14. The transistor device of claim 12, wherein said gate separation structure has a substantially T-shaped configuration when viewed from above.

15. The transistor device of claim 7, wherein each of said first and second spaced-apart gate structures comprise a high-k gate insulation layer and one or more metal layers positioned above said high-k gate insulation layer.

16. A transistor device, comprising:

a first active region positioned in a semiconductor substrate and comprising a first fin;

a first gate structure positioned above said first active region and extending across said first fin, said first gate structure having a first end surface and a first side surface;

a second active region positioned in said semiconductor substrate and spaced apart from said first active region, said second active region comprising a second fin;

a second gate structure positioned above said second active region and extending across said second fin, said second gate structure having a second end surface and a second side surface that is positioned laterally adjacent to and spaced apart from said first side surface of said first gate structure, wherein said second gate structure is oriented parallel to said first gate structure;

a third active region positioned in said semiconductor substrate and spaced apart from said first active region, said third active region comprising a third fin;

a third gate structure positioned above said third active region and extending across said third fin, said third gate structure having a third side surface and a third end surface that is positioned laterally adjacent to and spaced apart from said first end surface of said first gate structure, wherein said third gate structure is oriented parallel to said first and second gate structures;

a fourth active region positioned in said semiconductor substrate and spaced apart from said second and third active regions, said fourth active region comprising a fourth fin;

a fourth gate structure positioned above said fourth active region and extending across said fourth fin, said fourth gate structure having a fourth end surface that is positioned laterally adjacent to and spaced apart from said second end surface of said second gate structure and a fourth side surface that is positioned laterally adjacent to and spaced apart from said third side surface of said third gate structure, wherein said fourth gate structure is oriented parallel to said first, second, and third gate structures;

a gate separation structure having a substantially planar upper surface that is positioned at a greater height level above said semiconductor substrate than an upper surface of each of said first, second, third and fourth fins, said gate separation structure comprising:

a first portion positioned between said laterally adjacent first and second side surfaces of said respective first and second gate structures;

a second portion positioned between said laterally adjacent first and third end surfaces of said respective first and third gate structures;

a third portion positioned between said laterally adjacent third and fourth side surfaces of said respective third and fourth gate structures; and

a fourth portion positioned between said laterally adjacent second and fourth side surfaces of said respective second and fourth gate structures.

17. The transistor device of claim 16, wherein said gate separation structure has a substantially cross-shaped configuration when viewed from above.

18. The transistor device of claim 16, wherein said second portion of said gate separation structure abuts an entirety of said first and third end surfaces of said respective first and third gate structures, and wherein said fourth portion of said gate separation structure abuts an entirety of said second and fourth end surfaces of said respective second and fourth gate structures.

19. The transistor device of claim 16, further comprising:

a first sidewall spacer positioned adjacent sidewall surfaces of said gate separation structure;

a second sidewall spacer positioned adjacent sidewall surfaces of each of said first, second, third and fourth gate structures; and

an epitaxial semiconductor material positioned on said first, second, third and fourth fins, said epitaxial semiconductor material abutting said first and second sidewall spacers.

20. The transistor device of claim 16, wherein each of said first, second, third and fourth gate structures comprise a high-k gate insulation layer and one or more metal layers positioned above said high-k gate insulation layer.