Patent Application
20220415792
Embodiments of the present disclosure generally relate to the field of integrated circuit (IC) manufacturing, and in particular to gate structure contacts.
Continued growth in computing devices, virtual machines and cloud computing will continue to increase the demand for increased density of transistors in an IC.
Embodiments described herein may be related to apparatuses, processes, and techniques used to construct via gate contact (VCG) between a metal gate of a gate structure and a metallization layer, which may be referred to as M0. In embodiments, the VCG is split into two separate portions. The bottom portion, VCG, may be oversized with respect to the metal gate and may be self-aligned to a trench connector that is in a same layer as the bottom portion of the VCG. The top portion, which may be referred to as VCx, may be an inverse taper that may be used to electrically couple the bottom portion VCG, or electrically couple another trench contact, with the metallization layer.
Legacy implementations, as discussed further below with respect to
In particular with legacy implementations, as the M0 pitch scales down, it becomes more difficult to align a VCG and a via trench contact (VCT) to the M0. This problem is particularly difficult with a subtractive M0, where there is no higher-k dielectric to prevent time-dependent dielectric breakdown. A concurrent issue in legacy implementations is that in standard cells, the M0-to-VCG-to-gate connections becomes very tight, often leaving zero to negative VCG-to-gate enclosure which results in high risk of a contact open.
A result of embodiments described herein that provide the bottom VCG with a large area, and the top VCx with a small top area allows standard cells to be scaled further by (1) fully contacting the gate, and (2) by increasing the margin in the contact with M0 to allow for edge placement error (EPE) during manufacturing. In particular, when M0 itself has an inverse taper due to subtractive metal formation during manufacture. This will allow for improved quality and increased density of transistors on an IC. In addition, embodiments of processes described herein allow the VCG to self-align to the gate contact during manufacture.
In the following detailed description, reference is made to the accompanying drawings which form a part hereof, wherein like numerals designate like parts throughout, and in which is shown by way of illustration embodiments in which the subject matter of the present disclosure may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments is defined by the appended claims and their equivalents.
For the purposes of the present disclosure, the phrase “A and/or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).
The description may use perspective-based descriptions such as top/bottom, in/out, over/under, and the like. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of embodiments described herein to any particular orientation.
The description may use the phrases “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present disclosure, are synonymous.
The term “coupled with,” along with its derivatives, may be used herein. “Coupled” may mean one or more of the following. “Coupled” may mean that two or more elements are in direct physical or electrical contact. However, “coupled” may also mean that two or more elements indirectly contact each other, but yet still cooperate or interact with each other, and may mean that one or more other elements are coupled or connected between the elements that are said to be coupled with each other. The term “directly coupled” may mean that two or more elements are in direct contact.
Various operations may be described as multiple discrete operations in turn, in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be construed as to imply that these operations are necessarily order dependent.
As used herein, the term “module” may refer to, be part of, or include an ASIC, an electronic circuit, a processor (shared, dedicated, or group) and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
Various Figures herein may depict one or more layers of one or more package assemblies. The layers depicted herein are depicted as examples of relative positions of the layers of the different package assemblies. The layers are depicted for the purposes of explanation, and are not drawn to scale. Therefore, comparative sizes of layers should not be assumed from the Figures, and sizes, thicknesses, or dimensions may be assumed for some embodiments only where specifically indicated or discussed.
Various embodiments may include any suitable combination of the above-described embodiments including alternative (or) embodiments of embodiments that are described in conjunctive form (and) above (e.g., the “and” may be “and/or”). Furthermore, some embodiments may include one or more articles of manufacture (e.g., non-transitory computer-readable media) having instructions, stored thereon, that when executed result in actions of any of the above-described embodiments. Moreover, some embodiments may include apparatuses or systems having any suitable means for carrying out the various operations of the above-described embodiments.
Within layer 112 there may be a VCG 115 that is electrically and physically coupled to the gate 102. Layer 112 may also include trench connectors 114, 116 that may be electrically and physically coupled, respectively, with trench connector 106, 108. In embodiments, layer 112 may include a dielectric 118, which may serve as a spacer for VCG 115 self-alignment during manufacture. In embodiments, the trench connectors 114, 116 may have an inverse taper from the bottom of the trench connectors 114, 116 where they connect, respectively with trench connectors 106, 108, to a top of the trench connectors 114, 116. In other embodiments, the trench connectors 114, 116 may have no taper, or an outward taper.
In embodiments, the VCG 115 may have an outward taper from the VCG 115 bottom where it couples with the gate 102, to the top of the VCG 115. The VCx 120 may be coupled with the metal 0 layer (M0) 126. At either side of the VCx there may be an inverse taper trench connector 122, 124. In embodiments, a bottom of the trench connector 122, 124, where it couples, respectively, with the top of the trench connector 114, 116 tapers inward to the top of the trench connector 122, 124, where it couples with the M0 126.
In embodiments, the dielectric 118 within layer 112 may have various cavities formed into which the trench connectors 114, 116 and the VCG 115 may be formed. A geometry of the various cavities will produce respective geometries (e.g. tapers) in the trench connectors 114, 116 and the VCG 115. These various cavities within the dielectric 118 may be used to self-align the VCG 115 with the trench connectors 114, 116, as well as with the gate 102.
Because of the upward taper, this legacy implementation may result in the top of the VCT 234 being very close to the M0 230a, possibly causing a short, as shown in region 231, resulting in electrical contact between the VCT 234 and the M0 230a. This is particularly true given the edge placement error (EPE) during manufacture, particularly with respect to manufacturing integrated circuits with a higher density of transistors.
In legacy implementations, the VCG 238 may be a single via with a traditional via structure, having an outward taper from the bottom of the VCG 238 via to the top. In this implementation, because of the height of the via, the top of the VCG 238 may be very broad due to its high aspect ratio, and be very close to the M0 230c, possibly causing a short, as shown in region 237. Again, this is particularly true given EPE during manufacture, particularly with respect to manufacturing integrated circuits with a higher density of transistors.
As shown, a top portion of the VCG 315 is coupled with a bottom portion of the VCx 320, where a bottom of the VCG 315 that is coupled with the gate 302 may have a larger surface area than a bottom of the VCX 320 that is coupled with the top of the VCG 315. The sides of the VCG 315 tapers outward from the bottom to the top. In this way, the bottom of the VCG 315 provides a good electrical connection with the gate 302, and even permits a partial overlap with a gate cut 303, that may be used to electrically and physically decouple portions of the gate 302, 305.
In embodiments, the VCG 415 may be elongated parallel to the gate 402 to maximize contact area with the gate 402. In embodiments, the elongation of the VCG 415 may overlap in part with a gate cut 403, which may be similar to gate cut 303 of
At block 702, the process may include forming a first layer of on top of a trench connector and a gate structure, with a first trench connector at a first side of the gate structure and a second trench connector at a second side of the gate structure opposite the first side of the gate structure, the gate structure including a gate and a dielectric material, wherein the first layer includes a first conductive via having a bottom side and a top side opposite the bottom side, wherein the bottom side is electrically coupled with the gate structure, and wherein the first conductive via has outwardly tapered walls extending from the bottom side of the first conductive via to the top side of the first conductive via.
At block 704, the process may further include forming a second layer on top of the first layer, wherein the second layer includes a second conductive via having a bottom side and a top side opposite the bottom side, wherein the bottom side of the second conductive via is electrically coupled with the top side of the first conductive via, and wherein the second conductive via has a inwardly tapered walls extending from the bottom side of the second conductive via to the top side of the second conductive via.
Implementations of embodiments of the invention may be formed or carried out on a substrate, such as a semiconductor substrate. In one implementation, the semiconductor substrate may be a crystalline substrate formed using a bulk silicon or a silicon-on-insulator substructure. In other implementations, the semiconductor substrate may be formed using alternate materials, which may or may not be combined with silicon, that include but are not limited to germanium, indium antimonide, lead telluride, indium arsenide, indium phosphide, gallium arsenide, indium gallium arsenide, gallium antimonide, or other combinations of group III-V or group IV materials. Although a few examples of materials from which the substrate may be formed are described here, any material that may serve as a foundation upon which a semiconductor device may be built falls within the spirit and scope of the present invention.
A plurality of transistors, such as metal-oxide-semiconductor field-effect transistors (MOSFET or simply MOS transistors), may be fabricated on the substrate. In various implementations of the invention, the MOS transistors may be planar transistors, nonplanar transistors, or a combination of both. Nonplanar transistors include FinFET transistors such as double-gate transistors and tri-gate transistors, and wrap-around or all-around gate transistors such as nanoribbon and nanowire transistors. Although the implementations described herein may illustrate only planar transistors, it should be noted that the invention may also be carried out using nonplanar transistors.
Each MOS transistor includes a gate stack formed of at least two layers, a gate dielectric layer and a gate electrode layer. The gate dielectric layer may include one layer or a stack of layers. The one or more layers may include silicon oxide, silicon dioxide (SiO2) and/or a high-k dielectric material. The high-k dielectric material may include elements such as hafnium, silicon, oxygen, titanium, tantalum, lanthanum, aluminum, zirconium, barium, strontium, yttrium, lead, scandium, niobium, and zinc. Examples of high-k materials that may be used in the gate dielectric layer include, but are not limited to, hafnium oxide, hafnium silicon oxide, lanthanum oxide, lanthanum aluminum oxide, zirconium oxide, zirconium silicon oxide, tantalum oxide, titanium oxide, barium strontium titanium oxide, barium titanium oxide, strontium titanium oxide, yttrium oxide, aluminum oxide, lead scandium tantalum oxide, and lead zinc niobate. In some embodiments, an annealing process may be carried out on the gate dielectric layer to improve its quality when a high-k material is used.
The gate electrode layer is formed on the gate dielectric layer and may consist of at least one P-type workfunction metal or N-type workfunction metal, depending on whether the transistor is to be a PMOS or an NMOS transistor. In some implementations, the gate electrode layer may consist of a stack of two or more metal layers, where one or more metal layers are workfunction metal layers and at least one metal layer is a fill metal layer.
For a PMOS transistor, metals that may be used for the gate electrode include, but are not limited to, ruthenium, palladium, platinum, cobalt, nickel, and conductive metal oxides, e.g., ruthenium oxide. A P-type metal layer will enable the formation of a PMOS gate electrode with a workfunction that is between about 4.9 eV and about 5.2 eV. For an NMOS transistor, metals that may be used for the gate electrode include, but are not limited to, hafnium, zirconium, titanium, tantalum, aluminum, alloys of these metals, and carbides of these metals such as hafnium carbide, zirconium carbide, titanium carbide, tantalum carbide, and aluminum carbide. An N-type metal layer will enable the formation of an NMOS gate electrode with a workfunction that is between about 3.9 eV and about 4.2 eV.
In some implementations, the gate electrode may consist of a “U”-shaped structure that includes a bottom portion substantially parallel to the surface of the substrate and two sidewall portions that are substantially perpendicular to the top surface of the substrate. In another implementation, at least one of the metal layers that form the gate electrode may simply be a planar layer that is substantially parallel to the top surface of the substrate and does not include sidewall portions substantially perpendicular to the top surface of the substrate. In further implementations of the invention, the gate electrode may consist of a combination of U-shaped structures and planar, non-U-shaped structures. For example, the gate electrode may consist of one or more U-shaped metal layers formed atop one or more planar, non-U-shaped layers.
In some implementations of the invention, a pair of sidewall spacers may be formed on opposing sides of the gate stack that bracket the gate stack. The sidewall spacers may be formed from a material such as silicon nitride, silicon oxide, silicon carbide, silicon nitride doped with carbon, and silicon oxynitride. Processes for forming sidewall spacers are well known in the art and generally include deposition and etching process steps. In an alternate implementation, a plurality of spacer pairs may be used, for instance, two pairs, three pairs, or four pairs of sidewall spacers may be formed on opposing sides of the gate stack.
As is well known in the art, source and drain regions are formed within the substrate adjacent to the gate stack of each MOS transistor. The source and drain regions are generally formed using either an implantation/diffusion process or an etching/deposition process. In the former process, dopants such as boron, aluminum, antimony, phosphorous, or arsenic may be ion-implanted into the substrate to form the source and drain regions. An annealing process that activates the dopants and causes them to diffuse further into the substrate typically follows the ion implantation process. In the latter process, the substrate may first be etched to form recesses at the locations of the source and drain regions. An epitaxial deposition process may then be carried out to fill the recesses with material that is used to fabricate the source and drain regions. In some implementations, the source and drain regions may be fabricated using a silicon alloy such as silicon germanium or silicon carbide. In some implementations the epitaxially deposited silicon alloy may be doped in situ with dopants such as boron, arsenic, or phosphorous. In further embodiments, the source and drain regions may be formed using one or more alternate semiconductor materials such as germanium or a group III-V material or alloy. And in further embodiments, one or more layers of metal and/or metal alloys may be used to form the source and drain regions.
One or more interlayer dielectrics (ILD) are deposited over the MOS transistors. The ILD layers may be formed using dielectric materials known for their applicability in integrated circuit structures, such as low-k dielectric materials. Examples of dielectric materials that may be used include, but are not limited to, silicon dioxide (SiO2), carbon doped oxide (CDO), silicon nitride, organic polymers such as perfluorocyclobutane or polytetrafluoroethylene, fluorosilicate glass (FSG), and organosilicates such as silsesquioxane, siloxane, or organosilicate glass. The ILD layers may include pores or air gaps to further reduce their dielectric constant.
Depending on its applications, computing device 800 may include other components that may or may not be physically and electrically coupled to the board 802. These other components include, but are not limited to, volatile memory (e.g., DRAM), non-volatile memory (e.g., ROM), flash memory, a graphics processor, a digital signal processor, a crypto processor, a chipset, an antenna, a display, a touchscreen display, a touchscreen controller, a battery, an audio codec, a video codec, a power amplifier, a global positioning system (GPS) device, a compass, an accelerometer, a gyroscope, a speaker, a camera, and a mass storage device (such as hard disk drive, compact disk (CD), digital versatile disk (DVD), and so forth).
The communication chip 806 enables wireless communications for the transfer of data to and from the computing device 800. The term “wireless” and its derivatives may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a non-solid medium. The term does not imply that the associated devices do not contain any wires, although in some embodiments they might not. The communication chip 806 may implement any of a number of wireless standards or protocols, including but not limited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE 802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, derivatives thereof, as well as any other wireless protocols that are designated as 3G, 4G, 5G, and beyond. The computing device 800 may include a plurality of communication chips 806. For instance, a first communication chip 806 may be dedicated to shorter range wireless communications such as Wi-Fi and Bluetooth and a second communication chip 806 may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others.
The processor 804 of the computing device 800 includes an integrated circuit die packaged within the processor 804. In some implementations of the invention, the integrated circuit die of the processor includes one or more devices, such as MOS-FET transistors built in accordance with implementations of the invention. The term “processor” may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory.
The communication chip 806 also includes an integrated circuit die packaged within the communication chip 806. In accordance with another implementation of the invention, the integrated circuit die of the communication chip includes one or more devices, such as MOS-FET transistors built in accordance with implementations of the invention.
In further implementations, another component housed within the computing device 800 may contain an integrated circuit die that includes one or more devices, such as MOS-FET transistors built in accordance with implementations of the invention.
In various implementations, the computing device 800 may be a laptop, a netbook, a notebook, an ultrabook, a smartphone, a tablet, a personal digital assistant (PDA), an ultra mobile PC, a mobile phone, a desktop computer, a server, a printer, a scanner, a monitor, a set-top box, an entertainment control unit, a digital camera, a portable music player, or a digital video recorder. In further implementations, the computing device 800 may be any other electronic device that processes data.
The interposer 900 may be formed of an epoxy resin, a fiberglass-reinforced epoxy resin, a ceramic material, or a polymer material such as polyimide. In further implementations, the interposer 900 may be formed of alternate rigid or flexible materials that may include the same materials described above for use in a semiconductor substrate, such as silicon, germanium, and other group III-V and group IV materials.
The interposer 900 may include metal interconnects 908 and vias 910, including but not limited to through-silicon vias (TSVs) 912. The interposer 900 may further include embedded devices 914, including both passive and active devices. Such devices include, but are not limited to, capacitors, decoupling capacitors, resistors, inductors, fuses, diodes, transformers, sensors, and electrostatic discharge (ESD) devices. More complex devices such as radio-frequency (RF) devices, power amplifiers, power management devices, antennas, arrays, sensors, and MEMS devices may also be formed on the interposer 900. In accordance with embodiments of the invention, apparatuses or processes disclosed herein may be used in the fabrication of interposer 900.
The above description of illustrated embodiments, including what is described in the Abstract, is not intended to be exhaustive or to limit embodiments to the precise forms disclosed. While specific embodiments are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the embodiments, as those skilled in the relevant art will recognize.
These modifications may be made to the embodiments in light of the above detailed description. The terms used in the following claims should not be construed to limit the embodiments to the specific implementations disclosed in the specification and the claims. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.
The following paragraphs describe examples of various embodiments.
Example 1 is an integrated circuit structure, comprising: a gate structure above a channel structure, the gate structure comprising a gate and a gate dielectric; a first conductive via having a bottom side and a top side opposite the bottom side, the bottom side of the first conductive via electrically coupled with the gate, the first conductive via having outwardly tapered walls extending from the bottom side of the first conductive via to the top side of the first conductive via; a second conductive via having a bottom side and a top side opposite the bottom side, the bottom side of the second conductive via electrically coupled with the top side of the first conductive via, the second conductive via having inwardly tapered walls from the bottom side of the second conductive via to the top side of the second conductive via.
Example 2 includes the integrated circuit structure of example 1, wherein the walls of the first conductive via have a slope between 90° and 85°, and wherein the walls of the second conductive via have a slope between 90° and 95°.
Example 3 includes the integrated circuit structure of example 1, further comprising a metallization layer electrically coupled with the top side of the second conductive via.
Example 4 includes the integrated circuit structure of example 1, further comprising a barrier liner between the bottom side of the second conductive via and the top side of the first conductive via.
Example 5 includes the integrated circuit structure of example 1, wherein the bottom side of the first conductive via overlaps with a cut in the gate.
Example 6 includes the integrated circuit structure of anyone of examples 1-5, wherein the first metal via and the second metal via include copper.
Example 7 is an integrated circuit structure, comprising: a trench connector above a source or drain structure, the trench connector comprising a conductive metal; a first conductive via having a bottom side and a top side opposite the bottom side, the bottom side of the first conductive via electrically coupled with the trench connector, the first conductive via having outwardly tapered walls extending from the bottom side of the first conductive via to the top side of the first conductive via; a second conductive via having a bottom side and a top side opposite the bottom side, the bottom side of the second conductive via electrically coupled with the top side of the first conductive via, the second conductive via having inwardly tapered walls from the bottom side of the second conductive via to the top side of the second conductive via; a third conductive via having a first side and a second side opposite the first side, the bottom side of the third conductive via electrically coupled with gate structure above a channel structure, the gate structure comprising a gate and a gate dielectric; wherein the third conductive via has outwardly tapered walls extending from the bottom side of the third conductive via to the top side of the third conductive via; and wherein the first conductive via and the third conductive via are within a layer of the integrated circuit structure.
Example 8 includes the integrated circuit structure of example 7, wherein the top side of the second conductive via is electrically coupled with a metallization layer.
Example 9 includes the integrated circuit structure of example 7, wherein the third conductive via is electrically coupled with the metallization layer.
Example 10 includes the integrated circuit structure of example 7, wherein the walls of the first conductive via have a slope between 90° and 85° and wherein the walls of the second conductive via have a slope between 90° and 95°.
Example 11 includes the integrated circuit structure of any one of example 7-10, wherein the first conductive via, the second conductive via, and the third conductive via include copper.
Example 12 is a method, comprising: forming a first layer of on top of a trench connector and a gate structure, with a first trench connector at a first side of the gate structure and a second trench connector at a second side of the gate structure opposite the first side of the gate structure, the gate structure including a gate and a dielectric material, wherein the first layer includes a first conductive via having a bottom side and a top side opposite the bottom side, wherein the bottom side is electrically coupled with the gate structure, wherein the first conductive via has outwardly tapered walls extending from the bottom side of the first conductive via to the top side of the first conductive via; and forming a second layer on top of the first layer, wherein the second layer includes a second conductive via having a bottom side and a top side opposite the bottom side, wherein the bottom side of the second conductive via is electrically coupled with the top side of the first conductive via, wherein the second conductive via has a inwardly tapered walls extending from the bottom side of the second conductive via to the top side of the second conductive via.
Example 13 includes the method of example 12, wherein forming the first layer on top of the trench connector and the gate structure further includes forming a first pillar on top of the first trench connector and forming a second pillar on top of the second trench connector, the first pillar and the second pillar having, respectively, a bottom side and a top side opposite the bottom side, wherein the walls of the first pillar and the second pillar are inwardly tapered from the bottom side to the top side.
Example 14 includes the method of example 13, wherein forming the first layer on top of the trench connector and the gate structure further includes applying a spacer to the walls of the first pillar and the second pillar.
Example 15 includes the method of example 14, wherein forming the first layer on top of the trench connector and the gate structure further includes: applying a layer of pre-metal dielectric (PMD) covering the first pillar and the second pillar; and etching a volume of the PMD above the gate and between the first pillar and the second pillar, wherein the volume is bounded by a surface of the gate and the spacer covering the walls of the first pillar and the spacer covering the walls of the second pillar.
Example 16 includes the method of example 15, wherein forming the first layer on top of the trench connector and the gate structure further includes removing the first pillar and the second pillar.
Example 17 includes the method of example 16, wherein forming the first layer on top of the trench connector and the gate structure further includes depositing a metal layer in contact with the surface of the gate, the top of the first trench connector, and the top of the second trench connector.
Example 18 includes the method of example 17, wherein forming the first layer on top of the trench connector and the gate structure further includes exposing the first trench connector, the second trench connector, and the first conductive via by planarizing the deposited metal layer.
Example 19 includes the method of any one of examples 12-18, wherein forming the second layer on top of the first layer further includes forming the second conductive via on a top surface of the first conductive via.
Example 20 includes the method of example 19, wherein forming the second conductive via further includes performing a metal direct etch.
