The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs. Each generation has smaller and more complex circuits than the previous generation.
Over the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometric size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling-down process generally provides benefits by increasing production efficiency and lowering associated costs.
However, these advances have increased the complexity of processing and manufacturing ICs. Since feature sizes continue to decrease, fabrication processes continue to become more difficult to perform. Therefore, it is a challenge to form reliable semiconductor devices at smaller and smaller sizes.
Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It should be noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
Further, spatially relative terms, such as “beneath,” “below.” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
Embodiments of the disclosure may relate to FinFET structure having fins and/or gate all around (GAA) transistor structures (which include channel layers suspended over a substrate, where the channel layers are fabricated from semiconductor layers stacks (i.e., fins)). The fins may be patterned using any suitable method. For example, the fins may be patterned using one or more photolithography processes, including double-patterning or multi-patterning processes. Generally, double-patterning or multi-patterning processes combine photolithography and self-aligned processes, allowing patterns to be created that have, for example, pitches smaller than what is otherwise obtainable using a single, direct photolithography process. For example, in some embodiments, a sacrificial layer is formed over a substrate and patterned using a photolithography process. Spacers are formed alongside the patterned sacrificial layer using a self-aligned process. The sacrificial layer is then removed, and the remaining spacers may then be used to pattern the fins. However, the fins may be formed using one or more other applicable processes.
Some embodiments of the disclosure are described. Additional operations can be provided before, during, and/or after the stages described in these embodiments. Some of the stages that are described can be replaced or eliminated for different embodiments. Additional features can be added to the semiconductor device structure. Some of the features described below can be replaced or eliminated for different embodiments. Although some embodiments are discussed with operations performed in a particular order, these operations may be performed in another logical order.
In some other embodiments, the semiconductor substrate 100 includes a compound semiconductor. For example, the compound semiconductor includes one or more III-V compound semiconductors having a composition defined by the formula AlX1GaX2InX3AsY1PY2NY3SbY4, where X1, X2, X3, Y1, Y2, Y3, and Y4 represent relative proportions. Each of them is greater than or equal to zero, and added together they equal 1. The compound semiconductor may include silicon carbide, gallium arsenide, indium arsenide, indium phosphide, one or more other suitable compound semiconductors, or a combination thereof. Other suitable substrate including II-VI compound semiconductors may also be used.
In some embodiments, the semiconductor substrate 100 is an active layer of a semiconductor-on-insulator (SOI) substrate. The SOI substrate may be fabricated using a separation by implantation of oxygen (SIMOX) process, a wafer bonding process, another applicable method, or a combination thereof. In some other embodiments, the semiconductor substrate 100 includes a multi-layered structure. For example, the semiconductor substrate 100 includes a silicon-germanium layer formed on a bulk silicon layer.
In some embodiments, a semiconductor stack having multiple semiconductor layers is formed over the semiconductor substrate 100. In some embodiments, the semiconductor stack includes multiple semiconductor layers 102a, 102b, 102c, and 102d. The semiconductor stack also includes multiple semiconductor layers 104a, 104b, 104c, and 104d. In some embodiments, the semiconductor layers 102a-102d and the semiconductor layers 104a-104d are laid out alternately. The semiconductor layers 102a-102d and the semiconductor layers 104a-104d have an alternating configuration.
In some embodiments, the semiconductor layers 102a-102d function as sacrificial layers that will be removed in a subsequent process to release the semiconductor layers 104a-104d. The semiconductor layers 104a-104d that are released may function as channel structures of one or more transistors.
In some embodiments, the semiconductor layers 104a-104d that will be used to form channel structures are made of a material that is different than that of the semiconductor layers 102a-102d. In some embodiments, the semiconductor layers 104a-104d are made of or include silicon, germanium, one or more other suitable materials, or a combination thereof. In some embodiments, the semiconductor layers 102a-102d are made of or include silicon germanium. In some other embodiments, the semiconductor layers 104a-104d are made of silicon germanium, and the semiconductor layers 102a-102d are made of silicon germanium with different atomic concentration of germanium than that of the semiconductor layers 104a-104d. As a result, different etching selectivity and/or different oxidation rates during subsequent processing may be achieved between the semiconductor layers 102a-102d and the semiconductor layers 104a-104d.
The present disclosure contemplates that the semiconductor layers 102a-102d and the semiconductor layers 104a-104d include any combination of semiconductor materials that can provide desired etching selectivity, desired oxidation rate differences, and/or desired performance characteristics (e.g., materials that maximize current flow).
In some embodiments, the semiconductor layers 102a-102d and 104a-104d are formed using multiple epitaxial growth operations. Each of the semiconductor layers 102a-102d and 104a-104d may be formed using a selective epitaxial growth (SEG) process, a chemical vapor deposition (CVD) process (e.g., a vapor-phase epitaxy (VPE) process, a low-pressure chemical vapor deposition (LPCVD) process, and/or an ultra-high vacuum CVD (UHV-CVD) process), a molecular beam epitaxy process, one or more other applicable processes, or a combination thereof.
In some embodiments, the semiconductor layers 102a-102d and 104a-104d are grown in-situ in the same process chamber. In some embodiments, the growth of the semiconductor layers 102a-102d and 104a-104d are alternately and sequentially performed in the same process chamber to complete the formation of the semiconductor stack. In some embodiments, the vacuum of the process chamber is not broken before the epitaxial growth of the semiconductor stack is accomplished.
Afterwards, hard mask elements are formed over the semiconductor stack to assist in a subsequent patterning of the semiconductor stack. Each of the hard mask elements may include a first mask layer 108 and a second mask layer 110. The first mask layer 108 and the second mask layer 110 may be made of different materials. One or more photolithography processes and one or more etching processes are used to pattern the semiconductor stack into multiple fin structures 106A and 106B, as shown in
The fin structures 106A and 106B may be patterned by any suitable method. For example, the fin structures 106A and 106B may be patterned using one or more photolithography processes, including double-patterning or multi-patterning processes. Double-patterning or multi-patterning processes may combine photolithography and self-aligned processes, allowing patterns to be created that have, for example, pitches smaller than what is otherwise obtainable using a single, direct photolithography process.
Each of the fin structures 106A and 106B may include portions of the semiconductor layers 102a-102d and 104a-104d and multiple semiconductor fins 101A and 101B, as shown in
As shown in
The spacer layer 202 may be made of or include silicon nitride, carbon-containing silicon nitride, silicon oxynitride, carbon-containing silicon oxynitride, silicon oxide, carbon-containing silicon oxide, one or more other suitable materials, or a combination thereof. The spacer layer 202 may be deposited using a CVD process, an atomic layer deposition (ALD) process, a CVD process, one or more other applicable processes, or a combination thereof.
As shown in
Afterwards, the patterned mask element 204 is removed, as shown in
In some embodiments, a sacrificial material layer 210 is deposited over the structure shown in
The sacrificial material layer 210 may be made of or include aluminum oxide, silicon nitride, one or more other suitable materials, or a combination thereof. The sacrificial material layer 210 may be deposited using a CVD process, an ALD process, a flowable chemical vapor deposition (FCVD) process, one or more other applicable processes, or a combination thereof. The sacrificial material layer 210 may be recessed using one or more etching processes. For example, a wet etching process is used to remove the upper portion of the sacrificial material layer 210, so as to recess the sacrificial material layer 210.
As shown in
As shown in
After the formation of the sacrificial structure 210′, the patterned mask element 212 is removed. As shown in
In some embodiments, one or more dielectric layers are deposited over the fin structures 106A and 106B and the sacrificial structure 210′. The dielectric layers may be made of or include silicon oxide, silicon oxynitride, borosilicate glass (BSG), phosphoric silicate glass (PSG), borophosphosilicate glass (BPSG), fluorinated silicate glass (FSG), low-k material, porous dielectric material, one or more other suitable materials, or a combination thereof. The dielectric layers may be deposited using a flowable chemical vapor deposition (FCVD) process, an atomic layer deposition (ALD) process, a chemical vapor deposition (CVD) process, one or more other applicable processes, or a combination thereof.
Afterwards, a planarization process is used to partially remove the dielectric layers. The hard mask elements (including the first mask layer 108 and the second mask layer 110) may also function as a stop layer of the planarization process. The planarization process may include a chemical mechanical polishing (CMP) process, a grinding process, a dry polishing process, an etching process, one or more other applicable processes, or a combination thereof.
Afterwards, one or more etching back processes are used to partially remove the dielectric layers. As a result, the remaining portion of the dielectric layers forms the isolation structure 214. Upper portions of the fin structures 106A and 106B protrude from the top surface of the isolation structure 214, as shown in
In some embodiments, the etching back process for forming the isolation structure 214 is carefully controlled to ensure that the topmost surface of the isolation structure 214 is positioned at a suitable height level, as shown in
Afterwards, the hard mask elements (including the first mask layer 108 and the second mask layer 110) are removed. Alternatively, in some other embodiments, the hard mask elements are removed or consumed during the planarization process and/or the etching back process that forms the isolation structure 214.
Afterwards, dummy gate stacks 120A and 120B are formed to extend across the fin structures 106A and 106B, as shown in
As shown in
As shown in
In some embodiments, a dummy gate dielectric material layer and a dummy gate electrode layer are sequentially deposited over the isolation structure 214 and the fin structures 106A and 106B. The dummy gate dielectric material layer may be deposited using an ALD process, a CVD process, one or more other applicable processes, or a combination thereof. The dummy gate electrode layer may be deposited using a CVD process. Afterwards, the dummy gate dielectric material layer and the dummy gate electrode layer are patterned to form the dummy gate stacks 120A and 120B.
In some embodiments, hard mask elements including mask layers 122 and 124 are used to assist in the patterning process for forming the dummy gate stacks 120A and 120B. With the hard mask elements as an etching mask, one or more etching processes are used to partially remove the dummy gate dielectric material layer and the dummy gate electrode layer. As a result, remaining portions of the dummy gate dielectric material layer and the dummy gate electrode layer form the dummy gate stacks 120A and 120B.
As shown in
In some embodiments, the spacer layers 126 and 128 are made of different materials. The spacer layer 126 may be made of a dielectric material that has a low dielectric constant. The spacer layer 126 may be made of or include silicon carbide, silicon oxycarbide, carbon-containing silicon oxynitride, silicon oxide, one or more other suitable materials, or a combination thereof. In some embodiments, the spacer layer 126 is a single layer. In some other embodiments, the spacer layer 126 includes multiple sub-layers. Some of the sub-layers may be made of different materials. Some of the sub-layers may be made of similar materials with different compositions. For example, one of the sub-layers may have a greater atomic concentration of carbon than other sub-layers.
The spacer layer 128 may be made of a dielectric material that can provide more protection to the gate stacks during subsequent processes. The spacer layer 128 may have a greater dielectric constant than that of the spacer layer 126. The spacer layer 128 may be made of silicon nitride, silicon oxynitride, carbon-containing silicon nitride, carbon-containing silicon oxynitride, one or more other suitable materials, or a combination thereof. The spacer layers 126 and 128 may be sequentially deposited using a CVD process, an ALD process, a physical vapor deposition (PVD) process, one or more other applicable processes, or a combination thereof.
However, embodiments of the disclosure are not limited thereto. Many variations and/or modifications can be made to embodiments of the disclosure. In some other embodiments, the spacer layers 126 and 128 are made of the same material. In some other embodiments, the spacer layer 128 is deposited before the spacer layer 126. In these cases, the spacer layer 128 is between the spacer layer 126 and the dummy gate electrode 118.
As shown in
Afterwards, the fin structures 106A and 106B are partially removed, in accordance with some embodiments. The portions of the fin structures 106A and 106B not covered by the dummy gate stacks 120A and 120B are recessed. As a result, the recesses 130 are formed, as shown in
One or more etching processes may be used to form the recesses 130. In some embodiments, a dry etching process is used to form the recesses 130. Alternatively, a wet etching process may be used to form the recesses 130. In some embodiments, the recesses 130 penetrate into the fin structure 106A. In some embodiments, the recesses 130 further extend into the semiconductor fin 101A, as shown in
In some embodiments, each of the recesses 130 has slanted sidewalls. Upper portions of the recesses 130 are larger (or wider) than lower portions of the recesses 130. In these cases, due to the profile of the recesses 130, the upper semiconductor layer (such as the semiconductor layer 104d) is shorter than the lower semiconductor layer (such as the semiconductor layer 104b).
However, embodiments of the disclosure have many variations. In some other embodiments, the recesses 130 have substantially vertical sidewalls. In these cases, due to the profile of the recesses 130, the upper semiconductor layer (such as the semiconductor layer 104d) is substantially as wide as the lower semiconductor layer (such as the semiconductor layer 104b).
Afterwards, as shown in
During the lateral etching of the semiconductor layers 102a-102d, the semiconductor layers 104a-104d may also be slightly etched. As a result, edge portions of the semiconductor layers 104a-104d are partially etched and thus shrink to become edge elements 105a-105d, as shown in
As shown in
The insulating layer 134 may be made of or include carbon-containing silicon nitride (SiCN), carbon-containing silicon oxynitride (SiOCN), carbon-containing silicon oxide (SiOC), silicon oxide, silicon nitride, one or more other suitable materials, or a combination thereof. The insulating layer 134 may be deposited using a CVD process. an ALD process, one or more other applicable processes, or a combination thereof.
As shown in
The inner spacers 136 cover the edges of the semiconductor layers 102a-102d. The inner spacers 136 may be used to prevent subsequently formed epitaxial structures (that function as, for example, source/drain structures) from being damaged during a subsequent process for removing the sacrificial layers 102a-102d. In some embodiments, the inner spacers 136 are made of a low-k material that has a lower dielectric constant than that of silicon oxide. In these cases, the inner spacers 136 may also be used to reduce parasitic capacitance between the subsequently formed source/drain structures and the gate stacks. As a result, the operation speed of the semiconductor device structure may be improved.
In some embodiments, after the etching process for forming the inner spacers 136, portions of the semiconductor fin 101A originally covered by the insulating layer 134 are exposed by the recesses 130, as shown in
As shown in
As mentioned above, some remaining portions of the spacer layers 126 and 128 form the support elements 216 and 218. The support elements 216 and 218 may be used to confine the formation of the epitaxial structures 138. As a result, the epitaxial structures 138 that have desired profile and size are formed.
In some embodiments, the epitaxial structures 138 connect to the semiconductor layers 104a-104d. Portions of the semiconductor layers 104a-104d that will be function as channel structures are sandwiched between two respective epitaxial structures 138, as shown in
In some embodiments, the epitaxial structures 138 are designed to function as source/drain structures of n-channel field-effect transistors (NFET). In these cases, the epitaxial structure 138 is n-type doped. In some embodiments, the epitaxial structures 138 is doped with one or more suitable n-type dopants. For example, the epitaxial structures 138 is a Si source/drain feature that is doped with phosphor (P), antimony (Sb), arsenic (As), or another suitable dopant.
Embodiments of the disclosure are not limited thereto. Many variations and/or modifications can be made to embodiments of the disclosure. In some other embodiments, the epitaxial structures 138 are designed to function as source/drain structures of p-channel field-effect transistors (PFET). In these cases, the epitaxial structure 138 is p-type doped. In some embodiments, the epitaxial structures 138 is doped with one or more suitable p-type dopants. For example, the epitaxial structures 138 is a SiGe source/drain feature or a Si source/drain feature that is doped with boron (B), gallium (Ga), indium (In), or another suitable dopant.
In some embodiments, the epitaxial structures 138 are formed using multiple epitaxial growth operations. In some embodiments, these epitaxial growth operations are performed in-situ in the same process chamber. In some embodiments, the vacuum of the process chamber is not broken before the formation of the epitaxial structures 138 is accomplished. The reaction gases may be varied in the reaction chamber during the epitaxial growth operations.
These epitaxial growth operations may be achieved using a selective epitaxial growth (SEG) process, a CVD process (e.g., a vapor-phase epitaxy (VPE) process, a low-pressure chemical vapor deposition (LPCVD) process, and/or an ultra-high vacuum CVD (UHV-CVD) process), a molecular beam epitaxy process, one or more other applicable processes, or a combination thereof. In some embodiments, the formation of the epitaxial structures 138 involves one or more etching processes that are used to fine-tune the shapes of the epitaxial structures 138.
In some embodiments, the epitaxial structures 138 are doped in-situ during their epitaxial growth. The initial reaction gas mixture for forming the epitaxial structures 138 contains respective dopants. In some embodiments, the epitaxial structures 138 are further exposed to one or more annealing processes to activate the dopants. For example, a rapid thermal annealing process is used. During the one or more annealing processes, the sacrificial structure 210′ remains stable.
Afterwards, as shown in
In some embodiments, an etch stop material layer and a dielectric material layer are sequentially deposited. The etch stop material layer may be deposited using a CVD process, an ALD process, a PVD process, one or more other applicable processes, or a combination thereof. The dielectric material layer may be deposited using an FCVD process, a CVD process, an ALD process, one or more other applicable processes, or a combination thereof.
Afterwards, a planarization process is used to partially remove the etch stop material layer and the dielectric material layer. As a result, the remaining portions of the etch stop material layer and the dielectric material layer respectively form the contact etch stop layer 139 and the dielectric layer 140, as shown in
As shown in
As shown in
Due to high etching selectivity, the semiconductor layers 104a-104d are slightly (or substantially not) etched. The remaining portions of the semiconductor layers 104a-104d form multiple semiconductor nanostructures 104a′-104d′. The semiconductor nanostructures 104a′-104d′ are constructed by or made up of the remaining portions of the semiconductor layers 104a-104d. The semiconductor nanostructures 104a′-104d′ may function as channel structures of transistors.
In some embodiments, the etchant used for removing the semiconductor layers 102a-102d also slightly removes the semiconductor layers 104a-104d that form the semiconductor nanostructures 104a′-104d′. As a result, the obtained semiconductor nanostructures 104a′-104d′ become thinner after the removal of the semiconductor layers 102a-102d. In some embodiments, each of the semiconductor nanostructures 104a′-104d′ is thinner than the edge portions 105a-105d since the edge portions 105a-105d are surrounded by other elements and thus are prevented from being reached and etched by the etchant.
After the removal of the semiconductor layers 102a-102d (that function as sacrificial layers), the recesses 144 are formed. The recesses 144 connect to the trench 142 and surround each of the semiconductor nanostructures 104a′-104d′. As shown in
During the removal of the semiconductor layers 102a-102d (that function as sacrificial layers), the inner spacers 136 protect the epitaxial structures 138 from being etched or damaged. The quality and reliability of the semiconductor device structure are improved.
As shown in
Each of the metal gate stacks 156A and 156B includes multiple metal gate stack layers. Each of the metal gate stacks 156A and 156B may include a gate dielectric layer 150 and a metal gate electrode 152. The metal gate electrode 152 may include one or more work function layers. The metal gate electrode 152 may further include a conductive filling. In some embodiments, the formation of the metal gate stacks 156A and 156B involves the deposition of multiple metal gate stack layers over the dielectric layer 140 to fill the trenches 142 and the recesses 144. The metal gate stack layers extend into the recesses 144 and are wrapped around each of the semiconductor nanostructures 104a′-104d′.
In some embodiments, the gate dielectric layer 150 is made of or includes a dielectric material with high dielectric constant (high-K). The gate dielectric layer 150 may be made of or include hafnium oxide, zirconium oxide, aluminum oxide, hafnium dioxide-alumina alloy, hafnium silicon oxide, hafnium silicon oxynitride, hafnium tantalum oxide, hafnium titanium oxide, hafnium zirconium oxide, one or more other suitable high-K materials, or a combination thereof. The gate dielectric layer 150 may be deposited using an ALD process, a CVD process, one or more other applicable processes, or a combination thereof.
In some embodiments, before the formation of the gate dielectric layer 150, interfacial layers are formed on the surfaces of the semiconductor nanostructures 104a′-104d′. The interfacial layers are very thin and are made of silicon oxide or germanium oxide, for example.
The work function layer of the metal gate electrode 152 may be used to provide the desired work function for transistors to enhance device performance including improved threshold voltage. In some embodiments, the work function layer is used for forming a PMOS device. The work function layer is a p-type work function layer. The p-type work function layer is capable of providing a work function value that is suitable for the device, which may be equal to or greater than about 4.8 eV.
The p-type work function layer may include metal, metal carbide, metal nitride, one or more other suitable materials, or a combination thereof. For example, the p-type metal includes tantalum nitride, tungsten nitride, titanium, titanium nitride, one or more other suitable materials, or a combination thereof.
In some embodiments, the work function layer is used for forming an NMOS device. The work function layer is an n-type work function layer. The n-type work function layer is capable of providing a work function value that is suitable for the device, which may be equal to or less than about 4.5 eV.
The n-type work function layer may include metal, metal carbide, metal nitride, or a combination thereof. For example, the n-type work function layer includes titanium nitride, tantalum, tantalum nitride, one or more other suitable materials, or a combination thereof. In some embodiments, the n-type work function is an aluminum-containing layer. The aluminum-containing layer may be made of or include TiAlC. TiAlO, TiAlN, one or more other suitable materials, or a combination thereof.
The work function layer may also be made of or include hafnium, zirconium, titanium, tantalum, aluminum, metal carbides (e.g., hafnium carbide, zirconium carbide, titanium carbide, aluminum carbide), aluminides, ruthenium, palladium, platinum, cobalt, nickel, conductive metal oxides, or a combinations thereof. The thickness and/or the compositions of the work function layer may be fine-tuned to adjust the work function level.
The work function layer may be deposited over the gate dielectric layer 150 using an ALD process, a CVD process, a PVD process, an electroplating process, an electroless plating process, one or more other applicable processes, or a combination thereof. In some embodiments, the formation of the work function layer involves one or more patterning processes. As a result, the p-type work function layer and the n-type work function layer are selectively formed over respective regions.
In some embodiments, a barrier layer is formed before the work function layer to interface the gate dielectric layer 150 with the subsequently formed work function layer. The barrier layer may also be used to prevent diffusion between the gate dielectric layer 150 and the subsequently formed work function layer. The barrier layer may be made of or include a metal-containing material. The metal-containing material may include titanium nitride, tantalum nitride, one or more other suitable materials, or a combination thereof. The barrier layer may be deposited using an ALD process, a CVD process, a PVD process, an electroplating process, an electroless plating process, one or more other applicable processes, or a combination thereof.
In some embodiments, the conductive fillings of the metal gate electrodes 152 are made of or include a metal material. The metal material may include tungsten, aluminum, copper, cobalt, one or more other suitable materials, or a combination thereof. A conductive layer used for forming the conductive filling may be deposited over the work function layer using a CVD process, an ALD process, a PVD process, an electroplating process, an electroless plating process, a spin coating process, one or more other applicable processes, or a combination thereof.
In some embodiments, a blocking layer is formed over the work function layer before the formation of the conductive layer used for forming the conductive filling. The blocking layer may be used to prevent the subsequently formed conductive layer from diffusing or penetrating into the work function layer. The blocking layer may be made of or include tantalum nitride, titanium nitride, one or more other suitable materials, or a combination thereof. The blocking layer may be deposited using an ALD process, a PVD process, an electroplating process, an electroless plating process, one or more other applicable processes, or a combination thereof.
Afterwards, a planarization process is performed to remove the portions of the metal gate stack layers outside of the trenches 142, in accordance with some embodiments. As a result, the remaining portions of the metal gate stack layers form the metal gate stacks 156A and 156B, as shown in
In some embodiments, the conductive filling does not extend into the recesses 144 since the recesses 144 are small and have been filled with other elements such as the gate dielectric layer 150 and the work function layer. However, embodiments of the disclosure are not limited thereto. In some other embodiments, a portion of the conductive filling extends into the recesses 144, especially for the lower recesses 144 that may have larger space.
Afterwards, as shown in
In some embodiments, the contact opening 220A further exposes the sacrificial structure 210, as shown in
As shown in
In some embodiments, a barrier layer is formed between the dielectric layer 140 and the conductive contacts 224A and 224B. The barrier layer may be made of or include tantalum nitride, titanium nitride, one or more other suitable materials, or a combination thereof. The thickness of the barrier layer may be within a range from about 0.5 nm to about 3 nm.
Metal-semiconductor compound layers 222 may be formed between the conductive contacts 224A and 224B and the epitaxial structures 138. The metal-semiconductor compound layers 222 may be used to improve electrical connections between the epitaxial structures 138 and the conductive contacts 224A and 224B. The metal-semiconductor compound layers 222 may be made of or include ruthenium silicide, titanium silicide, nickel silicide, titanium nickel silicide, cobalt silicide, titanium silicon germanium, one or more other suitable materials, or a combination thereof. The thickness of the metal-semiconductor compound layers 222 may be within a range from about 1 nm to about 6 nm. The formation of the Metal-semiconductor compound layers 222 and the conductive contacts 224A and 224B may involve one or more patterning processes, one or more deposition processes, one or more thermal annealing processes, and one or more planarization processes.
In some embodiments, the conductive contact 224A extends across the topmost surface and the bottommost surface of the epitaxial structure 138 thereunder, as shown in
As shown in
In some embodiments, a barrier layer is formed between the protective element 226 and the conductive vias 228A and 228B. The barrier layer may be made of or include tantalum nitride, titanium nitride, one or more other suitable materials, or a combination thereof. The thickness of the barrier layer may be within a range from about 0.5 nm to about 3 nm.
Afterwards, a dielectric layer 230 and conductive lines 232 are formed. In some embodiments, a damascene process is used to form the conductive lines 232. Afterwards, multiple dielectric layers, multiple conductive lines including conductive lines 236, and multiple conductive vias are formed. The conductive lines 236 may be top metal layers and may function as conductive pads. As a result, an interconnection structure 234 is formed. A barrier layer may be formed between the conductive features (including the conductive vias and the conductive lines) and the dielectric layers surrounding the conductive features. The barrier layer may be made of or include tantalum nitride, titanium nitride, ruthenium cobalt, one or more other suitable materials, or a combination thereof. The barrier layer may be a single layer or include two or more sub-layers. The thickness of the barrier layer may be within a range from about 1 nm to about 10 nm.
As shown in
As shown in
As shown in
As shown in
As shown in
In some embodiments, the conductive structure 246 includes a barrier layer that interfaces the spacer layer 208 and the isolation structure 214. The barrier layer may be made of or include tantalum nitride, titanium nitride, one or more other suitable materials, or a combination thereof. The barrier layer may have a thickness that is within a range from about 0.5 nm to about 3 nm.
In some embodiments, one or more conductive material layers are deposited over the semiconductor substrate 100 to overfill the trench 244. The conductive material layers may be deposited using a CVD process, a PVD process, an ALD process, an electroplating process, an electrochemical plating process, one or more other applicable processes, or a combination thereof. Since the semiconductor substrate 100 has been thinned, the aspect ratio of the trench 244 is within an acceptable range. The filling of the conductive material layer may thus be performed well.
Afterwards, a planarization process is used to remove the portions of the conductive material layers outside of the trench 244. As a result, the remaining portion of the conductive material layers forms the conductive structure 246. The planarization process may include a CMP process, a grinding process, an etching process, one or more other applicable processes, or a combination thereof.
As illustrated in embodiments shown in
The conductive structure 246 may have a height H that is within a range from about 50 nm to about 300 nm. The conductive structure 246 may have a width W that is within a range from about 20 nm to about 40 nm. The conductive structure 246 may have a length that is within a range from about 10 nm to about 1000 nm. After the formation of the conductive structure 246, the semiconductor substrate 100 that remains may have a thickness T that is within a range from about 50 nm to about 200 nm.
As shown in
Afterwards, a conductive feature 250 is formed in the dielectric layer 248, as shown in
A barrier layer may be formed between the conductive feature 250 and the dielectric layer 248. The barrier layer may be made of or include tantalum nitride, titanium nitride, one or more other suitable materials, or a combination thereof.
In some embodiments, one or more photolithography processes and one or more etching processes are used to form the opening used for containing the conductive feature 250. Afterwards, one or more conductive layers are deposited to fill the opening. A planarization process is then performed to remove the portions of the conductive layers outside of the opening. As a result, the remaining portions of the conductive layers form the conductive feature 250.
As shown in
Afterwards, a protective layer 260 and conductive bumps 262 are formed, as shown in
Many variations and/or modifications can be made to embodiments of the disclosure. The semiconductor nanostructures may have many applicable profiles. The semiconductor nanostructures may include nanosheets, nanowires, or other suitable nanostructures.
As shown in
Some embodiments relate to the GAA devices. However, embodiments of the disclosure are not limited thereto. Many variations and/or modifications can be made to embodiments of the disclosure. Some other embodiments may relate to planar transistor devices, FinFET devices, GAA devices including forksheets, one or more other applicable devices, or a combination thereof.
Embodiments of the disclosure form a semiconductor device structure with a backside conductive structure that may function as a power rail. A sacrificial structure is formed in a semiconductor substrate. The sacrificial structure is beside a fin structure and defines the position where the backside conductive structure will be formed. After the formation of the transistors, the semiconductor substrate is thinned to expose the sacrificial structure. Then, the sacrificial structure is replaced with a conductive structure that may function as a backside power rail. The conductive structure is self-aligned formed after the high temperature operations have been performed. No overlay shift and or any high temperature induced damage of the conductive structure would occur. The reliability and quality of the conductive structure are significantly improved.
In accordance with some embodiments, a method for forming a semiconductor device structure is provided. The method includes forming a first fin structure and a second fin structure over a substrate. The method also includes partially removing the substrate to form a trench between the first fin structure and the second fin structure and forming a sacrificial structure to fill the trench. The method further includes forming an epitaxial structure on the first fin structure and forming a conductive contact over the epitaxial structure and the sacrificial structure. In addition, the method includes replacing the sacrificial structure with a conductive structure.
In accordance with some embodiments, a method for forming a semiconductor device structure is provided. The method includes forming a fin structure over a substrate and forming a sacrificial structure beside the fin structure. A bottom surface of the fin structure is vertically between a top of the sacrificial structure and a bottom of the sacrificial structure. The method also includes forming an epitaxial structure on the fin structure and forming a conductive contact partially or completely covering the epitaxial structure and the sacrificial structure. The method further includes removing the sacrificial structure to form a trench exposing the conductive contact. In addition, the method includes forming a conductive structure in the trench.
In accordance with some embodiments, a semiconductor device structure is provided. The semiconductor device structure includes a semiconductor fin over a substrate and an epitaxial structure on the semiconductor fin. The semiconductor device structure also includes a conductive contact electrically connected to the epitaxial structure. The semiconductor device structure further includes a conductive structure extending from a bottom surface of the substrate towards the conductive contact. The conductive structure is electrically connected to the conductive contact.
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.