SEMICONDUCTOR DEVICE HAVING NANOSHEET TRANSISTOR AND METHODS OF FABRICATION THEREOF
Embodiments relate to a semiconductor device structure including a first channel layer having a first surface and a second surface, a second channel layer having a first surface and a second surface, and the first and second channel layers are formed of a first material. The structure also includes a first dopant suppression layer in contact with the second surface of the first channel layer, and a second dopant suppression layer parallel to the first dopant suppression layer. The second dopant suppression layer is in contact with the first surface of the second channel layer, and the first and second dopant suppression layers each comprises carbon or fluorine. The structure further includes a gate dielectric layer in contact with the first and second dopant suppression layers and the first surface of the first channel layer, and a gate electrode layer disposed on the gate dielectric layer.
This application is a divisional application of U.S. patent application Ser. No. 17/104,666 filed Nov. 25, 2020, which is incorporated by reference in its entirety.
BACKGROUNDThe semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry 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. Such scaling down presents new challenge. For example, transistors using nanowire channels have been proposed to improve carrier mobility and drive current in a device. N-type or p-type dopants are often used in highly doped source and drain regions to help reduce parasitic resistance of the transistors. As device size reduces, such dopants may propagate and result in poor mobility due to impurity scattering.
Therefore, there is a need to improve processing and manufacturing ICs.
Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is 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,” “over,” “on,” “top,” “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 present disclosure relate to gate all around (GAA) transistors, such as nanosheet FETs, which has a stack of semiconductor layers including first and second semiconductor layers alternatingly formed over a substrate. The first semiconductor layers form nanosheet channel(s) of the transistors. Portions of the second semiconductor layers are removed so that the first semiconductor layers in the nanosheet channels are wrapped around by a gate electrode for better gate control. According to embodiments of the present disclosure, exposed surfaces of the first semiconductor layers are covered by a dopant suppression layer to prevent dopant diffusion from source/drain regions into the nanosheet channels.
While the embodiments of this disclosure are discussed with respect to nanosheet channel FETs, implementations of some aspects of the present disclosure may be used in other processes and/or in other devices, such as planar FETs, Fin-FETs, Horizontal Gate All Around (HGAA) FETs, Vertical Gate All Around (VGAA) FETs, and other suitable devices. A person having ordinary skill in the art will readily understand other modifications that may be made are contemplated within the scope of this disclosure. In cases where gate all around (GAA) transistor structures are adapted, the GAA transistor structures may be patterned by any suitable method. For example, the structures 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 one embodiment, 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 GAA structure.
The substrate 101 may include various regions that have been doped with impurities (e.g., dopants having p-type or n-type conductivity). Depending on circuit design, the dopants may be, for example boron for an p-type field effect transistor (PFET) and phosphorus for a n-type field effect transistor (NFET).
The stack of layers 104 includes alternating semiconductor layers made of different materials to facilitate formation of nanosheet channels in a multi-gate device, such as nanosheet channel FETs. In some embodiments, the stack of layers 104 includes first semiconductor layers 106 (106a-106c) and second semiconductor layers 108 (108a-108c). In some embodiments, the stack of layers 104 includes alternating first and second semiconductor layers 106, 108. The first semiconductor layers 106 are aligned with the second semiconductor layers 108. The first semiconductor layers 106 and the second semiconductor layers 108 are made of semiconductor materials having different etch selectivity and/or oxidation rates. For example, the first semiconductor layers 106 may be made of Si and the second semiconductor layers 108 may be made of SiGe. In some examples, the first semiconductor layers 106 may be made of SiGe and the second semiconductor layers 108 may be made of Si. In some cases, the SiGe in the first or second semiconductor layers 106, 108 can have a germanium composition percentage between about 10% and about 50%. Alternatively, in some embodiments, either of the semiconductor layers 106, 108 may be or include other materials such as Ge, SiC, GeAs, GaP, InP, InAs, InSb, GaAsP, AlinAs, AlGaAs, InGaAs, GaInP, GaInAsP, or any combinations thereof.
The first semiconductor layers 106 or portions thereof may form nanosheet channel(s) of the semiconductor device structure 100 in later fabrication stages. The term nanosheet is used herein to designate any material portion with nanoscale, or even microscale dimensions, and having an elongate shape, regardless of the cross-sectional shape of this portion. Thus, this term designates both circular and substantially circular cross-section elongate material portions, and beam or bar-shaped material portions including, for example, a cylindrical in shape or substantially rectangular cross-section. The nanosheet channel(s) of the semiconductor device structure 100 may be surrounded by a gate electrode. The semiconductor device structure 100 may include a nanosheet transistor. The nanosheet transistors may be referred to as nanowire transistors, gate-all-around (GAA) transistors, multi-bridge channel (MBC) transistors, or any transistors having the gate electrode surrounding the channels.
The stack of layers 104 also includes a plurality of dopant suppression layers 103 (103a-f) formed over the front side of the substrate 101. It has been observed that dopants such as phosphorus or arsenic may diffuse from subsequently formed source and drain (S/D) regions into the nanosheet channels (e.g., first semiconductor layers 106) along the heterojunction (e.g., the interface of Si/SiGe layers). Diffusion of dopants into the nanosheet channels results in leakage current at or near the heterojunction, thereby degrading the performance of the semiconductor device structure 100. The dopant suppression layers 103 (e.g., dopant suppression layers 103b, 103c as shown below in
In some embodiments, one or more dopant suppression layers 103 are disposed between the first semiconductor layer 106 and the second semiconductor layer 108. In the embodiment shown in
In various embodiments, the dopant suppression layers 103 may be or include a silicon-containing layer or a carbon-containing layer. Exemplary materials may include, but are not limited to, silicon carbide, carbon doped silicon, silicon carbonitride (nitride-bonded silicon carbide or silicon carbide doped with nitrogen), or any suitable material that contains at least the elements silicon and carbon. Carbon doped silicon or the like is advantageous for minimizing dopant diffusion because carbon tends to trap silicon vacancies, which in turn reduces the silicon interstitial concentrations available for bonding with dopants (e.g., boron or phosphorous) in silicon-based materials. In addition, since the carbon doped silicon have greater lattice constant than that of the silicon-based first semiconductor layers 106, the dopant suppression layers 103 can produce tensile strained nanosheet channels (e.g., n-channel FET), which in turn enhances electron mobility of the semiconductor structure device 100.
In one embodiment, the dopant suppression layer 103 is silicon carbide. In another embodiment, the dopant suppression layer 103 is carbon doped silicon. In either case, the dopant suppression layers 103 may have a carbon atomic concentration (at. %) in a range between about 0.1 at. % and about 3 at. %. If the carbon concentration exceeds over 3 at. %, defects such as dislocations may occur at or near the interface between the dopant suppression layers 103 and the layers the dopant suppression layers 103 abutting against thereto (e.g., first and second semiconductor layers 106, 108) due to lattice mismatch. On the other hand, if the carbon concentration is less than 0.1 at. %, the dopant suppression layers 103 may not be sufficient to trap silicon vacancies and reduce the silicon interstitial concentrations available for bonding with dopants. As a result, the dopant suppression layers 103 may fail to block or minimize unwanted dopant diffusion coming from the source and drain regions.
In some embodiments, the dopant suppression layers 103 may be or include arsenic doped silicon carbide, arsenic doped silicon, or any suitable material containing at least the elements silicon and arsenic, which may contain one or more additional elements, such as carbon. In one embodiment, the dopant suppression layer 103 is arsenic doped silicon carbide. In another embodiment, the dopant suppression layer 103 is arsenic doped silicon. In either case, the dopant suppression layers 103 may be doped with arsenic at a level of about 1×1018 atoms per cubic centimeter (atoms/cm3) or less.
In some embodiments, the dopant suppression layer 103 may be or include fluorine doped silicon. In one embodiment, the dopant suppression layer 103 is silicon fluoride or any suitable material containing at least the elements silicon and fluorine. In another embodiment, the dopant suppression layer 103 is fluorine-rich silicon. In such a case, the dopant suppression layers 103 may be doped with fluorine at a level of about 1x1018 atoms per cubic centimeter (atoms/cm3) or less.
The first and second semiconductor layers 106, 108 are formed by any suitable deposition process, such as epitaxy. By way of example, epitaxial growth of the layers of the stack of layers 104 may be performed by a molecular beam epitaxy (MBE) process, a metalorganic chemical vapor deposition (MOCVD) process, and/or other suitable epitaxial growth processes. The dopant suppression layers 103 may be formed by chemical vapor deposition (CVD) process, physical vapor deposition (PVD), or any suitable deposition process.
Each first semiconductor layer 106 may have a thickness in a range between about 5 nm and about 30 nm. Each second semiconductor layer 108 may have a thickness that is equal, less, or greater than the thickness of the first semiconductor layer 106. In some embodiments, each second semiconductor layer 108 has a thickness in a range between about 2 nm and about 50 nm. Each dopant suppression layer 103 may have a thickness of about 3 nm or less, for example about 0.1 nm to about 1.5 nm. While three first semiconductor layers 106 and three second semiconductor layers 108 are illustrated in
In
In
In
In
The sacrificial gate dielectric layer 132 may include one or more layers of dielectric material, such as a silicon oxide-based material. The sacrificial gate electrode layer 134 may include silicon such as polycrystalline silicon or amorphous silicon. The mask layer 136 may include more than one layer, such as an oxide layer and a nitride layer. The gate spacer 138 may be made of a dielectric material such as silicon oxide, silicon nitride, silicon carbide, silicon oxynitride, SiCN, silicon oxycarbide, SiOCN, and/or combinations thereof.
The portions of the fin structures 112 that are covered by the sacrificial gate electrode layer 134 of the sacrificial gate structure 130 serve as channel regions for the semiconductor device structure 100. The fin structures 112 that are partially exposed on opposite sides of the sacrificial gate structure 130 define source/drain (S/D) regions for the semiconductor device structure 100. In some cases, some S/D regions may be shared between various transistors. For example, various one of the S/D regions may be connected together and implemented as multiple functional transistors. It should be understood that the source region and the drain region can be interchangeably used since the epitaxial features to be formed in these regions are substantially the same.
In
After removing edge portions of each second semiconductor layers 108, a dielectric layer (or so-called inner spacer) is deposited in the cavities to form dielectric spacers 144. The dielectric spacers 144 are in contact with portions of the dopant suppression layers 103, as shown in
In one example shown in
The epitaxial S/D features 146 may grow both vertically and horizontally to form facets, which may correspond to crystalline planes of the material used for the substrate 101. In some cases, the epitaxial S/D features 146 of a fin structure may grow and merge with the epitaxial S/D features 146 of the neighboring fin structures, as one example shown in
In some embodiments, the gate dielectric layer 170 includes an interfacial layer (IL) 148 and a high-K (HK) dielectric layer 150.
The HK dielectric layer 150 may include or made of one or more layers of a dielectric material, such as silicon oxide, silicon nitride, or high-K dielectric material. Examples of HK dielectric material 150 may include, but are not limited to, hafnium oxide (HfO2), hafnium silicate (HfSiO), hafnium silicon oxynitride (HfSiON), hafnium aluminum oxide (HfAlO), hafnium lanthanum oxide (HfLaO), hafnium zirconium oxide (HfZrO), hafnium tantalum oxide (HMO), hafnium titanium oxide (HfTiO), lanthanum oxide (LaO), aluminum oxide (AlO), aluminum silicon oxide (AlSiO), zirconium oxide (ZrO), titanium oxide (TiO), tantalum oxide (Ta2O5), yttrium oxide (Y2O3), silicon oxynitride (SiON), hafnium dioxide-alumina (HfO2-Al2O3) alloy, or other suitable high-k materials. The HK dielectric layer 150 may be a conformal layer formed by a conformal process, such as an ALD process or a CVD process.
The gate electrode layer 172 may include one or more layers of conductive material, such as polysilicon, aluminum, copper, titanium, tantalum, tungsten, cobalt, molybdenum, tantalum nitride, nickel silicide, cobalt silicide, TiN, WN, TiAl, TiAlN, TaCN, TaC, TaSiN, metal alloys, other suitable materials, and/or any combinations thereof. The gate electrode layer 172 may be formed by CVD, ALD, electro-plating, or other suitable deposition technique. The gate electrode layer 172 may be also deposited over the upper surface of the ILD layer 164. The gate dielectric layer 170 and the gate electrode layer 172 formed over the ILD layer 164 are then removed by using, for example, CMP, until the top surface of the ILD layer 164 is exposed.
After the formation of the contact openings, a silicide layer 178 is formed on the epitaxial S/D features 146. The silicide layer 178 conductively couples the epitaxial S/D features 146 to the subsequently formed S/D contacts 176. The silicide layer 178 may be formed by depositing a metal source layer over the epitaxial S/D features 146 and performing a rapid thermal annealing process. During the rapid anneal process, the portion of the metal source layer over the epitaxial S/D features 146 reacts with silicon in the epitaxial S/D features 146 to form the silicide layer 178. Unreacted portion of the metal source layer is then removed. For n-channel FETs, the silicide layer 178 may be made of a material including one or more of TiSi , CrSi, TaSi, MoSi, ZrSi, HfSi , ScSi, Ysi, HoSi, TbSI, GdSi, LuSi, DySi, ErSi, YbSi, or combinations thereof. For p-channel FETs, the silicide layer 178 may be made of a material including one or more of NiSi, CoSi, MnSi, Wsi, FeSi, RhSi, PdSi, RuSi, PtSi, IrSi, OsSi, or combinations thereof. In some embodiments, the silicide layer 178 is made of a metal or metal alloy silicide, and the metal includes a noble metal, a refractory metal, a rare earth metal, alloys thereof, or combinations thereof. Next, a conductive material is formed in the contact openings and form the S/D contacts 176. The conductive material may be made of a material including one or more of Ru, Mo, Co, Ni. W, Ti, Ta, Cu, Al, TiN and TaN. While not shown, a barrier layer (e.g., TiN, TaN, or the like) may be formed on sidewalls of the contact openings prior to forming the S/D contacts 176. Then, a planarization process, such as CMP, is performed to remove excess deposition of the contact material and expose the top surface of the gate electrode layer 172.
It is understood that the semiconductor device structure 100 may undergo further complementary metal oxide semiconductor (CMOS) and/or back-end-of-line (BEOL) processes to form various features such as transistors, contacts/vias, interconnect metal layers, dielectric layers, passivation layers, etc. The semiconductor device structure 100 may also include backside contacts (not shown) on the backside of the substrate 101 so that either source or drain of the epitaxial S/D features 146 is connected to a backside power rail (e.g., positive voltage VDD or negative voltage VSS) through the backside contacts.
The extended dopant suppression layer 103g may be formed on the first semiconductor layers 106 by a selective deposition process, such as selective ALD process. The selective ALD process allows the extended dopant suppression layer 103g to be selectively deposited on the exposed surfaces of the first semiconductor layers 106 relative to the sidewall of the gate spacers 138 and the dielectric spacers 144. The extended dopant suppression layer 103g may also form on the dopant suppression layers 103a-103f. The extended dopant suppression layer 103g may have the same thickness as the dopant suppression layer 103.
Suitable materials for the extended dopant suppression layer 103h may include, but are not limited to, a silicon-containing layer or a carbon-containing layer, such as silicon carbide, carbon doped silicon, silicon carbonitride (nitride-bonded silicon carbide or silicon carbide doped with nitrogen), or any suitable material that contains at least the elements silicon and carbon; arsenic doped silicon carbide, arsenic doped silicon, or any suitable material containing at least the elements silicon and arsenic, which may contain one or more additional elements, such as carbon; and fluorine-rich silicon, such as silicon fluoride or any suitable material containing at least the elements silicon and fluorine.
After the formation of the extended dopant suppression layers 103g (
While three first semiconductor layers 206 and three second semiconductor layers 208 are illustrated in
The stack of layers 204 also includes a plurality of dopant suppression layers 203 (203a-d) formed over the front side of the substrate 101. The dopant suppression layers 203 can be formed from the same material as the dopant suppression layers 103, such as silicon carbide, carbon doped silicon, arsenic doped silicon carbide, or fluorine-rich silicon, etc., as discussed in various embodiments above. In some embodiments, one or more dopant suppression layers 203 are formed in the first semiconductor layer 206. Stated differently, each first semiconductor layer 206a, 206b, 206c has an upper portion and a lower portion, and the dopant suppression layer 203a, 203b, 203c is sandwiched between the upper portion and the lower portion of each of the first semiconductor layers 206a, 206b, 206c, respectively. In the embodiment shown in
In some embodiments, the extended dopant suppression layer 203g is formed from a material different than that of the dopant suppression layer 203 (e.g., 203a-203d), such as the material used for the extended dopant suppression layer 103h discussed above in
Likewise, the extended dopant suppression layer 203g may be formed on the first semiconductor layers 206 by a selective deposition process, such as selective ALD process used for forming the extended dopant suppression layer 103g. The extended dopant suppression layer 203g may also form on the dopant suppression layers 203a-203d. The extended dopant suppression layer 203g may have the same thickness as the dopant suppression layer 103g.
After the formation of the extended dopant suppression layers 203g, the semiconductor device structure 200 is subjected to various processes, as discussed above with respect to
In
As can be seen in
The extended dopant suppression layers 203g prevent or at least minimize diffusion of dopants from the epitaxial S/D features 246 into the nanosheet channels (e.g., first semiconductor layers 206a, 206b). The extended dopant suppression layers 203g also help confine the dopants at the edge of the epitaxial S/D features 246 near the nanosheet channels (e.g., regions near and along the extended dopant suppression layer 203g and the dielectric spacers 244), thereby forming lightly doped source and drain region. The lightly doped source and drain region minimizes hot electron injection into the gate and improves the speed and reliability of the semiconductor device structure 200.
Embodiments of the present disclosure provide a semiconductor device structure having exposed surfaces of nanosheet channels covered by a dopant suppression layer to prevent dopant diffusion from source/drain (S/D) features into the nanosheet channels, which in turn mitigates electron mobility degradation. The dopant suppression layer also confines the dopants at the interface between the S/D features and the nanosheet channels, which improves S/D junction abruptness and reduces contact resistance at or near the nanosheet channels. Reduction of dopants in the nanosheet channels allows for fuller depletion in the nanosheet channels and results in less short-channel effects due to steeper sub-threshold current swing (SS) and smaller drain induced barrier lowering (DIBL). In addition, dopant suppression layers using carbon doped silicon also produce tensile strained nanosheet channels, which in turn enhances electron mobility of the semiconductor structure device.
An embodiment is a semiconductor device structure. The structure includes a first channel layer having a first surface and a second surface opposing the first surface, a second channel layer having a first surface and a second surface opposing the first surface of the second channel layer, and the first and second channel layers are formed of a first material. The structure also includes a first dopant suppression layer in contact with the second surface of the first channel layer, and a second dopant suppression layer parallel to the first dopant suppression layer. The second dopant suppression layer is in contact with the first surface of the second channel layer, and the first and second dopant suppression layers each comprises carbon or fluorine. The structure further includes a gate dielectric layer in contact with the first and second dopant suppression layers and the first surface of the first channel layer, and a gate electrode layer disposed on the gate dielectric layer.
Another embodiment is a semiconductor device structure. The structure includes a first channel layer formed of a first material, the first channel layer includes a first portion and a second portion, wherein the first portion has a first surface, a second surface opposing the first surface, a third surface, and a fourth surface opposing the third surface. The first surface connects the third surface to the fourth surface, and the second surface connects the third surface to the fourth surface. The second portion has a first surface, a second surface opposing the first surface of the second portion, a third surface, and a fourth surface opposing the third surface of the second portion. The surface of the second portion connects the third surface to the fourth surface of the second portion, and the second surface of the second portion connects the third surface to the fourth surface of the second portion. The structure also includes a dopant suppression layer. The dopant suppression layer includes a first part in contact with the second surface of the first portion and the first surface of the second portion, a second part connecting to the first part and in contact with the third surface of the first portion and the third surface of the second portion, and a third part connecting to the first part and in contact with the fourth surface of the first portion and the fourth surface of the second portion. The first part, the second part, and the third part form a shape of a capital “H” with respect to a cross-sectional view of the semiconductor device structure. The structure further includes a gate dielectric layer in contact with the first surface of the first portion and the second surface of the second portion, and a gate electrode layer disposed on the gate dielectric layer.
A further embodiment is a semiconductor device structure. The structure includes a first channel layer formed of a first semiconductor material, a second channel layer disposed adjacent and in parallel to the first channel layer, the second channel layer being formed of the first semiconductor material, a first dopant suppression layer in contact with sidewalls and a bottom surface of the first channel layer, a second dopant suppression layer in contact with sidewalls and top and bottom surfaces of the second channel layer, wherein the first and second dopant suppression layers each comprises carbon or fluorine, a gate dielectric layer in contact with the first and second dopant suppression layers, and a gate electrode layer disposed on the gate dielectric layer to surround portions of the first and second channel layers.
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.
Claims
1. A semiconductor device structure, comprising:
- a first channel layer having a first surface and a second surface opposing the first surface, the first channel layer being formed of a first material;
- a second channel layer having a first surface and a second surface opposing the first surface of the second channel layer, the second channel layer being formed of the first material;
- a first dopant suppression layer in contact with the second surface of the first channel layer;
- a second dopant suppression layer parallel to the first dopant suppression layer, the second dopant suppression layer being in contact with the first surface of the second channel layer, wherein the first and second dopant suppression layers each comprises carbon or fluorine;
- a gate dielectric layer in contact with the first dopant suppression layer, the second dopant suppression layer, and the first surface of the first channel layer; and
- a gate electrode layer disposed on the gate dielectric layer.
2. The semiconductor device structure of claim 1, wherein each of the first dopant suppression layer and the second dopant suppression layer further comprises silicon, arsenic, or a combination thereof.
3. The semiconductor device structure of claim 2, wherein the first dopant suppression layer and the second dopant suppression layer are silicon carbide, carbon doped silicon, or arsenic doped silicon carbide.
4. The semiconductor device structure of claim 1, further comprising:
- a first source/drain feature in contact with the first dopant suppression layer and the second dopant suppression layer; and
- a second source/drain feature in contact with the first dopant suppression layer and the second dopant suppression layer.
5. The semiconductor device structure of claim 1, further comprising:
- a third dopant suppression layer in contact with a third surface of the first channel layer, the third surface connecting the first surface to the second surface of the first channel layer; and
- a fourth dopant suppression layer in contact with a fourth surface of the first channel, the fourth surface opposing the third surface, and the fourth surface connecting the first surface to the second surface of the first channel layer.
6. The semiconductor device structure of claim 5, wherein the third and fourth dopant suppression layers are formed of the same material as the first dopant suppression layer.
7. The semiconductor device structure of claim 5, wherein the third and fourth dopant suppression layers are in contact with the first dopant suppression layer.
8. The semiconductor device structure of claim 5, further comprising:
- a first source/drain feature in contact with the third dopant suppression layer; and
- a second source/drain feature in contact with the fourth dopant suppression layer.
9. The semiconductor device structure of claim 8, further comprising:
- a fifth dopant suppression layer in contact with the second surface of the second channel layer.
10. The semiconductor device structure of claim 9, further comprising:
- a sixth dopant suppression layer disposed between and in contact with the second channel layer and the first source/drain feature; and
- a seventh dopant suppression layer disposed between and in contact with the second channel layer and the second source/drain feature,
- wherein the sixth and seventh dopant suppression layers are formed of the same material as the third and fourth dopant suppression layers.
11. The semiconductor device structure of claim 10, wherein the second dopant suppression layer, the fifth dopant suppression layer, the sixth dopant suppression layer, and the seventh dopant suppression layer surround and in contact with the second channel layer.
12. A semiconductor device structure, comprising:
- a first channel layer formed of a first material, the first channel layer comprising a first portion and a second portion, wherein the first portion has a first surface, a second surface opposing the first surface, a third surface, and a fourth surface opposing the third surface, the first surface connecting the third surface to the fourth surface, and the second surface connecting the third surface to the fourth surface, and wherein the second portion has a first surface, a second surface opposing the first surface of the second portion, a third surface, and a fourth surface opposing the third surface of the second portion, wherein the first surface of the second portion connecting the third surface to the fourth surface of the second portion, and the second surface of the second portion connecting the third surface to the fourth surface of the second portion;
- a dopant suppression layer, comprising: a first part in contact with the second surface of the first portion and the first surface of the second portion; a second part connecting to the first part and in contact with the third surface of the first portion and the third surface of the second portion; and a third part connecting to the first part and in contact with the fourth surface of the first portion and the fourth surface of the second portion, wherein the first part, the second part, and the third part form a shape of a capital “H” with respect to a cross-sectional view of the semiconductor device structure;
- a gate dielectric layer in contact with the first surface of the first portion and the second surface of the second portion; and
- a gate electrode layer disposed on the gate dielectric layer.
13. The semiconductor device structure of claim 12, wherein the dopant suppression layer comprises carbon or fluorine.
14. The semiconductor device structure of claim 13, wherein the dopant suppression layer further comprises silicon, arsenic, or a combination thereof.
15. The semiconductor device structure of claim 14, wherein the dopant suppression layer is silicon carbide, carbon doped silicon, or arsenic doped silicon carbide.
16. The semiconductor device structure of claim 13, further comprising:
- a first source/drain feature in contact with the second part of the dopant suppression layer; and
- a second source/drain feature in contact with the third part of the dopant suppression layer.
17. The semiconductor device structure of claim 13, further comprising:
- a second channel layer formed of the first material, wherein the second channel layer is aligned with the first channel layer and in contact with the gate dielectric layer.
18. A semiconductor device structure, comprising:
- a first channel layer formed of a first semiconductor material;
- a second channel layer disposed adjacent and in parallel to the first channel layer, the second channel layer being formed of the first semiconductor material;
- a first dopant suppression layer in contact with sidewalls and a bottom surface of the first channel layer;
- a second dopant suppression layer in contact with sidewalls and top and bottom surfaces of the second channel layer, wherein the first and second dopant suppression layers each comprises carbon or fluorine;
- a gate dielectric layer in contact with the first and second dopant suppression layers; and
- a gate electrode layer disposed on the gate dielectric layer to surround portions of the first and second channel layers.
19. The semiconductor device structure of claim 18, wherein each of the first dopant suppression layer and the second dopant suppression layer further comprises silicon, arsenic, or a combination thereof.
20. The semiconductor device structure of claim 18, wherein the second dopant suppression layer contacting the sidewalls of the first channel comprises a first material, and the first dopant suppression layer contacting the top and bottom surfaces comprises a second material that is chemically different from the first material.
Type: Application
Filed: Jul 27, 2022
Publication Date: Nov 17, 2022
Inventors: Chih-Ching Wang (Kinmen County), Wen-Hsing Hsieh (Hsinchu), Jon-Hsu Ho (New Taipei City), Wen-Yuan Chen (Taoyuan County), Chia-Ying Su (Hsinchu), Chung-Wei Wu (Hsinchu County), Zhiqiang Wu (Hsinchu County)
Application Number: 17/875,221