Methods for depositing boron-doped silicon germanium layers and related compositions

Abstract

Methods and related compositions for depositing boron doped silicon germanium layers are disclosed. The method includes depositing a boron-doped silicon germanium layer by a thermal deposition process employing a composition comprising an iodosilane precursor. The method further includes depositing a boron-doped silicon germanium layer by a selective deposition process.

Description

Technical Field

[0001] The present disclosure generally relates to the field of semiconductor processing methods and related structures and compositions, and to the field of device and integrated circuit manufacturing. In particular, the present disclosure generally relates to methods for depositing boron-doped silicon germanium layers and related compositions employed during the deposition process. Background Art

[0002] Silicon germanium (SiGe) layers are increasingly used in semiconductor devices, in part because such high mobility layers improve device performance, speed, power consumption, and breakdown electric field compared to similar devices fabricated with lower mobility semiconductors such as silicon.

[0003] A variety of deposition processes can be used for the deposition of silicon germanium layers, including, for example, chemical vapor deposition, molecular beam epitaxy, and physical vapor deposition. In particular, epitaxial deposition processes can be used to deposit single-crystalline silicon germanium layers. The deposition of silicon germanium layers can also include doping these layers with selected impurities to improve / control the electrical characteristics of the layers. For example, by incorporating boron into the SiGe layer, the SiGe layer can be doped p-type.

[0004] However, with increasing device density and decreasing substrate area, there is a need to improve the deposition methods and related gas compositions for depositing silicon germanium layers in order to maintain or even improve device / integrated circuit performance. Accordingly, in order to be able to deposit enhanced silicon germanium layers, improved deposition methods and related deposition gas compositions are needed.

[0005] Any discussion set forth in this section, including discussions of problems and solutions, has been included in the present disclosure merely to provide background for the present disclosure. Such discussion should not be construed as an admission that any or all of the information was known or constituted prior art at the time the invention was made. Summary of the Invention

[0006] This summary of the invention introduces some concepts in a simplified form that will be further described in detail below. This summary of the invention is not necessarily intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0007] Various embodiments of the present disclosure relate to methods and related gas compositions for thermally depositing boron-doped silicon germanium layers having a high active dopant concentration and a high germanium content. As will be described in more detail below, the methods and related compositions described herein are capable of depositing boron-doped silicon germanium layers having a high active dopant concentration and a high germanium content.

[0008] According to an example of the present disclosure, a method for thermally depositing a boron-doped silicon germanium layer with a high active dopant concentration and a high germanium content is provided. In such an example, the method includes placing a substrate in a reaction chamber, heating the substrate to a deposition temperature, and depositing a boron-doped silicon germanium layer on the surface of the substrate through an epitaxial deposition process. In such an example, the epitaxial deposition process includes introducing a germanium precursor into the reaction chamber, introducing a boron precursor into the reaction chamber, and introducing a silicon precursor including an iodosilane precursor into the reaction chamber. According to an example of the present disclosure, the deposition temperature is between 250 °C and 400 °C. In such an example, the boron-doped silicon germanium layer is deposited at a growth rate between 1 nm / min and 10 nm / min, and the average layer thickness is between 5 nm and 20 nm. According to an example of the present disclosure, the germanium precursor includes a germanium chloride compound selected from GeCl 4 、GeCl 2 and GeCl 2 H 2 . According to an example of the present disclosure, the boron precursor includes a boron chloride compound selected from BH 2 Cl, BCl 2 H and BCl 3 . According to an example of the present disclosure, the iodosilane precursor is selected from moniodosilane, diiodosilane, triiodosilane, and tetraiodosilane. According to an example of the present disclosure, the iodosilane precursor consists of diiodosilane. According to an example of the present disclosure, the iodosilane precursor consists of moniodosilane. According to an example of the present disclosure, the substrate includes a silicon germanium source / drain region, and the boron-doped silicon germanium layer is directly epitaxially deposited on the silicon germanium source / drain region. According to an example of the present disclosure, the boron-doped silicon germanium layer has an active dopant concentration greater than 3×10 21 cm -3 and a germanium content greater than 50 atomic %. According to an example of the present disclosure, the epitaxial deposition process is a selective deposition process that selectively deposits a boron-doped silicon germanium layer on surface A relative to surface B. In such an example, surface A is a silicon nitride surface and surface B is a silicon oxide surface, or surface A is a silicon oxide surface or a silicon nitride surface and surface B is a silicon surface. In such an example, the method further includes introducing an etchant into the reaction chamber. In such an example, the selective deposition process further includes a cyclic deposition process or a cyclic deposition-etching process.

[0009] According to an additional example of the present disclosure, a method for forming a contact layer to a silicon germanium source / drain region is provided. In such an example, the method includes placing a substrate in a reaction chamber, the substrate including one or more silicon germanium source / drain regions, and heating the substrate to a deposition temperature between 250 °C and 400 °C. In such an example, the method includes depositing a boron-doped silicon germanium layer on the silicon germanium source / drain region through an epitaxial deposition process by introducing a single silicon precursor including an iodosilane precursor, a germanium precursor, and a boron precursor into the reaction chamber. In such an example, the boron-doped silicon germanium layer has an active dopant concentration greater than 3×10 21cm -3 An active dopant concentration of and a germanium content greater than 50 atomic %. According to an example of the present disclosure, at least one of the germanium precursor and the boron precursor includes a chloride compound. According to an example of the present disclosure, the epitaxial deposition process is a selective deposition process that selectively deposits a boron-doped silicon-germanium layer on surface A relative to surface B. In such an example, surface A is a silicon nitride surface, surface B is a silicon oxide surface, or surface A is a silicon oxide surface or a silicon nitride surface, and surface B is a silicon surface. According to an example of the present disclosure, the iodosilane precursor consists of diiodosilane or monoiodosilane.

[0010] According to an additional example of the present disclosure, there is provided a composition for epitaxially depositing a boron-doped silicon-germanium layer having an active dopant concentration of greater than 3×10 21 cm -3 and a germanium content greater than 50 atomic %. In such an example, the composition includes an iodosilane precursor having less than 1% metal impurities and less than 1% phosphorus impurities. In some embodiments, the composition consists essentially of an iodosilane precursor, a germanium precursor, a boron precursor, and one or more additional inert gases. In such an example, the iodosilane precursor is diiodosilane or monoiodosilane. In such an example, the germanium precursor includes a germanium chloride compound selected from GeCl 4 , GeCl 2 , and GeCl 2 H 2 . In such an example, the boron precursor includes a boron chloride compound selected from BH 2 Cl, BCl 2 H, and BCl 3 .

[0011] To summarize the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described above. Of course, it should be understood that not all of these objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be implemented or carried out in a manner that achieves or optimizes one advantage or a group of advantages taught or suggested herein, without necessarily achieving other objects or advantages taught or suggested herein.

[0012] All such embodiments are within the scope of the invention disclosed herein. From the following detailed description of certain embodiments with reference to the accompanying drawings, these and other embodiments will become apparent to those skilled in the art, and the invention is not limited to any particular embodiment disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] To facilitate the identification of any particular element or action being discussed, the most significant digit in the reference numeral refers to the figure number in which that element was first introduced.

[0014] When considered in conjunction with the following illustrative drawings, a more complete understanding of the embodiments of the present disclosure can be obtained by reference to the detailed description and the claims.

[0015] Figure 1 An exemplary method for depositing a boron-doped silicon germanium layer according to one or more embodiments of the present disclosure is shown.

[0016] Figure 2 An exemplary method for selectively depositing a boron-doped silicon germanium layer according to one or more embodiments of the present disclosure is shown.

[0017] Figure 3 A structure including a substrate according to one or more embodiments of the present disclosure is shown.

[0018] Figure 4 A structure including source / drain regions according to one or more embodiments of the present disclosure is shown.

[0019] Figure 5 A structure including a boron-doped silicon germanium layer according to one or more embodiments of the present disclosure is shown.

[0020] Figure 6 A structure including a metal layer according to one or more embodiments of the present disclosure is shown.

[0021] It should be understood that the elements in the drawings are shown for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some elements in the figures may be exaggerated relative to other elements to facilitate understanding of the illustrated embodiments of the present disclosure. Detailed Description

[0022] The following description of exemplary embodiments of the methods and compositions provided is merely exemplary and for illustrative purposes only. The following description is not intended to limit the scope of the present disclosure or the claims. In addition, the recitation of multiple embodiments having the indicated features or steps is not intended to exclude other embodiments having additional features or steps, or other embodiments that combine different combinations of the recited features or steps.

[0023] As used herein, the term "substrate" can refer to any one or more underlying materials that can be used to form or on which devices, circuits, or films can be formed by a method according to embodiments of the present invention. The substrate can include bulk materials such as silicon (e.g., single-crystalline silicon), other Group IV materials such as germanium, or other semiconductor materials such as Group II-VI or III-V semiconductor materials, and can include one or more layers covering or underlying the bulk material. Additionally, the substrate can include various features such as depressions, protrusions, etc. formed within or on at least a portion of the substrate layer. For example, the substrate can include a bulk semiconductor material and a layer of insulating or dielectric material covering at least a portion of the bulk semiconductor material. Further, the term "substrate" can refer to any one or more underlying materials that can be used or on which devices, circuits, or films can be formed. The "substrate" can be continuous or discontinuous; rigid or flexible; solid or porous. The "substrate" can be in any form such as powder, plate, or workpiece. The plate-like substrate can include wafers of various shapes and sizes. The substrate can be made of materials such as silicon, silicon germanium, silicon oxide, gallium arsenide, gallium nitride, and silicon carbide. The continuous substrate can extend beyond the boundaries of the processing chamber where the deposition process occurs and can be moved through the processing chamber such that the process continues until the end of the substrate is reached. The continuous substrate can be provided by a continuous substrate feed system that allows for the fabrication and output of the continuous substrate in any suitable form. Non-limiting examples of continuous substrates can include sheets, non-woven membranes, rolls, foils, meshes, flexible materials, a bundle of continuous filaments or fibers (i.e., ceramic fibers or polymer fibers). The continuous substrate can also include a carrier or sheet on which a discontinuous substrate is mounted. For example, the substrate can include a semiconductor material. The semiconductor material can include or be used to form one or more of the source, drain, or channel regions of a device. The substrate can also include an interlayer dielectric (e.g., silicon oxide) and / or a high dielectric constant material layer covering the semiconductor material. In this context, a high dielectric constant material (or high-k dielectric material) is a material having a dielectric constant greater than that of silicon dioxide.

[0024] As used herein, the terms "film" and / or "layer" can be used interchangeably and can refer to any continuous or discontinuous structure and material, such as a material deposited by a method disclosed herein. For example, a layer can include two-dimensional materials, three-dimensional materials, nanoparticles, partial or complete molecular layers, or partial or complete atomic layers, or a layer of atomic and / or molecular clusters that can be composed, in part or in whole, of a plurality of dispersed atoms on the surface of the substrate and / or embedded within the substrate and / or embedded in a device fabricated on the substrate. A layer can include a material or layer having pinholes and / or islands. A layer can be at least partially continuous. A layer can be patterned, e.g., subdivided, and can be composed of a plurality of semiconductor devices.

[0025] As used herein, the term "gas" can include materials that are gaseous at normal temperature and pressure (NTP), evaporated solids, and / or evaporated liquids, and can consist of a single gas or a gas mixture, depending on the context. Gases other than those being processed, i.e., gases not introduced through gas distribution components, other gas distribution devices, etc., can be used, for example, to seal a reaction space and can include sealing gases. Precursors and reactants can be gases. Exemplary sealing gases include noble gases, nitrogen, etc. In some cases, the term "precursor" can refer to a compound that participates in a chemical reaction to produce another compound, particularly a compound that constitutes a film matrix or a film backbone. Additionally, the term "reactant" can be used interchangeably with the term "precursor".

[0026] As used herein, the term "epitaxial layer" can refer to a substantially single-crystalline layer directly on a underlying substantially single-crystalline substrate or layer.

[0027] As used herein, the term "chemical vapor deposition" can refer to any process in which a substrate is exposed to one or more volatile precursors (and optionally additional process gases) that react and / or decompose on the substrate surface to produce a desired deposition.

[0028] As used herein, the term "silicon germanium" can refer to a semiconductor material comprising silicon and germanium, and can be expressed as Si 1- x Ge x , where 1≥x≥0, or 0.8≥x≥0.1, or 0.6≥x≥0.2, or a material comprising silicon and germanium having the compositions described herein. Additionally, the term "silicon germanium" can be expressed as SiGe, and when the silicon germanium is doped with a boron dopant, it can be further expressed as SiGe:B. Similarly, a silicon material doped with a boron dopant can be expressed as Si:B.

[0029] As used herein, the term "fully strained" can refer to an epitaxial deposition layer of a first material that is lattice-matched to a crystalline substrate or crystalline layer of a second material below, where the first material is composed of a different material and / or different material composition from the second material. A "fully strained" epitaxial deposition layer has not undergone strain relaxation and thus has no or substantially no dislocations induced by strain relaxation.

[0030] Many example materials are given in the presently disclosed embodiments, and it should be noted that the chemical formulas given for each example material should not be construed as limiting, and the non-limiting example materials given should not be limited by the example stoichiometries given.

[0031] In the specification, it should be understood that the terms "on" or "above" can be used to describe relative positional relationships. Another element, film, or layer can be directly on the layer, or another layer (intermediate layer) or element can be interposed therebetween, or a layer can be disposed on the layer but not completely cover the surface of the layer. Thus, unless the term "directly" is used alone, the terms "on" or "above" will be interpreted as relative concepts. Similarly, it should be understood that the terms "under", "below", or "beneath" will be interpreted as relative concepts.

[0032] Various embodiments of the present disclosure relate to methods and compositions for depositing boron-doped silicon germanium layers (SiGe:B). As elaborated in more detail below, the methods and related compositions of the present disclosure employ a chemical vapor deposition process (e.g., an epitaxial deposition process) to deposit SiGe:B layers having a high active dopant concentration and a high germanium content. The epitaxial deposition process of the present disclosure can employ a composition (e.g., a deposition gas composition) including an iodide silane precursor as a silicon precursor (either as a single silicon precursor or in addition to other silicon precursors). The epitaxial deposition method of the present disclosure further includes a selective epitaxial deposition process, in which the deposited SiGe:B layer is preferentially deposited on a first surface (Surface A) relative to a second surface (Surface B). In such an example, the selective epitaxial deposition process can include a cyclic deposition process or a cyclic deposition-etch process.

[0033] As the device density in integrated circuits (e.g., logic devices and circuits) increases, the area between the source / drain regions of transistors and the metal interconnect layers (e.g., the middle section) continues to shrink. As the contact resistivity (ρ C ) becomes increasingly important, this reduction in the interconnect device area can limit device performance. Accordingly, embodiments of the present disclosure also provide methods for reducing the contact resistivity (ρ C ) by being able to deposit boron-doped silicon germanium layers having a high active dopant concentration and a high germanium content. In such embodiments, the contact resistivity (ρ C ) can be reduced by increasing the active doping concentration in the source / drain regions. Additionally, in such an example, the contact resistivity (ρ C ) can be reduced by decreasing the Schottky barrier height (SBH) between the source / drain regions and the metal of the interconnect layer.

[0034] More specifically, according to an example of the present disclosure, a thin contact layer including a boron-doped silicon germanium layer can be deposited on the source / drain regions of a transistor structure. In such an example, the thin contact layer includes the SiGe:B layer of the present disclosure (i.e., having a high germanium and active dopant concentration). Additionally, in such an example, the contact layer can be kept thin (e.g., less than X nm), and this can better control the lattice mismatch between the contact layer and the underlying layer, thus maintaining the strain on the contact layer without forming (or reducing the formation of) defects such as misfit dislocations. Further, the high active dopant concentration in the SiGe:B layer of the present disclosure can help compensate for the strain caused by the high germanium content in the SiGe:B layer.

[0035] Conventional deposition methods cannot successfully achieve the high active donor concentration and germanium content achievable by the present invention. For example, as the germanium content in the SiGe:B layer increases, conventional methods for depositing the SiGe:B layer often result in a plateau and ultimately a reduction in the active dopant concentration.

[0036] Thus, according to an example of the present disclosure, there is provided a method for depositing a boron-doped silicon germanium layer having a high active dopant concentration and a high germanium content by employing a composition (e.g., a deposition gas composition or a deposition gas formulation) including an iodide silane precursor. In such an example, the methods and compositions disclosed herein can increase the active doping concentration in the deposited boron-doped silicon germanium layer to 3×10 21 cm -3 or more, while maintaining the germanium concentration in the SiGe:B layer above 50%.

[0037] Now turning to the drawings, Figure 1 illustrates an exemplary method 100 for depositing a boron-doped silicon germanium layer having a high active dopant concentration and a high germanium content according to an embodiment of the present disclosure. Briefly, method 100 includes the following steps: placing a substrate in a reaction chamber (step 102), heating the substrate to a deposition temperature (step 104), depositing a boron-doped silicon germanium layer on the substrate surface (step 106) by introducing a germanium precursor into the reaction chamber (step 108), introducing a boron precursor into the reaction chamber (step 110), and introducing a silicon precursor including an iodide silane precursor into the reaction chamber (112).

[0038] More specifically, according to an example of the present disclosure, method 100 includes step 102, which includes placing a substrate in a reaction chamber. In such an example, the reaction chamber can include the reaction chamber of a chemical vapor deposition system. However, it is also conceivable that other reaction chambers (such as atomic layer deposition reaction chambers) and alternative chemical vapor deposition systems can also be used to implement the embodiments of the present disclosure. In some embodiments, the reaction chamber is configured to perform an epitaxial deposition process. In some embodiments, the reaction chamber can form part of a cluster-type semiconductor processing system, which can include a plurality of processing modules for performing various semiconductor processing operations. In such an embodiment, the cluster-type semiconductor processing system can include two or more reaction chambers configured to perform the epitaxial deposition process of the present disclosure.

[0039] According to an example of the present disclosure, method 100 includes step 104, which includes heating the substrate to a deposition temperature. In some embodiments of the present disclosure, the deposition temperature (such as the substrate temperature during deposition) is less than 500 °C, less than 450 °C, less than 400 °C, less than 350 °C, less than 300 °C, less than 250 °C or less than 200 °C. In some embodiments of the present disclosure, the deposition temperature is between 200 °C and 500 °C, between 200 °C and 450 °C, between 250 °C and 400 °C or between 250 °C and 350 °C.

[0040] In addition to controlling the temperature of the substrate, the pressure in the reaction chamber can also be adjusted. For example, in some embodiments of the present disclosure, the pressure in the reaction chamber during deposition is less than 760 Torr, less than 350 Torr, less than 100 Torr, less than 50 Torr, less than 25 Torr, less than 10 Torr or less than 5 Torr. In some embodiments, the pressure in the chamber body during deposition is between 5 Torr and 760 Torr, or between 10 Torr and 200 Torr, or between 20 Torr and 100 Torr.

[0041] According to an example of the present disclosure, method 100 includes step 106, which includes depositing a boron-doped silicon germanium layer on the substrate surface. In some embodiments of the present disclosure, the deposition process (step 106) is a thermal deposition process performed in the reaction chamber without using excited species generated from a plasma, that is, the deposition process is a thermal deposition process performed in a plasma-free environment. In some embodiments, the deposition process is a chemical vapor deposition (CVD) process. In such an embodiment, the chemical vapor deposition process can be an epitaxial deposition process.

[0042] According to an example of the present disclosure, depositing a boron-doped silicon germanium layer (step 106) includes the following steps: introducing a germanium precursor into the reaction chamber (step 108), introducing a boron precursor into the reaction chamber (step 110), and introducing a silicon precursor including an iodide silane precursor into the reaction chamber (step 112). In some embodiments, steps 108, 110, and 112 are performed in parallel, or at least partially in parallel. In other words, in some embodiments, the germanium precursor, the boron precursor, and the iodide silane precursor are introduced into the reaction chamber together or at least with some overlap in the injection times of the germanium precursor, the boron precursor, and the iodide silane precursor (i.e., time overlap). In other embodiments of the present disclosure, steps 108, 110, and 112 may be performed sequentially, without any substantial overlap between each process step. In such embodiments, steps 108, 110, and 112 may be performed in any order and may include repeating one or more of steps 108, 110, and 112. In other embodiments, steps 108, 110, and 112 may be performed as part of a repeated deposition cycle (i.e., a cyclic deposition process), and in such examples, one or more additional steps may be added to the deposition cycle (as described in more detail below).

[0043] According to an example of the present disclosure, step 108 includes introducing a germanium precursor into the reaction chamber. In such an example, the germanium precursor may include germane, such as germane (GeH 4 ), digermane (Ge 2 H 6 ), trigermane (Ge 3 H 8 ), or germylsilane (GeH 6 Si). According to an example of the present disclosure, the germanium precursor may include a germanium halide compound. In such an example, the germanium precursor includes a germanium chloride compound. Further, in such an example, the germanium chloride compound is selected from GeCl 4 , GeCl 2 , and GeCl 2 H 2 . In some embodiments, during step 108, two or more germanium precursors are introduced into the reaction chamber. In such embodiments, the two or more germanium precursors may include germane, a germanium chloride compound, or a mixture of germane and a germanium chloride compound.

[0044] According to a further example of the present disclosure, step 110 includes introducing a boron precursor into the reaction chamber. In such an example, the boron precursor may include borane, such as diborane (B 2 H 6 ) or deuterium-diborane (B 2 D 6) According to an example of the present disclosure, the boron precursor may include a boron halide compound. In such an example, the boron precursor includes a boron chloride compound. Further, in such an example, the boron chloride compound is selected from BH 2 Cl, BCl 2 H, and BCl 3 . In some embodiments, during step 110, two or more boron precursors are introduced into the reaction chamber. In such embodiments, the two or more boron precursors may include borane, a boron chloride compound, or a mixture of borane and a boron chloride compound.

[0045] According to a further example of the present disclosure, step 112 includes introducing a silicon precursor into the reaction chamber. In some embodiments, step 112 includes introducing a silicon precursor comprising an iodide silane precursor into the reaction chamber. In some embodiments, step 112 includes introducing a silicon precursor comprising an iodide silane precursor and an additional silicon precursor into the reaction chamber. In some embodiments, step 112 includes introducing a single silicon precursor consisting of an iodide silane precursor into the reaction chamber. In some embodiments, step 112 includes introducing a silicon precursor comprising two or more iodide silane precursors into the reaction chamber.

[0046] According to an example of the present disclosure, the silicon precursor may include a compound having a chemical formula including silicon (Si), hydrogen (H), and a halide. In such an example, the silicon precursor may include a compound having a chemical formula including silicon (Si), hydrogen (H), and iodine (I). In such an example, the silicon precursor may include an iodide silane precursor. In such an example, the iodide silane precursor is selected from monoiodosilane, diiodosilane, triiodosilane, and tetraiodosilane. In some embodiments, the silicon precursor consists of monoiodosilane. In some embodiments, the silicon precursor consists of diiodosilane. In some embodiments, the silicon precursor consists of triiodosilane. In some embodiments, the silicon precursor consists of tetraiodosilane.

[0047] According to an example of the present disclosure, the silicon precursor may include monoiodosilane. In such an example, the monoiodosilane silicon precursor may have a higher vapor pressure than the diiodosilane silicon precursor (at a specific deposition temperature), which may result in a higher concentration of the silicon precursor delivered to the reaction chamber. In such an example, the monoiodosilane silicon precursor may form an intermediate reaction product SiHI instead of SiI 2 intermediate, which may promote a higher growth rate of the boron-doped silicon germanium layer on the substrate, such as a substrate including a silicon surface. Thus, in some embodiments, the silicon precursor consists of monoiodosilane.

[0048] According to examples of the present disclosure, the silicon precursor may include higher-order iodosilane precursors. Without being bound by any theory or process, the higher-order iodosilane precursors may include weaker Si-Si bonds, which may provide benefits in the deposition of the boron-doped silicon-germanium layer of the present disclosure. In such examples, the silicon precursor may include higher-order iodosilane precursors such as, but not limited to, disilane, trisilane, and tetrasilane. In some embodiments, the silicon precursor includes an iodosilane precursor having the general formula SiH n I (4-n) .

[0049] As described above, the silicon precursor may include two or more silicon precursors. In such examples, the silicon precursor may include an iodosilane precursor and one or more additional silicon precursors. In some embodiments, the silicon precursor may include an iodosilane precursor and one additional silicon precursor. In some embodiments, the additional silicon precursor may include a silicon hydride precursor. In such embodiments, the silicon hydride precursor is selected from silane (SiH 4 ), disilane (Si 2 H 6 ), trisilane (Si 3 H 8 ), and tetrasilane (Si 4 H 10 ). In some embodiments, the additional silicon precursor may include a silicon halide precursor. According to examples of the present disclosure, the silicon halide precursor may include a silicon chloride precursor. In such examples, the silicon chloride precursor is selected from monochlorosilane (MCS), dichlorosilane (DCS), trichlorosilane (TCS), hexachlorodisilane (HCDS), octachlorotrisilane (OCTS), and silicon tetrachloride (STC). Some of the benefits of adding the silicon halide precursor to the silicon precursor will be described in more detail below.

[0050] According to examples of the present invention, the boron-doped silicon-germanium layer is deposited at a growth rate of greater than 0.5 nm / min, greater than 1 nm / min, greater than 1.5 nm / min, greater than 2 nm / min, greater than 2.5 nm / min, greater than 3 nm / min, greater than 4 nm / min, greater than 5 nm / min, greater than 6 nm / min, greater than 8 nm / min, or greater than 10 nm / min or between 1 nm / min and 10 nm / min.

[0051] Various embodiments of the present disclosure also include a method of selectively depositing a boron-doped silicon-germanium layer by employing a selective deposition process. According to examples of the present disclosure, the selective deposition process includes a selective chemical vapor deposition process. In some embodiments, the selective deposition process includes a selective epitaxial deposition process. In such examples, the selective epitaxial deposition process selectively (i.e., preferentially) deposits the boron-doped silicon-germanium layer on a first surface (surface A) relative to a second surface (surface B).

[0052] Those skilled in the art will understand that selective deposition can be either fully selective or partially selective. A partially selective process can produce a fully selective layer through post-deposition etching that removes all deposited material from surface B but not all deposited material from surface A. Since the etch-back process can leave a fully selective structure without the need for an expensive masking process, selective deposition does not need to be fully selective to obtain the desired benefits.

[0053] According to an example of the present disclosure, the selective deposition process of the present disclosure is capable of selectively depositing a boron-doped silicon germanium layer on a dielectric surface (surface A) relative to a semiconductor surface (surface B). In such an example, the dielectric surface (surface A) can include, but is not limited to, a silicon oxide surface (e.g., SiO 2 ) and / or a silicon nitride surface (e.g., Si 3 N 4 ). Additionally, in such an example, the semiconductor surface (surface B) can include, but is not limited to, a silicon surface (e.g., Si).

[0054] According to another example of the present disclosure, the selective deposition process of the present disclosure is capable of selectively depositing a boron-doped silicon germanium layer on a first dielectric surface (surface A) relative to a second dielectric surface (surface B). In such an example, the first dielectric surface (surface A) includes a silicon nitride surface and the second dielectric surface (surface B) includes a silicon oxide surface.

[0055] The selectivity of the deposition process on surface A relative to surface B can be given by the percentage calculated as [(deposition on surface A) - (deposition on surface B)] / (deposition on surface A). The deposition can be measured by any of a variety of methods. For example, the deposition can be given as a measured thickness of the deposited material or can be given as a measured amount of the deposited material. In some embodiments, the selectivity of the selective deposition of the boron-doped silicon germanium layer on surface A relative to surface B is greater than 10%, greater than 50%, greater than 75%, greater than 85%, greater than 90%, greater than 93%, greater than 95%, greater than 98%, greater than 99%, greater than 99.5%, equal to approximately 100%.

[0056] Figure 2Illustrated is an exemplary method 200 for selectively depositing a boron-doped silicon germanium layer having a high active dopant concentration and a high germanium content in accordance with embodiments of the present disclosure. In brief, method 200 includes the steps of positioning a substrate in a reaction chamber (step 102), heating the substrate to a deposition temperature (step 104), and selectively depositing a boron-doped silicon germanium layer (step 206). In some embodiments, the selective deposition process of method 200 includes introducing a germanium precursor into the reaction chamber (step 108), introducing a boron precursor into the reaction chamber (step 110), and introducing a silicon precursor including an iodosilane precursor into the reaction chamber (112), as previously described. In some embodiments, the selective deposition process of method 200 optionally includes the steps of introducing an etchant into the reaction chamber during deposition step 206 (e.g., by performing optional step 208) and / or after deposition step 206 is completed (e.g., by performing optional etch step 214). In some embodiments, the selective deposition process of method 200 optionally includes the step of introducing a silicon chloride precursor into the reaction chamber (step 210). As with method 100, steps 108, 110, 112, 208, 210, and 214 of method 200 may be performed in any order or sequence in parallel (or at least partially in parallel) and may include multiple repetitions of one or more steps. According to additional examples of the present disclosure, the selective deposition process of method 200 may optionally include a cyclic deposition process and / or a cyclic deposition-etch process, as shown by deposition loop 212, as described in more detail below.

[0057] According to examples of the present disclosure, selectively depositing a boron-doped silicon germanium layer having a high active dopant concentration and a high germanium content may include introducing a chlorine precursor / reactant / etchant to increase the selectivity of the deposition process while still employing a silicon precursor including an iodosilane precursor. Thus, the selective deposition process of the present disclosure may include introducing a silicon chloride precursor together with (either together or separately) the iodosilane precursor into the reaction chamber to increase the deposition selectivity of the boron-doped silicon germanium layer. In such examples, the silicon chloride precursor includes one or more of the aforementioned silicon chloride precursors. In some embodiments, the silicon chloride precursor includes dichlorosilane (DCS). Additionally, the selective deposition process of the present disclosure may employ a germanium chloride compound as at least one germanium precursor and a boron chloride compound as at least one boron precursor to further increase the deposition selectivity of the boron-doped silicon germanium layer. In such examples, the germanium chloride compound is selected from GeCl 4 、GeCl 2 and GeCl 2 H 2 ,chlorine boron precursor is selected from BH 2 Cl、BCl 2 H. In such examples, in addition to or instead of a non-halide germanium precursor (e.g., GeH 4 、Ge 2 H6 , Ge 3 H 8 , GeH 6 In addition to (or instead of) non-halide boron precursors (such as B 2 H 6 , B 2 D 6 ), germanium chloride compounds can be used. Additionally, in such examples, in addition to or instead of non-halide boron precursors (e.g., B 2 ), boron chloride compounds can be used. Further, the selective deposition process of the present disclosure can include introducing an etchant into the reaction chamber during or after deposition (e.g., by an etch-back process) to further improve the deposition selectivity of the boron-doped silicon-germanium layer. In some embodiments, the etchant includes a halide etchant. For example, in some embodiments, the halide etchant includes chlorine (Cl

[0058] The following detailed description of the selective deposition process of the present disclosure does not repeat or only briefly describes the steps of method 200 that have been described in detail above with respect to method 100, such as steps 102, 104, 108, 110, and 112. Additionally, the following selective deposition process can also include introducing a chloride precursor / reactant / etchant to increase the selectivity of the deposition process as described above.

[0059] In some embodiments of the present disclosure, method 200 includes a non-cyclic deposition process for selectively depositing a boron-doped silicon-germanium layer. In such a non-cyclic example, the deposition cycle loop 212 is omitted. In such an example, deposition step 206 includes introducing a germanium precursor into the reaction chamber, introducing a boron precursor into the reaction chamber, and introducing a silicon precursor including an iodide silane precursor into the reaction chamber, as described above. In such a non-cyclic example of the present disclosure, deposition step 206 optionally includes introducing a silicon chloride precursor into the reaction chamber (step 208). In such a non-cyclic example of the present disclosure, deposition step 206 can also optionally include introducing an etchant into the reaction chamber during deposition step 206 (e.g., by performing optional etch step 208) and / or after deposition step 206 is completed (e.g., by performing optional etch step 214). In some embodiments, the etchant is introduced after depositing the boron-doped silicon-germanium layer (e.g., by performing step 214 after step 206 is completed) to etch back any unwanted boron-doped silicon-germanium layer, thereby improving the selectivity of the deposition process.

[0060] In some embodiments of the present disclosure, method 200 includes a selective cyclic deposition process for depositing a boron-doped silicon germanium layer. In such an example, the selective deposition method 200 may include a cyclic deposition process or a cyclic deposition-etch process. In such an example, deposition step 206 includes one or more repeated deposition cycles 216 (including deposition cycle loop 212), wherein a unit deposition cycle 216 includes introducing a germanium precursor into the reaction chamber, introducing a boron precursor into the reaction chamber, introducing a silicon precursor comprising an iodide silane precursor into the reaction chamber, optionally introducing a silicon chloride precursor into the reaction chamber (step 210), and optionally introducing an etchant into the reaction chamber (step 210). Each step of deposition cycle 216 may start and / or terminate in any order. Additionally, prior to proceeding to subsequent steps of deposition cycle 216, deposition cycle 216 may include one or more repetitions (e.g., 1-10 or 1-5 repetitions) of each step. In some embodiments, depending on the desired layer properties of the boron-doped silicon germanium layer, a deposition cycle may differ from subsequent deposition cycles. In some embodiments, a deposition cycle may include one or both of optional steps 208 and 210, while subsequent deposition cycles may omit one or both of optional steps 208 and 210. In some embodiments, a deposition cycle may include one or more of steps 108, 110, and 112, while subsequent deposition cycles may omit one or more of steps 108, 110, and 112. In some embodiments, one or more steps of deposition cycle 216 may be performed in parallel, or at least partially in parallel. According to an example of the present disclosure, deposition cycle 216 may be repeated as needed as indicated by deposition cycle loop 212. For example, in some embodiments, deposition cycle 216 may be repeated more than 2, 4, 6, 10, 20, 30, 40, 50, 75, or 100 times. Termination of the execution of repeated deposition cycle 216 may be based on having performed a predetermined number of repetitions or reaching the desired thickness of the boron-doped silicon germanium layer.

[0061] According to an example of the present disclosure, the selective deposition process of the present disclosure is capable of selectively depositing a boron-doped silicon germanium layer on a dielectric surface (surface A) relative to a semiconductor surface (surface B). In such an example, the dielectric surface (surface A) may include a silicon nitride surface and / or a silicon oxide surface, and the semiconductor surface (surface B) may include a silicon surface. In such an example, the boron-doped silicon germanium layer is selectively deposited on surface A relative to surface B with a selectivity greater than 10%, greater than 50%, greater than 75%, greater than 85%, greater than 90%, greater than 93%, greater than 95%, greater than 98%, greater than 99%, greater than 99.5%, equal to approximately 100%.

[0062] According to a further example of the present disclosure, the selective deposition process of the present disclosure is capable of selectively depositing a boron-doped silicon germanium layer on a first dielectric surface (Surface A) relative to a second dielectric surface (Surface B). In such an example, the first dielectric surface (Surface A) comprises a silicon nitride surface, and the second dielectric surface (Surface B) may comprise a silicon oxide surface. In such an example, the boron-doped silicon germanium layer is selectively deposited on Surface A relative to Surface B, with a selectivity greater than 10%, greater than 50%, greater than 75%, greater than 85%, greater than 90%, greater than 93%, greater than 95%, greater than 98%, greater than 99%, greater than 99.5%, equal to approximately 100%.

[0063] Various embodiments of the present disclosure also relate to boron-doped silicon germanium layers deposited by the above methods.

[0064] According to an example of the present disclosure, Figure 3 Structure 300 is shown, which includes a substrate 302 including a surface 304. In some embodiments, the boron-doped silicon germanium layer of the present disclosure is directly deposited on the surface 304 of the substrate 302. As a non-limiting example, the surface 304 may include, for example, one or more of silicon, silicon germanium, silicon oxide, or silicon nitride.

[0065] According to a further example of the present disclosure, Figure 4 Structure 400 is shown, which includes a substrate 302 of a device structure and source / drain regions 402. In such an example, the source / drain regions 402 may include silicon germanium source / drain regions, which include one or more layers of silicon germanium with various compositions, thicknesses, and doping concentrations. In such an example, the source / drain regions 402 include a surface 404. Additionally, in such an example, the surface 404 includes a silicon germanium surface. In other examples, the surface 404 includes one or more of a silicon surface, silicon oxide, silicon nitride surface, and silicon germanium surface.

[0066] According to a further example of the present disclosure, Figure 5 Structure 500 is shown, which includes the aforementioned substrate 302 and source / drain regions 402. In such an example, structure 500 includes a boron-doped silicon germanium layer 502 deposited by the method of the present disclosure. In some embodiments, the boron-doped silicon germanium layer 502 is directly epitaxially deposited on the surface 404 of the source / drain regions 402. In some embodiments, the boron-doped silicon germanium layer 502 has a different composition and / or lattice constant from the underlying source / drain regions 402. In some embodiments, the boron-doped silicon germanium layer 502 has a first germanium concentration, and the source / drain regions 402 include a silicon germanium layer having a second germanium concentration different from the first germanium concentration. In some embodiments, the boron-doped silicon germanium layer 502 is lattice-matched to the underlying source / drain regions 402. In some embodiments, the boron-doped silicon germanium layer 502 is fully strained to the underlying source / drain regions 402 and has substantially no misfit dislocations.

[0067] According to an example of the present disclosure, the boron-doped silicon germanium layer 502 has an average layer thickness of less than 20 nm, less than 15 nm, less than 10 nm, less than 7 nm, or less than 5 nm. In some embodiments, the boron-doped silicon germanium layer 502 has an average layer thickness between 5 nm and 20 nm.

[0068] According to an example of the present disclosure, the boron-doped silicon germanium layer 502 has a high boron dopant concentration and a resulting high active dopant concentration. In such an example, the boron-doped silicon germanium layer 502 has greater than 2.0×10 21 cm -3 、 greater than 2.5×10 21 cm -3 、 greater than 3.0×10 21 cm -3 、 greater than 3.5×10 21 cm -3 、 greater than 4.0×10 21 cm -3 、 greater than 4.5×10 21 cm -3 、 or greater than 5.0×10 21 cm -3 active dopant concentration. In such an example, the boron-doped silicon germanium layer 502 also has a high germanium content. For example, the boron-doped silicon germanium layer 502 has a germanium concentration (atomic %) greater than 50%, greater than 55%, greater than 60%, greater than 65%, greater than 70%, greater than 75%, greater than 80%, greater than 85%, or greater than 90%.

[0069] According to a further example of the present disclosure, Figure 6 FIG. 600 is shown, which includes the aforementioned substrate 302, source / drain regions 402, and boron-doped silicon germanium layer 502. Structure 600 further includes a metal layer 602 formed on (or directly formed on) the boron-doped silicon germanium layer 502. In such an example, the boron-doped silicon germanium layer 502 includes a contact layer, and the metal layer 602 may include an electrode for providing electrical contact to the boron-doped silicon germanium layer 502 (and underlying layers). In some embodiments, structure 600 includes a part of a transistor device structure, such as a surround gate device structure, a nanosheet device structure, a finfet device structure, and a complementary FET (CFET) device structure.

[0070] Various embodiments of the present disclosure also relate to compositions (e.g., deposition gas compositions or deposition gas formulations) for depositing the boron-doped silicon germanium layer of the present disclosure.

[0071] According to an example of the present disclosure, embodiments of the present disclosure include for epitaxial deposition having greater than 3×10 21 cm -3A composition of a boron-doped silicon-germanium layer having an active dopant concentration and a germanium content greater than 50 atomic %. In such an example, the composition comprises an iodosilane precursor having less than 1% metal impurities and less than 1% phosphorus impurities. In some embodiments, the composition comprises an iodosilane precursor having less than 1.5% metal impurities, less than 1% metal impurities, less than 0.8% metal impurities, less than 0.5% metal impurities, or less than 0.3% metal impurities. In some embodiments, the composition comprises an iodosilane precursor having less than 1.5% phosphorus impurities, less than 1% phosphorus impurities, less than 0.8% phosphorus impurities, less than 0.5% phosphorus impurities, or less than 0.3% phosphorus impurities. In some embodiments, the composition comprises an iodosilane precursor having less than 1.5% carbon impurities, less than 1% carbon impurities, less than 0.8% carbon impurities, less than 0.5% carbon impurities, or less than 0.3% carbon impurities. In some embodiments, the composition comprises an iodosilane precursor having less than 1.5% carbon impurities, less than 1% oxygen impurities, less than 0.8% oxygen impurities, less than 0.5% oxygen impurities, or less than 0.3% oxygen impurities.

[0072] In some embodiments, the composition consists essentially of an iodosilane precursor, a germanium precursor, a boron precursor, and one or more additional inert gases. In such embodiments, the composition has less than 1.5% metal impurities, less than 1% metal impurities, less than 0.8% metal impurities, less than 0.5% metal impurities, or less than 0.3% metal impurities. Further, in such embodiments, the composition has less than 1.5% phosphorus impurities, less than 1% phosphorus impurities, less than 0.8% phosphorus impurities, less than 0.5% phosphorus impurities, or less than 0.3% phosphorus impurities. Further, in such embodiments, the composition has less than 1.5% carbon impurities, less than 1% carbon impurities, less than 0.8% carbon impurities, less than 0.5% carbon impurities, or less than 0.3% carbon impurities. Further, in such embodiments, the composition has less than 1.5% oxygen impurities, less than 1% oxygen impurities, less than 0.8% oxygen impurities, less than 0.5% oxygen impurities, or less than 0.3% oxygen impurities.

[0073] In some embodiments, the iodosilane precursor is diiodosilane. In some embodiments, the iodosilane precursor is monoiodosilane. In some embodiments, the composition includes an additional silicon precursor. In some embodiments, the composition includes a germanium precursor, which includes a germanium chloride compound selected from GeCl 4 、GeCl 2 and GeCl 2 H 2 . In some embodiments, the composition includes a boron precursor, which includes a compound selected from BH 2 Cl、BCl 2 H and BCl 3A boron chloride compound. In some embodiments, one or more additional inert gases include at least one of nitrogen, argon, and helium.

[0074] According to a further example of the present disclosure, the composition is capable of depositing a boron-doped silicon germanium layer at a rate greater than 0.5 nm / min, greater than 1 nm / min, greater than 1.5 nm / min, greater than 2 nm / min, greater than 2.5 nm / min, greater than 3 nm / min, greater than 4 nm / min, greater than 5 nm / min, greater than 6 nm / min, greater than 8 nm / min, or greater than 10 nm / min, or between 1 nm / min and 10 nm / min. It should be noted that the growth rate depends on many factors, including but not limited to composition, deposition temperature, reaction chamber pressure, and germanium composition. In some embodiments, the composition includes a silicon precursor consisting of disilane iodide, and the boron-doped silicon germanium layer 502 is deposited at a rate greater than 0.5 nm / min, greater than 1 nm / min, greater than 1.5 nm / min, greater than 2 nm / min, greater than 2.5 nm / min, greater than 3 nm / min, greater than 4 nm / min, greater than 5 nm / min, greater than 6 nm / min, greater than 8 nm / min, or greater than 10 nm / min, or between 1 nm / min and 10 nm / min. In some embodiments, the composition includes a silicon precursor consisting of monosilane iodide, and the boron-doped silicon germanium layer 502 is deposited at a rate greater than 0.5 nm / min, greater than 1 nm / min, greater than 1.5 nm / min, greater than 2 nm / min, greater than 2.5 nm / min, greater than 3 nm / min, greater than 4 nm / min, greater than 5 nm / min, greater than 6 nm / min, greater than 8 nm / min, or greater than 10 nm / min, or between 1 nm / min and 10 nm / min. In such an example, the composition enables the boron-doped silicon germanium layer to be deposited at a deposition temperature between 250 °C and 400 °C. In such an example, the composition enables the boron-doped silicon germanium layer to be deposited as a fully strained layer, i.e., without strain relaxation and any associated misfit-type dislocations. In such an example, the composition is capable of depositing a boron-doped silicon germanium layer without significantly depositing a parasitic boron-doped silicon germanium layer on the surface of the reaction chamber. In such an example, the composition enables the boron-doped silicon germanium layer to be deposited with a germanium composition greater than 50 atomic %, and an active donor concentration greater than 3×10 21 cm -3 .

[0075] Although certain embodiments and examples have been discussed, those skilled in the art will understand that the scope of the claims extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses and their obvious modifications and equivalents. Indeed, various modifications of the present disclosure, such as alternative useful combinations of the described elements, will become apparent to those skilled in the art from the description, in addition to those shown and described herein. Such modifications and embodiments are also intended to fall within the scope of the appended claims.

[0076] In the present disclosure, in the absence of specified conditions and / or structures, those skilled in the art can readily provide such conditions and / or structures as routine experimentation in view of the present disclosure.

Claims

1. A method for thermally depositing a boron-doped silicon germanium layer having a high active dopant concentration and a high germanium content, the method comprising: placing a substrate in a reaction chamber; heating the substrate to a deposition temperature; as well as Depositing a boron-doped silicon germanium layer on a substrate surface by an epitaxial deposition process includes: introducing a germanium precursor into a reaction chamber; introducing a boron precursor into the reaction chamber; and A silicon precursor including an iodosilane precursor is introduced into the reaction chamber.

2. The method according to claim 1, wherein: The deposition temperature is between 250°C and 400°C.

3. The method according to claim 1, wherein: The germanium precursor includes a germanium chloride compound selected from the group consisting of GeCl4, GeCl2 and GeCl2H2.

4. The method according to claim 1, wherein: The boron precursor includes a boron chloride compound selected from the group consisting of BH2Cl, BCl2H and BCl3.

5. The method according to claim 1, wherein: The iodosilane precursor is selected from monoiodosilane, diiodosilane, triiodosilane and tetraiodosilane.

6. The method according to claim 1, wherein: The iodosilane precursor consists of diiodosilane.

7. The method according to claim 1, wherein: The iodosilane precursor consists of monoiodosilane.

8. The method according to claim 1, wherein: The substrate includes a silicon germanium source / drain region, and the boron-doped silicon germanium layer is epitaxially deposited directly on the silicon germanium source / drain region.

9. The method according to claim 1, wherein: The boron-doped silicon germanium layer has a thickness greater than 3×10 21 cm -3 active dopant concentration and a germanium content greater than 50 atomic %.

10. The method according to claim 1, wherein: The epitaxial deposition process is a selective deposition process, which selectively deposits the boron-doped silicon germanium layer on surface A relative to surface B, wherein surface A is a silicon nitride surface and surface B is a silicon oxide surface, or wherein surface A is a silicon oxide surface or a silicon nitride surface and surface B is a silicon surface. The method of claim 10 , further comprising introducing an etchant into the reaction chamber.

12. The method according to claim 11, wherein: The selective deposition process also includes a cyclic deposition process or a cyclic deposition-etching process.

13. The method according to claim 2, wherein: The boron-doped silicon germanium layer is deposited at a growth rate between 1 nm / min and 10 nm / min with an average layer thickness between 5 nm and 20 nm.

14. A method of forming a contact layer to a silicon germanium source / drain region, the method comprising: placing a substrate in a reaction chamber, the substrate comprising one or more silicon germanium source / drain regions; heating the substrate to a deposition temperature between 250°C and 400°C; as well as Depositing a boron-doped silicon germanium layer on the silicon germanium source / drain region by an epitaxial deposition process by introducing a single silicon precursor including an iodosilane precursor, a germanium precursor, and a boron precursor into a reaction chamber; Among them, the boron-doped silicon germanium layer has a value greater than 3×10 21 cm -3 active dopant concentration and a germanium content greater than 50 atomic %.

15. The method according to claim 14, wherein: At least one of the germanium precursor and the boron precursor includes a chloride compound.

16. The method according to claim 14, wherein: The epitaxial deposition process is a selective deposition process, which selectively deposits the boron-doped silicon germanium layer on surface A relative to surface B, wherein surface A is a silicon nitride surface and surface B is a silicon oxide surface, or wherein surface A is a silicon oxide surface or a silicon nitride surface and surface B is a silicon surface.

17. The method of claim 16, further comprising introducing an etchant into the reaction chamber.

18. The method according to claim 1, wherein: The iodosilane precursor consists of diiodosilane or monoiodosilane.

19. A method for epitaxial deposition having a 21 cm -3 A composition for a boron-doped silicon germanium layer having an active dopant concentration of 1.50 Å and a germanium content greater than 50 atomic %, the composition comprising an iodosilane precursor having less than 1% of metal impurities and less than 1% of phosphorus impurities.

20. The composition according to claim 19, wherein The composition consists essentially of an iodosilane precursor, a germanium precursor, a boron precursor, and one or more additional inert gases.

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