A method of delta-doping a semiconductor surface

Abstract

The present application relates to the technical field of semiconductor surface delta doping, and particularly relates to a method for performing delta doping on a semiconductor surface. The present application provides a method for performing delta doping on a semiconductor substrate surface, comprising the following steps: after modifying the surface of a semiconductor substrate with a functional group, bonding a doping source through a surface chemical reaction, generating an S-O-D structure on the surface of the semiconductor substrate, removing oxygen atoms in the S-O-D structure, and obtaining a delta-doped semiconductor substrate; S in the S-O-D structure is an atom of the semiconductor substrate, O is an oxygen atom, and D is a doping atom. The method has mild conditions, is conducive to realizing large-scale production, and can realize doping of various metals or non-metals.

Description

Technical Field

[0001] This invention relates to the field of semiconductor surface delta doping technology, and more particularly to a method for delta doping on a semiconductor surface. Background Technology

[0002] Delta doping of semiconductor surfaces is an ultra-precise doping technique that confines impurity atoms within 1 to 2 atomic layers on the substrate surface. Its ideal doping distribution approximates a mathematical delta function, resulting in an extremely steep concentration gradient and negligible longitudinal diffusion. These characteristics enable the formation of near-ideal electrical junctions, which is crucial for realizing high-performance nanoelectronic devices (such as ultra-shallow junction transistors), high-frequency devices, and semiconductor quantum devices.

[0003] In delta-doping processes based on low-energy ion implantation and plasma immersion ion implantation, an inherent challenge is the inability to avoid lattice damage caused by ion bombardment. Furthermore, precise control of sub-10 nm doping depth and uniform impurity distribution remain challenging.

[0004] Delta doping based on molecular beam epitaxy can achieve extremely steep doping profiles and excellent crystal quality. However, this technique also has inherent limitations: low doping efficiency, high production costs, and difficulty in compatibility with silicon-based CMOS processes.

[0005] In delta doping using atomic layer deposition (ALD), the impurity source is first adsorbed onto a single layer through a surface self-confining reaction. Then, a capping layer is formed through low-temperature epitaxial growth, confining the dopant within the atomic-level interface. Finally, annealing methods such as laser annealing or rapid annealing are used to integrate the impurity atoms into the substrate lattice for activation. Therefore, the control of the doping depth is limited by the subsequent annealing process. Furthermore, this technique lacks commonly used impurity sources in semiconductor manufacturing, such as phosphorus, arsenic, and antimony sources.

[0006] Delta doping based on scanning probe microscopy (STM) requires hydrogen passivation of the semiconductor surface. Hydrogen atoms are removed using an STM tip, inducing surface monolayer adsorption of impurity sources (such as phosphine or arsine). The impurity atoms then directly attach to the substrate surface, forming a delta doping (SD) structure. Subsequently, low-temperature annealing causes the impurity atoms to lose hydrogen atoms while simultaneously integrating into the substrate lattice and becoming activated. The advantage of this technique lies in its atomic-level doping precision control. However, it also faces significant limitations, such as stringent requirements for impurity source selection, making large-scale implementation difficult. Summary of the Invention

[0007] In view of this, the object of the present invention is to provide a method for δ-doping on a semiconductor surface, wherein the method is under mild conditions, which is conducive to large-scale production and can achieve doping of various metals or non-metals.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for performing delta doping on the surface of a semiconductor substrate, comprising the following steps: After modifying the surface of a semiconductor substrate with functional groups, a dopant source is bonded to the surface through a surface chemical reaction to generate an SOD structure on the surface of the semiconductor substrate. Then, the oxygen atoms in the SOD structure are removed to obtain a δ-doped semiconductor substrate. In the SOD structure, S represents the atoms of the semiconductor substrate, O represents oxygen atoms, and D represents dopant atoms.

[0009] Preferably, the semiconductor substrate includes a group IV semiconductor substrate, a group III-V semiconductor substrate, or a group II-VI semiconductor substrate; the group IV semiconductor substrate includes a silicon substrate, a germanium substrate, a silicon-germanium alloy substrate, or a germanium-tin alloy substrate; the group III-V semiconductor substrate includes a gallium arsenide substrate, a gallium nitride substrate, or an indium phosphide substrate; and the group II-VI semiconductor substrate includes a cadmium telluride substrate or a zinc oxide substrate.

[0010] Preferably, the doping atoms in the doping source include Group VA atoms, Group IVA atoms, or Group IIIA atoms; the Group VA atoms include phosphorus atoms, arsenic atoms, antimony atoms, or bismuth atoms; the Group IVA atoms include silicon atoms, germanium atoms, tin atoms, or lead atoms; and the Group IIIA atoms include boron atoms, aluminum atoms, or gallium atoms.

[0011] Preferably, the doping source forms an SOD structure with the functional groups on the surface of the semiconductor substrate; the doping source includes an element or a compound corresponding to the doping atom; the compound corresponding to the doping atom includes an organic acid, an organic alcohol, or a metal alkyl compound corresponding to the doping atom.

[0012] Preferably, the elemental substance corresponding to the doped atom includes antimony metal, bismuth metal, tin metal, lead metal, or aluminum metal; the organic acid corresponding to the doped atom includes one or more of organophosphonic acid, organoarsonic acid, and organoboronic acid; and the organic alcohol corresponding to the doped atom includes organosilicon alcohol.

[0013] Preferably, the organophosphonic acid includes one or more of butylphosphonic acid, octylphosphonic acid, hexylphosphonic acid, dodecylphosphonic acid, phenylphosphonic acid, phenylphosphonium phosphonic acid, and dimethylphosphonic acid; the organoarsonic acid includes phenylarsonic acid and / or dimethylarsonic acid; the organosilicon alcohol includes trimethylsilanol and / or triethylsilanol; the organoboronic acid includes one or more of methylboronic acid, propylboronic acid, and phenylboronic acid; and the metal alkyl compound corresponding to the doped atom includes one or more of trimethylaluminum, trimethylgallium, and tetramethyltin.

[0014] Preferably, when the doping source is an element corresponding to the doping atom, the functional group modification is to form a hydroxyl structure on the surface of the semiconductor substrate; when the doping source is an organic acid or an organic alcohol corresponding to the doping atom, the functional group modification is to perform functional group modification of hydrogen atoms or halogen atoms on the surface of the semiconductor substrate; when the doping source is a metal alkyl compound corresponding to the doping atom, the functional group modification is to form a hydroxyl structure on the surface of the semiconductor substrate.

[0015] Preferably, when the doping source is an elemental substance corresponding to the doping atom, the process of bonding the doping source includes: placing the surface functionalized semiconductor substrate obtained by the functional group modification into the gaseous molecules of the doping source element to perform a surface chemical reaction; when the doping source is an organic acid or an organic alcohol corresponding to the doping atom, the process of bonding the doping source includes: placing the surface functionalized semiconductor substrate obtained by the functional group modification into the doping source solution to perform a substitution reaction; when the doping source is a metal alkyl compound of the doping atom, the process of bonding the doping source includes: placing the surface functionalized semiconductor substrate obtained by the functional group modification into the gaseous molecules of the doping source to perform a surface chemical reaction.

[0016] Preferably, the process of removing oxygen atoms from the SOD structure includes: depositing an active metal layer on the surface of the SOD structure, and then applying oxygen abstraction conditions to obtain a δ-doped semiconductor substrate.

[0017] Preferably, the metal-oxygen bond activity in the active metal layer is greater than the oxygen bond activity of the dopant atom.

[0018] This invention provides a method for delta-doping on the surface of a semiconductor substrate, comprising the following steps: modifying the surface of the semiconductor substrate with functional groups, bonding a dopant source through a surface chemical reaction to generate a superoxide dismutase (SOD) structure on the surface of the semiconductor substrate, and then removing oxygen atoms from the SOD structure to obtain a delta-doped semiconductor substrate; wherein S in the SOD structure represents an atom of the semiconductor substrate, O represents an oxygen atom, and D represents a dopant atom. The method of this invention covalently links dopant atoms to the semiconductor surface via oxygen atoms in an SOD structure. The impurity bonding process exhibits surface self-limitation, thus ensuring the fixation of a single layer of impurity atoms. Furthermore, during the removal of oxygen atoms from the SOD structure, the dopant atoms automatically enter the semiconductor lattice to become surface or subsurface atoms. This process can be achieved at low temperatures, thus suppressing the longitudinal diffusion of impurity atoms and allowing for more precise control of the doping depth. It is applicable to both planar and non-planar conformal doping without introducing lattice damage. It does not rely on high-temperature techniques such as laser annealing to activate impurities, can precisely control the doping depth, is compatible with CMOS processes, and is suitable for large-scale production. Attached Figure Description

[0019] Figure 1 The diagram below is a schematic diagram of the process of performing δ doping as described in Example 1, wherein: a is a schematic diagram of the structure of surface functional groups mainly composed of Ge-H obtained on the surface of the n-type germanium substrate; b is a schematic diagram of the connection of benzoarsine molecules on the surface of the surface-functionalized n-type germanium substrate; c is a schematic diagram of removing benzene rings and retaining the Ge-O-As structure on the surface of the n-type germanium substrate; d is a schematic diagram of depositing an aluminum layer on the surface of the As monolayer; e is a schematic diagram of the aluminum oxide film formed at the interface of the Al metal layer and the Ge layer; and f is a schematic diagram of δ doping of As atoms on the surface of the germanium substrate. Figure 2 The scanning transmission electron microscope (STEM) image (a) and X-ray energy dispersive spectroscopy (EDS) image (b) show the structure of the amorphous alumina thin film formed at the interface between the Al layer and the Ge layer in Example 1. Figure 3 This is a depth profile of the As-doped germanium substrate obtained by secondary ion mass spectrometry in Example 1. Figure 4 This is a schematic diagram of the process of δ-doping when the doping source is the element corresponding to the doping atom D. In this diagram, a is a schematic diagram of forming a hydroxyl structure on the surface of the semiconductor substrate, b is a schematic diagram of fixing the doping atom on the surface of the semiconductor substrate by SOD, c is a schematic diagram of removing oxygen atoms from the SOD structure, and d is a schematic diagram of obtaining a δ-doped semiconductor substrate with D atoms. Figure 5 This is a schematic diagram of the process of δ-doping when the doping source is an organic acid corresponding to the doping atom D or an organic alcohol corresponding to the doping atom. In this diagram, a is a schematic diagram of functional group modification of hydrogen atom or halogen atom on the surface of semiconductor substrate, b is a schematic diagram of fixing the doping atom on the surface of semiconductor substrate through SOD structure, c is a schematic diagram of removing organic group R on the substrate surface while retaining SOD structure, d is a schematic diagram of removing oxygen atom in SOD structure, and e is a schematic diagram of δ-doped semiconductor substrate. Figure 6 This is a schematic diagram of the process of δ-doping when the doping source is a metal alkyl compound corresponding to doping atom D. In the diagram, a is a schematic diagram of forming a hydroxyl structure on the surface of a semiconductor substrate, b is a schematic diagram of fixing doping atom D on the surface of the semiconductor substrate through a SOD structure, c is a schematic diagram of obtaining an SOD structure after removing the organic group R, d is a schematic diagram of removing oxygen atoms from the SOD structure, and e is a schematic diagram of a semiconductor substrate δ-doped with D atoms. Detailed Implementation

[0020] This invention provides a method for performing delta doping on the surface of a semiconductor substrate, comprising the following steps: After modifying the surface of a semiconductor substrate with functional groups, a doping source is bonded to it through a surface chemical reaction. After generating an SOD structure on the surface of the semiconductor substrate, the oxygen atoms in the SOD structure are removed to obtain a δ-doped semiconductor substrate. In the SOD structure, S represents atoms of the semiconductor substrate, O represents oxygen atoms, and D represents dopant atoms.

[0021] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0022] In this invention, the semiconductor substrate preferably comprises a group IV semiconductor substrate, a group III-V semiconductor substrate, or a group II-VI semiconductor substrate; the group IV semiconductor substrate preferably comprises a silicon substrate, a germanium substrate, a silicon-germanium alloy substrate, or a germanium-tin alloy substrate; the group III-V semiconductor substrate preferably comprises a gallium arsenide substrate, a gallium nitride substrate, or an indium phosphide substrate; and the group II-VI semiconductor substrate preferably comprises a cadmium telluride substrate or a zinc oxide substrate. In this invention, the semiconductor material in the semiconductor substrate is preferably in the form of a bulk material, a thin film, or a nanostructure.

[0023] Before performing the surface functional group modification, the present invention preferably includes cleaning the semiconductor substrate. The present invention does not impose any special limitations on the cleaning process; a standard cleaning procedure well known to those skilled in the art can be used. In an embodiment of the present invention, the cleaning may involve ultrasonically cleaning the n-type germanium substrate sequentially in CMOS-grade acetone, isopropanol, and ethanol for 5 minutes.

[0024] In this invention, the doping atoms in the doping source preferably include Group VA, Group IVA, or Group IIIA atoms; the Group VA atoms preferably include phosphorus (P), arsenic (As), antimony (Sb), or bismuth (Bi); the Group IVA atoms preferably include silicon (Si), germanium (Ge), tin (Sn), or lead (Pb); and the Group IIIA atoms preferably include boron (B), aluminum (Al), or gallium (Ga). In this invention, the doping source preferably includes the elemental substance corresponding to the doping atom or the compound corresponding to the doping atom; when the doping source is the elemental substance corresponding to the doping atom, the doping source preferably includes antimony metal, bismuth metal, tin metal, lead metal, or aluminum metal; the purity of the elemental substance corresponding to the doping atom is preferably high-purity. When the doping source is a compound corresponding to a doping atom, the compound corresponding to the doping atom preferably includes an organic acid, an organic alcohol, or a metal alkyl compound corresponding to the doping atom; the organic acid or organic alcohol corresponding to the doping atom preferably contains a hydroxyl structure; the organic acid corresponding to the doping atom includes one or more of organophosphonic acid, organoarsonic acid, and organoboric acid; the organophosphonic acid preferably includes one or more of butylphosphonic acid, octylphosphonic acid, hexylphosphonic acid, dodecylphosphonic acid, phenylphosphonic acid, phenylphosphine, and dimethylphosphonic acid; the organoarsonic acid preferably includes phenylarsonic acid and / or dimethylarsonic acid; the organoboric acid preferably includes one or more of methylboronic acid, propylboronic acid, and phenylboronic acid. The organic alcohol corresponding to the doping atom preferably includes organosilicon alcohol, and the organosilicon alcohol preferably includes trimethylsilanol and / or triethylsilanol. The metal alkyl compound corresponding to the doping atom preferably includes one or more of trimethylaluminum, trimethylgallium, and tetramethyltin.

[0025] In this invention, the process of modifying the surface functional groups and bonding the dopant source is preferably adaptively adjusted according to the type of dopant source. Specifically: When the doping source is an element corresponding to the doping atom, the surface functional group modification is preferably the formation of a hydroxyl structure (e.g., ...) on the surface of the semiconductor substrate. Figure 4 (as shown in a) The present invention does not impose any particular limitation on the process of forming the hydroxyl structure on the surface of the semiconductor substrate, and any process well known to those skilled in the art can be used. For example, when the semiconductor substrate is a germanium semiconductor substrate, the germanium semiconductor substrate is etched in hydrofluoric acid with a mass concentration of 0.5% to form a hydroxyl structure (Ge-OH) on the surface of the germanium semiconductor substrate.

[0026] After forming a hydroxyl structure on the surface of the semiconductor substrate, it is preferable to utilize the affinity between the dopant atoms and oxygen atoms to fix the dopant atoms on the surface of the semiconductor substrate through a chemical reaction (e.g., ...). Figure 4(as shown in b in the text).

[0027] In this invention, the preferred method for bonding the dopant source via surface chemical reaction is to place the surface-functionalized semiconductor substrate (obtained by the functional group modification) into the gaseous molecules of the dopant source element for a surface chemical reaction. Preferably, the temperature of the surface chemical reaction is higher than the melting point temperature of the element corresponding to the dopant source.

[0028] In this invention, controlling the temperature at which the dopant atoms are fixed on the surface of the semiconductor substrate ensures that the bonding between the dopant atoms and the oxygen atoms on the semiconductor substrate surface is more stable than the bonding between the dopant atoms themselves, thereby ensuring the adsorption of a self-confined monolayer of dopant atoms on the semiconductor substrate surface. Therefore, the above process exhibits surface self-confinence.

[0029] In this invention, the process of removing oxygen atoms from the SOD structure (such as...) Figure 4 (as shown in c) preferably includes: After depositing an active metal layer on the surface of the SOD structure, oxygen abstraction conditions are applied to obtain a δ-doped semiconductor substrate (such as...). Figure 4 (as shown in d).

[0030] In this invention, the deposition method is preferably physical vapor deposition. This invention does not impose any special limitations on the physical vapor deposition process, and any process well known to those skilled in the art can be used.

[0031] In this invention, the thickness of the active metal layer is preferably ≥10 nm.

[0032] In this invention, the reactivity of the metal bonded to oxygen in the active metal layer is preferably greater than the reactivity of the dopant atom bonded to oxygen. In this invention, the metal in the active metal layer preferably includes one or more of aluminum, magnesium, zinc, and titanium.

[0033] In this invention, the oxygen deprivation condition is preferably room temperature (i.e., no additional heating or cooling is required).

[0034] In this invention, by controlling the above-mentioned oxygen-absorption conditions, unnecessary oxygen atoms on the surface can be removed, while at the same time, dopant atoms enter the semiconductor lattice to achieve low-temperature δ-doping.

[0035] When the doping source is an organic acid or an organic alcohol corresponding to the doping atom, the surface functional group modification is preferably performed on the surface of the semiconductor substrate by modifying the functional groups of hydrogen atoms or halogen atoms (e.g., Figure 5 (as shown in a) This invention does not impose any particular limitation on the process of modifying the functional groups of hydrogen atoms or halogen atoms on the surface of the semiconductor substrate; any process well known to those skilled in the art can be used. For example, when the semiconductor substrate is a silicon semiconductor substrate, the silicon semiconductor substrate is etched in hydrofluoric acid with a mass concentration of 0.5% to 1% to form a Si-H structure on the surface of the silicon semiconductor substrate; when the semiconductor substrate is a germanium semiconductor substrate, the germanium semiconductor substrate is etched in hydrofluoric acid with a mass concentration of 49% to form a Ge-H structure on the surface of the germanium semiconductor substrate; when the semiconductor substrate is a germanium semiconductor substrate, the germanium semiconductor substrate is etched in hydrochloric acid with a mass concentration of 10% to form a Ge-Cl structure on the surface of the germanium semiconductor substrate.

[0036] After functional group modification with hydrogen or halogen atoms on the surface of the semiconductor substrate, the doped atoms are preferably fixed on the surface of the semiconductor substrate through a chemical reaction (e.g., Figure 5 (as shown in b in the text).

[0037] In this invention, the process of fixing the doped atoms on the surface of the semiconductor substrate is preferably as follows: The semiconductor substrate with modified surface functional groups is placed in a doping source solution to undergo a substitution reaction.

[0038] In this invention, the concentration of the dopant source in the dopant source solution is preferably ≥5 mmol / L.

[0039] In this invention, the temperature of the substitution reaction is preferably 65~165℃, more preferably 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, or 165℃; the time is preferably 2~24h, more preferably 2h, 5h, 10h, 15h, 20h, or 24h. In this invention, the temperature of the substitution reaction is preferably adaptively adjusted within the above temperature range according to the material of the semiconductor substrate and the type of dopant source. For example, when the semiconductor substrate modified with surface functional groups is a silicon substrate with a Si-H structure on the surface and the doping source is an organophosphonic acid, the temperature of the substitution reaction is preferably 65~130℃; when the semiconductor substrate modified with surface functional groups is a germanium substrate with a Ge-H structure on the surface and the doping source is an organoarsonic acid, the temperature of the substitution reaction is preferably 80~130℃.

[0040] In this invention, the substitution reaction has surface self-limiting properties, which can ensure the connection of a single layer of doped atoms on the semiconductor surface.

[0041] After the substitution reaction is completed, the present invention preferably further includes removing the organic groups in the dopant source to obtain an SOD structure (e.g., Figure 5 (as shown in c) The preferred method for removing the organic groups from the dopant source is heating; in this invention, the heating temperature preferably depends on the bonding strength between the dopant atom and the organic group; when the dopant source is an organophosphonic acid, the heating temperature is preferably 450~550℃, more preferably 450℃, 470℃, 490℃, 510℃, 530℃ or 550℃; when the dopant source is an organoarsonic acid, the heating temperature is preferably 500~750℃, more preferably 500℃, 550℃, 600℃, 650℃, 700℃ or 750℃; when the dopant source is an organosilicon alcohol, the heating temperature is preferably 300℃; when the dopant source is boric acid, the heating temperature is preferably 600℃.

[0042] In this invention, the process of removing oxygen atoms from the SOD structure (such as...) Figure 5 (as shown in d) preferably includes: After depositing an active metal layer on the surface of the SOD structure, oxygen abstraction conditions are applied to obtain a δ-doped semiconductor substrate (such as...). Figure 5 (as shown in e).

[0043] In this invention, the deposition method is preferably physical vapor deposition. This invention does not impose any special limitations on the physical vapor deposition process, and any process well known to those skilled in the art can be used.

[0044] In this invention, the thickness of the active metal layer is ≥10nm.

[0045] In this invention, the reactivity of the metal in the active metal layer with oxygen bonding is preferably superior to the reactivity of the semiconductor material in the semiconductor substrate with oxygen bonding. In this invention, the metal in the active metal layer preferably includes one or more of aluminum, magnesium, zinc, and titanium.

[0046] In this invention, the oxygen deprivation condition is preferably room temperature (i.e., no additional heating or cooling is required).

[0047] In this invention, a metal thin film with better affinity for oxygen is used. Under normal room temperature conditions, the metal thin film can form more stable chemicals with oxygen in SOD. By controlling the aforementioned oxygen abstraction conditions, unwanted oxygen atoms on the surface can be removed, while simultaneously dopant atoms enter the semiconductor lattice, achieving low-temperature delta doping.

[0048] When the doping source is a metal alkyl compound corresponding to the doping atom, the surface functional group modification is to form a hydroxyl structure (e.g., ...) on the surface of the semiconductor substrate. Figure 6 (as shown in a).

[0049] The present invention does not impose any particular limitation on the process of forming the hydroxyl structure on the surface of the semiconductor substrate, and any process well known to those skilled in the art can be used. For example, when the semiconductor substrate is a germanium semiconductor substrate, the germanium semiconductor substrate is etched in hydrofluoric acid with a mass concentration of 0.5% to form a hydroxyl structure (Ge-OH) on the surface of the germanium semiconductor substrate.

[0050] In this invention, when the doping source is a doped atom metal alkyl compound, the process of bonding the doping source includes: placing the surface functional group-modified semiconductor substrate obtained by the functional group modification into the gaseous molecules of the doping source to perform a surface chemical reaction (e.g., ... Figure 6 (as shown in b in the text).

[0051] In this invention, the temperature of the surface chemical reaction is preferably greater than or equal to the gaseous temperature of the doped atom metal alkyl compound.

[0052] In this invention, the surface chemical reaction is preferably a ligand exchange reaction, which has surface self-limiting properties and can ensure the connection of a single layer of doped atoms on the semiconductor surface.

[0053] After the surface chemical reaction is completed, the present invention preferably further includes removing organic groups from the dopant source to obtain an SOD structure (such as...). Figure 6 (as shown in c in the diagram).

[0054] In this invention, the organic groups in the dopant source are preferably removed by heating, and the heating temperature preferably depends on the bonding strength between the dopant atom and the organic group. When the doping source is trimethylaluminum, the heating temperature is preferably 150~350℃, more preferably 150℃, 175℃, 200℃, 225℃, 250℃, 275℃, 300℃, 325℃ or 350℃; when the doping source is trimethylgallium, the heating temperature is preferably 180~250℃, more preferably 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃ or 250℃; when the doping source is tetra(dimethylamino)tin, the heating temperature is preferably 150~250℃, more preferably 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃ or 250℃.

[0055] In this invention, the process of removing oxygen atoms from the SOD structure (such as...) Figure 6 (as shown in d) preferably includes: After depositing an active metal layer on the surface of the SOD structure, oxygen abstraction conditions are applied to obtain a δ-doped semiconductor substrate (such as...). Figure 6(as shown in e).

[0056] In this invention, the deposition method is preferably physical vapor deposition. This invention does not impose any special limitations on the physical vapor deposition process, and any process well known to those skilled in the art can be used.

[0057] In this invention, the thickness of the active metal layer is ≥10nm.

[0058] In this invention, the reactivity of the metal in the active metal layer with oxygen bonding is preferably superior to the reactivity of the semiconductor material in the semiconductor substrate with oxygen bonding. In this invention, the metal in the active metal layer preferably includes one or more of aluminum, magnesium, zinc, and titanium.

[0059] In this invention, the oxygen deprivation condition is preferably room temperature (i.e., no additional heating or cooling is required).

[0060] In this invention, a metal thin film with better affinity for oxygen is used. Under normal room temperature conditions, the metal thin film can form more stable chemicals with oxygen in SOD. By controlling the aforementioned oxygen abstraction conditions, unwanted oxygen atoms on the surface can be removed, while simultaneously dopant atoms enter the semiconductor lattice, achieving low-temperature delta doping.

[0061] In this invention, the oxygen abstraction temperature in the above three cases is much lower than the temperature required for lattice repair in semiconductor thermal diffusion doping or ion implantation doping, as well as the temperature reached during laser annealing. The doping process described in this invention ensures precise control of the position of impurity atoms during the doping process.

[0062] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0063] Example 1 Semiconductor substrate: n-type germanium substrate (crystal orientation) <100> (Thickness is 500μm±25μm, resistivity is 8~40Ω·cm). Dopant source: benzoarsine (doped with arsenic atoms) Methods for performing delta doping (e.g.) Figure 1 (as shown) 1) The n-type germanium substrate was sequentially ultrasonically cleaned in CMOS-grade acetone, isopropanol, and ethanol for 5 minutes. The ethanol on the surface of the n-type germanium substrate was then rinsed off with deionized water and dried with nitrogen gas to obtain a cleaned n-type germanium substrate. In a fume hood or glove box, the cleaned n-type germanium substrate was etched in 49% hydrofluoric acid for 5 minutes and dried with nitrogen gas. This resulted in a surface functional group dominated by Ge-H (i.e., a surface-functionalized n-type germanium substrate, such as…) on the surface of the n-type germanium substrate. Figure 1 (as shown in a) 2) such as Figure 1 As shown in b, the surface-functionalized n-type germanium substrate is rapidly placed in a mixture of benzoarsine and anhydrous anisole (0.015 g of benzoarsine and 2 mL of anhydrous anisole). Under an anhydrous and oxygen-free environment (provided by a vacuum double-row tube or vacuum glove box), it is heated at 130°C for 3 hours. (During this process, the hydroxyl groups in benzoarsine react chemically with the Ge-H on the substrate surface, causing As atoms to covalently connect to the germanium surface through the Ge-O-As structure). After naturally cooling to room temperature under an anhydrous and oxygen-free condition, the n-type germanium substrate with the Ge-O-As structure is removed. It is then thoroughly cleaned sequentially with anisole, acetone, and alcohol to remove the physically adsorbed anisole and benzoarsine molecules from its surface, ultimately leaving a monolayer of benzoarsine on its surface, thus obtaining the Ge-O-As structure. 3) In a mixture of argon and hydrogen with a volume ratio of 96:4, the Ge-O-As structure was heated at 550°C for 10 min to break the As-C bond between As and the benzene ring, releasing the benzene ring. Afterward, it was cooled further in the same 96:4 argon-hydrogen mixture to obtain the structure shown below. Figure 1 The structure shown in c (where As is a single atomic layer in the Ge-O-As structure); 4) Deposit a 100 nm aluminum layer (e.g., on the surface of the As single-atom layer in the Ge-O-As structure) Figure 1 As shown in d), under natural conditions, due to Al's greater affinity for oxygen atoms, the Al layer reacts with the oxygen in the Ge-O-As structure to form an amorphous aluminum oxide film (AlO) at the interface between the Al metal layer and the Ge layer. x Thin films, such as Figure 1 (as shown in e in the figure), at the same time, As atoms enter the Ge lattice and become surface or subsurface atoms; 5) The aluminum layer and AlO were removed using a 2.4% tetramethylammonium hydroxide (TMAH) solution. x Thin film, to obtain As-doped germanium substrate (e.g. Figure 1 (as shown in f in the text). Figure 2The images shown are STEM (a) and X-ray energy dispersive spectroscopy (EDS) images (b) of the amorphous alumina thin film formed at the interface between the Al and Ge layers in Example 1. Figure 2 It can be seen that after depositing an Al layer on the surface of the As single-atom layer in the Ge-O-As structure, an oxide layer of approximately 2.5 nm is formed between the Al layer and germanium; wherein Figure 2 EDS scanning along the direction of the arrow in section a confirms that the oxide layer is composed of AlO. x No GeO was observed. x The presence of the layer indicates that oxygen atoms in the Ge-O-As structure are consumed through the oxidation process of the aluminum layer (aluminum electrode). Figure 3 To obtain a depth profile of the As-doped germanium substrate obtained by secondary ion mass spectrometry, the following methods were employed: Figure 3 It can be seen that the concentration of As atoms is 8 × 10⁻⁶ at the surface. 19 cm -3 Attenuation to a depth of 2.5 nm at 8×10 18 cm -3 This proves that δ doping has been achieved.

[0064] Example 2 Semiconductor substrate: n-type silicon substrate (crystal orientation) <100> (Thickness is 500μm±25μm, resistivity is 1~3Ω·cm). Dopant source: benzoarsine (doped with arsenic atoms) Methods for performing delta doping (e.g.) Figure 5 (as shown) 1) The n-type silicon substrate was ultrasonically cleaned sequentially in CMOS-grade acetone, isopropanol, and ethanol for 5 minutes. Then, the ethanol on the surface of the n-type silicon substrate was rinsed off with deionized water and dried with nitrogen to obtain a cleaned n-type silicon substrate. In a fume hood or glove box, the cleaned n-type silicon substrate was etched in 1% hydrofluoric acid for 5 minutes and dried with nitrogen to obtain a surface functional group mainly composed of Si-H (i.e., a surface-functionalized n-type silicon substrate) on the surface of the n-type silicon substrate. 2) The surface-functionalized n-type silicon substrate is rapidly placed into a mixture of benzoarsine and anhydrous anisole (0.015 g of benzoarsine and 2 mL of anhydrous anisole). Under an anhydrous and oxygen-free environment (provided by a vacuum double-row tube or vacuum glove box), it is heated at 130°C for 3 hours (during this process, the hydroxyl groups in benzoarsine react chemically with the Si-H on the substrate surface, causing As atoms to be covalently bonded to the silicon surface through the Si-O-As structure). After naturally cooling to room temperature under anhydrous and oxygen-free conditions, the n-type silicon substrate with the Si-O-As structure is removed and thoroughly cleaned with anisole, acetone and alcohol in sequence to remove the physically adsorbed anisole and benzoarsine molecules on its surface, ultimately leaving a monolayer of benzoarsine on its surface. 3) In a mixture of argon and hydrogen with a volume ratio of 96:4, the benzoarsine monolayer structure is heated at 450°C for 1 min to break the As-C bond between As and the benzene ring, releasing the benzene ring. Then, it is cooled in the mixture of argon and hydrogen with a volume ratio of 96:4 to obtain a Si-O-As structure on the silicon surface, wherein As is a single atomic layer. 4) A 100 nm aluminum layer is deposited on the surface of the As monolayer in the Si-O-As structure. Then, under natural conditions, because Al has a greater affinity for oxygen atoms, the Al layer reacts with the oxygen in the Si-O-As structure to form an amorphous aluminum oxide film (AlO) at the interface between the Al metal layer and the silicon layer. x Meanwhile, As atoms enter the Si lattice and become surface atoms; 5) The aluminum layer and AlO were removed using a 2.4% tetramethylammonium hydroxide (TMAH) solution. x Thin film, to obtain As-doped silicon substrate; Depth profiling of the As-doped silicon substrate using secondary ion mass spectrometry revealed that As atoms achieved delta doping within 1 nm of the silicon surface, with a doping concentration of 4.9 × 10⁻⁶. 20 cm -3 .

[0065] Example 3 Semiconductor substrate: n-type germanium substrate (crystal orientation) <100> (Thickness is 500μm±25μm, resistivity is 8~40Ω·cm). Doping source: High-purity Sb metal (doped with antimony atoms) Methods for performing delta doping (e.g.) Figure 4 (as shown) 1) The n-type germanium substrate was ultrasonically cleaned in CMOS-grade acetone, isopropanol and ethanol for 5 min in sequence. Then, the ethanol on the surface of the n-type germanium substrate was rinsed off with deionized water and dried with nitrogen to obtain the cleaned n-type germanium substrate. The cleaned n-type germanium substrate was etched in 1% hydrofluoric acid for 5 min, rinsed with deionized water and dried with nitrogen to obtain a surface functional group mainly composed of Ge-OH on the surface of the n-type germanium substrate, that is, a surface functionalized n-type germanium substrate. 2) The surface-functionalized n-type germanium substrate is rapidly placed into a thermal evaporation coating system, and an 8 nm Sb thin film is deposited at a rate of approximately 0.5 nm / s using high-purity Sb metal as the evaporation source.

[0066] 3) In a mixture of argon and hydrogen with a volume ratio of 96:4, the germanium substrate with the Sb thin film was heated at 300°C for 10 min, causing the Sb atoms to react with the Ge-OH structure on the germanium surface to form a Ge-O-Sb structure. At 300°C, the bonds between Sb atoms are relatively weak, thus excess Sb atoms are evaporated.

[0067] 4) A 100 nm aluminum layer is deposited on the surface of the Sb monolayer in the Ge-O-Sb structure. Then, under natural conditions, because Al has a greater affinity for oxygen atoms, the Al layer reacts with the oxygen in the Ge-O-Sb structure to form an amorphous aluminum oxide film (AlO) at the interface between the Al metal layer and the Ge layer. x (Thin film), at the same time, Sb atoms enter the Ge lattice and become surface atoms; 5) The aluminum layer and AlO were removed using a 2.4% tetramethylammonium hydroxide (TMAH) solution. x Thin film, to obtain a germanium substrate with Sb doped surface; Depth profiling of the Sb-doped silicon substrate using secondary ion mass spectrometry revealed that Sb atoms achieved delta doping within 1 nm of the silicon surface, with a doping concentration of 1.5 × 10⁻⁶. 22 cm -3 .

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for performing delta doping on the surface of a semiconductor substrate, characterized in that, Includes the following steps: After modifying the surface of a semiconductor substrate with functional groups, a doping source is bonded to it through a surface chemical reaction. After generating an SOD structure on the surface of the semiconductor substrate, the oxygen atoms in the SOD structure are removed to obtain a δ-doped semiconductor substrate. In the SOD structure, S represents atoms of the semiconductor substrate, O represents oxygen atoms, and D represents dopant atoms; The process of removing oxygen atoms from the SOD structure includes: depositing an active metal layer on the surface of the SOD structure, and then applying oxygen abstraction conditions to obtain a δ-doped semiconductor substrate; The metal in the active metal layer exhibits greater reactivity with oxygen bonding than the dopant atoms. The oxygen-absorption temperature is room temperature.

2. The method as described in claim 1, characterized in that, The semiconductor substrate includes a group IV semiconductor substrate, a group III-V semiconductor substrate, or a group II-VI semiconductor substrate; The group IV semiconductor substrate includes a silicon substrate, a germanium substrate, a silicon-germanium alloy substrate, or a germanium-tin alloy substrate; The group III-V semiconductor substrate includes a gallium arsenide substrate, a gallium nitride substrate, or an indium phosphide substrate; The group II-VI semiconductor substrate includes a cadmium telluride substrate or a zinc oxide substrate.

3. The method as described in claim 1, characterized in that, The doping atoms in the doping source include Group VA atoms, Group IVA atoms, or Group IIIA atoms; The Group VA atoms include phosphorus atoms, arsenic atoms, antimony atoms, or bismuth atoms; The group IVA atoms include silicon atoms, germanium atoms, tin atoms, or lead atoms; The group IIIA atoms include boron atoms, aluminum atoms, or gallium atoms.

4. The method as described in claim 3, characterized in that, The doping source forms an SOD structure with the functional groups on the surface of the semiconductor substrate; The doping source includes the elemental substance corresponding to the doping atom or the compound corresponding to the doping atom; The compounds corresponding to the doped atoms include organic acids, organic alcohols, or metal alkyl compounds corresponding to the doped atoms.

5. The method as described in claim 4, characterized in that, The elemental substances corresponding to the doped atoms include antimony, bismuth, tin, lead, or aluminum. The organic acids corresponding to the doped atoms include one or more of organophosphonic acids, organoarsonic acids, and organoboronic acids; The organic alcohols corresponding to the doped atoms include organosilicon alcohols.

6. The method as described in claim 5, characterized in that, The organophosphonic acid includes one or more of butylphosphonic acid, octylphosphonic acid, hexylphosphonic acid, dodecylphosphonic acid, phenylphosphonic acid, phenylphosphonic acid, and dimethylphosphonic acid; The organic arsanoic acid includes phenylarsanoic acid and / or dimethylarsanoic acid; The organosilanols include trimethylsilanol and / or triethylsilanol; the organoboronic acids include one or more of methylboronic acid, propylboronic acid, and phenylboronic acid. The metal alkyl compounds corresponding to the doped atoms include one or more of trimethylaluminum, trimethylgallium, and tetramethyltin.

7. The method as described in claim 4, characterized in that, When the doping source is an element corresponding to the doping atom, the functional group modification is to form a hydroxyl structure on the surface of the semiconductor substrate; When the doping source is an organic acid or an organic alcohol corresponding to the doping atom, the functional group modification is to modify the functional group of hydrogen atom or halogen atom on the surface of the semiconductor substrate. When the doping source is a metal alkyl compound corresponding to the doping atom, the functional group modification is to form a hydroxyl structure on the surface of the semiconductor substrate.

8. The method as described in claim 7, characterized in that, When the doping source is an elemental substance corresponding to the doping atom, the process of bonding the doping source includes: placing the surface functional group modified semiconductor substrate obtained by the functional group modification into the gaseous molecules of the doping source elemental substance to carry out a surface chemical reaction. When the doping source is an organic acid or an organic alcohol corresponding to a doping atom, the process of bonding the doping source includes: placing the surface functional group modified semiconductor substrate obtained by the functional group modification into the doping source solution for a substitution reaction. When the doping source is a doped atomic metal alkyl compound, the process of bonding the doping source includes: placing the surface functional group modified semiconductor substrate obtained by the functional group modification into the gaseous molecules of the doping source to carry out a surface chemical reaction.

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