Feedforward device fabrication

Abstract

A method includes: forming an opening (204) in a mask layer (202); measuring a feature size associated with the size of the opening (206); determining manufacturing parameters based on the feature size; and forming a second layer (212) in the opening. The second layer is formed based on the manufacturing parameters. A manufacturing system includes a lithography system, a measurement system, a physical vapor deposition system, an oxidation system, and a control system. The control system is configured to control the feed-forward manufacturing process.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application No. 17 / 883,475, filed on August 8, 2022. Technical Field

[0003] The present disclosure relates to fabrication processes for devices such as qubits. Background Art

[0004] Masking and layer formation processes can be used to define fabricated structures, thereby forming parts of devices for applications such as quantum computing. Summary of the invention

[0005] Some aspects of the present disclosure describe a manufacturing method. According to the manufacturing method, an opening is formed in a mask layer. A feature size associated with a size of the opening is measured. A manufacturing parameter is determined based on the feature size. A second layer is formed in the opening. The forming of the second layer is based on the manufacturing parameter.

[0006] The methods of the present invention and other disclosed methods may have at least any one or more of the following characteristics.

[0007] In some implementations, the second layer includes an oxide layer, and the fabrication parameters include oxide growth parameters.

[0008] In some implementations, forming the second layer includes: forming the first layer in the opening; and forming an oxide layer on the first layer.

[0009] In some implementations, forming the second layer includes growing an oxide layer by oxidizing the first layer based on oxide growth parameters.

[0010] In some implementations, the first layer includes a metal, and the method includes, after forming the oxide layer, forming a third layer on the oxide layer to form a Josephson junction.

[0011] In some implementations, the method includes forming a qubit including a Josephson junction.

[0012] In some implementations, forming the first layer includes depositing the first layer at a first deposition angle, and forming the third layer includes depositing the third layer at a second deposition angle different from the first deposition angle.

[0013] In some implementations, the metal includes a superconductor material.

[0014] In some implementations, forming the second layer includes exposing the first layer to an oxidizing gas at a partial pressure for a period of time, and the oxide growth parameter includes the partial pressure.

[0015] In some implementations, forming the second layer includes exposing the first layer to an oxidizing gas at a partial pressure for a period of time, and the oxide growth parameters include the period of time.

[0016] In some implementations, the method includes forming a circuit element including a second layer and a first layer on which the second layer is disposed. Determining a manufacturing parameter includes: obtaining a target resonant frequency of the circuit element or a target critical current of the circuit element; determining a junction area based on the measured feature size; and determining a value of the manufacturing parameter based on the junction area that, when applied during formation of the second layer, causes the circuit element to exhibit the target resonant frequency or the target critical current.

[0017] In some implementations, determining the manufacturing parameter includes: obtaining a target thickness of the second layer that enables the circuit element to have a target resonant frequency or a target critical current; and determining a value of the manufacturing parameter that enables the second layer to have the target thickness.

[0018] In some implementations, measuring the feature size includes measuring a size of the opening.

[0019] In some implementations, measuring the feature size includes measuring a dimension of a calibration structure defined by the mask layer. The calibration structure is distinct from the opening.

[0020] In some implementations, determining the manufacturing parameters includes: determining that the feature size is greater than a predetermined feature size, and in response to determining that the feature size is greater than the predetermined feature size, selecting the manufacturing parameters so that the thickness of the second layer is thicker than a first thickness associated with the predetermined feature size; or, determining that the feature size is less than the predetermined feature size, and in response to determining that the feature size is less than the predetermined feature size, selecting the manufacturing parameters so that the thickness of the second layer is thinner than the first thickness associated with the predetermined feature size.

[0021] In some implementations, measuring the feature size includes measuring the feature size using an atomic force microscope.

[0022] Some aspects of the present disclosure describe a manufacturing system. The manufacturing system includes a lithography system, a measurement system, a physical vapor deposition system, an oxidation system, and a control system. The control system is configured to perform operations, the operations including: causing the lithography system to form an opening in a mask layer; causing the measurement system to measure a feature size associated with a size of the opening; determining an oxide growth parameter based on the feature size; causing the physical vapor deposition system to deposit a first metal layer in the opening; causing the oxidation system to oxidize a portion of the first metal layer based on the oxide growth parameter to form an oxide layer on the first metal layer; and causing the physical vapor deposition system to deposit a second metal layer on the oxide layer.

[0023] The manufacturing system of the present invention and other disclosed manufacturing systems may have at least any one or more of the following characteristics.

[0024] In some implementations, causing the oxidation system to oxidize a portion of the first metal layer includes causing the oxidation system to expose the first metal layer to an oxidizing gas for a period of time, and the oxide growth parameter includes the period of time.

[0025] In some implementations, the first metal layer, the oxide layer, and the second metal layer form a Josephson junction below a critical temperature, and the operations include: obtaining a target resonant frequency of a qubit including a Josephson junction or a target critical current of a Josephson junction; determining a junction area element based on the measured feature size; and determining a value of an oxide growth parameter based on the junction area that, when applied during formation of the oxide layer, causes the qubit to exhibit the target resonant frequency or causes the Josephson junction to exhibit the target critical current.

[0026] In some implementations, measuring the feature size includes measuring a size of the opening or measuring a size of a calibration structure defined by the mask layer. The calibration structure is distinct from the opening.

[0027] Implementations according to the present disclosure may be used to achieve one or more advantages. In some implementations, device performance and yield may be improved by reducing changes in device parameters compared to devices that do not compensate for changes. In some implementations, the manufacture of the device may be modified in manufacturing based on measurements of the device itself or corresponding calibration structures, thereby reducing manufacturing costs, manufacturing complexity, and / or delays associated with feedback methods or post-manufacturing processing. In some implementations, device contamination may be reduced compared to methods that rely on post-manufacturing processing.

[0028] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram illustrating an example of a manufacturing process.

[0030] FIG. 2A to FIG. 2D is a schematic diagram showing an example of a layer structure.

[0031] FIG. 3A to FIG. 3B is a schematic diagram showing an example of oxide growth.

[0032] Figure 4 is a schematic diagram showing an example of an opening and a calibration structure.

[0033] FIG. 5A to FIG. 5D is a schematic diagram illustrating an example of a manufacturing process.

[0034] FIG. 6A to FIG. 6D is a schematic diagram illustrating an example of a quantum bit.

[0035] Figure 7 is a schematic diagram illustrating an example of a manufacturing system.

[0036] Specific implementation method

[0037] The present disclosure relates to "feedforward" manufacturing processes. In terms of the response of typical device manufacturing processes to process variations, drifts, and errors, these processes are often "feedback", meaning that the measured results of the process are used to inform subsequent iterations of the process. For example, if a doping process is found to cause the conductivity of a sample to be higher than a desired value, the doping process can be adjusted for subsequent processing so that subsequent samples have lower conductivity. However, in this example of a feedback process, samples with excessively high conductivity are not processed differently based on the measured conductivity: either the sample is discarded, or the sample is processed conventionally regardless of the measured conductivity. In processes with a high degree of variation, this feedback approach can result in unacceptably low yields and high costs associated with "out of specification" samples.

[0038] In contrast, according to implementations of the present disclosure, a feed-forward approach is used for changes in the feature size of features within an existing layer. In a specific example, the feature size can be related to the size of the opening, and the existing layer can include, for example, a mask layer. Based on measurements indicating the feature size in a specific sample, the specific sample is treated differently in subsequent processing steps to compensate for changes in the feature size. Therefore, changes in device parameters during the process can be reduced and yield can be improved. In some implementations of the present disclosure, the feed-forward approach includes adjustment of oxide growth parameters so that parameters of the oxide (e.g., the thickness of the oxide) are adjusted to compensate for changes in the feature size (e.g., the size of the opening).

[0039] Figure 1 An example of a feed-forward manufacturing process 100 is shown. In process 100, a feature is formed in an initial layer (102). For example, the first feature may include an opening. Additionally or alternatively, in some implementations, the initial layer is or includes a mask layer. For example, Figure 2AAs shown, an opening 204 is formed in a mask layer 202 disposed on a substrate 200. In various implementations, the mask layer 202 and the substrate 200 may have various compositions. In some implementations, the substrate 200 is a semiconductor substrate, such as a silicon substrate. In some implementations, the substrate 200 is a dielectric substrate, such as a glass substrate or a sapphire substrate. In some implementations, the substrate 200 includes a plurality of materials, such as a plurality of layers composed of different materials, for example, a silicon oxide layer located on an underlying silicon substrate. In some implementations, the mask layer 202 is a photoresist layer or includes a photoresist layer, and forming the opening 204 may include performing photolithography on the mask layer 202 (e.g., developing after exposing the mask). In some implementations, the mask layer 202 is or includes a "hard mask" layer, for example, an oxide or other dielectric layer (such as a thermal oxide layer, a chemical vapor deposited oxide layer, or a nitride layer), a metal layer, a semiconductor layer (such as a chemical vapor deposited polysilicon layer), an organic layer (such as a plastic layer or a polymer layer, for example, a polymethyl methacrylate (PMMA) layer), or a combination of these types of layers. For example, in some implementations, the mask layer 202 includes a semiconductor layer disposed on an oxide layer, an oxide layer disposed on a metal layer (e.g., a niobium oxide layer disposed on a niobium layer), or an organic layer disposed on one or more layers. In some implementations, the mask layer 202 includes a suspended portion, such as for a Dolan-type manufacturing process. In some implementations, the opening 204 in the mask layer 202 includes an undercut.

[0040] Other types of features may include, for example, ridges, grooves, bumps, protrusions, pads, and / or cylinders (eg, in an array of cylinders).Such features may be formed in or defined by the initial layer.

[0041] Forming features in the initial layer may include one or more of a variety of processes. For example, forming features may include forming openings 204 in mask layer 202, such as through masked deposition (eg, evaporation through a shadow mask), photolithography, and / or etching of mask layer 202.

[0042] The formation of features in the initial layer is subject to variations that cannot be predicted in advance. For example, the dimensions of the features (e.g., the dimension 206 of the opening 204), such as the radius, diameter, depth, height, width, and / or length of the features, may vary by 5%, 10%, 20%, or more. The variation in the dimension 206 may be associated with variations in the processing environment (e.g., temperature and / or humidity), variations in the location of the opening 204 (e.g., the location of the opening 204 on the substrate 200 and / or the location of the opening 204 relative to the sample handling system, such as the location of the opening 204 on a platen or chuck of a deposition or etching system), variations in chemical concentration / composition, variations in the exposure of the photoresist (such as some implementations of the mask layer 202), such as overdosing / underdosing, variations in the development of the photoresist, and / or another type of process variation. Process variation may be exacerbated for features with high aspect ratios (e.g., a high ratio of the thickness of the mask layer 202 to the dimension 206 of the opening 204). For example, high aspect ratios can occur in dual angle deposition processes where the sidewalls of an opening (defined by the thickness of a mask layer) are used to shield physical vapor deposition of layers in the opening. Photolithography processes that typically exhibit low variation can, in some cases, exhibit higher variation when used to make openings with high aspect ratios.

[0043] Reference again Figure 1 In process 100, a feature size associated with a size of a feature is measured (104). For example, in some implementations, the size itself, such as size 206 of opening 204, is measured. For example, size 206 can be a diameter of a circular opening 204, or size 206 can be a side length of a square or rectangular opening 204. In some implementations, multiple feature sizes are measured, such as multiple feature sizes associated with multiple different axes. In some implementations, the feature size is associated with an area of ​​opening 204. For example, the area of ​​opening 204 can be proportional to the size of opening 204. In some examples, in addition to or as an alternative to measuring the feature size, one or more further properties of the feature (such as material composition) can be measured.

[0044] The measured element whose size is associated with the size of the feature (sometimes referred to as a feature) can be an element of the feature itself (e.g., size 206 of opening 204), an element different from the feature and located on the same substrate as the feature, or an element located on a separate substrate. Figure 4As shown, openings 402a, 402b are formed on sample 412. One or more layers will be deposited in openings 402a, 402b, for example, to form at least a portion of a device / junction. In some implementations, dimensions 404a and / or 404b (e.g., side length) of openings 402a, 402b are measured. For example, the area of ​​opening 402a (rectangle) is dimension 404a times dimension 404b. In some implementations, features indicating orthogonal dimensions are measured, for example, dimensions 404a and 404b corresponding to the orthogonal sides of opening 402a. For features oriented in different sizes, feature size changes may be different. For example, the width of the opening may be 10% larger than the target width, while the length of the opening may be 5% larger than the target length. By measuring features oriented in different directions / along different axes, size changes associated with the axis can be detected.

[0045] In some implementations, the measured elements are measured in a lateral direction, for example, in a direction parallel to the surface 208 of the substrate 200 and / or the surface 210 of the initial layer (e.g., the mask layer 202). These lateral dimensions can be associated with the area of ​​the feature, such as the area of ​​the opening 204, and therefore the area of ​​one or more layers subsequently formed in the opening 204. In some implementations, the measured elements are measured in a vertical direction, for example, in a direction perpendicular to the surface 208 of the substrate 200 and / or the surface 210 of the mask layer 202. The vertical non-lateral dimensions can be associated with the thickness of the mask layer 202 and the thickness of one or more layers subsequently formed in the opening 204.

[0046] In some implementations, an element is measured that is different from the feature in the initial layer, but where the size of the element is related to the size of the feature. For example, the size of a different feature can be measured. For example, Figure 4 As shown, the dimensions 404a, 404b of the opening 402a can be measured and, for example, based on the assumption that the variation in the opening dimensions tends to be similar or the same between different openings of the same sample, the dimensions 404a, 404b can indicate the corresponding dimensions of the opening 402b. The dimensions 404a, 404b of the opening 402a can indicate the area of ​​the opening 402b based on the correlation of the dimensions with the corresponding dimensions of the opening 402b. The opening 402b can be formed in the same manufacturing process as the opening 402a (e.g., using common photolithography steps), so that the variation in the dimensions of the openings 402a and 402b can be expected to be similar or the same.

[0047] In some implementations, one or more calibration features can be formed on the same sample as the features in the initial layer. For example, calibration features 406, 408 can be formed on the same sample 412 as openings 402a, 402b. For example, calibration features 406, 408 can be disposed on the same substrate as the mask layer defining openings 402a, 402b. In some implementations, calibration features 406, 408 include openings 402a, 402b and / or are defined by the same mask layer defining openings 402a, 402b. For example, openings 402a, 402b can be openings in a photoresist mask layer, and calibration features 406, 408 can include openings in the photoresist mask layer and / or patterned features of the photoresist mask layer. In some implementations, the calibration features 406, 408 can be formed at least in part in the same manufacturing process as the openings 402a, 402b (e.g., using common photolithography steps), so that the size variation of the openings 402a, 402b can be expected to be similar (e.g., proportional) to the size variation of the calibration features 406a, 406b. For example, a photolithography mask that includes features to define the openings 402a, 402b in the mask layer can also include features to define the calibration features 406, 408 in the mask layer. The calibration features 406, 408 can have any suitable geometry, such as a cross, a ridge, a post, and / or a defined opening (such as a valley / groove).

[0048] In some implementations, one or more dimensions 410a, 410b of the calibration features 406, 408 are measured. For example, one or more widths, lengths, diameters, depths, and / or radii of the calibration features 406, 408 may be measured. Because the calibration features 406, 408 are disposed on the same sample 412 as the openings 402a, 402b, are defined in or by the same mask layer that defines the openings 402a, 402b, and / or are at least partially formed in the same manufacturing process as the openings 402a, 402b, changes in the dimensions 410a, 410b, 410c of the calibration features 406, 408 are associated with changes in the dimensions 404a, 404b of the openings 402a, 402b. For example, in some implementations, changes in the dimensions of the calibration features 406, 408 are proportional to changes in the dimensions of the openings 402a, 402b, such as in the same direction. For example, because dimension 410a is parallel to dimension 404a, dimension 404a may be determined based on a measurement of dimension 410a.

[0049] For example, if dimension 410a has a nominal value (eg, an expected value, a target value, an average value, or other standard value) L 1,a and the measured actual value L 1,a +ΔL 1,a , and dimension 404a has a nominal value L2,a , it can be determined that the dimension 404a has an actual value L 2,a +c a ΔL 1,a , where c a is the proportionality constant. c a The calibration feature 406 may be based on one or more of the following: the relative position of the opening 402a and the calibration feature 406 (e.g., the distance between the opening 402a and the calibration feature 406), the position of the opening 402a and / or the calibration feature 406 on the sample 412 and / or relative to the sample processing system, and / or another parameter. For example, a smaller distance between the opening 402a and the calibration feature 406 may be associated with a c closer to 1. a For a longer distance between the opening 402a and the calibration feature 406, c a can be scaled to be farther from 1 (e.g., positive and closer to 0, or greater than 1). In some implementations, a similar relationship L 2,b +c b ΔL 1,b The actual value of dimension 404b may be provided based on the measurement of dimension 410b or dimension 410c, where c b Can be used with c a The same or different. Based on the inferred or measured actual values ​​of dimensions 404a and 404b, the area of ​​opening 402a may be determined, for example, by multiplying dimensions 404a and 404b or performing another suitable operation.

[0050] The above mathematical relationship is one example. Other ratios, equations, algorithms, and relationships between measured sizes / dimensions and corresponding opening sizes / areas are within the scope of the present disclosure.

[0051] In some implementations, the calibration feature to be measured is disposed on a sample separate from the sample having the feature in the initial layer. Figure 4 As shown, the platen 416 accommodates the sample 412 and a separate sample 414, such as a separate wafer or another substrate. For example, the platen 416 can be a platen of a sample processing system, and the calibration features 418 on the separate sample 414 can be formed at least in part in the same manufacturing process as the openings 402a, 402b. One or more dimensions 420a, 420b of the calibration features 418 can be measured, based on which the size of the openings 402a, 402b (associated with the area of ​​the openings 402a, 402b) can be determined. For example, one or more of the dimensions 420a, 420b can be related to the size of the openings 402a, 402b according to a predetermined relationship.

[0052] In some implementations, it may be advantageous to measure a separate calibration feature rather than or in addition to the measurement feature itself. For example, a separate calibration feature may have a structure (e.g., shape and / or size) configured for accurate and efficient measurement, whereas the structure of the feature (e.g., opening) may be configured based on the properties of a device manufactured using the feature, which may result in less accurate measurements. Additionally, in some implementations, the measurement may introduce contamination into the measured feature, resulting in distortion or damage to the measured feature, etc., which may change the properties of a device manufactured using features such as openings. By measuring the calibration feature, the feature used for device manufacturing may remain in a pristine state.

[0053] Any suitable measurement technique or combination of techniques may be used for measurement. In some implementations, the measurement includes an optical microscope, such as a confocal microscope. In some implementations, the measurement includes a non-optical microscope, such as an electron microscope (e.g., a scanning electron microscope or a tunneling electron microscope). In some implementations, the measurement includes a physical measurement, such as an atomic force microscope or a profilometry method. In some implementations, the measurement has a spatial resolution of 1 nm, 5 nm, or another value less than 10 nm, which is provided by some implementations of the atomic force microscope. In some implementations, the atomic force microscope can effectively measure the size of the narrow opening in the mask layer 202 because the atomic force microscope tip is small enough to fit into a narrow opening that can be about 100 nm wide. In some implementations, the measurement is performed in situ, for example, in a chamber (such as a physical vapor deposition chamber and / or an oxidation chamber) where the first layer is formed and / or the second layer is formed.

[0054] Reference again Figure 1 , based on the one or more measured feature sizes, determining one or more manufacturing parameters (106). For example, a stored relationship (e.g., an algorithm or machine learning model) may relate the one or more manufacturing parameters to the one or more measured feature sizes. The relationship may be stored in a memory of the computing system.

[0055] The manufacturing parameters are adjustable parameters (108) of the manufacturing process performed based on the manufacturing parameters (i.e., the manner in which the manufacturing process is performed may vary depending on the value of the manufacturing parameters). For example, one or more layers may be formed based on the manufacturing parameters, one or more features may be formed based on the manufacturing parameters, one or more subtractive processes such as etching may be performed based on the manufacturing parameters, and / or one or more modified manufacturing processes may be performed based on the manufacturing parameters. Figure 2BAs shown, in some implementations, the second layer 212 is formed in the opening 204 based on manufacturing parameters. For example, when the second layer 212 is deposited by physical vapor deposition (e.g., thermal evaporation or sputtering), the manufacturing parameters can be a deposition duration and / or a deposition rate, which together determine the thickness 214 of the second layer 212. Other examples of manufacturing parameters include temperature (e.g., the temperature of the substrate 200 or the chamber temperature during the formation of the second layer 212), pressure (e.g., the chamber pressure during the formation of the second layer 212), a gas mixture associated with forming the second layer 212 (e.g., the relative proportions of different gases such as a precursor gas and an oxidant gas), and / or a spin rate. The second layer 212 can be formed by physical vapor deposition, chemical deposition (e.g., chemical vapor deposition, such as plasma enhanced chemical vapor deposition or atomic layer deposition), spin deposition, or another suitable layer formation process.

[0056] In some implementations, one or more features can be formed based on manufacturing parameters. Features can include, for example, ridges, grooves, bumps, protrusions, pads, and / or cylinders (eg, in an array of cylinders).

[0057] The manufacturing parameters need not be associated with additive manufacturing such as layer formation. For example, in some implementations, the manufacturing parameters may be associated with subtractive manufacturing operations and / or modified manufacturing operations. Subtractive manufacturing may include, for example, etching or lithography (lithography may include an etching process). For example, instead of depositing the second layer 212 in the opening 204 or in addition to depositing the second layer 212 in the opening 204, a process may be performed to etch the substrate 200 in the opening 204, for example, to increase the depth of the opening 204 or to form an etched feature (e.g., a groove) in the opening 204. Processing may be performed alternatively or additionally to remove or pattern the initial layer, for example, to form further features in the initial layer. The manufacturing parameters of the subtractive process may include, for example, lithography parameters (e.g., exposure dose or development chemistry / time, resist type and deposition parameters, selection of the geometry of the patterned features, etc.) and / or etching parameters (e.g., etchant chemistry such as a gas composition for plasma etching or a liquid composition for wet chemical etching, etching duration, or other etching parameters such as power for plasma etching). For example, an opening can be formed in the initial layer, wherein one or more sizes / shapes of the opening, and / or one or more parameters for forming the opening are determined based on the measured feature size. The modification manufacturing operation can include, for example, oxidation, annealing, or chemical treatment (e.g., by exposure to a gas or liquid). The manufacturing parameters of the modification manufacturing operation can include, for example, temperature, duration (e.g., time for annealing the sample), and / or the chemical composition (e.g., gas mixture or liquid solution) to which the sample (e.g., the initial layer) is exposed.

[0058] The manufacturing parameters may be determined such that the manufacturing parameters, in combination with one or more dimensions of features associated with the measured feature size, cause one or more formed layers, devices, or structures to have one or more target properties. For example, the manufacturing parameters may cause one or more structures (which may include one or more additional layers formed based on the manufacturing parameters, one or more structures formed in an initial layer and / or substrate based on the manufacturing parameters, and / or one or more structures modified based on the manufacturing parameters) to have desired morphological, chemical, electrical, and / or optical properties.

[0059] For example, the manufacturing parameters may cause the second layer formed in the opening of the mask layer to have one or more target properties and / or cause a device including the second layer to have one or more target properties. For example, the manufacturing parameters may be selected so that the second layer 212 has a target thickness 214, a target density, a target composition, a target optical property (e.g., a target refractive index), a target electrical property (e.g., a target conductivity), and / or another target parameter.

[0060] In with Figure 2B In a related example, the second layer 212 may be a resistive layer of a resistor having a resistance of R-ρt / A, where ρ is the resistivity of the second layer 212, t is the thickness 214 of the second layer, and A is the cross-sectional area of ​​the second layer 212, which is defined by the area of ​​the opening 204 (e.g., at least partially determined by the dimension 206 of the opening 204). The target resistance of the resistor is R0. Therefore, when A is determined by measuring the dimension 206 and / or measuring the size of one or more other features, the manufacturing parameters (e.g., deposition duration) used to form the second layer 212 may be selected so that the thickness 214 is R0×A / ρ, thereby achieving the target resistance R0. In some implementations, the manufacturing parameter determination is performed based on a change from the target value. For example, the target resistance R0 may be associated with a target thickness t0 and a target area A0. In response to determining that the actual area is 1.1A0 (corresponding to a 10% deviation in the manufacturing area), one or more manufacturing parameters may be selected so that the thickness 214 formed is 1.1ι0, thereby achieving the target resistance. As another example related to resistance, instead of or in addition to selecting manufacturing parameters to set thickness 214, manufacturing parameters (e.g., deposition rate or substrate temperature during deposition, such as to control the crystallinity of second layer 212) can be selected to set a resistivity p that provides a target resistance. In general, variations in feature size can be compensated for by employing appropriate manufacturing parameters so that target characteristics can be reliably achieved.

[0061] The second layer 212 may be composed of any material or combination of materials that provide desired properties or functions for the second layer 212 and / or a device including the second layer 212. For example, the second layer 212 may be a metal layer, a dielectric layer (such as an oxide layer or a nitride layer), a semiconductor layer, and / or an organic layer.

[0062] Figure 2C An example of forming two layers in the opening 204 is shown. A first layer 216 is formed on the substrate 200, and a second layer 218 is formed on the first layer 216. The manufacturing parameters for forming one or both of the first layer 216 and the second layer 218 can be determined based on the feature size. For example, in some implementations, the manufacturing parameters for setting the thickness 220 of the second layer 218 are determined based on the feature size. The first layer 216 and the second layer 218 can be composed of any combination of material types as described above for the second layer 212. In some implementations, the area of ​​the first layer 216 and / or the second layer 218 is set by the area of ​​the opening 204 (e.g., equal to the area of ​​the opening 204 or having a predetermined relationship with the area of ​​the opening 204).

[0063] Figure 3A An example of forming an oxide layer on the first layer 216 as the second layer 218 is shown. In this example, the second layer 218 is an oxide formed by oxidizing a portion of the first layer 216, such that the second layer 218 is formed on the remaining portion of the first layer 216. To oxidize the first layer 216, an oxidizing gas 300 (such as oxygen, ozone, hydrogen peroxide, and / or water vapor) is provided to a sample chamber containing the substrate 200 and the layers thereon. For example, the oxidizing gas 300 can be provided at a partial pressure P for an exposure time t, where P and t are proportional as the thickness 220 of the second layer 218 increases. In some implementations, the substrate 200 is heated to a predetermined temperature range during exposure to the oxidizing gas 300. In some implementations, the one or more manufacturing parameters determined based on the feature size include one or more of the following: a partial pressure P of the oxidizing gas 300, an exposure time t, a composition of the oxidizing gas 300 (e.g., selecting a single gas, or relative concentrations of multiple gases), a total pressure during oxidation (not a partial pressure), or another parameter such as a temperature of the substrate 200 during oxidation. Configuration of these and / or other manufacturing parameters may determine the thickness of the oxide formed on the first layer 216 .

[0064] In some implementations, the first layer 216 is a metal and the second layer 218 is a metal oxide of the metal. For example, the first layer 216 may be aluminum and the second layer 218 may be aluminum oxide. As another example, the first layer 216 may be niobium and the second layer 218 may be niobium oxide. As another example, the first layer 216 may be tantalum and the second layer 218 may be tantalum oxide. In some implementations, the first layer 216 is a metal that exhibits superconductivity at low temperatures, such as with respect to Figure 2D In some implementations, the exposure time t is of the order of a few minutes or tens of minutes, such as between ten minutes and one hour. In some implementations, the partial pressure P is of the order of tens of millitorr, such as between 10 millitorr and 100 millitorr. Other suitable pressures and exposure times are also within the scope of the present disclosure.

[0065] Figure 3B Another example of forming an oxide layer on the first layer 216 as the second layer 218 is shown. In this example, the second layer 218 is formed by physical and / or chemical deposition. For example, atomic layer deposition (ALD) or sputtering can be used to deposit the oxide layer as the second layer 218. In the case of a chemical deposition process, a precursor gas 302 for the second layer 218 is provided to the sample chamber, such as an organic metal compound (e.g., trimethylaluminum). In the case of a physical vapor deposition process, vapor 302 (projected source material) is present in the sample chamber, and in some implementations, an oxidizing gas is also present. Manufacturing parameters that can be determined based on the feature size include deposition time T, deposition rate r (e.g., related to sputtering power or thermal evaporation heating power), gas composition (e.g., for chemical vapor deposition or sputtering oxidation), gas pressure, or another parameter such as the temperature of the substrate 200 during deposition of the second layer 218.

[0066] In some implementations where the second layer 218 is formed on the first layer 216, the third layer is formed on the second layer 218. Figure 2D As shown, the third layer 222 is formed on the second layer 222. When the third layer 222 is included, the first layer 216, the second layer 218, and the third layer 222 can be composed of any combination of material types as described above for the second layer 212. In some implementations, the third layer 222 is composed of the same material or combination of materials as the first layer 216. In some implementations, the area of ​​the third layer 222 is set by the area of ​​the opening 204 (for example, equal to the area of ​​the opening 204 or has a predetermined relationship with the area of ​​the opening 204). The third layer 222 can be formed by any suitable manufacturing method, including oxidation, physical vapor deposition, and / or chemical deposition of the second layer 218. In some implementations, one or more manufacturing parameters for forming the third layer 222 are determined based on one or more measured feature sizes.

[0067] In some implementations, the second layer 218 is a thin insulating layer (eg, a dielectric layer), such as an oxide layer or a nitride layer, and the first layer 216 and the third layer 222 are made of a superconducting layer having a critical temperature T C One or more materials such that when the layer temperature drops below T C When the first layer 216, the second layer 218 and the third layer 222 form a Josephson junction 224. A material having superconductivity at low temperatures may be referred to as a "superconductor material". In some implementations, the first layer 216 is a superconductor metal; the second layer 218 is an oxide layer formed by oxidizing a portion of the first layer 216, as shown in FIG. Figure 3A As described, the second layer 218 is an oxide of a superconductor metal; and the third layer 222 is another superconductor metal, such as the superconductor metal of the first layer 216. For example, the first layer 216 and the third layer 222 can be composed of aluminum, and the second layer 218 can be composed of aluminum oxide. As another example, the first layer 216 can be composed of aluminum, the second layer 218 can be composed of aluminum oxide (e.g., grown aluminum oxide), and the third layer 222 can be composed of a superconductor material other than aluminum. As another example, the first layer 216 and the third layer 222 can be composed of niobium, and the second layer 218 can be composed of niobium oxide. As another example, the first layer 216 and the third layer 222 can be composed of tantalum, and the second layer 218 can be composed of tantalum oxide.

[0068] Other materials and combinations of Josephson junction materials are also within the scope of the present disclosure. For example, some implementations of the first layer 216, the second layer 218, and the third layer 222 that form the Josephson junction are different from the metal-oxide-metal structure. For example, in some implementations, the second layer 218 is a nitride (e.g., silicon nitride) or a semiconductor (e.g., InAs).

[0069] For the sake of clarity, FIG. 2B to FIG. 2D The layers 212, 216, 218, and 222 are shown in the opening 204 and not elsewhere. However, in some cases, the layers 212 can be formed elsewhere in addition to the opening 204. For example, the physical vapor deposition process can cause the first layer 216 to be deposited not only in the opening 204, but also on the mask layer 202. In some implementations, a stripping or etching process can be used to remove other portions of the layers 212, 216, 218, and 222. For example, at least a portion of the mask layer 202 can be removed to strip portions of the layers 212, 216, 218, and 222 formed on the mask layer 202.

[0070] In some implementations where the first layer 216, the second layer 218, and the third layer 222 form a Josephson junction, one or more manufacturing parameters are determined to set one or more parameters of the Josephson junction and / or a device including the Josephson junction to a target value. When the first layer 216 and the third layer 222 are composed of the same superconductor material (e.g., aluminum metal), the critical current of the Josephson junction is where Δ is the superconducting gap energy, and R n is the normal state resistance of the Josephson junction. R n The relationship with the parameter of the second layer 218 is R n ∝t / A, where t is the thickness 220 of the second layer 218 and A is the junction area, which is set by the area of ​​the opening 204 and is therefore related to the lateral dimensions of the opening 204 and any calibration features.

[0071] For transport sub-qubits including Josephson junctions (about Figure 6B discussed in more detail), the fundamental transition (resonant) frequency where C is the qubit capacitance, and E C is the qubit charge energy L is the Josephson inductance Where Φ0 is the magnetic flux quantum Therefore, R n The change of f 01 to I C In some cases, R n The change is f 01 The main source of variation. 01 itself can be an important parameter in qubit design and operation. n The change can be more reliably provided by f 01 The target value of f is used to improve the performance of qubits. 01 Changes in the qubit state or other qubit parameters may result in undesired qubit state transitions, qubit state leakage, and / or other effects associated with poor qubit performance.

[0072] To obtain this improved qubit reliability, in some implementations, one or more fabrication parameters are determined to form second layer 218 so as to provide a target value for a qubit parameter of a qubit comprising a Josephson junction formed by first layer 216, second layer 218, and third layer 222. For example, the qubit may be a transport qubit, and the target value may be a qubit parameter R π ,I C , L or f 01 In some implementations, the target value may be the qubit parameter E C(charge energy) or E J Based on the measured feature size, the manufacturing parameters for forming the second layer 218 are determined to achieve the target R n ,I C , L or f 01 For example, when the measured feature size is smaller than the target value (indicating that the opening 204 is too wide due to manufacturing variations), A is also smaller than the target value, and thus, the exposure time for forming the second layer 218 may be reduced from the standard value to form a thinner second layer 218 (smaller value of t) such that R n ∝t / A is maintained at a target value, which provides f 01 The exposure time may be determined based on a stored relationship between the measured feature size and the corresponding exposure time.

[0073] In some implementations, a feed-forward process that modifies manufacturing parameters for subsequent processing (e.g., forming one or more of first layer 216, second layer 218, and third layer 222) may be more efficient than a process that modifies an already formed structure ("post-manufacturing processing") to achieve a target parameter value (e.g., a target qubit parameter). First, post-manufacturing processing may be associated with increased cost, process complexity, and / or sample contamination compared to some implementations described herein because post-manufacturing processing introduces one or more additional steps. In contrast, some implementations of the feed-forward process described herein modify manufacturing parameters of existing manufacturing steps without adding additional steps, thereby maintaining overall process efficiency. In addition, some post-manufacturing processing may be limited to modifying the structure so that the parameter value is shifted in only one direction. For example, if the f of a qubit is 01 If f is lower than the target value, one or more of the already formed layers of the qubit can be modified so that f 01 is set to the target value; however, if f 01 Above the target value, post-fabrication processing to reduce the frequency may not be feasible given the available methods. In contrast, some feed-forward processing implementations of the present disclosure, such as exposure time modification for oxidation to form the second layer 218, can adjust parameter values ​​up or down to increase flexibility in reducing parameter variation.

[0074] FIG. 5A to FIG. 5C An example of a dual angle deposition process is shown, which can be used to make junctions such as Josephson junctions. Figure 5A As shown, an opening 500 is defined in a photoresist mask layer 502. The opening 500 includes two intersecting portions: a first opening portion 506a and a second opening portion 506. The opening 500 may be defined in the photoresist mask layer 502 by photolithography or electron beam lithography.

[0075] The first opening portion 506 has a width 508. In the measurement process, the width 508 is measured directly, and / or the width of a calibration feature is measured, where the width of the calibration feature is indicative of the width 508. For example, the probe of an atomic force microscope can be scanned along line 510 to determine the width 508, and / or the probe can be scanned over the calibration feature along a line parallel to line 510 to obtain a feature size from which the width 508 is inferred. In some implementations, the width 512 of the second opening portion 506b can be determined using a similar process (e.g., directly measuring the width 512 and / or measuring the corresponding size of the calibration feature). In some implementations, the width 512 is determined based on the same measurement as the width 508, for example, the change in the width 512 from the nominal value can be determined to be the same or proportional to the change in the width 508 relative to the nominal value.

[0076] In some implementations, the opening 500 is cleaned before and / or after the measurement. For example, a plasma cleaning process (e.g., a "de-slag" oxygen plasma clean) can be performed before and / or after the measurement. When cleaning is performed after the measurement, in some implementations, the cleaning can at least partially remove contamination associated with the measurement.

[0077] like Figure 5B As shown, a first layer 514 (e.g., first layer 216) is deposited in opening 500 by physical vapor deposition at a first deposition angle indicated by deposition direction 504. Due to the aspect ratio of opening 500 (e.g., due to the high ratio of the height of the photoresist sidewalls of opening 500 to width 512), first layer 514 is deposited in first opening portion 506a, but not in second opening portion 506b (except for the intersection of the two opening portions 506a, 506b). For example, first layer 514 can be a metallic superconductor material, such as aluminum or niobium.

[0078] like Figure 5C As shown, the first layer 514 is exposed to an oxidizing gas composition 518, such as oxygen, to oxidize the upper portion of the first layer 514 and form a second layer 516 (e.g., second layer 118). For example, the second layer 516 can be aluminum oxide or niobium oxide. One or more oxide growth parameters are determined based on the measured / determined widths 508, 512 to set the thickness of the second layer 516. For example, the pressure of one or more gases in the oxidizing gas composition 518, the duration of exposure to the oxidizing gas composition 518, and / or the temperature of the fabricated sample during oxidation can be controlled to set the thickness of the second layer. The thickness is set so that the Josephson junction including the first layer 514 and the second layer 516 has a thickness such as R n ,I C , L and / or f 01 The target value for one or more parameters.

[0079] In some implementations, the thickness may be very thin, such as on the order of nanometers, such that the thickness may not be uniform across the second layer 516 and may not be clearly defined as a single value. However, by adjusting one or more oxide growth parameters, the average or total thickness may be adjusted to provide a target value. For example, an experimentally derived curve may provide a plot of one or more oxide growth parameters versus R n ,I C , L and / or f 01 For example, the thickness may be adjusted based on the selection of oxide growth parameters without the need to precisely know or consider the thickness when determining the oxide growth parameters.

[0080] Instead of or in addition to forming the second layer 516 by oxidizing the first layer 514, in some implementations, the second layer 516 can be formed by another method such as atomic layer deposition. The second layer 516 need not be an oxide, but can be a nitride, a semiconductor, or another non-superconductor material suitable for forming a Josephson junction.

[0081] like Figure 5D As shown, a third layer 522 (e.g., third layer 222) is deposited in the opening 500 by physical vapor deposition at a second deposition angle different from the first deposition angle indicated by the deposition direction 520. Due to the aspect ratio of the opening 500 (e.g., due to the high ratio of the height of the photoresist sidewalls of the opening 500 to the width 508), the third layer 522 is deposited in the second opening portion 506b instead of in the first opening portion 506a (except for the intersection of the two opening portions 506a, 506b). For example, the third layer 522 can be a metallic superconductor material such as aluminum, niobium, or tantalum. In some implementations, the third layer 522 is composed of the same material as the first layer 514, such as aluminum metal.

[0082] The overlapping region 524 of the first layer 514 and the third layer 522 is a Josephson junction (eg, a superconductor / non-superconductor / superconductor junction when cooled to an appropriate temperature). The overlapping region 524 has an area A, which is the junction area discussed above, and has a value a1 and a2 are coefficients that reflect the fact that the material of the first layer 514 and / or the third layer 522 may not be deposited over the entire width of the opening portions 506a, 506; in some implementations, a1 and / or a2 are equal to 1. The area of ​​the overlap region 524 itself is related to the area of ​​the opening 500 based on their related geometries. Therefore, based on the measured or determined widths 508, 512, A can be determined, and the corresponding Josephson junction t of the second layer 516 can be set by appropriately selecting one or more oxide growth parameters to provide Rn ,I C , L and / or f 01 or another Josephson junction and / or qubit parameter.

[0083] In some implementations, one or more further processing steps are performed after depositing the third layer 522. For example, a stripping step such as immersion in a suitable solvent (e.g., acetone) can be performed to remove the photoresist mask layer 502 and remove the material deposited on the photoresist mask layer 502 during the deposition of the first layer 514 and the third layer 522 together with the photoresist mask layer 502. In some implementations, further processing is performed to couple the first layer 514 and the third layer 522 to corresponding traces / contacts, thereby coupling the Josephson junction to one or more other components of the circuit. For example, the further processing can include photolithography and / or electron beam lithography to fabricate the traces / contacts.

[0084] For example, a Josephson junction fabricated in accordance with implementations of the present disclosure (with one or more fabrication parameters determined based on measured feature sizes associated with the area of ​​the opening) may be integrated into a qubit. FIG. 6A to FIG. 6D The various qubit types that can be integrated into a Josephson junction are shown. Fig. 6A As shown, an example of a charge qubit 600 includes a charge qubit having a Josephson energy E J and capacitor C J The Josephson junction 602 is coupled to a gate capacitor 604 (C g ), and coupled to a voltage source 608 (V g ). This qubit and components of other described qubits can be coupled to each other via conductive or superconducting traces 606.

[0085] like Figure 6B As shown, an example of a transmission sub-qubit 610 includes two Josephson junctions 612 (with corresponding Josephson energies and capacitances), a gate capacitor 614, a voltage source 618, and a shunt capacitor 616 (C B ). The shunt capacitor 616 is configured to make the Josephson energy E J The ratio to the charge energy of the transporter qubit 610 is small, reducing sensitivity to charge noise while maintaining sufficient anharmonicity for selective qubit control. Other transporter configurations (e.g., single Josephson junction transporter configurations and / or configurations without voltage sources) are also within the scope of the present disclosure.

[0086] like Figure 6CAs shown, an example of a flux qubit 620 includes a Josephson junction 622 (eg, as described for Josephson junction 602) and an inductor 624. An external magnetic flux 626 is applied through a loop 628 of the flux qubit 620.

[0087] like Fig.6D As shown, an example of a phase qubit 630 includes a Josephson junction 632 (eg, as described with respect to Josephson junction 602 ) and a current source 634 .

[0088] Implementations of the present disclosure can be used to fabricate qubits having these and other circuit topologies / configurations such that the qubit and / or one or more Josephson junctions of the qubit have one or more target parameters, such as R n ,I C , L, charge energy E C 、Josephson energy E J and / or f 01 In some implementations, one or more of these and / or other target parameters are achieved by selecting oxide growth parameters for an oxide layer of a Josephson junction based on the measured feature size. Thus, qubit operation may be improved by providing qubits with more stable parameters across different fabrication iterations.

[0089] FIG. 6A to FIG. 6D The qubits shown in are examples; qubits within the scope of the present disclosure may have other configurations, such as fewer components or additional components (e.g., more Josephson junctions than shown).

[0090] For Josephson junction implementations, a feed-forward process that modifies oxide growth parameters for forming the second layer 218 (oxide) based on measurements of feature sizes associated with the size of the opening may be advantageous over other methods that may reduce Josephson junction parameter variations. As described above, the variation in oxide parameters for each sample does not require post-manufacturing processing of the sample, but rather represents a modification to an existing portion of the manufacturing process. In addition, while some implementations described herein include a measurement process, the measurement process is performed prior to forming the oxide layer of the Josephson junction, such that contamination associated with the measurement process may be reduced, for example, by post-measurement cleaning and / or because the measurement process does not directly affect the metal oxide interface because the interface has not yet formed at the time of measurement. In contrast, some processes based on post-manufacturing measurements (e.g., post-manufacturing electrical measurements) may introduce contamination into manufactured devices, thereby compromising device performance.

[0091] Furthermore, for some implementations according to the present disclosure, it has been recognized that (i) variations in the size of the opening (associated with the final Josephson junction area) can be a significant source of variation in Josephson junction parameters, (ii) measurements of feature sizes associated with the opening area can be made during the Josephson junction fabrication process, and (iii) oxide growth parameters can vary based on the measured feature sizes. Based at least on a combination of these elements, Josephson junction parameters can be more reliably located, thereby improving qubit performance.

[0092] Figure 7 An example of a system 700 in which some processes according to the present disclosure may be implemented is shown. The system 700 includes a control system 702, such as a computer system including one or more computers. The control system 702 may be local to the other components of the system 700 and / or at least partially remote, such as a cloud-based or server-based control system. The control system 702 is communicatively coupled to a deposition system 704, an oxidation system 706, a measurement system 708, a lithography system 710, and an etching system 712.

[0093] The lithography system 710 may include one or more lithography tools / devices, such as a lithography tool, an electron beam lithography tool, a resist deposition tool, a resist development tool, and / or a resist exposure tool. The lithography system 710 may be configured to form openings in the mask layer and / or calibration features in the mask layer, such as by depositing a resist onto a substrate, exposing the resist to a pattern corresponding to the openings and / or calibration features, and developing the resist. In some implementations, the lithography system 710 may be configured to form one or more additional features (e.g., in the mask layer) according to one or more manufacturing parameters determined based on the measured feature size. The control system 702 may be configured to cause the lithography system 710 to form features in the initial layer (e.g., openings, pads, ridges, feature arrays, etc. in the mask layer), calibration features, and / or one or more additional features, for example, by providing appropriate commands to the lithography system 710.

[0094] The etching system 712 may include one or more material removal tools / devices, such as wet chemical etching tools and / or plasma etching tools. The etching system 712 may be configured to form features in the initial layer, calibration features, and / or one or more additional features according to one or more manufacturing parameters determined based on the measured feature size. The control system 702 may be configured to cause the etching system 712 to form a material removal process, for example, by providing appropriate commands to the etching system 712.

[0095] The measurement system 708 may include one or more measurement devices as described above, such as an optical microscope, an electron microscope, and / or an atomic force microscope. The control system 702 is configured to cause the measurement system 708 to measure a feature size associated with the opening in the mask layer, for example, by providing appropriate commands to the measurement system 708. The control system 702 is configured to receive measurement results from the measurement system 708 and determine one or more manufacturing parameters based on the measurement results.

[0096] The deposition system 704 includes one or more manufacturing tools configured to form at least one of the first, second, or third layers 212, 216, 218, 222. For example, the deposition system 704 may include a chemical vapor deposition tool (e.g., a chamber having a gas inlet and connected to a pump) and / or a physical vapor deposition tool (e.g., a thermal evaporator, an electron beam evaporator, or a sputterer). For example, the control system 702 may be configured to cause the deposition system 704 to form at least one of the first, second, or third layers 212, 216, 218, 222, for example, by providing appropriate commands to the deposition system 704. The layers and features formed by the deposition system 704 may be formed using one or more manufacturing parameters determined based on the measured feature size.

[0097] In some implementations where at least one layer (e.g., second layer 218) is an oxide, system 700 includes an oxidation system 706 configured to form the oxide. Oxidation system 706 may include an oxidation chamber and an associated gas management device for providing an oxidizing gas into the oxidation chamber. In some implementations, the oxidation chamber is a chamber in which one or more deposition processes are performed. For example, deposition system 704 and oxidation system 706 may share a common chamber in which physical vapor deposition and oxidation are performed; after depositing a first layer, an oxidizing gas may be provided to the chamber to oxidize the first layer (forming a second layer), and then a third layer may be deposited on the second layer in the chamber. Control system 702 is configured to cause oxidation system 706 to form an oxide layer, for example, by providing appropriate commands to oxidation system 706.

[0098] Some of the features described may be implemented in digital and / or analog electronic circuitry or in computer hardware, firmware, software, or a combination thereof, such as control system 702. Some of the features may be implemented in a computer program product tangibly embodied in an information carrier, such as in a machine-readable storage device (e.g., included in control system 702), for execution by a programmable processor. Method steps may be performed by a programmable processor (e.g., included in control system 702) executing a program of instructions to perform the functions of the described implementation by operating on input data and generating output, by discrete circuitry (e.g., included in control system 702) performing analog and / or digital circuit operations, or by a combination thereof.

[0099] Some of the described features may advantageously be implemented in one or more computer programs that can be executed on a programmable system that includes at least one programmable processor coupled to receive data and instructions from and send data and instructions to a data storage system, at least one input device, and at least one output device. A computer program is a set of instructions that can be used directly or indirectly in a computer to perform some activity or produce some result. A computer program can be written in any form of programming language (e.g., Objective-C, Java), including compiled or interpreted languages, and the computer program can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0100] Suitable processors for executing instruction programs include, for example, both general-purpose microprocessors and special-purpose microprocessors, as well as the sole processor of any kind of computer, or one of multiple processors or cores. Typically, the processor will receive instructions and data from a read-only memory or a random access memory or both. The basic elements of a computer are a processor for executing instructions and one or more memories for storing instructions and data. In general, a computer can communicate with a mass storage device to store data files. These mass storage devices may include disks, such as built-in hard disks and removable disks; magneto-optical disks; and optical disks. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including, for example, semiconductor memory devices (such as EPROM, EEPROM, and flash memory devices); disks (such as built-in hard disks or removable disks); magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and memory may be supplemented by or incorporated into an ASIC (Application Specific Integrated Circuit). To provide for interaction with a user, the features may be implemented on a computer having a display device such as a CRT (cathode ray tube), LED (light emitting diode), or LCD (liquid crystal display) display or monitor for displaying information to the author, a keyboard through which the author can provide input to the computer, and a pointing device such as a mouse or trackball.

[0101] A variety of implementations have been described. However, it should be understood that various modifications may be made. Elements of one or more implementations may be combined, deleted, modified, or supplemented to form further implementations. In yet another example, the logic flow depicted in the figure does not require the particular order or sequential order shown to achieve the desired results. In addition, other steps may be provided, or steps may be deleted from the described flow, and other components may be added to or removed from the described system. Therefore, other implementations are within the scope of the following claims.

Claims

1. A method comprising: forming an opening in the mask layer; measuring a feature size associated with a size of the opening; determining manufacturing parameters based on the feature size; as well as A second layer is formed in the opening, wherein forming the second layer is based on the manufacturing parameters.

2. The method of claim 1, wherein the second layer comprises an oxide layer, and The manufacturing parameters include oxide growth parameters.

3. The method of claim 2, wherein forming the second layer comprises: forming a first layer in the opening; as well as The oxide layer is formed on the first layer. 4 . The method of claim 3 , wherein forming the second layer comprises growing the oxide layer by oxidizing the first layer based on the oxide growth parameters.

5. A method as claimed in claim 3 or claim 4, wherein the first layer comprises a metal, and wherein the method comprises: After forming the oxide layer, a third layer is formed on the oxide layer to form a Josephson junction.

6. The method of claim 5, comprising forming a qubit comprising the Josephson junction.

7. The method of claim 5 or claim 6, wherein forming the first layer comprises depositing the first layer at a first deposition angle, and Wherein forming the third layer comprises depositing the third layer at a second deposition angle different from the first deposition angle.

8. A method as claimed in any one of claims 5 to 7, wherein the metal comprises a superconductor material.

9. The method of any one of claims 2 to 8, wherein forming the second layer comprises exposing the first layer or the first layer to an oxidizing gas at a partial pressure for a period of time, and Wherein the oxide growth parameters include the partial pressure.

10. The method of any one of claims 2 to 9, wherein forming the second layer comprises exposing the first layer or the first layer to an oxidizing gas at a partial pressure for a period of time, and Wherein the oxide growth parameters include the period of time.

11. The method of any one of the preceding claims, further comprising: forming a circuit element including the second layer and a first layer on which the second layer is disposed, wherein determining the manufacturing parameters includes: obtaining a target resonant frequency of the circuit element or a target critical current of the circuit element; determining a junction area based on the measured feature size; and The value of the manufacturing parameter is determined based on the junction area, and when the manufacturing parameter is applied during the formation of the second layer, the circuit element exhibits the target resonant frequency or the target critical current.

12. The method of claim 11, wherein determining the manufacturing parameters comprises: obtaining a target thickness of the second layer that enables the circuit element to have the target resonant frequency or the target critical current; as well as A value of the manufacturing parameter that causes the second layer to have the target thickness is determined.

13. The method of any one of the preceding claims, wherein measuring the feature size comprises measuring the dimension of the opening.

14. The method of any of the preceding claims, wherein measuring the feature size comprises measuring a dimension of a calibration structure defined by the mask layer, wherein the calibration structure is distinct from the opening.

15. The method of any one of the preceding claims, wherein determining the manufacturing parameters comprises: determining that the feature size is greater than a predetermined feature size, and In response to determining that the feature size is greater than the predetermined feature size, selecting the manufacturing parameters to cause a thickness of the second layer to be thicker than a first thickness associated with the predetermined feature size; or determining that the feature size is less than the predetermined feature size, and In response to determining that the feature size is less than the predetermined feature size, the manufacturing parameters are selected such that the thickness of the second layer is thinner than the first thickness associated with the predetermined feature size.

16. The method of any of the preceding claims, wherein measuring the feature size comprises measuring the feature size using an atomic force microscope.

17. A manufacturing system comprising: Lithography systems; Measurement systems; Physical vapor deposition system; Oxidation system; and A control system, wherein the control system is configured to perform operations comprising: causing the photolithography system to form an opening in the mask layer; causing the measurement system to measure a feature size associated with a size of the opening; determining oxide growth parameters based on the feature size; causing the physical vapor deposition system to deposit a first metal layer in the opening; causing the oxidation system to oxidize a portion of the first metal layer based on the oxide growth parameters to form an oxide layer on the first metal layer; and The physical vapor deposition system is caused to deposit a second metal layer on the oxide layer.

18. The manufacturing system of claim 17, wherein causing the oxidation system to oxidize the portion of the first metal layer comprises causing the oxidation system to expose the first metal layer to an oxidizing gas for a period of time, and Wherein the oxide growth parameters include the period of time.

19. The manufacturing system of claim 17 or claim 18, wherein the first metal layer, the oxide layer, and the second metal layer form a Josephson junction below a critical temperature, and wherein the operation comprises: obtaining a target resonant frequency of a qubit including the Josephson junction or a target critical current of the Josephson junction; determining a junction area element based on the measured feature size; as well as A value of the oxide growth parameter is determined based on the junction area, which, when applied during the formation of the oxide layer, causes the qubit to exhibit the target resonant frequency or causes the Josephson junction to exhibit the target critical current.

20. The manufacturing system of any one of claims 17 to 19, wherein measuring the feature size comprises: measuring the dimensions of the opening, or A dimension of a calibration structure defined by the mask layer is measured, wherein the calibration structure is distinct from the opening.

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