CN109607474B - Superconducting vacuum bridge and preparation method thereof - Google Patents
Superconducting vacuum bridge and preparation method thereof Download PDFInfo
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- CN109607474B CN109607474B CN201910070966.5A CN201910070966A CN109607474B CN 109607474 B CN109607474 B CN 109607474B CN 201910070966 A CN201910070966 A CN 201910070966A CN 109607474 B CN109607474 B CN 109607474B
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- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
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Abstract
The invention discloses a superconducting vacuum bridge and a preparation method thereof, wherein the preparation method comprises the following steps: spin-coating an LOR material on a substrate to serve as an LOR sacrificial layer; spin-coating a first photoresist on the LOR sacrificial layer, and performing mask exposure, wherein the mask exposure defines the position of the bridge pier; carrying out first development to obtain three-dimensional structures of a pier and a bridge arch; removing unexposed photoresist on the bridge arch by utilizing the solubility difference between the first photoresist and the LOR material in acetone; heating and refluxing the LOR material at the bridge arch at a set temperature to obtain an edge rounded bridge arch; sequentially spin-coating an LOR layer and a second photoresist on the edge arched arch bridge; exposing the second photoresist and carrying out second development; evaporating a superconducting metal layer; and releasing the LOR sacrificial layer below the bridge arch of the superconducting metal layer and the structure at the position of the non-superconducting bridge to obtain the superconducting vacuum bridge. The method does not need the process of flood exposure and photoresist removal by adopting developing solution, has simple process and can prepare the superconductive vacuum bridge with the diameter of more than 10 microns.
Description
Technical Field
The disclosure belongs to the technical field of preparation and application of micron superconducting circuits, and relates to a superconducting vacuum bridge and a preparation method thereof.
Background
An air bridge is a circuit structure that is a way to implement the crossover of a planar circuit in a three-dimensional bridge fashion. The operating frequency range of the line can be extended due to the use of air as a dielectric between the two conductors. Compared with the existing line without an air bridge, the planar waveguide ground wire connection structure can realize the connection of the planar waveguide ground wires, enable the planar waveguides to pass through in a crossed mode, can enhance the circuit stability, can construct a complex circuit structure, and has important significance in a micron superconducting microwave circuit.
For superconducting lines, it is common to work in vacuum and at low temperatures, and therefore it is necessary to prepare superconducting vacuum bridges. For superconducting lines based on aluminum films, aluminum is generally used as the superconducting vacuum bridge. However, the aluminum vacuum bridge has the disadvantage of weak contact strength, and is generally not capable of performing multiple chip gluing and stripping processes, so that the length of the vacuum bridge is greatly limited.
In Micro-Electro-Mechanical systems (MEMS), Polymethylglutarimide (PMGI) is commonly used in the art as a sacrificial release layer to fabricate the air bridge and the cantilever. In the production method using PMGI as the sacrificial layer, there are problems as follows: firstly, the photoresist needs to be subjected to mask exposure and development, and in an actual process, only the photoresist is developed without involving a PMGI layer, which is difficult to control; secondly, deep ultraviolet flood exposure is carried out on the PMGI and development is carried out by utilizing a developing solution, and the photoresist is removed by utilizing the developing solution in the PMGI developing process; the process needs to respectively carry out two times of exposure and development on photoresist and PMGI, and simultaneously also relates to deep ultraviolet flood exposure and mask exposure, the photoresist removing process is complicated and the development degree is difficult to control, so that the problems that the PMGI is also dissolved by the developing solution and the bridge arch height is inconsistent due to improper control of the development time are easily caused; third, satisfying the parameters of both developing PMGI and removing photoresist does not allow the preparation of vacuum bridges longer than 10 μm, and therefore, the preparation method using PMGI as a sacrificial layer is not applicable to the preparation of superconducting vacuum bridges.
In summary, it is necessary to provide a method suitable for preparing a longer (more than 10 microns) superconducting vacuum bridge with a simple process.
Disclosure of Invention
Technical problem to be solved
The present disclosure provides a superconducting vacuum bridge and a method for manufacturing the same to at least partially solve the technical problems set forth above.
(II) technical scheme
According to an aspect of the present disclosure, there is provided a method of manufacturing a superconducting vacuum bridge, including: spin-coating an LOR material on a substrate to serve as an LOR sacrificial layer; spin-coating a first photoresist on the LOR sacrificial layer, and performing mask exposure, wherein the mask exposure defines the position of the bridge pier; carrying out first development to obtain three-dimensional structures of a pier and a bridge arch; removing unexposed photoresist on the bridge arch by utilizing the solubility difference between the first photoresist and the LOR material in acetone; heating and refluxing the LOR material at the bridge arch at a set temperature to obtain an edge rounded bridge arch; sequentially spin-coating an LOR layer and a second photoresist on the edge arched arch bridge; exposing the second photoresist and carrying out second development; evaporating a superconducting metal layer; and releasing the LOR sacrificial layer below the bridge arch of the superconducting metal layer and the structure at the position of the non-superconducting bridge to obtain the superconducting vacuum bridge.
In some embodiments of the present disclosure, in the step of performing the first development to obtain the three-dimensional structures of the bridge pier and the bridge arch, the first development is performed, and the first photoresist and the LOR sacrificial layer at the position of the bridge pier, which corresponds to the exposure of the mask, are removed by the developer in the first development process, so as to obtain the three-dimensional structures of the bridge pier and the bridge arch.
In some embodiments of the present disclosure, in the exposing the second photoresist and performing the second developing, the second photoresist is exposed, and the second photoresist and the LOR layer at the positions corresponding to the exposed bridge piers and arches are removed by the developing solution in the second developing process.
In some embodiments of the present disclosure, exposing the second photoresist is performed using a maskless laser direct writing technique.
In some embodiments of the present disclosure, exposing the second photoresist uses a mask for exposure.
In some embodiments of the present disclosure, the developing solution of the first development is: MF319 or AZ 400K; and/or the developing solution for the second development is: MF319 or AZ 400K.
In some embodiments of the present disclosure, the set temperature is between 250-300 ℃. .
In some embodiments of the present disclosure, the first photoresist and the second photoresist are S18 series photoresists.
In some embodiments of the present disclosure, the method of releasing the LOR sacrificial layer under the superconducting metal layer bridge arch and the structure at the non-superconducting bridge location is: and soaking the structure in a solvent Remover PG to release the LOR sacrificial layer and the structure at the position of the non-superconducting bridge.
According to another aspect of the present disclosure, there is provided a superconducting vacuum bridge, wherein the superconducting vacuum bridge is manufactured by any one of the methods for manufacturing a superconducting vacuum bridge mentioned in the present disclosure.
(III) advantageous effects
According to the technical scheme, the superconducting vacuum bridge and the preparation method thereof have the following beneficial effects:
(1) utilizing the found solubility difference between a Lift-off-resist (LOR) material and a micro-nano common photoresist for manufacturing, namely the common photoresist is easily dissolved in an acetone reagent, and the LOR is completely insoluble to acetone, spinning the photoresist on an LOR sacrificial layer and carrying out mask exposure, removing the photoresist and the LOR at the position of the pier corresponding to exposure by a developing solution to obtain a three-dimensional structure of the pier and a bridge arch, and directly removing the photoresist by using acetone through utilizing the solubility difference of the photoresist and the LOR; the process of flood exposure and photoresist removal by adopting a developing solution is not required, the problem of poor consistency control of the bridge arch height caused by the dissolution of a solvent in the developing process after the flood exposure of the LOR is essentially avoided, and the flood exposure equipment and the multiple developing processes are not required, so that the process equipment is greatly simplified from the aspects of use of the process equipment and operation of the process flow;
(2) aiming at a superconducting device, a common superconducting material is Al, but an Al film can form a compact oxide layer at normal temperature due to the active property, so that the scheme ensures the removal of the oxide layer on the surface of the Al layer before depositing a superconducting metal layer in the preparation process of the superconducting vacuum bridge so as to ensure the superconducting property of the vacuum bridge;
(3) in the aspect of sacrificial layer release, because the Al film has active properties, the degumming agent Remover PG with lower requirement on degumming temperature is used as a dissolving agent of the LOR sacrificial layer, so that the performance influence on the existing devices on the superconducting chip in the sacrificial layer release process is reduced.
Drawings
Fig. 1 is a flowchart illustrating a method for fabricating a superconducting vacuum bridge according to an embodiment of the present disclosure.
FIG. 2 is a schematic structural diagram corresponding to each step of the process of the preparation method shown in FIG. 1.
Table 1 shows the dimensional and morphological parameters of the prepared superconducting vacuum bridge according to an embodiment of the present disclosure.
[ notation ] to show
11-a substrate; 12-LOR sacrificial layer;
13-a first photoresist; 14-a first mask;
15-bridge pier; 121-bridge arch;
131-unexposed photoresist;
122-profile after edge rounding bridge arching/reflowing;
161-LOR layer; 162-a second photoresist;
17-a second mask plate; 18-superconducting metal layer.
Detailed Description
The invention provides a superconductive vacuum bridge and a preparation method thereof, wherein a three-dimensional structure of a bridge pier and a bridge arch is manufactured on an LOR sacrificial layer and a photoresist by adopting mask exposure, and the graph and the position of the superconductive bridge are defined by photoetching, so that the deposition of superconductive metal on the bridge pier and the bridge arch is realized, and the superconductive vacuum bridge is obtained after the sacrificial layer is removed; the photoresist is removed by utilizing the solubility difference of the photoresist and the LOR in acetone, the oxide film is removed before the superconducting metal layer is deposited to ensure the superconducting characteristic, the process of flood exposure and the removal of the photoresist by adopting a developing solution is not needed, the problem of poor consistency control of the bridge arch height caused by the dissolution of the LOR by a solvent in the developing process after the flood exposure is essentially avoided, and the flood exposure equipment and multiple developing processes are not needed, so that the use of process equipment and the operation of process flow are greatly simplified.
For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings. In the present disclosure, "photoresist" refers to a common photoresist, not including LOR photoresist. The term "between" is inclusive of the endpoints.
In the prior art, the preparation method using PMGI as the sacrificial layer mainly comprises the following steps:
(1) spin-coating a plurality of layers of PMGI, and spin-coating photoresist;
(2) carrying out mask exposure and development on the photoresist;
(3) carrying out deep ultraviolet flood exposure on the PMGI;
(4) developing the PMGI, and removing the photoresist by a developing solution;
(5) refluxing the PMGI layer;
(6) spin-coating a photoresist;
(7) exposing the photoresist through a mask;
(8) developing the photoresist;
(9) depositing a metal layer;
(10) and stripping the PMGI, the photoresist and the upper layer metal to obtain the bridge structure.
The preparation method using PMGI as the sacrificial layer can be used to prepare vacuum bridges with a length of less than 10 microns, but the preparation method using PMGI as the sacrificial layer is no longer applicable for the preparation of superconducting vacuum bridges, in particular:
1. in step (2), in an actual process, it is difficult to control only to develop the photoresist without involving the PMGI layer; in the steps (3) and (4), deep ultraviolet flood exposure is carried out on the PMGI, and development is carried out by using a developing solution, and the photoresist is removed by using the developing solution in the PMGI development process; the process needs to respectively carry out two times of exposure and development on photoresist and PMGI, and simultaneously also relates to deep ultraviolet flood exposure and mask exposure, the photoresist removing process is complicated and the development degree is difficult to control, so that the problems that the PMGI is also dissolved by the developing solution and the bridge arch height is inconsistent due to improper control of the development time are easily caused;
2. the vacuum bridge with the length of more than 10 microns cannot be prepared by meeting the parameters of developing PMGI and removing photoresist simultaneously in the step (4);
3. when the metal in step (9) is aluminum, the deposited superconducting metal does not have an oxide layer to ensure superconducting contact.
Through the analysis of the prior art, the invention provides a superconducting vacuum bridge and a preparation method thereof, wherein an LOR is adopted as a sacrificial layer in the preparation method of the superconducting vacuum bridge, and when the LOR is selected as the sacrificial layer, the defect of poor consistency control of the bridge arch height caused by the dissolution of the LOR by a solvent in the development process after flood exposure is overcome through a design process, and the preparation process is simplified to a great extent.
In a first exemplary embodiment of the present disclosure, a method of fabricating a superconducting vacuum bridge is provided.
Fig. 1 is a flowchart illustrating a method for fabricating a superconducting vacuum bridge according to an embodiment of the present disclosure. FIG. 2 is a schematic structural diagram corresponding to each step of the process of the preparation method shown in FIG. 1.
Referring to fig. 1 and 2, a method for manufacturing a superconducting vacuum bridge according to the present disclosure includes:
step S11: spin-coating an LOR material on a substrate to serve as an LOR sacrificial layer;
in this embodiment, the substrate 11 is cleaned to clean the surface of the substrate 11, and the substrate 11 is shown in fig. 2 (a); in order to highlight the characteristics of the sacrificial layer 12, which is spin-coated with LOR material on the substrate 11, the present disclosure refers to the sacrificial layer as LOR sacrificial layer 12, the thickness of the LOR sacrificial layer 12 is H, and the thickness H determines the height of the bridge arch of the superconducting vacuum bridge, as shown in (b) and (j) in fig. 2, in one embodiment, the spin-coated LOR may be a single layer or multiple layers.
Step S12: spin-coating a first photoresist on the LOR sacrificial layer, and performing mask exposure, wherein the mask exposure defines the position of the bridge pier;
in this embodiment, in order to make the exposure region easily soluble in the developing solution and improve the resolution, the first photoresist is preferably a positive photoresist, where S1805 is taken as an example, a person skilled in the art may select the positive photoresist according to actual needs, and other types of positive photoresists are also within the protection scope of the present disclosure.
Spin-coating a first photoresist 13 on the LOR sacrificial layer 12, and performing mask exposure by using a first mask plate 14 as a mask, wherein the mask exposure defines the position of a bridge pier; the pattern of the first mask 14 is shown in fig. 2 (c), the exposed area is defined as the position of a bridge pier, the unfilled area is shown in the figure, the unexposed area is defined as the position of a bridge arch, and the filled area is shown in the figure.
Step S13: carrying out first development, and removing the first photoresist and the LOR sacrificial layer at the position of the pier corresponding to the mask exposure by developing solution to obtain a three-dimensional structure of the pier and the bridge arch;
in this embodiment, the developer is MF319 or AZ400K, and since the photoresist has photosensitive property, the photoresist is dissolved in the developer after exposure, and the LOR photoresist is not photosensitive but dissolved in the developer, so that the developer is used to remove the first photoresist and LOR sacrificial layer at the pier position where the mask is exposed, and the first photoresist and LOR sacrificial layer at the pier position where the corresponding mask is exposed are both removed by the developer, as shown in fig. 2 (d), a space corresponding to the pier 15 is obtained, and the LOR sacrificial layer is left as the bridge arch 121, and the unexposed photoresist 131 is located above the bridge arch 121.
Step S14: removing unexposed photoresist on the bridge arch by utilizing the solubility difference between the first photoresist and the LOR material in acetone;
tests show that the solubility difference exists between the LOR material and the micro-nano manufacturing common photoresist, the micro-nano manufacturing common photoresist is easily dissolved in an acetone reagent, the LOR material is completely insoluble to acetone, and based on the solubility difference, the unexposed photoresist 131 on the bridge arch 121 is removed by using the acetone, so that the obtained structure is shown in (e) in fig. 2.
The step S14 is set because heating is performed in the subsequent process, and the photoresist has poor temperature resistance, which is not beneficial to the later peeling, so that the unexposed photoresist on the bridge arch is removed by using acetone due to the difference in solubility.
Step S15: heating and refluxing the LOR material at the bridge arch at a set temperature to obtain an edge rounded bridge arch;
in this embodiment, the LOR material at the bridge arch is heated and reflowed at a set temperature, for example, between 250 ℃ and 300 ℃, the set temperature of the present disclosure is not limited to the embodiment shown, and any reasonable temperature that can be adaptively set by those skilled in the art according to actual needs is within the protection range. By utilizing the temperature resistance and reflow characteristics of the LOR material, an edge rounded bridge arch 122 is obtained, and the three-dimensional topography of the edge rounded bridge arch 122 is shown in fig. 2 (f).
Step S16: sequentially spin-coating an LOR layer and a second photoresist on the edge arched arch bridge;
the structure of spin coating the LOR layer 161 and the second photoresist 162 on the edge rounded arch bridge 122 in sequence is shown in fig. 2 (g), in this embodiment, the second photoresist is exemplified by a photoresist S1813.
Step S17: exposing the second photoresist, carrying out second development, and removing the second photoresist and the LOR layer at the positions of the exposed bridge pier and the exposed bridge arch by the developing solution;
in this embodiment, the second photoresist is exposed by using the second mask 17 as a mask, the pattern of the second mask 17 is shown in (h) of fig. 2, an exposure area is defined as a position of a bridge pier and a bridge arch, a non-filled area is shown in the figure, a non-exposure area is defined as a position of a non-superconducting bridge, and a block filled with oblique lines is shown in the figure.
In other embodiments, the exposure may also be performed by using a maskless laser direct writing technique, and the exposure of the second photoresist may be performed without using the second mask 17 as shown in fig. 2 (h). After the second photoresist is exposed, the second development is performed, in this embodiment, the developing solution uses MF319 or AZ400K, and for the same reason as that in step S13, the second photoresist and LOR layer at the bridge pier and bridge arch positions corresponding to the exposure are removed by the developing solution, and the structure after the second photoresist and LOR layer at the bridge pier and bridge arch positions are removed is (i) the structure without the superconducting metal layer 18 in fig. 2.
Step S18: evaporating a superconducting metal layer;
the material of the superconducting metal layer can be aluminum, titanium, niobium, and other superconducting materials, and the material can be a single layer of superconducting material, or two or more layers of different superconducting materials. To enhance the stability of the vacuum bridge in subsequent processes, in a preferred embodiment, a 200nmAl +900nmTi bimetallic superconducting bridge process is used. In this embodiment, the material of the superconducting metal layer is Al, and the removal of the oxide layer on the surface of the Al layer is ensured before the deposition of the superconducting metal layer, so as to ensure the superconducting property of the vacuum bridge. In one example, in order to ensure that the contact between the superconducting vacuum bridge and the substrate pattern is superconducting contact, controllable Ar ion physical bombardment is carried out before the Al film is evaporated in ultrahigh vacuum, so that an oxide layer on the surface of the Al layer can be removed, superconducting contact is realized, and the influence on the performance of a device caused by defects on an Al layer substrate is avoided. In other examples, to ensure that the contact between the superconducting vacuum bridge and the substrate pattern is superconducting, the oxide layer may be removed using an etchant that does not affect other structures and the photoresist.
After the second development, a layer of superconducting metal 18 is evaporated, the layer of superconducting metal 18 being on top of the LOR sacrificial layer in the position of the bridge arch and in contact with the substrate, forming a solid vacuum superconducting bridge, see fig. 2 (i), where the arrows indicate the direction of illumination of the mask exposure, the bridge arch height of the vacuum superconducting bridge being dependent on the height of the LOR sacrificial layer 12.
Step S19: releasing the LOR sacrificial layer below the bridge arch of the superconducting metal layer and the structure at the position of the non-superconducting bridge to obtain a superconducting vacuum bridge;
from the aspect of device performance, vacuum (dielectric constant is 1) is required between the bridge and the superconducting line below the bridge when the device works, namely the superconducting vacuum bridge requires that the sacrificial layer is completely removed in the release process, the solvent for dissolving the sacrificial layer is not easy to generate residues, and the solvent for releasing cannot be matched with the prepared superconducting lineA reaction occurs therebetween. In this embodiment, since the Al film is active, the Remover PG having a neutral chemical property and a lower requirement for the removal temperature is first used as a solvent for the LOR sacrificial layer, and the structure at the non-superconducting bridge position is also immersed in the solvent for removal; however, since Remover PG itself is not easy to volatilize and vacuum bridges cannot be directly dried from Remover PG solution, the prepared superconducting vacuum bridge sample is replaced from RemoverPG solution to easily volatilized organic solvent such as isopropanol solution by utilizing good mutual solubility of RemoverPG and organic solvent and a solution replacement mode, and high-purity N is used2The isopropyl alcohol is volatilized and dried to obtain a superconducting vacuum bridge structure with reliable performance, and as shown in (j) in fig. 2, the performance influence on the existing devices on the superconducting chip in the sacrificial layer release process can be effectively reduced.
LOR used as a sacrificial layer is still easy to remove after being subjected to a thermal reflux process and physical attack etching, and residues are not easy to form in the releasing process of the superconducting vacuum bridge; by selecting a proper replacement solution, the performance of the superconducting device cannot be reduced due to the introduction of other dielectric layers in the process of taking the superconducting vacuum bridge out of the solution and drying the superconducting vacuum bridge, and the adsorption collapse cannot be caused due to the influence of capillary force (if the replacement is carried out by using an aqueous solution, the risk of the adsorption collapse is generated).
The length of the obtained superconducting vacuum bridge can reach more than 10 microns, and in one example, by using the preparation method of the superconducting vacuum bridge shown in the embodiment, when the LOR spin coating thickness is 2.4 microns, the superconducting vacuum bridge with the span of 60 microns and the bridge arch height (also called bridge height or arch height) of 0.8 microns can be obtained; in another example, a superconducting vacuum bridge with a span of 36 μm and a bridge arch height of 2 μm can be obtained under the same LOR thickness condition.
The morphology of the superconducting vacuum bridge is mainly determined by two parameters, the span and the bridge height, which are directly related to the size of the LOR sacrificial layer 12 and its morphology 122 after reflow. The LOR is in the thermoplastic flowing process of hot reflow into high polymer material between set temperature (such as 250 ℃ -300 ℃), and the morphology after reflow is in a dome shape because of the influence of surface tension. However, when the ratio of the span of the bridge to the thickness of the sacrificial layer is larger than a certain ratio, the influence of the thermal reflux is not enough to form a circular arch at the bridge arch, the LOR at the midpoint of the bridge arch flows to the step to form a circular arc under the action of surface tension, and the LOR height at the midpoint of the original bridge arch is reduced along with the loss of the high polymer material, so that an M-shaped bridge arch is generated. The height of the M-shaped bridge arch at the center of the bridge is far lower than the height of the applied LOR sacrificial layer 12 and is also far lower than the height near the bridge pier. With the reduction of the thickness of the spin-coating LOR, the arch height of the large-span vacuum bridge is reduced sharply, on one hand, the introduction of overlarge parasitic capacitance (when the arch height is less than 0.9 mu M) can be reduced, the performance of a device is reduced, on the other hand, the bridge deck is directly adsorbed with bottom metal (especially the central position of an M-shaped bridge arch) due to the influence of the surface tension of a solution in the releasing process, and a suspended superconducting vacuum bridge structure cannot be obtained.
In the scheme of preparing the superconducting vacuum bridge by using the PMGI as the sacrificial layer, because the thickness of the spin coating of the PMGI is limited and is generally less than 1.5 mu M, when the span is more than 10 mu M, the height of the vacuum bridge is too low and even the adsorption collapse of the bridge deck is caused by the influence of the reflowed M-shaped bridge arch. The LOR has various specifications, and the spin coating thickness can reach more than 5 mu m by selecting the proper specification, so that the superconducting vacuum bridge with larger span is obtained.
In a second exemplary embodiment of the present disclosure, a superconducting vacuum bridge manufactured by the above-described manufacturing method is provided.
In this embodiment, the dimensions and morphology of the superconducting vacuum bridge obtained by the above preparation method are shown in table 1. In this embodiment, under the same process conditions, for example, when the spin-coating thickness of the LOR sacrificial layer 12 is 2.4 μm, the shapes and heights of the superconducting vacuum bridges with different spans are obtained, wherein the arch height is calculated as the lowest arch of the bridge.
The preparation method of the superconducting vacuum bridge using the LOR as the sacrificial layer has the following advantages:
1. the process compatibility is strong, and the LOR can be used as a common process for stripping photoresist and can be matched with various photosensitive high polymer materials (positive photoresist, negative photoresist and the like) for use according to requirements;
2. the process flow is simplified, only two steps of exposure and development are needed, and thermal reflux and acetone photoresist removal are matched;
3. the height of the bridge arch is not influenced by the photoresist removing process and is only determined by the LOR thickness and the bridge arch span, so that the process consistency is strong;
4. the process reliability is high: the releasing and drying process of the superconducting vacuum bridge can effectively control residues under the bridge arch, does not influence the appearance of the bridge, and can effectively guarantee the qualification rate of the superconducting vacuum bridge;
5. the size parameter of the superconducting vacuum bridge has a wide selectable range, and can be suitable for the design requirements of different superconducting devices.
In summary, the disclosure provides a superconducting vacuum bridge and a preparation method thereof, wherein a mask is used for exposure on an LOR sacrificial layer and a photoresist to manufacture a three-dimensional structure of a bridge pier and a bridge arch, and photoetching is carried out to define the graph and the position of the superconducting bridge, so as to realize deposition of superconducting metal on the bridge pier and the bridge arch, and the superconducting vacuum bridge is obtained after the sacrificial layer is removed; the photoresist is removed by utilizing the solubility difference of the photoresist and the LOR in acetone, the oxide film is removed before the superconducting metal layer is deposited to ensure the superconducting characteristic, the process of flood exposure and the removal of the photoresist by adopting a developing solution is not needed, the problem of poor consistency control of the bridge arch height caused by the dissolution of the LOR by a solvent in the developing process after the flood exposure is essentially avoided, and the flood exposure equipment and multiple developing processes are not needed, so that the process equipment is greatly simplified from the aspects of use and process flow operation; in the aspect of sacrificial layer release, due to the fact that the Al film is active, PG remover with lower photoresist removing temperature requirement is used as a dissolving agent of the LOR sacrificial layer, and therefore the performance influence of the sacrificial layer on existing devices on the superconducting chip in the release process is reduced.
It should be noted that directional terms, such as "upper", "lower", "front", "rear", "left", "right", and the like, mentioned in the embodiments are only directions referring to the drawings, and are not intended to limit the scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. Conventional structures or constructions will be omitted when they may obscure the understanding of the present disclosure.
And the shapes and sizes of the respective components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure. Furthermore, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.
The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify a corresponding element does not by itself connote any ordinal number of the element or any ordering of one element from another or the order of manufacture, and the use of the ordinal numbers is only used to distinguish one element having a certain name from another element having a same name.
Furthermore, the word "comprising" or "comprises" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.
In addition, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e., technical features in different embodiments may be freely combined to form further embodiments.
The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.
Claims (10)
1. A method for preparing a superconducting vacuum bridge comprises the following steps:
spin-coating an LOR material on a substrate to serve as an LOR sacrificial layer;
spin-coating a first photoresist on the LOR sacrificial layer, and performing mask exposure, wherein the mask exposure defines the position of the bridge pier;
carrying out first development to obtain three-dimensional structures of a pier and a bridge arch;
removing unexposed photoresist on the bridge arch by utilizing the solubility difference between the first photoresist and the LOR material in acetone;
heating and refluxing the LOR material at the bridge arch at a set temperature to obtain an edge rounded bridge arch;
sequentially spin-coating an LOR layer and a second photoresist on the edge arched arch bridge;
exposing the second photoresist and carrying out second development;
evaporating a superconducting metal layer; and
and releasing the LOR sacrificial layer below the bridge arch of the superconducting metal layer and the structure at the position of the non-superconducting bridge to obtain the superconducting vacuum bridge.
2. The production method according to claim 1, wherein in the step of performing the first development to obtain the three-dimensional structure of the bridge pier and the bridge arch, the first development is performed such that the first photoresist and the LOR sacrificial layer at the bridge pier position corresponding to the mask exposure are removed by the developing solution in the first development process, thereby obtaining the three-dimensional structure of the bridge pier and the bridge arch.
3. The method of claim 1, wherein the exposing the second photoresist and performing the second developing step expose the second photoresist, and the second photoresist and the LOR layer corresponding to the exposed bridge pier and arch positions are removed by the developing solution during the second developing step.
4. The production method according to claim 1, wherein the exposing the second photoresist is performed by a maskless laser direct writing technique.
5. The production method according to claim 1, wherein the exposing the second photoresist is performed with a mask.
6. The production method according to claim 1,
the developing solution for the first development is: MF319 or AZ 400K; and/or the presence of a gas in the gas,
the developing solution for the second development is: MF319 or AZ 400K.
7. The method of claim 1, wherein the set temperature is between 250-300 ℃.
8. The production method according to claim 1, wherein the first photoresist and the second photoresist are S18 series photoresists.
9. The method for preparing according to claim 1, wherein the method for releasing the LOR sacrificial layer under the bridge arch of the superconducting metal layer and the structure at the position of the non-superconducting bridge is as follows:
and soaking the structure in a solvent Remover PG to release the LOR sacrificial layer and the structure at the position of the non-superconducting bridge.
10. A superconducting vacuum bridge, wherein the superconducting vacuum bridge is produced by the production method of any one of claims 1 to 9.
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| CN101276778A (en) * | 2007-03-28 | 2008-10-01 | 中国科学院微电子研究所 | Method for preparing air bridge using photosensitive subbing |
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