Photosensitive polyimide composite titanium film and preparation method and application thereof

Abstract

The invention provides a photosensitive polyimide composite titanium film and a preparation method and application thereof. The photosensitive polyimide composite titanium film comprises a photosensitive polyimide base film, a transition bonding layer and a titanium layer, wherein the transition bonding layer and the titanium layer are sequentially stacked on the surface of the photosensitive polyimide base film; the surface of one side, close to the transition bonding layer, of the photosensitive polyimide base film contains a polar functional group. Through the synergistic effect of chemical anchoring of the polar functional group and molecular bridging of the transition bonding layer, the problems that the binding force between photosensitive polyimide and titanium is weak and the photosensitive polyimide is easy to strip are fundamentally solved, and the aspects of binding force, thermal stability, environmental tolerance and the like of the photosensitive polyimide composite titanium film are obviously improved.

Description

Technical Field

[0001] This invention belongs to the field of microelectronics manufacturing technology, and relates to a photosensitive polyimide composite titanium film, its preparation method and application. Background Technology

[0002] Photosensitive polyimide (PSPI) is widely used in semiconductor packaging, flexible circuits, and microelectromechanical systems (MEMS) devices due to its excellent electrical insulation, heat resistance, and photolithography properties. In subsequent metallization processes, a titanium thin film is typically deposited on the PSPI surface as an adhesion or barrier layer.

[0003] However, PSPI is an organic polymer with low surface energy and a tendency to absorb moisture, leading to insufficient adhesion between the deposited titanium film and the substrate, often resulting in delamination, peeling, and other failures. Existing improvement methods mainly include plasma roughening, surface hardening, or increasing the curing temperature, but these methods have drawbacks such as narrow process windows, insufficient stability, or adverse effects on the material's electrical properties.

[0004] CN1669788A discloses a metallized polyimide film having the following structure: a polyimide film having a first side and a second side; on the first side of the polyimide film, a metallized polyimide film having ... 2 An intermediate layer is formed by attaching one, two or more elements selected from Mo, Cr, Ni, Si, Fe and Al to the intermediate layer; and a conductive layer made of copper or a copper alloy is formed on the intermediate layer.

[0005] CN101950605A discloses a process for obtaining porous high-purity anatase phase titanium dioxide thin films on the surface of flexible substrate materials, including flexible substrate rinsing, ion bombardment cleaning, DC / RF magnetron sputtering deposition of a chromium transition layer and a titanium nanofilm on the flexible substrate, and in-situ acquisition of porous high-purity anatase phase titanium dioxide thin films with preferred orientation by plasma micro-arc oxidation.

[0006] In the composite film obtained by the above-described method of bonding metal onto a polyimide film, the bonding strength between the metal and the substrate is poor, which directly affects its structural stability. Therefore, there is an urgent need for a titanium composite PSPI film with higher bonding strength. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a photosensitive polyimide composite titanium film, its preparation method, and its application. The present invention fundamentally solves the problems of weak bonding and easy peeling between photosensitive polyimide and titanium through the synergistic effect of polar functional group chemical anchoring and transition bonding layer molecular bridging. The photosensitive polyimide composite titanium film has been significantly improved in terms of bonding strength, thermal stability, and environmental resistance.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a photosensitive polyimide composite titanium film, the photosensitive polyimide composite titanium film comprising a photosensitive polyimide base film and a transition bonding layer and a titanium layer sequentially stacked on the surface of the photosensitive polyimide base film;

[0010] The surface of the photosensitive polyimide-based film near the transition bonding layer contains polar functional groups.

[0011] This invention introduces polar functional groups on the surface of a photosensitive polyimide-based film. Strong chemical bonds exist between the polar functional groups and the transition bonding layer, resulting in extremely high bonding strength. Titanium is a very reactive metal with a strong affinity for oxygen. The transition bonding layer interacts with the highly reactive titanium atoms to form Ti-OM (M is silicon and / or aluminum) chemical bonds. These chemical bonds make the interfacial bonding strength much higher than the weak physical adsorption that may occur when titanium is directly deposited on an untreated photosensitive polyimide film. This significantly improves the bonding force between the titanium layer and the transition bonding layer, thereby obtaining a photosensitive polyimide composite titanium film with strong bonding strength.

[0012] Preferably, the polar functional group includes any one or a combination of at least two of hydroxyl, carboxyl, or amino groups. Typical but non-limiting combinations include combinations of cyano and carboxyl, carboxyl and amino, or hydroxyl and amino groups.

[0013] Preferably, the material of the transition bonding layer includes silicon oxide and / or aluminum oxide.

[0014] Preferably, the thickness of the transition bonding layer is 2nm to 5nm, for example: 2nm, 2.5nm, 3nm, 4nm or 5nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] Preferably, the thickness of the titanium layer is 80nm~120nm, for example: 80nm, 90nm, 100nm, 110nm or 120nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] In a second aspect, the present invention provides a method for preparing a photosensitive polyimide composite titanium film as described in the first aspect, the method comprising the following steps:

[0017] Surface treatment is performed on one side of the photosensitive polyimide-based film;

[0018] A transition bonding layer is deposited on the surface of the photosensitive polyimide-based film after surface treatment;

[0019] A titanium layer is sputtered onto the transition bonding layer to obtain the photosensitive polyimide composite titanium film.

[0020] This invention pre-treats the surface of the photosensitive polyimide-based film, introducing polar groups on the surface of the film to provide chemical bonding sites for the next deposition of the transition bonding layer. The deposited transition bonding layer can form strong chemical bonds with both the polar functional groups on the PSPI surface and the upper titanium layer, acting as a bridge. After sputtering the titanium layer, the high-strength interface between the transition bonding layer and the titanium layer gives the product extremely strong resistance to damp heat and corrosion, resulting in a longer service life.

[0021] Preferably, the photosensitive polyimide-based film is cured before surface treatment.

[0022] Preferably, the curing temperature is 200℃~250℃, for example: 200℃, 210℃, 220℃, 230℃, 240℃ or 250℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] Preferably, the curing time is 0.5h to 1.5h, for example: 0.5h, 0.8h, 1h, 1.2h or 1.5h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] Preferably, the surface treatment method includes, but is not limited to, the listed values; other unlisted values ​​within this range are also applicable to plasma treatment and / or ion beam treatment.

[0025] Preferably, the environmental vacuum degree of the surface treatment is 2×10⁻⁶. -6 Torr~4×10 -6 Torr, for example: 2×10 - 6 Torr, 2.5×10 -6 Torr, 3×10 -6 Torr, 3.5×10 -6 Torr or 4×10 -6 Torr, etc., are not limited to the listed values; other unlisted values ​​within this range also apply.

[0026] Preferably, the elements used in the surface treatment include oxygen and / or nitrogen.

[0027] Preferably, the power of the surface treatment is 30W to 80W, for example: 30W, 40W, 60W, 70W or 80W, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] Preferably, the surface treatment time is 30s to 90s, for example: 30s, 50s, 60s, 80s or 90s, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] Preferably, the surface treatment is followed by vacuum baking.

[0030] Preferably, the temperature of the vacuum baking process is 150℃~200℃, for example: 150℃, 160℃, 180℃, 190℃ or 200℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] Preferably, the vacuum baking time is 20 min to 40 min, for example: 20 min, 25 min, 30 min, 35 min or 40 min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] Preferably, the deposition of the transition bonding layer includes atomic layer deposition (ALD).

[0033] Preferably, the sputtered titanium layer comprises a first sputtering and a second sputtering.

[0034] Preferably, the growth rate of the first sputtering is 0.05 nm / s to 0.1 nm / s, for example: 0.05 nm / s, 0.06 nm / s, 0.08 nm / s, 0.09 nm / s or 0.1 nm / s, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] Preferably, the thickness of the titanium layer obtained by the first sputtering is 10nm~30nm, for example: 10nm, 15nm, 20nm, 25nm or 30nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Preferably, the growth rate of the second sputtering is 0.2 nm / s to 0.4 nm / s, for example: 0.2 nm / s, 0.25 nm / s, 0.3 nm / s, 0.35 nm / s or 0.4 nm / s, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the thickness of the titanium layer obtained by the second sputtering is 40nm~110nm, for example: 40nm, 50nm, 80nm, 100nm or 110nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] This invention first employs slow sputtering, where the gradual deposition allows titanium atoms to fully react with oxygen atoms on the surface of the transition bonding layer, forming a continuous, pore-free, and chemically perfectly bonded initial titanium layer. This initial titanium layer covers and "passivates" the underlying transition bonding layer, providing a robust and stable substrate for subsequent rapid deposition. After the initial titanium layer is established, increasing the deposition rate allows for rapid deposition of the titanium layer to the target thickness, ensuring production efficiency. At the same time, rapid deposition helps to form a better crystal structure, improving the quality of the obtained titanium layer.

[0039] Preferably, the sputtered titanium layer is further annealed.

[0040] This invention releases the stress in the titanium layer through annealing, reducing poor adhesion caused by stress problems and further improving the performance of the prepared photosensitive polyimide composite titanium film.

[0041] Preferably, the annealing temperature is 200℃~300℃, for example: 200℃, 220℃, 250℃, 280℃ or 300℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Preferably, the annealing time is 40 min to 80 min, for example: 40 min, 50 min, 60 min, 70 min or 80 min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] Preferably, the annealing atmosphere includes nitrogen and / or argon.

[0044] Thirdly, the present invention provides an application of the photosensitive polyimide composite titanium film as described in the first aspect, wherein the photosensitive polyimide composite titanium film is used in any one or a combination of at least two of semiconductor packaging, flexible circuits, or microelectromechanical systems devices.

[0045] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) This invention fundamentally solves the problem of weak bonding force and easy peeling between photosensitive polyimide and titanium through the synergistic effect of polar functional group chemical anchoring and transition bonding layer molecular bridging. The photosensitive polyimide composite titanium film has been significantly improved in terms of bonding force, thermal stability and environmental tolerance.

[0048] (2) The present invention uses a progressive deposition method to form a good bond between the titanium layer and the transition layer, avoiding problems such as coarse crystals and porosity caused by direct rapid deposition.

[0049] (3) The peel strength of the photosensitive polyimide composite titanium film of the present invention can reach more than 11.3 N / cm. Detailed Implementation

[0050] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0051] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0052] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0053] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0054] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0055] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0056] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0057] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0058] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0059] In this invention, "optional" means that something is optional, that is, it refers to any one of the two parallel solutions of "having" or "not having". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0060] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0061] Example 1

[0062] This embodiment provides a photosensitive polyimide composite titanium film, which includes a photosensitive polyimide base film and an alumina transition bonding layer and a titanium layer sequentially stacked on the surface of the photosensitive polyimide base film. The surface of the photosensitive polyimide base film near the alumina transition layer contains carboxyl groups and hydroxyl groups.

[0063] The thickness of the alumina transition bonding layer is 3 nm, and the thickness of the titanium layer is 100 nm.

[0064] The photosensitive polyimide composite titanium film was prepared by the following method:

[0065] The photosensitive polyimide film was cured at 230°C for 1 hour, then placed in a plasma treatment device and evacuated to a vacuum of 3×10⁻⁶. -6 Torr, using oxygen plasma, is treated at 50W power for 60s and then vacuum baked at 180℃ for 30min to complete the surface treatment;

[0066] An aluminum oxide transition bonding layer with a thickness of 3 nm was deposited on the surface of the photosensitive polyimide film after surface treatment by ALD.

[0067] A 20 nm titanium layer was first sputtered onto the alumina transition bonding layer at a growth rate of 0.08 nm / s, followed by sputtering an 80 nm titanium layer at a rate of 0.3 nm / s to form a 100 nm thick titanium layer. The titanium layer was then annealed at 250 °C for 60 min to obtain the photosensitive polyimide composite titanium film.

[0068] Example 2

[0069] This embodiment provides a photosensitive polyimide composite titanium film, which includes a photosensitive polyimide base film and a silicon oxide transition bonding layer and a titanium layer sequentially stacked on the surface of the photosensitive polyimide base film. The surface of the photosensitive polyimide base film near the silicon oxide transition bonding layer contains carboxyl groups and hydroxyl groups.

[0070] The thickness of the silicon oxide transition bonding layer is 2 nm, and the thickness of the titanium layer is 80 nm.

[0071] The photosensitive polyimide composite titanium film was prepared by the following method:

[0072] The photosensitive polyimide film was cured at 200℃ for 1.5 h, then placed in a plasma treatment device and evacuated to a vacuum of 2×10⁻⁶. -6 Torr, using oxygen plasma, is treated at 30W power for 90s and then vacuum baked at 150℃ for 40min to complete the surface treatment;

[0073] A 2nm thick silicon oxide transition bonding layer is deposited on the surface of the photosensitive polyimide film after surface treatment by ALD.

[0074] A 10 nm titanium layer was first sputtered onto the silicon oxide transition bonding layer at a growth rate of 0.05 nm / s, followed by sputtering of a 70 nm titanium layer at a rate of 0.2 nm / s to form a titanium layer with a thickness of 80 nm. The titanium layer was then annealed at 200 °C for 80 min to obtain the photosensitive polyimide composite titanium film.

[0075] Example 3

[0076] This embodiment provides a photosensitive polyimide composite titanium film, which includes a photosensitive polyimide base film and an alumina transition bonding layer and a titanium layer sequentially stacked on the surface of the photosensitive polyimide base film. The surface of the photosensitive polyimide base film near the alumina transition bonding layer contains carboxyl groups, hydroxyl groups and amino groups.

[0077] The thickness of the alumina transition bonding layer is 5 nm, and the thickness of the titanium layer is 120 nm.

[0078] The photosensitive polyimide composite titanium film was prepared by the following method:

[0079] The photosensitive polyimide film was cured at 250°C for 0.5 h, then placed in a plasma treatment device and evacuated to a vacuum of 4 × 10⁻⁶. -6 Torr, using oxygen plasma and nitrogen plasma, is treated at 80W power for 30s and then vacuum baked at 200℃ for 20min to complete the surface treatment;

[0080] An aluminum oxide transition bonding layer with a thickness of 2 nm was deposited on the surface of the photosensitive polyimide film after surface treatment by ALD.

[0081] A 30 nm titanium layer was first sputtered onto the alumina transition bonding layer at a growth rate of 0.1 nm / s, followed by sputtering of a 90 nm titanium layer at a rate of 0.4 nm / s to form a titanium layer with a thickness of 120 nm. The titanium layer was then annealed at 300 °C for 40 min to obtain the photosensitive polyimide composite titanium film.

[0082] Example 4

[0083] The only difference between this embodiment and Embodiment 1 is that the thickness of the alumina transition bonding layer is 1 nm, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0084] Example 5

[0085] The only difference between this embodiment and Embodiment 1 is that the thickness of the alumina transition bonding layer is 8 nm; all other conditions and parameters are exactly the same as in Embodiment 1.

[0086] Example 6

[0087] The only difference between this embodiment and Embodiment 1 is that the titanium layer is sputtered at a speed of 0.3 nm / s, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0088] Comparative Example 1

[0089] The only difference between this comparative example and Example 1 is that the photosensitive polyimide film is not surface-treated; all other conditions and parameters are exactly the same as in Example 1.

[0090] Comparative Example 2

[0091] The only difference between this comparative example and Example 1 is that no alumina transition bonding layer is provided; all other conditions and parameters are exactly the same as in Example 1.

[0092] Comparative Example 3

[0093] The only difference between this comparative example and Example 1 is that the alumina transition bonding layer is replaced with a titanium oxide transition layer; all other conditions and parameters are exactly the same as in Example 1.

[0094] Comparative Example 4

[0095] The only difference between this comparative example and Example 1 is that the alumina transition bonding layer is replaced with a chromium transition layer; all other conditions and parameters are exactly the same as in Example 1.

[0096] Performance testing:

[0097] The peel strength of the photosensitive polyimide composite titanium films obtained in the examples and comparative examples was tested, and the results are shown in Table 1:

[0098] Table 1

[0099] Peel strength Example 1 14.6 N / cm Example 2 11.3 N / cm Example 3 12.4 N / cm Example 4 8.9 N / cm Example 5 9.8 N / cm Example 6 8.2 N / cm Comparative Example 1 6.6 N / cm Comparative Example 2 5.8 N / cm Comparative Example 3 7.6 N / cm Comparative Example 4 9.2 N / cm

[0100] As can be seen from Table 1, the peel strength of the photosensitive polyimide composite titanium film of the present invention can reach more than 8.2 N / cm, as obtained from Examples 1-6. By adjusting the preparation conditions, the peel strength of the photosensitive polyimide composite titanium film can reach more than 11.3 N / cm.

[0101] A comparison of Examples 1 and 4-5 shows that the thickness of the transition bonding layer in the photosensitive polyimide composite titanium film of the present invention affects its performance. When the thickness of the transition bonding layer is controlled between 2nm and 5nm, the performance of the photosensitive polyimide composite titanium film is better. If the thickness of the transition bonding layer is too small, it cannot completely cover the PI surface, and the bonding force is not sufficiently improved. If the thickness of the transition bonding layer is too large, a certain compressive stress is generated, which weakens the bonding force.

[0102] A comparison of Examples 1 and 6 reveals that the present invention first employs slow sputtering, allowing the titanium atoms to fully react with the oxygen atoms on the surface of the transition bonding layer, forming a continuous, pore-free, and chemically perfectly bonded initial titanium layer. This initial titanium layer covers and "passivates" the underlying transition bonding layer, providing a robust and stable substrate for subsequent rapid deposition. After the initial titanium layer is established, increasing the deposition rate allows for rapid deposition to the target thickness, ensuring production efficiency. The internal stress generated by rapid deposition is redistributed and buffered, reducing the likelihood of interface failure. Simultaneously, rapid deposition contributes to the formation of a better crystal structure, improving the quality of the resulting titanium layer.

[0103] As can be seen from the comparison between Example 1 and Comparative Examples 1-2, the present invention introduces polar functional groups on the surface of the photosensitive polyimide-based film. Strong chemical bonds exist between the polar functional groups and the transition bonding layer, resulting in extremely high bonding strength and significantly improving the structural stability of the film. The transition bonding layer interacts with highly reactive titanium atoms to form Ti-OM (M is silicon and / or aluminum) chemical bonds. These chemical bonds result in an interfacial bonding strength far exceeding the weak physical adsorption that might occur when titanium is directly deposited on an untreated photosensitive polyimide film. This significantly increases the bonding force between the titanium layer and the transition bonding layer, thereby obtaining a photosensitive polyimide composite titanium film with strong bonding.

[0104] As can be seen from the comparison of Example 1 and Comparative Examples 3-4, the material of the transition bonding layer in the photosensitive polyimide composite titanium film of the present invention is selective. The bonding strength of the present invention with the photosensitive polyimide base film and the titanium layer is significantly higher than that of titanium oxide (which has poor long-term stability) and metallic chromium (which is mainly bonded to the base film through van der Waals forces). This greatly improves the long-term reliability, environmental tolerance and stability of the prepared composite film. Compared with other functional oxides such as titanium oxide, the transition bonding layer of the present invention generally performs better and more reliable in terms of the universality of interface bonding and diffusion blocking ability. It is particularly suitable for high-end flexible electronics, aerospace and long-term implantable medical devices with demanding performance requirements.

[0105] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A photosensitive polyimide composite titanium film, characterized in that, The photosensitive polyimide composite titanium film includes a photosensitive polyimide base film and a transition bonding layer and a titanium layer sequentially stacked on the surface of the photosensitive polyimide base film; The surface of the photosensitive polyimide-based film near the transition layer contains polar functional groups.

2. The photosensitive polyimide composite titanium film as described in claim 1, characterized in that, The polar functional group includes any one or a combination of at least two of hydroxyl, carboxyl, or amino groups; Preferably, the material of the transition bonding layer includes silicon oxide and / or aluminum oxide.

3. The photosensitive polyimide composite titanium film as described in claim 1 or 2, characterized in that, The thickness of the transition bonding layer is 2nm~5nm; Preferably, the thickness of the titanium layer is 80nm~120nm.

4. A method for preparing a photosensitive polyimide composite titanium film as described in any one of claims 1-3, characterized in that, The preparation method includes the following steps: Surface treatment is performed on one side of the photosensitive polyimide-based film; A transition bonding layer is deposited on the surface of the photosensitive polyimide-based film after surface treatment; A titanium layer is sputtered onto the transition bonding layer to obtain the photosensitive polyimide composite titanium film.

5. The preparation method according to claim 4, characterized in that, The photosensitive polyimide-based film is cured before surface treatment; Preferably, the curing temperature is 200℃~250℃; Preferably, the curing time is 0.5h to 1.5h; Preferably, the surface treatment method includes plasma treatment and / or ion beam treatment; Preferably, the environmental vacuum degree of the surface treatment is 2×10⁻⁶. -6 Torr~4×10 -6 Torr; Preferably, the elements used in the surface treatment include oxygen and / or nitrogen; Preferably, the power of the surface treatment is 30W~80W; Preferably, the surface treatment time is 30s to 90s.

6. The preparation method according to claim 4 or 5, characterized in that, The surface treatment is followed by vacuum baking; Preferably, the temperature of the vacuum baking process is 150℃~200℃; Preferably, the vacuum baking process takes 20 to 40 minutes.

7. The preparation method according to any one of claims 4-6, characterized in that, The deposition of the transition bonding layer includes atomic layer deposition.

8. The preparation method according to any one of claims 4-7, characterized in that, The sputtered titanium layer includes a first sputtering and a second sputtering; Preferably, the growth rate of the first sputtering is 0.05 nm / s to 0.1 nm / s; Preferably, the thickness of the titanium layer obtained by the first sputtering is 10 nm to 30 nm; Preferably, the growth rate of the second sputtering is 0.2 nm / s to 0.4 nm / s; Preferably, the thickness of the titanium layer obtained by the second sputtering is 40 nm to 110 nm.

9. The preparation method according to any one of claims 4-8, characterized in that, The sputtered titanium layer is then annealed. Preferably, the annealing temperature is 200℃~300℃; Preferably, the annealing time is 40 min to 80 min; Preferably, the annealing atmosphere includes nitrogen and / or argon.

10. An application of the photosensitive polyimide composite titanium film as described in any one of claims 1-3, characterized in that, The photosensitive polyimide composite titanium film is used for any one or at least a combination of two of semiconductor packaging, flexible circuits, or microelectromechanical systems devices.