A spin coating method

Abstract

The present invention provides a spin coating method, which comprises: providing a substrate; applying a spin coating agent on the substrate; spin coating the spin coating agent to form a spin coating film layer on the surface of the substrate; performing a first oscillation step; performing a baking step, and performing a second oscillation step at least during a part of the baking step to solidify the spin coating film layer. The present invention can improve the uniformity of the thickness of the spin coating film layer by adding the first oscillation step and the second oscillation step. The thickness uniformity of the spin coating film layer is improved from 7.02% to within 3%, and the method can also save the cost of using the spin coating agent.

Description

Technical Field

[0001] The invention relates to the field of spin coating, in particular to a spin coating method. Background Art

[0002] In the semiconductor manufacturing process, spin coating technology is widely used. Taking the photoresist coating process and planarization process as examples, the photolithography process is the core of the semiconductor manufacturing process. The photoresist coating process is an extremely important part of the photolithography process. The quality of the photoresist coating will directly affect the quality of the semiconductor device. Therefore, the photoresist coating process plays an important role.

[0003] With the continuous development of devices, higher and higher resolutions are required from a process perspective. In addition to better and more optimized exposure systems, improving resolution also requires better photoresist spreading performance and a flatter silicon wafer surface.

[0004] In the current spin coating method, the spin coating agent is pushed away to form "waves", and the "waves" cannot be completely eliminated, and are retained by the film during the baking process, forming an uneven surface.

[0005] Therefore, how to solve the above problems becomes an issue that needs to be addressed. Summary of the invention

[0006] In view of the problem of insufficient bonding strength of zirconia ceramic-plastic composites in the prior art, the present invention provides a spin coating method, which comprises:

[0007] providing a substrate;

[0008] applying a spin coating agent on the substrate;

[0009] Spin-coating the spin-coating agent to form a spin-coated film layer on the surface of the substrate;

[0010] performing a first oscillation step;

[0011] A baking step is performed, and a second oscillation step is performed at least during a portion of the baking step to cure the spin-on film layer.

[0012] Optionally, the first oscillation step and the second oscillation step adopt an ultrasonic oscillation process.

[0013] Optionally, the oscillation frequency of the first oscillation step is greater than the oscillation frequency of the second oscillation step.

[0014] Optionally, the duration of the first oscillation step is 17s-23s; and / or

[0015] The frequency of the first oscillation step is 0.5 KHz-3.5 KHz.

[0016] Optionally, the duration of the second oscillation step is 165s-195s; and / or

[0017] The frequency of the second oscillation step is 0.1 KHz-0.5 KHz.

[0018] Optionally, a deep trench is formed in the substrate, and the method further comprises a step of filling the deep trench with the spin coating agent.

[0019] Optionally, the method comprises:

[0020] Spin-coating the spin-coating agent, and when the thickness of the spin-coating agent on the substrate is higher than 30% of the target thickness, stopping the rotation and performing a first oscillation step;

[0021] The first oscillation step is stopped and the spin coating agent is continued to be spin coated to the target thickness.

[0022] Optionally, the second oscillation step is performed throughout the baking step to solidify the spin-coated film layer; and / or the baking step includes a plurality of baking sub-steps performed sequentially, and the baking temperatures of the plurality of baking sub-steps are gradually increased.

[0023] Optionally, the baking step includes a first baking step, a second baking step and a third baking step performed sequentially;

[0024] The first baking step has a first baking temperature, the second baking step has a second baking temperature, the third baking step has a third baking temperature, the first baking temperature is lower than the second baking temperature, and the second baking temperature is lower than the third baking temperature.

[0025] Optionally, the first baking temperature ranges from 70 degrees Celsius to 80 degrees Celsius;

[0026] The second baking temperature ranges from 95 degrees Celsius to 100 degrees Celsius;

[0027] The first baking temperature ranges from 107 degrees Celsius to 113 degrees Celsius.

[0028] Optionally, the baking time of the first baking step is 55s-65s; and / or

[0029] The baking time of the second baking step is 55s-65s; and / or

[0030] The baking time of the third baking step is 55s-65s.

[0031] Optionally, the viscosity of the spin coating agent is greater than 100 CP.

[0032] Optionally, the viscosity of the spin coating agent ranges from 3000 CP to 15000 CP.

[0033] Optionally, the spin-coating agent comprises polyimide spin-coating agent.

[0034] In order to solve the existing technical problems, the present invention provides a spin coating method, in which a first oscillation step and a second oscillation step are independently added before the baking step after spin coating and during the baking step, and the uniformity of the thickness of the spin-coated film layer can be improved by adding the first oscillation step and the second oscillation step. The thickness uniformity of the spin-coated film layer is improved from 7.02% to within 3%, and the method can also save the cost of using a spin coating agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The following drawings of the present invention are used as part of the present invention for understanding the present invention. The drawings show embodiments of the present invention and their descriptions, and are used to explain the device and principle of the present invention. In the drawings,

[0036] Figure 1 Schematic diagram of a spin coating method according to an embodiment of the present invention;

[0037] Figure 2 is a schematic flow chart of a spin coating method according to another embodiment of the present invention;

[0038] Figure 3 Schematic diagram of the corresponding relationship between the spin coating uniformity (u%) and the ultrasonic oscillation frequency during the spin coating process in one embodiment of the present invention;

[0039] Figure 4 Schematic diagram of the corresponding relationship between the spin coating uniformity (u%) and the ultrasonic oscillation frequency during the baking process in one embodiment of the present invention;

[0040] Figure 5 It is a schematic diagram of the effect of uniformity and step coverage of the spin-coated film layer obtained by the spin-coating method in the prior art;

[0041] Figure 6 Schematic diagram of the effects of uniformity and step coverage of a spin-coated film layer obtained by a spin-coating method in one embodiment of the present invention. DETAILED DESCRIPTION

[0042] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0043] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0044] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0045] Spatially relative terms such as "under," "below," "below," "under," "above," "above," etc., may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0046] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0047] In order to fully understand the present invention, a detailed structure will be presented in the following description to illustrate the technical solution proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0048] With the continuous development of semiconductor technology, semiconductor devices are developing towards small size and high integration, which leads to higher and higher graphic resolution, larger aspect ratio and more and more complex steps. In order to obtain better process effects, high viscosity spin coating agents are derived, most of which have a viscosity of more than 100CP. IGBT, a power device widely used in electric vehicles and home appliances, requires a chemical polyimide with a viscosity far greater than 100CP (usually 3600CP). When the existing spin coating method is used to spin-coat high viscosity spin coating agents, the disadvantage of uneven coating will be magnified.

[0049] Due to the increase in the viscosity of the spin coating agent, the spin coating agent is pushed away during the low speed spin coating process to form "waves", such as Figure 5 As shown, the high viscosity and low fluidity of the spin-coated agent will result in the "waves" being unable to be completely eliminated, and then being retained by the film during the baking process, forming an uneven surface.

[0050] In order to solve the above problems, the present application provides a spin coating method, such as Figure 1 As shown, the spin coating method comprises:

[0051] Step S1: providing a substrate;

[0052] Step S2: applying a spin coating agent on the substrate;

[0053] Step S3: spin-coating the spin-coating agent to form a spin-coated film layer on the surface of the substrate;

[0054] Step S4: performing a first oscillation step;

[0055] Step S5: performing a baking step, and performing a second oscillation step at least during a part of the baking step to solidify the spin-coated film layer.

[0056] The method described in this application is described in detail below with reference to the accompanying drawings. Figure 3 Schematic diagram of the corresponding relationship between the spin coating uniformity (u%) and the ultrasonic oscillation frequency during the spin coating process in one embodiment of the present invention; Figure 4 Schematic diagram of the corresponding relationship between the spin coating uniformity (u%) and the ultrasonic oscillation frequency during the baking process in one embodiment of the present invention; Figure 6 Schematic diagram of the effects of uniformity and step coverage of a spin-coated film layer obtained by a spin-coating method in one embodiment of the present invention.

[0057] Specifically, in step S1, the substrate may be any flat surface that needs to be spin-coated with a spin coating agent. In the present application, in the semiconductor field, the substrate may be a substrate, such as a semiconductor substrate.

[0058] In a specific embodiment, the substrate can be at least one of the following materials: silicon, silicon on insulator (SOI), stacked silicon on insulator (SSOI), stacked silicon germanium on insulator (S-SiGeOI), and silicon germanium on insulator (SiGeOI), etc.

[0059] Optionally, various patterns of semiconductor devices may be further formed in the substrate, and the shapes of the patterns are not limited to a certain one.

[0060] For example, in one embodiment of the present application, a pattern of deep grooves is formed on the substrate, such as Figure 6 shown.

[0061] In the step S2, before applying the spin coating agent on the substrate, the method further includes performing surface pretreatment on the substrate.

[0062] In one embodiment of the present application, Figure 2 As shown, the substrate is a silicon wafer, and the surface of the silicon wafer is pretreated before the spin coating agent is added.

[0063] The surface pretreatment may be at least one of thinning, planarization or polishing processes to make the surface of the substrate smoother and prevent the uniformity of the spin-coated film from being affected in subsequent steps.

[0064] For example, in one embodiment of the present application, the surface of the substrate is chemically and mechanically planarized. The role of planarization technology in the entire semiconductor manufacturing process is to flatten the undulating dielectric layer appearance of the silicon wafer surface, thereby bringing higher graphic resolution of the photolithography process, better uniformity of the metal deposition process and metal etching morphology. For example, the planarization technology between metal layers of the process above 0.35um often chooses spin on glass coating (SOG), which uses the principle of spin coating to achieve the purpose of local planarization.

[0065] In the present application, the application may be dripping or spraying, which is not limited here. In one embodiment of the present application, a spin coating agent is dripped on the substrate.

[0066] After the substrate is subjected to surface pretreatment, a spin coating agent is dripped onto the substrate. In the present application, the viscosity of the spin coating agent is greater than 100 CP.

[0067] In the present application, the spin coating agent is a high-viscosity spin coating agent, for example, the viscosity of the spin coating agent ranges from 3000CP to 15000CP.

[0068] In one embodiment of the present application, the spin coating agent includes polyimide spin coating, and the viscosity of the spin coating agent is approximately 3600 CP.

[0069] In this step, a spin coating agent flows out from the tip of a nozzle in a spin coater and is dripped onto the surface of a rotating substrate. The substrate is supported by a rotatable support device.

[0070] In one embodiment of the present application, in the spin coater, the nozzle is connected to a cylinder filled with a spin coating agent. Air pressure (nitrogen, etc.) is applied to the cylinder to form a structure in which a certain amount of the spin coating agent flows out at a certain speed. Thereby, a structure is formed in which a specified amount of the spin coating agent can be dripped onto the surface of the substrate within a specified time by controlling the opening and closing of the air pressure. A check valve can be provided at the connection between the cylinder and the nozzle to prevent dripping.

[0071] The spin coating agent is discharged from the nozzle tip under the above conditions and dropped onto the rotating substrate surface. The spin coating agent dropped onto the substrate surface is spread on the substrate surface under the centrifugal force generated by the rotation of the substrate.

[0072] Specifically, in this step, in order to prevent the high viscosity spin coating agent from solidifying during the process of dripping the spin coating agent, the substrate is rotated at a low speed during the process of dripping the spin coating agent so that the spin coating agent is pushed at a low speed on the surface of the substrate to prevent the spin coating agent from solidifying to form protrusions.

[0073] The rotation speed of the substrate during the process of dripping the spin coating agent is 700-800 R / min. The rotation speed of the substrate can be selected according to the viscosity of the spin coating agent, and is not limited to this example.

[0074] In step S3, after the spin coating agent is dripped, the rotation speed of the substrate is increased, and the spin coating agent dripped onto the surface of the substrate is uniformly extended under the action of the centrifugal force generated by the rotation of the substrate, thereby obtaining a coating film with uniform thickness on the surface of the substrate.

[0075] Specifically, in this step, the rotation speed of the substrate is in the range of 1000-1500 R / min.

[0076] In this step, the method includes: spin-coating the spin-coating agent, and when the thickness of the spin-coating agent spread on the substrate is higher than 30% of the target thickness, stopping the rotation and executing the first oscillation step in step S4, in which oscillation is performed when a certain thickness of the spin-coating agent is spread, so that a smooth surface can be obtained more easily, thereby making the final spin-coated film layer have good uniformity; then stopping the first oscillation step and continuing the spin coating until the expected thickness is reached.

[0077] In step S4, in order to make the thickness of the spin-coated agent on the substrate more uniform, the high-frequency energy generated by oscillation in the first oscillation step will generate pressure waves during the transmission process, thereby causing the solvent in the spin-coated agent to flow to obtain a better spin coating and spreading effect.

[0078] Wherein, the first oscillation step may adopt an ultrasonic oscillation process.

[0079] In one embodiment of the present application, the duration of the first oscillation step is 17s-23s.

[0080] The frequency of the first oscillation step is 0.5 KHz-3.5 KHz, and the oscillation frequency of the spin coating process and the spin coating uniformity are approximately linearly related within the oscillation frequency range.

[0081] In one embodiment of the present application, a polyimide spin coating agent with a viscosity of 3000CP is spin-coated on a 6-inch wafer as an example, the ultrasonic oscillation time of the baking process is set to 60S, the frequency is set to 0.1KHz, and the ultrasonic time of the spin coating process is set to 20S. The ultrasonic oscillation frequency is used as a variable to study the corresponding relationship between the spin coating uniformity (u%) and the ultrasonic oscillation frequency of the spin coating process. The results are shown in Table 1:

[0082] Table 1 Correspondence between spin coating uniformity (u%) and ultrasonic oscillation frequency during spin coating

[0083]

[0084] Wherein, the spin coating uniformity u% = (maximum value - minimum value) / average value / 2×%, the linear relationship between the spin coating uniformity (u%) and the ultrasonic oscillation frequency during the spin coating process is as follows: Figure 3 As shown, it can be known from the above table and the linear graph that when the conditions of the baking step are fixed, when the oscillation frequency of the first oscillation step is 0.5KHz-3.5KHz, the oscillation frequency of the spin coating process and the spin coating uniformity are roughly linearly related within the ultrasonic oscillation frequency range.

[0085] In this step, the oscillation frequency is set to 0.5KHz-3.5KHz. The first oscillation step can obtain a better spin coating and spreading effect by generating pressure waves through high-frequency energy to make the solvent in the spin coating agent flow, so that the spin coating agent can flow further, thereby eliminating the thickness "waves" caused by high viscosity and low fluidity during the spin coating process.

[0086] Furthermore, in this step, the high frequency energy of the first oscillation step enables the spin coating agent to better fill the deep grooves in the substrate to improve the poor step coverage, and finally obtain a flatter surface and a better step coverage morphology, such as Figure 6 As shown, the deep trench can be completely filled and the generation of voids can be avoided by the method.

[0087] In the step S5, during the baking process, the frequency of the second oscillation step is reduced and the time is prolonged, for example, the time of the second oscillation step is 165s-195s; and / or the frequency of the second oscillation step is 0.1KHz-0.5KHz.

[0088] In the second oscillation step, the baking process is mainly to remove the spin coating agent solvent. As the baking progresses, the fluidity of the spin coating agent deteriorates. By extending the time of the second oscillation step, the uniformity is further improved and the generation of wavy defects is prevented. Therefore, ultrasonic oscillation is performed throughout the baking process.

[0089] In addition, the oscillation frequency of the second oscillation step is not set arbitrarily. If the frequency is too low, the fluidity of the spin-coated agent will deteriorate during baking, and the thickness uniformity will deteriorate. However, if ultrasonic oscillations of too high a frequency are used in the baking process, pressure waves with too high energy will be generated, causing the solvent to flow violently, and ultimately a spike effect will be formed on the coating surface as the spin-coated agent solidifies.

[0090] The second oscillation step may be performed throughout the entire baking process or any period of time, which is not limited here.

[0091] In one embodiment of the present application, the second oscillation step is performed throughout the baking step to solidify the spin-coated film layer.

[0092] In one embodiment of the present application, a polyimide spin coating agent with a viscosity of 3000CP is spin-coated on a 6-inch wafer as an example, the ultrasonic oscillation time of the spin coating process is set to 20S, the frequency is set to 0.1KHz, and the baking time is set to 60S. The ultrasonic oscillation frequency of the baking process is used as a variable to study the corresponding relationship between the spin coating uniformity (u%) and the ultrasonic oscillation frequency of the baking process. The results are shown in Table 2:

[0093] Table 2 Correspondence between spin coating uniformity (u%) and ultrasonic oscillation frequency during baking process

[0094]

[0095] Wherein, the spin coating uniformity u% = (maximum value - minimum value) / average value / 2 ×%, the linear relationship between the spin coating uniformity (u%) and the ultrasonic oscillation frequency of the baking process is as follows: Figure 4 As shown, it can be known from the above table and the linear graph that when the conditions of the spin coating step are fixed, when the oscillation frequency of the second oscillation step is 0.1KHz-0.5KHz, the oscillation frequency of the spin coating process and the spin coating uniformity are roughly linearly related within the ultrasonic oscillation frequency range.

[0096] In this step, the second oscillation frequency is set to 0.1 KHz-0.5 KHz. The second oscillation step can avoid the formation of a peak effect on the coating surface during the baking step, thereby obtaining a smoother surface.

[0097] In one embodiment of the present application, the polyimide spin coating agent with a viscosity of 3000CP in the spin coating agent range, after adding the first oscillation step and the second oscillation step, the uniformity within the chip after spin coating will be improved from 7.02% to within 3%, and the coverage of the step will be better, such as Figure 6 As shown, the effect is better than that in the prior art Figure 5 The effect shown is greatly improved.

[0098] The first oscillation step and the second oscillation step can adjust the oscillation frequency and oscillation time respectively, and the ultrasonic oscillation frequency and oscillation time of the two stages can be adjusted according to different viscosities of the spin coating agent.

[0099] In one embodiment of the present application, Figure 2 As shown, the baking step includes a first baking step, a second baking step and a third baking step which are performed in sequence, and the spin coating agent is solidified through the three baking steps.

[0100] Among them, the first baking step has a first baking temperature to obtain a first film layer; the second baking step has a second baking temperature to obtain a second film layer; the third baking step has a third baking temperature to obtain a third film layer; wherein the first film layer, the second film layer and the third film layer are film layers in different states during the curing of the spin-coated film layer.

[0101] The first baking temperature is lower than the second baking temperature, and the second baking temperature is lower than the third baking temperature. Optionally, the first baking temperature is in the range of 70 degrees Celsius to 80 degrees Celsius; the second baking temperature is in the range of 95 degrees Celsius to 100 degrees Celsius; and the first baking temperature is in the range of 107 degrees Celsius to 113 degrees Celsius.

[0102] In the present application, the baking step is divided into three baking steps, and the baking temperature is gradually increased to better achieve the curing of the spin-coated agent and improve the flatness of the spin-coated film layer to prevent the problem that the surface has been cured but the interior has not been cured.

[0103] Further, the baking time of the first baking step is 55s-65s; and / or

[0104] The baking time of the second baking step is 55s-65s; and / or

[0105] The baking time of the third baking step is 55s-65s.

[0106] In order to solve the technical problem of the present application, a spin coating method is provided in the present application, in which an oscillation process is added independently before baking after spin coating and during baking, and the oscillation frequency and oscillation time of the two stages can be adjusted separately; by adding the first oscillation step and the second oscillation step, the thickness uniformity of the spin-coated film layer can be improved. For example, the thickness uniformity of the spin-coated film layer will be improved from 7.02% to within 3%. In addition, compared with the spin coating process that improves the spin coating spreading effect by high rotation speed, the new spin coating process of the present invention will save the cost of using the spin coating agent.

[0107] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present invention thereto. Various changes and modifications may be made therein by one of ordinary skill in the art without departing from the scope and spirit of the present invention. All such changes and modifications are intended to be included within the scope of the present invention as required by the appended claims.

[0108] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0109] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed.

[0110] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0111] Similarly, it should be understood that in order to streamline the present invention and help understand one or more of the various inventive aspects, in the description of the exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present invention should not be interpreted as reflecting the following intention: the claimed invention requires more features than the features explicitly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby expressly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present invention.

[0112] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0113] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0114] It should be noted that the above embodiments illustrate rather than limit the invention, and that those skilled in the art may devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets shall not be construed as a limitation on the claims. The invention may be implemented by means of hardware comprising a number of different elements and by means of a suitably programmed computer. In a unit claim enumerating a number of means, several of these means may be embodied by the same hardware item. The use of the words first, second, and third, etc., does not indicate any order. These words may be interpreted as names.

Claims

1. A spin coating method, characterized in that: The spin coating method comprises: providing a substrate; applying a spin coating agent on the substrate; Spin-coating the spin-coating agent to form a spin-coated film layer on the surface of the substrate; Performing a first oscillation step, wherein the frequency of the first oscillation step is 0.5 KHz-3.5 KHz; A baking step is performed, and a second oscillation step is performed at least during a portion of the baking step, wherein the frequency of the second oscillation step is 0.1 KHz-0.5 KHz, so as to cure the spin-coated film layer.

2. The spin coating method according to claim 1, characterized in that The first oscillation step and the second oscillation step employ an ultrasonic oscillation process.

3. The spin coating method according to claim 1, characterized in that The oscillation frequency of the first oscillation step is greater than the oscillation frequency of the second oscillation step.

4. The spin coating method according to claim 1, characterized in that The time of the first oscillation step is 17s-23s.

5. The spin coating method according to claim 1, characterized in that The time of the second oscillation step is 165s-195s.

6. The spin coating method according to claim 1, characterized in that A deep trench is also formed in the substrate, and the method further includes a step of filling the deep trench with the spin coating agent.

7. The spin coating method according to claim 1, characterized in that The method comprises: Spin-coating the spin-coating agent, and when the thickness of the spin-coating agent on the substrate is higher than 30% of the target thickness, stopping the rotation and performing a first oscillation step; The first oscillation step is stopped and the spin coating agent is continued to be spin coated to the target thickness.

8. The spin coating method according to claim 1, characterized in that: The second oscillation step is performed during the entire baking step to solidify the spin-coated film layer; and / or the baking step includes a plurality of baking sub-steps performed in sequence, and the baking temperatures of the plurality of baking sub-steps are gradually increased.

9. The spin coating method according to claim 8, characterized in that: The baking step includes a first baking step, a second baking step and a third baking step which are performed sequentially; The first baking step has a first baking temperature, the second baking step has a second baking temperature, the third baking step has a third baking temperature, the first baking temperature is lower than the second baking temperature, and the second baking temperature is lower than the third baking temperature.

10. The spin coating method according to claim 9, characterized in that: The first baking temperature ranges from 70 degrees Celsius to 80 degrees Celsius; The second baking temperature ranges from 95 degrees Celsius to 100 degrees Celsius; The third baking temperature ranges from 107 degrees Celsius to 113 degrees Celsius.

11. The spin coating method according to claim 9, characterized in that: The baking time of the first baking step is 55s-65s; and / or The baking time of the second baking step is 55s-65s; and / or The baking time of the third baking step is 55s-65s.

12. The spin coating method according to any one of claims 1 to 11, characterized in that: The viscosity of the spin coating agent is greater than 100 CP.

13. The spin coating method according to claim 12, characterized in that: The viscosity of the spin coating agent ranges from 3000 CP to 15000 CP.

14. The spin coating method according to claim 12, characterized in that: The spin coating agent includes polyimide.

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