Method for producing a silicon dioxide film by means of a laser and device therefor

Abstract

The application provides a method and device for preparing a silicon dioxide film by a laser method, the method comprising: irradiating a film including polysilazane on a wafer with a laser with a wavelength less than or equal to 360 nm for a predetermined time in an environment of pure oxygen or a mixed gas containing oxygen, and obtaining a silicon dioxide film after the reaction is completed; the device comprising: a base plate, a sealing cover, a driving unit and a laser generator, the base plate and the driving unit are installed on a coating machine, the base plate is provided with a wafer bearing plate, the sealing cover is provided with an air inlet channel and an air outlet channel, the driving unit is used for driving the sealing cover to move so that the sealing cover cooperates with the base plate to form a sealed process chamber, the laser generator is installed on the sealing cover, and the wafer bearing plate is located on a laser light path of the laser generator. The application has the advantages of short conversion time, complete conversion, no need for high-temperature heating, and the device can be integrated with the coating machine, thereby improving the production capacity and reducing the process interval time.

Description

Technical Field

[0001] This invention belongs to the field of electronic semiconductor process technology, specifically relating to a method and apparatus for preparing silicon dioxide thin films by laser method. Background Technology

[0002] Polysilazane, as a material for spin-coated dielectric layers, can be transformed into a SiO2 dielectric layer through spin coating, film deposition, and other methods under certain conditions.

[0003] In recent years, with the continuous development of modern VLSI manufacturing, the importance of dielectric materials in device manufacturing processes has been increasing. SiO2 thin films possess excellent dielectric constant, corrosion resistance, moisture resistance, and insulation properties, making them widely used as trench filling materials in semiconductor processes. Conventional dielectric materials are prepared using thermal oxidation and vapor phase methods. However, these methods typically require high-temperature environments and are poorly effective at filling high aspect ratio trench structures, easily leading to voids. Therefore, the method of spin-coating polysilazane followed by annealing to convert it to SiO2 has gained increasing attention in recent years. In contrast, liquid-phase spin-coating solves, to some extent, the problem of bridging defects easily generated in subsequent processes.

[0004] Currently, the spin-on dielectric (SOD) materials commonly used in the semiconductor field are polyhydrosilazane (PHPS) and polymethylpolysilazane (PSZ). Due to the large volume shrinkage rate of PSZ, it has numerous pores, leading to high leakage current. Therefore, PHPS is conventionally used as a precursor to prepare high-quality SiO2 films. Current methods for converting polysilazane to SiO2 mainly include high-temperature treatment, ultraviolet photolysis, and a combination of ultraviolet and high-temperature treatment. High-temperature treatment is the most commonly used, but its disadvantages include the high temperature required for complete conversion (usually above 625℃), large volume shrinkage rate, and high internal stress in the material. Ultraviolet photolysis can be carried out at room temperature, but the reaction time at room temperature is usually more than 1 hour, and the conversion is incomplete. The combination of ultraviolet and high-temperature treatment produces films of better quality, but the conversion process is more complex.

[0005] Patent CN111052321A discloses a method for forming an insulating film, a substrate processing apparatus, and a substrate processing system. This patent employs a combination of ultraviolet photolysis and high-temperature processing. After ultraviolet photolysis, the reaction is carried out in a water vapor atmosphere at a temperature greater than 350°C. The advantage of this conversion method is that it results in low internal stress in the formed material. Although the conversion is complete, the process is relatively complex, and there should be as little time interval as possible between the ultraviolet light and the high-temperature baking. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus for preparing silicon dioxide thin films by laser method. The method of this invention not only has a short conversion time and complete conversion, but also does not require high temperature heating, thus saving costs. Moreover, the corresponding apparatus can be integrated with a coating machine, thereby increasing production capacity and reducing process interval time.

[0007] This invention provides a method for preparing silicon dioxide thin films using a laser method, characterized by comprising the following steps: irradiating a thin film on a wafer with a laser of wavelength less than or equal to 360 nm for a predetermined time in an environment of pure oxygen or a mixed gas containing oxygen, and obtaining a silicon dioxide thin film after the reaction is completed, wherein the material of the thin film includes polysilazane.

[0008] Furthermore, the polysilazane includes: perhydropolysilazane (PHPS) and polymethylpolysilazane (PSZ). Preferably, the polysilazane is perhydropolysilazane.

[0009] Furthermore, the laser source is a surface source.

[0010] Furthermore, the laser power is sufficient to penetrate the thin film without affecting the wafer substrate.

[0011] Furthermore, the mixed gas includes oxygen and an inert gas.

[0012] Furthermore, before laser irradiating the thin film, it is first purged with an inert gas, and then pure oxygen or a mixture containing oxygen is introduced.

[0013] Furthermore, the inert gas is nitrogen, argon, etc., and preferably, nitrogen is the inert gas.

[0014] Furthermore, the film is prepared by spin coating.

[0015] The present invention also provides an apparatus for preparing silicon dioxide thin films by laser method, installed inside a coating machine, for implementing the above-described method for preparing silicon dioxide thin films by laser method, characterized in that it includes: a chassis, installed on the coating machine, on which a wafer carrier plate is disposed; a sealing cover, on which an air inlet channel and an air outlet channel are disposed; a drive unit, installed on the coating machine, for driving the sealing cover to move toward or away from the chassis; and a laser generator, installed on the sealing cover, for emitting laser light. Under the drive of the drive unit, the sealing cover moves toward the chassis until the two are combined to form a sealed process chamber, the wafer carrier plate is located in the process chamber, and the wafer carrier plate is located in the laser beam path of the laser generator.

[0016] Furthermore, the apparatus for preparing silicon dioxide thin films by laser method also includes: a transfer unit mounted on a coating machine table, the transfer unit being used to transfer the wafer located at the spin coating area to the wafer carrier plate.

[0017] Furthermore, the apparatus for preparing silicon dioxide thin films by laser method also includes: a conversion unit disposed at the outlet of the laser emitted by the laser generator, used to convert the laser point source emitted by the laser generator into a laser surface source.

[0018] Furthermore, the sealing cover includes a first cover and a second cover, the first cover is disposed inside the second cover, there is a gap between the first cover and the second cover, and the air intake channel includes an air intake pipe disposed on the second cover and a plurality of air intake holes disposed on the first cover.

[0019] Furthermore, the plurality of air intake holes are evenly arranged on the side of the first cover away from the chassis, and one end of the exhaust channel is located on the side wall of the first cover and faces the end of the chassis.

[0020] The beneficial effects of this invention are: The laser method for preparing silicon dioxide thin films of the present invention uses laser irradiation of a thin film containing polysilazane. The laser generates a certain temperature on the wafer surface and inside the film layer, which can break the chemical bonds of polysilazane, causing Si to form dangling bonds, which further react with O2 in the mixed gas to generate SiO2. Laser irradiation not only provides the energy required for bond breaking, but also provides the heat required for conversion. The present invention not only has a short conversion time and complete conversion, but also does not require high-temperature heating. Moreover, the device corresponding to the method of the present invention can be integrated with the coating machine, thereby improving production capacity and reducing process interval time. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of this disclosure and are not intended to limit this disclosure.

[0022] Figure 1 The reaction principle diagram of laser conversion of SiO2 is shown; Figure 2 A flowchart illustrating the conversion of SOD thin film into SiO2 thin film is shown. Figure 3 A simplified structural diagram of an apparatus for preparing silicon dioxide thin films by laser method is shown; Figure 4 This diagram shows the effect of small-area transformation on a wafer; Figure 5 The infrared spectrum of the SOD thin film on the wafer in Example 9 is shown; Figure 6 The infrared spectrum of the SOD film converted to SiO2 film in Example 9 is shown; Figure 7 The infrared spectrum of the SOD film converted to SiO2 film in Example 13 is shown; Figure 8 The image shows a SEM image of the conversion of SOD film to SiO2 film in Example 9; Figure 9 The SEM image of the conversion of SOD film to SiO2 film in Example 13 is shown; Figure 10 The XRD pattern of the SOD film converted to SiO2 film in Example 9 is shown. Figure 11 The XRD pattern of the SOD film converted to SiO2 film in Example 13 is shown. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0024] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” indicate that the element or object preceding “comprising” or “including” encompasses the element or object listed following “comprising” or “including” and its equivalents, and do not exclude other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0025] This disclosure provides a method for preparing a silicon dioxide thin film using a laser method, comprising the following steps: irradiating a thin film on a wafer with a laser of wavelength less than or equal to 360 nm for a predetermined time in an environment of pure oxygen or a mixed gas containing oxygen, and obtaining a silicon dioxide thin film after the reaction is completed, wherein the material of the thin film includes polysilazane.

[0026] The reaction principle of converting a thin film containing polysilazane into a SiO2 thin film using a laser method is as follows: Figure 1 As shown: The laser generates a certain temperature on the wafer surface and inside the film layer, which can break the chemical bonds of polysilazane, causing Si to form dangling bonds, and further react with O2 in the air to generate SiO2.

[0027] The selection of the laser wavelength is calculated according to Planck's law (E=hv=hc / λ), where h is Planck's constant with a value of 6.626*10-34 J / s. SOD contains NH bonds, Si-H bonds, and Si-N bonds. Among them, the Si-N bond energy is the largest, at 84.83 kcal / mol. Therefore, to achieve bond breaking, the energy provided by the laser in the corresponding wavelength band must be greater than the bond energy of the Si-N bond. According to Planck's law, the laser wavelength cannot be greater than 360 nm. That is, laser sources with wavelengths below 360 nm can achieve this conversion process.

[0028] This disclosure provides a novel SOD-SiO2 conversion technology. Laser irradiation provides not only the energy required for bond breaking but also the heat required for conversion. Therefore, the requirements for the reaction environment and conditions are not so stringent. It can be carried out at room temperature and atmospheric pressure, avoiding high-temperature heating environments and saving costs. The conversion time is short and the conversion is complete. Moreover, the device corresponding to the method of this disclosure can be integrated with the coating machine, thereby increasing production capacity and reducing process interval time.

[0029] This disclosure also provides an apparatus for preparing silica thin films using a laser method, for implementing a method for preparing silica thin films using a laser method. The apparatus 100 for preparing silica thin films using a laser method is installed inside a coating machine.

[0030] Figure 3 A simplified structural diagram of an apparatus for preparing silicon dioxide thin films by laser method is shown.

[0031] like Figure 3 As shown, the apparatus 100 for preparing silicon dioxide thin films by laser method includes: a chassis 10, a sealing cover 20, a drive unit 30, a laser generator 40, and a transmission unit 50.

[0032] The chassis 10 is mounted on the glue coating machine platform, and a wafer carrier plate 11 is provided on the chassis 10. The wafer carrier plate 11 is used to support the wafer.

[0033] The sealing cover 20 is fitted to the chassis 10, forming a sealed process chamber when they mate, providing a reaction environment for the conversion of the polysilazane-containing thin film on the wafer into a SiO2 thin film. The wafer carrier 11 is located within the process chamber. The sealing cover 20 is provided with an inlet channel 21 and an exhaust channel 22. Fresh gas enters the process chamber through the inlet channel 21, and the gas inside the process chamber is exhausted through the exhaust channel 22.

[0034] In some examples, the sealing cover 20 includes a first cover 23 and a second cover 24, with the first cover 23 disposed within the second cover 24 and a gap between them. For example, both the first cover 23 and the second cover 24 are cylinders open at one end, with the diameter of the cross-section of the first cover 23 being smaller than the diameter of the cross-section of the second cover 24, forming a gap between them after the first cover 23 is disposed within the second cover 24. The air intake channel 21 includes at least one air intake pipe 211 disposed on the second cover 24 and multiple air intake holes 212 disposed on the first cover 23. For example, there are two air intake pipes 211, one for introducing oxygen and the other for introducing an inert gas when a mixed gas is introduced. The sealing cover 20 is provided with a gap and multiple air intake holes 231 to allow gas to be uniformly introduced into the process chamber.

[0035] In some examples, multiple air inlets 212 are evenly distributed on the side of the first cover 23 away from the chassis 10, i.e., multiple air inlets 212 are evenly distributed on the top surface of the first cover 23. One end of the exhaust channel 22 is located on the side wall of the first cover 23 and faces the end of the chassis 10, i.e., one end of the exhaust channel 22 is located at the lower end of the side wall of the first cover 23. The sealing cover 20 allows air to enter from the top and exit from the bottom, enabling the gas in the process chamber to be replaced.

[0036] In some examples, the first cover 23 and the second cover 24 are both made of transparent material to facilitate observation of the interior of the sealing cover 20.

[0037] The drive unit 30 is mounted on the glue coating machine platform. The drive unit 30 is used to drive the sealing cover 20 to move toward or away from the chassis. That is, the drive unit 30 drives the sealing cover 20 to move up and down. When the drive unit 30 drives the sealing cover 20 to move upward, the sealing cover 20 and the chassis 10 separate. When the drive unit 30 drives the sealing cover 20 to move downward, the sealing cover 20 and the chassis 10 cooperate to form a sealed process chamber.

[0038] The laser generator 40 is mounted on the sealing cover 20 and is used to emit laser light. The wafer carrier 11 is located in the laser light path of the laser generator 40, so when the wafer is placed on the wafer carrier 11, the laser light emitted by the laser generator 40 can irradiate the wafer.

[0039] In some examples, the laser generator 40 is mounted on top of the sealing cover 20.

[0040] In some examples, the apparatus 100 for laser-based preparation of silicon dioxide thin films further includes a conversion unit 60. The conversion unit 60 is located at the exit of the laser emitted by the laser generator 40. The conversion unit 60 converts the laser point source emitted by the laser generator 40 into a laser surface source, which can irradiate the entire surface of the wafer. It is understood that the conversion unit 60 is not essential. When it is necessary to achieve the entire surface of the SOD film converted into a silicon dioxide film after spin-coating SOD material onto the wafer, a surface source is selected, and the conversion unit 60 is required to convert the laser point source into a surface source. If only local irradiation of the SOD film on the wafer (small-area conversion) is desired, laser point source irradiation is selected, and the conversion unit 60 is not required. The point source irradiation point is more concentrated, providing high local heat energy, and the time required for complete conversion is shorter.

[0041] The transfer unit 50 is mounted on the coating machine. The transfer unit 50 is used to transfer the wafer located at the spin coating area to the wafer carrier plate 11. Specifically, after the robot arm of the coating machine takes out the wafer after spin coating with SOD material and drying, it places it on the transfer unit 50, and the transfer unit 50 transfers the wafer to the wafer carrier plate 11.

[0042] In some examples, the apparatus 100 for laser-based preparation of silica thin films also includes an online oxygen concentration detector (not shown) for measuring the oxygen concentration within the process chamber. Once the oxygen concentration detected by the online oxygen concentration detector stabilizes, it indicates that the purging inert gas has been completely replaced.

[0043] The operation of the laser method for preparing silicon dioxide thin films in the apparatus 100 is as follows: the drive unit 30 drives the sealing cover 20 to move upward, the sealing cover 20 and the chassis 10 separate, the robot arm of the coating machine removes the wafer with SOD film and places it on the transfer unit 50, the transfer unit 50 transfers the wafer to the wafer carrier plate 11, the drive unit 30 drives the sealing cover 20 to move downward, the sealing cover 20 and the chassis 10 cooperate to form a sealed process chamber, inert gas is first introduced into the process chamber through the air inlet channel 21 for purging, then pure oxygen or a mixed gas containing oxygen is introduced through the air inlet channel 21, and the gas in the process chamber is discharged from the process chamber through the exhaust channel 22. The online oxygen concentration detector detects the oxygen concentration in the process chamber. Once the detected oxygen concentration stabilizes (indicating that the inert gas purging has been completely replaced), the laser generator 40 is turned on to perform laser irradiation. After the laser irradiation has been performed for a predetermined time, the SOD on the wafer is completely converted into a silicon dioxide film. Then, the drive unit 30 drives the sealing cover 20 to move upward, the sealing cover 20 separates from the chassis 10, and the wafer is removed.

[0044] Example 1 like Figure 2 As shown, in step S1, SOD material is spin-coated onto the silicon wafer with silicon film 100 prepared in the previous process on the coating machine to form a layer of SOD liquid layer 101 (in this embodiment, the core film-forming material of SOD material is all-hydrogen polysilazane).

[0045] Step S2: The silicon wafer containing the SOD liquid layer 101 is baked on a hot plate at 150°C to evaporate the solvent of the SOD material spin-coated on the silicon wafer and obtain a wafer covered with an SOD film 102 after curing.

[0046] In step S3, the wafer prepared in step S2 is placed on the transfer unit 50 of the laser method for preparing silicon dioxide thin films. The transfer unit 50 transfers the wafer to the wafer carrier plate 11. After the sealing cover 20 and the chassis 10 are sealed together, nitrogen gas is first introduced for purging at a rate of 5 L / min. Then, a mixed gas with an oxygen concentration of 21% (the concentration of oxygen in the atmosphere) is introduced. The mixed gas includes oxygen and nitrogen, which enter from different inlet pipes 211. The oxygen inlet rate is 1 L / min, and the nitrogen inlet rate is 3.76 L / min. The oxygen concentration in the process chamber was calibrated using an online oxygen concentration detector. When the measured oxygen concentration was approximately 21%, it indicated that the purged nitrogen had been completely replaced and the oxygen concentration was stable. The laser power was then adjusted to 2.5W, and the laser generator 40 was turned on. The laser generator emitted a point source laser with a wavelength of 355nm. The conversion unit 60 converted the point source laser into a surface source of approximately 1mm*1mm. The laser irradiated... Figure 4A SiO2 film 103 was obtained by irradiating a small square (approximately 1mm x 1mm) on the SOD film on the wafer for 40 minutes. The laser generator 40 was then turned off, and the wafer was removed. The distance between the laser generator 40 and the wafer carrier plate 11 was 35cm.

[0047] Example 2 The same descriptions as in Example 1 are omitted in Example 2. The difference between Example 2 and Example 1 is that the laser power is 1.5W.

[0048] Example 3 The same descriptions as in Example 1 are omitted in Example 3. The difference between Example 2 and Example 1 is that the laser power is 2W.

[0049] Example 4 The same parts as in Example 1 are omitted in Example 4. The difference between Example 2 and Example 1 is that the laser power is 3W.

[0050] Example 5 The same descriptions as in Example 5 and Example 1 are omitted. The difference between Example 2 and Example 1 is that the laser power is 3.5W.

[0051] Example 6 The same descriptions as in Example 1 are omitted in Example 6. The difference between Example 6 and Example 1 is that the irradiation time is 5 minutes.

[0052] Example 7 The same descriptions as in Example 1 are omitted in Example 7. The difference between Example 7 and Example 1 is that the irradiation time is 10 minutes.

[0053] Example 8 The same descriptions as in Example 1 are omitted in Example 8. The difference between Example 8 and Example 1 is that the irradiation time is 20 minutes.

[0054] Example 9 The same descriptions as in Example 1 are omitted in Example 9. The difference between Example 9 and Example 1 is that the irradiation time is 60 minutes.

[0055] Example 10 The same descriptions as in Example 1 are omitted in Example 10. The difference between Example 10 and Example 1 is that the oxygen concentration is 50%, the oxygen intake rate is 1L / min, the nitrogen intake rate is 1L / min, and the irradiation time is 20min.

[0056] Example 11 The same descriptions as in Example 11 are omitted. The difference between Example 11 and Example 1 is that the oxygen concentration is 70%, the oxygen intake rate is 1L / min, the nitrogen intake rate is 0.43L / min, and the irradiation time is 20min.

[0057] Example 12 The same descriptions as in Example 11 are omitted. The difference between Example 12 and Example 1 is that the mixed gas is pure oxygen, that is, the oxygen concentration is 100%, the oxygen intake rate is 1L / min, and the irradiation time is 20min.

[0058] Example 13 like Figure 2 As shown, in step S1, SOD material is spin-coated onto the silicon wafer with silicon film 100 prepared in the previous process on the coating machine to form a layer of SOD liquid layer 101 (in this embodiment, the core film-forming material of SOD material is all-hydrogen polysilazane).

[0059] Step S2: The silicon wafer containing the SOD liquid layer 101 is baked on a hot plate at 150°C to evaporate the solvent of the SOD material spin-coated on the silicon wafer and obtain a wafer covered with an SOD film 102 after curing.

[0060] In step S3, the wafer prepared in step S2 is placed on the transfer unit 50 of the laser method for preparing silicon dioxide thin films. The transfer unit 50 transfers the wafer to the wafer carrier plate 11. After the sealing cover 20 and the chassis 10 are sealed together, argon gas is first introduced for purging at an argon gas inlet rate of 5 L / min. Then, a mixed gas with an oxygen concentration of 21% is introduced. The mixed gas includes oxygen and argon. Oxygen enters from one inlet pipe 211, and argon enters from another inlet pipe 211 at an oxygen inlet rate of 1 L / min. The nitrogen inlet rate is 3.76 L / min. The oxygen concentration in the process chamber was detected using an online oxygen concentration detector. When the measured oxygen concentration was approximately 21%, it was confirmed that the purging argon gas had been completely replaced and the oxygen concentration was stable. The laser power was then adjusted to 2.5W, and the laser generator 40 was turned on. The laser generator emitted a point source laser with a wavelength of 305nm. The conversion unit 60 converted the point source into a surface source to irradiate the SOD film on the wafer. After irradiation for 60 minutes, a SiO2 film 103 was obtained. The laser generator 40 was then turned off, and the wafer was removed.

[0061] The reaction conditions for each embodiment are shown in Table 1.

[0062] Table 1.

[0063] The wafers from Examples 1 to 13 were subjected to EDS testing, and the SiO2 conversion was determined by the Si-O ratio.

[0064] Examples 1 to 5 use different laser powers but are otherwise identical. The Si and O ratios in the thin films of each wafer are shown in Table 2.

[0065] Table 2.

[0066] As shown in Table 2, the Si / O ratio decreases with increasing laser power, and after reaching its peak, it increases with further increases in laser power. This indicates that the SiO2 conversion rate is related to the laser power; too low a laser power results in incomplete conversion, while too high a laser power can affect the wafer substrate. Therefore, when selecting the laser power, it should be sufficient to penetrate the SOD film without affecting the wafer substrate. It should be noted that in Examples 1 to 13, the laser power of 2.5W is sufficient to penetrate the SOD film without affecting the wafer substrate. This only applies to the 35cm distance between the laser generator 40 and the wafer carrier 11 in Examples 1 to 13. It does not mean that the laser power is fixed at 2.5W. The laser power is also related to the distance between the laser generator 40 and the wafer carrier 11. When the distance between the laser generator 40 and the wafer carrier 11 changes, the laser power should also change accordingly.

[0067] Examples 1, 6 to 9 involve different irradiation times but are the same under the same conditions. The Si and O ratio data in each wafer thin film are shown in Table 3.

[0068] Table 3.

[0069] According to the data in Table 3, the Si / O ratio decreases with increasing laser irradiation time. When the Si / O ratio reaches 1:2, it is completely converted into SiO2, and this time is the reaction time for SOD to be completely converted into SiO2 under this condition.

[0070] Examples 8, 10, and 12 involve different oxygen concentrations while other conditions remain the same. The Si and O ratios in the thin films of each wafer are shown in Table 4.

[0071] Table 4.

[0072] According to the data in Table 3, the Si / O ratio decreases as the oxygen concentration increases, indicating that the higher the oxygen concentration, the more complete the conversion.

[0073] In summary, the factors affecting the conversion of SOD thin film to SiO2 thin film are: laser power, oxygen concentration, and reaction time. The higher the oxygen concentration and the longer the irradiation time, the more complete the conversion of SOD thin film to SiO2 thin film. The laser power must be sufficient to penetrate the SOD thin film without affecting the wafer substrate. If the laser power is too low, the conversion will be incomplete, and if the laser power is too high, it will affect the wafer substrate.

[0074] In Example 13, the Si:O ratio was 33%:67% (i.e., 1:2), indicating that SOD had been completely converted into SiO2.

[0075] The SiO2 thin films obtained in Examples 9 and 13 were experimentally characterized.

[0076] The SiO2 film obtained in step S3 and the SOD (hydrogenated polysilazane) film obtained in step S2 were characterized by infrared spectroscopy.

[0077] Infrared Spectrum Analysis: The infrared spectrum of the SOD film obtained in step S2 in Example 9 is as follows. Figure 5 As shown, from Figure 5 From this, we can see that at 3371cm -1 NH stretching and bending vibration peaks were observed in the vicinity, with a peak at 2161 cm⁻¹. -1 Si-H stretching vibration peaks were observed in the vicinity, with a peak at 840 cm⁻¹. -1 Si-N characteristic peaks appeared on both sides; the infrared spectra of the SiO2 thin films obtained in step S3 in Examples 9 and 13 are as follows: Figure 6 , Figure 7 As shown in the figure, the characteristic peaks of Si-H, NH, and Si-N all disappear, with the peak at 1042 cm⁻¹ disappearing. -1 The presence of Si-O bond characteristic peaks at all locations indicates that, following step S3, the Si-H, NH, and Si-N chemical bonds in the perhydropolysilazane are broken, and Si-O bonds are formed, thus converting the perhydropolysilazane into SiO2.

[0078] The SiO2 films obtained in Examples 9 and 13 were subjected to SEM surface observation and XRD testing.

[0079] like Figure 8 , Figure 9 As shown, the SEM characterization results of Examples 9 and 13 both indicate that the wafer surface has been transformed into SiO2 particles. Since the crystallization state of SiO2 has a significant impact on its dielectric properties, it is desirable that the SiO2 obtained from SOD conversion is amorphous silicon dioxide, such as... Figure 10 , Figure 11As shown in the XRD pattern, the SiO2 thin films of Examples 9 and 13 do not have any visible diffraction peaks in the 0-90° range, indicating that the atomic arrangement is completely disordered and that amorphous silicon dioxide is generated. The amorphous nature of the generated SiO2 thin film contributes to the high barrier properties of ions and small molecules, which is beneficial to preventing leakage current under applied bias voltage.

[0080] Although this disclosure has been described with reference to exemplary embodiments, various changes and modifications may be suggested to those skilled in the art. This disclosure is intended to cover such changes and modifications that fall within the scope of the appended claims.

[0081] Nothing described in this disclosure should be construed as implying that any particular element, step, or function is an essential element that must be included within the scope of the claims. The scope of the patent subject matter is defined only by the claims.

Claims

1. A method for preparing silicon dioxide thin films using a laser method, characterized in that, Includes the following steps: In a pure oxygen or oxygen-containing mixed gas environment, a thin film on a wafer is irradiated with a laser with a wavelength of less than or equal to 360 nm for a predetermined time. After the reaction is completed, a silicon dioxide thin film is obtained, wherein the material of the thin film includes polysilazane.

2. The method for preparing silicon dioxide thin films by laser method according to claim 1, characterized in that, The laser source is a surface light source.

3. The method for preparing silicon dioxide thin films by laser method according to claim 1, characterized in that, The power of the laser is sufficient to penetrate the thin film without affecting the wafer substrate.

4. The method for preparing silicon dioxide thin films by laser method according to claim 1, characterized in that, The mixed gas includes oxygen and an inert gas.

5. The method for preparing silicon dioxide thin films by laser method according to claim 1, characterized in that, Before laser irradiation of the thin film, it is first purged with an inert gas, and then pure oxygen or a mixture containing oxygen is introduced.

6. The method for preparing silicon dioxide thin films by laser method according to claim 1, characterized in that, The film is prepared by spin coating.

7. An apparatus for preparing silicon dioxide thin films by laser method, installed inside a coating machine, characterized in that, include: A chassis is mounted on the glue coating machine platform, and a wafer carrier plate is provided on the chassis; A sealing cover, wherein an air intake channel and an exhaust channel are provided on the sealing cover; A drive unit, mounted on the glue applicator, is used to drive the sealing cover to move toward or away from the chassis; as well as A laser generator, mounted on the sealed cover, is used to emit a laser. Driven by the drive unit, the sealing cover moves toward the chassis until the two combine to form a sealed process chamber, the wafer carrier is located in the process chamber, and the wafer carrier is located on the laser path of the laser generator.

8. The apparatus for preparing silicon dioxide thin films by laser method according to claim 1, characterized in that, Also includes: A transfer unit, mounted on a coating machine table, is used to transfer the wafer located at the spin coating area to the wafer carrier plate.

9. The apparatus for preparing silicon dioxide thin films by laser method according to claim 1, characterized in that, Also includes: A conversion unit is disposed at the outlet of the laser emitted by the laser generator, and is used to convert the laser point source emitted by the laser generator into a laser surface source.

10. The apparatus for preparing silicon dioxide thin films by laser method according to claim 1, characterized in that, The sealing cover includes a first cover and a second cover, the first cover is disposed inside the second cover, and there is a gap between the first cover and the second cover. The air intake channel includes an air intake pipe disposed on the second cover and a plurality of air intake holes disposed on the first cover.

11. The apparatus for preparing silicon dioxide thin films by laser method according to claim 10, characterized in that, The plurality of air intake holes are evenly arranged on the side of the first cover away from the chassis, and one end of the exhaust channel is located on the side wall of the first cover and faces the chassis.

Images