Megasonic cleaning effect evaluation method based on silicon dioxide film

Abstract

The invention discloses a megasonic cleaning effect evaluation method based on a silicon dioxide film, and relates to the field of megasonic cleaning effect evaluation, and the method comprises the following steps: preparing a silicon dioxide film sample; placing the silicon dioxide film sample in a megasonic cleaning tank for megasonic cleaning; obtaining characterization data of the silicon dioxide film sample before and after cleaning; and evaluating the megasonic cleaning effect according to the characterization data of the silicon dioxide film sample before and after cleaning. According to the method, the megasonic cleaning effect can be quickly and accurately evaluated at low cost.

Description

Technical Field

[0001] The present application relates to the field of megasonic cleaning effect evaluation, and in particular to a method for evaluating the megasonic cleaning effect based on a silicon dioxide film. Background Art

[0002] Megasonic cleaning is widely used in wet cleaning of integrated circuits, optical components, medical devices, etc. Using megasonic cleaning technology to remove surface particles is an important part of the integrated circuit manufacturing process and has a significant impact on product yield and device reliability.

[0003] There are two methods to evaluate the effect of megasonic cleaning: direct and indirect. The equipment used in the direct method is expensive, and its test results will also be affected by factors such as surface defects and surface roughness. The indirect method cannot evaluate the uniformity of surface cleaning. Summary of the invention

[0004] The purpose of the present application is to provide a method for evaluating the megasonic cleaning effect based on a silicon dioxide film, which can evaluate the megasonic cleaning effect in a low-cost, fast and accurate manner.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] A method for evaluating the megasonic cleaning effect based on silicon dioxide film, comprising:

[0007] preparing silicon dioxide thin film samples;

[0008] Placing the silicon dioxide film sample in a megasonic cleaning tank for megasonic cleaning;

[0009] Obtaining characterization data of the silicon dioxide film sample before and after cleaning; the characterization data includes a transmission spectrum, a surface optical image, an atomic force image, and a thickness of the silicon dioxide film;

[0010] The megasonic cleaning effect was evaluated based on the characterization data of the silica film samples before and after cleaning.

[0011] According to the specific embodiments provided in this application, this application has the following technical effects:

[0012] The present application provides a method for evaluating the effect of megasonic cleaning based on silicon dioxide film, and obtains the characterization data (transmission spectrum, surface optical image, atomic force image and thickness of silicon dioxide film) of the prepared silicon dioxide film sample before and after cleaning. The characterization data of the silicon dioxide film sample before and after cleaning can be used to determine the influence of the cleaning fixture on the acoustic field shielding, and obtain the state of the film layer peeling on the substrate surface, the particle removal efficiency and other parameters, so as to realize the evaluation of the effect of megasonic cleaning. The above method provided by the present application is low in cost, fast in speed and has accurate evaluation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 A schematic diagram of a flow chart of a method for evaluating the megasonic cleaning effect based on a silicon dioxide film provided in one embodiment of the present application;

[0015] Figure 2 This is a comparison chart of transmission spectra of silicon dioxide films;

[0016] Figure 3 This is a comparison of the surface optical images of the silicon dioxide film sample before and after cleaning;

[0017] Figure 4 This is a comparison of low-magnification surface optical images of the silicon dioxide film sample before and after cleaning. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0020] In an exemplary embodiment, Figure 1 As shown, a method for evaluating the megasonic cleaning effect based on a silicon dioxide film is provided, comprising the following steps S1 to S4. Among them:

[0021] S1: Preparation of silicon dioxide thin film samples.

[0022] The silicon dioxide nanoparticles are coated on a substrate to prepare a silicon dioxide thin film sample, and the silicon dioxide thin film sample is prepared by dipping, pulling, spin coating, etc. The substrate suitable for coating the silicon dioxide nanoparticles is a silicon wafer, quartz or silicate glass, etc.

[0023] S2: placing the silicon dioxide film sample in a megasonic cleaning tank for megasonic cleaning.

[0024] S3: Obtain characterization data of the silicon dioxide film sample before and after cleaning. The characterization data include: transmission spectrum, surface optical image, atomic force image and silicon dioxide film thickness.

[0025] Place the silicon dioxide film sample in a megasonic cleaning tank, take it out after a certain period of megasonic cleaning, dry it naturally, and then characterize the film using instruments such as a spectrophotometer, optical microscope, and atomic force microscope to obtain transmission spectra, surface optical images, and atomic force images. The thickness of the silicon dioxide film can be tested using an ellipsometer.

[0026] S4: Evaluate the megasonic cleaning effect based on the characterization data of the silica film samples before and after cleaning.

[0027] The peeling condition of the silica film is determined by comparing the transmission spectra of the silica film sample before and after cleaning; the shielding condition of the silica film sample by the cleaning fixture is determined by comparing the surface optical images of the silica film sample before and after cleaning; the removal efficiency of the silica film is determined by comparing the depth and width of pits or grooves in the atomic force images of the silica film sample before and after cleaning; or the removal efficiency of the silica film is determined by comparing the thickness of the silica film before and after cleaning the silica film sample.

[0028] In a specific embodiment, for quartz or silicate glass substrates, the technical solution is as follows:

[0029] First, the substrate is cleaned by ultrasonic cleaning. The cleaning steps are as follows: the substrate is ultrasonically cleaned in alkaline cleaning solution and pure water for 30 minutes, the ultrasonic frequency is 40kHz to 120kHz, and then slowly pulled and dehydrated in hot water. The pulling speed of slow pulling and dehydration is (0.5-1.5) mm / s, and the hot water temperature is (45-60) ° C. The synthesis of nano-silica particles adopts a double precursor base-catalyzed hydrolysis route, that is, ethyl orthosilicate and methyltriethoxysilane are used as precursors, ethanol is used as solvent, a certain amount of ammonia and water are added, mixed evenly, sealed at room temperature for aging, and can be used after being placed for 7 days. The aged silica colloid is used to pull the coating on the quartz or silicate glass substrate, and then the prepared silica film sample is clamped firmly and placed in the megasonic cleaning tank for cleaning. The cleaning time is adjusted according to the megasonic frequency and power. After the cleaned sample is naturally dried, it is characterized.

[0030] The transmission spectrum of the silicon dioxide film sample is tested by a spectrophotometer. By comparing the spectral curves of the transmission spectrum, the overall peeling condition of the silicon dioxide film can be obtained, such as Figure 2By scanning the entire surface of the silicon dioxide film sample with an optical microscope, a surface optical image with stripe distribution characteristics can be obtained. The stripe distribution can reflect the strength distribution of the megasonic field in space, such as Figure 3 The propagation of megasonic sound field has strong directionality. Object blocking will significantly weaken the sound field intensity. By comparing the surface optical images of various areas on the surface of the silicon dioxide film sample, it can be determined which areas are significantly blocked by the cleaning fixture, so as to make corresponding optimization designs to reduce the fixture blocking effect, such as Figure 4 As shown. By scanning the sample surface with an atomic force microscope, an atomic force image with pits or grooves on the surface can be obtained. By testing the depth and width parameters of the pits or grooves, the removal efficiency of the silicon dioxide film can be obtained. In addition, by using a strong light to illuminate the sample surface in a dark room, the stripe distribution on the surface of the silicon dioxide film sample can be directly observed visually, which can be used to qualitatively judge the effect of megasonic cleaning.

[0031] In a specific embodiment, for a silicon substrate, the technical solution is as follows:

[0032] The substrate was ultrasonically cleaned in acetone, anhydrous ethanol, and distilled water for 15 minutes, with an ultrasonic frequency of 40kHz to 120kHz, and then slowly pulled in anhydrous ethanol for dehydration and drying. The pulling speed of slow pulling and dehydration is (0.5-1.5) mm / s. Two kinds of nano-silicon dioxide particles are needed to coat the silicon substrate, which are marked as colloid 1 and colloid 2 respectively. Colloid 1 is synthesized with tetraethyl orthosilicate as the precursor and ethanol as the solvent. A certain amount of ammonia water is added, mixed evenly, and sealed at room temperature for aging. It can be used after being placed for 3 days. The synthesis of colloid 2 adopts the dual precursor base-catalyzed hydrolysis route as described above. The cleaned silicon wafer is placed in colloid 1 to pull the coating, and then treated in a sealed container with ammonia water for 24 hours. After the treatment is completed, the coating is pulled in colloid 2. The prepared silica film sample is clamped firmly and placed in a megasonic cleaning tank for cleaning. The cleaning time is adjusted according to the megasonic frequency and power. After the cleaned sample is dried naturally, it is characterized. The thickness of the silicon dioxide film is tested by ellipsometer, and the removal efficiency of the silicon dioxide film can be obtained by comparing the thickness change. Other characterizations and visual observations can be carried out by the methods described above.

[0033] This application uses a silicon dioxide film coated on a smooth substrate surface to evaluate the megasonic cleaning effect. Depending on the different surface properties of the substrate, nano-silica particles with different surface group characteristics are used to coat the film layer, which is then placed in a megasonic cleaning tank for cleaning. The megasonic cleaning effect is evaluated by optical microscopy analysis and other means.

[0034] By using the method for evaluating the megasonic cleaning effect based on silicon dioxide film provided in the present application, the strength distribution of the sound field in the megasonic cleaning tank can be obtained simply and quickly, the megasonic cleaning efficiency can be evaluated by detecting the amount of film removal, the shielding area of ​​the cleaning fixture to the megasonic field can be determined and the fixture design can be optimized accordingly, and the influence of megasonic frequency, power and other parameters on the film removal efficiency can be obtained. In addition, qualitative judgment can be made by visual observation of the silicon dioxide film on the surface of the substrate. In summary, the present application provides a low-cost and quick method for evaluating the effect of megasonic cleaning.

[0035] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0036] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for evaluating the megasonic cleaning effect based on silicon dioxide film, characterized in that: include: preparing silicon dioxide thin film samples; Placing the silicon dioxide film sample in a megasonic cleaning tank for megasonic cleaning; Obtaining characterization data of the silicon dioxide film sample before and after cleaning; the characterization data includes a transmission spectrum, a surface optical image, an atomic force image, and a thickness of the silicon dioxide film; The megasonic cleaning effect was evaluated based on the characterization data of the silica film samples before and after cleaning.

2. The method for evaluating the megasonic cleaning effect based on silicon dioxide film according to claim 1, characterized in that: Prepare silicon dioxide thin film samples, specifically including: The silicon dioxide nanoparticles are coated onto a substrate to prepare a silicon dioxide thin film sample.

3. The method for evaluating the megasonic cleaning effect based on silicon dioxide film according to claim 2, characterized in that: The substrate is silicon wafer, quartz or silicate glass.

4. The method for evaluating the megasonic cleaning effect based on silicon dioxide film according to claim 3, characterized in that: When the substrate is quartz or silicate glass, before coating the silicon dioxide nanoparticles on the substrate, the method further comprises: The substrate is ultrasonically cleaned in alkaline cleaning solution and pure water for 30 minutes respectively, with an ultrasonic frequency of 40kHz to 120kHz, and then slowly pulled and dehydrated in hot water; the pulling speed of the slow pulling and dehydration is 0.5mm / s to 1.5mm / s, and the temperature of the hot water is 45℃ to 60℃.

5. The method for evaluating the megasonic cleaning effect based on silicon dioxide film according to claim 3, characterized in that: When the substrate is silicon, before coating the silicon dioxide nanoparticles on the substrate, the method further comprises: The substrate was ultrasonically cleaned in acetone, anhydrous ethanol and distilled water for 15 minutes respectively, with an ultrasonic frequency of 40kHz to 120kHz, and then slowly pulled and dehydrated in anhydrous ethanol; the pulling speed of the slow pulling and dehydration drying was 0.5mm / s to 1.5mm / s.

6. The method for evaluating the megasonic cleaning effect based on silicon dioxide film according to claim 1, characterized in that: The thickness of silicon dioxide film was measured by ellipsometer.

7. The method for evaluating the megasonic cleaning effect based on silicon dioxide film according to claim 1, characterized in that: The transmission spectra of the silicon dioxide film samples before and after cleaning were tested using a spectrophotometer.

8. The method for evaluating the megasonic cleaning effect based on silicon dioxide film according to claim 1, characterized in that: The surface optical images of the silicon dioxide film samples before and after cleaning were tested using an optical microscope.

9. The method for evaluating the megasonic cleaning effect based on silicon dioxide film according to claim 1, characterized in that: Atomic force microscopy was used to test the atomic force images of silicon dioxide film samples before and after cleaning.

10. The method for evaluating the megasonic cleaning effect based on silicon dioxide film according to claim 6, characterized in that: The megasonic cleaning effect was evaluated based on the characterization data of the silica film samples before and after cleaning, including: The peeling condition of the silicon dioxide film is determined by comparing the transmission spectra of the silicon dioxide film samples before and after cleaning; By comparing the surface optical images of the silicon dioxide thin film sample before and after cleaning, the shielding condition of the silicon dioxide thin film sample by the cleaning fixture is determined; The removal efficiency of the silicon dioxide film is determined by comparing the depth and width of the pits or grooves in the atomic force image before and after the silicon dioxide film sample is cleaned; or the removal efficiency of the silicon dioxide film is determined by comparing the thickness of the silicon dioxide film before and after the silicon dioxide film sample is cleaned.

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