Preparation method for improving defects of pixel film layer

Abstract

The invention discloses a preparation method for improving defects of a pixel film layer. The preparation method comprises the following steps: S10, carrying out surface pretreatment on a wafer substrate of a semiconductor; s20, performing multi-frequency ultrasonic cleaning on the wafer substrate of the semiconductor, wherein the liquid environment of a cleaning chamber is an organic chemical solvent; s30, cleaning liquid rotary spraying, multi-frequency ultrasonic cleaning and two-fluid water removal are carried out on the wafer substrate; s40, carrying out plasma cleaning on the wafer substrate; s50, carrying out post-baking treatment on the wafer substrate; and S60, coating the surface of the wafer substrate with an organic compound solvent for increasing the surface contact angle. According to the technical preparation method combining wafer substrate defect cleaning with wafer substrate surface treatment and coating uniformity, various types of defects in preparation of the pixel film layer are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor OLED manufacturing, and in particular relates to a preparation method for improving pixel film layer defects. Background Art

[0002] In semiconductor OLED process technology, pixel film preparation is an important technical step in the process. The traditional preparation step is to directly prepare the film layer pixels after cleaning the wafer substrate once.

[0003] However, in the preparation of pixel film layers in OLED process technology, on the one hand, the presence of metal crystals, environmental particles, waxy organic compounds and other residues on the surface of the wafer substrate causes the upper material to fall off due to poor adhesion, resulting in missing pixel film layers. On the other hand, due to the difference in mask polishing process accuracy of wafer substrates of various manufacturers, the flatness of the wafer substrate is poor, resulting in uneven coating of the film layer in the preparation process of the pixel film layer, abnormal pixel CD values, and ultimately pixel defects in the preparation process of the pixel film layer. Including Figure 1-Figure 3 The diagram shown is a schematic diagram of pixel film defects caused by poor wafer substrate flatness, a schematic diagram of pixel film defects caused by poor wafer substrate surface activity, and a schematic diagram of pixel film defects caused by wafer substrate surface defects.

[0004] Therefore, in order to further improve product production efficiency, product yield and performance, it is necessary to study a comprehensive preparation solution for wafer substrate defect cleaning, wafer substrate surface treatment and coating uniformity. Summary of the invention

[0005] The present invention is based on the current existing technical problems and provides a preparation method for improving pixel film defects, combining the process preparation method of wafer substrate defect cleaning and wafer substrate surface treatment and coating uniformity to improve various types of defects in pixel film preparation. It includes the following steps:

[0006] S10, performing surface pretreatment on a semiconductor wafer substrate;

[0007] S20, performing multi-frequency ultrasonic cleaning on the semiconductor wafer substrate, wherein the liquid environment of the cleaning chamber is an organic chemical solvent;

[0008] S30, performing a cleaning liquid rotary spraying, multi-frequency ultrasonic cleaning and two-fluid water removal on the wafer substrate;

[0009] S40, plasma cleaning the wafer substrate;

[0010] S50, performing post-baking treatment on the wafer substrate;

[0011] S60, coating the surface of the wafer substrate with an organic compound solvent for increasing the surface contact angle.

[0012] Preferably, the surface pretreatment in S10 includes sequentially performing high-temperature baking cooling, rotary spraying of cleaning liquid and vacuum ion cleaning.

[0013] Preferably, the S10 specifically includes the following steps:

[0014] S11, placing the wafer in a high temperature environment and baking it for 3 minutes to 10 minutes, the baking temperature is 30° C. to 60° C., and removing organic matter or organic film on the surface of the wafer by pyrolysis and / or volatilization;

[0015] S12, the wafer is subjected to rotational spraying of ultrapure water, the resistivity of which is 18.2MΩ·cm~18.3MΩ·cm, the particles ≥0.1um are less than 3 / ml (≤3 / ml), the total organic carbon content TOC is less than 30ppb (less than 1 part per billion), the bacterial count is less than 1cfu / L (less than 1 bacterial colony / liter), and the metal crystals and attachments ≥1.0um~50um on the surface of the wafer substrate are removed;

[0016] S13, placing the wafer in a vacuum plasma environment for cleaning, using plasma as a cleaning medium to further remove surface contaminants and oxides ≥ 0.5um, and to improve the surface activity of the wafer substrate.

[0017] Preferably, in S20, the wafer is placed in an organic chemical solvent environment for multi-frequency ultrasonic cleaning, wherein the ultrasonic cleaning frequency ranges from 20KHz to 150KHz, and the ultrasonic cleaning time is 3min to 15min, so as to remove pollutants and oxides ≥ 0.2um on the substrate surface.

[0018] Preferably, in S30, the wafer is placed in an ultrapure water environment for multi-frequency ultrasonic cleaning, wherein the ultrasonic cleaning frequency ranges from 40KHz to 150KHz, and the ultrasonic cleaning time is from 3min to 10min.

[0019] Preferably, after the ultrasonic cleaning in S30 is completed, nitrogen and oxygen are used as two-fluid gases to dehydrate the wafer substrate and remove particles with a size of ≥ 0.1 um on the surface of the wafer substrate.

[0020] Preferably, in S40, the wafer is placed in a vacuum plasma environment for cleaning, and the plasma cleaning temperature range is 50° C. to 130° C., so as to remove particles ≤ 0.1 um, continuously improve the surface activity of the wafer substrate, and increase the surface contact angle.

[0021] Preferably, the post-baking process in S50 includes sequentially performing high-temperature baking and cooling.

[0022] Preferably, the high temperature baking temperature in S50 is 60°C to 120°C.

[0023] Preferably, the cooling method in S50 is water circulation cooling.

[0024] Compared with the prior art, the present invention can effectively improve the defects of the wafer substrate while improving all aspects of the wafer substrate flatness, surface activity state, wafer electrical properties, etc., and by coating an organic solvent that increases the surface contact angle and surface activity of the material, the process yield of the wafer pixel film layer preparation is further improved. It is a pixel film layer preparation method with obvious benefits and wide practicality.

[0025] The present invention aims at solving the problems in the film layer pixel preparation process in the OLED manufacturing field due to wafer substrate defects, poor wafer substrate surface flatness, surface activity and contact angle improvement. The present invention studies methods such as adding wafer surface pretreatment, multiple ultrasonic cleanings, surface post-baking treatments, and organic solvent coating to the process, establishes an optimized film layer pixel preparation process flow, and realizes the process requirement of improving the film layer pixel defect incidence rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0027] Figure 1 A schematic diagram of pixel film defects caused by poor wafer substrate flatness in the prior art;

[0028] Figure 2 A schematic diagram of pixel film defects caused by wafer substrate surface activity in the prior art;

[0029] Figure 3 A schematic diagram of a pixel film layer defect caused by a wafer substrate surface defect in the prior art;

[0030] Figure 4 A flowchart of the steps of a preparation method for improving pixel film layer defects according to an embodiment of the present invention;

[0031] Figure 5 A diagram showing surface defects of a wafer substrate used in pixel preparation in the prior art;

[0032] Figure 6 A diagram showing the surface defect status of a wafer substrate used for preparing pixels using the preparation method for improving pixel film layer defects according to an embodiment of the present invention;

[0033] Figure 7 A diagram showing the flatness of a wafer substrate surface for preparing pixels according to an embodiment of the prior art;

[0034] Figure 8A diagram showing the surface flatness of a wafer substrate for pixel preparation according to another embodiment of the prior art;

[0035] Fig. 9 The diagram is a flatness status diagram of the surface of a wafer substrate used for preparing pixels using the preparation method for improving pixel film layer defects according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0037] See also Figure 4 The preparation method for improving pixel film defects of the present invention comprises the following steps:

[0038] S10, performing surface pretreatment on the semiconductor wafer substrate; wherein the surface pretreatment includes sequentially performing high temperature baking cooling, rotary spraying cleaning liquid and vacuum ion cleaning.

[0039] S20, performing multi-frequency ultrasonic cleaning on the semiconductor wafer substrate, the liquid environment of the cleaning chamber is an organic chemical solvent, specifically methyl ethyl ketone solution, butanol solution, dimethyl sulfoxide solution, ethanol solution, methanol solution, etc.; wherein the wafer is placed in an organic chemical solvent environment for multi-frequency ultrasonic cleaning, the ultrasonic cleaning frequency range is 20KHz ~ 150KHz, the ultrasonic cleaning time is 3min ~ 15min, and the contaminants and oxides ≥ 0.2um on the substrate surface are removed.

[0040] S30, the wafer substrate is subjected to rotary spraying of cleaning liquid, multi-frequency ultrasonic cleaning and two-fluid dehydration; the wafer is placed in an ultrapure water environment for multi-frequency ultrasonic cleaning, the ultrasonic cleaning frequency range is 40HKz~150KHz, and the ultrasonic cleaning time is 3min~10min. After the ultrasonic cleaning is completed, nitrogen and oxygen are used as two-fluid gases to dehydrate the wafer substrate to remove particles ≥0.1um on the surface of the wafer substrate.

[0041] S40, plasma cleaning the wafer substrate; the wafer is placed in a vacuum plasma environment for cleaning, the plasma cleaning temperature range is 50°C to 130°C, particles ≤ 0.1um are removed, and the surface activity of the wafer substrate is continuously improved to increase the surface contact angle.

[0042] S50, post-baking the wafer substrate; the post-baking treatment includes high-temperature baking and cooling in sequence, wherein the high-temperature baking temperature is 60°C to 120°C, and the cooling method is water circulation cooling. This step is to further optimize the wafer carrier mobility and electrical properties, while relieving the wafer stress and restoring its lattice structure.

[0043] S60, coating the surface of the wafer substrate with an organic compound solution that increases the surface contact angle, specifically trimethylphenylsilane solution, trimethylphenoxysilane solution, etc. The surface of the wafer is coated with an organic compound solution that increases the surface contact angle and surface activity of the material, laying a good product substrate foundation for the subsequent process of the film layer pixel.

[0044] In a specific embodiment, S10 specifically includes the following steps:

[0045] S11, placing the wafer in a high temperature environment and baking it for 3 minutes to 10 minutes, the baking temperature is 30° C. to 60° C., and removing organic matter or organic film on the surface of the wafer by pyrolysis and / or volatilization;

[0046] S12, the wafer is subjected to rotational spraying of ultrapure water, the resistivity of which is 18.2MΩ·cm~18.3MΩ·cm, the particles ≥0.1um are less than 3 / ml (≤3 / ml), the total organic carbon content TOC is less than 30ppb (less than 1 part per billion), the bacterial count is less than 1cfu / L (less than 1 bacterial colony / liter), and the metal crystals and attachments ≥1.0um~50um on the surface of the wafer substrate are removed;

[0047] S13, placing the wafer in a vacuum plasma environment for cleaning, using plasma as a cleaning medium to further remove surface contaminants and oxides ≥ 0.5um, and to improve the surface activity of the wafer substrate.

[0048] The pixel film layer was prepared using the above specific implementation method, and 16Pcs samples were selected to track the pixel film layer defect status (Table 1). The scanning results showed that there were no pixel film layer defects. Compared with the traditional film layer preparation method, the new invention method significantly improved the pixel film layer defect incidence rate.

[0049] Table 1

[0050]

[0051]

[0052] See also Figure 5 and Figure 6 The figures are a surface defect status diagram of a wafer substrate for preparing pixels in the prior art and a surface defect status diagram of a wafer substrate for preparing pixels using the preparation method for improving pixel film layer defects according to an embodiment of the present invention. An optical microscope is used to scan the wafer surface, and the pixel defects of the wafer surface film layer are plotted as point-like Mapping representations. It can be seen that the use of the present invention for pixel film layer preparation can effectively improve the current situation.

[0053] See also Figure 7 and Figure 8FIG. 1 is a diagram showing the surface flatness of a wafer substrate for preparing pixels in two embodiments of the prior art. Fig. 9 The surface flatness status diagram of the wafer substrate for pixel preparation using the preparation method for improving pixel film layer defects according to the embodiment of the present invention is shown. The uniformity of the film layer on the wafer surface is scanned using an ellipsometer. It can be seen that the film layer flatness in the prior art has the problem that the film layer thickness in the center of the wafer is relatively low, the film layer thickness at the edge of the wafer is high, and the film layer thickness distribution presents a "concave" shape. The film layer flatness obtained by the preparation method of the present invention effectively improves the flatness and coating uniformity of the film layer on the wafer surface compared with the prior art.

[0054] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation is within the protection scope required by the present invention.

[0055] The present invention is described in detail above, but the specific implementation of the present invention is not limited thereto. Those skilled in the art may make various modifications or alterations without departing from the spirit and scope of the claims of the present application.

Claims

1. A preparation method for improving pixel film defects, characterized in that: The following steps are involved: S10, performing surface pretreatment on a semiconductor wafer substrate; S20, performing multi-frequency ultrasonic cleaning on the semiconductor wafer substrate, wherein the liquid environment of the cleaning chamber is an organic chemical solvent; S30, performing a cleaning liquid rotary spraying, multi-frequency ultrasonic cleaning and two-fluid water removal on the wafer substrate; S40, performing plasma cleaning on the wafer substrate; S50, performing post-baking treatment on the wafer substrate; S60, coating the surface of the wafer substrate with an organic compound solvent for increasing the surface contact angle.

2. The method for improving pixel film defects according to claim 1, characterized in that: The surface pretreatment in S10 includes sequentially performing high temperature baking cooling, rotary spraying of cleaning liquid and vacuum ion cleaning.

3. The method for improving pixel film defects according to claim 1, characterized in that: The S10 specifically includes the following steps: S11, placing the wafer in a high temperature environment and baking it for 3 minutes to 10 minutes, the baking temperature is 30° C. to 60° C., and removing organic matter or organic film on the surface of the wafer by pyrolysis and / or volatilization; S12, the wafer is subjected to rotational spraying of ultrapure water, the resistivity of which is 18.2MΩ·cm~18.3MΩ·cm, the particles ≥0.1um are less than 3 / ml, the total organic carbon content TOC is less than 30ppb, i.e., less than 1 part per billion, the bacterial count is less than 1cfu / L, i.e., less than 1 bacterial colony / liter, and the metal crystals and attachments ≥1.0um~50um on the surface of the wafer substrate are removed; S13, placing the wafer in a vacuum plasma environment for cleaning, using plasma as a cleaning medium to further remove surface contaminants and oxides ≥ 0.5um, and to improve the surface activity of the wafer substrate.

4. The method for improving pixel film defects according to claim 1, characterized in that: In the S20, the wafer is placed in an organic chemical solvent environment for multi-frequency ultrasonic cleaning, wherein the ultrasonic cleaning frequency ranges from 20KHz to 150KHz, and the ultrasonic cleaning time is from 3min to 15min, to remove pollutants and oxides ≥ 0.2um on the substrate surface.

5. The method for improving pixel film defects according to claim 1, characterized in that: In the S30, the wafer is placed in an ultrapure water environment for multi-frequency ultrasonic cleaning, wherein the ultrasonic cleaning frequency ranges from 40KHz to 150KHz, and the ultrasonic cleaning time is from 3min to 10min.

6. The method for improving pixel film defects according to claim 5, characterized in that: After the ultrasonic cleaning in S30 is completed, nitrogen and oxygen are used as two-fluid gases to dehydrate the wafer substrate and remove particles with a size of ≥ 0.1 um on the surface of the wafer substrate.

7. The method for improving pixel film defects according to claim 1, characterized in that: In the S40 , the wafer is placed in a vacuum plasma environment for cleaning, and the plasma cleaning temperature range is 50° C. to 130° C., to remove particles ≤ 0.1 um, and to continuously improve the surface activity of the wafer substrate and increase the surface contact angle.

8. The method for improving pixel film defects according to claim 1, characterized in that: The post-baking process in S50 includes sequentially performing high-temperature baking and cooling.

9. The method for improving pixel film defects according to claim 8, characterized in that: The high temperature baking temperature in S50 is 60°C to 120°C.

10. The method for improving pixel film defects according to claim 1, characterized in that: The cooling method in S50 is water circulation cooling.

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