Photoresist development method

Abstract

The application relates to the technical field of semiconductor integrated circuit manufacturing, in particular to a photoresist developing method. The photoresist developing method comprises the following steps: in a static state, a first dose of a first developing solution is dropped on photoresist after wafer exposure, and the first developing solution is expanded on the photoresist to form a first convex liquid surface under the action of surface tension; the first convex liquid surface is allowed to stay on the photoresist for a first developing time, then the wafer is rotated at a first rotating speed for a first liquid throwing time, and then the wafer is increased to a second rotating speed on the basis of the first rotating speed, the wafer is rotated at the second rotating speed for a second liquid throwing time, and the first developing solution on the wafer is spun dry; wherein the first liquid throwing time is greater than the second liquid throwing time; in the static state, a second dose of a second developing solution is dropped on the wafer after the first developing solution is spun dry, and the second developing solution is expanded on the photoresist to form a second convex liquid surface under the action of surface tension; after the second convex liquid surface stays on the photoresist for a second developing time, the wafer is washed with deionized water and simultaneously spun dry at an increased rotating speed.

Description

Technical Field

[0001] This application relates to the field of semiconductor integrated circuit manufacturing technology, specifically to a photoresist development method. Background Technology

[0002] The integrated circuit manufacturing process mainly includes photolithography, etching, deposition, thin film processing, and chemical mechanical polishing. Among them, photolithography is the process of transferring a pre-designed mask pattern onto a wafer, which includes processes such as coating, exposure, and development.

[0003] During the development process, the formation of a positive photoresist film structure involves dissolving the exposed areas, while negative photoresist development removes the unexposed areas. Common development methods include immersion, spray, and puddle. The type of photoresist, its thickness, and the exposure wavelength affect the development steps and time in the development process. For example, the development time for immersion or puddle development is between 20-60 seconds, and should not exceed 120 seconds. Photoresist layers thicker than 10µm require 2-10 minutes of development, while those reaching 100µm require over 60 minutes.

[0004] I-line photoresist reacts to i-line (wavelength 365nm) ultraviolet light and is typically used for creating patterns with medium linewidths. I-line photoresist has a higher viscosity, resulting in a thicker photoresist layer. The development method for I-line photoresist is two-stage puddle development. After the first puddle development is completed, the first puddle developer is spun dry at high speed, and then the second puddle development is performed.

[0005] However, the high-speed spin-drying step after the first puddle development requires high precision. If a normal high-speed spin-drying method is used, the instantaneous speed difference will cause the developer to splash onto the surface of adjacent wafers, forming defects. Summary of the Invention

[0006] This application provides a photoresist development method that can solve the problem of developer splashing onto the surface of adjacent wafers in related technologies.

[0007] To address the technical problems described in the background art, this application provides a photoresist development method, which includes the following steps:

[0008] In a static state, a first dose of the first developer is dropped onto the photoresist after the wafer has been exposed. Under the action of surface tension, the first developer expands on the photoresist to form a first convex liquid surface.

[0009] After the first convex liquid surface remains on the photoresist for a first development time, the wafer is rotated at a first rotation speed for a first liquid-spinning time, and then the wafer is rotated at a second rotation speed for a second liquid-spinning time to dry the first developing solution on the wafer; wherein the first liquid-spinning time is longer than the second liquid-spinning time;

[0010] In a static state, a second dose of the second developer is dropped onto the wafer after the first developer has been spun dry. Under the action of surface tension, the second developer expands on the photoresist to form a second convex liquid surface.

[0011] After the second convex liquid surface remains on the photoresist for a second development time, the wafer is rinsed with deionized water while simultaneously increasing the rotation speed to spin dry.

[0012] Optionally, after the first convex liquid surface remains on the photoresist for a first development time, the wafer is rotated at a first rotation speed for a first spin-off time, and then the wafer is rotated at the second rotation speed for a second spin-off time to dry the first developer on the wafer; wherein the step of the first spin-off time being greater than the second spin-off time includes:

[0013] After the first convex liquid surface remains on the photoresist for a first development time, the wafer is rotated at a first speed of 100 rpm to 150 rpm for a first spin-off time of 5 to 10 seconds. Then, the wafer is rotated at a second speed of 400 rpm to 500 rpm based on the first speed of 100 rpm to 150 rpm, and rotated at the second speed of 400 rpm to 500 rpm for a second spin-off time of 1 to 5 seconds to dry the first developing solution on the wafer.

[0014] Optionally, the step of dropping a first dose of the first developer onto the photoresist after wafer exposure in a static state, and allowing the first developer to expand on the photoresist under surface tension to form a first convex liquid surface, includes:

[0015] In a static state, a first developer solution of 120ml to 180ml is dropped onto the photoresist after wafer exposure. Under the action of surface tension, the first developer solution expands on the photoresist to form a first convex liquid surface.

[0016] Optionally, after the first convex liquid surface remains on the photoresist for a first development time, the wafer is rotated at a first rotation speed for a first spin-off time, and then the wafer is rotated at the second rotation speed for a second spin-off time to dry the first developer on the wafer; wherein in the step where the first spin-off time is greater than the second spin-off time, the first development time is 5s to 10s.

[0017] Optionally, the step of dropping a second dose of the second developer onto the wafer after the first developer has been spun dry in a static state, and then, under the action of surface tension, allowing the second developer to expand on the photoresist to form a second convex liquid surface, includes:

[0018] In a static state, a second developer solution of 120ml to 180ml is dropped onto the wafer after the first developer solution has been spun dry. Under the action of surface tension, the second developer solution expands on the photoresist to form a second convex liquid surface.

[0019] Optionally, the step of rinsing the wafer with deionized water and simultaneously increasing the spin speed to dry it after the second convex liquid surface has remained on the photoresist for a second development period includes:

[0020] After the second convex liquid surface remains on the photoresist for a second development time of 5 to 10 seconds, the wafer is rinsed with deionized water and simultaneously spun dry at a higher speed.

[0021] Optionally, the step of rinsing the wafer with deionized water and simultaneously increasing the spin speed to dry it after the second convex liquid surface has remained on the photoresist for a second development time includes:

[0022] After the second convex liquid surface remains on the photoresist for a second development time, the wafer is rinsed with deionized water while the rotation speed is increased to 1500 rpm / s to 2000 rpm / s for spin drying.

[0023] The technical solution of this application has at least the following advantages: during the process of spin-drying the first developer on the wafer, a longer period of low-speed spin-drying is performed first, followed by a shorter period of medium-speed spin-drying, thereby forming a speed gradient. Most of the first developer is ejected from the wafer during the low-speed spin-drying process, thus avoiding the problem of the first developer splashing. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 A flowchart of a photoresist development method according to an embodiment of this application is shown. Detailed Implementation

[0026] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0029] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0030] Figure 1 A flowchart of a photoresist development method according to an embodiment of this application is shown. Figure 1 As can be seen from the above, the photoresist development method includes the following steps:

[0031] Step S1: In a static state, a first dose of the first developer is dropped onto the photoresist after the wafer has been exposed. Under the action of surface tension, the first developer expands on the photoresist to form a first convex liquid surface.

[0032] Specifically, a first dose of the first developer can be dropped onto the photoresist after wafer exposure using a scanning drop-coating method, with the first dose being 120ml to 180ml. After the first dose of 120ml to 180ml of the first developer is dropped within 4s to 6s, a first development time of 5s to 10s is allowed to ensure that the first developer fully reacts with the exposed photoresist.

[0033] Step S2: After the first convex liquid surface remains on the photoresist for a first development time, the wafer is rotated at a first rotation speed for a first liquid-spinning time, and then the wafer is rotated at a second rotation speed for a second liquid-spinning time to dry the first developer on the wafer; wherein the first liquid-spinning time is greater than the second liquid-spinning time.

[0034] For example, after the first convex liquid surface remains on the photoresist for a first development time, the wafer is rotated at a first speed of 100 rpm to 150 rpm for a first spin-off time of 5 to 10 seconds. Then, the wafer is rotated at a second speed of 400 rpm to 500 rpm based on the first speed of 100 rpm to 150 rpm for a second spin-off time of 1 to 5 seconds at the second speed of 400 rpm to spin-dry the first developing solution on the wafer.

[0035] During the process of spin-drying the first developer on the wafer, a longer period of low-speed spin-drying is performed first, followed by a shorter period of medium-speed spin-drying, thereby creating a speed gradient. This allows most of the first developer to be ejected from the wafer during the low-speed spin-drying process, thus avoiding the problem of the first developer splashing.

[0036] Step S3: In a static state, a second dose of the second developer is dropped onto the wafer after the first developer has been spun dry. Under the action of surface tension, the second developer expands on the photoresist to form a second convex liquid surface.

[0037] After the first developer is spun dry, a second dose of 120ml to 180ml of the second developer is dropped onto the wafer after the first developer has been spun dry. The second dose of the second developer is dropped on within 4s to 6s, and then left for a second development time of 5s to 10s to allow the second developer to fully react with the exposed photoresist.

[0038] For example, in a static state, 120 ml to 180 ml of the second dose of the second developer is dropped onto the wafer after the first developer has been spun dry. Under the action of surface tension, the second developer expands on the photoresist to form a second convex liquid surface.

[0039] Step S4: After the second convex liquid surface remains on the photoresist for a second development time, the wafer is rinsed with deionized water while simultaneously increasing the rotation speed to spin dry.

[0040] For example, after the second convex liquid surface remains on the photoresist for a second development time, the wafer is rinsed with deionized water and the rotation speed is increased to 1500 rpm / s to 2000 rpm / s for spin drying.

[0041] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A photoresist development method, characterized in that, The photoresist development method includes the following steps: In a static state, a first dose of the first developer is dropped onto the photoresist after the wafer has been exposed. Under the action of surface tension, the first developer expands on the photoresist to form a first convex liquid surface. After the first convex liquid surface remains on the photoresist for a first development time, the wafer is rotated at a first speed of 100 rpm to 150 rpm for a first spin-off time of 5 to 10 seconds. Then, the wafer is rotated at a second speed of 400 rpm to 500 rpm for a second spin-off time of 1 to 5 seconds to dry the first developing solution on the wafer. The first spin-off time is longer than the second spin-off time. In a static state, a second dose of the second developer is dropped onto the wafer after the first developer has been spun dry. Under the action of surface tension, the second developer expands on the photoresist to form a second convex liquid surface. After the second convex liquid surface remains on the photoresist for a second development time, the wafer is rinsed with deionized water and simultaneously spun dry at a higher speed.

2. The photoresist development method as described in claim 1, characterized in that, The step of dropping a first dose of the first developer onto the photoresist after wafer exposure in a static state, and allowing the first developer to expand on the photoresist under surface tension to form a first convex liquid surface, includes: In a static state, a first developer solution of 120ml to 180ml is dropped onto the photoresist after wafer exposure. Under the action of surface tension, the first developer solution expands on the photoresist to form a first convex liquid surface.

3. The photoresist development method as described in claim 1, characterized in that, After the first convex liquid surface remains on the photoresist for a first development time, the wafer is rotated at a first speed for a first liquid-spinning time, and then the wafer is increased to a second speed based on the first speed, and rotated at the second speed for a second liquid-spinning time to spin dry the first developing liquid on the wafer. In the step where the first liquid-spinning time is longer than the second liquid-spinning time, the first developing time is 5 to 10 seconds.

4. The photoresist development method as described in claim 1, characterized in that, The step of dropping a second dose of the second developer onto the wafer after the first developer has been spun dry, in a static state, and allowing the second developer to expand on the photoresist under the action of surface tension to form a second convex liquid surface, includes: In a static state, a second developer solution of 120ml to 180ml is dropped onto the wafer after the first developer solution has been spun dry. Under the action of surface tension, the second developer solution expands on the photoresist to form a second convex liquid surface.

5. The photoresist development method as described in claim 1, characterized in that, The step of rinsing the wafer with deionized water and simultaneously increasing the rotation speed to spin dry after the second convex liquid surface has remained on the photoresist for a second development time includes: After the second convex liquid surface remains on the photoresist for a second development time of 5 to 10 seconds, the wafer is rinsed with deionized water and simultaneously spun dry at a higher speed.

6. The photoresist development method as described in claim 1, characterized in that, The step of rinsing the wafer with deionized water and simultaneously increasing the rotation speed to spin dry after the second convex liquid surface has remained on the photoresist for a second development time includes: After the second convex liquid surface remains on the photoresist for a second development time, the wafer is rinsed with deionized water while the rotation speed is increased to 1500 rpm / s to 2000 rpm / s for spin drying.

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