Method for improving tower-shaped defect of photoresist

Abstract

The invention provides a method for improving tower-shaped defects of photoresist, which comprises the following steps of: 1, providing a substrate, and forming the photoresist on the substrate; step 2, forming a pattern of a to-be-etched film layer target pattern in the photoresist; and step 3, removing aggregates and impurity residues through a wet cleaning process, and changing cleaning conditions when the wet cleaning process is implemented so as to improve the tower-shaped defect of the photoresist. Aiming at the principle that the tower-shaped defects of the photoresist occur in a production line, improvement is performed in a targeted manner, and small aggregates / fine impurities on the surface of a wafer subjected to dry etching of the photoresist are washed more powerfully by changing the condition of wet cleaning, so that the tower-shaped defects of the photoresist are improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more specifically to a method for improving tower-shaped defects in photoresist. Background Technology

[0002] Defects are a key concern in the semiconductor industry, and among them, photoresist tower defects are of paramount importance that need to be prevented and improved, as they directly affect the final yield. Photoresist tower defects generally refer to a series of prismatic dislocation rings stacked along the growth direction, formed by the collapse of vacancy accumulation due to fabrication / material reasons in the wafer. Current technologies have limited effectiveness in improving photoresist tower defects. Summary of the Invention

[0003] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a method for improving photoresist tower-shaped defects, in order to solve the problem that the existing technology has limited improvement effect on photoresist tower-shaped defects.

[0004] To achieve the above and other related objectives, this application provides a method for improving tower-like defects in photoresist, comprising: Step 1: Provide a substrate and form photoresist on the substrate; Step 2: Form a pattern of the target image of the film layer to be etched in the photoresist; Step 3: Remove aggregates and impurities by wet cleaning process. When implementing wet cleaning process, change the cleaning conditions to improve the tower-shaped defects of photoresist.

[0005] Preferably, the processing time of wet cleaning is increased to improve the tower-like defects of photoresist.

[0006] Preferably, a hydrofluoric acid treatment step is added to the wet cleaning process to improve the tower-like defects of the photoresist.

[0007] Preferably, the hydrofluoric acid treatment time is 10 seconds.

[0008] Preferably, hydrofluoric acid treatment is performed separately during wet cleaning to improve the tower-like defects of the photoresist.

[0009] Preferably, the hydrofluoric acid treatment time is 90 seconds.

[0010] Preferably, step two is performed using a photoresist dry etching process.

[0011] Preferably, photoresist is formed on the substrate by spin coating.

[0012] Preferably, after step three, the patterned photoresist is used as a mask to etch the film layer to be etched, forming the target pattern in the film layer to be etched.

[0013] Preferably, after implementing step three, a hard mask layer is first etched using patterned photoresist as a mask, and then the film layer to be etched is etched using patterned hard mask layer as a mask, forming the target pattern in the film layer to be etched.

[0014] As described above, the method for improving photoresist tower-shaped defects provided in this application has the following beneficial effects: it addresses the underlying principles of photoresist tower-shaped defects occurring in the production line by changing the conditions of wet cleaning to more forcefully rinse small aggregates / fine impurities on the wafer surface after dry photoresist etching, thereby improving the photoresist tower-shaped defects. Attached Figure Description

[0015] 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.

[0016] Figure 1 The flowchart shown is a method for improving photoresist tower-shaped defects provided in an embodiment of this application. Figure 2 The diagram shows a comparison of the effects of different cleaning conditions on the improvement of photoresist tower-shaped defects in the method for improving photoresist tower-shaped defects provided in the embodiments of this application. Detailed Implementation

[0017] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this invention.

[0018] 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.

[0019] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships, are 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, and therefore should not be construed as a limitation 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.

[0020] 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.

[0021] 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.

[0022] Please see Figure 1 The flowchart illustrates a method for improving photoresist tower-like defects provided in an embodiment of this application.

[0023] like Figure 1 As shown, the method for improving the tower-like defects in photoresist includes the following steps: Step 1: Provide a substrate and form photoresist on the substrate; Step 2: Form a pattern of the target image of the film layer to be etched in the photoresist; Step 3: Remove aggregates and impurities by wet cleaning process. When implementing wet cleaning process, change the cleaning conditions to improve the tower-shaped defects of photoresist.

[0024] In step one, a substrate is provided. Optionally, the substrate may be a silicon substrate, a germanium substrate, or a silicon-on-insulator substrate, etc.; or the substrate material may also include other materials, such as gallium arsenide or other III-V compounds. Those skilled in the art can select the substrate material according to the type of device structure formed on the substrate, therefore the type of substrate should not limit the scope of protection of this invention.

[0025] As an example, photoresist is formed on a substrate using a spin coating process.

[0026] In step two, a pattern of the target image of the film layer to be etched is formed in the photoresist using a photoresist dry etching process.

[0027] In step three, the ways to change the cleaning conditions include: increasing the processing time of wet cleaning; adding a hydrofluoric acid treatment step to wet cleaning, with the hydrofluoric acid treatment time being 10 seconds; or implementing hydrofluoric acid treatment alone in wet cleaning, with the hydrofluoric acid treatment time being 90 seconds.

[0028] See Figure 2 After performing conventional wet cleaning (using ST250 as the cleaning solution), the number of tower-shaped defects in the photoresist was 80ea, where ea represents the number of defects per wafer, with an extreme case of 500ea. After increasing the processing time of the wet cleaning, the number of tower-shaped defects in the photoresist decreased to 44ea. After adding a hydrofluoric acid treatment step to the wet cleaning process (ST250 first, then HF), the number of tower-shaped defects in the photoresist decreased to 20ea. After performing hydrofluoric acid treatment alone in the wet cleaning process, the number of tower-shaped defects in the photoresist decreased to 11ea.

[0029] After implementing step three, the film layer to be etched is etched using patterned photoresist as a mask to form the target pattern in the film layer to be etched. Alternatively, a hard mask layer is first etched using patterned photoresist as a mask, and then the film layer to be etched is etched using patterned hard mask layer as a mask to form the target pattern in the film layer to be etched.

[0030] Taking a hard mask layer consisting of a TEOS layer and a silicon nitride layer stacked from bottom to top, and a low-k dielectric layer as the film to be etched, as an example, compared to conventional wet cleaning (the cleaning solution for wet cleaning is ST250), the etching rate of hydrofluoric acid on the silicon nitride layer is 0. The concentration of hydrofluoric acid is low, and the etching rate on the TEOS layer is very small. There is no difference in the etching rate of ST250 and hydrofluoric acid on the low-k dielectric layer. Therefore, adding a hydrofluoric acid treatment step to the wet cleaning process or implementing hydrofluoric acid treatment alone are both risk-controllable.

[0031] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of this application. Therefore, the drawings only show the components related to this invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0032] In summary, the method for improving photoresist tower-shaped defects provided in this application specifically addresses the underlying principles that cause these defects in the production line. By altering the wet cleaning conditions, it more forcefully washes away small aggregates / fine impurities on the wafer surface after dry etching of the photoresist, thereby improving the photoresist tower-shaped defects. Therefore, this application effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0033] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this application.

Claims

1. A method for improving tower-shaped defects in photoresist, characterized in that, The method includes: Step 1: Provide a substrate and form photoresist on the substrate; Step 2: Form a pattern of the target pattern of the film layer to be etched in the photoresist; Step 3: Remove aggregates and impurity residues through a wet cleaning process. When implementing the wet cleaning process, change the cleaning conditions to improve the tower-shaped defects of the photoresist.

2. The method according to claim 1, characterized in that, Increase the processing time of the wet cleaning process to improve the tower-like defects of the photoresist.

3. The method according to claim 1, characterized in that, The wet cleaning process includes a hydrofluoric acid treatment step to improve the tower-like defects in the photoresist.

4. The method according to claim 3, characterized in that, The hydrofluoric acid treatment lasted for 10 seconds.

5. The method according to claim 1, characterized in that, Hydrofluoric acid treatment is performed separately during the wet cleaning process to improve the tower-like defects in the photoresist.

6. The method according to claim 5, characterized in that, The hydrofluoric acid treatment lasted for 90 seconds.

7. The method according to claim 1, characterized in that, Step two is performed using a photoresist dry etching process.

8. The method according to claim 1, characterized in that, The photoresist is formed on the substrate by spin coating.

9. The method according to claim 1, characterized in that, After performing step three, the patterned photoresist is used as a mask to etch the film layer to be etched, forming the target pattern in the film layer to be etched.

10. The method according to claim 1, characterized in that, After performing step three, the hard mask layer is first etched using patterned photoresist as a mask, and then the film layer to be etched is etched using the patterned hard mask layer as a mask, forming the target pattern in the film layer to be etched.

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