阅读说明：本技术 光刻方法 (Photoetching method ) 是由 谷云鹏 吴长明 姚振海 陈骆 郭星 王城燚 于 2021-07-28 设计创作，主要内容包括：本申请公开了一种光刻方法,包括：在晶圆上涂布光阻,该光阻为正性光阻；对光阻进行软烘烤；对光阻进行曝光后,进行冷却以释放在曝光过程中产生的气体；对光阻进行曝光后的烘烤；对光阻进行显影。本申请通过在光刻过程中,在对光阻进行曝光后进行冷却以释放曝光中产生的气体,避免留存在光阻中的气体在后续的烘烤过程中受热膨胀产生缺陷,从而能够在一定程度上降低了光刻过程中形成气泡的几率,降低了光刻图形的缺陷,提高了产品的可靠性和良率。(The application discloses a photoetching method, which comprises the following steps: coating a photoresist on the wafer, wherein the photoresist is a positive photoresist; soft baking the photoresist; after exposing the photoresist, cooling the photoresist to release gas generated in the exposure process; baking the photoresist after exposure; and developing the photoresist. This application is through at the photoetching in-process, cools off the gas that produces in order to release the exposure after exposing the photoresistor, avoids the gas of surviving in the photoresistor to be heated the inflation and produce the defect in subsequent baking process to can reduce the probability of photoetching in-process bubble formation to a certain extent, reduce the defect of photoetching the figure, improve the reliability and the yield of product.)

1. A lithographic method, comprising:

coating a photoresist on the wafer, wherein the photoresist is a positive photoresist;

soft baking the light resistance;

after exposing the light resistance, cooling the light resistance to release gas generated in the exposure process;

baking the photoresist after exposure;

and developing the exposed photoresist.

2. The method of claim 1, wherein the photoresist comprises diazonaphthoquinone.

3. The method of claim 2, wherein the photoresist is coated on the wafer to a thickness greater than 4 microns.

4. The method of claim 3, wherein the photoresist is cooled for a period of time of 60 seconds to 150 seconds after the exposing.

5. The method of any one of claims 1 to 4, wherein the coating of the photoresist on the wafer comprises:

placing the wafer on a gluing machine table;

and dropping a light resistance on the surface of the wafer, and rotating the wafer to coat the light resistance on the surface of the wafer.

6. The method of claim 5, wherein cooling is required after the post exposure baking of the photoresist.

7. The method of claim 6, wherein the wafer is a 12 inch process wafer.

Technical Field

The application relates to the technical field of semiconductor manufacturing, in particular to a photoetching method.

Background

The patterning refers to various processes for creating a pattern on a wafer, which is one of the most important processes in a semiconductor process, and is a process for creating a pattern between different devices and circuits, wherein a photolithography process is one of important patterning processes.

The photolithography process includes the steps of coating photoresist, exposing, developing, etc. However, after exposure, since the gas in the photoresist is difficult to release, bubbles remain in the photoresist to form defects. In the related art, after exposure, a post-bake is often performed, so that bubbles in the photoresist expand, and damage of the defect to the pattern increases.

Accordingly, a photolithography method is needed to remove the exposed bubbles without additional processes, so as to reduce the damage of the defect to the pattern.

Disclosure of Invention

The application provides a photoetching method which can solve the problem that bubbles are easily generated after exposure in the photoetching method provided by the related technology.

In one aspect, an embodiment of the present application provides a photolithography method, including:

coating a photoresist on the wafer, wherein the photoresist is a positive photoresist;

soft baking the light resistance;

after exposing the light resistance, cooling the light resistance to release gas generated in the exposure process;

baking the photoresist after exposure;

and developing the exposed photoresist.

Optionally, the photoresist comprises Diazonaphthoquinone (DNQ).

Optionally, after the photoresist is coated on the wafer, the thickness of the photoresist is greater than 4 micrometers (μm).

Optionally, after the exposure of the photoresist, the cooling time is 60 seconds(s) to 150 seconds.

Optionally, the coating of the photoresist on the wafer includes:

placing the wafer on a gluing machine table;

and dropping a light resistance on the surface of the wafer, and rotating the wafer to coat the light resistance on the surface of the wafer.

Optionally, after baking the photoresist after exposure, cooling is also required.

Optionally, the wafer is a 12-inch process wafer.

The technical scheme at least comprises the following advantages:

in the photoetching process, the photoresist is cooled after being exposed so as to release gas generated in the exposure, and the defect caused by the fact that the gas remained in the photoresist expands when heated in the subsequent baking process is avoided, so that the probability of forming bubbles in the photoetching process is reduced to a certain extent, the defect of photoetching patterns is reduced, and the reliability and the yield of products are improved.

Drawings

In order to more clearly illustrate the detailed description of the present application or the technical solutions in the prior art, the drawings needed to be used in the detailed description of the present application or the prior art description will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a flow chart of a lithographic method provided in an exemplary embodiment of the present application.

Detailed Description

The technical solutions in the present application will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; the connection can be mechanical connection or electrical connection; the two elements may be directly connected or indirectly connected through an intermediate medium, or may be communicated with each other inside the two elements, or may be wirelessly connected or wired connected. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

In addition, the technical features mentioned in the different embodiments of the present application described below may be combined with each other as long as they do not conflict with each other.

Referring to fig. 1, there is shown a flow chart of a lithographic method provided by an exemplary embodiment of the present application, the method including:

step 101, coating a photoresist on a wafer, wherein the photoresist is a positive photoresist.

Wherein the wafer may be a 12-inch process wafer and the photoresist coating process may be performed on a coater station. For example, a wafer may be placed on a coater station; and (3) dropping a photoresist on the surface of the wafer, and rotating the wafer to coat the photoresist on the surface of the wafer, thereby coating the photoresist on the wafer. Optionally, after the photoresist is coated on the wafer, the thickness of the photoresist is greater than 4 μm.

And 102, soft baking the photo resistor.

The soft bake is performed to harden the photoresist, thereby facilitating subsequent exposure.

Step 103, after the photoresist is exposed, cooling is performed to release gas generated during the exposure process.

For example, the photoresist may be exposed through a mask plate, and light may pass through the mask plateAnd exposing the photoresist under the hollow pattern. In the case that the photoresist contains diazonaphthoquinone, the diazonaphthoquinone generates indene formic acid and releases nitrogen (N) during the exposure process₂) If the photoresist is not released after exposure or is thermally aggregated and expanded, nitrogen bubble defects may be formed between the photoresist layers.

In view of this, in the embodiment of the present application, after the exposure, the photoresist may be cooled to release the gas generated during the exposure (e.g. nitrogen gas generated from diazonaphthoquinone), so as to avoid the defect caused by thermal expansion of the gas remained in the photoresist during the subsequent baking process.

Optionally, the cooling time is 60 seconds to 150 seconds. The bubble removal in the photoresist can be realized only by adding a cooling step after exposure without adding an additional bubble removal step, so that the cost is low and the method is easy to realize on the basis of reducing the probability of bubble formation in the photoetching process to a certain extent.

And 104, baking the photoresist after exposure.

Post Exposure Bake (PEB) is performed to reduce the effect of standing wave effects and to make the chemical reaction more complete. Optionally, the post-exposure bake includes a bake process and a post-bake cooling process. Since the gas is released by cooling in step 103, most of the gas remaining in the photoresist is removed, reducing the generation of defects.

Step 105, developing the exposed photoresist.

For example, the wafer may be immersed in a developer of a developing machine for developing, thereby forming a photoresist pattern.

To sum up, in the embodiment of the application, through in the photoetching process, the photoresistor is cooled after being exposed so as to release the gas generated in the exposure, the defect caused by the fact that the gas remained in the photoresistor expands when being heated in the subsequent baking process is avoided, and therefore the probability of forming bubbles in the photoetching process is reduced to a certain extent, the defect of photoetching patterns is reduced, and the reliability and the yield of products are improved.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of this invention are intended to be covered by the scope of the invention as expressed herein.