CN113204172A

CN113204172A - Photoresist coating method

Info

Publication number: CN113204172A
Application number: CN202110410016.XA
Authority: CN
Inventors: 栾会倩; 吴长明; 姚振海
Original assignee: Hua Hong Semiconductor Wuxi Co Ltd
Current assignee: Hua Hong Semiconductor Wuxi Co Ltd
Priority date: 2021-04-16
Filing date: 2021-04-16
Publication date: 2021-08-03

Abstract

The application discloses a photoresist coating method, which relates to the field of semiconductor manufacturing. The photoresist coating method includes placing a wafer on a wafer carrier; spraying photoresist on the surface of the wafer; driving the wafer carrier to drive the wafer to rotate, and the rotational speed is greater than 2000 rpm, and The rotation time is less than 2 seconds; the wafer carrier is driven to drive the wafer to rotate at a predetermined rotational speed within a predetermined time; it solves the problem that the CD uniformity is affected after the photoresist is spin-coated when there is a high-step structure on the wafer surface at present. It achieves the effect of improving the followability of the coated photoresist, making the photoresist film thickness on the wafer surface more uniform, and improving the uniformity of the pattern CD.

Description

Photoresist coating method

Technical Field

The application relates to the field of semiconductor manufacturing, in particular to a photoresist coating method.

Background

Photolithography is one of the most critical processes in the field of semiconductor manufacturing. The photoetching process transfers a pre-designed pattern into photoresist on the surface of a substrate, and the main steps of the photoetching process comprise gluing, exposure and development, wherein the gluing process aims to form a uniform photoresist film layer on the surface of the substrate.

CD (Critical dimension) in the photolithography process is greatly affected by the photoresist thickness. For part of photoetching layers, because of the existence of high steps in the previous layer structure, the photoresist thickness difference at different positions is easy to be larger, and further the uniformity of CD is poor.

Disclosure of Invention

To solve the problems in the related art, the present application provides a photoresist coating method. The technical scheme is as follows:

in a first aspect, an embodiment of the present application provides a photoresist coating method, including:

placing a wafer on the wafer bearing table;

spraying photoresist on the surface of the wafer;

driving the wafer bearing table to drive the wafer to rotate, wherein the rotating speed is greater than 2000 rpm, and the rotating time is less than 2 seconds;

the wafer bearing table is driven to drive the wafer to rotate according to the preset rotating speed within the preset time.

Optionally, the driving of the wafer bearing table drives the wafer to rotate at a predetermined rotation speed within a predetermined time includes:

the wafer bearing table is driven to drive the wafer to rotate twice within a preset time according to a preset rotating speed.

Optionally, when the size of the wafer is 12 inches, the predetermined rotation speed is a rotation speed of not more than 2000 rpm.

Optionally, when the size of the wafer is 8 inches, the predetermined rotation speed is a rotation speed of not more than 3500 rotations/minute.

Optionally, when the wafer size is 6 inches, the predetermined speed is no greater than 4500 rpm.

The technical scheme at least comprises the following advantages:

the wafer is placed on the wafer bearing platform, photoresist is sprayed on the surface of the wafer, the wafer bearing platform is driven to drive the wafer to rotate at a high speed for a short time, and then the wafer bearing platform is driven to drive the wafer to rotate at a preset rotating speed within preset time, so that the photoresist on the surface of the wafer is coated; the problem that CD uniformity is influenced after photoresist is spin-coated when a high-step structure exists on the surface of a wafer at present is solved; the effects of improving the follow-up property of coating the photoresist, enabling the thickness of the photoresist film on the surface of the wafer to be more uniform and improving the uniformity of the pattern CD are achieved.

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 photoresist coating method provided by an embodiment of the present application;

fig. 2 is a partial schematic view of a wafer coated with a photoresist according to an embodiment of the present disclosure.

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, a flow chart of a photoresist coating method according to an embodiment of the present application is shown, the method at least includes the following steps:

step 101, a wafer is placed on a wafer bearing table.

And placing the wafer on a wafer bearing table, and spraying a pre-wetting solvent to the wafer to pre-wet the wafer.

Step 102, spraying photoresist on the surface of the wafer.

And spraying photoresist to the wafer by using a photoresist sprayer.

And 103, driving the wafer bearing table to drive the wafer to rotate, wherein the rotating speed is greater than 2000 rpm, and the rotating time is less than 2 seconds.

In order to make the compliance (compliance) of the photoresist film layer better after the photoresist is coated on the wafer with the high step, before the main spin coating of the photoresist, a pre-spin coating is performed first, that is, the wafer is rotated for less than 2 seconds at a rotation speed of more than 2000 rpm.

Step 104, driving the wafer carrying platform to drive the wafer to rotate at a predetermined rotation speed within a predetermined time.

The wafer is subjected to main spin coating of photoresist, and the rotation speed and the rotation time in the step are determined by the expected film thickness of the photoresist on the surface of the wafer.

The preset time and the preset rotating speed are determined in advance according to the wafer size and the expected film thickness of the photoresist.

After the photoresist spin coating in step 104, the surface of the wafer is uniformly covered with a photoresist film layer.

In one example, as shown in fig. 2, the surface of the wafer 21 has a high step structure 22, and after the photoresist spin coating in steps 102 to 104, the thicknesses of the photoresist 23 at different positions are close, which is beneficial to improving the CD uniformity of the wafer surface pattern.

In summary, in the photoresist coating method provided by the embodiment of the present application, a wafer is placed on a wafer bearing table, a photoresist is sprayed on the surface of the wafer, the wafer bearing table is driven to drive the wafer to rotate at a high speed for a short time, and then the wafer bearing table is driven to drive the wafer to rotate at a predetermined rotation speed within a predetermined time, so as to complete coating of the photoresist on the surface of the wafer; the problem that CD uniformity is influenced after photoresist is spin-coated when a high-step structure exists on the surface of a wafer at present is solved; the effects of improving the follow-up property of coating the photoresist, enabling the thickness of the photoresist film on the surface of the wafer to be more uniform and improving the uniformity of the pattern CD are achieved.

In an alternative embodiment based on the embodiment shown in fig. 1, the above step 104 can be implemented as follows:

Firstly, moving a wafer bearing platform to drive a wafer to carry out primary spin coating; then driving the wafer bearing platform to drive the wafer to carry out secondary main spin coating; the time of the first main spin coating and the time of the second main spin coating are predetermined; the rotation speed of the first main spin coating and the rotation speed of the second main spin coating are predetermined.

Optionally, the time of the first main spin coating is longer than that of the second main spin coating.

Optionally, the rotation speed of the first main spin coating is the same as that of the second main spin coating, or the rotation speed of the first main spin coating is different from that of the second main spin coating.

When the main spin coating in the photoresist coating process is carried out, the preset rotating speed is different according to different wafer sizes.

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.

Claims

1. A photoresist coating method, comprising:

placing a wafer on the wafer bearing table;

spraying photoresist on the surface of the wafer;

and driving the wafer bearing table to drive the wafer to rotate according to a preset rotating speed within a preset time.

2. The method of claim 1, wherein driving the wafer stage to rotate the wafer at a predetermined speed for a predetermined time comprises:

and driving the wafer bearing table to drive the wafer to rotate twice within preset time according to a preset rotating speed.

3. The method of claim 1, wherein the predetermined rotation rate is a rotation rate of not greater than 2000 rpm when the wafer is 12 inches in size.

4. The method of claim 1, wherein the predetermined rotational speed is a rotational speed of no greater than 3500 revolutions per minute when the wafer is 8 inches in size.

5. The method of claim 1 wherein the predetermined speed is a speed no greater than 4500 rpm when the wafer is 6 inches in size.