CN112882355B

CN112882355B - Method for narrowing photoetching line and photoetching machine

Info

Publication number: CN112882355B
Application number: CN202110253880.3A
Authority: CN
Inventors: 李荣宝
Original assignee: Shanghai Dabo Industrial Co ltd
Current assignee: Shanghai Dabo Industrial Co ltd
Priority date: 2021-03-09
Filing date: 2021-03-09
Publication date: 2023-05-23
Anticipated expiration: 2041-03-09
Also published as: CN112882355A; WO2022188250A1

Abstract

The invention relates to the technical field of lithography, in particular to a method for narrowing a lithography line and a lithography machine, which are used for carrying out at least two exposures so as to form a needed lithography part at the overlapped part of the at least two exposures. Compared with the prior art, the invention has the advantages of simple and feasible combined structure, and the invention has the following advantages: the method for narrowing the photoetching lines is originally designed, and the required photoetching part is formed at the overlapped part of the exposure through at least two times of sequential exposure, so that the defects of the prior art can be overcome, the nano-scale exposure requirement can be met, and the cost of the photoetching process can be reduced; a specific method and equipment structure for realizing mask displacement are also designed, and the mask displacement of nanometer level and sub-nanometer level is realized.

Description

Method for narrowing photoetching line and photoetching machine

Technical Field

The invention relates to the technical field of photoetching, in particular to a method for narrowing a photoetching line and a photoetching machine.

Background

Photolithography is a major process in the production of planar transistors and integrated circuits and is a process technique for scribing a mask (e.g., silicon dioxide) on the surface of a semiconductor wafer to effect localized diffusion of impurities.

Referring to fig. 1, in the conventional general photolithography process, photoresist is laid on a semiconductor wafer, and then a mask is disposed on the photoresist, and the mask is provided with a hollowed-out position according to requirements, so that a desired pattern can be left on the semiconductor wafer after performing operations of exposure, development and etching.

However, in exposure, the exposure of a pattern on the nanometer scale is not achieved for a long time due to the limitation of various factors such as the wavelength of the light emitted from the light source. In contrast, in the prior art, the light emitted from the light source is changed by an external device such as a lens, so that the wavelength is reduced, or the lithography is performed by using extreme ultraviolet light having a wavelength of 10 to 14 nm as the light source. However, the above method has problems such as high cost and difficulty in further narrowing the width of the photolithographic line, for example, exposure to extreme ultraviolet light can usually be performed only by an exposure width of 11 nm.

Disclosure of Invention

The invention aims to solve the defects of the prior art, and provides a method for narrowing a photoetching line and a photoetching machine, which can meet the nano-scale exposure requirement, are beneficial to narrowing the width of the photoetching line and are beneficial to reducing the cost of a photoetching process.

In order to achieve the above object, a method of narrowing a photolithographic line is devised, and at least two exposures are performed to form a desired photolithographic portion at overlapping portions of the at least two exposures.

The method for narrowing the photoetching lines also has the following preferable technical scheme:

the method comprises the following steps: s1, performing primary exposure, wherein the exposure degree is half of the required exposure degree; s2, moving or replacing the mask; s3, re-exposing, wherein the exposure degree is half of the required exposure degree; wherein the overlapping exposure portions of the two exposures form the lithography section.

The method comprises the following steps: s1, performing primary exposure; s2, moving or replacing the mask; s3, performing re-exposure; wherein the overlapping non-exposed portions of the two exposures form the lithography section.

The method for moving the mask in S2 comprises the following steps: be equipped with the connecting block between mask and mounting, the connecting block have a length be X's changeable section, exert effort F to mask, connecting block and mounting initially for the three is laminating each other in proper order, when needs make the mask carry out X's displacement, get rid of the changeable section of connecting block, can realize the displacement of mask.

The changeable section is a film obtained by a vacuum coating method.

The method for moving the mask in S2 comprises the following steps: be equipped with the connecting block between mask and mounting, the length of connecting block change along with the change of temperature, initially apply effort F to mask, connecting block and mounting for the three laminate in proper order, when the displacement that needs make the mask carry out X, change the temperature of connecting block make its length change, can realize the displacement of mask.

After S3, the lithography part is finally obtained by development and etching.

The invention also relates to a photoetching machine for the method for narrowing the photoetching lines, which comprises a light source and at least one mask plate.

The invention further relates to a photoetching machine for the method for narrowing the photoetching lines, which comprises a mask plate, a fixing piece and a connecting block, wherein the connecting block is arranged between the mask plate and the fixing piece and is provided with a changeable section with the length of X.

The invention also relates to a photoetching machine for the method for narrowing the photoetching lines, which comprises a mask plate, a fixing piece and a connecting block, wherein the connecting block is arranged between the mask plate and the fixing piece, and the length of the connecting block between the mask plate and the fixing piece changes along with the change of temperature.

Compared with the prior art, the invention has the advantages of simple and feasible combined structure, and the invention has the following advantages: the method for narrowing the photoetching lines is originally designed, and the required photoetching part is formed at the overlapped part of the exposure through at least two times of sequential exposure, so that the defects of the prior art can be overcome, the nano-scale exposure requirement can be met, and the cost of the photoetching process can be reduced; a specific method and equipment structure for realizing mask displacement are also designed, and the mask displacement of nanometer level and sub-nanometer level is realized.

Drawings

Fig. 1 is a schematic diagram of an exposure flow in the prior art.

Fig. 2 is a schematic view of the exposure process according to the present invention in example 1.

Fig. 3 is a schematic view of the exposure process according to the present invention in example 2.

Fig. 4 is a schematic diagram of a method for implementing mask displacement according to the present invention in embodiment 6.

FIG. 5 is an enlarged schematic view of a portion of a membrane for implementing the mask displacement method of the invention in example 6.

In the figure: 1. mask 2, photoresist 3, semiconductor wafer 4, scribe line 5, lithography section 6, first exposure section 7, overlap exposure section 8, non-hollowed-out section 9, first non-exposure section 10, overlap non-exposure section 11, fixture 12, connection block 13, and variable segments.

Detailed Description

The construction and principles of such apparatus and methods will be apparent to those skilled in the art from the following description of the invention taken in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

The present embodiment provides a method of narrowing a photolithographic line, performing at least two exposures to form a desired photolithographic portion at overlapping portions of the at least two exposures. Further examples are described below in conjunction with the drawings and examples.

Example 1

In this embodiment, two exposure operations are sequentially performed, and a desired pattern stripe is formed at the overlapping exposure position of the two exposures. The method comprises the following steps:

s1, performing primary exposure, wherein the exposure degree is half of the required exposure degree;

s2, moving the mask plate;

s3, re-exposing, wherein the exposure degree is half of the required exposure degree;

wherein, the overlapped exposure parts of the two exposures form the photoetching part, and the exposure degree can be adjusted by changing parameters such as exposure time, light source intensity and the like.

Specifically, as shown in fig. 2, in the photolithography process, a reticle with a width D is provided on the reticle.

In S1, first, the exposure is performed for T seconds, where T is half of the exposure time T required by the lithography section under the current illumination intensity, so that the line to be exposed of the resist is exposed for half of the time required to change its performance.

In S2, the mask plate and the semiconductor wafer are first moved by a distance X < D in a direction perpendicular to the lines that do not need to be exposed.

In S3, the exposure is again performed for t seconds, resulting in an effectively exposed line of D-X width as shown in fig. 2.

Example 2

In this embodiment, two exposure operations are performed sequentially, and desired pattern stripes are formed at overlapping non-exposure positions of the two exposures. The method comprises the following steps:

s1, performing primary exposure.

S2, moving the mask.

S3, performing re-exposure.

Wherein the overlapping non-exposed portions of the two exposures form the lithography section.

Specifically, in conjunction with fig. 3, in the photolithography process, a non-hollowed-out portion with a width D is provided on the mask, and the rest portions are hollowed-out scribe line positions.

In S1, first, the exposure is performed for t seconds, and a non-exposed line having a width D is obtained.

In S2, the mask plate and the semiconductor wafer are first moved by a distance X < D in a direction perpendicular to the lines to be exposed.

In S3, the non-exposed line is exposed again for t seconds, and a portion of length X in S1 is exposed, so that a non-exposed line of width D-X as shown in fig. 3 can be obtained.

Example 3

The steps of this embodiment are substantially the same as those of embodiment 1 and embodiment 2, except that the step of moving the mask in S2 is replaced with a replacement mask. At least two masks are prefabricated, and then the first exposure of S1 is performed, then the masks are replaced, and then the re-exposure is performed. Thus, the desired overlapping exposed portions are formed by the overlapping positions of the reticles of the two reticles, or the desired overlapping non-exposed portions are formed by the non-reticle portions of the two reticles.

Example 4

In the same pattern as that required by an actual circuit, there are sometimes a plurality of lines, and at this time, the operation is still performed according to the foregoing S1-S3, so as to simultaneously realize exposure of the plurality of lines. Specifically, in S2, the lines are moved by corresponding distances along the vertical direction of each line, and then the re-exposure operation in S3 is performed, so as to scribe a plurality of lines at the same time.

For example, the required lithography part has two mutually perpendicular lines, so in S2, after being displaced by a required distance in the perpendicular direction of the two lines, re-exposure is performed in S3, thereby realizing scribing of several lines with narrow width.

Example 5

In the same pattern required by the actual circuit, there are sometimes multiple lines, and at this time, the operations are still performed according to the foregoing S1-S3, so as to achieve exposure of the multiple lines, respectively. The steps S1-S3 are respectively carried out for a plurality of times to realize the scribing of a plurality of lines.

For example, the required lithography part has two mutually perpendicular lines, so that the first line is obtained by operating according to the steps of S1-S3, and then the second line is obtained by operating according to the steps of S1-S3 again, thereby realizing the scribing of a plurality of lines with narrow width.

Example 6

The embodiment exemplarily shows a method for realizing mask displacement, namely, position change of the mask is realized through a fixing piece and a connecting piece, the connecting piece is arranged between the mask and the fixing piece, the connecting piece is provided with a changeable section with the length of X, and acting force F is applied to the mask, the connecting piece and the fixing piece in the initial stage, so that the mask, the connecting piece and the fixing piece are sequentially and tightly attached. When the mask plate is required to be subjected to X displacement, the changeable section of the connecting block is removed, and the displacement of the mask plate can be realized.

For example, as shown in fig. 4 and fig. 5, the connecting block is fixed on the mask, a thin film is arranged on the contact surface of the connecting block and the fixing piece as a changeable section, the thickness of the film is displacement X required for narrowing the line width, and the film can be dissolved rapidly by the corresponding solvent.

And applying proper force F on two sides of the fixing piece and the mask plate to tightly press the fixing piece, the mask plate, the connecting block and the fixing piece, wherein the total length of the mask plate, the connecting block and the fixing piece is L. When the mask plate needs to be moved, the film is dissolved by adopting a corresponding solvent, so that the total length of the three is changed into L-X, and the mask plate realizes X displacement.

Wherein, the film can be obtained by a vacuum coating method, the vacuum coating technology is a mature prior art, and the main steps are as follows: the connecting block is placed in the vacuum cover, and one side needing the film plating is downward, and the surface area of the side is as small as possible so as to thoroughly dissolve the film. Meanwhile, an electric heating molybdenum boat and an electron gun are placed in the vacuum cover, and after the vacuum cover is closed, the vacuum is pumped to E-6 level. The method comprises the steps of heating and bombarding a plated object through an electron gun to evaporate the plated object into a molecular free state, filling the vacuum cover, enabling the side surface below the connecting block to be contacted with the molecules in the free state at first, forming a film on the side surface below the connecting block due to the action of molecular adsorption force, wherein the thickness of the film can be controlled according to evaporation capacity and evaporation time, and can be measured while coating, and the thickness of the coating can be controlled to be far lower than the sub-nanometer level.

Example 7

The embodiment further illustrates a method for realizing mask displacement, namely, the mask displacement is realized through the principle of thermal expansion and cold contraction. Be equipped with the connecting block between mask and mounting, the connecting block have the length along with the characteristic of temperature variation, the length of connecting block between mask and mounting along with temperature variation changes promptly, exert effort F to mask, connecting block and mounting initially for the three closely laminates in proper order. When the mask plate is required to be subjected to X displacement, the temperature of the connecting block is changed to change the length of the connecting block, so that the displacement of the mask plate can be realized.

For example, the connection block is made of a metallic material having a thermal expansion coefficient of the order of E-6. The specific temperature change of the connecting block can be obtained through calculation according to the required displacement amount, so that the nano-scale and even sub-nano-scale displacement of the mask plate can be realized.

Example 8

In this embodiment, after the scribing of the required lines is completed by the above method, the semiconductor wafer with the lithography part can be finally obtained by developing and etching.

Claims

1. A method for narrowing a lithographic line, characterized in that at least two exposures are performed, and in respect of the method for narrowing a lithographic line, the method comprises the steps of:

s1, performing primary exposure;

s2, moving the mask plate;

s3, performing re-exposure;

wherein the overlapping non-exposure portions of the two exposures form a lithography section;

or S1, performing primary exposure, wherein the exposure degree is half of the required exposure degree;

s2, moving the mask plate;

wherein, the overlapping exposure part of the two exposures forms a photoetching part;

the method for realizing the mask displacement in the S2 is also included, and specifically comprises the following steps:

a connecting block is arranged between the mask plate and the fixing piece, the connecting block and the mask plate are horizontally arranged, the connecting block is provided with a changeable section with the length of X, and acting force F is applied to the mask plate, the connecting block and the fixing piece at first so that the mask plate, the connecting block and the fixing piece are mutually attached in sequence, and when the mask plate is required to be subjected to X displacement, the changeable section of the connecting block is removed, so that the displacement of the mask plate can be realized;

or be equipped with the connecting block between mask version and mounting, connecting block and mask version level arrangement, the length of connecting block change along with the change of temperature, initially apply effort F to mask version, connecting block and mounting for the three laminate in proper order, when the displacement that needs to make the mask version carry out X, change the temperature of connecting block make its length change, can realize the displacement of mask version.

2. The method of narrowing a photolithographic line according to claim 1, wherein the variable segment is a film obtained by a vacuum plating method.

3. A method of narrowing a lithographic line according to claim 1, characterized in that after S3 the lithography section is finally obtained by development, etching.

4. A lithographic apparatus for use in a method of narrowing a lithographic line according to claim 1, comprising a light source and at least one reticle.

5. A lithographic apparatus for use in a method of narrowing a line of a lithographic apparatus according to claim 1, comprising a mask, a fixture and a connecting block, the connecting block being disposed between the mask and the fixture, the connecting block having a changeable section of length X.

6. A lithographic apparatus for use in a method of narrowing a line of a lithographic apparatus according to claim 1, comprising a mask, a fixing member, and a connecting block, the connecting block being disposed between the mask and the fixing member, the length of the connecting block between the mask and the fixing member being variable with temperature.