阅读说明：本技术 消除光刻显影残留的方法 (Method for eliminating photoetching development residue ) 是由 刘俊 于 2021-07-07 设计创作，主要内容包括：本发明公开了一种消除光刻显影残留的方法,在晶圆完成清洗干燥之后,在晶圆上涂光刻胶,经坚膜之后进行曝光及烘烤,然后放入显影液中进行显影步骤；在显影时,对晶圆表面喷涂显影液,使显影液与曝光之后的光刻胶进行反应,显影完成之后对所述晶圆表面进行冲洗,以去除已经发生聚合反应的光刻胶；在冲洗时,晶圆承台带动晶圆进行顺时针及逆时针的交替旋转,向晶圆上喷洒清洗液；清除晶圆上需要被去除的光刻胶。本发明方法在清洗时将晶圆正反向交替旋转,使晶圆上的显影残留能被多方向的冲击力震离晶圆表面,克服了单向旋转时某些图形对残留光刻胶的阻挡,使之难以被从晶圆上去除的问题。(The invention discloses a method for eliminating photoetching development residues, which comprises the steps of coating photoresist on a wafer after the wafer is cleaned and dried, carrying out exposure and baking after hardening, and then putting the wafer into a developing solution for developing; during development, spraying a developing solution on the surface of the wafer to enable the developing solution to react with the exposed photoresist, and after the development is finished, washing the surface of the wafer to remove the photoresist which has undergone polymerization reaction; during washing, the wafer bearing platform drives the wafer to alternately rotate clockwise and anticlockwise, and cleaning solution is sprayed on the wafer; and removing the photoresist on the wafer which needs to be removed. The method of the invention rotates the wafer in the positive and negative directions alternatively during cleaning, so that the developing residue on the wafer can be shaken off the surface of the wafer by multidirectional impact force, and the problem that the residual photoresist is difficult to remove from the wafer due to the blocking of certain patterns during unidirectional rotation is solved.)

1. A method for eliminating photoetching development residues is characterized in that: after the wafer is cleaned and dried, coating photoresist on the wafer, hardening the photoresist, exposing and baking the photoresist, and then putting the photoresist into a developing solution for developing;

during development, spraying a developing solution on the surface of the wafer to enable the developing solution to react with the exposed photoresist, and after the development is finished, washing the surface of the wafer to remove the photoresist which has undergone polymerization reaction;

during washing, the wafer bearing platform drives the wafer to alternately rotate clockwise and anticlockwise, and cleaning solution is sprayed on the wafer; and removing the photoresist on the wafer which needs to be removed.

2. The method of removing lithographic development residue of claim 1, wherein: the photoresist comprises positive photoresist or negative photoresist.

3. The method of removing lithographic development residue of claim 1, wherein: the developing solution reacts with the exposed photoresist, and the developing solution and the photoresist need to react sufficiently, so that the photoresist in the exposure area is sufficiently dissolved by the developing solution.

4. The method of removing lithographic development residue of claim 1, wherein: when the positive photoresist is used, the cleaning liquid is ultrapure water; when the negative photoresist is used, the cleaning solution is n-butyl acetate.

5. The method of removing lithographic development residue of claim 1, wherein: the wafer bearing platform drives the wafer to alternately rotate clockwise and anticlockwise, and the wafer is accelerated to a stable rotating speed or a standard process rotating speed from a static state gradually in a clockwise direction, then is decelerated to the static state gradually, is switched to the anticlockwise direction, is accelerated to the stable rotating speed or the standard process rotating speed gradually, and then is decelerated to the static state gradually; the next process is then repeated.

6. The method of removing lithographic development residue of claim 5, wherein: the residual photoresist at certain specific positions on the wafer can be removed by the clockwise and anticlockwise alternate rotation of the wafer so as to eliminate the development residue; the specific position refers to a position of a pattern on the wafer where certain patterns can form blocking, so that the photoresist needing to be removed is difficult to be thrown away from the surface of the wafer when the photoresist is rotated in a single direction, but the blocking can be eliminated through reverse rotation, so that the photoresist can be removed.

7. The method of removing lithographic development residue of claim 6, wherein: the development residue is formed by the fact that after the developing solution and the photoresist fully react, the part of the original photoresist which needs to be removed remains on the silicon wafer.

Technical Field

The invention relates to the field of semiconductor device manufacturing, in particular to a method for eliminating photoetching developing solution residues in a photoetching process.

Background

In the manufacture of semiconductor devices, photolithography is one of the most important processes. The photolithography process enables the design pattern to be accurately reproduced on the silicon wafer. Photoresists are important raw materials required in the photolithography process and are divided into positive and negative resists. Taking the process of selecting the positive photoresist as an example, after the photoresist below the part without pattern shielding of the mask is exposed, the photoresist and the developing solution are subjected to decomposition reaction and removed. Leaving the photoresist portions unexposed. In this process, if the photoresist on some special pattern at a specific position of the silicon wafer is exposed and undergoes decomposition reaction with the developing solution, it is not removed cleanly. Development residue is left and pattern defects are caused.

In the current developing process, in the step of photoetching, developing and flushing (ring), a silicon wafer rotates clockwise in a single direction, so that developing residues of certain patterns exist at a certain special position of the silicon wafer easily. In a top view angle, as shown in fig. 1, the silicon wafer is driven by the stage to rotate clockwise, and when the silicon wafer is accelerated from a standstill and rotates clockwise, a force applied to the photoresist layer on the silicon wafer is a friction force, and the direction of the friction force is opposite to the clockwise direction of the movement of the silicon wafer, as shown by a solid arrow in the figure. The two sides are small square boxes which are local enlargements of different areas on the silicon chip, and different photoetching patterns and friction directions are arranged in the different areas on the silicon chip. In the enlarged partial view of fig. 2, the flow resistance is increased at the position circled by the dotted line due to the higher resist block above and to the right. Eventually causing development to remain at the black graphic.

The pattern is located at the right angle of the photoresist right angle pattern. Meanwhile, one side of the right-angle pattern is perpendicular to the radius direction of the silicon chip, and the right-angle side is positioned between the pattern and the center of the silicon chip.

When the silicon wafer rotates clockwise stably, the photoresist layer on the silicon wafer is stressed in the outward direction of the rotation center by centrifugal force. At this time, since the pattern on the silicon wafer is also rotated clockwise, there is no special feature at the dotted circle in fig. 1, and it is impossible to cause the photoresist residue on the silicon wafer only at the position shown in the figure. Finally, as shown in fig. 2, in many areas on the silicon wafer, after development and cleaning, the photoresist in the exposed areas is not removed completely.

Disclosure of Invention

The invention aims to provide a method for eliminating photoetching development residues.

In order to solve the problems, the method for eliminating the photoetching development residue comprises the steps of coating photoresist on a wafer after the wafer is cleaned and dried, carrying out exposure and baking after hardening, and then carrying out development in a developing solution;

during development, spraying a developing solution on the surface of the wafer to enable the developing solution to react with the exposed photoresist, and after the development is finished, washing the surface of the wafer to remove the photoresist which has undergone polymerization reaction;

during washing, the wafer bearing platform drives the wafer to alternately rotate clockwise and anticlockwise, and cleaning solution is sprayed on the wafer; and removing the photoresist on the wafer which needs to be removed.

In a further improvement, the photoresist comprises a positive photoresist or a negative photoresist.

The further improvement is that the developing solution reacts with the photoresist after exposure, and the developing solution needs to fully react with the photoresist, so that the photoresist in the exposure area is fully dissolved by the developing solution.

The further improvement is that the cleaning solution is sprayed on the wafer, and when the positive photoresist is used, the cleaning solution is ultrapure water; when the negative photoresist is used, the cleaning solution is n-butyl acetate.

The wafer bearing platform drives the wafer to alternately rotate clockwise and anticlockwise, and the wafer is accelerated to a stable rotating speed or a standard process rotating speed from a static state gradually in a clockwise direction, then is decelerated to the static state gradually, is switched to the anticlockwise direction, is accelerated to the stable rotating speed or the standard process rotating speed gradually, and then is decelerated to the static state gradually; the next process is then repeated.

The further improvement is that through the clockwise and anticlockwise alternate rotation of the wafer, the residual photoresist at certain positions on the wafer can be removed to eliminate the development residue; the specific position refers to a position of a pattern on the wafer where certain patterns can form blocking, so that the photoresist needing to be removed is difficult to be thrown away from the surface of the wafer when the photoresist is rotated in a single direction, but the blocking can be eliminated through reverse rotation, so that the photoresist can be removed.

The further improvement is that the developing residue is formed by the residual part of the original photoresist which needs to be removed on the silicon wafer after the developing solution fully reacts with the photoresist.

The method for eliminating the photoetching development residues aims at the problem of the development residues in the development process after photoetching, and the development residues on the wafer can be shaken off the surface of the wafer by multidirectional impact force by alternately rotating the wafer in the forward direction and the reverse direction during cleaning, so that the problem that the residual photoresist is difficult to remove from the wafer due to the blocking of certain patterns during unidirectional rotation is solved.

Drawings

FIG. 1 is a schematic diagram illustrating a problem of development residue caused by unidirectional rotation of a wafer during rinsing after development.

Fig. 2 is a schematic diagram of some of the patterns that create a barrier to the photoresist on the wafer that needs to be removed.

FIG. 3 is a schematic view of a wafer rotating clockwise in the process of the present invention.

FIG. 4 is a schematic view of a wafer rotating in a counterclockwise direction during the process of the present invention.

FIG. 5 is a schematic diagram of the wafer rotating alternately in forward and reverse directions in the process of the present invention.

Detailed Description

The following detailed description of the present invention is provided with reference to the accompanying drawings, and the technical solutions in the present invention will be clearly and completely described, but the present invention is not limited to the following embodiments. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims. It is noted that the drawings are in greatly simplified form and that non-precision ratios are used for convenience and clarity only to aid in the description of the embodiments of the invention. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity, and the same reference numerals denote the same elements throughout. It will be understood that when an element or layer is referred to as being "on" …, "adjacent to …," "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on …," "directly adjacent to …," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

The method for eliminating the photoetching development residue comprises the steps of coating photoresist on a wafer after the wafer is cleaned and dried, carrying out exposure and baking after hardening, and then putting the wafer into a developing solution for developing. The photoresist can adopt positive photoresist or negative photoresist, the positive photoresist is the part which is not shielded by the mask plate after exposure and is then dissolved and removed in the developing solution, and the negative photoresist is the part which is not shielded by the mask plate after exposure and is then retained after the developing process. Therefore, the pattern on the mask used in the negative photoresist process is exactly the opposite of the pattern on the mask used in the positive photoresist process.

During developing, spraying a developing solution on the surface of the wafer, so that the developing solution and the exposed photoresist are subjected to full reaction, and the photoresist to be completely removed is subjected to full reaction with the developing solution; after the development is finished, washing the surface of the wafer to remove the photoresist which has undergone polymerization reaction; when the positive photoresist is used, the cleaning liquid is ultrapure water; when the negative photoresist is used, the cleaning solution is n-butyl acetate or other solvents.

During washing, the wafer bearing platform drives the wafer to alternately rotate clockwise and anticlockwise, cleaning liquid is sprayed on the wafer, and photoresist which needs to be removed on the wafer is removed.

The wafer bearing platform drives the wafer to alternately rotate clockwise and anticlockwise, and the wafer is accelerated to a stable rotating speed or a standard process rotating speed from a static state gradually in a clockwise direction and then is decelerated to the static state gradually. As shown in fig. 3, taking the positive photoresist as an example, when the wafer rotates clockwise, the enlarged view in the square box in the four corners area in the figure shows the states of the patterns in the four different positions during the developing process, and taking the square box in the upper left corner as an example, when the wafer rotates clockwise, the photoresist (dark solid block) needs to be thrown away from the wafer, although there is centrifugal force and washing of the rinsing agent, the photoresist is blocked on the wafer and is difficult to be thrown away due to the blocking of the right-angle pattern, and is blocked in the pattern, and cannot be thrown away until the clockwise rotation is completely stopped, thereby forming the developing residue. Similar problems may exist with other area graphics.

Then, the wafer is switched to the counterclockwise direction and then gradually accelerated to a stable rotation speed or a standard process rotation speed, as shown in fig. 4, when the wafer rotates counterclockwise, various acting forces are opposite to those when the wafer rotates clockwise, in the graph displayed by the upper left square box in fig. 3, photoresist which should fall off when the wafer rotates clockwise is blocked by the right-angle-shaped graph and cannot be separated from the surface of the wafer, when the wafer rotates counterclockwise, the direction of the acting force which is originally thrown away from the surface of the wafer is reverse, and the blocking of the photoresist by the original right-angle-shaped graph does not exist, as shown in the same graph in the upper left square box in fig. 4, compared with the clockwise direction in fig. 3, the photoresist is stressed in the opposite direction, the right-angle-shaped graph does not block the photoresist, and the residual photoresist is thrown away from the surface of the wafer, so that development residues are eliminated.

Subsequently, the wafer rotation speed is gradually decelerated to be still, and then the next process is repeated.

And completely removing the photoresist to be removed on the wafer through repeated positive and negative alternate rotation.

The invention aims at the problem of development residue in the development process after photoetching by alternately rotating the wafer clockwise and anticlockwise, and the development residue on the wafer can be shaken off the surface of the wafer by multidirectional impact force by alternately rotating the wafer in the forward and reverse directions during cleaning, thereby overcoming the problem that the residual photoresist is difficult to remove from the wafer due to the blocking of certain patterns during pure unidirectional rotation in the traditional process.

The above are merely preferred embodiments of the present invention, and are not intended to limit the present invention. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.