Method for improving developing process

Abstract

The invention discloses a method for improving a developing process, and the method comprises the following steps: enabling a wafer to rotate along a first direction, spraying deionized water right above the center of the surface of the wafer, and forming first covering liquid on the surface of the wafer; the speed of the wafer is reduced to zero; rotating the wafer along the first direction, and spraying a developing solution back and forth on the surface of the wafer from the center to the edge for multiple times; rotating the wafer along the first direction, and spraying a developing solution on the surface of the wafer from the edge to the center; rotating the wafer along a second direction, spraying a developing solution right above the center of the surface of the wafer, and forming a second covering solution on the surface of the wafer; enabling the photoresist and the second covering liquid to fully react in a circulating mode; and washing and spin-drying the wafer which is sprayed with the developing solution and subjected to the developing reaction. According to the invention, the film forming state after the developing process can be effectively improved, the uniformity of the developing line width is improved, the dosage of the developing solution can be reduced, and the production cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor integrated circuit processes, and in particular, to a method for improving a development process. Background Art

[0002] The conventional chip process flow is usually film coating, photoresist coating, exposure, development, etching, and photoresist stripping. However, for the lift-off process, the process flow is usually photoresist coating, exposure, development, film coating, and stripping. Compared with the conventional chip process flow, the lift-off process can reduce the etching process, greatly increase the production capacity, and reduce the cost. However, the lift-off process has high requirements for the cross-sectional photoresist structure (Profile) after development. The conventional chip process requires the topography of the photoresist after coating and development to be a top-cut shape; but for the lift-off process, the topography of the photoresist after coating and development is required to be a bottom-cut shape. Therefore, negative photoresist is usually used in the lift-off process. However, the negative photoresist has strong hydrophobicity on the surface and is extremely sensitive to the developer. Using the conventional development method, due to the hydrophobicity of the negative photoresist surface, the surface film-forming state is usually poor. Although increasing the spraying amount of the developer can improve this defect, the negative photoresist is sensitive to the developer and has a great impact on the critical dimension uniformity (CDU) of the pattern after the development process. The same problem also exists for positive photoresist.

[0003] Therefore, it is necessary to provide a method for improving the development process to solve the above problems existing in the prior art. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for improving the development process, which can effectively improve the film-forming state after the development process, improve the development critical dimension uniformity, and can reduce the usage amount of the developer, thereby reducing the production cost.

[0005] To achieve the above purpose, the technical solution of the present invention is as follows:

[0006] A method for improving the development process includes the following steps:

[0007] S0: Provide a wafer with a photoresist coated on the surface and subjected to an exposure process;

[0008] S1: Rotate the wafer along a first direction at a first rotation speed for a first preset time, and at the same time, spray deionized water on the wafer surface directly above the center of the wafer using a first nozzle;

[0009] S2: Rotate the wafer along the first direction at a second rotation speed for a second preset time, continue to spray deionized water on the wafer surface directly above the center of the wafer using the first nozzle, and form a first liquid film on the wafer surface;

[0010] S3: Rotate the wafer along the first direction at a third rotational speed for a third preset time;

[0011] S4: Rotate the wafer along the first direction at a fourth rotational speed for a fourth preset time, and at the same time, use the second nozzle to spray the developer solution on the surface of the wafer multiple times back and forth from its center to the edge at a first spraying rate;

[0012] S5: Rotate the wafer along the first direction at a fifth rotational speed for a fifth preset time, and at the same time, use the second nozzle to spray the developer solution on the surface of the wafer from its edge to the center at a second spraying rate;

[0013] S6: Rotate the wafer along the second direction at a sixth rotational speed for a sixth preset time, and at the same time, use the second nozzle to spray the developer solution directly above the center of the wafer surface at a third spraying rate to form a second liquid coating on the wafer surface;

[0014] S7: Make the photoresist and the second liquid coating react fully in a cyclic manner;

[0015] S8: Rinse and spin-dry the wafer after the development reaction of spraying the developer solution is completed;

[0016] Wherein, the first direction is opposite to the second direction.

[0017] It can be seen from the above technical solutions that the present invention sprays deionized water on the surface of the wafer at the first rotational speed, the second rotational speed and the third rotational speed before development to form a first liquid coating and does not spin-dry it as a buffer, reducing the concentration of the developer solution and improving the problem of uneven development caused by the difference in the reaction time between the water-repellent photoresist and the developer solution; at the same time, during the development film-forming process, the developer solution is sprayed on the surface of the wafer at the fourth rotational speed, the fifth rotational speed and the sixth rotational speed, and the wafer is formed with a second liquid coating in a combination of forward and reverse rotations, that is, a reverse low-speed rotation is added in the final stage of forming the second liquid coating of the developer solution. By using inertial contrast, the developer solution and the photoresist can fit better, greatly improving the film-forming problem of the developer solution on the surface of the water-repellent photoresist.

[0018] Further, the cyclic manner includes: first making the wafer stationary, then rotating the wafer along the first direction at a seventh rotational speed for a seventh preset time, then making the wafer stationary, and then rotating the wafer along the second direction at an eighth rotational speed for an eighth preset time.

[0019] As can be seen from the above technical solution, in the present invention, an intermittent dynamic development method is adopted during the development process for repeated cycling. The cycling method is as follows: first, the wafer is stationary, then the wafer rotates along the first direction at the seventh rotation speed for the seventh preset time, then the wafer is stationary again, and then the wafer rotates along the second direction at the eighth rotation speed for the eighth preset time. Through this cycling method, the developer and the photoresist are fully contacted, thereby ensuring that the developer and the photoresist react fully.

[0020] Further, in the step S1, the spraying flow rate of the first nozzle is 800 - 1200 ml / min, the first rotation speed is 100 - 500 r / min, and the first preset time is 2 - 10 s.

[0021] Further, the spraying flow rate of the first nozzle is 1000 ml / min, the first rotation speed is 200 r / min, and the first preset time is 5 s.

[0022] Further, in the step S2, the spraying flow rate of the first nozzle is 800 - 1200 ml / min, the second rotation speed is 5 - 50 r / min, and the second preset time is 0.1 - 20 s.

[0023] Further, the spraying flow rate of the first nozzle is 1000 ml / min, the second rotation speed is 15 r / min, and the second preset time is 17 s.

[0024] Further, in the step S3, the third rotation speed is 0 r / min, and the third preset time is 2 - 10 s.

[0025] Further, the third preset time is 6 s.

[0026] Further, in the step S4, the first spraying rate is 800 - 900 ml / min, and the speed at which the second nozzle moves back and forth is 150 - 300 mm / s. The number of times the second nozzle scans is once, three times, or five times. The fourth rotation speed is 50 - 300 r / min, and the fourth preset time is 3 - 15 s.

[0027] Further, the first spraying rate is 800 ml / min, and the speed at which the second nozzle moves back and forth is 240 mm / s. The number of times the second nozzle scans is three times. The fourth rotation speed is 100 r / min, and the fourth preset time is 4 s.

[0028] Further, in the step S5, the second spraying rate is 800 - 900 ml / min, the speed of the second nozzle for reciprocating movement is 5 - 50 mm / s, the number of scans of the second nozzle is one, three or five times, the fifth rotation speed is 10 - 50 r / min, and the fifth preset time is 8 - 24 s.

[0029] Further, the second spraying rate is 800 ml / min, the speed of the second nozzle for reciprocating movement is 30 mm / s, the number of scans of the second nozzle is three times, the fifth rotation speed is 15 r / min, and the fifth preset time is 18 s.

[0030] Further, in the step S6, the third spraying rate is 800 - 900 ml / min, the sixth rotation speed is 10 - 50 r / min, and the sixth preset time is 3 - 9 s.

[0031] Further, the third spraying rate is 800 ml / min, the sixth rotation speed is 15 r / min, and the sixth preset time is 4 s.

[0032] Further, the number of times of adopting the cyclic mode is N times, where N is a positive integer. Each time the cyclic mode includes: first making the wafer stationary for 5 s, then making the wafer rotate along the first direction at a speed of 10 - 30 r / min for 2 s, then making the wafer stationary for 5 s, and then making the wafer rotate along the second direction at a speed of 10 - 30 r / min for 2 s.

[0033] Further, the number of times of adopting the cyclic mode is 6 times. Each time the cyclic mode includes: first making the wafer stationary for 5 s, then making the wafer rotate along the first direction at a speed of 20 r / min for 2 s, then making the wafer stationary for 5 s, and then making the wafer rotate along the second direction at a speed of 20 r / min for 2 s.

[0034] Further, the step S8 includes:

[0035] S81: Making the wafer rotate along the first direction, and simultaneously spraying deionized water on the surface of the wafer using the first nozzle;

[0036] S82: Stopping spraying deionized water, and then increasing the rotation speed of the wafer to spin - dry the wafer.

[0037] Further, in the step S81, the spraying flow rate of the first nozzle is 800 - 1200 ml / min, and the rotation speed of the wafer is 500 - 2000 r / min.

[0038] Further, the spraying flow rate of the first nozzle is 1000 ml / min, and the rotation speed of the wafer is 1200 r / min.

[0039] Further, in step S82, the rotation speed of the wafer is 2000 r / min, and the rotation time of the wafer is 25 s.

[0040] Further, the thickness of the photoresist film formed on the wafer surface is 5 - 15 μm.

[0041] Further, between step S4 and step S5, the following steps are further included:

[0042] S4a: Rotate the wafer along the first direction at a fifth rotation speed for a ninth preset time, and at the same time, use the second nozzle to spray the developer at a fixed point on the edge of the wafer surface at a fourth spraying rate;

[0043] Between step S6 and step S7, the following steps are further included:

[0044] S6a: Rotate the wafer along the second direction at a sixth rotation speed for a tenth preset time, and at the same time, use the second nozzle to spray the developer at a fixed point directly above the center of the wafer surface at a fifth spraying rate.

[0045] Further, the fourth spraying rate is 800 ml / min, the fifth rotation speed is 15 r / min, and the ninth preset time of the wafer is 4 s; the fifth spraying rate is 800 ml / min, the sixth rotation speed is 15 r / min, and the tenth preset time is 1 s.

[0046] Further, in step S5, the second spraying rate is 800 ml / min, the speed of the second nozzle for reciprocating movement is 25 mm / s, the number of scans of the second nozzle is three times, the fifth rotation speed is 15 r / min, and the fifth preset time is 18 s.

[0047] It can be seen from the above technical solutions that the present invention can reduce the spraying times and time of the developer, thereby reducing the consumption of the developer, and reducing the spraying time of the developer in the central area of the wafer. While reducing the consumption of the developer, the line width uniformity is improved. Therefore, the present invention can effectively improve the film formation state after the developing process, improve the developing line width uniformity, and can reduce the consumption of the developer, reducing the production cost. Description of the Drawings

[0048] Figure 1 It is a flowchart of the method for improving the developing process according to an embodiment of the present invention. Detailed Embodiments

[0049] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings as understood by those of ordinary skill in the art to which the present invention pertains. The words such as "including" used herein mean that the elements or items appearing before this word cover the elements or items listed after this word and their equivalents, without excluding other elements or items.

[0050] The following further elaborates on the specific implementation manners of the present invention with reference to the accompanying drawings.

[0051] As Figure 1 shown, the embodiments of the present invention provide a method for improving the development process, including the following steps:

[0052] Step S0: Provide a wafer with a photoresist coated on its surface and subjected to an exposure process.

[0053] Step S1: Rotate the wafer in a first direction at a first rotation speed for a first preset time, and at the same time, use a first nozzle to spray deionized water directly above the center of the wafer surface.

[0054] In some embodiments of the present invention, the first nozzle sprays deionized water (DIW). The first direction is, for example, the counterclockwise direction. In step S1, the spraying flow rate of the first nozzle is 800 - 1200 ml / min, the first rotation speed is 100 - 500 r / min, and the first preset time is 2 - 10 s. This is used to wet the surface of the photoresist, thereby changing the hydrophilicity of the photoresist surface.

[0055] Step S2: Rotate the wafer in the first direction at a second rotation speed for a second preset time, continue to use the first nozzle to spray deionized water directly above the center of the wafer surface, and form a first liquid film on the wafer surface.

[0056] In some embodiments of the present invention, in step S2, the spraying flow rate of the first nozzle is 800 - 1200 ml / min, the second rotation speed is 5 - 50 r / min, and the second preset time is 0.1 - 20 s. By spraying deionized water to form a first liquid film without spin-drying as a buffer, the concentration of the developer is reduced, and the problem of uneven development caused by the difference in the reaction time between the hydrophobic photoresist and the developer is improved.

[0057] Step S3: Rotate the wafer in the first direction at a third rotation speed for a third preset time.

[0058] In some embodiments of the present invention, in step S3, the third rotation speed is 0 r / min, and the third preset time is 2 to 10 s. That is to say, the wafer at the second rotation speed is decelerated to 0, and no spin-drying is performed. At this time, the rotation time is 2 to 10 s. Thus, a first liquid coating with a certain thickness is uniformly covered on the surface of the photoresist.

[0059] By using deionized water to form a first liquid coating (Puddle) before spraying the developer, the deionized water on the wafer surface can play a buffering role after spraying the developer, reducing the surface differences of the wafer, thereby further improving the critical dimension uniformity (CDU).

[0060] Step S4: Rotate the wafer along the first direction at a fourth rotation speed for a fourth preset time, and at the same time, use the second nozzle to spray the developer on the wafer surface multiple times back and forth along the direction from its center to the edge at a first spraying rate.

[0061] In some embodiments of the present invention, the second nozzle sprays the developer. The second nozzle is an H-Nozzle, but is not limited to the H-Nozzle, and other nozzles similar to the H-Nozzle type are also applicable. And the second nozzle sprays the developer in a scanning manner. In step S4, the first spraying rate is 800 to 900 ml / min, the speed of the second nozzle for reciprocating movement is 150 to 300 mm / s, the number of scans of the second nozzle is one or three or five, the fourth rotation speed is 50 to 300 r / min, and the fourth preset time is 3 to 15 s. This step preliminarily treats the surface of the photoresist by repeatedly and dynamically moving the second nozzle to spray the developer quickly, improving the hydrophilicity of the photoresist surface.

[0062] Step S5: Rotate the wafer along the first direction at a fifth rotation speed for a fifth preset time, and at the same time, use the second nozzle to spray the developer on the wafer surface along the direction from its edge to the center at a second spraying rate.

[0063] In some embodiments of the present invention, in step S5, the second spraying rate is 800 to 900 ml / min, the speed of the second nozzle for reciprocating movement is 5 to 50 mm / s, the number of scans of the second nozzle is one or three or five, the fifth rotation speed is 10 to 50 r / min, and the fifth preset time is 8 to 24 s. This step sprays the developer by moving the second nozzle slowly, so that the developer is sprayed on the wafer.

[0064] Step S6: Rotate the wafer along the second direction at a sixth rotation speed for a sixth preset time, and at the same time, use the second nozzle to spray the developer at a third spraying rate directly above the center of the wafer surface to form a second liquid coating on the wafer surface.

[0065] In some embodiments of the present invention, the second direction is opposite to the first direction, and the first direction is, for example, counterclockwise, and the second direction is clockwise. In step S6, the third spraying rate is 800-900 ml / min, the sixth rotation speed is 10-50 r / min, and the sixth preset time is 3-9 s. The developer is sprayed on the center of the wafer by the second nozzle moving slowly, so that the developer is coated on the wafer, thereby forming a second coating.

[0066] By adding reverse low-speed rotation in the final stage of the developer forming the second covering liquid (Puddle), that is, rotating the wafer in the reverse direction while spraying the developer, the developer above the photoresist still rotates in the original direction due to inertia, so that the hydrophobic photoresist on the wafer surface forms a contrast with the developer, and the developer and the photoresist can better fit, which greatly improves the film-forming state of the developer on the hydrophobic photoresist surface.

[0067] Step S7: using a circulation method to allow the photoresist to fully react with the second covering liquid.

[0068] In some embodiments of the present invention, after the second coating liquid is formed, an intermittent dynamic development method is used for development, relative to a static development method, that is, the wafer is intermittently rotated, and the cycle of the wafer is a process of stationary-rotating. Specifically, this cycle includes: first making the wafer stationary, then rotating the wafer along the first direction at a seventh speed for a seventh preset time, then making the wafer stationary, and then rotating the wafer along the second direction at an eighth speed for an eighth preset time. In this way, the photoresist is fully in contact with the developer and fully reacts.

[0069] In some embodiments of the present invention, the number of cycles is N, where N is a positive integer. The number of cycles is set according to the final required line width (CD). Each cycle includes: first, the wafer is kept still for 5 seconds, then the wafer is rotated along the first direction at a speed of 10 to 30 r / min for 2 seconds, then the wafer is kept still for 5 seconds, and then the wafer is rotated along the second direction at a speed of 10 to 30 r / min for 2 seconds. This cycle is repeated N times.

[0070] By adopting a dynamic Puddle development method and combining counterclockwise and clockwise rotation for development, the developer is in full contact with the photoresist, thereby enabling full reaction.

[0071] Step S8: Rinse and dry the wafer after the developer is sprayed and the development reaction is completed.

[0072] In some embodiments of the present invention, step S8 includes:

[0073] S81: rotating the wafer along the first direction, and spraying deionized water on the surface of the wafer using a first nozzle.

[0074] In some embodiments of the present invention, in step S81, the spraying flow rate of the first nozzle is 800 - 1200 ml / min, and the rotation speed of the wafer is 500 - 2000 r / min. In this step, deionized water is sprayed to wash away the developer and reaction residues.

[0075] S82: Stop spraying deionized water, and then increase the rotation speed of the wafer to spin-dry the wafer.

[0076] In some embodiments of the present invention, in step S82, the rotation speed of the wafer is 2000 r / min, and the rotation time of the wafer is 25 s. In this step, the wafer is spin-dried by means of high-speed rotation of the wafer.

[0077] In some embodiments of the present invention, the thickness of the photoresist film coated on the wafer surface is 5 - 15 μm.

[0078] In some embodiments of the present invention, the two steps of spraying the developer at fixed points on the wafer edge and spraying the developer at fixed points in the wafer center can be added, and the moving speed of the second nozzle in step S5 can be adjusted, so as to freely adjust the critical dimension uniformity (CDU) according to different film thickness conditions and different wafer warping conditions, as follows:

[0079] Between step S4 and step S5, the following steps are further included:

[0080] S4a: Rotate the wafer along the first direction at the fifth rotation speed for the ninth preset time, and at the same time, use the second nozzle to spray the developer at a fixed point on the edge of the wafer surface at the fourth spraying rate;

[0081] Between step S6 and step S7, the following steps are further included:

[0082] S6a: Rotate the wafer along the second direction at the sixth rotation speed for the tenth preset time, and at the same time, use the second nozzle to spray the developer at a fixed point directly above the center of the wafer surface at the fifth spraying rate.

[0083] In some embodiments of the present invention, the fourth spraying rate is 800 ml / min, the fifth rotation speed is 15 r / min, and the ninth preset time of the wafer is 4 s. Thereby, the line width at the wafer edge is adjusted.

[0084] In some embodiments of the present invention, the fifth spraying rate is 800 ml / min, the sixth rotation speed is 15 r / min, and the tenth preset time is 1 s. Thereby, the line width at the wafer center is adjusted.

[0085] Specifically, Example 1:

[0086] For example, a negative photoresist with a film thickness of 10 μm is coated on the wafer, and after exposure treatment, the development process includes the following steps:

[0087] Step S1: The wafer rotates counterclockwise at a speed of 200 r / min for 5 s. Meanwhile, deionized water is sprayed onto the center of the wafer surface directly above at a spraying flow rate of 1000 ml / min using the first nozzle.

[0088] Step S2: The wafer rotates counterclockwise at a speed of 15 r / min for 17 s. At the same time, deionized water continues to be sprayed onto the center of the wafer surface directly above at a spraying flow rate of 1000 ml / min using the first nozzle, forming a first puddle on the wafer surface.

[0089] Step S3: After the deionized water forms a puddle, the rotation speed of the wafer is reduced to 0 and it rotates for 6 s.

[0090] Step S4: The wafer rotates counterclockwise at 100 r / min for 4 s. Meanwhile, the developing solution is sprayed onto the wafer surface three times back and forth from the center to the edge at a spraying rate of 800 ml / min using the scanning second nozzle, and the moving speed of the scanning second nozzle is 240 mm / s.

[0091] Step S5: The wafer rotates counterclockwise at 15 r / min for 18 s. At the same time, the developing solution is sprayed onto the wafer surface three times back and forth from the edge to the center at a spraying rate of 800 ml / min using the scanning second nozzle, and the moving speed of the scanning second nozzle is 30 mm / s (after the scanning second nozzle sprays the developing solution at a moving speed of 30 mm / s for 15 s, it stays at the center of the wafer for 3 s).

[0092] Step S6: The wafer rotates clockwise at 15 r / min for 4 s. Meanwhile, the developing solution is sprayed onto the center of the wafer surface directly above at a spraying rate of 800 ml / min using the scanning second nozzle, forming a second puddle on the wafer surface.

[0093] Step S7: After the developing solution forms a puddle, first keep the wafer stationary for 5 s, then rotate the wafer counterclockwise at a speed of 20 r / min for 2 s, then keep the wafer stationary for 5 s, and then rotate the wafer clockwise at a speed of 20 r / min for 2 s. This dynamic developing method is cycled six times.

[0094] Step S8: The wafer rotates counterclockwise at a speed of 1200 r / min. Meanwhile, deionized water is sprayed at a fixed point on the center of the wafer surface at a spraying flow rate of 1000 ml / min using the first nozzle for rinsing.

[0095] Step S9: After stopping the spraying of deionized water, the wafer rotates counterclockwise at a high speed of 2000 r / min for 25 s to perform spin-drying.

[0096] After developing according to the above developing process, the surface of the wafer was observed using an optical microscope. The photoresist had a uniform color, no color difference, and no abnormal conditions such as liquid marks on the surface. The film formation state during the developing puddle process was good. After developing, the wafer was measured at 49 points in a cross pattern using a critical dimension scanning electron microscope (CDSEM). The average value of the critical dimension (CD) was 36.6 μm, the CD Range (the maximum value of CD minus the minimum value of CD) was 3.16 μm, the CD at the center of the wafer was 38.7 μm, the CD at the Mid position of the wafer (i.e., the midpoint area between the center and the edge of the wafer) was 37.53 μm, and the CD at the edge of the wafer was 35.55 μm. The consumption of the developer was 347 ml.

[0097] It can be seen that by using the developing process of Example 1, deionized water was used to form the first puddle before spraying the developer, and the deionized water on the surface of the wafer could play a buffering role after spraying the developer; at the same time, reverse low-speed rotation was added at the final stage of forming the second puddle of the developer, that is, the wafer was rotated in the reverse direction while spraying the developer. Due to inertia, the developer above the negative photoresist still rotated in the original direction. In this way, the water-repellent negative photoresist on the surface of the wafer formed a contrast with the developer, and the developer and the photoresist could fit better, greatly improving the film formation state of the developer on the surface of the water-repellent negative photoresist; and a dynamic puddle developing method was adopted, and the developing was carried out in a combination of counterclockwise and clockwise rotation directions, enabling the developer to fully contact the negative photoresist, so that they could fully react, improving the line width uniformity, reducing the consumption of the developer, and lowering the production cost.

[0098] Specifically, Example 2:

[0099] For example, a negative photoresist with a film thickness of 10 μm was coated on the wafer, and after exposure treatment, the developing process included the following steps:

[0100] Step S1: The wafer was rotated at a speed of 200 r / min in the counterclockwise direction for 5 s. At the same time, deionized water was sprayed at a spraying flow rate of 1000 ml / min directly above the center of the wafer surface using the first nozzle.

[0101] Step S2: The wafer was rotated at a speed of 15 r / min in the counterclockwise direction for 17 s, and at the same time, the first nozzle continued to spray deionized water at a spraying flow rate of 1000 ml / min directly above the center of the wafer surface to form the first puddle on the wafer surface.

[0102] Step S3: After the deionized water formed a puddle, the rotation speed of the wafer was reduced to 0 and rotated for 6 s.

[0103] Step S4: The wafer rotates counterclockwise at 100 r / min for 4 s. Meanwhile, the developing solution is sprayed onto the wafer surface three times back and forth from its center to the edge at a spraying rate of 800 ml / min by using a scanning second nozzle, and the moving speed of the scanning second nozzle is 240 mm / s.

[0104] Step S4a: The wafer rotates counterclockwise at 15 r / min for 4 s. Meanwhile, the developing solution is sprayed onto a fixed point at the edge of the wafer surface at a spraying rate of 800 ml / min by using a second nozzle.

[0105] Step S5: The wafer rotates counterclockwise at 15 r / min for 18 s. Meanwhile, the developing solution is sprayed onto the wafer surface three times back and forth from its edge to the center at a spraying rate of 800 ml / min by using a scanning second nozzle, and the moving speed of the scanning second nozzle is 25 mm / s (the scanning second nozzle sprays the developing solution for 18 s at a moving speed of 25 mm / s).

[0106] Step S6: The wafer rotates clockwise at 15 r / min for 4 s. Meanwhile, the developing solution is sprayed onto the wafer surface directly above the center at a spraying rate of 800 ml / min by using a scanning second nozzle.

[0107] Step S6a: The wafer rotates clockwise at 15 r / min for 1 s. Meanwhile, the developing solution is sprayed onto a fixed point directly above the center of the wafer surface at a spraying rate of 800 ml / min by using a second nozzle.

[0108] Step S7: First, the wafer is stationary for 5 s, then it rotates along the first direction at 20 r / min for 2 s, then it is stationary for 5 s again, and then it rotates along the second direction at 20 r / min for 2 s. This dynamic developing method is cycled six times.

[0109] Step S8: The wafer rotates counterclockwise at 1200 r / min. Meanwhile, deionized water is sprayed onto the center of the wafer surface at a spraying flow rate of 1000 ml / min by using a first nozzle for rinsing.

[0110] Step S9: After stopping the spraying of deionized water, the wafer rotates at a high speed of 2000 r / min counterclockwise for 25 s to perform spin-drying.

[0111] After development is completed according to the above development process, the surface of the wafer is observed using an optical microscope. The photoresist color is uniform, there is no color difference, and there are no abnormalities such as liquid marks on the surface. The film formation state is good during the development puddle process. After development, the wafer is measured at 49 points in a cross pattern using a critical dimension scanning electron microscope (CDSEM). The average value of the critical dimension (CD) is 38.05 μm, the CD Range (the maximum value of CD minus the minimum value of CD) is 2 μm, the CD at the center of the wafer is 39 μm, the CD at the Mid position of the wafer (i.e., the midpoint area between the center and the edge of the wafer) is 38.53 μm, and the CD at the edge of the wafer is 37 μm. It can meet the mass production requirements, and the consumption of the developer is 413 ml.

[0112] Thus, by adding the two steps of step S4a and step S6a and adjusting the moving speed of the scanning second nozzle in step S5, the uniformity of the critical dimension (line width) can be freely adjusted according to different film thickness conditions and different warping conditions of the wafer.

[0113] To fully illustrate the present invention, four comparative examples are specifically listed for comparative description.

[0114] Comparative Example 1:

[0115] For example, a negative photoresist with a film thickness of 10 μm is coated on the wafer. The development process includes the following steps:

[0116] (1) The wafer rotates counterclockwise at a speed of 100 r / min for 4 s, and at the same time, a scanning second nozzle sprays the developer three times back and forth on the surface of the wafer from its center to the edge at a spraying rate of 800 ml / min, and the moving speed of the scanning second nozzle is 240 mm / s;

[0117] (2) The wafer rotates counterclockwise at a speed of 15 r / min for 18 s, and at the same time, a scanning second nozzle sprays the developer three times back and forth on the surface of the wafer from its edge to the center at a spraying rate of 800 ml / min, and the moving speed of the scanning second nozzle is 30 mm / s;

[0118] (3) The wafer rotates clockwise at 15 r / min for 4 s, and at the same time, a scanning second nozzle sprays the developer at a spraying rate of 800 ml / min directly above the center of the wafer surface to coat the developer on the wafer to form a puddle;

[0119] (4) After the developer is coated on the wafer, first make the wafer stand still for 5 s, then make the wafer rotate counterclockwise at a speed of 20 r / min for 2 s, then make the wafer stand still for 5 s again, and then make the wafer rotate clockwise at a speed of 20 r / min for 2 s, and so on for 6 cycles;

[0120] (5) The wafer rotates counterclockwise at a speed of 1200 r / min, and deionized water is sprayed at a flow rate of 1000 ml / min at a fixed point in the center of the wafer using the first nozzle to rinse off the developer and reaction residues;

[0121] (6) The wafer rotates counterclockwise at a high speed of 2000 r / min for 25 s for spin-drying.

[0122] After development is completed according to the above development process, the surface of the wafer is observed using an optical microscope. The surface is abnormal with serious color difference. The film-forming state is good during the puddle process of the developer. After development, the wafer is measured at 49 cross points using a critical dimension scanning electron microscope (CDSEM). The average value of the critical dimension (CD) is 41 μm, and the CD Range (the maximum value of CD minus the minimum value of CD) is 11 μm. The consumption of the developer is 347 ml.

[0123] It can be seen that omitting the key step of first spraying deionized water on the wafer to form a puddle results in abnormal surface of the wafer after development, serious color difference on the photoresist surface, poor film-forming state, and uneven critical dimension (line width), etc. This shows the importance of deionized water puddle in the development process.

[0124] Comparative Example 2:

[0125] For example, a negative photoresist with a film thickness of 10 μm is coated on the wafer. The development process includes the following steps:

[0126] (1) The wafer rotates counterclockwise at a speed of 200 r / min for 5 s, and at the same time, deionized water is sprayed at a flow rate of 1000 ml / min at the center of the wafer surface using the first nozzle;

[0127] (2) The wafer rotates counterclockwise at a speed of 15 r / min for 17 s, and at the same time, deionized water is continuously sprayed at a flow rate of 1000 ml / min at the center of the wafer surface using the first nozzle to uniformly cover the surface of the negative photoresist with deionized water to form the first puddle;

[0128] (3) After the deionized water forms a puddle, the rotation speed of the wafer is reduced to 0 and rotated for 6 s;

[0129] (4) The wafer rotates counterclockwise at a speed of 100 r / min for 4 s, and at the same time, the second nozzle sprays the developer three times back and forth along the center to the edge of the wafer surface at a spraying rate of 800 ml / min, and the moving speed of the scanning second nozzle is 240 mm / s;

[0130] (5) The wafer rotates counterclockwise at 15 r / min for 18 s, and the developing solution is sprayed three times back and forth on the wafer surface from its edge to the center at a spraying rate of 800 ml / min using a scanning second nozzle, and the moving speed of the scanning second nozzle is 30 mm / s;

[0131] (6) The wafer rotates clockwise at 15 r / min for 4 s, and at the same time, the developing solution is sprayed on the wafer surface directly above the center at a spraying rate of 800 ml / min using a scanning second nozzle to coat the developing solution on the wafer and form a second puddle;

[0132] (7) After the developing solution is coated on the wafer, static development is carried out, and the development time is 84 s;

[0133] (8) The wafer rotates counterclockwise at 1200 r / min, and at the same time, deionized water is sprayed at a fixed point on the wafer surface at the center at a spraying rate of 1000 ml / min using the first nozzle for rinsing;

[0134] (9) The wafer rotates at a high speed of 2000 r / min counterclockwise for 25 s for spin-drying.

[0135] After the development is completed according to the above development process, the surface of the wafer is observed using an optical microscope. The negative photoresist has a uniform color, no color difference, and no abnormal liquid marks on the surface. The film formation state is good during the development puddle process. The developed wafer is measured at 49 points in a cross shape using a critical dimension scanning electron microscope (CDSEM). The average value of the critical dimension (CD) is 36.6 μm, and the CDRange (the maximum value of CD minus the minimum value of CD) is 3.5 μm. The consumption of the developing solution is 347 ml.

[0136] It can be seen that compared with the intermittent dynamic development method, the static development method has a poorer critical dimension (line width) uniformity, and the dynamic development method can make the reaction between the developing solution and the negative photoresist more sufficient.

[0137] Control Example Three:

[0138] For example, a negative photoresist with a film thickness of 10 μm is coated on the wafer, and the development process includes the following steps:

[0139] (1) The wafer rotates counterclockwise at a speed of 200 r / min for 5 s, and at the same time, deionized water is sprayed on the wafer surface at the center at a spraying flow rate of 1000 ml / min using the first nozzle;

[0140] (2) The wafer rotates counterclockwise at a speed of 15 r / min for 17 s. Meanwhile, deionized water is continuously sprayed onto the center of the wafer surface at a spraying flow rate of 1000 ml / min using the first nozzle, so that the deionized water evenly covers the surface of the negative photoresist, forming a puddle.

[0141] (3) After the deionized water forms a puddle, the rotation speed of the wafer is reduced to 0 and it rotates for 6 s.

[0142] (4) The wafer rotates counterclockwise at a speed of 300 r / min for 40 s. Meanwhile, the second nozzle sprays the developer solution forty times back and forth along the center to the edge of the wafer surface at a spraying rate of 800 ml / min, and the moving speed of the scanning second nozzle is 150 mm / s.

[0143] (5) The wafer rotates counterclockwise at a speed of 1200 r / min. Meanwhile, deionized water is sprayed at a fixed point on the center of the wafer surface at a spraying flow rate of 1000 ml / min using the first nozzle for rinsing to wash away the developer solution and reaction residues.

[0144] (6) The wafer rotates at a high speed of 2000 r / min counterclockwise for 25 s for spin-drying.

[0145] After the development is completed according to the above development process, the surface of the wafer is observed using an optical microscope. The photoresist color is uniform, there is no color difference, and there are no abnormal conditions such as liquid marks on the surface. The developed wafer is measured at 49 points in a cross shape using a critical dimension scanning electron microscope (CDSEM). The average value of the critical dimension (CD) is 37.1 μm, and the CD Range (the maximum value of CD minus the minimum value of CD) is 4.3 μm. The consumption of the developer solution is 533 mL.

[0146] It can be seen that using the development process of Comparative Example 3, due to the continuous spraying of the developer solution by the scanning second nozzle and repeated scanning, the consumption of the developer solution is extremely large, and the developer solution is developed in a way that does not form a puddle, resulting in poor uniformity of the critical dimension (line width).

[0147] Comparative Example 4:

[0148] For example, a negative photoresist (negative photoresist) with a film thickness of 10 μm is coated on the wafer. This development process includes the following steps:

[0149] (1) The wafer rotates counterclockwise at a speed of 200 r / min for 5 s. Meanwhile, deionized water is sprayed onto the center of the wafer surface at a spraying flow rate of 1000 ml / min using the first nozzle for pre-wetting.

[0150] (2) The wafer is rotated counterclockwise at a speed of 15 r / min for 17 s, and deionized water is continuously sprayed at the center of the wafer surface using the first nozzle at a spraying flow rate of 1000 ml / min, so that the deionized water evenly covers the surface of the negative photoresist to form a puddle;

[0151] (3) After the deionized water forms a Puddle, the wafer rotation speed is reduced to 0 and rotated for 6 seconds;

[0152] (4) The wafer is rotated counterclockwise at a speed of 100 r / min for 4 s, and at the same time, the second nozzle sprays the developer three times from the center to the edge of the wafer surface at a spraying rate of 800 ml / min, and the moving speed of the scanning second nozzle is 240 mm / s;

[0153] (5) The wafer is rotated counterclockwise at a speed of 15 r / min for 25 s, and the developer is sprayed on the surface of the wafer along its edge to the center at a spray rate of 800 ml / min using a scanning second nozzle. When the developer stays at the center of the wafer, the developer is continuously sprayed to form a Puddle;

[0154] (6) After the wafer forms a puddle, it is left to stand without rotation or liquid spraying, and the standing time is 84 seconds;

[0155] (7) The wafer is rotated in a counterclockwise direction at 1200 r / min, and deionized water is sprayed at a fixed point at the center of the wafer surface at a spray flow rate of 1000 ml / min using the first nozzle for rinsing;

[0156] (8) The wafer is rotated counterclockwise at 2000 r / min for 25 s to dry.

[0157] After the development is completed according to the above development process, the wafer surface is observed using an optical microscope. The photoresist color is uniform, there is no color difference, and there is no liquid mark on the surface. The film formation state of the development puddle process is relatively extreme. The developed wafer is measured using a critical dimension scanning electron microscope (CDSEM). The average value of the critical dimension (CD) is 36.7μm, the CD Range (the maximum value of CD minus the minimum value of CD) is 3.8μm, the CD of the wafer center is 39.5μm, the CD of the wafer Mid position (i.e. the midpoint area between the center and edge of the wafer) is 36.3μm, and the CD of the wafer edge is 35.7μm. The developer consumption is 380mL.

[0158] It can be seen that when using the development process of Comparative Example 4, due to the water repellency of the negative photoresist, the film-forming state on the surface is poor. Although increasing the spraying amount of the developer can improve this defect, the negative photoresist is sensitive to the developer, which will cause a larger critical dimension (line width) in the central area of the wafer and have a greater impact on the uniformity of the critical dimension (line width).

[0159] Through the comparison between Specific Embodiment 1 and Embodiment 2 of the present invention and Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4, after development according to the present invention, the film-forming state is better, the surface state is better, the uniformity of the critical dimension (line width) is improved, and the usage amount of the developer is reduced, thus reducing the production cost.

[0160] When using a positive photoresist for development, it is the same as above and will not be elaborated here.

[0161] In summary, the present invention sprays deionized water on the wafer surface at the first rotation speed, the second rotation speed and the third rotation speed before development to form a first liquid covering and does not spin-dry it as a buffer, which reduces the concentration of the developer and improves the problem of uneven development caused by the difference in the reaction time between the water-repellent photoresist and the developer; meanwhile, during the film-forming process of development, the developer is sprayed on the wafer surface at the fourth rotation speed, the fifth rotation speed and the sixth rotation speed and the wafer adopts a combination of forward and reverse rotations to form a second liquid covering, that is, a reverse low-speed rotation is added in the final stage of forming the second liquid covering of the developer. By using inertial contrast, the developer and the photoresist can fit better, greatly improving the film-forming problem of the developer on the surface of the water-repellent photoresist; and it is designed to use an intermittent dynamic development method for repeated circulation during development, and the circulation method is: first make the wafer stationary, then make the wafer rotate along the first direction at the seventh rotation speed for the seventh preset time, then make the wafer stationary, and then make the wafer rotate along the second direction at the eighth rotation speed for the eighth preset time. Through this circulation method, the developer and the photoresist are in full contact, so as to ensure that the developer and the photoresist react fully, which can effectively improve the film-forming state after the development process, improve the development line width uniformity, and can reduce the usage amount of the developer, thus reducing the production cost.

[0162] Although the embodiments of the present invention have been described in detail above, it is obvious to those skilled in the art that various modifications and changes can be made to these embodiments. However, it should be understood that such modifications and changes all fall within the scope and spirit of the present invention described in the claims. Moreover, the present invention described herein can have other embodiments and can be implemented or realized in various ways.

Claims

1. A method for improving a developing process, characterized in that, The following steps are involved: S0: Provide a wafer with a surface coated with photoresist and subjected to exposure processing; S1: rotating the wafer along a first direction at a first speed for a first preset time, and spraying deionized water using a first nozzle directly above the center of the wafer surface; S2: rotating the wafer along the first direction at a second speed for a second preset time, and continuing to spray deionized water using the first nozzle directly above the center of the wafer surface to form a first coating liquid on the wafer surface; S3: rotating the wafer along the first direction at a third speed for a third preset time; S4: rotating the wafer along the first direction at a fourth speed for a fourth preset time, and spraying the developer back and forth multiple times on the surface of the wafer along the center to the edge thereof at a first spraying rate using a second nozzle; S5: rotating the wafer along the first direction at a fifth rotation speed for a fifth preset time, and spraying the developer on the surface of the wafer along the edge to the center thereof at a second spraying rate using the second nozzle; S6: rotating the wafer along the second direction at a sixth speed for a sixth preset time, and spraying the developer at a third spraying rate using the second nozzle just above the center of the wafer surface to form a second coating on the wafer surface; S7: using a circulation method to allow the photoresist to fully react with the second coating liquid; S8: rinsing and drying the wafer after the developer reaction is completed after being sprayed with the developer; The first direction is opposite to the second direction.

2. The method for improving the development process according to claim 1, wherein, The cycle method includes: first making the wafer still, then rotating the wafer along the first direction at a seventh speed for a seventh preset time, then making the wafer still, and then rotating the wafer along the second direction at an eighth speed for an eighth preset time.

3. The method for improving the development process according to claim 1, wherein, In the step S1, the spraying flow rate of the first nozzle is 800-1200 ml / min, the first rotation speed is 100-500 r / min, and the first preset time is 2-10 s.

4. The method for improving the development process according to claim 3, wherein The spraying flow rate of the first nozzle is 1000 ml / min, the first rotation speed is 200 r / min, and the first preset time is 5 s.

5. The method for improving the developing process according to claim 1, wherein, In the step S2, the spraying flow rate of the first nozzle is 800-1200 ml / min, the second rotation speed is 5-50 r / min, and the second preset time is 0.1-20 s.

6. The method for improving the development process according to claim 5, wherein, The spraying flow rate of the first nozzle is 1000 ml / min, the second rotation speed is 15 r / min, and the second preset time is 17 s.

7. The method for improving the development process according to claim 1, characterized in that, In the step S3, the third rotation speed is 0 r / min, and the third preset time is 2 to 10 s.

8. The method for improving the development process according to claim 7, characterized in that, The third preset time is 6s.

9. The method for improving the development process according to claim 1, wherein In step S4, the first spraying rate is 800-900 ml / min, the reciprocating speed of the second nozzle is 150-300 mm / s, the second nozzle scans once, three times or five times, the fourth rotation speed is 50-300 r / min, and the fourth preset time is 3-15 s.

10. The method for improving the development process according to claim 9, wherein The first spraying rate is 800 ml / min, the speed at which the second nozzle moves back and forth is 240 mm / s, the number of times the second nozzle scans is three times, the fourth rotation speed is 100 r / min, and the fourth preset time is 4 s.

11. The method for improving the development process according to claim 1, characterized in that, In step S5, the second spraying rate is 800 - 900 ml / min, the speed at which the second nozzle moves back and forth is 5 - 50 mm / s, the number of times the second nozzle scans is one or three or five times, the fifth rotation speed is 10 - 50 r / min, and the fifth preset time is 8 - 24 s.

12. The method for improving the developing process according to claim 11, wherein, The second spraying rate is 800 ml / min, the speed at which the second nozzle moves back and forth is 30 mm / s, the number of times the second nozzle scans is three times, the fifth rotation speed is 15 r / min, and the fifth preset time is 18 s.

13. The method for improving the developing process according to claim 1, wherein, In step S6, the third spraying rate is 800 - 900 ml / min, the sixth rotation speed is 10 - 50 r / min, and the sixth preset time is 3 - 9 s.

14. The method for improving the development process according to claim 13, wherein The third spraying rate is 800 ml / min, the sixth rotation speed is 15 r / min, and the sixth preset time is 4 s.

15. The method for improving the development process according to claim 2, wherein, The number of times the cycle mode is adopted is N times, where N is a positive integer. Each cycle mode includes: first, keeping the wafer stationary for 5 s, then rotating the wafer along the first direction at a speed of 10 - 30 r / min for 2 s, then keeping the wafer stationary for 5 s, and then rotating the wafer along the second direction at a speed of 10 - 30 r / min for 2 s.

16. The method for improving the development process according to claim 15, characterized in that, The number of times the cycle mode is adopted is 6 times. Each cycle mode includes: first, keeping the wafer stationary for 5 s, then rotating the wafer along the first direction at a speed of 20 r / min for 2 s, then keeping the wafer stationary for 5 s, and then rotating the wafer along the second direction at a speed of 20 r / min for 2 s.

17. The method for improving the development process according to claim 1, characterized in that, Step S8 includes: S81: Rotate the wafer along the first direction, and at the same time, use the first nozzle to spray deionized water on the surface of the wafer; S82: Stop spraying deionized water, and then increase the rotation speed of the wafer to spin-dry the wafer.

18. The method for improving the development process according to claim 17, characterized in that, In step S81, the spraying flow rate of the first nozzle is 800 - 1200 ml / min, and the rotation speed of the wafer is 500 - 2000 r / min.

19. The method for improving the development process according to claim 18, characterized in that, The spraying flow rate of the first nozzle is 1000 ml / min, and the rotation speed of the wafer is 1200 r / min.

20. The method for improving the development process according to claim 17, wherein In step S82, the rotation speed of the wafer is 2000 r / min, and the rotation time of the wafer is 25 s.

21. The method for improving the development process according to claim 1, wherein The thickness of the photoresist film formed on the surface of the wafer is 5 - 15 μm.

22. The method for improving the developing process according to claim 1, wherein, Between step S4 and step S5, the following steps are further included: S4a: Rotate the wafer along the first direction at the fifth rotation speed for the ninth preset time, and at the same time, use the second nozzle to spray the developer at a fixed point on the edge of the surface of the wafer at the fourth spraying rate. Between the step S6 and the step S7, the following steps are further included: S6a: Rotate the wafer along the second direction at a sixth rotation speed for a tenth preset time, and at the same time, use the second nozzle to spray the developer at a fixed point directly above the center of the wafer surface at a fifth spraying rate.

23. The method for improving the development process according to claim 22, wherein, The fourth spraying rate is 800 ml / min, the fifth rotation speed is 15 r / min, and the ninth preset time of the wafer is 4 s; the fifth spraying rate is 800 ml / min, the sixth rotation speed is 15 r / min, and the tenth preset time is 1 s.

24. The method for improving the development process according to claim 22, wherein, In the step S5, the second spraying rate is 800 ml / min, the speed of the second nozzle for reciprocating movement is 25 mm / s, the number of scans of the second nozzle is three times, the fifth rotation speed is 15 r / min, and the fifth preset time is 18 s.

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