CN-122018247-A - Method for solving abnormal photoetching morphology

CN122018247ACN 122018247 ACN122018247 ACN 122018247ACN-122018247-A

Abstract

A method for solving the problem of abnormal photoetching morphology comprises the steps of S1 gluing, exposing and developing a product sheet on a production line, S2 observing morphology and abnormal photoetching morphology, S3 providing a first offline test sheet, S4 gluing, exposing and developing, S5 sending the first offline test sheet into an exposing machine of the step S4 again, wherein the average value of the optimal focus is larger than the fixed step range of the step S4, S6 taking the average value of the optimal focus of the step S5 as a complement value to the exposing machine of the step S4, S7 providing a second offline test sheet, S8 gluing, exposing and developing, wherein the exposing machine has the complement value, S9 sending the second offline test sheet into the exposing machine of the step S8 again, wherein the average value of the optimal focus is smaller than or equal to the fixed step range of the step S4, S10 taking the complement value of a normal imaging focal length as the complement value of the exposing machine of the product sheet on the line, gluing, exposing and developing the product sheet on the production line, S11 observing morphology and recovering the morphology.

Inventors

WANG YUE
SUN SHANSHAN
ZHOU HONGYU
LI HAITAO

Assignees

安徽晶微科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260313

Claims (10)

1. A method of resolving a lithographic topography anomaly, comprising the steps of: S1, gluing, exposing and developing a product sheet on a production line, wherein during exposure, crystal grains distributed in a two-dimensional array along an X direction and a Y direction form a photomask of the product sheet, and FEM data is adopted for exposure, in FEM data, exposure dose is constant, an imaging focal length is changed along the X direction or the Y direction by taking the crystal grain at the center of the product sheet as a normal imaging focal length F and along with the crystal grain, a fixed step length delta F is changed, the imaging focal length is increased from left to right when the imaging focal length is changed in the X direction, and the imaging focal length is increased from top to bottom when the imaging focal length is changed in the Y direction; S2, observing the appearance of a product sheet on a production line, if the observed line white edge is larger than a specified value, indicating that the photoetching appearance is abnormal, and executing a subsequent step S3, otherwise, ensuring that the photoetching appearance is normal, and the process parameters of gluing, exposure and development of the step S1 are used for subsequent production, so that the steps after the step S2 are not required to be executed; s3, providing a product piece before photoetching as a first in-line test piece under the condition that the photoetching morphology is judged to be abnormal in the step S2; S4, gluing, exposing and developing the first in-line test piece, wherein the photoetching parameters of products on the same production line are the same except that the exposed mask is a mask with the best testing focus different from the mask of the in-line product piece, the normal imaging focal length F ́ of the exposure is zero, and the fixed step length delta F ́ is not more than the fixed step length delta F on the production line of the step S1; S5, sending the developed first under-line test piece into the exposure machine table in the step S4 again to perform an optimal focus test and obtain an average value of the optimal focus, if the average value of the optimal focus is smaller than or equal to the range of the fixed step length of the + -DeltaF ́ in the step S4, indicating that the abnormal morphology of the on-line product is not caused by the fluctuation of the normal imaging focal length of the exposure machine table of the on-line product, and the problem of the abnormal morphology of the on-line product needs to be solved from other aspects of the photoetching process, and steps after the step S5 are not needed to be executed, and if the average value of the optimal focus is larger than the range of the fixed step length of the + -DeltaF ́ in the step S4, performing the step S6; s6, taking the average value of the best focus in the step S5 as a complement value to be added to the exposed machine in the step S4, so that the actual normal imaging focal length of the machine after the complement value is the sum of the normal imaging focal length F ́ in the step S4 and the complement value; S7, providing another product piece before photoetching as a second offline test piece; s8, gluing, exposing and developing the second offline test piece, wherein the exposed machine is based on the actual normal imaging focal length of the machine after the step S6 is carried out on the complement value of the normal imaging focal length and the crystal grain at the center of the second offline test piece is the complement value; S9, sending the developed second offline test piece into the exposure machine of the step S8 again to perform an optimal focus test and obtain an average value of the optimal focus, if the average value of the optimal focus is smaller than or equal to the range of the + -DeltaF ́ fixed step length of the step S4, taking the complement value of the normal imaging focal length as the complement value of the exposure machine of the online product piece, and performing the step S10, if the average value of the optimal focus is larger than the range of the + -DeltaF ́ fixed step length of the step S4, the complement value of the normal imaging focal length cannot be taken as the complement value of the exposure machine of the online product piece, and the problem needs to be solved from other aspects of the photoetching process, and the steps after the step S10 are not executed; S10, gluing, exposing and developing a product sheet on a production line, wherein the exposed machine is based on the actual normal imaging focal length of the machine after the complement value of the normal imaging focal length is obtained in the step S9 and the crystal grain at the center of the product sheet is the complement value; S11, observing the appearance of a product sheet on the production line, if the observed line white edge is smaller than a specified value, the photoetching appearance is restored to be normal, the process parameters of gluing, exposure and development in the step S10 are used for subsequent production on the production line, and if the observed line white edge is still larger than the specified value, the solving method of the photoetching appearance abnormality fails and needs to be solved from other aspects of the photoetching process.
2. The method of claim 1, wherein the step of resolving the lithographic topography anomalies, In step S1, step S3, step S7 and step S10, The product piece is a wafer with the diameter of 8 inches and the surface being plated with a 150A thick SIN film layer.
3. The method of claim 1, wherein the step of resolving the lithographic topography anomalies, In step S1, step S4, step S8 and step S10, The gluing comprises the following substeps: sa, forming an HMDS film, and forming the HMDS film on the surface of the product sheet in a gas phase mode; Sb, cooling before spin coating, and cooling the product sheet with the HMDS film formed on the surface to the temperature required by spin coating in a cooling tank; Sc, coating, namely spin coating the product sheet with spin coating glue in a glue coating process groove; And Sd, pre-baking, namely pre-baking the product sheet subjected to spin coating and glue homogenizing in a pre-baking process tank.
4. A method of resolving a lithographic topography anomaly as claimed in claim 3, In the sub-step Sa, Placing a product sheet on a carrying platform of a vacuum chamber, heating the carrying platform to 110 ℃, taking nitrogen as carrier gas, wherein the pressure of the nitrogen is 25kPa, introducing HMDS steam carried by the nitrogen, keeping the pressure of the vacuum chamber at 20Pa, introducing the HMDS steam carried by the nitrogen for 60s, and forming an HMDS film with the thickness of 6A; In sub-step Sb, the temperature required for spin coating is 23 ℃.
5. A method of resolving a lithographic topography anomaly as claimed in claim 3, In the substep Sc, the spin coating and gluing process comprises the steps of dripping 1.5mL of glue solution to the center position of a 2500rmp dynamic product sheet, rotating the product sheet for 35s at 2400rpm after the glue solution is dripped for 2s, and finally, gluing the product sheet to a thickness of 4800A; in substep Sc, the glue model is DHK-BF511; In sub-step Sd, the pre-bake temperature is 110 ℃ for 60s.
6. The method of claim 1, wherein the step of resolving the lithographic topography anomalies, In step S5 and step S9, In the best focus test, two separate curves in the X and Y directions are generated, and the curves in the X and Y directions are defined in such a way that the curves in different directions reach the best imaging quality at different Z-axis positions due to inherent astigmatism of the lens of the exposure machine, the 'best focus' to be aligned by exposure is a plane, and the average value of the 'best focus' of the two separate curves in the X and Y directions is taken as the 'best focus' to be aligned by exposure.
7. The method of claim 6, wherein the step of removing the lithographic anomalies, In step S6 and step S10, The normal imaging focal length and the complement of the normal imaging focal length are performed by an offset and offset calibration (AIS) input field in the wafer focus (Wafer Focusing) in an ADJUST station parameter window (ADJUST MACHINE PARAMETERS) in the control interface of the exposure station.
8. A method of resolving a lithographic topography anomaly as claimed in claim 3, In step S1, step S4, step S8 and step S10, The exposure includes the sub-steps of: si, cooling before exposure, and cooling the glued pre-baked product sheet in a cooling tank to the temperature of 23 ℃ required by exposure; Sii, exposing, namely performing step-and-scan exposure by using a photomask and a Nikon S205C machine, wherein the step X direction is 12949 mu m, the step Y direction is 250389 mu m, the exposure dose of each step-and-scan exposure is 20mj/cm 2 , and the NA value is 0.68; Siii, performing post-exposure baking in a post-exposure baking process tank, wherein the temperature of the post-exposure baking is 110 ℃ and the time is 120; Wherein, the The photomask of the step S1 and the step S10 is VOT612-010-BE, F is zero, and DeltaF is 0.05 mu m; the reticles of step S4 and step S8 were Nikon R2504HMF, ΔF ́ of 0.05 μm.
9. The method of resolving a lithographic topography anomaly of claim 8, In step S1, step S4, step S8 and step S10, The development includes the sub-steps of: SI, cooling before development, cooling the post-exposure baked product pieces in a cooling tank to a temperature of 23 ℃ required for development; SII, developing, namely placing a product sheet cooled before developing on a rotary table of a developing machine, dripping developing solution to the center of the product sheet while rotating, and flushing while rotating, wherein the rotation is unidirectional rotation, the rotating speed is 2000rpm, positive photoresist developing solution is adopted, the model of the developing solution is ZX-238 type, the developing time is 60s, and the flushing time is 30s; SIII, post-baking in a post-baking process tank, wherein the post-baking temperature is 110 ℃ and the post-baking time is 90s.
10. The method of claim 1, wherein the step of resolving the lithographic topography anomalies, In step S2 and step S11, the observation morphology is performed under a line width scanning electron microscope.

Description

Method for solving abnormal photoetching morphology Technical Field The present disclosure relates to the field of semiconductors, and more particularly to a method of resolving lithographic topographical anomalies. Background In semiconductor manufacturing, photolithography is one of the key technologies for integrated circuits. Photolithography generally involves gumming, exposure and development. After development is completed, the photoetching result, particularly the photoetching morphology, which refers to the three-dimensional contour feature of the graph formed by photoetching, is usually observed under a scanning electron microscope, the line white edge of the three-dimensional contour is one of the morphology features, the line white edge represents the verticality of the side wall or the flatness of the side wall of the line in the vertical direction, and the reduction of the line white edge is the key for improving the three-dimensional contour precision and yield of the photoetching graph. In production, the large line white edge is considered as abnormal photoetching morphology, and is derived from several main aspects of environment, equipment, materials, process parameters and the like, so that further intensive research is needed to provide a solution for production. Disclosure of Invention In view of the problems in the background art, an object of the present disclosure is to provide a method for solving a lithography morphology anomaly, which can provide a solution for the lithography morphology anomaly with a large line white edge. It is another object of the present disclosure to provide a method of resolving lithographic anomalies that can resolve lithographic anomalies more efficiently and at lower cost. The method for solving the problem of abnormal photoetching morphology comprises the following steps of S1, gluing product sheets on a production line, Exposing and developing, wherein during exposing, crystal grains distributed in two-dimensional arrays along X direction and Y direction are adopted to form a photomask of a product sheet, FEM data are adopted to expose, in FEM data, exposure dose is constant, imaging focal length is changed along X direction or Y direction by taking crystal grains positioned at the center of the product sheet as normal imaging focal length F and carrying out fixed step length delta F along with the crystal grains, imaging focal length is increased from left to right when the imaging focal length is changed along X direction, imaging focal length is increased from top to bottom when the imaging focal length is changed along Y direction, S2, observing the appearance of the product sheet on a production line, if the observed line white edge is larger than a specified value, indicating that the photoetching appearance is abnormal, and executing a subsequent step S3, otherwise, photoetching appearance is normal and gluing in step S1, The exposure and development process parameters are used for subsequent production without executing the steps after the step S2, S3, in the case that the photoetching appearance is judged to be abnormal in the step S2, a piece of product sheet before photoetching is provided as a first in-line test sheet, S4, the first in-line test sheet is glued, exposed and developed, wherein the mask except the exposure is a mask with the best focus for testing different from the mask of the in-line product sheet, and the normal imaging focal length F ́ of the exposure is zero, The fixed step length DeltaF ́ is not larger than the fixed step length DeltaF of the production line of the step S1, the photoetching parameters of the other production line products are the same, S5, the developed first under-line test piece is sent to the exposure machine of the step S4 again for carrying out the best focus test and obtaining the average value of the best focus, if the average value of the best focus is smaller than or equal to the range of the fixed step length of the + -DeltaF ́ of the step S4, the abnormality of the appearance of the on-line products is not caused by the fluctuation of the normal imaging focal length of the exposure machine of the on-line products, the problem needs to be solved from other aspects of the photoetching process, the step S5 is not needed to be executed, if the average value of the best focus is larger than the range of the fixed step length of the + -DeltaF ́ of the step S4, the step S6 is carried out, S6, the average value of the best focus of the step S5 is taken as the complement value to the exposure machine of the step S4, the actual normal imaging focal length F ́ of the complement value of the machine of the step S4 is the sum of the complement value, S7, the other before the other production line is provided, the second under-line test piece is tested, and the photoetching process is carried out on the second under-line test piece, Exposing and developing, wherein the exposed machine is based on