Control Method and Control System for Key Dimensions

Abstract

The present invention provides a method and a control system for controlling critical dimensions. The control method includes: establishing a first database for the correspondence between the exposure dose of a photoresist and the variation value of critical dimensions; obtaining the actual variation value of critical dimensions, and obtaining the first correction amount of the exposure dose according to the actual variation value and the first database; establishing a second database for the correspondence between the waiting time between baking and developing of the photoresist and the variation value of critical dimensions; presetting a standard delay time between baking and developing, obtaining the actual waiting time between baking and developing of the photoresist, and determining the time difference between the actual waiting time and the standard delay time; obtaining the compensation variation value of critical dimensions according to the time difference and the second database; obtaining the second correction amount of the exposure dose according to the compensation variation value and the first database; correcting the exposure dose of the photoresist according to the first correction amount and the second correction amount; and adjusting the critical dimensions according to the corrected exposure dose.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more particularly, to a method and a control system for controlling critical dimensions. Background Art

[0002] In the process of semiconductor manufacturing, lithography is a commonly used manufacturing process, and various device patterns and line widths can be defined through lithography. The steps of lithography generally include: photoresist coating, soft baking (PAB, Post Adhesion Baking), alignment and exposure, post-exposure baking (PEB, Post exposure Baking), development, and hard baking (PDB, Post Develop baking). The quality of lithography has an important impact on the performance and yield of semiconductor devices.

[0003] With the continuous development of very large scale integrated circuits, the circuit design is becoming more and more complex and the feature size is getting smaller and smaller. The feature size of the circuit has an increasingly greater impact on the device performance. As an important medium for transferring the circuit pattern to the silicon wafer, the critical dimension (CD) of the photoresist pattern directly affects the actual pattern size on the silicon wafer, and ultimately affects the product yield. To ensure the accuracy of the actual critical dimension of the pattern on the silicon wafer, it is necessary to ensure the accuracy of the critical dimension of the photoresist pattern first.

[0004] The exposure dose (Dose) during lithography by the lithography machine directly affects the size of the critical dimension. The size of the critical dimension will affect the actual pattern size of subsequent processes such as pattern transfer, resulting in process instability and reducing the product yield. Therefore, it is necessary to accurately control the exposure dose according to the target critical dimension.

[0005] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present invention, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0006] The purpose of the embodiments of the present disclosure is to provide a method for controlling critical dimensions, which can improve the accuracy of the exposure dose for the next batch, and thereby improve the variation of the critical dimensions.

[0007] According to one aspect of the present disclosure, a method for controlling critical dimensions is provided. The method for controlling critical dimensions includes:

[0008] Establishing a first database of the correspondence between the exposure dose of the photoresist and the critical dimension variation value;

[0009] Obtaining the actual variation value of the critical dimension, and obtaining a first correction amount of the exposure dose according to the actual variation value and the first database;

[0010] Establish a second database for the correspondence between the waiting time between the baking and development of the photoresist and the critical dimension variation value;

[0011] Preset the standard delay time between the baking and development, obtain the actual waiting time between the baking and development of the photoresist, and determine the time difference between the actual waiting time and the standard delay time;

[0012] Obtain the compensated variation value of the critical dimension according to the time difference and the second database;

[0013] Obtain the second correction amount of the exposure dose according to the compensated variation value and the first database;

[0014] Correct the exposure dose of the photoresist according to the first correction amount and the second correction amount;

[0015] Adjust the critical dimension according to the corrected exposure dose.

[0016] In an exemplary embodiment of the present disclosure, establishing a first database for the correspondence between the exposure dose of the photoresist and the critical dimension variation value includes:

[0017] Provide a plurality of substrates, and form a photoresist on the substrates;

[0018] According to the target critical dimension value, preset the exposure dose to perform an exposure process on the photoresist;

[0019] Perform a baking process after the exposure process for a first time;

[0020] Perform a development process after the baking process for a second time;

[0021] Measure the measured critical dimension values of the photoresist under different exposure doses, and determine the critical dimension variation value according to the measured critical dimension values and the target critical dimension value;

[0022] Establish a first database for the correspondence between the exposure dose of the photoresist and the critical dimension variation value according to the variation value and the exposure dose.

[0023] In an exemplary embodiment of the present disclosure, establishing a first database for the correspondence between the exposure dose of the photoresist and the critical dimension variation value according to the variation value and the exposure dose includes:

[0024] According to the measured critical dimension values of the photoresist under multiple groups of different exposure doses, fit the first linear correlation coefficient between different exposure doses and the measured critical dimension values of the photoresist;

[0025] Establish a first database of the correspondence between the exposure dose of the photoresist and the critical dimension variation value according to the first linear correlation coefficient.

[0026] In an exemplary embodiment of the present disclosure, obtaining the actual variation value of the critical dimension, and obtaining the first correction amount of the exposure dose according to the actual variation value and the first database, includes:

[0027] Obtain the actual variation value of the critical dimension;

[0028] Obtain the first correction amount of the exposure dose according to the actual variation value and the first linear correlation coefficient.

[0029] In an exemplary embodiment of the present disclosure, establishing a second database of the correspondence between the waiting time between baking and developing of the photoresist and the critical dimension variation value, includes:

[0030] Preset the standard delay time and the maximum delay time between baking and developing;

[0031] Establish a second database of the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value.

[0032] In an exemplary embodiment of the present disclosure, establishing a second database of the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value, includes:

[0033] Provide a plurality of substrates, and form a photoresist on the substrates;

[0034] According to the target critical dimension value, preset the exposure dose to perform an exposure process on the photoresist;

[0035] Perform a baking process after a first time after the exposure process;

[0036] Perform a developing process after a second time after the baking process, and the second time is between the standard delay time and the maximum delay time;

[0037] Measure the measured critical dimension value of the photoresist at different second times, and determine the variation value of the critical dimension according to the measured critical dimension value and the target critical dimension value;

[0038] According to the variation value and the second time, establish a second database of the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value.

[0039] In an exemplary embodiment of the present disclosure, establishing a second database of the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value according to the variation value and the second time includes:

[0040] Fitting a second linear correlation coefficient between different second times and the measured critical dimension values of the photoresist according to the measured critical dimensions of the photoresist under multiple groups of different second times;

[0041] Establishing a second database of the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value according to the second linear correlation coefficient.

[0042] In an exemplary embodiment of the present disclosure, obtaining a compensation variation value of the critical dimension according to the time difference and the second database includes:

[0043] Obtaining the time difference and the second linear correlation coefficient;

[0044] Obtaining a compensation variation value of the critical dimension according to the time difference and the second linear correlation coefficient.

[0045] In an exemplary embodiment of the present disclosure, correcting the exposure dose of the photoresist according to the first correction amount and the second correction amount includes:

[0046] Obtaining the current exposure dose;

[0047] Subtracting the first correction amount from the current exposure dose and adding the second correction amount to obtain the corrected exposure dose.

[0048] In an exemplary embodiment of the present disclosure, the photoresist is a positive photoresist, and the critical dimension is the critical dimension of the etched part of the photoresist; or,

[0049] The photoresist is a negative photoresist, and the critical dimension is the critical dimension of the remaining part of the photoresist.

[0050] According to another aspect of the present disclosure, a control system for critical dimensions is provided. The control system for critical dimensions includes:

[0051] A first database, including the correspondence between the exposure dose of the photoresist and the critical dimension variation value, and simultaneously obtaining the actual variation value of the critical dimension;

[0052] A first correction unit, connected to the first database, and the first correction unit is configured to obtain a first correction amount of the exposure dose according to the actual variation value and the first database;

[0053] A second database, including a second database of the correspondence between the waiting time between the baking and developing of the photoresist and the critical dimension variation value;

[0054] A time difference unit, which presets a standard delay time between the baking and developing, and can simultaneously obtain the actual waiting time between the baking and developing of the photoresist, and determine the time difference between the actual waiting time and the standard delay time;

[0055] A compensation unit, connected to the second database and the time difference unit, and the compensation unit is configured to obtain a compensation variation value of the critical dimension according to the time difference and the second database;

[0056] A second correction unit, connected to the compensation unit and the first database, and the second correction unit is configured to obtain a second correction amount of the exposure dose according to the compensation variation value and the first database;

[0057] A third correction unit, connected to the first correction unit and the second correction unit, and the third correction unit is configured to correct the exposure dose of the photoresist according to the first correction amount and the second correction amount;

[0058] An adjustment unit, connected to the third correction unit, and the correction unit is configured to adjust the critical dimension according to the corrected exposure dose.

[0059] In an exemplary embodiment of the present disclosure, the first database includes a first linear correlation coefficient of different exposure doses and the measured critical dimension values of the photoresist obtained by fitting; the first correction unit is configured to obtain a first correction amount of the exposure dose according to the actual variation value and the first linear correlation coefficient.

[0060] In an exemplary embodiment of the present disclosure, the second database includes a second linear correlation coefficient of different actual delay times between the baking process and the developing process and the measured critical dimension values of the photoresist obtained by fitting; the second correction unit is configured to obtain a compensation variation value of the critical dimension according to the time difference and the second linear correlation coefficient.

[0061] In an exemplary embodiment of the present disclosure, the third correction unit is configured to obtain the current exposure dose, subtract the first correction amount from the current exposure dose, and add the second correction amount to obtain the corrected exposure dose.

[0062] In an exemplary embodiment of the present disclosure, the photoresist is a positive photoresist, and the critical dimension is the critical dimension of the etched part of the photoresist; or,

[0063] The photoresist is a negative photoresist, and the critical dimension is the critical dimension of the remaining part of the photoresist.

[0064] The method for controlling the critical dimension provided by the present disclosure establishes a first database of the correspondence between the exposure dose of the photoresist and the critical dimension variation value, and establishes a second database of the correspondence between the waiting time between baking and developing of the photoresist and the critical dimension variation value; by obtaining the actual variation value of the critical dimension, according to the actual variation value and the first database, the first correction amount of the exposure dose can be obtained; a standard delay time between baking and developing is preset, the actual waiting time between baking and developing of the photoresist is obtained, and the time difference between the actual waiting time and the standard delay time is determined. According to the time difference and the second database, the compensation variation value of the critical dimension can be obtained, and then according to the compensation variation value and the first database, the second correction amount of the exposure dose can be obtained; then according to the first correction amount and the second correction amount, the exposure dose of the Dose photoresist of the next lot is corrected, and then according to the corrected Dose, the adjustment of the critical dimension of the next lot is realized, avoiding the influence on the size of the critical dimension after development when the development delay time is too long, thereby avoiding the instability of the process and improving the product yield.

[0065] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present invention, and are used together with the specification to explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings according to these drawings without creative efforts. In the drawings:

[0067] Figure 1 is a flowchart of the method for controlling the critical dimension provided by an embodiment of the present disclosure;

[0068] Figure 2 is a schematic diagram of the correspondence between the exposure dose and the critical dimension in the R2R of the related art;

[0069] Figure 3 is a schematic diagram of the correspondence between the exposure dose and the critical dimension provided by an embodiment of the present disclosure;

[0070] Figure 4 is a schematic diagram of the correspondence between the waiting time and the critical dimension provided by an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0071] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art.

[0072] In addition, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of the present invention. However, those skilled in the art will recognize that the technical solutions of the present invention can be practiced without one or more of the specific details, or other methods, steps, etc. may be employed. In other instances, well-known methods, implementations, or operations are not shown or described in detail to avoid obscuring aspects of the present invention.

[0073] The flowcharts shown in the accompanying drawings are merely illustrative and not necessarily inclusive of all content and operations / steps, nor are they necessarily executed in the order described. For example, some operations / steps may be decomposed, while some operations / steps may be combined or partially combined, so the actual execution order may change according to the actual situation.

[0074] The inventors have found that the exposure dose (Dose) during lithography by a lithography machine directly affects the size of the critical dimension. In R2R (Run to Run, controlling subsequent production based on information obtained from previous operations), the relative relationship (Slope) between Dose and CD is used to calculate the Dose for the next lot based on the CD of the previous batch or several previous batches of wafers in the same lot. However, there is a development delay time between the post-exposure baking process and the development process of the photoresist.

[0075] Before the development process is carried out, there is a difference in the photoacid concentration between the exposed area and the unexposed area, and there is a photoacid diffusion phenomenon. According to Fick's second law, the concentration of photoacid at the junction between the unexposed area and the exposed area increases with time; as Figure 2 shown, when the development delay time is too long, it will affect the size of the critical dimension after development, abnormal CD leads to abnormal calculated DoseOPT, which in turn affects the Dose and CD of the next lot, affects the actual pattern size of subsequent processes such as pattern transfer, resulting in process instability and reducing the product yield.

[0076] In view of the above technical problems, the embodiments of the present disclosure provide a method for controlling critical dimensions, as Figure 1 shown, the method for controlling critical dimensions includes:

[0077] Step S100, establishing a first database of the correspondence between the exposure dose of the photoresist and the critical dimension variation value;

[0078] Step S200: Obtain the actual variation value of the critical dimension, and obtain the first correction amount of the exposure dose according to the actual variation value and the first database;

[0079] Step S300: Establish a second database for the correspondence between the waiting time between the baking and development of the photoresist and the critical dimension variation value;

[0080] Step S400: Preset the standard delay time between baking and development, obtain the actual waiting time between the baking and development of the photoresist, and determine the time difference between the actual waiting time and the standard delay time;

[0081] Step S500: Obtain the compensated variation value of the critical dimension according to the time difference and the second database;

[0082] Step S600: Obtain the second correction amount of the exposure dose according to the compensated variation value and the first database;

[0083] Step S700: Correct the exposure dose of the photoresist according to the first correction amount and the second correction amount;

[0084] Step S800: Adjust the critical dimension according to the corrected exposure dose.

[0085] The method for controlling the critical dimension provided by the present disclosure establishes a first database for the correspondence between the exposure dose of the photoresist and the critical dimension variation value, and establishes a second database for the correspondence between the waiting time between the baking and development of the photoresist and the critical dimension variation value; by obtaining the actual variation value of the critical dimension, according to the actual variation value and the first database, the first correction amount of the exposure dose can be obtained; preset the standard delay time between baking and development, obtain the actual waiting time between the baking and development of the photoresist, and determine the time difference between the actual waiting time and the standard delay time, according to the time difference and the second database, the compensated variation value of the critical dimension can be obtained, and then according to the compensated variation value and the first database, the second correction amount of the exposure dose can be obtained; then according to the first correction amount and the second correction amount, correct the exposure dose of the Dose photoresist for the next lot, and then according to the corrected Dose, realize the adjustment of the critical dimension of the next lot, avoiding the influence on the size of the critical dimension after development when the development delay time is too long, thereby avoiding process instability and improving product yield.

[0086] Next, each step in the method for controlling the critical dimension provided by the present disclosure will be described in detail.

[0087] In step S100, a first database for the correspondence between the exposure dose of the photoresist and the critical dimension variation value is established.

[0088] Specifically, a plurality of substrates are provided, and photoresist is formed on the substrates. According to the target critical dimension value, the photoresist is exposed with a preset exposure dose, and different exposure doses can be used to expose the photoresist on different substrates. The photoresist on each substrate is baked after a first period of time after the exposure process; the photoresist is developed after a second period of time after the baking process; then, the measured critical dimension values of the photoresist under different exposure doses are measured, and the variation value of the critical dimension is determined according to the difference between the measured critical dimension value and the target critical dimension value; according to the variation value and the exposure dose, a first database of the corresponding relationship between the exposure dose of the photoresist and the critical dimension variation value is established.

[0089] Wherein, when the photoresist is a positive photoresist, the critical dimension is the critical dimension of the etched part of the photoresist; when the photoresist is a negative photoresist, the critical dimension is the critical dimension of the remaining part of the photoresist.

[0090] Among them, as Figure 3 shown, according to the variation value and the exposure dose, a first database of the corresponding relationship between the exposure dose of the photoresist and the critical dimension variation value is established, including: according to the measured critical dimension values of the photoresist under multiple groups of different exposure doses, the first linear correlation coefficient (Slope) between different exposure doses and the measured critical dimension values of the photoresist is fitted; according to the first linear correlation coefficient, a first database of the corresponding relationship between the exposure dose of the photoresist and the critical dimension variation value is established.

[0091] In step S200, the actual variation value of the critical dimension is obtained, and according to the actual variation value and the first database, the first correction amount of the exposure dose is obtained.

[0092] Specifically, the actual variation value of the critical dimension is obtained; according to the actual variation value and the first linear correlation coefficient, the first correction amount of the exposure dose is obtained, and the first correction amount (Dose1) is:

[0093] Dose1 = (CD MET – CD target) / Slope

[0094] Wherein, CD MET is the measured critical dimension value, and CD target is the target critical dimension value.

[0095] In step S300, a second database of the corresponding relationship between the waiting time between baking and developing of the photoresist and the critical dimension variation value is established.

[0096] Specifically, the standard delay time and the maximum delay time between baking and developing are preset; a second database of the corresponding relationship between the time period between the standard delay time and the maximum delay time and the critical dimension variation value is established.

[0097] Among them, the standard delay time is the same waiting time between the baking and development of photoresist in each process. However, due to process and other reasons, the actual waiting time in each process is greater than the standard delay time. The maximum delay time is the longest delay time that can occur between the baking and development of photoresist in each process. If the actual waiting time exceeds the maximum delay time, the product yield may be significantly reduced.

[0098] Among them, the second database establishing the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value includes: providing a plurality of substrates, forming photoresist on the substrates; performing exposure treatment on the photoresist according to a preset exposure dose based on the target critical dimension value; performing baking treatment after the first time after the exposure treatment; performing development treatment after the second time after the baking treatment, where the second time is between the standard delay time and the maximum delay time; measuring the measured critical dimension value of the photoresist at different second times, and determining the critical dimension variation value according to the measured critical dimension value and the target critical dimension value; establishing the second database of the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value according to the variation value and the second time.

[0099] Among them, as Figure 4 shown, the second database establishing the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value according to the variation value and the second time includes: fitting the second linear correlation coefficient (Slope2) between different second times and the measured critical dimension value of the photoresist according to the measured critical dimension of the photoresist at multiple groups of different second times (PEB-Dev. Waiting time); establishing the second database of the correspondence between the time period between the standard delay time (Lag time) and the maximum delay time (Q-time) and the critical dimension variation value according to the second linear correlation coefficient.

[0100] Among them, different Slope_CD_Time are linearly simulated in different regions. When the second time is less than the standard delay time, the third linear correlation coefficient (Slope1) between different second times and the measured critical dimension value of the photoresist is fitted. The starting point of the gentle Slope region is set as the development lag time, and the end point is set as the Q-time. The Lag time can be, for example, 10 min - 70 min, and the Q-time can be, for example, 3 h - 18 h. By setting the lag time, the influence of PEB-Dev. Waiting time on CD or Dose OPT is reduced. This parameter is set in the R2R feedback system to participate in the calculation of the next batch of lot Dose delivery values, so as to improve the accuracy of the next batch of lot delivery values and further improve the CD variation.

[0101] In step S400, preset the standard delay time between baking and developing, obtain the actual waiting time between the photoresist baking and developing, and determine the time difference between the actual waiting time and the standard delay time.

[0102] Specifically, preset the standard delay time between baking and developing, obtain the actual waiting time between the photoresist baking and developing, and determine the time difference between the actual waiting time (Time Actual) and the standard delay time. The time difference (Time) is:

[0103] Time = Time Actual - Lag time

[0104] where Time Actual > Lag time.

[0105] In step S500, obtain the compensation variation value of the critical dimension according to the time difference and the second database.

[0106] Specifically, obtain the time difference and the second linear correlation coefficient; according to the time difference and the second linear correlation coefficient, obtain the compensation variation value of the critical dimension. The compensation variation value (CD1) is:

[0107] CD1 = Time × Slope2

[0108] In step S600, obtain the second correction amount of the exposure dose according to the compensation variation value and the first database.

[0109] Specifically, obtain the second correction amount of the exposure dose according to the compensation variation value and the first database. The second correction amount (Dose2) is:

[0110] Dose2 = CD1 / Slope

[0111] = Time × Slope2 / Slope

[0112] = (Time Actual - Lag time) × Slope2 / Slope

[0113] In step S700, correct the exposure dose of the photoresist according to the first correction amount and the second correction amount.

[0114] Specifically, obtain the current exposure dose (Dose used), subtract the first correction amount from the current exposure dose, and add the second correction amount to obtain the corrected exposure dose. The corrected exposure dose (Dose Opt) is:

[0115] Dose Opt = Dose use - Dose1 + Dose2

[0116] = Dose use-(CD MET–CD target) / Slope+(Time Actual -

[0117] Lag Time)×Slope2 / Slope

[0118] In step S800, the critical dimension is adjusted according to the corrected exposure dose.

[0119] Specifically, according to the corrected exposure dose (Dose Opt), the exposure dose for the next batch is set to achieve the adjustment of the critical dimension. Based on the original feedback of the relative relationship between CD and Dose, the present disclosure incorporates the influence of PEB - Dev.Time on the Dose OPT value, thereby improving the accuracy of OPT to improve CD variation, avoiding CD anomalies caused by Time Actual, and preventing CD anomalies from causing abnormal calculated Dose OPT, which in turn affects the Dose and CD of the next batch of lots.

[0120] An embodiment of the present disclosure also provides a control system for critical dimensions, which includes: a first database, a first correction unit, a second database, a time difference unit, a compensation unit, a second correction unit, a third correction unit, and an adjustment unit.

[0121] Among them, the first database includes the correspondence between the exposure dose of the photoresist and the critical dimension variation value, and simultaneously obtains the actual variation value of the critical dimension; the first correction unit is connected to the first database, and the first correction unit is configured to obtain the first correction amount of the exposure dose according to the actual variation value and the first database; the second database is a second database including the correspondence between the waiting time between baking and developing of the photoresist and the critical dimension variation value; the time difference unit presets the standard delay time between baking and developing, and can simultaneously obtain the actual waiting time between baking and developing of the photoresist, and determine the time difference between the actual waiting time and the standard delay time; the compensation unit is connected to the second database and the time difference unit, and the compensation unit is configured to obtain the compensated variation value of the critical dimension according to the time difference and the second database; the second correction unit is connected to the compensation unit and the first database, and the second correction unit is configured to obtain the second correction amount of the exposure dose according to the compensated variation value and the first database; the third correction unit is connected to the first correction unit and the second correction unit, and the third correction unit is configured to correct the exposure dose of the photoresist according to the first correction amount and the second correction amount; the adjustment unit is connected to the third correction unit, and the correction unit is configured to adjust the critical dimension according to the corrected exposure dose.

[0122] The control system for critical dimensions provided by the present disclosure includes a first database that provides a first database of the correspondence between the exposure dose of photoresist and the critical dimension variation value, and a second database that provides a second database of the correspondence between the waiting time between baking and developing of photoresist and the critical dimension variation value; the first correction unit can obtain the first correction amount of the exposure dose according to the actual variation value of the critical dimension and the first database; the time difference unit can obtain the actual waiting time between baking and developing of photoresist according to the preset standard delay time between baking and developing, and determine the time difference between the actual waiting time and the standard delay time; the compensation unit can obtain the compensation variation value of the critical dimension according to the time difference and the second database; the second correction unit can obtain the second correction amount of the exposure dose according to the compensation variation value and the first database; the third correction unit can correct the exposure dose of the Dose photoresist for the next batch of lots according to the first correction amount and the second correction amount; the adjustment unit can adjust the critical dimensions of the next batch according to the corrected Dose, avoiding the influence on the size of the critical dimensions after development when the developing delay time is too long, thereby avoiding process instability and improving the product yield.

[0123] Specifically, photoresist is formed on multiple substrates respectively; according to the target critical dimension value, a preset exposure dose is used to perform an exposure process on the photoresist, and different exposure doses can be used to perform the exposure process on the photoresist on different substrates; the photoresist on each substrate is baked after a first period of time after the exposure process; the photoresist is developed after a second period of time after the baking process; then, the measured critical dimension values of the photoresist under different exposure doses are measured, and the variation value of the critical dimension is determined according to the difference between the measured critical dimension value and the target critical dimension value; according to the variation value and the exposure dose, a first database of the correspondence between the exposure dose of the photoresist and the critical dimension variation value is established. Wherein, when the photoresist is a positive photoresist, the critical dimension is the critical dimension of the etched part of the photoresist; when the photoresist is a negative photoresist, the critical dimension is the critical dimension of the remaining part of the photoresist.

[0124] Among them, as Figure 3 shown, according to the measured critical dimension values of the photoresist under multiple groups of different exposure doses, a first linear correlation coefficient (Slope) between different exposure doses and the measured critical dimension values of the photoresist is fitted; according to the first linear correlation coefficient, a first database of the correspondence between the exposure dose of the photoresist and the critical dimension variation value is established.

[0125] Specifically, the first correction unit obtains the first correction amount of the exposure dose according to the actual variation value and the first linear correlation coefficient, and the first correction amount (Dose1) is:

[0126] Dose1 = (CD MET – CD target) / Slope

[0127] Among them, CD MET is the measured critical dimension value, and CD target is the target critical dimension value.

[0128] Specifically, the time difference unit presets a standard delay time and a maximum delay time between preset baking and development; a second database establishing a correspondence relationship between a time period between the standard delay time and the maximum delay time and a critical dimension variation value is established. Among them, the standard delay time is the same waiting time between baking and development of the photoresist in each process, but due to process and other reasons, the actual waiting time in each process is greater than the standard delay time. The maximum delay time is the longest delay time that can be allowed between baking and development of the photoresist in each process. If the actual waiting time exceeds the maximum delay time, the product yield can be greatly reduced.

[0129] Among them, the second database establishing a correspondence relationship between a time period between the standard delay time and the maximum delay time and a critical dimension variation value includes: forming a photoresist on multiple substrates respectively; performing an exposure process on the photoresist according to the target critical dimension value by presetting an exposure dose; performing a baking process after a first time after the exposure process; performing a development process after a second time after the baking process, and the second time is between the standard delay time and the maximum delay time; measuring the measured critical dimension value of the photoresist at different second times (different actual delay times between the baking process and the development process), and determining the variation value of the critical dimension according to the measured critical dimension value and the target critical dimension value; fitting a second linear correlation coefficient (Slope2) between different second times and the measured critical dimension value of the photoresist according to the measured critical dimension values of the photoresist at multiple groups of different second times (PEB-Dev. Waiting time); establishing a second database establishing a correspondence relationship between a time period between the standard delay time (Lagtime) and the maximum delay time (Q-time) and a critical dimension variation value according to the second linear correlation coefficient.

[0130] Among them, different Slope_CD_Time are linearly simulated in different regions. When the second time is less than the standard delay time, a third linear correlation coefficient (Slope1) between different second times and the measured critical dimension value of the photoresist is fitted. The starting point of the gentle Slope region is set as the development lag time, and the end point is set as Q-time. The Lag time can be, for example, 10 min - 70 min, and the Q-time can be, for example, 3 h - 18 h. By setting the lag time, the influence of PEB-Dev. Waiting time on CD or Dose OPT is reduced. This parameter is set in the R2R feedback system to participate in the calculation of the next batch of lot Dose shipment values, so as to improve the accuracy of the next batch of lot shipment values, and further improve CD variation.

[0131] Specifically, the time difference unit presets a standard delay time between baking and developing, obtains the actual waiting time between photoresist baking and developing, and determines the time difference between the actual waiting time (Time Actual) and the standard delay time. The time difference (Time) is:

[0132] Time = Time Actual - Lag time

[0133] Where Time Actual > Lag time.

[0134] Specifically, the compensation unit obtains the time difference and the second linear correlation coefficient; according to the time difference and the second linear correlation coefficient, obtains the compensation variation value of the critical dimension. The compensation variation value (CD1) is:

[0135] CD1 = Time × Slope2

[0136] Specifically, the second correction unit obtains the second correction amount of the exposure dose according to the compensation variation value and the first database. The second correction amount (Dose2) is:

[0137] Dose2 = CD1 / Slope

[0138] = Time × Slope2 / Slope

[0139] = (Time Actual - Lag time) × Slope2 / Slope

[0140] Specifically, the third correction unit obtains the current exposure dose (Dose used), subtracts the first correction amount from the current exposure dose, and adds the second correction amount to obtain the corrected exposure dose. The corrected exposure dose (Dose Opt) is:

[0141] Dose Opt = Dose use - Dose1 + Dose2

[0142] = Dose use - (CD MET – CD target) / Slope + (Time Actual -

[0143] Lag Time) × Slope2 / Slope

[0144] Specifically, the adjustment unit sets the exposure dose for the next batch according to the corrected exposure dose (Dose Opt) to achieve the adjustment of the critical dimension. Based on the original feedback of the relative relationship between CD and Dose, the present disclosure incorporates the influence of PEB-Dev.Time on the Dose OPT value, thereby improving the accuracy of OPT to reduce CD variation, avoiding CD abnormalities caused by TimeActual, and preventing CD abnormalities from causing abnormal Dose OPT calculations, which in turn affect the Dose and CD of the next batch of lots. Those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include known common knowledge or conventional technical means in the technical field not disclosed in the present invention. The specification and examples are only considered exemplary, and the true scope and spirit of the present invention are pointed out by the following claims.

[0145] It should be understood that the present invention is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A method for controlling critical dimensions, characterized in that, it includes: establishing a first database for the correspondence between the exposure dose of photoresist and the critical dimension variation value; obtaining the actual variation value of the critical dimension, and obtaining the first correction amount of the exposure dose according to the actual variation value and the first database; establishing a second database for the correspondence between the waiting time between baking and developing of photoresist and the critical dimension variation value; presetting the standard delay time between baking and developing, obtaining the actual waiting time between baking and developing of photoresist, and determining the time difference between the actual waiting time and the standard delay time; obtaining the compensated variation value of the critical dimension according to the time difference and the second database; obtaining the second correction amount of the exposure dose according to the compensated variation value and the first database; correcting the exposure dose of photoresist according to the first correction amount and the second correction amount; adjusting the critical dimension according to the corrected exposure dose.

2. The control method according to claim 1, characterized in that, establishing a first database for the correspondence between the exposure dose of photoresist and the critical dimension variation value includes: providing a plurality of substrates, and forming photoresist on the substrates; presetting the exposure dose according to the target critical dimension value and performing exposure treatment on the photoresist; performing baking treatment after a first time after the exposure treatment; performing developing treatment after a second time after the baking treatment; measuring the measured critical dimension value of the photoresist under different exposure doses, and determining the variation value of the critical dimension according to the measured critical dimension value and the target critical dimension value; establishing a first database for the correspondence between the exposure dose of photoresist and the critical dimension variation value according to the variation value and the exposure dose.

3. The control method according to claim 2, characterized in that, establishing a first database for the correspondence between the exposure dose of photoresist and the critical dimension variation value according to the variation value and the exposure dose includes: fitting a first linear correlation coefficient between different exposure doses and the measured critical dimension value of the photoresist according to the measured critical dimension values of the photoresist under multiple groups of different exposure doses; establishing a first database for the correspondence between the exposure dose of photoresist and the critical dimension variation value according to the first linear correlation coefficient.

4. The control method according to claim 3, characterized in that, obtaining the actual variation value of the critical dimension, and obtaining the first correction amount of the exposure dose according to the actual variation value and the first database includes: obtaining the actual variation value of the critical dimension; obtaining the first correction amount of the exposure dose according to the actual variation value and the first linear correlation coefficient.

5. The control method according to claim 1, characterized in that, establishing a second database for the correspondence between the waiting time between baking and developing of photoresist and the critical dimension variation value includes: presetting the standard delay time and the maximum delay time between baking and developing; establishing a second database for the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value.

6. The control method according to claim 5, characterized in that, A second database for establishing the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value, comprising: Providing a plurality of substrates, and forming a photoresist on the substrates; Performing an exposure process on the photoresist according to a preset exposure dose based on a target critical dimension value; Performing a baking process after a first time after the exposure process; Performing a developing process after a second time after the baking process, the second time being between the standard delay time and the maximum delay time; Measuring the measured critical dimension value of the photoresist at different second times, and determining the variation value of the critical dimension according to the measured critical dimension value and the target critical dimension value; Establishing a second database for the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value according to the variation value and the second time.

7. The control method according to claim 6, wherein, Establishing a second database for the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value according to the variation value and the second time, comprising: Fitting a second linear correlation coefficient between different second times and the measured critical dimension value of the photoresist according to the measured critical dimensions of the photoresist at multiple groups of different second times; Establishing a second database for the correspondence between the time period between the standard delay time and the maximum delay time and the critical dimension variation value according to the second linear correlation coefficient.

8. The control method according to claim 7, wherein, Obtaining the compensated variation value of the critical dimension according to the time difference and the second database, comprising: Obtaining the time difference and the second linear correlation coefficient; Obtaining the compensated variation value of the critical dimension according to the time difference and the second linear correlation coefficient.

9. The control method according to claim 1, wherein, Correcting the exposure dose of the photoresist according to the first correction amount and the second correction amount, comprising: Obtaining the current exposure dose; Subtracting the first correction amount from the current exposure dose and adding the second correction amount to obtain the corrected exposure dose.

10. The control method according to claim 1, wherein, The photoresist is a positive photoresist, and the critical dimension is the critical dimension of the etched part of the photoresist; or, The photoresist is a negative photoresist, and the critical dimension is the critical dimension of the remaining part of the photoresist.

11. A control system for critical dimensions, wherein, Comprising: A first database, including the correspondence between the exposure dose of the photoresist and the critical dimension variation value, and simultaneously obtaining the actual variation value of the critical dimension; A first correction unit, connected to the first database, the first correction unit being configured to obtain a first correction amount of the exposure dose according to the actual variation value and the first database; A second database, including a second database of the correspondence between the waiting time between the baking and developing of the photoresist and the critical dimension variation value; A time difference unit that preset a standard delay time between baking and developing, and can simultaneously obtain the actual waiting time between photoresist baking and developing, and determine the time difference between the actual waiting time and the standard delay time; A compensation unit connected to the second database and the time difference unit, the compensation unit is configured to obtain a compensation variation value of the critical dimension according to the time difference and the second database; A second correction unit connected to the compensation unit and the first database, the second correction unit is configured to obtain a second correction amount of the exposure dose according to the compensation variation value and the first database; A third correction unit connected to the first correction unit and the second correction unit, the third correction unit is configured to correct the exposure dose of the photoresist according to the first correction amount and the second correction amount; An adjustment unit connected to the third correction unit, the correction unit is configured to adjust the critical dimension according to the corrected exposure dose.

12. The control system according to claim 11, wherein, The first database includes a first linear correlation coefficient obtained by fitting different exposure doses and measured critical dimension values of the photoresist; the first correction unit is configured to obtain a first correction amount of the exposure dose according to the actual variation value and the first linear correlation coefficient.

13. The control system according to claim 11, wherein, The second database includes a second linear correlation coefficient obtained by fitting different actual delay times between baking process and developing process and measured critical dimension values of the photoresist; The second correction unit is configured to obtain a compensation variation value of the critical dimension according to the time difference and the second linear correlation coefficient.

14. The control system according to claim 11, wherein, The third correction unit is configured to obtain the current exposure dose, subtract the first correction amount from the current exposure dose, and add the second correction amount to obtain the corrected exposure dose.

15. The control system according to claim 11, wherein, The photoresist is a positive photoresist, and the critical dimension is the critical dimension of the etched part of the photoresist; or, The photoresist is a negative photoresist, and the critical dimension is the critical dimension of the remaining part of the photoresist.

Images