Advanced process control method for dynamically correcting optimal exposure energy of photoetching process
By collecting and feedbacking the basic data of the mask plate in the APC system, the optimal exposure energy of the lithography process is dynamically corrected, and the problem of the impact of the key size and light transmittance of the mask plate pattern on the lithography energy is solved, which improves the photolithography accuracy and efficiency and reduces costs.
Patent Information
- Application Number
- CN202510296352.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-12
- Publication Date
- 2025-05-30
AI Technical Summary
The existing APC system does not consider the impact of the key size of the mask plate and the transmittance on the optimal exposure energy of the lithography process, resulting in a decrease in the intercalation accuracy and increasing the lithography cost.
By collecting the basic data of the replacing mask plate corresponding to the lithography machine and the film layer to be lithographically, including the ideal key size, light transmittance and mask error enhancement factors of the mask plate pattern, it is fed back to the advanced process control system to dynamically correct the optimal exposure energy.
Effectively compensate for the optimal exposure energy corresponding to the old mask version, improve the intercalation accuracy of the lithography process, reduce lithography costs, and improve lithography efficiency.
Smart Images
Figure CN120065642A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of lithography advanced process control (APC), and particularly to an advanced process control method for dynamically correcting the optimal exposure energy of a lithography process. Background Art
[0002] An APC (Advanced Process Control) system collects the actual lithography process parameters of each lot, as well as the corresponding Overlay (the alignment accuracy between the current layer pattern and the previous layer pattern when forming the current layer pattern) and the critical dimension (CD) measurement results of the pattern. Based on the actual lithography process parameters of each lot, as well as the corresponding Overlay and the critical dimension of the pattern, a new recommended optimized process parameter is calculated through the Feedback model formula in the Feedback module of the APC system, and is automatically provided to the lithography process of the next batch of products to be lithographed. This process is repeated cyclically to achieve the automatic control and optimization of the lithography process parameters.
[0003] Currently, the APC system sets the optimal exposure energy for shipping based on the photoresist, machine, platform, and the film layer to be lithographed. However, in the actual lithography process, the mask (reticle) also affects the optimal exposure energy for shipping the wafer. When using the newly replaced mask for the first run (shipping), the default is to use the optimal exposure energy preset by the platform or the optimal exposure energy corresponding to the old mask. However, if there are differences in the critical dimensions (CD) of the mask patterns on the new mask and the old mask, the optimal exposure energy often also varies; in addition, the clear ratio of the mask also affects the optimal exposure energy for shipping.
[0004] Currently, the APC system does not consider the influence of mask CD & clear ratio on the optimal exposure energy for shipping, which affects the overlay accuracy. Therefore, it is often necessary to adjust the optimal exposure energy for shipping after rework, which is time-consuming and laborious, and also greatly increases the manufacturing cost. Summary of the Invention
[0005] This application provides an advanced process control method for dynamically correcting the optimal exposure energy of a lithography process, which can solve the problem that the current APC system does not consider the influence of mask CD & clear ratio on the optimal exposure energy for shipping, resulting in an impact on the overlay accuracy and thus increasing the lithography cost.
[0006] An embodiment of this application provides an advanced process control method for dynamically correcting the optimal exposure energy of a lithography process, including:
[0007] Collect the basic data of the lithography process according to the reticle corresponding to the lithography machine stage and the film layer to be lithographed. The basic lithography data at least includes: the ideal critical dimension of the reticle pattern, the reticle transmittance, and the mask error enhancement factor;
[0008] Feed back the basic lithography data to the advanced process control system;
[0009] Use the process control system to obtain the current optimal exposure energy, and feed back the current optimal exposure energy to the lithography machine stage;
[0010] Perform lithography on the film layer to be lithographed according to the current optimal exposure energy.
[0011] Optionally, in the advanced process control method for dynamically correcting the optimal exposure energy of the lithography process, the step of using the process control system to obtain the current optimal exposure energy and feeding back the current optimal exposure energy to the lithography machine stage includes:
[0012] Confirm whether the current batch is the first pass using the reticle of the reticle change;
[0013] If the current batch is the first pass using the reticle of the reticle change, obtain the critical dimension deviation of the wafer pattern through the first calculation formula; if the current batch is not the first pass using the reticle of the reticle change, obtain the critical dimension deviation of the wafer pattern through the second calculation formula;
[0014] Obtain the current optimal exposure energy according to the ideal optimal exposure energy, the reticle transmittance, and the critical dimension deviation;
[0015] Feed back the current optimal exposure energy to the lithography machine stage to dynamically correct the optimal exposure energy.
[0016] Optionally, in the advanced process control method for dynamically correcting the optimal exposure energy of the lithography process, the first calculation formula is: CD wafer diff =(CD mask target -CD mask coa )*MEEF / 4, where CD wafer diff is the critical dimension deviation of the wafer pattern; CD mask target is the ideal critical dimension of the reticle pattern; CD mask coa is the actually measured critical dimension of the reticle pattern; MEEF is the mask error enhancement factor.
[0017] Optionally, in the advanced process control method for dynamically correcting the optimal exposure energy of the lithography process, the second calculation formula is: CD wafer diff = CD wafer target - CD wafer measure , where CD wafer diff is the critical dimension deviation of the wafer pattern; CD wafer target is the ideal critical dimension of the wafer pattern; CD wafer measure is the actual critical dimension of the wafer pattern actually measured during the previous batch transfer.
[0018] Optionally, in the advanced process control method for dynamically correcting the optimal exposure energy of the lithography process, the calculation formula for obtaining the actual optimal exposure energy based on the ideal optimal exposure energy, the mask transparency, and the critical dimension deviation is:
[0019] E new = E old +(CD wafer diff / Slope)*(1 + R);
[0020] where E new is the actual optimal exposure energy corresponding to the mask of the version change; E old is the optimal exposure energy corresponding to the mask of the old version; CD wafer diff is the critical dimension deviation of the wafer pattern; Slope is a constant related to the lithography process; R is the contribution value of the mask transparency to the optimal exposure energy.
[0021] Optionally, in the advanced process control method for dynamically correcting the optimal exposure energy of the lithography process, the mask pattern is a trench pattern, a line pattern, and a hole pattern.
[0022] Optionally, in the advanced process control method for dynamically correcting the optimal exposure energy of the lithography process, the value range of MEEF is 2 to 3.
[0023] The technical solution of the present application has at least the following advantages:
[0024] In the advanced process control method for dynamically correcting the optimal exposure energy of the lithography process provided by this application, by feeding back the basic data of the lithography process collected to the advanced process control system, compensating for the optimal exposure energy corresponding to the old version of the mask according to all the basic data and using a specific processing algorithm, the actual optimal exposure energy corresponding to the currently changed mask is obtained, so that subsequent batches can perform the lithography process according to the current optimal exposure energy. By introducing basic data such as the ideal critical dimension of the mask pattern and the mask transmittance in the process of obtaining the actual optimal exposure energy corresponding to the currently changed mask, this application can effectively compensate for the optimal exposure energy corresponding to the old version of the mask, making the wafer lithography outgoing value (the actual optimal exposure energy corresponding to the changed mask) more accurate, improving the overlay accuracy of the lithography process, saving time and effort, improving the lithography efficiency, and reducing the lithography cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0026] Figure 1 It is a flowchart of the advanced process control method for dynamically correcting the optimal exposure energy of the lithography process in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0027] The following will clearly and completely describe the technical solutions in this application in conjunction with the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of this application. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.
[0028] In the description of this application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of this application. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0029] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "linkage" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can also be the communication inside two components. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.
[0030] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.
[0031] The embodiment of the present application provides an advanced process control method for dynamically correcting the optimal exposure energy of a lithography process, referring to Figure 1 , Figure 1 is a flowchart of the advanced process control method for dynamically correcting the optimal exposure energy of the lithography process in the embodiment of the present invention. The advanced process control method for dynamically correcting the optimal exposure energy of the lithography process includes:
[0032] First, execute step S1: According to the mask plate corresponding to the lithography machine stage and the film layer to be lithographed, collect the basic data of the lithography process. The lithography basic data at least includes: the ideal critical dimension of the mask plate pattern, the light transmittance of the mask plate, and the mask error enhancement factor.
[0033] Preferably, the mask plate pattern is a trench pattern, a line pattern, and a hole pattern.
[0034] In this embodiment, taking the mask plate pattern as an example of a line pattern, the following steps are continued.
[0035] Then, execute step S2: Feed back the lithography basic data to the advanced process control system.
[0036] Next, execute step S3: Use the process control system to obtain the current optimal exposure energy and feed back the current optimal exposure energy to the lithography machine stage.
[0037] Preferably, step S3 specifically includes:
[0038] Step S3.1: Confirm whether the current batch is the first pass using the replaced mask plate;
[0039] Step S3.2: If the current batch is the first pass using the replaced mask plate, obtain the critical dimension deviation of the wafer pattern through the first calculation formula; if the current batch is not the first pass using the replaced mask plate, obtain the critical dimension deviation of the wafer pattern through the second calculation formula;
[0040] Preferably, the first calculation formula is: CD wafer diff =(CD mask target -CD mask coa )*MEEF / 4, where CD wafer diff is the critical dimension deviation of the wafer pattern; CD mask target is the ideal critical dimension of the mask pattern; CD mask coa is the actually measured critical dimension of the mask pattern; MEEF is the mask error enhancement factor.
[0041] Among them, in the first calculation formula, dividing ((CD mask target -CD mask coa )*MEEF) by 4 is the conversion from the mask layer to the wafer layer, that is, converting the critical dimension deviation of the pattern on the mask layer into the critical dimension deviation of the pattern on the wafer layer.
[0042] Furthermore, MEEF is a constant, and the value range of MEEF is 2 to 3.
[0043] Preferably, the second calculation formula is: CD wafer diff =CD wafer target -CD wafer measure , where CD wafer diff is the critical dimension deviation of the wafer pattern; CD wafer target is the ideal critical dimension of the wafer pattern; CD wafer measure is the actually measured critical dimension of the wafer pattern during the previous shipment.
[0044] Step S3.3: Obtain the current optimal exposure energy according to the ideal optimal exposure energy, the mask transmittance, and the critical dimension deviation;
[0045] Step S3.4: Feed back the current optimal exposure energy to the lithography machine stage to dynamically correct the optimal exposure energy.
[0046] Specifically, in step S3.3, the specific calculation formula for obtaining the actual optimal exposure energy according to the ideal optimal exposure energy, the mask transmittance, and the critical dimension deviation is:
[0047] E new = E old + (CD wafer diff / Slope) * (1 + R);
[0048] Wherein, E new is the actual optimal exposure energy corresponding to the reticle of the version change; E old is the optimal exposure energy corresponding to the reticle of the old version; CD wafer diff is the critical dimension deviation of the wafer pattern; Slope is a constant related to the lithography process; R is the contribution value of the reticle transmittance to the optimal exposure energy.
[0049] Furthermore, the value of R is selected according to process requirements and can be selected between 0 and 1.
[0050] Finally, perform step S4: Perform lithography on the film layer to be lithographed according to the current optimal exposure energy.
[0051] In this application, by feeding back the basic data of the lithography process collected to the advanced process control system, compensating the optimal exposure energy corresponding to the reticle of the old version according to all the basic data and using a specific processing algorithm, the actual optimal exposure energy corresponding to the reticle of the current version change is obtained, so that subsequent batches can perform the lithography process according to the current optimal exposure energy. By introducing basic data such as the ideal critical dimension of the reticle pattern and the reticle transmittance in the process of obtaining the actual optimal exposure energy corresponding to the reticle of the current version change, this application can effectively compensate the optimal exposure energy corresponding to the reticle of the old version, make the wafer lithography outgoing value (the actual optimal exposure energy corresponding to the reticle of the version change) more accurate, improve the overlay accuracy of the lithography process, save time and effort, improve the lithography efficiency, and also reduce the lithography cost.
[0052] Obviously, the above embodiments are only examples clearly described and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of this application.
Claims
1. An advanced process control method for dynamically correcting the optimal exposure energy of a photolithography process, characterized in that: include: Collect basic data of the photolithography process according to the replaced mask corresponding to the photolithography machine and the film layer to be photolithography, wherein the basic photolithography data at least includes: an ideal critical dimension of the mask pattern, a mask transmittance, and a mask error enhancement factor; Feeding back the photolithography basic data to an advanced process control system; Utilizing the process control system to obtain the current optimal exposure energy, and feeding back the current optimal exposure energy to the lithography machine; The film layer to be photolithographically processed is photolithographically processed according to the current optimal exposure energy.
2. The advanced process control method for dynamically correcting the optimal exposure energy of a photolithography process according to claim 1, characterized in that: The steps of using the process control system to obtain the current optimal exposure energy and feeding the current optimal exposure energy back to the lithography machine include: Confirm whether the current batch is the first batch of masks using the replacement mask; If the current batch is the first batch of goods delivered using the mask plate that has been changed, the critical dimension deviation of the wafer pattern is obtained by the first calculation formula; if the current batch is not the first batch of goods delivered using the mask plate that has been changed, the critical dimension deviation of the wafer pattern is obtained by the second calculation formula; Obtaining a current optimal exposure energy according to the ideal optimal exposure energy, the mask transmittance and the critical dimension deviation; The current optimal exposure energy is fed back to the photolithography machine to dynamically correct the optimal exposure energy.
3. The advanced process control method for dynamically correcting the optimal exposure energy of a photolithography process according to claim 2, characterized in that: The first calculation formula is: CD waferdiff =(CD masktarget -CD maskcoa )*MEEF / 4, where CD waferdiff CD is the critical dimension deviation of wafer pattern; masktarget The ideal critical dimension of the mask pattern; CD maskcoa is the critical dimension actually measured of the mask pattern; MEEF is the mask error enhancement factor.
4. The advanced process control method for dynamically correcting the optimal exposure energy of a photolithography process according to claim 2, characterized in that: The second calculation formula is: CD waferdiff =CD wafertarget -CD wafermeasure , among which, CD waferdiff CD is the critical dimension deviation of wafer pattern; wafertarget The ideal critical dimension for wafer patterning; CD wafermeasure It is the actual critical dimension of the wafer pattern actually measured during the last delivery.
5. The advanced process control method for dynamically correcting the optimal exposure energy of a photolithography process according to claim 2, characterized in that: According to the ideal optimal exposure energy, the mask transmittance and the critical dimension deviation, the calculation formula for obtaining the actual optimal exposure energy is: HAVE BEEN new =E old +(CD waferdiff / Slope)*(1+R); Among them, E new is the actual optimal exposure energy corresponding to the mask plate of the replacement; E old The optimal exposure energy corresponding to the old mask; CD waferdiff is the critical dimension deviation of the wafer pattern; Slope is a constant related to the photolithography process; R is the contribution value of the mask transmittance to the optimal exposure energy.
6. The advanced process control method for dynamically correcting the optimal exposure energy of a photolithography process according to claim 1, characterized in that: The mask pattern is a groove pattern, a line pattern and a hole pattern.
7. The advanced process control method for dynamically correcting the optimal exposure energy of a photolithography process according to claim 3, characterized in that: The value range of MEEF is 2 to 3.