TWI225577B - Smart overlay control - Google Patents

Abstract

An automatic method to maintain and correct overlay in the fabrication of integrated circuits is described. An overlay table is automatically generated for lots run through a process toll. An overlay correction is calculated from the overlay control table and sent to the process tool for real-time or manual overlay correction.

Description

1225577 V. Description of the invention (1) The technical field to which the invention belongs: The present invention relates to a process technology of integrated circuits, and particularly to four #? Of automatic overlay correction in the process of integrated circuits. Prior technology: Lithography is widely used in the process of integrated circuits. The following is a general lithography process: First, a first deposition layer is formed on a substrate, and a photoresist layer is coated on the first deposition layer; the photoresist layer is exposed through a photomask to perform a pattern. Transfer (Pattern Transform) to define the pattern on the first deposited layer; then, the first deposited layer is engraved with money through the exposed photoresist layer to form the pattern of the first deposited layer, and then the above steps are repeated , Forming a second deposited layer on the first deposited layer. Generally, the integrated circuit manufacturing process usually includes more than one lithography process. Therefore, in order to ensure that the integrated circuit components produced are consistent with the original design, the pattern in each lithography process must be accurately aligned; To achieve this purpose, an alignment mark is usually added to each layer to provide a reference for the alignment. As described below, a conventional block alignment mark (n b ο X i n b〇Xπ alignment mark) is described.

Page 7 1225577 Fifth, the description of the invention (2) Process, the square alignment mark is usually set at the edge of the wafer, and the square alignment mark on each deposited layer is larger than the square alignment mark on the deposited layer above it. The center position of each square alignment mark is determined by the x_y coordinate. By comparing the xy readings of the center position of each square alignment mark, the translation error of each sedimentary layer relative to other sedimentary layers can be obtained. error) 〇 In the conventional technology, every other week or every month, the technician performs manual feed back adjustment on the exposure tool according to the above translation error; however, the manual feedback adjustment The translation error cannot be corrected online in real time. Therefore, the alignment of each layer of the pattern lacks stability, which causes the exposure machine to produce unexpected translation errors. In addition, the different surface fluctuations of each deposition layer (topology), and wafer deformation caused by other processes (eg, annealing process), and other factors are accurate in alignment Impact; • Therefore, the above-mentioned problems must be solved with on-line real-time alignment correction (0 v e r 1 a y c0 r r c t i ο η) technology. In US Patent Application No. 6 2 1 8 2 0 0 B1, Che η et al. Demonstrated a method of aligning multiple layers in an automatic overlay correction using an automatic alignment bridge alignment system system). In the US Patent No. 6 1 2 7 0 7 5, H s u shows a method for checking the accuracy of a measuring instrument used to measure overlay. In U.S. Patent Application No. 6 0 2 3 3 3 8, Bare ket discloses a new

Page 8 1225577 V. Description of the invention (3) Formula 1 ignment mark pattern and measuring method ° Summary of the invention: The main purpose of the present invention is to provide an automatic execution, and Method to ensure correct alignment of each deposited layer of integrated circuit. In addition, an overlay control table (overlay control table) is also generated, which can be used for online real-time alignment control. At the same time, it can also be manually controlled. φ In this way, the present invention provides a smart overlay control system to achieve the above purpose. The smart overlay control system includes a plurality of process units, a data collection unit, a pair of position servers and a Device server; among them, the data collection unit measures an overlay error generated by executing a process for a process performed by a process unit; the registration server calculates the above-mentioned registration error, and The registration error is transmitted to the operator, whereby the operator can perform manual overlay correction; on the other hand, the registration server can transmit the registration error to an intelligent registration control server (Smart overlay control servo). Therefore, the intelligent registration control server can generate a pair of position control tables for each process. At the same time, the device server executes one process for each process unit to access the previous layer. The correction value of the sedimentary layer (correction va 1 ue) and the fine-tuning value (fi ne

Page 9 1225577 V. Description of the invention (4) Tuning value), to calculate an overlay correct i on value of the process, and then to send the jfcb alignment correction value to the implementation of the process Process unit. In addition, in order to achieve the purpose of automatic execution and at the same time ensure that the deposited layers of the integrated circuit are correctly aligned; the intelligent alignment control system of the present invention can automatically generate a pair of alignment control tables for a series of processes in a process unit ; At the same time, a pair of alignment correction values are calculated according to the above-mentioned alignment control table, so as to provide the above-mentioned process unit for online real-time alignment correction, or manual alignment correction by the operator. The advantages and spirit of the present invention can be further understood through the following detailed description of the invention and the attached drawings. Embodiments: The present invention relates to an intelligent alignment control system for registering alignment errors and providing real-time online alignment feedback adjustment. The system also provides a solution for solution, co-integrated production, and line (foundry fabrication mixing). The method of run), that is, the processes of different forms or different alignment corrections can be centrally controlled by the system of the present invention. As shown in the first figure, it is a flowchart of the alignment control of the intelligent alignment control system of the present invention. First, as in step 10, the wafer is sent to the system; In-line Equipment Servo 14 Confirm the parameters of the process to be performed; such as: alignment correction value, exposure energy and focus offset, etc .; and enter this process parameters into an exposure machine, that is,

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The process unit 16 shown in the figure is for performing a lithography process. Box 2 0 in the figure is the intelligent alignment of the present invention 兮 ®- 西 次 姓 隹 隹-: Data search of one of the alignment control systems μ τ τ ν Alignment measuring device (Ο v e r 1 a y

Measurement Tool) 2 ^. A, · 0, n, ^ T position analysis server (Overlay

Analysis Servo) 24; Among them, the material #, Βί θ alignment measurement device 22 measures the alignment marks of each deposited layer, and the alignment analysis server 24 captures the measurement data of the alignment measurement device 22, thereby Raw data is formed; the above-mentioned data collection unit 20 is connected to the data execution unit 30 to provide data. The data execution unit 30 includes a pair of bit tool servers (〇verlay

Tool Servo) 32 and a process information server (Lot Information Servo) 34; among them, the alignment tool server 32 captures measurement data from the alignment measuring device 22, filters abnormal measurement data and transmits the measurement data To a Smart Overlay Control Servo, 40, at the same time, the registration tool server 32 can also send measurement data to a Lots Tracking System (not shown), such as PR OM IS. The intelligent alignment control server 40 is for each type of process, and automatically generates a corresponding alignment control table; that is, each alignment control table is for a specific lithography technology, a specific deposition layer and a The combination of $ for a specific exposure machine; and the alignment state C η of each sedimentary layer is paid according to the positive value of the alignment bridge of the previous sedimentary layer plus the trimming value of the previous sedimentary layer. Table 1-1 is a calculation mode for the adjustment value of an intelligent lithography alignment control.

Page 11 1225577 V. Description of the invention (6) Process η Cn = Pn + Fn-1 On Rn η =: 1 Cl = Pl + k 01 Rl = K-01 η =: 2 C2 = P2 + F1 02 R2 = Fl -02 η = = 3 C3 = P3 + F2 03 R3 = F2-03 n =: 4 C4-P4 + F3 04 R4 = F3-04 η:: 5 C5 two P5 + F4 05 R5 = F4-05 η:: 6 C6-P6 + F5 06 R6 = F5-06 η = = k Ck = Pk + Fk-l Ok Rk Two Fk- 1 -〇k η: = k + 1 Ck + 1 Two Pk + l + Fk 〇k + l Rk + l = Fk-0k + l Process η Fn η: = 1 F1 = R1 η: = 2 F2 = l / 2 氺 (R1 + R2) η:: 3 F3 = l / 3 氺 (R1 + R2 + R3) η: = 4 F4 = 1/3 * (R2 + R3 + R4) η: = 5 F5 two 1/3 氺 （R3 + R4 + R5) η: = 6 F6 = l / 3 氺 （R4 + R5 + R6) η: = k Fk = l / 3 * (Rk-2 + Rk-l + Rk) η: = k + l Fk + l = l / 3 * (Rk -1 + R2 + Rk + 1) where , Cn refers to the alignment correction value of the ηth process; ρ η refers to the alignment correction value of the η-1st process, P 1 = 0; 〇η refers to the alignment measurement error value; Rn refers to the alignment Residual error value

Page 121225577 V. Description of the invention (7) F η refers to the fine-tuning value obtained according to the intelligent alignment control system of the present invention. The fine-tuning value F 1 in the first process is the registration residual error value of the process. R1; and the fine-tuning value F 2 of the second process is the average of the residual error value R 2 of this process and the residual error value R 1 of the previous process; the fine-tuning value of each subsequent process is the average value of that process. The alignment residual error value is the same as that of the previous two processes. Κ refers to the average process deviation value, and in the first process, κ is set to 0 °. In addition, the value of η is obtained from the process information server 3 4; if manual alignment correction is performed, the above The alignment control table is transmitted to the process information server 3 4; otherwise, if automatic alignment correction is performed, the alignment control table is transmitted to the intelligent alignment control server 40. The online device server 14 obtains the alignment correction value Pη and the fine-tuning value Fn-: l of the previous process from the intelligent alignment control server 40 to calculate the alignment correction value C η of the process; Then, the alignment positive value C η is transmitted to the processing unit 16; then, the alignment correction value Cn is transmitted to the intelligent alignment control server 40 as the Pn of the next process. The technology of the present invention can be applied to a single alignment mark system (Sing 1 e A 1 ignment Mark System), or a multiple alignment mark system (Multiple Alignment Mark System); in a multiple alignment mark system, because Each deposited layer has its own alignment mark; therefore, the Pn value is set to 0, that is, regardless of the positive value of the alignment bridge of the previous process. As shown in the second figure, it is a flowchart of a process unit to perform a process and match the intelligent alignment control system of the present invention; as shown in step 101, if the

Page 13 1225577 V. Description of the invention (8) The process unit 16 (refer to the first figure) is the first time to execute a specific type of process, such as step 103, a process alignment control table will be generated, of which, P 1 = 0, and then enter step 105; otherwise, if the process unit 16 is not performing a new process, it will directly enter step 105. In step 105, the online device server 14 obtains the alignment correction value and fine-tuning value of the previous process from the intelligent alignment control server 40; and the intelligent alignment control server 40 is self-aligned The tool server 32 obtains the alignment control table; then, in step 107, the online device server 14 calculates the alignment correction value Cn of the process, and transmits Cn to the process unit 16. As in step 10, the processing unit 16 executes the process according to the above Cn value. At the same time, as in step 11, the data collection system 20 measures the registration mark for the process and transmits the measurement data to the The bit tool server 32 updates the registration control table. With the intelligent alignment control system of the present invention, the time spent in each process can be reduced, and the burden on process engineers is reduced. In actual testing, the alignment measurement value of more than 25% has an improvement of more than three standard deviations. ; At the same time, the redo ratio is also reduced from 0.5% to below 0.3 ° / 〇 due to registration errors. The above is a detailed description of the present invention using preferred embodiments, rather than limiting the scope of the present invention, and those skilled in the art will understand that appropriate changes and adjustments will still be made without departing from the spirit of the present invention. Without departing from the spirit and scope of the invention.

Page 14 1225577 Simple illustration of the diagram Simple illustration of the diagram: The first diagram is a flowchart of the alignment control of the intelligent alignment control system of the present invention. The second diagram is a flow chart of a process performed by a process unit and matched with the intelligent alignment control system of the present invention. Description of drawing number: 4 1i 0 server 6 server .-_ Set yuan installation order up-trip line system 2 yuan single set search data registration measurement device 2 2 registration analysis server 2 4 data execution unit 3 0 registration tool server 3 2 Process information server 3 4 Intelligent registration control server 4 0

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Claims (1)

1225577 6. Scope of patent application Patent scope: 1. An alignment control system, including: a plurality of process units; a data collection unit for measuring the alignment error value produced by a process unit in a process; a pair Positioning tool server for processing registration error data and transmitting the registration error data to an operator for manual alignment correction. At the same time, the registration error data can also be transmitted to an intelligent registration control. A server to automatically perform alignment bridge alignment; the intelligent alignment control server, which generates a pair of alignment control tables for each process, and a device server, which is used for each process The intelligent alignment control server captures an alignment correction value and a trim value of a previous process, thereby calculating an alignment correction value of the process, and transmits the alignment correction value to the relevant process unit. 2. The registration control system of item 1 in the scope of patent application, wherein the alignment correction value of one of the deposited layers formed during the process of the process unit is equal to the alignment of a deposited layer before the deposited layer The correction value is added to the fine-tuning value of the previous deposited layer, wherein the fine-tuning value is equivalent to the average of the alignment errors of the previous series of processes. 3. The registration control system according to item 2 of the scope of patent application, wherein the registration control system is matched with a multiple registration mark system, and for the process of the process unit, the deposition layer is The registration error value is set to zero. Page 16 1225577 6. Scope of patent application 4. For example, the registration control system of the first patent application scope, wherein the registration control table is a combination of a specific lithography technology, a specific deposition layer and a specific exposure machine. 5. The registration control system of item 1 of the patent application scope, wherein the registration control system is matched to a single registration mark system. 6. A method of alignment control, including: automatically generating a pair of alignment control tables for a series of processes of a process unit; and a correction value, and the alignment correction value of the process sheet is added in real time, and the value is added to the The previous layer is in the previous series. The registration control process unit performs the registration error value. The registration control and a specific exposure machine are set. The registration control automatically calculates a pair by the registration control table. The alignment correction value is transmitted to the process unit. 7. As for the alignment control method of the 6th scope of the patent application: For this process, one of the deposited layers formed is equal to the fine-tuning value of the alignment correction deposited layer of a deposited layer before the deposited layer. The fine-tuning value is the average of the equivalent range readings. 8. The registration control method according to item 7 of the scope of patent application. The system is equipped with a multiple registration mark system, and for this process, the deposition layer before the deposition layer is set to zero. 9. The registration control method according to item 6 of the scope of patent application is a combination of a specific lithography technique and a specific deposition layer. 10. The registration control method according to item 6 of the patent application scope is matched to a single registration mark system. Page 17 1225577 6. Scope of patent application 11. A method for registration control, comprising: automatically generating a pair of registration control tables for a series of processes of a process unit; and automatically calculating a pair of registrations using the registration control table The alignment correction value is used to perform a manual alignment correction process or an instant alignment correction process. 1 2. According to the registration control method of item 11 in the scope of patent application, wherein for the process of the process unit, the alignment correction value of a deposited layer is equal to that of a deposited layer before the deposited layer. The alignment correction value is added to the fine adjustment value of the previous deposited layer, wherein the fine adjustment value is equivalent to the average of the alignment errors of the previous series of processes. 13. The registration control method according to item 12 of the scope of patent application, wherein the registration control system is equipped with a multiple registration mark system, and for the process of the process unit, the deposition layer is sunk before The registration error value of the stack is set to zero. 14. The registration control method according to item 11 of the scope of patent application, wherein the registration control table is directed to a combination of a specific lithography technique, a specific deposition layer and a specific exposure machine. 15. The registration control method according to item 11 of the patent application scope, wherein the registration control system is matched to a single registration mark system. 16. A method of alignment control, comprising: after using an exposure machine to perform an exposure process, measuring an alignment error value of the exposure process; for a series of exposure processes performed with the exposure machine, using each of the The alignment error value of the exposure process and the deposition layer information of the previous process are automatically Page 18 1225577 6. The patent application scope generates a pair of registration control table; and the pair of registration correction value is automatically calculated by the registration control table, and a manual registration correction process or an instant registration correction is performed accordingly. Process. 1 7. The alignment control method according to item 16 of the scope of patent application, wherein for the process of the process unit, the alignment correction value of a deposited layer is equal to that of a deposited layer before the deposited layer. The alignment correction value is added to the fine adjustment value of the previous deposited layer, wherein the fine adjustment value is equivalent to the average of the alignment errors of the previous series of processes. 18. The registration control method according to item 17 of the scope of patent application, wherein the registration control system is matched with a multiple registration mark system, and φ is performed on the process unit. For this process, the deposition layer is one layer before The registration error value of the deposited layer is set to zero. 19. The registration control method according to item 16 of the patent application scope, wherein the registration control table is directed to a combination of a specific lithography technique, a specific deposition layer and a specific exposure machine. 20. The registration control method according to item 16 of the patent application scope, wherein the registration control system is matched to a single registration mark system.