Method for pre-compensation of overlay accuracy difference between lithography machines

Abstract

The application provides a method for pre-compensation of overlay accuracy difference between lithography machines, comprising: step one, obtaining overlay accuracy historical data of a current layer of a current batch of wafers relative to a previous layer of the wafers, according to material properties and functional properties of the current layer and the previous layer; step two, deducting overlay accuracy compensation data used when the current layer is lithographed by the same lithography machine as the previous layer from the historical data, and extracting characteristic difference of overlay accuracy between lithography machines; step three, calculating overlay accuracy compensation data required for lithography of the current layer of the current batch of wafers by the lithography machine other than the one used for the previous layer, according to the characteristic difference of overlay accuracy between lithography machines, combined with process-related information of lithography of the previous layer and process-related information of lithography of the current layer of all wafers in a previous batch of wafers by the same lithography machine. The success rate of mixed running of lithography machines is improved, trial running and rework required for switching machines are reduced, and the capacity of lithography machines is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, in particular to a method for pre-compensation of overlay accuracy difference between lithography machines. BACKGROUND

[0002] Lithography is a process of transferring a mask pattern onto a wafer through a series of steps such as alignment and exposure. In the manufacturing process of a semiconductor, the entire manufacturing process is usually completed through a multi-layer lithography process, and how to control the position alignment of the current layer lithography pattern and the previous layer lithography pattern (pattern on the wafer) to meet the overlay accuracy requirement is a crucial step in the multi-layer lithography process. Overlay is defined as the position accuracy of the current layer pattern and the previous layer pattern in the lithography manufacturing process.

[0003] The overlay accuracy between different lithography machines will be different, which leads to the fact that some overlay accuracy control is relatively strict, and the same lithography machine (i.e. vertical machine) needs to be used for running the goods for the front and back layers, and once the machine needs to be changed, Pi-run or rework is needed, which seriously wastes the capacity of the lithography machine. SUMMARY

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a method for pre-compensation of overlay accuracy difference between lithography machines, which is used to solve the problem of Pi-run or rework affecting the capacity of the lithography machine when the front and back layers need to be changed.

[0005] To achieve the above-mentioned purpose and other related purposes, the present application provides a method for pre-compensation of overlay accuracy difference between lithography machines, comprising:

[0006] Step one, according to the material properties and functional properties of the current layer and the previous layer of the current batch of wafers, obtaining the overlay accuracy historical data of the current layer relative to the previous layer when the current layer is subjected to lithography by changing the machine;

[0007] Step two, deducting the overlay accuracy compensation data used when the current layer is subjected to lithography by the same lithography machine relative to the previous layer from the historical data, and extracting the characteristic difference of the overlay accuracy between lithography machines;

[0008] Step three, according to the characteristic difference of the overlay accuracy between lithography machines, combining the process-related information of the lithography of the previous layer and the process-related information of the lithography of the current layer of all wafers in the previous batch of wafers by the same lithography machine, and calculating the overlay accuracy compensation data required for the lithography of the current layer relative to the previous layer by changing the machine.

[0009] Preferably, the previous layer and the current layer correspond to the same layer of the same device product, similar layers of the same device product, or similar layers of the same process platform.

[0010] Preferably, the similar layer is similar to the current layer or the previous layer in material properties or functions.

[0011] Preferably, the overlay accuracy compensation data used in the photolithography of the current layer by the same photolithography machine is calculated according to the overlay accuracy measurement data of the previous layer, the process parameters in the photolithography of the previous layer, and the process related information of the photolithography of the current layer on the previous batch of wafers.

[0012] Preferably, the calculation is performed by an advanced process control system.

[0013] Preferably, the calculation process compensates for the system error of the advanced process control system itself.

[0014] Preferably, the compensation value of the system error is a fixed value.

[0015] Preferably, in step three, the error of the photolithography machine itself is introduced into the calculation by analyzing the process related information of the photolithography of the previous layer and the process related information of the photolithography of the current layer on all wafers in the previous batch of wafers by the same photolithography machine.

[0016] As described above, the pre-compensation method for the overlay accuracy difference between photolithography machines provided by the present application has the following beneficial effects: the overlay accuracy compensation value required when the photolithography of the previous and subsequent layers needs to be switched is predicted, the success rate of mixed running of photolithography machines is improved, the trial running and rework required for switching are reduced, and the production capacity of photolithography machines is improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art of the present application, the drawings needed in the specific embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can obtain other drawings without creative labor based on these drawings.

[0018] Figure 1 The flowchart of the pre-compensation method for the overlay accuracy difference between photolithography machines provided by the embodiments of the present application is shown. DETAILED DESCRIPTION

[0019] The embodiments of the present application are described below through specific examples. Those skilled in the art can easily understand other advantages and effects of the present application from the disclosure. The present application can also be implemented or applied by different specific embodiments, and the details in the description can be modified or changed based on different views and applications without departing from the spirit of the present application.

[0020] The technical solutions in the present application will be described clearly and completely in combination with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application.

[0021] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are merely for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0022] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements, it can be wireless connection, or it can be wired connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0023] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0024] Please refer to Figure 1 , which shows a flowchart of a pre-compensation method for overlay precision difference between lithography machines provided by an embodiment of the present application.

[0025] As Figure 1 shown, the pre-compensation method for overlay precision difference between lithography machines includes the following steps:

[0026] Step one, according to the material properties and functional properties of the current layer and the previous layer of the current batch of wafers, the overlay precision historical data of the current layer implemented by the previous layer is obtained;

[0027] Step two, deducting the overlay precision compensation data used when the same lithography machine is used to implement lithography on the current layer from the historical data, extracting the characteristic difference of the overlay precision between lithography machines;

[0028] Step three, according to the characteristic difference of overlay accuracy between different lithography machines, combining the process related information of the lithography of the previous layer and the process related information of the lithography of the current layer of all wafers in the previous batch of wafers by the same lithography machine, the overlay accuracy compensation data required for the lithography of the current layer by the transfer machine is calculated.

[0029] In step one, according to the material properties and functional properties of the current layer and the previous layer of the current batch of wafers, the overlay accuracy data of the lithography of the previous layer and the current layer on different lithography machines is found in the overlay accuracy history data. The corresponding to the previous layer and the current layer can be the same layer of the same device product, similar layers of the same device product or similar layers of the same process platform, which are similar to the material properties of the current layer or the previous layer or similar in function.

[0030] In step two, the overlay accuracy compensation data used when the current layer is lithographed by the same lithography machine is calculated according to the overlay accuracy measurement data of the previous layer, the process parameters when the previous layer is lithographed, and the process related information of the lithography of the current layer of the previous batch of wafers.

[0031] As an example, the above calculation process can be performed by an advanced process control (APC) system. When the above calculation process is performed by using the advanced process control system, the system error of the advanced process control system itself is considered, the system error of the advanced process control system itself is compensated to reduce the influence of the system error of the advanced process control system itself on the overlay accuracy compensation data, and the system error compensation value is a fixed value which can be obtained by statistical analysis of historical data or calculated by constructing an overlay accuracy compensation model.

[0032] In step three, by analyzing the process related information of the lithography of the previous layer and the process related information of the lithography of the current layer of all wafers in the previous batch of wafers by the same lithography machine, the error of the lithography machine itself can be introduced into the calculation of the overlay accuracy compensation data required for the lithography of the current layer by the transfer machine.

[0033] As an example, the error of the lithography machine itself may, for example, include the following parameters: X, Y direction displacement (Trans_X, Trans_Y), wafer magnification or reduction (Exp_X, Exp_Y), wafer rotation (Wfr_RotX, Wfr_RotY), exposure field magnification or reduction (Sht_MagX, Sht_MagY) and exposure field rotation.

[0034] Through experimental measurement, the pre-compensation method of overlay accuracy difference between photolithography machines provided by the embodiment of the application can improve the overlay accuracy of the current layer by 30% and 6% in X and Y directions respectively compared with the prior art, can effectively improve the success rate of photolithography machine mixed running, and reduce the trial running and rework required by the transfer machine.

[0035] It should be noted that the diagram provided in the embodiment only illustrates the basic concept of the application in a schematic manner, only the components related to the application are shown in the diagram, and the diagram is not drawn according to the number, shape and size of the components in actual implementation. The type, number and proportion of each component in actual implementation can be arbitrarily changed, and the component layout type can be more complex.

[0036] In summary, the pre-compensation method of overlay accuracy difference between photolithography machines provided by the application predicts the overlay accuracy compensation value required when the photolithography of the front and back layers needs to be transferred, improves the success rate of photolithography machine mixed running, reduces the trial running and rework required by the transfer machine, and improves the photolithography machine capacity. Therefore, the application effectively overcomes the various shortcomings in the prior art and has high industrial utilization value.

[0037] The above embodiments only illustratively explain the principles and effects of the application, and are not used to limit the application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical idea disclosed by the application should be covered by the claims of the application.

Claims

1. A pre-compensation method for overlay accuracy differences between lithography machines, characterized in that, The method includes: Step 1: Based on the material and functional properties of the current layer and the previous layer of the current batch of wafers, obtain historical data on the overlay accuracy of photolithography performed on the current layer relative to the previous layer. Step 2: Subtract the overlay accuracy compensation data used when the current layer was lithographically ... Step 3: Based on the characteristic differences in overlay accuracy between the lithography machines, and combining the process-related information of performing lithography on the previous layer and the process-related information of performing lithography on the current layer of all wafers in the previous batch using the same lithography machine, calculate the overlay accuracy compensation data required for performing lithography on the current layer relative to the previous layer transfer machine.

2. The method according to claim 1, characterized in that, The layers corresponding to the previous and current layers are the same layer of the same device product, the similar layer of the same device product, or the similar layer of the same process platform.

3. The method according to claim 2, characterized in that, The similar layer has similar material properties or functions to the current layer or the previous layer.

4. The method according to claim 1, characterized in that, The overlay accuracy compensation data used when performing lithography on the current layer using the same lithography machine is calculated based on the overlay accuracy measurement data of the previous layer, the process parameters when performing lithography on the previous layer, and the process-related information of performing lithography on the current layer of the previous batch of wafers.

5. The method according to claim 4, characterized in that, The calculations are performed using an advanced process control system.

6. The method according to claim 5, characterized in that, The calculation process compensates for the system errors of the advanced process control system itself.

7. The method according to claim 6, characterized in that, The compensation value for the system error is a fixed value.

8. The method according to claim 1, characterized in that, In step three, by analyzing the process-related information of the previous layer's photolithography and the process-related information of the current layer's photolithography performed on all wafers in the previous batch using the same photolithography machine, the error of the photolithography machine itself is incorporated into the calculation.

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