Pre-compensation method for alignment precision difference between photoetching machines

Abstract

The invention provides a pre-compensation method for an overlay precision difference between photoetching machines, which comprises the following steps of: 1, according to material attributes and functional attributes of a current layer and a previous layer of a current batch of wafers, acquiring overlay precision historical data of photoetching a current layer by a rotating machine relative to the previous layer; 2, deducting overlay precision compensation data adopted when the current layer is subjected to photoetching by using the same photoetching machine relative to the previous layer from the historical data, and extracting the characteristic difference of the overlay precision between photoetching machines; step 3, according to the characteristic difference of the overlay precision between photoetching machines, combining the process related information of photoetching the previous layer and the process related information of photoetching the current layer of all wafers in the previous batch by using the same photoetching machine; and measuring and calculating overlay precision compensation data required for photoetching the current layer relative to the former layer rotating machine. The success rate of mixed running of the photoetching machine is improved, trial running and reworking required by the rotating machine are reduced, and the productivity of the photoetching machine is improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a method for pre-compensating differences in overlay accuracy between lithography machines. Background Art

[0002] Photolithography is a process that transfers mask patterns to wafers through a series of steps such as alignment and exposure. In the semiconductor manufacturing process, it is usually necessary to go through multiple layers of photolithography to complete the entire manufacturing process. How to control the position alignment of the current layer of photolithography patterns with the previous layer of photolithography patterns (patterns on the wafer) to meet the requirements of overlay accuracy is a critical step in the multi-layer photolithography process. Overlay accuracy is defined as the position accuracy of the current layer pattern and the previous layer pattern in the photolithography manufacturing process.

[0003] There are differences in overlay accuracy between different lithography machines, which means that some lithography layers with strict overlay accuracy control often require the front and rear layers to be bound to the same lithography machine (i.e., a vertical machine) for shipment. Once a machine change is required, a trial run (Pi-run) or rework (Rework) is required, which seriously wastes the lithography machine's production capacity. Summary of the invention

[0004] In view of the shortcomings of the prior art described above, the purpose of the present application is to provide a method for pre-compensating the difference in overlay accuracy between lithography machines, which is used to solve the problem in the prior art that when the lithography of the front and rear layers needs to be switched, a test run or rework is required, which affects the production capacity of the lithography machine.

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

[0006] Step 1: According to the material properties and functional properties of the current layer and the previous layer of the current batch of wafers, historical data of overlay accuracy of the current layer relative to the previous layer is obtained;

[0007] Step 2: deducting the overlay accuracy compensation data used when the current layer is photolithographically processed by the same photolithography machine relative to the previous layer from the historical data, and extracting the characteristic difference of overlay accuracy between photolithography machines;

[0008] Step three, based on the characteristic differences in overlay accuracy between lithography machines, combined with the process-related information of lithography on the previous layer and the process-related information of lithography on the current layer of all wafers in the previous batch of wafers using the same lithography machine, calculate the overlay accuracy compensation data required for lithography on the current layer relative to the previous layer.

[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 has similar material properties or performs similar functions to the current layer or the previous layer.

[0011] Preferably, the overlay accuracy compensation data used when performing photolithography on the current layer using the same photolithography machine is calculated based on the overlay accuracy measurement data of the previous layer, the process parameters when performing photolithography on the previous layer, and the process-related information when performing photolithography on the current layer of the previous batch of wafers.

[0012] Preferably, the calculations are performed using 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 lithography machine itself is introduced into the measurement by analyzing the process-related information of lithography performed on the previous layer and the process-related information of lithography performed on the current layer of all wafers in a previous batch of wafers using the same lithography machine.

[0016] As described above, the pre-compensation method for the overlay accuracy difference between lithography machines provided in the present application has the following beneficial effects: predicting the overlay accuracy compensation value required when the lithography of the front and rear layers needs to be switched, improving the success rate of mixed running of lithography machines, reducing the trial runs and rework required for switching, and improving the production capacity of lithography machines. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A flow chart of a method for pre-compensating overlay accuracy differences between lithography machines provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0019] The following describes the implementation of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0020] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0021] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating directions or positional relationships, are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0022] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0023] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0024] See also Figure 1 , which shows a flow chart of a method for pre-compensating overlay accuracy differences between lithography machines provided in an embodiment of the present application.

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

[0026] Step 1: According to the material properties and functional properties of the current layer and the previous layer of the current batch of wafers, historical data of overlay accuracy of the current layer relative to the previous layer is obtained;

[0027] Step 2: deducting the overlay accuracy compensation data used when the current layer is photolithographically processed by the same photolithography machine relative to the previous layer from the historical data, and extracting the characteristic difference of overlay accuracy between photolithography machines;

[0028] Step three, based on the characteristic differences in overlay accuracy between lithography machines, combined with the process-related information of lithography on the previous layer and the process-related information of lithography on the current layer of all wafers in the previous batch of wafers using the same lithography machine, calculate the overlay accuracy compensation data required for lithography on the current layer relative to the previous layer.

[0029] In step 1, 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 previous layer and the current layer respectively implemented on different lithography machines are found in the overlay accuracy historical data. The previous layer and the current layer may correspond to the same layer of the same device product, a similar layer of the same device product, or a similar layer of the same process platform, and the similar layer has similar material properties or similar functions to the current layer or the previous layer.

[0030] In step two, the overlay accuracy compensation data used when performing photolithography on the current layer using the same photolithography machine is calculated based on the overlay accuracy measurement data of the previous layer, the process parameters when performing photolithography on the previous layer, and the process-related information when performing photolithography on 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 an advanced process control system, the system error of the advanced process control system itself is taken into account, and 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. The system error compensation value is a fixed value, which can be obtained by statistical analysis of historical data or by calculating by constructing an overlay accuracy compensation model.

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

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

[0034] Through experimental calculations, the pre-compensation method for the difference in overlay accuracy between lithography machines provided in the embodiment of the present application can improve the overlay accuracy of the lithography performed on the current layer by 30% and 6% in the X and Y directions respectively compared to the prior art, thereby effectively improving the success rate of mixed running of lithography machines and reducing the trial runs and rework required for switching.

[0035] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present application in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0036] In summary, the pre-compensation method for the overlay accuracy difference between lithography machines provided by the present application predicts the overlay accuracy compensation value required when the lithography of the front and rear layers needs to be switched, thereby improving the success rate of mixed operation of lithography machines, reducing the trial operation and rework required for switching, and improving the production capacity of lithography machines. Therefore, the present application effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0037] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present application.

Claims

1. A method for pre-compensating the difference in overlay accuracy between lithography machines, characterized in that: The method comprises: Step 1, according to the material properties and functional properties of the current layer and the previous layer of the current batch of wafers, obtaining the historical data of the overlay accuracy of the photolithography performed on the current layer relative to the previous layer; Step 2: deducting the overlay accuracy compensation data used when the current layer is photolithographically processed by the same photolithography machine relative to the previous layer from the historical data, and extracting the characteristic difference of overlay accuracy between photolithography machines; Step three, based on the characteristic differences in overlay accuracy between the lithography machines, combined with the process-related information of lithography on the previous layer and the process-related information of lithography on the current layer of all wafers in a previous batch of wafers using the same lithography machine, calculate the overlay accuracy compensation data required for lithography on the current layer relative to the previous layer.

2. The method according to claim 1, characterized in that 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.

3. The method according to claim 2, characterized in that The similar layer has similar material properties or performs similar 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 photolithography on the current layer with the same photolithography machine is calculated based on the overlay accuracy measurement data of the previous layer, the process parameters when performing photolithography on the previous layer, and the process-related information when performing photolithography 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 error of the advanced process control system itself.

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

8. The method according to claim 1, characterized in that: In step three, the error of the lithography machine itself is introduced into the measurement by analyzing the process-related information of the previous layer lithography and the process-related information of the current layer lithography of all wafers in the previous batch of wafers using the same lithography machine.

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