Machine overlay monitoring method, storage medium and system

Abstract

The present invention discloses a machine overlay monitoring method, comprising the following steps: the KT machine takes a photo of the overlaymark; the taken photo is compared with the pre-stored photo, if the contrast exceeds the specified threshold, the mark is judged to be normal, and the KT measurement is performed normally; if the contrast is less than or equal to the specified threshold, the mark is judged to be wrong, and the measurement based on the image is returned. The present invention can effectively monitor the 8um shift error, avoid misjudgment of the actual situation of online goods running away, and cause the problematic wafer to flow out, resulting in irreparable losses.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuit manufacturing, and in particular to a machine overlay monitoring method, as well as a computer-readable storage medium for executing the steps in the machine overlay monitoring method and a computer system for executing the machine overlay monitoring method. Background Art

[0002] During the alignment process, the ASML scanner will have an 8um shift error. That is, the current layer will have an 8um shift compared to the previous overlay layer. However, the current KT overlay measurement cannot identify the overlay shift error. It has been checked under an optical microscope that the current wafer has an 8um shift. However, during the KT overlay measurement, there are still overlay measurement values ​​and measurement maps. This leads to a misjudgment of the actual situation of online product delivery, causing problematic wafers to flow out, resulting in irreparable losses.

[0003] The KT overlay measurement is based on the convolution summation operation of the image. The machine will calculate the center position of the previous layer mark and the current layer mark respectively, and then obtain the overlay value between the two layers. Figure 1 As shown, if an 8um error occurs, the machine will Figure 2 The position of marker 2 in the Figure 1 Mark 1 in the figure still performs convolution calculation and obtains the wrong overlay value. Summary of the invention

[0004] A series of simplified concepts are introduced in the Summary of the Invention, which are all simplifications of the prior art in the field, and will be further described in detail in the Detailed Description of the Invention. The Summary of the Invention of the present invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0005] The technical problem to be solved by the present invention is to provide a machine overlay monitoring method which can timely and accurately detect overlay errors.

[0006] In order to solve the above technical problems, the present invention provides a machine overlay monitoring method, comprising the following steps:

[0007] S1, KT machine takes overlay mark photos;

[0008] S2, compare the grayscale of the captured photo with the pre-stored photo, mainly comparing the peak area of ​​the mark. If the contrast exceeds the specified threshold, the mark is judged to be normal and the KT measurement is performed normally; if the contrast is less than or equal to the specified threshold, the mark is judged to be wrong and the measurement is returned to the image-based measurement.

[0009] Wherein, in the machine overlay monitoring method, if the contrast is less than or equal to a specified threshold, the captured photo and the pre-stored photo are further subjected to binary image grayscale value comparison.

[0010] When comparing the grayscale values ​​of the binary image, if 4 peaks are obtained in both the X and Y directions;

[0011] Then, the center position difference between the first grayscale peak and the third grayscale peak in the X and Y directions, and the center position difference between the second grayscale peak and the fourth grayscale peak in the X and Y directions are calculated respectively, and the overlay values ​​in the X and Y directions are obtained respectively.

[0012] When comparing the grayscale values ​​of the binary image, if four grayscale peaks are obtained in only one of the X and Y directions and only two grayscale peaks are obtained in the other direction, it is determined that an error occurs in the direction in which only two grayscale peaks appear, and the machine reports to the EAP that an FDC hold 8um error has occurred.

[0013] When comparing the grayscale values ​​of the binary image, if less than or equal to three grayscale peaks are obtained in both the X and Y directions, the mark is judged to be damaged.

[0014] The present invention also provides a computer-readable storage medium for executing the steps in the machine overlay monitoring method, which can be implemented by computer programming technology and then stored in a computer-readable storage medium of the prior art such as a hard disk and a U disk.

[0015] The present invention also provides a computer system for executing the machine overlay monitoring method, which is implemented by using existing computer hardware through computer programming technology.

[0016] After the KT machine takes a photo of the overlay mark, the present invention first performs image judgment, and compares the image stored in the recipe with the currently taken image using a binary image. If the contrast exceeds a certain threshold, the mark is considered normal, no 8um error occurs, and the KT measurement is performed normally. If it is lower than the set threshold, the mark is considered to have a problem, and the measurement returns to the image-based measurement.

[0017] Because the image size is fixed and the magnification is fixed, 1 pixel corresponds to 80nm. Based on the grayscale value of the image, the grayscale peaks in the X / Y directions can be obtained. Based on the number of peaks in the X / Y directions, it can be determined whether to output a rougher measurement value or report an alarm. Therefore, the present invention can effectively monitor the 8um shift error, avoid misjudgment of the actual situation of online goods running away, and cause problematic wafers to flow out, resulting in irreparable losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings of the present invention are intended to illustrate the general characteristics of the methods, structures and / or materials used in specific exemplary embodiments of the present invention, and to supplement the description in the specification. However, the drawings of the present invention are schematic diagrams not drawn to scale, and thus may not accurately reflect the precise structure or performance characteristics of any given embodiment, and the drawings of the present invention should not be interpreted as limiting or restricting the range of values ​​or properties covered by the exemplary embodiments of the present invention. The present invention is further described in detail below in conjunction with the drawings and specific embodiments:

[0019] Figure 1 This is a schematic diagram of the overlay of 8um shift wafer produced by the existing technology. Figure 1 .

[0020] Figure 2 This is a schematic diagram of the overlay of 8um shift wafer produced by the existing technology. Figure 2 .

[0021] Figure 3 Schematic diagram of the third embodiment of the present invention. DETAILED DESCRIPTION

[0022] The following describes the implementation methods of the present invention through specific specific embodiments, and those skilled in the art can fully understand other advantages and technical effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through different specific implementation methods, and the details in this specification can also be applied based on different viewpoints, and various modifications or changes can be made without deviating from the overall design concept of the invention. It should be noted that the following embodiments and the features in the embodiments can be combined with each other in the absence of conflict. The following exemplary embodiments of the present invention can be implemented in a variety of different forms and should not be interpreted as being limited to the specific embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of the present invention thorough and complete, and to fully convey the technical solutions of these exemplary specific embodiments to those skilled in the art.

[0023] First embodiment;

[0024] The present invention provides a machine overlay monitoring method, comprising the following steps:

[0025] S1, KT machine takes overlay mark photos;

[0026] S2, compare the captured photo with the pre-stored photo. If the contrast exceeds a specified threshold, the mark is judged to be normal and KT measurement is performed normally;

[0027] If the contrast is less than or equal to the specified threshold, it is marked as an error and returns to image-based measurement.

[0028] Second embodiment;

[0029] The present invention provides a machine overlay monitoring method, comprising the following steps:

[0030] S1, KT machine takes overlay mark photos;

[0031] S2, compare the captured photo with the pre-stored photo. If the contrast exceeds a specified threshold, the mark is judged to be normal and KT measurement is performed normally;

[0032] If the contrast is less than or equal to the specified threshold, the grayscale values ​​of the captured photo and the pre-stored photo are compared. If four peaks are obtained in both the X and Y directions;

[0033] Then, the center position difference between the first grayscale peak and the third grayscale peak in the X and Y directions, and the center position difference between the second grayscale peak and the fourth grayscale peak in the X and Y directions are calculated respectively, and the overlay values ​​in the X and Y directions are obtained respectively.

[0034] Third embodiment;

[0035] The present invention provides a machine overlay monitoring method, comprising the following steps:

[0036] S1, KT machine takes overlay mark photos;

[0037] S2, compare the captured photo with the pre-stored photo. If the contrast exceeds a specified threshold, the mark is judged to be normal and KT measurement is performed normally;

[0038] refer to Figure 3 As shown, if the contrast is less than or equal to the specified threshold, the captured photo is compared with the pre-stored photo in binary image grayscale value. If only four grayscale peaks are obtained in one of the two directions of X and Y, and only two grayscale peaks are obtained in the other direction, it is determined that an error occurs in the direction where only two grayscale peaks appear, and the machine reports the FDC hold8um error to the EAP.

[0039] Fourth embodiment;

[0040] The present invention provides a machine overlay monitoring method, comprising the following steps:

[0041] S1, KT machine takes overlay mark photos;

[0042] S2, compare the captured photo with the pre-stored photo. If the contrast exceeds a specified threshold, the mark is judged to be normal and KT measurement is performed normally;

[0043] If the contrast is less than or equal to the specified threshold, the grayscale values ​​of the captured photo and the pre-stored photo are compared. If less than or equal to three grayscale peaks are obtained in both the X and Y directions, the mark is judged to be damaged.

[0044] Fifth embodiment;

[0045] The present invention provides a computer-readable storage medium for executing the steps in the machine overlay monitoring method described in any of the above embodiments, which can be implemented by computer programming technology and then stored in a computer-readable storage medium of the prior art such as a hard disk and a USB flash drive.

[0046] Sixth embodiment;

[0047] The present invention provides a computer system for executing the machine overlay monitoring method described in any of the above embodiments, which is implemented by using existing computer hardware through computer programming technology.

[0048] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. It will also be understood that, unless expressly defined herein, terms such as those defined in general dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and not interpreted in an ideal or overly formal sense.

[0049] The present invention has been described in detail above through specific implementation modes and embodiments, but these do not constitute limitations of the present invention. Without departing from the principles of the present invention, those skilled in the art may also make many variations and improvements, which should also be regarded as the protection scope of the present invention.

Claims

1. A machine overlay monitoring method, characterized in that: The following steps are involved: S1, KT machine takes overlay mark photos; S2, compare the captured photo with the pre-stored photo. If the contrast exceeds a specified threshold, the mark is judged to be normal and KT measurement is performed normally; If the contrast is less than or equal to the specified threshold, the grayscale values ​​of the captured photo and the pre-stored photo are compared; if 4 peaks are obtained in both the X and Y directions; Then calculate the center position difference between the first grayscale peak and the third grayscale peak in the X and Y directions, and the center position difference between the second grayscale peak and the fourth grayscale peak in the X and Y directions, and obtain the overlay values ​​in the X and Y directions respectively; When comparing the grayscale values ​​of the binary image, if only four grayscale peaks are obtained in one of the two directions, X and Y, and only two grayscale peaks are obtained in the other direction, it is determined that an error has occurred in the direction where only two grayscale peaks appear, and the machine reports to the EAP that an FDC hold 8um error has occurred; When comparing the grayscale values ​​of the binary image, if there are less than or equal to three grayscale peaks in both the X and Y directions, it is judged that the mark is wrong and the measurement returns to the image-based measurement.

2. A computer-readable storage medium for executing the steps in the machine overlay monitoring method as claimed in claim 1.

3. A computer system for executing the machine overlay monitoring method as claimed in claim 1.

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