JP2630484B2 - Automatic misalignment management device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] In a photolithography process in the manufacture of a semiconductor device, an automatic misalignment management device for automatically managing misalignment between a resist pattern formed on a wafer and a lower layer pattern By accurately measuring the displacement between the resist pattern formed in the photolithography process and the lower layer pattern, analyzing the cause of the displacement in a short time and feeding back the information to the production line, Good quality control, and furthermore, always maintain the best performance of the misalignment management device itself,
An inspection stage for mounting a wafer, and an XY stage for moving the inspection stage in the X-Y direction, for the purpose of providing an automatic misalignment management device for improving product quality and yield. A microscope for enlarging the misregistration measurement mark formed on the wafer, photoelectric conversion means for converting an image of the misregistration measurement mark enlarged by the microscope into an electric signal, A displacement amount calculating means for receiving a luminance signal to be output and calculating a displacement amount, and a correction value calculating means for receiving a displacement amount output from the displacement amount calculating means and outputting a displacement correction value An automatic displacement management device having an automatic displacement management device having automatic device performance confirmation means for automatically confirming the performance of the automatic displacement management device. It is composed with.

[Industrial applications]

The present invention relates to an automatic misalignment management device that automatically manages misalignment between a resist pattern formed on a wafer and a lower layer pattern in a photolithography process in the manufacture of a semiconductor device.

[Conventional technology]

In recent years, 10 layers to 20 layers have been
A method of manufacturing a semiconductor device by stacking layer patterns has been used, and the size of a formed pattern has been reduced, so-called submicron patterns of 1 μm or less have been formed.

As described above, in order to manufacture a semiconductor device by stacking layers having fine patterns formed thereon in multiple layers, the patterns formed in each layer must be accurately aligned with each other. For example, in order to form a pattern on the n-th layer, first, a resist is applied thereon, and a resist pattern is formed by exposing and developing using a mask, and the n-th layer is formed using this resist pattern as a mask. However, in order to prevent the displacement of the pattern between the respective layers, a displacement occurs between the resist pattern and the pattern formed in the (n-1) th layer. You need to make sure that there are no.

Conventionally, a misregistration measurement mark is formed in a partial region of a resist pattern used for patterning the n-th layer, and is formed in a lower layer, that is, a partial region of the (n-1) -th layer pattern. A human observes the relative positional relationship with the position-displacement measurement mark using a microscope to determine whether the position deviation is good or not.

[Problems to be solved by the invention]

There is an individual difference in a method of judging good or bad by observing by a human, and it is also difficult to accurately measure the displacement amount. Therefore, it is not possible to analyze the displacement information between the resist pattern and the lower layer pattern and feed back appropriate correction information to the exposure apparatus.
There is a disadvantage that quality control of the production line is not performed well.

An object of the present invention is to eliminate this drawback, accurately measure the displacement between the resist pattern formed in the photolithography process and the lower layer pattern, and analyze the cause of the displacement in a short time. By feeding the information back to the production line, the quality of the production line can be managed well, and the performance of the misalignment management device itself can always be kept in the best condition, thereby improving the product quality and yield. An object of the present invention is to provide an automatic misalignment management device which is improved.

[Means for solving the problem]

The object is to provide an inspection stage (1) for mounting a wafer (2), an XY stage (3) for moving the inspection stage (1) in the XY directions, and the wafer (2).
A microscope (4) for enlarging the misregistration measurement mark formed on the microscope, and a photoelectric conversion means (5) for converting an image of the misregistration measurement mark enlarged by the microscope (4) into an electric signal; A luminance signal output from the photoelectric conversion means (5) is input, and a positional shift amount calculating means (6) for calculating a positional shift amount, and a positional shift amount output from the positional shift amount calculating means (6) are input. In addition, in an automatic displacement management device having a correction value calculating means (7) for outputting a displacement correction value, an automatic device performance checking means (9) for automatically checking the performance of the automatic displacement management device is provided. This is achieved by the provided automatic misalignment management device.

[Action]

FIG. 2A shows a plan view of a misalignment measurement mark, and FIG. 2B shows a cross-sectional view taken along line AA. In the figure, reference numeral 21 denotes a misregistration measurement mark formed in a partial region of the pattern of the first layer formed on the wafer 2;
Is the second layer to be patterned, and 23 is the second layer
These marks are misalignment measurement marks formed in a partial region of a resist pattern used as a mask for patterning a layer. These marks (the misalignment measurement mark 21 and the mark for patterning the second layer) are used. This is for measuring the positional deviation between the positional deviation measuring marks 23) formed in a partial area of the resist pattern used as a mask.

In the automatic misalignment management device according to the present invention, the misalignment measurement marks 21 and 23 formed on the wafer 2 are enlarged using the microscope 4 and are enlarged using the photoelectric conversion means 5 as shown in FIG. Is converted into a luminance signal as shown in FIG. FIG. 3 (a) is a plan view of the misalignment measurement mark, which is the same as the misalignment measurement mark shown in FIG. 2 (a). Third
FIG. 6B is a luminance distribution diagram on the line BB of the misalignment measurement mark. This luminance signal is input to the displacement calculating means 6, and the boundary of the displacement measurement mark is defined using the least squares method, the slicing method or the like, and the displacement is calculated.
The slicing method is, as shown in FIG. 3 (b), a method of defining a boundary portion of a misregistration measurement mark from an intersection of a luminance curve of the misregistration measurement mark and a straight line C having a constant luminance. . If the above method is used, the amount of displacement can be ± 0.02
It can be measured with an accuracy of μm.

By the way, the automatic misalignment management device according to the present invention,
Either (i) a product inspection purpose or (ii) a manufacturing device (stepper) management purpose can be selected and used.

(B) When used for product inspection purposes A resist pattern is formed on one or two wafers in one lot to create a pilot wafer, and the positional shift amount thereof is calculated by the positional shift amount calculating means 6. The correction value is input to the correction value calculation means 7, and the correction value calculation means 7 calculates a shift amount of the stage of the stepper in the X-Y direction or the rotation direction, and inputs a correction value for correcting the shift amount to the stepper. After adjusting the stepper, the photolithography process is performed on all the wafers included in the lot. The amount of misregistration of a product on which a resist pattern is formed is measured, and the variation in misregistration within a lot is fed back to a manufacturing line, which can be used to improve quality.

(B) When used for management of a manufacturing apparatus (stepper): A test wafer is used to measure the amount of misalignment of misalignment measurement marks formed on a large number of wafers, and the information is used as a correction value calculating means 7 To the stage, the orthogonality of the stepper travel, the amount of movement, the stage running accuracy such as reproducibility, the lens distortion accuracy due to the effect of lens distortion, the alignment accuracy when placing the wafer on the stage, etc. And outputs a correction signal to the stepper to adjust the stepper.

Further, the automatic misalignment management device according to the present invention is provided with an automatic device performance check means 9 for measuring the absolute value of the measured value, the reproducibility accuracy, the shape of the luminance signal, and the shape of the wafer using the reference wafer. Always keep the automatic misalignment management device in the best condition by automatically checking the performance of the automatic misalignment management device itself such as positioning accuracy, inspection stage feeding accuracy, transport reliability, anti-vibration effect, dust adhesion, etc. Can be.

〔Example〕

Hereinafter, an automatic displacement management apparatus according to an embodiment of the present invention will be described with reference to the drawings.

See FIG. 1. FIG. 1 shows a functional block diagram of the automatic misalignment management device. In the figure, 1 is an inspection stage on which the wafer 2 is mounted, 3 is an XY stage that moves the inspection stage in the XY directions, 4 is a microscope, and 5 is observed by the microscope 4. Reference numeral 6 denotes a photoelectric conversion unit for converting the mark image for measuring the displacement into an electric signal. Reference numeral 6 denotes a luminance signal output from the photoelectric conversion unit 5, and the position is determined by using a geometric method such as a slice method or a least square method. There is a displacement amount calculating means for calculating a displacement amount by defining a boundary portion of the displacement measurement mark, and 7 is provided with a displacement information output from the displacement amount calculating means 6 and inputted to a stepper used for exposure. Correction value calculation means 9 outputs various correction values. Reference numeral 9 measures the amount of displacement using a reference wafer, and performs the performance of the automatic displacement control device itself, for example, the absolute value accuracy and reproducibility of the measured values. Accuracy, shape of luminance signal Wafer positioning accuracy of the inspection stage feeding accuracy, transport reliability, a vibration damping effect, automatically check device performance automatic check means dust deposition or the like, 8
Is a cathode ray tube (CRT) that displays the displacement on the screen.
Reference numeral 0 denotes a transfer unit that places the wafer 2 on the inspection stage 1, and reference numeral 11 denotes a wafer cassette that stores the wafer.

When using this device for product inspection purposes, first
A resist pattern is formed on one or two of the wafers in the lot, placed on the inspection stage 1 using the transporting means 10, and formed on the resist pattern and the misalignment measurement mark formed in the lower layer. The deviation from the position deviation measurement mark is calculated using the position deviation amount calculating means 6, and the information is input to the correction value calculating means 7, and the XY direction, the rotation direction, etc., of the stage of the stepper are calculated. Is calculated, and a correction value for the deviation is calculated and input to the stepper to adjust the stepper. Using the adjusted stepper, form a resist pattern on all wafers in the same lot, measure the amount of misregistration for those products in the same way, find variations in misregistration within the lot, and control production. Used for

When used for the purpose of managing the manufacturing apparatus (stepper), a test wafer is placed on the inspection stage 2 and the position of the misalignment measurement mark formed in the wafer in the same manner as described above. The amount of displacement is measured, the signal is input to the correction value calculation means 7, and the correction value is calculated so that the running accuracy of the stage, the distortion accuracy of the lens, the alignment accuracy of the wafer, and the like are the best, and the correction value is input to the stepper. Adjust the stepper.

Conventionally, it took about 2 hours to calculate the correction value for the stepper. However, the use of the automatic misalignment management device according to the present invention can reduce the time to about 15 minutes, thereby reducing the quality of the production line. Can be managed well.

〔The invention's effect〕

As described above, in the automatic misalignment management device according to the present invention, the misalignment measurement mark formed on the wafer is converted into a luminance signal using the microscope and the photoelectric conversion unit, and the luminance signal is converted into a position signal. The position shift amount is input to the shift amount calculating means, the boundary of the position shift measurement mark is defined, and the position shift amount is calculated. Therefore, the position shift amount is calculated with high accuracy. The displacement amount is input to the correction value calculating means, and a correction value for the exposure apparatus is calculated in a short time. The correction value is fed back to the exposure apparatus, and the exposure apparatus is adjusted so that the displacement is eliminated. As a result, the quality of the production line is well controlled. In addition, since the automatic displacement control device itself is always kept in the best condition by the device performance automatic checking means, the product quality is improved and the product yield is also increased.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an automatic displacement management apparatus according to one embodiment of the present invention. FIG. 2 is a configuration diagram of a misalignment measurement mark. FIG. 3 is a diagram illustrating a luminance distribution of the misalignment measurement mark. DESCRIPTION OF SYMBOLS 1 ... Inspection stage, 2 ... Wafer, 3 ... XY stage, 4 ... Microscope, 5 ... Photoelectric conversion means, 6 ... Position shift amount calculation means, 7 ... Correction value calculation means, 8 ... … CRT, 9 …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… Preferentially possible measures for measuring displacement of the first layer 22, 2nd layer, 23 2nd layer Mark for measuring the displacement of the resist pattern for patterning.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jin Hori 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Hiroyuki Miyai 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited ( 72) Inventor Shigeru Saito 5950 Soeda, Iriki-cho, Satsuma-gun, Kagoshima Prefecture Kyushu Fujitsu Electronics Limited (56) References JP-A-62-298113

Claims (1)

(57) [Claims] An inspection stage (1) for mounting a wafer (2), an XY stage (3) for moving the inspection stage (1) in the XY directions, and an inspection stage formed on the wafer (2). A microscope (4) for enlarging the position error measurement mark, and a photoelectric conversion means (5) for converting an image of the position error measurement mark enlarged by the microscope (4) into an electric signal.
And a position shift amount calculating unit (6) that receives the luminance signal output from the photoelectric conversion unit (5) and calculates a position shift amount.
And a correction value calculating means (7) for inputting the positional deviation amount output from the positional deviation amount calculating means (6) and outputting a positional deviation correction value. An automatic misalignment management device, comprising automatic device performance checking means (9) for automatically checking the performance of the management device.