JP3569255B2 - Electron beam writing apparatus and sample position correction method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electron beam writing apparatus, and more particularly, to a method for correcting a sample holding unit.
[0002]
[Prior art]
2. Description of the Related Art As for a conventional electron beam writing apparatus, a circuit pattern formed in a lithography process for manufacturing a semiconductor or a thin-film magnetic head is highly integrated year by year, and various apparatuses have been proposed in response to a demand for miniaturization. .
[0003]
There is a need to eliminate circuit pattern distortion due to focus shift, drawing position shift, rotation, and the like due to drawing surface distortion, or to correct the amount of the shift to eliminate circuit pattern distortion. For example, in Japanese Patent Application Laid-Open No. 61-279856, a sample is provided with a mark for position detection, and the amount of deformation of the sample due to thermal expansion during writing is detected and corrected.
[0004]
[Problems to be solved by the invention]
In the above-described related art, since the sample is directly provided with the position detection mark, a drawing area on the sample is limited. Further, when the position detection mark is detected, the periphery of the mark is also drawn, which results in a lack of productivity such as a reduction in the chip size of the semiconductor and a decrease in the number of obtained chips. Deformation due to thermal expansion can be achieved by placing the sample holding device including the sample on the drawing stage and waiting until the temperature of the sample stabilizes.However, it takes several hours for the temperature to stabilize. The operation rate of the device decreases.
[0005]
An object of the present invention is to improve the drawing accuracy by detecting deformation and fluctuation of a sample or a stage and correcting a drawing position without directly providing a position detection mark on the sample in view of the above-described problems of the related art. An object of the present invention is to provide an electron beam writing apparatus and a method for correcting a sample position.
[0006]
[Means for Solving the Problems]
To achieve the above object, the present invention provides an electron gun, an electron lens for converging an electron beam, a deflector for deflecting an electron beam, a holder for mounting a sample, a stage for holding the holder, and moving the stage. In the electron beam lithography apparatus having a driving mechanism, the sample is elastically held on the holder, and a plurality of support members having position detection marks, and a relative displacement between the position detection marks is detected. And a correction means for correcting the drawing position.
[0007]
The support member is held by the holder with a spring, and the position detection mark is provided in the vicinity of a contact portion with the sample.
[0008]
In addition, a temperature detecting section for detecting the temperature of the sample is provided in the contact section, and a function of detecting a temperature change of the temperature detecting section and correcting a drawing position is provided in the correcting means.
[0009]
The method of correcting a sample position according to the present invention is provided at a point of contact with the sample, detects a distance between marks of a plurality of position detection marks capable of changing its own position, and calculates a stress deformation amount from the distance between the marks. The method is characterized in that a change in the sample position is obtained by calculation.
[0010]
Further, the method is characterized in that the temperature of the sample is measured, and the amount of thermal deformation of the sample is calculated from the temperature difference to obtain a change in the position of the sample.
[0011]
It should be noted that the correction of the writing position is performed by previously obtaining a correction amount corresponding to both the fluctuation pattern of the relative displacement and the temperature fluctuation, and correcting the correction by the correction amount of the pattern most similar to the detected change. You may.
[0012]
According to the present invention, by detecting the relative change between the position detection marks and further detecting the temperature change, the deformation and rotation of the sample are indirectly detected, and the deformation and rotation of the sample are corrected. Can be prevented from deteriorating the drawing accuracy.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of an electron beam writing apparatus according to the present invention. An electron beam 32 emitted from an electron gun 31 is shaped into a rectangle by a stop 33 and a shaping deflector 34, and is imaged at an arbitrary position on the sample (substrate) 12 by an electron lens 35 and a deflector 36, and a circuit pattern is formed. Formed on the sample 12. The sample 12 is held by a holder 11, and the holder 11 is fixed on an XY stage 14. Thus, even if the amount of electron beam deflection by the deflector 36 is about several mm, the sample 12 can be moved by the XY stage 14, and a pattern can be drawn on the entire surface of the sample.
[0014]
In this electron beam lithography apparatus, a length measuring device 101 for taking in a mark position for detecting a sample position, a temperature measuring device 102 for detecting a temperature of a sample, and inputting these detection data, the deflector 36 (and the XY stage 14). A correction arithmetic unit 103 for outputting the corrected drawing position, and a database 104 in which correction patterns of the length measurement pattern and temperature measurement pattern and the deflector 36 are stored in advance. The correction calculator 103 refers to the database 104, obtains correction data of a pattern closest to the detection data, and controls the deflector 36 (and the XY stage 39). The deflector 36 corrects the deformation of the sample position. draw.
[0015]
FIG. 2 shows the configuration of the sample holding device. The holder 11 is fixed on the stage 14. At least two or more support pins 13 are arranged on the holder 11 to support the substrate 12 on the holder 11.
[0016]
FIG. 3 shows the configuration of the support pin 13. The support pins 13 on the holder 11 have a spring element 21 for pressing the side surface of the substrate 12 and mechanically hold the substrate 12. The support pin 13 has a position detection mark 22 so that deformation and rotation of the substrate 12 can be detected. By providing a plurality of position detection marks 22, local deformation of the substrate 12 can be detected more accurately.
[0017]
It is preferable that the support pins 13 are arranged at the apexes of the substrate 12 like the support pins 13a, for example, since the amount of deformation or rotational displacement becomes largest, and a more accurate change in relative position can be detected. However, it is necessary to prevent the displacement of the support position by arranging the contact at the acute angle position of the substrate 12, and to form the acute angle corresponding contact 41 along the outer shape of the substrate 12 as shown in FIG. To prevent
[0018]
In the present embodiment, the support pins 13b, 13c, 13d, and 13e are arranged not at the vertices but at positions that can be easily supported. Further, it is not necessary that all of the support pins 13 be movable parts having spring elements, and a similar effect can be obtained even if the opposite side where the movable support pins are arranged is a fixed support pin.
[0019]
Next, the configuration of the support pins will be described. The support pin 13 has a spring element 21 disposed on the holder 11 and supports the substrate 12 via the contact 23. By arranging the position detection mark 22 on the support pin 13 on the contact 23 disposed on the substrate 12 side of the spring element 21, the influence of the extension of the spring element 21 can be eliminated.
[0020]
In vacuum, heat conduction is considered to be conduction through contact and radiation due to radiation.However, there is no high temperature part where radiation effects occur in the drawing part of the electron beam lithography system, and everything is considered to be heat conduction. Can be Therefore, by forming the contact 23 in contact with the substrate 12 with a temperature measuring means such as a thermocouple, or by incorporating the temperature measuring means 24 in the contact 23 as shown in FIG. Temperature measurement becomes possible. A thermocouple or the like is used as the temperature measuring unit 24.
[0021]
Next, a correction method will be described. FIG. 5 is a flowchart showing a procedure of a sample position correcting method according to one embodiment. First, the correction computer 103 sets one of the position detection marks 22 as the origin, detects the position of the origin and the relative position of the remaining position detection marks 22 from the origin (501), and determines whether or not the distance between the marks has changed. A determination is made (502). If there is no change in the mark-to-mark distance, the substrate 12 has not been deformed, and the drawing is performed without correction (503).
[0022]
If the distance between the marks has changed, it is next determined whether or not there is a temperature change (504). The temperature is measured when the mark is detected. If a temperature change has occurred, the substrate 12 has undergone thermal deformation, so the amount of thermal expansion is calculated from the temperature difference based on the specific thermal expansion coefficient of the substrate 12 to determine the amount of thermal deformation correction (505). If there is no temperature change, step 505 is skipped.
[0023]
Next, it is determined whether or not the sample is shifted due to the stage movement (506). When the shift has occurred, since the parallel movement and rotation due to the slip of the sample have occurred, the mark 15 on the stage of FIG. 2 is used as the position of the origin, and the position is determined based on the positional relationship with the individual position detection marks 22. Then, the slip amount is calculated (507).
[0024]
Next, a correction amount for correcting a change in the distance between the individual position detection marks 22 is obtained (508). This deformation is a stress deformation due to an external force of a support pin or the like. By measuring a change in the distance between the individual position detection marks 22, it is possible to know what kind of stress is acting. Since the correction amount can be calculated, the image is corrected and drawn (509).
[0025]
It should be noted that the correction amount can be obtained at any time after the measurement of the distance between marks by calculation such as simulation. However, the processing speed of the electron beam lithography apparatus is high, and it is difficult to obtain the correction amount during the lithography by the above-described method. Therefore, the correction amount is obtained from the previously measured change in the distance, and the correction amount database 104 is constructed, whereby the correction amount can be immediately obtained from the measured distance change. It should be noted that the correction amount database 104 can be similarly constructed for the temperature change.
[0026]
By the above-described method, the respective correction amounts are obtained, and these are combined at the time of drawing to correct them, thereby enabling accurate drawing without being affected by deformation.
[0027]
The reference (origin) for correcting the deformation and rotation of the sample with the position detection mark 22 is to use one of the position detection marks 22 as the origin and detect the relative displacement of the remaining position detection marks 22 from the origin. To obtain the correction amount. However, even if a reference position detection mark is arranged on the holder 11 or a position detection mark 15 is provided on the stage 14, the same effect on the correction of the deformation of the substrate 12 can be obtained.
[0028]
The more the number of times the position detection mark 22 is detected, the more accurate the change can be measured. However, considering the temperature change of the holder 11 due to the heat transmitted from the stage and the time constant of the deformation of the substrate 12, it is preferable to perform the measurement for each drawing pattern. . This makes it possible to reduce the number of detections and increase the production efficiency.
[0029]
【The invention's effect】
According to the present invention, since the deformation of the sample and the holder can be detected and the drawing position can be corrected, there is an effect of obtaining highly accurate drawing.
[0030]
Further, there is an effect that correction by temperature deformation can be performed by passing the temperature measuring means to the sample supporting portion.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment showing an electron beam drawing apparatus of the present invention.
FIG. 2 is a plan view of the holding device.
FIG. 3 is a sectional view of a sample holding portion.
FIG. 4 is a plan view of a sample holding portion.
FIG. 5 is a flowchart illustrating a correction method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Holder, 12 ... Substrate, 13 ... Support pin, 14 ... Stage, 21 ... Spring element, 22 ... Position detection mark, 23 ... Contact, 24 ... Temperature measuring means, 31 ... Electron gun, 32 ... Electron beam, 33 ... stop, 34 ... molded polarizer, 35 ... electron lens, 36 ... deflector, 41 ... acute angle compatible contactor.

Claims (2)

Electron beam drawing including an electron gun, an electron lens for converging an electron beam, a deflector for deflecting an electron beam, a holder for mounting a sample, a stage for holding the holder, and a driving mechanism for moving the stage. In the device,
A plurality of support members elastically supporting the sample in the holder, and having a position detection mark in the vicinity of the contact portion with the sample, a temperature detection unit that detects the temperature of the sample in the contact portion, An electron beam lithography apparatus comprising: a correction unit that detects a relative displacement between the position detection marks to correct a writing position and detects a temperature change of the temperature detection unit to correct the writing position. . When deflecting an electron beam of an electron beam lithography apparatus to draw on a sample, a method of correcting a writing position in accordance with a change in the position of the sample includes:
A distance between marks of a plurality of position detection marks provided at a contact point with the sample and capable of changing its own position is detected, and a stress deformation amount is calculated from the distance between the marks to obtain a change in the sample position. Along with the sample position, wherein a change in the sample position is obtained by detecting a temperature change of a temperature detecting unit for detecting the temperature of the sample provided at the contact point, calculating the amount of thermal deformation of the sample, and calculating the change in the sample position. Correction method.

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