JP5635240B2 - Calibration block and charged particle beam drawing apparatus - Google Patents

Description

The present invention relates to a process for producing a calibration block that is provided on the stage for the calibration of the height measuring device by entering reflect light on the placing surface of the sample on the stage to measure the height of the sample, the production The present invention relates to a calibration block manufactured by the method and a charged particle beam drawing apparatus using the calibration block .

  The charged particle beam drawing apparatus includes a stage on which a sample is placed and beam irradiation means, and draws a predetermined pattern by irradiating the sample placed on the stage with a charged particle beam by the beam irradiation means. It is configured. Here, when the height of the sample changes, the irradiation position on the sample of the charged particle beam deflected by the deflector provided in the beam irradiation means changes. For this reason, a height measuring device is provided to measure the height of the sample by reflecting the light beam on the surface of the sample placed on the stage, and the charged particle beam is deflected according to the height measured by the height measuring device. The angle is corrected.

  Conventionally, a calibration block for calibration of the height measuring instrument has been provided on the stage, and the light from the height measuring instrument is incident on and reflected from the reference reflecting surface on the upper surface of the calibration block. There is also known one that calibrates the height measuring device based on the relationship between the height and the height of the reference reflecting surface (for example, see Patent Document 1). This calibration block is made of metal, and the upper surface thereof is machined so that the surface roughness Ra is about 0.01 to form a reference reflecting surface.

  By the way, during drawing, part of the magnetic field of the deflector and objective lens provided in the beam irradiation means leaks onto the stage, and the calibration block moves in the leakage magnetic field as the stage moves, resulting in a metal calibration block. Eddy currents may be generated. Then, an error occurs in the irradiation position of the charged particle beam due to the influence of the magnetic field due to the eddy current, and the drawing accuracy is lowered.

JP-A-6-3115

In view of the above points, the present invention provides a method for manufacturing a calibration block capable of suppressing the generation of eddy currents and ensuring a high degree of smoothness of the reference reflecting surface, a calibration block manufactured by this manufacturing method, and the calibration An object of the present invention is to provide a charged particle beam drawing apparatus using a block .

In order to solve the above-described problem, the first aspect of the present invention is for calibration of a height measuring instrument that measures the height of a sample by causing light rays to enter and reflect the surface of the sample placed on the stage. , is al provided on the stage, a calibration block having a reference reflection surface for reflecting light rays from a height measuring device on the upper surface, the block body made of non-conductive material, is laminated on the upper surface of the block body , non-magnetic material or magnetization curve is characterized and the metal of the first coating with a reference reflective surface of the surface roughness 0.01-0.03 made of a magnetic material having no hysteresis, the Rukoto comprises a.

In a first aspect of the present invention, Rukoto comprises a metal of the second coating on the bottom surface of the block body is desired.

The second aspect of the present invention includes a stage on which a sample is placed, and beam irradiation means, and the sample placed on the stage is irradiated with a charged particle beam by the beam irradiation means to form a predetermined pattern. A charged particle beam drawing apparatus for drawing, an optical height measuring device that measures the height of a sample by making light rays incident on the surface of the sample placed on the stage, and calibration of the height measuring device Therefore, a block body provided on the stage and made of a non-conductive material and laminated on the top surface of the block body and having a surface roughness of 0. And a calibration block having a metal first coating of 01 to 0.03.

In the second aspect of the present invention, Rukoto comprises a metal of the second coating on the bottom surface of the block body is desired.

The third aspect of the present invention is provided on the stage for the calibration of a height measuring instrument that measures the height of the sample by causing light rays to enter and reflect the surface of the sample placed on the stage. A method of manufacturing a calibration block having a reference reflecting surface for reflecting light from a height measuring device on the upper surface,
On the upper surface of the block body made of a non-conductive material, a metal first film made of a non-magnetic material or a magnetic material having a magnetization curve having no hysteresis is laminated, and the surface of the first film is machined It is characterized by finishing to a reference reflecting surface .

  According to the present invention, even if the calibration block moves in a leakage magnetic field, the block body is formed of a non-conductive material, so that generation of eddy currents is suppressed and drawing accuracy can be ensured. Further, by machining the metal coating, it is possible to ensure a high degree of smoothness of the reference reflecting surface, to prevent variations in the measurement height by the height measuring instrument, and to prevent a calibration error of the height measuring instrument.

The conceptual diagram which shows the structure of the electron beam drawing apparatus which is the drawing apparatus of embodiment of this invention. Explanatory drawing which shows the manufacturing method of the calibration block of embodiment of this invention. Explanatory drawing which shows the manufacturing method of the calibration block of other embodiment of this invention.

  FIG. 1 shows an electron beam drawing apparatus which is an example of a charged particle beam drawing apparatus of the present invention. The electron beam drawing apparatus includes a drawing chamber 1 and an electron column 2 that is a beam irradiation means standing on the ceiling of the drawing chamber 1. The drawing chamber 1 is provided with a stage 3 that is movable in the X and Y directions orthogonal to each other, and a sample W is placed on the stage 3. The sample W is, for example, a mask in which a light shielding film such as a chromium film and a resist film are stacked on a glass substrate.

  The electron column 2 includes an electron gun 21, various lenses 22 including an objective lens 22-1, a blanking deflector 23, a beam shaping deflector 24, a beam scanning sub deflector 25, and a beam scanning main deflection. And a blanking aperture 27 and a beam shaping aperture 28. The beam shaping deflector 24 and the beam shaping aperture 28 serve to variably control the beam shape.

The electron column 2 is controlled by the irradiation controller 4, and the stage 3 is controlled by the stage controller 5. The irradiation control unit 4 and the stage control unit 5 are comprehensively controlled by the overall control unit 6. The overall control unit 6, the first memory ₇₁ and a ₂ second memory 7 is connected. The first memory ₇₁ pattern data is stored. The overall control unit 6, the shape of the graphic to be drawn based on the pattern data, to create the drawing data defining the position, and stores it in ₂ second memory 7.

  Further, the electron beam drawing apparatus includes a stage position measuring device 8 that measures the position of the stage 3 in the X direction and the Y direction, and a height measuring device 9 that measures the height of the sample W placed on the stage 3. I have. The stage position measuring device 8 is composed of a laser length meter that measures the position of the stage 3 by incident / reflected laser light on a stage mirror 3 a fixed to the stage 3.

  The height measuring device 9 includes a light projecting unit 9a that converges and irradiates laser light on the surface of the sample W obliquely from above, and a light receiving unit 9b that receives the reflected light from the sample W and detects the position of the reflected light. The height calculation unit 9c calculates the height of the sample W from the position of the reflected light. The height data of the sample W measured by the height measuring device 9 is input to the overall control unit 6. Then, the overall control unit 6 calculates the deflection angle and focus range of the electron beam necessary to maintain the drawing accuracy according to the deviation amount of the height of the sample W from the normal height, and corrects the drawing data. To do.

  When drawing a pattern on the sample W, an operation command is issued from the overall control unit 6 to the stage control unit 5, and the stage 3 is moved. Further, the irradiation control unit 4 controls the shaping of the electron beam in the electron column 2 while confirming the position of the stage 3 measured by the stage position measuring device 8 based on the drawing data input from the overall control unit 6. Deflection control is performed to irradiate a desired position of the sample W with an electron beam.

  Here, a calibration block 10 for calibrating the height measuring device 9 is provided on the stage 3. As shown in FIG. 2B, the calibration block 10 has a reference reflecting surface 101 that reflects the laser light from the light projecting portion 9a of the height measuring device 9 on the upper surface. The reference reflecting surface 101 has a plurality of steps in a staircase pattern. Then, the stage 3 is moved and adjusted so that the laser light from the light projecting unit 9a of the height measuring device 9 enters and reflects each stage of the reference reflecting surface 101, and based on the position of reflected light detected by the light receiving unit 9b. The height measuring unit 9c is compared with the height of each step of the reference reflecting surface 101, and the height measuring device 9 is calibrated so that the measurement height error is corrected.

By the way, during drawing, a part of the magnetic field generated by the main deflector 26 and the objective lens 22-1 provided in the lower part of the electron lens barrel 2 leaks onto the stage 3, and is calibrated in the leaked magnetic field as the stage 3 moves. The block 10 may move. If the calibration block 10 is made of metal, an eddy current is generated in the calibration block 10, and an error occurs in the irradiation position of the electron beam due to the influence of the magnetic field due to the eddy current, resulting in a reduction in drawing accuracy.
Therefore, conventionally, it has been studied to form the block main body of the calibration block with ceramics, which is a non-conductive material, and to cover with a metal. Such a calibration block is formed, for example, by smoothing the upper surface of the block body by machining, and then laminating a thin film serving as a reference reflecting surface made of gold plating with a thickness of about 0.5 μm on the upper surface of the block body. be able to. However, even if the upper surface of the ceramic block body is machined smoothly, the surface roughness Ra is only about 0.05, and the surface roughness of the thin film laminated thereon is also about the same. As a result, the height measured by the height measuring instrument varies, and the calibration error of the height measuring instrument tends to occur.

  Therefore, in the present embodiment, the calibration block 10 is manufactured as follows. That is, the block main body 102 of the calibration block 10 is formed of a non-conductive material, and a metal film 103 is laminated on the upper surface of the block main body 102 by plating or spraying as shown in FIG. Thereafter, as shown in FIG. 2B, the surface of the coating 103 is finished to a reference reflecting surface 101 by machining. A flange portion 102a is integrally formed at the lower portion of the block main body 102, and the calibration block 10 is bolted to the stage 3 in an attachment hole 102b formed in the flange portion 102a.

  Examples of the nonconductive material forming the block body 102 include ceramics such as silicon carbide, alumina, zirconia, quartz, glass, Si, and the like. Further, it is desirable that the material forming the block body 102 is a non-magnetic material so that the block body 102 is not magnetized in the leakage magnetic field. Although most ceramics are non-magnetic materials, strictly speaking, they are magnetic materials that are slightly magnetized. Here, although the strength of the leakage magnetic field reaching the calibration block 10 changes as the stage 3 moves, the strength of this magnetic field can be examined in advance. Even if the material forming the block body 102 is a magnetic body, if the magnetization curve is a magnetic body having no hysteresis, the magnetization strength of the block body 102 is uniquely determined according to the strength of the magnetic field examined in advance. The influence on the drawing accuracy due to the magnetization of the block main body 102 can be corrected. Therefore, the forming material of the block body 102 may be a magnetic material whose magnetization curve has no hysteresis.

  Examples of the metal that forms the coating 103 include nickel, titanium, gold, and the like. Among them, nickel, which has a relatively large specific resistance of about 6.9 μΩ · cm, is inexpensive, and is easy to machine, is preferable. Further, if the film thickness of the film 103 before machining is less than 10 μm, pinholes are generated or the influence of the surface roughness of the block body 102 appears on the surface of the film 103, and the surface of the film 103 is machined smoothly. There is a possibility that the block main body 102 is exposed during the processing. Therefore, the film thickness of the coating 103 before machining is desirably 10 μm or more. Moreover, if the film thickness is 100 μm or less, the electrical resistance value of the film 103 becomes high, and the generation of eddy currents in the film 103 can be suppressed. When the film thickness exceeds 100 μm, since the film thickness is reduced to such an extent that the generation of eddy current is suppressed, the machining allowance by machining increases unnecessarily. It is desirable that the thickness be 100 μm or less.

  The surface of the coating 103, that is, the reference reflecting surface 101 is finished by machining so that the surface roughness Ra is about 0.01 to 0.03. Here, examples of the machining include cutting and grinding. However, since the edge of the reference reflective surface 101 is likely to sag in the grinding, the surface of the coating 103 is removed by cutting. It is preferable to finish.

  If the calibration block 10 manufactured as described above is used, even if the calibration block 10 moves in the leakage magnetic field, the block body 102 is formed of a non-conductive material, so that the generation of eddy currents is suppressed and the drawing accuracy is improved. It can be secured. Further, by machining the surface of the metal coating 103, a high degree of smoothness of the reference reflecting surface 101 can be secured, and the height measured by the height measuring device 9 does not vary, and the height measuring device 9 Calibration errors can be prevented.

  By the way, when machining the coating 103, it is necessary not only to make the surface smooth, but also to adjust the height of each step of the reference reflecting surface 101 to a predetermined specified height. It is not easy to match the height while securing the height. An embodiment of a method for manufacturing the calibration block 10 that facilitates height adjustment will be described with reference to FIG.

  In this embodiment, as shown in FIG. 3A, the block body 102 is made of a non-conductive material, and a metal coating 103 is laminated on the upper surface of the block body 102 to a thickness of about 10 to 100 μm. This point is the same as in the above embodiment, but a second metal film 104 having a predetermined film thickness (for example, 100 μm) is further laminated on the lower surface of the block main body 102. Then, as shown in FIG. 3B, the surface of the coating 103 is machined so that the surface roughness Ra is about 0.01 to 0.03 to finish the reference reflective surface 101. Thereafter, the height of the reference reflecting surface 101 is measured, and the second coating 104 is machined as shown in FIG. 3C so that this height becomes a specified height. According to this, it is only necessary to ensure the smoothness of the surface when machining the coating 103, and the height of the reference reflecting surface 101 can be easily adjusted by machining the second coating 104.

  During drawing, a part of the electron beam irradiated on the sample W is reflected, and the reflected electrons may hit not only the reference reflecting surface 101 of the calibration block 10 but also the peripheral side surface of the block main body 102 or the like. Then, the block body 102 made of a non-conductive material is charged up with electric charges, which adversely affects the drawing accuracy. In order to prevent such charge-up, a conductive material, for example, a gold thin film (with a film thickness of about 0.5 μm) is formed on the entire surface of the block body 102 before the coatings 103 and 104 are formed. Also good.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to this. For example, the reference reflecting surface 101 of the calibration block 10 of the above embodiment has a plurality of steps in a staircase shape, but forms a reference reflecting surface that connects the lowermost step and the uppermost step with an inclined surface. Also good. In the above-described embodiment, the present invention is applied to an electron beam lithography apparatus that irradiates an electron beam. However, the present invention can be similarly applied to a lithography apparatus that irradiates other charged particle beams such as an ion beam. .

W ... Sample 2 ... Electronic column (beam irradiation means)
DESCRIPTION OF SYMBOLS 3 ... Stage 9 ... Height measuring instrument 10 ... Calibration block 101 ... Reference | standard reflection surface 102 ... Block main body 103 ... Coating | coated 104 ... 2nd coating | coated

Claims (4)

For calibration of a height measuring instrument that measures the height of a sample by making the light incident on and reflected from the surface of the sample placed on the stage, the light from the height measuring instrument is placed on the top surface. A calibration block having a reflective reference reflective surface,
A non-magnetic body or a magnetic body whose magnetization curve has no hysteresis and a block body made of non-conductive ceramics;
A calibration block, comprising: a metal first film laminated on an upper surface of the block body and having a reference reflection surface having a surface roughness of 0.01 to 0.03.   The calibration block according to claim 1, further comprising a second metal film on a lower surface of the block main body. A charged particle beam drawing apparatus comprising a stage for placing a sample and a beam irradiating means, and irradiating the sample placed on the stage with a charged particle beam by the beam irradiating means to draw a predetermined pattern,
An optical height measuring device that measures the height of the sample by causing light rays to enter and reflect on the surface of the sample placed on the stage;
For the calibration of the height measuring device, a non-magnetic material or a magnetic body having a magnetization curve having no hysteresis and a non-conductive ceramic block body provided on the stage, and an upper surface of the block main body A charged particle beam drawing apparatus comprising: a calibration block that is laminated and has a first metal film having a reference reflective surface with a surface roughness of 0.01 to 0.03.   The charged particle beam drawing apparatus according to claim 3, further comprising a second metal film on a lower surface of the block main body.

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