JP2010074059A - Ground pin, ground plate, charged particle beam-drawing system, and charged particle beam-drawing method - Google Patents

Abstract

Provided are a ground pin, a ground plate, a charged particle drawing apparatus, and a charged particle drawing method capable of optimizing the material and shape of an earth pin used for grounding a mask in charged particle beam drawing and obtaining high drawing accuracy.
An earth pin according to the present invention is an earth pin for grounding a specimen to be used for charged particle beam drawing, exhibits paramagnetism, and a contact portion that contacts the specimen has a curved surface.
[Selection] Figure 2

Description

  The present invention relates to an earth pin, an earth plate, a charged particle beam drawing apparatus, and a charged particle beam drawing method used for charged particle beam drawing.

  In recent years, with higher integration of semiconductor devices, there is a demand for miniaturization of mask patterns for forming circuit patterns. A charged particle beam drawing apparatus having excellent resolution is used to form a fine mask pattern.

  With such a charged particle beam drawing apparatus, a charged particle beam such as an electron beam is irradiated onto a sample in which, for example, a Cr film (light-shielding film) and a resist film are sequentially formed on a quartz glass substrate, and pattern writing is performed. The film is exposed to a predetermined pattern. Then, a light shielding pattern (mask pattern) of Cr is formed by development and etching.

  When the mask pattern is formed in this way, the charged particle beam trajectory is bent or the beam blur occurs due to the charge-up of the resist film during pattern drawing, and the mask pattern drawing accuracy deteriorates. Problem occurs. Therefore, it is necessary to bring the conductive member into contact with the Cr film and ground it.

  Therefore, as a conductive member, a member having a high hardness such as tungsten carbide processed into a needle shape or a blade shape, conductive diamond, or ceramic coated with a conductive coating is used because of the necessity of penetrating the resist film. (See, for example, Patent Document 1).

However, there is a problem that the glass substrate is damaged by the contact and causes generation of particles, or wear and chipping of the contact portion cause particles to be generated and contact failure, thereby reducing the drawing accuracy.
Japanese Patent Laying-Open No. 2005-127719 (paragraphs [0014] and [0015])

  As described above, a high-hardness conductive member processed into a needle shape or a blade shape is used as a member used for grounding the mask, but the drawing accuracy is reduced due to generation of particles, poor contact, and the like. There is a problem.

  On the other hand, the magnetic field applied in the electron lens for controlling the charged particle beam to a desired position is increasing with the increase in accuracy of the charged particle beam drawing apparatus. The magnetism of the member used for grounding the mask greatly affects the drawing accuracy.

  Accordingly, the present invention provides an earth pin, an earth plate, a charged particle drawing apparatus, and a charged particle drawing method capable of optimizing the material and shape of an earth pin used for grounding a mask in charged particle beam drawing and obtaining high drawing accuracy. The purpose is to provide.

  The ground pin according to the present invention is a ground pin for grounding a sample to be used for charged particle beam drawing, and exhibits paramagnetism, and a contact portion in contact with the sample has a curved surface.

  Moreover, it is preferable that at least the tip of the ground pin of the present invention is made of conductive zirconia or conductive diamond.

  An earth plate according to the present invention is an earth plate used for grounding a specimen to be subjected to charged particle beam writing, and exhibits a paramagnetism, a ground pin having a curved surface at a contact portion in contact with the specimen, and the earth pin as a specimen. And a plate exhibiting paramagnetism for fixing to the plate.

  The charged particle beam drawing apparatus according to the present invention includes a first chamber in which a ground pin that is paramagnetic and has a curved surface in contact with the sample is disposed at a predetermined position on the sample, and a ground terminal that grounds the ground pin. And a second chamber for irradiating the sample with a charged particle beam.

  In the charged particle beam writing method according to the present invention, an earth pin that exhibits paramagnetism and has a curved surface in contact with the sample is disposed at a predetermined position on the sample, and the sample and the earth pin are electrically connected, Drawing is performed by grounding with an earth spin and irradiating with a charged particle beam.

  According to the present invention, it is possible to provide an earth pin, an earth plate, a charged particle beam drawing apparatus, and a charged particle drawing method capable of obtaining high drawing accuracy.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1A is a side view showing a configuration of an earth plate used in an electron beam drawing apparatus which is a charged particle beam drawing apparatus of the present embodiment, and FIG. 1B is a bottom view thereof. As shown in the figure, the earth plate 11 is arranged such that a paramagnetic earth pin 12 made of titanium and conductive diamond is fitted into a hole provided in a paramagnetic plate 13 made of conductive zirconia. It is configured. The earth pin 12 is made of, for example, Ti and conductive diamond. For example, as shown in a partially enlarged view in FIG. 2, it has a rod shape of, for example, φ0.6 mm, is thinned toward the tip, the support portion 12a is made of titanium, and the tip portion 12b is made of conductive diamond. The contact portion 12c has a curved surface with, for example, φ40 μm and a curvature radius R = 20 μm.

  Using the earth plate 11 on which such earth pins 12 are arranged, drawing is performed on the sample as follows.

  First, as shown in FIG. 3, the earth plate 11 is fixed to, for example, three places of a frame-like conductive frame having an opening at the center by screwing or the like to protect the edge of the sample during drawing. The mask cover 14 is configured. At this time, the ground pin 12 is disposed so as to protrude into the opening of the mask cover 14. The mask cover 14 to which the earth plate 11 is attached in this way is attached to the sample 10 (broken line) used for drawing in the electron beam drawing apparatus.

  FIG. 4 shows a schematic configuration of the electron beam drawing apparatus according to the present embodiment. The electron beam drawing apparatus 20 of the present embodiment shown in FIG. 4 includes a load lock chamber 21 for loading the sample 10 and the like and switching to a vacuum state, and a robot arm 22 for transporting the loaded sample 10 and the like. A transfer chamber 23, an alignment chamber 24 for aligning the sample 10, a stage 25, a mask cover storage chamber 26 for attaching the mask cover 14 to a predetermined position on the sample 10, and a sample 10 And a drawing chamber 27 for drawing.

  Then, the sample 10 in which the Cr film and the resist film are sequentially laminated on the glass substrate is carried from the load lock chamber 21 and is carried by the robot arm 22 to the alignment chamber 24 via the carrying chamber 23. In the alignment chamber 24, edge scanning using a CCD camera (not shown) or the like is used to detect and correct the positional deviation or rotational deviation of the sample 10.

  The sample 10 in which the positional deviation and the rotational deviation are corrected is conveyed by the robot arm 22 to the mask cover storage chamber 26 via the conveyance chamber 23. After the transported sample 10 is placed on the stage 25, a mask cover 14 is attached on the sample 10. At this time, the tip of the earth pin 12 penetrates the resist film and contacts the Cr film at the contact portion 12c.

  Next, a voltage is applied between different earth plates 11 from an external power source (not shown) to check whether the earth pin 12 and the Cr film are in conduction. If continuity is not confirmed, the mask cover 14 is once removed from the sample 10 and attached again. The sample 10 / mask cover 14 that has been confirmed to be conductive is transferred to the drawing chamber 27 by the robot arm 22 via the transfer chamber 23.

  The sample 10 / mask cover 14 conveyed to the drawing chamber 27 is placed on a stage (not shown) and grounded via the earth plate 11 and a ground terminal (not shown). A desired pattern is drawn by irradiating a desired position of the sample 10 with an electron beam emitted from an electron gun (not shown) and shaped into a desired shape.

  The sample 10 on which the pattern has been drawn is unloaded from the drawing chamber 27 while being attached to the mask cover 14, and is carried into the mask cover storage chamber 26 via the transfer chamber 23 by the robot arm 22. Then, after removing the mask cover 14 on the sample 10, the sample 10, if necessary, the mask cover 14 is unloaded from the mask cover storage chamber 26, and is transferred from the electron beam drawing apparatus via the transfer chamber 23 and the load lock chamber 21. It is carried out.

  In this way, when drawing on the sample, the ground is grounded by the earth plate, thereby preventing the charge-up. And since the contact part of an earth pin has a curved surface, even if it contacts a sample repeatedly, it does not penetrate the Cr film and reaches the glass substrate, and generation of particles due to damage to the glass substrate is suppressed. In addition, since wear and chipping of the ground pin are suppressed, poor contact can be suppressed, high drawing accuracy can be obtained, and maintenance time can be shortened by reducing the replacement frequency.

  In addition, since the earth plate is made of a non-magnetic material, in order to improve the drawing accuracy, even when a high magnetic field of, for example, about 2500 G is applied, the influence of the magnetic field on the drawing accuracy can be suppressed.

  In this embodiment, the contact portion of the ground pin is formed to be a curved surface having a radius of curvature of R = 20 μm at φ40 μm, but is formed to have a radius of curvature of R = 15-25 μm at φ30-50 μm. Is preferred. If the curved surface is larger than φ50 μm or the curvature radius R is larger than 25 μm, it becomes difficult to penetrate the resist film. On the other hand, if the diameter is less than 30 μm or the radius of curvature R is less than 15 μm, the glass substrate may be damaged or chipped. More preferably, it is 35-45 micrometers.

In addition, even if it is a paramagnetic material in an ingot state, the earth pin needs to be a paramagnetic material when processed into a pin shape of about φ0.6 mm, for example. This is based on the knowledge that when WC (tungsten carbide), which is a paramagnetic material, is processed into a pin shape and used as an earth pin in a strong magnetic field, it becomes a ferromagnetic material and is affected by the magnetic field. Examples of such a pin-shaped material exhibiting paramagnetism include conductive diamond, conductive zirconia, and conductive ceramics such as Altic (Al ₂ O ₃ / TiC).

As the conductive diamond, diamond doped with, for example, B (boron) is used. The dopant is not particularly limited, and P (phosphorus), Si ₃ N ₄ (silicon nitride), or the like can also be used.

As the conductive zirconia, for example, zirconia doped with WC, NbC (niobium carbide), Y ₂ O ₃ (yttria oxide), CaO (calcium oxide), TiO ₂ (titanium dioxide), or the like is used.

  For other metals, it is considered that a paramagnetic material such as Ti can be used. However, since the durability is not sufficient for use in a contact portion in contact with a Cr film, the tip is combined with conductive diamond. It can be used for other parts.

  In this embodiment, conductive zirconia is used as the plate, but a paramagnetic material similar to the earth pin can be used. Since it is plate-shaped and does not require durability as much as the ground pin, it is possible to use a paramagnetic material such as Ti.

  Further, although the earth plate is fixed at three positions on the mask cover, a plurality of earth plates may be used in order to confirm the continuity and to securely ground the Cr film.

  Further, the electron beam drawing apparatus has been described, but the present invention can be applied to a drawing apparatus using a charged particle beam including an ion beam.

  In addition, this invention is not limited to embodiment mentioned above. Various other modifications can be made without departing from the scope of the invention.

The side view which shows the structure of the earth plate which concerns on embodiment of this invention. The bottom view which shows the structure of the earth plate which concerns on embodiment of this invention. The elements on larger scale of the earth plate which concerns on embodiment of this invention. The top view which shows the mask cover which concerns on embodiment of this invention. The figure which shows the structure of the electron beam drawing apparatus which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Sample 11 ... Earth plate 12 ... Earth pin 13 ... Plate 14 ... Mask cover 20 ... Electron beam drawing apparatus 21 ... Load lock chamber 22 ... Robot arm 23 ... Transfer chamber 24 ... Alignment chamber 25 ... Stage 26 ... Mask cover storage chamber 27 ... Drawing chamber

Claims (5)

  An earth pin for grounding a specimen to be used for charged particle beam drawing, wherein the earth pin exhibits paramagnetism, and a contact portion in contact with the specimen has a curved surface.   The ground pin according to claim 1, wherein at least a tip of the ground pin is made of conductive zirconia or conductive diamond. An earth plate used for grounding a sample to be used for charged particle beam writing,
An earth pin that exhibits paramagnetism and has a curved surface in contact with the sample;
A plate showing paramagnetism for fixing the ground pin to the sample;
An earth plate comprising: A first chamber in which a ground pin is disposed at a predetermined position on the sample, and shows a paramagnet, and a contact portion that contacts the sample has a curved surface;
A charged particle beam drawing apparatus, comprising: a second chamber that includes a ground terminal that grounds the ground pin, and irradiates the sample with a charged particle beam. Place a ground pin that shows paramagnetism at a predetermined position on the sample and has a curved surface in contact with the sample, and after conducting the sample and the ground pin,
A charged particle beam drawing method, wherein drawing is performed by grounding the sample with the earth pin and irradiating a charged particle beam.

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