JP2012203163A - Foreign matter removing method and foreign matter removing device for photomask - Google Patents

Abstract

The present invention provides a foreign matter removing method and a foreign matter removing apparatus for a photomask capable of accurately removing foreign matter that has entered a fine concave portion of a pattern.
The cantilever 12 is displaced up and down while controlling the triaxial fine movement mechanism 21 so that the displacement amount of the cantilever 12 is constant, and the surface of the substrate 01 and the foreign matter 02 are scanned by scanning the surface of the substrate 01. Get three-dimensional information. The approach position of the probe 11 and the approach amount in the depth direction are determined based on the three-dimensional information of the surface of the substrate 01 and the foreign object 02, and then the probe 11 is approached to the foreign object 02 with the determined values. At the moment when the probe 11 (the thin tube 14) comes into contact with the foreign material 02, the foreign material 02 is adsorbed by the thin tube 14. With the foreign matter 02 adsorbed on the thin tube 14, the probe 11 is pulled up together with the cantilever 12 to remove the foreign matter 02 that has entered the recess of the substrate 01.
[Selection] Figure 1

Description

  The present invention relates to a foreign matter removing method and a foreign matter removing apparatus for removing a foreign matter adhering to a photomask, in particular, a foreign matter entering a fine concave portion.

  In recent years, in semiconductor processing, in particular, processing of large-scale integrated circuits, circuit patterns have been miniaturized with higher integration. As a result, in the production of photomasks, a technique for forming a finer and higher-accuracy mask pattern is required with the miniaturization. Further, when the mask pattern is miniaturized, even a small foreign matter affects the wafer transfer.

  If some foreign matter enters and adheres to the recesses (grooves) of the fine mask pattern, and the adhesion is strong, it is difficult to wash away the foreign matter only by the cleaning process, and the foreign matter is once peeled off from the mask. It is necessary to perform the cleaning process on the weakened adhesive force.

  In this case, it is necessary to move the foreign matter from the concave portion (releasing the contact state) by applying a certain amount of force to the foreign matter that has entered the concave portion using a probe. For example, using AFM (Atomic Force Microscope) technology A method of applying a load to a foreign object with a probe is known.

  As the probe tip material, silicon, diamond, or the like is generally used, and it is possible to cope with a pattern size of a half pitch 45 nm generation. However, as the miniaturization of patterns progresses, there is a limit to narrowing the probe from these tip materials.

  Therefore, Patent Document 1 discloses a method for removing foreign matter using carbon nanotubes as a leading material. Since the carbon nanotube can be controlled in manufacturing a structure having a diameter of several nm to 100 nm, it can be moved by applying a load to the foreign matter that has entered the concave portion of the pattern having a half pitch of 45 nm or less.

  Patent Document 2 discloses a foreign matter removing apparatus including a blow device that blows compressed air to blow off foreign matter and an exhaust fan that discharges the blown foreign matter to the outside through an exhaust port.

JP 2010-054773 A JP 2007-316551 A

  However, the technique of applying a load to the foreign matter that has entered the concave portion of the pattern using the carbon nanotubes only moves the foreign matter, and does not remove the foreign matter from the concave portion. There has been a problem that it cannot always be removed by a cleaning process.

  Similarly, even when compressed air is blown, there has been a problem that the foreign matter that has entered the fine recesses is not always blown away.

  In this way, as the pattern miniaturization and high accuracy in recent photomasks progress, even a minute foreign matter will affect the wafer transfer. Even if it has entered into the concave portion, it is desired to remove it with high accuracy.

  In view of the above circumstances, an object of the present invention is to provide a foreign matter removing method and a foreign matter removing apparatus capable of accurately removing foreign matter that has entered a fine concave portion of a pattern.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a photomask foreign matter removal method for removing foreign matter attached to a photomask, and acquires the three-dimensional information of the surface of the photomask and the foreign matter. The step of identifying the position of the foreign matter based on the three-dimensional information, and moving the probe tip based on the position of the identified foreign matter to suck the foreign matter with the probe tip, and then A step of removing the foreign matter from the photomask by separating from the photomask; and a step of releasing the suction and removing the foreign matter sucked by the probe tip from the probe tip. .

  According to a second aspect of the present invention, in the photomask foreign matter removing method according to the first aspect, the probe tip is formed of a hollow thin tube.

  According to a third aspect of the present invention, in the photomask foreign matter removing method according to the second aspect, the material of the narrow tube is a carbon nanotube, and the diameter thereof is several nm to 100 nm.

  According to a fourth aspect of the present invention, in the foreign matter removing method for a photomask according to any one of the first to third aspects, in the step of removing the foreign matter sucked by the probe tip from the probe tip, It is characterized by blowing gas toward a foreign object.

  The invention according to claim 5 is the photomask foreign matter removal method according to any one of claims 2 to 4, wherein the probe has a pedestal that supports the narrow tube, and the pedestal has at least a diameter or a length. One of these is characterized in that it is possible to exchange different capillaries.

  According to a sixth aspect of the present invention, in the photomask foreign matter removing method according to any one of the first to fifth aspects, the suction action of the probe tip is a suction force by a vacuum pump, and the suction force is opened and closed by a valve. It is controlled by.

  The invention according to claim 7 is a photomask foreign matter removing apparatus for removing foreign matter adhering to the photomask, and obtains the three-dimensional information of the surface of the photomask and the foreign matter, and based on the three-dimensional information. A position specifying means for specifying the position of the foreign matter, a moving means for moving the probe tip to the position of the specified foreign matter, and moving the probe tip away from the photomask; and sucking the foreign matter with the probe tip And suction means capable of releasing suction.

  According to the present invention, since the tip of the probe is a fine thin tube, it is possible to deal with foreign matter that has entered a concave portion having a pattern with a half pitch of 45 nm or less. When the foreign matter is removed by suction, the pattern surface is not contacted, so that the pattern surface can be prevented from being damaged. Further, since the foreign matter is directly sucked, the subsequent cleaning step can be omitted.

  After the suction removal, the foreign matter attached to the probe tip can be removed by cleaning the probe tip. For this reason, it is possible to prevent reattachment of foreign matter adsorbed on the pattern surface.

  Since the probe itself can be exchanged, various pattern sizes can be used as long as the tips have different diameters.

It is the whole simplification figure at the time of imaging | photography of the foreign material removal apparatus which concerns on one Embodiment of this invention. It is the whole simplification figure at the time of the foreign material attraction | suction of the foreign material removal apparatus which concerns on one Embodiment of this invention. It is the whole simplification figure at the time of the foreign material removal of the foreign material removal apparatus which concerns on one Embodiment of this invention. It is a flow of the foreign substance removal method concerning one embodiment of the present invention.

  A foreign matter removing method and a foreign matter removing device according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the foreign matter removing method according to the present embodiment uses an AFM (Atomic Force Microscope) device as the foreign matter removing device. This AFM apparatus detects the displacement in the vertical direction of the cantilever 12 due to the atomic force or intermolecular force acting between the probe 11 and the sample (substrate 01), and images the sample surface shape.

  Specifically, the AFM apparatus at the time of imaging includes a probe head 15, a three-axis fine movement mechanism 21 using a piezoelectric element, a control device 22 that controls the three-axis fine movement mechanism 21, and a displacement amount of the cantilever 12 as displacement information. Z displacement amount feedback mechanism 23 obtained as follows, a semiconductor laser 24 that emits laser light toward the back surface of the cantilever 12, a photodetector 25 that detects reflected light reflected by the back surface of the cantilever 12, and the surface of the substrate 01 The optical camera 26 for photographing the pattern formed in the above, a valve 31, a vacuum pump 32, and a blower 41 are provided. The substrate 01 is set on a stage (not shown).

  The cantilever 12 is cantilevered at the other end opposite to the one end where the probe 11 is provided, and a three-axis fine movement mechanism 21 is provided at the other end. The triaxial fine movement mechanism 21 is controlled by the control device 22, and the cantilever 12 and the probe 11 held by the triaxial fine movement mechanism 21 can be driven in three directions of XYZ.

  The displacement amount of the cantilever 12 is detected by an optical lever measurement system. In the present embodiment, laser light is emitted from the semiconductor laser 24 toward the back surface of the cantilever 12, and a change in the optical path of the reflected light from the back surface of the cantilever 12 is detected by the light detector 25, thereby The amount of displacement is detected. Further, the displacement amount of the cantilever 12 detected by the photodetector 25 is fed back to the Z displacement amount feedback mechanism 23 as displacement information.

  In such a configuration, at the time of shooting, as shown in FIG. 4, the substrate 01 is set on the stage (ST1), and an approximate position is confirmed by using the optical camera 26 with any position of the substrate 01 as a target. After (ST2), the cantilever 12 is displaced up and down while controlling the triaxial fine movement mechanism 21 so that the displacement amount of the cantilever 12 is constant, and the surface of the substrate 01 is scanned by scanning the surface of the substrate 01. The three-dimensional information of the foreign object 02 is acquired (ST3). Based on these pieces of information, the position, shape, size and the like of the foreign object 02 are specified.

  Next, the AFM apparatus at the time of foreign matter suction according to the present invention will be described with reference to FIG. The probe 11 and the cantilever 12 have a hollow structure. The probe 11 includes a pedestal 13 fixed to the tip of the cantilever 12 and a thin tube 14 that passes through the pedestal 13. It is desirable that the thin tube 14 has a fine and hollow structure, and the length thereof is sufficiently longer than the depth A of the concave portion formed on the surface of the substrate 01. Moreover, as a material of the thin tube 14, a carbon nanotube etc. can be considered. The diameter of the carbon nanotube can be controlled in the manufacturing process if it belongs to the range of several nm to 10 nm for a single wall type and 10 nm to 100 nm for a multi wall type. Is possible. Therefore, multiple types (diameters) are prepared in advance according to the width of the concave portion of the mask pattern, and those having an appropriate diameter are adopted in accordance with the width of the concave portion and the size of the foreign matter 02 specified in the above-described photographing process. do it.

  Therefore, the cantilever 12 according to the present embodiment can replace the probe 11 with another probe by, for example, a magnetic force in order to appropriately select the above-described thin tubes 14 having a plurality of diameters (and lengths). The reason for the exchange by magnetic force is to prevent the probe 11 from being detached from the cantilever 12 even when the valve 31 is closed and the suction is released. At this time, it is preferable to use an electromagnet for the probe head 15 and control the magnetic force by turning the current on and off. In order to join the cantilever 12 and the probe 11 with an electromagnet, it is desirable that both the cantilever 12 and the probe 11 are made of a magnetic material. Moreover, in order to implement | achieve stable joining, the base 13 is provided in the edge part on the opposite side to the front-end | tip of the thin tube 14 of the probe 11. FIG. The pedestal 13 has a conical shape, and allows the thin tube 14 and the cantilever 12 to communicate with each other by passing the thin tube 14 so as to penetrate the center, and the thin tube 14 is held in a state extending along the vertical direction without being inclined. Is possible. By adopting this structure, it is possible to easily grasp the relative positional relationship between the side wall of the concave portion of the substrate 01 and the foreign matter 02. Furthermore, the opening C at the tip of the cantilever 12 is desirably larger than the opening B of the pedestal 13 in order to prevent inability to suck due to positional deviation.

  A hollow portion inside the cantilever 12 is connected to a vacuum pump 32 via a probe head 15, and suction by the thin tube 14 can be controlled by opening and closing the valve 31. The valve 31 is kept closed except for the foreign matter suction operation and the foreign matter holding operation.

  In such a configuration, when sucking the foreign matter 02, as shown in FIG. 4, at the start of suction with the valve 31 opened (ST4), the surface of the substrate 01 and the foreign matter specified earlier (ST1 to ST3) After determining the approach position of the probe 11 and the approach amount in the depth direction based on the three-dimensional information of 02, the probe 11 is approached to the foreign object 02 with the determined values (ST5). Then, at the moment when the probe 11 (the thin tube 14) comes into contact with the foreign material 02, the foreign material 02 is adsorbed by the thin tube 14. With the foreign matter 02 adsorbed on the thin tube 14, the probe 11 is pulled up together with the cantilever 12 to remove the foreign matter 02 that has entered the recess of the substrate 01. In selecting the thin tube 14, the one that can be retained at the tip of the thin tube 14 when the foreign material 02 is sucked is used in consideration of the width of the recess and the size of the foreign material 02.

  Further, the foreign matter 02 sucked up by the thin tube 14 is removed using blow cleaning as shown in FIG. The tip of the blower 41 is hollow and is connected to a blower blower or the like (not shown).

  First, the pulled capillary 14 is moved out of the range of the substrate 01 (ST6), and the valve 31 is closed from the open state with the tip of the blower 41 approaching the foreign object 02, thereby closing the capillary 14 The suction state by is released (ST7). As a result, the suction of the foreign matter 02 by the thin tube 14 is released, and at the same time, the foreign matter 02 sucked by the thin tube 14 by the blower from the blower 41 is removed from the thin tube 14 (ST8). As the gas blown from the blower 41, it is desirable to use an inert gas such as nitrogen or helium so that the thin tube 14 does not deteriorate. Thereby, the reattachment of the foreign matter 02 to the substrate 01 can be prevented.

In the present embodiment, the probe head 15, the triaxial fine movement mechanism 21, the control device 22, the Z displacement amount feedback mechanism 23, the semiconductor laser 24, the photodetector 25, and the optical camera 26 are included in the photomask. A position specifying unit that acquires three-dimensional information of the surface and the foreign matter and specifies the position of the foreign matter based on the three-dimensional information is configured.
Further, the triaxial fine movement mechanism 21 and the control device 22 constitute moving means for moving the probe tip to the position of the specified foreign matter and separating the probe tip from the photomask.
The control device 22, the valve 31, and the vacuum pump 32 constitute suction means that can suck and release the foreign matter at the probe tip.

DESCRIPTION OF SYMBOLS 01 ... Board | substrate 02 ... Foreign material 11 ... Probe 12 ... Cantilever 13 ... Base 14 ... Narrow tube 15 ... Probe head 21 ... Triaxial fine movement mechanism 22 ... Control apparatus 23 ... Z displacement amount feedback mechanism 24 ... Semiconductor laser 25 ... Photodetector 26 ... Optical camera (photographing means)
31 ... Valve 32 ... Vacuum pump (suction means)
41 ... Blower (removal means)
A ... Surface depth of substrate 01 B ... Diameter of capillary 14 C ... Opening at tip of cantilever 12

Claims (7)

A foreign matter removing method of a photomask for removing foreign matter attached to a photomask,
Obtaining the three-dimensional information of the surface of the photomask and the foreign matter, and identifying the position of the foreign matter based on the three-dimensional information;
Moving the probe tip based on the position of the identified foreign matter, sucking the foreign matter with the probe tip, and then removing the foreign matter from the photomask by separating the probe tip from the photomask; ,
Releasing the suction and removing the foreign matter sucked at the probe tip from the probe tip;
A method for removing foreign matter from a photomask, comprising:   2. The method for removing foreign matter from a photomask according to claim 1, wherein the probe tip comprises a hollow thin tube.   The method for removing foreign matter from a photomask according to claim 2, wherein the material of the narrow tube is a carbon nanotube, and the diameter thereof is several nm to 100 nm.   The photomask according to any one of claims 1 to 3, wherein in the step of removing the foreign matter sucked by the probe tip from the probe tip, gas is blown toward the foreign matter at the probe tip. Foreign matter removal method. The probe has a pedestal that supports the capillary tube,
The method for removing foreign matter from a photomask according to any one of claims 2 to 4, wherein the pedestal is configured such that at least one of tubes having different diameters or lengths can be exchanged.   The method for removing foreign matter from a photomask according to claim 1, wherein the suction action of the probe tip is a suction force by a vacuum pump, and the suction force is controlled by opening and closing a valve. A photomask foreign matter removing apparatus for removing foreign matter attached to a photomask,
Obtaining the three-dimensional information of the surface of the photomask and the foreign matter, and position specifying means for specifying the position of the foreign matter based on the three-dimensional information;
A moving means for moving the probe tip to the position of the specified foreign matter, and for moving the probe tip away from the photomask;
A suction means capable of suctioning and releasing suction of the foreign matter at the probe tip;
An apparatus for removing foreign matter from a photomask, comprising:

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