JP2010016192A - Charged particle beam lithography system and electrically charged particle beam drawing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithography system that can reduce the deviation of an error of a shot position between chips. <P>SOLUTION: A lithography system 100 has an electron gun 201 for emitting electron beams 200, an XY stage 105 for placing a test sample 101, a deflector 208 for deflecting the electron beams 200 over the test sample 101, a BLK aperture 218 arranged at the side of the XY stage 105 rather than the deflector 208 side to shield the electron beams 200, and a BLK deflector 216 arranged at the side of the stage rather than the deflector 208 side to deflect the electron beams 200 passing through the deflector 208 over the BLK aperture 218. According to this invention, the deviation of the error of the shot position between chips can be reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charged particle beam drawing apparatus and a charged particle beam drawing method, for example, to a drawing apparatus and method for drawing a plurality of chip regions on a sample.

  Lithography technology, which is responsible for the progress of miniaturization of semiconductor devices, is an extremely important process for generating a pattern among semiconductor manufacturing processes. In recent years, with the high integration of LSI, circuit line widths required for semiconductor devices have been reduced year by year. In order to form a desired circuit pattern on these semiconductor devices, a highly accurate original pattern (also referred to as a reticle or a mask) is required. Here, the electron beam (electron beam) drawing technique has an essentially excellent resolution, and is used for producing a high-precision original pattern.

FIG. 5 is a conceptual diagram for explaining the operation of the variable shaping type electron beam drawing apparatus.
The variable shaped electron beam (EB) drawing apparatus operates as follows. First, the first aperture 410 is formed with a rectangular opening 411 for forming the electron beam 330. Further, the second aperture 420 is formed with a variable shaping opening 421 for shaping the electron beam 330 that has passed through the opening 411 into a desired rectangular shape. The electron beam 330 irradiated from the charged particle source 430 and passed through the opening 411 is deflected by a deflector. And it passes through a part of variable shaping | molding opening 421, and is irradiated to the sample mounted on the stage. The stage continuously moves in a predetermined direction (for example, the X direction) during drawing. Thus, a rectangular shape that can pass through both the opening 411 and the variable shaping opening 421 is drawn in the drawing region of the sample 340. A method of creating an arbitrary shape by passing both the opening 411 and the variable forming opening 421 is referred to as a variable forming method.

  The electron beam for one shot that is variably shaped is deflected by a deflector to irradiate a desired position on the sample. The electron beam for the next shot is similarly variably shaped, then deflected by the deflector, and irradiated to the next shot position on the sample. By repeating this, a predetermined pattern is formed on the sample. Each shot is formed by repeating the operation of shielding the electron beam with a blanking aperture at a high speed (blanking ON) and the operation of passing the blanking aperture (blanking OFF) with respect to the electron beam. (For example, refer to Patent Document 1). The electron beam at the time of passage becomes an electron beam for one shot. The interval between ON and OFF is as short as several tens to several hundreds nsec. Normally, this blanking is performed on the upstream side of the deflector that deflects the electron beam to a desired position on the sample. Therefore, the electron beam reaches the deflector while the electron beam is shielded between shots. There will be no.

  Here, a plurality of chip patterns are often drawn on one sample to be drawn. In that case, after the first chip pattern is drawn in the first chip area, the irradiation position is moved to the second chip area, and then the second chip pattern is drawn in the second chip area. Is done. The time required for this movement may be in seconds. Conventionally, an electron beam is shielded by a blanking aperture during movement between the chip regions.

  FIG. 6 is a conceptual diagram for explaining an example of a beam trajectory when contaminants adhere to the deflector. In FIG. 6, the configuration for variably shaping the beam is omitted. The electron beam 304 emitted from the electron gun 302 passes through the blanking aperture 310 when the electron beam 304 is not deflected by the blanking deflector 308 (blanking OFF), and the sample on the stage 316 is deflected by the deflector 314. It is deflected to a desired position on 318. Then, the electron beam 304 is focused by the objective lens 312 and irradiated on a desired position on the sample 318. When the sample 318 is not irradiated with the electron beam, the blanking deflector 308 deflects the electron beam 304 onto the blanking aperture 310 and blocks it (blanking ON).

Here, if the contaminant 320 (contamination) adheres to the inside of the deflector 314 or the like, the contaminant 320 is charged when the electron beam 304 passes near the deflector 314. A new electric field is generated by the charging of the contaminant 320, thereby causing a shift in the trajectory of the electron beam 304. However, since the interval between shots is usually short as described above while drawing in the same chip area, even if the contaminant 320 is charged, the state of charging between the previous and subsequent shots is substantially reduced. It does not change. In other words, it remains almost stationary. For this reason, the deviation of the irradiation position between shots does not occur or becomes a minute amount. However, when the irradiation position is moved from the first chip area to the second chip area, the electron beam is blocked by the blanking aperture 310 in units of seconds. The beam 304 does not reach. For this reason, the charges charged in the contaminant 320 are discharged while being shielded. As a result, the first chip area is drawn in a state where the contaminant 320 is charged, whereas the second chip area is drawn in a state where the contaminant 320 is not charged. Therefore, the trajectory of the electron beam 304 changes between when the contaminant 320 is charged and when it is not charged. As a result, the irradiation position on the sample 318 causes a positional deviation ΔL. Therefore, in order to make the trajectory of the electron beam close to a constant value, conventionally, the contaminated deflector is cleaned or replaced with a new one.
JP 2007-271919 A

  As described above, when each chip pattern is drawn in a plurality of chip areas, there is a problem that a large deviation in shot position error occurs between chips. With the recent miniaturization of patterns, such a shift becomes a big problem. As in the prior art, when the contaminated deflector is cleaned or replaced with a new one, the apparatus must be stopped temporarily, which shortens the apparatus operation time, which leads to deterioration in throughput. Therefore, it is desirable to establish a technique that eliminates the need for such cleaning or replacement work. However, conventionally, an effective means for solving this problem has not been established.

  Accordingly, an object of the present invention is to provide a drawing apparatus and method that can overcome such problems and reduce deviations in shot position errors between chips.

A charged particle beam drawing apparatus according to one embodiment of the present invention includes:
An emission part for emitting a charged particle beam;
A stage on which a sample is placed;
A first deflector for deflecting a charged particle beam onto the sample;
A shielding part that is arranged on the stage side of the first deflector and shields the charged particle beam;
A second deflector disposed on the stage side of the first deflector and deflecting the charged particle beam that has passed through the first deflector onto the shielding portion;
It is provided with.

  With this configuration, the second deflector deflects the charged particle beam that has passed through the first deflector onto the shielding portion. Therefore, if the charged particle beam is shielded by deflecting the charged particle beam onto the shielding portion with the second deflector during the movement between the chips, the first deflector is also used during the movement between the chips. A charged particle beam has arrived. Therefore, the first deflector continues to be charged by the charged particle beam both when drawing the chip before movement and when drawing the chip after movement.

The charged particle beam lithography system
Another shielding part that is disposed closer to the emitting part than the first deflector and shields the charged particle beam;
A third deflector that is disposed closer to the emission unit than the first deflector and deflects the charged particle beam before passing through the first deflector onto the above-described another shielding unit;
It is preferable to further include

  The deflector length of the second deflector is shorter than the deflector lengths of the first and third deflectors.

Each of the first to third deflectors has a pair of opposing deflection electrodes,
The distance between the pair of deflection electrodes of the second deflector is longer than the distance between the pair of deflection electrodes of the first and third deflectors.

  The voltage applied to the second deflector is larger than the voltage applied to the first and third deflectors.

The charged particle beam drawing method of one embodiment of the present invention includes:
Emitting a charged particle beam;
Deflecting the charged particle beam onto the sample by a deflector;
Shielding the charged particle beam after passing through the deflector before reaching the sample when changing the irradiation position of the charged particle beam from the first tip region to the second tip region on the sample;
It is provided with.

  According to the present invention, it is possible to reduce an error in shot position error between chips. As a result, a plurality of chip patterns can be drawn with high accuracy.

  Hereinafter, in the embodiment, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and may be a beam using other charged particles such as an ion beam.

Embodiment 1 FIG.
FIG. 1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to the first embodiment.
In FIG. 1, the drawing apparatus 100 includes a drawing unit 150 and a control unit 160. The drawing apparatus 100 is an example of a charged particle beam drawing apparatus. The drawing apparatus 100 draws a desired pattern on the sample 101. The drawing unit 150 includes an electron column 102 and a drawing chamber 103. In the electron column 102, there are an electron gun 201 (emission part), an illumination lens 202, a blanking (BLK) deflector 212 (third deflector), a blanking (BLK) aperture 214 (another shielding part), First aperture 203, projection lens 204, deflector 205, second aperture 206, objective lens 207, deflector 208 (first deflector), BLK deflector 216 (first deflector), and BLK aperture 218 (shielding part) is arranged. In the drawing chamber 103, an XY stage 105 is arranged so as to be movable. A sample 101 is disposed on the XY stage 105. Examples of the sample 101 include an exposure mask substrate that transfers a pattern onto a wafer. The mask substrate includes mask blanks on which nothing is drawn yet.

  The BLK deflector 212 is arranged closer to the electron gun 201 (upstream side) than the BLK aperture 214. The BLK aperture 214 is closer to the electron gun 201 than the first aperture 203, the projection lens 204, the deflector 205, the second aperture 206, the objective lens 207, the deflector 208, the BLK deflector 216, and the BLK aperture 218. (Upstream side) The BLK deflector 216 is disposed closer to the electron gun 201 (upstream side) than the BLK aperture 218. The BLK deflector 216 and the BLK aperture 218 include the first aperture 203, the projection lens 204, the deflector 205, the second aperture 206, the objective lens 207, the deflector 208, the BLK deflector 216, and the BLK aperture 218. Is also arranged on the XY stage 105 side (downstream side).

  The control unit 160 includes a deflection control circuit 120, a control computer 110, and DAC (digital / analog conversion) amplifiers 122, 124, 126, and 128. A memory 112 and a deflection control circuit 120 are connected to the control computer 110 via a bus (not shown). The deflection control circuit 120 is connected to the DAC amplifiers 122, 124, 126, and 128. The DAC amplifier 122 is connected to the BLK deflector 212, the DAC amplifier 124 is connected to the deflector 205, the DAC amplifier 126 is connected to the deflector 208, and the DAC amplifier 128 is connected to the BLK deflector 216. Information input to the control computer 110 or information during and after the arithmetic processing is stored in the memory 112 each time.

  In FIG. 1, constituent parts necessary for explaining the first embodiment are described. It goes without saying that the drawing apparatus 100 usually includes other necessary configurations.

  An electron beam 200 is emitted (irradiated) from the electron gun 201. The electron beam 200 emitted from the electron gun 201 illuminates the entire first aperture 203 having a rectangular hole, for example, a rectangular hole, by the illumination lens 202. Here, the electron beam 200 is first formed into a rectangle, for example, a rectangle. Then, the electron beam 200 of the first aperture image that has passed through the first aperture 203 is projected onto the second aperture 206 by the projection lens 204. The position of the first aperture image on the second aperture 206 is deflection-controlled by the deflector 205, and the beam shape and size can be changed. As a result, the electron beam 200 is shaped. Then, the electron beam 200 of the second aperture image that has passed through the second aperture 206 is focused by the objective lens 207 and deflected by the deflector 208. As a result, the desired position of the sample 101 on the continuously moving XY stage 105 is irradiated.

  Here, when the electron beam 200 on the sample 101 reaches the irradiation time t in which a desired irradiation amount is incident on the sample 101, blanking is performed as follows. That is, in order to prevent the sample 101 from being irradiated with the electron beam 200 more than necessary, for example, the electron beam 200 is deflected by the electrostatic BLK deflector 212 and the electron beam 200 is cut by the BLK aperture 214. This prevents the electron beam 200 from reaching the surface of the sample 101. The deflection voltage of the BLK deflector 212 is controlled by the deflection control circuit 120 and the DAC amplifier 122.

  When the beam is ON (blanking OFF), the electron beam 200 emitted from the electron gun 201 follows the trajectory indicated by the solid line in FIG. On the other hand, in the case of beam OFF (blanking ON), the electron beam 200 emitted from the electron gun 201 travels on the trajectory indicated by the dotted line in FIG. 1 before the BLK aperture 214. In addition, the inside of the electron column 102 and the drawing chamber 103 are evacuated by a vacuum pump (not shown) to form a vacuum atmosphere in which the pressure is lower than the atmospheric pressure. From the start of passing through the BLK aperture 214 due to blanking ON until the blocking by blanking OFF, the electron beam 200 for one shot is obtained.

  FIG. 2 is a diagram illustrating an example of a chip area to be drawn in the first embodiment. FIG. 2 shows a case where the chip pattern of chip A and the chip pattern of chip B are drawn in the drawing area 10 on the sample 101, for example. The chip pattern of the chip A is drawn in the chip area 14. The chip pattern of the chip B is drawn in the chip area 12. When drawing such a plurality of chip patterns, the first chip pattern is drawn by dividing the shape of the first chip pattern into a plurality of figures and shooting each figure on the first chip area. Thereafter, the irradiation position is moved to the second chip area, and then the second chip pattern is divided by dividing the shape of the second chip pattern into a plurality of figures and each figure is shot in the second chip area. Is drawn. In FIG. 2, the chip pattern of the chip A is drawn on the chip area 14 in each shot of the chip pattern of the chip A, and the irradiation position is moved from the final irradiation position P to the irradiation start position Q of the second chip area 12. When the XY stage 105 moves to a position where it can be deflected by the deflector 208, the irradiation position is moved. Then, the chip pattern of the chip B is drawn in the chip area 12 by each shot of the chip pattern of the chip B. Here, if the moving speed of the XY stage 105 is 50 mm / sec and the distance between the PQs is 100 mm, the time required for moving between the chips is 2 sec. On the other hand, the interval between shots in the same chip area is very short, for example, several tens to several hundreds nsec.

  Here, if contaminants 20 (contamination) adhere to an optical system downstream of the BLK aperture 214, for example, the inside of the deflector 205 or the deflector 208, the vicinity of the deflector 205 or the deflector 208 is observed. When the electron beam 304 passes, the contaminant 20 is charged. A new electric field is generated due to the charging of the contaminant 20, thereby causing a shift in the trajectory of the electron beam 200. Therefore, if the contaminant 20 has already adhered to the inside of the deflector 205 or the deflector 208 at the time when the drawing of the sample 101 is started, this contaminant is soon to be drawn in the chip pattern of the chip A on the chip region 14. 20 is charged. Then, while the chip pattern of the chip A is drawn on the chip region 14, the electron beam 200 is constantly affected by the electric field due to the charging of the contaminant 20. As described above, since the blanking ON / OFF interval between shots is as short as several tens to several hundreds nsec, for example, the contaminant 20 repeats only slight discharge and charge, and the charge is substantially reduced. This is because the situation does not change. For this reason, the deviation of the irradiation position between shots does not occur or becomes a minute amount. However, this is a problem because the time required for movement between chips is 2 sec.

  When operating by the conventional method, the electron beam 200 is shielded by the BLK aperture 214 for 2 seconds. For this reason, the electron beam 200 does not reach the optical system downstream of the BLK aperture 214, for example, the deflector 205 or the deflector 208 for 2 seconds. Therefore, during the movement between the chips AB, the electric charges are discharged from the contaminant 20 attached to the deflector 205 or the deflector 208, and the electric field disappears. Therefore, the electric field received by the electron beam 200 is different between when the drawing is performed on the chip region 14 and when the drawing is started on the chip region 12. For this reason, when drawing is started on the chip region 12, the irradiation position of the electron beam 200 largely deviates from that.

  On the other hand, in the first embodiment, the electron beam 200 is blocked by the BLK aperture 214 between shots while drawing in the same chip area, but the electron beam is blocked by the BLK aperture 218 when moving between chips. Shield 200. That is, the electron beam 200 that has passed through the deflectors 205 and 208 is deflected onto the BLK aperture 218 by the BLK deflector 216 so that the electron beam 200 is shielded before reaching the sample 101. Therefore, unlike the conventional method, the electron beam 200 continues to pass through an optical system upstream of the BLK aperture 218, for example, near the deflector 205 or the deflector 208, during movement between chips. Therefore, the charged state of the contaminant 20 is maintained. Therefore, the electric field caused by the contaminant 20 remains the same at the time when drawing is performed on the chip region 14 and when the drawing is started on the chip region 12. Therefore, it is possible to prevent the irradiation position of the electron beam 200 from being deviated from when the drawing is started on the chip region 12 until then.

FIG. 3 is a graph showing an example of a change in position error between the first embodiment and the prior art.
In FIG. 3, when the electron beam 200 is blocked by the BLK aperture 214 using the conventional method, as shown in the graph 32, when moving from the chip A to the chip B, a large deviation (ΔL ) May occur. On the other hand, when the electron beam 200 is shielded by the BLK aperture 218 arranged on the most downstream side of the electron column 102 as in the first embodiment, as shown by the graph 30, the transition is performed with the same position error until then. However, it is possible to avoid a particularly large deviation.

  FIG. 4 is a diagram illustrating an example of the deflector length of the deflector and the distance between the deflection electrodes in the first embodiment. Each of the BLK deflectors 212 and 216 and the deflectors 205 and 208 includes at least a pair of deflecting electrodes facing each other. Here, a two-pole type is shown as an example, but it is particularly preferable to use a four-pole or eight-pole type for the deflectors 205 and 208. The BLK deflectors 212 and 216 need only have two poles as long as they can block the electron beam 200. The BLK deflector 216 may be as slow as 2 seconds, for example, 2 seconds, between blanking ON / OFF, the BLK deflector 212 that performs ON / OFF between shots, and the deflector 205 that changes the deflection position between shots. Unlike 208, high-speed response is unnecessary. Therefore, the deflector length of the BLK deflector 216 can be shorter than the deflector lengths of the other BLK deflector 212 and deflectors 205 and 208. That is, the relationship of L4 <L1, L2, L3 may be sufficient. Therefore, the installation space can be small. Therefore, enlargement of the electronic lens barrel 102 can be avoided. Further, it is preferable that the distance between the pair of deflection electrodes of the BLK deflector 216 is longer than the distance between the pair of deflection electrodes of the other BLK deflector 212 and the deflectors 205 and 208. . That is, the relationship d4> d1, d2, d3 may be sufficient. With this configuration, even if the contaminant 20 adheres to the BLK deflector 216, the influence of the electric field due to the charge of the contaminant 20 on the electron beam 200 can be reduced. Then, the applied voltage to the BLK deflector 216 may be made larger than the applied voltages to the other BLK deflector 212 and the deflectors 205 and 208 as the distance between the electrodes is increased. For example, the voltage applied to the BLK deflector 216 is made larger than 250V. The applied voltage to the other BLK deflector 212 and deflectors 205 and 208 is, for example, 20 to 250V.

  As described above, by shielding the electron beam 200 for movement between chips on the side closer to the sample 101, the electric field state on the upstream side can be maintained. Therefore, it is possible to reduce a deviation in shot position error between chips. As a result, a plurality of chip patterns can be drawn with high accuracy. In addition, it is possible to save the trouble of cleaning and replacing the deflector due to the adhesion of contaminants.

  The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the BLK aperture 214 is disposed on the upstream side of the first aperture 203, but the present invention is not limited to this. For example, the BLK aperture 214 may be disposed on the downstream side of the second aperture 206. A mechanism in which contaminants adhere to the downstream side of the BLK aperture 214 that blocks the electron beam 200 between shots, for example, a deflector 208 exists, and the electron beam 200 is transmitted between the chips downstream of the mechanism to which such contaminants adhere. A BLK aperture 218 for shielding may be disposed.

  Further, ON / OFF by the BLK deflector 216 and the aperture 218 is not limited to the movement between the chips, but blocks the electron beam 200 for a time longer than the time when the charges charged on the contaminants attached to the optical system are discharged. It can be used when Further, the time required for movement between the chips is not limited to 2 seconds or more, and may be any time as long as the charge charged in the contaminant is discharged. For example, if it is 1 sec or longer, it is expected to be similarly discharged.

  In addition, although descriptions are omitted for parts and the like that are not directly required for the description of the present invention, such as a device configuration and a control method, a required device configuration and a control method can be appropriately selected and used. For example, although the description of the control unit configuration for controlling the drawing apparatus 100 is omitted, it goes without saying that the required control unit configuration is appropriately selected and used.

  In addition, all charged particle beam writing methods and apparatuses that include elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 1. FIG. 6 is a diagram illustrating an example of a chip area to be drawn in the first embodiment. FIG. It is a graph which shows an example of a change of a position error between Embodiment 1 and the past. 6 is a diagram illustrating an example of a deflector length of a deflector and a distance between deflection electrodes in the first embodiment. FIG. It is a conceptual diagram for demonstrating operation | movement of the conventional variable shaping type | mold electron beam drawing apparatus. It is a conceptual diagram for demonstrating an example of the beam track | orbit when a contaminant adheres to a deflector.

Explanation of symbols

10 Drawing region 12, 14 Chip region 20, 320 Contaminant 30, 32 Graph 100 Drawing device 101, 318, 340 Sample 102 Electronic column 103 Drawing chamber 105 XY stage 110 Control computer 112 Memory 120 Deflection control circuit 122, 124, 126 , 128 DAC amplifier 150 Drawing unit 160 Control unit 200, 304 Electron beam 201, 302 Electron gun 202 Illumination lens 203, 410 First aperture 204 Projection lens 205, 208, 314 Deflector 206, 420 Second aperture 207 Objective lens 212, 216, 308 BLK deflectors 214, 218, 310 BLK aperture 316 Stage 330 Electron beam 411 Opening 421 Variable shaped opening 430 Charged particle source

Claims (6)

An emission part for emitting a charged particle beam;
A stage on which a sample is placed;
A first deflector for deflecting the charged particle beam onto the sample;
A shielding part that is disposed on the stage side of the first deflector and shields the charged particle beam;
A second deflector disposed on the stage side of the first deflector and deflecting the charged particle beam that has passed through the first deflector onto the shielding portion;
A charged particle beam drawing apparatus comprising: Another shielding part that is disposed closer to the emitting part than the first deflector and shields the charged particle beam;
A third deflector that is disposed closer to the emission part than the first deflector and deflects the charged particle beam before passing through the first deflector onto the other shielding part;
The charged particle beam drawing apparatus according to claim 1, further comprising:   3. The charged particle beam drawing apparatus according to claim 2, wherein a deflector length of the second deflector is shorter than a deflector length of the first and third deflectors. The first to third deflectors each have a pair of opposing deflection electrodes,
The distance between the pair of deflection electrodes of the second deflector is longer than the distance between the pair of deflection electrodes of the first and third deflectors. Charged particle beam lithography system.   5. The charged particle beam drawing apparatus according to claim 2, wherein an applied voltage to the second deflector is higher than an applied voltage to the first and third deflectors. Emitting a charged particle beam;
Deflecting the charged particle beam onto the sample by a deflector;
When changing the irradiation position of the charged particle beam from the first chip region on the sample to the second chip region, the charged particle beam after passing through the deflector is shielded before reaching the sample. And a process of
A charged particle beam drawing method comprising:

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