JP4761508B2 - Charged particle exposure apparatus and device manufacturing method - Google Patents

Description

  The present invention relates to a charged particle beam exposure apparatus such as an electron beam exposure apparatus and an ion beam exposure apparatus mainly used for exposure of a semiconductor integrated circuit, and more particularly to a raster scan type that performs pattern drawing using a plurality of charged particle beams. The present invention relates to a charged particle beam exposure apparatus and a device manufacturing method using the charged particle beam exposure apparatus.

When manufacturing microdevices (semiconductor chips such as IC and LSI, liquid crystal panels, CCDs, thin film magnetic heads, micromachines, etc.), a conventional charged particle beam exposure apparatus for forming a pattern on a sample uses a charged particle source. A desired pattern is formed on the sample by accelerating, shaping, reducing the emitted charged particles and irradiating the sample with a beam. In a certain type of exposure apparatus, the beam has a certain area, is shaped into a desired rectangle, a desired pattern, or a desired plurality of beams, and is irradiated onto the sample.
In many of the charged particle beam exposure apparatuses described above, after a certain portion of the sample is exposed, the beam irradiation is temporarily stopped, the position on the sample to be irradiated next is calculated, further corrected, and the deflector A desired current or voltage is applied to the laser beam, and beam irradiation is performed again after the current or voltage value is stabilized.
Drawing of one sample is a repetition of the above operations. In recent years, it has been desired to improve the throughput of the charged particle beam exposure apparatus, and for that purpose, various measures have been taken to shorten the cycle. The beam irradiation time to the sample has been shortened by increasing the beam current and improving the resist sensitivity, etc., but the shortening of the time when the sample is not exposed to the beam has been optimized especially for the raster scan type exposure apparatus. There wasn't.
Japanese Patent Laying-Open No. 2005-32888 (Patent Document 1) proposes a “charged particle beam exposure apparatus and a charged particle beam exposure method”. In an illumination optical system of the exposure apparatus, an illumination beam is sent to each subfield of the reticle. A main deflector that deflects toward the reticle and a blanking deflector that blanks the illumination beam so as not to hit the reticle, and controls the blanking deflector to change the blanking time, and Since exposure can be performed even during acceleration / deceleration of the reticle stage, the throughput of the apparatus can be improved.
JP 2005-32888 A

In the raster scan type exposure apparatus, since the clock for turning on and off the beam was constant, sufficient consideration was not given to changes in the charged particle beam current amount, changes in resist sensitivity, and changes in exposure amount due to proximity effect correction. .
In other words, since the clock is constant even when the exposure dose changes, the sum of the charged particle beam irradiation time and charged particle beam irradiation time is always constant even if the charged particle beam irradiation dose is shortened. Yes, the drawing time was not shortened.
Therefore, the present invention uses a raster scan type charged particle exposure apparatus and its charged particle beam exposure apparatus that reduce the drawing time of the sample by shortening the time during which the sample is not irradiated with the charged particle beam and improve the throughput. An object is to provide a device manufacturing method.

The charged particle beam exposure device of the present invention in order to achieve the above object, a charged particle beam exposure apparatus for performing exposure by irradiating the beam onto the sample on which the resist is applied from a charged particle source, said beam deflect, and blanking means for controlling the irradiation onto the sample in the beam, to deflect the beam, and a deflector for scanning the beam over the sample, said blanking means and the deflector , the beam is operated with an exposure cycle time and the beam is irradiated is expressed by the sum of time that is not irradiated onto the sample on the sample, the exposure cycle, the beam current data, resist sensitivity data and proximity seek time the more effective correction data beam is irradiated onto the sample, such that said beam in response to the result to reduce the time that is not irradiated onto the sample, Characterized in that it is strange setting.

According to the charged particle beam exposure apparatus of the present invention, the exposure cycle is controlled by controlling the blanker and the deflector so as to reduce the time during which the sample is not irradiated with the charged particle beam within the time for exposing one sample. Since it is changed, the drawing time of the sample is shortened and the throughput is improved.
Furthermore, according to the device manufacturing method of the present invention, since the charged particle beam exposure apparatus is used, the drawing time of the sample is shortened, the throughput is improved, and the device manufacturing efficiency is improved.

  Hereinafter, the present invention will be described with reference to the drawings based on the embodiments.

The charged particle beam exposure apparatus according to the first embodiment of the present invention will be described below.
A raster scan type multi-electron beam exposure apparatus is shown as the raster scan type charged particle beam exposure apparatus of the first embodiment of the present invention.
Note that the present invention can be similarly applied to an exposure apparatus using an ion beam as well as a charged particle beam that is an electron beam, and the same effect can be obtained not only for a multi-electron beam but also for a single beam.
FIG. 1 is a schematic configuration diagram of a main part of a charged particle beam exposure apparatus according to a first embodiment of the present invention.
A charged particle beam 10, which is an electron beam emitted radially from the electron source 1, is formed into an area beam having a desired size by the collimator lens 2, and is then substantially perpendicularly incident on the mask 3. The mask 3 is a mask having a plurality of patterns. The charged particle beam 10 formed through the mask 3 is converged on the blanking array 6 by the lens array 4. The blanking array 6 is a deflecting plate array and can deflect the beam individually. The beam deflected by the blanking array 6 is shielded by the blanking diaphragm 9, but the beam not deflected by the blanking array 6 is reduced by the lenses 7 and 8 and irradiated to a desired position on the sample 11 by the deflector 5. Is done.
On the other hand, drawing data for drawing is transferred from the controller 12 to the drawing pattern generation circuit 14, and thereafter converted into a bitmap by the bitmap conversion circuit 15, and the blanking time of each beam is calculated by the exposure time control circuit 16. Then, a control signal is applied to each blanking array 6 by the blanking control circuit 17. In addition, a desired lens current and a lens voltage are calculated for the lenses 2, 4, 7, and 8 from the lens control circuit 13, and a desired signal of the sample 11 is calculated for the deflector 5 by the deflection signal generation circuit 18 and the deflection amplifier 19. A deflection voltage to be irradiated with the charged particle beam 10 is applied to the position.

The details of the operations of the blanking array 6 and the deflector 5 constituting the raster scan type charged particle beam exposure apparatus according to the conventional example and the first embodiment of the present invention will be described with reference to FIGS. explain. The time change of the voltage applied to the blanking array 6 is shown in FIGS.
When no voltage is applied to the blanking array 6, drawing is performed because the charged particle beam 10 reaches the sample 11. However, when a voltage is applied, drawing is performed because the beam is shielded by the blanking diaphragm 9. I will not.
2A, 2B, and 2C show the case of all the fill patterns, but the same applies to the case of other patterns.
The blanking array 6 operates in a predetermined exposure cycle 21 and irradiates the charged particle beam 10 during the beam irradiation times 20a and 20b set for a time within one clock.
As shown in FIG. 2A, when the beam irradiation time 20a is substantially the same as one clock time, drawing can be performed efficiently.
However, in the conventional raster scan type charged particle beam exposure apparatus shown in FIG. 2 (b) due to an increase in beam current, improvement in resist sensitivity, etc., a clock is required when a short beam irradiation time 20b is required. The beam irradiation time 20b is short with respect to the exposure cycle 21 which is time, and the time 20c when the charged particle beam 10 is not irradiated increases. The time 20c when the charged particle beam 10 is not irradiated is a waiting time, and the use efficiency of the apparatus decreases as the waiting time becomes longer. However, when the exposure cycle 21 is constant, the beam irradiation time to the sample 11 can be controlled, but the total time required for drawing cannot be shortened.
An example of blanking control of the charged particle beam exposure apparatus according to the first embodiment of the present invention for solving the above problem is shown in FIG.
In the first embodiment, the exposure clock is optimized according to the beam current and resist sensitivity. That is, in the system with a large beam current and high resist sensitivity, as shown in FIG. 2C, the exposure cycle 21a is changed at high speed, and in the system with a small beam current and low sensitivity, as shown in FIG. The exposure cycle 21 is changed to a low speed to change the time 20d during which the charged particle beam 10 is not irradiated as short as possible. The optimum exposure cycles 21 and 21a are calculated and set from the beam current and resist sensitivity. That is, the deflector operates in an exposure cycle represented by the sum of the time when the charged particle beam is irradiated on the sample and the time when the sample is not irradiated, and the exposure cycle can be set variably.

FIG. 3 shows details of a control circuit for calculating optimum exposure clocks 21 and 21a of the charged particle beam exposure apparatus according to the first embodiment of the present invention.
Necessary exposure time calculation 24 is performed from the bitmap data transferred from the bitmap conversion circuit 15 and the preset resist sensitivity data 23 and the preset or measured beam current data 22. When the exposure time is calculated, the optimum exposure cycles 21 and 21a based on the exposure time are calculated by the optimum exposure cycle calculation 25 and transferred to the individual blanking control circuit 17. At the same time, when the exposure cycle changes, the scanning time of the charged particle beam 10 also changes, so that the data is also sent to the deflection signal generation circuit 18.
The above series of operations is performed for each scanning of the charged particle beam 10, and the exposure cycles 21 and 21a are optimized for each scanning.
Was subjected to drawing using a multi-electron beam exposure apparatus according to the above configuration, the total beam current 1 microampere, 7 drawing time was also spent one hour in the case of any of microamps when the beam current 1 microampere In the case of 1 hour and 7 microamperes, a significant improvement of 10 minutes was achieved.
In the first embodiment of the present invention described above, the exposure cycles 21 and 21a are calculated for each scanning of the charged particle beam 10, but the optimum exposure cycles 21 and 21a are calculated from the beam current data and the resist sensitivity data before drawing. In addition to the method of calculating and setting, and the method of calculating the exposure exposure cycles 21 and 21a for each deflection area of the deflector, the method of calculating and setting the optimum exposure cycles 21 and 21a for each predetermined exposure area may be used. Similar effects can be achieved.

Next, a charged particle beam exposure apparatus according to a second embodiment of the present invention will be described with reference to FIG.
In the first embodiment of the present invention, the method for determining the exposure time and the exposure cycles 21 and 21a based on the beam current and the resist sensitivity has been described. In the second embodiment, a method that further considers the influence of proximity effect correction will be described.
FIG. 4 shows a circuit for setting an optimum clock for explaining the second embodiment.
The required exposure time is calculated from the bitmap data transferred from the bitmap conversion circuit 15, the preset resist sensitivity data 23, the preset or measured beam current data 22, and the proximity effect correction data 25 calculated in advance. 24. The calculation of the exposure time can also be performed based on at least one of the beam current of the charged particle beam, the resist sensitivity, and the proximity correction value. When the exposure time is calculated, the optimum exposure cycles 21 and 21a based on the exposure time are calculated by the optimum exposure cycle calculation 25 and transferred to the individual blanking control circuit 17.
The series of operations described above are performed for each scanning of the beam, and the exposure cycles 21 and 21a are calculated and optimized. The exposure amount of each pixel in one scan is increased or decreased by proximity effect correction, but the exposure cycle is defined by the maximum exposure amount in one scan. At the same time, when the exposure cycles 21 and 21a change, the beam scanning time also changes, so that the data is also sent to the deflection signal generation circuit 18.
When the proximity effect correction drawing was performed using the multi-electron beam exposure apparatus having the above configuration, the drawing time required 1 hour in both cases of the total beam current of 1 microampere and 7 microamperes, and the beam current of 1 microampere. In the case of, 1 hour was achieved, and in the case of 7 microamperes, it was 9 minutes.
In the above description, the exposure cycles 21 and 21a are calculated for each beam scan. However, the optimum exposure cycles 21 and 21a for each scan are calculated from the beam current data, resist sensitivity data, and proximity effect correction data before drawing. In addition to the method of calculating and setting the optimum exposure cycles 21 and 21a for each deflection area of the deflector, the method of calculating and setting the optimum exposure cycles 21 and 21a for each predetermined exposure area may be used. The same effect can be obtained by preparing data and storage areas according to the method.
Further, not only the proximity effect correction but also the exposure effect correction data can be applied to the optimum exposure cycle calculation 25 in the same manner, and the same effect as in the second embodiment can be obtained.

Next, as Example 3 of the present invention, a semiconductor device manufacturing process using the charged particle beam exposure apparatus according to Example 1 will be described.
FIG. 5 is a diagram showing a flow of an entire manufacturing process of a semiconductor device. In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (EB data conversion), exposure control data for the exposure apparatus is created based on the designed circuit pattern.
On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer using lithography using the exposure apparatus and wafer to which the exposure control data has been input. The next step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer produced in step 4, and is an assembly process (dicing, bonding), packaging process (chip encapsulation), etc. Process. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. A semiconductor device is completed through these processes, and is shipped in Step 7.
The wafer process in step 4 includes the following steps. An oxidation step for oxidizing the surface of the wafer, a CVD step for forming an insulating film on the wafer surface, an electrode formation step for forming electrodes on the wafer by vapor deposition, an ion implantation step for implanting ions on the wafer, and applying a photosensitive agent to the wafer The resist processing step, the exposure step for printing and exposing the circuit pattern onto the wafer after the resist processing step by the above-described exposure apparatus, the development step for developing the wafer exposed in the exposure step, and the etching for removing portions other than the resist image developed in the development step Step, resist stripping step to remove resist that is no longer needed after etching. By repeating these steps, multiple circuit patterns are formed on the wafer.

It is a principal part schematic block diagram of the charged particle beam exposure apparatus of a prior art example and Example 1 of this invention. It is explanatory drawing of operation | movement of the blanking array which comprises the charged particle beam exposure apparatus of the prior art example and Example 1 of this invention. It is explanatory drawing of the flow of exposure time of the charged particle beam exposure apparatus of Example 1 of this invention, and exposure cycle calculation. It is explanatory drawing of the flow of exposure time of the charged particle beam exposure apparatus of Example 2 of this invention, and an exposure cycle calculation. It is a figure which shows the flow of the whole manufacturing process of the semiconductor device using the charged particle beam exposure apparatus of Example 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electron source 2 Collimator lens 3 Mask 4 Lens array 5 Deflector 6 Blanking array 7, 8 Lens 9 Blanking stop 10 Charged particle beam 11 Sample 12 Controller 13 Lens control circuit 14 Drawing pattern generation circuit 15 Bitmap conversion circuit 16 Exposure Time control circuit 17 Blanking control circuit 18 Deflection signal generation circuit 19 Deflection amplifier 20 Exposure time 21, 21a Exposure cycle 22 Beam current data 23 Resist sensitivity data 24 Exposure time calculation 25 Optimal exposure cycle calculation 26 Proximity effect corrected exposure amount map

Claims (4)

A charged particle beam exposure apparatus for performing exposure by irradiating a sample coated with a resist with a beam from a charged particle source,
And blanking means for said deflecting the beam to control the irradiation onto the sample in the beam,
A deflector that deflects the beam and scans the beam over the sample;
Said blanking means and the deflector operates at an exposure cycle time and the beam the beam is irradiated onto the sample is represented by the sum of time that is not irradiated onto the sample,
In the exposure cycle, the time during which the beam is irradiated onto the sample is obtained from beam current data, resist sensitivity data, and proximity effect correction data, and the time during which the beam is not irradiated onto the sample is reduced according to the result. As described above, the charged particle beam exposure apparatus is variably set. Time during which the beam is irradiated onto the sample, wherein wherein said beam is determined from the maximum and becomes the exposure amount of the exposure amount increased or decreased by the proximity effect correction in one scan to the area on the sample Item 2. The charged particle beam exposure apparatus according to Item 1. 3. The charged particle beam exposure apparatus according to claim 1, wherein the charged particle beam exposure apparatus is a multi-beam type in which a plurality of the beams irradiated on the sample are present. Device fabrication, characterized by comprising the step of performing any one exposure to the sample using a charged particle beam exposure device as claimed in claims 1 to 3, and a step of developing the sample which has been exposed, the Method.

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