JP5581022B2 - Charged particle beam drawing apparatus and charged particle beam drawing method - Google Patents

Description

  The present invention relates to a charged particle beam drawing apparatus and a charged particle beam drawing method.

  In recent years, with the high integration of semiconductor integrated circuits, LSI (Large Scale Integration) patterns tend to become finer and more complicated. The wavelength of deep ultraviolet light used for pattern transfer is 193 nm, whereas the size of the pattern to be transferred is shorter than the wavelength. Along with this demand for miniaturization, the complexity of lithography technology is accelerating. However, in order to produce LSIs in large quantities, the lithography technology that can transfer the pattern drawn on the original mask onto the wafer requires a degree of freedom to change the design of the mask pattern that differs from product to product. It is. For this reason, the pattern writing on the mask uses the electron beam lithography technique used by the electron beam writing apparatus as before.

  The electron beam lithography technique has an essentially excellent resolution because the electron beam used is a charged particle beam. Further, since a large depth of focus can be secured, there is an advantage that dimensional variation can be suppressed even on a high step. For this reason, the electron beam lithography technique is widely used also in the manufacturing site of a mask or a reticle that becomes an original when transferring an LSI pattern onto a wafer. Furthermore, an electron beam lithography apparatus that directly draws a pattern on a wafer using an electron beam lithography technique is applied to the development of state-of-the-art devices such as DRAMs, and is also used for the production of some ASICs. Yes.

  An electron beam lithography apparatus for realizing such an electron beam lithography technique usually includes a drawing chamber containing a stage on which a sample (mask substrate or wafer) to be drawn is placed, and a sample placed on the stage. And an electron column for irradiating an electron beam from an electron gun included in the above. The stage in the drawing chamber includes a guide and a stage driving motor as stage moving means for moving the stage. In addition, a deflector or the like is provided in the electron lens barrel, and the irradiation position of the electron beam on the sample is determined based on a deflection signal applied via a DAC (Digital to Analog Converter) amplifier using the deflector. It can be controlled.

  In such a drawing apparatus using an electron beam, a vacuum chamber in which a position measuring device for controlling a stage for holding a sample with respect to the position of the electron beam is fixed, an electron column mounted on the vacuum chamber, It is required to control the temperature of a DAC amplifier arranged near the electron column and the sample itself into which the electron beam is implanted. When the drawing operation is started, temperature fluctuations of the drawing apparatus caused by friction of the guide accompanying the operation of the stage, heat generation due to the electromotive force of the motor, heat generation of the DAC amplifier driven according to the pattern, etc. occur, The position of the electron beam measured with respect to the sample placed on the stage by the position measuring device may cause an error due to thermal expansion due to the heat generation, which affects the drawing accuracy. Therefore, also from such a viewpoint, suppression of the apparatus temperature rise and precise temperature maintenance control are required.

  Patent Document 1 discloses an exposure apparatus capable of adjusting the temperature and corresponding to high throughput. The disclosed exposure apparatus includes a fluid path through which a temperature-controlled fluid flows, a medium fluid flow path through which a medium fluid for cooling or heating the fluid, a heat exchanger that performs heat exchange between the fluid and the medium fluid, And a flow controller for controlling a flow rate of the medium fluid entering the heat exchanger.

FIG. 3 is a configuration diagram of a conventional electron beam drawing apparatus.
As shown in FIG. 3, an electron beam drawing apparatus 100 includes a drawing chamber 101 having a stage 103 on which a mask substrate 102 to be drawn is placed, and an electron gun provided for the mask substrate 102 placed on the stage 103. An electron barrel 120 that irradiates an electron beam from 130 and a drawing job in which drawing conditions are described based on the drawing data are created, and built in the stage 103 on which the mask substrate 102 is placed and the electron barrel 120 A drawing control computer 150 that controls the drawing operation on the mask substrate 102 by controlling the electron beam from the electron gun 130 is provided.
In creating a drawing job in the drawing control computer 150, first, desired drawing data is sent from the data server computer 160 to the data preprocessing computer 170 via the LAN. The sent drawing data is converted into data usable by the drawing control computer 150 by the data preprocessing computer 170. Then, it is sent to the drawing control computer 150 to create a drawing job.

  The drawing control computer 150 is connected to a machine control computer 140 that controls each part of the electron beam drawing apparatus 100 and DAC amplifiers 123 and 124 described later. The machine control computer 140 is connected to the drawing job described above. Control is performed by sending a deflection signal to the DAC amplifiers 123 and 124.

  In the drawing chamber 101 of the electron beam drawing apparatus 100, a stage 103 on which a mask substrate 102 as a sample is placed is provided. The stage 103 is installed on a guide 104 and can be driven in the X direction (left and right direction on the paper surface) and the Y direction (vertical direction on the paper surface) by a driving motor 106 controlled by a motor driver 105 as a controller. . The movement position of the stage 103 in the X and Y directions uses a laser mirror 116 provided on the stage 103, a laser head 107 as a laser light source, a laser interferometer 117, and a receiver 109 that receives laser light. It is measured by the XY position reading circuit 108.

The position control confirmation of the mask substrate 102 in the Z direction (vertical direction on the paper surface) uses a Z sensor light projecting unit 110 that emits laser light and a Z sensor light receiving unit 112 that receives the laser light provided in the upper part of the drawing chamber 101. This is made possible by the Z position reading circuit 111.
The operations of the motor driver 105, the XY position reading circuit 108, and the Z position reading circuit 111 can be controlled by a machine control computer 140 provided in the apparatus.

  An electronic lens barrel 120 is disposed on the ceiling of the drawing chamber 101. An electron beam optical system is installed inside the electron column 120. The optical system includes an electron gun 130 that emits an electron beam, deflectors 121 and 122, a beam shaping aperture (not shown), and the like. Then, in the deflectors 121 and 122 in the electron column 120, the electron beam on the mask substrate 102 is based on the deflection signal applied through the above-described DAC amplifiers 123 and 124 disposed on the apparatus. The irradiation position can be controlled.

  In the electron beam drawing apparatus 100, independent cooling water systems 181, 182, 183, and 184 are provided in the lower part of the guide 104 in the drawing chamber 101, the motor 106, and the DAC amplifiers 123 and 124, respectively. These cooling water systems 181, 182, 183, and 184 circulate the cooling water to each part to keep the temperature of each part constant, and as a result, the temperature of the entire electron beam drawing apparatus 100 is suppressed from rising. Yes.

JP 2005-142283 A

FIG. 4 is a flowchart for explaining a charged particle beam drawing method performed using a conventional electron beam drawing apparatus.
First, in step S1001, desired drawing data on a substrate to be drawn is registered in the data server computer 160. Next, this data is sent to the data preprocessing computer 170 and converted into data usable by the machine control computer 150, and then sent to the drawing control computer 150 to create a drawing job including drawing conditions and the like (S1002). .

  Based on the drawing job created in step S1002, the electron beam drawing apparatus 100 starts drawing (S1003). First, the mask substrate 102 which is a drawing target substrate is placed at a predetermined position in the apparatus 100, and the end of the drawing work related to the previous work is waited, or until the temperature in the mask substrate 102 and the apparatus 101 is stabilized. It waits for a necessary time (S1004).

Thereafter, in step S1005, the mask substrate 102 is transferred onto the stage 103, and the actual drawing operation is started (S1006). After confirming the state of the electron beam every set time (S1007), the drawing is finished (S1008). ).
If the next drawing operation is necessary, the mask substrate 102 is returned to step S1003 again to start drawing again. If such drawing work is not necessary, the drawing work is ended and the mask substrate 102 is transported for the next work (S1009).

  In each step from registration of the drawing layout data in step S1001 to conveyance of the mask substrate 102 to the next operation in S1009, as shown in FIG. 4, the temperature due to the cooling water circulation of the electron beam drawing apparatus 100 in step S1010. The stabilization work has been carried out independently. That is, the temperature of each part is controlled independently for each part of the electron beam lithography apparatus 100 for a predetermined set temperature, and control is performed so that the temperature of each part of the apparatus 100 always becomes a predetermined temperature independently of the progress of the drawing process. Has been made.

  However, when independent temperature control is performed in each part of the electron beam lithography apparatus 100 as described above, and further, the temperature control is performed independently of each process of the lithography work, the specific part such as the mask substrate 102 as a sample is used. When precise temperature control is required, it may not be able to respond sufficiently. In particular, since the temperature in the mask substrate 102 greatly affects the drawing accuracy, it is necessary to suppress the temperature rise even in a part of the mask substrate 102 and advance the drawing with the electron beam while the temperature of the sample is at a predetermined temperature. At present, temperature control cannot be performed with such accuracy.

  Recently, in order to improve the drawing accuracy in the electron beam lithography technique, it is necessary to increase the accuracy of electron beam control, and accordingly, the resolution of the DAC amplifiers 123 and 124 is being increased. On the other hand, when drawing a large and complicated mask pattern, the number of electron beam deflection positioning operations increases dramatically as the amount of data increases, leading to an increase in heat generation in the DAC amplifier itself. The importance of this cooling response will increase. In addition, it is technically difficult to increase the number of bits of the DAC amplifier as the resolution is increased. Therefore, if the number of bits to be controlled is not changed, the deflection width of the electron beam is inevitably narrowed, and a desired shape can be drawn. The number of stripes for the drawing area to be performed is increasing.

  Furthermore, the stage speed at the time of drawing is increased and the variable speed is increased for throughput improvement, and the stage speed can be changed even within one stripe according to the pattern density. On the other hand, in order to reduce shot noise of an electron beam, the sensitivity of a resist formed on a drawing target substrate is reduced. As a result, the travel distance on the stage of the drawing target substrate per drawing operation increases, for example, the number of passes increases, but the drawing time is shortened.

  However, if the drawing time per drawing operation is shortened, for example, the amount of heat generated per unit time on the mask substrate as a sample increases. Since the inside of the drawing chamber 101 of the electron beam drawing apparatus 100 and the electron column 120 disposed on the ceiling thereof is in a vacuum environment, heat generated inside the apparatus 100 such as on the mask substrate 102 is mainly transmitted to the structure. It is diffused and relaxed.

  As a result, a vacuum chamber (not shown) constituting the drawing chamber 101 may be deformed by expansion due to heat and the drawing chamber 101 may be deformed accordingly. If the installation site of the laser interferometer 109 that manages the position accuracy of the stage 103 is deformed, the position of the stage 103 may not be read accurately by the XY position reading circuit 108, and so-called drift may occur. is there.

  In order to prevent such a situation, naturally the cooling of the electron beam drawing apparatus 100, particularly the cooling of the DAC amplifiers 123 and 124, is effective. In the case of the conventional electron beam drawing apparatus 100 as shown in FIG. The temperature is stabilized by circulating the cooling water so as to keep the temperature of each part 100 constant, but as described later, the above-described drift cannot be sufficiently suppressed.

  Further, when paying attention to the structure of the stage 103 installed in the drawing chamber 101 in a vacuum environment, as a guide 104 to be used, an LM (Linear Motion) guide or a cross roller guide, which is conventionally made of a nonmagnetic material, etc. Has been used. The LM guide and the cross roller guide can be regulated by a relatively small frictional force by being guided by a ball or a roller.

  At this time, an LM guide having a large degree of freedom in structure is preferable in terms of the configuration of the electron beam drawing apparatus 100. However, since the resistance associated with the travel of the stage 103 is smaller in the cross roller guide, a highly accurate travel operation is longer. In an electron beam drawing apparatus that needs to continue for a time, a cross roller guide is preferred.

  However, even such a cross roller guide cannot completely suppress heat generation due to the resistance accompanying the travel of the stage 103. In addition, as described above, the apparatus performance is improved for throughput improvement, the stage speed at the time of drawing is increased and the variable speed is increased, and furthermore, when the travel distance on the stage of the drawing target substrate per drawing work increases, It is necessary to sufficiently control the heat generation.

  In particular, in the mask substrate 102 disposed on the stage 103 on the guide 104, heat is generated by the drawing operation by the electron beam as described above, and cooling is performed at the guide 104 portion disposed near the mask substrate 102. In addition, the temperature control is a very important function in the electron beam lithography apparatus 100 that requires precise temperature control in the vicinity of the mask substrate 102 as a sample.

  However, in the conventional electron beam drawing apparatus 100, for example, when the above-described DAC amplifiers 123 and 124 have risen in temperature more than a set value, the cooling operation is started by confirming this and further cooling water circulation. Usually there is a time lag before the effect appears. That is, a certain amount of time is required until each part of the apparatus 100 that has started to rise in temperature is actually cooled and returned to the set temperature state. As a result, deformation of the installation site of the laser interferometer 109 described above may occur, resulting in a situation where the position of the stage 103 cannot be read accurately.

  In order to suppress such deformation at the installation site of the laser interferometer 109, for example, the above-described temperature rise that occurs in the DAC amplifiers 123, 124, etc. can be predicted in advance, and the cooling start timing can be optimized. It is desirable to do so. However, such a function is not realized in the conventional electron beam drawing apparatus.

  Therefore, in an electron beam drawing apparatus, in order to achieve precise pattern adjustment and desired pattern dimensions and pattern accuracy, a conventional charged particle beam drawing apparatus such as an electron beam and a charged particle beam drawing using a conventional cooling method. The method is insufficient, and development of a new charged particle beam drawing apparatus and a new charged particle beam drawing method using the same is required.

  The present invention has been made in view of these points. That is, an object of the present invention is to provide a charged particle beam writing apparatus and a charged particle beam writing method capable of realizing a desired pattern dimension and pattern accuracy by enabling precise temperature adjustment.

  Other objects and advantages of the present invention will become apparent from the following description.

A first aspect of the present invention includes a drawing chamber in which a guide provided with a stage on which a sample is placed is arranged at the bottom, beam irradiation means for irradiating the sample with a charged particle beam, a stage according to predetermined drawing data, A charged particle beam drawing apparatus comprising a drawing control mechanism for controlling a beam irradiation means and irradiating a sample with a charged particle beam while drawing a predetermined pattern to draw a predetermined pattern;
At least a temperature control unit that controls the temperature in the vicinity of the guide,
The drawing control mechanism has a function of predicting in advance the temperature fluctuation with respect to the sample and guide time caused by charged particle beam irradiation from the drawing data, and starts the drawing of a predetermined pattern, and operates the temperature control unit according to the prediction. It is characterized by being configured to control the temperature in the vicinity of the guide.

In the first aspect of the present invention, the temperature control unit has a liquid cooling controller and a liquid cooling system disposed in the vicinity of the guide, and the cooling medium circulates in the liquid cooling system by the liquid cooling controller. It is configured as
The drawing control mechanism is preferably configured to control the temperature in the vicinity of the guide by operating the temperature control unit in accordance with the prediction and controlling the cooling capacity of the cooling medium circulating in the liquid cooling system.

In the first aspect of the present invention, on the upper part of the drawing chamber, a deflector for positioning the charged particle beam irradiated to the sample, a DAC amplifier for applying a deflection signal to the deflector under the control of the drawing control mechanism, And a motor for driving the stage is provided outside the drawing chamber.
The temperature control unit has a liquid cooling system disposed around the DAC amplifier and a liquid cooling system disposed around the motor, and a cooling medium circulates in each liquid cooling system by the liquid cooling controller. It is configured as
The drawing control mechanism is preferably configured to control the temperature of the DAC amplifier and the motor by operating the temperature control unit according to the prediction and controlling the cooling capacity of the cooling medium circulating in each liquid cooling system.

The second aspect of the present invention includes a step of placing a sample on a stage on a guide disposed at the bottom of the drawing chamber;
A step of predicting a temperature variation with respect to a time occurring at least in the vicinity of the guide from the drawing data, and creating a drawing job in which a drawing condition and a temperature control condition in the vicinity of the guide are determined based on the prediction and the drawing data;
Prior to drawing, transporting the sample onto the stage;
A step of drawing a predetermined pattern by irradiating a sample with a charged particle beam while moving the stage while performing temperature control near the guide from the start of drawing a predetermined pattern according to a drawing job. The present invention relates to a charged particle beam writing method.

  In the second aspect of the present invention, the step of creating the drawing job predicts the temperature fluctuation near the guide, and the temperature near the guide is started so that the temperature control is started before the temperature fluctuation near the guide occurs. Preferably, this is a step of creating a drawing job that defines the control conditions.

According to the first aspect of the present invention, a temperature fluctuation of each part of the apparatus such as a drawing room guide and a DAC amplifier caused by the charged particle beam irradiation is predicted from drawing data, and a drawing job corresponding to them is created. Based on this drawing job, the drawing operation control and the temperature control of each part of the constituting apparatus are realized under the optimum conditions during the drawing work.
Therefore, the electron beam drawing apparatus according to the first aspect of the present invention can perform precise temperature adjustment, and can realize desired pattern dimensions and pattern accuracy on the drawing target substrate.

According to the second aspect of the present invention, when drawing a drawing pattern from drawing data, for example, heat generated in the vicinity of a guide in the drawing room is predicted, and drawing is performed based on the prediction and the drawing data. And a drawing job that defines the temperature control conditions in the vicinity of the guide. In the step of controlling the stage and the beam irradiating unit based on a drawing job and irradiating the sample with a charged particle beam by the beam irradiating unit while moving the stage to draw a predetermined drawing pattern. Thus, drawing operation control and temperature control of each part of the apparatus configured under optimum conditions are realized in parallel.
Therefore, precise temperature adjustment is possible, and desired pattern dimensions and pattern accuracy on the drawing target substrate can be realized.

It is a block diagram of the electron beam drawing apparatus of this Embodiment. It is a flowchart explaining the electron beam drawing method of this Embodiment. It is a block diagram of the conventional charged particle beam drawing apparatus. It is a flowchart explaining the conventional charged particle beam drawing method.

  FIG. 1 is a configuration diagram of an electron beam drawing apparatus which is an example of a charged particle beam drawing apparatus according to the present embodiment.

  The electron beam drawing apparatus 1 shown in FIG. 1 is an apparatus that can be installed in a clean room. The electron beam drawing apparatus 1 includes a drawing chamber 51 that includes a stage 3 on which a mask substrate 2 that is a sample to be drawn is placed and is evacuated. An electron lens barrel 20 is provided as beam irradiation means for irradiating the mask substrate 2 placed on the stage 3 from the electron gun 30 with an electron beam which is an example of a charged particle beam. Further, a drawing job describing drawing conditions and the like is created. Based on this, a drawing job is controlled by controlling an electron beam from the stage 3 on which the mask substrate 2 is placed and the electron gun 30 built in the electron lens barrel 20. A drawing control computer 50 is provided as a drawing control mechanism for controlling the drawing work on the mask substrate 2 in 51.

  For obtaining drawing data and creating a drawing job in the drawing control computer 50, first, desired drawing data is registered in the data server computer 60. Then, the data is transmitted from the data server computer 60 to the data preprocessing computer 70 included in the apparatus 1 via the LAN. Then, the transmitted drawing data is converted into data in a format usable by the drawing control computer 50 by the data preprocessing computer 70, and then sent to the drawing control computer 50 for acquisition. Then, a drawing job including drawing conditions and the like is created according to the drawing data.

  The drawing control computer 50 is connected to a machine control computer 40 and DAC amplifiers 23 and 24, which will be described later, for controlling the machine operation of each part of the apparatus, and controls the machine control computer 40 based on this drawing job. The DAC amplifiers 23 and 24 are controlled by sending deflection signals.

  In the drawing chamber 51 of the electron beam drawing apparatus 1, a stage 3 on which a mask substrate 2 as a sample is placed is provided. The mask substrate 2 is placed on the stage 3 through a plurality of (for example, three) support members 15 that are erected. The stage 3 is installed on the guide 4 and can be driven in the X direction (left-right direction on the paper surface) and Y direction (vertical direction on the paper surface) by a driving motor 6 controlled by a motor driver 5 which is a controller. .

  A laser mirror 16 is fixed to the end of the stage 3, and further includes a laser head 7 that is a laser light source, a receiver 9 that receives laser light, and a laser interferometer 17. It constitutes a long system. The laser light emitted from the laser head 7 is branched by the laser interferometer 17 and part of the laser light is incident on the laser mirror 16 disposed on the stage 3, and the rest is mounted near the lens barrel (not shown). It is incident on the reference mirror placed. The laser light reflected by the laser mirror 16 and the reference mirror is caused to interfere again via the laser interferometer 17, whereby interference light is obtained and further received by the receiver 9. The receiver 9 converts the frequency change of the light into an electric signal and outputs it to the XY position reading circuit 8, and the position of the stage 3 in the X and Y directions is measured by this output.

  The position of the mask substrate 2 in the Z direction (vertical direction in the drawing) is such that the Z sensor light projecting unit 10 that emits laser light toward the mask substrate 2 provided on the drawing chamber 51 ceiling, and the mask substrate 2. An optical lever-type Z sensor constituted by a Z sensor light receiving unit 12 that receives the laser beam reflected by the laser beam is used, and the position of the stage 3 in the Z direction is output from the Z sensor light receiving unit 12 to the Z position reading circuit 11. Can be measured.

  The operations of the motor driver 5, the XY position reading circuit 8, and the Z position reading circuit 11 can be controlled by a machine control computer 40 to which each is connected.

  At this time, as the guide 4 for installing the stage 3, a cross roller guide having a small resistance accompanying the travel of the stage 3 is employed. The cross roller guide is a guide system composed of a roller race having a V groove and a cylindrical roller. In the electron beam drawing apparatus 1 that needs to continue a highly accurate traveling operation for a long time, it is preferable to use a cross roller guide as compared with an LM guide or the like.

  However, even with such a cross roller guide, heat generation cannot be completely suppressed due to resistance associated with traveling. In addition, as described above, the stage speed at the time of drawing is increased and the variable speed is increased to improve the throughput, and furthermore, the travel distance on the stage of the drawing target substrate per drawing work is increased, so that drawing is in progress. Sufficient control over heat generation is required.

  In addition, an air bearing using a differential exhaust with a small guide resistance accompanying the movement of the stage has been proposed. This regulates the degree of freedom of the stage, which has been regulated by a ball or a roller, by compressed air. However, in order to realize differential exhaust, it is necessary to operate the pump at all times, the device design load accompanying intake / exhaust is large, and the temperature of the air to be floated needs to be controlled to be constant. For example, the structure for guiding the stage in vacuum is considered to be more restrictive than the above-described cross roller guide.

  Therefore, although the use of the cross roller guide is preferable as described above, the mask substrate 2 disposed on the stage 3 on the guide 4 generates heat due to the drawing work by the electron beam as described above, and thus needs to be improved. Become. That is, such cooling and temperature control in the guide 4 portion arranged near the mask substrate 2 is very important in the electron beam lithography apparatus 1 that requires precise temperature control in the vicinity of the mask substrate 2 as a sample. Requirements.

  Therefore, in the electron beam drawing apparatus 1 of the present embodiment, a liquid cooling system 72 capable of circulating a cooling medium is provided as temperature control means at the bottom of the drawing chamber 51 where the guide 4 is disposed. .

  Further, the stage 3 is installed on the guide 4 and can be driven in the X direction and the Y direction by the driving motor 6 controlled by the motor driver 5. As described above, the drawing target substrate per drawing operation Since the on-stage travel distance has increased, the amount of heat generated in the stage driving motor 6 has increased. The heat generated in the motor 6 affects the laser interferometer 17 through the wall of the drawing chamber 51 and hinders accurate length measurement. Therefore, sufficient suppression and control are required. Therefore, in the electron beam drawing apparatus 1 of the present embodiment, a liquid cooling system 73 capable of circulating a cooling medium is provided as a temperature control means for the motor 6 that drives the stage 3 on the guide 4. .

  On the ceiling of the drawing chamber 51, an electron lens barrel 20 as a beam irradiation means is erected. An electron beam optical system is installed inside the electron column 20. This optical system includes an electron gun 30 that emits an electron beam, deflectors 21 and 22, a beam shaping aperture (not shown), and the like. Then, in the deflectors 21 and 22 in the electron column 20, the electron beam on the mask substrate 2 is based on the deflection signal applied via the above-described DAC amplifiers 23 and 24 disposed on the apparatus 1. The irradiation position can be controlled.

  At this time, in order to improve the drawing accuracy on the mask substrate 2, it is necessary to increase the accuracy of the electron beam control. In order to cope with this, the DAC amplifiers 23 and 24 achieve a higher resolution. On the other hand, when drawing a large-scale and complicated mask pattern, the number of electron beam deflection positioning operations increases dramatically as the amount of data increases, leading to an increase in heat generation in the DAC amplifiers 23 and 24 themselves. Therefore, liquid cooling systems 75 and 76 capable of circulating a cooling medium are provided for the DAC amplifiers 23 and 24 as temperature control means for cooling and maintaining the temperature constant.

  As described above, in the electron beam drawing apparatus 1, the liquid cooling systems 72, 73, 75, and 76 are provided in the bottom of the drawing room 51 under the guide 4, the motor 6, and the DAC amplifiers 23 and 24, respectively. It has been. These liquid cooling systems 72, 73, 75, and 76 are connected to a liquid cooling controller 55 provided in the electron beam drawing apparatus 1, and the cooling medium 55 circulates the cooling medium in the liquid cooling system. Control is made. That is, in the electron beam drawing apparatus according to the present embodiment, the temperature controller is configured by the liquid cooling controller 55 and the liquid cooling systems 72, 73, 75, and 76 connected thereto.

  The liquid cooling controller 55 can individually control each of the liquid cooling systems 72, 73, 75, and 76. In other words, each of the liquid cooling systems 72, 73, 75, 76 is configured to be able to selectively control the flow rate of the cooling medium to be circulated independently, and in the vicinity of the guide 4 in the drawing chamber 51, the motor 6, and the DAC amplifier. 23 and 24 are configured such that a desired temperature can be achieved independently of each other.

  As a cooling medium that can be used for each of the liquid cooling systems 72, 73, 75, and 76 provided in the electron beam drawing apparatus 1, water or some substance is used for the purpose of preventing deterioration of the apparatus parts and raising the boiling point. In addition, it is possible to use the aqueous solution produced. Further, it is possible to use a fluorine-based cooling medium such as HFE (hydrofluoroether). As another cooling medium, FC (Fluorinert) or HFPE (H-Galden) can be used.

  In this way, in the electron beam drawing apparatus 1 of the present embodiment, it is possible to perform independent temperature control and management according to each situation for each part such as the vicinity of the guide 4 that may generate heat. The liquid cooling controller 55 to be realized is connected to the machine control computer 40 and controlled based on temperature fluctuation prediction with respect to time, starting from drawing of a predetermined pattern. That is, the operation of the motor driver 5, the XY position reading circuit 8, and the Z position reading circuit 11 can be controlled by the machine control computer 40 connected thereto.

  At this time, the machine control computer 40, together with the DAC amplifiers 23 and 24, is configured to be controlled by the drawing control computer 50 based on the drawing job described above. Therefore, in the electron beam drawing apparatus 1 of the present embodiment, it is possible to control the operation of the DAC amplifiers 23 and 24 and the drawing work in the drawing room 51 according to the drawing job, but in parallel with these controls. Thus, starting from the start of drawing a predetermined pattern, the liquid cooling controller 55 is controlled by the machine control computer 40 based on the temperature fluctuation prediction with respect to time, and the heat generated in each part of the apparatus can be controlled individually and at optimum timing. Is possible.

  With the above configuration, the electron beam drawing apparatus 1 according to the present embodiment can perform precise temperature adjustment, and can achieve desired pattern dimensions and pattern accuracy on the drawing target substrate.

  Note that, with respect to a drawing job created by the drawing control computer 50 of the electron beam drawing apparatus 1 according to the present embodiment and describing drawing conditions and the like, the pattern is generated in the electron beam drawing apparatus 1 from the start of drawing a predetermined pattern. The heat generated according to the density is quickly absorbed by realizing the necessary and sufficient heat capacity based on the temperature fluctuation prediction with respect to time by the liquid cooling systems 72, 73, 75, 76 arranged in the vicinity of the heat generating part. Therefore, it is possible to maintain the temperature at a constant temperature. In that case, if the maintenance and improvement of the position measurement accuracy in the laser length measurement system using the laser interferometer 17 is taken into consideration, it is very important to reduce the temperature fluctuation generated in each part of the apparatus.

  That is, it is possible to change the heat capacity of the refrigerant in response to temperature fluctuations different for each drawing pattern, from the conventional method for maintaining a preset temperature with respect to the temperature rise generated in each part of the electron beam drawing apparatus 1. More preferably, a possible drawing job is created. Specifically, based on information such as a drawing pattern and a drawing order in drawing data, electron beam drawing such as the vicinity of the guide 4 in the drawing chamber 51 and the DAC amplifiers 23 and 24 and the motor 6 when the drawing start of the pattern is started. The liquid cooling systems 72, 73, 75, and 76 are predicted so as to start appropriate cooling from the stage before the actual temperature fluctuation occurs so as to predict the temperature rise in each part of the apparatus 1 and to obtain a necessary and sufficient heat capacity. It is preferable to create a drawing job that enables execution of the temperature control used.

If drawing work is performed in the electron beam drawing apparatus 1 according to such a drawing job, it is possible to suppress the occurrence of temperature rise in each part of the apparatus, which is expected to vary depending on the pattern and drawing order, It is possible to maintain and improve position measurement accuracy in a laser length measurement system using the laser interferometer 17.

  As described above, in the electron beam drawing apparatus 1 according to the present embodiment, the drawing operation control and the temperature control of each part of the constituting apparatus are realized under optimum conditions based on the drawing job. Therefore, by using the electron beam drawing apparatus 1 according to the present embodiment, it is possible to realize a novel electron beam drawing method that has not existed before. This new drawing method achieves the desired pattern dimensions and pattern accuracy, and also can efficiently reduce the heat generated even when the stage on which the mask substrate is placed travels at high speed, resulting in high throughput. Is possible.

FIG. 2 is a flowchart for explaining the electron beam drawing method of the present embodiment.
First, in step S101, a drawing layout drawn on the mask substrate 2 as a drawing target sample is registered in the data server computer 60 as drawing data. At this time, the data server computer 60 analyzes the registered drawing data, recognizes the drawing pattern density, the pattern arrangement, the required electron beam shot density (multiplicity of shots), and the drawing order. get.

  Then, based on the data obtained in this way, a change in the required irradiation amount of the electron beam and a heat generation amount associated with the travel of the stage 3 on which the mask substrate 2 is placed are predicted, and at the same time, the mask substrate 2 starts from the drawing start. Further, the temperature distribution generation site, temperature distribution profile, temperature distribution generation time, etc. on stage 3 are predicted. Furthermore, the generation time and level of heat generation in the vicinity of the guide 4 accompanying the traveling operation of the stage on which the mask substrate 2 is placed from the start of drawing, the generation time and magnitude of the heat generation in the motor 6 that drives the stage 3, Further, the time and magnitude of heat generation in the DAC amplifiers 23 and 24 based on the drawing pattern density are predicted, and obtained as temperature change prediction data with respect to the elapsed time.

  For example, for the DAC amplifiers 23 and 24, as the drawing pattern density increases, the load for positioning the drawing of the electron beam increases, and the heat generation amount of the DAC amplifiers 23 and 24 increases. Accordingly, the heat generation of the DAC amplifiers 23 and 24 is predicted from the drawing data starting from the drawing start, and the DAC amplifiers 23 and 24 that have generated heat can be efficiently cooled as time passes. It is effective to convert information for circulating the cooling medium set to an appropriate temperature at an appropriate flow rate for an appropriate time into data at the stage of obtaining temperature change prediction data.

  Further, depending on the drawing pattern density and pattern arrangement, the travel distance and speed of the stage 3 on which the mask substrate 2 is placed may increase. In such a case, heat generated by the motor 6 or the guide 4 The amount of heat generated near the guide 4 due to the resistance increases. In order to efficiently cool the vicinity of the motor 6 and the guide 4 that have generated heat starting from the start of drawing, a cooling medium set to an appropriate temperature according to the passage of time is circulated at an appropriate flow rate for an appropriate time. It is effective to convert the information for this into data at the stage of obtaining temperature change prediction data.

  Further, the drawing pattern on the mask substrate 2 is usually not uniform, and the pattern density is generally sparse and dense in the drawing pattern. Further, the pattern may be a single piece of data, or it may be composed of a plurality of chips. The travel distance and speed of the stage 3 change according to the pattern density distribution on the mask substrate 2 and the drawing order in the case of a pattern composed of a plurality of chips. That is, when the pattern density is dense, the travel distance and speed of the stage 3 are reduced, and when the pattern density is sparse, the travel distance and speed of the stage 3 are increased. As a result, a heat generation distribution is generated depending on the stage position, and a temperature distribution is generated on the mask substrate 2 and the stage 3.

  For the mask substrate 2 and the stage 3 in which such a temperature distribution has occurred, it may not be effective to simply circulate a cooling medium for keeping the temperature constant. That is, the stage 3 whose trajectory is regulated by the cross roller guide is composed of a portion fixed to the bottom of the drawing chamber and an operating portion on which the mask substrate 2 can be placed, and if the heat capacity of the cooling medium is sufficient Even if there is a temperature fluctuation, it is possible to suppress the fluctuation to a certain temperature or less. However, in order to sufficiently secure the heat capacity of the cooling medium, a very large flow rate is required because the temperature change is small. On the other hand, when it is intended to cool the periphery of the mask substrate 2 and the stage 3 with a cooling medium set to a temperature lower than usual in order to efficiently control the temperature, the temperature is originally increased in a region where there has been no significant temperature increase. A situation occurs that falls too much. In such a case, since it is effective to circulate the cooling medium set to a desired temperature at a higher flow rate, information is converted into data at the stage of temperature change prediction data acquisition so as to adopt such a method. It is effective to keep it.

  Furthermore, in the electron beam drawing method of the present embodiment, the heat generated in the electron beam drawing apparatus 1 to be used is kept at a constant temperature by the liquid cooling systems 72, 73, 75, 76 disposed in the vicinity of the heat generating portion. Thus, the temperature of each part of the apparatus is controlled. As a result, it is possible to maintain the temperature of each part of the electron beam drawing apparatus 1 at a constant temperature. However, if the maintenance and improvement of the position measurement accuracy in the laser measurement system using the laser interferometer 17 is taken into consideration, the apparatus It is also important to more actively reduce temperature fluctuations occurring in each part.

  That is, the temperature rise generated in each part of the apparatus 1 is detected by detecting the temperature change of the liquid cooling system that maintains the temperature of the target location, and tries to respond by controlling the refrigerant so that the temperature becomes constant. A method for suppressing temperature fluctuation itself is more preferable than the conventional method. Specifically, the temperature rise starting from the drawing start in each part of the electron beam drawing apparatus 1 is predicted in advance from information such as the drawing pattern and drawing order in the drawing data, and such a situation occurs before the temperature fluctuation actually occurs. In preparation for this, a method of starting temperature control is more preferable. Therefore, it is desirable that such information is converted into data at the stage of temperature change prediction data acquisition so that a method of suppressing the occurrence of temperature rise in each part of the apparatus itself can be taken.

  Next, the drawing data and the temperature change prediction data as described above are sent to the data preprocessing computer 70 and converted into data usable by the machine control computer 40. Thereafter, the data is sent to the drawing control computer 50, and a drawing job corresponding to the drawing conditions and the above-described temperature change prediction data is created (S102).

  The machine control computer 40 and the DAC amplifiers 23 and 24 are controlled according to the created drawing job. Then, the machine control computer 40 controls the operation of the stage 3 on which the mask substrate 2 in the drawing chamber 51 is placed and the operation of the electron gun 30 built in the electron lens barrel 20, so that the electrons to the mask substrate 2 are controlled. Beam drawing work is executed. When the drawing starts, the liquid cooling controller 55 is controlled by the machine control computer 40, and the temperatures in the vicinity of the DAC amplifiers 23, 24, the motor 6, and the guide 4 using the liquid cooling systems 72, 73, 75, 76 are used. Control is executed.

  That is, in the drawing job, the temperature distribution on the mask substrate 2 and the stage 3 generated according to the elapsed time during the drawing operation in the drawing chamber 51 is eliminated, and it is possible to always maintain the desired temperature. Thus, for each of the liquid cooling systems 72 and 73, the temperature and flow rate of the cooling medium to be circulated for each time are set in advance. In addition, each of the liquid cooling systems 72, 73, 75, and 76 is configured so that heat generation in the vicinity of the guide 4, the DAC amplifiers 23 and 24, and the motor 6 can be efficiently suppressed and always maintained at a desired temperature. The temperature and flow rate of the cooling medium to be circulated for each time are set in advance.

  In accordance with the drawing job created in step S102, in the electron beam drawing apparatus 1, the drawing control computer 50 controls the machine control computer 40, the DAC amplifiers 23 and 24, etc., and the stage on which the mask substrate 2 in the drawing chamber 51 is placed. 3 and the operation of the electron gun 30 built in the electron lens barrel 20 are controlled, and the drawing work on the mask substrate 2 starts (S103). At the start of drawing, temperature control by the machine control computer 40 controlled by the drawing control computer 50 is started, the liquid cooling controller 55 is operated, the DAC amplifiers 23 and 24, the motor 6, and the vicinity of the guide 4, etc. Temperature control is started so that each part of the electron beam drawing apparatus 1 is maintained at a constant temperature. (S120).

First, the mask substrate 2 that is a drawing target substrate is placed at a predetermined position in the electron beam drawing apparatus 1, and the end of the previous drawing work is waited, or until the temperature in the mask substrate 102 and the apparatus is stabilized. Wait for a required time (S104).
Thereafter, the mask substrate 2 is transported onto the stage 3 in step S105.

  In step S106, it is confirmed whether or not the mask substrate 2 has reached the set temperature. If the mask substrate 2 temperature does not reach the set temperature, the drawing operation is stopped and started, and the liquid cooling controller 55 is operated to wait until the mask substrate 2 reaches the set temperature (S107). ). Thereafter, after the mask substrate 2 reaches the set temperature, a specific drawing operation is started under temperature control according to the drawing job by the drawing control computer 50 (S108).

  Then, according to the drawing job, based on the drawing pattern, the liquid cooling controller 55 operates in accordance with a target temperature determined for each predetermined time, and the liquid cooling systems 72, 73, 75, 76 are cooled under optimum conditions. Media circulation is performed. In addition, a predetermined desired temperature environment is set in each part of the apparatus such as the stage 3 and the stage 4 of the electron beam drawing apparatus 1, the mask substrate 2, the motor 6, and the DAC amplifiers 23 and 24. The state of the electron beam is checked every time (S109).

Then, a predetermined drawing pattern is drawn, and drawing is ended (S110).
If the next drawing operation is necessary, the mask substrate 2 is returned again to step S103, and drawing is started again. If not, the mask substrate 2 is transferred to the next operation (S111).

  In step S109, in parallel with the confirmation of the state of the electron beam with the set time, temperature control of each part of the apparatus such as the stage 3 and guide 4 of the electron beam drawing apparatus 1 and the mask substrate 2 is performed. Has been made. In that case, as described above, the temperature setting in each part of the electron beam drawing apparatus 1 is predicted in advance from the drawing pattern in the drawing data, and the temperature setting is set in preparation for such a situation before the temperature fluctuation actually occurs in the drawing job. It is effective to keep That is, it is effective to control the feed forward.

  For example, a drawing job is created by predicting heat generated in the DAC amplifiers 23 and 24, around the guide 4 and the motor 6 in advance, and cooling to them is started slightly before the actual temperature rise occurs. It is preferable to suppress the increase itself.

  If the temperature increase of each part of the electron beam drawing apparatus 1 can be suppressed by executing such a drawing job, it is possible to suppress the formation of a large temperature distribution on the stage 3 or the mask substrate 2 and the occurrence of the temperature distribution itself. Therefore, position reading using a laser length measurement system can be performed with higher accuracy. As a result, desired pattern dimensions and pattern accuracy can be realized in the electron beam writing method. Furthermore, even if the stage on which the mask substrate is placed is moved at high speed, the generated heat can be efficiently mitigated, and high throughput can be dealt with.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, an example of drawing on a mask substrate has been described, but the present invention can also be applied to drawing on a wafer. In the above embodiment, an electron beam is used. However, the present invention is not limited to this, and the present invention can also be applied to cases where other charged particle beams such as an ion beam are used.

DESCRIPTION OF SYMBOLS 1,100 Electron beam drawing apparatus 2,102 Mask substrate 3, 103 Stage 4, 104 Guide 5, 105 Motor driver 6, 106 Motor 7, 107 Laser head 8, 108 XY position reading circuit 9, 109 Receiver 10, 110 Z sensor Projection unit 11, 111 Z position reading circuit 12, 112 Z sensor light receiving unit 15 Support member 16, 116 Laser mirror 17, 117 Laser interferometer 20, 120 Electronic column 21, 22, 121, 122 Deflector 23, 24, 123, 124 DAC amplifier 30, 130 Electron gun 40, 140 Machine control computer 50, 150 Drawing control computer 51, 101 Drawing room 55 Liquid cooling controller 60, 160 Data server computer 70, 170 Data preprocessing computer 72, 73, 75 76, 81,182,183,184 liquid cooling system

Claims (5)

A drawing chamber constituting a vacuum chamber in which a guide provided with a stage on which a sample is placed is arranged at the bottom, beam irradiation means for irradiating the sample with a charged particle beam, the stage and the beam according to predetermined drawing data A charged particle beam drawing apparatus comprising: a drawing control mechanism for controlling the irradiation means and irradiating the sample with a charged particle beam while moving the stage to draw a predetermined pattern;
A temperature control unit that controls the temperature of at least the bottom where the guide is disposed ;
The drawing control mechanism has a function of said sample and said guide resulting from said charged particle beam emitted from the drawing data to predict the temperature variation with respect to time of the bottom is disposed, starting from the drawing start of the predetermined pattern In addition, the charged particle beam drawing apparatus is configured to control the temperature of the bottom portion where the guide is disposed by operating the temperature control unit according to the prediction. The temperature control unit has a liquid cooling controller and a liquid cooling system disposed at a bottom where the guide is disposed , and a cooling medium circulates in the liquid cooling system by the liquid cooling controller. It is configured as
The drawing control mechanism is configured to operate the temperature control unit according to the prediction, control a cooling capacity of a cooling medium circulating in the liquid cooling system, and control a temperature of a bottom portion where the guide is disposed. The charged particle beam drawing apparatus according to claim 1, wherein In the upper part of the drawing chamber, a deflector for irradiating and positioning the charged particle beam applied to the sample, and a DAC amplifier for applying a deflection signal to the deflector under the control of the drawing control mechanism are disposed. A motor for driving the stage is disposed outside the drawing chamber,
The temperature control unit includes a liquid cooling system disposed around the DAC amplifier and a liquid cooling system disposed around the motor, and the liquid cooling controller is used to control each of the liquid cooling systems. The cooling medium is configured to circulate,
The drawing control mechanism is configured to control the temperature of the DAC amplifier and the motor by operating the temperature control unit according to the prediction and controlling the cooling capacity of the cooling medium circulating in each liquid cooling system. The charged particle beam drawing apparatus according to claim 1 or 2, wherein Placing the sample on the stage on the guide located at the bottom below the drawing chamber;
A temperature variation with respect to time generated at least at the bottom portion where the guide is disposed is predicted from the drawing data, and a drawing condition and a temperature control condition of the bottom portion where the guide is disposed based on the prediction and the drawing data. Creating a drawing job that defines
Prior to the drawing, transporting the sample onto the stage;
According to the drawing job, a predetermined pattern is drawn by irradiating the sample with a charged particle beam while moving the stage while controlling the temperature of the bottom portion where the guide is arranged from the start of drawing a predetermined pattern. And a charged particle beam drawing method comprising: The step of creating the drawing job predicts the temperature fluctuation at the bottom where the guide is disposed, so that temperature control is started before the temperature fluctuation occurs at the bottom where the guide is disposed . The charged particle beam drawing method according to claim 4, wherein the drawing job is a step of creating a drawing job in which a temperature control condition of a bottom portion on which the guide is disposed is defined.

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