JP2002353116A - Charged particle beam lithographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charged particle beam lithographic apparatus that can accurately control temperature of the sample mount in the sample chamber, and further can measure the temperature difference between the sample and the sample mount for setting the temperature difference within a required range, as soon as to achieve superior drawing position accuracy, and to provide a drawing apparatus using the charged particle beam lithographic apparatus. SOLUTION: In this charged particle beam lithographic apparatus, having a sample mount 3 for retaining a sample 7, and stages 9 and 11 that mount the sample mount 3 and can be moved at least in one direction, an electric heater element and at least one temperature measuring instrument are provided on an upper surface opposite to the sample 7 on the sample mount 3, a heat conductive plate 40 is connected, and an apparatus 22 for cooling a base 13 is provided in a base 13 on the stage. In this case, the heat conductive plate 40 can be maintained at an arbitrary temperature by a temperature control apparatus for controlling the calorific value, in the electric heater element, based on the temperature measured by the temperature-measuring instrument.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a charged particle drawing apparatus.

[0002]

2. Description of the Related Art In recent years, demands for higher integration of semiconductor devices such as DRAMs have been increasing, and the pattern written on a photomask used for manufacturing these semiconductor devices has been rapidly becoming finer and more precise. I'm advancing. As a device for drawing such a fine pattern with high precision, a charged particle drawing device using an electron beam or the like is widely used, but various technical techniques are required to achieve the required finer and higher accuracy. Attempts have been made.

In particular, temperature management of a photomask to be written, temperature control of a sample chamber of a writing apparatus, temperature control of a sample stage on which a sample such as a photomask is mounted, and the like have recently become very important.

FIG. 14 is a diagram showing a configuration of a conventional charged particle drawing apparatus. An electron optical column 1 is installed in the sample chamber 2, and a sample stage for mounting a sample such as a photomask is installed inside the evacuated sample chamber 2.

The sample stage includes a sample table 3 on which a laser mirror 5 used for measuring the position of the stage, a sample holding means 6 for holding a sample 7 and the like, and a sample table supporting means 8 for supporting the sample table 3. A first stage 9, a guide device 10 of the first stage 9 for guiding the first stage 9 in a predetermined direction, and a second device connected to the guide device 10 and moving in a direction perpendicular to the first stage 9. It comprises a stage 11, a guide device 12 for a second stage 11 for guiding the stage 11, and a base 13 for holding the first stage 1 and the second stage. The stage 11 is fixed inside the sample chamber 2 by stage supporting means 14. ing.

[0006] The position of the sample stage is a laser mirror 5.
And an interferometer 4 attached to the sample chamber 2. This sample stage is firstly connected via the connecting device 15 by the driving device 16 controlled by the stage control device 32.
The stage 9 is moved, and the second stage is moved by a driving device (not shown) so that a pattern can be drawn on the entire sample 7.

In such a charged particle drawing apparatus, the sample chamber 2
When the sample chamber 2 is deformed due to temperature fluctuations in the environment where the sample is placed, an error occurs in the position measurement of the sample stage, and the positional accuracy of the pattern to be drawn deteriorates. Embedded, sample room constant temperature water controller 2
The constant-temperature water maintained at a constant temperature by 1 is circulated in the wall surface of the sample chamber so that the temperature change of the sample chamber 2 is minimized.

Although the temperature change of the sample chamber 2 can be suppressed by such a method, since the inside of the sample chamber 2 is in a vacuum state, it is impossible to control the temperature of the sample stage installed therein. It is. Further, since the first stage 9 and the second stage 11 move on the sample stage, heat generation due to frictional heat of the guide device 10 of the first stage 9 and the guide device 12 of the second stage 11 can be avoided. In addition, while performing frequent stage operations such as drawing operation, the temperature of the first stage 9 and the second stage 11 rises, and heat is conducted to the sample stage 3 installed thereon, so that the sample The temperature of the table 3 also rises. Due to this, the mounting position of the installed laser mirror 5 changes due to the thermal expansion of the sample table 3, and the position measurement accuracy of the stage deteriorates, or the sample 7 itself mounted on the sample table 3 becomes radiant heat of the sample table 3. As a result, the temperature rises, and thermal expansion of the sample 7 occurs, thereby deteriorating the positional accuracy of the pattern to be drawn.

For this reason, conventionally, an attempt has been made to prevent the temperature of the stage from rising by circulating constant-temperature water having a constant temperature through the base 13 of the sample stage in the sample chamber 2.
Since the material used for the stage structure has a low thermal conductivity, it is difficult to stabilize the temperature of the entire sample stage including the moving part, even though the temperature of the base part can be stabilized to some extent. It was also considered that a flexible constant temperature water pipe or a heat pipe was connected to the upper movable part from the sample stage base 13 to control the temperature of the entire stage. Most of them have not been put into practical use due to problems such as properties and deformation force. Even if the cooling water can be connected, it is difficult to control the temperature if the flow rate of the constant temperature water and the heat transfer area are not sufficient because the heat capacity of the entire stage is large. Apart from this, it has been considered to control the temperature by connecting an element having a heating and cooling function such as a Peltier element to an upper mechanism such as a movable part, but a large current is required to drive the Peltier element, At present, it is still difficult to put the device into practical use because the influence of the magnetic field fluctuation has a large effect on the electron beam and the like, and the use of cooling water or the like is also necessary for discharging the absorbed heat.

Further, when very high positional accuracy is required, the temperature of the sample 7 carried into the sample table 3 becomes a problem. If there is a difference between the temperature of the loaded sample 7 and the temperature of the sample table 3 located at the opposite position, heat is exchanged by radiation, and the temperature of the sample 7 gradually changes from the time of loading to the time of drawing. This causes a pattern position error. As a countermeasure, the temperature of the sample 7 is stabilized so as to be as equal as possible to the temperature of the sample table 3 before being carried into the stage. However, it is necessary to measure the temperature of the sample table 3 accurately. It was not easy due to problems such as an error with the temperature sensor when the temperature of the sample 7 was stabilized at another place. In addition, since it is difficult to accurately measure the temperature of the sample 7 in the state of being carried into the sample stage 3, it is impossible to draw after the temperature difference between the sample 7 and the sample stage 3 is sufficiently large. there were.

[0011]

In order to cope with higher accuracy required for a charged particle writing apparatus in the future, it is necessary to precisely control the temperature of a sample stage, especially a sample stage on which a sample is mounted. Conventionally, since the sample stage was set in a vacuum, the only option was to stabilize the temperature with constant temperature water that kept the temperature constant.However, due to the low thermal conductivity of the stage, sufficient temperature control was not possible. It was difficult to circulate constant temperature water through the movable stage. For this reason, it has not been possible to accurately control the temperature of the sample stage requiring the most precise temperature control.

Further, the difference between the temperature of the sample stage on which the sample is mounted and the temperature of the sample to be drawn cannot be measured accurately, and drawing cannot be performed after the temperature difference between the sample and the sample stage falls within a predetermined range. Met.

In the present invention, in order to realize a high writing position accuracy, the temperature of the sample stage portion of the sample stage in the sample chamber can be controlled with high accuracy, and the temperature difference between the sample and the sample stage is measured and the difference is measured. It is an object of the present invention to provide a charged particle drawing apparatus capable of drawing more quickly within a required range and a drawing method using the same.

[0014]

In order to achieve the above object, the present invention provides a sample chamber for introducing a sample and a sample chamber provided in the sample chamber so that the charged particles are irradiated on the sample surface. A sample stage capable of holding the sample, heat generating means provided on the sample stage, temperature measuring means for detecting the temperature of the sample, and at least one
A stage that allows the sample stage to move in a direction, a base that holds the stage, a cooling unit provided on the base, and a temperature controller that controls the heating unit based on the output of the temperature measurement unit. The charged particle drawing apparatus is provided, wherein heat generation by the heating means is stopped while the charged particles are irradiated on the sample.

At this time, it is preferable that the heat generating means is an electric heating device, and that the heat generation is controlled by controlling a supplied current by the temperature control device.

It is preferable that the heat generating means is provided on a heat conductive plate on the sample table, and the temperature measuring means is provided on the heat conductive plate.

Further, it is preferable that the heating means and the temperature measuring means are grounded while the charged particles are irradiated on the sample.

Further, it is preferable that a heating means and a temperature measuring means provided on the stage are provided.

Further, the temperature of the sample chamber and the temperature of the sample stage are made substantially equal to a predetermined temperature, the sample is introduced into the sample stage, and the temperature of the sample is measured by the temperature measuring means. If the temperature has deviated from the predetermined temperature beyond a predetermined temperature range, the heat generating means is caused to generate heat or is left to stand by until the temperature falls within the temperature range, and the temperature measuring means When the temperature falls within the temperature range, a drawing operation is started, and after drawing a predetermined drawing area, the temperature of the temperature measuring unit is measured, and the temperature is changed from the predetermined temperature to a predetermined temperature range. In the case where the temperature of the temperature measuring unit falls within the temperature range, the heating unit may generate heat or stand by until the temperature falls within the temperature range. It is preferable to move to draw the next drawing area.

Further, before drawing the sample, the temperature of the sample chamber and the temperature of the sample may be substantially matched, and the temperature of the base may be maintained lower than the temperature of the sample stage. preferable.

Before drawing the sample, the temperature of the sample chamber is made substantially equal to the temperature of the sample table, the temperature of the stage is set lower than the temperature of the sample table, and the temperature of the base is set at the same level. Preferably, the temperature is lower than the stage temperature.

[0022]

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

(First Embodiment) FIG. 1 is a configuration diagram showing a charged particle drawing apparatus according to a first embodiment of the present invention.

The configuration of the charged particle drawing apparatus of the present invention will be described with reference to FIG.

An electron optical column 1 is installed in the sample chamber 2, and a sample stage for mounting a sample such as a photomask is installed inside the evacuated sample chamber 2. The electron optical column 1 is controlled by a drawing control device 31 to control the irradiation of charged particles, and at the same time, moves a sample stage by a stage control device 32 to draw a pattern on the entire surface of the sample 7. This process is controlled by the overall control device 30 together with components not shown.

The sample stage comprises a sample stage 3 on which a laser mirror 5 used for measuring the position of the stage, a sample holding means 6 for holding a sample 7 and the like, and a sample stage supporting means 8 for supporting the sample stage 3 are provided. A first stage 9, a guide device 10 of the first stage 9 for guiding the first stage 9 in a predetermined direction, and connected to the guide device 10 of the first stage in a direction perpendicular to the first stage 9. It comprises a moving second stage 11, a guide device 12 for guiding the second stage 11, and a base 13 for holding the first stage 9 and the second stage 11. It is fixed by support means 14.

In the present embodiment, the sample stage is a stacked type stage of the first stage 9 and the second stage 11 which move in directions orthogonal to each other, but the first stage 9 is on the plane of the base 13. It is specified in advance that the effect of the present invention is not affected even by a single stage configuration movable in two directions.

The position of the sample stage is measured by the laser mirror 5 and the interferometer 4 attached to the sample chamber 2. The sample stage is moved by the driving device 16 controlled by the stage controller 32 via the connecting device 15 to move the first stage 9 and the driving device (not shown) to move the second stage 11. It is possible to draw a pattern on the whole.

In such a charged particle drawing apparatus, the sample chamber 2
When the sample chamber 2 is deformed due to temperature fluctuations in the environment where the sample is placed, an error occurs in the position measurement of the sample stage, and the positional accuracy of the pattern to be drawn deteriorates. Embedded, sample room constant temperature water controller 2
The constant-temperature water maintained at a constant temperature by 1 is circulated in the wall surface of the sample chamber so that the temperature change of the sample chamber 2 is minimized.

By such a method, the temperature change of the sample chamber 2 can be suppressed. However, since the inside of the sample chamber 2 is in a vacuum state, it is impossible to control the temperature of the sample stage provided therein with the constant temperature water pipe 20 provided in the sample chamber 2. Further, since the first stage 9 and the second stage 11 move on the sample stage, heat generation due to frictional heat of the guide device 10 of the first stage 9 and the guide device 12 of the second stage 11 can be avoided. While performing frequent stage operations such as drawing operation, the temperature of the first stage 9 and the second stage 11 rises, and heat is conducted to the sample stage 3 installed thereon, thereby The temperature of the table 3 also rises. Due to this, the mounting position of the installed laser mirror 5 changes due to the thermal expansion of the sample table 3, and the position measurement accuracy of the stage deteriorates, or the sample 7 itself mounted on the sample table 3 becomes radiant heat of the sample table 3. As a result, the temperature rises, and thermal expansion of the sample 7 occurs, thereby deteriorating the positional accuracy of the pattern to be drawn.

Therefore, in the present invention, a heat conductive plate 40 controlled by the stage temperature controller 41 and capable of generating heat is connected to a position of the sample stage 3 facing the sample 7. The stage constant temperature water control device 2 is provided on the lower surface of the base 13 of the sample stage.
4 is connected to a cooling plate 22 capable of absorbing heat with the constant temperature water supplied by 4.

The temperature of the heat conducting plate 40 can be set to an arbitrary temperature by the stage temperature control device 41. However, since the heat conducting plate 40 itself has no heat absorbing function, the sample stage to which the heat conducting plate 40 is connected is set. When the temperature of the peripheral portion such as 3 is higher than the temperature of the heat conductive plate 40, it is impossible to control the temperature of the heat conductive plate 40 to an arbitrary temperature. Then cooling plate 2
2 is connected to the base 13, the heat of the entire sample stage is successively absorbed by the cooling plate 22, and if the temperature of the sample stage 3 is always kept sufficiently lower than the temperature of the heat conductive plate 40, the heat conductive plate It becomes possible to control the temperature of 40 to an arbitrary temperature.

In this embodiment, the stage base 1
As a device for cooling 3, a cooling plate 2 for circulating constant temperature water
2 is connected to the base 13, but when a cooling plate that can be separated from the base 13 is used as a cooling device for the base 13, the entire sample stage is compared with a method in which constant temperature water is directly connected to the base 13. For example, when the cooling plate 22 is removed from the base 13 without removing the thermostatic water pipe from the sample chamber 2 for maintenance or the like, the airtightness of the pipe can be easily maintained, and the sample stage can be easily attached and detached. By being.

As an apparatus for cooling the base 13, a method of cooling the entire base 13 directly by incorporating a pipe for circulating constant-temperature water in the structure itself of the base 13 is also effective. In addition, the base 13 or the cooling plate 22 and the stage temperature control device 4
1 is also effective.

Next, the structure and operation of the heat conducting plate 40 will be described with reference to FIG.

FIG. 2 is a perspective view showing the sample stage 3 of the charged particle writing apparatus according to the first embodiment of the present invention.

The sample stage 3 is provided with a plurality of sample support means 6 for supporting the sample 7 in a state separated from the sample stage 3. A heat conductive plate 4 having an area equal to or larger than the projected area of the sample 7 is provided at a position facing the sample 7.
0 is fixed to the sample table 3. In this state, a temperature measuring device 50 such as a platinum resistance thermometer built in the heat conducting plate 40 is used.
The temperature of the heat conduction plate 40 is measured by a temperature reading device 53 such as a platinum thermometer included in the stage temperature control device 41, and the heat conduction plate is controlled by using a heating control device 52 such as a current amplifier so as to reach a predetermined temperature. Heating wire 5 built in 40
1 is energized to increase the temperature of the heat conduction plate 40 to maintain the temperature of the heat conduction plate 40 constant. At this time, the sample stage 3 is maintained at a temperature lower than the set temperature of the heat conduction plate 40 by the stage cooling plate (not shown) as described above. It becomes possible to lower the temperature of the forty.

Since the sample 7 mainly faces the heat conducting plate 40 in which the temperature is kept constant, the sample 7
Is changed so that the temperature becomes equal to the temperature of the heat conducting plate 40. That is, when the temperature of the sample 7 carried into the sample table 3 is higher than the temperature of the heat conductive plate 40, heat is transferred from the sample 7 to the heat conductive plate 40, and the temperature of the heat conductive plate 40 rises.
The temperature rise is detected by the temperature measuring device 50, and the heating wire 51 is generated by the heat conduction plate temperature control device 54 such as a temperature controller.
The current flowing through the sample 7 is reduced, and the heat transferred from the sample 7 is released to the sample table 3 below. Similarly, the temperature of the sample 7 is
When the temperature is lower than 0, since the heat is transferred from the heat conductive plate 40 to the sample 7, the temperature of the heat conductive plate 40 is decreased. While the temperature of 40 is maintained, heat is transferred to the sample 7 and the time required for the temperature of the sample 7 to become equal to the temperature of the heat conducting plate 40 is reduced.

Although the sample 7 is connected to the sample stage 3 by the sample support means 6, the contact area between the sample 7 and the sample support means 6 is extremely small, and heat transfer between the sample stage 3 and the sample stage 3 due to conduction is caused by heat conduction. This is sufficiently smaller than the radiation effect of the plate.

The heat conducting plate 40 is connected to the sample stage 3, but there is a gap in the contact surface, and the heat conduction with the sample stage 3 is not large. Therefore, it is sufficient to consider heat generation and cooling corresponding to the heat capacity of the heat conductive plate 40 itself. Therefore, if a high heat conductive material such as copper is used for the heat conductive plate, the heat generating wire can be directly adhered to the sample table 3. It is possible to control the temperature more responsively than when trying to control the temperature of the entire sample stage 3.

The temperature of the sample stage 3 itself is further stabilized by the radiation from the heat conducting plate 40 and the heat conduction at the contact point. Therefore, the position of the laser mirror 5 mounted on the sample stage 3 is adjusted. It is possible to prevent the displacement due to the thermal expansion of the sample stage 3 from deteriorating the writing position accuracy.

In the present embodiment, the temperature reading device 53 and the heat conduction plate temperature control device 54 included in the stage temperature control device 41 are configured independently of each other. Even if the configuration includes functions, the effects of the present invention are not affected at all.

In the present embodiment, the heating wire 51 coming out of the heat conducting plate 40 and the signal line of the temperature measuring device 50 are directly connected to the stage temperature control device 41. Of course, these signals are actually used. The wires and electric wires are led from the sample stage 3 to the atmosphere via a first stage 9, a second stage 11, and a base 13 shown in FIG. Needless to say, it is connected to.

Next, the details of the heating wire 51 and the temperature measuring device 50 incorporated in the heat conducting plate 40 will be described with reference to FIG.

FIG. 3 is a plan view, a partial sectional view, and a partially enlarged view showing the structure of the heat conducting plate.

A temperature measuring device 50 such as a platinum resistance temperature detector is generally installed near a central portion of the heat conducting plate 40 at a representative temperature. In addition to the platinum resistance temperature detector,
Thermistors, quartz oscillators, thermocouples and the like can also be used and are selected according to the required temperature control accuracy, and this type does not affect the effects of the present invention.

As the heating wire 51, a nichrome wire or the like is generally used, but a wire using a high-resistance metal such as tungsten can also be used. However,
Due to the nature of handling charged particles, it is necessary to select a wire having no magnetism so that the magnetic field does not fluctuate due to the movement of the stage.

In order to minimize the influence of the magnetic field generated around the heating wire 51 near the sample 7 by energizing the heating wire 51, as shown in an enlarged view of a portion A in FIG. Fold the heating wire 51 at the tip,
As shown in the enlarged view of part B in FIG.
The electric wires 51a, 51b having the same amount of current are contacted in parallel so as to be built in. This makes it possible to minimize the influence of the magnetic field generated by the heating wire 51.

The method of laying the heating wires 51 is desirably determined by laying the wires in a zigzag pattern as shown in FIG. . In addition, as a method of laying the heating wires 51, a method of laying the heating wires 51 in a spiral shape may be used.

When there is a concern about the temperature distribution on the heat conducting plate 40, as shown in FIG. 4, a plurality of temperature measuring devices 50a, 50b and 50c are embedded in the heat conducting plate 40 and the temperature distribution is observed. It is also possible to change the temperature control point.
This is because the size of the heat conducting plate 40 is larger than that of the sample 7,
This is particularly effective when the facing position between the sample 7 and the heat conductive plate 40 is shifted. In this case, the temperature measuring device used for controlling the temperature of the heat conducting plate 40 is set as a temperature measuring device 50b as a representative point, and the temperature difference between the observed temperature measuring devices 50a and 50c is set as an offset. It should be temperature.

In order to further improve the temperature uniformity on the heat conducting plate 40, as shown in FIG. 5, the surface of the heat conducting plate 40 facing the sample is made of a material having a high thermal conductivity, such as gold, graphite, silver or the like. It is effective to join the heat members 61 without gaps. Further, if a temperature measuring device is arranged so as to be in contact with the heat equalizing member 61, heat uniformity and temperature controllability are further improved.

In such a configuration, even if the thermal conductivity of the structural member 60 of the thermal conductive plate 40 is slightly reduced, the effect does not decrease so much. Therefore, a problem arises when a low-resistance material such as copper is used. In order to reduce the magnetic field fluctuation due to the eddy current, it is also possible to use a high resistance or insulating material such as high thermal conductivity ceramics (SiC, AlN) as the heat conductive plate structure member 60.

Further, as shown in FIG. 6, a planar heating element 62 using a high resistance material such as a tungsten material as the heating element can be joined to the surface. In this case, a method in which a planar heating element 62 is formed on the surface facing the sample and a heat equalizing member 61 having a high thermal conductivity is formed thereunder, or conversely, a structure in which the heat equalizing member 61 is formed on the surface is also possible. is there. Further, if the heat conductivity of the planar heating element 62 is sufficiently high, it can be formed directly on the surface of the heat conductive plate structural member 60.

Next, a method for avoiding the influence of noise due to the heating wires built into the heat conducting plate and the signal lines of the temperature measuring device will be described with reference to FIG.

FIG. 7 is a block diagram showing a control system of the heat conducting plate.

The heat conducting plate 40 has a heating wire 51 and a temperature measuring device 50 built therein. Since the length of the signal line connected to the heating wire 51 and the temperature measuring device 50 and the like becomes very long, it is inevitable that noise from the signal line serving as another noise source is picked up. In particular, since the signal lines of the heating wire 51 and the temperature measuring device 50 using the 4-wire platinum resistance temperature detector have high impedance, noise is easily picked up, and this noise affects charged particles, thereby deteriorating the drawing accuracy. May be. In such a case, during the irradiation of the charged particles, not only the power supply to the heating wire 51 is cut off, but also the heating wire 51 and Temperature measuring device 5
It is effective to ground one end of the signal line connected to 0.

Specifically, as shown in FIG. 7, the heating wires 51a, 51b and the temperature measuring wires 1 (56a, 56) of the temperature measuring device 50 are provided inside the stage temperature controller 41.
b) and a circuit for switching the temperature measurement unit wires 2 (57a, 57b) is provided, and the heating wires 51a, 51b can be switched, if necessary, to ground by the heating wire switch control signal 58. Although the configuration shown in FIG. 7 is configured so that both of the heating wires 51a and 51b can be grounded, a configuration in which one of the heating wires 51a and 51b is opened without being grounded may be considered.

The electric wire 1 of the temperature measuring section of the temperature measuring device 50
(56a, 56b) and the electric wire 2 (57a, 5
7b) is configured so that one is grounded and the other is opened by the temperature measurement unit wire switch control signal 59.
As a result, a circuit resistant to noise that cannot be looped can be provided.

As shown in FIG. 7, the switching operation of this switch is performed by the stage control device 32 connected to the stage temperature control device 41 or the drawing control device 31 connected to the stage control device 32. Device 5
4 is performed in response to a command.

In this embodiment, the heating electric wire switch control signal 58 and the temperature measuring electric wire switch control signal 59 are operated by the heat conduction plate temperature control device 54, but the stage control device 32 ahead of it. Alternatively, a similar effect can be obtained by a configuration that is directly operated from the drawing control device 31 or the like.

Next, a charged particle drawing apparatus according to a second embodiment of the present invention will be described. (Second Embodiment) FIG. 9 is a configuration diagram of a charged particle drawing apparatus according to a second embodiment of the present invention. is there.

The charged particle writing apparatus shown in FIG. 9 is the first stage 9 of the sample stage of the charged particle writing apparatus shown in FIG.
The heat conduction plate 42 is provided on the top. Heat conduction plate 42
Is similar to the heat conductive plate 40 described in the first embodiment. The heat conductive plate 42 is provided at a position facing the back surface of the sample table 3.

The function of the heat conducting plate 42 is the same as that of the heat conducting plate 40, but since the heat conducting plate 42 is installed at a place away from the sample 7, as in the case of the heat conducting plate 40, There is no need to consider measures against noise. Therefore, it is possible to increase the capacity of the heating wire.

The temperature of the heat conductive plate 42 is controlled by the stage temperature control device 41 in the same manner as the heat conductive plate 40. Therefore, the stage temperature control device 41 has a function of controlling the temperature of the heat conductive plate 42 in addition to the function of controlling the heat conductive plate 40 installed on the sample stage 3. The set temperatures of the heat conductive plate 40 and the heat conductive plate 42 can be set independently of each other.

Hereinafter, the function of the heat conductive plate 42 provided on the first stage 3 will be described.

The heat conductive plate 40 provided on the sample stage 3 uses a high-resistance heating wire so as to minimize the current when energized in order to reduce the influence of a magnetic field from a heating wire (not shown). Is done. Therefore, the amount of heat that can be generated by the heat conducting plate 40 is small, and when the temperature of the sample stage 3 is low and the amount of heat transferred from the heat conducting plate 40 to the sample stage 3 is larger than the heat capacity of the heat conducting plate 40, the heat conducting plate 40 cannot maintain a constant temperature.

On the other hand, in order to solve this problem,
When the temperature of the cooling plate 22 connected to 3 is brought close to the temperature of the heat conducting plate 40, the temperature of the first stage 9 is increased when the first stage 9 or the second stage 11 operates at a high frequency. The temperature of the heat conduction plate 40 may be exceeded. In such a state, the sample stage 3 is also heated from the lower first stage 9, and the temperature of the sample stage 3 exceeds the temperature of the heat conductive plate 40, and the temperature of the heat conductive plate 40 is controlled. May be impossible. However, the cooling plate 22
If the temperature of the first stage 9 is set so as not to exceed the temperature of the heat conducting plate 40 even if the first stage 9 and the second stage 11 move frequently by lowering the temperature of As described above, the amount of heat generated by the heat conduction plate 40 is insufficient, so that the heat conduction plate 40 cannot be maintained at a constant temperature.

To solve this problem, it is possible to change the temperature of the cooling plate 22 depending on the temperature of the first stage 9 or the second stage 11, but
The first stage 9 has good response because the thermal conductivity coefficient of the stage material is not large and the volume is large and the heat capacity is large.
It is difficult to control the temperature.

Therefore, the first stage 9 is provided with the heat conducting plate 4
If the temperature control is performed by connecting the heat conductive plate 42 having a heat generation capacity larger than 0, the temperature of the cooling plate 22 can be controlled by the first stage even when the first stage 9 and the second stage 11 move frequently. 9 is set to be lower than the temperature of the heat conducting plate 40. Thereby, it is possible to prevent the temperature of the first stage 9 from rising excessively. Here, further, the first stage 9 is controlled so that the temperature of the first stage 9 does not excessively decrease when the stage does not move.
If the set temperature of the heat conductive plate 42 provided above is set higher than the temperature of the cooling plate 22 and the temperature of the sample stage 3 is set higher than the lower limit of the temperature control of the heat conductive plate 40, the stage moves. When the number is small, heat can be supplied to the first stage 9 and further to the sample table 3 by the heat conductive plate 42 to keep the temperature control of the heat conductive plate 40 always possible. Further, when the stage is frequently moved, the heat generated by the heat conductive plate 42 is reduced to increase the cooling efficiency of the cooling plate 22 so that the heat conductive plate 40 provided on the sample stage 3 can always be controlled at a constant temperature. be able to.

This effect is similar to the case of the charged particle lithography system according to the first embodiment, even if the stage has a single moving stage and can move two-dimensionally on a plane. It goes without saying that a similar effect can be obtained by using the first stage 9 shown in FIG. This is the same in the following description.

Next, a method of improving the cooling efficiency of the stage by the cooling plate 22 and thus the sample stage 3 will be described with reference to FIGS.

FIG. 10 is a side view of the sample stage of the charged particle drawing apparatus shown in FIG. 9 in which measures for improving the cooling efficiency of the cooling plate 22 are taken.

In this sample stage, a heat transfer promoting member 70 in the form of a sheet of copper or graphite having a high thermal conductivity is connected to the second stage 11 directly from the base 13 or the cooling plate 22 to which the cooling plate 22 is connected. Further, the heat transfer promoting member 71 is connected to the upper surface of the first stage 9, and the heat transfer promoting member 72 is connected to the lower surface of the sample stage 3 thereon. With such a configuration, a heat transfer path for cooling the sample stage 3 and the first stage 9 is provided by the sample stage support device 8, the first stage 9,
Guide device 10 for first stage 9, second stage 1
In addition to the paths of the guide device 12 and the base 13 of the first and second stages, the paths of the heat transfer promoting members 70, 71, and 72 are also added. Stage 9 can be efficiently cooled.

The heat transfer accelerating member 72 connecting the sample stage 3 and the first stage 9 is unnecessary when the thermal conductivity of the sample stage supporting device 8 is sufficiently high. Since the contact area with each stage at 10 and 12 is small, if a copper tape or a graphite sheet having a heat conductivity of 100 times or more of the material of the stage or the material of the guide device is used as the heat transfer promoting members 70 and 71, It is possible to sufficiently improve the cooling efficiency of the cooling plate 22.

However, actually, the first stage 9 and the second stage 9
Since the stage 11 moves in a right angle direction, the connection method as shown in FIG. 10 is difficult. Specifically, as shown in FIG. 11, the tape-shaped heat transfer promoting members 70 and 71 are respectively connected to the second. The stage 11 and the first stage 9 are connected so as not to hinder the movement thereof, and these heat transfer promoting members 70,
71 is connected by a member of the same material.

In this type of sample stage, the sample stage 3
Alternatively, the heat conductive plates 40, 4 installed on the first stage 9
2 and other sensors, etc., are pulled out to the base 13 or a sample chamber (not shown) by a similar mechanism. Therefore, the copper tape or the graphite sheet described above is used as a member for supporting these wires. It is also effective to use the heat transfer promoting members 70 and 71 used. As shown in FIG. 10, a heat equalizing member 73 having a high thermal conductivity, such as copper or graphite, is joined without any gap to almost the entire surface connecting the heat transfer promoting member 72 to the sample stage 3. If the heat equalizing member 74 is also fixed to 9 and the heat transfer promoting member 72 is connected to the heat equalizing members 72 and 73, the cooling efficiency of the cooling plate 22 can be further improved. However, if the heat conductive plates 40 and 42 are brought into contact with the heat equalizing members 72 and 73, the heat generated by the heat conductive plates 40 and 42 is transferred more than necessary. In addition, it is preferable that the heat conducting plate 42 does not contact the heat equalizing members 72 and 73.

Next, a method of drawing by actually operating the above-described charged particle drawing apparatus will be described.

As described above, in the charged particle writing apparatus of the present invention, the temperature of the sample table 3 (the temperature of the heat conducting plate 40 connected to the sample table 3) and the temperature of the The temperature of the stage cooling device such as the cooled cooling plate 22, the temperature of the stage (the temperature of the heat conducting plate 42 connected to the first stage 9), the temperature of the sample chamber 2, and the like.

First, in the charged particle drawing apparatus as shown in FIG. 1, the temperature of the sample stage 3 is almost set by the temperature of the connected heat conducting plate 40. In general, the set temperature is set so as to match the temperature when a sample such as a photomask is used in an apparatus such as a stepper after drawing. Therefore, the temperature of the heat conduction plate 40 is set to a predetermined temperature by the stage temperature control device 41, and the temperature control of the heat conduction plate 40 is started.

The temperature of the sample chamber 2 outside the sample stage can be set to any temperature.
If there is a temperature difference between the sample table 3 and the temperature of the sample table 3, heat is transferred to the sample table 3 due to radiant heat or the like, which affects the temperature control of the sample table 3 and the heat conductive plate 40. Therefore, in order to match the temperature of the sample chamber 2 with the temperature of the sample table 3, the set temperature of the sample chamber constant temperature water control device 21 is made equal to the set temperature of the stage temperature control device 41. Thereby, the temperature of the sample stage 3 can be easily stabilized.

In addition, when a device such as a stepper that uses a sample after drawing is in the same temperature environment, not only a device such as a stepper but also a charged particle drawing device is used under the temperature of the environment. Therefore, if the temperature of the sample chamber 2 is adjusted to the surrounding environment temperature, there is a case where a temperature gradient cannot be formed in the sample chamber of the charged particle writing apparatus and high-precision writing can be performed.
In this case, first, the temperature of the sample chamber constant temperature water control device 21 is set so as to match the temperature of the surrounding environment, and further, the stage temperature control device is set so that the temperature becomes the temperature of the heat conducting plate 40 connected to the sample stage. The temperature of 41 is set.

Next, the heat conductive plate 40 connected to the sample stage 3
In order to facilitate the temperature control, the temperature of the stage below the sample stage 3 is circulated through the cooling plate 22 connected to the base 13, and the temperature of the constant temperature water is previously set by the stage constant temperature water controller 24. The temperature is set lower than the temperature of the plate 40.
The set temperature is determined so that the temperature of the stage does not exceed the temperature of the sample stage due to heat generated by movement of the sample stage.

As described above, by setting the temperature of each part and drawing the sample after the temperature of each part is stabilized, high-precision drawing becomes possible.

Next, the case of a charged particle drawing apparatus as shown in FIG. 2 will be described. Even in this case, it is not possible to set the temperatures of the stage temperature control device 41 and the sample room constant temperature water control device 21 so that the temperature of the heat conduction plate 40 connected to the sample stage 3 and the temperature of the sample room 2 are substantially the same. Is the same.

Next, a heat conduction plate 42 provided on the first stage 9 is provided so that the sample stage is not excessively cooled.
The heat conduction plate 4 provided on the sample stage 3 having a predetermined temperature
The temperature of the stage temperature control device 41 is set so that the temperature is somewhat lower than 0. However, this temperature is equal to or higher than the lower limit temperature at which the temperature of the heat conductive plate 40 connected to the sample stage 3 can be controlled as described above. After that, even if the stage is frequently moved, the temperature of the constant temperature water of the cooling plate 22 connected to the base 13 is adjusted so that the temperature of the stage does not exceed the predetermined temperature of the heat conducting plate 42. It is set by the control device 24.

By performing drawing after the temperature of each part is stabilized through these steps, it becomes more resistant to temperature disturbance such as stage movement and the like, and highly accurate drawing becomes possible.

Next, a method for obtaining high drawing accuracy by using the charged particle drawing apparatus as shown in FIG. 1 to minimize the influence of magnetic field fluctuation or noise due to the heat conducting plate 40 connected to the sample table 3 will be described. explain.

FIG. 8 shows ON / OFF of irradiation of charged particles such as an electron beam, ON / OFF of a stage operation, and the like when drawing on a sample using the charged particle drawing as shown in FIG.
ON / OF of the temperature control of the heat conduction plate that determines the temperature of the sample stage
FIG. 8 is a diagram showing an example of the transition timing of F and the transition of the temperature of the heat conductive plate connected to the sample stage at that time.

Before writing on the sample, a stage operation may be performed to carry in the sample or the like. However, since the electron beam is not irradiated, the temperature control of the heat conductive plate is continued, and Stabilize the temperature. Thereafter, the stage operation is performed up to the writing start point in order to write the sample, but the temperature control of the heat conductive plate can be continued during this time. Then, the stage starts to operate for drawing, and immediately before the electron beam is irradiated, the temperature control of the heat conductive plate is stopped. Thereby, a drawing error caused by a magnetic field fluctuation due to the heat conductive plate during drawing can be eliminated.

When a temperature control system for the heat conducting plate as shown in FIG. 7 is provided, the switch is operated to ground one end of the heating wire or the wire of the temperature measuring device. It is possible to minimize the influence of noise derived from the wiring. When the irradiation of the sample with the electron beam is completed, the stage moves to the next drawing start point. However, since the irradiation of the electron beam has already been completed, the temperature control of the heat conductive plate is restarted immediately after the irradiation is completed. During this time, the temperature control of the heat conduction plate is stopped, so that the temperature of the heat conduction plate slightly decreases. However, by shortening the time of the temperature control as much as possible based on a signal from a deflection control device or the like included in the drawing control device 31, , It is possible to minimize the amount of temperature drop. Also, since the heat conduction plate is heated by the heating wire,
In particular, it responds to the direction of increasing the temperature with good response, and it is possible to return the temperature of the heat conducting plate to the set temperature.

In addition, there is a case where an electron beam is irradiated on a mark or the like on the sample table 3 for adjusting the electron beam without irradiating the sample with the electron beam. It is more effective if the temperature control is stopped immediately before the irradiation of the electron beam by a control device or the like, and the temperature control is restarted after the irradiation is completed.

Next, a description will be given of a flow of steps when drawing a sample with the charged particle drawing apparatus as shown in FIG.

FIG. 12 is a flowchart showing the steps of drawing a sample, and FIG. 13 is a graph showing an example of the transition of the temperature of the heat conducting plate during that.

First, prior to writing, the temperature of the heat conductive plate connected to the sample stage is set by the method described above (S
1) The temperature control of the heat conductive plate of the sample stage is started to stabilize the temperature of the heat conductive plate (S2). Next, the sample is carried into the sample stage (S3), and the temperature of the heat conducting plate at that time is measured (S3).
4). For example, when the temperature of the sample is higher than the temperature of the heat conductive plate, as shown in FIG. 13, the temperature of the heat conductive plate temporarily rises due to the effect of radiation. If this temperature is within the preset drawing temperature range (S5), there is no problem and drawing is started (S7). If the temperature of the heat conductive plate is outside the drawing temperature range, the sample is started. Is naturally outside the drawable range, so that drawing is not started and the process stands by (S6).
Since the temperature control of the heat conductive plate is performed, the calorific value of the heat conductive plate decreases, and the temperature of the heat conductive plate returns to the original set temperature. At this time, since the sample also depends on the temperature of the heat conductive plate, the temperature of the heat conductive plate is measured again (S4), and if the temperature of the heat conductive plate is within the temperature range where drawing is possible (S5), drawing is performed. Start.

When a sample is drawn, the temperature of the sample rises because the sample absorbs the energy of charged particles such as electron beams. Accordingly, the temperature of the heat conducting plate may also increase. For this reason, when the pattern to be drawn on the sample is divided into certain drawing areas such as stripes, the temperature of the heat conductive plate is measured at the end of drawing in the drawing area (S4), and as described above. It is checked whether the temperature of the heat conducting plate is within the drawable range (S5). If the temperature is within the drawable temperature range, drawing of the next drawing area is restarted (S7).
If the above steps are repeated and the writing of all the writing areas is completed (S8), the sample is unloaded (S9) and the processing ends.

By taking such steps, the specimen can be drawn within the temperature range necessary to always obtain the required drawing accuracy, and very high drawing position accuracy can be realized.

[0097]

As described above, according to the present invention,
The temperature of the sample stage of the sample stage in the sample chamber can be controlled with high accuracy, and the temperature difference between the sample and the sample stage can be measured, and the difference can be drawn more quickly within the required range. A charged particle writing apparatus capable of realizing high writing position accuracy can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a charged particle drawing apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a sample stage used in the charged particle writing apparatus of the present invention.

FIG. 3 is a plan view, a B sectional view, and an A section enlarged view of a heat conducting plate used for a sample stage of the charged particle drawing apparatus of the present invention.

FIG. 4 is a plan view of different heat conductive plates used for a sample stage of the charged particle writing apparatus of the present invention.

FIG. 5 is a cross-sectional view of a different heat conductive plate used for a sample stage of the charged particle writing apparatus of the present invention.

FIG. 6 is a cross-sectional view of a different heat conducting plate used for the sample stage of the charged particle writing apparatus of the present invention.

FIG. 7 is a configuration diagram showing a control system of a heat conductive plate used for a sample stage of the charged particle writing apparatus of the present invention.

FIG. 8 is a timing chart showing a control example of a heat conductive plate used for a sample stage of the charged particle writing apparatus of the present invention.

FIG. 9 is a configuration diagram of a charged particle drawing apparatus according to a second embodiment of the present invention.

FIG. 10 is a side view of a sample stage of the charged particle writing apparatus according to the second embodiment of the present invention.

FIG. 11 is a perspective view of a sample stage of the charged particle writing apparatus according to the second embodiment of the present invention.

FIG. 12 is a flowchart showing a drawing method of the charged particle drawing apparatus of the present invention.

FIG. 13 is a graph showing an example of transition of the temperature change of the heat conductive plate of the sample stage when the drawing method of the charged particle drawing apparatus of the present invention is performed.

FIG. 14 is a configuration diagram showing a conventional charged particle drawing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electron optical column 2 ... Sample chamber 3 ... Sample table 6 ... Sample support means 7 ... Sample 8 ... Sample table support means 9 ... 1st stage 10. ..Guide device 11 ・ ・ ・ Second stage 12 ・ ・ ・ Guide device 13 ・ ・ ・ Base 20 ・ ・ ・ Sample chamber constant temperature water pipe 22 ・ ・ ・ Stage cooling plate 23 ・ ・ ・ Stage constant temperature water pipe 40, 42 ... Heat conduction plate 50 ... Temperature measurement part 51,51a, 51b ... Heat generation wire 56a, 56b ... Temperature measurement part wire 57a, 57b ... Temperature measurement part wire 58 ... Heat generation wire switch Control signal 59 ... Temperature measuring unit electric wire switch control signal 60 ... Heat conductive plate structural member 61,73,74 ... Heat equalizing member 62 ... Sheet heating member 70,71,72 ... Transmission Heat promoting member

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toru Tojo 1 Kosuka Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa F-term in the Toshiba R & D Center (reference) 2H097 CA16 GB00 LA10 5C001 AA01 BB01 CC06 5C034 BB06 5F056 CD05 EA12 EA14

Claims (5)

[Claims] A sample chamber for introducing a sample, a sample table provided in the sample chamber, the sample table being capable of holding the sample so that the charged particles are irradiated onto the sample surface; A heat generating means provided in a, a temperature measuring means for detecting a temperature of the sample, a stage mounted with the sample stage, and capable of moving the sample stage in at least one direction, and a base holding the stage, A cooling unit provided on the base; and a temperature control device for controlling the heating unit based on an output of the temperature measurement unit, wherein the heating by the heating unit is performed while the charged particles are irradiated on the sample. A charged particle drawing apparatus, which is stopped. 2. The charged particle drawing apparatus according to claim 1, wherein said heat generating means is an electric heating device, and heat generation is controlled by controlling an applied current by said temperature control device. 3. The charged particle drawing apparatus according to claim 1, wherein said heat generating means is provided on a heat conductive plate on said sample stage, and said temperature measuring means is provided on said heat conductive plate. . 4. The charged particle drawing apparatus according to claim 2, wherein said heating means and said temperature measuring means are grounded while said charged particles are irradiated on said sample. 5. The charged particle drawing apparatus according to claim 1, further comprising a heating means and a temperature measuring means on said stage.