JP2004304032A - Charged beam drawing method - Google Patents

Abstract

The present invention compensates for a temperature change of a substrate due to evacuation in a short period of time and stabilizes it with high accuracy, thereby realizing both throughput and drawing accuracy.
In a constant temperature vacuum chamber, a substrate having a thermal conductivity of 100 W / mK or more and an emissivity of 0.4 or more with respect to a substrate to be drawn has a temperature sensor mounted on its surface. The substrate 17 is conveyed into the constant temperature vacuum chamber 11 and mounted on the support mechanism 12 by monitoring the detection output of the temperature sensor 15 by installing the temperature control plate 13 face-to-face. The change is detected, and the substrate temperature is stabilized by leaving the substrate 17 in the constant temperature vacuum chamber 11 until the temperature change converges to a predetermined range.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a charged beam writing method using an electron beam, an ion beam, or the like, and more particularly, to a charged beam writing method for stabilizing the temperature of a substrate to be drawn in a constant temperature vacuum chamber before drawing.
[0002]
[Prior art]
2. Description of the Related Art In recent years, demands for pattern accuracy and throughput are becoming stricter in a charged beam lithography apparatus that forms a circuit pattern on a semiconductor substrate, a master mask substrate for exposure, a liquid crystal substrate panel substrate, or the like, which is a typical semiconductor manufacturing apparatus.
[0003]
Regarding pattern accuracy, it is necessary to eliminate and manage external precision deterioration factors such as temperature fluctuations, as well as to improve and stabilize the electrical, control, and mechanical system. Since the drawing position accuracy in recent years is required to be approximately 20 nm, it is necessary to achieve a budget for each error factor. When the temperature of the substrate changes before and after writing, the substrate size changes due to thermal expansion, and the positional accuracy of the drawn pattern deteriorates. A normal photomask has a thermal expansion coefficient of 0.5 × 10 ^-6 / ° C., and a temperature change of 1 ° C. causes a displacement of 66 nm in a 132 mm area, for example. Therefore, in order to achieve a writing position accuracy of 20 nm, for example, if the position accuracy budget given to the temperature factor is 4 nm, it is necessary to keep the temperature constant within a range of about 0.06 ° C.
[0004]
On the other hand, with respect to the throughput, the influence of the so-called overhead time, such as the substrate transfer time and the time required for setup before starting drawing, is increasing. In particular, in the transfer, when the vacuum preliminary chamber is evacuated, the temperature of the substrate is reduced due to adiabatic expansion. From the viewpoint of the drawing accuracy, the temperature lowered by resturing the substrate at a constant temperature is returned to a predetermined temperature. However, this stabilization time is generally longer than the transporting time itself. When the substrate temperature is settled to a predetermined temperature in a vacuum, heat exchange by radiation between the substrate and surrounding objects (for example, walls of a constant temperature vacuum chamber) becomes dominant. Therefore, for example, assuming that there is a difference of about 0.5 ° C. between the temperature of the substrate and the surroundings, the time required for the stabilization is as long as 5 hours or more.
[0005]
Further, the value of the temperature decrease of the substrate due to the evacuation is different depending on various conditions, but is about 0.2 to 1 ° C. in the experimental results. This value is larger than the required temperature uniformity of 0.06 ° C. in terms of the accuracy budget, and is one of the factors requiring the most measures as a temperature fluctuation factor. In the future, a position accuracy of about 10 nm will be required. In this case, assuming that the accuracy budget due to the temperature is half of the above, it is expected that a temperature uniformity of 0.03 ° C. or less will be required. Further, in order to accurately measure such a minute temperature and control the temperature, it is generally desired to perform the measurement with an accuracy of about 1/10 of the target temperature. Requires measurement at 0.003 ° C. (on the order of 0.001 ° C.).
[0006]
Furthermore, in the process of stabilizing the substrate temperature, it is necessary to monitor the state of the substrate temperature during the stabilization, determine that the stabilization has been completed, and move on to the next step. It becomes. In the method of measuring the time required for stabilization using a substrate with a temperature sensor in advance, sufficient stabilization management is not possible when stabilizing substrates in different temperature states. Not only could it not be stabilized, but there were variations in the static settling temperature. As a result, there has been a problem that the temperature is fluctuated at the time of writing and the accuracy is deteriorated. Also, when using a method or means for positively heating and using a temperature control means to keep the substrate temperature constant, it is necessary to monitor the state of the substrate temperature with high accuracy and determine that the stabilization has been completed. There is no substitute for that, but until now it was not managed with sufficient accuracy.
[0007]
With respect to these problems, various proposals have been made to compensate for a temperature decrease of the substrate caused by evacuation in particular (for example, see Patent Documents 1 to 4). However, in these proposals, a temperature preheating means or a temperature control means is provided in a pre-vacuum chamber for evacuating to compensate for a temperature drop of the substrate. To stabilize the temperature of the substrate, which requires a relatively long time, in a pre-chamber, which is located in the middle of the transfer path and has the function of frequently loading and unloading substrates from the atmosphere in a vacuum atmosphere, such as a vacuum pre-chamber. May hinder the conveyance and may not be able to sufficiently improve the throughput.
[0008]
A method has also been proposed in which the substrate is heated in advance so that the temperature of the substrate becomes higher than the set temperature in the exposure chamber when the intermediate chamber is evacuated (see Patent Document 5, for example). . In this case, it is premised that the value of the temperature drop due to the evacuation of the substrate is reproduced with sufficient accuracy, and if the reproducibility is insufficient, application becomes difficult. Further, it is not possible to control whether or not the actual substrate temperature is sufficiently stabilized, and there is a problem in application to a substrate having different materials and different temperature characteristics such as thermal conductivity.
[0009]
A method has also been proposed in which a sample holder is effectively heated as a heating element to compensate for a slight temperature difference quickly and accurately (for example, see Patent Document 6). This method makes it easier to perform accurate and accurate temperature control compared to the conventional method, and considers the convergence curve of the temperature change of the sample holder, so that it is also possible to determine the time when the temperature of the sample holder has converged. Will be possible. However, only the temperature of the sample holder is monitored, and there is a possibility that the management of whether the temperature of the mounted sample itself is stabilized may be insufficient.
[0010]
[Patent Document 1]
JP-A-10-233423
[0011]
[Patent Document 2]
JP-A-10-284389
[0012]
[Patent Document 3]
JP-A-10-321960
[0013]
[Patent Document 4]
JP-A-2001-222099
[0014]
[Patent Document 5]
JP-A-10-284373
[0015]
[Patent Document 6]
JP 08-97130 A
[0016]
[Problems to be solved by the invention]
As described above, conventionally, various methods have been proposed to make the temperature of the substrate to be drawn constant, and by these methods, it is basically impossible to quickly set the temperature of the object to be processed to a desired temperature. Although possible, there is a problem in reducing the overhead time during transport as described above. In addition, it has been practically difficult to perform time management on temperature measurement with high accuracy on the order of 0.001 ° C. and temperature stabilization of the substrate. For this reason, it has been difficult to shorten the overhead time at the time of transport, improve the throughput, and achieve both high precision drawing accuracy.
[0017]
The present invention has been made in consideration of the above circumstances, and has as its object to reduce the stabilization time for stabilizing the temperature of a substrate that has fluctuated due to evacuation during transportation. Another object of the present invention is to provide a charged beam writing method which realizes both throughput and writing accuracy.
[0018]
[Means for Solving the Problems]
(Constitution)
In order to solve the above problems, the present invention employs the following configuration.
[0019]
That is, according to the present invention, a substrate to be drawn to be subjected to charged beam writing is preliminarily kept at a constant temperature in a constant temperature vacuum chamber, the constant temperature substrate is transported into a drawing chamber, and a desired pattern is drawn on the substrate in the drawing chamber. In the charged beam writing method, a support mechanism for supporting the substrate, disposed above or below or both of the support mechanism, facing the substrate in the constant temperature vacuum chamber, and having an area equal to or larger than the substrate. And a temperature control plate comprising a structure coated with a conductive carbon-containing material having a heat transfer coefficient of 100 W / mK or more and a surface having an emissivity of 0.4 or more; A temperature adjusting mechanism for controlling the temperature of the plate, and a temperature sensor disposed on or inside the temperature control plate for detecting the temperature of the plate are provided, By constantly or intermittently monitoring the output, the temperature change generated in the temperature control plate due to the substrate being transferred into the constant temperature vacuum chamber or being mounted on the support mechanism is detected. The substrate temperature is stabilized by leaving the substrate in the constant temperature vacuum chamber until the temperature change converges to a predetermined range.
[0020]
According to the present invention, a substrate to be drawn to be subjected to charged beam writing is preliminarily kept at a constant temperature in a constant temperature vacuum chamber, the substrate at a constant temperature is transferred into a drawing chamber, and a desired pattern is drawn on the substrate in the drawing chamber. In the charged beam writing method, a support mechanism for supporting the substrate, disposed above or below or both of the support mechanism, facing the substrate in the constant temperature vacuum chamber, and having an area equal to or larger than the substrate. And a temperature control plate comprising a structure coated with a conductive carbon-containing material having a heat transfer coefficient of 100 W / mK or more and a surface having an emissivity of 0.4 or more; A temperature adjusting mechanism for controlling the temperature of the plate, and a temperature sensor disposed at a substrate contact portion of the support mechanism for detecting the temperature of the substrate are provided, and a detection output of the temperature sensor is provided. Is constantly or intermittently monitored to detect a temperature change occurring when the substrate is transferred into the constant temperature vacuum chamber or mounted on the support mechanism, and the temperature change converges to a predetermined range. The substrate temperature is stabilized by leaving the substrate in the constant temperature vacuum chamber until the substrate temperature is reduced.
[0021]
Here, preferred embodiments of the present invention include the following.
[0022]
(1) A temperature sensor made of a platinum resistor having a temperature measurement resolution of 0.001 ° C. or less is used as the temperature sensor.
[0023]
(2) By actively controlling the temperature of the temperature control plate based on the detection output of the temperature sensor, stabilizing the temperature of the substrate faster than in the case where the temperature of the temperature control plate is constantly controlled.
[0024]
(3) As the temperature sensor, both a temperature sensor arranged on the surface or inside the temperature control plate to detect the temperature of the plate and a temperature sensor arranged at the substrate contacting portion of the support mechanism to detect the temperature of the substrate And stabilize the substrate temperature based on the measurement results of both.
[0025]
Also, the present invention includes a transfer means for transferring a substrate coated with a photosensitive resist, a load lock chamber, a constant-temperature vacuum chamber equipped with a support mechanism for supporting the substrate, and a moving stage on which the substrate is mounted. A charged beam writing apparatus having at least a vacuum writing chamber for performing writing, in the constant temperature vacuum chamber, disposed above or below the support mechanism or both, and equivalent to or more than the substrate A temperature control plate comprising a structure having an area and having a heat transfer coefficient of 100 W / mK or more and having a surface coated with a conductive carbon-containing material having an emissivity of 0.4 or more; A temperature adjusting means connected to the plate; and a temperature measuring sensor comprising one or more platinum resistors provided on or on the surface of the plate. The temperature of the temperature sensor is monitored by a measuring unit that constantly or intermittently measures the temperature, and a temperature change generated when the substrate is transferred into the constant temperature vacuum chamber or mounted on the support mechanism is detected. A function of stabilizing the substrate temperature by leaving the substrate in a constant-temperature vacuum chamber while managing a time response until the temperature change converges to a predetermined temperature range equivalent to the temperature of the charged beam writing chamber. It is characterized by having.
[0026]
Also, the present invention includes a transfer means for transferring a substrate coated with a photosensitive resist, a load lock chamber, a constant-temperature vacuum chamber equipped with a support mechanism for supporting the substrate, and a moving stage on which the substrate is mounted. A charged beam writing apparatus having at least a vacuum writing chamber for performing writing, in the constant temperature vacuum chamber, disposed above or below the support mechanism or both, and equivalent to or more than the substrate A temperature control plate comprising a structure having an area and having a heat transfer coefficient of 100 W / mK or more and having a surface coated with a conductive carbon-containing material having an emissivity of 0.4 or more; And a temperature sensor built in the substrate contacting portion of the support mechanism inside the chamber. The temperature of the substrate is monitored by measuring means for measuring the temperature of the substrate constantly or intermittently, and a temperature change generated by mounting the substrate on the support mechanism is detected. A function of stabilizing the substrate temperature by leaving the substrate in a constant-temperature vacuum chamber while managing a time response until the temperature converges to a predetermined temperature range is provided.
[0027]
(Action)
According to the present invention, it is possible to quickly set the temperature of the substrate to a desired temperature by using a temperature control plate having a high thermal conductivity and a high emissivity for the temperature control plate facing the substrate, and further, By attaching the temperature sensor to a plate having a high emissivity, the response of a temperature change due to radiation from the facing substrate can be monitored with high sensitivity and high accuracy. By realizing this high-precision monitoring, the time required for stabilization can be managed with high accuracy, and unnecessary time can be eliminated to improve the throughput. Furthermore, since the temperature of the substrate itself is not directly measured, there is no problem of dust generation, and the substrate stabilization temperature can be kept constant even when substrates of various temperatures are conveyed.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. Here, a drawing apparatus for an original mask substrate for exposure will be described as an example.
[0029]
(1st Embodiment)
FIG. 1 is a schematic configuration diagram showing a constant temperature vacuum chamber used for an electron beam writing apparatus according to the first embodiment of the present invention.
[0030]
The constant temperature vacuum chamber 11 is maintained at a constant temperature, and has a support mechanism 12 for supporting a substrate to be drawn therein. At the upper end of the supporting mechanism 12, a glass mask substrate 17 as a substrate to be drawn is supported. In this example, the glass mask substrate 17 is mounted by its own weight. A temperature control plate 13 is disposed below the support mechanism 12, that is, at a portion located on the back side of the substrate 17, and a temperature control unit 14 is connected to the temperature control plate 13.
[0031]
As shown in FIG. 2, a pipe 23 is formed inside the temperature control plate 13, and temperature control by water flow is performed between the temperature control plate 13 and the temperature control unit 14. The temperature of the water flowing for temperature control is controlled to be constant at an accuracy of 1/100 ° C. at the discharge temperature. As shown in the figure, the temperature control plate 13 is formed by depositing conductive diamond-like carbon with a thickness of 5 μm as a coating film 22 on the surface of a plate base material 21 made of a copper plate. By imparting conductivity as described above, the accumulation of electric charge is prevented, and adhesion of particles due to static electricity is prevented.
[0032]
A platinum resistor (Pt100) as a temperature sensor 15 is in close contact with the upper surface side of the temperature control plate 13, and the temperature sensor 15 is connected to a temperature measurement unit 16. With the configuration shown in FIGS. 1 and 2, the temperature control plate 13 has a function as a temperature control plate having an emissivity of 0.8 or more and a thermal conductivity of about 400 W / mK. In the present embodiment, the temperature of the constant temperature vacuum chamber 11, the support mechanism 12, and the temperature control plate 13 are all set to 23 ° C.
[0033]
In such a configuration, when a substrate 17 having a temperature different from 23 ° C. is transferred to the constant temperature vacuum chamber 11, the temperature sensor 15 attached to the temperature control plate 13 responds to a difference in temperature between the substrate 17 and the opposing substrate 17. As a result, it is subjected to a temperature change due to radiant heat. Since the substrate 17 is a normal glass mask, the emissivity is about 0.8, and the emissivity of one of the temperature control plates 13 is sufficiently large to be equal to or more than that. The sensitivity of the temperature response of the sensor 15 becomes extremely large. For this reason, even with a slight temperature difference, a sufficient temperature change occurs in the temperature sensor 15. By performing the measurement of the temperature change, static determination necessary for stabilizing the temperature of the substrate 17 is performed.
[0034]
Here, the temperature control plate 13 needs to have a uniform temperature distribution on the surface facing the substrate 17, and its thermal conductivity must be sufficiently high. According to experiments by the present inventors, it has been confirmed that a sufficiently uniform temperature distribution can be obtained by setting the thermal conductivity of the temperature control plate 13 to 100 W / mK or more. Further, in order to quickly exchange heat with the substrate 17, the emissivity of the temperature control plate 13 on the substrate facing surface must be sufficiently large. According to experiments by the present inventors, it was confirmed that rapid heat exchange with the substrate 17 can be realized if the emissivity on the surface of the temperature control plate 13 is 0.4 or more.
[0035]
In the same configuration, based on the output result of the temperature response of the temperature sensor 15, the temperature of the temperature control plate 13 is actively controlled so that the output result becomes constant within a predetermined temperature range. It is possible to shorten the time for stabilizing. As an active temperature control method, for example, when the temperature of the substrate 17 is considered to be lower than the set temperature, the temperature control plate 13 may be temporarily set to be higher than the set temperature.
[0036]
In this case, the temperature response of the temperature adjustment plate 13 connected to the temperature adjustment unit 14 needs to be performed as instructed by the temperature adjustment unit 14. Therefore, by forming the temperature control plate 13 using a material having a heat transfer coefficient that is sufficiently larger than the heat transfer coefficient of stainless steel frequently used as a material of the outer wall of the chamber, for example, 100 W / mK or more, which is one digit larger. In addition, active temperature control can be performed with high accuracy without being hindered by the cycle of temperature fluctuation of the outer wall of the chamber.
[0037]
As described above, according to the present embodiment, the temperature of the substrate 17 is quickly set to a desired temperature by using the temperature control plate 13 having a large thermal conductivity and a high emissivity facing the substrate 17. be able to. Further, by attaching the temperature sensor 15 to the plate 13 having a high emissivity, the response of the temperature change due to the radiation from the facing substrate 17 can be monitored with high sensitivity and high accuracy.
[0038]
Therefore, the time required for stabilization can be managed with high accuracy, and waste time can be eliminated to improve throughput. Further, since the temperature of the substrate itself is not directly measured, there is no problem of dust generation, and the substrate stabilization temperature can be kept constant even when substrates of various temperatures are conveyed. That is, it is possible to shorten the stabilization time for stabilizing the temperature of the substrate that has fluctuated due to evacuation or the like during the transfer, and achieve both throughput and drawing accuracy.
[0039]
(Second embodiment)
Next, another configuration example of the constant temperature vacuum chamber will be described as a second embodiment of the present invention with reference to FIG.
[0040]
The configuration of the constant temperature vacuum chamber of FIG. 3 differs from the configuration of FIG. 1 in that the temperature sensor 35 is built in a support portion of the support mechanism 12 near the substrate 17 in contact therewith. Other parts that are the same as those in FIG. 1 are indicated by the same numbers.
[0041]
In the case of the present embodiment, when the substrate 17 having a different temperature is mounted on the support mechanism 12, heat is exchanged by heat conduction due to contact thermal resistance via the contact portion between the two, so that the substrate 17 is in the vicinity. The temperature change is measured by the built-in temperature sensor 35. By performing the measurement of the temperature change, static determination necessary for stabilizing the temperature of the substrate 17 is performed. Also in the present embodiment, based on the output result of the temperature response of the temperature sensor 35, the temperature of the temperature control plate 13 is actively controlled so that the output result becomes constant within a predetermined temperature range, thereby controlling the temperature of the substrate. It is possible to shorten the time for stabilizing.
[0042]
(Third embodiment)
Next, still another configuration example of the constant temperature vacuum chamber will be described as a third embodiment of the present invention with reference to FIG.
[0043]
The configuration inside the constant temperature vacuum chamber 11 is a combination of the configurations shown in FIGS. 1 and 2, and has a temperature sensor 45 on the temperature control plate 13 and a temperature sensor 46 built in the tip of the support mechanism 12. By measuring the change in temperature received by these sensors 45 and 46, static determination necessary for stabilizing the temperature of the substrate 17 is performed. Also in this configuration, based on the output results of the temperature responses of the temperature sensors 45 and 46, the temperature of the temperature control plate 13 is actively controlled so that the output results become constant within a predetermined temperature range. It is possible to shorten the time for stabilizing the temperature.
[0044]
Next, in the first and third embodiments, the results of estimating the required emissivity by examining the emissivity of the temperature control plate necessary for temperature measurement accuracy as described below will be described.
[0045]
If the amount of change in the temperature sensors 15 and 45 on the temperature control plate 13 is small when the substrate 17 is transported and mounted on a support pin or the like of the support mechanism 12, the time response of this temperature change can be monitored. This may make it difficult to stabilize the substrate sufficiently and manage the stabilization time without waste. In order to solve this problem, as long as the temperature difference between the substrate 17 and the temperature control plate 13 is not very small, for example, when the temperature change caused by evacuation is smaller, the temperature sensors 15 and Sufficient measurement accuracy can be ensured by setting a condition such that a temperature change amount of 0.01 ° C., which is 10 times larger than the temperature measurement resolution (0.001 ° C. in the present embodiment), occurs in 45. Therefore, when there is a temperature difference of 0.3 ° C., it is useful to define the emissivity of the temperature control plate necessary to secure sufficient measurement accuracy.
[0046]
Therefore, in consideration of radiation between the glass substrate 17 and the two surfaces of the temperature control plate 13, the relationship between the emissivity of the plate 13 and the amount of radiant heat transfer, and the amount of temperature change received by the temperature sensors 15 and 45 was examined. Here, the amount of change in temperature of the temperature sensors 15 and 45 is calculated assuming that it is proportional to the amount of radiant heat transfer, and the obtained result is the graph of FIG. From this graph, when there is a temperature difference of 0.3 ° C. between the substrate 17 and the temperature control plate 13, the emissivity of the plate 13 required for generating a temperature change of 0.01 ° C. in the temperature sensors 15 and 45. Can be estimated to be about 0.4.
[0047]
However, as described above, the emissivity required for the temperature control plate 13 changes depending on requirements and conditions such as the detection resolution of the temperature sensors 15 and 45 and measurement reproducibility. However, as outlined in the prior art, in order to achieve a position accuracy of 10 nm, the accuracy budget assigned to the temperature factor is considered to require 0.03 ° C. as temperature uniformity, and about 1/10 of 0 The order of 0.001 ° C. is required at least as the measurement resolution of the temperature sensor. Therefore, it is preferable to apply the temperature control plate 13 having an emissivity of 0.4 or more.
[0048]
Next, in order to verify the effects of the present invention, an experiment was conducted on stabilization of the substrate temperature by changing the material of the temperature control plate 13 using the constant temperature vacuum chamber of FIG. Specifically, for the plate A having a small emissivity, a copper plate having a surface cleaned and not coated with an oxide film or the like is used, and for the plate B having a large emissivity, a conductive diamond-like plate is used as the copper plate shown in FIG. A structure on which carbon was formed was used. The emissivity of each of the plates A and B is 0.05 or less and 0.8 or more from the numerical values in the literature, and is not an accurate value because it is not an actual plate value. In general, it is difficult to accurately determine the emissivity of a material, and there are variations in literature values. The numerical values shown here are only a guide.
[0049]
The used apparatus is the electron beam drawing apparatus shown in FIG. 8, and the constant temperature vacuum chamber having the structure shown in FIG. 3 was applied to the first constant temperature vacuum chamber 86 in the figure. As other experimental conditions, the entire apparatus was placed in a clean room at 23 ± 0.5 ° C. to be kept at a constant temperature, and the temperature of each chamber was precisely controlled at 1/100 ° C. to reach the standard 23 ° C. It is set to be.
[0050]
Here, the transfer procedure for the experiment will be outlined with reference to FIG. First, the substrate was set in the preliminary chamber 83 whose temperature was controlled to 23 ° C. in the air atmosphere. As a result, the temperature of the substrate is adjusted to approximately 23 ° C. by heat transfer by the atmospheric gas. After the substrate in this state is transferred to the vacuum preparatory chamber (load lock chamber) 84 by the transfer means (not shown), the substrate is evacuated in a normal sequence, and then the substrate is transferred by the transfer robot (not shown). Is moved to the constant temperature vacuum chamber 85 for a transfer robot, and is transferred to the first constant temperature vacuum chamber 86. The constant temperature vacuum chamber 86 has the configuration of FIG. 4 as described above, and the transported substrate 88 is mounted on the support mechanism. In a series of transport operations, the vacuum / atmosphere is controlled by opening and closing the gate valves 89 and 90 according to a set sequence. By evacuation in the pre-vacuum chamber 84, the temperature of the substrate in the chamber is temporarily lowered by adiabatic expansion, so that the temperature is reduced.
[0051]
Next, since the substrate is transported to the constant temperature vacuum chamber 86 in the temperature lowered state, the substrate is mounted on the support mechanism in a state where there is a temperature difference between the substrate temperature and the set temperature 23 ° C. of the constant temperature vacuum chamber 86. Will be done. In this experiment, a glass substrate having a temperature sensor separately attached to the substrate was used in order to directly measure the temperature of the substrate and evaluate how the substrate temperature was relaxed. When the substrate with the temperature sensor is conveyed to the constant temperature vacuum chamber 86 and mounted on the support mechanism, the terminal of the temperature sensor and the measuring terminal provided in the chamber come into contact with each other to provide a mechanism capable of directly measuring the temperature of the mask substrate. I have. The temperature sensors used at the three locations of the mask, the plate, and the support mechanism are all calibrated platinum resistors (Pt100), and their machine differences are 0.0009 ° C in Mean value and 30009 in 3σ value. It was 0.0016 degreeC (N = 2042, the measurement result for 17 hours).
[0052]
FIG. 6 shows the results of plate A as the results obtained in this experiment. It can be seen that the temperature sensor provided on the surface of the plate A hardly changes in temperature, and the sensitivity of the temperature response is almost zero. It can be seen that a change of about -0.015 ° C. occurs in the temperature sensor built in the support mechanism.
[0053]
FIG. 7 shows the results for plate B. In this case, the emissivity increased, and the temperature change of the temperature sensor on the plate surface occurred at about −0.025 ° C. It is possible to monitor the subsequent temperature relaxation step. The temperature change of the temperature sensor built in the support mechanism is about -0.01 ° C.
[0054]
Comparing the results in both figures, it can be seen that when the emissivity on the plate surface is small, the temperature difference between the substrates cannot be detected by the temperature sensor provided on the plate surface, and when the emissivity is large, it can be sufficiently detected. As shown in FIG. 5, when the emissivity is 0.4 or more, the temperature change amount of the temperature sensor is predicted to increase to 0.01 ° C. or more, so that it is estimated that the sensing accuracy is improved.
[0055]
Here, the target value of the static temperature of the substrate temperature is 23 ° C., for example, if the range of the convergence temperature is the target value ± 0.02 ° C., the initial temperature of plate A is 23.773 ° C. Is 3 hours and 5 minutes, and plate B has an initial temperature of 23.782 ° C. for 2 hours and 10 minutes. Therefore, it can be confirmed that the time required for stabilization is reduced by employing the temperature control plate B having the configuration shown in FIG. 2 as compared with the temperature control plate A made of a single copper plate as in this example. In this example, a time reduction of about 30% is realized.
[0056]
When the stabilization convergence time is determined by the temperature sensor provided on the plate surface, first, the gradient of the temperature change amount of the temperature sensor with respect to the substrate temperature change amount is obtained, and the convergence range of the substrate temperature is determined. It is necessary to determine the convergence range of the temperature sensor corresponding to ± 0.02 ° C. The amount of change in the temperature of the temperature sensor / the amount of change in the substrate temperature is 0.79, and ± 0.016 ° C., which is 0.79 times of ± 0.02 ° C., corresponds to the convergence range of the temperature sensor. Therefore, by monitoring the convergence range of the temperature sensor as 23 ± 0.016 ° C. with respect to the convergence range of the substrate temperature of 23 ± 0.02 ° C., time management can be performed accurately. When the temperature is stabilized when a normal substrate is transported, by monitoring the time course until the temperature change of the temperature sensor provided on the plate surface converges to 23 ± 0.016 ° C., It is possible to accurately grasp the completion point of the temperature stabilization of the substrate.
[0057]
(Fourth embodiment)
In this embodiment, in FIG. 8, an electron beam writing apparatus in which the constant temperature vacuum chamber 86 and the second constant temperature chamber 87 are applied with the constant temperature vacuum chamber having the configuration of FIG. The temperature stabilization process will be described.
[0058]
First, a plurality of substrates were set in the preliminary chamber 83 whose temperature was controlled to 23 ° C. in the air atmosphere. In the present embodiment, the substrate is mounted on a substrate carrier and placed in a locally cleaned pod, so that the temperature of the substrate is adjusted to approximately 23 ° C. by heat transfer by atmospheric gas. After the first substrate in such a state was transferred to the pre-vacuum chamber (load lock chamber) 84 by the transfer means (not shown), evacuation was performed in a normal sequence. Next, the substrate is moved to a constant temperature vacuum chamber 85 for a transfer robot by a transfer robot (not shown) and transferred to a first constant temperature vacuum chamber 86. The constant temperature vacuum chamber 86 has the configuration of FIG. 1 as described above, and the transported substrate 88 is mounted on the support mechanism.
[0059]
Similarly, the second substrate is conveyed from the preliminary chamber 83 through the vacuum preparatory chamber (load lock chamber) 84 and is conveyed to the second constant temperature chamber 87. In a series of transfer operations, the vacuum / atmosphere is controlled by opening and closing the gate valves 89 and 90 according to a set sequence, and the drawing order of the substrates is also defined. On the way, the temperature of the substrate, which has been lowered by the vacuum evacuation in the vacuum preparatory chamber 84, is set to 23 ° C., which is the environmental temperature of the drawing chamber 81, in the first constant temperature vacuum chamber 86 and the second constant temperature vacuum chamber 87. Then, the temperature is stabilized in a predetermined convergence temperature range.
[0060]
Next, the first substrate is taken out of the first constant temperature vacuum chamber 86, and the gate valve 91 is opened to carry the substrate to the drawing stage 82 of the drawing chamber 81 and mounted. At the time of mounting, since the substrate temperature has already been stabilized to the temperature required for the writing position accuracy, there is no need to wait for the temperature to be stabilized at the writing stage 82, and the operation related to writing with the electron beam is immediately performed. Is started. Therefore, a decrease in throughput does not occur.
[0061]
Next, the first substrate after the drawing is unloaded, and when drawing the second substrate, the temperature of the second substrate is already stabilized during the drawing time of the first substrate. Therefore, the wafer is immediately transferred to the drawing chamber and the drawing operation is started. As in the present embodiment, by stabilizing the substrate temperature in a plurality of constant temperature vacuum chambers, the throughput can be further improved and high-precision drawing can be realized.
[0062]
(Modification)
Note that the present invention is not limited to the above embodiments. Although one temperature sensor is used on the temperature control plate used in the embodiment, a plurality of temperature sensors can be arranged in the plane. In this case, temperature stabilization can be performed including temperature uniformity. Although the copper plate is used as the base material of the temperature control plate, a metal or alloy such as aluminum or nickel can be applied. In the embodiment, conductive diamond-like carbon is used as a coating material on the temperature control plate. However, it is sufficient that carbon is included as a composition and the conductive material has conductivity, and graphite, C60, carbon The present invention can be applied to a laminated structure of a film or a mixed material containing carbon as long as the conditions are satisfied. The coating surface does not necessarily have to be on both sides of the plate, but may be only coated on the surface side facing the substrate, and may be a structure in which a part is formed instead of the entire surface.
[0063]
In addition, although a water flow pipe is built in as a temperature control mechanism of the temperature control plate, a structure in which another structure in which the pipes are integrated are connected from the back side of the plate to maintain the temperature can be applied. In all the embodiments, the temperature control plate is set below the substrate, but it is sufficient that the temperature control plate is opposed to the substrate, and may be installed above or on both sides. Further, the embodiment in which the temperature is compensated for the temperature decrease of the substrate due to the evacuation has been described. When the substrate temperature is different from the desired temperature due to the influence or the temperature change of the installation environment before the transfer, the present invention is applied to compensate the temperature, improve the throughput, and perform high-precision drawing. Needless to say, it is feasible.
[0064]
In addition, monitoring of the output of the temperature sensor by the temperature measurement unit is basically desirably always performed. However, since the temperature change of the substrate and the temperature control plate is not so fast, even if the monitoring is performed intermittently, it is substantially required. No effect is expected. In the embodiment, an example in which the present invention is applied to an electron beam drawing apparatus is described. However, the present invention is a method effective when drawing a pattern in a vacuum, and can be applied to an ion beam drawing apparatus. In addition, various modifications can be made without departing from the scope of the present invention.
[0065]
【The invention's effect】
As described above in detail, according to the present invention, the temperature control of the substrate is quickly performed by using a temperature control plate facing the substrate having a high thermal conductivity and a high emissivity, and a temperature sensor is provided on the temperature control plate. By attaching the sensor, the response of the temperature change due to the radiation from the substrate can be monitored with high sensitivity and high accuracy. By realizing this high-precision monitoring, the stabilization time for stabilizing the temperature of the substrate that has fluctuated due to evacuation can be reduced, and both throughput and drawing accuracy can be achieved. It can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a constant temperature vacuum chamber used in a charged beam drawing apparatus according to a first embodiment.
FIG. 2 is a sectional view showing a configuration of a temperature control plate installed in the constant temperature vacuum chamber of FIG.
FIG. 3 is a schematic configuration diagram showing a constant temperature vacuum chamber used in a charged beam drawing apparatus according to a second embodiment.
FIG. 4 is a schematic configuration diagram showing a constant-temperature vacuum chamber used in a charged beam drawing apparatus according to a third embodiment.
FIG. 5 is a view showing analysis data in a third embodiment.
FIG. 6 is a view showing experimental data in the third embodiment.
FIG. 7 is a view showing experimental data in the third embodiment.
FIG. 8 is a diagram showing the overall configuration of an electron beam writing apparatus.
[Explanation of symbols]
11 ... constant temperature vacuum chamber
12 ... Support mechanism
13 ... Temperature control plate
14. Temperature control mechanism
15, 35, 45, 46 ... temperature sensor
16. Temperature measurement means
17 ... Substrate to be drawn
21 ... Plate base material
22 ... Coating film
23… Piping
81… Drawing room
82 ... Drawing stage
83 ... Reserve room
84… vacuum spare chamber (load lock chamber)
85… Constant temperature vacuum chamber for transfer robot
86: first constant temperature vacuum chamber
87: second constant temperature vacuum chamber
88: Substrate to be drawn
89, 90, 91 ... gate valve

Claims (4)

The substrate to be drawn used for charged beam writing is preliminarily kept at a constant temperature in a constant temperature vacuum chamber, the substrate at constant temperature is transferred into the drawing chamber, and a desired pattern is drawn on the substrate in the drawing chamber by a charged beam drawing method. So,
In the constant temperature vacuum chamber, a support mechanism for supporting the substrate, and disposed above or below or both of the support mechanism so as to face the substrate, and has an area equal to or greater than the substrate and 100 W / mK or more. A temperature control plate comprising a structure coated with a conductive carbon-containing material having a heat transfer coefficient and a surface having an emissivity of 0.4 or more, and a temperature control device for controlling the temperature of the temperature control plate. An adjusting mechanism and a temperature sensor arranged on the surface or inside of the temperature control plate to detect the temperature of the plate are provided,
By constantly or intermittently monitoring the detection output of the temperature sensor, the temperature change occurring in the temperature control plate due to the substrate being transported into the constant temperature vacuum chamber or being mounted on the support mechanism is described. A charged beam writing method, comprising: detecting the temperature and stabilizing the substrate temperature by leaving the substrate in the constant temperature vacuum chamber until the temperature change converges to a predetermined range. The charged beam drawing method according to claim 1, wherein a temperature sensor made of a platinum resistor having a temperature measurement resolution of 0.001 ° C or less is used as the temperature sensor. The substrate to be drawn used for charged beam writing is preliminarily kept at a constant temperature in a constant temperature vacuum chamber, the substrate at constant temperature is transferred into the drawing chamber, and a desired pattern is drawn on the substrate in the drawing chamber by a charged beam drawing method. So,
In the constant temperature vacuum chamber, a support mechanism for supporting the substrate, and disposed above or below or both of the support mechanism so as to face the substrate, and has an area equal to or greater than the substrate and 100 W / mK or more. A temperature control plate comprising a structure having a heat transfer coefficient and having a surface coated with a conductive carbon-containing material having an emissivity of 0.4 or more; and a temperature for controlling the temperature of the temperature control plate. An adjusting mechanism and a temperature sensor arranged at a substrate contact portion of the support mechanism to detect a temperature of the substrate,
By constantly or intermittently monitoring the detection output of the temperature sensor, a temperature change generated when the substrate is transferred into the constant temperature vacuum chamber or mounted on the support mechanism is detected, and the temperature change is detected. A charged beam writing method, wherein the substrate is allowed to stabilize by leaving the substrate in the constant temperature vacuum chamber until the change converges to a predetermined range. By actively controlling the temperature of the temperature control plate based on the detection output of the temperature sensor, the temperature of the substrate is stabilized more quickly than when the temperature of the temperature control plate is controlled to be constant. The charged beam drawing method according to claim 1.

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