JP2023148841A - Exposure apparatus, method for adjusting exposure apparatus, and article manufacturing method - Google Patents

Abstract

To provide a technique advantageous for reducing haze of an optical element in a projection optical system while suppressing a flow rate consumption of supplied gas.SOLUTION: An exposure apparatus that exposes a substrate has: a holding part holding the substrate; a projection optical system which projects an image of a pattern on the original plate onto the substrate held by the holding part; a supply part which supplies gas into a space between the projection optical system and the substrate held by the holding part; and a control part which controls supply of gas by the supply part on the basis of information on haze of an optical element in the projection optical system opposing to the substrate held by the holding part.SELECTED DRAWING: Figure 1

Description

The present invention relates to an exposure apparatus, an exposure apparatus adjustment method, and an article manufacturing method.

2. Description of the Related Art As one of the apparatuses used in the manufacturing process (lithography process) of liquid crystal panels, semiconductor devices, etc., there is an exposure apparatus that projects a pattern of an original illuminated by an illumination optical system onto a substrate to expose the substrate. When an exposure apparatus exposes a resist (photosensitive material) coated on a substrate, contaminants can be generated from the resist. Contaminants cloud the optical element located around the substrate by reacting with impurities such as acids, bases, and organic substances in the surrounding atmosphere and on the surface of the optical element. An optical element disposed at the lowest end of the projection optical system and exposed to the space between the projection optical system and the substrate so as to face the substrate is particularly susceptible to fogging.

Moreover, the contaminants that cloud the optical elements located at the bottom of the projection optics do not come only from the resist. There are drive systems and structures around the projection optical system that use grease and adhesives that easily generate contaminants, and parts themselves that use resins and rubber that easily generate contaminants. . The contaminants generated from these are carried around the substrate by the airflow of the air conditioner, reach the optical element disposed at the lowest end of the projection optical system, and cloud the optical element.

Clouding of the optical element can cause deterioration in pattern transfer performance due to insufficient exposure, uneven illuminance, flare, etc. For this reason, some exposure apparatuses have an air nozzle disposed near the optical element to blow away the contaminants. When blowing away contaminants with an air nozzle, it is generally advantageous to flow the gas at high velocity throughout the space between the substrate and the optical element, and use a large flow of clean gas, e.g. clean dry air, nitrogen gas. It is preferable to use .

Patent Document 1 discloses a configuration in which gas is flowed into a space between a substrate and an optical element at a flow rate substantially higher than the supply flow rate. In Patent Document 1, a gas supply port is provided outside the projection optical system, and a baffle plate is arranged to guide the gas blown out from the gas supply port into the space between the substrate and the optical element. This baffle plate generates a Coanda effect and guides the gas into the space between the substrate and the optical element while drawing in the surrounding gas, increasing the flow rate. A configuration is disclosed in which a rectifying mechanism is provided to increase the flow velocity on the substrate side by narrowing the flow path, and blows off gas containing contaminants generated from the resist. In Patent Document 2, contaminants are blown away not in the entire space between the substrate and the optical element but in a local area, thereby preventing the contaminants from reaching the optical element while suppressing consumption of gas flow rate.

Japanese Patent Application Publication No. 2005-333152 Japanese Patent Application Publication No. 2018-045167

However, if clean gas is simply flowed at high speed to protect the optical elements from contaminants, the gas around the projection optical system will be engulfed by the clean gas, and the contaminants will be carried around the substrate. The contaminants then reach the lowest optical element of the projection optical system and cloud the optical element. In particular, when the gas is concentrated on the lens surface or substrate surface to prevent contaminants from reaching the optical elements while maintaining a high wind speed, surrounding gases and even contaminants may contaminate those areas. can even become entangled and increase fogging of the optical element. On the other hand, if clean gas is allowed to flow at a low speed, it is possible to prevent contaminants from being drawn into the vicinity of the projection optical system, but it is difficult to prevent contaminants from reaching the optical elements from the resist. However, when flowing clean gas throughout the space in order to prevent fogging caused by contaminants around the substrate and from contaminants from the resist, the flow rate is too high and the gas is forced to flow at high speed. things become difficult.

In view of the above problems, the present invention provides an advantageous technique for reducing fogging of optical elements of a projection optical system while suppressing flow rate consumption of supply gas.

According to one aspect of the present invention, there is provided an exposure apparatus that exposes a substrate, comprising: a holding section that holds the substrate; and a projection optical system that projects an image of a pattern of an original onto the substrate held by the holding section. , a supply unit that supplies gas to a space between the projection optical system and the substrate held by the holding unit, and fogging of an optical element in the projection optical system facing the substrate held by the holding unit. An exposure apparatus is provided, comprising: a control section that controls the supply of gas by the supply section based on the information of the exposure apparatus.

According to the present invention, it is possible to provide an advantageous technique for reducing fogging of optical elements of a projection optical system while suppressing flow rate consumption of supply gas.

FIG. 1 is a diagram showing a main part configuration of an exposure apparatus in a first embodiment. FIG. 1 is a diagram showing a main part configuration of an exposure apparatus in a first embodiment. FIG. 3 is a diagram of the projection optical system and the first supply unit viewed from below. The figure which shows an example of how an optical element clouds. A diagram showing an example of a cloudy pattern. A diagram showing an example of a cloudy pattern. A diagram showing an example of a cloudy pattern. FIG. 7 is a diagram showing the configuration of an exposure apparatus in a second embodiment. A diagram showing an example of a cloudy pattern. A diagram showing an example of a cloudy pattern. A diagram showing an example of a cloudy pattern. A diagram showing an example of a cloudy pattern. FIG. 7 is a diagram showing the configuration of main parts of an exposure apparatus in a third embodiment. FIG. 7 is a diagram showing the main part configuration of an exposure apparatus in a fourth embodiment. FIG. 1 is a diagram showing the overall configuration of an exposure apparatus.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the claimed invention. Although a plurality of features are described in the embodiments, not all of these features are essential to the invention, and the plurality of features may be arbitrarily combined. Furthermore, in the accompanying drawings, the same or similar components are designated by the same reference numerals, and redundant description will be omitted.

<First embodiment>
FIG. 1 is a diagram showing the main part configuration of an exposure apparatus 100 in the first embodiment. In this specification and the drawings, directions are shown in an XYZ coordinate system in which the horizontal plane is the XY plane. The substrate stage 4, which will be described later, holds the substrate W on the holding surface of the substrate stage 4 so that the surface of the substrate W is parallel to a horizontal plane (XY plane). Therefore, hereinafter, directions perpendicular to each other within a plane along the holding surface of the substrate stage 4 will be referred to as the X-axis and the Y-axis, and a direction perpendicular to the X-axis and the Y-axis will be referred to as the Z-axis. Further, hereinafter, directions parallel to the X axis, Y axis, and Z axis in the XYZ coordinate system are referred to as the X direction, Y direction, and Z direction, respectively.

The exposure apparatus 100 is an exposure apparatus that exposes a substrate W, and includes a substrate stage 4 as a holding section that holds the substrate W, and an image of a pattern of an original (not shown) on the substrate W held by the substrate stage 4. and a projection optical system 2 for projecting images. In addition, the exposure apparatus 100 may also include a mechanism for holding the original, an illumination optical system for illuminating the original, etc., but these are not shown here. The exposure apparatus 100 also includes a control section 23 that controls each section of the exposure apparatus 100. The control unit 23 is constituted by a computer including, for example, a CPU (processor) and a memory, and is electrically connected to each part in the device and controls each part in an integrated manner. Note that the control unit 23 may be installed in a location other than the room in which the exposure apparatus 100 is installed (for example, a clean room), and may be realized as a server device connected to the exposure apparatus 100 via a wired or wireless network. .

The projection optical system 2 may include a plurality of optical elements such as lenses, glass plates, etc., but particularly includes an optical element 3 arranged at the lowermost end, as shown in FIG. During exposure, the optical element 3 is exposed in the space between the projection optical system 2 and the substrate W so as to face the substrate W held by the substrate stage 4.

The exposure apparatus 100 includes a first supply section 10 that supplies a first gas 40 to a space S between a substrate W placed on a substrate stage 4 and an optical element 3 of the projection optical system 2 . The first supply unit 10 includes a gas supply port 11 that blows out the first gas 40 toward the space S, and a flow rate adjustment unit 20 that adjusts the flow rate of the gas blown out from the gas supply port 11. The gas supply port 11 may be called a blowout port, and may be formed as an opening or a nozzle. Further, the first supply section 10 may also have a rectification mechanism 12. The rectifying mechanism 12 has a first opening 12a located far from the exposure center and a second opening 12b located close to the exposure center. The rectifying mechanism 12 is used for at least one of adjusting the flow of the wind around the first supply unit 10 in a certain direction, preventing surrounding wind from being drawn in, and adjusting the direction in which the surrounding wind is drawn. It is installed and is not essential to the first supply section 10.

FIG. 2 shows a modification of the configuration of the exposure apparatus 100 shown in FIG. 1. In FIG. As shown in FIG. 2, the gas supply port 11 of the first supply section 10 may be configured to be larger than that in FIG. Note that in FIG. 1, the second opening 12b is arranged directly below the optical element 3, and in FIG. 2, the gas supply port 11 is arranged immediately below the optical element 3. However, they may also be arranged outside the projection optical system 2, from which gas is supplied into the space S between the optical element 3 and the substrate stage 4.

FIG. 3 shows a diagram of the projection optical system 2 and the first supply section 10 viewed from below. As shown in FIG. 3, the size of the gas supply port 11 in the direction (X direction) perpendicular to the blowing direction of the first gas 40 is preferably larger than the irradiation range 61 of the laser light (exposure light). More preferably, it is larger than the range 62 through which the laser beam passes through the first surface 31 of the optical element 3 on the substrate W side.

The first gas 40 is preferably a clean gas so as not to cloud the optical element 3. A clean gas means a gas that contains few impurities such as acids, bases, and organics. More preferably, the clean gas is air obtained by removing impurities such as acids, bases, and organics from air called clean air, a gas obtained by drying clean air called clean dry air, or an inert gas such as nitrogen gas. Preferably gas.

The second supply section 5 that supplies the second gas 41 is also arranged in the space where the first supply section 10 is arranged. As shown in FIGS. 1 and 2, the gas supply port 11 is arranged between the second supply section 5 and the projection optical system 2. The second supply unit 5 may be understood to be equipment that air-conditions a chamber or clean room (not shown) that accommodates the substrate stage 4 and the projection optical system 2. The second supply section 5 may be included in the exposure apparatus 100, but it does not need to be. A part of the second gas 41 supplied from the second supply unit 5 passes through the space between the optical element 3 and the substrate stage 4 (substrate W).

The second supply section 5 includes a chemical filter 6, and the second gas 41 is kept in a clean state by the chemical filter 6. A clean state regarding the second gas 41 means that the chemical filter 6 maintains a state in which impurities such as acids, bases, and organics are kept low. However, since the chemical filter 6 deteriorates over time, it is not possible to maintain the second gas 41 in a clean state semi-permanently. Furthermore, if the source of the second gas 41 in the second supply section 5 is the air of the clean room in which the exposure apparatus 100 is arranged, even if it passes through the chemical filter 6, the cleanliness of the second gas 41 is as follows. It may also depend on the cleanliness of the clean room. In addition, if the cleanliness of the clean room is poor, the rate of deterioration of the chemical filter 6 may be accelerated.

Moreover, impurities may be mixed into the second gas 41 while passing through the space S between the optical element 3 and the substrate stage 4 (substrate W). Impurities may include acids, bases, organic impurities, etc. generated from adhesives and greases used in actuators, guides, bearings, etc. for driving the substrate stage 4. Further, impurities may include acids, bases, organic impurities, etc. generated from resins, rubbers, etc. of structures, mounting objects, etc. Therefore, it is difficult to maintain the second gas 41 in a clean state. Furthermore, when the gas in the space where the first supply unit 10 is arranged is circulated and passed through the chemical filter 6 to become the second gas 41, it is also affected by contaminants 50 generated from the resist of the substrate W, which will be described later. As a result, the rate of deterioration of the chemical filter 6 further accelerates. Therefore, even in such a case, it becomes difficult to keep the second gas 41 in a clean state.

As described above, the second gas 41 loses its clean state over time. Therefore, one of the roles of the first supply unit 10 is to prevent the second gas 41 that is no longer in a clean state from reaching the optical element 3.

Next, clouding that occurs in the optical element 3 when the exposure apparatus irradiates the substrate W with laser light via the projection optical system 2 (that is, when the substrate W is exposed) will be described. When the substrate W is irradiated with laser light, contaminants 50 are generated from the substrate W. This is because the substrate W is coated with a resist, and contaminants 50 are generated from the resist upon exposure. The contaminants 50 are impurities such as acids, bases, and organic substances. The contaminant 50 includes a component that is generated with a vertically upward velocity, reaches the optical element 3 via the second gas 41 or the first gas 40, and clouds the optical element 3. Therefore, one of the roles of the first supply section 10 is to prevent this contaminant 50 from reaching the optical element 3.

As described above, there are two main factors that cause the optical element 3 to become cloudy. The first factor is contaminants 50 coming from directly below the optical element 3. The second factor is a contaminant (impurity) other than the contaminant 50. This mainly mixes with gas from outside the space S. For example, the hot spring substance is mixed with the second gas 41 coming from around the optical element 3 and transported.

Usually, the rate of clouding due to the first factor is faster than the rate of clouding due to the second factor. Therefore, the flow rate of the first gas 40 supplied from the first supply unit 10 of the first embodiment is set to be higher than that of the second gas 41 so that the contaminants 50 can be blown away. However, the components of the resist applied to the substrate W vary depending on the usage conditions of the exposure apparatus, and there are cases where more contaminants 50 are generated than expected and cannot be blown away. Further, for example, the cleanliness of the clean room may be poor and the second gas 41 may be contaminated, or the chemical filter 6 may deteriorate early. In such a case, even if the contaminants 50 can be blown away by the first gas 40, the second gas 41 may reach the optical element 3 through the paths 41a, 42b, or 43c shown in FIGS. Therefore, the optical element 3 becomes cloudy. As described above, at the stage when the flow rate of the first supply unit 10 is set, it may not be possible to predict the progress of clouding, and it is difficult to set an appropriate flow rate for clouding.

To deal with such problems, in one embodiment, the control unit 23 controls the first supply unit 10 based on information on cloudiness of the optical element 3 of the projection optical system 2 facing the substrate W held by the substrate stage 4. may be configured to control the supply of gas by. Alternatively, in one embodiment, a method for adjusting the exposure apparatus 100 is performed. The adjustment method may include a step executed by the control unit 23, or may include a step executed by the user (operator). In one example, the adjustment method includes a step of specifying a cloudy pattern of the optical element 3 arranged to face the substrate W, and a space S between the substrate W and the optical element 3 according to the specified cloudy pattern. The method may include a step of adjusting the flow rate or flow rate of the first gas 40 supplied to the first gas 40 . Hereinafter, such an adjustment method will be explained in detail.

First, the cloudy pattern will be explained in detail. In this embodiment, the cloudy information includes positional information of the cloudy on the surface of the optical element 3, and the positional information is represented as a cloudy pattern as shown below.

FIG. 4 shows typical examples of a cloudy position 42 caused by the second gas 41 and a cloudy position 51 caused by the pollutant 50. FIG. 4 is a view of the first surface 31 of the optical element 3 viewed from below the projection optical system 2. As shown in FIG. 4, the cloudy position 42 caused by the second gas 41 is located around the first surface 31 of the optical element 3. The cloudy position 51 caused by the contaminant 50 is located at the center of the first surface 31 or on the downstream side in the flow direction of the first gas 40 . The reason for this is that the second gas 41 is drawn in from all directions from the interface with the first gas 40 blown out from the first supply section 10 in the direction of the first gas 40, diffused, and mixed, and the optical element This is because there is a tendency to reach 3. In the case of the contaminant 50, the traveling direction of the generated contaminant 50 tends to be vertically upward, and this is because the contaminant 50 continues to travel vertically upward and reaches the optical element 3. That is, by checking whether the cloudiness on the first surface 31 of the optical element 3 is at the cloudy position 42 or the cloudy position 51, it is possible to determine whether the cloudiness is caused by the second gas 41 or the contaminant 50. It is possible to determine whether Based on the determination result, fogging can be reduced by adjusting the flow rate adjustment section 20 according to the following procedure.

First, as a first step, a first initial flow rate of the first supply section 10 is set. If the first supply unit 10 has been used up to this point, the flow rate set at that time may be set as the first initial flow rate. Furthermore, from past experience, if it is possible to predict whether the current cloudiness of the optical element 3 is caused by the second gas 41 or the contaminant 50, then the first initial flow rate can be calculated as follows. may be set. For example, if it is predicted that the second gas 41 is the cause, the first initial flow rate of the first supply section 10 is set to a ratio of 1.5 to 1.5 to the ratio of the flow velocity of the first gas 40 and the flow velocity of the second gas 41. It may be set to 2. If cloudiness is predicted to be caused by the contaminant 50, the first initial flow rate of the first supply unit 10 may be set so that the flow rate of the first gas 40 is faster than the flow rate of the second gas 41. . For example, the first initial flow rate may be determined such that the flow rate of the first gas 40 is twice or more than the flow rate of the second gas 41. If it is known from experience that a faster flow rate of the first gas 40 is better, the first initial flow rate is set so that the flow rate of the first gas 40 is three times the flow rate of the second gas 41. may be determined. Alternatively, the first initial flow rate may be determined such that the flow rate of the first gas 40 is ten times or more greater than the flow rate of the second gas 41. Usually, haze caused by contaminants 50 can have a more serious impact on exposure performance. Therefore, in the following explanation, it is assumed that the first initial flow rate of the first supply unit 10 is set so that the flow rate of the first gas 40 is twice or more faster than the flow rate of the second gas 41.

Next, as a second step, the cloudy pattern on the first surface 31 is checked. The frequency of checking for cloudiness may be, for example, every few months. A detailed example of the frequency will be described later. An example of how to check the cloudy position will also be described. The first method is for the user to visually check the first surface 31 of the optical element 3. The confirmation may be made within the exposure apparatus or by removing the optical element 3. The second method is to check using measuring equipment. The optical element 3 is removed, and the reflectance and transmittance are measured and confirmed using a measuring device. Third, it may be confirmed from information related to measurement results of flare and illuminance using laser light in the exposure apparatus, and information related to exposure accuracy, such as variations in exposure line width. Other methods may be used as long as the cloudy position or information from which the cloudy position can be estimated can be confirmed.

Next, the third procedure will be explained. As an example of the third procedure, first, a case where the cloudy position 42 is cloudy will be described. In other words, the cloudiness is caused by the second gas 41. In order to reduce clouding caused by the second gas 41, the difference in flow velocity between the first gas 40 and the second gas 41 must be small so that the second gas 41 is difficult to be caught up in or mixed with the first gas 40. It is necessary to adjust the flow rate of the first gas 40 so that it becomes the same. If the difference in flow velocity between the first gas 40 and the second gas 41 becomes smaller, the flow of the wind becomes closer to laminar flow, so the second gas becomes less likely to be dragged into or mixed with the first gas 40. Specifically, in the first embodiment, when the optical element 3 is clouded at the cloudy position 42, the first initial flow rate of the first supply unit 10 is set such that the flow rate (flow velocity) of the first gas 40 is small. The flow rate adjustment unit 20 is adjusted so that the flow rate decreases. Thereby, fogging caused by the second gas 41 can be reduced. The flow rate of the first supply unit 10 after this flow rate adjustment is defined as a second initial flow rate.

Here, the amount of change that reduces the first initial flow rate will be explained. The amount of change here may be a fixed value (for example, -10%). Preferably, the distance between the substrate W and the first surface 31, the cloudy position 42, the flow velocity of the first gas 40, the difference in flow velocity between the first gas 40 and the second gas 41, and the effective distance of the first surface 31 through which the laser beam passes From the range, how much the second gas 41 is involved and reaches the first surface 31 is calculated. Then, based on the calculation result, the amount of change to reduce the first initial flow rate is determined depending on how much the degree of fogging of the first surface 31 is desired to be reduced with respect to the period. For example, when it is desired to reduce the degree of fogging to 1/2, it is preferable to adjust the flow rate of the first gas 40 so that the entrainment of the second gas 41 becomes 1/2. However, it is not preferable to adjust from the beginning so that the difference in flow velocity between the first gas 40 and the second gas 41 becomes zero from the initial flow rate. At the initial stage, the flow rate of the first gas 40 suitable for clouding caused by the pollutants 50 is unknown, so if the flow rate of the first gas 40 is made extremely small, the clouding caused by the pollutants 50 may rapidly progress. This is because of their gender. In addition, at the initial stage, although there is a way to determine a preferable amount of change, there is no need to worry too much because the flow rate will naturally approach the optimal value as the procedure continues.

Subsequently, as a fourth step, after a predetermined period of time, the user checks the cloudy pattern. At this time, it is assumed that the cloudiness at the cloudy position 42 has worsened.

In that case, in the fifth step, the flow rate adjustment unit 20 adjusts the second initial flow rate to be small, as in the third step. The flow rate after this adjustment is defined as the third initial flow rate. Further, in this case, the adjustment amount of the flow rate adjustment unit 20 may be determined by calculating the adjustment magnification based on the relationship between the amount by which clouding has progressed from the previous time to the current time and the amount adjusted last time by the flow rate adjustment unit 20.

Next, in the same way as the second and fourth steps described above, after a predetermined period of time, the cloudy pattern is confirmed in the sixth step, and the seventh step is carried out in the same way as the third and fifth steps. to adjust the flow rate. The above sequence of steps is repeatedly executed.

On the other hand, a case where the cloudy position 51 is cloudy when the cloudy pattern is checked will be described, although any stage is acceptable. In other words, this is a response to cloudiness caused by the pollutant 50. Here, another example of the above-mentioned third procedure will be explained.

In order to reduce the cloudiness caused by the contaminants 50, it is necessary to blow the contaminants 50 out with the first gas 40 blown out from the first supply section 10 so as to overcome the vertical upward movement of the contaminants 50. Therefore, by increasing the flow rate and velocity of the first gas, the contaminants 50 can be blown away. In the example of FIG. 4, the cloudy position 51a is located at the center of the first surface 31, and almost no contaminants 50 can be washed away. However, if the flow rate (flow velocity) of the first gas 40 allows it to be pushed away somewhat, the first gas 40 may move in the downstream direction, as in the cloudy position 51b. In the first embodiment, when the cloud is at the cloudy position 51, the flow rate adjustment unit 20 is adjusted so that the flow rate (flow velocity) of the first gas 40 becomes large, that is, the first initial flow rate becomes large. By adjusting this, cloudiness caused by the pollutants 50 can be reduced. The flow rate of the first supply unit 10 after this flow rate adjustment is defined as a second initial flow rate.

Here, the amount of change that increases the first initial flow rate will be explained. The amount of change here may be a fixed value (for example, +50%). Preferably, from the distance between the substrate W and the first surface 31, the cloudy position 51, and the flow rate of the first gas 40, a change in the position of the cloudy position 51 when the flow rate of the first gas 40 is increased is calculated, It is preferable to determine the amount of change in the first initial flow rate. For example, in this case, if it is possible to predict the particle size, initial velocity, and flow rate of the pollutants 50 ejected vertically, the amount of change in the position of the cloudy position 51 can be calculated. . Then, the amount of change to increase the first initial flow rate may be determined so that the cloudy position 51 is outside the effective range through which the laser beam of the first surface 31 passes. However, if such a physical quantity is difficult to predict, the flow velocity of the first gas 40 or The amount of change may be determined by assuming that the cloudy position 51 changes in proportion to the square. In addition, at the initial stage, although there is a way to determine a preferable amount of change, there is no need to worry too much because the flow rate will naturally approach the optimal value as the procedure continues.

Subsequently, as a fourth step, after a predetermined period of time, the user checks the cloudy pattern. At this time, it is assumed that the cloudiness at the cloudy position 51 has worsened.

In that case, in the fifth step, the flow rate adjustment unit 20 adjusts the second initial flow rate to increase it, similarly to the third step. The flow rate after this adjustment is defined as the third initial flow rate. Further, in this case, the adjustment amount of the flow rate adjustment unit 20 may be determined by calculating the adjustment magnification based on the relationship between the amount by which clouding has progressed from the previous time to the current time and the amount adjusted last time by the flow rate adjustment unit 20.

Subsequently, as in the procedure described above, after a predetermined period of time, the cloudy pattern is confirmed (specified) in the sixth step, and the flow rate or flow rate of the gas supplied to the space S is adjusted in the seventh step. The above sequence of steps is repeatedly executed.

In the above-mentioned series of steps, the case where a certain type of clouding progresses has been explained, but depending on the progress of the clouding caused by the second gas 41 and the clouding caused by the contaminant 50, a procedure that combines them may be used to 40 flow rates may be adjusted.

Here, the cloudy position 42 and the cloudy position 51 will be explained in detail. The cloudiness in the optical element 3 is not cloudy at a single point, but cloudy over a certain range. For example, when determining that the first surface 31 is cloudy at the cloudy position 42, the cloudy position 42 is the most cloudy part of the first surface 31, that is, the part where the most pollutants are attached. It may be a place. For example, as shown in FIG. 4, the control unit 23 calculates the center of gravity of a convex portion on a curve (determination value profile) showing the relationship between the first surface 31 and the degree of cloudiness (determination value), and may be specified as the cloudy position 42, which is the most cloudy position. The cloudy position 51 can also be determined in the same manner. Further, the main cause can be determined based on the cloudy position 42 and the cloudy position 51, but in reality, the wind flow may be complicated, and cloudy weather is not 100% determined as one of the factors. However, the countermeasures will depend on the cloudy position.

An example of a method for checking the cloudy position will be explained. The first method is to visually check the first surface 31 of the optical element 3. The confirmation may be made within the exposure apparatus or by removing the optical element 3. The second method is to check using a measuring device. Remove the optical element 3 and measure and confirm the reflectance and transmittance. Third, it may be confirmed from information related to exposure precision, such as information related to measurement results of flare and illuminance using laser light in the exposure apparatus, and variation in exposure line width. Other methods may be used as long as the cloudy position or information from which the cloudy position can be estimated can be confirmed.

The timing of checking the cloudy position and the timing of adjusting the flow rate will be explained. The exposure apparatus does not become unusable even if the optical element 3 becomes cloudy even slightly. It is possible to determine a threshold level of cloudiness at which it becomes difficult to use the exposure apparatus. To give an example of the period until the cloudiness threshold is exceeded, it may be very short, for example, 12 months, or long, for example, 36 months or more. However, these are just examples, and differ depending on the usage situation of the exposure apparatus.

Further, as cloudiness progresses, cloudiness may start to progress rapidly. From this point of view, when the amount of contaminants is unknown, such as when the resist of the substrate W is changed to an unknown one at the start of operation of the exposure equipment, or when the environment of the clean room is changed, If there is a possibility that the amount of clouding may change, the rate of progress of clouding is unknown. In such a case, it is better to check the cloudy position and adjust the flow rate after, for example, two weeks to one month. By doing so, it is possible to take measures against the causes of cloudy weather at an early stage of the progress of cloudy weather. As a result, the progress of fogging can be stopped or slowed down at an early stage.

On the other hand, if the progress of clouding is stable, the position of the clouding can be checked every 1 to 2 months and the flow rate can be adjusted. However, if the exposure apparatus is used in an environment where there are strict restrictions on the progression of clouding, it is preferable to check for clouding and adjust the flow rate in a shorter period than the above-mentioned period.

As described above, the flow rate of the first gas 40 can be adjusted depending on the cloudy position. The control unit 23 can control the flow rate of the airframe from the first supply unit 10 with respect to the flow rate of the gas from the second supply unit 5 by controlling the flow rate adjustment unit 20 based on the cloudy information. Below, examples of adjusting the flow rate (flow velocity) of the first gas 40 will be explained for various examples of cloudy patterns shown in FIG. 5. Note that, as explained in connection with the above series of procedures, the flow rate (flow rate) of the first gas 40 is assumed to be larger than the flow rate (flow rate) of the second gas 41 in the initial state.

If the cloudy pattern is a pattern shown in any of FIGS. 5(A), (B), (C), (D), FIG. It is determined that the main cause of this is the second gas 41 passing through the paths 41a, 41b, and 41c shown in FIGS. 1 to 3. In particular, in the case of FIG. 5(D), it is determined that the influence of the entrainment of the second gas 41 passing through the path 41a is large. In these cases, the difference in flow velocity between the first gas 40 and the second gas 41 should be reduced so that the second gas 41 is not dragged into the first gas 40 or is difficult to mix. Therefore, in this case, the flow rate adjustment unit 20 is adjusted to reduce the flow rate (flow velocity) of the first gas 40. However, it should be noted that the influence of cloudiness caused by the pollutant 50 is not zero.

When the cloudy pattern is shown in any one of FIGS. 7(A), (B), (C), and (D), it is determined that the main cause of the clouding is the pollutant 50. Therefore, in this case, the flow rate adjustment unit 20 is adjusted to increase the flow rate (flow velocity) of the first gas 40.

In addition, when cloudiness does not occur, the flow rate (flow rate) of the first gas 40 at the cloudy pattern confirmation timing is adjusted to be lowered using the flow rate adjustment unit 20, or the flow rate (flow rate) is maintained.

The flow rate adjustment methods for various cloudy patterns have been described above, but for complex cloudy patterns that cannot be fully expressed, the flow rate may be adjusted by combining them. Further, by adjusting the flow rate as described above, it is possible to suppress excessive consumption of the flow rate due to fogging factors, and therefore, the flow rate consumption can be suppressed.

As described above, according to the present embodiment, it is possible to cope with both clouding due to contaminants from the periphery of the projection optical system and clouding due to contaminants from the resist on the substrate, while suppressing the consumption of the supply gas flow rate.

<Second embodiment>
With reference to FIG. 8, an exposure apparatus in a second embodiment will be described. Similar to FIG. 3, FIG. 8 is a diagram of the projection optical system 2 and the first supply section 10 viewed from below. Note that parts not specifically mentioned in the following description are the same as those in the first embodiment. As shown in FIG. 8, in the second embodiment, the first supply section 10 has a plurality of gas supply ports 11, which is one in FIG. 3. As shown in FIG. 8, the first supply section 10 includes a plurality of gas supply ports 11a, 11b, 11c, and a plurality of flow rate adjustment sections 20a, 20b connected to each of the plurality of gas supply ports 11a, 11b, 11c. , 20c. The plurality of flow rate adjustment sections 20a, 20b, and 20c can individually adjust the flow rates of the first gases 40a, 40b, and 40c blown out from the plurality of gas supply ports 11a, 11b, and 11c. The control unit 23 controls each of the plurality of flow rate adjustment units 20a, 20b, and 20c according to cloudy information. Thereby, the flow rate of the first gases 40a, 40b, 40c blown out from each of the plurality of gas supply ports 11a, 11b, 11c of the first supply unit with respect to the flow rate of the second gas 41 from the second supply unit 5 is controlled. can do.

In one example, the control unit 23 can control each of the flow rate adjustment units 20a, 20b, and 20c depending on which of the cloudy patterns shown in FIGS. 9 to 13 the cloudy pattern corresponds to. Below, examples of adjusting the flow rate (flow velocity) of the first gas 40 will be explained for various examples of cloudy patterns shown in FIGS. 9 to 13. Note that, as described with respect to the series of procedures in the first embodiment, the flow rate (flow rate) of the first gas 40 is assumed to be larger than the flow rate (flow rate) of the second gas 41 in the initial state.

9 to 13, the plurality of gas supply ports 11a, 11b, and 11c are arranged along the first direction (X direction) within the surface of the optical element 3. In FIGS. Therefore, each of the plurality of gas supply ports 11a, 11b, and 11c is arranged so as to flow gas in a second direction (-Y direction, ie, airflow direction) orthogonal to the X direction.

A case will be described in which the cloudy pattern, which is the acquired cloudy position information, is the cloudy pattern shown in either FIG. 9(A) or (B). The cloudy pattern in FIG. 9(A) shows that in the second direction within the surface of the optical element 3, the cloudiness is greater on the upstream side of the airflow than in the center, and that the cloudiness exists throughout the first direction. ing. The cloudy pattern in FIG. 9(B) shows a pattern in which the clouding in FIG. 9(A) extends to the downstream side and the entire surface is cloudy. In these cases, it is determined that the main cause of clouding is the second gas 41 passing through the paths 41a, 41b, and 41c shown in FIGS. 1, 2, and 6. Therefore, in these cases, the flow velocity difference between the first gases 40a, 40b, 40c and the second gas 41 is adjusted so that the second gas 41 is difficult to be dragged into or mixed with the first gases 40a, 40b, 40c. It should be small. Therefore, in these cases, the control unit 23 adjusts the flow rate adjusting units 20a, 20b, 20c to reduce the flow rate (flow velocity) of the first gases 40a, 40b, 40c.

Next, a case where the acquired cloudy pattern is shown in any one of FIGS. 10(A), (B), (C), and (D) will be described. In the cloudy patterns shown in FIGS. 10(A) and 10(B), in the second direction within the surface of the optical element 3, the cloudiness is greater on the upstream side of the airflow than in the center, and the cloudiness exists in a part of the first direction. It shows that you are doing it. The cloudy patterns in FIGS. 10(C) and (D) indicate that the clouding in FIGS. 10(A) and (B) extends to the downstream side, respectively. In these cases, it is determined that the main cause of clouding is the second gas 41 passing through the paths 41a and 41b shown in FIGS. 1 and 2. Therefore, in these cases, the difference in flow velocity between the first gas 40a and the second gas 41 should be reduced so that the second gas 41 is less likely to be dragged into or mixed with the first gas 40a. Therefore, in these cases, the control unit 23 adjusts the flow rate adjustment unit 20a to reduce the flow rate (flow velocity) of the first gas 40a corresponding to the position of the cloudy area in the first direction.

Next, a case will be described in which the acquired cloudy pattern is shown in any one of FIGS. 11(A), (B), (C), and (D). The cloudy patterns in FIGS. 11A, 11B, 11C, and 11D show that the end portions of the surface of the optical element 3 are more cloudy than the center portion in the first direction. In this case, it is determined that the main cause of clouding is the second gas 41 passing through the path 41c shown in FIG. Therefore, in this case, the difference in flow velocity between the first gases 40b and 40c and the second gas 41 should be reduced so that the second gas 41 is less likely to be dragged into or mixed with the first gases 40b and 40c. Therefore, in this case, the control unit 23 adjusts the flow rate adjusting units 20b and 20c to reduce the flow rate (flow velocity) of the first gases 40b and 40c blown out from the gas supply ports on the end side in the first direction.

Next, a case will be described in which the acquired cloudy pattern is shown in any one of FIGS. 12(A), (B), (C), (D), (E), and (F). The cloudy patterns in FIGS. 12(A), (B), (C), (D), (E), and (F) are shown in the central part or downstream of the airflow in the second direction within the surface of the optical element 3. It shows that there is a lot of cloudiness on the side. In this case, it is determined that the main cause of fogging is the pollutant 50. Therefore, in this case, the control unit 23 adjusts the flow rate adjustment unit to increase the flow rate (flow velocity) of the gas blown out from the gas supply port corresponding to the position in the first direction of the cloudy area. Specifically, when the cloudy pattern is the pattern shown in FIG. 12(A) or (D), the control unit 23 controls the flow rate adjustment unit to increase the flow rate (flow velocity) of the first gases 40a, 40b, and 40c. Adjust 20a, 20b, and 30c. When the cloudy pattern is the pattern shown in FIG. 12(B) or (E), the control unit 23 adjusts the flow rate adjustment unit 20a to increase the flow rate (flow velocity) of the first gas 40a. When the cloudy pattern is the pattern shown in FIG. 12(C) or (F), the control unit 23 adjusts the flow rate adjusting units 20b, 20c to increase the flow rate (flow velocity) of the first gases 40b, 40c.

Further, when the acquired fogging position information indicates that there is no clouding on the surface of the optical element 3, the control unit 23 uses the flow rate adjustment unit 20 to reduce the flow rate (flow velocity) of the first gas 40. Adjust or maintain that flow rate (flow rate).

As described above, the flow rate adjustment method for a cloudy pattern has been shown, but in the case of a complicated cloudy pattern that cannot be fully expressed, the flow rate may be adjusted by a combination of the cloudy patterns.

In the second embodiment, since there are a plurality of gas supply ports 11, the flow velocity distribution of the first gas 40 in the X direction can be adjusted. Therefore, it is possible to effectively deal with local cloudy distribution while suppressing flow consumption.

<Third embodiment>
Referring to FIG. 13, an exposure apparatus according to a third embodiment will be described. Note that parts not specifically mentioned in the following description are the same as those in the first embodiment and the second embodiment. The difference between FIG. 13 and FIG. 1 is that the exposure apparatus 100 in FIG. 13 is provided with an exhaust section 70 that exhausts gas in the space between the optical element 3 and the substrate W. In FIG. 13, the gas intake port 71 of the exhaust section 70 is directed toward the substrate W, but it may be directed horizontally so as to face the gas supply port 11. The exhaust section 70 is particularly effective against fogging caused by the pollutants 50, and simply by providing the exhaust section 70, the effects of the first and second embodiments can be improved.

Preferably, the size of the gas intake port 71 in the X direction is larger than the irradiation range 61 of the substrate W that is irradiated onto the substrate W via the projection optical system 2 shown in FIG. 3, similarly to the gas supply port 11. More preferably, it is larger than the range 62 through which the laser beam passes through the first surface 31 of the optical element 3 on the substrate W side. Further, preferably, the size of the gas intake port 71 is the same as or larger than the size of the gas supply port 11.

The exhaust flow rate by the exhaust section 70 has an effect if it is larger than 0 (zero), but is preferably equal to or higher than the supply flow rate of the first gas 40 by the first supply section 10. By doing so, the flow of the first gas 40 and the second gas 41 in the space S between the optical element 3 and the substrate W is rectified, and a flow that sucks in the contaminants 50 is not only formed, but also Entrainment and mixing of the first gas 40 and the second gas 41 is reduced.

The number of gas intake ports 71 of the exhaust section 70 may be one, or there may be a plurality of gas supply ports 11 of the first supply section 10 in the second embodiment. When there are a plurality of gas intake ports 71, the configuration may be such that the distribution of the amount of gas taken in by the gas intake ports 71 can be adjusted by controlling the amount of gas taken in each.

According to the configuration including the exhaust section 70 as described above, fogging on the first surface 31 of the optical element 3 is prevented by adjusting the flow rate (flow velocity) of the first gas 40 as described in the first embodiment and the second embodiment. The reduction effect can be obtained more effectively.

<Fourth embodiment>
An exposure apparatus according to a fourth embodiment will be described with reference to FIG. 14. Note that parts not specifically mentioned in the following description are the same as those in the first embodiment, the second embodiment, and the third embodiment. The difference between FIG. 14 and FIG. 13 is that an exhaust adjustment section 81 for adjusting the amount of exhaust by the exhaust section 70 is provided.

Similar to the first to third embodiments, the flow rate of the first gas 40 from the first supply unit 10 is adjusted by the flow rate adjustment unit 20 depending on the cloudy pattern. In the fourth embodiment, the control unit 23 controls the exhaust gas adjustment unit 81 so that the amount of exhaust gas by the exhaust unit 70 is adjusted according to the amount of gas supplied by the first supply unit 10 . As a result, the exhaust flow rate of the exhaust section 70 is increased or decreased by the exhaust adjustment section 81 in accordance with the increase or decrease in the amount of adjustment of the flow rate of the first gas 40. When there are a plurality of gas supply ports 11 and gas intake ports 71, the exhaust flow rate of the gas intake ports 71 may be increased or decreased in accordance with the increase or decrease in the flow rate of the first gas 40 to each gas supply port 11.

Since the flow of the first gas 40 supplied from the first supply section 10 can be supported by the exhaust section 70, an increase or decrease in the flow rate depending on the cloudy pattern can be suppressed. Furthermore, in the fourth embodiment, the flow of the first gas 40 and the second gas 41 in the space S between the optical element 3 and the substrate W is rectified by adjusting the flow rate of the exhaust gas from the exhaust section 70 by the exhaust adjustment section 81. can be converted into Therefore, a higher fog reduction effect can be obtained than in the first to third embodiments.

<Embodiment related to exposure apparatus>
FIG. 15 is a diagram showing the overall configuration of exposure apparatus 100. The exposure apparatus 100 includes an illumination optical system 21, an original stage 22, a projection optical system 2, a substrate stage 4, and a control section 23 that controls them. The illumination optical system 21 illuminates the original M held on the original stage 22 using light from a light source 24, for example, a laser device. The projection optical system 2 projects and transfers the pattern image from the original M onto the substrate W held on the substrate stage 4. The substrate stage 4 and the original stage 22 are scanned and moved by the control section 23 . The air conditioning unit 26 includes piping components for supplying the first gas 40 to the first supply unit 10 through the flow rate adjustment unit 20, and supplies clean air or nitrogen gas to the first supply unit 10, for example. The second gas 41 is supplied from the second supply section 5 to the space where the first supply section 10 is arranged. The source of the second gas 41 may be clean room air, making it difficult to maintain a completely clean state. In addition, the space in which the first supply unit 10 is arranged uses grease, adhesive, resin, rubber, etc. that are likely to generate contaminants in the drive system and structure of the substrate stage 4, or those parts themselves. It has become difficult to maintain a completely clean state.

The first supply unit 10 described in Embodiments 1 to 4 is arranged between the projection optical system 2 and the substrate stage 4 or in the vicinity thereof, and is arranged between the optical element 3 at the lowest end of the projection optical system 2 and the substrate. A first gas 40 is supplied during the stage 4. The control unit 23 adjusts the flow rate of the first gas 40 so that the flow rate (flow velocity) corresponds to the cloudy pattern so as to protect the optical element 3 from the contaminants 50 generated from the substrate W and the contaminated second gas 41. By controlling the portion 20, fogging of the optical element 3 can be reduced.

<Embodiment of article manufacturing method>
The article manufacturing method according to the embodiment of the present invention is suitable for manufacturing articles such as micro devices such as semiconductor devices and elements having fine structures. The article manufacturing method of the present embodiment includes a step of forming a latent image pattern on a photosensitive agent applied to a substrate using the above exposure device (a step of exposing the substrate), and a step of forming a latent image pattern in this step. and developing the substrate. Additionally, such manufacturing methods include other well-known steps (oxidation, deposition, deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The article manufacturing method of this embodiment is advantageous in at least one of article performance, quality, productivity, and production cost compared to conventional methods.

The invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the following claims are hereby appended to disclose the scope of the invention.

2: Projection optical system, 3: Optical element, 4: Substrate stage, 5: Second supply section, 10: First supply section, 11: Gas supply port, 20: Flow rate adjustment section, 23: Control section, 100: Exposure Device

Claims (14)

An exposure device that exposes a substrate,
a holding part that holds the substrate;
a projection optical system that projects an image of the pattern of the original onto the substrate held by the holding section;
a supply unit that supplies gas to a space between the projection optical system and the substrate held by the holding unit;
a control unit that controls gas supply by the supply unit based on information on cloudiness of an optical element in the projection optical system that faces the substrate held by the holding unit;
An exposure apparatus characterized by having: The supply unit includes:
a gas supply port that blows out the gas supplied to the space;
a flow rate adjustment unit that adjusts the flow rate of gas blown out from the gas supply port;
has
The control unit controls the flow rate adjustment unit based on the information,
The exposure apparatus according to claim 1, characterized in that: The information includes position information of cloudiness on the surface of the optical element,
The control unit includes:
determining the cause of clouding of the optical element based on the position information;
If it is determined that the cause of the clouding is a contaminant generated from the resist on the substrate, controlling the flow rate adjustment unit so that the flow rate of gas supplied to the space is increased;
If it is determined that the cause of the clouding is a contaminant mixed in the gas from outside the space, controlling the flow rate adjustment unit so that the flow rate of the gas supplied to the space is reduced.
The exposure apparatus according to claim 2, characterized in that: The supply unit includes:
a plurality of gas supply ports that blow out gas supplied to the space;
a plurality of flow rate adjustment units that individually adjust the flow rate of gas blown out from the plurality of gas supply ports;
has
The plurality of gas supply ports are arranged along a first direction within the surface of the optical element, and are each arranged to flow gas in a second direction perpendicular to the first direction,
The control unit controls each of the plurality of flow rate adjustment units based on the information,
The exposure apparatus according to claim 1, characterized in that: The information includes position information of cloudiness on the surface of the optical element,
If the positional information indicates that the end portions of the surface of the optical element are more cloudy than the central portion in the first direction, the control unit controls the first one of the plurality of gas supply ports. 5. The exposure apparatus according to claim 4, wherein the plurality of flow rate adjusting units are controlled to reduce the flow rate of the gas blown out from the gas supply port on the end side in the direction. The information includes position information of cloudiness on the surface of the optical element,
When the positional information indicates that cloudiness is greater on the upstream side of the airflow than in the center in the second direction within the surface of the optical element, the control unit may cause the control unit to 5. The exposure apparatus according to claim 4, wherein the plurality of flow rate adjusting units are controlled to reduce a flow rate of gas blown out from a gas supply port corresponding to a cloudy position in the first direction. The information includes position information of cloudiness on the surface of the optical element,
When the positional information indicates that cloudiness is large in the central part of the surface of the optical element in the second direction or on the downstream side of the gas, the control unit controls one of the plurality of gas supply ports. 5. The exposure apparatus according to claim 4, wherein the plurality of flow rate adjusting units are controlled to increase the flow rate of gas blown out from the gas supply port corresponding to the position of the cloudy area in the first direction. The information includes position information of cloudiness on the surface of the optical element,
When the position information indicates that there is no clouding on the surface of the optical element, the control unit controls the plurality of gas supply ports to reduce or maintain the flow rate of the gas blown out from each of the plurality of gas supply ports. 5. The exposure apparatus according to claim 4, wherein the exposure apparatus controls a flow rate adjusting section. The exposure apparatus according to any one of claims 5 to 8, wherein the control unit acquires the position information based on a cloudy determination value profile on the surface of the optical element. The exposure apparatus according to any one of claims 1 to 9, further comprising an exhaust section that exhausts gas from the space. 11. The exposure apparatus according to claim 10, further comprising an exhaust adjustment section that adjusts an exhaust amount by the exhaust section. 12. The exposure apparatus according to claim 11, wherein the control section controls the exhaust adjustment section so that the exhaust amount by the exhaust section is adjusted according to the amount of gas supplied by the supply section. A method for adjusting an exposure device that exposes a substrate, the method comprising:
identifying a cloudy pattern representing a cloudy position of an optical element of a projection optical system arranged to face the substrate;
adjusting the flow rate or flow rate of gas supplied to the space between the substrate and the optical element according to the identified cloudy pattern;
An adjustment method characterized by having the following. exposing the substrate using an exposure apparatus adjusted according to the adjustment method according to claim 13;
Developing the exposed substrate;
A method for manufacturing an article, comprising: manufacturing an article from the developed substrate.

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