TW201640141A - Radiation sensor - Google Patents

Abstract

A radiation sensor comprising a chamber for containing a gas, the chamber having a first opening and a second opening such that a radiation beam can enter the chamber through the first opening, propagate through the chamber and exit the chamber through the second opening, a gas supply mechanism configured to supply hydrogen or helium into the chamber, a first electrode situated in the chamber, a second electrode situated in the chamber, a voltage source configured to maintain a potential difference between the first electrode and the second electrode, an electrical sensor configured to measure an electrical current flowing through at least one of the first electrode and the second electrode, the electrical current resulting from ionization of the hydrogen or helium in the chamber caused by a radiation beam propagating through the chamber and a processor operable to determine, from the measured electrical current, at least one of a power and a position of a radiation beam propagating through the chamber.

Description

Radiation sensor

The present invention relates to a radiation sensor for determining the position and/or power of a radiation beam. In detail, but not exclusively, the radiation beam can propagate in the lithography system.

A lithography apparatus is a machine that is constructed to apply a desired pattern onto a substrate. The lithography apparatus can be used, for example, in the manufacture of integrated circuits (ICs). The lithography apparatus can, for example, project a pattern from a patterned device (eg, a reticle) onto a layer of radiation-sensitive material (resist) provided on the substrate.

The wavelength of the radiation used by the lithography apparatus to project the pattern onto the substrate determines the minimum size of features that can be formed on the substrate. Compared to conventional lithography devices which can, for example, use electromagnetic radiation having a wavelength of 193 nm, use extreme ultraviolet (EUV) radiation of electromagnetic radiation having a wavelength in the range of 4 nm to 20 nm. The lithography apparatus can be used to form smaller features on the substrate.

For lithography and other applications, one or more properties of the radiation beam may need to be measured.

One of the objects of the present invention is to prevent or mitigate at least one of the problems of the prior art.

According to a first aspect of the present invention, a radiation sensor includes: a chamber for containing a gas, the chamber having a first opening and a second opening, such that a radiation beam is Entering the chamber through the first opening, propagating through the chamber and exiting the chamber through the second opening; a gas supply mechanism configured to supply hydrogen or helium gas Should be in the chamber; a first electrode located in the chamber; a second electrode located in the chamber; a voltage source configured to be at the first electrode and the second electrode Maintaining a potential difference therebetween; an inductive detector configured to measure a current flowing through at least one of the first electrode and the second electrode, the current resulting from propagation through one of the chambers An ionization of the hydrogen or helium gas in the chamber caused by the radiation beam; and a processor operable to determine from the measured current to propagate power through one of the radiation beams of the chamber and a position At least one of them.

Propagating a beam of radiation through one of the chambers causes ionization of the gas in the chamber, thereby causing ions and electrons to be generated in one of the interaction regions through which the radiation beam propagates. The potential difference maintained between the electrodes in the chamber causes the plasma to be attracted to one of the electrodes and cause the plasma to be attracted to the other of the electrodes, thereby inducing a current flow Pass the electrodes. This generation of ions in the interaction zone through which the radiation beam propagates and subsequent transport of the plasma to an electrode can result in a reduction in the amount of gas present in the interaction zone. Both hydrogen and helium have a relatively low ionization cross section. In particular, hydrogen and helium have a relatively low ionization cross section at the wavelengths at which the radiation sensor may be required to measure the radiation. For example, hydrogen and helium have a relatively low ionization cross section at EUV wavelengths.

Using a gas having a relatively low ionization cross section reduces the number of ionization events resulting from a radiation beam having a given power, and thus advantageously reduces the gas removed from the interaction zone due to ionization The amount. Reducing the amount of gas removed from the interaction zone increases the amount of gas present in the interaction zone for subsequent ionization and reduces any wear of the gas in the interaction zone. The lack of reduced gas in the interaction zone advantageously allows continuous measurement of the radiation beam without significantly reducing the accuracy of making the measurement.

The use of hydrogen or helium having a relatively low ionization cross section may be particularly advantageous for the measurement of a pulsed radiation beam having a relatively high repetition rate.

The gas supply mechanism can be configured to maintain a desired hydrogen or helium pressure in the chamber.

The gas supply mechanism can be configured to maintain a hydrogen or helium pressure of greater than about 0.01 Pascals in the chamber.

The gas supply mechanism can be configured to maintain a hydrogen or helium pressure of less than about 100 Pascals in the chamber.

According to a second aspect of the present invention, a radiation sensor includes: a chamber for containing a gas, the chamber having a first opening and a second opening, such that a radiation beam is Entering the chamber through the first opening, propagating through the chamber and exiting the chamber through the second opening; a gas supply mechanism configured to maintain a gas in the chamber at greater than about 0.01 Pascal a pressure; a first electrode located in the chamber; a second electrode located in the chamber; a voltage source configured to maintain between the first electrode and the second electrode a potential difference; an inductive detector configured to measure a current flowing through at least one of the first electrode and the second electrode, the current being caused by a radiation beam propagating through one of the chambers Ionization of the gas in the chamber; and a processor operative to determine at least one of a power and a position of one of the radiation beams propagating through the chamber from the measured current.

Maintaining a pressure greater than about 0.01 Pascals within the chamber advantageously increases the current flowing through the electrodes due to the propagation of a radiation beam having a given power through the chamber. The increase in current flowing through the electrodes increases the signal upon which the determination of the power and/or the position of the radiation beam is based, thereby advantageously increasing the signal-to-noise ratio by which the determination is made. Increasing the signal-to-noise ratio by which the power of the radiation beam and/or the determination of the position is made may allow even when the radiation beam causes a portion of the amount of gas present in the interaction region through which the radiation beam propagates through This decision was also made.

The gas supply mechanism can be configured to maintain a gas in the chamber at a pressure greater than about 0.1 Pascal.

The gas supply mechanism can be configured to maintain a gas in the chamber at a pressure of less than about 100 Pascals.

The gas supply mechanism can be configured to maintain hydrogen or helium in the chamber.

The radiation sensor can further include a third electrode located in the chamber, wherein the voltage source is configured to maintain a potential difference between the first electrode and the third electrode, and wherein the inductive detector passes Configuring to measure a current flowing through one of the second electrodes and to measure a current flowing through one of the third electrodes, wherein the first, second, and third electrodes are configured to propagate through one of the chambers A change in position of the radiation beam in a first direction causes a change in one of the current flowing through the second electrode and a change in flow through the third electrode.

Providing the third electrode in the chamber and configuring the electrodes such that a change in position of a radiation beam in the chamber causes a change in one of the currents flowing through the electrodes to advantageously allow the radiation beam This position makes an accurate decision.

The processor is operative to compare the current flowing through the second electrode with the current flowing through the third electrode, and from the comparison determines a position of the radiation beam propagating through one of the chambers in the first direction .

The voltage source can be configured to maintain the first electrode at a higher voltage than the second electrode and at a higher voltage than the third electrode.

The voltage source can be configured to maintain a potential difference between the first electrode and the second electrode and maintain a potential difference between the first electrode and the third electrode that is substantially identical to each other.

The radiation sensor can further include a fourth electrode located in the chamber, wherein the voltage source is configured to maintain a potential difference between the fourth electrode and the second electrode and configured to Maintaining a potential difference between the fourth electrode and the third electrode, wherein the first and fourth electrodes are configured such that a position of the radiation beam propagating through one of the chambers in a first direction changes to cause flow through the first One of the currents of an electrode changes and flows through One of the currents between the fourth electrodes changes.

The inductive detector can be configured to measure a current flowing through one of the first electrodes and a current flowing through the fourth electrode.

The processor is operative to compare the current flowing through the first electrode with the current flowing through the fourth electrode, and from the comparison determines a position of the radiation beam propagating through one of the chambers in the first direction .

The radiation sensor can further include a fifth electrode in the chamber, a sixth electrode in the chamber, and a seventh electrode in the chamber, wherein the voltage source is configured to Maintaining a potential difference between the fifth electrode and the sixth electrode and maintaining a potential difference between the fifth electrode and the seventh electrode, and wherein the inductor is configured to measure flow through the sixth electrode And measuring a current flowing through one of the seventh electrodes, and wherein the fifth electrode, the sixth electrode, and the seventh electrode are configured such that a light beam propagating through one of the chambers is in a second direction A change in position causes a change in one of the current flowing through the sixth electrode and one of the currents flowing through the seventh electrode.

The processor is operative to compare the current flowing through the sixth electrode with the current flowing through the seventh electrode, and from the comparison determines a position of the radiation beam propagating through one of the chambers in the second direction .

The first and second directions may extend perpendicular to the direction of propagation of the radiation beam through the chamber.

The first and second directions may extend perpendicular to each other.

The radiation sensor can further include an eighth electrode located in the chamber, wherein the voltage source is configured to maintain a potential difference between the eighth electrode and the sixth electrode and configured to Maintaining a potential difference between the eight electrodes and the seventh electrode, wherein the fifth and eighth electrodes are configured such that a position of the radiation beam propagating through one of the chambers in the second direction changes to cause flow through the first One of the five electrodes changes and the flow changes through one of the currents between the eighth electrodes.

The inductive detector can be configured to measure current flowing through one of the fifth electrodes and flowing through one of the eighth electrodes.

The processor is operative to compare the current flowing through the fifth electrode with the current flowing through the eighth electrode, and from the comparison determines a position of the radiation beam propagating through one of the chambers in the second direction .

The radiation sensor can further include a beam splitter configured to receive a radiation beam and split the radiation beam into a first portion and a second portion and to direct the second portion to propagate through the chamber.

The beam splitter can comprise a grating.

According to a third aspect of the present invention, a radiation sensor includes: a chamber for containing a gas, the chamber having a first opening and a second opening, such that a radiation beam is Passing through the first opening into the chamber, propagating through the chamber and exiting the chamber through the second opening; a gas supply mechanism configured to supply a gas into the chamber; a first electrode Is located in the chamber; a second electrode located in the chamber; a third electrode located in the chamber; a voltage source configured to be at the first electrode and the second Maintaining a potential difference between the electrodes and maintaining a potential difference between the first electrode and the third electrode; and an inductance detector configured to measure current flowing through one of the second electrodes and flowing the third a current of one of the electrodes resulting from ionization of the gas in the chamber caused by a radiation beam propagating through one of the chambers, wherein the first, second, and third electrodes are configured to cause propagation Radiating the beam through one of the chambers in a first direction One of the positional changes causes one of the current flowing through the second electrode to change and one of the currents flowing through the third electrode to change, the radiation sensor further comprising a processor operable to flow through the The measured current of the second electrode and the measured current flowing through the third electrode determine a position of the radiation beam propagating through one of the chambers in the first direction.

The chamber can be configured to extend generally between the first opening and the second opening Extending a beam axis to receive a radiation beam, and wherein the second and third electrodes are configured such that one of the beam axis to one of the second and third electrodes projects for the first portion of the projection The three electrodes are coincident and coincide with the second electrode for a second portion of the projection, and wherein the electrodes are configured such that a position of the beam axis in the first direction changes to cause the first portion of the projection A change in length relative to the length of the second portion of the projection.

The second electrode can include a first straight edge configured to intersect the beam axis to the projection on the second electrode, and the third electrode can include the beam axis configured to the third electrode The second straight edge of the projection intersects.

The first straight edge and the second straight edge may be parallel to each other.

The processor is operative to compare the current flowing through the second electrode with the current flowing through the third electrode to determine from the comparison that the radiation beam propagates through the chamber at the location in the first direction .

The voltage source can be configured to maintain the first electrode at a higher voltage than the second electrode and at a higher voltage than the third electrode.

The processor is further operable to determine that the radiation beam propagates through one of the chambers from at least one of the measured current flowing through the second electrode and the measured current flowing through the third electrode One power.

The radiation sensor can further include a fifth electrode in the chamber, a sixth electrode in the chamber, and a seventh electrode in the chamber, wherein the voltage source is configured to Maintaining a potential difference between the fifth electrode and the sixth electrode and maintaining a potential difference between the fifth electrode and the seventh electrode, wherein the inductor is configured to measure flow through one of the sixth electrodes And flowing a current through the seventh electrode, wherein the fifth electrode, the sixth electrode, and the seventh electrode are configured such that a position of the radiation beam propagating through one of the chambers changes in a second direction Having caused one of the currents flowing through the sixth electrode to change and one of the currents flowing through the seventh electrode to change, and wherein the The processor is operable to determine from the measured current flowing through the sixth electrode and the measured current flowing through the seventh electrode to propagate a position of the radiation beam passing through one of the chambers in the second direction .

The sixth and seventh electrodes can be configured such that one of the beam axis to one of the sixth and seventh electrodes projects for the first portion of the projection and coincides with the sixth electrode and for the projection Two portions are coincident with the seventh electrode, and wherein the sixth and seventh electrodes are configured such that a position of the beam axis in the second direction changes to cause a length of the first portion of the projection relative to the projection A change in the length of the second portion.

The processor is operative to compare the current flowing through the sixth electrode with the current flowing through the seventh electrode to determine from the comparison that a radiation beam propagates through the chamber in a position in the second direction .

The first and second directions may extend perpendicular to the direction of propagation of the radiation beam through the chamber.

The first and second directions may extend perpendicular to each other.

According to a fourth aspect of the present invention there is provided a radiation sensor system comprising: a first radiation sensor according to any one of the first, second or third aspects, configured to Determining at least one of a position of a radiation beam at a first location and a power; a second radiation sensor according to any one of the first, second or third aspects, Configuring to determine at least one of a location of the radiation beam at a second location and a power.

The first radiation sensor can be configured to determine a position of the radiation beam at the first location, and the second radiation sensor can be configured to determine that the radiation beam is at the second location a location. The radiation sensor system can further include a processor configured to compare the determined position of the radiation beam at the first location with the determined position of the radiation beam at the second location, and From the comparison, a direction of propagation of the radiation beam between the first radiation sensor and the second radiation sensor is determined.

The first radiation sensor can be configured to determine a position of the radiation beam at the first location, and the second radiation sensor can be configured to determine that the radiation beam is at the second location One power.

The radiation sensor system can further include a beam splitter configured to receive the radiation beam between the first portion and the second portion, split the radiation beam into a first portion and a second portion and The second portion is directed to the second portion.

According to a fifth aspect of the present invention, a lithography system is provided, comprising: a radiation source configured to provide a primary radiation beam; a plurality of lithography devices; a beam delivery system configured to Splitting the primary radiation beam into at least one branch radiation beam and directing the at least one branch radiation beam to at least one lithography device; and radiating according to any one of the first, second or third aspects a sensor or a radiation sensor system according to the fourth aspect, the radiation sensor or radiation sensor system configured to determine a power and a position of the primary radiation beam and/or a branch radiation beam At least one of them.

The radiation source can be configured to provide an EUV primary radiation beam.

The radiation source can be configured to provide a pulsed primary radiation beam having a repetition rate greater than about 100 Hz

The radiation source can comprise at least one free electron laser.

According to a sixth aspect of the present invention, there is provided a method of measuring at least one of a position of a radiation beam and a power, the method comprising: providing a chamber for containing a gas, the chamber having a first opening and a second opening, such that a radiation beam can enter the chamber through the first opening, propagate through the chamber and exit the chamber through the second opening; supply hydrogen or helium gas to the chamber Maintaining a potential difference between a first electrode located in the chamber and a second electrode located in the chamber; directing a radiation beam to propagate through the chamber; measuring flow through the electrodes a current between at least one of the currents resulting from ionization of hydrogen or helium in the chamber caused by the radiation beam propagating through the chamber; and passing the measured current through the determined current One of the chambers radiates light At least one of a bundle power and a position.

The method can further comprise maintaining the hydrogen or helium in the chamber at a desired pressure.

The hydrogen or helium gas can be maintained at a pressure greater than about 0.01 Pascal.

The hydrogen or helium gas can be maintained at a pressure of less than about 100 Pascals.

A method of measuring at least one of a position of a radiation beam and a power, the method comprising: providing a chamber for containing a gas, the chamber having a first opening and a second opening such that a radiation beam can enter the chamber through the first opening, propagate through the chamber and exit the chamber through the second opening; supply a gas into the chamber and maintain the gas at greater than about 0.01 Pascals a pressure; maintaining a potential difference between a first electrode located in the chamber and a second electrode located in the chamber; directing a radiation beam to propagate through the chamber; measuring flow through the electrodes a current of at least one of the currents resulting from ionization of the gas in the chamber caused by the radiation beam propagating through the chamber; and determining from the measured current to propagate through the chamber At least one of a power and a position of the radiation beam.

The gas can be maintained at a pressure greater than about 100 Pascals.

The various aspects and features of the present invention, as set forth in the <RTIgt;

8‧‧‧ openings

10‧‧‧琢面面镜镜装置

11‧‧‧ Faceted Optic Mirror Device

13‧‧‧Mirror

14‧‧‧Mirror

21‧‧‧Injector

22‧‧‧ Linear Accelerator

23‧‧‧ bunching compressor

24‧‧‧ undulator

26‧‧‧Electronic reducer

100‧‧‧beam cut-off

101‧‧‧radiation sensor

102‧‧‧radiation beam

102a‧‧‧first projection

102b‧‧‧second projection

102c‧‧‧ third projection

105‧‧‧beam catheter

107a‧‧‧first aperture plate

107b‧‧‧Second aperture plate

108a‧‧‧first opening

108b‧‧‧second opening

110‧‧‧ chamber

112‧‧‧ gas supply parts

114‧‧‧ valve

116‧‧‧ pump

118‧‧‧pressure sensor

121‧‧‧First electrode

122‧‧‧second electrode

122a‧‧‧The first straight edge

123‧‧‧ third electrode

123a‧‧‧Second straight edge

124‧‧‧fourth electrode

125‧‧‧Electronics

125'‧‧‧Electronics

131‧‧‧First electrical connector

132‧‧‧Second electrical connector

133‧‧‧ Third electrical connector

134‧‧‧4th electrical connector

135‧‧‧Part 1

135a‧‧‧Part 1

135b‧‧‧Part 1

135c‧‧‧Part 1

137‧‧‧Part II

137a‧‧‧Part II

137b‧‧‧Part II

137c‧‧‧Part II

141‧‧‧voltage source

143a‧‧‧first voltmeter

143b‧‧‧second voltmeter

145a‧‧‧First resistor

145b‧‧‧second resistor

147‧‧‧Inductance detector

151‧‧‧ processor

153‧‧‧Interaction zone

202‧‧‧radiation beam

203‧‧‧Part 1

204‧‧‧Part II

205‧‧‧beam splitter

301‧‧‧radiation sensor system

302‧‧‧radiation beam

303‧‧‧Part 1

304‧‧‧Part II

305‧‧‧ Beam splitter

441a‧‧‧First voltage supply

441b‧‧‧Second voltage supply

443a‧‧‧First Voltmeter

443b‧‧‧second voltmeter

443c‧‧‧ third voltmeter

443d‧‧‧fourth voltmeter

445a‧‧‧First resistor

445b‧‧‧second resistor

445c‧‧‧third resistor

445d‧‧‧fourth resistor

447a‧‧‧First Current Sensor

447b‧‧‧Second current sensor

447c‧‧‧ third current sensor

447d‧‧‧fourth current sensor

‧‧‧‧ angle

B‧‧‧Main radiation beam

B _a ‧‧‧ branch radiation beam

B _a '‧‧‧ patterned radiation beam

B _b ‧‧‧ branch radiation beam

B _n ‧‧‧ branch radiation beam

BDS‧‧‧ Beam Delivery System

B _FEL ‧‧‧radiation beam/laser beam

E‧‧‧Electronic beam

FEL‧‧‧ free electron laser

I ₁ ‧‧‧First current

I ₂ ‧‧‧second current

I ₃ ‧‧‧third current

I ₄ ‧‧‧fourth current

IL‧‧‧Lighting System

L ‧‧‧ length

LA _a ‧‧‧ lithography device

LA _b ‧‧‧ lithography device

LA _n ‧‧‧ lithography device

LS‧‧‧ lithography system

MA‧‧‧patterned device

MT‧‧‧Support structure

PS‧‧‧Projection System

RS‧‧‧radiation sensor

RS ₁ ‧‧‧First Radiation Sensor

RS ₂ ‧‧‧Second Radiation Sensor

SO‧‧‧radiation source

W‧‧‧Substrate

WT‧‧‧ substrate table

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIG. 1 is a schematic diagram of a lithography system including a free electron laser in accordance with an embodiment of the present invention. 2 is a schematic illustration of a lithography apparatus forming part of the lithography system of FIG. 1; - FIG. 3 is a schematic illustration of a free electron laser forming part of the lithography system of FIG. 1; - Figure 4 is a schematic illustration of a radiation sensor in accordance with an embodiment of the present invention; - Figure 5 is a schematic illustration of an electrode forming part of the radiation sensor of Figure 4; - Figure 6 is a diagram of Figure 4 Schematic illustration of the electrodes and electronics of a portion of the radiation sensor; - Figure 7 is a schematic illustration of the projection of the radiation beam from three different locations onto the electrode of Figure 5; - Figure 8 is a radiation sensor A schematic illustration of an electrode of a portion of an alternate embodiment; - Figure 9 is a schematic illustration of an alternate embodiment of an electronic component that can form part of a radiation sensor; - Figure 10 is a steady state gas inside the radiation sensor A schematic representation of the pressure as a function of the repetition rate of the radiation beam propagating through the gas sensor; - Figure 11 is a schematic illustration of a radiation sensor and beam splitter configured to determine at least one property of the radiation beam; - Figure 12 is a schematic illustration of a radiation sensor system in accordance with an embodiment of the present invention.

Figure 1 shows a lithography system LS in accordance with one embodiment of the present invention. LS lithography system comprises a radiation source SO, the RS radiation sensor, the beam delivery system and a plurality of BDS LA _a lithography apparatus to LA _n (e.g., eight lithography apparatus). The radiation source SO is configured to generate an extreme ultraviolet (EUV) radiation beam B (which may be referred to as a main beam).

The beam delivery system BDS comprises beam splitting optics and may optionally include beam expanding optics and/or beam shaping optics. The main radiation beam B is split into a plurality of radiation beams B _a to B _n (which may be referred to as branch beams), and each of the plurality of radiation beams B _a to B _n is directed to the lithography by the beam delivery system BDS One of the devices LA _a to LA _n is different. The radiation sensor RS shown in FIG. 1 is configured to measure one or more properties (eg, power and/or position) of the primary beam B. Additionally or alternatively, the radiation sensor RS can be configured to measure one or more properties of the branched radiation beams B _a through B _n .

The selected beam expanding optics (not shown) are configured to increase the cross-sectional area of the radiation beam B. Advantageously, this reduces the thermal load on the mirror surface downstream of the beam expanding optics. This allows the mirror surface downstream of the beam expanding optics to be of a lower gauge, less cooled, and therefore less expensive. Additionally or alternatively, it may allow the downstream mirror to be closer to normal incidence. For example, the beam expanding optics are operable to extend the main beam B from a diameter of about 100 microns to a diameter greater than 10 centimeters before the main beam B is split by the beam splitting optics.

In one embodiment, the branched radiation beams B _a through B _n are each directed through a respective attenuator (not shown). Each attenuator can be configured to adjust the intensity of the branch radiation beams B _a through B _n before a respective branch radiation beam B _a to B _{n is} delivered into its corresponding lithography device LA _a to LA _n .

The radiation source SO, a beam delivery system and the BDS to LA _a lithography apparatus LA _n may all be constructed and arranged such that it can be isolated from the outside environment. Vacuum may be provided a radiation source SO, a beam delivery system and the BDS to LA _a lithography apparatus LA _n is at least partially in order to reduce the absorption of EUV radiation. Different portions of the lithography system LS can have vacuums at different pressures (i.e., different pressures maintained below atmospheric pressure).

Referring to Figure 2, LA _a lithography apparatus comprising an illumination system IL, was configured to support a patterning device MA (e.g., mask) the support structure MT, projection system PS, and configured to support the substrate W by the substrate table WT . The illumination system IL configured to regulate via the branch lithographic apparatus LA _a reception of the radiation beam B _a, B _a radiation beam after the branch incident on the patterning device MA. The projection system PS is configured to project a radiation beam B _a ' (now patterned by the patterned device MA) onto the substrate W. The substrate W may include a previously formed pattern. In this case, the lithography device aligns the patterned radiation beam B _a ' with the pattern previously formed on the substrate W.

The received by the lithography apparatus LA _a branch B _a radiation beam from a beam delivery system to the illumination system IL BDS transmitted through the illumination system IL of the structure enclosed in the opening 8. Optionally, the branching radiation beam B _a can be focused to form an intermediate focus at or near the opening 8 .

The illumination system IL can include a faceted field mirror device 10 and a faceted pupil mirror device 11. The faceted field mirror device 10 and the pupilized pupil mirror device 11 together provide the desired cross-sectional shape and desired angular distribution to the radiation beam B _a . The radiation beam B _{a is} transmitted from the illumination system IL and is incident on the patterned device MA held by the support structure MT. And reflective patterning device MA patterned beam of radiation to form a patterned light beam B _a '. In addition to or in lieu of the faceted field mirror device 10 and the reduced pupil mirror device 11, the illumination system IL may also include other mirrors or devices. The illumination system IL can, for example, comprise an array of independently movable mirrors. The independently movable mirror can, for example, have a width of less than 1 mm. The independently movable mirror can be, for example, a microelectromechanical system (MEMS) device.

After the self-patterning device MA is redirected (eg, reflected), the patterned radiation beam B _a ' enters the projection system PS. The projection system PS comprises a plurality of mirrors 13, 14 configured to project a radiation beam B _a ' onto _a substrate W held by a substrate table WT. The projection system PS can apply a reduction factor to the radiation beam to form an image having features that are less than the corresponding features on the patterned device MA. For example, a reduction factor of 4 can be applied. Although the projection system PS has two mirrors in Figure 2, the projection system can include any number of mirrors (e.g., six mirrors).

LA _a lithography apparatus is operable to impart a pattern to the radiation beam B _a cross section of the radiation beam B _a, and the projection of the patterned radiation beam onto a target portion of the substrate, whereby the target portion of the substrate by an exposure to Patterned radiation. The lithography apparatus LA _a can be used, for example, in a scanning mode in which the support structure MT and the substrate stage WT are synchronously scanned while projecting _a pattern imparted to the radiation beam B _a ' onto the substrate W (ie, dynamic exposure). The speed and direction of the substrate table WT relative to the support structure MT can be determined by the reduction ratio and the image inversion characteristic of the projection system PS.

Referring again to FIG. 1, the radiation source SO configured to generate with sufficient power to the EUV lithography apparatus LA _a LA _n are each to be supplied to the radiation beam B. As mentioned above, the radiation source SO may comprise a free electron laser.

3 is a schematic depiction of a free electron laser FEL including an injector 21, a linear accelerator 22, a bunching compressor 23, an undulator 24, an electronic retarder 26, and a beam stop 100.

The injector 21 is configured to produce a beamed electron beam E and includes an electron source (eg, a hot electron cathode or photocathode) and an accelerating electric field. The electrons in the electron beam E are further accelerated by the linear accelerator 22. In one example, linear accelerator 22 can include: a plurality of radio frequency cavities axially spaced along a common axis; and one or more radio frequency power sources operable to pass electron convergence between electromagnetic fields The electromagnetic field is controlled along the common axis to accelerate each electron bunching. The cavity can be a superconducting radio frequency cavity. Advantageously, this allows: a relatively large electromagnetic field is applied in a high-effect interval cycle; a larger beam aperture, which causes less loss due to the wake field; and an increase in transmission to the beam (relative to dissipation through the cavity wall) The fraction of the radio frequency. Alternatively, the cavity is conventionally electrically conductive (ie, not superconducting) and may be formed of, for example, copper. Other types of linear accelerators can be used, such as a laser wake field accelerator or a counter free electron laser accelerator.

The electron beam E is passed through a bunching compressor 23 disposed between the linear accelerator 22 and the undulator 24, as appropriate. The bunching compressor 23 is configured to spatially compress the existing electron bunching in the electron beam E. One type of buncher compressor 23 includes a radiation field that is oriented transverse to electron beam E. The electrons in the electron beam E interact with the radiation and are clustered with other electrons in the vicinity. Another type of buncher compressor 23 includes a magnetic orbital curve in which the length of the path followed by the electron as it passes through the orbital curve depends on its energy. This type of buncher compressor can be used to compress electron bunching that has been accelerated in the linear accelerator 22 by a plurality of resonant cavities.

The electron beam E is then passed through the undulator 24. Generally, the undulator 24 includes a plurality of modules (not shown). Each module includes a periodic magnet structure, the periodic magnet The structure is operable to generate a periodic magnetic field and is configured to direct the relativistic electron beam E produced by the injector 21 and the linear accelerator 22 along a periodic path within the module. The periodic magnetic field generated by each undulator module causes the electrons to follow an oscillating path around the central axis. Thus, within each undulator module, electrons radiate electromagnetic radiation generally in the direction of the central axis of the undulator module.

The path followed by the electrons can be sinusoidal and planar, with electrons periodically traversing the central axis. Alternatively, the path can be helical, with the electrons rotating about the central axis. The type of oscillating path can affect the polarization of the radiation emitted by the free electron laser. For example, a free electron laser that causes electrons to propagate along a helical path can emit elliptical polarized radiation, which may be desirable for exposing substrate W by some lithography apparatus.

As electrons move through each undulator module, the electrons interact with the electric field of the radiation to exchange energy with the radiation. In general, the amount of energy exchanged between electrons and radiation will oscillate rapidly, unless the conditions are close to the resonant condition. Under resonant conditions, the interaction between electrons and radiation causes the electrons to bunch together into a micro-bundle that is modulated at the wavelength of the radiation within the undulator, and the stimulating radiation is emitted coherently along the central axis. The resonance condition can be given by:

Where λ _em is the wavelength of the radiation, λ _u is the undulator period for the undulator module through which the electrons are propagating, γ is the Lorentz factor of the electron, and K is the undulator parameter. A depends on the geometry of the undulator 24: for a spiral undulator that produces circularly polarized radiation, A = 1; for a planar undulator, A = 2; and for producing elliptical polarized radiation (ie, neither round Spiral undulator with shape polarization and nonlinear polarization), 1 < A < 2. In practice, each electron bunching will have an energy spread, but this spread can be minimized as much as possible (by generating an electron beam E with a low emissivity). The undulator parameter K is typically about 1 and is given by:

Where q and m are the charge and mass of the electron, B ₀ is the amplitude of the periodic magnetic field, and c is the speed of light.

The resonant wavelength λ _em is equal to the first harmonic wavelength radiated spontaneously by the electrons moving through each undulator module. The free electron laser FEL can operate in a self-amplifying spontaneous emission (SASE) mode. The operation in the SASE mode requires a low energy spread of electron bunching in the electron beam E before the electron beam E enters each undulator module. Alternatively, the free electron laser FEL can include a seed radiation source that can be amplified by stimulated emission within the undulator 24. The free electron laser FEL is operable as a Recirculating Amplifier Free Electron Laser (RAFEL) in which a portion of the radiation produced by the free electron laser FEL is used to inoculate the further generation of the radiation.

Moving the electrons through the undulator 24 causes the amplitude of the radiation to increase, i.e., the free electron laser FEL can have a non-zero gain. The maximum gain can be achieved when the resonance condition is met or when the condition is close to but slightly off resonance.

The electrons that meet the resonance condition as they enter the undulator 24 will lose (or gain) energy as they emit (or absorb) the radiation, such that the resonance condition is no longer satisfied. Thus, in some embodiments, the undulator 24 can be wedge shaped. That is, the amplitude of the periodic magnetic field and/or the undulator period λ _u may vary along the length of the undulator 24 to bunch the electrons as they are directed through the undulator 24 Stay at or near resonance. The wedge shape can be achieved by varying the amplitude of the periodic magnetic field and/or the undulator period λ _u within each undulator module and/or between different modules. Additionally or alternatively, the wedge shape can be achieved by varying the helicity of the undulator 24 (by varying the parameter A) within each undulator module and/or between different modules.

The radiation generated in the undulator 24 is output as a radiation beam B _FEL .

After leaving the undulator 24, the electron beam E is absorbed by the cutoff 100. Cutoff 100 may contain a sufficient amount of material to absorb the electron beam E. The material can have a threshold energy for inducing radioactivity. Electrons entering the cutoff 100 with energy below the threshold energy may only produce gamma ray showers, but will not induce any significant level of radioactivity. The material can have a high threshold energy for inducing radioactivity by electron impact. For example, the beam cutoff may comprise aluminum (Al) having a threshold energy of approximately 17 MeV. It may be desirable to reduce the energy of the electrons in the electron beam E before entering the cutoff 100. This removes or at least reduces the need to remove and throw away radioactive waste from the cutoff 100. This is advantageous because the removal of radioactive waste would require the free electron laser FEL to be periodically shut down and the throwing of radioactive waste can be expensive and can have serious environmental impacts.

The energy of the electrons can be reduced before the electrons in the electron beam E enter the cutoff device 100 by directing the electron beam E through a speed reducer 26 disposed between the undulator 24 and the beam stop 100.

In one embodiment, the electron beam E exiting the undulator 24 can be decelerated by passing electrons back through the linear accelerator 22 at a phase difference of 180 degrees with respect to the electron beam generated by the injector 21. Therefore, the RF field in the linear accelerator is used to decelerate the electrons output from the undulator 24 and accelerate the electrons output from the injector 21. As the electrons decelerate in the linear accelerator 22, some of their energy is transferred to the RF field in the linear accelerator 22. Therefore, the energy from the decelerating electrons is recovered by the linear accelerator 22 and can be used to accelerate the electron beam E output from the injector 21. This configuration is known as the Energy Recovery Linear Accelerator (ERL).

In some embodiments of the lithography system LS, the radiation source SO can comprise a single free electron laser FEL. In such embodiments, the main beam B emitted from the radiation source SO may be a laser beam B _FEL emitted from a free electron laser _FEL . In other embodiments, the lithography system LS can include a plurality of free electron lasers. A plurality of laser beams B _FEL emitted from a free electron laser can be combined to form a single main beam B comprising radiation from a plurality of free electron laser FEL emissions.

It is desirable in the lithography system LS to regulate the dose of radiation provided by the lithography apparatus LA _a to the substrate W. The dose of radiation supplied to the substrate W depends on the power of the branched radiation beam B _a supplied to the lithography apparatus LA _a . Therefore, the dose of radiation can be controlled by controlling the power of the branch radiation beam B _a . In order to control the power of the branch radiation beam B _a , one or more radiation sensors RS (such as the radiation sensor RS shown in FIG. 1 ) may be used to measure the power of the branch radiation beam B _a and/or the main beam B . The radiation sensor RS can form part of a feedback system configured to control the power of the primary beam B and/or the power of the branched radiation beam B _a to regulate the dose provided at the substrate W. For example, the power of the primary beam B and/or the power of the branched radiation beam B _a can be adjusted in response to measurements by one or more radiation sensors RS to provide a branched radiation beam having the desired power. It may be (e.g.) by one or more attenuators arranged in the path of the main beam B and / or B _a branch of the light beam in the main beam to adjust the power of the B and / or branched power of the radiation beam B _a. The attenuator can be controlled to adjust the intensity of the primary beam B and/or the branched beam B _a in response to measurements by the radiation sensor RS to provide a branched radiation beam B _a having the desired power.

Further, in the lithography system LS, it is necessary to measure the position of the radiation beam propagating through the lithography system LS. For example, the radiation sensor RS can be utilized to measure the position of one or more radiation beams to check the alignment of the radiation beams. The radiation sensor RS that measures the position of the radiation beam can form part of a feedback system configured to control the alignment of the radiation beam. For example, the alignment and/or orientation of one or more optical components of the lithography system LS can be controlled in response to measurements of the position of the radiation beam. The radiation sensor RS can, for example, be configured to measure the position of the branch radiation beam B _a before the branch radiation beam B _a is provided to the lithography apparatus LA _a . In the branch of the radiation beam B _a case where the beam position from the positional deviation to be adjusted beam delivery (e.g.) one or more alignment and / or orientation of the optical system components of the BDS branch so as to correct the radiation beam B _a Positional deviation.

4 is a schematic illustration of a radiation sensor 101 suitable for use in a lithography system LS. Radiation sensor 101 is configured to measure the power and/or position of radiation beam 102. The radiation beam 102 can be, for example, a main beam B emitted from the radiation source SO or can be a branch radiation beam B _a . Figure 4 has a Cartesian coordinate in which the z-direction represents the direction of propagation of the radiation beam 102.

The radiation sensor 101 has a portion of the beam conduit 105 along which the radiation beam 102 propagates. The beam conduit 105 is provided with a first aperture plate 107a including a first opening 108a and a second aperture plate 107b including a second opening 108b. The aperture plates 107a, 107b and the beam conduit 105 together form a chamber 110 through which the radiation beam 102 propagates. The radiation beam 102 enters the chamber 110 through the first opening 108a, propagates through the chamber 110, and exits the chamber 110 through the second opening 108b.

The chamber 110 is adapted to contain a gas. The gas system is introduced into the chamber 110 by a gas supply 112. Gas is transferred from the gas supply 112 to the chamber 110 via the valve 114. Valve 114 can be a variable valve that is operable to adjust the rate at which gas is introduced into chamber 110. The chamber 110 is further provided with a pump 116 configured to pump gas out of the chamber 110. Pump 116 is operable to adjust the rate at which gas is pumped out of chamber 110. Pressure sensor 118 is configured to measure the pressure inside chamber 110. Gas supply 112, valve 114, and/or pump 116 may be controlled in response to measurement of pressure within chamber 110 (by pressure sensor 118) to maintain a desired pressure within chamber 110.

Gas supply 112, valve 114, pump 116, and pressure sensor 118 may together be considered as an example of a gas supply mechanism configured to supply gas into chamber 110. The gas supply mechanism can be configured to maintain a desired pressure inside the chamber 110. The gas supply mechanism may take other forms and may include more and/or different components than the gas supply mechanism shown in FIG. In general, the gas supply mechanism can include any device configured to supply gas into the chamber and/or maintain a desired gas pressure in the chamber.

The aperture plates 107a, 107b are used to define any airflow entering and/or exiting the chamber 110 along the beam conduit 105 by any airflow defined to the openings 108a and 108b in the aperture plates 107a, 107b. The definition of the flow of gas entering and/or exiting the chamber 110 along the beam conduit 105 can assist in maintaining the desired composition of gas and/or the desired pressure in the chamber 110. First and The second openings 108a, 108b remain open to allow the radiation beam 102 to propagate through the chamber 110.

The gas flow entering and/or exiting the chamber 102 through the beam conduit 105 can be further defined by the use of an impermeable material that substantially transmits the radiation beam 102 to cover the opening 108a. However, impermeable materials typically absorb a relatively large portion of EUV radiation. In embodiments where the radiation beam 102 is an EUV radiation beam, the use of an impermeable material to cover the first and second openings 108a, 108b can thereby cause undesirable loss of EUV radiation from the radiation beam 102 by absorption. Furthermore, in general, the EUV radiation beam in the lithography system LS has a relatively high power. Absorbing a relatively high power EUV radiation beam from the material covering the openings 108a, 108b can thus result in excessive heating of the material and/or damage to the material.

The airflow entering and/or exiting the chamber 102 through the beam conduit 105 can be further defined by providing additional aperture plates in the beam conduit 105. For example, a third aperture plate (not shown) may be positioned in the beam conduit 105 and to the left of the first aperture plate 107a as viewed in FIG. 4, and a fourth aperture plate (not shown) It can be positioned in the beam conduit 105 and to the right of the second aperture plate 107b as viewed in FIG. The gas pressure between the first aperture plate 107a and the third aperture plate and between the second aperture plate 107b and the fourth aperture plate can be controlled, for example, using one or more pumps and/or gas supplies to define access and / or the air flow leaving the chamber 110. For example, the volume between the first aperture plate 107a and the third aperture plate and the pressure in the volume between the second aperture plate 107b and the fourth aperture plate can be controlled to reduce the traverse of the first aperture plate 107a and the second The pressure difference of the aperture plate 107b thereby reduces any air flow through the first and second openings 108a, 108b.

As will be described in further detail below, in some embodiments, the desired gas pressure and composition in the chamber 110 of the radiation sensor 101 can be the same as the desired gas pressure and combination in the remainder of the beam conduit 105. Things. In such embodiments, the first and second aperture plates 107a, 107b may be absent, as there is no need to define airflow along the beam conduit 105. In such embodiments, the beam conduit 105 can be considered to form the chamber 110 by itself, the cavity Chamber 110 forms part of radiation sensor 101. A gas supply mechanism may be provided to supply gas into the beam conduit 105 and/or maintain a desired gas pressure within the beam conduit 105, thereby supplying gas to the chamber 110 of the radiation sensor RS and/or at the radiation The interior of the chamber 110 of the sensor RS maintains the desired pressure.

The radiation sensor 101 further includes a first electrode 121, a second electrode 122, and a third electrode 123 each located in the chamber 110. The third electrode 123 is not visible in FIG. 4 because it is located behind the second electrode 122 as viewed in FIG. The configuration of the second electrode 122 and the third electrode 123 will be explained below with reference to FIGS. 5 and 6.

The radiation sensor 101 includes an electronic component 125. The first electrode 121 is electronically connected to the electronic component 125 via the first connection member 131 , the second electrode 122 is electronically connected to the electronic component 125 via the second connection member 132 , and the third electrode is electronically connected via the third connection member 133 Groundly connected to the electronic component 125. The electronic component 125 is shown in more detail in Figure 6 and described further below.

FIG. 5 is a schematic illustration of the second electrode 122 and the third electrode 123 as viewed along the y-axis. The projection of the radiation beam 102 onto the second and third electrodes is also shown in FIG. The second electrode 122 and the third electrode 123 are configured such that the projection of the radiation beam 102 coincides with the third electrode 123 for the first portion 135 of the path of the radiation beam 102 and for the second portion 137 of the path of the radiation beam 102 The second electrodes 122 are coincident.

FIG. 6 is a schematic illustration of the first 121, the second electrode 122, and the third electrode 123 as viewed along the z-axis. An embodiment of the first connector 131, the second connector 132, and the third connector 133 between the electronic component 125 and the electrode and the electronic component 125 is also shown in FIG. The electronic component 125 includes a voltage source 141, a first voltmeter 143a, a second voltmeter 143b, a first resistor 145a, and a second resistor 145b. Voltage source 141 is configured to maintain a potential difference between first electrode 121 and second electrode 122 and is configured to maintain a potential difference between first electrode 121 and third electrode 123. For example, a potential difference of approximately 100 volts to 1000 volts may be maintained between the first electrode 121 and the second electrode 122 and the third electrode 123. The voltage source can be configured to maintain the first electrode 121 at a higher voltage than the second electrode 122 and the third electrode 123 (eg, This is indicated by the + and - symbols in Figure 6. The voltage source can be configured to maintain a potential difference between the first electrode 121 and the second electrode 122 that is substantially the same as the potential difference maintained between the first electrode 121 and the third electrode 123.

The electronic component 125 can include a connector (not shown) to the electrical ground. For example, the electronic component 125 can include a connector to the beam conduit 105. The beam conduit 105 can be connected to the ground. The connection to the beam conduit 105 ensures that the voltage of the electrodes in the chamber 110 is maintained relative to the beam conduit 105 and that uncontrolled charge is prevented from accumulating on the components of the radiation sensor RS. The connection to the beam conduit 105 can be made, for example, to the negative terminal of the voltage source 141.

143a by a first voltmeter configured to measure the voltage drop across the first resistor 145a, the voltage drop can be derived from the second current flow between the first electrode 121 and the second electrode 122 I _2. 143b by the second voltmeter configured to measure the voltage drop across the second resistor 145b, the voltage drop can be derived from the third current flow between the first electrode 121 and the third electrode 123 I _3. In the embodiment shown in FIG. 6 embodiment, the second current I ₂ is the current flowing through the second electrode 122, and the third current I ₃ is the current flowing through the third electrode 123. The first current I ₁ flows through the first electrode 121 and is equal to the sum of the second current I ₂ and the third current I ₃ .

A first voltmeter 143a, a first resistor 145a, 143b and a second voltmeter 145b together form a second electrical resistor sensor 147, the sensor 147 by electrically configured to measure the current flowing through the second electrode 122 and I ₂ flow The current I ₃ through the third electrode 123. In other embodiments, the inductive detector 147 can take other forms and can be configured to measure more or less than the inductive detector 147 shown in FIG. For example, in some embodiments, the inductive detector 147 can be configured to directly measure the first current I ₁ flowing through the first electrode 121. In addition to or as an alternative to the measurement of the second current I ₂ and/or the third current I ₃ flowing through the second electrode 122 and the third electrode 123, a direct amount of the first current I ₁ may be performed. Measurement. In general, the inductive detector is configured to measure the current flowing through at least one of the electrodes of the radiation sensor RS.

As the radiation beam 102 passes through the chamber 110, the radiation beam 102 collides with gas molecules in the chamber and causes ionization of the gas, causing the generation of positively charged ions and free electrons. A potential difference between the first electrode 121 and the second electrode 122 and a potential difference between the first electrode 121 and the third electrode 123 cause free electrons to be attracted to the first electrode 121 and cause ions to be attracted to the second electrode 122 or the third Electrode 123. The flow of electrons to the first electrode 121 and the flow of ions to the second electrode 122 and the third electrode 123 cause a second current I ₂ flowing between the first electrode 121 and the second electrode 122 and at the first electrode 121 The third current I ₃ flowing between the third electrodes 123.

The second current I ₂ flowing between the first electrode 121 and the second electrode and the third current I ₃ flowing between the first electrode 121 and the third electrode 123 depend on ions and electrons in the chamber 110 The rate at which the gas is ionized. The rate at which ions and electrons are formed by ionization of the gas in chamber 110 depends on the ionized cross section of the gas in the chamber and the power of the radiation beam 102. An increase in the power of the radiation beam will result in an increase in the rate at which ions and electrons are formed by ionization of the gas in chamber 110, thereby causing an increase in the first, second, and third currents flowing through the electrode. Thus, the measurement of the second current I ₂ and the third current I ₃ flowing between the electrodes by the inductive detector 147 indicates the power of the radiation beam 102 and can be used to determine the power of the radiation beam 102. In other embodiments, the first current I ₁ flowing through the first electrode 101 can be measured, and the first current I ₁ can be used to determine the power of the radiation beam 102.

The processor may be operable from the first current I _1, the second current I ₂ and / or the third current I ₃ of the measurement (performed by the electric sensor 147) determines that the power of the radiation beam 102 of radiation beam 151 is determined 102 power. Although the embodiment of the radiation sensor RS shown in Figures 4, 5, and 6 includes three electrodes, it will be appreciated that at least the arrangement of only two electrodes that maintain a potential difference and measure the current can be utilized to determine at least the radiation. The power of the beam 102. Some embodiments of the invention may thus only include a first electrode, a second electrode, a voltage source configured to maintain a potential difference between the first electrode and the second electrode, configured to measure flow through the first and the first An inductor of current of at least one of the two electrodes, and a processor operable to determine the power of the radiation beam 102 from the measured current flowing between the first electrode and the second electrode.

Referring again to Figure 5, it will be appreciated that the number of ions reaching the second electrode 122 relative to the number of ions reaching the third electrode 123 depends on the first portion 135 of the path of the radiation beam 102 and the second portion 137 of the path of the radiation beam 102. The relative length. For example, if the length of the first portion 135 decreases and the length of the second portion 137 increases, the number of ions reaching the third electrode 123 will decrease and the number of ions reaching the second electrode 122 will increase. Therefore, the second current I ₂ flowing through the second electrode 122 will increase and the third current I ₃ flowing through the third electrode 123 will decrease. The comparison of the second current I ₂ with the third current I ₃ thus indicates the relative length of the first portion 135 of the path of the radiation beam 102 and the second portion 137 of the path of the radiation beam 102.

7 is a schematic illustration of the second electrode 122 and the third electrode 123. On the second electrode 122 and the third electrode 123, the radiation beam 102 is shown to the electrode 122 at three different positions in the x direction for the radiation beam 102. Projection on 123. The first position of the radiation beam in the x direction forms a first beam 102a of the radiation beam onto the electrodes 122, 123, and the second position of the radiation beam in the x direction forms a second beam 102b of the radiation beam onto the electrodes 122, 132, And the third position of the radiation beam at the third direction in the x direction forms a radiation beam onto the third projection 102c on the electrodes 122,123.

The first projection 102a of the radiation beam coincides with the third electrode 123 for the first portion 135a of the path of the radiation beam and coincides with the second electrode 122 for the second portion 137a of the path of the radiation beam. The first position of the radiation beam is such that the length of the first portion 135a of the first projection 102a is approximately the same as the length of the second portion 137a of the first projection 102a. This may cause the first current I ₁ flowing between the first electrode 121 and the second electrode 122 to be approximately equal to the second current I ₂ flowing between the first electrode 121 and the third electrode 123.

The second position of the radiation beam that forms the second projection 102b onto the electrodes 122, 123 is shifted in the negative x direction relative to the first position of the radiation beam. This causes the first portion 135b of the second projection 102b to be longer than the first portion 135a of the first projection 102a and cause the second portion 137b of the second projection 102b to be shorter than the first portion 135a of the first projection 102a. The displacement of the radiation beam 102 from the first position to the second position in the x direction thus causes the third current I ₃ flowing through the third electrode 123 to increase and causes the second current I ₂ flowing through the second electrode 122 to decrease. .

The third position of the radiation beam that forms the third projection 102c onto the electrodes 122, 123 is shifted in the positive x direction relative to the first position of the radiation beam. This causes the first portion 135c of the second projection 102c to be shorter than the first portion 135a of the first projection 102a and causes the second portion 137c of the second projection 102b to be longer than the first portion 135a of the first projection 102a. Displacement of the radiation beam 102 from the first position to the third position in the x direction thus causes the third current I ₃ flowing through the third electrode 123 to decrease and cause the second current I ₂ flowing through the second electrode 122 to increase. .

As has been described above, the magnitude of the second current I ₂ flowing through the second electrode 122 relative to the magnitude of the third current I ₃ flowing through the third electrode 123 depends on the position of the radiation beam in the x direction. The amount of the second current I ₂ measured can thus be measured with the third current I ₃ of comparator 102 to determine the position of the radiation beam in the x-direction. The position x of the radiation beam 102 in the x direction can be given by: x = k ( I ₃ - I ₂ ) / ( I ₂ + I ₃ ) (3)

Where k is the proportionality constant.

The radiation beam 102 can be determined by the processor 151 operable to compare the second current I ₂ with the third current I ₃ and determine the position of the radiation beam 102 in the x direction from the comparison (eg, by using equation (3)) Position x .

In practice, the radiation beam 102 has a diameter that extends in the x-direction, and thus, the radiation beam 102 is not limited to a single position in the x-direction. Therefore, the electrons and ions reaching the electrode are not limited to a single position in the x direction. The position x of the radiation beam 102 given by equation (3) is the average position of the radiation beam 102 in the x direction.

Since the radiation beam 102 has such that the electrons and ions reaching the electrode are not limited to the diameter extending in the x direction at a single position in the x direction, the electrons and ions reaching the electrode have a spread Δ x in the x direction. In addition to the spread of electrons and ions caused by the diameter of the radiation beam 102, electrons and ions can be further spread in the x direction before reaching the electrode. The spread Δ x' of electrons and ions occurring in the x direction after ionization and before electrons and ions reach the electrode is given by:

Where H is the degree of separation in the y direction between the first electrode 121 and the second and third electrodes, m is the mass of ions or electrons, E is the intensity of the electric field between the electrodes, and e is the charge of ions or electrons And v is the initial velocity of ions or electrons after ionization.

It is determined that all the variables of the spread Δ x ' given by the equation (4) in the x direction are the same for the ion and the electron system, but the mass m of the ion and the electron and the initial velocity of the ion and electron after the ionization v except. The quality of the electrons is 9.1 × 10 ^-31 kg. The quality of an ion depends on the chemical element that has been ionized but is still several orders of magnitude heavier than the electron. For example, in one embodiment, the gas in chamber 110 contains hydrogen gas that results in the formation of hydrogen ions having a mass of about 1.7 x ^10-27 kg. The initial velocity of the ions after ionization is a combination of the thermal velocity before ionization and the recoil velocity resulting from collision with photons in the radiation beam 102. The initial velocity of electrons after ionization depends on the energy absorbed by photons that ionize electrons from atoms. Due to the requirement that the higher mass and momentum of the ions be conserved during the ionization event than the electrons, in general, the initial velocity of the ions after ionization is less than the initial velocity of electrons after ionization. For example, in one embodiment, the initial velocity of ions after ionization may be about 3.5×10 ⁻³ ms ⁻¹ , and the initial velocity of electrons after ionization may be about 5×10 ⁶ ms ^{− 1} .

In general, the higher initial velocity of the electron after ionization (compared to the initial velocity of the ion) and the larger mass of the ion (compared to the mass of the electron) are: the spread of the ion in the x direction Δx ' is smaller than the spread Δ x' of electrons in the x direction. For example, in one embodiment, the degree of separation H between the first electrode 121 and the second and third electrodes in the y direction is about 1 cm, and the intensity of the electric field E between the electrodes is about 1×10. ⁵ V m ^-1 , the initial velocity of ions after ionization is about 3.5 × 10 ^-3 ms ^-1 , the initial velocity of electrons after ionization is about 5 × 10 ⁶ ms ^-1 , and the mass of electrons is 9.1 ×10 ^-31 kg, and the mass of the ions is about 1.7 × 10 ^-27 kg. In this embodiment, the spread Δ x' in the x direction caused by electrostatic repulsion of ions is about 0.08 mm, and the spread Δ x' in the x direction caused by electrostatic repulsion of electrons is about 2.7 mm. .

Show in the x direction of the ion △ x 'Electronics Show in comparison to the x direction of the △ x' by measuring small ion means a position in the x-direction compared to the electrons by measuring x The position in the direction can measure the position of the radiation beam 102 in the x direction to a better accuracy. It will be appreciated that the configuration of the electrodes shown in Figures 4-6 causes a measure of the position of the charged particles reaching the second electrode 122 and the third electrode 123 in the x-direction. Since the second electrode 122 and the third electrode 123 are kept at a lower voltage than the first electrode 121, the ions are incident on the second electrode 122 and the third electrode 123, and thus by comparing the second current I ₂ with The third current I ₃ determines the position of the ions in the x direction. It is therefore advantageous to maintain the second electrode 122 and the third electrode 123, which cause the determination of the position of the radiation beam 102, at a lower voltage than the first electrode 121 (i.e., a voltage having a small negative value and a small positive value). In order to improve the accuracy of determining the position of the radiation beam 102.

Although the spread of ions reaching the second electrode 122 and the third electrode 123 (in the x direction) may be about 0.1 mm or more (due to the diameter of the radiation beam and the spread Δx of the ions before reaching the electrode) The combined effect), but measuring the second current I ₂ and the third current I _{3 is} equivalent to averaging over a plurality of ions reaching the second and third electrodes. Therefore, the resolution of the determination of the position of the radiation beam 102 in the x direction can be practically less than 0.1 mm, as the position is determined as a result of averaging over many ions.

The first current I ₁ flowing through the first electrode 121 (that is, the sum of the second current I ₂ and the third current I ₃ ) is given by: I ₁ =( eεLpPλ )/( hc ) (5)

Where e is the charge of the electron (1.6 x 10 ^-19 C), ε is the absorption coefficient of the radiation beam 102 in the chamber 110, L is the length of the electrode in the z direction, p is the pressure in the chamber 110, P is The power of the radiation beam 102, λ is the wavelength of the radiation beam 102, h is the Planck constant (6.63 × 10 ^-34 m ² kg s ^-1 ), and c is the speed of light in the vacuum (3 × 10 ⁸ ms) ^-1 ). In one embodiment, the gas in the chamber may comprise hydrogen at a pressure of about 0.05 Pascal, the length L of the electrode in the z direction may be about 5 cm, and the wavelength λ of the radiation beam 102 may be about 13.5 nm, radiation. The power P of the beam 102 can be about 30 kilowatts, and the absorption coefficient ε of the radiation beam 102 in the chamber 110 can be about 1.2 x 10 ^-3 Pa ^-1 m ^-1 . In this embodiment, the first current I ₁ can be about 1 mA. The current of this magnitude can be readily measured using an accuracy sufficient to self-measure the power and/or position of the radiation beam 102.

The range over which the position of the radiant beam 102 can be measured and the resolution at which the measurement is performed depends on the configuration of the second electrode 122 and the third electrode 123. For example, in the configuration of the second electrode 122 and the third electrode 123 shown in FIG. 5, the second electrode 122 has a first straight edge 122a and the third electrode 123 has a second straight edge 123a. The first straight edge 122a and the second straight edge 123a are configured to intersect the projection of the radiation beam 102 to the second and third electrodes. In the configuration shown in FIG. 5, the first straight edge 122a is parallel to the second straight edge 123a and intersects the projection of the radiation beam 102 to the electrode to form between the first and second edges and the projection of the radiation beam 102. Angle α . The electrode ranges of the second and third electrodes in the x direction are equal to L tan α, where L is the length of the electrode in the propagation direction (z direction) of the radiation beam. The range over which the position of the measurable radiation beam 102 traverse is thus approximately L tan α (assuming a relatively small gap between the first edge 122a and the second edge 123a). Therefore, by increasing the length L of the electrodes and / or increasing the angle α to increase the range of the traverse position of the measurement radiation beam 102.

The resolution of the position of the radiation beam 102 (in the x direction) depends on the change in the length of the first portion 135 of the path of the radiation beam 102 that coincides with the third electrode 123 and the radiation beam that coincides with the second electrode 122. The change in length of the second portion 137 of the path of 102 is caused by a change in the given position of the radiation beam 102 in the x direction. That is, the resolution of the measurement depends on the sensitivity of the length of the first portion 135 and the second portion 137 to the change in position of the radiation beam 102 in the x direction. The sensitivity of the length of the first portion 135 and the second portion 137 to the change of the position of the radiation beam 102 in the x direction is Proportionate. Therefore, the angle α can be increased to increase the resolution of the measurement. The angle α may be the length L is set and the electrodes is determined by measuring position in order to bring the radiation beam 102 and the desired range resolution.

In some embodiments, more than three or three or fewer electrodes may be configured in the radiation sensor RS. Figure 8 is a schematic illustration of an embodiment of a radiation sensor comprising four electrodes (as viewed along the z-axis). The radiation sensor shown in FIG. 8 includes a second electrode 122 and a third electrode 123 that are identical to the second electrode 122 and the third electrode 123 depicted in FIGS. 4-6. However, the radiation sensor shown in FIG. 8 differs from the embodiment shown in FIGS. 4-6 in that the first electrode 121 is split into separate first and second electrodes 121, 124.

The first electrode 121 is provided with a first electrical connection 131 to the electronic component 125 and the fourth electrode 124 is provided with a fourth electrical connection 134 to the electronic component 125 . The electronic component 125 includes a configuration to maintain a potential difference between the first electrode 121 and the second electrode 122 and the third electrode 123 and is configured to maintain between the fourth electrode 124 and the second electrode 122 and the third electrode 123 A voltage source of potential difference (not shown in Figure 8). The electronic component 125 further includes an inductive detector (not shown in FIG. 8) configured to measure at least one current flowing through at least one of the electrodes 121, 122, 123, 124. The electronic component 125 used in conjunction with the embodiment shown in FIG. 8 can be configured similar to the electronic component 125 shown in FIG. 6, or can include different configurations of electrical components.

The first electrode and the fourth electrode may be configured similarly to the second electrode 122 and the third electrode 123. That is, the first and fourth electrodes can be configured such that the projections of the radiation beam 102 onto the first and fourth electrodes coincide with the first electrode for the first length and coincide with the fourth electrode for the second length, The first and second lengths vary depending on the position of the radiation beam 102 in the x direction. The measurement of the first current I ₁ flowing through the first electrode 121 and/or the measurement of the fourth current I ₄ flowing through the fourth electrode 124 can thus be used to pass the second and third flows similar to the above reference. The position of the radiation beam 102 in the x direction is determined in the manner described by the current of the electrodes.

Providing the separated first electrode 121 and the fourth electrode 124 may allow the first current I ₁ and the fourth current I ₄ flowing through the first electrode 121 and the fourth electrode 124 to be compared and flow through the second electrode 122 and The second current I _{2 of the} three electrodes 123 and the third current I ₃ are separated to determine the position of the radiation beam 102. Since the first electrode 121 and the fourth electrode 124 as compared to the second electrode 122 and the third electrode 123 held at a high (i.e., greater positive or large negative) voltage, so the first current I ₁ from And the fourth current I ₄ determines that the position of the radiation beam 102 is based on the electrons reaching the first electrode 121 and the fourth electrode 124, and determining the position of the radiation beam 102 from the second current I ₂ and the third current I ₃ based on the ion arrival The second electrode 122 and the third electrode 123.

Since the mass of the electrons is less than the mass of the ions, the electrons generated via ionization will experience an acceleration greater than the acceleration experienced by the ions under the influence of the electric field between the electrodes. Therefore, the electrons reach the second electrode 122 and the third electrode 123 before the ions reach the first electrode 121 and the fourth electrode 124. Therefore, the determination of the position of the radiation beam 102 based on the first current I ₁ and the fourth current I ₄ is comparable to the determination of the position of the radiation beam 102 based on the second current I ₂ and the third current I ₃ . Faster feedback at the location of 102. This may be advantageous in embodiments where the position of the radiation beam 102 is controlled by a feedback loop based on the measurement of the position of the radiation beam 102. A faster measurement of the position of the radiation beam 102 may allow for faster adjustment of the position of the radiation beam 102 in response to any change in the position of the radiation beam 102.

Although the measurement of the position of the radiation beam 102 based on the measurement of the electrons arriving at the electrode may be faster than the measurement of the position of the radiation beam 102 based on the measurement of the ions reaching the electrode (as described above), based on the amount of ions Measurements can be less accurate than electronic-based measurements. Thus, separate measurements based on the position of the ion and electron-based radiation beam 102, respectively, can be advantageous for different reasons.

Although the electrodes have been described above in connection with the measurement of the position of the radiation beam 102 in the x direction The particular configuration, but in other embodiments, the electrodes can be configured differently than the configurations described above. In general, any configuration of electrodes can be used in which the change in position of the radiation beam 102 causes a change in current flowing through the electrodes such that the measurement of the current flowing through the electrodes can be used to determine the position of the radiation beam 102.

In general, chamber 110 of radiation sensor RS in accordance with an embodiment of the present invention can be considered to be configured to extend generally along a first opening 108a and a second opening 108b of chamber 110. The beam axis receives the radiation beam 102. The beam axis may, for example, coincide with the path of the radiation beam 102 shown in Figures 4-6. The electrodes in the radiation sensor can be configured such that the projection of the beam axis onto the electrode coincides with a different electrode for different portions of the projection. The electrodes can be configured such that a change in position of the beam axis causes a change in the length of a different portion of the projection that coincides with the different electrodes, thereby causing a change in current flow through the electrodes.

Although the position of the radiation beam 102 in the x-direction is measured by the radiation sensor RS, it will be appreciated that it can be configured by using a configuration similar to that shown in Figures 4-6 or 8 but configured The radiation beam measures the position of the radiation beam in one or more other directions in an electrode configuration in a position other than the x direction in the direction of love.

For example, the radiation sensor may further include a fifth electrode, a sixth electrode, and a seventh device configured in a manner similar to the first, second, and third electrodes but rotated by 90 degrees around the propagation direction of the radiation beam 102. electrode. That is, the fifth, sixth, and seventh electrodes may extend substantially in the y and z directions with respect to the first, second, and third electrodes extending substantially in the x and z directions. The voltage source can be configured to maintain a potential difference between the fifth electrode and the sixth electrode and maintain a potential difference between the fifth electrode and the seventh electrode. The radiation sensor can further include an inductance detector configured to measure a current flowing through the sixth electrode and a current flowing through the seventh electrode. The current flowing through the sixth and seventh electrodes can be compared in a manner similar to that described above for comparing the second current I ₂ with the third current I ₃ to determine the position of the radiation beam 102 in the x direction to determine that the radiation beam 102 is The position in the y direction. The position of the radiation beam 102 in the y-direction can be determined by the processor 151 operable to compare the current flowing through the sixth and seventh electrodes and determining the position of the radiation beam 102 from the comparison.

Although the embodiments in which the fifth, sixth, and seventh electrodes are configured to determine the position of the radiation beam 102 in the y-direction have been described above, it will be appreciated that more electrodes may be provided to determine the radiation beam 102 in the y-direction. position. For example, the radiation sensor can further include an eighth electrode that can be held at a potential difference with respect to the sixth and seventh electrodes, and can be configured such that comparing the current flowing through the fifth and eighth electrodes can allow for further determination The position of the radiation beam 102 in the y-direction.

Although the embodiments described above are described with reference to a single voltage source that maintains a potential difference between different electrodes, the voltage source can actually include a plurality of voltage supplies. For example, the first voltage supply may maintain a potential difference between the first electrode and the second electrode, the second voltage supply may maintain a potential difference between the first electrode and the third electrode, and the third voltage supply may be in the A potential difference is maintained between the fourth electrode and the fifth electrode, and the fourth voltage supply maintains a potential difference between the fourth electrode and the sixth electrode. Alternatively, one or more voltage supplies can be configured to maintain a potential difference between a pair of electrodes.

Although a particular embodiment of the electronic component 125 is depicted in FIG. 6 and described above, the electronic component 125 can take other forms. For example, Figure 9 is a schematic illustration of an alternate embodiment of an electronic component 125'. The embodiment of the electronic component 125' is configured to be electrically connected to the first shown in FIG. 7 via the first electrical connector 131, the second electrical connector 132, the third electrical connector 133, and the fourth electrical connector 124. The arrangement of the electrode 121, the second electrode 122, the third electrode 123, and the fourth electrode 124. However, it will be appreciated that the electronic component 125' shown in Figure 9 can be adapted for connection to different configurations of electrodes. For example, the electronic component 125' shown in FIG. 9 can be adapted for connection to the first electrode 121, the second electrode 122, and the third electrode 123 shown in FIGS. 4-6.

In the embodiment of the electronic component 125' shown in FIG. 9, the electrical connectors 131, 132, 133, 134 from the electrodes 121, 122, 123, 124 (not shown in FIG. 9) are each held relative to the beam. The potential difference of the conduit 105. The first voltage supply 441a is coupled between the beam conduit 105 and the first electrical connector 131 and the fourth electrical connector 134, and is configured to maintain a potential difference between the first electrode 121 and the beam conduit 105 and A potential difference is maintained between the fourth electrode 124 and the beam conduit 105. 447a through the first current sensor configured to measure a first current I flowing between the first electrode 121 and the beam 105 of the catheter ₁ and thus measure the flow of current through the first electrode 121. In the embodiment shown in FIG. 9, first current sensor 447a takes the form of a first resistor 445a and a first voltmeter 443a configured to measure the voltage across first resistor 445a drop. However, in other embodiments, the first current sensor 447a can take other forms.

447d through the fourth current sensor configured to measure a current of the fourth current flowing between the electrode 124 and the fourth beam 105 conduit I _4, and thus the measurement of the flow through the fourth electrode 124. In the embodiment shown in FIG. 9, fourth current sensor 447d takes the form of a fourth resistor 445d and a fourth voltmeter 443d configured to measure the voltage across the fourth resistor 445d. drop. However, in other embodiments, the fourth current sensor 447a can take other forms.

The second voltage supply 441b is coupled between the beam conduit 105 and the second electrical connector 132 and the third electrical connector 133, and is configured to be between the second electrode 122 and the beam conduit 105 and the third electrode A potential difference is maintained between 123 and the beam conduit 105. 447b by the second current sensor configured to measure a second current flowing between the electrode 122 and second 105 conduit beam I _2, and thus measure the flow of current through the second electrode 122. In the embodiment shown in FIG. 9, the second current sensor 447b takes the form of a second resistor 445b and a second voltmeter 443b configured to measure the voltage across the second resistor 445b. drop. However, in other embodiments, the second current sensor 447b can take other forms.

447c via a third current sensor configured to measure the current flow between the third 105 and the third electrode 123 beamguide I _3, and thus measure the flow of current through the third electrode 123. In the embodiment shown in FIG. 9, third current sensor 447c takes the form of a third resistor 445c and a third voltmeter 443c configured to measure the voltage across third resistor 445c drop. However, in other embodiments, the second current sensor 447c can take other forms.

The beam conduit 105 acts as an electrical ground and can, for example, be connected to ground. The first voltage supply 441a and the second voltage supply 441b are configured to maintain a difference between the first and fourth electrodes 121, 124 and the beam conduit 105 than at the second electrode 122 and the third electrode 123 and the beam The potential difference of the potential difference maintained between the conduits 105. Accordingly, the first and second voltage supplies 441a and 441b are configured to maintain a potential difference between the first and fourth electrodes 121, 124 and the second electrode 122 and at the first and fourth electrodes 121, 124 and third The potential difference is maintained between the electrodes 123 by maintaining a potential difference between the electrodes and a common ground (which is the beam conduit 105 in the embodiment shown in Figure 9). Therefore, the first voltage supplier 441a and the second voltage supplier 441b can be regarded together as an example of a voltage source that maintains a potential difference between the electrodes.

The first current sensor 447a, the second current sensor 447b, the third current sensor 447c, and the fourth current sensor 447d can be considered together to be configured to measure at least one of the flow through electrodes An example of an electrical current sensor.

Measuring, by the first current I ₁ , the second current I ₂ , the third current I _{3 ,} and the fourth current I ₄ flowing through the first electrode 121 , the second electrode 122 , the third electrode 123 , and the fourth electrode 124 respectively A current sensor 447a, a second current sensor 447b, a third current sensor 447c, and a fourth current sensor 447d provide input to the processor 151. From the above discussion of the current flowing between the electrodes in the embodiment shown in Figure 6, it will be appreciated that the first current I ₁ , the second current I ₂ , the third current I _{3 ,} and the fourth current I ₄ each indicate a radiation beam The power of 102, and the comparison of the second current I ₂ with the third current I ₃ and/or the comparison of the first current I ₁ and the fourth current I ₄ indicates the position of the radiation beam 102 in the x direction. The processor 151 is operable to determine the power of the radiation beam 102 and the position of the radiation beam 102 in the x direction from the first, second, third, and fourth currents.

Other embodiments of the radiation sensor RS can include different embodiments than those shown in the embodiment of FIG. An electronic component of the electronic component, and may include an electronic component other than the electronic component shown in FIG. In general, the voltage source is configured to maintain a potential difference between the electrodes in the radiation sensor RS. The potential difference can be applied, for example, directly between the electrodes (as shown in Figure 6), or can be applied between the electrodes and a common ground such as beam conduit 105 (as shown in Figure 9). The voltage source can, for example, comprise a single voltage supply, as shown in Figure 6, or can include a plurality of voltage supplies, as shown in Figure 9. At least one inductive detector is configured to measure current flowing through at least one of the electrodes. The current flowing through the electrodes can be measured, for example, by measuring the current flowing between the electrodes (as shown in Figure 6), or can be measured, for example, by electrodes in conjunction with, for example, beam conduit 105. The current flowing between the grounds (shown in Figure 9) is measured.

It will be appreciated that the electronic component 125' shown in Figure 9 can be adapted for embodiments that do not include a fourth electrode as described above. Additionally or alternatively, the electronic component 125' shown in Figure 9 can be adapted for embodiments including fifth, sixth, and seventh electrodes configured to determine the position of the radiation beam 102 in the y-direction. The electronic component 125' shown in Figure 9 can be further adapted to an embodiment further comprising an eighth electrode configured to determine the position of the radiation beam in the y-direction.

As will be appreciated from the described embodiments, an electrode can be disposed in the radiation sensor RS to measure at least one of the power of the radiation beam 102, the position of the radiation beam in the x-direction, and the position of the radiation beam in the y-direction. . In some embodiments, the electrodes can be configured to measure all three of the equal amounts. In these embodiments, the power of the radiation beam and the location of the radiation in a plane perpendicular to the direction of propagation of the radiation beam 102 are determined.

As has been described above, the gas in chamber 110 is ionized by radiation beam 102 and the resulting ions and electrons travel under the influence of the electric field in chamber 110 resulting from the potential difference maintained between the electrodes in chamber 110 to One of the electrodes. Ionization of the gas in the chamber thus causes the gas to be removed from the region of the chamber 110 through which the radiation beam 102 propagates. The region of the chamber 110 for removing gas by ionization and transport of the resulting ions to the electrodes may be referred to as phase The interaction zone 153, which is generally shown in Figure 6 as a dashed circle.

The transmission of the radiation beam 102 through the chamber 110 thus results in a temporary reduction in the amount of gas present in the interaction zone 153. Typically, the radiation beam 102 is a pulsed radiation beam comprising a series of radiation pulses. The passage of the radiation pulse through the chamber 110 causes the amount of gas in the interaction zone 153 to decrease. Between the radiation pulses, the amount of gas in the interaction zone 153 can be at least partially replenished attributable to the gas from the zone surrounding the interaction zone 153 traveling into the interaction zone 153. The amount of gas present in the interaction zone 153 for the subsequent radiation pulse (after the reduction of the gas in the interaction zone 152 caused by ionization and subsequent replenishment of the gas from the zone surrounding the interaction zone 153) depends on the cavity The ionized cross section of the gas in chamber 110, the composition of the gas, the power of the radiation beam, and the time interval between successive pulses of radiation.

It is known that radiation sensors typically utilize a gas having a relatively high ionization cross section in order to ensure that the amount of gas ionized by the radiation beam having a given power is relatively large and thus ensures that the flow through the electrodes in the radiation sensor is achieved. The current is relatively large. For example, a gas such as helium may be used in the radiation sensor. Helium has a relatively high ionization cross section and is typically used in radiation sensors at relatively low pressures, such as a pressure of 1 x 10 ^-4 Pascals.

For some applications, it may be desirable to use a gas having a relatively high ionization cross section at relatively low pressures. However, in, for example, the lithography system LS, the radiation beam 102 measured by the radiation sensor RS can have relatively high power and can pulsate with relatively high repetition rates. For example, the radiation beam 102 can have a power of approximately 30 kilowatts. Radiation beam 102 can, for example, have a pulse repetition rate of approximately 375 megahertz. A relatively high power radiation beam can cause a relatively large amount of gas to be ionized by each pulse of the radiation beam, and thus a relatively large amount of gas is removed from the interaction zone 153 by each pulse. A radiation beam having a relatively high repetition rate causes a relatively short time interval between each pulse of the radiation beam, and thus a relatively short time interval during which the gas can be applied between the pulses of the radiation beam 102 to supplement the interaction region 153.

The large amount of gas removed from the interaction zone 153 by each pulse of the radiation beam 102 and the small time interval during which the gas can be replenished between pulses can cause the interaction zone 153 to be insufficiently supplemented between the pulses of the radiation beam 102. For example, after the first pulse of the radiation beam has passed through the interaction zone 153, the amount of gas in the interaction zone 153 is reduced and may not be sufficiently replenished before the second pulse of the radiation beam passes through the interaction zone. The gas present in the interaction zone 153 during the second pulse propagation through the interaction zone 153 is less than the gas present in the interaction zone 153 during the first pulse propagation through the interaction zone 153. Further subsequent radiation pulses may further reduce the amount of gas present in the interaction zone 153, which may result in a lack of gas in the interaction zone 153.

The reduction in the amount of gas present in the interaction zone 153 reduces the number of ionization events caused by the radiation pulses transmitted through the interaction zone 153. Reducing the number of ionization events causes a reduction in the number of ions and electrons due to ionization of the gas, and thus reduces the current flowing between the electrodes in the radiation sensor. The reduction in current flowing between the electrodes amounts to a reduction in the signal for the power and/or position of the radiation sensor RS radiation beam. Therefore, the radiation sensor RS determines the signal-to-noise ratio reduction of power and/or position, thereby reducing the accuracy of the determination. The current flowing between the electrodes can be reduced, for example, by the depletion of gas in the interaction zone 153 to such an extent that the determination of the power and/or position of the radiation beam is no longer possible.

Further, the consumption of gas in the interaction zone 153 may not be spatially uniform across the interaction zone 153. The change in intensity of the radiation beam 102 across its cross-section can result in a change in the amount of gas ionized at different locations in the interaction zone 153. For example, the radiation beam 102 propagating through the radiation sensor can have an approximate Gaussian cross-sectional intensity distribution that is greater at the center of the beam cross-section than at its edges. This radiation beam 102 can result in a level of depletion at the center of the interaction zone 153 that is greater than at the edge. Thus, the determination of the position of the radiation beam 102 can be weighed against the edge of the range of radiation beams 102 that are present for more gases that are ionized, thereby reducing the accuracy of the determination.

In order to overcome the above problems associated with the measurement of radiation beams having relatively high power and/or relatively high repetition rates, one aspect of the invention contemplates the use of a radiation sensor in which hydrogen is introduced to the radiation sensor RS. In the chamber 110. In some applications, the radiation beam 102 measured by the radiation sensor RS is an EUV radiation beam. At the EUV wavelength, the ionized cross section of hydrogen is smaller than the ionized cross section of a gas commonly used in known radiation sensors. For example, at the EUV wavelength, the ionized cross section of hydrogen is about 400 times smaller than the ionized cross section of helium. The relatively small ionization cross section of hydrogen means that less ionization events occur due to the transmission of radiation pulses of a given power through the interaction zone 153. Thus, the amount of gas removed from the interaction zone 153 by each of the radiation pulses is reduced, and more gas remains in the interaction zone 153 for ionization of subsequent radiation pulses.

In addition to the ionized cross-sectional reduction of hydrogen, hydrogen is also lighter than gases used in known radiation sensors. The reduction in the mass of hydrogen (as compared to other gases) means that at a given temperature and pressure, hydrogen has a higher velocity than other gases. For example, at a given temperature and pressure, the velocity of hydrogen can be about eight times greater than the velocity of helium. An increase in the velocity of hydrogen compared to other gases means that after the radiation pulse passes through the interaction zone 153 and the gas is removed from the interaction zone 153, the interaction zone 153 is replenished at an increasing rate compared to the other gases. Thus, in the case of hydrogen, the extent of the amount of gas in the interaction zone 153 is increased between the radiation pulses transmitted through the interaction zone 153 as compared to other gases, such as helium.

As has been described above, the use of hydrogen in the radiation sensor RS causes the removal of the reduced amount of gas from the interaction zone 153 by each radiation pulse and increases the complementary interaction between the radiation pulses transmitted through the interaction zone 153. The rate of gas in zone 153. This advantageously allows the radiation beam with higher power and repetition rate to be measured by the radiation sensor RS, while the gas in the interaction zone 153 is not depleted to the extent that the accuracy of the measurement is significantly reduced.

Figure 10 is a schematic representation of the steady state gas pressure in the interaction zone 153 as a function of the repetition rate of the radiation beam 102 transmitted through the interaction zone in the radiation sensor RS, radiation The sensor RS includes a chamber 110 into which hydrogen is introduced. The gas pressure in the interaction zone 153 is shown in Figure 10 as a percentage of the gas pressure in the remainder of the chamber 110. The dashed line shown in Figure 10 represents a repetition rate of 375 megahertz, which may, for example, be the repetition rate of the EUV radiation beam in the lithography system LS. As can be seen from Figure 10, the steady state gas pressure at a repetition rate of 375 megahertz is close to 100% of the pressure in the remainder of the chamber (and can be, for example, about 99.5%). Therefore, the gas removed from the interaction zone 153 due to ionization is almost completely replenished between the pulses of the radiation beam, such that the pressure in the interaction zone 153 is not significant for subsequent radiation pulses propagating through the interaction zone 153. Reduction. The radiation sensor RS, which is introduced into the chamber in the radiation sensor RS using hydrogen, thus advantageously allows the measurement of the position and/or power of the radiation beam having a relatively high power and/or repetition rate.

As explained above, hydrogen has a smaller ionized cross section than a gas used in known radiation sensors. The ionized cross-sectional reduction of hydrogen means that the number of ionization events resulting from a single radiation pulse is reduced at a given gas pressure and for a given power of the radiation beam compared to other gases, and thus in the sensor The current flowing between the electrodes is reduced. However, as described above, the use of hydrogen advantageously reduces the extent to which the gas is depleted by the radiation pulse, and therefore, for subsequent radiation pulses, more ionization events can occur when hydrogen is used than when other gases are used. . It is therefore advantageous to increase the current flowing between the electrodes due to subsequent radiation pulses.

An additional advantage of using hydrogen in a radiation sensor is that hydrogen can serve other useful purposes in the beam conduit through which the radiation beam propagates. For example, hydrogen can be introduced into the beam conduit to remove contaminants from the optical components in the beam conduit. Propagation of the radiation beam through the hydrogen gas can result in the formation of hydrogen ions and/or hydrogen groups. If the hydrogen ions are subjected to an electric field, such as a condition between the electrodes in the radiation sensor RS, the hydrogen ions are attracted to one of the electrodes and recombine with the electrons at one of the electrodes. However, in other parts of the beam conduit, the hydrogen ions are not subjected to an electric field and are not attracted to the electrodes. Radiation beam 102 is passed through containing hydrogen The beam conduit 105 can thus result in the presence of free hydrogen ions and/or hydrogen radicals in the beam conduit 105.

Hydrogen ions and hydrogen groups are highly reactive and can therefore react with other materials within the beam conduit 105. For example, particles may be present in the beam conduit 105, which may become deposited onto optical components (eg, mirrors) in the beam conduit 105, causing undesirable contamination of the optical components. The hydrogen ions or hydrogen groups present in the beam conduit 105 can react with the contaminants to form a gaseous compound having hydrogen. Gaseous compounds including contaminants can then be pumped out of the beam conduit 105 by a pump to remove contaminants from the beam conduit 105. Hydrogen can thus be usefully introduced into the beam conduit 105 to clean the components located in the beam conduit 105.

In some embodiments, hydrogen can thus be introduced into the beam conduit 105 for other advantageous purposes. In this embodiment, a gas supply mechanism for separation of the radiation sensor RS may not be required, and instead, a gas supply system that supplies hydrogen to the beam conduit 105 may serve as a gas supply system for the radiation sensor. In such embodiments, an aperture plate may not be required to form a separate chamber in the radiation sensor RS, and the chamber of the radiation sensor may be formed solely by the beam conduit 105. This can advantageously reduce the complexity and/or cost of the radiation sensor RS.

The pressure of the hydrogen within the chamber 110 forming part of the radiation sensor RS can be controlled by a gas supply mechanism to maintain the desired hydrogen pressure inside the chamber. The desired hydrogen pressure inside the chamber can depend on several factors. For example, increasing the hydrogen pressure inside the chamber can increase the number of ionization events that occur for each of the radiation pulses transmitted through the radiation sensor RS. This can result in a corresponding increase in the current flowing between the electrodes in the radiation sensor RS, thereby advantageously increasing the magnitude of the signal upon which the determination of the power and/or position of the radiation beam is based.

In some embodiments, the gas supply mechanism can supply hydrogen to the chamber 110 of the radiation sensor RS to maintain a pressure greater than about 0.01 Pascals in the chamber. In some real In an embodiment, the gas supply mechanism can maintain a hydrogen pressure greater than about 0.1 Pascals in chamber 110.

However, at a certain hydrogen pressure in the chamber 110, the potential difference between the electrodes in the chamber can induce a Paschen discharge between the electrodes. Discharge between the electrodes can induce the formation of ions and electrons, which can result in establishing a conductive path between the electrodes. The Paschen discharge can therefore adversely affect the measurement by the radiation sensor RS (and can render any such measurement impossible), and therefore requires hydrogen to be maintained inside the chamber that is less than the pressure at which the Paschen discharge occurs. pressure.

The pressure inside the chamber at which the Paschen discharge occurs depends on the potential difference between the electrodes, the composition of the gas between the electrodes, the degree of separation between the electrodes, and the shape of the electrodes. In embodiments where the gas in chamber 110 is hydrogen, a potential difference greater than about 270 volts between the electrodes (or between the electrodes and another component (eg, beam conduit 105) may result in some pressure and electrode configuration. Pashen discharge. For example, at a resolution between about 10 Pascals and about 15 cm of the electrode, a potential difference of about 270 volts or more between the electrodes can cause a Paschen discharge to occur. In some embodiments, it may therefore be desirable to maintain a hydrogen pressure of less than about 10 Pascals in the chamber to avoid Paschen discharge in the chamber. In other embodiments (eg, where different gases are used, where there is greater separation between the electrodes, and/or where there is a small potential difference between the electrodes), a pressure greater than 10 Pascals can be maintained in the chamber while Passon discharge is still avoided. In some embodiments, the pressure inside the chamber can be less than about 100 Pascals.

In some embodiments, the separation between the electrodes can be less than about 15 centimeters, and/or the potential difference between the electrodes can be greater than about 270 volts. In such embodiments, it may be desirable to maintain a pressure of significantly less than 10 Pascals inside the chamber. For example, the pressure in the chamber can be maintained at less than about 1 Pascal.

Although the advantages of using a gas having a relatively low ionization cross section have been described above in the context of the use of hydrogen, other gases having a low ionization cross section may result in the above. Refer to the same or similar beneficial effects described for hydrogen. For example, helium also has a relatively low ionization cross section for EUV radiation and can therefore be used equivalently in the radiation sensor RS.

In some embodiments, the radiation sensor can be adapted to measure a radiation beam 102 having a wavelength of approximately 13.5 nanometers. At a wavelength of 13.5 nm, the hydrogen ion having a cross-section of about 4.9 × 10 ^-24 m ^ of, and having a helium ionization cross-section of approximately 5.1 × 10 ^-23 square meters of. In comparison, helium gas that can be used in some radiation sensors has an ionized cross section of about 2.5 x 10 - ²¹ square meters.

In some embodiments, the radiation sensor can be adapted to measure a radiation beam 102 having a wavelength of about 6.75 nanometers. At a wavelength of 6.75 nm, hydrogen has an ionized cross section of about 5.9 x 10 ^-25 m 2 and xenon has an ionized cross section of about 7.7 x 10 ^-24 m 2 .

Although the advantages of using hydrogen or helium in the chamber forming part of the radiation sensor RS have been described above, other gases may alternatively be used in the radiation sensor RS. For example, a gas such as helium having a relatively high ionization cross section can be used in the radiation sensor RS. As described above, the use of a gas having a relatively high ionization cross section can result in a lack of gas in the interaction zone 153, which is ionized by the radiation beam 102 in the interaction zone 153. In particular, a radiation beam 102 having a relatively high power and/or relatively high repetition rate can cause a lack of gas in the interaction zone 153. The lack of gas in the interaction zone 153 reduces the number of ionization events caused by a given pulse of the radiation beam 102, and thus reduces the resulting current flowing between the electrodes in the radiation sensor RS. The reduction in current flowing between the electrodes reduces the magnitude of the signal used to determine the power and/or position of the radiation beam 102, and thus reduces the signal-to-noise ratio by which the decision is made.

As described above, one solution to this problem is to use a gas having a smaller ionized cross section, such as hydrogen or helium. An alternative solution to this problem is to increase the pressure of the gas in the chamber 110 that forms part of the radiation sensor RS. Increasing the pressure inside the chamber 110 results in an increase in the number of ionization events resulting from a given pulse of radiation transmitted through the chamber 110, thereby increasing the resulting current flowing between the electrodes. Since increasing the pressure inside the chamber increases the number of ionization events resulting from a given pulse of radiation, the amount of gas removed from the interaction zone 153 during each pulse is also increased. Despite the increased pressure of the gas, the interaction zone 153 can thus remain depleted. However, although the gas in the interaction zone 153 is depleted, the current flowing between the electrodes in the radiation sensor RS is increased by increasing the pressure of the gas in the chamber 110. Increasing the pressure therefore results in an increase in the magnitude of the signal upon which the determination of the power and/or position of the radiation beam is based and thus increases the signal to interference ratio by which the decision is made. For example, increasing the pressure of the chamber inside the chamber from, for example, a pressure of 1 x 10 ^-3 Pascals to a pressure of 0.1 Pascal increases the signal-to-noise ratio of the power and/or position of the radiation beam by about 100 times. .

Increasing the pressure inside the chamber 110 in the radiation sensor RS may thus advantageously allow the radiation sensor to be used to perform measurements of the position and/or power of the radiation beam having a relatively high power and/or repetition rate. For example, the power and/or position of the radiation beam propagating through the lithography system LS can be measured.

However, increasing the pressure inside the chamber 110 in the radiation sensor RS will increase the fraction of the absorbed radiation beam that propagates through the chamber. It is thus possible to control the pressure inside the chamber 110 in order to limit the attenuation of the radiation beam due to absorption.

In some embodiments, the radiation sensor RS can include a gas supply mechanism configured to maintain a gas greater than about 0.01 Pascals in the chamber 110. In some embodiments, the gas supply mechanism can be configured to maintain a gas greater than about 0.1 Pascal in the chamber. The gas can be any gas that is ionized by the radiation beam. The gas can, for example, contain helium. In some embodiments, the gas can comprise any noble gas. For example, the gas may comprise one or more of helium, neon, argon, helium, and/or helium. In some embodiments, non-rare gases such as nitrogen and/or oxygen may be used.

As explained above with reference to the use of hydrogen in the radiation sensor RS, with radiation The pressure of the gas in the chamber 110 of the sensor RS is increased to achieve a pressure that induces a Paschen discharge between the electrodes in the chamber. It is therefore necessary to maintain the gas in the chamber at a pressure below which the Paschen discharge is induced.

As explained above, the extent to which the gas is depleted in the radiation sensor depends on the power of the radiation beam. Thus, gas depletion in the radiation sensor RS can be reduced or avoided by measuring the radiation beam with reduced power. For example, this can be achieved by measuring only one portion of the radiation beam and using the measurement to derive one or more properties of the entire radiation beam.

11 is a schematic illustration of a configuration for measuring a portion of a radiation beam 202 using a radiation sensor RS. Beam splitter 205 is positioned in the path of radiation beam 202 and is configured to receive radiation beam 202 and split radiation beam 202 into first portion 203 and second portion 204. The second portion 204 of the radiation beam 202 is directed to a radiation sensor RS, which may take the form of, for example, the radiation sensor RS depicted in Figures 4-6. The radiation sensor RS is configured to measure the power and/or position of the second portion 204 of the radiation beam 202. The power and/or position of the second portion 204 indicates the power and/or position of the radiation beam 202, and thus can be used to determine the power and/or position of the radiation beam 202. The first portion 203 is used for the primary application of the radiation beam 202. For example, the first portion 203 or a portion of the first portion 203 can be provided to the lithography apparatus LA in the lithography system LS.

Beam splitter 205 can be configured to direct only a fraction of the power of radiation beam 202 to form second portion 204. For example, the second portion 204 can have a power of less than 1% of the power of the radiation beam 202. In some embodiments, the second portion can have a power of about 0.1% of the power of the radiation beam 202. Since the power of the second portion 204 is much less than the power of the radiation beam 202, the second portion 204 can be measured by the radiation sensor RS without causing gas depletion in the radiation sensor RS. Thus, measuring only a portion 204 of the radiation beam 202 can advantageously allow for determining the power and/or position of the high power radiation beam 202 (such as the EUV radiation beam in the lithography system LS) without causing gas in the radiation sensor RS. It is scarce.

Beam splitter 205 can, for example, comprise a diffraction grating that splits radiation beam 202 into a plurality of different diffraction orders. The second portion 204 of the radiation beam may represent a first diffraction order and the first portion 203 of the radiation beam may represent a zeroth diffraction order.

Although the second portion 204 is shown in FIG. 11 as propagating in a direction approximately perpendicular to the direction of propagation of the radiation beam 202 toward the beam splitter 205, in some embodiments, the second portion 204 can propagate in different directions. Moreover, although the first portion 203 of the radiation beam is shown in FIG. 11 to propagate substantially the same direction as the direction of propagation of the radiation beam 202 toward the beam splitter 205, in some embodiments, the first portion can be in different directions Spread on. For example, in some embodiments, beam splitter 205 can include a reflective grating. The reflective grating is reflective to form a zeroth diffraction order of the first portion 203 and is reflective to form a first diffraction order of the second portion 204 at a non-perpendicular angle.

In some embodiments, one or more measurements of the power and/or position of the radiation beam can be used to provide an input to a feedback loop that controls the power and/or position of the radiation beam. For example, the power of the radiation beam can be controlled (eg, using one or more attenuators) in response to the measurement of the power of the radiation beam to maintain the power of the radiation beam at the desired power. Similarly, the position of the radiation beam can be controlled (e.g., by controlling the alignment of one or more optical components) in response to measurements of the position of the radiation beam.

In some embodiments, the plurality of radiation sensors RS can be configured to measure the power and/or position of the radiation beam at multiple locations (eg, at multiple locations in the lithography system LS). For example, the first radiation sensor can be configured to determine at least one of power and position of the radiation beam at the first location, and the second radiation sensor can be configured to determine the radiation beam at the second location At least one of the power and location. The first radiation sensor can, for example, be configured to determine the position of the radiation beam at the first location, and the second radiation sensor can be configured to determine the location of the radiation beam at the second location. The position of the radiation beam at two or more locations along its propagation path can be used to determine the direction of propagation of the radiation beam between the two locations. For example, the processor can be configured to compare the radiation beam at The determined position at the first location and the determined position of the radiation beam, and the direction of propagation of the radiation beam can be determined from the comparison.

12 is a schematic illustration of a radiation sensor system 301 that includes a first radiation sensor RS ₁ and a second radiation sensor RS ₂ . The first radiation sensor RS ₁ is configured to measure one or more properties of the radiation beam 302 shortly after the radiation beam 302 has been emitted from the radiation source SO. Radiation sensor system 301 also includes a beam splitter 305 configured to split radiation beam 302 into first portion 303 and second portion 304. The second portion 304 is directed to the second radiation sensor RS ₂ .

Since the first radiation sensor RS ₁ is positioned relatively close to the radiation source SO, the radiation beam 302 propagating through the first radiation sensor RS ₁ can have a relatively high power and a relatively small cross section. The first light beam 302 of the radiation sensor RS ₁ and radiated high power may cause a relatively small cross-section of the gas consumption of the lack of a first radiation sensor RS _1. The measurement of the power of the radiation beam can be particularly sensitive to the gas in the radiation sensor, and the measurement of the position of the radiation beam can be less sensitive to the gas consumption in the radiation sensor. Since the first radiation sensor RS ₁ can experience gas depletion in the sensor, the first radiation sensor RS ₁ can be used to determine the position of the radiation beam 302, but not to determine the power of the radiation beam 302. Although the measurement of the position of the radiation beam can be less sensitive to the gas consumption in the radiation sensor, any spatial variability in the gas consumption occurring in the radiation sensor can reduce the accuracy of the measurement of the position of the radiation beam. degree.

The second portion 302 of the radiation beam 304 may represent a relatively small fraction of the power of the radiation beam 302, and thus may cause the second radiation sensor RS ₂ in little or no gas depleted. Since there may be little or no gas depletion in the second radiation sensor RS ₂ , the second radiation sensor RS ₂ may be adapted to determine the power of the second portion 304 of the radiation beam, from which the radiation beam 302 may be determined Power.

In the radiation sensor system 301 of FIG. 12 shows, so the first radiation sensor RS ₁ may determine the position of the radiation beam 302, and may be a second radiation sensor RS ₂ determines the power of the radiation beam 302. In some embodiments, the second radiation sensor RS ₂ can also determine the position of the second portion 304 of the radiation beam. The position of the radiation beam 302 determined by the first radiation sensor RS _{1 and} the position of the second portion 304 of the radiation beam determined by the second radiation sensor RS ₂ can be compared to determine the direction of propagation of the radiation beam 302.

Although embodiments have been described above for determining the position and/or power of a radiation beam propagating in the lithography system LS by the radiation sensor RS, embodiments of the radiation sensor RS as described herein can be used to determine Used for radiation beams in applications other than lithography.

Although the embodiment of the radiation source SO has been described and depicted as including a free electron laser FEL, the radiation source SO may include a radiation source other than a free electron laser FEL.

It should be understood that a radiation source comprising a free electron laser FEL can comprise any number of free electron laser FELs. For example, the radiation source can include more than one free electron laser FEL. For example, two free electron lasers can be configured to provide EUV radiation to a plurality of lithography devices. This system allows some redundancy. This may allow for the use of another free electron laser while one free electron laser is being repaired or undergoing maintenance.

The lithography system LS can include any number of lithography devices. For example, the number of lithographic devices that form the lithography system LS may depend on the amount of radiation output from the radiation source SO and the amount of radiation that is lost in the beam delivery system BDS. Additionally or alternatively, the number of lithography devices forming the lithography system LS may depend on the layout of a lithography system LS and/or the layout of the plurality of lithography systems LS.

Embodiments of the lithography system LS may also include one or more reticle inspection devices MIA and/or one or more Aerial Inspection Measurement Systems (AIMS). In some embodiments, the lithography system LS can include a plurality of reticle detection devices to allow for some redundancy. This may allow for the use of another reticle detecting device while one reticle detecting device is being repaired or undergoing maintenance. Therefore, a reticle inspection device is always available. The reticle detecting device can use a lower power radiation beam than the lithography device. In addition, it will be appreciated that radiation generated using a free electron laser FEL of the type described herein may be used. For applications other than lithography or lithography related applications.

It will be further appreciated that a free electron laser comprising an undulator as described above can be used as a radiation source for several applications including, but not limited to, lithography.

Embodiments of the invention have been described in the context of the content of a free electron laser FEL that outputs an EUV radiation beam. However, a free electron laser FEL can be configured to output radiation having any wavelength. Accordingly, some embodiments of the invention may include free electrons that output a radiation beam that is not an EUV radiation beam. As explained above, the ionization cross section of the gas depends on the wavelength of the radiation in question. The behavior of a particular gas that has been described in the context of EUV radiation may differ from the behavior already described at wavelengths that are not in the EUV range.

The term "EUV radiation" can be considered to encompass electromagnetic radiation having a wavelength in the range of 4 nanometers to 20 nanometers (eg, in the range of 13 nanometers to 14 nanometers). The EUV radiation can have a wavelength of less than 10 nanometers, for example, in the range of 4 nanometers to 10 nanometers, such as 6.7 nanometers or 6.8 nanometers.

The lithography devices LA _a to LA _n can be used in the manufacture of ICs. Alternatively, as described herein, the micro Movies to LA _n LA _a device may have other applications. Other possible applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, and the like.

Different embodiments may be combined with each other. Features of the embodiments may be combined with features of other embodiments.

Although the specific embodiments of the invention have been described hereinabove, it will be understood that the invention may be practiced otherwise. The above description is intended to be illustrative, and not restrictive. Therefore, it will be apparent to those skilled in the art that the present invention may be modified without departing from the scope of the appended claims. Other aspects of the invention are set forth in the following numbered clauses.

What is claimed is: 1. A radiation sensor comprising: a chamber for containing a gas, the chamber having a first opening and a second Opening, such that a radiation beam can enter the chamber through the first opening, propagate through the chamber and exit the chamber through the second opening; a gas supply mechanism configured to supply hydrogen or helium gas to In the chamber; a first electrode located in the chamber; a second electrode located in the chamber; a voltage source configured to be between the first electrode and the second electrode Maintaining a potential difference; an inductive detector configured to measure a current flowing through at least one of the first electrode and the second electrode, the current being caused by a radiation beam propagating through one of the chambers Causing ionization of the hydrogen or helium gas in the chamber; and a processor operative to determine from the measured current to propagate at least one of a beam of radiation from the chamber and at least one of a position One.

2. The radiation sensor of clause 1, wherein the gas supply mechanism is configured to maintain a desired hydrogen or helium pressure in the chamber.

3. The radiation sensor of clause 2, wherein the gas supply mechanism is configured to maintain a hydrogen or helium pressure of greater than about 0.01 Pascals in the chamber.

4. The radiation sensor of clause 2 or 3, wherein the gas supply mechanism is configured to maintain a hydrogen or helium pressure of less than about 100 Pascals in the chamber.

5. A radiation sensor comprising: a chamber for containing a gas, the chamber having a first opening and a second opening such that a radiation beam can enter the chamber through the first opening Propagating through the chamber and exiting the chamber through the second opening; a gas supply mechanism configured to maintain a gas in the chamber at a pressure greater than about 0.01 Pascal; a first electrode, Located in the chamber; a second electrode located in the chamber; a voltage source configured to maintain a potential difference between the first electrode and the second electrode; an inductive detector configured to measure flow through the first electrode and the second electrode a current of at least one of the currents resulting from ionization of the gas in the chamber caused by a radiation beam propagating through one of the chambers; and a processor operable to determine from the measured current Propagating through at least one of a power and a position of one of the radiation beams of the chamber.

6. The radiation sensor of clause 5, wherein the gas supply mechanism is configured to maintain a gas in the chamber at a pressure greater than about 0.1 Pascal.

7. The radiation sensor of clause 5 or 6, wherein the gas supply mechanism is configured to maintain a gas in the chamber at a pressure of less than about 100 Pascals.

8. The radiation sensor of any of clauses 5 to 7, wherein the gas supply mechanism is configured to maintain hydrogen or helium in the chamber.

The radiation sensor of any of the preceding clauses, further comprising a third electrode located in the chamber, wherein the voltage source is configured to be between the first electrode and the third electrode Maintaining a potential difference, and wherein the inductive detector is configured to measure a current flowing through one of the second electrodes and measure a current flowing through one of the third electrodes, wherein the first, second, and third electrodes Configuring one such that a position of the radiation beam propagating through one of the chambers in a first direction changes such that one of the current flowing through the second electrode changes and flows through the third electrode change.

10. The radiation sensor of clause 9, wherein the processor is operative to compare the current flowing through the second electrode with the current flowing through the third electrode and from the comparison to propagate through the chamber One of the radiation beams is in a position in the first direction.

11. The radiation sensor of clause 9 or 10, wherein the voltage source is configured to maintain the first electrode at a higher voltage than the second electrode and to maintain the third electrode compared to the third electrode A higher voltage.

12. The radiation sensor of any of clauses 9 to 11, wherein the voltage source is configured to maintain a potential difference between the first electrode and the second electrode and at the first electrode and the first A potential difference is maintained between the three electrodes, and the potential differences are substantially identical to each other.

The radiation sensor of any of the preceding clauses, further comprising a fourth electrode located in the chamber, wherein the voltage source is configured to be between the fourth electrode and the second electrode Maintaining a potential difference and configured to maintain a potential difference between the fourth electrode and the third electrode, wherein the first and fourth electrodes are configured such that a radiation beam propagates through one of the chambers at a first A change in position of one of the directions causes a change in one of the current flowing through the first electrode and a change in flow through the fourth electrode.

14. The radiation sensor of clause 13, wherein the inductive detector is configured to measure a current flowing through one of the first electrodes and a current flowing through the fourth electrode.

15. The radiation sensor of clause 14, wherein the processor is operative to compare the current flowing through the first electrode with the current flowing through the fourth electrode and from the comparison to propagate through the chamber One of the radiation beams is in a position in the first direction.

16. The radiation sensor of any of the preceding clause, further comprising: a fifth electrode located in the chamber; a sixth electrode located in the chamber; and a seventh electrode, Located in the chamber, wherein the voltage source is configured to maintain a potential difference between the fifth electrode and the sixth electrode and maintain a potential difference between the fifth electrode and the seventh electrode; wherein the inductance The detector is configured to measure a current flowing through one of the sixth electrodes and measure a current flowing through the seventh electrode; and wherein the fifth electrode, the sixth electrode, and the seventh electrode are configured such that A change in position of the radiation beam propagating through one of the chambers in a second direction causes one of the current flowing through the sixth electrode to change and one of the currents flowing through the seventh electrode to change.

17. The radiation sensor of clause 16, wherein the processor is operative to compare the current flowing through the sixth electrode with the current flowing through the seventh electrode and from the comparison to propagate through the chamber One of the radiation beams is in a position in the second direction.

18. The radiation sensor of clause 16 or 17, wherein the first and second directions extend perpendicular to the direction of propagation of the radiation beam through the chamber.

19. The radiation sensor of any of clauses 16 to 18, wherein the first and second directions extend perpendicular to each other.

The radiation sensor of any one of clauses 16 to 19, further comprising an eighth electrode located in the chamber, wherein the voltage source is configured to be at the eighth electrode and the sixth electrode Maintaining a potential difference therebetween and configured to maintain a potential difference between the eighth electrode and the seventh electrode, wherein the fifth and eighth electrodes are configured such that a radiation beam propagates through one of the chambers A change in position in the second direction causes one of the current flowing through the fifth electrode to change and one of the currents flowing through the eighth electrode to change.

21. The radiation sensor of clause 20, wherein the inductive detector is configured to measure a current flowing through one of the fifth electrodes and flowing through one of the eighth electrodes.

22. The radiation sensor of clause 21, wherein the processor is operative to compare the current flowing through the fifth electrode with the current flowing through the eighth electrode and from the comparison to propagate through the chamber One of the radiation beams is in a position in the second direction.

The radiation sensor of any of the preceding clauses, further comprising a beam splitter, the beam splitter configured to receive a radiation beam and split the radiation beam into a first portion and a second portion And guiding the second portion to propagate through the chamber.

24. The radiation sensor of clause 23, wherein the beam splitter comprises a grating.

25. A radiation sensor comprising: a chamber for containing a gas, the chamber having a first opening and a second opening such that a radiation beam can enter the chamber through the first opening Propagating through the chamber and exiting the chamber through the second opening; a gas supply mechanism configured to supply a gas into the chamber; a first electrode located in the chamber; a second electrode located in the chamber; a third electrode Located in the chamber; a voltage source configured to maintain a potential difference between the first electrode and the second electrode and maintain a potential difference between the first electrode and the third electrode; and an inductor a detector configured to measure a current flowing through one of the second electrodes and to flow a current of the third electrode, the current being caused in the chamber by a radiation beam propagating through one of the chambers Ionization of the gas; wherein the first, second, and third electrodes are configured such that a position of the radiation beam propagating through one of the chambers in a first direction changes to cause flow through the second electrode One of the current changes and one of the currents flowing through the third electrode changes; the radiation sensor further includes a processor operative to self-flow the measured current through the second electrode and flow through The measurement of the third electrode The flow is determined by the radiation beam propagating one of said one chamber in the direction of the first position.

26. The radiation sensor of clause 25, wherein the chamber is configured to receive a radiation beam substantially along a beam axis extending between the first opening and the second opening, and wherein the The second and third electrodes are configured such that one of the beam axis to one of the second and third electrodes projects for the first portion of the projection and coincides with the third electrode and for the second portion of the projection The second electrodes are coincident, and wherein the electrodes are configured such that a position of the beam axis in the first direction changes such that a length of the first portion of the projection is relative to a length of the second portion of the projection A change.

27. The radiation sensor of clause 26, wherein the second electrode comprises a first straight edge configured to intersect the projection of the beam axis to the second electrode, and wherein the third electrode comprises a A second straight edge is disposed to intersect the projection of the beam axis to the projection on the third electrode.

28. The radiation sensor of clause 27, wherein the first straight edge and the second straight edge are parallel to each other.

The radiation sensor of any one of clauses 25 to 28, wherein the processor is operative to compare the current flowing through the second electrode with the current flowing through the third electrode for comparison A position at which the radiation propagates through the one of the chambers in the first direction is determined.

The radiation sensor of any one of clauses 25 to 29, wherein the voltage source is configured to maintain the first electrode at a higher voltage than the second electrode and compared to the first The three electrodes are maintained at a higher voltage.

The radiation sensor of any one of clauses 25 to 30, wherein the processor is further operable to self-flow the measured current through the second electrode and the amount of flow through the third electrode At least one of the measured currents determines the power of one of the radiation beams propagating through one of the chambers.

The radiation sensor of any one of clauses 25 to 31, further comprising: a fifth electrode located in the chamber; a sixth electrode located in the chamber; and a seventh An electrode located in the chamber, wherein the voltage source is configured to maintain a potential difference between the fifth electrode and the sixth electrode and maintain a potential difference between the fifth electrode and the seventh electrode; The inductance detector is configured to measure a current flowing through one of the sixth electrodes and flow through a current of the seventh electrode; wherein the fifth electrode, the sixth electrode, and the seventh electrode are configured to cause propagation Changing a position of the radiation beam in one of the second directions through one of the chambers causes one of the current flowing through the sixth electrode to change and one of the currents flowing through the seventh electrode to change, and wherein the processor Operates to propagate from one of the measured currents flowing through the sixth electrode and the measured current flowing through the seventh electrode to propagate through one of the chambers The beam is in a position in the second direction.

33. The radiation sensor of clause 32, wherein the sixth and seventh electrodes are configured such that one of the beam axis to one of the sixth and seventh electrodes is projected for a first portion of the projection The sixth electrode coincides and coincides with the seventh electrode for a second portion of the projection, and wherein the sixth and seventh electrodes are configured such that a position of the beam axis changes in the second direction A change in the length of the first portion of the projection relative to the length of the second portion of the projection.

34. The radiation sensor of clause 32 or 33, wherein the processor is operative to compare the current flowing through the sixth electrode with the current flowing through the seventh electrode to propagate through the comparison determination One of the chambers radiates a position of the light beam in the second direction.

The radiation sensor of any one of clauses 32 to 34, wherein the first and second directions extend perpendicular to the direction of propagation of the radiation beam through the chamber.

The radiation sensor of any of clauses 32 to 35, wherein the first and second directions extend perpendicular to each other.

37. A radiation sensor system, comprising: a first radiation sensor according to any one of clauses 1 to 36, configured to determine a position of a radiation beam at a first location and a A second radiation sensor according to any one of clauses 1 to 36, configured to determine at least one of a position of the radiation beam at a second location and a power By.

38. The radiation sensor system of clause 37, wherein the first radiation sensor is configured to determine a position of the radiation beam at the first location, and the second radiation sensor is configured Determining a position of the radiation beam at the second location, and wherein the radiation sensor system further includes a processor configured to compare the determined position of the radiation beam at the first location with The radiation beam is at the determined position at the second location, and the radiation beam is determined by the comparison at the first radiation sensor and the second radiation sense A direction of propagation between the detectors.

The radiation sensor system of clause 37 or 38, wherein the first radiation sensor is configured to determine a position of the radiation beam at the first location, and the second radiation sensor is A configuration is made to determine the power of the radiation beam at the second location.

40. The radiation sensor system of clause 39, further comprising a beam splitter configured to receive the radiation beam between the first portion and the second portion, splitting the radiation beam Forming a first portion and a second portion and directing the second portion to the second portion.

41. A lithography system comprising: a radiation source configured to provide a primary radiation beam; a plurality of lithography devices; a beam delivery system configured to split the primary radiation beam into at least one And illuminating the radiation beam of any one of clauses 1 to 36 A sensor system, the radiation sensor or radiation sensor system configured to determine at least one of a power and a position of the primary radiation beam and/or a branch radiation beam.

42. The lithography system of clause 41, wherein the radiation source is configured to provide an EUV primary radiation beam.

43. The lithography system of clause 41 or 42, wherein the radiation source is configured to provide a pulsed primary radiation beam having a repetition rate greater than about 100 Hz.

The lithography system of any of clauses 41 to 43, wherein the source of radiation comprises at least one free electron laser.

45. A method of measuring at least one of a position of a radiation beam and a power, the method comprising: Providing a chamber for containing a gas, the chamber having a first opening and a second opening such that a radiation beam can enter the chamber through the first opening, propagate through the chamber, and pass the second An opening exits the chamber; supplying hydrogen or helium gas into the chamber; maintaining a potential difference between a first electrode located in the chamber and a second electrode located in the chamber; directing a radiation beam Propagating through the chamber; measuring a current flowing between at least one of the electrodes, the current resulting from hydrogen or helium in the chamber caused by the radiation beam propagating through the chamber Ionization; and determining, from the measured current, at least one of a power and a position of a radiation beam propagating through one of the chambers.

46. The method of clause 45, further comprising maintaining the hydrogen or helium gas in the chamber at a desired pressure.

47. The method of clause 46, wherein the hydrogen or helium gas is maintained at a pressure greater than about 0.01 Pascal.

The method of clause 46 or 47, wherein the hydrogen or helium gas is maintained at a pressure of less than about 100 Pascals.

49. A method of measuring at least one of a position of a radiation beam and a power, the method comprising: providing a chamber for containing a gas, the chamber having a first opening and a second opening Having a radiation beam entering the chamber through the first opening, propagating through the chamber and exiting the chamber through the second opening; supplying a gas into the chamber and maintaining the gas at greater than about 0.01 a pressure of Pascal; a first electrode located in the chamber and a second electrode located in the chamber Maintaining a potential difference; directing a radiation beam to propagate through the chamber; measuring flow through a current of at least one of the electrodes, the current resulting from the cavity caused by the radiation beam propagating through the chamber Ionization of the gas in the chamber; and determining, from the measured current, at least one of a power and a position of a radiation beam propagating through one of the chambers.

50. The method of clause 49, wherein the gas is maintained at a pressure greater than about 100 Pascals.

101‧‧‧radiation sensor

102‧‧‧radiation beam

105‧‧‧beam catheter

107a‧‧‧first aperture plate

107b‧‧‧Second aperture plate

108a‧‧‧first opening

108b‧‧‧second opening

110‧‧‧ chamber

112‧‧‧ gas supply parts

114‧‧‧ valve

116‧‧‧ pump

118‧‧‧pressure sensor

121‧‧‧First electrode

122‧‧‧second electrode

123‧‧‧ third electrode

125‧‧‧Electronics

131‧‧‧First electrical connector

132‧‧‧Second electrical connector

133‧‧‧ Third electrical connector

Claims (26)

A radiation sensor comprising: a chamber for containing a gas, the chamber having a first opening and a second opening, such that a radiation beam can enter the chamber through the first opening, and propagate Passing through the chamber and exiting the chamber through the second opening; a gas supply mechanism configured to supply hydrogen or helium gas into the chamber; a first electrode located in the chamber; a second electrode, located in the chamber; a voltage source configured to maintain a potential difference between the first electrode and the second electrode; an inductive detector configured to measure flow through Current of at least one of the first electrode and the second electrode, the current being caused by ionization of the hydrogen or helium in the chamber caused by a radiation beam propagating through one of the chambers; and A processor operative to determine at least one of a power and a position of one of the radiation beams propagating through the chamber from the measured current. The radiation sensor of claim 1, wherein the gas supply mechanism is configured to maintain a desired hydrogen or helium pressure in the chamber. The radiation sensor of claim 2, wherein the gas supply mechanism is configured to maintain a hydrogen or helium pressure of greater than about 0.01 Pascals in the chamber. The radiation sensor of claim 2 or 3, wherein the gas supply mechanism is configured to maintain a hydrogen or helium pressure of less than about 100 Pascals in the chamber. A radiation sensor comprising: a chamber for containing a gas, the chamber having a first opening and a second opening, such that a radiation beam can enter the chamber through the first opening, and propagate Passing through the chamber and exiting the chamber through the second opening; a gas supply mechanism configured to maintain a gas in the chamber at a pressure greater than about 0.01 Pascal; a first electrode located at a second electrode located in the chamber; a voltage source configured to maintain a potential difference between the first electrode and the second electrode; an inductive detector State measuring a current flowing through at least one of the first electrode and the second electrode, the current resulting from ionization of the gas in the chamber caused by a radiation beam propagating through one of the chambers And a processor operative to determine at least one of a power and a position of one of the radiation beams propagating through the chamber from the measured current. The radiation sensor of claim 5, wherein the gas supply mechanism is configured to maintain a gas in the chamber at a pressure greater than about 0.1 Pascal. The radiation sensor of claim 5 or 6, wherein the gas supply mechanism is configured to maintain a gas in the chamber at a pressure of less than about 100 Pascals. The radiation sensor of claim 5 or 6, wherein the gas supply mechanism is configured to maintain hydrogen or helium in the chamber. A radiation sensor comprising: a chamber for containing a gas, the chamber having a first opening and a second opening, such that a radiation beam can enter the chamber through the first opening, and propagate Passing through the chamber and exiting the chamber through the second opening; a gas supply mechanism configured to supply a gas into the chamber; a first electrode located in the chamber; a second An electrode located in the chamber; a third electrode located in the chamber; a voltage source configured to maintain a potential difference between the first electrode and the second electrode and maintain a potential difference between the first electrode and the third electrode; and an inductive detector State measuring a current flowing through one of the second electrodes and flowing a current of the third electrode, the current being caused by ionization of the gas in the chamber caused by a radiation beam propagating through one of the chambers Wherein the first, second and third electrodes are configured such that a position of the radiation beam propagating through one of the chambers in a first direction changes such that one of the currents flowing through the second electrode changes Reversing one of the currents flowing through the third electrode; the radiation sensor further comprising a processor operative to self-flow the measured current through the second electrode and to flow through the third electrode The measured current is determined to propagate through one of the chambers at a position in the first direction of the radiation beam. The radiation sensor of claim 9, wherein the chamber is configured to receive a radiation beam substantially along a beam axis extending between the first opening and the second opening, and wherein the second The third electrode is configured such that one of the beam axis to one of the second and third electrodes projects for the first portion of the projection and coincides with the third electrode and for the second portion of the projection The two electrodes are coincident, and wherein the electrodes are configured such that a change in position of the beam axis in the first direction causes a change in the length of the first portion of the projection relative to the length of the second portion of the projection . The radiation sensor of claim 10, wherein the second electrode comprises a first straight edge configured to intersect the projection of the beam axis to the second electrode, and wherein the third electrode comprises a configured a second straight edge intersecting the beam axis to the projection on the third electrode. The radiation sensor of claim 11, wherein the first straight edge and the second straight edge The edges are parallel to each other. The radiation sensor of any one of claims 9 to 12, wherein the processor is operative to compare the current flowing through the second electrode with the current flowing through the third electrode to determine propagation from the comparison The position of the beam in the first direction is radiated by one of the chambers. The radiation sensor of any one of claims 9 to 12, wherein the voltage source is configured to maintain the first electrode at a higher voltage than the second electrode and compared to the third electrode Maintain at a higher voltage. The radiation sensor of any one of claims 9 to 12, wherein the processor is further operable to self-flow the measured current through the second electrode and the measured current flowing through the third electrode At least one of the ones determines the power of one of the radiation beams propagating through one of the chambers. A radiation sensor system, comprising: a first radiation sensor according to any one of claims 1 to 15, configured to determine a position of a radiation beam at a first location and a power At least one of the second radiation sensors of any one of claims 1 to 15 configured to determine at least one of a position of the radiation beam at a second location and a power. The radiation sensor system of claim 16, wherein the first radiation sensor is configured to determine a position of the radiation beam at the first location, and the second radiation sensor is configured to determine The radiation beam is at a location at the second location, and wherein the radiation sensor system further includes a processor configured to compare the determined position of the radiation beam at the first location with the radiation The light beam is at the determined position at the second location, and a direction of propagation of the radiation beam between the first radiation sensor and the second radiation sensor is determined from the comparison. The radiation sensor system of claim 16 or 17, wherein the first radiation sensor is configured to determine a position of the radiation beam at the first location, and the second radiation sensor is configured To determine the power of the radiation beam at the second location. The radiation sensor system of claim 18, further comprising a beam splitter configured to receive the radiation beam between the first portion and the second portion, splitting the radiation beam into a first a portion and a second portion and guiding the second portion to the second portion. A lithography system comprising: a radiation source configured to provide a primary radiation beam; a plurality of lithography devices; a beam delivery system configured to split the primary radiation beam into at least one branch radiation And a radiation sensor of any one of claims 1 to 15 or a radiation sensing according to any one of claims 16 to 19; The radiation sensor or radiation sensor system is configured to determine at least one of a power and a position of the primary radiation beam and/or a branch radiation beam. A method of measuring at least one of a position of a radiation beam and a power, the method comprising: providing a chamber for containing a gas, the chamber having a first opening and a second opening such that a radiation beam can enter the chamber through the first opening, propagate through the chamber and exit the chamber through the second opening; supply hydrogen or helium gas into the chamber; in one of the chambers Maintaining a potential difference between the first electrode and one of the second electrodes in the chamber; directing a radiation beam to propagate through the chamber; Measure a current flowing between at least one of the electrodes, the current being caused by ionization of hydrogen or helium in the chamber caused by the radiation beam propagating through the chamber; The measured current is determined to propagate through at least one of a power and a position of one of the radiation beams of the chamber. The method of claim 21, further comprising maintaining the hydrogen or helium in the chamber at a desired pressure. The method of claim 22, wherein the hydrogen or helium gas is maintained at a pressure greater than about 0.01 Pascal. The method of claim 22 or 23, wherein the hydrogen or helium gas is maintained at a pressure of less than about 100 Pascals. A method of measuring at least one of a position of a radiation beam and a power, the method comprising: providing a chamber for containing a gas, the chamber having a first opening and a second opening such that a radiation beam can enter the chamber through the first opening, propagate through the chamber and exit the chamber through the second opening; supply a gas into the chamber and maintain the gas at greater than about 0.01 Pascals a pressure; maintaining a potential difference between a first electrode located in the chamber and a second electrode located in the chamber; directing a radiation beam to propagate through the chamber; measuring flow through the electrodes a current of at least one of the currents resulting from ionization of the gas in the chamber caused by the radiation beam propagating through the chamber; and determining from the measured current to propagate through the chamber At least one of a power and a position of the radiation beam. The method of claim 25, wherein the gas is maintained at a pressure greater than about 100 Pascals.