TW202117471A - Laser module as alignment source, metrology system, and lithographic apparatus - Google Patents

Abstract

An improved light laser module is disclosed. The laser module can include a laser source configured to generate laser light, and an infinite impulse response filter configured to reduce coherence effect of the laser light by decorrelating phase of components of the laser light. The infinite impulse response filter can include a plurality of optic couplers to form a plurality of optical propagation loops with different optical path length respectively. The laser module can further include an acoustic-optic modulator arranged in an optical propagation loop, and configured to shift optical carrier frequency, such that an output of the laser module has a widen spectral to further reduce coherence effect.

Description

Laser module, metrology system, and lithography device as an alignment source

The present invention relates to a laser module used as an alignment source in a metrology system that can be used, for example, in a lithography device.

The lithography device is a machine that applies the desired pattern to the target portion of the substrate. The lithography device can be used, for example, in the manufacture of integrated circuits (IC). In that case, a patterned device (which is alternatively called a mask or a reduction mask) can be used to generate a circuit pattern corresponding to the individual layers of the IC, and this pattern can be imaged to a radiation-sensitive material (resist ) Layer on a target portion (eg, a portion containing a die, a die, or a plurality of die) on a substrate (e.g., a silicon wafer). Generally speaking, a single substrate will contain a network of adjacent target portions that are sequentially exposed. Known photolithography devices include: so-called steppers, in which each target part is irradiated by exposing the entire pattern onto the target part at one time; and so-called scanners, in which by moving in a given direction ("scanning ”Direction) through the beam scanning pattern to simultaneously scan the substrate parallel or anti-parallel to this direction to irradiate each target part. It is also possible to transfer the pattern from the patterned device to the substrate by embossing the pattern onto the substrate. Another lithography system is an interference lithography system. In the interference lithography system, there is no patterned device. Instead, the beam is split into two beams, and the two beams are placed on the target part of the substrate by using a reflection system. Intervene at any time. This interference causes a line to be formed at the target portion of the substrate.

In order to control the lithography process to accurately place the device features on the substrate, alignment marks are usually set on the substrate, and the lithography device includes one or more alignment sensors. The sensor can measure the position of the alignment mark on the substrate with higher accuracy. These alignment sensors are located in the metrology system and are used to detect the positions of alignment marks (for example, X and Y positions) to align the substrate with the alignment marks to ensure accurate exposure of the light beam patterned by the mask . The metrology system can be used to determine the height of the wafer surface in the Z direction.

The alignment system usually includes a lighting system. The signal detected from the illuminated alignment mark may depend on the degree of matching between the wavelength of the illumination system and the physical or optical characteristics of the alignment mark or the physical or optical characteristics of the material contacting or adjacent to the alignment mark. The aforementioned characteristics may vary depending on the processing steps used. The alignment system can provide a narrowband radiation beam with a set of discrete, relatively narrow passbands in order to maximize the quality and intensity of the alignment mark signal detected by the alignment system.

Generally, the alignment sensor can detect more than one color produced by one or more laser sources. Generally, these lasers are centered at approximately 532 nm, 633 nm, 780 nm, and 850 nm. However, the existing green laser modules used to generate a wavelength of about 532 nm tend to have low durability and are highly coherent, which leads to the uncertainty of the alignment position due to the wafer-induced coherence effect (WICO) . The modal jump of the conventional green laser source can also cause alignment problems.

Therefore, there is a need for a new laser module as an alignment source in a metrology system to not only achieve a better working life but also reduce the coherence effect.

One aspect of the present invention provides a laser module, which includes: a laser source configured to generate laser light; and an infinite pulse response filter configured to be a component of the laser light The phase of the laser beam is decorrelated to reduce the coherence effect of the laser light.

In some embodiments, the laser source is configured to generate green laser light.

In some embodiments, the infinite pulse response filter includes a plurality of optical couplers to form a plurality of optical propagation loops with different optical path lengths.

In some embodiments, the plurality of optical propagation loops includes: a first optical propagation loop having a first optical fiber having a first optical fiber length; a second optical propagation loop having a first optical fiber length A second fiber of two fiber lengths; and a third optical propagation loop having a third fiber having a third fiber length; wherein the first fiber length, the second fiber length, and the third fiber length Greater than one of the coherent lengths of the laser light.

In some embodiments, an absolute value of a difference between the first optical fiber length and the second optical fiber length is greater than the coherent length of the laser light.

In some embodiments, an absolute value of a difference between the third optical fiber length and the sum of the first optical fiber length and the second optical fiber length is greater than the coherent length of the laser light.

In some embodiments, a sum of any integer multiples of any two of the three fiber lengths is not an integer multiple of the other of the three fiber lengths.

In some embodiments, a combination of the first fiber length, the second fiber length, and the third fiber length is one of the following: the first fiber length is 1.17 m, and the second fiber length is 2.63 m , And the length of the third fiber is 4.47 m; the length of the first fiber is 1.31 m, the length of the second fiber is 2.57 m, and the length of the third fiber is 4.49 m; the length of the first fiber is 1.67 m, and the length of the first fiber is 1.67 m. The length of the second optical fiber is 2.77 m, and the length of the third optical fiber is 4.57 m; or the length of the first optical fiber is 1.79 m, the length of the second optical fiber is 3.73 m, and the length of the third optical fiber is 5.93 m.

In some embodiments, the laser module further includes an acousto-optic modulator configured in an optical propagation loop and configured to shift an optical carrier frequency so that the One output of the laser module has a broadened spectrum to further reduce the coherence effect.

In some embodiments, the laser module further includes an optical fiber phase modulator, the optical fiber phase modulator is driven by a random phase signal to be a difference between the different spectral components of the output of the laser module The phase relationship is scrambled.

In some embodiments, the laser module further includes a variable optical attenuator configured as an optical switch.

In some embodiments, the plurality of optical couplers include: a first optical coupler including a first input port connected to the laser source; a second optical coupler including a first input port connected to the laser source; A first input port of a first output port of an optical coupler; a third optical coupler including a first input port connected to a second output port of the first optical coupler and a first input port connected to the first optical coupler A second output port and a second input port of two optical couplers; and a fourth optical coupler, which includes a first input port connected to a first output port of the third optical coupler, connected to A second input port of a second output port of the third optical coupler, a first output port connected to a second input port of the first optical coupler, and one of the second optical coupler A second output port of the second input port.

In some embodiments, the first optical fiber is disposed between the first output port of the third optical coupler and the first input port of the fourth optical coupler; and the second optical fiber is disposed on the third optical coupler. Between the second output port of the optical coupler and the second input port of the fourth optical coupler.

In some embodiments, the first optical fiber is disposed between the second output port of the first optical coupler and the first input port of the third optical coupler; and the second optical fiber is disposed on the second Between the second output port of the optical coupler and the second input port of the third optical coupler.

In some embodiments, the third optical fiber is disposed between the second output port of the fourth optical coupler and the second input port of the first optical coupler; or the third optical fiber is disposed on the fourth optical coupler. Between the first output port of the optical coupler and the second input port of the second optical coupler.

In some embodiments, the laser module further includes: the first optical coupler has a splitting ratio of 10:90; and the second optical coupler, the third optical coupler, and the fourth optics each have a splitting ratio of 50:50 .

In some embodiments, the laser module further includes: a first acousto-optic modulator disposed between the second output port of the first optical coupler and the first input port of the third optical coupler; and Two acousto-optic modulators are arranged between the second output port of the second optical coupler and the second input port of the third optical coupler.

In some embodiments, the laser module further includes: a first acousto-optic modulator disposed between the first output port of the third optical coupler and the first input port of the fourth optical coupler; and Two acousto-optic modulators are arranged between the second output port of the third optical coupler and the second input port of the fourth optical coupler.

Another aspect of the present invention provides a metrology system including a multi-color radiation source that includes the disclosed laser module and is configured to generate alignment light.

Another aspect of the present invention provides a lithography device including the disclosed metrology system.

The other features and advantages of the present invention and the structure and operation of various embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Based on the teachings contained herein, additional embodiments will be obvious to those familiar with the related art.

This specification discloses one or more embodiments incorporating the features of the present invention. The disclosed embodiments merely exemplify the invention. The scope of the present invention is not limited to the disclosed embodiments. The present invention is defined by the scope of the patent application attached herewith.

The described embodiments and the references in this specification to "one embodiment," "an embodiment," "example embodiment," etc. indicate that the described embodiment may include specific features, structures, or characteristics, but each embodiment may not necessarily include The specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. In addition, when describing a particular feature, structure or characteristic in combination with the embodiment, it should be understood that whether it is explicitly described or not, the combination of other embodiments to realize this feature, structure or characteristic is within the knowledge range of those who are familiar with the art. .

However, before describing such embodiments in more detail, it is instructive to present an example environment in which embodiments of the present invention can be implemented.

Example reflection and transmission lithography system

FIG. 1A and FIG. 1B are respectively schematic illustrations of a lithography device 100 and a lithography device 100' that can implement embodiments of the present invention. The lithography device 100 and the lithography device 100' each include the following: an illumination system (illuminator) IL, which is configured to adjust the radiation beam B (for example, deep ultraviolet or extreme ultraviolet radiation); a support structure (for example, a shield Mask stage) MT, which is configured to support a patterned device (for example, a mask, a reduction mask, or a dynamic patterned device) MA and is connected to a first positioner configured to accurately position the patterned device MA PM; and the substrate table (eg, wafer table) WT, which is configured to hold the substrate (eg, resist coated wafer) W and is connected to a second positioner configured to accurately position the substrate W PW. The lithography devices 100 and 100' also have a projection system PS configured to project the pattern imparted by the patterning device MA to the radiation beam B onto a target portion of the substrate W (for example, including one or more die ) C on. In the lithography apparatus 100, the patterning device MA and the projection system PS are reflective. In the lithography apparatus 100', the patterning device MA and the projection system PS are transmissive.

The illumination system IL may include various types of optical components for guiding, shaping or controlling the radiation beam B, such as refraction, reflection, catadioptric, magnetic, electromagnetic, electrostatic or other types of optical components or any combination thereof.

The support structure MT depends on the orientation of the patterned device MA relative to the reference frame RF, the design of at least one of the lithography apparatus 100 and 100', and other conditions (such as whether the patterned device MA is held in a vacuum environment) Way to hold the patterned device MA. The support structure MT may use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterned device MA. The support structure MT may be a frame or a table, for example, it may be fixed or movable as required. By using the sensor, the support structure MT can ensure that the patterned device MA is in a desired position relative to the projection system PS, for example.

The term "patterned device" MA should be broadly interpreted as referring to any device that can be used to impart a patterned radiation beam B in its cross-section so as to create a pattern in the target portion C of the substrate W. The pattern imparted to the radiation beam B may correspond to a specific functional layer in the device that is generated in the target portion C to form an integrated circuit.

The patterned device MA may be transmissive (as in the lithography device 100' of FIG. 1B) or reflective (as in the lithography device 100 of FIG. 1A). Examples of the patterned device MA include zoom masks, masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase shift, and attenuated phase shift, and various hybrid mask types. An example of a programmable mirror array uses a matrix configuration of small mirrors, each of which can be individually tilted to reflect the incident radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam B reflected by the matrix of small mirrors.

The term "projection system" PS may cover any type of projection system suitable for the exposure radiation used or suitable for other factors such as the use of immersion liquid on the substrate W or the use of vacuum, including refraction, reflection, catadioptric, Magnetic, electromagnetic and electrostatic optical systems or any combination thereof. The vacuum environment can be used for EUV or electron beam radiation, because other gases can absorb too much radiation or electrons. Therefore, the vacuum environment can be provided to the entire beam path by virtue of the vacuum wall and the vacuum pump. Any use of the term "projection lens" herein can be considered as synonymous with the more general term "projection system".

As depicted here, the device is of the transmissive type (for example, with a transmissive mask). Alternatively, the device may be of the reflective type (for example, using a programmable mirror array of the type mentioned above or using a reflective mask).

The lithography device 100 and/or the lithography device 100' may belong to a type having two (dual stage) or more substrate tables WT (and/or two or more mask tables). In such a "multi-stage" machine, additional substrate tables WT can be used in parallel, or preliminary steps can be performed on one or more tables while one or more other substrate tables WT are used for exposure. In some cases, the additional table may not be the substrate table WT. The two substrate tables WTa and WTb in the example of FIG. 1B illustrate this situation. The present invention disclosed herein can be used in a standalone manner, but in detail, the present invention can provide additional functions in the pre-exposure measurement stage of either a single stage device or a multiple stage device.

The lithography device may also belong to the following type: at least a part of the substrate can be covered by a liquid (for example, water) having a relatively high refractive index, so as to fill the space between the projection system and the substrate. The immersion liquid can also be applied to other spaces in the lithography device, for example, the space between the mask and the projection system. The immersion technique is well known in the art for increasing the numerical aperture of the projection system. The term "wetting" as used herein does not mean that a structure such as a substrate must be submerged in liquid, but only means that the liquid is located between the projection system and the substrate during exposure.

1A and 1B, the illuminator IL receives the radiation beam from the radiation source SO. For example, when the source SO is an excimer laser, the source SO and the lithography device 100, 100' may be separate physical entities. In such cases, the source SO is not considered to form part of the lithography device 100 or 100', and the radiation beam B relies on a beam delivery system BD including, for example, a suitable guiding mirror and/or a beam expander (in FIG. 1B ) And passed from the source SO to the luminaire IL. In other cases, for example, when the source SO is a mercury lamp, the source SO may be an integral part of the lithography device 100, 100'. The source SO and the illuminator IL together with the beam delivery system BD (if necessary) can be referred to as a radiation system.

The illuminator IL may include an adjuster AD (in FIG. 1B) for adjusting the angular intensity distribution of the radiation beam. Generally, at least the outer and/or inner radial extent of the intensity distribution in the pupil plane of the illuminator can be adjusted (usually referred to as "σouter" and "σinner", respectively). In addition, the illuminator IL may include various other components (in FIG. 1B), such as an accumulator IN and a condenser CO. The illuminator IL can be used to adjust the radiation beam B to have a desired uniformity and intensity distribution in its cross section.

1A, the radiation beam B is incident on a patterning device (for example, a mask) MA held on a support structure (for example, a mask table) MT, and is patterned by the patterning device MA. In the lithography apparatus 100, the radiation beam B is reflected from the patterned device (eg, mask) MA. After being reflected from the patterned device (eg, mask) MA, the radiation beam B passes through the projection system PS, which focuses the radiation beam B onto the target portion C of the substrate W. By virtue of the second positioner PW and the position sensor IF2 (for example, an interference device, a linear encoder or a capacitive sensor), the substrate table WT can be accurately moved (for example, to position different target parts C on the radiation beam B In the path). Similarly, the first positioner PM and the other position sensor IF1 can be used to accurately position the patterned device (eg, mask) MA relative to the path of the radiation beam B. The mask alignment marks M1, M2 and the substrate alignment marks P1, P2 can be used to align the patterned device (for example, the mask) MA and the substrate W.

1B, the radiation beam B is incident on a patterning device (for example, a mask MA) held on a supporting structure (for example, a mask table MT), and is patterned by the patterning device. Having traversed the mask MA, the radiation beam B passes through the projection system PS, which focuses the beam onto the target portion C of the substrate W. By virtue of the second positioner PW and the position sensor IF (for example, an interferometric device, a linear encoder or a capacitive sensor), the substrate table WTa/WTb can be accurately moved (for example, to position the different target parts C on the radiation In the path of beam B). Similarly, the first positioner PM and another position sensor (not shown in FIG. 1B) can be used to accurately position the mask MA relative to the path of the radiation beam B (for example, mechanically in the self-mask library After acquisition or during scanning).

Generally speaking, the movement of the mask table MT can be realized by the long-stroke module (coarse positioning) and the short-stroke module (fine positioning) forming part of the first positioner PM. Similarly, the long-stroke module and the short-stroke module forming part of the second positioner PW can be used to realize the movement of the substrate table WTa/WTb. In the case of a stepper (as opposed to a scanner), the mask stage MT may be connected to a short-stroke actuator only, or may be fixed. The mask alignment marks M1 and M2 and the substrate alignment marks P1 and P2 can be used to align the mask MA and the substrate W. Although the substrate alignment marks (as illustrated) occupy dedicated target portions, the substrate alignment marks may be located in the spaces between the target portions (such substrate alignment marks are referred to as scribe lane alignment marks). Similarly, when more than one die is provided on the mask MA, the mask alignment mark can be located between the die.

The lithography devices 100 and 100' can be used in at least one of the following modes:

1. In the stepping mode, when the entire pattern imparted to the radiation beam B is projected onto the target portion C at one time, the supporting structure (for example, the mask stage) MT and the substrate stage WTa/WTb basically remain stationary ( That is, a single static exposure). Then, the substrate tables WTa/WTb are shifted in the X and/or Y directions, so that different target portions C can be exposed. In the step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure.

2. In the scanning mode, when the pattern imparted to the radiation beam B is projected onto the target portion C, the support structure (for example, the mask stage) MT and the substrate stage WTa/WTb (that is, single dynamic exposure). The speed and direction of the substrate table WTa/WTb relative to the support structure (for example, the mask table) MT can be determined by the magnification (reduction ratio) and image reversal characteristics of the projection system PS. In the scanning mode, the maximum size of the exposure field limits the width of the target portion (in the non-scanning direction) in a single dynamic exposure, and the length of the scanning motion determines the height of the target portion (in the scanning direction).

3. In another mode, when the pattern imparted to the radiation beam B is projected onto the target portion C, the support structure (for example, the mask stage) MT remains substantially stationary, thereby holding the programmable patterned device, and Move or scan the substrate table WTa/WTb. In this mode, a pulsed radiation source SO is usually used, and the programmable patterned device is updated as necessary after each movement of the substrate table WTa/WTb or between successive radiation pulses during scanning. This mode of operation can be easily applied to unmasked lithography using programmable patterned devices (such as the type of programmable mirror array mentioned above).

Combinations and/or variations of the described usage modes or completely different usage modes can also be adopted.

The lithography apparatus LA belongs to the so-called dual stage type, which has two substrate tables WTa and WTb and two stations—an exposure station and a measuring station, between which the substrate tables can be exchanged. While one substrate on one substrate stage is being exposed at the exposure station, another substrate can be loaded onto another substrate stage at the measurement station, so that various preparatory steps can be performed. The preliminary step may include using the level sensor LS to map the surface of the substrate and using the alignment sensor AS to measure the position of the alignment marker on the substrate. This can substantially increase the output of the device. If the position sensor IF cannot measure the position of the substrate table when the substrate table is at the measuring station and at the exposure station, a second position sensor can be provided to enable tracking of the position of the substrate table at two stations .

The device further includes a lithography device control unit LACU, which controls all movements and measurements of the various actuators and sensors described. LACU also includes signal processing and data processing capabilities to perform required calculations related to the operation of the device. In practice, the control unit LACU will be implemented as a system of many sub-units, each of which handles real-time data acquisition, processing and control of the subsystems or components in the device. For example, a processing subsystem can be dedicated to the servo control of the substrate positioner PW. A single unit can even handle coarse and fine actuators or different axes. The other unit can be dedicated to the readout of the position sensor IF. The overall control of the device can be controlled by the central processing unit, which communicates with these subsystem processing units, communicates with the operator, and communicates with other devices involved in the lithography manufacturing process.

Example alignment sensor

FIG. 2 is a schematic block diagram of the alignment sensor AS. The illumination source 220 provides an alignment beam 222 of radiation of one of more wavelengths and/or polarizations, and the alignment beam 222 is turned to a mark (such as the mark 202) on the substrate W via the objective lens 224.

In some embodiments, the illumination source 220 may include a multi-color laser module assembly (LMA) configured to generate multiple laser beams centered on different wavelengths. For example, the multi-color LMA may include four separate laser sources to generate radiation having four wavelengths, such as a green laser centered at about 532 nm, a red laser centered at about 633 nm, and a laser centered at about 633 nm. Near-infrared (NIR) laser centered at 780 nm and far-infrared (FIR) laser centered at approximately 850 nm. In some embodiments, the multi-color LMA can further modulate the polarization of the multiple laser beams, and then combine the multiple laser beams into an alignment beam 222.

The radiation scattered by the marker 202 is picked up by the objective lens 224 and collimated into an information-carrying beam 226. The self-reference interferometer 228 is of the type disclosed in the aforementioned US Patent No. 6,961,116, and it processes the beam 226 and outputs a separate beam (for each wavelength) to the sensor array 230. The point mirror 223 suitably serves as a zero-order stop at this time, so that the information-carrying beam 226 only contains higher-order diffracted radiation from the mark 202 (this is not necessary for the measurement, but improves the signal-to-noise ratio). The intensity signal 232 from the individual sensor in the sensor grid 230 is provided to the processing unit PU. By combining the optical processing in the block 228 and the calculation processing in the unit PU, the values of the X and Y positions on the substrate relative to the sensor are output. The processing unit PU can be separated from the control unit LACU shown in FIG. 1, or for design choice and convenience, the processing unit PU and the control unit LACU can share the same processing hardware. In the case where the unit PU is separated, part of the signal processing can be performed in the unit PU, and another part of the signal processing can be performed in the unit LACU.

As already mentioned, the specific measurement described only fixes the position of the mark within a certain range corresponding to a pitch of the mark. In combination with this measurement, a rougher measurement technique is used to identify which period of the sine wave is the period containing the marked position. The same procedure at a rough and/or fine level can be repeated at different wavelengths to improve accuracy and to detect the mark steadily, regardless of the materials used to make the mark and leave the mark. The wavelengths can be multiplexed and demultiplexed optically so as to process the wavelengths at the same time and/or the wavelengths can be multiplexed by time sharing. The example in the present invention will use measurement at several wavelengths to provide a practical and stable measurement device (alignment sensor) with reduced sensitivity to mark asymmetry.

With reference to the measurement procedure in more detail, _{the arrow marked v W} in FIG. 2 illustrates the scanning speed of the light spot 206 across the length L of the mark 202. In this example, the alignment sensor AS and the light spot 206 actually remain stationary, while the substrate _W moves at a speed vW. Therefore, the alignment sensor can be rigidly and accurately mounted to the reference frame RF as shown in FIG. 1B while effectively scanning the mark 202 in the direction opposite to the moving direction of the substrate W. During this movement, the substrate is controlled because it is mounted on the substrate table WT and the substrate positioning system PW. All movements shown are parallel to the X axis. A similar action applies to scanning the mark 204 in the Y direction with the light spot 208. This will not be described further.

As discussed in U.S. Patent No. 8,593,464, the high-productivity output requirements of lithography devices require the measurement of alignment marks at several positions on the substrate as quickly as possible, which means that the scanning speed vW is faster. And the time TACQ that can be used to obtain each mark position is correspondingly shorter. In short, the formula TACQ = L/vW applies. U.S. Patent No. 8,593,464 describes a technique for imparting relative scanning motion of the light spot in order to extend the acquisition time. If necessary, the same scanning light spot technology can be applied to sensors and methods of the type newly disclosed in this article.

There is interest in alignment on marks with smaller grating pitches. The measured overlap in real production is usually significantly larger than the measured overlap under controlled test conditions. Studies have shown that this is caused by the alignment marks on the product wafer becoming asymmetric to varying degrees during processing. Reducing the distance between the alignment marks reduces the effect of some types of asymmetry on the measured alignment position.

Those skilled in the art know that some of the options that allow reducing the distance between the alignment gratings are (i) shorten the wavelength of the radiation used, (ii) increase the NA of the alignment sensor optics, and (iii) use off-axis illumination. Shorter wavelengths are not always possible because the alignment grating is usually located under the absorbing film (for example, an amorphous carbon hard mask). Increasing NA is usually possible but not preferable because it requires a compact objective lens with a safe distance from the wafer. Therefore, the use of off-axis lighting systems is attractive.

As an improved green laser module for targeting lasers

As described above, existing green laser modules (for example, with a wavelength centered at 532 nm) tend to have much lower durability than expected. For example, the green laser module currently used in the existing multi-color laser module assembly (LMA) of the alignment sensor AS uses a diode pumped solid state (DPSS) laser, which suffers less than six The problem of the low B10 service life of months and the low B20 service life of only about one year. Those familiar with this technology know that B10 service life is defined as the measurement of the time when 10% of the total product will fail, and B20 service life is defined as the time that 20% of the total product will fail. Measurement of time to failure.

In addition, the Wafer Induced Coherence Effect (WICO) for calibration and testing of each laser causes position uncertainty. The existing green laser modules are usually highly coherent sources, so the alignment position uncertainty is caused by WICO. In addition, the modal jump of the existing green laser module is usually also a contributing factor to the shift between order (SBO) jumps, and these jumps are highlighted by the green color when used for alignment. In addition, the laser beam switch (LBS) of the existing green laser module is also prone to malfunction and failure. Therefore, the present invention provides an improved green laser module to solve these and other problems.

In some embodiments, the disclosed green laser module can ensure that the photon packet emitted from the disclosed green laser module includes multiple copies of the green laser light at any time during measurement. The incident light is emitted before a number of "coherent time" intervals. In other words, the light output of the disclosed green laser module theoretically contains infinite copies of light delayed beyond the coherence length of the laser itself, thus destroying the coherence relationship in the photon beam.

In some embodiments of the present invention, the disclosed green laser module may include an infinite impulse response (IIR) filter constructed by using multiple optical couplers (also called "fiber splitters") and patch cords . In some embodiments, the light input of the IIR filter can be split into three loops _{with three different fiber lengths (ie, L 1} , L _2, and L _{3 ). By specifically selecting the values of the three fiber lengths L 1} , L ₂ and L ₃ that follow a certain rule as described below, the integer numbers of the three cycles of the signals from these fiber decorrelators cannot be in phase with each other. Relationship, thereby eliminating WICO.

3 to 8 illustrate schematic diagrams of a green laser module including an exemplary IIR filter according to various embodiments of the present disclosure.

Referring to FIG. 3, the green laser module G1 may include a green laser source 310. In some embodiments, the green laser source 310 may be any suitable laser source that emits continuous or pulsed laser radiation having a wavelength band centered at about 532 nm. In some embodiments, the green laser source 310 may have a mean time before failure (MTTF) greater than 400 KHr, which may produce a significantly better B10 service life. However, the green laser source 310 may have a coherent length (L _c ) of about 10 mm, and therefore may have worse WICO performance.

In order to obtain better WICO performance, the green laser source 310 may further include an infinite impulse response (IIR) filter to reduce the coherence effect. In some embodiments, the IIR filter may include multiple optical couplers (also referred to as "fiber splitters"), such as a first optical coupler 410, a second optical coupler 420, a third optical coupler 430, The fourth optical coupler 440 and the fifth optical coupler 450.

As shown in FIG. 3, the green light output from the green laser source 310 can be delivered to the first input port 410a of the first optical coupler 410. It should be noted that in FIGS. 3 to 8, each solid line with an arrow represents an optical fiber, and the arrow represents the propagation direction of light in the optical fiber. The first optical coupler 410 may have a light splitting ratio of 10:90. That is, the output light of the first output port 410c contains 10% power of the input light from the first input port 410a and 90% power of the input light from the second input port 410b, and the output light of the second output port 410d contains 90% power of the input light from the first input port 410a and 10% power of the input light from the second input port 410b. The output light from the first output port 410c of the first optical coupler 410 may be delivered to the first input port 420a of the second optical coupler 420. The output light from the second output port 410d of the first optical coupler 410 can be delivered to the first input port 430a of the third optical coupler 430.

In some embodiments, the optical fiber disposed between the two devices may be connected via a polarization maintaining (PM) connector 510. For example, the PM connector 510 can be used to connect the optical fiber disposed between the first output port 410c of the first optical coupler 410 and the first input port 420a of the second optical coupler 420, and the other PM connector 510 can be used for The optical fiber disposed between the second output port 410d of the first optical coupler 410 and the first input port 430a of the third optical coupler 430 is connected. It should be noted that a solid ellipse shape is used to illustrate the PM joint 510 in FIGS. 3 to 12. Those skilled in the art know that the PM connector 510 can be used to connect optical fibers to construct an optical waveguide between two optical devices. Therefore, the PM connector 510 will not be described below in conjunction with FIGS. 3 to 12.

In some embodiments, the second optical coupler 420 may be a 3 dB coupler and has a splitting ratio of 50:50. In other words, each of the output light of the first output port 420c and the second output port 420d contains 50% power of the input light from the first input port 420a and 50% power of the input light from the second input port 420b. The output light from the first output port 420c of the second optical coupler 420 can be delivered to the input port 450a of the fifth optical coupler 450 via a variable optical attenuator (VOA) 520. VOA 520 can be used as a light shield, but it is more reliable than the current laser beam switch (LBS) wheel. The output light from the second output port 420d of the second optical coupler 420 can be delivered to the second input port 430b of the third optical coupler 430.

In some embodiments, the fifth optical coupler 450 may have a splitting ratio of 99:1. The output light of the first output port 450c contains 99% of the power of the input light from the first input port 450a. The first output port 450c of the fifth optical coupler 450 is the main output terminal of the green laser module G1, and can be delivered to the Fibre Channel Protocol (FCP, not shown in FIG. 3). The output light from the second output port 450d of the fifth optical coupler 450 contains 1% of the power of the input light from the first input port 450a, and can be used for testing purposes, and can be delivered to the diagnostic output terminal (Figure 3 Not shown).

In some embodiments, the third optical coupler 430 may be a 3 dB coupler and has a splitting ratio of 50:50. In other words, each of the output light of the first output port 430c and the second output port 430d contains 50% power of the input light from the first input port 430a and 50% power of the input light from the second input port 430b. Shown in FIG. 3, the first output from the third port of the optical coupler 430 430c of the fourth output light can be delivered to a first input port of the optical coupler 440a 440 via the optical fiber having a first length L ₁ of the first. The output light from the second output port 430d of the third optical coupler 430 can be delivered to the second input port 440b of the fourth optical coupler 440 _{through a second optical fiber having a second length L 2.}

In some embodiments, the fourth optical coupler 440 may be a 3 dB coupler and has a splitting ratio of 50:50. In other words, each of the output light of the first output port 440c and the second output port 440d contains 50% power of the input light from the first input port 440a and 50% power of the input light from the second input port 440b. As shown in FIG. 3, the output light from the first output port 440c of the fourth optical coupler 440 may be delivered to the first input port 420a of the second optical coupler 420 to form a loop. The second output from the fourth port of the optical coupler 440 440d may be delivered via an output light having a third length L ₃ of the third optical fiber to the first optical coupler 410, a second input port 410b to form a loop.

Each of the three fiber lengths L ₁ , L ₂ and L ₃ is greater than the coherent length (L _c ) of the green laser. Certain rules can be followed to determine the values of the _{three fiber lengths L 1} , L ₂ and L _3. In some embodiments, the absolute value of the difference between the _{first fiber length L 1} and the second fiber length L _{2 is greater than the coherent length (L c} ) of the green laser. In addition, the absolute value of the difference between the third fiber length L ₃ and the sum of the first fiber length L ₁ and the second fiber length L _{2 is greater than the coherent length (L c} ) of the green laser. In addition, the sum of any integer multiples of any two of the three fiber lengths cannot be expressed as an integer multiple of the other of the three fiber lengths. That is, A ₁ L _x + A ₂ L _y ≠ A ₃ L _z , where A ₁ , A ₂ and A ₃ are any integer numbers greater than or equal to 1, and the set {x, y, z} = {1, twenty three}. By specifically selecting the values of the three fiber lengths L ₁ , L _2, and L ₃ in this way, the integer number of cycles of the signals from these fiber decorrelators cannot be in phase with each other. That is, multiple photon beams generated by multiple optical propagation cycles are tuned out of phase, thereby eliminating WICO.

Various combinations of the three fiber lengths L ₁ , L _2, and L ₃ can satisfy the above-described rule for determining the values of the _{three fiber lengths L 1} , L ₂ and L _3. For example, the first optical fiber length L ₁ may be equal to 1.17 m, the second optical fiber length L ₂ may be equal to 2.63 m, and the third optical fiber length L ₃ may be equal to 4.47 m. As another example, the first fiber length L ₁ may be equal to 1.31 m, the second fiber length L ₂ may be equal to 2.57 m, and the third fiber length L ₃ may be equal to 4.49 m. As yet another example, the first fiber length L ₁ may be equal to 1.67 m, the second fiber length L ₂ may be equal to 2.77 m, and the third fiber length L ₃ may be equal to 4.57 m. As yet another example, the first fiber length L ₁ may be equal to 1.79 m, the second fiber length L ₂ may be equal to 3.73 m, and the third fiber length L ₃ may be equal to 5.93 m. It should be noted that the three fiber lengths L ₁ , L ₂ and L ₃ are not limited by the combination disclosed above, but may have any other suitable values that satisfy the disclosed rules.

4 to 5, there are shown schematic diagrams of other exemplary green laser modules G11 and G12 according to some other embodiments of the present invention. It should be noted that the same components such as the green laser source 310, the optical couplers 410 to 450, the PM connector 510, etc., which have been described above in conjunction with FIG. 3, are not repeated herein.

Compare the green laser module G11 shown in Figure 4 with the green laser module G1 shown in Figure 3, using an acousto-optic modulator (AOM) in the IIR filter to pass through each time The optical carrier frequency is systematically moved up or down by 200 MHz. As shown in FIG. 4, the first AOM 530-1 can be connected between the second output port 410d of the first coupler 410 and the first input port 430a of the third optical coupler 430. The first AOM 530-1 may be driven by a first radio frequency (RF) driver 540-1. The second AOM 530-2 can be connected between the second output port 420d of the second coupler 410 and the second input port 430b of the third optical coupler 430. The second AOM 530-2 may be driven by a second radio frequency (RF) driver 540-2. Two AOMs can also blue-shift the carrier frequency, thus broadening the spectral output of the green laser, which makes it possible to reduce the alignment position uncertainty of the WICO effect.

9, there is shown a schematic diagram of the spectral broadening of the output green laser after one or more cycles according to some embodiments of the present invention. As shown in the figure on the left, the initial green laser at a wavelength of 532 nm has its power centered at a fixed λ/f, where λ is the nominal center wavelength of the laser 310 (for example, 532 nm), and f is The RF frequency applied to the two AOM 530-1 and 530-2. In some embodiments, two AOMs can shift the optical carrier frequency positively and negatively by 200 MHz after one loop, as shown in the middle diagram of FIG. 9. That is, the output of the up-converted AOM can be at a frequency corresponding to (532 nm + 200 MHz), and the output of the down-converted AOM can be at a frequency corresponding to (532 nm-200 MHz). Therefore, the power can be separated by plus and minus 200 MHz in the spectrum. After a large number of loops, two AOMs can repeatedly shift the green laser frequency positively and negatively by 200 MHz. That is, the spectral components can be widely distributed at multiple values of wavelength/frequency separated by 200 MHz. Therefore, the output green laser at any time can have a large number of copies of the green light emitted by the green laser source 310 and multiple positive or negative 200 MHz frequency shifted spectral components. Therefore, the coherent phase relationship existing in the photon beam can be broken at any time, thereby reducing the WICO effect.

It should be noted that the AOM can be arranged at different positions of the optical circuit of the IIR filter. For example, in the green laser module G12 as shown in FIG. 5, the first AOM 530-1 driven by the first radio frequency (RF) driver 540-1 can be connected to the first AOM 530-1 of the third coupler 430 Between the output port 410d and the first input port 440a of the fourth optical coupler 440, the second AOM 530-2 driven by the second radio frequency (RF) driver 540-2 can be connected to the second Between the output port 430d and the second input port 440b of the fourth optical coupler 430.

In some embodiments, the optical fiber phase modulator 550 may be connected behind the first output port 450c of the fifth optical coupler 450. The fiber phase modulator 550 can be driven by a random phase sinusoidal signal to further scramble the phase relationship between the different spectral components of the output of the green laser, thereby further reducing the alignment position uncertainty of the WICO effect.

6-8, there are shown schematic diagrams of other exemplary green laser modules G2, G3, and G4 according to some other embodiments of the present invention. It should be noted that the same components such as the green laser source 310, the optical couplers 410 to 450, the PM connector 510, etc., which have been described above in conjunction with FIG. 3, are not repeated herein. In some embodiments, _{the positions of the three optical fibers with different lengths L 1} , L ₂ and L ₃ can be arranged at different positions of the optical circuit of the IIR filter.

In some embodiments, comparing the green laser module in FIG. 6 shows in the G2 and G1 green laser module shown in FIG. 3, the first optical fiber having a length L ₁ of the first optical fiber may be disposed in the first Between the second output port 410d of an optical coupler 410 and the first input port 430a of the third optical coupler 430, the second optical fiber having the second optical fiber length L ₂ can be arranged on the first optical coupler 420 Between the second output port 420d and the second input port 430b of the third optical coupler 430. It should be noted that although not shown in the figures, as described above in conjunction with FIG. 4 and FIG. 5, two AOMs can be added at different positions in the IIR filter of the green laser module G2.

In some other embodiments, comparing the green laser module G3 as shown in FIG. 7 with the green laser module G1 as shown in FIG. 3, the third optical fiber with the third optical fiber length L ₃ can be configured in Between the first output port 440c of the fourth optical coupler 440 and the first input port 420a of the second optical coupler 430. Similarly, although not shown in the figures, as described above in conjunction with FIG. 4 and FIG. 5, two AOMs can be added at different positions in the IIR filter of the green laser module G3.

In some other embodiments, comparing the green laser module G4 as shown in FIG. 8 with the green laser module G1 as shown in FIG. 3, the first optical fiber having the first optical fiber length L ₁ can be configured in Between the second output port 410d of the first optical coupler 410 and the first input port 430a of the third optical coupler 430, a second optical fiber having a second optical fiber length L ₂ can be arranged on the second optical coupler 420 Between the second output port 420d and the second input port 430b of the third optical coupler 430, and the third optical fiber having the third optical fiber length L ₃ can be arranged in the first output port 440c and the second Between the first input ports 420a of the optical coupler 430. Similarly, although not shown in the figures, as described above in conjunction with FIG. 4 and FIG. 5, two AOMs can be added at different positions in the IIR filter of the green laser module G4.

It should be understood that the present invention has been made only with the help of examples, and several changes can be made to the details of the embodiments of the present invention without departing from the spirit and scope of the present invention. The features of the disclosed embodiments can be combined and reconfigured in various ways. Without departing from the spirit and scope of the present invention, the modifications, equivalents or improvements of the present invention are understandable to those skilled in the art, and such modifications, equivalents or improvements are intended to be covered by Within the scope of the present invention. For example, the split ratios of the five optical couplers 410 to 450 described above are only exemplary and should not be limited. For example, there are other splitting ratios such as 95:5, 90:10, 80:20, 75:25, 60:40, 40:60, 25:75, 20:80, 10:90, 5:95, etc. Any suitable optical coupler can be used in the IIR filter of the disclosed green laser module. As another example, the number of optical couplers is also not limited herein. In some embodiments not shown in the figures, an optical coupler array with M columns and N rows of optical couplers can be connected to construct an IIR filter.

Therefore, the present invention provides an improved green laser module to obtain better working life, reduced coherence effect and faster switching speed. By using the disclosed IIR filter to decorrelate the phase of the green laser and by using AOMS to add spectral components, when light is emitted from the output end of the green laser module, the disclosed green laser module can avoid The photon beams below the spectral envelope have the same phase relationship. Different green components can occupy the same spectral range, but at any time, all photons are configured to be out of phase between the wave packets (for example, the photons do not have the same phase relationship), because when traveling in the same length After (L _c ) or when combining light with a duration longer than the coherence time (T _c ), the phase relationship between different photons is destroyed. Therefore, the generated green light undergoes a large amount of reflection in the integrating sphere, and the combined light may lose coherence after such reflection.

In addition, the amplitude of the modal jump can be lower than the amplitude of the inherent laser noise, which makes the SbO drift caused by the modal jump in the green laser no longer a problem. In addition, the variable optical attenuator (VOA) is implemented as an optical switch in the disclosed green laser module, which can greatly reduce the malfunctions and failures related to the laser beam switch (LBS). It should be noted that the present invention is not only good for making the lithography system but also for making any laser in any application (for example, biomedicine, sensor, telecommunications, etc.) the coherence of the laser source destroyed. It should also be noted that a green laser is used as an example in the present invention. However, by selecting appropriate fiber lengths and other components in the disclosed solution, the present invention can be used for any laser source with different wavelengths (for example, red laser, any other visible light laser, UV laser or infrared laser, etc.) )kick in.

The following items can be used to further describe the embodiments: 1. A laser module, which contains: A laser source, which is configured to generate laser light; and The infinite pulse response filter is configured to decorrelate the phase of the components of the laser light, thereby reducing the coherence effect of the laser light. 2. Such as the laser module of Clause 1, in which the laser source is configured to produce green laser light. 3. As the laser module of clause 1, wherein the infinite pulse response filter includes a plurality of optical couplers to form a plurality of optical propagation loops with different optical path lengths. 4. Such as the laser module of Clause 3, in which a plurality of optical propagation loops include: The first optical propagation loop, which has a first optical fiber with a first optical fiber length; A second optical propagation loop having a second optical fiber with a second optical fiber length; and The third optical propagation loop, which has a third optical fiber with a third optical fiber length; The length of the first optical fiber, the length of the second optical fiber and the length of the third optical fiber are all greater than the coherent length of the laser light. 5. Such as the laser module of item 4, of which: The absolute value of the difference between the length of the first optical fiber and the length of the second optical fiber is greater than the coherent length of the laser light. 6. Such as the laser module of Clause 4, in which: The absolute value of the difference between the length of the third fiber and the sum of the length of the first fiber and the length of the second fiber is greater than the coherent length of the laser light. 7. Such as the laser module of item 4, in which: The sum of any integer multiples of any two of the three fiber lengths is not an integer multiple of the other of the three fiber lengths. 8. As the laser module of clause 4, the combination of the first fiber length, the second fiber length and the third fiber length is one of the following: The length of the first optical fiber is 1.17 m, the length of the second optical fiber is 2.63 m, and the length of the third optical fiber is 4.47 m; The length of the first optical fiber is 1.31 m, the length of the second optical fiber is 2.57 m, and the length of the third optical fiber is 4.49 m; The length of the first fiber is 1.67 m, the length of the second fiber is 2.77 m, and the length of the third fiber is 4.57 m; or The length of the first fiber is 1.79 m, the length of the second fiber is 3.73 m, and the length of the third fiber is 5.93 m. 9. The laser module of Clause 3, which further includes an acousto-optic modulator, which is arranged in the optical propagation loop and configured to shift the optical carrier frequency so that the laser The output of the module has a broadened spectrum to further reduce the coherence effect. 10. For example, the laser module of Clause 9, which further includes an optical fiber phase modulator, which is driven by a random phase signal to determine the phase relationship between the different spectral components output by the laser module. Scrambled. 11. Such as the laser module of Clause 1, which further includes a variable optical attenuator, which is configured as an optical switch. 12. Such as the laser module of item 4, in which a plurality of optical couplers include: The first optical coupler includes a first input port connected to a laser source; The second optical coupler includes a first input port connected to a first output port of the first optical coupler; The third optical coupler includes a first input port connected to the second output port of the first optical coupler and a second input port connected to the second output port of the second optical coupler; and A fourth optical coupler, which includes a first input port connected to the first output port of the third optical coupler, a second input port connected to the second output port of the third optical coupler, and connected to the first optical coupler The first output port of the second input port of the device and the second output port connected to the second input port of the second optical coupler. 13. Such as the laser module of item 12, in which: The first optical fiber is arranged between the first output port of the third optical coupler and the first input port of the fourth optical coupler; and The second optical fiber is arranged between the second output port of the third optical coupler and the second input port of the fourth optical coupler. 14. Such as the laser module of item 12, in which: The first optical fiber is arranged between the second output port of the first optical coupler and the first input port of the third optical coupler; and The second optical fiber is arranged between the second output port of the second optical coupler and the second input port of the third optical coupler. 15. Such as the laser module of item 12, in which: The third optical fiber is arranged between the second output port of the fourth optical coupler and the second input port of the first optical coupler; or The third optical fiber is arranged between the first output port of the fourth optical coupler and the second input port of the second optical coupler. 16. Such as the laser module of Article 12, in which: The first optical coupler has a splitting ratio of 10:90; and The second optical coupler, the third optical coupler, and the fourth optical each have a splitting ratio of 50:50. 17. For example, the laser module of item 12, which further includes: The first acousto-optic modulator is arranged between the second output port of the first optical coupler and the first input port of the third optical coupler; and A second acousto-optic modulator is arranged between the second output port of the second optical coupler and the second input port of the third optical coupler. 18. For example, the laser module of item 12, which further includes: The first acousto-optic modulator is arranged between the first output port of the third optical coupler and the first input port of the fourth optical coupler; and The second acousto-optic modulator is arranged between the second output port of the third optical coupler and the second input port of the fourth optical coupler. 19. A weights and measures system, which includes: A multi-color radiation source, which includes a laser module as in Clause 1 and is configured to generate alignment light. 20. A lithography device, which includes the weights and measures system as described in item 19.

Concluding remarks

Although the use of lithography devices in IC manufacturing can be specifically referred to herein, it should be understood that the lithography devices described herein can have other applications, such as manufacturing integrated optical systems, and for magnetic domain memory. Guide and detect patterns, flat panel displays, liquid crystal displays (LCD), thin film magnetic heads, etc. Those familiar with this technology should understand that, in the context of such alternative applications, any use of the term "wafer" or "die" in this article can be regarded as being separately from the more general term "substrate" or "target part". Synonymous. The mentioned herein can be processed before or after exposure in, for example, a coating and development system (usually a tool for applying a resist layer to a substrate and developing the exposed resist), a metrology tool, and/or an inspection tool Substrate. Where applicable, the disclosures in this article can be applied to such and other substrate processing tools. In addition, the substrate can be processed more than once, for example, to produce a multilayer IC, so that the term substrate used herein can also refer to a substrate that already contains multiple processed layers.

Although the above may specifically refer to the use of embodiments of the present invention in the context of optical lithography, it should be understood that the present invention can be used in other applications such as imprint lithography, and is not limited to optical lithography where the context permits. Lithography. In imprint lithography, the configuration in the patterned device defines the pattern produced on the substrate. The configuration of the patterned device can be pressed into the resist layer supplied to the substrate on which the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. After the resist is cured, the patterned device is removed from the resist, leaving a pattern in it.

It should be understood that the terms or terms in this text are for the purpose of description rather than limitation, so that the terms or terms in this specification are to be interpreted by those skilled in the art in accordance with the teachings in this text.

In the embodiments described herein, the terms "lens" and "lens element" can refer to any one or combination of various types of optical components, including refraction, reflection, magnetic, electromagnetic, and electrostatic, as the context permits. Optical components.

In addition, the terms "radiation", "beam" and "light" as used herein cover all types of electromagnetic radiation, including ultraviolet (UV) radiation (for example, with 365 nm, 248 nm, 193 nm, 157 nm or 126 nm Wavelength λ), extreme ultraviolet (EUV or soft X-ray) radiation (for example, having a wavelength in the range of 5 nm to 20 nm, such as 13.5 nm) or hard X-rays operating at less than 5 nm, and such as ion A beam of particles or a beam of electrons. Generally, radiation having a wavelength between about 400 nm and about 700 nm is regarded as visible radiation; radiation having a wavelength between about 780 nm and 3000 nm (or greater) is regarded as IR radiation. UV refers to radiation with a wavelength of approximately 100 nm to 400 nm. In lithography, the term "UV" is also applied to the wavelengths that can be generated by mercury discharge lamps: G-line 436 nm; H-line 405 nm; and/or I-line 365 nm. Vacuum UV or VUV (ie, UV absorbed by gas) refers to radiation having a wavelength of approximately 100 nm to 200 nm. Deep UV (DUV) generally refers to radiation having a wavelength in the range of 126 nm to 428 nm, and in an embodiment, an excimer laser can generate DUV radiation used in a lithography device. It should be understood that radiation having a wavelength in the range of, for example, 5 nm to 20 nm refers to radiation having a certain wavelength band, at least part of which is in the range of 5 nm to 20 nm.

The term "substrate" as used herein generally describes the material to which subsequent layers of material are added. In an embodiment, the substrate itself may be patterned, and the material added on the top of the substrate may also be patterned, or may remain unpatterned.

Although specific embodiments of the present invention have been described above, it should be understood that the present invention can be practiced in other ways than those described. This description is not intended to limit the invention.

It should be understood that the implementation mode chapter rather than the invention content and the invention abstract chapter is intended to explain the scope of the patent application. The Summary of the Invention and Summary of the Invention chapters may describe one or more but not all exemplary embodiments of the present invention as considered by the inventor, and therefore, are not intended to limit the scope of the present invention and the appended patents in any way.

The present invention has been described above with reference to the function building block of the embodiment illustrating the specified function and its relationship. For ease of description, the boundaries of these functional building blocks have been arbitrarily defined in this article. As long as the specified functions are properly performed and the relationship between these functions, the replacement boundary can be defined.

The foregoing description of the specific embodiments will therefore fully expose the general nature of the present invention: without departing from the general concept of the present invention, others can easily apply the knowledge known by those familiar with the art for various applications. Modify and/or adapt such specific embodiments without undue experimentation. Therefore, based on the teachings and guidance presented herein, such adaptations and modifications are intended to be within the meaning and scope of equivalents of the disclosed embodiments.

The breadth and scope of the present invention should not be limited by any of the above-mentioned exemplary embodiments, but should only be defined according to the scope of the following patent applications and their equivalents.

100: Lithography device 100': Lithography device 202: Mark 206: Spot 220: Illumination source 222: Aligning beam 223: Point mirror 224: Objective lens 226: Information carrying beam 228: Self-reference interferometer 230: Sensing Sensor array/sensor grid 232: intensity signal 310: green laser source 410: first optical coupler 410a: first input port 410b: second input port 410c: first output port 410d: second output port 420: second optical coupler 420a: first input port 420b: second input port 420c: first output port 420d: second output port 430: third optical coupler 430a: first input port 430b: second input port 430c: first output port 430d: second output port 440: fourth optical coupler 440a: first input port 440b: second input port 440c: first output port 440d: second output port 450: fifth optical coupler 450a: first input port 450c: first output port 450d: second output port 510: polarization maintaining connector 520: variable optical attenuator 530-1: first acousto-optic modulator 530-2: second acousto-optic modulator Translator 540-1: First RF driver 540-2: Second RF driver 550: Fiber phase modulator AD: Adjuster AS: Alignment sensor B: Radiation beam BD: Beam delivery system C: Target part CO : Condenser f: RF frequency G1: Green laser module G2: Green laser module G3: Green laser module G4: Green laser module G11: Green laser module G12: Green laser module IF: Position Sensor IF1: Position Sensor IF2: Position Sensor IL: Illumination System/Illuminator IN: Integrator L: Length L ₁ : Fiber Length/First Length L ₂ : Fiber Length/Second Length L ₃ : Fiber Length/Third Length LA: Lithography Device LACU: Lithography Device Control Unit LS: Level Sensor M1: Mask Alignment Mark M2: Mask Alignment Mark MA: Patterned Device MT: Support Structure P1: substrate alignment mark P2: substrate alignment mark PM: first positioner PS: projection system PU: processing unit PW: second positioner/substrate positioner/substrate positioning system RF: reference frame SO: radiation source Vw : Speed W: Substrate WT: Substrate table WTa: Substrate table WTb: Substrate table X: Direction Y: Direction Z: Direction λ: Wavelength

The accompanying drawings incorporated herein and forming a part of this specification illustrate the present invention, and together with the description are further used to explain the principles of the present invention and enable those familiar with related art to make and use the present invention.

Fig. 1A is a schematic illustration of a reflection lithography device according to an embodiment;

Fig. 1B is a schematic illustration of a transmission lithography apparatus according to an embodiment;

2 is a schematic block diagram of an alignment sensor for scanning alignment marks according to some embodiments;

3 to 8 illustrate schematic diagrams of exemplary green laser modules according to some embodiments; and

FIG. 9 includes a schematic diagram showing the spectral broadening of the output green laser according to some embodiments.

The features and advantages of the present invention will become more apparent from the detailed description set forth below in conjunction with the drawings. In the drawings, the same reference numerals always identify corresponding elements. In the drawings, the same reference numerals generally indicate the same, functionally similar and/or structurally similar elements. The first appearance of the element is indicated by the leftmost digit in the corresponding icon number. Unless otherwise indicated, the drawings provided throughout the present invention should not be construed as being drawn to scale.

310: Green laser source

410: The first optical coupler

410a: the first input port

410b: second input port

410c: the first output port

410d: second output port

420: second optical coupler

420a: the first input port

420b: second input port

420c: the first output port

420d: second output port

430: third optical coupler

430a: The first input port

430b: second input port

430c: the first output port

430d: second output port

440: The fourth optical coupler

440a: The first input port

440b: second input port

440c: the first output port

440d: second output port

450: Fifth optical coupler

450a: The first input port

450c: the first output port

450d: second output port

510: Polarization maintaining connector

520: Variable optical attenuator

G1: Green laser module

L ₁ : fiber length/first length

L ₂ : Fiber length/second length

L ₃ : fiber length / third length

Claims (15)

A laser module, which includes: A laser source configured to generate laser light; and An infinite pulse response filter, which is configured to decorrelate the phase of the components of the laser light, thereby reducing the coherence effect of the laser light. Such as the laser module of claim 1, wherein the laser source is configured to generate green laser light. Such as the laser module of claim 1, wherein the infinite impulse response filter includes a plurality of optical couplers to form a plurality of optical propagation loops with different optical path lengths. For example, the laser module of claim 3, wherein the plurality of optical propagation loops include: A first optical propagation loop having a first optical fiber having a first optical fiber length; A second optical propagation loop having a second optical fiber with a second optical fiber length; and A third optical propagation loop, which has a third optical fiber having a third optical fiber length; The length of the first optical fiber, the length of the second optical fiber and the length of the third optical fiber are all greater than a coherent length of the laser light. Such as the laser module of claim 4, where: An absolute value of a difference between the first optical fiber length and the second optical fiber length is greater than the coherent length of the laser light. Such as the laser module of claim 4, where: An absolute value of a difference between the third optical fiber length and the sum of the first optical fiber length and the second optical fiber length is greater than the coherent length of the laser light. Such as the laser module of claim 4, where: A sum of any integer multiples of any two of the three fiber lengths is not an integer multiple of the other of the three fiber lengths. Such as the laser module of claim 4, wherein one of the first optical fiber length, the second optical fiber length, and the third optical fiber length is combined into one of the following: The first optical fiber has a length of 1.17 m, the second optical fiber has a length of 2.63 m, and the third optical fiber has a length of 4.47 m; The first optical fiber has a length of 1.31 m, the second optical fiber has a length of 2.57 m, and the third optical fiber has a length of 4.49 m; The first optical fiber has a length of 1.67 m, the second optical fiber has a length of 2.77 m, and the third optical fiber has a length of 4.57 m; or The first optical fiber has a length of 1.79 m, the second optical fiber has a length of 3.73 m, and the third optical fiber has a length of 5.93 m. Such as the laser module of claim 3, which further includes an acousto-optic modulator configured in an optical propagation loop and configured to shift an optical carrier frequency so that the One output of the laser module has a broadened spectrum to further reduce the coherence effect. For example, the laser module of claim 9, which further includes an optical fiber phase modulator, the optical fiber phase modulator is driven by a random phase signal to be between the different spectral components of the output of the laser module The phase relationship is scrambled. Such as the laser module of claim 1, which further includes a variable optical attenuator configured as an optical switch. Such as the laser module of claim 4, wherein the plurality of optical couplers include: A first optical coupler, which includes a first input port connected to the laser source; A second optical coupler including a first input port connected to a first output port of the first optical coupler; A third optical coupler including a first input port connected to a second output port of the first optical coupler and a second input port connected to a second output port of the second optical coupler ;and A fourth optical coupler, which includes a first input port connected to a first output port of the third optical coupler, and a second input port connected to a second output port of the third optical coupler A first output port connected to a second input port of the first optical coupler and a second output port connected to a second input port of the second optical coupler. Such as the laser module of claim 12, where: The first optical fiber is arranged between the first output port of the third optical coupler and the first input port of the fourth optical coupler; and The second optical fiber is arranged between the second output port of the third optical coupler and the second input port of the fourth optical coupler. Such as the laser module of claim 12, where: The first optical fiber is arranged between the second output port of the first optical coupler and the first input port of the third optical coupler; and The second optical fiber is arranged between the second output port of the second optical coupler and the second input port of the third optical coupler. Such as the laser module of claim 12, where: The third optical fiber is arranged between the second output port of the fourth optical coupler and the second input port of the first optical coupler; or The third optical fiber is arranged between the first output port of the fourth optical coupler and the second input port of the second optical coupler.

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