Laser device and method for manufacturing electronic device

Abstract

The invention provides a laser device and a method for manufacturing an electronic device. A laser device is provided with: an oscillator that emits pulsed laser light; a random phase plate disposed in an optical path of the pulse laser light; and an optical pulse stretcher that is disposed in the optical path of the pulse laser light that has passed through the random phase plate, and that spreads the pulse time width of the pulse laser light by transmitting a portion of the pulse laser light and causing the other portion of the pulse laser light to surround at least one circle in a delayed optical path and outputting transmitted light and surrounding light.

Description

Technical Field

[0001] This disclosure relates to methods for manufacturing laser devices and electronic components. Background Technology

[0002] In recent years, with the miniaturization and high integration of semiconductor integrated circuits, there has been a growing demand for higher resolution in semiconductor exposure equipment. Therefore, efforts are underway to shorten the wavelength of light emitted from exposure light sources. For example, KrF excimer laser devices using lasers with an output wavelength of approximately 248 nm and ArF excimer laser devices using lasers with an output wavelength of approximately 193 nm are examples of gas laser devices used for exposure.

[0003] The natural oscillating light from KrF and ArF excimer lasers has a wide spectral linewidth, ranging from 350 to 400 pm. Therefore, if the projection lens is constructed from a material that allows ultraviolet light, such as that of KrF and ArF lasers, to pass through, chromatic aberration may sometimes occur. As a result, resolution may be reduced. Therefore, it is necessary to narrow the spectral linewidth of the laser output from the gas laser device to a level that eliminates chromatic aberration. Thus, in the laser resonator of a gas laser device, a line-narrowing module (LNM) containing narrowing elements (etalon, grating, etc.) is sometimes included to narrow the spectral linewidth. Hereinafter, gas laser devices with narrowed spectral linewidths will be referred to as narrow-bandgap gas laser devices.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2018 / 138819 Summary of the Invention

[0007] One aspect of the laser device disclosed herein includes: an oscillator that emits a pulsed laser; a random phase plate disposed in the optical path of the pulsed laser; and an optical pulse stretcher disposed in the optical path of the pulsed laser after passing through the random phase plate, which causes a portion of the pulsed laser to pass through and causes another portion to circulate at least once in a delayed optical path to output transmitted light and circulated light, thereby extending the pulse duration width of the pulsed laser.

[0008] Another aspect of this disclosure discloses a method for manufacturing an electronic device, comprising the following steps: generating a laser using a laser device, outputting the laser to an exposure device, and exposing the laser onto a photosensitive substrate within the exposure device to manufacture the electronic device. The laser device includes: an oscillator that emits pulsed laser light; a random phase plate disposed in the optical path of the pulsed laser; and a pulse stretcher disposed in the optical path of the pulsed laser after passing through the random phase plate, which causes a portion of the pulsed laser light to pass through and another portion to circulate at least once in a delayed optical path to output transmitted light and circulated light, thereby extending the pulse duration width of the pulsed laser. Attached Figure Description

[0009] The following description, by way of example only, refers to the accompanying drawings to illustrate several embodiments of this disclosure.

[0010] Figure 1 This is an example of a speckle image obtained by photographing a pattern composed of light and dark spots.

[0011] Figure 2 It means Figure 1 The graph shows the histogram of the light and dark areas of the speckle image.

[0012] Figure 3 The structure of the comparative laser device is shown in general.

[0013] Figure 4 This is an illustration of a method for offsetting the beam angles based on the number of beam wraps within the OPS.

[0014] Figure 5 This is an illustration of a method for offsetting the positions of the beams based on the number of beams encircling within the OPS.

[0015] Figure 6 A structural example of the laser device in Embodiment 1 is shown in general.

[0016] Figure 7 This is a schematic diagram illustrating the action of shifting the optical path of surrounding light by a structure composed of a random phase plate and an OPS.

[0017] Figure 8 This is a diagram illustrating an example of a pattern of pixels in a random phase plate.

[0018] Figure 9 It is a diagram showing the change in the electric field of a beam passing through a random phase plate.

[0019] Figure 10 This is a graph showing the change in the electric field of the beam passing through the OPS.

[0020] Figure 11This is a diagram showing the change in electric field caused by the combination of the random phase plate and OPS in Implementation Method 1.

[0021] Figure 12 This is a diagram showing the change in the electric field of the beam when the OPS is positioned near the front (upstream side) and the random phase plate is positioned behind it.

[0022] Figure 13 This indicates the cross-section of the beam emitted from the OPS.

[0023] Figure 14 This is a diagram illustrating the method for measuring the offset when the beam is deflected by the OPS.

[0024] Figure 15 A simplified representation of the structure of an exposure apparatus. Detailed Implementation

[0025] -Table of contents-

[0026] 1. Explanation of terminology

[0027] 1.1 Scattered spots

[0028] 1.2 Random Phase Plate

[0029] 2. Comparative Examples

[0030] 2.1 Structure

[0031] 2.2 Actions

[0032] 2.3 Research Topic

[0033] 3. Implementation Method 1

[0034] 3.1 Structure

[0035] 3.2 Actions

[0036] 3.3 Regarding the changes in the electric field caused by the random phase plate and OPS

[0037] 3.3.1 Changes in the electric field caused by the random phase plate

[0038] 3.3.2 Changes in the electric field caused by the combination of random phase plates and OPS

[0039] 3.3.3 Comparative Example

[0040] 3.3.4 Differences in electric field changes caused by different positional relationships between the random phase plate and the OPS

[0041] 3.4 Regarding the structure of configuring a random phase plate within the delay optical path of the OPS

[0042] 3.5 Regarding the configuration of random phase boards in cases with multiple OPS

[0043] 3.6 Functions and Effects

[0044] 4. Method for determining the offset L caused by OPS

[0045] 5. Manufacturing methods for electronic devices

[0046] 6. About the processor

[0047] 7. Other

[0048] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments described below represent several examples of the present disclosure and do not limit the content of the present disclosure. In addition, the structures and operations described in each embodiment are not necessarily all necessary for the structures and operations of the present disclosure. Furthermore, the same reference numerals are used to denote the same constituent elements, and repeated descriptions are omitted.

[0049] 1. Explanation of terminology

[0050] 1.1 Scattered spots

[0051] "Speckle" refers to the bright and dark spots produced when laser light is scattered in a random medium. Figure 1 This is an example of a speckle image obtained by photographing a pattern composed of light and dark spots. Additionally, Figure 2 It means Figure 1 The graph shows the histogram of the light and dark areas of the speckle image.

[0052] As a speckle evaluation metric, speckle contrast (SC) is commonly used. It is assumed that the standard deviation of the speckle image intensity is... The average intensity of the speckle image is Ip( (If I is marked with a 'pull'), then the speckle contrast SC can be represented by the following formula (1).

[0053]

[0054] 1.2 Random Phase Plate

[0055] The "random phase plate" consists of two types of phase-shifting units: pixels with a transmission phase offset of 0 and pixels with a transmission phase offset of π. The area ratio of pixels with an offset of 0 to those with an offset of π is, for example, 1:1. The pixels in the random phase plate can be regular polygons such as squares or hexagons, but the shape is not limited to regular polygons. The length of a pixel represents the length of one side when the pixel shape is an equilateral triangle or square, and the distance between opposite sides when the pixel shape is a hexagon.

[0056] 2. Comparative Examples

[0057] 2.1 Structure

[0058] Figure 3 The comparative example of the laser device 10 is shown in a simplified manner. The comparative examples disclosed herein are those known only to the applicant and are not publicly known examples endorsed by the applicant.

[0059] The laser device 10 is an excimer laser device including an oscillator (MO) 12, a monitor module 16, an optical shutter 18, and a laser control processor 20. An optical pulse stretcher (OPS) 100, a monitor module 16, and an optical shutter 18 are arranged sequentially in the optical path of the pulsed laser output from the MO 12.

[0060] MO12 includes a chamber 120, a charger 122, a pulsed power module (PPM) 124, a narrowband device 126, and an output coupling mirror 128.

[0061] The narrowbanding device 126 includes a prism beam expander (not shown) and a grating (not shown). The prism beam expander and the grating are configured in a Litterrow configuration to make the incident angle and the diffraction angle coincide.

[0062] The output coupling mirror 128 is, for example, a reflector with a reflectivity of 40% to 60%. The output coupling mirror 128 and the narrowing device 126 constitute an optical resonator. The cavity 120 is disposed in the optical path of the optical resonator.

[0063] The chamber 120 includes a pair of electrodes 130a and 130b, an insulating component 132, a front window 134, and a rear window 136.

[0064] Laser gas of ArF, KrF, XeCl or XeF is sealed in chamber 120.

[0065] Electrode 130b is connected to the high-voltage output terminal of PPM124 via insulating component 132. Electrode 130a is grounded.

[0066] Electrodes 130a and 130b are arranged with a predetermined gap. Electrodes 130a and 130b are discharge electrodes, and the space between electrodes 130a and 130b is called the discharge space (discharge region).

[0067] The front side window 134 and the rear side window 136 are configured to allow the laser generated in the discharge space to pass through.

[0068] PPM124 includes a switch 125 and a charging capacitor (not shown). Switch 125 is connected to a signal line that transmits an on / off signal from the laser control processor 20. Charger 122 is connected to the charging capacitor of PPM124. Charger 122 receives charging voltage data from the laser control processor 20 and charges the charging capacitor of PPM124 at a high voltage.

[0069] OPS100 includes a beam splitter BS and four concave mirrors 101, 102, 103, and 104. The beam splitter BS is positioned in the optical path of the pulsed laser output from MO12. The beam splitter BS is coated with a film that reflects a portion of the incident pulsed laser while allowing another portion to pass through. The reflectivity of the beam splitter BS is preferably 40% to 70%, more preferably about 60%.

[0070] Concave mirrors 101-104 form the delayed optical path of the pulsed laser reflected by the first surface of the beam splitter BS. Concave mirrors 101-104 are all concave mirrors with approximately the same focal length f1.

[0071] Concave mirrors 101 and 102 are configured such that the pulsed laser light reflected from the first surface of the beam splitter BS is reflected by concave mirror 101 and incident on concave mirror 102. Concave mirrors 103 and 104 are configured such that the pulsed laser light reflected from concave mirror 102 is reflected by concave mirror 103 and incident on concave mirror 104. Concave mirror 104 is configured such that the pulsed laser light reflected from concave mirror 104 is incident on a second surface of the beam splitter BS opposite to the first surface.

[0072] Concave mirrors 101 and 102 are configured to invert the image of the pulsed laser reflected from the first surface of the beam splitter BS onto the first surface of the beam splitter BS, forming a first image. Concave mirrors 103 and 104 are configured to return the first image to the beam splitter BS, where it is rotated to the correct orientation and formed into a second image on the second surface of the beam splitter BS. In this case, the optical path length L1 of the delay optical path of the OPS100 is L1 = 8 × f1. The optical path length L1 refers to the length of one full cycle of the delay optical path of the OPS100.

[0073] The beam splitter BS is configured such that pulsed laser light that is not reflected but passes through the first surface of the beam splitter BS is incident on the monitor module 16.

[0074] The monitor module 16 is configured in the optical path of the pulsed laser output from the OPS100. The monitor module 16 includes a beam splitter 162 and a light sensor 164.

[0075] Optical sensor 164 is connected to laser control processor 20, and the detection data of optical sensor 164 is sent to laser control processor 20. Optical shutter 18 is disposed in the optical path of the pulsed laser after passing through monitor module 16, and is configured to switch the output and blocking of the pulsed laser to the outside of laser device 10. Optical shutter 18 is connected to laser control processor 20 via a signal line that transmits the signal for opening and closing the optical shutter.

[0076] The pulsed laser output from the laser device 10 is input into the exposure device 80.

[0077] The laser control processor 20 is connected to the exposure control processor 82. The signal lines between the laser control processor 20 and the exposure control processor 82 include the signal line for the emission trigger signal Tr, the signal line for the target pulse energy Et data, and the signal lines for exchanging other signals.

[0078] Alternatively, an amplifier containing a laser chamber (not shown) can be configured between MO12 and OPS100.

[0079] MO12 can also include a solid-state laser such as a YAG laser instead of an excimer laser. Alternatively, in this case, MO12 can also include a semiconductor optical amplifier (SOA) that cuts out pulsed light from continuous light.

[0080] 2.2 Actions

[0081] When the laser control processor 20 receives the target pulse energy Et and oscillation preparation signal from the exposure control processor 82, it outputs a signal to close the shutter 18, thereby closing the emission outlet of the laser device 10.

[0082] When the laser control processor 20 turns on the switch 125 of PPM124 synchronously with the emission trigger signal Tr at a specified repetition frequency, it applies a high voltage between electrodes 130a and 130b.

[0083] When insulation breakdown occurs between electrodes 130a and 130b, a discharge occurs between the two electrodes, exciting the excimer laser gas. As a result, laser oscillation occurs through an optical resonator composed of a narrowbanding device 126 and an output coupling mirror 128, and the narrowbanded pulsed laser is output from the output coupling mirror 128.

[0084] The pulsed laser output from the output coupling mirror 128 is extended to the specified pulse duration by using OPS100 to pass through the delay optical path multiple times.

[0085] A portion of the pulsed laser light after passing through OPS100 is reflected by beam splitter 162 and incident on optical sensor 164. Optical sensor 164 measures the pulse energy E of the incident pulsed laser light. Data representing this measurement result is sent from optical sensor 164 to laser control processor 20.

[0086] The laser control processor 20 sets the charging voltage of the charger 122 so that the difference between the target pulse energy Et and the measured pulse energy E is equal to the voltage of the target pulse energy Et. E is close to 0.

[0087] When When E enters the permissible range, the laser control processor 20 sends an oscillation preparation completion signal to the exposure control processor 82 and opens the shutter 18. The laser control processor 20 synchronously switches the PPM124 switch 125 with the emission trigger signal Tr from the exposure control processor 82. Thus, pulsed laser is output from MO12, and pulsed laser with pulsed energy Et, expanded by OPS100 and close to the target pulse energy Et, is output from the laser device 10.

[0088] Pulsed laser light output from laser device 10 is incident on exposure device 80, irradiating a resist such as a semiconductor wafer (not shown) with the pulsed laser light.

[0089] 2.3 Research Topic

[0090] To reduce speckle contrast, it is necessary to reduce both temporal and spatial overlap of the pulses. To reduce spatial overlap, methods are known to offset the angle or position of the pulsed laser beam based on the number of wraps in the delay path of the OPS100. Hereafter, the pulsed laser beam is sometimes simply referred to as the "beam".

[0091] Figure 4 This is an explanatory diagram illustrating the method of offsetting the beam angles based on the number of beam wraps within the OPS100. Figure 5 This is an explanatory diagram illustrating the method of offsetting the beam positions based on the number of beam wraps within the OPS100. Figure 4 and Figure 5 In the diagram, solid lines represent the beam output from OPS100 that orbits 0 times within OPS100, dashed lines represent the beam output that orbits 1 time, and dotted lines represent the beam output that orbits 2 times. By adjusting the configuration of concave mirrors 101-104, such as... Figure 4 As shown, the beam angle can be changed according to the number of orbits.

[0092] In addition, by adjusting the configuration of concave mirrors 101-104, such as Figure 5 As shown, the beam position can be changed according to the number of orbits. Furthermore, in Figure 4 , Figure 5 In the accompanying diagrams, the views after the three-circle surround light have been omitted for clarity.

[0093] To reduce speckle contrast, the angle and position offset need to be increased, but in this case, energy loss occurs due to beam vignetting.

[0094] For example, to reduce speckle contrast, if the beam angles are staggered ( Figure 4 If the beam divergence needs to be shifted by about half, then the beam position needs to be shifted. Figure 5 If so, the beam size needs to be offset by about half.

[0095] The requirement is to provide a laser device that reduces speckle contrast, i.e., reduces beam coherence, and suppresses and reduces energy loss.

[0096] 3. Implementation Method 1

[0097] 3.1 Structure

[0098] Figure 6 A structural example of the laser device 10A according to Embodiment 1 is shown in general. Regarding... Figure 6 The laser device 10A shown is described in conjunction with... Figure 3 The differences in the structure shown are as follows. The laser device 10A has a random phase plate 14 between OPS100 and MO12. Hereinafter, the random phase plate will also be referred to as "RPP".

[0099] The random phase plate 14 can be added at any position between OPS100 and MO12. For example, if there are other optical elements between OPS100 and MO12, the random phase plate 14 can be positioned upstream or downstream of those optical elements.

[0100] Concave mirrors 101, 102, 103, and 104 are positioned such that the emitted light paths are offset according to the number of encirclements of OPS100. Sometimes, even unintentionally, the positions of concave mirrors 101, 102, 103, and 104 result in the emitted light paths being offset according to the number of encirclements. Concave mirrors 101, 102, 103, and 104 are an example of "multiple mirrors" in this disclosure.

[0101] Other structures and Figure 3 The structure of the laser device 10 shown is the same.

[0102] 3.2 Actions

[0103] In the laser device 10A, a random phase plate 14 is arranged near (upstream) the OPS100, and the optical path of the surrounding light is shifted according to the number of surrounds by the OPS100.

[0104] Figure 7 This is an illustrative diagram schematically showing the action of shifting the optical path of the surrounding light by combining the random phase plate 14 and OPS100.

[0105] The pulsed laser output from MO12 passes through random phase plate 14. The beam after passing through random phase plate 14 is incident on OPS100. Within OPS100, the beam is split by beam splitter BS. One beam passes through beam splitter BS and exits outside OPS100. Part of the other beam circles within OPS100 and is reflected by beam splitter BS before exiting outside OPS100; the remaining part passes through beam splitter BS and circles within OPS100 once more. This process is repeated for the surrounding beam.

[0106] The beam of the surrounding light, which has completed at least one revolution in the delayed optical path of OPS100, is offset from the beam of the transmitted light that has completed zero revolutions and passed through the beam splitter BS, and is emitted out of OPS100. The offset optical paths of the transmitted light and the surrounding light are preferably parallel. The offset L of the optical path during parallel movement is preferably greater than or equal to the pixel size of the random phase plate 14.

[0107] Figure 8 This is a schematic diagram illustrating an example of a pattern of pixels in a random phase plate 14. Figure 8 An example of a random phase plate 14 with square pixels arranged in two dimensions is shown. The pixel size D of the random phase plate 14 can be defined as the length of one side of a square pixel. In order to suppress the increase of beam divergence and further reduce the vignetting of the beam downstream of the random phase plate 14, the pixel size D is preferably set to satisfy the following equation (2).

[0108]

[0109] In equation (2), 'a' is the size of the coherent region. In the case of a typical excimer laser device, 'a' is greater than 0.1 mm and less than 0.5 mm.

[0110] Preferably, the pixel size D is 0.5a or more, and in the case of an excimer laser device, the pixel size D is 0.05mm or more. Furthermore, it is more preferable that the pixel size D satisfies 0.5a < D.

[0111] like Figure 7 As shown, when the offset L of the optical path of the surrounding light output from OPS100 is parallel to the pixel size D of the random phase plate 14, speckle can be reduced more efficiently, and therefore it is preferred.

[0112] Furthermore, when the offset L is less than twice the pixel size D, the beam size will not become too large, and the loss caused by the vignetting of the downstream beam will be smaller, which is therefore preferred. That is, the offset L preferably satisfies the following equation (3).

[0113]

[0114] Offset L is an example of "misalignment" in this disclosure. D≤L is an example of "misalignment greater than or equal to a pixel size" in this disclosure. L≤2D is an example of "misalignment less than or equal to twice the pixel size" in this disclosure.

[0115] 3.3 Regarding the changes in the electric field caused by the random phase plate and OPS

[0116] 3.3.1 Changes in the electric field caused by the random phase plate

[0117] Figure 9 This is a diagram showing the change in the electric field of the beam passing through the random phase plate 14.

[0118] E(r,t) is a complex function representing the electric field. r = (x,y) represents the position on the beam, and t represents the time. θ(r) is a function representing the phase distribution of the random phase plate 14, which is randomly distributed as 0 or π.

[0119] When the beam passes through the random phase plate 14, the phase component of the electric field changes, and the electric field of the beam changes from... Figure 9 E shown on the left in The change is shown as E on the right. out .

[0120] 3.3.2 Changes in electric field caused by OPS

[0121] Figure 10 This is a graph showing the change in the electric field of the beam passing through the OPS100. Figure 10 E0, E1, and E2 shown on the right represent the electric fields of the 0-cycle surrounding light, the 1-cycle surrounding light, and the 2-cycle surrounding light, respectively.

[0122] like Figure 10 As shown, when the electric field E in When incident on OPS100, the electric field E after passing through OPS100 out Become like Figure 10 The right side shows the overlap of the electric fields of the surrounding light.

[0123] exist Figure 10 The optical path of the beam deflects whenever it orbits within the OPS100. r, time delay t.

[0124] a0, a1, and a2 are coefficients corresponding to the intensity changes of the beam during each rotation in the OPS, determined by the reflectivity of the beam splitter BS within the OPS100 and the propagation loss within the OPS100. Since the OPS100 is a relay optical system, it is assumed that even with beam rotation, the function of the electric field will not change except for the shift in position r on the beam relative to time t.

[0125] 3.3.2 Changes in the electric field caused by the combination of random phase plates and OPS

[0126] Figure 11 This is a diagram showing the change in electric field caused by the combination of the random phase plate 14 and OPS100 in Embodiment 1.

[0127] exist Figure 11 In the middle, E in E represents the electric field incident on the random phase plate 14. a This represents the electric field after the beam passes through the random phase plate 14.

[0128] When the beam passes through the random phase plate 14 and then through the OPS100, the electric field E of the beam output from the OPS100 is... out as follows.

[0129]

[0130] In the above equation, the position r of the phase portion is offset during each orbit. r. This is the same case where the position of the random phase plate 14 changes with each orbit in the OPS.

[0131] 3.3.3 Comparative Example

[0132] For comparison, the change in electric field is explained in a manner that reverses the positional relationship between the random phase plate 14 and the OPS100.

[0133] Figure 12 This is a diagram showing the change in the electric field of the beam when the OPS100 is positioned near the front (upstream side) and the random phase plate 14 is positioned behind it.

[0134] exist Figure 12 In the middle, E 0a E 1a and E 2a This represents the electric field of each surrounding beam after passing through OPS100. The electric field E of the beam output from the random phase plate 14 after the beam passes through OPS100 and then through the random phase plate 14. out as follows.

[0135]

[0136] In the above equation, since the random phase plate 14 is stationary, the position r of the phase portion is constant and independent of the surrounding area.

[0137] 3.3.4 Differences in electric field changes caused by different positional relationships between the random phase plate and the OPS

[0138] Will Figure 11 The structure of Implementation Method 1 described in the text is similar to Figure 12By comparing the comparative examples described, it can be seen that the final output electric field E of both is... out The position r of the phase portion is different.

[0139] When the random phase plate 14 is located near the OPS100 ( Figure 11 In OPS, during each orbit, the position r of the phase portion changes from r→r+ r→r+2 The r→… pattern changes. This has the same effect as the random position change of phase plate 14 during each orbit in OPS.

[0140] That is, as in implementation method 1 ( Figure 11 With the structure of OPS100 positioned behind the random phase plate 14, when the optical path of the beam is deflected by OPS100, the same effect as moving the random phase plate 14 can be obtained even if the random phase plate 14 is stationary.

[0141] Therefore, compared to the case where the beam is deflected only by OPS100 ( Figure 5 Compared to the structure of implementation method 1, Figure 11 In this process, coherence is further reduced, thus increasing the effect of reducing speckle contrast.

[0142] Figure 13 The cross-section LC of the beam emitted from OPS100 is shown. The beam emitted from OPS100 includes the transmitted light (0-circle surrounding light) and the surrounding light. In the case of the laser device 10A of Embodiment 1, Figure 13 The beam at point A shown passes through different positions of the random phase plate 14 depending on the number of orbits, thus efficiently reducing coherence as explained above.

[0143] On the other hand, Figure 12 In the comparative example shown, the beam at point A passes through the same position of the subsequent random phase plate 14 regardless of the number of orbits, therefore... Figure 11 In comparison, coherence has a smaller reduction effect.

[0144] To reduce laser coherence, it is necessary to accumulate beams with little or no correlation. Misaligning the random phase plate 14 by pixel size D effectively eliminates correlation. Furthermore, in practice, since the number of pixels in the random phase plate 14 is finite, the correlation is not completely zero, but it can be considered close to zero in practical applications.

[0145] Therefore, the offset of the random phase plate 14 required to reduce coherence is equal to the pixel size D of the random phase plate 14.

[0146] 3.4 Regarding the structure of configuring a random phase plate within the delay optical path of the OPS

[0147] As another method to reduce coherence, it is also considered to configure a random phase plate 14 within the optical path of OPS100. However, in this case, the beam passes through the random phase plate 14 each time it orbits, resulting in increased beam divergence and making it difficult to suppress beam vignetting. Therefore, it is preferable to configure the random phase plate 14 in the optical path between the oscillator and OPS100, rather than within the optical path of OPS100.

[0148] 3.5 Regarding the configuration of random phase boards in cases with multiple OPS

[0149] The laser device 10A has one OPS 100 downstream of the random phase plate 14, but it can also have multiple OPSs downstream of the random phase plate 14. For example, the laser device 10A can also have a structure that not only has the first OPS 100, but also has a second OPS (not shown) downstream of the OPS 100. Alternatively, the laser device 10A can also have a structure that has a third OPS (not shown) further downstream of the second OPS.

[0150] In the case of a laser device with multiple OPSs, it is preferable to arrange a random phase plate 14 in the optical path between the first-stage OPS and the oscillator. Therefore, a similar reduction in coherence is expected in subsequent OPSs.

[0151] 3.6 Functions and Effects

[0152] According to the laser device 10A, energy loss caused by beam vignetting is suppressed, and beam coherence is reduced efficiently, thereby effectively reducing speckle contrast.

[0153] 4. Method for measuring the optical path offset L caused by OPS

[0154] Figure 14 This diagram illustrates the method for measuring the offset L of the optical path during each rotation when the beam is shifted by the OPS100. The offset L can be measured through the following steps.

[0155] [Step 1] First, as Figure 14 As shown in the upper section, the beam profile BP_all of the beam emitted from the OPS100 is measured. The beam profile BP_all is obtained by accumulating the beam profiles of each of the 0-turn, 1-turn, 2-turn, ... turns. Furthermore, the beam profiles BP_all and BP_0 are measured immediately after the beam splitter BS using a beam analyzer or similar instrument.

[0156] [Step 2] Next, in OPS100, the beam profile BP_0 is measured while the surrounding optical path is blocked. By blocking the surrounding optical path, the beam profile BP_0 of only the 0-cycle surrounding light is obtained (refer to...). Figure 14 (Middle section).

[0157] [Step 3] Calculate the difference BP_diff between the beam profile BP_all and the beam profile BP_0 (refer to...) Figure 14 (The next paragraph).

[0158] [Step 4] By comparing the beam profile BP_0 and the difference BP_diff, the offset L of the beam profile is obtained.

[0159] 5. Manufacturing methods for electronic devices

[0160] Figure 15 A simplified representation of the structure of the exposure apparatus 80 is shown. Figure 15 In this exposure apparatus 80, an illumination optics system 804 and a projection optics system 806 are included. The illumination optics system 804 uses a laser incident from the laser device 10A to illuminate a mask pattern (not shown) disposed on a mask stage RT. The projection optics system 806 projects the laser light transmitted through the mask onto a workpiece (not shown) disposed on a workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist. The exposure apparatus 80 exposes the workpiece with laser light reflecting the mask pattern by synchronously and parallelly moving the mask stage RT and the workpiece stage WT. After transferring the mask pattern onto the semiconductor wafer through the above exposure process, semiconductor devices can be manufactured through multiple processes.

[0161] 6. About the processor

[0162] Processors such as laser control processor 20 and exposure control processor 82 can also be physically configured in hardware to execute the various processes included in this disclosure. For example, the processor can also be a computer, which includes a memory storing control programs that define various processes and a processing device for executing the control programs. The control programs can be stored in a single memory or separately in multiple physically separate memories, defining various processes through the control programs as a collection of these memories. The processing device can be a general-purpose processing device such as a CPU or a special-purpose processing device such as a GPU.

[0163] Furthermore, the processor can also be programmed in software to perform the various processes included in this disclosure. For example, the processor can also have the functions of performing various processes installed in a special-purpose device such as an ASIC or a programmable device such as an FPGA.

[0164] The various processes included in this disclosure can be executed by a single computer, a single dedicated device, or a single programmable device, or can be executed collaboratively by multiple physically separate computers, multiple dedicated devices, or multiple programmable devices. The various processes can also be executed by a combination of at least two of more than one computer, more than one dedicated device, and more than one programmable device.

[0165] Figure 3 and Figure 6 The laser control processor 20 and exposure control processor 82 shown can be processed by the processor and memory after being converted into digital signals by analog electrical signal processing circuitry or AD converter to perform the processing described in each embodiment.

[0166] Furthermore, processing can be divided into multiple processing units based on different processing functions, or it can be performed in a single processing unit. For example, the laser control processor 20 and the exposure control processor 82 can be processed in a single processing unit. These choices are made appropriately based on factors such as processing speed and accuracy.

[0167] 7. Other

[0168] The foregoing description is not limiting but merely illustrative. Therefore, it will be apparent to those skilled in the art that modifications can be made to the embodiments of this disclosure without departing from the claims. Furthermore, combinations of embodiments of this disclosure will also be apparent to those skilled in the art.

[0169] Unless explicitly stated otherwise, all terms used in this specification and claims should be interpreted as “non-restrictive.” For example, terms such as “comprising,” “having,” “possessing,” and “complementing” should be interpreted as “not excluding the presence of elements other than those described.” Furthermore, the modifier “a” should be interpreted as meaning “at least one” or “one or more.” Additionally, the phrase “at least one of A, B, and C” should be interpreted as “A,” “B,” “C,” “A+B,” “A+C,” “B+C,” or “A+B+C.” Moreover, it should be interpreted as also including combinations of these elements with portions other than “A,” “B,” and “C.”

Claims

1. A laser device comprising: An oscillator that emits pulsed laser light; A random phase plate, which is disposed in the optical path of the pulsed laser; and An optical pulse stretcher is configured in the optical path of the pulsed laser after passing through the random phase plate, allowing a portion of the pulsed laser to pass through and another portion to circle at least once in the delayed optical path to output transmitted light and circling light, thereby extending the pulse time width of the pulsed laser.

2. The laser device according to claim 1, wherein, The transmitted light and the surrounding light output from the optical pulse stretcher have their respective optical paths staggered.

3. The laser device according to claim 2, wherein, The light paths of the staggered transmitted light and the surrounding light are parallel.

4. The laser device according to claim 2, wherein, The optical pulse stretcher includes multiple mirrors that form the delayed optical path. The plurality of mirrors are configured such that the delayed optical path is offset from the optical path of each of the surrounding lights when the number of surrounding lights is 2 or more.

5. The laser device according to claim 2, wherein, The offset of the optical path generated each time the surrounding light circles once in the delayed optical path is greater than or equal to the pixel size of the random phase plate.

6. The laser device according to claim 5, wherein, The offset is less than twice the pixel size.

7. The laser device according to claim 1, wherein, When the size of the coherent region of the pulsed laser emitted from the oscillator is 'a', the pixel size of the random phase plate is 0.5a or greater.

8. The laser device according to claim 1, wherein, The pixel size of the random phase plate is 0.05mm or larger.

9. The laser device according to claim 1, wherein, The optical pulse stretcher includes a beam splitter and a concave mirror.

10. The laser device according to claim 9, wherein, The delayed optical route is composed of multiple concave mirrors.

11. The laser device according to claim 1, wherein, The oscillator includes an excimer laser device.

12. The laser device according to claim 1, wherein, A second optical pulse stretcher is provided downstream of the first optical pulse stretcher, which serves as the optical pulse stretcher.

13. The laser device according to claim 12, wherein, A third optical pulse stretcher is located downstream of the second optical pulse stretcher.

14. The laser device according to claim 1, wherein, The random phase plate is stationary.

15. A method for manufacturing an electronic device, wherein, The manufacturing method of the electronic device includes the following steps: Laser is generated by a laser device. The laser is output to the exposure device. The laser is used to expose a photosensitive substrate within the exposure apparatus to manufacture electronic devices. The laser device includes: An oscillator that emits pulsed laser light; A random phase plate, which is disposed in the optical path of the pulsed laser; and An optical pulse stretcher is configured in the optical path of the pulsed laser after passing through the random phase plate, allowing a portion of the pulsed laser to pass through and another portion to circle at least once in the delayed optical path to output transmitted light and circling light, thereby extending the pulse time width of the pulsed laser.

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