TWI712831B - Optical device for a lithography apparatus and lithography apparatus - Google Patents
Optical device for a lithography apparatus and lithography apparatus Download PDFInfo
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- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70216—Mask projection systems
- G03F7/70258—Projection system adjustments, e.g. adjustments during exposure or alignment during assembly of projection system
- G03F7/70266—Adaptive optics, e.g. deformable optical elements for wavefront control, e.g. for aberration adjustment or correction
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- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
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- G02B7/182—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors for mirrors
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- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
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Abstract
Description
本申請案主張2015年12月15日申請之德國專利申請案DE 10 2015 225 263.9的優先權,其整體內容以引用的方式併入本文。
This application claims the priority of the German
本發明關於用於微影設備的一光學裝置及一微影設備。 The present invention relates to an optical device and a lithography equipment used in lithography equipment.
微影是用於微細加工以圖案化基板主體的薄膜的部分的製程。特別地,微影用於積體電路的製造。微影製程是使用包含照明系統及投射系統的微影設備而進行。使用光將幾何圖案從光罩轉移至基板上稱作光阻的光敏感化學層。光罩由照明系統照明。投射系統將幾何圖案投射至位在投射系統之影像平面的基板上。 Lithography is a process for microfabrication to pattern the part of the thin film of the substrate body. In particular, lithography is used in the manufacture of integrated circuits. The lithography process is performed using lithography equipment including an illumination system and a projection system. Light is used to transfer the geometric pattern from the photomask to a photosensitive chemical layer called photoresist on the substrate. The light shield is illuminated by the lighting system. The projection system projects the geometric pattern onto the substrate on the image plane of the projection system.
受到摩爾定律的驅動及追求更小的結構,特別是在積體電路的製造上,目前正在開發EUV微影設備,其使用波長在5nm至30nm、特別是13.5nm的光。「EUV」表示「極紫外光」。由於多數材料對在此波長的光具有高吸收,因此在這類EUV微影設備中需要使用反射光學元件(即反射鏡)來取代之前的折射光學元件(即透鏡)。 Driven by Moore's Law and the pursuit of smaller structures, especially in the manufacture of integrated circuits, EUV lithography equipment is currently being developed, which uses light with a wavelength of 5nm to 30nm, especially 13.5nm. "EUV" means "extreme ultraviolet light." Since most materials have high absorption of light at this wavelength, it is necessary to use reflective optical elements (ie mirrors) to replace the previous refractive optical elements (ie lenses) in this type of EUV lithography equipment.
EUV微影設備中的反射鏡可例如緊固至所謂的力框(force frame)。每一反射鏡可在高達六個自由度中操縱。這允許反射鏡相對彼此高度準確地定位,例如在pm範圍。在此方式中,光學特性的改變(例如由於熱擾動)可在微影設備的操作期間被補償。 The mirror in the EUV lithography device can be fastened, for example, to a so-called force frame (force frame). Each mirror can be manipulated in up to six degrees of freedom. This allows the mirrors to be positioned with a high degree of accuracy relative to each other, for example in the pm range. In this way, changes in optical characteristics (for example due to thermal disturbances) can be compensated during the operation of the lithography apparatus.
最近,已發現可透過在微影設備的操作期間(亦即,即時的)變形光學元件(例如反射鏡)而獲得更先進的光學誤差校正。 Recently, it has been discovered that more advanced optical error correction can be obtained by deforming optical elements (such as mirrors) during the operation of the lithography apparatus (ie, instant).
舉例來說,DE 10151919 A1描述(參考該文件的圖1及圖2)包含四個柱2的反射鏡1。致動器4將相對的柱2拉向反射鏡1的光學軸3、或是將相對的柱2推離光學軸3。因此,光學元件1變形。
For example, DE 10151919 A1 describes (refer to Figures 1 and 2 of the document) a mirror 1 containing four
JP 2013-106014 A在圖2中描述了可變形的反射鏡22。多個反射鏡柱24配置在反射鏡22的後端面22e。負載供應系統58組態以位移相應反射鏡柱24的尖端,以將負載引入至反射鏡22的後端面22e並因此而變形反射鏡22的反射表面22d。 JP 2013-106014 A describes a deformable mirror 22 in FIG. 2. The plurality of mirror posts 24 are arranged on the rear end surface 22 e of the mirror 22. The load supply system 58 is configured to displace the tip of the corresponding mirror column 24 to introduce a load to the rear end surface 22e of the mirror 22 and thereby deform the reflective surface 22d of the mirror 22.
本發明的目的為提供用於微影設備的一改良光學裝置。 The object of the present invention is to provide an improved optical device for lithography equipment.
此目的由包含一光學元件、一致動器、及一補償單元的用於微影設備的一光學裝置來達成。光學元件在至少一方向上變形時具有一正剛性(positive stiffness)。致動器組態用以在至少一方向上變形光學元件。補償單元在至少一方向上具有一負剛性以至少部分地補償光學元件的正剛性。 This objective is achieved by an optical device for lithography equipment including an optical element, an actuator, and a compensation unit. The optical element has a positive stiffness when deformed in at least one direction. The actuator configuration is used to deform the optical element in at least one direction. The compensation unit has a negative rigidity in at least one direction to at least partially compensate the positive rigidity of the optical element.
「負剛性」係定義為產生傾向在至少一方向上變形光學元件的力或力矩的剛性,且隨著光學元件在至少一方向上的變形增加而增加(或保持不變)。負剛性因此抵消正剛性,因此降低(或者甚至消除)變形光學元件所需的力。負剛性的另一特徵為其較佳地不需任何外部的能量供應。而是,負剛性依靠儲存於機械系統或磁場中的能量且不依賴任何外部的能量供應。 "Negative rigidity" is defined as rigidity that generates force or moment that tends to deform the optical element in at least one direction, and increases (or remains unchanged) as the deformation of the optical element in at least one direction increases. The negative rigidity therefore counteracts the positive rigidity, thus reducing (or even eliminating) the force required to deform the optical element. Another feature of negative rigidity is that it preferably does not require any external energy supply. Rather, negative rigidity relies on the energy stored in the mechanical system or magnetic field and does not rely on any external energy supply.
本發明所基於的一概念包含將變形光學元件所需的力分成兩個分量,即準靜態力(quasi-static force)及動態力。準靜態力為變形光學元件本身所需。需注意,此處的「變形光學元件」是指整個光學元件被變形或其一或多個部分被變形。準靜態力主要取決於光學元件的(正)剛性。剛性由製成光學元件的材料(例如玻璃或陶瓷)的E-模量以及光學元件的幾何形狀所決定。動態力為加速光學元件的質量所需。此力主要取決於光學元件的密度、幾何變形輪廓以及作為時間的函數的變形軌跡。 A concept on which the present invention is based includes dividing the force required to deform an optical element into two components, namely quasi-static force and dynamic force. The quasi-static force is required to deform the optical element itself. It should be noted that the "anamorphic optical element" here means that the entire optical element is deformed or one or more parts thereof are deformed. The quasi-static force mainly depends on the (positive) rigidity of the optical element. The rigidity is determined by the E-modulus of the material (for example, glass or ceramic) from which the optical element is made and the geometric shape of the optical element. Dynamic force is required to accelerate the quality of optical components. This force mainly depends on the density of the optical element, the geometric deformation profile and the deformation trajectory as a function of time.
因為光學校正所需之光學元件的移動量小(一般範圍在數微米),且同時用於光學校正的時窗(time window)相當大(例如1/30秒),因此所需的動態力為小。另一方面,光學元件的剛性相對大,因此用以變形光學元件的靜態力需遠大於動態力。 Because the amount of movement of the optical components required for optical correction is small (generally within a few microns), and the time window used for optical correction is quite large (for example, 1/30 second), the required dynamic force is small. On the other hand, the rigidity of the optical element is relatively large, so the static force used to deform the optical element must be much greater than the dynamic force.
以目前所提供的(接近)零的剛性配置,致動器現在僅需傳遞動能以及補償任何摩擦耗損所需的能量。例如在10ms的移動時間內將質量1公斤的反射鏡移動1μm以上需要10mm/s2的加速度。因此,需要10mN的力,其可由例如勞侖茲式致動器(亦稱作音圈致動器)在功率耗損低於1mW下輕易地傳遞。 With the (near) zero rigid configuration currently provided, the actuator now only needs to transmit kinetic energy and the energy required to compensate for any friction loss. For example, to move a mirror with a mass of 1 kg by more than 1 μm within a moving time of 10 ms requires an acceleration of 10 mm/s 2 . Therefore, a force of 10 mN is required, which can be easily transmitted by, for example, a Lorentz-type actuator (also called a voice coil actuator) with a power loss of less than 1 mW.
用以補償光學元件的正剛性所需的負剛性一般將在105到106N/m的等級。針對1-μm的偏移,將需要1N的力。在此範例中,這對應所需動態力的100倍,因此大得多。 The negative rigidity required to compensate for the positive rigidity of the optical element will generally be on the order of 10 5 to 10 6 N/m. For a 1-μm offset, a force of 1N will be required. In this example, this corresponds to 100 times the required dynamic force, so it is much greater.
由於此設計,根據本發明的致動器僅需提供動態力,且就算有的話,則提供小的靜態力。因此,由致動器所提供的總力相較於已知的解決方案明顯較小。 Due to this design, the actuator according to the present invention only needs to provide dynamic force, and if any, provide small static force. Therefore, the total force provided by the actuator is significantly smaller than the known solutions.
一般而言,所有類型的致動器將產生顯著的熱,其無法在不增加干擾的情況下被取出,例如冷卻水振動。然而,由於根據本發明解決方案所需的力係大幅地降低,實質上不需要額外的熱移除。 Generally speaking, all types of actuators will generate significant heat, which cannot be removed without increasing interference, such as cooling water vibration. However, since the force system required for the solution according to the present invention is greatly reduced, there is essentially no need for additional heat removal.
本發明的致動器較佳為勞侖茲致動器(Lorentz actuator)。然 而,在某些應用中,其他類型的致動器(例如壓電致動器或氣動致動器)也是可行的。 The actuator of the present invention is preferably a Lorentz actuator. Of course However, in some applications, other types of actuators (such as piezoelectric actuators or pneumatic actuators) are also feasible.
勞侖茲致動器的另一優點為其小的反應時間,其使勞侖茲致動器特別適用於即時的光學誤差校正,例如「晶粒到晶粒(die to die)」或甚至「晶粒內(intra-die)」。「晶粒到晶粒」是指在單一晶圓上的兩個連續晶粒的曝光之間的時窗中變形光學元件。「晶粒內」是指在單一晶粒的掃描期間的時窗中針對光學校正而變形光學元件。 Another advantage of the Lorentz actuator is its small response time, which makes the Lorentz actuator particularly suitable for real-time optical error correction, such as "die to die" or even "die to die". "Intra-die". "Die-to-die" refers to deforming an optical element in the time window between the exposure of two consecutive dies on a single wafer. "In-die" refers to deforming the optical element for optical correction in the time window during the scanning of a single die.
勞侖茲致動器相較於例如壓電致動器的另一優點為其可操作於開迴路控制系統中,因為其表現出較少或沒有磁滯、漂移或其他不準確性。 Another advantage of Lorentz actuators over, for example, piezoelectric actuators is that they can be operated in open-loop control systems because they exhibit less or no hysteresis, drift, or other inaccuracies.
根據一具體實施例,補償單元組態以在至少一方向上於光學元件上產生一第一最大力,且致動器組態以在至少一方向上於光學元件上產生一第二最大力,其中第一最大力比第二最大力大N倍,其中N>5,較佳為N>10,更佳為N>50。 According to a specific embodiment, the compensation unit is configured to generate a first maximum force on the optical element in at least one direction, and the actuator is configured to generate a second maximum force on the optical element in at least one direction, wherein the first A maximum force is N times greater than the second maximum force, where N>5, preferably N>10, more preferably N>50.
「最大力」指在使用光學裝置製造單一晶粒或整個晶圓的循環中所發現的最大力。發現N>5、較佳為>10且更佳為N>50將給出足夠小的致動器力,且同時具有良好的系統穩定度以便於開迴路控制。 "Maximum force" refers to the maximum force found in the cycle of manufacturing a single die or an entire wafer using an optical device. It is found that N>5, preferably>10, and more preferably N>50 will give a sufficiently small actuator force, and at the same time have good system stability to facilitate open loop control.
根據另一具體實施例,補償單元組態以在至少一方向上於光學元件上產生一第一力,且致動器組態以在至少一方向上於光學元件上產生一第二力,其中第一力具有一第一最大時間導數(first maximum time derivative),且第二力具有一第二最大時間導數,其中第二最大時間導數比第一最大時間導數大M倍,其中M>10,較佳為M>100 According to another embodiment, the compensation unit is configured to generate a first force on the optical element in at least one direction, and the actuator is configured to generate a second force on the optical element in at least one direction, wherein the first force The force has a first maximum time derivative, and the second force has a second maximum time derivative, where the second maximum time derivative is M times larger than the first maximum time derivative, where M>10, preferably M>100
「最大時間導數」為在使用光學裝置製造單一晶粒或整個晶圓的循環中所發現的最大導數。發現所給定的數值M將給出高度動態變形,同時使補償單元保持簡單。 The "maximum time derivative" is the largest derivative found in the cycle of manufacturing a single die or an entire wafer using an optical device. It is found that the given value M will give a highly dynamic deformation while keeping the compensation unit simple.
根據另一具體實施例,補償單元的負剛性為光學元件的正 剛性的0.9倍至0.99倍。 According to another specific embodiment, the negative rigidity of the compensation unit is the positive The rigidity is 0.9 times to 0.99 times.
已發現負剛性對正剛性的此比例給出小的致動器力,同時給出良好的動態穩定度。理想上會希望具有100%的補償,使得負剛性對正剛性的比例應等於1。在此情況中,由於光學元件的彈性所導致的正剛性完全被補償單元的負剛性所補償。然而,這也表示反射鏡在任何變形狀態下係處於力平衡,且將保持在這種變形狀態中。這可能不是所希望的,因為在故障的情況下,會希望使反射鏡回到特定的原始形狀。因此,最好使負剛性補償稍微小於100%,例如在90%到99%之間。 It has been found that this ratio of negative rigidity to positive rigidity gives a small actuator force while giving good dynamic stability. Ideally, 100% compensation is desired, so that the ratio of negative rigidity to positive rigidity should be equal to one. In this case, the positive stiffness due to the elasticity of the optical element is completely compensated by the negative stiffness of the compensation unit. However, this also means that the mirror is in force balance under any deformed state and will remain in this deformed state. This may not be desirable because in the event of a malfunction, it may be desirable to return the mirror to a certain original shape. Therefore, it is best to make the negative stiffness compensation slightly less than 100%, for example between 90% and 99%.
根據另一具體實施例,光學元件的正剛性及補償單元的負剛性之間的差異大於零。 According to another specific embodiment, the difference between the positive rigidity of the optical element and the negative rigidity of the compensation unit is greater than zero.
因此,在中性狀態下,即當致動器關閉(無電力)或故障並因此而沒有提供力時,光學元件的狀態、特別是其變形的程度總是被限定。光學元件將總是回到其原始形狀。 Therefore, in a neutral state, that is, when the actuator is turned off (no power) or malfunctions and therefore no force is provided, the state of the optical element, in particular the degree of its deformation, is always limited. The optical element will always return to its original shape.
根據另一具體實施例,光學元件在至少一方向上的變形係藉由光學元件的平面外彎曲(out-of-plane bending)而獲得。 According to another specific embodiment, the deformation of the optical element in at least one direction is obtained by out-of-plane bending of the optical element.
「平面外彎曲」目前是指對垂直於光學元件之光學軸的一軸彎曲。 "Out-of-plane bending" currently refers to one-axis bending perpendicular to the optical axis of the optical element.
根據另一具體實施例,補償單元包含磁鐵,特別是永久磁鐵、或至少一彈簧。 According to another specific embodiment, the compensation unit comprises a magnet, in particular a permanent magnet, or at least one spring.
這類組件也非常適合用以獲得負剛性。彈簧可為機械彈簧,例如片簧或螺旋彈簧。 Such components are also very suitable for obtaining negative rigidity. The spring may be a mechanical spring, such as a leaf spring or a coil spring.
根據另一具體實施例,補償單元(特別是至少一彈簧)係組態以在平面內預載(preload)光學元件。 According to another embodiment, the compensation unit (especially the at least one spring) is configured to preload the optical element in the plane.
「平面內」是指由補償單元所產生的力作用在平行於光學元件的延伸平面的方向中。因此,使用屈曲效應(buckling effect)而獲得負剛性。 "In-plane" means that the force generated by the compensation unit acts in a direction parallel to the extension plane of the optical element. Therefore, the buckling effect is used to obtain negative rigidity.
根據另一具體實施例,光學裝置包含一基底,其中磁鐵由緊固至光學元件的第一磁鐵以及分別緊固至基底的第二磁鐵及第三磁鐵所組成,第一磁鐵可在第二磁鐵及第三磁鐵之間移動。 According to another embodiment, the optical device includes a substrate, wherein the magnet is composed of a first magnet fastened to the optical element, and a second magnet and a third magnet fastened to the substrate, respectively. The first magnet can be mounted on the second magnet. And the third magnet.
此組態也非常適合用以獲得具有零偏移力的負剛性。當第二磁鐵及第三磁鐵為固定,第一磁鐵與光學元件的一部份一起移動以獲得光學元件的所需變形。 This configuration is also very suitable for obtaining negative rigidity with zero offset force. When the second magnet and the third magnet are fixed, the first magnet and a part of the optical element move together to obtain the required deformation of the optical element.
根據另一具體實施例,光學裝置包含一基底,其中磁鐵由緊固至光學元件的第一磁鐵以及緊固至基底的第二磁鐵所組成,其中第一磁鐵或第二磁鐵形成為一環形磁鐵且另一磁鐵可沿環形磁鐵的中心軸移動。 According to another specific embodiment, the optical device includes a substrate, wherein the magnet is composed of a first magnet fastened to the optical element and a second magnet fastened to the substrate, wherein the first magnet or the second magnet is formed as a ring magnet And the other magnet can move along the central axis of the ring magnet.
此具體實施例描述磁鐵的另一組態,以獲得具有零偏移力的負剛性。同樣地,第二磁鐵是固定的,且當光學元件變形時,第一磁鐵與光學元件的一部份一起移動。 This specific embodiment describes another configuration of the magnet to obtain negative rigidity with zero offset force. Similarly, the second magnet is fixed, and when the optical element deforms, the first magnet moves with a part of the optical element.
根據另一具體實施例,光學裝置包含一調整單元,用以調整補償單元的負剛性。 According to another embodiment, the optical device includes an adjustment unit for adjusting the negative rigidity of the compensation unit.
因為系統剛性的降低,光學裝置的共振模式(resonance mode)可能劣化。當致動器關閉或由於故障而不能提供適當的力時,這可能導致無法接收的動態性能。然而,這可藉由包含可開啟或關閉負剛性的切換機制來抵消。這在例如光學裝置或包含此一裝置的微影設備的傳輸期間也是有利的。一般在傳輸期間,共振頻率可能對光學裝置造成損害。現在包含調整單元將允許光學元件具有其(正常的)正剛性或至少實質正剛性,其將避免在傳輸等期間損害光學元件。另一方面,調整單元可甚至即時地調整負剛性,以在光學裝置的操作期間將所需的致動器力保持在最小。調整單元可組態以連續地調整負剛性。 Because of the decrease in the rigidity of the system, the resonance mode of the optical device may be degraded. This may result in unacceptable dynamic performance when the actuator is closed or cannot provide the proper force due to a malfunction. However, this can be counteracted by including a switching mechanism that can turn negative stiffness on or off. This is also advantageous during the transmission of, for example, an optical device or a lithography device containing such a device. Generally during transmission, the resonance frequency may cause damage to the optical device. The inclusion of the adjustment unit will now allow the optical element to have its (normal) positive rigidity or at least substantially positive rigidity, which will avoid damage to the optical element during transmission or the like. On the other hand, the adjustment unit can adjust the negative rigidity even instantaneously to keep the required actuator force to a minimum during the operation of the optical device. The adjustment unit can be configured to continuously adjust the negative rigidity.
根據另一具體實施例,調整單元組態用以使用至少一電永磁鐵(electro-permanent magnet)來預載至少一彈簧、調整第一磁鐵、第二磁 鐵及/或第三磁鐵的相對位置、調整在第一磁鐵、第二磁鐵及/或第三磁鐵之間耦合的一磁場、或調整第一磁鐵、第二磁鐵及/或第三磁鐵的磁場。 According to another embodiment, the adjustment unit configuration is used to use at least one electro-permanent magnet to preload at least one spring and adjust the first magnet and the second magnet. The relative position of the iron and/or the third magnet, adjusting a magnetic field coupled between the first magnet, the second magnet, and/or the third magnet, or adjusting the magnetic field of the first magnet, the second magnet, and/or the third magnet .
根據獲得負剛性的機制,調整負剛性的不同方式似乎是合適的。當使用彈簧作為負剛性的來源,可改變作用在彈簧上的預載以調整負剛性。預載可例如透過使用一氣壓缸(pneumatic cylinder)而實施。 Depending on the mechanism by which the negative stiffness is obtained, different ways of adjusting the negative stiffness seem to be appropriate. When using a spring as the source of negative stiffness, the preload acting on the spring can be changed to adjust the negative stiffness. Preloading can be implemented, for example, by using a pneumatic cylinder.
當使用磁鐵來獲得負剛性,可藉由調整其相對位置來改變磁鐵之間的排斥及吸引力,從而改變負剛性。為此可使用例如一固定螺絲或類似物。 When using magnets to obtain negative rigidity, the repulsion and attraction between the magnets can be changed by adjusting their relative positions, thereby changing the negative rigidity. For this, for example, a fixing screw or the like can be used.
此外,當使用磁鐵來獲得負剛性,磁鐵之間的磁場耦合可藉由例如使一動鐵(moving iron)用作為短路電路而改變。舉例來說,可使用馬蹄形動鐵。 In addition, when using magnets to obtain negative rigidity, the magnetic field coupling between the magnets can be changed by, for example, using a moving iron as a short circuit. For example, a horseshoe-shaped moving iron can be used.
更進一步,當使用磁鐵來獲得負剛性,磁鐵之間的吸引及排斥力可藉由調整相應磁鐵的磁場而改變。為此,可使用電永磁鐵。「電永磁鐵」目前定義為一磁性單元,其包含具有可調整永久磁化的至少一第一磁鐵以及用以調整至少一磁鐵之永久磁化的一裝置。 Furthermore, when magnets are used to obtain negative rigidity, the attractive and repulsive forces between magnets can be changed by adjusting the magnetic field of the corresponding magnets. For this purpose, electro-permanent magnets can be used. "Electro-permanent magnet" is currently defined as a magnetic unit, which includes at least one first magnet with adjustable permanent magnetization and a device for adjusting the permanent magnetization of the at least one magnet.
至少一磁鐵可例如由鐵磁或亞鐵磁材料所製成。 The at least one magnet may be made of ferromagnetic or ferrimagnetic material, for example.
「永久磁化」是指當用以調整永久磁化的裝置沒有產生磁場時,至少一磁鐵每年失去其磁化(例如以A/m來表示)不會多於5%、較佳為不會多於2%、更佳為不會多於0.5%。 "Permanent magnetization" means that when the device used to adjust the permanent magnetization does not generate a magnetic field, at least one magnet loses its magnetization (expressed in A/m for example) no more than 5%, preferably no more than 2 %, more preferably no more than 0.5%.
永久磁化是可調整的。這就是說,舉例而言,用於至少一磁鐵的永久磁化的裝置可在磁化的兩狀態之間切換。這兩個狀態可包含例如一去磁化狀態(磁化為零)以及一磁化狀態。在其他具體實施例中,這就是說用於永久磁化的裝置可在多於兩個、較佳為多於十個磁化狀態之間切換。切換也可連續地執行。用於永久磁化的裝置可形成為一線圈。藉由調整線圈中的電流,可調整用以磁化至少一磁鐵的外部磁場。 The permanent magnetization is adjustable. This means that, for example, the device for permanent magnetization of at least one magnet can be switched between two states of magnetization. These two states may include, for example, a demagnetization state (magnetization is zero) and a magnetization state. In other specific embodiments, this means that the device for permanent magnetization can be switched between more than two, preferably more than ten magnetization states. Switching can also be performed continuously. The device for permanent magnetization can be formed as a coil. By adjusting the current in the coil, the external magnetic field used to magnetize at least one magnet can be adjusted.
在一範例中,至少一磁鐵具有中等的矯頑磁場強度 (coercivity field strength)。「矯頑磁場強度」是指在至少一磁鐵的磁性材料的磁飽和之後完全地去磁化該材料所需的場強度。中等矯頑力材料為本領域中已知且例如包含鐵、鋁、鈷、銅及/或鎳。舉例來說,中等矯頑磁場強度對應10到300kA/m、較佳為40到200kA/m、更佳為50到160kA/m的磁場強度。特別地,中等矯頑力的材料為AlNiCo。AlNiCo是指鐵、鋁、鎳、銅和鈷的合金。 In one example, at least one magnet has a medium coercive field strength (coercivity field strength). The "coercive magnetic field strength" refers to the field strength required to completely demagnetize the magnetic material of at least one magnet after the magnetic material is saturated. Medium-coercivity materials are known in the art and include, for example, iron, aluminum, cobalt, copper, and/or nickel. For example, the medium coercive magnetic field strength corresponds to a magnetic field strength of 10 to 300 kA/m, preferably 40 to 200 kA/m, and more preferably 50 to 160 kA/m. In particular, the material with medium coercivity is AlNiCo. AlNiCo refers to an alloy of iron, aluminum, nickel, copper, and cobalt.
此外,磁性單元可包含另一磁鐵,其永久磁化不會被用以改變永久磁化的裝置改變。此特徵可藉由使用高矯頑力材料作為另一磁鐵(第二磁鐵)而獲得。第一磁鐵及第二磁鐵可共同產生所需的負剛性。在其他具體實施例中,第一磁鐵獨自產生所需的負剛性。 In addition, the magnetic unit may include another magnet whose permanent magnetization will not be changed by the device used to change the permanent magnetization. This feature can be obtained by using a high-coercivity material as another magnet (second magnet). The first magnet and the second magnet can jointly produce the required negative rigidity. In other specific embodiments, the first magnet alone generates the required negative rigidity.
藉由控制用以調整第一磁鐵的永久磁化的裝置,可適當地調整負剛性。 By controlling the device for adjusting the permanent magnetization of the first magnet, the negative rigidity can be adjusted appropriately.
根據另一具體實施例,光學元件在第一方向上變形時具有第一正剛性且在第二方向上變形時具有第二正剛性,其中致動器組態以在第一方向及第二方向上變形光學元件,且其中補償單元在第一方向上具有第一負剛性以在第一方向上至少部分地補償光學元件的正剛性,且在第二方向上具有第二負剛性以在第二方向上至少部分地補償光學元件的正剛性。 According to another embodiment, the optical element has a first positive rigidity when deformed in a first direction and a second positive rigidity when deformed in a second direction, wherein the actuator is configured to move in the first direction and the second direction. The upper deforming optical element, and wherein the compensation unit has a first negative rigidity in the first direction to at least partially compensate the positive rigidity of the optical element in the first direction, and has a second negative rigidity in the second direction to at least partially The positive rigidity of the optical element is at least partially compensated in the direction.
在此方式中,本發明的基本原理可應用至多軸系統。這類系統的反應可用一剛性矩陣來描述,其中非對角項描述軸之間的耦合。若系統明顯耦合,則前段所述的局部負剛性將不再足以補償所有的剛性力且需要建立等效的負剛性矩陣來補償正剛性矩陣。亦即,不僅對角(局部)的剛性需要被補償,且鄰近致動器之間的串擾也要被補償。根據幾何形狀,所產生的機械系統通常為稍微帶狀的剛性矩陣,其中鄰近的致動器將具有一些耦合剛性且遠離的致動器將具有(接近)零耦合剛性。以下的方程式1給出一典型的負剛性矩陣,其中kp為局部致動器負剛性且kc為自由度之間的耦 合剛性。δ1...δi給定在相應方向上的變形,且F1...Fi給定相應致動器所產生的負剛性力。 In this way, the basic principle of the present invention can be applied to a multi-axis system. The response of this type of system can be described by a rigid matrix, where off-diagonal terms describe the coupling between the axes. If the system is clearly coupled, the local negative rigidity described in the previous paragraph will no longer be sufficient to compensate for all the rigid forces and an equivalent negative rigidity matrix needs to be established to compensate the positive rigidity matrix. That is, not only the diagonal (local) rigidity needs to be compensated, but also the crosstalk between adjacent actuators needs to be compensated. Depending on the geometry, the resulting mechanical system is usually a slightly ribbon-like rigid matrix, where adjacent actuators will have some coupling rigidity and distant actuators will have (close to) zero coupling rigidity. The following equation 1 gives a typical negative stiffness matrix, where k p is the negative stiffness of the local actuator and k c is the coupling stiffness between degrees of freedom. δ 1 ... δ i gives the deformation in the corresponding direction, and F 1 ... F i gives the negative rigid force generated by the corresponding actuator.
舉例來說,具有方程式1中所述特性的負剛性矩陣可使用適當的磁鐵拓樸來獲得。 For example, a negative stiffness matrix with the characteristics described in Equation 1 can be obtained using an appropriate magnet topology.
根據另一具體實施例,致動器組態用以針對光學校正而變形光學元件。 According to another embodiment, the actuator is configured to deform the optical element for optical correction.
一般來說,光學校正可包含任何類型的影像誤差校正,特別是在重疊(overlay)及/或焦點校正(in focus correction)。 Generally speaking, the optical correction can include any type of image error correction, especially in overlay and/or in focus correction.
根據另一具體實施例,光學元件為一反射鏡、一透鏡、一光柵或一λ板(lambda plate)。 According to another specific embodiment, the optical element is a mirror, a lens, a grating, or a lambda plate.
λ板也稱作波片或阻片,即改變穿過它的光波的偏振狀態的光學裝置。 Lambda plates are also called wave plates or stop plates, which are optical devices that change the polarization state of light waves passing through it.
反射鏡可為平面或曲面。此外,反射鏡可為包含多個琢面之反射鏡的一琢面。 The reflector can be flat or curved. In addition, the mirror may be a facet of a mirror including multiple facets.
此外,提供了包含上述光學裝置的微影設備。 In addition, a lithography apparatus including the above-mentioned optical device is provided.
微影設備可為EUV或DUV微影設備。EUV代表「極紫外光」且表示曝光光的波長在0.1nm到30nm之間。DUV代表「深紫外光」且表示曝光光的波長在30nm到250nm之間。 The lithography equipment can be EUV or DUV lithography equipment. EUV stands for "Extreme Ultraviolet Light" and means that the wavelength of the exposure light is between 0.1nm and 30nm. DUV stands for "deep ultraviolet light" and means that the wavelength of the exposure light is between 30nm and 250nm.
光學裝置可整合至微影設備的一物鏡。物鏡可在晶圓的曝光期間浸潤於一液體中(浸潤式微影)。 The optical device can be integrated into an objective lens of the lithography equipment. The objective lens can be immersed in a liquid during the exposure of the wafer (immersion lithography).
將參照附隨的圖式對其他範例具體實施例作更詳細的解釋。 Other exemplary specific embodiments will be explained in more detail with reference to the accompanying drawings.
100A‧‧‧EUV微影設備 100A‧‧‧EUV lithography equipment
100B‧‧‧DUV微影設備 100B‧‧‧DUV lithography equipment
102‧‧‧照明系統 102‧‧‧Lighting System
104‧‧‧投射系統 104‧‧‧Projection System
106A‧‧‧EUV光源 106A‧‧‧EUV light source
106B‧‧‧DUV光源 106B‧‧‧DUV light source
108A‧‧‧EUV光 108A‧‧‧EUV light
108B‧‧‧DUV光 108B‧‧‧DUV light
110‧‧‧反射鏡 110‧‧‧Mirror
112‧‧‧反射鏡 112‧‧‧Mirror
114‧‧‧反射鏡 114‧‧‧Mirror
116‧‧‧反射鏡 116‧‧‧Mirror
118‧‧‧反射鏡 118‧‧‧Mirror
120‧‧‧光罩 120‧‧‧Mask
122‧‧‧晶圓 122‧‧‧wafer
124‧‧‧光學軸 124‧‧‧Optical axis
126‧‧‧反射鏡 126‧‧‧Mirror
132‧‧‧透鏡 132‧‧‧lens
134‧‧‧反射鏡 134‧‧‧Mirror
136‧‧‧液體介質 136‧‧‧Liquid medium
200‧‧‧光學裝置 200‧‧‧Optical device
202‧‧‧基底 202‧‧‧Base
204‧‧‧反射鏡 204‧‧‧Mirror
206‧‧‧孔 206‧‧‧Hole
208‧‧‧光學軸 208‧‧‧Optical axis
210‧‧‧前端面 210‧‧‧Front face
300‧‧‧支撐物 300‧‧‧Support
302‧‧‧支撐物 302‧‧‧Support
304‧‧‧後端面 304‧‧‧Back end
306‧‧‧致動器 306‧‧‧Actuator
308‧‧‧控制器 308‧‧‧controller
310‧‧‧補償單元 310‧‧‧Compensation Unit
310a-310b‧‧‧補償子單元 310a-310b‧‧‧Compensation subunit
500‧‧‧彈簧 500‧‧‧Spring
502‧‧‧氣壓缸 502‧‧‧Pneumatic cylinder
504‧‧‧側面 504‧‧‧Side
600‧‧‧第一磁鐵 600‧‧‧First magnet
600a-600c‧‧‧第一磁鐵 600a-600c‧‧‧First magnet
602‧‧‧連接 602‧‧‧Connect
602a-602c‧‧‧連接器 602a-602c‧‧‧Connector
604‧‧‧第二磁鐵 604‧‧‧Second magnet
604a-604c‧‧‧第二磁鐵 604a-604c‧‧‧Second magnet
606‧‧‧第三磁鐵 606‧‧‧The third magnet
606a-606c‧‧‧第三磁鐵 606a-606c‧‧‧Third magnet
608‧‧‧中心軸 608‧‧‧Central axis
610‧‧‧對稱軸 610‧‧‧Symmetry axis
700‧‧‧調整單元 700‧‧‧Adjustment unit
702‧‧‧控制器 702‧‧‧controller
704‧‧‧感測器 704‧‧‧Sensor
706‧‧‧電永磁鐵 706‧‧‧Electro permanent magnet
708‧‧‧第一電永磁鐵 708‧‧‧The first electro-permanent magnet
710‧‧‧線圈 710‧‧‧Coil
712‧‧‧第二電永磁鐵 712‧‧‧Second electropermanent magnet
714‧‧‧鐵心 714‧‧‧Iron Heart
F,F1,F2,F3‧‧‧力 F, F 1 , F 2 , F 3 ‧‧‧force
Fc‧‧‧預載力 F c ‧‧‧Preload force
FD‧‧‧動態力 F D ‧‧‧Dynamic force
Fn‧‧‧負剛性力 F n ‧‧‧Negative rigidity
Fp‧‧‧正剛性力 F p ‧‧‧positive rigidity
FQ‧‧‧靜態力 F Q ‧‧‧Static force
Fr‧‧‧合力 F r ‧‧‧Joint Force
kr‧‧‧得到的剛性 k r ‧‧‧obtained rigidity
kn‧‧‧負剛性 k n ‧‧‧Negative rigidity
kp‧‧‧正剛性 k p ‧‧‧positive rigidity
M1-M6‧‧‧反射鏡 M1-M6‧‧‧Mirror
δ,δ1,δ2,δ3‧‧‧方向 δ,δ 1 ,δ 2 ,δ 3 ‧‧‧ direction
圖1A顯示EUV微影設備的示意圖;圖1B顯示DUV微影設備的示意圖;圖2顯示整合至例如圖1A或1B之微影射設備的光學裝置的透視圖;圖3示意地顯示圖2中的區段III-III;圖3A顯示與圖3相關的力圖;圖4A顯示根據第一具體實施例的一圖式,其描述圖3之光學裝置的力對位移圖;圖4B根據第二具體實施例描述圖3之光學裝置的力對位移圖;圖5A-5C分別以示意側視圖描述使用機械補償系統以獲得負剛性的光學裝置;圖6A以示意側視圖顯示使用磁性補償系統以獲得負剛性的光學裝置;圖6B顯示圖6A之具體實施例的變化形式;圖7A-7D顯示不同的具體實施例,以獲得具有可調整之負剛性的光學裝置;以及圖8以示意側視圖顯示包含沿多個軸之負剛性補償的光學裝置。 Figure 1A shows a schematic diagram of EUV lithography equipment; Figure 1B shows a schematic diagram of DUV lithography equipment; Section III-III; Fig. 3A shows a force diagram related to Fig. 3; Fig. 4A shows a diagram according to the first embodiment, which describes the force versus displacement diagram of the optical device in Fig. 3; Fig. 4B is based on the second embodiment The example describes the force vs. displacement diagram of the optical device in Figure 3; Figures 5A-5C illustrate the use of mechanical compensation systems to obtain negative rigidity in schematic side views respectively; Figure 6A illustrates the use of magnetic compensation systems to obtain negative rigidity in schematic side views. Fig. 6B shows a variation of the specific embodiment of Fig. 6A; Figs. 7A-7D show different specific embodiments to obtain an optical device with adjustable negative rigidity; Optical device for compensation of negative rigidity of multiple axes.
在圖式中,除非另有說明,類似的元件符號表示類似或功能上等效的元件。 In the drawings, unless otherwise specified, similar element symbols indicate similar or functionally equivalent elements.
圖1A顯示EUV微影設備100A的示意圖,其包含照明系統
102及投射系統104(亦稱作「POB」)。EUV代表「極紫外光」且表示曝光光的波長在0.1nm到30nm之間。照明系統102及投射系統104整合至由抽真空裝置(圖未示)抽空的真空外罩中。真空外罩由一機械室(machinery room)(圖未示)包圍。機械室包含用以定位光學元件的裝置。此外,機械室可包含控制裝置及其他電子設備。
Figure 1A shows a schematic diagram of
EUV微影設備100A包含EUV光源106A。EUV光源106A可形成為電漿源或在EUV範圍的同步加速器發射光108A,例如波長在0.1nm到30nm之間的光。EUV光108A聚束於照明系統102內,且期望的操作波長將被濾出。EUV光108A在空氣中具有低透射率,這是照明系統102及投射系統104要抽真空的原因。
The
圖1A中所示的照明系統102具有例如五個反射鏡110、112、114、116、118。在通過照明系統102之後,EUV光108A被導引至光罩120。光罩120也組態為反射光學元件且可配置在系統102、104之外。此外,可使用在系統102、104任一者外部的反射鏡126將EUV光108A導向光罩120。光罩120包含一結構,藉由投射系統140將該結構的更小影像投射至晶圓122或類似物。
The
投射系統140可包含例如六個反射鏡M1-M6,用以將結構投射至晶圓122。投射系統104的反射鏡M1-M6的其中一部份可相對投射系統104的光學軸124對稱地配置。當然,EUV微影設備100A的反射鏡的數量並不限於圖1A中所示的數量。此外,反射鏡可為不同形狀,例如某些可形成為曲面反射鏡,而其他可形成為琢面反射鏡。
The projection system 140 may include, for example, six mirrors M1-M6 for projecting the structure to the
圖1B顯示DUV微影設備100B的示意圖,其亦包含照明系統102及投射系統104。DUV指「深紫外光(deep ultraviolet)」且表示曝光光的波長在30nm到250nm之間。如參照圖1A所解釋,照明系統102及投射系統104可配置於真空外罩及/或機械室中。
FIG. 1B shows a schematic diagram of a
DUV微影設備100B包含DUV光源108B。DUV光源108B可
組態為波長在例如為193nm的ArF準分子雷射發射光108B。
The
照明系統102將DUV光108B導引至光罩120上。光罩120組態為透射式光學元件且可分別配置於系統102、104之外。同樣地,光罩120具有一結構,藉由投射系統140將該結構的更小影像投射至晶圓122或類似物。
The
投射系統104可包含多個透鏡132及/或反射鏡134,用以將光罩120的結構投射至晶圓122。透鏡132及/或反射鏡134可相對投射系統104的光學軸124對稱地配置。同樣地,DUV微影設備100B的透鏡或反射鏡的數量並不限於圖1B所示之透鏡及反射鏡的數量。
The
最後的透鏡132及晶圓122之間的空隙可用折射率大於1的液體介質136來取代。舉例來說,可使用高純度的水作為液體介質。此設置稱作浸潤式微影,其特徵在於增強的光學微影解析度。
The gap between the
圖2以透視圖顯示光學裝置200,其包含支撐光學元件204的基底202,光學元件204可例如形成為一反射鏡。
FIG. 2 shows an
光學裝置200可整合至圖1A及圖1B中所示之微影設備的其中一者。光學元件204可例如對應至反射鏡M1至M6的其中一者(圖1A)或對應至透鏡或反射鏡132、134的其中一者(圖1B)。在其他具體實施例中(圖未示),光學元件204組態為光柵或λ板。
The
基底202可緊固至微影設備100A、100B的一固定結構,例如緊固至一力框(圖未示)。為此,基底202可配備有緊固孔206或類似者。基底202可包含矩形或任何其他適合的形狀。
The base 202 can be fastened to a fixing structure of the
反射鏡204(為便於理解,以下將以反射鏡作參考,但這不應解釋為僅限於反射鏡,而是可使用任何其他適合的光學元件)反射入射光108A、108B。反射鏡204的對應光學軸以元件符號208來表示。至少光108A、108B被反射的前端面210、或整個反射鏡204可為彎曲(如圖所示)或直的。
The reflecting mirror 204 (for ease of understanding, the following will take the reflecting mirror as a reference, but this should not be interpreted as being limited to the reflecting mirror, but any other suitable optical element can be used) to reflect the
圖3顯示圖2中的區段III-III。圖中繪示反射鏡204在未變形狀態(實線)及在變形狀態(點虛線)。反射鏡204顯示為在其未變形狀態下具有平
面形狀。然而,反射鏡204在其未變形狀態下可具有任何形狀,例如彎曲的形狀。
Figure 3 shows the section III-III in Figure 2. The figure shows the
反射鏡204可例如在兩個位置由例如支撐物300、302所支撐。支撐物300、302可在反射鏡204的後端面304支撐反射鏡204或其部分。在此簡單的支撐組態中,支撐物300可組態為允許反射鏡204的相對旋轉,但仍在垂直於光學軸208的方向中將反射鏡204固定地連接至基底202。另一方面,支撐物302允許反射鏡204的相對旋轉,並允許反射鏡204相對於光軸208的垂直移動。此處所使用的「垂直」可包含與準確垂直的偏差達10°、較佳為達5°、更佳為達1°。
The
然而,反射鏡204或其部分的任何其他類型的支撐是可能的。舉例來說,反射鏡204可在多於兩個位置處被支撐,例如五個、十個、二十個或更多位置。此外,支撐物可組態以在其連接至反射鏡204的位置處產生力或力矩或兩者。
However, any other type of support of the
此外,光學裝置200包含致動器306。致動器306組態以在圖3所示的兩狀態之間變形光學元件204(或其部分)。致動器306一方面緊固至反射鏡204,另一方面緊固至基底202或任何其他適當的參考物。致動器306可例如組態為勞侖茲式致動器,亦即包含音圈(圖未示)及磁鐵(圖未示)以在反射鏡204上產生一合力Fr(參考圖3A,其顯示關於圖3的力圖)以變形反射鏡204。力Fr所作用的方向係標示為δ。
In addition, the
原則上,可使用任何其他致動器(例如壓電致動器或氣動致動器)來取代勞侖茲致動器。然而,特別是當用於開迴路控制系統中時,使用勞侖茲致動器可提供可具成本效益的低複雜度系統。 In principle, any other actuators, such as piezoelectric actuators or pneumatic actuators, can be used instead of Lorentz actuators. However, especially when used in open-loop control systems, the use of Lorentz actuators can provide a cost-effective, low-complexity system.
當使用勞侖茲致動器時,磁鐵可緊固至反射鏡204(特別是緊固至其後側304),且音圈可緊固至基底202。音圈306緊固至反射鏡204且磁鐵緊固至基底202的其他配置也是可能的。
When a Lorentz actuator is used, the magnet can be fastened to the mirror 204 (especially to the
致動器306可由控制器308控制。控制器308可組態以控制致
動器306,以變形反射鏡204來提供光學校正。亦即,藉由變形反射鏡204,入射光108A、108B的角度將改變。光學校正可包含影像誤差校正,例如重疊或焦點校正。「影像」指投射至晶圓122上的影像(參考圖1A及1B)。
The
控制器308可組態以即時變形反射鏡204,例如在曝光晶圓122上的兩個不同晶粒之間或甚至在晶粒內(即在晶圓122上的單一晶粒的掃瞄期間)的時窗內。晶圓122上相應晶粒的掃描可例如以30Hz進行。因此,改變反射鏡204的變形的時窗可小於1/30秒。
The
在圖3的範例中,在方向δ上變形反射鏡204可藉由反射鏡204的平面外彎曲而獲得。這是由於致動器306在平行於光學軸208的方向δ上在兩個支撐物300、302之間的一位置作用在反射鏡204上。「平行」可包含與精確平行偏離達10°、較佳達5°、且更佳達1°。
In the example of FIG. 3, the deforming
當反射鏡204由在方向δ上作用的一力所變形時,此力一般來說將由兩個分力所組成。首先為變形反射鏡204本身所需的準靜態力FQ(參考圖3A)。此靜態力為反射鏡204的材料的E模量以及其幾何形狀的函數,因此對應反射鏡204的(正)剛性。另一方面,力將由加速反射鏡204的質量所需的動態力FD所形成。此動態力取決於反射鏡204的密度、幾何變形輪廓、及變形軌道(為時間函數)。為了降低致動器306變形反射鏡204所需耗費的合力Fr,反射鏡的正剛性與相應的負剛性成對。為此,光學裝置200包含一補償單元310,其在方向δ上具有負剛性以至少部分地補償反射鏡204的正剛性。
When the
圖3A顯示在致動器306及補償單元310的位置處作用在反射鏡204上的力的示意圖。當反射鏡204在方向δ上變形時,反射鏡的正剛性kp導致一正力Fp。這也示於圖4A中,其顯示力F對變形δ的圖式。另一方面,當反射鏡在與力Fp相反的方向δ上變形時,補償單元310的負剛性將導致一力Fn。所產生的力為力FQ,其為在方向δ上變形反射鏡204所需的靜態力。除了靜態力FQ之外,致動器306需施加動態力FD於反射鏡204上以將其加速。力
FQ及FD的總和等於由致動器306所施加的合力Fr。由於Fn及Fp遠大於FQ、FD及Fr,其在圖3A中並未依比例繪示而分別以虛線表示。
FIG. 3A shows a schematic diagram of the force acting on the
由於反射鏡204在方向δ上的變形量一般為小(例如在微米範圍內),且同時變形的時窗相當大(例如1/30秒)(參考前文中有關掃描軌跡的解釋),所需的動態力FD相較於靜態力FQ為小。此外,藉由適當的系統設計而將合力Fr(=FQ+FD)給定為遠小於由補償單元所產生的力Fn。顯然地,當產生晶粒或晶圓時,力Fp、Fn、FD可隨時間改變。然而,力一般將顯示為在單一晶粒或整體晶圓的製造上是循環的。已發現系統可設計使得當看單一週期時,負剛性力Fn具有一最大值,其比需由致動器306所產生之最大合力Fr大N倍,其中較佳為N>5、更佳為N>10、進一步更佳為N>50。
Since the amount of deformation of the
這類型的系統設計使致動器306具有低能量消耗。這轉而使相應的熱耗損為小,因而避免熱膨脹問題及相應的冷卻問題。
This type of system design enables the
為了進一步改善系統設計,「大」的力Fp及Fn可設計成與「小」的動態力FD相較變化很小。為此,動態力FD在一循環上的最大時間導數(參考前文的解釋)可比負剛性力Fn的最大時間導數大M倍,其中M較佳為大於1、更佳為大於2、且再更佳為大於10。 In order to further improve the system design, the "large" forces F p and F n can be designed to have a small change compared with the "small" dynamic forces F D. For this reason, the maximum time derivative of the dynamic force F D in a cycle (refer to the previous explanation) can be M times larger than the maximum time derivative of the negative rigid force F n , where M is preferably greater than 1, more preferably greater than 2, and More preferably, it is greater than 10.
為了進一步改善系統的能源效率,致動器306可設計以恢復反射鏡204中的動態能量。換言之,當反射鏡204需要減速,反射鏡204在致動器306上所作的功轉換為電能,其回到電能儲存器。因此,致動器306的熱耗損可進一步的降低。
In order to further improve the energy efficiency of the system, the
現在回到圖4A,可看出正剛性力Fp、負剛性力Fn及合力Fr分別取決於剛性kp(正剛性)、kn(負剛性)、kr(所得到的剛性)以及變形δ。較佳地,所得到的剛性kr以及相應的合力Fr係設計為正且不等於零。舉例來說,負剛性kn可等於正剛性kp的0.9到0.99倍。這將確保當致動器306未產生力時(例如當致動器306關閉(無電源)時,像是在光學裝置200或微影設備100A、100B的傳輸期間)或當存在致動器306的不可預見的故障時,將限定
反射鏡204在方向δ上的變形。藉由將所得到的剛性kr選擇為正,反射鏡204將回到其未變形狀態,而無致動器306的動作(致動器306關閉或故障)。
Now returning to Figure 4A, it can be seen that the positive rigid force F p , the negative rigid force F n and the resultant force F r depend on the rigidity k p (positive rigidity), k n (negative rigidity), and k r (the resulting rigidity), respectively And the deformation δ. Preferably, the obtained rigidity k r and the corresponding resultant force F r are designed to be positive and not equal to zero. For example, the negative rigidity k n may be equal to 0.9 to 0.99 times the positive rigidity k p . This will ensure that when the
圖4B根據光學裝置200的另一具體實施例顯示力對變形圖。在此具體實施例中,負剛性力Fn可開啟或關閉,如後文中參照圖7A至7D所作的進一步解釋。因此,當關閉負剛性kn,所產生的剛性將對應正剛性kp,其足夠大以避免例如在傳輸期間由於振動或其他移動而損壞反射鏡204。因此,在光學裝置200的正常操作期間(亦即在晶圓的製造期間)所產生的剛性kr可設計為比在圖4A所述之具體實施例中更小(或等於零)。舉例來說,在圖4B的具體實施例中,負剛性kn可設計為正剛性kp的0.99到0.999倍。
FIG. 4B shows a force versus deformation diagram according to another specific embodiment of the
範例:若反射鏡質量假設為1kg,在10ms的移動時間內移動超過1μm,則需要10mm/s2的加速度。相應的動態力FD等於10mN,其可由勞倫茲致動器在低於1mW的功率耗損下傳遞。 Example: If the mass of the mirror is assumed to be 1kg, and it moves more than 1μm in a moving time of 10ms, an acceleration of 10mm/s 2 is required. The corresponding dynamic force F D is equal to 10 mN, which can be transmitted by the Lorentz actuator with a power loss of less than 1 mW.
補償反射鏡正剛性kn所需的負剛性kp在105到106N/m的等級。針對1μm的偏移,這將因此需要1N的負剛性力Fn。這對應100倍的動態力FD。為了與動態力FD有相同的數量級,負剛性力Fn需非常的準確。較佳地,負剛性力可即時地調整,即在光學裝置200的操作期間動態地調整。調整負剛性的方式將在後文中參照圖7A至7D來解釋。
The negative rigidity k p required to compensate the positive rigidity k n of the mirror is in the order of 10 5 to 10 6 N/m. For an offset of 1 μm, this will therefore require a negative rigid force F n of 1 N. This corresponds to 100 times the dynamic force F D. In order to have the same order of magnitude as the dynamic force F D , the negative rigid force F n needs to be very accurate. Preferably, the negative rigidity can be adjusted instantly, that is, dynamically adjusted during the operation of the
現在,將參考圖5A至5C來解釋使用機械補償以獲得所需負剛性kn之光學裝置200的具體實施例。
Now, a specific embodiment of the
圖5A的補償單元310包含例如機械彈簧500(例如片簧或螺旋彈簧)及組態以預載彈簧500的預載單元502(例如氣壓缸)。作用在例如反射鏡204的側面504上的彈簧500較佳組態為相當的長。當反射鏡204變形時,長彈簧500確保約為恆定的一預載力Fc,因此此變形也將造成反射鏡204橫向地移動,即在垂直光學軸208的方向。除了使用氣壓缸502,彈簧500可能在其壓縮狀態附接至基底202,以產生力Fc。在其他具體實施例中,可例如藉由氣壓缸或使用磁鐵直接地(不使用機械彈簧)施加力Fc。
The
圖5A的反射鏡204在平面中(即與光學軸208成直角)以補償力Fc預載。力Fc趨向使反射鏡204彎曲,並因此將反射鏡204彎曲到平面外。此力Fc可例如藉由機械彈簧500施加。
The
因為反射鏡204為對稱,反射鏡204的一半可認為是簡單的懸臂,在其端部受到一力,如圖5B所示。
Because the
偏移由下式給出:
因此,反射鏡204的正剛性kp由下式給出:
在偏移δ處施加至懸臂的壓縮力Fc(預載)(參考圖5B及5C)將導致大小為Fc.δ的彎曲力矩。此力矩產生偏移δ'使得:
當δ=δ'(對應零剛性,亦當正剛性kp等於負剛性kn),所需的補償力Fc由下式給出:
因此,前文已顯示恆定的預載力Fc適用以提供負或接近負的剛性,其將補償反射鏡204的正剛性。舉例來說,可由預載的一長彈簧500提供接近恆定的補償力Fc。
Therefore, the foregoing has shown that a constant preload force F c is suitable to provide a negative or nearly negative rigidity, which will compensate the positive rigidity of the
圖6A及6B描述包含磁鐵之補償單元310的第一及第二具體實施例。
6A and 6B depict the first and second specific embodiments of the
圖6A的補償單元310包含緊固至反射鏡204的第一磁鐵600以產生負剛性力Fn。第一磁鐵600及反射鏡204之間的連接係標示為602。磁鐵600配置於靜止的第二及第三磁鐵604、606之間。為此,第二及第三磁鐵604、606可緊固至基底202。第一磁鐵600可在方向δ上機械地導引。磁鐵600、604、606可組態為塊磁鐵,且可具有與方向δ相同的極性(由「N」來表示北方、「S」來表示南方)。因此,當第一磁鐵600位於第二及第三磁鐵604、606的中間時,第一磁鐵600在反射鏡204產生上零偏移力。同樣地,當反射鏡204的變形在方向δ上增加時,力Fn也相應地增加。因此,產生負剛性kn。
The
在圖6B的範例中,補償單元310包含透過連接602而連接至反射鏡204的第一磁鐵600。此外,補償單元310包含組態為一環形磁鐵的第二磁鐵604。環形磁鐵604具有中心軸608。當反射鏡204在方向δ上變形時,第一磁鐵600例如被機械地導引以沿中心軸608移動。第一磁鐵600及第二磁鐵604沿軸608具有相反的極性。當第一磁鐵600沿軸608配置於第二磁鐵604的對稱軸610上時,第一磁鐵600在反射鏡204上產生零偏移力。隨著反射鏡204的變形在方向δ上增加,第一磁鐵600所產生的負剛性力Fn也將如此,因為第一磁鐵600偏離其在對稱軸610的位置。
In the example of FIG. 6B, the
圖7A到7D顯示調整單元700的四個不同的具體實施例。
7A to 7D show four different specific embodiments of the
在圖7A的範例中,調整單元具有一氣壓缸700,其組態以開啟或關閉。在「關閉」狀態中,氣壓缸700不會產生預載力Fc於彈簧500上。另一方面,控制器702可組態成基於對控制器702的輸入而控制預載力Fc(甚
至連續地)。舉例來說,可設置一感測器704,其感測需要校正的光學誤差。控制器702可接收來自感測器704的相應輸入信號並控制氣壓缸700產生預載力Fc,其將產生導致適當光學校正之反射鏡204的變形。
In the example of FIG. 7A, the adjustment unit has a
由控制器702設定所需的預載力Fc可藉由在緩慢變形移動期間量測例如(勞侖茲)致動器306的電流來執行。由於這是緩慢的,加速力可忽略不計,且勞侖茲力只是由於殘餘剛性kr。若Fr及δ皆量測,則可決定kr,且相應地調整Fc直到達到所需的kr值。
The required preload force F c set by the
圖7B至7D的具體實施例也可包含控制器702,且根據情況也可包含感測器704。它們僅在調整負剛性力Fn的方式上有所不同。
The specific embodiments of FIGS. 7B to 7D may also include a
在圖7B的具體實施例中,調整單元700可包含機械裝置(例如固定螺絲)以沿中心軸608將第二磁鐵604從初始位置P1移動到位置P2,其中第一磁鐵600產生一初始偏移力於反射鏡204上。舉例來說,除了固定螺絲或類似物,也可使用電磁裝置來調整第二磁鐵604的位置。
In the specific embodiment of FIG. 7B, the
在圖7C的具體實施例中,調整單元700組態以調整耦合於第一磁鐵600及第二磁鐵604之間的磁場。為此,調整單元700可包含例如U形的移動磁鐵,其垂直於中心軸608移動以改變耦合於磁鐵600、604之間的磁場。在位置P1,磁鐵600、604配置於移動磁鐵700內。因此,在磁鐵600、604之間有一最大場。在位置P2,移動磁鐵700移動到磁鐵600、604配置在移動磁鐵700外部的位置。因此,在磁鐵600、604之間沒有(額外的)場耦合。當磁鐵600隨著反射鏡204變形而沿中心軸608移動時,這改變了在第一磁鐵600及第二磁鐵604之間作用的力。
In the specific embodiment of FIG. 7C, the
在圖7D的具體實施例中,調整單元700包含電永磁鐵706。電永磁鐵706包含由中等矯頑力材料所形成的至少一第一磁鐵708以及組態以根據例如從控制器702(參考圖7A)所接收的輸入信號來改變磁鐵708之磁化的線圈710。此外,調整單元700可包含高度矯頑力材料所形成的第二磁鐵712,且可附加地或替代地包含一鐵心714以增加整體的場強度。磁鐵708
及磁鐵712(若有提供的話)形成圖6B所述的第二磁鐵604。藉由調整第一磁鐵708的磁化,可調整第二磁鐵604所產生的磁場,並可因此而調整負剛性Fn。
In the specific embodiment of FIG. 7D, the
圖8顯示具有多軸δ1、δ2、δ3的光學裝置200,其中變形可沿軸δ1、δ2、δ3而發生。反射鏡204透過例如三個連接器602a、602b、602c分別連接至第一磁鐵600a、600b、600c。第一磁鐵600a、600b、600c相應地配置於第二及第三磁鐵604a、604b、604c及606a、606b、606c之間。關聯於相應連接器602a、602b、602c的每一個第一、第二及第三磁鐵604a...606c形成補償子單元310a、310b、310c。補償子單元310a、310b、310c共同形成了補償單元310。
Fig. 8 shows an
圖8的補償單元310的負剛性由以下的負剛性矩陣來描述:
剛性矩陣應建立以不僅產生所需的對角(局部)剛性,且需藉由在鄰近磁鐵604a...606c之間產生適當的負串擾(negative crosstalk)來補償反射鏡204的串擾項。
The stiffness matrix should be established to not only produce the required diagonal (local) stiffness, but also to compensate the crosstalk term of the
雖然本發明已基於特定具體實施例進行描述,但可能有許多修改及變化且結果仍落入本發明的範疇內。意圖或應推斷沒有關於本文所揭露之特定具體實施例的限制。 Although the present invention has been described based on specific specific embodiments, there may be many modifications and changes and the results still fall within the scope of the present invention. It is intended or should be inferred that there is no limitation on the specific specific embodiments disclosed herein.
202‧‧‧基底 202‧‧‧Base
204‧‧‧反射鏡 204‧‧‧Mirror
208‧‧‧光學軸 208‧‧‧Optical axis
210‧‧‧前端面 210‧‧‧Front face
300‧‧‧支撐物 300‧‧‧Support
302‧‧‧支撐物 302‧‧‧Support
304‧‧‧後端面 304‧‧‧Back end
306‧‧‧致動器 306‧‧‧Actuator
308‧‧‧控制器 308‧‧‧controller
310‧‧‧補償單元 310‧‧‧Compensation Unit
δ‧‧‧方向 δ‧‧‧direction
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