TW201343296A

TW201343296A - Laser scribing system and method with extended depth affectation into a workpiece

Info

Publication number: TW201343296A
Application number: TW102109207A
Authority: TW
Inventors: Jeffrey P Sercel; Marco Mendes; Mathew Hannon; Michael Von Dadelszen
Original assignee: Ipg Microsystems Llc
Priority date: 2012-03-16
Filing date: 2013-03-15
Publication date: 2013-11-01
Also published as: EP2825344A4; JP2015519722A; CN104334312A; EP2825344A1; KR20140137437A; WO2013138802A1

Abstract

Systems and methods for laser scribing provide extended depth affectation into a substrate or workpiece by focusing a laser beam such that the beam passes into the workpiece using a waveguide, self-focusing effect to cause internal crystal damage along a channel extending into the workpiece. Different optical effects may be used to facilitate the waveguide, self-focusing effect, such as multi-photon absorption in the material of the workpiece, transparency of the material of the workpiece, and aberrations of the focused laser. The laser beam may have a wavelength, pulse duration, and pulse energy, for example, to provide transmission through the material and multi-photon absorption in the material. An aberrated, focused laser beam may also be used to provide a longitudinal spherical aberration range sufficient to extend the effective depth of field (DOF) into the workpiece.

Description

使一工件中具有延伸深度虛飾之雷射切割系統及方法 Laser cutting system and method for extending depth in a workpiece

【相關申請案之交叉申請】[Cross-application for related applications]

本申請案係於2010年12月7日提出申請之美國專利申請案第12/962,050號之一部分接續申請案，該美國專利申請案主張於2009年12月7日提出申請之美國臨時專利申請案第61/267,190號之權利，該美國專利申請案及該美國臨時專利申請案以引用方式併入本文中。 This application is a continuation-in-part application of U.S. Patent Application Serial No. 12/962,050, filed on Dec. 7, 2010, which is incorporated herein by reference. The right of the present application is hereby incorporated by reference.

本發明係關於雷射加工，更具體而言，係關於使一工件中具有延伸深度虛飾之雷射切割。 This invention relates to laser processing, and more particularly to laser cutting having an extended depth illusion in a workpiece.

雷射通常用於切割或劃刻一工件(例如一基板或半導體晶圓)。例如在半導體製造中，一雷射常常用於切割一半導體晶圓之製程，俾使由該半導體晶圓製成之各個器件(或晶粒)彼此分離。晶圓上之各晶粒係藉由隔道(street)而被隔開，且可使用雷射沿隔道切割該晶圓。可使用一雷射完全切斷晶圓，或不完全切斷晶圓並藉由在穿孔點處斷開晶圓而將晶圓之剩餘部分分開。例如當製造發光二極體(light emitting diode；LED)時，晶圓上之各個晶粒對應於LED。 Lasers are commonly used to cut or scribe a workpiece (such as a substrate or semiconductor wafer). For example, in semiconductor fabrication, a laser is often used to cut a semiconductor wafer to separate individual devices (or die) made from the semiconductor wafer. Each die on the wafer is separated by a street and the wafer can be cut along the via using a laser. The wafer can be completely cut using a laser, or the wafer can be completely cut and the remainder of the wafer separated by breaking the wafer at the point of perforation. For example, when a light emitting diode (LED) is fabricated, each die on the wafer corresponds to an LED.

隨著半導體器件之尺寸日益減小，可在單個晶圓上製成之此等器件之數目增多。每個晶圓之器件密度增大會增大產量並相似地降低製造每一器件之成本。為增大此密度，期望盡可能緊密地製造此等器件。半導體晶圓上之器件定位越緊密，各器件間之隔道便越窄。因此，雷射光束被精確地定位於更窄之隔道內且應在對器件造成最小損傷或不造成損傷之條件下切割晶圓。 As semiconductor devices are becoming smaller in size, the number of such devices that can be fabricated on a single wafer is increased. An increase in device density per wafer increases throughput and similarly reduces the cost of manufacturing each device. To increase this density, it is desirable to manufacture such devices as closely as possible. The tighter the device is positioned on the semiconductor wafer, the narrower the barrier between the devices. Thus, the laser beam is accurately positioned within the narrower channel and the wafer should be cut with minimal or no damage to the device.

根據一種技術，一雷射可被聚焦至基板或晶圓之一表面上以燒蝕材料並達成一局部切割。雷射切割可對一半導體晶圓執行，例如，對晶圓之上面形成有器件之正面執行(被稱為正面切割(front-side scribing；FSS))，或對晶圓之背面執行(被稱為背面切割(back-side scribing；BSS))。儘管該等技術有效，然而其亦具有缺點。該二製程常常會導致大量碎屑產生且常常需要進行塗覆及沖洗製程以除去或減少碎屑。背面切割常常使用一更寬之切口及更寬之熱影響區(heat affected zone；HAZ)，此會導致發熱，進而可造成外延損傷及光損失。 According to one technique, a laser can be focused onto one of the substrate or wafer The surface is ablated and a partial cut is achieved. Laser cutting can be performed on a semiconductor wafer, for example, on the front side of the wafer on which the device is formed (referred to as front-side scribing (FSS)), or on the back side of the wafer (called For back-side scribing (BSS). Although these techniques are effective, they also have disadvantages. This two process often results in a large amount of debris generation and often requires a coating and rinsing process to remove or reduce debris. Backside cutting often uses a wider slit and a wider heat affected zone (HAZ), which can cause heat generation, which can cause epitaxial damage and light loss.

根據另一種常常被稱為隱形切割(stealth scribing)之技術，可藉由一高數值孔徑(numerical aperture；NA)透鏡(例如，NA>0.8)將一雷射聚焦於一晶圓內部，以於材料內引起多光子吸收。高NA透鏡提供一非常短之工作距離及非常小之景深(depth of field；DOF)。此種製程亦具有若干缺點。具體而言，隱形切割可能會限制晶圓之厚度，可能難以在翹曲之晶圓上執行，且在較厚晶圓上執行時可能要慢得多，乃因可能需要若干遍才能達成分離。隱形切割亦在晶圓之表面上提供一相對較大之光點大小(spot size)，此可妨礙在各晶粒間之狹窄隔道中執行正面切割或要求每一晶圓上具有更少之晶粒。因無法在晶圓內部獲得所期望之焦點，隱形切割技術亦在加工具有DBR或金屬反射膜之晶圓時存在問題。隱形切割亦需要昂貴之透鏡及嚴格之焦點公差，且隱形切割設備通常具有更高之裝備成本及年度維護成本。 According to another technique, often referred to as stealth scribing, a laser can be focused on a wafer by a high numerical aperture (NA) lens (eg, NA > 0.8). Multiphoton absorption is caused within the material. The high NA lens provides a very short working distance and a very small depth of field (DOF). This process also has several drawbacks. In particular, invisible dicing may limit the thickness of the wafer, may be difficult to perform on warped wafers, and may be much slower when performed on thicker wafers, as it may take several passes to achieve separation. Invisible dicing also provides a relatively large spot size on the surface of the wafer, which can prevent frontal dicing in narrow channels between dies or require less crystal on each wafer. grain. Stealth cutting technology also has problems in processing wafers with DBR or metal reflective films because of the inability to achieve the desired focus inside the wafer. Invisible cutting also requires expensive lenses and tight focus tolerances, and invisible cutting equipment typically has higher equipment costs and annual maintenance costs.

100‧‧‧雷射加工系統 100‧‧‧Laser processing system

102‧‧‧工件 102‧‧‧Workpiece

104‧‧‧表面 104‧‧‧ Surface

106‧‧‧燒蝕區 106‧‧‧Ablative area

108‧‧‧內部位置 108‧‧‧Internal position

110‧‧‧雷射 110‧‧‧Laser

112‧‧‧原始雷射光束 112‧‧‧Original laser beam

114‧‧‧擴張光束 114‧‧‧Expanded beam

116‧‧‧聚焦雷射光束 116‧‧‧Focused laser beam

120‧‧‧光束遞送系統 120‧‧‧beam delivery system

122‧‧‧擴束器 122‧‧‧beam expander

124‧‧‧聚焦透鏡 124‧‧‧focus lens

202‧‧‧工件 202‧‧‧Workpiece

204‧‧‧表面 204‧‧‧ surface

212‧‧‧原始雷射光束 212‧‧‧Original laser beam

213‧‧‧光線 213‧‧‧Light

214‧‧‧擴張雷射光束 214‧‧‧Expanded laser beam

215‧‧‧光線 215‧‧‧Light

216‧‧‧聚焦雷射光束 216‧‧‧ Focused laser beam

222‧‧‧擴束器 222‧‧‧beam expander

223‧‧‧衍射受限區域 223‧‧‧Diffraction restricted area

224‧‧‧聚焦透鏡/透鏡 224‧‧‧focus lens/lens

226‧‧‧近軸焦平面 226‧‧‧ paraxial focal plane

228‧‧‧有效DOF 228‧‧‧effective DOF

δ_f‧‧‧焦點偏移量 δ _f ‧‧‧Focus offset

802‧‧‧藍寶石基板 802‧‧‧ sapphire substrate

805‧‧‧雷射區 805‧‧‧Laser area

806‧‧‧燒蝕孔 806‧‧‧ ablative holes

808‧‧‧延伸深度虛飾通道 808‧‧‧Extended depth imaginary channel

1000‧‧‧雷射加工系統 1000‧‧‧Laser processing system

1001‧‧‧平面 1001‧‧ plane

1002‧‧‧工件 1002‧‧‧Workpiece

1003‧‧‧一側 1003‧‧‧ side

1005‧‧‧相對側 1005‧‧‧ opposite side

1016‧‧‧聚焦雷射光束 1016‧‧‧ Focused laser beam

1020‧‧‧雷射光束遞送系統 1020‧‧•Laser beam delivery system

1030‧‧‧氣浮X-Y定位台/X-Y定位台 1030‧‧‧Air-floating X-Y positioning table/X-Y positioning table

1034‧‧‧工件支撐部 1034‧‧‧Workpiece support

1040‧‧‧相對側照相機 1040‧‧‧ opposite side camera

1044‧‧‧正面照相機 1044‧‧‧Front camera

1050‧‧‧運動控制系統 1050‧‧‧ Motion Control System

1101‧‧‧半導體晶圓 1101‧‧‧Semiconductor wafer

1102‧‧‧基板 1102‧‧‧Substrate

1103‧‧‧正面 1103‧‧‧ positive

1104‧‧‧層 1104‧‧ layer

1105‧‧‧背面 1105‧‧‧Back

1106‧‧‧燒蝕區 1106‧‧‧Ablative area

1107‧‧‧隔道 1107‧‧‧way

1108‧‧‧延伸深度虛飾 1108‧‧‧Extended depth illusion

1109‧‧‧晶粒區段/區段 1109‧‧‧Grain section/section

1116‧‧‧雷射光束 1116‧‧‧Laser beam

1140‧‧‧相對側照相機 1140‧‧‧ opposite side camera

1201‧‧‧半導體晶圓 1201‧‧‧Semiconductor Wafer

1203‧‧‧正面 1203‧‧‧ positive

1205‧‧‧背面 1205‧‧‧Back

1206a‧‧‧背面切割線 1206a‧‧‧Back cutting line

1206b‧‧‧正面切割線 1206b‧‧‧ front cutting line

1207‧‧‧隔道 1207‧‧‧way

1208‧‧‧延伸深度虛飾 1208‧‧‧Extended depth illusion

1209‧‧‧區段 Section 1209‧‧‧

1216‧‧‧雷射光束 1216‧‧‧Laser beam

1240‧‧‧相對側照相機 1240‧‧‧ opposite side camera

1244‧‧‧加工側照相機 1244‧‧‧Processing side camera

1300‧‧‧雷射加工系統 1300‧‧ ‧ laser processing system

1302‧‧‧工件 1302‧‧‧Workpiece

1304‧‧‧表面 1304‧‧‧ surface

1306‧‧‧燒蝕區 1306‧‧‧Ablative area

1308‧‧‧內部位置 1308‧‧‧Internal position

1310‧‧‧超快雷射 1310‧‧‧Super fast laser

1316‧‧‧直線光束 1316‧‧‧Linear beam

1320‧‧‧光束遞送系統 1320‧‧‧beam delivery system

1321‧‧‧原始雷射光束 1321‧‧‧Original laser beam

1322‧‧‧擴束器 1322‧‧‧beam expander

1323‧‧‧擴張光束 1323‧‧‧Expanded beam

1324‧‧‧聚焦透鏡 1324‧‧‧focus lens

1325‧‧‧橢圓形光束 1325‧‧‧Oval beam

1326a‧‧‧圓柱形平凹透鏡 1326a‧‧‧Cylindrical plano-concave lens

1326b‧‧‧圓柱形平凸透鏡 1326b‧‧‧Cylindrical plano-lens lens

1328‧‧‧反射器 1328‧‧‧ reflector

在結合附圖閱讀以下詳細說明之後，將更佳地理解本發明之該等及其他特徵及優點，在附圖中：第1圖係為根據本發明實施例使一工件中具有延伸深度虛飾之一雷射切割系統之一示意圖；第2圖係為根據本發明實施例之一聚焦透鏡之一示意圖，該聚焦透鏡用於聚焦一雷射光束且使球面像差位於一衍射受限區域之外；第3A圖係為一透鏡提供無球面像差之一近軸聚焦雷射光束之一示意圖；第3B圖係為一透鏡被過度充填而超出一衍射受限區域以提供一具有像差之聚焦雷射光束之一示意圖，該雷射光束具有足以將景深延伸進入一工件中之一縱向球面像差範圍以及一受限之橫向球面像差範圍；第3C圖係為一透鏡被過度充填而進一步超出一衍射受限區域以提供一具有像差之聚焦雷射光束之一示意圖，該雷射光束具有一更大縱向及橫向球面像差範圍；第4A圖至第4C圖係為一具有像差之聚焦雷射光束相對於一工件之一表面位於不同焦點偏移位置之示意圖；第5A圖至第5D圖係為一聚焦雷射光束以不同焦點偏移量及不同球面像差量自一具有60毫米(mm)焦距之三元透鏡進入250微米厚之藍寶石之示意圖；第6A圖至第6D圖係為一聚焦雷射光束以不同焦點偏移量及不同球面像差量自一具有54毫米焦距之二元透鏡進入250微米厚之藍寶石之示意圖；第7A圖至第7D圖係為一聚焦雷射光束以不同焦點偏移量及不同球面像差量自一具有25毫米焦距之三元透鏡進入120微米厚之藍寶石之示意圖；第8圖係為顯示一藍寶石基板之一表面之一照片，該表面具有一系列燒蝕孔，該等燒蝕孔係藉由根據本發明一實施例之一種方法而形成；第9圖係為顯示一藍寶石基板之一側之一照片，該側具有自燒蝕孔延伸之一系列延伸虛飾，該等延伸虛飾係藉由根據本發明一實施例之一種方法形成；第10A圖及第10B圖係為根據本發明一實施例具有一工件定位台之一雷射加工系統之示意圖，該工件定位台分別位於一對齊位置及雷射加工位置；第11圖係為根據本發明一實施例之背面切割之一側視示意圖，其中一雷射光束與一半導體晶圓上之隔道進行相對側對齊；第12A圖及第12B圖係為根據本發明一實施例之雙面切割之側視示意圖，其中一雷射光束與一較淺之背面劃痕進行相對側對齊；以及第13圖係為根據本發明另一實施例之一用於以延伸深度虛飾及一細長光束光點進行切割之雷射切割系統之一示意圖。 The above and other features and advantages of the present invention will become more apparent from the written description of the appended <RTI A schematic diagram of one of the laser cutting systems; and FIG. 2 is a schematic diagram of one of the focusing lenses for focusing a laser beam and locating the spherical aberration in a diffraction limited region according to an embodiment of the invention 3A is a schematic diagram of a lens providing a paraxially focused laser beam with a spherical aberration; FIG. 3B is a lens being overfilled beyond a diffraction limited region to provide an aberration A schematic diagram of a focused laser beam having a range of longitudinal spherical aberrations sufficient to extend depth of field into a workpiece and a limited range of lateral spherical aberration; FIG. 3C is a lens overfilled Further extending beyond a diffraction-limited region to provide a schematic image of a focused laser beam having aberrations having a larger range of longitudinal and lateral spherical aberration; FIGS. 4A through 4C are images having an image A schematic diagram of a poorly focused laser beam at a different focus offset position relative to a surface of a workpiece; 5A to 5D are a focused laser beam with different focus offsets and different spherical aberrations from one A schematic diagram of a ternary lens having a focal length of 60 millimeters (mm) into a sapphire of 250 micrometers thick; and FIGS. 6A to 6D are diagrams of a focused laser beam with different focus offsets and different spherical aberration amounts from one to 54 The binary lens of the rice focal length enters the schematic diagram of the sapphire of 250 micrometers thick; the 7A to 7D are the ternary of a focused laser beam with different focal offsets and different spherical aberrations from a focal length of 25 mm. A schematic view of a lens entering a 120 micrometer thick sapphire; Fig. 8 is a photograph showing a surface of a sapphire substrate having a series of ablation holes by an embodiment in accordance with the invention Formed by a method; FIG. 9 is a photograph showing one of the sides of a sapphire substrate, the side having a series of extended embossments extending from the ablation holes, the extended embossed by an embodiment according to the present invention One of the methods is formed; FIGS. 10A and 10B are schematic views of a laser processing system having a workpiece positioning table according to an embodiment of the present invention, the workpiece positioning table being respectively located at an aligned position and a laser processing position; Figure 11 is a side elevational view of a backside cut in accordance with an embodiment of the present invention, wherein a laser beam is aligned with the opposite side of a channel on a semiconductor wafer; Figures 12A and 12B are based on A side view of a double-sided cut of an embodiment of the invention in which a laser beam is aligned on the opposite side from a shallow back scratch; and FIG. 13 is an extension for use in accordance with another embodiment of the present invention. A schematic diagram of a laser cutting system with deep illusion and a slender beam spot for cutting.

根據本發明之實施例，用於雷射切割之系統及方法藉由以下方式在一基板或工件中提供延伸深度虛飾：聚焦一雷射光束，俾使該光束利用一波導自聚焦效應而進入該工件中，以沿一延伸至該工件中之通道造成內部晶體損傷。可利用不同之光學效應(例如，工件材料中之多光子吸收、工件材料之透明度、以及聚焦雷射光束之光學像差)來促進波導自聚焦效應。該雷射光束可具有一波長、脈波持續時間、及脈波能量，例如以至少部分地透射過材料並在材料中提供多光子吸收。亦可使用一具有像差之聚焦雷射光束來提供足以將有效景深(depth of field；DOF)延伸進入工件中之一縱向球面像差範圍。 In accordance with an embodiment of the present invention, a system and method for laser cutting provides an extended depth imaginary in a substrate or workpiece by focusing a laser beam and causing the beam to enter using a waveguide self-focusing effect. In the workpiece, internal crystal damage is caused by a passage extending into the workpiece. Different optical effects (eg, multiphoton absorption in the workpiece material, transparency of the workpiece material, and optical aberrations of the focused laser beam) can be utilized to promote the waveguide self-focusing effect. The laser beam can have a wavelength, pulse duration, and pulse energy, for example, to at least partially transmit the material and provide multiphoton absorption in the material. A focused laser beam with aberrations can also be used to provide a range of longitudinal spherical aberrations sufficient to extend the effective depth of field (DOF) into the workpiece.

產生延伸深度虛飾之雷射切割可用於切割工件(例如基板或半導體晶圓)，例如以使晶粒分離。根據一種應用，本文所述之雷射加工系統及方法可用於加工半導體晶圓，以分離用於形成發光二極體(light emitting diode；LED)之晶粒。產生延伸深度虛飾之雷射切割可用於對不同厚度之半導體晶圓進行背面切割及/或正面切割。可藉由選擇能使得至少部分地透射過材料並在材料中產生多光子吸收之雷射參數及光學參數而以延伸深度虛飾切割不同材料。具體而言，本文所述之方法可用於切割藍寶石、矽、玻璃、及其他能夠使一雷射光束至少部分地穿透材料並同時被充分吸收以造成晶體損傷之基板或材料。產生延伸深度虛飾之雷射切割亦可較佳地用於例如具有不透明塗層之工件上，乃因一初始燒蝕可切透該不透明塗層。 Laser cutting that produces extended depth illusions can be used to cut a workpiece, such as a substrate or a semiconductor wafer, for example to separate the dies. According to one application, the laser processing systems and methods described herein can be used to process semiconductor wafers to separate crystal grains for forming light emitting diodes (LEDs). Laser cutting that produces extended depth illusions can be used for backside cutting and/or frontal cutting of semiconductor wafers of different thicknesses. The different materials can be cut in an extended depth imaginary by selecting laser parameters and optical parameters that enable at least partial transmission of the material and multi-photon absorption in the material. In particular, the methods described herein can be used to cut sapphire, tantalum, glass, and other substrates or materials that enable a laser beam to at least partially penetrate the material while being sufficiently absorbed to cause crystal damage. A laser cut that produces an extended depth imaginary can also be preferably used, for example, on a workpiece having an opaque coating. The initial ablation can cut through the opaque coating.

本文所用術語「加工」係指任何使用雷射能量改變一工件之動作，且「切割」係指藉由在工件上掃描雷射而加工一工件之動作。加工可包含但不限於工件表面之材料燒蝕及/或工件內部之材料晶體損傷。切割可包含一系列燒蝕或晶體受損區域而無需連續的一行燒蝕或晶體損傷。本文所用術語「延伸深度虛飾」係指由於雷射能量以及工件內光子與材料之交互作用而沿一在工件內部延伸之通道發生之晶體損傷。 As used herein, the term "machining" refers to any action that uses a laser energy to change a workpiece, and "cutting" refers to the action of machining a workpiece by scanning a laser over the workpiece. Processing may include, but is not limited to, material ablation of the surface of the workpiece and/or damage to the material crystals within the workpiece. Cutting can include a series of ablated or crystal damaged regions without the need for a continuous row of ablation or crystal damage. As used herein, the term "extended depth illusion" refers to crystal damage occurring along a passage extending inside the workpiece due to the energy of the laser and the interaction of photons and material within the workpiece.

產生延伸深度虛飾之雷射切割可燒蝕材料之一外部並隨後將光束聚焦於內部以引起內部破裂或晶體損傷(即，延伸深度虛飾)，進而導致或促進切割或切塊(dicing)，例如以使晶圓晶粒分離。初始燒蝕可引起折射率改變，此會促進使雷射進入切口之波導或自聚焦效應，以在材料晶體結構內產生一會聚，進而有效地將高電場能聚焦至一點而使此點處發生晶體損傷。可將雷射參數最佳化以提供一清潔之燒蝕(即，具有最少碎屑)，進而促進自聚焦效應，以下將更詳細地闡述之。在其他實施例中，產生延伸深度虛飾之雷射切割亦可在不燒蝕工件表面之情況下執行。 A laser cut that produces an extended depth imaginary cut can be external to one of the ablative materials and then focus the beam inside to cause internal cracking or crystal damage (ie, extended depth illusion), thereby causing or facilitating cutting or dicing For example, to separate wafer grains. Initial ablation can cause a change in refractive index that promotes the waveguide or self-focusing effect of the laser into the slit to create a convergence within the crystal structure of the material, effectively focusing the high electric field energy to a point where it occurs. Crystal damage. The laser parameters can be optimized to provide a clean ablation (i.e., with minimal debris) to promote self-focusing effects, as will be explained in more detail below. In other embodiments, a laser cut that produces an extended depth illusion can also be performed without ablating the surface of the workpiece.

可藉由調整雷射參數(例如，波長、脈波持續時間、及脈波能量)以使得至少部分地透射過材料並提供足以打亂材料晶體結構之多光子吸收而達成延伸深度虛飾。具體而言，雷射光束可具有一能夠透射過工件材料之波長(例如，紅外光波長、綠色波長、或紫外光波長)，並可包含一具有超短脈波(例如，小於1奈秒)或短脈波(例如，小於200奈秒)之一脈波雷射光束，進而提供能夠引起多光子吸收之一峰值功率。因此，藉由使用一實質上透明之靶材及一高能量超快雷射，輻照度(irradiance)與延伸景深(DOF)之平衡便容許與靶材進行深體積範圍之交互作用。 The extended depth imaginary can be achieved by adjusting the laser parameters (eg, wavelength, pulse duration, and pulse energy) such that it is at least partially transmissive to the material and provides multiphoton absorption sufficient to disrupt the crystal structure of the material. In particular, the laser beam may have a wavelength that is transmissive to the workpiece material (eg, infrared, green, or ultraviolet wavelengths) and may include an ultrashort pulse (eg, less than 1 nanosecond) Or a short pulse (eg, less than 200 nanoseconds) one of the pulsed laser beams, thereby providing one of the peak powers that can cause multiphoton absorption. Thus, by using a substantially transparent target and a high energy ultrafast laser, the balance of irradiance and extended depth of field (DOF) allows for deep volume range interaction with the target.

雷射波長可處於紅外光(IR)範圍內並可為一次至五次諧波，更具體而言，可處於例如約1.04微米至1.06微米(IR)、514奈米至532奈米(綠光)、342奈米至355奈米(UV)、或261奈米至266奈米(UV)範圍內。在藍寶石中，例如可藉由處於UV 範圍內(例如，266奈米、343奈米、或355奈米)之一雷射波長而達成藉由延伸深度虛飾進行之切割。在矽中，可藉由處於IR範圍內例如長於1.2微米(此時矽開始透射)、更尤其係約1.5微米之一雷射波長而達成藉由延伸深度虛飾進行之切割。可使用處於可見範圍內之雷射波長以延伸深度虛飾來切割玻璃。如本文所揭露，藉由延伸深度虛飾進行之切割亦可藉由使用能夠透射過以下材料之雷射波長而用於具有帶隙(band gap)之半導體及介電材料，該等材料包含但不限於GaAs及其他III-V族材料、SiC、Si、GaN、AIN、及金剛石。 The laser wavelength may be in the infrared (IR) range and may be from one to five harmonics, more specifically, for example from about 1.04 micron to 1.06 micron (IR), from 514 nm to 532 nm (green light) ), from 342 nm to 355 nm (UV), or from 261 nm to 266 nm (UV). In sapphire, for example by UV Cutting by one of the laser wavelengths (for example, 266 nm, 343 nm, or 355 nm) is achieved by extending the depth illusion. In the crucible, the cutting by the extended depth imaginary can be achieved by a laser wavelength in the IR range, for example longer than 1.2 microns (where the enthalpy begins to transmit), more particularly about 1.5 microns. The glass can be cut using a laser wavelength in the visible range to extend the depth illusion. As disclosed herein, the dicing by extending the depth imaginary can also be used for semiconductor and dielectric materials having a band gap by using a laser wavelength that is transmissive to materials that include Not limited to GaAs and other III-V materials, SiC, Si, GaN, AIN, and diamond.

將一較長波長(例如，相較於習知之切割技術)與一較短脈波一同使用會使雷射能量尤其在高度透明材料(例如藍寶石)中具有更佳之耦合效率及吸收。脈波持續時間可短於熱擴散時間，進而引起材料之快速蒸發(即，以一直接固-氣相變(solid to vapor transition)達成蒸發性燒蝕)。為使某些材料之熔融最小化，例如脈波持續時間可為亞皮秒。當加工藍寶石時，例如可使用小於約10皮秒(ps)之超短脈波持續時間。在其他實例中，亦可使用大於1奈秒或甚至大於100奈秒之較長脈波持續時間(例如，在矽中可使用150奈秒至200奈秒之脈波)。 Using a longer wavelength (e.g., compared to conventional cutting techniques) with a shorter pulse wave results in better coupling efficiency and absorption of the laser energy, particularly in highly transparent materials such as sapphire. The pulse duration can be shorter than the thermal diffusion time, which in turn causes rapid evaporation of the material (ie, evaporative ablation with a solid to vapor transition). To minimize melting of certain materials, for example, the pulse duration can be sub-picoseconds. When processing sapphire, for example, an ultrashort pulse duration of less than about 10 picoseconds (ps) can be used. In other examples, longer pulse durations greater than 1 nanosecond or even greater than 100 nanoseconds may also be used (eg, 150 nanoseconds to 200 nanoseconds of pulse waves may be used in the sputum).

例如可使用超快雷射來產生皮秒或毫微微秒(femtosecond)之超短脈波。在某些實施例中，超快雷射可能夠產生具有不同波長(例如，約0.35微米、0.5微米、1微米、1.3微米、1.5微米、2微米或其間之任何增量)及不同超短脈波持續時間(例如，小於約10皮秒)之原始雷射光束。一超快雷射之一實例包含可購自TRUMPF之TruMicro系列5000皮秒雷射其中之一。雷射亦可以處於約10千赫(kHz)至1000千赫之一範圍內之重複率提供處於約1微焦耳(μJ)至1000微焦耳之一範圍內之一脈波能量。 For example, ultra-fast lasers can be used to generate ultra-short pulses of picosecond or femtosecond. In some embodiments, ultrafast lasers can be capable of producing different wavelengths (eg, about 0.35 micrometers, 0.5 micrometers, 1 micrometer, 1.3 micrometers, 1.5 micrometers, 2 micrometers, or any increment therebetween) and different ultrashort pulses. The original laser beam with a wave duration (eg, less than about 10 picoseconds). An example of an ultrafast laser includes one of the TruMicro series 5000 picosecond lasers available from TRUMPF. The laser can also provide a pulse energy in the range of about 1 microjoule (μJ) to 1000 microjoules at a repetition rate in the range of about 10 kilohertz (kHz) to 1000 kilohertz.

產生延伸深度虛飾之雷射切割通常使用工作距離較長之光學器件(例如，相較於用於隱形切割之高NA透鏡而使用一較低NA透鏡)。具有較長工作距離及較低NA之光學器件可包含例如NA小於0.8、更尤其係小於0.5或小於0.4之聚焦透鏡。產生延伸深度虛飾之雷射切割亦可引入球面像差，該球面像差具有足以將有效DOF延伸進入一工件中之一縱向球面像差範圍。相較於具有較高NA之透鏡，具有較長工作距離及較低NA之透鏡通常具有一更長之DOF。使用一引入球面像差之透鏡可進一步延伸有效DOF，俾使波導自聚焦效應在工件中增加一延伸區上之能量。 Laser cutting that produces extended depth illusions typically uses optics that have a long working distance (eg, a lower NA lens compared to a high NA lens for stealth dicing). Optics with longer working distance and lower NA can be packaged A focusing lens having, for example, an NA of less than 0.8, more particularly less than 0.5 or less than 0.4 is included. A laser cut that produces an extended depth illusion may also introduce a spherical aberration having a range of longitudinal spherical aberrations sufficient to extend the effective DOF into a workpiece. Lenses with longer working distances and lower NA typically have a longer DOF than lenses with higher NA. The use of a lens incorporating spherical aberration further extends the effective DOF so that the waveguide self-focusing effect adds energy to an extension in the workpiece.

如以下將更詳細地闡述，可藉由調整雷射參數(例如，波長、脈波持續時間、及脈波能量)、加工參數(例如，脈波間距)、及光學參數(例如，工作NA及焦深)來控制延伸深度虛飾之深度。 As will be explained in more detail below, by adjusting laser parameters (eg, wavelength, pulse duration, and pulse energy), processing parameters (eg, pulse spacing), and optical parameters (eg, working NA and Depth of focus) to control the depth of the extended depth illusion.

參見第1圖，用於藉由延伸深度虛飾進行雷射切割之一雷射加工系統100之一實施例可用於切割一工件102(例如一半導體晶圓之一藍寶石基板)。雷射加工系統100之此實施例包含一雷射110及一光束遞送系統120，雷射110用於產生一原始雷射光束，光束遞送系統120用於聚焦該雷射光束並將該聚焦雷射光束引導至工件102之一表面104。光束遞送系統120包含一擴束器(beam expander)122及一聚焦透鏡124，擴束器122用於擴張來自雷射110之一原始雷射光束112以形成一擴張光束114，聚焦透鏡124用於聚焦擴張光束114以提供一聚焦雷射光束116。光束遞送系統120亦可包含一自動聚焦系統(圖未示出)，然而可並非必須如此。 Referring to Fig. 1, an embodiment of a laser processing system 100 for laser cutting by extending depth imaginary can be used to cut a workpiece 102 (e.g., a sapphire substrate of a semiconductor wafer). This embodiment of the laser processing system 100 includes a laser 110 for generating an original laser beam and a beam delivery system 120 for focusing the laser beam and focusing the laser beam. The beam is directed to one of the surfaces 104 of the workpiece 102. The beam delivery system 120 includes a beam expander 122 and a focusing lens 124 for expanding an original laser beam 112 from the laser 110 to form an expanded beam 114, the focusing lens 124 being used The dilated beam 114 is focused to provide a focused laser beam 116. Beam delivery system 120 may also include an autofocus system (not shown), although this need not be the case.

在所示實施例中，雷射加工系統100對擴張雷射光束114進行聚焦，俾使聚焦雷射光束116之一能量密度足以在一燒蝕區106中燒蝕工件102之表面104，並使該光束利用波導自聚焦效應而穿透燒蝕區106並進入工件102中。因此，波導自聚焦效應將聚焦雷射光束116自燒蝕區106引導至在工件102內延伸之一內部位置108，在內部位置108處，由於震動、電場及/或壓力而造成晶體損傷。聚焦雷射光束116之每一脈波分別在工件102上形成一光束光點並利用波導自聚焦效應而延伸至工件102內，以在一延伸深度上提供高能量並在內部位置108處沿通道造成晶體損傷。儘管在每一位置處僅使用單個脈波之聚焦雷射光束116便可足夠，然而亦可使用一多脈波製程，其中後續脈波提供更深或更強之材料破裂。 In the illustrated embodiment, the laser processing system 100 focuses the dilated laser beam 114 such that one of the focused laser beams 116 has an energy density sufficient to ablate the surface 104 of the workpiece 102 in an ablation region 106 and The beam penetrates the ablated region 106 and enters the workpiece 102 using a waveguide self-focusing effect. Thus, the waveguide self-focusing effect directs the focused laser beam 116 from the ablation zone 106 to an internal location 108 extending within the workpiece 102 where the crystal is damaged by vibration, electric field and/or pressure. Each pulse of the focused laser beam 116 forms a beam spot on the workpiece 102 and extends into the workpiece 102 using a waveguide self-focusing effect to provide high energy over an extended depth and along the channel at an internal location 108. Causing crystal Body damage. Although it may be sufficient to use only a single pulsed focused laser beam 116 at each location, a multi-pulse process may be used in which subsequent pulses provide deeper or stronger material cracking.

可在工件102上掃描聚焦雷射光束116，俾藉由一系列雷射脈波而沿一切割線形成一系列燒蝕區106及晶體受損內部位置108(即，延伸虛飾)。例如可單遍或多遍地掃描雷射光束116，以達成各種深度及間距。例如，工件102可相對於聚焦雷射光束116移動，以形成該系列燒蝕區106及晶體受損內部位置108。燒蝕區106及晶體受損內部位置108可在此後有利於工件102沿切割線之分離。儘管所示實施例顯示在一具有LED晶粒之半導體晶圓上進行正面切割，然而雷射加工系統100亦可用於背面切割或雙面切割，以下將更詳細地闡述之。 The focused laser beam 116 can be scanned over the workpiece 102, and a series of ablation zones 106 and crystal damage internal locations 108 (i.e., extended embossments) are formed along a cutting line by a series of laser pulses. For example, the laser beam 116 can be scanned in a single pass or multiple passes to achieve various depths and spacings. For example, workpiece 102 can be moved relative to focused laser beam 116 to form a series of ablation zones 106 and crystal damage internal locations 108. The ablation zone 106 and the crystal damage internal location 108 may thereafter facilitate separation of the workpiece 102 along the cutting line. Although the illustrated embodiment shows front side cuts on a semiconductor wafer having LED dies, the laser processing system 100 can also be used for back side or double sided cut, as will be explained in more detail below.

端視材料類型而定，雷射110可能夠射出波長能夠至少部分地穿透工件102之材料之短脈波(例如，小於約200奈秒)或超短脈波(例如，小於約1奈秒)。根據藉由延伸深度虛飾切割藍寶石之一實例，雷射110係為一超快雷射，其射出一原始雷射光束，該原始雷射光束之波長處於UV範圍內(例如，約266奈米、343奈米、或355奈米)且具有小於約10皮秒之一脈波持續時間及約60微焦耳之一脈波能量。此種雷射提供一能夠穿透藍寶石之波長及一足夠高之峰值功率以損傷藍寶石內之內部位置處之晶體。可以一重複率操作雷射110，進而以一特定掃描速度達成一期望之切割。根據一加工藍寶石之實例，可以一約33.3千赫之重複率及處於一約70毫米/秒(mm/s)至90毫米/秒(mm/s)範圍之一掃描速度操作具有約60微焦耳之一脈波能量之UV雷射。在另一實例中，重複率可為約100千赫，且一掃描速度約為100毫米/秒至300毫米/秒。在其他實施例中，可以一減小之脈波能量(例如約40微焦耳)及一較高重複率(例如，約200千赫)使用一較低功率雷射(例如，約8瓦(W))。 Depending on the type of material, the laser 110 can be capable of emitting short pulses (eg, less than about 200 nanoseconds) or ultrashort pulses (eg, less than about 1 nanosecond) that are at least partially transparent to the material of the workpiece 102. ). According to one example of cutting sapphire by extending the depth imaginary, the laser 110 is an ultra-fast laser that emits an original laser beam having a wavelength in the UV range (eg, about 266 nm) , 343 nm, or 355 nm) and have a pulse duration of less than about 10 picoseconds and a pulse energy of about 60 microjoules. Such a laser provides a wavelength that can penetrate the sapphire and a peak power that is high enough to damage the crystal at the internal location within the sapphire. The laser 110 can be operated at a repetition rate to achieve a desired cut at a particular scan speed. According to an example of a processed sapphire, it can operate at a repetition rate of about 33.3 kHz and at a scanning speed of about one of a range of about 70 mm/sec (mm/s) to 90 mm/sec (mm/s) with about 60 microjoules. A UV laser with pulse energy. In another example, the repetition rate can be about 100 kHz and a scan speed is about 100 mm/sec to 300 mm/sec. In other embodiments, a lower power laser (eg, about 8 watts (W) can be used with a reduced pulse energy (eg, about 40 microjoules) and a higher repetition rate (eg, about 200 kilohertz). )).

擴束器122可係為一2×擴束望遠鏡(expanding telescope)，且聚焦透鏡124可係為一60毫米之三元透鏡以用於以一約400微米(μm)之焦深(focal depth)及一約3微米之所期望切口寬度(kerf width)達成一有效聚焦性能(focusability)。擴束器122可係為例如一擴束望遠鏡，該擴束望遠鏡包含一未經塗覆之負透鏡(例如，f=-100毫米)與一正透鏡(例如，f=200毫米)之組合。聚焦透鏡124可具有一小於0.8、更尤其係小於0.5或小於0.4之NA，此會提供一較長之工作距離及一較長之DOF。聚焦透鏡124亦可引入球面像差以提供一具有像差之聚焦雷射光束116，具有像差之聚焦雷射光束116具有一縱向球面像差範圍，該縱向球面像差範圍足以將有效DOF進一步延伸進入工件102中，以下將更詳細地闡述之。 The beam expander 122 can be a 2×expanding telescope, and the focusing lens 124 can be a 60 mm ternary lens for A focal depth of about 400 microns (μm) and a desired kerf width of about 3 microns achieve an effective focusability. The beam expander 122 can be, for example, a beam expander telescope comprising a combination of an uncoated negative lens (e.g., f = -100 mm) and a positive lens (e.g., f = 200 mm). Focusing lens 124 can have an NA of less than 0.8, more specifically less than 0.5 or less than 0.4, which provides a longer working distance and a longer DOF. The focusing lens 124 can also introduce spherical aberration to provide a focused laser beam 116 having aberrations, and the focused laser beam 116 having aberrations has a range of longitudinal spherical aberrations sufficient to further effective DOF Extending into the workpiece 102 will be explained in more detail below.

聚焦雷射光束與超短脈波或短脈波之組合會使增強之聚焦性能(具有較低之NA光學器件)在工件102之內部位置108處造成晶體損傷、同時使工件表面104上之被移除材料(例如，碎屑)之量最小化。雷射110及光束遞送系統120可配置有雷射加工參數(例如，波長、脈波持續時間、脈波能量、峰值功率、重複率、掃描速度、及光束長度及寬度)，該等雷射加工參數能夠達成針對欲切割材料之表面燒蝕及自聚焦效應以及達成期望之切口寬度。 The combination of a focused laser beam with an ultrashort pulse or a short pulse causes enhanced focus performance (with lower NA optics) to cause crystal damage at the internal location 108 of the workpiece 102 while simultaneously causing the workpiece surface 104 to be The amount of material removed (eg, debris) is minimized. Laser 110 and beam delivery system 120 may be configured with laser processing parameters (eg, wavelength, pulse duration, pulse energy, peak power, repetition rate, scan speed, and beam length and width), such laser processing The parameters enable surface ablation and self-focusing effects on the material to be cut and the desired slit width.

如第2圖更詳細地顯示，可藉由利用一聚焦透鏡224之透鏡像差延伸一具有像差之聚焦雷射光束216之有效DOF，來促進延伸深度虛飾。透鏡像差係為光線穿過一透鏡後相對於一理想路徑之偏差，該理想路徑係藉由近軸光學器件來預測。具體而言，球面像差係由光線穿過一透鏡後相對於透鏡光軸更遠之偏差產生。 As shown in more detail in FIG. 2, the extended depth imaginary can be promoted by extending the effective DOF of a focused laser beam 216 having aberrations using the lens aberration of a focusing lens 224. Lens aberration is the deviation of light from a perfect path after passing through a lens, which is predicted by the paraxial optics. In particular, spherical aberration is produced by the deviation of light passing through a lens further from the optical axis of the lens.

在此實施例中，聚焦透鏡224之一部分通常包含一衍射受限區域223，衍射受限區域223會提供實質上無像差(即，衍射對效能之影響超過像差對效能之影響)之衍射受限效能。在衍射受限區域223內照射透鏡224的一雷射光束214之光線213聚焦於近軸焦平面226處，進而在聚焦雷射光束216之此區域內產生一具有高解析度之聚焦光束光點。在衍射受限區域223外，聚焦透鏡224將球面像差引入至具有像差之聚焦雷射光束216中。在衍射受限區域223外照射透鏡224之光線215偏離近軸焦點並被聚焦(即，越過透鏡224之光軸)於近軸焦平面226後方之延伸焦點處。因此，球面像差會有效地使具有像差之聚焦雷射光束216之焦點自近軸焦點連續地延伸。 In this embodiment, a portion of the focusing lens 224 typically includes a diffraction limited region 223 that provides diffraction substantially free of aberrations (i.e., diffraction effects over performance that exceed the effects of aberrations on performance). Limited performance. The ray 213 of a laser beam 214 that illuminates the lens 224 within the diffraction limited region 223 is focused at the paraxial focal plane 226, thereby producing a high resolution focused beam spot in this region of the focused laser beam 216. . Outside the diffraction limited region 223, Focusing lens 224 introduces spherical aberration into the focused laser beam 216 with aberrations. The ray 215 that illuminates the lens 224 outside the diffraction limited region 223 is offset from the paraxial focus and is focused (ie, across the optical axis of the lens 224) at an extended focus behind the paraxial focal plane 226. Therefore, the spherical aberration effectively effectively extends the focus of the focused laser beam 216 having aberrations from the paraxial focus.

具有像差之光線215之焦點沿透鏡224之光軸延伸超過近軸焦平面226之距離係為縱向球面像差(longitudinal spherical aberration；LSA)範圍，且具有像差之光線215沿近軸焦平面226延伸之距離係為橫向球面像差(transverse spherical aberration；TSA)範圍。LSA範圍使聚焦雷射光束216之有效DOF 228延伸超過近軸焦平面226並有利於在一工件中產生延伸深度虛飾，以下將更詳細地闡述之。 The distance of the focus of the ray 215 having aberrations extending along the optical axis of the lens 224 beyond the paraxial focal plane 226 is a longitudinal spherical aberration (LSA) range, and the ray 215 having aberrations is along the paraxial focal plane. The distance extended by 226 is the transverse spherical aberration (TSA) range. The LSA range extends the effective DOF 228 of the focused laser beam 216 beyond the paraxial focal plane 226 and facilitates the creation of extended depth artifacts in a workpiece, as will be explained in more detail below.

因此，本發明之各實施例以與習知知識相反之方式利用一聚焦透鏡之瑕疵。在用於雷射切割之透鏡系統中，常常期望避免或校正透鏡像差來提供一聚焦良好之光束光點。然而，根據本發明之實施例，則有意地利用透鏡像差形成能夠延伸DOF之一光學效應，以藉由延伸深度虛飾而切割一工件。此外，如本文所述，用於藉由延伸深度虛飾進行雷射切割之透鏡可較隱形切割所需之高NA透鏡更廉價。 Thus, embodiments of the present invention utilize a focus lens in a manner contrary to conventional knowledge. In lens systems for laser cutting, it is often desirable to avoid or correct lens aberrations to provide a well focused beam spot. However, in accordance with an embodiment of the present invention, lens aberrations are intentionally utilized to form an optical effect capable of extending the DOF to cut a workpiece by extending the depth smear. Moreover, as described herein, a lens for laser cutting by extending depth imaginary can be less expensive than a high NA lens required for stealth cutting.

聚焦透鏡224可包含多元透鏡(例如二元透鏡或三元透鏡)，該多元透鏡在衍射受限區域223內而非在透鏡224之整個孔徑上校正像差。聚焦透鏡224亦可提供一相對長之工作距離以及小於約0.8、更尤其係小於約0.5或小於約0.4之低NA。不同之基板材料及厚度可具有用於藉由延伸深度虛飾進行切割之一不同最佳參數組合，包含波長、脈波持續時間、工作NA、縱向球面像差範圍、及散焦。因此，透鏡之準確光學參數將取決於欲被切割之材料類型。 Focusing lens 224 may comprise a multi-element lens (eg, a binary lens or a ternary lens) that corrects aberrations within diffraction-limited region 223 rather than across the entire aperture of lens 224. Focusing lens 224 can also provide a relatively long working distance and a low NA of less than about 0.8, more specifically less than about 0.5 or less than about 0.4. Different substrate materials and thicknesses may have different optimal parameter combinations for cutting by extending the depth imaginary, including wavelength, pulse duration, working NA, longitudinal spherical aberration range, and defocus. Therefore, the exact optical parameters of the lens will depend on the type of material being cut.

如第3A至第3C圖所示，聚焦透鏡224可被設計及/或照射以引入一足以延伸有效DOF之縱向球面像差範圍、同時限制橫向球面像差範圍。舉例而言，透鏡224之工作或運作NA(或 F#)可經選擇以獲得將在一工件202內提供期望之延伸虛飾之縱向球面像差範圍、同時限制橫向球面像差範圍，俾使工件202之一表面204上之聚焦光束光點大小不會過大。工件表面204上之期望光束光點大小取決於具體應用，且對於切割半導體晶圓及晶粒分離而言可小於約20微米。 As shown in Figures 3A through 3C, the focusing lens 224 can be designed and/or illuminated to introduce a range of longitudinal spherical aberrations sufficient to extend the effective DOF while limiting the range of lateral spherical aberration. For example, the operation or operation of the lens 224 is NA (or F#) may be selected to provide a range of longitudinal spherical aberrations that will provide a desired extended imaginary within a workpiece 202 while limiting the range of lateral spherical aberration such that the spot beam spot size on one of the surfaces 204 of the workpiece 202 is not It will be too big. The desired beam spot size on the workpiece surface 204 depends on the particular application and can be less than about 20 microns for dicing the semiconductor wafer and grain separation.

在此實施例中，可藉由以下方式調整透鏡224之工作或運作NA：使用一擴束器222擴張一原始雷射光束212，以產生一擴張雷射光束214，擴張雷射光束214照射透鏡224之通光孔徑(clear aperture)之一可變部分。當擴張雷射光束214僅在衍射受限區域223內照射透鏡224之孔徑時，如第3A圖所示，聚焦光束216僅包含聚焦至近軸焦平面之近軸光線，該近軸焦平面顯示於工件202之表面204上。此不會提供使有效DOF延伸進入工件202內之一縱向球面像差範圍來提供延伸深度虛飾。 In this embodiment, the operation or operation NA of the lens 224 can be adjusted by expanding a raw laser beam 212 using a beam expander 222 to produce a dilated laser beam 214 that dilates the laser beam 214 to illuminate the lens. One of the variable apertures of the 224 clear aperture. When the dilated laser beam 214 illuminates the aperture of the lens 224 only within the diffraction limited region 223, as shown in FIG. 3A, the focused beam 216 includes only paraxial rays that are focused to the paraxial focal plane, which is shown in On the surface 204 of the workpiece 202. This does not provide for extending the depth of the effective DOF into one of the longitudinal spherical aberration ranges within the workpiece 202 to provide an extended depth illusion.

當擴張雷射光束214剛剛超出衍射受限區域223而照射透鏡224之孔徑時，如第3B圖所示，聚焦光束216亦包含具有像差之光線，該等光線以能夠將DOF 228延伸進入工件202中之一縱向球面像差範圍聚焦於近軸焦平面之外。因當透鏡於近處工作而衍射不十分受限時縱向球面像差佔優勢，故聚焦光束216之具有像差之光線之橫向球面像差範圍可受限制。因此，縱向球面像差範圍會延伸DOF並同時仍保持橫向光點大小處於控制之中。 When the expanded laser beam 214 just illuminates the aperture of the lens 224 beyond the diffraction limited region 223, as shown in FIG. 3B, the focused beam 216 also includes light having aberrations that are capable of extending the DOF 228 into the workpiece. One of the longitudinal spherical aberration ranges in 202 is focused outside of the paraxial focal plane. Since the longitudinal spherical aberration is dominant when the diffraction is not very limited when the lens is working in the vicinity, the range of the lateral spherical aberration of the light having the aberration of the focused beam 216 can be limited. Therefore, the longitudinal spherical aberration range extends the DOF while still maintaining the lateral spot size under control.

當擴張雷射光束214照射透鏡224之整個孔徑時，如第3C圖所示，聚焦光束216包含具有像差之光線，該等具有像差之光線進一步延伸橫向球面像差範圍並進一步增大工件202之表面204上之光束光點大小。在此實例中，增大之橫向球面像差範圍可使縱向球面像差所提供之延伸DOF效應失效。 When the expanded laser beam 214 illuminates the entire aperture of the lens 224, as shown in FIG. 3C, the focused beam 216 contains light having aberrations that further extend the lateral spherical aberration range and further increase the workpiece. The beam spot size on surface 204 of 202. In this example, the increased range of lateral spherical aberration can invalidate the extended DOF effect provided by the longitudinal spherical aberration.

因此，可以一工作NA照射透鏡224，俾使縱向球面像差範圍足以將DOF延伸進入工件內，以產生期望之延伸深度虛飾、並同時限制橫向球面像差範圍。可於透鏡224處逐漸增大光束大小(例如，增大工作NA)，直至找到在工件202之材料內部產生延伸深度虛飾之最佳大小為止。限制橫向球面相差範圍能夠使工件表面上之光束光點大小變小、雷射區變小、且燒蝕區變小，同時仍能夠達成一足以延伸有效DOF之縱向球面像差範圍。在一實施例中，可充分地限制橫向球面像差範圍，以產生小於約20微米、更尤其係10微米至20微米之一雷射區以及小於約10微米、更尤其係約5微米之一燒蝕區。 Thus, the lens 224 can be illuminated by a working NA such that the longitudinal spherical aberration range is sufficient to extend the DOF into the workpiece to create the desired extended depth illusion while limiting the range of lateral spherical aberration. The beam size can be gradually increased at lens 224 (eg, increasing the working NA) until it is found inside the material of workpiece 202 Produce the best size for the extended depth illusion. Limiting the lateral spherical phase difference range enables the beam spot size on the surface of the workpiece to be reduced, the laser region to be smaller, and the ablation region to be smaller, while still achieving a range of longitudinal spherical aberration sufficient to extend the effective DOF. In one embodiment, the range of lateral spherical aberration can be substantially limited to produce one of less than about 20 microns, more particularly one to 10 microns to 20 microns, and less than about 10 microns, more specifically about 5 microns. Ablation zone.

對於一給定材料、波長、及脈波持續時間，最佳之NA及脈波能量將取決於材料厚度。對於薄的材料(例如，90微米至110微米之藍寶石)，可藉由一約0.15至0.2之工作NA以及處於一約10微焦耳至約50微焦耳範圍之脈波能量達成一期望之延伸深度虛飾深度。在使用一具有25毫米焦距及一18毫米通光孔徑之三元透鏡時，例如可藉由照射該25毫米三元透鏡之18毫米孔徑之約8毫米來達成具有一縱向球面像差範圍之一適宜光點大小，該縱向球面像差範圍足以在一90微米至110微米之材料厚度中達成延伸深度虛飾。為藉由一皮秒355奈米雷射來加工薄的藍寶石，例如可以約0.16 NA操作一具有25毫米焦距之三元透鏡，以達成一期望深度之延伸深度虛飾。在此實例中，根據一Zemax分析，縱向像差係數約為0.0133，且橫向像差係數約為0.0024。 For a given material, wavelength, and pulse duration, the optimum NA and pulse energy will depend on the material thickness. For thin materials (eg, sapphire from 90 microns to 110 microns), a desired depth of extension can be achieved by a working NA of about 0.15 to 0.2 and a pulse wave energy in the range of about 10 microjoules to about 50 microjoules. Faux depth. When a ternary lens having a focal length of 25 mm and an aperture of 18 mm is used, for example, one of a range of longitudinal spherical aberration can be achieved by irradiating about 8 mm of the 18 mm aperture of the 25 mm ternary lens. Suitable for the spot size, the longitudinal spherical aberration range is sufficient to achieve an extended depth illusion in a material thickness of 90 microns to 110 microns. To process a thin sapphire by a picosecond 355 nm laser, for example, a ternary lens with a 25 mm focal length can be operated at about 0.16 NA to achieve an extended depth imaginary of a desired depth. In this example, according to a Zemax analysis, the longitudinal aberration coefficient is about 0.0133, and the lateral aberration coefficient is about 0.0024.

對於較厚之材料(例如，250微米至500微米之藍寶石)，可藉由一約0.05至0.1之較低工作NA以及處於一約30微焦耳至70微焦耳範圍之一較高脈波能量來達成與該較厚材料相匹配之一期望延伸深度虛飾。為藉由一皮秒355奈米雷射來加工厚的藍寶石，可以約0.07NA操作一具有60毫米焦距之三元透鏡，以達成一期望深度之延伸深度虛飾。脈波能量可根據脈波間距而更高或更低，以達成一期望之深度。舉例而言，一較低之脈波能量可與一較短之脈波間距一起使用，而一較長之脈波間距可需要一較高之脈波能量。 For thicker materials (eg, sapphire from 250 microns to 500 microns), a lower pulsed energy of about 0.05 to 0.1 and a higher pulse energy of about 30 to 61 microjoules can be used. A desired extended depth illusion is achieved that matches the thicker material. To process a thick sapphire by a picosecond 355 nm laser, a ternary lens with a focal length of 60 mm can be operated at about 0.07 NA to achieve an extended depth illusion of a desired depth. The pulse energy can be higher or lower depending on the pulse spacing to achieve a desired depth. For example, a lower pulse energy can be used with a shorter pulse spacing, and a longer pulse spacing can require a higher pulse energy.

亦可使用其他技術來減小或消除過大之橫向球面像差。舉例而言，可將一光圈放置於透鏡224前方，以限制進入透鏡224中之最大光束直徑214，藉此限制最大NA。 Other techniques can also be used to reduce or eliminate excessive lateral spherical aberration. For example, an aperture can be placed in front of the lens 224 to limit penetration. The maximum beam diameter 214 in mirror 224, thereby limiting the maximum NA.

如上所述，可利用不同之雷射參數及光學器件藉由各種深度之延伸深度虛飾來切割不同之材料。在藍寶石中，例如一具有25毫米焦距之三元透鏡與一超快UV雷射一起可達成超過100微米深之延伸深度虛飾。在矽中，藉由一更長之透鏡以及具有更高功率之IR雷射，可達成一更深之延伸深度虛飾(例如，300微米)。 As noted above, different laser parameters and optics can be utilized to cut different materials by varying depths of various depths. In sapphire, for example, a ternary lens with a focal length of 25 mm can be used with an ultra-fast UV laser to achieve an extended depth of more than 100 microns. In the crucible, a deeper extended depth imaginary (for example, 300 microns) can be achieved with a longer lens and an IR laser with higher power.

如第4A圖至第4C圖所示，亦可選擇或調整一具有像差之聚焦雷射光束216相對於一工件202之一表面204之一焦點偏移量，例如以改變進入工件202內之一延伸DOF 228及/或工件202之表面204上之光束光點大小及能量密度。可將焦點偏移量選擇成例如使進入工件202中之延伸深度虛飾之一深度最佳化並使表面損傷或碎屑最小化。因此可藉由調整焦點偏移量以及其他雷射及光學參數(例如雷射脈波能量)而對延伸深度虛飾進行可調整之深度控制。例如可藉由調整聚焦透鏡224相對於工件202之一位置來調整焦點偏移量。 As shown in FIGS. 4A-4C, a focus offset of the focused laser beam 216 with respect to one surface 204 of a workpiece 202 can also be selected or adjusted, for example, to change into the workpiece 202. A beam spot size and energy density on the surface 204 of the extended DOF 228 and/or workpiece 202. The focus offset can be selected, for example, to optimize depth depth of one of the extended depth imaginary features entering the workpiece 202 and to minimize surface damage or debris. Adjustable depth control of the extended depth imaginary can thus be achieved by adjusting the focus offset and other laser and optical parameters, such as laser pulse energy. The amount of focus shift can be adjusted, for example, by adjusting the position of the focus lens 224 relative to the workpiece 202.

第4A圖顯示具有像差之聚焦雷射光束216以近軸光線聚焦於工件202之一表面204上而未發生焦點偏移，即，近軸焦平面226與表面204實質上重合。圖4B顯示具有像差之聚焦雷射光束216以近軸射線聚焦於工件202之表面204下方且表面204與近軸聚焦表面226之間具有一焦點偏移量δ _f，藉此將有效DOF 228更向工件202中延伸。圖4C顯示具有像差之聚焦雷射光束216以近軸光線聚焦於工件202之表面204下方且表面204與近軸焦平面226之間具有一更大之焦點偏移量δ _f，藉此將有效DOF更進一步向工件202中延伸。 4A shows that the focused laser beam 216 with aberrations is focused on one surface 204 of the workpiece 202 with paraxial rays without a focus shift, i.e., the paraxial focal plane 226 substantially coincides with the surface 204. 4B shows that the focused laser beam 216 with aberrations is focused below the surface 204 of the workpiece 202 with a paraxial ray and has a focus offset δ _f between the surface 204 and the paraxial focusing surface 226, thereby making the effective DOF 228 more Extending into the workpiece 202. 4C shows that the focused laser beam 216 with aberrations is focused below the surface 204 of the workpiece 202 with paraxial rays and a greater focus offset δ _f between the surface 204 and the paraxial focal plane 226, thereby effectively The DOF extends further into the workpiece 202.

最佳焦點偏移量可根據基板材料(例如，切割波長處之折射率)及材料厚度而異，並根據透鏡運作NA及透鏡運作條件下之所得像差係數而異。焦點偏移量亦可端視製程類型(例如，正面型或背面型)而定。對於以10皮秒355奈米雷射在0.16 NA下使用一25毫米三元透鏡切割一90微米至110微米之藍寶石基板之情形，例如對於背面切割而言之最佳焦點偏移量可處於20微米至40微米範圍內。 The optimum focus offset may vary depending on the substrate material (e.g., the refractive index at the dicing wavelength) and the thickness of the material, and may vary depending on the lens operation NA and the resulting aberration coefficient under lens operating conditions. The focus offset can also depend on the type of process (for example, front or back). Cutting a 90- to 110-micron sapphire with a 25 mm ternary lens at 0.16 NA with a 10 picosecond 355 nm laser In the case of a substrate, for example, the optimum focus shift for backside cutting can be in the range of 20 microns to 40 microns.

第5A-5D圖顯示在250微米厚之藍寶石中使用一60毫米焦距之三元透鏡聚焦之一雷射光束之光線幾何分佈，其具有不同球面像差量以及以20微米為增量之不同焦點偏移量。第6A-6D圖顯示在250微米厚之藍寶石中使用一54毫米焦距之二元透鏡聚焦之一雷射光束之光線幾何分佈，其具有不同球面像差量以及以15微米為增量之不同焦點偏移量。第7A-7D圖顯示在120微米厚之藍寶石中使用一25毫米焦距之三元透鏡聚焦之一雷射光束之光線幾何分佈，其具有不同球面像差量以及以10微米為增量之不同焦點偏移量。 Figures 5A-5D show the ray geometry of a laser beam focused on a 250 micron thick sapphire using a 60 mm focal length ternary lens with different spherical aberrations and different focal points in increments of 20 microns. Offset. Figures 6A-6D show the ray geometry of a laser beam focused on a 250 micron thick sapphire using a 54 mm focal length binocular lens with different spherical aberrations and different focal points in increments of 15 microns. Offset. Figures 7A-7D show the ray geometry of a laser beam focused on a 120 micron thick sapphire using a 25 mm focal length ternary lens with different spherical aberrations and different focal points in increments of 10 microns. Offset.

一理想透鏡將提供第5A圖、第6A圖、及第7A圖所示之近軸光線幾何分佈。根據本文所述各實施例，具有一衍射受限區域之一實際透鏡會引入如第5B-5D圖、第6B-6D圖、及第7B-7D圖所示之球面像差。第5B圖、第6B圖、及第7B圖例示由一均勻雷射光束在整個孔徑處照射一實際透鏡而提供之具有像差之光線之光線幾何分佈。第5C圖、第6C圖、及第7C圖例示由一高斯(Gaussian)雷射光束在整個孔徑處照射一實際透鏡而提供之具有像差之光線之光線幾何分佈。第5D圖、第6D圖、及第7C圖例示由一高斯雷射光束在部分孔徑處照射一實際透鏡而提供之具有像差之光線之光線幾何分佈。 An ideal lens will provide the paraxial ray geometry as shown in Figures 5A, 6A, and 7A. According to various embodiments described herein, an actual lens having one of the diffraction limited regions introduces spherical aberration as shown in Figures 5B-5D, 6B-6D, and 7B-7D. Figures 5B, 6B, and 7B illustrate the ray geometry of the rays with aberrations provided by a uniform laser beam illuminating an actual lens across the aperture. Figures 5C, 6C, and 7C illustrate the ray geometry of the rays with aberrations provided by a Gaussian laser beam that illuminates an actual lens across the aperture. 5D, 6D, and 7C illustrate the ray geometry of the rays with aberrations provided by a Gaussian laser beam illuminating an actual lens at a portion of the aperture.

在所示實例中，當孔徑過大(第5B圖、第5C圖、第6B圖、第6C圖、第7B圖、及第7C圖)時，橫向球面像差範圍過大，且具有像差之聚焦光束會被放大。在部分孔徑(第5D圖、第6D圖、及第7D圖)下，具有像差之聚焦光束與近軸或理想透鏡(第5A圖、第6A圖、及第7A圖)相比具有一相對緊湊之焦點且具有一延伸之有效DOF。因此，根據一個實例，對於特定基板材料及厚度而言，所期望之透鏡與NA組合會產生幾乎衍射受限之橫向光點大小，但同時產生足以延伸有效DOF以與材料厚度相匹配之一縱向球面像差範圍。 In the illustrated example, when the aperture is too large (Figs. 5B, 5C, 6B, 6C, 7B, and 7C), the lateral spherical aberration range is too large, and the aberration has the focus. The beam will be amplified. In the partial apertures (5D, 6D, and 7D), the focused beam with aberration has a relative ratio to the paraxial or ideal lens (Fig. 5A, Fig. 6A, and Fig. 7A). Compact focus and an extended effective DOF. Thus, according to one example, for a particular substrate material and thickness, the desired combination of lens and NA produces a nearly diffraction-limited lateral spot size, but at the same time produces a longitudinal direction sufficient to extend the effective DOF to match the thickness of the material. Spherical aberration range.

儘管藉由具有25毫米、54毫米、及60毫米之焦距之透鏡來描述特定實例，然而亦可使用具有其他焦距之透鏡來提供所期望之NA及球面像差。舉例而言，焦距可小於25毫米或大於60毫米。 Although specific examples are described by lenses having focal lengths of 25 mm, 54 mm, and 60 mm, lenses having other focal lengths can also be used to provide the desired NA and spherical aberration. For example, the focal length can be less than 25 mm or greater than 60 mm.

第8圖及第9圖顯示藉由一系列雷射脈波切割一藍寶石基板802且使藍寶石基板802中具有延伸深度虛飾之照片。每一雷射脈波形成一供雷射進入藍寶石基板802之燒蝕區或孔806，其中燒蝕孔806周圍環繞有一雷射區805，且一延伸深度虛飾通道808自燒蝕孔806延伸至基板802之材料中。因此，基板802可沿由該一系列燒蝕孔806及延伸深度虛飾通道808形成之切割線而被分開。 Figures 8 and 9 show a photograph of a sapphire substrate 802 cut by a series of laser pulses and having an extended depth smear in the sapphire substrate 802. Each of the laser pulses forms a laser into the ablation region or aperture 806 of the sapphire substrate 802, wherein the ablation aperture 806 is surrounded by a laser region 805, and an extended depth imaginary channel 808 extends from the ablation aperture 806. Into the material of the substrate 802. Thus, the substrate 802 can be separated along a cutting line formed by the series of ablation holes 806 and the extended depth embossed channels 808.

在所示實施例中，燒蝕孔806約為5微米寬並具有一20微米之雷射區805且間距為約15微米，且延伸深度虛飾通道808延伸至150微米厚之藍寶石基板802中約100微米。因此，根據本文所述之實施例，藉由延伸深度虛飾進行之切割容許切割部位小於20微米。因此，在切割具有LED之半導體晶圓時，切割部位越小(例如與隱形切割相比)，則所容許之隔道越窄(例如，小於25微米)且晶粒間距越小，而不會造成顯著損壞及碎屑。即使當切割部位間之間距較大時，延伸深度虛飾通道808之深度亦能夠改良沿切割線之斷開。延伸深度虛飾通道808之深度亦使得能夠切割較厚之基板而無需例如如隱形切割所需般使雷射在基板內不同焦點處進行多遍掃描。例如，與使用交疊脈波相比，切割部位之間距容許藉由對每一切割部位使用單個脈波而更快地切割。 In the illustrated embodiment, the ablation via 806 is about 5 microns wide and has a 20 micron laser region 805 and a pitch of about 15 microns, and the extended depth imaginary channel 808 extends into the 150 micron thick sapphire substrate 802. About 100 microns. Thus, according to embodiments described herein, the cutting by extended depth imaginary allows the cutting site to be less than 20 microns. Therefore, when cutting a semiconductor wafer with LEDs, the smaller the cut portion (for example, compared to stealth dicing), the narrower the allowable channel (for example, less than 25 microns) and the smaller the grain pitch, without Causes significant damage and debris. Even when the distance between the cutting portions is large, the depth of the extended depth embossed channel 808 can improve the break along the cutting line. Extending the depth of the imaginary channel 808 also enables the cutting of thicker substrates without the need to perform multiple passes of the laser at different focal points within the substrate, as required, for example, for invisible dicing. For example, the distance between the cutting sites allows for faster cutting by using a single pulse for each cutting site as compared to using overlapping pulse waves.

可藉由不同之雷射參數(例如，藉由控制脈波間距及深度)來達成其他切割部位尺寸、深度、及間距。儘管可對每一部位使用單個脈波，然而亦可例如藉由多遍地掃描雷射來對每一切割部位使用多個脈波以控制深度。儘管所示實施例顯示約15微米之一間距及約100微米之一深度，然而可將間距控制成自相互交疊至20微米或以上，並可將深度控制成小於100微米至大於 200微米。 Other cutting site sizes, depths, and spacings can be achieved by varying laser parameters (eg, by controlling pulse spacing and depth). Although a single pulse wave can be used for each portion, it is also possible to use a plurality of pulse waves for each cutting portion to control the depth, for example, by scanning the laser multiple times. Although the illustrated embodiment exhibits a pitch of about 15 microns and a depth of about 100 microns, the pitch can be controlled to overlap from each other to 20 microns or more, and the depth can be controlled to be less than 100 microns to greater than 200 microns.

在其他變型中，可針對一脈波序列中之不同脈波使用不同深度。一脈波序列例如可包含一系列頻率較高之較淺脈波(例如，由5微米至10微米間隔開之10微米至20微米深度)以及一間隔頻率較低(例如，每15微米至50微米)之較深脈波(例如，50微米至100微米)。換言之，一系列較深脈波可以較長距離間隔開，並使較淺脈波位於較深脈波之間以增強斷開特性。因此，藉由改良斷開特性及斷開良率，產生延伸深度虛飾及可控深度及間距之切割在生產LED時可尤其有利，乃因來自LED之光傳播效應更能夠到達藍寶石側壁之底部或中間。於其中較少關注光損失之情形中(例如在矽晶圓中)可使用更緊密且更深之間距。 In other variations, different depths may be used for different pulse waves in a pulse train sequence. A pulse sequence may, for example, comprise a series of shallower pulses of higher frequency (eg, 10 micrometers to 20 micrometers spaced apart from 5 micrometers to 10 micrometers) and a lower spacing frequency (eg, every 15 micrometers to 50 micrometers) Deeper pulse waves (eg, 50 microns to 100 microns). In other words, a series of deeper pulse waves can be spaced apart over longer distances and the shallower pulse waves are located between the deeper pulse waves to enhance the break characteristics. Therefore, by improving the breaking characteristics and breaking the yield, the cutting of the extended depth imaginary and the controllable depth and spacing can be particularly advantageous when producing the LED, because the light propagation effect from the LED can reach the bottom of the sapphire sidewall. Or in the middle. In situations where less attention is paid to light loss (eg, in germanium wafers), tighter and deeper spacing can be used.

參照第10A圖及第10B圖，根據另一實施例，一雷射加工系統1000包含一氣浮(air bearing)X-Y定位台1030，以用於支撐及定位一工件1002，進而藉由延伸深度虛飾進行切割。雷射加工系統1000包括安裝於一側(例如，頂側或前側)上之一雷射光束遞送系統1020以及安裝於一相對側(例如，底側或後側)上之一相對側照相機1040。定位台1030之至少一工件支撐部1034被配置成在使相對側照相機1040面向工件1002之一對齊位置(第10A圖)與使雷射光束遞送系統1020面向工件1002之一加工位置(第10B圖)之間滑動。雷射光束遞送系統1020高於支撐部1034上之一工件支撐表面之一平面1001，且相對側照相機1040低於支撐部1034上之工件支撐表面之平面1001。美國專利申請第12/962,050號中更詳細地描述了氣浮X-Y定位台之一實例，該美國專利申請以引用方式全文併入本文中。 Referring to FIGS. 10A and 10B, according to another embodiment, a laser processing system 1000 includes an air bearing XY positioning table 1030 for supporting and positioning a workpiece 1002, thereby extending the depth of the workpiece. Cut. Laser processing system 1000 includes a laser beam delivery system 1020 mounted on one side (eg, a top side or a front side) and an opposite side camera 1040 mounted on an opposite side (eg, a bottom side or a back side). At least one workpiece support portion 1034 of the positioning table 1030 is configured to position the opposite side camera 1040 toward one of the workpieces 1002 (Fig. 10A) and the laser beam delivery system 1020 to one of the workpieces 1002 (Fig. 10B) Between the slides. The laser beam delivery system 1020 is higher than one of the planes 1001 of one of the workpiece support surfaces on the support portion 1034, and the opposite side camera 1040 is lower than the plane 1001 of the workpiece support surface on the support portion 1034. An example of an airfloating X-Y locating station is described in more detail in U.S. Patent Application Serial No. 12/962,050, the disclosure of which is incorporated herein in its entirety.

在對齊位置上，相對側照相機1040對工件1002之面向照相機1040之一側1005上的一特徵進行成像並產生代表該特徵之影像資料。由相對側照相機1040所產生之影像資料可用於定位工件1002，俾使例如使用熟習此項技術者所習知之機器視覺系統及對齊技術而使雷射光束遞送系統1020相對於在工件1002之相對側1005上所成像之特徵對齊。在加工位置上，雷射光束遞送系統1020朝工件1002之面向光束遞送系統1020之一側1003引導一聚焦雷射光束1016(例如，具有一延伸DOF且具有像差之聚焦雷射光束)並使用如上所述藉由延伸深度虛飾進行之切割來加工工件1002。 In the aligned position, the opposite side camera 1040 images a feature on the side 1005 of the workpiece 1002 that faces the camera 1040 and produces image material representative of the feature. The image data produced by the opposite side camera 1040 can be used to position the workpiece 1002 such that the laser beam delivery system 1020 is opposite the opposite side of the workpiece 1002, for example, using machine vision systems and alignment techniques known to those skilled in the art. The features imaged on the 1005 are aligned. In the processing position, the laser beam is delivered The delivery system 1020 directs a focused laser beam 1016 (e.g., a focused laser beam having an extended DOF with aberrations) toward one side 1003 of the workpiece 1002 facing the beam delivery system 1020 and using the extended depth virtual as described above The cut is performed to machine the workpiece 1002.

雷射加工系統1000亦包含一運動控制系統1050，以用於在工件1002之對齊及/或加工期間控制定位台1030之運動。運動控制系統1050可根據由相對側照相機1040所產生之影像資料而產生對齊資料，並因應該對齊資料而控制定位台1030之運動。 The laser processing system 1000 also includes a motion control system 1050 for controlling the motion of the positioning stage 1030 during alignment and/or processing of the workpiece 1002. Motion control system 1050 can generate alignment data based on image data generated by opposite side camera 1040 and control the motion of positioning stage 1030 as appropriate.

雷射光束遞送系統1020可包含透鏡及其他光學元件，以用於例如如上所述修改並聚焦由一雷射所產生之一原始雷射光束。雷射(圖未示出)例如可被定位於雷射加工系統1000之一平台上，且由雷射所產生之原始雷射光束可被引導至雷射光束遞送系統1020中。 The laser beam delivery system 1020 can include lenses and other optical components for modifying and focusing, for example, one of the original laser beams produced by a laser as described above. A laser (not shown) may be positioned, for example, on one of the laser processing systems 1000, and the original laser beam produced by the laser may be directed into the laser beam delivery system 1020.

雷射加工系統1000亦可包含一正面照相機1044，以用於在正面上對工件1002進行成像。正面照相機1044可被安裝至光束遞送系統1020或其他適宜位置。正面照相機1044可類似地耦合至運動控制系統1050，俾使運動控制系統1050可使用自正面照相機1044產生之影像資料來提供對齊。因此，雷射加工系統1000可容許自與雷射光束相對之背面或自正面或與雷射光束相同之側對齊。相對側照相機1040及正面照相機1044可為熟習此項技術者習知的用於在雷射加工應用中對齊半導體晶圓之高解析度照相機。 The laser processing system 1000 can also include a front camera 1044 for imaging the workpiece 1002 on the front side. Front camera 1044 can be mounted to beam delivery system 1020 or other suitable location. The front camera 1044 can be similarly coupled to the motion control system 1050 such that the motion control system 1050 can use the image data generated from the front camera 1044 to provide alignment. Thus, the laser processing system 1000 can be allowed to align with the back side opposite the laser beam or from the front side or the same side as the laser beam. The opposite side camera 1040 and front side camera 1044 can be high resolution cameras well known to those skilled in the art for aligning semiconductor wafers in laser processing applications.

因此，雷射加工系統1000可用於將光束遞送系統1020及聚焦雷射光束1016與一半導體晶圓上各晶粒間之隔道對齊。當適當對齊時，X-Y定位台1030可移動工件1002以在工件1002上掃描雷射光束，俾使一系列脈波例如沿一晶圓上各晶粒間之一隔道或沿晶圓之與隔道相對之一側切割工件1002。X-Y定位台1030可隨後移動工件以轉位至另一隔道進行切割。可視需要重複對齊過程，以在其他隔道內或沿其他隔道進行切割。 Thus, the laser processing system 1000 can be used to align the beam delivery system 1020 and the focused laser beam 1016 with the channels between the various dies on a semiconductor wafer. When properly aligned, the XY positioning stage 1030 can move the workpiece 1002 to scan the laser beam on the workpiece 1002, such that a series of pulse waves, for example, along one of the wafers on a wafer or along the wafer The track cuts the workpiece 1002 on one side. The X-Y positioning stage 1030 can then move the workpiece to index to another lane for cutting. The alignment process can be repeated as needed to cut in other channels or along other channels.

參照第11圖，可使用相對側對齊來利於一半導體晶圓1101之背面切割，進而分開複數個半導體晶粒(例如，LED)。半導體晶圓1101可包含一基板1102(例如，藍寶石)及形成於由隔道1107所隔開之區段1109中之一或多層半導體材料(例如，GaN)。半導體晶圓1101的具有區段1109之側被稱為正面1103，且相對側被稱為背面1105。基板1102亦可在與區段1109相對之背面1105上具有一或多個層1104(例如，金屬)。 Referring to Figure 11, the relative side alignment can be used to facilitate a semiconductor crystal. The back side of the circle 1101 is diced, thereby separating a plurality of semiconductor dies (eg, LEDs). The semiconductor wafer 1101 can include a substrate 1102 (eg, sapphire) and one or more layers of semiconductor material (eg, GaN) formed in the segment 1109 separated by the via 1107. The side of the semiconductor wafer 1101 having the section 1109 is referred to as the front side 1103, and the opposite side is referred to as the back side 1105. Substrate 1102 can also have one or more layers 1104 (eg, metal) on back side 1105 opposite section 1109.

一雷射加工系統(例如，上述雷射加工系統)可用於沿晶粒區段1109間之隔道1107切割半導體晶圓1101，以將半導體晶圓1101分成各個晶粒。因此，半導體晶圓1101被對齊成使一雷射光束1116在半導體晶圓1101上射於隔道1107之間，進而對準晶粒區段1109與雷射光束1116。如上所述，可藉由形成具有延伸深度虛飾1108之一系列燒蝕區1106來切割半導體晶圓1101。形成延伸深度虛飾及燒蝕之切割在層1104為不透明時尤其有利，乃因燒蝕能夠移除層1104並使雷射光束1116能夠進入基板1102。在另一變型中，可使用一雷射之一第一遍掃描來燒蝕及移除層1104，且一雷射之一第二遍掃描會提供延伸深度虛飾。 A laser processing system (e.g., the laser processing system described above) can be used to diced the semiconductor wafer 1101 along the via 1107 between the die segments 1109 to divide the semiconductor wafer 1101 into individual dies. Thus, the semiconductor wafer 1101 is aligned such that a laser beam 1116 is incident on the semiconductor wafer 1101 between the vias 1107, thereby aligning the die segments 1109 with the laser beam 1116. As described above, the semiconductor wafer 1101 can be diced by forming a series of ablated regions 1106 having an extended depth imaginary 1108. The formation of the extended depth smear and ablation cut is particularly advantageous when the layer 1104 is opaque because the ablation can remove the layer 1104 and enable the laser beam 1116 to enter the substrate 1102. In another variation, one of the first passes of a laser can be used to ablate and remove layer 1104, and a second pass of one of the lasers provides an extended depth illusion.

當對半導體晶圓1101之背面1105進行雷射加工時，半導體晶圓1101可被定位成使晶圓1101之正面1103上之晶粒區段1109面向相對側照相機1140。因此，相對側照相機1140可用於觀察各區段1109間之隔道1107，並使隔道1107相對於雷射光束1116之一位置對齊。利用相對側照相機1140之對齊在背面層1104為不透明(例如，金屬)且妨礙自加工側進行對齊時尤其有利。為提供此種對齊，晶圓1101沿Y軸相對於雷射光束遞送系統(圖未示出)被定位成使由雷射光束1116在晶圓1101之背面1105上形成之切割線位於正面1103之隔道1107之寬度內。 When laser processing the back side 1105 of the semiconductor wafer 1101, the semiconductor wafer 1101 can be positioned such that the die segments 1109 on the front side 1103 of the wafer 1101 face the opposite side camera 1140. Thus, the opposite side camera 1140 can be used to view the channel 1107 between the segments 1109 and align the channel 1107 with respect to one of the laser beams 1116. It is especially advantageous when the alignment of the opposite side camera 1140 is opaque (e.g., metal) on the backside layer 1104 and interferes with alignment from the machine side. To provide such alignment, the wafer 1101 is positioned along the Y-axis relative to the laser beam delivery system (not shown) such that the cutting line formed by the laser beam 1116 on the back side 1105 of the wafer 1101 is located on the front side 1103. Within the width of the corridor 1107.

參見第12A圖及第12B圖，可使用相對側對齊來利於雙面切割。一般而言，雙面切割涉及在一工件之兩個面上形成相對淺之切割線，且其中一條切割線相對於其中另一條切割線實質上對齊。形成淺的切割線能夠最小化或避免由較深之切割線可能造成之損傷，同時在兩個面上具有切割線可提高斷開良率，乃因裂紋更可能在切割線之間傳播。 Referring to Figures 12A and 12B, relative side alignment can be used to facilitate double-sided cutting. In general, double-sided cutting involves forming relatively shallow cutting lines on both sides of a workpiece, and one of the cutting lines is substantially aligned with respect to the other of the cutting lines. Forming shallow cutting lines minimizes or avoids damage that can be caused by deeper cutting lines, while having cut lines on both sides improves the break yield. Cracks are more likely to propagate between the cutting lines.

根據一種實例性方法，一半導體晶圓1201可首先被定位成(例如，定位於工件支撐件上)使一背面1205面向一雷射光束遞送系統(圖未示出)且一正面1203面向一相對側照相機1240(第4A圖)。當晶圓1201位於此位置時，可使用相對側照相機1240對各區段1209間之隔道1207其中之一進行成像，俾使晶圓1201可被定位成使背面1205上之雷射光束1216與正面1203上之隔道1207對齊。當半導體晶圓1201已對齊時，可使用雷射光束1216切割背面1205，進而形成一相對淺之背面切割線1206a(例如，為20微米或以下)。 In accordance with an exemplary method, a semiconductor wafer 1201 can be first positioned (e.g., positioned on a workpiece support) such that a back surface 1205 faces a laser beam delivery system (not shown) and a front surface 1203 faces a relative Side camera 1240 (Fig. 4A). When the wafer 1201 is in this position, one of the channels 1207 between the segments 1209 can be imaged using the opposite side camera 1240 such that the wafer 1201 can be positioned such that the laser beam 1216 on the back surface 1205 is The channels 1207 on the front side 1203 are aligned. When the semiconductor wafer 1201 has been aligned, the back side 1205 can be cut using the laser beam 1216 to form a relatively shallow back cut line 1206a (eg, 20 microns or less).

隨後可將半導體晶圓1201翻轉，俾使正面1203面向雷射光束遞送系統且背面1205面向相對側照相機1240(第4B圖)。當晶圓1201處於此位置時，可使用相對側照相機1240對背面切割線1206a進行成像，俾使晶圓1201可被定位成使雷射光束1216與背面切割線1206a對齊。當半導體晶圓1201已對齊時，可使用雷射光束1216在各區段1209間之隔道1207中切割正面1203，以形成與背面切割線1206a實質上對齊之一正面切割線1206b。例如，如上所述，正面切割線1206b可包含具有延伸深度虛飾1208之一系列燒蝕區。作為由相對側照相機1240提供對齊之附加或替代，一加工側照相機1244可對隔道1207進行成像以使雷射光束1216與隔道1207對齊。 The semiconductor wafer 1201 can then be flipped such that the front side 1203 faces the laser beam delivery system and the back side 1205 faces the opposite side camera 1240 (Fig. 4B). When the wafer 1201 is in this position, the backside cut line 1206a can be imaged using the opposite side camera 1240 such that the wafer 1201 can be positioned to align the laser beam 1216 with the back cut line 1206a. When the semiconductor wafer 1201 has been aligned, the laser beam 1216 can be used to cut the front side 1203 in the channel 1207 between the segments 1209 to form a front cut line 1206b that is substantially aligned with the back cut line 1206a. For example, as described above, the front cut line 1206b can comprise a series of ablated regions having an extended depth imaginary 1208. Additionally or alternatively to providing alignment by the opposite side camera 1240, a processing side camera 1244 can image the channel 1207 to align the laser beam 1216 with the channel 1207.

隨後，晶圓1201可藉由以下方式而被分成各個晶粒：沿切割線1206a、1206b之位置斷開，俾使裂紋在延伸深度虛飾1208之促進下在切割線1206a與1206b之間傳播。當各區段1209對應於各LED時，例如，正面切割線1206b會更佳地界定LED之邊緣，俾使LED更均勻並提高斷開良率(例如，相較於僅在一側上具有淺切割線之情形)。此外，對LED光及電性特性造成不利影響之可能性更小，乃因切割線1206a、1206b之深度不足以造成顯著之熱損傷。 Subsequently, the wafer 1201 can be divided into individual dies by breaking along the locations of the dicing lines 1206a, 1206b such that the crack propagates between the dicing lines 1206a and 1206b with the aid of the extended depth imaginary 1208. When each segment 1209 corresponds to each LED, for example, the front cut line 1206b will more preferably define the edge of the LED, making the LED more uniform and increasing the break yield (eg, shallower than on only one side) The case of the cutting line). In addition, the possibility of adversely affecting the LED light and electrical characteristics is less likely because the depth of the cut lines 1206a, 1206b is insufficient to cause significant thermal damage.

根據另一替代方法，具有延伸深度虛飾1208之正面切割線1206b可首先形成於正面1203上(例如，使用加工側照相機1244提供相對於隔道1207之對齊)。隨後可將晶圓1201翻轉並可在背面1205上形成背面切割線1206a(例如，使用相對側照相機1240提供相對於正面切割線1206b及/或隔道1207之對齊)。其中一條切割線可淺於另一條切割線。舉例而言，可首先形成較淺之切割線(例如，為20微米或以下)，並使第二條較深切割線與該較淺切割線對齊。根據一雙面切割方法之另一變型，背面切割線1206a可形成有延伸深度虛飾1208。 According to another alternative, the front side of the extended depth imaginary 1208 The cutting line 1206b can be formed first on the front side 1203 (eg, using the machine side camera 1244 to provide alignment relative to the shroud 1207). The wafer 1201 can then be flipped over and a back cut line 1206a can be formed on the back side 1205 (eg, using the opposing side camera 1240 to provide alignment with respect to the front cut line 1206b and/or the channel 1207). One of the cutting lines can be shallower than the other. For example, a shallower cut line (eg, 20 microns or less) may be formed first, and a second deeper cut line may be aligned with the shallower cut line. According to another variation of a double-sided cutting method, the back cut line 1206a can be formed with an extended depth imaginary 1208.

參照第13圖，以下將更詳細地描述用於藉由延伸深度虛飾來切割一工件1302(例如，一半導體晶圓之一藍寶石基板)之一雷射加工系統1300之另一實施例。雷射加工系統1300可包含一超快雷射1310及一光束遞送系統1320，超快雷射1310能夠以一能夠至少部分穿透材料之波長射出超短脈波(例如，小於1奈秒)，光束遞送系統1320能夠提供良好聚焦之直線光束1316。光束遞送系統1320之一個實施例包含：一擴束器1322，用於擴張來自超快雷射1310之原始雷射光束1321，以形成一擴張光束1323；一光束成形器1326，用於使擴張光束1323成形，以形成一橢圓形光束1325；以及一聚焦透鏡1324，用於聚焦橢圓形光束1325，以提供良好聚焦之直線光束1316，直線光束1316在工件1302上形成一直線光束光點且在工件1302中具有一延伸DOF。光束遞送系統1320亦可包含一或多個反射器1328，以視需要反射及重定向雷射光束。 Referring to Figure 13, another embodiment of a laser processing system 1300 for cutting a workpiece 1302 (e.g., one of the sapphire substrates of a semiconductor wafer) by extending the depth imaginary will be described in greater detail below. The laser processing system 1300 can include an ultrafast laser 1310 and a beam delivery system 1320 that can emit ultrashort pulses (eg, less than one nanosecond) at a wavelength that is at least partially penetrating the material. Beam delivery system 1320 is capable of providing a well focused linear beam 1316. One embodiment of beam delivery system 1320 includes a beam expander 1322 for expanding the original laser beam 1321 from ultrafast laser 1310 to form an expanded beam 1323; a beam shaper 1326 for dilating the beam 1323 is shaped to form an elliptical beam 1325; and a focusing lens 1324 is used to focus the elliptical beam 1325 to provide a well-focused linear beam 1316 that forms a linear beam spot on the workpiece 1302 and at the workpiece 1302 There is an extended DOF in it. Beam delivery system 1320 can also include one or more reflectors 1328 to reflect and redirect the laser beam as desired.

如先前所述，延伸深度虛飾切割涉及在工件1302之表面1304上在燒蝕區1306中燒蝕材料以及使用一波導自聚焦效應將雷射光束1316自燒蝕區1306射至在工件1302內延伸之一內部位置1308，在內部位置1308處由於震動、電場、及/或壓力而造成晶體損傷。聚焦透鏡1324可如上所述引入球面像差，其中一縱向球面像差範圍足以將有效DOF延伸至工件1302中。 As previously described, the extended depth imaginary cut involves ablating the material in the ablated region 1306 on the surface 1304 of the workpiece 1302 and directing the laser beam 1316 from the ablated region 1306 into the workpiece 1302 using a waveguide self-focusing effect. One of the internal positions 1308 is extended, causing crystal damage at internal position 1308 due to vibration, electric field, and/or pressure. Focusing lens 1324 can introduce spherical aberration as described above, with a range of longitudinal spherical aberrations sufficient to extend the effective DOF into workpiece 1302.

光束遞送系統1320例如可包含能夠形成一可變細長散光聚焦光束光點(variable elongated astigmatic focal beam spot) 之光束成形光學器件，如美國專利第7,388,172號中所更詳細描述，該美國專利以引用方式全文併入本文中。該細長散光聚焦光束光點沿散光軸之一長度大於沿聚焦軸之一寬度。此種光束遞送系統能夠隨光點長度之改變而控制可變散光聚焦光束光點之能量密度。光束成形器1326例如可包含一變形透鏡(anamorphic lens)系統，該變形透鏡系統包含一圓柱形平凹透鏡(plano-concave lens)1326a及一圓柱形平凸透鏡(plano-convex lens)1326b，俾改變該等透鏡間之一距離便能夠改變工件上之光束光點長度及能量密度。 Beam delivery system 1320, for example, can include a variable elongated astigmatic focal beam spot capable of forming a variable elongated astigmatic focal beam spot The beam shaping optics are described in more detail in U.S. Patent No. 7,388,172, the disclosure of which is incorporated herein in its entirety by reference. The length of the elongated astigmatic focused beam spot along one of the astigmatism axes is greater than the width along one of the focus axes. Such a beam delivery system is capable of controlling the energy density of the variable astigmatic focused beam spot as the length of the spot changes. The beam shaper 1326 can, for example, comprise an anamorphic lens system comprising a cylindrical plano-concave lens 1326a and a cylindrical plano-convex lens 1326b. A distance between the lenses can change the beam spot length and energy density on the workpiece.

雷射加工系統1300可根據具體應用而進一步修改光束，以改良切割線之品質。為在某些應用(例如，背面切割)中避免外延層層離(delamination)問題，例如，雷射加工系統1300可在光束之邊緣處提供空間濾波，以清理(clean up)光束之窄方向上之點分佈函數(point spread function)。 The laser processing system 1300 can further modify the beam depending on the particular application to improve the quality of the cutting line. To avoid epitaxial delamination problems in certain applications (eg, backside dicing), for example, laser processing system 1300 can provide spatial filtering at the edges of the beam to clean up the beam in a narrow direction. Point spread function.

因此，光束成形器1326可用於改變工件1302上之光束光點之能量密度，以最佳化對於特定材料或切割操作之積分通量(fluence)及耦合效率。當對一經GaN塗覆之藍寶石基板執行雙面切割時，例如，可將光束光點之能量密度調整得較高以最佳化對裸藍寶石之切割(即，背面切割)，並可將光束光點之能量密度調整得較低以最佳化對經GaN塗覆之藍寶石之切割(即，正面切割)。換言之，可使用針對工件之一側最佳化之雷射光束光點切割該側，可將工件翻轉，並可使用針對另一側最佳化之雷射光束光點切割該另一側。因此，光束成形器1326無需調整雷射功率來改變能量密度並最佳化積分通量。 Thus, beam shaper 1326 can be used to vary the energy density of the beam spot on workpiece 1302 to optimize the fluence and coupling efficiency for a particular material or cutting operation. When performing double-sided cutting on a GaN-coated sapphire substrate, for example, the energy density of the beam spot can be adjusted to be higher to optimize the cutting of the bare sapphire (ie, the back side cutting), and the beam light can be The energy density of the dots is adjusted lower to optimize the cutting of the GaN-coated sapphire (ie, front cut). In other words, the side can be cut using a laser beam spot optimized for one side of the workpiece, the workpiece can be flipped, and the other side can be cut using a laser beam spot optimized for the other side. Thus, beam shaper 1326 does not need to adjust the laser power to change the energy density and optimize the fluence.

在其他實施例中，可使用一非線性光學晶體(例如BBO晶體或β-BaB₂O₄)作為一光束成形器。BBO晶體已知與一雷射一起用作一倍頻晶體(frequency-doubling crystal)。因BBO晶體相較於其他晶體(例如CLBO)提供更大之走離(walk-off)效應，故進入晶體之實質圓形光束可在離開晶體時變成一橢圓形光束。儘管可能在許多應用中不期望產生走離效應，然而BBO晶體之此種特性在其中期望具有一橢圓形光束之應用中提供獨特之優點。 In other embodiments, a nonlinear optical crystal (e.g., BBO crystal or β-BaB ₂ O ₄ ) can be used as a beam shaper. BBO crystals are known to be used together with a laser as a frequency-doubling crystal. Since the BBO crystal provides a greater walk-off effect than other crystals (e.g., CLBO), the substantially circular beam entering the crystal can become an elliptical beam as it leaves the crystal. While it may not be desirable to have a walk-off effect in many applications, such characteristics of BBO crystals offer unique advantages in applications where it is desirable to have an elliptical beam.

因此，用於藉由延伸深度虛飾而進行切割之雷射加工系統及方法提供優於習知燒蝕切割及隱形切割技術之若干優點。具體而言，藉由延伸深度虛飾進行之切割能夠以最小或顯著減少之熱及碎屑切割一工件(例如，一半導體晶圓之一藍寶石基板)。藉由減少或最小化所產生之熱及碎屑，可以低電性損傷及光損失來製造LED且無需額外之塗覆及清潔製程。藉由延伸深度虛飾進行之切割亦有利於切割較厚工件及具有不透明塗層或膜之工件。藉由延伸深度虛飾進行之切割亦無需使用習知隱形切割系統中之複雜且昂貴之高NA透鏡及聚焦系統。如本文所述，藉由延伸深度虛飾進行之切割可藉由調整處理參數(例如，波長、脈波持續時間、脈波能量)及光學器件而在各種類型之材料中達成。 Thus, laser processing systems and methods for cutting by extending depth smudges provide several advantages over conventional ablation cutting and stealth cutting techniques. In particular, cutting by extended depth imaginary can cut a workpiece (eg, one sapphire substrate of a semiconductor wafer) with minimal or significantly reduced heat and debris. By reducing or minimizing the heat and debris generated, LEDs can be fabricated with low electrical damage and light loss without the need for additional coating and cleaning processes. Cutting by extending the depth imaginary also facilitates the cutting of thicker workpieces and workpieces having opaque coatings or films. The cutting by extending the depth illusion also eliminates the need for complex and expensive high NA lenses and focusing systems in conventional stealth cutting systems. As described herein, dicing by extending depth imaginary can be achieved in various types of materials by adjusting processing parameters (eg, wavelength, pulse duration, pulse energy) and optics.

根據一個實施例，一種用於雷射切割一工件之方法包含：產生具有複數個超短脈波之一雷射光束，該等超短脈波具有小於1奈秒之一脈波持續時間；以及聚焦該雷射光束，俾使一能量密度足以於一燒蝕區處燒蝕該基板之一表面且足以改變該工件中之一折射率，其中該光束利用一波導自聚焦效應穿透該燒蝕區而到達該工件內之一內部位置，以於該內部位置處對該工件之材料造成晶體損傷。 According to one embodiment, a method for laser cutting a workpiece includes: generating a laser beam having a plurality of ultrashort pulse waves having a pulse duration of less than 1 nanosecond; Focusing the laser beam such that an energy density is sufficient to ablate one surface of the substrate at an ablation region and is sufficient to change a refractive index of the workpiece, wherein the beam penetrates the ablation using a waveguide self-focusing effect The zone reaches an internal location within the workpiece such that the interior location causes crystal damage to the material of the workpiece.

根據另一實施例，一種用於雷射切割一工件之方法包含：產生一雷射光束，該雷射光束具有足以於該工件之材料內提供非線性多光子吸收之一波長、一脈波持續時間、及一脈波能量；使用一透鏡聚焦該雷射光束，該透鏡引入具有一縱向球面像差範圍之球面像差，該縱向球面像差範圍足以於該工件內提供一延伸景深(DOF)，俾使該雷射光束之單個脈波於該工件內產生一延伸深度虛飾；以及藉由該雷射光束掃描該工件，俾使一系列脈波沿該工件於一系列位置處產生一系列延伸深度虛飾。 In accordance with another embodiment, a method for laser cutting a workpiece includes: generating a laser beam having a wavelength sufficient to provide nonlinear multiphoton absorption within the material of the workpiece, a pulse lasting Time, and a pulse energy; focusing the laser beam with a lens that introduces a spherical aberration having a range of longitudinal spherical aberrations sufficient to provide an extended depth of field (DOF) within the workpiece Causing a single pulse of the laser beam to create an extended depth imaginary within the workpiece; and scanning the workpiece by the laser beam to cause a series of pulses to produce a series of positions along the workpiece at a series of locations Extend the depth of the illusion.

根據再一實施例，一種雷射加工系統包含：一雷射，用於產生一雷射光束，該雷射光束具有足以於該工件之材料內提供非線性多光子吸收之一波長、一脈波持續時間、及一脈波能量；以及一光束遞送系統，用於聚焦該雷射光束並朝一工件引導該雷射光束。該光束遞送系統包含一擴束器及一透鏡，該擴束器用於擴張該雷射光束，該透鏡用於引入具有一縱向球面像差範圍之球面像差，該縱向球面像差範圍足以於該工件內提供一延伸景深(DOF)，俾使該雷射光束之單個脈波於該工件內產生一延伸虛飾。該雷射加工系統更包含一工件定位台，以用於移動該工件以於該工件上掃描該雷射光束，俾使一系列脈波於該工件內形成一系列延伸虛飾。 According to still another embodiment, a laser processing system includes: a laser for generating a laser beam having a wavelength sufficient to provide nonlinear multiphoton absorption in a material of the workpiece, a pulse wave Duration, and a pulse energy; And a beam delivery system for focusing the laser beam and directing the laser beam toward a workpiece. The beam delivery system includes a beam expander for expanding the laser beam, and a lens for introducing a spherical aberration having a range of longitudinal spherical aberrations, the longitudinal spherical aberration range being sufficient for the beam An extended depth of field (DOF) is provided within the workpiece such that a single pulse of the laser beam creates an extended embossment within the workpiece. The laser processing system further includes a workpiece positioning stage for moving the workpiece to scan the laser beam on the workpiece to form a series of pulse waves forming a series of extended embossments in the workpiece.

儘管本文已描述了本發明之原理，然而熟習此項技術者應理解，本說明僅以舉例方式給出而非作為對本發明範圍之一限制。除本文所示及所述實例性實施例之外，其他實施例亦涵蓋於本發明範圍內。此項技術中之通常知識者所作之潤飾及替換均被視為屬於本發明之範圍內，本發明之範圍僅受隨附申請專利範圍限制。 Although the principles of the invention have been described herein, it is understood by those skilled in the art that Other embodiments are also encompassed within the scope of the invention in addition to the exemplary embodiments shown and described herein. The refinement and replacement of the present invention by those skilled in the art are considered to be within the scope of the invention, and the scope of the invention is limited only by the scope of the accompanying claims.

100‧‧‧雷射加工系統 100‧‧‧Laser processing system

102‧‧‧工件 102‧‧‧Workpiece

104‧‧‧表面 104‧‧‧ Surface

106‧‧‧燒蝕區 106‧‧‧Ablative area

108‧‧‧內部位置 108‧‧‧Internal position

110‧‧‧雷射 110‧‧‧Laser

112‧‧‧原始雷射光束 112‧‧‧Original laser beam

114‧‧‧擴張光束 114‧‧‧Expanded beam

116‧‧‧聚焦雷射光束 116‧‧‧Focused laser beam

120‧‧‧光束遞送系統 120‧‧‧beam delivery system

122‧‧‧擴束器 122‧‧‧beam expander

124‧‧‧聚焦透鏡 124‧‧‧focus lens

Claims

一種用於雷射切割一工件之方法，該方法包含：產生具有複數個超短脈波之一雷射光束，該等超短脈波具有小於1奈秒(ns)之一脈波持續時間；以及聚焦該雷射光束，俾使一能量密度足以於一燒蝕區處燒蝕該基板之一表面且足以改變該工件中之一折射率，其中該光束利用一波導自聚焦效應(waveguide self-focusing effect)穿透該燒蝕區而到達該工件內之一內部位置，以於該內部位置處對該工件之材料造成晶體損傷(crystal damage)。 A method for laser cutting a workpiece, the method comprising: generating a laser beam having a plurality of ultrashort pulse waves having a pulse duration of less than 1 nanosecond (ns); And focusing the laser beam such that an energy density is sufficient to ablate one surface of the substrate at an ablation region and is sufficient to change a refractive index of the workpiece, wherein the beam utilizes a waveguide self-focusing effect (waveguide self- The focusing effect penetrates the ablation zone to an internal location within the workpiece to cause crystal damage to the material of the workpiece at the interior location.

如請求項1所述之方法，其中聚焦該雷射光束係使用一透鏡執行，該透鏡具有一小於0.8之數值孔徑。 The method of claim 1 wherein focusing the laser beam is performed using a lens having a numerical aperture of less than 0.8.

如請求項2所述之方法，其中該透鏡係為一三元透鏡(lens triplet)。 The method of claim 2, wherein the lens is a lens triplet.

如請求項2所述之方法，其中該透鏡具有一至少25毫米(mm)之焦距。 The method of claim 2, wherein the lens has a focal length of at least 25 millimeters (mm).

如請求項2所述之方法，其中該透鏡以一約400微米(μm)之焦深(focal depth)及一約3微米之切口寬度(kerf width)提供一有效聚焦性能(focusability)。 The method of claim 2, wherein the lens provides an effective focusability with a focal depth of about 400 micrometers (μm) and a kerf width of about 3 micrometers.

如請求項1所述之方法，其中該雷射光束具有一波長，以於該工件之該材料內提供非線性多光子吸收(nonlinear multiphoton absorption)。 The method of claim 1 wherein the laser beam has a wavelength to provide nonlinear multiphoton absorption within the material of the workpiece.

如請求項6所述之方法，其中該材料係為藍寶石，且該波長係處於紫外光(UV)範圍內。 The method of claim 6, wherein the material is sapphire and the wavelength is in the ultraviolet (UV) range.

如請求項7所述之方法，其中產生該雷射光束包含產生至少一個脈波，該至少一個脈波具有一約60微焦耳(μJ)之脈波能量及一小於約10皮秒(ps)之脈波持續時間。 The method of claim 7, wherein generating the laser beam comprises generating at least one pulse wave having a pulse wave energy of about 60 microjoules (μJ) and a less than about 10 picoseconds (ps) The duration of the pulse wave.

如請求項8所述之方法，其中產生該雷射光束包含以一約33.3 千赫(kHz)之重複率產生複數個脈波，且更包含以處於一約70毫米/秒(mm/s)至90毫米/秒範圍之一掃描速度於該工件上掃描該雷射光束。 The method of claim 8 wherein the generating the laser beam comprises an approx. 33.3 The repetition rate of kilohertz (kHz) produces a plurality of pulses, and further includes scanning the laser beam on the workpiece at a scan speed in the range of about 70 mm/sec (mm/s) to 90 mm/sec.

如請求項6所述之方法，其中該波長係處於紅外光(IR)範圍內。 The method of claim 6, wherein the wavelength is in the infrared (IR) range.

如請求項6所述之方法，其中該材料係為藍寶石，該波長係為約355奈米(nm)，且聚焦該雷射光束係使用一25毫米之三元透鏡執行，該25毫米之三元透鏡具有處於一約0.15至0.2範圍之一工作數值孔徑。 The method of claim 6, wherein the material is sapphire, the wavelength is about 355 nanometers (nm), and focusing the laser beam is performed using a 25 mm ternary lens, the 25 mm three The element lens has a working numerical aperture in the range of about 0.15 to 0.2.

如請求項6所述之方法，其中該材料係為藍寶石，該波長係為約355奈米，且聚焦該雷射光束係使用一60毫米之三元透鏡執行，該60毫米之三元透鏡具有處於一約0.05至0.1範圍之一工作數值孔徑。 The method of claim 6, wherein the material is sapphire, the wavelength is about 355 nm, and focusing the laser beam is performed using a 60 mm ternary lens having a 60 mm ternary lens The working numerical aperture is in the range of about 0.05 to 0.1.

如請求項1所述之方法，更包含以一掃描速度於該工件上掃描該雷射光束，俾使該雷射光束之一系列脈波沿一切割線形成一系列燒蝕區及晶體受損內部位置。 The method of claim 1, further comprising scanning the laser beam on the workpiece at a scanning speed, so that a series of pulse waves of the laser beam form a series of ablation zones along a cutting line and the crystal is damaged. Internal location.

如請求項1所述之方法，其中聚焦該雷射光束係使用一透鏡執行，該透鏡具有一小於約0.5之數值孔徑。 The method of claim 1 wherein focusing the laser beam is performed using a lens having a numerical aperture of less than about 0.5.

如請求項1所述之方法，其中聚焦該雷射光束能提供一延伸景深(depth of field)，以於進入該工件內至少約100微米之一深度造成晶體損傷。 The method of claim 1 wherein focusing the laser beam provides an extended depth of field for entering a depth of at least about 100 microns within the workpiece to cause crystal damage.

如請求項1所述之方法，其中該雷射光束係以進入該工件內之一延伸景深而聚焦於該工件之該表面上。 The method of claim 1 wherein the laser beam is focused on the surface of the workpiece with an extended depth of field entering the workpiece.

如請求項1所述之方法，其中該雷射光束係以進一步進入該工件內之一延伸景深而聚焦於該工件之該表面下方之一焦點偏移(focus offset)處。 The method of claim 1, wherein the laser beam is focused at a focus offset below the surface of the workpiece by further entering an extended depth of field within the workpiece.

如請求項1所述之方法，其中聚焦該雷射光束會引入球面像差(spherical aberration)，該等球面像差具有一縱向球面像差範圍，該縱向球面像差範圍足以將該景深延伸進入該工件中。 The method of claim 1, wherein focusing the laser beam introduces a spherical aberration having a range of longitudinal spherical aberrations sufficient to extend the depth of field into the depth of field In the workpiece.

如請求項18所述之方法，其中該雷射光束係聚焦於該工件之該表面下方之一焦點偏移處。 The method of claim 18, wherein the laser beam is focused at a focus offset below the surface of the workpiece.

如請求項18所述之方法，其中聚焦該雷射光束包含：過度充填具有一衍射受限區域之一透鏡之一孔徑，俾使該等球面像差被引入該衍射受限區域之外。 The method of claim 18, wherein focusing the laser beam comprises: overfilling one of the lenses having one of the diffraction-limited regions, such that the spherical aberration is introduced outside the diffraction-limited region.

如請求項20所述之方法，其中該透鏡被足夠地過度充填，以提供將該景深延伸進入該工件中之該縱向球面像差範圍、同時限制一橫向球面像差範圍。 The method of claim 20, wherein the lens is sufficiently overfilled to provide the range of longitudinal spherical aberration that extends the depth of field into the workpiece while limiting a range of lateral spherical aberration.

如請求項18所述之方法，其中該雷射光束於該工件之該表面上之一光點大小具有一小於約20微米之寬度。 The method of claim 18, wherein the spot size of the laser beam on the surface of the workpiece has a width of less than about 20 microns.

如請求項1所述之方法，其中該雷射光束於該工件之該表面處以處於一約10微米至20微米範圍之一尺寸提供一雷射區，且該工件之該表面處之該燒蝕區小於約10微米。 The method of claim 1, wherein the laser beam provides a laser region at the surface of the workpiece at a size in the range of about 10 microns to 20 microns, and the ablation at the surface of the workpiece The area is less than about 10 microns.

如請求項1所述之方法，更包含：使該雷射光束成形，以於該基板之該表面上形成一可變之細長聚焦光束光點。 The method of claim 1, further comprising: shaping the laser beam to form a variable elongated focused beam spot on the surface of the substrate.

一種用於雷射切割一工件之方法，該方法包含：產生一雷射光束，該雷射光束具有足以於該工件之材料內提供非線性多光子吸收之一波長、一脈波持續時間、及一脈波能量；使用一透鏡聚焦該雷射光束，該透鏡引入具有一縱向球面像差範圍之球面像差，該縱向球面像差範圍足以於該工件內提供一延伸景深(depth of field；DOF)，俾使該雷射光束之單個脈波於該工件內產生一延伸深度虛飾(extended depth affectation)；以及藉由該雷射光束掃描該工件，俾使一系列脈波沿該工件於一系列位置處產生一系列延伸深度虛飾。 A method for laser cutting a workpiece, the method comprising: generating a laser beam having a wavelength sufficient to provide nonlinear multiphoton absorption in a material of the workpiece, a pulse duration, and a pulse wave energy; focusing the laser beam with a lens that introduces a spherical aberration having a range of longitudinal spherical aberrations sufficient to provide an extended depth of field (DOF) within the workpiece And causing a single pulse of the laser beam to generate an extended depth affectation in the workpiece; and scanning the workpiece by the laser beam, causing a series of pulse waves to follow the workpiece A series of extended depth illusions are produced at a range of locations.

如請求項25所述之方法，其中該雷射光束包含複數個超短脈波，該等超短脈波具有一小於1奈秒之脈波持續時間。 The method of claim 25, wherein the laser beam comprises a plurality of ultrashort pulse waves having a pulse duration of less than 1 nanosecond.

如請求項25所述之方法，其中該透鏡包含一衍射受限區域，且聚焦該雷射光束包含過度充填該透鏡之一孔徑，俾使該等球面像差被引入該衍射受限區域之外。 The method of claim 25, wherein the lens comprises a diffraction limited region, and focusing the laser beam comprises overfilling an aperture of the lens such that the spherical aberration is introduced outside the diffraction limited region .

如請求項27所述之方法，其中該透鏡被足夠地過度充填，以提供將該景深延伸進入該工件中之該縱向球面像差範圍、同時限制一橫向球面像差範圍。 The method of claim 27, wherein the lens is sufficiently overfilled to provide the range of longitudinal spherical aberration that extends the depth of field into the workpiece while limiting a range of lateral spherical aberration.

如請求項27所述之方法，其中該雷射光束於該工件之該表面上之一光點大小具有一小於約20微米之寬度。 The method of claim 27, wherein the spot size of the laser beam on the surface of the workpiece has a width of less than about 20 microns.

如請求項29所述之方法，其中該延伸虛飾延伸至該工件中至少100微米。 The method of claim 29, wherein the extended embossing extends into the workpiece by at least 100 microns.

如請求項25所述之方法，其中該透鏡具有一小於約0.5之數值孔徑。 The method of claim 25, wherein the lens has a numerical aperture of less than about 0.5.

如請求項25所述之方法，其中該雷射光束係以一近軸焦點(paraxial focal point)而被聚焦於該工件之該表面上。 The method of claim 25, wherein the laser beam is focused on the surface of the workpiece at a paraxial focal point.

如請求項25所述之方法，其中該雷射光束係以一近軸焦點而被聚焦於該工件之該表面下方之一焦點偏移處。 The method of claim 25, wherein the laser beam is focused at a focus offset below the surface of the workpiece with a paraxial focus.

如請求項25所述之方法，其中該雷射光束被聚焦成使一能量密度足以於一燒蝕區處燒蝕該工件之一表面。 The method of claim 25, wherein the laser beam is focused such that an energy density is sufficient to ablate one surface of the workpiece at an ablation zone.

如請求項25所述之方法，其中該雷射光束以處於一約10微米至20微米範圍之一尺寸於該工件之該表面處提供一雷射區，且該工件之該表面處之該燒蝕區小於約10微米。 The method of claim 25, wherein the laser beam provides a laser region at the surface of the workpiece at a dimension in the range of about 10 microns to 20 microns, and the surface is at the surface of the workpiece. The etched area is less than about 10 microns.

如請求項25所述之方法，其中該材料係為藍寶石，且該波長係處於紫外光(UV)範圍內。 The method of claim 25, wherein the material is sapphire and the wavelength is in the ultraviolet (UV) range.

如請求項25所述之方法，其中該材料係為矽，且該波長係處於紅外光(IR)範圍內。 The method of claim 25, wherein the material is germanium and the wavelength is in the infrared (IR) range.

如請求項25所述之方法，其中該材料係為玻璃，且該波長係處於可見範圍內。 The method of claim 25, wherein the material is glass and the wavelength is Is in the visible range.

如請求項25所述之方法，其中藉由該雷射光束掃描該工件，俾使一系列單個脈波於各自位置處產生該系列延伸深度虛飾。 The method of claim 25, wherein the workpiece is scanned by the laser beam such that the series of individual pulse waves produce the series of extended depth swashes at respective locations.

一種雷射加工系統，包含：一雷射，用於產生一雷射光束，該雷射光束具有足以於該工件之材料內提供非線性多光子吸收之一波長、一脈波持續時間、及一脈波能量；一光束遞送系統，用於聚焦該雷射光束並朝一工件引導該雷射光束，該光束遞送系統包含一擴束器(beam expander)及一透鏡，該擴束器用於擴張該雷射光束，該透鏡用於引入具有一縱向球面像差範圍之球面像差，該縱向球面像差範圍足以於該工件內提供一延伸景深(DOF)，俾使該雷射光束之單個脈波於該工件內產生一延伸虛飾；以及一工件定位台，用於移動該工件以於該工件上掃描該雷射光束，俾使一系列脈波於該工件內形成一系列延伸虛飾。 A laser processing system comprising: a laser for generating a laser beam having a wavelength sufficient for providing nonlinear multiphoton absorption in a material of the workpiece, a pulse duration, and a Pulse wave energy; a beam delivery system for focusing the laser beam and directing the laser beam toward a workpiece, the beam delivery system comprising a beam expander and a lens for expanding the mine a beam for introducing a spherical aberration having a range of longitudinal spherical aberrations sufficient to provide an extended depth of field (DOF) within the workpiece, such that a single pulse of the laser beam is An extension embossing is generated in the workpiece; and a workpiece positioning table is configured to move the workpiece to scan the laser beam on the workpiece, so that a series of pulse waves form a series of extended embossments in the workpiece.

如請求項40所述之雷射加工系統，其中該雷射用以產生具有複數個超短脈波之一雷射光束，該等超短脈波具有一小於1奈秒之脈波持續時間。 The laser processing system of claim 40, wherein the laser is for generating a laser beam having a plurality of ultrashort pulse waves having a pulse duration of less than one nanosecond.

如請求項40所述之雷射加工系統，其中該透鏡具有一小於約0.5之數值孔徑。 The laser processing system of claim 40, wherein the lens has a numerical aperture of less than about 0.5.

如請求項40所述之雷射加工系統，其中該透鏡包含一三元透鏡，該三元透鏡具有一至少約25毫米之焦距以及一小於約0.5之數值孔徑。 The laser processing system of claim 40, wherein the lens comprises a ternary lens having a focal length of at least about 25 millimeters and a numerical aperture of less than about 0.5.