CN1330580A - 激光处理 - Google Patents

激光处理 Download PDF

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CN1330580A
CN1330580A CN99814447A CN99814447A CN1330580A CN 1330580 A CN1330580 A CN 1330580A CN 99814447 A CN99814447 A CN 99814447A CN 99814447 A CN99814447 A CN 99814447A CN 1330580 A CN1330580 A CN 1330580A
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威廉·劳尔
皮埃尔·特里潘尼尔
唐纳德·V·斯玛特
詹姆斯·科丁利
迈克尔·皮洛特金
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General Scanning Inc
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Abstract

本发明提供一种在衬底(22)上蒸发目标结构(24)的系统(10,33)和方法。根据本发明,计算在目标结构(24)中沉积单位能量所需要的入射光束能量作为波长的函数,然后,对于入射光束能量,计算预计沉积在衬底(22)中的能量作为波长的函数。找出对应于预计沉积在衬底(22)中的能量的相对低值的波长,该低值充分地低于在较高波长上预计沉积在衬底中的能量的值。提供一种激光系统(10),配置成在对应于预计沉积在衬底(22)中的能量的相对低值的波长上产生激光输出。在对应于预计沉积在衬底中的能量的相对低值的波长上,将激光输出(13,14,15,16,18 ＆ 20)导向衬底(22)上的目标结构(24),以便蒸发该目标结构(24)。

Description

激光处理
本发明涉及激光处理系统和方法，包括以高产出率去除在集成电路或存储器装置的硅衬底上紧密间隔的金属连接结构或“熔丝”。
激光系统可以用来去除集成电路和存储器装置，诸如ASIC，DRAM，和SRAM中的熔丝结构(“熔固连接”)，用于诸如去除缺陷单元目的和替换缺陷单元为以此目的提供的冗余单元(冗余存储器修复)。连接处理激光系统包括由General Scanning公司制造的M320和M325系统，它们在很多波长上产生激光输出，包括1.047μm、1.064μm和1.32μm。
经济需要导致更小、更复杂、更高密度的半导体结构的开发。这些更小的结构具有在相对高速下工作的优点。同时，由于半导体器件零件可以更小，更多的零件可以包括在一个单独的硅片中。由于在半导体加工设备上处理单个晶片的费用几乎不依赖于晶片上零件的数目，因此每个晶片上更多数目的零件可以转变成每个零件更低的成本。
在80年代，半导体器件零件经常包括多晶硅和硅化物互连。尽管基于多晶硅的互连是相对较差的导体，但他们使用当时的工艺容易制造，并且非常适合于那时普遍使用的Nd：YAG激光器产生的波长。然而，随着几何尺寸的缩小，多晶硅互连和连接结构的较差传导性变成问题，一些半导体制造商转向了铝。已经发现某些常规的激光器它们可以切割多晶硅连接，不能切割铝连接，特别是会发生损坏硅衬底。这种情况可以通过以下事实解释，铝的反射性非常高而吸收性低。因此，必须使用增加的能量以克服这种低吸收性。当使用过多的能量时，更高的能量会倾向于毁坏衬底。
Sun等人的美国专利5,265,114提出了一种“吸收度对比”模型用于选择适当的激光波长以切割铝和其他金属，诸如镍、钨和铂。具体地，该专利描述了选择出一个波长范围，在此范围内硅几乎是透明的，并且金属连接材料的光学吸收特性足以用于要被处理的连接。该专利声称对比与激光波长1.064μm和0.532μm，1.2μm到2.0μm波长范围提供了硅衬底和高传导性连接结构之间的高吸收度对比。
本发明提供一种在衬底上蒸发目标结构的系统和方法。根据本发明，计算在目标结构中沉积单位能量所需要的入射光束能量作为波长的函数。然后，对于入射光束能量，计算预计沉积在衬底中的能量作为波长的函数。找出对应于预计沉积在衬底中的能量的相对低值的波长，该低值充分地低于在较高波长上预计沉积在衬底中的能量的值。提供一种激光系统，配置成在对应于预计沉积在衬底中的能量的相对低值的波长上产生激光输出。在对应于预计沉积在衬底中的能量的相对低值的波长上，将激光输出导向衬底上的目标结构，以便蒸发该目标结构。
本发明的某些应用包括选择合适的波长用于切割金属连接而不对硅衬底产生不可接受的损害。其中波长小于，而不是大于，传统的波长1.047μm和1.064μm。该波长选择方法是有利的，因为使用较短的波长会导致较小的激光点，其它条件相同的情况下，用该激光点只击中需要的连接将更容易。具体地，其它条件相同的情况下，根据公式激光光点大小直接正比于波长：光点尺寸正比于λf，其中λ是激光波长，f是光系统的f数。
此外，本发明的某些应用包括选择合适的波长，在此波长下衬底具有低吸收度，但是互连材料比在常规波长1.047μm和1.064μm或者比常规更高的波长具有更高的吸收度。由于互连材料降低了反射性，入射激光能量可以降低而互连材料仍然吸收足够的能量使互连熔断而不需要多个激光脉冲(这会影响吞吐量)，或者由于激光光束造成附带损害。
本发明可以只用单个激光脉冲对布置为紧密间隔的图案的高传导率互连材料，诸如铜，金等等进行高质量的激光连接切割而不损害衬底。本发明还允许比在波长1.047μm，1.064μm下获得更小的激光点尺寸，而仍然提供可接受的连接切割。
图1是根据本发明用于去除半导体器件的连接的激光器系统的框图，其中该连接由诸如铜或金等材料制成。
图2是半导体器件衬底上的连接的透视图。
图3是铜，金，铝和硅的吸收度作为波长的函数的曲线图。
图4是根据本发明，硅衬底上对于铜，金，和铝连接的衬底吸收函数作为波长的函数的曲线图。
图5是硅衬底上对于铜，金，和铝连接的L-S函数曲线图，其中L是连接的吸收度，S是衬底的吸收度。
图6是硅衬底上对于铜，金，和铝连接的(L－S)/(L＋S)函数曲线图，其中L是连接的吸收度，S是衬底的吸收度。
在图1的框图中，示出了用于消除半导体器件连接的系统。激光器10构成为在常规波长，例如1.047μm上工作。其后排列着激光输出系统，包括波长转换器12，诸如频率加倍器或光学参量振荡器(OPO)，用于转换到波谱“绿”区的小于0.55μm的波长。如下详述，激光束然后通过激光输出系统的剩余部分，包括受控的电—声-光衰减器13，扩展光束的望远装置14，和借助两个扫描电流计18和20通过聚焦透镜16扫描光束的扫描头15。在计算机33的控制下，光点被聚焦到要去除连接24的晶片22上。
激光器10被安置在相对于电流计和工件稳定的平台11上。它从自身外部受计算机33控制将其光束传送至包括精确X和Y电流计18和20的扫描头。在消除连接时光束以小于3/10微米的精度定位是非常重要的。关联于连续移动的电流计的位置的激光脉冲的时间选择是重要的。计算机33在需要时控制发出激光脉冲。
分步重复桌面34移动晶片到位以处理每一半导体器件。
在一个实施方案中，激光器10为钕钒酸盐激光器，其具有总长L约6英寸和短的腔长。
该优选实施方案的转换器12在腔体之外，大约另有4英寸长。在备选实施方案中，激光器10可以配置成产生具有合适波长的激光输出，因此可以不需要转换器。
该激光器为Q开关半导体泵浦激光器，具有足够的长度和结构以便能够通过计算机33以高精度进行脉冲率的外部控制。
激光器的腔体包括部分透射镜7，最优化在钕钒酸盐激光棒6被二极管泵浦的所在波长。部分透射输出镜9也最优化在该波长。
泵浦二极管4根据设计产生一至二瓦功率，它聚焦在激光棒6的后面。如上所述，激光棒在其受泵端，覆以适合于标准激光波长1.064μm或1.047μm的镜7。激光棒的另一端覆以二向色涂层。激光腔中为声光调制器形式的光学Q开关8。它用作建立激光器工作频率的快门。Q开关外面是输出镜9。激光棒受泵端上的镜7和声光Q开关外的镜9这两个镜子组成了激光腔。
另一个声光衰减器形式的系统光学开关13位于激光腔外的激光输出光束中。在计算机33的控制下，它用于除非需要时阻止光束到达电流计，和当需要光束到达电流计时，受控地减小激光束功率到要求的功率水平。在汽化作用过程中，根据系统和工艺的工作参数该功率水平可能小至总激光输出的10％。在汽化作用前激光输出光束对准目标结构的对准过程中，该功率水平可能约为总激光输出的0.1％。
操作中，X，Y电流计10和12的位置通过电流计控制G受控于计算机33。通常，电流计在硅晶片上半导体器件上方以恒定速度移动。激光器基于控制电流计的定时信号而受控于定时信号。激光器以恒定的重复频率工作，并且通过系统光学开关13而与电流计同步。
在图1的框图中，示出了激光束聚焦在晶片上。在图2的放大图中，看到激光束聚焦在半导体器件的连接部件25上。
金属连接通过二氧化硅绝缘层32被支持在硅衬底30上。绝缘层可以是例如0.3-0.5微米厚。在该金属连接之上是另一个二氧化硅层(未示出)。在连接熔断技术中，激光束对接在连接处并将其加热到熔点。在加热过程中，金属由于叠加的氧化物层的约束效果被阻止蒸发。在短脉冲的持续时间内，激光束累积地加热金属直到金属膨胀得将绝缘材料击穿。此时，熔融材料在如此高压下瞬时蒸发并通过击穿孔彻底熔断。
确定由波长转换器12产生的波长需要通过均衡地考虑要处理的互连或连接的值和衬底的值，使得不合需要的沉积于衬底的能量相对于切割连接所需的沉积于连接结构的能量达到折衷。因此，选择波长的准则是不要求衬底非常透明，当对衬底非常透明的波长区域远小于沉积于连接结构的能量的最佳区域时，这尤其重要。
选择合适波长的准则如下：
1)计算在连接结构上沉积单位能量所需的相对入射激光束能量。该相对入射激光束能量正比于连接结构的吸收度(absorption)的倒数。例如，如果连接结构具有吸收度0.333，则它沉积在连接结构上相同的能量比具有吸收度为1的结构需要三倍的入射激光能量。图3示出了铜、金、铝和硅的吸收度作为波长的函数(铜、金和铝是可能的的连接结构材料，硅是衬底材料)。
2)用步骤(1)中计算出的入射光束能量，计算沉积在衬底中的能量。对于完好对准的光点，该能量正比于步骤(1)中计算出的入射能量，减去连接结构吸收的能量，乘以衬底的吸收度。即衬底吸收的能量正比于(1/L－1)×S(在此为“衬底吸收函数”)，其中L为连接结构吸收度，S为衬底吸收度。
3)找出步骤(2)中确定的衬底吸收函数的低值作为激光波长的函数。
图4示出了在硅衬底上对于铜、金和铝，衬底吸收函数作为波长的函数，波长范围在0.3-1.4μm。衬底吸收函数的值可以从如图3所示的吸收曲线推出，考虑到确定性，使用的任一个比例常数(见上述步骤(2))选择为0.5(该常数仅改变图4的垂直比例，而不改变由此得出的任何结论)。
由图4看出，对于金和铜的结构(不包括铝)，在大致小于0.55μm的波长区域中，其衬底吸收函数与波长大于1.2μm的区域中的衬底吸收函数可相比拟。
还注意到该函数与如图5和6表示的函数相比很不相同，图5和6示出了代表简单吸收对比度的两种可能的函数。具体地，图5示出了函数L－S，用百分比表示，图6示出了函数(L－S)/(L＋S)。在每种情况下，根据图5和6，即使对于金或铜的连接结构，小于0.55μm的波长区域发现不合要求，因为图中所示函数在该区域小于零。该负值反映了这样的事实，即在该波长区域，衬底比连接结构更具吸收性，于是，根据此模型，该波长区域不应选择。

Claims (25)

1.一种在衬底上蒸发目标结构的方法，包括如下步骤：
计算在目标结构中沉积单位能量所需要的入射光束能量，作为波长的函数；
对于入射光束能量，计算预计沉积在衬底中的能量作为波长的函数；
找出对应于预计沉积在衬底中的能量的相对低值的波长，该低值充分地低于在较高波长上预计沉积在衬底中的能量的值；
提供一种激光系统，配置成在对应于预计沉积在衬底中的能量的相对低值的波长上产生激光输出；以及
在对应于预计沉积在衬底中的能量的相对低值的波长上，将激光输出导向衬底上的目标结构，以便蒸发该目标结构。
2.根据权利要求1的方法，其中对应于预计沉积在衬底中的能量的相对低值的波长充分地小于1.047μm。
3.根据权利要求2的方法，其中对应于预计沉积在衬底中的能量的相对低值的波长小于0.55μm。
4.根据权利要求3的方法，其中目标结构包括传导率大于铝的金属。
5.根据权利要求4的方法，其中金属包括铜。
6.根据权利要求4的方法，其中金属包括金。
7.根据权利要求4的方法，其中衬底包括硅。
8.根据权利要求1的方法，其中衬底上的目标结构包括半导体器件的连接。
9.根据权利要求8的方法，其中半导体器件包括集成电路。
10.根据权利要求8的方法，其中半导体器件包括存储器装置。
11.根据权利要求1的方法，其中预计沉积在衬底中的能量基本上正比于在目标结构中沉积单位能量所需要的入射光束能量减去沉积在目标结构中的能量乘以衬底的吸收度。
12.一种在衬底上蒸发目标结构的系统，包括：
激光泵浦源；
激光谐振腔，配置成被该激光泵浦源泵浦；以及
激光输出系统，给出在目标结构中沉积单位能量所需要的入射光束能量，配置成在对应于预计沉积在衬底中的能量的相对低值的波长上，从激光谐振腔中储存的能量产生出激光输出，并将激光输出导向衬底上的目标结构以便蒸发目标结构，该低值充分地低于在较高波长上预计沉积在衬底中的能量的值。
13，根据权利要求12的系统，其中激光输出系统包括波长转换器。
14，根据权利要求12的系统，其中激光谐振腔产生在对应于预计沉积在衬底中的能量的相对低值的波长上的激光辐射。
15.根据权利要求12的系统，其中对应于预计沉积在衬底中的能量的相对低值的波长充分地小于1.047μm。
16.根据权利要求15的系统，其中对应于预计沉积在衬底中的能量的相对低值的波长小于0.55μm。
17.根据权利要求16的系统，其中目标结构包括传导率大于铝的金属。
18.根据权利要求17的系统，其中金属包括铜。
19.根据权利要求17的系统，其中金属包括金。
20.根据权利要求17的系统，其中衬底包括硅。
21.根据权利要求14的系统，其中衬底上的目标结构包括半导体器件的连接。
22.根据权利要求21的系统，其中半导体器件包括集成电路。
23.根据权利要求21的系统，其中半导体器件包括存储器装置。
24.根据权利要求14的系统，其中预计沉积在衬底中的能量基本上正比于在目标结构中沉积单位能量所需要的入射光束能量减去沉积在目标结构中的能量乘以衬底的吸收度。
25.一种在衬底上蒸发目标结构的方法，包括如下步骤：
提供一种激光系统，给出在目标结构中沉积单位能量所需要的入射光束能量，配置成在对应于预计沉积在衬底中的能量的一个相对低值的波长上产生激光输出，该低值充分地低于在较高波长上预计沉积在衬底中的能量的值；以及
在对应于预计沉积在衬底中的能量的相对低值的波长上，将激光输出导向衬底上的目标结构以便蒸发该目标结构。
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102097529A (zh) * 2010-11-05 2011-06-15 张立国 一种紫外激光薄膜太阳能电池清边方法

Families Citing this family (45)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5998759A (en) * 1996-12-24 1999-12-07 General Scanning, Inc. Laser processing
US6300590B1 (en) * 1998-12-16 2001-10-09 General Scanning, Inc. Laser processing
US6281471B1 (en) 1999-12-28 2001-08-28 Gsi Lumonics, Inc. Energy-efficient, laser-based method and system for processing target material
US8217304B2 (en) * 2001-03-29 2012-07-10 Gsi Group Corporation Methods and systems for thermal-based laser processing a multi-material device
US7838794B2 (en) 1999-12-28 2010-11-23 Gsi Group Corporation Laser-based method and system for removing one or more target link structures
US7723642B2 (en) * 1999-12-28 2010-05-25 Gsi Group Corporation Laser-based system for memory link processing with picosecond lasers
US20040134894A1 (en) * 1999-12-28 2004-07-15 Bo Gu Laser-based system for memory link processing with picosecond lasers
US20030222324A1 (en) * 2000-01-10 2003-12-04 Yunlong Sun Laser systems for passivation or link processing with a set of laser pulses
US20060141681A1 (en) * 2000-01-10 2006-06-29 Yunlong Sun Processing a memory link with a set of at least two laser pulses
US7671295B2 (en) * 2000-01-10 2010-03-02 Electro Scientific Industries, Inc. Processing a memory link with a set of at least two laser pulses
WO2002018090A1 (fr) * 2000-08-29 2002-03-07 Mitsubishi Denki Kabushiki Kaisha Appareil d'usinage laser
US8497450B2 (en) * 2001-02-16 2013-07-30 Electro Scientific Industries, Inc. On-the fly laser beam path dithering for enhancing throughput
US20070173075A1 (en) * 2001-03-29 2007-07-26 Joohan Lee Laser-based method and system for processing a multi-material device having conductive link structures
US20030129396A1 (en) * 2001-12-27 2003-07-10 Gerhard Kiessling Coating composition for metal conductors and coating process involving the use thereof
US6951995B2 (en) 2002-03-27 2005-10-04 Gsi Lumonics Corp. Method and system for high-speed, precise micromachining an array of devices
JP2003320466A (ja) * 2002-05-07 2003-11-11 Disco Abrasive Syst Ltd レーザビームを使用した加工機
US20040144760A1 (en) * 2002-05-17 2004-07-29 Cahill Steven P. Method and system for marking a workpiece such as a semiconductor wafer and laser marker for use therein
JP2006502006A (ja) * 2002-10-04 2006-01-19 エレクトロ サイエンティフィック インダストリーズ インコーポレーテッド 超小型部品用搬送具の弾性マスクに正確な寸法のスロットを形成する方法
JP2004200221A (ja) * 2002-12-16 2004-07-15 Toray Eng Co Ltd レーザマーキング方法及び装置
US6947454B2 (en) * 2003-06-30 2005-09-20 Electro Scientific Industries, Inc. Laser pulse picking employing controlled AOM loading
US7616669B2 (en) * 2003-06-30 2009-11-10 Electro Scientific Industries, Inc. High energy pulse suppression method
DE50308288D1 (de) * 2003-12-04 2007-11-08 Festo Ag & Co Mikrowellenwegmesssystem für elektrodynamischen Direktantrieb
KR100462358B1 (ko) * 2004-03-31 2004-12-17 주식회사 이오테크닉스 폴리곤 미러를 이용한 레이저 가공장치
US7923306B2 (en) * 2004-06-18 2011-04-12 Electro Scientific Industries, Inc. Semiconductor structure processing using multiple laser beam spots
US8383982B2 (en) * 2004-06-18 2013-02-26 Electro Scientific Industries, Inc. Methods and systems for semiconductor structure processing using multiple laser beam spots
US8148211B2 (en) * 2004-06-18 2012-04-03 Electro Scientific Industries, Inc. Semiconductor structure processing using multiple laser beam spots spaced on-axis delivered simultaneously
US7935941B2 (en) * 2004-06-18 2011-05-03 Electro Scientific Industries, Inc. Semiconductor structure processing using multiple laser beam spots spaced on-axis on non-adjacent structures
US20060000814A1 (en) 2004-06-30 2006-01-05 Bo Gu Laser-based method and system for processing targeted surface material and article produced thereby
US7372878B2 (en) * 2004-08-06 2008-05-13 Electro Scientific Industries, Inc. Method and system for preventing excessive energy build-up in a laser cavity
US7227098B2 (en) * 2004-08-06 2007-06-05 Electro Scientific Industries, Inc. Method and system for decreasing the effective pulse repetition frequency of a laser
DE102004053298B4 (de) * 2004-08-26 2008-10-09 ARGES Gesellschaft für Industrieplanung und Lasertechnik m.b.H. Scankopf als Teil einer Laser Bohr- und Schneideinrichtung
US7378288B2 (en) * 2005-01-11 2008-05-27 Semileds Corporation Systems and methods for producing light emitting diode array
US8290239B2 (en) * 2005-10-21 2012-10-16 Orbotech Ltd. Automatic repair of electric circuits
JP5203573B2 (ja) * 2006-03-23 2013-06-05 ミヤチテクノス株式会社 レーザ加工装置
US8198566B2 (en) * 2006-05-24 2012-06-12 Electro Scientific Industries, Inc. Laser processing of workpieces containing low-k dielectric material
US8084706B2 (en) * 2006-07-20 2011-12-27 Gsi Group Corporation System and method for laser processing at non-constant velocities
KR20090104001A (ko) * 2007-01-05 2009-10-05 지에스아이 그룹 코포레이션 멀티 펄스 레이저 처리 시스템 및 방법
KR101516742B1 (ko) * 2007-09-19 2015-05-04 엘렉트로 사이언티픽 인더스트리즈 인코포레이티드 고속 빔 편향 링크 가공
US8178818B2 (en) * 2008-03-31 2012-05-15 Electro Scientific Industries, Inc. Photonic milling using dynamic beam arrays
US7982160B2 (en) * 2008-03-31 2011-07-19 Electro Scientific Industries, Inc. Photonic clock stabilized laser comb processing
GB0900036D0 (en) * 2009-01-03 2009-02-11 M Solv Ltd Method and apparatus for forming grooves with complex shape in the surface of apolymer
KR20120113245A (ko) * 2009-12-30 2012-10-12 지에스아이 그룹 코포레이션 고속 빔 편향을 이용한 링크 처리
CN102133687A (zh) * 2010-01-26 2011-07-27 豪晶科技股份有限公司 激光加工装置
CN104159697B (zh) 2011-07-05 2017-02-15 伊雷克托科学工业股份有限公司 在使用过程中为声光射束偏转器和声光调制器提供温度稳定性的系统和方法
US10562132B2 (en) * 2013-04-29 2020-02-18 Nuburu, Inc. Applications, methods and systems for materials processing with visible raman laser

Family Cites Families (60)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US487850A (en) * 1892-12-13 Shaded lamp-chimney
US3740523A (en) * 1971-12-30 1973-06-19 Bell Telephone Labor Inc Encoding of read only memory by laser vaporization
BE794202A (fr) * 1972-01-19 1973-05-16 Intel Corp Liaison fusible pour circuit integre sur substrat semi-conducteur pour memoires
US3941973A (en) * 1974-06-26 1976-03-02 Raytheon Company Laser material removal apparatus
US4044222A (en) * 1976-01-16 1977-08-23 Western Electric Company, Inc. Method of forming tapered apertures in thin films with an energy beam
US4399345A (en) * 1981-06-09 1983-08-16 Analog Devices, Inc. Laser trimming of circuit elements on semiconductive substrates
US4483005A (en) * 1981-09-24 1984-11-13 Teradyne, Inc. Affecting laser beam pulse width
US4535219A (en) * 1982-10-12 1985-08-13 Xerox Corporation Interfacial blister bonding for microinterconnections
US4713518A (en) 1984-06-08 1987-12-15 Semiconductor Energy Laboratory Co., Ltd. Electronic device manufacturing methods
EP0165685B1 (en) * 1984-06-20 1992-09-23 Gould Inc. Laser-based system for the total repair of photomasks
USRE34192E (en) * 1985-05-01 1993-03-09 Spectra-Physics, Laser Diode Systems, Inc. Miniaturized Q-switched diode pumped solid state laser
JPS6286851A (ja) 1985-10-14 1987-04-21 Nec Corp レ−ザ−トリミング装置
US4823320A (en) * 1986-05-08 1989-04-18 Texas Instruments Incorporated Electrically programmable fuse circuit for an integrated-circuit chip
US4752455A (en) * 1986-05-27 1988-06-21 Kms Fusion, Inc. Pulsed laser microfabrication
US5022040A (en) * 1986-05-30 1991-06-04 Hughes Aircraft Company Upconversion pumped lasers
US4705698A (en) 1986-10-27 1987-11-10 Chronar Corporation Isolation of semiconductor contacts
US4847850A (en) * 1986-12-23 1989-07-11 Spectra-Physics, Inc. Continuum generation with miniaturized Q-switched diode pumped solid state laser
US4853758A (en) 1987-08-12 1989-08-01 American Telephone And Telegraph Company, At&T Bell Laboratories Laser-blown links
US5070392A (en) * 1988-03-18 1991-12-03 Digital Equipment Corporation Integrated circuit having laser-alterable metallization layer
US5059764A (en) * 1988-10-31 1991-10-22 Spectra-Physics, Inc. Diode-pumped, solid state laser-based workstation for precision materials processing and machining
US5225924A (en) * 1989-04-07 1993-07-06 Dainippon Screen Mfg. Co., Ltd. Optical beam scanning system
US5025300A (en) * 1989-06-30 1991-06-18 At&T Bell Laboratories Integrated circuits having improved fusible links
IL91240A (en) * 1989-08-07 1994-07-31 Quick Tech Ltd Pulsed laser apparatus and systems and techniques for its operation
US5008512A (en) * 1989-09-08 1991-04-16 Microelectronics And Computer Technology Corporation Method of laser bonding electrical members
US5021362A (en) * 1989-12-29 1991-06-04 At&T Bell Laboratories Laser link blowing in integrateed circuit fabrication
US5066291A (en) * 1990-04-25 1991-11-19 Cincinnati Sub-Zero Products, Inc. Solid-state laser frequency conversion system
US5241212A (en) * 1990-05-01 1993-08-31 Mitsubishi Denki Kabushiki Kaisha Semiconductor device having a redundant circuit portion and a manufacturing method of the same
JP3150322B2 (ja) * 1990-05-18 2001-03-26 株式会社日立製作所 レーザによる配線切断加工方法及びレーザ加工装置
DE4203804C2 (de) 1991-03-22 1994-02-10 Siemens Ag Verfahren zur Herstellung von Kontakten auf einer mit einer UV-transparenten Isolationsschicht bedeckten leitenden Struktur in höchstintegrierten Schaltkreisen
US5268911A (en) * 1991-07-10 1993-12-07 Young Eddie H X-cut crystal quartz acousto-optic modulator
US5293025A (en) * 1991-08-01 1994-03-08 E. I. Du Pont De Nemours And Company Method for forming vias in multilayer circuits
US5163062A (en) * 1991-10-16 1992-11-10 The United States Of America As Represented By The Secretary Of The Navy Method of frequency shifting using a chromium doped laser transmitter
US5235154A (en) * 1992-04-28 1993-08-10 International Business Machines Corporation Laser removal of metal interconnects
US5323053A (en) * 1992-05-28 1994-06-21 At&T Bell Laboratories Semiconductor devices using epitaxial silicides on (111) surfaces etched in (100) silicon substrates
US5265114C1 (en) 1992-09-10 2001-08-21 Electro Scient Ind Inc System and method for selectively laser processing a target structure of one or more materials of a multimaterial multilayer device
US5525831A (en) 1993-04-05 1996-06-11 Nippondenso Co., Ltd. Semiconductor device with thin film resistor having reduced film thickness sensitivity during trimming process
JPH0714853A (ja) * 1993-06-18 1995-01-17 Fujitsu Ltd シリコン基板上の化合物半導体装置とその製造方法
US5453594A (en) * 1993-10-06 1995-09-26 Electro Scientific Industries, Inc. Radiation beam position and emission coordination system
JP2590710B2 (ja) * 1993-11-26 1997-03-12 日本電気株式会社 半導体装置およびその製造方法
US5611946A (en) * 1994-02-18 1997-03-18 New Wave Research Multi-wavelength laser system, probe station and laser cutter system using the same
US5521932A (en) * 1994-05-03 1996-05-28 Light Solutions Corporation Scalable side-pumped solid-state laser
US5685995A (en) 1994-11-22 1997-11-11 Electro Scientific Industries, Inc. Method for laser functional trimming of films and devices
US5696778A (en) * 1995-05-09 1997-12-09 Ophir Corporation Method of and apparatus for generating intracavity double raman shifted laser pulses
US6007963A (en) * 1995-09-21 1999-12-28 Sandia Corporation Method for extreme ultraviolet lithography
US5760674A (en) * 1995-11-28 1998-06-02 International Business Machines Corporation Fusible links with improved interconnect structure
JP3396356B2 (ja) * 1995-12-11 2003-04-14 三菱電機株式会社 半導体装置，及びその製造方法
US6287900B1 (en) * 1996-08-13 2001-09-11 Semiconductor Energy Laboratory Co., Ltd Semiconductor device with catalyst addition and removal
US6103992A (en) * 1996-11-08 2000-08-15 W. L. Gore & Associates, Inc. Multiple frequency processing to minimize manufacturing variability of high aspect ratio micro through-vias
US5998759A (en) * 1996-12-24 1999-12-07 General Scanning, Inc. Laser processing
US6025256A (en) 1997-01-06 2000-02-15 Electro Scientific Industries, Inc. Laser based method and system for integrated circuit repair or reconfiguration
US6057221A (en) * 1997-04-03 2000-05-02 Massachusetts Institute Of Technology Laser-induced cutting of metal interconnect
KR100228533B1 (ko) * 1997-06-23 1999-11-01 윤종용 반도체 집적회로의 용단가능한 퓨즈 및 그 제조방법
US5968847A (en) * 1998-03-13 1999-10-19 Applied Materials, Inc. Process for copper etch back
US6057180A (en) 1998-06-05 2000-05-02 Electro Scientific Industries, Inc. Method of severing electrically conductive links with ultraviolet laser output
US6339604B1 (en) * 1998-06-12 2002-01-15 General Scanning, Inc. Pulse control in laser systems
US6181728B1 (en) * 1998-07-02 2001-01-30 General Scanning, Inc. Controlling laser polarization
US6144118A (en) * 1998-09-18 2000-11-07 General Scanning, Inc. High-speed precision positioning apparatus
KR100294346B1 (ko) * 1998-11-07 2001-07-12 허인구 제거가능한 토목용 앵커
US6300590B1 (en) * 1998-12-16 2001-10-09 General Scanning, Inc. Laser processing
US6172325B1 (en) * 1999-02-10 2001-01-09 Electro Scientific Industries, Inc. Laser processing power output stabilization apparatus and method employing processing position feedback

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102097529A (zh) * 2010-11-05 2011-06-15 张立国 一种紫外激光薄膜太阳能电池清边方法

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US20030189032A1 (en) 2003-10-09
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AU2363800A (en) 2000-07-03
WO2000035623A1 (en) 2000-06-22

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