JP2004306101A - Apparatus and method for laser beam machining - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus which can select two or more works at a time among many aligned works to be processed and selectively apply machining, which improves work efficiency on the workpieces and can shorten the processing time, while simplifying the apparatus, keeping a minimum spot diameter small even in the case of a pitch change in a number of aligned works and without deterioration of quality of the spot. <P>SOLUTION: The apparatus comprises a laser beam source 14, a stage 10 movably carrying the workpiece 1 on it, an optical system 9 to diverge the laser beam emitted from the laser beam source 14 into a plurality of beams, and then to converge them to irradiate the workpiece 1, a shutter 6 capable of opening and closing to each optical pass of a plurality of diverged laser beams 12, 13, and beam shifting means 7, 8 which can shift a plurality of diverged laser beams 12, 13 in a relatively independent manner and adjust the irradiation point of the laser beams 12, 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

一方、この実施の形態では、２本のレーザビーム１２、１３を用いて２本のヒューズ１を同時に加工し得るため、最小照射時間は従来（図４）の２倍となり、処理速度も２倍となる。例えば、レーザの発振周波数が１０ｋＨｚであり、最小切断ヒューズ間隔が５μｍのとき、従来の処理速度は５０ｍｍ／秒となるが、この実施の形態では、１００ｍｍ／秒となる。
【００２９】
現在の半導体デバイスにおけるヒューズ１の間隔ｄは、２μｍから１０μｍが一般的であり、上記２つのレーザビーム１２、１３の間隔は最大でもその数倍を見込めばよく、間隔の最大調整可能範囲は５０μｍで十分となる。この実施の形態では、微小な光軸調整しか必要としないため、ガルバノミラー７、８の角度変化も微小となる。また、レーザビームの照射位置を調整可能とすることにより、ヒューズ１に対する正確な位置合わせが可能となり、照射範囲を最大限絞っても確実にヒューズ１にレーザビームを照射することができるという側面もある。このため、小径の集光レンズ９が使用でき、また、テレセントリック光学系を使用した集光レンズ９において、最小スポット径を小さく保つことが可能となる。テレセントリック光学系とは、入射ビームが角度を持っていてもレンズから出る出射ビームは垂直となるような光学系をいう。
【００３０】
以上のように、本発明の第１の実施の形態に係るレーザ加工装置では、レーザ光源からのレーザビームを複数に分岐した後、集光してヒューズ１に照射する光学系を有している。従って、一つのレーザ光源で２つの主及び副レーザビーム１２、１３を照射し得る。装置を簡略化できるとともに、２以上のヒューズ１を同時に加工することが可能である。これにより、加工効率の向上を図ることができる。
【００３１】
また、分岐された２つの主及び副レーザビーム１２、１３のうち、少なくとも１つのレーザビーム１２又は１３の照射位置をそれぞれ独立に調整し得るビーム移動手段７、８を有している。従って、多数並ぶヒューズ１のピッチの変化に対しても、少なくとも１以上のレーザビーム１２、１３の照射位置を変えることにより、同時加工するヒューズ１相互への照射位置を正確に合わせることができる。このため、最小スポット径を小さく保ち、かつスポット品質を落とすことなく、複数のヒューズ１の配列方向と間隔に合わせて２以上のヒューズ１を同時に加工することが可能となる。
【００３２】
さらに、分岐された２つの主及び副レーザビームのそれぞれの光路に対して開閉が可能なシャッタ６を備えているため、２以上のヒューズ１を同時に選び、かつ対象となる２以上のヒューズ１のうちから加工すべきヒューズ１を選択して加工することが可能となる。
【００３３】
さらに、複数のヒューズ１を載置したＸ−Ｙステージ１０を移動させることにより、Ｘ−Ｙステージ１０上の全部のヒューズ１に対して、順次かつ迅速に加工を行うことができる。
【００３４】
（レーザ加工方法）
次に、上記レーザ加工装置を用いたレーザ加工方法について説明する。
【００３５】
まず、図２のような、半導体チップ３の上に複数のヒューズ（被加工物）１がＸ方向及びＹ方向にそれぞれ等間隔ｄで配列された半導体基板２をＸ−Ｙステージ１０上の基板チャック１１に固定する。
【００３６】
次いで、シャッタ６によりレーザビームの光路を閉じた状態で、レーザ光源１４からレーザビームを発生させる。半導体基板２上でのヒューズ１の位置情報に基づいて、Ｘ、Ｙガルバノミラー７、８の角度を調整する。この場合、まず、Ｘ方向に間隔ｄで配列された第１番目及び第２番目のヒューズ１に対して位置合わせする。
【００３７】
次に、シャッタ６を開けて、２分岐したレーザビームを集光レンズ９により集光させて主レーザビーム１２及び副レーザビーム１３を形成し、それぞれＸ方向に配列された第１番目及び第２番目のヒューズ１に照射する。その結果、図３に示すように、レーザパルスによる瞬時のエネルギ付与で、Ｘ方向に配列された第１番目及び第２番目のヒューズ１が切断する。なお、位置合わせからヒューズの切断までを断続的な動きの中で行なうこともできるし、ヒューズの動きを適当なスピードに設定することにより位置合わせからヒューズの切断までを連続的な動きの中で行なうこともできる。
【００３８】
次いで、シャッタ６を閉じた後、Ｘ−Ｙステージ１０をＸ方向に距離２ｄだけ移動させて、第３番目及び第４番目のヒューズ１に対して位置合わせする。
【００３９】
次に、予めセットされた加工情報に基づき、第４番目のヒューズ１へのレーザビームの照射が可能なシャッタ６を開けて、レーザビームを集光レンズ９により集光させて副レーザビーム１３だけを形成し、Ｘ方向に配列された第４番目のヒューズ１に照射する。所定の時間の後、図３に示すように、第４番目のヒューズ１が切断する。
【００４０】
このようにして、Ｘ−Ｙステージ１０をＸ方向に距離２ｄずつ移動させてＸ方向に配列されたヒューズ１に対して、図３に示すように順次レーザ加工する。
【００４１】
次に、Ｙ方向に配列されたヒューズ１に対して加工を行なう。
【００４２】
まず、シャッタ６によりレーザビームの光路を閉じた状態で、レーザ光源１４からレーザビームを発生させる。半導体基板２上でのヒューズ１の位置情報に基づいて、Ｘ、Ｙガルバノミラー７、８の角度を調整する。この場合、Ｙ方向に間隔ｄで配列された第１番目及び第２番目のヒューズ１に対して位置合わせする。
【００４３】
次に、シャッタ６を開けて、２分岐したレーザビームを集光レンズ９により集光させて主レーザビーム１２及び副レーザビーム１３を形成し、それぞれＹ方向に配列された第１番目及び第２番目のヒューズ１に照射する。所定の時間の後、Ｙ方向に配列された第１番目及び第２番目のヒューズ１が溶断する。
【００４４】
以降、上記と同様にして、Ｘ−Ｙステージ１０をＹ方向に隣接するヒューズの間隔ｄの２倍の距離２ｄずつ移動させてＹ方向に配列されたヒューズ１に対して順次レーザ加工を行う。
【００４５】
以上のように、この発明の第１の実施の形態のレーザ加工方法によれば、レーザ光源１４からのレーザビームを複数に分岐した後、分岐したレーザビームを集光して主レーザビーム１２と副レーザビーム１３を形成し、それぞれヒューズ１に照射している。従って、複数のヒューズ１の同時加工が可能である。これにより、加工効率の向上を図ることができる。
【００４６】
また、分岐された２本の主及び副レーザビーム１２、１３のうち、副レーザビーム１３の照射位置を調整し、主及び副レーザビーム１２、１３をそれぞれ隣接するヒューズ１の位置に位置合わせしている。従って、多数並ぶヒューズ１のピッチの変化に対しても、同時加工するヒューズ１相互への照射位置を正確に合わせることができる。このため、最小スポット径を小さく保ったまま、２つのヒューズ１に対して、同時に加工することが可能となる。
【００４７】
さらに、分岐された２つのレーザビームのそれぞれの光路に対して開閉が可能なシャッタ６を備えているため、隣接する２つのヒューズ１を同時に選び、かつ対象となる２つのヒューズのうちから加工すべきヒューズを選択して加工し、或いはともに加工しないようにすることが可能となる。
【００４８】
さらに、複数のヒューズ１が形成された半導体基板２を載置したステージ１０を所定のインタバルｄｘ又はｄｙずつ移動させることにより、半導体基板２上の全部のヒューズ１に対して、順次かつ迅速に行うことができる。
【００４９】
（第２の実施の形態）
（レーザ加工装置）
図５は、第２の実施の形態に係るレーザ加工装置の構成を示す模式図である。
【００５０】
そのレーザ加工装置は、図５に示すように、第１の実施の形態のレーザ加工装置に偏光切り換え素子１６を追加したものである。レーザ光源１４からの光を円偏光板１５で、一旦、円偏光に変更したあと、２分岐したレーザビームの光路のそれぞれに挿入した偏光切換え素子１６により、各レーザビームを自由な方向に偏光可能となっている。
【００５１】
ヒューズ１の方向とレーザビームの偏光方向を平行にすることにより、レーザビームのエネルギを集中させて微細化するヒューズ１の切断をより確実に行うことができる場合がある。このような場合に、第２の実施の形態に係るレーザ加工装置は有用である。
【００５２】
また、半導体デバイスによっては、偏光方向をヒューズ１に垂直又は斜めにした場合に良好な切断が可能となる場合もある。また、ヒューズ１の長手方向がＸ、Ｙ両方向に配置されている場合、一方のレーザビームの偏光をＸ方向に、もう一方をＹ方向に合わせ、各レーザビームをヒューズ１の方向に合わせて選択して使用すれば、両方向のヒューズ１を効率良く切断することが可能となる。
【００５３】
以上のように、この発明の第２の実施の形態のレーザ加工装置によれば、偏光切り換え素子１６を備えているので、ヒューズ１が切断し易い方向に各レーザビームの偏光方向を合わせて照射することにより、レーザビームのエネルギを集中させて各方向のヒューズ１に対して効率良く切断を行なうことが可能となる。
【００５４】
（レーザ加工方法）
次に、この発明の第２の実施の形態に係るレーザ加工装置を用いたレーザ加工方法について図５を参照して説明する。
【００５５】
まず、図５に示すＸ−Ｙステージ１０上の基板チャック１１に半導体基板２を固定する。
【００５６】
最初に、Ｘ方向に間隔ｄで配列されたヒューズ１に対して加工を行なう。この場合、シャッタ６によりレーザビームの光路を閉じた状態で、レーザ光源１４からレーザビームを発生させる。半導体基板２上でのヒューズ１の位置情報に基づいて、Ｘ、Ｙガルバノミラー７、８の角度を調整する。この場合、まず、Ｘ方向に間隔ｄで配列された第１番目及び第２番目のヒューズ１に対して位置合わせする。
【００５７】
次に、シャッタ６を開ける。この場合、レーザビームは円偏光素子１５により円偏光されたのち、全反射ミラー４により反射されてビームスプリッタ５に入射する。２分岐したレーザビームのうち、一方は偏光切換え素子１６及び集光レンズ９を順に透過し、主レーザビーム１２を形成する。他方は、偏光切換え素子１６を透過し、全反射ミラー４により反射されてＸ、Ｙガルバノミラー７、８に順次入射する。Ｘ、Ｙガルバノミラー７、８を透過したレーザビームは照射位置が調整されて集光レンズ９を透過し、副レーザビーム１３を形成する。偏光切換え素子１６により、例えば細長いヒューズ１の場合ヒューズ１の長手方向に対して切断しやすい方向に主及び副レーザビーム１２、１３の偏光方向を合わせる。この場合、加工すべきヒューズ１はすべてＸ方向に配列されているので、主及び副レーザビーム１２、１３について同じ偏光方向に設定する。
【００５８】
このようにして形成した主及び副レーザビーム１２、１３をＸ方向に配列された第１番目及び第２番目のヒューズ１に照射する。所定の時間の後、Ｘ方向に配列された第１番目及び第２番目のヒューズ１が溶断する。
【００５９】
次いで、シャッタ６を閉じた後、Ｘ−Ｙステージ１０をＸ方向にヒューズの隣接間隔ｄの２倍の距離２ｄだけ移動させて、第３番目及び第４番目のヒューズ１に対して位置合わせし、第１の実施の形態と同様にしてレーザ加工を行なう。
【００６０】
このようにして、Ｘ−Ｙステージ１０をＸ方向に距離２ｄずつ移動させて、Ｘ方向に配列されたヒューズ１に対して順次、同時に２つずつ隣接ヒューズ１を選び、それらに対して選択的に加工する。
【００６１】
次に、Ｙ方向に間隔ｄで配列されたヒューズ１に対して加工を行なう。まず、Ｘ方向に配列されたヒューズ１に対して加工を行なった場合と同様にして、Ｙ方向に間隔ｄで配列された第１番目及び第２番目のヒューズ１に対して位置合わせする。
【００６２】
次に、Ｘ方向に配列されたヒューズ１に対して加工を行なった場合と同様にして、偏光切換え素子１６により、ヒューズ１が切断し易い方向に合わせて主及び副レーザビーム１２、１３の偏光方向を設定する。この場合、加工すべきヒューズ１はすべてＹ方向に配列されているので、Ｘ方向に配列されたヒューズ１に対して加工を行なった場合に対して例えば直交する方向に主及び副レーザビーム１２、１３の偏光方向を設定する。かつ、ここで、加工対象とすべきヒューズ１はすべてＹ方向に配列されているので、主及び副レーザビーム１２、１３について同じ偏光方向に設定する。このようにして形成した主及び副レーザビーム１２、１３をＹ方向に配列された第１番目及び第２番目のヒューズ１に照射する。所定の時間の後、Ｙ方向に配列された第１番目及び第２番目のヒューズ１が溶断する。
【００６３】
以降、上記と同様にして、Ｘ−Ｙステージ１０をＹ方向に距離２ｄずつ移動させて、Ｙ方向に配列されたヒューズ１に対して順次、同時に２つずつ隣接ヒューズ１を選び、それらに対して選択的にレーザ加工を行う。
【００６４】
以上のように、第２の実施の形態のレーザ加工方法によれば、ヒューズ１が切断し易い方向に合わせてレーザビーム１２、１３の偏光方向を切り換えている。このため、レーザビーム１２、１３のエネルギを集中させることができるので、ヒューズ１の切断を効率よく行うことができる。
【００６５】
以上、実施の形態によりこの発明を詳細に説明したが、この発明の範囲は上記実施の形態に具体的に示した例に限られるものではなく、この発明の要旨を逸脱しない範囲の上記実施の形態の変更はこの発明の範囲に含まれる。
【００６６】
例えば、上記実施の形態では、レーザビーム１２、１３を２分岐としたが、一つのレーザビームをＮ分岐し、Ｎ本のレーザビームを用いてＮ本のヒューズを同時切断できるようにした場合、最大Ｎ倍の処理速度が実現できる。
【００６７】
また、ビーム移動手段７、８としては、この実施の形態で示したミラーの回転によるガルバノミラーの他、ミラーを直線移動してビーム位置を調整する機構を採用することもできる。
【００６８】
また、副レーザビーム１３の光路において、２つのＸ、Ｙガルバノミラー７、８を設けているが、主レーザビーム１２及び副レーザビーム１３の少なくとも何れか一の光路に設ければよい。
【００６９】
また、ガルバノミラー７、８によるレーザビームの照射位置の調整をレーザ加工を始める前に予め行なっているが、多数並んだ被加工物のピッチが不規則な場合、Ｘ−Ｙステージ１０を移動させつつ、次の加工対象物に対して、ガルバノミラー７、８によるレーザビームの照射位置の調整を行なうことも可能である。
【００７０】
【発明の効果】
以上のように、本発明によれば、レーザ光源からのレーザビームを複数に分岐した後、集光して被加工物に照射する光学系を有している。従って、一つのレーザ光源で複数のレーザビームを形成することができるため、装置の簡略化を図りつつ、２以上の被加工物を同時に加工することが可能である。これにより、加工効率の向上を図ることができ、スポット品質も向上する。
【００７１】
また、分岐された複数のレーザビームのうち、少なくとも１つのレーザビームの照射位置をそれぞれ独立に調整し得るビーム移動手段を有している。従って、多数並ぶ被加工物のピッチの変化に対しても、同時加工する被加工物相互への照射位置を正確に合わせることができるため、最小スポット径を小さく保ったまま、複数の被加工物の配列方向と間隔に合わせて２以上の被加工物を同時に加工することが可能となる。
【００７２】
さらに、分岐された複数のレーザビームのそれぞれの光路に対して開閉が可能なシャッタを備えているため、２以上の被加工物を同時に選び、かつ対象となる２以上の被加工物のうちから加工すべき被加工物を選択して加工することが可能となる。
【００７３】
さらに、複数の被加工物を載置したステージを移動させることにより、ステージ上の全部の被加工物に対して、順次かつ迅速に加工を行うことができる。
【００７４】
また、複数のレーザビームの光路のうちすべてに又は一部に偏光切り換え素子を有している。従って、被加工物が切断し易い方向に合わせて、例えば細長いヒューズの場合ヒューズの長手方向に対して切断しやすい方向に合わせてレーザビームの偏光方向を切り換えることにより、レーザビームのエネルギを集中させることができるため、切断を効率よく行うことができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態であるレーザ加工装置の構成を示す模式図である。
【図２】本発明の第１の実施の形態であるレーザ加工装置によるレーザ加工方法に用いられる、半導体装置に形成されたヒューズの配置を示す平面図である。
【図３】本発明の第１の実施の形態であるレーザ加工装置によるレーザ加工方法を示す平面図である。
【図４】本発明の第１の実施の形態に対する比較例であるレーザ加工方法を示す平面図である。
【図５】本発明の第２の実施の形態であるレーザ加工装置の構成を示す模式図である。
【符号の説明】
１ ヒューズパターン
２ ウエハ（半導体基板）
３ 半導体チップ
４ 全反射ミラー
５ ビームスプリッタ（ハーフミラー）
６ シャッタ
７ Ｘガルバノミラー（ビーム移動手段）
８ Ｙガルバノミラー（ビーム移動手段）
９ 集光レンズ
１０ Ｘ−Ｙステージ
１１ 基板チャック
１２ 主レーザビーム
１３ 副レーザビーム
１４ レーザ光源
１５ 円偏光板
１６ 偏光子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser processing apparatus and a laser processing method, and more particularly to a laser processing apparatus and a laser processing method for performing a process of cutting a fuse formed on a semiconductor substrate with a laser beam.
[0002]
[Prior art]
A conventional laser processing apparatus collects a laser beam from a laser light source, irradiates the workpiece, and processes the workpiece. For a plurality of workpieces, a stage on which the plurality of workpieces are placed is moved with respect to one laser light source, and the plurality of workpieces are sequentially processed one by one.
[0003]
Taking relief of defective bits in a memory device as an example, a memory device is assumed to have a defect in a part of a memory cell in advance, and includes a fuse for switching the defective part to a normal spare memory cell. Yes. In the conventional technique, these fuses are selectively cut one by one using a laser processing apparatus.
[0004]
The same applies to a fuse for voltage adjustment used in a semiconductor device and a programming fuse in a logic device.
[0005]
By the way, the number of fuses in the device is rapidly increasing as the storage capacity is increased, for example, in a memory device. In the conventional method of cutting fuses one by one, the time for the cutting process is increased, and the device cost is reduced. This has led to an increase.
[0006]
Therefore, recently, in order to increase the processing capability, there are a processing apparatus using a plurality of laser light sources, a processing apparatus using one laser beam emitted from one laser light source and forming two laser beams. It is described in the following Patent Documents 1 to 4.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 4-67654
[Patent Document 2]
JP-A-11-104863
[Patent Document 3]
JP-A-11-245073
[Patent Document 4]
JP-A-2-137682
[0008]
[Problems to be solved by the invention]
However, since the processing apparatuses described in Patent Documents 1 to 3 have a plurality of laser light sources, the apparatus tends to increase in size and the cost of the apparatus also increases.
[0009]
In contrast, the processing apparatus described in Patent Document 4 uses only one laser light source, but when simultaneously irradiating two laser beams, it is difficult to adjust the distance between the laser beams, and a large number of objects are aligned. It is difficult to respond quickly to changes in the pitch of the workpiece.
[0010]
Also, as the number of fuses increases, the interval between fuses placed on the device is becoming narrower. At this time, the spot diameter needs to be increased to some extent in order to secure the irradiation range, and the minimum spot diameter Is difficult to keep small. In this case, since it is difficult to reduce the interval between the plurality of laser beams, the energy distribution of the laser beam is likely to deviate from the Gaussian distribution, resulting in a decrease in spot quality.
[0011]
The present invention was created in view of the problems of the above-described conventional example, and while keeping the apparatus simple, the minimum spot diameter is kept small even with respect to a change in the pitch of a large number of workpieces lined up, In addition, two or more workpieces can be selected simultaneously from a large number of workpieces without degrading the spot quality, and can be selectively machined, increasing the workpiece machining efficiency and reducing the machining time. A laser processing apparatus and a laser processing method are provided.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a first aspect of the present invention relates to a laser processing apparatus, and includes a laser light source, a stage on which a workpiece is placed and movable, and a plurality of laser beams emitted from the laser light source. An optical system for condensing and irradiating the workpiece after branching, a shutter that can be opened and closed with respect to each optical path of the plurality of branched laser beams, and the plurality of branched laser beams. Beam moving means capable of moving independently of each other and adjusting the irradiation position of the laser beam,
According to a second aspect of the present invention, there is provided the laser processing apparatus according to the first aspect, wherein the stage is arranged along the arrangement direction with respect to the workpieces on the stage which are arranged in a single direction at intervals. It is adjusted to move, the irradiation position of the plurality of laser beams is adjusted according to the arrangement direction and the interval of the workpieces,
The invention according to claim 3 relates to the laser processing apparatus according to claim 1 or 2, characterized in that a polarization switching element is provided in all or part of the optical path of the plurality of laser beams,
Invention of Claim 4 is related with the laser processing apparatus as described in any one of Claim 1 thru | or 3, The adjustment range of the irradiation interval of these laser beams is 50 micrometers or less,
The invention according to claim 5 relates to a laser processing method, wherein a laser light source, a stage on which a workpiece is placed and movable, and a laser beam from the laser light source are branched into a plurality of light beams and then condensed. An optical system for irradiating the workpiece, a shutter that can be opened and closed with respect to each optical path of the plurality of branched laser beams, and the plurality of branched laser beams are moved independently of each other, A laser processing apparatus having a beam moving means capable of adjusting an irradiation position of the laser beam, the irradiation position of the laser beam is adjusted by the beam moving means on the workpiece on the stage, and Select two or more workpieces simultaneously, selectively open and close the shutter, and move the stage to sequentially process the plurality of workpieces. The features,
A sixth aspect of the present invention relates to the laser processing method according to the fifth aspect of the present invention, wherein the stage is moved along the arrangement direction with respect to the workpieces on the stage which are arranged in a single direction at intervals. Adjusting to move, adjusting the irradiation position of the one or more laser beams according to the arrangement direction and interval of the workpieces,
A seventh aspect of the present invention relates to the laser processing method according to the fifth or sixth aspect, wherein a polarization switching element is provided in all or a part of an optical path of the plurality of laser beams, and the laser beam by the polarization switching element is provided. Characterized by adjusting the polarization direction according to the workpiece,
An eighth aspect of the invention relates to the laser processing method according to any one of the fifth to seventh aspects, wherein the workpiece is a fuse formed on a semiconductor device.
[0013]
Below, the effect | action show | played by the structure of the said invention is demonstrated.
[0014]
The laser processing apparatus of the present invention has an optical system that divides a laser beam from a laser light source into a plurality of beams and then collects and irradiates the workpiece. Accordingly, since a plurality of laser beams can be irradiated with one laser light source, it is possible to simultaneously process two or more workpieces while simplifying the apparatus. Thereby, improvement of processing efficiency can be aimed at.
[0015]
Moreover, it has a beam moving means capable of independently adjusting the irradiation position of at least one laser beam among the plurality of branched laser beams. Therefore, even with respect to a change in the pitch of a large number of workpieces arranged, by changing the irradiation position of at least one laser beam, the irradiation positions on the workpieces to be simultaneously processed can be accurately adjusted. It is possible to process two or more workpieces at the same time in accordance with the arrangement direction and intervals of the plurality of workpieces while keeping the minimum spot diameter small and reducing the spot quality.
[0016]
Furthermore, since a shutter that can be opened and closed with respect to each of the optical paths of the plurality of branched laser beams is provided, two or more workpieces can be selected at the same time and the target two or more workpieces can be selected. It becomes possible to select and process a workpiece to be processed.
[0017]
Furthermore, by moving the stage on which a plurality of workpieces are placed, all the workpieces on the stage can be processed sequentially and quickly.
[0018]
In addition, polarization switching elements are provided in all or part of the optical paths of the plurality of laser beams. Therefore, the energy of the laser beam is concentrated by switching the polarization direction of the laser beam in accordance with the direction in which the workpiece is easily cut, for example, in the case of an elongated fuse, in accordance with the direction in which the workpiece is easily cut with respect to the longitudinal direction of the fuse. Therefore, cutting can be performed efficiently.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0020]
(First embodiment)
(Configuration of laser processing equipment)
First, the structure of the laser processing apparatus which is the 1st Embodiment of this invention is demonstrated with reference to drawings.
[0021]
FIG. 1 is a schematic diagram showing the configuration of the laser processing apparatus according to the first embodiment.
[0022]
As shown in FIG. 1, the laser processing apparatus includes one laser light source 14, a beam splitter 5 composed of a half mirror that divides one laser beam into two, and one laser of the two laser beams. An X galvanometer mirror (beam moving means) 7 that scans another laser beam (sub laser beam) in the X direction independently of the beam (main laser beam) and the same laser beam. In addition, a Y galvanometer mirror (beam moving means) 8 that scans another laser beam in the Y direction, a shutter 6 that opens and closes the optical path of each laser beam, a condensing lens 9 that condenses the two laser beams, and a target For example, a semiconductor substrate 2 on which a plurality of fuses 1 are formed, which is a workpiece, is placed and moved in the X and Y directions.
[0023]
In FIG. 1, the other reference numeral 4 is a total reflection mirror installed in the optical path of the laser beam, 11 is a substrate chuck for fixing the semiconductor substrate 2 to the XY stage 10, and 12 and 13 are condenser lenses, respectively. 9 shows a main laser beam and a sub laser beam emitted from 9.
[0024]
In such a laser processing apparatus, the result of the electrical test is obtained while moving the XY stage 10 at a constant speed with respect to the array of fuses 1 which are arranged on the semiconductor substrate 2 and whose positions are known in advance. According to the data of the fuse 1 to be cut, a laser pulse is oscillated at a position where the position of the stage coincides with the position of the fuse 1 to be cut, and the fuse 1 is cut. Alternatively, the optical paths of the two branched laser beams can be blocked so that neither fuse 1 is processed.
[0025]
In this embodiment, the main laser beam 12 and the sub laser beam 13 are automatically adjusted in advance to the minimum interval of the fuse 1 array to be cut, and two fuses 1 can be cut simultaneously. However, at a location where data is given to cut only one of the adjacent fuses 1, the sub laser beam 13 can be blocked and only the main laser beam 12 can be irradiated by closing the shutter 6. As a result, two fuses can be selected at the same time and only one selected from them can be processed.
[0026]
The positional relationship between the main laser beam 12 and the sub laser beam 13 is adjusted as follows. That is, as shown in FIG. 1, the sub laser beam 13 is scanned by two X and Y galvanometer mirrors 7 and 8 which can scan one laser beam in the X and Y directions and adjust the irradiation position of the laser beam on the semiconductor substrate. Adjust the position. For example, if the arrangement of the fuses 1 is in the X direction as shown in FIG. 3, the irradiation position of the sub laser beam 13 is adjusted by the X galvanometer mirror 7 to change the main laser beam 12 and the sub laser beam 13 into the X direction. To adjust the minimum distance of the fuse 1 to be cut. Further, after the main laser beam 12 is aligned with the center portion of the fuse 1, the sub laser beam 13 is aligned with the center portion of the fuse 1 by the Y galvanometer mirror 8.
[0027]
In the laser processing apparatus of this embodiment, the laser irradiation operation including the laser beam irradiation position adjustment by adjusting the galvanometer mirrors 7 and 8, the oscillation on / off of the laser light source 14, and the shutter 6 opening / closing operation. , And movement of the XY stage 10 can be performed by computer control.
[0028]
The processing speed of the laser processing apparatus depends on the moving speed of the XY stage. By the way, when processing with a single laser beam as in the prior art, the moving speed is given by equation (1).

On the other hand, in this embodiment, since the two fuses 1 can be simultaneously processed using the two laser beams 12 and 13, the minimum irradiation time is twice that of the conventional method (FIG. 4) and the processing speed is also twice. It becomes. For example, when the laser oscillation frequency is 10 kHz and the minimum cut fuse interval is 5 μm, the conventional processing speed is 50 mm / second, but in this embodiment, it is 100 mm / second.
[0029]
The distance d between the fuses 1 in a current semiconductor device is generally 2 μm to 10 μm. The distance between the two laser beams 12 and 13 should be several times at most, and the maximum adjustable range is 50 μm. Is enough. In this embodiment, since only a minute optical axis adjustment is required, the angle change of the galvanometer mirrors 7 and 8 is also minute. Further, by making it possible to adjust the irradiation position of the laser beam, accurate alignment with the fuse 1 is possible, and the laser beam can be reliably irradiated to the fuse 1 even if the irradiation range is reduced to the maximum. is there. For this reason, a small diameter condensing lens 9 can be used, and the minimum spot diameter can be kept small in the condensing lens 9 using a telecentric optical system. A telecentric optical system refers to an optical system in which an outgoing beam emitted from a lens is vertical even if an incident beam has an angle.
[0030]
As described above, the laser processing apparatus according to the first embodiment of the present invention has the optical system that divides the laser beam from the laser light source into a plurality of beams and then collects and irradiates the fuse 1. . Accordingly, the two main and sub laser beams 12 and 13 can be irradiated with one laser light source. The apparatus can be simplified and two or more fuses 1 can be processed simultaneously. Thereby, improvement of processing efficiency can be aimed at.
[0031]
Further, beam moving means 7 and 8 capable of independently adjusting the irradiation position of at least one laser beam 12 or 13 out of the two branched main and sub laser beams 12 and 13 are provided. Therefore, even with respect to a change in the pitch of the fuses 1 arranged in a large number, by changing the irradiation position of at least one or more laser beams 12 and 13, it is possible to accurately match the irradiation positions of the fuses 1 to be simultaneously processed. For this reason, two or more fuses 1 can be simultaneously processed in accordance with the arrangement direction and interval of the plurality of fuses 1 without keeping the minimum spot diameter small and degrading the spot quality.
[0032]
Furthermore, since the shutter 6 that can be opened and closed with respect to the respective optical paths of the two branched main and sub laser beams is provided, two or more fuses 1 are selected at the same time, and two or more fuses 1 to be targeted are selected. It becomes possible to select and process the fuse 1 to be processed.
[0033]
Further, by moving the XY stage 10 on which a plurality of fuses 1 are mounted, all the fuses 1 on the XY stage 10 can be processed sequentially and rapidly.
[0034]
(Laser processing method)
Next, a laser processing method using the laser processing apparatus will be described.
[0035]
First, as shown in FIG. 2, a semiconductor substrate 2 in which a plurality of fuses (workpieces) 1 are arranged on the semiconductor chip 3 at equal intervals d in the X direction and the Y direction is a substrate on the XY stage 10. Fix to the chuck 11.
[0036]
Next, a laser beam is generated from the laser light source 14 in a state where the optical path of the laser beam is closed by the shutter 6. The angles of the X and Y galvanometer mirrors 7 and 8 are adjusted based on the position information of the fuse 1 on the semiconductor substrate 2. In this case, first, alignment is performed with respect to the first and second fuses 1 arranged in the X direction at intervals d.
[0037]
Next, the shutter 6 is opened, and the two branched laser beams are condensed by the condensing lens 9 to form the main laser beam 12 and the sub laser beam 13, and the first and second lasers arranged in the X direction, respectively. The second fuse 1 is irradiated. As a result, as shown in FIG. 3, the first and second fuses 1 arranged in the X direction are cut by instantaneous energy application by the laser pulse. Note that the process from alignment to fuse cutting can be performed in an intermittent movement, or by setting the fuse movement to an appropriate speed, the process from alignment to fuse cutting can be performed in a continuous movement. It can also be done.
[0038]
Next, after closing the shutter 6, the XY stage 10 is moved by a distance 2d in the X direction to align with the third and fourth fuses 1.
[0039]
Next, based on processing information set in advance, the shutter 6 capable of irradiating the fourth fuse 1 with the laser beam is opened, and the laser beam is condensed by the condenser lens 9 so that only the sub laser beam 13 is collected. And irradiating the fourth fuses 1 arranged in the X direction. After a predetermined time, the fourth fuse 1 is cut as shown in FIG.
[0040]
In this manner, the XY stage 10 is moved by a distance 2d in the X direction, and the fuses 1 arranged in the X direction are sequentially laser processed as shown in FIG.
[0041]
Next, the fuses 1 arranged in the Y direction are processed.
[0042]
First, a laser beam is generated from the laser light source 14 in a state where the optical path of the laser beam is closed by the shutter 6. The angles of the X and Y galvanometer mirrors 7 and 8 are adjusted based on the position information of the fuse 1 on the semiconductor substrate 2. In this case, alignment is performed with respect to the first and second fuses 1 arranged in the Y direction at intervals d.
[0043]
Next, the shutter 6 is opened, and the two branched laser beams are condensed by the condenser lens 9 to form the main laser beam 12 and the sub laser beam 13, which are respectively arranged in the Y direction. The second fuse 1 is irradiated. After a predetermined time, the first and second fuses 1 arranged in the Y direction are blown.
[0044]
Thereafter, in the same manner as described above, the XY stage 10 is moved by a distance 2d that is twice the distance d between adjacent fuses in the Y direction, and laser processing is sequentially performed on the fuses 1 arranged in the Y direction.
[0045]
As described above, according to the laser processing method of the first embodiment of the present invention, after the laser beam from the laser light source 14 is branched into a plurality of beams, the branched laser beam is condensed and the main laser beam 12 and A sub laser beam 13 is formed and irradiated to each fuse 1. Therefore, simultaneous processing of a plurality of fuses 1 is possible. Thereby, improvement of processing efficiency can be aimed at.
[0046]
Further, the irradiation position of the sub laser beam 13 of the two branched main and sub laser beams 12 and 13 is adjusted, and the main and sub laser beams 12 and 13 are respectively aligned with the positions of the adjacent fuses 1. ing. Therefore, even when the pitches of the fuses 1 arranged in a large number are changed, the irradiation positions on the fuses 1 to be simultaneously processed can be accurately adjusted. For this reason, it is possible to process the two fuses 1 simultaneously while keeping the minimum spot diameter small.
[0047]
Further, since the shutter 6 that can be opened and closed with respect to the respective optical paths of the two branched laser beams is provided, two adjacent fuses 1 are simultaneously selected and processed from the two target fuses. It is possible to select a desired fuse and process it, or not to process it together.
[0048]
Further, the stage 10 on which the semiconductor substrate 2 on which the plurality of fuses 1 are formed is moved by a predetermined interval dx or dy, so that all the fuses 1 on the semiconductor substrate 2 are sequentially and quickly performed. be able to.
[0049]
(Second Embodiment)
(Laser processing equipment)
FIG. 5 is a schematic diagram showing the configuration of the laser processing apparatus according to the second embodiment.
[0050]
As shown in FIG. 5, the laser processing apparatus is obtained by adding a polarization switching element 16 to the laser processing apparatus of the first embodiment. After the light from the laser light source 14 is once changed into circularly polarized light by the circularly polarizing plate 15, each laser beam can be polarized in any direction by the polarization switching element 16 inserted in each of the optical paths of the two branched laser beams. It has become.
[0051]
By making the direction of the fuse 1 parallel to the polarization direction of the laser beam, it may be possible to more reliably cut the fuse 1 that is concentrated by concentrating the energy of the laser beam. In such a case, the laser processing apparatus according to the second embodiment is useful.
[0052]
Depending on the semiconductor device, when the polarization direction is perpendicular or oblique to the fuse 1, good cutting may be possible. When the longitudinal direction of the fuse 1 is arranged in both X and Y directions, the polarization of one laser beam is aligned in the X direction, the other is aligned in the Y direction, and each laser beam is selected in accordance with the direction of the fuse 1 If used, the fuse 1 in both directions can be efficiently cut.
[0053]
As described above, according to the laser processing apparatus of the second embodiment of the present invention, since the polarization switching element 16 is provided, the irradiation is performed by aligning the polarization direction of each laser beam in the direction in which the fuse 1 is easily cut. As a result, it is possible to efficiently cut the fuse 1 in each direction by concentrating the energy of the laser beam.
[0054]
(Laser processing method)
Next, a laser processing method using the laser processing apparatus according to the second embodiment of the present invention will be described with reference to FIG.
[0055]
First, the semiconductor substrate 2 is fixed to the substrate chuck 11 on the XY stage 10 shown in FIG.
[0056]
First, processing is performed on the fuses 1 arranged at intervals d in the X direction. In this case, a laser beam is generated from the laser light source 14 with the optical path of the laser beam closed by the shutter 6. The angles of the X and Y galvanometer mirrors 7 and 8 are adjusted based on the position information of the fuse 1 on the semiconductor substrate 2. In this case, first, alignment is performed with respect to the first and second fuses 1 arranged in the X direction at intervals d.
[0057]
Next, the shutter 6 is opened. In this case, the laser beam is circularly polarized by the circular polarization element 15, then reflected by the total reflection mirror 4 and incident on the beam splitter 5. One of the two branched laser beams sequentially passes through the polarization switching element 16 and the condenser lens 9 to form the main laser beam 12. The other is transmitted through the polarization switching element 16, reflected by the total reflection mirror 4, and sequentially incident on the X and Y galvanometer mirrors 7 and 8. The irradiation positions of the laser beams transmitted through the X and Y galvanometer mirrors 7 and 8 are adjusted and transmitted through the condenser lens 9 to form a secondary laser beam 13. For example, in the case of an elongated fuse 1, the polarization direction of the main and sub laser beams 12, 13 is adjusted by the polarization switching element 16 in a direction that can be easily cut with respect to the longitudinal direction of the fuse 1. In this case, since all the fuses 1 to be processed are arranged in the X direction, the same polarization direction is set for the main and sub laser beams 12 and 13.
[0058]
The main and sub laser beams 12 and 13 thus formed are irradiated to the first and second fuses 1 arranged in the X direction. After a predetermined time, the first and second fuses 1 arranged in the X direction are blown.
[0059]
Next, after the shutter 6 is closed, the XY stage 10 is moved in the X direction by a distance 2d that is twice the distance d adjacent to the fuse, and is aligned with the third and fourth fuses 1. The laser processing is performed in the same manner as in the first embodiment.
[0060]
In this way, the XY stage 10 is moved by the distance 2d in the X direction, and the adjacent fuses 1 are sequentially selected for the fuses 1 arranged in the X direction two by two at the same time. To process.
[0061]
Next, processing is performed on the fuses 1 arranged at intervals d in the Y direction. First, in the same manner as when processing is performed on the fuses 1 arranged in the X direction, the first and second fuses 1 arranged in the Y direction at intervals d are aligned.
[0062]
Next, in the same manner as when processing is performed on the fuses 1 arranged in the X direction, the polarization of the main and sub laser beams 12 and 13 is adjusted by the polarization switching element 16 in the direction in which the fuse 1 is easily cut. Set the direction. In this case, since all the fuses 1 to be processed are arranged in the Y direction, the main and sub laser beams 12 in a direction orthogonal to the case where the fuses 1 arranged in the X direction are processed, for example, 13 polarization directions are set. In addition, since all the fuses 1 to be processed are arranged in the Y direction, the main and sub laser beams 12 and 13 are set in the same polarization direction. The main and sub laser beams 12 and 13 thus formed are irradiated to the first and second fuses 1 arranged in the Y direction. After a predetermined time, the first and second fuses 1 arranged in the Y direction are blown.
[0063]
Thereafter, in the same manner as described above, the XY stage 10 is moved by a distance 2d in the Y direction, and the adjacent fuses 1 are sequentially selected two by two at the same time with respect to the fuses 1 arranged in the Y direction. To perform laser processing selectively.
[0064]
As described above, according to the laser processing method of the second embodiment, the polarization directions of the laser beams 12 and 13 are switched in accordance with the direction in which the fuse 1 can be easily cut. For this reason, since the energy of the laser beams 12 and 13 can be concentrated, the fuse 1 can be efficiently cut.
[0065]
Although the present invention has been described in detail with the embodiments, the scope of the present invention is not limited to the examples specifically shown in the above embodiments, and the above embodiments within the scope of the present invention are not deviated. Variations in form are within the scope of this invention.
[0066]
For example, in the above embodiment, the laser beams 12 and 13 are divided into two branches, but when one laser beam is divided into N branches and N laser beams are used to simultaneously cut N fuses, A processing speed of up to N times can be realized.
[0067]
Further, as the beam moving means 7 and 8, a mechanism for adjusting the beam position by linearly moving the mirror can be adopted in addition to the galvanometer mirror by the rotation of the mirror shown in this embodiment.
[0068]
In addition, although the two X and Y galvanometer mirrors 7 and 8 are provided in the optical path of the sub laser beam 13, they may be provided in at least one of the main laser beam 12 and the sub laser beam 13.
[0069]
Further, the adjustment of the irradiation position of the laser beam by the galvanometer mirrors 7 and 8 is performed in advance before the laser processing is started, but when the pitch of the workpieces arranged in a large number is irregular, the XY stage 10 is moved. However, it is also possible to adjust the irradiation position of the laser beam by the galvanometer mirrors 7 and 8 for the next workpiece.
[0070]
【The invention's effect】
As described above, according to the present invention, the laser beam from the laser light source is branched into a plurality of light beams, and then condensed to irradiate the workpiece. Accordingly, since a plurality of laser beams can be formed with one laser light source, it is possible to simultaneously process two or more workpieces while simplifying the apparatus. Thereby, improvement of processing efficiency can be aimed at and spot quality also improves.
[0071]
Moreover, it has a beam moving means capable of independently adjusting the irradiation position of at least one laser beam among the plurality of branched laser beams. Therefore, it is possible to accurately match the irradiation position of the workpieces to be processed simultaneously even when the pitch of the workpieces lined up is large, so that multiple workpieces can be maintained while keeping the minimum spot diameter small. It is possible to simultaneously process two or more workpieces in accordance with the arrangement direction and the interval.
[0072]
Furthermore, since a shutter that can be opened and closed with respect to each of the optical paths of the plurality of branched laser beams is provided, two or more workpieces can be selected at the same time and the target two or more workpieces can be selected. It becomes possible to select and process a workpiece to be processed.
[0073]
Furthermore, by moving the stage on which a plurality of workpieces are placed, all the workpieces on the stage can be processed sequentially and quickly.
[0074]
In addition, polarization switching elements are provided in all or part of the optical paths of the plurality of laser beams. Therefore, the energy of the laser beam is concentrated by switching the polarization direction of the laser beam in accordance with the direction in which the workpiece is easily cut, for example, in the case of an elongated fuse, in accordance with the direction in which the workpiece is easily cut with respect to the longitudinal direction of the fuse. Therefore, cutting can be performed efficiently.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration of a laser processing apparatus according to a first embodiment of the present invention.
FIG. 2 is a plan view showing the arrangement of fuses formed in the semiconductor device used in the laser processing method by the laser processing apparatus according to the first embodiment of the present invention.
FIG. 3 is a plan view showing a laser processing method by the laser processing apparatus according to the first embodiment of the present invention.
FIG. 4 is a plan view showing a laser processing method which is a comparative example with respect to the first embodiment of the present invention.
FIG. 5 is a schematic diagram showing a configuration of a laser processing apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
1 Fuse pattern
2 Wafer (semiconductor substrate)
3 Semiconductor chip
4 Total reflection mirrors
5 Beam splitter (half mirror)
6 Shutter
7 X Galvano mirror (beam moving means)
8 Y Galvano mirror (beam moving means)
9 Condensing lens
10 XY stage
11 Substrate chuck
12 Main laser beam
13 Sub laser beam
14 Laser light source
15 circular polarizer
16 Polarizer

Claims (8)

A laser light source;
A stage on which a workpiece can be placed and moved;
An optical system for condensing and irradiating the workpiece after dividing the laser beam emitted from the laser light source into a plurality;
A shutter that can be opened and closed with respect to each optical path of the plurality of branched laser beams;
A laser processing apparatus comprising: a beam moving unit capable of moving the plurality of branched laser beams independently of each other and adjusting an irradiation position of the laser beam. The stage is adjusted so as to move along the arrangement direction with respect to the workpieces arranged at intervals in one direction, and the plurality of the workpieces are arranged in accordance with the arrangement direction and intervals of the workpieces. The laser processing apparatus according to claim 1, wherein an irradiation position of the laser beam is adjusted. 3. The laser processing apparatus according to claim 1, further comprising a polarization switching element in all or part of the optical paths of the plurality of laser beams. The laser processing apparatus according to claim 1, wherein an adjustment range of irradiation intervals of the plurality of laser beams is 50 μm or less. A laser light source, a stage on which a workpiece is placed and movable, an optical system that divides a laser beam emitted from the laser light source into a plurality of beams, and then collects and irradiates the workpiece, and the branch A shutter that can be opened and closed with respect to the respective optical paths of the plurality of laser beams, and beam moving means that can move the plurality of branched laser beams independently of each other and adjust the irradiation position of the laser beams. Using a laser processing apparatus having
A plurality of workpieces are placed on the stage, and the irradiation position of the laser beam is adjusted by the beam moving means according to the positions of the plurality of workpieces. A laser processing method characterized in that two or more are simultaneously selected, the shutter is opened and closed to selectively process, and the stage is moved to sequentially process the plurality of workpieces. The stage is adjusted to move along the arrangement direction with respect to the plurality of workpieces arranged at intervals in one direction, and the laser beam is adjusted in accordance with the arrangement direction and intervals of the workpieces. 6. The laser processing method according to claim 5, wherein the irradiation position is adjusted. 6. A polarization switching element is provided in all or a part of the optical paths of the plurality of laser beams, and a polarization direction of the laser beam by the polarization switching element is adjusted in accordance with the workpiece. Or the laser processing method of 6. The laser processing method according to claim 5, wherein the workpiece is a fuse formed on a semiconductor device.

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