JP6779486B2 - Substrate processing method and substrate processing equipment - Google Patents

Substrate processing method and substrate processing equipment Download PDF

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JP6779486B2
JP6779486B2 JP2016215244A JP2016215244A JP6779486B2 JP 6779486 B2 JP6779486 B2 JP 6779486B2 JP 2016215244 A JP2016215244 A JP 2016215244A JP 2016215244 A JP2016215244 A JP 2016215244A JP 6779486 B2 JP6779486 B2 JP 6779486B2
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順一 池野
順一 池野
山田 洋平
洋平 山田
鈴木 秀樹
秀樹 鈴木
利香 松尾
利香 松尾
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Shin Etsu Polymer Co Ltd
Saitama University NUC
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Saitama University NUC
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本発明は、加工対象結晶基板の表面から内部にレーザ光を集光することで、加工対象結晶基板内部に加工層を形成する基板加工方法および基板加工装置に関する。 The present invention relates to a substrate processing method and a substrate processing apparatus for forming a processing layer inside a processing target crystal substrate by condensing laser light from the surface of the processing target crystal substrate to the inside.

従来、単結晶のシリコン(Si)ウエハに代表される半導体ウエハを製造する場合には、石英るつぼ内に溶融されたシリコン融液から凝固した円柱形のインゴットを適切な長さのブロックに切断して、その周縁部を目標の直径になるよう研削し、その後、ブロック化されたインゴットをワイヤソーによりウエハ形にスライスして半導体ウエハを製造するようにしている(例えば特許文献1参照)。 Conventionally, when manufacturing a semiconductor wafer typified by a single crystal silicon (Si) wafer, a cylindrical ingot solidified from a silicon melt melted in a quartz crucible is cut into blocks of an appropriate length. Then, the peripheral portion thereof is ground to a target diameter, and then the blocked ingot is sliced into a wafer shape by a wire saw to manufacture a semiconductor wafer (see, for example, Patent Document 1).

このようにして製造された半導体ウエハは、前工程で回路パターンの形成等、各種の処理が順次施されて後工程に供され、この後工程で裏面がバックグラインド処理されて薄片化が図られることにより、厚さが約750μmから100μm以下、例えば75μmや50μm程度に調整される。 The semiconductor wafer manufactured in this way is subjected to various processes such as forming a circuit pattern in the pre-process and is subjected to the post-process, and the back surface is back-grinded in the post-process to be thinned. As a result, the thickness is adjusted from about 750 μm to 100 μm or less, for example, about 75 μm or 50 μm.

従来における半導体ウエハは、以上のように製造され、インゴットがワイヤソーにより切断され、しかも、切断の際にワイヤソーの太さ以上の切り代が必要となるので、厚さ0.1mm以下の薄い半導体ウエハを製造することが非常に困難であり、製品率も向上しない。 Conventional semiconductor wafers are manufactured as described above, and the ingot is cut by a wire saw, and a cutting allowance larger than the thickness of the wire saw is required for cutting. Therefore, a thin semiconductor wafer having a thickness of 0.1 mm or less is required. It is very difficult to manufacture and the product rate does not improve.

特開2005−297156号公報Japanese Unexamined Patent Publication No. 2005-297156

ところで、単結晶基板の寸法が使用予定の寸法よりも大きい場合、この単結晶基板を良好な形状で小さい寸法にして再利用することができれば効率的である。また、このことは、単結晶基板に限らず、他の種類の基板であっても該当することが多々ある。 By the way, when the size of the single crystal substrate is larger than the size to be used, it is efficient if the single crystal substrate can be reused in a good shape and small size. Further, this is often applicable not only to a single crystal substrate but also to other types of substrates.

一方、レーザ光をウエハ内部に集光してウエハ内部に改質領域を形成してウエハをダイシングする加工方法が提案されている。一般的に、この加工方法では内部集光したレーザ光による熱吸収により改質層がレーザ光照射側に延びることを利用している。この方法はダイシングする際の加工時間短縮には効果的であるが、改質層の亀裂の進展により断面形状の悪化や、加工対象結晶基板の予期しない結晶方位に沿って亀裂が進展してしまうことが懸念される。そのためウエハをくり抜くときに、その断面形状の悪化や、加工精度の低下及びウエハ表面の欠けなどの不具合が生じることが懸念される。 On the other hand, a processing method has been proposed in which laser light is focused inside the wafer to form a modified region inside the wafer and the wafer is diced. In general, this processing method utilizes the fact that the modified layer extends to the laser beam irradiation side due to heat absorption by the internally focused laser beam. This method is effective in shortening the processing time during dicing, but the growth of cracks in the modified layer causes deterioration of the cross-sectional shape and cracks that grow along the unexpected crystal orientation of the crystal substrate to be processed. Is a concern. Therefore, when the wafer is hollowed out, there is a concern that defects such as deterioration of the cross-sectional shape, deterioration of processing accuracy, and chipping of the wafer surface may occur.

本発明は、上記課題に鑑み、加工対象結晶基板を、欠けのないくり抜き結晶基板を得るための加工層含有基板に加工する基板加工方法および基板加工装置を提供することを課題とする。 In view of the above problems, it is an object of the present invention to provide a substrate processing method and a substrate processing apparatus for processing a crystal substrate to be processed into a processed layer-containing substrate for obtaining a hollow crystal substrate without chips.

上記課題を解決するための本発明の一態様によれば、レーザ光を集光するとともに収差補正が調整可能なレーザ集光手段を、加工対象結晶基板の被照射面上に非接触に配置する第1工程と、前記レーザ集光手段により加工対象結晶基板内部にレーザ光を集光しつつ、レーザ光の集光位置を前記加工対象結晶基板のくり抜き対象部の周囲方向および厚み方向に変化させ、破断強度が低下した加工層を前記くり抜き対象部の外周側に形成することで加工層含有基板とする第2工程と、を備え、前記第2工程では、加工対象結晶基板内部および少なくとも一方の加工対象結晶基板面近傍で、レーザ光の集光位置において生じる加工痕が、前記加工対象結晶基板の結晶方位に沿って伸張しかつ前記加工対象結晶基板の異なる結晶方位に沿って伸張しないように前記レーザ集光手段の収差補正を調整する基板加工方法が提供される。 According to one aspect of the present invention for solving the above problems, a laser condensing means capable of condensing laser light and adjusting aberration correction is arranged non-contactly on the irradiated surface of the crystal substrate to be processed. In the first step, while condensing the laser light inside the crystal substrate to be processed by the laser condensing means, the condensing position of the laser light is changed in the peripheral direction and the thickness direction of the hollowed out target portion of the crystal substrate to be processed. A second step of forming a processed layer containing a processed layer by forming a processed layer having a reduced breaking strength on the outer peripheral side of the hollowed-out target portion is provided. In the second step, the inside of the crystal substrate to be processed and at least one of them are provided. To prevent the processing marks generated at the light condensing position of the laser beam near the surface of the crystal substrate to be processed to extend along the crystal orientation of the crystal substrate to be processed and not to extend along different crystal orientations of the crystal substrate to be processed. A substrate processing method for adjusting the aberration correction of the laser condensing means is provided.

また、本発明の別の一態様によれば、載置された加工対象結晶基板を保持して回転する回転ステージと、前記回転ステージ上に保持された前記加工対象結晶基板に向けてレーザ光を集光するとともにレーザ光の収差補正が調整可能なレーザ集光手段と、前記回転ステージと前記レーザ集光手段との距離を変える照射軸方向距離変更手段と、前記距離に応じて前記収差補正の調整を制御する収差補正制御手段と、を備え、前記収差補正制御手段は、加工対象結晶基板内部および少なくとも一方の加工対象結晶基板面近傍で、レーザ光集光位置において生じる加工痕が前記加工対象結晶基板の結晶方位に沿って伸張しかつ前記加工対象結晶基板の異なる結晶方位に沿って伸張しないように制御する基板加工装置が提供される。 Further, according to another aspect of the present invention, the laser beam is directed toward the rotating stage that holds and rotates the mounted crystal substrate to be processed and the crystal substrate to be processed that is held on the rotating stage. Laser condensing means that can adjust the aberration correction of the laser light while condensing, irradiation axis direction distance changing means that changes the distance between the rotating stage and the laser condensing means, and the aberration correction according to the distance. The aberration correction control means includes an aberration correction control means for controlling adjustment, and the aberration correction control means has a processing mark generated at a laser light condensing position inside the processing target crystal substrate and near at least one processing target crystal substrate surface. Provided is a substrate processing apparatus for controlling the elongation along the crystal orientation of the crystal substrate and not extending along the different crystal orientations of the crystal substrate to be processed.

本発明によれば、加工対象結晶基板を、欠けのないくり抜き結晶基板を得るための加工層含有基板に加工する基板加工方法および基板加工装置を提供することができる基板加工方法および基板加工装置を提供することができる。 According to the present invention, there is a substrate processing method and a substrate processing apparatus capable of providing a substrate processing method and a substrate processing apparatus for processing a crystal substrate to be processed into a processed layer-containing substrate for obtaining a hollow crystal substrate without chips. Can be provided.

第1実施形態に係る基板加工装置を説明する模式的な側面図である。It is a schematic side view explaining the substrate processing apparatus which concerns on 1st Embodiment. (a)から(c)は、それぞれ、第1実施形態に係る基板加工方法により加工層含有基板を製造するプロセスを説明する模式的な側面図である。(A) to (c) are schematic side views for explaining the process of manufacturing a processed layer-containing substrate by the substrate processing method according to the first embodiment, respectively. (a)および(b)は、それぞれ、第1実施形態に係る基板加工方法により加工層が形成されていくことを示す模式的な側面断面図である。(A) and (b) are schematic side sectional views showing that a processed layer is formed by the substrate processing method which concerns on 1st Embodiment, respectively. 第1実施形態で、加工層含有基板からくり抜き対象部をくり抜くことを説明する模式的な斜視図である。It is a schematic perspective view explaining the hollowing-out target part from the processed layer containing substrate in 1st Embodiment. 第1実施形態に係る基板加工装置で、収差補正環としての機能を説明するための模式的な側面図である。It is a schematic side view for demonstrating the function as an aberration correction ring in the substrate processing apparatus which concerns on 1st Embodiment. 第1実施形態に係る基板加工方法で形成された加工層に加工痕が配列されていることを説明する模式的な説明図である。It is a schematic explanatory drawing explaining that the processing mark is arranged in the processing layer formed by the substrate processing method which concerns on 1st Embodiment. 実験例1で、第1実施形態の一例(実施例1)で得られた加工層含有基板の側面断面を示す写真図である。FIG. 5 is a photographic view showing a side cross section of a processed layer-containing substrate obtained in an example of the first embodiment (Example 1) in Experimental Example 1. (a)および(b)は、それぞれ、実験例2の測定結果を示すグラフ図および数値の説明図である。(A) and (b) are a graph showing the measurement result of Experimental Example 2 and an explanatory diagram of numerical values, respectively. 実験例2の測定結果を示すグラフ図である。It is a graph which shows the measurement result of Experimental Example 2. 実験例3で、第1実施形態の一例(実施例2)を行うときのレーザ光の焦点位置を説明する模式的な側面図である。FIG. 5 is a schematic side view for explaining the focal position of the laser beam when one example (Example 2) of the first embodiment is performed in Experimental Example 3. 実験例3で、レーザ光の焦点位置を上方に移動させる際に仮に収差補正を行わなかったときに集光不十分となることを説明する模式的な側面図である。FIG. 3 is a schematic side view for explaining that in Experimental Example 3, when the focal position of the laser beam is moved upward, the light collection is insufficient if the aberration correction is not performed. 実験例3で、レーザ光の焦点位置を上方に移動させる際に収差補正を行うことで、焦点位置で十分に集光させつつ移動させることを説明する模式的な側面図である。FIG. 3 is a schematic side view for explaining that in Experimental Example 3, when the focal position of the laser beam is moved upward, aberration correction is performed so that the laser beam is moved while being sufficiently focused at the focal position. (a)および(b)は、それぞれ、実験例3で、補正環なして照射したときの焦点を説明する模式的断面図である。(A) and (b) are schematic cross-sectional views for explaining the focal point when irradiation is performed without a correction ring in Experimental Example 3, respectively. 実験例3で、補正環ありで照射したときの焦点を説明する模式的断面図である。FIG. 3 is a schematic cross-sectional view illustrating the focal point when irradiated with a correction ring in Experimental Example 3. 実験例4で、第1実施形態の一例(実施例3)によって得られた加工層含有基板からくり抜き対象部をくり抜いたことを説明する写真図である。FIG. 5 is a photographic diagram illustrating that the hollowed-out target portion was hollowed out from the processed layer-containing substrate obtained in the first embodiment (Example 3) in Experimental Example 4. 実験例3で、比較例1によって得られた加工層含有基板の部分側面断面を示す写真図である。FIG. 5 is a photographic view showing a partial side cross section of the processed layer-containing substrate obtained in Comparative Example 1 in Experimental Example 3. 第2実施形態に係る基板加工方法により製造した加工層含有基板を示す模式的な側面断面図である。It is a schematic side sectional view which shows the processed layer containing substrate manufactured by the substrate processing method which concerns on 2nd Embodiment.

以下、添付図面を参照して、本発明の実施の形態について説明する。以下の説明では、すでに説明したものと同一または類似の構成要素には同一または類似の符号を付し、その詳細な説明を適宜省略している。また、以下に示す実施の形態は、この発明の技術的思想を具体化するための例示であって、この発明の実施の形態は、構成部品の材質、形状、構造、配置等を下記のものに特定するものではない。この発明の実施の形態は、要旨を逸脱しない範囲内で種々変更して実施できる。 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, components that are the same as or similar to those already described are designated by the same or similar reference numerals, and detailed description thereof will be omitted as appropriate. Further, the embodiments shown below are examples for embodying the technical idea of the present invention, and the embodiments of the present invention describe the materials, shapes, structures, arrangements, etc. of the components as follows. It is not specific to. Embodiments of the present invention can be variously modified and implemented without departing from the gist.

[第1実施形態]
まず、第1実施形態を説明する。図1は、本実施形態に係る基板加工装置を説明する模式的な側面図である。図2で(a)から(c)は、それぞれ、本実施形態に係る基板加工方法により加工層含有基板を製造するプロセスを説明する模式的な側面図である。図3で(a)および(b)は、それぞれ、本実施形態に係る基板加工方法により加工層が形成されていくことを示す模式的な側面断面図である。図4は、本実施形態で、加工層含有基板からくり抜き対象部をくり抜くことを説明する模式的な斜視図である。図5は、本実施形態に係る基板加工装置で、収差補正環としての機能を説明するための模式的な側面図である。図6は、本実施形態に係る基板加工方法で形成された加工層に加工痕が配列されていることを説明する模式的な説明図である。
[First Embodiment]
First, the first embodiment will be described. FIG. 1 is a schematic side view for explaining the substrate processing apparatus according to the present embodiment. 2A to 2C are schematic side views for explaining a process of manufacturing a processed layer-containing substrate by the substrate processing method according to the present embodiment, respectively. 3A and 3B are schematic side sectional views showing that a processed layer is formed by the substrate processing method according to the present embodiment, respectively. FIG. 4 is a schematic perspective view illustrating that the hollowed-out target portion is hollowed out from the processed layer-containing substrate in the present embodiment. FIG. 5 is a schematic side view for explaining the function of the substrate processing apparatus according to the present embodiment as an aberration correction ring. FIG. 6 is a schematic explanatory view for explaining that processing marks are arranged in the processing layer formed by the substrate processing method according to the present embodiment.

(基板加工装置)
図1、図2に示すように、本実施形態に係る基板加工装置10は、載置された加工対象結晶基板20aを保持して回転する回転ステージ11と、回転ステージ11のステージ面Su上に保持された加工対象結晶基板20aに向けてレーザ光Bを集光するレーザ集光手段12(例えば集光器)と、を備える。レーザ集光手段12は、レーザ発振装置Jから出射したレーザ光が入射するようになっている。また、基板加工装置10は、回転ステージ11とレーザ集光手段12との距離Lを変える照射軸方向距離変更手段(図示せず)と、この距離Lに応じてレーザ集光手段12の収差補正の調整状態を制御する収差補正制御手段13と、を備える。更に基板加工装置10は、回転ステージ11の回転中心軸Csとレーザ集光手段12の照射中心軸Cbとの距離rを変える半径方向距離変更手段(図示せず)を備える。
(Substrate processing equipment)
As shown in FIGS. 1 and 2, the substrate processing apparatus 10 according to the present embodiment is placed on a rotating stage 11 that holds and rotates the mounted crystal substrate 20a to be processed, and on the stage surface Su of the rotating stage 11. A laser condensing means 12 (for example, a concentrator) that condenses the laser beam B toward the held crystal substrate 20a to be processed is provided. The laser condensing means 12 is adapted to receive the laser light emitted from the laser oscillator J. Further, the substrate processing apparatus 10 includes an irradiation axis direction distance changing means (not shown) that changes the distance L between the rotating stage 11 and the laser condensing means 12, and aberration correction of the laser condensing means 12 according to the distance L. The aberration correction control means 13 for controlling the adjustment state of the above is provided. Further, the substrate processing apparatus 10 includes radial distance changing means (not shown) for changing the distance r between the rotation center axis Cs of the rotation stage 11 and the irradiation center axis Cb of the laser condensing means 12.

照射軸方向距離変更手段としては、レーザ集光手段12を回転ステージ11に対して遠近方向に移動させる機構であってもよいし、回転ステージ11をレーザ集光手段12に対して遠近方向に移動させる機構(例えば、XステージあるいはXYステージ)であってもよい。 The irradiation axis direction distance changing means may be a mechanism for moving the laser condensing means 12 in the perspective direction with respect to the rotating stage 11, or the rotating stage 11 may be moved in the perspective direction with respect to the laser condensing means 12. It may be a mechanism for causing (for example, an X stage or an XY stage).

半径方向距離変更手段としては、レーザ集光手段12をステージ面Suに平行な一方向(例えば図1、図2のX方向)に移動させる移動機構であってもよいし、回転ステージ11をステージ面Suに平行な一方向(例えば図1、図2のX方向)に移動させる移動機構であってもよい。 The radial distance changing means may be a moving mechanism for moving the laser condensing means 12 in one direction parallel to the stage surface Su (for example, the X direction in FIGS. 1 and 2), or the rotating stage 11 may be staged. It may be a moving mechanism that moves in one direction parallel to the surface Su (for example, the X direction in FIGS. 1 and 2).

収差補正制御手段13は、距離Lに応じてレーザ集光手段12の収差補正(詳細は後述)を調整する制御信号を送信している。この収差補正制御手段13は、加工対象結晶基板20a内部および少なくとも一方の加工対象結晶基板面近傍(表面近傍(上面近傍)または裏面近傍(下面近傍))で、レーザ光Bの集光位置Bfに生じる加工痕22c(図6参照)が加工対象結晶基板20aの結晶方位(例えば[100]方位)に沿って伸張(後述)しかつ加工対象結晶基板20aの異なる結晶方位(例えば[111]方位や[110]方位)に沿って伸張しないようにレーザ集光手段12の収差補正を調整するようになっている。 The aberration correction control means 13 transmits a control signal for adjusting the aberration correction (details will be described later) of the laser condensing means 12 according to the distance L. The aberration correction control means 13 is located inside the crystal substrate 20a to be processed and near the surface of at least one crystal substrate to be processed (near the front surface (near the upper surface) or near the back surface (near the lower surface)) at the condensing position Bf of the laser beam B. The generated processing marks 22c (see FIG. 6) extend (described later) along the crystal orientation (for example, [100] orientation) of the crystal substrate 20a to be processed, and the different crystal orientations (for example, [111] orientation) of the crystal substrate 20a to be processed The aberration correction of the laser condensing means 12 is adjusted so as not to extend along the [110] orientation).

ここで、加工対象結晶基板の結晶方位と異なる結晶方位に沿って加工痕が伸張するとは、例えば結晶方位[100]の単結晶シリコンウエハを基板材料とした場合、結晶方位[100]に沿って加工痕を基板厚さ方向に形成する必要があるが、単結晶シリコンではより結合力の弱い[111]および[110]方位(異なる結晶方位)に劈開が起こりやすく、加工痕がこれらの結晶方位に沿って進展することをいう。このことによって、くり抜き断面が不均一になったり、欠けや割れなどが生じたりする。 Here, the fact that the processing marks extend along a crystal orientation different from the crystal orientation of the crystal substrate to be processed means that, for example, when a single crystal silicon wafer having a crystal orientation [100] is used as the substrate material, the processing marks extend along the crystal orientation [100]. It is necessary to form processing marks in the thickness direction of the substrate, but single crystal silicon is more likely to open in the [111] and [110] orientations (different crystal orientations), which have weaker bonding forces, and the processing marks are in these crystal orientations. It means to progress along with. As a result, the hollowed-out cross section becomes uneven, and chips and cracks occur.

本実施形態では、収差補正制御手段13がこのような収差補正の制御を行う加工対象結晶基板面近傍をレーザ光Bの被照射面20u(表面)近傍、あるいは、被照射面20uとは反対側の面、すなわち回転ステージ側の面(裏面20v)近傍とされている。基板加工装置10では、収差補正制御手段13が行うこのような制御を表面近傍とするか裏面近傍とするかを切り替えスイッチなどにより切替可能な装置構成にされていてもよい。 In the present embodiment, the vicinity of the surface of the crystal substrate to be processed by the aberration correction control means 13 for controlling such aberration correction is near the irradiated surface 20u (surface) of the laser beam B, or on the side opposite to the irradiated surface 20u. That is, it is in the vicinity of the surface on the rotating stage side (back surface 20v). The substrate processing apparatus 10 may have an apparatus configuration in which such control performed by the aberration correction control means 13 can be switched between the vicinity of the front surface and the vicinity of the back surface by a changeover switch or the like.

レーザ集光手段12は、本実施形態では、図5、図6に示すように、集光レンズ15を備えており、収差補正の調整機能、すなわち収差補正環としての機能を有している。具体的には、集光レンズ15は、空気中で集光した際に、集光レンズ15の外周部Eに到達したレーザ光が集光レンズ15の中央部Mに到達したレーザ光よりも集光レンズ側で集光するように補正する構成になっている。つまり、集光した際、集光レンズ15の外周部Eに到達したレーザ光の集光点EPが、集光レンズ15の中央部Mに到達したレーザ光の集光点MPに比べ、集光レンズ15に近い位置となるように補正する構成になっている。 In the present embodiment, the laser condensing means 12 includes a condensing lens 15 as shown in FIGS. 5 and 6, and has an aberration correction adjusting function, that is, a function as an aberration correction ring. Specifically, when the condenser lens 15 is focused in the air, the laser light that reaches the outer peripheral portion E of the condenser lens 15 is collected more than the laser light that reaches the central portion M of the condenser lens 15. The configuration is such that the light is focused on the optical lens side. That is, when condensing, the condensing point EP of the laser light that reaches the outer peripheral portion E of the condensing lens 15 is condensed as compared with the condensing point MP of the laser light that reaches the central portion M of the condensing lens 15. The configuration is such that the position is corrected so as to be close to the lens 15.

そして収差補正制御手段13は、加工対象結晶基板20aの表面近傍から加工痕の形成を開始する場合には、表面(被照射面20u)からの距離が大きい加工痕ほど加工痕長さが短くなるように制御し、加工対象結晶基板20aの裏面近傍から加工痕の形成を開始する場合には、裏面(裏面20v)からの距離が大きい加工痕ほど加工痕長さが短くなるように制御することが多い。 When the aberration correction control means 13 starts forming the processing mark from the vicinity of the surface of the crystal substrate 20a to be processed, the processing mark length becomes shorter as the distance from the surface (irradiated surface 20u) increases. When the formation of processing marks is started from the vicinity of the back surface of the crystal substrate 20a to be processed, the processing marks should be controlled so that the longer the distance from the back surface (back surface 20v) is, the shorter the processing marks are. There are many.

集光レンズ15は、空気中で集光する第1レンズ16と、この第1レンズ16と加工対象結晶基板20aとの間に配置される第2レンズ18と、で構成される。本実施形態では、第1レンズ16および第2レンズ18は、何れもレーザ光を円錐状に集光できるレンズとされている。そして、第1レンズ16と第2レンズ18との間隔調整により、集光点EPと集光点MPとの長さが調整可能になっており、集光レンズ15は補正環付きレンズとしての機能を有している。 The condensing lens 15 is composed of a first lens 16 that condenses light in the air, and a second lens 18 that is arranged between the first lens 16 and the crystal substrate 20a to be processed. In the present embodiment, the first lens 16 and the second lens 18 are both lenses capable of condensing laser light in a conical shape. The lengths of the condensing point EP and the condensing point MP can be adjusted by adjusting the distance between the first lens 16 and the second lens 18, and the condensing lens 15 functions as a lens with a correction ring. have.

第1レンズ16としては、球面または非球面の単レンズのほか、各種の収差補正や作動距離を確保するために組レンズを用いることが可能であり、NAが0.3〜0.85であることが好ましい。第2レンズ18としては、第1レンズ16よりも小さなNAのレンズで、例えば曲率半径が3〜5mm程度の凸ガラスレンズが、簡便に使用する観点で好ましい。 As the first lens 16, in addition to a spherical or aspherical single lens, a group lens can be used to correct various aberrations and secure a working distance, and the NA is 0.3 to 0.85. Is preferable. As the second lens 18, a lens having an NA smaller than that of the first lens 16, for example, a convex glass lens having a radius of curvature of about 3 to 5 mm is preferable from the viewpoint of easy use.

なお、第2レンズ18に代えて、レーザ光Bの収差増強材(例えば収差増強ガラス板)を配置することも可能である。 In addition, instead of the second lens 18, it is also possible to arrange an aberration enhancing material (for example, an aberration enhancing glass plate) of the laser beam B.

(基板加工方法)
以下、加工対象結晶基板20aが単結晶基板である例を挙げ、基板加工装置10を用いて本実施形態に係る基板加工方法を行うことをその効果も含めて説明する。
(Substrate processing method)
Hereinafter, an example in which the crystal substrate 20a to be processed is a single crystal substrate will be given, and the substrate processing method according to the present embodiment will be described using the substrate processing apparatus 10 including its effect.

本実施形態では、レーザ集光手段12を、加工対象単結晶基板20amの被照射面20u上に非接触に配置する第1工程を行う。そして、レーザ集光手段12により加工対象単結晶基板20amの内部にレーザ光Bを集光しつつ、レーザ光Bの集光位置Bfを加工対象単結晶基板20amのくり抜き対象部20bの周囲方向(外周方向)および厚み方向(図1、図2のZ方向)に変化させ、破断強度が低下した加工層22をくり抜き対象部20bの外周側に形成することで加工層含有基板20cとする第2工程を行う。本実施形態では、この第2工程では、加工対象結晶基板20a内部および少なくとも一方の加工対象結晶基板面近傍(表面近傍(上面近傍)または裏面近傍(下面近傍))で、レーザ光Bの集光位置Bfに生じる加工痕22cが加工対象結晶基板20aの結晶方位に沿って伸張しかつ加工対象結晶基板20aの異なる結晶方位に沿って伸張しないようにレーザ集光手段12の収差補正を調整する。 In the present embodiment, the first step of arranging the laser condensing means 12 on the irradiated surface 20u of the single crystal substrate 20am to be processed in a non-contact manner is performed. Then, while the laser light B is focused inside the processing target single crystal substrate 20am by the laser condensing means 12, the condensing position Bf of the laser light B is set in the peripheral direction of the hollowed out target portion 20b of the processing target single crystal substrate 20am. A second processed layer-containing substrate 20c is formed by forming a processed layer 22 having a reduced breaking strength on the outer peripheral side of the hollowed-out target portion 20b by changing in the outer peripheral direction) and the thickness direction (Z direction in FIGS. 1 and 2). Perform the process. In the present embodiment, in this second step, the laser beam B is focused inside the crystal substrate 20a to be processed and near at least one surface of the crystal substrate to be processed (near the front surface (near the upper surface) or near the back surface (near the lower surface)). The aberration correction of the laser condensing means 12 is adjusted so that the processing mark 22c generated at the position Bf extends along the crystal orientation of the processing target crystal substrate 20a and does not extend along the different crystal orientations of the processing target crystal substrate 20a.

以下、第2工程で加工層22を形成する手順を詳細に説明する。レーザ光Bを加工対象単結晶基板20amに照射する際、被照射面20uとは反対側の面(裏面20v)側から照射を開始できるように、回転ステージ11上に配置した加工対象単結晶基板20amにおける集光位置BfのZ軸方向位置を決定する。 Hereinafter, the procedure for forming the processed layer 22 in the second step will be described in detail. When irradiating the single crystal substrate 20am to be processed with the laser beam B, the single crystal substrate to be processed arranged on the rotating stage 11 so that the irradiation can be started from the surface (back surface 20v) opposite to the irradiated surface 20u. The Z-axis direction position of the focusing position Bf at 20 am is determined.

そして、まず回転ステージ11を少なくとも一回転させつつ、同心円に沿ってレーザ光Bを照射する。その後、基板加工装置10のZ軸方向に集光位置Bfを移動してレーザ光Bを同様にて同心円に沿って照射する。このときZ軸方向への集光位置Bfの移動が、加工対象単結晶基板20amの厚さ方向と同方向になっているので、加工層22を、被照射面20uに直交する短円筒状に形成することができる。 Then, first, the laser beam B is irradiated along the concentric circles while rotating the rotation stage 11 at least once. After that, the condensing position Bf is moved in the Z-axis direction of the substrate processing apparatus 10, and the laser beam B is similarly irradiated along the concentric circles. At this time, the movement of the condensing position Bf in the Z-axis direction is in the same direction as the thickness direction of the single crystal substrate 20am to be processed, so that the processed layer 22 is formed into a short cylinder orthogonal to the irradiated surface 20u. Can be formed.

この一連の動作を加工対象単結晶基板20amの被照射面20uの近傍にまで行うことにより、加工層22を完成させることができる。集光位置Bfのこの移動を行うには、レーザ集光手段12あるいは回転ステージ11の少なくとも一方を移動すればよい。 The processed layer 22 can be completed by performing this series of operations up to the vicinity of the irradiated surface 20u of the single crystal substrate 20am to be processed. In order to perform this movement of the focusing position Bf, at least one of the laser focusing means 12 and the rotating stage 11 may be moved.

本実施形態では、第2工程で、レーザ発振装置Jの出力を一定、すなわち、レーザ集光手段12に入射するレーザ光の出力を一定にしている。入射するレーザ光の出力は加工痕22cの伸張を抑制するために基板内部に加工痕22cが形成可能である下限の出力とすることが好ましい。 In the present embodiment, in the second step, the output of the laser oscillator J is constant, that is, the output of the laser light incident on the laser condensing means 12 is constant. The output of the incident laser beam is preferably set to the lower limit output at which the machining marks 22c can be formed inside the substrate in order to suppress the elongation of the machining marks 22c.

この下限の出力とは、基板厚さに対応して裏面20v(底面)側に集光位置Bfを合わせた時の補正環調整量(収差補正の調整量)に基づき、加工痕22cの基板厚さ方向長さK(図6参照)が10μm以下、好ましくは3μm〜10μm、さらに好ましくは3μm〜7μmで形成できる出力である。 This lower limit output is the substrate thickness of the processing mark 22c based on the correction ring adjustment amount (aberration correction adjustment amount) when the condensing position Bf is adjusted to the back surface 20v (bottom surface) side corresponding to the substrate thickness. The output can be formed with a longitudinal length K (see FIG. 6) of 10 μm or less, preferably 3 μm to 10 μm, and more preferably 3 μm to 7 μm.

そして、集光位置Bfを段階的に加工対象単結晶基板20amの表面側に移動しつつ長さKが10μm以下(好ましくは3μm〜7μm)の加工痕22cを形成していく。その際、加工対象結晶基板20aの結晶方位(例えば[100]方位)に沿って加工痕22cが伸張し、かつ加工対象結晶基板20aの異なる結晶方位(例えば[111]方位や[110]方位)に沿って加工痕22cが伸張しないように加工痕22cを形成する。なお、加工痕長さが3μmを下回った場合(例えば2μmである場合)では、形成した加工痕が深さ方向に連結し難いため、良好なくり抜きを行い難い。 Then, the light-collecting position Bf is gradually moved to the surface side of the single crystal substrate 20 am to be processed, and the processing marks 22c having a length K of 10 μm or less (preferably 3 μm to 7 μm) are formed. At that time, the processing marks 22c extend along the crystal orientation (for example, [100] orientation) of the crystal substrate 20a to be processed, and the different crystal orientations of the crystal substrate 20a to be processed (for example, [111] orientation and [110] orientation). The machining mark 22c is formed so that the machining mark 22c does not extend along the line. When the processing mark length is less than 3 μm (for example, when it is 2 μm), it is difficult to connect the formed processing marks in the depth direction, so that it is difficult to perform good scraping.

加工痕22cを形成していく際には、予め加工痕形成状態を確認して条件選定を行い加工条件を決定することが望ましい。 When forming the machining marks 22c, it is desirable to confirm the machining marks formation state in advance, select the conditions, and determine the machining conditions.

具体的には、レーザ照射面側の基板表面を基準としてレーザ集光手段を基板内部方向に移動し基板内部に焦点を形成させる。この移動量をデフォーカス量(DF量)として定義する。次に補正環調整量を大きくし基板裏面側に加工痕を形成し、徐々に補正環調整量を小さくし加工痕形成位置を基板表面方向に移動していく。このとき、補正環の調整は加工痕長さが10μm以下、好ましくは3μm〜7μmで形成できる範囲においては補正環調整量を変更しなくてもよい。一方、補正環調整量に対して球面収差が補正されレーザ光のエネルギー密度がもっとも大きくなる深さ位置が生じ加工痕が長くなる。この場合においても加工痕が10μm以下、好ましくは3μm〜7μmとなるようにレーザ出力を設定しておくことが好ましい。なお、この時のレーザ出力およびDF量は上記加工状態を得ることができるように適宜選定される。さらに、レーザ出力はパルスレーザのパルスエネルギーとして設定することが望ましい。 Specifically, the laser condensing means is moved toward the inside of the substrate with reference to the surface of the substrate on the laser irradiation surface side to form a focal point inside the substrate. This movement amount is defined as the defocus amount (DF amount). Next, the correction ring adjustment amount is increased to form a machining mark on the back surface side of the substrate, and the correction ring adjustment amount is gradually reduced to move the machining mark formation position toward the substrate surface. At this time, the correction ring adjustment amount does not have to be changed within the range in which the processing mark length can be formed within 10 μm, preferably 3 μm to 7 μm. On the other hand, the spherical aberration is corrected with respect to the correction ring adjustment amount, a depth position where the energy density of the laser light is maximized is generated, and the processing mark becomes long. Even in this case, it is preferable to set the laser output so that the processing mark is 10 μm or less, preferably 3 μm to 7 μm. The laser output and the amount of DF at this time are appropriately selected so that the above-mentioned processing state can be obtained. Further, it is desirable to set the laser output as the pulse energy of the pulse laser.

このように加工痕を形成していくことで、良好な品質のくり抜き結晶基板を、加工対象結晶基板20aの結晶方位への加工痕22cの伸張によって短時間で効率良く得ることができる。そのため、集光位置Bfに対して補正環を調整(第1レンズ16と第2レンズ18との間隔を制御)することによって球面収差を補正して各集光位置Bfで長さKが10μm以下の加工痕22cを所定位置に形成していく。 By forming the processing marks in this way, a hollow crystal substrate of good quality can be efficiently obtained in a short time by extending the processing marks 22c in the crystal orientation of the crystal substrate 20a to be processed. Therefore, the spherical aberration is corrected by adjusting the correction ring with respect to the focusing position Bf (controlling the distance between the first lens 16 and the second lens 18), and the length K is 10 μm or less at each focusing position Bf. The processing marks 22c of the above are formed at predetermined positions.

加工対象単結晶基板20amの裏面20v(底面)側への最初の集光位置Bfは、レーザ光Bの照射により形成される加工層22が加工対象単結晶基板20amの裏面20vに亀裂やアブレーションなどによる無用なダメージ(特にくり抜き対象部20bへのダメージ)を与えない所定範囲内に設定する。 At the first condensing position Bf of the single crystal substrate 20am to be processed toward the back surface 20v (bottom surface) side, the processing layer 22 formed by irradiation with the laser beam B has cracks or ablation on the back surface 20v of the single crystal substrate 20am to be processed. It is set within a predetermined range that does not cause unnecessary damage (particularly damage to the hollowed-out target portion 20b).

加工層22には、レーザ光Bの集光によって形成された加工痕22cが、一定の間隔で規則的に配列されている。この加工痕22cを形成する間隔に関しては、基板平面方向(被照射面20uや裏面20vに平行な方向)ではレーザ光Bの発振繰り返し周波数と回転ステージ11の回転速度(すなわち周速)との関係で決定され、基板高さ(深さ)方向では集光位置BfのZ軸方向の移動量により決定される。加工層22は上記のように所定間隔にレーザ光Bを照射して、加工痕22cが断続的に形成された領域として得られる。この時レーザ光Bは、例えばパルス幅が1μs以下のパルスレーザ光からなり、300nm以上の波長が選択され、例えば加工対象単結晶基板20amがシリコンウエハの場合は、1000nm以上の波長のYAGレーザ等が好適に使用される。 The processing marks 22c formed by condensing the laser beam B are regularly arranged on the processing layer 22 at regular intervals. Regarding the interval for forming the processing marks 22c, the relationship between the oscillation repetition frequency of the laser beam B and the rotation speed (that is, peripheral speed) of the rotation stage 11 in the substrate plane direction (direction parallel to the irradiated surface 20u and the back surface 20v). In the substrate height (depth) direction, it is determined by the amount of movement of the condensing position Bf in the Z-axis direction. The processed layer 22 is irradiated with the laser beam B at predetermined intervals as described above, and is obtained as a region where the processed marks 22c are intermittently formed. At this time, the laser beam B is composed of, for example, a pulsed laser beam having a pulse width of 1 μs or less, and a wavelength of 300 nm or more is selected. For example, when the single crystal substrate 20 am to be processed is a silicon wafer, a YAG laser having a wavelength of 1000 nm or more or the like is selected. Is preferably used.

そして、被照射面20u近傍では、くり抜き結晶基板の欠けや割れを防ぐために、加工痕22cが基板表面に露出しない、すなわち基板表面にレーザ光Bによるアブレーションが生じない状態で形成することが必要である。そのためにレーザ光Bの出力を一定に保った状態で、集光位置Bfにおいてレーザ光Bの焦点を外すように補正環を調整(第1レンズ16と第2レンズ18との間隔を調整)する。 In the vicinity of the irradiated surface 20u, in order to prevent the hollow crystal substrate from being chipped or cracked, it is necessary to form the processing marks 22c in a state where the processing marks 22c are not exposed on the substrate surface, that is, the substrate surface is not ablated by the laser beam B. is there. Therefore, while keeping the output of the laser beam B constant, the correction ring is adjusted so as to defocus the laser beam B at the condensing position Bf (the distance between the first lens 16 and the second lens 18 is adjusted). ..

この後、くり抜き対象部20bを加工層含有基板20cから切り離してくり抜き単結晶基板20dを得る。 After that, the hollowed-out target portion 20b is separated from the processed layer-containing substrate 20c to obtain a hollowed-out single crystal substrate 20d.

ここで、本実施形態では、加工対象単結晶基板20amの裏面20v(底面)側への最初の集光位置Bfは、レーザ光Bの照射により形成される加工層22が加工対象単結晶基板20amの裏面20vに亀裂やアブレーションなどによる無用なダメージ(特にくり抜き対象部20bへのダメージ)を与えない位置に設定している。従って、使用者が加工層含有基板20cを裏面側が広がるように撓ませた際、裏面側で加工痕22cから無用なクラックが発生してくり抜き対象部20bに損傷が生じることを効果的に抑えることができる。 Here, in the present embodiment, the first condensing position Bf of the single crystal substrate 20am to be processed toward the back surface 20v (bottom surface) side is such that the processing layer 22 formed by irradiation with the laser beam B is the single crystal substrate 20am to be processed. The back surface 20v is set to a position that does not cause unnecessary damage (particularly damage to the hollowed-out target portion 20b) due to cracks or ablation. Therefore, when the user bends the processed layer-containing substrate 20c so that the back surface side expands, it is possible to effectively suppress the occurrence of unnecessary cracks from the processing marks 22c on the back surface side and damage to the hollowed-out target portion 20b. Can be done.

そして本実施形態では、レーザ発振装置Jの出力を一定にし、被照射面20u近傍では、被照射面20uに近いほど、集光位置Bfにおいてレーザ光Bの焦点を外すように補正環を調整(第1レンズ16と第2レンズ18との間隔を調整)している。このことにより、被照射面20u近傍において加工痕22cが伸張することを抑制し、基板表面に加工痕22cが露出しない状態を得ることができる。なお、この補正環の調整は基板厚さに対してレーザ光Bの焦点が外れる設定に任意に選択できる。 Then, in the present embodiment, the output of the laser oscillator J is made constant, and the correction ring is adjusted so that the closer to the irradiated surface 20u and the closer to the irradiated surface 20u, the more the laser beam B is out of focus at the condensing position Bf ( The distance between the first lens 16 and the second lens 18 is adjusted). As a result, it is possible to suppress the extension of the processing marks 22c in the vicinity of the irradiated surface 20u and obtain a state in which the processing marks 22c are not exposed on the substrate surface. The adjustment of the correction ring can be arbitrarily selected to set the laser beam B to be out of focus with respect to the substrate thickness.

従って、被照射面20u近傍の加工層部分では、他の加工層部分に比べ、加工痕22cの周囲に生じる意図しない損傷(亀裂)や歪が相対的に小さい。よって、使用者がくり抜き対象部20bをくり抜いた際、被照射面20u近傍で加工痕22cから無用なクラックが発生してくり抜き単結晶基板20dに損傷が生じることを大幅に抑えることができる。 Therefore, in the processed layer portion near the irradiated surface 20u, unintended damage (cracks) and strain generated around the processed mark 22c are relatively small as compared with the other processed layer portions. Therefore, when the user hollows out the hollowed-out target portion 20b, it is possible to significantly prevent the hollowed-out single crystal substrate 20d from being damaged due to unnecessary cracks generated from the processing marks 22c in the vicinity of the irradiated surface 20u.

よって、本実施形態により、加工対象単結晶基板20amから欠け(チッピング)のないくり抜き単結晶基板20dを短時間で容易に得ることができる。なお、得られたくり抜き単結晶基板20dの外周面には、必要に応じて研磨等の加工を行う。 Therefore, according to this embodiment, a hollowed-out single crystal substrate 20d without chipping can be easily obtained from the processing target single crystal substrate 20am in a short time. The outer peripheral surface of the obtained hollowed-out single crystal substrate 20d is subjected to processing such as polishing as necessary.

ここで、被照射面20u近傍とは、このようなレーザ光照射によって、加工層22形成後の人手によるくり抜き作業を無用なチッピングを生じさせずに行うことができる被照射面付近の部位のことであり、具体的には被照射面(基板表面)から内部に100μmまでの範囲であり、好適には基板表面から50μmまでの範囲である。この範囲において補正環調整によりレーザ光Bの焦点を外すことで、加工痕の結晶方位と異なる方向への伸張を防ぐとともにアブレーションを発生させずに加工痕を形成することが必要である。 Here, the vicinity of the irradiated surface 20u is a portion near the irradiated surface where the manual hollowing work after the formation of the processed layer 22 can be performed without causing unnecessary chipping by such laser light irradiation. Specifically, it is in the range of up to 100 μm from the irradiated surface (the surface of the substrate) to the inside, preferably in the range of up to 50 μm from the surface of the substrate. In this range, it is necessary to defocus the laser beam B by adjusting the correction ring to prevent the processing marks from extending in a direction different from the crystal orientation of the processing marks and to form the processing marks without causing ablation.

単結晶基板の寸法が使用予定の寸法よりも大きい場合、このようにして、この単結晶基板を加工対象単結晶基板20amとし、加工対象単結晶基板20amよりも小さい寸法のくり抜き単結晶基板20dを得ることで加工対象単結晶基板20amを再利用することができ、資源の有効活用が図られる。 When the size of the single crystal substrate is larger than the size to be used, the single crystal substrate is set as the target single crystal substrate 20 am in this way, and the hollowed out single crystal substrate 20 d having a size smaller than the target single crystal substrate 20 am is used. By obtaining it, the single crystal substrate 20 am to be processed can be reused, and resources can be effectively utilized.

また、本実施形態では、レーザ集光手段12と加工対象単結晶基板20amの裏面20vとが離れる方向の移動では、基板厚み方向と同方向に移動させている。従って、加工層22が短円筒状に形成されているので、得られたくり抜き単結晶基板20dの外周は円筒外周状となっており、使い勝手が良い。ここで本実施形態では、加工層含有基板20cの被照射面20u近傍では、レーザ光Bの出力を一定に保った状態で、集光位置Bfにおいてレーザ光Bの焦点を外すように補正環を調整(第1レンズ16と第2レンズ18との間隔を調整)することで、集光位置Bfにおいて生じる加工痕22cが加工対象単結晶基板20amの結晶方位に沿って伸張しかつ加工対象単結晶基板20amの異なる結晶方位に沿って伸張しないようにレーザ集光手段12の収差補正を調整して繋げるようにレーザ光を照射することで加工痕22cが形成される。 Further, in the present embodiment, when the laser condensing means 12 and the back surface 20v of the single crystal substrate 20am to be processed are moved away from each other, they are moved in the same direction as the substrate thickness direction. Therefore, since the processed layer 22 is formed in a short cylindrical shape, the outer circumference of the obtained hollowed-out single crystal substrate 20d has a cylindrical outer circumference, which is convenient. Here, in the present embodiment, in the vicinity of the irradiated surface 20u of the processed layer-containing substrate 20c, the correction ring is provided so as to defocus the laser light B at the condensing position Bf while keeping the output of the laser light B constant. By adjusting (adjusting the distance between the first lens 16 and the second lens 18), the processing marks 22c generated at the condensing position Bf extend along the crystal orientation of the processing target single crystal substrate 20am and the processing target single crystal. The processing mark 22c is formed by irradiating the laser beam so as to adjust the aberration correction of the laser condensing means 12 so as not to extend along the different crystal orientations of the substrate 20am and to connect the laser light.

その上、加工対象単結晶基板20amの裏面20v側への最初の集光位置Bfは、裏面20vに亀裂やアブレーションなどによる無用なダメージを与えないように裏面20vから所定範囲内の基板厚さ位置に設定されている。 In addition, the first condensing position Bf of the single crystal substrate 20am to be processed toward the back surface 20v is a substrate thickness position within a predetermined range from the back surface 20v so as not to cause unnecessary damage to the back surface 20v due to cracks or ablation. Is set to.

従って、加工層22の形状をチッピングが発生し難い形状(例えば、裏面側に広がるテーパ状)にせずに単に短円筒状としても、加工痕22cから無用なクラックが発生することが大幅に抑えられている。 Therefore, even if the shape of the processed layer 22 is not made into a shape that is unlikely to cause chipping (for example, a tapered shape that spreads to the back surface side) and is simply made into a short cylinder, unnecessary cracks are significantly suppressed from the processing marks 22c. ing.

また、本実施形態では、第2工程で、レーザ発振装置Jの出力を一定、すなわち、レーザ集光手段12に入射するレーザ光の出力を一定にしている。従って、集光位置BfがZ軸方向に移動することに応じたパラメータの変更を補正環の調整(集光レンズ15の収差補正の調整)のみにしており、収差補正制御手段13で制御することによってこれらの効果を得ることが可能である。収差補正制御手段13による収差補正の調整状態は、くり抜き時における無用なクラックの発生し難さ、加工層22の形成のし易さ、などを考慮して適切な値に設定する。 Further, in the present embodiment, in the second step, the output of the laser oscillator J is constant, that is, the output of the laser light incident on the laser condensing means 12 is constant. Therefore, the parameter change according to the movement of the condensing position Bf in the Z-axis direction is limited to the adjustment of the correction ring (adjustment of the aberration correction of the condensing lens 15), and is controlled by the aberration correction control means 13. It is possible to obtain these effects. The adjustment state of the aberration correction by the aberration correction control means 13 is set to an appropriate value in consideration of the difficulty of generating unnecessary cracks at the time of hollowing out, the ease of forming the processed layer 22 and the like.

また、基板加工装置10は、回転ステージ11の回転中心軸Csとレーザ集光手段12によるレーザ光Bの加工対象単結晶基板20amへの照射中心軸Cbとの距離rを変える半径方向距離変更手段を備えている。従って、くり抜き対象部20bの半径に合わせて加工層22の形成位置を変更することが容易にできる。 Further, the substrate processing apparatus 10 is a radial distance changing means for changing the distance r between the rotation center axis Cs of the rotation stage 11 and the irradiation center axis Cb of the laser beam B on the single crystal substrate 20am to be processed by the laser condensing means 12. It has. Therefore, the forming position of the processed layer 22 can be easily changed according to the radius of the hollowed-out target portion 20b.

また、第2工程では、図6に示すように、レーザ光Bの集光によって加工層22に形成される加工痕22cの基板厚み方向長さKを10μm以下(さらに好ましくは3μm〜7μm)としている。これにより、加工対象単結晶基板20amの上下方向(結晶方位[100]方向)に加工痕22cが良好に伸張しやすい。 Further, in the second step, as shown in FIG. 6, the length K in the substrate thickness direction of the processing marks 22c formed on the processing layer 22 by condensing the laser beam B is set to 10 μm or less (more preferably 3 μm to 7 μm). There is. As a result, the processing marks 22c are likely to be satisfactorily stretched in the vertical direction (crystal orientation [100] direction) of the single crystal substrate 20am to be processed.

なお、第1レンズ16と第2レンズ18との間隔調整、すなわち、収差補正環としての機能によるレーザ光Bの調整を変化させつつ、レーザ光Bの出力を変化させてもよい。これにより、加工痕22cの寸法や加工痕22c周囲の歪を更に精度良く制御することができる。 The output of the laser light B may be changed while changing the distance adjustment between the first lens 16 and the second lens 18, that is, the adjustment of the laser light B by the function as an aberration correction ring. As a result, the dimensions of the machining marks 22c and the strain around the machining marks 22c can be controlled more accurately.

また、図4では、加工層22には加工痕22cが一列に配置されているように描いているが、実際には、加工層22には複数列にわたって加工痕22cが散りばめられるようにレーザ光Bを照射してもよい。これにより、くり抜き対象部20bを加工層含有基板20cからくり抜く際の作業が更に容易になる。 Further, in FIG. 4, the machined layer 22 is drawn so that the machined marks 22c are arranged in a single row, but in reality, the machined layer 22 is irradiated with laser light so that the machined marks 22c are scattered over a plurality of rows. You may irradiate B. As a result, the work of hollowing out the hollowed-out target portion 20b from the processed layer-containing substrate 20c becomes easier.

また、本実施形態に係る基板加工方法の説明では、加工対象単結晶基板20amが単結晶基板である例で説明したが、単結晶基板以外であっても、本実施形態に係る基板加工方法が適用可能である。 Further, in the description of the substrate processing method according to the present embodiment, the example in which the single crystal substrate 20 am to be processed is a single crystal substrate has been described, but the substrate processing method according to the present embodiment may be used even if the single crystal substrate is other than the single crystal substrate. Applicable.

また、本実施形態では、基板加工方法として、本実施形態の基板加工装置10を用いて加工層含有基板20cにする例で説明したが、基板加工装置10を用いずに他の装置を用いて加工層含有基板20cを製造することも勿論可能である。 Further, in the present embodiment, as a substrate processing method, an example of forming a processed layer-containing substrate 20c by using the substrate processing apparatus 10 of the present embodiment has been described, but another apparatus is used without using the substrate processing apparatus 10. Of course, it is also possible to manufacture the processed layer-containing substrate 20c.

<実験例1>
本発明者は、上記実施形態に係る基板加工方法の一実施例(以下、実施例1という)により、上記実施形態の基板加工装置10を用い、結晶方位がそれぞれ[100]、[110]で、厚さ625μmのφ200mmの単結晶シリコンウエハを加工対象単結晶基板として、以下の実験を行った。
<Experimental example 1>
According to one embodiment of the substrate processing method according to the above embodiment (hereinafter referred to as Example 1), the present inventor uses the substrate processing apparatus 10 of the above embodiment and has crystal orientations of [100] and [110], respectively. The following experiment was carried out using a single crystal silicon wafer having a thickness of 625 μm and a diameter of 200 mm as a single crystal substrate to be processed.

レーザ発振器としては以下の装置を用いた。
対物レンズ :補正環機能付き100倍、NAは0.85
(オリンパス社製のLCPLN100XIRを使用)
波長(nm) :1064
パルス幅(ns) :190
パルスエネルギー(μJ):3.0
The following equipment was used as the laser oscillator.
Objective lens: 100x with correction ring function, NA is 0.85
(Uses LCPLN100XIR manufactured by Olympus)
Wavelength (nm): 1064
Pulse width (ns): 190
Pulse energy (μJ): 3.0

加工条件としては以下のように行った。
補正環調整量 :0.7
(補正環目盛値)
デフォーカス量 :−10、−30、−50
(DF量、μm)
照射間隔(μm) :2.0
The processing conditions were as follows.
Correction ring adjustment amount: 0.7
(Correction ring scale value)
Defocus amount: -10, -30, -50
(DF amount, μm)
Irradiation interval (μm): 2.0

各照射条件で照射した後、レーザ照射方向に沿って基板断面を露出させ、レーザ顕微鏡(電子顕微鏡)で観察した。撮像画像を図7に示す。図7から判るように、加工対象基板の結晶方位に関係なくDF量が大きくなるに従い、すなわち基板の深い位置に行くに従い、加工痕長さは短くなる傾向にある(なお、加工痕の深さ位置とは、加工痕の上端と下端との中間位置のことである)。[110]基板ではDF量が−10μmの場合には斜めに伸びるクラックが発生しており結晶方位と異なる方向に加工痕が拡がってしまう。これは[111]方向へのクラック伸張が生じ易いためである。しかし、DF量を深くし加工痕を短くすることによりこの現象を防ぎ結晶方位に沿った加工痕形成が可能となる。 After irradiation under each irradiation condition, the cross section of the substrate was exposed along the laser irradiation direction and observed with a laser microscope (electron microscope). The captured image is shown in FIG. As can be seen from FIG. 7, the processing mark length tends to become shorter as the amount of DF increases regardless of the crystal orientation of the substrate to be processed, that is, as the depth of the substrate increases (note that the depth of the processing marks tends to decrease). The position is the intermediate position between the upper end and the lower end of the machining mark). When the amount of DF is −10 μm on the substrate, cracks extending diagonally are generated and the processing marks spread in a direction different from the crystal orientation. This is because crack extension in the [111] direction is likely to occur. However, by increasing the amount of DF and shortening the processing marks, this phenomenon can be prevented and processing marks can be formed along the crystal orientation.

<実験例2>
補正環を調整せずにDF量を増大していくと、形成される加工痕長さが安定し難く、かつ、基板の深い位置に加工痕が形成され難い。そこで本発明者は、基板深さ方向の各位置で加工痕長さが10μm以下となる照射条件を探ることを意図して、レーザ出力を一定、すなわちパルスエネルギーを一定の条件にして補正環を変化させた場合の加工痕形成状態を評価した。
<Experimental example 2>
If the amount of DF is increased without adjusting the correction ring, it is difficult to stabilize the length of the machined marks formed and it is difficult to form the machined marks at a deep position on the substrate. Therefore, the present inventor intends to search for irradiation conditions in which the machining mark length is 10 μm or less at each position in the substrate depth direction, and sets the laser output constant, that is, the pulse energy to a constant condition to provide a correction ring. The state of processing mark formation when changed was evaluated.

レーザ発振器としては以下の装置を用いた。
対物レンズ :補正環機能付き100倍、NAは0.85
(オリンパス社製のLCPLN100XRを使用)
波長(nm) :1064
パルス幅(ns) :190
周波数(kHz) :500
パルスエネルギー(μJ):3.0
The following equipment was used as the laser oscillator.
Objective lens: 100x with correction ring function, NA is 0.85
(Uses Olympus LCPLN100XR)
Wavelength (nm): 1064
Pulse width (ns): 190
Frequency (kHz): 500
Pulse energy (μJ): 3.0

加工条件としては以下のように行った。
補正環調整量 :0.0、0.1、0.2、0.3、0.4、0.5、0.6、0.7、
0.8、0.9、1.0
DF量(μm) :-90、-80、-70、-60、-50、-40、-30、-20、-10
照射間隔(μm) :2.0
The processing conditions were as follows.
Correction ring adjustment amount: 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7,
0.8, 0.9, 1.0
DF amount (μm): -90, -80, -70, -60, -50, -40, -30, -20, -10
Irradiation interval (μm): 2.0

そして各照射条件で照射した後、レーザ照射方向に沿って基板断面を露出させ、加工痕長さを測定した。測定結果を図8、図9に示す。補正環を一定の状態にしてDF量を変化させると深い位置での加工痕形成ができなくなってくるが、深い位置に対する補正環調整量(深い位置への補正環による補正量)を大きくすることで、より深い位置にも加工痕を形成できることが分かる。また、深い位置になるに従い加工痕長さも短くなるが、これは球面収差が補正されエネルギー密度が高くなるためであると考えられる。このようにレーザ出力すなわちパルスエネルギーを一定にした状態で補正環調整量(補正環の目盛値)のみを変化させれば目標とする「加工痕長さ10μm以下」の加工痕を深さ方向に連続的に形成できる。なお、この時のレーザ出力は上記状態を発現するために適正に選択すればよい。 Then, after irradiation under each irradiation condition, the cross section of the substrate was exposed along the laser irradiation direction, and the processing mark length was measured. The measurement results are shown in FIGS. 8 and 9. If the correction ring is kept constant and the DF amount is changed, it becomes impossible to form processing marks at a deep position, but the correction ring adjustment amount for a deep position (correction amount by the correction ring for a deep position) should be increased. Therefore, it can be seen that processing marks can be formed even at deeper positions. Further, the processing mark length becomes shorter as the position becomes deeper, which is considered to be because the spherical aberration is corrected and the energy density becomes higher. In this way, if only the correction ring adjustment amount (scale value of the correction ring) is changed while the laser output, that is, the pulse energy is constant, the target processing mark with a processing mark length of 10 μm or less can be obtained in the depth direction. Can be formed continuously. The laser output at this time may be appropriately selected in order to exhibit the above state.

<実験例3>
上記実施形態に係る基板加工方法の一実施例(以下、実施例2という)により、破断強度が低下した加工層22を形成して加工層含有基板20cとした。
<Experimental example 3>
According to one embodiment of the substrate processing method according to the above embodiment (hereinafter referred to as Example 2), a processed layer 22 having a reduced breaking strength was formed to obtain a processed layer-containing substrate 20c.

その際、加工対象単結晶基板20amの裏面20v(底面)側への最初の集光位置Bfは、レーザ光Bの照射により形成される加工層22が加工対象単結晶基板20amの裏面20vに亀裂やアブレーションなどによる無用なダメージ(特にくり抜き対象部20bへのダメージ)を与えない所定範囲内に設定し、加工痕22cが形成される下限のレーザ出力で照射した(図10参照)。 At that time, at the first condensing position Bf toward the back surface 20v (bottom surface) side of the processing target single crystal substrate 20am, the processing layer 22 formed by irradiation with the laser beam B cracks in the back surface 20v of the processing target single crystal substrate 20am. It was set within a predetermined range that does not cause unnecessary damage (particularly damage to the hollowed-out target portion 20b) due to ablation or the like, and was irradiated with the lower limit laser output at which the machining mark 22c is formed (see FIG. 10).

そして、集光位置Bfを徐々に上方へ移動させていくことで、破断強度が低下した加工層22をくり抜き対象部20bの外周側に形成した。この移動により、被照射面20uから集光位置までの距離(基板厚み方向の距離)が徐々に短くなるので、移動に伴って収差補正をしないと集光が不十分となる(図11参照)。このため、上記実施形態のように収差補正を調整していくことで十分に集光させつつ集光位置Bfを移動させ、加工痕22cの基板厚さ方向長さKが10μm以下となるように収差補正を調整して加工対象単結晶基板20amにレーザ光を照射した(図12参照)。 Then, by gradually moving the light collecting position Bf upward, the processed layer 22 having reduced breaking strength was formed on the outer peripheral side of the hollowed-out target portion 20b. Due to this movement, the distance from the irradiated surface 20u to the condensing position (distance in the thickness direction of the substrate) gradually becomes shorter, so that condensing becomes insufficient unless aberration correction is performed along with the movement (see FIG. 11). .. Therefore, by adjusting the aberration correction as in the above embodiment, the condensing position Bf is moved while sufficiently condensing the light so that the length K of the processing mark 22c in the substrate thickness direction is 10 μm or less. After adjusting the aberration correction, the single crystal substrate 20 am to be processed was irradiated with laser light (see FIG. 12).

そして、くり抜き対象部20bをくり抜き、破断面を電子顕微鏡で撮像した。撮像図から、加工対象単結晶基板20amの結晶方位に沿って伸張しかつ加工対象単結晶基板20amの異なる結晶方位に沿って伸張しないように加工痕22cが繋がっていることが確認された。 Then, the hollowed-out target portion 20b was hollowed out, and the fracture surface was imaged with an electron microscope. From the image pickup, it was confirmed that the processing marks 22c were connected so as to extend along the crystal orientation of the processing target single crystal substrate 20am and not to extend along the different crystal orientations of the processing target single crystal substrate 20am.

なお、補正環を用いない場合には、図13(a)および(b)に示すように、加工対象単結晶基板20am内にレーザ光が入射することで、レーザ光の入射位置の違いによって焦点が基板厚み方向に長くなってしまうが(図13(b)参照)、補正環を用いた場合には、図14に示すように、加工対象単結晶基板20am内にレーザ光が入射してレーザ光の入射角度が変化しても、焦点(集光位置Bf)が基板厚み方向に長くなることを予め防止して入射させることが可能になる。 When the correction ring is not used, as shown in FIGS. 13A and 13B, the laser beam is incident on the single crystal substrate 20am to be processed, and the laser beam is focused due to the difference in the incident position of the laser beam. Is longer in the thickness direction of the substrate (see FIG. 13B), but when a correction ring is used, as shown in FIG. 14, a laser beam is incident on the single crystal substrate 20am to be processed and the laser is used. Even if the incident angle of light changes, it is possible to prevent the focal point (condensing position Bf) from becoming longer in the substrate thickness direction in advance so that the light can be incident.

本実験例のように集光位置Bfが基板厚み方向位置に移動する場合には、収差補正を調整していくことで十分に集光させつつ集光位置Bfを移動させることによって、加工痕22cの基板厚さ方向長さKが長くなることを充分に抑え易い。 When the condensing position Bf moves to the position in the thickness direction of the substrate as in this experimental example, the processing mark 22c is obtained by moving the condensing position Bf while sufficiently condensing by adjusting the aberration correction. It is easy to sufficiently suppress that the length K in the thickness direction of the substrate becomes long.

<実験例4>
本発明者は、上記実施形態に係る基板加工方法の一実施例(以下、実施例3という)により、以下の条件で加工対象単結晶基板に加工を行った。その際、集光位置Bfを被照射面20uから基板厚み方向に20μmまでの位置としており、被照射面20uから20μmよりも浅い位置にはレーザ光が集光しないようにした。レーザ発振器ではファイバーレーザを用いた。
対物レンズ :補正環機能付き100倍、NAは0.85
(オリンパス社製のLCPLN100XRを使用)
単結晶基板 :単結晶シリコンウエハ、結晶方位[100]
波長(nm) :1064
出力(W) :0.6
発信周波数(kHz) :500
パルス幅(ns) :190
ドットピッチ(μm) :2
ラインピッチ(μm) :2
補正環調整量 :0.0〜0.7
<Experimental Example 4>
The present inventor has processed a single crystal substrate to be processed under the following conditions according to an embodiment of the substrate processing method according to the above embodiment (hereinafter referred to as Example 3). At that time, the condensing position Bf was set to a position from the irradiated surface 20u to 20 μm in the substrate thickness direction, and the laser beam was prevented from condensing at a position shallower than 20 μm from the irradiated surface 20u. A fiber laser was used as the laser oscillator.
Objective lens: 100x with correction ring function, NA is 0.85
(Uses Olympus LCPLN100XR)
Single crystal substrate: Single crystal silicon wafer, crystal orientation [100]
Wavelength (nm): 1064
Output (W): 0.6
Transmission frequency (kHz): 500
Pulse width (ns): 190
Dot pitch (μm): 2
Line pitch (μm): 2
Correction ring adjustment amount: 0.0 to 0.7

本実験例では、焦点位置(加工位置。裏面20vからの基板厚み方向の距離)に応じて補正環調整量を以下のように設定した。
焦点位置(μm) 補正環調整量
0〜100 0.7
100〜150 0.0
150〜200 0.1
200〜250 0.2
250〜300 0.3
300〜350 0.4
350〜425 0.5
425〜500 0.6
500〜625 0.7
In this experimental example, the correction ring adjustment amount was set as follows according to the focal position (processing position, the distance in the substrate thickness direction from the back surface 20v).
Focus position (μm) Correction ring adjustment amount
0-100 0.7
100-150 0.0
150-200 0.1
200-250 0.2
250-300 0.3
300-350 0.4
350-425 0.5
425-500 0.6
500-625 0.7

そして、加工層22近辺の断面を電子顕微鏡で撮像した。撮像図から判断した結果、実施例3では、加工層22近辺の被照射面20uにはアブレーション等の損傷は生じていなかった。従って、くり抜き対象部をくり抜く際、チッピングが生じることなくくり抜くことができる。 Then, the cross section in the vicinity of the processed layer 22 was imaged with an electron microscope. As a result of judging from the image pickup, in Example 3, the irradiated surface 20u near the processed layer 22 was not damaged such as ablation. Therefore, when the hollowed-out target portion is hollowed out, it can be hollowed out without chipping.

また、この後、くり抜き対象部をくり抜いた。図15は、実施例3によって得られた加工層含有基板からくり抜き対象部をくり抜いたことを説明する写真図である。くり抜き対象部にチッピングが生じることなくくり抜くことができた。 After that, the hollowed-out target portion was hollowed out. FIG. 15 is a photographic diagram illustrating that the hollowed-out target portion is hollowed out from the processed layer-containing substrate obtained in Example 3. It was possible to hollow out the hollowed-out target part without chipping.

また、本発明者は、比較のための一例(以下、比較例1という)として、被照射面20uまでレーザ光の集光位置を移動させて基板加工を行った。そして、加工層近辺の断面を電子顕微鏡で撮像した。撮像図を図16に示す。図16から判るように、比較例1では、加工層近辺の被照射面20uにはアブレーションが生じていた。従って、くり抜き対象部をくり抜く際、チッピングが生じる。 Further, as an example for comparison (hereinafter referred to as Comparative Example 1), the present inventor processed the substrate by moving the focusing position of the laser beam to the irradiated surface 20u. Then, the cross section near the processed layer was imaged with an electron microscope. An image is shown in FIG. As can be seen from FIG. 16, in Comparative Example 1, ablation occurred on the irradiated surface 20u near the processed layer. Therefore, chipping occurs when the hollowed-out target portion is hollowed out.

[第2実施形態]
次に、第2実施形態を説明する。図17は、本実施形態に係る基板加工方法により製造した加工層含有基板を示す模式的な側面断面図である。本実施形態では、第1実施形態と同様、加工対象結晶基板20aが単結晶基板である例を挙げて説明する。
[Second Embodiment]
Next, the second embodiment will be described. FIG. 17 is a schematic side sectional view showing a processed layer-containing substrate manufactured by the substrate processing method according to the present embodiment. In the present embodiment, as in the first embodiment, an example in which the crystal substrate 20a to be processed is a single crystal substrate will be described.

本実施形態では、第1実施形態に比べ、第2工程で加工対象単結晶基板20amに加工層22を形成する際、加工層22のうち加工対象単結晶基板20amの裏面(底面)側を構成する加工層裏面方部22vでは、裏面20vから離れるにつれて、回転ステージ11の回転中心軸Csとレーザ集光手段12の照射中心軸Cbとの距離rを徐々に広げ、加工層裏面方部22vよりも被照射面20u側(表面側)ではこの距離を一定にしている(図17参照)。そして、このように徐々に広げることで、加工層裏面方部22vの外周側を、加工対象単結晶基板20amの裏面20vから離れるにつれて径が徐々に大きくなるR面状(断面円弧状)に形成している。この結果、加工層裏面方部22vは半径Nの面取り形状(すなわち、くり抜き対象部20bのうち加工層裏面方部22vの内周側に位置する部位もR面状)にされており、くり抜き作業でくり抜き対象部20bが加工層裏面方部22vから容易に破断され得る構造にされている。 In the present embodiment, as compared with the first embodiment, when the processing layer 22 is formed on the processing target single crystal substrate 20am in the second step, the back surface (bottom surface) side of the processing target single crystal substrate 20am is configured in the processing layer 22. In the processed layer back surface 22v, the distance r between the rotation center axis Cs of the rotating stage 11 and the irradiation central axis Cb of the laser condensing means 12 is gradually increased as the distance from the back surface 20v increases, and the distance r is gradually increased from the processing layer back surface 22v. This distance is constant on the irradiated surface 20u side (surface side) (see FIG. 17). Then, by gradually expanding in this way, the outer peripheral side of the back surface portion 22v of the processing layer is formed into an R-plane shape (cross-sectional arc shape) in which the diameter gradually increases as the distance from the back surface 20v of the single crystal substrate 20am to be processed increases. doing. As a result, the processed layer back surface portion 22v has a chamfered shape having a radius N (that is, the portion of the hollowing target portion 20b located on the inner peripheral side of the processed layer back surface portion 22v is also R-plane). The hollowed-out target portion 20b has a structure that can be easily broken from the back surface portion 22v of the processed layer.

本実施形態で用いる基板加工装置としては、例えば、第1実施形態で説明した基板加工装置10を用い、半径方向距離変更手段(図示せず)により距離rを徐々に広げる。この場合、回転ステージ11をこのように移動させる制御プログラムが基板加工装置の制御手段(CPUなど)に入力されていると、正確性や加工容易性を確保する上で好ましい。 As the substrate processing apparatus used in the present embodiment, for example, the substrate processing apparatus 10 described in the first embodiment is used, and the distance r is gradually increased by the radial distance changing means (not shown). In this case, it is preferable that the control program for moving the rotary stage 11 in this way is input to the control means (CPU or the like) of the substrate processing apparatus in order to ensure accuracy and ease of processing.

本実施形態では、加工層含有基板20cからくり抜き対象部20bをくり抜くことで、基板裏面側が半径NのR面状にされたくり抜き単結晶基板20dが容易に得られる。従って、くり抜き単結晶基板20dの面取り作業を、不要にすること或いは大幅に軽減させることができ、くり抜き単結晶基板20d(ウエハ)のハンドリングが容易になる。 In the present embodiment, by hollowing out the hollowed-out target portion 20b from the processed layer-containing substrate 20c, a hollowed-out single crystal substrate 20d having a radius N on the back surface side of the substrate can be easily obtained. Therefore, the chamfering work of the hollowed out single crystal substrate 20d can be made unnecessary or significantly reduced, and the handling of the hollowed out single crystal substrate 20d (wafer) becomes easy.

また、第2工程でレーザ光を照射する際、加工痕を1つ1つ繋げていくことでこのような加工層22が形成されるので、加工層22を形成する際にかかる時間を第1実施形態とさほど変わらない程度の時間に抑えることができる。 Further, when irradiating the laser beam in the second step, such a processed layer 22 is formed by connecting the processing marks one by one, so that the time required for forming the processed layer 22 is the first. The time can be suppressed to the same extent as that of the embodiment.

なお、加工層裏面方部22vでは、くり抜き対象部20bを良好にくり抜く観点で、裏面20vに近い位置ほどくり抜き対象部20b(ウエハ)の半径方向へ加工痕22cを繋げることが重要になっており、被照射面側(表面側)に近づくに従い、次第に基板厚み方向へ加工痕22cを繋げることが重要になっている。従って、裏面20vに近い位置ほど加工痕22cのラインピッチを狭くし、被照射面側(表面側)に近づくに従い次第にラインピッチを広げるなどの工夫をすることにより、くり抜き対象部20bを更に良好にくり抜くことが可能になる。 From the viewpoint of satisfactorily hollowing out the hollowed-out target portion 20b on the back surface portion 22v of the processed layer, it is important to connect the machining marks 22c in the radial direction of the hollowed-out target portion 20b (wafer) closer to the back surface 20v. As it approaches the irradiated surface side (surface side), it is important to gradually connect the processing marks 22c in the substrate thickness direction. Therefore, the line pitch of the processing mark 22c is narrowed toward the position closer to the back surface 20v, and the line pitch is gradually widened as it approaches the irradiated surface side (front surface side), so that the hollowed-out target portion 20b is further improved. It becomes possible to hollow out.

また、本実施形態では、加工層裏面方部22vの外周面をR面状に形成した例で説明したが、R面状に限らず湾曲凸面状としても、加工層含有基板20cからくり抜き対象部20bを容易にくり抜くことが可能である。 Further, in the present embodiment, the example in which the outer peripheral surface of the back surface portion 22v of the processed layer is formed in an R surface shape has been described, but the portion to be hollowed out from the processed layer containing substrate 20c is not limited to the R surface shape but also has a curved convex surface shape. It is possible to easily hollow out 20b.

また、加工層裏面方部22vではこのような形状にせずに、加工層22のうち加工対象単結晶基板20amの被照射面側(表面側)を構成する加工層表面方部を加工層裏面方部22vのような形状にすることで、基板表面側が半径NのR面状にされたくり抜き単結晶基板20dを得ることができる。 Further, the back surface portion 22v of the processed layer does not have such a shape, and the front surface portion of the processed layer forming the irradiated surface side (front surface side) of the single crystal substrate 20 am to be processed is formed on the back surface side of the processed layer. By forming the shape like the portion 22v, it is possible to obtain a hollow single crystal substrate 20d in which the surface side of the substrate has an R-plane shape with a radius N.

また、本実施形態に係る基板加工方法の説明では、加工対象単結晶基板20amが単結晶基板である例で説明したが、単結晶基板以外であっても、本実施形態に係る基板加工方法が適用可能である。 Further, in the description of the substrate processing method according to the present embodiment, the example in which the single crystal substrate 20 am to be processed is a single crystal substrate has been described, but the substrate processing method according to the present embodiment may be used even if the single crystal substrate is other than the single crystal substrate. Applicable.

本発明により、加工対象結晶基板からそれよりも小さい寸法の基板を得ることを可能にすることから、薄く切り出された基板は、例えば単結晶基板であって、Si基板(シリコン基板)であれば太陽電池に応用可能であり、また、GaN系半導体デバイスなどのサファイア基板などであれば、発光ダイオード、レーザダイオードなどに応用可能であり、SiCなどであればSiC系パワーデバイスなどに応用可能であり、透明エレクトロニクス分野、照明分野、ハイブリッド/電気自動車分野など幅広い分野において適用可能である。 Since the present invention makes it possible to obtain a substrate having a size smaller than that from the crystal substrate to be processed, the thinly cut substrate is, for example, a single crystal substrate and a Si substrate (silicon substrate). It can be applied to solar cells, sapphire substrates such as GaN-based semiconductor devices, light emitting diodes, laser diodes, etc., and SiC, etc., can be applied to SiC-based power devices, etc. It can be applied in a wide range of fields such as transparent electronics, lighting, and hybrid / electric vehicles.

10 基板加工装置
11 回転ステージ
12 レーザ集光手段
13 収差補正制御手段
15 集光レンズ
16 第1レンズ
18 第2レンズ
20a 加工対象結晶基板
20am 加工対象単結晶基板
20b くり抜き対象部
20c 加工層含有基板
20d くり抜き単結晶基板
20u 被照射面
20v 裏面(基板裏面)
22 加工層
22c 加工痕
22v 加工層裏面方部(加工層一方基板面方部)
B レーザ光
Bf 集光位置
Cb 照射中心軸
Cs 回転中心軸
E 外周部
EP 集光点
K 基板厚み方向長さ
L 距離
M 中央部
MP 集光点
Su ステージ面
r 距離
10 Substrate processing device 11 Rotating stage 12 Laser condensing means 13 Aberration correction control means 15 Condensing lens 16 1st lens 18 2nd lens 20a Processing target single crystal substrate 20am Processing target single crystal substrate 20b Hollow target part 20c Processing layer-containing substrate 20d Hollow single crystal substrate 20u Irradiated surface 20v Back surface (back surface of substrate)
22 Machining layer 22c Machining marks 22v Machining layer back surface (machining layer one side substrate)
B Laser light Bf Condensing position Cb Irradiation center axis Cs Rotation center axis E Outer circumference EP Condensing point K Substrate thickness direction Length L Distance M Central part MP Condensing point Su Stage surface r Distance

Claims (13)

レーザ光を集光するとともに収差補正が調整可能なレーザ集光手段を、加工対象結晶基板の被照射面上に非接触に配置する第1工程と、
前記レーザ集光手段により加工対象結晶基板内部にレーザ光を集光しつつ、レーザ光の集光位置を前記加工対象結晶基板のくり抜き対象部の周囲方向および厚み方向に変化させ、破断強度が低下した加工層を前記くり抜き対象部の外周側に形成することで加工層含有基板とする第2工程と、を備え、
前記第2工程では、加工対象結晶基板内部および少なくとも一方の加工対象結晶基板面近傍で、レーザ光の集光位置において生じる加工痕が、前記加工対象結晶基板の結晶方位に沿って伸張しかつ前記加工対象結晶基板の異なる結晶方位に沿って伸張しないように前記レーザ集光手段の収差補正を調整することを特徴とする基板加工方法。
The first step of arranging the laser condensing means capable of condensing the laser light and adjusting the aberration correction on the irradiated surface of the crystal substrate to be processed in a non-contact manner.
While concentrating the laser light inside the crystal substrate to be processed by the laser condensing means, the condensing position of the laser light is changed in the peripheral direction and the thickness direction of the hollowed-out target portion of the crystal substrate to be processed, and the breaking strength is lowered. A second step of forming a processed layer on the outer peripheral side of the hollowed-out target portion to form a processed layer-containing substrate is provided.
In the second step, the processing marks generated at the condensing position of the laser light inside the crystal substrate to be processed and near at least one surface of the crystal substrate to be processed extend along the crystal orientation of the crystal substrate to be processed and described above. A substrate processing method comprising adjusting the aberration correction of the laser condensing means so that the crystal substrate to be processed does not stretch along different crystal orientations.
前記第2工程では、前記加工対象結晶基板面近傍を前記被照射面とは反対側の面である基板裏面の近傍とし、
前記基板裏面から所定範囲内の基板厚み位置にレーザ光の焦点を合わせ、
前記レーザ集光手段を前記基板裏面から離れるように移動させつつレーザ光を照射して前記加工層を形成することを特徴とする請求項1に記載の基板加工方法。
In the second step, the vicinity of the surface of the crystal substrate to be processed is set to the vicinity of the back surface of the substrate, which is the surface opposite to the surface to be irradiated.
Focus the laser beam on the substrate thickness position within a predetermined range from the back surface of the substrate.
The substrate processing method according to claim 1, wherein the processing layer is formed by irradiating a laser beam while moving the laser condensing means away from the back surface of the substrate.
前記レーザ集光手段の収差補正を行う補正環により、前記基板裏面からの距離が大きい加工痕ほど加工痕長さが短くなるように前記補正環を調整することを特徴とする請求項2に記載の基板加工方法。 2. The method according to claim 2, wherein the correction ring for correcting the aberration of the laser condensing means adjusts the correction ring so that the processing mark length becomes shorter as the distance from the back surface of the substrate increases. Substrate processing method. 前記第2工程では、前記加工対象結晶基板面近傍を前記被照射面の近傍とし、
前記被照射面から所定範囲内の基板厚み位置にレーザ光の焦点を合わせ、
前記レーザ集光手段を前記被照射面から離れるように移動させつつレーザ光を照射して前記加工層を形成することを特徴とする請求項1に記載の基板加工方法。
In the second step, the vicinity of the crystal substrate surface to be processed is set to the vicinity of the irradiated surface.
Focus the laser beam on the substrate thickness position within a predetermined range from the irradiated surface.
The substrate processing method according to claim 1, wherein the processing layer is formed by irradiating a laser beam while moving the laser condensing means away from the irradiated surface.
前記レーザ集光手段の収差補正を行う補正環により、前記被照射面からの距離が大きい加工痕ほど加工痕長さが短くなるように前記補正環を調整することを特徴とする請求項4に記載の基板加工方法。 4. The fourth aspect of the present invention is characterized in that the correction ring for correcting the aberration of the laser condensing means adjusts the correction ring so that the processing mark length becomes shorter as the distance from the irradiated surface becomes larger. The substrate processing method described. 前記第2工程では、レーザ光の集光によって形成される前記加工痕の前記基板厚み方向の長さを10μm以下とすることを特徴とする請求項3または5に記載の基板加工方法。 The substrate processing method according to claim 3 or 5, wherein in the second step, the length of the processing marks formed by condensing laser light in the substrate thickness direction is 10 μm or less. 前記加工対象結晶基板として、前記被照射面の結晶方位が[100]である単結晶シリコンを用いることを特徴とする請求項1〜6の何れか1項に記載の基板加工方法。 The substrate processing method according to any one of claims 1 to 6, wherein a single crystal silicon having a crystal orientation of [100] on the irradiated surface is used as the crystal substrate to be processed. 前記第2工程では、前記加工層を短円筒状に形成することを特徴とする請求項1〜7の何れか1項に記載の基板加工方法。 The substrate processing method according to any one of claims 1 to 7, wherein in the second step, the processed layer is formed into a short cylindrical shape. 前記第2工程では、前記レーザ集光手段に入射するレーザ光の出力を一定にしておくことを特徴とする請求項1〜8の何れか1項に記載の基板加工方法。 The substrate processing method according to any one of claims 1 to 8, wherein in the second step, the output of the laser light incident on the laser condensing means is kept constant. 前記加工層のうち前記一方の加工対象単結晶基板面側を構成する加工層一方基板面方部の外周側は、前記一方の加工対象単結晶基板面から離れるにつれて径が徐々に大きくなる湾曲凸面状にされていることを特徴とする請求項1〜9の何れか1項に記載の基板加工方法。 Of the processed layers, the outer peripheral side of the one of the processed layers forming the surface side of the single crystal substrate to be processed is a curved convex surface whose diameter gradually increases as the distance from the one surface of the single crystal substrate to be processed increases. The substrate processing method according to any one of claims 1 to 9, wherein the substrate is formed in a shape. 載置された加工対象結晶基板を保持して回転する回転ステージと、
前記回転ステージ上に保持された前記加工対象結晶基板に向けてレーザ光を集光するとともにレーザ光の収差補正が調整可能なレーザ集光手段と、
前記回転ステージと前記レーザ集光手段との距離を変える照射軸方向距離変更手段と、前記距離に応じて前記収差補正の調整を制御する収差補正制御手段と、
を備え、
前記収差補正制御手段は、加工対象結晶基板内部および少なくとも一方の加工対象結晶基板面近傍で、レーザ光の集光位置において生じる加工痕が前記加工対象結晶基板の結晶方位に沿って伸張しかつ前記加工対象結晶基板の異なる結晶方位に沿って伸張しないように制御することを特徴とする基板加工装置。
A rotating stage that holds and rotates the placed crystal substrate to be processed,
A laser condensing means capable of condensing laser light toward the crystal substrate to be processed held on the rotating stage and adjusting the aberration correction of the laser light.
An irradiation axis direction distance changing means for changing the distance between the rotating stage and the laser condensing means, and an aberration correction controlling means for controlling the adjustment of the aberration correction according to the distance.
With
In the aberration correction control means, the processing marks generated at the condensing position of the laser beam extend along the crystal orientation of the processing target crystal substrate inside the processing target crystal substrate and in the vicinity of at least one processing target crystal substrate surface, and the processing marks are described. A substrate processing apparatus characterized in that it is controlled so as not to stretch along different crystal orientations of a crystal substrate to be processed.
レーザ光の収差補正を行う補正環としての機能を前記レーザ集光手段が備え、
前記収差補正制御手段は、少なくとも一方の加工対象結晶基板面からの距離が大きい加工痕ほど加工痕長さが短くなるように制御することを特徴とする請求項11に記載の基板加工装置。
The laser condensing means has a function as a correction ring for correcting aberrations of laser light.
The substrate processing apparatus according to claim 11, wherein the aberration correction control means controls so that the processing mark length becomes shorter as the distance from at least one processing target crystal substrate surface is larger.
前記回転ステージの回転中心軸と前記レーザ集光手段の照射中心軸との距離を変える半径方向距離変更手段を備えることを特徴とする請求項11または12に記載の基板加工装置。 The substrate processing apparatus according to claim 11 or 12, further comprising a radial distance changing means for changing the distance between the rotation center axis of the rotation stage and the irradiation center axis of the laser condensing means.
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