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DE-102022201285-B4 - METHOD FOR MACHINING A WORKPIECE

DE102022201285B4DE 102022201285 B4DE102022201285 B4DE 102022201285B4DE-102022201285-B4

Abstract

Method for machining a workpiece (11) comprising: a holding step (S10) for holding an end face (11a) of the workpiece (11) on a holding table (10) which has an area made of a transparent material, while a rear face (11b) of the workpiece (11) is exposed; and a machining groove training step (S30, S35) involving the training of a machining groove (13a) in the workpiece (11) by cutting the workpiece (11) held on the holding table (10) with a cutting blade (84a, 84b), where the processing groove training step (S30) exhibits: a first image acquisition step (S31) by taking an image of the machining groove (13a) on the back (11b) of the workpiece (11), a second image acquisition step (S36) with an image of the machining groove (13a) on the end face (11a) of the workpiece (10) being taken through the holding table (10), and a capture step (S32, S37) with a capture of whether a position of a first center line (13a 2 ) of the processing groove (13a), whose image was captured in the first image acquisition step (S31), and a position of a second center line (13b 2 ) of the processing groove (13a), whose image was captured in the second image acquisition step (S36), coincide in a predetermined plane or not, and If the position of the first center line (13a 2 ) and the position of the second center line (13b 2 ) in the predetermined plane do not match during the capture step (S32, S37), then the machining groove training step (S30) further includes a correction step (S33, S38) with a correction of a position of a center of the cutting blade (84a) to match the position of the first to align the midline (13a 2 ) and the position of the second midline (13b 2 ).

Inventors

  • Yoshimasa Kojima
  • Atsushi Kubo

Assignees

  • DISCO CORPORATION

Dates

Publication Date
20260513
Application Date
20220208
Priority Date
20210215

Claims (5)

  1. Method for machining a workpiece (11) comprising: a holding step (S10) for holding an end face (11a) of the workpiece (11) on a holding table (10) which has an area made of a transparent material, while a back face (11b) of the workpiece (11) is exposed; and a machining groove training step (S30, S35) comprising training a machining groove (13a) in the workpiece (11) by cutting the workpiece (11) held on the holding table (10) with a cutting blade (84a, 84b), wherein the machining groove training step (S30) comprises: a first image acquisition step (S31) with taking an image of the machining groove (13a) on the back (11b) of the workpiece (11), a second image acquisition step (S36) with taking an image of the machining groove (13a) on the front (11a) of the workpiece (10) through the holding table (10), and a detection step (S32, S37) with detecting whether a position of a first center line (13a 2 ) of the machining groove (13a), the image of which was taken in the first image acquisition step (S31), and a The position of a second center line (13b 2 ) of the processing groove (13a), whose image was captured in the second image acquisition step (S36), may or may not coincide in a predetermined plane, and if the position of the first center line (13a 2 ) and the position of the second center line (13b 2 ) do not coincide in the predetermined plane during the acquisition step (S32, S37), then the processing groove training step (S30) further includes a correction step (S33, S38) with a correction of a position of a center of the cutting blade (84a) to bring the position of the first center line (13a 2 ) and the position of the second center line (13b 2 ) into agreement.
  2. Method for machining a workpiece (11) according to Claim 1 , wherein the machining groove formation step (S30, S35) comprises: a first machining groove formation step (S30) with forming a first machining groove (13a) in the workpiece (11) with a first cutting blade (84a) having a first thickness (84a 1 ), wherein the first machining groove (13a) has a predetermined depth (23) to just before the end face (11a), and a second machining groove formation step (S35) with positioning a second cutting blade (84b) having a second thickness (84b 1 ), at the first machining groove and forming a second machining groove (13b) in the workpiece (11) along the first machining groove (13a), wherein the second machining groove (13b) extends to the end face (11a), thereby dividing the workpiece.
  3. Method for machining a workpiece (11) according to Claim 2 , where the second cutting blade (84b) has a narrower edge thickness than the first cutting blade (84a).
  4. Method for machining a workpiece (11) according to Claim 2 or 3 , wherein the first image acquisition step comprises taking an image of the first machining groove (13a) on the back (11b) with visible light using a first image acquisition unit (86a) arranged above the workpiece (11), the second image acquisition step comprises taking an image of the second machining groove (13b) on the front (11a) through the holding table (10) with visible light using a second image acquisition unit (54) arranged below the workpiece (11), and the detection step comprises detecting whether a position of a first center line (13a 2 ) of the first machining groove (13a) on the back (11b) and a position of a second center line (13b 2 ) of the second machining groove (13b) on the front (11a) coincide in the predetermined plane.
  5. Method for machining a workpiece (11) according to one of the Claims 2 until 4 , wherein the first image acquisition step comprises capturing an image of the first machining groove (13a) on the back side (11b) using infrared radiation through the holding table (10) using a third image acquisition unit (100) arranged under the workpiece (11), the second image acquisition step comprises capturing an image of the second machining groove (13b) on the front side (11a) using infrared radiation through the holding table (10) using the third image acquisition unit (100), and the detection step comprises detecting whether a position of a first center line (13a 2 ) of the first machining groove (13a) on the back side and a position of a second center line (13b 2 ) of the second machining groove (13b) on the front side (11a) coincide in the predetermined plane or not.

Description

BACKGROUND OF THE INVENTION AREA OF INVENTION The present invention relates to a method for machining a workpiece whose end face is held on a holding table which has an area made of a material that is transparent to visible light. DESCRIPTION OF THE RELATED STATE OF THE ART Electronic component chips are used in electronic devices such as mobile phones and personal computers. These chips are manufactured by dividing workpieces, such as silicon wafers, which have multiple components, such as integrated circuits (ICs), large-area integrated circuits (LSI), microelectromechanical systems (MEMS), or similar devices, embedded on their end faces. Specifically, the back side of such a workpiece is ground down by a grinding device until it is thinned to a predetermined thickness. The workpiece is then divided into individual component chips by a cutting device, which includes a cutting unit and a clamping table, along projected parting lines. Since components have become more diverse in recent years, a cutting method is known for cutting a workpiece along projected parting lines located on it, while one end face of the workpiece, where components are formed, is turned downwards and held under suction on a clamping table (see, for example, JP 2006- 140 341 A Normally, alignment marks are formed on the end face of such a workpiece, which are used to determine the positions of the projected parting lines. In a case where the end face of the workpiece is held against the clamping table with its back side facing upwards and under suction, it is necessary to position a camera unit capable of capturing workpiece images with infrared beams and capturing an image of the workpiece's end face through its back side with the camera unit positioned above the workpiece. A cutting device is known which has a clamping table that is transparent to visible light and a camera unit that is arranged below the clamping table for capturing workpiece images with visible light (see, for example, JP 2010- 87 141 A Even when the end face of a workpiece is held against the clamping table under suction, the cutting device allows the camera unit to capture an image of the workpiece's end face with visible light through the clamping table. Therefore, the cutting device can align the workpiece against the clamping table with a cutting unit based on the image captured by the camera unit, without the need for an infrared camera unit. In a case where the workpiece to be cut is made of a hard material or is relatively thick, a cutting method known as stepwise cutting was used. This method cuts the workpiece by repeatedly cutting along each of the projected parting lines formed on the workpiece's face. In accordance with the ordinary stepwise cutting method, the back of the workpiece is held under suction on a clamping table made of a porous ceramic or similar material, so that the workpiece's face is exposed. The workpiece is then aligned with a cutting unit using a camera unit based on an image of the workpiece's face taken by a visible-light camera positioned above the workpiece. The projected parting lines on the workpiece are essentially aligned parallel to the direction in which the workpiece and the cutting unit are to be fed relative to each other for machining. A first cutting blade then cuts the workpiece along the projected parting lines, creating initial machining grooves along the projected parting lines to a predetermined depth less than the workpiece thickness, meaning it does not divide the workpiece. A second cutting blade, thinner than the first, then cuts the bottoms of the initial machining grooves along the projected parting line to a depth sufficient to reach the back of the workpiece. Thus, in accordance with the step-cutting process, the workpiece is divided by the initial machining grooves, which are located closer to its end face, and the subsequent machining grooves, which are located closer to its back face. However, if the camera unit captures an image of the machining grooves from above the workpiece, the image will not include the subsequent machining grooves. ten, which are positioned closer to the back of the workpiece. Consequently, it is not possible to confirm from the captured image whether the center lines in the width of the first machining grooves and the center lines in the width of the second machining grooves are the same. The disclosure document JP 2010-087141A Disclosing a processing device for laser cutting of semiconductor wafers, and in particular an alignment imaging section of the processing device, the latter aims to position a workpiece, which has a layer that does not transmit light between the processing device and the object to be imaged, on the clamping table with its surface facing downwards and to perform an alignment without being affected by the structure of the workpiece. Further cutting devices and methods are described in the disclosed documents. JP 2018- 206 995 A and JP 2009- 289 786 A pr