JP2012059883A - Cutting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of uncutting by surely cutting a workpiece, when cutting the workpiece having a supporting member disposed on a backside.SOLUTION: A top surface position H of a dicing tape (supporting member) 6 stuck on the backside of a wafer (workpiece) 1 held by a holding table 20 is detected by noncontact type detecting means 30, and the dicing tape 6 is cut together with the wafer 1 by means of a cutting blade 13 located in a position in which a predetermined cutting depth value h is reduced from the top surface position H. The cutting depth of the cutting blade 13 is set surely below the backside of the wafer 1 to prevent the uncutting of the wafer 1.

Description

  The present invention relates to a cutting method suitable for use when a thin plate-like workpiece such as a semiconductor wafer is cut by a cutting blade and divided, and in particular, a support member such as a dicing tape on the back surface of the workpiece. The present invention relates to a cutting method in the case where is provided.

  In the manufacturing process of a semiconductor device, first, circuit elements such as IC, LSI, LED, etc. are formed in a large number of rectangular areas defined by lattice-shaped division lines formed on the surface of a wafer made of silicon, gallium arsenide, sapphire, or the like. Is formed. The wafer on which the circuit elements are formed is cut along a predetermined division line by a cutting device, divided into individual chips, and diced. The separated chips are packaged with resin or ceramic and manufactured into various devices.

  For example, a cutting apparatus known from Patent Document 1 is used for dividing the wafer. The cutting apparatus includes a holding table for holding a workpiece such as a wafer, a cutting blade in which abrasive grains such as diamond and CBN (Cubic Boron Nitride) for cutting the workpiece are hardened with a resin or metal, and a cutting blade. And a rotating spindle. When cutting a workpiece with such a cutting device, a support member is previously attached to the back surface of the wafer by sticking in order to facilitate handling of the workpiece before division and the chip after division. Is done. Examples of the support member include a sheet-like pressure-sensitive adhesive tape called a dicing tape, a substrate made of a relatively easy-to-cut member such as a glass plate, a carbon plate, and a silicon wafer. Then, for example, cutting is performed by relatively moving the workpiece and the cutting blade in the direction of the division line while cutting the cutting blade rotated at a high speed of about 30000 rpm (revolution per minute) to the support member. ing.

  On the other hand, in recent years, a stacked package in which a plurality of semiconductor devices are stacked is used in order to achieve high density and miniaturization of devices. In a semiconductor device constituting such a stacked package, a die bonding adhesive film called DAF (Die Attach Film) is pasted on the back surface, and the stacked state of the semiconductor devices is held by this adhesive film.

  Regarding this adhesive film, Patent Document 2 discloses a method of breaking an adhesive film adhered to the back surface of a workpiece. In this breaking method, the workpiece is cut while cutting the cutting blade halfway through the thickness of the adhesive film, and then the dicing tape (adhesive tape) is expanded to break the adhesive film along the chip. Usually, the amount of cutting when a cutting blade is cut into a support member disposed on the back surface of a workpiece such as an adhesive tape, an adhesive film, or a substrate is set based on the upper surface position of the holding table ( (See Patent Document 3).

JP 2006-231474 A JP 2007-294651 A JP-A-61-71967

  However, in the method in which the cutting amount of the cutting blade into the support member is set based on the position of the upper surface of the holding table, the cutting blade reaches a part of the workpiece to the support member due to the variation in the thickness of the support member. Is not cut, and there is a problem that uncut occurs that the workpiece is not completely cut in the thickness direction. For example, when the adhesive film is broken by the method disclosed in Patent Document 2, there arises a problem that the adhesive film is not broken unless a cutting blade is cut into the adhesive film.

  The present invention has been made in view of the above circumstances, and its main technical problem is that when cutting a workpiece having a support member disposed on the back surface, the workpiece is reliably cut and uncut. The object is to provide a cutting method capable of preventing the occurrence.

  The cutting method of the present invention is a cutting method in which a workpiece having a support member disposed on the back surface is cut with a cutting blade, the holding step of holding the support member side of the workpiece with a holding table, An upper surface position detecting step for detecting the upper surface position of the support member disposed on the workpiece held by the holding table by a non-contact type detecting means, and the upper surface position of the support member detected by the upper surface position detecting step. A positioning step of positioning the tip of the cutting blade at a position obtained by subtracting a predetermined cutting depth value from the position, and after performing the positioning step, the cutting blade and the holding table are moved relative to each other, thereby A cutting step of cutting the workpiece together with the support member while cutting the support member at the predetermined cutting depth.

  According to the present invention, since the cutting amount of the cutting blade into the support member is set based on the upper surface position of the support member, the cutting amount can be set regardless of the thickness of the support member. Therefore, even if the thickness of the support member varies, the cutting blade can be surely cut into the support member with a constant cut amount, and uncut of the workpiece is prevented.

  The workpiece to be referred to in the present invention is not particularly limited. For example, a semiconductor wafer made of silicon, gallium arsenide, or silicon carbide, a semiconductor product package, a ceramic, glass, a sapphire inorganic substrate, a liquid crystal display, and the like. Examples include various electronic components such as an LCD driver that controls and drives the apparatus, and various processing materials that require micron-order processing position accuracy.

  According to the present invention, in a method of cutting a workpiece having a support member disposed on the back surface, a cutting method capable of reliably cutting the workpiece and preventing the occurrence of uncut is provided. There is an effect.

It is a perspective view which shows the state by which the semiconductor wafer diced by the cutting method which concerns on one Embodiment of this invention is supported by the flame | frame via the dicing tape. It is a perspective view which shows the state which cuts a semiconductor wafer with the cutting method which concerns on one Embodiment. It is a side view which shows the upper surface position detection process of the cutting method which concerns on one Embodiment. It is a side view which shows an upper surface position detection process in detail. It is a side view which shows the positioning process of the cutting method which concerns on one Embodiment. It is a side view which shows a positioning process in detail. It is a side view which shows the cutting process which concerns on one Embodiment. It is a side view which shows a cutting process in detail. It is a perspective view which shows the other form of the supporting member stuck on the back surface of a wafer (a supporting member is DAF). It is a perspective view which shows the other form of a to-be-processed object and a supporting member (a to-be-processed object is quartz glass, a supporting member is a substrate).

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
(1) Semiconductor wafer The code | symbol 1 of FIG. 1 has shown the disk-shaped semiconductor wafer (to-be-processed object, hereafter abbreviated as a wafer) diced by the cutting method of one Embodiment. On the surface of the wafer 1, a plurality of division lines 2 orthogonal to each other are formed in a lattice shape, and a rectangular device region 3 partitioned by the division lines 2 is formed. On the surface of each device region 3, a circuit element (not shown) made of IC, LSI, LED or the like is formed.

  The wafer 1 is held on a disk-like holding table 20 as shown in FIGS. 2 and 5 in a state where it is integrally supported inside the frame 5 via a dicing tape (supporting member) 6. Then, the dividing line 2 is cut by the cutting blade 13 of the cutting means 10, and dicing is performed in which the device region 3 is divided as a device (semiconductor chip). One surface of the dicing tape 6 is an adhesive surface, and the back surface of the frame 5 and the wafer 1 is attached to the adhesive surface. The wafer 1 is handled by supporting the frame 5.

(2) Cutting means The cutting means 10 shown in FIG. 2 is provided in a cutting device (not shown), and includes a cylindrical spindle housing 11, a spindle shaft 12 rotatably supported in the spindle housing, and the spindle shaft 12 The cutting blade 13 is fixed to the tip of the cutting blade 13. A motor (not shown) that rotates the spindle shaft 12 is accommodated in the spindle housing 11. The cutting means 10 has a spindle shaft 12 installed in parallel to the Y direction, can be moved in the vertical direction (Z direction) by a vertical movement means (not shown), and the axial direction (Y direction) of the spindle shaft 12 by an index feeding means. ) Can be moved.

  The wafer 1 supported by the frame 5 via the dicing tape 6 is concentric with the surface being the processing surface exposed upward on a holding table 20 disposed horizontally below the cutting means 10. It is mounted and held. That is, the wafer 1 is held on the holding table 20 with the back surface facing the holding table 20 via the dicing tape 6. The holding table 20 is rotated by rotating a rotating shaft 21 fixed in the center of the lower surface and extending in the vertical direction (Z direction), whereby the wafer 1 is rotated. The holding table 20 can be moved in the X direction by a processing feed means (not shown). Although not shown in FIG. 2, a clamp 22 that holds the frame 5 is disposed around the holding table 20 as shown in FIGS. 3 and 5.

  In the cutting of the wafer 1 by the cutting means 10, that is, the cutting of the division line 2, first, the wafer 1 is held on the holding table 20 via the dicing tape 6 and the frame 5 is held by the clamp 22 as shown in FIG. To do. Then, the holding table 20 is rotated to rotate the wafer 1 so that the division target line 2 to be cut is parallel to the moving direction of the holding table 20 (X direction in FIG. 2).

  Next, while moving the holding table 20 in the X2 direction in FIG. 2, the cutting edge 13 at the tip (lower end) of the cutting blade 13 rotating in the arrow C direction is cut from the X2 side end of the wafer 1, and the cutting blade 13 is moved. Processing feed is performed to move relatively in the X1 direction. Thereby, the cutting blade 13 cuts into the wafer 1, and the division | segmentation scheduled line 2 is cut and cut | disconnected. The machining feed direction is a fixed direction according to the rotation direction of the cutting blade 13, and in this case, is the X1 direction. Moreover, selection of the division | segmentation scheduled line 2 to cut | disconnect is made | formed by the index feed which moves the cutting means 10 to a Y direction.

(3) Cutting Method Next, a procedure for cutting the wafer 1 by the cutting method of the embodiment using the cutting means 10 will be described.

(3-1) Holding Step As shown in FIG. 3, the wafer 1 is placed and held concentrically on the holding table 20 via the dicing tape 6, and the frame 5 is held by the clamp 22. The frame 5 held by the clamp 22 is lowered below the upper surface of the holding table 20. The upper surface of the clamp 22 is slightly lower than the upper surface of the holding table 20, so that the cutting blade 13 does not interfere with the clamp 22. The outer diameter of the wafer 1 is smaller than the outer diameter of the holding table 20. Therefore, the dicing tape 6 is exposed in an annular shape on the outer peripheral portion of the upper surface of the holding table 20. This portion is defined as an annular exposed portion 6 a of the dicing tape 6.

(3-2) Upper surface position detection step As shown in FIG. 3, the non-contact detection means 30 is positioned above the annular exposed portion 6 a of the dicing tape 6. The non-contact detection means 30 detects the upper surface position (referred to as the height position of the upper surface) H of the annular exposed portion 6a shown in FIG. The non-contact type detection means 30 may be anything as long as it can detect the height position of the upper surface of the dicing tape 6 in a non-contact manner. For example, the back pressure type disclosed in Japanese Patent Application Laid-Open No. 2001-298003. A height position detector is preferably used.

(3-3) Positioning Step The cutting blade 13 positioned relatively above the periphery of the holding table 20 is lowered as indicated by an arrow A in FIG. 5, and is detected in the upper surface position detecting step as shown in FIG. The tip (lower end) of the cutting blade 13 is positioned at a position obtained by subtracting a predetermined cutting depth value h from the upper surface position H of the dicing tape 6. The cutting depth value h here is a depth up to the middle of the thickness of the dicing tape 6, does not reach the upper surface of the holding table 20, and can be cut through the wafer 1 sufficiently. Say quantity.

(3-4) Cutting Step With the height position of the cutting blade 13 held at the position positioned in the positioning step, the holding table 20 is moved while rotating the cutting blade 13 in the C direction, so that FIG. As shown, the cutting blade 13 is relatively fed in the direction of the arrow X1 to cut the tip of the cutting blade 13 along the planned division line 2. As a result, as shown in FIG. 8, the wafer 1 passes through the division line 2 in the thickness direction and is completely cut, and the dicing tape 6 is cut from the upper surface by the amount of the cut depth value h. . Such a cutting operation of the planned division line 2 is performed on all the planned division lines 2.

  Thus, the wafer 1 is diced into individual device regions 3 (semiconductor chips). When the wafer 1 is divided on the dicing tape 6, each semiconductor chip remains adhered on the dicing tape 6, and thereafter, each semiconductor chip is picked up from the dicing tape 6 in a pickup process.

  In the cutting method of the above embodiment, the cutting amount h of the cutting blade 13 into the wafer 1 is set with the upper surface position H of the dicing tape 6 as a reference. For this reason, the cutting amount h of the cutting blade 13 can be set irrespective of the thickness of the dicing tape 6. Therefore, even if the thickness of the dicing tape 6 varies, the cutting blade 13 can be reliably cut into the dicing tape 6 with a constant cut amount, and as a result, uncutting of the wafer 1 can be prevented.

(4) Other Support Member In the above embodiment, the dicing tape 6 is the support member for the wafer 1, but the support member referred to in the present invention is not limited to this. For example, as shown in FIG. A DAF (adhesive film) 7 for die bonding that is bonded to the back surface is mentioned. A dicing tape 6 is attached to the back surface of the DAF 7, and the wafer 1 is handled through the frame 5 as in the above embodiment. In this case, as described in Patent Document 2, the tip of the cutting blade 13 penetrating the wafer 1 is cut into the DAF 7 to a predetermined depth, and the dicing tape 6 is expanded so that the DAF 7 is cut into semiconductor chips. It is broken and divided in a state where it is adhered to.

  Further, in FIG. 10, a rectangular plate-shaped quartz glass 8 is a workpiece, and a substrate 9 is attached to the back surface of the quartz glass 8 as a support member. In this case, the quartz glass 8 is cut and divided by cutting the cutting blade by cutting a predetermined depth of the substrate 9 from the surface side of the quartz glass 8.

1 ... Semiconductor wafer (workpiece)
2 ... Divided line 6 ... Dicing tape (supporting member)
13 ... Cutting blade 20 ... Holding table 30 ... Non-contact detection means H ... Upper surface position h ... Cutting amount (cutting depth value)

Claims (1)

A cutting method of cutting a workpiece having a support member on the back surface with a cutting blade,
A holding step of holding the support member side of the workpiece with a holding table;
A top surface position detecting step of detecting a top surface position of the support member disposed on the workpiece held by the holding table by a non-contact type detecting means;
A positioning step of positioning the tip of the cutting blade at a position obtained by subtracting a predetermined cutting depth value from the upper surface position of the support member detected in the upper surface position detection step;
After carrying out the positioning step, the cutting blade and the holding table are moved relative to each other so that the cutting blade is cut into the support member at the predetermined cutting depth, and the workpiece is supported on the support member. Cutting process to cut with,
A cutting method comprising:

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