JP6509614B2 - Wafer division method - Google Patents

Description

  The present invention relates to a method of dividing a wafer in which both a wafer and a DAF tape stuck to the wafer can be divided along a planned dividing line.

  In the semiconductor device manufacturing process, formation of devices such as IC and LSI is performed in a plurality of areas divided by dividing planned lines called streets arranged on the surface of a wafer having a substantially disk shape. Then, by cutting the wafer along the streets, the wafer is divided for each area where devices are formed, and individual device chips are manufactured.

  As a dividing method of dividing such a wafer or the like along a planned dividing line, dicing processing or laser processing is performed. In dicing processing, since cutting is performed by a high-speed rotating cutting blade, chips are likely to be chipped due to the crushing force of the cutting blade, and there is a problem that the bending strength of the divided chips is lowered. Further, in laser processing, the range along the planned dividing line becomes high temperature to cause damage, which also causes a problem that the bending strength of the divided chip becomes low.

  Here, Patent Document 1 discloses a processing method of dividing a wafer into individual chips using plasma etching. In this processing method, plasma etching is performed from the front surface to the back surface of the wafer at positions along planned dividing lines, so the problems of dicing processing and laser processing described above do not occur, and a decrease in bending strength is suppressed. Can.

  In the individual chips thus divided, a DAF (Die Attach Film) tape is stuck on the back surface as an adhesive film for lamination (see Patent Document 2). In patent document 2, after sticking a DAF tape on the back surface of the wafer divided | segmented into each chip | tip, the DAF tape is cut | disconnected along a dividing line by laser ablation.

JP, 2006-114825, A Patent No. 4791843 gazette

  However, when the DAF tape is cut by laser ablation, the effect of heat causes the DAF tape to expand and the dividing line of the DAF tape does not become straight. Therefore, there is a problem that it becomes difficult to cut the DAF tape along the outer edge of the chip which is the dividing position of the wafer.

  The present invention has been made in view of these points, and it is an object of the present invention to provide a wafer dividing method capable of easily dividing a DAF tape attached to a wafer while improving the bending strength. I assume.

In the wafer dividing method of the present invention, a wiring layer is provided on the front surface, and division is made by a plurality of dividing lines to form a device, the back surface of the wafer is ground and thinned to a predetermined thickness, A process of dividing a wafer to be divided together with a DAF tape along a planned dividing line, wherein a DAF tape affixing step of affixing the DAF tape to a back surface of the wafer thinned to a predetermined thickness; Step of attaching a protective tape to the surface of the DAF tape attached in the second step, a step of forming a resist film on the surface of the wafer , a step of forming a resist film, and holding the chuck table holds the wafer through the protective tape. process and the tip along the surface of the wafer held on the chuck table the dividing lines are not cut the cutting blade pointed at an acute angle in the holding step, A V-groove forming step of forming a V-groove Eha surface, after of the V-groove forming step, plasma etched from the surface side of the wafer is allowed to proceed toward a V groove on the back, the wafer to the tip of the V-groove reaches the back surface The plasma etching step of plasma etching, the resist film removing step of removing the resist film on the wafer surface, and the dividing step of dividing the DAF tape starting from the tip of the V groove after the plasma etching step I assume.

  According to this configuration, the V-shaped groove is formed on the wafer surface by cutting the cutting blade, and plasma etching is performed to advance the V-shaped groove toward the back surface, so that the side of the chip formed by dividing the wafer is cleaned. And can improve the bending strength. In addition, the tip of the V groove progresses to reach the back surface of the wafer by plasma etching, and the tip of the V groove becomes the starting point of the division of the DAF tape, so the division of the DAF tape can be easily performed at a predetermined position.

  According to the present invention, it is possible to easily divide the DAF tape attached to the wafer while improving the bending strength.

It is a perspective view showing an example of a wafer. It is a figure which shows an example of the DAF tape sticking process which concerns on embodiment. It is a figure which shows an example of the protective tape sticking process which concerns on embodiment. It is a figure which shows an example of the resist film formation process which concerns on embodiment. It is a figure which shows an example of the holding | maintenance process which concerns on embodiment. It is a figure which shows an example of the V groove formation process which concerns on embodiment. It is a figure which shows an example of the plasma etching process concerning embodiment. It is a figure which shows an example of the resist film removal process concerning embodiment. It is a figure which shows an example of the division | segmentation process which concerns on embodiment. It is a figure which shows the back of the protective tape sticking process of the wafer which concerns on a modification. It is a figure which shows an example of the V groove formation process which concerns on a modification. It is a figure which shows an example of the plasma etching process concerning a modification.

  Hereinafter, a method of dividing a wafer according to the present embodiment will be described with reference to the attached drawings. First, the wafer will be described with reference to FIG. FIG. 1 is a perspective view showing an example of a wafer.

  As shown in FIG. 1, the wafer 1 is formed in a substantially disc shape. The surface (upper surface) 1a of the wafer 1 is divided into a plurality of areas by a plurality of crossing planned dividing lines 2, and devices 3 are formed in each of the divided areas. The device 3 has a wiring layer (not shown) on the surface 1 a of the wafer 1. In the present embodiment, the wafer 1 is a semiconductor wafer in which a device such as an IC or an LSI is formed on a semiconductor substrate such as silicon or gallium arsenide.

  Subsequently, the flow of the wafer dividing method according to the present embodiment will be described with reference to FIGS. 2 to 9. The wafer dividing method according to the present embodiment includes a DAF tape attaching step, a protective tape attaching step, a resist film forming step, a holding step, a V groove forming step, a plasma etching step, a resist film removing step, and a dividing step. including. 2 to 9 are explanatory views of steps in the wafer dividing method. In addition, these processes are only an example to the last, and are not limited to this structure.

  First, the DAF tape sticking process shown in FIG. 2 is performed. Before the DAF tape attaching step, the back surface 1b of the wafer 1 is ground and thinned to a predetermined finished thickness by contact with the rotating grinding wheel. In the DAF tape attaching step, the DAF tape 5 is attached as an adhesive film for die bonding to the back surface 1 b which is the lower surface in FIG. 2 of the wafer 1. The adhesion of the DAF tape 5 may be performed by rolling the adhesion roller of the tape mounter to press the DAF tape 5 against the wafer 1 or may be performed manually by an operator.

  After the DAF tape attaching process is performed, as shown in FIG. 3, a protective tape attaching process is performed. In the protective tape bonding step, the wafer 1 is placed inside the frame 7 with the surface 5 a of the DAF tape 5 facing upward. Thereafter, the surface 5a side of the DAF tape 5 and the upper surface of the frame 7 are integrally adhered by the protective tape 8, and the wafer 1 is mounted on the frame 7 through the DAF tape 5 and the protective tape 8. As the protective tape 8, a resin film having stretchability is used.

  After the protective tape attaching step is performed, as shown in FIG. 4, a resist film forming step is performed. The resist film forming step is performed before the V groove forming step described later. In the resist film forming step, the entire region of the surface 1 a of the wafer 1 is covered with a resist film 9. For example, while rotating a spinner table (not shown) holding the wafer 1 at high speed, a resist film agent is applied to the surface 1 a of the wafer 1 from a nozzle or the like (not shown). Thereby, a thin resist film 9 is formed on the surface 1 a of the wafer 1 by a so-called spin coating method.

  After the resist film formation step is performed, as shown in FIG. 5, the holding step is performed. In the holding step, the wafer 1 is held on the chuck table 11 via the protective tape 8 via a transport means (not shown). A holding surface 11a connected to a suction source (not shown) is formed on the chuck table 11, and the wafer 1 is held by suction via the protective tape 8 by the negative pressure generated on the holding surface 11a.

  After the holding process is performed, as shown in FIG. 6, the V-groove forming process is performed. In the V-groove forming step, the cutting blade 13 of the dicing apparatus is cut into the resist film 9 on the front surface 1 a side of the wafer 1 held on the chuck table 11. As a result, the V-grooves 15 are formed in a lattice shape along the planned dividing lines 2 on the surface 1 a of the wafer 1 by cutting so as to penetrate the resist film 9. The tip of the cutting blade 13 is formed in a sharp V-shape. Therefore, the front end side (bottom side) of the V groove 15 also has a tapered shape in the direction from the front surface 1a to the rear surface 1b of the wafer 1 and is formed at an acute angle. The depth of the V groove 15 is set such that substantially all of the tapered portion is on the back surface 1b side of the front surface 1a of the wafer 1, and the wafer 1 is covered with the resist film 9 on the inner bottom side of the V groove 15. It is exposed without being done.

  After the V groove formation process is performed, as shown in FIG. 7A, a plasma etching process is performed. In the plasma etching step, first, the wafer 1 mounted on the frame 7 is loaded into a chamber of a plasma etching apparatus (not shown). Then, the etching gas is ejected into the chamber and a high frequency voltage is applied to plasmify the etching gas. Then, a portion of the surface 1a of the wafer 1 not coated with the resist film 9, that is, only the inside of the V groove 15 of the planned dividing line 2 is plasma etched due to the etching effect of plasma. Thus, plasma etching is performed from the front surface 1a side of the wafer 1 and the V groove 15 is advanced toward the back surface 1b. Then, plasma etching is performed until the front end of the V groove 15 reaches the back surface 1 b of the wafer 1, and the V groove 15 penetrates the wafer 1 vertically and horizontally at the dividing line 2, and individual chips provided with the devices 3. It is divided into seventeen. In plasma etching, anisotropic etching is possible, and the side surface of each chip 17 can be formed substantially vertically except for the tip side of the V groove 15.

  As shown in FIGS. 7B and 7C, which are enlarged views of part A of FIG. 7A, the V groove 15 reaches the back surface 1b of the wafer 1 with its tip end side pointed. A protruding protrusion 19 is formed. Thus, the wafer 1 is plasma etched maintaining the shape of the V-groove 15, but the DAF tape 5 is not plasma etched. The protrusion 19 forms a tip end side of a V-shaped groove 15 whose upper surface is tapered to be tapered, and the lower surface is adhered to the DAF tape 5. There are cases where the tips of the two projections 19 forming the V-shaped groove 15 are slightly separated (see FIG. 7B) and in the case where the tips of the two projections 19 are continuous and the thickness is extremely thin (see FIG. 7C). Even in such a case, in the dividing step, the tip 17 is first divided, and the tip of the protrusion 19 becomes the dividing start point of the DAF tape 5.

After the plasma etching process is performed, as shown in FIG. 8, a resist film removing process is performed. The resist film removing step is performed between the plasma etching step and the dividing step described later. In the resist film removing step, wet etching is performed, and the resist film 9 on the surface 1 a of the wafer 1 is removed by a chemical solution. In the resist film removing step, the above-mentioned plasma etching apparatus or ashing apparatus (not shown) may be used. In this case, the resist film 9 is oxidized and ashed and removed by injecting an O ₂ gas or the like into the chamber and applying a high frequency voltage to plasmify the O ₂ gas.

  After the resist film removing step is performed, as shown in FIG. 9, the dividing step is performed. In the dividing step, the frame 7 is placed on the annular table 21 of the tape expansion device (not shown), and the frame 7 is held on the annular table 21 by the clamp unit 22. The outer diameter of the extension drum 23 is smaller than the inner diameter of the frame 7, and the inner diameter of the extension drum 23 is larger than the outer diameter of the wafer 1. Therefore, the upper end portion of the expansion drum 23 is in contact with the protective tape 8 between the wafer 1 and the frame 7.

  From this state, the expansion drum 23 is raised relative to the annular table 21 by lowering the frame 7 together with the annular table 21 and the protective tape 8 is expanded in the radial direction. When tension is applied to the DAF tape 5 by the expansion of the protective tape 8, the DAF tape 5 is broken and divided along the planned dividing line 2. At this time, since the V groove 15 is formed between the adjacent chips 17, tension on the DAF tape 5 acts intensively between the tips of the two projections 19 (see FIG. 7B) forming the V groove 15. Do. Therefore, the fracture division of the DAF tape 5 is performed starting from the tip of the V groove 15. When the DAF tape 5 is divided, the distance between the individual chips 17 is increased. In this state, a small piece of DAF tape 5 broken at the position of the dividing line 2 is attached to each of the plurality of chips 17.

  As described above, the chips 17 disposed at intervals on the protective tape 8 are adsorbed by the pickup collet (not shown) and peeled off from the protective tape 8. The chip 17 to which the DAF tape 5 is attached is bonded by pressure bonding the DAF tape 5 side to a die bonding frame (not shown).

  As described above, according to the dividing method according to the present embodiment, the side surface of the chip 17 can be finely formed by the progress of the V groove 15 by plasma etching, and the bending strength of each chip 17 can be enhanced. In addition, since the V groove 15 cut and formed by the cutting blade 13 is used as the starting point of the division of the wafer 1 by plasma etching, the division positions of both the wafer 1 and the DAF tape 5 can be made linear accurately.

  Here, for example, in a configuration in which the width of the groove between the chips 17 becomes uniform and reaches the back surface 1b, the DAF tape 5 extends in the range of the width of the groove when the protective tape 8 is expanded. The division position of 5 is not constant with respect to the outer edge of the chip 17. On the other hand, in the present embodiment, since the tip of the V groove 15 reaches the back surface 1b of the wafer 1 and the lower surface of the protrusion 19 is adhered to the DAF tape 5, the V groove is expanded when the protective tape 8 is expanded. The DAF tape 5 is broken and divided from the tip of 15. As a result, the starting point of the division of the DAF tape 5 can be set as a very thin linear shape at a fixed position as the tip of the V groove 15, and the DAF tape 5 can be easily divided with high accuracy.

  The present invention is not limited to the above embodiment, and can be implemented with various modifications. In the above embodiment, the size, shape, direction, and the like shown in the attached drawings are not limited to the above, and can be appropriately changed within the range in which the effects of the present invention are exhibited. In addition, without departing from the scope of the object of the present invention, it is possible to appropriately change and implement.

  For example, as shown in FIG. 10, when dividing the wafer 1 whose surface 1a is coated with the oxide film 1c, the dividing method can be made by omitting the resist film forming step and the resist film removing step of the above embodiment. . FIG. 10 is a view showing the wafer after the protective tape attaching step according to the modified example. FIG. 11 is a view showing an example of a V-groove forming step according to a modification, and FIG. 12 is a view showing an example of a plasma etching step according to the modification.

In the present modification, the oxide film 1c is made of a SiO ₂ film or the like, and the surface 1a of the wafer 1 can be prevented from being plasma-etched in the region covered with the oxide film 1c. Therefore, in the modification, as shown in FIG. 11, the oxide film 1c is cut by the cutting blade 13, and the V groove 15 is formed on the surface 1a of the wafer 1 along the planned dividing line 2 as in the above embodiment. Then, as shown in FIG. 12, the front end of the V-shaped groove 15 reaches the back surface 1 b of the wafer 1 by performing plasma etching in the same manner as the above embodiment. Thus, after the V groove 15 is formed, the dividing process can be performed in the same manner as the above embodiment, and the DAF tape 5 can be easily divided. Further, even if the nitride film is made of Si ₃ N ₄ film or the like in addition to the oxide film 1 c, the cutting blade 13 is similarly cut into the nitride film to form the V groove 15 on the surface 1 a of the wafer 1 You may carry out the formation process.

  Further, in the above embodiment, each of the above steps may be performed by separate devices or may be performed by the same device.

  As described above, the present invention is useful for a dividing method of dividing a wafer with a DAF tape along a planned dividing line.

Reference Signs List 1 wafer 1 a front surface 1 b back surface 2 division planned line 3 device 5 DAF tape 8 protective tape 9 resist film 11 chuck table 13 cutting blade 15 V groove 17 chip

Claims (1)

The back side of the wafer which has a wiring layer on the surface and is divided by a plurality of dividing lines to form a device is ground and thinned to a predetermined thickness, a DAF tape is attached to the back surface, and along the dividing lines A wafer dividing method for dividing with the DAF tape, comprising:
DAF tape sticking step of sticking a DAF tape on the back surface of a wafer thinned to a predetermined thickness;
A protective tape sticking step of sticking a protective tape on the surface of the DAF tape stuck in the DAF tape sticking step;
A resist film forming step of forming a resist film on the wafer surface;
A holding step in which the chuck table holds the wafer via the protective tape;
A V-groove forming step of forming a V-shaped groove on the wafer surface by cutting a cutting blade whose acute end is sharpened along the planned dividing line from the surface side of the wafer held by the chuck table in the holding step;
After the V-groove forming step, plasma etching is performed from the front surface side of the wafer to advance the V-groove toward the back surface, and plasma etching the wafer until the front end of the V-groove reaches the back surface;
A resist film removing step of removing the resist film on the wafer surface;
A dividing step of dividing the DAF tape starting from the tip of the V groove after the plasma etching step;
Method of dividing wafer.

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