JP2013222935A - Method for grinding wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for grinding a wafer capable of reducing risk that quality degradation or breakage such as surface burning occurs in a wafer.SOLUTION: A method for grinding a wafer comprises the steps of: holding a surface side of the wafer by a chuck table; and grinding a rear surface of the wafer held by the chuck table by grinding means having a grinding wheel. The grinding step is performed while an auxiliary liquid for improving sticking of the grinding wheel to the wafer is being supplied to the wafer.

Description

  The present invention relates to a wafer grinding method for grinding a back surface of a wafer having a device region having a plurality of devices formed on the surface and an outer peripheral surplus region surrounding the device region.

  A wafer such as a semiconductor wafer having a plurality of semiconductor devices such as IC and LSI formed on the front surface is ground to a predetermined thickness by a grinding machine and then cut into individual devices by a cutting machine. Is done. The divided devices are widely used in various electric devices such as mobile phones and personal computers.

  In order to protect the device formed on the surface, a surface protective tape as disclosed in JP-A-2000-104026 is applied in advance to the surface of the wafer when grinding with a grinding machine, and the surface is finished when grinding is finished. The protective tape is peeled off from the surface of the wafer.

  In general, when grinding a wafer, in order to shorten the processing time and flatten the wafer with high precision, the wafer is ground with a coarse grinding wheel with coarse abrasive grains, and then the wafer is ground with a finish grinding wheel with fine abrasive grains. The thickness is reduced to a predetermined thickness.

JP 2010-149222 A JP 2000-104026 A

  Various wafers such as a silicon wafer and a sapphire wafer are mirror-finished on both front and back surfaces, and then a semiconductor layer is formed on the surface. Therefore, when the back surface of a wafer having a semiconductor layer on the surface is ground, since the back surface is mirror-finished, a so-called biting failure may occur in which the grinding wheel is not cut into the wafer.

  Similarly, when a wafer once ground with a finish grinding wheel is ground again with a finish grinding wheel, a biting failure may occur in the same manner. When a biting failure occurs, there are problems that the wafer is burnt, the pressing force increases with grinding feed, the wafer is damaged, and the quality of the device is degraded.

  The present invention has been made in view of such points, and the object of the present invention is to provide a method for grinding a wafer that can reduce the risk of quality degradation and damage such as surface burning on the wafer. is there.

  According to a first aspect of the present invention, there is provided a method for grinding a wafer, wherein a holding step for holding the front surface side of the wafer with a chuck table and a back surface of the wafer held by the chuck table are ground by a grinding means having a grinding wheel. And a grinding step, wherein the grinding step is performed while a biting auxiliary liquid that improves biting of the grinding wheel against the wafer is supplied to the wafer.

  According to a second aspect of the present invention, there is provided a method for grinding a wafer, wherein a holding step for holding the front side of the wafer with a chuck table and a biting auxiliary liquid for improving biting of the grinding wheel against the wafer are held by the chuck table. The grinding wheel approaches the wafer while moving the rotating grinding wheel closer to the wafer while being fed to the wafer, and the grinding wheel approaching and moving step, the grinding wheel bites the wafer and grinding is started. A grinding start detecting step for detecting this and the grinding start detecting step detecting that the grinding wheel has bitten on the wafer, then stopping the supply of the biting auxiliary liquid and supplying the grinding liquid to the wafer. And a grinding step for grinding the wafer with a grindstone. There is provided.

  According to the present invention, when the wafer is ground, the wafer is supplied with a biting auxiliary liquid that improves the biting of the grinding wheel against the wafer. And the risk of causing damage can be reduced.

It is a perspective view of a grinding device. It is a disassembled perspective view which shows a mode that a surface protection tape is stuck on the surface of a wafer. It is a perspective view which shows a holding | maintenance step. It is a perspective view which shows the grinding step of 1st Embodiment. It is a perspective view which shows a grinding stone approach moving step. It is a graph explaining a grinding start detection step. It is a perspective view which shows the grinding step of 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, an external perspective view of a grinding apparatus 2 suitable for carrying out the grinding method of the present invention is shown. Reference numeral 4 denotes a base of the grinding apparatus 2, and a column 6 is erected on the rear side of the base 4. A pair of guide rails 8 extending in the vertical direction is fixed to the column 6.

  A grinding unit (grinding means) 10 is mounted along the pair of guide rails 8 so as to be movable in the vertical direction. The grinding unit 10 includes a spindle housing 12 and a support portion 14 that holds the spindle housing 12, and the support portion 14 is attached to a moving base 16 that moves up and down along a pair of guide rails 8. Yes.

  The grinding unit 10 includes a spindle 18 rotatably accommodated in a spindle housing 12, a motor 20 that rotationally drives the spindle 18, a wheel mount 22 fixed to the tip of the spindle 18, and a detachable attachment to the wheel mount 22. And a mounted grinding wheel 24.

  The grinding apparatus 2 includes a grinding unit feed mechanism 34 including a ball screw 30 and a pulse motor 32 that move the grinding unit 10 in the vertical direction along the pair of guide rails 8. When the pulse motor 32 is driven, the ball screw 30 rotates and the moving base 16 is moved in the vertical direction.

  A recess 4a is formed on the upper surface of the base 4, and a chuck table mechanism 36 is disposed in the recess 4a. The chuck table mechanism 36 has a chuck table 38 and is moved in the Y-axis direction between a wafer attaching / detaching position A and a grinding position B facing the grinding unit 10 by a moving mechanism (not shown). 40 and 42 are bellows. An operation panel 44 is provided on the front side of the base 4 so that an operator of the grinding apparatus 2 can input grinding conditions and the like.

  Referring to FIG. 2, the semiconductor wafer 11 is made of, for example, a silicon wafer having a thickness of 700 μm, and a plurality of streets (division lines) 13 are formed in a lattice shape on the surface 11a. A device 15 such as an IC or an LSI is formed in each of the areas partitioned by.

  The semiconductor wafer 11 configured as described above includes a device region 17 in which the device 15 is formed, and an outer peripheral surplus region 19 that surrounds the device region 17. A notch 21 is formed on the outer periphery of the semiconductor wafer 11 as a mark indicating the crystal orientation of the silicon wafer.

  Prior to grinding the back surface 11 b of the wafer 11, a surface protective tape 23 is attached to the front surface 11 a of the wafer 11. The surface protective tape 23 is composed of, for example, an ultraviolet curable adhesive tape in which an ultraviolet curable adhesive material (glue layer) is disposed on one surface of polyethylene vinyl chloride, polyolefin, or the like.

  Next, as shown in FIG. 3, the wafer 11 is sucked and held by the chuck table 38 of the grinding device via the surface protection tape 23 to expose the back surface 11 b of the wafer 11. And as shown in FIG. 4, the grinding step of 1st Embodiment which grinds the back surface 11b of the wafer 11 with the grinding unit 10 is implemented.

  In FIG. 4, a grinding wheel 24 is detachably attached to a wheel mount 22 fixed to the tip of a spindle 18 of the grinding unit 10 by a plurality of screws 31. The grinding wheel 24 is configured by arranging a plurality of grinding wheels 28 in an annular shape at a free end (lower end) of a wheel base 26.

  In the grinding step of the first embodiment, while the biting auxiliary liquid 51 is supplied from the supply nozzle 46, the chuck table 38 is rotated in the direction indicated by the arrow a at, for example, 300 rpm, and the grinding wheel 24 is set in the direction indicated by the arrow b, for example. While rotating at 6000 rpm, the grinding unit feed mechanism 34 is driven to bring the grinding wheel 28 of the grinding wheel 24 into contact with the back surface 11 b of the wafer 11.

  The biting auxiliary liquid is composed of, for example, pure water containing fine abrasive grains, a surfactant, and various chemical mechanical polishing (CMP) slurries. Since grinding is performed while the auxiliary nozzle 51 bites into the back surface 11b of the wafer 11 from the supply nozzle 46, the grinding wheel 28 rotating at high speed is prevented from sliding on the back surface 11b of the wafer 11, and the grinding wheel 28 Can easily bite into the back surface 11 b of the wafer 11.

  While supplying the biting auxiliary liquid 51, the grinding wheel 24 is ground and fed downward by a predetermined amount at a predetermined grinding feed speed, and the back surface 11b of the wafer 11 is ground. While measuring the thickness of the wafer 11 with a contact type or non-contact type thickness measuring gauge, the wafer 11 is ground to a predetermined thickness, for example, 100 μm.

  Next, with reference to FIG. 5 thru | or FIG. 7, the grinding method of 2nd Embodiment of this invention is demonstrated. In the present embodiment, as shown in FIGS. 5 and 7, the supply nozzle 46 is selectively connected to the biting auxiliary liquid supply source 50 or the grinding liquid supply source 52 via the electromagnetic switching valve 48.

  In the grinding wheel approaching movement step shown in FIG. 5, the supply nozzle 46 is connected to the biting auxiliary liquid supply source 50 via the electromagnetic switching valve 48, and the biting auxiliary liquid 51 is held on the chuck table 38 from the supply nozzle 46. , While rotating the chuck table 38 in the direction indicated by the arrow a at 300 rpm, for example, the grinding wheel 24 is rotated in the direction indicated by the arrow b at 6000 rpm, for example, and the grinding unit feed mechanism 34 is driven to perform grinding. The unit 10 is ground and fed in the arrow z direction, and the grinding wheel 28 is brought into contact with the back surface 11 b of the wafer 11.

  When the grinding wheel 28 bites into the wafer 11 and grinding is started, the spindle load current value rapidly rises to a predetermined value as indicated by an arrow P in FIG. By detecting this rapid increase in the spindle load current value, it is detected that the grinding wheel 28 has bitten on the back surface 11b of the wafer 11 and grinding has started.

  When it is detected that the grinding has started, the electromagnetic switching valve 48 is switched to connect the supply nozzle 46 to the grinding fluid supply source 52 as shown in FIG. Then, while supplying a grinding liquid such as pure water from the supply nozzle 46, the chuck wheel 38 is rotated in the direction indicated by the arrow a at 300 rpm, for example, and the grinding wheel 24 is rotated in the direction indicated by the arrow b at 6000 rpm, for example. Then, the grinding unit feeding mechanism 34 is driven, and the grinding wheel 24 is ground and fed downward by a predetermined grinding feed speed in the arrow z direction, and the back surface 11b of the wafer 11 is ground. While measuring the thickness of the wafer 11 with a contact type or non-contact type thickness measuring gauge, the wafer 11 is ground to a predetermined thickness, for example, 100 μm.

  In each of the above-described embodiments, the example in which the grinding method of the present invention is applied to the semiconductor wafer 11 has been described. However, the grinding method of the present invention can be similarly applied to other wafers such as a sapphire wafer.

DESCRIPTION OF SYMBOLS 10 Grinding unit 11 Semiconductor wafer 23 Surface protection tape 24 Grinding wheel 28 Grinding wheel 38 Chuck table 46 Supply nozzle 48 Electromagnetic switching valve 50 Biting auxiliary liquid supply source 52 Grinding liquid supply source

Claims (2)

Wafer grinding method,
A holding step for holding the front side of the wafer with a chuck table;
Grinding the back surface of the wafer held by the chuck table with a grinding means having a grinding wheel, and
The method of grinding a wafer, wherein the grinding step is performed while supplying a biting auxiliary liquid that improves biting of the grinding wheel to the wafer. Wafer grinding method,
A holding step for holding the front side of the wafer with a chuck table;
Grinding wheel approach moving step for moving the rotating grinding wheel closer to the wafer and contacting the wafer while supplying a biting auxiliary liquid that improves the biting of the grinding wheel to the wafer to the wafer held by the chuck table;
A grinding start detection step for detecting that the grinding wheel bites the wafer and starts grinding after the grinding wheel approaching movement step;
A grinding step of grinding the wafer with the grinding wheel while stopping the supply of the biting auxiliary liquid and supplying the grinding liquid to the wafer after detecting that the grinding wheel has bitten the wafer in the grinding start detection step;
A method for grinding a wafer, comprising:

Images