JP2005150360A - Method for processing wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure efficient cleaning effect without lowering the service life of a grinding stone such as a cutting blade or the like, and to keep the quality of an object to be processed when the object is cut or polished by the grinding stone while a processing water is used. <P>SOLUTION: An activated water wherein a pure water is mixed with either of hydrogen molecule or oxygen molecule is generated, and while it is supplied to a wafer, the wafer is polished by a processing means. An object to be processed is hard to be contaminated by contaminant, and its quality is not degraded. Furthermore, a metal forming a grinding stone is not corroded, thereby prolonging the service life of the grinding stone. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for performing processing while supplying processing water to a wafer.

  A semiconductor wafer formed by dividing a plurality of circuits such as ICs and LSIs by streets is divided into individual semiconductor chips by cutting the streets vertically and horizontally by a cutting device which is a kind of processing device.

  At the time of street cutting, the cutting blade constituting the cutting device cuts into the wafer while rotating at a high speed. Therefore, in order to cool the contact portion between the wafer and the cutting blade, cutting water is jetted as processing water to the contact portion. Further, the cutting water prevents the chips generated by the cutting from adhering to the wafer, and also serves to clean the surface of the wafer by removing the attached chips.

  As this cutting water, when pure water is used, static electricity is likely to be generated, so that carbon dioxide is mixed with pure water, and cutting is performed while jetting the cutting water onto the surface of the wafer. While cooling the contact part of a braid | blade and a wafer, it prevents that the surface of a wafer is contaminated with cutting waste (for example, refer patent document 1, patent document 2, patent document 3).

JP 2003-29165 A JP-A-10-321562 Japanese Patent Publication No. 6-105750

  However, since the cutting water activated by the mixing of carbon dioxide has strong acidity, there is a problem that the base metal constituting the cutting blade is eroded by the cutting water and the life of the cutting blade is significantly reduced. Also, there is a problem that the bonding pad formed on the surface of the semiconductor chip is eroded and the quality of the semiconductor chip is deteriorated. Such a problem is a problem that occurs not only in cutting processing but also in other processing using a grindstone.

  Therefore, the problem to be solved by the present invention is that, in processing using a grindstone such as cutting and grinding, the life of the grindstone such as a cutting blade is not reduced and adhesion of contamination such as cutting waste and grinding waste is prevented. It is to prevent degradation of the quality of the work piece.

  The present invention relates to a wafer using a chuck table that holds a wafer, a processing unit that processes the wafer held by the chuck table with a grindstone, and a processing water supply unit that supplies processing water to the wafer. In this processing method, the processing water is activated water in which either hydrogen molecules or oxygen molecules are mixed into pure water, and the processing water is supplied to the wafer by the processing water supply means and processed into the wafer. Provided is a wafer processing method for processing by means.

  As the processing apparatus, for example, there is a cutting apparatus provided with a cutting blade, but an apparatus for performing processing with other grindstones such as a grinding apparatus is also included.

  The activated water is preferably composed of pure water mixed with 1.0 to 2.0 ppm of hydrogen molecules, or purified water mixed with 20 to 40 ppm of oxygen molecules.

  Further, the processing water supply means may be provided with an ultrasonic wave oscillating unit, and ultrasonic waves may be supplied from the ultrasonic wave oscillating unit to the activated water during processing.

  Further, 0.5 to 1.5 ppm of ammonia may be mixed into the activated water.

  In the present invention, the activated water in which hydrogen molecules or oxygen molecules are mixed into pure water is used as the processing water, and the processing is performed while supplying the processing water to the processing site. Therefore, the quality of the wafer can be improved, the metal constituting the grindstone is not eroded by the processing water, and the wafer is not eroded. For example, when the wafer is a semiconductor wafer, the bonding pads formed on the semiconductor chip are not eroded and the quality of the individual semiconductor chips is not deteriorated.

  Furthermore, since the ultrasonic wave is added to the processed water, the cleaning effect can be further increased, and the cleaning effect can be enhanced by mixing ammonia in the processed water.

  A cutting apparatus 1 shown in FIG. 1 is a kind of processing apparatus to which the present invention is applied. This cutting apparatus 1 carries out a wafer from a cassette 2a containing a wafer such as a semiconductor wafer and carries in / out means 2 for storing the cut wafer in a cassette 2a, and a wafer carried out from the cassette 2a or a cassette 2a. A temporary placement area 3 on which a wafer to be processed is temporarily placed, a first transport means 4 for transporting the wafer, a chuck table 5 for holding the wafer, and an imaging means 6a for the wafer held on the chuck table 5 Alignment means 6 for picking up an image and detecting a processing region to be processed, cutting means 7 as a processing means for cutting the wafer held on the chuck table 5, and cleaning means 8 for cleaning the wafer after cutting. And a second transfer means 9 for transferring the cut wafer from the chuck table 5 to the cleaning means 8.

  Below, the semiconductor wafer W shown in FIG. 1 is mentioned as an example of a wafer, and the case where this is cut is demonstrated. As shown in FIG. 1, the semiconductor wafer W to be cut is integrated with the frame F via the holding tape T, and the semiconductor wafer W accommodated in the cassette 2a in this state is unloaded. After being carried out to the temporary placement area 3 by the insertion means 2, it is conveyed and held by the first conveying means 4 to the chuck table 5. The semiconductor wafer W held on the chuck table 5 is positioned immediately below the alignment means 6 by the movement of the chuck table 5 in the + X direction.

  Then, after the surface of the semiconductor wafer W is imaged by the imaging means 6a constituting the alignment means 6, and the processing region is detected by image processing such as pattern matching, the chuck table 5 is further moved in the + X direction to thereby move the semiconductor wafer. W is positioned in the vicinity of the cutting means 7.

  As shown in FIG. 2, the cutting means 7 has a configuration in which a cutting blade 71 is attached to the tip of a rotatable spindle 70. The cutting blade 71 includes an outer peripheral grindstone portion 71a and a hub 71b. The grindstone portion 71a has a configuration in which diamond abrasive grains are hardened with a base metal such as nickel. Further, on both sides of the cutting blade 71, processing water supply means 10 that ejects the processing water to the contact portion between the cutting blade 71 and the semiconductor wafer W is disposed. The base of the processing water supply means 10 includes an ultrasonic oscillator 10a that oscillates ultrasonic waves.

The two processing water supply means 10 are connected to the dissolving part 11. The melting part 11 is connected to a pure water tank 14 and a gas generator 15 through valves 12 and 13, respectively, and is processed by the melting part 11, the valve 12, the valve 13, the pure water tank 14 and the gas generator 15. The water production | generation part 16 is comprised. The gas generator 15 can generate hydrogen gas H ₂ or oxygen gas O ₂ , and the flow rate of the pure water in the pure water tank 14 and the gas generated in the gas generator 15 is adjusted by valves 12 and 13, respectively. Then, it flows into the dissolution part 11, where activated water (hydrogen water or oxygen water) is generated by dissolving the gas in pure water.

  The chuck table 5 holding the semiconductor wafer W moves in the X-axis direction, and the cutting means 7 descends while the cutting blade 71 rotates at a high speed, whereby the semiconductor wafer W is cut. At this time, activated water generated in the dissolving portion 11 is ejected as processing water 100 to the contact portion between the cutting blade 71 and the semiconductor wafer W.

  Although cutting waste (contamination) is generated by performing cutting in this way, it is possible to prevent the contamination from adhering to the surface of the semiconductor wafer W by the activated water, and therefore, formed by cutting the semiconductor wafer W. The chip quality is not degraded. In particular, it is more effective when the semiconductor wafer W has a large influence on the quality due to contamination as in a CCD. Further, the base metal constituting the grindstone 71a of the cutting blade 71 is not eroded and the bonding pads constituting the semiconductor chip are not eroded.

  The activated water used as the processing water is preferably one in which 1.0 to 2.0 ppm of hydrogen molecules are mixed in pure water, or one in which 20 to 40 ppm of oxygen molecules are mixed in pure water. Further, ammonia may be added to the activated water in the dissolving portion 11 shown in FIG. It is preferable to add about 0.5 to 1.5 ppm of ammonia, for example.

  The cleaning effect by the activated water is that the redox potential decreases due to the mixing of hydrogen molecules and the reducing power increases, and the electrostatic repulsion by making the zeta potential of the surface of the semiconductor wafer W and the surface of the contamination negative. Brought by power. Further, when ammonia is mixed in the activated water, the oxidation-reduction potential is further lowered for the former, and the zeta potential of contamination is changed for the latter, and the cleaning effect is further enhanced.

  When the machining water 100 is supplied, the ultrasonic wave may be oscillated from the ultrasonic oscillation unit 10a to give vibration to the machining water. When ultrasonic waves are supplied to hydrogen water, highly reactive surplus H radicals are generated, and the surplus H radicals effectively act on the semiconductor wafer W or the surface of the contamination, so that the semiconductor wafer W against the contamination. It is thought that it encourages the withdrawal. The frequency of the ultrasonic wave is preferably, for example, 1 to 2 MHz.

  In addition, it is also possible to perform the cutting while the semiconductor wafer W is submerged in the processing water by retaining the processing water 100 ejected from the processing water supply means 10 on the semiconductor wafer W. Water can be used.

  Further, as shown in FIG. 3, the water curtain 170 may be formed by activated water ejected from the nozzle 17.

  The semiconductor wafer W after cutting is transferred to the cleaning means 8 by the second transfer means 9 shown in FIG. In the cleaning means 8, the cleaning water is jetted to clean the semiconductor wafer W, and the activated water generated in the dissolving part 11 shown in FIG. 2 can also be used for the cleaning water. By using activated water, it is possible to wash away effectively even if contamination generated during cutting adheres.

  The semiconductor wafer W thus cleaned by the cleaning means 8 is transported to the temporary placement region 3 in a state of being integrated with the frame F via the holding tape T, and then accommodated in the cassette 2a by the carry-in / out means 2.

  In the above description, the cutting apparatus has been described as an example of the processing apparatus. However, for example, a grinding apparatus that grinds the surface of the wafer is also a processing apparatus, and the present invention is applied.

  For example, the grinding apparatus 200 shown in FIG. 4 includes a chuck table 201 that holds a workpiece, and a grinding means 202 that is a processing means for polishing the workpiece held on the chuck table 201.

  The grinding means 202 has a configuration in which a grinding wheel 205 is fixed to the tip of a rotatable spindle 203 via a mounter 204, and a grinding wheel 206 is fixed to the lower surface of the grinding wheel 205. In addition, a machining water flow passage 207 through which the machining water flows is formed inside the grinding wheel 205.

  For example, at the time of grinding the surface of the semiconductor wafer W1, the grinding means 202 descends while the grinding wheel 206 rotates, so that the rotating grinding wheel 206 comes into contact with the semiconductor wafer W1 and grinding is performed. The processing water 210 flowing through the passage 207 is supplied to the contact portion between the grinding wheel 206 and the semiconductor wafer W1 to be cooled. That is, the grinding means 202 includes processing water supply means.

  As in the case of cutting, activated water obtained by mixing hydrogen gas or oxygen gas into pure water can be used as the processing water to prevent grinding dust (contamination) from adhering to the grinding surface. Therefore, the quality of the semiconductor wafer W1 is not deteriorated.

  Pure water or various activated waters generated in the melting part 11 shown in FIG. 2 are used as processing water without supplying ultrasonic waves, and the semiconductor wafer is vertically and horizontally using the cutting apparatus 1 shown in FIG. Cutting (dicing). Then, the surface of the semiconductor chip after dicing was imaged by the imaging unit 6 a after dicing, and the number of contaminants attached to the surface was obtained by image processing by the alignment unit 6. The result was as follows.

(1) When pure water was used as the processing water, the number of contaminants of 0.12 μm or more was 95 / cm ² .

(2) The number of contaminants of 0.12 μm or more was 3 / cm ² when activated water in which 1.2 ppm of hydrogen molecules were mixed in pure water was used as the processed water.

(3) The number of contaminants of 0.12 μm or more in the case of using activated water in which 1.2 ppm of hydrogen molecules are mixed in pure water and 1 ppm of ammonia is mixed as processed water is 1 piece / cm ^2. Met.

(4) The number of contaminants of 0.12 μm or more was 24 / cm ² when activated water in which 30 ppm oxygen molecules were mixed in pure water was used as the processed water.

  The present invention can be applied to the production of high-quality wafers and chips that are not contaminated by contamination.

It is a perspective view which shows an example of the cutting device which is a kind of processing apparatus. It is a perspective view which shows a mode that a semiconductor wafer is cut with ejection of process water. It is a perspective view which shows a mode that a water curtain is formed and a semiconductor wafer is cut. It is explanatory drawing which shows a mode that the surface of a semiconductor wafer is ground using the grinding device which is an example of a processing apparatus.

Explanation of symbols

1: Cutting device 2: Loading / unloading means 2a: Cassette 3: Temporary placement area 4: First transport means 5: Chuck table 6: Alignment means 6a: Imaging means 7: Cutting means 70: Spindle 71: Cutting blade 8: Cleaning Means 9: Second transport means 10: Processing water supply means 10a: Ultrasonic oscillator 16: Processing water generation part 11: Dissolution part 12, 13: Valve 14: Pure water tank 15: Gas generator W: Wafer T: Holding tape F: Frame 17: Nozzle 170: Water curtain 100: Processing water 200: Grinding device 201: Chuck table 202: Grinding means 203: Spindle 204: Mounter 205: Grinding wheel 206: Grinding wheel 207: Working water flow passage

Claims (6)

Wafer processing using a processing device comprising a chuck table for holding a wafer, processing means for processing the wafer held by the chuck table with a grindstone, and processing water supply means for supplying processing water to the wafer A method,
The processing water is activated water obtained by mixing either hydrogen molecules or oxygen molecules in pure water, and the processing means is supplied to the wafer while supplying the activated water to the wafer by the processing water supply means. The processing method of the wafer which processes by.   The wafer processing method according to claim 1, wherein the processing device is a cutting device, the processing unit is a cutting unit including a rotatable cutting blade, and the processing is cutting.   The wafer processing method according to claim 1, wherein the activated water is configured by mixing 1.0 to 2.0 ppm of hydrogen molecules in pure water.   3. The wafer processing method according to claim 1, wherein the activation water is configured by mixing 20 to 40 ppm of oxygen molecules in pure water. 4.   5. The wafer according to claim 1, wherein the processing water supply unit includes an ultrasonic oscillation unit, and ultrasonic waves are supplied from the ultrasonic oscillation unit to the activated water during the processing. Processing method.   The wafer processing method according to claim 1, wherein 0.5 to 1.5 ppm of ammonia is mixed in the activated water.

Images