JP2860671B2 - Dicing method for semiconductor wafer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor wafer dicing method for dividing a semiconductor wafer into individual devices.

[Conventional technology]

In manufacturing a semiconductor device such as a transistor or a semiconductor integrated circuit (IC), a large number of identical circuits are formed on one semiconductor wafer through various processes such as oxidation, diffusion, and vapor deposition of the semiconductor wafer. Next, a dicing operation is performed on the semiconductor wafer, and a large number of vertical and horizontal grooves are formed so as to surround each element, thereby separating each element (pellet). The pellet is bonded to a lead frame, wire-bonded, and resin-molded to be assembled in each semiconductor device.

As a method of separating the semiconductor wafer into pellets, a semiconductor wafer bonding tape is bonded to a ring frame, the semiconductor wafer is bonded to the tape, the ring frame, the semiconductor wafer together with the tape are fixed, and each is rotated with a rotating blade. Cut the periphery of the pellet vertically and horizontally to make kerfs. At the time of this cutting, the semiconductor wafer is fixed by adsorbing the ring frame to the fixing table with a magnet or the like and vacuum-sucking the tape to which the semiconductor wafer is attached from the fixing table side. This cutting is performed by rotating the rotating blade while applying a cooling liquid. However, since cutting chips adhere to the surface of the semiconductor wafer, the semiconductor wafer surface is quickly washed with the cleaning liquid after cutting. In this cleaning, the semiconductor wafer is fixed by magnetic force and vacuum suction as in the case of cutting, and high-pressure pure water (100 kg / cm ² ) is jetted for several tens of seconds while rotating with the fixed base at a low speed for cleaning. FIG. 5 shows a fixed state of the semiconductor wafer at the time of this cleaning. FIG. 2A is a plan view fixed to the chuck table 4 and FIG. 2B is a partially enlarged cross-sectional view thereof, wherein 1 is a ring frame, 2 is a tape, 3 is a semiconductor wafer, and 4 is a chuck which is a fixing table. The table 41 has a groove provided in the chuck table 4 and is structured to be sucked by a vacuum pump (not shown) provided below the chuck table 4. Therefore, when the vacuum pump is operated, the groove 41 of the chuck table 4 is in a vacuum state, the tape 2 is sucked, and the semiconductor wafer 3 is also moved to the chuck table 4.
Will be fixed to.

[Problems to be solved by the invention]

According to the above-described conventional method of fixing a semiconductor wafer, a groove 41 for vacuum suction is provided on the entire surface of the chuck table 4 to form the semiconductor wafer 3.
It is thought that it is strongly adhered because the suction force is applied to the entire surface. However, when vacuum suction is applied, the tape 2 is sucked into the groove 41 as shown in FIG.
Then, the pellet 31 obtained by cutting the semiconductor wafer 3 is separated. When pure water for cleaning is injected in this state, the pellets 31 are blown off and lost during cleaning, resulting in a poor yield. In many cases, the yield may be reduced by about 10%.

As a countermeasure, a kerf 32 to be inserted into the semiconductor wafer 3 at the time of dicing is inserted into the back surface of the semiconductor wafer 3 and is not separated into the respective pellets 31 but is partially connected to the back surface without being separated. A method of dividing the wafer 3 into the respective pellets 31 by dividing the wafer 3 is also considered. However, the method of separating the semiconductor wafer 3 later by splitting is preferable from the viewpoint of reliability because cracks enter the circuit portion of the semiconductor at the time of braking and lower the yield, or fragments at the time of the crack cause poor characteristics and the like. Absent.

[Means for solving the problem]

According to the present invention, in order to solve the above-described problems, the ring frame is sufficiently larger than the diameter of the semiconductor wafer to provide a gap portion which is only a tape portion between the semiconductor wafer and the ring frame, and at the time of cutting, a cut groove is formed to the back surface of the semiconductor wafer. A method is provided in which the semiconductor wafer is put into a state in which it can be separated into individual pellets, and as a suction method at the time of cleaning, the above-mentioned gap around the semiconductor wafer is mainly suctioned and fixed, and cleaning is performed with almost no suction from the lower surface of the semiconductor wafer. Things.

〔Example〕

FIG. 1 is a block diagram showing the steps of the semiconductor wafer dicing method according to the present invention. First, in the semiconductor wafer attaching step, as shown in FIG. 2, a semiconductor wafer attaching tape 2 is adhered to a ring frame 1 having a diameter sufficiently larger than the diameter of the semiconductor wafer 3, and a semiconductor wafer is attached to the center of the surface of the tape 2. 3 is attached. As a result, a gap where only the tape 2 exists can be secured between the ring frame 1 and the outer periphery of the semiconductor wafer 3. Next, the process proceeds to a cutting step, in which the ring frame 1 and the tape 2 to which the semiconductor wafer 3 is adhered are fixed to the chuck table by magnetic force and vacuum suction force, and cut grooves are formed in the vertical and horizontal directions of the semiconductor wafer by a rotary blade such as a diamond cutter. At this time, the cut groove extends to the back surface of the semiconductor wafer 3, and each cut piece is held with the tape 2 by an adhesive force. Next, the process proceeds to the washing and drying step. First, each pellet 31 cut as shown in a plan view in FIG. 3 (a) and a partially enlarged sectional view in FIG. 3 (b) is chucked through the tape 2 and the ring frame 1. Fix to table 4. That is, the ring frame 1 is attracted to the chuck table 4 by a magnetic force, and the tape 2 is attracted by the groove 41 provided on the chuck table 4 being sucked by a vacuum pump (not shown) to be in a vacuum state. At this time, the portion where the tape 2 is adsorbed is not provided as much as possible below the semiconductor pellet 31, and the groove 41 of the chuck table 4 is formed so that the tape 2 is adsorbed in the gap between the semiconductor wafer 3 and the ring frame 1. It is provided at a position to be an extension. The semiconductor pellet 31 is fixed to the chuck table 4 via the tape 2 in this manner, and the high-pressure pure water (100 kg / cm ² ) is jetted for several tens of seconds while rotating the entire chuck table 4 for cleaning, and chips and the like in the cutting process are removed. To eliminate. After the washing, the pure water is stopped, and the chuck table 4 is rotated while blowing nitrogen to dry.

The ring frame 1 with the pellets 31 thus washed and dried is automatically stored in a cassette, and is transferred to a die bonding step, in which the pellets 31 are picked up one by one and die-bonded to a lead frame.

FIG. 4 is a plan view showing a method of fixing to a chuck table according to another embodiment of the present invention. In this embodiment, the chuck table 4 is circular and the groove 41 is also circular.

〔The invention's effect〕

According to the present invention as described above, when cutting a semiconductor wafer, a kerf is completely formed up to the back surface of the semiconductor wafer,
Next, in the washing and drying step, the tape is vacuum-sucked at a portion where there is no semiconductor wafer, and hardly sticks from the back surface of the semiconductor pellet. No process required,
It is possible to significantly improve the yield without causing defects such as pellets and cracks and to reduce man-hours, and to contribute to improvement in reliability.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a manufacturing process of the present invention, FIG. 2 is a plan view showing a state where a wafer is attached in a semiconductor wafer attaching process, and FIG. 3 is a semiconductor wafer fixed on a chuck table in a washing and drying process. 5A is a plan view, FIG. 4B is a partially enlarged sectional view, FIG. 4 is a plan view showing another fixing method of the present invention, and FIG. FIG. 2A is a plan view showing a method of fixing a semiconductor wafer to a chuck table, and FIG. 2B is a partially enlarged view. 1 ... Ring frame, 2 ... Tape, 3 ... Semiconductor wafer, 4 ... Chuck table, 31 ... Semiconductor pellet, 41 ... Groove.

Claims (1)

(57) [Claims] 1. A step of bonding a tape in a ring frame circle and attaching a semiconductor wafer to the surface of the tape, and a cutting step of forming a predetermined kerf by a rotating blade for cutting the semiconductor wafer into pellets. Fixing the semiconductor wafer having the kerfs by vacuum suction, cleaning and drying the semiconductor wafer, wherein the ring frame is larger than the diameter of the semiconductor wafer in the semiconductor wafer attaching step. A gap is provided between the ring frame and the semiconductor wafer where only the tape is present, a kerf is formed in the cutting step up to the back surface of the semiconductor wafer, and a gap where only the tape is present in the cleaning and drying step. A dicing method for a semiconductor wafer, wherein the semiconductor wafer is fixed by vacuum suction and washed and dried.