JPS59134849A - Dicing method and adhesive sheet - Google Patents

Abstract

PURPOSE:To prevent charging of a wafer by bonding a conductive adhesive sheet on the back surface of the wafer and dicing the wafer from the surface while grounding the sheet. CONSTITUTION:An adhesive sheet 2 is bonded under uniform tension to a conductive annular jig 5. A wafer 1 is bonded to the center of an adhesive unit 3 with the pattern disposed upside. The sheet 2 is clamped by a clamper 7 on a base 6, and cut in the degree so as not to cut the sheet 2 rapidly in high depth by a cutting blade 8. During cutting, a pure water (which is nonconductive) is supplied. Static electricity produced in this case is grounded through the wafer 1, a conductive adhesive unit 4, the jig 5 and the clamper 7, and is not charged at the wafer. According to this structure, the damage of the pattern on the wafer due to the charging can be avoided, and the wafer can be cut deeply almost to the position immediately before cutting out. Accordingly, even if a breaking step is omitted, the pellets can be picked up, and the damage of the wafer due to the interference with adjacent pellet can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for dicing wafers, etc., and an adhesive sheet used in the method.

Generally, the manufacturing process of semiconductor devices includes a cutting process in which a wafer is divided into pellets using a dicing saw.

In such a dicing method, the wafer is cut halfway through its thickness, and then the wafer is divided into individual pellets by braking.

Including the braking process in this way not only increases the number of processes (but also allows adjacent pellets to interfere with each other during braking, causing damage to the pellets.

For this reason, it is desirable to cut the wafer fully or almost completely with a cutting tool.
As a dicing method to achieve this, a method has been proposed in which an adhesive sheet is attached to the back surface of the wafer, and the adhesive sheet prevents the pellets from dispersing after full cutting.

However, when dicing is performed with an adhesive sheet attached to the back of the wafer, friction between the dicing tool and the cut surface of the wafer,
It has been discovered that cleaning water (pure water) and friction between the blades can cause static electricity to build up on the wafer, causing damage to the circuits formed on the wafer.

The present invention was made based on such research, and
The purpose is to provide a dicing method that can prevent static electricity from forming on objects to be diced, and
The purpose of this invention is to provide an adhesive sheet that can be used directly for implementation.

Hereinafter, the present invention will be explained according to embodiments shown in the drawings.

FIGS. 1 and 2 are a plan view and a longitudinal sectional view illustrating an embodiment of the present invention.

In this embodiment, the adhesive sheet 2 to be adhered to the back surface of the wafer 1 is a sheet base material 3 formed of a thin film having a larger area than the wafer 1 using a material such as synthetic resin. It has an adhesive part 4 which is coated or the like, and this adhesive part 4 is given conductivity by, for example, adding a conductive substance to the adhesive.

Next, an embodiment of the dicing method according to the present invention using the pressure-sensitive adhesive sheet having the above structure will be described.

The adhesive sheet 2 is uniformly adhered to a ring-shaped adhesion jig 5 made of a conductive material with an appropriate tension. The wafer 1 is adhered to approximately the center of the adhesive portion 3 of the adhesive sheet 2 with the patterned surface facing upward.

Thereafter, as shown in FIG. 2, the adhesive sheet 2 to which the wafer 1 is adhered is placed on the upper surface of the table 6 of the dicing machine, and the jig 5 is held fixedly by an appropriate ramp puff. As a result, Ueno\5 is fixed to the table 6.

Once the wafer 1 is fixed, the wafer 1 is cut and diced by a dicing tool 8 placed thereon. At this time, the guissing tool 8 cuts into the wafer 1 as deeply as possible without risk of cutting the adhesive sheet 2.

During this cutting process, pure water as cutting fluid or cleaning water is sprayed and supplied.

At this time, the wafer 1 tends to be charged with static electricity due to friction between the dicing saw 8 and the cut end of the wafer 1 and friction between the pure water and the blade.

However, this static electricity is grounded via the wafer 1, the conductive adhesive part 4, the jig 5, and the clamper 7, as shown by the broken line arrow in FIG. 2, so that the wafer is not charged.

By the way, since pure water is non-conductive, it cannot prevent electrostatic charging.

According to this embodiment, it is possible to prevent the wafer from being charged with static electricity during dicing, so it is possible to avoid destroying the pattern on the wafer due to the static electricity charged on the wafer.

Moreover, since the pellets after dicing the wafer are connected by the adhesive sheet to maintain their integrity, it is possible to make enough cuts to almost divide the wafer. In this way, when the wafer is almost fully cut by the dicing saw, even if the braking step is omitted, each pellet that has been almost fully cut can be exceptionally pisoqua-knobbed. In this pickup, since the cut end of each pellet reaches the end, a phenomenon in which adjacent pellets interfere with each other does not occur. That is, the interference phenomenon occurs because the uncut portion of the wafer is diagonally broken in accordance with the silicon crystal direction during the braking process, so the interference phenomenon does not occur in a state where there is no uncut portion of the wafer.

Therefore, according to this embodiment, not only can the braking process be omitted, but also damage accidents caused by interference between pellets can be prevented, and the product yield is improved.

FIG. 3 shows another embodiment of the present invention. In this embodiment, the adhesive sheet 2A and the sheet base material 3A are made of a conductive material such as aluminum or conductive synthetic resin to make the adhesive sheet conductive. It is formed into a thin film with a

After the wafer 1 is adhered, the adhesive sheet 1-2A is placed and held on a table 6A consisting of a vacuum suction chuck or the like. Thereby, the wafer 1 is fixed to the table 6A.

The static electricity that tries to charge the wafer 1 during dicing is
As shown by the broken line arrow in FIG. 3, the wafer 1 is grounded through the wafer 1, the conductive adhesive part 4, the conductive sheet base material 3A, and the table 6A, so that static electricity does not accumulate on the wafer 1. Prevented.

Note that the shape, structure, etc. of the pressure-sensitive adhesive sheet are not limited to those in the above embodiments, and in short, it is sufficient that the pressure-sensitive adhesive sheet has conductivity to draw out static electricity that may be charged on an object to be diced, such as a wafer.

Further, the structure for holding and fixing a wafer or the like adhered to an adhesive sheet during dicing is not limited to the above embodiment.

As described above, according to the present invention, it is possible to prevent static electricity from being charged on an object to be diced, such as a wafer, during dicing.

[Brief explanation of the drawing]

1 and 2 are a plan view and a vertical sectional view showing one embodiment of the invention, and FIG. 3 is a longitudinal sectional view showing another embodiment of the invention. 1... Wafer, 2,2A... Adhesive sheet, 3.3A
...Sheet base material, 4...Adhesive part, 5...Jig, 6
, 6A...° table, 7... clamper, 8...
dicing saw.

Claims (1)

[Claims] 1. After adhering a conductive adhesive sheet to the back surface of the object to be diced, while electrically grounding the adhesive sheet,
A dicing method that cuts into the surface of the object to be diced. 2. The dicing method according to claim 1, wherein the adhesive sheet is stuck to a ring-shaped jig. 3.-A pressure-sensitive adhesive sheet having an adhesive portion on its surface, characterized in that at least the adhesive portion has conductivity.