JPH0319704B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a semiconductor manufacturing method in which pellets are manufactured by dividing a semiconductor wafer into pieces using a dicing saw.

2. Description of the Related Art In the semiconductor manufacturing process, there is a step of cutting a semiconductor wafer into individual pellets, and a specific example thereof is shown below with reference to FIGS. 2 and 3. In the figure, 1 is a semiconductor wafer (hereinafter simply referred to as a wafer), 2 is an adhesive sheet, 3 is an adhesive layer bonded and formed on the adhesive sheet 2, and 4 is a dicing saw (or referred to as a dicer) used to cut the wafer 1. After pasting it on the mounting sheet 2, use the dicing saw 4 to
The pellets are completely cut (through-cut) in the X and Y directions to be finely divided into pellets 1a, 1a, . In order to completely cut the wafer 1 with the dicing saw 4, the blade 4a rotating perpendicularly to the surface of the wafer 1 is pressed and cut into a part of the adhesive sheet 2, and then moved parallel to the surface of the wafer 1. At this time, for the adhesive layer 3, a pressure-sensitive adhesive has conventionally been used that can obtain the desired adhesive strength by applying pressure, but there was a problem that it was difficult to peel off the pellets after dicing, so Ultraviolet curing adhesives have been used. The irradiated portion of the UV-curable adhesive is cured by UV irradiation, and its adhesive strength decreases.After the dicing is completed, UV rays are irradiated from the adhesive sheet 2 side to weaken the adhesive strength of the adhesive layer 3. to facilitate pellet peeling.

Problems to be Solved by the Invention By the way, during the above-described dicing of the wafer 1, the adhesive layer 3 creates a large frictional resistance against the dicing saw 4, which shortens the life of the blade 4a and increases costs. Further, as shown in FIG. 4, the adhesive adheres to the surface _4a1 of the blade 4a, reducing its sharpness and increasing the friction of the dicing saw 4 against the pellets 1a, causing the pellets 1a to be thrown off during dicing. Furthermore, during dicing, since the adhesive layer 3 is elastic in an uncured state, a partial force is applied to the wafer 1 due to the cuts made by the blade 4a. Therefore, the wafer 1 undergoes repeated partial deformation and restoration, resulting in small local vibrations, and when this vibration is repeated, the pellets 1a tend to peel off during dicing even if the adhesive strength is strong. Specifically, when a wafer with a mirror-finished back surface was adhered to an ultraviolet curable adhesive sheet by applying 20 g of pressure for 15 seconds and half-cut into 2 mm square pellets, the defective rate of pellets such as scratches, cracks, and chips was 7.72%. Of these, cracks and chips accounted for 2.13%.

Means for Solving the Problems The present invention provides a semiconductor manufacturing method in which a semiconductor wafer is attached to an adhesive sheet on which an ultraviolet curable adhesive layer is formed, and the wafer is completely cut with a dicing saw and finely divided into pellets. After pasting the wafer, the wafer pasting part of the adhesive sheet is kept flat at least until the wafer is subdivided into pellets, and the adhesive layer is irradiated with ultraviolet rays to harden it prior to the dicing operation. Features.

Effect If a wafer is attached to an adhesive sheet having an ultraviolet curable adhesive layer, and the wafer attachment part of the adhesive sheet is kept flat and the adhesive layer is cured prior to dicing, the frictional resistance against the dicing saw will be reduced. and the wafer does not undergo minute vibrations during dicing.

EXAMPLE A semiconductor manufacturing method according to the present invention will be described below with reference to FIG. The same reference numerals as in FIG. 2 indicate the same parts. In the figure, 1 is a wafer, 2 is an adhesive sheet,
3 is an adhesive layer made of an ultraviolet curable adhesive sheet adhered to and formed on the adhesive sheet 2, and 4 is a dicing saw. After the wafer 1 is attached to the adhesive sheet 2, it is kept flat by a retaining ring (not shown) to prevent bending or twisting.

In the above configuration, the wafer 1 is placed on the dicing saw 4.
When completely cutting, the adhesive layer 3 made of an ultraviolet curable adhesive is cured by irradiating ultraviolet rays 5 from the adhesive sheet 2 side prior to dicing. In this case, the adhesive force of the adhesive layer 3 becomes weaker, but since it is hardened, the plate 4
Even if a cuts into the wafer 1, the force due to the cut is applied to the entire surface of the wafer 1. Therefore, there is no slight deformation of the wafer 1 due to the cuts made by the blade 4a during dicing, and even if the adhesive force of the adhesive layer 3 becomes weak, the pellets 1a are difficult to peel off during dicing. Then, since the adhesive force becomes weaker, the adhesive layer 3
The frictional resistance of the dicing saw 4 due to this decreases, and the life of the blade 4a becomes longer. Also, adhesive layer 3
is hardened and the adhesive does not adhere to the surface 4a of the blade 4 during dicing, so the friction of the dicing saw 4 against the pellets 1a is reduced and the pellets 1a are not thrown off during dicing.

The adhesive force between the cured adhesive layer 3 and the wafer 1 is determined by using a wafer with a mirror-finished back surface as an adhesive sheet.
An item whose initial adhesive force was 40 g when bonded by applying pressure for 15 seconds at 20 g will become 20 g when irradiated with an ultraviolet light source with an irradiance of 50 mW/cm ² and an irradiation energy of 100 mJ/cm ²
and 10g at 1000mJ/ ^cm2 .

On the other hand, the adhesive strength against lateral shear was measured in the unirradiated state.
260g becomes 300g at 100mJ/ ^cm2 ,
It becomes 400g at 1000mJ/cm ² , and the strength against lateral slippage increases with ultraviolet irradiation, contrary to the adhesive strength.

As a result, the defect rate of pellets completely cut by the present invention was 0.71%, of which there were no cracks or chips.
It decreased to 0.07%.

Effects of the Invention According to the present invention, a semiconductor wafer is attached to an adhesive sheet on which an ultraviolet curable adhesive layer is formed, and the adhesive is cured by irradiating ultraviolet rays prior to dicing. The pellets are less likely to peel off, and the pellets are not thrown off by the dicing saw, improving yield. Furthermore, the life of the dicing saw is extended, and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a side cross-sectional view of a semiconductor wafer during dicing showing an application example of the semiconductor manufacturing method according to the present invention, and FIGS. 2 and 3 are semiconductors during dicing manufactured by a conventional semiconductor manufacturing method. of wafer
Each side sectional view seen from the XY direction, FIG. 4 is a partial side sectional view of the semiconductor wafer during dicing. 1...Semiconductor wafer, 1a...Pellet, 2...
... Adhesive sheet, 3... Adhesive layer, 4... Dicing saw, 5... Ultraviolet rays.

Claims (1)

[Claims] 1. In a semiconductor manufacturing method in which a semiconductor wafer is attached to an adhesive sheet on which an ultraviolet curable adhesive layer is formed, and the wafer is completely cut with a dicing saw and finely divided into pellets, after the semiconductor wafer is attached, at least the wafer is A semiconductor manufacturing method characterized in that a portion of the adhesive sheet to which the wafer is attached is kept flat until it is finely divided into pellets, and the adhesive layer is cured by irradiating ultraviolet rays prior to dicing.