JP2001308037A - Method for dicing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for dicing, capable of preventing an electrical short circuit of an element in a semiconductor chip by sufficiently oxidizing a cut surface of a wafer, in the case of cutting the wafer and dividing the wafer into semiconductor chips. SOLUTION: The method for dicing comprises the step of cutting the wafer 5, formed with a semiconductor element into individual semiconductor chips 5a, while applying cutting water to a dicing saw 7. In this case, as the water, an oxidized water for oxidizing the cut surface of the after is used. As the oxidized water, it is preferred to use hydrogen peroxide water, oxygen-dissolved water, ozone-added water or the like. Thus, the cut surface of the chip can be oxidized sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a dicing method for separating a wafer into chips. In particular, the present invention relates to a dicing method capable of preventing an element portion in a chip from being electrically short-circuited.

[0002]

2. Description of the Related Art A conventional dicing method will be described below with reference to FIG. FIG. 1 is a diagram illustrating a dicing method according to an embodiment of the present invention, which is used here for convenience of description.

[0003] First, the back surface of a wafer 5 to be diced is attached to an adhesive sheet 3, and the adhesive sheet 3 is fixed to the flat ring 1. The pressure-sensitive adhesive sheet 3 is provided to prevent the individually separated semiconductor chips 5a from scattering or to facilitate handling after dicing.

Next, a disk-shaped cutting blade (dicing saw)
The dicing saw 7 is rotated as indicated by an arrow, and the wafer 5 is cut along a scribe line while spraying cutting water on the dicing saw 7. Thus, the chips are separated into individual chips 5a.

[0005] As the cutting water, pure water or a liquid obtained by dissolving carbon dioxide gas in pure water is used. The reason for using the cutting water is to suppress the temperature rise of the wafer 5 due to the heat generated at the time of cutting and to take measures against static electricity. If no countermeasures against static electricity are taken, static electricity accumulates on the wafer due to dicing, and when the static electricity is discharged from the wafer 5 or the chip 5a, semiconductor elements such as internal circuits may be destroyed.

[0006]

Since the silicon substrate is exposed at the cut portion after dicing the wafer, it is necessary to oxidize the cut surface in order to secure insulation from elements inside the chip. In addition, the cutting surface is oxidized by cutting water sprayed on the cutting surface during dicing.

However, pure water or a liquid in which carbon dioxide gas is dissolved, which is used as cutting water in the above-mentioned conventional dicing method, has insufficient oxidizing power, so that the cut surface of the wafer cannot be sufficiently oxidized. . Therefore, the active element portion of the chip is exposed on the cut surface,
Depending on the device structure, assembling, and mounting structures, the cut surface may be electrically short-circuited with the active element portion.

More specifically, for example, when the burrs of Al generated at the end of the chip come into contact with the cut surface, the active element in the chip may be short-circuited. Further, as shown in FIG. 2, the cut surface of the chip 5a may be short-circuited due to the rise of the conductive adhesive 13 during die bonding.

FIG. 2 is a sectional view showing a state in which a chip divided by a conventional dicing method is die-bonded to a lead frame.

A chip 5a is die-bonded on a die pad 11a of the lead frame 11 via a conductive adhesive 13. The electrode pads on the chip 5a and the leads 11b are electrically connected by bonding wires 15.

When the chip 5a is bonded to the die pad 11a, the excess conductive adhesive 13 bulges into contact with the cut surface (end surface) of the chip 5a, and as a result, the active element portion in the chip is electrically short-circuited. Resulting in.
In order to avoid such a short circuit, the cut surface of the chip is sufficiently oxidized to secure insulation.

The present invention has been made in view of the above circumstances, and an object of the present invention is to sufficiently oxidize a cut surface when a wafer is cut and divided into semiconductor chips so that the inside of the chip can be reduced. It is an object of the present invention to provide a dicing method capable of preventing an element portion from being electrically short-circuited.

[0013]

A dicing method according to the present invention is a dicing method for cutting a wafer on which semiconductor elements are formed into individual semiconductor chips while applying cutting water to a cutting blade. Is oxidized water that oxidizes the cut surface of the wafer.

According to the above-mentioned dicing method, the wafer is cut into individual semiconductor chips while oxidizing water having a strong oxidizing power is applied to the cutting blade. The cut surface can be sufficiently oxidized. Thereby, the active element inside the chip and the outside can be completely insulated. Therefore, even for various device structures, assembling and mounting structures, it is possible to prevent an electrical short circuit with the active element portion on the chip cutting surface.

In the dicing method according to the present invention, it is preferable that the oxidized water contains hydrogen peroxide or oxygen-dissolved water.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view illustrating a dicing method according to an embodiment of the present invention.

First, the back surface of the wafer 5 to be diced is attached to the adhesive sheet 3, and the adhesive sheet 3 is fixed to the flat ring 1. The pressure-sensitive adhesive sheet 3 is provided to prevent the individually separated semiconductor chips 5a from scattering or to facilitate handling after dicing.

Next, a disk-shaped cutting blade (dicing saw)
7 is rotated as indicated by an arrow, and cutting water (not shown) discharged from a nozzle (not shown) is blown onto the dicing saw 7 to cut the wafer 5 along a scribe line. Thus, the chips are separated into individual chips 5a.

Here, oxidized water having a strong oxidizing power is used as the cutting water. As the oxidized water, it is preferable to use, for example, hydrogen peroxide water, oxygen-dissolved water, ozone-added water, and the like.

By using the oxidized water as described above,
Not only can the cut surface of the chip be efficiently oxidized, but also the temperature rise of the wafer 5 due to heat generated during cutting can be suppressed, and static electricity generated during dicing can be prevented.

According to the above embodiment, since the wafer 5 is cut into individual semiconductor chips 5a while oxidizing water having a high oxidizing power is applied to the dicing saw 7, the oxidizing water is also applied to the chip cutting surface. The cut surface of the chip after dicing can be sufficiently oxidized. As a result, the cut surface can be electrically insulated from the outside, and the active element inside the chip can be completely insulated from the outside. Therefore, it is possible to prevent an electrical short circuit with the active element portion on the chip cutting surface for various device structures, assembling and mounting structures. That is, in the case of the assembly structure as shown in FIG. 2, even if the conductive adhesive creeps on the chip end surface, the electric trouble unlike the case of using the conventional dicing method does not occur.

The present invention is not limited to the above embodiment, but can be implemented with various modifications. For example,
As long as the oxidizing water has a sufficient oxidizing power, oxidizing water other than the oxidizing water described in the present embodiment can be used.

[0023]

As described above, according to the present invention, the wafer is cut into individual semiconductor chips while oxidizing water having a strong oxidizing power is applied to the cutting blade. Therefore, the cut surface of the chip can be sufficiently oxidized at the time of dicing, thereby preventing the element portion in the chip from being electrically short-circuited.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a dicing method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which a chip divided using a conventional dicing method is die-bonded to a lead frame.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flat ring 3 Adhesive sheet 5 Wafer 5a Semiconductor chip 7 Cutting blade (dicing saw) 11 Lead frame 11a Die pad 13 Conductive adhesive 15 Bonding wire

Claims (2)

[Claims] 1. A dicing method for cutting a wafer on which semiconductor elements are formed into individual semiconductor chips while applying cutting water to a cutting blade, wherein the cutting water is oxidizing water for oxidizing a cut surface of the wafer. A dicing method comprising: 2. The dicing method according to claim 1, wherein the oxidized water contains hydrogen peroxide water or oxygen-dissolved water.