JPH03227556A - Dicing method - Google Patents

Abstract

PURPOSE:To prevent charge and contamination be using a salt of a compound of acid radical and ammonia acid radical as a solute of aqueous solution used for cooling dicing blade or cooling a cut section of a wafer. CONSTITUTION:A salt of a compound of acid radical and ammonia acid radical is used as a solute to be mixed into water 4 and 4' for cooling a dicing blade 1 or cooling a cut section of a wafer 2. The salt used herein can make aqueous solution 4 and 4' substantially neutral and is a solute capable of providing a high electric conductance which does not produce static electricity during ejection and does not contaminate wafers. This construction makes it possible to protect an Al exposed part on the wafer from damage, increase electric conductance to a satisfactory extent, prevent charge, inhibit electrostatic breakdown, and prevent the contamination of wafers produced by alkali metal ions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] This invention relates to a dicing method for cutting out individual semiconductor chips from a semiconductor wafer.

The purpose of this invention is to obtain a method that can prevent water from becoming electrified by keeping water used for cooling/cleaning almost neutral and increasing its electrical conductivity, and is free from contamination by alkali metal ions.

A salt made of a compound of an acid group and an ammonia base is used as a solute in an aqueous solution used for cooling a dicing blade or cleaning a cut portion of a wafer.

[Industrial Application Field] The present invention relates to a dicing method for cutting a semiconductor wafer into individual semiconductor chips.

When a wafer is cut using a dicing blade after the wafer process is completed, cooling water and cleaning water are sprayed from a nozzle onto the cut portion to dissipate heat and remove chips (see Figure 1). At this time, the water discharged from the nozzle becomes electrically charged and causes electrostatic damage to circuit elements formed on the wafer, so various countermeasures have been taken, and the present invention can be applied to this prevention.

[Conventional technology]

The conventional antistatic method uses water in which carbon dioxide gas (Cot) is dissolved in cooling water or cleaning water that is sprayed onto the dicing blade to increase electrical conductivity and prevent static electricity.

However, when CO2 is mixed in, water becomes acidic.

It was not possible to freely specify the amount of CO2 mixed in because it would damage the aluminum film exposed on the wafer.

[Problems to be Solved by the Invention] Therefore, by increasing the amount of CO□ mixed in, it is not possible to sufficiently prevent static electricity, resulting in the problem of static electricity being injected into circuit elements on the wafer.

As a countermeasure for this, there is a technique disclosed in Japanese Unexamined Patent Publication No. 63-28608.

This method involves mixing a surfactant into carbonated water to increase the electrical conductivity of the water and prevent it from becoming electrostatically charged.

The surfactant may be any alkaline surfactant that can adjust the pH of carbonated water to approximately neutral. Examples include alkali metal salts of fatty acids.

In this case, since a surfactant is used, the permeability of the surfactant is good, making it difficult to clean and remove the surfactant, and there is also a concern that the wafer may be contaminated by alkali metal ions and the like.

The present invention provides a dicing method that can keep the water used for cooling/cleaning almost neutral, sufficiently increase the electrical conductivity of the water, and prevent charging, and without worrying about contamination with alkali metal ions. The purpose is to

[Means to solve the problem]

The above problems are achieved by a dicing method that uses a salt made of a compound of an acid group and an ammonia base as a solute in an aqueous solution used for cooling a dicing blade or cleaning a cut portion of a wafer.

[Effect]

The present invention uses a salt consisting of a compound of an acid group and an ammonia base as a solute mixed into the water used for cooling the dicing blade or cleaning the cut portion of the wafer.This salt makes the aqueous solution almost neutral and eliminates static electricity when ejected. It is a solute that has solubility that high electrical conductivity can be obtained to the extent that it does not occur, and also takes advantage of the fact that there is no risk of contaminating the wafer.

Also, this salt does not contain alkali metal salts.

There is no fear of wafer contamination due to this.

Here, if the acid group is a weak acid group such as a carbonate group.

There is less danger when salt decomposes and produces acid due to electrolysis or other causes.

In addition, using ammonia base makes it easy to adjust the pH.
This is because the solubility of the salt is high, the difference in concentration of the aqueous solution is small, and the flow rate can be easily controlled.

〔Example〕

FIG. 1 is a perspective view illustrating an embodiment of the present invention.

In the figure, a dicing blade 1 has fine diamond grains fixed around it with a binder metal, rotates as shown by the arrow, and then moves relatively over a wafer 2 to cut the wafer 2 into dice.

At this time, an aqueous solution 4 prepared by dissolving a salt consisting of a compound of an acid group and an ammonia base, such as ammonium carbonate (Nu41zc(h) to increase the electrical conductivity, is sprayed from a nozzle 3 onto the cut portion as cooling water.

The nozzle 3' uses the same or different aqueous solution 4' as cleaning water.
Spray at high pressure onto the cut area.

Here, the saturation concentration of (NH4)zcOi is 100g
/100 ml, and within this range, this salt can be considered to be almost entirely dissociated, with about 10 mol/l of charged bodies present, which means that 1 mol/l of KCI is about 1
As can be seen from the fact that it has a specific resistance of 0 Ωcm (quoted from the science calendar), the ~IM Ωcm that was conventionally obtained with COz
This is a sufficiently low value compared to the specific resistance of .

From this, it can be seen that the salt of the example has an electrical conductivity that is orders of magnitude higher than that of the conventional example, and is more effective in preventing static electricity.

In the examples, (NH4)2CO3 was used as a salt consisting of a compound of an inorganic acid and an ammonia base, but the same effect can be obtained by using a compound of a carboxylic acid with an ammonia group, such as CHZCOONH, instead. be.

〔Effect of the invention〕

As explained above, according to the present invention, the pH of the water used for cooling/cleaning is kept almost neutral, and the electrical conductivity is sufficiently increased to charge the exposed AI parts such as pads on the wafer without damaging them. A dicing method has been obtained which can suppress electrostatic damage to circuit elements by preventing this, and which does not have to worry about contamination of the wafer with alkali metal ions or the like.

[Brief explanation of drawings]

The first section is a perspective view illustrating an embodiment of the present invention. In fig. 1 is a dicing blade. 2 is a wafer. 3.3' is the nozzle 4.4' is an aqueous solution [Kinmine Fumap to be embroidered in one row] Rod 2 1 Kasumi

Claims (1)

[Claims] A dicing method characterized in that a salt consisting of a compound of an acid group and an ammonia base is used as a solute in an aqueous solution used for cooling a dicing blade or cleaning a cut portion of a wafer.