JPS63228733A - Cutting method for semiconductor substrate - Google Patents

Abstract

PURPOSE:To eliminate swarf by a simple method and improve the yield, by spreading a soluble organic film on the whole surface before a semiconductor substrate is cut into chips, gathering the swarf at the time of cutting on the organic film, rinsing it with pure water, and washing it away together with the organic film. CONSTITUTION:A suluble organic film 2 is spread on a semiconductor substrate 1, which is stuck on a adhesive sheet 3, and is cut along a cutting line 4 by a blade rotating at a high speed. In this process, pure water is sprinkled on the blade to restrain the generated heat by the friction with the substrate, and a film 2 attaching to the blade is washed away. Accordingly, the swarf 5 generated by cutting is left on the film 2 except the vicinity of a region of the line 4. By making the pure water flow, the film 2 is solved and washed away, so that the swarf 5 on the film 2 can be eliminated together with the film 2. Thereby, the swarf is eliminated by a simple method, the yield of a manufacturing process is improved, and the reliability is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of cutting a semiconductor substrate in order to divide the substrate into chips having specific functions.

BACKGROUND OF THE INVENTION As the performance of semiconductor integrated circuits increases and their prices decrease, the effects of the assembly process on product costs and performance2 yields cannot be ignored. The assembly process flowchart is generally the second
As shown in the figure, there is a veretizing process in which the wafer is divided into chips, a process in which the chips are fixed to the tabs on the IJ dome, a process in which the electrodes on the chips and the lead frame are wired, and a process in which the wafer is sealed with resin. Consists of. FIG. 3 shows a dicing process that is currently in practical use. After the semiconductor substrate 1 is attached to the adhesive sheet 3, a cut is made along the cutting line 4 of the chip 6 using a thin disk (blade) rotating at high speed.

Half cut or semi-full cut depending on the depth of cut.

There are 3 full cut modes. A half cut is a cut to about half the thickness of the substrate, and breaking is required to divide it into chips 6. The bottom half will be cleaved, and the sheet will need to be stretched to attach the patch after braking.

Semi-full cutting does not require any special braking or stretching because cracks will form in the uncut portion during dicing. Full cut cuts down to adhesive sheet 3 and completely divides the chip. In either case, chips 6 are generated, and a method is used in which pure water is applied to both cool the blade and remove the chips 5 mentioned above.Especially after cutting, high-pressure pure water is used to remove chips attached to the substrate metal. is applied to the entire surface of the board.

Problems to be Solved by the Invention Chips generated during cutting of a semiconductor substrate are mostly substrate scraps, and sometimes are components of the blade. Large chips are washed away by pure water for cooling purposes, which prevents the sharpness of the blade from deteriorating due to heat generation caused by friction between the blade and the substrate. However, countless chips ranging in size from submicrons to several microns are not washed away, and most of them are left behind on the substrate surface. On the other hand, the surface of the substrate is usually covered with an oxide film, nitride film, or polymer film such as polyimide called a passivation film, except for the pad portion, that is, the portion where wire bonding is performed. Therefore, the aforementioned chips remain as residue on the passivation film or on the pad portion, that is, the aluminum metal portion. Usually, in order to remove them, a method is used in which a large amount of pressure is applied to the pure water and they are washed away together with the pure water. However, the adhesion of the chips is very strong and will only flow with high-pressure pure water of 100 bonds/square inch or more. At this level of high voltage, for example, in the case of a solid-state image sensor using a charge transfer element, a negative phenomenon such as an increase in white spot defects is observed, and it also has negative effects such as dielectric breakdown on LSI chips, which are becoming smaller and smaller. affect Therefore, in current assembly processes, tiny chips remain on most chips. These small chips have the following problems.

(a) Chips on the pad reduce the bonding force between the wire and the pad electrode during the next process of wire bonding, and cause bonding defects, leaving doubts about long-term reliability.

(b) Chips on the passivation film are the same as the semiconductor substrate during the sealing process, especially in plastic molding, so the chips enter the passivation film during molding and deteriorate the passivation characteristics, resulting in poor reliability. occurs.

The present invention has been made in view of the above-mentioned problems, and it allows cutting chips to adhere to a different type of membrane, and even by immersion in pure water,
It is an object of the present invention to provide a method for cutting a semiconductor substrate that can be easily removed.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention employs a method in which a water-soluble organic film is applied before cutting the semiconductor substrate, and after cutting it is washed with pure water. .

Effects According to the present invention, with the above-described configuration, cutting chips are scattered on the water-soluble organic film, and all of the cutting chips can be removed together with the water-soluble organic film by washing with pure water in the subsequent step.

Embodiment FIG. 1 schematically shows a dicing process according to an embodiment of the present invention. First, a water-soluble organic film 2 is applied onto a semiconductor substrate 1 . Polysaccharides are used as water-soluble organic films.

Using proteins, polyvinylpyrrolidone, polyvinyl alcohol, etc., and dialdehyde starch and dichromate to adjust the dissolution rate in water.

It may be composed of a diazide compound, an azide compound, an aldehyde compound, etc., and water. As a coating method, it is preferable to apply vacuum suction to the semiconductor substrate 1 to deposit an appropriate amount of the water-soluble organic film 2 thereon, and then rotate the substrate at high speed to stretch it thinly. For example, if the semiconductor substrate has a diameter of about 3 inches, by using a solution of about 1000 and spinning at 500 to 5000 revolutions/paper,
It can be applied to a thickness of about 1 to 5 μm. Of course, there is nothing wrong with applying it in the form of a spray.

However, in order to prevent dust from entering the organic film itself and having any adverse effect on the semiconductor substrate, the content of metal ions should be kept below 1 ppm in all cases, and a filter of at least 0.2 μm should be filtered before applying the solution. Filter it with
It is better to prevent water residue from forming in the subsequent process.

Next, the semiconductor substrate 1 is attached to the adhesive sheet 3.

Thereafter, the semiconductor substrate 1 is cut by cutting along the cutting line 4 with a blade rotating at high speed. The blade is usually sprayed with pure water to suppress the generation of heat due to friction with the semiconductor substrate. This also prevents the water-soluble organic film 2 from adhering to the blade and impairing its cutting quality. In other words, the attached organic film is washed away with pure water. In this way, all the chips 5 generated by cutting remain on the water-soluble organic film 2 except in the vicinity of the cutting line 4 region. After that, by running pure water to melt and wash away the water-soluble organic film 2, it becomes possible to lift-on and remove all the chips on the film together with the film, resulting in a good chip 6 as shown in Figure d. Can be divided.

Effects of the Invention As is clear from the above explanation, the present invention is capable of collecting cutting chips on the organic film by applying a water-soluble organic film to the entire surface of the semiconductor substrate before cutting it into chips. This has the effect that the chips are completely removed together with the water-soluble organic film by washing with pure water. Furthermore, the organic film can be removed by simple rinsing with running water, and there is no need for high-pressure pure water to blow away chips as in the conventional method. In this way, since chips can be completely removed in a very simple manner, it is possible to improve the yield and reliability of the assembly process.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a process according to an embodiment of the present invention, FIG. 2 is a 70-chart diagram of a normal assembly process, and FIG. 3 is a diagram showing a conventional cutting process. 1... Semiconductor substrate, 2... Water-soluble organic film, 3... Adhesive sheet, 4... Cutting line, 6... Chips, 6 ...chip. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Diagram cutting line diagram 2

Claims (1)

[Claims] a step of applying a water-soluble organic film to one main surface of a semiconductor substrate on which a semiconductor device having a specific function is formed; a step of cutting the semiconductor substrate along the cutting line with a thin disk rotating at high speed; A method for cutting a semiconductor substrate, comprising the step of washing the cut semiconductor substrate with pure water.