JPH0786221A - Dust removal device for semiconductor substrates - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a dust removing device for removing dust on a semiconductor substrate having a polyimide protective film formed on its surface without damaging the surface film. [Structure] Ionized air generated by the static eliminator 1 is discharged from between the bristles of the cleaning brush 2.
As a result, the charge of the polyimide protective film is alleviated and the adhesive force of the dust is reduced, so that the dust can be easily removed without damaging the protective film with the wiping bristles 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate dust removing apparatus, and can be used in the field of cleaning technology for semiconductor manufacturing processes.

[0002]

2. Description of the Related Art In the manufacturing process of wafers and semiconductor devices, countermeasures against electrostatic damage are important. As a countermeasure, not only wafers and semiconductor devices,
It is necessary to neutralize all the equipment and equipment around it. There are two types of electrostatic damage: electrostatic breakdown and dust adsorption.
There is one.

On the other hand, in recent devices, a polyimide film is often applied as a surface protective film after forming an element on a silicon substrate. As described above, the reason why polyimide is used is heat resistance, electrical characteristics,
This is because they are extremely excellent in mechanical strength, chemical resistance, and dimensional stability.

However, since the semiconductor substrate coated with the polyimide protective film is easily electrically charged, dust adhesion is unavoidable. Therefore, conventionally, a method of removing dust by using a cleaning brush or an N ₂ gun that blows nitrogen (N ₂ ) gas has been attempted.

[0005]

However, in the former method using the cleaning brush, since it is necessary to externally apply a force greater than the electrostatic attraction to the polyimide film surface to attract dust, the polyimide film surface may be damaged. ,
On the contrary, there is a problem that dust is embedded in the surface of the polyimide film.

Further, in the latter method using the N ₂ gun,
When N ₂ molecules collide with the surface of the polyimide film, the amount of charge on the surface of the polyimide film is further increased, and there is a problem that dust is more likely to be attached.

The problem to be solved by the present invention is to take any means to obtain a dust removing device for a semiconductor substrate, which can surely remove dust without damaging the polyimide film on the semiconductor substrate. There is a point.

[0008]

Therefore, the invention according to claim 1 of the present application is an electrostatic elimination device for generating an ionized gas in an apparatus for removing dust adhering to a semiconductor substrate having a polyimide protective film formed thereon. A flexible cleaning brush is provided, and the ionized gas generated in the static eliminator is discharged from the cleaning brush as a solution means. Further, the invention according to claim 2 is characterized in that the ionized gas is discharged through the bristles of the cleaning brush.

[0009]

In the invention described in claim 1 of this application, the ionized gas generated from the static eliminator is discharged from the cleaning brush to alleviate the charge on the surface of the polyimide protective film formed on the semiconductor substrate. In addition, the cleaning brush makes it possible to wipe off the dust having a weak adsorption force without damaging the surface of the polyimide protective film whose charge is alleviated with the soft bristles.

Further, as in the second aspect of the present invention, by discharging the ionized gas from the bristles, it is possible to uniformly spray the ionized gas onto the surface of the polyimide protective film with which the cleaning brush contacts. Become.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of a semiconductor substrate dust removing apparatus according to the present invention will be described below with reference to the embodiments shown in the drawings.

Prior to the description of this embodiment, a method of forming a polyimide protective film on a silicon wafer will be described. First, after forming elements and the like on a silicon wafer, a polyamic acid (which becomes polyimide after firing) is spin-coated on the wafer. The film thickness of the polyamic acid at this time is, for example, several μm to 1
It is 0 μm. Next, the solvent is volatilized at a temperature near the boiling point of the solvent contained in the polyamic acid, and then heat treatment is performed to imidize. The temperature at which the solvent is volatilized varies depending on the solvent, but in the case of NMP (normal 2 methylpyrrolidone) which is generally used, 200 to 250 ° C., and the imidation baking temperature for heat treatment is preferably about 300 to 400 ° C. . Further, it is better to prevent the oxidation of the polyimide by performing the imidization firing in a nitrogen atmosphere. It is considered that the charging of the polyimide is caused by the friction between the nitrogen gas dried during the imidization firing and the polyimide surface. It has been confirmed that it is already charged at least immediately after firing. As a result of measuring the electric potential corresponding to this amount of charged electric charge with a measuring instrument, it was +1500 volts. Adhesion of suspended particles (dust) to the surface of this charged wafer (polyimide protective film) is generally well known. In addition, the foreign matter once attached may have a soft polyimide surface, and in the case of a hard foreign matter, it may be pressed during the back surface grinding in the next step and embedded in the polyimide protective film.
As described above, since the foreign matter attached to the polyimide is electrochemically or physically adsorbed, it is extremely strong and difficult to remove. Therefore, in order to remove the foreign matter, the present embodiment is a dust removing device focusing on these two actions.

The structure of the semiconductor substrate dust removing apparatus according to this embodiment will be described below.

FIG. 1 is a perspective view showing the entire dust removing device of this embodiment. This dust removing device includes an electrostatic removing device 1 for generating an ionized gas and a cleaning brush 2.
It is composed of and. The static eliminator 1 has a built-in ionizer, for example, as shown in the explanatory view of FIG. 2, for ionizing air. This ionizer is
As shown in the figure, the electrodes 3 forming a row and the discharge counter electrodes 4 forming a row adjacent to the row of the electrodes 3 are alternately arranged, and the electrodes in the row direction are connected by the electrode rods 5. The electrode rod 5 is connected to a high voltage AC power source 6. Reference numeral 7 in the figure indicates a low-voltage DC power supply 7. Discharge is generated by such electrodes, and air is blown to the electrode side by the fan 8 shown in the figure to generate ionized air (gas).
In this example, the ionization device having the above-mentioned configuration was used.
Other various ionization devices can be applied.

Ionized air generated by the static electricity removing device 1 is introduced into the cleaning brush 2 through a resin tube 9 as shown in FIG. This cleaning brush 2 has a hollow grip 10
And a flexible wiping bristle 11 planted on the tip surface of the grip 10. Grip 10 is switch 1
2 is a mechanism that can open and close the ionized air supply passage. Also, the wiping hair 11 at the tip of the grip 10
As shown in FIG. 3, a large number of wiping bristles 11 are implanted at substantially equal intervals, and blow holes 13 are formed in the grip end faces at the roots between the wiping bristles 11. As shown in FIG. 4, when the switch 12 is pressed, the ionized air supply passage is opened, and the ionized air is discharged from the air blow hole 13. FIG. 4 shows a polyimide protective film 15
Is a state in which the wafer (semiconductor substrate) W formed on the surface is being cleaned. In this embodiment, the ionized air is set to be negatively (−) in order to alleviate or neutralize the charge of the positively (+) charged polyimide protective film 15.

FIG. 5A shows a state in which dust 16 is attached on the polyimide protective film 15 which is positively charged. In this state, since the charge amount is large as described above, the dust cannot be removed only by physical cleaning with the cleaning brush. Therefore,
By operating the dust removing device of the present embodiment and blowing the ionized air (−), as shown in FIG. 5B, the positive charge on the surface of the polyimide protective film 15 is relaxed, and the adsorption force of the dust 16 is absorbed. Becomes smaller, and as shown in FIG. 5C, it can be easily removed by the wiping bristles 11.

Although the embodiment has been described above, the present invention is not limited to this, and various design changes are possible accompanying the gist of the structure of the present invention.

For example, the static eliminator 1 may be provided with a controller for adjusting the amount of ionization, and the switch mechanism of the cleaning brush 2 can be modified in various ways.

Further, in the above-mentioned embodiment, the blow holes 13 for the ionized air are provided between the wiping bristles 11, but the ionized air may be discharged so as to surround the entire wiping bristles 11.

[0020]

As is apparent from the above description, according to the first and second aspects of the present invention, foreign matter (dust) attached to the polyimide protective film on the surface of the semiconductor substrate is damaged by the polyimide protective film. There is an effect that can be surely removed.

Therefore, it is possible to provide a product in which the surface of a normal device or an optical device is free from scratches and foreign matters.

[Brief description of drawings]

FIG. 1 is a perspective view of a dust removing device according to a seventh embodiment of the present invention.

FIG. 2 is a schematic explanatory view of an ionization device.

FIG. 3 is a cross-sectional view of a main part of a cleaning brush.

FIG. 4 is an explanatory view showing a usage state of a cleaning brush.

5A to 5C are cross-sectional views showing a process of removing dust on the polyimide protective film.

[Explanation of symbols]

 1 ... Electrostatic eliminator 2 ... Cleaning brush 11 ... Wiping bristles 15 ... Polyimide protective film 16 ... Dust W ... Wafer

Claims (2)

[Claims] 1. A device for removing dust adhering to a semiconductor substrate having a polyimide protective film, comprising an electrostatic eliminator for generating an ionized gas and a flexible cleaning brush. A dust removing device for a semiconductor substrate, wherein the ionized gas is discharged from the cleaning brush. 2. The dust removing device for a semiconductor substrate according to claim 1, wherein the ionized gas is discharged through the gaps between the bristles of the cleaning brush.