JPH07297161A - Cleaning method - Google Patents

Abstract

PURPOSE:To shorten the time required for cleaning by performing wet cleaning upon finishing dry cleaning thereby decreasing the number of cleaning baths in a cleaning equipment. CONSTITUTION:Prior to wet cleaning using cleaning baths 2, 3, 4, dry cleaning is performed using a dry cleaning equipment 1 in order to remove dusts larger than 100mum, especially an organic solvent. The dry cleaning equipment 1 removes dusts, principally organic compounds larger than 100mum, using clean air or gas. Ultrasonic cleaning is performed at the first cleaning bath 2 while supplying water in order to remove dusts larger than 10mum. Ultrasonic cleaning using an organic solvent is performed at the second cleaning bath 3 in order to remove fats and oils. Finish cleaning is performed using an organic solvent at the third cleaning bath 4. This method eliminates the need of wet cleaning for removing dusts larger than 100mum, especially organic solvents, using a detergent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method, and more particularly to a novel cleaning method capable of cleaning a solid-state image pickup device, a semiconductor wafer, etc. in a short time without using a large cleaning device.

[0002]

2. Description of the Related Art A solid-state image pickup device, particularly a solid-state image pickup device before being sealed with a sealing glass housed in a package made of ceramic or the like, has a defect that the presence of a minute foreign matter of only a few μm leads to a defect. Very careful cleaning was performed as shown in. The cleaning device used has seven cleaning tanks a to g as shown in FIG. First cleaning tank a
Is to remove chips and oil components, and ultrasonic cleaning is performed using a detergent. The second cleaning tank b removes dust of 100 μm or more, and ultrasonic cleaning is performed using a detergent as in the first cleaning tank a.

The third cleaning tank c is an object to be cleaned by cleaning in the first cleaning tank a and the second cleaning tank b (for example, a solid-state image pickup device before sealing with sealing glass) and a carrier containing the same. The detergent adhering to is washed away, and tap water is used as a washing liquid. The fourth cleaning tank d is for removing dust of 10 μm or more, and is subjected to ultrasonic cleaning using pure water. As a result, most of the fine dust contained in the water is removed, and 90% or more of the dust is removed. The fifth cleaning tank e has a dust of 1 μm or more,
In particular, it removes impurities such as fats and oils, and high frequency ultrasonic cleaning is performed using an organic solvent. The high frequency ultrasonic cleaning is performed to remove micron level dust. The sixth cleaning tank f is used for finish cleaning by overflow rinse using an organic solvent. The seventh cleaning tank g is for performing vapor drying using, for example, IPA (isopropyl alcohol), which makes the surface considerably clean, and the cleaning process is completed.

[0004]

By the way, in the above-mentioned conventional cleaning method, the number of cleaning tanks constituting the cleaning device is as large as seven, the cleaning device used for this purpose is large, and the time required for cleaning is large. There was a problem that it was long. Therefore, when the inventor of the present application investigated the factors inevitably increasing the number of cleaning tanks constituting the cleaning device,
I noticed that there is a factor that it is necessary to wash away the detergent afterwards in order to remove large dust at the beginning of the series of washing steps,
We sought to make it possible to reduce the number of washing tanks by performing another washing instead of washing with a detergent.

The present invention was born as a result of such a search, and provides a novel cleaning method capable of reducing the cleaning tank of the cleaning device used for cleaning and shortening the time required for cleaning. The purpose is to

[0006]

The cleaning method of the present invention is characterized in that dry cleaning is performed and then wet cleaning is performed.

[0007]

According to the cleaning method of the present invention, since the dry cleaning is performed before the wet cleaning, large dust can be removed by the dry cleaning. Therefore, there is no need to perform washing with a detergent as wet washing, and it is not necessary to wash away the detergent attached to the object to be washed and the carrier in which it is placed. Therefore, the number of cleaning tanks of the cleaning device used for cleaning can be reduced, and the time required for cleaning can be shortened.

[0008]

The cleaning method of the present invention will be described in detail below with reference to the illustrated embodiments. FIG. 1 shows one embodiment of the cleaning method of the present invention. In the drawings, reference numeral 1 is a dry cleaning device, which removes dust with clean air or gas. Mainly, organic substances of 100 μm or more are removed.

Reference numeral 2 denotes a first cleaning tank, which performs ultrasonic cleaning with pure water to mainly remove dust of 10 μm or more.
Reference numeral 3 is a second cleaning tank for performing ultrasonic cleaning with an organic solvent. As a result, oils and fats can be removed. Reference numeral 4 denotes a third cleaning device, which performs a final cleaning with an organic solvent.

No. 5 is for performing vapor drying by using IPA, whereby a considerably clean surface is obtained and the cleaning process is completed. In this cleaning method, before the wet cleaning in the cleaning tanks 2, 3 and 4, dry cleaning is performed by the dry cleaning device 1 to remove dust of 100 μm or more, particularly organic solvent.

Therefore, wet cleaning with a detergent to remove dust of 100 microns or more, particularly an organic solvent is not necessary. Further, it is not necessary to wash away the detergent used for such wet cleaning. Therefore, the cleaning tanks a, b, and c shown in FIG. 6 are not necessary, and the occupation area of the cleaning device can be reduced, and the wet cleaning by the cleaning tanks a, b, and c is performed once. It can be replaced with one dry wash.

Further, since there is no wet cleaning with a detergent, and therefore there is no carry-in of the detergent into the cleaning tank 2 by the object to be cleaned and its carrier, it is not necessary to wash the detergent with water. There is no need to remove dust, and the need for conventional cleaning with an organic solvent by high-frequency ultrasonic waves is reduced, and cleaning with an organic solvent by ordinary ultrasonic waves can replace it. The ordinary ultrasonic cleaning device and the high-frequency ultrasonic cleaning device have different device configurations, and the high-frequency ultrasonic cleaning device is more complicated, and the device price is considerably high. Therefore, the cost of the cleaning device used in the present cleaning method need not be high.

In the cleaning method of the present invention, the ultrasonic cleaning in the cleaning tank 3 is replaced by high-frequency ultrasonic cleaning instead of ordinary ultrasonic cleaning so that fine dust and oils and fats can be completely removed. Good. FIG. 2 shows such an embodiment. The present invention can be applied not only to cleaning the solid-state imaging device in a state before sealing with the sealing glass housed in a package such as ceramic but also to cleaning semiconductor wafers.

FIG. 3 is a vertical sectional view showing an example 1a of a dry cleaning apparatus used in the cleaning method shown in FIGS. Reference numeral 11 denotes a nozzle body, and the nozzle body 11 has a hollow portion 12 therein. An exhaust pipe 13 is connected to the nozzle body 11 so as to communicate with the hollow portion 12, and an opening 14 is provided at the center of the tip surface of the nozzle body 11.

Here, in the dry cleaning apparatus 1a,
An air inflow groove 15 is provided on the tip surface of the nozzle body 11 so as to connect the opening 14 formed substantially in the center thereof to the outside of the nozzle. That is, from each side of the rectangular opening 14 formed on the tip end surface of the nozzle body 11, elongated grooves outward, that is, air inflow grooves 15, 15, 15, 1,
5 (only two 15, 15 appear in the drawing) are formed, and the air inflow grooves 15, 15, 15, 15 make the opening 14 communicate with the outside of the nozzle. .

In the dry cleaning apparatus 1a, the tip surface of the nozzle body 11 and the opening 14 formed therein are:
The external dimensions of the package 21 to be processed, which accommodates the solid-state imaging device 23 and is not sealed yet, are set. That is, the outer dimension of the tip surface of the nozzle body 11 is set to be slightly larger than the opening dimension of the recessed portion 22 of the package 21, and the hollow portion 12 of the nozzle body 11 and the recessed portion 22 of the package 21 are approximately at the center of the tip surface. The opening 14 is formed so as to communicate with and.

Next, the operation of the dry cleaning device 1a will be described. First, as shown in FIG. 3, the opening of the recess 22 of the package 21 is closed by the tip surface of the nozzle body 11, and the hollow portion 12 of the nozzle body 11 and the recess 22 of the package 21 are communicated with each other through the opening 14.

Then, by driving a vacuum device (not shown), the air in the hollow portion 12 of the nozzle body 11 and the recess 22 of the package 22 is sucked from the exhaust pipe 13 with a predetermined vacuum pressure. Then, since the air inflow groove 15 is provided on the tip end surface of the nozzle body 11, when the air is sucked from the exhaust pipe 3, the tip of the nozzle body 11 passes through the air inflow groove 15 as shown by a dashed line in the figure. Outside air is taken into the hollow portion 12 from the portion.

When the outside air is taken in from the air inflow groove 15 in this way, the airflow speed on the article 23 to be cleaned is increased, and as a result, the article 23 to be cleaned and the package 2 are cleaned.
Dust (indicated by a black circle) is easily released from the surface of 1.
That is, since the airflow velocity on the object to be cleaned 23 is increased, a larger suction force acts on the dust in the package 21, and the dust can be reliably removed.

As described above, in the present dry cleaning apparatus, not only dust (shown by white circles) floating in the recess 12 of the package 11 but also dust attached to the surfaces of the package 21 and the object to be cleaned 23 can be removed. .

FIG. 4 shows another example of the dry cleaning apparatus. The dry cleaning apparatus 1b has a combination of an air nozzle 25 and a suction pipe 26 arranged on the front side and the back side of an object to be cleaned (for example, a semiconductor wafer) 23. The air nozzle 25 blows off dust on the object to be cleaned 23. The dust that has blown away is sucked through the suction pipe 26 to perform dry cleaning.

FIGS. 5A to 5C show still another example 1c of the dry cleaning apparatus, FIG. 5A being a plan view.
(B) is a perspective view and (C) is a cross-sectional view showing a main part. In the drawings, 31 is a carrier for a semiconductor wafer 37 is set, 32 is conveying portion for conveying the wafer 37 in the carrier 31, 33 is N ₂ gas-blowing portion, 34 the N ₂
It is a transfer unit that transfers the wafer 37 from the gas blow unit 33 to the carrier 35.

The N ₂ gas blowing part 33, as shown in FIG. 5 (C), a clean N ₂ from above and below the semiconductor wafer 37
The gas is blown to exhaust from the side, and the velocity of N ₂ gas blown from above is 1.5 m / se.
c, the speed of N ₂ gas sprayed from below is 1.5 / sec
The reason why the speed from the top is faster than from the bottom is to reliably prevent the dust on the back side from going to the front side and adhering to the surface of the semiconductor wafer 37.

Reference numerals 36, 36, 36 and 36 denote claws for fixing the semiconductor wafer 37.
The position of 7 is fixed, and dry cleaning is performed. Thus, there can be various types of dry cleaning devices. The work of the dry cleaning device 1c is automatically performed when a command is input by a keyboard and a command is given.

[0025]

The cleaning method of the present invention is characterized by performing dry cleaning and then wet cleaning. Therefore, according to the cleaning method of the present invention, since the dry cleaning is performed before the wet cleaning, large dust can be removed by the dry cleaning. Therefore, there is no need to perform washing with a detergent as wet washing, and it is not necessary to wash away the detergent attached to the object to be washed and the carrier in which it is placed. Therefore, the cleaning tank of the cleaning device used for cleaning can be reduced, and the time required for cleaning can be shortened.

[Brief description of drawings]

FIG. 1 is an explanatory view showing one embodiment of a cleaning method of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the cleaning method of the present invention.

FIG. 3 is a vertical sectional view showing an example of a dry cleaning apparatus.

FIG. 4 is an explanatory diagram showing another example of a dry cleaning device.

5A to 5C show still another example of the dry cleaning device, FIG. 5A is a plan view, and FIG. 5B is a perspective view.
(C) is a sectional view showing a main part.

FIG. 6 is an explanatory diagram showing a conventional example of a cleaning method.

[Explanation of symbols]

 1 Dry cleaning device 2 Wet cleaning tank

Claims (1)

[Claims] 1. A cleaning method comprising performing dry cleaning and then wet cleaning.