JPH0513396A - Cleaning method for semiconductor device - Google Patents

Abstract

PURPOSE:To remove completely foreign substances by a method wherein a hole or a groove formed in a semiconductor wafer is irradiated with ultrasonic waves, each having a horizontal component and a vertical component, and the foreign substances are discharged outside by the molecular motion of a liquid. CONSTITUTION:An ultrasonic oscillator 6 is mounted on the wall surface of a cleaning tank 4, in which a cleaning liquid 5 is put. The oscillator 6 is mounted in such a way that the surface of a semiconductor wafer 2 is irradiated with ultrasonic waves 7 at a prescribed angle. For example, the mounting wall surface of the tank 4 is slanted to mount the oscillator 6. The waves 7 respectively have a horizontal component 7a and a vertical component 7b to a trench hole 3 as seen from the surface of the wafer 2 having the trench hole 3. The component 7a makes the liquid 5 in the hole 3 vibrate in horizontal directions 8a to eliminate foreign substances in the hole 3. The component 7b makes the liquid 5 in the hole 3 vibrate in vertical directions 8b to keep foreign substances discharged on the surface of the wafer 2 away from the surface of the wafer 2. Thereby, residues of particles in the hole 3 and on the wafer surface are eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a semiconductor device, and more particularly to a method for cleaning a semiconductor device capable of removing foreign matter adhering to holes and grooves formed in a semiconductor wafer.

[0002]

2. Description of the Related Art Recently, as semiconductor devices, for example, semiconductor integrated circuits have been miniaturized, the structure of circuits formed on the surface of a semiconductor wafer has become complicated, and the surface of the semiconductor wafer has become severe. Therefore, as shown in FIG. 5, the foreign matter 1 remains in the vicinity of the opening of the trench hole 3 formed on the surface of the semiconductor wafer 2 and along the wall surface after the intermediate portion. Therefore, in each step of manufacturing a semiconductor integrated circuit, not only the foreign matter 1 on the wafer surface is removed, but also foreign matter in a rough area, for example, a trench hole having an aspect ratio of about several tens or a foreign matter in a groove is surely obtained. When the film is washed with a pure water rinse for 60 minutes and then self-dried,
As shown in (a), the particles adhering to the wafer surface are peeled off, but the foreign matter 1 remains at all. In addition, when washed with SC-1 for 5 minutes and rinsed with pure water for 5 minutes and then self-dried, as shown in FIG. 6B, the foreign matter 1 disappears on the surface of the semiconductor wafer 2, but inside the trench hole 3. Yes, it remains.

[0003]

However, the above-mentioned conventional method for cleaning a semiconductor device has a problem that there is no effective means for completely removing foreign matter in the trench hole, and the foreign matter remains at all. The present invention has been made in order to solve the above problems, and an object thereof is to remove foreign matters on the surface, holes and grooves of a semiconductor wafer by molecular movement of a cleaning liquid by ultrasonic waves.

[0004]

A method of cleaning a semiconductor device according to the present invention irradiates a hole or groove formed in a semiconductor wafer with ultrasonic waves having horizontal and vertical components to vibrate liquid molecules. To be washed.

[0005]

According to the present invention, the foreign matter existing on the surface of the semiconductor wafer, the hole and the groove is removed from the hole by the molecular motion of the cleaning liquid (similar in size to the foreign matter) with the aid of ultrasonic energy.
It can be completely removed to the outside after coming out from inside the groove.

[0006]

1 is a diagram showing an embodiment of a method for cleaning a semiconductor device according to the present invention. In particular, FIG. 1 (a) is a sectional side view thereof, and FIGS. 1 (b) and 1 (c) are It is a figure for demonstrating the washing | cleaning operation | movement in Fig.1 (a). In the figure, 4 is a cleaning tank containing a cleaning liquid 5, 6 is an ultrasonic oscillator which is attached to the wall surface of the cleaning tank 4 and outputs an ultrasonic wave 7. As an example, the ultrasonic wave 7 is the surface of the semiconductor wafer 2. This is a case where the ultrasonic oscillator 6 is attached so as to irradiate at a predetermined angle, and as an example, the ultrasonic oscillator 6 is attached by inclining the mounting wall surface of the cleaning tank 4.

Next, a method of cleaning the semiconductor device having the above structure, particularly an operation of cleaning the inside of the trench hole 3 to remove foreign matters will be described with reference to FIGS. 1 (b) and 1 (c). First, when viewed from the surface of the semiconductor wafer 2 having the trench hole 3, the ultrasonic wave 7 can be divided into a horizontal component 7a and a vertical component 7b with respect to the trench hole 3 as shown in FIG. Therefore, the horizontal component 7a of this ultrasonic wave 7
As shown in FIG. 1C, the cleaning liquid 5 in the trench hole 3 is
Is vibrated in the horizontal direction 8a to separate the foreign matter 1 in the trench 3 and discharge the foreign matter to the outside of the trench hole 3. on the other hand,
As shown in FIG. 1C, the vertical component 7b of the ultrasonic wave 7 vibrates the cleaning liquid 5 in the trench hole 3 in the vertical direction 8b to remove the foreign matter 1 discharged from the surface of the semiconductor wafer 2 from the surface of the semiconductor wafer 2. Acts to keep away.

By setting the attachment angle of the ultrasonic oscillator 6 to the semiconductor wafer 2 to about 20 to 70 degrees, the foreign matter 1 in the trench hole 3 can be efficiently peeled and discharged. In FIG. 7, it is a case of cleaning with (SC-1) + (MS) for 10 minutes, followed by cleaning with pure water rinse for 5 minutes and then self-drying, and no particles remain in the trench 3 and the surface of the semiconductor wafer.

2A and 2B are views showing another embodiment of the method for cleaning a semiconductor device according to the present invention. In particular, FIG. 2A is a sectional side view thereof, and FIGS. 2B and 2C are the same. Figure 2 (a)
FIG. 7 is a diagram for explaining the cleaning operation in FIG. In the figure. Reference numerals 9a to 9d are first ultrasonic oscillators that output ultrasonic waves 10 in the horizontal direction to the trench holes 3, and 11 are second ultrasonic oscillators that output ultrasonic waves 12 in the vertical direction to the trench holes 3. Needless to say, the operation of peeling and removing the foreign matter adhered to the surface of the semiconductor wafer 2 and the foreign matter 1 in the trench hole 3 is the same as the operation of FIG.

Next, the frequency (MHZ) and power (W / cm ² ) of ultrasonic waves for removing the foreign matter 1 in the trench hole 3 are removed.
The relationship will be described with reference to FIGS. 3 and 4. First, in order to remove the foreign matter 1 in the trench hole 3, (A)
In order to transfer energy to the molecular flow 13 of the cleaning liquid 5 in the trench hole 3, ultrasonic waves having a vibration width smaller than the diameter of the trench hole 3 are used. (B) The foreign substance 1 in the trench hole 3 is vibrated by the molecular flow 13 of the cleaning liquid 5. In order to discharge the foreign matter 1 out of the trench hole 3 by accelerating the stirring of the cleaning liquid 5 by the peeling and the molecular flow 13 of the cleaning liquid 5 in the trench hole 3, the surface of the semiconductor wafer 2 (vertical hole 3 (C) and the ultrasonic wave having a vibration width similar to that of the foreign matter 1 (C) The foreign matter 1 discharged to the surface of the semiconductor wafer 2
Since the stirring of the cleaning liquid 5 on the surface of the semiconductor wafer 2 is accelerated by the molecular flow 13 of the cleaning liquid 5 and distanced from the surface of the semiconductor wafer 2, it is horizontal (vertical to the trench hole 3) to the surface of the semiconductor wafer 2 and This is possible with ultrasonic waves having a vibration width similar to that of the foreign matter 1. Therefore, the relationship between the acoustic power (I: W / cm ² ) of ultrasonic waves, the frequency (f), and the molecular vibration width (A: cm) of the cleaning liquid 5 can be shown below.

[0011] In the case of ^{I = PC (2πfA) 2/} 2 However, P is a density (g / cm ³⁾ of the washing solution (5) (in the case of water 1) C is the sound velocity (cm / S) (water 1. 5 × 10 ⁵ (cm /
S))

0.06 μ in the trench hole 3 with a width of 1 μm
In order to remove foreign matter 1 efficiently and obtain a liquid molecule vibration width of 0.06 μm, the frequency is 800K from the above formula.
Hz and sound power of 7.5 W / cm ² are required. FIG. 4 shows the relationship between the frequency and the acoustic power when the vibration widths of 0.01 μm, 0.06 μm and 0.5 μm are obtained.
In addition, foreign matter (0.5 μm) in the trench hole (3) having a width of 1 μm
μm to 0.01 μm) to remove 100 KHz to 1
It is necessary to apply an ultrasonic wave having a vertical component and a horizontal component to the wafer surface with a frequency of 0 MHz and acoustic energy of 0.01 to 4,000 W / cm ² to the trench hole 3.

[0013]

As described above in detail, according to the method of cleaning a semiconductor device of the present invention, the foreign matter adhering to the holes and the grooves formed in the semiconductor wafer and the surface thereof is removed by ultrasonic waves and liquid flow. There is an effect that it can be peeled off by the kinetic energy of and can be completely discharged to the outside.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a method for cleaning a semiconductor device according to the present invention.

FIG. 2 is a diagram showing another embodiment of the semiconductor device cleaning method according to the present invention.

FIG. 3 is a diagram showing a method of removing foreign matter in a trench hole of a semiconductor wafer.

FIG. 4 is a diagram showing the relationship between the molecular vibration width of liquid, ultrasonic acoustic energy, and frequency.

FIG. 5 is a diagram showing a standard contamination sample of foreign matter in a trench hole.

FIG. 6 is a diagram showing a case where the inside of the trench hole and the wafer surface are cleaned by a conventional method for cleaning a semiconductor device.

FIG. 7 is a diagram showing a case where the inside of the trench hole and the wafer surface are cleaned by the method for cleaning a semiconductor device according to the present invention.

[Explanation of symbols]

 1 Foreign Material 2 Semiconductor Wafer 3 Trench Hole 4 Cleaning Tank 5 Cleaning Solution 6 Ultrasonic Oscillator 7 Ultrasonic Waves 8a, 8b Vibration Direction of Cleaning Solution 10, 12 Ultrasonic Waves 9a-9b, 11 Ultrasonic Oscillator

Claims (1)

Claim: What is claimed is: 1. A semiconductor characterized in that a hole or groove formed in a semiconductor wafer is irradiated with ultrasonic waves having horizontal and vertical components to vibrate liquid molecules for cleaning. How to clean the equipment.