JPH0344927A - Cleaning method for semiconductor substrate and cleaning apparatus used therefor - Google Patents

Abstract

PURPOSE:To discharge remaining gas of a recess of a substrate to sufficiently distribute cleanser and to clean the substrate in a desired state by reducing a treating tank containing the substrate in a reduced pressure state, immersing the substrate with the supplied cleanser, and applying an ultrasonic vibration thereto. CONSTITUTION:A wafer 4 is placed on a wafer supporting base 11 of a treating tank 10, the tank 10 is pressure-reduced, and cleanser 3 is supplied from a cleanser supply tube 14 until the part of a vibrator 13 is immersed. Then, when the tank 10 is returned therein to the atmospheric pressure, the cleanser 3 is immersed into the trench of a substrate. Here, when an ultrasonic vibration is applied to a wafer 4 through the cleanser 3 by the vibrator 13, gas remaining in the bottom of the trench is bubbled to be discharged, and the cleanser 3 is sufficiently distributed to the whole trench face. Thus, the wafer 4 can be desirably cleaned to improve its quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor substrate cleaning method for cleaning a semiconductor substrate in which a recessed portion is formed, and a cleaning apparatus used therefor.

[Conventional technology]

In recent years, as semicircular integrated circuits have become highly integrated and miniaturized, circuit patterns formed on semiconductor substrates (hereinafter simply referred to as wafers) have also become miniaturized and their structures have become more complex. For this reason, a technique has been adopted in which an fc recess is formed on the UNO and an element is formed in that portion.

Furthermore, as the integration and miniaturization progress, foreign matter adhering to the wafer, which has not been a problem in the past, has become a major problem due to its characteristics.

Therefore, they must be reliably removed by a cleaning process. A cleaning process is performed in a process after engraving when forming the recesses, or in a process to remove oxides formed on the wafer.

FIG. 4 is a diagram showing a schematic configuration of a cleaning device that performs this type of conventional cleaning process. In the figure, (1) is the cleaning tank in which cleaning is performed, (3) is the cleaning liquid supplied in the cleaning tank (1), (4) is the wafer that is immersed in the cleaning liquid (3), and 01) is the cleaning tank It is a wafer support stand provided in (1) and on which the wafer (4) is placed.

Next, a cleaning method using the cleaning apparatus configured in this manner will be explained. First, the cleaning liquid (3) is supplied into the cleaning tank C1) until the cleaning tank (1) reaches a predetermined height.
3). Thereafter, the wafer (4) is transferred into the cleaning tank (1) and placed on a wafer support table 0υ.The wafer (4) is thus immersed in the cleaning liquid (3) to be processed. At this time, the cleaning liquid (3) is usually circulated. The wafer (4) is cleaned in this manner, and as shown in FIG. 5, a trench (5), which is a recess, is formed in the wafer (4). This trench (
5) is 1. For example, the planar dimensions of the opening are 1 μm x 1 μm,
The depth dimension is approximately 5 μm.

It is necessary to clean not only the main surface of the wafer (4) but also the inside of the trench (5).

By the way, in addition to the above-mentioned cleaning method using circulation, wafers (
As the cleaning method of 4), in order to further increase the cleaning efficiency,
Cleaning methods have also been used in which ultrasonic waves are applied to the cleaning liquid (3) and the cleaning liquid (4), or the cleaning liquid (3) is pressurized. Furthermore, the wafer (4) is placed on the wafer support stand 01).
There is also a method of cleaning the wafer (4) by placing the wafer thereon, reducing the pressure in the cleaning tank (1), and supplying the cleaning liquid (3) in that state.

[Problem to be solved by the invention]

The conventional cleaning method is as described above, and the inside of the fine trench (5), in which the planar dimension of the opening formed on the wafer (4) is lμrn×1 μm and the depth dimension is 5 μm, is not completely cleaned. Met.

That is, as shown in FIG. 5, even if the cleaning liquid (3) is supplied to the wafer (4) on which the trenches (5) are formed, the gas (6) remains in the trenches (5), and the cleaning liquid (3)
However, the entire inside of the trench (5) was completely destroyed.

This is because the opening width of the trench (5) is extremely small, so the surface tension of the cleaning liquid (3) is reduced, causing the trench (5) to have a very small opening width.
5) This is because it is difficult to replace the residual gas (6) in the trench (5) with the cleaning liquid (3) using cleaning methods such as ultrasonic, pressurization, and depressurization methods. . For this reason, in conventional cleaning methods, the bottom of the trench (5) is not cleaned, and the foreign substances cannot be completely removed, resulting in a problem in which the foreign substances remain and the reliability is impaired. There was a point.

This invention was made in order to solve the above-mentioned problems, and it is possible to improve the quality of the wafer by spreading the cleaning liquid into the recesses formed on the wafer, thereby improving the quality of the wafer. The purpose of the present invention is to obtain a cleaning method and a cleaning device used therefor.

[Means to solve the problem]

A method for cleaning a semiconductor substrate according to the present invention includes reducing the pressure in a processing tank in which a substrate is housed, supplying a cleaning liquid into the processing tank, and immersing the substrate in which a recess is formed in the cleaning liquid. Cleaning is performed by adding ultrasonic vibration treatment to these to discharge gas remaining in the recesses.

Further, the semiconductor substrate cleaning apparatus according to the present invention includes: a sealable processing tank in which a substrate is to be housed; a cleaning liquid supply means for supplying a cleaning liquid into the processing tank; The apparatus is equipped with ultrasonic generation means for applying ultrasonic vibrations to the processing tank, and depressurization and pressurization means for adjusting the inside of the processing tank to a depressurized or pressurized state.

[Effect]

In this invention, the processing tank is depressurized and pressurized by the means l,
By supplying the cleaning liquid from the cleaning liquid supply means under reduced pressure, the cleaning liquid is directed to the vicinity of the bottom of the recess formed on the substrate. Furthermore, in this state, the ultrasonic generation means is operated to apply ultrasonic treatment to the substrate through the cleaning liquid, so that the gas remaining at the bottom of the recess becomes bubbles and fills a predetermined space in the cleaning liquid or in the processing tank. The cleaning liquid is then discharged and spread over the entire surface of the recess.

In this way, the inside of the recess can be cleaned to a desired state with the cleaning liquid.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a diagram showing a schematic structure of a cleaning device according to an embodiment of the present invention. In the figure, H is the cleaning tank and 0υ is the cleaning tank C.
1f), a wafer support stand provided at the bottom of the cleaning tank OG, 04 a loading/unloading door that can be opened and closed at the side of the cleaning tank OG and formed in a watertight manner, and 03 a cleaning tank α0 facing the wafer support stand Qυ.
This is an ultrasonic transducer (hereinafter referred to as a transducer) provided on the upper part of the transducer. α force is a cleaning liquid supply pipe whose tip is inserted from the top of the cleaning tank Ql, and 00 is 4! of cleaning liquid supply pipe α4! , the pulp provided in the channel, and the tip part near a are the depressurization and pressurization parts inserted from the upper part of the cleaning tank (11) and facing the cleaning liquid supply pipes C1, 4+. α force is the cleaning tank The drainage pipe provided at the bottom of αO is the drainage pulp provided in the drainage pipe α force path.

Next, the wafer (
4) The method of cleaning will be explained.

First, the loading/unloading door 04 is opened lζ, the wafer (4) is transferred into the processing tank 0, and the wafer (4) is placed on the wafer support stand 0υ.
Place. A trench (5) is formed in this wafer (4), and on the wafer helmet holder aυ, the trench (5) is
) with the main surface side facing up (2)
) is placed. After opening the loading/unloading door a, operate the depressurizing unit αG to reduce the pressure inside the processing tank (II) to a predetermined pressure.At this time, the pulp (to) and drain valves are closed. After this, the pulp is opened and the cleaning liquid (3) 1, for example, pure water, is poured into the processing tank Q from the cleaning liquid supply pipe 04.
Supply within l. As shown in FIG. 2, this cleaning liquid (3) is supplied to such an extent that a part of the vibrator (to) is immersed, and then the valve a sieve is closed. Subsequently, the pressure reduction and pressurization section 00 is operated to return the inside of the processing tank a0 to atmospheric pressure. As a result, the space inside the processing tank H changes from a reduced pressure to a pressurized state, and the cleaning liquid (3) enters the trench (5).

At this time, the depressurization and pressurization parts Ωe are operated, and the processing tank (11
When the pressure inside the trench is reduced to 10 mHg - Woo BHg and returned to atmospheric pressure (760 wHg), the residual gas (6) will be removed from the trench (5) and if the planar dimensions of the opening are 1 μm x 1 μm and the depth is 5 μm, the residual gas (6) will be removed from the trench. Approximately 0 from the bottom of (5)
．． It occupies a volume up to a height of 0.06 to 0.6 μm.

In this state, the volume of the residual gas (6) is about +/8(') to ]/8 compared to the conventional example. (Figure 3(a)
).

Next, the vibrator 03 has a frequency of 75kHz2 and an output of n, 2
Operate w/d. As a result, cavitation 4 occurs within the cleaning liquid (3). The residual gas (6) in the trench (5) is sequentially split into the cleaning liquid (3) due to the shock wave generated when the cavitation a9 disappears, causing scattering and diffusion. (Figure 3(b)).

Approximately 2 to 3 minutes after the cavitation core occurs, the gas (6) in the trench (5) disappears. This ultrasonic treatment is continued for a predetermined period of time, for example, 10 minutes, so that foreign matter adhering to the side walls and bottom of the trench (5) is diffused out of the trench (5) and thoroughly cleaned.

(Figure 3 (C)).

After that, the drain pulp processor is opened, and the cleaning liquid (3) is drained from the drain pipe α. The wafer (4) is transferred to the outside of the cleaning tank uO through the loading/unloading door 02, and the wafer is removed by the drying device. (4) Dry.

If the wafer (4) is cleaned in this way, the wafer (4) can be cleaned.
4) Foreign matter adhering to the trench (5) formed above is effectively removed. By washing in this manner, it is possible to obtain products with improved quality.

In addition, in the above embodiment, the pressure inside the cleaning tank QO is reduced and the cleaning liquid (
After supplying the cleaning liquid (3), the pressure is returned to atmospheric pressure by 1, but the pressure in the cleaning tank aO is reduced, and even if the cleaning liquid (3) is not pressurized and remains in a depressurized state even after supplying the cleaning liquid (3), there will be residual pressure in the trench (5). The volume of gas (6) becomes sufficiently smaller than in the conventional method. In addition, if the pressure inside the cleaning tank qO is reduced and the pressure is increased to above atmospheric pressure after the cleaning liquid (3) is supplied, the residual gas (6) in the trench (5) will be returned to atmospheric pressure after the cleaning liquid (3) is supplied. It is possible to further reduce the volume compared to the case where the Any of these can produce the same effects as the above embodiment.

In addition, in the above embodiment, the recess has an opening size of 1 μm x 1 μm.
, a depth of 5 .mu.m and a depth of 8 degrees has been described, but it goes without saying that the same effect as described above can be obtained if the opening size is smaller and the depth is larger.

〔Effect of the invention〕

As described above, according to the present invention, the inside of the processing tank in which the substrate is accommodated is brought into a reduced pressure state, the cleaning liquid is supplied so that the substrate is immersed, and the ultrasonic vibration treatment is applied in this state. Since this cleaning method is used, the recesses formed on the substrate can be sufficiently cleaned, and a product with improved quality can be obtained.

Further, the cleaning liquid supply means for supplying the cleaning liquid to the processing tank in which the substrate is to be accommodated includes an ultrasonic generation means for applying ultrasonic vibration, and a depressurizer for adjusting the inside of the processing tank to a reduced pressure or pressurized state.
Since the cleaning device is equipped with a pressurizing means, it is possible to perform suitable cleaning and improve quality.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a cleaning apparatus according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a state in which a substrate is cleaned using the cleaning apparatus shown in FIG. 1, and FIG. a) ~ (c)
4 is a sectional view showing a process in which a trench portion, which is a main part of a substrate, is cleaned by the cleaning method of the present invention, FIG. 4 is a sectional view showing a state in which a substrate is cleaned using a conventional cleaning device, and FIG. This figure is a sectional view of a main part showing a state in which a trench portion of a substrate is cleaned by what is shown in FIG. 4. In the figure, (3) is cleaning solution, (4) is Uni-No,
(5) is a trench, (6) is residual gas, (1G is a cleaning tank, (c) is a vibrator, 04 is a cleaning liquid supply pipe, αG is a vacuum,
The pressurizing part, ng, is cavitation/. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (2)

[Claims] (1) The inside of the processing tank in which the semiconductor substrates are housed is reduced in pressure, and a cleaning liquid is supplied into the processing tank so that the substrates with the recesses formed therein are immersed in the cleaning liquid, and the substrates are subjected to ultrasonic vibration treatment. In addition, a method for cleaning a semiconductor substrate in which cleaning is performed by discharging gas remaining in the recesses. (2) a sealable processing tank in which a semiconductor substrate is to be housed; a cleaning liquid supply means for supplying a cleaning liquid into the processing tank;
A cleaning apparatus for semiconductor substrates, which is provided in the processing tank, and includes an ultrasonic generating means for applying ultrasonic vibration to the cleaning liquid, and a depressurizing means for adjusting the inside of the processing tank to a reduced pressure or pressurized state.