JPH11260779A - Equipment and method for spin cleaning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always wet the whole region of a substrate at the time of scanning with a nozzle, and make a new cleaning liquid supply system and a complex moving system unnecessary, by arranging a bar stretched from a rotating shaft and a plurality of nozzles on a line making the bar a normal or on a circular arc. SOLUTION: This spin cleaning equipment is provided with a means holding rotatably a substrate 1 to be cleaned in a cleaning tank, and nozzles 4 supplying cleaning liquid which have vibrators 3 applying vibration of ultrasonic wave or the like to the cleaning liquid. A bar stretched from a rotating shaft 2 and a plurality of the nozzles 4 are arranged on a line making the bar 3 a normal. In another case, a rectilinear bracket 8 is fixed to the bar 3, and a plurality of nozzles are installed on the fixed bracket 8. The bar 3 holding the nozzles 4 via the bracket 8 scans, and the whole region of the substrate 1 is directly irradiated with the cleaning liquid. While vibration is applied to the cleaning liquid with an ultrasonic vibration element 9 in each of the nozzles 4, the cleaning liquid is supplied to the substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin cleaning apparatus and a spin cleaning method, and more particularly, to cleaning a substrate (silicon wafer or glass) for producing a device in a process of producing a semiconductor device or a liquid crystal display device. Cleaning apparatus and a spin cleaning method for the same.

[0002]

BACKGROUND OF THE INVENTION Semiconductor devices formed on semiconductor substrates are becoming denser and smaller to submicron levels. In order to achieve high densification, the surface of the substrate must be kept ultra-clean. That is, organic substances, metals, various particles, and oxides (oxide films) must be removed from the entire substrate. Therefore, substrate cleaning is performed.

[0003] With the increase in the diameter of the substrate, a batch type cleaning apparatus in which a plurality of substrates, which has been the mainstream in the past, is immersed in a cleaning tank storing a cleaning liquid to perform cleaning, is moved from a batch type cleaning apparatus to a rotatable holder. The conversion to a single-wafer spin cleaning apparatus in which a substrate is rotated by mounting and a cleaning liquid is dropped from above is attempted.

[0004] The former occupies a large area for processing a plurality of sheets, and the apparatus is further increased in size as the diameter of the substrate increases. A large amount of pure water is used for rinsing. The latter has a small device area and can greatly reduce the amount of pure water used. The latter is desirable in view of the layout of the clean room and the burden on utilities.

[0005] In the case of a spin cleaning device, 800 k
It is common to use a nozzle-type ultrasonic generator that supplies a substrate with vibration at a frequency of Hz to 2 MHz. In order to remove the fine particles in the cleaning of the substrate, it is indispensable to irradiate the ultrasonic waves and separate the fine particles from the substrate by the vibration. In the nozzle type ultrasonic generator, the area of the liquid ejection port is small.

[0006] In order to remove fine particles, it is essential to apply a vibration-applied cleaning liquid to the substrate. The ability of the vibrated cleaning liquid to remove fine particles has a spread of several centimeters around the drop point. If a plurality of nozzles are arranged on the substrate and spin cleaning is performed, fine particles can be removed without scanning the nozzles.

However, uniform processing cannot be performed. Also, vibrations from adjacent nozzles may cancel each other, and fine particles may remain in stripes. In order to perform a uniform treatment on the entire surface of the substrate, it is important to directly irradiate the entire surface of the substrate with a cleaning liquid subjected to vibration. For that purpose, the nozzle must be scanned.

With the single nozzle shown in FIG. 6, it takes a long time to scan the entire substrate. This becomes more remarkable as the diameter of the substrate increases.

Even if a plurality of nozzles are arranged in parallel with the bar holding the nozzles (FIG. 7), there is no noticeable reduction in time. A common problem is that when the nozzle is scanned, the center of the substrate dries. Drying of the entire area of the cleaning substrate during the wet process must be avoided due to adhesion of fine particles and excessive reaction between the cleaning liquid and the substrate.

In order to prevent this, it is necessary to always provide a nozzle for supplying the liquid to the center (FIG. 8). However, a new mechanism, specifically, a cleaning liquid supply system and a system for holding the same are required. In addition, they both cross because they want to supply the cleaning liquid to the center. Further, it is not preferable that there are many objects, especially movable parts, in the cleaning apparatus, especially on the upper surface of the substrate.

If the nozzle is scanned in parallel with the bar extended from the rotation axis, the entire substrate is not dried, but a complicated movable system capable of rotating and scanning in parallel is required (FIG. 9). In this case, a space is required when the bar is pulled, which increases the area of the apparatus, which is not preferable. SUMMARY OF THE INVENTION It is an object of the present invention to provide a spin cleaning method and a spin cleaning apparatus for directly irradiating a cleaning liquid having a vibration applied to the entire substrate.

[0012]

SUMMARY OF THE INVENTION The present invention provides a spin cleaning apparatus which does not require a new cleaning liquid supply system and does not require a complicated movable system because the entire area of the substrate is always wet when scanning the nozzle. And a spin cleaning method.

[0013]

A spin cleaning apparatus according to the present invention comprises means for rotatably holding a substrate to be cleaned in a cleaning tank, and a nozzle for supplying a cleaning liquid. In a spin cleaning apparatus having a nozzle provided with a vibrator for providing a vibration, a bar extended from a rotation axis and a plurality of nozzles are arranged on a straight line or an arc having the bar as a normal line. Features.

A spin cleaning method according to the present invention includes a vibrator having means for rotatably holding a substrate to be cleaned in a cleaning tank and a nozzle for supplying a cleaning liquid, and applying vibration such as ultrasonic waves to the cleaning liquid. In a spin cleaning apparatus having a nozzle provided with a plurality of nozzles arranged in a straight line or a circle having a bar extending from a rotation axis and a bar extending from the rotation axis, a nozzle between the plurality of nozzles is provided. It is characterized in that the entire area of the substrate is directly irradiated with the vibrated cleaning liquid by scanning the nozzles by the pitch width.

[0015]

(Embodiment 1) FIGS. 1, 2 and 3
1 shows an embodiment of the present invention.

In this embodiment, means (not shown) for rotatably holding a substrate 1 to be cleaned in a cleaning tank (not shown);
In a spin cleaning apparatus having a nozzle 4 having a nozzle 4 for supplying a cleaning liquid and a vibrator 3 for applying vibration such as ultrasonic waves to the cleaning liquid, a bar 3 extended from a rotating shaft 2, A plurality of nozzles 4 are arranged in a straight line with 3 as a normal line. In the example shown in FIGS. 1 and 2, a linear bracket 8 is fixed to the bar 3, and a plurality of nozzles are attached to the bracket 8.

This will be described in more detail below. First, a square glass substrate, a quartz substrate, a circular silicon wafer, or the like is fixed on a substrate holder in a cleaning tank.

If necessary, the pressure in the cleaning tank is reduced, and high-purity nitrogen is supplied to purge the tank. The substrate 1 is rotated, and the cleaning liquid is ejected from the nozzle 4. The rotation speed at this time is preferably 500 to 1500 rpm.

The cleaning liquid is supplied to the substrate 4 while applying a vibration of a frequency of 800 kHz to 2 MHz to the cleaning liquid by the ultrasonic vibration element 9 provided in each nozzle 4. The bar 3 holding the nozzle 4 is scanned through the bracket 8 to directly irradiate the entire surface of the substrate 1 with the cleaning liquid. At this time, the scanning amount (that is, the moving amount of the bar 3) may be adjusted by the pitch width 1 between the nozzles 4. The supply amount of the cleaning liquid is 600 to 1500
It is preferably set to cc / min.

The washing liquid used in the present invention is selected from pure water, ultrapure water, ozone-added ultrapure water, hydrofluoric acid, aqueous hydrogen peroxide, ammonium hydroxide, sulfuric acid, hydrochloric acid, isopropyl alcohol and the like. At least one or at least two mixed liquids selected from these are exemplified.

Further, the washing steps with some washing liquids may be performed in a time series. If necessary, dry nitrogen is sprayed onto the washed substrate to dry the substrate.

The cleaning liquid used in the present invention includes pure water to which ozone has been added, and a mixed liquid of hydrofluoric acid, hydrogen peroxide and pure water.

More preferably, ozone-added pure water, hydrofluoric acid, hydrogen peroxide solution, a surfactant, and pure water are prepared, and a washing step with ozone-added pure water is performed. It is preferable that a washing step with pure water containing an agent, a washing step with ozone-added pure water, a washing step with diluted hydrofluoric acid, and a washing step with pure water can be sequentially performed. This cleaning method is effective even at room temperature, and does not need to be heated to about 100 ° C. unlike the conventional RCA cleaning.

(Embodiment 2) FIG. 4 shows another embodiment.
The bracket 8 shown in FIG. 1 is a straight bracket, but in this example, a bracket on an arc is used. Here, the arc includes a circle, an ellipse, a hyperbola, and a parabola. Other points are form example 1.
Is the same as

(Embodiment 3) FIG. 5 shows another embodiment. In the example shown in FIG. 4, the bracket 8 has an arc shape having its center on the rotation shaft 2 side, but in this example, the bracket 8 has an arc shape having its center on the opposite side to the rotation shaft 2. Other points are form example 1.
Is the same as

[0026]

EXAMPLE In this example, an 8-inch silicon wafer was cleaned using the spin cleaning apparatus shown in FIG.

Washing was performed by a spin washing method. The entire substrate was contaminated with alumina particles.

The silicon substrate is subjected to a vibration of a frequency of 1.5 MHz while applying 0.5% HF and 0.5% H ₂ O _2.
Washing with ultrapure water containing and 50 ppm of a surfactant was performed for 8 seconds, 16 seconds, 24 seconds, and 32 seconds. At that time, the nozzle was scanned and the entire area of the substrate was directly irradiated with the vibrated cleaning liquid. Thereafter, rinsing with ultrapure water was performed for 16 seconds.

As a conventional example 1, scanning was performed with the nozzle of the form shown in FIG. 1, and as an example, the scanning was performed with the nozzle of the form shown in FIG.

The rotation speed at this time was 1000 rpm. The number of fine particles on the substrate after cleaning was measured by a surface foreign matter inspection device, and the result of calculating the fine particle removal rate is shown in Table 1. The evaluation fine particle diameter is 0.20 μm or more.

[0031]

[Table 1] In the conventional example, a long time as long as 32 seconds is required for sufficient removal. In the example, the removal was sufficient by 16 seconds.

[0032]

The effects of the present invention are as follows. Cleaning time is faster than scanning a single nozzle compared to equivalent cleaning performance using other nozzles. Unlike the case where a single nozzle and a plurality of nozzles are provided in parallel with the bar and scanning is performed, the center of the substrate does not dry.

There is no need to newly provide a cleaning liquid supply system for keeping the center of the substrate from drying out and a system for holding the same. Since the center of the substrate does not dry, there is no need to provide a complicated movable system.

[Brief description of the drawings]

FIG. 1 is a plan view showing a state in which a plurality of nozzles arranged on a straight line perpendicular to a bar extended from a rotation axis are rotated and scanned according to Embodiment 1 of the present invention.

FIG. 2 is a perspective view showing a state in which a cleaning liquid is jetted from a plurality of ultrasonic jet nozzles.

FIG. 3 is a perspective view of an ultrasonic jet nozzle.

FIG. 4 is a plan view showing a state in which a plurality of nozzles arranged in an arc having a center on the rotation axis side are rotationally scanned according to the second embodiment of the present invention.

FIG. 5 is a plan view showing a state in which a plurality of nozzles arranged on an arc whose center is on the opposite side to the rotation axis are rotationally scanned according to the third embodiment of the present invention.

FIG. 6 is a plan view showing a state in which a single nozzle is rotationally scanned according to a conventional example.

FIG. 7 is a plan view showing a state in which a plurality of nozzles provided in parallel with a bar extending from a rotation axis are rotationally scanned according to a conventional example.

FIG. 8 is a plan view showing a state in which a mechanism for constantly supplying a cleaning liquid to the center of a substrate is provided according to a conventional example.

FIG. 9 is a plan view showing a state in which a plurality of nozzles provided in parallel with a bar extending from a rotation axis are scanned in parallel according to a conventional example.

[Explanation of symbols]

 Reference Signs List 1 substrate to be cleaned, 2 rotating shaft for scanning, 3 bar for holding nozzle, 4 nozzle, 5 pipe for always dropping cleaning liquid at the center of substrate, 6 bar for holding pipe, 7 table for holding bar, 8 Bracket for mounting nozzle, 9 Ultrasonic vibration element.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuhisa Nitta 4-1-1 Hongo, Bunkyo-ku, Tokyo Ultra Clean Technology Development Laboratory Co., Ltd. (72) Inventor Mitsunori Nakamori Aramaki Aoba-ku, Aoba-ku, Sendai, Miyagi Prefecture Aoba (unnumbered) Tohoku University

Claims (2)

[Claims] 1. A nozzle having means for rotatably holding a substrate to be cleaned in a cleaning tank and a vibrator having a nozzle for supplying a cleaning liquid and applying vibration such as ultrasonic waves to the cleaning liquid. A spin cleaning device comprising: a bar extended from a rotation axis; and a plurality of nozzles arranged on a straight line or an arc having the bar as a normal line. 2. A spin cleaning apparatus according to claim 1, wherein the entire area of the substrate is directly irradiated with a cleaning liquid having a vibration by scanning the nozzles by a nozzle pitch width between a plurality of nozzles. Cleaning method.