JPH05102118A - Method and apparatus for washing semiconductor wafer - Google Patents

Abstract

PURPOSE:To enhance a washing efficiency in an overflow type washing tank and to prevent recontamination of a semiconductor wafer at the time of finishing of washing. CONSTITUTION:An overflowing edge 13 is provided at an upper opening edge of a washing tank body 11, and a sub-pure water supply unit 17 is provided at a side opposed to the edge 13. Slits 14, 19 are respectively formed at the edge 13 and a pure water supply opening edge 18. Unidirectional surface water streams C, D, E are generated to become substantially laminar flows directed from the edge of the unit 17 toward the edge 13. Solution of impurities from the atmosphere can be suppressed by the surface water stream, and dusts floated on the water surface can be rapidly discharged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of rinsing a semiconductor wafer with an overflow type rinsing tank and a rinsing tank used for rinsing the semiconductor wafer.

[0002]

2. Description of the Related Art Conventionally, a semiconductor wafer is washed with water by immersing the semiconductor wafer in an overflow type washing tank. This will be described with reference to FIGS.

FIG. 5 is a sectional view showing a schematic structure of a conventional semiconductor wafer rinsing bath, and FIG. 6 is a plan view showing a state in which pure water is overflowing from the rinsing bath. In these figures, 1
Is a washing tank body, 2 is a pure water introducing pipe provided at the bottom of the washing tank body 1, 3 is a punching plate provided in the washing tank body 1, and is made of fluororesin, vinyl chloride resin, quartz glass or the like. Has been formed. 3a is a pure water introduction hole formed in the punching plate.

The washing bath main body 1 is formed in a box shape having a quadrangular shape in plan view, which opens upward, and its upper opening edge portion 1a.
Are formed at substantially the same height position on all four sides of the washing tank body 1. The reason why the washing bath main body 1 is formed in a quadrangular shape in plan view is to accommodate a large number of semiconductor wafers described later therein.

The pure water introducing pipe 2 is connected to a pure water supply device (not shown), and is constructed so that the pure water 4 is introduced from the pure water supply device into the washing tank body 1.

Reference numeral 5 is a semiconductor wafer.
A large number of wafer carriers 6 are loaded in the wafer carrier 6, and the wafer carriers 6 are immersed in the washing tank body 1.

In order to wash the semiconductor wafer 5 with the conventional washing bath having such a structure, the semiconductor wafer 5 is immersed together with the wafer carrier 6 in the washing bath main body 1 into which the pure water 4 is introduced in advance. .. During the washing with water, the pure water 4 is rectified by the punching plate 3 and rises, overflows from the upper opening edge 1a of the washing tank body 1 in all directions, and is discarded.

Then, simply, the pure water 4 is supplied and the washing is continued until the specific resistance value of the pure water 4 in the washing tank body 1 is restored to the level before the semiconductor wafer 5 is charged. As a special case, the washing time may be determined by the contact angle of water on the surface of the semiconductor wafer 5.

The washing time is set so as to wash away the treatment liquid such as hydrofluoric acid adhering to the semiconductor wafer 5, but if it is immersed for an unreasonably long time, a hydroxide film grows on the surface of the semiconductor wafer.
Since this is not preferable because it becomes a natural oxide film, the water repellency of the surface should be carefully determined while evaluating the contact angle as described above.

For example, when a gate oxide film is formed after washing with water or when epitaxial is performed, it is extremely important to control whether the semiconductor surface is hydrophilic or water repellent.

[0011]

Since the conventional washing tank is constructed as described above, overflow water when passing water (overflow water) is provided at the upper opening edge 1 of the washing tank body 1.
Although it is desirable that the pure water 4 overflows from a in all directions, the flow of the pure water 4 overflowing from the washing tank is as shown by the broken line arrow in FIG.

In FIG. 6, a broken line arrow A indicates a state of flowing so as to stay in the surface layer portion, and a broken line arrow B indicates a state of flowing so as to smoothly overflow.

When the pure water 4 satisfactorily overflows and is discharged, the waste water used to wash the semiconductor wafer 5 is quickly discharged,
It reduces pollution from the air on the surface of the water (often the decrease in resistivity due to the dissolution of carbon dioxide and impurities) and promotes the discharge of suspended dust.

However, in the stagnant state, conversely, waste water and floating dust are accumulated and the specific resistance value is lowered, and when the semiconductor wafer 5 is pulled out from the washing tank, contamination occurs again.
As a whole, there arises a problem that the washing effect is significantly impaired.

[0015]

A method of rinsing a semiconductor wafer according to the present invention comprises immersing a semiconductor wafer in a rinsing tank in which pure water supplied from a lower portion of a rinsing tank main body overflows from an upper opening edge, and rinsing with water. In this, a unidirectional water flow from one side of the washing tank to the other side is generated in the surface layer portion of pure water that fills the washing tank.

In the flush tank according to the present invention, one side of this upper opening edge is formed lower than the other side at the upper opening edge portion of the main body of the washing tank to provide an overflow edge portion, and the above-mentioned flush tank main body Pure water is supplied to the side opposite to the overflow edge portion separately from the semiconductor wafer accommodating portion, and a pure water supply opening having an opening width equal to the entire width of the overflow edge portion is provided at a position having substantially the same height as the overflow edge portion. An auxiliary pure water supply portion having an edge portion is provided, and at least one of the overflow edge portion and the pure water supply opening edge portion is provided with a number of upwardly opening slits.

Further, in the flush tank according to another invention, one side of the upper opening edge portion of the flush tank body is formed lower than the other side portion to provide an overflow edge portion at the upper opening edge portion of the flush tank body, and the flush tank is also provided. Pure water is pumped to a side portion of the main body facing the overflow edge portion through a route different from that of the semiconductor wafer accommodating portion, and a large number of pure water nozzles facing the overflow edge portion at a position having substantially the same height as the overflow edge portion. A sub-pure water supply unit provided with is provided.

[0018]

According to the present invention, during the washing with water, no accumulated portion is generated in the surface layer portion of the pure water filling the washing tank.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for washing a semiconductor wafer with water according to the present invention will be described in detail below with reference to FIGS.

FIG. 1 is a sectional view showing a schematic structure of a washing tank according to the present invention, and FIG. 2 is a perspective view showing a state where a semiconductor wafer is being washed with the washing tank according to the present invention. In these figures, the same or equivalent members as those described in FIGS. 5 and 6 are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG. 1 and FIG. 2, 11 is a washing tank according to the present invention, and the washing tank main body 12 of the washing tank 11 is formed in a box shape of a quadrangular shape in plan view that opens upward.

At the upper opening edge of the flush tank body 12,
The overflow edge portion 13 is provided by forming one side of the upper opening edge portion lower than the other side portion. On the overflow edge portion 13, a large number of slits 14 opening upward are arranged in parallel at equal intervals.

Further, in the main body 12 of the washing tank, a semiconductor wafer accommodating portion 15 for accommodating the semiconductor wafer 5 together with the wafer carrier 6, and the semiconductor wafer accommodating portion 15 are separated from each other by the partition plate 1.
And a sub-pure water supply unit 17 defined by the reference numeral 6.

The sub-pure water supply part 17 is one side of the washing tank body 12 formed in a quadrangular shape in plan view, and is the overflow edge part 13.
It is arranged on the side portion facing to, and the opening portion on the upper side is opened with a size equal to the opening width of the overflow edge portion 13 (opening width of the washing tank main body 12).

The partition plate 16 is formed so that the upper edge thereof has substantially the same height as the overflow edge portion 13, and the pure water supply opening edge portion 18 is provided on the upper edge of the partition plate 16. ing. A large number of slits 19 are also arranged in parallel in the pure water supply opening edge portion 18 similarly to the overflow edge portion 13.

The semiconductor wafer accommodating portion 15 and the sub-pure water supplying portion 17 are communicated with each other under the punching plate 3, and the pure water 4 supplied from the pure water introducing pipe 2 is supplied to the semiconductor wafer accommodating portion 15 and the sub-pure water. It is configured to be distributed to the supply unit 17.

Note that, in FIG. 2, broken lines C, D and E indicate the water flow in the surface layer portion of the pure water 4 which fills the washing tank body 12 (hereinafter, this water flow is simply referred to as surface water flow).

Next, a method of rinsing a semiconductor wafer using the rinsing tank 11 thus constructed will be described.

First, pure water 4 is supplied into the main body 12 of the washing tank to fill the semiconductor wafer accommodating portion 15 and the sub pure water supplying portion 17 with the pure water 4. Then, the semiconductor wafer 5 together with the wafer carrier 6 is immersed in the semiconductor wafer accommodating portion 15 while continuously supplying the pure water 4.

In this way, the semiconductor wafer 5 is cleaned by the water flow rising through the punching plate 3. On the other hand, in the upper part of the washing tank body 12, the pure water 4 overflows from the deionized water supply opening edge portion 18 of the auxiliary deionized water supply portion 17 and overflows from the overflow edge portion 13 to the outside of the washing tank body 12. Then, a unidirectional surface water flow is generated from the pure water supply opening edge portion 18 toward the overflow edge portion 13 side.

The surface water flow is rectified by the slit 19 when the pure water 4 overflows from the pure water supply opening edge portion 18. The rectified surface water streams C, D, E flow slightly swell on the water surface, and are rectified again by the slit 14 of the overflow edge portion 13 located on the downstream side to reach drainage.

As described above, when washing is performed in the state where the surface water streams C, D, E are generated, the dust floating on the water surface does not stay and is discharged along the surface water streams C, D, E. In addition, the waste water used to wash the semiconductor wafer 5 also overflows by the surface water streams C, D and E without staying on the water surface.
3 and is discharged to the outside of the washing tank body 12.

That is, since the flow directions of the surface water streams C, D, and E are constant, the flow velocity becomes faster, and as a result, the exchange rate of pure water on the water surface increases.

Further, when the surface water flows C, D, E are fast, it is possible to minimize the influence of contacting with the atmosphere and reducing the specific resistance value of pure water. Further, when the surface water streams C, D, and E are rectified by the slits 14 and 19 to be in a laminar flow state, the effect of suppressing rising of fine particles existing in the atmosphere and the washing tank and entrainment is high, and the semiconductor after the washing is finished. The fine particles remaining on the wafer 5 are extremely small.

The number of fine particles remaining on the semiconductor wafer 5 after washing with water is shown in Table 1 below.

[0035]

[Table 1]

Table 1 compares the number of fine particles remaining in the semiconductor wafer washed in the conventional washing tank with the semiconductor wafer washed in the washing tank 11 described in this embodiment. According to Table 1, it can be seen that the semiconductor wafer washed in the water washing tank 11 described in this example has a small amount of adhering particles and a large rectifying effect.

In this embodiment, the slits 14 and 18 are provided on the upstream side and the downstream side of the surface water flow, respectively. However, in the case where the washing tank is relatively small, either the upstream side or the downstream side is provided. Even if only one of the slits is provided, the surface water flow is rectified, and a laminar flow effect can be expected. When the washing tank is large, it is possible to prevent the surface water flow from becoming turbulent by providing slits on both the upstream side and the downstream side.

Next, a water washing tank according to another invention will be described with reference to FIGS. 3 and 4. FIG. 3 is a cross-sectional view showing a schematic configuration of a water washing tank according to another invention, and FIG. 4 is a graph showing the relationship between the water washing time and the specific resistance value of pure water. In these figures, the same or equivalent members as those described in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 3, reference numeral 21 denotes a water washing tank, and the water washing tank main body 22 of the water washing tank 21 is provided with a sub pure water supply unit 24 having a pure water nozzle 23 on the side facing the overflow edge 13. There is.

The sub-pure water supply section 24 is separated from the semiconductor wafer accommodating section 15 by a partition plate 25, and a sub-chamber 26 that communicates with the sub-chamber 26 and is separate from the pure water introducing pipe 2. A pure water introduction pipe 27 is provided. Pure water introduction pipe 27
Is connected to a pressure device (not shown), and is configured so that the pure water 4 is pumped at a pressure higher than the pure water pressure in the pure water introducing pipe 2.

Further, the pure water nozzle 23 has the overflow edge portion 1
A plurality of deionized water outlets are provided in parallel at positions having substantially the same height as 3, and the deionized water outlet is directed toward the overflow edge portion 13. The pure water 4 pressure-fed to the sub chamber 26 is ejected toward the overflow edge portion 13.

In the water washing tank 21 thus constructed, the pure water 4 is pressure-fed to the pure water introducing pipe 27 during the water washing and jetted from the pure water nozzle 23. The pure water 4 ejected from the pure water nozzle 23 causes a surface water flow F in one direction toward the overflow edge 13 on the surface layer of the water surface.

Therefore, when the surface water flow F is generated by the water jetted from the pure water nozzle 23 as described above, the speed and pressure of the surface water flow F increase, so that the inside of the water washing tank 21 is contaminated. The recovery time can be shortened.

In particular, the amount of pure water 4 ejected from the pure water nozzle 23 and the pure water 4 supplied through the punching plate 3
Since it is possible to control the amount of water separately, when the installation environment of this washing tank 21 is not preferable, for example, when there is a relatively large amount of dust in the atmosphere, or when comparing mist / fume with water-soluble harmful substances such as acids and alkalis. When the amount is extremely large, the amount of pure water from the pure water nozzle 23 can be increased to minimize the pollution from the atmosphere.

The time required for the specific resistance on the water surface of the washing tank to recover is compared between the washing tank 21 described in this embodiment and the conventional washing tank, as shown in FIG. The solid line in FIG. 4 indicates the washing tank 21 described in this embodiment.
When using, the broken line shows the case where a conventional washing tank is used.

According to FIG. 4, in the conventional washing tank, the amount of impurities dissolved in the atmosphere affects the recovery of the specific resistance value very slowly, and in the washing tank 21 of this embodiment, the influence of the atmosphere is reduced. I know that there is.

[0047]

As described above, in the method of rinsing a semiconductor wafer according to the present invention, the semiconductor wafer is immersed in a rinsing tank in which pure water supplied from the lower part of the rinsing tank body overflows from the upper opening edge, During rinsing, a unidirectional water flow from one side of the rinsing tank to the other side is generated in the surface layer portion of the pure water filling the rinsing tank, and the rinsing tank according to the present invention is the upper side of the rinsing tank body. At the opening edge portion, one side of the upper opening edge portion is formed lower than the other side portion to provide an overflow edge portion, and at the side portion of the washing tank body facing the overflow edge portion, the semiconductor wafer accommodating portion is Separately, a sub-pure water supply unit is provided in which pure water is supplied and a pure water supply opening edge portion having an opening width equal to the entire width of the overflow edge portion is formed at a position substantially the same height as the overflow edge portion, At least one of the overflow edge and the pure water supply opening edge has a top In the washing tank according to another invention, one side of the upper opening edge portion is formed lower than the other side portion in the upper opening edge portion of the washing tank body. In addition to providing an overflow edge, pure water is pressure-fed to a side portion of the flush tank body facing the overflow edge through a route different from that of the semiconductor wafer accommodating portion, and overflows to a position having substantially the same height as the overflow edge. Since the auxiliary deionized water supply unit provided with a large number of deionized water nozzles facing the edge is provided, no stagnation occurs in the surface layer portion of the deionized water that fills the washing tank during washing.

Therefore, deterioration of water quality on the water surface can be suppressed, and floating dust can be promptly discharged, so that the effect of washing the semiconductor wafer with water can be enhanced.

If a large number of slits are provided on at least one of the upstream side and the downstream side of the surface water flow, the adhesion and retention of fine particles on the semiconductor wafer will be reduced.

Further, the surface water flow can be sped up by ejecting pure water from the pure water nozzle to generate the surface water flow. Can be installed.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a washing tank according to the present invention.

FIG. 2 is a perspective view showing a state in which a semiconductor wafer is washed with water in a water washing tank according to the present invention.

FIG. 3 is a cross-sectional view showing a schematic configuration of a washing tank according to another invention.

FIG. 4 is a graph showing the relationship between the washing time and the specific resistance value of pure water.

FIG. 5 is a sectional view showing a schematic configuration of a conventional water washing tank for semiconductor wafers.

FIG. 6 is a plan view showing a state in which pure water is overflowing from a conventional washing tank.

[Explanation of symbols]

 4 Pure Water 5 Semiconductor Wafer 11 Rinsing Bath 12 Rinsing Bath Main Body 13 Overflow Edge 14 Slit 15 Semiconductor Wafer Housing 17 Sub Deionized Water Supply Section 18 Pure Water Supply Opening Edge 19 Slit 21 Rinsing Tank 22 Rinsing Tank Main Body 23 Pure Water Nozzle 24 Sub pure water supply unit

Claims (3)

[Claims] 1. A semiconductor wafer is immersed in a washing tank in which pure water supplied from the lower portion of the washing tank body overflows from the upper opening edge, and during washing, the surface of pure water that fills the washing tank is washed with a washing tank. A method for rinsing a semiconductor wafer with water, which comprises causing a water flow in one direction from one side to the other side. 2. A rinsing tank in which pure water is supplied to a lower portion of a rinsing tank main body for accommodating semiconductor wafers, and pure water overflows from an upper opening rim of the rinsing tank main body. In addition, one side of the upper opening edge portion is formed lower than the other side portion to provide an overflow edge portion, and the side portion of the washing tank body facing the overflow edge portion is provided with pure water separately from the semiconductor wafer accommodating portion. Is provided and a sub-deionized water supply portion is provided in which a pure water supply opening edge portion having an opening width equal to the entire width of the overflow edge portion is formed at a position that is substantially the same height as the overflow edge portion. A washing tank characterized in that a large number of slits that open upward are provided on at least one of the above-mentioned portion and the opening edge portion for supplying pure water. 3. A rinsing tank in which pure water is supplied to a lower portion of a rinsing tank main body containing a semiconductor wafer and pure water overflows from an upper opening rim of the rinsing tank main body. In addition, one side of the upper opening edge portion is formed lower than the other side portion to provide an overflow edge portion, and a side different from the semiconductor wafer accommodating portion is provided on a side portion of the washing tank body facing the overflow edge portion. A washing tank characterized in that an auxiliary deionized water supply unit is provided, which is provided with a large number of deionized water nozzles that face the overflow edge at a position where pure water is pumped and has a height substantially the same as the overflow edge.