JP2000183005A - Wafer cleaning method and cleaning apparatus - Google Patents

Abstract

(57) [Problem] To provide a wafer cleaning method for improving in-plane uniformity of a chemical treatment effect. According to the method, a wafer is subjected to a chemical treatment using a single-tank type cleaning apparatus having a single cleaning tank having a cleaning tank supplied with a chemical solution and pure water from the bottom and overflowing from the top. This is a method of cleaning a wafer by rinsing cleaning. The method includes the steps of: supplying pure water to a cleaning tank via a pure water supply pipe 52 to make the cleaning tank full; immersing the wafer W in pure water in the cleaning tank; And replacing the pure water in the cleaning tank with a chemical solution while overflowing the pure water, and stopping the supply of the chemical solution when the pure water is replaced with the chemical solution, and performing the chemical solution treatment for a predetermined time. And supplying pure water to replace the chemical in the cleaning tank with pure water while causing the chemical to overflow.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for cleaning a wafer, and more particularly, to a method and an apparatus for cleaning a wafer in which the in-plane uniformity of a chemical treatment effect of the wafer is improved. is there.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor device, a wafer cleaning apparatus is used to clean a wafer before and after most of the process steps to remove chemicals, particles, or contaminants attached to the wafer. Wafer cleaning apparatuses are roughly classified into single-tank type cleaning apparatuses and double-tank type cleaning apparatuses according to the number of cleaning tanks. The single-tank type cleaning apparatus is a cleaning apparatus that performs chemical treatment of a wafer and rinses the wafer with pure water following the chemical processing using one and the same cleaning tank. A cleaning apparatus including a chemical treatment tank for processing and a rinse cleaning tank for rinsing with pure water, wherein the chemical treatment of the wafer is performed in the chemical treatment tank, and the rinsing of the wafer with pure water is performed in the rinse cleaning tank. It is.

Here, the configuration of a conventional single-tank-type wafer cleaning apparatus will be described with reference to FIG. FIG. 7 is a schematic sectional view showing the configuration of a conventional single-tank type wafer cleaning apparatus.
As shown in FIG. 7, a conventional single-tank type wafer cleaning apparatus 10 (hereinafter, simply referred to as a cleaning apparatus 10) includes one processing tank 12 having an open-top cylindrical shape and an inverted pyramid-shaped bottom, and An outer tank 18 is provided so as to surround the periphery of the upper part of the tank 12 and has an outer wall 16 higher than the upper edge of the side wall 14 of the processing tank 12. A pure water supply pipe 22 having an on-off valve 20 is connected to the bottom of the processing tank 12 to supply pure water to the processing tank 12, and a chemical solution supply pipe 26 having an on-off valve 24 is connected to the on-off valve 20. Pure water supply pipe 2 between tank 12
2 and supplies a chemical solution to the treatment tank 12 via the pure water supply pipe 22. A drain pipe 28 is connected to the bottom of the outer tank 18.

[0006] At the bottom of the processing tank 12, a straightening plate 30 having a large number of through-holes with a uniform distribution or a non-uniform distribution is provided.
Is provided, and the pure water or the chemical supplied to the bottom of the processing tank 12 via the pure water supply pipe 22 and the chemical liquid supply pipe 26 is dispersed in the processing tank 12 with a uniform and undisturbed flow. In addition, stirring nozzles 32A and 32B for jetting pure water to stir the inside of the processing tank 12 are provided above the flow rectifying plate 30 respectively.
It is provided along two opposing side walls.

Next, referring to FIG. 8, a conventional cleaning apparatus 1 will be described.
A method of cleaning a wafer using 0 will be described. FIG.
(A), (b) and (c) are each a schematic cross-sectional view of the apparatus showing the state of the cleaning apparatus 10 in each step for explaining a conventional wafer cleaning method. The conventional cleaning method includes a chemical liquid supply step, a chemical liquid treatment step, a chemical liquid replacement step, and a pure water rinse cleaning step. First, in the chemical solution supply step, as shown in FIG. 8A, the release valve 22 is closed, while the release valve 24 is opened, and the chemical solution supply pipe 26 is opened.
The chemical is supplied to the processing tank 12 through the, and the processing tank 12 is filled with the chemical.

After filling the processing tank 12 with a chemical, the process proceeds to a chemical processing step, the opening valve 24 is closed, and the wafer W is immersed in the chemical in the processing tank 12 as shown in FIG. hand,
The wafer W is cleaned with a chemical. Next, in the chemical solution replacement step, as shown in FIG. 8C, the opening valve 20 is opened, pure water is supplied to the cleaning tank 12 through the pure water supply pipe 22, and the chemical solution in the processing tank 12 is removed. Purging with pure water, discharging the chemical solution to the outside via the outer tank 18 and the drain pipe 28,
2 is cleaned with pure water. In the pure water rinsing cleaning step, the wafer W in the processing tank 12 is further rinsed with pure water while supplying pure water following the chemical liquid replacement step.

As described above, the pure water rinsing is performed after the wafer is subjected to the chemical treatment in the chemical treatment step, and then the pure water is supplied in the chemical substitution step and the pure water rinse step in the same cleaning tank 12.

[0008]

However, in the conventional cleaning apparatus and cleaning method, in the chemical processing of the wafer, not only in the chemical processing step but also in the chemical replacement step, the chemical in the cleaning tank 12 is completely purified by pure water. Since the process is substantially continued until the replacement is performed, there is a problem that the following non-uniformity or in-plane variation of the wafer surface of the chemical solution processing effect occurs.
That is, during the immersion of the wafer in the chemical solution in the chemical solution processing step, the chemical solution is almost stationary, so the effect of the chemical solution treatment on the wafer is almost uniform within the wafer surface, and the in-plane variation of the cleaning effect hardly occurs. . However, in the chemical solution replacement step, the replacement of the chemical solution with the pure water proceeds promptly in a region where the pure water flows at a high flow rate, and as a result, the effect of the chemical solution treatment on the wafer in that region is reduced. Conversely, in a region where the flow rate of the pure water is low, the progress of the substitution from the chemical solution to the pure water is slow, and as a result, the effect of the chemical treatment of the wafer in that region is increased. In other words, the slowness of the flow rate of the pure water causes a variation in the treatment effect of the chemical solution.
If the cleaning effect of the wafer varies as described above, trouble occurs in a subsequent process step, and the product yield of the semiconductor device decreases.

Therefore, in the conventional cleaning apparatus and the conventional cleaning method, the shape of the current plate is devised to make the flow of pure water uniform, in order to make the chemical treatment effect and the rinsing effect on the wafer uniform and uniform. Pure water is supplied from a stirring nozzle to create a jet of pure water, so that the pure water is uniformly dispersed and collided with the wafer. As described above, in the conventional cleaning apparatus and the conventional cleaning method, although an attempt is made to level the flow of pure water flowing into the treatment tank 12 so as to be uniform by devising the shape of the current plate. In any case, the flow of pure water in the region near the pure water supply port at the bottom of the treatment tank 12 is
It is faster than the peripheral area of the processing tank 12, and it is difficult to eliminate the in-plane non-uniformity of the chemical solution processing effect. In addition, even if the pure water is jetted from the stirring nozzle to stir the chemical solution and the pure water in the treatment tank 12, basically, only the inside of the washing tank is stirred, and the flow of the pure water is controlled as desired. It was difficult to make the flow uniform.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for cleaning a wafer, which improve the in-plane uniformity of a chemical solution treatment effect.

[0011]

The inventor of the present invention has determined that the in-plane non-uniformity of the chemical treatment effect is caused by the replacement of the chemical solution with pure water. In order to improve the problem, the problem of the conventional wafer cleaning method using the single-tank type cleaning apparatus is provided by providing a step having an effect opposite to the replacement of the chemical solution with pure water, that is, a step of replacing the pure water with the chemical solution. We thought that it could be solved and repeated experiments to complete the present invention. Furthermore, the present invention is intended to eliminate the non-uniformity during the rinsing with pure water and to cancel the non-uniformity in the pre-treatment by pretreatment, that is, pure water by a chemical solution. By supplying the chemical solution to the cleaning tank through the replacement of the wafer, the wafer is given an in-plane non-uniformity of the chemical solution processing effect opposite to that of the pure water rinse in which the chemical solution is replaced with pure water, and as a result, a uniform chemical solution treatment is obtained. Have to be able to.

In order to achieve the above object, based on the above findings, a method for cleaning a wafer according to the present invention comprises a cleaning tank which supplies a chemical solution and pure water from the bottom and overflows from the top. A wafer cleaning method using a single-tank type cleaning apparatus having the same, followed by rinsing with pure water, a step of supplying pure water to the cleaning tank to make it full, and a step of pure water in the cleaning tank. Immersing the wafer in the inside, supplying the chemical solution, replacing the pure water in the cleaning tank with the chemical solution while overflowing the pure water, and stopping the supply of the chemical solution when the pure water is replaced with the chemical solution The method is characterized by including a step of performing a chemical solution treatment for a predetermined time and a step of supplying pure water and replacing the chemical solution in the cleaning tank with pure water while overflowing the chemical solution.

The chemical treatment performed in the present invention is the same as a conventional chemical treatment, for example, a treatment simply by immersion of a wafer or a treatment by circulation of a chemical. Although it depends on the method,
This is the same as the time required for conventional chemical treatment. Further, the method of the present invention can be applied to wafer cleaning regardless of the type of chemical solution as long as a single-tank type cleaning apparatus is used. Preferably, after the chemical solution in the cleaning tank is replaced with pure water, a step of supplying pure water to the cleaning tank for a predetermined time and rinsing the wafer with the pure water is provided. In the step of performing the chemical solution treatment for a predetermined time, the chemical solution may be circulated as described above.

In order to carry out the method of the present invention, the single-wafer cleaning apparatus for a wafer according to the present invention has one cleaning tank for supplying a chemical solution and pure water from the bottom and overflowing from the top. A single-tank type cleaning apparatus for cleaning wafers in a cleaning tank, comprising a flow rate adjusting mechanism for adjusting a flow rate of pure water, pure water supply means for supplying pure water to the cleaning tank,
It is characterized by comprising a flow rate adjusting mechanism for adjusting the flow rate of the chemical solution, and a chemical solution means for supplying the chemical solution to the cleaning tank.

In the present invention, a plurality of chemical liquid supply means may be provided, each supplying a different kind of chemical liquid. In the present invention, the pure water supply means and the chemical liquid supply means each have a flow rate adjusting mechanism for adjusting the flow rates of the pure water and the chemical liquid, so that the supply flow rate of the chemical liquid in the step of replacing the pure water with the chemical liquid, and ,
The time required for replacement in the cleaning tank can be adjusted by adjusting the supply flow rate of pure water in the step of replacing the chemical solution with pure water, so that the in-plane uniformity of the chemical solution treatment effect can be further improved. it can. Further, in the present invention, the chemical solution means a chemical solution diluted with pure water. By supplying the chemical solution and pure water to the cleaning tank while controlling the flow rates at the same time, a high-concentration pure solution not diluted with pure water as a chemical solution. Chemicals can also be used.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the accompanying drawings based on embodiments. Embodiment 1 of Cleaning Apparatus This embodiment is an example of an embodiment of a single-wafer cleaning apparatus for a wafer according to the present invention, and FIG. 1 is a configuration of a single-tank cleaning apparatus for a wafer according to the present embodiment. FIG. As shown in FIG. 1, a single-tank-type cleaning apparatus 40 (hereinafter simply referred to as a cleaning apparatus 40) for a wafer according to the present embodiment includes a processing tank 42.
And an outer wall 46 that is provided so as to surround the periphery of the upper part of the processing tank 42 and is higher than the upper edge of the side wall 44 of the processing tank 42.
And an outer tank 48 having the same.

A pure water supply pipe 52 having a flow control valve 50
Is connected to the bottom of the processing tank 42 to supply pure water to the processing tank 42, and a chemical supply pipe 56 having a flow control valve 54.
Is a pure water supply pipe 5 between the flow control valve 50 and the processing tank 42.
2 to supply a chemical solution to the processing tank 42. Outer tub 48
A drain pipe 58 is connected to the bottom of. Processing tank 42
At the bottom, a rectifying plate 60 having a large number of through-holes with a uniform distribution or a non-uniform distribution is provided, and the processing tank 42 is provided via a pure water supply pipe 52 and a chemical supply pipe 56. The pure water or the chemical supplied to the bottom is dispersed in the processing tank 42 with a uniform undisturbed flow. Cleaning device 40 of the present embodiment
In this example, a stirring nozzle as provided in the conventional cleaning apparatus 10 is not provided.

Embodiment of Cleaning Method This embodiment is an example of an embodiment of a method for cleaning a wafer according to the present invention, in which a cleaning apparatus 40 is used to clean a wafer. With reference to FIGS. 2 and 3, a method of cleaning a wafer according to the present embodiment will be described. FIG. 2 (a), (b)
FIGS. 3C and 3D are schematic cross-sectional views of the apparatus showing the state of the cleaning apparatus 40 in each step for explaining the wafer cleaning method of the present embodiment. First, as shown in FIG. 2A, the flow control valve 56 is closed, while the flow control valve 50 is opened, and pure water is supplied to the treatment tank 42 through the pure water supply pipe 52 to fill the processing tank 42 with water. To After filling, the flow control valve 50
Is closed. Next, as shown in FIG. 2B, the wafer W is immersed in pure water, and then the flow rate control valve 56 is opened to supply a chemical solution to the processing tank 42 through a chemical solution supply pipe 54, thereby performing processing. The pure water in the tank 42 is replaced with a chemical. At this time, the pure water in the processing tank 42 overflows from the upper part of the processing tank 42, flows into the outer tank 48, and is drained to the outside via the drain pipe 58.

Subsequently, when the concentration of the chemical in the entire area of the processing tank 42 reaches a predetermined concentration, as shown in FIG. 3C, the flow control valve 56 is closed to stop the supply of the chemical, and Move to In the chemical treatment, the wafer W is immersed in the chemical for a predetermined time. After performing the chemical treatment for a predetermined time, FIG.
As shown in (d), the flow control valve 50 is opened, pure water is supplied to the processing tank 42 via the pure water supply pipe 52, and the chemical in the processing tank 42 is replaced with pure water. At this time, the processing tank 42
The chemical solution inside overflows from the upper part of the processing tank 42, flows into the outer tank 48, and is discharged to the outside via the drain pipe 58. By maintaining this state for a predetermined time, the rinse cleaning of the wafer W with pure water is completed.

Hereinafter, the effects of the cleaning method of this embodiment will be described with reference to FIGS. FIG. 4 shows the slowness of the replacement speed of the pure water by the chemical solution for each wafer region when the pure water is replaced by the chemical solution, and FIG. 5 shows the slowness of the replacement speed of the chemical solution by the pure water for each wafer region when the chemical solution is replaced by the pure water. Is shown. At the time of the replacement of the pure water with the chemical, as shown in FIG. 4, the replacement speed of the pure water with the chemical slows down for each wafer region. In the region A located at the central bottom of the cleaning tank 12, the flow rate of the chemical solution is high, so that the pure water is quickly replaced by the chemical solution, and the effect of the chemical solution treatment is increased. On the other hand, in the region C located at the upper part of the periphery of the cleaning tank 12, the flow rate of the chemical solution is slower than that in the region A, so the progress of the replacement with the pure water chemical is slower than in the region A. A is smaller than that of A. The chemical treatment effect in the region B located between the region A and the region C is intermediate between the chemical treatment effect in the region A and the chemical treatment effect in the region C.

At the time of chemical solution replacement with pure water, as shown in FIG. 5, the replacement speed of the chemical solution with pure water slows down for each wafer region. In the region A located at the central bottom of the cleaning tank 12, the flow rate of the pure water is high, so that the chemical solution is quickly replaced by the pure water, and the rinse cleaning effect is correspondingly large.
The effect of chemical treatment is reduced. On the other hand, in the region C located at the upper part of the periphery of the cleaning tank 12, the flow rate of the pure water is slower than that in the region A, so the progress of the replacement of the chemical solution with the pure water is slower than that in the region A. On the contrary, the chemical solution treatment effect is larger than that in the region A. The chemical treatment effect in the region B located between the region A and the region C is intermediate between the chemical treatment effect in the region A and the chemical treatment effect in the region C.

Generally, the specific gravity and the viscosity of the chemical solution and the pure water are close to each other. Therefore, if the flow rate control valves 50 and 56 are adjusted to make the supply flow rates of the chemical solution and the pure water equal, the pure water and the pure water can be used. The behavior of the chemical supplied to the chemical and the behavior of pure water supplied in the chemical are very similar, and the in-plane uniformity of the chemical treatment effect is further improved.

Embodiment 2 of Cleaning Apparatus This embodiment is another example of the embodiment of the single-wafer cleaning apparatus for a wafer according to the present invention. FIG. It is a schematic diagram which shows the structure of a type washing apparatus. As shown in FIG. 6, a single-tank-type cleaning apparatus 62 (hereinafter simply referred to as a cleaning apparatus 62) for a wafer of the present embodiment is different from the embodiment of the present invention except that a chemical liquid supply system is provided in two systems. The same configuration as that of the first cleaning device 40 is provided. The cleaning device 62 according to the present embodiment includes a chemical supply pipe 56 provided with the flow rate control valve 54 of the cleaning device 40 according to the first embodiment as a chemical supply system.
In addition to the above, a flow control valve 64 is provided, and another chemical supply pipe 66 that joins the pure water supply pipe 52 is provided.

When the wafer is cleaned using the cleaning apparatus 62 of the present embodiment, the first chemical solution treatment and the rinsing cleaning are performed according to the wafer cleaning method of the above-described embodiment, and the inside of the cleaning tank 42 is cleaned. In a state full of pure water,
Subsequently, the second chemical treatment and the rinse cleaning can be performed using the chemical supply pipe 66 in the same manner as the first chemical treatment and the rinse cleaning.

Modification of Wafer Cleaning Method The cleaning apparatus 40 of the first embodiment and the cleaning apparatus 62 of the second embodiment are provided with flow control valves in the pure water supply system and the chemical solution supply system, respectively. And the supply flow rate of the chemical solution can be adjusted. By adjusting the flow rates of the chemical solution and pure water simultaneously and supplying them to the cleaning tank 42,
A high concentration pure chemical which is not diluted with pure water can be used as the chemical.

[0026]

According to the method of the present invention, a wafer is immersed in pure water in a cleaning tank, and then a chemical is supplied to replace the pure water in the cleaning tank with the chemical while overflowing the pure water. When the water is replaced with the chemical, the supply of the chemical is stopped, and the chemical treatment is performed for a predetermined time. Then, pure water is supplied to replace the chemical in the cleaning tank with pure water while overflowing the chemical. In the method of the present invention, by supplying the chemical solution to the cleaning tank through the replacement with the chemical solution of pure water, the wafer is given an in-plane non-uniformity of the chemical solution treatment effect opposite to the pure water rinsing in which the chemical solution is replaced with pure water. As a result, the wafer can be subjected to the in-plane uniform chemical liquid treatment. Further, the present invention realizes an optimum cleaning apparatus for performing the method of the present invention. According to the method of the present invention and the apparatus of the present invention, it is possible to perform a uniform chemical treatment on the wafer, so that the cleaning ability of the wafer can be improved and the product yield can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a single-tank type cleaning apparatus for a wafer according to a first embodiment.

FIGS. 2A and 2B are schematic cross-sectional views of the apparatus showing states of a cleaning apparatus in respective steps for describing a method of cleaning a wafer according to an embodiment.

FIGS. 3 (c) and (d) are FIGS.
FIG. 5B is a schematic cross-sectional view of the apparatus showing the state of the cleaning apparatus in each step for explaining the wafer cleaning method of the embodiment example, following FIG.

FIG. 4 shows a slow rate of replacement of pure water with a chemical solution for each wafer region during replacement of pure water with a chemical solution.

FIG. 5 shows a slow rate of replacement of a chemical solution with pure water for each wafer region when the chemical solution is replaced with pure water.

FIG. 6 is a schematic view illustrating a configuration of a single-tank type cleaning apparatus for a wafer according to a second embodiment.

FIG. 7 is a schematic diagram showing a configuration of a conventional single-tank type cleaning apparatus for a wafer.

8 (a), (b) and (c) are respectively
It is a typical sectional view of an apparatus showing the state of a cleaning device in each process for explaining a conventional wafer cleaning method.

[Explanation of symbols]

10: Conventional single-tank type wafer cleaning apparatus, 12: Processing tank, 14: Side wall of processing tank, 16: Outside wall, 18 ...
Outer tank, 20 ... On-off valve, 22 ... Pure water supply pipe, 24 ...
On-off valve, 26 ... Chemical supply pipe, 28 ... Drain pipe, 30 ...
... Rectifier plate, 32 ... Stirring nozzle, 40 ... Embodiment 1
Single-wafer cleaning apparatus for wafers, 42 ... Processing tank, 44 ...
Side wall 46 Outer wall 48 Outer tank 50 Flow control valve 52 Pure water supply pipe 54 Flow control valve 56
…… Chemical solution supply pipe, 58 …… Drain pipe, 60 …… Rectifier plate, 6
2. Single-wafer cleaning apparatus for wafer of Example 2 64
... Flow control valve, 66 ... Chemical supply pipe.

Claims (4)

[Claims] 1. A wafer is subjected to chemical treatment using a single-tank type cleaning apparatus having a single cleaning tank in which a chemical solution and pure water are supplied from the bottom and overflowed from the top, and then rinsed with pure water. A method of supplying pure water to a cleaning tank to fill it with water, a step of immersing the wafer in pure water of the cleaning tank, and a step of supplying a chemical solution to overflow the pure water. Replacing the pure water in the chemical solution with the chemical solution, stopping the supply of the chemical solution when the pure water is replaced with the chemical solution, performing the chemical solution treatment for a predetermined time, supplying the pure water and causing the chemical solution to overflow. And replacing the chemical in the cleaning tank with pure water. 2. The method according to claim 1, further comprising the step of supplying pure water to the cleaning tank for a predetermined time after the chemical solution in the cleaning tank is replaced with the pure water, and rinsing the wafer with the pure water. Item 3. The method for cleaning a wafer according to Item 1. 3. A single-tank type cleaning apparatus for supplying a chemical solution and pure water from a bottom portion and overflowing from a top portion, and for cleaning a wafer in the cleaning bath. It is provided with a pure water supply means for supplying pure water to the cleaning tank provided with a flow rate adjusting mechanism for adjusting, and a chemical liquid means for supplying a chemical liquid to the cleaning tank with a flow rate adjusting mechanism for adjusting the flow rate of the chemical liquid. A single-wafer cleaning apparatus for a wafer, comprising: 4. The single-wafer cleaning apparatus according to claim 3, wherein a plurality of chemical liquid supply means are provided, each supplying a different type of chemical liquid.