JPH06196466A - Wafer cleaning device - Google Patents

Abstract

PURPOSE:To prevent fine particles from a standing in a cleaning tank so as to efficiently clean a wafer. CONSTITUTION:A diffusion plate 17 is disposed inside a cleaning tank 12, a flow of cleaning liquid is set larger in flow rate at the center region of a diffusion plate 17 where a wafer is arranged than that at the peripheral region of the plate 17, through-holes are formed in slits, and the slits are alternately arranged. By this setup, flows of cleaning liquid jetted out through the slits 19a, 19b, and 19c grow laminar flow, so that fine particles are prevented from standing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer cleaning apparatus used in a semiconductor manufacturing process.
The present invention relates to a wafer cleaning device capable of preventing fine particles from staying in a cleaning tank and efficiently removing contaminants.

[0002]

2. Description of the Related Art One of the most basic techniques in a semiconductor wafer process is a cleaning technique. While the wafer process itself has many elemental technologies, it can be said that the cleaning technology is, so to speak, an essential step that connects them.

In recent years, miniaturization of circuit patterns has advanced, and LS
As I becomes highly dense, highly integrated, and has a multi-layer structure, microcontamination represented by particles and metal impurities has a great influence on the yield and reliability of products.

Therefore, in the semiconductor wafer process, the importance of cleaning is becoming more important. Among the cleaning technologies, the wet cleaning process plays a central role in removing contamination from the previous process and supplying a clean wafer to the process after cleaning. Impurities that must be controlled in this wet cleaning process are various such as adsorbed organic substances, heavy metals, and natural oxide films, but fine particles (particles) are the most difficult object to be removed, and the particles of fine particles that must be removed in the future. The diameter becomes smaller and smaller.

As a conventional wafer cleaning apparatus, the one shown in FIG. 8 is known. This device is a container-like cleaning tank 1
A cleaning liquid supply pipe 2 is connected to the center of the bottom of the cleaning liquid (chemical liquid, pure water, etc.) a at a predetermined flow rate. Then, the cleaning liquid a introduced is the flat dispersion plate 3
And is dispersed in the cleaning tank 1 and flows upward through the plurality of flow holes 4a of the diffusion plate 4 disposed in the lower portion of the cleaning tank 1 to clean the plurality of wafers 5 stored in the carrier (not shown).
The flow holes 4a are evenly formed in the diffusion plate 4.

[0006]

However, since the plurality of through holes 4a of the diffuser plate 4 of the above-mentioned conventional apparatus are uniformly opened, in the region where the wafers 5 to 5 are arranged above the diffuser plate. However, even if the cleaning liquid is discharged at the same flow velocity as the flow holes in the other regions, there is a flow resistance of the wafer or the like, and the flow velocity declines, so that the wafer cleaning effect cannot be sufficiently obtained.

Further, as shown in FIG. 7, since the cleaning liquid discharged from the flow hole 4a is a thin flow, it is easily attenuated and there is a problem that the upper part of the wafer cannot be cleaned. In addition, since a turbulent flow is generated between the cleaning liquid flows discharged from the adjacent flow holes 4a, 4a, the cleaned fine particles are stagnated in this turbulent flow region, which causes a problem that the particle removal efficiency is reduced. ing. For this reason, there is a problem that the fine particles in the bath are re-attached to the wafer while remaining, leading to the occurrence of pattern defects in a later process. Further, even when the liquid is switched from the chemical liquid to the pure water, the large number of turbulent flows described above deteriorate the liquid switching efficiency, and the chemical liquid in the previous step (for example, hydrofluoric acid solution, etc.) regardless of the pure water cleaning. ) Remains, and there is a problem that it is affected by the remaining chemical solution such as being locally etched. When the inflow pressure is not buffered, regions with different inflow pressures appear in the cleaning tank, and in the region with low inflow pressure, the cleaning ability is deteriorated due to chemical liquid substitution characteristics, particle removal effect, retention in the cleaning tank, etc. Have a problem that causes

In order to solve such a problem, if the flow velocity of the cleaning liquid discharged from each circulation hole 4a is increased,
In the future, there will be a problem that the wafer 5 will oscillate (dance), and chipping (chipping) of the wafer will cause dust to be generated.

The present invention was devised in view of such conventional problems, and an object of the present invention is to prevent retention of fine particles in a bath and to enable efficient wafer cleaning. It is to provide a wafer cleaning device that does.

[0010]

According to the invention of claim 1 of the present application, the cleaning liquid is supplied from the bottom of the cleaning tank, and the cleaning liquid is supplied through a plurality of flow holes of a diffusion plate disposed in the cleaning tank. In a wafer cleaning device in which a cleaning liquid flows out upward and a plurality of wafers arranged in parallel to each other are cleaned, a plurality of rows of slit groups parallel to a wafer surface are formed in a wafer arrangement area in the center of the diffusion plate. The slits in the rows adjacent to each other are arranged alternately, and the flow rate per unit area of the wafer placement area of the diffusion plate is larger than the flow rate per unit area of the area other than the wafer placement area. The setting is a solution, and the above-mentioned object is achieved by this configuration.

The invention according to claim 2 of the present application is characterized in that a dispersion plate is provided below the diffusion plate to uniformly distribute the cleaning liquid supplied from the bottom of the cleaning tank to the lower surface of the diffusion plate. This configuration achieves the above object.

[0012]

In the invention according to claim 1 of the present application, since the slit formed in the wafer arrangement area at the center of the diffusion plate is parallel to the wafer surface, the cleaning liquid discharged upward from the slit becomes a laminar flow. Has the effect of cleaning along the wafer surface. In particular, since the slits of the slit groups in the adjacent rows are arranged in an alternating manner, there is an effect of suppressing the turbulent flow generated between the slit groups in the adjacent rows, the retention of fine particles Can be prevented.

Further, by alternately arranging the wafers in this way, it is possible to prevent a reduction in the contact flow rate of the cleaning plate to the front and back surfaces of the wafer when the wafer arrangement direction (direction) is deviated. Then, by setting the flow rate of the cleaning liquid per unit area of the wafer arrangement area of the diffusion plate to be larger than that in the area other than the wafer arrangement area, there is an action of extending the distance until the attenuation of the laminar flow discharged from the slit, It is possible to clean the upper part well. Further, by arranging the slit groups in a plurality of rows, the wafer is held between the laminar flows discharged from the slit groups in the two rows, so that the swing of the wafer is suppressed and the generation of dust due to chipping of the wafer occurs. To be prevented.

According to the second aspect of the present invention, in addition to the above action, in order to make the fluid pressure of the cleaning liquid reaching the lower surface of the diffusion plate uniform, the flow rate of the cleaning liquid can be changed by changing the shape and size of the flow hole. It becomes possible to adjust.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the invention according to the present application will be described below with reference to the embodiments shown in the drawings.

FIG. 1A is a sectional view of the wafer cleaning apparatus of this embodiment, and FIG. 1A is a plan view of the diffusion plate.

In the figure, reference numeral 11 is a wafer cleaning device, and a cleaning liquid supply pipe 1 is provided at the center of the bottom of a cleaning tank 12 having a substantially cubic container shape.
3 are connected and connected. Above the cleaning liquid supply port 14 at the bottom of the cleaning tank 12, two parallel dispersion plates 15 and 1 are provided.
6. Further, a diffusion plate 17 is arranged above it. The two dispersion plates 15 and 16 have a large number of holes 15a and 16a.
Are uniformly opened, and the holes 15a and 16a are opened at positions displaced from each other so that they do not match when the both dispersion plates 15 and 16 are superposed. For this reason,
The inflow pressure of the cleaning liquid passing through both dispersion plates 15 and 16 is relaxed and reaches the lower surface of the diffusion plate 17 with a uniform inflow pressure.

The diffusion plate 17 is arranged so as to define the cleaning tank 12 in two upper and lower parts, and a large number of circulation holes are opened. The flow holes are divided into two types, and as shown in FIG. 1B, there are a small-diameter circular hole 17a opened in the peripheral portion and slits 19a, 19b, 19c in the central wafer arrangement region. In the present embodiment, the circular holes 18 in the peripheral portion are intermittently arranged in two rows along the peripheral edge of the diffusion plate 17. As shown in FIG. 3B, the slits formed in the wafer placement area at the center of the diffusion plate 17 are arranged in a line adjacent to a slit group consisting of three slits 19a, 19c, and 19a on a straight line. A group of slits composed of the main slits 19b, 19b was arranged, and the slits forming both rows were alternately arranged so as to be staggered. By repeatedly forming such an array, as shown in FIG. 1B, the wafers 20a arranged in the row direction are sandwiched by the laminar flow of the cleaning liquid a from the two rows of slit groups. When this state is viewed from one side surface of the wafer, it becomes as shown in FIG. The width of each slit is set so that slit 19c> slit 19a> slit 19b in this embodiment.

As described above, the laminar flow discharged from each slit produces little turbulent flow between the slits in the same row as shown in FIG. 2, so that the retention of fine particles can be suppressed. In the adjacent slit group, the flow rate in the row having the three slits 19a, 19c, 19c is larger than that in the row having the two slits 19b, 19b, so that the wafer in the carrier has front and back surfaces. Since the wafer is held on one side, it is possible to prevent the wafer from swinging.

Further, for example, the wafer 20b shown in FIG.
When the slits are arranged in a slanted line as shown in FIG.
Since the b and slits 19c effectively eject the cleaning liquid onto both surfaces of the wafer 20b, the cleaning effect does not deteriorate in this case as well. Since the wafer is normally arranged above the diffusion plate 17, the cleaning flow discharged from each slit is an integrated laminar flow slightly above the slit, and both surfaces of the wafer are uniformly cleaned. .

As described above, since the flow rate in the wafer placement area in the center of the diffusion plate is larger than that in the periphery, even if carriers (workpieces) containing a plurality of wafers are placed and the flow resistance increases, the laminar flow is increased. It is possible to suppress the attenuation of the circulation pressure of. Therefore, cleaning up to the upper part of the wafer can be effectively performed.

FIG. 3 shows a modified example of the dispersion plate. A plurality of dispersion plates 21 are radially arranged above the cleaning liquid supply port 14 at the center of the bottom of the cleaning tank 12 to distribute the flow rate of the cleaning liquid. Here is an example.

Further, as shown in FIG. 4, the slit groups formed on the diffusion plate 17 may be connected to adjacent slit groups in a zigzag shape, and the slits 19d, 19
e and 19f are the slits 19a, 19b and 1 of the above embodiment.
It corresponds to 9c.

Further, FIGS. 5A and 5B show another modification of the dispersion plate, which has two dispersion plates 22 and 23 similar to the above-mentioned embodiment and is arranged on the upper side. The dispersion plate 23 is
The area is smaller than that of the dispersion plate 22 arranged on the lower side. Further, holes 22a and 23a are formed in both dispersion plates 22 and 23 at the same pitch, and when they are arranged in the cleaning tank 12, they are arranged so that the holes 22a and 23a do not overlap each other. In this way, the dispersion plate 2 arranged above
When the area of 3 is made small, when a chemical solution or pure water is injected into the cleaning tank 12, the cleaning solution supply port 1 at the bottom center of the cleaning tank 12
It is possible to sufficiently buffer the inflow pressure immediately above 4 and make it easy for the cleaning liquid flow to reach the peripheral edge of the diffusion plate 17. For this reason, the inflow pressure passing through each hole of the diffusion plate 17 is made uniform, so that a laminar flow is easily obtained above the diffusion plate 17. By forming a uniform laminar flow in the cleaning tank, the cleaning liquid replacement characteristic and the cleaning ability are improved, which greatly contributes to cleaning the object to be cleaned such as a wafer.

FIG. 6 shows another modification of the dispersion plate.
In the figure, reference numeral 24 denotes a substantially cylindrical dispersion plate, and a plurality of (8 in this example) semi-elliptical notches 24a are formed in the peripheral wall portion. As shown in FIG. 6, this dispersion plate 24 has a cleaning tank 12
By arranging the cleaning liquid supply port 14 at the center of the bottom face down, the top plate portion 24b of the dispersion plate 24 can buffer the inflow pressure of the cleaning liquid and the notch 24a can disperse the cleaning liquid.

Although the present embodiment has been described above, the invention according to the present application is not limited to this, and various design changes accompanying the gist of the configuration can be made.

[0027]

According to the invention described in claims 1 and 2 of the present application, there is an effect that fine particles and the like are prevented from staying in the cleaning tank, and efficient removal of contamination without chipping of a wafer is possible. Similarly, since the chemical solution can be prevented from staying in the tank, there is an effect that the chemical solution cleaning can be efficiently switched to the pure water cleaning. Therefore, the amount of pure water used can be significantly reduced.

Further, since the slits are arranged alternately, a sufficient flow can be given between the inclined wafers, and the cleaning uniformity between the surfaces can be improved.

Further, the cleaning liquid is, for example, a large-scale circulation filtration (20 liters / liter) of a highly viscous chemical liquid such as sulfuric acid / hydrogen peroxide or hot phosphoric acid
(More than a minute) has the effect that it is possible to handle.

[Brief description of drawings]

1A is a sectional view of an embodiment of the present invention, and FIG. 1B is a plan view of a diffusion plate.

FIG. 2 is an explanatory diagram of an embodiment of the present invention.

FIG. 3 is a sectional view of a modification of the dispersion plate.

FIG. 4 is a plan view of a modified example of the diffusion plate.

5A is a cross-sectional view showing a modified example of the dispersion plate, FIG.
Is a plan view of the dispersion plate.

FIG. 6 is a perspective view showing another modified example of the dispersion plate.

FIG. 7 is an explanatory diagram of a conventional example.

FIG. 8 is a sectional view of a conventional example.

[Explanation of symbols]

 a ... Cleaning liquid 11 ... Wafer cleaning device 12 ... Cleaning tank 13 ... Cleaning liquid supply pipe 14 ... Cleaning liquid supply port 15, 16 ... Dispersion plate 17 ... Diffusion plate 18 ... Circular holes 19a, 19b, 19c ... Slit 20 ... Wafer

Claims (2)

[Claims] 1. A cleaning liquid is supplied from the bottom of a cleaning tank, and the cleaning liquid flows upward through a plurality of flow holes of a diffusion plate disposed in the cleaning tank, and the cleaning liquid is arranged in parallel with each other. In a wafer cleaning apparatus for cleaning a plurality of wafers, in the wafer arrangement area at the center of the diffusion plate, a plurality of rows parallel to the wafer surface, slit groups are opened, and the slit groups of adjacent rows are alternately formed. A wafer cleaning apparatus, wherein slits are arranged and a flow rate per unit area of a wafer placement region of the diffusion plate is set to be larger than a flow rate per unit area of a region other than the wafer placement region. 2. The wafer cleaning apparatus according to claim 1, further comprising a dispersion plate below the diffusion plate, the dispersion plate allowing the cleaning liquid supplied from the bottom of the cleaning tank to evenly flow to the lower surface of the diffusion plate.