JPH09199462A - Wafer cleaning method and apparatus therefor - Google Patents

Abstract

Kind Code: A1 Abstract: A wafer cleaning method and apparatus for cleaning the wafer back surface immediately before stepper exposure, and preventing defocus due to particles on the wafer back surface during stepper exposure. In a wafer cleaning method, a rotation shaft 32 is located above a wafer 21, and a resist removal portion on the wafer front surface is chucked from the upper portion of the wafer 21 so that the back surface of the wafer 21 can be cleaned immediately before stepper exposure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer cleaning method and apparatus, and more particularly to a wafer cleaning method and apparatus for cleaning the back surface of a semiconductor wafer.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
For example, there are the following. FIG. 5 is a schematic plan view showing such a conventional wafer cleaning apparatus, and FIG. 6 is a view showing a wafer set state in the wafer cleaning apparatus.

As shown in FIG. 5, a conventional wafer cleaning apparatus 1 includes five units such as a transfer unit 2, a first reversing unit 3, a back surface cleaning unit 4, a second reversing unit 5, and a front surface cleaning unit 6. It is configured. Of these, three pairs of left and right support arms 7 for grasping the wafer in the transfer unit 2 are provided, and the first and second reversing units 3 and 5 have a reversing mechanism for reversing the wafer. 8 and 9 are provided.

Further, the back surface cleaning unit 4 is equipped with a cleaning brush 10, and the front surface cleaning unit 6 is equipped with a cleaning brush 11. When only the back surface cleaning of the wafer is performed by the wafer cleaning apparatus 1, first, the wafer that has been processed in the previous step is transferred by the transfer unit 2 and set in the first reversing unit 3. In the first reversing unit 3, the wafer is positioned based on the notch (or orientation flat) of the wafer, and the reversing mechanism 8 reverses the wafer.

Next, the wafer is set in the back surface cleaning unit 4 by the transfer unit 2. In the wafer set, the wafer 12 is placed on the positioning pins 13 as shown in FIG. The positioning pin 13 is connected to the stage 14 and is rotated by the motor 15. Backside cleaning unit 4
Then, while rotating the wafer 12 at a predetermined rotation speed, the cleaning brush 10 is pressed against the back surface of the wafer 12 to clean the back surface of the wafer 12. In cleaning the wafer 12, the cleaning liquid is supplied to the cleaning brush 10, and when the cleaning operation is completed, the wafer 12 is rotated at a high speed and drained and dried.

[0006]

However, in the conventional wafer cleaning apparatus 1 described above, when the wafer after resist coating is cleaned, particles and the like adhering to the upper surface (back surface) of the wafer are removed from the peripheral portion of the wafer to the lower surface. There is a possibility that particles may be generated because the cleaning liquid is contaminated on the resist-coated surface and contaminates the resist-coated surface, and the cleaning liquid also adheres to the resist-coated surface. Therefore, the wafer back surface was not cleaned after the resist coating.

Therefore, when the wafer chuck of the resist coating apparatus is dirty, particles adhere to the back surface of the wafer, and during the stepper exposure in the next step, the particles rise due to the influence of the particles, resulting in defocusing during exposure. Was the cause of. SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above problems and provide a wafer cleaning method and an apparatus therefor capable of cleaning the wafer back surface immediately before stepper exposure and preventing defocus due to particles on the wafer back surface during stepper exposure. And

[0008]

In order to achieve the above object, the present invention provides: [1] In a method for cleaning a wafer, a rotating shaft is located above the wafer, and a resist removal portion on the wafer surface is chucked from the above wafer. However, the back surface of the wafer can be cleaned immediately before the stepper exposure.

[2] In a wafer cleaning apparatus, a wafer chuck having a vacuum suction groove and a rotation shaft positioned above the wafer surface, a means for performing vacuum suction from the vacuum suction groove, and the rotation. And means for driving the shaft. [3] In the wafer cleaning method, a step of setting a wafer having a resist-removed portion on the surface of the wafer which has been subjected to the pretreatment step in the surface cleaning unit by a transfer unit, and a step of cleaning the wafer surface by the wafer surface cleaning unit, The step of setting the wafer whose wafer surface has been cleaned in the wafer back surface cleaning unit by the transfer unit, the rotation axis is located above the wafer, and the resist removal portion of the wafer surface from the above wafer is chucked by the stepper. Immediately before exposure, a step of enabling cleaning of the back surface of the wafer is performed.

[4] In a wafer cleaning apparatus, a wafer transfer unit, a wafer surface cleaning unit for cleaning the surface of a wafer having a resist removal portion on the wafer surface after a pretreatment process, and a resist removal portion on the wafer surface And a wafer back surface cleaning unit for cleaning the back surface of the wafer.

With the above structure, [A] (1) Even if the wafer after resist application is cleaned, since the resist surface is protected by the wafer chuck, particles and the like adhere to the resist surface during cleaning. Never.

(2) Since the wafer chuck does not contact the resist, the wafer surface is not scratched. (3) Since the wafer reversing unit is not required, the installation space for the entire wafer cleaning apparatus can be small. (4) The back surface of the wafer can be cleaned after resist application, and contaminants can be removed even if the wafer chuck of the resist application apparatus is dirty, so that defocusing at the stepper exposure in the next step can be prevented.

[B] (1) Wafer front surface cleaning-Wafer back surface cleaning is possible without a reversing unit, and the space for the entire apparatus is small. (2) Since the front surface cleaning is performed before the back surface cleaning, particles in the wafer suction portion of the wafer front surface edge are removed, and the vacuum suction groove in the back surface cleaning unit can be prevented from being contaminated.

Therefore, the contamination of other wafers can be avoided.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 is a partially cutaway front view of a wafer chuck of a wafer cleaning apparatus showing a first embodiment of the present invention, FIG. 2 is a bottom view of the wafer chuck, FIG. 3 is a front view of a wafer to be cleaned, and FIG. It is a partial cross section figure of a wafer.

Similar to the conventional wafer cleaning apparatus, the wafer which has been processed in the previous step is transferred to the back surface cleaning unit by the transfer unit. As shown in FIGS. 1 and 2, when the wafer 21 is transferred, the wafer 21 is held by the wafer chuck 31.
Is adsorbed on. Wafer contact surface 33 of wafer chuck 31
A vacuum suction groove 34 is formed in the vacuum suction groove 34, and the vacuum suction groove 34 passes through the rotary shaft 32 of the wafer chuck 31 and is vacuum suctioned.

As shown in FIGS. 3 and 4, a resist 22 is applied on the wafer 21 in the previous step. Wafer 2
The resist 22 on the wafer 1 has a predetermined width A, for example, about 5 mm, and the resist around the wafer is removed over the entire circumference of the wafer after the resist is applied by the resist applying apparatus in the previous step. The wafer contact surface 33 of the wafer chuck 31 is adapted to attract the resist-removed portion 23.
As shown in FIG. 1, the width B of the wafer chuck 31 that adsorbs the portion 23 of the wafer 21 from which the resist 22 has been removed.
Is, for example, about 3 mm.

When the wafer 21 is attracted to the wafer chuck 31, the wafer chuck 31 rotates at a predetermined rotation speed,
The adsorbed wafer 21 also rotates in the same manner. When the wafer 21 rotates as in the conventional method, the cleaning brush 35 is pressed against the back surface of the wafer 21 to clean the back surface of the wafer. In cleaning the wafer, a cleaning liquid, for example, pure water, is supplied to the cleaning brush 35 as in the conventional method.

When the cleaning operation is completed, the wafer 21 is rotated at a high speed to drain and dry the wafer 21, and the cleaning of the back surface of the wafer is completed. As described above, according to this embodiment, (1) even if the wafer after resist application is cleaned, the resist surface is protected by the wafer chuck, so that particles or the like do not adhere to the resist surface during cleaning.

(2) Since the wafer chuck does not come into contact with the resist, the wafer surface is not scratched. (3) Since the wafer reversing unit is not required, the installation space for the entire cleaning apparatus can be small. (4) The back surface of the wafer can be cleaned after resist application, and contaminants can be removed even if the wafer chuck of the resist application apparatus is dirty, so that defocusing at the stepper exposure in the next step can be prevented.

Next, a second embodiment of the present invention will be described. 7 is a flowchart of a wafer cleaning method showing a second embodiment of the present invention, FIG. 8 is a top view of a front surface cleaning unit of the wafer, and FIG. 9 is a partially cutaway front view of a back surface cleaning unit of the wafer. The wafer cleaning apparatus of this embodiment includes a transfer unit, a front surface cleaning unit, and a back surface cleaning unit. Like the conventional apparatus, the transfer unit is provided with a pair of left and right indicating arms for grasping a wafer, and the back surface cleaning unit. Is equipped with a cleaning brush, and the surface cleaning unit is also equipped with a cleaning brush.

The operation of the wafer cleaning apparatus will be described. (1) First, the wafer 45, which has been processed in the previous step, is transferred to the surface cleaning unit by the transfer unit (step S1). (2) Next, the wafer surface cleaning unit cleans the wafer surface. For example, as shown in FIG. 8, the wafer 45 is set on a wafer chuck 41 having a peripheral wafer contact surface 42 and a vacuum suction groove 43 formed, and after cleaning is completed, the wafer 45 is drained by high speed rotation. Drying is performed (step S2).

(3) Next, the wafer 4 is transferred by the transfer unit.
5 is conveyed and set in the wafer back surface cleaning unit (step S3). (4) Next, the back surface of the wafer 45 is cleaned by the same wafer cleaning unit as the wafer cleaning apparatus of the first embodiment (step S4). That is, as shown in FIG. 9, when the front surface of the wafer 45 is sucked by the wafer chuck 51 having the rotating shaft 52, the contact surface 53 to the wafer, and the vacuum suction groove 54, the wafer 45 is rotated and the back surface is cleaned. To do. After the washing is completed, it is drained and dried by high speed rotation.

FIG. 10 is a top view of a mask front surface cleaning unit showing a third embodiment of the present invention, and FIG. 11 is a partially cutaway front view of the mask back surface cleaning unit. In addition, in the above-mentioned embodiment, the example applied to the wafer cleaning has been described.
In this embodiment, as shown in FIGS. 10 and 11, the wafer chuck structure is changed so that it is used for mask cleaning.

That is, in FIG. 10, the mask surface cleaning unit 60 has a mask chuck 61, a vacuum suction groove 63 is formed on a mask contact surface 62 of the mask chuck 61, and a mask 65 is set. After the washing is completed, it is drained and dried by high speed rotation. Next, referring to FIG. 11, the pattern-removed portion 66 on the surface of the mask 65.
And a mask back surface cleaning unit 71 for cleaning the back surface of the mask 65 is provided. The mask back surface cleaning unit 71 includes a rotating shaft 72, a mask contact surface 73,
Vacuum suction groove 7 formed on the contact surface 73 to the mask
Four.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0027]

As described above, according to the present invention, the following effects can be obtained. (A) According to the invention of claim 1 or 2, (1) even if the wafer after resist coating is cleaned, since the resist surface is protected by the wafer chuck, particles or the like adhere to the resist surface during cleaning. There is nothing to do.

(2) Since the wafer chuck does not come into contact with the resist, the wafer surface is not scratched. (3) Since the wafer reversing unit is not required, the installation space for the entire cleaning device can be small. (4) The back surface of the wafer can be cleaned after resist application, and contaminants can be removed even if the wafer chuck of the resist application apparatus is dirty, so that defocusing at the stepper exposure in the next step can be prevented.

(B) According to the invention of claim 3 or 4, (1) wafer front surface cleaning-wafer back surface cleaning can be performed without a reversing unit, and the space of the entire apparatus can be small. (2) Since the front surface cleaning is performed before the back surface cleaning, particles in the wafer suction portion of the wafer front surface edge are removed, and the vacuum suction groove in the back surface cleaning unit can be prevented from being contaminated.

Therefore, it is possible to avoid contamination of other wafers. Furthermore, by changing the wafer chuck structure, it can be applied to mask cleaning.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a wafer chuck of a wafer cleaning apparatus showing a first embodiment of the present invention.

FIG. 2 is a bottom view of the wafer chuck of the wafer cleaning apparatus showing the first embodiment of the present invention.

FIG. 3 is a surface view of a wafer to be cleaned showing the first embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of a wafer to be cleaned showing the first embodiment of the present invention.

FIG. 5 is a schematic plan view showing a conventional wafer cleaning apparatus.

FIG. 6 is a diagram showing a set state of wafers in a conventional wafer cleaning apparatus.

FIG. 7 is a flow chart of a wafer cleaning method showing a second embodiment of the present invention.

FIG. 8 is a top view of a wafer surface cleaning unit showing a second embodiment of the present invention.

FIG. 9 is a partially cutaway front view of a wafer back surface cleaning unit showing a second embodiment of the present invention.

FIG. 10 is a top view of a mask surface cleaning unit showing a third embodiment of the present invention.

FIG. 11 is a partially cutaway front view of a mask back surface cleaning unit showing a third embodiment of the present invention.

[Explanation of symbols]

 21, 45 Wafer 22 Resist 23 Part from which resist is removed 31, 41, 51 Wafer chuck 32, 52, 72 Rotation shaft 33 Wafer contact surface 34, 43, 54, 63, 74 Vacuum suction groove 35 Cleaning brush 53 To wafer Contact surface 60 of mask surface cleaning unit 61 mask chuck 62 contact surface to mask 65 mask 66 pattern removal portion of mask surface 71 mask back surface cleaning unit 73 contact surface to mask

Claims (4)

[Claims] 1. A method for cleaning a wafer, wherein (a) a rotation axis is located above a wafer, a resist removal portion of a wafer front surface is chucked from the wafer upper surface, and (b) a wafer back surface can be cleaned immediately before stepper exposure. A method for cleaning a wafer, characterized in that 2. In a wafer cleaning apparatus, (a) a wafer chuck having a vacuum suction groove and a rotating shaft located above the wafer surface, and (b) vacuum suction from the vacuum suction groove. A wafer cleaning apparatus comprising means and (c) means for driving the rotating shaft. 3. A wafer cleaning method comprising: (a) a step of setting a wafer having a resist-removed portion on a wafer surface which has been subjected to a pretreatment step to a wafer surface cleaning unit by a transfer unit; and (b) the wafer surface cleaning unit. And (c) setting the wafer whose wafer surface has been cleaned on the wafer back surface cleaning unit by a transfer unit, and (d) the rotation axis being located above the wafer. And a step of chucking the resist-removed portion on the front surface of the wafer from above and enabling the back surface of the wafer to be cleaned immediately before stepper exposure. 4. A wafer cleaning apparatus comprising: (a) a wafer transfer unit; and (b) a wafer surface cleaning unit for cleaning the surface of a wafer having a resist-removed portion on the surface of the wafer which has undergone a pretreatment process. ) A wafer cleaning apparatus comprising: a wafer back surface cleaning unit that chucks a resist removal portion of the wafer surface and cleans the wafer back surface.