JPH08195370A - Edge cleaning method - Google Patents

Abstract

PURPOSE: To surely remove a coating film on the periphery of a wafer in the shape of a vertical end so as to prevent dust from being formed and to improve the wafer in yield. CONSTITUTION: An edge cleaning method is carried out through such a manner that a wafer W is rotated as attracted to a wafer stage 1, and solvent is spouted out to remove a coating film on the periphery of the wafer W as wide as prescribed, wherein the wafer is changed in rotating speed and acceleration by stages. To put it concretely, it is preferable that following steps are provided, a first step wherein the wafer W is rotated at a high speed, and solvent is spouted out enough in time, a second step wherein the wafer W is rotated at a lower speed than that in the first step, and solvent is spouted out for a shorter time than that in the first step, and a third step wherein the wafer W is rotated at a higher speed than that in the first step, and no solvent is spouted out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge cleaning method for removing an outer peripheral coating film on a wafer surface with a solvent.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, an SOG (Spin-on-Glass) layer is formed on a wafer for flattening an interlayer insulating film
The film is applied. The SOG coating is performed by a spin coating process of dropping a chemical solution called a source in which SiO _X is dissolved in alcohol while the wafer is attracted and rotated by a wafer chuck. When the edge portion of the surface of the wafer comes into contact with the positioning portion or the like in each step, dust is generated due to the lack of the coating film (resist). In order to prevent this, an edge clean (edge rinse) for removing the outer peripheral coating film on the wafer surface with a solvent is required. This edge clean is usually performed when the coating film is applied. In the conventional edge clean, the organic solvent is injected from a nozzle located above the outer peripheral portion of the wafer while rotating the wafer at a constant speed, and the coating film on the outer peripheral portion of the wafer is removed in one step.

[0003]

However, in the above-mentioned conventional edge cleaning method, depending on the combination of the coating film material and the organic solvent (for example, organic SOG and cyclohexanone), the edge of the wafer outer peripheral portion after the coating film is removed. In some cases, the coating film could not be properly removed because the shape of the part had a hem or a mountain-shaped bulge. These defects are:
Since edge cleaning was performed in one step with a low-speed rotating wafer, it was caused by physical indentation at the initial stage of solvent injection or swelling due to incorporation of the solvent into the coating film. Therefore, in the conventional edge clean performed in one step, for example, in the case of the combination of the organic SOG and cyclohexanone, it is not possible to obtain a proper vertical end shape, and there is a problem that it becomes a particle generation source. The present invention has been made in view of the above circumstances, and an object thereof is to provide an edge cleaning method capable of reliably removing a coating film on the outer peripheral portion of a wafer with a vertical end shape, and to prevent dust generation.

[0004]

According to the edge cleaning method of the present invention for achieving the above object, a wafer is adsorbed on a wafer stage and rotated, and at the same time, a solvent is injected to keep a coating film on a peripheral portion of the wafer constant. In the edge cleaning method of removing only the width, the rotation speed and acceleration of the wafer are changed stepwise. Then, the edge cleaning method includes the first step of rotating the wafer at a high speed and injecting the solvent in a sufficient time,
A second step of rotating the wafer at a lower speed than the rotation of the first step and performing a solvent injection for a shorter time than the first step; and a second step of rotating the wafer at a higher speed than the rotation of the first step without injecting the solvent. It is preferable to include 3 steps.

[0005]

By changing the wafer rotation speed and acceleration stepwise, it is possible to control the contact time between the solvent and the coating film, the width of removal of the coating film, and the discharge of the residual solvent. In the first step, high-speed wafer rotation and solvent injection are performed for a sufficiently long time, and the removability is enhanced by the stable wafer rotation movement and the sufficiently long contact time between the solvent and the coating film.
In the second step, low-speed wafer rotation and solvent injection are performed in a short time, and the width of the coating film on the peripheral portion of the removed wafer is widened. Further, the incorporation of the solvent into the coating film is suppressed. In the third step, the injection of the solvent is stopped, the wafer is rotated at high acceleration, the solvent remaining on the wafer is quickly discharged to the outside of the wafer, and the contact time between the residual solvent and the coating film is shortened. The solvent is not taken into the coating film.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the edge cleaning method according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic view of an edge cleaner used in the edge cleaning method of the present invention, and FIG. 2 is a side view of the edge cleaner used in the edge cleaning method of the present invention. A wafer stage (wafer chuck) 1 used in this embodiment is provided with a horizontally fixed disk-shaped chuck body 3, and the chuck body 3 is connected to a stepping motor 5 with a drive support shaft 7.
Driven by A plurality of suction grooves are formed on the upper surface of the chuck body 3, and these grooves are vacuum-sucked by suction means (not shown) through suction holes penetrating the drive support shaft 7. Thereby, the upper surface of the chuck body 3 functions as a vacuum suction surface for sucking the wafer W. An edge cleaner nozzle 9 is arranged on the side of the wafer chuck 1, and the edge cleaner nozzle 9 injects an organic solvent (edge cleaner liquid) onto the wafer W. A coater cup 11 that covers the attracted wafer W is disposed around the chuck body 3, and the coater cup 11 has a function of preventing the coating material from scattering and keeping the atmosphere around the chuck body 3 constant. In the figure, 12 represents the wafer rotation direction.

Next, the operation procedure of the edge clean is shown in FIG.
This will be described with reference to FIG. 3 is a top view showing a first step of edge clean which is an embodiment of the present invention, FIG. 4 is a side view of FIG. 3, and FIG. 5 is a top view showing a second step of edge clean which is an embodiment of the present invention. 6 is a side view of FIG. The edge clean is performed by the operations of step 1 to step 3 after the coating material is dropped and the wafer is rotated for uniformization. An example of the condition setting in each step in that case is as follows.

Step 1: Rotation speed 2000 rpm time 2 sec With edge cleaner liquid injection Step 2: Rotation speed 1700 rpm Acceleration -3000 rpm / sec time 0.3 sec Edge cleaner liquid injection With step 3: Rotation speed 2700 rpm Acceleration 33000 rpm / sec time 2 sec Edge cleaner No liquid injection

First, in the first step shown in FIGS. 3 and 4, high-speed wafer rotation and injection of the edge cleaner liquid 13 are performed for a sufficiently long time. The removability is enhanced by a stable wafer rotation motion due to high speed rotation and a sufficiently long contact time between the edge cleaner liquid 13 and the coating film. This allows
Only the constant width L1 of the coating film S on the outer peripheral portion of the wafer W is reliably removed. However, in this step, at the same time, the edge cleaner liquid 13 is physically pushed into the upper layer of the coating film by dropping the edge cleaner liquid 13 into the coating film on the same principle as the milk crown at the initial stage of injection, and the coating shown in FIG. A bulge 15 is generated at the edge of the film. Further, by setting a sufficiently long injection time, the edge cleaner liquid 13 is taken into the coating film, the end portion of the coating film swells, and a bulge 15 is added.

Then, the second step is entered. In the second step shown in FIGS. 5 and 6, low speed wafer rotation and injection of the edge cleaner liquid 13 are performed for a short time. This is to remove only the raised portion 15 of the coating film end portion generated in the first step, and by lowering the rotation speed of the wafer W, the width L2 of the coating film S on the peripheral portion of the wafer to be removed is increased. Are using. Further, this step is performed in a short time in order to suppress the swelling 15 at the end portion of the coating film, which occurs due to the above-mentioned incorporation of the edge cleaner liquid 13 into the coating film. As a result, the edge cleaner liquid 13 does not swell to the end of the coating film, and new swelling of the coating film S does not occur.

In the final third step, the injection of the edge cleaner liquid 13 is stopped and the wafer W is rotated at high acceleration. The edge cleaner liquid 13 remaining on the wafer W is rotated by rotating the wafer W at high acceleration.
Is quickly discharged to the outside of the wafer. This shortens the contact time between the residual edge cleaner liquid 13 and the coating film S,
The edge cleaner liquid 13 is suppressed from being taken into the coating film S, and swelling of the end portion of the coating film due to the swelling is prevented. With the above, the operation of the edge clean is completed.

The edge cleaning method according to the present invention is not limited to the above-mentioned embodiment, but may be applied in various ways. For example, the number of revolutions and acceleration in each step can be arbitrarily set as long as the coating film S can be removed. The procedure of the edge cleaning method according to the present invention is
The number of steps need not be three, and may be three or more as long as the content of each step constituting the configuration of the present invention is included.

[0013]

As described above in detail, according to the edge cleaning method of the present invention, the contact time between the solvent and the coating film and the coating film are changed by changing the rotation speed and the acceleration of the wafer stepwise. Since it is possible to control the removal width and the residual solvent discharge, the coating film on the outer peripheral portion of the wafer can be reliably removed with the vertical edge shape, and dust generation due to chipping of the coating film can be prevented. , The product yield can be improved.

[Brief description of drawings]

FIG. 1 is a schematic view of an edge cleaner used in an edge cleaning method of the present invention.

FIG. 2 is a side view of an edge cleaner used in the edge cleaning method of the present invention.

FIG. 3 is a top view showing a first step of edge clean which is an embodiment of the present invention.

FIG. 4 is a side view of FIG. 3;

FIG. 5 is a top view showing a second step of edge cleaning according to the embodiment of the present invention.

FIG. 6 is a side view of FIG. 5;

[Explanation of reference numerals] 1 wafer chuck (wafer stage) 13 solvent L1 coating film removal width in step 1 L2 coating film removal width in step S S coating film W wafer

Claims (2)

[Claims] 1. An edge cleaning method in which a wafer is attracted to a wafer stage and rotated, and a solvent is injected to remove a coating film on a peripheral portion of the wafer by a predetermined width, wherein a rotation speed and an acceleration of the wafer are stepwise. Edge cleaning method characterized by changing to. 2. An edge clean method in which a wafer is attracted to a wafer stage and rotated, and a solvent is injected to remove a coating film on a peripheral portion of the wafer by a predetermined width. In the edge clean method, the wafer is rotated at a high speed and the solvent is injected. A first step that is performed for a sufficient time, a second step that rotates the wafer at a lower speed than the rotation of the first step, and a solvent injection that is shorter than the first step, and a first step that does not perform solvent injection. And a third step of rotating the wafer at a higher speed than the rotation of one step.