JPH0513008Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a centrifugal dryer used in a wafer surface drying process in a series of semiconductor manufacturing processes.

Conventional technology The wafer surface drying process is performed after the cleaning process, which is a pre-process for oxidizing, diffusing, and etching the wafer, or by removing moisture attached to the wafer during the cleaning process after the dicing or grinding process. Therefore, it is performed after the cleaning step.

The centrifugal dryer used in this process rotates a rotary table holding a carrier containing a large number of wafers at high speed in a drying chamber inside an outer cylinder, and uses the resulting centrifugal force and relatively high-speed air flow. Thus, the structure is such that water adhering to the wafer can be shaken off and the entire wafer can be dried.
The above-mentioned high-speed airflow is due to the negative pressure inside the drying chamber caused by the exhaust force of the draft connected to the drying chamber of the centrifugal dryer and the rotation of the rotary table, and this high-speed airflow is efficiently generated. To do this, the outer cylinder of the centrifugal dryer is provided with an air intake port.

However, although centrifugal dryers have traditionally been installed inside clean benches, if the air intake is large, the amount of fine dust that accompanies the air flowing into the drying chamber of the centrifugal dryer increases accordingly. The surface of the wafer during the drying process may become contaminated with the fine dust, leading to deterioration of the characteristics of the resulting semiconductor. Therefore, the size of the air intake port is set as small as possible within a range that can ensure the air flow rate necessary to generate high-speed airflow.

On the other hand, it is necessary to provide the above-mentioned outer cylinder with an opening large enough to allow wafers held on the rotary table to be stored in and taken out from the drying chamber. It is desirable that the size of this opening be as large as possible.

In this way, the above types of centrifugal dryers meet the demands of having a small air intake port to prevent the intrusion of fine dust, and a desire to have a large opening to improve the efficiency of wafer storage and removal. be.

Therefore, in conventional centrifugal dryers, a large diameter opening in the outer cylinder is used to store and take out wafers.
A donut-shaped sub-lid was placed over this opening, and the central opening of the sub-lid was used as an air intake port during rotation of the rotary table (during operation of the centrifugal dryer). according to this,
Both of the above two requirements are satisfied. Further, after the wafer was dried by the centrifugal dryer (while the centrifugal dryer was not in operation), the sub-lid was opened, the wafer was taken out, and then the sub-lid was closed again.

Problems that the invention aims to solve: However, because the secondary lid of conventional centrifugal dryers is donut-shaped, the opening in the center of the secondary lid does not close regardless of whether the centrifugal dryer is in operation or not. It remains open. However, even when the centrifugal dryer is out of operation, the above-mentioned exhaust force in the draft is always acting on the drying chamber, so air constantly flows into the drying chamber, and fine dust can also enter the drying chamber. I couldn't escape it.

Therefore, if this is left unattended, the amount of dust in the drying chamber of the centrifugal dryer will increase, and the wafer will be dried in an atmosphere with a large amount of dust, leaving it in a state where it is likely to get dirty. This may lead to deterioration of the characteristics of the finished semiconductor.

The present invention was made to improve this situation, and it reduces the amount of dust in the drying chamber as much as possible while the centrifugal dryer is in operation, thereby eliminating as much contamination as possible on the wafer during the drying process. The purpose is to eliminate the causes of deterioration of semiconductor characteristics.

Means for Solving the Problems In order to solve the above problems, the centrifugal dryer of the present invention centrifugally dries the cleaned wafers by holding them on a rotary table. When the rotary table is rotating, the air intake is kept open by the negative pressure inside the outer cylinder against the elastic force of the elastic body, and when the rotary table is stopped, the air intake is opened by the elastic force of the elastic body. In that a closing means is provided that operates to close the entrance,
Have a gist.

Effect: According to the above means, when the rotary table is stopped, that is, when the centrifugal dryer is not in use, the air intake port is closed by the closing means, and no fine dust can enter the drying chamber. Therefore, the amount of dust in the drying chamber does not increase while the centrifugal dryer is not operating. Further, while the centrifugal dryer is in operation, the closing means is opened and air is allowed to flow in from the air intake port. Therefore, the wafer can be efficiently dried as in the conventional method.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the centrifugal dryer illustrated in FIG. 1, a rotary table 3 is disposed in a drying chamber 2 within an outer cylinder 1, and this rotary table 3 is driven to rotate at high speed in the direction of arrow A by a drive mechanism 4. It's summery. Further, carrier holding frames 5 are rotatably supported around a horizontal axis 6 at a plurality of locations equally spaced on the outer circumference of the rotary table 3. Further, the drying chamber 2 is communicated with a draft (not shown) through an exhaust duct 7, and the exhaust force of this draft acts on the drying chamber 2 at all times.

An opening 8 having a sufficiently large diameter is formed at the upper end of the outer cylinder 1, and a donut-shaped lid 9 is provided in the opening 8 so as to be openable and closable.

FIG. 1 shows the operating state of the centrifugal dryer, in which a carrier 12 holding a wafer is mounted on a holding frame 5.
is installed. Also, due to the high-speed rotation of the rotary table 3 by the drive mechanism 4 and the effect of the exhaust force of the draft, air flows into the drying chamber 2 through the central opening of the lid 9, that is, the air intake port 13.
Inside, the air flows as a high-speed airflow relative to the wafer, and is then exhausted from the exhaust duct 7 to a draft. Moisture adhering to the wafer, which is rotating at high speed together with the rotary table 3, is shaken off by centrifugal force, and the wafer is dried by the above-mentioned high-speed airflow.

After the drying process has been completed, the wafer is placed in the lid 9 after the centrifugal dryer is stopped (rotation of the rotary table 3 is stopped).
Open it and take it out from drying chamber 2. That is, as shown by the imaginary line in FIG.
The whole wafer is taken out from the opening 8.

After the wafer is removed from the drying chamber 2, the opening 8 of the outer cylinder 1 is closed again with the lid 9. In addition, the air intake port 13, which is the central opening of the lid body 9, is closed by a closing plate 14 shown in phantom lines in the figure to prevent air from flowing into the drying chamber 2 when the centrifugal dryer is not operating. Prevent it.

For example, as shown in FIG. 2, a closing plate 14 disposed on the inner surface of the lid 9 is always urged in a direction to close the air intake port 13 by a compression spring 15, and the exhaust force of the draft is reduced. The structure is such that the negative pressure generated in the drying chamber 2 in cooperation with the rotation of the rotary table causes the closing plate 14 to be sucked downward as shown by the imaginary line in the figure, thereby opening the air intake port 13. It is also possible. In this case, the biasing force of the compression spring 15 is larger than the negative pressure generated in the drying chamber 2 due to the exhaust force of the draft, and the biasing force of the compression spring 15 is larger than the negative pressure generated in the drying chamber 2 due to the exhaust force of the draft and the rotation of the rotary table 3. It is necessary that the pressure be set smaller than the negative pressure generated in the If the biasing force of the compression spring 15 is smaller than the negative pressure generated in the drying chamber 2 by the exhaust force of the draft, the air intake port 13 will remain open even when the centrifugal dryer is not operating. On the other hand, if the negative pressure generated in the drying chamber 2 is greater than the negative pressure generated in the drying chamber 2 due to the cooperation between the exhaust force of the draft and the rotation of the rotary table 3, the air intake port
3 remains closed, and no high-speed airflow is generated in the drying chamber 2.

To restart the centrifugal dryer after it has stopped operating, open the lid 9, hold the carrier 12 on the rotary table 3 through the opening 8 of the outer cylinder 1, and start the drive mechanism to rotate the rotary table 3. Start.

Effects of the invention As mentioned above, the centrifugal dryer of the present invention has a very simple improvement in that the air intake port is left open while the rotary table is rotating and closed when the rotary table is stopped. This makes it possible to minimize contamination of the wafer during the drying process. Therefore, there is an advantage that one of the causes of deterioration of semiconductor characteristics can be easily removed.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view showing a schematic configuration of a centrifugal dryer according to an embodiment of the present invention, and FIG. 2 is a sectional view of a main part showing a specific embodiment of a closing means. DESCRIPTION OF SYMBOLS 1... Outer cylinder, 2... Drying chamber, 3... Turning table, 4... Drive mechanism, 8... Opening of outer cylinder, 9...
Lid body, 13... Air intake port, 14... Closure plate, 1
5... Spring.

Claims (1)

[Scope of Claim for Utility Model Registration] In a device that centrifugally dries cleaned wafers by holding them on a rotary table, an air intake provided in the outer cylinder of the drying chamber is provided with negative pressure inside the outer cylinder while the rotary table is rotating. A closing means is provided which operates to keep the air intake port open against the elastic force of the elastic body and to close the air intake port by the elastic force of the elastic body while the rotary table is stopped. Centrifugal dryer for semiconductor devices.