JPH0279430A - Method of drying wafer - Google Patents

Abstract

PURPOSE:To prevent air drying of waterdrops so as to prevent generation of water marks and to prevent a wafer from being charged with static electricity by drying the wafer in the specific atmosphere. CONSTITUTION:A wafer 11 is supported by the supporting part of a rotor 2, and the air mingled with steam is introduced into a casing 10 from the side of a suction pipe 15, and when the relative humidity inside the casing 10 has become over 80%, a rotary driving shaft 13 is driven to rotate a rotor 12. By making the atmosphere inside the casing 10 above 80% of relative humidity this way, the waterdrops at the surface of the wafer 11 become hard to vaporize, and only by severing them with centrifugal force the water drops are blown off, and the impurity which were dissolving in the water ceases to remain in the wafer. For this reason, it can prevent generation of water marks which are formed by impurity in the moisture gathering and adhering to the surface of the wafer.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for drying a wafer, and more specifically to a method for removing and drying water droplets attached to the surface of a semiconductor silicon wafer, a glass photomask, etc. This is related.

[Summary of the Invention] In a wafer drying method, the present invention prevents natural drying of water droplets by drying the wafer in an atmosphere with a relative humidity of 80% or more when drying the wafer using a spinner. This prevents the formation of water marks caused by residual dissolved matter on the wafer, and also prevents the wafer from being electrostatically charged.

[Prior Art] Conventionally, this type of wafer drying method is disclosed in, for example, Japanese Utility Model Publication No. 62-21002 and Japanese Utility Model Publication No. 62-2IQ03.

Both of these methods use a spinner drying method in which the wafer is rotated and water droplets are shaken off by centrifugal force.For example, as shown in FIG. is rotated at high speed to place water droplets on the air flowing from the intake port 4 side to the exhaust port 5 side, thereby expelling the water out of the casing l.

Another method is to expose the wafer to high-purity isopropyl alcohol (IPA) vapor, allow the distilled isopropyl alcohol to condense on the wafer, and wait for the water on the wafer surface to be replaced by isopropyl alcohol. IPA drying is known in which the wafer is then dried by evaporating isopropyl alcohol.

[Problems to be solved by the invention] However, in such conventional drying methods,
There are the following problems.

In the spinner drying method, the wafer is often placed on a water-repellent Teflon carrier. In this case, static electricity is generated on the wafer due to friction with the air, and since the Teflon carrier is an insulator, the wafer is placed on a water-repellent Teflon carrier. There was a problem in that static electricity generated by friction was charged. Another problem is that water evaporates before the water droplets are shaken off from the wafer surface due to rotation, and dissolved matter remains on the wafer surface, resulting in so-called watermarks. Measures to prevent watermarks include two-step rotation, first at low speed and then high-speed rotation, and by installing fixed blades inside the casing to prevent water droplets from returning to the wafer. Measures have been taken to improve airflow to prevent this from happening, but there are problems that cannot be fundamentally resolved.

On the other hand, the IPA drying method has the problem that impurities in the condensed IPA remain after evaporation, and there are also problems such as the inability to completely replace water that has entered the depths of steps such as trenches. .

The present invention has been made in view of these problems, and aims to provide a method for drying wafers that does not cause watermarks and is less likely to accumulate static electricity.

[Means for Solving the Problems] Therefore, the present invention provides the following features: When drying a wafer with a spinner, drying is performed in an atmosphere with a relative humidity of 80% or more.
This is the solution.

[Function] By drying the wafer with a spinner in an atmosphere with a relative humidity of 80% or more, there is an effect of shaking off water droplets with almost no water evaporation.

[Example] Hereinafter, details of the wafer drying method according to the present invention will be described based on an example shown in the drawings.

FIG. 1 is a sectional view of a drying device to which the present invention is applied.

In the figure, 10 is a substantially cylindrical casing, and an intake port 10a is provided at the center of the upper end surface, and an exhaust port 10b is provided at the periphery of the lower end surface. Inside the casing O, a cylindrical rotor 12 that accommodates and supports a plurality of wafers If is rotatably provided by a rotary drive shaft 13.

Further, a large number of holes 12a are formed in the side wall of the rotor 12 so that water droplets shaken off from the wafer 11 when the rotor 12 rotates can be discharged to the outside of the rotor 12. A plurality of fixed blades 14 are integrally disposed within the casing 1O at positions that revolve around the rotor I2.

An intake pipe I5 is electrically connected to the exhaust port 10a, so that clean air is introduced from the upstream side. In addition, the middle part of the intake pipe 15 has a reduced diameter part 15.
a, and a water supply device 1 is installed in this reduced diameter portion 15a.
A nozzle 16a for supplying pure water from 6 is arranged. In this way, the reduced diameter portion 15a and the water supply device 16 are connected to the spray device 1.
A throttle valve 18 is provided on the upstream side of the reduced diameter portion 15a, and a mist separator 19 using a HEPA filter or the like is provided on the downstream side.

Further, a heater 20 is provided upstream of the throttle valve 18, and supplies preheated air to the spray device 17 to vaporize the mist. Note that the mist that cannot be completely vaporized is captured by the mist separator 19.

A flow rate sensor 21, a temperature sensor 22, and a humidity sensor 23 are provided in the intake pipe 15 between the mist separator 19 and the intake port 101.

Furthermore, a temperature sensor 24 and a humidity sensor 25 are disposed within the casing IO in a space outside the fixed blade 14. Furthermore, a low temperature heater 26 is provided on the outside of the casing lO.
is installed.

In such a configuration, first, the wafer 11 is placed on the rotor 1.
2 support part (not shown), and introduce air mixed with water vapor into the casing 10 from the intake pipe 15 side, and when the relative humidity in the casing 10 reaches 80% or more, the rotary drive shaft 13 is driven. to rotate the rotor 12.

In this way, the atmosphere inside the casing 10 is adjusted to a relative humidity of 80
% or more, water droplets on the surface of sea urchin/%11 become difficult to evaporate, and the water droplets are blown off only by shaking off by centrifugal force, so that impurities dissolved in water do not remain on the wafer. Note that the evaporation of water is reliably suppressed when the relative humidity is 80% or more, especially when the humidity is close to 100%.

Such relative humidity is measured by the flow rate sensor 21. Temperature sensor 2
2,24. Based on the detected values of the humidity sensors 23 and 25, the heaters 20. It can be adjusted by controlling the throttle valve 18, water supply device, air introduction amount, etc.

Although the embodiments have been described above, various other design changes are possible.

For example, in the embodiment described above, the mist is generated by the spray device 17, but it goes without saying that a mist generator using ultrasonic waves or the like may also be used. Alternatively, water vapor may be supplied into the intake pipe 15 using another means.

[Effects of the Invention] As is clear from the above explanation, in the wafer drying method according to the present invention, water on the wafer surface does not evaporate by drying with a spinner in an atmosphere with a high relative humidity of 80% or more. Since water is removed only by shaking off by rotation, it is effective to prevent impurities in the water from agglomerating and adhering to the wafer surface, resulting in water marks.

Therefore, it has the effect of improving the performance of semiconductor devices and the like in which the wafer is used.

In addition, by drying in such high humidity,
This has the effect of preventing static electricity from forming due to friction with the air (relatively dry) as in the conventional case.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a drying apparatus to which a wafer drying method according to the present invention is applied, and FIG. 2 is a sectional view showing a conventional example. DESCRIPTION OF SYMBOLS 11... Wafer, 12... Rotor, 15... Intake pipe, 17... Spraying device, 19... Mist separator. Chizuami Ki Zeri Figure 2

Claims (1)

[Claims] (1) When drying the wafer with a spinner, the relative humidity is 8
A wafer drying method characterized by drying in an atmosphere of 0% or more.