JPH0143862Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a wafer drying apparatus, and more particularly to an improvement of a centrifugal dehydration type wafer drying apparatus used when drying semiconductor wafers housed in a wafer carrier.

When manufacturing semiconductor devices, in a batch-type wafer process process in which multiple semiconductor wafers are processed as one lot, the semiconductor wafers are cleaned and dried while being stored in a wafer carrier for each lot between each process. .

At this time, even if the semiconductor wafer is sufficiently cleaned by thorough cleaning, the drying method may contaminate the wafer surface, attach dust to the wafer surface, or scratch the wafer surface. If there are such problems, the performance and manufacturing yield of the semiconductor device will deteriorate.

A centrifugal dehydration type wafer drying apparatus is usually used as the batch type wafer drying means, and there is a strong demand for the development of a centrifugal dehydration type wafer drying apparatus that eliminates the above-mentioned problems.

[Conventional technology]

The conventional centrifugal dehydration type wafer drying equipment is
As shown in the schematic side sectional view a and the schematic top view b shown in the figure, the semiconductor wafer 1 is placed on the wafer carrier 2a,
2b, 2c, 3d, etc., a rotary container 3 placed in a state of being stored, an external container 4 containing the rotary container 3, a motor 5 for rotating the rotary container 3,
It is mainly composed of a cover plate (not shown).

The rotary container 3 has a gutter-like shape, and is provided with a number of drainage holes 6 on its side wall, and is fixedly engaged with the shaft 7 of the motor 5 made of a rigid body at the geometric center position of the bottom surface. .

Further, the outer container 4 is provided with a drain port 8, and the shaft 7 of the motor 5 is inserted into the outer container 4 via a bearing 9.

In the figure, numeral 10 indicates a wafer carrier fixing means, and numeral 11 indicates a leg body.

In the conventional apparatus, semiconductor wafers are dried only by a so-called centrifugal dehydration means that shakes off water droplets by centrifugal force generated when the rotating container 3 is rotated at high speed.

[Problem that the invention attempts to solve]

In such a conventional wafer drying apparatus, since the rotary container 3 and the motor 5 are engaged with each other by the rigid shaft 7 as described above, each wafer carrier 2
There is no particular problem if the number of semiconductor wafers 1 stored in carriers a, 2b, 2c, and 2d is approximately equal, but if the number of wafers in each carrier is, for example, 20, 5
When there are extreme fluctuations such as 10 pieces, 10 pieces, 15 pieces,
Since the center of gravity of the rotating container 3 is shifted and no longer coincides with the center of rotation, vibration occurs in the rotating container 3, and this vibration is transmitted to the wafer carriers 2a, 2b, 2c, 2d.
The carrier and the semiconductor wafer 1 housed in it collide and the impact causes damage to the semiconductor wafer.The carrier, which is made of Teflon or the like, is scraped and generated, and the semiconductor wafer is damaged. Problems have arisen, such as contamination of the surface of the semiconductor wafer by debris generated when the wafer is chipped.

In addition, in order to withstand the above vibrations, the bearing must be made stronger than necessary, the inner container must be thickened to increase its strength, and the motor power must also be increased, which is not desirable in terms of equipment design. There was a problem.

Furthermore, in the conventional apparatus described above, since no ventilation means is provided inside the container, there is a problem that the drying of the semiconductor wafer is incomplete and contaminants are likely to adhere to the wafer surface.

[Means for solving problems]

The solution to the above problem is to provide a first container that is engaged with a rotating shaft via a flexible coupling means and has a first hole on its side surface, and a a blowing means for blowing out gas toward the inner surface of the first container; a second container enclosing the first container and having a second hole on the side surface; and a second container disposed on the outer surface of the second container. This is achieved by a wafer drying apparatus according to the invention having exhaust means provided.

[Effect]

That is, in the wafer drying apparatus of the present invention, the rotating shaft that engages the motor and the rotating container is made flexible to reduce vibrations of the rotating container.

This is based on the following principle, which will be explained using a schematic side sectional view a and a forced vibration state diagram b shown in FIG.

In the figure, 21 is the motor, 22 is the shaft of the motor, 23 is the rotation axis, 24 is the object to be rotated, G is the center of gravity of the object to be rotated, O is the geometric center of the object to be rotated, and S is the object to be rotated. , K is the spring constant of the rotating shaft, ω _o is the resonance frequency of this system, m is the weight of the object to be rotated, r _p is the distance between S and O, e is the distance between O and G, and then , The centrifugal force when a certain rotational speed ω is given is m(r _p +e)ω ² =Kr _p .

Furthermore, there is a relationship of ω _o ² =K/m, and by setting ω/ω _o =β, the following relational expression can be obtained.

r _p /e=β ² /(1−β ² ) The relationship between r _p /e and β is illustrated in FIG. 4b for a system having a predetermined damping effect.

From this figure, by increasing ω/ω _o, that is, β,
It can be seen that r _p /e becomes smaller and approaches 1. That is, since the object to be rotated tries to rotate around its geometric center, the vibration of the shaft becomes smaller.

In the present invention, by making the rotating shaft flexible, it is possible to lower ω _o (resonant rotational speed) and easily achieve the above effect. This will reduce the vibration.

In addition, an air supply pipe having a large number of gas blowing holes for spouting dry gas toward the inner surface of the rotary container is arranged near the central axis of the rotary container along the central axis, and a large number of gas blowing holes are provided on the side surface of the outer container. Provided with ventilation holes,
Furthermore, by forming an exhaust duct on the outer surface of the outer container, a flow of drying gas is created between the wafers housed in layers in the wafer carrier from the air supply pipe toward the inner surface of the rotating container. Wafer drying is accelerated.

In this way, problems such as wafer damage, contamination, and incomplete drying due to the drying process are reduced, and the strength of the bearings and the entire apparatus, as well as the output of the motor, can be reduced.

〔Example〕

The present invention will be specifically explained below with reference to an embodiment shown in the drawings.

Fig. 1 is a schematic side sectional view of an embodiment of the present invention, Fig. 2 is a perspective view schematically showing the structure of the engagement means using a gimbal spring, and Fig. 3 shows the flow of drying gas during the drying process. It is a schematic side sectional view.

Identical objects are indicated by the same reference numerals throughout the figures.

As shown in FIG. 1, the wafer drying apparatus of the present invention has a gutter-like shape, and has a plurality of first holes 6 formed on the sides that function for drainage and ventilation, and the semiconductor wafer 1 is placed in a wafer carrier 2a, 2c and 2b, 2d (not shown), etc., with a rotary container (first container) 3 having a structure similar to the conventional one, and containing the rotary container 3 and having a large number of vents and vents on the sides. an outer container (second container) 14 having a second hole 13 that also functions as a drainage hole and a drain port 8 at the bottom; an exhaust duct 15 configured to include an exhaust duct 15, a rotating shaft fixed to the tip of the shaft 7 of the motor 5 inserted from the bottom of the outer container 14 via a bearing 9, and the geometric center of the rotating container 3; A flexible engagement means 17 using, for example, a gimbal spring, connects to the shaft 16, and a large number of gas ejection holes 18 that eject dry gas from the inside of the rotary container 3 toward the inner surface of the rotary container 3. and a cover plate 20 having an air supply pipe 19 fixed at approximately the center axis position of the rotary container 3.

In addition, in the figure, 11 indicates a leg body.

In this embodiment, as described above, the rotating shaft 16 of the rotating container is made flexible by engaging with the shaft 7 of the motor 5 by means of an engagement means using a gimbal spring. vibration is reduced.

FIG. 2 is a perspective view schematically showing the structure of the engagement means using cymbal springs, and 7 shows the shaft of the motor;
31 is a first support arm fixed to the shaft 7 of the motor; 16 is a rotating shaft fixed to the rotating container; 32
is a second fixed to the lower end of the rotating shaft 16 of the rotating container.
, 33 is a cross-shaped leaf spring, and 34 is a fixing screw.

To further increase flexibility, the gimbal springs are stacked in multiple tiers.

However, the flexible engagement means is not limited to the gimbal spring structure described above.

Further, in this embodiment, as described above, an air supply pipe 19 is arranged near the central axis of the rotating container 3 and blows out dry gas (dry nitrogen, dry air) toward the inner surface of the rotating container 3. and the first hole 6 of the rotary container 3 and the outer container 1 from the side of the rotary container 3.
Since the air is taken in by the exhaust duct 15 through the second hole 13 of 4, a strong flow of the ejected gas flows to the wafer carriers 2a, 2c and 2 (not shown).
Since it is formed between the wafers 1 housed in layers in containers b and 2d, centrifugal dehydration by rotation of the container is promoted, and at the same time, drying after dehydration is sufficiently performed.

FIG. 3 is a schematic side sectional view showing the flow of drying gas during the drying process, in which 1 is a semiconductor wafer, 3 is a rotating container, 6 is a first hole, and 13 is a second hole.
14 is an external container, 15 is an exhaust duct, 18
19 is a gas blowing hole, 19 is an air pipe, and F is a dry gas streamline.

[Effect of idea]

As explained above, in the wafer drying apparatus of the present invention, by making the rotating shaft of the rotating container flexible, the vibration of the wafers accommodated in the wafer carrier is reduced, and the wafers accommodated in the wafer carrier in a layered manner are Drying was promoted by forming a strong flow of drying gas between the semiconductor wafers from the center of the rotating container toward the periphery.

Therefore, according to the present invention, damage and contamination of semiconductor wafers are prevented and the performance and manufacturing yield of semiconductor devices are improved.

Also, by reducing vibration, it is possible to reduce the mechanical strength of bearings, rotating containers, etc.
In addition, since the output of the motor can be reduced, device design becomes easier.

[Brief explanation of the drawing]

Fig. 1 is a schematic side sectional view of an embodiment of the present invention, Fig. 2 is a perspective view schematically showing the structure of the engagement means using a gimbal spring, and Fig. 3 shows the flow of drying gas during the drying process. 4 is a schematic side sectional view a and a schematic top view b of a conventional wafer drying apparatus, and FIG. 5 is a schematic side sectional view a of a rotating system with a flexible shaft and a state diagram of forced vibration b , is. In the figure, 1 is a semiconductor wafer, 2a, 2
c, wafer carrier, 3 rotating container (first container), 5 motor, 6 first hole, 7 motor shaft, 9 bearing, 13 second hole, 14
is an external container (second container), 15 is an exhaust duct,
16 is a rotating shaft, 17 is a flexible engagement means,
18 is a gas outlet, 19 is an air pipe, 20 is a cover plate,
shows.

Claims (1)

[Scope of utility model registration request] a first container that is engaged with the rotating shaft via a flexible coupling means and has a first hole on the side surface; A blowing means for blowing out gas towards the front, a second container enclosing the first container and having a second hole on the side surface, and an exhaust means disposed on the outer surface of the second container. A wafer drying device comprising: