JP3506851B2 - Steam drying apparatus and method for drying semiconductor wafer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor drying apparatus for drying an object to be dried, and more particularly to a vapor drying apparatus for semiconductor elements used in cleaning and wet etching processes and a method for drying a semiconductor wafer.

[0002]

2. Description of the Related Art Conventionally, as a technique in such a field,
For example, Japanese Patent Publication No. 6-2263 and Japanese Patent Publication No. 5-867.
No. 6, Japanese Patent Publication No. 3-44834, and Japanese Patent Publication No. 3-4
4835, Japanese Patent Publication No. 6-82647, Japanese Patent Publication No. 62-33314, Japanese Patent Publication No. 5-66726, "Optimum Precision Cleaning Technology" p191 to p201, 6.
3 There was a steam dryer by IPA, published by Techno System Co., Ltd., on February 12, 1990.

Generally, a conventional isopropyl alcohol (hereinafter referred to as IPA) vapor cleaning apparatus is disclosed in the above-mentioned document “Optimum precision cleaning technology, p191 to p201, 6.3.
Steam dryer by A ”.

FIG. 11 is a block diagram of such a conventional steam dryer.

As shown in this figure, this wafer vapor drying apparatus includes a vapor tank 101, a bottom heater 102, a sidewall heater 103, a cooling pipe 104, and a condensate tray 10.
5, an IPA heating / cooling system, a transport system for a material to be dried (silicon wafer) 121, an IPA canister 106, I
PA supply pipe 107, filter 108, IPA supply system including IPA liquid 109, IPA waste liquid pipe 110, exhaust port 111
Clean unit including, fan 112, filter 1
13, a specific resistance meter 114 and the like.

The IPA liquid 109 in the steam tank 101 is heated by the bottom heater 102 and the side wall heater 103 to evaporate, but is cooled by the cooling pipe 104 above the steam tank 101, condensed, and returned to the IPA liquid 109 again. Be done. Therefore, in the steady state, the vapor zone is formed above the IPA liquid 109.

The material to be dried (silicon wafer) 121 which has been washed / washed with water is transferred to the steam tank 10 by a transfer robot.
It is transferred to the vicinity of just above the condensate receiving tray 105 in 1.
The vapor of the IPA liquid 109 immediately condenses on the surface of the material to be dried 121 and dissolves in the water adhering to the surface of the material to be dried 121, and the melted water of the condensate drops to the condensate receiving tray 105 by its own weight, and the IPA Moisture whose boiling point is lowered due to melting starts to evaporate.

After the material to be dried 121 is sufficiently heated to the temperature of the steam in the steam tank 101, the material to be dried 121 is cooled by the cooling pipe 1.
It is transferred above 04 by a transfer robot. IPA is adsorbed on the material to be dried 121 heated in the steam tank 101, and the IPA adsorbed by the heat of the material to be dried 121 from the material to be dried 121 transferred above the cooling pipe 104 starts to evaporate. . After the IPA has evaporated, the drying is complete.

[0009]

However, in the above-mentioned conventional apparatus, the IPA in the steam tank is heated to a boiling state by a heater and a vapor zone is formed above the IPA liquid. Impurities in IPA are reduced as much as possible for the purpose of reducing contamination of a silicon wafer (hereinafter abbreviated as a wafer) forming a semiconductor integrated circuit as much as possible.

When the liquid containing a small amount of impurities is heated to a boiling state as described above, there are no seeds of boiling such as the side wall of the container and dust in the liquid. The boiling does not occur when the temperature rises above, and the liquid becomes heated. The liquid in a heated state suddenly boils, and becomes a sudden boiling state in which the liquid scatters. There is a problem that a small amount of impurities that have become seeds during bumping adhere to the material to be dried at the same time as the liquid is scattered, and contaminate the material to be dried.

Further, the condensate pan which is located above the liquid surface of the IPA is placed in a steam tank with feet under the pan. In the bumping state, friction occurs at the contact portion between the bottom of the condensate tray and the steam tank, and dust is generated. There is also a problem that this dust becomes a seed at the time of boiling and is diffused to the upper part of the IPA liquid tank at the same time as boiling and contaminates the material to be dried.

The present invention eliminates the above problems and provides a vapor drying apparatus for a semiconductor element and a method for drying a semiconductor wafer, which can prevent contamination of a semiconductor element which is an object to be dried due to bumping of a liquid that generates vapor. The purpose is to provide.

[0013]

In order to achieve the above-mentioned object, the present invention provides: (1) In a steam drying apparatus for drying an object to be dried, a needle-shaped convex object having an upper end on a bottom surface of the steam tank. Is formed and is provided in a liquid for generating steam so as to immerse the convex object.

As described above, by providing the convex projection, a portion which becomes a seed of boiling is formed, so that bumping can be prevented without being brought into a heated state.

Further, by providing the convex projection,
The contact area between the IPA liquid and the steam tank can be made wider than before, and the heat of the heater can be efficiently transferred to the IPA liquid.

( 2 ) In a steam drying apparatus for drying an object to be dried, liquid droplets falling from the object to be dried generated by condensation of vapor of the object to be dried are discharged to the outside of the steam tank in the steam tank. A support leg for supporting the condensate saucer provided for the purpose of preventing the liquid from contacting the steam tank and the steam tank and the saucer. A friction preventing member made of a material having sufficient chemical and thermal resistance and little dust generation is inserted between the supporting leg of the tray and the steam tank.

Therefore, direct friction between the steam tank and the foot of the condensate pan does not occur, so that dust generation is suppressed and the IPA
The amount of dust in the liquid does not increase.

Moreover, since only a plate or a cap is installed between the steam tank and the foot of the condensate tray, it is possible to form the existing apparatus without changing the shape of the apparatus and it is easy to implement. is there.

( 3 ) A semiconductor wafer is dried by using the vapor drying apparatus according to any one of (1) to ( 2 ) above.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of a steam drying apparatus showing a first embodiment of the present invention, and FIG. 2 is a sectional view showing a contact surface between an IPA liquid and a steam tank of the steam drying apparatus. The drying here means the sample surface of the solvent vapor [here, the main object of drying is a semiconductor element (wafer), but it also includes a cassette which is a container of the semiconductor element, and in that sense, the object to be dried is It refers to. ] It is a substitution dehydration drying method in which moisture is removed by condensation to

In these figures, the steam tank 1 is provided with IPA supply lines 9 and I for supplying the IPA liquid 2 into the steam tank.
IPA waste liquid line 13 used for waste liquid of PA, condensate tray 5 for discharging the condensate to the outside of the steam tank 1, bottom heating heater (hereinafter simply referred to as heater) 3 for raising the temperature of IPA liquid 2, vaporization The cooling pipe 4 is provided for keeping the generated IPA vapor in the vapor tank.

The material of the steam tank 1 is, for example,
Quartz or stainless steel subjected to electrolytic composite polishing is used.
Similarly, as the material of the condensate pan 5, quartz, electrolytically composite-polished stainless steel, or the like is used.

The IPA supply line 9 comprises a filter 7 for removing dust in the IPA and a supply valve 12 for controlling the IPA supply.
The IPA canister can 6 containing PA is connected, and I
A pressure line 8 for pressure-feeding IPA is connected to the PA canister can 6. The pressurizing line 8 is provided with a pressurizing gas valve 11 for controlling the pressurizing gas. A condensate waste liquid line 10 for discharging the condensed IPA to the outside of the steam tank 1 is connected to the condensate tray 5.

The IPA waste liquid line 13 is provided with a waste liquid valve 14 for controlling the waste liquid of the IPA, and the condensate waste liquid line 10 is closer to the waste liquid line than the waste liquid valve 14.
Connected with.

In the first embodiment, as shown in FIG. 1, a convex protrusion 15 is provided on the bottom of the steam tank 1 on the surface in contact with the IPA liquid 2.
To provide. FIG. 2 is an enlarged view of the contact surface. The material of the convex protrusion 15 is the same as that of the steam tank 1, and the steam tank 1 is bonded by a method such as welding or fusion without using any other material. Or the one formed by carving out the steam tank 1 to form the convex protrusion 15, and the upper end of the convex protrusion 15 is formed in a needle shape, and the convex protrusion is also formed. The upper end of 15 is formed below the liquid surface.

The operation of this steam dryer will be described below.

First, the pressurized gas valve 11 of the pressurized line 8
Opens, and the IPA canister can 6 is pressurized. afterwards,
The supply valve 12 is opened, and IPA is supplied to the steam tank 1 through the filter 7 by the IPA supply line 9. Steam tank 1
When the amount of IPA supplied to the valve reaches a predetermined amount, the supply valve 1
2 is closed and the supply of IPA is stopped. After being stopped, the heater 3 starts to raise the temperature of the IPA liquid 2 supplied to the steam tank 1. The IPA liquid 2 heated to near the boiling point starts boiling with the needle-shaped upper end portion of the convex protrusion 15 as a seed for boiling.

As described above, according to the first embodiment, since the protrusions 15 having a convex shape are provided, a portion which becomes a seed of boiling is formed. it can. Moreover, by providing the convex protrusions 15, the contact area between the IPA liquid 2 and the steam tank 1 can be made wider than in the conventional case, and the heat of the heater 3 can be efficiently supplied to the IPA.
Liquid 2 can be transmitted.

Next, a second embodiment of the present invention will be described.

FIG. 3 is a schematic configuration diagram of a steam drying device showing a second embodiment of the present invention, FIG. 4 is a configuration diagram of a bubbler of the steam drying device, and FIG. 4 (a) is a rear view thereof. (B) is the side view. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this second embodiment, as shown in FIGS. 3 and 4, in order to introduce a gas into the IPA liquid 2 inside the steam tank 1, a tubular bubbler 16 having fine holes 17 is steamed. It is provided in the tank 1. The gas introduced into the IPA liquid 2 is an inert gas with few impurities, such as N ₂
It is a gas that can reduce impurities such as gas.
A gas valve 18 is attached to the bubbler 16 so that the gas introduced can be controlled. The bubbler 16 is composed of one or more in order to uniformly introduce the gas into the IPA liquid 2, and the fine holes 17 formed in the bubbler 16 are
The amount of gas that does not heat the IPA liquid 2 to the bubbler 1
It is processed so that it can be uniformly introduced from the tip of 6 to the portion where the bubbler 16 is introduced into the IPA liquid 2.

The operation of this steam dryer will be described below.

First, as in the first embodiment, the pressure line 8
The pressurized gas valve 11 is opened, and the IPA canister 6 is pressurized. After that, the supply valve 12 is opened, and the IPA supply line 9 passes through the filter 7 to enter the IPA into the steam tank 1.
To supply. When the IPA supplied to the steam tank 1 reaches a predetermined amount, the supply valve 12 is closed and the supply of IPA is stopped. After being stopped, the heater 3 starts to raise the temperature of the IPA liquid 2 supplied to the steam tank 1.

In this second embodiment, after the IPA liquid 2 is heated to near the boiling point, the gas valve 18 is opened and the IPA liquid 2 is opened.
N ₂ gas is introduced through the fine holes 17 formed in the bubbler 16 inside. The introduced N ₂ gas diffuses into the IPA liquid 2, and the diffused N ₂ gas becomes a seed to start boiling the IPA liquid 2.

As described above, according to the second embodiment, since the N ₂ gas can be uniformly introduced into the IPA liquid 2,
During boiling, N ₂ gas becomes a seed and does not become a heated state, so bumping can be prevented.

Further, N ₂ can push up the IPA vapor generated at the interface of the IPA liquid 2 upward, and a large amount of vapor can be supplied to the material to be dried.

Next, a third embodiment of the present invention will be described.

FIG. 5 is a schematic configuration diagram of a steam drying apparatus showing a third embodiment of the present invention, and FIG. 6 is a perspective view of a baffle plate portion of the steam drying apparatus. The same components as those in the first embodiment are designated by the same reference numerals and their description will be omitted.

The silicon wafer 20 which is the object to be dried and the carrier 21 for accommodating the silicon wafer 20 and facilitating the transportation thereof are located at a position immediately above the condensate receiving tray 5 in the steam tank 1 after the washing / water washing process is completed. Be transferred.

In this third embodiment, the IPA inside the steam tank 1 is
Above the liquid 2 and below the silicon wafer 20, plate-shaped inclined baffle plates 19 are arranged in parallel so as to have a line-symmetrical inclination with the center of the steam tank 1 as the center. Further, the baffle plate 19 is installed as shown in FIG.

The inclination and size of the baffle plate 19 depend on the IPA.
When the liquid 2 is viewed from above, the liquid 2 is formed so as to be completely hidden vertically above the central portion of the steam tank 1 except for the axisymmetric center portion. For example, the thickness of the steam tank is 5 mm, the width is 40 mm, and the length is the same as that of the steam tank 1. The baffle plate is tilted by 45 degrees, and the size of the parallel plane of the IPA liquid 2 is 500 mm square. A clearance is provided, and the interval of the lower side of the baffle plate 19 is set to 17.5 mm, and 28 sheets are installed.

The operation of this steam dryer will be described below.

The IPA liquid 2 is heated by the heater 3 as in the first and second embodiments. Since the IPA liquid 2 is a liquid with few seeds, it is heated and is in a heated state. The IPA liquid 2 in the heated state causes bumping. The bumped liquid tends to be scattered above the steam tank 1. The liquid scattered on the IPA liquid 2 collides with the baffle plate 19 above it.

As described above, according to the third embodiment, the liquid scattered by the bumping is obstructed by the baffle plate 19 and is not scattered above the baffle plate 19, so that even if the bumping occurs, the silicon wafer 20 is not exposed. Since the scattered liquid generated by bumping does not adhere, the silicon wafer 20 can be dried in a clean state. In addition, since the baffle plate 19 has an inclination toward the center of the steam tank 1, a steam flow is formed in the direction of the silicon wafer 20 and faster drying is possible.

Next, a fourth embodiment of the present invention will be described.

FIG. 7 is a schematic configuration diagram of a steam drying apparatus showing a fourth embodiment of the present invention, and FIG. 8 is a plan view of a lower cooling plate portion of the steam drying apparatus showing the fourth embodiment of the present invention. The first
The same components as those in the embodiment and the third embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In the fourth embodiment, the IP inside the steam tank 1 is
Above the second surface of the liquid A and below the silicon wafer 20,
A lower cooling pipe 22 was provided parallel to the second surface of the IPA liquid, and was reciprocated in a meandering manner from the inlet of the steam tank 1 to the outlet thereof. When the lower cooling pipe 22 reciprocates, the forward path and the return path are installed parallel to each other, the material of the lower cooling tube 22 is the same as that of the steam tank 1, and the inner diameter of the tube is a coolant (for example, water). 0.0
A flow control valve 23 having a diameter capable of flowing 05 to 5 L / min and capable of controlling the flow rate of the cooling liquid is attached to the outside of the steam tank 1 at the inlet side, that is, the supply side of the lower cooling pipe 22.

The operation of this steam dryer will be described below.

As with the third embodiment, the IPA liquid 2 is heated by the heater 3.

Since the IPA liquid 2 is a liquid containing few seeds, the IPA liquid 2 is heated to be in a heated state. The IPA liquid 2 in the heated state causes bumping. The bumped liquid tends to be scattered above the steam tank 1. In the fourth embodiment, the steam generated in the steam tank 1 is the lower cooling pipe 22 installed above the IPA liquid 2 surface.
Part of the liquid is cooled by the cooling liquid flowing into the liquid and condenses into droplets. The IPA that has become droplets drops onto the IPA liquid 2.

The amount of vapor condensed is determined by the lower cooling pipe 2.
2 can be controlled by the flow rate of the cooling liquid flowing inside the wafer 2. In the conventional example, after the wafer 20 is sufficiently heated to the temperature of the steam in the steam tank 1, the wafer 20 is transferred above the cooling pipe by the transfer robot. However, in the fourth embodiment, the supply of the vapor to the wafer 20 can be stopped by increasing the flow rate of the cooling liquid in the lower cooling pipe 22.

As described above, in the fourth embodiment, the IPA liquid 2
The vapor evaporated from the above is partially cooled and drops onto the IPA liquid 2. On the other hand, bumping has occurred in the IPA liquid 2 in the heated state, and the liquid is scattered upward. However, in the fourth embodiment, the falling liquid drops interfere with the upwardly scattered liquid drops, and the falling liquid drop is falling while taking in the scattered liquid drops. The wafer 20 cannot be reached. Therefore, the wafer 20 can be dried cleanly.

Further, since the flow rate of the cooling liquid flowing through the cooling pipe 22 is controlled by the flow rate control valve 23, the vapor amount to the wafer 20 can be controlled, so that the IP can be controlled without moving the wafer 20.
It is possible to perform control including stopping supply of the steam of A. Therefore, it is safer than the conventional method in which the IPA is evaporated outside the steam tank 1.

Next, a fifth embodiment of the present invention will be described.

FIG. 9 is a schematic block diagram of a steam drying apparatus showing a fifth embodiment of the present invention, and FIG. 10 is a schematic block diagram showing a modified example of the steam drying apparatus. The same components as those in the first embodiment are designated by the same reference numerals and their description will be omitted.

As shown in FIG. 9, the condensate tray 5 is an IP.
It is provided so as to be located above the second surface of the liquid A. Although the supporting legs 25 are provided on the condensate receiving tray 5, the bending elastic modulus is low at the contact portion with the steam tank 1, and the chemical resistance (for example, chemical change, corrosiveness, etc.) and the thermal resistance (for example, for the IPA liquid) are maintained. , Thermal deformation, thermal damage), and a plate-like friction prevention so that the support legs 25 of the condensate receiving tray 5 and the steam tank 1 do not come into direct contact with each other by PFA or PTFE, which has a small amount of dust generation. A plate (friction prevention member) 24 is inserted.

Further, as shown in FIG. 10, a friction preventing cap (friction preventing member) 26 may be provided so as to cover the base of the supporting leg 25 of the condensate receiving tray 5.

The operation of this steam dryer will be described below.

The IPA liquid 2 is heated by the heater 3 as in the first to fourth embodiments. Since the IPA liquid 2 is a liquid with few seeds, the temperature is raised and the IPA liquid 2 is heated. The IPA liquid 2 in the heated state causes bumping. The bumping causes friction between the support foot 25 of the condensation tray and the anti-friction plate 24, or friction between the anti-friction cap 26 installed on the support foot 25 of the condensate tray and the steam tank 1.

As described above, according to the fifth embodiment, since the direct friction between the steam tank 1 and the foot 25 of the condensate receiving tray 5 does not occur, dust generation is suppressed and the dust in the IPA liquid does not increase. .

Moreover, since only a plate or a cap is installed between the steam tank 1 and the foot 25 of the condensate tray 5, it is possible to form the existing apparatus without changing the shape of the apparatus, and it is easy. It is feasible.

In each of the above embodiments, IPA was used as an example of the solvent used in the chemical drying method, but a wide range of liquids that can be vaporized may be used. Specifically, a material having a small surface tension of about 20 dyn / cm is used. For example, alcohols such as IPA and chlorine-based solvents such as Freon 113 can be used.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention.

[0065]

As described in detail above, according to the present invention, the following effects can be obtained.

(1) According to the first aspect of the present invention, since the convex protrusion is provided, a portion which becomes a seed for boiling is formed. it can.

Further, by providing the convex projection,
The contact area between the IPA liquid and the steam tank can be made wider than before, and the heat of the heater can be efficiently transferred to the IPA liquid.

( 2 ) According to the second aspect of the present invention, since the friction between the steam tank and the foot of the condensate pan does not occur directly,
Dust generation is suppressed and dust in the IPA liquid does not increase.

Moreover, since only the plate or the cap is installed between the steam tank and the foot of the condensate pan, the existing device can be formed without changing its shape, and it can be easily implemented. is there.

( 3 ) According to the invention described in claim 3 , the semiconductor wafer can be cleanly dried.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a steam drying apparatus showing a first embodiment of the present invention.

FIG. 2 is an IP of a steam dryer showing a first embodiment of the present invention.
It is sectional drawing which shows the contact surface of A liquid and a steam tank.

FIG. 3 is a schematic configuration diagram of a steam drying apparatus showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a bubbler of a steam drying device showing a second embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a steam drying apparatus showing a third embodiment of the present invention.

FIG. 6 is a perspective view of a baffle plate portion of a steam drying apparatus showing a third embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a steam drying apparatus showing a fourth embodiment of the present invention.

FIG. 8 is a plan view of a lower cooling plate portion of a steam drying device showing a fourth embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of a steam drying apparatus showing a fifth embodiment of the present invention.

FIG. 10 is a schematic configuration diagram showing a modified example of the steam drying apparatus according to the fifth embodiment of the present invention.

FIG. 11 is a schematic configuration diagram of a conventional steam dryer.

[Explanation of symbols]

1 steam tank 2 IPA liquid 3 heating heater 4 cooling tubes 5 Condensate pan 6 IPA canister cans 7 filters 8 pressure line 9 IPA supply line 10 Condensate waste liquid line 11 Pressurized gas valve 12 Supply valve 13 IPA waste liquid line 14 Waste liquid valve 15 Convex protrusion 16 Bubbler 17 holes 18 gas valve 19 baffle 20 Silicon wafer 21 career 22 Lower cooling pipe 23 Flow control valve 24 Plate-shaped anti-friction plate (anti-friction member) 25 Supporting feet 26 Anti-friction cap (anti-friction member)

Claims (3)

(57) [Claims] 1. A steam drying apparatus for drying a material to be dried, wherein a convex object having a needle-shaped upper end is formed on a bottom surface of the steam tank, and the convex object is immersed in a liquid for generating steam so as to immerse the convex object. A steam drying device characterized by being provided. 2. A steam drying device for drying an article to be dried, for discharging droplets falling from the article to be dried, which are generated by condensation of vapor of the article to be dried, in the steam tank to the outside of the steam vessel. A supporting leg for supporting the condensate saucer provided in, and a liquid that has a lower bending elasticity than the material that constitutes the steam tank and the saucer so that it does not come into contact with the steam tank and that generates steam. A steam drying apparatus, characterized in that a friction preventing member made of a material having sufficient chemical and thermal resistance and little dust generation is inserted between a supporting leg of the tray and the steam tank. 3. Using the vapor drying apparatus according to any one of claims 1-2, the drying method of a semiconductor wafer, characterized in that drying the semiconductor wafer.