JPH05326475A - Wafer holder for cleaning and etching - Google Patents

Abstract

PURPOSE:To improve the uniformity of cleaning and etching operations by forming guides of a holder therefor to hold a large number of wafers in a standing position such that they are parallel with one another and slanted from the perpendicular in the same direction. CONSTITUTION:A wafer holder body consists of a pair of side panels 1 provided with a wafer supporting body 2 and a wafer support bar 6, each, and a pair of end panels 9. Each side panel 1 has two openings 5 and 8 adjacent to the respective wafer supporting body 2. The wafer supporting bodies 2 and wafer support bars 6 are provided with guides 4a and 4b to hold wafers 3. All the guides 4a and 4b are formed in a way that they are parallel with one another and slanted from the perpendicular by an angle of approx. 86.5 degrees in the same direction. Thus wafers 3, when set in the guides 4a and 4b, are slanted to the left by their weight, kept from contact with one another.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning / etching wafer holder used for cleaning or etching a semiconductor wafer in a semiconductor product manufacturing process.

[0002]

2. Description of the Related Art Semiconductor wafers are cleaned and etched in the manufacturing process of semiconductor products, and a resin wafer holder that can accommodate a large number of semiconductor wafers is used in such processing processes. To be done.
For example, in Japanese Unexamined Patent Publication No. 61-189647, a large number of elongated guides forming a pair are provided in parallel on the inner surface side of the holder main body to form a groove, and the lower part of the main body corresponds to the guide. There is disclosed a type in which a grooved support portion is provided and a semiconductor wafer is inserted into the groove of the guide and the support portion. Since the groove for holding the wafer is perpendicular to the longitudinal direction of the elongated guide and the wall surface of the holder, the held wafer is
Although it may be slightly inclined due to the clearance between the groove and the wafer, it is almost upright and perpendicular to the longitudinal direction of the elongated guide and the wall surface of the holder.

[0003]

In the steps of cleaning and etching, a semiconductor wafer is kept immersed in a wafer holder and immersed in a treatment solution, and a treatment is carried out for a certain period while rocking. The swinging has effects such as promptly removing bubbles generated during processing and facilitating liquid exchange in the vicinity of the wafer, thereby increasing the uniformity of processing. By the way, in the case of the wafer holder described in Japanese Patent Laid-Open No. 61-189647, the wafer to be cleaned is almost fixed in the initial stage of use because the shape and dimension thereof are small, but it is used many times. If so, the groove for holding the wafer is gradually shaved and it becomes difficult to fix the wafer, and even adjacent wafers may come into contact with each other. If they come in contact with each other, the surface of the wafer will be damaged, but even if they do not come in contact with each other, if the intervals between the wafers to be processed are different from one wafer to another, or if they are different from one another to another, the cleaning and etching conditions will be uneven. As a result, it becomes impossible to ensure the uniformity of the processing even by the rocking.

The present invention solves the above-mentioned problems by devising such that the distance between held wafers is always kept constant, and provides a wafer holder for cleaning / etching which can efficiently perform cleaning or etching. The purpose is to do.

[0005]

SUMMARY OF THE INVENTION The present invention provides a wafer cleaning or etching holder having a guide for holding a large number of wafers in an upright state, wherein the guides are parallel to each other and are the same with respect to the vertical. The gist of the present invention is a wafer holder for cleaning / etching, which is provided so as to be inclined in the direction.

[0006]

The specific construction and operation of the present invention will be described below with reference to the drawings. 1, 2 and 3 show the cleaning of the present invention.
It is an example of an etching wafer holder, and is an external view and two sectional views. 2 is a side sectional view, and FIG. 3 is a sectional view showing a section perpendicular to the plane of FIG. 2 and passing through the line SS ′. As shown in the figure, the main body of the wafer holder comprises a pair of end plates 9 and a pair of side plates 1 which are different from each other. A wafer support 2 and a wafer support rod 6 are mounted on the side plate 1 and adjacent to them are two openings 5 and 8. The wafer support 2 and the wafer support rod 6 have guides 4 (a) and 4
(B) is provided and forms a guide for holding the wafer 3. As shown in FIG. 2, the plurality of guides 4 (a) and 4 (b) provided in parallel with each other are not perpendicular to the longitudinal direction D (arrow) of the wafer support rod 6 but are constant. It is inclined at an angle, and in this example, the angle is about 86.5 degrees (hereinafter, this angle is referred to as a “tilt angle”). The angle θ formed by the guide and the vertical direction is 90 degrees minus the tilt angle, and is about 3.5 in this example.
It is degree.

The wafer before cleaning or etching is in a state indicated by A in FIG. Guide 4
The wafers set in (a) and (4) are all tilted to the left due to gravity, so that the wafer intervals are naturally constant and do not contact each other. On the other hand, the tilt angle is 9
In the conventional 0 ° wafer holder, the wafer tilts leftward or rightward and is not constant. Therefore, the guides 4 (a) and 4 (b) are gradually scraped by many times of use, and the clearance with the wafer is gradually reduced. If they are large, they may contact each other. When cleaning or etching with a wafer holder of the type shown in FIG. 2, rocking is usually applied in the vertical direction. When the wafer holder shown in FIG. 2 is swung downward, the cleaning or etching solution tries to push the wafer upward, so that all the held wafers are in the B state. When the holder is swung upward, the cleaning or etching solution tries to push the wafer downward, so that all the held wafers are in the A state again. In the wafer holder for cleaning / etching of the present invention, the distance between the wafers to be processed is always held in a constant direction regardless of the position, so that the wafers may come into contact with each other and the surface may be damaged. The cleaning and etching conditions do not become uneven. On the other hand, in the conventional wafer holder with a tilt angle of 90 degrees, the wafers are tilted leftward or rightward due to the swinging and are not constant, so that the wafers come into contact with each other to cause flaws on the surface or cleaning. Or the etching situation becomes uneven.

In the cleaning / etching wafer holder of the present invention, when the tilt angle exceeds 89 degrees, the tilt angle is 90 degrees.
In practice, the wafer holder becomes substantially the same as the conventional wafer holder, and the distance between the wafers to be processed cannot be kept constant, which may cause the above-mentioned problems. In the cleaning / etching wafer holder of the present invention, when the tilt angle is less than 80 degrees, it becomes difficult to take in and out the wafer, and therefore the preferred tilt angle is from 80 degrees to 89 degrees.

The cleaning / etching wafer holder of the present invention is also useful when it is rocked by rotation, and FIG. 4 shows an example of such a holder. 4 and 5 show an example of the wafer holder of the present invention, which is an external view and a side sectional view. As shown in the figure, the wafer holder body comprises a pair of side plates 10 and four wafer holding rods 11. The side plate 10 has a wafer rotation support 12 and an opening 14. Wafer support rod 11
A groove for supporting the wafer 13 is formed therein. As shown in FIG. 5, the plurality of grooves provided in parallel with each other are not perpendicular to the longitudinal direction E (arrow) of the wafer support rod but are inclined at a constant angle. The angle is about 84.5 degrees.

When the holder shown in FIG. 4 is swung at a rotational speed of about several tens of minutes per minute, the wafers to be held are pressed in a certain direction by the centrifugal force. It is always kept constant regardless of In contrast,
In the conventional wafer holder with an inclination angle of 90 degrees, the wafers are tilted to the left or to the right due to rocking and are not constant. Therefore, the wafers come into contact with each other to cause surface flaws, and the cleaning and etching conditions. May become uneven.

[0011]

【Example】

(1) A silicon wafer having a thickness of 6000Å and a thermally oxidized SiO ₂ film was set on the wafer holder shown in FIGS. This holder is the wafer holder of the present invention, and the tilt angle is about 86.5 degrees. Next, the holder with the wafer set therein is dipped in a buffered hydrofluoric acid solution (50% hydrofluoric acid: 40% ammonium fluoride mixed at a volume ratio of 1:10) and rocked up and down. Etching was performed for 4 minutes and 40 seconds. For comparison, a similar test was performed on a wafer holder having an inclination angle of 90 degrees. After rinsing with ultrapure water and drying with a centrifugal dryer, the oxide film thickness distribution after etching was examined with an ellipsometer. When the wafer holder of the present invention was used, the variation in oxide film thickness after etching (standard deviation) on one wafer was 5% or less, and between wafers was 7% or less. In the case of the comparative example, the variation in oxide film thickness after etching on one wafer was about 15%, and between wafers was about 20%. As described above, in the wafer holder for cleaning / etching of the present invention, etching occurs uniformly and the difference between wafers is small.

(2) After cleaning the silicon wafer rough-polished in the lapping step, it was set on the wafer holder shown in FIG. The holder of FIG. 4 is the wafer holder of the present invention, and the tilt angle is about 85 degrees. Next, a fluorinated nitric acid solution (50% hydrofluoric acid: 70% nitric acid: 100% acetic acid 3: 5:
The holder on which the wafer was set was dipped in a mixed acid mixed at a volume ratio of 3) and etched for 70 seconds while rocking at a rotation speed of 40 rpm. For comparison, a similar test was performed on a wafer holder having an inclination angle of 90 degrees.
After rinsing with ultrapure water, it was taken out from the holder and dried, and the presence or absence of etching unevenness was examined. When the wafer holder of the present invention was used, etching unevenness did not occur at all, but in the comparative example, etching unevenness was scattered. Further, there is a difference in shape after etching, and when the wafer holder of the present invention is used, there is almost no difference between wafers. In the case of the comparative example, the shape after etching was slightly different for each wafer, and in some wafers, the thickness was tapered and one portion was thicker than the other. As described above, in the wafer holder for cleaning / etching of the present invention, etching occurs uniformly and the difference between wafers is small.

[0013]

As described in detail above, according to the wafer holder for cleaning / etching of the present invention, the uniformity and stability of the cleaning or etching process is increased, and the surface quality after the wafer process is stabilized.

[Brief description of drawings]

FIG. 1 is a view showing an example of a cleaning / etching wafer holder (external view) of the present invention.

FIG. 2 is a side sectional view of the holder shown in FIG.

3 is a cross-sectional view taken along the line SS 'of FIG.

FIG. 4 is a view showing another example of the cleaning / etching wafer holder (external view) of the present invention.

FIG. 5 is a side sectional view of the holder shown in FIG.

[Explanation of symbols]

 1 Side Plate 2 Wafer Support 3 Wafer 4 (a), 4 (b) Guide 5 Opening 6 Wafer Support 8 Opening 9 End Plate 10 Side Plate 11 Wafer Support 12 Wafer Rotating Support 13 Wafer 14 Opening

Claims (1)

[Claims] 1. A wafer cleaning or etching holder having a guide for holding a large number of wafers in an upright state, wherein the guides are provided parallel to each other and inclined in the same direction with respect to the vertical. A wafer holder for cleaning and etching, which is characterized in that