JP2000091222A - Resist coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resist coating apparatus for sucking and fixing a warped wafer to a spin head with sufficient suction force without a crack or a split of the wafer, while the wafer is prevented from spinning out during rotation of the spin head. SOLUTION: A resist coating apparatus has a spin head having a rotatably round shape and a suction groove 13 opened on an upper face. A silicon wafer 18 used for a semiconductor is coated with resist by vacuum suction. In this case, the suction groove 13 has an inner circumferential part as a vertically movable part 21. The inner circumferential part moves in accordance with the shape of the warped wafer, so a vacuum suction groove 13 and the wafer 18 are put in contact completely. In addition, by sticking an elastic material to a suction face of the spin head, a junctional area can be increased to improve suction. Then, the wafer 18 can be prevented from spinning out during the rotation. At the same time, stress for extending the wafer in direction reverse to the warp can be reduced, and a crack or a split in the wafer 18 caused by vacuum suction can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist coating apparatus mainly used for coating a resist on a silicon wafer for semiconductors, and more particularly to a spin head structure.

[0002]

2. Description of the Related Art Spin coating of a resist is one of means for applying a resist to a silicon wafer for a semiconductor by photolithography. This method uses a coating device called a spin coater to vacuum-suction a wafer horizontally on a flat plate called a spin head, which has a structure that sucks the wafer in vacuum, and then drops a resist on the wafer to form a spin head. This is a method of applying the resist uniformly by rotating the resist.

A glass passivation mesa diode is manufactured by the following procedures (1) to (9). FIG.
FIG. 7 shows a manufacturing process of the glass passivation mesa diode. Although a plurality of diode chips are originally formed on one wafer, a cross-sectional view of one chip is shown here.

(1) As shown in FIG. 6A, a diffusion N-type silicon substrate comprising an N ⁻ layer (low concentration layer) 1 and an N ⁺ layer (high concentration layer) 2 is prepared.

(2) As shown in FIG. 6B, a P-type diffusion layer 3 is formed in the low-concentration layer 1 of the silicon substrate by thermal diffusion of boron (B), which is a P-type impurity, and is parallel to the surface. PN
Form a bond. Thereby, a PN diode structure is formed.

(3) Next, as shown in FIG. 6C, the silicon substrate is thermally oxidized to form oxide films 4 and 5, and a mesa groove is formed on the P-type diffusion layer 3 by photolithography. Opening 6 is formed.

(4) Further, as shown in FIG. 6D, the oxide film 4 is used as a mask to etch the P-type diffusion layer 3 from the P-type diffusion layer 3 through the PN junction, the low-concentration layer 1 and the high-concentration layer 2
To form a mesa groove 7.

(5) Next, as shown in FIG.
A part of the oxide film 4 at the opening of the mesa groove 7 is removed by photolithography to form an opening 8.

(6) Next, as shown in FIG. 7A, the mesa groove is filled with glass powder 9 for passivation.
As a result, the glass powder 9 completely covers the opening and reaches the oxide film 4.

(7) Next, as shown in FIG.
The passivation glass 10 is formed by firing at a temperature of about 50 ° C. Here, since the thermal expansion coefficient of glass is larger than the thermal expansion coefficient of silicon, the silicon wafer is warped upward during this heat treatment.

(8) Next, the oxide film 4 is removed, and FIG.
The state shown in FIG.

(9) Next, as shown in FIG. 7 (d), the electrodes 11 and 12 are formed to complete the diode.

However, during this process, in order to perform patterning as shown in FIG. 7D, vacuum suction grooves were formed on the suction surfaces 14, 15 and concentric circles of the wafer as shown in FIG. It is necessary to apply a resist by using a spin head. However, since the wafer is warped, as shown in FIG.
A gap is formed between the spin heads 4 and 15 so that the vacuum suction groove 13 cannot be closed.
However, there is a problem in that the wafer cannot be sucked in parallel and the wafer 18 cannot be sucked in vacuum, or even if the wafer 18 can be sucked, the wafer jumps out of the spin head during spin coating.

Further, if the vacuum suction force is increased to force the suction, the wafer is stretched to the side opposite to the warpage, and there is a problem that the glass in the mesa groove or the crack of the wafer is generated or cracked. .

[0015]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and enables a warped wafer to be attracted and fixed to a spin head with a sufficient suction force, thereby preventing the wafer from popping out during rotation of the spin head. It is another object of the present invention to provide a resist coating apparatus that does not cause cracks or cracks in a wafer.

[0016]

SUMMARY OF THE INVENTION The present invention relates to a rotatable circular spin head having a suction groove formed on an upper surface thereof and suctioning a semiconductor silicon wafer to be coated with a resist by vacuum suction. Wherein the part of the suction surface of the wafer is movable.

Further, the present invention is the resist coating apparatus according to the above-mentioned resist coating apparatus, wherein an elastic material is adhered to the suction surface of the wafer of the spin head.

That is, the resist coating apparatus of the present invention has a suction groove which is opened on the upper surface of a rotatable circular spin head, and sucks a silicon wafer to be coated with a resist onto the spin head by vacuum suction. In the above, the outer peripheral portion and the inner peripheral portion are made independent from each other with the vacuum suction groove of the spin head as a boundary, the outer peripheral portion is fixed, and the inner peripheral portion is vertically movable with a certain elastic force.

[0019]

FIG. 1 shows a first embodiment of the present invention.
Shown in As shown in FIG. 1, in the resist coating apparatus according to the first embodiment, the suction surfaces 14, 15 of the spin head are divided into two parts by a vacuum suction groove 13, and the outer peripheral part is fixed to the main body. However, the inner peripheral portion is independent, and the suction surface 15 of the inner peripheral portion has a certain elastic force by a spring force when a force is applied, and has a vertically movable structure.

FIG. 2 shows an example of use of the present embodiment. As shown in FIG. 2, the circular thin wafer 1
When the wafer 8 is placed on the suction groove 13 and vacuum-sucked through the suction groove 13, the wafer warped downward by the suction force is drawn toward the suction groove 13 by the vacuum suction force, and the corners 16 and 17 of the suction surface are drawn. Moves to close (the wafer touches the outer part of the suction groove). At this time, the force of closing the suction groove 13 pushes down the suction surface 15, and the wafer 18 comes into contact with the corner portions 16 and 17 to completely close the suction groove 13, and the wafer and the spin head are completely removed by the vacuum suction force. Fixed.

Here, the wafer 18 and the suction surfaces 14, 15
Even if there is a gap between the wafers, the wafer is completely fixed to the spin head because the suction groove is completely closed, and the wafer is moved in the opposite direction to the warp by the movable suction surface 15. Since the wafer is not forcibly stretched, cracks and cracks in the wafer can be prevented, and the wafer is prevented from jumping out of the spin head during spin coating of the resist.

Further, by providing the vacuum suction groove 19 on the suction surface 15, the suction force to the wafer 18 can be further improved.

FIG. 3 shows a second embodiment of the present invention.
As shown in FIG. 3, the resist coating apparatus according to the second embodiment is obtained by dividing the suction surface of the first embodiment into three and providing three suction grooves 13, 19, and 22. Thereby, the attraction force can be further improved.

FIGS. 4 and 5 show a third embodiment of the present invention. As shown in FIG. 4, the resist coating apparatus according to the third embodiment differs from the first embodiment in that the suction surfaces 14 and
An elastic material 23 having an elastic force is adhered on the upper surface of the substrate 15 with a certain thickness. As shown in FIG. 5, when the wafer 18 is placed on the spin head and vacuum-sucked, the wafer 18 performs the same movement as in the first embodiment, and the same effect can be obtained. Since the material 23 is attached, the elastic material 23 and the wafer 18
The elastic material 23 is deformed into the shape of the wafer 18 at the portion where the wafer comes into contact with the wafer 18, and closely fits the wafer 18, particularly, the bonding area at the corners 25 and 26 increases, and the suction force between the spin head and the wafer further increases. Further, the stress for expanding the wafer in the direction opposite to the warpage can be further reduced.

In the present embodiment, one movable portion is provided. However, a plurality of suction surfaces of the movable portion are provided, and a plurality of suction surfaces of the movable portion are further provided on an inner peripheral portion of the suction surface of the movable portion. Provided,
By adopting a structure that fits a warped wafer, the suction force can be further improved. Further, by providing a plurality of vacuum suction grooves concentrically on the suction surface, the suction force can be further improved. Further, the size of the suction surface of the fixed part and the movable part can be arbitrarily changed.

Further, in the present embodiment, the movable portion is constituted by using a spring, but other structures may be used as long as the elastic member has an elastic force. That is, the elastic body of the movable portion is not limited to a spring, but may be another elastic body, one using air pressure, or one using an electric sensor.

[0027]

According to the present invention, the inner peripheral portion of the spin head moves according to the shape of the warped wafer, and the vacuum suction groove and the wafer come into close contact with each other. By adhering the material, the bonding area can be further increased and the suction force can be improved, so that the wafer does not fly out during rotation of the spin head, and the stress that spreads the wafer in the opposite direction to the warpage can be reduced. In addition, damage such as cracks and cracks on the wafer due to vacuum suction force is eliminated.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a spin head according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a suction state between a spin head and a wafer according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a suction state between a spin head and a wafer according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a structure of a spin head according to a third embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a suction state between a spin head and a wafer according to a third embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a manufacturing process of the diode.

FIG. 7 is a cross-sectional view illustrating a manufacturing process of the diode.

FIG. 8 is a sectional view showing the structure of a conventional spin head.

FIG. 9 is a cross-sectional view showing a conventional spin head and a wafer suction state.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 N ^- layer (or low concentration layer) 2 N ⁺ layer (or high concentration layer) 3 P-type diffusion layer 4,5 Oxide film 6,8 Opening 7 Mesa groove 9 Glass powder 10 Passivation glass 11,12 For electrodes Metal 13, 19, 22 (Vacuum) suction groove 14, 15 Suction surface 16, 17 Corner of (suction surface) 18 Wafer 20 Spring 21 Movable portion 23 Elastic material 25, 26 Corner of (elastic material)

Claims (2)

[Claims] 1. A resist coating apparatus, comprising: a rotatable circular spin head having a suction groove formed on an upper surface thereof and having a spin head for suctioning a semiconductor silicon wafer to be coated with a resist by vacuum suction. A resist coating apparatus, wherein a part of a suction surface of a wafer is movable. 2. The resist coating apparatus according to claim 1, wherein an elastic material is stuck to a suction surface of said wafer of said spin head.