JPH05259053A - Spin coating on semiconductor substrate and device - Google Patents

Abstract

PURPOSE:To make thick the film of a coating layer and to dissolve a local unevenness of the film thickness by a method wherein an electric field is applied to the intermediate part, where the film thickness of the coating layer on a substrate becomes thin, of the substrate, an yield stress is given to a solvent and the viscosity of the solvent is increased. CONSTITUTION:A solvent 5 is dripped on the surface of a substrate 1 in a prescribed amount through a coating nozzle 4 and thereafter, the nozzle 4 is moved upward. Then, an upper electrode stage 9 is made to descend and positioned just above the substrate 1 and while a rotating stage 2 is rotated at high speed, the solvent 5 is spread on the whole surface of the substrate 1. During this spin coating, a prescribed excitation voltage is applied to doughnut-shaped lower electrodes 7 and doughnut-shaped upper electrodes 10, an electric field is applied to a coating layer 5a on the intermediate part of the substrate 1 and when a prescribed time elapses, the excitation voltage is stopped. Thereby, the viscosity of the solvent is increased, the film thickness of the coating layer is made thick, the uniformity of the film thickness of the coating layer can be increased and the quality and yield of the water can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for spin coating a semiconductor substrate.

[0002]

2. Description of the Related Art Conventionally, spin coating is one of the methods typically used for coating a semiconductor substrate such as a silicon wafer or a mask substrate with a solvent such as a photoresist or an adhesive wax. As shown in FIG. 3, this spin coating method is a coating nozzle in which an axis A is vertical on a semiconductor substrate (hereinafter simply referred to as a substrate) 1 which is suction-fixed to a rotary table 2 by a wafer chuck 3 of a vacuum type or the like. 4, the solvent 5 is dropped onto the central portion 1a of the substrate 1 and is rotated at a high speed in the arrow F direction via the spindle shaft 6 to utilize the centrifugal force acting on the solvent 5 to cause the solvent 5 to move.
It is a method of spreading the coating layer 5a over the entire surface to obtain a coating layer 5a having a uniform thickness. The film thickness of the coating layer 5a at this time is determined by the solvent concentration, the solvent volatilization rate, the spin rotation speed, and the like, and the solvent volatilization rate is affected by the environmental temperature, the humidity, the solvent temperature, the temperature of the substrate 1, and the like.

[0003]

However, in the conventional spin coating method as described above, the coating layer 5a is formed.
As shown in FIG. 4, there is a drawback that the film thickness is locally increased in the vicinity of the central portion 1a and the peripheral portion 1b of the substrate 1. That is, in the central portion 1a of the substrate 1, since the centrifugal force generated by the rotation is almost zero, the solvent 5 spreads poorly and the film thickness becomes thick, and at the peripheral portion, the peripheral speed becomes fast and the evaporation of the solvent is promoted. The film thickness increases.
On the other hand, there is a case where the film thickness becomes relatively thin in the middle part between the central part and the peripheral part.

By the way, as a countermeasure against such a thick film of the substrate, for example, in Japanese Unexamined Patent Publication No. 1-107867, the surface temperature distribution of the substrate is inclined so that the central part is made higher and gradually becomes lower toward the peripheral part. A method for making the film thickness uniform is disclosed. However, this method is effective when the change in the film thickness is linear, but has the drawback that the effect cannot be exhibited otherwise.

An object of the present invention is to provide a method and apparatus for coating a semiconductor substrate, which solves the above problems of the prior art.

[0006]

According to the present invention, in a method of spin-coating a semiconductor substrate fixed on a turntable with a solvent such as a photoresist or an adhesive wax, an electric field is applied to the solvent to give a yield stress. Is a spin coating method for a semiconductor substrate.

Further, the present invention is an apparatus for spin-coating a solvent such as a photoresist or an adhesive wax through a coating nozzle on a surface of a semiconductor substrate detachably fixed to the turntable, wherein the turntable is concentric. A semiconductor substrate having a donut-shaped lower electrode disposed above the rotary table, and an upper electrode table having a donut-shaped upper electrode disposed so as to face the lower electrode above the rotary table. Is a spin coating device.

[0008]

[Operation] According to the present invention, since an electric field is applied to the middle portion where the film thickness of the coating layer on the substrate is thin, the yield stress of the solvent is increased by this, so that the viscosity increases and the film thickness increases. Get thicker. Therefore, it is possible to eliminate local nonuniformity of the film thickness.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram schematically showing the configuration of the spin coating apparatus of the present invention. In the figure, the same members as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted. In the figure, 7 is a doughnut-shaped lower electrode disposed inside a rotary table 2 for fixing the substrate 1, and is concentric with a position corresponding to an intermediate portion 1c between the central portion 1a and the peripheral portion 1b of the substrate 1. And they are installed at almost equal intervals. A voltage is applied to the lower electrode 7 from an exciting power supply (not shown) via a power supply line 8 that runs inside the spindle shaft 6. Reference numeral 9 denotes an upper electrode base, inside of which a doughnut-shaped upper electrode 10 is arranged in the same manner as that of the rotary base 2 described above, and an exciting voltage is applied through a power supply line 12 which is wired inside the support shaft 11. Is applied.

First, a predetermined amount of the solvent 5 is dropped from the coating nozzle 4 onto the surface of the substrate 1, and then the coating nozzle 4 is moved upward. Next, the upper electrode base 9 is lowered and positioned immediately adjacent to the substrate 1, and the solvent 5 is spread over the entire surface of the substrate 1 while the rotary base 2 is rotated at a high speed of, for example, 4000 rpm. During this spin coating, a predetermined exciting voltage is applied to the lower electrode 7 and the upper electrode 10 to apply an electric field to the coating layer 5a of the intermediate portion 1c of the substrate 1. Further, when a predetermined time has elapsed, the excitation voltage is stopped and the upper electrode base 9 is moved upward to complete the spin coating, and subsequently, the coating nozzle 4 is lowered to prepare for the next spin coating of the substrate 1.

When a wax was spin-coated on a silicon wafer using the method of the present invention, a film thickness distribution as shown in FIG. 2 was obtained. For comparison, the film thickness distribution in the conventional method is also shown in the same figure. As is clear from this figure, the difference between the maximum value and the minimum value in the conventional method is 419 Å, whereas in the method of the present invention, it is 286 Å, which is about 32% smaller,
It can be seen that the uniformity is improved.

[0012]

As described above, according to the present invention, the viscosity of the solvent is increased by increasing the film thickness by applying an electric field to the solvent in the portion where the film thickness becomes thin so that the solvent has a yield stress. Uniformity can be improved, which can contribute to improvement of wafer quality and yield.

[Brief description of drawings]

FIG. 1 is a schematic diagram schematically showing the configuration of a spin coating apparatus of the present invention.

FIG. 2 is a characteristic diagram showing a film thickness distribution of a coating layer obtained by the present invention.

FIG. 3 is a schematic diagram showing a configuration of a conventional spin coating apparatus.

FIG. 4 is an explanatory diagram of a film thickness distribution of a conventional coating layer.

[Explanation of symbols]

 1 substrate (semiconductor substrate) 2 rotary table 3 wafer chuck 4 coating nozzle 5 solvent 5a coating layer 6 spindle shaft 7 lower electrode 9 upper electrode table 10 upper electrode 11 support shaft

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Claims (2)

[Claims] 1. A method of spin-coating a semiconductor substrate fixed on a turntable with a solvent such as a photoresist or an adhesive wax, wherein a spin stress is applied to the solvent by applying an electric field to the semiconductor substrate. Coating method. 2. An apparatus for spin-coating a solvent such as photoresist or adhesive wax on a surface of a semiconductor substrate removably fixed to a rotary table through a coating nozzle, wherein the rotary table is concentrically shaped like a donut. A spin coating apparatus for a semiconductor substrate, comprising: a lower electrode, and an upper electrode base having a donut-shaped upper electrode disposed above the rotary base so as to face the lower electrode. ..