JPH06224177A - Semiconductor manufacturing apparatus - Google Patents

Abstract

PURPOSE:To provide a semiconductor manufacturing apparatus wherein a semiconductor wafer is anisotropically etched excellent in uniformity throughout its surface. CONSTITUTION:A semiconductor manufacturing apparatus is composed of an etching tank 7 filled with alkaline solution 11, a heating tank 10 covering the base and all the side face of the etching tank 7, a heater 13 which heats heating fluid 12 filled into the heating tank 10, and chuck means 20 which are provided inside the etching tank 7 in a freely detachable manner and where a semiconductor wafer 1 is horizontally placed respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus for anisotropically etching a semiconductor wafer to form V-grooves for element region separation when manufacturing a high withstand voltage IC or the like with dielectric isolation. It is a thing.

[0002]

2. Description of the Related Art In an IC or the like which is required to have a high breakdown voltage, a dielectric isolation for completely isolating an element region is performed. As shown in FIG. 3, this dielectric isolation means that (a) the back surface of the semiconductor wafer (1) is anisotropically etched using the oxide film (2) as a mask so as to surround the element region (3). After forming a V-groove (4) on the substrate, (b) forming an oxide film (5) on the subsequently formed V-groove (4), polysilicon (6) is deposited, and (c) after that, a semiconductor wafer ( This is a method in which the surface of 1) is polished until the tips of the V-grooves (4) appear, and a large number of element regions (3) are formed by insulation separation using polysilicon (6) as a support.

The element region separating V groove (4) is formed by anisotropic etching. As shown in FIG. 4, the apparatus for anisotropic etching has a two-layer structure consisting of an etching tank (7) and a heating tank (10). (1
1) is put and the heating fluid (12) is placed in the outer heating tank (10).
The heating fluid (12) is heated by the heater (13), and the alkaline solution (1
1) is being heated. Then, the etching is performed by arranging the masked semiconductor wafers 1 side by side and accommodating them in a large number in a carrier (14) and submerging the semiconductor wafers (1) together with the carrier (14) into an etching tank (7).

[0004]

[Problems to be Solved by the Invention] Semiconductor wafer (1)
When anisotropic etching is performed on the substrate, as shown in FIG. 5, if a mask (15) that matches the shape of a desired element region is formed, the etching rate in the (111) direction (side etching direction) is increased. Because of the high speed, as shown in FIG. 6, a large amount of the corner portion (16) of the element region (3) is etched, the distance to the insulating layer is shortened, and the pressure resistance is lowered. Therefore, usually, as shown in FIG. 7, the corner portion (15a) of the mask (15) is formed large so as to have a desired shape at the time of etching.

However, the conventional etching apparatus heats the entire alkaline solution (11) with the heating fluid (12),
Although the whole of the alkaline solution (11) is heated uniformly without causing convection, the temperature on the upper side is inevitably higher than that on the lower side. Since the semiconductor wafers (1) are erected side by side in such an alkaline solution (11), the temperature difference between the upper and lower portions of each semiconductor wafer (1) causes a difference in etching rate,
The amount of side etching of the element region (3) varied within the plane of the semiconductor wafer (1). Further, bubbles of the reaction gas are generated during etching, but the generated amount varies in the plane depending on the reaction amount, and the bubble break also differs between the upper and lower sides of the semiconductor wafer (1), and the bubbles hinder the etching.
This also contributed to the variation in the side etch amount.

An object of the present invention is to provide a semiconductor manufacturing apparatus which eliminates a temperature difference of an alkaline solution in a plane of a semiconductor wafer during etching and can perform etching under the same condition that bubbles are easily broken.

[0007]

According to the present invention, there is provided an etching tank for containing an etching solution, a heating tank for covering a bottom portion and a side portion of the etching tank, and a heater for heating a heating fluid contained in the heating tank. , A plurality of chuck means that are provided so as to be able to move in and out of the etching tank and horizontally hold and hold a semiconductor wafer on the upper surface thereof.

In addition, there is also one in which the etching tank is vibrated by an ultrasonic wave generator.

[0009]

In the semiconductor manufacturing apparatus described above, the semiconductor wafers are laterally arranged and immersed in an alkaline solution for etching, so that the semiconductor wafers are kept at the same height in the plane and a temperature difference occurs in the planes. Absent. In addition, the amount of bubbles generated by the reaction is the same on the wafer surface, and variations in etching do not occur.

Further, if the etching bath is vibrated by the ultrasonic generator, the bubbles on the surface of the semiconductor wafer are improved,
The reaction is accelerated.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, the semiconductor manufacturing apparatus has a two-chamber structure including an etching bath (7) having a shallow bottom and a heating bath (10) surrounding the etching bath (7). Put the alkaline solution (11) for etching into 7),
The heating fluid (12) is put into the heating tank (10). Further, the heating tank (10) is provided with a heater (13), and the heating fluid (1
2) is designed to be heated. Further, the etching tank (7) is provided with a plurality of chuck means (20) for holding the semiconductor wafer (1) sideways. The chuck means (20) is of a type that performs vacuum suction, for example,
The suction surface (21) is moved up and down by an appropriate lifting means (not shown) so as to move in and out of the etching tank (7).

In the above semiconductor manufacturing apparatus, when the suction surface (21) of each chuck means (20) is lifted above the etching tank (7) and the semiconductor wafer (1) is placed on the suction surface (21), This is vacuum-adsorbed, and then, the semiconductor wafer (1) which is descended and adsorbed is immersed in an alkaline solution (11) in an etching tank (7) to perform etching. After etching, chuck means (20)
Is raised and pure water is applied to stop the etching, and the semiconductor wafer (1) is taken out from the etching tank (7).

Further, as shown in FIG. 2, an ultrasonic wave generator (22) is provided in the heating tank (10), and the etching tank (7) is vibrated during the etching process by the ultrasonic wave generator (22). Some have been done. In this case, since the semiconductor wafer (1) is vibrated, the bubbles generated by the reaction can be quickly separated from the surface of the semiconductor wafer (1), and the reaction is accelerated.

[0015]

According to the present invention, even if the etching alkaline solution in the etching tank has a temperature difference between the upper and lower sides, the semiconductor wafer is laid sideways and immersed in the alkaline solution in the etching tank for etching. The entire surface of the semiconductor wafer will react at the same temperature. Therefore, the entire semiconductor wafer is uniformly etched,
Moreover, the amount of bubbles generated is uniform over the entire surface, the reaction does not fluctuate, and the side-etch fluctuation in the element region after etching is eliminated.

Further, if the etching bath is vibrated by the ultrasonic generator, the breakage of bubbles generated on the surface of the semiconductor wafer is improved, so that the reaction is promoted and more stable etching can be performed.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a semiconductor manufacturing apparatus according to the present invention.

FIG. 2 is a schematic sectional view showing another embodiment of the semiconductor manufacturing apparatus according to the present invention.

FIG. 3 is a view showing a process of forming an element region by dielectric isolation, and a to c are cross-sectional views of a semiconductor wafer in each process.

FIG. 4 is a schematic sectional view showing a conventional semiconductor manufacturing apparatus.

FIG. 5 is a plan view showing the shape of a mask during etching.

FIG. 6 is a plan view of a semiconductor wafer showing a defective product.

FIG. 7 is a plan view showing the shape of a mask used for etching.

[Explanation of symbols]

 1 Semiconductor Wafer 7 Etching Tank 10 Heating Tank 11 Alkaline Solution 12 Heating Fluid 13 Heater 20 Chuck Means 22 Ultrasonic Generator

Claims (2)

[Claims] 1. An etching bath containing an etching solution,
A heating tank that covers the bottom and sides of the etching tank, a heater that heats the heating fluid contained in the heating tank, and a heater that can be moved in and out of the etching tank. A semiconductor manufacturing apparatus comprising a plurality of chucking means for holding. 2. An etching bath containing an etching solution,
A heating tank that covers the bottom and sides of the etching tank, a heater that heats the heating fluid contained in the heating tank, and a heater that can be moved in and out of the etching tank. A semiconductor manufacturing apparatus comprising: a plurality of chucking means for holding the ultrasonic wave; and an ultrasonic wave generator for vibrating the etching bath.