JPS6138608B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plasma apparatus used for etching semiconductor wafers.

In recent years, the superiority of the dry method as an etching method for semiconductor wafers has been recognized, and various plasma etching devices have come into use.However, as mass production equipment, these devices can be roughly divided according to their order of development and characteristics. There are two types:

1 A mounting jig (boat) with a large number of wafers placed upright at equal intervals is placed in a vacuum container into which a corrosive gas has been introduced, and a high-frequency voltage is applied from a counter electrode outside the container to generate plasma inside the container. A device that generates and performs etching.

2. As shown in Fig. 1, a wafer mounting jig (cassette holder) A is used to hold a large number of wafers C in an upright position in a row at equal intervals with the wafers C adhesively fixed to both sides of a wafer holding plate B made of Al. is placed in a vacuum container D made of quartz glass tube into which a corrosive gas is introduced, and a high frequency voltage (power supply E) of different polarity is applied alternately to these holding plates to create a voltage between all the holding plates. A device that generates plasma to perform etching.

The former method equipment is the earliest, and this method requires high voltage due to the large distance between the electrode plates, has the negative effect of sputtering effect due to ion particles, consumes a large amount of power, and requires a high concentration of etching gas. Since it is difficult to increase the etching rate, the etching speed is slow, and the uniformity of the plasma is also poor, resulting in poor etching uniformity and wafer warpage. The latter method device was proposed to remedy these deficiencies. However, even with the latter conventional method and equipment, the performance of keeping the etching gas concentration high and uniform is still insufficient, and the deterioration of the electrical properties of semiconductors due to ion particles still remains. It was hot.

The present invention aims to further improve and eliminate the deficiencies of the conventional plasma apparatus, and it is an object of the present invention to further improve and eliminate the defects of the conventional plasma apparatus. In a plasma apparatus in which wafers are arranged side by side and fixed on both sides of each wafer holding plate, one wafer on each side of each wafer holding plate is electrically connected to the wafer holding plate at an appropriate parallel interval. 1. A plasma apparatus characterized in that a conductive porous electrode plate is provided and plasma discharge is caused between two opposing porous electrode plates disposed between adjacent wafer holding plates.

The present invention will be explained below with reference to the drawings.

FIG. 2a shows a side view of the wafer mounting jig portion of the plasma apparatus according to the present invention, and FIG. 2b shows a partially cutaway front view thereof.

In the figure, the wafer holding plate 3 of the wafer mounting jig 2 used in the vacuum vessel 1 made of a quartz tube is usually made of Aluminum.
It is made of a disc-shaped material (a square plate shape is also acceptable), and has two sets of protrusions 5 from which projecting wafer support surfaces 4 inclined at an angle of about 45 degrees are provided on both sides of the lower side. With the wafers 6 adhesively supported on both sides of the surface 4, a large number of wafers (usually about 20) are placed in the cassette holder 7, which is made of quartz glass and connected to each other by two connecting members. As shown in FIG. protrusion 1
2 and the notch 13, and are engaged and held upright by a simple attachment/detachment method of inserting and leaving them stationary. The relative positions of the protrusions 12 and the notches 13, which are the lower engaging bodies of this holding plate, are formed so as to alternate from one plate to another, so that the opposing electrode can be inserted through the insertion hole 10 on the quartz jacket tube part 9. Protrusion 1 that contacts 8
The engagement by 2 applies a high frequency voltage with alternating electrical polarity to each holding plate. Note that the band plate-like portions 14 extending diagonally upward and along the tubes inside the two quartz jacket tube portions 9 are used to reinforce the linear shape of the tube portions and extend the lower part of the holding plate 3 at equal intervals. It is also provided as an engaging means for standing upright and supporting the device.

The wafer mounting jig composed of the above members corresponds to the conventional mounting jig shown in FIG. 1, but the wafer mounting jig according to the present invention includes various For each holding plate, two porous electrode plates (or mesh electrode plates) 15 made of plasma-resistant conductive material such as Al are additionally installed in parallel from both sides at an appropriate predetermined interval.

Each pair of porous electrode plates 15 is electrically connected to the retaining plate 3 located between them by a spacer 16, and is maintained at the same polarity and potential as the retaining plate 3. If the prepared wafer mounting jig is placed in a vacuum container made of a quartz glass tube and plasma etching is performed under the conditions shown in Figure 1, plasma discharge will occur between adjacent porous electrode plates of different polarities. Radicals such as fluorine, which are not generated between the wafer and the porous electrode plate, but are generated between the porous electrode plates of different polarity, move in and out through the porous passages of the porous electrode plate, causing a chemical reaction with the wafer surface. Therefore, it is possible to perform pure plasma etching without the spatter effect caused by harmful ion particles. Moreover, since the distance between the electrodes is close, the voltage can be low, and therefore power consumption is low, and the gas concentration can be increased and plasma with a more uniform concentration can be generated with lower power than conventional methods.
It is possible to provide a plasma apparatus that has advantages such as a low gas temperature that can reduce adverse effects on the resist, and a structure that allows easy heating and cooling from outside the container.

As mentioned above, the semiconductor wafer plasma apparatus according to the present invention can significantly improve product quality and production capacity, as well as reduce power consumption.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a plasma device using a conventional wafer mounting jig, and FIGS. 2a and 2b are partially broken views showing an embodiment of the wafer mounting jig used in the plasma device according to the present invention. Side view and A-
FIG. 3 is a partially cutaway front view showing the section A', and is a detailed view of the mounting portion of the wafer holding plate. 1... Vacuum container, 2... Wafer mounting jig, 3
... wafer holding plate, 6 ... wafer, 8 ... counter electrode bar, 15 ... porous (or mesh) electrode plate.

Claims (1)

[Claims] 1. A plasma in which a plurality of wafer holding plates in contact with electrode rods are arranged in a vacuum container so that reverse polarity voltages are alternately applied, and wafers are fixed on both sides of each wafer holding plate. In the apparatus, one porous electrode plate is provided on both sides of each wafer holding plate and is electrically connected to the wafer holding plate at an appropriate parallel interval, and is arranged between adjacent wafer holding plates. 1. A plasma device characterized in that the plasma device is configured to cause plasma discharge between two opposing porous electrode plates.