JPS61127875A - Etching method of al - Google Patents

Abstract

PURPOSE:To execute excellent anisotropic etching of Al with high throughput by specifying the ratio of the space between flat plate electrodes with respect to the diameter of a high-frequency electrode at a specific value or below and subjecting the Al to dry etching under adequate conditions. CONSTITUTION:An etching gas contg. <=40% CCl4 and BCl3 and having >=10Pa pressure is used and the electric power density of the high-frequency electric power area of the flat plate electrodes is set at >=0.2W/cm<2> in a method for the dry etching of the above-mentioned Al by disposing a pair of the flat plate electrodes facing each other in a reaction vessel, imposing a substrate provided with a surface Al film on one of the electrodes, grounding the same, impressing the high-frequency electric power to the other electrode and introducing the prescribed etching gas into the above-mentioned vessel. The space between the above-mentioned two electrodes is set at <=1/5 the diameter or short diameter of the flat plate electrode to which the high-frequency electric power is impressed. The etching of the Al at the low side etching rate is executed with the high throughput by the above-mentioned anode couple method.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an Al dry etching method using a parallel plate plasma etching apparatus used in the manufacture of semiconductor devices.

(Prior art and its problems) In the past, wet etching methods using chemicals have generally been widely used in the manufacture of semiconductor devices and electronic components, but wet etching methods have many drawbacks such as side etching. be. Therefore, as it becomes necessary to form finer patterns to improve the degree of integration, the so-called dry etching method, which does not use chemical solutions, has been proposed as an etching method. Plasma etching methods using parallel plate electrodes, in which targeted etching proceeds simultaneously, have been attracting much attention. In this method, opposing parallel plate electrodes are arranged in a reaction vessel I, an object to be etched (hereinafter referred to as the substrate) is placed on one of the plate electrodes, and a predetermined etching process is performed on the parallel plate electrodes in a gas atmosphere at a predetermined pressure. Etching is performed by applying high frequency power to generate plasma.

Conventionally, when etching A4 size on a substrate using a parallel plate type plasma etching apparatus, high frequency electricity has been widely used due to its advantages.

FIG. 1 shows a schematic diagram thereof.

However, in this figure, one of the parallel plate electrodes 2 and 3 facing each other in the grounded reaction vessel 1 is electrically connected to the reaction vessel 1, and the other 3 is connected by a wiring 5 penetrating an insulator 4. It is electrically connected to a high frequency power source 6 outside the reaction vessel 1. 7 is a funodenser, and 8 is a discharge plasma. The processed substrate 9 is placed on the flat electrode 3 .

FIG. 2 (fat) is a graph showing the etching characteristics of the apparatus shown in FIG. 1 (al), and shows that the amount of side etching is small.

However, this cathode couple system has drawbacks such as a complicated electrode structure and reduced throughput when automating substrate transport, and this has become a major problem. On the other hand, it has attracted attention because it uses an anode couple method in which a substrate is placed on a ground electrode. Figure 1 (
bl K shows its schematic diagram. However, the symbols and names of each member in this figure correspond to FIG. 1 (at).

However, this 7-node pull method has the problem that the acceleration of ions by the electric field is weak, and the reaction with radicals becomes the main reaction, making the etching highly isotropic, easily causing side etching, and deteriorating processing accuracy. .

FIGS. 2 and 2) are graphs showing the etching characteristics of the apparatus shown in FIG.

(Objective of the Invention) An object of the present invention is to solve the above-mentioned conventional problems and provide a method for obtaining an excellent heterogeneous etching of AI using a seven-node couple method with high throughput.

(Structure of the Invention) The present invention provides a seven-node couple method in which the interval between the flat electrodes is 115 or less of the diameter of the flat electrode on the side to which high-frequency power is applied (or the minor axis if the flat electrode is not disc-shaped). CC and BCl3 are used as etching gases, and the CCA'4' CCl4 gas amount is 40% or less, the gas pressure is 10 Pa or more, and the power density per area of the planar electrode of the applied high-frequency power is 0. The above object has been achieved by the Al $etching method in which the ratio is set to .2w/i or more.

(Example) Hereinafter, the present invention will be described in detail using an example and based on the drawings.

First, using the seven-node couple system of [Z(b)], for example, as shown in FIG.
A substrate 9 is a sample on which an AI film 12 is formed by sputtering or the like on the 0 surface, and a resist pattern film 13 is further applied thereon, and high frequency power is applied to the plate electrode 2, the interval d between the three voices. B CJ
3 and CCA4 were used as etching gases, CCl4 gas was used at a total gas flow rate of 25 cm, the pressure of the etching gas was set at 15 Pa, and the power density per area of the flat plate electrode of the applied high-frequency power was set at 0.3 w/ffl. When plasma etching was performed, the etched shape became as shown in Figure 4 (at). In other words, an excellent anisotropic shape without side etching was obtained.The etching rate at that time was 1000 etchings/lea. But at this time,
If the other conditions remain the same and the distance d between the plate electrodes is increased to 1/4 of the diameter l of the plate electrode on the side to which high-frequency power is applied, as shown in Figure 4(b), Deep side etching occurs, significantly reducing dimensional accuracy. This is d
By decreasing the value of the ratio of /l, the slope of the electric field increases and - due to the electric field, side etching tends to occur when the CCl4 gas is 25% or more of the total gas flow rate, and side etching is more likely to occur when the ratio is 40% or more. The etching becomes extremely impractical. 40 inches is the upper limit for CCl4 gas contamination. If the amount of CCl4 gas mixed in is less than 25%, the etching rate will decrease due to the coo-teating effect, and if it is less than 15%, the etching rate will drop so much that it will soon become unusable.

CCI! A preferable value is about 25 inches of the total gas flow rate of 4CCl4 gas. Furthermore, when the other conditions are set to 11°C and the etching gas pressure is lower than 15P+1, the side etching cup increases rapidly as shown in FIG.
It was also found that if the pressure is less than 10 Pa, it becomes impossible to use the amount of tinging very quickly. A value of 15 Pa or more is preferable in this case.Furthermore, keeping the song conditions as they are, When the power density per area of one high-frequency planar electrode applied to the electrode is lower than 0.3 W/, l, side etching blue increases, and when it is lower than o, 2 W/, ffl, the amount of side etching increases significantly. It was found that the power density was 0.3W/
The preferable value was d or more.

Al with less side etching due to anode couple method
The conditions for obtaining etching are as explained above, and by observing the above conditions, etching quality comparable to that of the cathode couple method can be ensured. That is, in an anode couple type device, the interval between the plate electrodes is set to 115 or less of the diameter of the electrode on the side to which high-frequency power is applied (if the electrode is not disc-shaped, its short diameter), and BCl3 is used as the etching gas. and CCl4, and the total gas flow gH(7') 4
High frequency 1. Applying an etching gas pressure of 10 Pa or more at a pressure of 10 Pa or less. The force density is set to 0.2 W/c+d or more.

This makes it possible to obtain excellent anisotropic etching at a high etching speed.

(Effects of the Invention) The method of the present invention makes it possible to manufacture LSI chips, electronic components, etc. with fine patterns with high processing accuracy and high throughput.

[Brief explanation of the drawing]

FIG. 1 (+L) is a schematic diagram of a cathode couple type device, and FIG. 1(b) is a schematic diagram of an anode couple type device. Figure 2 (
at is a graph showing the relationship between the etching gas pressure and the amount of side etching in the cathode couple device; FIG. 2 is a graph showing the relationship between the etching gas pressure and side etching after the anode couple; Semiconductor before chipping; cross-sectional view of 5th board, No. 41xl fa
l is a cross-sectional view when anisotropic etching is performed on the substrate described in ^1■, FIG. In the double-pull method, the relationship between the side etching percentage and the ratio of the spacing between electrodes (abbreviated as electrode spacing in the figure) and the electrode diameter on the side to which high-frequency power is applied (abbreviated as electrode diameter in the figure), FIG. 6 is a graph showing the relationship between the side etching amount and the etching gas pressure, and FIG. 7 is a graph showing the relationship between the side etching amount and the applied high frequency power density.

Claims (1)

[Claims] One of the opposing flat plate electrodes arranged in the reaction vessel is grounded, high frequency power is applied to the other, and Al on the surface of the substrate placed on the ground side flat plate electrode is dry etched with a predetermined etching gas. In the etching method, the etching gas is C Cl_4 and B C
1_3, and CCl_4 is 40% or less of the total flow rate of the etching gas, and the pressure of the etching gas is 10%.
Pa or more, the power density per area of the plate electrode of the applied high-frequency power is set to 0.2 W/cm^2 or more, and the interval between the plate electrodes is set to the diameter of the plate electrode on the side to which the high-frequency power is applied (plate electrode 1. A method for etching Al, characterized in that the width is 1/5 or less of the minor axis (if it is not disc-shaped).