JPS60215776A - Dry etching method - Google Patents

Abstract

PURPOSE:To dry-etch Al accurately and economically at a high speed by using a gaseous mixture consisting of BCl3, Cl2 and CCl4 as an etching gas. CONSTITUTION:When Al or an Al alloy is dry-etched, a geseous mixture consisting of BCl3, Cl2 and CCl4 is used as an etching gas and ionized with high frequency voltage of 13.56MHz in a vessel under reduced pressure to generate plasma. The surface of the metal is etched with the plasma. High speed and high accuracy etching can be economically carried out with a little etching gas at relatively high density of high frequency power in a small-sized apparatus.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a dry etching method, and particularly to a dry etching method suitable for etching aluminum and an alloy containing aluminum as a main component (hereinafter abbreviated as aluminum alloy). It is about the method.

[Background of the invention]

In the dry etching process of wafers, which is one of the steps in semiconductor production and manufacturing, high speed and precision etching must be achieved. Etching speed is an important factor that influences the productivity of semiconductor devices, and etching precision is an important factor that governs fineness for high integration.

In order to achieve high speed and precision etching at the same time, it is necessary to use an etching device suitable for the material to be etched.
In addition, a suitable etching method must be used.

The etching equipment used is one in which high-frequency power is applied under reduced pressure to one of a pair of parallel disk-shaped electrodes facing each other, and the wafer is etched by plasma generated by glow discharge generated between the electrodes. Ru. This type of etching gas is divided into two types: one that etches multiple wafers placed on an electrode at the same time, and the other that etches a single wafer placed on an electrode, each with its own unique characteristics. have.

On the other hand, when the material to be etched is aluminum or aluminum alloy, silicon tetrachloride (5iC14) is used as the etching gas, for example, as an etching method that combines high speed and precision.
A method using a gas mixture of boron trichloride (BCJ, ), chlorine (C/, ), and helium (He) has been proposed (R, F, Re1cheldefer, "S
ingle Wafer Plasma Btchin
g', 5solid8tate Tech, , 19
82-4). According to this, the etching speed is 100
To achieve etching speed and precision of approximately 0 nm/min or higher, the high frequency power density should be set to 2.2 = 3.
OW/a+f is much thicker than the normal case (need to be done. Also, each gas flow rate is 8i (J, 190~3008CCM, BCl, 10゛0~19
0 SCCM, CI! 1 is 100-190 SCCM
, He is 800 to 20,008 CCM, and their total flow rate is 1,190 to 26,808 CCM. This flow rate is
This is a large flow rate that is several times the gas flow rate in normal dry etching. .

As the high-frequency power density increases in this way, high-capacity high-frequency oscillation equipment is required, and the reaction chamber must be maintained at a certain reduced pressure. The displacement capacity of the pump must be increased or a special displacement pump with a high displacement capacity must be employed. All of these are direct causes of increasing the size and price of the dry etching apparatus including its auxiliary equipment.

[Purpose of the invention]

An object of the present invention is to provide a dry etching method that achieves high speed and precision in etching aluminum and aluminum alloys with a small high frequency power density and a small amount of etching gas, thereby making the dry etching apparatus compact and inexpensive. There is a particular thing.

[Summary of the invention]

The present invention provides BCl! , and CI! , 1 chlorine with a little sound
This method is characterized by using a gas mixed with tetrahalogenated carbon containing carbon as an etching gas, and converting the etching gas into plasma under reduced pressure to etch aluminum or an aluminum alloy. The present invention aims to achieve high speed and precision in etching aluminum and aluminum alloys using a small amount of etching gas.

[*Example of invention]

After extensive research into etching methods for aluminum and aluminum alloys, we found that BC1! .

0.7 to 1.5 W/cIl depending on the mixed gas of and C/.
With a small high frequency power density of 808 CCM and a small amount of etching gas of 808 CCM, it is possible to achieve a high etching speed of approximately 1000 nm/min or more, although the etching precision is lacking, and furthermore, BC1!
, and CI! It has been found that etching speed can be maintained and etching precision can be achieved with a mixed gas of carbon 110 containing at least one chlorine element.

That is, a high frequency power of 13.56 MHz was applied to one of the electrodes installed in parallel facing the reaction chamber to be evacuated, and a single wafer patterned with photoresist was placed on the electrode. and the gas flow rate Q of carbon tetrachloride (CC/4) added to the mixed gas of BCl and C4.
Etching was performed by changing . As a result, the first
Figure 2 was obtained.

In this case, the high frequency power density Wd is 1.0 W/
d, gas pressure P is 26.6 Pa, electrode spacing H is 30 m
+BC4+C4 total gas flow rate Q2 is 808CCM, B
cl! , +cz, the total gas flow rate Q is 808 CCM,
BCl.

+CI! The ratio Q of the gas flow rate of CZffi to the total flow rate Q of * is constant at 50-.

In Figure 1, the horizontal direction quantitatively shows the precision of etching.
That is, the etching speed ratio V, (V, = τ) between the etching speed h in the pattern line width direction and the etching speed h in the vertical direction, that is, in the plate thickness direction, is as follows:
CCI! , in the case of no additive, it is about 0.3, which lacks the precision of etching, but CCI! As the gas flow rate of 4 is increased, the etching speed ratio V becomes a small noise, and when the gas flow rate of CC1!4 is about 6 SCCM, the etching speed ratio V is the smallest at about 0.03, and the etching precision is sufficient. achieved. CCI! If the gas flow rate of 4 is further increased, the etching speed ratio v becomes thicker, for example, CC1!
When the gas flow rate of No. 4 was 2080CM, the etching speed ratio V was approximately 0.2.

In FIG. 2, the etching speed V is CCI! In the case of no additive 4, the etching speed is approximately 1100 nm/min, and the etching speed is sufficiently high as it is. At 680CM, the etching speed V is approximately 130
0 nm/min, which further improves the etching speed.

As shown in FIGS. 1 and 2, in this case, 1. OW/c
For example, CC1!4 with a small high frequency power density of d.
When the gas flow rate is 68 CCM, the etching speed ratio V can be as small as about 0.03 with a small amount of etching gas of 868 CCM, and the etching speed V can be made as low as about 1300 nm/min, which improves the high speed and precision of etching. I was able to achieve this.

With the dry etching method of this embodiment, high speed and precision etching of aluminum and aluminum alloys can be achieved with a small high frequency power density and a small amount of etching gas, so there is no need to increase the capacity of the high frequency oscillation equipment. There is no need to increase the evacuation capacity of the evacuation pump or to employ a special evacuation pump with a high evacuation capacity, so the dry etching apparatus can be made smaller and less expensive.

Furthermore, since the high frequency power density is small, damage to the photoresist can be suppressed.

In this example, CCI! is used as carbon tetrahalide containing at least one chlorine. 4 is used, but in addition, CC1!4 chlorine and fluorine substitution compounds containing at least one chlorine, ie, CF(1'/, CF), are used.

C4, CFS C1 is also effective in achieving etching precision. Further, the aluminum alloy includes copper, silicon, or an aluminum alloy containing several of these.

〔Effect of the invention〕

As explained above, the present invention is based on B C/s and C/.

By using a gas mixture of carbon tetrahalide containing one chlorine and a small amount of chlorine as an etching gas, and turning the etching gas into plasma under reduced pressure to etch aluminum or aluminum alloy, a small high frequency power density and High speed and precision etching of aluminum and aluminum alloys can be achieved with a small amount of etching gas, so there is no need to increase the capacity of high frequency oscillation equipment.
There is an effect that the dry etching apparatus can be made smaller and cheaper without increasing the evacuation capacity of the evacuation pump or using a special evacuation pump with a high evacuation capacity.

[Brief explanation of the drawing]

Figure 1 shows the gas flow rate Q of CCZ4 obtained by implementing the present invention.
, and the etching speed ratio V, Figure 2 shows the same CCI! 4 is a relationship diagram between the gas flow rate Q1 and the etching speed V in No. 4. FIG. Ql... Gas flow rate of CC1!4, ■,...
...Etching speed ratio, ■...Etching speed, Wd...High frequency power density Qs BCls
Total gas flow rate of 10” ○Agent Patent attorney Akio Takahashi 390-

Claims (1)

[Claims] 1. A gas obtained by heating boron trichloride, chlorine, and carbon tetrahalide containing at least one chlorine is used as an etching gas, and the etching gas is turned into plasma under reduced pressure to produce aluminum or aluminum. Naru is a dry etching method characterized by etching an alloy whose main component is aluminum. 2. The tri-etching method according to claim 1, wherein the carbon tetrahalide is carbon tetrachloride.