JPH01140725A - Dry etching of al-si-cu alloy - Google Patents

Abstract

PURPOSE:To increase an etching speed ratio and to enhance mass productivity by a method wherein a ring composed of an insulating material is installed at a peripheral part of a lower-part electrode of a magnetron reactive ion etching apparatus and an Al-Si-Cu alloy is etched by generating a plasma of a chlorine-based gas. CONSTITUTION:A ring 18 composed of an insulating material is installed at a peripheral part of a lower-part electrode 12 of a magnetron RIE apparatus; an object 19 to be etched is placed on the upper part of the lower-part electrode 12. An etching operation is executed by using a reaction gas. By this setup, it is possible to lower a cathode drop voltage; as a result, it is possible to lower a surface temperature of a wafer during the etching operation; it is possible to increase a value of an Al-Si-Cu alloy/a resist.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is an AI-
The present invention relates to a dry etching method for Si--Cu alloys, and particularly to a method for manufacturing semiconductor integrated circuits.

Conventional Technology In recent years, as a dry etching method for AI-Si-Cu alloys, magnetron reactive ion etching (hereinafter referred to as magnetron RIE) method using high-frequency discharge applying a magnetic field, which causes less damage due to plasma, has been studied. (For example, [Semiconductor World J 198
July issue, P181-186. P147-158).

Referring to the drawings below, the conventional Al-Si-
An example of magnetron RIE of Cu alloy will be explained. Figure 4 shows an apparatus used in the conventional magnetron RIE method. A chlorine-based reaction gas is introduced into the reaction chamber 1 from the gas supply port 2, while an exhaust gas is connected to an exhaust means (not shown). Exhaust air from the port 8 to reduce the pressure to about 1 O Torr, apply high frequency RfIt pressure from the high frequency power source 5 to the lower electrode 4, and connect the lower electrode 4 and the upper
, and a magnet 7 is disposed above the upper electrode 6 to generate a magnetic field orthogonal to the electric field to increase the plasma density, and the object to be etched 8.
etching.

Problems to be Solved by the Invention In the conventional method described above, the plasma density increases due to the installation of the magnet 7, and
Since the mean free path of gas molecules becomes longer due to the high vacuum near rr, high-speed etching with high anisotropy is possible. -Cu etching speed/resist etching speed, hereinafter referred to as AI-3i
-Cu/v cis) t) If the value is as small as Cu2/x or less, there is a problem that mass productivity is low.

The present invention solves the above-mentioned problems.
The object of the present invention is to provide a dry etching method for an Al-3i-Cu alloy that can reduce the Cu/resist ratio to 8/1 or more, which is required for mass production.

Means for Solving the Problems In order to solve the above problems, the Al-3i-
The method of dry etching a Cu alloy involves providing a ring made of an insulating material around the lower electrode of a magnetron reactive iodine etching device, and forming a plasma of chlorine gas to etch the Al5i-Cu alloy.

Operation The present invention has the above-described configuration, and the cathode drop voltage (hereinafter, V
It is written as dc'. ), and as a result, the surface temperature during etching can be lowered, and the value of the Al-8i-Cu alloy/resist can be increased.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic rlfr side view of an apparatus used in a dry etching method for an AI-3i-Cu alloy according to an embodiment of the present invention. In Figure 1, inside the reaction chamber H, there is a flat plate-shaped lower part on the lower side! [12 and a flat upper electrode parallel to the lower electrode sphere are disposed on the upper side, and the lower 'NtfMu
A high-frequency power source 14 for applying high-frequency power to the reaction chamber U is provided, and a gas supply port for supplying the reaction gas is provided on one side of the reaction chamber U, and an exhaust means (not shown) is provided on the side opposite to the gas supply port. ), and a magnet d is disposed above the upper part 11E to generate a magnetic field perpendicular to the electric field and increase the plasma density, thereby configuring a magnetron RIE device. There is. A ring ring made of an insulating material such as aluminum oxide (AbOs) and having a height of 2 to 20 mm is disposed around the lower base of the Magnelon RIE apparatus. Lower part [[1
An object to be etched 19 is placed on top of the etching plate 2.

The following is an Al-5i test using the apparatus shown in Figure 1.
-Explaining the etching process of Cu alloy〇The object to be etched 19 is a thermal oxide film with a thickness of 0.5 μm formed on a silicon wafer with a diameter of 150, and a thermal oxide film with a thickness of 1 μm on top of the silicon wafer.
An AI-Si-Cu alloy is sputter-deposited on the AJ-5f-Cu alloy film, and a thickness of 1. l
TM photoresist 0FPR-5000 (manufactured by Tokyo Oyoyo Kako ■) was coated, exposed and developed to form a mask pattern, and prepared. This object to be etched 19 was placed on the upper surface of the lower frame Wiν, and a mixed gas of chlorine and boron trichloride was introduced as a reaction gas at a pressure of I The height of the ring slide was changed and the AI-8i
-Etching rate (A/min) and AI of Cu alloy
Figure 2 shows the relationship between -5i -Cu and resist, and Figure 3 shows the relationship with vct (-v) and surface temperature (1), as well as undercuts and copper residue. The situation is shown in Table 1.

Figure 2 (As is clear from the results shown, as the height of the ring height increases, the etching rate of the AI-S i -Cu alloy decreases slightly, but the etching rate of the Al-3i-Cu alloy
/Resist increases significantly. This is thought to be because, as shown in Figure 8, Vdc decreases in proportion to the height of the ring, and the surface temperature of the resist decreases, resulting in a rapid decrease in the etching rate of the resist. It will be done. However, if the ring height is 25 mm or more, as shown in Table 1, undercuts occur in the etched shape and copper residue tends to be formed on the etched surface, which is undesirable. If is less than l mx, AI 5t-Cu/v cyst is 2.2/
It is not preferable that the height is lower than 1, and in particular, when the ring height is 0 (no ring), it is about 1.7/1, which is inappropriate for mass production.

As described above, by providing a ring slide of Al2O5 around the lower electrode 4 of the magnetron RIE device, it is possible to improve the effectiveness of the magnetron RIE device. )
, AI-8i-Cu/resist can be increased, especially in the height range of 2 to 20 WJL.
- While keeping the Si-Cu/resist in a state of 8i1 or higher, if an undercut occurs in the etched shape, copper residue may be formed on the etched surface (A
Etching of l-Si-Cu alloys can be performed.

In addition, in the above examples, a mixed gas of chlorine and boron trichloride was used as one reaction gas, but other chlorine-based gases were used.
Any material that can etch the I-Si-Cu alloy may be used.

In order to achieve the above effects of the invention, a ring made of an insulating material is provided around the lower electrode of a magnetron RIE device, and a chlorine-based gas is used as a reaction gas to perform dry etching of the AI-5i-Cu alloy. The method of the present invention reduces the cathode drop voltage (Vdc) and lowers the wafer surface temperature during etching, resulting in a reduction in etching of Al-Si-Cu/resist or Al-5i-Cu alloy and resist. The speed ratio increases significantly, greatly improving mass productivity.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of the apparatus used in the dry etching method of AI-3i-Cu alloy of the present invention.
The figure shows the ring height, etching rate of Al-Si-Cu alloy, and AI-Si-Cu/Al-Si-Cu alloy in the same example.
FIG. 8 is a diagram showing the relationship between the ring height and cathode drop voltage and wafer surface temperature in the same embodiment. FIG. 4 is a schematic cross-sectional view of a conventional device. ■...Reaction chamber, chamber...lower electrode, port...upper electrode, 14...high frequency power supply, b...gas supply port, υ...
- Magnet, quick ring, 19... object to be etched.

Claims (1)

[Claims] 1. Applying high frequency power to a pair of parallel upper and lower plate electrodes,
A ring made of an insulating material is provided around the lower electrode of a magnetron reactive ion etching device having means for generating a diverging magnetic field perpendicular to the generated electric field,
And by forming a chlorine-based gas plasma, Al-Si-Cu
Al-Si-C characterized by etching alloy
Dry etching method for u-alloy. 2. The height of the ring provided around the lower electrode is 2 mm or more.
A method for dry etching an Al-Si-Cu alloy according to claim 1, wherein the thickness is 20 mm. 3. The method for dry etching an Al--Si--Cu alloy according to claim 1, wherein the insulating material forming the ring provided around the lower electrode is Al_2O_3.