JPH07161687A - Dry etching method and equipment - Google Patents

Abstract

PURPOSE:To make possible precise dry etching of Cu or Cu alloy by introducing gas of aluminum halide, gas of halide except halogen gas and/or aluminum halide, and gas capable of turning to neutral ligand into a vacuum equipment, and generating plasma. CONSTITUTION:A Cu film is formed on the surface of an Si substrate S1 further a wiring patter is drawn by using resist on it, and then the substrate S1 is carried in a vessel 1 and mounted on an electrode 2. From gas supply part 5, Cl2 gas and NH3 gas capable of turning to neutral ligand are introduced into a vessel 1, and BCl3 gas for accelerating etching is introduced. By heating the inside of a thermostatic chamber 43, AlCl3 431 evaporated and introduced into the vessel 1. The mixed gas is turned into plasma, and the Cu film on the substrate S1 surface is etched. Thereby Cu or Cu alloy can be dry-etched with high precision.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching process in which an etching gas is turned into plasma by applying electric power and an object to be processed is etched under the plasma to form wirings and electrodes on a substrate. Formed copper (C
The present invention relates to a method and apparatus for dry etching a film of u) or Cu alloy.

[0002]

2. Description of the Related Art A dry etching process in which an etching gas is turned into plasma by applying electric power and an object to be processed is etched under the plasma is used to manufacture various devices such as thin film transistors, LSIs, and solar cells using semiconductors. In this case, it is widely used for etching a metal film formed on a substrate while leaving a wiring pattern, an electrode pattern, etc., and for etching a semiconductor film formed on a substrate while leaving a predetermined pattern. .

The dry etching process is performed using a parallel plate type etching apparatus used for reactive ion etching (RIE) shown in FIG. 2, for example. This etching apparatus includes a vacuum container 1 and an electrode 2 which also serves as a substrate holder on which a substrate S2 on which a film to be etched is formed is installed. The electrode 2 is used as a power application electrode for applying high frequency power or direct current power to the etching gas introduced into the container 1 to turn it into plasma. In the illustrated example, the electrode 2 is connected to the high frequency power supply 22 via the matching box 21. It is connected.

The vacuum container 1 is further connected to an exhaust device 7 connected to an exhaust pump 72 via a valve 71 and a gas supply unit 6 connected to the vacuum container 1. The gas supply unit 6 includes one or more mass flow controllers 611, 612, ... And open / close valves 621, 622.
The gas sources 631, 632, ... Supplying a required amount of etching gas via.

According to this etching apparatus, the substrate S2 to be etched is placed on the high frequency electrode 2 in the container 1,
The inside of the container 1 is set to a predetermined vacuum degree by the operation of the exhaust device 7,
An etching gas is introduced from the gas supply unit 6. Further, high-frequency power is applied to the electrode 2 from the high-frequency power source 22, the gas introduced thereby is turned into plasma, and the film on the substrate S2 is etched under this plasma.
The temperature of the electrode 2 may be controlled by a temperature control device such as the water cooling device 20 if necessary.

Further, in RIE using the above etching apparatus, when the etching target is a substrate coated with a Cu or Cu alloy film for forming wiring, electrodes, etc., Cu or Cu alloy is difficult to be etched, and particularly, When using a gas containing halogen as an etching gas,
Cu reacts with halogen to form copper halide, and often remains as an etching residue because the vapor pressure of the compound is low.

According to Japanese Patent Laid-Open No. 4-180580,
By using a mixed gas consisting of an aluminum halide gas and a halogen gas or a halide gas as an etching gas, a complex composed of copper / aluminum / halogen is generated, and the vapor pressure of the compound is high. It is disclosed that the etching residue is small.

Further, according to JP-A-4-173988, copper / halogen is prepared by using a mixed gas consisting of a gas of a substance capable of becoming a neutral ligand and a halogen gas or a halide gas as an etching gas. -It is disclosed that a complex composed of a neutral ligand is generated and the vapor pressure of the compound is high, so that the etching residue is small.

[0009]

However, even with the above method, a slight amount of etching residue remains, which limits the dimensional accuracy of the electrodes and wirings to be formed and hinders the miniaturization of the electrodes and wirings. Therefore, it is an object of the present invention to provide a dry etching method and apparatus capable of dry etching Cu or Cu alloy with extremely high precision.

[0010]

According to the method of the present invention for solving the above-mentioned problems, at least an aluminum halide gas, a halogen gas or (and) a halide gas other than aluminum halide, and neutral coordination are used. A gas of a substance that can serve as a child is introduced into a vacuum device, and the mixed gas is turned into plasma by applying power under a predetermined vacuum state. Under this plasma, Cu or C is previously placed in the vacuum device.
The u alloy is characterized by being dry-etched.

Further, the apparatus of the present invention for solving the above-mentioned problems includes a vacuum device which can be brought into a predetermined vacuum state by exhaust means, and the vacuum device has at least a solid aluminum halide gas to an aluminum halide gas. A means for introducing the gas, which includes means for generating a gas, a means for introducing a halogen gas or a halide gas other than aluminum halide, and a means for introducing a gas of a substance that can be a neutral ligand are connected. At the same time, an electrode serving also as a support holder for the etching object, and an electric power applying means connected to the electrode also serving as the support holder for plasmaizing the gas introduced into the vacuum device are characterized by being provided. To do.

In the above method and apparatus, the aluminum halide is aluminum chloride (AlCl ₃ ),
Aluminum bromide (AlBr ₃ ), aluminum iodide (AlI ₃ ) and the like can be mentioned, and one or more of these are used. As the halogen gas, fluorine (F ₂ ) gas, chlorine (Cl ₂ ) gas, bromine (Br ₂ )
Gas, iodine (I ₂ ) gas and the like can be mentioned, and one or more of these can be used.

Further, as halides other than aluminum halide, hydrogen fluoride (FH), hydrochloric acid (HC
l), hydrogen bromide (HBr), hydrogen halide such as hydrogen iodide (HI), carbon tetrafluoride (CF ₄ ), fluoroform (CHF ₃ ), monofluoromethane (CH ₃ F), tetrachloride Methane (CCl ₄ ), chloroform (CHCl ₃ ), methane dichloride (CH ₂ Cl ₂ ), methane monochloride (CH ₃ C
l), bromoform (CHBr ₃ ), methane dibromide (C
H ₂ I ₂ ), compounds in which hydrocarbon hydrogen such as methane monoiodide (CH ₃ I) is replaced with halogen, boron trifluoride (BF ₃ ), boron trichloride (BCl ₃ ), boron tribromide ( It is possible to use boron halides such as BBr ₃ ), and one or more of them can be used.

When one kind of compound is used for each of the above-mentioned aluminum halide, halogen gas, and halides other than aluminum halide, the kinds of halogen may be the same or different.
Alternatively, they may be partially different. Examples of the substance that can be a neutral ligand include substances that can be monodentate or polydentate ligands such as ammonia (NH ₃ ) and nitric oxide (NO).

Further, in the above method, in addition to the etching gas, a gas such as an inert gas which promotes etching may be added within a range where the intended effect is obtained. Prior to etching, an inert gas such as helium (He), argon (Ar), neon (Ne), or krypton (Kr) is introduced into the vacuum device, and plasma is generated by applying power to the gas under a predetermined vacuum state. Then, the surface of Cu or Cu alloy, which is an etching target, may be cleaned under this plasma.

Further, in the above apparatus, in addition to the means for introducing the etching gas, the vacuum apparatus introduces a gas for promoting etching such as an inert gas within a range in which a desired effect is obtained. May have
Further, the vacuum device may have a means for introducing an inert gas such as He, Ar, Ne, Kr or the like for cleaning the surface of the etching target.

[0017]

According to the method and apparatus of the present invention, an aluminum halide gas as an etching gas, a halogen gas, and / or an oxygen gas are contained in a vacuum apparatus having a predetermined vacuum degree.
Gas of halide other than aluminum halide,
A gas that is a substance that can serve as a neutral ligand is introduced, and direct-current or high-frequency power is applied to the gas to turn the etching gas into plasma. The plasma reacts with copper contained in the etching target to first generate copper chloride, and further a complex composed of copper, aluminum, chlorine, and a neutral ligand.

The complex as an etching product has a high vapor pressure and is easily desorbed from the surface of the object to be etched into the gas phase.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a parallel plate type etching apparatus used for RIE which is one embodiment of the apparatus of the present invention. This apparatus includes an etching gas supply unit 3 in place of the etching gas supply unit 6 in the conventional etching apparatus shown in FIG. 2, and the gas supply unit 3 includes an aluminum halide gas supply unit 4 and an aluminum halide gas supply unit 4. It is composed of an etching gas supply unit 5 other than an aluminum halide gas.

Aluminum halide gas supply section 4
Includes a constant temperature bath 43 which is connected by piping via a mass flow controller 41 and an opening / closing valve 42. Constant temperature bath 43
A solid aluminum halide 431 and a heater 432 are arranged inside, and a temperature control device 433 including a power supply circuit and a temperature controller is connected to the heater 432. The control of the supply amount of the aluminum halide gas into the container 1 is performed by temperature control by the temperature control device 433 and the heater 432, the mass flow controller 41, and the on-off valve 4.
It can be performed by controlling the flow rate of the gas according to 2. In addition, you may heat all or one part of the controller 41, the valve 42, and piping as needed.

The gas supply section 5 for the gas other than aluminum halide has two or more mass flow controllers 511,
512, 513, ... and on-off valves 521, 522, 52
Gas sources 531, 532, 53 pipe-connected through 3
3, and at least one kind of halogen gas or (and) at least one kind of halide gas other than aluminum halide, and at least one kind of gas of a substance that can be a neutral ligand. Can be supplied. In this example, an inert gas for cleaning the substrate prior to etching and a gas for promoting etching can also be introduced. Further, in this example, each gas source of the gas supply unit 5 is connected to the vacuum container 1 using a common pipe, but may be connected to each other using different pipes.

According to the dry etching apparatus of the present invention described above, the method of the present invention is carried out as follows. The substrate S1 to be etched is carried into the vacuum container 1 and placed on the high-frequency electrode 2 which also serves as a substrate holder, and the inside of the container 1 is brought to a predetermined vacuum degree by the operation of the exhaust device 7. Further, the solid aluminum halide 431 is heated by raising the temperature in the constant temperature bath 43 by the heater 432,
Aluminum halide gas is generated and stored in the constant temperature bath 43. Next, an etching gas other than an aluminum halide gas is introduced from the gas supply unit 5 into the container 1, an aluminum halide gas is introduced from the gas supply unit 4, and a high frequency power is applied from the high frequency power supply 22 to the electrode 2. The gas introduced thereby is turned into plasma, and the film on the substrate S1 is etched under this plasma.

Next, a specific example in which the Cu film formed on the silicon (Si) substrate is dry-etched using the etching apparatus shown in FIG. 1 will be described. Example 1 A Cu film with a thickness of 12000Å was formed on the surface, and a wiring pattern was drawn on it with a resist.
A Si substrate S1 having a thickness of m and a thickness of 0.65 mm was loaded into the container 1 and placed on the electrode 2.

First, the inside of the container 1 is evacuated to a degree of vacuum of 1 × 10 ⁻³ Torr, and then Kr gas having a purity of 5N (99.999%) for pretreatment for cleaning the substrate is supplied from the gas supply unit 5. Flow rate of 90 sccm until the inside of 1 reaches 4 × 10 ^-2 Torr
In addition, the high frequency power of 13.56 MHz is applied to the electrode 2 at a power of 500 W to generate Kr gas into plasma, and the inorganic oxides and organic substances adhering to the surface of the substrate S1 are removed under the plasma. It was

Next, the inside of the container 1 is 1.5 × 10 ⁻¹ Torr.
After setting the degree of vacuum to Cl ₂ gas and N ₂ from the gas supply unit 5.
H ₃ gas was introduced at a flow rate of 20 sccm, and BCl ₃ gas was introduced at a flow rate of 25 sccm as a gas for promoting etching. On the other hand, 16
AlCl ₃ 431 was evaporated by heating at 0 ° C. and introduced into the container 1 at a flow rate of 100 sccm. At the same time, high frequency power of 13.56 MHz was applied to the electrode 2 at a power of 275 W for 550 seconds to plasmaize the above gas to etch the Cu film on the surface of the substrate S1.

At this time, it is considered that a two-step reaction represented by the following equation proceeds on the surface of the substrate S1 to form a Cu complex. _{Cu + x / 2Cl 2 → CuClx} CuCl x + yNH 3 + zAlCl 3 → _{[CuAlz (NH 3) y Cl x} + 3z ] Further, Cu film having a thickness of 12000Å took to be etched time is 450Sec, etching residue Everything could be accurately etched according to the wiring pattern. Example 2 In Example 1, NH ₃ of the etching gas was used.
Etching was performed in the same manner as in Example 1 except that NO gas was used instead of gas and other conditions were used.

At this time, it is considered that a two-step reaction represented by the following equation proceeds on the surface of the substrate S1 to form a Cu complex. Cu + x / 2Cl ₂ → CuClx CuCl _x + yNO + zAlCl ₃ → [CuAlz (NO) _y Cl _{x + 3z} ] Further, the time required for etching the Cu film having a thickness of 12000Å is 800 sec, and no etching residue remains. Highly accurate etching can be performed according to the wiring pattern. Example 3 In Example 1, BCl ₃ gas was used instead of Cl ₂ gas in the etching gas, and etching was performed in the same manner as in Example 1 under other conditions. However, in Example 1, BCl ₃ gas was used as a gas for promoting etching, but in this example, BCl ₃ gas was used as an etching promoting gas in addition to the etching gas.
No Cl ₃ gas was used. At this time, the substrate S
It is considered that the two-stage reaction shown in the following formula proceeds on one surface to form a Cu complex.

[0028] _{Cu + x / 3Cl 3 → CuClx} CuCl x + yNH 3 + zAlCl 3 → _{[CuAlz (NH 3) y Cl x} + 3z ] Further, a 24min time is that required for the Cu film having a thickness of 12000Å is etched, In addition, no etching residue remained, and accurate etching could be performed according to the wiring pattern. Example 4 In Example 1, etching was carried out in the same manner as in Example 1 except that CCl ₄ gas was used instead of Cl ₂ gas in the etching gas.

At this time, it is considered that a two-step reaction represented by the following equation proceeds on the surface of the substrate S1 to form a Cu complex. _{Cu + x / 4CCl 4 → CuClx} CuCl x + yNH 3 + zAlCl 3 → _{[CuAlz (NH 3) y Cl x} + 3z ] Further, Cu film having a thickness of 12000Å took to be etching time is 500 sec, the etching residue Everything could be accurately etched according to the wiring pattern.

Further, as Comparative Example 1, Cl ₂ gas (20 sccm) and AlCl ₃ (100
sccm) gas was used and etching was performed in the same manner as in Example 1 under other conditions. At this time, it is considered that the two-stage reaction represented by the following formula proceeds on the surface of the substrate S1 to form a Cu complex.

[0031] _{Cu + x / 2Cl 2 → CuClx} CuCl x + yAlCl 3 → [CuAl _y Cl _{x + 3y]} The time taken to Cu film having a thickness of 12000Å is etched but was 400 sec, a slight residue Remainingly, the etching accuracy was slightly inferior to the etchings of Examples 1, 2, 3 and 4.

As Comparative Example 2, C was used as an etching gas.
l₂Gas (20 sccm) and NH ₃(20 sccm)
Etching is performed in the same manner as in Example 1 except that gas is used.
I went At this time, on the surface of the substrate S1, two steps shown by the following equation
It is considered that the reaction of the floor progresses and a Cu complex is generated.
available.

Cu + x / 2Cl ₂ → CuClx CuCl _x + yNH ₃ → [Cu (NH ₃ ) _y Cl _x ] Further, the time required for etching the Cu film having a thickness of 12000 Å was 450 sec, but a little The residue remained, and the etching accuracy was slightly inferior to the etchings of Examples 1, 2, 3 and 4.

As a result of the above, it is understood that the etchings of Examples 1, 2, 3 and 4 were more accurate than the etchings of Comparative Examples 1 and 2 with less etching residue. Compared with the complex composed of copper / aluminum / halogen and the complex composed of copper / aluminum / neutral ligand, the vapor pressure of the complex composed of copper / aluminum / halogen / neutral ligand is It is considered to be high and more easily desorbed from the solid phase.

Although the dry etching by RIE has been described in the present embodiment, the present invention is not limited to this, and dry etching by plasmaizing an etching gas utilizing electromagnetic resonance (ECR), photoexcitation, or the like is also performed. You can

[0036]

As described above, according to the present invention, C
It is possible to provide a dry etching method and apparatus that can dry-etch u or Cu alloy with extremely high accuracy.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a dry etching apparatus that is an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an example of a conventional dry etching apparatus.

[Explanation of symbols]

1 Vacuum Container 2 Substrate Holder and High Frequency Electrode 20 Water Cooling Device 21 Matching Box 22 High Frequency Power Supply 3 Supply Part for Etching Gas and Pretreatment Gas 4 Supply Part for Aluminum Chloride (AlCl ₃ ) Gas 43 Constant Temperature Tank 431 Solid AlCl ₃ 432 Heater 433 Temperature controller 5 Supplying parts for etching gas and pretreatment gas other than AlCl ₃ 511, 512, 513, ... 41 Mass flow controller 521, 522, 523, ... 42 Open / close valve 531, 532 533 gas source 7 exhaust device 71 valve 72 exhaust pump S1, S2 substrate

Claims (2)

[Claims] 1. At least a gas of aluminum halide, a gas of halogen gas or (and) a halide other than aluminum halide, and a gas of a substance which can be a neutral ligand are introduced into a vacuum device, A dry etching method in which this mixed gas is turned into plasma by applying electric power in a predetermined vacuum state, and copper or a copper alloy previously placed in the vacuum apparatus is dry-etched under the plasma. 2. A vacuum device which can be brought into a predetermined vacuum state by an exhaust means, and at least the vacuum device,
Means for introducing a gas of aluminum halide from solid aluminum halide, and means for introducing the gas,
An electrode that connects a means for introducing a halogen gas or (and) a gas for a halide other than aluminum halide and a means for introducing a gas for a substance that can be a neutral ligand, and that also serves as a support holder for the etching target, A dry etching apparatus, comprising: an electric power application unit connected to an electrode that also serves as the support holder to turn a gas introduced into the vacuum apparatus into plasma.