JPH028380A - Method and apparatus for dry etching - Google Patents

Abstract

PURPOSE:To prevent the corrosion of an Al fine pattern by continuously carrying out etching treatment, photoresist peeling treatment, and the desorption of residual etching gas without exposure to the air in the course of the above treatments at the time of forming fine pattern of Al, etc., by a dry etching method. CONSTITUTION:A cassette 8a in which a substrate 5 equipped with Al foil and photoresist for forming fine wiring is placed is introduced into a spare vacuum chamber 9a, and, after the inside of this spare vacuum chamber 9a is evacuated by means of an exhaust system 90a, a gate valve 10a is opened and the above substrate 5 is introduced into a vacuum substrate conveyance chamber 4, and this substrate 5 is moved onto a substrate-holding stage 7a and pushed up to the bottom of a dry etching chamber 1. A chlorine-type reactant gas is introduced through a pipe 12, and the Al on the substrate 5 surface is etched according to a photoresist pattern. Subsequently, the substrate 5 is moved through the same vacuum conveyance chamber 4 and subjected to the peeling off of the photoresist film from the substrate 5 and the removal of the adhering reactive gas in a resist peeling chamber 2 and a reactant gas desorption chamber 3, respectively, and then, this substrate 5 is taken out via a second spare vacuum chamber 9b into the air. Since all the operations are carried out in the vacunm conveyance chamber 4, the corrosion of an Al wirtng cansed by a liquid resulting from the reactlon of residual chlorinated gas with the moisture in the air can be prevented.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a novel dry etching method particularly suitable for forming fine patterns of aluminum wiring or metal wiring during the manufacture of semiconductor integrated circuits, etc. Regarding the device.

(Prior art) Conventionally, an aluminum film was applied on a substrate to be processed (hereinafter referred to as a substrate).
In the case of dry etching to create mini-RAM wiring patterns or metal wiring patterns (hereinafter referred to as aluminum wiring), chlorine-based gases such as chlorine, tungsten trichloride, and silicon tetrachloride are often used as the etching gas. However, there is a phenomenon in which chlorine compounds are adsorbed on the side walls of aluminum wiring and on the resist surface after etching.

If the substrate is taken out into the atmosphere in this state (in this case, the chlorine compound reacts with moisture in the atmosphere, becomes ionized, and corrodes the aluminum).

In particular, the wiring is in contact with the A9 alloy film layer =-(TTi, W
When having an edible barrier/layer of dissimilar metals such as A u
The battery effect occurs due to the difference in hydrogen overvoltage between these dissimilar metals, making it easier for corrosion to progress.

Conventionally, methods for preventing this type of corrosion include, for example, after etching: ■ replacing the gas in the dry etching chamber with a Freon-based gas and subjecting the substrate to Freon gas plasma treatment, or ■ introducing oxygen gas into the dry etching chamber. The adsorbed chlorine compounds are removed by introducing the photoresist into the substrate and plasma stripping the photoresist, ■ quickly taking it out into the atmosphere and heating each substrate with nitrogen gas, and ■ washing the substrate with water through a water bath. A method was used to remove the . Furthermore, as another corrosion prevention method, there is also a method in which the substrate is plasma treated using a gas that easily causes plasma polymerization, such as CFIF 3, and the etched surface is coated with a thin "polymer film" to prevent corrosion. It was getting worse.

(Problems to be Solved by the Invention) However, in the above conventional method, the Al1 alloy film, especially the
(1-ct1 alloy film, barrier layer containing Ti and W and A
Etching a film having a structure in which α alloy films are laminated has the drawback that the corrosion prevention effect is not sufficient.

For example, the results of a surface analysis revealed that Freon gas plasma treatment cannot reduce the concentration of chlorine compounds adsorbed on the surface to O.

In addition, when the resist is removed using oxygen gas branuma, the amount of chlorine adsorbed on the etched surface appears to be very small, but it corrodes within several tens of minutes to several hours after the substrate is taken out into the atmosphere. There have been cases where this has occurred.

Furthermore, regarding the case where substrates are quickly taken out of the etching chamber and heated or washed with water, all conventional equipment used for this type of processing is an in-line process that heats or washes and dries the substrates one by one. Perhaps due to the nature of the equipment, the processing time for one board is only on the order of a few minutes at most. In some cases, washing with water may actually induce and increase corrosion.

Moreover, during the short time that the etched substrate is transported to the heating furnace or the 1' washing tank in the atmosphere, corrosion occurs, especially in the Al-S 1-Cu/TiW double film as mentioned above. It often occurred.

On the other hand, the method of coating the surface of the aluminum wiring and photoresist with a thin plasma polymerized film using gas plasma such as CHF 3 to prevent corrosion is a very effective method compared to other methods. However, since the chlorine compounds are carried to the next process while being adsorbed, corrosion may occur when the plasma polymerized film is peeled off in the next process, so this method was not necessarily effective.

(Object of the Invention) The object of the present invention is to provide a tri-etching method and apparatus thereof, which eliminate the drawbacks of the above-mentioned conventional techniques and enable complete corrosion prevention treatment of fine wiring patterns such as aluminum wiring during the manufacture of large-scale integrated circuits. The purpose is to provide.

(Means for Solving the Problems) In order to achieve the above object, the present invention uses a reactive gas containing chlorine atoms as a main component, and uses photolithography as a mask to remove aluminum on a substrate to be etched. Or a dry etching device for etching aluminum alloy film? Here, following the etching treatment of the aluminum or aluminum alloy film, a resist peeling treatment is performed to peel off the photoresist without exposing the substrate to the atmosphere, and further, following the peeling treatment, the substrate is removed. A dry etching method is adopted in which chlorine removal treatment is performed to remove residual chlorine compounds on the substrate without exposing it to the atmosphere.

The method for dechlorination treatment is to remove the substrate in vacuum for 10 minutes.
There is a method of heating the substrate to 0° C. or higher, and a method of subjecting the substrate to plasma treatment using a gas containing fluorine atoms. The equipment that uses this method includes a dry etching chamber for etching the aluminum or aluminum alloy film, a resist stripping chamber for stripping off the photoresist, and a chlorine removal chamber for stripping off the chlorine compounds remaining on the substrate. A dry etching device in which two adjacent chambers, a separation chamber and a chamber 03, are connected by a substrate transfer chamber that transfers a substrate in vacuum, and a dry etching chamber that etches an aluminum or aluminum alloy film. All three chambers, a resist stripping chamber for stripping off the photoresist and a chlorine desorption chamber for stripping off chlorine-based compounds remaining on the substrate during the stripping process, are connected to a single chamber in which the substrate is transported in vacuum. There is a dry etching device connected to the substrate transfer chamber.

(Function) In the method and apparatus of the present invention having the above configuration,
After the aluminum wiring or metal wiring pattern on the substrate to be etched is etched with chlorine-based gas using a photoresist as a mask, the photoresist is removed without breaking the vacuum. can be almost removed when the photoresist is peeled off. Furthermore, after the photoresist is removed, it is heated without breaking the vacuum or plasma treated with a gas containing fluorine, so that the fluorine enters the interface between the aluminum surface and the photoresist, and during the photoresist removal. Since reaction products containing trace amounts of residual chlorine appearing on the aluminum surface can be removed, corrosion of aluminum wiring or metal wiring patterns can be completely suppressed.

(Embodiment) FIG. 1 shows a schematic sectional view of a dry etching apparatus according to an embodiment of the method of the present invention, in which a dry etching chamber 1 for an aluminum film, a resist! ! II. The pressure chambers of the chamber 2 and the chlorine desorption chamber 3 for desorbing residual trace chlorine compounds are installed so as to open to the −L section of the substrate transfer chamber 4 that is common to the pressure chambers. .

Immediately below the pressure chamber inside the substrate transfer chamber 4 are stages "74, 7)) and 7C that hold the substrates 5, respectively, and substrate transfer mechanisms (arrows 804, 80b, 80C).

80d) is installed.

On the other hand, on both sides of this substrate transfer chamber 40, there are a vacuum preliminary chamber 9a in which a cassette 8a containing unprocessed substrates is set, and a vacuum preliminary chamber 9b in which a cassette 8a containing processed substrates is set. Valves 10a and 10b
connected via.

To describe the operation of this device, first, the gate valves 10a and 10b are separated, and in the current state in which the stages 74, 7b, and 7C are all lowered, the inside of the substrate transfer chamber 4 is pumped with a turbo molecular pump and a cryopa bomb (not shown). Evacuate to high vacuum using

Next, the valve 10a is closed and the lid 11a is opened to open the vacuum preliminary chamber 9a to the atmosphere, and the cassette 8a containing the unprocessed substrate 8a is set in the vacuum preliminary chamber. Next, the lid]
, 1a is closed, and the vacuum preliminary chamber 8a is evacuated using the exhaust system 90a.

After the vacuum preliminary chamber 8a reaches a predetermined degree of vacuum, the valve 1
0a is opened, and the substrate 5 in the cassette 8a is transferred and placed on the stage 7a in a high vacuum.

Next, the drive mechanism shown schematically by the arrow? Stage 7a at 2a
by raising the flange surface 10 of the dry etching chamber 1.
The edge surface 70a of the stage 7a is hermetically pressed against the substrate transfer chamber 4 and the tri-etching chamber 1. Then, a reactive gas containing chlorine atoms is introduced into the dry etching chamber 1 from the gas introduction pipe 12 (while exhausting the gas with an exhaust system (not shown)) to maintain the interior of the dry etching chamber 1 at a predetermined pressure.

When high-frequency power is applied from an external electric current 71 to the stage 7aζ, reactive plasma is generated in the dry etching chamber 1, and the aluminum film is dry etched by reactive ion etching (RIE). After the etching process of the aluminum wiring is completed, the introduction of reactive gas is stopped, the trial etching chamber 1 is evacuated, and the stage 7a is lowered by driving with the drive mechanism 72a, and the dry etching chamber 1 becomes a substrate transfer chamber. It is opened and returns to the state shown in FIG.

Next, the substrate transfer mechanism 80b provided in the substrate transfer chamber 4
Then, the substrate on the stage 7a is transferred and placed on the stage 7b. Then, the stage 7b is raised by the τ drive mechanism 72b, and the edge surface 701) of the stage 71) is brought into airtight pressure contact with the flange surface 200 of the resist stripping chamber 2. A gas containing oxygen is introduced from the introduction tube 22 (while exhausting the plasma), and a high frequency voltage is applied between high frequency electrodes 25 and 26 provided around the plasma generation chamber 24 made of quartz. As a result, a large amount of oxygen radicals are generated in the plasma generation chamber, and the photoresist film on the substrate is peeled off by these oxygen radicals. During this peeling, the peeling speed can be increased by heating the substrate with a heater (not shown) installed in the stage 7b.

After the photoresist is removed, the stage 7b is lowered to open the resist removal chamber 2 to the substrate transfer chamber 4, and the substrate is transferred and placed on the stage 7C by the transfer mechanism 80c provided in the substrate transfer chamber 4. do.

The stage 7c is raised by the drive mechanism 72c and the edge surface 70c of the stage 7C is placed on the flange surface 300 of the chlorination removal chamber 3.
A gas containing fluorine atoms such as CF4 is introduced from the gas introduction pipe 32, and a high frequency power source 31 is connected to the counter electrode 39.
Plasma is generated by applying a high-frequency voltage to the substrate, and the substrate is plasma-treated, thereby desorbing chlorine.

Thereafter, the stage 7C is lowered to return to the state shown in FIG. 1, and the substrate is transported and housed in the cassette 8b in the vacuum preliminary chamber 9b, thus completing the series of processes. When the cassette 8b is full, the valve 10b is closed, the door 9b is opened, and the substrate is taken out into the atmosphere for the first time.

When a substrate is being processed in one processing chamber (for example, a resist stripping chamber), another processing is performed on another substrate in another processing chamber (for example, a dry etching chamber). Productivity can be improved.

When the substrate is processed without being exposed to the atmosphere as described above, most of the chlorine-based compounds adsorbed on the side walls of the aluminum wiring on the substrate are removed when the photoresist is removed after etching. Since the substrate is then treated with Freon plasma, the chlorine compounds that have penetrated deep into the interface between the photoresist and the aluminum film, as well as trace amounts of chlorine compounds that could not be removed by oxygen plasma treatment, are completely removed by the Freon gas. With this substitution, corrosion of aluminum wiring is completely suppressed.

FIG. 2 shows a schematic layout of each chamber of a dry etching apparatus according to another embodiment of the present invention. The dry etching chamber 1 and the resist stripping chamber 2 are connected to each other by a substrate transfer chamber 4a, and the resist stripping chamber 2 and the chlorination removal chamber 3 are connected to each other by a substrate transfer chamber 4a.
1), and all the chambers are connected in series together with the vacuum preliminary chambers 94 and 9b. The device is somewhat more complex than the one shown in FIG. 1 and is economically disadvantageous.

In addition, although the method for desorbing trace amounts of chlorine compounds is shown above as plasma treatment using fluorine gas, it is also possible to use a heater or an infrared lamp in the plasma treatment chamber 3 without using fluorine gas. A treatment method in which the substrate is prepared and simply heated to 100° C. or higher is also effective in eliminating chlorine.

Further, the chlorination desorption chamber does not have to be a parallel plate type plasma processing apparatus, but may be a processing chamber having a structure in which a plasma generation chamber is separately provided and radicals are transported from there, as in the resist stripping chamber 2.

Furthermore, although the above description has been made using an example of an apparatus in which substrates are processed one by one and each process is performed in each independent chamber, the present invention is not limited to this. Even if it is a batch type processing apparatus, which has only one processing chamber and performs the processing of the present invention by successively replacing the gas, the effects can be sufficiently improved. In this case, a substrate transfer chamber is not required.

(Effects of the Invention) By using the method and apparatus of the present invention, it is possible to effectively prevent corrosion in etching aluminum and aluminum alloy films.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an apparatus according to an embodiment of the present invention. FIG. 2 is a layout diagram of each chamber of the apparatus according to another embodiment. DESCRIPTION OF SYMBOLS 1... Dry etching chamber, 2... Resist stripping chamber, 3-- Chlorine removal chamber, 4.44, 4b... Substrate transfer chamber, 5... Substrate.

Claims (1)

[Scope of Claims] (1) A dry etching method in which an aluminum or aluminum alloy film on a substrate to be etched is etched using a reactive gas containing chlorine atoms as a main component and using a photoresist as a mask. Following the etching treatment of the aluminum or aluminum alloy film, a resist stripping treatment is performed to strip the photoresist without exposing the substrate to the atmosphere, and further, following the stripping treatment, without exposing the substrate to the atmosphere. . A dry etching method comprising performing a chlorine desorption treatment to desorb residual chlorine compounds on the substrate. (2) The method of chlorine desorption treatment is performed by removing the substrate in vacuum.
The dry etching method according to claim 1, characterized in that the dry etching method is a method of heating to 00° C. or higher. (3) The dry etching method according to claim 1, wherein the method for dechlorination treatment involves subjecting the substrate to plasma treatment using a gas containing fluorine atoms. (4) The gas containing fluorine atoms used in the plasma treatment is CF_4, CHF_3, SF_6, NF
4. The dry etching method according to claim 3, wherein the gas contains any one of _2, C_2F_6. (5) The dry etching method according to claim 4, wherein the gas containing fluorine atoms used in the plasma treatment is a mixed gas containing any one of O_2, N_2, Ar, and He. (6) A dry etching chamber where the aluminum or aluminum alloy film on the substrate to be etched is etched using a reactive gas mainly containing gas containing chlorine atoms using a photoresist as a mask, and a resist stripping chamber where the photoresist is stripped off. and a chlorine desorption chamber for desorbing chlorine-based compounds remaining on the substrate, two adjacent chambers are provided.
A dry etching apparatus characterized in that each of the dry etching apparatuses is connected by a substrate transfer chamber that transfers the substrate in a vacuum. (7) A dry etching chamber for etching the aluminum or aluminum alloy film on the substrate to be etched with a reactive gas mainly containing gas containing chlorine atoms using a photoresist as a mask, and a resist stripping chamber for stripping off the photoresist. and a chlorine desorption chamber that desorbs chlorine-based compounds remaining on the substrate during the peeling process, all of which are connected to a single substrate transfer chamber that transfers the substrate in vacuum. Dry etching equipment featuring: