JPH0212914A - Etching device - Google Patents

Abstract

PURPOSE:To prevent corrosion of a metal film on a wafer due to a residual reactive gas by constructing a vacuum preliminary room into which a processed wafer is inserted, a coarse exhaust pump for exhausting this vacuum preliminary room at about atmospheric pressure, and gas introducing means for introducing an inert gas into the vacuum preliminary room. CONSTITUTION:After a wafer 5 is withdrawn into an unloading lock 30, a vacuum valve 17 and a vacuum cut valve 10 are closed, and an inert gas (N2 gas) ionized (or heated) by an ionizer (or a heater) 22 is introduced into the unloading lock 30. When the inert gas pressure in the unloading lock 30 is increased to the atmospheric pressure, an atmospheric pressure sensor 26 is operated to sense the atmospheric pressure. A valve 21 is opened and the interior of the unloading lock 30 is exhausted by a coarse exhaust pump 20. The inert gas processed by the ionizer (or the heater) 22 is caused to flow in the unloading lock 30 for a given period of time at about the atmospheric pressure so that the ion concentration or the gas temperature in the atmosphere surrounding the wafer 5 is maintained not less than a given level. The residual reactive gas on the surface of the wafer is dissociated effectively and exhausted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an etching apparatus that etches a metal film on a wafer with a reactive gas turned into plasma, and then processes the wafer with an inert gas.

[Prior Art] FIG. 3 is a schematic diagram showing a conventional etching apparatus. An upper electrode 2 and a lower electrode 3 are disposed in a vacuum processing chamber 1 in which etching is performed, and a wafer 5 to be processed is placed on the lower electrode 3.

The lower electrode 3 is connected to a high frequency (R) installed outside the vacuum processing chamber 1.
F) A power source 4 is connected, and this RF power source 4 supplies high frequency power between the lower electrode 3 and the upper electrode 2. The inside of the vacuum processing chamber 1 is connected to a high vacuum exhaust pump 6 via a valve 18, and this high vacuum exhaust pump 6 is connected to a rotary pump (hereinafter referred to as RP) via a valve 19.
It is connected to 7. As a result, the inside of the vacuum processing chamber 1 is evacuated to a high vacuum.

Vacuum cut valves 11 and 10 are installed on both sides of the vacuum processing chamber 1.
A load lock 8 and an unload lock 9 are provided respectively through the valves 15 and R.
P14 are connected in series. Unload lock 9
The inside is connected to the RP 16 via a valve 17.

In the etching apparatus constructed as described above, first, the wafer 5 to be processed is loaded into the load lock 8 by opening the gate valve 12, and the load lock 8 is evacuated by opening the valve 15.

Next, the vacuum cut valve 11 is opened and the wafer 5 is placed from the load lock 8 onto the lower electrode 3 in the vacuum processing chamber 1 .

By opening the valves 18 and 19, the interior of the vacuum processing chamber 1 is evacuated to a high vacuum state by the high vacuum pump 6 evacuated by the RP 7, and maintained therein.

A predetermined reactive gas is introduced into the vacuum processing chamber 1, and high-frequency power is applied between the upper and lower electrodes 2.3 by the RF power source 4, thereby generating a plasma discharge. The metal film on the wafer 5 is etched by the reactive gas.

On the other hand, the inside of the unload lock 9 is evacuated by the RP 16 by opening the valve 17, and the wafer 5 after the etching process is removed from the unload lock from the vacuum processing chamber 1 by opening the vacuum cut valve 10. 9
moved inward. Then, after closing the vacuum cut valve 10 and closing the valve 17, the gate valve 13 is closed.
The wafer 5 is opened and the processed wafer 5 is taken out. In this case, conventionally, when the etched wafer 5 is discharged from the unload lock 9 into the atmosphere, the wafer 5 is heated by an ionizer (or heater) 22 near the gate valve 13 of the unload lock 9. An inert gas (eg, ionized or heated) (for example, N2 gas) is blown through the gas nozzle 23. Note that there is a method in which the unload lock 9 is directly vacuum-broken with this inert gas to bring the inside of the unload lock 9 to atmospheric pressure.

[Problems to be Solved by the Invention] However, the conventional etching apparatus described above has the following problems when ejecting the processed wafer 5 from the unload lock 9.

In the former case, the process is carried out in the atmosphere, so it is not possible to suppress dust in the atmosphere, and the reactive gas that has not been removed from the wafer surface reacts with the moisture in the atmosphere, causing the wafer to evaporate. The disadvantage is that it corrodes the metal film on top.

In the latter case, the ions of the introduced inert gas become neutralized in a short period of time, and a drop in gas temperature cannot be avoided, so it is effective to remove the reactive gas remaining on the wafer surface. There was a problem that it could not be done.

The present invention has been made in view of such problems, and includes:
It is an object of the present invention to provide an etching apparatus that can effectively dissociate and exhaust reactive gas remaining on the wafer surface and prevent corrosion of the metal film on the wafer.

[Means for Solving the Problems] An etching apparatus according to the present invention includes an etching processing chamber for etching a metal film on a semiconductor wafer with a reactive gas turned into plasma, and a vacuum chamber into which the processed wafer is loaded. It has a preliminary chamber, a rough exhaust pump for evacuating the vacuum preliminary chamber at near atmospheric pressure, and a gas introduction means for introducing an inert gas into the vacuum preliminary chamber. After the active gas is introduced, the vacuum preparatory chamber is evacuated by the rough evacuation pump in parallel with the introduction of the inert gas.

[Function] In the present invention, first, after the etched wafer is transferred to a vacuum preliminary chamber, an inert gas such as an inert gas ionized by an ionizer or an inert gas heated by a heater is heated. Introduce it into the vacuum preliminary chamber. Then, when the inert gas pressure in the vacuum preparatory chamber increases, the vacuum preparatory chamber is evacuated by a rough exhaust pump, and the inert gas is introduced and exhausted in parallel, and the inert gas is brought into the vacuum preparatory chamber at atmospheric pressure, for example. Allow the current to flow for a certain period of time near the

Thereby, the ion concentration or gas temperature of the wafer atmosphere can be maintained at a predetermined level or higher, and the reactive gas remaining on the wafer surface can be effectively dissociated and exhausted. Furthermore, since this treatment can be performed before the wafer is exhausted into the atmosphere, moisture from the atmosphere can be prevented from entering the wafer. Therefore, corrosion of the metal film on the wafer can be prevented.

[Example] Next, an example of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing an etching apparatus according to an embodiment of the present invention.

In FIG. 1, the same parts as those in FIG. 3 are given the same reference numerals, and their explanations will be omitted. The difference between this embodiment and the prior art shown in FIG. 3 is that the unload lock 9 in FIG. The lock 30 is configured so that ionized (or heated) inert gas from the ionizer (or heater) 22 can be introduced into the unload lock 30, and the inside of the unload lock 30 is roughly introduced through the valve 21. It is configured to be able to exhaust air using an exhaust pump 20, and is further provided with an atmospheric pressure sensor 26.

In the apparatus of this embodiment configured as described above, after the wafer 5 is collected into the unload lock 30, the vacuum valve 17 and the vacuum cut valve 10 are closed, and the wafer 5 is ionized by the ionizer (or heater) 22. (or heated) inert gas (N2 gas)
Introduce within 0.

Then, when the inert gas pressure within the unload lock 30 increases to atmospheric pressure, the atmospheric pressure sensor 26 operates and the atmospheric pressure is detected. This sensor 26 causes the unload lock 3
After it is detected that the pressure within the unload lock 30 has reached atmospheric pressure, the valve 21 is opened and the rough exhaust pump 20 is used to pump the inside of the unload lock 30 while continuing to introduce inert gas from the ionizer (or heater) 22. Exhaust.

In this way, the inert gas treated by the ionizer (or heater) 22 is passed through the unload lock 30 at near atmospheric pressure for a certain period of time, and the ion concentration or gas temperature in the atmosphere of the wafer 5 is controlled. hold above a certain level. Thereby, the reactive gas remaining on the wafer surface can be effectively dissociated and exhausted. In addition, since the reactive gas on the wafer surface is removed in this way before the wafer is discharged into the atmosphere, the metal film on the wafer will be corroded due to the reaction between the residual reactive gas and the moisture in the atmosphere. This situation can be avoided.

FIG. 2 shows another embodiment of the invention. This example is the first
This is an improved inert gas introduction boat 24 and exhaust port 25 compared to the unloading rotor shown in the figure. The gas introduction boat 24 is provided with one gas introduction port 26 for each wafer 5, and similarly, the exhaust port 25 is provided with one exhaust port 27 for each wafer 5. ing.

This allows the inert gas to flow effectively over the surface of the wafer 5, which has the advantage that reactive gas remaining on the wafer surface can be removed with higher efficiency.

[Effects of the Invention] As explained above, the present invention allows an inert gas treated with an ionizer or a heater to flow through the vacuum preliminary chamber to maintain the ion concentration or gas temperature at a predetermined level or higher. The dissociation and evacuation of reactive gases remaining on the wafer surface can be performed more effectively than in conventional techniques. Furthermore, since this process can be performed before the wafer is discharged into the atmosphere, it is possible to prevent moisture from the atmosphere from entering during the process.

This can reduce the phenomenon in which the metal film on the wafer is corroded due to the reaction between moisture in the atmosphere and the reactive gas remaining on the wafer surface.

[Brief explanation of the drawing]

Claims (1)

[Claims] (1) an etching chamber for etching a metal film on a semiconductor wafer with a reactive gas turned into plasma;
It has a vacuum preliminary chamber into which the wafer after processing is loaded, a rough exhaust pump that evacuates the vacuum preliminary chamber to near atmospheric pressure, and a gas introduction means that introduces an inert gas into the vacuum preliminary chamber,
An etching apparatus characterized in that, after an inert gas is introduced into the vacuum preliminary chamber by the gas introducing means, the interior of the vacuum preliminary chamber is evacuated by the rough exhaust pump in parallel with the introduction of the inert gas.