JP2005005292A - System and process for fabricating electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device in which fluorides being produced when oxides on the metal surface are removed after forming a contact hole can be removed and production of TiOH can be prevented, and to provide a process for fabricating a semiconductor device. <P>SOLUTION: The system for fabricating an electronic device comprises a processing chamber employing a fluorine based gas for removing an insulating film between interconnect line layers and oxides on the contact surface of a semiconductor, a conveyor for conveying the semiconductor in order to remove fluorine remaining on the contact surface after the insulating film is removed, equipment for heat treating the semiconductor, and a system performing hydrogen based plasma processing of the semiconductor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic device manufacturing system and an electronic device manufacturing method having a function and a process for removing oxide on a contact surface.
[0002]
[Prior art]
FIG. 6 shows a step of forming a contact portion for connecting metal wirings arranged in layers in the manufacturing process of the electronic device.
First, in FIG. 6A, an insulating film 62 such as a silicon oxide film or a nitride film is formed on the lower metal wiring 61, and a resist 63, which is an organic material, is applied on the insulating film 62, and then exposed and developed. The patterning state is shown. For example, Al—Si—Cu is used for the lower wiring 61, and TiN or Ti exists as a barrier metal on the surface thereof.
[0003]
Next, RIE (reactive ion etching) processing is performed using the resist 63 patterned by the plasma of CF-based gas and O-based gas as a mask to form a contact hole 64 (see FIG. 6B).
Next, the resist 63 that is no longer needed is removed by ashing after the contact hole 54 is formed (see FIG. 6C).
[0004]
After removing the ashing of the resist 63, the contact hole 64 is filled with a metal material to be the contact portion 65 (see FIG. 6D), and finally the upper metal wiring 66 is formed, whereby the lower metal wiring 61 and the upper metal wiring are formed. 66 is formed by a contact portion 65 to form a multilayer wiring structure (see FIG. 6E). In this series of processes, the lower metal wiring 61 is exposed at the bottom of the contact hole 64 after the etching shown in FIG. If an operation such as an ashing process is performed with the lower metal wiring 61 exposed, the surface of the lower metal wiring 61 is oxidized, so that the contact resistance increases.
[0005]
Therefore, conventionally, for the purpose of removing the oxide formed on the surface of the lower metal wiring 61, the bottom of the contact hole 64 has been cleaned before the metal material is buried. In the cleaning process, for example, the oxide on the surface of the lower metal wiring 61 is removed by etching process by converting CF ₄ gas into plasma.
[0006]
Although the metal material is embedded in the contact hole 64 after the cleaning process, it has been transported in the atmosphere to transport to the position where the process of embedding from the previous etching process is performed.
[Patent Document 1] JP-A-10-326771 (page 4, FIG. 2)
[0007]
[Problems to be solved by the invention]
However, when the cleaning process is performed, the oxide on the surface of the lower metal wiring 61 can be removed to some extent, but fluoride is generated instead. This is because fluorine contained in the CF ₄ gas used as the processing gas is combined with dangling bonds on the surface of the lower metal wiring 61. When fluoride is generated on the surface of the lower metal wiring 61, the adhesion between the metal material embedded in the contact hole 54 and the lower metal wiring 61 is lowered, and this causes contact resistance between the lower metal wiring 61 and the contact portion 55. The first problem is that it becomes high or unstable.
Further, when the electronic device is transported to move to the step of embedding the metal material in the contact hole 54 after the cleaning process, it is transported in the atmosphere. There was a second problem that the metal wiring 61 had been generated on the surface.
[0008]
The present invention provides an electronic device manufacturing system and an electronic device for the first problem that it is possible to remove fluoride adhering when removing the oxide film formed on the surface of the lower metal wiring 61 after forming the contact hole. Device manufacturing method, and electronic device manufacturing system and electronic device for solving the second problem of avoiding exposure to the atmosphere when transporting an electronic device in order to prevent TiOH from being generated on the surface of metal wiring It is to provide a manufacturing method.
[0009]
[Means for Solving the Problems]
In order to achieve the first object, an electronic device manufacturing system of the present invention includes a first processing chamber for removing oxides on the surface of metal wiring formed in an electronic device using a fluorine-based gas, an oxidation process, A second processing chamber for removing fluoride generated on the surface of the metal wiring when removing an object using a hydrogen-based plasma, and a transport device for transporting the electronic device. It is characterized by being transported in a special atmosphere or in a vacuum.
[0010]
Further, the electronic device manufacturing method of the present invention includes an oxide removing step of removing oxide on the surface of the metal wiring formed on the electronic device using a fluorine-based gas, and the metal wiring at the time of the oxide removing step. Having a fluoride removal step of removing fluoride generated on the surface using a hydrogen-based plasma, and a transfer step of transferring the electronic device, and transferring in a special atmosphere or vacuum in the transfer step It is a feature.
In order to achieve the second object, the transport apparatus transports the electronic device in a special atmosphere or in a vacuum.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an electronic device manufacturing system and an electronic device manufacturing method according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 is an overall configuration diagram of an electronic device manufacturing system, and FIG. 2 is an analysis diagram of a metal wiring surface after etching removal of fluoride generated on the metal wiring surface and after fluoride is removed by downflow plasma, 3 and 4 are graphs showing the relationship between the temperature of an object to be processed (for example, a wafer) and the residual fluorine amount during the fluoride removal process. FIG. 5 shows a step of forming a contact portion for connecting metal wirings arranged in layers in the manufacturing process of the electronic device, and FIGS. 5 (a) (b) (c) (d) (e) 6A, 6B, 6C, 6D, and 6E have the same contents. The difference between FIG. 5 and FIG. 6 is FIG. 5 (c ′). In FIG. 5 (c ′), when the oxide is removed (FIG. 5 (c)), an operation of removing the fluoride generated on the surface of the metal wiring using hydrogen-based plasma is performed.
[0012]
FIG. 1 is an overall configuration diagram of an electronic device manufacturing system showing an apparatus capable of cleaning a contact hole bottom, carrying a vacuum and performing a downflow process, according to the present embodiment. In FIG. 1 is a first plasma processing chamber of, for example, a parallel plate type for removing the oxide film formed on the surface of the lower metal wiring 51 exposed by the above, and shows an outline of P / C1 in the drawing in an enlarged manner. Further, in the description relating to the transfer device in the claims, the upper limit of the atmospheric pressure is 10 ⁻⁶ × 101325/760 Pa in the vacuum, and the special atmosphere is the inert gas (for example, xenon gas, for example) , At least one of helium gas, argon gas, nitrogen gas, and oxygen gas).
[0013]
The first plasma processing chamber 1 is installed in a positional relationship where the upper electrode 11 and the lower electrode 13 face each other. From the upper electrode 11 having means capable of supplying gas, CF-based gas or Ar gas is jetted toward the lower electrode 13 on which the object to be processed can be placed. A high frequency generator 14 is connected to the lower electrode 13 via a matching box 15. A high frequency (for example, 13.56 MHz) is generated by the high frequency generator 14, and CF-based gas or Ar gas is turned into plasma to etch the oxide film formed on the surface of the workpiece placed on the lower electrode 13. To do.
[0014]
Reference numeral 2 in FIG. 1 denotes a second plasma processing chamber for removing fluoride generated when the oxide film formed on the surface of the lower metal wiring 51 in the first plasma processing chamber 1 is etched. The outline of P / C2 is expanded.
In the second plasma processing chamber 2, a waveguide 21 for introducing a microwave is installed in the upper part, and a stage 25 on which an object to be processed can be placed at a position facing the waveguide 21. A heater 26 capable of heating the object to be processed up to 250 degrees, for example, is installed in the lower part.
[0015]
Although not shown, the plasma processing chamber 2 is connected to, for example, a chamber side wall so that a hydrogen-based gas (for example, H ₂ O gas) can be supplied therefrom. The gas is turned into plasma by the microwave supplied from the waveguide 21 and processed by the generated hydrogen radicals. As a result, fluoride generated on the surface of the workpiece is removed.
[0016]
Reference numeral 7 in FIG. 1 denotes a vacuum transfer chamber, which has a transfer robot 71. The transfer robot 71 connects the plasma processing chamber 1, the plasma processing chamber 2, and the cassette chamber 8. For example, the transfer robot 71 takes out a predetermined unprocessed wafer in the present invention from the cassette chamber 8 and transfers it to the plasma processing chamber 1. When processing is completed in the plasma processing chamber 1, the processed wafer is unloaded by the transfer robot 71 and loaded into the plasma processing chamber 2. When the processing in the plasma processing chamber 2 is completed, the processed wafer is unloaded by the transfer robot 71 and transferred to the cassette chamber 8.
[0017]
In these descriptions, the plasma processing chamber 1 is set as a parallel plate type plasma processing chamber, and the plasma processing chamber 2 is set as a downflow type plasma processing chamber. However, other types of plasma processing chambers may be used. .
In this example, the surface of the metal contact forming the wiring is taken as an example, but it can also be used for a silicide surface (eg, TiSi, CoSi, NiSi) which is a compound of silicon and metal, and electricity is passed therethrough. Also used for.
[0018]
Next, the processing flow will be described. A cassette (not shown) storing a plurality of objects to be processed is installed in the cassette chamber (C / C) 8. When the cassette is loaded, the cassette chamber 8 is evacuated, and the wafer in the cassette that has not been processed in the plasma processing chamber 1 is transferred to the plasma processing chamber 1 by the transfer robot 71 of the vacuum transfer chamber 7.
[0019]
In the plasma processing chamber 1, the oxide on the surface of the lower metal wiring 51 of the object to be processed is etched by CF plasma to remove the oxide. The procedure is given below. When an unprocessed object that has been carried in by the transfer robot 71 is placed on the lower electrode 13, the plasma processing chamber 1 and the vacuum transfer chamber 7 are disconnected. In the plasma processing chamber 1, the processing gas (CF gas, Ar gas, etc.) is converted into plasma by the high frequency generator 14, and oxide etching is performed.
[0020]
After completion of the etching process in the plasma processing chamber 1 (see FIG. 5C), the workpiece is transferred to the downflow processing chamber 2 by the transfer robot 71. Since the inside of the vacuum transfer chamber 7 is maintained in a vacuum state (the upper limit of atmospheric pressure is 10 ⁻⁶ × 101325/760 Pa), it is possible to prevent TiOH from being formed on the surface of the lower metal wiring 51 of the object to be processed. it can.
[0021]
In the plasma processing chamber 2, after the oxide film is processed by etching in the plasma processing chamber 1, the fluoride generated in the lower metal wiring 51 at the bottom of the contact hole 54 is removed (see FIG. 5C '). When the object to be processed carried by the transfer robot 71 in the vacuum transfer chamber 7 is placed on the stage 25, the plasma processing chamber 2 and the vacuum transfer chamber 7 are disconnected. In the plasma processing chamber 2, the workpiece placed on the stage 25 is heated by the heater 26, and the processing gas (H ₂ O gas or the like) is converted into plasma by the microwave propagated through the waveguide 21. The The hydrogen radicals generated thereby react with the fluoride adhering to the surface of the lower metal wiring 51 to generate HF, whereby the fluoride is removed.
[0022]
Next, elemental analysis results on the surface of the object to be processed in the plasma processing chamber 1 and the plasma processing chamber 2 will be described.
FIG. 2 shows the analysis result of the metal surface after etching the oxide film on the lower metal wiring 51 at the bottom of the contact hole 54 and the metal surface after the object to be processed is transferred in vacuum after the etching and subjected to downflow plasma processing. , XPS (X-ray Photoelectron Spectroscopy, X-ray photoelectron spectroscopic analyzer) is used to show the results of analysis. XPS refers to examining what molecules are present on an analyte surface by applying X-rays to the analyte surface, detecting excited and emitted electrons, and analyzing the energy state.
[0023]
The vertical axis in FIG. 2 indicates the detected amount of electrons (the unit is the number of electrons), and the horizontal axis indicates the strength of coupling. The lower graph shows the result of elemental analysis of the surface of the lower metal wiring 51 at the bottom of the contact hole 54 of the object to be processed, which has been subjected to oxide etching using fluorine-based plasma in the plasma processing chamber 1. As is clear from the graph, a high value is shown in the vicinity of 685 (eV) indicating the binding energy of fluorine. That is, it can be seen that fluoride remains on the surface of the lower metal wiring 51.
[0024]
Next, the upper graph in FIG. 2 shows the surface of the lower metal wiring 51 at the bottom of the contact hole 54 of the object after the fluoride is removed by the hydrogen radical process in the plasma processing chamber 2. It is an elemental analysis result. While the lower graph in FIG. 2 shows a high value in the vicinity of 685 (eV), such a situation is not seen in the upper graph. Therefore, it turns out that fluoride is removed.
[0025]
Further, the relationship between the temperature of the object to be processed on the stage 25 by the heater 26 when performing the fluoride removing process in the second plasma processing chamber 2 and the residual amount of fluorine after the removal will be described. 3 (the vertical axis indicates the detected amount of electrons (unit is the number of electrons), the horizontal axis indicates the strength of bonding, asRIE in the figure indicates before heating) and FIG. 4 (the vertical axis indicates the detected amount (unit: When the surface temperature of the object to be processed is 200 ° C. or more, it can be seen that the residual amount of fluorine can be removed below the detection limit of the XPS analysis.
[0026]
By performing these treatments, it is possible to remove the oxide generated on the surface of the lower metal wiring 51 at the bottom of the contact hole 54. Further, it is possible to remove the fluoride remaining after the oxide etching process, and in addition, the object to be treated is conveyed. TiOH is not produced at any time, and a clean metal surface is obtained.
[0027]
【The invention's effect】
According to the present invention, the oxide on the metal surface can be reduced to the level of a natural oxide film, and fluoride can be removed to obtain a clean metal surface.
[Brief description of the drawings]
FIG. 1 is a layout view of an electronic device manufacturing system according to the present invention.
FIG. 2 is a fluorine spectrum diagram of the surface of a metal wiring at the bottom of a contact hole after downflow processing and after CF ₄ etching.
FIG. 3 is an analysis result diagram of the surface after etching the insulating film on the metal wiring at the bottom of the contact hole.
FIG. 4 is a graph showing the relationship between the amount of fluorine on the metal surface and the temperature after downflow plasma treatment.
FIG. 5 is a flowchart of contact hole formation according to the present invention.
FIG. 6 is a flowchart of conventional contact hole formation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Plasma processing chamber, 2 ... Plasma processing chamber, 7 ... Vacuum transfer chamber, 8 ... Cassette chamber, 11 ... Upper electrode, 13 ... Lower electrode, 14 ... High frequency Generating device, 15 ... matching box, 21 ... waveguide, 25 ... stage, 26 ... heater, 51 ... lower metal wiring, 52 ... insulating film, 53 ... resist 54 ... contact hole, 55 ... contact part, 56 ... upper metal wiring, 61 ... lower metal wiring, 62 ... insulating film, 63 ... resist, 64 ... contact hole , 65... Contact part, 66... Upper metal wiring, 71.

Claims (9)

A first processing chamber for removing oxide on the surface of the metal wiring formed in the electronic device using a fluorine-based gas;
A second processing chamber for removing the fluoride generated on the surface of the metal wiring when removing the oxide using a hydrogen-based plasma;
An electronic device manufacturing system comprising: a transport device that transports the electronic device. The electronic device manufacturing system according to claim 1, wherein the transport device transports the electronic device in a special atmosphere. The electronic device manufacturing system according to claim 1, wherein the transport device transports the electronic device in a vacuum. The electronic device manufacturing system according to claim 1, wherein the second processing chamber includes a heat processing unit for heating the electronic device. The electronic device manufacturing system according to claim 1, wherein a heating temperature in the heat treatment means is 200 ° C. or more. An oxide removal step of removing oxide on the surface of the metal wiring formed on the electronic device using a fluorine-based gas;
A fluoride removing step of removing fluoride generated on the surface of the metal wiring using a hydrogen-based plasma in the oxide removing step;
An electronic device manufacturing method comprising: a transporting process for transporting the electronic device. The electronic device manufacturing method according to claim 6, wherein the transporting step transports the electronic device under a special atmosphere. The electronic device manufacturing method according to claim 6, wherein the transporting step transports the electronic device in a vacuum. The contact hole is formed in the said electronic device, The said conveyance process is a process of conveying to the process of embedding a metal in the said contact hole, Either of Claim 7 or Claim 8 characterized by the above-mentioned. The electronic device manufacturing method as described in any one of Claims 1-3.

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