JP2008140880A - Method of forming thin film, deposition apparatus and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film forming apparatus that can deposit a copper thin film in high controllability of film thickness and at high film formation rate while burying micro recessed parts by using organic acid copper as a material. <P>SOLUTION: The deposition apparatus 20 that form a thin film on the surface of a workpiece W includes: a processing container 22 that can be discharged; a placement table 24 to place the workpiece; a heating means 26 to heat the workpiece; a gas introduction part 56 that is provided in the processing container to introduce a gas into the processing container; a material gas supply means 68 to feed gaseous organic acid copper into the gas introduction part; and an apparatus control part 100 to control the operation of the entire apparatus. Thus, the deposition apparatus forms a copper film as a thin film on the surface of the workpiece. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thin film forming method for forming a copper film as a thin film on the surface of an object to be processed such as a semiconductor wafer, a film forming apparatus, and a storage medium for storing a control program.

  In general, in order to manufacture a semiconductor device, a desired device is manufactured by repeatedly performing various processes such as a film forming process and a pattern etching process on a target object such as a semiconductor wafer. In addition, line widths and hole diameters are becoming increasingly finer due to the demand for higher miniaturization. As the wiring material and the embedding material, there is a tendency to use copper that is very low in electrical resistance and inexpensive because the electrical resistance needs to be further reduced by miniaturization of various dimensions (Patent Documents 1, 2, and 3). ).

In order to deposit such copper as a thin film, generally, a seed film is formed by a plasma sputtering process using copper as a metal target, and a plating process is performed by applying electricity to the seed film to thereby form a copper thin film. Has been made to form.
In this method of forming a copper thin film by plating, as the groove width and hole diameter become 65 nm, 45 nm, or 32 nm as the size of the groove gradually decreases, the plating solution becomes difficult to enter the groove or hole. The plating process itself could not be performed. Therefore, recently, since it has excellent covering properties and excellent ability to fill in narrow grooves and holes (holes), the copper thin film is formed by a CVD (Chemical Vapor Deposition) method. A method has also been proposed (Patent Document 4).

  In this method of forming a copper film by the CVD method, for example, a raw material of a complex that becomes liquid at room temperature, such as Cu (I) hfacTMVS, is vaporized by bubbling or the like, and is formed on the semiconductor wafer by the CVD method. A copper thin film is deposited on the substrate.

JP 2000-77365 A JP-A-10-74760 JP-A-10-214836 JP 2001-53030 A

  By the way, the copper complex raw material as described above is very reactive and has a very low thermal stability, so it easily decomposes, and therefore, agglomeration of copper easily occurs in the processing vessel. It was difficult to form a copper film with a uniform thickness and good controllability. In addition, for the reasons described above, there has been a problem that the complex source gas is thermally decomposed in the middle of conveyance, although the conveyance path of the complex source gas is maintained at a temperature higher than the theoretical thermal decomposition temperature.

  For this reason, the process temperature is controlled as low as possible so that it is not easily decomposed, but in this case, not only the film formation rate becomes very low but also the carbon component in the copper film. As a result, the resistance of the copper film increases and the physical properties deteriorate.

  The present invention has been devised to pay attention to the above problems and to effectively solve them. An object of the present invention is to provide a method for forming a thin film by using organic acid copper as a raw material so that a thin copper film can be deposited with high film thickness controllability while embedding fine recesses, and at a high film formation rate. It is to provide a membrane device and a storage medium.

As a result of earnest research on the film formation method of the copper film, the present inventor can stably form the copper film by the CVD method with good controllability by using organic acid copper typified by copper acetate as a raw material. This has led to the present invention.
The invention according to claim 1 is the method of forming a thin film on the surface of the object to be processed, wherein the organic acid copper is heated to a temperature T1 to form a gas, and the gas is maintained at a temperature T2 higher than the temperature T1. A method of forming a thin film, comprising a step of forming a copper film that is supplied onto a treatment body and forms a copper film as the thin film on the surface of the object to be treated.
As described above, by using organic acid copper as a raw material, a copper thin film can be deposited at a high film formation rate with good film thickness controllability while filling fine concave portions.

In this case, for example, as described in claim 2, the temperature T1 is a temperature at which the organic acid copper does not decompose.
For example, as described in claim 3, the temperature T1 is 300 ° C. or less.
For example, as described in claim 4, an insulating layer is formed in advance on the surface of the object to be processed, and a recess is formed in the insulating layer.
For example, as described in claim 5, a barrier layer is formed in advance on the surface of the insulating layer including the surface in the recess.

Further, for example, as described in claim 6, after the copper film forming step, a copper film removing step of exposing the surface of the barrier layer by removing a copper film other than the copper film formed in the concave portion is performed.
For example, as described in claim 7, in the copper film removal step, an etching process using an organic acid is performed in a state where the object to be processed is maintained at a predetermined temperature T3.
Thus, when performing the etching process using an organic acid, the etching process can be continuously performed from the formation process of the copper film in the same processing container.
For example, as described in claim 8, the relationship between the temperatures T2 and T3 is T2 ≦ T3, which is 400 ° C. or less.

For example, as described in claim 9, in the copper film removing step, a plasma sputtering process for roughening the surface of the copper film is performed as a pre-process for the etching process.
Further, for example, in the plasma sputtering process, an oxidizing gas for oxidizing the surface of the copper film is added.
For example, as described in claim 11, the copper film removing step performs a chemical mechanical polishing (CMP) process.
For example, as described in claim 12, after the copper film removing step, a barrier layer removing step of removing the barrier layer exposed on the surface of the object to be processed is performed.

  According to the invention of claim 13, in the method of forming a thin film on the surface of the object to be processed, an insulating layer forming step for forming an insulating layer on the surface of the object to be processed, and a recess for forming a recess in the insulating layer A barrier layer forming step of forming a barrier layer on the surface of the insulating layer including the surface in the recess, and removing a barrier layer other than the barrier layer formed on the surface in the recess to form a lower layer A barrier layer removing step for exposing the insulating layer, and heating the surface of the object to be processed to selectively heat the remaining barrier layer with respect to the exposed insulating layer. The organic acid copper is heated to a temperature T1 to form a gas, and the gas is supplied onto the object to be processed to fill the inside of the concave portion while the copper film is formed as the thin film on the surface of the barrier layer. A copper film forming step for forming A method for forming a thin film characterized.

In this case, for example, as described in claim 14, the temperature T1 is a temperature at which the organic acid copper does not decompose.
For example, as described in claim 15, the temperature T1 is 300 ° C. or less.
Further, for example, as described in claim 16, after the copper film formation step, a copper film removal step of removing an excess copper film is performed.
Further, for example, as described in claim 17, in the copper film removing step, an etching process using an organic acid is performed while maintaining the object to be processed at a predetermined temperature T3.

For example, as described in claim 18, the relationship between the temperatures T2 and T3 is T2 ≦ T3, which is 400 ° C. or less.
Further, for example, in the copper film removing step, a plasma sputtering process for roughening the surface of the copper film is performed as a pre-process for the etching process.
For example, as described in claim 20, in the plasma sputtering process, an oxidizing gas for oxidizing the surface of the copper film is added.
Further, for example, as described in claim 21, the copper film removing step performs chemical mechanical polishing (CMP).

Further, for example, as described in claim 22, the organic acid copper is made of one or more materials selected from the group consisting of copper acetate, copper formate, copper propionate, and copper 2-ethylhexate.
Further, for example, as described in claim 23, the organic acid is one or more materials selected from the group consisting of acetic acid, formic acid, propionic acid, valeric acid, oxalic acid, malonic acid, and 2-ethylhexic acid. It becomes more.

  According to the invention of claim 24, in the film forming apparatus for forming a thin film on the surface of the object to be processed, a processing container which is made evacuable, a mounting table for mounting the object to be processed, and the object to be processed A heating means for heating the treatment body, a gas introduction part provided in the treatment container for introducing gas into the treatment container, and a raw material gas for supplying gaseous organic acid copper to the gas introduction part A film forming apparatus comprising: a supply unit; and an apparatus control unit that controls operation of the entire apparatus, and configured to form a copper film as the thin film on a surface of the object to be processed.

In this case, as described in, for example, claim 25, the heating means includes a resistance heater provided on the mounting table.
In addition, for example, as described in claim 26, the heating means includes a heating lamp portion that emits light for heating.
For example, as described in claim 27, the heating lamp section emits light that can be selectively heated according to the material of the surface of the object to be processed.
Further, for example, as described in claim 28, the processing vessel is provided with plasma forming means for generating plasma.

  According to the 29th aspect of the present invention, a processing container that can be evacuated, a mounting table for mounting the object to be processed, a heating means for heating the object to be processed, and the processing container are provided. A gas introduction unit for introducing gas into the processing vessel, a raw material gas supply means for supplying gaseous organic acid copper to the gas introduction unit, and an apparatus control unit for controlling the operation of the entire apparatus. When forming a thin film on the surface of the object to be processed using the film forming apparatus, the organic acid copper is heated to a temperature T1 to form a gas, and the gas is maintained at a temperature T2 higher than the temperature T1. A storage medium storing a program for controlling the film forming apparatus to be supplied onto a body and to form a copper film as the thin film on the surface of the object to be processed.

According to the thin film forming method, the film forming apparatus, and the storage medium according to the present invention, the following excellent operational effects can be exhibited.
By using organic acid copper as a raw material, a copper thin film can be deposited at a high film formation rate with good film thickness controllability while filling fine concave portions.
In particular, according to the invention according to claim 7, since the etching process using the organic acid is performed, the etching process can be continuously performed from the formation process of the copper film in the same processing container.

In the following, an embodiment of the thin film forming method, film forming apparatus and storage medium according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic explanatory view showing a basic film forming apparatus for explaining a basic principle of a thin film forming method according to the present invention.

As shown in FIG. 1, this film forming apparatus has a cylindrical processing container 2 made of a heat-resistant material such as quartz. A carrier gas nozzle 4 for supplying a carrier gas is provided at one end of the processing container 2 so that, for example, N ₂ gas can be supplied as the carrier gas while controlling the flow rate. Note that a rare gas such as Ar or He may be used as the carrier gas, or H ₂ gas may be used. Further, an exhaust port 6 is provided at the other end of the processing container 2 so that the inside of the processing container 2 can be exhausted by a vacuum pump or the like (not shown).

  A raw material container 8 with a built-in heater is provided on the upstream side of the gas flow in the processing container 2, and the organic acid copper 10 is accommodated in the raw material container 8 as a film forming raw material. . As the organic acid copper 10, for example, copper acetate that is solid at room temperature can be used. Then, the raw material container 8 is heated to, for example, about 250 ° C. by the heating system 12, so that the organic acid copper 10 is sublimated into a gas.

Further, on the downstream side of the processing container 2, a mounting table 14 having a built-in heater is provided, and, for example, a semiconductor wafer W is mounted thereon as an object to be processed. The mounting table 14 is heated by a heating system 16 to heat the wafer W to a desired temperature, for example, about 300 ° C.
In the fundamental film forming apparatus configured as described above, by heating the organic acid copper 10 in the raw material container 8 at about 250 ° C., the organic acid copper 10 is sublimated without being decomposed to form a gas (gas). And flows downstream with the N ₂ gas introduced from the carrier gas nozzle 4.

The gas of the organic acid copper 10 that has flowed to the downstream side adheres to the surface of the wafer W that is heated and maintained at, for example, about 300 ° C. on the mounting table 14, where, for example, a CVD (Chemical Vapor Deposition) reaction occurs. It decomposes to generate CO ₂ , H ₂ O, etc. As a result, a copper thin film is deposited on the surface of the wafer W. The film formation rate at this time is relatively large, and the copper thin film has a tendency to be uniformly formed on the surface of the wafer W without being deposited unevenly unlike the conventional film formation method. It becomes possible to increase the in-plane uniformity of thickness.

Further, in this example of the apparatus, the organic acid copper 10 is removed or maintained at a low temperature so as not to sublimate, and this is heated to about 300 ° C. by flowing an organic acid such as acetic acid instead of N ₂ gas. When contacted with the copper film of the wafer W, an organic acid copper (copper acetate) is generated opposite to the reaction described above, and the previously deposited copper film is etched to remove unnecessary portions. . As a result, the recesses such as grooves and holes formed on the wafer W can be continuously embedded and etched. Note that the etching rate during the etching process can be improved by roughening the surface of the copper film by plasma sputtering or the like immediately before the etching process of the copper film with the organic acid.

<First Example of Film Forming Apparatus>
Next, a first embodiment of the film forming apparatus according to the present invention will be described. FIG. 2 is a block diagram showing a first embodiment of the film forming apparatus according to the present invention. Here, a description will be given of a film forming apparatus that can perform plasma processing in addition to thermal CVD processing.
As shown in the figure, the film forming apparatus 20 has a processing container 22 formed into a cylindrical shape by, for example, an aluminum alloy, and the processing container 22 is grounded. In the processing container 22, a mounting table 24 made of, for example, an aluminum alloy is provided upright from the bottom of the container, and a semiconductor wafer W, for example, can be mounted on the upper surface of the mounting table 24 as an object to be processed. ing.

  A heating unit 26 made of, for example, a resistance heater is embedded in the mounting table 24, and a heating power source 30 is connected to the heating unit 26 via a power supply line 28. Thereby, the wafer W mounted on the mounting table 24 is heated to a desired temperature.

  In addition, the mounting table 24 is provided with three pin insertion holes 32 (only two are shown in the illustrated example) that are equally arranged in the circumferential direction. Further, below the mounting table 24, lift pins 33 are arranged corresponding to the pin insertion holes 32. The lift pins 33 are connected in common by a ring member 34. The elevating rod 36 penetrating the bottom of the container can be moved up and down. Accordingly, when the wafer W is placed on the mounting table 24, the lifting pins 33 are inserted into the pin insertion holes 32 so as to protrude upward and downward from the upper surface of the mounting table 24, thereby lifting the wafer W in the horizontal direction. The wafer W can be transferred to and from a transfer arm (not shown) that enters from.

  In this case, an elevating actuator 38 is provided at the lower part of the elevating rod 36, and the vertical portion of the elevating rod 36 is maintained at the penetrating portion of the elevating rod 36 with respect to the bottom of the container while maintaining airtightness in the processing container 22. A metal telescopic bellows 40 that allows movement is provided.

  An opening 42 for carrying in and out the wafer W is formed on the side wall of the processing container 22, and a gate valve 44 is provided in the opening 42. An exhaust port 46 is provided at the bottom of the container, and an exhaust system 48 for exhausting the atmosphere in the processing container 22 is provided at the exhaust port 46. The exhaust system 48 is configured by sequentially providing a pressure control valve 52, an exhaust pump 54, and the like in an exhaust passage 50 connected to the exhaust port 46. By using a vacuum pump as the exhaust pump 54, for example. The inside of the processing container 22 can be evacuated.

  The processing container 22 is provided with a gas introduction part 56 for introducing a predetermined gas into the processing container 22. Specifically, a large opening 58 is formed in the ceiling portion of the processing container 22, and a hollow shower head portion 60 serving as the gas introduction portion 56 is provided in the opening 58 via an insulating member 62. It has been. A large number of gas injection holes 64 are formed in the gas injection surface on the lower surface of the shower head portion 60, and gas can be injected from the gas injection holes 64 toward the processing space S below. Further, a gas supply port 66 for supplying gas to the ceiling portion of the shower head unit 60 is provided.

  The shower head unit 60 is connected to raw material gas introduction means 68 for supplying organic acid copper made into a gas. Specifically, the raw material gas introduction means 68 has a gas passage 70 extending from the gas supply port 66, and an open / close valve 71 is interposed in the gas passage 70. The proximal end is connected to the raw material tank 72. In this raw material tank 72, organic acid copper 74 is accommodated as a raw material for forming a copper film. Here, copper acetate 74A is used as a kind of organic acid copper 74. Since the copper acetate 74A is a solid at normal temperature, a heater 76 is provided in the raw material tank 72 in order to sublimate the solid into a gas. Further, a tape heater 78 is wound around the gas passage 70 to prevent the copper acetate 74A conveyed in the form of gas from condensing, and the gas passage 70 is heated to a predetermined temperature. It has become.

A carrier gas passage 80 is connected to the raw material tank 72, and an on-off valve 82 and a flow rate controller 83 such as a mass flow controller are sequentially provided in the carrier gas passage 80 so that the carrier gas is supplied. It can be supplied while controlling the flow rate. As this carrier gas, an inert gas such as N ₂ gas, a rare gas such as Ar, He, or the like, or H ₂ gas can be used.

  Further, another gas passage 84 is connected to the gas supply port 66 of the shower head unit 60, and this gas passage 84 is branched into three on the way. The first branch path 84A is provided with an on-off valve 86 and a flow rate controller 88 such as a mass flow controller in the middle so that the organic acid can be supplied while controlling the flow rate as necessary. . Here, acetic acid is used as the organic acid.

In addition, the second branch passage 84B is provided with an on-off valve 90 and a flow rate controller 92 such as a mass flow controller in the middle so that plasma gas can be supplied while controlling the flow rate as necessary. . Here, Ar gas which is a rare gas is used as the plasma gas, but other rare gas such as He may be used. Further, the third branch path 84C is provided with an on-off valve 94 and a flow rate controller 96 such as a mass flow controller in the middle so that the oxidizing gas can be supplied while controlling the flow rate as necessary. . Here, O ₂ gas is used as the oxidizing gas.

  Further, a high frequency generation source 98 that generates a high frequency of 13.56 MHz, for example, is connected to the shower head 60 that is insulated from the processing vessel 22 by the insulating member 62. Thus, plasma can be generated by applying a high frequency between the two electrodes as necessary, with the shower head 60 as an upper electrode and the mounting table 24 as a lower electrode. In the case where plasma processing is not performed, it is not necessary to provide the high frequency generation source 98.

  The control of each component of the device is performed by the device control unit 100, and is controlled based on, for example, a program created in advance. At this time, for example, a program including instructions for controlling each component is stored in the storage medium 102 such as a flexible disk, a compact disk, a flash memory, or a hard disk.

Next, a method of forming a thin film according to the method of the present invention performed using the film forming apparatus 20 configured as described above will be described with reference to other drawings.
FIG. 3 is a graph showing a TG (Thermogravimetry) curve (thermogravimetric analysis curve) of copper acetate (anhydrous) [Cu (CH ₃ COO) ₂ ], and FIG. 4 is for explaining a first embodiment of a thin film forming method. FIG. 5 is a process diagram for explaining the second embodiment of the thin film forming method, FIG. 6 is a process diagram for explaining the third embodiment of the thin film forming method, and FIG. 7 is the surface of the copper film. FIG. 8 is a flowchart showing first to third embodiments of the thin film forming method, and FIG. 9 is a flowchart showing an aspect of a copper film removing step.

<First Example of Thin Film Forming Method>
First, a first embodiment of the thin film forming method will be described.
Actually, the following processing is performed on the semiconductor wafer W before forming the copper film. First, as shown in FIG. 4A, on the surface of the semiconductor wafer W, for example, a lower wiring layer 110 to be electrically connected is formed in a pattern. The wiring layer 110 may correspond to an electrode of an element such as a transistor or a capacitor.

Then, an insulating layer forming step for forming an insulating layer 112 with a predetermined thickness is performed on the surface of the wafer W as shown in FIG. 4B (S1 in FIG. 8). The insulating layer 112 is made of, for example, SiO ₂ or SiOC.
Next, as shown in FIG. 4C, the insulating layer 112 is subjected to a recess forming step for forming a recess 114 corresponding to the lower wiring layer 110 as shown in FIG. 4C (S2 in FIG. 8). ). The recess 114 is formed in a groove shape or a hole shape, and the wiring layer 110 is exposed at the bottom thereof.

Next, as shown in FIG. 4D, a barrier layer is formed by forming a barrier layer with a predetermined thickness on the entire surface of the insulating layer 112 including the entire surface in the recess 114 using, for example, a sputtering apparatus. A process is performed (S3 in FIG. 4). The barrier layer 116 has a two-layer structure in which a TaN film and a Ta film are sequentially stacked.
When the barrier layer 116 is formed in this way, a copper film forming step for forming the copper film 118 is performed as shown in FIG. 4E using the thin film forming apparatus 20 described in FIG. 8 S4).

Specifically, the wafer W on which the barrier layer 116 is formed is loaded into the processing container 22 of the film forming apparatus 20 shown in FIG. 2, and the wafer W is mounted on the mounting table 24. The inside is hermetically sealed and a copper film forming process is started.
The inside of the processing container 22 is evacuated in advance and maintained at a predetermined process pressure, for example, by driving the exhaust system 48, and the wafer W is brought to a predetermined temperature T2 by the heating means 26 provided on the mounting table 24. Maintained.

In this state, the heater 76 is driven in the raw material tank 72 of the raw material gas introduction means 68 to heat the copper acetate 74 accommodated in the raw material tank 72 to a predetermined temperature T1, whereby the copper acetate 74A is The gas of the copper acetate 74A is transported in the gas passage 70 by the carrier gas (N ₂ gas) supplied while the flow rate is controlled. The copper acetate 74A gas transported by this carrier gas is supplied into the shower head portion 60 of the gas introduction portion 56, diffuses in the shower head portion 60, and is injected into the processing space S from each gas injection hole 64. Will be.

The gaseous copper acetate 74A adheres to the surface of the wafer W and then decomposes to generate CO ₂ and H ₂ O, and a copper thin film (copper film) is deposited on the surface of the wafer W. That is, a copper film is deposited on the surface of the wafer W by thermal CVD using the copper acetate 74A as a raw material.

  Here, the TG curve of the above-mentioned copper acetate (anhydrous) 74A is as shown in FIG. 3, and solid copper acetate begins to sublime when it begins to exceed 200 ° C., and then sublimes rapidly after exceeding 250 ° C. However, until the temperature reaches 300 ° C., the total amount thereof sublimates. In this case, the copper complex raw material used in the conventional film formation method had a tendency to decompose into other substances relatively easily when vaporized into a gas, but this organic acid copper acetate was sublimated. Even if it becomes a gas, it is transported while maintaining the molecular state of copper acetate without being easily decomposed, and adheres to the surface of the wafer W. Accordingly, since the film is stably formed, the film is not unevenly deposited, and the copper film 118 can be formed with high film thickness uniformity.

In addition, the formed copper film 118 has few impurities such as a carbon component and an oxygen component contained therein, is in a sufficiently low resistance state, and has good electrical characteristics.
In addition, copper acetate has a relatively high vapor pressure, and the deposition rate can be kept high because the dilution rate with an inert gas such as N ₂ can be changed significantly. In particular, since the copper film is formed by the CVD method, the recess 114 such as a fine groove having a groove width of 65 nm or less or a fine hole having a diameter of 65 nm or less can be sufficiently filled without generating a void. .

Here, the heating temperature T1 of the copper acetate 74A in the raw material tank 72 is equal to or higher than the sublimation temperature of the raw material and does not thermally decompose, and is within the range of 200 to 300 ° C. as judged from FIG. Preferably, it is in the range of 200 to 250 ° C. If the temperature T1 is higher than 300 ° C., copper acetate itself may be decomposed, which is not preferable.
Further, the temperature T2 of the wafer W at the time of forming the copper film is set to a temperature higher than the temperature T1. Specifically, it exists in the range of 250-400 degreeC. Here, the copper film 118 is formed by thermal CVD. At this time, Ar gas is supplied into the processing chamber 22 as a plasma gas, and the high-frequency power source 98 is driven to generate plasma in the processing space S. The copper film 118 may be formed by plasma CVD processing.

  After completing the copper film formation process as described above, next, as shown in FIG. 4F, the surface of the copper film 118 is removed except for the portion of the copper film embedded in the recess 114. Then, a copper film removing step for exposing the surface of the barrier layer 116 is performed (S5 in FIG. 8). By this step, the copper embedded in the recess 114 remains, but the copper film 118 formed on the surface of the barrier layer 116 is removed to be in a planar state.

  In this case, in the copper film removing step, two methods of modes 1 and 2 can be used as shown in FIG. Aspect 1 utilizes a reaction in which copper is etched when high-temperature copper comes into contact with an organic acid, and the reaction opposite to that in the copper film forming process described above is utilized. ing. Specifically, in the case of the aspect 1, the supply of the copper acetate 74A from the raw material gas introducing means 68 is stopped, and instead, the acetic acid which is an organic acid is supplied while controlling the flow rate, and this is supplied to the shower head unit. 60 is supplied to the processing space S (S5-A in FIG. 9). At this time, the wafer W is maintained at a predetermined temperature T3. The relationship between the temperature T3 at this time and the temperature T2 during the previous film formation is set to satisfy “T3 ≧ T2”. Here, the temperature T3 is in the range of 200 to 300 ° C. As a result, when the heated copper and acetic acid come into contact with each other, a reverse reaction occurs with the above-described copper film formation, and copper acetate is formed. Processing will be performed.

  In the case of the aspect 2, before the wafer W is exposed to acetic acid as in the aspect 1, the surface of the copper film 118 is roughened by performing a plasma sputtering process (S5-B in FIG. 9). That is, the supply of copper acetate, which is a raw material gas, from the raw material gas introducing means 68 is stopped, and instead, Ar gas is supplied as a plasma gas while controlling the flow rate, and this is introduced into the processing space S from the shower head 60. To do. At the same time, the high-frequency generation source 98 is driven to apply high-frequency power between the upper and lower electrodes, that is, between the shower head unit 60 and the mounting table 24 to form plasma in the processing space S. Plasma sputtering is performed on the surface of the copper film 118. As a result, fine irregularities 120 are formed on the surface of the copper film 118 as shown in FIG.

  Next, an etching process using an organic acid having the same contents as in step S5-A described above is performed (S5-C in FIG. 9). According to this, since the fine irregularities 120 are formed on the surface of the copper film 118, the etching rate can be improved accordingly.

Further, in the plasma sputtering process shown in step S5-B, if a small amount of O ₂ gas is supplied as an oxidizing gas together with the Ar gas to the processing space S while controlling the flow rate, the copper is oxidized and the etching rate is increased. Can be further increased. Thus, in this embodiment, the copper film forming step and the copper film removing step can be performed in the same apparatus. The plasma sputtering process may be performed in another plasma apparatus provided so that the wafer W can be transferred without breaking the vacuum. As a specific example, for example, a film forming apparatus and a plasma processing apparatus are commonly connected to a transfer chamber that is evacuated, and the wafer is transferred between the processing apparatuses via the transfer chamber. A so-called cluster device can be used.

Here, the copper film 118 is removed using an organic acid, but instead, the copper film 118 may be removed by a CMP (Chemical Mechanical Polishing) process.
After the copper film removal process is completed in this way, next, as shown in FIG. 4G, a barrier layer removal process for removing the unnecessary barrier layer 116 exposed on the wafer surface is performed (FIG. 4). 8 S6). As a result, the barrier layer 116 remains only in the portion of the copper film 118 embedded in the recess 114. In this barrier layer removal step, for example, the CMP process as described above may be performed. When the CMP process is used in the copper film removing process, the barrier layer removing process can be continuously performed by the CMP process.

  Thus, according to the present invention, by using organic acid copper as a raw material, it is possible to deposit a copper thin film with high film thickness controllability while filling fine concave portions.

<Second Example of Thin Film Forming Method>
Next, a second embodiment of the thin film forming method will be described with reference to FIG.
In the second embodiment, as shown in FIG. 8, the same applies up to the barrier layer forming step of step S3 of the first embodiment, and the structure shown in FIG. 5A is the same as the structure shown in FIG. As shown, a barrier layer 116 is formed on the entire wafer surface.
After the barrier layer 116 is formed in this way, next, as shown in FIG. 5B, a barrier layer removing step for removing the unnecessary barrier layer 116 exposed on the wafer surface is performed (FIG. 5B). 8 S7). As a result, only the barrier layer 116 formed on the surface in the recess 114 remains. In this barrier layer removing step, for example, the CMP process as described above may be performed.

Next, as shown in FIG. 5C, a copper film forming step (S8 in FIG. 8) and a copper film removing step (S9 in FIG. 8) shown in FIG.
The copper film forming step (S8 in FIG. 8) and the copper film removing step (S9 in FIG. 8) are the same as the copper film forming step (S4 in FIG. 8) and the copper film removing step (FIG. 8 in FIG. 8). The contents are the same as those in S5), and are applied as they are here, thereby completing the film forming process. In the case of the second embodiment, the same effects as those of the first embodiment can be exhibited.

<Third embodiment of thin film forming method>
Next, a third embodiment of the thin film forming method will be described with reference to FIG.
In the third embodiment, as shown in FIG. 8, the same applies up to the barrier layer removing step of step S7 of the second embodiment, and the structure is the same as that shown in FIG. 5B. As shown in FIG. 5, the barrier layer on the wafer surface is removed, and only the barrier layer 116 on the surface in the recess 114 is left and formed.

  When the barrier layer removing step is completed in this manner, a copper film forming step is then performed as shown in FIG. 6B (S10 in FIG. 8). The copper film forming step in this case is selectively formed on the remaining barrier layer 116, unlike the first and second embodiments in which the copper film 118 is formed on the entire wafer surface. That is, the surface of the wafer W is irradiated with heating light, the remaining barrier layer 116 is selectively heated with respect to the exposed insulating layer 112, and the barrier layer 116 is heated to a predetermined temperature T2. At the same time, copper acetate is heated to a temperature T1 to form a gas, and this gas is supplied to the wafer W to fill the recess 114 and form a copper film 118 on the surface of the barrier layer 116.

  Specifically, for example, a heating lamp 130 that emits light of a predetermined wavelength is provided as a heating means on the ceiling portion of the processing container 22 shown in FIG. 2, and the heating lamp 130 is made of quartz or the like. The transparent plate 132 partitions the processing space S in an airtight manner. As the wavelength of this light, a wavelength that is easily absorbed by the barrier layer 116 and hardly absorbed by the insulating layer 112 is used. As a result, light emitted from the heating lamp 130 is irradiated onto the surface of the wafer W, and only the barrier layer 116 is selectively used by utilizing the difference in light absorption between the insulating layer 112 and the barrier layer 116 on the wafer surface. Heating is performed, and this temperature is maintained at the same temperature T2 as described above that enables film formation. At this time, the insulating layer 112 is not heated so much and is heated only to a temperature lower than the temperature T2 at which film formation is impossible. Therefore, a copper film is not formed on the surface of the insulating layer 112, and the copper film 118 is selectively formed only on the surface of the barrier layer 116 heated to the temperature T2, resulting in FIG. As shown in FIG. 5B, the recess 114 is filled with the copper film 118.

In this case, as the heating lamp 130, for example, a heating lamp that mainly emits light having a wavelength of 1000 nm or more is preferably used. The ranges of the temperatures T1 and T2 are the same as described above.
In this case, as shown in FIG. 6 (B), an excessive copper film 118A tends to be formed on the upper surface of the copper film 118 so as to protrude upward in a convex shape. As shown in FIG. 8C, a copper film removing step for removing the excess copper film 118A and flattening the surface is performed (S11 in FIG. 8).
This copper film removing step (S11 in FIG. 8) has the same contents as the copper film removing step (S5 in FIG. 8) of the first embodiment, and is applied as it is. This completes the film forming process. In the case of the third embodiment, the same operational effects as those of the first embodiment can be exhibited.

  In the film forming apparatus used in the third embodiment, since the heating lamp 130 is provided, the heating means 26 may not be provided on the mounting table 24 or may be provided. When this heating means 26 is provided, it can be used as an auxiliary heating means for heating the wafer W in an auxiliary manner. Furthermore, the heating lamp 130 may be provided in the center of the ceiling portion directly above the wafer W, and a gas introduction nozzle or the like may be inserted from the side wall of the container as the gas introduction portion 56 instead of the shower head portion 60. .

<Evaluation of Thin Film Formation Method of the Present Invention>
Next, since the copper film was formed using the thin film forming method of the present invention as described above, the evaluation result will be described.
FIG. 10 is a photomicrograph of the copper film deposited when the copper film forming step described in the first embodiment of the thin film forming method of the present invention is performed.
Here, as the semiconductor wafer W, a silicon substrate formed with an SiO ₂ film having a thickness of 100 nm as an insulating layer was used. In addition, copper acetate [Cu (CH ₃ COO) ₂ ] is used as a raw material organic acid copper, which is heated to 250 ° C. (T1), He gas is used as a carrier gas, and the substrate is heated to 300 ° C. (T2). The film was formed by heating. The process pressure is 200 mTorr, and the film formation time is 1 minute.

  As a result, as shown in FIG. 10, it can be confirmed that the copper film is formed on the entire substrate surface with a substantially uniform thickness, and that a high film formation rate of 200 to 300 nm / min can be obtained. It was.

<Second Embodiment of Film Forming Apparatus>
In the film forming apparatus shown in FIG. 2, a long gas passage 70 is extended from the shower head unit 60 and a raw material tank 72 is connected thereto. However, the present invention is not limited to this, and the second embodiment of the film forming apparatus shown in FIG. As described above, the raw material tank 72 may be disposed immediately above the shower head unit 60 and may be connected by a short gas passage 70 in which an on-off valve 71 is interposed in the middle. In FIG. 11, the same components as those shown in FIG. 2 are denoted by the same reference numerals and description thereof is omitted.

  Here, the case where copper acetate is used as an organic acid copper as a raw material has been described as an example. However, the present invention is not limited thereto. For example, the organic acid copper may be copper acetate, copper formate, copper propionate, 2-ethylhexene. One or more materials selected from the group consisting of acid copper can be used. In particular, as raw materials, organic acid copper having a carbonyl group, for example, anhydrous copper (II) acetate (sublimation temperature: about 200 ° C.), copper (II) formate tetrahydrate (sublimation temperature: about 60 ° C.), propionic acid Copper (II) monohydrate (sublimation temperature: about 100 ° C.) and copper (II) 2-ethylhexate (sublimation temperature: about 170 ° C.) are preferable. Of course, the temperatures T1, T2, and T3 described above are determined based on the sublimation temperature of each raw material.

  In the present embodiment, the case where acetic acid is used as the organic acid used when the copper film is etched is described as an example. However, the organic acid is not limited thereto, and the organic acid includes acetic acid, formic acid, One or two or more materials selected from the group consisting of propionic acid, valeric acid, oxalic acid, malonic acid, and 2-ethylhexanoic acid can be used. In addition, here, the concave portion 114 has been described as an example in which a single-stage groove-shaped or hole-shaped concave portion is embedded. However, the present invention is not limited to this. For example, the bottom of the groove-shaped concave portion is further provided with a hole-shaped concave portion. Of course, the present invention can also be applied to the case of embedding a recess having a two-stage structure in which is formed (this structure is also referred to as a dual damascene structure).

Furthermore, here, in each of the above embodiments, the case where the copper film forming step and the copper film removing step using an organic acid are performed in a reduced pressure (vacuum) atmosphere has been described as an example, but the present invention is not limited thereto. Instead, it may be carried out under a normal pressure atmosphere. Further, the film forming apparatus described here is merely an example, and it is needless to say that the film forming apparatus is not limited to this. For example, a thin mounting table 24 is used, and a heating lamp group is arranged as a heating means 26 below this. Alternatively, a film forming apparatus in which the wafer is heated may be used.
Although the semiconductor wafer is described as an example of the object to be processed here, the present invention is not limited thereto, and the present invention can be applied to a glass substrate, an LCD substrate, a ceramic substrate, and the like.

It is a schematic explanatory drawing which shows the fundamental film-forming apparatus for demonstrating the basic principle of the formation method of the thin film concerning this invention. It is a block diagram which shows 1st Example of the film-forming apparatus which concerns on this invention. It is a graph which shows the TG curve of copper acetate (anhydrous). It is process drawing for demonstrating the 1st Example of the formation method of a thin film. It is process drawing for demonstrating 2nd Example of the formation method of a thin film. It is process drawing for demonstrating the 3rd Example of the formation method of a thin film. It is a figure which shows the state at the time of sputtering the surface of a copper film. It is a flowchart which shows the 1st-3rd Example of the formation method of a thin film. It is a flowchart which shows the aspect of a copper film removal process. It is a microscope picture which shows the copper film deposited when the copper film formation process demonstrated in 1st Example of the formation method of the thin film of this invention was implemented. It is a block diagram which shows 2nd Example of the film-forming apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Film-forming apparatus 22 Processing container 24 Mounting stand 26 Heating means 48 Exhaust system 54 Exhaust pump 56 Gas introduction part 60 Shower head part 68 Raw material gas introduction means 72 Raw material tank 74 Organic acid copper 74A Copper acetate 76 Heating heater 98 High frequency generation source 100 Device control unit 102 Storage medium 110 Wiring layer 112 Insulating layer 114 Recess 116 Barrier layer 118 Copper film W Semiconductor wafer (object to be processed)

Claims (29)

In a method of forming a thin film on the surface of an object to be processed,
The organic acid copper is heated to a temperature T1 to form a gas, the gas is supplied onto the object to be processed maintained at a temperature T2 higher than the temperature T1, and a copper film is formed as the thin film on the surface of the object to be processed. A method for forming a thin film, comprising a step of forming a copper film. 2. The method of forming a thin film according to claim 1, wherein the temperature T1 is a temperature at which the organic acid copper is not decomposed. The method for forming a thin film according to claim 1 or 2, wherein the temperature T1 is 300 ° C or lower. 4. The method for forming a thin film according to claim 1, wherein an insulating layer is formed in advance on the surface of the object to be processed, and a recess is formed in the insulating layer. . The thin film forming method according to claim 4, wherein a barrier layer is formed in advance on the surface of the insulating layer including the surface in the recess. 6. The copper film removing step of exposing the surface of the barrier layer by scraping off a copper film other than the copper film formed in the concave portion after the copper film forming step. A method for forming a thin film according to 1. 7. The method for forming a thin film according to claim 6, wherein in the copper film removing step, an etching process using an organic acid is performed in a state where the object to be processed is maintained at a predetermined temperature T3. 8. The method of forming a thin film according to claim 7, wherein the relationship between the temperatures T2 and T3 is T2 ≦ T3, and each is 400 ° C. or less. 9. The method of forming a thin film according to claim 7, wherein in the copper film removing step, a plasma sputtering process for roughening a surface of the copper film is performed as a pre-process for the etching process. 10. The method of forming a thin film according to claim 9, wherein in the plasma sputtering process, an oxidizing gas that oxidizes the surface of the copper film is added. 7. The method of forming a thin film according to claim 6, wherein the copper film removing step performs chemical mechanical polishing (CMP). The thin film formation according to any one of claims 6 to 11, wherein a barrier layer removing step for removing the barrier layer exposed on the surface of the object to be processed is performed after the copper film removing step. Method. In a method of forming a thin film on the surface of an object to be processed,
An insulating layer forming step of forming an insulating layer on the surface of the object to be processed;
Forming a recess in the insulating layer;
A barrier layer forming step of forming a barrier layer on the surface of the insulating layer including the surface in the recess;
Removing a barrier layer other than the barrier layer formed on the surface in the recess to expose the underlying insulating layer; and
The surface of the object to be processed is irradiated with heating light, and the remaining barrier layer is selectively heated with respect to the exposed insulating layer and maintained at a predetermined temperature T2, and an organic acid copper is added. Forming a copper film as the thin film on the surface of the barrier layer while supplying the gas onto the object to be processed and filling the recess to fill the recess;
A method of forming a thin film, comprising: 14. The method of forming a thin film according to claim 13, wherein the temperature T1 is a temperature at which the organic acid copper is not decomposed. The method for forming a thin film according to claim 13 or 14, wherein the temperature T1 is 300 ° C or lower. 16. The method for forming a thin film according to claim 15, wherein a copper film removing step for removing an excess copper film is performed after the copper film forming step. 17. The method of forming a thin film according to claim 16, wherein the copper film removing step performs an etching process using an organic acid while maintaining the object to be processed at a predetermined temperature T3. 18. The method of forming a thin film according to claim 17, wherein the relationship between the temperatures T2 and T3 is T2 ≦ T3, and each is 400 ° C. or less. 19. The method for forming a thin film according to claim 17 or 18, wherein, in the copper film removing step, a plasma sputtering process for roughening a surface of the copper film is performed as a pre-process for the etching process. 20. The method of forming a thin film according to claim 19, wherein in the plasma sputtering process, an oxidizing gas that oxidizes the surface of the copper film is added. The method of forming a thin film according to claim 16, wherein the copper film removing step performs chemical mechanical polishing (CMP). The organic acid copper is made of one or more materials selected from the group consisting of copper acetate, copper formate, copper propionate, and copper 2-ethyl hexate, according to any one of claims 1 to 21. The thin film formation method as described. The organic acid is made of one or more materials selected from the group consisting of acetic acid, formic acid, propionic acid, valeric acid, oxalic acid, malonic acid, and 2-ethylhexic acid. The method for forming a thin film according to any one of the above. In a film forming apparatus for forming a thin film on the surface of an object to be processed,
A processing vessel made evacuable;
A mounting table for mounting the object to be processed;
Heating means for heating the object to be processed;
A gas introduction part provided in the processing container for introducing gas into the processing container;
Raw material gas supply means for supplying gaseous organic acid copper to the gas introduction part;
A device control unit for controlling the operation of the entire device,
A film forming apparatus, wherein a copper film is formed as the thin film on the surface of the object to be processed. 25. The film forming apparatus according to claim 24, wherein the heating means comprises a resistance heater provided on the mounting table. 25. The film forming apparatus according to claim 24, wherein the heating unit includes a heating lamp unit that emits light for heating. 27. The film forming apparatus according to claim 26, wherein the heating lamp unit emits light that can be selectively heated according to a material of a surface of the object to be processed. 28. The film forming apparatus according to claim 24, wherein the processing vessel is provided with plasma forming means for generating plasma. A processing vessel made evacuable;
A mounting table for mounting the object to be processed;
Heating means for heating the object to be processed;
A gas introduction part provided in the processing container for introducing gas into the processing container;
Raw material gas supply means for supplying gaseous organic acid copper to the gas introduction part;
When forming a thin film on the surface of the object to be processed using a film forming apparatus having an apparatus control unit that controls the operation of the entire apparatus,
The organic acid copper is heated to a temperature T1 to form a gas, the gas is supplied onto the object to be processed maintained at a temperature T2 higher than the temperature T1, and a copper film is formed as the thin film on the surface of the object to be processed. A storage medium for storing a program for controlling the film forming apparatus.

Images