JP2010189727A - FILM DEPOSITION METHOD FOR Cu FILM AND STORAGE MEDIUM - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film deposition method for Cu film by which the surface properties can be improved when a Cu film is deposited by a CVD process. <P>SOLUTION: When a Cu film is deposited on a wafer W by a CVD method which includes accommodating the wafer W being a substrate in a chamber, and then introducing a raw material for the deposition of the film containing a monovalent Cu-complex into the chamber in a gas phase state, an organic substance formed by the decomposition of the monovalent Cu-complex is introduced into the treatment vessel in a gas phase state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a Cu film forming method and a storage medium for forming a Cu film on a substrate such as a semiconductor substrate by CVD.

  In recent years, Cu having higher conductivity than Al and good electromigration resistance has attracted attention as a wiring material in response to the speeding up of semiconductor devices and the miniaturization of wiring patterns.

  As a Cu film forming method, a physical vapor deposition (PVD) method typified by sputtering has been frequently used. However, the defect that the step coverage is poor with the miniaturization of the wiring pattern has become apparent.

Therefore, as a method for forming a Cu film, there is a chemical vapor deposition (CVD) method in which Cu is formed on a substrate by a thermal decomposition reaction of a source gas containing Cu or a reduction reaction of the source gas with a reducing gas. It is being used. A Cu film formed by such a CVD method has high step coverage (step coverage) and is excellent in film formation in a long and narrow pattern, and is therefore suitable for forming a fine wiring pattern. .

  In forming a Cu film by this CVD method, a technique using a Cu complex such as hexafluoroacetylacetonate / trimethylvinylsilane copper (Cu (hfac) TMVS) as a film forming material (precursor) is known (for example, a patent). Reference 1). In particular, a monovalent Cu complex such as Cu (hfac) TMVS is suitable as a precursor because it has a relatively high vapor pressure and is easily vaporized.

Japanese Unexamined Patent Publication No. 7-48672

  However, although the monovalent Cu complex has a relatively high vapor pressure and is easily vaporized as described above, it has a low thermal stability, and thus may be decomposed in the gas phase before reaching the substrate to be processed. . For this reason, the deposition source gas itself is reduced, and the decomposition products are adsorbed on the substrate surface to inhibit the adsorption of the precursor, so that the initial nucleus density of Cu on the substrate surface is low and non-uniform. turn into. Moreover, the wettability of Cu will deteriorate by a decomposition product being taken in in a film | membrane. As a result, the morphology of the Cu film surface is deteriorated, resulting in a film having poor surface roughness.

This invention is made | formed in view of this situation, Comprising: When forming Cu film | membrane by CVD, it aims at providing the film-forming method of Cu film | membrane which can make surface property favorable.
It is another object of the present invention to provide a storage medium storing a program for executing such a film forming method.

  In order to solve the above-described problem, in the first aspect of the present invention, a substrate is accommodated in a processing container, and a film forming material containing a monovalent Cu complex is introduced into the processing container in a gas phase to perform CVD. In forming a Cu film on a substrate by the method, an organic substance produced by decomposition of the monovalent Cu complex is introduced into the processing vessel in a gas phase state. Provide a method.

  Thus, by introducing the organic substance produced by decomposing the monovalent Cu complex into the processing vessel in a gas phase state, the decomposition reaction in the gas phase is suppressed in the processing vessel. For this reason, in the processing container, a decrease in the amount of the monovalent Cu complex itself introduced into the processing container as a film forming raw material is suppressed, and the adsorption of the monovalent Cu complex on the substrate surface is inhibited by the decomposition product. And the initial nucleus density of Cu is improved, and the deterioration of the wettability of Cu due to the decomposition product being taken into the film is prevented. As a result, the morphology of the Cu film surface is improved, and a Cu film having good surface properties can be obtained.

  In the first aspect, an organic substance generated by decomposing the monovalent Cu complex is introduced into the processing container to form an atmosphere of the organic substance, and then the film is formed in the processing container. It is preferable to introduce raw materials. Thereby, decomposition | disassembly of the monovalent Cu complex introduced as a film-forming raw material more effectively can be suppressed.

  The monovalent Cu complex and the organic substance produced by the decomposition of the monovalent Cu complex can be introduced into the processing container separately. In addition, a vaporizer for vaporizing the monovalent Cu complex in liquid form and a carrier gas supply line for supplying a carrier gas to the vaporizer are provided, and the monovalent Cu complex is carrierized by a carrier gas to form a gas phase. The monovalent Cu complex is introduced into the processing vessel in a state, and an organic substance supply line for supplying an organic substance generated by decomposition of the monovalent Cu complex is connected to the carrier gas supply line. And the organic substance can be introduced into the processing container through the same line.

A β-diketone compound can be used as the monovalent Cu complex. Among them, hexafluoroacetylacetonate / trimethylvinylsilane copper (Cu (hfac) TMVS) can be mentioned as a suitable material. In this case, as the organic substance generated by decomposing the monovalent Cu complex, Trimethylvinylsilane (TMVS) is preferably used, and hexafluoroacetylacetonate copper (Cu (hfac) ₂ ) can also be used.

  According to a second aspect of the present invention, there is provided a storage medium that operates on a computer and stores a program for controlling a film forming apparatus, and the program is executed when the film forming method according to the first aspect is performed. A storage medium is provided that causes a computer to control the film formation apparatus.

  According to the present invention, the initial nucleus density of Cu is improved, and deterioration of the wettability of Cu due to incorporation of decomposition products into the film is prevented, so that the morphology of the Cu film surface is good and the surface properties are good. Cu film can be obtained.

1 is a schematic cross-sectional view showing an example of the configuration of a film forming apparatus that performs a film forming method of the present invention. It is a timing chart for demonstrating the film-forming method of Cu film | membrane in the film-forming apparatus of FIG. It is a schematic diagram for demonstrating the state in the chamber in the film-forming method of the conventional Cu film | membrane. It is a schematic diagram for demonstrating the state in the chamber in the film-forming method of Cu film | membrane of this invention. It is the schematic which shows the gas supply mechanism of the other film-forming apparatus which enforces the film-forming method of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Configuration of film forming apparatus for carrying out the film forming method of the present invention>
FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a film forming apparatus for carrying out the film forming method of the present invention.
The film forming apparatus 100 includes a substantially cylindrical chamber 1 that is airtightly configured, and a susceptor 2 for horizontally supporting a semiconductor wafer W that is a substrate to be processed is provided at the lower center of the chamber. It arrange | positions in the state supported by the provided cylindrical support member 3. As shown in FIG. The susceptor 2 is made of a ceramic such as AlN. Further, a heater 5 is embedded in the susceptor 2, and a heater power source 6 is connected to the heater 5. On the other hand, a thermocouple 7 is provided in the vicinity of the upper surface of the susceptor 2, and a signal of the thermocouple 7 is transmitted to the heater controller 8. The heater controller 8 transmits a command to the heater power supply 6 in accordance with a signal from the thermocouple 7, and controls the heating of the heater 5 to control the wafer W to a predetermined temperature.

A circular hole 1 b is formed in the top wall 1 a of the chamber 1, and a shower head 10 is fitted so as to protrude into the chamber 1 therefrom. The shower head 10 is for discharging a film-forming gas supplied from a gas supply mechanism 30 to be described later into the chamber 1. A first introduction path 11 into which hexafluoroacetylacetonate / trimethylvinylsilane copper (Cu (hfac) TMVS), which is a β-diketone compound, is introduced, and a second gas into which an atmosphere forming the atmosphere in the chamber 1 is introduced. And an introduction path 12. As a gas for forming this atmosphere, an organic substance generated by decomposing a monovalent Cu complex used as a film forming raw material is used. When the monovalent Cu complex used as a film forming raw material is Cu (hfac) TMVS, it is decomposed by heat to generate trimethylvinylsilane (TMVS) gas and hexafluoroacetylacetonate copper (Cu (hfac) ₂ ) gas. Therefore, these can be used as a gas for forming an atmosphere.

Inside the shower head 10, spaces 13 and 14 are provided in two upper and lower stages. A first introduction path 11 is connected to the upper space 13, and a first gas discharge path 15 extends from the space 13 to the bottom surface of the shower head 10. A second introduction path 12 is connected to the lower space 14, and a second gas discharge path 16 extends from the space 14 to the bottom surface of the shower head 10. That is, the shower head 10 can be uniformly formed in the spaces 13 and 14 without mixing the monovalent Cu complex gas as a film forming raw material and the organic material generated by decomposing the monovalent Cu complex forming the atmosphere. It is a postmix type that diffuses and discharges independently from the discharge passages 15 and 16.

  An exhaust chamber 21 that protrudes downward is provided on the bottom wall of the chamber 1. An exhaust pipe 22 is connected to the side surface of the exhaust chamber 21, and an exhaust device 23 having a vacuum pump, a pressure control valve, and the like is connected to the exhaust pipe 22. By operating the exhaust device 23, the inside of the chamber 1 can be depressurized to a predetermined degree of vacuum.

  On the side wall of the chamber 1, a loading / unloading port 24 for loading / unloading the wafer W to / from a wafer transfer chamber (not shown) and a gate valve G for opening / closing the loading / unloading port 24 are provided.

The gas supply mechanism 30 has a film forming material tank 31 that stores a monovalent Cu complex that is a film forming material, for example, Cu (hfac) TMVS that is a liquid β-diketone compound. As the monovalent Cu complex constituting the film forming raw material, other β-diketone compounds such as Cu (hfac) TEOVS (hexafluoroacetylacetone copper triethoxyvinylsilane) can be used. Also, CpCuTEP (cyclopentadienyltriethylphosphine copper) or the like can be used. When the monovalent Cu complex to be used is solid at room temperature, it can be stored in the film forming raw material tank 31 in a state dissolved in a solvent.

A pressure-feed gas pipe 32 for supplying a pressure-feed gas such as He gas is inserted into the film-forming raw material tank 31 from above, and a valve 33 is interposed in the pressure-feed gas pipe 32. In addition, a raw material delivery pipe 34 is inserted from above into the deposition raw material in the deposition raw material tank 31, and a vaporizer 37 is connected to the other end of the raw material delivery pipe 34. The raw material delivery pipe 43 is provided with a valve 35 and a liquid mass flow controller 36. Then, by introducing a pressurized gas into the film forming raw material tank 31 through the pressure supplying gas pipe 32, the monovalent Cu complex in the film forming raw material tank 31, for example, Cu (hfac) TMVS remains in a liquid state and is a vaporizer 37. To be supplied. The liquid supply amount at this time is controlled by the liquid mass flow controller 36. The vaporizer 37 is connected to a carrier gas pipe 38 for supplying Ar or H ₂ or the like as a carrier gas. The carrier gas pipe 38 is provided with two valves 40 sandwiching the mass flow controller 39 and the mass flow controller 39. The vaporizer 37 is connected to a film forming raw material gas supply pipe 41 that supplies the vaporized monovalent Cu complex toward the shower head 10. A film forming source gas supply pipe 41 is provided with a valve 42, and the other end is connected to the first introduction path 11 of the shower head 10. Then, the monovalent Cu complex vaporized by the vaporizer 37 is carried by the carrier gas, sent to the film forming raw material gas supply pipe 41, and supplied from the first introduction path 11 into the shower head 10. The vaporizer 37 and the film forming material gas supply pipe 41 are provided with a heater 43 for preventing the film forming material gas from condensing.

An atmosphere forming gas supply pipe 44 for supplying a gas for forming an atmosphere is connected to the second introduction path 12 of the shower head 10. A valve 45 is interposed in the atmosphere forming gas supply pipe 44. Then, an organic substance generated by decomposing a monovalent Cu complex used as a film forming raw material as an atmosphere forming gas is supplied from the second introduction path 12 into the shower head through the atmosphere forming gas supply pipe 44. The When the monovalent Cu complex used as the film forming raw material is Cu (hfac) TMVS, TMVS gas and Cu (hfac) ₂ gas can be used as described above. Among them, TMVS gas having a high vapor pressure is preferable.

  The film forming apparatus 100 includes a control unit 50, and the control unit 50 controls various components such as the heater power source 6, the exhaust device 23, the mass flow controllers 36 and 39, the valves 33, 35, 40, 42, and 45. The temperature control of the susceptor 2 is performed via the heater controller 8. The control unit 50 includes a process controller 51 including a microprocessor (computer), a user interface 52, and a storage unit 53. Each component of the film forming apparatus 100 is electrically connected to the process controller 51 and controlled. The user interface 52 is connected to the process controller 51, and a keyboard on which an operator inputs commands to manage each component of the film forming apparatus 100, and operating status of each component of the film forming apparatus 100. It consists of a display etc. that visualizes and displays. The storage unit 53 is also connected to the process controller 51, and the storage unit 53 corresponds to a control program for realizing various processes executed by the film forming apparatus 100 under the control of the process controller 51 and processing conditions. A control program for causing each component of the film forming apparatus 100 to execute a predetermined process, that is, a process recipe, various databases, and the like are stored. The processing recipe is stored in a storage medium (not shown) in the storage unit 53. The storage medium may be a fixed medium such as a hard disk or a portable medium such as a CDROM, DVD, or flash memory. Moreover, you may make it transmit a recipe suitably from another apparatus via a dedicated line, for example.

  Then, if necessary, a predetermined processing recipe is called from the storage unit 53 by an instruction from the user interface 52 and executed by the process controller 51, so that the film forming apparatus 100 can control the process controller 51. Desired processing is performed.

<Cu film forming method using the film forming apparatus of FIG. 1>
Next, a Cu film forming method using the film forming apparatus configured as described above will be described with reference to the timing chart of FIG. Here, a case where Cu (hfac) TMVS is used as a monovalent Cu complex as a film forming raw material and TMVS gas is used as an atmosphere forming gas is shown.

First, the gate valve G is opened, the wafer W is introduced into the chamber 1 by a transfer device (not shown), and placed on the susceptor 2. Next, the inside of the chamber 1 is evacuated by the exhaust device 23 so that the pressure in the chamber 1 is 13 to 1333 Pa (0.1 to 10 Torr), for example, 267 Pa (2 Torr), and the susceptor 2 is heated to 130 to 190 ° C. by the heater 5. 100 to 1000 in the chamber 1 through the carrier gas pipe 38, the vaporizer 37, the film forming raw material gas pipe 41, and the shower head 10.
The stabilization process of Step 1 is performed by supplying a carrier gas at a flow rate of mL / min (sccm), for example, 100 mL / min (sccm).

  When the stabilization of step 1 is performed for a predetermined time and the conditions are stabilized, the film forming process of step 2 is started. In the film forming process of Step 2, with the pressure in the chamber 1, the temperature of the susceptor 2 and the flow rate of the carrier gas maintained the same as in Step 1, first, TMVS gas is used as the atmosphere forming gas as the atmosphere forming gas supply pipe 44. Then, it is introduced into the chamber 1 through the shower head 10. The flow rate at this time is about 5 to 200 mL / min (sccm). When the inside of the chamber 1 becomes a TMVS gas atmosphere due to the introduction of the TMVS gas, Cu (hfac) TMVS is introduced as a film forming source gas. The flow rate at this time is about 50 to 500 mg / min as a liquid.

Cu (hfac) TMVS which is a film forming raw material is decomposed by a reaction shown in the following formula (1) on the wafer W which is a substrate to be processed heated by the heater 5 of the susceptor 2, and a predetermined film on the wafer W: For example, a Cu film is formed on the Ru film.
2Cu (hfac) TMVS → Cu + Cu (hfac) ₂ + 2TMVS (1)

By the way, Cu (hfac) TMVS, which is a monovalent Cu complex, is easily decomposed by heat. Therefore, when Ar gas or the like that is usually used as an atmosphere forming gas is used, the above reaction (1) occurs even in the gas phase. End. As shown in FIG. 3, while Cu (hfac) TMVS itself decreases, the decomposition product Cu (hfac) ₂ is adsorbed on the surface of the wafer W and inhibits the adsorption of Cu (hfac) TMVS as a film forming material. The density of the initial nucleus of Cu on the substrate surface is low and non-uniform. Moreover, the wettability of Cu will deteriorate by a decomposition product being taken in in a film | membrane. As a result, the morphology of the Cu film surface is deteriorated.

In contrast, in the present embodiment, as shown in FIG. 4, TMVS gas generated by decomposition of Cu (hfac) TMVS as a film forming raw material is introduced into the chamber 1, thereby In the phase, an atmosphere of TMVS on the right side of the above formula (1) is formed, so that the decomposition reaction of the above formula (1) is suppressed. For this reason, in the chamber 1, a decrease in the amount of Cu (hfac) TMVS itself that is a film forming raw material is suppressed, and the adsorption of Cu (hfac) TMVS on the surface of the wafer W is caused by Cu (hfac) ₂ that is a decomposition product. Inhibition is suppressed, the initial nucleus density of Cu on the surface of the wafer W is improved, and deterioration of the wettability of Cu due to incorporation of decomposition products into the film is prevented. As a result, the morphology of the Cu film surface is improved, and a Cu film having good surface properties can be obtained.

  After the Cu film having a predetermined thickness is formed in this way, the supply of Cu (hfac) TMVS, which is a film forming raw material gas, is stopped, and the supply of TMVS is continued for a predetermined time.

Then, after a predetermined time has elapsed, the purge process of Step 3 is performed. In the purge process of step 3, after stopping the TMVS, the vacuum pump of the exhaust device 23 is turned off, and the inside of the chamber 1 is purged by flowing the carrier gas into the chamber 1 as a purge gas. In this case, from the viewpoint of purging the inside of the chamber 1 as quickly as possible, it is preferable to supply the carrier gas intermittently as shown in FIG.

  After the purge step, which is the third step, is completed, the gate valve G is opened, and the wafer W is unloaded through the loading / unloading port 24 by a transfer device (not shown). Thus, a series of steps for one wafer W is completed.

As the atmosphere forming gas, Cu (hfac) ₂ produced by decomposition of another Cu (hfac) TMVS can be used instead of the TMVS gas. However, since Cu (hfac) ₂ has a vapor pressure lower than that of TMVS, it is likely to be slightly adsorbed on the wafer W, and the initial nucleus density of Cu tends to be lower than when TMVS gas is used.

  Even when another monovalent Cu complex as described above is used as a film forming source gas, decomposition in the gas phase is suppressed on the same principle, and the surface property of the formed Cu film is good. Can be. For example, when CpCuTEP (cyclopentadienyltriethylphosphine copper) is used as the monovalent Cu complex constituting the film forming material, TEP (triethylphosphine) is decomposed to form an atmosphere forming gas. As described above, by using this TEP (triethylphosphine), it is possible to suppress the decomposition of CpCuTEP (cyclopentadienyltriethylphosphine copper) which is a film forming raw material gas.

<Other film forming apparatus for carrying out the film forming method of the present invention>
Next, another film forming apparatus for carrying out the film forming method of the present invention will be described.
In this example, since the gas supply mechanism is mainly different from the film forming apparatus of FIG. 1, only the gas supply mechanism will be described. FIG. 5 is a schematic view showing a gas supply mechanism of another film forming apparatus for carrying out the film forming method of the present invention. As shown in FIG. 5, the gas supply mechanism 30 ′ includes an atmosphere forming gas supply pipe 44 that supplies an organic substance generated by decomposing a monovalent Cu complex used as a film forming raw material as an atmosphere forming gas into the shower head 10. 'Is connected to the carrier gas supply pipe 43. A valve 45 'is interposed in the atmosphere forming gas supply pipe 44'. Therefore, the atmosphere forming gas is supplied to the shower head via the film forming material gas supply pipe 41 that supplies the film forming material gas. In the case of this example, the film forming raw material gas and the atmosphere forming gas pass through the same pipe, and the shower head does not need to use the postmix type as shown in FIG. 1, and has one gas inlet and one diffusion space. Things can be used. By using such a gas supply mechanism 30 ′, decomposition of the film forming raw material gas in the vaporizer 37 and the film forming raw material gas supply pipe 41 can be suppressed as compared with the gas supply mechanism 30 of FIG. 1.

<Other applications of the present invention>
The present invention can be variously modified without being limited to the above embodiment. For example, in the above embodiment, an atmosphere of an organic substance generated by decomposition of a monovalent Cu complex during film formation is formed in the chamber, and then a film forming source gas is introduced into the chamber. Not limited to these, these may be introduced simultaneously. However, the effect of suppressing the decomposition of the monovalent Cu complex gas, which is the film forming raw material gas, is higher when the atmosphere of the organic substance formed by decomposing the monovalent Cu complex is formed first.

  In the above embodiment, the case where Cu (hfac) TMVS is mainly used as the monovalent Cu complex has been described. However, as described above, in principle, the same effect can be obtained with other monovalent Cu complexes. It is clear that is obtained.

  Furthermore, in the above-described embodiment, the liquid monovalent Cu complex is pumped and supplied to the vaporizer, and vaporized by the vaporizer. However, the present invention is not limited thereto, for example, vaporized by bubbling or the like, and the like. You may vaporize by another method.

  Furthermore, the film forming apparatus is not limited to the one in the above embodiment, and various apparatuses such as, for example, a mechanism that forms a plasma for promoting the decomposition of the film forming source gas can be used. .

Furthermore, although the case where the semiconductor wafer was used as a to-be-processed substrate was demonstrated, not only this but another board | substrate, such as a flat panel display (FPD) board | substrate, may be sufficient.

DESCRIPTION OF SYMBOLS 1; Chamber 2; Susceptor 3; Support member 5; Heater 10; Shower head 23; Exhaust device 30; Gas supply mechanism 31; Film formation raw material tank 34; Raw material delivery pipe 37; Film source gas supply piping 50; control unit 51; process controller 52; user interface 53; storage unit (storage medium)
W: Semiconductor wafer

Claims (9)

When a substrate is accommodated in a processing container, a film forming raw material containing a monovalent Cu complex is introduced into the processing container in a gas phase state, and a Cu film is formed on the substrate by a CVD method.
A method for forming a Cu film, comprising introducing an organic substance produced by decomposition of the monovalent Cu complex into the processing vessel in a gas phase.   An organic substance produced by decomposing the monovalent Cu complex is introduced into the processing container, and the atmosphere of the organic substance is set therein, and then the film forming material is introduced into the processing container. The method for forming a Cu film according to claim 1.   3. The Cu film according to claim 1, wherein the monovalent Cu complex and the organic substance generated by decomposing the monovalent Cu complex are separately introduced into the processing container. 4. The film forming method.   A vaporizer for vaporizing the monovalent Cu complex in a liquid state and a carrier gas supply line for supplying a carrier gas to the vaporizer are provided, and the monovalent Cu complex is carried by a carrier gas in a gas phase state. An organic substance supply line that supplies an organic substance that is generated by decomposing a monovalent Cu complex is connected to the carrier gas supply line so that the monovalent Cu complex and the monovalent Cu complex are introduced into the processing vessel. The method for forming a Cu film according to claim 1, wherein an organic substance is introduced into the processing container through the same line.   The method for forming a Cu film according to claim 1, wherein the monovalent Cu complex is a β-diketone compound.   6. The method of forming a Cu film according to claim 5, wherein the monovalent Cu complex is hexafluoroacetylacetonate / trimethylvinylsilane copper (Cu (hfac) TMVS).   The method for forming a Cu film according to claim 6, wherein the organic substance generated by decomposing the monovalent Cu complex is trimethylvinylsilane (TMVS). The method for forming a Cu film according to claim 6, wherein the organic substance generated by decomposing the monovalent Cu complex is hexafluoroacetylacetonate copper (Cu (hfac) ₂ ).   A storage medium that operates on a computer and stores a program for controlling a film forming apparatus, wherein the program performs the film forming method according to any one of claims 1 to 8 at the time of execution. And a computer that controls the film forming apparatus.

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