JP4543611B2 - Precoat layer forming method and film forming method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a precoat layer forming method and a film forming method for forming a precoat layer on the surface of a mounting table on which a semiconductor wafer or the like is mounted.
[0002]
[Prior art]
In general, in order to manufacture a semiconductor integrated circuit, a large number of desired elements are formed by repeatedly performing film formation and pattern etching on a silicon substrate such as a semiconductor wafer.
By the way, when forming the wiring connecting each element, the lower layer of the wiring layer for making electrical contact with each element is interdiffusion between the substrate Si and the contact metal and wiring material for obtaining the electrical contact resistance. Contact barrier metal is used for the purpose of suppressing or peeling from the underlayer, but as this contact barrier metal, not only has a low electrical resistance, but also a material with excellent corrosion resistance is used. Must be used. As a barrier metal material that can meet such a demand, in particular, a two-layer structure of a Ti film and a TiN film tends to be frequently used.
[0003]
In order to form a contact metal for a Ti film, TiCl is generally used._Four Gas and H₂ A Ti film having a desired thickness is formed by plasma CVD (Chemical Vapor Deposition) using a gas.
When performing the film forming process as described above, the surface of the mounting table on which the semiconductor wafer is mounted in the processing apparatus maintains the thermal in-plane uniformity of the wafer, and the metal element contained in the mounting table or the like In order to prevent metal contamination caused by the above, a precoat layer made of a TiN film is formed in advance. This precoat layer is removed after completion of film formation or whenever an unnecessary film in the film forming apparatus is cleaned. Therefore, when the film is cleaned, the precoat layer is pre-processed before film formation on the wafer. A precoat layer is deposited on the surface. Conventional techniques for forming such a precoat layer on a mounting table are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2001-144033 and 10-321558.
[0004]
[Patent Document 1]
JP 2001-144033 (paragraph numbers 0013-0020, FIGS. 1 and 2).
[Patent Document 2]
Japanese Patent Laid-Open No. 10-321558
[0005]
[Problems to be solved by the invention]
By the way, when depositing a thin film on the surface of a semiconductor wafer, one important point is how to suppress the generation of particles in order to improve the yield of the product wafer. However, as described above, when the precoat layer is formed on the surface of the mounting table, a very thin TiN film is deposited by CVD, and thereafter, the TiN film is plasma-nitrided for stabilization. In the method of forming the precoat layer by repeating this series of processes a plurality of times, for example, about 10 to 18 times, the used gas is frequently switched, so that the processing gas is contained in the shower head or the processing container. The replacement gas is not completely removed and the processing gas remains. In each case, a slight residual gas and a newly introduced processing gas are instantaneously mixed to form an unstable film, and the unstable film peels off and particles are generated more than necessary. There was a problem such as.
[0006]
In this case, since a series of processes of the TiN film forming process deposited by CVD and the plasma nitriding process of this TiN film are repeated, it takes a long time to form the entire TiN film to a desired thickness. However, this resulted in a significant decrease in throughput.
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 precoat layer forming method and a film forming method capable of suppressing generation of particles in a relatively short time.
[0007]
[Means for Solving the Problems]
As a result of intensive research on the formation method of the precoat layer in the processing container before the film formation process on the wafer, the present inventors have conducted a single thermal CVD film formation process without using plasma nitriding and repeated precoat formation. By forming a precoat layer having a desired thickness made of a TiN film, the present invention has been achieved by obtaining the knowledge that when a Ti film is formed on a substrate, the generation of particles can be greatly suppressed. Is.
[0008]
  The invention according to claim 1 is the surface of the mounting table in the processing apparatus in which a metal-containing film is formed on the surface of an object to be processed mounted on the mounting table in a processing container that can be evacuated. InProcess by thermal CVDIn the method of forming a recoat layer,In supplying a processing gas composed of a metal-containing gas and a reducing gas, the supply of the metal-containing gas is started prior to starting the supply of the reducing gas, and the supply of the metal is performed after the supply of the reducing gas is stopped. I will stop supplying gasThis is a method for forming a precoat layer.
  In this way, particles are generated by forming a stable precoat layer of a desired thickness made of a TiN film by a single thermal CVD film formation process without using repeated precoat layer formation and plasma nitridation stabilization. Can be greatly suppressed.
[0009]
  ThisFor example, as defined in claim 2As described above, the processing apparatus introduces the metal-containing gas and the reducing gas separately and discharges the gases separately into the processing container.Provided with a plurality of spaces partitioned for the purpose and radiation holes communicating with the spacesA shower head portion is provided, and the pressure of the gas containing the reducing gas in the shower head portion is set higher than the pressure of the gas containing the metal-containing gas.
  As described above, the pressure of the gas containing the reducing gas is set to be higher than the pressure of the gas containing the metal-containing gas in the shower head portion, so that the gas containing the metal-containing gas diffuses to the gas containing the reducing gas. It can be suppressed and generation of particles can be further suppressed.
[0010]
  For example, as defined in claim 3, the metal-containing gas is TiCl.₄ And the reducing gas is NH₃ Gas, and the precoat layer is made of a TiN film.
  For example, as defined in claim 4, the reducing gas contains H.₂ Gas is mixed. H like this₂ By adding gas, TiCl is reduced by the reducing power of hydrogen.₄ Is reduced and a stable film is formed, so that generation of particles can be further suppressed. Furthermore, the film quality is also improved.
  The related technology of the present invention is:A pre-coating layer is formed by thermal CVD on the surface of the mounting table in the processing apparatus in which a metal-containing film is formed on the surface of the object to be processed mounted on the mounting table in a processing container that can be evacuated. In supplying the processing gas comprising the metal-containing gas and the reducing gas into the processing container, the metal-containing gas is TiCl.₄ And the reducing gas is NH₃ Gas, H in the reducing gas₂ A method for forming a precoat layer is characterized in that a gas is added.
  in this case,For example,The processing apparatus includes a plurality of spaces partitioned for separately introducing the metal-containing gas and the reducing gas and separately discharging the gases into the processing container, and radiation holes communicating with the spaces. The shower head part is provided, and the pressure of the gas containing the reducing gas in the shower head part is set higher than the pressure of the gas containing the metal-containing gas.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a method for forming a precoat layer and a film forming method according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram showing a processing apparatus for carrying out the method of the present invention, and FIG. 2 is a partially enlarged sectional view showing a part of a shower head part. In this example, in order to form a metal-containing nitride film, TiCl is used as a metal-containing gas._Four Gas and NH as the reducing gas_Three A case where a TiN film is deposited using a gas will be described as an example.
[0012]
As shown in the figure, the processing apparatus 2 has a processing container 4 formed into a cylindrical shape by, for example, Al or an Al alloy material. The bottom portion 6 of the processing container 4 is formed in a concave shape at the center, and an exhaust port 8 for exhausting the atmosphere in the container is provided on the side wall of the recess. An exhaust system 12 having an intervening 10 is connected so that the inside of the processing container 4 can be uniformly evacuated from the periphery of the bottom.
[0013]
In the processing container 4, a disk-shaped mounting table 16 supported by a support column 14 standing from the bottom 6 is provided, and, for example, a semiconductor wafer W is mounted on the disk-shaped mounting table 16 as an object to be processed. It can be placed. Specifically, the mounting table 16 is made of, for example, ceramic such as AlN, and a resistance heater 18 is embedded therein as a heating means. The resistance heater 18 is connected to a power source 22 via a wiring 20 that passes through the column 14. Although not shown, the resistance heater 18 has a structure in which the plane is divided into a plurality of heating zones and can be controlled independently for each heating zone. Further, the mounting table 16 is provided with a pin hole 21 and a lift pin 23 which can be moved up and down. The lift pin 23 can be moved up and down when the wafer W is transferred. The lift pins 23 are moved up and down by an actuator 27 provided on the container bottom 6 via a bellows 25.
[0014]
Further, for example, a mesh-like lower electrode 24 is embedded in the vicinity of the upper surface of the mounting table 16, and the lower electrode 24 is grounded via the wiring 26 and the processing container 4. A precoat layer 28 that is a feature of the present invention is formed on the surface of the mounting table 16. In order to improve the thermal stability, the precoat layer 28 is preferably formed on all of the upper surface, the side surface, and the lower surface, but in the case of a film formation process in which film formation on the back surface side is difficult. Further, it may be formed only on the upper surface and the side surface, or may be formed only on the upper surface.
Here, the precoat layer 28 is made of the same film type as the film type to be formed on the semiconductor wafer W by this apparatus, that is, here, a TiN film deposited by one thermal CVD film forming process, and its thickness For example, the thickness is set to 0.4 μm or more.
[0015]
On the other hand, a shower head portion 30 is attached to the ceiling portion of the processing container 4 in an airtight manner with respect to the container side wall via an insulating member 32 as a gas introducing means for introducing a necessary processing gas. The shower head unit 30 is provided so as to face almost the entire upper surface of the mounting table 16, and a processing space S is formed between the shower head unit 30 and the mounting table 16. This shower head unit 30 introduces various gases into the processing space S in a shower shape, and the injection surface 34 on the lower surface of the shower head unit 30 has a large number of injection holes 36A and 36B for injecting gas. It is formed. In addition, the structure of this shower head part 30 can use the thing of the postmix structure which mixes for the first time in the process space S through separately flowing gas in the shower head part 30 depending on the kind of gas in the inside of the shower head part 30. . Here, a postmix structure is employed as described below. The shower head 30 is provided with a heater, and the shower head 30 is heated to a temperature of, for example, 200 to 600 ° C., preferably 400 to 600 ° C.
[0016]
The shower head 30 is divided into two spaces 30A and 30B. The spaces 30A and 30B are communicated with the injection holes 36A and 36B, respectively. Gas shower ports 38A and 38B for introducing respective gases into the spaces 30A and 30B in the head are provided above the shower head section 30, and gas is supplied to the gas feed ports 38A and 38B. The passages 40A and 40B are connected to each other. A plurality of branch pipes 42A and 42B are connected to the supply passages 40A and 40B, respectively.
[0017]
One branch pipe 42B has NH as a processing gas._Three NH storing gas_Three Gas source 44, H₂ H to store gas₂ Gas source 46, for example N as inert gas₂ N to store gas₂ A gas source 48 is connected to each of the other branch pipes 42A, and an Ar gas source 50 for storing, for example, Ar gas as an inert gas, and TiCl for film formation, for example._Four TiCl to store gas_Four Gas source 52, ClF as cleaning gas_Three ClF storing gas_Three Gas sources 51 are connected to each other. The flow rate of each gas is controlled by a flow rate controller provided in each branch pipe 42A, 42B, for example, a mass flow controller 54. Each gas is introduced by opening and closing a valve 55 provided in each branch pipe 42A, 42B. In the illustrated example, each gas at the time of film formation is supplied in a mixed state in one supply passage 40A, 40B. However, the present invention is not limited to this, and some or all of the gases are individually different. You may make it use what is called postmix gas conveyance form which supplies in a channel | path and mixes in the shower head part 30 or the process space S. FIG.
[0018]
The actual shower head portion 30 is attached with a plurality of block bodies formed by cutting out an aluminum plate or the like, for example, a block body A and a block body B as shown in FIG. However, due to surface contact, gas may slightly diffuse from one to the other through a slight gap 54 between the joints of both block bodies A and B, but in the present invention this will be described later. Even in this case, generation of particles can be suppressed.
[0019]
Further, a plasma high frequency power source 56 of, eg, 450 kHz is connected to the shower head unit 30 via a wiring 58 as a plasma generating means so as to function as an upper electrode. A matching circuit 60 that performs impedance matching and a switch 62 that cuts off high frequency are sequentially provided in the middle of the wiring 58. In this case, if the processing is performed without cutting off the high frequency and generating plasma, it functions as a thermal CVD apparatus. A gate valve 64 that is opened and closed when a wafer is carried in and out is provided on the side wall of the processing container 4. A lift pin for lifting the wafer is provided below the mounting table 16, and a guide ring or a focus ring is provided on the outer periphery of the mounting table 16. In addition, here, only a main portion of each gas supply system is shown as an example. For example, a plurality of Ar gas supply systems are provided, which can be independently supplied into the processing vessel. TiCl_Four Various gases including the gas are provided with an exhaust line (not shown) or the like that can be discarded directly into the exhaust system 12 without passing through the processing container 4.
[0020]
Next, a method of forming the precoat layer 28 performed using the processing apparatus configured as described above will be described with reference to FIG. FIG. 3 is a time chart for explaining each step of the precoat layer, and FIG. 4 shows a main part of supply timing (modes 1 to 4) of main gases into the processing vessel in the precoat thermal CVD film forming process. It is a timing chart. First, a description will be given with reference to FIG.
First, the semiconductor wafer W is not placed on the mounting table 16 in the processing container 4 and the processing container 4 is sealed. The inside of the processing container 4 is, for example, in a maintained state (by parts replacement or the like) or in a previous process, all unnecessary films have been removed by the cleaning process. Therefore, the surface of the mounting table 16 is precoated. There is no layer, and the material of the mounting table 16 is exposed.
[0021]
Next, the method for forming a precoat layer of the present invention is carried out. In other words, in the present invention, a precoat layer 28 is obtained by forming a TiN film having a desired thickness in a single precoat thermal CVD film forming step.
Specifically, four aspects of the method for forming the precoat layer will be described here.
[0022]
<Aspect 1: Formed by thermal CVD for pre-coating once (see FIG. 4A)>
First, a case where the precoat layer is formed by one precoat thermal CVD will be described.
Step 1: First, heat up of the processing apparatus is started.
Step 2: Start evacuation in the processing container 4.
Step 3: Ar gas and N while evacuating the inside of the processing vessel 4₂ The supply of gas is started and the inside of the processing container 4 is purged. At this time, the flow rate of Ar gas is in the range of 10 to 5000 sccm, N₂ The gas flow rate is in the range of 10 to 5000 sccm. Then, step 2 and step 3 are repeated 72 times, for example.
Step 4: The mounting table 16 is heated to a predetermined process temperature, for example, 500 to 700 ° C. by the resistance heater 18.
Step 5: The gas remaining in each flow controller is caused to flow directly to the exhaust system 12 through the exhaust line (not shown) without passing through the processing vessel 4 and discarded.
Step 6: Ar gas and N in the state that the evacuation in the processing container 4 is continued₂ The supply of gas is stopped and the inside of the processing container 4 is evacuated.
Through the above steps 1 to 6, the operation for optimally adjusting the film forming environment in the processing container 4 is completed.
[0023]
Step 7: Next, into the processing container 4, NH_Three Gas and N₂ Gas and Ar gas are respectively supplied, and the inside thereof is maintained at a predetermined pressure, for example, about 40 to 666.5 Pa, so that the supply amount of each gas is stabilized. NH at this time_Three Gas supply is in the range of 10-5000sccm, N₂ The gas supply amount is in the range of 10 to 5000 sccm, and the Ar gas supply amount is in the range of 10 to 5000 sccm.
Step 8: Next NH_Three Gas and N₂ While supplying the gas and Ar gas into the processing vessel 4, further TiCl_Four Start supplying gas. In this case, TiCl_Four The gas is not introduced into the processing vessel 4 but directly flows to the exhaust system 12 through the exhaust line and discarded._Four Stabilize the gas flow rate (flow controller operation). This process is performed for about 10 seconds, for example.
[0024]
Step 9: Next NH_Three Gas, N₂ While supplying the gas and Ar gas into the processing vessel 4, the valve is switched to TiCl_Four A gas is supplied into the processing container 4 to perform a single precoat forming process to form a precoat layer. The processing time at this time is set, for example, to a time during which the film thickness of the precoat layer can be formed to about 0.5 μm, for example, about 2000 seconds.
Step 10: Next, TiCl_Four Gas and NH_Three Stop supplying gas, Ar gas and N₂ The gas continues to flow and is continuously evacuated, and the residual gas in the processing container 4 is removed for a predetermined time, for example, about 10 seconds.
Step 11: Next TiCl_Four Gas and NH_Three The supply of all the gases is stopped by stopping the supply with the gas, and the residual gas in the processing container 4 is eliminated by continuing the evacuation. In this way, the precoat process is completed, and a stable precoat film is formed.
[0025]
<Aspect 2: TiCl_Four Gas advance (see FIG. 4B)>
Next, TiCl_Four A case where the precoat layer is formed by first applying the gas will be described.
The operation for optimally adjusting the film forming environment in the processing container 4 from Step 1 to Step 6 is the same as in the case of the first embodiment.
Step 7: Next N₂ Gas and Ar gas are supplied into the processing container 4 and the inside of the processing container 4 is stabilized to a predetermined pressure, for example, about 40 to 666.5 Pa. At the same time, TiCl_Four A gas is flowed, and the gas flow rate is stabilized by directly discarding the gas into the exhaust system 12 via the exhaust line without supplying the gas into the processing container 4.
At this time, N₂ The gas flow rate ranges from 10 to 5000 sccm, the Ar gas flow rate ranges from 10 to 5000 sccm, TiCl_Four The gas flow rate is in the range of 2 to 500 sccm.
Step 8: Next, N₂ While continuously supplying the gas and Ar gas into the processing container 4, the valve is switched to TiCl_Four Gas is also supplied into the processing container 4 and preflow (first out) is performed. This advance is performed only for a predetermined time T1, for example, 10 seconds.
This TiCl_Four By the advance gas, the inside of the processing container 4 is TiCl._Four The partial pressure of this gas is raised in the atmosphere to suppress the generation of particles.
[0026]
Step 9: Next, N₂ Gas, Ar gas and TiCl_Four While supplying gas into the processing vessel 4, NH_Three A gas is supplied into the processing container 4 and a precoat forming process is performed once to form a precoat layer. This processing time is set, for example, to a time during which the film thickness of the precoat layer can be formed to about 0.5 μm, for example, about 2000 seconds. NH at this time_Three The gas flow rate is, for example, in the range of 10 to 1000 sccm.
Step 10: Next, NH_Three Stop supply of gas, TiCl_Four Gas, Ar gas, and N₂ Continue to supply the gas into the processing container 4 and TiCl_Four After the gas is flowed, the inside of the processing vessel 4 is TiCl_Four Use a gas atmosphere. This processing time is about 20 seconds, for example.
Step 11: Next, Ar gas and N₂ The gas supply continues and TiCl_Four The supply of gas is stopped and the residual gas in the processing container 4 is exhausted. This processing time is about 20 seconds, for example.
Step 12: Next, Ar gas and N₂ The supply of all gases is stopped by stopping the supply of gas, and the residual gas in the processing container 4 is eliminated by continuing the evacuation. In this way, the precoat process is completed, and a stable precoat film is formed.
[0027]
<Aspect 3: H₂ Addition of gas (see FIG. 4C)>
Next, H₂ A case where a precoat layer is formed by adding a gas will be described.
The operation for optimally adjusting the film forming environment in the processing container 4 from Step 1 to Step 6 is the same as in the case of the first embodiment.
Step 7: Next, NH_Three Gas and H₂ Gas and Ar gas are supplied into the processing container 4 and the inside of the processing container 4 is stabilized to a predetermined pressure, for example, about 40 to 666.5 Pa.
Step 8: Next, NH_Three Gas and H₂ While supplying gas and Ar gas into the processing vessel 4, TiCl_Four A gas is flowed, and the gas flow rate is stabilized by discarding the gas into the exhaust system 12 via an exhaust line without supplying the gas into the processing container 4. H at this time₂ The flow rate of the gas is in the range of 10 to 5000 sccm, and the flow rates of the other gases are the same as those in step 7 of aspect 2.
[0028]
Step 9: Next NH_Three Gas and H₂ While supplying gas and Ar gas into the processing vessel 4, the valve is switched to TiCl_Four Gas is also supplied into the processing container 4, and a precoat forming process is performed once to form a precoat layer. This processing time is set, for example, to a time during which the film thickness of the precoat layer can be formed to about 0.5 μm, for example, about 2000 seconds.
Step 10: Next, TiCl_Four Gas and NH_Three Stop gas supply, H₂ The supply of the gas and Ar gas into the processing container 4 is continued, and the residual gas in the processing container 4 is exhausted. This processing time is about 20 seconds, for example.
Step 11: Next, H₂ The supply of all gases is stopped by stopping the supply of gas and Ar gas, and the residual gas in the processing container 4 is eliminated by continuing the evacuation. In this way, the precoat process is completed, and a stable precoat film is formed.
[0029]
<Aspect 4: TiCl_Four Gas advance and H₂ Addition of gas (see FIG. 4D)>
Next, TiCl_Four Advance gas and H₂ A case where a precoat layer is formed by adding a gas will be described.
The operation for optimally adjusting the film forming environment in the processing container 4 from Step 1 to Step 6 is the same as in the case of the first embodiment.
Step 7: Next H₂ Gas and Ar gas are supplied into the processing container 4 and the inside of the processing container 4 is stabilized to a predetermined pressure, for example, about 40 to 666.5 Pa. At the same time, TiCl_Four A gas is flowed, and the gas flow rate is stabilized by directly discarding the gas into the exhaust system 12 via the exhaust line without supplying the gas into the processing container 4.
At this time, H₂ The gas flow rate ranges from 10 to 5000 sccm, the Ar gas flow rate ranges from 10 to 5000 sccm, TiCl_Four The gas flow rate is in the range of 2 to 500 sccm.
Step 8: Next, H₂ While continuously supplying the gas and Ar gas into the processing container 4, the valve is switched to TiCl_Four Gas is also supplied into the processing container 4 and preflow (first out) is performed. This advance is performed only for a predetermined time T1, for example, 10 seconds.
This TiCl_Four By the advance gas, the inside of the processing container 4 is TiCl._Four The partial pressure of this gas is raised in the atmosphere to suppress the generation of particles.
[0030]
Step 9: Next, H₂ Gas, Ar gas and TiCl_Four While supplying gas into the processing vessel 4, NH_Three A gas is supplied into the processing container 4 and a precoat forming process is performed once to form a precoat layer. This processing time is set, for example, to a time during which the film thickness of the precoat layer can be formed to about 0.5 μm, for example, about 2000 seconds. NH at this time_Three The gas flow rate is, for example, in the range of 10 to 1000 sccm.
Step 10: Next, NH_Three Stop supply of gas, TiCl_Four Gas, Ar gas, and H₂ Continue to supply the gas into the processing container 4 and TiCl_Four After the gas is flowed, the inside of the processing vessel 4 is TiCl_Four Use a gas atmosphere. Thereby, a rapid reaction is suppressed. This processing time is about 20 seconds, for example.
Step 11: Next, Ar gas and H₂ The gas supply continues and TiCl_Four The supply of gas is stopped and the residual gas in the processing container 4 is exhausted. This processing time is about 20 seconds, for example.
Step 12: Next, Ar gas and H₂ The supply of all gases is stopped by stopping the supply of gas, and the residual gas in the processing container 4 is eliminated by continuing the evacuation. In this way, the precoat process is completed, and a stable precoat film is formed.
[0031]
Thereby, a TiN film for forming the precoat layer 28 is stably deposited on the surface of the mounting table 16 by thermal CVD without using plasma. At this time, the switch 62 is in an OFF state, and the high frequency voltage is of course not applied to the shower head unit 30.
[0032]
In this way, the TiN film formation process by thermal CVD is performed for a predetermined time, and the precoat layer 28 having a predetermined film thickness, for example, 0.4 μm or more (in the case of each of the above embodiments 1 to 4, 0.5 μm) is formed. If obtained, the precoat thermal CVD film forming step is completed as described above. At the end of this film forming step, the NH_Three After the gas flow is stopped and the supply of this gas is stopped, after a predetermined time T2 has elapsed, TiCl_Four The gas supply may be stopped (modes 2 and 4). Here, the predetermined times T1 and T2 are about 1 second and 30 seconds, respectively, preferably 10 to 20 seconds.
When the pre-coating process is completed in this way, a Ti film forming process is performed on each product wafer one by one. As is well known, for example, TiCl is formed on the product wafer._Four A film forming step of forming a Ti film having a desired thickness using plasma CVD while flowing a gas, and the Ti film is formed using NH with or without using plasma._Three Gas and H₂ A Ti film is realized by nitriding in the presence of gas.
[0033]
Next, the pre-coating layer 28 formed as described above is formed, and the particle generation state when 50 product wafers are actually processed in the processing apparatus 2 is evaluated. The evaluation result will be described. For comparison, a conventional precoat layer was also evaluated.
FIG. 5 is a graph showing the relationship between the number of processed product wafers and the number of particles.
In FIG. 5, a straight line X represents a pre-coating layer according to a conventional method. Here, for example, one cycle of processing comprising a Ti film forming step by plasma CVD and a nitriding step of nitriding the Ti film to form a TiN film is performed. By performing 18 cycles, a precoat layer having a thickness of about 0.5 μm was obtained. The straight line A shows the precoat layer formed by the gas supply method of the previous aspect 1, the straight line B shows the precoat layer formed by the gas supply method of the previous aspect 2, and the straight line C shows the gas of the gas of the previous aspect 3. The precoat layer formed by the supply method is shown, and the straight line D shows the precoat layer formed by the gas supply method of the previous embodiment 4. Particles having a size of 0.2 μm or more were detected.
[0034]
In the case of the pre-coating layer according to the conventional method indicated by the straight line X, the number of particles is about 20 until the number of wafers is about 25, and the number of particles decreases to several only when the number of wafers is 50. The result is unfavorable.
On the other hand, in the case of the present invention shown by the straight lines A to D, the number of particles is 10 or less in the entire period up to 50 wafers except for the first part of the aspect 1, and good results are obtained. It turned out to be obtained. In particular, TiCl_Four In the case of the straight lines B and D where the gas is first discharged, the number of particles is approximately several over the entire range up to 50 wafers, and it has been found that particularly good results are obtained.
In addition, in the conventional method for forming a precoat layer, it takes about 43 minutes to form this, but in the method for forming a precoat layer of the present invention, the time can be shortened to about 33 minutes. However, when considering only the film thickness on the mounting table, this time is considered to require several times this time to create the same state during the process.
[0035]
Next, a description will be given of the point that generation of particles can be suppressed when a precoat layer is formed by the method of the present invention. First, FIG. 6 shows NH_Three TiCl when the flow rate is constant_Four It is a graph which shows the general relationship between the flow volume of gas, and the film-forming rate of a TiN film | membrane. According to this graph, NH_Three Slightly TiCl in the gas_Four When the gas is supplied, the film formation rate increases rapidly, and this rapid increase is caused by TiCl._Four It continues until the gas flow rate reaches a certain level, and when the film formation rate peaks at the point P1, thereafter TiCl_Four As the gas increases, the film formation rate decreases rapidly, and thereafter the film formation rate stabilizes and gradually decreases. As a process condition for forming a general TiN film, an area where the film formation rate is stable, for example, the area A1 is used in consideration of the controllability of the film thickness.
[0036]
However, the deposition gas TiCl_Four NH of gas and plasma nitriding_Three When the gas supply is switched over many times, particularly in the case of the precoat layer forming method according to the conventional method, TiCl_Four Supply and stop of gas (when Ti film is formed by plasma CVD), NH_Three Since the gas supply and its stop (when nitriding the Ti film) are alternately repeated, the immediately preceding processing gas remains in the processing vessel 4 each time, so that TiCl in particular._Four NH remaining in the container at the start of gas supply_Three Trace amounts of TiCl in the gas_Four The region A2 condition of supplying gas occurs.
The film generated in this area A2 tends to float in the processing space S as particles. Accordingly, as shown in the straight lines A to D in FIG._Four Gas and NH_Three When there is no switching of supply with gas, it becomes possible to suppress generation | occurrence | production of a particle significantly as mentioned above.
[0037]
In particular, as shown in FIG._Three TiCl before the start of gas supply_Four Start gas supply, NH_Three TiCl after gas supply stop_Four By stopping the gas supply (see line B in FIG. 5), a large amount of TiCl is flowing._Four NH in the gas_Three Since gas flows in, the process conditions for generating particles in the region A2 in FIG. 6 are suppressed, and a stable TiN film is formed. Therefore, even if the Ti film is formed on the wafer, the particles Can be further prevented.
Further, when the supply of both gases is started or stopped at the same time, the process condition of the region A2 may occur with a slight timing error. Both gases are preferably supplied.
[0038]
  Further, as described above, there is a slight gap 45 or the like as shown in FIG. 2 in the shower head unit 30, and the film forming gas may slightly leak from one space to the other space. Even in this caseIn FIG. 6 aboveIn order to prevent the process conditions in the region A2 from occurring, NH is preferable.₃ The pressure of the space 30B through which the gas flows is changed to TiCl₄ For example, it is preferable to set the pressure higher about 13330 Pa than the pressure in the space 30A through which the gas flows. As a result, the generation of the process conditions in the above-described region A2 is prevented.₃ TiCl from the gas side₄ Even if intrusion (leakage) occurs in the gas side, TiCl₄ NH from gas₃ Since the occurrence of intrusion (leakage) into the gas can be suppressed, the generation of particles can be suppressed.
[0039]
Furthermore, NH increases pressure._Three H in the gas side₂ By adding a gas (aspects 3 and 4), NH_Three Gas is TiCl_Four When leaking to the gas side, NH_Three H is much smaller in molecule than gas₂ Since gas diffuses preferentially, NH_Three Gas diffusion leakage is suppressed, and generation of particles can be further suppressed.
In addition, as a result of continuous processing on the product wafer, in the case of the method of the present invention, in aspects 1 to 4, the in-plane and inter-surface uniformity of the film thickness and specific resistance is good, and good process repeatability It turned out to be obtained.
[0040]
In the above embodiment, only the TiN film was formed by thermal CVD as the pre-coating thermal CVD film forming process, but the present invention is not limited to this, and the surface of the TiN film is stabilized as shown in FIG. In order to achieve this, nitriding treatment using plasma or without using plasma may be performed. Further, as shown in FIG. 3C, after the TiN film is formed by thermal CVD, a Ti film forming step by plasma CVD and a nitriding step for nitriding this Ti film are each performed once, and a precoat layer is formed. You may make it stabilize the surface of.
It should be noted that the process conditions such as gas flow rate, pressure, and temperature described in this embodiment are merely examples, and of course are not limited thereto. Similarly, the structure of the processing apparatus is merely an example. For example, the frequency of the plasma high-frequency power source 56 may be other than 450 kHz, and microwaves may be used as the plasma generating means. Good.
[0041]
Further, here, the case where a TiN film is formed has been described as an example. However, the present invention is not limited to this. A metal film such as tungsten (W) or a metal-containing nitride film such as tungsten silicide (WSix) or tantalum oxide (TaOx) is used. Of course, the present invention can also be applied to the film formation.
Furthermore, the size of the semiconductor wafer can be any of 6 inches (150 mm), 8 inches (200 mm), and 12 inches (300 mm).
Further, the present invention can be applied not only to a resistance heater but also to an apparatus using lamp heating as a heating means. Furthermore, the object to be processed is not limited to a semiconductor wafer, and can be applied to a glass substrate, an LCD substrate, and the like.
[0042]
【The invention's effect】
  As described above, according to the precoat layer forming method and film forming method of the present invention, the following excellent operational effects can be exhibited.
  According to the present inventionFor example, the generation of particles can be greatly suppressed by forming a precoat layer having a desired thickness made of a TiN film by a single thermal CVD film forming process without using plasma.
  In addition, since the supply of both gases is not started or stopped simultaneously, the process conditions for generating particles are suppressed, and as a result, the generation of particles can be further prevented.
Especially according to claim 2According to the invention, since the pressure of the gas containing the reducing gas is set higher than the pressure of the gas containing the metal-containing gas in the shower head portion, the gas containing the metal-containing gas is placed on the gas side containing the reducing gas. Leakage can be prevented and generation of particles can be further suppressed.
  In particular,According to claim 3According to the invention, H₂ By adding gas, generation of particles can be further suppressed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a processing apparatus for carrying out a method of the present invention.
FIG. 2 is a partial enlarged cross-sectional view showing a part of a shower head portion.
FIG. 3 is a time chart for explaining each step of the precoat layer.
FIG. 4 is a timing chart showing the main part of the timing (modes 1 to 4) of supply of main gases into the processing container in the precoat thermal CVD film forming step.
FIG. 5 is a graph showing the relationship between the number of processed product wafers and the number of particles.
FIG. 6 NH_Three TiCl when the flow rate is constant_Four It is a graph which shows the general relationship between the flow volume of gas, and the film-forming rate of a TiN film | membrane.
[Explanation of symbols]
2 processing equipment
4 processing containers
16 Mounting table
18 Resistance heater (heating means)
28 Precoat layer
30 Shower head (gas introduction means)
56 High frequency power supply for plasma (plasma generating means)
W Semiconductor wafer (object to be processed)

Claims (5)

A pre-coating layer is formed by thermal CVD on the surface of the mounting table in the processing apparatus in which a metal-containing film is formed on the surface of the object to be processed mounted on the mounting table in a processing container that can be evacuated. In the way to
In supplying a processing gas composed of a metal-containing gas and a reducing gas into the processing container, the supply of the metal-containing gas is started and the supply of the reducing gas is stopped prior to starting the supply of the reducing gas. The method for forming a precoat layer is characterized in that the supply of the metal-containing gas is stopped after. The processing apparatus includes a plurality of spaces partitioned for separately introducing the metal-containing gas and the reducing gas and separately discharging the gases into the processing container, and radiation holes communicating with the spaces. the has a shower head provided with the pressure of the gas containing the reducing gas in the shower head unit, claims, characterized in that it is set higher than the pressure of the gas containing the metal-containing gas 2. A method for forming a precoat layer according to 1 . The metal-containing gas is TiCl ₄ gas, the reducing gas is NH ₃ gas, the pre-coat layer forming method according to claim 1 or 2 pre-coat layer of, wherein the of TiN film. The method for forming a precoat layer according to any one of claims 1 to 3, wherein H ₂ gas is mixed in the reducing gas. Forming a pre-coat layer to claim 1乃Optimum 4, whichever is the surface on the mounting table by the method for forming the precoat layer as described in paragraph (1)
Thereafter, placing the object to be processed on the mounting table and forming a metal-containing film on the surface of the object to be processed;
A film forming method comprising:

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