TW201114942A - Film forming method and plasma film forming apparatus - Google Patents

Abstract

A film depositing method and a plasma film apparatus are provided to exhale the air inside the treatment container to be vacuum from periphery by including a pressure control valve and a vacuum pump. A bottom part(24) of the treatment basin(22) is formed with an exhaust pipe(26) for discharging the air within the container. The exhaust pipe is connected with a vacuum exhausting system(28). The vacuum exhausting system comprises a ventilating passage(29) connected to the exhaust pipe.

Description

[Technical Field] The present invention relates to a film forming method and a plasma film forming apparatus, and particularly to a method of forming a film such as a barrier layer on a surface of a workpiece such as a conductor wafer, and a plasma. Film forming device. [Prior Art] Generally, in order to manufacture a semiconductor device, a desired process such as a film formation process, an etching process, an annealing process, and an oxidative diffusion process is repeated for a semiconductor wafer. In addition, in the middle of the semiconductor device manufacturing process, the wiring material or the embedding material is mainly made of the (A1) alloy. However, the line width and the aperture are increasingly finer, and the speed is desirably increased. Therefore, tungsten (W) is used. Or a copper (Cu) or the like, and when the metal material such as Al, W, or Cu is used as a buried material for wiring or contact holes, for example, an insulating material such as a tantalum oxide film or the like For example, the purpose of preventing diffusion, or improving the adhesion of the film, or improving the adhesion between the conductive layer of the lower layer electrode or the wiring layer that is in contact with the hole is performed. A boundary portion between the above insulating layer or the lower layer. Further, the barrier layer is widely known as a Ta film, a TaN film, or a TiN film (Patent Document No. 5). This point is illustrated in Figure 13. 13 is a bottom electric isoelectric layer of a production aluminum working tendency material SiO 2 在 which is formed by semi-film formation when a concave portion on a surface of a semiconductor wafer is buried, and a Ti reference film formation method. Drawings. As shown in FIG. 13(A), a conductive layer 2 serving as a wiring layer or the like is formed on the surface of the semiconductor wafer W composed of, for example, a germanium substrate or the like, so that the conductive layer 2 can be covered in the semiconductor layer. The entire surface of the wafer W is formed with an insulating layer 4 made of, for example, a SiO 2 film or the like at a predetermined thickness. The above-mentioned conductive layer 2 is composed of, for example, a germanium layer doped with impurities, and specifically, an electrode corresponding to a transistor or a capacitor, in particular, a contact with a transistor by NiSi (nickel telluride) ) formed. Further, the insulating layer 4 is formed with a recess 6 for contact such as a through hole or a via hole for electrically contacting the conductive layer 2. Further, the recessed portion 6 may have an elongated groove (groove). The surface on which the above-mentioned conductive layer 2 is formed is exposed to the bottom of the recessed portion 6. Further, in order to form a barrier layer having the above-described function on the entire surface of the semiconductor wafer W including the bottom surface and the side surface in the concave portion 6, that is, on the surface of the insulating layer 4 and the surface of the conductive layer 2, as shown in FIG. B), the entire surface (inner surface) in the recessed portion 6 is also included, and the Ti film 8 is formed on the entire surface of the wafer, for example, on the TL film 8, as shown in FIG. 13(C). The TiN film is formed of a barrier layer I2 composed of a two-layer structure of the Ti film 8 and the TiN film 10 described above. Then, in order to stabilize the TiN film 10, it is heated in an NH3 atmosphere, thereby applying a nitriding treatment. Further, when the TiN film 10 is not formed, the barrier layer I2 is formed only by the Ti film 8. The Ti film 8 is formed, for example, by a sputtering film forming process or a CVD (Chemical Vapor Deposition) method using, for example, a thermal CVD method or alternating by using a TiC 14 gas or the like. Flow-6- 0 201114942 The SQ (Sequential Flow Deposition) method of the moving material gas and the nitriding gas is formed. When the barrier layer 12 is formed, the conductive material such as tungsten is buried in the recessed portion 6, and then etched, etc. In the case of the above-mentioned Japanese Patent Laid-Open No. Hei. No. Hei. No. Hei. No. 2004-232080 (Patent Document 3) [Patent Document 5] Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. The formation method has not caused much problem in the past when the line width or the hole diameter is not so strict. However, as the progress of miniaturization progresses, once the line width or the aperture is formed smaller, the design basis becomes stricter. Produce it In other words, as described above, for example, in order to form a film, a film formation process is performed by a plasma CVD method. However, at this time, a reducing gas such as H 2 gas is supplied in a large amount with respect to a material gas such as TiC14 gas. However, when the line width or the hole diameter is small and the aspect ratio is also increased, it is difficult for the material gas to sufficiently penetrate into the concave portion 6, and the step coverage is lowered. As a result, the stack 201114942 is accumulated at the bottom of the concave portion 6. Or the film thickness of the Ti film on the side wall in the concave portion is insufficient, and in particular, if the film thickness of the Ti film deposited on the bottom portion is insufficient, there is a possibility that the contact resistance increases. For example, in FIG. 13(B), the crystal is deposited on the crystal. The film thickness H1 of the Ti film 8 on the surface of the circle W is sufficiently thick, and the film thickness H2 of the Ti film 8 deposited on the bottom surface in the concave portion 6 is extremely thin, and the step coverage is lowered. When the hole diameter of the concave portion described above is formed to be 60 nm or less, the above-described irregularity is more remarkable, and there is a problem that the step coverage is largely lowered. Moreover, such a problem is not only in the Ti film. In the film formation, the TiN film is formed in the same manner as in the film formation. The present invention has been made in view of the above problems, and is intended to be effectively solved by the creator. It is an object of the present invention to provide a The inner diameter or the width of the concave portion on the surface of the treated body becomes small, or the aspect ratio of the concave portion becomes large, and the film forming method and the plasma processing apparatus which can improve the step coverage at the time of film formation of the film can be obtained. (Means for Solving the Problem) The inventors of the present invention have focused on the film formation results of the Ti film or the TiN film by the plasma CVD method, and have found that the reaction can be a source gas by the reaction at the time of film formation. The flow rate of each gas is set in a state in which the reaction rate is limited, and the step coverage can be improved to achieve the present invention. In the film forming method of the invention of claim 1, the insulating layer having the concave portion is housed in the object to be processed formed on the surface, and the raw material gas and the reducing gas containing titanium are supplied into the processing container. ,borrow

-8, 201114942 A film forming method for forming a titanium-containing film on the object to be processed by a plasma CVD method, wherein the reaction can be a reaction state of the reaction rate of the source gas. In this manner, the respective flow rates of the source gas and the reducing gas are set. In the film forming method, the insulating layer having the concave portion is housed in the object to be processed formed on the surface, and the raw material gas containing titanium and the reducing gas are supplied into the processing container by plasma processing. In the CVD method, a film formation method for forming a titanium-containing film on a target object is set such that the respective flow rates of the material gas and the reducing gas are set so that the reaction can be a reaction state of the reaction rate of the source gas. Even if the inner diameter or the width of the concave portion formed on the surface of the object to be processed becomes small, or the aspect ratio of the concave portion becomes large, the step coverage at the time of film formation of the film can be improved. The invention of claim 2 is the invention of claim i, wherein the raw material gas is a gas containing gas, and the reducing gas of BII is a chlorine-containing gas. According to the invention of claim 2, the ratio of the ratio of the number of chlorine atoms in the environment in the processing container to the number of atoms of hydrogen in the range of 0.5 to 1.5 can be set. The respective flow rates of the source gas and the reducing gas. According to the invention of claim 2, in the invention of claim 2, the Cl/Η ratio of the ratio of the number of chlorine atoms in the environment in the processing container to the number of atoms of hydrogen can be in the range of 〇·7 to 1.3. The flow rate of each of the raw material gas and the reducing gas is set. The invention of claim 5 is the invention of any one of claims 1 to 4, wherein a nitriding gas is supplied into the processing container. The invention of claim 6 is the invention of claim 5, wherein the nitriding gas is nitrogen. The invention of claim 7 is the invention according to any one of claims 1 to 6, wherein the inner diameter or the width of the concave portion is 6 Onm or less. According to the invention of any one of claims 1 to 7, the material gas is TiCl4 gas, and the reducing gas is Η2 gas. The plasma processing apparatus according to the invention of claim 9 is a plasma processing apparatus for forming a titanium-containing film on an object to be processed formed on a surface of an insulating layer having a concave portion, and is characterized in that: a mounting table that mounts the object to be processed in the processing container and has a function as a lower electrode; a heating means that heats the object to be processed; and a gas introduction means that is inserted into the processing container Introducing various gases necessary for the source gas and having a function as an upper electrode; a gas supply means for supplying the various gases to the gas introduction means; and a plasma forming means for the stage and the gas introduction means A plasma forming method is formed between the first and second embodiments of the present invention, and the control unit is controlled to perform the film forming method according to any one of claims 1 to 8. The memory medium of the invention of claim 10 is a program that can be read in a computer that controls the plasma processing apparatus, and when a plasma processing apparatus is used to form a film containing titanium -10, 201114942 on the surface of the object to be processed. The film forming method according to any one of claims 1 to 7, wherein the plasma processing apparatus includes: a processing container that can be evacuated; and a mounting table that is attached to the processing container The insulating layer having the concave portion is placed on the object to be processed formed on the surface, and has a function as a lower electrode, a heating means for heating the object to be processed, and a gas introduction means for introducing the inside of the processing container Each of the gases necessary for the material gas has a function as an upper electrode; the gas supply means supplies the various gases to the gas introduction means; and the plasma forming means is disposed between the mounting table and the gas introduction means Forming a plasma; and a control unit, which is a control unit as a whole. [Effect of the Invention] According to the film forming method and the plasma film forming apparatus of the present invention, the second advantageous effect can be exhibited. In the film forming method, the insulating layer having the concave portion is accommodated in the treatment container capable of being evacuated, and the object to be treated formed on the surface is supplied, and the raw material gas and the reducing gas containing titanium are supplied into the processing container by plasma CVD. A method for forming a film of a titanium-containing film on a target to be treated by a method in which a reaction can be a reaction state of a reaction rate of a material gas

S -11 - 201114942 The flow rate of the material gas and the reducing gas is set. Therefore, even if the inner diameter or the width of the concave portion formed on the surface of the object to be processed becomes small, or the aspect ratio of the concave portion becomes large, film formation can be performed as it is. The step coverage is increased. [Embodiment] Hereinafter, a preferred embodiment of the film forming method and the plasma processing apparatus of the present invention will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic block diagram showing an example of a plasma processing apparatus for carrying out the method of the present invention. As shown in the figure, the plasma processing apparatus 20 of the present invention has a processing container 22 having a cylindrical shape, for example, made of an alloy, a stainless steel, or the like, and the processing container 22 is grounded. The bottom portion 24 of the processing vessel 22 is provided with an exhaust port 26 for discharging the environment within the container, where the exhaust port 26 is connected to the vacuum exhaust system 28. The vacuum exhaust system 28 has an exhaust passage 29 connected to the exhaust port 26, and in the exhaust passage 29, pressure from which the valve opening degree can be adjusted for pressure adjustment is sequentially provided from the upstream side to the downstream side thereof. The valve 30 and the vacuum pump 32 are adjusted. Thereby, the inside of the processing container 22 can be uniformly evacuated by the bottom peripheral portion. In the processing container 2 2, a disk-shaped mounting table 36 is provided via a post 34 made of a conductive material, and a semiconductor wafer W such as a substrate or the like can be placed thereon. Specifically, the mounting table 36 is made of a ceramic such as A1N, and the surface thereof is coated with a conductive material, and serves as a lower electrode of the electrode for plasma, and the lower electrode is grounded. A semiconductor wafer W having a diameter of, for example, 300 mm can be placed on the mounting table 36. Further, a case where a mesh-shaped conductive member is buried in the mounting table 36 as the lower electrode may be used. -12-201114942 A heating means 38, which is made of, for example, a resistance heating heater, is embedded in the mounting table 36 to heat the semiconductor wafer W while maintaining the temperature at a desired temperature. Further, the mounting table 36 is provided with a positioning device (not shown) that presses the peripheral portion of the semiconductor wafer W and is fixed to the mounting table 36, or pushes up the semiconductor wafer W when the semiconductor wafer W is carried in and out. The lift pin (not shown) that lifts and lowers. A shower head 4' as a gas introduction means is provided on the top of the processing container 22, and serves as the other upper electrode of the electrode for plasma. The shower head 40 is formed integrally with the top plate 42. Further, the peripheral portion of the top plate 42 is airtightly attached to the upper end portion of the container side wall via the insulating member 44. The shower head 4 is formed of a conductive material such as aluminum or aluminum alloy. The shower head 40 is formed in a circular shape so as to be disposed opposite to the upper surface of the mounting table 36 so as to be substantially opposite to the mounting table. A processing space S is formed between 36. The shower head 40 is a person who introduces various gases into the treatment space S in a shower form, and a plurality of injection holes 46 for injecting a gas are formed on the injection surface below the shower head 40. Further, a gas introduction port 48 for introducing a gas into the head is provided in the upper portion of the shower head 4, and a gas supply means 50 for supplying various gases is attached to the gas introduction port 48. This gas supply means 50 has a supply passage 52 which is connected to the above-described gas introduction port 48. Here, the supply passage 52 connects a plurality of branch pipes 54. The manifolds 54 are respectively connected:

a TiCU gas source 56 for storing a raw material gas containing titanium for film formation, such as TiCl 4 gas;

S -13- 201114942 H2 gas source 58' is in the form of a reducing gas such as H2 gas;

The Ar gas source 60' is configured to store a prize gas or a diluent gas such as an Ar gas; the NH3 gas source 62' is a nitriding gas such as ammonia; and the N2 gas source 64' is stored in a purge gas, etc. & gas. In addition, N2 gas is sometimes used as the nitriding gas. Further, the flow rate of each gas is controlled by a flow controller 66 such as a mass flow controller provided in each branch pipe 54. Further, on the upstream side and the downstream side of the flow controller 66 of each of the branch pipes 514, an on-off valve 68 for stopping the supply and supply of the respective gases is provided as needed. In addition, although it is shown that the supply gas is supplied to one supply passage 52 in the mixed state, the present invention is not limited thereto, and a part of the gas or all of the gas may be separately supplied to the different supply passages. The shower head 40 is mixed. Further, it is possible to mix the gases in the gas transporting form of the processing space S (so-called post-mixing) without mixing them in the supply path 52 or in the shower head 40 depending on the type of gas supplied. Further, an annular insulating member 69 made of, for example, quartz or the like is provided between the outer periphery of the shower head 4A in the processing container 22 and the inner wall of the processing container 22, and the lower surface thereof is set to be the shower head 40. The same level of the spray surface, the formation of plasma will not be biased. Further, a head heating heater 72 is provided on the upper surface side of the shower head 40 to adjust the shower head 4 to a desired temperature. Further, the processing container 22 has a plasma forming means 74 for forming a plasma in the processing space S between the mounting table 36 and the shower head 4A. Specifically, the plasma forming means 74 has a wire 76 connected to the upper portion -14, 201114942 of the shower head 40, and the wire 76 is connected to the plasma generating power source of, for example, 4500 kHz via the matching circuit 78 on the way. High frequency power supply 70. Here, the high-frequency power source 70 is variable in output power, and is capable of outputting electric power of an arbitrary size. Further, an opening 79 through the wafer W is formed in the side wall of the processing container 22, and the opening 79 is provided with a gate valve 80 that can be hermetically opened and closed when the semiconductor wafer W is carried in and out. Further, in order to control the overall operation of the plasma processing apparatus 20, for example, a control unit 82 including a computer or the like can provide an instruction for controlling the process pressure, the process temperature, and the supply amount of each gas, and includes a high frequency. Power on/off indication of power supply, etc. Further, the control unit 82 has a memory medium 84 for storing a computer program necessary for the above control. This memory medium 84 is composed of, for example, a floppy disk, a CD (Compact Disc), a hard disk, a flash memory, or a DVD. [Explanation of Film Forming Method] Next, a film forming method of the present invention which is carried out using the plasma processing apparatus configured as described above will be described with reference to Figs. 1 to 3 . 2 is a view showing an example of a state of the upper surface of the object to be processed when the film forming process is performed on the semiconductor wafer, and FIG. 3 is a view for explaining an optimum range of the respective flow rates of the material gas and the reducing gas in the method of the present invention. chart. Here, the titanium-containing film formed by the plasma treatment method is exemplified as a Ti (titanium) film, but the process conditions described herein are as described later, and the TiN film formed by the plasma treatment method ( When a titanium nitride film is formed, it can apply similarly similarly. First, on the mounting table 36 of the processing container 22, for example, the diameter is

S -15- 201114942 3 0 0mm semiconductor wafer W. The film formation state on the upper surface of the semiconductor wafer W is, for example, as shown in Fig. 2(A), and a concave portion 6 is formed on the surface of the wafer W. The structure of this semiconductor wafer W is the same as that described in Fig. 13(A). In other words, a conductive layer 2 such as a wiring layer is formed on the surface of the semiconductor wafer W, and a Si 2 film or the like is formed on the entire surface of the semiconductor wafer W so as to cover the conductive layer 2 with a predetermined thickness. The insulating layer 4 is formed. The above-mentioned conductive layer 2 is composed of, for example, a germanium layer doped with impurities, and specifically, an electrode corresponding to a transistor or a capacitor, particularly when contacting a transistor, by Ni S i (nickel) Further, the insulating layer 4 is formed with a recess 6 for contact such as a through hole or a via hole for electrically contacting the conductive layer 2 in the insulating layer 4. The inner diameter of the concave portion 6 (the concave portion 6 is the groove width) is, for example, 60 nm or less, and the aspect ratio (ratio of the depth of the concave portion to the hole diameter) is about 10 to 20 degrees. Further, the recessed portion 6 may have an elongated groove (groove). The surface on which the above-mentioned conductive layer 2 is formed is exposed to the bottom of the recessed portion 6. Further, a barrier layer having the above-described function is formed on the entire surface of the semiconductor wafer W including the bottom surface and the side surface in the concave portion 6, that is, on the surface of the insulating layer 4 and the surface of the conductive layer 2. First, the TiCl 4 gas of the titanium-containing source gas and the Ar gas of the reducing gas and the Ar gas of the plasma gas (dilution gas) are respectively flown from the gas supply means 50 to the shower head 40 of the gas introduction means at a predetermined flow rate. The respective gases are introduced into the processing container 22 from the shower head 40, and the inside of the processing container 22 is evacuated by a vacuum pump 32 of the vacuum exhaust system 28 by -16, 2011, and is maintained at a predetermined pressure. At the same time, 'the high frequency power source 70 of the plasma forming means 74 applies a high frequency of 450 kHz to the shower head 4 of the upper electrode, and a high frequency electric field is applied between the shower head 4 and the mounting table 36 as the lower electrode. Put in electricity. Thereby, the Ar gas is plasmated' to react the TiCi4 gas with the helium gas. On the surface of the semiconductor wafer W, as shown in Fig. 2(B), the film is formed by plasma CVD (Chemical Vapor) Deposition) method to form a film. The temperature of the semiconductor wafer W is maintained by heating at a predetermined temperature by a heating means 38 composed of a resistance heating heater embedded in the mounting table 36. Thereby, not only the upper surface of the semiconductor wafer W but also the bottom surface or the side surface in the concave portion 6 is deposited with the Ti film 8. In this case, in the method of the present invention, the respective flow rates of the source gas and the reducing gas are set such that the reaction at the time of film formation can be a reaction state of the reaction rate of the source gas. Thereby, not only the upper surface of the semiconductor wafer W but also the bottom surface or the side surface in the recessed portion 6 is deposited with the Ti film 8. In other words, as in the case of the conventional film formation method, a flow rate of a raw material gas (TiCl 4 gas), for example, 12 SCCm, for example, a flow rate of, for example, 4,000 sccm of a reducing gas (H 2 gas) is supplied, and the reaction state of the supply gas is limited. To perform film formation processing. The reason why such a large amount of reducing gas is supplied is because there is a fear that the number of C 1 atoms which cause deterioration of film characteristics remains in the deposited film. When the film formation process is performed in a reaction state in which the supply gas is supplied at a rate limit, when the TiCl gas reaches the upper surface of the wafer w, it immediately reacts with a large amount of H2 gas, and it is easy to deposit a film on the upper surface side of the wafer W.

S -17- 201114942

The TiCl4 gas is consumed on the upper surface of the wafer W, and it is difficult for the TiCl4 gas to intrude into the concave portion. As a result, it is difficult for the film to be deposited on the bottom surface or the side wall in the concave portion, and it is conceivable that the step coverage is lowered. On the other hand, as in the present invention, the flow rate of the H 2 gas of the reducing gas is greatly reduced as compared with the conventional film forming method, and the film forming process is performed in the reaction state of the reaction rate of the source gas as described above. Since the presence of the H2 gas is small, there is no phenomenon in which the Tic 14 gas is exhausted only in the upper portion of the wafer W, and as a result, the Tic 14 gas easily enters the inside of the concave portion 6. As a result, the bottom surface or the side wall in the recessed portion 6 is also sufficiently deposited with the film, and the step coverage can be improved. In the method of the present invention, as shown in FIG. 3, the process conditions for the flow rates of the material gas and the reducing gas are as shown in the graph showing the relationship between the flow rate of the TiC 14 gas on the horizontal axis and the flow rate of the H 2 gas on the vertical axis. The area indicated by the diagonal line below L1. Further, the straight line L 1 is a straight line connecting the points A1 and A2 in FIG. 3 as will be described later, and when the coordinates are (TiCl4 gas flow rate seek and H2 gas flow rate seek), A1 is (12, 50), and A2 is ( 2 0, 1 0 0 ). The region below the straight line L1 is a region in a reaction state in which the reaction rate of the source gas is determined as described later. It is preferable that the atomic ratio of the number of C1 atoms to the number of germanium atoms of the supplied TiCl4 gas and H2 gas, that is, a straight line L2 with a Cl/Η ratio of "1.5" and a straight line with a Cl/Η ratio of "0.5" The region surrounded by L3 is more preferably a region surrounded by a straight line L4 having a Cl/Η ratio of "1.3" and a straight line L5 having a Cl/Η ratio of "0, 7". This will be described later. Further, the process temperature and the process pressure are the same as those of the conventional film formation method -18-201114942, and the process temperature is, for example, in the range of 400 to 700 t, and the process pressure is, for example, in the range of 133 to 1333 Pa. [Explanation of Process for Optimal Proportion of Process Conditions] Next, a procedure for obtaining an optimum range of process conditions such as the chart shown in Fig. 3 will be described. 4 is a graph showing the relationship between the H2 flow rate and the film formation rate in the conventional film formation method in which the H2 flow rate is very large, and FIG. 5 is a graph showing the relationship between the H2 flow rate and the film formation rate when the H2 flow rate is very small, and FIG. 6 is an enlarged view of FIG. A part of the graph is displayed to expand the film formation rate to form a peak near the peak to display the graph. Fig. 7 is a graph showing the relationship between the flow rate of TiCl4 and the film formation rate when various H2 flow rates are changed, and Fig. 8 is a graph showing the relationship between the atomic ratio of chlorine to hydrogen (Cl/Η ratio) and the film formation rate when various H2 flow rates are changed. The film forming process for the Ti film described later is a plasma processing apparatus as described with reference to Fig. 1 . First, the relationship between the H2 flow rate and the film formation rate was verified for the conventional film formation method when the Ti film was first formed. Regarding the process conditions at this time, the conventional film formation method is to reduce the C1 concentration in the film and to supply a large amount of the flow rate of the H2 gas with respect to the flow rate of the Tic 14 gas, where the Tic 14 gas is 1 2 s ccm. The relative flow rate of the Η 2 gas is changed in the range of 500 to 4 0 0 sc cm. Further, the flow rate of the Ar gas of the plasma gas was set to 1600 seem °, and the process pressure was set to 667 Pa ', the process temperature was 550 ° c', and the high-frequency power was 800 watts (W), and the film formation time was 30 sec. The film thickness measurement here is not the bottom surface in the concave portion of the wafer but is deposited on the wafer.

S -19- 201114942 The thickness of the film on the surface, which is the same as the film formation rate shown in the following chart. As shown in Fig. 4, it is known that the film formation rate increases substantially linearly in proportion to the increase in the flow rate of H2. In this way, the film formation reaction occurs in the vicinity of the upper surface of the wafer due to the flow rate of the TiCl 4 gas, under the condition that the H 2 gas is supplied in a large amount, because the film formation reaction of the Ti film is a reaction-limiting reaction for forming a TiCl 4 gas. The TiCl4 gas is then consumed. Therefore, the amount of TiCl4 gas that has entered the concave portion such as the hole is extremely small. As a result, the thickness of the Ti film deposited on the bottom surface or the side wall of the concave portion with respect to the surface of the wafer is extremely thin, and the step coverage becomes variable. difference. Therefore, the film formation rate of the region where the flow rate of H2 gas is very small is reviewed in comparison with the conventional film formation method. Here, the process temperature, the process pressure, the film formation time, and the high frequency power are the same as those shown in Fig. 4, respectively. Further, the flow rate of 1 gas (14 gas) was set to 2 types of 12 sccm and 20 sccm, and the flow rate of 112 gas was changed within a range of 30 to 500 sccm (Ar = 2000 sccm). The results at this time are shown in Fig. 5 and 6. As shown in Fig. 5 and Fig. 6, it is confirmed that the film formation rate is such that a peak is generated in a flow rate field in which the flow rate of the H2 gas is extremely small, for example, a flow rate of 50 to 100 seem. This peak is a flow rate of 12 sccm of TiCl4. When the flow rate of H2 is 50 sccm, the flow rate of H2 is 20 sccm, and the flow rate of H2 is point A2 at 100 pm. That is, it is known that the film formation rate increases with H2 from a state where the flow rate of H2 is small to a peak position. The flow rate increases sharply, and after passing through the peak position, even if the flow rate increases, the film formation rate tends to decrease substantially or slightly. The reason is because the peak position is 201114942 in FIGS. 5 and 6. It is a reaction zone in which the flow rate of the TiCl4 gas is limited, and the area where the flow rate of the TiCl4 gas is lower than the peak position is the area where the flow rate of the H2 is smaller than the peak position. The area of the reaction rate limit. The point A 1 in Fig. 6 corresponds to the point A1 in Fig. 3, and the point A2 in Fig. 6 corresponds to the point A2 in Fig. 3. Next, the dependence of the film formation rate on the flow rate of the TiCl4 gas is performed. This is to verify the relationship between the flow rate of TiCl4 gas and the film formation rate while changing the flow rate of various H2 gases. The process conditions, process temperature, process pressure, film formation time, and high frequency power are respectively shown in Figure 4. The same is true for the case where the flow rate of the H2 gas is set to 3 〇SCCm, 40 sccm, 50 sccm (Ar is 2000 sccm in any case) and the standard 4000 sccm (Ar=1600 sccm) of the conventional method, and the flow rate of the TiCl4 gas is changed. In the range of 4 to 20 sccin, the results at this time are shown in Fig. 7 and Fig. 8. Fig. 8 is the result shown in Fig. 7, and the horizontal axis is used to rewrite the atomic ratio of each gas flow rate of TiCl4 and H2 (Cl/ Here, for example, "Cl/Η ratio = 1" is a relationship of "TiCl4 flow rate / H2 flow rate = 1/2" when converted to a flow ratio of TiCl4 and H2. As shown in Figs. 7 and 8 The case of the "standard (H2: 4000 sccm)" of the conventional film formation method is shown. It can be seen that as the flow rate of the TiCl4 gas is increased, the film formation rate is linearly increased. This is because the entire gas supply amount becomes a reaction state of the supply rate limit of the TiCl4 gas. In contrast, the H2 gas flow rate is 30 to 50 sccm. At this time, the film formation rate gradually increases as the flow rate of the TiC 14 gas increases, and becomes a peak enthalpy when the gas flow rate is about 12 to 2 Os ccm, and then gradually decreases. In addition, H2 gas flow

When the amount of S - 21 - 201114942 is 40 sccm and 50 sccm, although it is not shown in the graph, it is conceivable that the film formation rate is lowered after the peak after the peak of the graph when the flow rate of H 2 gas is 30 sccm. In this case, the case shown in Fig. 7 is that the peak position depends on the gas flow rate of 112, and each moves slightly in the left-right direction (the flow direction of the Tici4 gas), but as shown in Fig. 8, the Cl/Η ratio is plotted on the horizontal axis. In the middle, regardless of the flow rate of the H 2 gas, the position where the Cl/Η ratio is approximately "1" becomes a peak, and thus gradually decreases as the region in the right direction travels. Here, "C1" indicates the total number of C1 atoms contained in the flow rate of the TiCl4 gas at the time of film formation, and "H" indicates the total number of atoms contained in the flow rate of the H2 gas at the time of film formation. Further, Cl/Η ratio = 1 is the flow ratio of TiCI4 to Η2 as described above, "TiCl4 flow rate / Η2 flow rate" = "1/2". Thus, in Fig. 7, only when the gas flow rate of Η2 is small (30 to 50 sccm), the peak of the film formation rate is generated with respect to the flow rate of TiCl4, and the conventional film formation method of the H2 gas flow rate is above the wafer. In the vicinity of the TiCl4 gas, the amount of TiCl4 gas intruding into the concave portion such as the contact hole is reduced. On the other hand, even when the flow rate of the H2 gas is small, in a region where the flow rate of the TiCl4 gas is small, TiCl4 gas is consumed in the vicinity of the upper surface of the wafer, but in the vicinity of the film formation rate, there is a peak region in the wafer W. In the vicinity of the upper surface, there may be TiCl4 gas remaining without exhausting the TiCl4 gas. Therefore, the remaining TiCl4 gas may intrude into the concave portion to form a film, and improvement in step coverage may be expected. Further, in the plasma at the time of film formation, the C1 atom due to TiCl4 and the η atom due to the H2 gas are liquefied as HC1 (gas), but in Fig. 8, the film formation rate is in the Cl/Η ratio. = about 1 is a peak 値, which means -22- 201114942. In order to reduce one Cl atom, one ruthenium atom is required, and the film formation reaction is carried out in the amount of ruthenium atoms of the C1 atom which occurs when the film formation is just removed. It will become the reaction speed limit area, and the step coverage will also be better. Therefore, as described above, it is understood that the respective flow rates of the material gas and the reducing gas are set to be particularly good as "c 1 / Η ratio = 1" in a reaction state in which the reaction rate of the Tic 14 gas (feed gas) can be set. The improved step coverage is satisfactory nearby. In this case, the Cl/Η ratio in the environment in the treatment vessel is preferably in the range of 0.5 to 1.5, more preferably in the range of 〇.7 to 1.3, and once it is out of the above range, the film formation rate is apparent from Fig. 8. Will be lower, so it is not ideal. Therefore, as described above with reference to Fig. 3, the process conditions of the source gas and the reducing gas are in a region lower than the straight line L1 in Fig. 3, that is, a region in which the reaction rate of the source gas is in a reaction state, It is desirable that the ratio of the number of C1 atoms to the atomic number of η atoms of the supplied TiCU gas and the Η2 gas, that is, the line L2 whose Cl/Η ratio is "1.5" and the line L3 whose ratio of Cl/Η is "0.5" is L3. The area enclosed is more preferably a region surrounded by a straight line L4 having a ci/h ratio of "Κ3" and a straight line L5 having a Cl/Η ratio of "0.7". Here, the point Ρ1 in FIGS. 7 and 8 corresponds to the point Ρ1 in FIG. 3, and the point Ρ2 in FIGS. 7 and 8 corresponds to the point Ρ 2 in FIG. As described above, the flow rate of the helium gas of the reducing gas is greatly reduced as compared with the conventional film forming method, and the film forming process is performed in the reaction state of the reaction rate of the source gas as described above. Since the presence of 1 gas is small, the phenomenon that the TiCl4 gas is depleted only in the vicinity of the upper surface of the wafer W is lost, and as a result, the TiCU gas is easily invaded.

S -23- 201114942 The inside of the recess 6. As a result, the bottom surface or the side wall in the recessed portion 6 is also sufficiently deposited with the film, and the step coverage can be improved. [Evaluation of the actual film formation process] Next, the film formation process of the Ti film is actually performed by the conventional film formation method and the film formation method of the present invention on the semiconductor wafer W composed of the tantalum substrate, and the evaluation thereof is described. result. The process conditions at the time of film formation, in the conventional film formation method, the process temperature was 550 ° C, the process pressure was 667 Pa, and TiCl4/Ar/H2 = 12/160 0/4 000 SCCm for each gas flow rate. The input high-frequency power is 800 W, and the film formation time is 30 s e c °. In the case of the method of the present invention, the point P2 in Figs. 3, 7 and 8 is representative. That is, the process temperature is 550 ° C, and the process pressure is 667 Pa '. The gas flow rate is TiCl4 / Ar / H2 = 20 / 2000 / 40 sccm. The input high-frequency power was 800 W, and the film formation time was 30 sec. That is, only the flow rate of the TiCl4 gas and the H2 gas is different with respect to the conventional film formation method. Further, the diameter of the hole-shaped concave portion formed on the ruthenium substrate is 60 nm, and the aspect ratio is 10 °. FIG. 9 is a graph showing the measurement of the film thickness at each position in the concave portion, and FIG. 1 is a schematic display of the concave portion. The measurement of the film thickness. Fig. 11 is a photograph of a substitute photograph of a film formation state in a concave portion by SEM (Electron Microscope). Fig. 12 is an enlarged photograph showing a specific portion in Fig. 11. As shown in Figs. 9 and 10, the "top" in Fig. 9 indicates the film thickness on the surface of the upper surface of the wafer W. The so-called bottom indicates the film thickness on the bottom surface in the concave portion 6. And side (

-24- 201114942 Top, side (middle) and side (bottom) are the film thicknesses of the upper, middle and lower sections of the side wall in the recess, respectively. As shown in FIG. 9, the conventional film formation method is to form 12.4 nm, 8.5 nm, 3.9 nm, 1.8 nm, and 0.8 nm in the order of the top, bottom, side (top), side (middle), and side (bottom). . In contrast, the method of the present invention forms 10.1 nm, 11.7 nm, 3.9 nm, 4.0 nm, and 3.7 nm ° in the above order, respectively, and thus the step coverage [(film thickness at each position/film thickness at the top) x 100] In the conventional film forming method, 6 8 · 7 %, 3 1.8 %, 14.4 %, 6.6% are formed in the order of bottom, side (top), side (middle), and side (bottom), respectively. . In contrast, the method of the present invention forms 1 16 · 1 %, 3 9 · 2 %, 3 9 · 6 %, and 3.6.9 %, respectively, in the above order. As a result, it was found that the step coverage of the bottom surface in the concave portion was 6 8.7% in the conventional film formation method, but the method of the present invention formed 1 1 6.1 %, which was greatly improved. Further, in the conventional film forming method, the side wall in the concave portion has a film thickness difference of 25.2 nm (=31.8-6.6) between the side (top) and the side (bottom), but in the method of the present invention, A film thickness difference of 2.3 nm (=39.2-36.9) is formed, and the film thickness can be uniformly formed not only in the sidewalls but also in the film thickness, and the film thickness can be sufficiently thickened as compared with the conventional film forming method. It can be seen that the step coverage can be improved. Further, in the above embodiment, Ar gas is used as the plasma gas, but it is not limited thereto. Other rare gases such as He or Ne may be used. Further, here, TiCl4 gas is used as a material gas, but it is not limited thereto, and -25-201114942 may also use TDMAT (Ti[N(CH3)2]4: tetramethylammonium titanium) gas or TDEAT (Ti) [N(C2H5)2]4: four times diethylammonium titanium) gas or the like. Further, the above embodiment is a case where a Ti film is formed by a plasma CVD method as an example of the formation of a Ti film. However, the present invention is not limited thereto, and the present invention can also be applied to the formation of a TiN film. In this case, when the Ti film is formed by the method of the present invention, the TiN film can be formed by additionally flowing a nitriding gas such as nitrogen (N 2 ) gas. Further, the nitriding gas is not limited to N2 gas, and NH3 gas, hydrazine (h2N-NH2) gas or methyl hydrazine (CH3-NH-NH2) gas may be used. In addition, although the semiconductor wafer is described as an example of the semiconductor wafer, the semiconductor wafer includes a germanium substrate or a compound semiconductor substrate such as GaAs, SiC, or GaN, and is not limited to the substrates. The invention is applicable to a glass substrate, a ceramic substrate, or the like used in a liquid crystal display device. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic block diagram showing an example of a plasma processing apparatus for carrying out the method of the present invention. Fig. 2 is a view showing an example of a state of the upper surface of the object to be processed when the film forming process is performed on the semiconductor wafer. Fig. 3 is a graph for explaining an optimum range of respective flow rates of a material gas and a reducing gas in the method of the present invention. Fig. 4 is a graph showing the relationship between the H2 flow rate and the film formation rate in the conventional film formation method in which the H2 flow rate is extremely large. Figure 5 is a graph showing the H2 flow rate and film formation rate when the cardiac flow rate is very small.

-26- S 201114942 is a chart. Fig. 6 is a chart in which a part of Fig. 5 is enlarged to be displayed. Fig. 7 is a graph showing the relationship between the flow rate of TiCl4 and the film formation rate when various flow rates are changed. Fig. 8 is a graph showing the relationship between the atomic ratio of chlorine to hydrogen (Cl/Η ratio) and the film formation rate when various helium flow rates are changed. FIG. 9 is a graph showing measurement 値 of the film thickness at each position in the concave portion. Fig. 1 is a view showing a measurement of the film thickness in the concave portion in a pattern. Fig. 11 is a photograph of a substitute photograph of a film formation state in a concave portion by SEM (electron microscopy). Fig. 12 is an enlarged photograph showing a specific portion in Fig. 11. Fig. 13 is a view showing a film forming method at the time of embedding a concave portion on the surface of a semiconductor wafer. [Main component symbol description] 2: Conductive layer 4: Insulation layer 6: Recessed portion 8: Ti film 10: TiN film 1 2: Barrier layer 2 〇: Plasma processing device 22: Processing container 28: Vacuum exhaust system -27- 201114942 3 2 : Vacuum pump 3 6 : Mounting table 3 8 : Heating means 40 : Shower head (gas introduction means) 56 : TiCl 4 gas source 58 : H 2 gas source 7 0 : Tube frequency power supply 74 : Plasma forming means 8 2 : Control Part 8 4 : Memory Media W: Semiconductor Wafer (Processed Body) -28-

Claims (1)

201114942 VII. Patent application scope: 1. A film forming method for accommodating a processed body having an insulating layer having a concave portion formed on a surface thereof in a vacuum-decomposable processing container, and supplying titanium to the processing container The method for forming a film containing titanium by reacting the gas with a reducing gas and a reducing gas by a plasma CVD method, wherein the reaction can be a reaction limit of the raw material gas The respective flow rates of the source gas and the reducing gas are set in a rapid reaction state. 2. The film forming method according to the first aspect of the invention, wherein the raw material gas is a chlorine-containing gas, and the reducing gas is a hydrogen-containing gas. 3. The film forming method according to the second aspect of the invention, wherein the C1/H ratio of the ratio of the number of chlorine atoms in the environment in the grain treatment to the atomic number of hydrogen in the environment can be formed in a range of 0.5 to 1.5. The respective flow rates of the source gas and the reducing gas are set. 4. The film forming method according to the second aspect of the invention, wherein the C1/H ratio of the ratio of the number of chlorine atoms in the environment in the processing container to the number of atoms of hydrogen can be in the range of 0.7 to 1.3. In this manner, the respective flow rates of the source gas and the reducing gas are set. The film forming method according to any one of the first to fourth aspects of the invention, wherein the nitriding gas is supplied into the processing container. [6] The film forming method of claim 5, wherein the nitrogenating gas is nitrogen. The film forming method according to any one of the first to sixth aspects of the invention, wherein the inner diameter or the width of the concave portion is 6 〇 nm or less. The method of forming a film according to any one of the preceding claims, wherein the material gas is TiC 14 gas and the reducing gas is H2 gas. A plasma processing apparatus which is a plasma processing apparatus for forming a titanium-containing film on a surface of a substrate having a recessed insulating layer, the method comprising: a processing container capable of vacuum evacuation; and a mounting table The method of placing the object to be processed in the processing container and having a function as a lower electrode; the heating means 'heating the object to be processed'; and the gas introducing means introducing a material gas into the processing container The gas is supplied as a function of the upper electrode: a gas supply means for supplying the various gases to the gas introduction means, and a plasma forming means for forming a plasma between the mounting table and the gas introduction means And a control unit that controls the film formation method as described in any one of claims 1 to 8. 1 0 · a kind of memory medium, which can be read in a computer program for controlling a plasma processing device, and when a plasma processing device is used to form a titanium-containing film on the surface of a processed object, the patent application scope is implemented. The film forming method according to any one of the first to eighth aspect, wherein the plasma processing apparatus includes: a processing container that can be evacuated by vacuum; and a mounting table that is placed in the processing container to form a surface There is a body to be treated having an insulating layer having a recessed portion, and a functional heating means as a lower electrode for heating the object to be processed; and a gas introducing means for introducing a material containing gas into the processing container. a gas supply means for supplying the various gases to the gas introduction means, and a plasma formation means for forming a plasma between the mounting table and the gas introduction means. And the control unit, which is the entire control device. £ -31 -