Method and apparatus for forming a metal silicide layer on a substrate

Abstract

A metal halide gas is supplied to the substrate with the exposed silicon layer to form a metal silicide layer. [Solution] The method includes the steps of heating the substrate with the exposed silicon layer to a temperature in the range of 490°C or higher and 600°C or lower, pre-supplying a source gas which is a metal halide gas containing a metal and a halogen that constitute the metal silicide, and alternately and repeatedly supplying the source gas and a reaction gas which reacts with the metal halide to obtain the metal to the substrate, thereby forming a layer of the metal on the surface of the silicon layer, and the metal silicide layer is formed by diffusing silicon from the silicon layer into the metal layer.

Description

[Technical Field]

[0001] The present disclosure relates to a method and apparatus for forming a metal silicide layer on a substrate. [Background technology]

[0002] In the manufacturing process of a semiconductor device, a process of forming various layers such as a metal layer and an insulating layer on a semiconductor wafer (hereinafter also referred to as a "wafer"), which is a substrate, is carried out. For example, Patent Document 1 discloses a process of forming a metal silicide, MoSi X The publication describes a method for selectively depositing materials. This method involves sequentially exposing a heated substrate to first and second doses of a MoF6 precursor and a Si2H6 precursor, followed by a third dose of a Si2H6 precursor. However, Patent Document 1 does not describe a method that takes into account the effects on other layers when a halogen-containing source gas is used as a metal silicide source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-522138 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for forming a metal silicide layer by supplying a metal halide gas to a substrate having an exposed silicon layer. [Means for solving the problem]

[0005] The present disclosure provides a method for forming a metal silicide layer on a substrate, comprising: heating the substrate with the exposed silicon layer to a temperature in the range of 490°C or more and 600°C or less; a step of preliminarily supplying a source gas, which is a metal halide gas containing a metal and a halogen that constitute the metal silicide, to the heated substrate; and alternately and repeatedly supplying the source gas and a reaction gas that reacts with the metal halide to obtain the metal to the substrate after the source gas has been preliminarily supplied, thereby forming a layer of the metal on the surface of the silicon layer, The metal silicide layer is formed by diffusing silicon from the silicon layer into the metal layer. Alternatively, the present disclosure provides a method for forming a metal silicide layer on a substrate, the method comprising: heating the substrate with the exposed silicon layer to a temperature in the range of 400°C or more and 510°C or less; a step of alternately supplying a source gas, which is a metal halide gas containing a metal and a halogen that constitute the metal silicide, and a reaction gas that reacts with the metal halide to obtain the metal, to the heated substrate, thereby forming a layer of the metal on the surface of the silicon layer; The metal silicide layer is formed by diffusing silicon from the silicon layer into the metal layer. [Effects of the Invention]

[0006] According to the present disclosure, a metal silicide layer can be formed by supplying a metal halide gas to a substrate with an exposed silicon layer. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a vertical cross-sectional side view showing an example of the configuration of a processing apparatus that forms a molybdenum silicide layer; [Figure 2] FIG. 2 is a schematic diagram showing the formation of a molybdenum layer before it becomes a molybdenum silicide layer. [Figure 3] FIG. 2 is a reaction model diagram showing the state of a wafer surface in forming a molybdenum layer. [Figure 4] 1 is a graph showing the relationship between the supply time of MoCl5 and the amount of Mo removed. [Figure 5]4 is a time chart showing a supply sequence of various gases for forming a molybdenum layer according to the first embodiment. [Figure 6] FIG. 2 is a reaction model diagram showing the state of the wafer surface according to the first embodiment. [Figure 7] 6 is a time chart showing a supply sequence of various gases for forming a molybdenum layer according to the second embodiment. [Figure 8] FIG. 10 is a reaction model diagram showing the state of a wafer surface according to the second embodiment. [Figure 9] 1 is an electron microscope photograph of a molybdenum layer formed at a wafer heating temperature of 550° C. [Figure 10] 1 is an electron microscope photograph of a molybdenum layer formed at a wafer heating temperature of 450° C. [Figure 11] 1 shows the results of XRD analysis of the molybdenum silicide layer obtained in each experiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] <Processing equipment> The present disclosure relates to a technique for forming a metal silicide layer by using a metal halide gas to form a metal layer on a silicon layer 51 exposed on a wafer W, and then diffusing silicon toward the metal layer. Hereinafter, an example will be described in which a molybdenum (Mo) layer is formed as a metal layer using molybdenum pentachloride (MoCl5) gas, which is a source gas containing a metal halide, and hydrogen (H2) gas, which is a reactive gas that reacts with MoCl5 to obtain Mo.

[0009] FIG. 1 is a longitudinal side view of a processing apparatus 1 according to this embodiment. This processing apparatus 1 is configured to form a Mo layer 6 by thermal atomic layer deposition (ALD), which alternately supplies MoCl5 gas and H2 gas to the surface of a heated wafer W. Compared to using plasma or other methods for activating source gases and reactive gases, thermal ALD has less anisotropy in the direction of movement of activated species, allowing them to move freely in both horizontal and vertical directions. This makes it less subject to structural constraints on the semiconductor device, and allows the Mo layer 6 to be formed even on semiconductor devices with complex structures or recesses with high aspect ratios.

[0010] The processing apparatus 1 includes a substantially cylindrical processing vessel 10 made of a metal that is corrosion-resistant to chlorine. A cylindrical exhaust chamber 11, for example, that protrudes downward is formed in the center of the bottom of the processing vessel 10, and an exhaust path 12 is connected to the side of the exhaust chamber 11. An exhaust unit 13 including a pressure adjustment valve, for example, a butterfly valve, is connected to the exhaust path 12, and the processing vessel 10 can be evacuated to a predetermined vacuum pressure.

[0011] A loading / unloading port 14 is formed on the side of the processing vessel 10 for loading / unloading the wafer W between the processing vessel 10 and a vacuum transfer chamber (not shown), and the loading / unloading port 14 is configured to be freely opened and closed by a gate valve 15. Furthermore, a heater 16 for adjusting the temperature inside the processing vessel 10 is embedded in the wall portion constituting the processing vessel 10.

[0012] A mounting table 2 for holding a wafer W in a substantially horizontal position is provided within the processing vessel 10. The mounting table 2 is supported by a support portion 21 extending from the bottom of the exhaust chamber 11. A heater 20, which is a heating portion, is embedded in the mounting table 2, and the wafer W can be heated to a set temperature. The mounting table 2 is provided with lift pins (not shown) for holding and elevating the wafer W. The wafer W can be transferred between the mounting table 2 and an external transfer mechanism (not shown) by raising and lowering the lift pins.

[0013] A flat, disk-shaped showerhead 3 is attached to the ceiling surface of the processing vessel 10 to supply processing gas toward the wafer W. A diffusion chamber 31 for diffusing the gas is formed inside the showerhead 3, and a number of discharge holes 32 for discharging the gas toward the wafer W are provided in a distributed manner on the bottom surface of the showerhead 3. Furthermore, a heater 36 is embedded in the upper surface of the showerhead 3, for example.

[0014] The downstream end of a gas supply path 40 is connected to the diffusion chamber 31 of the showerhead 3. On the upstream side of this gas supply path 40, supply paths 41 and 42 for MoCl gas as a source gas and H gas as a reactive gas, and a supply path 43 for nitrogen (N) gas as a purge gas join together.

[0015] A MoCl5 gas supply source 410 is connected to the upstream end of a MoCl5 gas supply flow path 41, and a flow rate adjuster M41 and a valve V41 are disposed therein, in order from upstream to downstream. The MoCl5 gas supply source 410 includes a source container containing solid MoCl5. The MoCl5 gas is heated and sublimated in the source container, and is picked up by a carrier gas, such as N2 gas. A mixed gas of MoCl5 and N2 is then sent to the supply flow path 41 as a source gas. An H2 gas supply source 420 is connected to the upstream end of an H2 gas supply flow path 42, and a flow rate adjuster M42 and a valve V42 are disposed therein, in order from upstream to downstream. An N2 gas supply source 430 is connected to the upstream end of an N2 gas supply flow path 43, and a flow rate adjuster M43 and a valve V43 are disposed therein, in order from upstream to downstream.

[0016] In this example, the raw material gas supply unit is composed of a MoCl5 gas supply source 410, a MoCl5 gas supply flow path 41, and a gas supply path 40. The reactive gas supply unit is composed of an H2 gas supply source 420, a H2 gas supply flow path 42, and the gas supply path 40.

[0017] As shown in FIG. 1, the processing apparatus 1 having the above-described configuration includes a control unit 100. The control unit 100 is configured by a computer including a storage unit that stores a program, a memory, and a CPU. The program is composed of instructions (steps) to execute the process of forming the Mo layer 6 by outputting a control signal from the control unit 100 to each part of the processing apparatus 1 and performing control related to the supply and cutoff of each gas and the heating of the wafer W. The program is stored in a storage unit of a computer, such as a flexible disk, a compact disk, a hard disk, an MO (magneto-optical disk), a nonvolatile memory, etc., and is read from this storage unit and installed in the control unit 100.

[0018] <Problems in Forming the Mo Layer 6> The problems in forming the Mo layer by the thermal ALD method using the processing apparatus 1 described above will be described. FIG. 2 schematically shows the structure of a region near the surface of the wafer W on which the Mo layer is formed using the processing apparatus 1. The surface of the wafer W is covered with a silicon oxide layer (SiO layer 52) which is an insulating layer, and a recess 50 is formed in the SiO layer 52. At the lower end of the recess 50, a silicon layer 51 which is an upper surface side region of the silicon substrate forming the main body of the wafer W is exposed.

[0019] For the wafer W having the above-described structure, the processing apparatus 1 forms the Mo layer 6 on the surface of the silicon layer 51 exposed in the recess 50. Here, the inventors understand that in the case of thermal ALD using MoCl5 gas and H2 gas, it is possible to form the Mo layer 6 under the condition that the wafer W is heated to a temperature within a range of, for example, 400 ° C to 600 ° C. On the other hand, it has been found that different problems occur in forming the Mo layer 6 depending on the heating temperature range of the wafer W.

[0020] First, the problems in forming the Mo layer 6 under the condition that the wafer W is heated to a relatively high temperature of, for example, 490 ° C or higher, particularly 550 ° C or higher, while referring to the reaction model shown in FIG. 3 will be described. When MoCl5 gas is supplied to the silicon layer 51 exposed on the surface of the wafer W, as shown in FIG. 3(a), MoCl x71 is bonded to Si. Then, when H2 gas is supplied, MoCl x 71 reacts with H2 to form SiCl4 72 and HCl 73, while MoCl x The Mo atoms that constituted 71 remain on the silicon layer 51 (FIG. 3(b)).

[0021] These reactions can be expressed as an overall reaction formula, as shown in formula (1) below (formula (1) shows the stoichiometric ratio when, for example, X=5). 2MoCl x (g) + 6Si + H2(g) →2MoSi2+2SiCl4(g)+2HCl(g) …(1) According to the formula (1), as the deposition of Mo on the silicon layer 51 progresses, etching progresses in which Si constituting the silicon layer 51 turns into gas and is released (FIG. 3(c)). As a result, the surface of the silicon layer 51 below the Mo layer 6 shown in FIG. 2 becomes rough, which may increase the contact resistance between the silicon layer 51 and the molybdenum silicide (MoSi) layer formed from the Mo layer 6.

[0022] Therefore, a method of forming the Mo layer 6 by a reaction mechanism different from that of formula (1) by limiting the heating temperature of the wafer W to, for example, 510°C or less, particularly 500°C or less (details will be explained later in FIG. 8). However, as shown in FIG. 4, it was found that MoCl5, which is the raw material of the Mo layer 6, also acts as an etching gas for Mo.

[0023] The horizontal axis of Figure 4 represents the supply time (seconds) of MoCl5 gas to the Mo substrate, and the vertical axis represents the amount of Mo substrate removal (nm). Figure 4 shows that the longer the MoCl5 gas supply time, the greater the amount of Mo removal. It was also found that the lower the heating temperature of the Mo substrate, the greater the rate of increase in the amount of removal. Therefore, even if MoCl5 gas is used as the source gas, the formed Mo may be etched, making it difficult to efficiently form the Mo layer 6. In consideration of the problems described with reference to FIGS. 3 and 4, in each of the embodiments described below, the process for forming the Mo layer 6 is varied depending on the heating temperature of the wafer W.

[0024] First Embodiment The first embodiment is applied when the wafer W is heated to a temperature in the range of 490°C or higher and 600°C or lower. In the first embodiment, a pre-supply of a highly concentrated source gas is performed on the wafer W before the formation of the Mo layer 6 by thermal ALD. FIG. 5 is a time chart showing an example of the supply sequence of various gases (source gas: MoCl5 gas, reactive gas: H2 gas, purge gas: N2) involved in the process of forming the Mo layer 6 performed using the processing apparatus 1 described above. This time chart schematically shows the timing of supplying and shutting off various gases to the processing chamber 10.

[0025] In the time chart of Figure 5, T 01 ~T 02 During this period, a preliminary supply of MoCl5 gas is performed. The supply time of MoCl5 gas in the preliminary supply is longer than the supply time of MoCl5 gas in each cycle during thermal ALD in which MoCl5 gas and H2 gas are alternately supplied (the period from time t1 to t2 in FIG. 5). The supply time of MoCl5 gas in the preliminary supply is, for example, 30 seconds within a range of 5 seconds to 90 seconds. On the other hand, the supply time of MoCl5 gas in each cycle during thermal ALD is, for example, 0.5 seconds within a range of 0.1 seconds to 1 second.

[0026] During the preliminary supply, the pressure in the processing vessel 10 is increased by the pressure adjustment valve of the exhaust unit 13 compared to when thermal ALD is performed, thereby supplying a high-concentration MoCl gas to the wafer W. The pressure in the processing vessel 10 (processing atmosphere for the wafer W) during the preliminary supply is, for example, 5.33 kPa (40 Torr) within a range of 1.33 kPa to 5.33 kPa (10 Torr to 40 Torr). Meanwhile, the pressure in the processing vessel 10 during the period when thermal ALD is being performed is, for example, 200 Pa (1.5 Torr) within a range of 133.3 Pa to 266.6 Pa (1.0 Torr to 2.0 Torr).

[0027] The control of supply and cutoff of each gas is controlled by the control unit 100, and the supply of various gases is executed based on the time chart shown in Fig. 5. That is, the control unit 100 controls the opening and closing of valves V41, V42, and V43, executes the supply and cutoff of each gas, and sets the flow rates of each flow rate adjustment unit M41, M42, and M43.

[0028] The process for forming the Mo layer 6 will be described with reference to the time chart of FIG. 5 and the reaction model of FIG. In the processing apparatus 1, first, gate valve 15 is opened, and a transfer mechanism installed in a vacuum transfer chamber (not shown) loads the wafer W into processing chamber 10 through load / unload port 14. The loaded wafer W is transferred from the transfer mechanism to mounting table 2 via lift pins (not shown) and placed on the upper surface of mounting table 2. Next, the transfer mechanism is retracted from processing chamber 10, and gate valve 15 is closed. Then, exhaust unit 13 evacuates processing chamber 10, and the pressure inside processing chamber 10 is adjusted to the pressure during preliminary supply of MoCl gas. Next, heater 20 heats wafer W to 550°C, which is within a range of 490°C to 600°C (wafer W heating step).

[0029] After that, at time T 01 At this time, preliminary supply of MoCl5 gas is started. 02 MoCl5 gas is preliminarily supplied for a preset time (for example, 30 seconds) until the temperature reaches the predetermined value (MoCl5 gas preliminarily supplying step). As shown in Fig. 6(a), the MoCl gas supply during the preliminary supply period x The bonding of 71 to Si is similar to the supply of MoCl5 gas during thermal ALD described with reference to FIG. 3(a).

[0030] During the preliminary supply period, the reaction of the following formula (2) progresses on the surface of the wafer W due to a thermal reaction, and Mo can be precipitated on the surface of the silicon layer 51 (FIG. 6(b)). MoCl x +Si→SiCl4(g)+Mo …(2) On the other hand, as explained with reference to FIG. 4, MoCl5 gas has the effect of etching Mo, and the following reaction (3) simultaneously proceeds. XMoCl x (g)+Mo →XMoCl x―1 (g)+MoCl x (g) + Cl2…(3)

[0031] However, as explained in FIG. 4, the etching action of MoCl5 gas on Mo can be suppressed to a small extent by increasing the heating temperature of the wafer W and increasing the supply time of MoCl5 gas. Therefore, in the range of 490°C or higher and 600°C or lower, it has been found that Mo precipitation can be dominant in terms of the balance between Mo precipitation by reaction (2) and Mo etching by reaction (3). As a result, it is possible to cover the surface of the silicon layer 51 with Mo, as shown in FIG. 6(c).

[0032] 3(c) and equation (1), even if H2 gas is supplied, etching of Si does not progress easily when the surface of the silicon layer 51 is covered with Mo. Therefore, by preliminarily supplying MoCl5 gas to cover the surface of the silicon layer 51 with Mo, and then performing thermal ALD using MoCl5 gas and H2 gas, a Mo layer 6 with sufficient thickness can be formed (step of forming a Mo layer 6 on the surface of the silicon layer 51).

[0033] Therefore, after the preliminary supply is performed for the aforementioned 30 seconds, the supply of MoCl5 gas is stopped, and T 03 ~T 04 During this period, N2 gas is supplied to purge the inside of the processing vessel 10. At this time, the pressure inside the processing vessel 10 is adjusted to the pressure during thermal ALD.

[0034] 5, one cycle is "supply of MoCl5 gas from t1 to t2 → supply (purge) of N2 gas from t3 to t4 → supply of H2 gas from t5 to t6 → supply (purge) of N2 gas from t7 to t8," and this cycle is repeated, for example, several tens to several hundred cycles, to form a Mo layer 6 of a desired thickness. The supply period of H2 gas (period from t5 to t6) can be, for example, about 10 times the supply period of MoCl5 gas (period from t1 to t2).

[0035] When the Mo layer 6 is formed by the thermal ALD method, silicon diffuses from the silicon layer 51 into the Mo layer 6, forming a molybdenum silicide layer. Here, MoSi crystal structures include hexagonal (h-MOSi2, resistivity: 409 μΩ-cm) and tetragonal (t-MOSi2, resistivity: 60 μΩ-cm). As shown in the experimental results described below, it has been found that when MoCl5 gas is pre-supplied and the heating temperature of the wafer W is adjusted to a range of 490°C or higher and 600°C or lower, it is possible to form a Mo layer 6 containing tetragonal crystals with low resistivity.

[0036] After the preset number of cycles have been performed, the heating of the wafer W is stopped. After purging the processing vessel 10, the evacuation is stopped, and the gate valve 15 is opened to allow an external transfer mechanism to enter. The wafer W is then unloaded in the reverse order of the loading procedure.

[0037] According to the processing apparatus 1 of the first embodiment described above, MoCl5 gas can be supplied to the wafer W with the exposed silicon layer 51 to form the Mo layer 6. In particular, by pre-supplying MoCl5 gas, the surface of the silicon layer 51 can be covered with Mo. After the surface of the silicon layer 51 is covered with Mo, etching of Si based on formula (1) is less likely to proceed, and therefore the Mo layer 6 can be formed while suppressing roughness of the surface of the silicon layer 51.

[0038] <Second embodiment> The first embodiment is applied when the wafer W is heated to a temperature in the range of 400°C to 510°C. As described with reference to FIG. 4, the effect of MoCl5 gas on etching Mo tends to increase with the decrease in the heating temperature of the wafer W, as the amount of Mo removed increases with the increase in the supply time of MoCl5 gas. Therefore, in the range of 400°C to 510°C, it is difficult to precipitate Mo or it takes a long time to cover the surface of the silicon layer 51, considering the balance between the Mo precipitation due to the reaction of formula (2) and the Mo etching due to the reaction of formula (3). Therefore, it may be difficult to adopt the method of covering the surface of the silicon layer 51 with Mo by pre-supplying MoCl5 gas before performing thermal ALD, as in the first embodiment described with reference to FIG. 6(c).

[0039] On the other hand, the deposition of Mo and the etching of Si based on formula (1) described with reference to Figures 3(a) to (c) proceed more easily as the heating temperature of the wafer W increases. For example, when the wafer W is heated to a relatively high temperature, such as 490°C or higher, particularly 550°C or higher, the growth rate of the Mo layer 6 can be increased, but the roughness of the silicon layer 51 also increases. In contrast, when the wafer W is heated to a relatively low temperature, such as 510°C or lower, particularly 450°C or lower, the growth rate of the Mo layer 6 is slow, but the degree of roughness of the silicon layer 51 can also be kept low. Note that in the above description, the overlapping range of 490°C or higher and 510°C or lower is a temperature range in which the growth rate of the Mo layer 6 and the roughness of the silicon layer 51 are moderate. This is a heating temperature range in which either method can be adopted depending on the allowable degree of roughness of the silicon layer 51 and the growth rate required for the Mo layer 6.

[0040] Therefore, for example, if the thickness of the Mo layer 6 to be formed is within a range of 0.5 nm to 10 nm, the heating temperature of the wafer W is limited to 400° C. to 510° C. As a result, the Mo layer 6 can be formed while suppressing roughness of the surface of the silicon layer 51, without pre-supplying MoCl gas.

[0041] 7 is a time chart showing an example of a supply sequence of various gases according to the second embodiment. 01 ~T 02 Preparatory supply of MoCl5 gas for period T 03 ~T 04 Except for the fact that purging by supplying N2 gas in step 1 is omitted, thermal ALD is performed in the same manner as in the example described with reference to Fig. 5. The operation of the processing apparatus 1 is also the same as in the first embodiment except for the above-mentioned differences, and therefore a repeated description will be omitted.

[0042] As a result, similar to the reaction model described using FIGS. 3(a) and 3(b), even when etching of the silicon layer 51 based on formula (1) progresses, the degree of etching can be kept small, and molybdenum for forming the Mo layer 6 can be precipitated on the surface of the silicon layer 51 (FIG. 8).

[0043] In the first and second embodiments described above, the Mo layer 6 is formed using MoCl gas as the source gas and H gas as the reactive gas, but the metal for forming the metal silicide is not limited to this example. For example, a metal halide gas such as TiCl, WCl, or WCl may be used and reacted with H gas as the reactive gas to form a metal layer such as a Ti layer or a W layer.

[0044] Furthermore, the method for forming a metal layer such as the Mo layer 6 is not limited to thermal ALD, which alternately supplies a source gas and a reactive gas. For example, the source gas and the reactive gas may be simultaneously supplied to the heated wafer W, or a mixed gas of the source gas and the reactive gas may be supplied to deposit Mo, a reaction product, on the wafer W. In this case, too, when the heating temperature of the wafer W is in the range of 490°C or higher and 600°C or lower, a pre-supply is performed in which only the source gas is supplied. On the other hand, when the heating temperature of the wafer W is in the range of 400°C or higher and 510°C or lower, formation of the Mo layer 6 is started without pre-supply.

[0045] Furthermore, the configuration of the apparatus for forming the Mo layer 6 is not limited to the example shown in Fig. 1. For example, a batch-type film formation apparatus that simultaneously forms films on a plurality of wafers W may be used. In this case, as described with reference to Figs. 5 and 7, by varying the process for forming the Mo layer 6 depending on the heating temperature of the wafers W, the Mo layer 6 can be formed while suppressing roughness of the surface of the silicon layer 51.

[0046] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Example]

[0047] (experiment) Using the processing apparatus 1, a Mo layer 6 was formed on the surface of a silicon wafer W by a thermal ALD method, and the heating temperature of the wafer W and the influence of whether or not a preliminary supply was performed were confirmed. A. Experimental Conditions (Example 1-1) The heater 20 of the mounting table 2 was set to a temperature of 450°C. The supply times of MoCl5 gas, N2 gas, H2 gas, and N2 gas were set to 0.1 seconds, 0.3 seconds, 3.0 seconds, and 0.4 seconds, respectively. Thermal ALD was performed by performing 265 cycles of these gas supplies as one cycle. The mass flow rate of MoCl5 contained in the source gas was 300 mg / min, and the supply flow rate of H2 gas was 10 L / min (based on 0°C and 1 atmosphere). The pressure in the processing chamber 10 was set to a high pressure of 5.33 kPa (40 Torr) (stress test). No preliminary supply of MoCl5 gas was performed. Example 1-2 The Mo layer 6 was formed under the same conditions as in Example 1-1, except that the set temperature of the heater 20 was set to 500°C. (Comparative Example 1-3) The Mo layer 6 was formed under the same conditions as in Example 1-1, except that the set temperature of the heater 20 was set to 550°C. (Reference Example 2-1) A Mo layer 6 was formed under the same conditions as in Example 1-1, except that a preliminary supply of MoCl gas was performed for 60 seconds before performing thermal ALD. The pressure in the processing vessel 10 and the supply flow rate of MoCl gas during the preliminary supply period were the same as those during thermal ALD. Example 2-2 The Mo layer 6 was formed under the same conditions as in Reference Example 2-1, except that the set temperature of the heater 20 was set to 500°C. Example 2-3 The Mo layer 6 was formed under the same conditions as in Reference Example 2-1, except that the set temperature of the heater 20 was set to 550°C.

[0048] B. Experimental Results 9(a) and 9(b) show magnified TEM (Transmission Electron Microscopy) micrographs of Comparative Example 1-3 and Example 2-3, in which the wafer W was heated to a temperature of 550°C. In Comparative Example 1-3, in which MoCl5 gas was not pre-supplied, the average thickness of the Mo layer 6 was 50 nm (FIG. 9(a)). It can also be seen that the surface of the silicon layer 51 below the Mo layer 6 was significantly roughened. On the other hand, in Example 2-3, in which MoCl5 gas was pre-supplied, the average thickness of the Mo layer 6 was 150 nm (FIG. 9(b)). No significant roughness was observed on the surface of the silicon layer 51 below the Mo layer 6.

[0049] Next, TEM magnified micrographs of Example 1-1 and Reference Example 2-1, in which the wafer W was heated to a temperature of 450°C, are shown in Figures 10(a) and 10(b), respectively. In Example 1-1, in which MoCl5 gas was not pre-supplied, the average thickness of the Mo layer 6 was 40 nm (Figure 9(a)). Furthermore, the surface of the silicon layer 51 below the Mo layer 6 did not exhibit significant roughness, as in Comparative Example 1-3. On the other hand, in Reference Example 2-1, in which MoCl5 gas was pre-supplied, the average thickness of the Mo layer 6 was 38 nm, and the growth rate of the Mo layer 6 was slower than in Example 2-3 (Figure 10(b)). This is thought to be due to the fact that Mo deposited by the pre-supply of MoCl5 gas was removed by etching despite the pre-supply of MoCl5 gas, and the low heating temperature of the wafer W resulted in a slow growth rate of the Mo layer 6. Furthermore, significant roughness was not observed on the surface of the silicon layer 51 below the Mo layer 6.

[0050] 11 shows the results of XRD (X-ray Diffraction) analysis of the Mo layers 6 formed in each of the examples, comparative examples, and reference examples after leaving them for approximately 72 hours. All experimental results confirmed the formation of molybdenum silicide (MoSi2). Furthermore, in Examples 1-1 and 1-2 and Comparative Example 1-3, in which MoCl5 gas was not pre-supplied, the MoSi2 formed was a hexagonal crystal (h-MOSi2) with high resistivity, and tetragonal crystal (t-MOSi2) with low resistivity was hardly observed, regardless of the heating temperature of the wafer W.

[0051] In contrast, in Reference Example 2-1 and Examples 2-2 and 2-3, in which MoCl gas was preliminarily supplied, as the heating temperature of the wafer W increased, a peak in the diffraction angle (2θ: approximately 23°) was confirmed, indicating the inclusion of t-MOSi2 with low resistivity. [Explanation of symbols]

[0052] W wafer 1 Processing equipment 100 control section 20 Heater 410 MoCl5 gas source 420 H2 gas supply source

Claims

1. 1. A method for forming a metal silicide layer on a substrate, comprising: heating the substrate with the exposed silicon layer to a temperature in the range of 490°C or more and 600°C or less; a step of preliminarily supplying a source gas, which is a metal halide gas containing a metal and a halogen that constitute the metal silicide, to the heated substrate; and alternately and repeatedly supplying the source gas and a reaction gas that reacts with the metal halide to obtain the metal to the substrate after the source gas has been preliminarily supplied, thereby forming a layer of the metal on the surface of the silicon layer, The method wherein the metal silicide layer is formed by diffusing silicon from the silicon layer into the metal layer.

2. 2. The method according to claim 1, wherein the supply time of the source gas in the preliminary supply is longer than the supply time of the source gas in each supply when the source gas and the reaction gas are alternately supplied.

3. 3. The method according to claim 2, wherein the supply time of the source gas in the preliminary supply is in the range of 5 seconds to 90 seconds.

4. 2. The method according to claim 1, wherein the pressure of the atmosphere in which the substrate is placed during the preliminary supply is higher than the pressure of the atmosphere in which the substrate is placed during the alternate supply of the source gas and the reaction gas.

5. The method of claim 4 , wherein the pressure of the processing atmosphere for the substrate in the preliminary supply is in the range of 1.33 kPa or more and 5.33 kPa or less.

6. 1. A method for forming a metal silicide layer on a substrate, comprising: heating the substrate with the exposed silicon layer to a temperature in the range of 400°C or more and 510°C or less; a step of alternately supplying a source gas, which is a metal halide gas containing a metal and a halogen that constitute the metal silicide, and a reaction gas that reacts with the metal halide to obtain the metal, to the heated substrate, thereby forming a layer of the metal on the surface of the silicon layer; The method wherein the metal silicide layer is formed by diffusing silicon from the silicon layer into the metal layer.

7. 7. The method according to claim 2, wherein the supply time of the source gas each time when the source gas and the reaction gas are alternately supplied is within a range of 0.1 second to 1 second.

8. 7. The method according to claim 4, wherein the pressure of the processing atmosphere for the substrate when the source gas and the reaction gas are alternately supplied is in the range of 133.3 Pa or more and 266.6 Pa or less.

9. 10. The method of claim 1 or 6, wherein the metal is molybdenum and the metal silicide is molybdenum silicide.

10. 10. The method of claim 9, wherein the molybdenum silicide comprises a tetragonal crystal.

11. 10. The method of claim 9, wherein the source gas is molybdenum pentachloride gas and the reactant gas is hydrogen gas.

12. 1. An apparatus for forming a metal silicide layer on a substrate, comprising: a processing vessel including a mounting table on which the substrate with the exposed silicon layer is placed; a heating unit that heats the substrate placed on the mounting table; a source gas supply unit for supplying a source gas, which is a metal halide gas containing a metal and a halogen that constitute the metal silicide, to the processing vessel; a reaction gas supply unit for supplying a reaction gas to the processing vessel so as to react with the metal halide to obtain the metal; a control unit, the control unit is configured to output a control signal for executing the steps of: heating the substrate to a temperature in a range of 490° C. or more and 600° C. or less; pre-supplying the source gas to the heated substrate; and alternately and repeatedly supplying the source gas and the reaction gas to the substrate after the source gas has been pre-supplied, thereby forming the metal layer on a surface of the silicon layer; The device wherein the metal silicide layer is formed by diffusing silicon from the silicon layer into the metal layer.

13. 1. An apparatus for forming a metal silicide layer on a substrate, comprising: a processing vessel including a mounting table on which the substrate with the exposed silicon layer is placed; a heating unit that heats the substrate placed on the mounting table; a source gas supply unit for supplying a source gas, which is a metal halide gas containing a metal and a halogen that constitute the metal silicide, to the processing vessel; a reaction gas supply unit for supplying a reaction gas to the processing vessel so as to react with the metal halide to obtain the metal; a control unit, the control unit is configured to output a control signal for executing a step of heating the substrate to a temperature in a range of 400° C. or more and 510° C. or less, and a step of alternately and repeatedly supplying the source gas and the reaction gas to the heated substrate to form the metal layer on the surface of the silicon layer; The device wherein the metal silicide layer is formed by diffusing silicon from the silicon layer into the metal layer.

14. 14. The device of claim 12 or 13, wherein the metal is molybdenum and the metal silicide is molybdenum silicide.

15. 15. The apparatus of claim 14, wherein the source gas is molybdenum pentachloride gas and the reactant gas is hydrogen gas.

Images