Film deposition method and film deposition apparatus

Abstract

To provide a technique capable of suppressing an increase in resistivity of a metal film when a film containing silicon atoms and nitrogen atoms is formed on the metal film.SOLUTION: A film deposition method according to one aspect of the present disclosure is a deposition method in which a film containing silicon atoms and nitrogen atoms is formed on a surface of a substrate, the substrate having the surface with a metal film. The film deposition method includes the steps of: forming a seed layer containing silicon atoms and nitrogen atoms on the surface by supplying a first silicon-containing gas and a first nitriding gas to the substrate in a state where the substrate is maintained at a first temperature; and forming a bulk layer containing silicon atoms and nitrogen atoms on the seed layer by supplying a second silicon-containing gas and a second nitriding gas to the substrate in a state where the substrate is maintained at a second temperature greater than the first temperature.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a film forming method and a film forming apparatus. [Background technology]

[0002] A method for forming a silicon oxide film on a tungsten film by atomic layer deposition (ALD) using a silicon-containing gas and oxygen active species is known (see, for example, Patent Document 1). In Patent Document 1, a first silicon oxide film is formed by low-temperature film formation at 25 to 350°C, and then a second silicon oxide film is formed by medium- to high-temperature film formation at 500 to 750°C, thereby suppressing oxidation of the tungsten film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-29582 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique capable of suppressing an increase in resistivity of a metal film when a film containing silicon atoms and nitrogen atoms is formed on the metal film. [Means for solving the problem]

[0005] A film formation method according to one embodiment of the present disclosure is a film formation method for forming a film containing silicon atoms and nitrogen atoms on a surface of a substrate having a metal film on the surface, the method comprising the steps of: supplying a first silicon-containing gas and a first nitriding gas to the substrate while maintaining the substrate at a first temperature, to form a seed layer containing silicon atoms and nitrogen atoms on the surface; and supplying a second silicon-containing gas and a second nitriding gas to the substrate while maintaining the substrate at a second temperature higher than the first temperature, to form a bulk layer containing silicon atoms and nitrogen atoms on the seed layer. Effect of the Invention

[0006] According to the present disclosure, when a film containing silicon atoms and nitrogen atoms is formed on a metal film, an increase in resistivity of the metal film can be suppressed. [Brief description of the drawings]

[0007] [Figure 1] 2 is a flowchart illustrating a film forming method according to an embodiment. [Diagram 2] 1A to 1C are cross-sectional views illustrating a film forming method according to an embodiment. [Diagram 3] 1 is a vertical cross-sectional view showing a film forming apparatus according to an embodiment. [Figure 4] 1 is a horizontal cross-sectional view showing a film forming apparatus according to an embodiment. [Diagram 5] FIG. 13 is a graph showing the relationship between the substrate temperature and the sheet resistance of a Ru film. [Figure 6] FIG. 13 is a diagram showing the relationship between the thickness of a seed layer and the wiring resistance of a Ru film. [Figure 7] FIG. 13 is a diagram showing the relationship between the deposition method of the bulk layer and the sheet resistance of a Ru film. [Figure 8] FIG. 1 is a diagram showing an interface state between a Ru film and a SiN film. [Figure 9] FIG. 1 is a diagram showing an interface state between a Ru film and a SiN film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In all of the accompanying drawings, the same or corresponding members or parts are designated by the same or corresponding reference numerals, and duplicated descriptions will be omitted.

[0009] [Film formation method] A film forming method according to an embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a flowchart showing the film forming method according to the embodiment. Fig. 2 is a cross-sectional view showing the film forming method according to the embodiment. In the embodiment, a case will be described in which a silicon nitride (SiN) film, which is an example of a film containing silicon (Si) atoms and nitrogen (N) atoms, is formed on a ruthenium (Ru) film, which is an example of a metal film.

[0010] In step S1, as shown in FIG. 2(a), a substrate 100 is prepared. The substrate 100 has an insulating film 101, a barrier metal film 102, and a Ru film 103. The insulating film 101 is, for example, a thermal oxide film. The barrier metal film 102 is provided on the insulating film 101. The barrier metal film 102 is, for example, a titanium nitride (TiN) film. The Ru film 103 is provided on the barrier metal film 102. The Ru film 103 is formed by, for example, a physical vapor deposition (PVD) method. The Ru film 103 may be heat-treated, for example, in a reduced pressure atmosphere or an inert gas atmosphere maintained at 600° C. or more and 700° C. or less. In this case, the crystal grain size of the Ru film 103 can be increased to reduce the resistivity.

[0011] Step S2 is performed after step S1. In step S2, the temperature of the substrate 100 is adjusted to a first temperature. For example, the substrate 100 is accommodated in a processing vessel, and the processing vessel is heated by a heater so that the temperature of the substrate 100 becomes the first temperature. The first temperature is, for example, 550° C. or lower. In this case, even if the Ru film 103 is exposed to a high temperature in step S3, the resistivity of the Ru film 103 is unlikely to increase.

[0012] Step S3 is performed after step S2. In step S3, while the temperature of the substrate 100 is maintained at a first temperature, as shown in FIG. 2(b), a seed layer 104 is formed on the Ru film 103. The seed layer 104 is, for example, a SiN seed layer. The seed layer 104 can be formed by, for example, a thermal ALD method in which a first silicon-containing gas is alternately supplied to the substrate 100 and a first nitriding gas is alternately supplied to the substrate 100. In this case, the seed layer 104 is easily formed conformally along the surface of the Ru film 103. The first silicon-containing gas is, for example, hexachlorodisilane (HCD) gas. The first nitriding gas is, for example, ammonia (NH3) gas. The thickness of the seed layer 104 is, for example, thinner than the thickness of the bulk layer 105. The thickness of the seed layer 104 is, for example, 0.6 nm or more. In this case, even if the Ru film 103 is exposed to a high temperature in step S3, the resistivity of the Ru film 103 is unlikely to increase.

[0013] Step S4 is performed after step S3. In step S4, the temperature of the substrate 100 is changed from the first temperature to the second temperature. The second temperature is higher than the first temperature. The second temperature is, for example, 600° C. or higher. In this case, it is easy to form a high-quality bulk layer 105 in step S5.

[0014] Step S5 is performed after step S4. In step S5, while the temperature of the substrate 100 is maintained at the second temperature, as shown in FIG. 2(c), a bulk layer 105 is formed on the seed layer 104. The bulk layer 105 can be formed by, for example, a plasma ALD method in which the supply of a second silicon-containing gas to the substrate 100 and the exposure of the substrate 100 to plasma generated from the second nitriding gas are alternately repeated. In this case, a high-quality bulk layer 105 can be formed conformally along the surface of the seed layer 104. The second silicon-containing gas is, for example, a gas different from the first silicon-containing gas. The second silicon-containing gas is, for example, dichlorosilane (DCS) gas. The second nitriding gas is, for example, the same gas as the first nitriding gas. The second nitriding gas is, for example, ammonia gas.

[0015] By performing the above steps S1 to S5, the SiN film 106 in which the seed layer 104 and the bulk layer 105 are laminated on the Ru film 103 can be formed.

[0016] Incidentally, when the SiN film 106 is formed on the Ru film 103 at high temperature, silicon (Si) atoms contained in the SiN film 106 diffuse into the Ru film 103, forming a ruthenium silicide (RuSi) layer in the Ru film 103. When the RuSi layer is formed in the Ru film 103, the resistance of the Ru film 103 increases.

[0017] In the film forming method according to the embodiment, the seed layer 104 is formed on the Ru film 103 at a low temperature (first temperature), and then the bulk layer 105 is formed at a high temperature (second temperature), thereby forming the SiN film 106 in which the seed layer 104 and the bulk layer 105 are laminated. The seed layer 104 formed in a state where the surface of the Ru film 103 is exposed is formed at a low temperature, so that the silicidation of the Ru film 103 does not easily proceed. In addition, when the bulk layer 105 is formed at a high temperature in a state where the surface of the Ru film 103 is covered with the seed layer 104, the silicidation of the Ru film 103 can be suppressed. In particular, when the thickness of the seed layer 104 is 0.6 nm or more, the silicidation of the Ru film 103 hardly occurs. As a result, the increase in the resistivity of the Ru film 103 can be suppressed.

[0018] [Film forming equipment] The film forming apparatus 1 according to the embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a vertical cross-sectional view showing the film forming apparatus 1 according to the embodiment. Fig. 4 is a horizontal cross-sectional view showing the film forming apparatus 1 according to the embodiment.

[0019] The film forming apparatus 1 includes a processing chamber 10, a gas supply unit 30, an exhaust unit 40, a heating unit 50, a plasma generating mechanism 60, and a control unit 90.

[0020] The processing vessel 10 has a vertical cylindrical shape with a ceiling and an open bottom end. The processing vessel 10 is made of, for example, quartz. A quartz ceiling plate 11 is provided near the upper end of the processing vessel 10, and the area below the ceiling plate 11 is sealed. A cylindrically shaped manifold 12 is connected to the opening at the lower end of the processing vessel 10 via a seal member 13 such as an O-ring. The manifold 12 is made of, for example, metal.

[0021] Manifold 12 supports the lower end of processing vessel 10. Boat 14 is inserted into processing vessel 10 from below manifold 12. Boat 14 holds multiple substrates W at intervals in the vertical direction. Boat 14 holds each substrate W in a horizontal position. Boat 14 is made of, for example, quartz. Boat 14 has, for example, three support columns 15. Each support column 15 has grooves (not shown) formed at predetermined intervals in the vertical direction. Boat 14 holds multiple substrates W by the grooves. The substrates W are, for example, semiconductor wafers.

[0022] The boat 14 is placed on a table 17 via a quartz heat-insulating tube 16. The table 17 is supported on a rotation shaft 19 that penetrates a lid 18. The lid 18 opens and closes the opening at the lower end of the manifold 12. The lid 18 is made of, for example, stainless steel.

[0023] A magnetic fluid seal 20 is provided at the penetration portion of the rotating shaft 19. The magnetic fluid seal 20 airtightly seals the rotating shaft 19 and rotatably supports it. A seal member 21 is provided between the peripheral portion of the lid 18 and the lower end of the manifold 12. The seal member 21 maintains the airtightness inside the processing vessel 10. The seal member 21 is, for example, an O-ring.

[0024] The rotating shaft 19 is attached to the tip of an arm 22 supported by a lifting mechanism (not shown) such as a boat elevator. This allows the boat 14 and the lid 18 to be lifted and lowered as a unit and inserted into and removed from the processing vessel 10.

[0025] An opening 23 and an exhaust port 24 are provided in the side wall of the processing vessel 10. The opening 23 is formed to be elongated in the vertical direction so as to cover all of the substrates W supported by the boat 14 in the vertical direction. The exhaust port 24 is provided, for example, at a position opposite to the opening 23. The exhaust port 24 is formed to be elongated in the vertical direction so as to cover all of the substrates W supported by the boat 14 in the vertical direction.

[0026] The gas supply unit 30 is configured to be able to introduce various process gases used in the above-described film formation method into the process vessel 10. The gas supply unit 30 includes an HCD supply unit 31, a DCS supply unit 32, an ammonia supply unit 33, and a nitrogen supply unit .

[0027] The HCD supply unit 31 includes an HCD supply pipe 31a in the processing vessel 10 and an HCD supply path 31b outside the processing vessel 10. An HCD supply source 31c, a mass flow controller 31d, and a valve 31e are provided in the HCD supply path 31b in this order from the upstream side to the downstream side in the gas flow direction. Thus, the supply timing of the HCD gas from the HCD supply source 31c is controlled by the valve 31e, and the flow rate is adjusted to a predetermined value by the mass flow controller 31d. The HCD gas flows from the HCD supply path 31b into the HCD supply pipe 31a and is discharged from the HCD supply pipe 31a into the processing vessel 10.

[0028] The DCS supply unit 32 includes a DCS supply pipe 32a inside the processing vessel 10, and a DCS supply path 32b outside the processing vessel 10. A DCS source 32c, a mass flow controller 32d, and a valve 32e are provided on the DCS supply path 32b, in this order from the upstream side to the downstream side in the gas flow direction. Thus, the supply timing of the DCS gas from the DCS source 32c is controlled by the valve 32e, and the flow rate is adjusted to a predetermined value by the mass flow controller 32d. The DCS gas flows from the DCS supply path 32b into the DCS supply pipe 32a, and is discharged from the DCS supply pipe 32a into the processing vessel 10.

[0029] The ammonia supply unit 33 includes an ammonia supply pipe 33a inside the processing vessel 10, and an ammonia supply path 33b outside the processing vessel 10. An ammonia source 33c, a mass flow controller 33d, and a valve 33e are provided in the ammonia supply path 33b, in this order from the upstream side to the downstream side in the gas flow direction. Thus, the supply timing of the ammonia gas from the ammonia source 33c is controlled by the valve 33e, and the flow rate is adjusted to a predetermined value by the mass flow controller 33d. The ammonia gas flows from the ammonia supply path 33b into the ammonia supply pipe 33a, and is discharged from the ammonia supply pipe 33a into the processing vessel 10.

[0030] The nitrogen supply unit 34 includes a nitrogen supply pipe 34a inside the processing vessel 10, and a nitrogen supply path 34b outside the processing vessel 10. A nitrogen source 34c, a mass flow controller 34d, and a valve 34e are provided in the nitrogen supply path 34b, in this order from the upstream side to the downstream side in the gas flow direction. Thus, the supply timing of the nitrogen gas from the nitrogen source 34c is controlled by the valve 34e, and the flow rate is adjusted to a predetermined value by the mass flow controller 34d. The nitrogen gas flows from the nitrogen supply path 34b into the nitrogen supply pipe 34a, and is discharged from the nitrogen supply pipe 34a into the processing vessel 10.

[0031] The HCD supply pipe 31a and the DCS supply pipe 32a extend vertically along the inner wall of the processing vessel 10, and are supported so as to penetrate the manifold 12, with their base ends bent in an L shape and extending horizontally. A plurality of HCD outlet ports 31f are provided in the HCD supply pipe 31a at a portion located inside the processing vessel 10. A plurality of DCS outlet ports 32f are provided in the DCS supply pipe 32a at a portion located inside the processing vessel 10.

[0032] The ammonia supply pipe 33a extends vertically along a plasma partition wall 61 in a plasma generation space P described later, and its base end is bent in an L-shape and extends horizontally, and is supported so as to penetrate the manifold 12. A plurality of ammonia discharge ports 33f are provided in a portion of the ammonia supply pipe 33a located inside the processing vessel 10.

[0033] The nitrogen supply pipe 34a extends horizontally inside the processing vessel 10 and is supported so as to penetrate the side wall of the manifold 12. The nitrogen supply pipe 34a has an open end, and discharges nitrogen gas from the opening.

[0034] The HCD supply pipe 31a, the DCS supply pipe 32a, the ammonia supply pipe 33a, and the nitrogen supply pipe 34a are made of, for example, quartz.

[0035] The outlets (HCD outlet 31f, DCS outlet 32f, ammonia outlet 33f) are formed at predetermined intervals along the extension direction of the respective gas supply pipes (HCD supply pipe 31a, DCS supply pipe 32a, ammonia supply pipe 33a). Each outlet discharges gas in the horizontal direction. The interval between each outlet is set to be the same as the interval between the substrates W held in the boat 14, for example. The position of each outlet in the height direction is set to the intermediate position between the substrates W adjacent in the vertical direction. This allows each outlet to efficiently supply gas to the opposing surfaces between the adjacent substrates W.

[0036] The gas supply unit 30 may mix a plurality of types of gases and discharge the mixed gas from one gas supply pipe. The gas supply pipes (HCD supply pipe 31a, DCS supply pipe 32a, ammonia supply pipe 33a, and nitrogen supply pipe 34a) may have different shapes and arrangements. The gas supply unit 30 may include a supply unit that supplies another gas in addition to HCD gas, DCS gas, and ammonia gas.

[0037] The exhaust unit 40 includes a cover member 41, an exhaust pipe 42, a pressure control valve 43, and a vacuum pump 44. The cover member 41 is attached to a portion of the processing vessel 10 corresponding to the exhaust port 24 so as to cover the exhaust port 24. The cover member 41 extends vertically along the outer wall of the processing vessel 10. The exhaust pipe 42 is connected to a lower portion of the cover member 41. The pressure control valve 43 and the vacuum pump 44 are provided on the exhaust pipe 42. The pressure control valve 43 controls the pressure inside the processing vessel 10. The vacuum pump 44 exhausts the inside of the processing vessel 10.

[0038] The heating unit 50 is provided around the processing vessel 10. The heating unit 50 includes, for example, a heater. The heater heats each substrate W in the processing vessel 10 to a predetermined temperature by controlling the output.

[0039] The plasma generation mechanism 60 is provided on a part of the side wall of the processing vessel 10. The plasma generation mechanism 60 generates plasma from the ammonia gas supplied by the ammonia supply pipe 33a. The plasma generation mechanism 60 includes a plasma partition wall 61, a pair of plasma electrodes 62, a power supply line 63, an RF power supply 64, and an insulating protective cover 65.

[0040] The plasma compartment wall 61 is hermetically welded to the outer wall of the processing vessel 10. The plasma compartment wall 61 is made of, for example, quartz. The plasma compartment wall 61 has a concave shape in a horizontal cross section. The plasma compartment wall 61 covers the opening 23. The plasma compartment wall 61 forms a plasma generation space P that communicates with the inside of the processing vessel 10.

[0041] The pair of plasma electrodes 62 each have a shape elongated in the vertical direction. The pair of plasma electrodes 62 are provided on the outer surfaces of the opposing walls of the plasma compartment wall 61. The pair of plasma electrodes 62 are disposed opposite each other across the opposing walls of the plasma compartment wall 61 and the plasma generation space P. A power supply line 63 is connected to the lower end of each plasma electrode 62.

[0042] The power supply line 63 electrically connects each plasma electrode 62 to an RF power supply 64. For example, one end of the power supply line 63 is connected to the lower end of each plasma electrode 62, and the other end is connected to the RF power supply 64.

[0043] The RF power supply 64 is connected to the lower end of each plasma electrode 62 via a power supply line 63. The RF power supply 64 supplies RF power of, for example, 13.56 MHz to the pair of plasma electrodes 62. As a result, the RF power is applied to the plasma generation space P, and plasma is generated from the ammonia gas supplied to the plasma generation space P.

[0044] The insulating protective cover 65 is attached to the outside of the plasma compartment wall 61 so as to cover the plasma compartment wall 61. A coolant passage (not shown) may be provided in the inner portion of the insulating protective cover 65. In this case, the plasma electrode 62 can be cooled by flowing a coolant through the coolant passage.

[0045] The control unit 90 controls the operation of each part of the film forming apparatus 1. The control unit 90 may be, for example, a computer. A computer program for controlling the operation of each part of the film forming apparatus 1 is stored in a storage medium. The storage medium may be, for example, a flexible disk, a compact disk, a hard disk, a flash memory, a DVD, or the like.

[0046] [Operation of the Film Forming Apparatus] The operation of the film forming apparatus 1 when carrying out the film forming method according to the embodiment will be described.

[0047] First, the control unit 90 controls the lifting mechanism (not shown) to load the boat 14 holding the substrates W into the processing vessel 10, and hermetically closes the opening at the bottom of the processing vessel 10 with the lid 18. Next, the control unit 90 controls the exhaust unit 40 to reduce the pressure inside the processing vessel 10. In addition, the control unit 90 controls the heating unit 50 to adjust the temperature of the substrates W to a first temperature (step S2 in FIG. 1). Each substrate W may be the substrate 100 described above.

[0048] Next, the control unit 90 controls the heating unit 50 to maintain the temperature of the substrate W at the first temperature, and controls the gas supply unit 30 to alternately and repeatedly supply the HCD gas and the ammonia gas into the processing vessel 10 (step S3 in FIG. 1). As a result, a seed layer 104 is formed on the Ru film 103 by the thermal ALD method.

[0049] Next, the control unit 90 controls the heating unit 50 to change the temperature of the substrate W from the first temperature to the second temperature (step S4 in FIG. 1).

[0050] Next, the control unit 90 controls the heating unit 50 to maintain the temperature of the substrate W at the second temperature, and controls the gas supply unit 30 to alternately and repeatedly supply DCS gas and ammonia gas into the processing vessel 10 (step S5 in FIG. 1). When supplying ammonia gas into the processing vessel 10, the control unit 90 also controls the RF power supply 64 to supply RF power of, for example, 13.56 MHz to the pair of plasma electrodes 62 to generate plasma from the ammonia gas. As a result, a bulk layer 105 is formed on the seed layer 104 by the plasma ALD method.

[0051] Next, the control unit 90 increases the pressure inside the processing vessel 10 to atmospheric pressure and decreases the temperature inside the processing vessel 10 to the unloading temperature, and then controls the lifting mechanism to unload the boat 14 from the processing vessel 10. In this manner, a SiN film 106 in which a seed layer 104 and a bulk layer 105 are stacked can be formed on the multiple substrates W held in the boat 14.

[0052] [Example] Example 1 First, a substrate was prepared on which a thermal oxide film, a TiN film, and a Ru film were laminated in this order. The prepared substrate was then placed in the processing vessel 10 of the film forming apparatus 1, and a seed layer was formed on the Ru film at different substrate temperatures by the thermal ALD method. The sheet resistance of the Ru film was then measured. For comparison, the sheet resistance of the Ru film before the seed layer was formed was measured. The seed layer was formed under the following conditions.

[0053] (Seed layer formation conditions) Substrate temperature: 400℃, 550℃, 630℃ First silicon-containing gas: HCD gas First nitriding gas: Ammonia gas Seed layer thickness: 0.6 nm

[0054] Fig. 5 is a diagram showing the relationship between the substrate temperature and the sheet resistance of the Ru film. In Fig. 5, the horizontal axis indicates the substrate temperature [°C] when the seed layer is formed, and the vertical axis indicates the sheet resistance [%] of the Ru film. The sheet resistance of the Ru film in Fig. 5 is shown as a relative value when the resistivity of the Ru film before the seed layer is formed is set to 100%.

[0055] As shown in FIG. 5, when the substrate temperature during the seed layer formation was 400° C., 550° C., and 630° C., the sheet resistance of the Ru film was 101%, 105%, and 113%, respectively. From this result, it is considered that the increase in the sheet resistance of the Ru film can be suppressed by setting the substrate temperature during the seed layer formation to 550° C. or less. It is also considered that the increase in the sheet resistance of the Ru film due to the formation of the seed layer can be prevented by setting the substrate temperature during the seed layer formation to 400° C. or less. From the above, it can be said that the substrate temperature during the seed layer formation is preferably 550° C. or less, and more preferably 400° C. or less.

[0056] Example 2 First, a substrate having a trench on its surface, in which a thermal oxide film, a TiN film, and a Ru film were laminated in this order, was prepared. Then, the prepared substrate was placed in the processing vessel 10 of the film forming apparatus 1, and a seed layer of different thicknesses was formed on the Ru film by a thermal ALD method. Then, a bulk layer of different thicknesses was formed on the seed layer by a plasma ALD method. Under each condition, the total thickness of the seed layer and the bulk layer was set to be the same. Then, the wiring resistance of the Ru film was measured. For comparison, the wiring resistance of the Ru film before the formation of the seed layer was measured. The conditions for forming the seed layer and the bulk layer are as follows.

[0057] (Seed layer formation conditions) Substrate temperature: 400℃ First silicon-containing gas: HCD gas First nitriding gas: Ammonia gas Seed layer thickness: 0.4nm, 0.6nm, 0.8nm

[0058] (Conditions for forming bulk layer) Substrate temperature: 630℃ Second silicon-containing gas: DCS gas Second nitriding gas: Ammonia gas Bulk layer thickness: 1.6 nm (seed layer thickness: 0.4 nm) 1.4 nm (when seed layer thickness is 0.6 nm) 1.2 nm (when seed layer thickness is 0.8 nm)

[0059] 6 is a diagram showing the relationship between the thickness of the seed layer and the wiring resistance of the Ru film, in which the wiring resistance of the Ru film in Fig. 6 is shown as a relative value when the wiring resistance of the Ru film before the formation of the seed layer is set to 100%.

[0060] As shown in Figure 6, when the seed layer thickness was 0.4 nm, 0.6 nm, and 0.8 nm, the wiring resistance of the Ru film was 117%, 95%, and 96%, respectively. From this result, it is considered that by making the seed layer thicker than 0.6 nm, it is possible to prevent the increase in the wiring resistance of the Ru film caused by forming the seed layer. For the above reasons, it is preferable that the seed layer thickness is 0.6 nm or more.

[0061] Example 3 First, a substrate was prepared on which a thermal oxide film, a TiN film, and a Ru film were laminated in this order. The prepared substrate was then placed in the processing vessel 10 of the film forming apparatus 1, and a seed layer was formed on the Ru film by a thermal ALD method. Then, a bulk layer was formed on the seed layer by a different deposition method. Then, the sheet resistance of the Ru film was measured. For comparison, the sheet resistance of the Ru film before the formation of the seed layer was measured. The conditions for forming the seed layer and the bulk layer were as follows.

[0062] (Seed layer formation conditions) Substrate temperature: 400℃, 630℃ First silicon-containing gas: HCD gas First nitriding gas: Ammonia gas Seed layer thickness: 0.6 nm

[0063] (Conditions for forming bulk layer) Substrate temperature: 630℃ Second silicon-containing gas: DCS gas, HCD gas Second nitriding gas: Ammonia gas Bulk layer thickness: 1.4 nm Deposition method: PE-DCS (plasma ALD method, second silicon-containing gas: DCS gas) Th-DCS (Thermal ALD: Second silicon-containing gas: DCS gas) Th-HCD (Thermal ALD: Second silicon-containing gas: HCD gas)

[0064] FIG. 7 is a diagram showing the relationship between the deposition method of the bulk layer and the sheet resistance of the Ru film. The sheet resistance of the Ru film in FIG. 7 is shown as a relative value when the sheet resistance of the Ru film before the formation of the seed layer is set to 100%. In FIG. 7, the leftmost bar graph shows the result of forming a bulk layer by a plasma ALD method (PE-DCS) using DCS gas as the second silicon-containing gas. The second bar graph from the left shows the result of forming a bulk layer by a thermal ALD method (Th-DCS) using DCS gas as the second silicon-containing gas. The third bar graph from the left shows the result of forming a bulk layer by a thermal ALD method (Th-HCD) using HCD gas as the second silicon-containing gas. The rightmost bar graph shows the result when the substrate temperature when forming the seed layer is changed from 400° C. to 630° C. compared to the leftmost bar graph.

[0065] As shown in Figure 7, when the seed layer was formed at a substrate temperature of 400°C, the sheet resistance of the Ru film was 102%, regardless of the deposition method of the bulk layer formed on the seed layer. From this result, it is considered that when the seed layer is formed at a substrate temperature of 400°C, the increase in the sheet resistance of the Ru film can be suppressed even if the deposition method of the bulk layer is changed.

[0066] Example 4 First, a substrate was prepared on which a thermal oxide film, a TiN film, and a Ru film were laminated in this order. The prepared substrate was then placed in the processing chamber 10 of the film formation apparatus 1, and a seed layer was formed on the Ru film at different substrate temperatures by a thermal ALD method. Then, a bulk layer was formed on the seed layer by a plasma ALD method. Then, a cross section of the substrate was observed by a transmission electron microscope (TEM). The seed layer and bulk layer were formed under the following conditions.

[0067] (Seed layer formation conditions) Substrate temperature: 400℃, 630℃ First silicon-containing gas: HCD gas First nitriding gas: Ammonia gas Seed layer thickness: 0.6 nm

[0068] (Conditions for forming bulk layer) Substrate temperature: 630℃ Second silicon-containing gas: DCS gas Second nitriding gas: Ammonia gas Bulk layer thickness: 1.4 nm

[0069] 8 and 9 are diagrams showing the interface state between the Ru film and the SiN film. Fig. 8 is a cross-sectional TEM image of the substrate when the seed layer is formed at a substrate temperature of 400° C. Fig. 9 is a cross-sectional TEM image of the substrate when the seed layer is formed at a substrate temperature of 630° C.

[0070] As shown in Fig. 8, when the seed layer is formed at a substrate temperature of 400°C, the silicon (Si) atoms contained in the SiN film (a laminate of the seed layer and the bulk layer) hardly diffuse into the Ru film. In contrast, as shown in Fig. 9, when the seed layer is formed at a substrate temperature of 630°C, the silicon (Si) atoms contained in the SiN film (a laminate of the seed layer and the bulk layer) diffuse into the Ru film. From this result, it is considered that by forming a seed layer at a substrate temperature of 400°C before forming a bulk layer on the Ru film, the diffusion of the silicon (Si) atoms contained in the SiN film into the Ru film can be suppressed, and the resistance of the Ru film can be suppressed.

[0071] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0072] In the above embodiment, the first silicon-containing gas is HCD gas and the second silicon-containing gas is DCS gas, but the present disclosure is not limited thereto. For example, the first silicon-containing gas and the second silicon-containing gas can be selected from MCS (monochlorosilane), DCS (dichlorosilane) gas, TCS (trichlorosilane) gas, hexachlorodisilane (HCD) gas, TSA (trisilylamine) gas, or a combination thereof.

[0073] In the above embodiment, the first nitriding gas and the second nitriding gas are ammonia gas, but the present disclosure is not limited thereto. For example, the first nitriding gas and the second nitriding gas may be different gases. For example, the first nitriding gas and the second nitriding gas may be ammonia (NH3) gas, diazane (N2H2) gas, hydrazine (N2H4) gas, monomethylhydrazine (CH3(NH)NH2) gas, or a combination thereof, respectively.

[0074] In the above embodiment, the film containing silicon atoms and nitrogen atoms is a silicon nitride film, but the present disclosure is not limited thereto. For example, the film containing silicon atoms and nitrogen atoms may contain another element. For example, the film containing silicon atoms and nitrogen atoms may be a low-k film such as a SiCN film, a SiON film, a SiOCN film, a SiBN film, or a SiBCN film.

[0075] In the above embodiment, the metal film is a Ru film, but the present disclosure is not limited to this. For example, the metal film may be a tungsten (W) film, a cobalt (Co) film, or a molybdenum (Mo) film.

[0076] In the above embodiment, the seed layer is formed by the thermal ALD method, but the present disclosure is not limited thereto. For example, the seed layer may be formed by the plasma ALD method. For example, the seed layer may be formed by the chemical vapor deposition (CVD) method. The CVD method may be the thermal CVD method or the plasma CVD method.

[0077] In the above embodiment, the bulk layer is formed by the plasma ALD method, but the present disclosure is not limited thereto. For example, the bulk layer may be formed by the thermal ALD method. For example, the bulk layer may be formed by the CVD method. The CVD method may be the thermal CVD method or the plasma CVD method.

[0078] In the above embodiment, the film forming apparatus is a capacitively coupled plasma (CCP) apparatus, but the present disclosure is not limited thereto. For example, the film forming apparatus may be an inductively coupled plasma (ICP) apparatus, a remote plasma apparatus, or a microwave plasma apparatus.

[0079] In the above embodiment, the film forming apparatus is a batch type apparatus that processes a plurality of substrates at once, but the present disclosure is not limited to this. For example, the film forming apparatus may be a semi-batch type apparatus that rotates a plurality of substrates placed on a turntable in a processing vessel by the turntable and passes the substrates through a plurality of processing regions in order to process the substrates. For example, the film forming apparatus may be a single-wafer type apparatus that processes substrates one by one. [Explanation of symbols]

[0080] 100 Substrates 103 Ru membrane 104 Seed layer 105 Bulk layer

Claims

1. 1. A method for forming a film containing silicon atoms and nitrogen atoms on a surface of a substrate having a metal film on the surface, comprising the steps of: supplying a first silicon-containing gas and a first nitriding gas to the substrate while maintaining the substrate at a first temperature, to form a seed layer containing silicon atoms and nitrogen atoms on the surface; supplying a second silicon-containing gas and a second nitriding gas to the substrate while maintaining the substrate at a second temperature higher than the first temperature to form a bulk layer containing silicon atoms and nitrogen atoms on the seed layer; The film forming method includes the steps of:

2. The seed layer has a thickness less than the thickness of the bulk layer. The film forming method according to claim 1 .

3. The thickness of the seed layer is 0.6 nm or more. The film forming method according to claim 1 .

4. The first temperature is 550° C. or less. The film forming method according to claim 1 .

5. The step of forming the seed layer includes forming the seed layer by a thermal ALD method in which the supply of the first silicon-containing gas and the supply of the first nitriding gas are alternately repeated. The film forming method according to claim 1 .

6. The step of forming the bulk layer includes forming the bulk layer by a plasma ALD method in which the supply of the second silicon-containing gas and the exposure to plasma generated from the second nitriding gas are alternately repeated. The film forming method according to claim 1 .

7. the second silicon-containing gas is a gas different from the first silicon-containing gas; The film forming method according to claim 1 .

8. the first silicon-containing gas is hexachlorodisilane gas; The second silicon-containing gas is dichlorosilane gas. The film forming method according to claim 1 .

9. The metal film is a ruthenium film. The film forming method according to claim 1 .

10. A film forming apparatus for forming a film containing silicon atoms and nitrogen atoms on a surface of a substrate having a metal film on the surface, the apparatus comprising: a processing vessel for accommodating the substrate; a gas supply unit for supplying a gas into the processing chamber; a heating unit that heats the substrate accommodated in the processing vessel; A control unit; Equipped with The control unit is supplying a first silicon-containing gas and a first nitriding gas to the substrate while maintaining the substrate at a first temperature, to form a seed layer containing silicon atoms and nitrogen atoms on the surface; supplying a second silicon-containing gas and a second nitriding gas to the substrate while maintaining the substrate at a second temperature higher than the first temperature to form a bulk layer containing silicon atoms and nitrogen atoms on the seed layer; configured to: Film deposition equipment.

Images