Film forming method and film forming apparatus

Abstract

The present disclosure provides a film forming method and a film forming apparatus capable of suppressing an increase in resistivity of a metal film when forming a film containing silicon atoms and nitrogen atoms on the metal film. A film forming method according to one embodiment of the present disclosure is 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, the film forming method including: supplying a first silicon-containing gas and a first nitriding gas to the substrate while maintaining the substrate at a first temperature; forming a seed crystal layer containing silicon atoms and nitrogen atoms on the surface; and forming a bulk layer including 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 higher than the first temperature.

Description

Technical Field

[0001] The present disclosure relates to a film forming method and a film forming device. Background Art

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

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-29582 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] The present disclosure provides a technology capable of suppressing an increase in the resistivity of a metal film when a film including silicon atoms and nitrogen atoms is formed on a metal film.

[0008] Solutions for solving problems

[0009] A film forming method based on one embodiment of the present disclosure is a method for forming a film containing silicon atoms and nitrogen atoms on the surface of a substrate having a metal film on the surface, the film forming method comprising the following steps: supplying a first silicon-containing gas and a first nitride 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 nitride 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.

[0010] Effects of the Invention

[0011] According to the present disclosure, when a film including silicon atoms and nitrogen atoms is formed on a metal film, an increase in the resistivity of the metal film can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 1 is a flowchart showing a film forming method according to an embodiment.

[0013] Figure 2 It is a cross-sectional view showing a film forming method according to an embodiment.

[0014] Figure 3It is a vertical cross-sectional view showing a film forming apparatus according to an embodiment.

[0015] Figure 4 It is a horizontal cross-sectional view showing a film forming apparatus according to an embodiment.

[0016] Figure 5 is a graph showing the relationship between substrate temperature and sheet resistance of the Ru film.

[0017] Figure 6 : is a graph showing the relationship between the thickness of the seed layer and the wiring resistance of the Ru film.

[0018] Figure 7 : is a graph showing the relationship between the deposition method of the bulk layer and the sheet resistance of the Ru film.

[0019] Figure 8 It is a diagram showing the interface state between the Ru film and the SiN film.

[0020] Fig. 9 It is a diagram showing the interface state between the Ru film and the SiN film. DETAILED DESCRIPTION

[0021] Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the attached drawings. In all the attached drawings, the same or corresponding components or parts are marked with the same or corresponding reference numerals, and repeated descriptions are omitted.

[0022] [Film forming method]

[0023] Reference Figure 1 and Figure 2 , to illustrate the film forming method involved in the embodiment. Figure 1 1 is a flowchart showing a film forming method according to an embodiment. Figure 2 2 is a cross-sectional view showing a film forming method according to an embodiment of the present invention. In the embodiment, a case where a silicon nitride (SiN) film as an example of a film containing silicon (Si) atoms and nitrogen (N) atoms is formed on a ruthenium (Ru) film as an example of a metal film is described as an example.

[0024] In step S1, Figure 2As shown in (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 disposed on the insulating film 101. The barrier metal film 102 is, for example, a titanium nitride (TiN) film. The Ru film 103 is disposed on the barrier metal film 102. The Ru film 103 is, for example, formed by a physical vapor deposition (PVD: Physical Vapor Deposition) method. The Ru film 103 can be heat-treated in a reduced pressure atmosphere maintained at a temperature of more than 600° C. and less than 700° C. or in an inert gas atmosphere. In this case, the grain size (particle size) of the Ru film 103 can be enlarged to reduce the resistivity.

[0025] 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 container, and the processing container is heated by a heater so that the temperature of the substrate 100 becomes a first temperature. The first temperature is, for example, 550° C. or less. 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 not easy to increase.

[0026] Step S3 is performed after step S2. In step S3, while the temperature of the substrate 100 is maintained at the first temperature, Figure 2 As shown in (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, for example, by a thermal ALD method in which a first silicon-containing gas is repeatedly and alternately supplied to the substrate 100 and a first nitriding gas is supplied to the substrate 100. In this case, it is easy to conformally form the seed layer 104 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, greater than 0.6 nm. In this case, even if the Ru film 103 is exposed to high temperature in step S3, the resistivity of the Ru film 103 is not easy to increase.

[0027] 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 a temperature higher than the first temperature. The second temperature is, for example, 600° C. or higher. In this case, a high-quality bulk layer 105 is easily formed in step S5.

[0028] Step S5 is performed after step S4. In step S5, while the temperature of the substrate 100 is maintained at the second temperature, Figure 2As shown in (c), a bulk layer 105 is formed on the seed layer 104. The bulk layer 105 can be formed, for example, by a plasma ALD method in which a second silicon-containing gas is repeatedly and alternately supplied to the substrate 100 and the substrate 100 is exposed to a plasma generated from a second nitriding gas. In this case, a high-quality bulk layer 105 can be conformally formed 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.

[0029] Through the above steps S1 to S5 , the SiN film 106 in which the seed layer 104 and the bulk layer 105 are stacked can be formed on the Ru film 103 .

[0030] When the SiN film 106 is formed on the Ru film 103 at a high temperature, silicon (Si) atoms contained in the SiN film 106 diffuse into the Ru film 103 to form 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.

[0031] In the film forming method involved in the embodiment, a seed layer 104 is formed on the Ru film 103 at a low temperature (first temperature), and then a bulk layer 105 is formed at a high temperature (second temperature), thereby forming a SiN film 106 in which the seed layer 104 and the bulk layer 105 are stacked. The seed layer 104 formed in a state where the surface of the Ru film 103 is exposed is a low-temperature film, so the silicide of the Ru film 103 is not easy to progress. In addition, in the case where the bulk layer 105 is formed at a high temperature in a state where the surface of the Ru film 103 is covered by the seed layer 104, the silicide of the Ru film 103 can be suppressed. In particular, when the thickness of the seed layer 104 is 0.6nm or more, the silicide of the Ru film 103 hardly occurs. As a result, the increase in the resistivity of the Ru film 103 can be suppressed.

[0032] 〔Film forming device〕

[0033] Reference Figure 3 and Figure 4 A film forming apparatus 1 according to the embodiment will be described. Figure 3 It is a vertical cross-sectional view showing the film forming apparatus 1 according to the embodiment. Figure 4 It is a horizontal cross-sectional view showing the film forming apparatus 1 according to the embodiment.

[0034] The film forming apparatus 1 includes a processing container 10 , a gas supply unit 30 , an exhaust unit 40 , a heating unit 50 , a plasma generating mechanism 60 , and a control unit 90 .

[0035] The processing container 10 has a vertical cylindrical shape with a top and an open lower end. The processing container 10 is formed of, for example, quartz. A quartz top plate 11 is provided near the upper end of the processing container 10, and the area below the top plate 11 is sealed. A manifold 12 formed in a cylindrical shape is connected to the opening at the lower end of the processing container 10 via a sealing member 13 such as an O-ring. The manifold 12 is formed of, for example, metal.

[0036] The manifold 12 supports the lower end of the processing container 10. The wafer boat 14 is inserted into the processing container 10 from the bottom of the manifold 12. The wafer boat 14 holds a plurality of substrates W in a manner with intervals in the up-down direction. The wafer boat 14 holds each substrate W in a horizontal posture. The wafer boat 14 is formed of, for example, quartz. The wafer boat 14 has, for example, three pillars 15. A groove (not shown) is formed in each pillar 15 at a predetermined interval in the up-down direction. The wafer boat 14 holds a plurality of substrates W through the grooves. The substrate W is, for example, a semiconductor wafer.

[0037] The wafer boat 14 is placed on a stage 17 via a quartz heat-insulating cylinder 16. The stage 17 is supported by a rotating shaft 19 that passes through a cover 18. The cover 18 opens and closes the opening at the lower end of the manifold 12. The cover 18 is made of, for example, stainless steel.

[0038] A magnetic fluid seal 20 is provided at the through portion of the rotating shaft 19. The magnetic fluid seal 20 hermetically seals the rotating shaft 19 and rotatably supports the rotating shaft 19. A sealing member 21 is provided between the peripheral portion of the cover 18 and the lower end of the manifold 12. The sealing member 21 maintains the airtightness in the processing container 10. The sealing member 21 is, for example, an O-ring.

[0039] The rotating shaft 19 is attached to the front end of an arm 22 supported by a lifting mechanism (not shown) such as a wafer boat lift, etc. Thus, the wafer boat 14 and the cover 18 are lifted and lowered as a whole, and inserted and removed from the processing container 10.

[0040] An opening 23 and an exhaust port 24 are provided on the side wall of the processing container 10. The opening 23 is formed to be vertically elongated so as to cover all the substrates W supported on the wafer boat 14 in the vertical direction. The exhaust port 24 is provided, for example, at a position facing the opening 23. The exhaust port 24 is formed to be vertically elongated so as to cover all the substrates W supported on the wafer boat 14 in the vertical direction.

[0041] The gas supply unit 30 is configured to be able to introduce various process gases used in the above-described film forming method into the process container 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 34.

[0042] The HCD supply unit 31 is provided with an HCD supply pipe 31a in the processing container 10, and an HCD supply path 31b outside the processing container 10. In the HCD supply path 31b, an HCD supply source 31c, a mass flow controller 31d, and a valve 31e are sequentially arranged from the upstream side to the downstream side of the flow direction of the gas. Thus, the supply timing of the HCD gas of the HCD supply source 31c is controlled by the valve 31e, and the HCD gas is adjusted to a specified flow rate by the mass flow controller 31d. The HCD gas flows from the HCD supply path 31b into the HCD supply pipe 31a, and is ejected from the HCD supply pipe 31a into the processing container 10.

[0043] The DCS supply unit 32 includes a DCS supply pipe 32a in the processing container 10 and a DCS supply path 32b outside the processing container 10. In the DCS supply path 32b, a DCS source 32c, a mass flow controller 32d, and a valve 32e are sequentially arranged from the upstream side to the downstream side in the flow direction of the gas. Thus, the supply timing of the DCS gas of the DCS source 32c is controlled by the valve 32e, and the DCS gas is adjusted to a specified flow rate by the mass flow controller 32d. The DCS gas flows from the DCS supply path 32b into the DCS supply pipe 32a, and is ejected from the DCS supply pipe 32a into the processing container 10.

[0044] The ammonia supply unit 33 includes an ammonia supply pipe 33a in the processing container 10 and an ammonia supply path 33b outside the processing container 10. In the ammonia supply path 33b, an ammonia source 33c, a mass flow controller 33d, and a valve 33e are sequentially arranged from the upstream side to the downstream side in the flow direction of the gas. Thus, the ammonia gas of the ammonia source 33c is controlled to be supplied at a timing by the valve 33e, and is adjusted to a predetermined flow rate by the mass flow controller 33d. Ammonia gas flows from the ammonia supply path 33b into the ammonia supply pipe 33a, and is ejected from the ammonia supply pipe 33a into the processing container 10.

[0045] The nitrogen supply unit 34 includes a nitrogen supply pipe 34a in the processing container 10 and a nitrogen supply path 34b outside the processing container 10. In the nitrogen supply path 34b, a nitrogen source 34c, a mass flow controller 34d, and a valve 34e are sequentially arranged from the upstream side to the downstream side in the flow direction of the gas. Thus, the nitrogen gas of the nitrogen source 34c is controlled to be supplied at a timing by the valve 34e, and is adjusted to a predetermined flow rate by the mass flow controller 34d. The nitrogen gas flows from the nitrogen supply path 34b into the nitrogen supply pipe 34a, and is ejected from the nitrogen supply pipe 34a into the processing container 10.

[0046] The HCD supply pipe 31a and the DCS supply pipe 32a are supported to extend vertically along the inner wall of the processing container 10, and the base ends are bent into an L-shape and extend horizontally to penetrate the manifold 12. A plurality of HCD discharge ports 31f are provided at a portion of the HCD supply pipe 31a located in the processing container 10. A plurality of DCS discharge ports 32f are provided at a portion of the DSC supply pipe 32a located in the processing container 10.

[0047] The ammonia supply pipe 33a is supported to extend vertically along the plasma partition wall 61 in the plasma generation space P described later, and its base end is bent into an L-shape to extend horizontally and penetrate the manifold 12. A plurality of ammonia ejection ports 33f are provided at a portion of the ammonia supply pipe 33a located in the processing container 10.

[0048] The nitrogen supply pipe 34a is supported so as to extend horizontally in the processing container 10 and penetrate the side wall of the manifold 12. The nitrogen supply pipe 34a has an opening at the front end, and nitrogen gas is ejected from the opening.

[0049] The HCD supply pipe 31 a , the DCS supply pipe 32 a , the ammonia supply pipe 33 a , and the nitrogen supply pipe 34 a are formed of, for example, quartz.

[0050] Each nozzle (HCD nozzle 31f, DCS nozzle 32f, ammonia nozzle 33f) is formed at a predetermined interval along the extension direction of each gas supply pipe (HCD supply pipe 31a, DCS supply pipe 32a, ammonia supply pipe 33a). Each nozzle releases gas in a horizontal direction. The interval between each nozzle is set to be the same as the interval between substrates W held on the wafer boat 14, for example. The position of each nozzle in the height direction is set to the middle position between adjacent substrates W in the vertical direction. Thus, each nozzle can efficiently supply gas to the facing surfaces between adjacent substrates W.

[0051] Alternatively, the gas supply unit 30 mixes a plurality of gases and ejects the mixed gas from one gas supply pipe. The gas supply pipes (HCD supply pipe 31a, DCS supply pipe 32a, ammonia supply pipe 33a, nitrogen supply pipe 34a) may have different shapes and configurations. The gas supply unit 30 may include a supply unit for supplying other gases in addition to HCD gas, DCS gas, and ammonia gas.

[0052] 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 installed at a portion corresponding to the exhaust port 24 of the processing container 10 in a manner covering the exhaust port 24. The cover member 41 extends vertically along the outer wall of the processing container 10. The exhaust pipe 42 is connected to the 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 in the processing container 10. The vacuum pump 44 exhausts the processing container 10.

[0053] The heating unit 50 is provided around the processing container 10. The heating unit 50 includes, for example, a heater. The heater heats each substrate W in the processing container 10 to a predetermined temperature by controlling the output of the heater.

[0054] The plasma generating mechanism 60 is provided at a part of the side wall of the processing chamber 10. The plasma generating mechanism 60 generates plasma from the ammonia gas supplied from the ammonia supply pipe 33a. The plasma generating mechanism 60 includes a plasma partitioning wall 61, a pair of plasma electrodes 62, a power supply line 63, an RF power supply 64, and an insulating protective cover 65.

[0055] The plasma partition wall 61 is welded to the outer wall of the processing container 10 in an airtight manner. The plasma partition wall 61 is formed of, for example, quartz. The plasma partition wall 61 has a concave shape in a horizontal cross section. The plasma partition wall 61 covers the opening 23. The plasma partition wall 61 forms a plasma generation space P communicating with the inside of the processing container 10.

[0056] The pair of plasma electrodes 62 each have a vertically elongated shape. The pair of plasma electrodes 62 are provided on the outer surfaces of the opposing walls of the plasma partitioning wall 61. The pair of plasma electrodes 62 are arranged to face each other in a manner of sandwiching the opposing walls of the plasma partitioning wall 61 and the plasma generation space P. A power supply line 63 is connected to the lower end of each plasma electrode 62.

[0057] The power supply line 63 electrically connects each plasma electrode 62 and the 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.

[0058] 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 13.56 MHz RF power to the pair of plasma electrodes 62. Thus, 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.

[0059] The insulating protective cover 65 is installed on the outer side of the plasma partitioning wall 61 so as to cover the plasma partitioning wall 61. A refrigerant passage (not shown) may be provided inside the insulating protective cover 65. In this case, the plasma electrode 62 can be cooled by flowing the refrigerant in the refrigerant passage.

[0060] The control unit 90 controls the operation of each unit of the film forming apparatus 1. The control unit 90 may be, for example, a computer. A computer program for operating each unit of the film forming apparatus 1 is stored in a storage medium. The storage medium may be, for example, a floppy disk, an optical disk, a hard disk, a flash memory, a DVD, or the like.

[0061] [Operation of film forming device]

[0062] The operation when the film forming method according to the embodiment is performed in the film forming apparatus 1 will be described.

[0063] First, the control unit 90 controls the lifting mechanism (not shown) to move the wafer boat 14 holding a plurality of substrates W into the processing container 10, and seals the lower opening of the processing container 10 by the cover 18. Next, the control unit 90 controls the exhaust unit 40 to reduce the pressure in the processing container 10. In addition, the control unit 90 controls the heating unit 50 to adjust the temperature of the substrate W to the first temperature ( Figure 1 Step S2). Each substrate W may be the substrate 100 described above.

[0064] 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 repeatedly and alternately supply the HCD gas and the ammonia gas into the processing container 10 ( Figure 1 Thus, the seed layer 104 is formed on the Ru film 103 by the thermal ALD method.

[0065] 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 ( Figure 1 Step S4).

[0066] 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 repeatedly and alternately supply the DCS gas and the ammonia gas into the processing container 10 ( Figure 1 In addition, the control unit 90 controls the RF power supply 64 to supply 13.56 MHz RF power to the pair of plasma electrodes 62 when supplying ammonia gas into the processing container 10, thereby generating plasma from the ammonia gas. Thus, the bulk layer 105 is formed on the seed layer 104 by the plasma ALD method.

[0067] Next, the control unit 90 increases the pressure in the processing container 10 to the atmospheric pressure and cools the temperature in the processing container 10 to the carrying-out temperature, and then controls the lifting mechanism to carry the wafer boat 14 out of the processing container 10. Through the above actions, the SiN film 106 formed by stacking the seed layer 104 and the bulk layer 105 can be formed on the plurality of substrates W held in the wafer boat 14.

[0068] [Example]

[0069] (Example 1)

[0070] First, a substrate on which a thermal oxide film, a TiN film, and a Ru film are sequentially stacked is prepared. Next, the prepared substrate is accommodated in a processing container 10 of a film forming apparatus 1, and a seed layer is formed on the Ru film at different substrate temperatures by a thermal ALD method. Next, the sheet resistance of the Ru film is measured. For comparison, the sheet resistance of the Ru film before the seed layer is formed is measured. The formation conditions of the seed layer are as follows.

[0071] (Seed Layer Formation Conditions)

[0072] Substrate temperature: 400°C, 550°C, 630°C

[0073] The first silicon-containing gas: HCD gas

[0074] First nitriding gas: ammonia

[0075] Thickness of seed layer: 0.6nm

[0076] Figure 5 is a graph showing the relationship between substrate temperature and sheet resistance of the Ru film. Figure 5 In the graph, the horizontal axis represents the substrate temperature [° C.] when the seed layer is formed, and the vertical axis represents the sheet resistance [%] of the Ru film. Figure 5 The sheet resistance of the Ru film in φ is expressed as a relative value when the resistivity of the Ru film before forming the seed layer is set to 100%.

[0077] like Figure 5 As shown in the figure, when the substrate temperature when forming the seed layer is 400°C, 550°C, and 630°C, the sheet resistance of the Ru film is 101%, 105%, and 113%, respectively. Based on this result, it is believed that by setting the substrate temperature when forming the seed layer to 550°C or less, the increase in the sheet resistance of the Ru film can be suppressed. In addition, it is believed that by setting the substrate temperature when forming the seed layer to 400°C or less, the increase in the sheet resistance of the Ru film caused by the formation of the seed layer can be prevented. Based on the above, it can be said that the substrate temperature when forming the seed layer is preferably 550°C or less, and more preferably 400°C or less.

[0078] (Example 2)

[0079] First, a substrate having grooves on the surface and stacked with a thermal oxide film, a TiN film, and a Ru film in sequence is prepared. Next, the prepared substrate is placed in a processing container 10 of a film forming device 1, and a seed layer of different thicknesses is formed on the Ru film by a thermal ALD method. Next, a bulk layer of different thicknesses is formed on the seed layer by a plasma ALD method. It is assumed that the total thickness of the seed layer and the thickness of the bulk layer are the same under each condition. Next, the wiring resistance of the Ru film is measured. For comparison, the wiring resistance of the Ru film before the seed layer is formed is measured. The formation conditions of the seed layer and the formation conditions of the bulk layer are as follows.

[0080] (Seed Layer Formation Conditions)

[0081] Substrate temperature: 400°C

[0082] The first silicon-containing gas: HCD gas

[0083] First nitriding gas: ammonia

[0084] Seed layer thickness: 0.4nm, 0.6nm, 0.8nm

[0085] (Conditions for formation of body layer)

[0086] Substrate temperature: 630°C

[0087] The second silicon-containing gas: DCS gas

[0088] Second nitriding gas: ammonia

[0089] Thickness of bulk layer: 1.6 nm (when the thickness of seed layer is 0.4 nm)

[0090] 1.4nm (when the seed layer thickness is 0.6nm)

[0091] 1.2nm (when the seed layer thickness is 0.8nm)

[0092] Figure 6 : is a graph showing the relationship between the thickness of the seed layer and the wiring resistance of the Ru film. Figure 6 The wiring resistance of the Ru film in is expressed as a relative value when the wiring resistance of the Ru film before forming the seed layer is set to 100%.

[0093] like Figure 6As shown in the figure, when the thickness of the seed layer is 0.4nm, 0.6nm, and 0.8nm, the wiring resistance of the Ru film is 117%, 95%, and 96%, respectively. Based on this result, it is believed that by setting the thickness of the seed layer to be greater than 0.6nm, the increase in the wiring resistance of the Ru film caused by the formation of the seed layer can be prevented. Based on the above, the thickness of the seed layer is preferably greater than 0.6nm.

[0094] (Example 3)

[0095] First, a substrate on which a thermal oxide film, a TiN film, and a Ru film are stacked in sequence is prepared. Next, the prepared substrate is accommodated in a processing container 10 of a film forming apparatus 1, and a seed layer is formed on the Ru film by a thermal ALD method. Next, a bulk layer is formed on the seed layer by different deposition methods. Next, the sheet resistance of the Ru film is measured. For comparison, the sheet resistance of the Ru film before the seed layer is formed is measured. The formation conditions of the seed layer and the formation conditions of the bulk layer are as follows.

[0096] (Seed Layer Formation Conditions)

[0097] Substrate temperature: 400°C, 630°C

[0098] The first silicon-containing gas: HCD gas

[0099] First nitriding gas: ammonia

[0100] Thickness of seed layer: 0.6nm

[0101] (Conditions for formation of body layer)

[0102] Substrate temperature: 630°C

[0103] Second silicon-containing gas: DCS gas, HCD gas

[0104] Second nitriding gas: ammonia

[0105] Thickness of the bulk layer: 1.4nm

[0106] Deposition method: PE-DCS (plasma ALD method, second silicon-containing gas: DCS gas)

[0107] Th-DCS (thermal ALD method, second silicon-containing gas: DCS gas)

[0108] Th-HCD (thermal ALD method, second silicon-containing gas: HCD gas)

[0109] Figure 7 : is a graph showing the relationship between the deposition method of the bulk layer and the sheet resistance of the Ru film. Figure 7The sheet resistance of the Ru film in is expressed as a relative value when the sheet resistance of the Ru film before forming the seed layer is set to 100%. Figure 7 , the leftmost bar graph shows the results obtained by 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 results obtained by 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 results obtained by 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 results when the substrate temperature when forming the seed layer is changed from 400°C to 630°C relative to the leftmost bar graph.

[0110] like Figure 7 As shown in FIG. 1 , when the seed layer is formed at a substrate temperature of 400° C., the sheet resistance of the Ru film is 102% regardless of the difference in the deposition method of the bulk layer formed on the seed layer. Based on 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.

[0111] (Example 4)

[0112] First, a substrate on which a thermal oxide film, a TiN film, and a Ru film are stacked in sequence is prepared. Next, the prepared substrate is placed in a processing container 10 of a film forming apparatus 1, and a seed layer is formed on the Ru film at different substrate temperatures by a thermal ALD method. Next, a bulk layer is formed on the seed layer by a plasma ALD method. Next, a cross section of the substrate is observed using a transmission electron microscope (TEM). The formation conditions of the seed layer and the formation conditions of the bulk layer are as follows.

[0113] (Seed Layer Formation Conditions)

[0114] Substrate temperature: 400°C, 630°C

[0115] The first silicon-containing gas: HCD gas

[0116] First nitriding gas: ammonia

[0117] Thickness of seed layer: 0.6nm

[0118] (Conditions for formation of body layer)

[0119] Substrate temperature: 630°C

[0120] The second silicon-containing gas: DCS gas

[0121] Second nitriding gas: ammonia

[0122] Thickness of the bulk layer: 1.4nm

[0123] Figure 8 and Fig. 9 It is a diagram showing the interface state between the Ru film and the SiN film. Figure 8 This is a cross-sectional TEM image of a substrate when a seed layer is formed at a substrate temperature of 400°C. Fig. 9 This is a cross-sectional TEM picture of a substrate when a seed layer is formed at a substrate temperature of 630°C.

[0124] like Figure 8 As shown in FIG. 1 , when the seed layer is formed at a substrate temperature of 400° C., diffusion of silicon (Si) atoms contained in the SiN film (stacked body of the seed layer and the bulk layer) into the Ru film is hardly observed. Fig. 9 As shown in the figure, when the seed layer is formed at a substrate temperature of 630°C, silicon (Si) atoms contained in the SiN film (stacked body of the seed layer and the bulk layer) diffuse into the Ru film. Based on this result, it is believed that by setting the substrate temperature to 400°C to form the seed layer before forming the bulk layer on the Ru film, the diffusion of silicon (Si) atoms contained in the SiN film into the Ru film can be suppressed, thereby suppressing the high resistance of the Ru film.

[0125] The embodiments disclosed herein are illustrative in all respects and should not be construed as limiting. The embodiments described above may be omitted, replaced, or modified in various ways without departing from the appended claims and the gist thereof.

[0126] In the above-mentioned 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 (triallylamine) gas, or a combination thereof.

[0127] In the above-mentioned embodiment, the first nitriding gas and the second nitriding gas are described as ammonia gas, but the present disclosure is not limited thereto. For example, the first nitriding gas and the second nitriding gas may also be different gases. For example, the first nitriding gas and the second nitriding gas may respectively utilize ammonia (NH3) gas, diimide (N2H2) gas, hydrazine (N2H4) gas, monomethylhydrazine (CH3(NH)NH2) gas, or a combination thereof.

[0128] In the above-mentioned 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 also contain other elements. For example, the film containing silicon atoms and nitrogen atoms may also be a Low-k (low dielectric constant) film such as a SiCN film, a SiON film, a SiOCN film, a SiBN film, or a SiBCN film.

[0129] In the above-mentioned embodiment, the case where the metal film is a Ru film is described, but the present disclosure is not limited thereto. For example, the metal film may be a tungsten (W) film, a cobalt (Co) film, or a molybdenum (Mo) film.

[0130] In the above-mentioned embodiment, the case where the seed layer is formed by the thermal ALD method is described, but the present disclosure is not limited thereto. For example, the seed layer may be formed by a plasma ALD method. For example, the seed layer may be formed by a chemical vapor deposition (CVD) method. The CVD method may be a thermal CVD method or a plasma CVD method.

[0131] In the above-mentioned embodiment, the case where the bulk layer is formed by the plasma ALD method is described, 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 a thermal CVD method or a plasma CVD method.

[0132] In the above embodiment, the film forming apparatus is described as 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.

[0133] In the above-mentioned embodiment, the film forming apparatus is described as a batch type apparatus that processes a plurality of substrates at the same time, but the present disclosure is not limited thereto. For example, the film forming apparatus may also be a semi-batch type apparatus that uses a rotating table in a processing container to make a plurality of substrates disposed on a rotating table revolve, and sequentially passes through a plurality of processing areas to process the substrates. For example, the film forming apparatus may also be a single-wafer type apparatus that processes substrates one by one.

[0134] Description of Reference Numerals

[0135] 100: substrate; 103: Ru film; 104: seed layer; 105: bulk layer.

Claims

1. A film forming 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 film forming method comprising the following steps: 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 A second silicon-containing gas and a second nitriding gas are supplied to the substrate while the substrate is maintained at a second temperature higher than the first temperature, so as to form a bulk layer including silicon atoms and nitrogen atoms on the seed layer.

2. The film forming method according to claim 1, wherein: The seed layer has a thickness thinner than that of the bulk layer.

3. The film forming method according to claim 1, wherein: The seed layer has a thickness of 0.6 nm or more.

4. The film forming method according to claim 1, wherein: The first temperature is 550° C. or lower.

5. The film forming method according to claim 1, wherein: The step of forming the seed layer includes forming the seed layer by a thermal atomic layer deposition method in which supply of the first silicon-containing gas and supply of the first nitride gas are repeatedly and alternately performed.

6. The film forming method according to claim 1, wherein: The step of forming the bulk layer includes forming the bulk layer by repeatedly and alternately performing a plasma atomic layer deposition method in which the supply of the second silicon-containing gas and exposure to plasma generated from the second nitriding gas are performed.

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

8. The film forming method according to claim 1, wherein: The first silicon-containing gas is hexachlorodisilane gas, The second silicon-containing gas is dichlorosilane gas.

9. The film forming method according to any one of claims 1 to 8, wherein: The metal film is a ruthenium film.

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 film forming apparatus comprising: a processing container that receives the substrate; a gas supply unit for supplying gas into the processing container; a heating unit configured to heat the substrate contained in the processing container; and Control Department, in, The control unit is configured to perform the following steps: 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; as well as A second silicon-containing gas and a second nitriding gas are supplied to the substrate while the substrate is maintained at a second temperature higher than the first temperature, so as to form a bulk layer including silicon atoms and nitrogen atoms on the seed layer.

Images