Substrate processing method and substrate processing apparatus

Abstract

The present invention provides a substrate processing method which includes: a step for preparing a substrate that has a conductive layer or a semiconductor layer in a processing chamber; a step for supplying a first gas that contains hydrogen and nitrogen into the processing chamber, and exposing the substrate to plasma which is generated from the first gas so as to reduce the surface of the conductive layer or the semiconductor layer; and a step for supplying a second gas that contains hydrogenated silicon or alkylated aluminum, and exposing the reduced conductive layer or the reduced semiconductor layer to the second gas so as to have silicon or aluminum adsorbed on the conductive layer or the semiconductor layer, thereby forming a stabilized layer.

Description

Substrate processing method and substrate processing apparatus

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus.

[0002] Patent Document 1 describes a method of forming an insulating film on a conductive layer formed on a semiconductor substrate, dry-etching the insulating film using a first gas containing a halogen gas to expose the surface of the conductive layer, performing a first plasma treatment on the exposed conductive layer using a second gas that can be reduced, and performing a second plasma treatment on the exposed conductive layer using a third gas that contains C and O elements but does not contain a halogen element. ２ , N ２ , N.H. ４ including, for example, N ２ / H ２ It is described that the plasma treatment is carried out using

[0003] JP 2011-243680 A

[0004] The present disclosure provides a substrate processing method and a substrate processing apparatus that can suppress corrosion of the surface of a conductive layer or a semiconductor layer.

[0005] According to one aspect of the present disclosure, there is provided a substrate processing method including the steps of: preparing a substrate having a conductive layer or a semiconductor layer in a processing chamber; supplying a first gas containing hydrogen and nitrogen into the processing chamber and exposing the substrate to plasma generated from the first gas, thereby reducing a surface of the conductive layer or the semiconductor layer; and supplying a second gas containing hydrogenated silicon or alkylated aluminum, and exposing the reduced conductive layer or the semiconductor layer to the second gas, thereby adsorbing silicon or aluminum onto the conductive layer or the semiconductor layer, thereby forming a stabilization layer.

[0006] According to one aspect, corrosion of the surface of the conductive layer or semiconductor layer can be suppressed.

[0007] 1. A flowchart showing a conventional example of a substrate processing method. A diagram showing an example of a plasma processing apparatus. A flowchart showing an example of a substrate processing method according to an embodiment. An example of a schematic cross-sectional view of a wafer at each process. An example of a schematic cross-sectional view of a wafer at each process. An example of a schematic cross-sectional view of a wafer at each process. An example of a schematic cross-sectional view of a wafer at each process. An example of a schematic cross-sectional view of a wafer at each process. A graph showing an example of the relationship between the pressure in a processing chamber and ion energy. A graph showing an example of the relationship between the ratio of H atoms to the sum of H and N atoms and the contact angle. A graph showing an example of the relationship between the ratio of H atoms to the sum of H and N atoms and the surface roughness. An example of a schematic cross-sectional view of a wafer with and without stabilization processing. A graph showing an example of an XPS analysis result. A graph showing an example of an XPS analysis result. A graph showing an example of an XPS analysis result.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0009] [Conventional example of substrate processing method] Etching of metal film (conductive layer) and SiF ４ When selectively depositing a film using a gas or other chemical, the use of an etchant or precursor containing a halogen compound can result in halogenation or oxidation of the metal film. For example, halogenation of a metal film results in the adsorption of the halogen compound onto the surface of the metal film. When a halogenated or oxidized metal film is exposed to the atmosphere, the surface of the metal film reacts with water, causing corrosion, which can adversely affect the formation of metal patterns or even destroy devices. Therefore, substrate processing methods to suppress corrosion are important.

[0010] An example of a substrate processing method that has been conventionally used as a general corrosion prevention measure will be described with reference to Fig. 1. In Fig. 1, a film formation process is performed in step S1. For example, a SiF ４ When forming an insulating film using a gas, SiF ４ The fluorine contained in the gas causes halogenation of the metal film.

[0011] In step S2, H２ After generating plasma from the gas and exposing the halogenated metal film to the plasma for treatment, in step S3, water is supplied to the wafer surface and the wafer surface is washed with water, which removes excess halogen.

[0012] However, this method requires management of the time the wafer is exposed to the atmosphere for water cleaning (referred to as Q-Time), which makes the process complicated. Therefore, it is important to develop a process that can suppress corrosion without exposing the wafer to the atmosphere instead of water cleaning, or a process that can extend the Q-Time.

[0013] Therefore, in the substrate processing method according to the present embodiment, corrosion of the surface of the conductive layer or semiconductor layer is suppressed by performing a surface treatment on the conductive layer or semiconductor layer. Hereinafter, an example of the configuration of a substrate processing apparatus according to an embodiment that can perform the substrate processing method according to an embodiment will be described with reference to FIG. 2. Then, an example of the substrate processing method according to an embodiment will be described with reference to FIG. 3.

[0014] [Substrate Processing Apparatus] Fig. 2 is a diagram showing an example of a plasma processing apparatus. Fig. 2 shows a schematic cross-sectional structure of a plasma processing apparatus 10 that can be used in various embodiments of a substrate processing method for a substrate, an example of which is a wafer W. As shown in Fig. 2, the plasma processing apparatus 10 is an inductively coupled plasma processing apparatus. The plasma processing apparatus 10 is an example of a substrate processing apparatus. The substrate processing apparatus is not limited to an inductively coupled plasma processing apparatus, and plasma processing apparatuses such as capacitively coupled plasma processing apparatuses and microwave plasma processing apparatuses can also be used. The insulating film formed on the wafer W is a film containing at least silicon (Si) and oxygen (O), and may be, for example, SiO ｘ It may be a film or a SiOF film.

[0015] The plasma processing apparatus 10 includes a processing vessel 1. The processing vessel 1 is airtightly sealed. The processing vessel 1 includes a conductive material, and for example, the inner wall surface of the processing vessel 1 may include a material such as anodized aluminum. The processing vessel 1 is assembled so as to be disassembled, and is grounded by a grounding wire 1a. The processing vessel 1 is partitioned into an antenna chamber 3 and a processing chamber 4 above and below by a dielectric wall 2. The dielectric wall 2 forms the ceiling wall of the processing chamber 4. The dielectric wall 2 is made of, for example, Al ２ O ３ It is made of ceramics such as quartz, etc.

[0016] A shower housing 11 for supplying processing gas is fitted into the lower portion of the dielectric wall 2. The shower housing 11 is provided in a cross shape and supports the dielectric wall 2 from below. The shower housing 11 supporting the dielectric wall 2 is suspended from the ceiling of the processing vessel 1 by a plurality of suspenders (not shown).

[0017] The shower housing 11 may include a conductive material such as metal. The inner surface of the shower housing 11 may include, for example, anodized aluminum to prevent contamination. The shower housing 11 is formed with a gas flow path 12 extending along the dielectric wall 2, and a plurality of gas supply holes 12a extending toward the mounting table 22 are connected to the gas flow path 12. A gas supply pipe 20a is provided in the center of the upper surface of the dielectric wall 2 so as to communicate with the gas flow path 12. The gas supply pipe 20a extends from the dielectric wall 2 to the outside of the processing chamber 1 and is connected to a processing gas supply system 20 including a processing gas supply source, a valve system, etc. The processing gas supply source is a gas containing SiF ４ Gas supply sources 51a, O ２ Gas supply sources 52a, H ２ Gas supply source 53a, N ２ Gas supply source 54a, SiH ４ The chamber 50 includes a gas supply source 55a and an Ar gas supply source 56a.

[0018] SiF ４ The gas supply source 51a supplies SiF via a gas supply line 51b. ４The gas is supplied into the processing chamber 4. A flow rate controller 51c and a valve 51d are provided in the gas supply line 51b from the upstream side. The downstream side of the valve 51d of the gas supply line 51b is connected to the gas supply pipe 20a via a gas supply line 57. SiF ４ SiF supplied from the gas supply source 51a ４ The supply and stop of gas is controlled by opening and closing the valve 51d.

[0019] O ２ The gas supply source 52a supplies O via a gas supply line 52b. ２ The gas is supplied into the processing chamber 4. A flow rate controller 52c and a valve 52d are provided in the gas supply line 52b from the upstream side. The downstream side of the valve 52d of the gas supply line 52b is connected to the gas supply pipe 20a via a gas supply line 57. ２ O supplied from the gas supply source 52a ２ The supply and stop of gas is controlled by opening and closing the valve 52d.

[0020] H ２ The gas supply source 53a supplies H ２ The gas is supplied into the processing chamber 4. A flow rate controller 53c and a valve 53d are provided in the gas supply line 53b from the upstream side. The downstream side of the valve 53d of the gas supply line 53b is connected to the gas supply pipe 20a via a gas supply line 57. ２ H supplied from the gas supply source 53a ２ The supply and stop of gas is controlled by opening and closing the valve 53d.

[0021] N ２ The gas supply source 54a supplies N ２ Gas is supplied into the processing chamber 4. A flow rate controller 54c and a valve 54d are provided on the gas supply line 54b from the upstream side. The downstream side of the valve 54d on the gas supply line 54b is connected to the gas supply pipe 20a via a gas supply line 57. ２ N supplied from the gas supply source 54a ２ The supply and stop of gas is controlled by opening and closing the valve 54d.

[0022] SiH４ The gas supply source 55a supplies SiH ４ The gas is supplied into the processing chamber 4. A flow rate controller 55c and a valve 55d are provided on the gas supply line 55b from the upstream side. The downstream side of the valve 55d on the gas supply line 55b is connected to the gas supply pipe 20a via a gas supply line 57. SiH ４ SiH supplied from the gas supply source 55a ４ The supply and stop of gas is controlled by opening and closing the valve 55d.

[0023] The Ar gas supply source 56a supplies Ar gas into the processing chamber 4 via a gas supply line 56b. A flow rate controller 56c and a valve 56d are provided on the gas supply line 56b from the upstream side. The downstream side of the valve 56d on the gas supply line 56b is connected to the gas supply pipe 20a via a gas supply line 57. The supply of Ar gas from the Ar gas supply source 56a is started and stopped by opening and closing the valve 56d.

[0024] In plasma processing, the processing gas supplied from the processing gas supply system 20 is supplied into the shower housing 11 via the gas supply pipe 20a and is discharged into the processing chamber 4 from the gas supply holes 12a on the underside of the shower housing 11 (the surface facing the processing chamber 4).

[0025] A support shelf 5 protruding inward is provided between a side wall 3 a of the antenna chamber 3 and a side wall 4 a of the processing chamber 4 in the processing vessel 1 , and the dielectric wall 2 is placed on the support shelf 5 .

[0026] Within the antenna chamber 3, a high-frequency antenna 13 is disposed on top of the dielectric wall 2 so as to face the dielectric wall 2. The high-frequency antenna 13 is separated from the dielectric wall 2 by a spacer 13a made of an insulating material, for example, within a range of 50 mm or less. Four power supply members 16 extending perpendicular to the top surface of the dielectric wall 2 (vertical direction) are provided near the center of the antenna chamber 3, and high-frequency power sources 15 are connected to the four power supply members 16 via matching boxes 14. The power supply members 16 are disposed around the gas supply pipe 20a.

[0027] During plasma processing, high-frequency power supply 15 supplies plasma-generating high-frequency power (RF) of, for example, about 13.56 MHz for forming an induction electric field into processing chamber 4 via high-frequency antenna 13. By supplying high-frequency power supply 15 for plasma generation into processing chamber 4 in this manner, an induction electric field is formed within processing chamber 4, and this induction electric field generates plasma of the processing gas supplied from shower housing 11 into processing chamber 4. Note that shower housing 11 is arranged in a cross shape, and the supply of high-frequency power from high-frequency antenna 13 into processing chamber 4 is not impeded even if shower housing 11 is made of metal.

[0028] A mounting table 22 is provided at the bottom of the processing chamber 4 (on the opposite side of the dielectric wall 2). The mounting table 22 faces the high-frequency antenna 13 across the dielectric wall 2. A wafer W is placed on the mounting table 22. The mounting table 22 may include a conductive material. The surface of the mounting table 22 may include, for example, anodized aluminum or aluminum sprayed with alumina. The wafer W placed on the mounting table 22 is attracted and held to the mounting table 22 by an electrostatic chuck (not shown).

[0029] The mounting table 22 is housed in an insulator frame 24 and supported by support columns 25. The support columns 25 have a hollow structure. Bellows 26 are disposed between the insulator frame 24 housing the mounting table 22 and the bottom of the processing vessel 1 (the side of the processing vessel 1 where the support columns 25 are provided) to airtightly surround the support columns 25. A sidewall 4a of the processing chamber 4 is provided with a load / unload port 27a for loading / unloading the wafer W and a gate valve 27 for opening / closing the load / unload port 27a.

[0030] The mounting table 22 is connected to a high-frequency power supply 29 via a power feed rod 25a provided in a support 25 and a matching box 28. During plasma processing, the high-frequency power supply 29 applies a high-frequency bias power, for example, a high-frequency bias power having a frequency of about 400 kHz to 6 MHz, to the mounting table 22. This high-frequency bias power can effectively attract ions in the plasma generated in the processing chamber 4 to the wafer W.

[0031] A temperature control mechanism including a heating means such as a ceramic heater 21 and a coolant flow path, and a temperature sensor (none of which are shown) are provided within the mounting table 22 for the purpose of controlling the temperature of the wafer W. Piping and wiring for the temperature control mechanism, the temperature sensor, and components are all routed through the inside of the support 25 to the outside of the processing chamber 1.

[0032] An exhaust device 30 including a vacuum pump and the like is connected to the bottom of the processing chamber 4 (the side of the processing chamber 4 where the support 25 is provided) via an exhaust pipe 31. The processing chamber 4 is evacuated by the exhaust device 30, and a predetermined vacuum atmosphere (e.g., a pressure of about 1.33 [Pa]) is set and maintained inside the processing chamber 4 during plasma processing.

[0033] The high-frequency antenna 13 has four power feeders (e.g., power feeder 41, power feeder 43, etc.). The four power feeders are connected to a power feed member 16. The four power feeders are spaced apart, for example, at approximately 90 degrees around the center of the high-frequency antenna 13. Two antenna wires extend outward from each of the four power feeders, and each antenna wire is grounded via a capacitor 18.

[0034] The plasma processing apparatus 10 includes a control unit Cnt. The control unit Cnt is a computer including a processor, a storage unit, an input device, a display device, etc., and controls each unit of the plasma processing apparatus 10. When the control unit Cnt is provided outside the plasma processing apparatus 10, the control unit Cnt can control the plasma processing apparatus 10 via a communication means such as a wired or wireless communication means.

[0035] The control unit Cnt operates in accordance with a program based on the input recipe and sends control signals. The control signals from the control unit Cnt can control the selection and flow rate of gas supplied from the process gas supply system 20, the exhaust of the exhaust unit 30, the power supply from the high-frequency power supplies 15 and 29, and the temperature of the mounting table 22. Each process for processing a substrate disclosed in this specification (steps S1 to S2 shown in FIG. 1) can be performed by operating each component of the plasma processing apparatus 10 under the control of the control unit Cnt.

[0036] [Substrate Processing Method] An example of a substrate processing method ST according to one embodiment will be described with reference to Figures 3 and 4A to 4E. Figure 3 is a flowchart illustrating an example of a substrate processing method ST according to one embodiment. Figures 4A to 4E are exemplary cross-sectional views of a wafer W at each step. Here, an example will be described in which a SiOF film is formed as an insulating layer on a wafer W using a plasma processing apparatus 10, and then a treatment process (reduction process, stabilization process) described below is performed.

[0037] In step S11, the controller Cnt prepares a wafer W in the processing vessel 1 and performs a film formation process. Specifically, the gate valve 27 is opened while the mounting table 22 is lowered to the transfer position. The wafer W is then loaded into the processing vessel 1 via the loading / unloading port 27a using a transfer arm (not shown) and placed on the mounting table 22, which has been heated to a predetermined temperature (e.g., room temperature to 350°C) by the ceramic heater 21. The mounting table 22 is then raised to the processing position, and the exhaust device 30 depressurizes the processing vessel 1 to a predetermined vacuum level. After depressurization, the controller Cnt opens the valve 56d and controls the flow rate controller 56c to supply Ar gas from the Ar gas supply source 56a. This stabilizes the pressure inside the processing vessel 1 (processing chamber 4) at a predetermined level.

[0038] As shown in FIG. 4A , the wafer W prepared in the processing chamber 1 has an insulating layer 101 and a conductive layer 102. The surface of the wafer W is formed by performing damascene followed by CMP (Chemical-Mechanical-Polishing or Planarization). The conductive layer 102 is formed through the damascene process. The conductive layer 102 is embedded in the insulating layer 101 on the surface of the wafer W, and the surfaces of the conductive layer 102 and the insulating layer 101 are exposed on the front side of the wafer W. The material of the conductive layer 102 may be, for example, any of copper (Cu), aluminum (Al), ruthenium (Ru), titanium (Ti), molybdenum (Mo), cobalt (Co), tungsten (W), and tantalum (Ta).

[0039] 4A , the wafer W prepared in the processing chamber 1 may have a semiconductor layer instead of the conductive layer 102. In this case, the semiconductor layer is embedded in the insulating layer 101 on the front surface of the wafer W, and the surfaces of the semiconductor layer and the insulating layer 101 are exposed on the front surface side of the wafer W. The material of the semiconductor layer may be, for example, silicon (Si) or IGZO, an oxide semiconductor.

[0040] The material of the insulating layer 101 can be a low-k film or a metal oxide insulating film. The material of the insulating layer 101 can be SiO ｘ , Si ｘ N ｙ , SiC ｘ , SiOC, SiOCH, Al ｘ O ｙ The insulating film may be an insulating film such as the above.

[0041] In step S11, the control unit Cnt performs a film formation process on the wafer W. As an example of the film formation process, as shown in FIG. 4B , a SiOF film 103 is selectively formed on the surface of the insulating layer 101. Therefore, the SiOF film 103 is not formed on the surface of the conductive layer 102.

[0042] In the film formation process of the SiOF film 103, the control unit Cnt maintains the supply of Ar gas while opening the valve 52d and controlling the flow rate controller 52c to supply O ２ Gas supply source 52a to O ２ Supply gas.

[0043] Next, the control unit Cnt supplies plasma generating radio frequency power (RF) to the processing chamber 4 via the radio frequency antenna 13 by the radio frequency power supply 15, ２ A plasma is generated from the gas.

[0044] Next, the control unit Cnt opens the valve 51d and controls the flow rate controller 51c to ４ The gas supply source 51a supplies SiF ４ The control unit Cnt controls the high frequency power source 15 to supply high frequency power for plasma generation to the processing chamber 4 via the high frequency antenna 13, and controls the SiF ４ Plasma is generated from the gas. ４ The generation of gas plasma is ２Simultaneously with the generation of gas plasma, ２ It is sufficient if it is after the gas plasma is generated.

[0045] O ２ Gas and SiF ４ The plasma of the gas forms a SiOF film on the wafer W. After a predetermined time has elapsed, the control unit Cnt closes the valves 56d, 52d, and 51d, and the Ar gas and O ２ Gas, SiF ４ The gas supply is stopped and the gas is removed from the processing chamber 4 .

[0046] If a reduction process, which will be described later, is not performed in this state, the surface of the conductive layer 102 in particular will corrode, causing corrosion. As a result, as shown in Fig. 4C, a halide 104 is formed on the conductive layer 102. For this reason, the control unit Cnt performs a reduction process to suppress corrosion after performing the film formation process in step S11.

[0047] In order to increase the reduction efficiency in step S13, in step S12, the control unit Cnt opens the valve 53d and controls the flow rate controller 53c to ２ Gas supply sources 53a to H ２ The gas is supplied to control the pressure in the processing chamber 1 within a range of 20 Pa to 100 Pa. ２ While maintaining the supply of gas, the inside of the processing chamber 4 is purged. ２ H from the gas supply source 53a ２ While controlling the flow rate of the gas, the exhaust device 30 is controlled to control the pressure inside the processing chamber 4 to 20 Pa or more and 100 Pa or less.

[0048] 5 is a graph showing an example of the relationship between the pressure in the processing chamber 4 and the ion energy. The horizontal axis, "Pressure," represents the pressure in the processing chamber 4, and the vertical axis, "Ion Energy," represents the ion energy. In the graph, the ion energy decreases as the pressure in the processing chamber 4 increases. In the range of 20 Pa to 100 Pa, the ion energy is small, so that damage by ions is small and the roughness of the wafer W surface is improved.

[0049] H２ After the gas flow rate and the pressure in the processing chamber 4 are adjusted, the process of the control unit Cnt proceeds to step S13. ２ While maintaining the gas supply, a first gas containing hydrogen and nitrogen is supplied into the processing chamber 4, and the wafer W is exposed to plasma generated from the first gas. ２ Gas, NH ３ Here, as an example, H ２ gas and N as the first gas ２ Supply gas.

[0050] The control unit Cnt opens the valve 54d while the valve 53d is open, and controls the flow rate controllers 53c and 54c to ２ Gas supply source 53a and N ２ H is introduced into the processing chamber 4 from the gas supply source 54a. ２ Gas and N ２ The control unit Cnt supplies plasma generating radio frequency power (RF) to the processing chamber 4 via the radio frequency antenna 13 from the radio frequency power supply 15, and generates H ２ Gas and N ２ A plasma is generated from the gas. The wafer W is exposed to the generated plasma to reduce the surface of the conductive layer 102. After a predetermined time has elapsed, the control unit Cnt closes the valves 53d and 54d and ２ Gas and N ２ The gas supply is stopped and the gas is evacuated from the processing chamber 4 .

[0051] In the reduction process, the first gas is H ２ Gas containing N ２ If no gas is contained, it is difficult to reduce the surface of the conductive layer 102, making it difficult to remove the halogen compounds. In contrast, if a bias power is applied from the high-frequency power supply 29 to the mounting table 22 to provide ion energy and remove the halogen compounds, the surface roughness of the conductive layer 102 will worsen.

[0052] The first gas is H 2 O 4 to facilitate reduction of the surface of the conductive layer 102, promote removal of halogen compounds, and improve the surface roughness of the conductive layer 102. ２ Trace amounts of N in the gas ２The surface of the conductive layer 102 is treated with a mixed gas containing H ２ and N ２ 4D, the halide 104 is removed from the surface of the conductive layer 102. However, the surface of the conductive layer 102 becomes unstable (active), and an altered layer 105 is formed on the surface of the conductive layer 102, and some halide 104 remains.

[0053] Therefore, in step S14, the control unit Cnt exposes the conductive layer 102 to the second gas to adsorb silicon or aluminum onto the conductive layer 102, thereby forming a stabilization layer.

[0054] In this stabilization process, the valve 56d is opened, and the flow rate controller 56c is controlled to supply Ar gas from the Ar gas supply source 56a into the processing chamber 4, while supplying a second gas containing hydrogenated silicon or alkylated aluminum into the processing chamber 4. The second gas is SiH ４ , Si ２ H ６ , TMA(Al(CH ３ ) ２ ), or TMAH(AlH(CH ３ ) ２ ) In this example, an example of the second gas is SiH ４ Supply gas.

[0055] The control unit Cnt opens the valve 55d and controls the flow rate controller 55c to ４ The gas supply source 55 a supplies SiH ４ Gas is supplied. SiH ４ By exposing the wafer W to the gas, silicon is adsorbed onto the surface of the conductive layer 102 and stabilized.

[0056] As a result, as shown in FIG. 4E, a stabilizing layer 106 is formed on the surface of the conductive layer 102, which can prevent or suppress deterioration of the surface of the conductive layer 102 and suppress corrosion.

[0057] In step S14, the controller Cnt may control the temperature of the mounting table 22 to a temperature equal to or higher than room temperature but equal to or lower than 350°C, which is temperature controllable by the ceramic heater 21. This allows silicon or aluminum contained in the second gas to be adsorbed onto the conductive layer 102 whose surface has been reduced, thereby forming a stabilization layer 106. However, to more reliably form the stabilization layer 106, it is preferable to control the temperature of the mounting table 22 to a temperature equal to or higher than room temperature but equal to or lower than 100°C.

[0058] In step S14, plasma is not generated from the second gas. If plasma is used, a silicon film would be formed on the conductive layer 102, and it would be impossible to adsorb the silicon or aluminum contained in the second gas onto the conductive layer 102 and form the stabilizing layer 106. Note that the stabilizing layer 106 does not have to be layer-shaped, as long as the surface of the conductive layer 102 is stable. After executing step S14, the control unit Cnt terminates the substrate processing method ST.

[0059] The reduction and stabilization treatments are preferably performed in a vacuum atmosphere, but may also be performed in a controlled atmosphere. In the controlled atmosphere, the atmospheric gas may be a gas that does not or hardly reacts with the active surface.

[0060] According to the substrate processing method ST, in the reduction process, the surface of the conductive layer 102 is exposed to plasma of the first gas to clean the surface of the conductive layer 102. Next, in the stabilization process, the surface of the conductive layer 102, which has become unstable (activated) by the reduction process, is cleaned by exposing the surface of the conductive layer 102 to plasma of the first gas. ４ The surface of the conductive layer 102 is then treated with a second gas such as TMA to stabilize the surface of the conductive layer 102. This makes it possible to suppress corrosion of the surface of the conductive layer 102 and the generation of an altered layer 105.

[0061] Furthermore, in the reduction process, the ion energy can be reduced by controlling the pressure inside the process vessel 1 to a range of 20 Pa to 100 Pa. This reduces damage caused by ions and improves the roughness of the surface of the conductive layer 102. This makes it possible to achieve both suppression of corrosion on the surface of the conductive layer 102 and good roughness.

[0062] [Experimental Results] In the reduction process, the ratio of hydrogen atoms to the sum of hydrogen atoms and nitrogen atoms contained in the first gas (hereinafter referred to as H / H+N) may be 0.75 to less than 1 (0.99). The ratio of hydrogen atoms to the sum of hydrogen atoms and nitrogen atoms in the first gas (H / H+N) may be 0.95 to less than 1 (0.99). Experimental results regarding the value of H / H+N will be described below with reference to FIGS. 6 and 7.

[0063] Fig. 6 is a graph showing an example of the relationship between the ratio of H atoms to the sum of H and N atoms (H / H+N) and the contact angle θe. The horizontal axis of Fig. 6 represents H / H+N, and the vertical axis represents the contact angle θe of water. Fig. 7 is a graph showing an example of the relationship between the ratio of H atoms to the sum of H and N atoms (H / H+N) and the surface roughness. The horizontal axis of Fig. 7 represents H / H+N, and the vertical axis represents roughness (RMS). In the experiments of Figs. 6 and 7, a Cu film formed by plating was used for the conductive layer 102.

[0064] 6 and 7, the black circles (●) indicate that the first gas is H ２ Gas and N ２ When mixed with gas, H ２ Gas and N ２ H for the sum of gases ２ Gas ratio (H ２ / H ２ +N ２ 6 and 7 show the relationship between the contact angle θe and the roughness by converting the contact angle θe to H / H+N. ２ Gas and NH ３ When mixed with gas, H ２ Gas and NH ３ H for the sum of gases ２ Gas ratio (H ２ / H ２ +NH ３ ) is converted to H / H+N and the relationship between the contact angle θe and the roughness is shown. ２ Gas and NH ３ When mixed with gas, NH ３ N for ２ Gas ratio (N ２ / NH ３ ) with NH３ The relationship between H and N in the graph is shown as H / H+N, assuming H:N=3:1, and the relationship is shown as the contact angle θe and the roughness.

[0065] 6 shows the results of exposing the surface of the conductive layer 102, a Cu film formed by copper plating, to plasma generated from each of the three types of mixed gases. The graph shows the hydrophilic behavior of the surface of the conductive layer 102, with the water contact angle θe on the vertical axis.

[0066] According to this, when the surface of the conductive layer 102 is cleaned by the reduction treatment and becomes hydrophilic, the contact angle θe increases. If the contact angle θe is between 40 degrees and 45 degrees, it can be determined that the surface of the conductive layer 102 is clean. Furthermore, if the contact angle θe is approximately constant at 40 degrees to 45 degrees or more, it can be determined that the surface of the conductive layer 102 remains clean and unchanged.

[0067] From the graph, it can be seen that the first gas is H ２ Gas and N ２ When the first gas is a mixed gas with H ２ Gas and NH ３ When the first gas was a mixed gas with H gas (△), the contact angle θe was approximately 45 degrees or more when H / H+N was in the range of 0.75 to less than 1, and the surface of the conductive layer 102 was highly hydrophilic. In other words, the surface of the conductive layer 102 was cleaned. In particular, when the first gas was H ２ Gas and N ２ When the first gas was a mixed gas with N gas (●), the contact angle θe was higher than 45 degrees when H / H+N was in the range of 0.95 to less than 1, and the hydrophilicity of the surface of the conductive layer 102 was further increased. In other words, the surface of the conductive layer 102 was further cleaned. ２ Gas and NH ３ When the gas mixture was a gas (◯), the contact angle θe was approximately constant at 40 to 45 degrees or more when H / H+N was in the range of about 0.5 to about 0.7, and the surface of the conductive layer 102 was cleaned.

[0068] 7, when the roughness is on the order of 1 nm or less, the surface roughness of the conductive layer 102 is in a good state. In other words, the surface of the conductive layer 102 is flat with no irregularities.

[0069] From the graph, it can be seen that the first gas is H ２ Gas and N ２ When the first gas is a mixed gas with H ２ Gas and NH ３ When the first gas was a mixed gas with N gas (Δ), the roughness was approximately in the 1 nm range, and the surface of the conductive layer 102 was flat and in a good condition. ２ Gas and NH ３ When the mixed gas of (◯) was used, the roughness was about twice as large as the 1 nm level, and the surface of the conductive layer 102 was not flat, resulting in a poor condition.

[0070] From the above, it can be seen that the first gas is H ２ Gas and N ２ Gas mixture with N ２ Gas and NH ３ When the first gas used in the reduction treatment was a mixed gas of H 2 O 3 and H 2 O 3 , both the cleaning of the surface of the conductive layer 102 and the roughness of the surface of the conductive layer 102 were favorable. ２ Gas and N ２ Mixture of N ２ Gas and NH ３ It has been found that either a gas mixture with a gas can be used.

[0071] 8 shows an example of a schematic cross-sectional view of a wafer W with and without stabilization treatment. In the experiment shown in FIG. 8, a Cu film formed by plating was used for the conductive layer 102. In the stabilization step, the atmosphere was controlled to a vacuum atmosphere, and the second gas was H ２ Gas and N ２ A mixed gas containing a Cu gas was used. FIG. 8( a) shows a TEM image of the conductive layer 102 after the reduction treatment under these conditions and before the stabilization treatment. In FIG. 8( a), an unstable altered layer 105 was formed on the surface of the conductive layer 102 of the Cu film. At this time, the wafer W was not exposed to the atmosphere. Thereafter, the wafer W was exposed to the atmosphere for two hours. FIG. 8( b) shows a TEM image of the conductive layer 102 after the wafer W was exposed to the atmosphere for two hours.

[0072] 8B, an unstable altered layer 105 has thickened on the surface of the conductive layer 102. It is believed that exposure of the wafer W having the halogenated conductive layer 102 to the atmosphere caused the surface of the conductive layer 102 to react with water, resulting in corrosion, which caused the altered layer 105 to thicken.

[0073] 8A and 8B, the stabilization treatment was not performed after the reduction treatment. In contrast, FIG. 8C shows a TEM image of the conductive layer 102 after the reduction treatment and the stabilization treatment without exposure to the atmosphere.

[0074] In Fig. 8(c), the altered layer 105 on the surface of the conductive layer 102 has been significantly improved. Fig. 8(d) shows a TEM image of the conductive layer 102 after being exposed to the atmosphere for two hours from the state shown in Fig. 8(c). In Fig. 8(d), the altered layer 105 on the surface of the conductive layer 102 has not changed from the significantly improved state shown in Fig. 8(c), and corrosion has been suppressed by the stabilizing layer on the surface of the conductive layer 102.

[0075] 9 and 10A to 10B are graphs showing an example of the results of XPS analysis of a Cu film formed on a substrate. Here, XPS analysis was performed on a wafer on which a Cu film was formed by plating in an experiment, simulating the conductive layer 102.

[0076] 9(a) to 9(d), the "Initial" indicated by the dashed line shows the XPS analysis results of the Cu film surface before the reduction treatment is performed on the wafer on which the Cu film is formed. The "H2 Vessel" indicated by the dashed line shows the H ２ The figure shows the results of XPS analysis of the Cu film surface after the Cu film was reduced using plasma. The "H2 / N2 Vessel" shown by the solid line indicates the H2 / N2 Vessel for the wafer on which the Cu film was formed. ２ Gas N ２ This figure shows the results of XPS analysis of the Cu film surface after reduction treatment using plasma with trace amounts of added gas. In this experiment, the H / H+N ratio was set to 0.95. The horizontal axis represents bond energy, and the vertical axis represents the number of detections per unit time.

[0077] 9(a) shows the XPS analysis results of C 1s, FIG. 9(b) shows the XPS analysis results of O 1s, FIG. 9(c) shows the XPS analysis results of Cu 2p, and FIG. 9(d) shows the XPS analysis results of Cu LMM.

[0078] From the results of Figures 9(a) and 9(b), when comparing "Initial" and "H2 Vessel", H ２ By subjecting the Cu film to reduction treatment using plasma, the amount of oxygen captured in the surface of the Cu film was reduced, and the oxidation state of the surface of the Cu film was improved.

[0079] Also, H ２ Gas N ２ By reducing the Cu film using plasma with a small amount of gas added, oxygen was efficiently removed from the surface of the Cu film at low ion energy, as shown in "H2 / N2 Vessel."

[0080] On the other hand, from the results of Fig. 9(c) and (d), it is clear that Cu ＋ This is consistent with the formation of the altered layer shown in Figures 8(a) and 8(b).

[0081] 10A and 10B are graphs showing examples of XPS analysis results with and without stabilization treatment. FIG. 10A is the same graph as FIG. 9(d), and shows that an altered layer was formed on the Cu surface after reduction treatment due to reoxidation of Cu. In contrast, FIG. 10B shows that SiH ４ The figure shows the surface of the Cu film after gas supply and stabilization treatment.

[0082] The "Initial" indicated by the dashed line in FIG. 10B shows the XPS analysis results of the Cu film surface before the stabilization treatment is performed on the wafer on which the Cu film is formed. The "H + SiH Flow atm" indicated by the dashed line indicates the H + SiH Flow atm for the wafer on which the Cu film is formed. ２ After reducing the Cu film using plasma, SiH ４ The figure shows the results of XPS analysis of the Cu film surface after stabilization treatment by exposing the Cu film surface to gas. The dashed line "H / N + SiH Flow atm" indicates the flow rate of H for the wafer on which the Cu film is formed. ２ Gas N２ After reducing the Cu film using plasma with a small amount of added gas, SiH ４ The results of XPS analysis of the Cu film surface after stabilization treatment by exposing the Cu film surface to gas are shown. 4 Flow atm" is the H ２ NH in gas ３ After reducing the Cu film using plasma with a small amount of added gas, SiH ４ The figure shows the results of XPS analysis of the Cu film surface after stabilization treatment by exposing the Cu film surface to gas. In this experiment, H / H+N=0.95. The horizontal axis shows the bond energy, and the vertical axis shows the number of detections per unit time.

[0083] According to this, after the stabilization treatment of the wafer on which the Cu film was formed, the Cu surface was more stabilized than before the stabilization treatment, and the altered layer was significantly improved, which is consistent with the significant improvement of the altered layer and stabilization of the Cu surface shown in Figure 8(c).

[0084] An example of the process conditions for the above experiment is as follows: (Reduction treatment) H ２ Plasma H ２ Gas: 500 sccm Pressure: 20 Pa Temperature: 100°C RF power: 2000 W (upper electrode) / 50 W (lower electrode) H ２ / N ２ Plasma H ２ Gas: 475 sccm N ２ Gas: 25 sccm Pressure: 20 Pa Temperature: 100°C RF power: 1000 W (upper electrode)

[0085] (Stabilization treatment) SiH ４ Flow SiH ４ Gas: 36 sccm Pressure: 15 Pa Temperature: 100°C

[0086] [Others] The substrate processing method ST according to this embodiment can suppress corrosion of the surface of a conductive layer or semiconductor layer formed using a halogen-containing gas precursor. However, this is not limited to this, and the method can be suitably applied to a conductive layer of an underlying layer that has undergone a process using a halogen-containing gas, such as etching with a halogen-containing gas. For example, the process shown in step S11 (film formation process) in FIG. 3 may be a process other than a film formation process, such as etching using a halogen-containing gas.

[0087] 3 is preferably performed in a vacuum atmosphere, or may be performed in a controlled atmosphere. Alternatively, the processes in steps S11 to S14 may be performed in the same substrate processing apparatus. Alternatively, the substrate processing apparatus performing the process in step S11, the substrate processing apparatus performing the processes in steps S12 and S13, and the substrate processing apparatus performing the process in step S14 may be connected by a vacuum transfer chamber or a transfer chamber with a controlled atmosphere. This prevents the wafer W from being exposed to the atmosphere after the reduction process in step S13 and before the stabilization process in step S14, thereby preventing the formation of an unstable altered layer on the surface of the conductive layer 102.

[0088] The substrate processing apparatus is not limited to a single-wafer processing apparatus such as CVD (Chemical Vapor Deposition) or ALD (Atomic Layer Deposition), which processes wafers one by one. For example, the substrate processing apparatus may be a batch processing apparatus in which multiple wafers are held in a wafer boat and loaded into a processing vessel, and multiple wafers are processed at once. Furthermore, for example, the substrate processing apparatus may be a semi-batch processing apparatus in which multiple wafers placed on a rotary table in a processing vessel are revolved by the rotary table, and the wafers are processed by passing them sequentially through an area where one gas is supplied and an area where another gas is supplied. Furthermore, for example, the film formation apparatus may be a multi-wafer film formation apparatus equipped with multiple mounting tables in a single processing vessel.

[0089] As described above, according to the substrate processing method and substrate processing apparatus of this embodiment, corrosion of the surface of the conductive layer or semiconductor layer can be suppressed.

[0090] The substrate processing method and substrate processing apparatus according to the presently disclosed embodiments should be considered to be illustrative in all respects and not restrictive. The embodiments can be modified and improved in various ways without departing from the spirit and scope of the appended claims. The features described in the above embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent.

[0091] This international application claims priority based on Japanese Patent Application No. 2023-216138, filed on December 21, 2023, the entire contents of which are incorporated herein by reference.

[0092] 1...processing vessel, 1a...ground wire, 2...dielectric wall, 3...antenna chamber, 3a...side wall, 4...processing chamber, 4a...side wall, 5...support shelf, 10...plasma processing apparatus, 11...shower housing, 12...gas flow path, 12a...gas supply hole, 13...high frequency antenna, 13a...spacer, 14...matching box, 15...high frequency power source, 16...power supply member, 18...capacitor, 20...processing gas supply system, 20a...gas supply pipe, 21...ceramic heater, 22...mounting table, 24...insulator frame, 25...support, 25a...power supply rod, 26...bellows, 27...gate valve, 27a...loading / unloading port, 28...matching box, 29...high frequency power source, 30...exhaust device, 31...exhaust pipe, 41...power supply unit, 43...power supply unit, 51a...SiF ４ Gas supply source, 52a...O ２ Gas supply source, 53a...H ２ Gas supply sources, 54a...N ２ Gas supply source, 55a...SiH ４ Gas supply source, 56a...Ar gas supply source, 101...insulating layer, 102...conductive layer, 103...SiOF film, Cnt...controller, W...wafer.

Claims

1. A substrate processing method comprising the steps of: preparing a substrate having a conductive layer or a semiconductor layer in a processing vessel; supplying a first gas containing hydrogen and nitrogen into the processing vessel, and exposing the substrate to plasma generated from the first gas, thereby reducing a surface of the conductive layer or the semiconductor layer; and supplying a second gas containing hydrogenated silicon or alkylated aluminum, and exposing the reduced conductive layer or the semiconductor layer to the second gas, thereby adsorbing silicon or aluminum onto the conductive layer or the semiconductor layer to form a stabilizing layer.

2. The substrate processing method according to claim 1, wherein the ratio of hydrogen atoms to the sum of hydrogen atoms and nitrogen atoms contained in said first gas is 0.75 to less than 1.

3. The first gas is H ２ Gas and N ２ Gas mixture, H ２ Gas and NH ３ 3. The method of claim 2, wherein the gas is a mixture of gases.

4. The substrate processing method according to claim 2, wherein a ratio of hydrogen atoms to the sum of hydrogen atoms and nitrogen atoms contained in said first gas is 0.95 to less than 1.

5. The first gas is H ２ Gas and N ２ The method of claim 4 , wherein the gas is a mixture of gases.

6. The second gas is SiH ４ , Si ２ H ６ , TMA(Al(CH ３ ) ２ ), or TMAH(AlH(CH ３ ) ２ The substrate processing method according to claim 1 , further comprising:

7. The substrate processing method according to claim 1, wherein the pressure inside the processing vessel is 20 Pa to 100 Pa in the reducing step.

8. The substrate processing method according to any one of claims 1 to 5, wherein the conductive layer is made of any one of Cu, Al, Ru, Ti, Mo, Co, W, and Ta.

9. The substrate processing method according to any one of claims 1 to 5, wherein the semiconductor layer is made of Si.

10. The substrate processing method according to claim 1, wherein in the step of forming the stabilizing layer, a temperature inside the processing vessel is from room temperature to 350° C.

11. The substrate processing method according to claim 10, wherein in the step of forming the stabilizing layer, a temperature inside the processing vessel is from room temperature to 100° C.

12. A substrate processing apparatus comprising: a processing vessel; a gas supply unit that supplies gas into the processing vessel; a power source that supplies high-frequency power into the processing vessel; and a control unit, wherein the control unit controls the following: preparing a substrate having a conductive layer or a semiconductor layer in the processing vessel; supplying a first gas containing hydrogen and nitrogen from the gas supply unit into the processing vessel and exposing the substrate to plasma generated from the first gas, thereby reducing a surface of the conductive layer or the semiconductor layer; supplying a second gas containing hydrogenated silicon or alkylated aluminum from the gas supply unit and exposing the reduced conductive layer or the semiconductor layer to the second gas, thereby adsorbing silicon or aluminum onto the conductive layer or the semiconductor layer to form a stabilizing layer.

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