阅读说明：本技术 半导体装置的制造方法、基板处理装置和程序 (Method for manufacturing semiconductor device, substrate processing apparatus, and program ) 是由 片冈良太 平松宏朗 石桥清久 于 2019-09-18 设计创作，主要内容包括：本发明提供一种技术,具有：通过将以下循环进行预定次数,从而在下述基板上形成含有下述第一元素和下述第二元素的膜的工序,所述循环为依次进行(a)对处理室内的基板供给含有第一元素的第一原料气体的工序,(b)对基板供给含有第一元素且热分解温度比第一原料气体低的第二原料气体的工序和(c)对基板供给含有与第一元素不同的第二元素的反应气体的工序。(The present invention provides a technique comprising: a method for forming a film containing a first element and a second element on a substrate includes a step of sequentially performing (a) a step of supplying a first source gas containing the first element to the substrate in a processing chamber, (b) a step of supplying a second source gas containing the first element and having a lower thermal decomposition temperature than the first source gas to the substrate, and (c) a step of supplying a reaction gas containing a second element different from the first element to the substrate, by performing a cycle of (a) supplying the first source gas containing the first element to the substrate and (b) supplying the reaction gas containing the second element to the substrate.)

1. A method for manufacturing a semiconductor device includes: a step of forming a film containing a first element and a second element on a substrate by performing the following cycle a predetermined number of times,

the cycle is a process of sequentially performing (a) a process of supplying a first source gas containing a first element to a substrate in a processing chamber, (b) a process of supplying a second source gas containing the first element and having a lower thermal decomposition temperature than the first source gas to the substrate, and (c) a process of supplying a reaction gas containing a second element different from the first element to the substrate.

2. The method for manufacturing a semiconductor device according to claim 1,

setting the temperature of the substrate in (a) to a temperature lower than the temperature at which thermal decomposition of the first source gas occurs when the first source gas is present alone in the processing chamber,

when the second source gas is present alone in the processing chamber, the temperature of the substrate in (b) is set to a temperature higher than the temperature at which the second source gas is thermally decomposed.

3. The method for manufacturing a semiconductor device according to claim 1 or claim 2,

(a) wherein a first layer containing the first element is formed with a thickness of less than 1 atomic layer,

(b) in (2), the second layer containing the first element is formed in a thickness of more than 1 atomic layer.

4. The method for manufacturing a semiconductor device according to claim 3,

the amount of bonds between the first element and the first element contained in the second layer is made larger than the amount of bonds between the first element and the first element contained in the first layer.

5. The method for manufacturing a semiconductor device according to any one of claims 1 to 4,

allowing the temperature of the substrate in (a) and the temperature of the substrate in (b) to be substantially the same temperature.

6. The method for manufacturing a semiconductor device according to any one of claims 1 to 5,

controlling a composition ratio in the film as a ratio of a content of the first element to a content of the second element by adjusting a ratio B/A of a supply amount B of the second raw material gas per 1 cycle to a supply amount A of the first raw material gas per 1 cycle.

7. The method for manufacturing a semiconductor device according to claim 6,

controlling the composition ratio of the film toward a trend toward approaching a stoichiometric composition of a compound composed of the first element and the second element by decreasing the B/A ratio,

the composition ratio of the film is controlled toward a tendency to make the content ratio of the first element larger than the stoichiometric composition by increasing the B/a ratio.

8. The method for manufacturing a semiconductor device according to claim 6 or claim 7,

by adjusting the supply time T of the second raw material gas per 1 cycle_BRelative to the supply time T of the first raw material gas in each 1 cycle_ARatio T of_B/T_ATo control the composition ratio of the film.

9. The method for manufacturing a semiconductor device according to any one of claims 6 to 8, wherein,

by adjusting the supply flow rate F of the second raw material gas_BA supply flow rate F with respect to the first raw material gas_ARatio F of_B/F_ATo control the composition ratio of the film.

10. The method for manufacturing a semiconductor device according to any one of claims 1 to 9,

by adjusting the pressure P in the process chamber in (b)_BTo control a composition ratio as a ratio of a content of the first element to a content of the second element in the film。

11. The method for manufacturing a semiconductor device according to any one of claims 1 to 10,

the first source gas and the second source gas are respectively different from each other in terms of a halosilane-based gas.

12. The method for manufacturing a semiconductor device according to any one of claims 1 to 10,

as the second source gas, a gas containing at least either a hydrogen silicide-based gas or an aminosilane-based gas is used.

13. The method for manufacturing a semiconductor device according to any one of claims 1 to 12,

as the reaction gas, a gas containing at least either of a nitriding gas or an oxidizing gas is used.

14. The method for manufacturing a semiconductor device according to any one of claims 1 to 13,

in the above cycle, the execution period of (a) and the execution period of (b) are not overlapped.

15. The method for manufacturing a semiconductor device according to any one of claims 1 to 13,

when the loop is performed, at least a part of the execution period of (a) and the execution period of (b) are overlapped.

16. The method for manufacturing a semiconductor device according to any one of claims 1 to 15,

further having (c) before performing said cycle.

17. A substrate processing apparatus includes:

a processing chamber for accommodating the substrate therein,

a first source gas supply system configured to supply a first source gas containing a first element into the processing chamber,

a second source gas supply system configured to supply a second source gas containing the first element and having a lower thermal decomposition temperature than the first source gas into the processing chamber,

a reaction gas supply system for supplying a reaction gas containing a second element different from the first element into the processing chamber, and

a controller configured to control the first source gas supply system, the second source gas supply system, and the reaction gas supply system such that a process of forming a film containing the first element and the second element on the substrate is performed in the process chamber by performing a cycle of (a) a process of supplying the first source gas to the substrate, (b) a process of supplying the second source gas to the substrate, and (c) a process of supplying the reaction gas to the substrate in this order, a predetermined number of times.

18. A program for causing, by a computer, a substrate processing apparatus to execute:

a step of forming a film containing a first element and a second element described below on a substrate described below by performing the following cycle a predetermined number of times in a processing chamber of the substrate processing apparatus,

the cycle is a process of sequentially performing (a) a process of supplying a first source gas containing a first element to a substrate, (b) a process of supplying a second source gas containing the first element and having a lower thermal decomposition temperature than the first source gas to the substrate, and (c) a process of supplying a reaction gas containing a second element different from the first element to the substrate.

Technical Field

The present disclosure relates to a method of manufacturing a semiconductor device, a substrate processing apparatus, and a program.

Background

As one step of a manufacturing process of a semiconductor device, a process of forming a film on a substrate may be performed (see, for example, patent documents 1 and 2).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2016-

Patent document 2: japanese patent laid-open publication No. 2017-097017

Disclosure of Invention

Problems to be solved by the invention

An object of the present disclosure is to provide a technique capable of improving the characteristics of a film formed on a substrate.

Means for solving the problems

According to one aspect of the present disclosure, there is provided a technique for forming a film containing a first element and a second element on a substrate by performing, a cycle of (a) supplying a first source gas containing the first element to the substrate in a processing chamber, (b) supplying a second source gas containing the first element and having a lower thermal decomposition temperature than the first source gas to the substrate, and (c) supplying a reaction gas containing a second element different from the first element to the substrate, in this order, a predetermined number of times.

Effects of the invention

According to the present disclosure, a technique capable of improving the characteristics of a film formed on a substrate can be provided.

Drawings

FIG. 1 is a schematic configuration diagram of a vertical processing furnace of a substrate processing apparatus suitably used in one embodiment of the present disclosure, and is a diagram showing a portion of the processing furnace in a vertical sectional view.

FIG. 2 is a schematic configuration diagram of a vertical processing furnace of a substrate processing apparatus suitably used in one embodiment of the present disclosure, and is a diagram showing a portion of the processing furnace in a sectional view taken along line A-A of FIG. 1.

Fig. 3 is a schematic configuration diagram of a controller of a substrate processing apparatus suitably used in one embodiment of the present disclosure, and a control system of the controller is shown as a block diagram.

Fig. 4 is a diagram showing a flow in a substrate processing process according to one embodiment of the present disclosure.

[ FIG. 5] is a view showing the timing of gas supply in a film formation process according to one embodiment of the present disclosure.

Fig. 6 is a diagram showing a modification of the timing of gas supply in the film formation process according to one embodiment of the present disclosure.

In fig. 7, (a) is a partial enlarged view of the substrate surface after the first raw material gas is supplied by performing step a, (b) is a partial enlarged view of the substrate surface after the second raw material gas is supplied by performing step b after performing step a, and (c) is a partial enlarged view of the substrate surface after the reaction gas is supplied by performing step c after performing step b.

FIG. 8 is a graph showing the evaluation results of a film formed on a substrate.

FIG. 9 is a view showing the evaluation results of a film formed on a substrate.

Detailed Description

< one aspect of the present disclosure >

Hereinafter, one embodiment of the present disclosure will be described mainly with reference to fig. 1 to 5 and 7.

(1) Structure of substrate processing apparatus

As shown in fig. 1, the processing furnace 202 has a heater 207 as a heating means (temperature adjustment unit). The heater 207 has a cylindrical shape and is vertically installed by being supported by a holding plate. The heater 207 also functions as an activation mechanism (excitation unit) for activating (exciting) the gas by heat.

Inside the heater 207, a reaction tube 203 is disposed concentrically with the heater 207. The reaction tube 203 is made of, for example, quartz (SiO)₂) Or a heat-resistant material such as silicon carbide (SiC), and is formed into a cylindrical shape having a closed upper end and an open lower end. In the reverse directionThe hollow portion of the cylinder of the tube 203 forms the processing chamber 201. The processing chamber 201 is configured to accommodate a wafer 200 as a substrate. The wafer 200 is processed in the processing chamber 201.

In the processing chamber 201, the nozzles 249a and 249b are provided so as to penetrate through the lower side wall of the reaction tube 203. The nozzles 249a and 249b are connected to the gas supply pipes 232a and 232b, respectively.

Mass Flow Controllers (MFCs) 241a and 241b as flow rate controllers (flow rate control units) and valves 243a and 243b as on-off valves are provided in the gas supply pipes 232a and 232b in this order from the upstream side of the gas flow. A gas supply pipe 232c is connected to the gas supply pipe 232a on the downstream side of the valve 243 a. In the gas supply pipe 232c, an MFC241c and a valve 243c are provided in this order from the upstream side of the gas flow. Gas supply pipes 232e and 232d are connected to the gas supply pipes 232a and 232b on the downstream side of the valves 243a and 243b, respectively. In the gas supply pipes 232e,232d, MFCs 241e,241d and valves 243e,243d are provided in this order from the upstream side of the gas flow, respectively.

As shown in fig. 2, in the annular space between the inner wall of the reaction tube 203 and the wafer 200 in a plan view, the nozzles 249a and 249b are provided along the inner wall of the reaction tube 203 from the lower portion toward the upper portion and upward in the arrangement direction of the wafers 200. That is, the nozzles 249a and 249b are provided along the wafer arrangement region in a region laterally surrounding the wafer arrangement region in which the wafers 200 are arranged. Gas supply holes 250a and 250b for supplying gas are provided in the side surfaces of the nozzles 249a and 249b, respectively. The gas supply holes 250a and 250b are opened toward the center of the reaction tube 203, respectively, and can supply gas toward the wafer 200. A plurality of gas supply holes 250a,250b are provided from the lower portion to the upper portion of the reaction tube 203.

A first source gas containing a first element, for example, a halosilane-based gas containing silicon (Si) as the first element and a halogen element is supplied into the processing chamber 201 from the gas supply pipe 232a through the MFC241a, the valve 243a, and the nozzle 249 a. The raw material gas is a gaseous raw material, for example, a gas obtained by gasifying a raw material that is in a liquid state at normal temperature and normal pressure, or a gas at normal temperature and normal pressureThe following are gaseous raw materials and the like. Halosilanes are silanes having a halogen group. The halogen group includes a chlorine group, a fluorine group, a bromine group, an iodine group and the like. That is, the halogen group includes halogen elements such as chlorine (Cl), fluorine (F), bromine (Br), and iodine (I). As the halosilane-based gas, for example, a raw material gas containing Si and Cl, that is, a chlorosilane-based gas can be used. As the first raw material gas, a chlorosilane-based gas having 1 Si atom in 1 molecule, for example, tetrachlorosilane (SiCl), can be used₄) A gas. SiCl₄The gas functions as an Si source in a film formation process described later. In the present specification, when the first source gas is present alone in the processing chamber 201, the temperature at which the first source gas is thermally decomposed may be referred to as a first temperature. Using SiCl₄The first temperature when the gas is used as the first raw material gas is a predetermined temperature in a range of 800 ℃ or higher.

A second source gas containing the first element and having a lower thermal decomposition temperature than the first source gas, for example, a halosilane-based gas containing Si as the first element and a halogen element is supplied into the processing chamber 201 from the gas supply pipe 232c through the MFC241c, the valve 243c, and the nozzle 249 a. As the second raw material gas, a chlorosilane-based gas having 2 or more Si atoms contained in 1 molecule and having an Si — Si bond, for example, hexachlorodisilane (Si), can be used₂Cl₆For short: HCDS) gas. Si₂Cl₆The gas functions as an Si source in a film formation process described later. In the present specification, when the second source gas is present alone in the processing chamber 201, the temperature at which the second source gas is thermally decomposed may be referred to as a second temperature. Using Si₂Cl₆The second temperature when the gas is used as the second raw material gas is a predetermined temperature in a range of 500 ℃ or higher.

A reaction gas containing a second element different from the first element, for example, a nitriding gas containing nitrogen (N) as the second element is supplied into the processing chamber 201 from the gas supply pipe 232b through the MFC241b, the valve 243b, and the nozzle 249 b. As the nitriding gas, for example, ammonia (NH) can be used₃) A gas. NH (NH)₃The gas functions as an N source in a film formation process described later.

Nitrogen (N) as an inert gas is supplied from the gas supply pipes 232d and 232e into the processing chamber 201 through the MFCs 241d and 241e, the valves 243d and 243e, the gas supply pipes 232a and 232b, and the nozzles 249a and 249b, respectively₂) A gas. N is a radical of₂The gas functions as a purge gas, a carrier gas, a diluent gas, or the like.

When the above-described gases are introduced from the respective gas supply pipes, the first source gas supply system is mainly constituted by the gas supply pipe 232a, the MFC241a, and the valve 243 a. The second source gas supply system is mainly composed of a gas supply pipe 232c, an MFC241c, and a valve 243 c. The reaction gas supply system is mainly composed of a gas supply pipe 232b, an MFC241b, and a valve 243 b. The inert gas supply system is mainly constituted by gas supply pipes 232d,232e, MFCs 241d,241e, and valves 243d,243 e.

Any or all of the various supply systems described above may be configured as an integrated supply system 248 in which valves 243a to 243e, MFCs 241a to 241e, and the like are integrated. The integrated supply system 248 is connected to the gas supply pipes 232a to 232e, and is configured such that the controller 121, which will be described later, controls operations of supplying various gases into the gas supply pipes 232a to 232e, that is, opening and closing operations of the valves 243a to 243e, flow rate adjustment operations by the MFCs 241a to 241e, and the like. The integrated supply system 248 is configured as an integrated unit or a detachable integrated unit, and can be attached to and detached from the gas supply pipes 232a to 232e and the like on an integrated unit basis, and maintenance, replacement, addition, and the like of the integrated supply system 248 can be performed on an integrated unit basis.

An exhaust pipe 231 for exhausting the atmosphere in the processing chamber 201 is connected to a lower portion of the sidewall of the reaction tube 203. The exhaust pipe 231 is connected to a vacuum pump 246 as a vacuum exhaust device via a Pressure sensor 245 as a Pressure detector (Pressure detector) for detecting the Pressure in the processing chamber 201 and an APC (automatic Pressure Controller) valve 244 as a Pressure regulator (Pressure adjuster). The APC valve 244 is configured to be able to perform vacuum evacuation and vacuum evacuation stop in the processing chamber 201 by opening and closing a valve in a state where the vacuum pump 246 is operated, and to be able to adjust the pressure in the processing chamber 201 by adjusting the valve opening degree based on pressure information detected by the pressure sensor 245 in a state where the vacuum pump 246 is operated. The exhaust system is mainly composed of an exhaust pipe 231, a pressure sensor 245, and an APC valve 244. It is also contemplated that the vacuum pump 246 may be incorporated into the exhaust system.

A sealing cap 219 serving as a furnace opening lid body capable of hermetically closing the lower end opening of the reaction tube 203 is provided below the reaction tube 203. The seal cap 219 is made of a metal material such as SUS, and is formed in a disk shape. An O-ring 220 as a sealing member abutting against the lower end of the reaction tube 203 is provided on the upper surface of the sealing cap 219. A rotation mechanism 267 for rotating the wafer cassette 217 described later is provided below the seal cap 219. The rotary shaft 255 of the rotary mechanism 267 penetrates the seal cap 219 and is connected to the wafer cassette 217. The rotating mechanism 267 is configured to rotate the wafer 200 by rotating the pod 217. The sealing cap 219 is configured to be vertically lifted by a cassette lifter 115 as a lifting mechanism provided outside the reaction tube 203. The cassette lifter 115 is configured as a transfer device (transfer mechanism) that moves the wafer 200 into the processing chamber 201 and out of the processing chamber 201 (transfers) by lifting and lowering the seal cap 219.

The wafer cassette 217 as a substrate support member is configured to support a plurality of wafers 200 (for example, 25 to 200 wafers) in a vertical direction in a horizontal posture with their centers aligned, and in multiple stages, that is, at intervals. The wafer cassette 217 is made of a heat-resistant material such as quartz or SiC. A heat shield plate 218 made of a heat-resistant material such as quartz or SiC is supported in multiple stages in a horizontal posture at a lower portion of the wafer cassette 217

A temperature sensor 263 as a temperature detector is provided in the reaction tube 203. The temperature inside the processing chamber 201 is set to a desired temperature distribution by adjusting the energization of the heater 207 based on the temperature information detected by the temperature sensor 263. The temperature sensor 263 is disposed along the inner wall of the reaction tube 203.

As shown in fig. 3, the controller 121 as a control Unit (control means) is configured as a computer having a CPU (Central Processing Unit) 121a, a RAM (Random Access Memory) 121b, a storage device 121c, and an I/O interface 121 d. The RAM121b, the storage device 121c, and the I/O interface 121d are configured to be able to exchange data with the CPU121a via the internal bus 121 e. The controller 121 is connected to an input/output device 122 configured as a touch panel or the like, for example.

The storage device 121c is configured by, for example, a flash memory, an HDD (Hard Disk Drive), or the like. The memory device 121c stores a control program for controlling the operation of the substrate processing apparatus, and can read out a process recipe in which the process, conditions, and the like of the film formation process described later are described. The process recipe combines each process in the film formation process described later so that the controller 121 executes the process and obtains a predetermined result, and functions as a program. Hereinafter, the process recipe, the control program, and the like are also referred to simply as a program. In addition, the process recipe is also referred to as recipe. When the term "program" is used in the present specification, the case where only a single recipe is used, the case where only a single control program is used, and the case where both the recipes are used are included. The RAM121b is configured as a storage area (work area) for temporarily storing programs, data, and the like read by the CPU121 a.

The I/O interface 121d is connected to the MFCs 241a to 241e, the valves 243a to 243e, the pressure sensor 245, the APC valve 244, the vacuum pump 246, the temperature sensor 263, the heater 207, the rotation mechanism 267, the cassette lifter 115, and the like.

The CPU121a is configured to read out and execute a control program from the storage device 121c, and read out a recipe from the storage device 121c in response to input of an operation command from the input/output device 122, and the like. The CPU121a is also configured to control flow rate adjustment operations of the respective gases by the MFCs 241a to 241e, opening and closing operations of the valves 243a to 243e, opening and closing operations of the APC valve 244, pressure adjustment operations by the APC valve 244 based on the pressure sensor 245, start and stop of the vacuum pump 246, temperature adjustment operations of the heater 207 based on the temperature sensor 263, rotation and rotation speed adjustment operations of the cassette 217 by the rotation mechanism 267, and lifting and lowering operations of the cassette 217 by the cassette lifter 115, in accordance with the contents of the read recipe.

The controller 121 can be configured by installing the above-described program stored in the external storage device 123 into a computer. The external storage device 123 includes, for example, a magnetic disk such as an HDD, an optical disk such as a CD, an optical magnetic disk such as an MO, a semiconductor memory such as a USB memory, and the like. The storage device 121c and the external storage device 123 are configured as a computer-readable recording medium. Hereinafter, these will be collectively referred to simply as recording media. The present specification, when using the term "recording medium", includes a case where only the storage device 121c is provided separately, a case where only the external storage device 123 is provided separately, or a case where both are provided. Note that the program may be provided to the computer by using the internet or a dedicated communication method without using an external storage device.

(2) Substrate processing procedure

As one step of a manufacturing process of a semiconductor device using the substrate processing apparatus, a substrate processing sequence example (that is, a film formation sequence example) in which a film is formed on a wafer 200 as a substrate will be described with reference to fig. 4, 5, and 7. In the following description, the operations of the respective parts constituting the substrate processing apparatus are controlled by the controller 121.

In the film formation sequence shown in fig. 4 and 5, SiCl as a first source gas is supplied to the wafer 200 in the process chamber 201 in sequence₄Step a of gas supply of Si as a second source gas to the wafer 200₂Cl₆Step b of gas and supply of NH as a reaction gas to the wafer 200₃The gas step c is performed as a cycle, and a silicon nitride film (SiN film) which is a film containing Si and N is formed on the wafer 200 by performing the cycle a predetermined number of times (N times, N being an integer of 1 or more). In fig. 5, the execution periods of steps a, b, and c are denoted as a, b, and c, respectively.

For convenience, the film formation sequence shown in fig. 4 and 5 may be as follows. The same expressions are used in the following description of other embodiments and the like.

In the present specification, the term "wafer" includes a case of "wafer itself" and a case of "a laminated body of a wafer and a predetermined layer, film, or the like formed on the surface of the wafer". In the present specification, the term "wafer surface" includes a case of "the surface of the wafer" and a case of "the surface of a predetermined layer, film, or the like formed on the wafer". In the present specification, the phrase "forming a predetermined layer on a wafer" includes a case where a predetermined layer is directly formed on the surface of a wafer itself, and a case where a predetermined layer is formed on a layer or the like formed on a wafer. In the present specification, the term "substrate" is used in the same sense as the term "wafer".

(wafer mounting and wafer cassette mounting)

A plurality of wafers 200 are loaded into the cassette 217 (wafer loading). Then, as shown in fig. 1, the cassette 217 supporting a plurality of wafers 200 is lifted by the cassette lifter 115 and carried into the processing chamber 201 (cassette mounting). In this state, the seal cap 219 closes the lower end of the reaction tube 203 via the O-ring 220.

(pressure adjustment and temperature adjustment)

Vacuum evacuation (vacuum evacuation) is performed by the vacuum pump 246 so that the space in the process chamber 201, i.e., the wafer 200, is brought to a desired process pressure (vacuum degree). At this time, the pressure in the processing chamber 201 is measured by the pressure sensor 245, and the APC valve 244 is feedback-controlled based on the measured pressure information. The wafer 200 in the processing chamber 201 is heated by the heater 207 to a desired processing temperature (film formation temperature). At this time, the energization of the heater 207 is feedback-controlled based on the temperature information detected by the temperature sensor 263 so that a desired temperature distribution is achieved in the processing chamber 201. Further, the wafer 200 is rotated by the rotating mechanism 267. The operation of the vacuum pump 246, the heating of the wafer 200, and the rotation are continued at least until the end of the processing of the wafer 200.

(film formation treatment)

Then, the following steps a to c are performed in this order.

[ step a ]

In this step, SiCl is supplied to the wafer 200 in the processing chamber 201₄A gas. Specifically, the valve 243a is opened, and SiCl is flowed into the gas supply pipe 232a₄A gas. SiCl₄The gas is supplied into the processing chamber 201 through the nozzle 249a with the flow rate thereof adjusted by the MFC241a, and is exhausted through the exhaust pipe 231. At this time, SiCl is supplied to the wafer 200₄A gas. At the same time, the valves 243d and 243e are opened, and N flows into the gas supply pipes 232d and 232e₂A gas. N is a radical of₂The gas flow is regulated by MFCs 241d,241 e. Adjusted N of flow₂Gas and SiCl₄The gases are supplied into the processing chamber 201 and exhausted through the exhaust pipe 231.

The processing conditions in this step are exemplified by:

SiCl₄gas supply flow rate: 1 to 2000sccm, preferably 100 to 1000sccm,

N₂gas supply flow rate (each gas supply pipe): 100 to 20000sccm,

supply time of each gas: 10 to 300 seconds, preferably 30 to 120 seconds,

treatment temperature (lower temperature than first temperature, preferably lower temperature than first temperature and higher temperature than second temperature): 400-800 ℃, preferably 500-800 ℃, more preferably 600-750 ℃,

treatment pressure: 1 to 2666Pa, preferably 10 to 1333 Pa.

In the present specification, the numerical range of "400 to 800 ℃ means that the lower limit value and the upper limit value are included in the range. Therefore, "400 to 800 ℃ means" 400 ℃ to 800 ℃. The same applies to other numerical ranges.

In this embodiment, as the pretreatment of this step, NH is supplied to the wafer 200 first₃Gas, etc. reaction gas. By supplying NH to the wafer 200 in a preflow₃Gas capable of being on the wafer200 are formed with adsorption sites by hydrogen (H) on the surface, and Si atoms are easily adsorbed (i.e., highly reactive with Si atoms) in this step and in step b described later. The process of the preflow can be performed, for example, in the same manner as in step c described below.

Under the above conditions, SiCl can be reacted with₄A part of the Si — Cl bonds in the wafer 200 are cut off, so that Si which has become unbound bonds is adsorbed to the adsorption sites on the surface of the wafer 200. Further, under the above conditions, SiCl can be reacted₄The non-cleaved Si-Cl bond in (1) is maintained as it is. For example, in the formation of SiCl₄In a state where 3 of the 4 bonds of Si in (2) are respectively bonded to Cl, Si having unbound bonds can be adsorbed to the adsorption sites on the surface of the wafer 200. In addition, since Cl, which is not cut by Si adsorbed from the surface of the wafer 200 and is held, prevents the Si from bonding with other Si having an unbonded bond, it is possible to avoid a large amount of Si from being deposited on the wafer 200. Cl cleaved from Si constitutes HCl, Cl₂And the gaseous substances are exhausted from the exhaust pipe 231. If there are no more adsorption sites remaining on the surface of the wafer 200 as the adsorption reaction of Si proceeds, the adsorption reaction is saturated, but in this step, SiCl is stopped before the adsorption reaction is saturated₄The gas is desirably supplied so that the adsorption sites remain.

As a result of this, on the wafer 200, as a first layer, a layer containing Si and Cl, that is, a Si-containing layer containing Cl is formed in a substantially uniform thickness of less than 1 atomic layer thickness. Fig. 7 (a) shows a partially enlarged view of the surface of the wafer 200 on which the first layer is formed. Here, a layer less than 1 atomic layer thick means an atomic layer formed discontinuously, and a layer 1 atomic layer thick means an atomic layer formed continuously. Further, a layer that is less than 1 atomic layer thick is substantially uniform meaning that atoms are adsorbed at a substantially uniform density on the surface of the wafer 200. Since the first layer is formed with a substantially uniform thickness on the wafer 200, the step coverage property and the uniformity of the film thickness in the wafer plane are excellent.

If the processing temperature is less than 400 ℃, Si becomes difficult to adsorb on the wafer 200, and the first layer may be difficult to form. By setting the processing temperature to 400 ℃ or higher, the first layer can be formed on the wafer 200. The above-mentioned effects can be surely obtained by setting the treatment temperature to 500 ℃ or higher. The above-mentioned effects can be more reliably obtained by setting the treatment temperature to 600 ℃ or higher.

If the treatment temperature exceeds 800 ℃, it is difficult to maintain SiCl as it is₄In which the Si-Cl bond is not cleaved, and SiCl₄The thermal decomposition rate of (2) is increased, and as a result, Si is sometimes multiply deposited on the wafer 200, and it becomes difficult to form a Si-containing layer having a substantially uniform thickness of less than 1 atomic layer as the first layer. By setting the process temperature to 800 ℃ or lower, a substantially uniform thickness Si-containing layer having a thickness of less than 1 atomic layer can be formed as the first layer. The above-mentioned effects can be obtained with certainty by setting the treatment temperature to 750 ℃ or lower.

After the first layer is formed on the wafer 200, the valve 243a is closed to stop the SiCl supply into the processing chamber 201₄A gas. Then, the inside of the processing chamber 201 is evacuated to remove the gas and the like remaining in the processing chamber 201 from the inside of the processing chamber 201. At this time, the valves 243d and 243e are still kept open, and the supply of N as the inert gas into the processing chamber 201 is maintained₂A gas. N is a radical of₂The gas functions as a purge gas, and thus, the effect of removing gas and the like remaining in the processing chamber 201 from the processing chamber 201 can be improved.

As the first raw material gas, in addition to SiCl₄As gases, dichlorosilane (SiH) can be used₂Cl₂For short: DCS) gas, trichlorosilane (SiHCl)₃For short: TCS) gas, and the like.

As inert gases, other than N₂In addition to the gas, an inert gas such as Ar gas, He gas, Ne gas, or Xe gas can be used. This is also the same in steps b and c described later.

[ step b ]

In this step, Si is supplied to the wafer 200 in the processing chamber 201, i.e., the first layer formed on the wafer 200₂Cl₆A gas. Specifically, the valve is openedA gate 243c for flowing Si into the gas supply pipe 232a₂Cl₆A gas. Si₂Cl₆The gas is controlled by the MFC241c, supplied into the processing chamber 201 through the nozzle 249a, and exhausted through the exhaust pipe 231. At this time, Si is supplied to the wafer 200₂Cl₆A gas.

The processing conditions in this step are exemplified by:

Si₂Cl₆gas supply flow rate: is 1 to 2000sccm, preferably 100 to 1000sccm,

Si₂Cl₆gas supply time: 0.5 to 60 seconds, preferably 1 to 30 seconds,

treatment temperature (higher temperature than the second temperature, preferably higher temperature than the second temperature and lower temperature than the first temperature): is 500 to 1000 ℃, preferably 600 to 800 ℃, and more preferably 650 to 750 ℃.

The other processing conditions were the same as those in step a.

Under the above conditions, Si can be reacted₂Cl₆Most of the molecular structure of the gas is thermally decomposed, whereby Si that has become unbound bonds reacts with the adsorption sites on the surface of the wafer 200 remaining without forming the first layer in step a, and is adsorbed to the surface of the wafer 200. On the other hand, since no adsorption site exists at the portion where the first layer is formed, adsorption of Si to the first layer is suppressed. As a result, in this step, the Si-containing layer as the second layer is formed in a substantially uniform thickness on the basis of the first layer formed in a substantially uniform thickness. Furthermore, via Si₂Cl₆Si having unbonded bonds are bonded to each other to form Si — Si bonds. By reacting these Si — Si bonds with adsorption sites and the like remaining on the surface of the wafer 200, Si — Si bonds can be contained in the second layer, and a layer in which Si is multiply deposited can be formed. That is, by this step, the amount (content ratio) of Si — Si bonds contained in the second layer can be made larger than the amount (content ratio) of Si — Si bonds contained in the first layer. Cl cleaved from Si forms HCl, Cl₂And the gaseous substances are exhausted from the exhaust pipe 231.

In order to make the amount of Si-Si bonds contained in the second layer larger than the amount of Si-Si bonds contained in the first layer by this step, it is appropriate that the thermal decomposition temperature of the second raw material gas is lower than the thermal decomposition temperature of the first raw material gas, as described above. In other words, it is desirable that the second raw material gas be a gas that forms Si — Si bonds more easily under the same conditions than the first raw material gas. For example, the second source gas preferably has a larger composition ratio of Si to halogen elements such as Cl in its molecules than the first source gas, because the second source gas contains Si — Si bonds in its molecules. In this way, the selection of the process conditions such as the process temperature in each step and the selection of the first source gas and the second source gas can be performed so that Si — Si bonds that react with adsorption sites and the like remaining on the wafer surface are more easily formed in this step than in step a.

As a result, in this step, as the second layer, the Si-containing layer having a substantially uniform thickness exceeding the first layer is formed. In the present embodiment, particularly, the Si-containing layer having a substantially uniform thickness of more than 1 atomic layer is formed as the second layer from the viewpoint of improving the film formation rate. Fig. 7 (b) shows a partially enlarged view of the surface of the wafer 200 on which the second layer is formed. In this specification, the second layer means a Si-containing layer formed on the wafer 200 by performing steps a and b once.

If the treatment temperature is less than 500 ℃, Si₂Cl₆The gas is difficult to thermally decompose, and sometimes it is difficult to form the second layer. The second layer can be formed on the first layer by setting the treatment temperature to 500 ℃ or higher. The above-mentioned effects can be surely obtained by setting the treatment temperature to 600 ℃ or higher. The above-mentioned effects can be more surely obtained by setting the treatment temperature to 650 ℃ or higher.

If the treatment temperature exceeds 1000 deg.C, Si is present₂Cl₆Since the thermal decomposition of the gas is excessive and the deposition of Si that is not self-saturated tends to proceed rapidly, it may be difficult to form the second layer substantially uniformly. Si can be suppressed by setting the treatment temperature to 1000 ℃ or lower₂Cl₆The second layer can be formed substantially uniformly by controlling the deposition of Si that is not self-saturated by excessive thermal decomposition of the gas. The above-mentioned effects can be surely obtained by setting the treatment temperature to 800 ℃ or lower. The above-mentioned effects can be more reliably obtained by setting the treatment temperature to 750 ℃ or lower.

In addition, the temperature conditions in steps a and b are desirably substantially the same. Thus, it is not necessary to change the temperature of the wafer 200, that is, to change the temperature in the processing chamber 201 (change the set temperature of the heater 207) between steps a and b, and it is not necessary to wait for the wafer 200 to reach a stable temperature between steps, and throughput (throughput) of substrate processing can be improved. Therefore, in both steps a and b, the temperature of the wafer 200 may be set to a predetermined temperature within a range of, for example, 500 to 800 ℃, preferably 600 to 800 ℃, and more preferably 650 to 750 ℃. In the present embodiment, the temperature conditions in steps a and b are substantially the same, and the temperature conditions and the first and second source gases are selected so that thermal decomposition of the first source gas does not substantially occur (i.e., is suppressed) in step a, and thermal decomposition of the second source gas occurs (i.e., is promoted) in step b.

After the second layer is formed on the wafer 200, the valve 243c is closed to stop the supply of Si into the processing chamber 201₂Cl₆A gas. Then, the gas and the like remaining in the processing chamber 201 are removed from the processing chamber 201 by the same processing procedure and processing conditions as those in the step a for removing the residual gas.

As the second raw material gas, Si is removed₂Cl₆As gases, monosilane (SiH) can be used₄And abbreviation: a hydrogen silicide-based source gas such as MS) gas, tris (dimethylamino) silane (Si [ N (CH) ]₃)₂]₃H, abbreviation: 3DMAS) gas, bis-diethylaminosilane (SiH)₂[N(C₂H₅)₂]₂For short: BDEAS) gas, and the like. By using a non-halogen gas as the second source gas, it is possible to prevent halogen from being mixed into the SiN film finally formed on the wafer 200.

[ step c ]

In this step, NH is supplied to the wafer 200 in the processing chamber 201, that is, a layer in which the first layer and the second layer formed on the wafer 200 are laminated₃Gas (es). Specifically, the valve 243b is opened, and NH flows into the gas supply pipe 232b₃A gas. NH (NH)₃The gas is controlled by the MFC241b, supplied into the processing chamber 201 through the nozzle 249b, and exhausted through the exhaust pipe 231. At this time, NH is supplied to the wafer 200₃A gas.

The processing conditions in this step are exemplified by:

NH₃gas supply flow rate: 100 to 10000sccm, preferably 1000 to 5000sccm,

NH₃gas supply time: 1 to 120 seconds, preferably 10 to 60 seconds,

treatment pressure: 1 to 4000Pa, preferably 10 to 1000 Pa.

The other processing conditions were the same as those in step a. In particular, the temperature conditions in step c are preferably the same as those in steps a and b from the viewpoint of improving the productivity of the film formation process, but may be different from those in steps a and b.

Under the above conditions, at least a part of the second layer can be nitrided. The Cl contained in the second layer constitutes HCl or Cl₂And the gaseous substances are exhausted from the exhaust pipe 231.

As a result, an SiN layer containing Si and N is formed as a third layer on the wafer 200. Fig. 7 (c) shows a partially enlarged view of the surface of the wafer 200 on which the third layer is formed.

After the third layer is formed on the wafer 200, the valve 243b is closed to stop the supply of NH into the processing chamber 201₃A gas. Then, the gas and the like remaining in the processing chamber 201 are removed from the processing chamber 201 by the same processing procedure and processing conditions as those in the step a for removing the residual gas.

As reaction gas, except NH₃As a gas, diazene (N) can be used₂H₂) Gas, hydrazine (N)₂H₄) Gas, N₃H₈A hydrogen nitride-based gas such as a gas.

[ predetermined number of executions ]

By setting the steps a to c to 1 cycle and performing the cycle a predetermined number of times (n times, n being an integer of 1 or more), an SiN film having a predetermined composition ratio and a predetermined film thickness can be formed on the wafer 200. The above cycle is preferably repeated a plurality of times. That is, the SiN layer formed per 1 cycle is preferably made to have a thickness smaller than a desired film thickness, and the above cycle is preferably repeated a plurality of times until the desired film thickness is reached.

(post purge and atmospheric pressure recovery)

After the film formation process is completed, N as an inert gas is supplied into the process chamber 201 through the gas supply pipes 232d and 232e, respectively₂The gas is exhausted through the exhaust pipe 231. Thereby, the inside of the processing chamber 201 is purged, and the gas, reaction by-products, and the like remaining in the processing chamber 201 are removed from the inside of the processing chamber 201 (post-purge). Then, the atmosphere in the processing chamber 201 is replaced with an inert gas (inert gas replacement), and the pressure in the processing chamber 201 is returned to normal pressure (atmospheric pressure return).

(wafer cassette unload and wafer Release)

Then, the sealing cap 219 is lowered by the cassette lifter 115, and the lower end of the reaction tube 203 is opened. Subsequently, the processed wafer 200 is carried out from the lower end of the reaction tube 203 to the outside of the reaction tube 203 while being supported by the pod 217 (pod unloading). The processed wafer 200 is then taken out of the pod 217 (wafer release).

(3) Effects according to the present embodiment

According to this embodiment, one or more of the following effects can be obtained.

(a) In this embodiment, SiCl is supplied in 1 cycle₄Step a of gas and supply of Si₂Cl₆Since both steps of the gas step b are performed, the effects of improving the step coverage property of the SiN film formed on the wafer 200 and the uniformity of the film thickness in the wafer surface and the effect of improving the film formation rate of the film can be achieved at the same time.

This is because if the wafer 200 is supplied with Si under the above-mentioned process conditions₂Cl₆SiCl with high gas thermal decomposition temperature and difficult thermal decomposition₄The gas, in turn, forms a substantially uniform thickness Si-containing layer (first layer) of less than 1 atomic layer thickness on the wafer 200. Suppose that step b is not performed but will be performed in sequenceSupplying SiCl₄Step a of gas and supply of NH₃When the cycle of the gas step c is performed a predetermined number of times, the thickness of the Si-containing layer formed in each 1 cycle is uniform over the entire wafer surface, and thus the step coverage property of the SiN film finally formed on the wafer 200 and the uniformity of the film thickness in the wafer surface can be improved. However, since the Si-containing layer formed in each 1 cycle is thin, it may be difficult to increase the film formation rate of the SiN film formed on the wafer 200.

On the other hand, if the wafer 200 is supplied with SiCl under the above-mentioned process conditions₄Si with low gas thermal decomposition temperature and easy thermal decomposition₂Cl₆The gas, a Si-containing layer (second layer) having Si — Si bonds and a thickness of more than 1 atomic layer can be formed on the wafer 200. Assuming that the supply of Si is to be performed in order without performing step a₂Cl₆Step b of gas and supply of NH₃When the cycle of the gas step c is performed a predetermined number of times, the Si-containing layer formed in each 1 cycle is thick, and therefore the film formation rate of the SiN film finally formed on the wafer 200 can be improved. However, since the thickness of the Si-containing layer formed every 1 cycle is likely to be uneven in the wafer surface, it may be difficult to improve the step coverage property of the SiN film formed on the wafer 200 and the uniformity of the film thickness in the wafer surface.

In this embodiment, since two steps of step a and step b are performed, the respective effects obtained by the respective steps can be simultaneously achieved. For example, by terminating step a before saturation of the adsorption reaction of Si and then performing step b having a relatively large film formation rate, the film formation rate can be increased as compared with the case where only step a is performed at the same time. Further, by forming the first layer having relatively excellent thickness uniformity in step a and then forming the second layer based on the first layer in step b, the step coverage property of the SiN film formed on the wafer 200 and the in-wafer-surface film thickness uniformity can be improved as compared with the case of performing only step b.

(b) In this embodiment, step a is performed before step b in each cycle, and then step b is performed, whereby the step coverage property of the SiN film finally formed on the wafer 200 and the uniformity of the film thickness in the wafer surface can be sufficiently exhibited, and the film formation rate can be improved.

If step b is performed before step a in each cycle and then step a is performed, Si containing Si — Si bonds generated by thermal decomposition in step b tends to be irregularly adsorbed on the surface of the wafer 200, and a layer whose thickness tends to be uneven in the wafer surface may be formed as a base of the Si-containing film to be formed in step a. Therefore, the technical significance of step a of forming a substantially uniform thickness Si-containing layer during the film formation process is easily lost.

In contrast, in this embodiment, since step a is performed before step b and then step b is performed in each cycle, a Si-containing layer having a substantially uniform thickness can be formed as a base of the Si-containing film to be formed in step b. Therefore, the technical significance of step a of forming a substantially uniform thickness Si-containing layer in the middle of the film formation process can be fully exerted.

(c) In this embodiment, the composition ratio of Si and N in the SiN film finally formed on the wafer 200 can be controlled widely.

This is because of the reduction of Si per 1 cycle₂Cl₆The amount of gas supplied to the substrate B per 1 cycle of SiCl₄The ratio B/A of the supply amount A of the gas to the substrate can reduce the ratio of Si-Si bonds contained in the second layer, and the thickness of the second layer can be controlled toward the thinning tendency. By making the second layer, i.e., the layer to be nitrided in step c thinner, the composition ratio of the SiN film finally formed on the wafer 200 can be controlled toward a tendency toward a smaller Si composition ratio. For example, by reducing the ratio B/a, the thickness of the second layer can be thinned within a range exceeding the thickness of 1 atomic layer. Thus, the composition ratio of Si can be controlled to be close to smaller than the composition ratio in the stoichiometric composition of the SiN film (i.e., Si: N: 3: 4).

Further, by increasing the B/a, the ratio of Si — Si bonds contained in the second layer can be increased, and the thickness of the second layer can be controlled toward the tendency of thickening. By increasing the thickness of the second layer, i.e., the layer to be nitrided in step c, the composition ratio of the SiN film finally formed on the wafer 200 can be controlled toward a tendency toward an increase in the composition ratio of Si. For example, by increasing the ratio B/a, the thickness of the second layer can be made thicker in a range exceeding the thickness of 1 atomic layer. Thus, the composition ratio of Si can be controlled with a more increased tendency (i.e., Si is enriched) relative to the composition ratio in the stoichiometric composition of the SiN film.

The above B/A can be obtained by, for example, adjusting Si in 1 cycle per time₂Cl₆Time T for gas supply_BRelative to SiCl in each 1 cycle₄Time T for gas supply_ARatio T of_B/T_AI.e. SiCl in each 1 cycle₄Gas and Si₂Cl₆The supply time of the gas is controlled. Further, the above B/A ratio may be adjusted by adjusting Si₂Cl₆Supply flow rate F of gas_BRelative to SiCl₄Supply flow rate F of gas_ARatio F of_B/F_AIs controlled by the size of the sensor.

Furthermore, by adjusting the pressure P in the processing chamber 201 in step b_BSize of (3), control of Si₂Cl₆The thermal decomposition rate of the gas can also be controlled by the composition ratio, which is the ratio of the Si content to the N content in the SiN film finally formed on the wafer 200.

For example by reducing the pressure P_BThe thickness of the second layer can be controlled towards a tendency to be thinner. By making the second layer, i.e., the layer to be nitrided in step c thinner, the composition ratio of the SiN film finally formed on the wafer 200 can be controlled toward a tendency toward a decrease in the composition ratio of Si.

Furthermore, by applying a pressure P_BIs lower than the pressure P in the processing chamber 201 in step a_ALarge, the thickness of the second layer can be controlled towards a tendency to thicken. By increasing the thickness of the second layer, i.e., the layer to be nitrided in step c, the composition ratio of the SiN film finally formed on the wafer 200 can be controlled toward an increase in the composition ratio of Si.

(d) In this embodiment, the treatment temperature in step a is set to be lower than that of SiCl₄The thermal decomposition temperature (first temperature) of the gas is lower so that the treatment temperature in step b is lower than that of Si₂Cl₆Thermal decomposition temperature of gas (second temperature)High degree) and thus the above-described effects can be reliably obtained.

This is because, in step a, since the process temperature is set to a lower temperature than the first temperature, SiCl can be suppressed₄The thermal decomposition of the gas can improve the step coverage property of the SiN film finally formed on the wafer 200 and the uniformity of the film thickness in the wafer surface. Further, the composition ratio of the SiN film can be controlled to be close to Si₃N₄The trend of (c).

In addition, in step b, since the treatment temperature is higher than the second temperature, Si can be maintained₂Cl₆The thermal decomposition of the gas can improve the film formation rate of the SiN film finally formed on the wafer 200. Further, the composition ratio of the SiN film can be controlled to a tendency of Si enrichment.

(e) It is noted that SiCl is used₄When the first source gas other than the gas is used, Si is used₂Cl₆In the case of the second source gas other than the gas, NH is used₃In the case of a reactive gas other than a gas, N is used₂The same effect can be obtained also in the case of an inert gas other than a gas.

< other means >

The embodiments of the present disclosure have been specifically described above. However, the present disclosure is not limited to the above embodiment, and various modifications can be made without departing from the scope of the present disclosure.

In the above embodiment, N is taken as an example of the second element, and NH is taken as the reaction gas containing the second element₃The gas is illustrated as an example, but the disclosure is not limited thereto. For example, oxygen (O) may be used as the second element, and O may be used as the reaction gas containing the second element₂In addition to gases, ozone (O) may also be used₃) Gas, water vapor (H)₂O gas), O₂+H₂Gas, Nitric Oxide (NO) gas, nitric oxide (N)₂O) gas, nitrogen dioxide (NO)₂) Gases, and the like. Further, as the reaction gas, these O-containing gases and the above-mentioned NH may be used₃Both sides of the gas.

For example, a silicon oxide film (SiO film) may be formed on the wafer 200 by the following film formation procedure.

Further, for example, a silicon oxynitride film (SiON film) can be formed on the wafer 200 by the following film formation procedure.

The processing procedure and the processing conditions in each step of the film formation sequence may be, for example, the same processing procedures and processing conditions as those described above. In such a case, the same effects as those of the above-described embodiment can be obtained.

In the above embodiment, for example, SiCl is suspended in step a in an example in which the execution period a of step a and the execution period b of step b do not overlap each other₄After the gas supply, an example in which step b is started after the execution period a is ended is described (see fig. 5). The present disclosure is not limited thereto, and for example, the continuous supply of SiCl may be maintained in step a₄Starting step b in a gaseous state, supplying Si₂Cl₆The gas is a mixture of a gas and a water,thereby, the execution period a of step a and the execution period b of step b are overlapped with each other at least partially (see fig. 6). In addition to the above-described effects, the cycle time can be shortened, and the throughput (throughput) of substrate processing can be improved.

Further, the above-described modes and the like may be used in appropriate combinations. The processing procedure and the processing conditions in this case may be the same as those in the above-described manner, for example.

Examples

As samples 1 to 5, a SiN film was formed on a wafer by using the substrate processing apparatus shown in FIG. 1.

Sample 1 was produced by performing a cycle of sequentially performing step a and step c n times without performing step b. Samples 2 to 5 were produced by repeating the steps a to c in this order n times.

In samples 1-5, SiCl in step a₄The gas supply time was 60 seconds each. In addition, in samples 2-5, Si in step b₂Cl₆The gas supply time was 1.5 seconds, 4.5 seconds, 9 seconds, and 18 seconds, respectively. The other processing conditions include the number of cycles performed and the amount of gas supplied, and are common conditions within the processing condition range in the above embodiment.

Next, the average thickness of the SiN film in the wafer surface of each of samples 1 to 5 was measuredRefractive Index (RI) for light of wavelength 633 nm. These results are shown in FIG. 8.

As is clear from FIG. 8, the average thickness of the SiN films in samples 2 to 5 is larger than that of the SiN film in sample 1. That is, SiCl is supplied as a raw material gas₄Gas and Si₂Cl₆In the case of both gases, Si is not supplied as a source gas₂Cl₆Gas is supplied only to SiCl₄The SiN film formation amount per 1 cycle is increased, that is, the film formation rate is increased, as compared with the gas case.

Further, as can be seen from FIG. 8, Si₂Cl₆Of gasesThe longer the supply time, the thicker the average thickness of the SiN film in the wafer surface in samples 2 to 5. Thus, Si is known₂Cl₆The longer the gas supply time is, the more the deposition amount of the SiN film per 1 cycle increases, that is, the deposition rate of the SiN film formed on the wafer 200 increases.

Further, as is clear from FIG. 8, the refractive index of the SiN films in samples 2 to 5 is larger than that of the SiN film in sample 1. That is, SiCl is supplied as a raw material gas₄Gas and Si₂Cl₆In the case of both gases, Si is not supplied as a source gas₂Cl₆Gas is supplied only to SiCl₄The refractive index of the SiN film increases compared to that of a gas. If the refractive index of Si is 3.882 for light with a wavelength of 633nm, SiCl is supplied as a raw material gas₄Gas and Si₂Cl₆When both gases are gaseous, Si is not supplied₂Cl₆Gas is supplied only to SiCl₄The SiN film formed on the wafer 200 has a larger Si composition ratio than that in the case of gas.

Further, it is known that Si₂Cl₆The longer the gas supply time, the larger the refractive index of the SiN film in samples 2 to 5. Namely, Si is known₂Cl₆The longer the gas supply time is, the larger the Si composition ratio of the SiN film formed on the wafer 200 is.

In addition, as samples 6 and 7, a SiN film was formed on the wafer by using the substrate processing apparatus shown in fig. 1.

Samples 6 and 7 were produced by subjecting a wafer having a trench structure with a trench width of about 50nm, a trench depth of about 10 μm, and an aspect ratio of about 200 on the surface to the following processes.

Sample 6 was produced by performing a cycle of sequentially performing step b and step c n times without performing step a. Sample 7 was produced by performing n cycles of sequentially performing steps a to c.

Specifically, SiCl in step a in sample 7₄The gas supply time was 60 seconds. Si in step b in samples 6 and 7₂Cl₆The gas supply time was 9 seconds each. Other process conditions include the implementation of cyclesThe number of times and the amount of gas supplied are set to common conditions within the processing condition range in the above embodiment.

Then, the Top/Bottom (Top/Bottom) ratio (%) and the interval (Range) (%) in the SiN films of samples 6, 7, respectively, were measured. These results are shown in fig. 9. The "top/bottom ratio (%)" is a ratio of a film thickness formed in an upper portion of a groove of a trench structure to a film thickness formed in a lower portion of the groove of the trench structure, expressed in percentage. When the film thicknesses formed on the upper and lower portions of the groove of the trench structure were represented by C, D, the top/bottom ratio (%) was calculated from the formula of C/D × 100. "section (%)" represents the percentage of the difference between the film thickness value formed in the upper portion of the groove and the film thickness value formed in the lower portion of the groove relative to the average value of the film thickness values formed in the upper portion of the groove and the lower portion of the groove of the trench structure. When the film thicknesses formed on the upper and lower portions of the groove of the trench structure are represented by C, D, the interval (%) is calculated from a formula of | C-D |/[ (C + D)/2] × 100.

As can be seen from fig. 9, the top/bottom ratio in sample 7 is greater than the top/bottom ratio in sample 6. It can also be seen that the interval in sample 7 is smaller than the interval in sample 6. Namely, it is known that SiCl is supplied₄Gas and Si₂Cl₆When both gases are not supplied SiCl₄Gas to supply only Si₂Cl₆The step coverage property and the uniformity of film thickness in the wafer surface are superior to those in the case of gas.

Description of the symbols

200 … wafers, 202 … processing furnace, 217 … wafer box, 115 … wafer box lifter, 121 … controller, 201 … processing chamber, 249a,249b … nozzles, 250a,250b … gas supply holes, 232 a-232 d … gas supply pipes.