JP2017157660A - Method for manufacturing semiconductor device, and substrate processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for efficiently removing a silicon layer and a deposit while minimizing an unwanted damage to a substrate in a silicon layer etching process.SOLUTION: A method for manufacturing a semiconductor device comprises the steps of: supplying a first etching gas to a substrate having a silicon layer, a first silicon oxide-containing film formed on one face of the silicon layer and exposed therefrom, and a second silicon oxide-containing film formed on the other face of the silicon layer and exposed therefrom, thereby removing the first silicon oxide-containing film; supplying a second etching gas for selectively removing the silicon layer to the substrate, thereby removing the silicon layer; and removing the second silicon oxide-containing film.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a semiconductor device manufacturing method and a substrate processing apparatus.

  With the miniaturization of large scale integrated circuits (hereinafter referred to as LSIs), patterning technology has also been miniaturized. As a patterning technique, for example, when performing a step of removing (etching) a silicon (Si) layer formed on the substrate for use as a hard mask, the substrate is processed using a gas having a characteristic of etching the Si layer. (For example, refer to Patent Document 1).

International Publication No. 2015/016149

A deposit (polymer) having an etching target film such as SiO as a main component may adhere to the surface of the Si layer used as a hard mask when a film such as silicon oxide (SiO) is etched. However, when the Si layer is removed, the deposit remains only with an etching gas such as iodine heptafluoride (IF ₇ ) gas having etching selectivity with respect to the Si layer. Further, when etching is performed using an etching gas such as hydrogen fluoride (HF) gas, not only this deposit but also other SiO films and silicon nitride (SiN) films formed as patterns are etched. It will cause damage.

  An object of the present invention is to provide a technique capable of efficiently removing the Si layer and deposits while minimizing unnecessary damage to the substrate in the etching process of the Si layer.

According to one aspect of the invention,
A silicon layer; a first silicon oxide-containing film formed and exposed on one surface of the silicon layer; and a second silicon oxide-containing film formed and exposed on the other surface of the silicon layer. Supplying a first etching gas to the substrate to remove the first silicon oxide-containing film;
Supplying a second etching gas for selectively removing the silicon layer to the substrate to remove the silicon layer;
Removing the second silicon oxide-containing film;
A method of manufacturing a semiconductor device having the above is provided.

  ADVANTAGE OF THE INVENTION According to this invention, in the etching process of a silicon layer, the technique which can remove a silicon layer and a deposit efficiently is provided, minimizing the unnecessary damage to a board | substrate.

It is a longitudinal cross-sectional view for demonstrating the structure of the substrate processing apparatus which concerns on one Embodiment of this invention, Comprising: It is a figure which shows the state in the substrate processing position B. FIG. It is a longitudinal cross-sectional view for demonstrating the structure of the substrate processing apparatus which concerns on one Embodiment of this invention, Comprising: It is a figure which shows the state in the conveyance position A. FIG. It is an upper surface sectional view for explaining a substrate processing apparatus concerning one embodiment of the present invention. It is a block diagram for demonstrating the structure of the control part of the substrate processing apparatus which concerns on one Embodiment of this invention. It is an example of a flow for explaining a substrate processing process concerning one embodiment of the present invention. It is a conceptual diagram for demonstrating the substrate processing process which concerns on one Embodiment of this invention. It is a conceptual diagram for demonstrating the substrate processing process which concerns on one Embodiment of this invention.

  Next, a preferred embodiment of the present invention will be described.

  Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings.

(1) Configuration of Substrate Processing Apparatus FIG. 3 is a top sectional view of a single-wafer type substrate processing apparatus (hereinafter simply referred to as a substrate processing apparatus 10) for carrying out a semiconductor device manufacturing method. The transfer device of the cluster type substrate processing apparatus 10 according to the present embodiment is divided into a vacuum side and an atmosphere side. In the substrate processing apparatus 10, a FOUP (Front Opening Unified Pod) 100 is used as a carrier for transporting the substrate 12.

(Vacuum side configuration)
As shown in FIG. 3, the substrate processing apparatus 10 includes a first transfer chamber 103 that can withstand a pressure (negative pressure) less than atmospheric pressure such as a vacuum state. The casing 101 of the first transfer chamber 103 is, for example, a pentagon in plan view, and is formed in a box shape with both upper and lower ends closed.

  In the first transfer chamber 103, a first substrate transfer machine 112 for transferring the substrate 12 is provided.

  Preliminary chambers (load lock chambers) 122 and 123 are connected to the front side walls of the five side walls of the casing 101 through gate valves 126 and 127, respectively. The preliminary chambers 122 and 123 are configured to be able to use both the function of loading the substrate 12 and the function of unloading the substrate 12, and each has a structure capable of withstanding negative pressure.

  Of the five side walls of the casing 101 of the first transfer chamber 103, four side walls located on the rear side (back side) have a first process unit 202a for performing desired processing on the substrate, and a second process unit. 202b, the third process unit 202c, and the fourth process unit 202d are connected adjacently through gate valves 70a, 70b, 70c, and 70d, respectively.

(Composition on the atmosphere side)
A second transfer chamber 121 that can transfer the substrate 12 under atmospheric pressure is connected to the front sides of the preliminary chambers 122 and 123 through gate valves 128 and 129. The second transfer chamber 121 is provided with a second substrate transfer machine 124 for transferring the substrate 12.

  A notch aligning device 106 is provided on the left side of the second transfer chamber 121. The notch aligning device 106 may be an orientation flat aligning device. In addition, a clean unit for supplying clean air is provided in the upper part of the second transfer chamber 121.

  A substrate loading / unloading port 134 for loading / unloading the substrate 12 to / from the second transfer chamber 121 and a pod opener 108 are provided on the front side of the housing 125 of the second transfer chamber 121. A load port (IO stage) 105 is provided on the opposite side of the pod opener 108 across the substrate loading / unloading port 134, that is, on the outside of the housing 125. The pod opener 108 includes a closure capable of opening and closing the cap 100a of the pod 100 and closing the substrate loading / unloading port 134. By opening and closing the cap 100a of the pod 100 placed on the load port 105, the substrate 12 can be taken in and out of the pod 100. The pod 100 is supplied to and discharged from the load port 105 by an in-process transfer device (OHT or the like) (not shown).

  FIG. 1 is a cross-sectional view showing the main part of the first process unit 202a provided in the substrate processing apparatus 10 in a substrate processing position B where substrate processing is performed. FIG. 2 is a schematic cross-sectional view of the substrate processing apparatus, showing a state where the susceptor is lowered and in a transfer position A where a transfer process can be performed. In this embodiment, an example in which substrate processing is performed in the first process unit 202a will be described. However, similar substrate processing can be performed in the second process unit 202b, the third process unit 202c, and the fourth process unit 202d. . In the following description, the first to fourth process units 202a to 202d are simply referred to as process units 202. Similarly, the gate valves 70a to 70d are simply referred to as the gate valve 70.

(Processing container)
The process unit 202 includes a processing container 14 for processing the substrate 12, and the processing container 14 communicates with the first transfer chamber 103 via a gate valve 70.

  The processing container 14 includes a container body 18 having an upper opening and a lid 20 that closes the upper opening of the container body 18, and forms a sealed processing chamber 22 therein. Note that the processing chamber 22 may be formed in a space surrounded by the lid 20 and the susceptor 64.

(Gas introduction part)
The lid 20 is provided with a gas introduction part 26 and a gas supply part 28. The gas introduction unit 26 is provided in the lid 20, is disposed so as to face the substrate 12 in the processing chamber 22, and is provided to supply the processing gas into the processing chamber 22. The gas introduction unit 26 is provided on the gas introduction upstream side, and is provided on the gas introduction plate 30 having a plurality of gas holes, and on the gas introduction downstream side of the gas dispersion plate 30, and has a number of gas holes to shower the gas. And a shower plate 32 dispersed in a shape.

(Gas supply part)
The gas supply unit 28 is connected to a gas introduction port 34 formed substantially at the center of the upper surface of the gas introduction unit 26, and is configured to supply a processing gas into the processing chamber 22 via the gas introduction unit 26.
The gas supply unit 28 includes a gas supply pipe 36 that communicates with the gas introduction port 34, gas supply pipes 38a, 38b, and 38c that are branched upstream of the gas supply pipe 36, and a gas supply pipe 38a that supplies gas. A gas supply pipe 38d branched on the upstream side, valves 40a, 40b, 40c, 40d, and 40e that are on-off valves for opening and closing gas flow paths provided in the gas supply pipes 38a, 38b, 38c, and 38d, and gas flow rate control Mass flow controllers (MFC) 42a, 42b, 42c, and 42d, which are containers, are supplied into the processing chamber 22 with a desired type of gas at a desired gas flow rate and a desired gas ratio.

  That is, the gas supply pipe 38a is provided with a gas supply source 44a, an MFC 42a, a valve 40a, and a valve 40e in order from the gas supply upstream direction. In the gas supply pipe 38b, a gas supply source 44b, an MFC 42b, and a valve 40b are provided in this order from the gas supply upstream direction. In the gas supply pipe 38c, a gas supply source 44c, an MFC 42c, and a valve 40c are provided in this order from the gas supply upstream direction. The gas supply pipe 38d is provided with a gas supply source 44d, an MFC 42d, and a valve 40d in order from the gas supply upstream direction, and is connected to the upstream side of the valve 40e of the gas supply pipe 38a.

From the gas supply pipe 38a, for example, HF gas which is the first etching gas passes through the gas supply source 44a, the MFC 42a, the valve 40a, the valve 40e, the gas supply pipe 36, the gas inlet 34 and the gas inlet 26. It is supplied into the processing chamber 22. Further, from the gas supply pipe 38b, for example, IF ₇ gas as the second etching gas is passed through the gas supply source 44b, the MFC 42b, the valve 40b, the gas supply pipe 36, the gas inlet 34 and the gas inlet 26. It is supplied into the processing chamber 22. From the gas supply pipe 38c, for example, N ₂ gas which is an inert gas and / or a dilution gas passes through the gas supply source 44c, the MFC 42c, the valve 40c, the gas supply pipe 36, the gas inlet 34 and the gas inlet 26. , And supplied into the processing chamber 22. Further, from the gas supply pipe 38d, for example, methanol gas, which is alcohol, passes through the gas supply source 44d, the MFC 42d, the valve 40d, the valve 40e, the gas supply pipe 36, the gas introduction port 34, and the gas introduction unit 26, and the processing chamber. 22 is supplied. The gas supply sources 44a, 44b, 44c, and 44d may be included in the gas supply line (gas supply unit). The N ₂ gas supplied from the gas supply source 44c may be used as an inert gas (purge gas) in a purge process described later, or may be used as a dilution gas for the etching gas.

(Around susceptor)
The container main body 18 is provided with an exhaust port 48, a transport port 60, and a susceptor 64 incorporating a heater 62. The exhaust port 48 is provided in the container main body 18, communicates with an annular path 66 formed in the upper inner periphery of the container main body 18, and is configured to exhaust the inside of the processing chamber 22 through the annular path 66. Further, the transport port 60 is provided on one side below the exhaust port 48 of the container body 18. The unprocessed substrate 12 such as a silicon wafer is carried into the processing chamber 22 from the first transfer chamber 103 via the transfer port 60, and the processed substrate 12 is transferred from the processing chamber 22 to the first transfer chamber 103. It is unloaded through the transfer port 60. Note that a gate valve 70 as an opening / closing valve for isolating the atmosphere between the first transfer chamber 103 and the processing chamber 22 is provided at the transfer port 60 of the container body 18 so as to be freely opened and closed.

(Susceptor)
A susceptor 64 is provided in the processing chamber 22 of the processing container 14 so as to be movable up and down, and the substrate 12 is held on the surface of the susceptor 64. The substrate 12 is heated by a heater 62 via a susceptor 64.

  A plurality of support pins 74 are erected on the inner bottom portion of the container body 18, and these support pins 74 can penetrate the heater 62 and the susceptor 64, and appear and disappear from the surface of the susceptor 64 as the susceptor 64 moves up and down. It is configured to be free.

  When the process unit 202 is at a position where the susceptor 64 can be lowered to perform a transfer process (FIG. 2, this position is hereinafter referred to as a transfer position A), a plurality of support pins 74 protrude from the susceptor 64 and The substrate 12 can be supported on the support pins 74, and the substrate 12 can be transported and unloaded through the transport port 60 between the processing chamber 22 and the first transport chamber 103. Further, when the process unit 202 is at a position where the susceptor 64 is raised and a processing step can be performed via an intermediate position above the transfer position A (FIG. 1), this position is hereinafter referred to as a substrate processing position B. ), The support pins 74 are not involved, and the substrate 12 is configured to be placed on the susceptor 64.

  The susceptor 64 is provided such that its support shaft 76 is connected to an up-and-down rotation mechanism 77 to move up and down in the processing chamber 22. A bellows (not shown) for sealing the linear motion of the support shaft 76 is provided on the outer periphery of the support shaft 76. The up-and-down rotation mechanism 77 has a multi-stage position of the susceptor 64 in the processing chamber 22 in the vertical direction (transport position A, substrate processing position B, etc.) in each process such as a substrate loading process, a substrate processing process, and a substrate unloading process. It is configured to be adjustable.

  Further, the susceptor 64 is rotatable. That is, the above-described cylindrical support shaft 76 can be rotated by the up-and-down rotation mechanism 77, the susceptor 64 having the heater 62 built in is rotatably provided around the support shaft 76, and the susceptor 64 can be arbitrarily set while holding the substrate 12. It can be rotated at a speed of. On the other hand, the heater 62 provided in the susceptor 64 is fixed and supported by a fixing portion (not shown) inserted through a cylindrical support shaft 76. Thus, by making the susceptor 64 rotatable and fixing the heater 62, the susceptor 64 is rotated relative to the heater 62.

(Exhaust part)
The process unit 202 includes an exhaust unit 46 that exhausts the atmosphere in the processing chamber 22. The exhaust unit 46 adjusts the pressure in the processing chamber 22, an annular path 66 provided in the exhaust path in the processing chamber 22, an exhaust pipe 50 connected to the exhaust port 48, an air valve 54 that opens and closes the exhaust pipe. A pressure regulator (APC) 56 and a vacuum pump 58 are provided, and the atmosphere in the processing chamber 22 is exhausted through the exhaust port 48. The exhaust pipe 50 is provided with a pressure sensor 52 to monitor the pressure in the processing chamber 22. Based on the pressure value acquired by the pressure sensor 52, the pressure in the processing chamber 22 is controlled by controlling the MFC 42a, 42b, 42c, 42d, the air valve 54, the APC 56, etc., and adjusting the gas supply amount and the exhaust amount. Is controlled to a desired value.

(Control part)
A controller 500 serving as a control unit (control unit) controls each of the above-described units so as to perform a substrate processing process described later.
As shown in FIG. 4, the controller 500 is configured as a computer including a CPU (Central Processing Unit) 500a, a RAM (Random Access Memory) 500b, a storage device 500c, and an I / O port 500d. The RAM 500b, the storage device 500c, and the I / O port 500d are configured to exchange data with the CPU 500a via the internal bus 500e. For example, an input / output device 501 configured as a touch panel or a display device 472 such as a display is connected to the controller 500.

  The storage device 500c includes, for example, a flash memory, an HDD (Hard Disk Drive), and the like. In the storage device 500c, a control program that controls the operation of the substrate processing apparatus, a process recipe that describes the procedure and conditions of the substrate processing described later, and the like are stored in a readable manner. Note that the process recipe is a combination of functions so that a predetermined result can be obtained by causing the controller 500 to execute each procedure in a substrate processing step to be described later, and functions as a program. Hereinafter, the process recipe, the control program, and the like are collectively referred to as simply a program. When the term “program” is used in this specification, it may include only a process recipe alone, may include only a control program alone, or may include both. The RAM 500b is configured as a memory area (work area) in which programs, data, and the like read by the CPU 500a are temporarily stored.

  The I / O port 500d includes the heater 62, the MFCs 42a, 42b, 42c, 42d, the valves 40a, 40b, 40c, 40d, 40e, 54, the APC 56, the vacuum pump 58, the gate valve 70, the lifting / lowering rotation mechanism 77, the first. It is connected to the substrate transfer machine 112 and the like.

  The CPU 500a is configured to read and execute a control program from the storage device 500c, and to read a process recipe from the storage device 500c in response to an operation command input from the input / output device 501 or the like. Then, the CPU 500a performs heating / cooling operation of the substrate 12 by the heater 62, pressure adjustment operation by the APC 56, MFCs 42a, 42b, 42c, 42d and valves 40a, 40b, 40c, 40d, so as to follow the contents of the read process recipe. 40e and 54 are configured to control the flow rate adjustment operation of the processing gas, the vertical rotation operation of the susceptor 64 by the up-and-down rotation mechanism 77, and the like.

  Note that the controller 500 is not limited to being configured as a dedicated computer, and may be configured as a general-purpose computer. For example, an external storage device (for example, a magnetic tape, a magnetic disk such as a flexible disk or a hard disk, an optical disk such as a CD or a DVD, a magneto-optical disk such as an MO, a USB memory (USB Flash Drive) or a memory card storing the above-described program. The controller 500 according to the present embodiment can be configured by preparing a semiconductor memory) 123 and installing a program in a general-purpose computer using the external storage device 123. The means for supplying the program to the computer is not limited to supplying the program via the external storage device 123. For example, the program may be supplied without using the external storage device 123 by using communication means such as the Internet or a dedicated line. Note that the storage device 500c and the external storage device 123 are configured as computer-readable recording media. Hereinafter, these are collectively referred to simply as a recording medium. Note that when the term “recording medium” is used in this specification, it may include only the storage device 500c alone, may include only the external storage device 123 alone, or may include both.

(2) Substrate Processing Step Next, a substrate processing step performed as one step of the semiconductor manufacturing process according to the present embodiment will be described with reference to FIGS. FIG. 5 is a flowchart showing a substrate processing process according to this embodiment. FIG. 6 shows the pressure value in the processing chamber 22, the supply amount of HF gas as the first etching gas, the supply amount of alcohol, and the IF ₇ gas as the second etching gas in the substrate processing step according to this embodiment. It is a conceptual diagram which shows the log | history of supply_amount | feed_rate, the supply amount of dilution or an inert gas, and the temperature history of a susceptor. FIG. 7 is a conceptual diagram for explaining a substrate processing process according to an embodiment of the present invention. Such a process is performed by the substrate processing apparatus 10 described above. In this step, the temperature of the susceptor 64 is kept constant. In the following description, the operation of each part constituting the substrate processing apparatus 10 is controlled by the controller 500.

The substrate processing step according to the present embodiment is performed to remove the Si layer used as a mask after etching the SiO layer using the Si layer as a hard mask.
In the pre-etching process performed before the substrate processing process, a Si layer as a hard mask is formed on the SiO layer, and the SiO layer is etched by an etching gas such as HF gas. The Si layer used as a hard mask has a trench-like or columnar structure, the height of the Si layer is, for example, 1000 nm or more, and the aspect ratio of the Si layer after etching the SiO layer is, for example, 50: 1 or more. After this pre-etching step, a natural oxide film as a first silicon oxide-containing film is formed on the upper surface of the Si layer, and a second silicon oxide-containing film is formed on the side surface (side wall) of the Si layer. A deposit (polymer) having SiO as a main component adheres. This deposit adheres at the time of etching the SiO film, and contains the component contained in the etching gas in addition to the main component of the SiO to be etched.
In the substrate processing step according to the present embodiment, in addition to the Si layer used as a hard mask, a natural oxide film formed on the surface of the Si layer and a polymer that is a deposit mainly composed of SiO are removed. It is.
Note that when the substrate processing step according to the present embodiment is started, the surface of the Si layer is covered with a natural oxide film and deposits, and thus is not substantially exposed on the surface of the substrate.
Further, the deposit mainly composed of SiO has a crystal structure.

(Substrate carrying-in process S10)
First, as shown in FIG. 2, the substrate 12 having the Si layer is transferred from the first transfer chamber 103 into the processing chamber 22 through the transfer port 60 by the substrate transfer robot (first substrate transfer machine 112). Is done. The substrate 12 carried into the processing chamber 22 is placed on the support pins 74. At this time, while the atmosphere in the processing chamber 22 is exhausted from the exhaust unit 46, the carry-in path of the substrate 12 is purged with an inert gas (for example, N ₂ gas) under reduced pressure.

(Purge / Heating Step S20)
Next, after the gate valve 70 is closed, the susceptor 64 is raised to the substrate processing position B shown in FIG. 1 by the action of the lifting / lowering rotation mechanism 77, and the substrate 12 is placed on the susceptor 64. At this time, the inside of the processing chamber 22 is purged with an inert gas, the atmospheric gas in the processing chamber 22 is exhausted, and unnecessary moisture or the like that has entered the processing chamber 22 when the substrate 12 is loaded is exhausted. The If necessary, it may be once evacuated to the ultimate vacuum. The heater 62 included in the susceptor 64 is set to a predetermined temperature in advance, and heats the substrate 12 to a predetermined temperature within a range of about 0 ° C to 100 ° C. Further, a cooling mechanism for exhausting excess heat may be used in combination. The temperature of the predetermined substrate may be less than room temperature. In this case, the substrate 12 is cooled by the susceptor 64. When the substrate 12 is cooled, attention should be paid to the substrate temperature and the dew point of the atmosphere so that condensation does not occur at the time of unloading.

(Natural oxide film removal step S30)
When the substrate 12 reaches a predetermined temperature, as shown in FIG. 7A, a process of removing the natural oxide film formed on the Si layer is performed. At this time, the Si layer is not exposed, and a natural oxide film is formed on the upper surface. In this step, the HF gas is supplied into the processing chamber 22 as shown in FIG. 7 (b) under the condition that only the natural oxide film is targeted without removing the deposit mainly composed of SiO. The processing chamber pressure P _{1 at} this time is 10 to 1000 Pa, for example, 500 Pa in this embodiment, and the HF gas supply amount X ₁ supplied from the gas supply pipe 38a is 50 to 500 sccm, for example, 50 sccm in this embodiment. Yes, the supply time of HF gas is, for example, 10 to 180 seconds, and in this embodiment 60 seconds. Further, the HF gas supply amount X _{1 at} this time is smaller than the HF gas supply amount X ₂ in the deposit removal step S50 containing SiO as a main component, which will be described later, the supply time is also short, and the processing chamber pressure P ₁ is S50. It is desirable that the pressure is lower than the processing chamber pressure P _{3 at} . As a result, the natural oxide film can be removed while suppressing damage to the pattern including at least one of the SiO layer or the SiN layer different from the natural oxide film or the deposit containing SiO as a main component. The natural oxide film is thinner than deposits containing SiO as a main component, and other portions of the SiO layer, SiN layer, etc. in the pattern. In general, the deposit has a property that it is less likely to be etched by HF gas than a natural oxide film. That is, the etching rate for the natural oxide film is higher than that for the deposit. This is presumed to be because the deposit also contains components contained in the etching gas used in the pre-etching step. Therefore, by adjusting the supply amount of gas supplied into the processing chamber 22, the processing time, etc., it is possible to remove it under conditions targeting only the natural oxide film.

  The deposit containing SiO as the main component is thicker than the natural oxide film and generally has a property that it is harder to remove than the natural oxide film. However, at least a portion of the deposit remains without being removed, but may be etched at the same time as the removal of the natural oxide film or may undergo surface modification. The progress of etching and surface modification of the deposit in this step promotes the removal in the step S50 of removing the deposit mainly composed of SiO, which will be described later, and has a favorable influence on the processing.

  In this step, alcohol such as methanol may be added to the HF gas at an appropriate mixing ratio. By adding alcohol, the etching rate for SiO is increased, and by removing as much as possible the deposits mainly composed of SiO in this step, the etching time in the subsequent steps can be shortened.

Further, in this step, even if the natural oxide film cannot be completely removed, it is sufficient if it can be removed so that at least a part of the Si layer is exposed. In the Si layer removing step S40 described later, the etching gas reaches the Si layer, It is sufficient that the removal is performed to such an extent that the reaction is possible. However, it is desirable to remove the natural oxide film as much as possible in order to increase the exposed area of the Si layer. Moreover, in this process, you may introduce | transduce dilution gas and an inert gas as needed.
At the end of this process, the atmosphere in the processing chamber 22 is once exhausted.

(Si layer removal step S40)
In this step, as shown in FIG. 7C, the Si layer is completely removed (etched) from the Si layer. Specifically, the Si layer is removed by supplying IF ₇ gas, which is a Si etching gas, into the processing chamber 22 and maintaining a predetermined substrate temperature, gas flow rate, and pressure for a predetermined time. The processing chamber pressure P _{2 at} this time is, for example, 10 to 1000 Pa, 500 Pa in this embodiment, and the IF ₇ gas supply amount Z ₁ supplied from the gas supply pipe 38b is, for example, 100 to 1000 sccm, and 200 sccm in this embodiment. The supply time of IF ₇ gas is, for example, 10 to 180 seconds, and in this embodiment, 60 seconds. IF ₇ gas has high selectivity for Si and is selectively removed. Here, “selective” means that the etching rate for the Si layer is higher than the etching rate for other types of layers. For example, the ratio of the etching rate of the Si layer to the etching rate of the SiO layer, the SiN layer, and the TiN layer by IF ₇ gas is 1E + 5 (= 1 × 10 ⁵ ), 1E + 5 (= 1 × 10 ⁵ ), 1E + 3 (= 1 × 10 ³ ). That is, the IF ₇ gas has a higher etching rate for Si than for SiO. As a result, since the Si layer is selectively removed, only the deposit mainly composed of SiO adhering to the side surface of the Si layer remains. That is, as shown in FIG. 7C, the surface of the deposit that was not exposed by contact with the Si layer before this step is exposed by removing the Si layer. As a result, the exposed area per volume of deposits mainly composed of SiO increases, so that in the subsequent removal step S50 of deposits mainly composed of SiO, the processing time is shortened and the gas supply amount is decreased. The deposits can be efficiently removed while keeping the pressure small.
Also in this step, a dilution gas or an inert gas may be supplied as necessary.
At the end of this process, the atmosphere in the processing chamber 22 is once exhausted.

(Deposit removal step S50 containing SiO as a main component)
In this step, as shown in FIG. 7 (d), an alcohol such as methanol is added to the HF gas and supplied to remove deposits mainly composed of SiO deposited on the side surfaces of the Si layer. . The processing chamber pressure P _{3 at} this time is 10 to 1000 Pa, for example, 500 Pa in this embodiment, and the HF gas supply amount X ₂ supplied from the gas supply pipe 38a is 50 to 500 sccm, for example, 50 sccm in this embodiment. The methanol supply amount Y ₁ supplied from the gas supply pipe 38d is, for example, 250 to 1000 sccm, and in this embodiment, 250 sccm. The supply time of HF gas and methanol is, for example, 10 to 180 seconds, and in this embodiment, 60 seconds. is there. Methanol has excellent selectivity with respect to the structure of other parts in the pattern, and has a relatively high vapor pressure. In the Si layer removal step S40 described above, since the Si layer is removed, the deposit mainly composed of SiO has a large exposed area (surface area), and the deposit per volume exposed to the etching gas. The surface area can be increased. That is, the deposit containing SiO as a main component can be removed from both the inside and the outside, the reaction with the HF gas to which methanol has been added is easier to proceed, the processing time is shortened in this step, and the gas supply amount It is possible to reduce the pressure efficiently and to reduce the pressure efficiently.
As a result, the Si layer and the deposit on the surface thereof are suppressed while suppressing the etching damage to the pattern including at least one of the SiO layer and the SiN layer different from the natural oxide film on the substrate and the deposit mainly composed of SiO. Can be removed. At this time, a dilution gas or an inert gas may be supplied as necessary. Moreover, although the example which added methanol to HF gas was demonstrated in this process, you may make it supply not only this but HF gas.

  As described above, the etching rate for deposits mainly composed of SiO by HF gas is lower than the etching rate for natural oxide films. Accordingly, the natural oxide film having a high etching rate is first removed in the natural oxide film removing step S30, and the deposit having a low etching rate is increased in the deposit removing step S50 mainly composed of SiO. Since all removal is performed with better removal efficiency, in the natural oxide film removal step S30, etching damage to other structures on the substrate 12 can be suppressed. For example, HF gas processing time, supply flow rate, Supply pressure and the like can be kept small.

(Purge / cooling step S60)
Next, the supply of HF gas to which methanol has been added is stopped, and the atmospheric gas in the processing chamber 22 is exhausted. At this time, the gas may be exhausted while supplying, for example, N ₂ gas which is a purge dilution gas or an inert gas. Sufficient purging is performed so that the etching gas does not remain in the treatment chamber 22. Further, the susceptor 64 is lowered to the transfer position A in FIG. 2, the substrate 12 is placed on the support pins 74, separated from the susceptor 64, and cooled to a transferable temperature. If the substrate 12 has been cooled by the susceptor 64 by this step, the substrate temperature will increase in this step. When the substrate temperature is low, pay attention to the substrate temperature at the time of unloading so that condensation does not occur when the substrate is unloaded.

(Substrate unloading step S70)
Next, when the substrate 12 is cooled and ready to be carried out from the inside of the processing chamber 22, it is carried out in the reverse procedure of the above-described substrate carrying-in step S10 while supplying dilution gas or inert gas such as N ₂ gas. To do.

  As described above, the embodiment of the present invention has been specifically described. However, the number of simultaneously processed substrates, the direction in which the substrate is held, the type of dilution gas or purge gas, the type of alcohol added to the HF gas, the substrate processing chamber, The scope of implementation is not limited by the shape of the heating mechanism and the cooling mechanism, and various modifications can be made without departing from the scope of the invention.

  In addition, the first etching gas used in the present invention is not limited to HF gas, and other etching gas may be used. For example, there is a method using an ammonium fluoride aqueous solution, hydrogen plasma, or the like.

  In the above-described embodiment, the deposit mainly composed of SiO attached by etching the SiO film is removed. However, the present invention removes the deposit mainly composed of SiN adhered by etching the SiN film. It is also possible to apply.

Further, the second etching gas used in the present invention is not limited to the IF ₇ gas, and other etching gases may be used. For example, a gas containing a halogen element, particularly a gas containing two or more halogen elements selected from fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) is preferable. For example, iodine pentafluoride (IF ₅ ), iodine heptafluoride (IF ₇ ), bromine trifluoride (BrF ₃ ), bromine pentafluoride (BrF ₅ ), xenon difluoride (XeF ₂ ), trifluoride There is chlorine (ClF ₃ ). More preferably, IF ₇ gas having a characteristic capable of removing the Si layer with high selectivity is used.

Moreover, although the example using methanol as alcohol added to 1st etching gas in this invention was demonstrated, not only this but ethanol, isopropyl alcohol (IPA), etc. can be used. By adding alcohol, HF becomes an anion (HF ₂ ⁻ : bifluoride), and the reactivity with SiO is improved.

  Further, the present invention is not limited to a semiconductor manufacturing apparatus that processes a semiconductor wafer such as the substrate processing apparatus according to the present embodiment, but an LCD (Liquid Crystal Display) manufacturing apparatus that processes a glass substrate, a solar cell manufacturing apparatus, or the like. The present invention can also be applied to an etching process in a substrate processing apparatus and a MEMS (Micro Electro Mechanical Systems) manufacturing apparatus.

(3) Effects according to the present embodiment According to the present embodiment, at least the following effects are provided.

(A) According to this embodiment, in dry etching of the Si layer, deposits (SiO-containing films) mainly composed of SiO deposited on the side surfaces of the Si layer are removed while suppressing damage to other portions of the pattern. can do.

(B) According to the present embodiment, the Si layer can be removed with high selectivity by using IF ₇ gas as the second etching gas.

(C) According to the present embodiment, by using methanol as the alcohol added to the first etching gas, it is possible to perform the processing under the condition where the selectivity with respect to the other part in the pattern is maximized.

(D) According to the present embodiment, by using methanol as the alcohol added to the first etching gas, the vaporization efficiency is increased and simple supply is possible.

DESCRIPTION OF SYMBOLS 10 Substrate processing apparatus 12 Substrate 14 Processing container 18 Container body 22 Processing chamber 26 Gas introduction part 28 Gas supply part 46 Exhaust part 48 Exhaust port 52 Pressure sensor 60 Transport port 64 Susceptor 500 Controller

Claims (3)

A silicon layer; a first silicon oxide-containing film formed and exposed on one surface of the silicon layer; and a second silicon oxide-containing film formed and exposed on the other surface of the silicon layer. Supplying a first etching gas to the substrate to remove the first silicon oxide-containing film;
Supplying a second etching gas for selectively removing the silicon layer to the substrate to remove the silicon layer;
Removing the second silicon oxide-containing film;
A method for manufacturing a semiconductor device comprising:   2. The method of manufacturing a semiconductor device according to claim 1, wherein in the step of removing the second silicon oxide-containing film, a gas containing the first etching gas is supplied. A silicon layer; a first silicon oxide-containing film formed and exposed on one surface of the silicon layer; and a second silicon oxide-containing film formed and exposed on the other surface of the silicon layer. A processing chamber in which substrates are accommodated;
A first gas supply unit for supplying a first etching gas to the processing chamber;
A second gas supply unit for supplying a second etching gas for selectively removing the silicon layer into the processing chamber;
Supplying the first etching gas to the processing chamber to remove the first silicon oxide-containing film; and supplying the second etching gas to the processing chamber to remove the silicon layer. A control unit configured to control the first gas supply unit and the second gas supply unit to perform a step and a step of removing the second silicon oxide-containing film;
A substrate processing apparatus.

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