WO2023153203A1

WO2023153203A1 - Substrate processing method and substrate processing apparatus

Info

Publication number: WO2023153203A1
Application number: PCT/JP2023/002185
Authority: WO
Inventors: 祐希吉田
Original assignee: 東京エレクトロン株式会社
Priority date: 2022-02-08
Filing date: 2023-01-25
Publication date: 2023-08-17
Also published as: TW202422685A; JPWO2023153203A1; KR20240141316A; CN118633144A

Abstract

A substrate processing method according to the present invention comprises a step for preparing a substrate and a step for etching the substrate. In the step for preparing a substrate, a substrate which has a multilayer film that comprises a plurality of silicon oxide films having different film thicknesses is prepared. In the step for etching the substrate, the substrate is etched with an etching liquid to which hydrochloric acid is added.

Description

Substrate processing method and substrate processing apparatus

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

Conventionally, there is known a technique of etching a silicon oxide film formed on a substrate such as a semiconductor wafer with an etchant containing, for example, hydrofluoric acid (see Patent Document 1).

JP-A-8-31794

The present disclosure provides a technique for etching a laminated film including a plurality of silicon oxide films with different film thicknesses, which can reduce variations in etching rate for each silicon oxide film.

A substrate processing method according to one aspect of the present disclosure includes a step of preparing a substrate and a step of etching the substrate. The step of preparing a substrate prepares a substrate having a laminated film including a plurality of silicon oxide films with different film thicknesses. In the step of etching the substrate, the substrate is etched with an etchant to which hydrochloric acid is added.

According to the present disclosure, in a technique for etching a laminated film including a plurality of silicon oxide films with different film thicknesses, it is possible to reduce variations in etching rate for each silicon oxide film.

FIG. 1 is an explanatory diagram of substrate processing according to the embodiment. FIG. 2 is an explanatory diagram of substrate processing according to the embodiment. FIG. 3 is a graph showing variations in etching rate for each silicon oxide film when using an etchant to which hydrochloric acid and a metal salt are added. FIG. 4 is a graph showing variations in etching rate for each silicon oxide film when using an etchant to which hydrochloric acid and a metal salt are added. FIG. 5 is a diagram for explaining the formation of water clusters. FIG. 6 is a diagram for explaining the formation of spherical structures. FIG. 7 is a diagram for explaining how the surface potential of a portion of the polysilicon film shifts from negative to positive. FIG. 8 is a graph showing variations in etching rate for each silicon oxide film when using an etchant containing a surfactant. FIG. 9 is a graph showing variations in etching rate for each silicon oxide film when using an etchant containing a surfactant. FIG. 10 is a diagram showing the configuration of the substrate processing apparatus according to the embodiment. FIG. 11 is a diagram showing the configuration of a processing bath according to the embodiment. FIG. 12 is a flow chart showing the procedure of processing executed by the substrate processing apparatus according to the embodiment. FIG. 13 is a diagram illustrating a configuration example of a processing unit according to a modification;

Hereinafter, embodiments for implementing the nozzle, substrate processing method, and substrate processing apparatus according to the present disclosure (hereinafter referred to as "embodiments") will be described in detail with reference to the drawings. Note that the present disclosure is not limited by this embodiment. Further, each embodiment can be appropriately combined within a range that does not contradict the processing contents. Also, in each of the following embodiments, the same parts are denoted by the same reference numerals, and overlapping descriptions are omitted.

Further, in the embodiments described below, expressions such as "constant", "perpendicular", "perpendicular" or "parallel" may be used, but these expressions are strictly "constant", "perpendicular", " It does not have to be "perpendicular" or "parallel". That is, each of the expressions described above allows deviations in, for example, manufacturing accuracy and installation accuracy.

In addition, in each drawing referred to below, in order to make the explanation easier to understand, an orthogonal coordinate system is shown in which the X-axis direction, the Y-axis direction and the Z-axis direction that are orthogonal to each other are defined, and the Z-axis positive direction is the vertically upward direction. Sometimes. Also, the direction of rotation about the vertical axis is sometimes called the θ direction.

<About substrate processing>
First, details of substrate processing according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 and 2 are explanatory diagrams of substrate processing according to the embodiment.

In the substrate processing according to the embodiment, first, a semiconductor wafer (hereinafter referred to as wafer W) having the structure shown in FIG. 1 is prepared. The wafer W is constructed by forming a plurality of silicon oxide films 11 and a plurality of polysilicon films 12 on a silicon substrate 10 .

A plurality of silicon oxide films 11 are formed on the silicon substrate 10 at intervals in the vertical direction. The plurality of silicon oxide films 11 have different film thicknesses. The film thickness of the plurality of silicon oxide films 11 is, for example, 1 nm or more and 30 nm or less.

The polysilicon film 12 is formed adjacent to each of the plurality of silicon oxide films 11 in the vertical direction. Since the plurality of silicon oxide films 11 have different film thicknesses, the polysilicon films 12 in contact with each of the plurality of silicon oxide films 11 are formed with different intervals therebetween.

Thus, the wafer W to be subjected to substrate processing has a laminated film in which the silicon oxide film 11 and the polysilicon film 12 are alternately laminated. Note that the wafer W may be a laminated film including at least a plurality of silicon oxide films 11 having different film thicknesses, and the structure of the laminated film is not particularly limited to the example shown in FIG. For example, as other films formed adjacent to each of the plurality of silicon oxide films 11, in addition to the polysilicon film 12 described above, a silicon film, a silicon nitride film, a metal-containing film, or the like can be used. That is, the other film can be selected from at least one of a silicon film, a polysilicon film, a silicon nitride film and a metal-containing film.

In addition, the wafer W is formed with grooves 15 through which the etchant penetrates to etch the laminated silicon oxide film 11 .

The substrate processing according to the embodiment selectively etches the silicon oxide film 11 by an etching process using an etchant. As a result, as shown in FIG. 2, the end face of the silicon oxide film 11 facing the trench 15 recedes from the end face of the polysilicon film 12 facing the trench 15 in the width direction of the trench 15 , and the polysilicon film 12 is flattened. The upper and lower surfaces of the ends are exposed.

Here, as the difference in film thickness of the silicon oxide films 11 in the laminated film increases, the variation in etching rate for each silicon oxide film 11 increases. Specifically, the silicon oxide film 11 having a smaller thickness is less likely to be etched than the silicon oxide film 11 having a larger thickness.

On the other hand, the inventors of the present application have found that the etching rate of each silicon oxide film 11 is reduced by etching the wafer W using an etching solution to which at least one of hydrochloric acid, a metal salt, and a surfactant is added. It was found that variation can be suppressed. 3 and 4 are graphs showing variations in etching rate for each silicon oxide film 11 when using an etchant containing hydrochloric acid (HCl) and metal salt (NaCl or CaCl ₂ ).

The processing conditions for the experimental results shown in FIGS. 3 and 4 are as follows.
Lamination number of silicon oxide films in laminated film: 3
Thickness of silicon oxide film: 15 nm, 30 nm, 7.5 nm from the bottom layer
Treatment process: immersion in etching solution (etching treatment), then immersion in DIW (deionized water) (rinsing treatment), then drying treatment using dry gas Etching solution: hydrofluoric acid (HF) aqueous solution To etching solution Additives added: Hydrochloric acid (HCl) and metal salts (NaCl or CaCl ₂ )

In FIGS. 3 and 4, the vertical axis represents an etching rate ratio (ER ratio), which is an index value for determining variations in etching rate for each silicon oxide film 11 . The etching rate ratio is the ratio of the etching rate of the silicon oxide film 11 having the smallest thickness to the etching rate of the silicon oxide film 11 having the largest thickness among the plurality of laminated silicon oxide films. The etching rate ratio indicates that the closer the value is to 1, the smaller the variation in the etching rate for each silicon oxide film 11 is.

Also, in the graphs shown in FIGS. 3 and 4, "w/o Additives" indicates the etching rate ratio in the laminated film when using an etching solution to which hydrochloric acid and metal salt are not added. "HCl" indicates the etching rate ratio in the laminated film when using an etching solution to which hydrochloric acid (HCl) is added. "NaCl" indicates the etching rate ratio in the laminated film when using an etchant to which NaCl is added as a metal salt. “CaCl ₂ ” indicates the etching rate ratio in the laminated film when using an etchant to which CaCl ₂ is added as a metal salt. FIG. 3 shows experimental results when the concentration of hydrochloric acid and metal salt in the etching solution is 0.05 wt %, and FIG. %.

As shown in FIGS. 3 and 4, the etching rate ratio when using the etching solution to which NaCl is added as a metal salt is higher than the etching rate ratio when using the etching solution to which neither hydrochloric acid nor metal salt is added. big in comparison. Also, as shown in FIG. 4, the etching rate ratio when using an etching solution to which CaCl ₂ is added as a metal salt is higher than the etching rate ratio when using an etching solution to which neither hydrochloric acid nor a metal salt is added. big in comparison. Further, as shown in FIG. 4, the etching rate ratio in the case of using the etching solution to which hydrochloric acid (HCl) is added is compared to the etching rate ratio in the case of using the etching solution to which neither hydrochloric acid nor metal salt is added. big. As described above, from the experimental results shown in FIGS. 3 and 4, by etching the wafer W using the etchant to which NaCl is added as a metal salt, variations in the etching rate for each silicon oxide film 11 can be suppressed. It is understood that Further, from the experimental results shown in FIG. 4, it can be seen that the variation in the etching rate for each silicon oxide film 11 can be suppressed by etching the wafer W using the etchant to which CaCl ₂ is added as a metal salt. . Further, from the experimental results shown in FIG. 4, it can be seen that the variation in the etching rate for each silicon oxide film 11 can be suppressed by etching the wafer W using an etchant to which hydrochloric acid (HCl) is added.

This experimental result is considered, for example, as follows. That is, the etching mechanism of the silicon oxide film 11 proceeds as follows. First, as shown in chemical reaction formula (1), silicon oxide (SiO ₂ ) reacts with hydrofluoric acid (HF) contained in the etchant and dissolves in the etchant. In other words, silicon oxide film 11 is etched.

_SiO2 +6HF-> _H2SiF6 + _2H2O (1 ₎

Further, in the etchant, hydrogen difluoride ions (HF ₂ ⁻ ) are generated by the reactions represented by the chemical reaction formulas (2) and (3).

HF⇔H ⁺ +F ^- (2)
HF+F ^- ⇔ HF ₂ ^- (3)

Hydrogen difluoride ions (HF ₂ ⁻ ) generated by the reactions represented by the chemical reaction formulas (2) and (3) function as an etchant for silicon oxide (SiO ₂ ), and the above chemical reaction formula (1) It further accelerates the indicated reaction.

In this manner, the etching of the silicon oxide film 11 proceeds by promoting the reaction between silicon oxide (SiO ₂ ) and hydrofluoric acid (HF) by the etchant hydrogen difluoride ions (HF ₂ ⁻ ). . Therefore, in order for the etching of the silicon oxide film 11 to progress, it is important that the hydrogen difluoride ions (HF ₂ ⁻ ) reach the silicon oxide film 11 .

As the etching of the silicon oxide film 11 progresses, hydrogen ions (H ⁺ ) increase in the etchant due to the progress of reactions represented by chemical reaction formulas (2) and (3). Hydrogen ions (H ⁺ ) cannot exist stably in the etchant, and combine with water molecules (that is, hydrate) to form oxonium ions (H ₃ O ⁺ ). Oxonium ions (H ₃ O ⁺ ) are attracted to the surface of polysilicon film 12 because polysilicon film 12 in contact with silicon oxide film 11 is negatively charged. Then, as shown in FIG. 5, the oxonium ions (H ₃ O ⁺ ) combine with water molecules (that is, hydrate) on the surface of the polysilicon film 12 to form a plurality of water molecules into a planar shape. to form water clusters 16p arranged in a row. FIG. 5 is a diagram for explaining the formation of water clusters. Water clusters 16p are formed more densely as the distance between polysilicon films 12 in contact with silicon oxide film 11 is narrower, in other words, as the film thickness of silicon oxide film 11 is smaller.

Therefore, if the thickness of the silicon oxide film 11 is small, the water clusters 16p may prevent the hydrogen difluoride ions (HF ₂ ⁻ ) from reaching the silicon oxide film 11 . As a result, the etching rate of the silicon oxide film 11 with a smaller thickness is lower than the etching rate of the silicon oxide film 11 with a larger thickness. As a result, the etching rate of each silicon oxide film 11 varies.

On the other hand, when an etchant to which a metal salt (eg, NaCl) is added is used, metal ions (eg, Na ⁺ ) and anions (eg, Cl ⁻ ) are generated by ionizing the metal salt in the etchant. occur. Anions (for example, Cl ⁻ ) generated from the metal salt in the etchant destroy the hydration structure (that is, bonds between water molecules) in the water clusters 16 p on the surface of the polysilicon film 12 . In addition, metal ions (eg, Na ⁺ ) generated from the metal salt in the etching solution combine with water molecules (that is, hydrate) on the surface of the polysilicon film 12, as shown in FIG. , to form a spherical structure 16s in which a plurality of water molecules are arranged in a spherical shape. FIG. 6 is a diagram for explaining the formation of spherical structures. When the spherical structures 16s are formed on the surface of the polysilicon film 12, even if the thickness of the silicon oxide film 11 is small, the space through which hydrogen difluoride ions (HF ₂ ⁻ ) can pass increases. , the arrival of hydrogen difluoride ions (HF ₂ ⁻ ) to the silicon oxide film 11 is not hindered. As a result, it is considered that the variation in the etching rate for each silicon oxide film 11 is reduced as compared with the case of using an etchant to which no metal salt is added.

Further, when an etching solution to which hydrochloric acid is added is used, the pH of the etching solution becomes more acidic (for example, the pH is less than 1), and as shown in FIG. becomes easier to shift from negative to positive. FIG. 7 is a diagram for explaining how the surface potential of a portion of the polysilicon film shifts from negative to positive. When the surface potential of a portion of polysilicon film 12 shifts from negative to positive, oxonium ions (H ₃ O ⁺ ) are repulsed on the surface of polysilicon film 12, making it difficult for water clusters 16p to form. . Therefore, even if the thickness of the silicon oxide film 11 is small, the space through which the hydrogen difluoride ions (HF ₂ ⁻ ) can pass increases, and the hydrogen difluoride ions (HF ₂ ⁻ ) pass through the silicon oxide film. Reaching 11 is not hindered. As a result, it is considered that the variation in the etching rate for each silicon oxide film 11 is reduced as in the case of using an etchant to which a metal salt is added.

FIGS. 8 and 9 are graphs showing variations in etching rate for each silicon oxide film 11 when using an etchant to which a surfactant (OACl, OTMACl or SDBS) is added.

The processing conditions for the experimental results shown in FIGS. 8 and 9 are the same as the processing conditions for the experimental results shown in FIGS. 3 and 4, except for the following points.
Surfactants added to the etchant: n-octylamine hydrochloride (OACl), n-octyltrimethylammonium chloride (OTMACl) or sodium dodecylbenzenesulfonate (SDBS)

In FIGS. 8 and 9, the vertical axis represents an etching rate ratio (ER ratio), which is an index value for determining variations in etching rate for each silicon oxide film 11 . The etching rate ratio is the ratio of the etching rate of the silicon oxide film 11 having the smallest thickness to the etching rate of the silicon oxide film 11 having the largest thickness among the plurality of laminated silicon oxide films. The etching rate ratio indicates that the closer the value is to 1, the smaller the variation in the etching rate for each silicon oxide film 11 is.

Also, in the graphs shown in FIGS. 8 and 9, "w/o Additives" indicates the etching rate ratio in the laminated film when using an etchant to which no surfactant is added. Further, "OACl" indicates the etching rate ratio in the laminated film when using an etchant to which OACl is added as a surfactant. Also, "OTMACl" indicates the etching rate ratio in the laminated film when using an etchant to which OTMACl is added as a surfactant. "SDBS" indicates the etching rate ratio in the laminated film when using an etchant to which SDBS is added as a surfactant. FIG. 8 shows the experimental results when the surfactant concentration in the etching solution is 0.05 wt %, and FIG. 9 shows the experimental results when the surfactant concentration in the etching solution is 0.5 wt %. This is the result.

As shown in FIGS. 8 and 9, the etching rate ratio in the case of using the etchant to which OTMACl is added as a surfactant is higher than the etching rate ratio in the case of using the etchant to which no surfactant is added. big in comparison. Further, as shown in FIG. 9, the etching rate ratio when using an etching solution to which OACl or SDBS is added as a surfactant is the etching rate ratio when using an etching solution to which no surfactant is added. large compared to As described above, from the experimental results shown in FIGS. 8 and 9, by performing the etching process of the wafer W using the etchant to which OTMACl is added as a surfactant, the variation in the etching rate for each silicon oxide film 11 can be reduced. I know it can be suppressed. Further, from the experimental results shown in FIG. 9, it is found that etching the wafer W using an etchant to which OACl or SDBS is added as a surfactant suppresses variations in the etching rate for each silicon oxide film 11 . I understand.

This experimental result is considered, for example, as follows. That is, when an etchant to which a surfactant is added is used, the surfactant in the etchant forms a hydration structure (that is, between water molecules) in the water clusters 16p (see FIG. 5) on the surface of the polysilicon film 12. bond). When the hydration structure in the water clusters 16p on the surface of the polysilicon film 12 is destroyed, even if the thickness of the silicon oxide film 11 is small, a space through which hydrogen difluoride ions (HF ₂ ⁻ ) can pass. increases, and the arrival of hydrogen difluoride ions (HF ₂ ⁻ ) to the silicon oxide film 11 is not hindered. As a result, it is considered that the variation in the etching rate for each silicon oxide film 11 is reduced as compared with the case of using an etchant to which no surfactant is added.

Therefore, based on the results of FIGS. 3, 4, 8, and 9, in the substrate processing according to the embodiment, an etchant to which at least one of hydrochloric acid, a metal salt, and a surfactant is added is used to oxidize silicon. It was decided to perform an etching process for the film 11 .

The etchant according to the embodiment is a chemical solution containing hydrofluoric acid. The concentration of hydrofluoric acid in the etchant is, for example, 0.1 wt % or more and 50 wt % or less.

As the metal salt added to the etchant, for example, an alkali metal halide or an alkaline earth metal halide can be used. As the alkali metal halide, for example, NaCl mentioned above can be used. Also, the alkali metal halide may contain at least one of Li, Na, K, Rb and Cs. As the alkaline earth metal halide, for example CaCl ₂ as described above can be used. Also, the alkaline earth metal halide may contain at least one of Mg, Ca, Sr and Ba.

Also, the concentration of each of hydrochloric acid and metal salt in the etching solution is preferably 0.5 wt % or more and 5 wt % or less. As is clear from the experimental results shown in FIGS. 3 and 4, this makes it possible to reduce variations in the etching rate for each silicon oxide film 11 regardless of the type of metal salt. Further, by setting the concentration of the metal salt in the etchant to 5 wt % or less, contamination of the wafer W with metal can be suppressed.

Also, the concentration of hydrochloric acid before being added to the etching solution is preferably 35 wt % or more and 37 wt % or less, for example.

As the surfactant added to the etching solution, for example, a cationic surfactant or an anionic surfactant can be used. As a cationic surfactant, for example, n-octylamine hydrochloride (OACl) or n-octyltrimethylammonium chloride (OTMACl) described above can be used. As an anionic surfactant, for example, sodium dodecylbenzenesulfonate (SDBS) described above can be used.

Also, the concentration of the surfactant in the etching liquid is preferably 0.5 wt % or more and 5 wt % or less. As is clear from the experimental results shown in FIGS. 8 and 9, this makes it possible to reduce variations in the etching rate for each silicon oxide film 11 regardless of the type of surfactant. Further, by setting the concentration of the surfactant in the etching liquid to 5 wt % or less, it is possible to suppress the organic matter (dirt) removed by the surfactant from remaining on the surface of the wafer W. FIG.

[Configuration of substrate processing apparatus]
Next, the configuration of the substrate processing apparatus that performs the substrate processing described above will be described with reference to FIG. FIG. 10 is a diagram showing the configuration of the substrate processing apparatus according to the embodiment.

As shown in FIG. 10, the substrate processing apparatus 1 according to the embodiment includes a carrier loading/unloading unit 2, a lot forming unit 3, a lot placement unit 4, a lot transport unit 5, a lot processing unit 6, a control a part 7;

The carrier loading/unloading section 2 includes a carrier stage 20 , a carrier transport mechanism 21 ,

carrier stocks

22 and 23 , and a carrier table 24 .

The carrier stage 20 carries a plurality of carriers 9 transported from the outside. The carrier 9 is a container that accommodates a plurality of (for example, 25) semiconductor wafers (hereinafter referred to as wafers W) arranged vertically in a horizontal posture. The carrier transport mechanism 21 transports the carrier 9 among the carrier stage 20 ,

carrier stocks

22 and 23 and carrier table 24 .

From the carrier 9 mounted on the carrier mounting table 24, a plurality of wafers W to be processed are unloaded to the lot processing section 6 by the substrate transport mechanism 30, which will be described later. A plurality of processed wafers W are carried from the lot processing section 6 to the carrier 9 mounted on the carrier mounting table 24 by the substrate transfer mechanism 30 .

The lot formation unit 3 has a substrate transport mechanism 30 and forms lots. A lot consists of a plurality of (for example, 50) wafers W that are processed simultaneously by combining wafers W housed in one or more carriers 9 . A plurality of wafers W forming one lot are arranged at regular intervals with their plate surfaces facing each other.

The substrate transfer mechanism 30 transfers a plurality of wafers W between the carrier 9 mounted on the carrier mounting table 24 and the lot mounting section 4 .

The lot placing unit 4 has a lot transport table 40 and temporarily places (stands by) the lot transported between the lot forming unit 3 and the lot processing unit 6 by the lot transporting unit 5 . The lot conveyance table 40 includes a loading-side lot mounting table 41 for mounting a lot formed by the lot forming section 3 before being processed, and an unloading-side lot mounting table for mounting a lot processed by the lot processing section 6. 42. A plurality of wafers W for one lot are placed in a standing posture in front and behind on the load-in side lot table 41 and the carry-out side lot table 42 .

The lot transport unit 5 has a lot transport mechanism 50 and transports lots between the lot placement unit 4 and the lot processing unit 6 and inside the lot processing unit 6 . The lot transport mechanism 50 has a rail 51 , a moving body 52 and a substrate holder 53 .

The rails 51 are arranged along the X-axis direction across the lot placement section 4 and the lot processing section 6 . The moving body 52 is configured to be movable along the rails 51 while holding a plurality of wafers W. As shown in FIG. The substrate holder 53 is provided on the moving body 52 and holds a plurality of wafers W arranged in front and back in an upright posture.

The lot processing unit 6 performs etching processing, cleaning processing, drying processing, etc. on a plurality of wafers W for one lot. In the lot processing section 6 , a plurality (here, two) of etching processing devices 60 , substrate holder cleaning processing devices 80 , and drying processing devices 90 are arranged side by side along rails 51 .

The etching processing apparatus 60 collectively performs etching processing on a plurality of wafers W for one lot. The substrate holder cleaning apparatus 80 performs cleaning processing of the substrate holder 53 . The drying processing apparatus 90 collectively performs drying processing on a plurality of wafers W for one lot. The number of etching processing devices 60, substrate holder cleaning processing devices 80, and drying processing devices 90 is not limited to the example in FIG.

The etching processing apparatus 60 includes a processing bath 61 for etching processing, a processing bath 62 for rinsing processing, and

substrate lifting mechanisms

63 and 64 .

The processing bath 61 and the processing bath 62 can accommodate one lot of wafers W, and store an etchant. An etchant is stored in the processing bath 61 . Details of the processing tank 61 will be described later.

A processing liquid (deionized water, etc.) for rinsing is stored in the processing tank 62 . The

substrate elevating mechanisms

63 and 64 hold a plurality of wafers W forming a lot in a state of being arranged back and forth in an upright posture.

The etching processing apparatus 60 holds the lot conveyed by the lot conveying unit 5 by the substrate lifting mechanism 63, immerses the lot in the etching solution in the processing bath 61, and performs etching processing. The etching apparatus 60 holds the lot transported to the processing bath 62 by the lot transport unit 5 by the substrate lifting mechanism 64 and immerses the lot in the rinsing liquid of the processing bath 62 for rinsing.

The drying processing apparatus 90 has a processing bath 91 and a substrate lifting mechanism 92 . A processing gas for drying is supplied to the processing bath 91 . The substrate lifting mechanism 92 holds a plurality of wafers W for one lot side by side in the front-rear direction in an upright posture.

The drying processing device 90 holds the lot transported by the lot transporting unit 5 with the substrate lifting mechanism 92 and performs drying processing using the processing gas for drying processing supplied into the processing bath 91 . The lot that has been dried in the processing tank 91 is transferred to the lot placement section 4 by the lot transfer section 5 .

The substrate holder cleaning processing apparatus 80 supplies cleaning processing liquid to the substrate holder 53 of the lot transport mechanism 50 and further supplies dry gas to perform cleaning processing of the substrate holder 53 .

The control unit 7 controls the operation of each unit of the substrate processing apparatus 1 (carrier loading/unloading unit 2, lot forming unit 3, lot placement unit 4, lot transport unit 5, lot processing unit 6, etc.). The control section 7 controls the operation of each section of the substrate processing apparatus 1 based on signals from switches, various sensors, and the like.

The control unit 7 includes a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), input/output ports, and various circuits, and programs stored in a storage unit (not shown). is read and executed to control the operation of the substrate processing apparatus 1 . The control unit 7 has a computer-readable storage medium 8 . The storage medium 8 stores the above programs for controlling various processes executed in the substrate processing apparatus 1 . The program may have been stored in the computer-readable storage medium 8 and installed in the storage medium 8 of the control unit 7 from another storage medium.

Examples of computer-readable storage media 8 include hard disks (HD), flexible disks (FD), compact disks (CD), magnet optical disks (MO), memory cards, and the like.

[Structure of processing tank]
Next, the configuration of the processing tank 61 used for etching according to the embodiment will be described with reference to FIG. FIG. 11 is a diagram showing the configuration of the processing tank 61 according to the embodiment.

As shown in FIG. 11, the processing tank 61 performs an etching process for etching the silicon oxide film 11 formed on the wafers W by immersing the wafers W for one lot in an etchant.

The processing bath 61 includes an inner bath 100 and an outer bath 110 . The processing tank 61 also includes a circulation section 120 and an etchant supply section 130 .

The inner tank 100 is open at the top and stores an etchant inside. A lot (a plurality of wafers W) is immersed in such an inner bath 100 .

The outer tub 110 is open at the top and is arranged around the top of the inner tub 100 . The etchant overflowing from the inner bath 100 flows into the outer bath 110 .

The circulation unit 120 circulates the etchant between the inner bath 100 and the outer bath 110 . The circulation section 120 includes a circulation path 121 , a nozzle 122 , a pump 123 , a filter 124 and a temperature adjustment section 125 .

The circulation path 121 connects the outer tank 110 and the inner tank 100 . One end of the circulation path 121 is connected to the outer bath 110 and the other end of the circulation path 121 is connected to a nozzle 122 arranged inside the inner bath 100 .

The pump 123 , the filter 124 and the temperature adjustment section 125 are provided in the circulation path 121 . A pump 123 sends out the etchant in the outer bath 110 to the circulation path 121 . Filter 124 removes impurities from the etchant flowing through circulation path 121 . The temperature adjustment unit 125 is, for example, a heater, and adjusts the temperature of the etchant flowing through the circulation path 121 to a temperature suitable for the etching process. Pump 123 and temperature adjuster 125 are controlled by controller 7 .

The circulation unit 120 sends the etchant from the outer tank 110 to the inner tank 100 via the circulation path 121 . The etchant sent into the inner bath 100 overflows the inner bath 100 and flows out to the outer bath 110 again. Thus, the etchant circulates between the inner bath 100 and the outer bath 110 .

The etchant supply unit 130 supplies the etchant to the processing bath 61 . The etchant supply unit 130 includes an etchant supply source 131 , a supply path 132 , a valve 133 and a switching unit 134 .

The etchant supply source 131 supplies an etchant to which at least one of hydrochloric acid, metal salt, and surfactant has been added in advance. The supply path 132 is connected to the etchant supply source 131 and supplies the etchant supplied from the etchant supply source 131 to the inner bath 100 or the outer bath 110 . The valve 133 is provided in the supply path 132 and opens and closes the supply path 132 . The switching unit 134 is provided in the supply path 132 and switches the outflow destination of the etchant flowing through the supply path 132 between the inner tank 100 and the outer tank 110 .

The valve 133 and the switching section 134 are electrically connected to the control section 7 and controlled by the control section 7 . For example, when the etchant is stored in the empty processing bath 61, the control unit 7 controls the valve 133 and the switching unit 134 to supply a new etchant from the etchant supply source 131 to the inner bath 100. supply. Further, when the etching liquid is to be replenished to the processing tank 61, the control section 7 controls the valve 133 and the switching section 134 to supply new etching liquid from the etching liquid supply source 131 to the outer tank 110. supply.

[Specific Operation of Substrate Processing Apparatus]
Next, specific operations of the substrate processing apparatus 1 according to the embodiment will be described with reference to FIG. 12 . FIG. 12 is a flow chart showing the procedure of processing executed by the substrate processing apparatus 1 according to the embodiment. The processing procedure shown in FIG. 12 is executed under the control of the control unit 7 .

As shown in FIG. 12, the substrate processing apparatus 1 first performs a preparation process (step S101). In the preparation process, as shown in FIG. 1, a plurality of wafers W each having a laminated film including a plurality of silicon oxide films 11 with different film thicknesses are prepared.

Subsequently, in the substrate processing apparatus 1, an etching process using an etchant is performed on a plurality of wafers W forming a lot (step S102). In the etching process, the plurality of wafers W are lowered using the substrate lifting mechanism 63 to immerse the plurality of wafers W in the etchant stored in the inner bath 100 of the processing bath 61 .

This etching process is performed until the laminated film formed on the wafer W changes from the initial state shown in FIG. 1 to the laminated surface exposed state shown in FIG. That is, the etching process exposes the lamination surfaces (upper and lower surfaces) of the polysilicon film 12 by etching the silicon oxide film 11 in contact with the polysilicon film 12 .

The inventors of the present application have found that the etching solution to which at least one of hydrochloric acid, a metal salt, and a surfactant are added is more effective than an etching solution to which hydrochloric acid, a metal salt, and a surfactant are not added. It has been confirmed experimentally that the variation in etching rate between each step is reduced. Therefore, in the substrate processing apparatus 1, an etching process is performed using an etchant to which at least one of hydrochloric acid, a metal salt, and a surfactant is added. Thereby, variations in the etching rate for each silicon oxide film 11 can be reduced.

Subsequently, a rinse process is performed in the substrate processing apparatus 1 (step S103). In the rinsing process, a plurality of wafers W that have undergone the etching process are transported to the processing tank 62 for the rinsing process and immersed in a rinse liquid (deionized water or the like) stored in the processing tank 62 . Thereby, the etchant is washed away from the plurality of wafers W. FIG.

Subsequently, a drying process is performed in the substrate processing apparatus 1 (step S104). In the drying process, a plurality of wafers W that have finished the rinsing process are transferred to the processing tank 91 for the drying process, and the rinsing liquid adhering to the surfaces of the plurality of wafers W is removed by the processing gas. Thereby, the plurality of wafers W are dried.

After that, the plurality of wafers W that have undergone the drying process are housed in the carrier 9 placed on the carrier stage 20 . Thus, substrate processing for one lot is completed.

[Variation]
The substrate processing according to the embodiment can also be applied to a single-wafer processing unit that processes wafers W one by one. FIG. 13 is a diagram illustrating a configuration example of a processing unit according to a modification;

As shown in FIG. 13, the processing unit 200 according to the modification includes a chamber 220, a substrate holding mechanism 230, a nozzle 240, and a recovery cup 250.

The chamber 220 accommodates the substrate holding mechanism 230 , the nozzle 240 and the collection cup 250 . An FFU (Fan Filter Unit) 221 is provided on the ceiling of the chamber 220 . FFU 221 creates a downflow within chamber 220 .

The substrate holding mechanism 230 includes a holding portion 231 , a support portion 232 and a driving portion 233 . The holding part 231 holds the wafer W horizontally. The column portion 232 is a member extending in the vertical direction, the base end portion of which is rotatably supported by the drive portion 233, and the tip portion of which supports the holding portion 231 horizontally. The drive section 233 rotates the support section 232 around the vertical axis. The substrate holding mechanism 230 rotates the supporting part 231 supported by the supporting part 232 by rotating the supporting part 232 using the driving part 233, thereby rotating the wafer W held by the supporting part 231. .

The nozzle 240 is arranged above the wafer W held by the holding part 231 and supplies various processing liquids to the wafer W.

The collection cup 250 is arranged to surround the holding portion 231 and collects the processing liquid scattered from the wafer W due to the rotation of the holding portion 231 . A drain port 251 is formed at the bottom of the recovery cup 250 , and the processing liquid collected by the recovery cup 250 is discharged to the outside of the processing unit 200 through the drain port 251 . An exhaust port 252 is formed at the bottom of the collection cup 250 to discharge the gas supplied from the FFU 221 to the outside of the processing unit 200 .

The processing unit 200 further includes an etchant supply section 260 and a rinse liquid supply section 270 .

The etchant supply unit 260 includes an etchant supply source 261 and a valve 262 and supplies the etchant supplied from the etchant supply source 261 to the nozzle 240 . The rinse liquid supply unit 270 includes a rinse liquid supply source 271 and a valve 272 and supplies the rinse liquid (deionized water or the like) supplied from the rinse liquid supply source 271 to the nozzle 240 .

In such a processing unit 200, etching processing is first performed. In the etching process, the valve 262 is opened for a predetermined time to supply the etchant to the wafer W held and rotated by the substrate holding mechanism 230 .

Subsequently, the processing unit 200 performs a rinse process. In the rinsing process, the valve 272 is opened for a predetermined time to supply the rinsing liquid to the wafer W held and rotated by the substrate holding mechanism 230 . After that, in the processing unit 200, a drying process is performed. In the drying process, the wafer W is dried by increasing the rotation speed of the wafer W to shake off the rinse liquid from the wafer W. FIG. When the drying process is completed, the substrate processing for one wafer W is completed.

Thus, the substrate processing according to the embodiment can also be applied to a single-wafer processing unit that processes wafers W one by one.

[Other variations]
In the above-described embodiment, in the laminated film formed on the wafer W, the polysilicon film 12 and each of the plurality of silicon oxide films 11 are formed adjacent to each other in the vertical direction. structure is not limited to this. For example, in the laminated film, each of the plurality of silicon oxide films 11 and another film formed adjacent to each of the plurality of silicon oxide films 11 may be formed adjacent to each other in the horizontal direction.

Further, in the above embodiment, after performing the etching process (step S101) of the wafer W using the etchant to which the metal salt is added, the surface of the wafer W is coated with SC2 (mixed solution of hydrochloric acid and hydrogen peroxide). A removal treatment may be performed to remove residual metal salts. Further, in such a case, other films formed adjacent to each of the plurality of silicon oxide films 11 are preferably not metal-containing films.

As described above, the substrate processing method according to the embodiment includes a step of preparing a substrate (for example, wafer W) and a step of etching the substrate. The step of preparing a substrate prepares a substrate having a laminated film including a plurality of silicon oxide films (for example, silicon oxide film 11) with different film thicknesses. In the step of etching the substrate, the substrate is etched with an etchant to which at least one of hydrochloric acid, a metal salt and a surfactant is added. Therefore, according to the substrate processing method according to the embodiment, it is possible to reduce variations in the etching rate for each silicon oxide film in the technique of etching a laminated film including a plurality of silicon oxide films having different film thicknesses.

The concentration of each of hydrochloric acid and metal salt in the etching solution may be 0.5 wt% or more and 5 wt% or less. This makes it possible to reduce variations in etching rate for each silicon oxide film regardless of the type of metal salt. Further, by setting the concentration of the metal salt in the etching liquid to 5 wt % or less, contamination of the substrate with metal can be suppressed.

The concentration of the surfactant in the etchant may be 0.5 wt% or more and 5 wt% or less. This makes it possible to reduce variations in etching rate for each silicon oxide film regardless of the type of surfactant. Further, by setting the concentration of the surfactant in the etching liquid to 5 wt % or less, it is possible to suppress the organic matter (dirt) removed by the surfactant from remaining on the surface of the substrate.

The substrate processing method according to the embodiment may further include a step of removing metal salts remaining on the surface of the substrate in SC2 after the step of etching the substrate. As a result, contamination of the substrate with metal can be suppressed.

The embodiments disclosed this time should be considered illustrative in all respects and not restrictive. Indeed, the above-described embodiments may be embodied in many different forms. Also, the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

In addition, the following additional remarks are disclosed regarding the above embodiment.
(Appendix 1)
Preparing a substrate having a laminated film containing a plurality of silicon oxide films with different film thicknesses;
and etching the substrate with an etchant to which hydrochloric acid is added.
(Appendix 2)
Preparing a substrate having a laminated film containing a plurality of silicon oxide films with different film thicknesses;
and a step of etching the substrate with an etchant to which a metal salt is added.
(Appendix 3)
Preparing a substrate having a laminated film containing a plurality of silicon oxide films with different film thicknesses;
and a step of etching the substrate with an etchant to which a surfactant is added.
(Appendix 4)
The laminated film is a laminated film further comprising another film formed adjacent to each of the plurality of silicon oxide films,
4. The substrate processing method according to any one of Appendices 1 to 3, wherein the other film is selected from at least one of a silicon film, a polysilicon film, a silicon nitride film and a metal-containing film.
(Appendix 5)
5. The substrate processing method according to appendix 4, wherein in the laminated film, the other film and each of the plurality of silicon oxide films are formed adjacent to each other in a vertical direction or a horizontal direction.
(Appendix 6)
6. The substrate processing method according to any one of appendices 1 to 5, wherein the film thickness of the plurality of silicon oxide films is 1 nm or more and 30 nm or less.
(Appendix 7)
7. The substrate processing method according to any one of appendices 1 to 6, wherein the etchant contains hydrofluoric acid.
(Appendix 8)
8. The substrate processing method according to appendix 7, wherein the concentration of the hydrofluoric acid in the etching liquid is 0.1 wt % or more and 50 wt % or less.
(Appendix 9)
The substrate processing method according to appendix 1, wherein the concentration of the hydrochloric acid before being added to the etching solution is 35 wt % or more and 37 wt % or less.
(Appendix 10)
The substrate processing method according to appendix 2, wherein the metal salt is an alkali metal halide or an alkaline earth metal halide.
(Appendix 11)
the alkali metal halide comprises at least one of Li, Na, K, Rb and Cs;
11. The substrate processing method according to Appendix 10, wherein the alkaline earth metal halide contains at least one of Mg, Ca, Sr and Ba.
(Appendix 12)
The substrate processing method according to appendix 1, wherein the concentration of each of the hydrochloric acid and the metal salt in the etching solution is 0.5 wt % or more and 5 wt % or less.
(Appendix 13)
The substrate processing method according to Appendix 3, wherein the surfactant is a cationic surfactant or an anionic surfactant.
(Appendix 14)
the cationic surfactant is n-octylamine hydrochloride (OACl) or n-octyltrimethylammonium chloride (OTMACl);
14. The substrate processing method according to Appendix 13, wherein the anionic surfactant is sodium dodecylbenzenesulfonate (SDBS).
(Appendix 15)
15. The substrate processing method according to any one of appendices 3, 13, and 14, wherein the concentration of the surfactant in the etching solution is 0.5 wt % or more and 5 wt % or less.
(Appendix 16)
The substrate processing method according to appendix 2, further comprising a step of removing the metal salt remaining on the surface of the substrate in SC2 after the step of etching the substrate.
(Appendix 17)
a processing tank for storing an etchant to which hydrochloric acid has been added;
and a control unit that controls each part,
The control unit
A substrate processing apparatus for etching a substrate by immersing a substrate having a laminated film including a plurality of silicon oxide films with different film thicknesses in the etchant stored in the processing bath.
(Appendix 18)
a processing tank for storing an etchant to which a metal salt has been added;
and a control unit that controls each part,
The control unit
A substrate processing apparatus for etching a substrate by immersing a substrate having a laminated film including a plurality of silicon oxide films with different film thicknesses in the etchant stored in the processing bath.
(Appendix 19)
a processing tank for storing an etchant to which a surfactant is added;
and a control unit that controls each part,
The control unit
A substrate processing apparatus for etching a substrate by immersing a substrate having a laminated film including a plurality of silicon oxide films with different film thicknesses in the etchant stored in the processing bath.

1 substrate processing apparatus 7 control unit 10 silicon substrate 11 silicon oxide film 12 polysilicon film 15 groove 16p water cluster 16s spherical structure 60 etching processing unit 61 processing tank 100 inner tank 110 outer tank 120 circulation unit 130 etching liquid supply unit W wafer

Claims

Preparing a substrate having a laminated film containing a plurality of silicon oxide films with different film thicknesses;
and etching the substrate with an etchant to which hydrochloric acid is added.
Preparing a substrate having a laminated film containing a plurality of silicon oxide films with different film thicknesses;
and a step of etching the substrate with an etchant to which a metal salt is added.
Preparing a substrate having a laminated film containing a plurality of silicon oxide films with different film thicknesses;
and a step of etching the substrate with an etchant to which a surfactant is added.
The laminated film is a laminated film further comprising another film formed adjacent to each of the plurality of silicon oxide films,
4. The substrate processing method according to claim 1, wherein said other film is selected from at least one of a silicon film, a polysilicon film, a silicon nitride film and a metal-containing film.
5. The substrate processing method according to claim 4, wherein in said laminated film, said another film and each of said plurality of silicon oxide films are formed adjacent to each other in a vertical direction or a horizontal direction.
The substrate processing method according to any one of claims 1 to 3, wherein the film thickness of the plurality of silicon oxide films is 1 nm or more and 30 nm or less.
The substrate processing method according to any one of claims 1 to 3, wherein the etchant contains hydrofluoric acid.
The substrate processing method according to claim 7, wherein the concentration of said hydrofluoric acid in said etching liquid is 0.1 wt% or more and 50 wt% or less.
The substrate processing method according to claim 1, wherein the concentration of said hydrochloric acid before being added to said etching liquid is 35 wt% or more and 37 wt% or less.
The substrate processing method according to claim 2, wherein the metal salt is an alkali metal halide or an alkaline earth metal halide.
the alkali metal halide comprises at least one of Li, Na, K, Rb and Cs;
11. The substrate processing method of claim 10, wherein the alkaline earth metal halide includes at least one of Mg, Ca, Sr and Ba.
The substrate processing method according to claim 1, wherein the concentration of said hydrochloric acid in said etchant is 0.5 wt% or more and 5 wt% or less.
The substrate processing method according to claim 3, wherein the surfactant is a cationic surfactant or an anionic surfactant.
the cationic surfactant is n-octylamine hydrochloride (OACl) or n-octyltrimethylammonium chloride (OTMACl);
14. The substrate processing method of claim 13, wherein the anionic surfactant is sodium dodecylbenzenesulfonate (SDBS).
The substrate processing method according to any one of claims 3, 13 and 14, wherein the concentration of said surfactant in said etching liquid is 0.5 wt% or more and 5 wt% or less.
The substrate processing method according to claim 2, further comprising a step of removing the metal salt remaining on the surface of the substrate in SC2 after the step of etching the substrate.
a processing tank for storing an etchant to which hydrochloric acid has been added;
and a control unit that controls each part,
The control unit
A substrate processing apparatus for etching a substrate by immersing a substrate having a laminated film including a plurality of silicon oxide films with different film thicknesses in the etchant stored in the processing tank.
a processing tank for storing an etchant to which a metal salt has been added;
and a control unit that controls each part,
The control unit
A substrate processing apparatus for etching a substrate by immersing a substrate having a laminated film including a plurality of silicon oxide films with different film thicknesses in the etchant stored in the processing bath.
a processing tank for storing an etchant to which a surfactant is added;
and a control unit that controls each part,
The control unit
A substrate processing apparatus for etching a substrate by immersing a substrate having a laminated film including a plurality of silicon oxide films with different film thicknesses in the etchant stored in the processing bath.