TWI830177B - Substrate processing apparatus and substrate processing method - Google Patents

Abstract

The substrate processing apparatus 1 of the present invention includes: chemical liquid preparation units 101 and 103 for preparing a chemical liquid containing a solute that acts as an etchant and is ionized in the liquid; and a processing chamber 11 for accommodating the substrate S. , the substrate S is etched with the chemical solution; the ion removal part 121 removes at least part of the specific ion species in the chemical solution; and the chemical solution supply parts 105, 113 form the flow path of the aforementioned chemical solution. The aforementioned flow path supplies the chemical solution sent from the chemical solution preparation units 101 and 103 to the substrate S in the processing chamber 11 through the ion removal unit 121 . The substrate S including fine patterns can be etched at a good etching rate.

Description

Substrate processing device and substrate processing method

The present invention relates to a substrate processing apparatus and a substrate processing method for etching a substrate using a chemical solution containing an ionized solute, and in particular to a technology for etching narrow areas such as fine patterns.

The manufacturing process of electronic components such as semiconductor devices and liquid crystal display devices includes an etching process in which a substrate is partially etched and removed using a chemical solution to form a desired pattern. In recent years, especially with the miniaturization of patterns and the three-dimensional structuring of electronic components, it is sometimes required to form not only concave portions with relatively wide openings in the etching process, but also elongated ones with narrow and deep openings. The concave part.

For example, Japanese Patent Application Laid-Open No. 2021-027125 (Patent Document 1) describes a method of manufacturing a semiconductor storage device as follows. In this method of manufacturing a semiconductor storage device, two thin films having mutually different compositions are alternately and repeatedly laminated on the surface of a semiconductor substrate to form a laminated body. One of the thin films in the laminate is selectively removed by an etching process, thereby realizing a three-dimensional structure.

Patent Document 1 does not clearly describe the dimensions of each part of the structure. However, it is known that the etching rate is extremely reduced when etching a narrow area where the opening size of the concave portion of the pattern to be etched is as small as 10 nm or less. As will be described later, it is estimated that one of the causes of this phenomenon is that an electric double layer is formed at the interface between the chemical liquid and the surface of the etching object in contact with the chemical liquid. The electric field thus formed exerts an influence on the chemical liquid. The ions in have repulsive force.

The present invention is made in view of the above problems, and an object thereof is to provide a technology that can etch a substrate including a fine pattern with a good etching rate in a substrate processing apparatus and a substrate processing method for etching a substrate.

In order to achieve the above object, one aspect of the present invention is a substrate processing apparatus, including: a chemical liquid preparation unit for preparing a chemical liquid containing a solute that acts as an etchant and is ionized in the liquid; and a processing chamber. , is for accommodating the substrate, and etching the aforementioned substrate with the aforementioned chemical solution; the ion removal unit is for removing at least the specific ion species in the aforementioned chemical solution that do not contribute to the etching of the narrow portion or hinder the reaction of etching the aforementioned narrow portion. A part is removed; and a chemical liquid supply part forms a flow path for the chemical liquid, and the flow path is for supplying the chemical liquid sent out by the chemical liquid preparation part to the substrate in the processing chamber through the ion removal part. .

In addition, in order to achieve the above object, another aspect of the present invention is a substrate processing method, which includes the steps of preparing a medicinal solution, wherein the medicinal solution contains a solute that acts as an etchant and is ionized in the liquid; The chemical liquid is sent to the ion removal part, and at least a part of the specific ion species in the chemical liquid that does not contribute to the etching of the narrow area or hinders the etching reaction of the narrow area is added to the ion removal part. a step of removing; and a step of supplying the chemical liquid to the substrate before passing through the ion removal part to perform an etching process.

In the invention thus constituted, the content of specific ion species in the chemical solution supplied to the substrate is artificially reduced. A part of the solute contained in the medical solution is ionized, so that the ions generated by ionization and the unionized solute coexist in the medical solution. Usually, ions and unionized solutes exist in the liquid at concentrations that maintain ionization equilibrium. In the present invention, since specific ion species are removed from the chemical solution and then supplied to the substrate, the chemical solution supplied to the substrate is in a state of losing ionization balance.

In the following description, the "narrow portion" refers to a recess formed in advance on the substrate to be processed or a structure laminated on the substrate, or a recess formed as a result of the etching process. It is assumed that the diameter of the opening, The minimum dimensions such as width are approximately 10 nanometers or less.

The details will be described later, but based on the findings of the inventor of this case, it is determined that the contribution of ion species included in the chemical solution as an etchant to the etching process becomes smaller in narrow areas, and this is the case during etching of narrow areas. Causes the etching rate to decrease. On the other hand, it is judged that the retention of ions that do not contribute to the treatment hinders the supply of other etchants to the processed parts.

Therefore, in the present invention, at least part of the specific ion species that contribute little to the narrow site etching process in the etchant in the chemical solution is removed, thereby efficiently supplying the etchant that contributes to the process to the processed site. . This approach can improve the efficiency of the etching process for narrow areas and suppress a decrease in the etching rate.

In addition, even if a part of the ionic species is removed from the chemical solution, as time passes, the ionization equilibrium will shift and the ionic species will increase again. Therefore, the removal of ionic species is related to the supply of It is better to do this before applying it to the substrate. In order to achieve this, in the present invention, an ion removal unit is provided on the flow path for supplying the prepared chemical solution to the substrate.

According to the invention thus constituted, by reducing the content of ion species that do not contribute to the etching process in the chemical solution, it is possible to suppress a decrease in the etching rate even in a substrate having a narrow portion with an opening size of 10 nm or less, for example. Etches well.

The foregoing and other objects and novel features of the present invention will be more fully elucidated by referring to the appended drawings and reading the following detailed description. However, the drawings are for illustrative purposes only and are not intended to limit the scope of the present invention.

1 to 7: Substrate processing device

10:Substrate processing unit

11: Processing chamber

13:Substrate holding part

15: Liquid ejection part

15a:Nozzle

15b: Swing arm

19:Control unit

60:Substrate processing unit

61: Processing tank

100,200,300,400,500,600,700:Substrate processing unit

101,201,301,401,501,601,701: Mixer (liquid preparation department)

103,203,303,403,503,603,703: Storage tank (liquid preparation part, storage container)

105, 205, 305, 305a, 305b, 405, 405a, 405b, 505, 605, 705, 705a, 705b: piping (chemical liquid supply part, circulation flow path)

107,207,307,407,507,607,707: Output piping (supply piping)

111,211,311,411,511,611,711: Temperature regulator

113,213,313,413,513,613,713: Liquid delivery pump (liquid supply department)

115,215,315,415,515,615,715: Particle filter

117,317,321,323,417,421,423,517,521,523,525,533,535,617,717,721,723: Control valve (concentration adjustment part)

121,221,223,325,425,525,621,725: Ion removal filter (ion removal part)

217:Control pump

327,427,527,727: Concentration meter (concentration measurement part)

531: Regeneration piping (regeneration part)

A:Flow path

AS: air gap

B:Flow path

Ci: (hydrogen difluoride ion) concentration

CS: liquid medicine

Cm: (hydrogen fluoride) concentration

E1, E2, E3: electrodes

I: insulation layer

H: memory hole

M1:Material

M2:Material

Ls: sacrificial layer

LSL1: lower limit value

LSL2: lower limit value

R: Expanded diameter part

R1, R2, R3, R4: concave part

S,S1,S2,S3:Substrate

USL1: upper limit value

USL2: upper limit value

P: memory column

W: opening size

W1: opening width

W2: Size (opening size)

W3: opening width

W4: opening width

[Fig. 1A] is a diagram showing an example of a structure on a substrate that is a subject of the present invention.

[Fig. 1B] Fig. 1B is a diagram showing an example of a structure on a substrate that is a subject of the present invention.

[Fig. 2A] is a diagram schematically showing a part of the process of forming a three-dimensional NAND (NOT-AND; reverse-and) structure.

[Fig. 2B] is a diagram schematically showing a part of the process of forming a three-dimensional NAND structure.

[Fig. 2C] is a diagram schematically showing a part of the process of forming a three-dimensional NAND structure.

[Fig. 3] Fig. 3 is a diagram showing another example of a structure on a substrate that is a subject of the present invention.

[Fig. 4A] is a diagram showing an example corresponding to the opening size.

[Fig. 4B] is a diagram showing an example corresponding to the opening size.

[Fig. 4C] is a diagram showing an example corresponding to the opening size.

[Fig. 5A] is a diagram showing an example of a part of experimental results.

[Fig. 5B] is a diagram showing an example of a part of experimental results.

[Fig. 6A] is a diagram for explaining the examination of the experimental results.

[Fig. 6B] is a diagram for explaining the examination of the experimental results.

[Fig. 7A] is a diagram showing the schematic configuration of the first embodiment of the substrate processing apparatus.

[FIG. 7B] is a diagram showing the schematic structure of the second embodiment of the substrate processing apparatus.

[FIG. 7C] is a diagram showing the schematic structure of the third embodiment of the substrate processing apparatus.

[Fig. 8A] is a diagram showing the schematic structure of the fourth embodiment of the substrate processing apparatus and the operation of the structure.

[Fig. 8B] is a diagram showing the schematic structure of the fourth embodiment of the substrate processing apparatus and the operation of the structure.

[Fig. 9] is a diagram showing the schematic configuration of a fifth embodiment of a substrate processing apparatus.

[Fig. 10A] is a diagram showing the schematic configuration of a sixth embodiment of a substrate processing apparatus.

[FIG. 10B] is a diagram showing the schematic structure of the seventh embodiment of the substrate processing apparatus.

Several embodiments of the substrate processing apparatus and substrate processing method of the present invention will be described below. The present invention relates to etching processing of substrates. Before describing the invention, the structure of a substrate that is an object of the invention and a device formed on the surface of the substrate will be exemplified.

1A and 1B are diagrams showing examples of structures on a substrate that are objects of the present invention. FIG. 1A shows an example of a structure that is present in one stage of the manufacturing process of a replacement gate (RG) three-dimensional NAND flash memory (flash memory). In this structure, a plurality of insulating layers I parallel to the surface of the substrate S1 are arranged with slight gaps between each other, and a memory is erected perpendicularly to the surface of the substrate S1 so as to penetrate these insulating layers I. Pillar(memory pillar)P.

In addition, FIG. 1B shows an example of a structure that is present in one stage of the manufacturing process of a floating gate (FG) three-dimensional NAND flash memory. This structural system is provided with a memory hole H perpendicular to the substrate S2. The side wall of the memory hole H has a structure in which the diameter is locally expanded to form an expanded diameter portion R.

The etching process is performed for the purpose of forming such a structure or for the purpose of treating the surface of the structure formed as such. For example, the structure shown in Figure 1B is formed in the following manner.

2A to 2C are diagrams schematically showing a part of the process of forming a three-dimensional NAND structure. As shown in FIG. 2A , first, two thin films made of mutually different materials M1 and M2 are alternately laminated on the surface of the substrate S2 . Next, as shown in FIG. 2B , memory holes H are formed to penetrate these laminated bodies. The memory hole H can be formed by a combination of photolithographic mask formation and anisotropy etching, for example. Further, as shown in FIG. 2C , at least a portion of the surface facing the memory hole H is removed by an etching process that selectively dissolves the material M2. In this way, a three-dimensional structure is formed as shown in Figure 1B.

Similarly, the structure shown in FIG. 1A can also be achieved by alternately stacking a layer of the material of the insulating film I on the substrate S1 and a layer (sacrificial layer) that is finally removed by etching, and then the sacrificial layer is formed after the memory pillar P is formed. The layer is removed by etching.

The combination of the material M1 that is ultimately left in the device as a functional layer and the material M2 that is at least partially removed by selective etching can be considered, for example, SiO ₂ (silicon dioxide) and SiN (silicon nitride), SiO ₂ and polycrystalline silicon, There are various combinations of Si (silicon) and SiGe (Silicon-germanium; silicon germanium), TiO ₂ (titanium dioxide) and Si, etc. The present invention is not limited to these materials. In addition, in the above combination, the material remaining in the device and the material removed by etching can also be exchanged.

FIG. 3 is a diagram showing another example of a structure on a substrate that is a subject of the present invention. In this example, a gap called an air spacer is formed in the semiconductor device formed by laminating a plurality of functional layers on the surface of the substrate S3. In this example, as part of the manufacturing process of devices called nanosheet devices such as transistors and switching elements, the air gap AS is provided for insulation between the electrodes E1 to E3. The air gap AS is formed by etching and removing the sacrificial layer Ls formed between the electrodes E1 to E3.

As described above, various device structures can be considered as device structures to which the present invention is applicable. In particular, the present invention can be appropriately applied to device manufacturing with a process specification of 10 nanometers or less. In devices with such fine structures, in order to achieve high density, the three-dimensional structure as described above is often adopted. Therefore, technology for etching narrow areas at the nanometer level is required.

The following describes the problems in "narrow area etching" based on the findings of the present inventor and the solutions in this embodiment. In the etched parts of the substrate for etching treatment, on the surface In the "narrow area" where the surface is receded compared to the surrounding area and the opening size is small, there is a phenomenon that the etching rate is significantly lower than when etching a recessed area with a larger opening size.

In addition, the "narrow part" here is assumed to be a recess formed in advance on the substrate to be processed or a structure laminated on the substrate, or a recess formed as a result of the etching process, and the diameter and width of the opening are The smallest size is about 10 nanometers or less. More narrowly speaking, the minimum size of the opening is set to 5 nanometers or less. Hereinafter, the "minimum size of the opening" is simply referred to as the "opening size". In addition, when referred to as "substrate" below, it includes not only base materials such as semiconductor wafers and glass substrates, but also structures composed of various functional layers stacked on the surface of the base material.

4A to 4C are diagrams showing examples corresponding to the "opening size" in this specification. As shown in the cross-sectional view of FIG. 4A , when the substrate S is provided with a small and deep recessed portion R1 , the opening width W1 of the recessed portion R1 is the opening size. When the recess R1 is, for example, a hole with a circular cross-section, the diameter of the hole corresponds to the opening size. On the other hand, as shown in FIG. 4B , when the opening shape is a recessed portion R2 having anisotropy, the smallest dimension W2 of the recessed portions R2 corresponds to the opening size.

In addition, as shown in FIG. 4C , when a recess R4 is further formed inside the recess R3 provided in the substrate S, the opening width W3 of the recess R3 and the opening width W4 of the recess R4 may be equivalent to the opening size referred to in this specification. . That is, when the opening width W3 of the recessed portion R3 is 10 nanometers or less, the entire recessed portion R3 corresponds to the "narrow portion". On the other hand, even if the opening width W3 of the recessed portion R3 is larger than 10 nanometers, when the opening width W4 of the recessed portion R4 is 10 nanometers or less, each recessed portion R4 corresponds to a "narrow portion."

The findings obtained by the inventor of the present case through various experiments will be described below with reference to FIGS. 5A to 6B . FIGS. 5A and 5B are diagrams showing examples of part of experimental results, and FIGS. 6A and 6B are diagrams for explaining examination of the experimental results. The inventor of this case conducted experiments as described below. The object to be etched is the SiO ₂ layer in a laminate of silicon (Si) and silicon dioxide (SiO ₂ ). Hydrofluoric acid (HF) aqueous solution was used as an etching solution, and an etching process was performed to selectively remove the SiO ₂ layer to study changes in the etching rate during etching of narrow areas. More specifically, various combinations of the hydrofluoric acid concentration in the chemical solution and the opening size W of the narrow portion were changed, and the etching rate was measured. Here, "blanket" is a so-called plain film without recesses, which is equivalent to the state of W=∞.

As shown in FIG. 5A , the higher the concentration of hydrofluoric acid in the chemical solution, the higher the etching rate, and the smaller the opening size W of the narrow portion, the lower the etching rate. The etching reaction of silicon dioxide based on hydrofluoric acid can be expressed by the following reaction formula: [Formula 1] SiO ₂ +6HF → SiF ₆ ^2- +2H ₂ O

It is said that there are actually contributions from unseparated hydrogen fluoride (HF, more specifically, associated molecules (HF) ₂ ) and contributions from dihydrogen fluoride ions (HF ₂ ^- ) generated by ionization. As a formula that quantitatively shows the etching rate Re based on these etchants, Formula 2 described in the upper part of FIG. 5B is known.

Apply Equation 2 to the experimental results shown in Figure 5A, and calculate each coefficient a, b, c, d by, for example, fitting a curve based on the least square method. The results are shown in the lower part of Figure 5B Show. All coefficients become smaller as the opening size W becomes smaller. However, compared with the decrease in the coefficients a and b of the terms indicating the contribution of unseparated hydrogen fluoride molecules (HF), the decreases in the coefficients c and d of the terms indicating the contribution of difluoride ions (HF ₂ ^- ) are greater. Significantly. In addition, R ² is the coefficient of determination, and all opening sizes are close to 1, indicating that the accuracy of the curve approximation is good.

From this result the following can be said. In the etching of narrow areas, although the proportion of contribution of hydrogen difluoride ions is greatly reduced and the etching rate is reduced, the contribution of hydrogen fluoride molecules is still effective. Especially when the opening size W is 3 nm, it can be said that there is almost no contribution from hydrogen difluoride ions. This result can be explained by, for example, the influence of the electric double layer formed at the interface between the etching object and the chemical solution as described below.

6A is a diagram schematically showing the general relationship between the zeta potential (Zeta Potential) at the interface between the constituent materials (Si, SiO ₂ ) of the etching object and the aqueous solution and the hydrogen ion concentration (pH) of the aqueous solution. The bounded potential typically represents the potential that appears on the surface of a substance due to the electrical double layer formed at the interface between the substance and the aqueous solution. As the pH value of the aqueous solution becomes higher, the point where the boundary potential moves to the negative side, Si and SiO ₂ tend to become more similar. SiO ₂ shown by the solid line in the figure has a positive potential under strong acid; on the other hand, as shown by the dotted line, Si also has a negative potential under strong acid. The pH value when the potential reaches zero in SiO ₂ is about 2 to 3. Therefore, in a weakly acidic to alkaline aqueous solution, the threshold potential is a negative potential.

That is, in the weakly acidic hydrofluoric acid aqueous solution that is the etching chemical solution, as shown in FIG. 6B , the surface of the etching object carries a negative potential. This negative potential does not affect hydrogen fluoride molecules (HF, (HF) ₂ ), which are electrically neutral molecules, but has a repulsive force on hydrogen difluoride ions (HF ₂ ^- ), which are negative ions. Therefore, hydrogen difluoride ions (HF ₂ ^- ) are repelled by the object to be etched, and the probability of approaching the surface of the object to be etched is reduced, resulting in the inability to contribute to etching. This repulsive force can be considered to be within a range of approximately the Debye length λ _D from the surface of the object to be etched.

The Debye length is a physical property value that serves as a reference for the thickness of the electric double layer formed at the interface. As the concentration of the solute in the aqueous solution increases, the Debye length becomes smaller. For example, a solute concentration of 0.01M (volume The Debye length is about 1 nanometer when the solute concentration is 0.1M, and the Debye length is about 10 nanometers when the solute concentration is 0.1M. The Debye length in this experimental system is about 2.5 nanometers.

In this way, as shown by the dotted line in FIG. 6B , a potential barrier with a thickness of about the Debye length λ _D for hydrogen difluoride ions will be formed on the surface of the etching object. In the recessed portion R5 with a relatively large opening size W5 (for example, 10 nm or more), since the potential barrier extends along the inner wall of the recessed portion R5, hydrogen difluoride ions can also enter the interior of the recessed portion R5. Therefore, in this case, the etching effect of hydrogen difluoride ions can be expected to a certain extent.

On the other hand, in the recess R6 whose opening size W6 is relatively small (for example, 5 nanometers or less), the potential barrier is formed to close the opening of the recess R6. Therefore, hydrogen difluoride ions can hardly enter the inside of the recessed portion R6. Therefore, etching efficiency based on hydrogen difluoride ions cannot be expected.

On the other hand, unionized hydrogen fluoride molecules (HF, (HF) ₂ ) are not affected by the potential barrier. However, as still shown in Figure 5B, the smaller the opening size of the narrow part, the smaller the coefficients a and b. It is known that the etching efficiency based on these molecules is also reduced in narrow areas. It can be considered that ions that cannot enter the inside of the recess remain around the opening, and these ions prevent molecules from entering the recess.

Therefore, each embodiment of narrow site etching described below is provided with a structure for removing at least part of the ion species that do not contribute to the etching reaction from the chemical solution supplied to the object to be etched as described above. By removing ion species that do not contribute to the etching reaction or ion species that hinder the reaction, a decrease in the etching rate can be suppressed.

In the above-mentioned etching of silicon dioxide based on a hydrofluoric acid aqueous solution, since the surface of the etching object has a negative potential, the anion that does not contribute to the etching reaction is specifically difluoride. While removing hydrogen ions, the chemical solution is supplied to the object to be etched. This approach can maintain the etching effect based on hydrogen fluoride molecules and suppress the decrease in etching rate.

The same phenomenon occurs in other material systems. For example, when selectively removing the titanium nitride layer from a laminate of silicon (Si) and titanium nitride (TiN), an aqueous hydrogen peroxide (H ₂ O ₂ ) solution can be used as an etching chemical solution. Although an oxide film (titanium dioxide; TiO ₂ ) is formed on the surface of the exposed titanium nitride, the oxide film can be removed by a dissolution reaction based on hydrogen ions (H ⁺ ). Therefore, ideally, the medical solution should be rich in hydrogen ions.

On the other hand, regarding the titanium nitride layer, the oxidative dissolution reaction of unionized hydrogen peroxide (H ₂ O ₂ ) or hydrogen peroxide ions (HO ₂ ⁻ ) is dominant. In this case, since the surface of the object to be etched has a negative potential, hydrogen peroxide ions as anions do not contribute to the etching of the narrow portion. By removing hydrogen peroxide ions from the chemical solution and increasing the proportion of unionized hydrogen peroxide, the decrease in etching rate can be suppressed.

As mentioned above, generally speaking, in insulating materials, the boundary potential is negative except under strong acid. However, there are also metal-based materials such as alumina (Al ₂ O ₃ ) where the critical potential is positive in a wider range. For example, the critical potential is still positive even under neutral conditions (pH=7). In this case, the cations in the chemical solution do not contribute to the etching reaction. Therefore, it is expected that reduction in etching rate can be suppressed by removing cations from the chemical solution.

In this way, in etching a narrow area using a chemical solution containing a solute ionized in the liquid as an etchant, specific ion species that contribute little to the etching reaction are removed from the chemical solution and supplied to the etching target object. , can suppress the decrease in etching rate. The ion species to be removed depends on the combination of the etching object and the chemical solution. That is, based on the relationship between the function of the chemical solution as an etchant and the polarity of the potential of the etching object in the chemical solution, it can be determined which ion species should be removed.

In addition, to what extent the opening size corresponds to the "narrow part" changes depending on the combination of the etching object and the chemical solution and the concentration of the chemical solution. Generally speaking, the area that should be regarded as a narrow part can be set based on the magnitude of the boundary potential caused by the electric double layer formed at the interface between the two and the Debye length, which is a reference for the actual effective range of influence of the boundary potential. size.

In the combination of the etching object and the chemical solution that is widely used today, the Debye length is about several nanometers. Therefore, when the opening size is about 10 nanometers or less, it is considered that the influence of ion repulsion caused by the electric double layer at the interface appears. This effect is significant especially when the opening size is below 5 nm.

Based on the above principles, several embodiments of a substrate processing apparatus equipped with a structure for suppressing a decrease in etching rate in a narrow region will be exemplified below, and the structures of the embodiments will be described in sequence. In addition, when it is necessary to show a specific example of the etching process below, silicon dioxide etching using a hydrofluoric acid aqueous solution (diluted hydrofluoric acid) as a chemical solution is used as an example. However, even when the etching target object and the chemical solution are different from this, the configurations of each embodiment can be applied.

7A to 7C are diagrams showing the schematic configuration of the first to third embodiments of the substrate processing apparatus of the present invention. 8A and 8B are diagrams showing the schematic structure of the fourth embodiment of the substrate processing apparatus of the present invention and the operation of the structure. Moreover, FIG. 9 is a diagram showing the schematic structure of the fifth embodiment of the substrate processing apparatus.

The substrate processing apparatus 1 of the first embodiment shown in FIG. 7A includes a substrate processing unit 10, a chemical solution supply unit 100, and a control unit 19 for controlling the operation of each part of the apparatus. The substrate processing unit 10 is a main body for executing the etching process, and has a structure in which a substrate holding part 13 and a chemical liquid ejection part 15 are arranged in the processing chamber 11 . The processing chamber 11 receives the substrate S to be processed from the outside via an openable and closable shutter (not shown).

The substrate holding portion 13 rotates the substrate S about the vertical axis while holding the substrate S in a horizontal posture. As the substrate holding portion 13, a known spin chuck mechanism can be applied. The chemical liquid ejection part 15 has a structure in which a nozzle 15a is attached to the front end of the swing arm 15b. The nozzle 15 a sprays the etching chemical liquid toward the upper surface of the substrate S rotated by the substrate holding part 13 . The swing arm 15b swings about a predetermined swing axis to position the nozzle 15a relative to the substrate S.

In addition, since the substrate processing unit 10 configured in this way is well known, detailed description thereof is omitted. In addition, the structure of the substrate processing unit 10 is substantially the same in the 2nd embodiment to the 5th embodiment mentioned later. Therefore, in the following description, the same components as those described above are denoted by the same reference numerals, and description thereof is omitted.

The chemical solution supply unit 100 has a function of preparing an etching chemical solution and supplying it to the substrate processing unit 10 configured as above. The chemical solution supply unit 100 includes a mixer 101 that mixes a chemical supplied from an external supply source (not shown) and DIW (De-ionized Water) to prepare an etching chemical solution of a predetermined concentration. The agent is a solute having an etchant effect, for example, hydrogen fluoride in an etching process based on a hydrogen fluoride aqueous solution. In addition, for example, hydrogen peroxide is used in an etching process based on hydrogen peroxide water. In addition, various chemical substances such as electrolytes, liquids, and gases that act as etchants can be used as chemicals. The prepared chemical liquid CS is temporarily stored in the storage tank 103 .

The storage tank 103 is connected to a pipe 105 that forms a circulation channel for the chemical solution. The chemical solution sent from the lower part of the storage tank 103 circulates in the pipe 105 and returns to the upper part of the storage tank 103 . A temperature regulator 11 , a liquid supply pump 113 and a particle filter 115 are inserted in the pipe 105 in this order from the upstream side along the flow direction of the chemical solution. In addition, in the following description, when only "upstream side" or "downstream side" is called, these two refer to the upstream side and the downstream side respectively in the flow direction of the chemical liquid in the flow path starting from the storage tank.

The temperature regulator 111 adjusts the temperature of the chemical liquid flowing in the pipe 105 to a predetermined target temperature. The liquid supply pump 113 circulates the chemical liquid in the pipe 105 . The particle filter 115 removes foreign matter such as particles in the medical solution. Since these structures are well known, detailed descriptions are omitted.

An output pipe 107 is connected to the pipe 105 on the downstream side of the particle filter 115 , and the output pipe 107 communicates with the nozzle 15 a of the substrate processing unit 10 . A control valve 117 and an ion removal filter 121 are inserted into the output piping 107 . The control valve 117 performs on/off control and flow control of supplying the chemical liquid to the nozzle 15a.

The ion removal filter 121 has an ion exchange resin or an ion exchange membrane, and removes at least part of the anions or cations in the chemical solution. It is sufficient as long as the content of specific ion species in the chemical solution can be significantly reduced, and it is not necessary to remove all ions. There are already examples in which an ion removal filter is provided in the flow path for the purpose of removing foreign matter in the chemical solution. However, here, for the purpose of improving the etching rate in etching a narrow region, ion species that originally function effectively as an etchant are removed.

As the ion exchange resin for removing anions, for example, an ion exchange resin having a fourth-order ammonium group as a functional group can be suitably used. In addition, as the ion exchange resin for removing cations, for example, an ion exchange resin having functional groups such as sulfonic acid, sulfate ester, and carboxylic acid can be suitably used.

In a chemical solution containing a partially ionized solute, even if a specific ion species is temporarily removed, the concentration of the removed ion species will increase over time due to a shift in the ionization equilibrium. Therefore, it is preferable to remove ions immediately before supplying them to the substrate S. In order to achieve this, the ion removal filter 121 is inserted in the output pipe 107 branched from the circulation flow path. special In addition, if the ion removal filter 121 is disposed in the processing chamber 11, the length of the piping on the downstream side of the ion removal filter 121 can be minimized, and the chemical solution can be supplied to the substrate S before the ion concentration is restored.

It is also conceivable that the balance changes and the amount of the removed ion species is restored, resulting in a decrease in the concentration of other etchants in the chemical solution, especially unionized solutes that function effectively even in narrow areas. In order to suppress the decrease in etching rate caused by this, it is preferable to increase the solute concentration in the chemical solution in advance. For example, it is possible to use a chemical solution with a concentration that is approximately 10 times higher than that used when etching an etching object with a large opening size.

According to the above configuration, it is possible to supply the substrate S with a chemical solution that reduces the content of ion species that do not contribute to the etching of the narrow portion but become a cause of hindering the etching. Therefore, it is possible to suppress a decrease in the etching rate even during etching of a narrow area, and the etching process can be performed favorably.

The substrate processing apparatus 2 of the second embodiment shown in FIG. 7B includes a chemical solution supply unit 200 and the same substrate processing unit 10 and control unit 19 as those of the first embodiment. The chemical solution supply unit 200 includes a mixer 201, a storage tank 203, a pipe 205, a temperature regulator 211, a liquid supply pump 213, a particle filter 215, an output pipe 207, a control pump 217, and the like. These structures and functions are the same as the corresponding structures in the first embodiment.

In this embodiment, ion removal filters 221 and 223 are inserted in series in the output pipe 207 . One of the ion removal filters 221 and 223 performs anion removal, and the other performs cation removal. By removing both anions and cations in this way, the medical solution becomes mainly composed of unionized solutes. When unionized solutes make a large contribution to the etching reaction, by removing both anions and cations in this manner, a stable etching process that does not affect the surface potential of the object to be etched can be performed.

The substrate processing apparatus 3 of the third embodiment shown in FIG. 7C includes a chemical solution supply unit 300 and the same substrate processing unit 10 and control unit 19 as those of the first embodiment. In this embodiment, the ion removal filter is installed outside the processing chamber 11 and is configured to adjust the ion concentration in the chemical solution flowing in the circulation channel.

Specifically, the chemical solution supply unit 300 includes a mixer 301, a storage tank 303, a pipe 305, a temperature regulator 311, a liquid supply pump 313, a particle filter 315, an output pipe 307, a control valve 317, and the like. These structures and functions are the same as the corresponding structures in the first embodiment.

On the other hand, unlike the first embodiment, the pipe 305 between the liquid supply pump 313 and the particle filter 315 is divided into two. A control valve 321 is inserted into one pipe 305a. A control valve 323 and an ion removal filter 325 are inserted into the other pipe 305b. That is, the piping 305a has a function of forming a bypass flow path that bypasses the ion removal filter 325. In addition, the concentration meter 327 is inserted into the pipe 305 after the two pipes 305a and 305b are reunited.

As the concentration meter 327, when a concentration meter that measures the conductivity of a chemical solution to calculate the ion concentration is used, the concentration of various ion species can be measured systematically. This measurement method is also practical enough for situations where the ingredients of pharmaceuticals, such as hydrogen fluoride aqueous solution, are relatively simple. On the other hand, when it is necessary to measure the concentration of each ion species more closely, a concentration meter using, for example, infrared spectroscopy can be used. For example, this method can be used when a plurality of chemicals are mixed to prepare a pharmaceutical solution.

In this embodiment, the ion removal filter 325 is assembled in the circulation flow path upstream of the branch point that branches to the output piping 307 that finally sends the chemical solution to the substrate processing unit 10 . In this case, the removed ion species increase again over time by the equilibrium shift. Therefore, in this embodiment, the concentration meter 327 is installed in the circulation flow path and measures The ion concentration in the chemical solution is measured, and the ion removal amount of the ion removal filter 325 is adjusted according to the measurement results. Likewise in the second embodiment, a filter for removing anions and a filter for removing cations may be used in combination.

Specifically, the opening and closing of the control valves 321 and 323 is controlled based on the ion concentration measurement result of the concentration meter 327 . In this way, the flow path of the chemical solution is switched between two flow paths, one is a flow path passing through the piping 305a without the ion removal filter, and the other is a flow path passing through the piping 305b provided with the ion removal filter 325. Thereby, for example, ion removal is not performed when the chemical solution is not supplied to the substrate S. On the other hand, the flow path can be switched to perform ion removal before supplying the chemical solution, so that a chemical solution with an appropriate ion concentration can be supplied to the substrate S. Substrate S.

The substrate processing apparatus 4 of the fourth embodiment shown in FIG. 8A basically has the same structure as the third embodiment. That is, the chemical solution supply unit 400 of this embodiment includes a mixer 401, a storage tank 403, a pipe 405, pipes 405a and 405b branched from the pipe 405, a temperature regulator 411, a liquid supply pump 413, a particle filter 415, an output Piping 407, control valves 417, 421, 423, ion removal filter 425, concentration meter 427, etc. These structures and functions are the same as those in the third embodiment.

In this embodiment, as shown by the dotted arrow in FIG. 8A , a channel is added that allows the chemical (solute) supplied from an external supply source to be directly injected into the storage tank 403 without passing through the mixer 401 . This is a structure for performing so-called spiking, that is, temporarily injecting the medicine directly into the storage tank 403 to increase the concentration of the medicine in the storage tank 403 . The illustration of the detailed structure is omitted, but for example, reinforcement can be implemented by a combination of piping and a control valve that are branched from the external chemical supply piping.

Due to the circulation of the chemical solution through ion removal and the movement of the ionization equilibrium, the concentration of unionized solutes in the chemical solution in the storage tank 403 is reduced. This is the reason why the etching rate decreases during etching in narrow areas. Therefore, in this embodiment, the execution timing of ion removal by the ion removal filter 425 and the enhancement of the chemical is controlled as follows. In this way, both the concentration of unionized hydrogen fluoride and the concentration of dihydrogen fluoride ions can be maintained within appropriate ranges.

FIG. 8B is a timing chart showing concentration control in this embodiment. The mixer 401 mixes the chemical and DIW supplied from the outside at a predetermined ratio to adjust the hydrogen fluoride concentration Cm to a chemical liquid between the upper limit USL1 and the lower limit LSL1 of an appropriate range and supplies it to the storage tank 403 . The concentration meter 427 measures the concentration Cm of unionized hydrogen fluoride (HF) molecules and the concentration Ci of hydrogen difluoride ions (HF ₂ ⁻ ) in the chemical solution. The control unit 19 controls the opening and closing of the control valves 421 and 423 based on the concentration measurement results of hydrogen difluoride ions. Thereby, the flow path that does not pass through the ion removal filter as shown by arrow A in FIG. 8A is switched, and the flow path that passes through the ion removal filter 425 as shown by arrow B is switched.

Due to the shift of the ionization equilibrium generated in the circulating medical solution, the concentration Cm of hydrogen fluoride molecules in the medical solution in the storage tank 403 decreases with time. As shown by the white arrow in FIG. 8B , when the hydrogen fluoride concentration Cm decreases to the lower limit value LSL1 , intensification of injecting a certain amount of medicine into the storage tank 403 is performed. Thereby, the hydrogen fluoride concentration Cm temporarily increases and then decreases again. By repeating this process, the hydrogen fluoride concentration Cm in the chemical solution can be maintained within an appropriate range.

On the other hand, the concentration Ci of hydrogen difluoride ions increases when the chemical solution flows through the flow path A that does not pass through the ion removal filter, and decreases when the chemical solution flows through the flow path B that passes through the ion removal filter 425 . Therefore, when the hydrogen difluoride ion concentration Ci reaches the upper limit USL2 of the appropriate range, the flow path of the chemical solution is switched from flow path A to flow path B. This allows the ion removal effect of the ion removal filter 425 to be exerted function and reduce the ion concentration. Then, when the ion concentration Ci reaches the lower limit value LSL2 of the appropriate range, the flow path of the chemical solution is switched from the flow path B to the flow path A again. This stops the ion removal and increases the ion concentration due to the equilibrium shift. By repeating this procedure, the hydrogen difluoride ion concentration Ci in the chemical solution can be maintained within an appropriate range.

These two controls are independent of each other, and the enhanced execution time and flow path switching time may not be synchronized. However, it is judged that due to the strengthening of enforcement, the concentration of hydrogen difluoride ions Ci temporarily increased, thus causing a certain correlation between them.

In this embodiment, similarly to the third embodiment, a chemical solution with an appropriate ion concentration can be supplied to the substrate S. Furthermore, by strengthening as necessary, both the hydrogen fluoride concentration and the hydrogen difluoride ion concentration can be stabilized over a longer period of time. In this embodiment, an anion removal filter and a cation removal filter may be used together.

The substrate processing apparatus 5 of the fifth embodiment shown in FIG. 9 is equivalent to the substrate processing apparatus of the third embodiment with a filter regeneration function added thereto. Specifically, the chemical solution supply unit 500 of this embodiment includes a mixer 501, a storage tank 503, a pipe 505, a temperature regulator 511, a liquid supply pump 513, a particle filter 515, an output pipe 507, and control valves 517 and 523. ,525 etc. These structures and functions are the same as the corresponding structures in the third embodiment.

In addition, this embodiment is provided with a filter regeneration pipe 531 shown by a dotted line in the figure and control valves 533 and 535 inserted in the filter regeneration pipe 531 . The control valve 533 is provided in a pipe connected to an external sodium hydroxide (NaOH) supply source. On the other hand, the control valve 535 is provided in a pipe connected to an external DIW supply source.

When the ion removal treatment is continued, the ion exchange capacity of the ion exchange resin is reduced due to the entry of removed ions. By performing a regeneration process to discharge the ions that have entered, the ion exchange capability can be restored. For the anion exchange resin, the filter can be regenerated by supplying hydroxide ions (OH ⁻ ) in the form of, for example, a sodium hydroxide (NaOH) aqueous solution. In addition, for the cation exchange resin, the filter can be regenerated by supplying a sodium chloride (NaCl) aqueous solution, for example.

The filter regeneration is performed in a state where the flow of the chemical solution to the ion removal filter 525 is stopped, and residual ions are discharged by removing DIW in the ion removal filter 525 after the regeneration process. The liquid system discharged from the ion removal filter 525 during the regeneration process is discharged to the outside to avoid flowing into the pipe 505 . In addition, such a filter regeneration function can be applied to any one of the first to fourth embodiments.

The substrate processing unit 10 of the above-described first to fifth embodiments is a so-called blade-type substrate processing apparatus. This substrate processing apparatus accommodates the substrates S to be processed one by one in the processing chamber 11 and processes them. . However, the structure of the substrate processing apparatus to which the present invention is applied is not limited to this. For example, the present invention can also be applied to a so-called batch-type substrate processing apparatus that processes a plurality of substrates simultaneously as shown below.

FIG. 10A is a diagram showing the schematic structure of a sixth embodiment of the substrate processing apparatus of the present invention. In addition, FIG. 10B is a diagram showing the schematic structure of the seventh embodiment of the substrate processing apparatus of the present invention. The substrate processing apparatus 6 of the sixth embodiment shown in FIG. 10A includes a substrate processing unit 60 and a chemical solution supply unit 600. The substrate processing unit 60 includes a processing tank 61 that can house the entire substrate S inside and store a liquid. In this substrate processing unit 60 , the etching process of the substrate S is performed by immersing the substrate S in the chemical solution CS stored in the processing tank 61 . In this case, by using the ability to simultaneously The processing tank having a volume accommodating a plurality of substrates S enables execution of so-called batch processing in which a plurality of substrates are processed simultaneously.

The chemical solution supply unit 600 has the same structure as the chemical solution supply unit 100 described in the first embodiment. Specifically, the chemical solution supply unit 600 includes a mixer 601, a storage tank 603, a pipe 605, a temperature regulator 611, a liquid supply pump 613, a particle filter 615, an output pipe 607, a control valve 617, and the like. These structures are as well as The functions are the same as the corresponding configurations in the first embodiment.

In addition, an ion removal filter 612 is inserted into the output piping 607 . This configuration and function are also the same as those of the ion removal filter 121 of the first embodiment. The chemical liquid that has passed the ion removal filter 621 is supplied into the treatment tank 61 from the lower part of the treatment tank 61 . In this way, the substrate S is immersed in the processing tank 61 and the processing tank 61 is filled with a fresh chemical solution with an appropriate ion concentration, thereby performing the etching process. The chemical solution overflowing from the upper part of the treatment tank 61 is discharged to the outside.

In the substrate processing apparatus 7 of the seventh embodiment shown in FIG. 10B , the structure of the chemical supply unit 700 is different from that of the sixth embodiment. The chemical solution supply unit 700 in the seventh embodiment has the same configuration as the chemical solution supply unit 300 in the third embodiment. That is, the chemical solution supply unit 700 of this embodiment includes a mixer 701, a storage tank 703, a pipe 705, pipes 705a and 705b branched from the pipe 705, a temperature regulator 711, a liquid supply pump 713, a particle filter 715, Output piping 707, control valves 717, 721, 723, ion removal filter 725, concentration meter 727, and the like. These structures and functions are the same as those in the third embodiment.

With such a configuration, a chemical solution with an appropriate ion concentration can be supplied to the processing tank 61 , and the etching process of the substrate S can be performed satisfactorily. Similar to the fourth embodiment, further enhancement functions may be added.

In addition, in these embodiments, an anion removal filter and a cation removal filter may be used together like the second embodiment. In addition, like the fifth embodiment, a filter regeneration function may be added. As described above, the chemical solution supply unit shown in the first to fifth embodiments can also be combined with a substrate processing unit that performs batch processing.

As explained above, in the substrate processing apparatus of the above-described first embodiment, the mixer 101 and the storage tank 103 are integrated and function as the "chemical liquid preparation part" of the present invention, and the storage tank 103 is equivalent to the present invention. "storage container". In addition, the ion removal filter 121 functions as the "ion removal part" of the present invention. In addition, the piping 105 and the liquid supply pump 113 are integrated and function as the "chemical liquid supply part" of the present invention. In addition, the output pipe 107 corresponds to the "supply pipe" of the present invention. The configuration corresponding to the above is also the same in each embodiment after the second embodiment.

In addition, the concentration meter 327 and the like in the third, fourth, fifth and sixth embodiments function as the "concentration measuring part" of the present invention, and the control valves 321, 323 and the like function as the "concentration measuring part" of the present invention. The "concentration adjustment unit" functions. In addition, the regeneration pipe 531 and the control valves 533 and 535 in the fifth embodiment function as the "regeneration part" of the present invention.

In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made in addition to the above-described contents without departing from the gist of the present invention. For example, in the above-described first and second embodiments, an ion removal filter is provided inside the processing chamber 11 for the purpose of removing ions at a position near the nozzle 15a that finally supplies the chemical solution to the substrate S. 121 etc. This method can also be replaced by integrating the ion removal filter with the processing chamber, for example, being installed on the outer wall of the processing chamber.

In addition, for example, in each of the above embodiments, a temperature regulator and a particle filter are provided in the flow path of the chemical solution, but these are not essential requirements. In addition, in each of the above embodiments, a circulation flow path is provided. However, even in a substrate processing apparatus that is not provided with such a circulation channel, the effect of improving the etching rate in a narrow region by the ion removal of the present invention is still effective.

In addition, the types of chemical substances (etching objects, solutes, solvents, etc.) listed in the above embodiments are only examples, and the present invention can be applied to processes using various substances other than those mentioned above.

As described above, in the substrate processing apparatus of the present invention, the ion removal unit can be provided in the processing chamber, as described in the exemplary embodiment. For example, it may be installed inside the processing chamber. Even if a portion of the ionic species is removed from the chemical solution, the concentration of ions will still increase over time due to the shift in ionization equilibrium. By removing ions as close as possible to the position supplied to the substrate, the effect of the present invention can be made more certain.

In addition, for example, the medical solution preparation part may have a storage container that temporarily stores the prepared medical solution; the medical solution supply part may have a circulation flow path that circulates the medical solution sent from the storage container to the storage container; And an ion removal part is provided in the flow path branched from the circulation flow path. According to this configuration, the ion removal unit is provided in the flow path branched from the circulation flow path and directed toward the substrate while circulating the chemical solution in the equilibrium state in the circulation flow path. In this way, the ion concentration of the chemical solution supplied to the substrate can be reliably reduced.

On the other hand, for example, the following configuration can also be set: the medical solution preparation unit has a storage container that temporarily stores the prepared medical solution; and the medical solution supply unit has a circulation flow path that circulates the medical solution sent from the storage container. to the storage container; and the supply flow path is branched from the circulation flow path and supplies the chemical liquid to the substrate; and the circulation flow path is provided at the branch point between the storage container and the branch to the supply flow path: An ion removal unit, a concentration measurement unit that measures the concentration of ion species in the chemical solution, and a concentration adjustment unit that adjusts the ion concentration in the chemical solution based on the measurement result of the concentration measurement unit. With this configuration, the ion concentration in the chemical solution can be appropriately maintained and supplied to the substrate.

In this case, the following configuration may be provided: the concentration adjustment unit has a bypass flow path connected to the circulation flow path and bypassing the ion removal unit; and a control valve controlled based on the measurement result of the ion concentration measurement unit. The flow rate of the chemical liquid in the bypass flow path. According to such a configuration, the ratio of the chemical solution after ion removal and the chemical solution before ion removal can be changed, and the ion concentration in the chemical solution can be increased or decreased.

In addition, for example, the ion removal part may remove ion species through an ion exchange resin or an ion exchange membrane. Such well-known materials can be used to achieve the ion removal of the present invention.

In this case, you may further include a regeneration part for regenerating the ion exchange resin included in the ion removal part. By adding a function to regenerate the ion exchange resin, ion removal can be performed stably over a long period of time.

Furthermore, for example, the chemical solution preparation unit may be configured to control the amount of solute added to the chemical solution based on a measurement result of the concentration of the unionized solute in the chemical solution. By removing specific ionic species, the ionization equilibrium shifts, thereby reducing the concentration of unionized solutes in the chemical solution. Unionized solutes also contribute to the etching reaction, and a decrease in the concentration of unionized solutes causes a decrease in the etching rate. Such problems can be avoided by controlling the amount of solute in the liquid based on the concentration of the unionized solute.

Furthermore, in the substrate processing apparatus and substrate processing method of the present invention, the etched portion of the substrate to be etched can be a recessed portion with a minimum opening size of 10 nanometers or less, and more preferably 5 nanometers or less. In the manufacturing of devices such as semiconductors, in a general combination of an etching object and a chemical solution, the electric potential of the electric double layer formed on the surface of the material affects the standard Debye length of the distance, which is about a few nanometers. When the size of the opening is small to this extent, the etching rate is significantly reduced, making the present invention function particularly effectively.

In addition, in the present invention, it can be set that the chemical solution contains hydrogen fluoride as an etchant; and the ion removal unit removes dihydrogen fluoride ions. For example, when the object to be removed by etching is silicon dioxide, hydrogen fluoride is effective as an etchant. On the other hand, the chemical solution may also be configured to contain hydrogen peroxide as an etchant; the ion removal unit may remove hydrogen peroxide ions. For example, when the object to be removed by etching is titanium dioxide, hydrogen peroxide is effective as an etchant. In these cases, in a region with a large opening, even if the ions effectively function as an etchant, their contribution to the etching reaction becomes smaller in a narrow region. By removing such ionic species, the etching reaction based on the unionized etchant can be promoted.

In addition, for example, the substrate processing method of the present invention may further include: a step of measuring the ion concentration in the chemical solution that has passed through the ion removal unit; and a step of adjusting the ion concentration in the chemical solution based on the measurement results. . According to such a configuration, the ion concentration in the chemical solution can be appropriately maintained and supplied to the substrate.

The present invention has been described above based on specific embodiments, but this description is not intended to be interpreted in a limited sense. Various modifications of the disclosed embodiments will be readily apparent to those skilled in the art with reference to the description of the invention, as will other embodiments of the invention. Therefore, the patent application scope in the appendix will be understood to include such modifications or embodiments as long as they do not deviate from the true scope of the invention.

[Industrial Applicability]

The present invention can be applied to a technology for etching a substrate using a chemical solution containing an ionized solute in the liquid as an etchant. It is especially suitable for device manufacturing processes that require narrow area etching to make the opening size below 10 nanometers.

1:Substrate processing device

10:Substrate processing unit

11: Processing chamber

13:Substrate holding part

15: Liquid ejection part

15a:Nozzle

15b: Swing arm

19:Control unit

100:Substrate processing unit

101:Mixer

103:Storage tank

105:Piping

107:Output piping

111:Temperature regulator

113:Liquid delivery pump

115:Particle filter

117:Control valve

121:Ion removal filter

CS: liquid medicine

S:Substrate

Claims (18)

A substrate processing apparatus is provided with: a chemical liquid preparation unit for preparing a medical liquid, the chemical liquid containing a solute that acts as an etchant and is ionized in the liquid; and a processing chamber for accommodating a substrate, and the chemical liquid is used to prepare the substrate. The substrate is etched; the ion removal unit removes at least a part of specific ion species in the chemical solution that do not contribute to the etching of the narrow portion or hinder the etching reaction of the narrow portion; and the chemical solution supply portion is formed The flow path of the chemical solution is to supply the chemical solution sent from the chemical solution preparation part to the substrate in the processing chamber through the ion removal part. The substrate processing apparatus according to claim 1, wherein the ion removal unit is provided in the processing chamber. The substrate processing apparatus according to claim 2, wherein the ion removal unit is provided inside the processing chamber. The substrate processing apparatus according to any one of claims 1 to 3, wherein the chemical liquid preparation unit has a storage container that temporarily stores the chemical liquid before being prepared; and the chemical liquid supply unit has a circulation channel that is The chemical solution sent from the storage container is circulated to the storage container; the ion removal unit is provided in the flow path branched from the circulation flow path. The substrate processing apparatus according to any one of claims 1 to 3, wherein the chemical liquid preparation unit is provided with: a storage container for temporarily storing the prepared chemical liquid; and the chemical liquid supply unit is provided with: The circulation flow path circulates the chemical solution sent from the storage container to the storage container; and the supply flow path branches from the circulation flow path to supply the chemical solution to the substrate; it branches from the storage container to The circulation flow path to the branch point of the supply flow path is provided with: the ion removal part; a concentration measurement part that measures the concentration of the ion species in the chemical solution; and a concentration adjustment part that is based on the concentration measurement part. The ion concentration in the aforementioned chemical solution is adjusted based on the measurement results. The substrate processing apparatus according to Claim 5, wherein the concentration adjustment unit has: a bypass flow path connected to the circulation flow path and bypassing the ion removal unit; and a control valve configured according to the ion concentration measurement unit. The measurement results are used to control the flow rate of the aforementioned chemical liquid in the aforementioned bypass flow path. The substrate processing apparatus according to any one of claims 1 to 3, wherein the ion removal part removes the ion species through an ion exchange resin or an ion exchange membrane. The substrate processing apparatus according to claim 7, further comprising: a regeneration unit for regenerating the ion exchange resin included in the ion removal unit. The substrate processing apparatus according to any one of claims 1 to 3, wherein the chemical solution preparation unit controls the amount of the solute added to the chemical solution based on a measurement result of the concentration of the unionized solute in the chemical solution. quantity. The substrate processing apparatus according to any one of claims 1 to 3, wherein the chemical solution contains hydrogen fluoride ions as the etchant; The aforementioned ion removal unit removes hydrogen difluoride ions. A substrate processing method, which includes the steps of: preparing a chemical liquid, the chemical liquid containing a solute that acts as an etchant and ionizes in the liquid; sending the prepared medical liquid to an ion removal unit, and removing the chemical liquid The step of removing at least a part of specific ion species that do not contribute to the etching of the narrow portion or hinder the reaction of the etching of the narrow portion; and the step of supplying the chemical solution to the substrate to perform the etching process before passing through the ion removal portion. The substrate processing method according to claim 11, wherein the etched portion of the substrate before the etching process is a recessed portion with a minimum opening size of 10 nanometers or less. The substrate processing method according to claim 12, wherein the minimum size of the opening is 5 nanometers or less. The substrate processing method according to any one of claims 11 to 13, wherein the chemical liquid contains hydrogen fluoride as the etchant; and the ion removal unit removes dihydrogen fluoride ions. The substrate processing method according to claim 14, wherein the object to be removed by the etching process is silicon dioxide. The substrate processing method according to any one of claims 11 to 13, wherein the chemical solution contains hydrogen peroxide as an etchant; and the ion removal unit removes hydrogen peroxide ions. The substrate processing method according to Claim 16, wherein the object to be removed by the etching process is titanium dioxide. The substrate processing method according to any one of claims 11 to 13, further comprising: measuring the ion concentration in the chemical solution before passing through the ion removal part; and adjusting the chemical solution based on the result of the measurement. ion concentration in the process.