TWI872901B - Substrate processing method and substrate processing device - Google Patents

Abstract

Since the nanobubble NB+ is positively charged, the negative ions (HF ₂ ^- ) of the etching species are attracted to the nanobubble NB+ and the positive ions (H ⁺ ) of the etching species repel the nanobubble NB+. Therefore, even in a narrow recess, the active etching species of the etching liquid EF circulates continuously. In addition, even in a narrow recess, since the particle size of the nanobubble NB+ is larger than the thickness of the first layer L1, the nanobubble NB+ will not enter the recess. Therefore, the nanobubble NB+ exists outside the narrow recess where the active etching species are abundantly present, thereby helping the etching liquid EF to be stirred in the narrow recess. As a result, regardless of the size of the first layer L1 on the substrate W, the substrate W can be properly etched.

Description

Substrate processing method and substrate processing device

The present invention relates to a substrate processing method and a substrate processing device, which are used to process substrates such as semiconductor wafers, substrates for liquid crystal displays or organic EL (Electroluminescence) display devices, glass substrates for masks, substrates for optical disks, substrates for magnetic disks, ceramic substrates, and substrates for solar cells (hereinafter referred to as substrates).

Conventionally, as such a method, there is a method of supplying an etching liquid to a substrate and etching the substrate (see, for example, Patent Documents 1 and 2). [Prior Art Document] [Patent Document]

[Patent document 1] Japanese Patent Publication No. 9-22891. [Patent document 2] Japanese Patent Publication No. 9-115875.

[The problem that the invention wants to solve]

However, in the case of the conventional examples having such a structure, there are the following problems. That is, in recent years, in the pattern formed on the surface of the substrate, the type of three-dimensional structure that is miniaturized and more complex has continued to develop. Specifically, the process has progressed from fin-type FETs (field effect transistors) to gate-all-around (GAA)-type FETs (nano wires, nanosheets), nanosheets + BPRs (Buried Power Rails), forksheets + new standard cell architecture (new std cell arch), CFETs (complementary field effect transistors) + BEOL (back end of line) width/airgaps, CFET width/2D atomic channels. Therefore, etching in narrower and deeper areas is required. For example, the pattern includes multiple protrusions (structures) and multiple recesses (spaces). In addition, the pattern includes an etching target layer sandwiched by a non-etching target layer. For example, the recess and the etching target layer are small. The size of the recess and the etching target layer is sometimes less than tens of nanometers, for example.

Therefore, during the etching process, the etching liquid is sometimes supplied to the small recess and the etching target layer. However, the quality of the etching process is sometimes reduced according to the size of the recess and the etching target layer. For example, when the recess and the etching target layer are small, the substrate may not be properly etched. When the recess and the etching target layer are small, the etching function may be reduced.

The present invention was developed in view of such a situation, and its purpose is to provide a substrate processing method and a substrate processing device, which can properly etch the substrate regardless of the size of the concave portion on the substrate and the etching target layer. [Means for solving the problem]

The inventors of the present invention have made great efforts to study in order to solve the above-mentioned problems, and have obtained the following insights. Refer to Figures 9 and 10 here. Figure 9 shows the structure of the sample to be etched. Figure 10 is a graph showing the etching rate when etching is performed while imparting ultrasonic vibration. In the substrate W belonging to the sample, the first layer L1 is composed of an oxide film (SiO ₂ ). The first layer L1 is the etching object layer. In the sample, the second layer L2, which is the upper layer of the first layer L1, is composed of polycrystalline silicon. In the sample, the third layer L3, which is the lower layer of the first layer L1, is composed of silicon. The first layer L1, the second layer L2, and the third layer L3 have different components. The first layer L1 of this sample was etched. As the etching of the first layer L1 progressed, a recess was formed between the second layer L2 and the third layer L3.

In each sample, the thickness of the first layer L1 is different, such as 3nm, 5nm, and 10nm. The etching solution is a solution formed by mixing hydrofluoric acid (HF) and pure water (DIW (deionized water)). The mixing ratio is HF:DIW=1:5. Each sample of the above structure is immersed in this etching solution for one minute. The length EL of the first layer L1 etched in the direction orthogonal to the stacking direction of the first layer L1 to the third layer L3 is measured. The etching speed (nm/min) is calculated based on the measurement results. Furthermore, as a physical aid, it is compared with the case where ultrasonic vibration is given to the etching solution. Figure 10 is a graphical comparison result. According to the graph of FIG10 , the narrower the first layer L1 is, the lower the etching rate is. Furthermore, even if physical assistance is provided, the etching rate is not improved. Based on this result, the inventors of the present invention believe that the etching rate is not improved because the alternation of etching species (HF ₂ ^- , H ⁺ ) that contribute to etching in the etching solution does not occur near the narrow first layer L1. The present invention based on this view is constructed as follows.

That is, the invention described in Scheme 1 is a substrate processing method for processing a substrate; the substrate comprises: a first layer; a second layer formed on one side of the first layer and having a composition different from that of the first layer; and a third layer formed on the other side of the first layer and having a composition different from that of the first layer; the substrate processing method comprises: an etching step, wherein an etching liquid is applied to the substrate to etch the first layer; the particle size of the etching liquid is larger than the thickness of the first layer, the etching liquid comprises charged nanobubbles, and the etching liquid comprises ions or polarized molecules for etching the first layer.

[Function and Effect] According to the invention described in the first scheme, in the etching step, a recess is formed between the second layer and the third layer as the etching of the first layer proceeds. In the etching step, the charged nanobubbles are etching species that attract or repel ions of the etching liquid or polarized molecules. Therefore, the etching liquid supplied to the substrate is stirred and the active etching species are circulated. In addition, even if the recess is narrow, the charged nanobubbles will not enter the recess because the particle size of the charged nanobubbles is larger than the thickness of the first layer. Therefore, the nanobubbles exist outside the recess where the active etching species are abundantly present, thereby helping to stir the etching liquid in the narrow recess. As a result, the substrate can be properly etched regardless of the size of the recess on the substrate and the etching target layer.

The so-called nanobubbles here refer to bubbles with a particle size of several nanometers to several hundred nanometers.

In addition, in the present invention, it is preferred that a mixing step is performed before the etching step, wherein the dilute solution containing the nanobubbles is mixed with a chemical solution to generate the etching solution (Scheme 2).

Nanobubbles are easily crushed by compression, expansion, eddy current, etc. generated during the flow of the fluid. Therefore, before the etching step, the diluted solution containing nanobubbles is mixed with the chemical solution in the mixing step to generate the aforementioned etching solution. In this way, the effect of the nanobubbles can be maximized and the etching step can be performed. As a result, the substrate can be properly etched.

In addition, in the present invention, it is preferred that the mixing step is to supply the diluted solution containing the nanobubbles and the chemical solution to the vicinity of the substrate to generate the etching solution (Scheme 3).

Since the etching solution is generated by mixing the diluted solution containing nanobubbles with the chemical solution near the substrate, the etching step can be performed before the nanobubbles in the diluted solution are reduced due to compression. As a result, the effect of the nanobubbles can be maximized while the reduction of the nanobubbles is limited to a minimum.

Furthermore, in the present invention, it is preferred that the mixing step is to mix the diluted solution containing the nanobubbles and the chemical solution in a mixing tank further upstream than the position where the etching solution is supplied to the substrate (Scheme 4).

The etching solution is generated by mixing the dilute solution containing nanobubbles with the chemical solution in the mixing tank. Therefore, before the nanobubbles in the dilute solution are greatly reduced due to compression, the dilute solution and the chemical solution are fully mixed in the mixing tank, and then the etching step can be performed with the etching solution. As a result, the etching solution can be supplied without uneven mixing of the chemical solution. Therefore, uneven etching processing can be suppressed.

Furthermore, in the present invention, it is preferred that the mixing step is to mix the diluted solution containing the nanobubbles and the chemical solution in a mixing valve further upstream than the position where the etching solution is supplied to the substrate (Scheme 5).

The etching liquid is generated by mixing the diluted liquid containing nanobubbles with the chemical solution in the mixing valve. Therefore, the etching liquid can be supplied to the substrate in a short time after being generated. As a result, the etching liquid can be supplied in a state where the chemical concentration in the etching liquid is accurately adjusted to the required concentration, and the etching liquid can be supplied to the substrate in a state where the reduction of nanobubbles is limited to a minimum.

Furthermore, in the present invention, it is preferred that pure water is passed through a nanobubble generator for generating nanobubbles to generate the aforementioned dilute solution (Scheme 6).

Pure water is passed through the nanobubble generator, thereby generating nanobubbles in the pure water to produce a dilute solution. Therefore, since a large amount of the dilute solution containing nanobubbles can be used in the etching step, the etching solution can be sufficiently stirred.

In addition, in the present invention, it is preferred that the aforementioned diluent is a solution containing pre-generated nanobubbles in pure water (Scheme 7).

Since nanobubbles are generated in pure water, no time is required. Therefore, the etching step can be performed in a short time.

In addition, the present invention preferably further comprises, before the aforementioned etching step, a conditioning solution mixing step of mixing a conditioning solution for adjusting the pH (acidity and alkalinity) of the aforementioned etching solution (Scheme 8).

If the pH of the etching solution is adjusted by the solution mixing step, the zeta potential of the nanobubbles can be adjusted. Therefore, since the charge level of the nanobubbles can be adjusted, the stirring level of the etching solution can be adjusted.

In addition, in the present invention, it is preferred that the conditioning solution is a chemical solution that further enhances the acidity or alkalinity of the etching solution (Scheme 9).

When the acidity or alkalinity of the etching solution is further increased, the absolute value of the boundary potential can be increased. Therefore, the degree of charging of the nanobubbles can be increased. As a result, the degree of stirring of the etching solution can be increased.

In addition, the invention described in scheme 10 is a substrate processing device for processing a substrate; the substrate comprises: a first layer; a second layer formed on one side of the first layer and having a different composition from the first layer; and a third layer formed on the other side of the first layer and having a different composition from the first layer; the substrate processing device comprises: a processing unit for processing the substrate; board; a supply unit, which supplies an etching liquid to the processing unit, wherein the particle size of the etching liquid is larger than the thickness of the first layer, the etching liquid contains charged nanobubbles, and the etching liquid contains ions or polarized molecules for etching the first layer; and a control unit, which allows the etching liquid supplied from the supply unit to act on the substrate held by the holding unit to etch the first layer.

[Function and Effect] According to the invention described in the tenth scheme, the control unit supplies the etching liquid from the supply unit to the substrate of the processing unit. As the etching of the first layer proceeds, a recess is formed between the second layer and the third layer. In the etching liquid, the charged nanobubbles are etching species that attract or repel ions of the etching liquid or polarized molecules. Therefore, the etching liquid supplied to the substrate is stirred and the active etching species are circulated to the substrate. In addition, even if the recess is narrow, since the particle size of the charged nanobubbles is larger than the thickness of the first layer, the nanobubbles will not enter the recess. Therefore, nanobubbles exist outside the concave part where active etching species are abundant, thereby helping to stir the etching liquid in the narrow concave part. As a result, the substrate can be properly etched regardless of the size of the concave part on the substrate and the etching target layer. [Effect of the invention]

According to the substrate processing method of the present invention, in the etching step, a recess is formed between the second layer and the third layer as the etching of the first layer proceeds. In the etching step, the charged nanobubbles attract or repel the ions of the etching liquid or the polarized molecular etching species. Therefore, the etching liquid supplied to the substrate is stirred and the active etching species are circulated. In addition, even if the recess is narrow, the charged nanobubbles will not enter the recess because the particle size of the charged nanobubbles is larger than the thickness of the first layer. Therefore, the nanobubbles exist outside the recess where the active etching species are abundantly present, thereby helping the etching liquid to be stirred in the narrow recess. As a result, the substrate can be properly etched regardless of the size of the recess on the substrate and the etching target layer.

The present invention is described below with examples. [Example 1]

The following describes the first embodiment of the present invention with reference to the drawings.

Fig. 1 is a block diagram showing a schematic structure of a substrate processing apparatus according to the first embodiment. Fig. 2 is a schematic diagram illustrating the effect of a nano-bubble having a positive potential. Fig. 3 is a schematic diagram illustrating the effect of a nano-bubble having a negative potential.

[1-1. Configuration of the device]

The substrate processing device 1 processes a substrate W. The substrate W is, for example, circular in a plan view. The substrate W is, for example, a thin plate. The substrate W is, for example, made of a semiconductor. The substrate W is, for example, silicon.

The substrate processing device 1 performs a predetermined process on the substrate W. The substrate processing device 1 is a blade-type device that processes the substrates W one by one in sequence. The substrate processing device 1 performs, for example, an etching process on the substrate W. The etching process is chemical etching of various films formed on the substrate W. The etching process is processing the shapes of various films formed on the substrate W. The etching process is performed by an etching step.

The substrate processing apparatus 1 includes a processing unit 3 , a supply unit 5 , and a control unit 7 .

The processing section 3 accommodates the substrate W. The processing section 3 processes the substrate W. The processing section 3 includes a chuck 9, a rotation shaft 11, an electric motor 13, and a guard 15.

The clamp 9 holds the substrate W in a horizontal position. The clamp 9, for example, adsorbs and holds the central portion of the lower surface of the substrate W. The clamp 9 abuts and supports the substrate W at the upper surface. The clamp 9 is smaller than the diameter of the substrate W. The rotating shaft 11 is cylindrical. The rotating shaft 11 extends in the vertical direction. The lower surface of the clamp 9 is mounted at the upper end of the rotating shaft 11. The lower end of the rotating shaft 11 is connected to the electric motor 13. The electric motor 13 rotates the rotating shaft 11 around the axis P1. The electric motor 13 rotates the substrate W around the axis P1 together with the rotating shaft 11 and the clamp 9. A protective cover 15 is arranged on the outer peripheral side of the clamp 9. The shield 15 prevents the processing liquid supplied to the substrate W from scattering around. The shield 15 moves up and down between a standby position where the upper end is lower than the jig 9 and a processing position where the upper end is higher than the jig 9 .

The clamp 9 may be a so-called mechanical clamp that abuts against and supports the outer periphery of the substrate W. The mechanical clamp 9 has an outer diameter slightly larger than the outer diameter of the substrate W.

The supply unit 5 includes a first nozzle 17, a second nozzle 19, a first supply pipe 21, a second supply pipe 23, a first supply tank 25, and a second supply tank 27. The first nozzle 17 and the second nozzle 19 are configured to be movable across a supply position and a standby position. The supply position is used to supply the processing liquid to the position where the shaft core P1 intersects with the upper surface of the substrate W, and the standby position is a position away from the side of the protective cover 15. The first nozzle 17 and the second nozzle 19 supply the processing liquid to the upper surface of the substrate W at the supply position. The supply position is located above the substrate W. The standby position is a position away from the side of the substrate W.

In the first supply pipe 21, the first nozzle 17 is connected to one end of the first supply pipe 21. In the first supply pipe 21, the first supply tank 25 is connected to the other end of the first supply pipe 21. The first supply tank 25 stores the first treatment liquid. The first supply pipe 21 is provided with a control valve 29, a pump 31 and a flowmeter 33 from the first supply tank 25 toward the first nozzle 17. The control valve 29 adjusts the flow of the first treatment liquid in the first supply pipe 21. The control valve 29 is switched to block the flow of the first treatment liquid or to allow the first treatment liquid to flow at a set flow rate. The pump 31 supplies the first treatment liquid stored in the first supply tank 25 to the first nozzle 17 via the first supply pipe 21. The flow of the first treatment liquid at this time depends on the setting of the control valve 29. The flow meter 33 detects the flow rate of the first processing liquid.

The first processing liquid is, for example, pure water (DIW). The first processing liquid contains nanobubbles in pure water. Nanobubbles are bubbles with a particle size of several nm to several hundred nm. The particle size of the nanobubbles is larger than the size of the etching target layer and the concave portion. The first processing liquid is nanobubble water. The first processing liquid is, for example, commercially available nanobubble water, which contains nanobubbles of the above-mentioned particle size. The first processing liquid is, for example, stored in the first supply tank 25 after the nanobubble water containing nanobubbles of the above-mentioned particle size is generated.

The first processing liquid is equivalent to the "diluted liquid" in the present invention.

In the second supply pipe 23, the second nozzle 19 is connected to one end of the second supply pipe 23. In the second supply pipe 23, the second supply tank 27 is connected to the other end of the second supply pipe 23. The second supply tank 27 stores the second treatment liquid. The second supply pipe 23 is provided with a control valve 35, a pump 37 and a flow meter 39 from the second supply tank 27 toward the second nozzle 19. The control valve 35 adjusts the flow of the second treatment liquid in the second supply pipe 23. The control valve 35 is switched to block the flow of the second treatment liquid or to allow the second treatment liquid to flow at a set flow rate. The pump 37 supplies the second treatment liquid stored in the second supply tank 27 to the second nozzle 19 via the second supply pipe 23. The flow of the second treatment liquid at this time depends on the setting of the control valve 35. The flow meter 39 detects the flow rate of the second processing liquid.

The second treatment liquid is different from the first treatment liquid. The second treatment liquid is a chemical liquid. The chemical liquid is, for example, hydrofluoric acid (HF).

The first processing liquid and the second processing liquid are mixed to form an etching liquid. The mixing ratio of the first processing liquid supplied by the first nozzle 17 and the second processing liquid supplied by the second nozzle 19 is, for example, 5:1. This ratio is adjusted according to the etching target layer in the substrate W and the required etching speed in the concave portion.

The control unit 7 controls the above-mentioned units in general. The control unit 7 is equipped with a CPU (Central Processing Unit) and a memory which are not shown in the figure. The memory stores a control program and a recipe in advance, and the recipe specifies the conditions for processing the substrate W, etc. The control unit 7 controls the movement of the first nozzle 17 and the movement of the second nozzle 19. The control unit 7 controls the lifting and lowering of the protective cover 15. The control unit 7 operates the control valves 29 and 35 and controls the flow rate of the first processing liquid in the first supply pipe 21 and the flow rate of the second processing liquid in the second supply pipe 23. The control unit 7 receives the flow rate detected by the flow meters 33 and 39. The control unit 7 can operate the control valves 29 and 35 and perform feedback control on the flow rate of the first processing liquid and the flow rate of the second processing liquid.

[1-2. Processing steps]

An example of a specific processing step of etching the substrate W performed by the substrate processing apparatus 1 will be described.

The substrate W on which the film to be processed is formed is placed on the jig 9. The substrate W is transported by a transport arm (not shown). The substrate W is adsorbed on the jig 9. The substrate W has an etching target layer formed on its upper surface.

The control unit 7 raises the protective cover 15 to the processing position. The control unit 7 moves the first nozzle 17 and the second nozzle 19 to the supply position. The control unit 7 operates the electric motor 13 and rotates the substrate W at the processing speed according to the prescription. The processing speed is lower than the drying speed described later. The processing speed is, for example, several hundred rpm. The control unit 7 operates the control valves 29, 35 and the pumps 31, 37 to circulate the first processing liquid and the second processing liquid in a predetermined ratio. At this time, the control valves 29, 35 can also be operated based on the detection results of the flow meters 33, 39 and feedback control can be performed.

In this way, the first processing liquid and the second processing liquid are supplied to the vicinity of the rotation center of the substrate W. The first processing liquid and the second processing liquid are supplied to the substrate W in a predetermined ratio and mixed, thereby generating an etching liquid on the upper surface of the substrate W. The control unit 7 maintains this state according to the prescription for the etching time. The etching time is, for example, several tens of minutes. Since the rotation speed of the substrate W is relatively low, the etching liquid is retained on the upper surface of the substrate W with a sufficient thickness, and the etching liquid is discharged from the outer periphery to the surroundings. Thereby, the etching object layer formed on the surface of the substrate W is etched. The etching step performed by the etching liquid is implemented.

The step of supplying the first processing liquid and the second processing liquid to the substrate W and mixing them is equivalent to the "mixing step" of the present invention. The step of supplying the first processing liquid and the second processing liquid to the substrate W in a predetermined ratio and allowing the etching liquid to act on the substrate W is equivalent to the "etching step" of the present invention.

The control unit 7 closes the control valves 29 and 35 after the etching time has passed. The control unit 7 stops the pumps 31 and 37 after the etching time has passed. The control unit 7 moves the first nozzle 17 and the second nozzle 19 to the standby position. The control unit 7 moves the unillustrated nozzle to the axis P1 of the substrate W and supplies the cleaning liquid to the unillustrated nozzle. The cleaning liquid is, for example, pure water. Thereby, the etching liquid attached to the upper surface of the substrate W is washed away. The cleaning step performed by the cleaning liquid is implemented.

The control unit 7 stops supplying the cleaning liquid from the unillustrated nozzle after the cleaning time corresponding to the prescription has passed. The control unit 7 increases the speed of the electric motor 13 to the drying speed according to the prescription after the unillustrated nozzle is withdrawn. The drying speed is higher than the processing speed. The drying speed is, for example, several thousand rpm. This drying speed is maintained throughout the drying time corresponding to the prescription. In this way, the substrate W is subjected to a shake-off drying step. The shake-off drying step is performed.

The control unit 7 stops the electric motor 13 after drying for the drying time. The rotation of the substrate W is thereby stopped. The control unit 7 lowers the protective cover 15 to the standby position and releases the suction by the clamp 9. The control unit 7 carries out the substrate W by a transfer arm (not shown).

Through the above series of processes, the etching process of a substrate W is completed.

Here, please refer to Figures 2 and 3. Figure 2 is a schematic diagram illustrating the effect of a nanobubble with a positive potential. Figure 3 is a schematic diagram illustrating the effect of a nanobubble with a negative potential.

In the above etching step, an etching liquid is generated on the upper surface of the substrate W. The etching liquid is a mixture of pure water that belongs to the first treatment liquid and contains nanobubbles and hydrofluoric acid that belongs to the second treatment liquid. The etching liquid is acidic. In the etching liquid, when the etching target layer is an oxide film (SiO ₂ ), the etching species that contribute to etching are HF ₂ ^- , H ⁺ , and H ₂ F ₂ . Therefore, since HF ₂ ^- and H ⁺ among these etching species circulate successively to the etching target layer, the active etching species that do not act on the etching target layer act on the etching target layer, thereby suppressing the reduction of the etching rate. If the etching target layer is narrow, it is difficult for active etching species to circulate to the etching target layer. In particular, when the etching target layer is a concave portion or the etching target layer becomes a concave portion as etching progresses, the etching rate is likely to decrease.

[1-3. Special effects]

In this embodiment, nanobubble water is mixed in the etching liquid. In addition, the etching liquid is acidic. Nanobubbles are dispersed in the acidic etching liquid. Therefore, in the etching liquid in this case, the boundary potential of nanobubbles becomes positive. Nanobubbles in the etching liquid are positively charged. Nanobubbles in the etching liquid become positive electrodes. Since nanobubbles are charged with the same polarity, nanobubbles do not condense but can be dispersed in the etching liquid. As shown in FIG. 2, if the first layer L1 is sandwiched by the second layer L2 and the third layer L3 and is narrow, the etching speed is reduced.

In the first embodiment, the etching liquid EF is acidic. Therefore, since the nanobubbles NB+ are positively charged, the negative ions (HF ₂ ^- ) of the etching species are attracted by the nanobubbles NB+ and the positive ions (H ⁺ ) of the etching species repel the nanobubbles NB+. Therefore, even in a narrow recess, the active etching species of the etching liquid EF circulates continuously. In addition, even in a narrow recess, since the particle size of the nanobubbles NB+ is larger than the thickness of the first layer L1, the nanobubbles NB+ will not enter the recess. Therefore, the nanobubbles NB+ exist outside the narrow recess where the active etching species exist abundantly, thereby helping the etching liquid EF to be stirred in the narrow recess. As a result, regardless of the size of the first layer L1 on the substrate W, the substrate W can be properly etched.

In the above example, the etching solution EF is acidic. On the other hand, when the etching solution EF is SC1 (Standard Clean 1; the first standard cleaning solution; that is, ammonia-hydrogen peroxide mixture) and is alkaline, it acts as shown in FIG. 3. That is, when the etching solution EF is alkaline, the nanobubble NB- is negatively charged. Therefore, the negative ions (HO ₂ ^- , OH ^- ) of the etching species repel the nanobubble NB- and the positive ions (H ⁺ ) of the etching species are attracted to the nanobubble NB-. Therefore, similarly to the above, the active etching species of the etching solution EF circulates continuously. As a result, regardless of the size of the first layer L1 on the substrate W, the substrate W can be properly etched.

In the present invention, the ions of the etching species are stirred by charged nanobubbles. That is, the ions of the etching species are moved by charged nanobubbles instead of forming an electric field. Therefore, no electricity is required to form an electric field, and compared with a structure in which an electric field is formed to move the ions of the etching species and nanobubbles, power saving can be achieved. [Example 2]

The second embodiment of the present invention is described below with reference to the drawings. FIG. 4 is a block diagram showing the schematic structure of the substrate processing device of the second embodiment.

[2-1. Configuration of the device]

The same components as those of the above-described embodiment are denoted by the same reference numerals and detailed description thereof will be omitted. The substrate processing apparatus 1A includes a processing unit 3 , a supply unit 5A, and a control unit 7 .

The supply section 5A is provided with a third nozzle 17A. The third nozzle 17A is connected to one end of the third supply pipe 41. The other end of the third supply pipe 41 is connected to the mixing tank 43. The third supply pipe 41 is provided with a control valve 45, a pump 47 and a flow meter 49 in sequence from the mixing tank 43 side toward the third nozzle 17A side. The third nozzle 17A is configured to be movable across a supply position and a standby position, the supply position being a position corresponding to the top of the shaft core P1, and the standby position being a position away from the side of the protective cover 15. The supply position is located above the substrate W. The standby position is away from the side of the substrate W.

The control valve 45 adjusts the flow rate of the third treatment liquid in the third supply pipe 41. The control valve 45 is switched to block the flow of the third treatment liquid or allow the third treatment liquid to flow at a set flow rate. The pump 47 supplies the third treatment liquid stored in the mixing tank 43 to the third nozzle 17A through the third supply pipe 41. The flow rate of the third treatment liquid at this time depends on the setting of the control valve 45. The flow rate of the third treatment liquid at this time is detected by the flow meter 49.

The third processing liquid is a mixture of a dilute solution containing nanobubbles and a chemical solution. The mixed liquid is an etching liquid. The etching liquid is generated in a mixing tank 43. The mixing tank 43 is connected to a first supply pipe 21A and a second supply pipe 23A. One end of the first supply pipe 21A is connected to a pure water supply source. The other end of the first supply pipe 21A is connected to the mixing tank 43. The first supply pipe 21A is equipped with a control valve 29, a pump 31, a flow meter 33 and a nanobubble generator 51 in sequence from the pure water supply source side.

The nanobubble generator 51 is supplied with gas by a gas supply source. The gas is, for example, an inert gas. The inert gas is, for example, nitrogen. The nanobubble generator 51 generates nanobubbles in the first processing liquid flowing through the first supply pipe 21A. The nanobubble generator 51 mixes nanobubbles in the first processing liquid flowing through the first supply pipe 21A. The nanobubbles contain the gas supplied by the gas supply source. The second supply pipe 23A generates nanobubbles in the first processing liquid and supplies it to the mixing tank 43. The first processing liquid is, for example, pure water (DIW). The first processing liquid contains nanobubbles in pure water.

One end of the second supply pipe 23A is connected to the second supply tank 27. The other end of the second supply pipe 23A is connected to the mixing tank 43. The second supply pipe 23A is equipped with a control valve 35, a pump 37 and a flow meter 39. The second supply pipe 23A supplies the second treatment liquid to the mixing tank 43. The second treatment liquid is different from the first treatment liquid. The second treatment liquid is a chemical liquid. The chemical liquid is, for example, hydrofluoric acid (HF).

The control unit 7 operates the flow rate of the first processing liquid in the first supply pipe 21A and the flow rate of the second processing liquid in the second supply pipe 23A and generates a third processing liquid belonging to the mixed liquid in the mixing tank 43. The first processing liquid is nanobubble water. The second processing liquid is a chemical solution. The third processing liquid is an etching liquid. The control unit 7 mixes the first processing liquid and the second processing liquid in the mixing tank 43, for example, in a mixing ratio of 5:1. This ratio is adjusted according to the required etching speed in the etching object layer in the substrate W. The control unit 7 stops supplying the first processing liquid and the second processing liquid when the liquid level of the third processing liquid stored in the mixing tank 43 reaches a predetermined height.

The step of mixing the first treatment liquid and the second treatment liquid in the mixing tank 43 is equivalent to the “mixing step” in the present invention.

The mixing tank 43 is preferably equipped with a liquid level sensor. In this case, the control unit 7 replenishes the first processing liquid and the second processing liquid from the first supply pipe 21A and the second supply pipe 23A when the detection position of the liquid level sensor is lower than the predetermined position. The predetermined position is a position corresponding to the amount of etching liquid required for at least one etching process. In this way, the following state is maintained: the amount of etching liquid required for one etching process can be supplied at any time.

[2-2. Processing steps]

An example of a specific processing step for etching the substrate W performed by the substrate processing apparatus 1A will be described.

The operations of transferring the substrate W to the processing section 3 and rotating the substrate W are the same as those in the above-described embodiment.

The control unit 7 pre-generates an etching liquid of a predetermined concentration in the mixing tank 43. The control unit 7 moves the third nozzle 17A to the supply position. The control unit 7 operates the control valve 45 and the pump 47 while the substrate W is rotated at the processing speed, and supplies the third processing liquid from the third nozzle 17A to the rotation center of the substrate W. That is, the third processing liquid is supplied to the vicinity of the axis core P1.

After the etching time has passed, the control unit 7 closes the control valve 45 and stops the pump 47. Thereafter, the cleaning step and the drying step are sequentially performed in the same manner as in the embodiment. Through these processes, the etching process for one substrate W is completed.

According to the second embodiment, the same effect as the above embodiment is exerted. That is, the nanobubbles exist outside the narrow concave part where the active etching species are abundantly present, thereby helping the etching liquid to stir in the narrow concave part. As a result, the substrate W can be properly etched regardless of the size of the first layer L1 on the substrate W. In addition, in the second embodiment, the dilute liquid containing nanobubbles and the chemical solution are mixed in the mixing tank 43 to generate the etching liquid. Therefore, before the nanobubbles in the dilute liquid are greatly reduced due to compression, the dilute liquid and the chemical solution are fully mixed in the mixing tank 43, and the etching step can be performed by the etching liquid. As a result, the etching liquid can be supplied without uneven mixing of the chemical solution. Therefore, uneven etching treatment can be suppressed. [Implementation Example 3]

Next, the third embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a block diagram showing the schematic structure of the substrate processing device of the third embodiment.

[3-1. Configuration of the device]

The same components as those of the above-described embodiment are denoted by the same reference numerals and detailed description thereof will be omitted. The substrate processing apparatus 1B includes a processing unit 3 , a supply unit 5B, and a control unit 7 .

The supply section 5B is provided with a fourth nozzle 17B. The fourth nozzle 17B is communicatively connected to one end of the first supply tube 21B. The other end of the first supply tube 21B is communicatively connected to the first supply tank 25. The first supply tube 21B is provided with a control valve 29, a pump 31, a flow meter 33 and a mixing valve 53 in sequence from the first supply tank 25 side toward the fourth nozzle 17B side. The first supply tank 25 stores the first processing liquid. The fourth nozzle 17B is movable to a supply position and a standby position, the supply position being a position corresponding to the top of the shaft core P1, and the standby position being a position away from the side of the protective cover 15. The supply position is located above the substrate W. The standby position is away from the side of the substrate W. The first processing liquid is, for example, pure water (DIW). The first processing liquid contains nanobubbles in pure water.

The mixing valve 53 has a secondary flow path connected to the main flow path. The mixing valve 53 has a secondary flow path connected in a direction orthogonal to the main flow path. The mixing valve 53 mixes the fluid in the main flow path with the fluid from the secondary flow path. The main flow path in the mixing valve 53 is the first supply pipe 21B.

One end of the second supply pipe 23B is connected to the secondary flow path of the mixing valve 53. The other end of the second supply pipe 23B is connected to the second supply tank 27. The second supply tank 27 stores the second treatment liquid. The second treatment liquid is different from the first treatment liquid. The second treatment liquid is a chemical liquid. The chemical liquid is, for example, hydrofluoric acid (HF).

The control unit 7 adjusts the ratio of the flow rate of the first processing liquid in the first supply pipe 21B to the flow rate of the second processing liquid in the second supply pipe 23B according to the prescription. That is, the control unit 7 adjusts the mixing ratio of the first processing liquid and the second processing liquid according to the concentration of the etching liquid specified in the prescription. Specifically, the control unit 7 adjusts the control valves 29 and 35 to adjust the concentration of the chemical solution in the etching liquid supplied by the fourth nozzle 17B.

[3-2. Processing steps]

An example of a specific processing step for etching the substrate W performed by the substrate processing apparatus 1B will be described.

The operations of transferring the substrate W to the processing section 3 and rotating the substrate W are the same as those in the above-described embodiment.

The control unit 7 mixes the first processing liquid with the second processing liquid in the mixing valve 53 to generate an etching liquid. The generated etching liquid is supplied to the substrate W from the fourth nozzle 17B. The control unit 7 closes the control valves 29 and 35 and stops the pumps 31 and 37 at a time point when the etching time has passed. Thereafter, the cleaning step and the drying step are sequentially performed in the same manner as in the embodiment. Through these processes, one substrate W is processed.

According to the third embodiment, the same effect as the above embodiment is exerted. That is, the nanobubbles exist outside the narrow concave part where the active etching species are abundantly present, thereby helping the etching liquid to be stirred in the narrow concave part. As a result, the substrate W can be properly etched regardless of the size of the first layer L1 on the substrate W. In addition, in the third embodiment, the diluent containing nanobubbles and the chemical solution are mixed in the mixing valve 53 to generate the etching liquid. Therefore, the diluent and the chemical solution can be mixed in the correct ratio. Therefore, the etching liquid can be supplied to the substrate W in a short time after being generated. As a result, the etching liquid can be supplied in a state where the concentration of the chemical solution in the etching liquid is accurately adjusted to a desired concentration, and the etching liquid can be supplied to the substrate W in a state where the reduction of nanobubbles is minimized.

[Example of variation]

The modification example will be described with reference to Fig. 6 and Fig. 7. Fig. 6 is a block diagram showing a schematic configuration of a substrate processing apparatus according to the modification example. Fig. 7 is a graph showing an example of the relationship between the Zheda potential and the pH.

This modification is a substrate processing device 1C, which is a modification of a part of the substrate processing device 1 of the first embodiment. The supply portion 5C has a first supply pipe 21, a second supply pipe 23, and an injection pipe 61. The second supply pipe 23 has a branching portion 63. One end of the injection pipe 61 is connected to the branching portion 63. The other end of the injection pipe 61 is connected to the adjustment liquid tank 65. The injection pipe 61 is provided with a control valve 67, a pump 69, and a flow meter 71 in order from the adjustment liquid tank 65 side.

The adjusting liquid tank 65 is used to store the adjusting liquid. The adjusting liquid is used to adjust the pH of the drug solution. The adjusting liquid is acidic or alkaline. The adjusting liquid is strongly acidic or strongly alkaline. The adjusting liquid is used to further enhance the acidity or alkalinity of the drug solution.

The conditioning liquid is a conditioning liquid that increases acidity, such as hydrochloric acid and sulfuric acid. In addition, the conditioning liquid is a conditioning liquid that increases alkalinity, such as sodium hydroxide and potassium hydroxide.

The control unit 7 mixes the conditioning liquid from the branching portion 63 with the second supply pipe 23. This is equivalent to the "conditioning liquid mixing step" in the present invention. The control unit 7 mixes the conditioning liquid in a manner that further enhances the acidity or alkalinity of the liquid in the second supply pipe 23. The second treatment liquid with pH adjusted in this way is supplied to the substrate W from the second nozzle 19. Therefore, it is mixed with the first treatment liquid containing nanobubbles supplied by the first nozzle 17 on the substrate W, and the substrate W is etched.

Refer to Figure 7. As can be seen from Figure 7, in a certain solution, the stronger the alkalinity, the greater the Zed potential is toward the negative side. On the other hand, the stronger the acidity, the greater the Zed potential is toward the positive side. In other words, if the pH of the etching solution is adjusted, the absolute value of the Zed potential of the nanobubbles can be increased. Therefore, since the degree of charge of the nanobubbles can be increased by mixing the adjustment solution, the degree of stirring of the etching solution can be increased.

In addition, a nozzle may be further added to mix the first processing liquid, the second processing liquid and the conditioning liquid on the substrate W to generate an etching liquid with enhanced charging of nanobubbles. In the second embodiment, the conditioning liquid may be added to the mixing tank 43. In the third embodiment, the conditioning liquid may be injected into the mixing valve 53.

[Experimental results of the present invention]

Refer to Figure 8 here. Figure 8 is a graph showing the experimental results of the present invention. In detail, the etching speed when there are no nanobubbles and when there are nanobubbles, and the etching speed due to the difference in the particle size of the nanobubbles are shown. The size of the first layer L1 is 5nm and 10nm. The etching solution is a solution composed of a mixture of hydrofluoric acid (HF) and pure water (DIW). The mixing ratio is HF:DIW=1:5. The horizontal axis shows the type of gas contained in the nanobubbles. DIW shows the etching solution that does not contain nanobubbles. The plain film ratio (or blanket ratio) is the ratio of the etching speed of the non-narrow etching target layer and the narrow etching target layer. That is, the closer the total surface film ratio (or coating ratio) is to 1, the better. For small particles, the particle size of nanobubbles is 3nm to 5nm. For large particles, the particle size of nanobubbles is tens of nm. That is, large-diameter nanobubbles will not enter the concave part.

From this result, it can be seen that the same effect cannot be obtained by only including nanobubbles in the etching solution. In other words, the particle size of the nanobubbles contained in the etching solution needs to be larger than the size of the etching target layer. In this way, even if the etching target layer is small, the etching speed is improved compared with the past.

The present invention is not limited to the above-mentioned embodiments and can be implemented in various modified forms as described below.

(1) In the above-mentioned embodiments 1 to 3, the blade-type substrate processing apparatus 1 to 1C are used as examples for explanation. However, the present invention is not limited to this form. The present invention can be applied to, for example, a batch-type substrate processing apparatus that simultaneously immerses a plurality of substrates W in a processing liquid for processing.

(2) In the above-mentioned embodiments 1 to 3, the following cases are used as examples for explanation: the chemical liquid contained in the etching solution is hydrofluoric acid (HF), the etching species of the etching solution are HF ₂ ^- and H ⁺ , and the first layer L1, which is the etching target layer, is an oxide film (SiO ₂ ). However, the present invention is not limited to these cases. In the present invention, for example, the chemical liquid, the etching target layer, and the etching species may also be the following cases.

(a) When the chemical solution is hydrofluoric acid (HF), the target layer is silicon nitride (SiN); the etching species are HF ₂ ^- , H ⁺ , F ^- , and HF. (b) When the chemical solution is hydrogen peroxide (H ₂ O ₂ ), the target layer is titanium nitride (TiN); the etching species are HO ₂ ^- , H ⁺ , and OH ^- . (c) When the chemical solution is SC1 (a mixture of DIW, NH ₄ OH, and H ₂ O ₂ ), the target layer is titanium nitride (TiN); the etching species are HO ₂ ^- , H ⁺ , and OH ^- . (d) When the chemical solution is SC2 (a mixture of DIW, HCl, and H ₂ O ₂ ), the target layer is titanium nitride (TiN); the etching species are HO ₂ ^- , H ⁺ , and OH ^- . (e) When the chemical solution is phosphoric acid (H ₃ PO ₄ ), the target layer is silicon nitride (SiN); the etching species are H ⁺ , H ₂ PO ₄ ^- , HPO ₄ ^2- , and PO ₄ ^3- .

(3) In the above-mentioned embodiments 1 to 3, the morphology of ions of the etched species is described by stirring with charged nanobubbles. However, the present invention is not limited to such a morphology. For example, the morphology of polarized molecules of the etched species can also be applied by stirring with charged nanobubbles.

(4) In each of the above-mentioned embodiments 1 to 3, a substrate W having a second layer L2 on one side of a first layer L1 and a third layer L3 on the other side of the first layer L1 is used as an example for explanation. However, the present invention is not limited to a substrate W having such a structure. That is, the present invention can be applied even to the following substrate W: the first layer L1, which is another layer to be etched, is further stacked on the second layer L2 and the third layer L3. [Industrial Applicability]

As described above, the present invention is applicable to a substrate processing method and a substrate processing apparatus for processing a substrate.

1,1A~1C: substrate processing device 3: processing unit 5,5A~5C: supply unit 7: control unit 9: fixture 11: rotating shaft 13: electric motor 15: protective cover 17: first nozzle 17A: third nozzle 17B: fourth nozzle 19: second nozzle 21,21A,21B: first supply pipe 23,23A,23B: second supply pipe 25: first supply tank 27: second supply tank 29,35,45,67: control valve 31,37,47,69: pump 33,39,49,71: flow meter 41: third supply pipe 43: mixing tank 51: nano bubble generator 53: Mixing valve 61: Injection pipe 63: Branching part 65: Adjustment tank EF: Etching liquid EL: Etched length L1: First layer L2: Second layer L3: Third layer NB+, NB-: Nanobubble P1: Axis core W: Substrate

[FIG. 1] is a block diagram showing the schematic structure of the substrate processing device of the first embodiment. [FIG. 2] is a schematic diagram illustrating the effect of nanobubbles with a positive zed potential. [FIG. 3] is a schematic diagram illustrating the effect of nanobubbles with a negative zed potential. [FIG. 4] is a block diagram showing the schematic structure of the substrate processing device of the second embodiment. [FIG. 5] is a block diagram showing the schematic structure of the substrate processing device of the third embodiment. [FIG. 6] is a block diagram showing the schematic structure of the substrate processing device of the variation. [FIG. 7] is a graph showing an example of the relationship between the zed potential and pH. [FIG. 8] is a graph showing the experimental results of the present invention. [Figure 9] is a diagram showing the structure of a sample being etched, used to explain the conventional technology. [Figure 10] is a graph showing the etching speed when etching is performed by applying ultrasonic vibration, used to explain the conventional technology.

EF: Etching liquid L1: First layer L2: Second layer L3: Third layer NB+: Nanobubbles W: Substrate

Claims (10)

A substrate processing method is used to process a substrate; the substrate comprises: a first layer; a second layer formed on one side of the first layer and having a different composition from the first layer; and a third layer formed on the other side of the first layer and having a different composition from the first layer; the substrate processing method comprises: an etching step, wherein an etching liquid is applied to the substrate to etch the first layer; the particle size of the etching liquid is larger than the thickness of the first layer, the etching liquid comprises charged nanobubbles, and the etching liquid comprises ions or polarized molecules for etching the first layer. The substrate processing method as recited in claim 1, wherein a mixing step is performed before the etching step, wherein the diluted solution containing the nanobubbles is mixed with a chemical solution to generate the etching solution. The substrate processing method as recited in claim 2, wherein the mixing step is to supply the diluted solution containing the nanobubbles and the chemical solution to the vicinity of the substrate, thereby generating the etching solution. The substrate processing method as recited in claim 2, wherein the mixing step is to mix the diluted solution containing the nanobubbles and the chemical solution in a mixing tank upstream of the position where the etching solution is supplied to the substrate. The substrate processing method as recited in claim 2, wherein the mixing step is to mix the diluted solution containing the nanobubbles and the chemical solution in a mixing valve further upstream than the position where the etching solution is supplied to the substrate. In the substrate processing method as recited in any one of claims 2 to 5, the dilute solution is generated by flowing pure water through a nanobubble generator for generating nanobubbles. The substrate processing method as recited in any one of claims 2 to 5, wherein the aforementioned diluent is a solution containing pre-generated nanobubbles in pure water. The substrate processing method as recited in any one of claims 1 to 5 further comprises, before the aforementioned etching step, a conditioning liquid mixing step of mixing a conditioning liquid for adjusting the pH of the aforementioned etching liquid. The substrate processing method as described in claim 8, wherein the conditioning solution is a chemical solution that further enhances the acidity or alkalinity of the etching solution. A substrate processing device is used to process a substrate; the substrate comprises: a first layer; a second layer formed on one side of the first layer and having a different composition from the first layer; and a third layer formed on the other side of the first layer and having a different composition from the first layer; the substrate processing device comprises: a processing unit for processing the substrate; a supply unit for supplying an etching liquid to the processing unit, the particle size of the etching liquid being larger than the thickness of the first layer, the etching liquid comprising charged nanobubbles, and the etching liquid comprising ions or polarized molecules for etching the first layer; and The control unit allows the etching liquid supplied from the supply unit to act on the substrate held by the holding unit to etch the first layer.