Patent Application
20240035168
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2022-119411, filed on Jul. 27, 2022, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a substrate processing apparatus and a substrate processing method.
The substrate processing apparatus disclosed in Patent Document 1 includes: a processing tank that stores a processing liquid; a circulation path that circulates the processing liquid in the processing tank; a substrate holder that holds a substrate; and a lifter that raises and lowers the substrate holder between an immersion position in the processing tank and a standby position above the processing tank. The processing liquid is a mixture of a sulfuric acid and a hydrogen peroxide.
Patent Document 1: Japanese Patent Laid-open Publication No. 2011-114305
According to one embodiment of the present disclosure, a substrate processing apparatus includes: a processing tank configured to store a processing liquid for processing a substrate; a circulation path through which the processing liquid is taken out from the processing tank and is returned to the processing tank; a substrate holder configured to hold the substrate; a lifter configured to raise and lower the substrate holder between an immersion position inside the processing tank and a standby position above the processing tank; and a controller configured to control the lifter, wherein the processing liquid is a mixed liquid obtained by mixing a first component and a second component and generates a heat of mixing, and the controller is configured to perform a control to immerse the substrate in the mixed liquid before a temperature of the mixed liquid rises due to the heat of mixing and reaches a peak temperature.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.
Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components may be denoted by the same reference numerals, and a description thereof may be omitted. In the present specification, the X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to each other. The X-axis direction and Y-axis direction are horizontal directions, and the Z-axis direction is a vertical direction. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, systems, and components have not been described in detail so as not to unnecessarily obscure aspects of the various embodiments.
In the related art, a batch-type apparatus and a single-wafer-type apparatus are known as substrate processing apparatuses. In the batch-type apparatus, a plurality of substrates are processed at once by immersing the substrates in a processing liquid at the same time. On the other hand, in the single-wafer-type apparatus, a substrate is horizontally held and rotated while a processing liquid is dropped onto an upper surface of the substrate. The technique of the present disclosure relates to a batch-type technique. The batch-type technique is suitable for long-term processing compared to a single-wafer-type technique.
A mixed liquid obtained by mixing a first component and a second component may be used as the processing liquid. Here, the mixed liquid may contain a third component. The mixed liquid generates heat of mixing. The heat of mixing is reaction heat generated by mixing a plurality of types of components. For example, when a sulfuric acid and a hydrogen peroxide solution (H2O2+H2O) are mixed with each other, heat of dilution of the sulfuric acid, heat of hydration of the sulfuric acid and water, or heat of reaction of the sulfuric acid and the hydrogen peroxide is generated. Multiple kinds of heat of mixing may occur in a stepwise manner depending on a temperature.
The higher the temperature, the more likely the exothermic reaction is to proceed, and the temperature of the mixed liquid may rise rapidly. As a result, the temperature of the mixed liquid may overshoot a target temperature. Thereafter, when the substrates start to be immersed in the mixed liquid after the temperature of the mixed liquid is stabilized at the target temperature, the waiting time until the start of immersion becomes longer. As a result, the processing capacity of the substrate processing apparatus (the number of substrates processed per unit time) is reduced.
In addition, when the temperature of the mixed liquid overshoots the target temperature, thermal decomposition is promoted. For example, the hydrogen peroxide decomposes into water and oxygen at a high temperature. The concentration of the hydrogen peroxide drops significantly below a target concentration due to the thermal decomposition. Even if the mixed liquid is replenished with the hydrogen peroxide thereafter, it is difficult to restore the concentration of the hydrogen peroxide in the mixed liquid to the target concentration.
As will be described in detail later, in the technique of the present disclosure, the substrates are immersed in the mixed liquid before the temperature of the mixed liquid rises due to the heat of mixing and reaches a peak temperature (maximum temperature). As a result, the substrates can be processed before the concentration of the thermally decomposing component is significantly reduced, and the substrates can be processed efficiently. Further, the waiting time until the start of immersion can be shortened, and the substrates can be processed efficiently.
First, a substrate processing apparatus 1 according to an embodiment will be described with reference to
The processing tank 10 stores a processing liquid L for processing substrates W. The processing tank 10 includes, for example, an inner tank 11 and an outer tank 12. The inner tank 11 stores the processing liquid L. The plurality of substrates W are immersed in the processing liquid L stored in the inner tank 11. The outer tank 12 collects the processing liquid L overflowing from the inner tank 11.
The processing liquid L is a mixed liquid obtained by mixing a first component and a second component, and is a mixed liquid that generates heat of mixing. For example, the first component is a sulfuric acid and the second component is a hydrogen peroxide. The processing liquid L may contain a third component. The third component is, for example, water. The processing liquid L is, for example, an aqueous solution containing the sulfuric acid and the hydrogen peroxide (so-called SPM: sulfuric acid-hydrogen peroxide mixture).
The processing liquid L is used as, for example, an etching liquid. The etchant removes desired films formed on the substrates W. For example, the SPM removes resist films, polysilicon films, amorphous silicon films, or metal films. The metal films are, for example, tungsten films.
The SPM used to remove the metal films has a relatively high target concentration of hydrogen peroxide and a relatively high target temperature. A target value of the mixing ratio (mass ratio) of hydrogen peroxide and sulfuric acid (H2O2/H2SO4) may be greater than ¼. The target temperature may be 125 degrees C. to 170 degrees C., more specifically 130 degrees C. to 170 degrees C.
The higher the target concentration of hydrogen peroxide, the more likely the heat of mixing is generated. In addition, the higher the target temperature, the more likely the heat of mixing is generated. Therefore, the technique of the present disclosure is particularly effective when using SPM to remove the metal films.
The first component supplier 15 supplies the first component constituting the processing liquid L to the processing tank 10. The first component supplier 15 is, for example, a sulfuric acid supplier. The sulfuric acid may be supplied to the processing tank 10 in the form of an aqueous solution. A supply destination of the sulfuric acid is the inner tank 11. The first component supplier 15 includes, for example, an opening/closing valve, a flow controller, and a flow meter (not illustrated).
The second component supplier 17 supplies the second component constituting the processing liquid L to the processing tank 10. The second component supplier 17 is, for example, a hydrogen peroxide supplier. The hydrogen peroxide may be supplied to the processing tank 10 in the form of an aqueous solution. A supply destination of the hydrogen peroxide is the inner tank 11. The second component supplier 17 includes, for example, an opening/closing valve, a flow controller, and a flow meter (not illustrated).
The discharger 18 discharges the processing liquid L stored in the processing tank 10. For example, the discharger 18 discharges the processing liquid L stored in the inner tank 11. The discharger 18 includes a discharge path 18a and an opening/closing valve 18b. One end of the discharge path 18a is connected to the inner tank 11. The opening/closing valve 18b opens and closes the discharge path 18a under the control of the controller 90.
The circulation path 20 takes out the processing liquid L from the processing tank 10 and returns the same to the processing tank 10. The processing liquid L may be circulated, and the mixing of a plurality of components constituting the processing liquid L may be promoted. For example, the circulation path 20 takes out the processing liquid L from the outer tank 12 and returns the same to the inner tank 11. The circulation path 20 has an upstream end connected to the outer tank 12 and a downstream end connected to a nozzle 29 provided inside the inner tank 11.
In the middle of the circulation path 20, for example, from the upstream side to the downstream side, a first opening/closing valve 21, a cooling gas source 22, a pump 23, a first cooling gas discharger 24, a heater 25, a second cooling gas discharger 26, a second opening/closing valve 27, and a filter 28 are provided in this order. In addition, the types and order of devices provided in the middle of the circulation path 20 are not particularly limited.
The cooling gas source 22 supplies a cooling gas to the circulation path 20 while the first opening/closing valve 21 closes the circulation path 20 in the vicinity of the outer tank 12. A nitrogen gas or a dry air is used as the cooling gas. The cooling gas discharges the processing liquid L remaining in the circulation path 20 to the outside of the circulation path 20 from the first cooling gas discharger 24 and the second cooling gas discharger 26. As a result, the circulation path 20 can be cooled down.
While the cooling gas source 22 supplies the cooling gas to the circulation path 20, the controller 90 causes the pump 23 to run idle. In addition, while the cooling gas source 22 supplies the cooling gas to the circulation path 20, the second opening/closing valve 27 closes the circulation path 20 to prevent the filter 28 from drying. The second opening/closing valve is provided on the upstream side of the filter 28.
The cooling gas source 22 supplies a cooling gas at room temperature to the circulation path 20, but may supply a cooling gas at a temperature lower than the room temperature to the circulation path 20. The circulation path 20 can be efficiently cooled down. The cooling gas source 22 may have a cooling machine that cools the cooling gas at the room temperature to a temperature lower than the room temperature. The cooling gas source 22 is an example of a cooler.
Instead of (or in addition to) the cooling gas source 22, a cooling liquid supplier 16 may be used as a cooler. The cooling liquid supplier 16 supplies a cooling liquid to the circulation path 20 via the processing tank 10 (e.g., the outer tank 12). As the cooling liquid, for example, sulfuric acid, which is the first component, is used. The cooling liquid discharges the processing liquid L remaining in the circulation path 20 to the inner tank 11. As a result, the circulation path 20 can be cooled down.
The controller 90 operates the pump 23 to supply the cooling liquid to the circulation path 20. In addition, the controller 90 opens the first opening/closing valve 21 and the second opening/closing valve 27 to allow the cooling liquid to pass through the same. After passing through the circulation path 20 and being discharged to the inner tank 11, the cooling liquid is discharged to the outside of the inner tank 11 from the discharger 18.
The cooling liquid supplier 16 supplies a cooling liquid at the room temperature to the circulation path 20, but may supply a cooling liquid at a temperature lower than the room temperature to the circulation path 20. The circulation path 20 can be efficiently cooled down. The cooling liquid supplier 16 may have a cooling machine that cools the cooling liquid at the room temperature to a temperature lower than the room temperature.
The substrate holder 30 holds substrates W as illustrated, for example, in
The lifter 40 raises and lowers the substrate holder 30 between an immersion position inside the processing tank 10 and a standby position above the processing tank 10. The lifter 40 includes, for example, a motor (not illustrated) and a ball screw configured to convert a rotational motion of the motor into a linear motion of the substrate holder 30. In addition, the lifter 40 may move the substrate holder 30 in a horizontal direction.
The controller 90 is, for example, a computer, and includes a calculator 91 such as a central processing unit (CPU) and a storage 92 such as a memory. The storage 92 stores programs for controlling various processes executed in the substrate processing apparatus 1. The controller 90 controls an operation of the substrate processing apparatus 1 by causing the calculator 91 to execute the programs stored in the storage 92.
Next, a substrate processing method according to an embodiment will be described with reference to
Processing after step S101 illustrated in
First, from time t0 to time t1, the discharger 18 discharges the processing liquid L from the inner tank 11 to empty the inner tank 11 (step S101). During this time, the pump 23 sends the processing liquid L from the outer tank 12 to the inner tank 11 via the circulation path 20 to empty the outer tank 12. By step S101, the interiors of the inner tank 11 and the outer tank 12 become empty. However, since the processing liquid L remains in the circulation path 20, the circulation path 20 remains at a high temperature.
Subsequently, the circulation path 20 is cooled down from time t1 to time t2 (step S102). Specifically, for example, supplying, by the cooling liquid supplier 16, a cooling liquid to the circulation path 20 via the outer tank 12 and discharging, by the discharger 18, the cooling liquid from the inner tank 11 are alternately and repeatedly performed. Instead of (or in addition to) the cooling liquid supplier 16, the cooling gas source 22 may be used to cool down the circulation path 20. In any case, by cooling down the circulation path 20, residual heat can be removed, and promotion of an exothermic reaction due to the residual heat can be prevented.
Subsequently, from time t2 to time t3, the first component supplier 15 supplies the sulfuric acid at room temperature to the inner tank 11, and the second component supplier 17 supplies the hydrogen peroxide at room temperature to the inner tank 11 (step S103). The hydrogen peroxide is supplied in the form of an aqueous solution. As the supply of the hydrogen peroxide solution progresses, the mixture of the hydrogen peroxide solution and the sulfuric acid generates heat of mixing, and a temperature T of the processing liquid L rises.
Next, at time t3, the pump 23 starts circulation of the processing liquid L (step S104). The circulation promotes the mixing of the hydrogen peroxide solution and the sulfuric acid, and the heat of mixing further increases the temperature T of the processing liquid L. As illustrated in
Next, at time t4, the heater 25 starts heating of the processing liquid L (step S105). The heater 25 is provided in the circulation path 20, but may be provided in the processing tank 10. The heater 25 is an example of a heating part that heats the processing liquid L. After time t4, the temperature T of the processing liquid L rises again, and heat of mixing is generated again.
Next, at time t5, when the temperature T of the processing liquid L reaches an immersion start temperature TSTA (e.g., 130 degrees C.), the lifter 40 lowers the substrate holder 30 from the standby position to the immersion position, so that the substrates W are immersed in the processing liquid L (step S106). The immersion start temperature TSTA may be set higher than an etching start temperature TETC to be described later (see
After time t5, the temperature T of the processing liquid L overshoots a target temperature TPRE (e.g., 140 degrees C.) due to the heat of mixing. The target temperature TPRE is higher than the immersion start temperature TSTA. The temperature T of the processing liquid L exceeds the target temperature TPRE and then reaches a peak temperature TMAX (e.g., 160 degrees C.). The peak temperature TMAX is higher than the target temperature TPRE.
The peak temperature TMAX is controlled not to exceed a threshold. The threshold is determined based on, for example, a heat-resistant temperature of the processing tank 10. When the peak temperature TMAX exceeds the threshold, the controller 90 may reduce the amount of the hydrogen peroxide solution supplied to the processing tank 10 from time t2 to time t3 to reduce the generated amount of heat of mixing. The temperature T starts to drop after reaching the peak temperature TMAX.
Next, at time t6, the controller 90 detects that the temperature T reaches the peak temperature TMAX by detecting that the temperature T starts to decrease from the peak temperature TMAX. The temperature T is detected by a temperature detector 51 (see
After time t6, the controller 90 controls the heater 25 with a setting different from that before time t6. That is, the controller 90 controls the heater 25 with different settings before and after the temperature T of the processing liquid L reaches the peak temperature TMAX. The heater 25 may be appropriately controlled in a period in which a large amount of heat of mixing is generated and a period in which a small amount of heat of mixing is generated.
For example, the controller 90 feedback-controls the heater 25 by using different transfer functions before and after the temperature T of the processing liquid L reaches the peak temperature TMAX (before and after time t6). When the feedback control is PID control or PI control, the transfer functions include at least a proportional gain Kp and an integral gain Ki. The proportional gain Kp before time t6 is set larger than the proportional gain Kp after time t6. The integral gain Ki before time t6 is set smaller than the integral gain Ki after time t6.
In addition, the controller 90 may perform a constant-current control of the heater 25 with different current values, for example, before and after the temperature T of the processing liquid L reaches the peak temperature TMAX (before and after time t6). The supply current to the heater 25 before time t6 may be set smaller than the supply current to the heater 25 after time t6. This is because the temperature is positively adjusted by using the heater 25 after time t6.
In the period from the start of mixing of the sulfuric acid and the hydrogen peroxide until the temperature T of the processing liquid L reaches the peak temperature TMAX, a total heat quantity of mixing is greater than a total heat quantity of the heater 25. On the other hand, the total heat quantity of the mixing is smaller than the total heat quantity of the heater 25 in the period from the time when the temperature T of the processing liquid L reaches the peak temperature TMAX to the time when the substrates W are completely immersed.
After time t6, the second component supplier 17 may supply the hydrogen peroxide to the processing tank 10. When the temperature T of the processing liquid L overshoots the target temperature TPRE, thermal decomposition of the hydrogen peroxide is promoted. When the hydrogen peroxide is not replenished, the concentration of the hydrogen peroxide is significantly lower than a target concentration C1PRE, as indicated by the dashed line in
Therefore, after time t6, the second component supplier 17 may supply the hydrogen peroxide to the processing tank 10 to suppress a decrease in the concentration of the hydrogen peroxide. After time t6, the generation of heat of mixing subsides. When the hydrogen peroxide is replenished after the generation of heat of mixing subsides, excessive temperature rise of the processing liquid L can be suppressed.
Further, in
Next, at time t7, the lifter 40 raises the substrate holder 30 from the immersion position to the standby position, and pulls up the substrates W out of the processing liquid L. Thus, the immersion of the substrates W in the processing liquid L is terminated. The immersion time is set in advance by experiments or the like, and is set in advance based on, for example, a film thickness and an etching rate of an object target.
The controller 90 may correct the immersion time for each batch so that the etching amount is within an allowable range. For example, the controller 90 acquires at least one of a temperature profile and a concentration profile of the processing liquid L, and corrects the immersion time based on data thus acquired. This is because the etching rate depends on the temperature T and the hydrogen peroxide concentration C1.
As illustrated in
As illustrated in
The hydrogen peroxide concentration C1 is detected by a concentration detector 52 (
As described above, according to the present embodiment, the substrates W are immersed in the processing liquid L before the temperature T of the processing liquid L rises due to the heat of mixing and reaches the peak temperature TMAX. As a result, the substrates W can be processed before the concentration of the thermally decomposing component (e.g., hydrogen peroxide) drops significantly, so the substrates W can be processed efficiently. Further, the waiting time until the start of immersion can be shortened, so the substrate W can be processed efficiently.
The substrate processing apparatus 1 may include a predictor configured to predict the temperature profile in the process in which the temperature T of the processing liquid L rises toward the peak temperature TMAX. The predictor may be a part of the controller 90. The predictor predicts a temperature profile of a current batch based on, for example, temperature profiles of past batches. The temperature profiles vary little between batches.
The controller 90 performs control to transmit, to a transfer device 60 (see
In the present embodiment, when the temperature T of the processing liquid L reaches the immersion start temperature TSTA (e.g., 130 degrees C.) at time t5, the immersion of the substrates W is started, but the technique of the present disclosure is not limited thereto. For example, the immersion of the substrates W may be started after the circulation of the processing liquid L is started (time t3) and before the heating by the heater 25 is started (time t4).
Before the start of heating by the heater 25 (time t4), the sulfuric acid and the hydrogen peroxide solution are uniformly mixed, and the temperature T of the processing liquid L is temporarily stabilized. The immersion of the substrates W may begin while the temperature T is stable. In this case, it is easier to manage the time of starting the immersion of the substrates W compared to the case where the immersion of the substrates W is started while the temperature T is rising.
In addition, before the start of heating by the heater 25 (time t4), the temperature T is lower than the etching start temperature TETC, and etching does not substantially start. The etching amount can be managed by an elapsed time from the time when the temperature T reaches the etching start temperature TETC, or the like. This facilities the management of the etching amount. The immersion of the substrates W may be started while the temperature T is stable below the etching start temperature TETC.
According to an aspect of the present disclosure, substrates can be efficiently processed when the substrates are immersed in a mixed liquid that generates heat of mixing.
Although the embodiments of the substrate processing apparatus and the substrate processing method according to the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments or the like. Various changes, modifications, substitutions, additions, deletions, and combinations may be made within the scope of the claims. Of course, these also fall within the technical scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-119411 | Jul 2022 | JP | national |
