WO2020188990A1 - Substrate treatment method - Google Patents

Substrate treatment method Download PDF

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Publication number
WO2020188990A1
WO2020188990A1 PCT/JP2020/001869 JP2020001869W WO2020188990A1 WO 2020188990 A1 WO2020188990 A1 WO 2020188990A1 JP 2020001869 W JP2020001869 W JP 2020001869W WO 2020188990 A1 WO2020188990 A1 WO 2020188990A1
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Prior art keywords
phosphoric acid
substrate
tank
acid solution
processing method
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PCT/JP2020/001869
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French (fr)
Japanese (ja)
Inventor
朋宏 高橋
武知　圭
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株式会社Ｓｃｒｅｅｎホールディングス
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Publication of WO2020188990A1 publication Critical patent/WO2020188990A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching

Definitions

  • the present invention relates to a substrate processing method, and more particularly to a substrate processing method using a phosphoric acid-containing processing liquid.
  • a substrate processing method for processing a semiconductor substrate in order to manufacture a three-dimensional memory device is disclosed.
  • This semiconductor substrate has a laminated film in which silicon oxide films and silicon nitride films are alternately laminated on a silicon substrate. Further, the semiconductor substrate has a trench penetrating the laminated film.
  • the silicon nitride film is wet-etched by immersing the semiconductor substrate in a heated phosphoric acid solution in the processing tank. At this time, the phosphoric acid solution comes into contact with each layer of the laminated film through the trench of the semiconductor substrate to selectively remove the silicon nitride film.
  • the phosphoric acid solution used in the etching process overflows from the inner tank and is stored in the outer tank. The pump sucks the phosphoric acid solution stored in the outer tank and refluxes it through the circulation path. In the process of reflux, the phosphoric acid solution is heated and supplied into the treatment tank again.
  • the phosphoric acid-containing treatment liquid in contact with the substrate can be replaced to some extent by the flow of the phosphoric acid solution with reflux.
  • the phosphoric acid solution in contact with the substrate may have a portion that is difficult to be replaced by mere flow.
  • the phosphoric acid solution is unlikely to be replaced at a deep position in the trench.
  • the silicon nitride film located deeper among the plurality of silicon nitride films pierced by the trench is less susceptible to the progress of etching from the trench than the silicon nitride film located shallowly. Therefore, the non-uniformity of the etching progress becomes large.
  • the present invention has been made to solve the above problems, and an object of the present invention is to provide a substrate processing method capable of making the progress of etching of a substrate by a phosphoric acid-containing treatment liquid uniform. ..
  • the substrate processing method of the present invention has the following steps.
  • a dipping step of immersing the substrate in the phosphoric acid-containing treatment liquid in the first tank is performed.
  • an ascending step is performed in which at least a part of the substrate is raised by passing through the liquid surface of the phosphoric acid-containing treatment liquid in the first tank and upward.
  • a descending step is performed in which at least a part of the substrate is lowered by passing through the liquid surface of the phosphoric acid-containing treatment liquid in the first tank or in the second tank different from the first tank.
  • the lowering step may be a step of lowering at least a part of the substrate downward by passing through the liquid surface of the phosphoric acid-containing treatment liquid in the first tank.
  • the lowering step may be a step of lowering at least a part of the substrate downward by passing through the liquid surface of the phosphoric acid-containing treatment liquid in the second tank.
  • the ascending step may be performed by ascending the entire substrate upward through the liquid level of the phosphoric acid-containing treatment liquid in the first tank.
  • the dipping step may include an exposure step of exposing at least one silicon nitride film of the substrate to the phosphoric acid-containing treatment liquid in the first tank.
  • the substrate contains a laminate that alternately has a plurality of first films as at least one silicon nitride film and a plurality of second films made of a material that is less likely to be etched by phosphoric acid than silicon nitride. Good.
  • the laminate has trenches penetrating the plurality of first films and the plurality of second films, and the phosphoric acid-containing treatment liquid penetrates into the trenches.
  • the second film may be a silicon oxide film.
  • the dipping step may include an exposure step of exposing the tungsten film of the substrate to the phosphoric acid-containing treatment liquid in the first tank.
  • the phosphoric acid-containing treatment liquid does not have to be bubbled in the ascending step and the descending step.
  • the phosphoric acid-containing treatment liquid may be bubbled with a gas.
  • the gas may be an inert gas.
  • the main surface of the substrate may be parallel in the vertical direction.
  • the substrate passes through the liquid surface of the phosphoric acid-containing treatment liquid and is moved upward.
  • the phosphoric acid-containing treatment liquid is effectively removed from the substrate due to the surface tension of the phosphoric acid-containing treatment liquid.
  • the phosphoric acid-containing treatment liquid is supplied again to the portion where the phosphoric acid-containing treatment liquid has been removed.
  • FIG. 5 is a cross-sectional view schematically showing a second step of the substrate processing method according to the first embodiment of the present invention. It is sectional drawing which shows roughly the 3rd step of the substrate processing method in Embodiment 1 of this invention.
  • FIG. 5 is a cross-sectional view schematically showing a fourth step of the substrate processing method according to the first embodiment of the present invention. It is sectional drawing which shows typically the 5th step of the substrate processing method in Embodiment 1 of this invention.
  • FIG. 5 is a cross-sectional view schematically showing a seventh step of the substrate processing method according to the second embodiment of the present invention. It is sectional drawing which shows schematic 8 steps of the substrate processing method in Embodiment 2 of this invention. It is sectional drawing which shows schematic 9th steps of the substrate processing method in Embodiment 2 of this invention.
  • FIG. 5 is a cross-sectional view schematically showing a tenth step of the substrate processing method according to the second embodiment of the present invention. It is sectional drawing which shows roughly the 1st step of the substrate processing method in Embodiment 3 of this invention. It is sectional drawing which shows typically the 2nd step of the substrate processing method in Embodiment 3 of this invention. It is sectional drawing which shows roughly the 3rd step of the substrate processing method in Embodiment 3 of this invention.
  • FIG. 1 is a diagram schematically showing the configuration of the substrate processing apparatus 100 according to the first embodiment.
  • the substrate 500 processed by the substrate processing apparatus 100 and the phosphoric acid solution ET (phosphoric acid-containing processing liquid) used by the substrate processing apparatus 100 are indicated by virtual lines (two-point chain line). There is.
  • one or more materials may be further dissolved in the phosphoric acid solution ET.
  • the substrate processing apparatus includes a tank 101 (first tank), an outer tank 102, a lifter 51 (board holding unit), an actuator 52 (lifter driving unit), and a solution supply source 11 (phosphoric acid-containing processing liquid supply source).
  • the tank 101 has at least one liquid injection port 111 and at least one gas injection port 112.
  • the tank 101 is a container for storing the phosphoric acid solution ET for processing the substrate 500.
  • the phosphoric acid solution ET stored in the tank 101 has a liquid level SF.
  • the outer tank 102 is a container for storing the phosphoric acid solution ET that overflows from the liquid level SF.
  • the pump 16 and the heater 17 are provided in the piping path from the outer tank 102 to the liquid injection port 111.
  • the heated phosphoric acid solution ET is refluxed.
  • the phosphoric acid solution ET sucked out from the outer tank 102 is heated and then discharged from the liquid injection port 111 into the tank 101.
  • the solution supply source 11 supplies a new phosphoric acid solution (phosphoric acid-containing treatment liquid) to the tank 101 according to the control by the valve 12.
  • FIG. 1 shows a configuration in which the phosphoric acid solution is directly supplied to the tank 101, other configurations may be used.
  • the phosphoric acid solution may be indirectly supplied to the tank 101 via at least one of the above-mentioned reflux path and the outer tank 102.
  • the gas supply source 21 supplies gas to the gas inlet 112 according to the control by the valve 22.
  • bubbling into the phosphoric acid solution ET stored in the tank 101 is performed according to the control by the valve 22.
  • the tank 101 is provided with a plurality of gas inlets 112.
  • the lifter 51 holds at least one substrate 500.
  • the lifter 51 holds a plurality of substrates 500, in which case batch processing will be performed.
  • the actuator 52 displaces the lifter 51 up and down.
  • the relative position of the substrate 500 held by the lifter 51 can be changed with reference to the position of the liquid level SF of the phosphoric acid solution ET in the vertical direction. Therefore, the rate at which the substrate 500 is immersed in the phosphoric acid solution ET is controlled.
  • the actuator 52 has, for example, a servomotor or a timing belt.
  • the valve 22 and the actuator 52 may operate in response to a command from a control unit (not shown).
  • the control unit is typically composed of electrical circuits and includes a processor and a storage device.
  • the processor issues commands to the valve 22 and the actuator 52 by executing a program stored in the storage device.
  • FIGS. 2 to 6 are cross-sectional view schematically showing the first to fifth steps of the substrate processing method using the substrate processing apparatus 100 (FIG. 1) in the first embodiment.
  • the silicon nitride film (not shown in FIGS. 2 to 6) included in the substrate 500 is etched.
  • the phosphoric acid solution ET is stored in the tank 101. At least one, preferably a plurality, of substrates 500 are held by the lifter 51 above the liquid level SF of the phosphoric acid solution ET. Next, the actuator 52 lowers the lifter 51 toward the liquid level SF (see the broken line arrow in the figure).
  • the substrate 500 is arranged below the liquid level SF. It is preferable that the phosphoric acid solution ET is not bubbled during the descent of the lifter 51.
  • the substrate 500 is immersed in the phosphoric acid solution ET in the tank 101 through the above-mentioned steps.
  • the dipping process is started.
  • the position of the substrate 500 is preferably fixed.
  • the main surface MS of the substrate 500 is preferably parallel in the vertical direction.
  • the thickness direction of the substrate 500 is preferably along the horizontal direction.
  • the phosphoric acid solution ET is preferably bubbled with a gas.
  • the bubble BB is generated by the supply of gas from the gas inlet 112.
  • the gas is preferably an inert gas, for example nitrogen gas (N 2 ).
  • the ascending step is then performed. Specifically, at least a part of the substrate 500 is raised upward through the liquid level SF of the phosphoric acid solution ET in the tank 101. As shown in FIG. 6, the ascending step is preferably performed by ascending the entire substrate 500 upward through the liquid level SF of the phosphoric acid solution ET in the tank 101. It is preferable that the phosphoric acid solution ET is not bubbled during the lifting step of the lifter 51.
  • the lowering step is then performed. Specifically, at least a part, preferably the whole, of the substrate 500 is lowered by passing through the liquid level SF of the phosphoric acid solution ET in the tank 101.
  • the phosphoric acid solution ET is preferably not bubbled.
  • the ascending step is then performed again.
  • the set of these steps is preferably performed at least once, more preferably a plurality of times. For example, three or more sets each composed of a descending step, a dipping step, and an ascending step may be periodically performed.
  • the set of the ascending step and the descending step is repeated a plurality of times.
  • This set may be repeated 10 times or more.
  • this set is repeated about 40 to 50 times during the substrate processing for about 2 hours, and in this case, the frequency of setting (the number of times per unit time) is once every few minutes.
  • a first step of repeating the set of the ascending step and the descending step with the first frequency and a second step of repeating the set of the ascending step and the descending step with the second frequency are performed after the first step.
  • the 2nd frequency is lower than the 1st frequency.
  • the substrate processing method of the present embodiment is completed.
  • the substrate 500 may be washed with water, if necessary.
  • the water washing step may be performed by supplying water to the tank 101, or may be performed in another tank.
  • the substrate 500 is moved upward through the liquid level SF of the phosphoric acid solution ET by the ascending step (FIGS. 5 and 6).
  • the phosphoric acid solution ET is effectively removed from the substrate 500 due to the surface tension of the phosphoric acid solution ET.
  • the phosphoric acid solution ET is supplied again to the portion where the phosphoric acid solution ET has been removed by the subsequent descending step (see FIGS. 2 and 3).
  • the portion of the phosphoric acid solution ET in contact with the substrate 500 that is difficult to be replaced by mere flow is effectively replaced. Therefore, the progress of etching of the substrate 500 by the phosphoric acid solution ET can be made uniform.
  • An example of a portion that is difficult to be replaced only by a simple flow will be described in detail in the third embodiment described later.
  • the lowering step is different from the second embodiment described later, and in the present embodiment, as shown in FIGS. 2 and 3, the lowering substrate passes through the liquid level SF of the phosphoric acid solution ET in the tank 101 and downwards. It is a step of lowering at least a part of 500. As a result, the progress of etching in the tank 101 can be made uniform as described above.
  • the ascending step is preferably performed by ascending the entire substrate 500 upward through the liquid level SF of the phosphoric acid solution ET in the tank 101. Thereby, the phosphoric acid solution ET can be removed more effectively from the substrate 500.
  • the phosphoric acid solution ET is not bubbled in the ascending step (see FIGS. 5 and 6) and the descending step (see FIGS. 2 and 3). As a result, it is possible to prevent the posture of the substrate 500 from becoming unstable due to bubbling in the ascending step and the descending step.
  • the phosphoric acid solution ET is preferably bubbled with gas.
  • the flow of phosphate solution ET caused by bubbling further facilitates the substitution of phosphate solution ET.
  • the bubbling gas is preferably an inert gas. This avoids unnecessary chemical action caused by the gas.
  • the main surface MS of the substrate 500 is preferably parallel in the vertical direction.
  • the substrate 500 can be moved in the vertical direction by moving the substrate 500 along the main surface MS. Therefore, the substrate 500 can be moved in and out of the tank 101 by moving the substrate 500 along the main surface MS.
  • a first step of repeating the set of the ascending step and the descending step with the first frequency and a second step of repeating the set of the ascending step and the descending step with the second frequency are performed after the first step.
  • the 2nd frequency is lower than the 1st frequency.
  • the etching tends to proceed rapidly in the initial stage, so that the silicon concentration in the phosphoric acid solution ET in contact with the substrate 500 also tends to increase rapidly. Therefore, in the initial stage, it is preferable that the ascending step and the descending step are set at a relatively high first frequency in order to suppress the concentration unevenness. On the other hand, in the subsequent stage, the increase in the silicon concentration becomes gradual, so it is preferable that the ascending step and the descending step are set at a relatively low second frequency. As a result, it is possible to suppress a decrease in the processing speed due to the temporary removal of the phosphoric acid solution ET.
  • the temperature of the substrate 500 heated by the phosphoric acid solution ET temporarily decreases between the ascending step and the descending step, which is the progress of etching. It tends to slow down.
  • the second frequency which is lower than the first frequency, the adverse effect of this temperature decrease can be suppressed.
  • FIGS. 7 to 16 are cross-sectional view schematically showing the first to tenth steps of the substrate processing method according to the second embodiment.
  • the substrate processing apparatus used in the present embodiment further includes a tank 201 (second tank) and an outer tank 202 as shown in addition to the configuration of the substrate processing apparatus 100.
  • the tank 201 has at least one liquid injection port 211 and at least one gas injection port 212. Similar to the tank 101 (FIG. 1), the tank 201 is provided with a solution supply source 11, a valve 12, a gas supply source 21, a valve 22, a pump 16, and a heater 17, although not shown. Has been done.
  • the actuator 52 can not only displace the lifter 51 up and down, but also displace it in the horizontal direction.
  • the substrate 500 held by the lifter 51 can be displaced from the position on the tank 101 to the position on the tank 201.
  • the lifter 51 also has a function as a slider.
  • the phosphoric acid solution ET is stored in the tank 101 and the tank 201. Above the liquid level SF of the phosphoric acid solution ET in the tank 101, at least one, preferably a plurality of, substrates 500 are held by the lifter 51. Next, the actuator 52 lowers the lifter 51 toward the liquid level SF (see the broken line arrow in the figure).
  • the substrate 500 by lowering the lifter 51, at least a part, preferably the whole, of the substrate 500 is arranged below the liquid level SF. It is preferable that the phosphoric acid solution ET is not bubbled during the descent of the lifter 51.
  • the substrate 500 is immersed in the phosphoric acid solution ET in the tank 101 through the above-mentioned steps.
  • the dipping step in the tank 101 is started.
  • the position of the substrate 500 is preferably fixed.
  • the main surface MS of the substrate 500 is preferably parallel in the vertical direction.
  • the thickness direction of the substrate 500 is preferably along the horizontal direction.
  • the phosphoric acid solution ET is preferably bubbled with a gas.
  • the bubble BB is generated by the supply of gas from the gas inlet 112.
  • the gas is preferably an inert gas, for example N 2 .
  • the ascending step in the tank 101 is then performed. Specifically, at least a part of the substrate 500 is raised upward through the liquid level SF of the phosphoric acid solution ET in the tank 101. As shown in FIG. 11, the ascending step is preferably performed by ascending the entire substrate 500 upward through the liquid level SF of the phosphoric acid solution ET in the tank 101. It is preferable that the phosphoric acid solution ET is not bubbled during the lifting step of the lifter 51.
  • the actuator 52 displaces the lifter 51 from the position above the tank 101 to the position above the tank 201 (see the dashed arrow in the figure).
  • the lowering step is then performed. Specifically, at least a part, preferably the whole, of the substrate 500 is lowered as it passes through the liquid level SF of the phosphoric acid solution ET in the tank 201.
  • the phosphoric acid solution ET is preferably not bubbled.
  • this initiates the dipping step in tank 201.
  • the position of the substrate 500 is preferably fixed.
  • the main surface MS of the substrate 500 is preferably parallel in the vertical direction. In other words, the thickness direction of the substrate 500 is preferably along the horizontal direction.
  • the phosphoric acid solution ET is preferably bubbled with a gas.
  • the bubble BB is generated by the supply of gas from the gas inlet 212.
  • the gas is preferably an inert gas, for example N 2 .
  • the ascending step in the tank 201 is then performed. This completes the substrate processing method of the present embodiment.
  • the substrate processing method is performed using two tanks 101 and 102 has been described above, three or more tanks may be used. Further, the components of the phosphoric acid solution ET in the tank 101 and the components of the phosphoric acid solution ET in the tank 101 may be different from each other. Thereby, for example, the etching rate by the phosphoric acid solution ET may be relatively low in the tank 101 and relatively high in the tank 201.
  • the progress of etching of the substrate 500 can be made uniform for the same reason as in the case of the first embodiment described above.
  • the treatment with the phosphoric acid solution ET is performed not only in the tank 101 but also in the second tank 201.
  • the product in the phosphoric acid solution ET during the substrate treatment (for example, in the phosphoric acid solution ET during the etching treatment of silicon nitride) is compared with the case where the treatment with the phosphoric acid solution ET is performed only in the tank 101. It is possible to suppress a decrease in the etching ability of the phosphoric acid solution ET due to an increase in the concentration of silicon) produced in the phosphoric acid solution. This effect is particularly large when the treatment for maintaining the etching ability of the phosphoric acid solution ET by gradually mixing a new phosphoric acid solution into the used phosphoric acid solution ET is not performed.
  • FIG. 17 to 19 are cross-sectional views schematically showing the first to third steps of the substrate processing method according to the third embodiment.
  • the substrate 500 to which the substrate processing method of the present embodiment is applied has at least one silicon nitride film 505.
  • the substrate 500 is composed of a plurality of sacrificial films 505 (first film) as at least one silicon nitride film 505, and a plurality of structural films 503 made of a material that is less likely to be etched by phosphoric acid than silicon nitride. (Second film) and a laminated body having alternately.
  • the laminate has a trench TR that penetrates the plurality of sacrificial films 505 and the plurality of structural films 503.
  • the trench TR has an opening OP on the main surface MS and extends in the thickness direction of the substrate 500.
  • the structural film 503 is preferably a silicon oxide film 503.
  • the substrate 500 may have a support layer 501 that supports the laminate.
  • the support layer is, for example, a silicon layer.
  • the immersion step (FIG. 4) is then performed by the substrate processing method described in the first embodiment described above.
  • the exposure step of exposing the silicon nitride film 505 to the phosphoric acid solution ET in the tank 101 (FIG. 4) is performed.
  • the substrate 500 includes the laminate having the trench TR described above.
  • the phosphoric acid solution ET penetrates into the trench TR from the opening OP by the exposure step.
  • each etching of the sacrificial film 505 starts to proceed horizontally from the trench TR.
  • the phosphoric acid solution ET is less likely to be replaced by the mere flow at the etching progress portion P2 of the sacrifice film 505 of the lowermost layer as compared with the etching progress portion P1 of the sacrifice film 505 of the uppermost layer. Therefore, assuming that the treatment for promoting the substitution is merely flow, the etching of the sacrificial film 505 of the lowermost layer is considerably less likely to proceed than that of the sacrificial film 505 of the uppermost layer, and as a result, the etching progresses. Non-uniformity tends to increase.
  • the substrate processing method described in the above-described first embodiment is used for the purpose of sufficiently replacing the phosphoric acid solution ET even at the etching progress portion P2.
  • the ascending step (FIGS. 5 and 6) of this substrate processing method the opening OP of the trench TR is moved from below to above the liquid level SF of the phosphoric acid solution ET.
  • the action of pulling out the phosphoric acid solution ET from the trench TR and the cavity GP formed by etching the sacrificial film 505 extending in the horizontal direction from the trench TR occurs. ..
  • the action of pulling out the phosphoric acid solution ET is also added to the portion P2.
  • the opening OP of the trench TR is moved from above to below the liquid level SF of the phosphoric acid solution ET by the descending step (FIGS. 2 and 3).
  • the descending step (FIGS. 2 and 3).
  • the phosphoric acid solution ET is sufficiently substituted at the location P2 as well.
  • the sacrificial film 505 (FIG. 17) is changed to the cavity GP by the substrate treatment.
  • the substrate 500 subjected to such processing can be used as a substrate for manufacturing a three-dimensional memory device (for example, a three-dimensional NAND memory device).
  • the immersion step includes an exposure step of exposing the silicon nitride film 505 (FIG. 17) to the phosphoric acid solution ET in the tank 101.
  • the silicon nitride film 505 can be etched.
  • the phosphoric acid solution ET invades the trench TR.
  • the phosphoric acid solution ET is less likely to be replaced in the vicinity of the deep portion P2 (FIG. 18) in the trench TR than in the vicinity of the shallow portion P1 (FIG. 18).
  • the silicon nitride film 505 located deeper is less likely to be etched than the silicon nitride film 505 located shallower.
  • the non-uniformity of the etching progress tends to increase.
  • the depth of the trench TR increases, so that the above problem can become more serious.
  • the phosphoric acid solution ET is effectively replaced even in the vicinity of the deep portion P2 (FIG. 18) in the trench TR for the reason described in the first embodiment. Therefore, the progress of etching of the substrate 500 can be made uniform.
  • the structural film 503 is preferably a silicon oxide film 503. As a result, the etching resistance of the structural film 503 with respect to the phosphoric acid solution ET can be sufficiently ensured.
  • the substrate processing method in the above-described first embodiment is used to perform the steps of FIGS. 17 to 19
  • the substrate processing method in the above-described second embodiment is used. It may be used.
  • the dipping step includes an exposure step of exposing the tungsten film of the substrate 500 to the phosphoric acid solution ET in the tank 101.
  • the phosphoric acid-containing treatment liquid is not a simple phosphoric acid solution, but a mixed acid containing at least one acid in addition to phosphoric acid is preferable, and for example, a mixed acid containing phosphoric acid, acetic acid and nitric acid is preferable.
  • a mixed acid containing phosphoric acid, acetic acid and nitric acid is preferable.

Abstract

According to the present invention, a substrate (500) is immersed in a phosphoric acid-containing treatment liquid (ET) in a first tank (101). Then, at least a part of the substrate (500) passes through a liquid level (SF) of the phosphoric acid-containing treatment liquid (ET) in the first tank (101) and is raised. Then, at least a part of the substrate (500) passes through a liquid level (SF) of a phosphoric acid-containing treatment liquid (ET) in the first tank (101) or in a second tank different from the first tank and is lowered.

Description

基板処理方法Substrate processing method
　本発明は、基板処理方法に関し、特に、リン酸含有処理液を用いた基板処理方法に関するものである。 The present invention relates to a substrate processing method, and more particularly to a substrate processing method using a phosphoric acid-containing processing liquid.
　特許文献１によれば、３次元メモリデバイスを製造するために半導体基板を処理する基板処理方法が開示されている。この半導体基板は、シリコン基板上に、酸化シリコン膜と窒化シリコン膜とを交互に積層した積層膜を有する。また半導体基板は、積層膜を貫通するトレンチを有する。この基板処理方法によれば、処理槽において、加熱されたリン酸溶液中に半導体基板を浸漬することで、窒化シリコン膜のウェットエッチング処理が行われる。このとき、リン酸溶液は、半導体基板のトレンチを通して積層膜の各層に接触して、窒化シリコン膜を選択的に除去する。エッチング処理に用いられたリン酸溶液は、内槽からオーバーフローして外槽に貯留される。ポンプは、外槽に貯留されたリン酸溶液を吸引し、循環路を通じて還流する。還流の過程で、リン酸溶液に対して、加熱と、処理槽内への供給とが再度行われる。 According to Patent Document 1, a substrate processing method for processing a semiconductor substrate in order to manufacture a three-dimensional memory device is disclosed. This semiconductor substrate has a laminated film in which silicon oxide films and silicon nitride films are alternately laminated on a silicon substrate. Further, the semiconductor substrate has a trench penetrating the laminated film. According to this substrate processing method, the silicon nitride film is wet-etched by immersing the semiconductor substrate in a heated phosphoric acid solution in the processing tank. At this time, the phosphoric acid solution comes into contact with each layer of the laminated film through the trench of the semiconductor substrate to selectively remove the silicon nitride film. The phosphoric acid solution used in the etching process overflows from the inner tank and is stored in the outer tank. The pump sucks the phosphoric acid solution stored in the outer tank and refluxes it through the circulation path. In the process of reflux, the phosphoric acid solution is heated and supplied into the treatment tank again.
特開２０１７－１１８０９２号公報Japanese Unexamined Patent Publication No. 2017-118092
　上記特許文献１に記載の技術によれば、リン酸溶液の還流にともなう流動によって、基板に接するリン酸含有処理液が、ある程度は置換され得る。しかしながら、基板に接するリン酸溶液は、単なる流動だけでは置換されにくい部分を有し得る。特に、トレンチにおける深い位置では、リン酸溶液が置換されにくい。これにより、トレンチによって貫かれた複数の窒化シリコン膜のうち深く位置する窒化シリコン膜は、浅く位置する窒化シリコン膜に比して、トレンチからのエッチングの進行を受けにくくなる。よって、エッチングの進行の不均一性が大きくなる。近年、３次元メモリデバイスの層数が増加してきており、それにともなってトレンチの深さが増大してきているので、上記問題はより深刻となり得る。また上記特許文献１に記載の技術の場合に限らず、基板に接するリン酸含有処理液が、単なる流動だけでは置換されにくい部分を有する場合、エッチングの進行の不均一性が大きくなり得る。 According to the technique described in Patent Document 1, the phosphoric acid-containing treatment liquid in contact with the substrate can be replaced to some extent by the flow of the phosphoric acid solution with reflux. However, the phosphoric acid solution in contact with the substrate may have a portion that is difficult to be replaced by mere flow. In particular, the phosphoric acid solution is unlikely to be replaced at a deep position in the trench. As a result, the silicon nitride film located deeper among the plurality of silicon nitride films pierced by the trench is less susceptible to the progress of etching from the trench than the silicon nitride film located shallowly. Therefore, the non-uniformity of the etching progress becomes large. In recent years, the number of layers of the three-dimensional memory device has been increasing, and the depth of the trench has been increasing accordingly, so that the above problem can become more serious. Further, not limited to the case of the technique described in Patent Document 1, when the phosphoric acid-containing treatment liquid in contact with the substrate has a portion that is difficult to be replaced only by a simple flow, the non-uniformity of the etching progress can be increased.
　本発明は以上のような課題を解決するためになされたものであり、その目的は、リン酸含有処理液による基板のエッチングの進行を均一化することができる基板処理方法を提供することである。 The present invention has been made to solve the above problems, and an object of the present invention is to provide a substrate processing method capable of making the progress of etching of a substrate by a phosphoric acid-containing treatment liquid uniform. ..
　本発明の基板処理方法は、以下の工程を有する。第１槽内のリン酸含有処理液に基板を浸漬する浸漬工程が行われる。浸漬工程の後に、第１槽内のリン酸含有処理液の液面を通過して上方へと、基板の少なくとも一部を上昇させる上昇工程が行われる。上昇工程の後に、第１槽内または第１槽と異なる第２槽内のリン酸含有処理液の液面を通過して下方へと基板の少なくとも一部を下降させる下降工程が行われる。 The substrate processing method of the present invention has the following steps. A dipping step of immersing the substrate in the phosphoric acid-containing treatment liquid in the first tank is performed. After the dipping step, an ascending step is performed in which at least a part of the substrate is raised by passing through the liquid surface of the phosphoric acid-containing treatment liquid in the first tank and upward. After the ascending step, a descending step is performed in which at least a part of the substrate is lowered by passing through the liquid surface of the phosphoric acid-containing treatment liquid in the first tank or in the second tank different from the first tank.
　下降工程は、第１槽内のリン酸含有処理液の液面を通過して下方へと基板の少なくとも一部を下降させる工程であってよい。下降工程は、第２槽内のリン酸含有処理液の液面を通過して下方へと基板の少なくとも一部を下降させる工程であってよい。 The lowering step may be a step of lowering at least a part of the substrate downward by passing through the liquid surface of the phosphoric acid-containing treatment liquid in the first tank. The lowering step may be a step of lowering at least a part of the substrate downward by passing through the liquid surface of the phosphoric acid-containing treatment liquid in the second tank.
　上昇工程は、第１槽内のリン酸含有処理液の液面を通過して上方へと、基板の全体を上昇させることによって行われてよい。 The ascending step may be performed by ascending the entire substrate upward through the liquid level of the phosphoric acid-containing treatment liquid in the first tank.
　浸漬工程は、基板が有する少なくとも１つの窒化シリコン膜を第１槽内のリン酸含有処理液にさらす暴露工程を含んでよい。暴露工程において、基板は少なくとも１つの窒化シリコン膜としての複数の第１膜と窒化シリコンに比してリン酸にエッチングされにくい材料からなる複数の第２膜とを交互に有する積層体を含んでよい。積層体は複数の第１膜および複数の第２膜を貫通するトレンチを有しており、トレンチ内へリン酸含有処理液が侵入する。第２膜は酸化シリコン膜であってよい。 The dipping step may include an exposure step of exposing at least one silicon nitride film of the substrate to the phosphoric acid-containing treatment liquid in the first tank. In the exposure step, the substrate contains a laminate that alternately has a plurality of first films as at least one silicon nitride film and a plurality of second films made of a material that is less likely to be etched by phosphoric acid than silicon nitride. Good. The laminate has trenches penetrating the plurality of first films and the plurality of second films, and the phosphoric acid-containing treatment liquid penetrates into the trenches. The second film may be a silicon oxide film.
　浸漬工程は、基板が有するタングステン膜を第１槽内のリン酸含有処理液にさらす暴露工程を含んでよい。 The dipping step may include an exposure step of exposing the tungsten film of the substrate to the phosphoric acid-containing treatment liquid in the first tank.
　上昇工程および下降工程において、リン酸含有処理液はバブリングされていなくてよい。浸漬工程において、リン酸含有処理液はガスによってバブリングされていてよい。ガスは不活性ガスであってよい。 The phosphoric acid-containing treatment liquid does not have to be bubbled in the ascending step and the descending step. In the dipping step, the phosphoric acid-containing treatment liquid may be bubbled with a gas. The gas may be an inert gas.
　浸漬工程において、基板の主面は上下方向に平行であってよい。 In the dipping step, the main surface of the substrate may be parallel in the vertical direction.
　本発明によれば、基板の少なくとも一部がリン酸含有処理液の液面を通過して上方へと移動される。このとき、リン酸含有処理液の表面張力に起因して、基板からリン酸含有処理液が効果的に除去される。そしてその後の下降工程によって、リン酸含有処理液が除去された箇所へリン酸含有処理液が再度供給される。これにより、基板に接するリン酸含有処理液のうち、単なる流動だけでは置換されにくい部分も、効果的に置換される。よって、リン酸含有処理液による基板のエッチングの進行を均一化することができる。 According to the present invention, at least a part of the substrate passes through the liquid surface of the phosphoric acid-containing treatment liquid and is moved upward. At this time, the phosphoric acid-containing treatment liquid is effectively removed from the substrate due to the surface tension of the phosphoric acid-containing treatment liquid. Then, by the subsequent lowering step, the phosphoric acid-containing treatment liquid is supplied again to the portion where the phosphoric acid-containing treatment liquid has been removed. As a result, in the phosphoric acid-containing treatment liquid in contact with the substrate, the portion that is difficult to be replaced by mere flow is also effectively replaced. Therefore, the progress of etching of the substrate by the phosphoric acid-containing treatment liquid can be made uniform.
本発明の実施の形態１における基板処理装置の構成を概略的に示す図である。It is a figure which shows schematic structure of the substrate processing apparatus in Embodiment 1 of this invention. 本発明の実施の形態１における基板処理方法の第１の工程を概略的に示す断面図である。It is sectional drawing which shows roughly the 1st step of the substrate processing method in Embodiment 1 of this invention. 本発明の実施の形態１における基板処理方法の第２の工程を概略的に示す断面図である。FIG. 5 is a cross-sectional view schematically showing a second step of the substrate processing method according to the first embodiment of the present invention. 本発明の実施の形態１における基板処理方法の第３の工程を概略的に示す断面図である。It is sectional drawing which shows roughly the 3rd step of the substrate processing method in Embodiment 1 of this invention. 本発明の実施の形態１における基板処理方法の第４の工程を概略的に示す断面図である。FIG. 5 is a cross-sectional view schematically showing a fourth step of the substrate processing method according to the first embodiment of the present invention. 本発明の実施の形態１における基板処理方法の第５の工程を概略的に示す断面図である。It is sectional drawing which shows typically the 5th step of the substrate processing method in Embodiment 1 of this invention. 本発明の実施の形態２における基板処理方法の第１の工程を概略的に示す断面図である。It is sectional drawing which shows roughly the 1st step of the substrate processing method in Embodiment 2 of this invention. 本発明の実施の形態２における基板処理方法の第２の工程を概略的に示す断面図である。It is sectional drawing which shows typically the 2nd step of the substrate processing method in Embodiment 2 of this invention. 本発明の実施の形態２における基板処理方法の第３の工程を概略的に示す断面図である。It is sectional drawing which shows roughly the 3rd process of the substrate processing method in Embodiment 2 of this invention. 本発明の実施の形態２における基板処理方法の第４の工程を概略的に示す断面図である。It is sectional drawing which shows roughly the 4th step of the substrate processing method in Embodiment 2 of this invention. 本発明の実施の形態２における基板処理方法の第５の工程を概略的に示す断面図である。It is sectional drawing which shows typically the 5th step of the substrate processing method in Embodiment 2 of this invention. 本発明の実施の形態２における基板処理方法の第６の工程を概略的に示す断面図である。It is sectional drawing which shows schematic | 6th steps of the substrate processing method in Embodiment 2 of this invention. 本発明の実施の形態２における基板処理方法の第７の工程を概略的に示す断面図である。FIG. 5 is a cross-sectional view schematically showing a seventh step of the substrate processing method according to the second embodiment of the present invention. 本発明の実施の形態２における基板処理方法の第８の工程を概略的に示す断面図である。It is sectional drawing which shows schematic 8 steps of the substrate processing method in Embodiment 2 of this invention. 本発明の実施の形態２における基板処理方法の第９の工程を概略的に示す断面図である。It is sectional drawing which shows schematic 9th steps of the substrate processing method in Embodiment 2 of this invention. 本発明の実施の形態２における基板処理方法の第１０の工程を概略的に示す断面図である。FIG. 5 is a cross-sectional view schematically showing a tenth step of the substrate processing method according to the second embodiment of the present invention. 本発明の実施の形態３における基板処理方法の第１の工程を概略的に示す断面図である。It is sectional drawing which shows roughly the 1st step of the substrate processing method in Embodiment 3 of this invention. 本発明の実施の形態３における基板処理方法の第２の工程を概略的に示す断面図である。It is sectional drawing which shows typically the 2nd step of the substrate processing method in Embodiment 3 of this invention. 本発明の実施の形態３における基板処理方法の第３の工程を概略的に示す断面図である。It is sectional drawing which shows roughly the 3rd step of the substrate processing method in Embodiment 3 of this invention.
　以下、図面に基づいて本発明の実施の形態について説明する。なお、以下の図面において同一または相当する部分には同一の参照番号を付しその説明は繰返さない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings below, the same or corresponding parts are given the same reference number and the explanation is not repeated.
　＜実施の形態１＞
　図１は、本実施の形態１における基板処理装置１００の構成を概略的に示す図である。なお、説明の便宜上、基板処理装置１００によって処理される基板５００と、基板処理装置１００によって用いられるリン酸溶液ＥＴ（リン酸含有処理液）とが、仮想線（２点鎖線）によって示されている。リン酸溶液ＥＴ中には、リン酸に加えてさらに、ひとつまたは複数の材料が溶かされていてもよい。 <Embodiment 1>
FIG. 1 is a diagram schematically showing the configuration of the substrate processing apparatus 100 according to the first embodiment. For convenience of explanation, the substrate 500 processed by the substrate processing apparatus 100 and the phosphoric acid solution ET (phosphoric acid-containing processing liquid) used by the substrate processing apparatus 100 are indicated by virtual lines (two-point chain line). There is. In addition to phosphoric acid, one or more materials may be further dissolved in the phosphoric acid solution ET.
　基板処理装置は、槽１０１（第１槽）と、外槽１０２と、リフター５１（基板保持部）と、アクチュエータ５２（リフター駆動部）と、溶液供給源１１（リン酸含有処理液供給源）と、バルブ１２と、ガス供給源２１と、バルブ２２と、ポンプ１６と、ヒータ１７とを有している。槽１０１は、少なくとも１つの液注入口１１１と、少なくとも１つのガス注入口１１２とを有している。 The substrate processing apparatus includes a tank 101 (first tank), an outer tank 102, a lifter 51 (board holding unit), an actuator 52 (lifter driving unit), and a solution supply source 11 (phosphoric acid-containing processing liquid supply source). A valve 12, a gas supply source 21, a valve 22, a pump 16, and a heater 17. The tank 101 has at least one liquid injection port 111 and at least one gas injection port 112.
　槽１０１は、基板５００を処理するためのリン酸溶液ＥＴを貯留する容器である。槽１０１に貯留されたリン酸溶液ＥＴは液面ＳＦを有する。槽１０１に貯留されたリン酸溶液ＥＴに基板５００が浸漬されることによって、基板５００の処理、具体的にはエッチング処理、が行われる。外槽１０２は、液面ＳＦからオーバーフローしたリン酸溶液ＥＴを貯留する容器である。 The tank 101 is a container for storing the phosphoric acid solution ET for processing the substrate 500. The phosphoric acid solution ET stored in the tank 101 has a liquid level SF. By immersing the substrate 500 in the phosphoric acid solution ET stored in the tank 101, the substrate 500 is processed, specifically, an etching process is performed. The outer tank 102 is a container for storing the phosphoric acid solution ET that overflows from the liquid level SF.
　ポンプ１６およびヒータ１７は、外槽１０２から液注入口１１１への配管経路中に設けられている。これにより、加熱されたリン酸溶液ＥＴが還流される。具体的には、外槽１０２から吸い出されたリン酸溶液ＥＴは、加熱された後、液注入口１１１から槽１０１中へ吐出される。 The pump 16 and the heater 17 are provided in the piping path from the outer tank 102 to the liquid injection port 111. As a result, the heated phosphoric acid solution ET is refluxed. Specifically, the phosphoric acid solution ET sucked out from the outer tank 102 is heated and then discharged from the liquid injection port 111 into the tank 101.
　溶液供給源１１は、バルブ１２による制御に応じて、新たなリン酸溶液（リン酸含有処理液）を槽１０１へ供給する。なお図１においてはリン酸溶液が槽１０１へ直接供給される構成が示されているが、他の構成が用いられてもよい。例えば、リン酸溶液が、上述した還流用の経路と外槽１０２との少なくともいずれかを介して槽１０１へ間接的に供給されてもよい。 The solution supply source 11 supplies a new phosphoric acid solution (phosphoric acid-containing treatment liquid) to the tank 101 according to the control by the valve 12. Although FIG. 1 shows a configuration in which the phosphoric acid solution is directly supplied to the tank 101, other configurations may be used. For example, the phosphoric acid solution may be indirectly supplied to the tank 101 via at least one of the above-mentioned reflux path and the outer tank 102.
　ガス供給源２１は、バルブ２２による制御に応じて、ガスをガス注入口１１２へ供給する。これにより、バルブ２２による制御に応じて、槽１０１に貯留されたリン酸溶液ＥＴ中へのバブリングが実施される。好ましくは、槽１０１に複数のガス注入口１１２が設けられている。 The gas supply source 21 supplies gas to the gas inlet 112 according to the control by the valve 22. As a result, bubbling into the phosphoric acid solution ET stored in the tank 101 is performed according to the control by the valve 22. Preferably, the tank 101 is provided with a plurality of gas inlets 112.
　リフター５１は、少なくとも１つの基板５００を保持する。好ましくは、リフター５１は複数の基板５００を保持し、この場合、バッチ式処理が行なわれることになる。アクチュエータ５２は、リフター５１を上下に変位させる。これにより、上下方向におけるリン酸溶液ＥＴの液面ＳＦの位置を基準として、リフター５１に保持された基板５００の相対位置が変化させられる。よって、基板５００がどの程度の割合でリン酸溶液ＥＴに浸漬されるかが制御される。アクチュエータ５２は、例えば、サーボモータまたはタイミングベルトを有している。 The lifter 51 holds at least one substrate 500. Preferably, the lifter 51 holds a plurality of substrates 500, in which case batch processing will be performed. The actuator 52 displaces the lifter 51 up and down. As a result, the relative position of the substrate 500 held by the lifter 51 can be changed with reference to the position of the liquid level SF of the phosphoric acid solution ET in the vertical direction. Therefore, the rate at which the substrate 500 is immersed in the phosphoric acid solution ET is controlled. The actuator 52 has, for example, a servomotor or a timing belt.
　バルブ２２およびアクチュエータ５２は、制御部（図示せず）からの命令に応じて動作してよい。制御部は、典型的には、電気回路によって構成され、プロセッサおよび記憶装置を有する。プロセッサは、記憶装置に格納されているプログラムを実行することによって、バルブ２２およびアクチュエータ５２への命令を発する。 The valve 22 and the actuator 52 may operate in response to a command from a control unit (not shown). The control unit is typically composed of electrical circuits and includes a processor and a storage device. The processor issues commands to the valve 22 and the actuator 52 by executing a program stored in the storage device.
　図２～図６のそれぞれは、本実施の形態１における、基板処理装置１００（図１）を用いた基板処理方法の第１～第５の工程を概略的に示す断面図である。この基板処理方法により、例えば、基板５００が有する窒化シリコン膜（図２～図６において図示せず）がエッチングされる。 Each of FIGS. 2 to 6 is a cross-sectional view schematically showing the first to fifth steps of the substrate processing method using the substrate processing apparatus 100 (FIG. 1) in the first embodiment. By this substrate processing method, for example, the silicon nitride film (not shown in FIGS. 2 to 6) included in the substrate 500 is etched.
　図２を参照して、槽１０１内にリン酸溶液ＥＴが貯留される。リン酸溶液ＥＴの液面ＳＦの上方に、少なくとも１つ、好ましくは複数、の基板５００が、リフター５１によって保持される。次に、アクチュエータ５２がリフター５１を液面ＳＦへ向けて下降させる（図中、破線矢印参照）。 With reference to FIG. 2, the phosphoric acid solution ET is stored in the tank 101. At least one, preferably a plurality, of substrates 500 are held by the lifter 51 above the liquid level SF of the phosphoric acid solution ET. Next, the actuator 52 lowers the lifter 51 toward the liquid level SF (see the broken line arrow in the figure).
　図３を参照して、リフター５１の下降により、基板５００の少なくとも一部、好ましくは全体、が液面ＳＦよりも下方に配置される。リフター５１の下降中は、リン酸溶液ＥＴはバブリングされていないことが好ましい。 With reference to FIG. 3, by lowering the lifter 51, at least a part, preferably the whole, of the substrate 500 is arranged below the liquid level SF. It is preferable that the phosphoric acid solution ET is not bubbled during the descent of the lifter 51.
　図４を参照して、上述した工程を経ることで、槽１０１内のリン酸溶液ＥＴに基板５００が浸漬される。言い換えれば、浸漬工程が開始される。浸漬工程中は、基板５００の位置は固定されていることが好ましい。浸漬工程において、基板５００の主面ＭＳは上下方向に平行であることが好ましい。言い換えれば、基板５００の厚み方向は水平方向に沿っていることが好ましい。浸漬工程において、リン酸溶液ＥＴはガスによってバブリングされていることが好ましい。言い換えれば、ガス注入口１１２からのガスの供給によってバブルＢＢが発生させられることが好ましい。ガスは、不活性ガスであることが好ましく、例えば窒素ガス（Ｎ２）である。 With reference to FIG. 4, the substrate 500 is immersed in the phosphoric acid solution ET in the tank 101 through the above-mentioned steps. In other words, the dipping process is started. During the dipping step, the position of the substrate 500 is preferably fixed. In the dipping step, the main surface MS of the substrate 500 is preferably parallel in the vertical direction. In other words, the thickness direction of the substrate 500 is preferably along the horizontal direction. In the dipping step, the phosphoric acid solution ET is preferably bubbled with a gas. In other words, it is preferable that the bubble BB is generated by the supply of gas from the gas inlet 112. The gas is preferably an inert gas, for example nitrogen gas (N 2 ).
　図５および図６を参照して、次に、上昇工程が行われる。具体的には、槽１０１内のリン酸溶液ＥＴの液面ＳＦを通過して上方へと、基板５００の少なくとも一部が上昇させられる。上昇工程は、図６に示されているように、槽１０１内のリン酸溶液ＥＴの液面ＳＦを通過して上方へと、基板５００の全体を上昇させることによって行われることが好ましい。リフター５１の上昇工程中は、リン酸溶液ＥＴはバブリングされていないことが好ましい。 With reference to FIGS. 5 and 6, the ascending step is then performed. Specifically, at least a part of the substrate 500 is raised upward through the liquid level SF of the phosphoric acid solution ET in the tank 101. As shown in FIG. 6, the ascending step is preferably performed by ascending the entire substrate 500 upward through the liquid level SF of the phosphoric acid solution ET in the tank 101. It is preferable that the phosphoric acid solution ET is not bubbled during the lifting step of the lifter 51.
　再び図２および図３を参照して、次に、下降工程が行われる。具体的には、槽１０１内のリン酸溶液ＥＴの液面ＳＦを通過して下方へと、基板５００の少なくとも一部、好ましくは全体、が下降させられる。下降工程において、リン酸溶液ＥＴはバブリングされていないことが好ましい。再び図４を参照して、これにより、上述した浸漬工程が再度開始される。再び図５および図６を参照して、次に、上昇工程が再度行われる。このように、下降工程、浸漬工程および上昇工程のセットが１回行われる。この後、これら工程のセットがさらに、少なくとも１回行われることが好ましく、複数回行われることがさらに好ましい。例えば、下降工程、浸漬工程および上昇工程によって各々構成される３回以上のセットが周期的に実施されてよい。 With reference to FIGS. 2 and 3 again, the lowering step is then performed. Specifically, at least a part, preferably the whole, of the substrate 500 is lowered by passing through the liquid level SF of the phosphoric acid solution ET in the tank 101. In the lowering step, the phosphoric acid solution ET is preferably not bubbled. With reference to FIG. 4 again, this initiates the immersion step described above again. With reference to FIGS. 5 and 6 again, the ascending step is then performed again. In this way, the lowering step, the dipping step, and the ascending step are set once. After this, the set of these steps is preferably performed at least once, more preferably a plurality of times. For example, three or more sets each composed of a descending step, a dipping step, and an ascending step may be periodically performed.
　言い換えれば、好ましくは、上昇工程および下降工程のセットが複数回繰り返される。このセットは、１０回以上繰り返されてよい。例えば、このセットは２時間程度の基板処理中に４０～５０回程度繰り返され、この場合、セットが行われる頻度（単位時間当たりの回数）は数分あたり１回である。好ましくは、上昇工程および下降工程のセットを第１頻度で繰り返す第１工程と、この第１工程の後に、上昇工程および下降工程のセットを第２頻度で繰り返す第２工程とが行われ、第２頻度は第１頻度よりも低い。 In other words, preferably, the set of the ascending step and the descending step is repeated a plurality of times. This set may be repeated 10 times or more. For example, this set is repeated about 40 to 50 times during the substrate processing for about 2 hours, and in this case, the frequency of setting (the number of times per unit time) is once every few minutes. Preferably, a first step of repeating the set of the ascending step and the descending step with the first frequency and a second step of repeating the set of the ascending step and the descending step with the second frequency are performed after the first step. The 2nd frequency is lower than the 1st frequency.
　以上により、本実施の形態の基板処理方法が完了する。なお上述した工程の後、必要に応じて、基板５００に対して、水洗工程が行なわれてよい。水洗工程は、槽１０１へ水を供給することによって行なわれてもよく、あるいは、別の槽において行われてもよい。 With the above, the substrate processing method of the present embodiment is completed. After the above-mentioned steps, the substrate 500 may be washed with water, if necessary. The water washing step may be performed by supplying water to the tank 101, or may be performed in another tank.
　本実施の形態によれば、上昇工程（図５および図６）によって、基板５００の少なくとも一部がリン酸溶液ＥＴの液面ＳＦを通過して上方へと移動される。このとき、リン酸溶液ＥＴの表面張力に起因して、基板５００からリン酸溶液ＥＴが効果的に除去される。そしてその後の下降工程（図２および図３参照）によって、リン酸溶液ＥＴが除去された箇所へリン酸溶液ＥＴが再度供給される。これにより、基板５００に接するリン酸溶液ＥＴのうち、単なる流動だけでは置換されにくい部分も、効果的に置換される。よって、リン酸溶液ＥＴによる基板５００のエッチングの進行を均一化することができる。なお、単なる流動だけでは置換されにくい部分の例については、後述する実施の形態３において詳述する。 According to the present embodiment, at least a part of the substrate 500 is moved upward through the liquid level SF of the phosphoric acid solution ET by the ascending step (FIGS. 5 and 6). At this time, the phosphoric acid solution ET is effectively removed from the substrate 500 due to the surface tension of the phosphoric acid solution ET. Then, the phosphoric acid solution ET is supplied again to the portion where the phosphoric acid solution ET has been removed by the subsequent descending step (see FIGS. 2 and 3). As a result, the portion of the phosphoric acid solution ET in contact with the substrate 500 that is difficult to be replaced by mere flow is effectively replaced. Therefore, the progress of etching of the substrate 500 by the phosphoric acid solution ET can be made uniform. An example of a portion that is difficult to be replaced only by a simple flow will be described in detail in the third embodiment described later.
　下降工程は、後述する実施の形態２と異なり本実施の形態においては、図２および図３に示されるように、槽１０１内のリン酸溶液ＥＴの液面ＳＦを通過して下方へと基板５００の少なくとも一部を下降させる工程である。これにより、槽１０１中でのエッチングの進行を、上記のように均一化することができる。 The lowering step is different from the second embodiment described later, and in the present embodiment, as shown in FIGS. 2 and 3, the lowering substrate passes through the liquid level SF of the phosphoric acid solution ET in the tank 101 and downwards. It is a step of lowering at least a part of 500. As a result, the progress of etching in the tank 101 can be made uniform as described above.
　上昇工程は、図６に示されるように、槽１０１内のリン酸溶液ＥＴの液面ＳＦを通過して上方へと、基板５００の全体を上昇させることによって行われることが好ましい。これにより、基板５００からリン酸溶液ＥＴを、より効果的に除去することができる。 As shown in FIG. 6, the ascending step is preferably performed by ascending the entire substrate 500 upward through the liquid level SF of the phosphoric acid solution ET in the tank 101. Thereby, the phosphoric acid solution ET can be removed more effectively from the substrate 500.
　上昇工程（図５および図６参照）および下降工程（図２および図３参照）において、リン酸溶液ＥＴはバブリングされていないことが好ましい。これにより、上昇工程および下降工程においてバブリングに起因して基板５００の姿勢が不安定となることが避けられる。 It is preferable that the phosphoric acid solution ET is not bubbled in the ascending step (see FIGS. 5 and 6) and the descending step (see FIGS. 2 and 3). As a result, it is possible to prevent the posture of the substrate 500 from becoming unstable due to bubbling in the ascending step and the descending step.
　浸漬工程（図４）において、リン酸溶液ＥＴはガスによってバブリングされていることが好ましい。バブリングによって引き起こされるリン酸溶液ＥＴの流れによって、リン酸溶液ＥＴの置換が、より促進される。バブリング用ガスは不活性ガスであることが好ましい。これにより、ガスに起因しての不必要な化学的作用を避けることができる。 In the dipping step (FIG. 4), the phosphoric acid solution ET is preferably bubbled with gas. The flow of phosphate solution ET caused by bubbling further facilitates the substitution of phosphate solution ET. The bubbling gas is preferably an inert gas. This avoids unnecessary chemical action caused by the gas.
　浸漬工程（図４）において、基板５００の主面ＭＳは上下方向に平行であることが好ましい。これにより、主面ＭＳに沿っての基板５００の移動によって、基板５００を上下方向に動かすことができる。よって、主面ＭＳに沿っての基板５００の移動によって、基板５００を槽１０１へ入れたり出したりすることができる。 In the dipping step (FIG. 4), the main surface MS of the substrate 500 is preferably parallel in the vertical direction. As a result, the substrate 500 can be moved in the vertical direction by moving the substrate 500 along the main surface MS. Therefore, the substrate 500 can be moved in and out of the tank 101 by moving the substrate 500 along the main surface MS.
　好ましくは、上昇工程および下降工程のセットを第１頻度で繰り返す第１工程と、この第１工程の後に、上昇工程および下降工程のセットを第２頻度で繰り返す第２工程とが行われ、第２頻度は第１頻度よりも低い。第２頻度に比して第１頻度を高くすることによって、基板処理の初期段階におけるリン酸溶液ＥＴの置換むらの影響を抑制することができる。また第１頻度に比して第２頻度を低くすることによって、上昇工程および下降工程を過度に頻繁に繰り返すことに起因しての処理速度の低下を避けることができる。例えば、窒化シリコン膜をエッチングする基板処理が行われる場合、初期段階においては、エッチングが急速に進行しやすいので、基板５００に接するリン酸溶液ＥＴ中のシリコン濃度も急増しやすい。よって初期段階においては、濃度むらを抑制するために、比較的高い第１頻度で上昇工程および下降工程のセットが行われることが好ましい。一方でその後の段階においては、シリコン濃度の増加は緩やかとなるので、比較的低い第２頻度で上昇工程および下降工程のセットが行われることが好ましい。これにより、リン酸溶液ＥＴが一時的に除去されることに起因しての処理速度の低下を抑制することができる。特に、加熱されたリン酸溶液ＥＴが用いられている場合は、リン酸溶液ＥＴによって加熱された基板５００の温度が上昇工程と下降工程との間で一時的に低下し、これはエッチングの進行速度の低下につながりやすい。第１頻度に比して低い第２頻度を用いることによって、この温度低下による悪影響を抑制することができる。 Preferably, a first step of repeating the set of the ascending step and the descending step with the first frequency and a second step of repeating the set of the ascending step and the descending step with the second frequency are performed after the first step. The 2nd frequency is lower than the 1st frequency. By increasing the first frequency as compared with the second frequency, the influence of uneven replacement of the phosphoric acid solution ET in the initial stage of substrate treatment can be suppressed. Further, by lowering the second frequency as compared with the first frequency, it is possible to avoid a decrease in the processing speed due to the ascending step and the descending step being repeated excessively frequently. For example, when a substrate treatment for etching a silicon nitride film is performed, the etching tends to proceed rapidly in the initial stage, so that the silicon concentration in the phosphoric acid solution ET in contact with the substrate 500 also tends to increase rapidly. Therefore, in the initial stage, it is preferable that the ascending step and the descending step are set at a relatively high first frequency in order to suppress the concentration unevenness. On the other hand, in the subsequent stage, the increase in the silicon concentration becomes gradual, so it is preferable that the ascending step and the descending step are set at a relatively low second frequency. As a result, it is possible to suppress a decrease in the processing speed due to the temporary removal of the phosphoric acid solution ET. In particular, when the heated phosphoric acid solution ET is used, the temperature of the substrate 500 heated by the phosphoric acid solution ET temporarily decreases between the ascending step and the descending step, which is the progress of etching. It tends to slow down. By using the second frequency, which is lower than the first frequency, the adverse effect of this temperature decrease can be suppressed.
　＜実施の形態２＞
　図７～図１６のそれぞれは、本実施の形態２における基板処理方法の第１～第１０の工程を概略的に示す断面図である。本実施の形態において用いられる基板処理装置は、基板処理装置１００の構成に加えてさらに、図示されているように、槽２０１（第２槽）および外槽２０２を有している。槽２０１は、少なくとも１つの液注入口２１１と、少なくとも１つのガス注入口２１２とを有している。槽１０１（図１）にとってと同様に槽２０１にも、図示されていないが、溶液供給源１１と、バルブ１２と、ガス供給源２１と、バルブ２２と、ポンプ１６と、ヒータ１７とが設けられている。 <Embodiment 2>
Each of FIGS. 7 to 16 is a cross-sectional view schematically showing the first to tenth steps of the substrate processing method according to the second embodiment. The substrate processing apparatus used in the present embodiment further includes a tank 201 (second tank) and an outer tank 202 as shown in addition to the configuration of the substrate processing apparatus 100. The tank 201 has at least one liquid injection port 211 and at least one gas injection port 212. Similar to the tank 101 (FIG. 1), the tank 201 is provided with a solution supply source 11, a valve 12, a gas supply source 21, a valve 22, a pump 16, and a heater 17, although not shown. Has been done.
　本実施の形態においては、アクチュエータ５２は、リフター５１を上下に変位させることができるだけでなく、水平方向にも変位させることができる。これにより、リフター５１に保持された基板５００を、槽１０１上の位置から槽２０１上の位置へ変位させることができる。言いかえれば、リフター５１はスライダーとしての機能も有している。 In the present embodiment, the actuator 52 can not only displace the lifter 51 up and down, but also displace it in the horizontal direction. As a result, the substrate 500 held by the lifter 51 can be displaced from the position on the tank 101 to the position on the tank 201. In other words, the lifter 51 also has a function as a slider.
　図７を参照して、槽１０１および槽２０１内にリン酸溶液ＥＴが貯留される。槽１０１におけるリン酸溶液ＥＴの液面ＳＦの上方に、少なくとも１つ、好ましくは複数、の基板５００が、リフター５１によって保持される。次に、アクチュエータ５２がリフター５１を液面ＳＦへ向けて下降させる（図中、破線矢印参照）。 With reference to FIG. 7, the phosphoric acid solution ET is stored in the tank 101 and the tank 201. Above the liquid level SF of the phosphoric acid solution ET in the tank 101, at least one, preferably a plurality of, substrates 500 are held by the lifter 51. Next, the actuator 52 lowers the lifter 51 toward the liquid level SF (see the broken line arrow in the figure).
　図８を参照して、リフター５１の下降により、基板５００の少なくとも一部、好ましくは全体、が液面ＳＦよりも下方に配置される。リフター５１の下降中は、リン酸溶液ＥＴはバブリングされていないことが好ましい。 With reference to FIG. 8, by lowering the lifter 51, at least a part, preferably the whole, of the substrate 500 is arranged below the liquid level SF. It is preferable that the phosphoric acid solution ET is not bubbled during the descent of the lifter 51.
　図９を参照して、上述した工程を経ることで、槽１０１内のリン酸溶液ＥＴに基板５００が浸漬される。言い換えれば、槽１０１における浸漬工程が開始される。浸漬工程中は、基板５００の位置は固定されていることが好ましい。浸漬工程において、基板５００の主面ＭＳは上下方向に平行であることが好ましい。言い換えれば、基板５００の厚み方向は水平方向に沿っていることが好ましい。浸漬工程において、リン酸溶液ＥＴはガスによってバブリングされていることが好ましい。言い換えれば、ガス注入口１１２からのガスの供給によってバブルＢＢが発生させられることが好ましい。ガスは、不活性ガスであることが好ましく、例えばＮ２である。 With reference to FIG. 9, the substrate 500 is immersed in the phosphoric acid solution ET in the tank 101 through the above-mentioned steps. In other words, the dipping step in the tank 101 is started. During the dipping step, the position of the substrate 500 is preferably fixed. In the dipping step, the main surface MS of the substrate 500 is preferably parallel in the vertical direction. In other words, the thickness direction of the substrate 500 is preferably along the horizontal direction. In the dipping step, the phosphoric acid solution ET is preferably bubbled with a gas. In other words, it is preferable that the bubble BB is generated by the supply of gas from the gas inlet 112. The gas is preferably an inert gas, for example N 2 .
　図１０および図１１を参照して、次に、槽１０１における上昇工程が行われる。具体的には、槽１０１内のリン酸溶液ＥＴの液面ＳＦを通過して上方へと、基板５００の少なくとも一部が上昇させられる。上昇工程は、図１１に示されているように、槽１０１内のリン酸溶液ＥＴの液面ＳＦを通過して上方へと、基板５００の全体を上昇させることによって行われることが好ましい。リフター５１の上昇工程中は、リン酸溶液ＥＴはバブリングされていないことが好ましい。 With reference to FIGS. 10 and 11, the ascending step in the tank 101 is then performed. Specifically, at least a part of the substrate 500 is raised upward through the liquid level SF of the phosphoric acid solution ET in the tank 101. As shown in FIG. 11, the ascending step is preferably performed by ascending the entire substrate 500 upward through the liquid level SF of the phosphoric acid solution ET in the tank 101. It is preferable that the phosphoric acid solution ET is not bubbled during the lifting step of the lifter 51.
　図１２を参照して、アクチュエータ５２がリフター５１を、槽１０１の上方の位置から槽２０１の上方の位置へと変位させる（図中、破線矢印参照）。 With reference to FIG. 12, the actuator 52 displaces the lifter 51 from the position above the tank 101 to the position above the tank 201 (see the dashed arrow in the figure).
　図１３を参照して、次に、下降工程が行われる。具体的には、槽２０１内のリン酸溶液ＥＴの液面ＳＦを通過して下方へと、基板５００の少なくとも一部、好ましくは全体、が下降させられる。下降工程において、リン酸溶液ＥＴはバブリングされていないことが好ましい。図１４を参照して、これにより、槽２０１における浸漬工程が開始される。浸漬工程中は、基板５００の位置は固定されていることが好ましい。浸漬工程において、基板５００の主面ＭＳは上下方向に平行であることが好ましい。言い換えれば、基板５００の厚み方向は水平方向に沿っていることが好ましい。浸漬工程において、リン酸溶液ＥＴはガスによってバブリングされていることが好ましい。言い換えれば、ガス注入口２１２からのガスの供給によってバブルＢＢが発生させられることが好ましい。ガスは、不活性ガスであることが好ましく、例えばＮ２である。 With reference to FIG. 13, the lowering step is then performed. Specifically, at least a part, preferably the whole, of the substrate 500 is lowered as it passes through the liquid level SF of the phosphoric acid solution ET in the tank 201. In the lowering step, the phosphoric acid solution ET is preferably not bubbled. With reference to FIG. 14, this initiates the dipping step in tank 201. During the dipping step, the position of the substrate 500 is preferably fixed. In the dipping step, the main surface MS of the substrate 500 is preferably parallel in the vertical direction. In other words, the thickness direction of the substrate 500 is preferably along the horizontal direction. In the dipping step, the phosphoric acid solution ET is preferably bubbled with a gas. In other words, it is preferable that the bubble BB is generated by the supply of gas from the gas inlet 212. The gas is preferably an inert gas, for example N 2 .
　図１５および図１６を参照して、次に、槽２０１における上昇工程が行われる。これにより、本実施の形態の基板処理方法が完了する。 With reference to FIGS. 15 and 16, the ascending step in the tank 201 is then performed. This completes the substrate processing method of the present embodiment.
　なお、上記においては基板処理方法が２つの槽１０１，１０２を用いて行われる場合について説明したが、３つ以上の槽が用いられてもよい。また、槽１０１中のリン酸溶液ＥＴの成分と、槽１０１中のリン酸溶液ＥＴの成分とは、互いに異なっていてもよい。これにより、例えば、リン酸溶液ＥＴによるエッチング速度が、槽１０１において相対的に低速とされ、槽２０１において相対的に高速とされてもよい。 Although the case where the substrate processing method is performed using two tanks 101 and 102 has been described above, three or more tanks may be used. Further, the components of the phosphoric acid solution ET in the tank 101 and the components of the phosphoric acid solution ET in the tank 101 may be different from each other. Thereby, for example, the etching rate by the phosphoric acid solution ET may be relatively low in the tank 101 and relatively high in the tank 201.
　本実施の形態によれば、前述した実施の形態１の場合と同様の理由で、基板５００のエッチングの進行を均一化することができる。さらに、リン酸溶液ＥＴによる処理が、槽１０１中だけでなく第２槽２０１中でも行われる。これにより、リン酸溶液ＥＴによる処理が槽１０１中のみで行われる場合に比して、基板処理時のリン酸溶液ＥＴ中での生成物（例えば、窒化シリコンのエッチング処理時にリン酸溶液ＥＴ中へ生成されるシリコン）の濃度の増大等に起因してのリン酸溶液ＥＴのエッチング能力の低下を抑制することができる。この効果は、使用済みのリン酸溶液ＥＴ中へ新たなリン酸溶液を徐々に混入することによってリン酸溶液ＥＴのエッチング能力を維持する処理が実施されない場合において、特に大きい。 According to the present embodiment, the progress of etching of the substrate 500 can be made uniform for the same reason as in the case of the first embodiment described above. Further, the treatment with the phosphoric acid solution ET is performed not only in the tank 101 but also in the second tank 201. As a result, the product in the phosphoric acid solution ET during the substrate treatment (for example, in the phosphoric acid solution ET during the etching treatment of silicon nitride) is compared with the case where the treatment with the phosphoric acid solution ET is performed only in the tank 101. It is possible to suppress a decrease in the etching ability of the phosphoric acid solution ET due to an increase in the concentration of silicon) produced in the phosphoric acid solution. This effect is particularly large when the treatment for maintaining the etching ability of the phosphoric acid solution ET by gradually mixing a new phosphoric acid solution into the used phosphoric acid solution ET is not performed.
　＜実施の形態３＞
　本実施の形態３においては、前述した実施の形態１における基板処理方法の具体的な適用について説明する。図１７～図１９は、本実施の形態３における基板処理方法の第１～第３の工程を概略的に示す断面図である。 <Embodiment 3>
In the third embodiment, the specific application of the substrate processing method in the first embodiment described above will be described. 17 to 19 are cross-sectional views schematically showing the first to third steps of the substrate processing method according to the third embodiment.
　図１７を参照して、本実施の形態における基板処理方法が適用されることになる基板５００は、少なくとも１つの窒化シリコン膜５０５を有している。具体的には、基板５００は、少なくとも１つの窒化シリコン膜５０５としての複数の犠牲膜５０５（第１膜）と、窒化シリコンに比してリン酸にエッチングされにくい材料からなる複数の構造膜５０３（第２膜）と、を交互に有する積層体を含む。積層体は複数の犠牲膜５０５および複数の構造膜５０３を貫通するトレンチＴＲを有している。トレンチＴＲは、主面ＭＳ上に開口部ＯＰを有しており、基板５００の厚み方向に延びている。構造膜５０３は酸化シリコン膜５０３であることが好ましい。基板５００は、積層体を支持する支持層５０１を有していてよい。支持層は、例えばシリコン層である。 With reference to FIG. 17, the substrate 500 to which the substrate processing method of the present embodiment is applied has at least one silicon nitride film 505. Specifically, the substrate 500 is composed of a plurality of sacrificial films 505 (first film) as at least one silicon nitride film 505, and a plurality of structural films 503 made of a material that is less likely to be etched by phosphoric acid than silicon nitride. (Second film) and a laminated body having alternately. The laminate has a trench TR that penetrates the plurality of sacrificial films 505 and the plurality of structural films 503. The trench TR has an opening OP on the main surface MS and extends in the thickness direction of the substrate 500. The structural film 503 is preferably a silicon oxide film 503. The substrate 500 may have a support layer 501 that supports the laminate. The support layer is, for example, a silicon layer.
　図１８を参照して、次に、前述した実施の形態１で説明した基板処理方法によって、浸漬工程（図４）が行われる。これにより、窒化シリコン膜５０５を槽１０１（図４）内のリン酸溶液ＥＴにさらす暴露工程が行われる。暴露工程の時点で基板５００は、前述したトレンチＴＲを有する積層体を含む。暴露工程によって、開口部ＯＰからトレンチＴＲ内へリン酸溶液ＥＴが侵入する。その結果、トレンチＴＲから水平方向に犠牲膜５０５の各々のエッチングが進行し始める。 With reference to FIG. 18, the immersion step (FIG. 4) is then performed by the substrate processing method described in the first embodiment described above. As a result, the exposure step of exposing the silicon nitride film 505 to the phosphoric acid solution ET in the tank 101 (FIG. 4) is performed. At the time of the exposure step, the substrate 500 includes the laminate having the trench TR described above. The phosphoric acid solution ET penetrates into the trench TR from the opening OP by the exposure step. As a result, each etching of the sacrificial film 505 starts to proceed horizontally from the trench TR.
　このエッチングの進行中、最上層の犠牲膜５０５のエッチング進行箇所Ｐ１に比して、最下層の犠牲膜５０５のエッチング進行箇所Ｐ２においては、リン酸溶液ＥＴが、単なる流動だけでは置換されにくい。よって、置換を促進するための処理が単なる流動のみであったと仮定すると、最上層の犠牲膜５０５に比して、最下層の犠牲膜５０５のエッチングはかなり進行しにくく、その結果、エッチングの進行の不均一性が大きくなりやすい。 During the progress of this etching, the phosphoric acid solution ET is less likely to be replaced by the mere flow at the etching progress portion P2 of the sacrifice film 505 of the lowermost layer as compared with the etching progress portion P1 of the sacrifice film 505 of the uppermost layer. Therefore, assuming that the treatment for promoting the substitution is merely flow, the etching of the sacrificial film 505 of the lowermost layer is considerably less likely to proceed than that of the sacrificial film 505 of the uppermost layer, and as a result, the etching progresses. Non-uniformity tends to increase.
　本実施の形態においては、エッチング進行箇所Ｐ２であってもリン酸溶液ＥＴが十分に置換されるようにする目的で、前述した実施の形態１で説明した基板処理方法が用いられる。この基板処理方法が有する上昇工程（図５および図６）によって、トレンチＴＲの開口部ＯＰは、リン酸溶液ＥＴの液面ＳＦの下方から上方へと移動される。このとき、リン酸溶液ＥＴの表面張力に起因して、トレンチＴＲと、そこから水平方向に延びる、犠牲膜５０５のエッチングによって形成された空洞部ＧＰとから、リン酸溶液ＥＴを引き抜く作用が生じる。その結果、箇所Ｐ２においても、リン酸溶液ＥＴを引き抜く作用が加わる。次に、下降工程（図２および図３）によって、トレンチＴＲの開口部ＯＰは、リン酸溶液ＥＴの液面ＳＦの上方から下方へと移動される。このとき箇所Ｐ２においても、前述した上昇工程によってリン酸溶液ＥＴを引き抜く作用が加わっていたために、新たなリン酸溶液ＥＴが侵入しやすくなる。よって箇所Ｐ２においてもリン酸溶液ＥＴが十分に置換される。 In the present embodiment, the substrate processing method described in the above-described first embodiment is used for the purpose of sufficiently replacing the phosphoric acid solution ET even at the etching progress portion P2. By the ascending step (FIGS. 5 and 6) of this substrate processing method, the opening OP of the trench TR is moved from below to above the liquid level SF of the phosphoric acid solution ET. At this time, due to the surface tension of the phosphoric acid solution ET, the action of pulling out the phosphoric acid solution ET from the trench TR and the cavity GP formed by etching the sacrificial film 505 extending in the horizontal direction from the trench TR occurs. .. As a result, the action of pulling out the phosphoric acid solution ET is also added to the portion P2. Next, the opening OP of the trench TR is moved from above to below the liquid level SF of the phosphoric acid solution ET by the descending step (FIGS. 2 and 3). At this time, also in the portion P2, since the action of pulling out the phosphoric acid solution ET is added by the above-mentioned ascending step, a new phosphoric acid solution ET easily invades. Therefore, the phosphoric acid solution ET is sufficiently substituted at the location P2 as well.
　図１９を参照して、上記基板処理によって、犠牲膜５０５（図１７）が空洞部ＧＰへと変化させられる。このような処理を施された基板５００は、３次元メモリデバイス（例えば、３次元ＮＡＮＤメモリデバイス）を製造するための基板として用いられ得る。 With reference to FIG. 19, the sacrificial film 505 (FIG. 17) is changed to the cavity GP by the substrate treatment. The substrate 500 subjected to such processing can be used as a substrate for manufacturing a three-dimensional memory device (for example, a three-dimensional NAND memory device).
　本実施の形態によれば、浸漬工程（図４）は、窒化シリコン膜５０５（図１７）を槽１０１内のリン酸溶液ＥＴにさらす暴露工程を含む。これにより、窒化シリコン膜５０５をエッチングすることができる。暴露工程において、トレンチＴＲ内へリン酸溶液ＥＴが侵入する。この場合、一般的に言えば、トレンチＴＲにおける深い箇所Ｐ２（図１８）の近傍では、浅い箇所Ｐ１（図１８）の近傍に比して、リン酸溶液ＥＴが置換されにくい。これにより、浅く位置する窒化シリコン膜５０５に比して、深く位置する窒化シリコン膜５０５がエッチングされにくくなりやすい。よって、エッチングの進行の不均一性が大きくなりやすい。窒化シリコン膜５０５の層数が増加するほどトレンチＴＲの深さが増大するので、上記問題はより深刻となり得る。本実施の形態によれば、トレンチＴＲにおける深い箇所Ｐ２（図１８）の近傍においても、実施の形態１において説明した理由により、リン酸溶液ＥＴが効果的に置換される。よって、基板５００のエッチングの進行を均一化することができる。 According to the present embodiment, the immersion step (FIG. 4) includes an exposure step of exposing the silicon nitride film 505 (FIG. 17) to the phosphoric acid solution ET in the tank 101. As a result, the silicon nitride film 505 can be etched. In the exposure step, the phosphoric acid solution ET invades the trench TR. In this case, generally speaking, the phosphoric acid solution ET is less likely to be replaced in the vicinity of the deep portion P2 (FIG. 18) in the trench TR than in the vicinity of the shallow portion P1 (FIG. 18). As a result, the silicon nitride film 505 located deeper is less likely to be etched than the silicon nitride film 505 located shallower. Therefore, the non-uniformity of the etching progress tends to increase. As the number of layers of the silicon nitride film 505 increases, the depth of the trench TR increases, so that the above problem can become more serious. According to the present embodiment, the phosphoric acid solution ET is effectively replaced even in the vicinity of the deep portion P2 (FIG. 18) in the trench TR for the reason described in the first embodiment. Therefore, the progress of etching of the substrate 500 can be made uniform.
　構造膜５０３は酸化シリコン膜５０３であることが好ましい。これにより、リン酸溶液ＥＴに対しての構造膜５０３の耐エッチング性を十分に確保することができる。 The structural film 503 is preferably a silicon oxide film 503. As a result, the etching resistance of the structural film 503 with respect to the phosphoric acid solution ET can be sufficiently ensured.
　なお上記においては、図１７～図１９の工程を行うために、前述した実施の形態１における基板処理方法が用いられる場合について説明したが、代わりに、前述した実施の形態２における基板処理方法が用いられてもよい。 In the above, the case where the substrate processing method in the above-described first embodiment is used to perform the steps of FIGS. 17 to 19 has been described, but instead, the substrate processing method in the above-described second embodiment is used. It may be used.
　＜実施の形態４＞
　上記実施の形態１～３においては、リン酸溶液ＥＴ（リン酸含有処理液）を用いて窒化シリコン膜がエッチングされる場合について説明した。しかしながら、エッチングされる膜は窒化シリコンからなるものに限定されるわけではなく、本実施の形態においてはタングステンからなる。言い換えれば、本実施の形態においては、浸漬工程（例えば図４）は、基板５００が有するタングステン膜を槽１０１内のリン酸溶液ＥＴにさらす暴露工程を含む。この場合、リン酸含有処理液としては、単なるリン酸溶液ではなく、リン酸に加えて少なくとも１つの酸を含む混酸が好ましく、例えば、リン酸、酢酸および硝酸を含む混酸が好ましい。本実施の形態によれば、タングステン膜のエッチングにおいて、実施の形態１～３の場合とほぼ同様の効果が得られる。 <Embodiment 4>
In the first to third embodiments, the case where the silicon nitride film is etched by using the phosphoric acid solution ET (phosphoric acid-containing treatment liquid) has been described. However, the film to be etched is not limited to that made of silicon nitride, and in the present embodiment, it is made of tungsten. In other words, in the present embodiment, the dipping step (for example, FIG. 4) includes an exposure step of exposing the tungsten film of the substrate 500 to the phosphoric acid solution ET in the tank 101. In this case, the phosphoric acid-containing treatment liquid is not a simple phosphoric acid solution, but a mixed acid containing at least one acid in addition to phosphoric acid is preferable, and for example, a mixed acid containing phosphoric acid, acetic acid and nitric acid is preferable. According to the present embodiment, in etching the tungsten film, substantially the same effect as in the cases of the first to third embodiments can be obtained.
　この発明は詳細に説明されたが、上記の説明は、すべての局面において、例示であって、この発明がそれに限定されるものではない。例示されていない無数の変形例が、この発明の範囲から外れることなく想定され得るものと解される。上記各実施形態および各変形例で説明した各構成は、相互に矛盾しない限り適宜組み合わせたり、省略したりすることができる。 Although the present invention has been described in detail, the above description is exemplary in all aspects, and the invention is not limited thereto. It is understood that a myriad of variations not illustrated can be envisioned without departing from the scope of the invention. The configurations described in the above embodiments and the modifications can be appropriately combined or omitted as long as they do not conflict with each other.
　ＧＰ　空洞部
　ＥＴ　リン酸溶液（リン酸含有処理液）
　ＳＦ　液面
　ＯＰ　開口部
　ＭＳ　主面
　ＴＲ　トレンチ
　１１　溶液供給源
　１２，２２　バルブ
　１６　ポンプ
　１７　ヒータ
　２１　ガス供給源
　５１　リフター
　５２　アクチュエータ
　１００　基板処理装置
　１０１　槽（第１槽）
　１０２，２０２　外槽
　２０１　槽（第２槽）
　１１１，２１１　液注入口
　１１２，２１２　ガス注入口
　５００　基板
　５０１　支持層
　５０３　酸化シリコン膜（構造膜）
　５０５　窒化シリコン膜（犠牲膜） GP cavity ET phosphoric acid solution (phosphoric acid-containing treatment solution)
SF Liquid level OP Opening MS Main surface TR Trench 11 Solution supply source 12, 22 Valve 16 Pump 17 Heater 21 Gas supply source 51 Lifter 52 Actuator 100 Board processing device 101 Tank (1st tank)
102, 202 Outer tank 201 tank (second tank)
111,211 Liquid injection port 112,212 Gas injection port 500 Substrate 501 Support layer 503 Silicon oxide film (structural film)
505 Silicon Nitride Membrane (Sacrifice Membrane)

Claims (13)

  1. 　第１槽内のリン酸含有処理液に基板を浸漬する浸漬工程と、
    　前記浸漬工程の後に、前記第１槽内のリン酸含有処理液の液面を通過して上方へと、前記基板の少なくとも一部を上昇させる上昇工程と、
    　前記上昇工程の後に、前記第１槽内または前記第１槽と異なる第２槽内のリン酸含有処理液の液面を通過して下方へと前記基板の少なくとも一部を下降させる下降工程と、
    を備える基板処理方法。     A dipping step of immersing the substrate in the phosphoric acid-containing treatment liquid in the first tank, and
    After the dipping step, an ascending step of raising at least a part of the substrate by passing through the liquid surface of the phosphoric acid-containing treatment liquid in the first tank and upward.
    After the ascending step, there is a descending step of lowering at least a part of the substrate by passing through the liquid surface of the phosphoric acid-containing treatment liquid in the first tank or in a second tank different from the first tank. ,
    Substrate processing method comprising.
  2. 　前記下降工程は、前記第１槽内のリン酸含有処理液の液面を通過して下方へと前記基板の少なくとも一部を下降させる工程である、請求項１に記載の基板処理方法。 The substrate processing method according to claim 1, wherein the lowering step is a step of lowering at least a part of the substrate downward after passing through the liquid surface of the phosphoric acid-containing processing liquid in the first tank.
  3. 　前記下降工程は、前記第２槽内のリン酸含有処理液の液面を通過して下方へと前記基板の少なくとも一部を下降させる工程である、請求項１に記載の基板処理方法。 The substrate processing method according to claim 1, wherein the lowering step is a step of lowering at least a part of the substrate downward after passing through the liquid surface of the phosphoric acid-containing processing liquid in the second tank.
  4. 　前記上昇工程は、前記第１槽内のリン酸含有処理液の液面を通過して上方へと、前記基板の全体を上昇させることによって行われる、請求項１から３のいずれか１項に記載の基板処理方法。 The ascending step is carried out by ascending the entire substrate by passing through the liquid surface of the phosphoric acid-containing treatment liquid in the first tank and upward, according to any one of claims 1 to 3. The substrate processing method described.
  5. 　前記浸漬工程は、前記基板が有する少なくとも１つの窒化シリコン膜を前記第１槽内のリン酸含有処理液にさらす暴露工程を含む、請求項１から４のいずれか１項に記載の基板処理方法。 The substrate treatment method according to any one of claims 1 to 4, wherein the dipping step includes an exposure step of exposing at least one silicon nitride film of the substrate to a phosphoric acid-containing treatment liquid in the first tank. ..
  6. 　前記暴露工程において、前記基板は前記少なくとも１つの窒化シリコン膜としての複数の第１膜と窒化シリコンに比してリン酸にエッチングされにくい材料からなる複数の第２膜とを交互に有する積層体を含み、前記積層体は前記複数の第１膜および前記複数の第２膜を貫通するトレンチを有しており、前記トレンチ内へ前記リン酸含有処理液が侵入する、請求項５に記載の基板処理方法。 In the exposure step, the substrate is a laminate having a plurality of first films as the at least one silicon nitride film and a plurality of second films made of a material that is less likely to be etched by phosphoric acid than silicon nitride. 5. The phosphoric acid-containing treatment liquid according to claim 5, wherein the laminate has trenches penetrating the plurality of first films and the plurality of second films, and the phosphoric acid-containing treatment liquid penetrates into the trenches. Substrate processing method.
  7. 　前記第２膜は酸化シリコン膜である、請求項６に記載の基板処理方法。 The substrate processing method according to claim 6, wherein the second film is a silicon oxide film.
  8. 　前記浸漬工程は、前記基板が有するタングステン膜を前記第１槽内のリン酸含有処理液にさらす暴露工程を含む、請求項１から４のいずれか１項に記載の基板処理方法。 The substrate treatment method according to any one of claims 1 to 4, wherein the dipping step includes an exposure step of exposing the tungsten film of the substrate to the phosphoric acid-containing treatment liquid in the first tank.
  9. 　前記上昇工程および前記下降工程において、前記リン酸含有処理液はバブリングされていない、請求項１から８のいずれか１項に記載の基板処理方法。 The substrate treatment method according to any one of claims 1 to 8, wherein the phosphoric acid-containing treatment liquid is not bubbled in the ascending step and the descending step.
  10. 　前記浸漬工程において、前記リン酸含有処理液はガスによってバブリングされている、請求項１から９のいずれか１項に記載の基板処理方法。 The substrate treatment method according to any one of claims 1 to 9, wherein in the dipping step, the phosphoric acid-containing treatment liquid is bubbled with a gas.
  11. 　前記ガスは不活性ガスである、請求項１０に記載の基板処理方法。 The substrate processing method according to claim 10, wherein the gas is an inert gas.
  12. 　前記浸漬工程において、前記基板の主面は上下方向に平行である、請求項１から１１のいずれか１項に記載の基板処理方法。 The substrate processing method according to any one of claims 1 to 11, wherein in the dipping step, the main surface of the substrate is parallel in the vertical direction.
  13. 　前記上昇工程および前記下降工程のセットを第１頻度で繰り返す第１工程と、
    　前記第１工程の後に、前記上昇工程および前記下降工程のセットを、前記第１頻度よりも低い第２頻度で繰り返す第２工程と、
    が行われる、請求項１から１２のいずれか１項に記載の基板処理方法。     The first step of repeating the set of the ascending step and the descending step at the first frequency, and
    After the first step, a second step in which the set of the ascending step and the descending step is repeated at a second frequency lower than the first frequency, and
    The substrate processing method according to any one of claims 1 to 12, wherein the method is carried out.
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