JP2017216478A - Substrate processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate processing device operable to perform an etching process, and to more efficiently recover phosphoric acid which can be fed back to the etching process while avoiding using a large facility as far as possible.SOLUTION: A substrate processing device is arranged to process a silicon substrate with a nitride film formed therein by an etchant containing phosphoric acid. The substrate processing device comprises: an etchant-supplying mechanism 34 for supplying the etchant to a surface of the substrate turned around by a substrate spin mechanism 32 provided in a process chamber 31; a liquid reservoir part 33 provided in the process chamber 31 for storing the etchant after use; a hydrofluoric acid-supplying mechanism 36 for supplying a hydrofluoric acid solution to the liquid reservoir part; and a phosphoric acid-collecting part (having pumps 38, 52 and a phosphoric acid-collecting tank 50) for feeding phosphoric acid recovered in the liquid reservoir part back into an etchant to be used by the etchant-supplying mechanism.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a substrate processing apparatus for processing a silicon substrate on which a nitride film is formed with an etching solution containing phosphoric acid.

Conventionally, a substrate processing method has been proposed in which a silicon semiconductor wafer (substrate) on which a nitride film (Si ₃ N ₄ ) and an oxide film (SiO ₂ ) are formed is processed with an etching solution containing phosphoric acid (H ₃ PO ₄ ). (See Patent Document 1). In this substrate processing method, a plurality of semiconductor wafers are put into an etching solution containing phosphoric acid (H ₃ PO ₄ ) stored in an etching tank, and etching processing is performed on each of the plurality of semiconductor wafers at once. Is called. In this etching process, phosphoric acid in the etching solution acts as a catalyst to remove the nitride film (Si ₃ N ₄ ) of the semiconductor wafer.

Then, the used etching solution remaining in the etching processing tank after the etching process is performed is transferred to the processing tank of the regenerator through the receiving tank. An appropriate amount of hydrofluoric acid solution (HF) is added to the amount of the used etching solution in the processing tank in which the used etching solution is stored. In the treatment tank, a used etching solution containing a nitride-based component removed by the etching treatment and a hydrofluoric acid solution (HF) are mixed and reacted in a relatively high temperature environment. Phosphoric acid (H ₃ PO ₄ ) is regenerated. This regenerated phosphoric acid (H ₃ PO ₄ ) is returned to the etching solution to be used for the etching process.

  According to such a substrate processing method, phosphoric acid is regenerated from the used etching solution remaining after the etching treatment, and the phosphoric acid is returned to the etching solution to be used for the etching treatment. However, the etching process for the semiconductor wafer for removing the nitride film can be continued.

Japanese Patent No. 4424517

  However, in the above-described substrate processing method, a large etching tank is required for performing etching processing on many substrates at once, and the amount is large enough to perform etching processing on such many substrates at once. Since an appropriate amount of hydrofluoric acid solution is added to the processing tank and the used etching liquid is reacted with the hydrofluoric acid solution under a relatively high temperature environment. Therefore, a large amount of used etching solution and a large amount of equipment for maintaining a large amount of hydrofluoric acid solution in a predetermined temperature environment become large. In addition, although the amount of phosphoric acid regenerated at one time is increased, it is relatively long until a large amount of the entire used etching solution and the entire hydrofluoric acid solution are mixed in the treatment tank so that they can react efficiently. It takes time, and it cannot be said that phosphoric acid can be efficiently regenerated.

  The present invention has been made in view of such circumstances, and substrate processing that can more efficiently regenerate phosphoric acid that can be returned to the etching process together with the etching process without using as large an equipment as possible. A device is provided.

  A substrate processing apparatus according to the present invention is a substrate processing apparatus for processing a silicon substrate having a nitride film formed thereon using an etching solution containing phosphoric acid, and is provided in a processing chamber and the processing chamber, A substrate spin mechanism that holds and rotates the substrate, an etchant supply mechanism that supplies the etchant to the surface of the substrate that is rotated by the substrate spin mechanism, and the substrate that is provided and rotated in the processing chamber A liquid reservoir for storing used etching liquid obtained after the etching liquid supplied to the surface of the substrate is scattered from the surface of the substrate, a hydrofluoric acid supply mechanism for supplying a hydrofluoric acid solution to the liquid reservoir, and The etchant used in the etching solution supply mechanism is phosphoric acid regenerated by mixing the used etching solution and the hydrofluoric acid solution in the liquid reservoir. A configuration having a phosphoric acid recovery unit for returning the liquid, the.

  According to the substrate processing apparatus of the present invention, phosphoric acid that can be returned to the etching process can be more efficiently regenerated together with the etching process without using as large an equipment as possible.

1 is a diagram showing a basic configuration of a substrate processing apparatus according to a first embodiment of the present invention. It is a figure which shows the spin processing unit (etching process part) in the state which is performing the etching process of a semiconductor wafer in the substrate processing apparatus shown in FIG. It is a figure which shows the spin processing unit of the state which is performing the rinse process of the semiconductor wafer after an etching process in the substrate processing apparatus shown in FIG. In the substrate processing apparatus shown in FIG. 1, it is a figure which shows the spin processing unit (phosphoric acid reproduction | regeneration part) which is performing the process which makes the semiconductor wafer withdraw and regenerates phosphoric acid from used etching liquid. In the substrate processing apparatus shown in FIG. 1, it is a figure which shows the spin processing unit (etching process part, phosphoric acid reproduction | regeneration part) of the state which is performing the process which reproduces | regenerates phosphoric acid from used etching liquid with the etching process of a semiconductor wafer. . It is a figure which shows the structure of the principal part in the substrate processing apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structure of the principal part in the substrate processing apparatus which concerns on the 3rd Embodiment of this invention. It is a figure which shows the structure of the principal part in the substrate processing apparatus which concerns on the 4th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The substrate processing apparatus according to the first embodiment of the present invention is configured as shown in FIG.

In FIG. 1, the substrate processing apparatus includes an etching solution generation tank 10, an etching solution storage tank 20, a spin processing unit 30 (etching processing unit, phosphoric acid regeneration unit), and a phosphoric acid recovery tank 50 (phosphoric acid recovery unit). doing. Further, the substrate processing apparatus has a phosphoric acid supply unit 12, a water supply unit 13, and a silica supply unit 14. The phosphoric acid supply unit 12 uses a phosphoric acid solution (H ₃ PO ₄ ) having a predetermined concentration, the water supply unit 13 uses pure water (H ₂ O), and the silica supply unit 14 uses colloidal silica (SiO ₂ ). It supplies to the production tank 10. The etching solution generation tank 10 is provided with a heater unit 11. In the etching solution generation tank 10, phosphoric acid solution (H ₃ PO ₄ ), pure water (H ₂ O), and colloidal silica (SiO ₂ ) supplied in appropriate amounts from the phosphoric acid supply unit 12, the water supply unit 13, and the silica supply unit 14, respectively. ₂ ) is mixed and maintained at a predetermined temperature by heating by the heater unit 11. Under a predetermined temperature environment, phosphoric acid solution (H ₃ PO ₄ ), pure water (H ₂ O) and colloidal silica (SiO ₂ ) are mixed to produce an etching solution containing phosphoric acid and silicon components. .

A suitable amount of colloidal silica (SiO ₂ ) is added to the etching solution (phosphoric acid solution) from the silica supply unit 14 to adjust the silicon concentration in the etching solution, thereby nitriding formed on the semiconductor wafer to be etched. The selection ratio between the film (Si ₃ N ₄ ) and the oxide film (SiO ₂ ) is maintained within a predetermined range.

A circulation path is provided for the etching solution generation tank 10, and a pump 15, a switching valve 16, and a concentration detector 17 are provided in the circulation path. The circulation path is further provided with a heater (not shown). The pump 15 operates the switching valve 16 and the concentration detector 17 while the etching solution in the etching solution generation tank 10 is maintained at a predetermined temperature. And returned to the etching solution generation tank 10. By such circulation of the etching solution, the phosphoric acid solution (H ₃ PO ₄ ), pure water (H ₂ O), and colloidal silica (SiO ₂ ) are stirred and mixed in the etching solution generation tank 10. Further, based on the concentration detection information by the concentration detector 17 provided in the circulation path, the management control device 100 monitors the phosphoric acid concentration in the generated etching solution. The switching valve 16 switches between the circulation path and the path from the etching solution generation tank 10 to the etching solution storage tank 20. By the operation of the pump 15 in the state switched to the path on the etching solution storage tank 20 side by the switching valve 16, the etching solution generated in the etching solution generation tank 10 is supplied to the etching solution storage tank 20 and stored.

  The etching solution storage tank 20 is provided with a heater unit 21, and the etching solution supplied and stored from the etching solution generation tank 10 is maintained at a predetermined temperature. A circulation path is provided for the etching solution storage tank 20. In this circulation path, an on-off valve 22a, a pump 23, a flow meter 24, a switching valve 25, an on-off valve 22b, and a cooler 26 are provided. Although not shown, a heater is provided in a path portion between the pump 23 and the switching valve 25 in the circulation path. The etching liquid stored while being maintained at a predetermined temperature in the etching liquid storage tank 20 with the on-off valves 22a and 22b being opened is circulated through the circulation path (flow meter 24, switching valve 25, cooler) by the operation of the pump 23. 26) and returned to the etching solution storage tank 20. By such circulation of the etching solution, the temperature and concentration of the etching solution stored in the etching solution storage tank 20 are adjusted to certain conditions. The switching valve 25 switches between the circulation path and the path from the etching solution storage tank 20 to the spin processing unit 30. The etching solution stored in the etching solution storage tank 20 is supplied to the spin processing unit 30 by the operation of the pump 23 in a state in which the path is switched to the spin processing unit 30 side by the switching valve 25.

  The spin processing unit 30 (etching processing unit, phosphoric acid regeneration unit) has a processing chamber 31, and a substrate spin mechanism 32 that rotates the semiconductor wafer W is provided in the processing chamber 31 and faces the substrate spin mechanism 32. An etching solution jet nozzle 34 (etching solution supply mechanism), a rinse solution jet nozzle 35 and a hydrofluoric acid jet nozzle 36 are provided. Further, a separate cup mechanism 33 (liquid reservoir) is provided in the processing chamber 31 so as to be disposed around the substrate spin mechanism 32. The separate cup mechanism 33 has an inner liquid reservoir cup 33c and an outer liquid reservoir cup 33a disposed on the outer side, and a separator 33b is provided at the boundary between the inner liquid reservoir cup 33c and the outer liquid reservoir cup 33a. . The separator 33b moves up and down within a predetermined range by an actuator (not shown). The etching solution ejection nozzle 34 is connected to a path extending from the etching solution storage tank 20 described above to the spin processing unit 30 side via the switching valve 25. Further, the substrate processing apparatus has a rinsing liquid supply unit 41 and a hydrofluoric acid supply unit 42, and a rinsing liquid (for example, pure water) is supplied from the rinsing liquid supply unit 41 to the rinsing liquid ejection nozzle 35, and the hydrofluoric acid A hydrofluoric acid solution (HF) having a predetermined concentration is supplied from the supply unit 42 to the hydrofluoric acid ejection nozzle 36 (hydrofluoric acid supply mechanism).

  A path extending from the inner liquid reservoir cup 33 c reaches the phosphoric acid recovery tank 50 via the on-off valve 37 a and the pump 38. Further, a path extending from the outer liquid reservoir cup 33a reaches a waste liquid tank (not shown) via the on-off valve 37b.

The phosphoric acid solution (H ₃ PO ₄ ) accumulated in the inner liquid reservoir cup 33c of the spin processing unit 30 (phosphoric acid regeneration unit) by the phosphoric acid regeneration process as described later is passed through the on-off valve 37a by the operation of the pump 38. To the phosphoric acid recovery tank 50. The phosphoric acid recovery tank 50 is provided with a heater unit 51, and the phosphoric acid solution stored in the phosphoric acid recovery tank 50 is maintained at a predetermined temperature. A path extends from the phosphoric acid recovery tank 50 to the etching liquid generation tank 10 via the pump 52, and the operation of the pump 52 causes the phosphoric acid solution to pass from the phosphoric acid recovery tank 50 through the path to the etching liquid generation tank 10. Returned.

  In addition to the management of the temperature, flow rate, concentration, etc. of the etching solution as described above, the operation of each pump, various valves, each switching valve, various heaters, the operation of the spin processing unit 30 and the semiconductor wafer W with respect to the spin processing unit 30 The operation of each part such as a mechanism for supplying and discharging is controlled by the management control device 100.

  In the substrate processing apparatus described above, processing on the semiconductor wafer W is performed as follows under management and control by the management control apparatus 100.

The etching solution generated by mixing the phosphoric acid solution (H ₃ PO ₄ ), pure water (H ₂ O), and colloidal silica (SiO ₂ ) in the etching solution generation tank 10 has a high temperature (for example, about 160 ° C.). It is moved to the etching solution storage tank 20 at a predetermined timing while being adjusted. Thereby, the etching solution storage tank 20 is always in a state where the etching solution is stored. The etching solution stored in the etching solution storage tank 20 is adjusted to a high temperature (for example, about 160 ° C.), and the etching solution adjusted to the high temperature is supplied to the spin processing unit 30.

  In the spin processing unit 30 (processing chamber 31), the semiconductor wafers W are supplied one by one, and the supplied semiconductor wafers W are etched. Specifically, as shown in FIG. 2, the supplied semiconductor wafer W is set in the substrate spin mechanism 32, and the semiconductor wafer W is rotated by the substrate spin mechanism 32. While the semiconductor wafer W is rotating, the etching liquid adjusted to a high temperature (for example, about 160 ° C.) supplied from the etching liquid storage tank 20 is ejected from the etching liquid ejection nozzle 34. The etching liquid ejected from the etching liquid ejection nozzle 34 is given to the surface of the rotating semiconductor wafer W, and the semiconductor wafer W is etched.

In the etching process, a high-temperature etching solution (containing phosphoric acid H ₃ PO ₄ , colloidal silica SiO ₂ , H ₂ O) acts on the semiconductor wafer W, and water vapor (H ₂ O) in the presence of the phosphoric acid solution. a nitride film (Si ₃ N ₄₎ and reacts, nitride film (Si ₃ N ₄₎ is removed ammonium phosphate ^{_{([NH 4 +] 3 [}} PO 4 3-]) and dihydrogen silicate (H ₂ SiO ₃ ) is deposited. Then, an etching solution used for the etching treatment, that is, a used etching solution LETC (ammonium phosphate ([NH ₄ ⁺ ] ₃ [PO ₄ ^3- ]) and dihydrogen silicate (H ₂ SiO ₃ ) is included. ) Is scattered by the rotation of the semiconductor wafer W, and the scattered etching solution LETC is led to the inner liquid storage cup 33c by the separator 33b adjusted to the raised position and stored.

  When the etching process for one semiconductor wafer W is completed in this way, the jet of the etchant from the etchant jet nozzle 34 is stopped, and the separator 33b is adjusted to the lowered position as shown in FIG. The rinsing liquid (for example, pure water) supplied from the rinsing liquid supply unit 41 is ejected from the rinsing liquid ejection nozzle 35. The surface of the rotating semiconductor wafer W is cleaned by the rinse liquid ejected from the rinse liquid ejection nozzle 35. The rinsing liquid that cleans and scatters the semiconductor wafer W that rotates at high speed by the substrate spin mechanism 32 has already accumulated in the inner liquid reservoir cup 33a, beyond the inner liquid reservoir cup 33c, and in the inner liquid reservoir cup 33c. It is separated and recovered from the etchant LETC.

  When the rinsing process of the semiconductor wafer W is completed, the rinsing liquid is not ejected from the rinsing liquid ejection nozzle 35, and the semiconductor wafer W is withdrawn from the processing chamber 31 through a process such as drying. Then, the processing chamber 31 is in a state where the used etching liquid LETC for processing one semiconductor wafer W is stored in the inner liquid storage cup 33c.

  Thereafter, as shown in FIG. 4, an appropriate amount of hydrofluoric acid solution (HF) is added to the amount of the used etching solution LETC for processing one semiconductor wafer stored in the inner liquid storage cup 33c. Supplied from the supply unit 42 and ejected from the hydrofluoric acid ejection nozzle 36. The amount of the hydrofluoric acid solution (HF) supplied to the used etching solution LETC for processing the one semiconductor wafer W is determined in advance by experiments or the like.

The hydrofluoric acid solution (HF) ejected from the hydrofluoric acid ejection nozzle 36 is sprayed in the inner liquid reservoir cup 33c in which a high-temperature (for example, about 160 ° C.) used etching solution LETC is stored and becomes a high-temperature environment. Depending on the high temperature environment, a part or all of the steam is provided. In the inner liquid storage cup 33c, a used etching solution LETC (containing ammonium phosphate ([NH ₄ ⁺ ] ₃ [PO ₄ ^3- ]) and dihydrogen silicate (H ₂ SiO ₃ )) and a hydrofluoric acid solution (HF ) Are mixed and reacted under a predetermined high-temperature environment, and the fluoride component is diffused (it is emitted in a gaseous state) to regenerate phosphoric acid (H ₃ PO ₄ ) as a solution.

As described above, the phosphoric acid solution (H ₃ PO ₄ ) regenerated in the inner liquid storage cup 33c of the spin processing unit 30 (processing chamber 31) is pumped with the open / close valve 37a open (see FIG. 1). Is operated, the phosphoric acid recovery tank 50 is supplied. The above-described regeneration process of the phosphoric acid solution (H ₃ PO ₄ ) and the transfer of the phosphoric acid solution from the spin processing unit 30 (inner liquid reservoir cup 33 c) to the phosphoric acid recovery tank 50 are performed by etching one semiconductor wafer W. Performed every time the process is completed. Then, the phosphoric acid solution (H ₃ PO ₄ ) sequentially stored in the phosphoric acid recovery tank 50 is adjusted to a predetermined temperature by the heater unit 51, and the operation of the pump 52 at a predetermined timing allows the etching solution generation tank 10 to be adjusted. Returned to

According to the above-described substrate processing apparatus, the semiconductor wafer W can be etched one by one by the spin processing unit 30 without requiring a large etching tank as in the batch type. In addition, after the etching processing of the semiconductor wafer W is completed in the spin processing unit 30, the used etching solution LETC is used as the used etching solution LETC for processing one semiconductor wafer W stored in the inner liquid storage cup 33c. Since an appropriate amount of hydrofluoric acid solution is provided with respect to the amount of LETC, the used etching solution LETC and the appropriate amount for processing one semiconductor wafer using the spin processing unit 30 without using a separate large facility are provided. Phosphoric acid (H ₃ PO ₄ ) can be regenerated by efficiently reacting with a hydrofluoric acid solution. In particular, the used etchant LETC originally adjusted to a high temperature (for example, about 160 ° C.) is in a high temperature state even in the inner liquid reservoir cup 33c, so that the hydrofluoric acid solution is given in the form of a mist or vapor, The reactivity of the used etching solution LETC and hydrofluoric acid solution is increased. Then, the fluoride component (for example, H ₂ SiF ₆ ) and the ammonia component (NH ₃ ) after the reaction are immediately diffused by the high temperature environment in the inner liquid reservoir cup 33c in which the used etching solution LETC in a high temperature state is stored. The phosphoric acid can be regenerated more efficiently.

  In the substrate processing apparatus according to the first embodiment described above (see FIGS. 2 to 4), the amount of processed semiconductor wafer W stored in the inner liquid storage cup 33c of the spin processing unit 30 is processed. Although an appropriate amount of hydrofluoric acid solution was given to the used etching solution LETC with respect to the amount of the used etching solution LETC, the present invention is not limited to this. For example, in the process in which two or more predetermined number of semiconductor wafers W are sequentially etched one by one in the spin processing unit 30, the predetermined number of semiconductor wafers are added to the used etching liquid LETC stored in the inner liquid storage cup 33c. An appropriate amount of hydrofluoric acid solution can be provided with respect to the amount of the used etching solution LETC required for the etching process of W. The predetermined number is the total amount of the used etching solution LETC corresponding to the etching amount of the predetermined number of semiconductor wafers W and an appropriate amount of the hydrofluoric acid solution LHF with respect to the amount of the used etching solution LETC. It is determined within a range not exceeding the capacity of the liquid storage cup 33c.

  As described above, when an appropriate amount of hydrofluoric acid solution is mixed with the amount of the used etching solution LETC into the used etching solution LETC obtained by processing the predetermined number of semiconductor wafers W one by one, Until the etching process is completed, the used etching liquid LETC is sequentially stored in the inner liquid storage cup 33c of the spin processing unit 30. For this reason, it is preferable to provide a heater in the inner liquid reservoir cup 33c from the viewpoint of preventing the temperature of the used etching liquid LETC in the inner liquid reservoir cup 33c from decreasing before the hydrofluoric acid solution is added.

In the substrate processing apparatus described above, for example, as shown in FIG. 5, the phosphoric acid solution (H ₃ PO ₄ ) can be regenerated in the spin processing unit 30 (variation of the first embodiment).

In the spin processing unit 30, an appropriate amount of hydrofluoric acid solution with respect to the amount of used etching solution for processing one semiconductor wafer W in the inner liquid storage cup 33 c with the separator 33 b adjusted to the raised position. LHF (HF) is stored in advance. In this state, in the spin processing unit 30, the etching liquid adjusted to a high temperature (for example, about 160 ° C.) supplied from the etching liquid storage tank 20 to the semiconductor wafer W rotated by the substrate spinning mechanism 32 is ejected from the etching liquid. The semiconductor wafer W is etched by being applied from the nozzle 34. In this process, the used etching liquid that scatters from the surface of the rotating semiconductor wafer W enters the inner liquid storage cup 33c in which the hydrofluoric acid solution LHF (HF) has already been stored, and the used etching liquid in the inner liquid storage cup 33c. LETC and hydrofluoric acid solution LHF mix and react in the same manner as described above to regenerate phosphoric acid (H ₃ PO ₄ ).

Thus, a small amount of used etching solution (used etching solution for processing one substrate) and a small amount of hydrofluoric acid react in the inner liquid reservoir cup 33c of the spin processing unit 30. Therefore, without using a separate large facility, the spent etching solution obtained by processing one semiconductor wafer using the spin processing unit 30 and the appropriate amount of the hydrofluoric acid solution LHF are efficiently reacted to form phosphoric acid ( H ₃ PO ₄ ) can be played. In particular, since a high temperature used etching solution is given to the hydrofluoric acid solution LHF stored in the inner liquid storage cup 33c, the reactivity of the used etching solution LETC and the hydrofluoric acid solution is high, and the high temperature used Due to the high temperature environment created by the jetting of the etching solution LETC, the fluoride component and the ammonia component are easily diffused immediately, and phosphoric acid can be efficiently regenerated.

  In the substrate processing apparatus according to the above-described modification (see FIG. 5), the amount of used etching liquid LETC corresponding to the amount of processed semiconductor wafer W in the inner liquid reservoir cup 33c of the spin processing unit 30 is as follows. Although an appropriate amount of the hydrofluoric acid solution LHF has been stored in advance, the present invention is not limited to this. For example, an appropriate amount of hydrofluoric acid solution LHF is stored in advance in the inner liquid storage cup 33c of the spin processing unit 30 with respect to the amount of used etching liquid LETC for processing two or more predetermined number of semiconductor wafers W. Each time the semiconductor wafers W are processed one by one until the processing of the predetermined number of semiconductor wafers W is completed, the used etching solution LETC is supplied to the hydrofluoric acid solution LHF stored in the inner liquid storage cup 33c. It can also be. The predetermined number is the total amount of a mixture of an appropriate amount of hydrofluoric acid solution LHF and the used etching solution LETC with respect to the amount of the used etching solution LETC that has processed the predetermined number of semiconductor wafers W. It is determined within a range not exceeding the capacity of 33c.

  The main part of the substrate processing apparatus according to the second embodiment of the present invention is configured as shown in FIG. In this substrate processing apparatus, phosphoric acid is not regenerated in the spin processing unit 30 but phosphoric acid is regenerated outside the spin processing unit 30.

  In FIG. 6, a regeneration processing tank 60 is provided at the subsequent stage of the spin processing unit 30. The regeneration processing tank 60 is provided with a used etching solution ejection nozzle 63 (used etching supply mechanism). A path extending from the inner liquid reservoir cup 33c of the spin processing unit 30 is connected to the used etching liquid ejection nozzle 63, and an opening / closing valve 37a and a pump 38 are provided in the path. Further, the regeneration treatment tank 60 and the phosphoric acid recovery tank 50 (see FIG. 1) are connected by a path, and an on-off valve 61 and a pump 62 are provided in the path. This substrate processing apparatus has a hydrofluoric acid supply unit 42 (hydrofluoric acid supply mechanism) as in the above-described example (see FIG. 1), and the hydrofluoric acid solution (HF) is supplied from the hydrofluoric acid supply unit 42. It is supplied to the regeneration processing tank 60 instead of the spin processing unit 30.

  Since the hydrofluoric acid solution (HF) is supplied from the hydrofluoric acid supply unit 42 to the regeneration processing tank 60, the spin processing unit 30 is provided with a hydrofluoric acid ejection nozzle 36 as in the above-described example (see FIG. 1). It has not been done. In addition, the substrate processing apparatus is similar to the example shown in FIG. 1 in that a mechanism for generating an etching solution (including an etching solution generation tank 10, a phosphoric acid supply unit 12, a water supply unit 13, and a silica supply unit 14), etching is performed. A mechanism (including the etchant storage tank 20) for storing the liquid and sending it to the spin processing unit 30, and a mechanism (including the phosphoric acid recovery tank 50) for storing the regenerated phosphoric acid solution and returning it to the etchant generation tank 10 ing.

In the substrate processing apparatus according to the second embodiment of the present invention described above, the amount of the hydrofluoric acid solution LHF (HF) relative to the amount of the etching solution for processing one semiconductor wafer W is, for example, the semiconductor wafer W When the nitride film (Si ₃ N ₄ ) formed on the substrate is processed, the amount (appropriate amount) is such that the equivalent of fluorine (F) is about 6 times the concentration of the Si component dissolved in the etching solution. Thus, such an amount (appropriate amount) of hydrofluoric acid solution LHF (HF) is stored in the regeneration treatment tank 60 in advance. In this state, when the etching process of the semiconductor wafer W is completed in the spin processing unit 30, the on-off valve 37 a is switched to the open state, and the pump 38 operates to a high temperature state (for example, 160 ° C.) accumulated in the inner liquid reservoir cup 33 c. The used etching solution LETC is supplied to the regeneration treatment tank 60. In the regeneration processing tank 60, the used etching solution LETC supplied from the spin processing unit 30 is ejected from the used etching solution ejection nozzle 63. The used etching solution in the high temperature state is applied to the hydrofluoric acid solution LHF stored in the regeneration treatment tank 60 in the form of a mist or a part or all of the vaporized state due to the high temperature. In the regeneration treatment tank 60, the used etching solution LETC and the hydrofluoric acid solution LHF are mixed and reacted under a predetermined high temperature environment, and the fluoride component and the ammonia component are diffused to phosphoric acid (H ₃ PO ₄ ) Is played.

  In addition, it is easy to mix the used etching solution LETC and the hydrofluoric acid solution LHF that an appropriate amount of the hydrofluoric acid solution (HF) can be stored in the regeneration treatment tank 60 in a state where the surface area is as large as possible and as shallow as possible. This is preferable.

The on-off valve 61 is opened at a timing when phosphoric acid is expected to be regenerated by mixing the used etching solution LETC and the hydrofluoric acid solution LHF in the regeneration treatment tank 60, and the phosphoric acid solution (H ₃ PO ₄ ) is supplied to the phosphoric acid recovery tank 50 (see FIG. 1) by the operation of the pump 62. Then, in the same manner as described above, the phosphoric acid recovery tank 50 is returned to the etching solution generation tank 10. The opening timing of the on-off valve 61 is determined in advance by experiments or the like.

  According to such a substrate processing apparatus, as in the first embodiment (see FIGS. 1 to 4), a large etching tank as in the batch type is not required, and the spin processing unit 30 performs semiconductor one by one. Etching of the wafer W can be performed. Further, the used etching solution LETC is supplied to the regeneration processing tank 60 in which the hydrofluoric acid solution LHF has been stored in advance, in the amount of processing of one semiconductor wafer W stored in the inner liquid storage cup 33c of the spin processing unit 30. In the regeneration treatment tank 60, the used etching solution LETC and the hydrofluoric acid solution LHF react to regenerate phosphoric acid, so that the used etching solution LETC for processing one semiconductor wafer W and the same are used. On the other hand, the phosphoric acid is regenerated by efficiently reacting the used etching solution LETC and the hydrofluoric acid solution LHF with the use of the regeneration treatment tank 60 having a size capable of storing an appropriate amount of the hydrofluoric acid solution LHF. be able to. In particular, since the high-temperature used etching solution LETC is given in the form of a mist or vapor to the hydrofluoric acid solution LHF stored in the regeneration treatment tank 60, the reactivity of the used etching solution LETC and the hydrofluoric acid solution LHF is high. The fluoride component and the ammonia component are easily easily diffused by the high temperature environment created by the ejection of the high and high temperature used etchant LETC, and the phosphoric acid can be efficiently regenerated.

  In the substrate processing apparatus according to the second embodiment (see FIG. 6) described above, the used etching for processing one semiconductor wafer W stored in the inner liquid storage cup 33c of the spin processing unit 30 is processed. The liquid LETC is given in the form of a mist or vapor to the hydrofluoric acid solution LHF in an appropriate amount with respect to the used etching liquid LETC stored in the regeneration treatment tank 60, but the present invention is not limited to this. For example, an appropriate amount of hydrofluoric acid solution is stored in the regeneration processing tank 60 in advance for the amount of the used etching solution LETC for the etching processing of two or more predetermined number of semiconductor wafers W, and the spin processing unit 30 performs the above process. The hydrofluoric acid stored in the regeneration processing tank 60 in the form of a mist or vapor of the used etching solution LETC stored in the inner liquid storage cup 33c in the process of sequentially etching a predetermined number of semiconductor wafers W one by one. It can also be given to the solution. The predetermined number is determined in a range in which the amount of the used etching solution LETC for the etching processing of the predetermined number of semiconductor wafers W does not exceed the capacity of the inner liquid storage cup 33c.

  Also in this case, it is preferable to provide a heater in the inner liquid reservoir cup 33c from the viewpoint of preventing a temperature drop of the used etching liquid LETC stored in the inner liquid reservoir cup 33c in advance.

  In the substrate processing apparatus according to the second embodiment described above, the hydrofluoric acid solution LHF (HF) is stored in advance in the regeneration processing tank 60 and is stored in the inner liquid storage cup 33c of the spin processing unit 30. Although the used etching solution LETC is sprayed into the regeneration treatment tank 60 in the form of mist or vapor, the present invention is not limited to this. For example, the used etching solution LETC stored in the inner liquid storage cup 33c of the spin processing unit 30 is supplied to the regeneration processing tank 60 and stored in advance, and in this state, the hydrofluoric acid solution LHF is made into a mist or vapor. Then, it may be ejected into the regeneration treatment tank 60. Also in this case, the used etching solution LETC for processing one semiconductor wafer can be stored in the regeneration processing tank 60 with a surface area as wide as possible and as shallow as possible. The hydrofluoric acid solution LHF is preferable in that it can be easily mixed.

  The main part of the substrate processing apparatus according to the third embodiment of the present invention is configured as shown in FIG. In this substrate processing apparatus, phosphoric acid is not regenerated in the spin processing unit 30 but phosphoric acid is regenerated in a regeneration treatment tank 60 provided outside the spin processing unit 30. The substrate processing apparatus provided with the main part shown in FIG. 7 is the substrate processing apparatus according to the second embodiment in that a hydrofluoric acid jet nozzle 64 (hydrofluoric acid supply mechanism) is provided in the regeneration processing tank 60. (See FIG. 6).

In such a substrate processing apparatus, when the etching process of the semiconductor wafer W is completed in the spin processing unit 30, the on-off valve 37a is switched to the open state, and the used etching accumulated in the inner liquid reservoir cup 33c by the operation of the pump 38. The liquid LETC is supplied to the regeneration treatment tank 60. At the same time, a hydrofluoric acid solution (HF) is supplied from the hydrofluoric acid supply unit 42 to the regeneration treatment tank 60. In the regeneration treatment tank 60, the used etching solution LETC in a high temperature state (for example, about 160 ° C.) supplied from the spin processing unit 30 is partially or partially formed from the used etching solution ejection nozzle 63 in the form of a mist. The whole is vaporized and ejected, and at the same time, the hydrofluoric acid solution (HF) supplied from the hydrofluoric acid supply unit 42 is ejected from the hydrofluoric acid nozzle 64 in liquid form, preferably in the form of a mist. Then, a high-temperature mist-like or vapor-like used etching solution LETC and a hydrofluoric acid solution that is vaporized in whole or in part by a high-temperature environment created by the ejection of the high-temperature used etching solution LETC. Under the high temperature environment, they mix and react, and the fluoride and ammonia components are diffused to regenerate phosphoric acid (H ₃ PO ₄ ).

  The particle sizes of the used etching solution LETC and the hydrofluoric acid solution (HF) that are in the form of a mist are preferably as small as possible because they can be easily mixed and can exhibit high reactivity.

  According to such a substrate processing apparatus, as in the first embodiment (see FIGS. 1 to 4) and the second embodiment (see FIG. 6), a large etching tank such as a batch type is required. Instead, the semiconductor wafer W can be etched one by one by the spin processing unit 30. Further, in the regeneration processing tank 60, an amount appropriate for the amount of the used etching solution LETC and the amount of the etching solution corresponding to the amount of processed one semiconductor wafer W stored in the inner liquid storage cup 33c of the spin processing unit 30. Since the phosphoric acid is regenerated by reacting with the hydrofluoric acid solution LHF in the form of a mist or vapor, the used etching is performed using a relatively small regeneration treatment tank 60 as in the second embodiment. Phosphoric acid can be regenerated by efficiently reacting the liquid LETC with the hydrofluoric acid solution LHF. In particular, the mist or vapor used etching solution LETC and hydrofluoric acid solution LHF are mixed in the regeneration treatment tank 60 in a predetermined high temperature environment, so that the reactivity is high, and the fluoride component and the ammonia component depend on the high temperature environment. However, phosphoric acid can be regenerated by reacting efficiently.

  In the substrate processing apparatus according to the third embodiment described above (see FIG. 7), the used etching for processing one semiconductor wafer W stored in the inner liquid storage cup 33c of the spin processing unit 30 is used. The liquid LETC and an appropriate amount of the hydrofluoric acid solution LHF with respect to the amount of the used etching liquid LETC were mixed and reacted in the form of mist or vapor in the regeneration treatment tank 60. The invention is not limited to this. For example, a used etching solution LETC stored in the inner liquid storage cup 33c in a process in which two or more predetermined number of semiconductor wafers W are sequentially etched one by one in the spin processing unit 30, and the used etching solution LETC. An appropriate amount of the hydrofluoric acid solution LHF may be mixed in a mist or vapor in the regeneration treatment tank 60 to react with each other. The predetermined number is determined in a range in which the amount of the used etching solution LETC for the etching processing of the predetermined number of semiconductor wafers W does not exceed the capacity of the inner liquid storage cup 33c.

  Also in this case, it is preferable to provide a heater in the inner liquid reservoir cup 33c from the viewpoint of preventing a temperature drop of the used etching liquid LETC stored in the inner liquid reservoir cup 33c in advance.

  The main part of the substrate processing apparatus according to the fourth embodiment of the present invention is configured as shown in FIG. This substrate processing apparatus is not a single-wafer type that processes semiconductor wafers W one by one, as in each of the above-described substrate processing apparatuses, but is a batch type that processes a plurality of semiconductor wafers W collectively. .

In FIG. 8, the substrate processing apparatus includes a batch processing tank 70 (etching processing unit) and a regeneration processing tank 80. The batch processing tank 70 is an etching liquid generation tank (etching liquid generation in FIG. 1) that mixes phosphoric acid solution (H ₃ PO ₄ ), pure water (H ₂ O), and colloidal silica (SiO ₂ ) to generate an etching liquid. Equivalent to the tank 10). Then, in the batch processing tank 70, an etching solution sufficient for etching a predetermined number of semiconductor wafers W is supplied from the etching solution generation tank and stored. The batch processing tank 70 is provided with a heater unit 71, and the stored etching solution is maintained at a predetermined temperature.

  The substrate processing apparatus further includes a hydrofluoric acid supply unit 84. The regeneration treatment tank 80 is provided with a used etching solution ejection nozzle 81 and a hydrofluoric acid ejection nozzle 82. The used etching solution jet nozzle 81 is connected to the batch processing tank 70 via an on-off valve 72, and the hydrofluoric acid jet nozzle 82 is connected to a hydrofluoric acid supply unit 84. One of the two paths extending from the bottom of the regeneration treatment tank 80 is connected to a phosphoric acid recovery tank (corresponding to the phosphoric acid recovery tank 50 shown in FIG. 1) via an on-off valve 86a, and the other is connected to an on-off valve. It is connected to the waste liquid tank via 86b.

  In such a substrate processing apparatus, an etching process for a predetermined number of semiconductor wafers W is collectively performed in the batch processing tank 70. In the process of repeatedly performing the etching process on the semiconductor wafer W performed in units of a predetermined number, for example, it is newly generated from the etching solution generation tank so that the etching rate of each semiconductor wafer W is maintained within a predetermined range. An etching solution is supplied to the batch processing tank 70 at a predetermined timing. In addition, the used etching solution LETC is supplied from the batch processing tank 70 to the regeneration processing tank 80 by opening the on-off valve 72 at a predetermined timing for a predetermined time.

In the regeneration processing tank 80, the used etching liquid LETC in a high temperature state (for example, about 160 ° C.) supplied from the batch processing tank 70 for a predetermined time at a predetermined timing is sprayed from the used etching liquid ejection nozzle 81, or The hydrofluoric acid solution LHF supplied from the hydrofluoric acid supply unit 84 is in a liquid state, preferably in the form of a mist, from the hydrofluoric acid injection nozzle 82 in synchronism with a part or all of the vaporized jet due to the high temperature And erupts. The mist-like or vapor-like used etching solution LETC and the hydrofluoric acid solution LHF, which is vaporized in whole or in part by the high-temperature environment created by the ejection of the used etching solution LETC in the high temperature state, It reacts by mixing under a high temperature environment, and the fluoride component and ammonia component are diffused to regenerate phosphoric acid (H ₃ PO ₄ ).

  The phosphoric acid solution regenerated in the regeneration treatment tank 80 is supplied to the phosphoric acid collection tank, and is further returned from the phosphoric acid collection tank to the etching solution generation tank.

  According to the above-described substrate processing apparatus, even if a large amount of etching solution is used for batch etching of a predetermined number of semiconductor wafers W in the batch processing tank 70, the used etching liquid LETC and Since the hydrofluoric acid solution LHF mixes and reacts in the form of a mist or vapor, it reacts by accumulating all the amounts of the used etching solution LETC and the hydrofluoric acid solution LHF after the etching process for a plurality of semiconductor wafers W. Without using the equipment to be used, phosphoric acid can be regenerated by efficiently reacting the used etching solution with the hydrofluoric acid solution.

  In the second embodiment (see FIG. 6), the third embodiment (see FIG. 7), and the fourth embodiment (see FIG. 8), the used etching solution jet nozzles 63 and 81 are used. The used etching solution LETC is ejected in the form of a mist or vapor. However, the used etching solution LETC may be ejected in a liquid state without becoming a mist or vapor.

DESCRIPTION OF SYMBOLS 10 Etching liquid production | generation tank 11 Heater unit 12 Phosphoric acid supply part 13 Water supply part 14 Silica supply part 15 Pump 16 Switching valve 17 Concentration detector 20 Etching liquid storage tank 21 Heater unit 22a, 22b On-off valve 23 Pump 24 Flow meter 25 Switching Valve 26 Cooler 30 Spin processing unit 31 Processing chamber 32 Substrate spin mechanism 33 Separate cup mechanism 34 Etching solution ejection nozzle 35 Rinse solution ejection nozzle 36 Hydrofluoric acid ejection nozzle 37a, 37b Open / close valve 38 Pump 41 Rinse fluid supply unit 42 Hydrofluoric acid supply Portion 50 Phosphoric acid recovery tank 51 Heater unit 52 Pump 60 Regeneration treatment tank 61 On-off valve 62 Pump 63 Used etchant ejection nozzle 64 Hydrofluoric acid ejection nozzle 70 Batch treatment tank 71 Heater unit 80 Regeneration treatment tank 81 Use Etched only liquid discharge nozzle 82 hydrofluoric acid jetting nozzle 84 hydrofluoric acid supply unit 86a, 86b off valve

Claims (6)

A substrate processing apparatus for processing a silicon substrate on which a nitride film is formed using an etching solution containing phosphoric acid,
A processing chamber;
A substrate spin mechanism that is provided in the processing chamber and rotates while holding the substrate;
An etchant supply mechanism for supplying the etchant to the surface of the substrate rotated by the substrate spin mechanism;
A liquid reservoir portion that is provided in the processing chamber and stores the used etching liquid obtained after the etching liquid supplied to the surface of the rotating substrate is scattered from the surface of the substrate;
A hydrofluoric acid supply mechanism for supplying a hydrofluoric acid solution to the liquid reservoir;
A phosphoric acid recovery unit for returning phosphoric acid regenerated by mixing the used etching solution and the hydrofluoric acid solution in the liquid reservoir to the etching solution used in the etching solution supply mechanism;
A substrate processing apparatus comprising:   The substrate processing apparatus according to claim 1, wherein the hydrofluoric acid supply mechanism supplies the hydrofluoric acid solution in a state where the used etching solution is stored in the liquid reservoir.   The substrate processing apparatus according to claim 2, wherein the hydrofluoric acid supply mechanism supplies the hydrofluoric acid solution to the liquid reservoir after the processed substrate has exited from the processing chamber.   The etching liquid supply mechanism supplies the etching liquid to the substrate in a state where the hydrofluoric acid solution supplied from the hydrofluoric acid supply mechanism is stored in the liquid reservoir. The substrate processing apparatus as described.   In the processing chamber, an inner liquid reservoir cup is provided around the substrate spin mechanism, and an outer liquid reservoir cup is provided outside the inner liquid reservoir cup. The inner liquid reservoir cup constitutes the liquid reservoir. The substrate processing apparatus according to claim 1, wherein:   6. The phosphoric acid is regenerated by mixing the used etching solution used for processing one substrate with the hydrofluoric acid solution in the liquid reservoir. Substrate processing equipment.

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