Oxide film removal device

Abstract

The present invention provides an oxide film removal apparatus that can uniformly remove the oxide film from a wafer in the circumferential direction and suppress the consumption of etching gas. [Solution] An oxide film removal apparatus comprising an etching chamber, a table on which a wafer having an oxide film on its lower surface is placed, a gas supply unit that supplies etching gas toward the ceiling of the etching chamber, and a gas discharge unit, wherein the etching gas is brought into contact with the oxide film to remove it, the apparatus comprising a rectifier plate that partitions the space between the ceiling and the table in the vertical direction, the rectifier plate having a group of openings through which the etching gas passes, the group of openings consisting of a plurality of openings arranged in a two-dimensional periodic arrangement pattern so as to overlap with the wafer, the rectifier plate having an opening group forming region where the group of openings is formed, and a peripheral region provided around the entire circumference outside the opening group forming region to block the downward flow of the etching gas, wherein the oxide film removal apparatus comprises an etching chamber, a table on which a wafer having an oxide film on its lower surface is placed, a gas supply unit that supplies etching gas toward the ceiling of the etching chamber, and a gas discharge unit, wherein the oxide film removal apparatus comprises an etching plate that partitions the space between the ceiling and the table in the vertical direction, the group of openings consists of a plurality of openings arranged in a two-dimensional periodic arrangement pattern so as to overlap with the wafer, and the rectifier plate has an opening group forming region where the group of openings is formed, and a peripheral region provided around the entire circumference outside the opening group forming region to block the downward flow of the etching gas.

Description

Technical Field

[0001] The present invention relates to an oxide film removing apparatus.

Background Art

[0002] An oxide film removing apparatus is known which has an etching chamber, a table which is provided in the etching chamber and has a circular shape in a top view for placing a circular wafer having an oxide film on its lower surface on its upper surface, a gas supply unit for supplying an etching gas toward the ceiling of the etching chamber, and a gas discharge unit for discharging the etching gas flowing down from the ceiling in the etching chamber, and removes the oxide film by bringing the etching gas into contact with the oxide film of the wafer placed on the upper surface of the table (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the oxide film removing apparatus as described above, since the flow rate of the etching gas when contacting the oxide film is non-uniform in the circumferential direction, the etching reaction becomes supply rate-limiting from reaction rate-limiting in the portion where the flow rate is low, and there is a problem that the removal amount of the oxide film becomes non-uniform in the circumferential direction depending on the flow rate. By increasing the flow rate of the supplied etching gas and setting the flow rate to be reaction rate-limiting over the entire circumference, the removal amount of the oxide film can be made uniform, but this increases the consumption amount of the etching gas.

[0005] An object of the present invention is to provide an oxide film removing apparatus capable of making the removal amount of the oxide film of a wafer uniform in the circumferential direction and suppressing the consumption amount of the etching gas.

Means for Solving the Problems

[0006] One embodiment of the present invention is as follows:

[0007] [1] An etching chamber formed inside the housing, A circular table, in its top view, is provided in the etching chamber, on which a circular wafer having an oxide film on its lower surface is placed. A gas supply unit is provided above the upper surface of the table and supplies etching gas toward the ceiling of the etching chamber, It has a gas discharge section provided below the upper surface of the table, which discharges the etching gas flowing down from the ceiling in the etching chamber, An oxide film removal apparatus that removes the oxide film by bringing the etching gas into contact with the oxide film on the wafer placed on the upper surface of the table, It has a rectifier plate that extends horizontally below the gas supply section and divides the space between the ceiling of the etching chamber and the upper surface of the table in the vertical direction, The rectifier plate has a group of openings that allow the etching gas flowing down from the ceiling in the etching chamber to pass downwards, The aforementioned group of openings consists of a plurality of openings arranged in a two-dimensional periodic arrangement pattern so as to overlap with the wafer placed on the upper surface of the table when viewed from above. The rectifier plate has an opening group forming region in which the opening group is formed, and a peripheral region that is provided around the entire circumference outside the opening group forming region in a top view, and prevents the downward flow of the etching gas flowing down from the ceiling in the etching chamber, in an oxide film removal apparatus.

[0008] [2] The oxide film removal apparatus according to [1], wherein the aperture group forming region is circular in the top view.

[0009] [3] The oxide film removal apparatus according to [1] or [2], wherein in the top view, the center of the aperture group formation region is located in the central part of the wafer placed on the top surface of the table.

[0010] [4] The oxide film removal apparatus according to any one of [1] to [3], wherein, in the top view, the aperture group formation region overlaps the entire wafer placed on the top surface of the table.

[0011] [5] It has a second rectifier plate that extends horizontally below the gas supply section and divides the space between the ceiling and the rectifier plate in the etching chamber in the vertical direction, The second rectifier plate has a group of openings that allow the etching gas flowing down from the ceiling in the etching chamber to pass downwards, The oxide film removal apparatus according to any one of [1] to [4], wherein the group of openings of the second rectifier plate comprises a plurality of openings arranged in a two-dimensional periodic arrangement pattern across the entire surface of the second rectifier plate.

[0012] [6] The oxide film removal apparatus according to [5], wherein the total opening area of ​​the opening group of the second rectifier plate is greater than the total opening area of ​​the opening group of the rectifier plate.

[0013] [7] The table has a third rectifier plate that extends horizontally below the upper surface and above the gas discharge section, and vertically divides the space between the floor of the etching chamber and the rectifier plate. The third rectifier plate has a group of openings that allow the etching gas flowing down from the ceiling in the etching chamber to pass downwards, The oxide film removal apparatus according to [1] to [6], wherein the group of openings of the third rectifier plate comprises a plurality of openings arranged in a two-dimensional periodic arrangement pattern across the entire surface of the third rectifier plate.

[0014] [8] The oxide film removal apparatus according to [7], wherein the group of openings of the third rectifier plate has an opening size distribution in which the size of the openings increases as it approaches the center of the table when viewed from above.

[0015] [9] A wafer manufacturing method having an oxide film removing step by the oxide film removing apparatus described in [1] to [8].

Effect of the Invention

[0016] According to the present invention, it is possible to provide an oxide film removing apparatus capable of making the removal amount of the oxide film on the wafer uniform in the circumferential direction and suppressing the consumption amount of the etching gas.

Brief Description of the Drawings

[0017] [Figure 1] It is a cross-sectional view showing an oxide film removing apparatus in an embodiment of the present invention. [Figure 2] It is a top view of the rectifying plate shown in FIG. 1. [Figure 3] It is a top view of the second rectifying plate shown in FIG. 1. [Figure 4] It is a top view of the third rectifying plate shown in FIG. 1. [Figure 5] It is a graph showing the measurement results in the examples.

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be illustrated and described with reference to the drawings.

[0019] As shown in Figure 1, in one embodiment of the present invention, the oxide film removal apparatus 1 includes an etching chamber 2a that is not circular in top view (rectangular in top view in this embodiment) formed inside a housing 2, a table 4 provided inside the etching chamber 2a on which a circular semiconductor wafer 3 such as silicon, having an oxide film 3a on its lower surface, is placed concentrically on its upper surface and forms a circle with a central axis O located in the center of the etching chamber 2a in top view, a gas supply pipe 5 provided above the upper surface of the table 4 and extending upward from the floor of the etching chamber 2a with an opening at its upper end to supply an etching gas such as hydrofluoric acid gas toward the ceiling of the etching chamber 2a, and a gas discharge pipe 6 provided below the upper surface of the table 4 and extending upward from the floor of the etching chamber 2a with an opening at its upper end to discharge an etching gas flowing down from the ceiling in the etching chamber 2a, and the oxide film 3a is removed (etched) by bringing the etching gas into contact with the oxide film 3a of the wafer 3 placed on the upper surface of the table 4.

[0020] In this embodiment, the vertical direction is referred to as the up-and-down direction, which is the direction along the central axis O of the table 4, the direction perpendicular to the central axis O is referred to as the radial direction, and the direction that circles the central axis O is referred to as the circumferential direction.

[0021] As shown in Figures 1 and 2, the oxide film removal apparatus 1 has a flow straightening plate 7 that extends horizontally below the gas supply unit 5a and divides the space between the ceiling of the etching chamber 2a and the upper surface of the table 4 in the vertical direction. The flow straightening plate 7 has a group of openings 7a that allow etching gas flowing down from the ceiling in the etching chamber 2a to pass downwards. The group of openings 7a consists of a plurality of openings 7a1 arranged in a two-dimensional periodic arrangement pattern so as to overlap with the wafer 3 placed on the upper surface of the table 4 when viewed from above. The flow straightening plate 7 has an opening group forming region 7b where the group of openings 7a is formed, and a peripheral region 7c that is provided around the entire circumference outside the opening group forming region 7b when viewed from above and prevents the downward flow of etching gas flowing down from the ceiling in the etching chamber 2a.

[0022] According to the above configuration, in the aperture group formation region 7b of the rectifier plate 7, the etching gas flow velocity is made uniform by passing through an aperture group 7a in which multiple openings 7a1 are arranged periodically. In addition, in the peripheral region 7c of the rectifier plate 7, the downward flow of the etching gas is blocked, so the flow velocity of the etching gas passing through the aperture group formation region 7b is increased. Furthermore, since the aperture group formation region 7b is located in a position that overlaps with the wafer 3 when viewed from above, the etching gas can be supplied to the oxide film 3a located on the outer edge of the wafer 3 at a flow velocity that is uniform in the circumferential direction and increased, so that the etching reaction can be maintained as the reaction-limiting step, the amount of oxide film 3a removed can be made uniform in the circumferential direction, and the consumption of etching gas can be suppressed.

[0023] As in this embodiment, when the wafer 3 is circular in top view and the etching chamber 2a is not circular in top view, the radial width of the flow path between the outer edge of the wafer 3 and the outer wall surface of the etching chamber 2a becomes non-uniform in the circumferential direction. For example, when the top view shape of the etching chamber 2a is rectangular as in this embodiment, the radial width of the flow path is larger at the corners of the etching chamber 2a in top view compared to other parts. Therefore, if the rectifier plate 7 is provided with an aperture group formation region 7b over its entire surface without a peripheral region 7c, the flow velocity at the outer edge of the wafer 3 tends to become non-uniform in the circumferential direction. With the above configuration, which provides a peripheral region 7c on the rectifier plate 7, such non-uniformity can be suppressed.

[0024] The diameter of wafer 3 is not particularly limited, for example, 300 mm. The outer diameter (diameter) of the aperture cluster formation region 7b is preferably 2 / 3 or more and 4 / 3 or less of the diameter of wafer 3. The aperture cluster formation region 7b is preferably circular when viewed from above, as in this embodiment.

[0025] In a top view, the center of the aperture group formation region 7b is preferably located in the center of the wafer 3 placed on the upper surface of the table 4, as in this embodiment. More preferably, in a top view, the distance between the center of the aperture group formation region 7b and the center of the wafer 3 placed on the upper surface of the table 4 is 1 / 6 or less of the diameter of the wafer 3. In a top view, the aperture group formation region 7b is preferably overlapping the entire wafer 3 placed on the upper surface of the table 4, as in this embodiment. In a top view, the aperture group 7a of the rectifier plate 7 is preferably having an aperture size distribution such that the size of the apertures 7a1 is constant across the entire aperture group formation region 7b, as in this embodiment.

[0026] The vertical distance between the rectifier plate 7 and the wafer 3 is preferably 15 mm or more. With the above configuration, the etching gas accelerated when passing through the opening 7a1 can be decelerated between the rectifier plate 7 and the wafer 3 to equalize the gas flow velocity. In addition, it is possible to easily load and unload the wafer 3 into and out of the etching chamber 2a.

[0027] As shown in Figures 1 and 3, the oxide film removal apparatus 1 has a second rectifier plate 8 that extends horizontally below the gas supply unit 5a and divides the space between the ceiling of the etching chamber 2a and the rectifier plate 7 in the vertical direction. The second rectifier plate 8 has a group of openings 8a that allow etching gas flowing down from the ceiling in the etching chamber 2a to pass downwards, and the group of openings 8a of the second rectifier plate 8 consists of a plurality of openings 8a1 arranged in a two-dimensional periodic arrangement pattern across the entire surface of the second rectifier plate 8. With the above configuration, the etching gas can be rectified by the second rectifier plate 8 before it passes through the rectifier plate 7, so that the etching gas can be supplied to the wafer 3 more uniformly. Preferably, the group of openings 8a of the second rectifier plate 8 has an opening size distribution such that the size of the openings 8a1 is constant across the entire surface of the second rectifier plate 8 when viewed from above.

[0028] The total opening area of ​​the opening group 8a of the second rectifier plate 8 is preferably larger than the total opening area of ​​the opening group 7a of the rectifier plate 7. With the above configuration, the rectifying effect of the etching gas by the rectifier plate 7 can be easily obtained.

[0029] The vertical distance between the rectifier plate 7 and the second rectifier plate 8 is preferably 10 mm or more and 40 mm or less. With the above configuration, by setting the distance to 10 mm or more, the etching gas accelerated when passing through the opening 8a1 of the second rectifier plate 8 can be decelerated between the second rectifier plate 8 and the rectifier plate 7 to equalize the gas flow velocity, making it easier for the rectifier plate 7 to rectify the etching gas, and by setting the distance to 40 mm or less, the size of the oxide film removal device 1 can be suppressed.

[0030] As shown in Figures 1 and 4, the oxide film removal apparatus 1 has a third rectifier plate 9 that extends horizontally below the upper surface of the table 4 and above the gas discharge section 6a, and vertically divides the space between the floor of the etching chamber 2a and the rectifier plate 7. The third rectifier plate 9 has a group of openings 9a that allow etching gas flowing down from the ceiling in the etching chamber 2a to pass downwards, and the group of openings 9a of the third rectifier plate 9 consists of a plurality of openings 9a1 arranged in a two-dimensional periodic arrangement pattern across the entire surface of the third rectifier plate 9. The third rectifier plate 9 has a central through-hole 9b that penetrates the table 4 in its center.

[0031] The opening group 9a of the third rectifier plate 9 preferably has an opening size distribution in which the size of the opening 9a1 increases as it approaches the center of the table 4 when viewed from above, as in this embodiment. With the above configuration, the flow of etching gas that passes near the outer edge of the wafer 3 and near the outer edge of the table 4 and flows below the third rectifier plate 9 increases, so that the flow velocity at the outer edge of the wafer 3 can be made more uniform in the circumferential direction.

[0032] In each of the rectifier plate 7, the second rectifier plate 8, and the third rectifier plate 9, it is preferable that the openings 7a1, 8a1, and 9a1 consist of a single circular opening in top view, as in this embodiment. However, the openings 7a1, 8a1, and 9a1 are not limited to this configuration; they may also consist of a single non-circular opening in top view, or a configuration consisting of multiple openings.

[0033] In each of the rectifier plate 7, the second rectifier plate 8, and the third rectifier plate 9, it is preferable that the multiple openings 7a1, 8a1, and 9a1 constituting the opening groups 7a, 8a, and 9a are arranged linearly at a first predetermined pitch in the first horizontal direction and linearly at a second pitch in the second horizontal direction, with the first and second horizontal directions being different and the first and second pitches being the same, as in this embodiment. Furthermore, it is preferable that the first and second horizontal directions are perpendicular, as in this embodiment. However, a configuration in which the first and second horizontal directions intersect at an angle other than perpendicular is also possible.

[0034] The rectifier plate 7, the second rectifier plate 8, and the third rectifier plate 9 each have through holes 7d, 8b, and 9c through which the gas supply pipe 5 passes.

[0035] The oxide film removal apparatus 1 preferably has an openable and closable shutter (not shown) for loading and unloading wafers 3 into and out of the etching chamber 2a, located on the peripheral wall of the etching chamber 2a below the rectifier plate 7 and above the third rectifier plate 9.

[0036] In one embodiment of the present invention, the wafer 3 manufacturing method includes an oxide film removal step using an oxide film removal apparatus 1. The oxide film removal step is performed by placing the wafer 3 on the upper surface of the table 4, supplying etching gas from the gas supply unit 5a, passing the second rectifier plate 8, the rectifier plate 7, and the third rectifier plate 9 in that order, and discharging the gas to the gas discharge unit 6a. The wafer 3 manufacturing method may also be configured to include a film formation step in which an epitaxial layer is formed on the upper surface of the wafer 3 from which the oxide film 3a has been removed by the oxide film removal step.

[0037] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and the embodiments described above can be modified in various ways without departing from the spirit of the present invention. [Examples]

[0038] The gas flow velocity at the outer edge of the wafer was measured in both the oxide film removal apparatus according to this embodiment (as an example) and the oxide film removal apparatus as a comparative example. The comparative example differed from the embodiment in that the group of openings in the rectifier plate consisted of multiple openings arranged in a two-dimensional periodic pattern across the entire surface of the rectifier plate, and the group of openings in the third rectifier plate had an opening size distribution in which the size of the openings was constant when viewed from above. Otherwise, it was the same as the embodiment. In both the embodiment and the comparative example, the gas flow rate of the etching gas was adjusted so that the average gas flow velocity averaged in the circumferential direction at the outer edge of the wafer was the same. The measurement results for both are shown in Figure 5. In Figure 5, the gas flow velocity is shown normalized with the average gas flow velocity set to 1. From the results shown in Figure 5, the embodiment was able to reduce the variation in circumferential gas flow velocity by 51% and reduce the gas flow rate by 78% compared to the comparative example. [Explanation of symbols]

[0039] 1. Oxide film removal device 2 cabinets 2a Etching Room 3 wafers 3a Oxide film 4 tables 5. Gas supply pipe 5a Gas Supply Department 6. Gas discharge pipe 6a Gas discharge section 7 Rectifier plate 7a aperture group 7a1 opening 7b Aperture group formation area 7c Peripheral area 7d through hole 8 Second rectifier plate 8a aperture group 8a1 opening 8b Through hole 9 Third rectifier plate 9a aperture group 9a1 opening 9b Center through hole 9c through hole O center axis

Claims

1. An etching chamber formed inside the housing, A circular table, in its top view, is provided in the etching chamber, on which a circular wafer having an oxide film on its lower surface is placed. A gas supply unit is provided above the upper surface of the table and supplies etching gas toward the ceiling of the etching chamber, It has a gas discharge section provided below the upper surface of the table, which discharges the etching gas flowing down from the ceiling in the etching chamber, An oxide film removal apparatus that removes the oxide film by bringing the etching gas into contact with the oxide film on the wafer placed on the upper surface of the table, It has a rectifier plate that extends horizontally below the gas supply section and divides the space between the ceiling of the etching chamber and the upper surface of the table in the vertical direction, The rectifier plate has a group of openings that allow the etching gas flowing down from the ceiling in the etching chamber to pass downwards, The group of openings consists of a plurality of openings arranged in a two-dimensional periodic arrangement pattern so as to overlap with the wafer placed on the upper surface of the table when viewed from above. The rectifier plate has an opening group forming region in which the opening group is formed, and a peripheral region that is provided around the entire circumference outside the opening group forming region in a top view, and prevents the downward flow of the etching gas flowing down from the ceiling in the etching chamber, in an oxide film removal apparatus.

2. The oxide film removal apparatus according to claim 1, wherein the aperture group forming region is circular in the top view.

3. The oxide film removal apparatus according to claim 1, wherein, in the top view, the center of the aperture group formation region is located in the central part of the wafer placed on the top surface of the table.

4. The oxide film removal apparatus according to claim 1, wherein, in the top view, the aperture group formation region overlaps the entire wafer placed on the top surface of the table.

5. It has a second rectifier plate that extends horizontally below the gas supply section and divides the space between the ceiling and the rectifier plate in the etching chamber in the vertical direction, The second rectifier plate has a group of openings that allow the etching gas flowing down from the ceiling in the etching chamber to pass downwards, The oxide film removal apparatus according to claim 1, wherein the group of openings of the second rectifier plate consists of a plurality of openings arranged in a two-dimensional periodic arrangement pattern over the entire surface of the second rectifier plate.

6. The oxide film removal apparatus according to claim 5, wherein the total opening area of ​​the opening group of the second rectifier plate is greater than the total opening area of ​​the opening group of the rectifier plate.

7. The table has a third rectifier plate that extends horizontally below the upper surface and above the gas discharge section, and vertically divides the space between the floor of the etching chamber and the rectifier plate. The third rectifier plate has a group of openings that allow the etching gas flowing down from the ceiling in the etching chamber to pass downwards, The oxide film removal apparatus according to claim 1, wherein the group of openings of the third rectifier plate consists of a plurality of openings arranged in a two-dimensional periodic arrangement pattern over the entire surface of the third rectifier plate.

8. The oxide film removal apparatus according to claim 7, wherein the group of openings of the third rectifier plate has an opening size distribution in which the size of the openings increases as it approaches the center of the table when viewed from above.

9. A wafer manufacturing method comprising an oxide film removal step using the oxide film removal apparatus described in claim 1.

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