JP7607367B1 - Shallow Etch Process Chamber - Google Patents

Abstract

A shallow etch process chamber is provided.
[Solution] The shallow etching process chamber includes a susceptor disposed inside a chamber space 11; a lift ring 13 formed on both sides of the susceptor; and a moving means for raising and lowering the lift ring 13; and a wafer (W) can be freely raised and lowered above the susceptor by raising and lowering the lift ring 13.
[Selected Figure] Figure 1

Description

The present invention relates to a shallow etching process chamber, and more specifically, to a shallow etching process chamber that is capable of adjusting the etching process space during the etching process.

As semiconductor manufacturing processes become finer and more three-dimensional, there is a demand for technologies that can remove thin oxide layers or thin layers with very high aspect ratios in some etching processes. In addition, to minimize the loading effect, which is the difference in the amount of etching between relatively wide and narrow patterns, technologies are being developed that gradually etch repeatedly at the atomic layer level without the loading effect. Technologies such as ALE (Atomic Layer Etching), ALR (Atomic Layer Removal) and dry cleaning are in the process of being developed as atomic layer etching technologies with such high aspect ratios. The common feature of such shallow etching processes is that they include an adsorption step by a self-limited modification reaction at a low temperature of 80° C. or less, and a removal step to remove the modified atomic layer-level thin film at a high temperature of 120° C. or more. Known equipment for shallow etching performs both the adsorption step and the removal step as a thermal process, and such equipment has a drawback in that it requires a long process time and has a limited productivity. In addition, equipment has been developed that performs the adsorption step using plasma energy and the removal step using thermal energy, and various attempts have been made to change the low temperature and high temperature stepwise. In relation to ALE, Patent Document 1 discloses a method and apparatus for processing a semiconductor substrate. Patent Document 2 discloses a method for manufacturing a microelectronic workpiece including the formation of a patterned structure on the microelectronic workpiece. However, the prior art does not disclose ALE or dry cleaning techniques that can simultaneously satisfy high efficiency and productivity.

The present invention is intended to solve the problems of the prior art and has the following objectives:

Republic of Korea Patent Publication No. 10-2017-0124087 (Lam Research Corporation, published 2017.11.09) Etching a substrate using ALE and selective deposition Republic of Korea Patent Publication No. 10-2020-0116273 (Tokyo Electron Limited, published on October 7, 2020) Atomic layer etching of tungsten or other metal layers

The object of the present invention is to provide a shallow etching process chamber that can perform a low-temperature adsorption step using plasma energy while simultaneously achieving high efficiency and productivity.

According to a suitable embodiment of the present invention, the shallow etch process chamber includes a susceptor disposed inside the chamber space; lift rings formed on both sides of the susceptor; and a moving means for raising and lowering the lift ring, so that the wafer can be freely raised and lowered above the susceptor by raising and lowering the lift ring.

According to another suitable embodiment of the present invention, the chamber further includes an internal showerhead and an external showerhead disposed at the top of the chamber space 11, and a showerhead heater is disposed in the internal showerhead.

According to another suitable embodiment of the present invention, the showerhead further includes a baffle disposed between the internal showerhead and the external showerhead.

According to yet another suitable embodiment of the present invention, the rising lift ring is brought into contact with the baffle.

According to yet another suitable embodiment of the present invention, the elevated lift ring forms a process space between the internal showerhead and the wafer.

According to yet another suitable embodiment of the present invention, the device further includes a ring heater disposed inside the lift ring.

According to yet another suitable embodiment of the present invention, the moving means includes a linear gear and a lift shaft movable along the linear gear.

According to yet another suitable embodiment of the present invention, the apparatus further includes a movable gas wall that can be raised and lowered to surround the internal showerhead and an upper portion of the internal showerhead.

According to yet another suitable embodiment of the present invention, a flow path is formed in the baffle.

According to yet another suitable embodiment of the present invention, the lift ring contacts the bottom surface of the baffle, contacts a portion of the bottom surface of the baffle, or contacts the bottom surface and the inner surface of the baffle.

The shallow etching process chamber according to the present invention efficiently advances the adsorption step by rapidly changing the wafer temperature while performing a low-temperature adsorption step and a high-temperature removal step relative to the wafer temperature using plasma energy in one chamber. This improves the process efficiency of removing thin films with high aspect ratios while improving productivity. The shallow etching process chamber according to the present invention is applicable to various fine processes including the ALE process, but the present invention is not limited thereto.

1 illustrates an embodiment of a shallow etch process chamber in accordance with the present invention. 1 is a diagram showing an embodiment of an operating structure of a process chamber according to the present invention; 4 is a diagram illustrating an embodiment of a relative positional relationship between a baffle and a lift ring in a process chamber according to the present invention. 1 is a diagram illustrating another embodiment of a shallow etch process chamber according to the present invention. 1 is a diagram illustrating an embodiment of a process of performing an ALE process in an etching process chamber according to the present invention.

The present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings. However, the embodiments are for a clear understanding of the present invention, and the present invention is not limited thereto. In the following description, components having the same reference numerals in different drawings have similar functions, and therefore will not be described repeatedly unless necessary for understanding the invention. Known components will be described briefly or omitted, but will not be understood as being excluded from the embodiments of the present invention.

Figure 1 illustrates an embodiment of a shallow etch process chamber according to the present invention.

Referring to FIG. 1, the shallow etching process chamber includes a susceptor disposed inside a chamber space 11; lift rings 13 formed on both sides of the susceptor; and a moving means for raising and lowering the lift ring 13; and the wafer (W) can be freely raised and lowered above the susceptor by raising and lowering the lift ring 13.

The chamber space 11 is separated from the outside by a bottom surface and a surrounding wall, and a cover (C) may be attached to the upper side of the chamber space 11. The chamber space 11 is made in a vacuum state, and plasma is generated or the generated plasma is flowed into the chamber space 11. The chamber space 11 may have various structures in which a semiconductor process or an etching process is performed. A base block (B) is formed in the chamber space 11, and a susceptor is arranged on the upper part of the base block (B) to fix the wafer (W). The susceptor may be various means for fixing the wafer (W) and may include a heater or a cooling water flow path. The susceptor may include, for example, an electrostatic chuck 12, and an embodiment of an electrostatic chuck will be described below, but the susceptor is not limited thereto. An electrostatic chuck 12 is arranged on the upper side of the base block (B), a heater 121 is arranged inside the electrostatic chuck 12, and a wafer (W) for an etching process is fixed to the upper surface of the electrostatic chuck 12. A lift ring 13 is disposed around the electrostatic chuck 12 to fix the wafer W fixed on the upper surface of the electrostatic chuck 12, thereby maintaining a uniform plasma density and preventing contamination of the wafer W. The lift ring 13 may have the same or similar function as an edge ring, and the edge ring may also serve as the lift ring 13. A heater 131 is disposed inside the lift ring 13 to adjust the temperature of the lift ring 13. The lift ring 13 may support the peripheral portion of the wafer W, and both opposing sides of the lift ring 13 may move up and down by a moving means. As the lift ring 13 supporting the wafer W moves upward, the wafer W may move upward along with the lift ring 13. In this manner, the lift ring 13 may function to move the wafer W upward or downward. The moving means includes linear gears 14a, 14b and lift shafts 15a, 15b that may move along the linear gears 14a, 14b. The first and second linear gears 14a and 14b extend vertically from the bottom surface of the chamber space to the upper side, and meshing teeth may be formed on one surface of the first and second linear gears 14a and 14b along the extension direction of the first and second linear gears 14a and 14b. The lift shafts 15a and 15b may be coupled to the first and second linear gears 14a and 14b so as to be movable up and down. The upper ends of the lift shafts 15a and 15b are coupled to the lower sides of the opposing parts of the lift ring 13, and the lift shafts 15a and 15b may move up and down along the linear gears 14a and 14b by driving the first and second motors (M1 and M2), thereby moving the lift ring 13 up and down. For example, the lift shafts 15a and 15b may include pinion gears meshing with the linear gears 14a and 14b. The lift shafts 15a and 15b may be raised and lowered relative to the linear gears 14a and 14b in various ways, and the present invention is not limited thereto. Electric power for temperature control is supplied to the heater 121 disposed in the electrostatic chuck 12 or the heater 131 disposed in the lift ring 13, and electric power is supplied from the first, second and third power supply means (P1, P2, P3) through the first, second and third cables 16a, 16b and 16c to the electrostatic chuck heater 121 and the lift ring heater 131 to control the temperature of the electrostatic chuck 12 or the lift ring 13. For example, the electrostatic chuck 12 is controlled to a temperature in the range of 20 to 80°C, and the lift ring 13 is controlled to a temperature in the range of 150 to 300°C. Electric power is supplied to both opposing sides of the heater 131 disposed inside the lift ring 13 to control the temperature of the lift ring 13. The heater 131 inside the lift ring 13 may be formed in various ways, for example, a circular heater 131 may be disposed inside the lift ring 13 as a whole, or heaters 131 may be disposed on both sides, and the present invention is not limited thereto.

A cover (C) is attached to the upper surface of the chamber space 11, and an inflow path (P) for guiding plasma from a remote plasma source (RPS) to the inside of the chamber space may be formed in the center of the cover (C). An internal shower head 17a is disposed under the cover (C), and an external shower head 17b is disposed around the internal shower head 17a. The internal shower head 17a or the external shower head 17b may be made of a material such as aluminum, but is not limited thereto. The internal shower head 17a may be disc-shaped or polygonal, or may be flat, and a through hole may be formed in the entire internal shower head 17a from the top to the bottom for the inflow of plasma or gas. A heater 171 is disposed inside the internal shower head 17a, and power is supplied from the power supply means (P4) through a cable 19, so that the temperature of the internal shower head 17a is adjusted to a range of 300 to 400°C. The edge of the internal showerhead 17a is inclined downward, and the external showerhead 17b is disposed outside the internal showerhead 17a. The external showerhead 17b may be inclined outward such that the edge of the internal showerhead 17a is inclined. The external showerhead 17b may have a number of uniform through-holes for guiding plasma or gas to the chamber space 11, as in the internal showerhead 17a. A baffle 18 may be disposed between the internal showerhead 17a and the external showerhead 17b, and at least one slit or through-hole may be formed in the baffle 18 in a horizontal or similar direction. The baffle 18 may be made of, for example, quartz or a similar material, but is not limited thereto. The baffle 18 includes an inclined outer surface, and the inclined outer surface is connected to the inclined surface of the edge of the internal showerhead 17a and the inclined surface of the external showerhead 17b. The baffle 18 can be made of various structures that can prevent radical attack while blocking heat transfer between the internal shower head 17a and the external shower head 17b, but the present invention is not limited thereto. The process of efficiently performing an etching process in an etching process chamber having such a structure will be described later.

Figure 2 illustrates an embodiment of the operating structure of a process chamber according to the present invention.

2, during the etching process, the adsorption process is performed with the wafer (W) positioned above the vacuum chuck 12 as shown in (A), and the removal process is performed with the wafer (W) moved to the upper side as shown in (B). A remote plasma source (RPS) is introduced into the chamber space 11 through an inlet path (P), and ions or radicals for the adsorption process (modification step) are created by the plasma that is introduced from NH ₃ , NF ₃ or Ar present inside the chamber space 11. The wafer (W) is fixed to the upper side of the electrostatic chuck 12. Specifically, the wafer (W) is fixed to a susceptor, which is made of an aluminum material and includes a heater or cooler. The internal showerhead 17a formed on the upper side of the electrostatic chuck 12 may have a function of uniformly flowing the formed ions and radicals to the upper side of the wafer (W) fixed to the susceptor. The temperature of the internal showerhead 17a is maintained at 300 to 400° C. by power supplied to the heater 171 through a cable 19 from a power supply means. The external showerhead 17b may have a function of controlling the process uniformity between the side of the internal showerhead 17a and the surrounding wall of the chamber space 11. Gas may flow toward the side of the internal showerhead 17a or the external showerhead 17b through slits or through holes formed in the baffle 18 along the horizontal direction. The baffle 18 may have a function of blocking the transfer of heat from the internal showerhead 17a to the external showerhead 17b, and is made of quartz or a similar material to prevent attack by radicals. The inner shower head 17a, the outer shower head 17b, and the surrounding wall or cover (C) of the chamber space 11 are made of aluminum or a similar material. The wafer susceptor is made of aluminum or a similar material and is maintained at a temperature of 20 to 80° C. by power supplied to the heater 121 through a cable by a power supply means or by a cooling means. The lift ring 13 is a ring-shaped material made of aluminum or quartz material, and has the heater 131 disposed therein as described above. Power is supplied to the heater 131 from the power supply means through cables 16b and 16c, so that the lift ring 13 is maintained at a temperature of 150 to 300° C. In this state, an adsorption process is performed in the presence of NH ₃ , NF ₃ , and Ar while plasma is supplied from a remote plasma source (RPS) with a power of 500 to 3000 W. The inside of the chamber space 11 may be at about 400° C. in the area of the internal shower head 17a, about 150° C. in the area of the external shower head 17b, about 200° C. in the area adjacent to the wafer (W), about 100° C. in the area below the wafer (W), and about 50° C. in the area of the susceptor. If the adsorption step is completed under these process conditions, the lift pins 13 may be moved upward by the moving means including the linear gears 14a, 14b, the lift shafts 15a, 15b, or the motors (M1, M2). The lift pins 13 contact the wafer (W) to a point about 2 mm from the circumference, and the lift ring 13 rises and contacts the baffle 18. As a result, a removal process space having a narrow size in which a removal step is performed is formed by the internal shower head 17a, the baffle 18, the lift ring 13, and the wafer (W). In this state, the inflow of plasma from the remote plasma source (RPS) is blocked, and the thin film formed on the wafer (W) is removed by Ar present in the removal process space, as shown in FIG. 2B. Ar required for the removal process in the removal process space is introduced into the removal process space through the through holes formed in the internal shower head 17a. After the removal process is completed, the remaining Ar is discharged to the outside through the through holes or slots formed in the baffle 18. The set temperature of the high-temperature internal shower head 17a, the distance between the wafer (W) and the internal shower head 17a, or the temperature of the wafer (W) is appropriately adjusted. In addition, the distance between the internal shower head 17a and the wafer (W), the gas flow capacity of the baffle 18, and the gas flow rate are controlled in the removal process space, and thus the internal pressure of the removal process space is controlled. The internal shower head 17a and the lift ring 13 may have various structures necessary for forming the removal process space and controlling the temperature or pressure, for example, various structures for controlling the gas flow and pressure while restricting the gas flow. Also, as described below, a moving gas wall is disposed on the upper side of the internal shower head 17a in order to improve process uniformity by controlling the gas flow rate and pressure in the removal process space. The internal shower head 17a, the lift ring 13, or the baffle 18 may have various structures capable of controlling the temperature, pressure, space size, or gas flow inside the removal process space, and the present invention is not limited thereto.

Figure 3 illustrates an embodiment of the relative positions of the baffle and lift ring in a process chamber according to the present invention.

Referring to FIG. 3, the lift ring 13 contacts the bottom surface of the baffle 18, or contacts a part of the bottom surface of the baffle 18, or contacts the bottom surface and the inner side of the baffle 18. The linear gears 14a, 14b and the lift shafts 15a, 15b are operated by driving the motors (M1, M2), and the lift ring 13 moves upward and contacts the baffle 18. Referring to FIG. 3B, the lift ring 13 may be ring-shaped as a whole, with the inner part becoming flat, tilting outward in an upward direction, and then becoming flat again. Also, the baffle 18 may have a shape in which the upper side extends flat and then tilts downward. And the lower side of the baffle 18 may be flat. With this structure of the lift ring 13 and the baffle 18, the outer flat surface of the lift ring 13 may contact the bottom surface of the baffle 18, and thus the side of the removal process space is sealed, and gas such as Ar may flow through the through holes formed in the baffle 18.

Referring to FIG. 3B, the baffle 18 extends a relatively large length inwardly of the internal showerhead 17a, and the outer flat surface of the lift ring 13 may contact a portion of the bottom surface of the baffle 18. A gap may be formed between the inner flat surface of the lift ring 13 and the uncontacted flat surface of the baffle 18.

Referring to FIG. 3C, the lift ring 13 may have an inner plane, an inclined plane extending outward, a middle plane, and a step plane formed below the middle plane. The edge of the wafer (W) may contact the inner plane, and the inner plane may have a length of, for example, 2.0 to 3.0 mm. The baffle 18 includes an inner vertical surface and a bottom surface, and a vertical boundary surface formed by the middle plane and the step plane contacts the vertical surface. The bottom surface of the baffle 18 contacts the step plane. With this contact structure, a guide hole connected to the through hole of the baffle 18 may be formed in the lift ring 13. In this way, the lift ring 13 or the baffle 18 may have various structures that can contact each other to seal the side of the removal process space, and the present invention is not limited thereto.

Figure 4 illustrates another embodiment of a shallow etch process chamber according to the present invention.

4, the etching process chamber further includes a movable gas wall 42 that can be raised and lowered to surround the upper part of the internal shower head 17a. As shown in FIG. 4A, the movable gas wall 42 may be located on the upper side of the chamber cover (C) during the adsorption process. The movable gas wall 42 may be a hollow cylinder or a hollow polyhedron surrounding the internal shower head 17a. Gear units 41a and 41b for moving the movable gas wall 42 are disposed at positions facing each other on the movable gas wall 42, and as shown in (B), the gas movable wall 42 may move downward along the gear units 41a and 41b by the operation of the motor (M3). The gas movable wall 42 may be located to surround the upper part of the internal shower head 17a. As a result, the inflow of gas into the removal process space through the through holes formed in the internal shower head 17a is restricted or regulated. Depending on the shape of the internal showerhead 17a of the gas transfer wall 42, it can have a suitable structure and move up and down in various ways, and the present invention is not limited thereby.

Figure 5 illustrates an embodiment of the process by which the ALE process is performed in an etching process chamber according to the present invention.

Referring to FIG. 5, the process of performing the ALE process in the etching process chamber includes a step of placing and fixing a wafer on a susceptor of an electrostatic chuck (P51); a step of controlling the temperature inside the etching process chamber and inducing plasma into the chamber to perform an adsorption process step or a self-limiting deformation process step (P62); a step of lifting the edge ring to form a removal process space above the process chamber when the adsorption process is completed (P53); a step of controlling the temperature of the edge ring, the pressure or gas flow conditions of the removal process space (P54); and a step of performing the removal process using Ar (P55).

A remote plasma source generates ions and radicals for the adsorption process, and a showerhead is disposed so that the ions and radicals flow uniformly toward the wafer. The showerhead is maintained at a temperature of 300 to 400°C, and an external showerhead is disposed between the side of the showerhead and the chamber wall to adjust the process uniformity. A baffle is disposed between the showerhead and the external showerhead to allow gas to flow to the side. The baffle is made of a material such as quartz to prevent attack by radicals while blocking heat transfer. The showerhead, external showerhead, and chamber wall are also made of aluminum. The wafer susceptor is also made of aluminum and may include a heater or a cooling water path for the flow of cooling water. An edge ring on the side of the wafer is made of aluminum or quartz, and a heater is disposed inside the edge ring. An edge ring having such a structure is maintained at a temperature of 150 to 300°C. Under these conditions, plasma is introduced into the chamber to perform the adsorption process (P52). The edge ring includes an edge ring lifting means, and the edge ring is raised to the position of the shower head by the lifting means, while the wafer is lifted (P53). In the adsorption step, the wafer is held at a temperature of 20 to 80° C. while being fixed to the susceptor, and a self-limiting transformation reaction process is performed by ions and radicals generated by a remote plasma source. In the removal step, which is performed in a state where the wafer is raised and a removal process area is formed, the wafer is moved upward by the edge ring in a high temperature state of 150 to 300° C., and can be moved upward to a position where the edge ring contacts the baffle. As a result, the wafer is positioned adjacent to the shower head held at a temperature of 300 to 400° C. In this way, a removal process space is formed by the high temperature shower head, wafer, baffle, and edge ring, and the temperature, pressure, or gas flow conditions of the removal process space are controlled (P14). In the thus formed small-sized removal process space, gas such as Ar for the removal process is filled in the removal process space through the through holes formed in the shower head. Also, such gas is discharged to the outside through the through holes or slits formed in the baffle. The temperature of the wafer is appropriately controlled in the removal step by adjusting the set temperature of the high-temperature shower head and the distance between the wafer and the shower head, and the removal process for removing the thin film formed by the modification process is performed (P55). The pressure of the newly formed removal process space is controlled by the distance between the shower head and the wafer, the gas flow capacity of the baffle, or the gas flow rate. The size of the removal process space or the gas flow rate or pressure is controlled by the shape of the baffle or edge ring in various forms, and the present invention is not limited thereto. Optionally, a moving gas wall may be formed on the upper side of the shower head to improve uniformity. Various configurations for the removal process conditions are added in the removal process space, and the present invention is not limited thereto.

The present invention has been described in detail above with reference to the embodiments presented, but those skilled in the art can make various modifications and alterations without departing from the technical spirit of the present invention by referring to the embodiments presented. The present invention is not limited by such modifications and alterations, but is limited only by the scope of the claims.

11: Chamber space 12: Electrostatic chuck 13: Lift ring 14a, 14b: Linear gears 15a, 15b: Lift shaft 17a: Internal shower head 17b: External shower head 18: Baffle 42: Gas transfer wall 121, 131, 171: Heaters

Claims (8)

a susceptor disposed inside the chamber space 11;
Lift rings 13 formed on both sides of the susceptor;
a moving means for raising and lowering the lift ring 13;
The wafer (W) can be freely raised and lowered above the susceptor by raising and lowering the lift ring 13.
The chamber space 11 further includes an inner shower head 17a and an outer shower head 17b disposed in the upper portion of the chamber space 11. The inner shower head 17a is provided with a shower head heater 171.
The shower head further includes a baffle disposed between the inner showerhead and the outer showerhead.
1. A shallow etch process chamber comprising: The rising lift ring 13 comes into contact with the baffle 18.
10. The shallow etch process chamber of claim 1 . 2. The shallow etch process chamber of claim 1, wherein a process space is formed between the internal showerhead and the wafer by the elevated lift ring. The shallow etch process chamber of claim 1 , further comprising a ring heater disposed within the lift ring. 2. The shallow etch process chamber of claim 1, wherein the moving means comprises linear gears 14a, 14b and lift shafts 15a, 15b movable along the linear gears 14a, 14b. 2. The shallow etch process chamber of claim 1, further comprising an internal showerhead and a movable gas wall that is movable up and down to surround an upper portion of the internal showerhead. The shallow etch process chamber of claim 1 , wherein the baffle (18) defines flow paths. The lift ring 13 is in contact with the bottom surface of the baffle 18, in contact with a part of the bottom surface of the baffle 18, or in contact with the bottom surface and the inner surface of the baffle 18.
3. The shallow etch process chamber of claim 2 .

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