Patent Application
20080296259
This U.S. non-provisional patent application claims priority under 35 U.S.C § 119 of Korean Patent Application 2007-53071 filed on May 31, 2007, the entirety of which is hereby incorporated by reference.
The present invention relates to apparatuses and methods for treating substrates. More specifically, the present invention is directed to apparatus and method for treating a substrate using plasma.
Various processes are required to manufacture a semiconductor device. During a number of processes including deposition, etching, and cleaning processes, plasma is generated from gas and supplied onto a semiconductor substrate such as a wafer to deposit a thin film on the wafer or remove a thin film such as oxide or contaminants from the wafer.
Processes performed using plasma encounter problems as follows:
(1) Since it is difficult to make a density of supplied plasma uniform, etching uniformity or deposition uniformity for respective regions of a wafer is low.
(2) Although a density of supplied plasma is uniform, etching uniformity or deposition uniformity decreases due to various causes such as a chamber configuration.
(3) In the case where a high power is applied to an electrode to increase a density of supplied plasma, electron energy increases and a charge density of electrons is raised on a wafer surface. According when a pattern such as a contact hole is formed by means of an etching process, a shape of the formed pattern does not match a desired shape.
Exemplary embodiments of the present invention are directed to substrate treating methods. In an exemplary embodiment, the substrate treating method may include: providing a substrate inside a housing; and generating plasma from a gas supplied into the housing to treat the substrate, wherein a power for generating the plasma is applied as a pulse during a process, and a magnetic field is provided to a region where the plasma is generated inside the housing.
In another exemplary embodiment, the substrate treating method may include: treating a substrate using plasma, wherein etching rates are measured at respective regions of the substrate while a power for generating the plasma is continuously applied, wherein the direction of a magnetic field provided from magnets disposed outside of a housing where a process is performed is set based on the measuring result, and wherein the power for generating the plasma is supplied as a pulse during the process while the magnetic field is provided in the set direction.
Exemplary embodiments of the present invention are directed to a substrate treating apparatus. In an exemplary embodiment, the substrate treating apparatus may include: a housing in which a space is provided to house a substrate; a support member disposed inside the housing and provided to support the substrate; a gas supply member provided to supply a gas into the housing; a plasma source for generating plasma from the gas supplied into the housing; and a magnetic field formation member provided to form a magnetic field at a region where plasma is generated inside the housing, wherein the plasma source comprises: a first electrode disposed at an upper portion inside the housing; a second electrode disposed at a lower portion inside the housing; a power supply unit for supplying a power to the first electrode; and a source controller for controlling the power supply unit to provide the power applied to the first electrode as a pulse during a process.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention, however, may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the shapes of elements and components are exaggerated for clarity.
In this embodiment, a plasma treating target will now be exemplarily described as a wafer and a plasma treating apparatus using capacitively coupled plasma as plasma source will now be described. However, the embodiments of the present invention are not limited to those mentioned above and the plasma treating target may be another kind of substrate such as a glass substrate, and the plasma source may be inductively coupled plasma.
The equipment front end module 10 is installed in front of the process equipment 20 to carry a wafer W between the process equipment 20 and a container 16 in which wafers W are housed. The equipment front end module 10 includes a plurality of loadports 12 and a frame 14. The container 16 is located on the loadport 12 by transporting means (not shown) such as an overhead transfer, an overhead conveyor or an automatic guided vehicle. The container 16 may be a closed container such as a front opened unified pod (FOUP). A frame robot 18 is installed inside the frame 14 to carry a wafer W between the process equipment 20 and the container 16 located on the loadport 12. A door opener (not shown) is installed inside the frame 14 to automatically open and close a door of the container 16. A fan filter unit (not shown) may be provided at the frame 14. The fan filter unit supplies clean air into the frame 14 to flow from an upper portion to a lower portion in the frame 14.
The process equipment 20 includes a loadlock chamber 22, a transfer chamber 24, and a process chamber 26. The transfer chamber 24 exhibits a polygonal shape, when view from the upside. The loadlock chamber 24 or the process chamber 26 is disposed at the side surface of the transfer chamber 24.
The loadlock chamber 22 is disposed at a side portion adjacent to the equipment front end module 10, among side portions of the transfer chamber 24, and the process chamber 26 is disposed at another side portion. One or at least two loadlock chambers 22 are provided. In an exemplary embodiment, two loadlock chambers 22 are provided. Wafers W put into the process equipment 20 to perform a process may be contained in one loadlock chamber 22, and wafers W processed to be taken out of the process equipment 20 may be contained in the other loadlock chamber 22. Alternatively, one or at least two loadlock chambers 22 may be provided and a wafer may be loaded or unloaded at the respective loadlock chambers 22.
Inside the loadlock chamber 22, wafers are vertically spaced to face each other. A plurality of slots 22a may be provided at the loadlock chamber 22 to support a portion of a wafer edge region.
The insides of the transfer chamber 24 and the process chamber 26 are kept sealed, and the inside of the loadlock chamber 22 is converted to vacuum and atmospheric pressure. The loadlock chamber 22 prevents external contaminants from entering the transfer chamber 24 and the process chamber 26. A gate valve (not shown) is installed between the loadlock chamber 22 and the transfer chamber as well as between the loadlock chamber 22 and the equipment front end module 10. In the case where a wafer W is carried between the equipment front end module 10 and the loadlock chamber 22, the gate valve installed between the loadlock chamber 22 and the transfer chamber 24 is closed. In the case where a wafer W is carried between the loadlock chamber 22 and the transfer chamber 24, the gate valve installed between the loadlock chamber 22 and the equipment front end module 10 is closed.
A process chamber 26 is provided to perform a predetermined process for a wafer W. The predetermined process includes processes using plasma such as, for example, an ashing process, a deposition process, an etching process or a cleaning process. In the event that a plurality of process chambers 26 are provided, each of the process chambers 26 may perform the same process for a wafer W. Optionally in the event that a plurality of process chambers 26 are provided, they may perform a series of processes for a wafer W. Hereinafter, a process chamber 26 performing a process using plasma will be referred to as a plasma treating apparatus.
The support member 220 includes a support plate 222 provided to support a wafer W during a process. The support plate 222 roughly exhibits the shape of a disk. A support shaft 224, which is rotatable by means of a motor (not shown), is fixedly coupled with a bottom surface of the support plate 222. A wafer W may rotate during a process. The support plate 222 may hold a wafer with the use of electrostatic force or mechanical clamping.
The gas supply member 240 is provided to supply a process gas into the housing 200. The gas supply member includes a gas supply pipe 242 connecting a gas supply source with the housing 200. A valve 242a is installed at the gas supply pipe 242 to open and close an internal passage.
The shower head 260 is provided to uniformly distribute a process gas flowing into the housing 200 to an upper region of the support plate 222. The shower head 260 is disposed at an upper portion of the housing 200 to face the support plate 222. The shower head 260 includes an annular sidewall 262 and a circular injection plate 264. The sidewall 262 of the shower head 260 is fixedly coupled with the housing 200 to protrude downwardly from an upper wall of the housing 200. A plurality of injection holes 264a are formed at the entire region of the injection plate 264. The process gas is injected to a wafer W through the injection holes 264a after flowing into a space 266 defined by the housing 200 and the shower head 260.
A lift pin assembly 300 is provided to load a wafer W to the support plate 222 or to unload a wafer W from the support plate 222. The lift pin assembly 300 includes lift pins 322, a base plate 324, and a driver 326. The number of the lift pins 322 provided is three. The three lift pins 322 are fixedly installed at the base plate 324 to move with the base plate 324. The base plate 324 exhibits the shape of a disk and is disposed below the support plate 222 inside the housing 200 or outside the housing 200. The base plate 324 moves up and down by means of the driver 326 such as a hydraulic cylinder or a motor. Through-holes are formed at the support plate 222 to vertically penetrate in an up-down direction. The lift pins 322 are inserted into the through-holes to move down via the through-holes, respectively. Each of the lift pins 322 exhibits the shape of a long rod, and the upper end thereof has an upwardly concave shape.
The plasma source 360 is provided to generate plasma from a process gas supplied to the upper region of the support plate 222. The plasma source 360 employs a capacitively coupled plasma. The plasma source 360 includes a top electrode 362, a bottom electrode 364, a power supply unit 366, and a source controller 368. The injection plate 264 of the shower head 260 is made of a metallic material and may function as the top electrode 362. The bottom electrode 364 is provided at the inner space of the support plate 222. The power supply unit 366 applies a power to the top electrode 362 or the bottom electrode 364. The power supply unit 366 may apply a power to the top electrode 362 as well the bottom electrode 364. Alternatively, a power may be applied to one of the top and bottom electrodes 362 and 364 and the other may be grounded. Further, a bias voltage may be applied to the bottom electrode 364.
The magnetic field formation member 400 is disposed around the housing 200 to provide a magnetic field to a region where plasma is generated.
An electromagnet is used as the respective first magnets 422 and the respective second magnets 442 to control direction and size of a magnetic field. Accordingly, each of the first and second magnets 422 and 442 include coils. In this embodiment, the number of the first magnets 422 provided is eight and the number of the second magnets 442 provided is also eight. The magnets 422 and 442 exhibit the same shape. Each of the magnets 422 and 442 roughly exhibits the shape of rectangular ring and is disposed to stand upright. Inner side surfaces of the magnets 422 and 442 facing the housing 200 are provided flatly. A power 450 is connected to the respective coils provided at the first and second magnets 422 and 442.
A top frame 462 and a bottom frame 464 are provided around the housing 200 to exhibit the shape of octahedron. It appears that a through-hole is vertically formed at the center of the top and bottom frames 462. The first magnet 422 is fixedly installed at an inner side surface of the top frame 462, and the second magnet 442 is fixedly installed at an inner side surface of the bottom frame 464. The first magnets 422 are disposed to be spaced at regular intervals, and the second magnets 442 are also disposed to be spaced at regular intervals. Due to the above-described configuration, each of the first and second magnet units 420 and 440 roughly exhibits the shape of octagon, when viewed from the upside.
The first and second magnetic units 420 and 440 are provided to be asymmetrical with respect to a horizontal surface running therebetween. In an embodiment, the second magnet unit 440 is provided to be in the state of rotating at a predetermined angle from a position where the first and second magnet units 420 and 440 are vertically aligned with each other. The predetermined angle is an angle except multiples of an interior angle of the first magnet unit 420 exhibiting a polygonal shape. The predetermined angle may be, for example, half of an interior angle. As described above, in the case where the first magnetic unit 420 exhibits the shape of octagon, the second magnet unit 440 may be provided to be in the state of rotating at an angle of 67.5 degrees from a position where the first and second magnet units 420 and 440 are aligned with each other. Thus, the second magnets 442 are not aligned with the first magnets 422, and a second magnet 442 is disposed at a vertical lower portion between two first magnets 422.
The power 450 applies current to coils of the first magnet 422 and the second magnet 442, and the magnetic field controller 452 controls the intensity and direction of the applied current.
A rotation member 500 may be further provided at the plasma treating apparatus 26 to rotate the magnet units 420 and 440.
The rotation member 500 rotates the first magnet unit 420 and the second magnet unit 440 at the same time. In an embodiment, the rotation member 500 includes a first pulley 502, a second pulley 504, a belt 506, and a motor 508. A rotation shaft of the motor 508 is fixedly installed at the first pulley 502, and the second pulley 504 is fixedly installed at the circumference of the rotation cover 600. The belt 506 is provided to roll up the first and second pulleys 502 and 504. A rotary force of the motor 508 is transmitted to the rotation cover 600 through the first pulley 502, the belt 506, and the second pulley 504. The rotation member 500 serves to improve a uniformity of plasma density inside the housing 200 during a process. As described in the above embodiment, the rotation member 500 is provided as an assembly including a belt 506, pulleys 502 and 504, and a motor 508. However, the rotation member 500 may be any one of assemblies having various kinds of configurations.
The rotation member 500′ includes a first rotation unit 520 and a second rotation unit 540. The first rotation unit 520 rotates the first rotation cover 620 on its axis, and the second rotation unit 540 rotates the second rotation cover 640 on its axis. The rotation directions of the first and second rotation covers 620 and 640 may be identical to each other, and the rotation speeds thereof may be different from each other. Alternatively, the rotation directions of the first and second rotation covers 620 and 640 may be different from each other.
In the above embodiment, the rotation covers 620 and 640 are provided apart from frames 462 and 464. Alternatively, the frames 462 and 464 may be replaced with the rotation covers 620 and 640 without use of the rotation covers 620 and 640.
While it is described in the above embodiment that “both the first magnet unit 420 and the second magnet unit 640 rotate”, only one of the rotation covers 620 and 640 may rotate.
A typical apparatus uses various parameters to enhance a uniformity of plasma density. Among the parameters, parameters associated with the formment of a magnetic field are the number of electromagnets, the intensity of current applied to the respective electromagnets, and the direction of the applied current. However, this embodiment uses not only such well-known parameters but also additional parameters to make plasma density more uniform. The additional parameters are a misalignment degree (rotation angle) of a second magnet unit 440 to a first magnet unit 420 (they are provided to be partitioned as layers) and a relative rotation speed between the first and second magnet units 440 and 460.
While it is described in the above embodiment that “the magnetic field forming unit 400 includes two magnet units 420 and 460 partitioned as layers”, the magnetic field forming unit 400 may include at least three magnet units 420, 440, and 460, as described in
While it is described in the above embodiment that “the magnet units 420 and 440 include eight magnets 422 and 442, respectively”, the respective magnet units 420 and 440 may include different number of magnets 422 and 442 from the above number. For example, the magnet units 420 and 440 may include four magnets 422 and 442, respectively, as illustrated in
While it is described in the above embodiment that “magnet units are provided to form layers”, a magnetic field formation member may include only one magnet unit 480 provided to form only one layer, as illustrated in
While it is described in the above embodiment that “each magnet is an electromagnet”, each magnet may be a permanent magnet.
While it is described in the above embodiment that “each of the magnet units 420 and 440 is disposed to exhibit the shape of a regular polygon, when viewed from the above”, each of the magnet units 420 and 440 may be disposed to exhibit the shape of polygon or circle.
Various methods for controlling plasma density using the above-described apparatus will now be described below in detail.
In the first embodiment, a method for uniformly providing a plasma density to the entire upper region of a wafer W will now be described. Although the method will be mainly described below in connection with the apparatus illustrated in
It is assumed that, on the basis of any one of the first magnets 422 illustrated in
According to test where both end regions of the diameter of a wafer W and a central region of the wafer W were designated as A, B, and C regions, respectively, when the magnitude of a magnetic field decreased gradually along the A, B, and C regions, plasma density uniformity was excellent in the case where a ratio of a magnetic field magnitude at the A region to a magnetic field magnitude at the B region was within the range between 1.4 and 1.7.
In the case where a high power is applied to a top electrode 362 to increase plasma density, charge density of electrons increases at the surface of a wafer W. This causes a contact hole C to be formed with an undesired shape, as illustrated in
The second embodiment of the present invention provides a method for keeping plasma density high to prevent an etching rate from decreasing and lowering electron energy to decrease charge density to form a pattern with a desired shape on a wafer W. The second embodiment may be practiced using various apparatuses illustrated in
A source controller 368 provides a power supplied to a top electrode 362 as a pulse to suppress increase in electron energy and to decrease electron charge density at the surface of a wafer W. However, as described above, a magnetic field is provided at a plasma-generated region to prevent the disadvantage that the entire power applied to the top electrode 362 is reduced to decrease plasma density. A magnetic field controller 452 controls a power source 450 to continuously apply current to coil of an electromagnet during a process.
Alternatively, as illustrated in
While it is described in the above embodiment “a magnetic field is provided using an electromagnet”, the magnetic field may be provided using a permanent magnet.
While it is described in the above embodiment that “a power is applied to a top electrode 362”, a power-receiving target is variable with kinds of sources provided to generate plasma.
Although plasma density is uniformly provided at the entire region on a wafer W, an etching rate may vary with regions of the wafer W due to various causes such as shape or inner components of a housing 200. In the third embodiment, there is provided a method for differently providing plasma density to respective regions on a wafer W to improve an etching uniformity. While this embodiment will now be described by exemplarily using the apparatus illustrated in
According to this embodiment, plasma density is uniformly provided inside a housing 200 to measure etching rates relative to respective regions of a wafer W during a process. Directions of magnetic fields provided from electromagnets 482 are set based on the measuring result. In the case where an etching rate at a central region of a wafer W is lower than that at the edge region of the wafer W (see
As shown in
When a power is applied to the top electrode 362, an electric field is formed between the top electrode 362 and a bottom electrode 364 inside the housing 200 and, as shown in
In the case where an etching rate at an edge region of a wafer W is lower than that at a central region of the wafer W, as shown in
As shown in
When a power is applied to the top electrode 362, an electric field is formed between the top electrode 362 and a bottom electrode 364 inside the housing 200 and, as shown in
While it is described in the above embodiment that “electromagnets are used as magnets”, permanent magnets may be used as the magnets.
According to the present invention, plasma density is uniformly provided inside a housing and an etching uniformity is improved at the entire region of a wafer. In addition, the plasma density is controllable along regions inside the housing.
Although the present invention has been described in connection with the embodiment of the present invention illustrated in the accompanying drawings, it is not limited thereto. It will be apparent to those skilled in the art that various substitutions, modifications and changes may be made without departing from the scope and spirit of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2007-0053071 | May 2007 | KR | national |
