KR20040088628A - Inductively-coupled plasma source producing uniform plasma by using multi-coils - Google Patents

Abstract

PURPOSE: An inductively-coupled multi-coil plasma source for providing uniform plasma is provided to maximize uniformity of magnetic field by maximizing the intensity of inductive magnetic field within a limited area. CONSTITUTION: An inductively-coupled multi-coil plasma source includes a first inductive coil, a plurality of second inductive coils, and a power supply. The second inductive coils(250) are arranged around the outside of the first inductive coil(210). The second inductive coils facing the first inductive coil are parallel to the first inductive coil. The power supply(410) is used for supplying the power to the first inductive coil and the second inductive coils in order to provide the inductive magnetic field enabling the first inductive coil and the second inductive coils to generate plasma.

Description

Inductively-coupled plasma source producing uniform plasma by using multi-coils}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus, and more particularly, to an inductively coupled multi-coil plasma source which can have a maximum coil area in a semiconductor manufacturing chamber and provides a uniform plasma. It is about.

At present, many improvements in the process have been made by introducing plasma into semiconductor manufacturing processes, in particular etching or deposition processes. In addition, many attempts have been made to generate high density plasma and improve plasma uniformity. One example of such attempts is Inductively Coupled Plasma (ICP).

Examples of such inductively coupled plasma sources are described in US Pat. No. 54,358,81 ("Apparatus for producing planar plasma using varying magnetic poles" by John S. Ogle, registered July 25, 1995) or US Pat. No. 6,273,022 B1 (Bryan Y). Pudis et al., "Distributed inductively-couped plasma source", registered August 14, 2001. These documents seek to improve the inductively coupled plasma source by arranging a plurality of induction coils.

Although improvements to inductively coupled plasma sources have been attempted, there is still a need for improvements to non-uniformity of induction magnetic fields implemented by induction coils. In particular, it is recognized that the nonuniformity of the radial plasma should be further improved. Radial plasma nonuniformity is mainly due to the phenomenon that the induced magnetic field is not evenly distributed radially. When the induced magnetic fields of the center and the outer portion of the plasma source become uneven, the generated plasma is not evenly distributed radially, and the uniformity of the plasma is significantly reduced.

Thus, in order to increase the uniformity of the plasma, the inductively coupled plasma source must provide a more radially uniform induced magnetic field. Accordingly, there is an urgent need for an inductively coupled plasma source capable of providing a more uniform induction magnetic field as well as azimuthally. In particular, since the semiconductor manufacturing process currently requires a large diameter wafer having a 300 mm diameter, there is an urgent need for the development of an inductively coupled plasma source capable of providing such a radially uniform induction magnetic field.

SUMMARY OF THE INVENTION The present invention provides an inductively coupled multi-coil plasma source capable of providing a uniform plasma with an induction coil arrangement that maximizes the intensity of the induction magnetic field and maximizes the uniformity of the induction magnetic field within a given area. There is.

1 is a cross-sectional view schematically illustrating a state in which an inductively coupled plasma source is installed in a chamber according to an embodiment of the present invention.

FIG. 2 is a plan view schematically illustrating the arrangement between the first induction coil and the second induction coil constituting the inductively coupled plasma source according to an embodiment of the present invention.

3 is a perspective view schematically illustrating a state in which a first induction coil and a second induction coil constituting an inductively coupled plasma source according to an exemplary embodiment of the present invention are wound.

4A and 4B are plan views schematically illustrating power supply states of a first induction coil and a second induction coil constituting an inductively coupled plasma source according to an embodiment of the present invention.

5 to 10 are schematic plan views illustrating modifications of the arrangement of the first induction coil and the second induction coil constituting the inductively coupled plasma source according to the embodiment of the present invention.

11 and 12 are wafer maps schematically illustrated to explain the effects that can be realized by an inductively coupled plasma source according to an embodiment of the present invention.

One aspect of the present invention for achieving the above technical problem, can provide an inductively coupled multi-coil plasma source capable of maximizing the intensity of the induction magnetic field in a given area and maximizing the uniformity of the induction magnetic field. The inductively coupled plasma source includes a plurality of second induction coils and a plurality of second induction coils arranged so as to surround an outer portion of the first induction coil and the coil portions opposed to the first induction coil are parallel to the first induction coil. Coils, and the first induction coil and the second induction coil may include a power supply for supplying power to provide an induction magnetic field for generating a plasma.

Here, the first induction coil may be a coil wound to form a circle. Alternatively, the first induction coil may be a coil wound to form a polygon or a regular polygon. In this case, the second induction coils are arranged by the number corresponding to the sides of the first induction coil constituting the polygon or the regular polygon, and each of the second induction coil has a coil portion facing the side of the first induction coil It may be a coil wound to be parallel to.

The induction coil may be a solenoid coil, a flat spiral coil, or a coil wound in a form in which a solenoid type and a flat spiral are mixed. In addition, the first induction coil may be a coil wound down so that the inlet end connected to the power supply unit is located on the upper side opposite to the generated plasma and the outlet end to be grounded is located on the lower side. Alternatively, the first induction coil may be a coil wound in such a manner that the lead end connected to the power supply unit and the lead end to be grounded are located on the upper side opposite to the plasma to be generated. In addition, the second induction coil may be a coil wound so that coil portions facing each other between the second induction coils are parallel to each other. In this case, the diameter of the first induction coil may be 1/2 to 1/4 of the diameter of the entire outer circumference including the second induction coil and the first induction coil. The inductively coupled plasma source may further include a magnetic core inserted into the center of each of the induction coils.

On the other hand, the power supply unit generates the magnetic field of the opposite polarity of the second induction coil adjacent to each other and the first induction coil and the second induction coil to generate a magnetic field of any one polarity Or supply the power. Alternatively, the two adjacent second induction coils may be formed of coils wound in opposite directions to each other so that the second induction coils generate magnetic fields having opposite polarities.

According to the present invention, it is possible to provide an inductively coupled multi-coil plasma source capable of providing a radially uniform plasma with an induction coil arrangement that maximizes the intensity of the induced magnetic field within a given area and maximizes the uniformity of the induced magnetic field. Can be.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and the like of the elements in the drawings are exaggerated to emphasize a more clear description, and the elements denoted by the same reference numerals in the drawings means the same elements.

Embodiments of the present invention provide an inductively coupled plasma source in which induction coils are arranged to provide a more uniform induction magnetic field to maximize the uniformity of the plasma generated by the induction magnetic field. Such an inductively coupled plasma source can be mounted in a chamber for semiconductor manufacturing and used effectively to use a 300 mm large diameter wafer. Such an inductively coupled plasma source comprises a plurality of second induction coils arranged around the first induction coil and the first induction coil, in particular in order to improve the uniformity of the plasma in azimuth, On opposite sides of the second induction coils and the first induction coil, these coils are arranged parallel to each other. As the first induction coil and the second induction coil are arranged in parallel with each other on opposite surfaces, the induced magnetic field can be generated very uniformly from the center to the outer direction, that is, radially. Since a radially uniform induced magnetic field may occur, the plasma generated thereby becomes very uniform.

1 is a cross-sectional view schematically illustrating a state in which an inductively coupled plasma source is installed in a chamber according to an embodiment of the present invention. 2 is a plan view schematically illustrating the arrangement of the first induction coil and the second induction coil according to an embodiment of the present invention. 3 is a perspective view schematically illustrating a state in which a first induction coil and a second induction coil according to an exemplary embodiment of the present invention are wound. 4A and 4B are plan views schematically illustrating power supply states to a first induction coil and a second induction coil according to an embodiment of the present invention.

1 and 2 together, an inductively coupled plasma source according to an embodiment of the present invention may be installed above the chamber 100. The chamber 100 provides a space in which a wafer 150 to be subjected to a semiconductor manufacturing process, for example, an etching process, for example, a wafer 150 having a 300 mm diameter is mounted. The chamber 100 may be sealed by the chamber lid 101 to implement a vacuum. The chamber lid 101 may be made of an insulator in the form of a disc. In addition, RF (Radio Frequency) power may be provided on the back side of the wafer 150 depending on the process.

The inductively coupled plasma source is basically composed of a first induction coil 210 in the center and a plurality of second induction coils 250 arranged around the first induction coil 210 as shown in FIG. 2. Can be. These induction coils 210 and 250 are introduced while being wound around the respective coil supports 310 and 350. The coil supports 310 and 350 are mounted on the source support plate 390 to be coupled in the form of substantially one plasma source. The source support plate 390 is mounted on the chamber lid 101 so that an inductively coupled plasma source is located above the chamber 100. The chamber 100 is further provided with a cover 105 covering the inductively coupled plasma source.

The induction coils 210 and 250 are connected to a power supply unit 410 to which electric power for generating an induction magnetic field is supplied. The power supply unit 410 may include an AC current generator or an RF generator. The power supply 410 supplies induction coils 210 and 250 with different phases of electricity to allow the induction coils 210 and 250 to generate magnetic fields of the same or different polarity. To provide such a phase difference, the power supply unit 410 and the induction coils 210 and 250 may be electrically connected in various circuit forms. That is, various matching networks 450 may be configured between the power supply 410 and the induction coils 210 and 250. Such a basic configuration may be described by the present invention in Korean Patent Application No. 2002-65178 ("Dry etching semiconductor manufacturing apparatus", filed October 24, 2002) by the applicant.

Referring to FIG. 2, the first induction coil 210 is positioned at the center portion, and the second induction coils 250 are disposed to surround the first induction coil 210. In this case, the coils in the portions in which the first induction coil 210 and the second induction coil 250 face each other, for example, 201 of FIG. 2, are parallel to each other. That is, when the first induction coil 210 is wound around the first coil support 310 to form a regular octagon, as shown in FIG. 2, a portion of the first induction coil 210 constituting the side of the regular octagon 201. And portions of the second induction coil 250 opposite to the side 201 are introduced in parallel to each other.

As described above, in order for the two induction coils 210 and 250 to be parallel to each other at a predetermined portion, the shape of the coil supports 310 and 350 may be adjusted accordingly. That is, as shown in FIG. 3, the first coil support 310 is formed in a square octagonal pillar shape, and a coil groove (conductive layer) for the coil is formed on the side thereof, and then the coil groove (conductive layer) is formed. A coil, for example, a copper wire having a diameter of 2 mm may be wound so that the first induction coil 210 may have a square octagonal shape. In addition, the second coil support part 350 may correspond to a polygonal shape having a side surface corresponding to the side surface of the first coil support part 310, for example, a quadrilateral quadrangular pillar shape as shown in FIG. 3. The coil groove 351 is also provided on the side surface of the second coil support 350, and the coil is wound around the coil groove 351 to implement the second induction coil 250.

In this case, as shown in FIG. 3, the side of the first coil support 310 and the side of the second coil support 350 face each other in parallel to each other, such that the first induction coil 210 and the second induction coil 250 are in parallel with each other. The sides are opposed to each other in parallel.

The second coil support part 350 for the second induction coil 250 is installed when the first coil support part 310 is formed in a regular polygon or polygonal shape such as a regular octagon, and is provided as many as the number of sides of the regular polygon or polygon. do. In this case, each of the second coil supports 350 may have an equilibrium between the second induction coils 250, which are opposite to the first induction coil 210, as shown in FIG. 2. Installed to implement At this time, it is preferable that the separation interval between the first induction coil 210 and the second induction coil 250 is as small as possible. In addition, it is preferable to minimize the spacing between the second induction coils 250 as well.

As such, when the first induction coil 210 and the second induction coil 250 are parallel to each other, there is an advantage in that the magnetic field distribution is more evenly distributed radially from the center to the outside. If the first induction coil and the second induction coil are not parallel and are sharply opposed at only one freezing point, for example, if the second induction coil is a wedge-shaped coil, it is different from the radial direction passing through the end of the wedge. The induced magnetic field distribution between the radial directions can vary. It can be understood that this results in severe non-uniformity of the magnetic field distribution. However, in the embodiment of the present invention, as described above, the first induction coil 210 and the second induction coil 250 may be parallel to each other to induce a more uniform radial magnetic field distribution. At this time, the opposite portions between the second induction coils 250 are also parallel to each other, which is more advantageous for a more uniform magnetic field distribution.

Meanwhile, referring again to FIG. 2, the first induction coil 210 generates a magnetic field of N polarity by the applied RF power, and the surrounding second induction coils 250 generate magnetic fields of different polarities. Let's go. The generation of the magnetic field may be sequentially changed by the phase of the RF power supplied from the power supply 410. For example, when the RF power is applied at 13.56 MHz, when the phase difference between the second induction coil 250 and the first induction coil 210 is approximately 90 ° to each other, the first induction coil 210 and the second Magnetic fields of different polarities may be generated between the induction coils 250. In addition, when the second induction coils 250 are supplied with such a phase difference, magnetic fields having different polarities may be sequentially generated. Alternatively, even when the second induction coils 250 are wound in opposite directions with each other in the same phase, magnetic fields having different polarities may be sequentially generated.

Meanwhile, referring back to FIGS. 2 and 3, the first induction coil 210 may influence the uniformity of the induction magnetic field generated by the inductively coupled plasma source according to the method of winding the first coil support 310. Can be. As shown in FIG. 3, when the first induction coil 210 is wound on the first coil support part 310, the coil is first lowered from the upper side to the lower side and then wound up again to rewind the induction end of the first induction coil 210. 211 and the lead end 215 may be of equal height and guided to extend in the same direction. RF power is supplied to the lead end 211, and the lead end 215 extends to the chamber 100 or the cover 105 to be grounded. In this way, if both the inlet end 211 and the lead end 215 can be extended to the upper side of the first induction coil 210, the induction is formed below the first induction coil 210 or the second induction coil 250 The influence on the magnetic field can be minimized.

4A and 4B, FIG. 4A illustrates a state where the lead end 215 of the first induction coil 210 is installed at the same height or in the same direction as the lead end 211 as described above. . On the contrary, in FIG. 4B, the inlet end 211 and the outlet end 215 ′ are implemented at different heights. In this case, unlike the case illustrated in FIG. 3, the first induction coil 210 is wound down from the upper side to the lower side. Corresponds to the case where the coil is wound around the first coil support 310. In this case, the lead end 215 ′ is forced to be drawn out below the first induction coil 210 under the second induction coil 250, thereby affecting the induced magnetic field.

In contrast, in the case of the second induction coil 250, although the inlet end 251 and the outlet end 255 are implemented at different heights, the induction end 255 may be drawn out and grounded without passing through the generated magnetic field. have. Therefore, the second induction coil 250 may be wound around the second coil support part 350 in a winding down manner.

Meanwhile, referring back to FIG. 3, it is preferable that the first and second coil supports 310 and 350 are implemented in a frame form so as to implement a space therethrough. This is because the induction coils 210 and 250 are more advantageous in dissipating heat that may be generated in the operation of generating the induction magnetic field.

Until now, the first induction coil 210 is embodied in an octagonal shape when viewed in a plan view, and the second induction coil 250 is equal to the number of sides of the regular octagon around the first induction coil 210 in an equivalent plane. In the following, the embodiments of the present invention have been described with reference to the introduction of the elements in parallel, but the present invention may be embodied in various forms.

5 to 10 are schematic plan views illustrating modifications to the arrangement of the first induction coil and the second induction coil according to an embodiment of the present invention.

5 to 8, the first induction coil 210 and the second induction coil 250 may be modified in various forms as long as the coils in the opposing portions maintain the parallel state as shown. The first induction coil 210 and the second induction coil 250 are designed in such a manner that the sum of the induction coil cross sections per unit area is the largest in designing a plurality of coils in a given limited area in plan view. It is preferable.

Since the magnetic field induced by the induction coil is proportional to the induction coil cross-sectional area, the first induction coil 210 may be introduced in a octagonal shape as shown in FIG. 2, and the second induction coil 250 may be introduced accordingly. However, as shown in FIGS. 5, 6, and 7, the first induction coil 210 may have a regular polygonal shape of a regular hexagon or a regular tetragonal shape. In addition, although not shown, the first induction coil 210 may be implemented in a polygonal shape. In addition, correspondingly, the second induction coil 250 may be variously presented, and the outer portion of the second induction coil 250 may also be circular as shown in FIGS. 5 and 6 or as shown in FIG. 7. It may be implemented as a square or a square to suit a liquid crystal display.

Furthermore, as shown in FIG. 8, the first induction coil 210 may be implemented in a circular shape, and accordingly, the second induction coil 250 may be concave to correspond to the first induction coil 210. It may be. In this case, the winding of the second induction coil 250 in a concave shape is somewhat difficult to implement the coil support, but is not impossible.

As described above, the first induction coil 210 and the second induction coil 250 may be implemented in various planar shapes as long as the portions facing each other are parallel to each other, but the diameter of the first induction coil 210 may vary. It is preferable to maintain the uniformity of the actual induced magnetic field in the range of 1/4 to 1/2 times the diameter with respect to the entire outer circumference. In practice, it is preferable that the diameter of the first induction coil 210 is about 2/5 times that of the total outer circumference.

The first induction coil 210 and the second induction coil 250 described above have been described in a state in which a magnetic core is not introduced therein. The present invention proposes a unique coil arrangement in which the induction coil area per unit area is maximum, so that a magnetic field corresponding to a single coil can be generated without a magnetic core. In addition, in the case of the multiple induction coil arrangement as described in the embodiments of the present invention, it is possible to improve the uniformity which cannot be achieved in a single coil by using a plurality of induction coils. In addition, the magnetic polarity of the neighboring coils is reversed to generate a magnetic field in the neighboring coil direction instead of the wafer direction, thereby reducing wafer damage by reducing the magnetic transmission distance in the wafer direction. Therefore, high uniformity and low magnetic transmission distance, which are advantages of the multiple induction coil, can be maintained without causing heat generation and uniformity deterioration due to the introduction of the magnetic core.

Nevertheless, such multiple induction coil arrangements are difficult to increase the induction coil area per unit area by more than a single coil due to the use of multiple induction coils. Therefore, it is substantially very difficult to avoid the occurrence of relatively magnetic field loss. Therefore, the magnetic cores 910 and 950 as shown in FIG. 9, such as ferrite cores, as shown in FIG. You can insert

Multiple magnetic cores 910 and 950 may be inserted into one coil. In this case, the magnetic cores 910 and 950 are preferably ones of the same material and size, which is a cause of deterioration of the uniformity of the magnetic field if the magnetic cores 910 and 950 are not the same material and size. Because it may be. While the magnetic cores 910 and 950 have an advantage of increasing the magnetic field, they are disadvantageously generated by induction heating due to being present in the induction coil. Such heat generation can be compensated for by easily inducing heat dissipation of the coil supports 310 and 350 having a frame shape as shown in FIG. 3.

The first induction coil 210 and the second induction coil 250 so far have been described using coils wound in a solenoid form as described with reference to FIG. 3. However, the inductively coupled plasma source according to the embodiment of the present invention can use the coils wound in the form of the solenoid as the first induction coil 210 and the second induction coil 250, as shown in FIG. 10. The first induction coil 210 'and the second induction coil 250' wound in a planar spiral shape may also be configured.

Even in this case, opposing portions of the first induction coil 210 'and the second induction coil 250' are introduced in parallel, and also the second induction coil 250 'is introduced in parallel with each other. In addition, although the entire outer shape is presented in a square shape in FIG. 10, as described above, as long as it maintains the parallel state as described above, it may be modified into various shapes as necessary.

In some cases, coils wound in a form in which a solenoid shape and a planar spiral shape are mixed may be used as the first induction coil 210 'and the second induction coil 250'.

11 and 12 are wafer maps schematically illustrated to explain the effects realized by the inductively coupled plasma source according to an embodiment of the present invention.

11 and 12 show an etching process on a 300 mm wafer using an inductively coupled plasma source comprising a first induction coil 210 and a second induction coil 250 as shown in FIG. These are the maps obtained on the wafer. FIG. 11 illustrates a case in which the first induction coil 210 is rolled down and then rolled up again to the first coil support 310 as described with reference to FIG. 3 to implement the first induction coil 210. Is a case where the first induction coil 210 is implemented only by winding down.

Referring to the results of FIGS. 11 and 12, it can be seen that the map of FIG. 11 has higher etching uniformity than the map of FIG. 12. The results in FIG. 11 show low nonuniformity (min-max) of approximately ± 1% and the results of FIG. 12 show relatively high nonuniformity of about ± 7%. The result of FIG. 12 indicates that the etch rate from the lead end to the ground end is low, and thus, the downward winding method as shown in FIG. 4B is disadvantageous in improving the uniformity. In addition, the results of FIG. 11 show that very high etching uniformity can be realized by the embodiment of the present invention, and thus, it can be proved that very high induced magnetic field uniformity can be realized by the embodiment of the present invention. In addition, in the case of the second induction coil 250, both the down winding method and the down winding up and down, the influence of the etching nonuniformity appears to be insignificant.

As mentioned above, although this invention was demonstrated in detail through the specific Example, this invention is not limited to this, It is clear that the deformation | transformation and improvement are possible by the person of ordinary skill in the art within the technical idea of this invention.

According to the present invention described above, by making a unique coil arrangement in which the induction coil area per unit area is maximum, a magnetic field corresponding to a single coil can be generated without introducing a magnetic core. In addition, since the portions in which the first induction coil and the second induction coil face each other are introduced in parallel, the uniformity of the induced magnetic field can be extremely increased radially. Therefore, high etch uniformity or induced magnetic field uniformity, plasma uniformity and low magnetic transmission distance can be maintained as it is. Therefore, the processing capability can be greatly improved even on a semiconductor substrate having a 300 mm diameter.

Claims (11)

A first induction coil; A plurality of second induction coils disposed to surround the outer side of the first induction coil and wound so that a coil portion opposed to the first induction coil is parallel to the first induction coil; And And a power supply for supplying power to the first induction coil and the second induction coil to provide an induction magnetic field for generating a plasma. The method of claim 1, And said first induction coil is a coil wound to form a circle. The method of claim 1, And the first induction coil is a coil wound to form a polygon or a regular polygon. The method of claim 3, The second induction coils are arranged in a number corresponding to the sides of the first induction coil forming the polygon or the regular polygon, and each of the second induction coils has a coil portion opposed to the sides of the first induction coil. An inductively coupled plasma source, characterized in that it is a coil wound in parallel. The method of claim 1, The inductively coupled plasma source of the induction coil is a solenoid coil, a flat spiral coil or a coil wound in a form in which the solenoid type and the flat spiral are mixed. The method of claim 1, The first induction coil is an inductively coupled plasma source characterized in that the inlet end connected to the power supply unit is coiled by winding down so that the inlet end to be grounded is located on the upper side opposite to the generated plasma. . The method of claim 1, The first induction coil is a coil wound in such a way that the lead end connected to the power supply unit and the lead end to be grounded are wound down and rewinded so as to be positioned on an upper side opposite to the plasma to be generated. Plasma source. The method of claim 1, And the second induction coil is a coil wound so that coil portions facing each other between the second induction coils are parallel to each other. The method of claim 1, Inductively coupled plasma source, characterized in that the diameter of the first induction coil is 1/2 to 1/4 of the diameter of the entire outer circumference including the second induction coil and the first induction coil. The method of claim 1, And a magnetic core inserted into a center of each of the induction coils. The method of claim 1, The power supply unit may generate magnetic fields having opposite polarities to each other where the second induction coils are adjacent to each other, and the first induction coil may generate magnetic fields of any one polarity to the first induction coil and the second induction coils. Supply the power or Or the two adjacent second induction coils are composed of coils wound in opposite directions so that the second induction coils generate magnetic fields of opposite polarity to one another.