TW201349334A - Plasma processing device and inductive coupling coil thereof - Google Patents

Abstract

The present invention discloses a plasma processing device and an inductive coupling coil thereof. In the inductive coupling coil of the plasma processing device, the single-turn spiral coil structure of the prior art is modified to have a plurality of ring sections comprising multiple 1/2, 1/4 or 1/6 circular rings, and the connection means for the ring sections are improved, so that the directions of the radio frequency currents of the radially adjacent ring sections of the coil are opposite; therefore, the distribution of plasma generated in a reaction chamber along a radial direction above a wafer will be more uniform, which is suitable for processing a wafer with a larger diameter.

Description

Plasma processing device and its inductive coupling coil

The present invention relates to the field of semiconductor manufacturing equipment, and in particular to an inductive coupling coil and a plasma processing apparatus provided with the inductive coupling coil.

At present, inductively coupled plasma processing devices are widely used in the manufacturing process of semiconductor devices. In a plasma processing apparatus as shown in FIG. 1, an electrostatic chuck 6 is disposed at the bottom of the reaction chamber 4, and the wafer 5 waiting for processing is placed on the electrostatic chuck 6. An inductive coupling coil (hereinafter referred to as coil 3) is disposed above the outer side of the top plate of the reaction chamber 4.

In the semiconductor processing process, the first RF source 1 is connected to the coil 3 through the first matching unit 2, the supplied RF current flows into the coil 3, and a magnetic field is generated around the coil 3, thereby generating an electric field in the reaction chamber 4. Thereby, the process gas introduced into the reaction chamber 4 is ionized and a plasma is generated. The surface of the wafer 5 is etched or the like by the generated plasma. At the same time, the second RF source 11 is also connected to the electrostatic chuck 6 through the second matching device 10, and is used to provide a bias voltage after the RF power source is turned on, so as to increase the energy of ions colliding with the wafer 5 by the plasma.

As shown in FIG. 2, it is a commonly used inductive coupling coil, which is a planar spiral structure, and is generally composed of a single-turn spiral wound conductive coil. Since the current directions of the two ring segments adjacent in the radial direction of the coil are the same when the RF current flows through the coil, it is easy to form a non-uniform donut-shaped magnetic field in the reaction chamber (see Figure 8 shows the dotted line).

That is, the intensity of the electromagnetic field induced in the reaction chamber near the center of the coil, It is greater than the electromagnetic field strength at the edge of the coil or other locations, and therefore, the density of the plasma above the wafer is low at the center high edge, and the uneven distribution of the plasma along the radial direction is difficult to eliminate by diffusion. This will result in uneven distribution of the etching process on the surface of the wafer, affecting the quality of the finished product of the semiconductor device.

In addition, if the processing of larger diameter wafers is required, it is necessary to increase the length and number of turns of the inductive coupling coil. Moreover, for larger diameter wafers, the above-described plasma is unevenly distributed in the radial direction. Therefore, it is difficult to satisfy the requirement for uniform distribution of large-area, high-density plasma by the formation of the existing spiral inductive coupling coil, and it is not suitable for uniform etching for large-sized wafers.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel structure of an inductively coupled coil having opposite current directions in adjacent loops of the coil such that plasma generated in the reaction chamber can be more evenly distributed radially above the wafer. In order to adapt to the processing of larger diameter wafers. The present invention also provides a plasma processing apparatus in which the inductive coupling coil is disposed.

In order to achieve the above object, the present invention provides an inductive coupling coil, and a plasma processing apparatus using the same. The plasma processing apparatus includes a reaction chamber, an electrostatic chuck is disposed at a bottom of the reaction chamber, the inductive coupling coil is disposed above an outer side of a top plate of the reaction chamber; and a first RF source is connected a first matching device, providing a radio frequency current to the coil to generate an electromagnetic field, thereby ionizing a process gas introduced into the reaction chamber to form a plasma, and the wafer placed on the electrostatic chuck through the plasma Process it.

Wherein the inductive coupling coil is a planar structure coil, wherein the coil is provided with a plurality of electrically conductive ring segments arranged radially spaced apart from each other, wherein any two of the RF currents flowing on the radially adjacent ring segments are The direction is the opposite.

The coil is provided with N ring segments, and N is an even number; Each of the ring segment groups includes a plurality of the ring segments having the same opening direction and decreasing in radius; each of the ring segments is one-ninth of a ring.

a second end of each of the ring segment groups having a first radius, and a first end of a ring segment having a second radius in an adjacent one of the ring segment groups, through the conductive connecting segment Connecting; the first radius is different from the second radius, and two ring segments having a first radius and a second radius in each of the ring segment groups are adjacently disposed in a radial direction of the coil.

When the first radius or the second radius is the minimum radius of the coil, the second end of the ring segment having the smallest radius of each of the two ring segment groups is no longer with the first end of the other ring segments. Connect, but connect the second ends of the two ring segments directly through the connecting segments.

When the first radius or the second radius is the maximum radius of the coil, the first end of the ring segment having the largest radius among all the ring segment groups is no longer connected with the second end of the other ring segments; any two of them In the ring segment group, the first ends of the ring segments having the largest radius respectively serve as the input end and the output end of the RF current of the coil; and, in each of the other two ring segment groups, the ring segments having the largest radius respectively The first end is connected directly through the connection segment.

The present invention also provides an inductive coupling coil, and a plasma processing apparatus using the inductive coupling coil. The plasma processing apparatus includes a reaction chamber, an electrostatic chuck is disposed at a bottom of the reaction chamber, and the inductive coupling coil is disposed above an outer side of a top plate of the reaction chamber; a first RF source passes Connecting a first matching device, providing an RF current to the inductive coupling coil to generate an electromagnetic field, thereby ionizing a process gas introduced into the reaction chamber to form a plasma, and placing the plasma pair on the electrostatic chuck The wafer is processed; wherein the inductive coupling coil is a planar structure coil, the coil is provided with a plurality of semi-circular segments, and each of the two semi-circular segments has a uniform radius and opposite openings; all semicircles The ring segments are divided into two groups, and each of the half ring segments has the same opening direction, a decreasing radius, and is arranged at a radial interval; Except for the first end of the half-ring segment having the largest radius in the two groups, and the second end of the semi-ring segment having the smallest radius among the two groups, the other end of the other half of the semi-annular segment having the first radius a first end of a semi-annular segment having a second radius opposite the opening, connected by a connecting segment; the first radius being different from the second radius and having a first radius and a second in the same group The two half ring segments of the radius are arranged adjacent to each other in the radial direction of the coil; the half ring segments having the smallest radius among the two groups, the respective second ends are directly connected by the connecting segments; and the half ring segments having the largest radius among the two groups The respective first ends are respectively used as the input end and the output end of the radio frequency current, and the direction of the radio frequency current flowing on any two of the radially adjacent ring segments on the coil is opposite.

Compared with the prior art, the plasma processing apparatus and the inductive coupling coil thereof of the present invention have the advantages that in the inductively coupled plasma processing apparatus, the originally used single-turn helical coil structure is changed to have several groups. a ring segment containing a plurality of 1/2, 1/4 or 1/6 rings, and an improvement in the wiring of the ring segments such that the RF currents of the radially adjacent ring segments on the coil are opposite in direction. The plasma generated in the reaction chamber is more evenly distributed in the radial direction above the wafer, and can be adapted to process larger diameter wafers.

1‧‧‧First RF source

10‧‧‧Second matcher

11‧‧‧second RF source

2‧‧‧First matcher

20‧‧‧Dielectric layer

3‧‧‧ coil

31‧‧‧Inductive Coupling Coil

32‧‧‧Inductive Coupling Coil

33‧‧‧Inductive Coupling Coil

4‧‧‧Reaction chamber

41‧‧‧First ring segment

42‧‧‧second ring segment

43‧‧‧ Third ring segment

5‧‧‧ Wafer

51‧‧‧ Connection section

52‧‧‧Connection section

53‧‧‧ Connection section

6‧‧‧Electrostatic chuck

B‧‧‧Magnetic induction

Q‧‧‧ intersection

1 is a schematic structural view of a conventional inductively coupled plasma processing apparatus; FIG. 2 is a schematic structural view of a conventional inductive coupling coil; FIG. 3 is a schematic structural view of the inductive coupling coil of the present invention in Embodiment 1; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 5 is a schematic structural view of the inductive coupling coil of the present invention in Embodiment 3; FIG. 6 is a schematic view of the inductive coupling coil of the plasma processing apparatus of the present invention; Schematic diagram of current flow direction and magnetic field distribution; FIG. 7 is an enlarged schematic view of the leftmost two turns of the magnetic induction line in FIG. 6 for explaining the principle of magnetic field intensity superposition; FIG. 8 is an inductive coupling coil and an existing coil phase using the present invention. Ratio, electromagnetic field strength and Schematic diagram of the relationship of the radial position on the reaction chamber.

As shown in FIG. 3, it is a specific implementation structure of the inductive coupling coil of the present invention. The coil 31 is a planar double inverted coil (reversed double spiral coils), that is, the coil 31 is provided with multiple approximations. The first ring segment 41 of the semi-annular ring has a uniform radius and an opposite opening. Each of the first ring segments 41 having the same opening direction and decreasing in radius is grouped into a group, and each of the first ring segments 41 is radially spaced.

In this embodiment, it is assumed that the first end of each ring segment in the clockwise direction is the first end, and the rear end is the second end (in other embodiments, the first end and the second end may also be set to each other. replace). Then, in addition to the first ring segment 41 having the largest and smallest radius, the second end of any one of the first ring segments 41, the first end of the first ring segment 41 having a slightly smaller radius opposite to the opening is connected Segment 51 is connected. The two first ring segments 41 having the smallest radius have their respective first ends similar to the other first ring segments 41, and their respective second ends are directly connected by the connecting segments 51.

The two first ring segments 41 having the largest radius have their respective second ends similar to the other first ring segments 41, and their respective first ends serve as the input and output ends of the RF current Irf, respectively. After the RF current Irf is applied to the coil 31 of the structure, the current flowing in any one of the first loop segments 41 is opposite to the current flowing in the first loop segment 41 in the same direction of the adjacent one opening.

In another embodiment, as shown in FIG. 4, the inductive coupling coil 32 includes a plurality of second ring segments 42 that are approximately one-quarter of a ring. The second ring segments 42 are divided into four groups, each of which has a plurality of second ring segments 42 having the same opening direction, decreasing in radius, and spaced apart in the radial direction (the dotted line portion in FIG. 4 is not the coil 32 actually The existing part is set to facilitate the division of the grouping of the ring segments). For convenience of description, it is referred to as a first group to a fourth group in a clockwise direction, that is, the second ring segments 42 of the first group and the third group are oppositely opened, and the second group and the second group are second. The ring segments 42 are open opposite. Also, any four of the four sets of contiguous second ring segments 42 are wrapped around a hypothetical ring but are not connected to each other.

In addition to the second ring segment 42 having the largest and smallest radius in each group, the second end of any one of the other second ring segments 42 in each of the groups is slightly smaller than the clockwise adjacent one. The first end of the second ring segment 42 is connected by a connecting segment 52.

In the first group and the second group, the second end of the second ring segment 42 having the smallest radius is directly connected by the connecting portion 52; and, in the third group and the fourth group, the second ring segment 42 having the smallest radius The two ends are also directly connected by another connecting section 52. The first end of the second ring segment 42 having the smallest radius among the groups is connected in a similar manner to the others.

The second ring segment 42 having the largest radius in the first group has a first end as an input end of the radio frequency current Irf; in the second group and the third group, a first end of the second ring segment 42 having the largest radius is connected; The first end of the second ring segment 42 having the largest radius in the group acts as the output of the RF current Irf. The second end of the second ring segment 42 having the largest radius among the groups is connected in a similar manner to the others. Therefore, after the RF current Irf is applied to the coil 32 of the structure, the direction of the current flowing in each of the second loop segments 42 in any one of the groups is opposite to the current flowing in a second loop segment 42 adjacent thereto.

In still another embodiment as shown in FIG. 5, the inductive coupling coil 33 is provided with six groups each comprising a plurality of third ring segments 43 which are approximately one-sixth of a ring. Then, in each of the two groups adjacent in the clockwise direction, the second end of the third ring segment 43 having the smallest radius is directly connected through the connecting portion 53. And, assuming that any one of the groups is the first group, the first end of the third ring segment 43 having the largest radius in the group is the input end of the radio frequency current Irf, and is in a group adjacent to the first group of counterclockwise directions. The first end of the third ring segment 43 having the largest radius is the output end of the radio frequency current Irf. Starting from the clockwise direction of the first group, the first end of the third ring segment 43 having the largest radius in each of the two adjacent groups is directly connected by the connecting portion 53. In addition to the above, the second end of any one of the other third ring segments 43 of each of the other groups is connected to the first end of the third ring segment 43 having a slightly smaller radius in a group adjacent to the clockwise direction. Segment 53 is connected. Therefore, a shot is applied to the coil 33 of the structure. After the frequency current Irf, each of the third ring segments 43 in any one set is opposite in direction to the current flowing in a third ring segment 43 adjacent thereto.

In some other embodiments, other even number of ring segment groups may also be used, for example, by setting eight sets of ring segments of approximately one-eighth ring, etc., to form the inductive coupling coil to satisfy each group. The current of any one of the ring segments is opposite to that of the one ring segment in the radial direction, and the connection manner of the ring segment group is similar to that of the above embodiments, and will not be described again.

As shown in FIG. 6 , and in conjunction with FIG. 1 , the present invention further provides an inductively coupled plasma processing apparatus including a reaction chamber 4 in which an electrostatic chuck 6 is disposed at a bottom portion of the reaction chamber 4 . The wafer 5 waiting to be processed is placed on the electrostatic chuck 6. The inductive coupling coil 31, 32, or 33 of any of the above structures of the present invention is disposed above the outer side of the top plate of the reaction chamber 4, and the side wall of the reaction chamber 4 is omitted in Fig. 6, showing only the top plate and the electrostatic chuck. Dielectric layer 20. The positions of the centers of the coil, the reaction chamber 4, the wafer 5, and the electrostatic chuck 6 correspond to each other.

Additionally, a first RF source 1 is coupled to the coil by a first matcher 2 for providing a radio frequency current Irf applied to the coil to provide RF power for generating plasma within the reaction chamber 4. The surface of the wafer 5 is etched or the like by plasma generated in the reaction chamber 4. At the same time, a second RF source 11 can be disposed to be connected to the electrostatic chuck 6 through the second matching device 10, and the bias voltage is supplied after the other RF power source is turned on to increase the collision of the plasma with the wafer 5. The energy of the ions.

Referring to FIG. 3 and FIG. 6, the arrow in FIG. 6 indicates the direction of the magnetic induction B, and the dip indicates the direction in which the RF current Irf flows out or flows into a certain ring segment; and in contrast to FIG. 6, the arrow in FIG. Refers to the direction of current, and the point of the mark is the direction of magnetic induction B, where the point indicates the direction perpendicular to the outward direction of the paper, and the cross indicates the direction perpendicular to the paper inward. It can be seen that in the inductive coupling coil (Fig. 3 to Fig. 5) of each of the above embodiments of the present invention, since the current flows in any two radially adjacent ring segments in opposite directions, directly above the two ring segments Strong magnetic field Some of the degrees cancel each other out, and the other part is superimposed to produce a vertical magnetic field.

For details, please refer to FIG. 7 , taking the leftmost two magnetic magnetic lines in FIG. 6 as an example. For the intersection Q of the adjacent magnetic lines of the two turns, the magnetic field strength directions are y1 and y2, respectively. Y1 has a component y1a and y1b in the horizontal direction and the vertical direction, respectively, and the same y2 has a component y2a and y2b in the horizontal direction and the vertical direction, respectively. Since the current directions for generating the two magnetic lines of inductance are opposite, the components y1a and y2a in the horizontal direction cancel each other, and the components y1b and y2b in the vertical direction are superimposed and enhanced, and in the whole A vertical downward magnetic field strength is generated. Other directions such as the magnetic induction lines adjacent to the rightmost two turns in FIG. 6 are opposite to those shown in FIG. 7, and therefore, the magnetic field strength components of the rightmost two magnetic magnetic lines in the horizontal direction cancel each other out. Produces a superimposed and enhanced magnetic field strength in a vertically upward direction.

Referring to FIG. 8, the straight line shows the relationship between the magnetic field strength of the inductive coupling coil of the present invention and the radial position of the coil, and the broken line is the magnetic field strength of the existing single-turn helical coil and the radial position of the coil. Relationship; where the origin O refers to the center of the coil, and the radial position is the distance of a position on the coil at the center of the circle.

It can be seen that although the RF power is the same as that of the existing single-turn helical coil, the magnetic field strength generated by using the inductive coupling coil of the present invention is reduced, but the present invention is different in the radial direction of the coil, for example, From the center position to the edge position, the magnetic field strength is more uniform, thus ensuring that the generated plasma is more evenly distributed over the wafer, thereby ensuring uniform processing at different locations on the wafer.

Although the present invention has been described in detail by the preferred embodiments thereof, it should be understood that the foregoing description should not be construed as limiting. Various modifications and alterations of the present invention will be apparent to those skilled in the art. For example, the pitch of each of the radially adjacent ring segments in the coil of the present invention may be set to be the same or different pitch from the center to the edge of the coil, for example, the center has a large radial spacing. The radial spacing of the edges is small to further adjust the magnetic field strength and plasma density at different locations. For example, in the above-described coil of the present invention, the input end and the output end of the radio frequency coil can be interchanged. For example, the connection of the ring segments in the coil of the present invention may be reversed, that is, the first end of each ring segment of any group is changed to a segment with a slightly smaller radius in the group adjacent to the counterclockwise direction. The second end of the connection. As another example, ring segments of the same radius in each group may not have the same arc length, and so on. Therefore, the scope of the invention should be defined by the appended claims.

31‧‧‧Inductive Coupling Coil

41‧‧‧First ring segment

51‧‧‧ Connection section

B‧‧‧Magnetic induction

Claims (11)

An inductive coupling coil for use in a plasma processing apparatus for generating an electromagnetic field by applying a radio frequency current to the coil, wherein the inductive coupling coil is a planar structure coil having a plurality of radially spaced apart coils The conductive ring segments, wherein the direction of the RF current flowing through any two of the radially adjacent ring segments is opposite. The inductive coupling coil of claim 1, wherein the coil is provided with N ring segment groups, and the N series is even; the ring segment group includes a plurality of the ring segments having the same opening direction and decreasing in radius; Each ring segment is a one-ninth ring. The inductive coupling coil of claim 2, wherein the second end of the ring segment having a first radius in each of the ring segment groups and the second ring radius in another adjacent ring segment group The first end of the ring segment is connected by a conductive connecting segment; the first radius is different from the second radius, and two of the first radius and the second radius are in each ring segment group The ring segments are arranged adjacent in the radial direction of the coil. The inductive coupling coil of claim 3, wherein the first radius or the second radius is the minimum radius of the coil, and the second end of the ring segment having the smallest radius of each of the two ring segment groups , not connected to the first end of the other ring segments, but directly connected to the second ends of the two ring segments by the connecting segment. The inductive coupling coil of claim 4, wherein the first radius or the second radius is the maximum radius of the coil, and the first end of the ring segment having the largest radius among the ring segments is not Connecting with the second end of the other ring segments; the first ends of the ring segments having the largest radius of each of the two ring segments are respectively used as the input end and the output end of the RF current of the coil; and, other In each of the two ring segment groups, the first end of the ring segment having the largest radius is by the connecting segment And connect directly. An inductive coupling coil for a plasma processing apparatus for generating an electromagnetic field by applying a radio frequency current to the coil, wherein the inductive coupling coil is a planar structure coil, the coil being provided with a plurality of semi-circular segments, each two The semi-circular segments have the same radius and opposite openings; the semi-circular segments are divided into two groups, and each of the semi-circular segments has the same opening direction, a decreasing radius, and is arranged at a radial interval; The first end of the semi-annular segment having the largest radius among the two groups, and the second end of the semi-annular segment having a first radius, other than the second end of the semi-annular segment having the smallest radius of the two groups a first end of the semi-annular segment having a second radius opposite to the other opening, connected by a connecting segment; the first radius being different from the second radius, and having the same in the same group The two semi-circular segments of the first radius and the second radius are disposed adjacent to each other in the radial direction of the coil; the half-ring segments of the two groups having the smallest radius are directly connected by the connecting portion; And the half ring segments with the largest radius in the two groups, each Respectively as an input end and an output terminal of the RF current, the current RF coil in the radial direction, any two adjacent ring segment flowing through the system is reversed. An inductively coupled plasma processing apparatus, wherein the plasma processing apparatus comprises a reaction chamber, an electrostatic chuck is disposed at a bottom of the reaction chamber, and an inductive coupling coil is disposed above an outer side of the top plate of the reaction chamber; The inductive coupling coil is provided with a plurality of electrically conductive ring segments arranged along the radial interval of the coil, wherein the direction of the radio frequency current flowing on any two of the radially adjacent ring segments is opposite; a first RF source is used Connecting a first matching device, providing a radio frequency current to the coil to generate an electromagnetic field, thereby ionizing a process gas introduced into the reaction chamber to form a plasma, and processing the wafer placed on the electrostatic chuck by the plasma . The inductively coupled plasma processing apparatus of claim 7, wherein the coil There are N ring segment groups, and N is evenly numbered; each ring segment group includes a plurality of ring segments having the same opening direction and decreasing in radius; each ring segment is a one-Nth ring. The inductively coupled plasma processing apparatus of claim 8, wherein the second end of the ring segment having the smallest radius among the ring segment groups, and the first end of the ring segment having the largest radius among the ring segment groups, a second end of the ring segment having a first radius, and a first end of the ring segment having a second radius in the adjacent ring segment group, each of the ring segment groups The connecting segments are connected; the first radius is different from the second radius, and the two ring segments having the first radius and the second radius in the ring segment group are in the radial direction of the coil Adjacent arrangement. The inductively coupled plasma processing apparatus of claim 9, wherein in the group of ring segments, the second end of the ring segment having the smallest radius of each of the two ring segment groups is directly connected by the connection segment In the ring segment group, the first ends of the ring segments having the largest radius of each of the two ring segment groups respectively serve as the input end and the output end of the RF current of the coil; and, each of the other two The first ends of the ring segments having the largest radius of each of the ring segments are directly connected by the connecting segments. An inductively coupled plasma processing apparatus, wherein the plasma processing apparatus comprises a reaction chamber, an electrostatic chuck is disposed at a bottom of the reaction chamber, and an inductive coupling coil is disposed above an outer side of the top plate of the reaction chamber; The first RF source generates an electromagnetic field by supplying a radio frequency current to the inductive coupling coil by connecting a first matching device, thereby ionizing a process gas introduced into the reaction chamber to form a plasma, and the plasma pair is placed on the plasma source The wafer on the electrostatic chuck is processed; the inductive coupling coil is a coil of a planar structure, the coil is provided with a plurality of semi-circular segments, and the radius of each of the two semi-circular segments is uniform and the openings are oppositely disposed; Half ring segment Divided into two groups, each of the semi-circular segments has the same opening direction, a decreasing radius, and is arranged at a radial interval; except for the first end of the semi-circular segment having the largest radius in the two groups, and in the two groups The second end of the semi-annular segment having a first radius, the second end of the semi-annular segment having a first radius, and the first half of the semi-annular segment having a second radius opposite the other opening Ends are connected by a connecting section; the first radius is different from the second radius, and two of the semi-ring segments having the first radius and the second radius in the same group are in the radial direction of the coil Adjacent setting; the semi-ring segments having the smallest radius among the two groups, the second ends of the two are directly connected by the connecting segment; and the half-ring segments with the largest radius of the two groups are respectively used as the first ends respectively For the input and output ends of the RF current, the direction of the RF current flowing on any two of the radially adjacent segments of the coil is reversed.