Patent Description:
The present invention relates to technology field of ion beam etching, and especially relates to an ion source apparatus and a usage method thereof, and a vacuum treatment system.

In the current processes for manufacturing semiconductor devices, sensors, memory devices and the like, ion beam etching system (IBE) has been adopted in more and more processes. The operating principle of ion beam is that, under low-pressure, the gas is passed into the ion source and the plasma is generated, subsequently the ion beam is pulled out through the ion grid meshes, and the ion in the ion beam is neutralized by the neutralizer, and then the particle beam reaches the substrate surface, so as to achieve the purpose of etching.

With the decrease on the key size of the devices and the increase on the complexity of the devices, the requirements for the uniformity of the IBE etching process are becoming increasingly high. The process uniformity of the IBE is determined by the performance of its ion source. At present, a helical coil antenna on a discharge cavity is utilized to generate the inductively coupled plasma (ICP) by loading radio frequency (RF) power in the common structure of the ion source (with reference to <FIG>). The plasma is mainly distributed in the elliptic regions as illustrated in <FIG>. However, since ICP is mainly diffused due to low-pressure, the distribution of the plasma density of the ion beam pulled by a conventional large-aperture ion source and the ion density flux passing through the ion grid meshes permanently exhibit a convex state, which is the highest at the center of the ion source and decreases radially with increasing distance from the source center, resulting in the non-uniformity of the IBE etching process. Therefore, how to optimize the design on the discharge structure of the ion source so as to generate more uniform plasmas, and further form an ion source with a uniform ion density distribution is the key to solve the uniformity of the IBE etching process.

<CIT> discloses a charged particle source and an operation thereof. <CIT> discloses a method of processing a substrate using an ion beam and apparatus for performing the same. <CIT> discloses a low density high frequency process for a parallel-plate electrode plasma reactor having an inductive antenna.

Dependent claims refer to preferred embodiments.

Provided in the exemplary embodiments of the present invention is an ion source apparatus and a usage method thereof, and a vacuum treatment system. The changing of the plasma density in the discharge cavity is satisfied by regulating the different power distribution, thereby ensuring the uniformity of the ion beam etching process.

Provided in the embodiments of the present invention is an ion source apparatus, as defined in claim <NUM>. The ion source apparatus comprises a discharge cavity. A cylindrical central axis of the discharge cavity is a central axis of the ion source apparatus, and a wafer is arranged at a position on the central axis of the ion source apparatus where is relative to an open end of the discharge cavity. The ion source apparatus further comprises first discharge coils, second discharge coils, and at least two layers of ion grid meshes. In the first discharge coils, a closed end of the discharge cavity is a U-shape, the first discharge coils are sleeved on a cylindrical outer side wall of the discharge cavity, and a first plasma discharge region for plasma discharge is formed at a position inside the discharge cavity where is proximity to the cylindrical outer side wall. In the second discharge coils, the second discharge coils are arranged at a U-shaped protruding portion of the discharge cavity, and a second plasma discharge region for plasma discharge is formed at a position inside the discharge cavity where is proximity to the U-shaped protruding portion. The at least two layers of ion grid meshes are laid at the open end of the discharge cavity. Both the first discharge coils and the second discharge coils are connected to a power divider.

The ion source apparatus further includes third discharge coils that are coaxially arranged with the first discharge coils on an inner side wall of the U-shaped groove, and a third plasma discharge region used for plasma discharge is formed at a position inside the discharge cavity where is proximity to the inner side wall of the U-shaped groove. The third discharge coil is connected to the power divider.

The ion source apparatus further includes fourth discharge coils that are arranged on an inner bottom wall of the U-shaped groove, and a fourth plasma discharge region for plasma discharge is formed at a position inside the discharge cavity where is proximity to the inner bottom wall of the groove, the fourth discharge coil is connected to the power divider.

In one embodiment, the first discharge coils are sleeved on an outer side of the discharge cavity, and a first radial gap R1 is provided between the first discharge coil and a peripheral wall of the discharge cavity, where the first radial gap R1 ranges from <NUM> to <NUM>; and/or, a second axial gap L1 is provided between the second discharge coils and the protruding portion of the discharge cavity, where the second axial gap L1 ranges from <NUM> to <NUM>; and/or, a third radial gap R2 is provided between the third discharge coils and the groove inner side wall of the discharge cavity, where the third radial gap R2 ranges from <NUM> to <NUM>; and/or, a fourth axial gap L2 is provided between the fourth discharge coils and the groove inner bottom wall of the discharge cavity, where the fourth axial gap L2 ranges from <NUM> to <NUM>.

In one embodiment, the ion source apparatus includes a radio frequency matcher and an ion source master controller; the first discharge coil, the second discharge coil, the third discharge coil and the fourth discharge coil are simultaneously connected to the power divider; the power divider, the radio frequency matcher and the ion source master controller are sequentially connected.

In one embodiment, the ion source master controller is connected to a neutralizer after being in communication with a direct current power supply.

In one embodiment, the ion source apparatus includes an air inlet pipe which vertically passes through the groove inner bottom wall at a central position of the groove inner bottom wall of the closed end.

In one embodiment, a width of the U-shaped protruding portion at the closed end of the discharge cavity is defined as RP, a radius of the inner bottom wall of the U-shaped groove of the discharge cavity is defined as RU, where RU/RP ranges from <NUM>:<NUM> to <NUM>:<NUM>.

In one embodiment, the number of layers of the ion grid meshes ranges from <NUM> to <NUM>.

In one embodiment, a radius of the open end of the discharge cavity is defined as RC, and a size of the RC matches a size of the wafer.

In one embodiment, when the size of the wafer is about <NUM> (<NUM> inches), the size of the R cavity ranges from <NUM> to <NUM>; when the size of the wafer is about <NUM> (<NUM> inches), the size of the R cavity ranges from <NUM> to <NUM>; when the size of the wafer is about <NUM> (<NUM> inches), the size of the radius RC further ranges from <NUM> to <NUM>.

Provided in the embodiments of the present invention is a usage method based on the ion source apparatus, as defined in claim <NUM>. The method comprises as follows. In Step <NUM>, operating parameters for an initial ion source apparatus are set; in Step <NUM>, wafer samples are etched; in Step <NUM>, an uniformity of the etched wafer samples is measured; in Step <NUM>, when a measurement result satisfy preset requirements, a subsequent step is proceeded; when the measurement result does not satisfy the preset requirements, powers from the first discharge coils to the fourth discharge coils are redistributed, the operating parameters for the ion source apparatus are regulated, and then Step <NUM> is returned for re-processing; and in Step <NUM>, an entire process is terminated and an optimization of a subsequent set of parameters is proceeded.

In one embodiment, in Step <NUM>, powers from the first discharge coils to the fourth discharge coils of the ion source apparatus are redistributed. According to density levels of the first plasma discharge region, the second plasma discharge region, the third plasma discharge region and the fourth plasma discharge region obtained by measurement, the radio frequency powers of the four discharge regions are turned up or down to complete setting the parameters; the first plasma discharge region is formed in the discharge chamber by the first discharge coils, the second plasma discharge region is formed in the discharge chamber by the second discharge coils, the third plasma discharge region is formed in the discharge chamber by the third discharge coils, the fourth plasma discharge region is formed in the discharge chamber by the fourth discharge coils.

In one embodiment, the method for regulating the density level of the plasma discharge regions is specifically as follows. In the case where the plasma densities of the first plasma discharge region and the second plasma discharge region of the wafer samples are high when an etching result of the wafer samples is that a central etching rate is fast and an edge etching rate is slow, the radio frequency powers of the first discharge coils and the second discharge coils can be turned down to decrease the plasma densities of the first plasma discharge region and the second plasma discharge region, or, the radio frequency powers of the third discharge coils and the fourth discharge coils can be turned up to increase the plasma densities of the third plasma discharge region and the fourth plasma discharge region. The current entering the third discharge coils and the fourth discharge coils are inversed with the current entering the first discharge coils and the second discharge coils to decrease a plasma distribution in the third plasma discharge region and the fourth plasma discharge region.

Provided in the embodiments of the present invention is a vacuum treatment system, as defined in claim <NUM>. The system comprises the ion source apparatus according to any one of the above embodiments.

Through the above technical solutions, compared to the prior art, the embodiments in the present invention have the following beneficial effects.

The present invention is detailedly elucidated below in conjunction with the accompanying drawings and embodiments.

In <FIG> represents the discharge coils, <NUM> represents the discharge cavity, <NUM> and <NUM> represent the ion grid meshes; in <FIG>, <FIG> represents the first discharge coils, <NUM> represents the second discharge coils, <NUM> represents the third discharge coils, <NUM> represents the fourth discharge coils, <NUM> represents the discharge cavity, <NUM> represents the first ion grid mesh, <NUM> represents the second ion grid mesh, <NUM> represents the wafer, <NUM> represents the air inlet pipe, <NUM> represents the first direct current power supply, <NUM> represents the second direct current power supply, <NUM> represents the neutralizer, <NUM> represents the ion source master controller, <NUM> represents the radio frequency power supply, <NUM> represents the radio frequency matcher, <NUM> represents the power divider, <NUM> represents the first plasma discharge region, <NUM> represents the second plasma discharge region, <NUM> represents the third plasma discharge region, <NUM> represents the fourth plasma discharge region.

The embodiments provided in the present invention are further detailedly elucidated in conjunction with the accompanying drawings. In the descriptions of the present invention, it is to be understood that the terms indicate an orientation or positional relationship such as "left side", "right side", "upper part", "lower part" based on the orientation or positional relationship illustrated in the accompanying drawings, and are intended only to facilitate the descriptions of embodiments of present invention and to simplify the descriptions, rather than indicating or implying that the apparatus or elements referred to must have a specific orientation or be constructed and operated in a specific orientation. The "first", "second" and the like do not indicate the degree of importance of the component, and therefore cannot be construed as a limitation of the embodiments provided in the present invention.

<FIG> illustrates a common structure of the ion source mentioned in the background technology at present, where <NUM> represents the discharge coils, <NUM> represents the discharge cavity, <NUM> and <NUM> represent the ion grid meshes. This kind of structure can easily lead to the nonuniformity of the IBE etching process. In order to solve the problem of non-uniformity of the IBE etching process caused by the un-regulatable plasma density in the background technology, the present invention aims to provide an ion source apparatus that can regulate the density of plasma. The principle is to regulate the density of plasma in the discharge chamber by regulating different power distribution, so as to implement the uniform ion beam etching process.

<FIG> illustrates the structural schematic diagram of the entire ion source apparatus. The core of the ion source apparatus is the discharge cavity <NUM> with a U-shaped closed end, and the cylindrical central axis of the discharge cavity is the central axis of the entire apparatus. Wafer <NUM> is correspondingly arranged on the central axis, and wafer <NUM> is arranged relative to the open end of discharge cavity <NUM>. The air inlet pipe <NUM> passes vertically through the center of the U-shaped groove with a closed end, and the gas enters the discharge cavity <NUM> through air inlet pipe <NUM>. The U-shaped discharge cavity <NUM> in the embodiments of present invention may also be a concave-shaped discharge cavity <NUM> comprising a groove portion and a protruding portion.

The ion source apparatus further includes four sets of discharge coils, namely, the first discharge coils <NUM>, the second discharge coils <NUM>, the third discharge coils <NUM> and the fourth discharge coils <NUM>. The arrangement of the four sets of discharge coils are as illustrated in <FIG>. The first discharge coils <NUM> are sleeved on a cylindrical outer side wall of the discharge cavity <NUM>, the second discharge coils <NUM> are arranged at the U-shaped protruding portion of the discharge cavity <NUM>, the third discharge coils <NUM> is coaxially arranged on the inner side wall of the U-shaped groove with the first discharge coils <NUM>, and the fourth discharge coils <NUM> are arranged on the inner bottom wall of the U-shaped groove. Four regions for plasma discharge are formed in the discharge chamber <NUM> by the first discharge coils <NUM> to the fourth discharge coils <NUM>. It should be noted here that the first discharge coils <NUM> and the second discharge coils <NUM> are merely needed to be arranged on the discharge chamber <NUM>, however in order to achieve the optimal regulation effect, the third discharge coils <NUM> and the fourth discharge coils <NUM> are also arranged in the present invention, different power regulation distribution are implemented through a single use or a combination use.

Subsequently, the first discharge coils <NUM>, the second discharge coils <NUM>, the third discharge coils <NUM> and the fourth discharge coils <NUM> are simultaneously connected with the power divider <NUM>; the power divider <NUM>, the radio frequency matcher <NUM> and the ion source master controller <NUM> are sequentially connected. The radio frequency matcher <NUM> is configured to distribute power to the power divider <NUM> of the four sets of discharge coils. By combining different discharge regions, different radio frequency powers are loaded on different discharge coils to implement the change of plasma density at different positions along the radial direction from the central axis of discharge cavity <NUM>.

In the present invention, the insulation materials such as quartz and ceramics (such as alumina and zirconia) are preferred for the discharge chamber <NUM>, and the sizes of discharge cavity <NUM> are set to match wafers <NUM> of different sizes. In <FIG>, the radius of the open end of discharge cavity <NUM> is defined as RC, and the size of RC is matched with the size of wafers <NUM>.

When the size of wafer <NUM> is about <NUM> (<NUM> inches), the size range of RC can be selected from <NUM> to <NUM>, with a recommended size of <NUM> in the preferred embodiment. When the size of wafer <NUM> is about <NUM> (<NUM> inches), the size range of RC is selected from <NUM> to <NUM>, with a further recommended size range of <NUM> to <NUM> for optimal etching uniformity.

The ion source apparatus further comprises at least two layers of ion grid meshes which are arranged at the open end of discharge cavity <NUM>, and at least two layers of ion grid meshes are parallel in pairs and arranged vertically with the central axis of discharge cavity <NUM>, and each layer of the ion grid mesh is connected with a DC power supply. The ion grid meshes can be two or more layers, but not more than seven layers, excluding the necessary two layers, the remaining layers are designed to prevent the closest two layers near the open end of discharge cavity <NUM> from being contaminated, while also regulating the ion density distribution.

As illustrated in <FIG>, in a preferred embodiment of the present invention, two layers of the ion grid meshes are set, which are the first ion grid mesh <NUM> and the second ion grid mesh <NUM> respectively. Each layer of the ion grid meshes is connected to a DC power supply which are defined as the first current power supply <NUM> and the second DC power supply <NUM> respectively. The first current power supply <NUM> and the second DC power supply <NUM> provide the DC power supply that provides voltage to the ion grid meshes, and then are in communication with the ion source master controller <NUM> to implement the overall control for the ion source. A neutralizer <NUM> is further provided in <FIG>, which is connected to a DC power supply and, is configured to neutralize the charged ion beam pulled out by the ion source after start-up.

As illustrated in <FIG>, for the four sets of discharge coils, namely, the first discharge coils <NUM>, the second discharge coils <NUM>, the third discharge coils <NUM> and the fourth discharge coils <NUM>, the placement position limitation relative to the discharge cavity <NUM> is given. Specifically, the first discharge coils <NUM> are sleeved on the outer side of the discharge cavity <NUM>, and the first radial gap R1 is provided between the first discharge coils <NUM> and the peripheral wall of the discharge cavity <NUM>, where the distance of the first radial gap R1 ranges from <NUM> to <NUM>; the second axial gap L1 is provided between the second discharge coils <NUM> and the protruding portion of the discharge cavity <NUM>, where the distance of the second axial gap L1 ranges from <NUM> to <NUM>; the third radial gap R2 is provided between the third discharge coils <NUM> and the inner side wall of the groove of the discharge cavity <NUM>, where the distance of the third radial gap R2 ranges from <NUM> to <NUM>; the fourth axial gap L2 is provided between the fourth discharge coils <NUM> and the inner bottom wall of the groove of the discharge cavity <NUM>, where the distance of the fourth axial gap L2 range from <NUM> to <NUM>. The distance of the first radial gap R1, the second axial gap L1, the third radial gap R2 and the fourth axial gap L2 are limited to a certain range to avoid a significant attenuation of plasma density.

At the same time, the width of the U-shaped protruding portion of the discharge cavity <NUM> is defined as RP, the radius of the inner bottom wall of the U-shaped groove of the discharge cavity <NUM> is defined as RU, and the RU/RP ranges from <NUM>:<NUM> to <NUM>:<NUM>. Similarly, the proportional range for the sizes of RP and RU is set to give full play to the regulation effect of the discharge coils.

In the preferred embodiment of the present invention, during the operation, the power for generating the plasma in the discharge chamber <NUM> is provided by the radio frequency power supply <NUM> with a power range of <NUM> to <NUM> kW, and there are commonly three distribution methods when the power divider <NUM> is distributing.

The first distribution method is that two arbitrary sets of the discharge coils operate together for discharge, such as the first discharge coils <NUM> and the second discharge coils <NUM> can be selected to operate in combination, the first discharge coils <NUM> and the third discharge coils <NUM> can be selected to operate in combination, that is, the sub-combinations formed by two arbitrary combinations in the four sets of discharge coils satisfy the requirements. After selecting a set of discharge coils to operate in combination, the power distribution ratio is Ratio=<NUM>:<NUM> to <NUM>:<NUM>.

The second distribution method is to select merely one discharge coils to operate alone, that is, the power is not distributed, and all are loaded on a separate discharge coils, so the discharge coils merely need to select one from the first discharge coils <NUM> to the fourth discharge coils <NUM> to form a single coil subset.

The third distribution method is to select three arbitrary discharge coils to participate in the operation. At this time, firstly one discharge coils is selected from the set (the first discharge coils <NUM>, the second discharge coils <NUM>, the third discharge coils <NUM> and the fourth discharge coils <NUM>) and recorded as the coil priority. Then, the subset containing two discharge coils which are randomly selected from the remaining three discharge coils is selected and recorded as the coil subset. The power distribution is performed preferentially Ratio1=coil priority: coil subset=<NUM>:<NUM> to <NUM>:<NUM>; then the power distribution ratio between the two discharge coils in the coil subset is determined by Ratio2=<NUM>:<NUM> to <NUM>:<NUM>.

The fourth distribution method is that the four sets of discharge coils all participate in the operation, and at this time, the power distribution ratio is more complex, which will elaborate specifically herein. There are two preferred implementations, the first one is to split the set of discharge coils (the first discharge coils <NUM>, the second discharge coils <NUM>, the third discharge coils <NUM>, the fourth discharge coils <NUM>) into two subsets. Each subset contains two discharge coils, the discharge coils of each subset are short-circuited into a single discharge coil, which are recorded as coil subset I and coil subset II. The power distribution ratio of the two subsets of discharge coils is ratio subset=coil subset <NUM>: coil subset <NUM>= <NUM>:<NUM> to <NUM>:<NUM>. The second one is also to split the discharge coils into two subsets, each subset contains two discharge coils, and the power distribution of the two subsets is determined by the ratio subset=<NUM>:<NUM> to <NUM>:<NUM>. The power distribution of the two discharge coils in each subset is then determined by the ratio sub-coils=<NUM>:<NUM> to <NUM>:<NUM>. When the power distribution is relatively complicated, at least one set of RF power supply <NUM> is selected to be configured for the ion source apparatus, or an independent RF power supply <NUM> and RF divider is configured for each discharge coils, and the same function is implemented by setting the corresponding RF power for different RF power supplies <NUM> directly by referring to the power distribution ratio.

When the ion source apparatus is configured to operate in the entire IBE system, the final etching process results commonly have the following three situations. The uniformity profile results of the typical etching results of the three IBE systems are as illustrated in <FIG>. The etching result I as illustrated in <FIG> has a rapid etching rate in the center and a slow etching rate on the edge, which represents a high plasma density in the center (corresponding to the first plasma discharge region <NUM> and/or the second plasma discharge region <NUM> in <FIG>) and a low plasma density on the edge (corresponding to the third plasma discharge region and/or the fourth plasma discharge region in <FIG>). The etching result II as illustrated in <FIG> is an M-shaped result with a slow etching rate in the center and edge position and a rapid etching rate at the middle position, which represents a low plasma density in the center and edge position (corresponding to the first plasma discharge region and/or the fourth plasma discharge region in <FIG>) and a high plasma density at the middle position (corresponding to the second plasma discharge region and/or the third plasma discharge region in <FIG>). The etching result III as illustrated in <FIG> has a slow etching rate in the center and a rapid etching rate on the edge, which represents a low plasma density in the center (corresponding to the first plasma discharge region <NUM> and/or the second plasma discharge region <NUM> in <FIG>) and a high plasma density on the edge (corresponding to the third plasma discharge region and/or the fourth plasma discharge region in <FIG>). According to the etching results, the operating parameters of the power distribution plasma source are optimized to obtain the optimal etching uniformity.

Subsequently, by taking the etching result I as illustrated in <FIG> as an example, the plasma density in the first plasma discharge region <NUM> and/or the second plasma discharge region <NUM> need to be reduced to optimize the etching result, that is, the RF power connected to the first discharge coils <NUM> and/or the second discharge coils <NUM> need to be reduced; or, the plasma density of the third plasma discharge region <NUM> and/or the fourth plasma discharge region <NUM> are increased, while inverting the current entering the third discharge coils <NUM> and the fourth discharge coils <NUM> with the current entering the first discharge coils <NUM> and the second discharge coils <NUM>, which can offset the magnetic flux in the middle region, reduce the plasma distribution in the middle region, and minimize the influence of the first discharge coils <NUM> and the second discharge coils <NUM> on the etching depth in the middle region. As can be seen from <FIG>, the middle region herein is the third plasma discharge region <NUM> and the fourth plasma discharge region <NUM>, and then the etching uniformity can be regulated to a good development direction. In a similar way, when the etching result is the situation II as illustrated in <FIG> or the situation III as illustrated in <FIG>, the plasma density in the corresponding region needs to be regulated, the magnitude of RF power loaded on different discharge coils, the current reversal of different discharge coils, or the combination of short-circuiting different discharge coils, and the like, actually need to be correspondingly regulated.

The specific process of optimizing the operating parameters for the ion source apparatus needs to be combined with the process of etching technology to optimize and regulate within the entire parameter range. The specific parameter optimization process is as illustrated in <FIG>. Firstly, the initial ion source operating parameters are set, and then the etching process results are measured by etching wafer samples to observe the shape of the results profile. By different profiles, it can be determined whether the density of one of the four plasma discharge regions needs to be regulated high or low, or whether other operating parameters of the ion source apparatus need to be regulated, such as the voltage or current loaded on the ion grid meshes. Through this process, the uniformity of the etching process results under most conditions can satisfy the requirements, such as a high power etching, a low power etching, and a medium energy etching.

Through the exposition in the above implementations, it can be determined that the optimized discharge structure of the ion source apparatus involved in the present invention can produce a more uniform plasma, and further form an ion source with a uniform distribution of particle density, and eventually implement the uniformity of the IBE etching process.

Eventually, the present invention further provides a vacuum treatment system including the ion source apparatus, that is, the ion source apparatus can be installed in the vacuum treatment system.

It can be understood by those skilled in the art that, unless otherwise defined, all terms used herein (both technical and scientific terms) have the same meaning as would be generally understood by those skilled in the art to which the present invention belongs. It should also be understood that terms such as those defined in a generic dictionary should be understood to have a meaning consistent with the meaning in the context of the prior art and, unless defined as herein, will not be interpreted with idealized or overly formal meanings.

The meaning of "and/or" as used in the present invention refers to the situations where they exist separately or simultaneously.

Claim 1:
An ion source apparatus, comprising a discharge cavity (<NUM>), wherein a cylindrical central axis of the discharge cavity (<NUM>) is a central axis of the ion source apparatus, a wafer (<NUM>) is arranged at a position on the central axis of the ion source apparatus where is relative to an open end of the discharge cavity (<NUM>); the ion source apparatus further comprising: a power divider, first discharge coils (<NUM>), wherein a closed end of the discharge cavity (<NUM>) is a U-shape, the first discharge coils (<NUM>) are sleeved on a cylindrical outer side wall of the discharge cavity (<NUM>), and the first discharge coils (<NUM>) are configured to form a first plasma discharge region (<NUM>) for plasma discharge at a position inside the discharge cavity (<NUM>) proximate to the cylindrical outer side wall;
second discharge coils (<NUM>), arranged at a U-shaped protruding portion of the discharge cavity (<NUM>), wherein the second discharge coils (<NUM>) are configured to form a second plasma discharge region (<NUM>) for plasma discharge at a position inside the discharge cavity (<NUM>) proximate to the U-shaped protruding portion; and
at least two layers of ion grid meshes (<NUM>, <NUM>), laid at the open end of the discharge cavity (<NUM>); wherein both the first discharge coils (<NUM>) and the second discharge coils (<NUM>) are connected to the power divider,
wherein the ion source apparatus further includes third discharge coils (<NUM>) that are coaxially arranged with the first discharge coils (<NUM>) on an inner side wall of a U-shaped groove, and that are configured to form a third plasma discharge region (<NUM>) for plasma discharge at a position inside the discharge cavity (<NUM>) proximate to the inner side wall of the U-shaped groove;
wherein the third discharge coils (<NUM>) are connected to the power divider,
wherein the ion source apparatus further includes fourth discharge coils (<NUM>) that are arranged on an inner bottom wall of the U-shaped groove, and that are configured to form a fourth plasma discharge region (<NUM>) for plasma discharge at a position inside the discharge cavity (<NUM>) proximate to the inner bottom wall of the U-shaped groove,
wherein, the fourth discharge coils (<NUM>) are connected to the power divider.