Patent ID: 12211663

In the following detailed description, reference is made to the accompanying drawings which form part thereof and in which are shown, for illustrative purposes, specific embodiments in which the invention may be practiced. In this regard, directional terminology such as “top,” “bottom,” “front,” “back,” “frontwards,” “rearwards,” etc. is used with reference to the orientation of the figure(s) described. Since components of embodiments may be positioned in a number of different orientations, the directional terminology is for illustrative purposes and is not limiting in any way. It is understood that other embodiments may be used and structural or logical changes may be made without departing from the scope of protection of the present invention. It is understood that the features of the various exemplary embodiments described herein may be combined, unless otherwise specifically indicated. Therefore, the following detailed description is not to be construed in a limiting sense, and the scope of protection of the present invention is defined by the appended claims.

In the context of this description, the terms “connected,” “attached” as well as “coupled” are used to describe both a direct and an indirect connection, a direct or indirect connection as well as a direct or indirect coupling. In the figures, identical or similar elements are given identical reference signs where appropriate.

FIG.2AandFIG.2Bschematically illustrate a charge carrier generation source100according to various embodiments. The charge carrier generation source100may include a charge carrier generation device. The carrier generation device is configured to generate a carrier plasma in the carrier generation area120. The charge carrier plasma is illustrated inFIG.2AandFIG.2Bby means of the plasma boundary108.

Such a charge carrier generation source100is suitable, for example, for processing the surface of a substrate by means of a charge carrier beam. The charge carrier generation source100is configured, for example, to emit a charge carrier beam that impinges on a region (also referred to as an impingement region) of the surface of the substrate. The charge carrier generation source100is configured to process the surface of the substrate with a charge carrier beam, such as ablating a material of the substrate or depositing a material on the surface of the substrate. According to one embodiment, the charge carrier generation source100is an ion beam source and the charge carrier beam is, for example, a focusing ion beam having a Gaussian-shaped charge current distribution density. In this example, the ion beam is used to ablate a thin film from a substrate. The ion beam source may be configured as a wide beam ion beam source.

The carrier generation source100includes a carrier generation area120. The carrier generation area120is configured to provide charge carriers. Charge carriers are, for example, ions or electrons.

The charge carrier generation source100further comprises a first electrode106. The first electrode106is also referred to as a grid electrode106, a plasma electrode106, or a screen electrode106.

The grid electrode106includes an electrically conductive carrier. The carrier has a first side and a second side opposite the first side. The first side is directly adjacent to the carrier generation area120, such as the plasma boundary108.

The carrier includes a plurality of through-holes116. The through-holes116extend from the first side through the carrier to the second side. The through-holes116each have a first opening surface at the first side (illustrated inFIG.2Aby means of the diameter ds1), and the through-holes116each have a second opening surface at the second side (illustrated inFIG.2Aby means of the diameter ds2). The first opening surface is larger than the second opening surface.

The grid electrode116has a thickness ts. The grid electrode116is configured such that the diameter dsof the opening or the opening surface of the opening at the first side of the carrier is a function of the thickness tsof the carrier, where the thickness tsis a function of time t due to wearing (ds1=f(ts(t))), as illustrated inFIG.2B.

A second electrode104having through-holes114corresponding to through-holes116of the grid electrode106is disposed at a distance Ig from the grid electrode106. The distance le1, le2of the plasma boundary108to the second electrode104changes due to the wearing of the first electrode106(le1>le2and ds1>ds3). In other words, by decreasing the thickness tsof the first electrode due to wearing, the plasma boundary108shifts towards the second electrode104.

The second electrode104may be a second grid electrode104. The second grid electrode104may be spaced Ig from the second side of the first grid electrode106. The second grid electrode104may include one through-hole114or a plurality of through-holes114. The through-holes114of the second grid electrode104may be arranged relative to the through-holes116of the first grid electrode106such that carriers from the carrier generation area120pass through the through-holes116of the first grid electrode106and through the through-holes114of the second grid electrode104.

The through-holes are configured such that the change in the cross-sectional area of the through-hole in the carrier is configured such that when the thickness of the carrier decreases (illustratively a shift of the first side towards the second side) from the first side, there is an “independent” reduction in the opening surface of the through-hole at the first side of the carrier. Thus, a drift of the carrier extraction current may be compensated. If the through-holes are optimally designed for wearing, active control of the charge carrier extraction flow is no longer necessary. Alternatively, the control effort is reduced. Thus, a constant or substantially constant carrier current may be effectuated by reducing the opening surface on the first side of the carrier as the thickness tsof the carrier reduces over time.

The following relationships are to be taken into account:

Jmax=4·ε09⁢2·eM⁢Vt32le2(1)Imax=Jmax·π4⁢ds2(2)
with leas the distance of the second electrode to the plasma boundary, where Ig is given by the thickness tsof the first electrode and the distance between the first electrode and the second electrode, e as the charge of the electron, so the vacuum permittivity, Jmaxthe space charge-limited carrier current per through-hole, and dsthe diameter of the through-hole, Vtthe voltage at the grid electrode, and M the mass of the charge carrier.

For a cylindrical through-hole, the charge carrier current Jmaxwould increase with decreasing thickness tsof the first electrode, as illustrated in diagram310inFIG.3A.

However, in various embodiments, the through-holes116have a shape that tapers from the first side to the second side. In various embodiments, the through-holes116may have a conical shape. For example, the first opening surface and/or the second opening surface may have a circular shape or a substantially circular shape. For example, the through-hole may be configured to have, for example, such cross-sectional variation (ds(ts)) as to accurately or substantially accurately compensate for the wear-induced displacement of the charge carrier flow. The opening surface at the first side of the carrier of the grid electrode106is thus reduced by wearing-induced decreasing thickness ts, as illustrated in diagram320inFIG.3B. As a result, a constant or substantially constant current of charge carriers per opening may be set as the thickness of the first electrode106decreases, as illustrated in diagram330inFIG.3C.

In various embodiments, the charge carrier generation source100includes a control device. The control device is configured to form an electrical potential at the grid electrode106. The control device may be further configured to control a flow of charge carriers from the carrier generation area120through the through-holes.

The control device may be further configured to apply a first electrical potential to the first grid electrode106and to apply a second potential, different from the first, to the second grid electrode104.

The control device may be further configured to control the charge carrier beam. The control device may be configured to change, control, pause, abort, and/or readjust the parameters and characteristics of the charge carrier beam automatically or manually or with an appropriate combination. This may involve, for example, the position or the electrical operating currents for various components of the charge carrier generation source. Similarly, this control device may affect direct or indirect parameters of the charge carrier beam, such as characteristics of a beam neutralization device, composition and dose for output gases for the charge carrier generation source, and/or temperatures of various components. For example, an accelerating voltage may be changed, which affects the kinetic energy of the charged carriers in the charge carrier beam. The control device may further include and control or regulate a gas supply (not shown) or a plasma excitation (not shown) to the charge carrier generation source, such that the number of charge carriers in the charge carrier beam may be regulated. A gas supply may be generally required for carrier generation sources to maintain a carrier beam. Plasma excitation is generally required for charge carrier generation sources that are operated with charged charge carriers to generate the necessary charge carriers (e.g., ions) for a charged or non-neutral charge carrier beam from the supplied gas.

The control device may include a processor, computer, or other data processing device (hereinafter referred to as a process module computer PMC) that receives and evaluates the individual signals from the components and modules of the device and controls or regulates the same.

The PMC may be a freely programmable processor (for example, a microprocessor or a nanoprocessor), or hard-wired logic, or firmware, or for example, an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). Associated with the PMC is, among other things, an axis system that is connected to a carrier beam circuit and an acceleration circuit (also referred to as an accelerator circuit) by means of a switch circuit to control the beam source carrier beam and its beam profile. The charge carrier beam circuit and the accelerator circuit may each have a power supply, which may be basically technically identical to each other. The switch circuit may each have an electrically switchable switch, such as a power transistor, between the radiation source and the charge carrier beam circuit and/or between the radiation source and the accelerator circuit. The switch circuit may be configured such that the electrical potential of the charge carrier beam circuit and/or the accelerator circuit may be electrically connected to the radiation source, or alternatively, a ground potential or other electrical potential may be connected to the radiation source.

FIG.4illustrates a first electrode106of a charge carrier generation source100according to various embodiments. In various embodiments, the plurality of through-holes116may be a first plurality402of through-holes and the carrier may include at least a second plurality404,406,408,410of through-holes. The through-holes of the second plurality404,406,408,410may extend from the first side through the carrier to the second side. The through-holes of the second plurality404,406,408,410may each have a third opening surface at the first side and the through-holes404,406,408,410of the second plurality may have a fourth opening surface at the second side. The third opening surface may be larger than the fourth opening surface. The first opening surface may be different than the third opening surface and/or the second opening surface may be different than the fourth opening surface. The through-holes402of the first plurality and the through-holes404,406,408,410of the second plurality may be concentric with each other. In various embodiments, multiple pluralities of through-holes406,408,410may be provided. The pluralities have mutually different opening surfaces on the first side and the second side of the carrier of the first electrode106. Thus, a spatial wear profile of the first electrode106may be adjusted. For example, the first electrode may be configured to decrease in taper from the center of the first electrode to the edge, such as from (nearly) tapered through-hole(s)402at the center of the first electrode to (nearly) cylindrical through-hole(s)410at the edge of the first electrode, with differently shaped frustoconical through-holes404,406408laterally disposed therebetween. This enables position-independent constant charge carrier current (FIG.3C) to be set across the surface of the first electrode. For example, in case of position-dependent wearing of the electrode. As an example, the wearing of the first electrode106may be more pronounced in the center than at the edge of the first electrode106. This position-dependent wearing may be taken into account by means of position-dependent differently shaped through-holes.