Patent Application
20200135464
Embodiments of the present disclosure generally relate to substrate processing equipment, and more particularly, to methods and apparatus for performing physical vapor deposition (PVD).
The semiconductor processing industry generally continues to strive for increased uniformity of layers deposited on substrates. For example, with shrinking circuit sizes leading to higher integration of circuits per unit area of the substrate, increased uniformity is generally seen as desired, or required in some applications, to maintain satisfactory yields and reduce the cost of fabrication. Various technologies have been developed to deposit layers on substrates in a cost-effective and uniform manner, such as chemical vapor deposition (CVD) or physical vapor deposition (PVD).
However, the inventors have observed that with the drive to produce equipment to deposit more uniformly, certain applications may not be adequately served where purposeful deposition is required that is not symmetric or uniform with respect to the given structures being fabricated on a substrate. For example, the inventors have observed that asymmetric or non-uniform deposition of target material during a PVD process can advantageously be used to control the critical dimension of features formed on the underlying substrate.
Methods and apparatus for processing a substrate are provided herein. In some embodiments, a method for processing a substrate includes: directing a stream of material from a PVD source toward a surface of a substrate at a non-perpendicular angle to the plane of the surface to selectively deposit the material on a top portion of one or more features on the substrate and form an overhang extending beyond a first sidewall of the one or more features; and etching a first layer of the substrate beneath the one or more features selective to the deposited material.
In some embodiments, a method for processing a substrate includes: directing a stream of material from a PVD source toward a surface of a substrate at a non-perpendicular angle to the plane of the surface to selectively deposit the material on a top portion of one or more features on the substrate and form an overhang extending beyond a first sidewall of the one or more features; rotating the substrate; directing a stream of material from the PVD source toward a surface of a substrate at a different non-perpendicular angle to the plane of the surface to selectively deposit the material on the top portion of the one or more features on the substrate and form an overhang extending beyond at least one of a second sidewall and a third sidewall of the one or more features; and etching a first layer of the substrate beneath the one or more features selective to the deposited material.
In accordance with an aspect of the disclosure, there is provided a nontransitory computer readable storage medium having stored thereon a plurality of instructions that when executed cause a process controller to perform a method for processing a substrate. The method can include any of the embodiments disclosed herein. In some embodiments, the method includes: directing a stream of material from a PVD source toward a surface of a substrate at a non-perpendicular angle to the plane of the surface to selectively deposit the material on a top portion of one or more features on the substrate and form an overhang extending beyond a first sidewall of the one or more features; and etching a first layer of the substrate beneath the one or more features selective to the deposited material.
Other and further embodiments of the disclosure are described below.
Embodiments of the disclosure, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the disclosure depicted in the appended drawings, in which:
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
Methods and apparatuses for controlling critical dimension of an underlying substrate are disclosed herein. Embodiments of the disclosed methods and apparatus advantageously enable uniform angular deposition of materials on a substrate. In such applications, deposited materials are asymmetric or angular with respect to a given feature on a substrate, but can be relatively uniform within all features across the substrate. Furthermore, embodiments of the disclosed methods and apparatus advantageously can be used for one or more of the formation of selective etch hard masks, line edge roughness control for etch hard mask, pattern critical dimension (CD) control, tip-to-tip reduction, and profile modulation.
The PVD apparatus 100 is configured for the deposition of materials on a substrate 106 at a non-perpendicular angle to the generally planar surface of the substrate. The PVD apparatus 100 generally includes a first PVD source 102 and a substrate support 108 for supporting a substrate 106. The PVD apparatus 100 can also include one or more collimators 110.
The first PVD source 102 is configured to provide a first directed stream of material flux (e.g., a first stream 112) from the source toward the substrate support 108 (and any substrate 106 disposed on the substrate support 108). In some embodiments, the PVD apparatus 100 may include a second PVD source 104 configured to provide a second directed stream of material flux (e.g., a second stream 114) from the source toward the substrate support 108 (and any substrate 106 disposed on the substrate support 108). The substrate support has a support surface to support the substrate such that a working surface of the substrate to be deposited on is exposed to the first stream 112 of material flux and, when present, the second stream 114 of material flux. The first and second streams 112, 114 of material flux provided by the first and second PVD sources 102, 104 have a width greater than that of the substrate support 108 (and any substrate 106 disposed on the substrate support 108). The first and second streams 112, 114 of material flux have a linear elongate axis corresponding to the width of the first and second streams 112, 114 of material flux. The substrate support 108 is configured to move linearly with respect to the first and second PVD sources 102, 104, as indicated by arrows 116. Optionally, the substrate support 108 may additionally be configured to rotate about a z-axis of the substrate support 108 (i.e., a central axis perpendicular to the support surface) or tilt about a y-axis of the substrate support 108, as indicated by arrow 126. Deposition of materials at a non-perpendicular angle to the substrate surface can be used to advantageously create an overhang that extends beyond one or more sidewalls of a feature that is disposed on the substrate 106, as will be described in greater detail below.
The first and second PVD sources 102, 104 include target material to be sputter deposited on the substrate. In some embodiments, the target material of the first and second PVD sources 102, 104 are the same target material. Alternatively, in some embodiments, the respective target materials of the first and second PVD sources 102, 104 are different from each other. The target material can be, for example, a metal, such as titanium, or the like, suitable for depositing titanium (Ti) or titanium nitride (TiN) on the substrate. In some embodiments, the target material can be, for example, silicon, or a silicon-containing compound, suitable for depositing silicon (Si), silicon nitride (SiN), silicon oxynitride (SiON), or the like on the substrate. Other suitable materials may be used as well in accordance with the teachings provided herein. The first PVD source 102 further includes, or is coupled to, a power source to provide suitable power for forming a plasma proximate the target material and for sputtering atoms off the target material. The power source can be either or both of a DC or an RF power source.
Unlike an ion beam or other ion source, the first and second PVD sources 102, 104 are configured to provide mostly neutrals and few ions of the target material. As such, a plasma may be formed having a sufficiently low density to avoid ionizing too many of the sputtered atoms of target material. For example, for a 300 mm diameter wafer as the substrate, about 1 to about 20 kW of DC or RF power may be provided. The power or power density applied can be scaled for other size substrates. In addition, other parameters may be controlled to assist in providing mostly neutrals in the first and second streams 112, 114 of material flux. For example, the pressure may be controlled to be sufficiently low so that the mean free path is longer than the general dimensions of an opening of the first and second PVD sources 102, 104 through which the stream of material flux passes toward the substrate support 108 (as discussed in more detail below). In some embodiments, the pressure may be controlled to be about 0.5 to about 5 millitorr.
The lateral angles of incidence of the first and second streams of material flux can be controlled. For example,
In addition to the angles α 130 and β 132, within-plane angles at which the first stream 112 and the second stream 114 are directed toward the substrate 106 surface can also be used to create the overhang on the feature that is disposed on a substrate, as discussed in more detail below.
As discussed above, the apparatus can optionally include the collimator 110. The collimator 110 is a physical structure such as a shroud, disk, a plurality of baffles, or the like, having one or more openings 140, 142. When present, the collimator 110 is interposed between the first and second PVD sources 102, 104 and the substrate 106 such that the first and second streams 112, 114 of material flux travel through the collimator 110 to reach the substrate 106. Any materials with an angle to great to pass through the openings 140, 142 of the collimator 110 will be blocked, thus limiting the permitted angular range of materials reaching the surface of substrate 106. The collimator 110 may include a single opening. Alternatively/additionally the PVD apparatus 100 may include a single collimator 110 having multiple openings. The collimator can function as a spread angle control apparatus that controls the angle of the spread of materials being sputtered from the first and/or second PVD sources. The one or more collimators 110 can move linearly as shown by arrow 128.
The angle of incidence 130′, 132′ at which the first and second streams 112, 114 of material actually contact the substrate surface may be different than the angle of incidence 130, 132 at which the streams of material are provide by the first PVD source 102 and the second PVD source 104. The angle of incidence 130′, 132′ at which the first and second streams 112, 114 of material actually contact the substrate surface can be controlled/altered by one or more of the following: the angle of incidence 130, 132 at which the streams of material are provided by the first PVD source 102 and the second PVD source 104, the number and placement of openings in collimator 110, the linear position of collimator 110, and the rotation (e.g. arrow 126) of the substrate support 108 about the x-axis, y-axis, and/or z-axis.
The process controller 20 controls the overall operation of the PVD chamber 11. More particularly, the process controller 20 controls at least one or more of the first PVD source 102, the second PVD source 104 (when present), the substrate support 108, or the collimator 110 (when present). The process controller 20 can control movement of the substrate support 108, movement of the first PVD source 102 and movement of the second PVD source 104 for directing the first and second streams 112, 114 of material flux toward the substrate at one or more of the above-reference angles, and movement of the collimator 110, if used. The process controller 20 can also control a pressure inside the PVD apparatus 100 and an amount of power provided to a target material prior to, during and/or after PVD of the material onto the substrate 106.
The etching apparatus 30 can be configured to perform one or more suitable etching processes. For example, the etching apparatus 30 can be configured to perform a dry etching process and/or a wet etching process. The etching apparatus 30, for example, can be configured to perform a dry plasma etching process suitable for selectively etching materials as described in more detail below.
After an etching process of the substrate 106 is completed, removal of the deposited material may be necessary. Accordingly, one or more suitable target material removal apparatus 40 may be used to remove (e.g., strip away) the deposited material from the substrate 106. For example, the target material removal apparatus 40 can be a plasma etch chamber, which can be a component of the etching apparatus 30, but configured to etch material deposited on the substrate 106 using one or more gases that can be different from the gases used by the etching apparatus 30, or a separate stand-alone apparatus that can, for example, use dry O2 ashing or other suitable techniques to remove/strip the deposited material from the substrate 106.
The methods and embodiments disclosed herein advantageously enable deposition of materials with a shaped profile (e.g., creating an overhang) that may advantageously be used as an etch mask layer to control the shape of an underlying pattern to be etched into one or more layers of the substrate.
For example,
The layer B includes a top portion 312, on which the material 320 is deposited, and a bottom portion 314 that extends from the layer A (
The method for controlling critical dimension of the substrate 306, begins at 200 where a stream of material 320 from the first PVD source 102 is directed towards the substrate 306 surface at a non-perpendicular angle, e.g., a 130, a 132, or other suitable angle (see directional arrow F of
The material 320 is deposited on the top portion 312 of the layer B to form an overhang 316 that extends beyond the first and second sidewalls 301, 303 that define the feature 308. More particularly, the stream of material 320 is directed from the first PVD source 102, and the angle at which the stream of material 320 is directed allows for asymmetric deposition of the material 320 around the features 308. That is, the overhang 316 only extends beyond the first and second sidewalls 301, 303, but does not extend, or does not substantially extend, beyond the third and fourth sidewalls 305, 307 (compare
The collimator 110, which includes an opening, can be used to limit the angular range of the stream of material 320. More particularly, the placement of the collimator 110 (and physical structure of the collimator 110) with respect to the first PVD source 102 can be used to control the angle of incidence 130′ that the stream of the material 320 contacts the surface of the substrate 306, and, therefore can be used to control how far the overhang 316 extends beyond the first and second sidewalls 301, 303; however, as noted above, use of the collimator 110 is optional.
The substrate 306 can be scanned (e.g., linearly along arrow 116) through the stream of material 320 via the substrate support 108 to ensure that the material 320 forms an overhang 316 that extends beyond only the first and second sidewalls 301, 303 that define features 308, with minimal or no coverage on the first and second sidewalls 301, 303.
The amount/distance that the overhang 316 extends beyond the first and second sidewalls 301, 303 can depend on, but is not limited to, the material used for the PVD process, the angle at which the stream of material 320 is provided at, the angle of incidence 130′ that is controlled by the collimator 110, how many times the substrate support 108 is scanned, an angle at which the substrate support 108 is rotated, whether or not the second PVD source 104 is used in conjunction with the first PVD source 102, etc.
At 202, the substrate 306 is selectively etched using the etching apparatus 30, which as noted above, can be configured to perform a dry etching process, or other suitable etching process on the substrate 306. More particularly, and with reference to
While the above method has been described herein as including the first and second sidewalls 301, 303 with the overhang 316, the disclosure is not so limited.
For example,
An asymmetric PVD process is then performed in the manner as described above to deposit a layer of material 420 atop the layer of material B. As shown in
After the substrates 306, 406 have been etched, the material 320, 420 can be removed from the substrates 306, 406 using the target material removal apparatus 40, e.g., dry O2 ashing or other suitable process for selectively removing the material 320, 420.
In accordance with the disclosure, a critical dimension of the feature etched into layer A of the substrates 306, 406 can be achieved using the methods described herein.
The methods described herein can also be used for creating different etch patterns on a substrate. For example, one or multiple rows of vias can be formed on the substrate.
For example,
The substrate 506 and PVD process performed thereon, are similar to the previously described substrates and PVD processes, so only the features that are unique to
Unlike the previous described substrates, a plurality of individual features 508 extend from a layer B (see
Deposition of the material 520 between the third and fourth sidewalls 505, 507 can be achieved by adjusting, for example, an angle at which the stream of material 520 is deposited toward the substrate 506 and a direction at which the substrate support 108 is moved. For example, after forming the overhang 516 on the features 508, the substrate support 108 can be linearly scanned again, but prior to linearly scanning again, the angle at which the stream of material 520 is directed can be adjusted (e.g., changed to an angle that is different from the a 130, a 132) so that the material 520 is also deposited on the layer B between the third and fourth sidewalls 505, 507.
After the material 520 is deposited, the etching process is performed (
The substrate 806 includes the features 808 (e.g., similar to the features 508 of
After the overhangs 816 are formed on the features 808, the etching process is performed on the substrate 806, and the material 820 is removed (
The methods and apparatus described herein can advantageously be used for critical dimension reduction of a substrate, for reducing a distance between one or more of the various components that can be disposed on a substrate, and for creating various patterns on a substrate, in a more efficient manner than conventional methods and apparatuses that are configured to perform similar operations during substrate fabrication.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof.
