Electrically reconfigurable deposition masks

Embodiments described herein provide for electrically reconfigurable deposition masks. One embodiment is a deposition mask that includes a plurality of electrical elements. Each of the electrical elements has an opening between a top surface and a bottom surface that constricts based on an electrical signal. A plurality of top surfaces of the electrical elements defines a top surface of the mask, and a plurality of bottom surface of the electrical elements defines a bottom surface of the mask.

FIELD

This disclosure relates to the field of deposition masks for deposition manufacturing processes, such as Physical Vapor Deposition (PVD) processes and/or Chemical Vapor Deposition (CVD) processes.

BACKGROUND

PVD processes and CVD processes are used in the manufacture of micro and nano scale devices, such as integrated circuits. In PVD and CVD, structures are created by highly precise masks or templates. Various features are cut through the masks and the absence or presence of the features defines where deposition occurs on a substrate.

The masks are often quite thin (e.g., 10 nanometers to 30 micrometers). This makes it difficult to scale the masks to larger sizes without the risk of breaking and/or distorting the masks. Further, thermal expansion effects are multiplied as the masks increase in size, which increases the misplacement of the desired features onto the substrate. It is desirable to utilize larger masks to fabricate a larger number of devices simultaneously, because it reduces the per-device manufacturing costs.

SUMMARY

Embodiments described herein provide for electrically reconfigurable deposition masks. The masks include arrays of electrical elements that have openings through the elements that can be constricted and/or closed utilizing electrical signals. Using a reconfigurable mask, features to be deposited onto a substrate can be adjusted at will. For instance, the features on the mask can be adjusted to compensate for registration issues between the mask and the substrate, thermal expansion of the mask, etc.

One embodiment is a deposition mask that includes a plurality of electrical elements. Each of the electrical elements has an opening between a top surface and a bottom surface that is configured to constrict based on an electrical signal. A plurality of top surfaces of the electrical elements defines a top surface of the mask, and a plurality of bottom surfaces of the electrical elements defines a bottom surface of the masks.

Another embodiment is a method of operating an electrically reconfigurable deposition mask. The method comprises placing a deposition mask proximate to a substrate, where the mask includes a plurality of coplanar electrical elements. Each of the electrical elements has an opening between a top surface and a bottom surface that is configured to constrict based on an electrical signal. A plurality of top surfaces of the electrical elements defines a top surface of the mask, and a plurality of bottom surfaces of the electrical elements defines a bottom surface of the mask. The method further comprises applying the electrical signal to at least one electrical element to close the opening and to prevent a deposition material from passing through the opening. The method further comprises depositing material onto the substrate through openings in the mask.

Another embodiment is deposition mask that includes an array of coplanar piezoelectric devices that are organized into rows and columns. Each of the piezoelectric devices has a passage between a top surface and a bottom surface that is configured to close in response to an electrical signal received by the piezoelectric device. A plurality of top surfaces of the piezoelectric devices defines a top surface of the mask, and a plurality of bottom surfaces of the piezoelectric devices defines a bottom surface of the mask.

DESCRIPTION

FIG. 1illustrates a deposition mask102. Typically, mask102is laser cut or etched through and then aligned to a substrate103. Portions of mask102that have been cut or etched away allow material from a deposition process to traverse a passage104through mask102and strike substrate103(e.g., a silicon wafer in cases of integrated circuit fabrication), forming a deposition feature105. Although the mask102may be cleaned and re-used, mask102is fragile and easily damaged or broken. In addition, laser cutting or etching mask102is a permanent alteration to the configuration of mask102. Thus, if mistakes are made or changes are desired in the configuration of mask102, then mask102is discarded and a new mask is fabricated.

When mask102is large, thermal expansion may render mask102unusable during the fabrication process due to temperature changes. For instance, if the desired features on mask102have a registration tolerance to substrate103of a few microns, then features near the edges (e.g., deposition feature105) of mask102may be misaligned to substrate103as mask102expands. This may preclude the ability to use larger masks during fabrication, which limits the number of devices that may be simultaneously fabricated with mask102, thereby increasing the per-device fabrication cost. Further, when different masks are utilized during fabrication, it may be difficult to ensure that each mask is registered correctly to substrate103. This may result in registration problems between masks and substrate103, which may distort or smear the features deposited on substrate103.

FIG. 2is an electrically reconfigurable deposition mask202in an exemplary embodiment. In this embodiment, mask202is utilized for a deposition process. For instance, mask202may be utilized in a CVD process and/or a PVD process to fabricate integrated circuits. Mask202includes a passage204that traverses mask202from an exterior top surface207of mask202to an exterior bottom surface208of mask202. Passage204allows a deposition material (not shown) to strike a substrate203and form a deposition feature205. Portions of mask202that do not include passage204block the material from striking substrate203.

In the embodiments described herein, mask202is electrically reconfigurable. Various electrical signals may be applied to mask202, which modify electrical elements206that are used to form mask202. Only a few instances of electrical elements206are shown inFIG. 2for clarity. However, mask202may include any number of electrical elements206as a matter of design choice. For instance, mask202may be formed entirely from electrical elements206, may be formed partially from electrical elements206, etc. In this embodiment, electrical elements206include a passage or window that can be constricted or closed as desired utilizing electrical signals, thereby allowing for a control of where material for a deposition process is applied to substrate203.

For instance, passage204may be formed by allowing a subset of electrical elements206in mask202to remain open. Further, passage204may be moved relative to substrate203, as illustrated by the arrow along mask202inFIG. 2, by modifying which subset of electrical elements206present in mask202remains open. This alters a location of deposition feature205on substrate203, as illustrated by the arrow along substrate203inFIG. 2. Because mask202is electrically reconfigurable, the deposition features applied to substrate203can be adjusted as desired. For instance, deposition feature205may be made smaller, larger, of a different shape, of a different position, etcetera, without fabricating a new mask. This is performed by reconfiguring which of electrical elements206in mask202remain open, and which of electrical elements206in mask202remain closed. Further, because mask202is electrically reconfigurable, mask202may be reconfigured during different manufacturing steps (e.g., while depositing different layers of an integrated circuit) without re-registering mask202to substrate203. This reduces the possibility of registration errors between mask202and substrate203and improves fabrication processes that utilize reconfigurable deposition masks, such as mask202.

FIG. 3Ais an isometric view of electrical element206utilized to form mask202in an exemplary embodiment. In this view, electrical element206has an opening304that traverses through a block302of material. Using electrical signals, opening304may be shrunk, reduced, constricted, etcetera, as desired. Therefore, opening304may be fully open, partially open, closed, or may exist within any condition between fully open and fully closed by modifying electrical signals applied to electrical element206. In this view, opening304is substantially open.

Electrical element206inFIG. 3Ahas a top surface306that corresponds to top surface207of mask202. Further, electrical element206inFIG. 3Ahas a bottom surface308that corresponds to bottom surface208of mask202. Block302may be formed from any material that is able to change shape based on an electrical signal. For instance, block302may be formed from a piezoelectric material which expands or contracts when subjected to a current, thereby constricting or expanding opening304. Some examples of piezoelectric materials include barium titanate (BaTiO3), lead titanate (PbTiO3), lead zirconate titanate (Pb[ZrxTi1-x]O3 0≤x≤1), potassium niobate (KNbO3), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), sodium tungstate (Na2WO3), zinc oxide (ZnO), Ba2NaNb5O5,

Although electrical element206inFIG. 3Ahas been illustrated as being substantially rectangular in shape, one skilled in the art will recognize that the particular shape, orientation, and/or relative dimensions illustrated inFIG. 3Aare a matter of design choice. Further, opening304may be substantially rounded, square, an ellipse, or any other configuration as a matter of design choice.

FIG. 3Bis an isometric view of electrical element206ofFIG. 3Ain a closed state in an exemplary embodiment. In this embodiment, opening304through top surface306of block302tapers down to form a cone310that blocks a deposition material from passing through electrical element206. When electrical element206is closed in this embodiment (e.g., in response to the application of an electrical signal to electrical element206), cone310tapers from a larger opening along top surface306towards a smaller or completely closed opening along bottom surface308.

FIG. 3Cis an isometric view of electrical element206ofFIG. 3Ain a closed state in another exemplary embodiment. In this embodiment, top surface306of block302is substantially or completely closed, which blocks a deposition material from passing through electrical element206.

FIG. 4is a top view of electrical element206in an exemplary embodiment. In this embodiment, block302of material is surrounded by an insulator402along the sides of block302. Some examples of insulator402includes polyethylene, cross-linked polyethylene, PolyVinyl Chloride, ceramic, Kapton®, rubber-like polymers, oil impregnated paper, Teflon®, silicone, and modified ethylene tetrafluoroethylene (ETFE). However, one skilled in the art will recognize that other insulating materials may be utilized to form insulator402as a matter of design choice.

When mask202is fabricated from a plurality of electrical elements206, insulator402may be utilized to electrically isolate one instance of electrical element206in mask202from another, although other configurations may exist (e.g., entire rows of electrical elements206may share the same driving signal for controlling the constriction of opening304). When a current is applied to block302, the material used to form block302may swell or contract and cause opening304to reduce in diameter or expand in diameter, respectively. For instance, if block302is formed from a material that swells or expands in response to an application of current to electrical element206, then opening304may have a larger diameter when the current applied to block302is low, non-existent, or below some threshold value. In this case, the application of a current to block302(e.g., above some threshold value) causes the material in block302to swell, which constricts opening304. Opening304may be constricted sufficiently to block a deposition material from passing through opening304. For instance, opening304may be closed entirely or substantially. This prevents a deposition material from traversing through opening304and contacting substrate203(seeFIG. 2).

If, for instance, block302is formed from a material that shrinks or contracts in response to an application of current, then opening304may be present when the current applied to block302is high or above some threshold value. With little or no current applied to block302, opening304may be closed or substantially closed. In this case, the reduction of a current to block302(e.g., below some threshold value) causes the material in block302to shrink, which expands opening304. Opening304may be expanded sufficiently to allow a deposition material to pass through opening304. This allows a deposition material to traverse through opening304and contact substrate203(seeFIG. 2).

FIG. 5Ais an isometric view of an array of electrical elements206including transistor drivers504-507that are utilized to form mask202in an exemplary embodiment. In this embodiment, a mask current source502selectively provides current to electrical elements206-1to206-4based on select signals508-511. Electrical elements206share a common ground503, which is a return path for source502. However, other configurations of electrical elements206may exist. For example, electrical elements206may be common to source502, with each having a pull-down transistor coupled to ground503. In this embodiment, transistors504-507are illustrated as P-channel Field Effect Transistors (FETs), although other configurations are possible.

With select signals508-509and511low, FETs504-505and507are on. Source502provides current to each of electrical elements206-1,206-2, and206-4. When electrical elements206are fabricated with materials that swell in response to an applied current, passages204for each of elements206-1,206-2, and206-4are closed. This is illustrated inFIG. 5Aby a lack of deposition material being applied to substrate203directly under electrical elements206-1,206-2, and206-4. With select signal510high, FET506is off. Source502does not supply current to electrical element206-3, and opening304for electrical element206-3remains open. This is illustrated inFIG. 5Aby deposition material being applied to substrate203directly under electrical element206-3.

In some embodiments, mask202is formed utilizing an array of electrical elements206, each configured to be addressable independently or substantially independently. In these embodiments, individual electrical elements206may remain open or be closed at will, which provides reconfiguration capabilities for mask202. For instance, if it is desired to move a deposition feature512relative to an edge514of substrate203(e.g., to resolve a registration issue and/or a thermal expansion issue), then it is possible to selectively open a nearby electrical element (e.g., electrical element206-2) and to close electrical element206-3, with the result being that deposition feature512will move to the left inFIG. 5Arelative to edge514of substrate203. This provides a substantial improvement over mask102ofFIG. 1, which is permanently laser cut or etched.

FIG. 5Bis a top view of electrical elements206in a column516and row518configuration that are utilized to form an electrically reconfigurable deposition mask in an exemplary embodiment. In this embodiment, a plurality of electrical elements206are assembled in columns516and rows518to form mask202. Although electrical elements206are illustrated in a 7×7 configuration in this view, any number or configuration of electrical elements206may be utilized to form mask202. In this embodiment, electrical elements206are assembled within a frame520, which holds electrical elements206in place. However, in some embodiments, electrical elements206may be bonded together, stitched together, glued together, sonically welded together, etcetera, as a matter of design choice.

FIG. 6is a flow chart of a method600of utilizing mask202for a deposition process in an exemplary embodiment. The steps of method600will be described with respect to mask202and electrical element206ofFIGS. 2-5; although one skilled in the art will understand that method600may apply to other reconfigurable masks not shown. The steps of method600are not all inclusive and may include other steps not shown.

For a deposition process (e.g., a CVD or a PVD process), mask202is placed proximate to substrate203(see step602ofFIG. 6). Various portions of mask202are selectively opened utilizing one or more control signals (e.g., select signals508-511ofFIG. 5A) to form the desired deposition features (e.g., feature512) onto substrate203(see step604ofFIG. 6). For instance, electrical elements206-1,206-2, and206-4are closed, which prevents a deposition material from striking substrate203. Material is then deposited onto substrate203through openings304of electrical elements206(e.g., electrical element206-3) that are utilized to form mask202(see step606ofFIG. 6).

FIG. 7is a side view of an electrical element206utilized to form mask202during a fabrication process in an exemplary embodiment.FIG. 7and the following discussion describe just one possible process for fabricating electrical elements206, and one skilled in the art will recognize that other processes may exist.

In this embodiment, electrical element206may be formed by coating an optical fiber702with a piezoelectric material704. The fiber702may be silicon or plastic. Fiber702, now coated with piezoelectric material704, may then be coated with an insulator706. Fiber702, now coated with both piezoelectric material704and insulation706, is sliced into blocks. Fiber702is etched away, leaving an opening in the block. The result is electrical elements206illustrated inFIGS. 3-4. Electrical elements206may then be assembled into coplanar arrays that form mask202. Electrical connections may then be made to electrical elements206, now assembled into mask202(e.g., as illustrated inFIG. 5AandFIG. 5B).

Although specific embodiments were described herein, the scope is not limited to those specific embodiments. Rather, the scope is defined by the following claims and any equivalents thereof.