Non-lithographic method of patterning contacts for a photovoltaic device

A dielectric material layer is formed on a front surface of a photovoltaic device. A patterned PMMA-type-material-including layer is formed on the dielectric material layer, and the pattern is transferred into the top portion of the photovoltaic device to form trenches in which contact structures can be formed. In one embodiment, a blanket PMMA-type-material-including layer is deposited on the dielectric material layer, and is patterned by laser ablation that removes ablated portions of PMMA-type-material. The PMMA-type-material-including layer may also include a dye to enhance absorption of the laser beam. In another embodiment, a blanket PMMA-type-material-including layer may be deposited on the dielectric material layer and mechanically patterned to form channels therein. In yet another embodiment, a patterned PMMA-type-material-including layer is stamped on top of the dielectric material layer.

BACKGROUND

The present disclosure generally relates to methods of forming contacts to a photovoltaic device, and particularly to non-lithographic methods of forming contacts to a front surface of a photovoltaic device on which light impinges.

Many photovoltaic devices employ a semiconductor p-n junction to induce spatial asymmetry by which electron-hole pairs generated by photons are directed in different directions. Typically, one type of semiconductor material is present on one side of a photovoltaic device, and the opposite type of semiconductor material is present on the other side of the photovoltaic device. The p-type material can be present on the front side and the n-type material can be present on the back side, or vice versa.

Light that impinges onto a front surface of a photovoltaic device passes through the front surface and generates an electron-hole pair within the semiconductor material. An electrostatic field generated by the p-n junction causes the electrons generated by the light to move toward the n-type material, and the holes generated by the light to move toward the p-type material. Contacts are made to the front side and the back side of the photovoltaic device to collect the charge carriers, thereby providing electromotive force for the photovoltaic device.

Contacts to the back surface of a photovoltaic device do not need patterning because light does not need pass through the back surface. Thus, a conductive sheet is typically employed as a back side electrode. Contacts to the front surface of a photovoltaic device need to be made to maximize the transmission of light through the front surface. Thus, contacts to the front surface of a photovoltaic cell are patterned, typically as a conductive grid having a pattern of parallel lines that are tied at one side or at both sides of the grid.

While such a conductive grid can be patterned employing lithographic methods, such processing steps tend to be expensive and time consuming. Thus, inexpensive and fast processing methods for forming contact structures on a front surface of a photovoltaic device are desired.

BRIEF SUMMARY

A dielectric material layer is formed on a front surface of a photovoltaic device. A patterned PMMA-type-material-including layer is formed on the dielectric material layer, and the pattern is transferred into the top portion of the photovoltaic device to form trenches in which contact structures can be formed. In one embodiment, a blanket PMMA-type-material-including layer is deposited on the dielectric material layer, and is patterned by laser ablation that removes ablated portions of PMMA-type-material. The PMMA-type-material-including layer may also include a dye to enhance absorption of the laser beam. In another embodiment, a blanket PMMA-type-material-including layer may be deposited on the dielectric material layer and mechanically patterned to form channels therein. In yet another embodiment, a patterned PMMA-type-material-including layer can be achieved by screen printing, ink jet printing, etc.

According to an aspect of the present disclosure, a method of forming contact structures on a photovoltaic substrate is provided, which includes: forming a dielectric material layer on a photovoltaic substrate; forming a patterned PMMA-type-material-including layer on the dielectric material layer; transferring a pattern in the patterned PMMA-type-material-including layer through the dielectric material layer and into an upper portion of the photovoltaic substrate, wherein trenches having semiconductor surfaces are formed in the upper portion of the photovoltaic substrate; and forming contact structures in the trenches.

In one embodiment, the patterned PMMA-type-material-including layer can be formed by applying a blanket PMMA-type-material-including layer on the dielectric material layer; and ablating portions of the blanket PMMA-type-material-including layer with a laser beam. Remaining portions of the blanket PMMA-type-material-including layer after the ablation is the patterned PMMA-type-material-including layer.

In another embodiment, the patterned PMMA-type-material-including layer can be formed by: applying a blanket PMMA-type-material-including layer on the dielectric material layer; immersing a plurality of protruding portions of a mechanical scribing device into the blanket PMMA-type-material-including layer; and inducing a relative movement between the blanket PMMA-type-material-including layer and the plurality of protruding portions.

In yet another embodiment, the patterned PMMA-type-material-including layer can be formed by screen printing or ink jet printing.

DETAILED DESCRIPTION

As stated above, the present disclosure relates to non-lithographic methods of forming contacts to a front surface of a photovoltaic device on which light impinges, which are now described in detail with accompanying figures. It is noted that like reference numerals refer to like elements across different embodiments. The drawings are not necessarily drawn to scale.

As used herein, a “photovoltaic substrate” refers to a substrate including a p-n junction between a p-type semiconductor material and an n-type semiconductor material. A photovoltaic device, which generates electricity by exposure to infrared, visible, and/or ultraviolet radiation, can be manufactured on a photovoltaic substrate by providing electrical contacts to the p-type semiconductor material and electrical contacts to the n-type semiconductor material.

As used herein, a “composite form” refers to a derivative form of a material that is derived from an original material by pigmentation with at least one oxide including, but not limited to, silicon oxide, aluminum oxide, and iron oxide. The amount of the at least one oxide in a composite form may be greater than 0 percent in volume concentration and up to 50 percent in volume concentration.

As used herein, a “PMMA-type-material-including” element refers to any element that includes at least one PMMA-type-material.

Referring toFIG. 1, a photovoltaic substrate8includes a first conductivity type semiconductor layer10and a second conductivity type semiconductor layer20. The first conductivity type semiconductor layer10includes a semiconductor material of a first conductivity type, which can be p-type or n-type. The second conductivity type semiconductor layer20includes a semiconductor material of a second conductivity type, which is the opposite type of the first conductivity type. For example, if the first conductivity type is p-type, the second conductivity type is n-type, and vice versa.

The first conductivity type semiconductor layer10includes a semiconductor material and dopants of the first conductivity type. The semiconductor material can be silicon, germanium, a silicon germanium alloy, a silicon carbon alloy, a silicon germanium carbon alloy, a III-V compound semiconductor material, a II-VI compound semiconductor material, or any other semiconductor material known in the art. The second conductivity type semiconductor layer20includes a semiconductor material and dopants of the second conductivity type. The semiconductor material of the second conductivity type semiconductor layer20can be the same as, or different from, the semiconductor material of the first conductivity type semiconductor layer10. The semiconductor material of the first conductivity type semiconductor layer10and the second conductivity type semiconductor layer20can be independently single crystalline, polycrystalline, and/or amorphous.

The thickness of the first conductivity type semiconductor layer10can be from 0.5 micron to 300 microns, and typically from 1 micron to 30 microns, although lesser and greater thicknesses can also be employed. The thickness of the second conductivity type semiconductor layer20can be from 0.1 micron to 10 microns, and typically from 0.2 microns to 2 microns, although lesser and greater thicknesses can also be employed.

P-type dopants can be B, Ga, In, or a combination thereof, and n-type dopants can be P, As, Sb, or a combination thereof. Dopant concentration in the first conductivity type semiconductor layer10can be from 1.0×1014/cm3to 1.0×1021/cm3, and typically from 1.0×1016/cm3to 1.0×1018/cm3, although lesser and greater dopant concentrations can also be employed. Dopant concentration in the second conductivity type semiconductor layer20can be from 1.0×1017/cm3to 1.0×1021/cm3, and typically from 1.0×1018/cm3to 1.0×1020/cm3, although lesser and greater dopant concentrations can also be employed.

A back side semiconductor layer12can be optionally provided in the photovoltaic substrate8. The back side semiconductor layer12contacts the back side of the first conductivity type semiconductor layer10, and has a doping of the first conductivity type, i.e., includes dopants of the first conductivity type. If present, the back side semiconductor layer12has a dopant concentration greater than the dopant concentration of the first conductivity type semiconductor layer10. Dopant concentration in the back side semiconductor layer20can be from 1.0×1017/cm3to 1.0×1021/cm3, and typically from 1.0×1019/cm3to 5.0×1020/cm3, although lesser and greater dopant concentrations can also be employed. The thickness of the back side semiconductor layer12can be from 0.2 micron to 30 microns, and typically from 0.4 micron to 3 microns, although lesser and greater thicknesses can also be employed.

One of the first conductivity type semiconductor layer10and the second conductivity type semiconductor layer20is a p-doped semiconductor material layer including a p-type semiconductor material, and the other of the first conductivity type semiconductor layer10and the second conductivity type semiconductor layer20is an n-doped semiconductor material layer including an n-type semiconductor material. The photovoltaic substrate8includes a p-n junction at an interface between the first conductivity type semiconductor layer10and the second conductivity type semiconductor layer20.

Optionally, a conductive plate30can be formed on the back side surface of the photovoltaic substrate8. The back side surface is the exposed surface of the back side semiconductor layer12, if present, or the exposed surface of the back side of the first conductivity type layer10if a back side semiconductor layer is not present. The conductive plate provides an electrical contact to the semiconductor material on one side of the p-n junction, i.e., the semiconductor material of the first conductivity type semiconductor layer10and, if present, the back side semiconductor layer12.

While a stack of the back side semiconductor layer12, the first conductivity type semiconductor layer10, and the second conductivity type semiconductor layer20is illustrated herein as a photovoltaic substrate8, the method of the present disclosure can also be employed for any photovoltaic substrate including a p-n junction therein.

A dielectric material layer40is formed on the exposed surface of the second conductivity type semiconductor layer20. The dielectric material layer40contacts the second conductivity type semiconductor layer20, and is formed on the opposite side of the conductive plate30. The dielectric material layer40includes a dielectric material, which can be silicon dioxide, silicon nitride, silicon oxynitride, aluminum oxide, any other dielectric material that is optically transparent in the infrared, visible, and/or ultraviolet range, and combinations thereof.

The dielectric material layer40can be deposited, for example, by chemical vapor deposition (CVD), spin coating and optional baking, or a combination thereof. The thickness of the dielectric material layer40can be from 50 nm to 2,000 nm, and typically from 100 nm to 1,000 nm, although lesser and greater thicknesses can also be employed.

A blanket PMMA-type-material-including layer50L is formed on the top surface of the dielectric material layer40. The blanket PMMA-type-material-including layer50L can be deposited, for example, by spin coating. The thickness of the blanket PMMA-type-material-including layer50L can be from 0.5 micron to 10 microns, and typically from 2 microns to 4 microns, although lesser and greater thicknesses can also be employed. The blanket PMMA-type-material-including layer50L can be self-planarizing if spin-coated.

In one embodiment, the blanket PMMA-type-material-including layer50L consists essentially of one or more PMMA-type-material.

In another embodiment, the blanket PMMA-type-material-including layer50L includes one or more PMMA-type-material and at least one dye that can enhance absorption of light. The blanket PMMA-type-material-including layer50L may consist essentially of one or more PMMA-type-material and at least one dye. If a dye is included in the blanket PMMA-type-material-including layer50L, the dye has an absorption wavelength range around at least one wavelength in the infrared, visible, or ultraviolet wavelength range. The dye enhances the absorption of the laser beam to be subsequently employed to ablate portions of the PMMA-type-material-including layer50L. The dye can be added to at least one PMMA-type-material and mixed to form a solution including the dye and the at least one PMMA-type-material, which is subsequently applied to the top surface of the dielectric material layer40. After the solvent evaporates, the blanket PMMA-type-material-including layer50L can be formed.

In general, any dye that can be uniformly mixed with at least one PMMA-type-material without segregation and has at least one absorption wavelength near the wavelength of a laser beam to be subsequently employed for local ablation can be employed for the blanket PMMA-type-material-including layer50L. In a non-limiting embodiment, the blanket PMMA-type-material-including layer50L includes PMMA-type-material and a dye selected from pyerenemethanol and Sudan III. The at least one dye can be present in the blanket PMMA-type-material-including layer50L at a weight percentage between 0.1% to 10%, although lesser and greater weight percentages can also be employed. The balance of the blanket PMMA-type-material-including layer50L can be the PMMA-type-material material therein, i.e., the blanket PMMA-type-material-including layer50L can consist essentially of PMMA-type-material and the at least one dye.

Referring toFIG. 2, portions of the blanket PMMA-type-material-including layer50L are ablated by a laser beam. The laser beam impinging on the blanket PMMA-type-material-including layer50L forms openings59in the blanket PMMA-type-material-including layer50L. The remaining portions of the blanket PMMA-type-material-including layer50L after the ablation is the patterned PMMA-type-material-including layer50, which is located on the surface of the dielectric material layer40.

The laser beam can have a wavelength in the infrared, visible, or ultraviolet range, and typically has a wavelength from 150 nm to 1,200 nm. In one embodiment, the laser beam may have an ultraviolet wavelength less than 400 nm. For example, the laser employed to generate the laser beam may be an excimer laser having a wavelength between 150 nm and 400 nm. In another embodiment, the laser beam may have a visible wavelength between 400 nm and 800 nm. For example, the laser employed to generate the laser beam may be a YAG laser having a wavelength between 400 nm and 800 nm.

The ablation of portions of the blanket PMMA-type-material-including layer50L exposes a surface of the dielectric material layer40underneath each opening59within the patterned PMMA-type-material-including layer50. Multiple openings59can be formed in the patterned PMMA-type-material-including layer50. Further, the multiple openings59can be formed to isolate the patterned PMMA-type-material-including layer50into multiple PMMA-type-material-including portions that do not contact one another.

The openings59within the patterned PMMA-type-material-including layer50can be in the form of line trenches that are parallel to one another. The width of each opening59within the patterned PMMA-type-material-including layer50can be on the order of the size of the laser beam, and is from 0.5 micron to 30 microns, and typically from 1 micron to 10 microns, although lesser and greater widths can also be employed. The laser beam can be continuously applied along the lengthwise direction of the openings59so that the openings59form line trenches running in a lengthwise direction. The length of such line trenches can be from 10 microns to 1 cm, although lesser and greater lengths can also be employed. The spacing between such line trenches can be from 1 micron to 100 microns, although lesser and greater spacings can also be employed.

Referring toFIG. 3, the pattern in the patterned PMMA-type-material-including layer50is transferred into a dielectric material layer40by an etch, which can be a wet etch. For example, a buffered oxide etch (BOE) employing hydrofluoric acid (HF) and ammonium fluoride (NH4F) diluted in water. The ratio of ammonium fluoride to hydrofluoric acid can be about 9:1, and the concentration of the ammonium fluoride and hydrofluoric acid in water can be adjusted as known in the art. The etch time is selected so that the dielectric material layer40is etched through to expose surfaces of the second conductivity type semiconductor layer20. The wet etch can proceed employing the patterned PMMA-type-material-including layer50as an etch mask so that the pattern of the openings59in the patterned PMMA-type-material-including layer50is replicated in the dielectric material layer40after the etch.

Referring toFIG. 4, the pattern in the dielectric material layer40is transferred into the photovoltaic substrate8and through the p-n junction between the first conductivity type semiconductor layer10and the second conductivity type semiconductor layer20by an etch. The residual PMMA-type-material-including layer50can be removed selective to the dielectric material layer40prior to the etch, or may be consumed during the etch.

Trenches58are formed in an upper portion of the photovoltaic substrate8in a manner that replicates the original pattern in the patterned PMMA-type-material-including layer50with the modification that the vertical cross-sectional profile of the trenches58may have a variable width due to the undercut of the dielectric material layer40that is introduced during the wet etch. The trenches58formed in the upper portion of the photovoltaic substrate8have semiconductor surfaces, which include surfaces of the first conductivity type semiconductor layer10and surfaces of the second conductivity type semiconductor layer20.

In one embodiment, a wet etch is employed to remove surface portions of the photovoltaic substrate directly underneath the openings59(SeeFIG. 3) in the dielectric material layer40. The wet etch employs the dielectric material layer40as an etch mask. The wet etch can employ any chemistry that etches the semiconductor material of the first and second conductivity type semiconductor layers (10,20) selective to the material of the dielectric material layer40. For example, the wet etch can employ an alkaline hydroxide solution such as NaOH or KOH.

If an alkaline hydroxide solution or any other chemical that etches a semiconductor material anisotropically, i.e., at different etch rates depending on the crystallographic orientations of exposed semiconductor surfaces, is employed and if the semiconductor material of the first conductivity type semiconductor layer10and/or the semiconductor material of the second conductivity type semiconductor layer20are single crystalline, the wet etch may produce a set of faceted crystallographic semiconductor surfaces. For example, a V-shaped groove may be formed for each trench59. The width of each V-shaped groove can be greater than the width of the overlying opening in the dielectric material layer40due to the undercut that the wet etch introduces.

If the openings59in the dielectric material layer40are in the form of a line cavity, the trenches58can be in the form of line trenches. In one embodiment, the line trenches are parallel to one another and extend along the same horizontal direction, i.e., a horizontal direction perpendicular to the plane of the cross-section ofFIG. 4.

Referring toFIG. 5, sidewall portions of the trenches58in the photovoltaic substrate8are doped to form doped semiconductor portions22. The doped semiconductor portions22are doped with dopants of the second conductivity type, i.e., with dopants of the same conductivity type as the dopants in the second conductivity type semiconductor layer20, which contacts the dielectric material layer40. Specifically, semiconductor portions of the photovoltaic substrate8underneath exposed surfaces of the trenches48are doped with dopants of the second conductivity type. The dopants can be introduced into the exposed semiconductor portions by ion implantation, gas phase doping, outdiffusion of dopants from a doped silicate glass layer (such as arsenosilicate glass, borosilicate glass, or phosphosilicate glass), or a combination thereof. The lateral extent of the doped semiconductor portions22, as measured from a sidewall of a trench58to the most proximate interface between the first conductivity type semiconductor layer10and the doped semiconductor portion22, can be from 0.1 micron to 5 microns, and typically from 0.2 microns to 1 microns, although lesser and greater thicknesses can also be employed.

A continuous p-n junction exists between the first conductivity type semiconductor layer10and the set of the second conductivity type semiconductor layer20and the doped semiconductor portions22. Formation of the doped semiconductor portions22increases the area of the p-n junction compared with the area of the p-n junction present in the structure ofFIG. 1, thereby enhancing the efficiency of the photovoltaic device.

Referring toFIG. 6, front-side contact structures60are formed by depositing a metallic material. In one embodiment, the front-side contact structures60can include a reflowable solder material that can be deposited in the trenches58and reflowed to fill the trenches58. Suitable liner materials (not shown) such as TiN, TaN, or WN can be deposited in each trench58before depositing the solder material. Such liner materials are incorporated into the front-side contact structures60.

If the trenches58are line trenches, the front-side conductive structures60can be conductive lines that run parallel to one another. If the trenches58are V-shaped grooves, the conductive lines can have a vertical cross-sectional profile in which the conductive lines include, from bottom to top, a V-shaped lower portion in which a width increases with height up to the bottom surface of the dielectric material layer40, a middle portion located between the height of the top surface and the bottom surface of the dielectric material layer40and having a width that is lesser than the maximum width of the V-shaped lower portion, and an upper portion in which the conductive material forms a hemispherical shape. The front-side contact structures60thus fill the trenches58. A top portion of each front-side conductive structure60can protrude above the top surface of the dielectric material layer40.

Referring toFIG. 7, a variation of the first exemplary semiconductor structure can be derived from the first exemplary semiconductor structure ofFIG. 3by employing an anisotropic etch instead of a wet etch. The pattern in the dielectric material layer40is transferred into the photovoltaic substrate8and through the p-n junction between the first conductivity type semiconductor layer10and the second conductivity type semiconductor layer20by an anisotropic etch. Trenches58′ are formed in the upper portion of the photovoltaic substrate8by the anisotropic etch, which employs the dielectric material layer40as an etch mask. The residual PMMA-type-material-including layer50can be removed selective to the dielectric material layer40prior to the anisotropic etch, or may be consumed during the anisotropic etch.

Trenches58′ are formed in the upper portion of the photovoltaic substrate8in a manner that replicates the original pattern in the patterned PMMA-type-material-including layer50. The width of the trenches58′ can be the same as the width of the openings59in the dielectric material layer40. The trenches58′ formed in the upper portion of the photovoltaic substrate8have semiconductor surfaces, which include surfaces of the first conductivity type semiconductor layer10and surfaces of the second conductivity type semiconductor layer20.

The anisotropic etch can employ any chemistry that etches the semiconductor material of the first and second conductivity type semiconductor layers (10,20) selective to the material of the dielectric material layer40. For example, a reactive ion etch employing hydrofluorocarbons can be employed.

If the openings59in the dielectric material layer40are in the form of a line cavity, the trenches58′ can be in the form of line trenches. In one embodiment, the line trenches are parallel to one another and extend along the same horizontal direction, i.e., a horizontal direction perpendicular to the plane of the cross-section ofFIG. 7.

Referring toFIG. 8, the same processing steps ofFIGS. 5 and 6can be performed to form doped semiconductor portions22and front-side contact structures60′.

If the trenches58′ are line trenches, the front-side conductive structures60′ can be conductive lines that run parallel to one another. The conductive lines can have a vertical cross-sectional profile in which the conductive lines include, from bottom to top, a constant-width lower portion embedded in an upper portion of the photovoltaic substrate8and the dielectric material layer40and having a constant width, and an upper portion in which the conductive material forms a hemispherical shape. The front-side contact structures60′ thus fill the trenches58′. A top portion of each front-side conductive structure60′ can protrude above the top surface of the dielectric material layer40.

Referring toFIG. 9, the intensity of radiation absorbed in a PMMA-type-material layer consisting of PMMA-type-material is shown as a function of wavelength. The vertical axis represents the fraction of radiation absorbed in PMMA-type-material that does not include any dye in an arbitrary unit. If the blanket PMMA-type-material-including layer50L (SeeFIG. 1) consists essentially of PMMA-type-material, a laser beam having a wavelength less than 250 nm is needed to ablate selected portions of the blanket PMMA-type-material-including layer50L.

Referring toFIG. 10, the intensity of radiation absorbed in a layer including PMMA-type-material and pyerenemethanol as a dye at 1.5 weight percentage, 3.0 weight percentage, and 4.5 weight percentage, respectively, is shown as a function of wavelength. The molecular structure of pyerenemethanol is shown inFIG. 11. The vertical axis represents the fraction of radiation absorbed in the various mixtures of PMMA-type-material and pyerenemethanol as a dye in an arbitrary unit. Pyerenemethanol enhances absorption of a laser beam without significantly affecting the ablation properties of PMMA-type-material. Thus, the mixture of PMMA-type-material and pyerenemethanol can be ablated to form openings in the PMMA-type-material-including layer in the same manner as a PMMA-type-material layer. If the blanket PMMA-type-material-including layer50L (SeeFIG. 1) includes a mixture of at least one PMMA-type-material and pyerenemethanol, a laser beam having a wavelength between 250 nm and 360 nm can be employed to ablate selected portions of the blanket PMMA-type-material-including layer50L.

Additional dye materials can also be employed provided that the added dye material does not significantly affect the ablation properties of the at least one PMMA-type-material. Another such material is Sudan III, of which the molecular structure is shown inFIG. 12. Sudan III is a lysochrome (fat-soluble dye) diazo dye used for staining of triglycerides in frozen sections, and some protein bound lipids and lipoproteins on paraffin sections. It has the appearance of reddish brown crystals and a maximum absorption at 507 (304) nm. If the blanket PMMA-type-material-including layer50L (SeeFIG. 1) includes a mixture of PMMA-type-material and Sudan III, a laser beam having a wavelength between 450 nm and 550 nm can be employed to ablate selected portions of the blanket PMMA-type-material-including layer50L.

In general, the dye material to be mixed with PMMA-type-material in the blanket PMMA-type-material-including layer50L can be selected to match the wavelength of the laser beam to be used for ablating portions of the blanket PMMA-type-material-including layer. Absorption wavelength of the dye can be selected in the wavelength range from 150 nm to 1,200 nm, although lesser and greater absorption wavelengths can also be employed.

Referring toFIG. 13, a second exemplary structure according to a second embodiment of the present disclosure includes a mechanical scribing device100and the material stack ofFIG. 2. The second exemplary structure can be derived by providing the first exemplary structure ofFIG. 1employing the same methods as in the first embodiment. The blanket PMMA-type-material-including layer50L may include a dye, but a dye is in general not necessary for the second exemplary structure because laser ablation is not employed.

Mechanical scribing is employed instead of laser ablation in the second embodiment. The mechanical scribing device100includes a comb-like downward protruding structure having planar tips that are located on the same horizontal plane. The width of each downward protrusion in the mechanical scribing device100has a width, which is the target width for the openings59to be formed in the patterned PMMA-type-material-including layer50.

Once a blanket PMMA-type-material-including layer is applied on the dielectric material layer40, the downward protrusions in the mechanical scribing device100, i.e., a plurality of protruding portions of the mechanical scribing device100, are immersed into the blanket PMMA-type-material-including layer by a relative movement between the mechanical scribing device100and the first exemplary structure ofFIG. 1in the vertical direction, which is the direction represented by the arrow Z inFIG. 13. The plurality of protruding portions of the mechanical scribing device100may, or may not, touch the top surface of the dielectric material layer40.

A relative horizontal movement is induced between the blanket PMMA-type-material-including layer and the plurality of protruding portions of the mechanical scribing device100. For example, the first exemplary structure ofFIG. 1may remain stationary, and the mechanical scribing device100may move in one horizontal direction represented by the arrow A inFIG. 13. In this case, the lateral movement of the mechanical scribing device100can be provided by a scribing device actuator120. Alternatively, the mechanical scribing device100may remain stationary, and the first exemplary structure ofFIG. 1may move in the opposite horizontal direction represented by the arrow B inFIG. 13. In this case, the lateral movement of the first exemplary structure can be provided by a substrate movement actuator2that holds and moves the first exemplary structure. In some embodiments, both a scribing device actuator120and a substrate movement actuator2can be employed.

In one embodiment, the plurality of protruding portions of the mechanical scribing device100contact the top surface of the dielectric material layer40when immersed into the blanket PMMA-type-material-including layer and while moving relative to the dielectric material layer40. The relative movement exposes a surface of the dielectric material layer40underneath openings59within the patterned PMMA-type-material-including layer50.

In another embodiment, the plurality of protruding portions of the mechanical scribing device100may not contact the top surface of the dielectric material layer40when immersed into the blanket PMMA-type-material-including layer and while moving relative to the dielectric material layer40. In such an embodiment, an etch can be performed to removed a thin layer of PMMA-type-material between the bottom surfaces of the openings59in the patterned PMMA-type-material-including layer50so that a surface of the dielectric material layer40is exposed underneath openings59within the patterned PMMA-type-material-including layer50after the etch. The etch can be an isotropic etch or an anisotropic etch.

The processing steps ofFIGS. 3-6or the processing steps ofFIGS. 3,7, and8are performed in the same manner as in the first embodiment to form a structure shown inFIG. 6orFIG. 8.

Referring toFIG. 14, a third exemplary structure according to a third embodiment of the present disclosure includes a stamping device200, which is employed to form the first exemplary structure ofFIG. 2. Specifically, the photovoltaic substrate8, the conductive plate30, and the dielectric material layer40are formed as described above. However, a PMMA-type-material-including layer is not applied directly to the top surface of the dielectric material layer40at this point.

Instead, a stamping device including a handle230, a stamp back plate220, and a patterned stamping pad210is employed. The patterned stamping pad210can include multiple isolated surfaces separated by channels that are parallel among one another. The width of each channel corresponds to the width of an opening59to be subsequently formed in a structure that is the same as the first exemplary structure ofFIG. 2.

At least one PMMA-type-material is applied to the patterned surface of the stamping device200, i.e., to the surface of the patterned stamping pad210, for example, by immersing the surface of the patterned stamping pad210within the at least one PMMA-type-material. The at least one PMMA-type-material on the patterned stamping pad210is stamped onto the top surface of the dielectric material layer40employing the stamping device200, i.e., by moving the stamping device200in the direction of the arrow R inFIG. 14.

The material of the patterned stamping pad210and the material of the dielectric material layer40are selected such that upon stamping, the PMMA-type-material on the surface of the patterned stamping pad210is transferred onto the surface of the dielectric material layer40. Specifically, the patterned surface of the patterned stamping pad210has a material that has less adhesion to the PMMA-type-material than the top surface of the dielectric material layer10.FIG. 14illustrates the third exemplary structure after stamping, i.e., the transfer of the patterned PMMA-type-material-including layer50onto the top surface of the dielectric material layer40.

In general, the patterned PMMA-type-material-including layer50can be formed by screen printing or ink jet printing.

The processing steps ofFIGS. 3-6or the processing steps ofFIGS. 3,7, and8are performed in the same manner as in the first embodiment to form a structure shown inFIG. 6orFIG. 8.