METHOD FOR MANUFACTURING SELECTIVE SURFACE DEPOSITION USING A PULSED RADIATION TREATMENT

Abstract

The present invention relates to a method of manufacturing a direct and selective surface deposition by a pulsed radiation treatment. Said method allows the production of a selective pattern on any receiving material without any pre-treatment and/or post-treatment of said receiving material. The invention provides a selective deposition of a monolayer donor material onto a receiving material by means of a pulsed radiation treatment without any contact between said donor and receiving materials. It further provides a method of direct surface metallization of various types of receiving materials using a pulsed radiation treatment. The present invention provides a method of manufacturing a direct and selective surface deposition by a pulsed radiation treatment of a monolayer donor material onto a receiving material. The present invention relates more particularly to a method of manufacturing free form patterned deposition on surfaces of various receiving materials.

Claims

1. A method of manufacturing a free form direct and selective surface deposition of a monolayer donor material onto a receiving material by a pulsed radiation treatment, the method comprising: a) selecting a monolayer donor material in a solid state, said donor material being made of only one material; b) selecting a receiving material able to receive a pulsed radiation treatment deposition, c) selecting an adapted pulsed radiation treatment that can both transfer the monolayer donor material onto the receiving material according to the chosen free form and in the meantime that can preserve the integrity of said receiving material, d) placing the monolayer donor material in a solid state on a spacer placed on the receiving material, without any contact between said donor and receiving material, e) applying the pulsed radiation of c) on the monolayer donor material in a solid state to transfer said monolayer donor material on the receiving material, said method being a free form one step deposition method with no pre-treatment and/or post-treatment of the donor or the receiving material.

2. Method according to claim 1, wherein the monolayer donor material has a thickness comprised between 1 m and 100 m and the implementation of the method allows the deposition of several microns thick layer on the donor material in a single step.

3. Method according to claim 1, wherein the pulsed radiation system is selected from a laser system or an electron beam system, said system displaying no shaping tools.

4. Method according to claim 1, wherein the monolayer donor material in a solid state is selected from a foil, a wire, a ribbon or a gel film.

5. Method according to claim 4, wherein the monolayer donor material is selected from a plastic and/or a polymer, a metal or a metal alloy, a biological material, a graphene or a silicon carbide sheet.

6. Method according to claim 5, wherein the monolayer donor material is a metal donor selected from a metal or a metal alloy.

7. Method according to claim 5, wherein the monolayer donor material is selected from plastic material or polymer material.

8. Method according to claim 1, wherein the receiving material has a planar or a three-dimensional surface to receive the donor deposition.

9. Method according to claim 1, wherein the receiving material is selected from a semi-conductor, plastic or polymer, textile, glass, paper, graphene and graphene related materials, ceramic, wood, acetate or Nafion.

10. Method according to claim 9, wherein the receiving material is selected from silicon, silicon related materials or silicon oxides.

11. Method according to claim 1, wherein the monolayer donor material, the spacer and the receiving material are held by a mechanical clamping system.

12. A method of manufacturing a free form direct and selective surface deposition of a metal monolayer donor material onto a receiving material by a pulsed radiation treatment, the method comprising: a) selecting a metal monolayer donor material in a solid state, b) selecting a receiving material able to receive a pulsed radiation treatment deposition, c) selecting an adapted pulsed radiation treatment that can both transfer the monolayer donor material onto the receiving material according to the chosen free form and in the meantime that can preserve the integrity of said receiving material, d) placing the metal donor material in a solid state on a spacer placed on the receiving material without any contact between said donor and receiving material e) applying the pulsed radiation on the donor material in a solid state to transfer the metal donor material on the receiving material surface; said method being a free form one step deposition method with no pre-treatment and/or post-treatment of the donor or the receiving material.

13. Method according to claim 12, wherein the pulsed radiation system is a laser system, said system displaying no shaping tools.

14. Method according to claim 12, wherein the metal monolayer donor material is selected from aluminium or aluminium alloys, bismuth or bismuth alloys, chromium or chromium alloys, cobalt or cobalt alloys, copper or copper alloys, gallium or gallium alloys, gold or gold alloys, indium, iron or iron alloys, lead or lead alloys, magnesium or magnesium alloys, mercury or mercury alloys, nickel or nickel alloys, potassium or potassium alloys, silver or silver alloys, sodium or sodium alloys, titanium or titanium alloys, tin or tin alloys, zinc or zinc alloys, zirconium or zirconium alloys, graphene or its related materials or silicone carbide or its related materials.

15. Method according to claim 12, wherein the receiving material is selected from semi-conductors, plastics or polymers, textiles, glasses, papers, graphene and graphene related materials, ceramics, acetates or Nafion.

Description

[0064] The above detailed figures are only illustrative of an embodiment of the present invention and are not to be interpreted as limitative.

[0065] An application of the method according to the invention is manufacturing plastic and/or polymers metallized circuit, so that a circuit structure can be formed on any plastic and/or polymer receiving material. Moreover a metal circuit layer of the desired circuit can be optionally formed on any one or more surfaces of the plastic and/or polymer receiving material to achieve patterned circuit arrangements, which can be applied to a variety of differently configured structures, such as antennas, light-emitting diode (LED) carriers, circuit boards, connectors, electronic devices, steering wheels and the like. Consequently the present invention is directed to a method of manufacturing a free form direct and selective surface deposition of a metal donor material onto a receiving material by a pulsed radiation treatment consisting of the following steps: [0066] a) selecting a metal donor material in a solid state, said donor material being made of only one material, [0067] b) selecting a plastic and/or polymer receiving material with a thickness down to 5 m and able to receive a pulsed radiation system treatment, [0068] c) selecting a pulsed radiation system able to transfer the metal donor material onto the receiving material surface according to the chosen free form and in the meantime that can preserve the integrity of said receiving material, [0069] d) placing the metal donor material in a solid state on a spacer placed on the receiving material without any contact between said donor and receiving material, [0070] e) applying the pulsed radiation of c) on the donor material in a solid state to transfer the metal donor material on the receiving material,

[0071] said method being a free form one step deposition method with no pre-treatment and/or post-treatment of the donor or the receiving material.

[0072] Another application of the method according to the invention is manufacturing smart textiles by creating metallic circuitries on textiles. In this particular embodiment the receiving material is a textile that will not be damaged by the pulsed radiation treatment (e.g. polyaramide or polyamide) during the deposition of the donor material. Consequently the present invention is directed to a method of manufacturing a free form direct and selective surface deposition of a metal donor material onto a textile receiving material by a pulsed radiation treatment consisting of the following steps: [0073] a) selecting a metal donor material in a solid state, said donor material being made of only one material, [0074] b) selecting a textile receiving material with a thickness down to 5 m, [0075] c) selecting a pulsed radiation system able to transfer the metal donor material onto the textile surface according to the chosen free form and in the meantime that can preserve the integrity of said receiving textile, [0076] d) placing the metal donor material in a solid state on a spacer placed on the textile without any contact between said donor and textile material, [0077] e) applying the pulsed radiation of c) on the donor material in a solid state to transfer the metal donor material on the textile,

[0078] said method being a free form one step deposition method with no pre-treatment and/or post-treatment of the donor or the receiving material.

[0079] A suitable textile according to the above-mentioned embodiment is typically cotton or any cotton mixture, whool or any whool mixture, synthetic textile or any synthetic textile mixture, neoprene, or pretreated material such as Gore-Tex.

[0080] Another application of the method according to the invention is manufacturing sensors. In this particular embodiment the receiving material is of any type and the process is a metallization process meaning that the donor material is a metal or a metal alloy. In the particular case of chips sensors the metallization process according to the invention can provide electrodes, circuits and contacts. The receiving materials are then selected from silicon, silicon oxides, semi-conductors like AsGa or others in III-V band, graphene, graphene related materials. The donor materials are selected from metals like aluminium, gold or any other suitable electrically conductive material.

[0081] Another application of the method according to the invention is the bio-printing of biological material. In this particular embodiment the receiving material is a biological material that will not be damaged by the pulsed radiation treatment during the deposition of the donor material. The donor material can be DNA or a protein foil as examples. In the case of implementation of the process according to the present invention to direct bio-printing of biological materials on biological substrates or non biological substrates, the manufactured devices can be biosensors devices, tissues engineering devices, regenerative tissues patches or DNA -arrays. In this case the receiving material is typically selected from paper sheet, glass, biological material films, flexible patches, petri dish, and the donor material is typically selected from DNA, skin cells, stem cells, proteins, tissues, etc.

[0082] The present invention is directed to a method of manufacturing a free form direct and selective surface deposition of a biological donor material onto a biological receiving material by a pulsed radiation treatment consisting of the following steps: [0083] a) selecting a monolayer donor material in a solid state, said donor material being made of only one material, [0084] b) selecting a biological receiving material with a thickness down to 5 m, [0085] c) placing the donor material in a solid state on a spacer placed on the receiving material, [0086] d) providing a pulsed radiation system able to transfer the donor material onto the receiving substrate material surface without any contact between said donor and receiving material, [0087] e) applying the pulsed radiation of d) on the donor material in a solid state to transfer the metal donor material on the receiving material,

[0088] said method being a free form one step deposition method with no pre-treatment and/or post-treatment of the donor or the receiving material.

[0089] The implementation of this particular embodiment of the invention can provide for biosensors devices, regenerative tissue patches, DNA -arrays, etc.

[0090] Others applications of the present invention in the field of epoxy glass metallization by cupper for manufacturing glass interposer, in the field of metal-coated glass fibers and flakes production by the metallization of glass fiber and also in the field of metallization of optical fibers by a thin layer deposition of metal for bonding and soldering of said optical fiber.

[0091] The invention will now be described in more details by referring to the following non-limiting example.

Example 1

Method of Manufacturing Selective Surface Metallization of Silicon Wafers by Laser Assisted Deposition

[0092] The present example illustrates the method according to the present invention where the donor material (3) is aluminium and the receiving material (4) is silicon. The field of implementation of the invention is the photovoltaic solar cell manufacturing.

[0093] The problem to be solved in this particular field is the selective or whole plate metallization of silicon wafers surface in the field of photovoltaic solar cell manufacturing. Indeed, there are many processes to deposit metal onto silicon wafer such as screen-printing with aluminium pastes or inkjet structured with evaporated aluminium metallization (Mingirulli, N., PROC. 34.sup.th IEEE PVSC 1064-1068, 2009Fallisch, A., PROC. 35.sup.th IEEE PVSC, 3125-3130, 2010Mattle, T. et al., Appl. Surf. Sci. 258, p. 9352-9354, 2012). All these methods are neither direct nor simple to be set up. They are time and material consuming.

[0094] Here below are detailed the results of direct laser printing of Al electrically conductive free shape patterns on thin mono and poly-crystalline silicon wafers (140 and 200 m thick). The patterns created are lines, crosses and squares. We measured and compared the electrical performances (Rsheet, Conductivity, Resistivity, Mobility . . . ) and mechanical properties (adhesion forces and volumes deposited) of this technique considering that we used different power densities, and different scan speeds. Scanning Electron Microscopy (SEM) pictures are taken for each case and it was demonstrated that the vicinities of the deposited metal are not thermally affected nor damaged. Combined with the Alicona 3D InfiniteFocus images, they revealed that the deposited areas dimensions can be: thick from 300 nm up to about 10 m, large from 100 m up to 22 cm.sup.2. The SEM's EDX module confirmed that the sheet deposited are over 93% in weight composed by aluminium: there is neither alloy nor oxide formed during the process. Standard scotch adhesion tests (3M Scotch-Weld Acrylic Adhesive 825) are successful. The Peel Strength at 22 C is 20 lb/inch (i.e. 350 g/mm). The first basic electrical tests, conductivities and Rsheet measurements, showed that the pattern can be used to conduct current: Rsheet are from 0.05 /sq to 0.15 /sq on all substrates (mono and poly crystalline silicon). Since this technique is maskless, operative in Normal Temperature and Pressure Conditions (NTPC) and cost effective, it can stand for a good alternative to classical metallization techniques.

[0095] A. Raw Material and Experimental Work

[0096] Silicon Wafers

[0097] As raw material, we used two main kinds of silicon wafers: poly-crystalline and mono crystalline from Cz growth method. The thicknesses that revealed not to be a major issue in the process were of 140 and 200 m. Since the results in scope of our experimentation do not depend on the wafers thickness, we will only present the results obtained on 200 m thick wafers.

[0098] Laser and Set-Up

[0099] The forward transfer of the donor onto the wafer's surface by programming and implement the laser sequence (Mattle, T. et al., Appl. Surf. Sci. 258, p. 9352-9354, 2012.

[0100] For these experimentations we used an infrared-pulsed laser source. The wafers were placed in free atmosphere. The distance between the donor and the substrate has to be controlled since this can lead to optimizations to obtain the best metallization while avoiding the spreading of the pattern one wants to produce in that laser direct transfer process. Indeed controlling that distance helps to mitigate the effects of acoustic (Mattle, T. et al., Appl. Surf. Sci. 258, p. 9352-9354, 2012) wave generated in the small volume formed between the donor and the substrate. This stands for the major point in that method as the full and tight contact between the foil and the silicon in the method developed by Nedarka et al. is mandatory. At this time, this method (Nedarka, J-F., PROC. 25.sup.th EPSE Conference, 2010Nedarka, J-F., PROC. Manufacturing Issues and Processing; 28th EPVSEC 2013) doesn't seem to be useful for selective application and micro machining.

[0101] Experimental Key Parameters

TABLE-US-00001 TABLE 1 Key parameters description and their impact on the process Parameter Parameter's type Range Pressure Environmental Atmospheric Temperature Environmental Ambient Spacer thickness Environmental 15 to 100 m Scan speed Environmental 20-100 mm/s Pulse overlap Laser 75 to 95% Wavelength Laser IR range Pulse shape & diameter Laser Gaussian Power Laser 0.7 to 4.5 W

[0102] The following morphological and mechanical parameters have to be controlled: deposited surface & deposited thickness, line width and spaces between lines, laser impact threshold and heat affected zone and also adhesion.

[0103] The following morphological and mechanical parameters have to be controlled: metallic link or bound (transversal cut) and chemical composition.

[0104] The following electrical parameters have to be controlled: Rsheet, conductivity, charge mobility, resistivity.

[0105] Patterns

[0106] We made different types of deposition on all the samples: lines, squares and crosses and free shape. These can serve as first point to identify all the possibilities offered by this method.

[0107] Operating Conditions (FIG. 1)

[0108] The process is based on the direct transfer of a metallic compounds onto a wafer. The basic phenomenon to be considered is linked with the heat dynamic. Heat dynamic can be related to the power, the overlapping rate, the space between the donor and the wafer and the scan speed. To simplify the operations we decided to keep constant some parameters values such as the scan speed, the frequency and the space between the donor and the silicon wafer. Said process is represented on FIG. 1.

[0109] All the following values come from measurements on the square pattern. These 11cm.sup.2 surfaces are the ideal surface to provide for electrical and mechanical parameters values. We used the same laser each time and covered a wide range of laser power values at the same overlap rate of 70%. The scan speed was kept equal to 50 mm/s

[0110] B. Results

[0111] 1) Electrical Measurement

[0112] The main goal of these experimentations and choice of a new method is to implement a way to metallize silicon wafers simply that can provide patterns for good electrical behavior. We come out to the point that in the field of the power tested from 0.75 to 5 W, all sample (squared one) were electrically conductive by the mean of a simple multimeter.

[0113] Rsheet Measurements (FIG. 2)

[0114] To go further, we also measured the Rsheet of all poly and mono crystalline square samples vs. the power used. To do so, we used a four points probes tool. Results are represented on FIG. 2 that shows Rsheet values versus power measured on square shaped metallized mono-crystalline Si wafer for an overlap rate of 70%.

[0115] What is noticeable is the very low value measured (minimum=0.05 /sq). The window from 1.8 to 4.5 W provides for repeatable low Rsheet values: very low resistant patterns that can be used for solar cells were produced.

[0116] Conductivity Measurements (FIG. 3)

[0117] We deposited Al on poly crystalline silicon wafers with different dopings and texturations. The results are represented on FIG. 3 that shows Rsheet values versus power (W) measured on square shaped metallized poly-crystalline Si wafer.

[0118] All the Rsheet measured exhibit the same behaviour: there is a threshold value of power (2 W) after which the Rsheet values are decreasing to attain the values observed on the monocrystalline wafers.

[0119] Hall Effect Values

[0120] Hall effects measurements were done on mono and poly crystalline samples with the same conditions to access the following measurements considering that the thickness of the Al coating is 10 m. Results are presented in Table 2 below.

[0121] Metallization on mono-Si seems to be more conducive than on poly crystalline wafer but with less mobility.

TABLE-US-00002 TABLE 2 Hall effect parameters on square shaped Al transferred on poly and mono silicon wafer Mean values Mon crystalline Poly Crystalline Conductivity (1/ .Math. cm) 1.4E04 2.07E3 Mobility (cm.sup.2/Vs) 3.33 6.38 Resistivity ( .Math. cm) 7.11E05 4.38E05

[0122] 2) Chemical and Metallurgical Topography

[0123] Chemical Composition

[0124] We made several SEM-HDX analyses in the different configuration we had, all of them showed that when the transfer is good in term of aspect, the amount weight of Al is huge. We found out that the minimum percentage in weight of Al in the composition of the deposited material is of 93% with traces of oxygen and carbone.

[0125] The results are represented on FIG. 4 that shows the EDX composition on square aluminium (Al) transferred on mono silicon wafer and pictures of that square and SEM details. When there, is a change in the overlapping rate from 70 to 85% by only changing the frequency, a narrow window where we can observe a black transferred material appeared. It may be due to structures that diffract light and enable alloys formation. As described in Urrejola, E., PROC. 2nd Workshop on Metallization, 2010 and in FIG. 5, both are probably right. This may be explained by the phase diagram of the AlSi alloy and it is also to be linked to the increase of the Rsheet value observed at the input power of 0.83 W just before the decrease where effectively, the composition is of the Al almost alone.

[0126] Results are represented on FIG. 5 where the percentage of Al is 12,98 the percentage of Si is 63,78 and the percentage of O is 23,24. FIG. 5 is a picture of Al transferred on mono silicon wafer, SEM details and EDX analysis of the composition. [0127] a) picture of the black <<coating>> at FP=0.83 W and overlap=85% [0128] b) detail of a) detailing the structures [0129] c) and d) are details of b) detailing the structures

[0130] The transferred material is black due to the formation of an alloy between Al and Si, Al and O and also between Si and O. In presence we may find AlxOy, SixOy and AlxSiy. As a result of this section we can conclude that black aspect and eutectic composition can serve for two others applications of this patent: [0131] a) creating black metallized silicon wafer for silicon based solar cells [0132] b) doping silicon based solar cells since any material can be easily used and especially copper to metallize the silicon surface.

[0133] 3) Morphology and Mechanics

[0134] Deposited Surface and Deposited Thickness

[0135] Thanks to the, ALICONA Infinite 3D optical microscope, we were able to measure on the whole laser treated surfaces of samples the mean values of the thickness of deposited Al. As described in Table 4 it appeared that the less thick shapes are lines. Knowing that we can easily make the process fit the thicknesses values as requested.

TABLE-US-00003 TABLE 3 Mean values (m) of thickness sorted by wafers crystallinities and shapes deposited Mean value of the thickness by type of wafer and by shape Mono crystalline Poly-crystalline Square 12.1 11.5 Cross 11.8 10.1 Line 3.5 2.1

[0136] Laser Impact Threshold and Heat Affected Zone

[0137] laser impact damage threshold has been determined as equal to 0.75 W when the overlap is 70% and the scan speed is 540 mm/s.

[0138] FIG. 6 represents a SEM image of the vicinity of Al transfer on a poly-silicon wafer in shape of a cross.

[0139] As it can be seen on that SEM image, there is no affected zone. The silicon is preserved. The process also preserved in that condition the Rsheet on the wafer. Indeed, a mean value of 20 /sq was measured on the wafer before and after the treatment in the vicinity of the cross.

[0140] Line Width and Spaces Between Lines

[0141] A series of lines of 200 m width with inter spaces of 100 m were made. For these first experimentations we did not focused on obtaining the best performances. The values cited are for what is relatively reproducible.

[0142] FIG. 7 represents SEM image Al lines transferred on mono silicon wafer.

[0143] Some best scores had been attained with patterns of 70 m width and spaces between of 100 m but the spreading was not so good.

[0144] Adhesion

[0145] Thanks to simple measurements with 3M 850 scotch (that is a classic method used in many depositions tests (Nedarka, J-F., PROC. 25.sup.th EPSE Conference, 2010) the following simple test was made: we used the different squared transferred on poly and mono crystalline silicon and with a 30 mm long tape of scotch (3M Scotch-Weld Acrylic adhesive 825) we tried to peel of the transferred material from the silicon wafer. The tapes were weighted thanks to an Ohaus Adventurer analytical balance before and after the peeling and we found out a small mean difference (made on ten samples 5 poly crystalline and 5 mono crystalline wafers) of less than 2 mg which is not a noticeable nor a significant amount. Indeed we can consider that the removal rate is of 0.02 mg/mm2 in this process.

[0146] C. Conclusion

[0147] This example, displays a direct process for free form metal (Al) deposition on mono and poly crystalline silicon thin wafers (200 m). Using specific positioning and/or clamping tools and IR pulsed laser, we determined the parameter ranges (focalization, power, speed . . . ) adapted and reliable for each form that enable to deposit, highly conductive (Rsheet less than 0.15 /sq) adherent (0.02 mg/mm.sup.2 loss of mass while performing a peeling test with the 3M Scotch-Weld Acrylic adhesive 825), stable metal composition patterns on mono and poly silicon wafers. We can also add that the performances of this process in terms of adhesion, composition stability and Rsheet are not time and environment dependent. Indeed, we included in the protocol to measure some samples on mono and poly silicon nine months later knowing they have not been specially protected from light and left at open atmosphere and at room temperature. These final measurements demonstrated the stability of the layers deposited as the values of compositions and Rsheet were the same.

Example 2

Method of Manufacturing Selective Surface Metallization of Silicon Textile by Laser Assisted Deposition

[0148] The receiving material is textile and the result is called e-textile or smart textile.

[0149] Experimental Key Parameters

[0150] The major experimental parameters are detailed in Table 4 below:

TABLE-US-00004 Parameter Parameter's type Range Pressure Environment Atmospheric Temperature Environment Ambient Space between donor Environment 10 to 100 m and acceptor Scan speed Environment 2000-2500 mm/s Pulse overlap Environment 75-98% Wavelength Laser IR range Frequency Laser 4-100 kHz Pulse shape & diameter Laser Gaussian; 60 m width Power Laser 14-18 W

[0151] The metallization of patterns for electronics on technical textile is made with aluminium as a donor material on polyimide and polyaramide and cotton textiles as receiving material. Several patterns are realized with different complexity and all of them conduct electricity.

[0152] A comparison is made between metallization by serigraphy, well known by one skilled in the art, to metallization by the present invention. Rsheet measurements arc as follows in Table 5:

TABLE-US-00005 R (/sq) mean values (by four points probe) After After abrasion washing process under Initial, under standard Receiving Metal donor/ just standard NF EN ISO material/ deposition after NF EN ISO 105-C06 Textile method deposition 12947-2 (A2S) Cotton Ag deposited 9 1350 36 by serigraphy Al deposited by 0.002 8.042 0.013 the method of the invention Polyamide Ag deposited 18 428 338 by serigraphy Al deposited by 0.001 0.035 0.118 the method of the invention

Conclusion

[0153] In first sight we can notice that the elements metallized by our technique are much more conductive than those metallized by serigraphy: the Rsheet values are up to 4500 times lower in our case (metallization of Al on cotton by our method vs. metallization of Ag on cotton by serigraphy). It means that by implementing the method of the invention we are able to produce good patterns with good electrical properties by using a very cheap material.

[0154] We can also see that the deposited patterns are more resistant to washing and abrasion tests than the patterns deposited by serigraphy. Indeed the Rsheet values exhibited are slightly lower in the case the deposition is made by our method. It can be said that in the particular case of polyamide textile the values of Rsheet do not evolve with the washing and abrasion test in the conditions of standards used.

[0155] Plus, we can say that there is homogeneity over a large surface of the metallization according to the method of the invention polyamide textile.

[0156] We demonstrated the effectiveness of our method to design and deposit complex patterns of metal surface on textile by using cheap material. These metallized surfaces are far better electrically conductive and far better resistant to abrasion and washing than those made by the well-known and commonly used Ag serigraphy on textile. That proves here the versatility and robustness of our technique.

[0157] It is understood that the present invention is capable of further modifications, uses and/or adaptations of the invention, following in general the principle of the invention and including such departures of the present disclosure as come within known or customary practice in the art to which the invention pertains, and as may be applied to the central features, set forth herein, and are encompassed by the invention set forth in the following claims.