TWI305422B - Process and fabrication methods for emitter wrap through back contact solar cells - Google Patents

Description

1305422 IX. INSTRUCTIONS: [Reciprocal References in Related Applications] This invention declares the US provisional patent titled "Surround Full Covered Back = Guarding and Manufacturing Method of Contact Solar Cells" on September 7th, 2004. Shen N_G7, 984 and _August u (4) entitled "Improvement and Manufacturing Method of the Extremely Contacted Solar Cell for the Extreme King", please refer to No. 6Q/7Q7, No. 648 Please take advantage of it. This application is also a second part of the US patent application. All applications are filed on 2〇〇5 2^3: Case No. 11/G5G, 185 'title "Back junction solar cells, manufacturing method" Case No. 11/()5U82, titled "Tilt-contact solar cell pole with self-doped contacts"; and case number ΐδ4, title "Empole = coated back contact type solar cell contacts" Manufactured, these applications are declared: US Patent Application Nos. 60/542, 390 and February 5, 2, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 Japanese application title "Manufacturing Process of Hidden Contact Battery Using Self-Doped Contact" $ US Provisional Patent Cap No. 60/542, No. 454. The descriptions of all of these applications and the scope of the entire disclosure are hereby incorporated by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a process for manufacturing a back contact tangent solar cell, and a solar cell produced by the method. [Prior Art] The transmission of the 1305422 solar cell has several advantages over the connection of the front and rear surfaces. The first advantage is that due to the reduction or rear-end connection == the light of the dot grid cannot be converted into an electrical h-contact than the high-high conversion efficiency. The second advantage is due to the two-pole ‘, white, and the same surface, the back-contact battery is cheaper to combine with the circuit. It is said that the current photovoltaic module group has a large cost saving with the back contact type battery. - The last of the back contact battery - the advantage is through - more - the appearance is better. Aesthetics are important for some applications, such as the integration of photovoltaic systems into photovoltaic systems that can turn on and off the roof. A typical lunar surface contact solar cell is illustrated in Figure i. The germanium substrate can be either n-type or p-type. Among the heavily doped emitters - (called _ _ 二 二 二 些 些 。 。 。 。 。 或者 或者 或者 或者 或者 或者 或者 或者 或者 该 该 该 该 该 该 该 该 该 该 该 该 该 该 该 该 该 该 该 该 该 该 该The shunt current at the surface of the miscellaneous surface is less passive. The light from the scales produces a loss of the carrier' and helps reduce electrical losses. The demonstration only emphasizes the characteristics on the back surface. There are several methods for manufacturing - back contacts Solar cells are cut. These methods include metallized winding (MWA), metallized full cladding (MWT), emitter full cladding (EWT), and post-contact structures. MWA and MWT have current collectors in the front ^ The grids are respectively wound around the edge or the cladding hole to the back surface to form a back-contact battery. The EWT battery collects the junction through the push-and-transfer 1305422 flow in the dream wafer ("emitter ") to the rear surface of the channel - a heavily doped region in the semiconductor device. The conductive 乂 / Μ a laser is drilled in the slab substrate, and then the emitter is formed on the rear surface At the same time, the hoof is formed in the system. The battery has a negative and positive bipolar collection junction after the solar cell. Table 2'. Since (4) most of the light on the front surface is absorbed, and therefore most of the #bonded cells require very high material quality', the carrier has sufficient time The self-rotating surface ship has a wire (four) joint at the rear surface = behind. Under the father, the EWT battery maintains a current collecting junction on the (10) surface to facilitate high current collection efficiency. The cake battery is disclosed in James ^Gee In the US Patent No. 5, Qian Tiehu "The Method of Making a Back Contact Solar Cell" is complete here. Various other back contact battery designs have also been discussed in many technical publications. In the patent case No. 5, 468, 652, the Gee co-inventor's f also has two special methods to show the four-sided contact-type solar cell model. The method of coordinating four pieces: US Patent No. 5,951,786 A thin-film photovoltaic module using a back-contact solar cell" and a "single-module combination" of the U.S. Patent No. 5^972' 732. These two patents disclose the practice of the present invention. The method and secret, and the complete introduction of (10) human face. US Patent = 6'384, No. 316 "Solar Cell Extreme Manufacturing Method" reveals another type of back contact battery design 'but implementation, its towel hole or The channel is relatively distant from the old rut with metal on the front surface to help direct current to the rear surface of the 1305422, and the hole is additionally lined with metal.

Eikelbomn et al., "Transitive Adhesives for Interconnected Solar Cells on a Structured Metallic Foil" appeared in the 17th European Conference in Munich, Germany, January 22-26 The Photovoltaic Solar Conference, discloses a method of fabricating a solar cell using a co-ignited Ag/Al alloy p-type contact, and is illustrated on the second through the fifth, as explained below: 1. Etching and cleaning the p-type germanium wafer 2.

2. Light P0C13 (n+) diffuses 4 (100 ohms/sq) on both surfaces. 3_ HF etching and cleaning. 4. The SiN layer 6 is deposited as a diffusion barrier on the two surfaces. This solar energy is shown in Figure 2 at this stage. 5. Drill the hole 8 for the 1 2 3 4 5 type contact and scribe the groove 1 for the p-type contact. 6. Laser damage is engraved and clean. This solar cell is shown in Figure 3 at this stage. 7. Heavy pock diffusion to diffuse phosphorus into the solar cell to form η++ diffusion 12. This solar cell is shown in Figure 4 at this stage. 8. HF for the moment. 1 - A paste of Α1 is printed for the crucible grid 16. 2 10· Print a metal paste for the n-type grid 18. 3 11. Co-ignite the joint. —p+ A1 alloy joint 2Q overdoping the ρ contact 4 ψ ++ May n diffusion. The solar cell is shown at this stage in Figure 51305422. This result suffers from the very poor conductivity of the alloy gossip grid.

Any back-cutting field can be battery-H == one of the joints is low. :;= :==r·,一动动动[Summary of the invention] The present invention is based on the method of providing a H-electricity rate::=; a relative conductivity type on the surface State-expansion = from =, formed from the front surface of the substrate to the substrate - a plurality of holes in the mosquito, from the back surface = diffusion and dielectric layers, the establishment of the package - guide state - In the region, the deposition-first-conducting grid is on the surface of the wire that is in contact with the junction t; and the step of depositing the second conducting gate on the surface after 2 o'clock with the hole. Preferably, the step of establishing includes, preferably, f-free bribes (four) 纟 a red clusters - (iv) hetero-based conductive grids preferably containing no such dopants. Provide-diffusion step ί Take the gas containing the exposed recording plate to the best of tons. Preferably, the gate is reconciled with the second conductive grid. The deposition step does not necessarily include depositing the dielectric layer on the front surface. The establishing step includes providing a second conductivity 1305422 on the inner surface of the hole. The method does not necessarily include constructing a passive layer: a step of the method between the front surface and the back surface or both. The method is preferably: the material is free to oxidize the surface or the passive layer is deposited on the surface. One of the groups of methods. The present invention does not necessarily include the step of coating the inner surface of the hole with one or more regions of the metal contact layer having the best package of nickel, wherein the coating is: after the establishment step and Before the observation step. The contact layer is the most used, 'Wei Jiaqi Jin. The method is not necessarily included in the removing step 1 θ for a second diffusion step, the second diffusion comprising a relatively conductive type 内部 the inner surface of the hole and the multi-view domain; wherein the establishing step Including overdoping the second diffusion. The present invention relates to a back contact type solar energy according to any of the foregoing methods - a genre-hoof-contact type solar cell, which comprises the best included recording, disposed on one of the substrates or the:: - or more Between the conduction of plums, wherein the wheel does not contain the invention and is also used to make the method, the method includes money for the square plate containing the surface-turning battery, and the deposition-patterned dielectric layer is in one of the electrical types. The semiconductor-based electrical type-diffusion is performed on a layer that does not contain #,上, and includes a relative derivative, a deposition-metal on the layer of::;::2, and igniting the metal. The dielectric side of the open portion is preferably the same as & screen printing. 10 1305422 The step of providing _ diffusion preferably comprises using a slit selected from the group consisting of * p(10) and qing. Preferably, the metal comprises a material - a conductive type of energy. Preferably, the depositing step comprises screen printing comprising one of the metals = the step of the article preferably comprises blocking the moon in the open part of the metal

Ming - the target is provided - a back surface contact structure for the back contact type tera-cell battery including a wide-gated line for increasing the conduction bond - the minimum P-type contact area and - the maximum_green or Extremely to increase efficiency. The present invention is a manufacturing method that provides fewer, more economical process steps to produce high efficiency solar cells. Other objectives, superiority and other applicable scopes of the present invention will be referred to below, and some will be known to the skilled person in the fourth day of the work, or The invention can be implemented by: learning. The objects and advantages of the present invention can be realized and obtained by means of the means and combinations particularly pointed out in the appended claims. [Embodiment] The invention disclosed herein provides (10) an improved process for manufacturing a f-side-reduction solar cell, and in particular, provides a more economical manufacturing process. It will be appreciated that while many different separation methods are disclosed, it is well known to those skilled in the art that the two methods of thief can be incorporated or varied to provide an alternative manufacturing method. It should also be understood that although the Type II and the example process procedures describe the fabrication of a f-contact fully-wrapped battery, some process procedures can be used to fabricate other back contact cell junctions 1305422, such as MWT, MM, or back-junction solar cells. This is the most common use of the day - the _ _ _ p difficult point (laser ^ '1) » on the pattern. Patterning—wire-to-print diffusion barriers are provided with _wafers—low-quality interfaces, such as those with poor passivation. The contact is formed by laser = integrated process, such as evaporation or (10), which can be used to deposit the diffusion barrier 1; the interface of the stone eve is like "preserving the spectrum". Also, in the standard screen printing process = general obstacle - generally before the implementation of the Wei Ze 3 diffusion before printing. By; _ after the diffusion of Shenlong diffusion barrier, the financial road - the road extended to the piano

The contact groove greatly improves the efficiency of the battery. Or P-patterning, such as 曰d彳 or direct U-day Japanese fine cutting machine, diamond scribing, or inkjet printing HF _ _ _ _ _ _ _ _ _ or by 4, '·罔 use-laser to pattern the p-type contact number ==:: shape and its energy solar power ^:=Γί1ϋϋ-range, especially the efficiency of the broken battery by 5 fine geometry The shape is second, and the area of the (10) blade and the p-type contact is enlarged. ",, the heart is used for the printing step is more relaxed. This is to 〇〇 (W is wide and on the surface is side _ groove (10) to and on the surface is 5: wide 盍; =: error left - * knife, μ see" for the alignment ~ again Conversely, 'all the printing passes in the bank Φ, 200:;!- 12 1305422 in the barrier opening. This number is closer to the width of the Ag grid, and leaves a marginal error. 乂乂 二 discloses the use of A1 alloy or occupation A procedure for doping the p-type contacts, however, other p-type dopants may be used, including but not limited to Ga and h. Similarly, any n-type dopant may be substituted for boron. For the purposes of the present invention, Preferably, some types of S are used to sneak into the p-type pair to electrically insulate the 接-type contact from the η-face of the record. The affluent issue is to split the η-type at its junction. Ρ-type diffusion, which can also be affected by the p-type metal. 6-8 _ shows the solar cell made according to the lower _ diffusion process. 1. Etching and cleaning the wafer. 2. Light 〇 〇 α diffusion (best About 7〇 to 14〇〇hms/sq) on the surface 2. 3. HF etching and cleaning. 4. Oxidation or deposition of the passive layer (not required). This layer may be desired before Surface, the back surface, the wafer side, or any combination thereof. 5. 'The SiN is a diffusion barrier on the two surfaces. · The n-type contact laser is drilled and is a p-type junction lake. Ditch or pit 7. Laser damage etching and cleaning, preferably using Na〇H. 8. Printing, drying, and igniting P-type ditch or boron-containing paste 24 in and above the pit. The solar cell is at this stage. It is depicted in Figure 6. 9. Obstetrics - ^ ^ Heavy P0Cl3 diffuses to 20 ohms/sq) for diffusion into the 13 1305422 solar cell to form n++ diffusion 12, or application - containing paste The object is to the hole and spreads. Preferably, the boron is simultaneously diffused into the wafer to establish a W layer. The advantage of using a POC13 diffusion rather than a phosphorus paste in the pores is that the gas supply - more - diffuses into the wealth. This solar cell is depicted in Figure 7 at this stage. 10. The HF residual (not necessary in a particular case)' to remove the shaft-containing material and the paste-containing material (if used). Lu 11. Printing the Agn metal grid 18 and the ρ metal grid 28 to contact the n-type and p-type regions, respectively. 12·Commonly ignite the joints. The solar cell will be depicted in Figure 8 at this stage. Note that in this process, the two Ag-containing pastes preferably have a sufficiently low activity to prevent pinhole defects from forming in the SiN layer, but still have power to separate the holes and the holes in the respective electrical contacts. With ^ layer. The (10) layer can be made as thick as needed to prevent the paste from penetrating it; the layer is preferably • between about 30 nm and 140 mils thick, and more preferably about 8 〇 nm thick. The contact layer may not necessarily comprise one of the high quality metals deposited by thin film deposition techniques including, but not limited to, sputtering, (10), or evaporation. These technical deposits have ideal properties to contact the slaves with very secret metal layers. This problem is quite expensive to break film deposition and requires a separate-separation patterning step. One of the processes for the use of thin film and metallization for back contact solar cells has been described by Leak et al. < US Patent Application 1G, U.S. Patent Application, 2nd Edition, 52nd A1, "Metal Contacts for Solar Cells" Structure and manufacturing method". 14 1305422 The contact layer may contain _. Sintered Nl _ 辑 ^ 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有The Ni generally endures during the sintering step: • Solid state reaction to form a lithograph, in which case the lithic nickel is connected to the ‘point layer. The Ni junction can shunt the junction to have a more state problem than burning the Ag junction. Also, 11 is optimized for bribing, which avoids deposition on existing SiN (or other dielectric) layers. The non-electric mine m is used for the complete use of gold. • Some of the Shixia solar cell manufacturing processes. An additional advantage is that the ore Nl improves the interface' such that Ag, tantalum, or other paste ribs form one of the joints with higher integrity. One of the problems with the use of electroless plating for all metal-plated battery technology of δ hai is very low. However, the present invention requires only a thin layer of the electrical contact, preferably a thickness of 10 to 1000 nm (and more preferably about 1 〇〇 nm). A screen printed gate is then preferably applied to the conductor. For this application, a low temperature point Ag paste is preferably used to reduce the metallurgical interaction with the μ junction and the lower Shi Xi. Alternatively, a screen printed Cu grid can be used. Although the Cu tilt is more susceptible to oxidation than Ag, it is preferably capped with a non-oxidized metal or an antioxidant. Alternatively, a base metal, such as Ni, can be printed, and then a more conductive metal is plated (without electromineralization or electro-recording) to increase the conductivity 'including but not limited to > Ag or Cu. When money nickel is incorporated into the previous boron diffusion EWT process for mineralization nickel junctions, the following steps are preferred after HF in step 10: 15 1305422 11. Plating (preferably electroless) and preferably sintering Ni contact layer 34. This solar cell is shown in Figure 9 at this stage. 12. Print Ag n-type gate 18 and ^ P-type grid 36 (preferably for two-pole grid use. Low-temperature paste) and ignition/sinter junction. In this embodiment, it is preferable that the n-type and the p-type contact use the same metal, or different materials can be used. The solar cell is shown in this stage at this stage. The thickness of the silver or other metal can be printed, or it can be best to use the thin metal joints that are not built by Wei or Wei. The subsequent metal need not contain the same metal or alloy as the previous print. Nickel plated contacts can also be used to bond an A1 alloy p-type joint as shown in Figures 11-13. The best steps include: 1. Etching and cleaning the wafer. 2. Light p〇cb diffusion (preferably about 7〇 to 14〇〇hms) on the two surfaces. 3. HF is engraved and cleaned. • 4. Oxidize or deposit the moving layer on - or multiple surfaces or sides (not required). 5. Deposit SiN on the two surfaces as a diffusion barrier. 6. Drill holes for n-type contacts and divulate or pit for p-type contacts. 7. Laser means bad button engraving and cleaning, preferably using Na〇H. 8. Heavy P〇Cl3 diffusion (preferably about 10 to 30 ohms/sq), or apply p-containing paste to the well and spread. 9. Print a paste for the p-type grid 16. 1305422 11 in the picture. 1Q.:=:==== 11. HCI and HF etching to remove the A1 wire surface oxide. 12. 13. Perform the (no electricity) button Ni. The solar cell is shown at this stage in sintering to form Ni contacts 34 in Fig. 12.

14. Print Ag η-type gate 18 and Ag p-type gate 36 (preferably a two-pole grid using a low-temperature Ag paste) and ignite/sinter the joint (or metal with no electricity or bell metal). The solar cell is shown in Figure 13 here.

Ni is formed - a low impedance junction to doped Si, which allows for minimization of the p-type contact region and low temperature Ag. I want to - low activity (four) Hu, so that the SiN and Shi Xihua nickel layer is not penetrated. In the method of the present invention, there is a potential shunt where the heavy p+ junction diffuses into contact with the back surface n+ diffusion; see examples of Figures 10 and 13. In addition, the positive bipolar Ag gate potentially contacts the back surface n+ diffusion, thereby shunting the solar cell. Most desirably, since the two materials form a p_N junction diode, there is a shunt, and there is no blocking and only a minimum channel. However, these problems can be completely avoided by including an extra step to place an undoped region between the back surface n+ diffusion and the p+ junction diffusion, preferably using a low cost process such as screen printing. An example of a process is as follows: 17 1305422 I remnant and clean the wafer; 2. print the paste forming the dielectric material; 3. ignite the paste to form the dielectric; 4. clean and etch the surface ( not necessary). 5. Perform light (for example, 7〇 to 15〇〇hms/sq) to spread on the two surfaces. 6. The residual oxide;

· / Children's power is tied to the two surfaces. Alternatively, other dielectric materials (including but not limited to 1^2 or private 〇5) having a large refractive index, a treatment with a stone shovel, and a slave shovel may be produced. 8· is the η-type channel laser view, and depends on the p-type connection. 9. The remaining engraving shots are removed; .P brushing other p-type dopant diffusion sources into the p-type laser resection features,

〇hms/sq) in the stone mouth; U·execution weight (for example, 5 to 30 〇 hmS/sq, and preferably < 2 〇 diffusion to dope n-type channels and drive boron to p-type contacts to open 12 Etching the diffusion glass; and applying and annealing the negative and positive polarizations. The method preferably includes or does not have to separate the P+ and n+ regions to avoid shunting. The other comprises the following steps: 1 • P-type twin For drilling holes in a circle, it is best to use a laser. 2. Etching and cleaning the wafer. This step may include an alkali etching 18 1305422 匕 3 驮 etching to form the structure of the front surface to improve the absorption process. The surface of the wafer is formed to form an n-type layer 1 〇 4, preferably using a POLCl 3 or another type 11 source, and preferably in the range of about 45-140 ohm/Sq. 4 · Collar diffusion glass. - Laser, residual paste, a mechanical method, etc., for the P joint on the back surface to scribe the opening. Since there is no chance to etch away, it is best not to introduce the defect into the stone in the next step. Preferably, the patterned dielectric layer 106 comprising SiN, titanium or tantalum oxide or the like is on the front and back surfaces of the wafer, and the thickness is preferably in the range. About 4 〇 nm to 150 nm. This layer is preferably used as a metal and diffusion barrier on the back surface, and one of the front and back surfaces is optically coated. This layer is preferably not deposited on the hole or hole. The solar cell is shown in Figure 14 at this stage. 7. Perform a second scribe, direct alignment and centering the first scribe, but with a smaller diameter or width. The solar cell is at this stage. Shown in Figure 15. 8. Screen-printed p-type paste paste 124 'for example - & $p paste in the scribed region and by diffusion or alloy p+ junction layer 126 is in the second scribe opening. The solar cell is shown in Figure 16 at this stage. 19 1305422 9. If necessary, etch the glass or other p-type source. 10. Conductor paste or metallized metal The p-gates 128 and n are torn m. The solar cell is shown at this stage in Figure 17. This method results in approximately only the Ρ+ region formed on a small portion of the wafer created by the second scribe step. The portion of the dielectric layer in the first-off phase separates the η+ region on the back surface. The good process does not use a separate patterning step for the p-type contact. Instead, the ρ difficult leg field is defined simultaneously for (4) diffusion patterning. The process preferably includes the following steps: 1. Laser drilling. Etching and cleaning the wafer. This step includes an alkali etching, or does not necessarily include an acid etching to form the structure of the front surface to improve the absorption process. 3. Screen printing forms a diffusion barrier pattern (not adjacent to the hole) a dielectric material on the rear surface. This forms a patterned phosphorus diffusion during the phosphorus diffusion step. The pattern preferably includes the opening of the subsequent germanium metal contact, especially if the dielectric diffusion barrier is not easy Etching and the bismuth metal are not easily ignited through the diffusion barrier and the passive material on the back surface. 4. Thermally anneal the dielectric paste (for example, about 500 to loooc for about 5 to 30 minutes). 5. Perform phosphorus diffusion, preferably using a gas source (eg P0C13, ρΗ3, etc.). Preferably, the diffusion is an intermediate diffusion; that is, light enough to provide a good light 1305422 in response to the front surface, but heavy enough to provide sufficient doping for the n-type contact. 6. Perform etching to remove the diffusion. The oxidized phosphorus glass left behind. Suitable etchants are known in the art and may include water HF chemical etching, i.e., vapor etching, or various plasma surrogate chemistries.

7.···························································································· 7G money nm. The nitrogen cut is preferably deposited by plasma enhanced chemical vapor deposition (PECVD) as a disc alloy containing shi, nitrogen, and niobium (which is shown as -SiNx:H or _). These membranes are known to provide passivation of the surface with a large number of defects and thus provide energy conversion efficiencies for the tantalum solar cell.

8. Deposition-gasification chopping or other dielectric layer on the back surface, preferably η (not required). This layer passives the back surface and thus improves the solar cell efficiency. This step can be performed in synchronization with step 7 or in step 10 of 9_ for the 接-type contact and grid ("p metal") screen printing metal, preferably using a paste (preferably - or not necessarily UA1) 10) drying the ρ metal; printing, preferably about 1 〇 to 11. for the n-type contact and the grid (preferably 竑) screen 50 microns thick; 1305422 12. igniting the metal; and 13. testing The solar cell. In this method, the P-type metal preferably prevents diffusion of phosphorus (10) in the dielectric barrier opening to form the ohmic junction. One of the configurations of this configuration is described in the 18th U. The advantage of this process over conventional techniques is that only one phosphorus diffusion is required and the hole is drilled at the beginning of the process (which eliminates a laser damage etch step), reducing process cost. The back contact EWT battery can also be fabricated using self-doping metal in a process similar to a hidden contact cell manufacturing process. Care must be taken to ensure that the self-doping metal fills the trenches and holes, making continuous impedance a problem. An example of this one is as follows: 1. Surname and clean the Si wafer; 2. Laser-etch the n-type trench and drill it on the back surface; 3. Light (8〇 to 12〇〇hms/sq ) scale diffusion; 4 · HF money engraving, remove the phosphorus glass by self-diffusion process; 5. by PEVCD or low pressure chemical vapor deposition like _ deposition of nitrite; 6 · laser scoring the surface of the p-type trench or Pit; 7. Fill the n-type trench/hole and p-type trench with n-type and p-type self-doping metals respectively; and 8. Co-ignite the metal. In any of the above embodiments, the large area of SiN or other dielectric 22 1305422 on the back surface allows the best and the same contact line to be as wide as possible (to carry more current) without actually contacting the germanium wafer . One allows the maximization of the n+ emitter and narrows the area of the p-type junction, thus increasing carrier collection efficiency. The percentage of the total rear surface area is occupied by the P-type contact. Also, in all of the embodiments herein, many methods or variations may be used, including but not limited to the following. Miscellaneous methods can be used, such as chemical or plasma mash!, hot migration materials, which can be formed using laser drilling. Some of these method towels are described in Patent Application No. 1()/Foot, (10), entitled "Emall Full-Coated Back Contact Solar Cell on Thin Hard Wafer", US Patent Application _M87, title " "The manufacture of a back contact type solar cell using a thermal transfer to establish a conduction path", and the international patent application PCT/1 class/2_, entitled "Backside contact type solar cell with integrated conduction path and manufacturing method", all in This is incorporated by reference. Can _ (four) m_ shape, tons of fine _ case. A silicate or another type of dopant source can be used to form the p+ junction. The size of the scribed groove must be chosen to reduce the balance between the contact area and the recombination speed. Finally, it is also possible to __select the emitter process' where the stray is lighter on the front surface than the channel towel or the rear surface. This can be re-diffused by the smear of one of the front surface on the front surface to diffuse the hole and the back surface, and is etched by =. This can be accomplished by a wafer having a single-slit (e.g., 23 1305422 dual-load) in which the front surface of the manned surface faces the diffusion on the surface of the contact. 2, in addition to the battery, these procedures can be very simple to manufacture:: simply scribe pits or trenches, instead of the n-type junctions in the ^ Γ妾 太阳 sun money pool with 贞 and positive two-pole current collection close to The light absorbed at the front surface is created such that the width of the device at the junction is spread. De (4) after the device

= face joint; the cut wall energy battery has a negative pole and a positive pole and a collector grid on the rear surface, the negative pole and the positive pole grid must be electrically connected to each other. The _ must be _ current to the bond pad or rod. A metal sash is attached to the bond pad or rod to connect the solar cell to an electrical circuit.

There are two geometries for the gate of the back contact cell. In the "forged back contact" (IBC) geometry, the negative and positive conductivity type grids form a forked comb structure (mth and 19B). This structure is simple to implement in production, but suffers from high continuous impedance due to long gate lines with limited cross-sectional areas. The length of the grid line is reduced by the equivalent of the 阻抗 impedance - the ❹ bar is reduced (Fig. 20). However, 'because the optical flow collection is reduced in the area above the rod, the rod reduces the effective main field H to interconnect the phase (four) face contact solar cell geometry to make the cell with the rod in the center of the cell become more complex' Rather than the bond pads on the edge of the battery. IBC patterns can be easily produced using low 24 1305422 cost-effective production techniques such as screen printing. The second geometry for the grid in a back contact cell uses a multi-layer metal (Fig. 21) (Richard M. Swanson, US Patent 4'234, No. 352, approved by Richard M. Swanson, February 18, 1980 Photovoltaic converter and battery used therein"). The metal layer is vertically stacked with a deposition (4) that provides electrical insulation. Since the metal covers the entire back surface, the multilayer metal geometry can be more easily achieved than the IBC geometry - a lower continuous impedance. However, in addition to the metallization step, this structure requires two dielectric depositions ("the "-" and "second" layers) and the patterning step. In addition, multilayer metal requires very expensive thin film processing techniques to avoid pinhole defects in the dielectric insulating layer that may cause Wei shunting. SUMMARY OF THE INVENTION The present invention provides a second embodiment for reducing the continuous impedance of a preferred IBC grid pattern (having the bond to the edge of the cell) in one of the back contact type shi solar cells.

In an embodiment of the first brother, (4) suppressing the city, so that the width 2: increases until it reaches the edge of the battery. This is caused by the same ratio of the current carried by the grid increase in the cross-section of the grid: the hua cover portion reduces the continuous impedance. The narrowed width pattern in the negative two-pole current collecting grid 520 2 preferred embodiments are shown in Figure 22 (drawn in scale). Figure 23 13 = genus 'that is, the metal 530 plated through the metal of the contact, which is a section of the 耽 grid of the 22nd surface on the surface after the electricity is 25 1305422

Decision-best-test or (iv) calculation is called decision, with -::=r:=: the continuous impedance of the gate is 125% and i25_ = is counted. The spacing between the same two poles is chosen to be 2 mm, and the metal back cover portion is chosen to be the side. The gate line is a width M geometry, having a width on one side, and the gate line is increased from 2〇〇 to the narrowed geometry. The continuous impedance is such that the narrowing is less than the fixed width IBC geometry. Note that other narrowings can be used as needed; for example, the grid lines may be narrowed from 250 to 55 feet wide. The -second implementation of the impedance can be reduced by making the gate line thicker. The thickness of the screen printed Ag paste grid is limited by the physical properties of the paste and the screen. The best geometry of the IBC gate (Fig. 19A) that allows edge collection is to be relatively thick grid lines (>5-) to allow current to be conducted through this large size with acceptable helium loss. This solution can accommodate "web printing. Two preferred ways to increase the thickness of the gate line of the printed Ag IBC gate are by soaking the IBC cell to a molten solder ("solder"), or by forging: Electrode or no secret) on the grid. Soldering is a known process used by a (4) solar cell manufacturer to make a conventional tantalum solar cell. The temperature of the molten solder is shouted according to the compound of the solder, but is generally less than:. In one embodiment, the implementation of the -Sn:Ag solder is performed to reduce the printed Ag gate line 26

1305422 H ^ Many metals on the scale without electricity. Cu and Ag are especially useful. The other side of the miscellaneous line is reduced in pressure in the battery. Since the final conductivity will establish the metal to the mosquito, it is best to print a thin film on the side, and ignite it at a high temperature ("3"). The duck is very warm in this layer, which is particularly attractive. Instead of the ordinary or the present invention used in the foregoing examples, the reactants are repeated in a similar manner to the 7 or operating conditions. In particular, the person in the county will understand that the specific manufacturing steps and changes can be modified: additional steps are taken, and the scale is removed from the invention. ^ This post is specifically described in detail with reference to this preferred embodiment, ==r changes and modifications of the present invention: On ====- The complete disclosure of the case is hereby incorporated by reference. ~, _ should apply 27

Claims (1)

Γ305422 November ★日修 (years old) 正本10, the scope of application for patents: - a kind of green used to manufacture - back to the battery, the steps included in the financial method are: provide the semiconductor-grade with the - conductivity type; Providing a back surface-containing phase; depositing a dielectric layer on the back surface; Formed from the silk - silk secret light of the New Zealand - County Di complex number of holes; self-facing surface - or township domain shift _ green layer and the dielectric layer; establish one of the first conductivity type Or a plurality of contacts in each of the one or more regions; a deposition-first conductive gate on the rear surface of the electrical contact with the contact; and a second conductive gate in the hole The back surface of the diffusion joint. 2. The method of claim 1, wherein the establishing step comprises doping the substrate with a dopant. 3. The method of claim 2, wherein the dopant comprises one element selected from the group consisting of boron and aluminum (A1). 4. The method of claim 2, wherein the first conductive thumb does not comprise the dopant. 5. The method of claim 1, wherein the step of providing a diffusion layer comprises exposing the substrate to a gas. 6. The method of claim 5, wherein the gas comprises p〇cl3. 31. The method of claim 1, wherein the first conductive grating is combined with the first conductive grid. i - the method of the invention wherein the deposition step comprises depositing the "electrical layer on the front surface, and the establishing step comprises simultaneously providing a weave-like surface of the chicken-inclusive layer having a relative conductivity. The method of claim 9 or claim 2, further comprising a passive layer on one or both of the front surface and the back surface. The method of claim 9 wherein the constructing step comprises a method selected from the group consisting of oxidizing the surface or depositing the passive layer on the surface of the filament. Such as the scope of patent application! The method of the invention, further comprising the step of coating the inner surface of the aperture with one or more regions of the metal-bearing metal contact layer, wherein the coating step is performed after the establishing step and the depositing. 2. The method of claim 4, wherein the contact layer comprises brocade (10)). The method of claim 5, wherein the contact layer is plated with gold by electroless plating. 14. The method of claim n, further comprising the step of providing a second diffusion layer after the removing step, the second diffusion layer comprising a relatively conductive bear on the inner surface of the hole And the one or more regions; wherein the establishing step comprises overdoping the second diffusion layer. 15* — A back contact solar cell comprising: a semiconductor substrate comprising a first conductivity type; 32 1305422 - a first-difference (four) 'deposited on the back surface of the semiconductor filament - a pattern having a relative a conductivity type; a dielectric layer deposited on the back surface; the plurality of holes ' extending from a front surface of the board to the back surface of the substrate; - or a plurality of contacts' The first conductivity, which includes regions of the back surface that are not covered by the first diffusion layer or the dielectric layer, the contacts including one of the opposite conductivity types; - first conduction a gate deposited on the gate including the contacts, and a second conductive gate deposited on the rear surface of the electrical contact including the second diffusion layer in the holes . 16. A back contact solar cell comprising: a metal forging, the layer being disposed between one or more doped regions of the wire and one or more conductive gates, wherein the conductive grid Does not contain this metal. Π· For example, the back contact solar cell described in claim 1 is incorporated herein by reference. 18. A method for fabricating a back-fed solar cell, the method comprising the steps of: providing a one-and-first conductivity type half-new; depositing a patterned dielectric layer on the back surface; Providing a diffusion layer comprising: a relative-conductor type on an open portion of the surface of the 33 1305422 after being not covered by the dielectric layer; a dielectric layer on the open portion of the 1H; and depositing a metal in the opening portion and The metal is ignited adjacently. The method of the invention wherein the deposition step comprises a screen 19. The dielectric layer is printed as in claim 18 of the patent application. 2 〇 ^ Please Mei Qing 18 methods described, the wealth provided - the surface of the layer 匕 3 to make the county free coffee all over the gas - gas. The method of claim 18, wherein the metal comprises one of the first electrical forms. 22. The method of claim 21, wherein the depositing step comprises printing a paste comprising the metal. 23. The method of claim 18, wherein the igniting step comprises preventing diffusion in the open portion with the metal. % 24· A back contact type solar cell comprising: a semiconductor button comprising a first conductivity type; a patterned filament deposited on the surface of the button; a expansion comprising a relative conductivity The pattern 'includes a portion of the back surface that is not covered by the dielectric layer; and the metal layer' is deposited on the portion and on the dielectric layer adjacent the portion. 34