JPS58151070A - Solar battery and manufacture thereof - Google Patents

Abstract

PURPOSE:To contrive the improvement of photoelectric conversion efficiency, by making hydrogen exist in the neighborhood of the interface between an N type Si substrate having a junction and an Si3N4 film. CONSTITUTION:An N<+> layer 12 is formed by introducing P into the P type Si substrate, then an Al film is evaporated on the back surface of the substrate and sintered, accordingly a P<+> layer 13 is formed in the P type substrate into an electrode take-out layer, and the improvement of the efficiency of a solar battery is contrived by the effect of the back surface electric field. Successively, by the three layer of Ti-Pd-Ag, an electrode 14 is formed over the entire surface of the back surface, and electrodes 15 are formed on the surface in fine lattice form. Next, the substrate is kept at approx. 300 deg.C in vacuum, then, with poly Si as a target, argon, N2, H2 are introduced, and thus a reflection preventing film 22 of Si3N4 containing H is formed by a sputtering method. By the H added-reflection preventing film, the speed of recombination of carriers on the Si surface can be decreased, and therefore the conversion efficiency of the solar battery is improved.

Description

[Detailed Description of the Invention] (Technical Field of the Invention) A solar pond and its manufacturing method 4; Engagement, 脣 (Improving foreshadowing near the acupuncture surface of a two-semiconductor rare plate to improve photoelectric conversion efficiency A solar cell and its manufacturing method (two related items).

(Technical Background and Problems with RSO) Conventionally, for the purpose of photoelectric conversion of sunlight (2), solar cells with the shape shown in Figure 1, which are made of wood such as silicon single crystal, have been put into practical use. .For example, shore depth Q, 3 to 0.4
Tables 1O, 2 to 0. of Parrot Pm silicon single crystal substrate (1).
A male diffusion layer (by a method such as thermal diffusion≦2) is applied to the 6 μm layer, and a lattice-like, comb-like, net-like, etc. ), base P
1jJi V 9 = y Single 1i Jas 'y EVA (-total dE l-b Tari lkm kame m (47 is formed. In the above example, the upper 2♂ layer of P-certified silicon is provided. On top of n-layer silicon (a structure with two r layers can also provide the same timing characteristics), in the case of a solar wax pond with a typical mating structure, the substrate surface il [1 ( 61
In order to reduce the reflection loss of sunlight incident on the surface of silicon (= silicon surface), a so-called anisotropic etched surface is formed, which has a concave curved surface in the form of a four-dimensional structure with a large number of small values. By increasing the yield of sunlight by the Hiranzu-like elemental multi-summer reflection C2 of silicon 1IRTjIi,
An attempt has been made to coat the surface of the silicon wafer with an anti-reflection film (6). Surface (2 people) When sunlight is incident, part of the sunlight is reflected on this surface, and the reflected ratio is (n-1)''/(n+1), where the refractive index of silicon is n.
)", and if n = 3.7, it becomes approximately 0.3. For this reason, the surface of the silicon wafer is coated with a transparent anti-reflection film that has a refraction of 54A, which is between that of air and silicon. It is thought that it is possible to reduce the loss by half or more, and the efficiency of the solar 1i!c pond is the same as above (because it is a double effect, we have used various materials such as Sing * SiO * TiCh + T&tCh), vapor layer, sputtering, and spin. Various thin film forming methods such as cord, staghorn, CVD, etc. have been used to form anti-reflective films.

In addition, various efforts have been made to reduce the reflection loss of sunlight and increase the photoelectric conversion efficiency of the 42-solar pond, but at present the efficiency is not sufficient, and it is only 10 to 13 solar cells at most. Yes, there is an excerpt of the 5 IJJ rate.

(Object of the Invention) The present invention has been made in order to improve the above-mentioned drawbacks, and an object of the present invention is to provide a solar cell with improved photoelectric conversion efficiency and a method for manufacturing the same.

(Summary of the invention *) Next (: Detailed explanation of the present invention 0 Invention (First, our discovery to reduce the M bone velocity (hereinafter abbreviated as S) on the surface of a cow exposed substrate 4; C: Next, a silicon substrate will be described as an example.

S in silicon generates a pair of two electrons and one hole in silicon qua7a by laser diode light, and micro'I! L
A well-known method (for example, applied physics 11N4
Determined from Volume 9, page 1192 (2nd entry) 42. 4
! ! The result of measuring S on woodcutter's silicon wafer was 36 tl≦2. In addition, when the conventionally widely used anti-reflection film of camphor was carved into the surface, the results of S-j were as shown in (a) and (bJ. tal is the substrate (When using two NtJM silicon cz single crystals, (bl is when using Pya silicon cz single crystals. In both cases, S is before film formation (two comparisons)
2 (&J It's getting very hot, and even if the amount of light absorbed by the anti-reflection effect increases, the loss due to recombination can sometimes become larger.

Next 6: Discovery regarding non-5I5@ (2 related experimental results are shown.

Table 3 ta) shows the true
VD flow (chemical vapor deposition method), magnetron sputtering method containing hydrogen as sputtering gas, and conventional atmospheric pressure CVD method as a comparative example (when silicon nitride was formed from 2). j), fit 1 (
b) is the result using the same wafer as in Table 2(b). Gutsuzu-W Films formed by CVD and magnetron snorting have a significant decrease in S content. Registration (2Nf)
In the case of f1 Ueno-- (2 is remarkable. Comparative layer of infrared ridge yield spectrum; according to it, hydrogen compound 1 is included as a reaction gas (= despite the atmospheric pressure CVD method (2 is hydrogen Magneto a) sputtering, although its presence is not seen.
The presence of hydrogen was observed in the film formed by plasma CVD. The surface O dangling bonds and trap levels are inactivated by hydrogen C diazitter formation, and in the film (dihydrogen ions accumulated in the form of dihydrogen ions form an internal s'dL field in the surface WM area, causing a small number of It is understood that S is improved as a result of preventing carriers from reaching the surface.In the present invention, instead of the conventional antireflection film, a film containing ζ dihydrate is used to reduce S≦2S. In order to achieve the above-mentioned in order to lower S, ■inactivation of dangling bonds and trap levels due to hydrogen, and polishing of S″4 field within the surface due to electricity During biconversion formation (introducing bihydrochorions and leaving them in a valid state (== in the membrane or on the substrate), it is essential to leave them in an effective state. Heat treatment at about 400'O or more (substrate temperature is also important because hydrogen is removed and S is increased.Atmospheric pressure CVD method (no dihydrogen was observed in the film)
This is probably because the mating substrate m[ of this method is close to soo'o or more (-).

Considering the cause of the decrease in S, there is no need to limit the material (silicon nitride).
If the material has a permeability, dihydrogen is present in the membrane when formed;
Introducing ζ: More similar effects can be obtained. As an example of this, the inventor has developed a method using magnetron sputtering.
The value of S is 212 by adding hydrogen to the stomach of a goose.
Successfully lowered 0 cm/sec l=12. Hydrogen was introduced using an ion gun (
This was achieved by forming the film while implanting hydrogen ions. In the case of hydrogenated silicon, hydrogen is included as an essential element in the gas, which is different from the T&tOs example mentioned above. Purpose C of the invention is fully fulfilled.The method of forming the antireflection film and the characteristic state of the film and the boundary between the film and the silicon wafer that appear as a result of the formation method are basic (= conventional solar cells). It has the same configuration as .East (=
The invention is even more effective than C when the original silicon before forming the anti-reflection film has a large S content. Incidentally ζ two mosquitoes are widely used, for example, %ws56
- Specification of No. 126793
is 3000 to 4000 cm/sea, but the anti-reflection coating of the present invention can be reduced to less than 1000 cm/sea. In crystals, grain boundaries O dangling pons,
The local level due to de
It was thick at 000. It has also been found that by forming a second anti-reflection g, it can be reduced to 1000 or less (-).

(Embodiments of the Invention) Next, embodiments of the invention will be explained with reference to FIGS. 2 to 5.

Example-1 First, as shown in Fig. 2, the thickness is 111, and the thickness is 20.
A boron-doped C2 single crystal semiconductor substrate of Pli with a resistivity of 0 μm and a resistivity of 1 Ω is prepared. It has a diameter of 3 inches and has a 114-sided polished finish. After washing sand, 1 layer (2 layers)
) is formed on the substrate-side light jIIli@i-. For this reason (=
Deposit phosphorus at 850°C using phosphorus oxytrichloride pocz in the gas phase for 5 minutes, followed by a drive-in process for 2 minutes. The Imperial Palace also once appeared in the customary region of impurity addition, the so-called multi-defect layer (dead layer).
er) is removed by etching to form a junction with a moderate surface mirror layer and a junction depth of 50.2 μm with little damage.

Next (: Back surface of substrate 114I (Nialiumuminum film is formed).

By irradiating a magneton beam with an accelerating magnetic pressure of 3 KV in a vacuum of less than I x 10-'' Torr (with a beam of 2 A of pure [99,99-inch aluminum evaporation source)] The so-called magneton beam evaporation method, which involves evaporating aluminum and placing the substrate in the same vacuum chamber (double-forming) may be used. However, in order to increase the adhesion of the film, the temperature of the substrate during deposition of 4 m4 was set at 300". A 4 μm O film was formed at an evaporation rate of 3000 m/win.

Subsequently, this aluminum film is fired. in this case,
At 830°C in an atmosphere of 50% oxygen and nitrogen tAsos (9
) 4 seconds into the wafer of P”
In order to form a column and remove the electrode (both 2 and 4
2. Since 吏ζ2 brings about a back surface electric field effect called BSF, it is possible to improve the efficiency as a thick 1lII'4a. Next, remove excess aluminum and its oxides using salt and salt to expose the p''mu3 surface.

Subsequently, a conductive surface electrode I and a negative surface electrode ◎ are formed.

The electrode on the back is P+/1μ4 (21000^ titanium U).

IS is made by vacuum evaporating 500 λO bardium αη, 10 μm m−. The corner surfaces are formed into a lattice-like fine three-layer structure by repeating vacuum evaporation and photoetching. Ingredients for sea bream.

The composition of the rhinoceros is titanium Bl 1000 A, □: radium (to) sooX, and gυSum.

Antireflection wI&(2) was formed as follows. Wafer 7a! Danetron Spatsuta* [4; Additional Vacuum [
After the temperature was once lowered to below I x 10-" Torr, a gas was introduced. The sputtering gas had the following composition:
x 10-' TOrr *Hydrogen 1 x 10-”T
orr. Target (second is 8-inch polycrystalline silicon, high frequency strength is IKW, -4 plate temperature is 3QO'O (two is hydrogen-containing silicon nitride JIA)
was deposited. The film thickness was 700^.

The refractive index was 1.95 to 2.0 in the visible light range, showing good antireflection effects. As a result of the well-known infrared spectroscopy method, the absorption of ionized hydrogen in the film and hydrogen integrated with the silicon substrate was detected. .

Next, the surrounding area of the silicone wafer was etched with a nitrile-based etching solution.
c) For example, Toshi Silicone Company #! JCB-610
By drying the silicone rope in Step 8, a thick wax pond is created that does not deteriorate even after long-term use.

In this way, by forming an anti-reflection film containing dihydrate, it was possible to reduce the carrier velocity in the silicon area.As a result, the incidence surface was reduced.
When bright light with an intensity of 0 mW/m'' is incident, it is possible to obtain a solar cell with an ambient voltage of 0.61 V, a short-circuit source, a magnetic tlL density of mA%, and a conversion efficiency of 16.5. This was compared with the column evaluation results 42 under the same * conditions of a cell in which the antireflection film was made into a conventional hydrogen-free Ta, O, sputtering haze, and the process was otherwise the same as in this example, and the cell was made into MM.゛IJi
The flow density ratio was 5.5%, and the conversion efficiency ratio was 3.0%.

Example-2 First, prepare a pmcz single-knot conductor substrate with a thickness of 250 μm and a resistivity of 10 Ω in the two directions (100) shown in FIG. 8. First, 30% NaOH The aqueous solution was heated to 110°C and immersed for 5 minutes to etch the surface layer. Heat and etch for 55 minutes.7111
1. Heat the etching solution with /(-ner) while passing two Liebig condensers (2 bottles), and carefully control the etching solution (
Etching is carried out twice under certain conditions to form the next surface (= unevenness wf).

To stop etching and remove alkaline residue on the surface of the silicon wafer (2), immerse it in a hydrochloric acid water bath (21 minutes w4, then wash it with running water for 15 minutes, rinse with acetone W, and then dry. and the surface of the silicon wafer 421
Pyramid-shaped protrusions (2) of 2 μm are uniformly formed on the sides and height, indicating a decrease in reflectance. Next, P is deposited and diffused using 42 POC4 as a source. Deposition for b minutes at 850 υ. Drive-in for 60 minutes to form a silicon wafer surface (3) including convex portions (knee diffusion) with a joint of 0.5 μm thick. After removing the surface saponification layer from the second side, apply A7-Ag paste (ENGERU-) A-422F to the back side.
・・Product name) is printed and fired (to form a good surface electrode from the second side. Firing is performed for 30 seconds with 8301J, and the r layer penetrates through the male diffusion layer on the back side, and the electrode is removed from the silicon wafer. Next, a silicon nitride film (2) is applied to the surface using a plasma CVD method (2) to remove the
k form. Assemble the parallel plate valley connection lid [1 Niue 7a, base '4! The reaction gas was introduced by increasing the LK degree to 300°C, and the high JiI of 50KHz was 11tM.
I put in a W and deposited. For the reaction gas C, SL& and NH3 were used, and N was used as a carrier gas. A uniform silicon nitride film with low reflectivity was formed on the silicon surface.

As a result of the analysis, the presence of two elementary ions (aat-g) was confirmed in the membrane.

On the second silicon nitride film (Ninegaresist OMR-85)
Spin code (Tokyo Ohka, - product name). Buttering is then carried out using a photo-etching method consisting of light exposure and in-situ etching. After this, plating method 62 is used to remove the silicon nitride film in other pattern parts with hydrofluoric acid (resist After removal, the well-known nickel-free dispersion process is performed to form the two electrodes and complete the solar magnetic core.

The solar magnetic core obtained in this manner also exhibited properties equivalent to those of the above-mentioned example. In addition, the anti-reflection coating of the same structure was different from that of the conventional method using titanium oxide, for example, using the fish waste method. Compared to the case, the effect of hydrogen loading in the film ζ2) is reduced in the form of mechanical bonding, and especially in the light IIA in the short wavelength region (2).
The improvement in FIt was clearly demonstrated by spectral response measurement, which measures the photosensitivity spectrum when irradiated with monochromatic light. This indicates that it is advantageous for use in a solar room under a fireworks lamp in space, where there are many short-wavelength components due to the correction of sunlight.

Example-3 The fourth factor is an example using a polycrystalline silicon substrate (6) in which many crystal grain boundaries (4υ) exist. Specific resistance 1Ω・cML, 300 μm thickness of P1!i After thorough cleaning, an n+ diffusion layer was formed on the fi surface of the wafer. This birdcage was heated to 890°C using POCIm in a vapor phase to remove phosphorus. Deposition was carried out for 10 minutes, followed by 10 minutes of drive-in.A bond with a bonding depth of 0.3 μm was formed from the two substrates.
(Engelber) A-3484...dark name) printing and C2 type (firing), history l-Ag paste (
A base electrode was formed by printing and firing Engelbarthom 2734 (part name). The AA paste should be fired at 850°C for 15 seconds. The efficiency of the paste was fired at 700°C for 30 seconds to form a grid-like electrode.・Product name) was used to print with a 325 mesh stainless steel screen and baked at 650°C for 9 seconds. As a result of analysis, the presence of ionized hydrogen in the film and hydrogen bonded to the substrate was confirmed.

When diactivated hydrogen is introduced into the film from C Nigraz i during formation, dangling bonds and bonds are formed at grain boundaries. As a result, recombination of carriers at grain boundaries was reduced, and a large amount of photocurrent was obtained, resulting in the same efficiency. Figure 5 shows the improvement in photocurrent when an antireflection layer having a hydrogenation effect is formed by a well-known method of observing the distribution of photocurrent in a minute area while scanning a laser beam. (b) shows a case in which no antireflection film is formed, and the drop at the m6 grain boundary is large.On the other hand, (b) shows a case in which a plasma silicon nitride film is formed, and the drop at the grain boundary is small.

On the other hand, when a conventional anti-reflection film that does not contain hydrogen is formed, the shea (b) does not occur, and the curve is similar to (a), with an overall higher level than ta). As a result, in the non-example, an improvement in conversion efficiency ratio of about ions was given compared to the conventional one.

Example 4 Two different examples (two examples will be explained with reference to FIG. 5. First, orientation (100), thickness 2501 layer m e specific resistance 10 Ω・alO boron-7'FZ silicon monotih
Prepare a 6m harpoon. After thorough cleaning? Diffusion layer
A film was formed on the surface of a quencher. For this purpose, ion implantation was performed at a density of 2.5 x 10" ions/- at an acceleration energy of 10 KeV, followed by 1.
Seven cycles were performed at an intensity of 5 J/alIO. This made it possible to form a junction with a depth of about 0.2 μrno*. Next, a BSF layer was formed by implanting niboron ions on the back surface. BF was used as the boron source, and the acceleration energy and ion density were 25 KeV and 5 x 10, respectively.
“Io y/cd.

The back surface electrode and the front electrode were formed from N4 by continuous vaporization of titanium, platinum, and silver. Furthermore, there is an anti-reflection layer (T) on top of this.
was formed. A T&tOg film was selected as the anti-reflection film, and hydrogen was introduced into the film using a sputtering method (NiyoυTa, OB).
This was achieved by forming a film while injecting dihydrogen ions onto the substrate on which they are deposited (with a nitrogen ion gun).

The solar cell obtained in this way (-) also has the same characteristics as in the previous example.
Compared to conventional solar cells with antireflection layers that do not contain hydrogen, the conversion efficiency ratio was 2 to 3 times higher than that of conventional solar cells with antireflection layers.

Example-5 Fig. 186 shows an example in which silicon is used. 10cxx2octn (D f) with specific resistance of 1Ω and P fence thickness of 35G pm
y7'T! h;b. After the light-splitting situation went by,
A different surface (film was formed) on a wafer of n+Kanhuan J-IJ.For this reason, ≦2 was 900'0 using POCl3 in the vapor phase, and phosphorus was
A minute deposit was made, followed by a 10 minute drive-in. From this 42, a junction with a junction depth of α6 μmO was formed. Next (two surfaces (= after masking with resist,
j111! SiO was used for the anti-reflection coatings in which the nickel metal was deposited on the surface and kTlki, followed by silver electroplating to form the polar rings and the polar rings. While depositing SiO by the evaporation method, an anti-reflection film containing hydrogen was formed by injecting two elementary ions onto the substrate using an ion gun C. Dangling bonds at grain boundaries were inactivated. We were pleased with the improvement in efficiency from the solar and sunlight characteristics evaluation (second).

This will be explained with reference to Implementation Self-6 j171Gl. This example shows the direction (11
1) A boron-doped C2 single crystal wafer (71) with a thickness of 300 firm *specific resistance of 10Ω·α is prepared. It has a 4 inch diameter and has been polished on both sides. After cleaning, one layer (72) is formed on the substrate-photometric surface. By depositing phosphorus at 850°C using electricity for 15 minutes, and then performing a drive-in for (9) minutes, we deposited zero-order (= aluminum on the other side of the two substrates) and deposited BSF M by sintering. Next, excess aluminum and its oxides are removed using hydrofluoric acid and hydrogen.
Bring out the surface. Next, the front surface electrode (73), the back surface l1i
The iL electrode (74) is plated with silver paste and fired (= film formed).The anti-reflection film (75) is formed by plasma CVD method (first of all, a silicon nitride film is formed (2x'm)).
method (Niyoshi 1050 A L: DMgRM was layered. Hydrogen was introduced through the first layer of silicon nitride,
The second layer of MgFl film enhances the anti-reflection effect.In this way, when applying multiple layers of anti-reflection film,
The use of an antireflection layer incorporating double hydrogen is effective.

Solar cells prepared in this manner also exhibited good improved properties.

(Effects of the Invention) As described above, according to the present invention, since hydrogen is added during the formation of the antireflection film, the surface red bonding rate is reduced, making it possible to realize a highly efficient *O solar cell. In addition, due to improved short wavelength sensitivity, it is suitable not only for terrestrial use, but also for indoor and space applications (both
It can be applied to many fields, and it is possible to add a significant improvement effect to polycrystalline Wa-4, which is attracting attention as a low-cost material.

[Brief explanation of the drawing]

The 11th Q shows the structure of a conventional solar cell, and Figure 2 shows the structure of a conventional solar cell. Figure 34 and Figures 6 to 8 show one embodiment of the present invention, and Figure 85 is a characteristic diagram of a solar cell according to the present invention. 1υ, 0υ, ring...Circular conductor board ring, @, 41-...Diffusion layer (14), L9. Cl41. ffi, 14.
(fit・[&(2), tMJ, @-・Anti-reflective film (7317) Agent: Patent attorney Noriyuki Chika (and 1 others)
Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 8 Procedural amendment 1) (Voluntary) Commissioner of the Japan Patent Office Kazuo Wakasugi1, Patent Application No. 1983-28123 2. Name of the invention Solar cell and method for manufacturing the same Relationship with the case of the person making the amendment Patent applicant (307) Tokyo Shibaura Kouki Co., Ltd. 4, Agent Address: Tokyo Shibaura, 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100 Japan Sanki Co., Ltd. Tokyo ◆ Office (1) Claims column of the specification +21 1! Column for detailed explanation of the invention in the specification (3) Understanding the brief explanation of the drawings in the specification (4) Drawing In ・・・・・・・・・・・・, "The present invention relates to an anti-reflection film" is corrected to "The present invention relates to an anti-reflection film." (2) Specification No. 14N, line 8 5; certain r 100 m
W/, 7 J was corrected to r 100 mW/ cd J. (3) "Figure 5" in the 19th negative line 18th line of the specification
is corrected to "Figure 6". (4) Specification No. 19 Am Line 19 to No. 2111114
On the 19th line, ``First, the direction (100), the thickness 28
0μrn ・・・・・・・・・(omitted)・・・・・・
...This example shows the direction (November), [this example shows the direction (
111), corrected as J. (5) In the 23rd page of the specification, lines 11 to 13, "Fig. 2 is a characteristic diagram." is replaced with "Fig. 2. FIG. 5 is a characteristic diagram of a solar cell according to one embodiment of the present invention, and FIG. 6 is a diagram showing another embodiment of the present invention. ”
I am corrected. (6) The scope of claims is amended as shown in the attached sheet. (7) Among the drawings, Figure 6 and cause 7 will be deleted, and Figure 8 will be corrected as shown in the attached sheet. Claims H (1) Claims that include a semiconductor substrate having a bond and a ve mold based on this semiconductor! The solar cell according to item II & 1. (3) The solar cell according to claim 1, wherein the semiconductor substrate is a V9 semiconductor substrate. (4) The solar cell according to claim 3, wherein the V-refun substrate is a polycrystalline silicon substrate. A solar cell according to claim 1. (6) The solar cell according to claim 1, wherein the V recon board is of P type. A method for manufacturing a solar cell in which nitridation is performed by a sputtering method containing hydrogen in the gas. Ending diagram

Claims (1)

[Scope of Claims] (1) A thick magnetic field comprising a semiconductor substrate having a junction and an anti-reflection film formed on the semiconductor substrate, wherein the anti-reflection film includes a at least one of the antireflection film and the semiconductor substrate near the boundary box 4;
, hydrogen in the ionic foreground, or hydrogen in a state bonded to the NII recording plate. (2) The solar cell according to claim 1, wherein the W value is that the anti-reflection film is made of silicon monoxide. (3) The solar cell according to claim 81, wherein the semiconductor substrate is a silicon substrate. (4) The solar cell according to Paragraph 3 of Patent No. 8, characterized in that the silicon is polycrystalline silicon. (5) It is noted that mt2 on the side of the semiconductor substrate on which the antireflection film is formed has an anisotropically etched surface.
41L thick It battery according to claim 1. (61/Solar cell according to claim 1, characterized in that the recon board is made of P. A solar cell according to claim 1. (8) On a semiconductor substrate having a base 42, the sputtering gas contains hydrogen or a metal hydride! (9) On a semiconductor substrate having a junction (2. In a reactive gas (2. A solar cell manufacturing method patented in which the first root forming the protective film is A-biased.