JPH06188207A - Formation of semiconductor coating film - Google Patents

Abstract

PURPOSE:To lower the recombination central density thereby enabling the mobility of electrons or holes in a film to be enhanced by a method wherein the film of silicon or silicide is formed on a substrate using a reactive gas having silicide and then the film is photo-annealed by irradiating it with intensive laser beams to crystallize the film for neutrallizing any unpaired bonds by activating hydrogen. CONSTITUTION:A reactor 3 containing a boat 2 fitted with substrates 1 is evacuated with a vacuum pump. Besides, a vessel 7' is impressed with high-frequency energy 10 besides, required amount of silicide 14 becoming a reactive gas is led into the reactor 3 to form a semiconductor film on the substrate 1. Next, this semiconductor film is laser beam annealed so as to change non-single crystal semiconductor into single crystal semiconductor. Furthermore, hydrogen is activated by high-frequency inductive energy to make the single-crystal semiconductor couple with any unpaired bonds for neutrallization. Through these procedures, the recombination central density is to be lowered thereby enabling the mobility of the electrons or holes in the film to be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method for forming a semiconductor or a semiconductor film on a substrate by a vapor phase method. The present invention forms a coating film containing silicon as a main component on a semiconductor and then fills the coating film with hydrogen in an active state together with helium or neon so that inductive energy (here, high frequency or microwave energy is simply induced). (Referred to as energy), a substrate having a semiconductor film formed thereon is immersed in a hydrogen or helium atmosphere in a chemically active state.

[0002]

2. Description of the Related Art Conventionally, a vapor phase method, especially a reduced pressure vapor phase method, is known when a silicon film is to be formed when a film containing silicon as a main component. This reduced pressure vapor phase method is related to the application of the present applicant and is described in Japanese Patent Publication No. 51-1389. However, this depressurized vapor phase method is intended to form a film having a uniform film thickness on a large number of large-area substrates, and a silicide gas, particularly silane, of 0.1 torr to 10 torr
It is intended to be formed on the substrate by thermal decomposition in the reduced pressure state of 600 ° C. The temperature required for forming the film is 600 ° C to 800 ° C.
It was a high temperature of ℃. This high-temperature treatment is acceptable when the substrate is a heat-resistant ceramic material such as silicon oxide or silicon nitride, which is a compound of semiconductor silicon or silicon.

However, when a substrate having an organic substance such as epoxy or glass or a thermal expansion coefficient to some extent and having a large size and being easily broken (for example, glass), or a substrate obtained by coating a conductive film on this substrate is used. Was a huge drawback. On the other hand, the glow discharge method is known as a method in which the film-forming temperature is from room temperature to low temperature of 300 ° C, but the film formed on only one substrate has an extremely non-uniform film thickness. Has been. This is a substrate of about 2 cm square or about 3 cm diameter 0.01 torr or
Activate the silicide gas by immersing it in a reduced pressure atmosphere of 10 torr, especially 0.1 torr to 1 torr, introducing a silicide gas, especially silane, into this reaction furnace, and causing glow discharge in the vicinity of the substrate by an induction furnace. To form a film on the substrate.

However, in this case, since it is necessary to mix a large amount of hydrogen into the film, the carrier gas is 100% hydrogen, and the silane is also 100% or a gas diluted with hydrogen, nitrogen or argon gas. The method used is known. Further, as a method for forming a plurality of coating films on a substrate, there is, for example, "Method and apparatus for manufacturing semiconductor single crystal thin film" described in Japanese Patent Laid-Open No. 53-1465. The manufacturing method disclosed in the above publication comprises a first vapor phase growth chamber, a second vapor phase growth chamber, and a preliminary chamber, and a plurality of coatings are formed by sequentially arranging the substrate in the vapor phase growth chamber. It The above manufacturing method is excellent in productivity because the coating film can be continuously formed on the substrate. In addition, a "sample transfer device in a vacuum device" for forming a plurality of vapor-deposited films by a series of vacuum chambers is disclosed in Japanese Utility Model Laid-Open Sho 53-1490
No. 49 publication. Further, a "semiconductor device" in which three layers of a P layer, an I layer and an N layer are formed on a substrate by plasma CVD is disclosed in, for example, Japanese Patent Publication No. 53-3771.
No. 8 publication.

[0005]

It is known that a non-single crystal semiconductor generally contains a large number of dangling bonds. For example, the recombination center density in a non-single crystal semiconductor is as high as 10 ²⁰ cm ^-3 to 10 ²² cm ^-3 . But,
In order to manufacture a semiconductor device using a non-single crystal semiconductor, the recombination center density is 10 ¹⁵ cm ⁻³ to 10 ¹⁶ cm.
Must be ^-3 .

The present invention is intended to solve the above problems, and an object of the present invention is to provide a method for producing a semiconductor film capable of reducing the density of recombination centers and improving the mobility. In addition, the present invention is capable of mass production and allows a substrate to form a uniform film on a large area of 10 cm to 20 cm, and the substrate temperature required for producing this film can be room temperature to 400 ° C. This is a major feature. Further, the present invention provides for chemical activation of the reactive gas, or reaction at a location remote from the substrate, and maintaining its active state by encapsulating the reactive gas with helium or neon and the helium. Further, it was experimentally found that neon uniformly forms a film on the surface on which the reactive gas is formed.

[0007]

In order to achieve the above-mentioned object, a method for producing a semiconductor film according to the present invention comprises a step of forming a film of silicon or a silicon compound on a substrate using a reactive gas containing a compound of silicon. And a step of crystallizing the film by irradiating it with strong light to perform crystallization, and a step of neutralizing dangling bonds by hydrogen. Further, in the method for producing a semiconductor coating film of the present invention, formation of the coating film is performed by applying induction energy.

[0008]

[Operation] In the first step, a reactive gas containing a compound of silicon is introduced to form a film of silicon or a silicon compound on the substrate. In the second step, the coating film formed in the first step is irradiated with, for example, laser light or strong light equivalent thereto. Then, the film is crystallized by performing optical annealing by the intense light. In the third step, hydrogen is introduced after the second step or almost simultaneously with the second step to neutralize dangling bonds existing in the film. Induction energy can also be added to the treatment of the above coating. As a result, the dangling bonds in the film were neutralized and the recombination center density was decreased, and the mobility of electrons or holes could be improved.

[0009]

[Examples] Examples will be described below with reference to the drawings. Example 1 A substrate is a conductor (stainless steel, titanium, titanium nitride, or other metal), a semiconductor (silicon, silicon carbide, germanium), an insulator (organic substance such as alumina, glass, epoxy, or polyimide resin), or a composite substrate ( An insulating substrate on which a transparent conductive film such as tin oxide or ITO was formed, and a P or N type semiconductor formed on the substrate in a single layer or multiple layers) were used. In all of the present invention as well as this embodiment, these are generically referred to as a substrate. Of course, this substrate may be flexible or a rigid plate. FIG. 1 shows an embodiment of a manufacturing apparatus for forming a semiconductor film of the present invention, particularly a silicon film. In FIG. 1, a substrate 1 is adjacent to a boat (for example, quartz) 2 on the boat 2. As the substrate 1, a 10 cm square having a thickness of 200 μm is used in this embodiment. The substrate 1 was enclosed in the reaction furnace 3. This reactor 3 has a frequency of 1 MHz to 100
The reactive gas and the substrate 1 can be excited, reacted or heated by the high frequency induction energy from the high frequency heating furnace 4 of MHz, for example, 13.6 MHz.

Further, a heating device 5 by resistance heating is installed on the outside thereof. Evacuation of the reaction furnace 3 is performed by a vacuum pump 8 from a portion indicated by reference numeral 6 through a valve 7. The reactive gas reaches the inlet indicated by reference numeral 9, but at a position away from the substrate 1, the high frequency induction energy 10, here 1 GHz to 10 GHz,
For example, it is chemically activated, decomposed or reacted by microwave energy of 2.46 GHz. In the part of the container 7 ′ where the high frequency induction energy 10 is applied,
A compound of silicon which is a reactive gas, such as silane (SiH
₄ ), dichlorosilane (SiH ₂ Cl ₂ ), and optionally P-type or N-type impurities, and / or germanium, tin, lead, or a reactive gas containing nitrogen or oxygen. Mixed.

In addition, in the present embodiment, helium or neon is 5% to 99%, particularly 40% to 90%.
It was mixed. Here, these reactive gases are chemically activated by the high frequency energy 10 and further partially react with each other. The reaction system (including container 7 ') is 10
^-3 torr to 10 ² torr, especially 0.01 torr to 5 to
It was rr. With respect to the chemical activity away from the surface to be formed, there is a method using a catalyst proposed by the applicant in the gas phase method. For example, there are JP-B-49-12033, JP-B-53-14518, JP-B-53-23667, and JP-B-51-1389. In this example,
The catalytic activation in the catalytic gas phase method is positively carried out by utilizing high frequency induction energy, whereby chemical activation or physical excitation is made more complete. The silicide gas 14 which is a reactive gas includes silane (SiH ₄ ), dichlorosilane (SiH ₂ Cl ₂ ),
Trichlorosilane (SiHCl ₃ ), silicon tetrachloride (S
iCl ₄ ), but silane was used because it is easy to handle. In terms of price, dichlorosilane is cheaper,
You may use this.

As the P-type impurity, boron is added to diborane 15 to a concentration of 10 ¹⁷ cm ⁻³ to 10 mol%, and as the N-type impurity, phosphorus (PH) is used.
₃ ) was adjusted to a concentration of 10 ¹⁷ cm ^-3 to 20 mol% and used. The P-type impurity may be arsine (AsH ₃ ). As the carrier gas 12, 5% to 30% of hydrogen was mixed with helium (He) or neon (Ne) or their inactive gas during the reaction, but low-cost nitrogen (N ) Was used with liquid nitrogen. Furthermore, for the additives tin (Sn), germanium (Ge), carbon (C), nitrogen (N), and lead (Pb), the hydrogen compound or chloride gas is introduced from the reference numeral 13 in FIG. To be done. When these reactants were liquid at around room temperature, the liquid was bubbled and vaporized by the helium and introduced into the reaction furnace 3 by the helium.

In the reaction system, oxygen and the like that first adhered to the inner wall of the container were removed by being heated to 800 to 1200 ° C. by the heating device 5. After that, the boat 2 having the substrate 1 attached thereto from the exhaust port side is put into the reaction furnace 3. After that, the container 3 is evacuated by a vacuum pump 8 to 10 ⁻³ to
It was up to rr. Further, for a while, helium or neon was introduced from the reference numeral 12 shown in FIG. 1 to purge the reaction system. Also, the container 7'has high-frequency energy 1
0 is applied, and the reactive gas is denoted by reference numeral 1 in FIG.
The required amount is introduced from 3, 14, 15, 16 and mixed thoroughly. Then, the mixed reactive gas was introduced into the reaction furnace 3. At this time, excitation or activation may be promoted by the high frequency induction energy 4 of 10 W to 300 W.

FIG. 2 is a diagram for explaining the characteristics of the coating film obtained in this example. In FIG. 2, the temperature (degree C) is shown on the X-axis, and the film growth rate is shown on the Y-axis. As is clear from FIG. 2, even if the reactive gas is separated from the surface to be formed by 10 cm to 3 m, for example, 1 m, the carrier gas is 5% to 99%, for example 70%, of the helium or neon, the coating film is Is formed as a curve 22. The uniformity of the coating film shown by the curve 22 was within ± 2% between the lots and within the lot when the formed film thickness was 5000Å. For reference, when the same amount of nitrogen was used as the carrier gas, the curve 23 shown in FIG. 2 was obtained and almost no film was formed.

In addition, 1 hydrogen (H ₂ ) is contained in the helium.
When 5% to 30% is added, the uniformity of the coating is ± 3%
It became worse by 4% to 4%. For the curve 22 of FIG. 2 showing the case of applying microwave energy away from the substrate 1,
Even when the high frequency induction energy 4 was added, the growth rate did not increase so much as the curve 21. The film formed when helium or neon is used as a carrier gas has a low temperature of room temperature to 400 ° C. and thus has a non-single crystal structure of a polycrystalline or amorphous structure. This non-single crystal structure is
It is generally known that there are many unpaired bonds. For example, in the device of the present embodiment, when the carrier gas is nitrogen, the density of recombination centers is as high as 10 ²⁰ cm ^-3 to 10 ²² cm ^-3 . However, when this carrier gas is helium or neon, these gases, especially helium, can move freely in the coating film, so that the dangling bonds are activated, and the effect of neutralizing them by covalent bonding with each other. there were. Therefore, the density of dangling bonds is 10 ¹⁷ cm
^-3 to 10 ¹⁹ cm ^-3 could be lowered.

However, also in this case, when it is intended to be used as a semiconductor, the density of dangling bonds is 10 ¹⁵ cm ^-3 to 10
Need to lower to ¹⁶ cm ^-3 . For this reason, in general film formation, a method is known in which hydrogen is activated as a carrier gas and the hydrogen is bonded to the dangling bonds to neutralize the hydrogen. However, when this hydrogen is used as a carrier gas instead of helium, the uniformity of the coating becomes extremely poor,
Under the same conditions as the device of FIG. 1, it became ± 8%. Therefore, in this example, the carrier gas was used to form a uniform film as helium or neon, and after this film was prepared, hydrogen, or hydrogen in the same reaction furnace or a different reaction furnace was used. Gas containing helium was chemically activated by high frequency induction energy. In the apparatus of FIG. 1, high frequency induction energy 4 was used.

At this time, the high frequency induction energy 4 is
It was preferable to orient the substrate 1 in a direction perpendicular to the substrate 1 to promote the injection / neutralization of hydrogen or helium into the substrate 1. Of course, the semiconductor layer is photo-annealed by laser or strong light energy similar to that (for example, a xenon lamp) to single crystallize the non-single crystal semiconductor. That is, promoting crystallization, preferably a single crystal, further,
After this single crystallization or at the same time as this photo-annealing, the neutralization with hydrogen and helium utilizing this high frequency induction energy is extremely effective. In particular, the carrier mobility is 10 to 100 times as high as that obtained by laser annealing.
It doubled, and became close to the ideal state of a single crystal. However, this single crystallization alone cannot bring the density of recrystallization centers to 10 ¹⁴ cm ^-3 to 10 ¹⁵ cm ^-3 ,
It stayed between 10 ¹⁸ cm ^-3 and 10 ¹⁹ cm ^-3 . Therefore, the induction energy annealing performed after or at the same time as the laser annealing has a great effect on producing an ideal single crystal semiconductor. As a result, it is possible to form a P-type or N-type semiconductor film as a single layer by using a PN junction or a PI.
N-junction, PNPN junction, PNPN ... PN junction could be freely made in multiple layers.

Therefore, the coating film produced by the method of this embodiment can be applied to a semiconductor laser, a light emitting element, or a photoelectric conversion element such as a solar cell. of course,
The method of this embodiment can be applied to a MIS field effect transistor, an integrated circuit or the like, and has great value. When the microwave of FIG. 1 is used, the energy of the microwave uses a magnetron or the like. However, since it is practically difficult to generate strong energy, activation in a position distant from the substrate 1 is suppressed in industrial production.
It may be performed using high frequency induction energy of MHz to 100 MHz. 0.5 m to 3 m, especially 1 m to 1.5 m of activation, excitation or reaction of the reactive gas by the high frequency induction energy at a position away from the substrate 1.
The pressure of the system is 0.01 torr or 10to
With rr, there was almost no decrease.

Embodiment 2 FIG. 3 shows another embodiment of the manufacturing apparatus for forming a semiconductor film of the present invention. The second embodiment will be described with reference to FIG. The film forming apparatus shown in FIG. 3 has a PN junction, a PIN junction, and a PNPN.
Junction, PNPN ... A PN junction or a Schottky junction having a MIS structure or the like for automatically and continuously forming multiple semiconductor layers of different conductivity type or same conductivity type on a semiconductor on a substrate. That is, a large number of large substrates are superposed on the front and back, and in order to form a uniform film on the object to be formed arranged in pairs, in this embodiment, a reactive gas is reacted or activated at a position distant from the substrate. And the reaction product or reactive gas in this reaction or active state is maintained in such a state that the ionization voltage such as helium or neon is high (24.19 e V, 2
1.59 eV) It is extremely important to carry the carrier gas.

In this apparatus, the substrates 31, 31 'placed on the boat from the inlet 30 side are moved to the container 45 by opening and closing the partition plate 44. In the embodiment of the present invention, the back surfaces of the two substrates 31 and 31 'are overlapped with each other to double the effective surface to be formed for the reaction products and to expand the effective amount of the reactive gas. Was halved. Thereafter, the reactive gas 40, 41, 42 already described in the first embodiment is applied to the valve 3 on the substrate 31, 31 '.
It is introduced into the excitation chamber 32 by opening and closing 8.
In the excitation chamber 32, the high frequency induction energy 33 chemically excites, activates or reacts the reactive gas and the carrier gas, and then is introduced into the container 45 via the homogenizer 34. The substrate 31 is introduced into the container 45, and if necessary, it is rotated at 3 to 30 revolutions per minute, for example, 6 revolutions / minute in the directions indicated by reference numerals 50 and 50 'in FIG. , Of the reactive gas introduction part 32
The unevenness of the film growth rate between the side and the exhaust portion 36 side is effectively removed to make the film uniform.

This rotation is for improving the uniformity of the formed film. Further, the substrates 31 and 31 ′ are reacted and excited by the high frequency induction energy 35. Then, unnecessary reaction products and carrier gas are exhausted from the vacuum pump 36. This exhaust gas 37 is then
Impurities and residuals of reaction products are removed by a filter and a trap, and a carrier gas such as helium is purified by a purifying device, and a closed loop is again introduced into 40 as a carrier gas. This means exhaust 37,3
The same applies to 7 ′, 37 ″, ... In the above manner, in the system 1, silicon having a predetermined thickness, for example, 10Å
To 10 μm of a silicon-based coating is formed,
In that case, impurities having I-type, P-type, or N-type conductivity are deposited on the substrate at the same time when the film is formed and are mixed into the film.

After the treatment of the system 1 was completed, the reactive gas and the reaction products in flight of this system were exhausted and eliminated. After that, the boat in which the substrate is planted is moved to the system 2. The pressures of the vessels of system 1 and system 2 during this movement must be the same. After that, also in the system 2, as in the system 1, a film containing silicon as a main component is formed according to the design. At this time, the substrate of system 2 is in system 3, the substrate of system 3 is in system 4,
The substrate of system 4 moves to the outlet 59. The respective systems 1 to 4 represent P-type film forming, I-type film forming (state in which impurities are not artificially mixed in), N-type film forming and induction annealing systems. However, if the junctions are to be made to PN, PI ₁ I ₂ N, PNPN, etc. junctions rather than PINs, with their faces approximately parallel to the substrate surface, then the number of systems is increased or decreased accordingly.

In the present embodiment, a coating film having the same stoichiometry is formed in parallel with the surface on which the substrate is formed, and the amount of impurities is Ge, Sn, Pb,
The amounts of additives such as N, O and C are also uniform in the surface direction. However, it is possible to control Eg (energy hand gap) by changing the amounts and types of In, Ge, C, N, and O in the direction in which the film is formed, which is also large in this embodiment. It is a feature. Further, in this case, the energy hand gap can be continuously changed by changing the amount of the additive by the valves 38 and 38 '. As described above, in the present embodiment, when silicon carbide is formed on the formation surface of the substrate, the reactive gas is chemically activated, excited or reacted at a position distant from the substrate, and at this distant position. , Silicon or impurities, additives were stoichiometrically well mixed. A film was formed so that a specific material was not present in the resulting film. This is also a feature of this embodiment.

In this embodiment, silicon is mainly used. However, by adding nitrogen to this silicon, Si ₃ N
_4- x (0 <x <4), Six with the addition of germanium
Ge ₁ -x (0 <x <1), Six Sn ₁ -x with tin added
(0 <x <1), and lead is added to Six Pb ₁ -x (0 <x <
1), it is said that a mixture such as SiO ₂ -x (0 <x <2) by adding oxygen and Six C ₁ -x (0 <x <1) by adding carbon may be prepared. There is no end. Also,
Depending on the value of these x, not only Si but also Ge, Sn
Etc. may be formed. It is also possible to mix P-type or N-type impurities into these semiconductors at the same time, and in particular, conductive impurities In and Zn are added in addition to B as P-type impurities, and N is added. In addition to P as a type impurity, Sb, Te, or S
e may be added to improve the activity of impurities.

In this example, the inert gas used as the carrier gas was limited to helium or neon.
The ionization voltage of Helium is 24.57 eV, that of neon is 21.59 eV, and Ar, Kr and N ₂ which are other inert gases are 10 eV to 15 eV, which are smaller than those of the two. As a result, this He or Ne maintains the ionized state for a long time, and its active energy is large. As a result, it is presumed that He or Ne causes the reaction product to form a uniform film on the surface to be formed, and also increases the substantial mean free path of the reactive gas. These were obtained from experimental facts, and in particular, Helium released a reactive gas when a semiconductor film was not uniformly formed on a large 10 cm to 30 cm square substrate like the apparatus of this embodiment. It has a major feature that a highly uniform coating can be obtained even if the chamber required for activation at a position is made small enough to be practically acceptable.

Furthermore, in this embodiment, the coating is
It mainly describes that it is a semiconductor. However, this film is also effective for forming a film for forming a single or multiple oxides or nitrides of tin, indium or antimony which constitute a semiconductor, especially a transparent electrode. At that time, those halides such as tin chloride (SnCl ₄ ), indium chloride (In ₂ Cl _3).
(H ₂ O) liquid is bubbled in a helium, and the vaporized and atomized reactive gas is chemically activated in a high frequency induction furnace, and is further formed as a film on the film surface at a position further away from it. You may. In particular, in the case of manufacturing one or both electrodes of a semiconductor device utilizing light such as a solar cell, it is transparent before the semiconductor layer is modified by this embodiment or after the semiconductor layer is formed by the method of this embodiment. It is possible to fabricate the electrode by continuously forming the conductive coating of (1) and (2) in this way, which enables an engineering-consistent flow operation of the electrode.

As the transparent conductive film, not an oxide but a nitride such as titanium nitride, tantalum nitride,
You may use tin nitride etc. At this time, titanium, tantalum, tin, or the like, which is a chloride, may be reacted with a nitride gas such as ammonia as a reactive gas. As a substrate,
GaAs, GaAlAs, B other than those described in Example 1
It goes without saying that it may be made of a compound semiconductor such as P or CdS. A photo-etching technique is used to selectively inject or diffuse P- or N-type impurities into the semiconductor or conductor film formed in the present embodiment, particularly the semiconductor film containing silicon as a main component, to partially form a PN junction. Further, if necessary, laser annealing may be partially performed to form a transistor, a diode, a visible light laser, a light emitting element or a light conversion element using this junction. In particular,
The energy band gap is set to W-N (WIDE TO
NALLOW) structure (W side is 2e to 3eV, N side is 1e to 1.5eV), PIN, MINPN junction, PNPN junction, MIPN junction type structure, and the transparent conductive electrode according to the present invention on the upper surface thereof. May be formed, and this may also serve as the effect of the antireflection film. By doing so, the photoelectric conversion rate can be improved to 15% to 30%, which is industrially useful.

[0028]

According to the present invention, the coating film formed on the substrate is irradiated with strong light to be annealed to be crystallized, and the density of recombination centers is reduced by hydrogen. We were able to improve the mobility of the hole.

[Brief description of drawings]

FIG. 1 is an embodiment of a manufacturing apparatus for forming a semiconductor film, particularly a silicon film, of the present invention.

FIG. 2 is a diagram for explaining the characteristics of the coating film obtained in this example.

FIG. 3 is another embodiment of the manufacturing apparatus for forming a semiconductor film of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Boat 3 ... Reactor 4 ... High frequency induction energy 5 ... Heating device 7 ... Valve 7 '... Container 10 ... High frequency induction energy 31, 31 "... Substrate 32, 32 ', 32" ... Excitation chamber 33 ... High frequency induction energy 34 ... Homogenizer 36, 36', 36 "... Vacuum pump 45, 45 ', 45" ... ·container

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 21/31 B 31/04

Claims (2)

[Claims] 1. A step of forming a film of silicon or a silicon compound on a substrate using a reactive gas containing a compound of silicon, and a step of irradiating the film with strong light to perform optical annealing to crystallize the film. And a step of neutralizing dangling bonds by hydrogen. 2. The method for producing a semiconductor film according to claim 1, wherein formation of the film is performed by applying induction energy.