JP3513572B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention
Using ultra-high purity semiconductor manufacturing gas
The present invention relates to a semiconductor device having at least one junction. [0002] 2. Description of the Related Art Conventionally, oxygen is a semiconductor such as a silicon semiconductor.
Constructs Si-O-Si locally in the body and shows insulation only
I was supposed to. However, oxygen is several to ten in silicon.
When a cluster is formed by gathering several pieces, it becomes electrons and holes.
Creates recombination centers and generates minority carriers generated by light irradiation.
Acting as a recombination center or killer
Is the plasma gas phase to which hydrogen or halogen element is added
Is very visible in non-single-crystal semiconductors
Turned out to be authoritative. [0003] Further, the dangling bond of oxygen is an N-type donor cell.
The non-single-crystal semiconductor
Structurally sensitive semi-amorphous with lattice strain rather than fas
(Semi-crystalline) turns out to be N-type.
Was. For this reason, oxygen that becomes such a donor center is essentially
To a structurally sensitive intrinsic (Fermirebe)
It is an industry to make semiconductors that have
It was extremely important when considering the practical application. Further, regarding carbon, CmHn (m
In the case of ≧ 2), it is mixed into the semiconductor as it is and recombined.
Many centers are generated and carriers, especially holes
This has led to a decrease in if-time. [0005] SUMMARY OF THE INVENTION The present invention is directed to a substrate or
A first electrode on the substrate and at least a PIN junction on the electrode;
A non-single-crystal semiconductor layer having one P-type semiconductor layer,
Provided by stacking a semiconductor layer and an N-type semiconductor layer
Photovoltaic devices in photovoltaic devices
Intrinsic or practically intrinsic intrinsic semiconductor layer
(1 × 10¹⁴~ 5 × 10¹⁷cm^-3No
Artificially mixed or background level
Especially for semiconductors).
Average concentration of oxygen or carbon which causes the generation of recombination centers
At 5 × 10¹⁸cm^-3Less preferably 1 × 10¹⁸cm^-3Less than
It is intended to make the concentration extremely low. [0006] SUMMARY OF THE INVENTION The present invention provides a method for removing such impurities.
Removed, and the silicon semiconductor is used to neutralize silicon and recombination centers.
Essential hydrogen or fluorine as the main component
III- or V-valent impurities to shift the
(Ten¹⁴~ 3 × 10¹⁷cm^-3) Characterized by added
You. Conventional silane has an effective molecular diameter of less than 5 mm (4.8 to 5 mm)
And Germanic has about 6 °. (Polysilane
Etc. have a larger effective molecular diameter)
Smell of silane (monosilane) with the smallest effective molecular diameter
When examining the impurities contained in the reactive gas,
As shown in Table 1 below. [0007] [Table 1] [0008] Investigation of these, especially this epitaxy
When growing, the oxide and
Due to the segregation effect, the nitride is as small as about 1/30 of Table 1 above.
It becomes. As a result, the intrinsic half of the specific resistance of 100 Ωcm or more
A conductor can be obtained. But done at 100-400 ° C
In the plasma gas phase method using glow discharge,
Expecting the effect of segregation of impurities, which is such physical refining,
Can not. For this reason, the impurities shown in Table 1
Will be mixed into the body, especially for oxygen and water,
All react with silane to produce reaction product silicon oxide.
For example, a 99.99% epitaxial gas was used.
In this case, 0.01% of impurities are mixed. To the silane itself
As for activation (ionization) by plasma reaction, 1
~ 5%, and thus substantially more than the gaseous state
About 20 to 30 times concentrated and 2 to 4 × 10²⁰cm^-3
It was found that the concentration was increased and the mixture was found. this
Therefore, when using a reactive gas for the plasma gas phase method,
It is very important to purify in the reactor.
It turned out experimentally. Thus, in the present invention, the change in AM1 is performed.
In order to guarantee a conversion efficiency of 10% or more, oxygen is contained in the I layer.
5 × 10¹⁸cm^-3The following, and the charcoal mixed in clusters
4 × 10¹⁸cm^-3Less preferably 1 × 10¹⁸cm
^-3It is very important that: Such semiconductor
It is an object of the present invention to increase the purity. The present invention provides a semiconductor device for such a purpose.
Reactive gases such as silane and polysila, which are silicide gases
, Silicon fluoride, and gel, which is a germanium gas
Make sure that its effective molecular diameter is at least 4.8 mm.
It was used. That is, when the effective hole diameter is 2.9 to 4.65 mm
4.5 using molecular sheep or zeolite
不 A fiber with an effective molecular diameter of less than or equal to
Pure oxide gas such as water (H_TwoO), carbon dioxide
(CO_Two), Oxygen (O_Two) And also carbide gases such as meta
(CH_Four), Ethane (C_TwoH₆), Propane (C_ThreeH₈), CH_ThreeOH
 , C₆H₆  The purpose is to adsorb and remove the like. In order to further promote the adsorption power,
Room temperature to -100 ° C, preferably -20 to -7
Cool to 0 ° C and increase the adsorption power more than 50 times.
And for the purpose. Thus, a non-
AM1 (100mW /
cm^Two), Only a conversion efficiency of 6 to 8% was obtained.
Things can increase the intrinsic conversion efficiency to 11-14.5%
did it. In particular, in the I layer which is the active semiconductor layer,
The oxygen concentration of the conventional 2-4 × 10²⁰cm^-35 × 10
¹⁸cm^-3Less preferably 1 × 10¹⁸~ 1 × 10¹⁴cm^-3Down to
In addition, the semiconductor further has a large number of CC bonds, that is,
4 × 10 carbon mixed in clusters¹⁸cm^-3Less preferred
Is 1 × 10¹⁸~ 1 × 10¹⁴cm^-3By lowering to
The density of recombination centers in a conductor such as a silicon semiconductor is 1 ×
Ten¹⁸cm^-31 × 10¹⁷cm^-3Less than 5 × 10¹⁴~ 1
× 10¹⁶cm^-3Successfully, and by light irradiation
The so-called Stebra-Lonski effect, in which photoconductivity deteriorates
It is characterized by being removed. The following is shown according to the drawings. FIG. 1 shows the present invention.
An outline of a manufacturing apparatus used for manufacturing a semiconductor device will be described.
As shown in FIG. 1, the reactor (1) (diameter 35 mmφ)
External heating furnace (21), substrate (22), a pair of electrodes (3),
 (3 '), high frequency oscillator (2) (e.g. 13.56MHz or 100K
Hz), and 1G to activate and decompose reactive gases
Microwave of frequency above Hz, for example 2.45GHz microwave
It has a wave oscillator (17) and an attenuator (18)
You. 0.00 from the discharge section protected by ceramics (19)
Microwaves are emitted to the reactor (1) held at 1 to 10 torr.
Let out. The whole reactor is shielded so that there is no radio interference
(20) is made and semi-conductive on the substrate (22) by reactive gas
When forming a body film, the electric field of electric energy
It is arranged so as to have a laminar flow parallel to the surface. The reactive gas is a carrier gas such as oxygen and water.
Hydrogen reduced to 1ppb or less, preferably to 0.1ppb
Was introduced from (7). Also, let's form a silicon film
In this case, silane, which is a silicide gas, is introduced from (4).
did. In addition, 500 to 5000
Diborane diluted in PPM is also converted to hydrogen from (5)
Phosphine diluted to 500-5000PPM (6)
Introduced. These reactive gases are supplied to a gas purifier (11), (1)
4), (12), (15), (13), (16)
Let me enter. These gas purifiers are located on the inlet side of the reaction gas.
3mm, 4mm, or 4.5mm with an effective hole diameter of 2.7 to 4.65mm
For example, 4cm effective hole diameter 3.5 ~ 4.3mm molecular sheeps
Or denatured using zeolite. This molecular
Sheep or zeolite is Na (AlO_Two) (SiO_Two) 27-30
H_Two O indicates 4 °, and 4.5 ° indicates (K_FourZn_Four) (AlO_Two) (SiO
_Two) 27〜30H_TwoThe one represented by the molecular formula of 〓O was used. Sa
After this, gas-lean for deoxidation (trade name GC-RX)
Was linked. These were both made by Nikka Seiko. Further, the chemical adsorption of these purifiers is improved.
To a temperature of -70 ° C to room temperature, for example, -30 ° C.
It cooled by (8), (9), and (10). Hydrogen-diluted Fosshi
Has an effective molecular diameter of about 4.3 mm.
Therefore, 3% or 4% was used. Also silane or disila
3Å, 4Å and 4.5Å are applicable
Noh. Especially for silane, N
In addition to oxygen, which is an easily converted impurity,
Reduce the concentration to 0.01ppb or less (5 × 10¹⁴cm^-3Below)
Therefore, it was particularly effective to use 4.5 mm. Exhaust system
Is the needle valve (25), stop valve (24), vacuum pump
The air was exhausted (26) through the pump (23). The pressure inside the reactor is
0.001 to 10 torr typically depending on the needle valve (25)
Controlled between 05 and 0.1 torr. FIG. 2 shows the characteristics obtained from the results of FIG.
is there. That is, the substrate temperature is 250 ° C and the pressure in the reactor is 0.1 torr.
When a non-single-crystal semiconductor layer is formed on a substrate such as glass,
Light irradiation (AM1) conductivity, dark when formed to a thickness of μm
Conductivity. In FIG. 2, such purification for silane
If not performed, impurities in the cylinder as described above
As it enters the semiconductor layer, oxygen or carbon is
This has the effect of making the capacitor amorphous. Therefore, the photoconductivity curve (29), the dark conductivity
The curve (30) was obtained. That is, the height of 20-30 W in the drawing
At frequency output, photoconductivity is 10^-3(Ωcm)^-1Order
But at this time the semiconductor has some order
It becomes semi-amorphous. Therefore, it is an impurity in this semiconductor.
Oxygen becomes a donor center, becomes N-type, and has a dark conductivity (3
0) also 10^-Four(Ωcm)^-1Of the order. Results and
If you use it as an intrinsic semiconductor,
1 to 3 × 10¹⁷cm^-3To the concentration of
Or a low output of 1-5 W. I
However, these are all evident from curve (29).
Again, light conductivity of 10^-6~Ten^-Five(Ωcm)^-1On the order
Lower it. Instead of such a conventional method, the present invention
Purifies impurities in the gas, especially oxygen, water or hydrocarbons (Fig. 1
(11) (14))
Also, when filling with sufficient purification
It is. Thus, oxygen containing water is purified and removed.
As a result, the light irradiation conductivity (27) as shown in FIG.
Degree (28) could be obtained. As apparent from FIG. 2, the photoconductivity is
The plasma discharge output is low
In the area, 10^-Four(Ωcm)^-1Greater than above, plus dark
Conductivity 10^-11~Ten^-Ten(Ωcm)^-1And small. That is, the intrinsic
The active energy as a semiconductor is large enough,
Bell is almost Eg / 2^+0.1 _-0.2can have eV
Was. Further investigation of this characteristic showed that the X-ray diffraction image
Weak crystallization at 5 to 10 W
These are observed in amorphous and crystallized structures.
Semi-amorphous semiconductor with intermediate structure
Was something. That is, an intrinsic semiconductor is formed by a plasma gas phase method.
If you try to obtain at 100-300 ° C, for example 250 ° C,
Impurities in silane are simply CVD or epitaxial
It is easy to enter a concentration 30 to 100 times that of growth. That
Minimize the contamination of starting materials with impurities
It is very important to use ultra-high purity silane.
Thus, even at a low output of 2 to 10 W, the dark conductivity is small.
And the photoconductivity is 10^-2(Ωcm)^-1Close to 10
^-Four~Ten^-3(Ωcm)^-1Was obtained. What can be obtained especially with such a low high-frequency output
Is to gradually form a PIN junction into a P layer, an I layer, and an N layer as in the present invention.
When laminating, define the boundary area as a plane.
That is, when laminating the I layer on the P layer, the P layer of the discharge is
Hit the underlying P layer due to the effect of spatter (damage) and mix
Preventing layers from forming at the interface PI interface
Is very important. Further, in the reactor shown in FIG.
Microwaves increase the ionization rate of reactive gases.
The characteristics were similar, but the film growth rate
Increased about 3 to 5 times and could be increased. For example
Introducing silane at 30cc / min at 0.1torr, high frequency plasma
Was only 1-3Å / sec, but in this case it was 10-15
高速 / sec. FIG. 3 relates to the purification of the silane of the present invention,
An experiment was conducted to confirm the effectiveness of the purifier. FIG.
In the graph, the horizontal axis indicates the concentration of oxygen or carbon in the coating.
FTIR (Fourier transform infrared absorption spectroscopy)
The vertical axis is the electrical conduction during light irradiation.
Indicates the degree. 1x10 more¹⁹cm^-3For the following impurity concentrations
Is measured using SIMS (3F type manufactured by Kameka).
Was. The absolute amount is corrected by ion implantation into amorphous silicon.
Depending on the specific injection volume (eg 1 × 10¹⁸cm^-3)
This was measured by SIMS and performed based on the ionic strength. Deoxygenation purifier (14), zeolite
When (11) is used together, curves (45) and (46) are obtained.
You. Curve (45) shows a carbon concentration of 3 × 10²⁰cm^-3When mixed
When oxygen concentration at the time of deoxygenation was used as a parameter
The curve (46) shows the oxygen concentration of 1 × 10²⁰cm
^-3(60), 3 × 10²⁰cm^-3(61) If mixed, conductivity
Ten^-Five~Ten^-6(Ωcm)^-1Especially when oxygen is mixed in
It can be seen that this is a factor that causes the degree to decrease. Still referring to FIG. 3, curves (41) and (42)
Oxygen concentration 3 × 10¹⁷cm^-3, Carbon concentration is 4 × 10¹⁸cm^-3Contains
The carbon concentration and the oxygen concentration are
It is shown as a meter. That is, especially oxygen is 5 × 10¹⁸cm^-3
By setting (43) below, the photoconductivity becomes 10^-3(Ω
cm)^-1And dark conductivity of 10^-Ten(Ωcm)^-1No
Can expect. Substrate temperature from 250 ° C
When the temperature is lowered to 200 ° C and 150 ° C, the conductivity becomes about 1/3 each.
Got lower. To obtain the oxygen and carbon concentrations,
It is extremely important to keep the oxygen (water) in
It is important that purification is not performed at room temperature,
Then, the oxygen impurity concentration is up to 0.01PPM and 0.003PPM.
Can be lowered. Also, pull out the exhaust system using a cryopump.
To reduce the residual water in the reactor to 0.1 PPM or less (10
^-8(The ultimate vacuum degree is torr or less.)
Prevented scattering. As a result, CmHn is reduced below 0.1 PPM
I was able to. Furthermore, starting silane (also called raw silane)
If liquefied and vaporized silane is used as
It cannot be measured at all with a mass spectrometer. Also formed
The concentration of oxygen and carbon in the semiconductor layer was 5 × 10¹⁶,
4 × 10¹⁷cm^-3Below and exceeding the detection limit of SIMS
Was completed. Of course, to achieve higher purity
In the reaction system shown in 1, the entire system including the reactor
Leak amount is 1 × 10^-Tencc / sec or less, preferably 1 ×
Ten ^-12cc / sec or less is important.
It is also important to note that the invention is important. FIG. 4 shows a structure formed by using the manufacturing apparatus shown in FIG.
Therefore, FIG. 4A shows a transparent conductive film (3) on a glass substrate (32).
3) and P-type silicon carbide (Si_xC_1-x  0 <x <1) (for example
If x = 0.8) or P-type silicon semiconductor (34), 100）
It was formed in thickness. After this, the reaction system is
Pump (62) is sufficient (10^-8torr below)
Then, the intrinsic semiconductor layer is formed to a thickness of 0.5 μm with the purified silane.
It was formed as (31). Evacuate it again
N-type semiconductor layer (35)_xC
_1-x x = 0.9, and mix phosphine to a concentration of 1%.
Into a thickness of 200 mm. After this the reflective electrode
If known silver or aluminum (36) is vacuum-deposited
It is provided. The high frequency output was 5 W and the substrate temperature was 200 ° C.
As a result, a conversion efficiency of 10.3% was obtained. This glass
To further improve the characteristics of the substrate, FIG.
A PIN junction type photoelectric conversion device having such a structure was fabricated. FIG.
(B), a P-type semiconductor on a stainless steel substrate (32)
Layer (34), I-type semiconductor layer (33), multi-layer having an N-type fiber structure.
The crystal semiconductor layers (35) are each 200
Å, 0.5 μm, 150 mm thick. Further transparent conductive film
(43) ITO (indium oxide [tin oxide 0-10
%]) Is vacuum-deposited, and aluminum auxiliary electrode (36)
Was provided. In the structure of FIG. 4B, the intrinsic half
The photoelectric conversion using the oxygen concentration mixed in the conductor layer as a parameter
FIG. 5 shows the conversion efficiency characteristics of the converter. Oxygen concentration is 5 ×
Ten¹⁸cm^-3Especially 1 × 10¹⁸cm^-3When it becomes
Efficiency (49) is 1cm with AM1^TwoOver 12% in area
I was able to. The fill factor (48) also exceeds 0.7
And especially short circuit current (47) up to 20mA / cm^TwoGet
Now you can do it. The open circuit voltage is 0.86 ~ 0.93V
there were. After all, the oxygen concentration becomes smaller,
Significant improvement in characteristics can be seen by making it like silicon
Was. In the embodiment shown in FIG. 4B, the N-type semiconductor layer is made of a fiber.
A polycrystalline semiconductor having a structure,
Patents filed by the inventor for making at low temperatures
Requested No. 57-078001 (57.5.24). FIGS. 6 and 7 show the reliability of the photoelectric conversion device.
And evaluated the extremely important reliability characteristics when
is there. FIG. 6 shows that the sample was added to the sample when measuring the constant energy spectral characteristics.
1 × 10 photons¹⁵/cm^TwoCurve (50)
You. The vertical axis represents the quantum efficiency (efficiency) normalized to the maximum point of “1”.
Indicated. AM1 (100mW / cm^Two) For 2 hours
Shoot. Subsequent light sensitivity changes as shown by curve (51)
However, its characteristics are extremely deteriorated for light of 350 to 500 nm.
It turned out to be lower. 2 hours at 150 ° C
When thermal annealing is added, the curve becomes (52),
For short-wavelength light between 350 and 500 nm, the curve (50) recovers,
Long wavelength light of 600-800 nm is not recovered. From this
Such light irradiation and thermal annealing do not cause deterioration,
Highly reliable photoelectric conversion device without Tebra-Lonski effect
Was sought. FIG. 7 shows that the average oxygen concentration in the I-type semiconductor is 5%.
× 10¹⁸cm^-35 shows the characteristics of the photoelectric conversion device in the case of. In FIG.
Perform light irradiation (AM1) for 2 hours according to the curve (50) shown.
On the contrary, a curve (51) with improved characteristics was obtained. Sa
Curve (52) slightly changed after thermal annealing
It was only. As a result, the defects in the I-type semiconductor layer
Extremely stable characteristics of oxygen (pure
Has been found to be important for Plus its oxygen concentration
At least 5 × 10¹⁸cm^-3Very low degradation in
Turned out not to be. Furthermore, this light irradiation effect (step
・ Lonski effect) reduces the oxygen concentration even further.
As a result, higher reliability could be obtained. In addition
As is clear from Fig. 5, conversion efficiency (curve (49)) is improved.
I do. This is due to the dangling bond of oxygen in the I-type semiconductor layer.
Decreases bonding centers, increases diffusion length of holes, depletes
Oxygen concentration is 1 × 10²⁰cm^-3Only 0.1 μm
The thing is 5 × 10 ¹⁸cm^-3Or less than 0.4 μm
And most preferably a field divided into the entire thickness of the I-type semiconductor.
If the photoelectric conversion device does not show any deterioration
it can. As described above, the present invention provides oxygen and carbon concentration characteristics.
The less oxygen as impurities, the more photoelectric
Improved conversion efficiency and reliability as a conversion device
That the practical oxygen impurity is 5 × 10¹⁸
cm^-3Less preferably 1 × 10¹⁸cm^-3Find that
It's nothing. In the above description, one PIN junction is
The photoelectric conversion device which has
..Primary joining and at least two joining
It is important for the application of
May be integrated on a substrate. Also, the explanation so far
Shows silane, especially monosilane, as silicide gas
did. However, the present invention is also applicable to polysilanes such as disilane.
Is effective, and physical purification of silicide gas
Larger particle size allows them to be applied
It is. The same applies to silicon fluoride such as SiF.
This is effective because its molecular diameter is as large as 5 °. Again
As for the rumanum, Germanic (GeH_Four)
Si as single crystal semiconductor_xGe_1-x(0 <x <1) or only Ge
It can also be used for the I-type semiconductor layer of the PIN junction.
You. In the above description, one PIN junction is provided.
The photoelectric conversion device described above has been mainly described. But semiconductor
The layer has at least one NI or PI junction, ie N (so
Source or drain) I (channel formation region) N (drain
In or source), insulated gate type with PIP junction
Field effect semiconductor devices or transistors with NIPIN or PINIP junctions
The present invention is very effective also for a transistor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an outline of a plasma gas phase reactor for manufacturing a semiconductor device of the present invention. FIG. 2 shows characteristics obtained by the present invention and electric characteristics of a conventional intrinsic semiconductor. FIG. 3 shows changes in electrical characteristics obtained by the reactive gas purification method of the present invention. FIG. 4 shows a photoelectric conversion device of the present invention. FIG. 5 shows various characteristics of the photoelectric conversion device obtained according to FIG. 4 (B). FIG. 6 shows constant energy spectral characteristics of a conventional photoelectric conversion device. FIG. 7 shows constant energy spectral characteristics of the photoelectric conversion device of the present invention. [Description of Signs] 1. Reactor 2. High-frequency oscillator 3, 3 'Electrode 8, 9, 10 Electrostatic chamber 11, 14, 12
Gas purifier 15, 13, 16 Gas purifier 17, Microwave oscillator 18, Attenuator 19, Ceramics 20, Shield 21, External heating furnace 22, Substrate 23, Vacuum pump 24・ Stop valve 25 ・ ・ Needle valve

Claims (1)

(57) [Claims] Intrinsic or substantially intrinsic non-single-crystal Si _x Ge
_1-X (0 <X <1), wherein the non-single-crystal Six _{x 1-X}
The oxygen concentration in (0 <X <1) is 5 × 10 ¹⁸ cm ⁻³ or less,
A semiconductor device having a carbon concentration of 4 × 10 ¹⁸ cm ⁻³ or less. 2. The substantially intrinsic non-single-crystal Si _x Ge _1-x (0 <X
<1) is the case where the impurity for P-type or the impurity for N-type is 5 × 10
^2. The semiconductor device according to claim 1, wherein said semiconductor device is added to a concentration of ^{14 to} 5 * 10 < ¹⁷ > cm < ^-3 >. 3. 3. The semiconductor device according to claim 2, wherein said P-type impurity is boron, and said N-type impurity is phosphorus. 4. The semiconductor device, the intrinsic or substantially intrinsic non-single-crystal _{Si x Ge 1-X (0} <X <1) and P-type Si _x Ge
_{1-X (0 <X <} 1) or N-type _{Si x Ge 1-X (0} <X <
According to 1), PIN junction, NI junction, PI junction, PI junction
4. The semiconductor device according to claim 1, comprising a P junction or a NIN junction. 5. The semiconductor device according to claim 1, 2, 3, or 4, wherein the semiconductor device is a photoelectric conversion device. 6. 5. The semiconductor device according to claim 1, wherein said semiconductor device is an insulated gate field effect semiconductor device.