JPH01766A - semiconductor equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device such as a field effect transistor, and more particularly to a semiconductor device whose main portion is composed of a polycrystalline silicon thin film semiconductor layer.

[Prior art and its problems] Recently, scanning circuits of image reading devices such as elongated one-dimensional food sensors and large-area two-dimensional photosensors, or liquid crystal (hereinafter referred to as LC) and electroluminescent ( Below E
With the increasing size of the drive circuit portion of image display devices that utilize electrochromic materials (hereinafter referred to as L) and electrochromic materials (hereinafter referred to as EC), these materials are being formed using silicon thin films formed on predetermined substrates. is proposed. As silicon thin films, hydrogenated silicon amorphous thin films and polycrystalline silicon thin films are being investigated. However, while the effective carrier mobility (hereinafter referred to as μoff) required by the scanning circuit of a high-speed, high-performance reading device and the drive circuit of an image display device is approximately 50 to 1000 cm”/V・SeC, In a crystalline silicon thin film, μeff is approximately 0.1c.
rr? /V-sec, which is not necessarily suitable for constructing the circuit section. On the other hand, polycrystalline silicon I&[ has a smaller μaf than that of amorphous silicon thin film.
Although 'f' was large, it was still insufficient, and there were drawbacks such as the inability to obtain a uniform film over a large area.

The cause of the above-mentioned defects in polycrystalline silicon is the existence of a defect level density of approximately 1018 cm'' at grain boundaries, and the presence of such defects causes the following problems.

Defect levels at the 0-grain boundary inhibit channel formation, resulting in a higher threshold voltage.

(2) In addition, defect levels and potential barriers at grain boundaries inhibit carrier transport and reduce the field effect strength.

Conventionally, in order to reduce the density of defect levels at grain boundaries, methods such as hydrogen plasma treatment and annealing using lasers, electron beams, etc. to enlarge the crystal grain size and reduce the number of grain boundaries have been tried. (IEEE ELECTRON
DEVICE LETTER5, VOL, EDL-1
゜No, 8. P, 159. AUGLIST, 19
80 T, 1. KAMINSetc,).

However, it is difficult to sufficiently reduce the density of defect levels at grain boundaries by hydrogen plasma treatment alone. Furthermore, it is difficult to sufficiently reduce the distortion of interface states even by laser annealing, and in particular, when forming a thin film transistor over a large area, it is difficult to make its characteristics uniform.

On the other hand, a method has also been proposed in which different radicals are brought together and reacted in a gas phase to deposit polycrystalline silicon on a substrate kept at a relatively low temperature (Japanese Patent Laid-Open No. 40717/1983).
. With this method, it is possible to incorporate an appropriate amount of hydrogen into the film in parallel with the deposition, and defects at grain boundaries can be uniformly compensated for by hydrogen.

However, hydrogen in the film also increases stress in the film, and may peel off during the film formation process or during the formation process of a thin film transistor.

The present invention has been made based on the above circumstances, and an object thereof is to provide a semiconductor device in which a semiconductor layer made of polycrystalline silicon has sufficient electrical characteristics and adhesion. be.

[Means for Solving the Problems] The present invention provides a semiconductor device that includes a semiconductor layer made of polycrystalline silicon on a predetermined substrate, and that the semiconductor layer contains hydrogen and fluorine near the grain boundaries of the polycrystalline silicon. The gist of the semiconductor device is that the concentration of either the hydrogen or the fluorine is distributed in the thickness direction of the semiconductor layer.

[Function] Normally, there are many dangling bonds at the grain boundaries of polycrystalline silicon, which have a great effect on carrier transport, but when hydrogen or fluorine is bonded, their function as defects is lost, and electrical properties have been significantly improved (US, P, 42
17374) However, the presence of excessive hydrogen or fluorine increases the internal stress of the film and reduces the heat resistance. Particularly, when hydrogen and fluorine are contained in the film forming process, the presence of excessive hydrogen and fluorine causes an increase in internal stress and adverse effects such as peeling of the film and inhibition of crystal growth. In addition, the hydrogen and fluorine contents must be carefully controlled in the film thickness direction, taking into account that the crystallinity differs between the early and late stages of the film formation process, and the concentration of grain boundaries and defects present in grain boundaries also differ. .

On the other hand, the bonding energy between silicon and fluorine is larger than that between silicon and hydrogen, so the effect of containing fluorine on electrical properties is smaller than that of hydrogen, and it also has superior heat resistance. .

However, a fluorine atom has a larger atomic radius than a hydrogen atom, and if a large amount is contained, the internal stress of the film will increase and the crystallinity will be impaired.

In the present invention, by simultaneously containing hydrogen and fluorine in a semiconductor and distributing the hydrogen concentration in the layer thickness direction, defects existing near grain boundaries are reduced throughout the semiconductor layer, and at the same time, adhesion to the substrate is increased. This makes it possible to do this without damaging the surface properties or crystal growth of the polycrystalline silicon film.

That is, as mentioned above, the CVD method (Chemical
Vapor Deposition), L P
CV D method (Low Pressure Chemical
l Vapor Deposition) or PCVD method (Plasma Chemical Vapor Deposition) or PCVD method (Plasma Chemical Vapor Deposition)
When a polycrystalline silicon thin film is formed using a method such as PourDeposition, the crystallinity differs between the initial stage and the latter stage of film formation, and there are generally many grain boundaries in the early stage of film formation. Therefore, in the early stage of film formation, the defect density is large, and in the later stage of film formation, the defect density decreases as the number of grain boundaries decreases. It is necessary to contain hydrogen or fluorine.

As a result of various experiments, the present inventor has found that the content of hydrogen or fluorine, or both, can be increased on the substrate side and decreased in the layer thickness direction, thereby dramatically reducing the defect density. I found it. Moreover, by reducing the content of hydrogen or fluorine, or both, on the opposite side of the film from the substrate side, the crystallinity is not impaired, and the electrical characteristics are not deteriorated.

The content of hydrogen and fluorine in a polycrystalline silicon film varies depending on the ratio of grain boundaries to the total film deposition.
In the present invention, IIJal is applied so as not to affect the electrical properties, crystallinity, and surface properties of the polycrystalline silicon film. The concentration of hydrogen is determined by the proportion of the entire polycrystalline silicon film, that is, [H] / ([s il +
[H+[F]), preferably lXl0-
The lower limit is preferably 5X10-' or more, most preferably 5X10-' or more. The concentration of fluorine is expressed as [F]/([si] + [H] + [F]), and the upper limit is preferably below 5X10-2 atomic ratio, optimally below 1X10-2 atomic ratio. It is desirable to
The lower limit is preferably greater than or equal to txto-' atomic ratio, and optimally l
Xl0-' atomic ratio or more is desirable.

This is because at the above concentration, hydrogen and fluorine segregate at grain boundaries and sufficiently compensate for defect levels.

In addition, in order to further improve the electrical properties, it is necessary to
It is desirable to have fewer S 1-H2 bonds than i-H bonds. This is because by increasing the amount of 51-M bonds compared to the amount of 5L-H2 bonds, crystallinity can be improved and carrier mobility can be increased.

The specific conditions for achieving this are as follows: 2,000
2 reflecting the peak at cm”” and the 5L-Hz coupling
Ratio to the peak at 100cm''(2000cm-'
It is preferable that the value (peak value at 2100 Cm-') be 1 or less.

As a method for containing hydrogen and fluorine near the grain boundaries of a polycrystalline silicon thin film, there is a method of forming a polycrystalline silicon thin film and then performing heat treatment in a plasma atmosphere of a gas mainly containing hydrogen or fluorine. That is, the substrate temperature is 100 to 500
Gas pressure 1O-5Tor r~l OTor at °C
r, high frequency power 10-3~102W/rr? , plasma is generated under a high frequency frequency of 5 to 50 GH2. At this time, hydrogen (H2) and fluorine (F2) are mainly used as gases, but an inert gas such as Ar % He % Ne may also be added.

For example, after forming polycrystalline silicon on a substrate, processing is performed in fluorine plasma. Thereafter, further treatment is performed in hydrogen plasma to incorporate fluorine and hydrogen into the thin film. Next, the opposite side of the substrate is annealed to a depth of approximately 100 to 1000 nm using a ruby laser, an excimer laser, or the like. At this time, the laser irradiated area may or may not be melted, but the crystal grain size will be expanded if it is melted. However, although hydrogen and fluorine in the laser irradiated area are released from the thin film by laser irradiation, when the thin film is melted by laser irradiation, the hydrogen and fluorine contents are extremely reduced. Therefore, after laser annealing, fluorine plasma treatment, hydrogen plasma treatment, or plasma treatment using both hydrogen and fluorine is performed again. The conditions for the fluorine or hydrogen or both plasma treatment at this time may be the same as the conditions for the fluorine plasma treatment performed before laser annealing, but preferably the substrate and plate temperatures are 100 to 300'C and the gas pressure is 10 -5~
10-'To r r, high frequency power is 10-3~IW/
rn'. The method described above yields a polycrystalline silicon thin film with relatively few grain boundaries, therefore low defect density, and low fluorine content near the surface.

Further, when forming a polycrystalline silicon thin film, the same effect can be obtained when hydrogen and fluorine are contained.

Plasma CVD is a method for forming polycrystalline silicon thin films.
method, sputtering method, ion blating method, etc., but here we will explain a method of forming a film on a substrate kept at a relatively low temperature by associating and reacting different radicals in a gas phase.

That is, active species (A) generated by decomposing a compound containing silicon and halogen are present in a film forming space for forming a deposited film on a substrate, and chemical interactions with the active species (A) occur. In forming a deposited film on the substrate by separately introducing active species (B) generated from a chemical substance for film formation and causing a mutual chemical reaction, the deposited film is supplying a gas having the effect of containing hydrogen or a decomposition product thereof, and irradiating the gas having the effect of containing hydrogen or the decomposition product thereof with light energy to increase the efficiency with which hydrogen is contained in the deposited film. increase.

Furthermore, it is possible to control the amount of hydrogen contained in the deposited film by changing the flow rate of the gas having the effect of containing hydrogen or its decomposition product, or the amount of the light energy.

In the present invention, as the compound containing silicon and halogen to be introduced into the activation space (A), for example, a compound in which part or all of the hydrogen atoms of a silane compound or a cyclic silane compound is replaced with a halogen atom is used. For example, S
1 u Y 2u+2 (u is an integer greater than or equal to 1, Y is F
, CIL, Br, and (1) is a dehydrated silicon halide, S i
Cyclic silicon halide represented by v Y2V (v is an integer of 3 or more, Y is the same as above), S 1 u HX Y
y (u and y are the same as above. x+y=2u or 2u
Examples include styrene or cyclic compounds represented by +2).

Specifically, for example, SiF4. (SiF2)s.

(SiF2)a, (SiF2)4,5i2Fe.

513Fa, SiHF3. SiH2F2+5iCJlt
4. (SiCA2)5. SiBr4゜(SiBr2)5
, 5i2Cf16, 5t2Bra.

5iHCn3, SiH3CA, 5fH2C112°5
Examples include those in a gaseous state or those that can be easily gasified, such as iHBr3, 5iHI3.5i2Cf13 F3.

In order to generate the active species (A), in addition to the above-mentioned compound containing silicon and halogen, other silicon compounds such as simple silicon, hydrogen, and halogen compounds (for example, F2
gas, Cλ2 gas, gasified Br2, ■2, etc.) can be used in combination.

Activated species (A) are generated by adding excitation energy such as heat, light, electricity, etc. to the above-mentioned species in the activation space (A).

In the present invention, the energy for generating the active species (A) in the activation space (A) may be electrical energy such as microwave, RF, low frequency, DC, etc., heater heating, Activation energy such as thermal energy such as infrared heating or light energy is used.

Activated species (A) are generated by adding excitation energy such as heat, light, electricity, etc. to the above-mentioned species in the activation space (A).

In the activation space (B) used in the method of the present invention,
Hydrogen gas and/or halogen compounds (for example, F2 gas, C, Q2 gas, gasified Br2.I2, etc.) are advantageously used as the chemical substance for film formation that generates the active species (B). Furthermore, in addition to these chemical substances for film formation, inert gases such as He, Ar, and Ne can also be used. When using multiple of these chemical substances for film formation, they may be mixed in advance and introduced into the activation space (B) in a gaseous state, or each may be individually supplied from independent sources. They may be introduced into the activation space (B) in a gaseous state, or may be introduced into independent activation spaces and activated individually.

In the present invention, the active species (A
) and the active fffi (B) can be appropriately determined according to the film forming conditions, the type of active species, etc., but is preferably 10:1 to 1:10 (introduction flow rate ratio), and more The ratio is preferably 8:2 to 4:6.

The compound containing halogen as a component may be introduced directly into the film forming space in a gaseous state, or may be introduced in advance into the activation space (A) or (B) or the third activation space ( It is also possible to activate it in step C) and then introduce it into the film forming space.

Further, as the gas or active species having the effect of containing hydrogen, hydrogen gas (F2) and hydrogen radicals (H) are advantageously used, but in addition to F2 and H, He, Ar, etc.
, Ne, and other inert gases may also be used.

Further, examples of the gas or active species having the effect of containing fluorine include fluorine gas (F2), CHF3. CF4.
C2F6. CBrF3゜C (1:J2□F2, CCf
13F, CCJ2F3.

C2 (1!2 SF6.NF, including fluorocarbons such as F4, boron fluorides such as BF3.

Fluorides such as PF, and ions such as fluorine radicals (F'') and CF'' generated by these gases are used.

Further, the deposited film formed by the above method can be doped with an impurity element during or after film formation. As the impurity element to be used, examples of the p-type impurity include B, AI! ,.

Suitable examples include elements of Group 3 B of the periodic table such as Ga, In, and TJ2, and examples of n-type impurities include, for example, P.
, As, Sb, Bi, and other elements in Group 5 B of the periodic table are preferred, but among these, B, G, etc.
a, P, Sb, etc. are optimal. The amount of impurities to be doped is appropriately determined depending on desired electrical and optical characteristics.

The substance containing such an impurity element as a component (substance for introducing impurities) is a compound that is in a gaseous state at room temperature and normal pressure, or at least in a gaseous state under activation conditions, and that can be easily vaporized with an appropriate vaporization device. The one you choose is preferred. Such compounds include PH3, F2 H4, PF
3, PFa.

PCIL3, ASH3, ASF3, AsF5.

ASCJZ3.5bHs, 5bFs, 5iHz.

BF3, BCJ23, BBr3, B2 H6.

B4 Hlo, B5 He・BsH++・BaH+
o.B, H,2, AuCJZ3, etc. can be mentioned.

The compounds containing impurity elements may be used alone or in combination of two or more.

FIG. 1 is a schematic diagram for explaining the semiconductor device of the present invention. The substrate 101 shown in FIG. 1 may be electrically conductive or electrically insulating. As the conductive support, for example, NiCr
, stainless steel, Au2゜Cr, Mo, Au, Ir, N
b, Ta, Ti.

Examples include metals such as V, Ti, Pt, and Pd, and alloys thereof.

As the electrically insulating support, films or sheets of synthetic resins such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, glass, ceramic, paper, etc. are usually used. .

FIG. 2 is a partial sectional view showing a schematic configuration of an example of a deposited film forming apparatus.

In FIG. 2, 201 is a deposition chamber in which a polycrystalline silicon film is deposited, and the inside of the deposition chamber 201 is connected to an exhaust system (not shown) through an exhaust pipe 221. can be maintained at a desired pressure. The pressure in the deposition chamber 201 is usually 10-5~
! , 0 Torr, preferably 10-' to 0. I To
r Adjusted to r. The deposition chamber 201 has a substrate support 2.
A desired substrate 203 is placed on 02.

Reference numeral 204 denotes a heater for heating the substrate, which is supplied with power through a conductive wire 205 and generates heat.The substrate temperature is not particularly limited, but is preferably 100 to 500°C, more preferably 150°C.
~400°C.

206 to 211 are gas supply sources, silicon compounds,
and, depending on the number of compounds containing hydrogen, a halogen compound, an inert gas, and an impurity element, which are used as necessary. When using liquid raw material compounds, a vaporizer is provided as appropriate. Gas supply source 206 in the figure
Those with a suffix a to 211 are branch pipes, those with b are flow meters, those with C are pressure gauges that measure the pressure on the high pressure side of each flow needle, and those with d or e. are valves for adjusting the flow rate of each gas.

212, 225, 226 are gas introduction pipes into the film forming space.

217 is a light energy generating device, such as a mercury lamp, a xenon lamp, a carbon dioxide laser, an argon ion laser, an excimer laser, or the like.

Light 218 is directed from the optical energy generating device e217 onto the entire substrate or a desired portion of the substrate using a suitable optical system.
is irradiated onto the raw material gas introduced in the direction of arrow 219 to excite the film forming raw material gas and cause it to react. The excited gas, etc. flows in the direction of the arrow 219 and reaches the substrate 20.
A deposited film of polycrystalline silicon is formed on the entire surface 3 or on a desired portion.

In addition, 214 and 223 are activation spaces that generate active species (A) and active species (B), and 213 and 222 are microwave plasma generators that generate active species.

This is a valve for adjusting the flow rate of hydrogen, fluorine, or each gas in the semiconductor layer of the present invention.

212, 225, 226 are gas introduction pipes into the film forming space.

217 is a light energy generating device, such as a mercury lamp, a xenon lamp, a carbon dioxide laser, an argon ion laser, an excimer laser, or the like.

Light 218 is directed from a light energy generating device 217 onto the entire substrate or a desired portion of the substrate using a suitable optical system.
is irradiated onto the raw material gas introduced in the direction of arrow 219 to excite the film forming raw material gas and cause it to react. The excited gas, etc. flows in the direction of the arrow 219 and reaches the substrate 20.
A deposited film of polycrystalline silicon is formed on the entire surface 3 or on a desired portion.

In addition, 214 and 223 are activation spaces that generate active species (A) and active species (B), and 213 and 222 are microwave plasma generators that generate active species.

The results of intensive study on the relationship between the content of hydrogen or fluorine, or both hydrogen and fluorine, and the layer pressure distribution in the semiconductor layer of the present invention are shown below.

After depositing a film using the apparatus shown in FIG. 2, a thin film transistor, which is a semiconductor device of the present invention, was fabricated and examined.

First, clean glass (Corntng $7059)
) was placed on the support stand 202.

Next, the inside of the deposition chamber 201 was evacuated using an exhaust device (not shown), and the pressure was reduced to about 10'' Torr. 50 sec of H2 gas was introduced from a gas supply cylinder into the activation chamber (B) 223 via the gas introduction pipe 225. Activation room (B) 22
The H2 gas and the like introduced into the film forming chamber 3 were activated by the microwave plasma generator 222 to become active hydrogen and the like, and introduced into the film forming chamber 201 through the introduction pipe 224.

On the other hand, 20scc of SiF4 gas is placed in the activation chamber (A) 214.
m was introduced through the gas introduction pipe 212. Activation chamber (A
) 214 was activated by the microwave plasma generator 213 and introduced into the film forming chamber 201 through the introduction pipe 212.

Further, F2 gas 10105e was introduced into the film forming chamber 201 through the gas introduction pipe 226.

While maintaining the pressure in the film forming chamber 201 at 0.02 Torr, 1 kW light from a Xe lamp is applied to the heater 204 in advance.
A polycrystalline silicon film was deposited by vertically irradiating the substrate 203 heated to 350° C. to cause the active species to chemically react with each other. At this time, F2 gas was simultaneously activated by the light irradiation and contained in the film. after that,
The flow rate of F2 gas was decreased over time as shown in FIG.

When the crystallinity of the deposited film of the polycrystalline silicon thin film sample obtained on the substrate 203 was evaluated by X-ray diffraction and electron beam diffraction, it was confirmed that it was a polycrystalline silicon film. Furthermore, when observed using a transmission electron microscope, the grain size of the polycrystalline silicon was approximately 5±0.2 μm. There was almost no variation in crystal grain size over the entire surface of the substrate. Further, when the surface condition of the sample was observed using a scanning electron microscope, it was found that the smoothness was good, there was no wave pattern, etc., and the film thickness unevenness was ±4% or less.

Next, the obtained non-doped polycrystalline silicon film sample was placed in a vapor deposition tank, and a comb-shaped AJ was placed at a vacuum degree of 1O-5 Torr.
: After forming an L gap electrode (length 250 μm, 5 mm), dark current was measured with an applied voltage of 10 V, dark current σd was determined, and the polycrystalline silicon film was evaluated. Furthermore, SIM
A profile of hydrogen content in the depth direction was obtained by S (secondary ion mass spectrometry).

In addition, the localized level density in the film was measured by the field effect method and the ESR method.

The above film formation conditions and evaluation results of the deposited film are shown in Table 1 and
It is shown in Table 2, FIG. 9, and FIG. 16.

As shown in FIG. 9, the hydrogen content in the film decreases in the film thickness direction, with more on the substrate side and less on the side opposite to the substrate. Along with this, the localized level density in the film decreases, and 1017
The value is extremely smaller than that of cm-3e V, and it is large on the substrate side and small on the side opposite to the substrate (2 to 8 x 10 I6c m-3e V-'
). Regarding hydrogen bonds, in the IR infrared absorption spectrum, there is a peak at 2000 cm-' and a peak at 210 cm-'.
The peak ratio at 0 cm-' is 0.7, which is 1 or less. The F content and the localized level density in the film shown in Table 2 are the values at a depth of about 0.5 μm in film thickness.

As described above, it was found that a good semiconductor film was obtained.

The experiment was carried out in exactly the same manner as in the above experimental example except that fluorine gas was introduced into the film forming chamber 210 through the 10105e gas introduction pipe 226.

While maintaining the pressure in the film forming chamber 201 at 0.02 Torr, 1 kW light from a Xe lamp is applied to the heater 20 in advance.
A polycrystalline silicon film was deposited by vertically irradiating the substrate 203 heated to 350° C. by irradiating active species to chemically react with each other. At this time, F2 gas was simultaneously activated by the light irradiation and contained in the film. Thereafter, the flow rate of F2 gas was measured over time by the decreasing ESR method as shown in FIG.

The above film forming conditions and the evaluation results of the deposited film are shown in Table 3 and
It is shown in Table 4, FIG. 9, and FIG. 16.

As shown in FIG. 9, the fluorine content in the film decreases in the film thickness direction, being higher on the substrate side and lower on the side opposite to the substrate.

Along with this, the localized level density in the film decreases, and 10
"c m-3e V-'J: r) The value is extremely small, and it is large on the board side and small on the opposite side (2 to 8 x 1018 cm m-
3e V-'), the H content and the local level density in the film shown in Table 4 are the values at a depth of about 0.5 μm in film thickness. As described above, it was found that a good semiconductor film was obtained.

Next, we investigated the case where hydrogen and fluorine were introduced simultaneously. In this case, as in the case where hydrogen or fluorine is introduced alone, by reducing the inflow of hydrogen and fluorine, the content of hydrogen and fluorine in the film decreases in the film thickness direction, and on the substrate side, the content of hydrogen and fluorine decreases in the film thickness direction. It has been found that the distribution can be made to be more concentrated and less distributed on the side opposite to the substrate. Under the film forming conditions shown in Table 1, when hydrogen and fluorine are simultaneously introduced at the hydrogen and fluorine gas flow rates shown in Figure 3, the distribution of hydrogen and fluorine in the film thickness direction as shown in Figure 18 is obtained. It was also determined that the film had a localized level density distribution as shown in FIG. 20, indicating that a good film was obtained.

Next, a thin film transistor (hereinafter abbreviated as TPT) made of polycrystalline silicon, which is a semiconductor device of the semiconductor invention, will be described. FIG. 15 is a schematic partial perspective view showing the structure of the TPT of the present invention.

As shown in Figure 15, polycrystalline silicon TPT1500
is on a substrate 1506 made of glass, ceramic, etc.
A gate electrode 1501, an electrically insulating layer 1504 covering the gate electrode 1501, and a semiconductor layer 1505 made of polycrystalline silicon are sequentially laminated to form the semiconductor layer 1.
A first 12 layer 1507 and a second n+ layer 1508 are provided on the surface 1509 of the 505 and spaced apart in a juxtaposed relationship, and further on the first 01 layer 1507 a source TL pole 1502 and a The drain electrode 1 is on the n+ layer 1508 of 2.
503 are respectively provided.

Surface (green surface) on semiconductor 51505 15
The first n1 layer 1507 and the second n0 layer 1508 provided in contact with the semiconductor layer 1505 are formed without exposing the layer surface 1509 to the atmosphere or oxygen after the semiconductor layer 1505 is formed. Note that the distance 1IiltL between the source electrode 1502 and the drain electrode 1503 is 50 μm,
The length Z of the source electrode 1502 and the drain electrode 8i 1503 is 10 mm.

[Example] The present invention will be specifically explained using Examples below.

(Example 1) Using the apparatus shown in FIG. 2 described in the operation section, a film was deposited under the conditions shown in FIG. 4 and evaluated. The results are shown in FIGS. 10 and 17. As can be seen from FIG. 10, the hydrogen content in the film decreased in the film thickness direction according to the amount of hydrogen introduced, and the film was formed with more hydrogen on the substrate side and less on the side opposite to the substrate. The IR spectral ratio (value of peak at 2000 cm-'/value of peak at 2100 cm-') was 0.8. The local level density in the film is also 10-” cm-3e V
−' or less, indicating that it decreases in the film thickness direction. Further, it was found that σd had a value of 7×10-'(Ω·cm)-', and the crystal grain size was 4.3 μm, indicating that a good quality film was obtained.

(Example 2) Under the same conditions as Example 1, only the hydrogen gas introduction conditions were changed to 5th.
It was produced by making changes from Fig. 8 to Fig. 8.

Table 5 shows the evaluation results for the obtained samples No. 2-1 to No. 2-4. The F content and the local level density in the film are values at a depth of approximately 0.1 μm. Example 1
Similarly, there is a tendency for the hydrogen content to decrease in the film thickness direction,
The film quality was also found to be good.

(Example 3) The thin film transistor shown in FIG. 15 was manufactured using the manufacturing process described in the operation section. Semiconductor 1505 in this example
As for the film deposition conditions for sample No. 3-1, the hydrogen introduction conditions were the same as in Example 1, as shown in FIG. 4, and for sample No. 3-2, the hydrogen introduction conditions were the same as for sample N of Example 2.
The same conditions shown in Figure 8 as in 2-4 were used. The drain electrode of the fabricated thin film transistor was grounded, and the characteristics were measured when a medium voltage was applied to the source electrode and gate electrode while changing.

A good saturation characteristic is obtained in the drain electrode io-drain voltage vo characteristic, and a high current of 5×10-”A is obtained with a gate voltage of 1°V and a drain voltage of 10V.By changing the gate voltage VG, Table 3 shows the TPT characteristics obtained from the results of measuring the drain current ID.

It has been found that the TPT using the polycrystalline silicon film obtained above exhibits good characteristics.

(Example 4) Using the apparatus shown in FIG. 2, a film was deposited on a glass substrate using the film formation method described above under the conditions shown in Table 7,
Table 8 shows the properties of the obtained film, and Table 9 shows the properties of the sample made using the thin film transistor manufacturing method described in the operation section. Among the conditions in Table 7, SiF4. The H2 flow rate, discharge power, and substrate temperature were varied.

In all cases, films of good quality were deposited, and the TPT characteristics were also very good.

(Example 5) Using the apparatus shown in Figure 2, hydrogen gas was reduced under the conditions shown in Figure 4, and film samples were deposited under the same conditions as in Table 3 for other processes, and evaluation was performed. Ta. The results are shown in FIGS. 10 and 17. As can be seen from FIG. 10, the fluorine content in the film decreased in the film thickness direction according to the amount of fluorine introduced, and the film was fabricated with more fluorine on the substrate side and less on the side opposite to the substrate. The IR spectral ratio (value of peak at 2000 cm-'/value of peak at 2100 cm-') was 0.8. The localized level density in the film also decreased to below 1017 cm-3 eV-', indicating that it decreases in the film thickness direction.

Further, σd also showed a value of 8×10−′ (Ω·cm)”, and the crystal grain size was 5 μm, indicating that a good quality film was obtained.

(Example 6) Same conditions as Example 5, only F2 gas introduction condition was changed to 5th.
As a result of fabrication with the changes shown in FIGS. 8 to 8, it was found that the hydrogen content tended to decrease in the film thickness direction, similar to Example 1, and the film quality was also good. The results are shown in Table 10. The H content and the local level density in the film have values at a depth of approximately 0.1 μm.

(Example 7) The thin film transistor shown in FIG. 15 was manufactured using the manufacturing process described in the operation section. Semiconductor 1505 in this example
As for the film deposition conditions for sample No. 7-1, the fluorine introduction conditions were the same as those in Example 5, as shown in FIG. 4, and for sample No. 7-2, the fluorine introduction conditions were the same as for sample No. .

The same conditions shown in Figure 8 as in 6-4 were adopted. The drain electrode of the fabricated thin film transistor was installed, and the characteristics were measured when varying ten voltages were applied to the source electrode and gate electrode.

Drain electrode ID-drain voltage V. Good saturation characteristics were obtained, and a high current of 5×10 arc A was obtained with a gate voltage of 10 V and a drain voltage of 10 V. Gate voltage V. Table 3 shows the TPT characteristics obtained from the results of measuring the drain current 10 while varying the .

It has been found that the TPT using the polycrystalline silicon film obtained above exhibits good characteristics.

(Example 8) Using the apparatus shown in FIG. 2, a film was deposited on a glass substrate under the conditions shown in Table 12 using the film formation method described in the section, and the characteristics of the obtained film were Table 13 shows the characteristics of the sample made using the thin film transistor manufacturing method described in the operation section, followed by Table 14. In Table 12, among the conditions in Table 3, the flow rates of SiF4 and H2, discharge power, and substrate temperature were changed.

In all cases, good films were deposited, and the TPT properties were also very good.

(Example 9) Next, a TPT was manufactured using a film obtained by introducing hydrogen and simultaneously introducing fluorine under the film forming conditions used in Example 5.

The distribution of hydrogen and fluorine in the film and the distribution of local level density when hydrogen and fluorine are introduced at the flow rates of the profiles shown in Figs. 3 and 4 are shown in Figs. 18 and 19, respectively. This is shown in FIGS. 20 and 21.

In each case, it was shown that as the hydrogen content in the film decreased, the local level density decreased significantly and became 1017 or less. Further, the thin film transistor using this film showed good characteristics as shown in Table 15.

[Effects of the Invention] As described above, the semiconductor device of the present invention has a semiconductor layer made of polycrystalline silicon with very low defect density and high adhesion to the substrate. It can be used to drive displays and sensors with great effects.

[Brief explanation of drawings]

FIG. 1 is a plan view of a semiconductor device of the present invention, FIG. 2 is a cross-sectional view of a manufacturing apparatus for a semiconductor device of the present invention, and FIGS. 3 to 8 are flow rate change curves of hydrogen gas or fluorine gas during film formation. The graphs, Figures 9 to 14 and Figures 18 to 19, show the content distribution of hydrogen or fluorine in the depth direction in the deposited film using SIM.
A graph of the results analyzed by S, FIG. 15 is a perspective partial view of a thin film transistor formed by the method of the present invention,
FIGS. 16 to 17 and 20 to 21 are graphs showing the distribution of localized level density in the film thickness direction. 101...Substrate, 102...Deposited film, 201...
Deposition chamber, 202... Substrate, 203... Deposited film, 20
4... Heater for heating the substrate, 206-211... Gas supply source, 214... Activation chamber (A), 223...
Activation chamber (B), 217... light energy generator,
1500... Thin film transistor, 1501... Gate electrode, 1502... Source electrode, 1503... Drain electrode, 1504... Insulating layer, 1505... Semiconductor layer, 1506... Substrate, 1507-1 ... n middle layer, 1507-2=・n4- layer, 1508 ... surface layer. FIG. 3 FIG. 4 Flow rate of H2 gas or F2 gas (SCCm) (
SCCm3 (atomic ratio)
(atomic ratio) (atomic ratio)
(atomic ratio) (atomic ratio)
(Atomic ratio) Film thickness (μm) (cm'ev'・) (Atomic ratio) Ccm-3ev-1) (Atomic ratio)

Claims (6)

[Claims] (1) A semiconductor device, which has a semiconductor layer made of polycrystalline silicon on a predetermined substrate, the semiconductor layer containing hydrogen and fluorine near the grain boundaries of the polycrystalline silicon, and the concentration of the hydrogen and the fluorine. A semiconductor device characterized in that either one of these is distributed in the thickness direction of the semiconductor layer. (2) The semiconductor device according to claim 1, wherein the maximum concentration of hydrogen in the semiconductor layer is 10 atomic ratio or less. (3) The semiconductor device according to claim 1 or 2, wherein the concentration of hydrogen in the semiconductor layer is 5 atomic ratio or less. (4) The semiconductor device according to any one of claims 1 to 3, wherein the hydrogen concentration or fluorine concentration in the semiconductor layer is high on the substrate side and low on the side opposite to the substrate. (5) In the infrared absorption spectrum in the semiconductor layer, 20
Peak at 00cm^-^1 and 2100cm^-^
5. The semiconductor device according to claim 1, wherein the ratio to the peak at 1 is 1 or less. (6) Localized level density in the semiconductor layer is 10^1^7 cm^
6. The semiconductor device according to claim 1, wherein the voltage is -^3eV^-^1 or less.