JPS61159626A - Semiconductor device - Google Patents

Abstract

PURPOSE:To permit the flow of large current in a non-linear element consisting of a non-single crystalline semiconductor added with hydrogen or halogen element by selecting suitably the thickness and additive of the semiconductor. CONSTITUTION:The 1st electrode 22 consisting of chromium is formed on a glass substrate 20 and thereafter a composite diode 2 consisting of the non-single crystalline semiconductor which consists of an N-type semiconductor, I-type semiconductor 13 and N-type semiconductor 14 and is added with hydrogen or halogen element is formed thereon. The I-type semiconductor 13 has 0.1-0.5mu thickness and consists essentially of silicon added with carbon, oxygen or nitrogen. The 2nd electrode 21 consisting of chromium is further formed on the diode 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention relates to solid-state display devices, image sensors, etc., which solidify display parts of microcomputers, word processors, televisions, etc. by providing a display element, preferably a liquid crystal display panel. Alternatively, the present invention relates to a semiconductor device having nonlinear characteristics that is applied to a liquid crystal printer.

``Prior Art'' For solid-state display panels, a system in which each picture element is controlled independently is effective for large-area displays. A panel using such active elements uses a non-linear NIN junction structure (no boron is added as an impurity in the ■-type semiconductor), which uses amorphous silicon connected 1:1 to all pixels. element is known. This NIN or N
Regarding N-N junction characteristics, V, D, Mackenzi
e, etc. (Philosophical Magazine,
8.1982 46 Na4377-389) investigated the basic physical properties as a space charge control current. However, this paper not only does not mention the effectiveness of actively adding carbon, oxygen, or nitrogen to this single layer, but also adds boron to the single layer in layers (I
) layer (substantially one intrinsic layer) (no. In addition, the thickness of one layer is extremely thick at 0.65 μm or 0.7 to 2 μm, and it is not suitable for solid-state display devices, which is an application of the present invention. It is completely inadequate and has not been optimized in any way.

Even if this NIN junction is used, even if it has origin symmetry in voltage-current characteristics in DC (direct current) characteristics, the reality is that no consideration has been made in terms of frequency response characteristics.

"Problems to be Solved by the Invention" Therefore, if this nonlinear element is used in a liquid crystal display, the frequency characteristics will become a problem because the liquid crystal itself is driven by alternating current. When using a known NIN junction made only of amorphous silicon (the thickness of one layer is 0.6 to 2 μm), the frequency characteristics could not be followed even at 1 KHz.

This has been found to be a fatal fact when the active element of a display requires a frequency characteristic of at least 40 KHz.

"Means for Solving the Problem" In order to solve the problem, the present invention provides a nonlinear element made of a non-single crystal semiconductor doped with hydrogen or a halogen element, in which the thickness of the I-type semiconductor is reduced as much as possible. This is an attempt to reduce the series resistance in a comb-type semiconductor.

As a result, it was found that a large current could flow when a voltage of 5V was applied in the V-I characteristic in the range of 0.1 to 0.5μ. However, it is necessary to extend the frequency characteristics to 40 KH2 or more, to prevent deterioration of the NI junction interface due to repeated applied voltages, and to further improve the current (
In order to further lower the off-state current, a ■-type semiconductor (silicon hydride only, with no active addition of carbon, nitrogen or oxygen) is completely insufficient, and carbon, oxygen or 5i(N)-9ix with added nitrogen
C1-x (0<X<1) (10,1~0.5/
J) It has been experimentally found that it is effective to have a NIN junction with a -5t(N) structure. The present invention is based on this fact.

In addition, by creating a cos+pensated I type (I) type in which boron is added to an extent that cancels out the N- conversion that would occur without addition of boron in one layer, the off-state current can be reduced to a so-called single layer without boron addition. The size is 1/1000 or less compared to the original size. And 5i(N) −5ixC+−x(0<X<1)((1
)0.1~0.5μ))-5i(N) structure N(I)N
The main purpose is to have a bond.

"Function" With such a structure, it is possible to minimize the off-state current at Ov, to have a shape symmetrical to the origin in the V-1 characteristic, and to be able to respond even when the frequency characteristic is 40KH2 or more, and for AC drive elements such as It has been found that it is extremely effective as an element for liquid crystal devices. of course,
When forming one layer, if a so-called multi-chamber method is used in which the first N-type semiconductor, the second ■-type semiconductor, and the third N-type semiconductor are reacted in different connected reaction furnaces, this one layer The amount of phosphorus mixed into the N-type semiconductor layer is relatively reduced. Therefore, when forming one layer,
The amount of boron added for offset is further increased by 175 to 1/3.
It is possible to reduce the bonding characteristic to 0, and it is also possible to make the bonding characteristics at the Nl interface steeper.

Furthermore, in the known MIN (metal-insulating film-metal structure), the metal-insulator interface, which is important for determining its characteristics, tends to vary slightly depending on the process.
The NIN or N(1)N structure of the present invention does not use such a delicate interface between different materials, but uses a semiconductor-semiconductor junction method, so the parasitic capacitance at the interface is small and the frequency characteristics can be extended to higher frequencies. I can do it.

The present invention will be explained below according to examples.

"Example 1" This FIG. 1 will be abbreviated below.

FIG. 1(A) shows a longitudinal cross-sectional view of an actual device structure.

In FIG. 1(A), Corning 7059 glass (20) was used as the light-transmitting insulating substrate. A conductive film of 100% chromium or molybdenum for leads, electrodes and light shielding is applied to this upper surface by sputtering or electron beam evaporation.
Lamination was similarly performed to a thickness of 0 to 4,500 people.

After this, NI is applied to the entire surface by plasma vapor phase reaction method.
A composite diode made of a non-single crystal semiconductor doped with hydrogen or a halogen element having an N or N(1)N structure was formed. That is, N-type semiconductor (12) and silane (13)
．． By performing high frequency glow discharge of 56MHz, 2
A non-single-crystal semiconductor is produced by adding hydrogen or a halogen element onto a surface on which a substrate is formed and which is maintained at a temperature of 00 to 250°C. Its electrical conductivity is 10-' to 10'' (Qci+)-
', and the thickness was 300 to 3,000 people, for example, 1,500 people, and the vacuum was sufficiently evacuated to 10-' to 10-' torr. Furthermore, silane (SillHz*
-x (for example, SiH* with m=1) was introduced to form a ■-type semiconductor. At this time, carbon is simultaneously converted into CzHi, Czh, C
Ft.

HgCzh or methylsilane (SiHn(CH3)4
-i n -1 to 3) were mixed. Here, for example, n
= 2 MS (HzSi (CHs) z) was used as the carbon additive. That is HzSi (CH3) z/5
iHa = 1/10 to 1/200, for example 1/80 (flow rate ratio). This mixed reactive gas is introduced into a plasma reactor to cause a plasma reaction, and a non-single crystal semiconductor (13) having an intrinsic conductivity type to which hydrogen or a halogen element is added is formed by 0.1-0. 5μ thickness e.g. 0.3μ
It was formed by laminating it on the N-type semiconductor (12) to a thickness of . Furthermore, the vacuum was sufficiently evacuated to 10-'''10-' torr. Again, the same N-type semiconductor (14) was
Laminated to a thickness of 00 to 1500 people, for example 500 people
It was made into an N-junction.

Thereafter, chromium was formed on the upper surface to a thickness of 0.1 μm for light shielding. Further, this chromium was etched using a first photomask (1), and using this chromium as a mask, the underlying semiconductor, first electrode, and lead (22) were etched to form a laminate. This side was made as vertical as possible. These were entirely coated with a light-transmitting organic resin that was sensitive to ultraviolet light using a coater. In addition, ultraviolet light was irradiated from the lower side (back side) of the substrate to expose areas other than the organic resin above the laminate. Then, the organic resin on this laminate was eluted without using a mask, and then aired to make the upper surface of this organic resin (17) substantially the same as the upper surface of the laminate.

Furthermore, on top of this, SnO□ or I as a CTF is applied to the entire surface.
TO was laminated to a thickness of 500 to 3,500 layers by electron beam evaporation or sputtering. Next, except for the area where this CTP is provided as an electrode of a liquid crystal display or a lead for measurement here, the other part is covered with a second photomask.
A second electrode was formed by removing the second electrode by photoetching.

Thus, the structure of FIG. 1(A), that is, the glass substrate (20
), the first electrode (22) consisting of a chromium electrode on N(
12) An NIN junction type composite diode (2) made of an I (13) N (14) semiconductor stack and a second electrode (21) made of chromium were successfully obtained. This NIN
'& The symbol for the composite diode is shown in FIG. 1(B).

Figure 2 shows the voltage-current characteristics (V-1
characteristics).

The diagram in which the horizontal axis shows voltage and the vertical axis shows current on a log scale was obtained at 400°, p x 30 μ (ie, denoted as S).

The curve (15) in Figure 2 shows the conventionally known N, I, N structure (
These are the characteristics obtained with the semiconductor (2) having a semiconductor (intrinsic semiconductor made only of silicon to which hydrogen is added and no boron is added in one layer). In this case, all the semiconductors of NIN are non-single crystal semiconductors of silicon containing hydrogen. In this case, the thickness of one layer is 1μ (even if the off-state current is 7Xl0-?A
/SL could not be obtained.

For this reason, even if current is applied to this NIN through this element in a liquid crystal display, which is the main application of the present invention, it becomes a leakage current and discharges during the hold time, making it completely impractical. .

In the present invention, carbon was simultaneously added to one layer during film formation. That is, when forming one layer in Example 1, D/5iH4 was set to 1/80.

The V-I characteristic when this one layer is set to 5ixCt-x (0<X<1) is shown in curve (16) in Figure 2.Then, the off-state current is )(7)
Approximately 1/100 Nisurukoto is now possible.

FIG. 3 shows an investigation of the frequency characteristics of a composite diode having this NIN structure.

In the drawings, the impedance at the time of direct current is set as Z(0), and the frequency Z at the time of alternating current is standardized thereby.

This data is bias voltage -4V, AC voltage 0.01V
This is the frequency-impedance characteristic when

Conventionally known NI made only of silicon to which hydrogen is added
In the N structure, the decrease begins at IKHz as shown in curve (15'), and at 10KHz it has dropped to the initial value of 40χ.

On the other hand, when carbon is added to one layer as in the present invention, this graph is set to DMS/SiH*-1/100. curve(
16') was obtained. In other words, even at 100KHz, the initial value of 80χ
It can be seen that it is maintained. That is, it has been found that the requirements for an active element, such as a frequency response of 40 KHz or more and an on-current of >10-'A/S (voltage ±5 V), can be satisfied.

Example 2 This example is similar to Example 1, but B! This is a type (1) semiconductor doped with H, to the extent that it cancels it out. In this example, the conditions were BJh/5iHa = 7 PPM (flow rate ratio) and DMS/SiH*Harm 6. Thus, it has an N(I)N structure, and the special Ni(1) layer is 5ixC+-x
(0<X4), and an amount of boron was added to compensate for the contamination of naturally occurring hydrogen and phosphorus. Then,
In the V-■ characteristic, curve (17) in Figure 2 was obtained. In other words, it has become possible to reduce the on-current to 5 to 10XIO-'^/S (when 5V is applied) and the off-current to 7X10-"A/S. This 0MS/5iHn-175
If it is increased to 0, the off-state current can be lowered to 10-'A/S.However, if it is increased to 1/10 or more, the on-current will also be less than 10-'A/S, and the LCD It no longer has enough current to charge the battery.

In FIG. 3, such boron and carbon added N
(1) The frequency characteristics of the N-structure element are shown in curve (17').

Judging from this curve, the initial value of 97χ was maintained even at 100 KH2, and 85χ was maintained even at IMH2, indicating that extremely satisfactory characteristics had been achieved for the first time.

It was found that this N(I)N structure has an on-current of 10-' A/S and an off-current of less than 10-' A/S, satisfying the requirements for other active devices. .

In this N(1)N structure doped with boron and carbon, if the thickness of one layer is 0.5μ or more, the off-state current is 10
-'' A/S or less can be achieved, but the on-current decreases to less than 10-'A/S, and the thickness is 0.
If it is less than 1 μm, the variation in thickness over a large area becomes large, and the non-uniformity of characteristics in the matrix within a large area becomes noticeable. Therefore, when trying to drive this active element at θ~±5v, (1) the layer thickness is 0
．． It has been found that 1-0.5μ is preferred.

"Effects" As described above, the present invention has carbon in one layer in order to construct a composite diode that has V-I characteristics symmetrical with respect to the origin and guarantees response up to high frequencies of 40 KH2 or higher. It was added. At the same time, boron is added to offset naturally occurring N-type.

The structural characteristics of a composite diode are not an N(1)N junction.
, P(1)P junction properties may be used.

However, if we consider the Stebla-Lonski effect, N(1)
It is estimated that N-junction is more preferable. Furthermore, even if the semiconductor is not silicon to which hydrogen is added but silicon to which a halogen element such as fluorine is added, 5ixGet-x (0≦
It may be x<1).

Although the present invention has characteristics similar to those of the conventionally known old structure, since there is less capacitance component at the interface, it can be driven to a high frequency. For this reason, for a large display (400X 1920),
This is especially convenient. Since the characteristic obtained by the present invention has a minimum current value of Ov, it is effective for AC drive systems. Furthermore, since the threshold value can be controlled by the process conditions during stacking of semiconductor layers using a vapor phase reaction method, it has the characteristic that gradation can be easily controlled.

In the present invention, carbon was added within one layer. However, instead of carbon, NgO may be added instead of DNS to add oxygen, or NH3 may be added to add nitrogen. and 5i-3iOz-x (0<X<2) -st, st
-SiJ<-x (0<X<4) -3t structure and adding compensating boron to the active layer in parentheses (1)
Layering is effective.

However, since these oxygen and nitrogen easily become insulators, the amount of addition thereof must be controlled more delicately, and it is more difficult to manufacture them than carbon.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view (A) of the composite diode of the present invention. An equivalent circuit (B) is shown. Figures 2 and 3 show a conventionally known NIN junction using only amorphous silicon, an NIN junction in which carbon is added to the I-type semiconductor of the present invention, and a NIN junction in which carbon and compensation boron are added to the I-type semiconductor of the present invention. The voltage-current characteristics and impedance-frequency characteristics of the N(I)N junction are shown.

Claims (1)

[Claims] 1. A first non-single crystal semiconductor having one conductivity type, a second non-single crystal semiconductor that is intrinsic on the semiconductor or substantially intrinsic due to the addition of boron, and In the non-linear element having a semiconductor provided by stacking the first non-single crystal semiconductor and a third semiconductor having the same conductivity type, the second semiconductor has a thickness of 0.1 to 0.5 μ. Additionally, a semiconductor device characterized in that its main component is silicon to which carbon, oxygen, or nitrogen is added. 2. A semiconductor device according to claim 1, wherein the second semiconductor has an amorphous structure, and 1 to 20 ppm of boron is added to silicon.