JPS61159624A - Semiconductor device - Google Patents

Abstract

PURPOSE:To decrease the off current when an impressed voltage is made zero by using a non-linear element consisting of a non-single crystalline semiconductor added with hydrogen or halogen element. 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 added with the hydrogen or halogen element having an N (I) N structure is formed thereon by a plasma vapor reaction method. The diode 2 consists of the laminate of an N type semiconductor 12, an (I) type semiconductor 13 and an N type semiconductor 13. The 2nd electrode 21 consisting of chromium is 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 to all pixels in a l:1 ratio. element is known. This NIN further I
Regarding N-N junction characteristics, V, D, Mackenzi
e etc. (Philosophical Magazine
8. 1982 46 11, 4377-389), the basic physical properties as a space charge control current have only been studied. However, in this paper, the (1) layer (substantially one intrinsic layer) in which boron is added in a layered manner to this I layer.
There is no consideration at all. Even if this NIN junction is not used, the ■-type semiconductor is substantially N-type due to hydrogen, phosphorus, and other impurities added thereto.

For this reason, an NIN junction is provided and the applied voltage is sufficiently Ov.
It is not possible to reduce the current that flows when the current is brought close to . As a result, it is impossible to increase the 0N10FF ratio to three digits or more, so although it has the potential to be used as an active element, it has no practical use at all.

``Problem to be solved by the invention'' For this reason, the current so-called OFF current (OFF current) when the applied voltage is Ov is N
In the IN junction, 6 xlO-'A/S (1,2Xl0-'
cm, that is, an area of 30 μ×400 μ is hereinafter referred to as S), that is, a large value of 5.0×10 −′A/cm”.

It has been found that this is due to phosphorus being mixed into the I-type semiconductor layer of the NIN-type semiconductor element.

"Means for Solving the Problem" In order to solve the problem, the present invention uses a nonlinear element made of a non-single crystal semiconductor to which hydrogen or halogen elements are added, and the I-type semiconductor contains no additives. DoN
-compens with boron added to offset the
By making the I-type buried (1) type, the off-state current can be reduced to 3 Xl0-"^/S (2,5Xl0-'^/cm
The size has been reduced to 5/1000. In addition, carbon is added to this layer (1) to increase the off-current by 4 x
1O-''A/S and further reduced to 1/100.

And Si −5ix(, −x(0<X
<1) The main feature is that it has an N(1)N junction of a -Si structure.

The threshold voltage of such a composite diode is obtained by making diode characteristics opposite to each other, but its build-in (rise) voltage (threshold) depends on the thickness of the ■-type semiconductor, the resistivity, and the NI interface or its By controlling the junction characteristics in the vicinity, the off-state current of the device and the on-state current at a given voltage can be determined. In particular, if this element is to be used for controlling a display, a small value is required for the off-state current of this element. Further, the on-current needs to have a capacity to add the amount of charge necessary for a liquid crystal element to be charged at, for example, 5V in a predetermined time (for example, 10-s to 10'' A/S for a liquid crystal display element).

In order to further reduce this off-current, the present invention forms a cancellation type (1) layer by adding boron to an extent that cancels out the naturally occurring N- in the first layer.

"Function" Therefore, it is possible to minimize the off-state current at Ov and to have a shape symmetrical to the origin in the V-■ characteristic, which has been found to be extremely effective as an AC drive element, such as an element for liquid crystal elements. did.

Of course, when forming one layer, the first N-type semiconductor, the second
If a so-called multi-chamber method is used in which a third I-type semiconductor and a third N-type semiconductor are reacted and formed in different connected reactors, the incorporation of phosphorus from the N-type semiconductor layer into this one layer will be relatively small. becomes less. Therefore, when forming one layer, the amount of boron added for offset is 115~l.
It is possible to add as little as /30, and it is effective to add this amount to an extent that does not make one layer P-type.

Furthermore, in the known WIN (metal-insulator-metal structure), the important specific metal-insulator interface becomes extremely delicate, but in the N(1)N structure of the present invention, such a delicate interface made of different materials becomes extremely delicate. Since it uses a semiconductor-semiconductor junction method without using an interface, parasitic capacitance is small and frequency characteristics can be extended to high frequencies.

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. Chromium or molybdenum, which is a conductive film for leads, electrodes and light shielding, is deposited on the top surface using sputtering or electron beam evaporation.
Laminations were similarly formed to a thickness of ~4,500.

After that, N(
I) A composite diode made of a non-single-crystal semiconductor doped with hydrogen or a halogen element having an N structure was formed.

That is, the N-type semiconductor (12) is silane at 13.56MHz.
By performing high frequency glow discharge of 200 to 250
A non-single crystal semiconductor to which hydrogen or halogen elements are added is fabricated on a surface of a substrate maintained at a temperature of .degree. Its electrical conductivity was between 10-s and 10''t(Ωc+++)-', and the thickness was between 300 and 3000, for example 1500.

Furthermore, the vacuum was sufficiently drawn down to 10-6 to 10-' torr. Furthermore, BtH, is B2■h/Si
A (I) type semiconductor was formed by introducing silane (SimH, or 2, for example, SiHn with m=1) mixed with Ht=7 PPM. At the same time, methylsilane (SiHn(C)
Hz)4-n n =1 to 3) is effective. That is, for n-2, HzSi ((:H2)
z/5in4= 1/10~1/200 e.g. 1/80
(flow rate ratio), this mixed reactive gas is introduced into a plasma reactor to cause a plasma reaction, and the intrinsic value, that is, the substantial For example, a non-single crystal semiconductor (13) having an intrinsic conductivity type is deposited to a thickness of 0.1 to 0.5μ.
．． It was formed by laminating it on the N-type semiconductor (12) to a thickness of 3 μm. Furthermore, the chamber was sufficiently evacuated to 10-b to 10-' torr. Again, similar N-type semiconductor (14) is
00 to 1500 people, for example, 500 people thick.
It was an IN junction.

The impurity distribution in such a laminated structure is shown in FIG. 1(C).

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 (3), and using this chromium as a mask, the underlying semiconductor, first electrode, and lead (11) 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 dissolved away without using a mask and cured, so that the top surface of this organic resin (17) and the top surface of the laminate were approximately the same.

Furthermore, on top of this, 5nOz or I as a CTF is applied as a whole.
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 CTF 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 N(1)N junction type composite diode (2) made of (I) (13)N(14) semiconductor laminate (2) and a second electrode (21) made of chromium were successfully obtained. This N
(1) The symbol of the N structure is shown in FIG. 1(B).

FIG. 2 shows voltage-current characteristics (V-■ characteristics) of the conventional example and the present invention.

The horizontal axis shows voltage and the vertical axis shows current on a log scale. The drawing was taken at 400μ x 30μ (ie designated as S).

The curve (15) in FIG. 2 is the conventionally known N, 1. N structure (
Semiconductor (2 layers with no boron added)
). In this case, all of the N, I, and H semiconductors are silicon non-single crystal semiconductors containing hydrogen.

Off current is 7Xl0-? The A/S value was extremely large. 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. . It has been found that the reason for this is that part of the impurity phosphorus is mixed into the IN during film formation in the I-type semiconductor plasma reactor.

In FIG. 2, curve (16) shows the properties obtained with the structure of the invention. That is, the first semiconductor N(12), which is an N-type semiconductor made of non-single crystal silicon to which hydrogen is added, and the substantially intrinsic non-single crystal shown in (1) to which hydrogen is added and boron is added. A second semiconductor (I) made of a crystalline semiconductor (
13) A semiconductor (2) having a third semiconductor N (14) structure having the same characteristics as the first semiconductor. In particular, in the (I) type semiconductor, BtHi/5iH4 = 7PPM
is added. In this case, the voltage-current characteristic is the curve (
22) was obtained. That is, the off-state current was 3 Xl0-9 A/S, which was about 11,500.

The amount of boron added is 1x 10-'A/S for BJ6/SiH< at 4PPM, and 3
/S, 3x10-@A/S was obtained at 12PPI'l. In other words, there is an optimal amount to minimize the off-state current of type (1) semiconductors, and even if it is more than that amount, or less than that amount (but the off-state current becomes large. In particular, if the amount of boron added is 20 PPM or more) As a result, the asymmetry in the V-I characteristics was lost, and the diode characteristics were drastically reduced, especially when a positive voltage was applied.As a result, it was found that it is important that the amount of boron is 20 PPM or less.

Example 2 In the present invention, in Example 1, carbon was simultaneously added to one layer during film formation. That is, 1 in Example 1
During layer formation, BzHi/5iHa = 7PPM.

It was set as 0MS/5iJ-1/80. This distribution is shown in Figure 1 (
Shown in C).

Curve (17) in Figure 2 shows the adhesive characteristics when this layer (1) is 5ixC+-x (O<X4). Then,
It became possible to reduce the off current to 7 Xl0-" A/S, which is about 1/100 of the curve (16). In addition, the on-current was set to 5 to 50 X 10-'^/S, and the liquid crystal at 5 V. It became possible to obtain a suitable current value for driving.The addition of carbon was 0MS/5iHa = 1
If the value is increased to 150, the off-state current can be lowered to the order of 10-s^/S, but if the on-current is increased to 1/10 or more, the on-current becomes 10-s^/S or less, and the liquid crystal The amount of C added is 1710~1/200 (DMS
/ S i Ht) was appropriate.

"Example 3" FIG. 3 shows a circuit diagram using the solid state display device of the present invention.

In the drawing, the picture element (1) is located closer to one electrode (21) (first electrode) of the liquid crystal (3) than the electrode (21) (first electrode) of the composite diode (2).
23) Connected to (third electrode). The composite diode is connected by a second electrode (22) to the X wiring (4), (5) that provides the clock signal. On the other hand, liquid crystal (
The fourth electrode (24) in 3) is the data line (6) of the Y wiring.
, is connected to (7). This X wiring is connected to the same insulating substrate, typically a glass substrate (Fig. 4 (B), (C),
(20) in (o), provided on the liquid crystal (3)
The other fourth electrode (24) ((24) in FIG. 4(B)) is connected to another opposing light-transmitting insulating substrate, typically a glass substrate ((24) in FIG. 4(B), (D)). (20
”)) is provided on the side.

Such picture elements were arranged in a matrix, which was shown as 2×2 in the drawing. This is the same technical concept for a scaled-up display device, for example (100 pixels x 100 pixels).

This embodiment is shown in Fig. 4 as a plan view (A) and longitudinal sectional views (B), (C), (D) at (1.1) in Fig. 1.
)It is shown.

Furthermore, FIGS. 4(B) and 4(C) show vertical cross-sectional views taken along lines B-B' and A-A'' in (A), respectively. In addition, FIG. A vertical cross-sectional view of c' is shown.

The manufacturing method of this element is the same as in Example 1.

That is, a conductive film for the first electrode (21) is formed.

Further, N(12) (I) (13)N(14) is configured according to Example 1 or 2. An upper electrode (15) is formed. Patterning is performed in the X direction by the first mask process.

Next, as shown in FIG. 4, similarly to FIG. 1, a field insulator, here a polyimide resin, is filled around the sides of the laminate, and the top surface thereof and the top surface of the laminate are made approximately the same. Furthermore, CTF is applied on these insulators in close contact with the upper surface of the stack.
is formed to a thickness of 0.1 to 0.3μ. Thus, the third electrode (23) of the liquid crystal display was connected to the second electrode (22). Furthermore, using this CTF as a mask, plasma etching was performed to prevent crosstalk between the leads (3
Do 3).

By using the second mask (1), which performs one overlapping process, the leads (4) in the X direction and the second
The electrode (22), the semiconductor (2), and the upper electrode (-first electrode) (21) of the composite diode could be formed. In addition, both the upper and lower surfaces of this composite diode could be covered with light-shielding chrome without using an extra mask process, and the composite diode could have the characteristics shown in FIG. 2.

Furthermore, the other fourth electrode (24) of the opposing liquid crystal.

Leads (6) were formed as wiring in the Y direction using another first mask (2).

From the above, it is only necessary to use three types of masks to form one active picture element on this surface, and particularly in that case, it has the advantage that only two overlapping masks (one time) are required.

As a display panel, the peripheral circuit (8) shown in Figure 3 will be used.
) and (9) were fabricated as a hybrid configuration by bonding a single crystal IC onto a substrate. Further, another opposing insulating substrate (20') was spaced apart by a width of about 6 to 10 microns, and after the gap was evacuated, a known liquid crystal (3) was sealed.

In this way, it has become possible to pattern an active element type panel using only three masks.

"Effects" As described above, in the present invention, in order to construct a composite diode having V-1 characteristics symmetrical with respect to the origin, boron is added to cancel naturally occurring N-type in one layer. In addition, carbon is added to reduce off-current and improve frequency characteristics. Furthermore, this non-linear element can be applied to liquid crystals used in display elements.
A threshold suitable for the N ratio could be achieved by controlling the amount of boron added to one layer.

Furthermore, since the diode and electrode lead are integrated, patterning can be performed with an extremely small number of masks (three) (overlapping once), and manufacturing yield can be improved.

As for the structural characteristics of the composite diode, P(1)P junction characteristics can be used instead of N(1)N junction characteristics.

However, considering the Stebla-Lonski effect, N(I)
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, it may also be 5ixGe+-x(0
≦X<1).

Although the present invention has characteristics similar to those of conventionally known MIM structures, it can be driven to high frequencies because there is less capacitance component at the interface. This makes it particularly advantageous for large displays (400X 1920). 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, oxygen or nitrogen may be used.

However, since these materials easily become insulators, the amount of addition thereof must be controlled more delicately, and they are more difficult to manufacture than carbon.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view (A) of the composite diode of the present invention. The equivalent circuit (B) and the concentration distribution of boron and carbon added to one layer (C) are shown. FIG. 2 shows the voltage-current characteristics of a conventionally known NIN junction using only amorphous silicon and an N (I)N junction of the present invention. FIG. 3 shows a 2×2 circuit of a display in which the semiconductor elements of the present invention are arranged in a matrix. FIG. 4 shows the structure of one picture element of the display panel of the present invention.

Claims (1)

[Claims] 1. A first non-single crystal semiconductor having one conductivity type, a second non-single crystal semiconductor that is substantially intrinsic due to the addition of boron on the semiconductor, and a second non-single crystal semiconductor on the semiconductor that is substantially intrinsic due to the addition of boron. A semiconductor provided by laminating a first non-single crystal semiconductor and a third semiconductor having the same conductivity type constitutes a nonlinear element having ohmic contact with the first electrode and the second electrode. semiconductor device. 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. 3. A semiconductor device according to claim 1, wherein the second semiconductor is made of a semiconductor having an amorphous structure and containing silicon as a main component to which carbon, oxygen, or nitrogen is added.