JPS6059594A - Semiconductor memory device - Google Patents

Abstract

PURPOSE:To obtain a non-contact type non-volatile semiconductor memory device optically reading out data by using the change of the electric conductivity of a semiconductor by decreasing or increasing the electric conductivity of a prescribed amorphous semiconductor by irradiated light having different wavelength to write/erase information. CONSTITUTION:The amorphous semiconductor 1 consisting of silicon, germanium, etc. including oxygen and hydrogen is formed between electrodes 3, 2 laminated on an insulating substrate 4 to form the non-volatile semiconductor memory device. When a computer 32 irradiates light of short wavelength of 500nm or less from a light source 35 at a specified address position, the electric conductivity of the semiconductor 1 is reduced and irradiation of long wavelength light of 1mu or more increase the electric conductivity. The errasion for writing and reloading of information is executed by the reversible electric conductivity change. The written information is read out contactlessly on the basis of the change of electric resistance at the light irradiation on a position corresponding to the address through electrodes 2, 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor memory device for constructing a nonvolatile optical memory using a non-single crystal semiconductor including an amorphous structure.

This invention is a non-single crystal semiconductor mainly composed of germanium or silicon to which hydrogen and oxygen are added,
The process of writing memory by reducing the electrical conductivity of this semiconductor by irradiating short wavelength light of 00 nm or less, and conversely, the process of irradiating with short wavelength light of 1μ or more (~50/7) or 120 to 300°C
The present invention proposes a rewritable non-volatile semiconductor memory device having a heat treatment to increase the electrical conductivity of the semiconductor (2) and a culm for rewriting memory.

This invention is based on the conventional Stebla-Lonski effect (light irradiation effect).
The idea is to create a rewritable memory device by making use of the decrease in electrical conductivity due to light irradiation, which is known as a decrease in electrical conductivity, which is the worst deterioration decrease in general semiconductor devices, especially photoelectric conversion devices. It is a feature. That is,
Conventionally, it has been known that when a photoelectric conversion device or the like is manufactured using amorphous silicon, the photoelectric conversion device deteriorates due to light irradiation and its electrical conductivity decreases. As a result of detailed investigation by the present inventor into this factor, it was found that in group Ⅰ non-single crystal semiconductors whose main components are silicon and germanium, recombination centers exist in the forbidden band (hereinafter referred to as "within Eg") of the energy hand (hereinafter referred to as "Eg"). It was found that this is caused by an increase or decrease in density (hereinafter referred to as RC). Furthermore, in this semiconductor, for example, a silicon semiconductor,
We were able to demonstrate that oxygen and hydrogen form 01121 (which bonds with the silicon dangling bond3) or separate, increasing or decreasing the number of recombination centers.

As a model, Nol Si II""Si \/ Si ---0・Si (110) #0 (11-)
I11] has been proposed. That is, the D6 level changes to 1)- or D+ by irradiation with short wavelength light. That is, the reaction changes to the left in the above equation. As a result, a deep RC is formed within Eg. This RC reduces electrical conductivity. However, Il-, 11F reversibly changes to Do by far-infrared light or heat treatment. The present invention actively utilizes the property that RC reversibly increases or decreases.

Therefore, the intrinsic semiconductor or substantially intrinsic semiconductor of the present invention ('1i conductor doped with P or B at a concentration of 1x1018 CI11-3 or less, hereinafter referred to as a single layer in fl'I or a ■-type semiconductor) , oxygen and hydrogen actively (4
) is added. Specifically, oxygen is 1X1020~3X
10'' cm-3, e.g. lXl0'' cm-y, and hydrogen was included in an amount of 5 to 30 atom %, e.g. 15 atom %.

In the present invention, in order to read out the stored information, the magnitude of this electrical conductivity is determined by angle-viewing light of a specific intensity to a specific address (
100~10000lx) 1~100μφ e.g. 5
1 diameter spot, for example Ar laser (5) 4.5 layer m
+48Flnm), 1le-Nc laser (632,
rOJ is read out as "1" based on the magnitude of the electrical resistance of the address.

That is, in the semiconductor device of the present invention, the first and second
The electrode is a surface electrode, and electric energy is applied to the entire surface of this semiconductor. However, in order to specify the address, light irradiation is applied to the predetermined address in the form of a spot (1 to 100 μφ, for example, 5
μφ), and the sensitivity of the electrical conductivity at that address is 102 to 1 compared to other areas (areas of the disk where light irradiation is not performed).
09 times.

By checking the electrical conductivity at that location, it was possible to read the memory at any address. With such a configuration, it has become possible to create a nonvolatile memory that can read out electrical signals by a(5) irradiation with light. For this reason, this light suboso 1-
By reducing the size of 1 to 10” Ghi
t memory, and it has great application in optical disks.In particular, it is made of silicon, which is inexpensive, and is not a polluting material, and does not use expensive materials such as tellurium oxide or for magneto-optical disks. It has the great advantage of being able to achieve lower costs and higher reliability.

Furthermore, the writing of memory in the semiconductor memory device of the present invention is 5
Short wavelength light of 00 nm or less, such as nitrogen laser (337r
+m) was irradiated onto a predetermined address with a spot of 1 to 100 μφ, and the initial address “O” was selectively changed to “11”. Furthermore, in order to rewrite the memory, it was possible to stably create "0" by thermal annealing at 120 to 300 DEG C., for example, at 180 DEG C. for 30 minutes, to make all "0" on this disk. Also, to rewrite selectively, set 700.
Long wavelength light of r+m or more (1 to 3011, preferably 10.
Annealing can be performed by irradiating a beam of 8μ) to locally heat only a predetermined address. Write (6) 1. It has the feature that writing and rewriting of a can be performed only by light irradiation, and large-capacity processing is possible.

The present invention proposes a non-contact type semiconductor memory device that makes optical reading possible by utilizing the increase and decrease in electrical conductivity of semiconductors.

The contents are described below in the drawing.

Figure 1 shows a transparent conductive film (C) on a transparent insulating substrate (4).
The electrode (3) (hereinafter referred to as "TO") is made of a two-layer film consisting mainly of tin oxide to which a halogen element is added, and indium oxide (hereinafter referred to as "TO") to which 10% by weight or less of tin oxide is added, and tin oxide. It was formed selectively (called El). Furthermore, a first non-single crystal semiconductor (here, P type) (5
) and a second non-single crystal semiconductor (here I type) (6) and a third non-single crystal semiconductor (here N type) (7) to form a semiconductor having a PIN structure (1>(S El (3) configured with a counter electrode (2) (hereinafter referred to as E2) of a second electrode having transparent light-transmitting properties such as ITO.
-5(1)-E2 (2) A vertical cross-sectional view of the structure is shown.

(7) In the drawing, the semiconductor (1) is first made of silane (S-II
A plasma glow discharge method (P
CVD method), optical plug V 0.1 to 10 by CVD method
For example, it is formed to have a thickness of 3μ. In the drawing, the first semiconductor (5) is of P type, C1k/ (Sil14+ cl
10, 2 to 0.7 For example, set B to BL at the same time as 0.5
II, etc. from 10” to ]0”cm-yo e.g. B z
I&/SI II) -0.5% was added to make 5jxC+-x O<x<l x=0.8.

Further, the third semiconductor is N type, and C119/(S i
It, +C1ψ-0,05~0.5 e.g. 0.1 and at the same time P as P II.

For example, PI et al/5i
ll, = 1% to form P in the semiconductor (1).
An IN junction was constructed.

Is this semiconductor film made by sputtering, vacuum evaporation, or optical plug?
CVD method, 1. T (low temperature) CVD method (IIOMOCV
Alternatively, a low pressure CVD method (also referred to as D method) may be used.

Furthermore, in the process of about 1 unit before and after forming this semiconductor, transparent electrodes (3>, <2) are formed by a known vacuum evaporation method, plasma CVN method, or reduced pressure CVN method to obtain the structure shown in FIG. Obtained.

(8) An energy band diagram corresponding to the structure shown in FIG. 1 is shown in FIG.

In this energy band diagram, electrons (19) flowing in the conduction band (11) of the ■-type semiconductor (6) and valence band (12)
What is the hole (18) flowing through the l? which exists in the ■-type semiconductor (6)? c (13).

This rrc occurs and disappears due to the above-mentioned light irradiation effect, and Rrc is caused by unpaired bonds in silicon that do not change.
There is C. However, when this RC (17), <B) increases, electrons and holes recombine (13), resulting in poor electrical conductivity. This change in electrical conductivity is
As shown in the figure.

In the drawings, "1" indicates high electrical conductivity due to thermal annealing, and "0" indicates low electrical conductivity due to irradiation with short wavelength light. Furthermore, the curve (13) is the dark conductivity, and the curve (13) is the dark conductivity.
5) is the optical conductivity of (100 mW/cj). (14) shows the electrical conductivity when irradiated with light using an argon laser. Furthermore, as is clear from the drawing, (4
4) and <45) have Id "1" and [o-1 when read (9), respectively, and it can be seen from their reversible change that writing is possible.

This figure 1 shows the case of amorphous silicon, but Ge,
Similarly, reversible changes can be made in non-single crystal compounds or mixture semiconductors such as GexSil-x (0<x<1).

It goes without saying that the term "semiconductor" as used in the present invention includes semi-insulators to the extent that current can flow therethrough.

In addition, in the present invention, when high voltage pulsed light is applied,
In FIG. 1, electrode (2) t(3) and semiconductor (5), <
Reactions at the interface with 7) also occur during long-term use, forming insulating silicon oxide at the interface, resulting in deterioration of characteristics. Therefore, the semiconductor (5), < 7) is 5ixC1-
><(0< x < 1) to improve reliability.

That is, the electrode (3) whose main component is tin oxide, P-type Six
C1-x O< x < 1 x = 0.8 (100
~500 people (200 people per row) - Type I Sl (Si
: O: HO, 1-3 Me1 e.g. 0.5 p)
-N-type Si (500 people ~ 1μ e.g. 0.2(10) /7) -N-type SixC1-x (0< x < 1
x = 0.9) (100 to 500 people, for example 200 people)
--The structure of the electrode (2) was made mainly of ITO. By creating a heterojunction in terms of energy band,
It was possible to prevent the generation of insulating silicon oxide at the interface between the electrode and the semiconductor at a high temperature of 150 to 300°C, and high reliability was achieved.

Embodiment 1 This embodiment, whose outline is shown in FIG. 4, is a non-volatile light-emitting memory of an optical readout type ROM in which an opto-electrical program can be rewritten. This optical memory is extremely effective when used as an optical memory disk for office automation and can be programmed arbitrarily.

That is, in FIG. 4, (A) shows memory writing;
(B) shows reading. In the drawings, insulating substrate (4) such as glass, ceramic, organic film, <100-5
The first conductivity type electrode (3) is coated with a reflective electrode (e.g. aluminum) (9), CTO (e.g. tin oxide) (8) with a thickness of 0.5 (11) to 1 μm). Furthermore, a non-single crystal semiconductor (1) mainly composed of silicon with oxygen and hydrogen added in one layer and having a PIN junction as described above was formed to a thickness of 0.7 mm.
It was formed to a thickness of μ. Further above it is the CTO of rTO.
(2) was formed on the entire surface. This substrate has a disk shape similar to that of a record slope. The address is controlled by a microcomputer (32) and the nitrogen laser beam (35) is emitted.
(emission wave length: 337 nm) was irradiated from a light emitting source (35), and the beam diameter was set to 1 to 100 μΦ, for example, 5 μΦ. The short wavelength ultraviolet light of 500r+m or less is
By applying at an intensity of 00 mW/cd, a recombination center was generated and the electrical conductivity was "0" in FIG. Thus, for example, "0" was written in (24>, <26). As a result, the other address (25) became Ill.

This memory was written on the entire board with a sterilizing light (2537 people)
Alternatively, a CO laser (waveguide type) may be used to irradiate far-infrared light of 10.6μ to make the specific region 11”.

This method has the advantage that it is possible to shift the noise mask (12) in the direction of −1 during reading.

Memory reading is shown in Figure 4 (B), where a weak (strong within the range where the stored information does not change) light irradiation is applied to a predetermined address using an argon laser (488 nm, 515n><33).
was specified by irradiating the address to be read. The address was input into the computer (32), and an electric pulse (29) was applied in synchronization with the signal. Then, the information of the detection address irradiated with light is detected by the resistor (26) (31)
did.

This time chart is shown in FIG.

That is, FIGS. 5A and 5B show the writing of memory.

High-resistance regions (44), <46) are selectively formed in a part of the optical disk by intense light pulse irradiation (47), <48).
is formed as shown in FIG. 5(B). (44>, <4
5), <46) are (24>, (2) in Figure 4(A)
5>, <26).

Also, readout is shown in Figure 5 (c) and <D), but voltage (29) is applied in synchronization with the light, and the output potential is as shown in Figure 5 (D). , <39
) could be obtained as follows.

(13) In other words, this optical memory (program ROM') uses light to make a part of a record-like disk into a high-resistance region or a low-resistance region, and conversely to make the other part a relatively low-resistance region or a high-resistance region. In addition, address designation is performed using light in a non-contact manner, and readout is performed by electrical conduction, making contactless photoelectric readout possible. Therefore, it was possible to create a rewritable ROM with so-called photoelectric writing. The principle of the present invention is completely different from conventionally known non-rewritable optical disk memories which are formed by selectively removing a portion of a substrate. Furthermore, it has been found that the stored information can be rewritten and is nonvolatile, making it ideal as a large-capacity optical disk memory.

As is clear from the above explanation, the present invention creates a non-volatile memory by adding a large amount of impurities such as hydrogen and oxygen to amorphous silicon and controlling the reversible change in electrical conductivity. It is also effective to increase the contrast of rOJ rlJ(]4) by using not only one PN junction but also a PNIPN junction, which is an embodiment of providing it in a semiconductor, and furthermore, there are many applications based on the same technical idea. is possible.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a semiconductor device using an N junction of the present invention. FIG. 2 is an energy band diagram for explaining the present invention in detail. FIG. 3 shows the change characteristics of electrical conductivity of a non-single crystal semiconductor. FIG. 4 shows an embodiment of the semiconductor memory device of the present invention. Figure 5 shows the time chart 1-- used in the embodiment of Figure 4.
shows. Patent applicant (15) Gi1 Tomoe'I O/ O/ JJ-JJ Hino 3rd

Claims (1)

[Claims] 1. A non-single crystal semiconductor having an intrinsic or substantially intrinsic non-single crystal semiconductor on a first electrode made of a conductive layer on a conductive substrate or an insulating substrate; A semiconductor device including a second electrode on a crystalline semiconductor, and at least one of the first and second electrodes having a light-transmitting property,
A semiconductor memory device comprising: a first step of reducing the electrical conductivity of the semiconductor; and a second step of increasing the electrical conductivity of the semiconductor. 2. A semiconductor memory device according to claim 1, wherein the memory information of the address is read by determining the degree of electrical conduction of the address irradiated with light from the first or second electrode side. 3. In claim 1, the electrical conduction of a semiconductor is reduced (1) by irradiation with short wavelength light of 500 nm or less, and the long wavelength light of 1 μ or more or 120 to 30
A semiconductor memory device characterized in that memory writing and rewriting are performed by increasing electrical conduction through thermal annealing at a temperature of 0° C. or higher. 4. In claim 1, the non-single crystal semiconductor mainly contains silicon or germanium, and further contains 1 x 1020 to 5 x 10" cm of oxygen and 1 to 5 x 10" cm of hydrogen.
A semiconductor memory device characterized by containing 30 atomic %.