JPS60211698A - Read only memory device - Google Patents

Abstract

PURPOSE:To obtain a large capacity ROM which is easily manufactured and can store data in the vertical direction by reading out electroacoustic-optically the presence or absence after a memory cell having the presence or absence of the prescribed micro area in a single crystal is provided. CONSTITUTION:A memory cell 2 having the presence or absense of a micro lattice distortion area with a dislocation 3 where a lattice constant is partially different in a single crystal 1 is integrated and formed, and the contents stored in the cell 2 are electrically read out in accordance with the presence or absense of a reflected wave accompanying ultrasonic wave radiation caused by an electrode 4 and a piezoelectric material 12 provided on the crystal. With this constitution the storage in the vertical direction can be performed due to lamination of the single crystal, and a large capacity ROM which can be easily produced and has little of masking process can be obtained accordingly.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a read-only storage device having a novel configuration with high density and large capacity.

Conventional configurations and their problems Storage devices play an important role in information processing in electronic computers and data communications, but in order to expand their application range and capabilities, it is necessary to increase the amount of storage and storage. ing.

In principle, a read-only storage device maintains two stable states in a storage cell consisting of a large number of aggregates, and distinguishes between two logical values of the stored state in any specified storage cell. , which can be reproduced as a signal to the outside.

Semiconductor storage devices are currently widely used as main memories, and with the development of semiconductor integrated circuits, they are becoming faster, more highly integrated, and have a larger capacity.

FIG. 1 shows a read-only memory (R) of a semiconductor memory device.
ead 0nly Memory: ROM) (7))
-914, which is called a mask ROM. The configuration of this memory is such that a two-dimensional matrix is created by word line A and digisodo line B, and the presence or absence of connection of the coupling elements of both lines is stored as binary information. A bipolar element is used as the coupling element, and those whose emitters are connected represent "1" and those whose emitters are not connected represent "o". Writing information on whether or not there is a connection is determined by a photomask during manufacturing. This mask R
Since the formation of OM uses semiconductor integrated circuit technology,
High speed, high density.

There are problems with whether it is possible to increase the capacity, and the manufacturing process for forming the element is complicated and costs are high.

Furthermore, each memory cell has a single-layer element, so it has a capacity of only one bit, and it is not possible to record multiple bits in the vertical direction.

OBJECTS OF THE INVENTION The present invention aims to eliminate the above-mentioned drawbacks and to provide a read-only storage device of a new construction, which allows vertical recording.

Structure of the Invention The present invention comprises a memory cell that is provided with a single crystal to detect the presence or absence of a microlattice strain region with locally different lattice constants, and an electroacoustic transducer element formed on the cell surface to acoustically detect the presence or absence of a microlattice strain region. This is a read-only storage device configured to detect and read out using reflected waves of plane waves.

DESCRIPTION OF THE EMBODIMENTS FIG. 2(a) is a structural diagram showing an embodiment of the memory cell of the present invention. Memory cells 2 divided into a single crystal 1 are assembled, dislocations 3 are arranged in each memory cell, and the presence or absence of dislocations is written as binary information.

FIG. 2(b) is a cross-sectional structural diagram showing a configuration for reading information in a memory cell. A piezoelectric material film 4 is placed on each memory cell 2.
and electrodes 5 are formed to constitute a piezoelectric vibrator. When a pulse voltage is applied to the electrode 6 and ultrasonic waves are applied to the crystal from the piezoelectric vibrator, reflected waves due to the dislocations are read out as output signals from the memory cells with dislocations, and waves reflected from the dislocations are read out as output signals from the memory cells without dislocations. is not output. Reflected waves are generated when there are microlattice strain regions in a single crystal where the lattice constants are locally different, so a similar phenomenon can be obtained with lattice defects such as point defects in addition to dislocations. It is also possible to use impurity atoms with different lattice constants.

Next, FIG. 3 shows a circuit diagram showing a configuration for reading a designated address of a memory cell. A two-dimensional matrix is created with word lines X and digit lines Y, and electrodes 6 of a piezoelectric vibrator are connected to each line.

By driving a pulse voltage from a designated word line, information in a memory cell at a designated address can be read from a designated digit line.

Next, we will explain how to write dislocations into memory cells in Figures 4(a) to 4(a).
Shown in (C). A charged particle beam 8 is incident on the surface of a memory cell in a single crystal T to form a damaged region 9 on the crystal surface. The charged particles are electrons, ions, etc. (2L). Next, as shown in (b), an Ehitakinoyal layer 10 is grown from the surface of the single crystal. In this case, appropriate heat treatment may be applied. As a result, dislocations 11 occur in the area where the charged particles were incident.
grows. Next, as shown in (C), a piezoelectric material 12 and an electrode material 13 are formed on the surface of the memory cell and patterned by photoetching.

In the above embodiment, there is information of 1 bit, /) in the memory cell, but as shown in FIG. By arranging dislocations in each layer, the number of bits written in one memory cell can be increased. The output is read out as a time series pulse signal corresponding to bit information. As shown in (b), since the amplitude of the pulse signal is attenuated, the maximum number of bits that can be written is determined by a value equal to or higher than the threshold value at which the pulse height can be discriminated.

In the case of this example, the dimensional constraints are determined as follows. Assuming that the width of the piezoelectric vibrator is equal to the width of the piezoelectric vibrator and the depth of the dislocation is -iL, it is necessary to satisfy the following plane wave condition: D>10+L Old... (1). On the other hand, as a condition for a dislocation to interact with an incident wave, if the wavelength of the incident wave is λ, then λ is □1.
...(2) becomes. Therefore, the natural frequency f of the piezoelectric vibrator is f=r〉1
o−τ pa...(3) is required to be satisfied. Here, V is the speed of sound in a single crystal.

In the case of silicon single crystal, if v-80oo@,,'s is formed with L=1/jfi as the dislocation depth, then f>80G
Hz. The access time is t=-=100 ps6c if the delay in electro-phonic conversion of the piezoelectric vibrator is ignored. The width of the piezoelectric vibrator is D) 10μm, and the memory cell size in this case is 10Cμyt.
? becomes.

Effects of the Invention According to the present invention, (1) The number of mask steps is small, and manufacturing costs can be reduced.

(2) Since the manufacturing process can be carried out without using ordinary semiconductor integrated circuit technology, it is possible to increase the capacity and achieve high throughput.

(3) A large number of pips can be recorded in the vertical direction in one memory cell, and high density recording is possible.

It has the following effects and is of high industrial value.

, 4. Brief Description of the Drawings FIG. 1 is a diagram showing the configuration of a conventional semiconductor memory device, FIGS. 2(a) and (b) are diagrams showing an example of the memory cell configuration of the present invention, and FIG. A circuit diagram of a memory device according to the present invention, FIGS. 4(2L) to (C) are cross-sectional views of the process of forming a memory cell of the present invention, and FIG. A cross-sectional view of the memory cell, FIG. 5(b) is similar to FIG. 5(a).
FIG. 3 is a diagram showing pulses when reading out a memory cell of FIG.

1.7...Single crystal, 3,11...Dislocation, 4゜12
...Piezoelectric material, 5,13... Electrode.

Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 l゛° ・・0・′ Figure 3 Y Figure 4

Claims (3)

[Claims] (1) A plurality of memory cells each having micro lattice strain regions with locally different lattice constants in a single crystal, and an acoustic plane wave being incident into the memory cells to create micro lattice distortion regions within the memory cells. A read-only storage device comprising an electroacoustic transducer that detects the presence or absence of a reflected wave. (2) A storage device exclusively for indexing according to claim 1, characterized in that a plurality of micro lattice strain regions having locally different lattice constants are distributed in the vertical direction in the single crystal. (3) The read-only storage device according to claim 1 or 2, wherein the micro lattice strain regions having locally different lattice constants are formed by dislocations in the single crystal.