JPS6072263A - Writing system for insulation breakdown type memory - Google Patents

Abstract

PURPOSE:To enable the reduction in the write voltage by a method wherein a positive voltage is impressed on the Al electrode side, in the titled device having an Si oxide layer, a poly Si film, its oxide film, and the Al electrode on the surface of a substrate. CONSTITUTION:A P type semiconductor diffused layer 2 is provided on the N type semiconductor substrate 1, and an N type semiconductor diffused layer 3 is provided in the layer 2. The Si oxide layer 4, poly Si film 5, and its oxide film 6 are provided thereon, and further the Al electrode 7 is provided. With the electrode 7 side as the positive side, a voltage is impressed by means of a power source 9 in order to utilize the semiconductor device of this construction as the titled device. This system enables the reduction in the breakdown voltage and the decrease in the strength of electric field. In other words, this system can reduce the write voltage for the titled device.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a writing method for a semiconductor memory device, and in particular to a write method for a semiconductor memory device.
The present invention relates to a write method for a dielectric breakdown type memory that utilizes dielectric breakdown of a polysilicon oxide film used as a ROM (programmable memory).

Prior Art and Problems FIG. 1 is a diagram showing a cross section of a conventional dielectric breakdown type memory (hereinafter referred to as BIC memory) and the power source of the voltage applied thereto, and FIG. 2 is an equivalent circuit diagram thereof. As is conventionally known, in this structure, a P-type semiconductor diffusion layer 2 is provided on an N-type semiconductor substrate 1, an N-type semiconductor diffusion layer 3 is provided in the P-type scattering layer 2, and a silicon oxide layer is formed on top of the N-type semiconductor diffusion layer 3. A layer of (SiO,) 4, a doped polysilicon film 5 having a thickness of 4000 to 5000 Å, and an oxide film 6 of the polysilicon film 5 are provided, and an aluminum electrode 7 is further provided as an electrode.

Conventionally, in order to use it as a BIC memory, a power supply 8 is provided that applies a voltage with the polarity shown in the figure, and the polysilicon oxide film 6 is heated by gradually increasing the negative applied voltage.
A method has been used to use it as a memory by causing dielectric breakdown.

As shown in the circuit diagram in Fig. 2, if the NP junction part is equivalently represented by a diode 21, the polysilicon part is equivalently represented by a parasitic resistance 22, and the polysilicon oxide film is equivalently represented by a capacitor 23. 1 indicates that the polarity of the voltage applied to the power supply 8 is applied in the forward direction to the diode 21.
However, as is already known, the impact ionization of diodes tends to be quite high for positive applied voltages, which causes the problem that the write voltage to the memory becomes considerably high. was there.

OBJECTS OF THE INVENTION An object of the present invention is to provide a write method for a dielectric breakdown type memory that can lower the dielectric breakdown voltage of a polysilicon oxide film in the dielectric breakdown type memory, that is, it is possible to lower the write voltage 1 voltage. .

Structure of the Invention According to the present invention, a P-type semiconductor diffusion layer is provided on an N-type semiconductor substrate, an N-type semiconductor diffusion layer is provided in the P-type semiconductor diffusion layer, and a silicon oxide layer and a polysilicon layer are formed. In a writing method for storing data in a dielectric breakdown memory composed of a film, its oxide film, and an aluminum electrode, a single write method of the dielectric breakdown memory is characterized in that a positive voltage is applied to the aluminum electrode side. This is achieved by providing the following.

Embodiment FIG. 3 is a diagram showing a write method of a dielectric breakdown type memory according to the present invention. In FIG. 3, each component (1 to 7) constituting the dielectric breakdown type memory is exactly the same as the conventional type shown in FIG. The feature is that the voltage is applied with the voltage on the positive side.

FIG. 4 is an electrical equivalent circuit diagram of FIG. 3, and as mentioned above, the NP junction part is isometrically connected to a diode 21, the polysilicon part is isometrically connected to a parasitic resistor 22, and the polysilicon oxide film is connected isometrically to the diode 21. Isometrically representing the capacitance 23 indicates that the polarity of the voltage applied by the power source 9 is applied in the opposite direction to the diode 21.

5 and 6 are graphs showing the effects of the writing method according to the present invention. In Figure 5.6, the horizontal axis shows the thickness T of the polysilicon oxide film at each temperature, and the vertical axis shows the breakdown voltage (yolt) V at which dielectric breakdown occurs; Electric field strength (MY^)S is shown. The dotted line shows the conventional method and shows the case where a negative voltage is applied to the aluminum electrode side, and the solid line shows the method according to the present invention and shows the case where a positive voltage is applied to the aluminum electrode side. As is clear from the graph, the method according to the present invention can lower the breakdown voltage at each thickness T of the oxide film 6 than the conventional method, and also lowers the electric field strength. That is, the method of the present invention can lower the write voltage to the BIC memory.

Effects of the Invention According to the present invention, the dielectric breakdown voltage of the dielectric breakdown type memory can be lowered, so that the write voltage can be lowered.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the conventional 1-input method, Figure 2 is an equivalent circuit diagram of Figure 1, Figure 3 is a diagram showing a writing system based on "unfired", and Figure 4 is an equivalent circuit diagram of Figure 3. , and FIGS. 5 and 6 are graphs showing the effects of the writing method according to the present invention. (Explanation of code) 1ma, N vertical? b Dobukuro 2...P type semiconductor diffusion layer 3...N type semiconductor diffusion layer 4...Silicon oxide 5...Polysilicon film 6...Polysilicon oxide film 7...Aluminum electrode 8.9... Power supply 21... Equivalent diode 22... Equivalent resistance 23... Equivalent capacitance Patent applicant Fujitsu Limited Patent application representative Patent attorney Akira Aoki Patent attorney Kazuyuki Nishitate Patent attorney Yukio Uchida Patent Attorney Akira Yamaguchi Figure 1: Figure 2 Figure 3 Figure 4 Figure 5 850850900900 (0C) 6 Figure 850850 (6) 9 Kasumi (0C)

Claims (1)

[Claims] 1. A P-type semiconductor diffusion layer is provided on an N-type semiconductor substrate, and an N-type semiconductor diffusion layer is provided in the P-type semiconductor diffusion layer, and a silicon oxide layer, a polysilicon film, the oxide film, and an aluminum electrode are formed. A method for writing data into a dielectric breakdown type memory constructed as described above, characterized in that a positive voltage is applied to the aluminum electrode side.