JPH0536343A - Circuit breaking switch and manufacture thereof - Google Patents

Abstract

PURPOSE:To miniaturize a circuit breaking switch and make it safe by providing a trench formed with a metal wire, and eccentrically providing a specific shape memory alloy layer in the trench. CONSTITUTION:A resist layer is pattern-formed to mask the left half of the upper face of a deposition layer 3A, and the right half of the deposition layer 3A is removed by anisotropic etching. A shape memory alloy layer 3 is residually formed on the left side face of a trench 2, and a SiN protective film 4 is formed on the whole face of the metal layer 3 except for the adjacent semiconductor board region. Annealing is performed for a preset period at the temperature of the transformation starting point or above of the memory alloy 3 in the inert gas to perform the shape memory treatment of the memory alloy 3. It is then oxidation-treated at the temperature of the transformation starting point or below, the trench 2 grown with a thick oxidation layer 5 is formed, and it is bent and displaced so that the upper section of the alloy layer 3 is closed at the opening section. The oxidation layer 5 is removed to form a metal wiring pattern, then a small and safe switch is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker switch and a method for manufacturing the same. More specifically, the present invention relates to a thermal circuit breaker switch for various semiconductor integrated circuits and a method for manufacturing the same.

[0002]

2. Description of the Related Art A semiconductor integrated circuit, which constitutes various semiconductor memory devices, CPU chips, interface devices, etc., is composed of extremely fine and complicated circuits, and is often liable to be damaged due to external impact or internal physical failure. When a part of the semiconductor integrated circuit is damaged as described above, the load is unbalanced and a partial overcurrent flows to cause heating, which adversely affects the operation of other adjacent elements. In some cases, there was a problem of causing an ignition accident.

Therefore, conventionally, when these semiconductor integrated circuits are used, a current supply / interruption device (relay circuit or the like) for preventing overcurrent has been combined.

[0004]

However, the conventional current supply / interruption device requires an occupation area which is several times or more that of the semiconductor integrated circuit body to be combined, and miniaturization of these semiconductor device products. Was a hindrance to. The present invention has been made under such circumstances, and in particular, it is an object of the present invention to provide a fine thermal switch element that can be formed on a semiconductor substrate that constitutes a semiconductor circuit in order to enable miniaturization of semiconductor products. ..

[0005]

Thus, according to the present invention, the shape memory alloy layer whose upper portion is bent and displaced is provided along one side surface side of the trench formed in the semiconductor substrate, and the bent portion is There is provided a circuit breaker switch which is provided in a biased manner so as to close an opening of a trench and in which a metal wiring is formed on a semiconductor substrate including the trench formation region.

In order to achieve the above-mentioned object, the present invention forms a trench in a semiconductor substrate region in which a metal wiring is to be formed, and a specific shape memory alloy layer is deviated in the trench to provide a mechanical thermal sensitivity. This means that a switch is constructed. The circuit break switch of the present invention is, for example,
After forming a trench in a silicon semiconductor substrate and burying a shape memory alloy in the trench, the buried layer on one side surface of the trench is vertically removed by etching, and the shape memory alloy is formed on the other side surface of the trench. After the layer is left and the shape of the shape memory alloy layer is memorized, a region adjacent to the shape memory alloy layer is selectively oxidized to grow a thick oxide film to form a shape memory alloy layer. It can be manufactured by bending and displacing the upper part, then removing the thick oxide film, and then performing a process for forming a metal wiring on the semiconductor substrate including the trench formation region.

The trench can be formed according to a method of forming a so-called trench capacitor or the like. In addition, the selective oxidation of the substrate is performed by the so-called LOC.
According to the OS method, the SiN-based protective film can be used as a mask.

[0008]

When the substrate is overheated due to the overcurrent flowing through the metal wiring and the temperature exceeds the transformation temperature of the shape memory alloy, the upper portion of the shape memory alloy layer returns to the state before displacement. Therefore, the metal wiring formed on this upper surface A crack will occur in the wire and the line will be cut off, and the current will be cut off to prevent overheating.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A process for manufacturing a circuit breaker switch according to an embodiment of the present invention will be described below with reference to the accompanying drawings. First, as shown in FIG. 1, a trench 2 having a diameter of about 3 μm and a depth of about 5 μm is formed in a power supply circuit region of a silicon semiconductor substrate 1 by known photolithography, and then a shape memory alloy material is deposited on the entire surface and etched back. By doing so, the buried layer 3A of the shape memory alloy was formed in the trench 2. As this shape memory material, for example, Ti-Ni is used.
Examples thereof include a system alloy and a Ti-W alloy, and for example, they can be deposited and grown by the CVD method.

Next, after patterning a resist layer so that the left half of the upper surface of the deposited layer 3A is masked, the right half of the deposited layer 3A is removed by anisotropic etching, as shown in FIG. The shape memory alloy layer 3 was left on the left side surface of the trench 2. Then, FIG.
As shown in FIG. 3, after the SiN-based protective film 4 is formed on the entire surface of the shape memory alloy layer 3 except the surface region of the adjacent semiconductor substrate by the CVD method and the lithography, an inert gas (Ar
In a gas) at a temperature above the transformation start point of the shape memory alloy (about 720 ° C. in this example) (about 800 ° C. in this example)
The shape memory alloy layer 3 was memorized for the shape by annealing for 1 hour.

Thereafter, the temperature (70
By oxidizing at 0 ° C.) to grow a thick oxide layer 5 (2 μm) as shown in FIG. 4, the upper portion of the shape memory alloy layer 3 in the trench is bent so that the opening of the trench is closed. It was displaced. After that, the oxide layer 5 is removed by etching, and the wiring (for example, Al, Al-Si
And the like) was formed to obtain the circuit breaker switch of the present invention shown in FIG.

In such a circuit breaker switch, when the temperature rises above the transformation start point due to overcurrent or the like, the upper portion of the shape memory alloy layer 3 restores to its original shape, and as shown in FIG. The metal wiring pattern 6 breaks and becomes a broken state, whereby the current is interrupted and overheat is automatically prevented, thereby functioning as a micro switch.

In the above embodiment, the circuit breaker switch is formed on the same semiconductor substrate that constitutes the semiconductor integrated circuit. However, as an independent switch element formed on another substrate, an integrated circuit substrate and an integrated circuit substrate are used. It may be configured by connecting with a bonding wire or the like.

[0014]

According to the present invention, it is possible to provide a microminiature thermal circuit breaker switch by combining a minute trench and a shape memory alloy layer. Therefore, by attaching to various semiconductor integrated circuits, it is possible to provide a safe integrated circuit element without increasing the size of the device.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing one step of a manufacturing process of a circuit breaker switch of the present invention.

FIG. 2 is an explanatory view showing the next step similarly to FIG.

FIG. 3 is an explanatory view showing the next step similarly to FIG.

FIG. 4 is an explanatory view showing the next step similarly to FIG.

FIG. 5 is a structural explanatory view showing an embodiment of the circuit breaker switch of the present invention.

FIG. 6 is an explanatory diagram showing the same operation.

[Explanation of symbols]

 1 Silicon Substrate 2 Trench 3 Shape Memory Alloy Layer 3A Buried Layer 4 SiN System Protective Film 5 Oxide Layer 6 Metal Wiring Pattern

Claims (2)

[Claims] 1. A shape memory alloy layer whose upper portion is bent and displaced is provided along a side surface of a trench formed in a semiconductor substrate, and the bent portion closes an opening of the trench. A circuit breaker switch, which is provided in a column and has metal wiring formed on a semiconductor substrate including the trench formation region. 2. A trench is formed in a semiconductor substrate, a shape memory alloy is buried in the trench, and a buried layer on one side surface of the trench is vertically removed by etching to the other side surface of the trench. After the shape memory alloy layer is formed and the shape of the shape memory gold layer is memorized, a region adjacent to the shape memory alloy layer is selectively oxidized to grow a thick oxide film. A method for manufacturing a circuit breaker switch, which comprises bendingly displacing an upper portion of an alloy layer, then removing the thick oxide film, and then performing a forming process of a metal wiring on a semiconductor substrate including the trench forming region.