An operation method of a multi-bits read only memory includes a step of applying a gate voltage to a conductive gate, a first voltage to a first electrode, and a second voltage to a second electrode. The multi-bits read only memory of the present invention includes a substrate and a transistor structure with the conductive gate mounted between the first electrode and the second electrode, a first oxide located between the first electrode and the conductive gate, and a second oxide located between the second electrode and the conductive gate. The present invention creates an initial state wherein the transistor structure is not conducting, an intermediate state wherein the first oxide is punched through by the first voltage, and a fully opened state wherein both the first oxide and the second oxide are punched through. The aforementioned states allow storage of multiple bits on the read only memory.

A one-time programmable (OTP) memory cell includes a substrate comprising an active area surrounded by an isolation region, a transistor disposed on the active area, and a diffusion-contact fuse electrically coupled to the transistor. The diffusion-contact fuse includes a diffusion region in the active area, a silicide layer on the diffusion region, and a contact partially landed on the silicide layer and partially landed on the isolation region.

A bit cell structure for one-time programming is provided in the present invention, including a substrate, a first doped region in the substrate and electrically connecting a source line, a second doped region in the substrate and having a source and a drain electrically connecting a bit line, a heavily-doped channel in the substrate and connecting the first doped region and the source of second doped region, and a word line crossing over the second dope region between the source and the drain.

A memory device includes a transistor, an anti-fuse element, a first gate via, a second gate via, and a bit line. The transistor includes a fin structure and a first gate structure across the fin structure. The anti-fuse element includes the fin structure and a second gate structure across the fin structure. The first gate via is connected to the first gate structure of the transistor and is spaced apart from the fin structure in a top view. The second gate via is connected to the second gate structure of the anti-fuse element and is directly above the fin structure. The bit line is connected to the fin structure and the transistor.

A resistive random-access memory cell includes a well region, a first doped region, a second doped region, a third doped region, a first gate structure, a second gate structure and a third gate structure. The first gate structure is formed over the surface of the well region between the first doped region and the second doped region. The second gate structure is formed over the second doped region. The third gate structure is formed over the surface of the well region between the second doped region and the third doped region. A first metal layer is connected with the first doped region and the third doped region. A second metal layer is connected with the conductive layer of the first gate structure and the conductive layer of the third gate structure.

A one-time programmable (OTP) memory cell includes a substrate comprising an active area surrounded by an isolation region, a transistor disposed on the active area, and a diffusion-contact fuse electrically coupled to the transistor. The diffusion-contact fuse includes a diffusion region in the active area, a silicide layer on the diffusion region, and a contact partially landed on the silicide layer and partially landed on the isolation region.

A one-time programmable (OTP) memory cell includes a substrate comprising an active area surrounded by an isolation region, a transistor disposed on the active area, and a diffusion-contact fuse electrically coupled to the transistor. The diffusion-contact fuse includes a diffusion region in the active area, a silicide layer on the diffusion region, and a contact partially landed on the silicide layer and partially landed on the isolation region.

A semiconductor structure includes a substrate, first and second transistors, first and second fuses, a contact structure, and a dielectric layer. The substrate has first and second device regions, and a fuse region. The first and second transistors are respectively above the first and second device regions. The first fuse is electrically connected to the first transistor and includes a first fuse active region having first and second portions. The second fuse is electrically connected to the second transistor and includes a second fuse active region having third and fourth portions. The contact structure interconnects the second portion and the third portion, wherein the first portion and the fourth portion are on opposite sides of the contact structure. The dielectric layer is between the contact structure and the fuse region of the substrate.

A semiconductor structure includes a substrate, first and second transistors, first and second fuses, a contact structure, and a dielectric layer. The substrate has first and second device regions, and a fuse region. The first and second transistors are respectively above the first and second device regions. The first fuse is electrically connected to the first transistor and includes a first fuse active region having first and second portions. The second fuse is electrically connected to the second transistor and includes a second fuse active region having third and fourth portions. The contact structure interconnects the second portion and the third portion, wherein the first portion and the fourth portion are on opposite sides of the contact structure. The dielectric layer is between the contact structure and the fuse region of the substrate.

A device includes a memory cell that randomly presents either a first logic state or a second logic state. The memory cell includes: a plurality of first nanostructures extending along a first lateral direction; a plurality of second nanostructures extending along the first lateral direction and disposed at a first side of the plurality of first nanostructures; a plurality of third nanostructures extending along the first lateral direction and disposed at a second side of the plurality of first nanostructures; a dielectric fin structure disposed immediately next to the plurality of first nanostructures along a second lateral direction, wherein a first sidewall of each of the plurality of first nanostructures facing toward or away from the second lateral direction is in contact with the dielectric fin structure; and a first gate structure wrapping around each of the plurality of first nanostructures except for the first sidewall.