CN113517345A - Method for manufacturing transistor, basic memory cell, and dynamic random access memory - Google Patents

Abstract

The present invention provides a method for manufacturing a transistor, a transistor, a basic memory unit, and a dynamic random access memory. The method includes the following steps: forming a conductive channel, the conductive channel includes a columnar body and ends on both sides, at least one of the ends is protruding; forming a gate insulating layer surrounding the columnar body and exposing the ends on both sides of the conductive channel; a gate electrode surrounding the gate insulating layer is formed; and a source electrode and a drain electrode are formed on the ends on both sides of the conductive channel. The above transistors are improved from the horizontal direction transistors in the prior art to the vertical direction, so that the area occupied by a single transistor in the horizontal direction is reduced, the number of transistors per unit area is increased, and the transistor density is improved.

Description

Method for manufacturing transistor, basic memory cell, and dynamic random access memory

Technical Field

The present invention relates to the field of semiconductor processes, and more particularly, to a method for manufacturing a transistor, a basic memory cell, and a dynamic random access memory.

Background

The basic unit of the dynamic random access memory is shown in FIG. 1A, and the memory is formed by the array structure shown in FIG. 1B. The basic unit is commonly referred to as the 1T1C structure. The 1T, i.e., the transistor, mainly has two structures, i.e., a planar transistor shown in fig. 2A and a buried channel array transistor shown in fig. 2B. In the transistors with the two structures, the source electrode and the drain electrode are distributed on two sides of the grid electrode in the horizontal plane direction, so that the area occupied by the transistors in the horizontal direction is larger.

Because the bit line and the storage device of the dynamic random access memory are respectively connected with one of the source electrode and the drain electrode, the transistors with the two structures are used for manufacturing the memory, the capacitors of the bit line and the storage device are both positioned on the same side of the grid electrode and are both positioned on the same surface of the wafer in the processing technology, so that the whole technology has higher complexity, especially has extremely high requirements on photoetching and related technologies, the control difficulty of the technological process is higher, and the failure rate is higher.

Therefore, how to make up for the shortcomings of the prior art and achieve breakthrough in transistor density and process manufacturing difficulty is a problem that needs to be solved in the prior art.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a method for manufacturing a transistor, a basic memory cell, and a dynamic random access memory, which can improve the density of the transistor and reduce the process manufacturing difficulty.

In order to solve the above problems, the present invention provides a method for manufacturing a transistor, comprising the steps of: forming a conductive channel, wherein the conductive channel comprises a columnar body and end parts on two sides, and at least one end part is arranged in a protruding mode; forming a gate insulating layer surrounding the columnar body and exposing end parts on two sides of the conductive channel; forming a gate electrode surrounding the gate insulating layer; and forming a source electrode and a drain electrode at both side ends of the conductive channel.

In order to solve the above problem, the present invention provides a transistor including: the conductive channel comprises a columnar body and end parts on two sides, wherein at least one end part is arranged in a protruding mode; a gate insulating layer surrounding the columnar body; a gate electrode surrounding the gate insulating layer; and a source electrode and a drain electrode covering both side end portions of the conductive channel.

In order to solve the above problem, the present invention provides a basic memory cell of a dynamic random access memory, including a transistor and a capacitor, the transistor including: the conductive channel comprises a columnar body and end parts on two sides, wherein at least one end part is arranged in a protruding mode; a gate insulating layer surrounding the columnar body; a gate electrode surrounding the gate insulating layer; and a source electrode and a drain electrode covering both side end portions of the conductive channel.

In order to solve the above problem, the present invention provides a dynamic random access memory, comprising a plurality of basic memory cells, wherein each basic memory cell comprises a transistor and a capacitor, and the transistor comprises: the conductive channel comprises a columnar body and end parts on two sides, wherein at least one end part is arranged in a protruding mode; a gate insulating layer surrounding the columnar body; a gate electrode surrounding the gate insulating layer; and a source electrode and a drain electrode covering both side end portions of the conductive channel.

The transistor is improved from a horizontal transistor in the prior art to a vertical transistor, so that the area occupied by a single transistor in the horizontal direction is reduced, the number of transistors in a unit area is increased, and the transistor density is improved; the transistor channel and the gate surround the whole transistor along the horizontal direction, so that the control capability of the gate is increased, and the performance of the transistor is improved; the source electrode and the drain electrode at two ends of the transistor are respectively processed and generated on two surfaces of a single wafer and are not directly connected with the substrate, and the transistor can be attached to another wafer through a bonding process subsequently, so that the structure is flexible, and the transistor is easy to process and manufacture.

Drawings

FIG. 1A is a prior art DRAM cell.

FIG. 1B is a prior art DRAM array structure.

Fig. 2A and 2B are schematic diagrams illustrating a planar transistor structure in a dynamic random access memory according to the prior art.

Fig. 3 is a schematic diagram illustrating steps of a method for manufacturing a transistor according to an embodiment of the present invention.

Fig. 4A to 4D are process diagrams illustrating a method for manufacturing a transistor according to an embodiment of the invention.

Detailed Description

The following detailed description of the embodiments of the transistor fabrication method, the transistor, the basic memory cell, and the dynamic random access memory according to the present invention will be made with reference to the accompanying drawings.

FIG. 3 is a schematic diagram of the implementation steps of a specific embodiment of the transistor manufacturing method of the present invention, including: step S30, forming a conductive channel, wherein the conductive channel comprises a columnar body and end parts on two sides, and at least one end part is arranged in a protruding manner; step S31, forming a gate insulating layer surrounding the pillar-shaped body and exposing end portions of both sides of the conductive channel; step S32, forming a gate electrode surrounding the gate insulating layer; step S33, forming a source electrode and a drain electrode at both side ends of the conductive channel.

Fig. 4A to 4D are schematic process diagrams illustrating the above steps.

Referring to step S30, shown in fig. 4A, a conductive channel 40 is formed, the conductive channel 40 including a columnar body 401 and upper and lower ends 402, 403. In the present embodiment, the lower end 403 is protruded. In other embodiments, the upper end 402 or both ends may be protruded. In this embodiment, the pillar-shaped conductive channel 40 is formed in a silicon substrate (not shown), which is preferably a doped monocrystalline silicon material, such as N-type or P-type monocrystalline silicon. In other embodiments, the formation of a conductive channel within a substrate of any one of the common semiconductor materials may also be employed. In the present embodiment, the columnar structure of the conductive channel 40 is a prism, in particular, a quadrangular prism structure. In other embodiments, cylinders, triangular prisms, pentagonal prisms, and any shape of cylinder should be considered as possible.

Referring to step S31, as shown in fig. 4B, a gate insulating layer 41 surrounding the pillar-shaped body 401 is formed and both ends of the conductive channel 40 are exposed. The material of the gate insulating layer 41 is preferably selected from any one of silicon oxide, silicon nitride, and silicon oxynitride, and any common insulating material including, but not limited to, oxide should be considered as an optional material for forming the gate insulating layer 41.

As shown in fig. 4C, referring to step S32, a gate electrode 42 surrounding the gate insulating layer 41 is formed. The material of the gate electrode 42 may be any metal conductive material or polysilicon material, including but not limited to aluminum, copper, and other metals used for the interconnect structure of the integrated circuit, and the forming method may be sputtering, physical deposition, evaporation, and the like.

As shown in fig. 4D, referring to step S33, the source electrode 43 and the drain electrode 44 are formed at the upper end portion 402 and the lower end portion 403 of both sides of the conductive channel 40. The material of the source electrode 43 and the drain electrode 44 can be any metal conductive material, including but not limited to aluminum, copper, and other metals used for the interconnect structure of the integrated circuit, and the forming method can be sputtering, physical deposition, evaporation, and the like. In this embodiment, the source electrode 43 is disposed above the substrate, and the drain electrode 44 is disposed below the substrate. In this step, the source electrode 43 is formed on the front surface of the silicon substrate, and the drain electrode 44 on the back surface may be formed by first thinning the silicon substrate to a predetermined thickness and then fabricating the drain electrode 44.

The transistor formed after the above process is implemented is a transistor with a vertical structure, and includes: a conductive channel 40, wherein the conductive channel 40 comprises a columnar body 401, an upper end 402 and a lower end 403, and in the present embodiment, the lower end 403 is protruded; a gate insulating layer 41 surrounding the columnar body 401; a gate electrode 42 surrounding the gate insulating layer 41; and a source electrode 43 and a drain electrode 44 covering both upper and lower end portions 402 and 403 of the conductive channel 40.

The transistor is improved from a horizontal transistor in the prior art to a vertical transistor, so that the area occupied by a single transistor in the horizontal direction is reduced, the number of transistors in a unit area is increased, and the transistor density is improved; the lower end part and the corresponding leakage electrode are arranged in a protruding mode, and can be further directly interconnected with adjacent transistors through transverse or longitudinal extension to form a memory array, so that a metal interconnection structure is prevented from being manufactured again, and process steps are saved; the transistor channel and the gate surround the whole transistor along the horizontal direction, so that the control capability of the gate is increased, and the performance of the transistor is improved; the source electrode and the drain electrode at two ends of the transistor are respectively processed and generated on two surfaces of a single wafer and are not directly connected with the substrate, and the transistor can be attached to another wafer through a bonding process subsequently, so that the structure is flexible, and the transistor is easy to process and manufacture.

The above structure can be used to construct the basic memory cell of a dynamic random access memory. The basic memory cell comprises a transistor and a capacitor, the so-called 1T1C configuration. The transistor includes: a conductive channel 40, wherein the conductive channel 40 comprises a columnar body 401, an upper end 402 and a lower end 403, and in the present embodiment, the lower end 403 is protruded; a gate insulating layer 41 surrounding the columnar body 401; a gate electrode 42 surrounding the gate insulating layer 41; and a source electrode 43 and a drain electrode 44 covering both upper and lower end portions 402 and 403 of the conductive channel 40.

The above structure can be further used to form a dynamic random access memory, which includes a plurality of basic memory cells including a transistor and a capacitor, so-called 1T1C structure. The transistor includes: a conductive channel 40, wherein the conductive channel 40 comprises a columnar body 401, an upper end 402 and a lower end 403, and in the present embodiment, the lower end 403 is protruded; a gate insulating layer 41 surrounding the columnar body 401; a gate electrode 42 surrounding the gate insulating layer 41; and a source electrode 43 and a drain electrode 44 covering both upper and lower end portions 402 and 403 of the conductive channel 40.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (11)

1. a manufacturing method of transistor, is characterized in that, comprises the steps: forming a conductive channel, the conductive channel includes a columnar body and ends on both sides, at least one of the ends is protruding; forming a gate insulating layer surrounding the columnar body and exposing ends of both sides of the conductive channel; forming a gate electrode surrounding the gate insulating layer; A source electrode and a drain electrode are formed at the ends on both sides of the conductive channel. 2. The method according to claim 1, wherein the columnar structure of the columnar body is selected from any one of cylinders and prisms. 3 . The method of claim 1 , wherein the gate insulating layer is made of a material selected from any one of silicon oxide, silicon nitride, and silicon oxynitride. 4 . 4 . The method according to claim 1 , wherein the gate electrode, the source electrode, and the drain electrode are all made of metal materials. 5 . 5. A transistor, characterized in that, comprising: a conductive channel, the conductive channel includes a columnar body and ends on both sides, at least one of the ends is protruding; a gate insulating layer surrounding the columnar body; a gate electrode surrounding the gate insulating layer; and The source electrode and the drain electrode at both ends of the conductive channel are covered. 6 . The transistor according to claim 5 , wherein the columnar structure of the columnar body is selected from any one of cylinders and prisms. 7 . 7 . The transistor according to claim 5 , wherein the gate insulating layer is made of a material selected from any one of silicon oxide, silicon nitride, and silicon oxynitride. 8 . 8 . The transistor of claim 5 , wherein the gate electrode, the source electrode, and the drain electrode are all made of metal materials. 9 . 9. A basic storage unit of a dynamic random access memory, comprising a transistor and a capacitor, wherein the transistor comprises: a conductive channel, the conductive channel includes a columnar body and ends on both sides, at least one of the ends is protruding; a gate insulating layer surrounding the columnar body; a gate electrode surrounding the gate insulating layer; and The source electrode and the drain electrode at both ends of the conductive channel are covered. 10. A dynamic random access memory, comprising an array of a plurality of basic memory cells, the basic memory cells comprising a transistor and a capacitor, wherein the transistor comprises: a conductive channel, the conductive channel includes a columnar body and ends on both sides, at least one of the ends is protruding; a gate insulating layer surrounding the columnar body; a gate electrode surrounding the gate insulating layer; and The source electrode and the drain electrode at both ends of the conductive channel are covered. 11 . The dynamic random access memory according to claim 10 , wherein the array of basic memory cells includes two adjacent transistors, and the ends of the two adjacent transistors protruding from each other are connected to each other. 12 .

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