Patent Application
20190123057
This application is a continuation of International Patent Application No. PCT/CN2017/107594 with a filing date of Oct. 25, 2017, designating the United States, now pending. The content of the aforementioned applications, including any intervening amendments thereto, are incorporated herein by reference.
The present invention relates to the field of memory technology, and in particular to a novel non-volatile memory and a method for manufacturing the same.
A non-volatile memory, also known as the non-volatile memory, is referred to as NVM, which means that the information stored in the memory can still exist for a long time after power is turned off, and is not easily lost. A two-transistor non-volatile memory refers to a memory including two transistors, one is a selection transistor functioning as selection and the other is a memory transistor functioning as storage. At present, the high-performance two-transistor memory has the disadvantages of a complicated process, and a logic-based process thereof requiring an additional dozen or more photomasks, and a high cost.
An object of the present invention is to improve the above-mentioned deficiencies in the prior art and provide a novel non-volatile memory and a method for manufacturing the same.
In order to achieve the above object, the embodiments of the present invention provide the following technical solutions:
A novel non-volatile memory comprises a selection transistor and a memory transistor, the selection transistor comprises a gate oxide layer and a first logic gate. Furthermore, the gate oxide layer is a gate oxide of a first inter-gate dielectric layer or a peripheral logic device.
In the above novel non-volatile memory, the selection transistor is composed of the gate oxide layer and a first logic gate, and the process of forming the first logic gate is more simplified than the process of forming a control gate in the conventional selection transistor, thus making the manufacturing process of the entire memory is simpler, furthermore, the processes of stacking the conventional control gate and a floating gate and removing the inter-gate dielectric layer are omitted, which further simplifies the manufacturing process of the memory and reduces the number of photomasks used, the traditional ten or more photomasks are reduced to four photomasks, which in turn reduces the manufacturing cost of the memory. In addition, by adjusting the thickness of the first inter-gate dielectric layer, or by using the gate oxide of the peripheral logic device as the gate oxide layer, a read rate can still be improved and a data retention capability is excellent.
Furthermore, in the above novel non-volatile memory, the memory transistor comprises a tunneling dielectric layer, the floating gate, a second inter-gate dielectric layer and a second logic gate arranged in sequence. Replacing the conventional control gate with the second logic gate can further simplify the manufacturing process of the entire memory and reduce manufacturing complexity.
Furthermore, in the above novel non-volatile memory, the second inter-gate dielectric layer extends from the top surface of the floating gate toward the sidewall thereof, surrounds the floating gate, and takes the tunneling electrical layer as the bottom, the floating gate is wrapped up by the second inter-gate dielectric layer and the tunneling dielectric layer; and the second logic gate surrounds part or all of the second inter-gate dielectric layer.
Compared with a conventional stacked type structure, the present invention increases the contact area between the second logic gate and the second inter-gate dielectric layer by an enclosing manner, that is, increases the capacitance of the second logic gate to the floating gate, thereby increasing the coupling ratio of the second logic gate to the floating gate.
The embodiments of the present invention further provide a novel non-volatile memory of another structure, comprising the memory transistor, the memory transistor comprises the tunneling dielectric layer, the floating gate, the second inter-gate dielectric layer, and the second logic gate arranged in sequence. By replacing the conventional control gate with the second logic gate, the manufacturing process flow of the memory can be simplified.
Furthermore, in the above novel non-volatile memory, the second inter-gate dielectric layer extends from the top surface of the floating gate toward the sidewall thereof, surrounds the floating gate, and takes the tunneling electrical layer as the bottom, the floating gate is wrapped up by the second inter-gate dielectric layer and the tunneling dielectric layer; and the second logic gate surrounds part or all of the second inter-gate dielectric layer.
Furthermore, the second logic gate surrounds a top surface and two sidewalls of the second inter-gate dielectric layer.
The embodiments of the present invention provides a method for manufacturing a novel non-volatile memory at the same time, the method comprising the steps of:
forming the tunneling dielectric layer in a memory transistor structure on a substrate after an isolation process of a shallow trench;
depositing a floating gate material;
forming a floating gate in the memory transistor structure via an etching process by means of a photomask;
forming a first inter-gate dielectric layer in the selection transistor and the second inter-gate dielectric layer in the memory transistor structure via a thermal oxidation method or a thin film deposition method; and
forming a first logic gate in the selection transistor and a second logic gate in the memory transistor structure via the etching process by means of the photomask.
The memory is manufactured by the above method, the process is simple, the traditional memory manufacturing process flow is simplified, the use of the photomask is reduced, and the cost is saved. In addition, by a manner of forming the floating gate via the etching process by means of the photomask, the thickness of the floating gate can be made larger, and the memory performance of the memory is better.
In another embodiment, the step of forming the floating gate in the memory transistor structure via the etching process by means of the photomask is replaced by the following steps: using the height difference between a shallow trench isolation STI and an active region, and using the photomask to form the floating gate in the memory transistor structure via the etching process again after a chemical mechanical polishing process. Using this method to form the floating gate can avoid some of the limitations of the process rules, so that the memory cell can be made smaller.
In a further optimized solution, in the above method, in the step of forming the second inter-gate dielectric layer via the thermal oxidation method or the thin film deposition method, the second inter-gate dielectric layer extends from the top surface of the floating gate toward the sidewall thereof, surrounds the floating gate and takes the tunneling electrical layer as the bottom, the floating gate is wrapped up by the second inter-gate dielectric layer and the tunnel dielectric layer; in the step of forming the second logic gate via the etching process by means of the photomask, the second logic gate surrounds part or all of the second inter-gate dielectric layer.
Compared with the prior art, the novel non-volatile memory of the present invention and the method for manufacturing the same have the beneficial effects:
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings to be used in the embodiments will be briefly described below, it should be understood that the following drawings show only certain embodiments of the present invention, and therefore, it should be seen as a limitation on the scope, and the person skilled in the art can obtain other related drawings according to the drawings without any creative work.
Substrate 10; selection transistor 20; memory transistor 30; shallow trench isolation STI 40; P-type doped region 101; N-type well 102; gate oxide layer 201; first logic gate 202; tunneling dielectric layer 301; floating gate 302; second inter-gate dielectric layer 303; second logic gate 304.
The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention, it is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all embodiments, the components of the embodiments of the invention, which are generally described and illustrated in the figures herein, may be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention in the figures is not designed to limit the scope of the present invention required to be protected, but merely shows the selected embodiments of the present invention. All other embodiments obtained by the person skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.
It should be noted that in the description of the present invention, the terms “first”, “second”, etc. are used only to distinguish the description, and are not to be construed as indicating or implying relative importance.
Referring to
In the above novel non-volatile memory, the control gates of the selection transistor 20 and the memory transistor 30 are replaced by the logic gate, and the process of forming the logic gate is more simplified than the process of forming the control gate, thus making the entire memory manufacturing process simpler. In addition, compared with the structure of the conventional selection transistor 20, that is, the control gate of the selection transistor 20 and the floating gate 302 are stacked together, and the inter-gate dielectric layer is removed, the manufacturing process of the selection transistor 20 in the present invention is omitted, in the present invention, from the process of manufacturing the selection transistor 20, the processes of stacking the control gate and the floating gate 302 and removing the inter-gate dielectric layer not only further simplify the manufacturing process of the selection transistor 20, but also reduce the number of the photomasks used, the conventional ten or more photomasks are reduced to four photomasks, which in turn reduces the manufacturing cost of the memory and simplifies the structure of the selection transistor 20. In addition, by adjusting the thickness of the first inter-gate dielectric layer, or by using the gate oxide of the peripheral logic device as the gate oxide layer 201, the read rate can be improved and the data retention capability is excellent.
In a further optimized solution, for the memory transistor 30, the second inter-gate dielectric layer 303 extends from the top surface of the floating gate 302 toward the sidewall thereof, surrounds the floating gate 302, and takes the tunneling dielectric layer 301 as the bottom, the floating gate 302 is wrapped up by the second inter-gate dielectric layer 303 and the tunneling dielectric layer 301; the second logic gate 304 surrounds part or all of the second inter-gate dielectric layer 303. For example,
Compared with the conventional two-transistor type non-volatile memory, in the above-described first embodiment, the structures of the selection transistor 20 and the memory transistor 30 are both improved, but it is easy to understand that, in a feasible solution, only the structure of the selection transistor 20 can be improved, that is, the selection transistor 20 comprises the gate oxide layer 201 and the first logic gate 202, or only the structure of the memory transistor 30 can be improved, that is, the conventional control gate is replaced with the second logic gate 304. Both of these feasible solutions can solve the problem of poor compatibility of traditional non-volatile memory and the logic device. In addition, the improvement of the structure of the memory transistor 30 can also be applied to a single-transistor floating volatile memory, that is, the single-transistor floating volatile memory comprises the memory transistor 30, the memory transistor 30 comprises the tunneling dielectric layer 301, the floating gate 302, the second inter-gate dielectric layer 303, and the second logic gate 304 arranged in sequence.
As shown in
Referring to
S101, forming the tunneling dielectric layer in the structure of the memory transistor 30 on the substrate 10, after the isolation process of the shallow trench.
S102, depositing the material of the floating gate 302.
S103, forming the floating gate 302 in the structure of the memory transistor 30 via the etching process by means of the photomask; or using the height difference between a shallow trench isolation STI and an active region, and then forming the floating gate 302 in the structure of the memory transistor 30 via the etching process by means of the photomask after the chemical mechanical polishing process. The thickness of the floating gate 302 can be made thick by the method for forming the floating gate 302 via the etching process by means of the photomask, thereby increasing the storage capacity; however, a method for grinding and etching can avoid the limitation of a plurality of process rules, a storage unit can be made smaller to adapt to the trend of product miniaturization.
S104, forming a first inter-gate dielectric layer in the selection transistor 20 and a second inter-gate dielectric layer 303 in the structure of the memory transistor 30 via a thermal oxidation method or a thin film deposition method. In this step, in order to enhance the coupling performance of the memory, during the process of forming the second inter-gate dielectric layer 303, the second inter-gate dielectric layer 303 can extend from the top surface of the floating gate 302 toward the sidewall thereof, surrounds the floating gate 302 and takes the tunneling dielectric layer 301 as the bottom, the floating gate 302 is wrapped up by the second inter-gate dielectric layer 303 and the tunnel dielectric layer 301.
S105, forming a first logic gate 202 in the selection transistor 20 and a second logic gate 304 in the structure of the memory transistor 30 via the etching process by means of the photomask. In this step, in order to enhance the coupling performance of the memory, during the process of forming the second logic gate 304, the second logic gate 304 can surround part or all of the second inter-gate dielectric layer 303.
The above is only the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention, which should be covered by the scope of the present invention.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2017/107594 | Oct 2017 | US |
| Child | 16199201 | US |
