CN114256258A - Method for manufacturing NORD flash memory device - Google Patents
Method for manufacturing NORD flash memory device Download PDFInfo
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- CN114256258A CN114256258A CN202111525443.9A CN202111525443A CN114256258A CN 114256258 A CN114256258 A CN 114256258A CN 202111525443 A CN202111525443 A CN 202111525443A CN 114256258 A CN114256258 A CN 114256258A
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- word line
- flash memory
- memory device
- manufacturing
- polysilicon
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B41/00—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates
- H10B41/30—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates characterised by the memory core region
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B41/00—Electrically erasable-and-programmable ROM [EEPROM] devices comprising floating gates
Abstract
The invention discloses a method for manufacturing a flash memory device, which comprises the following steps: step one, carrying out chemical mechanical polishing on word line polycrystalline silicon; step two, carrying out non-blocking etching on the word line; step three, oxidizing the polysilicon; and step four, protecting the silicon nitride deposition. In the invention, after the word line polysilicon is subjected to chemical mechanical polishing, one step of non-blocking etching is added to etch the tunneling oxide layer, and certain loss needs to be caused to the FG SIN below to ensure that the tunneling oxide layer is completely etched, so that the DHF processing time can be greatly reduced before the deposition of the silicon nitride is protected, and the loss of the oxide of the word line polysilicon is correspondingly reduced.
Description
Technical Field
The invention relates to the field of semiconductor manufacturing, in particular to a manufacturing method of a NORD flash memory device.
Background
In the process flow of the NORD Flash memory (Flash) Cell (Cell), the Flash memory Cell is implanted with a large dose after word line (Wordline, WL) Poly (Poly) deposition and Chemical Mechanical Polishing (CMP), and then Poly Oxidation (Poly Oxidation) and Protection silicon nitride (Protection SIN) deposition are performed. Because the CMP of the wordline polysilicon stops on the tunnel Oxide (OX) over the Floating Gate (FG) SIN, a dilute hydrofluoric acid (DHF) rinse is required to remove the tunnel oxide before the protective silicon nitride deposition. The DHF in this step also etches the word line poly-silicon oxide while removing the tunnel oxide layer. In the following control gate connection etching step, the word line polysilicon oxide is not thick enough to protect the word line polysilicon, thereby causing the word line polysilicon pit problem, which becomes an important problem affecting the flash memory yield.
Disclosure of Invention
In view of the above, the present invention provides a method for manufacturing a NORD flash memory device to overcome the drawbacks of the prior art.
The invention solves the technical problems through the following technical scheme: a method of fabricating a NORD flash memory device, comprising the steps of:
step one, carrying out chemical mechanical polishing on word line polycrystalline silicon;
step two, carrying out non-blocking etching on the word line;
step three, oxidizing the polysilicon;
and step four, protecting the silicon nitride deposition.
Preferably, the first step is preceded by word line polysilicon deposition.
Preferably, the barrier-free etching in the second step is dry etching.
Preferably, said step four is preceded by rinsing with dilute hydrofluoric acid.
Preferably, the first step is to planarize the word line polysilicon after chemical mechanical polishing.
Preferably, the protective silicon nitride is a barrier layer.
Preferably, the third step adopts a thermal oxidation growth mode to grow the polycrystalline silicon oxide layer.
Preferably, the step four adopts a chemical vapor deposition method to deposit protective silicon nitride.
The positive progress effects of the invention are as follows: according to the invention, after the word line polysilicon is subjected to chemical mechanical grinding, one step of non-blocking etching is added to etch the tunneling oxide layer, so that before the deposition of Protection silicon nitride (Protection SIN), the DHF processing time can be greatly reduced, the oxide loss of the word line polysilicon is correspondingly reduced, more word line polysilicon oxides are used for protecting the word line polysilicon from being excessively etched in the connection etching of a rear control grid, and the problem of word line pits is solved.
Drawings
FIG. 1 is a flow chart of a method of fabricating a NORD flash memory device of the present invention.
Fig. 2 through 5 are process steps of a method of fabricating a NORD flash memory device according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
As shown in fig. 1 to 5, the method for manufacturing a flash memory device of the present invention includes the steps of:
firstly, carrying out chemical mechanical polishing on word line (Wordline, WL) polycrystalline silicon (Poly), wherein the flash memory device comprises a floating gate silicon nitride layer 11, a tunneling oxide layer 12 and a word line 13;
step two, carrying out non-blocking etching (blanket etch) on the word line;
thirdly, oxidizing the polysilicon to form a word line polysilicon oxide layer 14;
and fourthly, depositing protective silicon nitride (Protection SIN) to form a protective silicon nitride layer 15.
Word line polysilicon deposition is carried out before the first step, so that the subsequent use is facilitated.
And the non-blocking etching in the second step adopts dry etching to etch the tunneling oxide layer, so that the rinsing amount of dilute hydrofluoric acid before the fourth step is reduced.
And rinsing with dilute hydrofluoric acid (DHF) to clean residues before the fourth step, so that the product quality is improved.
In the first step, word line polysilicon is flattened after chemical mechanical polishing, so that the subsequent use is facilitated.
And the protective silicon nitride is used as a barrier layer to protect the flash memory area when the non-flash memory area is etched.
And step three, growing a polycrystalline silicon oxide layer in a thermal oxidation growth mode for protecting the word line in subsequent control gate connection etching.
And step four, depositing and protecting silicon nitride by adopting a chemical vapor deposition method, so that the deposition efficiency and effect are improved.
According to the invention, after the word line polysilicon is subjected to chemical mechanical grinding, one step of non-blocking etching is added to etch the tunneling oxide layer, so that before the deposition of Protection silicon nitride (Protection SIN), the DHF processing time can be greatly reduced, the oxide loss of the word line polysilicon is correspondingly reduced, more word line polysilicon oxides are used for protecting the word line polysilicon from being excessively etched in the connection etching of a rear control grid, and the problem of word line pits is solved.
The above-mentioned embodiments are preferred embodiments of the present invention, and the present invention is not limited thereto, and any other modifications or equivalent substitutions that do not depart from the technical spirit of the present invention are included in the scope of the present invention.
Claims (8)
1. A method of manufacturing a flash memory device, comprising the steps of:
step one, carrying out chemical mechanical polishing on word line polycrystalline silicon;
step two, carrying out non-blocking etching on the word line;
step three, oxidizing the polysilicon;
and step four, protecting the silicon nitride deposition.
2. The method of manufacturing a flash memory device according to claim 1, wherein the first step is preceded by a word line polysilicon deposition.
3. The method for manufacturing a flash memory device according to claim 1, wherein the barrier-free etching in the second step is dry etching.
4. The method of claim 1, wherein the fourth step is preceded by a rinsing with dilute hydrofluoric acid.
5. The method of manufacturing a flash memory device of claim 1, wherein said first step is planarizing the word line polysilicon after chemical mechanical polishing.
6. The method of manufacturing a flash memory device according to claim 1, wherein the protective silicon nitride is a barrier layer.
7. The method of manufacturing a flash memory device according to claim 1, wherein the third step is to grow a polysilicon oxide layer by thermal oxidation growth.
8. The method of claim 1, wherein the step four comprises depositing the protective silicon nitride by chemical vapor deposition.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111525443.9A CN114256258A (en) | 2021-12-14 | 2021-12-14 | Method for manufacturing NORD flash memory device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111525443.9A CN114256258A (en) | 2021-12-14 | 2021-12-14 | Method for manufacturing NORD flash memory device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114256258A true CN114256258A (en) | 2022-03-29 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111525443.9A Pending CN114256258A (en) | 2021-12-14 | 2021-12-14 | Method for manufacturing NORD flash memory device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114256258A (en) |
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2021
- 2021-12-14 CN CN202111525443.9A patent/CN114256258A/en active Pending
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