CN114143687B - Piezoelectric microphone of micro-electromechanical system, manufacturing method thereof and electronic equipment - Google Patents
Piezoelectric microphone of micro-electromechanical system, manufacturing method thereof and electronic equipment Download PDFInfo
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- CN114143687B CN114143687B CN202111314139.XA CN202111314139A CN114143687B CN 114143687 B CN114143687 B CN 114143687B CN 202111314139 A CN202111314139 A CN 202111314139A CN 114143687 B CN114143687 B CN 114143687B
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 18
- 239000000758 substrate Substances 0.000 claims abstract description 57
- 230000001678 irradiating effect Effects 0.000 claims abstract description 12
- 238000005530 etching Methods 0.000 claims description 10
- 239000010409 thin film Substances 0.000 claims description 10
- 229910052594 sapphire Inorganic materials 0.000 claims description 8
- 239000010980 sapphire Substances 0.000 claims description 8
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 7
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 6
- 238000009616 inductively coupled plasma Methods 0.000 claims description 4
- 238000000227 grinding Methods 0.000 claims description 2
- 238000005498 polishing Methods 0.000 claims 1
- 239000010408 film Substances 0.000 description 9
- 239000013078 crystal Substances 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000001451 molecular beam epitaxy Methods 0.000 description 4
- 238000001020 plasma etching Methods 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical group [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000000608 laser ablation Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 210000002159 anterior chamber Anatomy 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000014509 gene expression Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 238000005240 physical vapour deposition Methods 0.000 description 1
- 238000007517 polishing process Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000000927 vapour-phase epitaxy Methods 0.000 description 1
- 238000001039 wet etching Methods 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R17/00—Piezoelectric transducers; Electrostrictive transducers
- H04R17/02—Microphones
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Manufacturing & Machinery (AREA)
- Piezo-Electric Transducers For Audible Bands (AREA)
- Micromachines (AREA)
Abstract
A piezoelectric microphone of a micro-electro-mechanical system, a method of manufacturing the piezoelectric microphone, and an electronic apparatus are disclosed. The manufacturing method comprises the following steps: forming a piezoelectric microphone device layer on a device substrate, wherein the device substrate is laser transparent; processing the device substrate to form a back hole; and releasing the piezoelectric microphone device layer from the device substrate by laser lift-off by irradiating laser from the device substrate side, wherein a window irradiating laser defines a boundary releasing the piezoelectric microphone device layer.
Description
Technical Field
The present disclosure relates to the field of mems piezoelectric microphone manufacturing technologies, and more particularly, to a mems piezoelectric microphone manufacturing method, a piezoelectric microphone, and an electronic device.
Background
Mems piezoelectric microphones are mems microphones that utilize the piezoelectric effect. The piezoelectric material may be, for example, zinc oxide, aluminum nitride, or the like. For example, a polycrystalline aluminum nitride film may be deposited by physical vapor deposition to form a mems piezoelectric microphone.
Currently, mems piezoelectric microphones are highly reliable, e.g., they have a high acoustic overload point AOP/dynamic range, low power consumption, and can be dust-proof, water-proof, etc.
But the performance of a mems piezoelectric microphone is low, e.g., its signal to noise ratio is low.
Disclosure of Invention
It is an object of the present disclosure to provide a new solution for a microelectromechanical system piezoelectric microphone.
According to a first aspect of the present disclosure, there is provided a method of manufacturing a mems piezoelectric microphone, wherein the method of manufacturing includes: forming a piezoelectric microphone device layer on a device substrate, wherein the device substrate is laser transparent; processing the device substrate to form a back hole; and releasing the piezoelectric microphone device layer from the device substrate by laser lift-off by irradiating laser from the device substrate side, wherein a window irradiating laser defines a boundary releasing the piezoelectric microphone device layer.
According to a second aspect of the present disclosure, there is provided a mems piezoelectric microphone manufactured using the manufacturing method provided by the present disclosure.
According to a third aspect of the present disclosure, there is provided an electronic device comprising the mems piezoelectric microphone provided by the present disclosure.
According to one embodiment of the disclosure, the release boundary of the mems piezoelectric microphone can be defined more precisely by irradiating laser light from the bottom side of the device substrate, and irradiating a window of the laser light to define the boundary of the device layer.
Other features of the present disclosure and its advantages will become apparent from the following detailed description of exemplary embodiments of the disclosure, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure.
FIG. 1 shows a schematic diagram of an undefined portion of a back hole sidewall of a MEMS piezoelectric microphone.
Fig. 2-6 illustrate a schematic flow of fabricating a mems piezoelectric microphone according to one embodiment.
Fig. 7 shows a schematic diagram of an electronic device according to an embodiment.
Reference numerals illustrate:
1. A device substrate; 2. a piezoelectric microphone device layer; 3. bonding pads and interconnection structures; 4. an electrode layer; 5. a back hole; 51. an undefined portion of the back hole sidewall; 6. a via or trench; 11. a device substrate; 12. a piezoelectric microphone device layer; 13. bonding pads and interconnection structures; 14. an electrode layer; 141. a bottom electrode layer; 1411. a thinned bottom electrode layer; 1412. an unrefined bottom electrode layer; 15. a back hole; 151. an undefined portion of the back hole sidewall; 16. a laser window; 17. a laser boundary; 18. a via or trench; 200. an electronic device; 201. microelectromechanical system piezoelectric microphones.
Detailed Description
Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless it is specifically stated otherwise.
The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses.
Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.
In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of exemplary embodiments may have different values.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.
Because of the smaller size of mems devices, it is more difficult to achieve microphone products with higher signal-to-noise ratios.
The inventors have found in research that, in general, in a piezoelectric microphone, a plurality of aluminum nitride films (each layer is less than 1 μm) are laminated together, for example, two aluminum nitride films are sandwiched between three electrode layers.
Currently, piezoelectric thin films, such as AlScN, alN, etc., may be formed by epitaxial growth (molecular beam epitaxy MBE, metal organic chemical vapor deposition MOCVD, etc.) on sapphire or silicon carbide substrates. The thickness of the piezoelectric film may be 0.3 to 0.6 micrometers.
Fig. 1 shows a schematic diagram of a mems piezoelectric microphone. As shown in fig. 1, a piezoelectric microphone device layer 2 is formed on a device substrate 1. The piezoelectric microphone device layer 2 includes a piezoelectric thin film layer sandwiched between a plurality of electrode layers 4. A pad and interconnect structure 3 are also formed in the piezoelectric microphone device layer 2. The piezoelectric microphone device layer 2 may also be formed with vias or trenches 6.
The inventors have found that, when releasing the piezoelectric microphone device layer 2, there is uncertainty in the piezoelectric microphone device layer 2 when forming a back hole to release the piezoelectric microphone device layer 2 due to process limitations, thereby affecting the performance of the piezoelectric microphone, as shown in fig. 1. As shown in fig. 1, for example, the device substrate 1 is a sapphire substrate. The device substrate 1 is etched, for example, by reactive coupled plasma ICP or reactive ion etching RIE, to form a back hole 5. In general, the sidewall profile of the back hole 5 cannot be perfectly defined, for example, there may be a phenomenon of incomplete etching or etching angle at the sidewall. Thus, as shown in fig. 1, an undefined portion 51 is generated at the side wall of the back hole 5. The uncertainty 51 causes the boundaries of the piezoelectric microphone device layer 2 to change, thereby affecting the performance/yield of the piezoelectric microphone.
Here, the inventors propose to accurately define the boundary of the piezoelectric microphone device layer 2 by means of laser lift-off, thereby improving uniformity of performance of the piezoelectric microphone.
Fig. 2-6 illustrate a schematic flow of fabricating a mems piezoelectric microphone according to one embodiment.
As shown in fig. 2, a piezoelectric microphone device layer 12 is formed on a device substrate 11.
The device substrate 11 is laser transparent, for example, it may be a sapphire or silicon carbide substrate. The sapphire or silicon carbide substrate has higher rigidity relative to the silicon substrate, for example, the young's modulus of the sapphire or silicon carbide substrate of single crystal is 2 to 4 times that of the silicon substrate. Thus, a thinner device substrate can be realized. For example, the thickness of the silicon substrate is greater than 200 microns, while the single crystal sapphire or silicon carbide substrate may be 50 to 200 microns, preferably 100 to 150 microns. Moreover, single crystal sapphire or silicon carbide substrates may have lower package stress effects. This can significantly reduce the anterior chamber size, thereby improving high frequency performance, as well as increasing signal-to-noise ratio and high frequency response peaks, etc.
Here, "laser transparent" means that the device substrate 11 is transparent to laser light for laser lift-off.
The piezoelectric microphone device layer 12 comprises a piezoelectric microphone device layer comprising at least two electrode layers 14 and at least one piezoelectric thin film layer. As an example, in fig. 2, two piezoelectric film layers are sandwiched between three electrode layers 14. The material of the piezoelectric thin film layer is, for example, a single crystal piezoelectric material, for example, alScN, alN, or the like. For example, the thickness of the piezoelectric thin film layer ranges from 0.3 to 0.6 micrometers. The electrode layer 14 is, for example, a metal electrode layer.
The device substrate 11 on which the piezoelectric thin film layer is grown may be a growth substrate having a diameter of 8 inches. The piezoelectric thin film (single crystal AlN, alScN, or polycrystalline thin film, etc.) and the metal electrode layer may be grown on the device substrate 11 by molecular beam epitaxy MBE or metal organic chemical vapor deposition MOCVD/metal organic vapor phase epitaxy growth MOVPE. This can result in very thin high quality films due to the large lattice matching.
Pads and interconnect structures 13, vias or trenches 18, passivation layers (not shown), etc. may also be formed on the piezoelectric microphone device layer 12.
As shown in fig. 3, the device substrate 11 is processed to form a back hole 15.
For example, the device substrate 11 may be thinned by a back grinding process and/or a polishing process.
Next, a back hole 15 is formed on the device substrate by etching. The device substrate 11 is patterned and etched, for example by inductively coupled plasma etching ICP or reactive ion etching RIE, to form the back holes 15. The portion of the piezoelectric microphone device layer 12 adjacent to the device substrate 11 is the bottom electrode layer 141. The bottom electrode layer 141 is an electrode layer located at the bottom of the electrode layer 14 and adjacent to the device substrate 11. The etching process is stopped at the bottom electrode layer 141.
As shown in fig. 3, an undefined portion 151 is formed in the sidewall of the back hole 15 at the time of processing.
As shown in fig. 4, by irradiating laser light from the device substrate 11 side, the piezoelectric microphone device layer 12 is released from the device substrate 11 by peeling LLO with the laser light. The lasing window 16 defines a boundary 17 that releases the piezoelectric microphone device layer 12. By irradiating laser light, a part of the thickness of the bottom electrode layer 14 can be burned out, for example, 5 to 100 nm.
Fig. 5 shows a partial enlargement of the release boundary. As shown in fig. 5, the bottom electrode layer 1411 irradiated by the laser window 16 is thinned, and the bottom electrode layer 1412 not irradiated by the laser is not thinned and still connects the device substrate 11 and the piezoelectric microphone device layer 12. The boundary of the laser window 16 defines the boundary 17 of the thinned bottom electrode layer, i.e., the boundary of the released piezoelectric microphone device layer 12.
Since the laser window 16 defines the boundary 17 of the released piezoelectric microphone device layer 12, i.e., the uncertainty 151 is contained within the laser window 16, the boundary 17 of the piezoelectric microphone device layer 12 can be more precisely controlled, thereby forming a piezoelectric microphone of consistent performance.
After laser lift-off, wet etching may also be used to clean the bottom electrode layer 1411 and boundaries.
Fig. 6 shows a mems piezoelectric microphone formed by the above steps. Unlike other mems piezoelectric microphones, in the mems piezoelectric microphone shown in fig. 6, laser lift-off is combined with backside body processing/etching. The release boundaries of the mems device layers can be more precisely defined by laser lift-off, for example, on the order of 1 micron. In addition, the boundaries of the MEMS device layers are determined by laser ablation.
Furthermore, since the window for irradiating the laser defines the boundary for releasing the piezoelectric microphone device layer, the boundary for laser ablation is larger than the boundary of the back hole formed by the back side body processing/etching. In this case, a small gap is formed between the device substrate and the piezoelectric microphone device layer along the periphery of the released piezoelectric microphone device layer. On the one hand, the piezoelectric microphone device layer may be mechanically moved in this small gap, thereby picking up sound. On the other hand, the small gap can also play a role in protecting the piezoelectric microphone device layer to a certain extent, and damage caused by excessive displacement is prevented.
The MEMS piezoelectric microphone manufactured in this way can use thinner piezoelectric film, thereby having higher quality. For example, the piezoelectric film has a piezoelectric coefficient |d13| > 3pm/v, and a dielectric loss angle tangent tan delta < 0.002, preferably tan delta < 0.001. The thickness of each piezoelectric film layer may be 0.1 to 2 microns, preferably 0.2 to 1 micron, more preferably 0.3 to 0.6 micron. This can reduce the detection area, realizing a smaller chip or device.
Fig. 7 shows a schematic diagram of an electronic device according to one embodiment disclosed herein. As shown in fig. 7, the electronic device 200 may include a microelectromechanical system piezoelectric microphone 201 shown in fig. 6. The electronic device 200 may be a cell phone, tablet, wearable device, etc.
Although embodiments of the present disclosure have been shown and described. Those of ordinary skill in the art will appreciate that: many variations, modifications, substitutions, and alterations are possible to these embodiments without departing from the principles and spirit of the disclosure. The scope of the disclosure is defined by the claims and their equivalents.
Claims (10)
1. A method of fabricating a microelectromechanical system piezoelectric microphone, comprising:
Forming a piezoelectric microphone device layer on a device substrate, wherein the device substrate is laser transparent;
Processing the device substrate to form a back hole; and
Releasing the piezoelectric microphone device layer from the device substrate by laser lift-off by irradiating laser light from the device substrate side, wherein a window irradiating the laser light defines a boundary releasing the piezoelectric microphone device layer such that the laser ablated boundary is larger than the back hole boundary, thereby forming a small gap between the device substrate and the piezoelectric microphone device layer along the perimeter of the released piezoelectric microphone device layer.
2. The manufacturing method according to claim 1, wherein the device substrate is a sapphire device substrate or a silicon carbide device substrate.
3. The method of manufacturing of claim 1, wherein processing the device substrate to form a back hole comprises:
thinning the device substrate through back grinding treatment and/or polishing treatment; and
A back hole is formed in the device substrate by etching.
4. A method of manufacturing according to claim 3, wherein the etching comprises inductively coupled plasma etching.
5. The method of manufacturing of claim 1, wherein the piezoelectric microphone device layer comprises at least two electrode layers and at least one piezoelectric thin film layer, and the electrode layers comprise a bottom electrode layer located at the bottom and adjacent to the device substrate.
6. The manufacturing method according to claim 5, wherein the thickness of the piezoelectric thin film layer is in the range of 0.3 to 0.6 μm.
7. The method of manufacturing of claim 5, wherein releasing the piezoelectric microphone device layer from the device substrate with laser lift-off comprises:
by irradiating laser light, a part of the thickness of the bottom electrode layer is burned out.
8. The manufacturing method according to claim 7, further comprising:
After laser lift-off, the bottom electrode layer and the boundary are cleaned using a wet etch.
9. A mems piezoelectric microphone fabricated using the fabrication method of claim 1.
10. An electronic device comprising a microelectromechanical system piezoelectric microphone according to claim 9.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111314139.XA CN114143687B (en) | 2021-11-08 | 2021-11-08 | Piezoelectric microphone of micro-electromechanical system, manufacturing method thereof and electronic equipment |
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| CN202111314139.XA CN114143687B (en) | 2021-11-08 | 2021-11-08 | Piezoelectric microphone of micro-electromechanical system, manufacturing method thereof and electronic equipment |
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| CN114143687A CN114143687A (en) | 2022-03-04 |
| CN114143687B true CN114143687B (en) | 2024-07-30 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111800716A (en) * | 2020-07-03 | 2020-10-20 | 安徽奥飞声学科技有限公司 | A kind of MEMS structure and its forming method |
| CN113264500A (en) * | 2021-04-27 | 2021-08-17 | 歌尔微电子股份有限公司 | Micro-electromechanical device, manufacturing method thereof and electronic equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP5348073B2 (en) * | 2010-06-01 | 2013-11-20 | 船井電機株式会社 | Electroacoustic transducer mounting substrate, microphone unit, and manufacturing method thereof |
| TW201943069A (en) * | 2013-09-06 | 2019-11-01 | 日商半導體能源研究所股份有限公司 | Light emitting device and manufacturing method of light emitting device |
| US9309105B2 (en) * | 2014-03-06 | 2016-04-12 | Infineon Technologies Ag | Sensor structure for sensing pressure waves and ambient pressure |
| CN105635865B (en) * | 2014-10-30 | 2019-04-05 | 中芯国际集成电路制造(上海)有限公司 | A kind of microphone device and preparation method thereof |
| US11050012B2 (en) * | 2019-04-01 | 2021-06-29 | Taiwan Semiconductor Manufacturing Co., Ltd. | Method to protect electrodes from oxidation in a MEMS device |
| CN112929804A (en) * | 2021-04-02 | 2021-06-08 | 瑞声声学科技(深圳)有限公司 | MEMS microphone chip |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111800716A (en) * | 2020-07-03 | 2020-10-20 | 安徽奥飞声学科技有限公司 | A kind of MEMS structure and its forming method |
| CN113264500A (en) * | 2021-04-27 | 2021-08-17 | 歌尔微电子股份有限公司 | Micro-electromechanical device, manufacturing method thereof and electronic equipment |
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