CN107398780B - Double-side polishing method for wafer - Google Patents
Double-side polishing method for wafer Download PDFInfo
- Publication number
- CN107398780B CN107398780B CN201610332985.7A CN201610332985A CN107398780B CN 107398780 B CN107398780 B CN 107398780B CN 201610332985 A CN201610332985 A CN 201610332985A CN 107398780 B CN107398780 B CN 107398780B
- Authority
- CN
- China
- Prior art keywords
- polishing
- wafer
- solution
- double
- rough
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B39/00—Burnishing machines or devices, i.e. requiring pressure members for compacting the surface zone; Accessories therefor
- B24B39/06—Burnishing machines or devices, i.e. requiring pressure members for compacting the surface zone; Accessories therefor designed for working plane surfaces
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/30625—With simultaneous mechanical treatment, e.g. mechanico-chemical polishing
Abstract
The invention provides a double-side polishing method of a wafer, which comprises the following steps: s1: loading the wafer into the notch of the carrier disc and placing the wafer between an upper polishing disc covered with an upper polishing pad and a lower polishing disc covered with a lower polishing pad; s2: supplying polishing liquid between the wafer and the upper polishing pad and the lower polishing pad, polishing the front surface and the back surface of the wafer, and forming a polymer film on the back surface of the wafer; s3: and supplying deionized water between the wafer and the upper polishing pad and the lower polishing pad to remove polishing liquid on the wafer, the upper polishing pad and the lower polishing pad. According to the invention, the polymer film can be formed on the back surface of the wafer in the double-side polishing process, so that the back surface of the wafer is effectively isolated from the high-alkali rough polishing solution remained in the rough polishing step, and the back surface of the wafer is isolated from a chemical reagent adopted in subsequent hydrophilic treatment, thereby inhibiting the etching of the back surface of the wafer and improving the quality of a local light scattering body on the back surface of the wafer and the roughness quality.
Description
Technical Field
The invention belongs to the field of semiconductor manufacturing, and relates to a double-side polishing method for a wafer.
Background
Semiconductor wafers are generally derived from a single crystal ingot, and after grinding, cleaning and etching steps are performed on semiconductor chips cut from the single crystal ingot, the surfaces of the semiconductor chips are polished by polishing.
Generally, in order to realize the polishing precision of silicon wafers and achieve the technical indexes required by integrated circuit silicon wafers, two-step polishing is required: rough polishing and fine polishing. The rough polishing process typically includes polishing of the front and back surfaces of the wafer, and the fine polishing process typically only targets the front surface of the wafer. When the surface of the silicon wafer is subjected to the step-by-step chemical mechanical polishing, the polishing solution and the corresponding polishing process conditions used in each step of polishing are different, and the processing precision of the corresponding silicon wafer in each step is also different. In the rough polishing step, the surface damage layer remained after cutting and shaping of the silicon wafer is removed, the silicon wafer is processed into a mirror surface, and finally the silicon wafer is subjected to fine polishing through defogging, so that the surface roughness and other micro defects are reduced to the maximum extent.
In the case of Single-Side Polishing (SSP), the semiconductor wafer is held on its back Side on a support plate by gluing, vacuum or by gluing during processing and is polished on the other Side. In the case of Double Side Polishing (DSP), semiconductor wafers are loosely inserted into a thin carrier plate (carrier) and are simultaneously polished on the front and back sides in a "free-floating" manner between an upper polishing disk and a lower polishing disk, each covered by a polishing pad (pad). The polishing process is carried out by providing a polishing agent slurry, typically based on a silica sol. The prior art also discloses the use of fixed-bond abrasives ("fixed-abrasive polishing," FAP), wherein a semiconductor wafer is polished on a polishing pad that differs from other polishing pads in that it contains an abrasive material bonded in the polishing pad ("fixed-abrasive" or FA pad). German patent application DE102007035266a1 describes a method for polishing substrates composed of silicon material using FA pads.
Synchronous double-side polishing (DSP) of semiconductor wafers is not only more economical than single-side polishing (SSP), but also results in higher flatness in terms of the semiconductor wafer surface.
Polishing Slurry (Slurry) is one of the key elements in the polishing process, and the performance of the Slurry directly affects the quality of the polished wafer surface. The polishing slurry is typically composed of an ultra-fine solid particle abrasive (e.g., nano-SiO)2、Al2O3Particles, etc.), surfactants, stabilizers, oxidizing agents, etc. The solid particles provide the abrasive action and the chemical oxidizing agent provides the corrosive dissolution action.
The existing double-sided polishing process comprises the following steps: (1) the upper fixed disc descends to contact with the lower fixed disc, and then pressurization and fixed disc rotation are carried out; (2) and (3) preliminary removal: removing a natural oxide layer by adopting a circulating coarse polishing solution; (3) removing a main body: removing a preset polishing amount by adopting a circulating coarse polishing solution; (4) washing with deionized water: controlling the contact of the rough polishing solution in the previous step; (5) surfactant treatment: making the surface of the wafer hydrophilic, and controlling the roughness and the nano quality; (6) removing the surfactant from the polishing pad and inhibiting patterning of the polishing pad.
In the conventional double-side polishing process, due to the influence of a high PH value of a rough polishing solution (stock slurry), the high-alkali rough polishing solution remaining on a fixed-plate polishing pad after processing may cause a phenomenon of wafer surface corrosion, and deteriorate the wafer roughness and the quality of a Local Light Scattering (LLS). In particular, the LLS and roughness quality of the back surface of the wafer, which is in contact with the polishing pad of the lower surface plate, tend to be inferior to the front surface of the wafer.
Therefore, how to provide a double-side polishing method for a wafer to reduce the corrosion of the back side of the polished wafer and improve the LLS and the roughness of the wafer becomes an important technical problem to be solved by those skilled in the art.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a method for polishing both sides of a wafer, which is used to solve the problem of the prior art that the roughness quality and the LLS quality of the wafer are reduced due to the corrosion of the back side of the wafer caused by the residue of the highly alkaline rough polishing solution.
To achieve the above and other related objects, the present invention provides a double-side polishing method for a wafer, comprising the steps of:
s1: loading the wafer into the notch of the carrier disc and placing the wafer between an upper polishing disc covered with an upper polishing pad and a lower polishing disc covered with a lower polishing pad;
s2: supplying polishing liquid between the wafer and the upper polishing pad and the lower polishing pad, polishing the front surface and the back surface of the wafer, and forming a polymer film on the back surface of the wafer;
s3: and supplying deionized water between the wafer and the upper polishing pad and the lower polishing pad to remove polishing liquid on the wafer, the upper polishing pad and the lower polishing pad.
Optionally, the step S2 includes:
s2-1: supplying rough polishing liquid to perform rough polishing on the wafer in a first polishing stage, and removing an oxide layer on the surface of the wafer;
s2-2: supplying rough polishing liquid to perform rough polishing on the wafer in the second polishing stage, and removing a preset amount of wafer materials;
s2-3: stopping supplying the coarse polishing solution and supplying the fine polishing solution to perform fine polishing on the wafer in the third polishing stage; the fine polishing solution contains a polymer, and the polymer is bonded to the back surface of the wafer in the fine polishing process to form the polymer film.
Optionally, the abrasive in the rough polishing solution comprises one or more of silicon oxide, aluminum oxide and cerium oxide; the abrasive in the fine polishing solution comprises one or more of silicon oxide, aluminum oxide and cerium oxide, or the fine polishing solution is a polishing agent solution without the abrasive.
Optionally, in the step S2-1 and the step S2-2, both the rough polishing solution and the recycled rough polishing solution are recycled; in the step S2-3, the fine polishing liquid does not enter circulation.
Optionally, the pH value of the circulating coarse polishing solution is maintained within the range of 10.5-11 by adding KOH.
Optionally, in the step S2-1, the polishing pressure applied to the wafer ranges from 0.01 to 0.20daN/cm2Polishing for 1-5 min; in the step S2-2, the polishing pressure applied to the wafer is in the range of 0.01 to 0.20daN/cm2The polishing time is 20-40 min; in the step S2-3, the polishing pressure applied to the wafer is in the range of 0.01 to 0.05daN/cm2And the polishing time is 1-5 min.
Optionally, in the step S2-1, S2-2, or S2-3, the rotation speed of the upper polishing disk is 20 to 40rpm, and the rotation speed of the lower polishing disk is-10 to-40 rpm.
Optionally, the step S2 includes:
s2-1: supplying rough polishing liquid to polish the wafer in a first polishing stage, and removing an oxide layer on the surface of the wafer;
s2-2: supplying rough polishing liquid to polish the wafer in the second polishing stage, and removing a preset amount of wafer materials;
s2-3: and supplying a coarse polishing solution added with a water-soluble polymer to polish the wafer in the third polishing stage, wherein the polymer is bonded to the back surface of the wafer during polishing to form the polymer film.
Optionally, in the step S2-3, the addition amount of the water-soluble polymer is less than 1 wt%, and the viscosity of the rough polishing solution is 5 to 15cps after the water-soluble polymer is added.
Optionally, the abrasive in the rough polishing solution comprises one or more of silicon oxide, aluminum oxide and cerium oxide.
Optionally, in the step S2-1 and the step S2-2, both the rough polishing solution and the recycled rough polishing solution are recycled; in the step S2-3, the coarse polishing solution to which the water-soluble polymer is added does not enter circulation.
Optionally, the step S2 includes:
s2-1: supplying rough polishing liquid to polish the wafer in a first polishing stage, and removing an oxide layer on the surface of the wafer;
s2-2: supplying a coarse polishing solution and a fine polishing solution to polish the wafer at the second stage of polishing, and removing a preset amount of wafer materials; the fine polishing solution contains a polymer, and the polymer is bonded to the back surface of the wafer in the polishing process to form the polymer film.
Optionally, the abrasive in the rough polishing solution or the fine polishing solution comprises one or more of silicon oxide, aluminum oxide and cerium oxide.
Optionally, the step S2 includes:
s2-1: supplying a coarse polishing solution and a fine polishing solution to polish the wafer at the first polishing stage, and removing an oxide layer on the surface of the wafer;
s2-2: supplying a coarse polishing solution and a fine polishing solution to polish the wafer at the second stage of polishing, and removing a preset amount of wafer materials; the fine polishing solution contains a polymer, and the polymer is bonded to the back surface of the wafer in the polishing process to form the polymer film.
Optionally, the abrasive in the rough polishing solution or the fine polishing solution comprises one or more of silicon oxide, aluminum oxide and cerium oxide.
Optionally, the method further includes step S4: and supplying a surfactant solution between the wafer and the upper polishing pad and the lower polishing pad to hydrophilize the surface of the wafer.
Optionally, the method further includes step S5: and lifting the upper polishing disk, unloading the wafer from the space between the upper polishing disk and the lower polishing disk, and removing the residual surfactant on the upper polishing pad and the lower polishing pad by adopting a high-pressure plasma water jet method.
Optionally, the polymer comprises one or more of guar gum, xanthan gum, cellulose acetate, ethyl cellulose sulfonate, carboxymethyl hydroxyethyl cellulose, methyl cellulose, carboxyethyl methyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl methyl cellulose, hydroxyethyl cellulose.
As described above, the double-side polishing method of a wafer according to the present invention has the following advantageous effects: the double-side polishing method of the wafer adds a fine polishing step between the conventional rough polishing process and the deionized water cleaning process, wherein the fine polishing step uses a fine polishing solution, the polishing pressure is 10-50% of the polishing pressure of the previous rough polishing step, and local light scatterer particles on the back surface of the wafer are removed within 5 minutes. Particularly, in the fine polishing step, the polymer in the fine polishing solution can form a polymer film on the back surface of the wafer, and the polymer film can effectively isolate the back surface of the wafer from the high-alkali coarse polishing solution remained in the coarse polishing step and isolate the back surface of the wafer from a chemical reagent adopted in subsequent hydrophilic treatment, so that the etching of the back surface of the wafer is inhibited, and the quality of a local light scattering body on the back surface of the wafer and the quality of roughness are improved. The invention can also adopt the coarse polishing solution added with the water-soluble polymer to replace the fine polishing solution in the fine polishing step, thereby being beneficial to reducing the cost. In addition, the present invention can also supply the fine polishing solution containing the polymer while supplying the coarse polishing solution in the conventional coarse polishing process without adding the fine polishing step, thereby achieving similar technical effects.
Drawings
Fig. 1-2 show process flow diagrams of the method for double-side polishing of a wafer according to the present invention.
FIG. 3 is a flowchart illustrating a method of polishing both sides of a wafer according to a first embodiment of the present invention.
FIG. 4 is a flowchart illustrating a method of double-side polishing a wafer according to a third embodiment of the present invention.
FIG. 5 is a flowchart illustrating a method of double-side polishing a wafer according to a fourth embodiment of the present invention.
FIG. 6 is a flowchart illustrating a method of double-side polishing a wafer according to a fifth embodiment of the present invention.
Description of the element reference numerals
S1-S5, S2-1-S2-3
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Please refer to fig. 1 to 6. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
The present invention provides a method for polishing both sides of a wafer, referring to fig. 1, which is a process flow diagram of the method, comprising the following steps:
step S1: the wafer is loaded into the cutout of the carrier plate and placed between the upper polishing plate covered with the upper polishing pad and the lower polishing plate covered with the lower polishing pad.
By way of example, the upper polishing pad and the lower polishing pad are made of the same material, the front surface of the wafer is in contact with the upper polishing pad, and the back surface of the wafer is in contact with the lower polishing pad.
Step S2: and supplying polishing liquid between the wafer and the upper polishing pad and the lower polishing pad, polishing the front surface and the back surface of the wafer, and forming a polymer film on the back surface of the wafer.
Specifically, the step is used for polishing the front side and the back side of the wafer on one hand, and forming a polymer film on the back side of the wafer during the polishing process on the other hand.
Specifically, the polishing in this step can be divided into a plurality of stages, and the polishing solution and the corresponding polishing conditions used in each stage of polishing can be different to achieve the required polishing precision. The polymer material forming the polymer film in this step may be derived from a polishing liquid used at any stage of polishing.
By way of example, the polymer includes, but is not limited to, one or more of guar gum, xanthan gum, cellulose acetate, sulfoethyl cellulose, carboxymethyl hydroxyethyl cellulose, methyl cellulose, carboxyethyl methyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl methyl cellulose, hydroxyethyl cellulose.
According to the invention, the polymer film can effectively isolate the back surface of the wafer from the high-alkali coarse polishing solution remained in the coarse polishing step, and isolate the back surface of the wafer from a chemical reagent adopted in subsequent hydrophilization treatment, so that the back surface of the wafer is inhibited from being continuously etched by the remained high-alkali polishing solution or the chemical reagent after polishing, and the quality of a local light scattering body on the back surface of the wafer and the quality of roughness are improved.
It should be noted that the polymer film may be formed on the back surface and the front surface of the wafer at the same time, but in general, the back surface of the wafer is not polished after the double-side polishing process, and the front surface of the wafer undergoes the subsequent fine polishing stage, so that the polymer film formed on the front surface of the wafer has little significance for improving the quality of the front surface of the final wafer, and the polymer film formed on the back surface of the wafer is crucial for the roughness quality of the back surface of the wafer and the number parameter of the local light scattering body particles.
Step S3: and supplying deionized water between the wafer and the upper polishing pad and the lower polishing pad to remove polishing liquid on the wafer, the upper polishing pad and the lower polishing pad.
Specifically, the deionized water cleaning in this step can remove most of the polishing solution remaining on the wafer, the upper polishing pad, and the lower polishing pad, thereby providing a relatively clean processing environment for the subsequent steps. Due to the existence of the polymer film, even though unremoved polishing liquid still remains in the upper polishing pad and the lower polishing pad, alkali in the polishing liquid is difficult to react with silicon on the back surface of the wafer, so that re-corrosion of the back surface of the wafer is reduced.
For example, in the deionized water cleaning process in the step, the processing load is 0.01 to 0.05daN/cm2The processing time is 1-5 min.
Further, referring to fig. 2, the method for polishing both sides of a wafer according to the present invention further includes step S4: and supplying a surfactant solution between the wafer and the upper polishing pad and the lower polishing pad to hydrophilize the surface of the wafer.
Specifically, the step of hydrophilizing the wafer surface can improve the roughness quality and Nano (Nano) quality of the wafer surface. The surface active agent has the characteristics of adsorption, wetting, penetration, dispersion, solubilization and the like, and the root cause of reducing the surface tension of the liquid is to form a directional adsorption layer on the surface of the water through adsorption, replace water molecules with strong intermolecular force by hydrophobic groups with weak intermolecular force, reduce the contact area of air and water and further reduce the surface tension of the water sharply. In order to avoid ionic contamination, nonionic surfactant types are used in this step, and are classified into polyhydric alcohol type and polyether alcohol type from the viewpoint of hydrophilic group, and the polyhydric amine alcohol type surfactant has excellent emulsifying, solubilizing, wetting, diffusing, penetrating and antistatic capabilities.
Further, the double-side polishing method of a wafer of the present invention further includes step S5: and lifting the upper polishing disk, unloading the wafer from the space between the upper polishing disk and the lower polishing disk, and removing the residual surfactant on the upper polishing pad and the lower polishing pad by adopting a high-pressure plasma water jet method.
Specifically, in addition to removing the residual surfactant on the upper polishing pad and the lower polishing pad, the high-pressure plasma water jet can further remove the residual surfactant on the upper polishing pad and the lower polishing pad. After the polishing pad is polished for a period of time, some polishing particles, polishing liquid crystals and polishing pad residues are embedded in the grooves of the polishing pad, which affect the distribution of the polishing liquid on the polishing pad and scratch the surface of the polished wafer silicon wafer, affect the yield of the final finished product and even cause the rejection of the finished product. Therefore, a high pressure DI water rinse is required to rinse away the residue remaining in the grooves of the polishing pad so that the pad functions.
Therefore, the double-side polishing of the wafer is completed by the method, and the front side fine polishing process of the wafer can be further carried out subsequently.
The following are several application examples of the method for double-side polishing of a wafer of the present invention.
Example one
The present invention provides a method for polishing both sides of a wafer, referring to fig. 3, which is a process flow diagram of the method, comprising the steps of:
s1: loading the wafer into the notch of the carrier disc and placing the wafer between an upper polishing disc covered with an upper polishing pad and a lower polishing disc covered with a lower polishing pad;
s2-1: supplying rough polishing liquid to perform rough polishing on the wafer in a first polishing stage, and removing an oxide layer on the surface of the wafer;
s2-2: supplying rough polishing liquid to perform rough polishing on the wafer in the second polishing stage, and removing a preset amount of wafer materials;
s2-3: stopping supplying the coarse polishing solution and supplying the fine polishing solution to perform fine polishing on the wafer in the third polishing stage; the fine polishing solution contains a polymer, and the polymer is bonded to the back surface of the wafer in the fine polishing process to form the polymer film.
S3: and supplying deionized water between the wafer and the upper polishing pad and the lower polishing pad to remove polishing liquid on the wafer, the upper polishing pad and the lower polishing pad.
S4: supplying a surfactant solution between the wafer and the upper and lower polishing pads to hydrophilize the wafer surface;
s5: and lifting the upper polishing disk, unloading the wafer from the space between the upper polishing disk and the lower polishing disk, and removing the residual surfactant on the upper polishing pad and the lower polishing pad by adopting a high-pressure plasma water jet method.
In this embodiment, the step S2 is divided into three polishing stages, wherein the first two stages are the same as the conventional wafer double-side rough polishing process, and both use rough polishing liquid to remove the oxide layer on the wafer surface and remove a predetermined amount of wafer material, for example, the predetermined amount is greater than 10 μm thick. And the third stage is an additional step of the invention, which is equivalent to adding a fine polishing step between the conventional rough polishing process and the deionized water cleaning process, wherein the fine polishing step uses fine polishing liquid. In the fine polishing step, the polymer in the fine polishing solution can form a polymer film on the back surface of the wafer, and the polymer film can effectively isolate the back surface of the wafer from the high-alkali coarse polishing solution remained in the coarse polishing step and isolate the back surface of the wafer from a chemical reagent adopted in subsequent hydrophilization treatment, so that the etching of the back surface of the wafer is inhibited, and the quality of a local light scattering body on the back surface of the wafer and the quality of roughness are improved.
Specifically, the difference between the fine polishing solution and the rough polishing solution is that the fine polishing solution contains a polymer. By way of example, the abrasive in the rough polishing solution includes but is not limited to one or more of silicon oxide, aluminum oxide and cerium oxide, and the average particle size of the abrasive is in the range of 10-100 nm; the abrasive in the fine polishing solution includes but is not limited to one or more of silicon oxide, aluminum oxide and cerium oxide, and the average grain size of the abrasive is 30-60 nm. The polymer in the fine polishing solution includes, but is not limited to, one or more of guar gum, xanthan gum, cellulose acetate, sulfonic ethyl cellulose, carboxymethyl hydroxyethyl cellulose, methyl cellulose, carboxyethyl methyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl methyl cellulose, hydroxyethyl cellulose.
Of course, the rough polishing solution and the fine polishing solution also include water, surfactant, alkaline compound, etc., which are well known to those skilled in the art, and the scope of the present invention should not be limited too much.
For example, in the step S2-1 and the step S2-2, the rough polishing solution is a circulating rough polishing solution; the pH value of the circulating coarse polishing solution can be maintained within the range of 10.5-11 by adding KOH. In step S2-3, the fine polishing solution is not circulated, i.e., new fine polishing solution is continuously supplied, and the waste fine polishing solution is not reused in this step.
For example, in the step S2-1, the polishing pressure applied to the wafer is in the range of 0.01 to 0.20daN/cm2Polishing for 1-5 min; in the step S2-2, the polishing pressure applied to the wafer is in the range of 0.01 to 0.20daN/cm2The polishing time is 20-40 min; in the step S2-3, the polishing pressure applied to the wafer is in the range of 0.01 to 0.05daN/cm2Preferably, the polishing pressure is 10-50% of the polishing pressure of the previous rough polishing step, and the polishing time is 1-5 min.
For example, in the step S2-1, S2-2 or S2-3, the rotation speed of the upper polishing disk is 20 to 40rpm, and the rotation speed of the lower polishing disk is-10 to-40 rpm.
According to the double-side polishing method of the wafer, a fine polishing step is added between a conventional rough polishing process and a deionized water cleaning process, fine polishing liquid is used in the fine polishing step, the polishing pressure is 10-50% of that of the previous rough polishing step, and local light scatterer particles on the back surface of the wafer are removed within 5 minutes. Particularly, in the fine polishing step, the polymer in the fine polishing solution can form a polymer film on the back surface of the wafer, and the polymer film can effectively isolate the back surface of the wafer from the high-alkali coarse polishing solution remained in the coarse polishing step and isolate the back surface of the wafer from a chemical reagent adopted in subsequent hydrophilic treatment, so that the etching of the back surface of the wafer is inhibited, and the quality of a Local Light Scattering (LLS) and the roughness quality of the back surface of the wafer are improved.
Example two
The present example is basically the same as the first example, except that in the first example, the fine polishing solution used in step S2-3 contains an abrasive, whereas in the present example, the fine polishing solution used in step S2-3 is a polishing agent solution that does not contain an abrasive.
Since the main role of step S2-3 is to form a polymer film on the back surface of the wafer, this object can be achieved even if the fine polishing liquid does not contain an abrasive. In addition, the steps S2-1 and S2-2 may also leave a lot of abrasive particles on the surface of the polishing pad and the wafer, and the polishing agent solution is combined with the abrasive particles, which may also serve the purpose of removing the local light scatterer particles in the step S2-3 in the first embodiment.
EXAMPLE III
The present invention provides a method for polishing both sides of a wafer, referring to fig. 4, which is a process flow diagram of the method, comprising the steps of:
s1: loading the wafer into the notch of the carrier disc and placing the wafer between an upper polishing disc covered with an upper polishing pad and a lower polishing disc covered with a lower polishing pad;
s2-1: supplying rough polishing liquid to polish the wafer in a first polishing stage, and removing an oxide layer on the surface of the wafer;
s2-2: supplying rough polishing liquid to polish the wafer in the second polishing stage, and removing a preset amount of wafer materials;
s2-3: and supplying a coarse polishing solution added with a water-soluble polymer to polish the wafer in the third polishing stage, wherein the polymer is bonded to the back surface of the wafer during polishing to form the polymer film.
S3: and supplying deionized water between the wafer and the upper polishing pad and the lower polishing pad to remove polishing liquid on the wafer, the upper polishing pad and the lower polishing pad.
S4: supplying a surfactant solution between the wafer and the upper and lower polishing pads to hydrophilize the wafer surface;
s5: and lifting the upper polishing disk, unloading the wafer from the space between the upper polishing disk and the lower polishing disk, and removing the residual surfactant on the upper polishing pad and the lower polishing pad by adopting a high-pressure plasma water jet method.
The difference between this embodiment and the first and second embodiments is that in the fine polishing step of step S2-3, the coarse polishing solution added with the water-soluble polymer is used instead of the fine polishing solution, which is beneficial to reducing the cost.
For example, in the step S2-3, the addition amount of the water-soluble polymer is less than 1 wt%, and the viscosity of the rough polishing solution is 5 to 15cps after the water-soluble polymer is added. The abrasive in the rough polishing solution comprises one or more of silicon oxide, aluminum oxide and cerium oxide.
For example, in the step S2-1 and the step S2-2, the rough polishing solution is a circulating rough polishing solution; in the step S2-3, the raw material of the coarse polishing solution added with the water-soluble polymer may be a new coarse polishing solution, or a previously circulated coarse polishing solution, but after polishing, the coarse polishing solution added with the water-soluble polymer is not circulated again, so as to avoid interference with steps S2-1 and S2-2 in other wafer polishing processes.
The double-side polishing method of the wafer in the embodiment can achieve the technical effects basically the same as those of the first embodiment and the second embodiment, the polymer film is formed on the back surface of the wafer, and the polymer film can effectively isolate the back surface of the wafer from the high-alkali rough polishing solution remained in the rough polishing step and isolate the back surface of the wafer from a chemical reagent adopted in subsequent hydrophilic treatment, so that the etching of the back surface of the wafer is inhibited, and the quality of a local light scattering body and the roughness quality of the back surface of the wafer are improved.
Example four
The present invention provides a method for polishing both sides of a wafer, referring to fig. 5, which is a process flow diagram of the method, comprising the steps of:
s1: loading the wafer into the notch of the carrier disc and placing the wafer between an upper polishing disc covered with an upper polishing pad and a lower polishing disc covered with a lower polishing pad;
s2-1: supplying rough polishing liquid to polish the wafer in a first polishing stage, and removing an oxide layer on the surface of the wafer;
s2-2: supplying a coarse polishing solution and a fine polishing solution to polish the wafer at the second stage of polishing, and removing a preset amount of wafer materials; the fine polishing solution contains a polymer, and the polymer is bonded to the back surface of the wafer in the polishing process to form the polymer film.
S3: and supplying deionized water between the wafer and the upper polishing pad and the lower polishing pad to remove polishing liquid on the wafer, the upper polishing pad and the lower polishing pad.
S4: supplying a surfactant solution between the wafer and the upper and lower polishing pads to hydrophilize the wafer surface;
s5: and lifting the upper polishing disk, unloading the wafer from the space between the upper polishing disk and the lower polishing disk, and removing the residual surfactant on the upper polishing pad and the lower polishing pad by adopting a high-pressure plasma water jet method.
The present embodiment is different from the first, second, and third embodiments in that the present embodiment can simultaneously supply the rough polishing solution and the fine polishing solution containing a polymer in the second polishing stage without adding the fine polishing step.
By way of example, the abrasive in the rough polishing solution or the fine polishing solution includes, but is not limited to, one or more of silicon oxide, aluminum oxide, and cerium oxide.
The step S2-2 is a main process flow of wafer double-side polishing, and is used for removing a predetermined amount of wafer material. Since the rough polishing solution and the fine polishing solution are supplied at the same time in step S2-2, the presence of the polymer in the polishing solution reduces the chemical and mechanical effects between the alkali and abrasive in the polishing solution and the wafer, so that the polishing speed of this embodiment is reduced, but the polishing quality is improved, compared to the first, second and third embodiments, and a polymer layer can be formed on the back surface of the wafer, thereby effectively isolating the back surface of the wafer from the high-alkali rough polishing solution remaining in the rough polishing step, and isolating the back surface of the wafer from the chemical agent used in the subsequent hydrophilization treatment, thereby inhibiting the etching of the back surface of the wafer, and improving the quality of local light scatterers and roughness on the back surface of the wafer.
EXAMPLE five
The present invention provides a method for polishing both sides of a wafer, referring to fig. 6, which is a process flow diagram of the method, comprising the steps of:
s1: loading the wafer into the notch of the carrier disc and placing the wafer between an upper polishing disc covered with an upper polishing pad and a lower polishing disc covered with a lower polishing pad;
s2-1: supplying a coarse polishing solution and a fine polishing solution to polish the wafer at the first polishing stage, and removing an oxide layer on the surface of the wafer;
s2-2: supplying a coarse polishing solution and a fine polishing solution to polish the wafer at the second stage of polishing, and removing a preset amount of wafer materials; the fine polishing solution contains a polymer, and the polymer is bonded to the back surface of the wafer in the polishing process to form the polymer film.
S3: and supplying deionized water between the wafer and the upper polishing pad and the lower polishing pad to remove polishing liquid on the wafer, the upper polishing pad and the lower polishing pad.
S4: supplying a surfactant solution between the wafer and the upper and lower polishing pads to hydrophilize the wafer surface;
s5: and lifting the upper polishing disk, unloading the wafer from the space between the upper polishing disk and the lower polishing disk, and removing the residual surfactant on the upper polishing pad and the lower polishing pad by adopting a high-pressure plasma water jet method.
The present embodiment adopts substantially the same technical solution as the fourth embodiment, except that in the present embodiment, the step S2-1 and the step S2-2 both supply the rough polishing solution and the fine polishing solution at the same time, so as to achieve the similar technical effect as the fourth embodiment.
In summary, the double-side polishing method of the wafer of the present invention adds a fine polishing step between the conventional rough polishing process and the deionized water cleaning process, wherein the fine polishing step uses a fine polishing solution, the polishing pressure is 10-50% of the polishing pressure of the previous rough polishing step, and the local light scatterer particles on the back side of the wafer are removed within 5 minutes. Particularly, in the fine polishing step, the polymer in the fine polishing solution can form a polymer film on the back surface of the wafer, and the polymer film can effectively isolate the back surface of the wafer from the high-alkali coarse polishing solution remained in the coarse polishing step and isolate the back surface of the wafer from a chemical reagent adopted in subsequent hydrophilic treatment, so that the etching of the back surface of the wafer is inhibited, and the quality of a local light scattering body on the back surface of the wafer and the quality of roughness are improved. The invention can also adopt the coarse polishing solution added with the water-soluble polymer to replace the fine polishing solution in the fine polishing step, thereby being beneficial to reducing the cost. In addition, the present invention can also supply the fine polishing solution containing the polymer while supplying the coarse polishing solution in the conventional coarse polishing process without adding the fine polishing step, thereby achieving similar technical effects. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (18)
1. A double-side polishing method of a wafer is characterized by comprising the following steps:
s1: loading the wafer into the notch of the carrier disc and placing the wafer between an upper polishing disc covered with an upper polishing pad and a lower polishing disc covered with a lower polishing pad;
s2: supplying polishing liquid between the wafer and the upper polishing pad and the lower polishing pad, polishing the front surface and the back surface of the wafer, and forming a polymer film on the back surface of the wafer, wherein the polishing at least comprises two stages, the polishing liquid adopted in the final stage of the polishing contains polymer and does not contain abrasive, the polymer is bonded on the back surface of the wafer during the polishing process to form the polymer film, and the polymer film is used for isolating the back surface of the wafer from the coarse polishing liquid remained in the coarse polishing step of the previous stage;
s3: and supplying deionized water between the wafer and the upper polishing pad and the lower polishing pad to remove polishing liquid on the wafer, the upper polishing pad and the lower polishing pad.
2. The double-side polishing method of a wafer according to claim 1, characterized in that: the step S2 includes:
s2-1: supplying rough polishing liquid to perform rough polishing on the wafer in a first polishing stage, and removing an oxide layer on the surface of the wafer;
s2-2: supplying rough polishing liquid to perform rough polishing on the wafer in the second polishing stage, and removing a preset amount of wafer materials;
s2-3: stopping supplying the coarse polishing solution and supplying the fine polishing solution to perform fine polishing on the wafer in the third polishing stage; the fine polishing solution contains a polymer, and the polymer is bonded to the back surface of the wafer in the fine polishing process to form the polymer film.
3. A double-side polishing method for a wafer according to claim 2, characterized in that: the abrasive in the rough polishing solution comprises one or more of silicon oxide, aluminum oxide and cerium oxide; the fine polishing solution is a polishing agent solution containing no abrasive.
4. A double-side polishing method for a wafer according to claim 2, characterized in that: in the step S2-1 and the step S2-2, the rough polishing solution is a circulating rough polishing solution; in the step S2-3, the fine polishing liquid does not enter circulation.
5. A double-side polishing method for a wafer according to claim 4, characterized in that: the pH value of the circulating coarse polishing solution is maintained within the range of 10.5-11 by adding KOH.
6. A double-side polishing method for a wafer according to claim 2, characterized in that: in the step S2-1, the polishing pressure applied to the wafer is in the range of 0.01 to 0.20daN/cm2Polishing for 1-5 min; in the step S2-2, the polishing pressure applied to the wafer is in the range of 0.01 to 0.20daN/cm2The polishing time is 20-40 min; in the step S2-3, the polishing pressure applied to the wafer is in the range of 0.01 to 0.05daN/cm2And the polishing time is 1-5 min.
7. A double-side polishing method for a wafer according to claim 2, characterized in that: in the step S2-1, S2-2 or S2-3, the rotation speed of the upper polishing disk is 20 to 40rpm, and the rotation speed of the lower polishing disk is-10 to-40 rpm.
8. The double-side polishing method of a wafer according to claim 1, characterized in that: the step S2 includes:
s2-1: supplying rough polishing liquid to polish the wafer in a first polishing stage, and removing an oxide layer on the surface of the wafer;
s2-2: supplying rough polishing liquid to polish the wafer in the second polishing stage, and removing a preset amount of wafer materials;
s2-3: and supplying a coarse polishing solution added with a water-soluble polymer to polish the wafer in the third polishing stage, wherein the polymer is bonded to the back surface of the wafer during polishing to form the polymer film.
9. A double-side polishing method for a wafer according to claim 8, characterized in that: in the step S2-3, the addition amount of the water-soluble polymer is less than 1 wt%, and the viscosity of the rough polishing solution is 5-15cps after the water-soluble polymer is added.
10. A double-side polishing method for a wafer according to claim 8, characterized in that: in the steps S2-1 and S2-2, the abrasive in the rough polishing solution includes one or more of silicon oxide, aluminum oxide, and cerium oxide, and in the step S2-3, the rough polishing solution added with the water-soluble polymer does not include the abrasive.
11. A double-side polishing method for a wafer according to claim 8, characterized in that: in the step S2-1 and the step S2-2, the rough polishing solution is a circulating rough polishing solution; in the step S2-3, the coarse polishing solution to which the water-soluble polymer is added does not enter circulation.
12. The double-side polishing method of a wafer according to claim 1, characterized in that: the step S2 includes:
s2-1: supplying rough polishing liquid to polish the wafer in a first polishing stage, and removing an oxide layer on the surface of the wafer;
s2-2: supplying a coarse polishing solution and a fine polishing solution to polish the wafer at the second stage of polishing, and removing a preset amount of wafer materials; the fine polishing solution contains a polymer, and the polymer is bonded to the back surface of the wafer in the polishing process to form the polymer film.
13. A double-side polishing method for a wafer according to claim 12, characterized in that: in the step S2-1, the abrasive in the rough polishing solution includes one or more of silicon oxide, aluminum oxide, and cerium oxide, and in the step S2-2, the rough polishing solution and the fine polishing solution do not include abrasive.
14. The double-side polishing method of a wafer according to claim 1, characterized in that: the step S2 includes:
s2-1: supplying a coarse polishing solution and a fine polishing solution to polish the wafer at the first polishing stage, and removing an oxide layer on the surface of the wafer;
s2-2: supplying a coarse polishing solution and a fine polishing solution to polish the wafer at the second stage of polishing, and removing a preset amount of wafer materials; the fine polishing solution contains a polymer, and the polymer is bonded to the back surface of the wafer in the polishing process to form the polymer film.
15. A method for double-side polishing a wafer according to claim 14, wherein: in step S2-1, the abrasive in the rough polishing solution or the fine polishing solution includes one or more of silicon oxide, aluminum oxide, and cerium oxide; in the step S2-2, the rough polishing solution and the fine polishing solution do not include abrasives.
16. A method for double-side polishing a wafer according to any one of claims 1 to 15, wherein: further comprising step S4: and supplying a surfactant solution between the wafer and the upper polishing pad and the second polishing pad to hydrophilize the surface of the wafer.
17. A method for double-side polishing of a wafer as recited in claim 16, wherein: further comprising step S5: and lifting the upper polishing disk, unloading the wafer from the space between the upper polishing disk and the lower polishing disk, and removing the residual surfactant on the upper polishing pad and the lower polishing pad by adopting a high-pressure plasma water jet method.
18. A method for double-side polishing a wafer according to any one of claims 1 to 15, wherein: the polymer comprises one or more of guar gum, xanthan gum, cellulose acetate, sulfoethyl cellulose, carboxymethyl hydroxyethyl cellulose, methyl cellulose, carboxyethyl methyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl methyl cellulose, hydroxyethyl cellulose.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610332985.7A CN107398780B (en) | 2016-05-18 | 2016-05-18 | Double-side polishing method for wafer |
| TW105133111A TWI614801B (en) | 2016-05-18 | 2016-10-13 | Method for a double side polishing of a semiconductor wafer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610332985.7A CN107398780B (en) | 2016-05-18 | 2016-05-18 | Double-side polishing method for wafer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107398780A CN107398780A (en) | 2017-11-28 |
| CN107398780B true CN107398780B (en) | 2020-03-31 |
Family
ID=60394553
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201610332985.7A Active CN107398780B (en) | 2016-05-18 | 2016-05-18 | Double-side polishing method for wafer |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN107398780B (en) |
| TW (1) | TWI614801B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107932296B (en) * | 2017-12-04 | 2019-07-30 | 中电科技集团重庆声光电有限公司 | Semiconductor wafer back burnishing device |
| TWI732244B (en) * | 2019-07-11 | 2021-07-01 | 昇陽國際半導體股份有限公司 | Wafer polishing method |
| CN112454017A (en) * | 2020-11-25 | 2021-03-09 | 西安奕斯伟硅片技术有限公司 | Silicon wafer polishing method and silicon wafer polishing equipment |
| CN112652526A (en) * | 2020-12-14 | 2021-04-13 | 西安奕斯伟硅片技术有限公司 | Silicon wafer polishing method and silicon wafer |
| CN112658975A (en) * | 2020-12-17 | 2021-04-16 | 江苏集萃精凯高端装备技术有限公司 | Method for grinding flaky lutetium oxide laser crystal |
| CN113001379A (en) * | 2021-03-17 | 2021-06-22 | 天津中环领先材料技术有限公司 | Large-size silicon wafer double-side polishing method |
| CN113941952B (en) * | 2021-11-01 | 2022-12-23 | 徐州领测半导体科技有限公司 | Double-side polishing process of semiconductor wafer |
| CN117245542B (en) * | 2023-11-17 | 2024-01-23 | 苏州博宏源机械制造有限公司 | Wafer double-sided polishing equipment and process |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1714432A (en) * | 2002-12-09 | 2005-12-28 | 第一毛织株式会社 | Slurry composition for secondary polishing of silicon wafer |
| CN101310926A (en) * | 2007-05-22 | 2008-11-26 | 天津晶岭电子材料科技有限公司 | Silicon slice grinding surface roughness control method |
| CN103100965A (en) * | 2013-02-05 | 2013-05-15 | 中国电子科技集团公司第四十六研究所 | InP single crystal wafer twin polishing method and device |
| CN103128649A (en) * | 2011-11-28 | 2013-06-05 | 无锡华润上华科技有限公司 | Chemical machinery polishing method capable of reducing residual slurry |
| CN104015123A (en) * | 2014-06-18 | 2014-09-03 | 蓝思科技股份有限公司 | Double-sided polishing process for sapphire panel |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4668528B2 (en) * | 2003-09-05 | 2011-04-13 | 株式会社フジミインコーポレーテッド | Polishing composition |
| TWI323741B (en) * | 2004-12-16 | 2010-04-21 | K C Tech Co Ltd | Abrasive particles, polishing slurry, and producing method thereof |
| KR100979243B1 (en) * | 2008-04-29 | 2010-08-31 | 주식회사 하이닉스반도체 | Semiconductor device and method of manufacturing the same |
| JP5614397B2 (en) * | 2011-11-07 | 2014-10-29 | 信越半導体株式会社 | Double-side polishing method |
| US10317197B2 (en) * | 2012-05-09 | 2019-06-11 | Koninklijke Philips N.V. | System and method for stabilizing optical shape sensing |
-
2016
- 2016-05-18 CN CN201610332985.7A patent/CN107398780B/en active Active
- 2016-10-13 TW TW105133111A patent/TWI614801B/en active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1714432A (en) * | 2002-12-09 | 2005-12-28 | 第一毛织株式会社 | Slurry composition for secondary polishing of silicon wafer |
| CN101310926A (en) * | 2007-05-22 | 2008-11-26 | 天津晶岭电子材料科技有限公司 | Silicon slice grinding surface roughness control method |
| CN103128649A (en) * | 2011-11-28 | 2013-06-05 | 无锡华润上华科技有限公司 | Chemical machinery polishing method capable of reducing residual slurry |
| CN103100965A (en) * | 2013-02-05 | 2013-05-15 | 中国电子科技集团公司第四十六研究所 | InP single crystal wafer twin polishing method and device |
| CN104015123A (en) * | 2014-06-18 | 2014-09-03 | 蓝思科技股份有限公司 | Double-sided polishing process for sapphire panel |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107398780A (en) | 2017-11-28 |
| TWI614801B (en) | 2018-02-11 |
| TW201742135A (en) | 2017-12-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107398780B (en) | Double-side polishing method for wafer | |
| TWI567811B (en) | Verfahren zum beidseitigen polieren einer halbleiterscheibe | |
| TWI285924B (en) | Method for manufacturing silicon wafer | |
| KR101862139B1 (en) | Method for manufacturing semiconductor wafer | |
| TWI616940B (en) | Method for the polishing of a semiconductor wafer | |
| CN107155368B (en) | Method for polishing silicon wafer | |
| EP1852899A1 (en) | Method for manufacturing semiconductor wafer and method for mirror chamfering semiconductor wafer | |
| KR20000017512A (en) | Method for reclaiming wafer substrate and polishing solution composition for reclaiming wafer substrate | |
| CN111251163B (en) | Processing method for polished silicon wafer with hydrophilic surface | |
| US20090130960A1 (en) | Method For Producing A Semiconductor Wafer With A Polished Edge | |
| CN102528597A (en) | Manufacturing process of large-diameter silicon wafer | |
| CN112701037A (en) | Polishing method of semiconductor material and polishing solution for polishing gallium antimonide substrate | |
| CN104827592A (en) | Processing method of large-sized sapphire substrate slice | |
| KR100690098B1 (en) | Semiconductor wafer polishing method and semiconductor wafer polishing device | |
| CN102059640B (en) | Method for polishing semiconductor wafer | |
| JP4085356B2 (en) | Cleaning and drying method for semiconductor wafer | |
| KR102287116B1 (en) | Silicon Wafer Double-Sided Polishing Method | |
| Pei et al. | An experimental investigation into soft-pad grinding of wire-sawn silicon wafers | |
| JP3943869B2 (en) | Semiconductor wafer processing method and semiconductor wafer | |
| JP2007027488A (en) | Method for polishing semiconductor wafer | |
| CN116246949A (en) | Preparation method of single-sided indium phosphide wafer | |
| KR100728887B1 (en) | Method of polishing double side of silicon wafer | |
| KR102172311B1 (en) | Method for forming a protective film on a semiconductor substrate | |
| JPH11243072A (en) | Rising liquid at end of polishing of semiconductor substrate and rinsing method using the liquid | |
| JPH11330024A (en) | Grinding reaction stopper at grinding end for semiconductor substrate and grinding stopping method using the same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |