Ultrathin ultrasonic fingerprint chip and packaging method thereof

Abstract

The invention relates to the field of semiconductors, and discloses an ultrathin ultrasonic fingerprint chip and a packaging method thereof, and the method comprises the steps: obtaining a to-be-segmented ultrathin chip array; the ultra-thin chip array to be segmented comprises a wafer and a plurality of ultra-thin ultrasonic fingerprint chip modules located on the upper surface of the wafer, and each ultra-thin ultrasonic fingerprint chip module comprises an ultrasonic transmitting part, an ultrasonic receiving part, a polarization layer and an electrode. Manufacturing a mask layer on the surface of the ultrathin chip array to be segmented, and removing the mask layer between the adjacent ultrathin ultrasonic fingerprint chip modules to form a segmentation channel; and etching the wafer corresponding to the segmentation channel by adopting a dry etching process, and removing the mask layer to obtain a plurality of ultrathin ultrasonic fingerprint chips which are separated from one another. And the dry etching process is adopted for segmentation, so that the cracking risk caused by physical contact during cutter wheel cutting can be avoided, and the reliability and the packaging yield are improved. According to the invention, a plurality of ultrathin ultrasonic fingerprint chip modules are formed on one wafer, so that the packaging efficiency can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductors, and in particular to an ultrathin ultrasonic fingerprint chip and a packaging method thereof. BACKGROUND

[0002] An ultrasonic fingerprint chip is a kind of biometric sensor based on ultrasonic imaging principle, which captures the 3D structural features (such as ridges, sweat pores and subcutaneous tissues) of fingerprints by transmitting high-frequency sound waves through the screen or shell, and realizes high-security identity authentication.

[0003] At present, the ultrasonic fingerprint chip is usually packaged by means of patch packaging. First, a single chip is obtained by a separation process, and then the single chip is fixed on a circuit board by an adhesive. The separation of single chips usually adopts a cutter wheel for cutting. The cutting has a high risk of cracking and poor reliability. Especially when the thickness of the wafer is relatively thin, the probability of cracking is higher. At the same time, the packaging efficiency of single chips is low, which is not conducive to mass supply.

[0004] Therefore, how to solve the above technical problems should be the focus of attention of those skilled in the art. SUMMARY

[0005] The purpose of the present application is to provide an ultrathin ultrasonic fingerprint chip and a packaging method thereof, so as to improve the problem of broken pieces and cracking when the chip is divided, and improve the packaging efficiency.

[0006] To solve the above technical problems, the present application provides a packaging method of an ultrathin ultrasonic fingerprint chip, comprising:

[0007] obtaining an array of ultrathin chips to be divided; the array of ultrathin chips to be divided comprises a wafer and a plurality of ultrathin ultrasonic fingerprint chip modules located on the upper surface of the wafer, each of the ultrathin ultrasonic fingerprint chip modules comprises an ultrasonic wave transmitting part, an ultrasonic wave receiving part, a polarization layer and an electrode;

[0008] a mask layer is made on the surface of the array of ultrathin chips to be divided, and the mask layer between adjacent ultrathin ultrasonic fingerprint chip modules is removed to form a division channel;

[0009] the wafer corresponding to the division channel is etched by a dry etching process, and the mask layer is removed to obtain a plurality of mutually separated ultrathin ultrasonic fingerprint chips.

[0010] Optionally, obtaining an array of ultrathin chips to be divided comprises:

[0011] the ultrasonic wave transmitting part and the ultrasonic wave receiving part are made on the upper surface of the wafer;

[0012] a first support plate is bonded on one side of the upper surface of the wafer;

[0013] thinning the wafer from a lower surface of the wafer under support of the first support plate;

[0014] bonding a second support plate to a lower surface of the thinned wafer;

[0015] removing the first support plate under support of the second support plate;

[0016] forming the polarization layer on a side of an upper surface of the wafer;

[0017] forming the electrode on the side of the upper surface of the wafer; the electrode is laminated on an upper surface of the polarization layer;

[0018] after etching the wafer corresponding to the segmentation channel by the dry etching process, the method further comprises:

[0019] removing the second support plate.

[0020] Optionally, the thinning the wafer from a lower surface of the wafer comprises:

[0021] thinning the wafer from the lower surface of the wafer by grinding.

[0022] Optionally, the forming the electrode on the side of the upper surface of the wafer comprises:

[0023] forming the electrode on the side of the upper surface of the wafer by electroplating.

[0024] Optionally, the method further comprises, before the forming the electrode on the side of the upper surface of the wafer:

[0025] forming a seed layer on the side of the upper surface of the wafer;

[0026] forming a patterned photoresist layer on an upper surface of the seed layer;

[0027] the forming the electrode on the side of the upper surface of the wafer comprises:

[0028] electroplating the electrode on the upper surface of the seed layer in regions not covered by the patterned photoresist layer;

[0029] removing the patterned photoresist layer;

[0030] removing the seed layer not covered by the electrode.

[0031] Optionally, the etching the wafer corresponding to the segmentation channel by the dry etching process comprises:

[0032] etching temperature is 20-40℃, etching pressure is 20-60mT, and biasing radio frequency power is 0-50W;

[0033] etching temperature is 20-40℃, etching pressure is 20-60mT, and biasing radio frequency power is 300-600W.

[0034] Optionally, before the surface of the array of to-be-divided ultra-thin chips is made with a mask layer, the method further comprises:

[0035] A protective layer is made on the upper surface of the electrode in each ultra-thin ultrasonic fingerprint chip module.

[0036] Optionally, the width of the division channel is less than or equal to 10 microns.

[0037] Optionally, the method further comprises:

[0038] A vacuum adsorption assembly is used to suck and remove the product generated in the dry etching process.

[0039] The application also provides an ultra-thin ultrasonic fingerprint chip obtained by using any one of the packaging methods of the ultra-thin ultrasonic fingerprint chip.

[0040] The packaging method of the ultra-thin ultrasonic fingerprint chip comprises: obtaining an array of to-be-divided ultra-thin chips; the array of to-be-divided ultra-thin chips comprises a wafer and a plurality of ultra-thin ultrasonic fingerprint chip modules on the upper surface of the wafer, each of the ultra-thin ultrasonic fingerprint chip modules comprises an ultrasonic wave transmitting part, an ultrasonic wave receiving part, a polarization layer and an electrode; a mask layer is made on the surface of the array of to-be-divided ultra-thin chips, and the mask layer between adjacent ultra-thin ultrasonic fingerprint chip modules is removed to form a division channel; a dry etching process is used to etch the wafer corresponding to the division channel, and the mask layer is removed to obtain a plurality of mutually separated ultra-thin ultrasonic fingerprint chips.

[0041] It can be seen that, in the packaging of the ultrathin ultrasonic fingerprint chip, the application obtains a to-be-segmented ultrathin chip array, then a mask layer is made on the surface of the to-be-segmented ultrathin chip array, and a segmentation channel is formed in the area between adjacent ultrathin ultrasonic fingerprint chip modules corresponding to the mask layer, so as to segment the wafer, and a dry etching process is used to etch part of the segmentation channel, so as to segment the wafer into multiple independent small blocks, and each small block wafer after segmentation and the ultrathin ultrasonic fingerprint chip module form an ultrathin ultrasonic fingerprint chip. The segmentation is performed by using the dry etching process, the segmentation is realized by means of chemical reaction, the risk of cracking caused by physical contact during cutter wheel cutting can be avoided, the reliability and packaging yield are improved, and in particular for packaging of the ultrathin ultrasonic fingerprint chip, when the wafer is very thin, the packaging yield can be further improved. In addition, in the application, multiple ultrathin ultrasonic fingerprint chip modules are formed on a wafer, and multiple ultrathin ultrasonic fingerprint chips can be obtained after segmentation, that is, multiple ultrathin ultrasonic chips are simultaneously packaged, and the packaging efficiency can be improved.

[0042] In addition, the application also provides an ultrathin ultrasonic fingerprint chip with the above advantages. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0044] Figure 1 The flow of the packaging method of the ultrathin ultrasonic fingerprint chip provided by the embodiment of the application Figure One ;

[0045] Figure 2 The flow of the packaging method of the ultrathin ultrasonic fingerprint chip provided by the embodiment of the application Figure Two ;

[0046] Figures 3 to 19 The packaging process flow chart of the ultrathin ultrasonic fingerprint chip provided by the embodiment of the application. DETAILED DESCRIPTION

[0047] In order to make the person skilled in the art better understand the application scheme, the application will be further described in detail below in combination with the drawings and specific embodiments. Obviously, the described embodiments are only some of the embodiments of the application, not all. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0048] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details set forth in this description, that the present application can be practiced with other systems, and that the present application can be practiced using different techniques. Therefore, the present application is not limited to the embodiments set forth in this description.

[0049] As described in the background section, the current ultrasonic fingerprint chip adopts a patch type package, and the separation of a single chip is cut by a cutter wheel, which has a high risk of cracking and poor reliability, and the packaging efficiency of a single chip is low, which is not conducive to batch supply.

[0050] Therefore, the present application provides a packaging method for an ultrathin ultrasonic fingerprint chip, as shown in Figure 1 The method can include:

[0051] Step S101: obtaining an array of ultrathin chips to be cut; the array of ultrathin chips to be cut includes a wafer and a plurality of ultrathin ultrasonic fingerprint chip modules located on the upper surface of the wafer, each of the ultrathin ultrasonic fingerprint chip modules includes an ultrasonic wave transmitting part, an ultrasonic wave receiving part, a polarization layer and an electrode.

[0052] In the present application, the ultrathin ultrasonic fingerprint chip refers to a chip with a wafer thickness of less than 100 microns.

[0053] The ultrathin ultrasonic fingerprint chip modules can be arranged in an array on the wafer. It should be noted that the number of ultrathin ultrasonic fingerprint chip modules on the wafer is not limited in the present application, but is determined according to the situation.

[0054] The ultrasonic wave transmitting part and the ultrasonic wave receiving part are located on the upper surface of the wafer; the polarization layer is located on the upper surface of the ultrasonic wave transmitting part and the ultrasonic wave receiving part, and can also be located on the upper surface and the side surface of the ultrasonic wave transmitting part and the ultrasonic wave receiving part, i.e. wrapping the ultrasonic wave transmitting part and the ultrasonic wave receiving part; the electrode is located on the upper surface of the polarization layer.

[0055] It should be noted that each ultrathin ultrasonic fingerprint chip module further includes an electrical connection part located on the upper surface of the wafer for connecting with an external circuit soft board for power supply.

[0056] Step S102: making a mask layer on the surface of the array of ultrathin chips to be cut, and removing the mask layer located between adjacent ultrathin ultrasonic fingerprint chip modules to form a cutting path.

[0057] The material of the mask layer can be photoresist, and the making method can be coating or film covering, etc., which is not limited in the present application.

[0058] The area where the cutting path is located can be regarded as a groove, and the lower part is the wafer.

[0059] It should be noted that the width of the segmentation channel is not limited in the present application and can be set by the user.

[0060] In an embodiment of the present application, the width of the segmentation channel is less than or equal to 10 microns.

[0061] Since the segmentation in the present application is performed by using a dry etching process, the opening requirement of the segmentation channel can be reduced, so that the width of the segmentation channel in the present application can be reduced to less than 10 microns, which is more conducive to the arrangement and utilization of chips on the wafer surface and improves the processing efficiency.

[0062] Step S103: etching the wafer corresponding to the segmentation channel by using a dry etching process and removing the mask layer to obtain a plurality of mutually separated ultrathin ultrasonic fingerprint chips.

[0063] The dry etching process can calculate the theoretical etching depth through the etching time, and the etching time can be controlled according to the thickness of the wafer to control the separation of the chips.

[0064] In the dry etching process, deposition is performed before each etching. Over-etching may occur at the bottom of the dry etching, which can be avoided by adjusting the gas content of C4F8 in the deposition stage, the gas content of SF6 in the first etching and second etching stages, the time and other parameters.

[0065] The dry etching process includes but is not limited to any one of reactive ion etching, plasma etching, and ion beam etching.

[0066] As an implementable manner, the etching of the wafer corresponding to the segmentation channel by using a dry etching process includes:

[0067] The wafer corresponding to the segmentation channel is etched by using a first dry etching process, wherein the etching gas includes C4F8 and SF6, the etching temperature is 20-40℃, the etching pressure is 20-60mT, and the bias radio frequency power is 0-50W.

[0068] The wafer corresponding to the segmentation channel is etched by using a second dry etching process, wherein the etching gas includes C4F8 and SF6, the etching temperature is 20-40℃, the etching pressure is 20-60mT, and the bias radio frequency power is 300-600W.

[0069] The flow rate of the gas in the first dry etching process and the second dry etching process is not limited in the present application and is determined according to the situation. For example, the flow rate of C4F8 can be 1sccm (Standard Cubic Centimeter per Minute), and the flow rate of SF6 can be 300sccm.

[0070] The duty cycle of the biasing radio frequency in the first dry etching process can be 5% to 25%, and the duty cycle of the biasing radio frequency in the second dry etching process can be 5% to 25%.

[0071] The etching process of the first dry etching process is a first etching stage, and the etching process of the second dry etching process is a second etching stage.

[0072] In the packaging of the ultrathin ultrasonic fingerprint chip, the array of the ultrathin chip to be segmented is obtained, then a mask layer is made on the surface of the array of the ultrathin chip to be segmented, and a segmentation channel is formed in the region between adjacent ultrathin ultrasonic fingerprint chip modules corresponding to the mask layer, so as to segment the wafer. A part in the segmentation channel is etched by using a dry etching process, so as to segment the wafer into multiple independent small blocks. Each small block of the segmented wafer and the ultrathin ultrasonic fingerprint chip module form an ultrathin ultrasonic fingerprint chip. The segmentation is performed by using the dry etching process, and the segmentation is realized by a chemical reaction. The risk of cracking caused by physical contact during cutter wheel cutting can be avoided, the reliability and packaging yield can be improved, the strength of the chip can be improved, and especially for the packaging of the ultrathin ultrasonic fingerprint chip, when the wafer is very thin, the packaging yield can be further improved. In addition, in the embodiment, multiple ultrathin ultrasonic fingerprint chip modules are formed on a wafer, and multiple ultrathin ultrasonic fingerprint chips can be obtained after segmentation, that is, multiple ultrathin ultrasonic chips are packaged at the same time, and the packaging efficiency can be improved. In addition, the application can also solve the problem of TTV (Total Thickness Variation) difference after chip packaging, and improve the uniformity of the chip.

[0073] Please refer to Figure 2 On the basis of the above-mentioned embodiments, in an embodiment of the present application, the packaging method of the ultrathin ultrasonic fingerprint chip comprises:

[0074] Step S201: making the ultrasonic wave transmitting part and the ultrasonic wave receiving part on the upper surface of the wafer.

[0075] The manufacturing process of this step is well known to those skilled in the art, and will not be described in detail here.

[0076] Step S202: bonding a first support plate on one side of the upper surface of the wafer.

[0077] The bonding connection layer is placed on the surface of the first support plate, and then the first support plate is placed on one side of the upper surface of the wafer, and the wafer is bonded by vacuum high-temperature pressing, so as to provide support for subsequent grinding. Alternatively, a bonding connection layer is made on one side of the upper surface of the wafer, and the bonding connection layer can be a bonding film or temporary bonding glue, etc. Then, the first support plate is placed on the bonding connection layer, and the bonding connection layer is made on one side of the upper surface of the wafer.

[0078] The first support plate can be a glass plate or other plate material, which is not limited in the present application.

[0079] Step S203: thinning the wafer from the lower surface of the wafer under the support of the first support plate.

[0080] It should be noted that the thinning method is not limited in the present application, as long as the wafer can be thinned.

[0081] As an implementation manner, the wafer is thinned from the lower surface of the wafer, including:

[0082] The wafer is thinned from the lower surface of the wafer by grinding.

[0083] The wafer is thinned by grinding, which has the characteristics of high efficiency and low cost, can improve the packaging efficiency and reduce the packaging cost.

[0084] In other embodiments, other thinning methods such as chemical mechanical polishing or wet etching can also be used to thin the wafer.

[0085] Due to the support of the first support plate, the thickness of the wafer can be thinned to 30-60 microns, and the specific thickness can be set according to the needs, for example, the thickness of the wafer can be 30 microns, 40 microns, 50 microns, 60 microns, etc. The thickness of the thinned wafer is very thin, which can further reduce the thickness and volume of the ultrathin ultrasonic fingerprint chip, and is more conducive to the application of the ultrathin ultrasonic fingerprint chip in ultrathin products such as mobile phones.

[0086] Step S204: bonding a second support plate to the lower surface of the thinned wafer.

[0087] The lower surface of the thinned wafer is cleaned to remove impurity particles adhering to the lower surface of the wafer during thinning. A bonding connection layer is placed on the second support plate, and then connected to the lower surface of the wafer through the bonding connection layer, and bonded to the wafer by vacuum high-temperature pressing. Alternatively, a bonding connection layer can be made on the lower surface of the thinned wafer, which can be a bonding film or temporary bonding glue, etc. Then place the second support plate on the bonding connection layer, and bond it to the wafer by vacuum high-temperature pressing.

[0088] The second support plate can provide support for the subsequent packaging process to solve the problem of breakage during production.

[0089] The second support plate can be a glass plate or other plate material, which is not limited in the present application.

[0090] Step S205: removing the first support plate under the support of the second support plate.

[0091] Step S206: making the polarization layer on the upper surface side of the wafer.

[0092] The making process of the polarization layer is well known to those skilled in the art, and will not be described in detail in this application.

[0093] After making the polarization layer, the electrical connection part area and the separation channel area should be exposed. The purpose of exposing the separation channel is to facilitate the dry etching groove in the later process and separate the chips. The electrical connection part area is exposed to ensure the power supply of the chip and the output exchange of the analysis result. The purpose of making the polarization layer is to realize the piezoelectric performance of the ultrathin ultrasonic fingerprint chip. The polarization layer has the advantages of chemical resistance, low acoustic impedance, corrosion resistance, high mechanical strength, and strong plasticity.

[0094] Step S207: making the electrode on the upper surface side of the wafer; the electrode is stacked on the upper surface of the polarization layer to obtain an array of ultrathin chips to be separated.

[0095] The material of the electrode can be a metal material, and the electrode includes but is not limited to any one or a combination of a tin layer, a nickel layer, a silver layer, a tin-silver layer, and a copper layer.

[0096] In order to solve the problem of wafer warping of the ultrathin chip silicon wafer, in an embodiment of the present application, the electrode can be any one or any combination of a tin layer, a nickel layer, and a tin-silver layer. The tin layer, the nickel layer, and the tin-silver layer can be used as compressive stress to reduce the wafer warping.

[0097] It should be noted that the making method of the electrode is not limited in the present application and can be selected as needed.

[0098] As an implementable manner, making the electrode on the upper surface side of the wafer includes:

[0099] The electrode is made on the upper surface side of the wafer by electroplating.

[0100] The electroplating method has the advantages of uniform plating layer, strong bonding force, high temperature corrosion resistance, etc., and provides additional physical properties to improve the conductivity and wear resistance.

[0101] In other embodiments of the present application, the electrode can also be made by evaporation or sputtering.

[0102] Step S208: making a mask layer on the surface of the array of ultrathin chips to be separated, and removing the mask layer between adjacent ultrathin ultrasonic fingerprint chip modules to form a separation channel.

[0103] Step S209: etching the wafer corresponding to the separation channel by a dry etching process, and removing the mask layer and the second support plate to obtain a plurality of mutually separated ultrathin ultrasonic fingerprint chips.

[0104] In the embodiment, the wafer thinning is performed before processing the wafer, compared with thinning the wafer after the polarizing layer and the electrode and other components are made on the wafer. In the embodiment, the wafer surface has no height difference of the packaging stack when the wafer is thinned, which can improve the uniformity of wafer thinning, solve the problem of poor grinding thickness uniformity, further reduce the overall thickness, improve the space utilization of the module, and realize technical improvement. Moreover, the thickness of the wafer can be thinned to be smaller in the application, which is more beneficial to the thinness of the ultrathin ultrasonic fingerprint chip, improves the space utilization of the terminal where the ultrathin ultrasonic fingerprint chip is located, and optimizes the assembly effect in the later stage.

[0105] On the basis of the above-mentioned embodiments, in an embodiment of the present application, when the electrode is made by electroplating, before the electrode is made on the upper surface side of the wafer, the method can further include:

[0106] Making a seed layer on the upper surface side of the wafer;

[0107] Making a patterned photoresist layer on the upper surface of the seed layer;

[0108] Making the electrode on the upper surface side of the wafer includes:

[0109] Electroplating the electrode on the region of the upper surface of the seed layer which is not covered by the patterned photoresist layer;

[0110] Removing the patterned photoresist layer;

[0111] Removing the seed layer which is not covered by the electrode.

[0112] The seed layer is located between the polarizing layer and the electrode. The seed layer serves to prepare for the subsequent electroplating of the metal layer to form the electrode, and can enhance the adhesion of the electrode and improve the quality of the electrode.

[0113] The seed layer can be a TiCu film layer or other film layer having the above-mentioned effects.

[0114] The seed layer can be made by sputtering or evaporation, which is not limited in the present application.

[0115] The seed layer which is not covered by the electrode is removed to prepare for the subsequent dry etching to separate single ultrathin ultrasonic fingerprint chips. When a protective layer is to be made, the seed layer can also be removed to prepare for the subsequent making of the protective layer. The seed layer can be removed by wet etching, and the etching solution can be selected according to the material of the seed layer.

[0116] On the basis of the above-mentioned embodiments, in an embodiment of the present application, before the mask layer is made on the surface of the wafer array to be divided, the method can further include:

[0117] A protective layer is formed on the upper surface of the electrode in each ultrathin ultrasonic fingerprint chip module.

[0118] The protective layer can protect the electrode from the erosion of the external environment, prolong the service life of the electroplated layer, and has excellent mechanical properties, excellent dimensional stability, low shrinkage, and can improve the warping and reliability of the ultrathin ultrasonic fingerprint chip.

[0119] The material of the protective layer includes but is not limited to photoresist or film materials, and the protective layer can be formed by spraying or spin coating, which is not limited in the present application.

[0120] On the basis of any of the above embodiments, in an embodiment of the present application, the packaging method of the ultrathin ultrasonic fingerprint chip can further include: using a vacuum adsorption assembly to suck and remove the product generated in the dry etching process.

[0121] In the present embodiment, the impurities such as particulate matter generated in the etching process are adsorbed and removed by using a vacuum adsorption assembly during the dry etching process, so that particulate pollution can be avoided.

[0122] In the present embodiment, the carbonization of the mask layer during the dry etching process can be avoided by using He (helium) for cooling during the dry etching process, or by dividing the etching into multiple etching stages and adjusting the duty cycle of the etching parameters in different etching stages to avoid the carbonization of the mask layer during the continuous etching. The etching parameters include any one or any combination of the duty cycle of the bias radio frequency, the bias radio frequency pulse frequency, the bias radio frequency peak power, the pulse synchronization timing, the etching chamber temperature, the etching gas flow, the pressure, etc.

[0123] In an embodiment of the present application, the packaging method of the ultrathin ultrasonic fingerprint chip after dry etching can further include:

[0124] The in-situ adhesive removal process is used to remove the polymer film on the side wall of the separation channel to avoid the accumulation of by-products.

[0125] The free radicals generated by the dissociation of the etching gas in the plasma are deposited on the side wall of the separation channel, but not completely volatilized. Such deposits are mainly composed of carbon (C), fluorine (F), hydrogen (H), and fragments of the etched wafer, forming a fluorocarbon polymer film.

[0126] The in-situ adhesive removal process can use a dry plasma ashing technique.

[0127] In this embodiment, an in-situ de-gluing process is adopted, that is, the removal of the mask layer is directly completed in the etching equipment, thereby reducing the risk of contaminating the chip and improving the process integration and efficiency.

[0128] On the basis of any of the above embodiments, in an embodiment of the present application, the packaging method of the ultrathin ultrasonic fingerprint chip can further include:

[0129] When the etching side wall angle is less than 90° in the dry etching process, any one or any combination of the following parameters is adjusted to adjust the etching angle: pressure, SRF (Source Radio Frequency, source radio frequency power), BRF (Bias Radio Frequency, bias radio frequency power), BRF Fre (Bias Radio Frequency Frequency, bias radio frequency frequency), and BRF duty (Bias Radio Frequency duty, bias radio frequency duty), so that the etching side wall angle is equal to 90°.

[0130] The packaging method in the present application will be described below in a specific case.

[0131] Step 1, please refer to Figure 3 An ultrasonic wave emitting part 2, an ultrasonic wave receiving part 3, and an electrical connection part 4 are made on the upper surface of the wafer 1.

[0132] Step 2, please refer to Figure 4 A temporary bonding process is performed on one side of the upper surface of the wafer 1, a bonding connection layer 6 is made on the first support plate 5, and then the wafer 1 is bonded to the upper surface of the wafer 1 by vacuum high-temperature compression bonding.

[0133] Step 3, please refer to Figure 5 The wafer 1 after the temporary bonding is thinned by grinding.

[0134] Step 4, please refer to Figures 6 to 7 The surface (lower surface) after thinning is cleaned, a bonding connection layer 6 is made on the second support plate 7, and then the wafer 1 is bonded to the lower surface of the wafer 1 by vacuum high-temperature compression bonding to complete the temporary bonding on the lower surface, and the first support plate 5 and the bonding connection layer 6 on the upper surface of the wafer 1 are disassembled.

[0135] Step 5, please refer to Figure 8 A polarization layer 8 is made on the upper surface of the wafer 1, and the electrical connection part 4 and the division channel 9 region are exposed.

[0136] Step 6, please refer to Figure 9 A seed layer 10 is made on the entire surface of one side of the upper surface of the wafer 1.

[0137] Step 7, please refer to Figure 10 A patterned photoresist 11 is made on the upper surface of the seed layer 10, and the area of the seed layer 10 not covered by the photoresist is the area for making the electrode 12 later;

[0138] Step 8, please refer to Figure 11 A metal layer is made on the upper surface of the seed layer 10 by electroplating process to form the electrode 12;

[0139] Step 9, please refer to Figures 12 to 13 The patterned photoresist 11 on the upper surface of the seed layer 10 is removed, and then the exposed seed layer 10 is removed by wet etching, to prepare for the separation of the protection layer 13 and the single ultra-thin ultrasonic fingerprint chip later;

[0140] Step 10, please refer to Figure 14 The protection layer 13 is made on the upper surface of the electrode 12, and the protection layer 13 can completely wrap the electrode 12;

[0141] Step 11, please refer to Figure 15 The photoresist 14 is coated on one side of the upper surface of the wafer 1, and the separation channel 9 area is exposed;

[0142] Step 12, please refer to Figure 16 The dry etching process is used to remove the wafer 1 in the separation channel 9 area not covered by the photoresist 14 by etching a straight groove, and the etching is stopped at the second support plate 7, to complete the separation of the single ultra-thin ultrasonic fingerprint chip;

[0143] Step 13, please refer to Figures 17 to 18 The photoresist 14 on one side of the upper surface of the wafer 1 is removed, and the second support plate 7 is removed, to obtain a single ultra-thin ultrasonic fingerprint chip 100, and the packaging is completed, as shown in Figure 19

[0144] The application also provides an ultra-thin ultrasonic fingerprint chip obtained by the packaging method of the ultra-thin ultrasonic fingerprint chip according to any one of the embodiments.

[0145] In the present specification, each embodiment is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts of each embodiment can be referred to each other.

[0146] ​The above describes in detail the ultrathin ultrasonic fingerprint chip and the packaging method thereof provided by the present application. The principles and implementation manners of the present application are described by using specific examples, and the above description of the examples is only used to help understand the scheme of the present application and the core idea thereof. It should be pointed out that, for those skilled in the art, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the present application.

Claims

1. A packaging method of an ultrathin ultrasonic fingerprint chip, characterized in that, include: obtaining an array of ultra-thin chips to be segmented; The ultra-thin chip array to be divided includes a wafer and a plurality of ultra-thin ultrasonic fingerprint chip modules located on the upper surface of the wafer, each of the ultra-thin ultrasonic fingerprint chip modules includes an ultrasonic transmitter, an ultrasonic receiver, a polarization layer and an electrode; Making a mask layer on the surface of the ultra-thin chip array to be segmented, and removing the mask layer between adjacent ultra-thin ultrasonic fingerprint chip modules to form segmentation lanes; The wafer corresponding to the dividing streets is etched using a dry etching process, and the mask layer is removed to obtain a plurality of ultra-thin ultrasonic fingerprint chips separated from each other.

2. The packaging method of the ultrathin ultrasonic fingerprint chip according to claim 1, wherein, Obtaining an array of ultra-thin chips to be segmented includes: Fabricating the ultrasonic transmitting portion and the ultrasonic receiving portion on the upper surface of the wafer; bonding a first support plate to one side of the upper surface of the wafer; thinning the wafer from the lower surface of the wafer under the support of the first support plate; bonding a second support plate to the lower surface of the thinned wafer; Under the support of the second support plate, removing the first support plate; forming the polarization layer on one side of the upper surface of the wafer; The electrode is fabricated on one side of the upper surface of the wafer; the electrode is stacked on the upper surface of the polarization layer; After etching the wafer corresponding to the dividing streets using a dry etching process, the method further includes: Remove the second support plate.

3. The packaging method of the ultrathin ultrasonic fingerprint chip according to claim 2, wherein, Thinning the wafer from a lower surface of the wafer includes: The wafer is thinned from the lower surface of the wafer by grinding.

4. The packaging method of the ultrathin ultrasonic fingerprint chip according to claim 2, wherein, Producing the electrode on one side of the upper surface of the wafer includes: The electrode is manufactured on one side of the upper surface of the wafer by electroplating.

5. The packaging method of the ultrathin ultrasonic fingerprint chip according to claim 4, wherein, Before forming the electrode on the upper surface of the wafer, the method further includes: forming a seed layer on one side of the upper surface of the wafer; forming a patterned photoresist layer on the upper surface of the seed layer; Producing the electrode on one side of the upper surface of the wafer includes: electroplating the electrode in an area of ​​the upper surface of the seed layer not covered by the patterned photoresist layer; removing the patterned photoresist layer; The seed layer not covered by the electrode is removed.

6. The packaging method of the ultrathin ultrasonic fingerprint chip according to claim 1, wherein, Etching the wafer corresponding to the dividing street using a dry etching process includes: Etching the wafer corresponding to the dividing street using a first dry etching process, wherein the etching gas includes C4F8 and SF6, the etching temperature is 20° C. to 40° C., the etching pressure is 20 to 60 mT, and the bias RF power is 0 to 50 W; The wafer corresponding to the dividing street is etched using a second dry etching process, wherein the etching gas includes C4F8 and SF6, the etching temperature is 20°C to 40°C, the etching pressure is 20 to 60mT, and the bias RF power is 300 to 600W.

7. The packaging method of the ultrathin ultrasonic fingerprint chip according to claim 1, wherein, Before forming a mask layer on the surface of the ultra-thin chip array to be divided, the method further comprises: A protective layer is formed on the upper surface of the electrode in each ultra-thin ultrasonic fingerprint chip module.

8. The packaging method of the ultrathin ultrasonic fingerprint chip according to claim 1, wherein, The width of the dividing street is less than or equal to 10 micrometers.

9. The packaging method of an ultrathin ultrasonic fingerprint chip according to any one of claims 1 to 8, characterized in that, Also includes: The products generated in the dry etching process are sucked away using a vacuum adsorption component.

10. An ultrathin ultrasonic fingerprint chip, characterized in that, The ultra-thin ultrasonic fingerprint chip is obtained by adopting the packaging method of any one of claims 1 to 9.

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