Image sensor processing method and analysis method

Abstract

The application discloses an image sensor processing method and an analysis method. In the image sensor processing method, the image sensor comprises a filter, a DAF film, a bare chip and a packaging substrate arranged in sequence. The method comprises the following steps: etching a corrosion groove on the packaging material between the filter and the wire of the image sensor sample; adding acid liquid into the corrosion groove to expose the DAF film; baking the sample after corrosion to obtain a sample after baking; heating the position of the filter in the sample after baking until the DAF film in contact with the filter is cracked, the filter is separated, and a sample after removing the filter is obtained; and removing the DAF film on the surface of the bare chip in the sample after removing the filter to obtain an assembly with the surface of the bare chip exposed. The image sensor processing method can expose the surface of the bare chip, and meanwhile, does not cause damage to the bare chip, so that subsequent analysis and test such as failure analysis and hot spot analysis on the bare chip can be carried out.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chip testing, in particular to an image sensor processing method and an analysis method. BACKGROUND

[0002] As a key electronic device for converting optical images into electrical signals, image sensors have a wide range of applications in digital cameras, smart phones, security monitoring, medical imaging, and autonomous driving. As the core component of modern imaging systems, its performance directly determines the key indicators such as image clarity, color restoration ability, and dynamic range. With the rapid development of technology, the demand for image sensor chips in intelligent vehicles, robots, and unmanned aerial vehicles has increased significantly, and the frequency of use has also increased significantly, which has led to a frequent occurrence of various image sensor failures. When analyzing the failure of image sensor chips, the filter attached to the packaging surface often hinders hot spot analysis and visual inspection, which poses a significant challenge to failure analysis. However, at present, there is no perfect method for removing the filter on the packaging surface of the image sensor without damaging the chip.

[0003] In view of this, the present application is proposed. SUMMARY

[0004] The purpose of the present application is to provide an image sensor processing method and an analysis method to reduce damage to the die during the process of peeling off the filter and the DAF film in the image sensor.

[0005] The present application is implemented as follows:

[0006] In a first aspect, the present application provides an image sensor processing method, the image sensor comprising a filter, a DAF film, a die, and a packaging substrate arranged in sequence, and the method comprising:

[0007] Slotting: a corrosion slot is formed on the packaging material between the filter and the wire bonding of the image sensor sample;

[0008] Acid etching: acid is added to the corrosion slot to etch and clean the packaging material, exposing the DAF film, and obtaining an etched sample;

[0009] Baking: the etched sample is baked to obtain a baked sample;

[0010] Filter peeling: the position of the filter in the baked sample is heated until the DAF film in contact with the filter cracks, and the filter is separated, obtaining a sample without the filter;

[0011] DAF film removal: the DAF film on the surface of the die in the sample without the filter is removed, obtaining a component with the die surface exposed.

[0012] In an optional embodiment, the baking temperature is 115-125°C, and the baking time is 3.5-4.5h.

[0013] In an optional embodiment, the distance between the etching groove and the filter is greater than a preset value.

[0014] In an optional embodiment, before the slotting step, the distance between the filter and the wire and the thickness of the packaging material in the image sensor sample are observed by X-ray, and the laser is avoided from damaging the die during slotting.

[0015] In an optional embodiment, the etching groove is formed on at least one side of the filter.

[0016] In an optional embodiment, the acid solution comprises at least one of fuming nitric acid and concentrated sulfuric acid.

[0017] In an optional embodiment, the etching step is repeated more than twice, the etching temperature is 95-105°C, and the etching time is 4-6s each time.

[0018] In an optional embodiment, the cleaning agent used in the cleaning step is at least one of acetone and alcohol.

[0019] In an optional embodiment, each etching corresponds to a cleaning step.

[0020] In an optional embodiment, the etched sample is dried before baking.

[0021] In an optional embodiment, the heating temperature in the heating step is 300-350°C.

[0022] In an optional embodiment, the filter is uniformly heated at each position in the heating step by using a heat source.

[0023] In an optional embodiment, the DAF film removing step comprises: immersing the sample after removing the filter in a solvent, then peeling off the DAF film on the surface of the die to obtain a component with the die surface exposed.

[0024] In an optional embodiment, the solvent is acetone.

[0025] In an optional embodiment, the immersion time is 25-35min.

[0026] In a second aspect, the present application provides a method for analyzing a die, comprising:

[0027] Analyzing the component with the die surface exposed obtained in the image sensor processing method according to any one of the preceding embodiments.

[0028] In an optional embodiment, the image sensor sequentially comprises a filter, a DAF film, a die A, a DAF film, a die B and a packaging substrate from top to bottom; the surface of the die A is exposed by using the image sensor processing method, and the die A is analyzed; after the analysis of the die A is completed, the DAF film on the surface of the die A and the die B is peeled off to expose the surface of the die B, and then the die B is analyzed.

[0029] The present application has the following beneficial effects:

[0030] The image sensor processing method in the present application can expose the surface of the die without damaging the die, so as to facilitate subsequent analysis and testing of the die, such as failure analysis and hot spot analysis. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0032] Figure 1 The flowchart of the image sensor processing method in the present application;

[0033] Figure 2 The appearance of the image sensor sample in Example 1;

[0034] Figure 3 The structural schematic diagram of one perspective of the image sensor sample in Example 1;

[0035] Figure 4 The position schematic diagram of the etching groove of the image sensor sample in Example 1;

[0036] Figure 5 The appearance of the component with the surface of the die exposed in Example 1;

[0037] Figure 6 The position schematic diagram of the etching groove of the image sensor sample in Example 3.

[0038] Illustration: 1-filter; 2-DAF film; 3-die A; 5-die B; 6-packaging substrate; 7-wire; 8-etching groove. DETAILED DESCRIPTION

[0039] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. If specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturers are adopted. If the manufacturers of the reagents or instruments are not specified, the conventional products that can be purchased in the market are adopted.

[0040] In order to avoid the influence of the filter on the image sensor die, some studies directly add acid to corrode the outer package of the image sensor to obtain the internal die. However, because the filter on the surface of the image sensor die is usually closely attached to the surface of the internal die by using a DAF (Die Attach Film, that is, a chip sticking film) or a colloid, the acid corrosion process takes a long time, and it is difficult to strip the DAF film covered by the filter, which increases the risk of damage to the die during stripping of the filter and the DAF film. Therefore, in some cases where the die is required to be complete and only the top filter and the DAF film are removed for analysis and inspection, the aforementioned method of directly adding acid to corrode the outer package of the image sensor to obtain the internal die is obviously no longer applicable. In order to improve the efficiency and accuracy of image sensor analysis and reduce the damage to the die caused during the process of stripping the filter and the DAF film on the image sensor die, the embodiments of the present application provide the following method:

[0041] An image sensor processing method, the image sensor comprising a filter, a DAF film, a die and a packaging substrate arranged in sequence, as shown in Figure 1 The method comprises:

[0042] Slotting, a corrosion slot is formed on the packaging material between the filter and the wire bonding of the image sensor sample;

[0043] Acid corrosion, acid is added to the corrosion slot to corrode and clean the packaging material, so that the DAF film is exposed, and a corroded sample is obtained;

[0044] Baking, baking the corroded sample to obtain a baked sample;

[0045] Filter stripping, heating the position of the filter in the baked sample until the DAF film in contact with the filter cracks, separating the filter, and obtaining a sample after removing the filter;

[0046] DAF film removal, removing the DAF film on the surface of the die in the sample after removing the filter, and obtaining a component with the surface of the die exposed.

[0047] The image sensor processing method in the present application is suitable for removing the optical filter and the DAF film on the surface of the die. In some embodiments, the image sensor can include two or more dies (i.e. Die below), and the DAF film and the optical filter on the uppermost die can be removed first by the method in the present application, so that the surface of the uppermost die close to the optical filter is exposed for subsequent analysis. For other dies far away from the optical filter, if analysis is needed, other methods can be used. Therefore, the die in the present application refers to the die bonded with the DAF film and the optical filter unless otherwise specified.

[0048] In some embodiments, the image sensor has two dies, e.g. Die A and Die B, and the image sensor includes, from top to bottom, the optical filter, the DAF film, Die A (i.e. Die A), the DAF film, Die B (i.e. Die B), and the packaging substrate, and the edge of the optical filter and the packaging substrate are encapsulated by the encapsulation material. After the image sensor is processed by the image sensor processing method in the present application, the components exposed on the surface of the die include, from top to bottom, Die A, the DAF film, Die B, and the packaging substrate, wherein the upper surface of Die A is exposed for subsequent analysis and test of Die A, such as failure analysis and hot spot analysis.

[0049] In other embodiments, the image sensor has only one die, and the image sensor includes, from top to bottom, the optical filter, the DAF film, the die, and the packaging substrate, and the edge of the optical filter and the packaging substrate are encapsulated by the encapsulation material. After the image sensor is processed by the image sensor processing method in the present application, the components exposed on the surface of the die include the die and the packaging substrate, and subsequent analysis and test of the die, such as failure analysis and hot spot analysis, can be performed.

[0050] The image sensor processing method in the present application can expose the surface of the die without damaging the die.

[0051] In optional embodiments, the baking temperature is 115-125°C, and the baking time is 3.5-4.5h.

[0052] The main purpose of the baking in the present application is to remove the residual detergent and water vapor in the sample after etching. In optional embodiments, the baking temperature can be 115-125°C, specifically 115°C, 117°C, 119°C, 121°C, 123°C, 125°C or any value between 115-125°C. Appropriately increasing the temperature is conducive to the rapid evaporation of the detergent and water vapor, so as to improve the efficiency, but too high temperature may cause the die damage due to the too violent gasification of the detergent and water vapor. In optional embodiments, the baking time is 3.5-4.5h, specifically 3.5h, 3.7h, 3.9h, 4.1h, 4.3h, 4.5h or any value between 3.5-4.5h, compared with the conventional unpacking of the die without filter, the longer baking time in the present application is needed to reduce the damage of the die in the subsequent filter peeling step.

[0053] In optional embodiments, the distance between the etching groove and the filter should not be too small to avoid the etching groove being too close to the filter, which may cause damage to the die under the filter during the slotting process. The distance between the etching groove and the filter can be greater than a preset value, for example, the preset value can be 50um. In some embodiments, the slotting can use laser irradiation.

[0054] In optional embodiments, before the slotting step, the distance between the filter and the wire bonding and the thickness of the packaging material in the image sensor sample are observed by X-ray, and the laser damage to the die is avoided during the slotting.

[0055] By observing the distance between the filter and the wire bonding and the thickness of the packaging material in the image sensor sample by X-ray, the etching groove depth can be preliminarily estimated to avoid the die side damage in the subsequent step due to the etching groove being too deep, which affects the analysis of the subsequent die.

[0056] In optional embodiments, the etching groove is arranged on at least one side of the filter. In some embodiments, the etching groove can be arranged on one side of the die, or on any two sides, any three sides or four sides of the filter, and the number of etching grooves can be one, two or even more. Specifically, in some embodiments, the etching groove can be arranged along one side of the filter; in other embodiments, a "L" shaped etching groove can be arranged along three sides of the filter; and in still other embodiments, a linear etching groove can be arranged around four sides of the filter. It should be noted that no matter how many etching grooves are arranged and how the etching grooves are shaped, the distance between the etching groove and the filter should be kept at a preset value to avoid laser damage to the die during the slotting, and the preset distance can be determined according to the distance between the filter and the wire bonding and the thickness of the packaging material in the image sensor sample observed by X-ray.

[0057] In optional embodiments, the acid solution comprises at least one of fuming nitric acid and concentrated sulfuric acid, and specifically, the acid solution can be fuming nitric acid, or concentrated sulfuric acid, or a mixed acid of fuming nitric acid and concentrated sulfuric acid, as long as the corrosion of the packaging material can be achieved.

[0058] In optional embodiments, the corrosion step is repeated more than twice, the corrosion temperature is 95-105°C, and the corrosion time is 4-6 seconds each time.

[0059] Specifically, the corrosion temperature can be 95°C, 97°C, 99°C, 101°C, 103°C, 105°C, or any value between 95°C and 105°C, and appropriately increasing the corrosion temperature can accelerate the corrosion rate, which is conducive to improving the efficiency, but if the corrosion temperature is too high, the corrosion rate will be too fast, which may cause excessive corrosion and damage to the die. The corrosion time can be 4 seconds, 4.5 seconds, 5 seconds, 5.5 seconds, 6 seconds, or any value between 4 seconds and 6 seconds, and in order to avoid excessive corrosion, multiple short-time corrosion can be performed, and after each corrosion is completed, it is observed whether the DAF film is exposed, and if the single corrosion time is too long, the die may be directly corroded, causing damage to the die. If the single corrosion time is too short, it will also lead to frequent stopping of the corrosion reaction, resulting in reduced efficiency. In optional embodiments, the washing agent used in the cleaning step is selected from at least one of acetone and alcohol, and specifically, the washing agent can be acetone, or alcohol, or a mixture of acetone and alcohol, and the acid solution in the acid corrosion process is washed away with the washing agent to stop the corrosion reaction.

[0060] In optional embodiments, each corrosion corresponds to a cleaning step to stop the corrosion reaction. Therefore, if the single corrosion time is too short, the cleaning step will be increased, which will cause waste of the washing agent, increase the cost, and reduce the efficiency.

[0061] In optional embodiments, the sample after corrosion is dried before baking. Drying the sample after corrosion can remove most of the washing agent and moisture in the sample after corrosion, which can reduce the change in internal pressure of the sample after corrosion caused by the gasification of the washing agent and moisture during baking, and avoid damage to the die caused by excessive internal pressure of the sample after corrosion during the baking process.

[0062] In optional embodiments, the heating temperature of the heating step is 300-350°C, and specifically, the heating temperature can be 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, or any value between 300°C and 350°C. The purpose of the heating step is to accelerate the deterioration of the DAF film and remove the stickiness of the DAF film, so as to peel off the filter. Therefore, appropriately increasing the heating temperature is conducive to improving the efficiency, but if the heating temperature is too high, it may cause damage to the die, so the heating temperature needs to be reasonably selected.

[0063] In optional embodiments, the heating step uses a heat source to uniformly heat the filter at each position, so that the DAF film uniformly cracks at each position. If the DAF film in some areas still has a relatively large adhesion after cracking during the filter peeling process, the peeling difficulty of the filter will increase, and the risk of damage to the die will also greatly increase. In some embodiments, a heat source is used to heat around the edge of the filter, and then the radius of the circle is gradually reduced until the filter is uniformly heated at each position, and the corresponding DAF film at each position of the filter cracks relatively uniformly, and the heating is stopped.

[0064] In some embodiments, when the DAF film cracks, a scalpel or a structure similar to a scalpel can be used to gently lift up from the bonding position between the DAF and the filter to remove the filter.

[0065] In optional embodiments, the DAF film step includes: placing the sample after the filter is removed in a solvent for soaking, and then peeling the DAF film on the surface of the die to obtain a component exposed on the surface of the die.

[0066] During the soaking process, the DAF film dissolves and swells, and the adhesion between the DAF film and the die becomes weak. At this time, a slight force can be used to peel the residual DAF film from the surface of the die. In some embodiments, a cotton swab or a similar cotton swab with a relatively soft material can be used to gently wipe the surface of the die to avoid scratches or cracks on the surface of the die caused by excessive force or hard wiping material during the process of removing the residual DAF film.

[0067] In optional embodiments, the solvent is selected from acetone to dissolve or swell the DAF film. In some embodiments, the solvent can also be heated appropriately to improve efficiency. However, it should be noted that acetone itself has strong volatility, so it is recommended to perform the soaking process in a sealed container or a fume hood to avoid injury to the operator.

[0068] In optional embodiments, the soaking time is 25-35 min, and specifically can be 25-35 min or any value between 25-35 min. Appropriately extending the soaking time is beneficial to weakening the adhesion between the DAF film and the die. If the adhesion between the DAF film and the die is weakened and the soaking is continued, only the efficiency will be reduced.

[0069] The embodiments of the present application also provide an image sensor analysis method, comprising:

[0070] The component exposed on the surface of the die obtained by the image sensor processing method of any one of the foregoing embodiments is analyzed.

[0071] The analysis includes failure analysis and hot spot analysis, etc. The failure analysis aims to determine the physical and electrical reasons for the failure of the die, and the hot spot analysis is specially used for locating the local high temperature area inside the die caused by defects (such as short circuit, leakage), and the combination of the two can more effectively evaluate the failure reasons of the image sensor.

[0072] In an optional embodiment, the image sensor sequentially comprises a filter, a DAF film, a die A, a DAF film, a die B and a packaging substrate from top to bottom; the surface of the die A is exposed by using the image sensor processing method, and then the die A is analyzed; after the analysis of the die A is completed, the DAF film on the surface of the die A and the die B is peeled off to expose the surface of the die B, and then the die B is analyzed.

[0073] When the image sensor includes two or more dies, whether to analyze the die B can be selected according to the analysis result of the die A; in some cases, in order to obtain more reliable analysis results, the die B can also be analyzed regardless of the analysis result of the die A.

[0074] The features and performances of the present application are further described in detail below in combination with embodiments.

[0075] Embodiment 1

[0076] The present embodiment provides an image sensor processing method, which specifically comprises the following steps:

[0077] Step one: sample observation and measurement;

[0078] First, the internal structure of the image sensor sample is observed by using X-ray, and the distance from the filter to the wire and the thickness of the packaging material are measured. The appearance of the image sensor sample is shown in Figure 2 , and the structure of the image sensor sample is shown in Figure 3 . The image sensor sample sequentially comprises a filter 1, a DAF film 2, a die A 3, a DAF film 2, a die B 5 and a packaging substrate 6 from top to bottom, and the filter 1 edge and the packaging substrate 6 are packaged by using a packaging material, and the die A 3 and the die B 5 are connected with the packaging substrate 6 through a wire 7.

[0079] Step two: slotting;

[0080] According to the results of X-ray observation and measurement in step one, a corrosion slot 8 is formed on the packaging material between the filter 1 and the wire 7 by using a laser, so as to avoid laser damage to the lower layer die A 3 when the laser is transmitted through the filter 1.

[0081] The slotting position is shown in Figure 4As shown, the etching groove 8 is arranged at one side of the optical filter 1, and the shortest distance between the etching groove 8 and the optical filter 1 is 50 um.

[0082] Step three: acid etching;

[0083] The mixed acid of fuming nitric acid and concentrated sulfuric acid with a mass ratio of 1:1 is dropped into the etching groove 8, and the image sensor sample is placed on a heating furnace at 100°C for heating for 5s, and then washed with acetone.

[0084] The above dropping and washing steps are repeated for 8 times to expose the DAF film 2 to obtain an etched sample. The repeated dropping and washing steps can ensure that the packaging material is not excessively etched, and the etching is stopped when the DAF layer between the optical filter 1 and the Die A 3 is exposed.

[0085] Step four: baking;

[0086] After the etched sample is dried, it is placed in an oven at 120°C for 4h to evaporate and remove the water vapor and washing agent introduced in the process, thereby obtaining a baked sample.

[0087] Step five, removing the optical filter 1;

[0088] The baked sample is placed in a clamp and placed under a microscope for uniform heating of the position of the optical filter 1 to 320°C. When the DAF film 2 is cracked due to high temperature, a scalpel is used to gently lift the optical filter 1 from the bonding position of the DAF and the optical filter, thereby obtaining a sample without the optical filter 1.

[0089] Step six, the sample without the optical filter 1 is placed in acetone for half an hour, and then the DAF film 2 on the surface of the Die A 3 is wiped off with a cotton swab, thereby obtaining a component with the surface of the Die A exposed, as shown in Figure 5 .

[0090] Step seven, the surface of the Die A is checked for abnormalities such as damage, scratches, and burns using an optical microscope. If there is no abnormality, the Die A 3 is subjected to subsequent failure analysis and hot spot analysis.

[0091] Example 2

[0092] The embodiment provides an image sensor processing method, which specifically includes the following steps:

[0093] Step one: sample observation and measurement;

[0094] First, the internal structure of the image sensor sample is observed by X-ray, and the distance from the filter 1 to the wire 7 and the thickness of the packaging material are measured. The image sensor sample includes the filter 1, the DAF film 2, the Die, and the packaging substrate 6 from top to bottom, and the filter 1 edge and the packaging substrate 6 are packaged by the packaging material, and the Die is connected to the packaging substrate 6 by the wire 7.

[0095] Step two: slotting;

[0096] According to the measurement results of the X-ray observation in step one, a corrosion slot 8 is opened on the packaging material between the filter 1 and the wire 7 by Laser, so as to avoid laser damage to the lower layer Die when Laser.

[0097] The slotting position is as shown in Figure 4 The corrosion slot 8 is arranged at one side of the filter 1, and the shortest distance from the corrosion slot 8 to the filter 1 is 60 um.

[0098] Step three: acid corrosion;

[0099] Fuming nitric acid is dropped in the corrosion slot 8, and the image sensor sample is placed in a heating furnace at 95°C for heating for 6s, and then washed with a mixed solution of acetone and alcohol with a mass ratio of 1:1.

[0100] The above dropping and washing steps are repeated for 9 times to expose the DAF film 2, and a corroded sample is obtained; the dropping and washing steps are repeated to ensure that the packaging material is not excessively corroded, and the corrosion is stopped when the DAF layer between the filter 1 and the Die is exposed.

[0101] Step four: baking;

[0102] After the corroded sample is dried, it is placed in an oven at 115°C for 6h, so that the water vapor and washing agent introduced in the process are evaporated and removed, and a baked sample is obtained.

[0103] Step five, remove the filter 1;

[0104] The baked sample is placed in a clamp, and the position of the filter 1 is uniformly heated to 300°C under a microscope, and when the DAF film 2 is slightly cracked due to high temperature, a scalpel is used to gently lift up from the bonding position of the DAF and the filter, and the filter 1 is removed, and a sample without the filter 1 is obtained.

[0105] Step six, the sample without the filter 1 is placed in acetone for 35min, and the DAF film 2 on the surface of the Die is wiped off with a cotton swab.

[0106] Step seven. Check the Die surface for abnormalities, such as damage, scratches, burns, etc. using an optical microscope. If there are no abnormalities, proceed to subsequent failure analysis and hot spot analysis.

[0107] Example 3

[0108] The embodiment provides an image sensor processing method, and specifically comprises the following steps:

[0109] Step one: sample observation and measurement;

[0110] First, the internal structure of the image sensor sample is observed using X-ray, and the distance from the optical filter 1 to the wire 7 and the thickness of the packaging material are measured. As shown in the structure of the image sensor sample, Figure 3 from top to bottom, the image sensor sample comprises the optical filter 1, the DAF film 2, the Die A 3, the DAF film 2, the Die B 5 and the packaging substrate 6, and the optical filter 1 edge and the packaging substrate 6 are packaged by the packaging material, and the Die A 3 and the Die B 5 are connected to the packaging substrate 6 through the wire 7.

[0111] Step two: slotting;

[0112] According to the results of the X-ray observation and measurement in step one, a corrosion slot 8 is formed on the packaging material between the optical filter 1 and the wire 7 by using a laser, so as to avoid laser damage to the lower layer Die A 3 when the laser is transmitted through the optical filter 1.

[0113] The slotting position is as shown in the figure, Figure 6 the corrosion slot 8 is arranged in a “mouth” shape around the optical filter 1, and the shortest distance between the corrosion slot 8 and the optical filter 1 is 50 um.

[0114] Step three: acid corrosion;

[0115] Concentrated sulfuric acid is dropped into the corrosion slot 8, and the image sensor sample is placed in a heating furnace at 105℃ for 4s, and then washed with alcohol.

[0116] The above-mentioned dropping of mixed acid and washing steps are repeated for 8 times, so as to expose the DAF film 2, and obtain a corroded sample; the dropping of mixed acid and washing steps can ensure that the packaging material is not excessively corroded, and the corrosion is stopped when the DAF layer between the optical filter 1 and the Die A 3 is exposed.

[0117] Step four: baking;

[0118] After the corroded sample is dried, it is placed in an oven at 125℃ for 3h, so that the water vapor and washing agent introduced in the processing process are evaporated and removed, and a baked sample is obtained.

[0119] Step five, remove the optical filter 1;

[0120] Put the baked sample into the clamp, and place it under the microscope to uniformly heat the position where the filter 1 is located to 350°C. When the DAF film 2 is slightly cracked due to high temperature, gently lift the DAF film 2 from the bonding position between the DAF and the filter using a scalpel, remove the filter 1, and obtain the sample after removing the filter 1.

[0121] Step six, immerse the sample after removing the filter 1 in acetone for 25 min, and then wipe the DAF film 2 on the surface of the Die A 3 with a cotton swab.

[0122] Step seven, use an optical microscope to check whether there is any abnormality, such as damage, scratch, burn, etc., on the surface of the Die A. If there is no abnormality, proceed with subsequent failure analysis and hot spot analysis.

[0123] Example 4

[0124] The embodiment provides an image sensor processing method, and the main difference from the embodiment 1 is that the baking time is shortened, and specifically includes the following steps:

[0125] Step one: sample observation and measurement;

[0126] First, use X-ray to observe the internal structure of the image sensor sample, measure the distance from the filter 1 to the wire 7, and measure the thickness of the packaging material. As shown in the structure of the image sensor sample, Figure 3 the image sensor sample includes, from top to bottom, the filter 1, the DAF film 2, the Die A 3, the DAF film 2, the Die B 5, and the packaging substrate 6, and the filter 1 edge and the packaging substrate 6 are packaged with the packaging material, and the Die A 3 and the Die B 5 are connected to the packaging substrate 6 through the wire 7.

[0127] Step two: slotting;

[0128] According to the results of X-ray observation and measurement in step one, a corrosion slot 8 is formed on the packaging material between the filter 1 and the wire 7 by using a laser, so as to avoid damage to the lower layer Die A 3 when the laser transmits through the filter 1.

[0129] The slotting position is as shown in the structure of the image sensor sample, Figure 4 the corrosion slot 8 is arranged on one side of the filter 1, and the shortest distance between the corrosion slot 8 and the filter 1 is 50 um.

[0130] Step three: acid etching;

[0131] A mixed acid of fuming nitric acid and concentrated sulfuric acid with a mass ratio of 1:1 is dropped into the corrosion slot 8, and the image sensor sample is placed on a heating furnace at 100°C for 5s, and then washed with acetone.

[0132] The above-mentioned drop-mixing acid and flushing steps are repeated 8 times to expose the DAF film 2 to obtain a post-etching sample; the repeated drop-mixing acid and flushing steps can ensure that the packaging material is not excessively etched, and the etching is stopped when the DAF layer between the optical filter 1 and the Die A 3 is exposed.

[0133] Step four: baking;

[0134] After the post-etching sample is dried, it is placed in an oven at 120°C for 2 hours to evaporate and remove the water vapor and washing agent introduced during the process, thereby obtaining a post-baking sample.

[0135] Step five: removing the optical filter 1;

[0136] The post-baking sample is placed in a clamp and subjected to uniform heating to 320°C under a microscope at the position of the optical filter 1. When the DAF film 2 is slightly cracked due to high temperature, a scalpel is used to gently lift the optical filter 1 from the bonding position between the DAF and the optical filter, thereby obtaining a sample after removing the optical filter 1.

[0137] Step six: the sample after removing the optical filter 1 is placed in acetone for half an hour, and then the DAF film 2 on the surface of the Die A 3 is wiped off with a cotton swab, thereby obtaining a component with the surface of the Die A exposed.

[0138] Step seven: the surface of the die is checked for abnormalities such as damage, scratches, and burns using an optical microscope. If there are no abnormalities, the Die A 3 is subjected to subsequent failure analysis and hot spot analysis.

[0139] Example 5

[0140] The embodiment provides an image sensor processing method, and the main difference from the embodiment 1 is that the baking temperature is too high, and the embodiment specifically comprises the following steps:

[0141] Step one: sample observation and measurement;

[0142] The internal structure of the image sensor sample is observed using X-ray, and the distance from the optical filter 1 to the wire 7 and the thickness of the packaging material are measured. As shown in Figure 3 The image sensor sample comprises, from top to bottom, the optical filter 1, the DAF film 2, the Die A 3, the DAF film 2, the Die B 5, and the packaging substrate 6, and the optical filter 1 is packaged with the packaging material between the edge of the optical filter 1 and the packaging substrate 6. The Die A 3 and the Die B 5 are connected to the packaging substrate 6 through the wire 7.

[0143] Step two: slotting;

[0144] According to the results of the X-Ray observation measurement in Step One, a Laser is used to open a corrosion groove 8 on the packaging material between the optical filter 1 and the wire 7 to avoid laser damage to the lower layer Die A 3 when the laser is transmitted through the optical filter 1.

[0145] The slotting position is shown in FIG. 1, where the corrosion groove 8 is arranged at one side of the optical filter 1, and the shortest distance between the corrosion groove 8 and the optical filter 1 is 50 um. Figure 4

[0146] Step Three: Acid Corrosion

[0147] Fuming nitric acid and concentrated sulfuric acid are mixed in a mass ratio of 1:1 to form a mixed acid, which is then dropped into the corrosion groove 8. The image sensor sample is then placed in a heating furnace at 100°C for 5s, and then washed with acetone.

[0148] The above dropping and washing steps are repeated 8 times to expose the DAF film 2, and a post-corrosion sample is obtained. The dropping and washing steps can ensure that the packaging material is not excessively corroded, and the corrosion is stopped when the DAF layer between the optical filter 1 and the Die A 3 is exposed.

[0149] Step Four: Baking

[0150] After the post-corrosion sample is dried, it is placed in an oven at 180°C for 4h to evaporate and remove the water vapor and washing agent introduced during the process, and a post-baking sample is obtained.

[0151] Step Five: Removing the Optical Filter 1

[0152] The post-baking sample is placed in a clamp and subjected to uniform heating to 320°C under a microscope at the position of the optical filter 1. When the DAF film 2 is slightly cracked due to high temperature, a scalpel is used to gently lift the optical filter 1 from the bonding position between the DAF and the filter, and a sample without the optical filter 1 is obtained.

[0153] Step Six: The sample without the optical filter 1 is placed in acetone for half an hour, and then the DAF film 2 on the surface of the Die A 3 is wiped off with a cotton swab, and a component with the surface of the Die A exposed is obtained.

[0154] Step Seven: The surface of the Die A is examined for abnormalities such as damage, scratches, and burns using an optical microscope. If there are no abnormalities, the Die A 3 is subjected to subsequent failure analysis and hot spot analysis.

[0155] Example 6

[0156] This example provides an image sensor processing method, which is mainly different from Example 1 in that the distance between the corrosion groove 8 and the optical filter 1 is too small, and specifically includes the following steps:

[0157] ​Step one: sample observation measurement;

[0158] First, the internal structure of the image sensor sample is observed by X-ray, and the distance from the optical filter 1 to the wire 7 and the thickness of the packaging material are measured. As shown in the structure of the image sensor sample, Figure 3 The image sensor sample includes, from top to bottom, an optical filter 1, a DAF film 2, a Die A 3, a DAF film 2, a Die B 5, and a packaging substrate 6, and the optical filter 1 is packaged with the packaging material between the edge of the optical filter 1 and the packaging substrate 6. The Die A 3 and the Die B 5 are connected to the packaging substrate 6 through the wire 7.

[0159] Step two: slotting;

[0160] According to the results of X-ray observation measurement in step one, a corrosion slot 8 is opened on the packaging material between the optical filter 1 and the wire 7 by Laser to avoid laser damage to the lower layer Die A 3 when Laser.

[0161] The slotting position is shown in Figure 4 The corrosion slot 8 is arranged on one side of the optical filter 1, and the shortest distance from the corrosion slot 8 to the optical filter 1 is 30um.

[0162] Step three: acid corrosion;

[0163] The mixed acid of fuming nitric acid and concentrated sulfuric acid with a mass ratio of 1:1 is dropped into the corrosion slot 8, and the image sensor sample is placed in a heating furnace at 100℃ for 5s, and then washed with acetone.

[0164] The above dropping and washing steps are repeated for 8 times to expose the DAF film 2, and the corrosion after sample is obtained; the dropping and washing steps are repeated to ensure that the packaging material is not over-etched, and the DAF layer between the optical filter 1 and the Die A 3 is exposed, and the corrosion is stopped.

[0165] Step four: baking;

[0166] After the corrosion after sample is dried, it is placed in an oven at 120℃ for 4h to evaporate and remove the water vapor and washing agent introduced in the process, and the baked sample is obtained.

[0167] Step five, removing the optical filter 1;

[0168] The baked sample is placed in a clamp and heated uniformly to 320℃ under a microscope at the position of the optical filter 1, and when the DAF film 2 is slightly cracked due to high temperature, the optical filter 1 is removed by gently lifting it up with a scalpel from the bonding position of the DAF and the optical filter, and the sample after removing the optical filter 1 is obtained.

[0169] Step six, the sample after removing the filter 1 is soaked in acetone for half an hour, then the DAF film 2 on the surface of the Die A 3 is wiped off with a cotton swab, and a Die A surface exposed assembly is obtained.

[0170] Step seven, the Die A surface is observed by an optical microscope to check whether there is any abnormality, such as damage, scratch, burn, etc., and if there is no abnormality, the Die A 3 is subjected to subsequent failure analysis and hot spot analysis.

[0171] Example 7

[0172] The embodiment provides an image sensor processing method, and the main difference from the embodiment 1 is that the heating step temperature is too low, and the embodiment specifically comprises the following steps.

[0173] Step one: sample observation and measurement;

[0174] The internal structure of the image sensor sample is observed by X-ray, and the distance from the filter 1 to the wire 7 and the thickness of the packaging material are measured. As shown in the structure of the image sensor sample, Figure 3 the image sensor sample comprises, from top to bottom, the filter 1, the DAF film 2, the Die A 3, the DAF film 2, the Die B 5 and the packaging substrate 6, and the filter 1 edge and the packaging substrate 6 are packaged by the packaging material, and the Die A 3 and the Die B 5 are connected to the packaging substrate 6 through the wire 7.

[0175] Step two: slotting;

[0176] According to the results of the X-ray observation and measurement in step one, a corrosion slot 8 is formed on the packaging material between the filter 1 and the wire 7 by using a laser, so as to avoid laser damage to the lower Die A 3 when the laser is transmitted through the filter 1.

[0177] The slotting position is shown in the figure, Figure 4 the corrosion slot 8 is arranged on one side of the filter 1, and the shortest distance between the corrosion slot 8 and the filter 1 is 50 um.

[0178] Step three: acid corrosion;

[0179] The fuming nitric acid and the concentrated sulfuric acid are mixed according to the mass ratio of 1:1 to form a mixed acid, which is dropped into the corrosion slot 8, and the image sensor sample is placed on a heating furnace at 100℃ for 5s, and then washed with acetone.

[0180] The above dropping and washing steps are repeated for 8 times, so that the DAF film 2 is exposed, and a corroded sample is obtained; the dropping and washing steps are repeated to ensure that the packaging material is not excessively corroded, and the corrosion is stopped when the DAF layer between the filter 1 and the Die A 3 is exposed.

[0181] Step four: baking;

[0182] The etched sample was dried and baked in an oven at 120°C for 4h to evaporate the water vapor and washing agent introduced during the process, obtaining a baked sample.

[0183] Step five: removing the filter 1;

[0184] The baked sample was placed in a clamp and heated uniformly to 290°C under a microscope at the position of the filter 1. When the DAF film 2 cracked due to high temperature, a scalpel was used to gently lift the filter 1 from the bonding position between the DAF and the filter, obtaining a sample without the filter 1.

[0185] Step six: the sample without the filter 1 was soaked in acetone for half an hour, and then the DAF film 2 on the surface of Die A3 was wiped off with a cotton swab, obtaining a Die A surface exposed assembly.

[0186] Step seven: the Die A surface was examined for abnormalities such as damage, scratches, burns, etc. using an optical microscope. If there were no abnormalities, the Die A3 was subjected to subsequent failure analysis and hot spot analysis.

[0187] Comparative Example 1

[0188] This comparative example provides an image sensor processing method, the main difference from Example 1 being that steps one and two are omitted, specifically including the following steps:

[0189] Step one: acid etching;

[0190] Fuming nitric acid and concentrated sulfuric acid were mixed in a mass ratio of 1:1 and dropped onto the image sensor sample, and the image sensor sample was heated in a heating furnace at 100°C for 5s, then washed with acetone.

[0191] The above steps of dropping the mixed acid and washing were repeated 15 times to expose the DAF film 2, obtaining an etched sample;

[0192] Step two: baking;

[0193] The etched sample was dried and baked in an oven at 120°C for 4h to evaporate the water vapor and washing agent introduced during the process, obtaining a baked sample.

[0194] Step three: removing the filter 1;

[0195] Put the baked sample into the clamp, and place it under the microscope to uniformly heat the position where the filter 1 is located to 320°C. When the DAF film 2 is slightly cracked due to high temperature, gently lift the DAF film 2 from the bonding position between the DAF film and the filter 1 with a scalpel, remove the filter 1, and obtain the sample after removing the filter 1.

[0196] Step four, after soaking the sample after removing the filter 1 in acetone for half an hour, wipe off the DAF film 2 on the surface of the Die A 3 with a cotton swab, and obtain the assembly with the die surface exposed.

[0197] Step five, use an optical microscope to check whether there is any abnormality, such as damage, scratch, burn, etc., on the die surface. If there is no abnormality, carry out subsequent failure analysis and hot spot analysis on the Die A 3.

[0198] Comparative Example 2

[0199] This comparative example provides an image sensor processing method, which mainly differs from Example 1 in that step four is omitted, and specifically includes the following steps:

[0200] Step one: sample observation and measurement;

[0201] First, use X-ray to observe the internal structure of the image sensor sample, measure the distance from the filter 1 to the wire 7, and measure the thickness of the packaging material. As shown in Figure 3 , the image sensor sample includes, from top to bottom, the filter 1, the DAF film 2, the Die A 3, the DAF film 2, the Die B 5, and the packaging substrate 6, and the filter 1 edge and the packaging substrate 6 are packaged with packaging material, and the Die A 3 and the Die B 5 are connected to the packaging substrate 6 through the wire 7.

[0202] Step two: slotting;

[0203] According to the results of X-ray observation and measurement in step one, a corrosion slot 8 is formed on the packaging material between the filter 1 and the wire 7 by laser to avoid damage to the lower Die A 3 when the laser passes through the filter 1.

[0204] The slotting position is shown in Figure 4 , the corrosion slot 8 is arranged on one side of the filter 1, and the shortest distance between the corrosion slot 8 and the filter 1 is 50 um.

[0205] Step three: acid etching;

[0206] A mixed acid of fuming nitric acid and concentrated sulfuric acid with a mass ratio of 1:1 is dropped into the corrosion slot 8, and the image sensor sample is placed in a heating furnace at 100°C for 5s, and then washed with acetone.

[0207] The above steps of dropping mixed acid and rinsing were repeated 8 times to expose the DAF film 2 to obtain a post-corrosion sample; the steps of dropping mixed acid and rinsing were repeated to ensure that the packaging material was not excessively corroded, and the corrosion was stopped when the DAF layer between the filter 1 and the Die A 3 was exposed.

[0208] Step four: removing the filter 1;

[0209] The post-baking sample was placed in a clamp and subjected to uniform heating to 320°C under a microscope at the position of the filter 1. When the DAF film 2 was slightly cracked due to high temperature, a scalpel was used to gently lift the filter 1 from the bonding position between the DAF and the filter, and a sample without the filter 1 was obtained.

[0210] Step five: the sample without the filter 1 was placed in acetone for half an hour, and then the DAF film 2 on the surface of the Die A 3 was wiped off with a cotton swab to obtain a component with the surface of the Die A exposed.

[0211] Step six: an optical microscope was used to check whether there were any abnormalities, such as damage, scratches, burns, etc., on the surface of the Die A 3, and if there were no abnormalities, subsequent failure analysis and hot spot analysis were performed on the Die A 3.

[0212] Comparative Example 3

[0213] This comparative example provides an image sensor processing method, which mainly differs from Example 1 in that the heating temperature in step five is too short, and specifically includes the following steps:

[0214] Step one: sample observation and measurement;

[0215] The internal structure of the image sensor sample was observed using X-ray, and the distance from the filter 1 to the wire 7 and the thickness of the packaging material were measured. As shown in Figure 3 , the image sensor sample includes, from top to bottom, the filter 1, the DAF film 2, the Die A 3, the DAF film 2, the Die B 5, and the packaging substrate 6, and the filter 1 edge and the packaging substrate 6 are packaged with packaging material, and the Die A 3 and the Die B 5 are connected to the packaging substrate 6 through the wire 7.

[0216] Step two: slotting;

[0217] According to the results of X-ray observation and measurement in step one, a corrosion slot 8 was formed on the packaging material between the filter 1 and the wire 7 using a laser to avoid damage to the lower Die A 3 when the laser passes through the filter 1.

[0218] The slotting position is as shown in Figure 4As shown, the etching groove 8 is arranged at one side of the optical filter 1, and the shortest distance between the etching groove 8 and the optical filter 1 is 50 um.

[0219] Step three: acid etching;

[0220] The mixed acid of fuming nitric acid and concentrated sulfuric acid with a mass ratio of 1:1 is dropped into the etching groove 8, and the image sensor sample is placed on a heating furnace at 100°C for heating for 5s, and then washed with acetone.

[0221] The above dropping and washing steps are repeated for 8 times to expose the DAF film 2 to obtain an etched sample. The repeated dropping and washing steps can ensure that the packaging material is not excessively etched, and the etching is stopped when the DAF layer between the optical filter 1 and the Die A 3 is exposed.

[0222] Step four: baking;

[0223] After the etched sample is dried, it is placed in an oven at 120°C for 4h to evaporate and remove the water vapor and washing agent introduced during the process, thereby obtaining a baked sample.

[0224] Step five: removing the optical filter 1;

[0225] The baked sample is placed in a clamp and subjected to uniform heating to 320°C for 5min under a microscope at the position of the optical filter 1. When the DAF film 2 has not yet produced fine cracks, the optical filter 1 is removed by lifting it up from the bonding position between the DAF and the optical filter with a scalpel, thereby obtaining a sample after removing the optical filter 1.

[0226] Step six: the sample after removing the optical filter 1 is placed in acetone for half an hour, and then the DAF film 2 on the surface of the Die A 3 is wiped off with a cotton swab, thereby obtaining a Die A surface exposed assembly.

[0227] Step seven: the Die A surface is checked for abnormalities such as damage, scratches, burns, etc. using an optical microscope. If there is no abnormality, the Die A 3 is subjected to subsequent failure analysis and hot spot analysis.

[0228] The qualified conditions of the Die A or the Die surface exposed assembly obtained in each of the above examples and comparative examples are shown in Table 1.

[0229] Table 1

[0230]

[0231] Note: 10 image sensors are processed in each example or comparative example to obtain 10 die surface exposed assembly samples, and the qualified rate refers to the percentage of the number of qualified samples in the total number of samples;

[0232] Wherein the qualified means the components without filter and the die surface exposed can be tested by subsequent hot spot test.

[0233] As can be seen from Table 1, the filter can be completely removed in Examples 1-3, and the die samples (Die A or Die B) are not damaged, and all the obtained die samples can be tested by subsequent hot spot test; the individual parameters such as baking time, baking temperature, distance between etching tank 8 and filter 1, heating step temperature, etc. are not reasonable in Examples 4-7, although qualified die samples can be obtained for subsequent test, but the qualified rate is reduced; all the die samples obtained in Comparative Examples 1-3 are damaged and cannot be tested by hot spot test, which shows that the slotting, baking water vapor and heating step are important for obtaining qualified die samples.

[0234] The preferred embodiments of the present application have been described above with the preferred embodiments, but not for limiting the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An image sensor processing method, wherein the image sensor comprises a filter, a DAF film, a bare die, and a packaging substrate arranged sequentially, characterized in that, The method includes: Grooving: Etching grooves are created on the encapsulation material between the filter and the wire bonding of the image sensor sample. Acid etching involves adding acid to the etching tank to etch and clean the encapsulation material, exposing the DAF film to obtain a etched sample. Baking: The corroded sample is baked to obtain a baked sample; The filter is peeled off by heating the area where the filter is located in the baked sample until the DAF film in contact with the filter cracks, thus separating the filter and obtaining the sample after removing the filter. Remove the DAF film from the surface of the bare die in the sample after removing the filter to obtain a component with the bare die surface exposed.

2. The image sensor processing method according to claim 1, characterized in that, The baking temperature is 115℃-125℃, and the baking time is 3.5h-4.5h.

3. The image sensor processing method according to claim 1, characterized in that, The distance between the corrosion tank and the filter is greater than a preset value; And / or, before the grooving step, X-ray is used to observe the distance between the filter and the wire bonding in the image sensor sample, as well as the thickness of the encapsulation material, to avoid laser damage to the bare die during grooving.

4. The image sensor processing method according to claim 1, characterized in that, The etching groove is formed on at least one side of the filter.

5. The image sensor processing method according to claim 1, characterized in that, The acid solution includes at least one of fuming nitric acid and concentrated sulfuric acid; And / or, the corrosion step is repeated more than twice, with a corrosion temperature of 95℃-105℃ and a corrosion time of 4s-6s each time.

6. The image sensor processing method according to claim 1, characterized in that, The cleaning agent used in the cleaning step is selected from at least one of acetone and alcohol; And / or, each corrosion corresponds to a cleaning step; And / or, the etched sample is dried before baking; And / or, the heating temperature of the heating step is 300℃-350℃; And / or, in the heating step, a heat source is used to uniformly heat each position of the filter.

7. The image sensor processing method according to claim 1, characterized in that, The DAF film removal process includes: immersing the sample after removing the filter in a solvent, and then peeling off the DAF film from the surface of the bare die to obtain the component with the bare die surface exposed.

8. The image sensor processing method according to claim 7, characterized in that, The solvent is selected from acetone; And / or, soaking time is 25-35 minutes.

9. A method for analyzing an image sensor, characterized in that, include: An analysis is performed on the components with exposed die surfaces obtained in the image sensor processing method according to any one of claims 1-8.

10. The method for image sensor analysis according to claim 9, characterized in that, The image sensor, from top to bottom, includes a filter, a DAF film, a bare die A, a DAF film, a bare die B, and a packaging substrate. After the surface of the bare die A is exposed using the image sensor processing method, the bare die A is analyzed. After the analysis of the bare die A is completed, the DAF films on the surfaces of the bare die A and the bare die B are peeled off to expose the surface of the bare die B, and then the bare die B is analyzed.

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