Method for detecting back surface of chip by penetrating and cutting adhesive tape

Abstract

The invention discloses a method for detecting the back surface of a chip by penetrating and cutting an adhesive tape, which comprises the following steps of: placing the adhesive tape with a chip on the front surface at a station, covering a liquid medium on the back surface of the adhesive tape to form a filling and leveling layer, covering a light-transmitting plate on the filling and leveling layer, and finally performing image acquisition on the back surface of the adhesive tape by using an imaging unit to obtain image data of the back surface of the chip. The back surface of the cutting adhesive tape is coated with a layer of liquid medium of which the refractive index is similar to that of an adhesive tape material, and any unevenness on the surface of the adhesive tape can be automatically filled with the liquid medium under the action of gravity, so that additional refraction and deflection of light rays caused by the surface forms are eliminated. The method effectively solves the problem of image degradation caused by the surface morphology of the adhesive tape in the traditional detection process.

Description

Technical Field

[0001] The invention relates to the technical field of chip backside detection methods, and in particular to a method for detecting the backside of a chip through a dicing tape. Background Art

[0002] Wafer dicing is the process of cutting a large silicon wafer into individual chips. During the dicing process, the wafer will be stuck to the dicing tape to prevent it from moving. After dicing, there may be defects such as cracks and chipping on the back of the chip, so it is necessary to inspect the back of the diced chip.

[0003] Currently, there are two main automated optical inspection (AOI) methods for the back side of cut chips: 1. Using the short-wave infrared (SWIR) band (e.g. 1050-1350nm) to penetrate semiconductor materials such as silicon, the back side of the chip is inspected from the front side. This method requires the use of SWIR band light sources, lenses and image sensors, so its cost is high and the imaging resolution is low. 2. Using crystal separation equipment to transfer the cut independent chips from the tape to other carriers, and turning the chip over so that its back side is directly exposed to the imaging unit for inspection. This method requires an additional crystal separation step, so it is inefficient and not suitable for large-scale inspection.

[0004] In order to balance efficiency and cost, the most ideal detection method is to directly penetrate the dicing tape from the back to inspect the chip. However, most of the dicing tapes widely used on the market have an uneven surface morphology. When inspected from the back, it is located between the chip and the imaging unit, which will interfere with the imaging light beam entering the imaging unit, degrading the chip image and causing image blur, distortion and other abnormalities. Summary of the invention

[0005] Therefore, in order to solve the above problems, the object of the present invention is to provide a method for penetrating a dicing tape to detect the back side of a chip, comprising the following steps: S1: Place the tape with the chip on the front side at the work station; S2: Cover the back of the tape with a liquid medium to form a filling layer; S3: Covering the filling layer with a light-transmitting plate; S4: Use an imaging unit to capture an image of the back side of the tape to obtain image data of the back side of the chip.

[0006] Preferably, the liquid medium is one of glycerol, deionized water and alcohol.

[0007] Preferably, the light-transmitting plate is made of one of quartz, plastic and glass.

[0008] Preferably, the tape is mounted on a carrier via a tape frame, and the carrier can move in two orthogonal directions.

[0009] Preferably, the tape frame is one of a mother-and-child ring and an iron ring.

[0010] The beneficial effects of the present invention are: By coating a layer of liquid medium with a refractive index close to that of the tape material on the back of the cutting tape, the liquid will automatically fill any unevenness on the tape surface under the action of gravity, thereby eliminating the additional refraction and deflection of light by these surface morphologies. This method effectively solves the problem of image degradation caused by the tape surface morphology in the traditional inspection process. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0012] Figure 1 It is an operation flow chart; Figure 2 is a schematic diagram of the present invention; Figure 3 It is a structural schematic diagram of the present invention; Figure 4 It is a structural schematic diagram of the present invention; Explanation of the accompanying drawings: 1. Imaging unit; 2. Tape frame; 3. Tape; 301. Front side of tape; 302. Back side of tape; 4. Chip after cutting; 5. Transparent plate; 6. Liquid medium.

[0013] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0015] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0016] Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0017] Embodiment 1: Figure 1-Figure 4 A method for penetrating a dicing tape to detect the back side of a chip provided by the present invention is shown, comprising the following steps: The dicing tape with the cut die on the front is mounted on a dedicated tape frame and fixed on a stage that can move in two orthogonal directions. This enables comprehensive scanning inspection of all the dies on the entire wafer.

[0018] The tape frame can be selected in the form of parent-child rings, iron rings, etc. to ensure stability and ease of operation.

[0019] Select a liquid medium with a refractive index close to that of the cutting tape material, such as glycerin, deionized water, alcohol or other mixtures. The tape in this embodiment is made of PVC, and its refractive index is 1.54, so glycerin with a refractive index of 1.47 is selected as the liquid medium in this embodiment.

[0020] The liquid medium is covered by spraying or spin coating to ensure that its thickness is at least greater than the PV value of the peak and valley of the back surface of the tape, and the coverage area exceeds the field of view of the imaging unit, so as to automatically fill any unevenness on the surface of the tape, achieve a planarization effect, and reduce additional refraction and deflection of light.

[0021] Select a light-transmitting plate with a transmittance greater than 85%. The material can be quartz, plastic (such as PMMA), glass (such as K9), and the thickness is between 0.01~1mm.

[0022] The light-transmitting plate is placed on top of the liquid medium to restrict liquid flow, prevent evaporation, and provide a stable platform for subsequent imaging.

[0023] The imaging unit includes components such as a light source, a lens (preferably a microscope lens, but it can also be a zoom lens or a telecentric lens), an image sensor (preferably an area array camera, but it can also be a line scan camera or a single point sensor), and a host computer, which are used to realize image acquisition, processing, storage and display functions.

[0024] The imaging unit collects images of the back of the dicing tape through the light-transmitting plate and the liquid medium. Since the liquid medium and the light-transmitting plate work together to eliminate the influence of the tape surface morphology, high-quality chip back image data can be obtained for analysis.

[0025] The imaging unit is fixed, and by controlling the precise movement of the stage along the X-axis and Y-axis, each chip is brought into the field of view of the imaging unit in turn for inspection.

[0026] The present invention not only solves the high cost or low efficiency problems of traditional methods, but also achieves high-resolution chip back imaging through simple and effective physical means, which is suitable for industrial-grade large-scale detection needs. At the same time, it retains the state of the chip adhering to the dicing tape in the original process, does not require additional transfer steps, and improves the overall production fluency and reliability.

[0027] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for penetrating dicing tape to detect the back side of a chip, characterized in that: The following steps are involved: S1: Place the tape with the chip on the front side at the work station; S2: Cover the back of the tape with a liquid medium to form a filling layer; S3: Covering the filling layer with a light-transmitting plate; S4: Use an imaging unit to capture an image of the back side of the tape to obtain image data of the back side of the chip.

2. The method for penetrating dicing tape to detect the back side of a chip according to claim 1, characterized in that: The liquid medium is one of glycerol, deionized water and alcohol.

3. The method for penetrating dicing tape to detect the back side of a chip according to claim 1, characterized in that: The material of the light-transmitting plate is one of quartz, plastic and glass.

4. The method for penetrating dicing tape to detect the back side of a chip according to claim 1, characterized in that: The tape is mounted on a carrier via a tape frame, and the carrier can move in two orthogonal directions.

5. The method for penetrating dicing tape to detect the back side of a chip according to claim 4, characterized in that: The tape frame is one of a mother-and-child ring and an iron ring.

Images