Wafer particle separation method

Abstract

The present invention discloses a method for separating wafer particles, comprising the steps of: laser cutting a preset cutting path of a wafer coated with a laser cutting protective liquid according to a preset cutting depth to obtain a cut wafer, wherein the preset cutting depth is less than the thickness of the preset cutting path; cold expansion separation is performed on the cut wafer to obtain wafer particles, that is, laser cutting is first performed on the cutting path without cutting it off, but only a hole is opened to achieve the purpose of damaging the cutting path; during subsequent hidden cutting, only the inside of the wafer is modified; during cold expansion separation, since the groove position of the cutting path is fragile, the cold expansion force can be guided from the hidden cutting position to the fragile position of the cutting path, thereby separating the wafer particles more easily and avoiding chip die (wafer) cracking, thereby effectively improving the quality of wafer particle separation and further improving product yield.

Description

Technical Field

[0001] The present invention relates to the technical field of wafer cutting and processing, and in particular to a wafer particle separation method. Background Art

[0002] When using the stealth cutting process to produce wafers with tungsten bars in the cutting path or thicker circuit layers, it is difficult to separate the wafer particles due to the special situation of the cutting path, and the cutting path will collapse during separation, which can easily cause the product to be scrapped. In addition, for chips that are ground to ultra-thin (i.e., thickness below 60μm), since the chip is too thin, the stress that the chip can withstand is small. During cold expansion separation, the expansion force can easily cause the chip die (wafer) to crack. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a wafer particle separation method that can effectively improve the wafer particle separation quality.

[0004] In order to solve the above technical problems, a technical solution adopted by the present invention is:

[0005] A wafer particle separation method comprises the following steps:

[0006] Laser cutting a preset cutting line of the wafer coated with the laser cutting protection liquid according to a preset cutting depth to obtain a cut wafer, wherein the preset cutting depth is less than a thickness of the preset cutting line;

[0007] The cut wafers are then cold expanded and separated to obtain wafer particles.

[0008] The beneficial effects of the present invention are: laser cutting is performed on the preset cutting path of the wafer coated with laser cutting protective liquid according to the preset cutting depth to obtain the cut wafer, the preset cutting depth is less than the thickness of the preset cutting path, cold expansion separation is performed based on the cut wafer to obtain wafer particles, that is, the cutting path is first laser cut, and is not cut off, but only a hole is broken to achieve the purpose of damaging the cutting path. During subsequent hidden cutting, only the inside of the wafer is modified. During cold expansion separation, since the groove position of the cutting path is fragile, the cold expansion force can be directed from the hidden cutting position to the fragile position of the cutting path, which makes it easier to separate the wafer particles and avoid chip die (wafer) cracking, thereby effectively improving the quality of wafer particle separation and further improving product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a flowchart of the steps of a wafer particle separation method according to an embodiment of the present invention;

[0010] Figure 2 Schematic diagram of laser grooving in a wafer particle separation method according to an embodiment of the present invention;

[0011] Figure 3 This is a schematic diagram of a wafer particle separation method after cold expansion separation in an embodiment of the present invention. DETAILED DESCRIPTION

[0012] To illustrate the technical content, achieved objectives and effects of the present invention in detail, the following description is given in conjunction with the embodiments and accompanying drawings.

[0013] Please refer to Figure 1 , an embodiment of the present invention provides a wafer particle separation method, comprising the steps of:

[0014] Laser cutting a preset cutting line of the wafer coated with the laser cutting protection liquid according to a preset cutting depth to obtain a cut wafer, wherein the preset cutting depth is less than a thickness of the preset cutting line;

[0015] The cut wafers are then cold expanded and separated to obtain wafer particles.

[0016] From the above description, it can be seen that the beneficial effect of the present invention is that: the preset cutting road of the wafer coated with laser cutting protective liquid is laser cut according to the preset cutting depth to obtain the cut wafer, the preset cutting depth is less than the thickness of the preset cutting road, and the wafer is cold expanded and separated based on the cut wafer to obtain wafer particles, that is, the cutting road is first laser cut, and it is not cut off, but only a hole is broken to achieve the purpose of damaging the cutting road. During the subsequent hidden cutting, only the inside of the wafer is modified. During the cold expansion separation, since the groove position of the cutting road is fragile, the cold expansion force can be directed from the hidden cutting position to the fragile position of the cutting road, which makes it easier to separate the wafer particles and avoid chip die (wafer) cracking, thereby effectively improving the quality of wafer particle separation and thus improving product yield.

[0017] Furthermore, the laser cutting of the preset cutting lanes of the wafer coated with the laser cutting protection liquid according to the preset cutting depth to obtain the cut wafer includes the following steps:

[0018] A tempered film is attached to the back of the wafer to obtain a wafer with film attached;

[0019] The laser cutting protection liquid is coated on the front side of the wafer after the film is attached, so as to obtain a wafer coated with the laser cutting protection liquid.

[0020] From the above description, it can be seen that attaching a tempered film on the back of the wafer can better support the entire wafer and facilitate the operation of the wafer. The laser cutting protective liquid protects the wafer and prevents the laser from damaging the wafer except the cutting path.

[0021] Furthermore, the step of coating the front surface of the wafer after laminating the film with a laser cutting protective liquid to obtain a wafer coated with the laser cutting protective liquid comprises:

[0022] Attaching an iron ring to the back of the wafer after film lamination to obtain a wafer with an iron ring;

[0023] The front side of the wafer with the iron ring is coated with a laser cutting protection liquid to obtain a wafer coated with the laser cutting protection liquid.

[0024] From the above description, it can be seen that an iron ring is attached to the back of the wafer after film lamination. The iron ring is convenient for fixing the wafer, which is conducive to automatic laser cutting. There is no need for manual cutting of the wafer, which improves the efficiency of wafer particle separation.

[0025] Furthermore, the preset cutting depth is set to 3-20 μm.

[0026] It can be seen from the above description that a better cutting street damage effect can be achieved.

[0027] Furthermore, the tempered film is a UV film;

[0028] The step of performing cold expansion separation on the cut wafer to obtain wafer particles comprises:

[0029] Cleaning the laser cutting protection liquid on the cut wafer to obtain a cleaned wafer;

[0030] irradiating the cleaned wafer with UV light until the UV film on the surface is removed to obtain a bare wafer;

[0031] affixing a grinding protective film on the front side of the wafer bare die to obtain a re-filmed wafer;

[0032] Performing invisible laser cutting on the preset cutting path of the wafer after the film is re-laminated to obtain a wafer after invisible cutting;

[0033] Grinding the stealth-cut wafer to a target thickness to obtain a ground wafer;

[0034] The ground wafers are subjected to cold expansion separation to obtain wafer particles.

[0035] From the above description, it can be seen that UV irradiation of the cleaned wafer can remove the UV film and iron ring on the wafer, remove the wafer bare die, and attach a grinding protective film to the front of the wafer bare die to protect the front circuit layer of the wafer during back grinding, thereby improving the quality of wafer particle separation.

[0036] Furthermore, the step of cleaning the laser cutting protection liquid on the cut wafer to obtain a cleaned wafer includes:

[0037] Cleaning the laser cutting protection liquid on the cut wafer using deionized water according to a preset cleaning time to obtain a preliminarily cleaned wafer;

[0038] The preliminarily cleaned wafer is dried according to a preset drying time to obtain a cleaned wafer.

[0039] As can be seen from the above description, using deionized water to clean the laser cutting protection liquid on the cut wafer and then drying it can effectively remove the protection liquid and the residue after cutting.

[0040] Furthermore, the preset cleaning time is set to 100s;

[0041] The preset drying time is set to 30s.

[0042] It can be seen from the above description that this can achieve the best cleaning effect, thereby improving the subsequent wafer particle separation effect.

[0043] Furthermore, performing invisible laser cutting on the preset cutting path of the wafer after the film is re-laminated to obtain the wafer after invisible cutting includes:

[0044] The preset cutting path of the wafer after the film is re-laminated is subjected to invisible laser cutting using an invisible laser cutting machine according to the preset cutting energy and the corresponding preset cutting depth to obtain a wafer after invisible cutting.

[0045] From the above description, it can be seen that performing invisible laser cutting on the wafer after grooving the cutting streets can achieve more precise cutting and ensure the cutting effect.

[0046] Furthermore, the step of performing cold expansion separation on the ground wafer to obtain wafer particles comprises:

[0047] A cold expansion machine is used to perform cold expansion separation on the ground wafers according to a preset temperature and a preset cold expansion time to obtain wafer particles.

[0048] From the above description, it can be seen that using a cold expansion machine to cold expand and separate the ground wafers according to the preset temperature and preset cold expansion time can make the DAF film layer on the wafer (used to bond the chip and substrate) brittle and can be separated together with the chip (i.e., wafer particles), ensuring the quality of wafer particle separation.

[0049] Furthermore, the preset temperature is set to -15°C;

[0050] The preset cold expansion time is set to 10s.

[0051] It can be seen from the above description that the best cold expansion separation effect is achieved in this way.

[0052] The wafer particle separation method described above in the present invention can be applied to scenarios where wafer particles need to be separated, and is described below through specific implementation methods:

[0053] Example 1

[0054] Please refer to Figures 1 to 3 , a wafer particle separation method of this embodiment includes the steps of:

[0055] S1. Attaching a tempered film to the back of the wafer to obtain a wafer with film attached;

[0056] Wherein, the tempered film is a UV film;

[0057] Specifically, a UV film is attached to the back of the wafer using a film attaching machine to obtain a film-attached wafer;

[0058] In an optional embodiment, a grinding protective film is attached to the front side of the wafer and a tempered film is attached to the back side of the wafer to obtain a wafer with films attached, so that when the tempered film is attached to the back side of the wafer, the front side of the wafer is protected from wear;

[0059] S2, coating the front surface of the wafer after laminating the film with a laser cutting protective liquid to obtain a wafer coated with the laser cutting protective liquid, specifically comprising:

[0060] S21, attaching an iron ring to the back side of the wafer after film attachment to obtain a wafer with an iron ring;

[0061] S22, coating the front surface of the wafer with the iron ring with a laser cutting protection liquid to obtain a wafer coated with the laser cutting protection liquid;

[0062] S3, laser cutting the preset cutting line of the wafer coated with the laser cutting protection liquid according to a preset cutting depth to obtain a cut wafer, wherein the preset cutting depth is less than the thickness of the preset cutting line;

[0063] Wherein, the preset cutting depth is set to 3 to 20 μm;

[0064] Specifically, the preset cutting path of the wafer coated with laser cutting protection liquid is laser cut in a fully automatic laser cutting machine according to the preset cutting depth to obtain the cut wafer, such as Figure 2 As shown;

[0065] In an optional embodiment, laser cutting is performed on a predetermined cutting path of the wafer coated with laser cutting protection liquid at a cutting depth of 3 μm in a fully automatic laser cutting machine to obtain a cut wafer;

[0066] In another optional embodiment, laser cutting is performed on a predetermined cutting path of the wafer coated with the laser cutting protection liquid at a cutting depth of 10 μm in a fully automatic laser cutting machine to obtain a cut wafer;

[0067] In another optional embodiment, laser cutting is performed on a predetermined cutting path of the wafer coated with the laser cutting protection liquid at a cutting depth of 20 μm in a fully automatic laser cutting machine to obtain a cut wafer;

[0068] S4, performing cold expansion separation on the cut wafers to obtain wafer particles, specifically comprising:

[0069] S41, cleaning the laser cutting protection liquid on the cut wafer to obtain a cleaned wafer, specifically comprising:

[0070] S411, using deionized water to clean the laser cutting protection liquid on the cut wafer according to a preset cleaning time to obtain a preliminarily cleaned wafer;

[0071] Wherein, the preset cleaning time is set to 80 to 120 seconds;

[0072] Specifically, the laser cutting protection liquid on the cut wafer is cleaned with deionized water in a fully automatic laser cutting machine according to a preset cleaning time to obtain a preliminarily cleaned wafer;

[0073] In an optional embodiment, the laser cutting protection liquid on the cut wafer is cleaned with deionized water in a fully automatic laser cutting machine for a cleaning time of 100 seconds to obtain a preliminarily cleaned wafer;

[0074] In another optional embodiment, the laser cutting protection liquid on the cut wafer is cleaned with deionized water in a fully automatic laser cutting machine for 80 seconds to obtain a preliminarily cleaned wafer;

[0075] In another optional embodiment, the laser cutting protection liquid on the cut wafer is cleaned with deionized water in a fully automatic laser cutting machine according to a cleaning time of 120 seconds to obtain a preliminarily cleaned wafer; S412, the preliminarily cleaned wafer is dried according to a preset drying time to obtain a cleaned wafer;

[0076] Wherein, the preset drying time is set to 20 to 40 seconds;

[0077] Specifically, the preliminarily cleaned wafer is dried in a fully automatic laser cutting machine according to a preset drying time to obtain a cleaned wafer;

[0078] In an optional embodiment, the preliminarily cleaned wafer is dried in a fully automatic laser cutting machine for a drying time of 30 seconds to obtain a cleaned wafer;

[0079] In another optional embodiment, the preliminarily cleaned wafer is dried in a fully automatic laser cutting machine according to a drying time of 20 seconds to obtain a cleaned wafer;

[0080] In another optional embodiment, the preliminarily cleaned wafer is dried in a fully automatic laser cutting machine for a drying time of 40 seconds to obtain a cleaned wafer; S42, the cleaned wafer is subjected to UV irradiation until the UV film on the surface is removed to obtain a wafer bare die;

[0081] S43, attaching a grinding protective film to the front side of the bare wafer to obtain a re-filmed wafer;

[0082] S44, performing invisible laser cutting on the preset cutting path of the wafer after the film is re-laminated to obtain a wafer after invisible cutting;

[0083] Specifically, a stealth laser cutting machine is used to perform stealth laser cutting on the preset cutting path of the wafer after the film is re-laminated according to a preset cutting energy and a corresponding preset cutting depth in a laser stealth cutting machine to obtain a wafer after stealth cutting;

[0084] S45, grinding the wafer after stealth cutting to a target thickness to obtain a ground wafer;

[0085] Specifically, using a grinder to grind the stealth-cut wafer to a target thickness to obtain a ground wafer;

[0086] S46, performing cold expansion separation on the ground wafer to obtain wafer particles, such as Figure 3 As shown;

[0087] Specifically, a cold expansion machine is used to perform cold expansion separation on the ground wafers according to a preset temperature and a preset cold expansion time to obtain wafer particles;

[0088] The preset temperature is set to -15 to -18°C; the preset cold expansion time is set to 10 to 15 seconds;

[0089] In an optional embodiment, a cold expansion machine is used to perform cold expansion separation on the ground wafer at a temperature of -15°C and a cold expansion time of 10 seconds to obtain wafer particles;

[0090] In another optional embodiment, a cold expansion machine is used to perform cold expansion separation on the ground wafer at a temperature of -17°C and a cold expansion time of 13 seconds to obtain wafer particles;

[0091] In another optional embodiment, a cold expansion machine is used to perform cold expansion separation on the ground wafers at a temperature of -18°C and a cold expansion time of 15 seconds to obtain wafer particles.

[0092] In summary, the present invention provides a method for separating wafer particles, which performs laser cutting on a preset cutting path of a wafer coated with laser cutting protective liquid according to a preset cutting depth to obtain a cut wafer, wherein the preset cutting depth is less than the thickness of the preset cutting path; cold expansion separation is performed based on the cut wafer to obtain wafer particles, and the cutting path is first laser cut without cutting it, but only a hole is opened to achieve the purpose of damaging the cutting path. Since the groove position of the cutting path is fragile, the cutting path will not be broken during subsequent actual cutting, and an invisible laser cutting machine is used to perform invisible laser cutting on the preset cutting path of the wafer after re-filming according to the preset cutting energy and the corresponding preset cutting depth. By performing invisible laser cutting on the wafer after grooving the cutting path, more precise cutting can be achieved and the cutting effect can be ensured. During cold expansion separation, the cold expansion force can be directed to the fragile position of the cutting path, which can more easily separate the wafer particles and avoid chip die (wafer) cracking, thereby effectively improving the quality of wafer particle separation and thus improving product yield.

[0093] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A wafer particle separation method, characterized in that: Including steps: Laser cutting a preset cutting line of the wafer coated with the laser cutting protection liquid according to a preset cutting depth to obtain a cut wafer, wherein the preset cutting depth is less than a thickness of the preset cutting line; performing cold expansion separation on the cut wafers to obtain wafer particles; The laser cutting of the preset cutting path of the wafer coated with the laser cutting protection liquid according to the preset cutting depth to obtain the cut wafer includes the following steps: A tempered film is attached to the back of the wafer to obtain a wafer with film attached; Coating a laser cutting protection liquid on the front side of the wafer after laminating the film, thereby obtaining a wafer coated with the laser cutting protection liquid; The tempered film is a UV film; The step of performing cold expansion separation on the cut wafer to obtain wafer particles comprises: Cleaning the laser cutting protection liquid on the cut wafer to obtain a cleaned wafer; irradiating the cleaned wafer with UV light until the UV film on the surface is removed to obtain a bare wafer; affixing a grinding protective film on the front side of the wafer bare die to obtain a re-filmed wafer; Performing invisible laser cutting on the preset cutting path of the wafer after the film is re-laminated to obtain a wafer after invisible cutting; Grinding the stealth-cut wafer to a target thickness to obtain a ground wafer; The ground wafers are subjected to cold expansion separation to obtain wafer particles.

2. The wafer particle separation method according to claim 1, characterized in that: The method of coating the front surface of the wafer after laminating the film with a laser cutting protective liquid to obtain a wafer coated with the laser cutting protective liquid comprises: Attaching an iron ring to the back of the wafer after film lamination to obtain a wafer with an iron ring; The front side of the wafer with the iron ring is coated with a laser cutting protection liquid to obtain a wafer coated with the laser cutting protection liquid.

3. The wafer particle separation method according to claim 1, characterized in that: The preset cutting depth is set to 3-20 μm.

4. The wafer particle separation method according to claim 1, characterized in that: The step of cleaning the laser cutting protection liquid on the cut wafer to obtain a cleaned wafer includes: Cleaning the laser cutting protection liquid on the cut wafer using deionized water according to a preset cleaning time to obtain a preliminarily cleaned wafer; The preliminarily cleaned wafer is dried according to a preset drying time to obtain a cleaned wafer.

5. The wafer particle separation method according to claim 4, characterized in that: The preset cleaning time is set to 80-120s; The preset drying time is set to 20-40s.

6. The wafer particle separation method according to claim 1, characterized in that: The step of performing invisible laser cutting on the preset cutting path of the wafer after the film is re-laminated to obtain the wafer after invisible cutting comprises: The preset cutting path of the wafer after the film is re-laminated is subjected to invisible laser cutting using an invisible laser cutting machine according to the preset cutting energy and the corresponding preset cutting depth to obtain a wafer after invisible cutting.

7. The wafer particle separation method according to claim 1, characterized in that: The cold expansion separation of the ground wafer to obtain wafer particles comprises: A cold expansion machine is used to perform cold expansion separation on the ground wafers according to a preset temperature and a preset cold expansion time to obtain wafer particles.

8. The wafer particle separation method according to claim 7, characterized in that: The preset temperature is set to -15~-18℃; The preset cold expansion time is set to 10-15s.

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