Wafer rounding processing technology

Abstract

The invention provides a wafer rounding processing technology which comprises the following steps: step 1, laser cutting: a wafer is placed on a cutting platform, and equipment cuts the wafer through a designed route; step 2, corrosion: a radian gap is formed in the surface of the wafer after laser cutting, the whole wafer is put into an acid solution to be corroded, and a notch is formed; 3, film coating is conducted, specifically, the corroded and cleaned product is subjected to film coating again; and 4, splitting: putting the coated sheet on a platform, and splitting at high temperature. According to the invention, follow-up splinters in the corrosion process cannot be broken, no cracking point exists after splinters are cracked, and then film expansion is carried out to stretch and separate the product from the rim charge, so that the subsequent operation is facilitated, the coating yield is improved, the number of operators is reduced, automation is realized, and the equipment and labor costs are greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronics, and particularly relates to a wafer rounding processing technology for improving product yield and reducing costs through laser cutting. Background Art

[0002] The introduction of glass substrates in the packaging field is an important technological innovation. Glass substrates have the following outstanding advantages: 1) High flatness and low roughness: Glass substrates have high surface flatness and low roughness, providing an ideal platform for the manufacture of micro-sized semiconductor devices. The spacing between the openings of the glass substrate is less than 100 microns, far exceeding that of organic panels, greatly improving the interconnection density between wafers. 2) Thermal stability and low coefficient of thermal expansion (CTE): Glass substrates have strong thermal stability, can maintain stable performance in high-temperature environments, and their coefficient of thermal expansion is close to that of silicon, helping to reduce stress problems caused by thermal mismatch during packaging and effectively solving the problem of 3D-IC stacking distortion. 3) High dielectric constant and low dielectric loss: Glass materials are insulator materials, with a dielectric constant only about 1 / 3 of that of silicon materials and a loss factor 2-3 orders of magnitude lower than that of silicon materials, greatly reducing substrate loss and parasitic effects and effectively improving the integrity of transmitted signals. 4) Chemical stability and corrosion resistance: Glass substrates have excellent chemical stability, can effectively resist environmental erosion such as moisture, acids, and alkalis, and ensure the long-term stability of components inside the package. 5) High transparency and optical properties: For packaging applications that require transparent windows or involve optical communication, the high transparency and excellent optical properties (such as adjustable refractive index) of glass substrates have unique advantages. 6) Environmental protection and long-term reliability: Glass substrates usually do not contain volatile organic compounds and are more environmentally friendly. Their stable physical and chemical properties endow packaged products with excellent long-term reliability.

[0003] For rounding glass materials, the previous cutting method was to first coat the film, then paste multiple pieces into a column, and then perform inner circle cutting. This method requires multiple personnel to operate, increasing the cost of operators. Moreover, since this process coats the film first and then cuts, the coating film layer will be damaged during the cutting process, resulting in low yield. Summary of the Invention

[0004] In order to overcome the deficiencies in the prior art, the present invention provides a wafer rounding processing technology.

[0005] To achieve the above object, the present invention provides a wafer rounding processing technology, which includes the following steps: Step 1, laser cutting: Place the wafer on the cutting platform, and the device cuts along the designed route. Step 2, etching: After laser cutting, there are arc-shaped gaps on the surface of the wafer. Immerse the whole wafer in an acid solution for etching to make a notch. Step 3: Splitting: Place the processed slices on the platform and split them at high temperature.

[0006] Preferably, before performing step 3 of splitting, the product after etching and cleaning in step 2 is plated.

[0007] Preferably, the ratio of the cutting depth of the laser cutting to the thickness of the wafer is 1:(40-60), and the preferred cutting depth is 0.006mm-0.02mm.

[0008] Preferably, the corrosion is carried out in the acid solution for 20-30 minutes, and the corrosion room temperature is 20-26°C.

[0009] Preferably, the acid solution is a mixed solution of ammonium bifluoride, hydrochloric acid, hydrofluoric acid, nitric acid and water in a volume ratio of 400:30:300:30:900.

[0010] Preferably, the ratio of the corrosion depth to the thickness of the wafer is 1:(1-5).

[0011] Preferably, the laser cutting has a cutting frequency greater than or equal to 1 time.

[0012] Preferably, the split pieces are carbon dioxide split pieces, and the split temperature is 150-250°C.

[0013] Preferably, the wafer is a glass substrate.

[0014] The beneficial effects of the present invention are as follows: Laser cutting cannot achieve the high precision of straight lines when cutting curved lines. If the lines are not corroded after cutting, they will easily break, and the yield rate is only 25%. The purpose of the corrosion notch is to reduce the collapse point during the splitting process. After the corrosion process in the present invention, the subsequent splitting will not break, and there will be no collapse point after splitting. Then the film expansion is performed to stretch and separate the product from the edge material for subsequent operations, improve the coating yield, reduce the number of operators, and realize automation, which greatly reduces the cost of equipment and labor. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the notch produced after etching in the present invention.

[0016] Figure 2 These are products that have not yet been corroded after laser cutting.

[0017] Figure 3 It is the gap caused by the crack after laser cutting in the traditional method.

[0018] Figure 4 This is the surface morphology of the wafer after laser cutting.

[0019] Figure 5 It is a surface morphology diagram of the wafer after splitting.

[0020] Figure 6 It is a schematic diagram of the positions of the slits and notches after laser cutting and etching in the invention.

[0021] Figure 7 It is a measurement schematic diagram of the notch generated after etching in the invention, where a is the width and b is the depth.

[0022] Figure 8 It is the product appearance detection result in Example 2 of the present invention.

[0023] Figure 9 It is the product cracking result diagram in Example 2 of the present invention. Detailed implementation manners

[0024] To better illustrate the purpose, technical solution and advantages of the present invention, the following will further illustrate the present application in combination with specific embodiments.

[0025] The present invention is composed of the following several processes, and Processes 3, 5, and 6 can be combined into the process of the present application as needed. Specifically as follows: 1. Laser cutting: Place the wafer on the cutting platform, and the equipment cuts along the designed route. After the laser cutting operation, very fine slits will be left along the route of the laser, which can assist in subsequent cracking and splitting; 2. Etching: Make notches in the slits after laser cutting through etching. The notch is as Figure 1 shown. The acid etching ratio is (ammonium bifluoride: hydrochloric acid: hydrofluoric acid: nitric acid: water = 400:30:300:30:900), the etching room temperature is 20 - 26 °C, and the PV value of the glass surface after etching is 0.1 - 0.12λ; 3. Coating: Coat the product after cleaning after etching; 4. Splitting: Place the processed wafer on the platform and split it through a carbon dioxide splitting machine by generating high temperature; 5. Film expansion: "Film expansion" after wafer splitting usually refers to the process of increasing the distance between the chips (die) on the wafer. Film expansion can increase the spacing between the die, making it easier to identify and pick up individual die, reducing the contact between the die, and reducing the risk of damage caused by mutual collision of the die during handling; 6. Transplanting: Through a transplanting machine, transfer the wafers that have broken off from the large piece on the UV film into a box.

[0026] Example 1 The glass substrate is: D263T. The wafer is processed to be round, and the product process is: original wafer - laser cutting - etching - coating - splitting - transplanting. The specific steps are as follows. Step 1, Laser cutting: Place the wafer on the cutting platform, and the equipment cuts along the designed route. The number of cutting times is 2 times. Laser cutting is the guiding cut, and the depth of the gap after cutting is 0.01 mm. For the surface morphology, please refer to Figure 4 , Step 2, Etching: The surface of the wafer after laser cutting has a curved gap. Immerse the whole wafer in the acid solution for etching to make a notch, as shown in Figure 1 . The etching room temperature is 20 - 26 °C. The volume ratio of each component of the etching agent is: ammonium bifluoride: hydrochloric acid: hydrofluoric acid: nitric acid: water = 400:30:300:30:900. According to requirements, coat the product after cleaning after the etching in Step 2; Step 3, Die separation: Place the processed wafer on the platform, and use a carbon dioxide die separator to generate high temperature for die separation. The die separation temperature is 200 °C. The length and width of the crack are the length and width of the crack on the cross-section of the wafer after splitting the wafer. In this embodiment, the length of the crack is 0.1 mm, and the width at the maximum is 0.03 mm. Finally, expand the film and transplant it.

[0027] Figure 1 The scale of Figure 7 is 1:20, the product thickness is 0.5 mm to 0.546 mm, where the single-sided depth (one side) of the gap obtained by laser guiding cut is 0.01 mm, and the depth after etching expands from 0.01 mm (gap) to 0.1505 mm ( Figure 7 graphic depth b in

[0028] ), forming a notch with a width of 0.067 mm ( Figure 5 graphic upper edge width a in

[0029] ). The single-sided depth of the gap, notch, and the connecting part before die separation is controlled within 0.245 mm, and the surface morphology is the same as that of the laser cutting (guiding cut) in Step 1. The glass substrate is: D263T. Perform wafer rounding processing. The product process is: original wafer - laser cutting - etching - coating - die separation - transplant. The specific steps are as follows. Step 1, Laser cutting: Place the wafer on the cutting platform, and the equipment cuts along the designed route. The number of cutting times is 2 times. Laser cutting is the guiding cut, and the depth of the gap after cutting is 0.01 mm. For the surface morphology, please refer to Figure 4 .

[0030] Step 2, Etching: After laser cutting, the surface of the wafer has curved slits. The whole wafer is immersed in an acid solution for etching to create notches, as shown in Figure 1 . The etching temperature is 20 - 26 °C. The volume ratio of each component of the etching agent is: ammonium bifluoride: hydrochloric acid: hydrofluoric acid: nitric acid: water = 300:30:300:30:300. According to requirements, coat the product after cleaning after the etching in Step 2.

[0031] Step 3, Die separation: Place the processed wafer on a platform and use a carbon dioxide die separator to generate high temperature for die separation. The die separation temperature is 200 °C. The length and width of the crack represent the length and width of the crack on the cross-section of the wafer after splitting. In this embodiment, the length of the crack is 0.1 mm, and the maximum width is 0.03 mm, as shown in Figure 9 . Finally, expand the film and transplant it.

[0032] In Step 2, due to the high concentration of the acidic solution, the surface of the product is damaged after etching, and the appearance is unqualified, as shown in Figure 8 . The obtained product has a thickness of 0.45 mm to 0.48 mm, with a notch formed, a width of 0.067 mm, a depth of 0.15 mm, and the unilateral depth of the slit, notch, and the connecting part before die separation is controlled within 0.2 mm.

[0033] Example 3 The glass substrate is D263T. Perform wafer rounding processing. The product process is: original wafer - laser cutting - etching - coating - die separation - transplanting. The specific steps are as follows. Step 1, Laser cutting: Place the wafer on the cutting platform, and the equipment cuts along the designed route. The number of cutting times is 2 times. Laser cutting is pilot cutting, and the depth of the slit after cutting is 0.01 mm. For the surface morphology, see Figure 4 .

[0034] Step 2, Etching: After laser cutting, the surface of the wafer has curved slits. Immerse the whole wafer in an alkaline solution for etching. The etching temperature is 90 °C, and the time is 90 minutes. The etching agent is a 30% sodium hydroxide solution. According to requirements, coat the product after cleaning after the etching in Step 2.

[0035] Step 3, Die separation: Place the processed wafer on a platform and use a carbon dioxide die separator to generate high temperature for die separation. The die separation temperature is 200 °C. The length and width of the crack represent the length and width of the crack on the cross-section of the wafer after splitting.

[0036] In this embodiment, the length of the crack is 2 - 3 mm, and the width at the maximum point is 0.1 mm. The product thickness is 0.52 mm to 0.55 mm. Since the alkaline corrosion rate is relatively slow and it is a slow infiltration corrosion, a certain angle cannot be formed around the product, resulting in serious chipping of the product during chipping.

[0037] This application has studied the key parameters in the above process. When changing parameters such as cutting, laser, and corrosion, chipping points occur during wafer chipping. See Table 1 below for details. Table 1 , .

[0038] The purpose of the corrosion notch in the present invention is to reduce chipping points during the chipping process. After the corrosion process in the present invention, the chipping will not occur, and there will be no chipping points after chipping. Then, the film is expanded to stretch and separate the product from the edge material for subsequent operations, improving the coating yield to over 92%, reducing the number of operators, and achieving automation, which greatly reduces the equipment and labor costs.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A wafer rounding method, characterized in that: The following steps are included: Step 1: Laser cutting: Place the wafer on the cutting platform and the equipment cuts along the designed route; Step 2, etching: There are curved gaps on the surface of the wafer after laser cutting. The entire wafer is placed in an acid solution for etching to make notches; Step 3: Splitting: Place the processed slices on the platform and split them at high temperature.

2. The wafer rounding method according to claim 1, characterized in that: Before the step 3 of splitting, the product after etching in step 2 is cleaned and coated.

3. The wafer rounding method according to claim 1, characterized in that: The ratio of the cutting depth of the laser cutting to the thickness of the wafer is 1:(40-60).

4. The wafer rounding method according to claim 1, characterized in that: The corrosion time is 20-30 minutes, and the corrosion room temperature is 20-26°C.

5. The wafer rounding method according to claim 1, characterized in that: The acid solution is a mixed solution of ammonium bifluoride, hydrochloric acid, hydrofluoric acid, nitric acid and water in a volume ratio of 400:30:300:30:

900.

6. The wafer rounding method according to claim 4 or 5, characterized in that: The ratio of the corrosion depth to the thickness of the wafer is 1:(1-5).

7. The wafer rounding method according to claim 3, characterized in that: The laser cutting has a cutting frequency greater than or equal to 1 time.

8. The wafer rounding method according to claim 5, characterized in that: The split pieces are carbon dioxide split pieces, and the splitting temperature is 150°C-250°C.

9. The wafer rounding method according to claim 1, characterized in that: The wafer is a glass substrate.

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