Wafer modification process

Abstract

The application provides a wafer modification process, which comprises the following steps: step 1, laser cutting: placing a wafer on a cutting platform, and cutting by a designed route; step 2, etching: placing the wafer after laser cutting into an acid solution to etch the wafer to form a notch; step 3, coating: coating the product after etching and cleaning; and step 4, wafer splitting: placing the wafer after coating on a platform, and splitting the wafer at high temperature. According to the application, the wafer after the etching process will not be damaged during the subsequent wafer splitting, the wafer will not be damaged after splitting, then the product and the edge material are stretched and separated by film expansion, which is convenient for subsequent operation, improves the coating yield, reduces the number of operators, realizes automation, and greatly reduces the cost of equipment and labor.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of optical optoelectronic technology, and particularly relates to a wafer modification processing technology for improving product yield and reducing cost through laser cutting. BACKGROUND

[0002] The introduction of glass substrates in the packaging field is a major technological innovation. Glass substrates have the following outstanding advantages:

[0003] 1) High flatness and low roughness: Glass substrates have high surface flatness and low roughness, providing an ideal platform for the manufacture of small-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 and can maintain stable performance in high-temperature environments. Their coefficient of thermal expansion is close to that of silicon, which helps to reduce stress problems caused by thermal mismatch during packaging and effectively solves the problem of 3D-IC stacking distortion. 3) High dielectric constant and low dielectric loss: Glass material is an insulator material with a dielectric constant about 1 / 3 of that of silicon and a loss factor 2-3 orders of magnitude lower than that of silicon, 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 and can effectively resist environmental erosion such as moisture, acid and alkali to ensure the long-term stability of components within 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 generally do not contain organic volatile substances, making them more environmentally friendly. Their stable physical and chemical properties give the packaging product excellent long-term reliability.

[0004] For glass material modification, the previous cutting method is to first coat a film, then paste multiple pieces into a column shape, and then perform inner circle cutting. This method requires multiple personnel to operate, increasing the cost of operating personnel, and since the film is coated before cutting, the film layer is damaged during cutting, resulting in low yield. SUMMARY

[0005] In order to overcome the deficiencies in the prior art, the present application provides a wafer modification processing technology.

[0006] To achieve the above purpose, the present application provides a wafer modification processing technology, which comprises the following steps,

[0007] Step 1, laser cutting: place the wafer on the cutting platform, and the equipment cuts according to the designed route;

[0008] Step 2, etching: the surface of the wafer after laser cutting has an arc-shaped gap, the wafer is put into an acid solution for etching to make a notch.

[0009] Step 3, splitting: the processed wafer is placed on a platform and split at high temperature.

[0010] Preferably, the product after step 2 etching and cleaning is coated before step 3 splitting.

[0011] Preferably, the laser cutting has a cutting depth to wafer thickness ratio of 1:(40-60), preferably the cutting depth is 0.006mm-0.02mm.

[0012] Preferably, the etching in the acid solution is performed for 20-30min at a room temperature of 20-26℃.

[0013] Preferably, the acid solution is a mixed solution of ammonium fluoride, hydrochloric acid, hydrofluoric acid, nitric acid and water in a volume ratio of 400:30:300:30:900.

[0014] Preferably, the etching has an etching depth to wafer thickness ratio of 1:(1-5).

[0015] Preferably, the laser cutting is performed more than or equal to 1 time.

[0016] Preferably, the splitting is carbon dioxide splitting at a temperature of 150-250℃.

[0017] Preferably, the wafer is a glass substrate.

[0018] The beneficial effects of the present application are as follows:

[0019] The laser cutting has an arc-shaped line that cannot achieve the high precision of a straight line, and if it is not etched after cutting, it will easily collapse, with a yield of only 25%. The purpose of etching the notch is to reduce the collapse point during splitting. After the etching process in the present application, the splitting will not collapse, and there will be no collapse point after splitting. Then, the product is stretched and separated from the edge material by expanding the film, which facilitates subsequent operations, improves the coating yield, reduces the number of workers, realizes automation, and greatly reduces the cost of equipment and labor. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The notch produced after etching in the present application.

[0021] Figure 2 The product after laser cutting but before etching.

[0022] Figure 3 The gap after laser cutting in the traditional method.

[0023] Figure 4 The surface morphology of the wafer after laser cutting.

[0024] Figure 5 The surface morphology of the wafer after wafer splitting.

[0025] Figure 6 The schematic diagram of the position of the gap and notch after laser cutting and etching in the application.

[0026] Figure 7 The measurement schematic diagram of the notch generated after etching in the application, a is the width, and b is the depth.

[0027] Figure 8 The product appearance detection result in embodiment 2 of the application.

[0028] Figure 9 The product cracking result diagram in embodiment 2 of the application. DETAILED DESCRIPTION

[0029] In order to better illustrate the purpose, technical scheme and advantages of the application, the application will be further described below in combination with specific embodiments.

[0030] The application is composed of the following processes, and processes 3, 5 and 6 can be combined into the process of the application as needed. Specifically, the following is shown:

[0031] 1. Laser cutting: Place the wafer on the cutting platform, and the equipment cuts through the designed route. After the laser cutting operation is completed, there will be very small gaps along the route of the laser, which can assist in subsequent splitting and segmentation.

[0032] 2. Etching: The gap after laser cutting is made into a notch through etching. The notch is shown in Figure 1 The acid etching ratio is (ammonium hydrogen fluoride: hydrochloric acid: hydrofluoric acid: nitric acid: water = 400:30:300:30:900). The etching room temperature is 20-26 degrees Celsius. The glass surface PV value after etching is 0.1-0.12 lambda.

[0033] 3. Coating: The product after cleaning after etching is coated again.

[0034] 4. Splitting: Place the processed wafer on the platform, and use a carbon dioxide wafer splitting machine to generate high temperature for wafer splitting.

[0035] 5. Expanding film: The "expanding film" of the wafer after splitting usually refers to the process of expanding the distance between the chips (die) on the wafer. Expanding the film can increase the distance between the die, making it easier to identify and pick up individual die, reducing the risk of damage caused by mutual collision of the die during handling.

[0036] 6. Transplanting: Use a transplanting machine to move the discs that have been broken off from the large piece of UV film into the box.

[0037] Example 1

[0038] The glass substrate is D263T, and the wafer is rounded. The product process is: original wafer - laser cutting - corrosion - coating - cracking - transplanting. The specific steps are as follows:

[0039] Step 1, laser cutting: Place the wafer on the cutting platform, and the equipment cuts along the designed route. Cutting times: 2. Laser cutting is a lead-in process, and the depth of the gap after cutting is 0.01mm. See the surface morphology for details. Figure 4 ,

[0040] Step 2, etching: After laser cutting, there are arc gaps on the surface of the wafer. Put the wafer into the acid solution for etching to make grooves. Figure 1 The etching temperature is 20-26 degrees Celsius. The volume ratio of the etching agent is: ammonium bifluoride: hydrochloric acid: hydrofluoric acid: nitric acid: water = 400:30:300:30:900. If necessary, the product after etching and cleaning in step 2 can be coated;

[0041] Step 3: Splitting: The processed sheet is placed on a platform and split using a CO2 splitter at a high temperature of 200°C. The length and width of the cracks represent the length and width of the cracks in the cross-section of the sheet after the sheet is split. In this example, the crack length is 0.1mm, and the maximum width is 0.03mm. Finally, the film is expanded and transplanted.

[0042] Figure 1 The scale is 1:20, the product thickness is 0.5mm to 0.546mm, of which the single-side depth of the laser-cut gap (single side) is 0.01mm, and the depth after corrosion is expanded from 0.01mm (gap) to 0.1505mm ( Figure 7 The depth of the middle pattern is b), forming a notch with a width of 0.067mm ( Figure 7 The width a of the upper edge of the middle figure is controlled at 0.245 mm on one side of the gap, notch, and front connection of the split. The surface morphology is consistent with the laser cutting (lead cutting) in step 1.

[0043] Since the coating is performed after etching, the coating thickness is 12nm. The coating area and the depth of the fracture after the crack are 12nm. The surface morphology is shown in Figure 5 The middle circle in the picture shows the bubbles when the UV film is applied. The coating is evenly coated on the glass substrate, including the notch. If the glass cracks, only the coating layer at the notch will be damaged, and the surface coating layer will not be damaged.

[0044] Example 2

[0045] The glass substrate is D263T, and wafer-to-round processing is performed. The product flow is: original wafer-laser cutting-etching-coating-cracking-transplanting. The specific steps are as follows,

[0046] Step 1, laser cutting: place the wafer on the cutting platform, and the equipment cuts according to the designed route, with 2 cutting times. The laser cutting is a lead cut, and the depth of the gap after cutting is 0.01 mm. The surface morphology is shown in Figure 4 .

[0047] Step 2, etching: the wafer after laser cutting has an arc gap, and the wafer is placed in an acid solution for etching. The notch is made by etching, as shown in Figure 1 . The etching temperature is 20-26 degrees Celsius, and the volume ratio of each component of the etching agent is: ammonium fluoride: hydrochloric acid: hydrofluoric acid: nitric acid: water = 300:30:300:30:300. According to the needs, the product after step 2 etching and cleaning is coated.

[0048] Step 3, cracking: place the processed wafer on the platform, and use a carbon dioxide cracking machine to generate high temperature for cracking. The cracking temperature is 200°C. The length and width of the crack represent the length and width of the cross-section of the cracked wafer. 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, the film is expanded and transplanted.

[0049] In step 2, the product surface is damaged after etching due to high concentration of the acid solution, and the appearance is unqualified, as shown in Figure 8 . The thickness of the obtained product is 0.45-0.48 mm, a notch is formed, the width is 0.067 mm, the depth is 0.15 mm, the gap, the notch and the single-sided depth of the connection part before cracking are controlled within 0.2 mm.

[0050] Example 3

[0051] The glass substrate is D263T, and wafer-to-round processing is performed. The product flow is: original wafer-laser cutting-etching-coating-cracking-transplanting. The specific steps are as follows,

[0052] Step 1, laser cutting: place the wafer on the cutting platform, and the equipment cuts according to the designed route, with 2 cutting times. The laser cutting is a lead cut, and the depth of the gap after cutting is 0.01 mm. The surface morphology is shown in Figure 4 .

[0053] Step 2, etching: the surface of the wafer after laser cutting has an arc-shaped gap, and the wafer is placed in an alkaline solution for etching. Etching temperature: 90 degrees Celsius, time: 90 minutes. The etching agent is a 30% concentration sodium hydroxide solution. According to the needs, the product after cleaning after step 2 etching is coated.

[0054] Step 3, splitting: the processed wafer is placed on a platform and split by a carbon dioxide splitter by generating high temperature. Splitting temperature: 200℃. The length and width of the crack represent the length and width of the cross-section of the wafer after splitting.

[0055] The length of the crack in this embodiment is 2-3mm, and the maximum width is 0.1mm. The product thickness is 0.52mm to 0.55mm. Because the alkaline etching rate is relatively slow, it is a slow penetration corrosion, and the product cannot form a certain angle around the product, resulting in a serious crack edge phenomenon when the product is split.

[0056] The present application studies the key parameters in the above process, and changes the cutting, laser, etching and other parameters, and the wafer splitting appears a crack point, see Table 1 below,

[0057] Table 1

[0058] ,

[0059] .

[0060] The purpose of the etching notch of the present application is to reduce the crack point during the splitting process. The wafer does not crack after the etching process in the present application, and there is no crack point after splitting. Then, the product is stretched and separated from the edge material by expanding the film, which is convenient for subsequent operation, improves the plating yield to more than 92%, reduces the number of workers, realizes automation, and greatly reduces the cost of equipment and labor.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A wafer rounding method, characterized in that: It consists of the following steps: Step 1, laser cutting: Place the wafer on the cutting platform, and the equipment cuts along the designed route; the ratio of the cutting depth to the wafer thickness is 1:(40-60); the laser cutting is a lead-in cutting, and the number of cuts is 2; the depth of the gap after cutting is 0.01mm; Step 2, etching: After laser cutting, there are curved gaps on the surface of the wafer. The wafer is placed in an acid solution for etching for 20-30 minutes at a room temperature of 20-26°C. The ratio of the etching depth to the wafer thickness is 1:(1-5) to make a notch. 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. The product after etching and cleaning is then plated. Step 3: Splitting: Place the processed slices on a platform and perform carbon dioxide splitting at high temperature, with the splitting temperature at 150℃-250℃.

2. The wafer rounding method according to claim 1, wherein: The wafer is a glass substrate.

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