CN116314033A - Wafer protection method and wafer protection structure - Google Patents

Abstract

The invention provides a wafer protection method and a wafer protection structure. By forming the protective layer on the surface of the wafer, the wafer can be conveniently stored for a long time without being influenced by the storage environment. The tiny dust, water vapor and the like in the environment cannot contact the surface of the wafer, and meanwhile, the protective layer has more advantages: quick solidification, good adhesiveness, compact film layer, water and oil repellency, easy removal, etc. Because air, water vapor and the like are isolated, chemical reaction of residual chemical solution on the surface of the electrode in the storage process is avoided, so that the electrode on the surface of the wafer is protected, and the problem that core particles fail after the electrode is corroded is avoided. The method can reduce the requirement on the wafer storage environment, lighten the use pressure of a dust-free room, and can not influence the final yield even if the wafer is stored for a long time, thereby further improving the reliability of the wafer.

Description

Wafer protection method and wafer protection structure

technical field

The invention relates to the field of semiconductor wafer manufacturing, in particular to a wafer protection method and a wafer protection structure.

Background technique

Current fabs typically store wafers in storage to protect these semi-finished layers. Affected by the storage conditions, the wafers will be directly or indirectly exposed to the atmospheric environment. Because the maintenance cost of the clean room is too high, the wafers are usually stored in ordinary warehouses. However, there is a lot of dust and water vapor in the air, even if Putting the wafer into the wafer box for storage still cannot effectively isolate the pollution of dust and water vapor. In addition, when the wafer is stored, some impurities and particles will inevitably be introduced into the wafer box, thereby causing pollution to the surface of the wafer. In particular, some particles in the air will be deposited on the surface of the wafer, which will eventually affect the yield. During storage, the electrodes (usually metal aluminum) on the surface of the die on the wafer are equivalent to being exposed to the air. Some wafers will be more affected by the storage conditions due to the long storage time, and the electrodes will also be generated. Corresponding pollution or corrosion, and these electrodes will be used to connect wires in the future, after being polluted or corroded, it is easy to cause poor contact of the welding wire, resulting in core particle failure and affecting stability. In addition, in the wafer manufacturing process, chemical solutions (such as fluoride and chloride) are usually used. These chemical solutions remain on the surface of the electrode, and under the action of air and water vapor, chemical reactions will gradually occur, further damaging the electrode. corrosion.

Therefore, it is necessary to propose a wafer protection method to protect the wafer surface.

Contents of the invention

In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a wafer protection method and a wafer protection structure, which are used to solve the problem of lack of protection and easy failure of the wafer surface in the prior art.

In order to achieve the above purpose and other related purposes, the present invention provides a wafer protection structure, the wafer protection structure comprising:

a wafer, the upper surface of the wafer has a plurality of electrodes;

A protective layer, the protective layer covers the upper surface of the wafer, so as to isolate the surface of the wafer from the outside world, and the protective layer will gradually decompose after being irradiated by ultraviolet rays or heated to facilitate peeling off.

Optionally, the protection layer is formed on the upper surface of the wafer by a spin coating method.

Optionally, the thickness of the protective layer is greater than 0.3mm.

Optionally, the material of the protective layer includes silicon dioxide and titanium dioxide.

Optionally, the protective layer is a one-layer or multi-layer structure.

The present invention also provides a wafer protection method, which includes the following steps:

S1: providing a wafer, the upper surface of the wafer has a plurality of electrodes;

S2: uniformly coating a protective solution on the upper surface of the wafer, and forming a protective layer after the protective solution is cured;

S3: When the protective layer needs to be removed, irradiate the protective layer with ultraviolet rays to gradually decompose the protective layer to facilitate peeling off.

Optionally, in step S2, the protective liquid is coated on the upper surface of the wafer by a spin coating method, and the protective liquid flows out through a nozzle. During the coating process, the wafer is rotated while the The nozzle translates from the center of the wafer to the edge of the wafer.

Optionally, the thickness of the protective layer is greater than 0.3 mm.

Optionally, the protective layer is a one-layer or multi-layer structure.

Optionally, the material of the protective layer includes silicon dioxide and titanium dioxide.

As mentioned above, the present invention provides a wafer protection method and a wafer protection structure. By forming a protective layer on the surface of the wafer, it is convenient for the wafer to be stored for a long time without being affected by the storage environment. Tiny dust and water vapor in the environment cannot contact the surface of the wafer. At the same time, the protective layer has many advantages: fast solidification, good adhesion, dense film layer, hydrophobic and oleophobic, easy to remove, etc. Because the air, water vapor, etc. are isolated, the chemical solution (such as fluoride, chloride) remaining on the electrode surface is also avoided from chemical reaction during storage, so the electrode on the wafer surface is also protected, preventing the electrode from being corroded. grain failure problem. Using this method can reduce the requirements on the wafer storage environment, reduce the use pressure of the clean room, and the final yield rate will not be affected when the wafer is stored for a long time, and the reliability of the wafer is further improved. In addition, the protective layer can be decomposed by ultraviolet irradiation or heating to facilitate peeling and removal, and the operation is convenient and the process cost is low.

Description of drawings

FIG. 1 is a schematic diagram showing the distribution of bad dies on a wafer in the prior art.

FIG. 2 shows an electron micrograph of particles attached to a wafer in the prior art.

Figure 3 shows an electron micrograph of corroded electrodes on the wafer surface.

Fig. 4 shows a schematic diagram of coating the protective solution on the surface of the wafer.

FIG. 5 shows a schematic diagram of forming a protective layer on the surface of a wafer.

Figure 6 is a schematic diagram of peeling off the protective layer.

Fig. 7 shows a schematic diagram of a structure in which the protective layer is one layer.

FIG. 8 is a schematic diagram showing a structure in which the protective layer is a multi-layer structure.

FIG. 9 is a schematic diagram showing the distribution of bad dies on the wafer in the control experiment.

Fig. 10 shows an electron micrograph of corroded electrodes on the wafer surface in the control experiment.

Component designation description

1 wafer

2 layers of protection

3 nozzles

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

For example, when describing the embodiments of the present invention in detail, for the convenience of explanation, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic diagram is only an example, which should not limit the protection scope of the present invention. In addition, the three-dimensional space dimensions of length, width and depth should be included in actual production.

For the convenience of description, spatial relation terms such as "below", "below", "below", "below", "above", "on" etc. may be used herein to describe an element or element shown in the drawings. The relationship of a feature to other components or features. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. As used herein, "between" means that both endpoints are inclusive.

In the context of this application, structures described as having a first feature "on top of" a second feature may include embodiments where the first and second features are formed in direct contact, as well as additional features formed between the first and second features. Embodiments between the second feature such that the first and second features may not be in direct contact.

It should be noted that the diagrams provided in this embodiment are only schematically illustrating the basic idea of the present invention, so that only the components related to the present invention are shown in the diagrams rather than the number, shape and Dimensional drawing, the type, quantity and proportion of each component can be changed arbitrarily during actual implementation, and the component layout type may also be more complicated.

In the prior art, there is a lack of protection methods for the surface of the wafer. Therefore, if the wafer is placed in the environment for a long time, the surface is prone to deposit particles, and the electrode surface is also prone to corrosion. As shown in Figure 1, the length of the wafer is After a period of time, some bad core particles appeared after testing, that is, the small black squares in the picture. Some of these defective core particles have particles attached to the surface (as shown in Figure 2), and some are corroded electrodes (as shown in Figure 3), which ultimately reduces the yield of the wafer.

The present invention protects the surface of the wafer by forming a protective layer on the surface of the wafer, and even in a bad environment, it can also play a good protective role, thereby reducing the storage cost and improving the stability of the wafer. At the same time, the protective layer is also easy to be decomposed and removed, and will not have adverse effects on the wafer.

Embodiment one

This embodiment provides a wafer protection method, as shown in Figure 4-6, the wafer protection method includes the following steps:

S1: providing a wafer 1, the upper surface of the wafer 1 has a plurality of electrodes;

S2: Apply a protection solution evenly on the upper surface of the wafer 1, and the protection solution is cured to form a protection layer 2;

S3: When the protective layer 2 needs to be removed, irradiate the protective layer with ultraviolet rays to gradually decompose the protective layer 2 to facilitate peeling off.

Specifically, in step S2, the protective liquid can be coated on the upper surface of the wafer 1 by spin coating, the protective liquid flows out through the nozzle 3, and the wafer 1 is rotated during the coating process. At the same time, the nozzle 3 is translated from the center of the wafer 1 to the edge of the wafer 1 . Thus, the protective liquid can evenly cover the surface of the wafer 1 .

Further, the material of the protective layer 2 includes silicon dioxide and titanium dioxide.

Specifically, the protective layer 2 also includes some photosensitive materials, adhesives, etc., so that it can be decomposed after being irradiated by ultraviolet rays, so that it can be easily peeled off. The peeling can be done by hand tearing or cleaning. In addition, the protective layer 2 should be insulated to prevent damage to the wafer caused by static electricity. When irradiating the protective layer 2 with ultraviolet light, it should be ensured that the irradiation time is longer than 30 minutes, so that the protective layer 2 can be fully decomposed.

In addition, heating may also be used to decompose the protective layer 2 for easy peeling. The method of ultraviolet radiation or heating is adopted, and the operation is convenient and the process cost is low.

Further, as shown in Fig. 7 and Fig. 8, the protective layer 2 is a one-layer or multi-layer structure.

Further, the thickness of the protective layer 2 is greater than 0.3mm.

Specifically, in order to ensure the insulating and protective effect of the protective layer 2, the thickness of the protective layer 2 should be ensured to be greater than 0.3 mm.

Through the above wafer protection method, a protective layer is formed on the surface of the wafer, which facilitates the long-term storage of the wafer without being affected by the storage environment, and the tiny dust and water vapor in the environment cannot contact the surface of the wafer. The layer has many advantages: fast solidification, good adhesion, dense film layer, hydrophobic and oleophobic, easy to remove, etc. Because the air, water vapor, etc. are isolated, the chemical solution (such as fluoride, chloride) remaining on the electrode surface is also avoided from chemical reaction during storage, so the electrode on the wafer surface is also protected, preventing the electrode from being corroded. grain failure problem. Using this method can reduce the requirements on the wafer storage environment, reduce the use pressure of the clean room, and the final yield rate will not be affected when the wafer is stored for a long time, and the reliability of the wafer is further improved.

Embodiment two

This embodiment provides a wafer protection structure. The wafer protection structure in this embodiment can be obtained by using the wafer protection method in Embodiment 1, but is not limited to the method in Embodiment 1. As shown in FIG. 5, the The wafer protection structures described above include:

Wafer 1, the upper surface of the wafer 1 has a plurality of electrodes;

A protective layer 2, the protective layer 2 covers the upper surface of the wafer 1 to isolate the surface of the wafer from the outside world, and the protective layer 2 will gradually decompose after being irradiated by ultraviolet rays or heated to facilitate peeling off.

Further, the material of the protective layer includes silicon dioxide and titanium dioxide.

Specifically, the protective layer 2 also includes some photosensitive materials, adhesives, etc., so that it can be decomposed after being irradiated by ultraviolet rays, so that it can be easily peeled off. The peeling can be done by hand tearing or cleaning. In addition, the protective layer 2 should be insulated to prevent damage to the wafer caused by static electricity. When irradiating the protective layer 2 with ultraviolet light, it should be ensured that the irradiation time is longer than 30 minutes, so that the protective layer 2 can be fully decomposed. In addition, heating may also be used to decompose the protective layer 2 for easy peeling. The method of ultraviolet radiation or heating is adopted, and the operation is convenient and the process cost is low.

Further, the protective layer 2 is formed on the upper surface of the wafer 1 by a spin coating method.

Further, the thickness of the protective layer is greater than 0.3 mm.

Specifically, in order to ensure the insulating and protective effect of the protective layer 2, the thickness of the protective layer 2 should be ensured to be greater than 0.3 mm.

Further, as shown in Fig. 7 and Fig. 8, the protective layer has a one-layer or multi-layer structure.

The wafer protection structure has a protective layer formed on the surface of the wafer, which facilitates the storage of the wafer for a long time without being affected by the storage environment. Tiny dust and water vapor in the environment cannot contact the surface of the wafer. At the same time, the protective layer has many advantages: fast solidification, good adhesion, dense film layer, hydrophobic and oleophobic, easy to remove, etc. Because the air, water vapor, etc. are isolated, the chemical solution (such as fluoride, chloride) remaining on the electrode surface is also avoided from chemical reaction during storage, so the electrode on the wafer surface is also protected, preventing the electrode from being corroded. grain failure problem. Using this method can reduce the requirements on the wafer storage environment, reduce the use pressure of the clean room, and the final yield rate will not be affected when the wafer is stored for a long time, and the reliability of the wafer is further improved.

The present invention has also designed a group of control experiments, the surface of the wafer part area is coated with the protective layer, and the rest of the surface is not treated, and then the treated wafer surface is soaked in a low-concentration fluorine solution (F solution ), the ratio of the fluorine solution is (200:1), to simulate the adverse environment when the wafer is stored in the actual situation. After 48 hours of immersion, the parts not covered by the protective layer showed serious surface corrosion, while the parts covered by the protective layer showed no damage. As shown in Figure 9, the upper part is the test result of the core particle covered with the protective layer, and the lower part is the test result of the core particle not covered with the protective layer, and the small black square represents the bad core particle, as shown in Figure 10, from the microscopic photo , the core electrode not covered by the protective layer is corroded.

To sum up, the present invention provides a wafer protection method and a wafer protection structure. By forming a protective layer on the surface of the wafer, it is convenient for the wafer to be stored for a long time without being affected by the storage environment. The protective layer has many advantages such as fast solidification, good adhesion, dense film layer, hydrophobic and oleophobic properties, and easy removal. At the same time, the electrodes on the surface of the wafer are also protected to avoid the problem of chip failure after the electrodes are corroded. Using this method can reduce the requirements on the wafer storage environment, reduce the use pressure of the clean room, and the final yield rate will not be affected when the wafer is stored for a long time. In addition, the protective layer can be decomposed by ultraviolet irradiation or heating to facilitate peeling and removal, and the operation is convenient and the process cost is low.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (10)

1. A wafer protection structure, characterized in that the wafer protection structure comprises:

a wafer, the upper surface of which is provided with a plurality of electrodes;

and the protective layer covers the upper surface of the wafer so as to isolate the surface of the wafer from the outside, and the protective layer can be gradually decomposed after being irradiated by ultraviolet rays or heated so as to be convenient to strip.

2. The wafer protection structure of claim 1, wherein the protective layer is formed on the upper surface of the wafer by spin coating.

3. The wafer protection structure of claim 1, wherein the protective layer has a thickness greater than 0.3mm.

4. The wafer protection structure of claim 1, wherein the material of the protective layer comprises silicon dioxide, titanium dioxide.

5. The wafer protection structure of claim 1, wherein the protective layer is one or more layers.

6. The wafer protection method is characterized by comprising the following steps of:

s1: providing a wafer, wherein the upper surface of the wafer is provided with a plurality of electrodes;

s2: uniformly coating a protective liquid on the upper surface of the wafer, and forming a protective layer after the protective liquid is solidified;

s3: when the protective layer needs to be removed, ultraviolet rays are used for irradiating the protective layer, so that the protective layer is gradually decomposed to be conveniently stripped.

7. The wafer protection method according to claim 6, wherein in step S2, the protection liquid is coated on the upper surface of the wafer 1 by spin coating, the protection liquid flows out through a nozzle, and the nozzle is translated from the center of the wafer to the edge of the wafer while the wafer is rotated during the coating process.

8. The wafer protection method of claim 6, wherein the protective layer has a thickness greater than 0.3mm.

9. The method of claim 6, wherein the protective layer is one or more layers.

10. The method of claim 6, wherein the material of the protective layer comprises silicon dioxide, titanium dioxide.

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