TWI447845B - Chuck table and method for unloading wafer using the same - Google Patents

Description

Vacuum platform and wafer unloading method

The invention relates to a vacuum platform and a wafer unloading method, in particular to a vacuum platform and a wafer unloading method capable of forming a local positive pressure between a vacuum portion and a wafer.

In recent years, with the rapid development of applications, semiconductor wafers have gradually required thinning. Ultra-thin semiconductor wafers are fragile and prone to distortion and become extremely difficult to use.

In general, a semiconductor wafer is processed by forming a plurality of elements on its surface, and the semiconductor wafer is ground or polished from the back side in a back grinding process to form a desired thickness. Thereafter, each element is cut in the back grinding treatment step. After the back grinding process is performed on the back surface of the semiconductor wafer, the semiconductor wafer is placed on a chuck table, and the protective tape is peeled off.

After the tape is peeled off, the contact surface of the vacuum platform and the wafer generates a negative pressure due to vacuum adsorption. It is necessary to blow air from a vacuum platform for air blow, thereby separating the wafer from the vacuum platform. Since the pressure between the contact surface of the vacuum platform and the wafer is drastically changed, high stress is generated, and as a result, the thinned semiconductor wafer is liable to be bent and broken.

In summary, how to reduce the problem of bending and breakage of a thinned wafer during unloading is an urgent task.

The invention provides a vacuum platform and a wafer unloading method, which can form a local positive pressure between the vacuum platform and the wafer, thereby reducing the bending and breakage of the wafer.

According to an embodiment of the invention, a vacuum platform includes a vacuum portion for generating a pressure difference to attract a wafer, and the vacuum portion has a plurality of lifting members. Each lifting member has a plurality of holes connected to a pump for providing a vacuum attractive force to attract the wafer, wherein each lifting member is vertically movable to lift the wafer from the vacuum portion, each lifting member It can be moved in the direction of the vertical wafer and blown by the holes to form a local positive pressure between the vacuum and the wafer.

According to another embodiment of the present invention, a wafer unloading method includes the steps of: attracting a wafer by a vacuum platform, wherein the vacuum platform includes a vacuum portion for generating a pressure difference to attract the wafer, and the vacuum portion has a plurality of lifting members, each lifting member having a plurality of holes connected to a pump to provide vacuum attraction to attract the wafer; and each lifting member sequentially moving toward the vertical wafer and being blown by the holes The local positive pressure is formed between the vacuum portion and the wafer.

The above and other aspects, features and advantages of the present invention will become more apparent from the description of the appended claims.

Please refer to FIGS. 1a to 1d, which are schematic diagrams showing a vacuum platform and a wafer unloading method according to an embodiment of the present invention. 2 is a schematic view showing a vacuum platform in accordance with a preferred embodiment of the present invention. Referring to FIG. 1a and FIG. 2, the vacuum platform 1 includes a vacuum portion 2 for generating a pressure difference to attract a wafer 3. The vacuum portion 2 has a plurality of lifting members 211, 212, 213, and each lifting member has A plurality of holes 22 are connected to a pump (not shown) for providing vacuum attraction to attract the wafer 3.

A protective tape 32 (BG tape) is attached to the wafer 3 during the wafer mounting process to protect the front side of the wafer 3 from contamination or damage during the grinding process. After the wafer 3 grinding and pasting process is completed, the protective tape 32 can be peeled off. In the process of peeling off the protective tape 32, the wafer 3 is adhered to the vacuum portion 2 of the vacuum stage 1 by the dicing tape 31. The wafer 3 can define the relative position of the wafer 3 to the vacuum platform 1 by a wafer ring 33 and avoid the collision between the wrinkles of the tape cutting and the crystal grains.

Referring to FIG. 2, the vacuum portion 2 is circular and disposed opposite to the wafer 3. The three lifting members 211, 212, 213 form a concentric circle, that is, the lifting member 211 has a circular shape, and the lifting members 212 and 213 are annular.

However, the shape of the lifting member is not limited thereto. For example, the shape of the lifting member may be a rectangular shape or the like.

Referring to FIG. 1b, when the wafer 3 is unloaded from the vacuum portion 2, each lifting member can be sequentially moved toward the vertical wafer 3, and blown by the holes 22, forming a local portion between the vacuum portion 2 and the wafer 3. Positive pressure. Since only a partial positive pressure is formed between the vacuum portion 2 and the wafer 3, that is, only a partial vacuum is broken, the stress on the wafer 3 is small, and the bending and breakage are reduced. Further, in this embodiment, since the vacuum portion 2 and the wafer 3 are centered at the vacuum, the degree of bending is small and is less likely to be broken. Among them, the gas blown by the hole 22 is generally nitrogen gas, which can be pressurized by a pump (not shown).

It should be noted that the general relative position of the vacuum platform 1 and the wafer 3 is as shown in the figure; that is, the vacuum platform 1 and the wafer 3 are horizontally disposed. In addition, it is considered that the vacuum platform 1 and the wafer 3 may also be vertically disposed, and the moving direction of the lifting member 211 is still the vertical direction of the wafer 3.

Referring to FIG. 1c, as described above, when the wafer 3 is unloaded from the vacuum portion 2, each lifting member can be sequentially moved in the direction of the vertical wafer 3, and is blown by the holes 22, between the vacuum portion 2 and the wafer 3. A local positive pressure is formed. Therefore, the elevating member 212 then sinks downward toward the wafer 3, and is blown by the holes 22 toward the wafer 3, and a partial positive pressure is formed between the vacuum portion 2 and the wafer 3, and the vacuum portion 2 and the wafer 3 are formed. Partially breaking the vacuum between. In this embodiment, each of the lifting members is moved from the inside to the outside in a direction perpendicular to the wafer 3. However, it will be understood that other sequences, such as from the outside, are also possible. As shown, first, the elevating member 211 is moved in the direction of the vertical wafer 3.

Referring to FIG. 1d, as described above, the lifting member 213 can be lowered and blown by the hole 22, a partial positive pressure is formed between the vacuum portion 2 and the wafer 3, and a partial vacuum is broken between the vacuum portion 2 and the wafer 3. After the wafer 3 is unloaded from the vacuum platform 1, the wafer 3 can be handled by a robot arm or other handling device.

In summary, the present invention provides a plurality of lifting members on a vacuum platform, and the lifting members can be sequentially moved, and the air is blown from the holes toward the wafer to form a local positive pressure between the vacuum portion and the wafer. The stress on the wafer during the unloading process is small, and the bending and breakage are reduced.

The embodiments described above are only intended to illustrate the technical idea and the features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention. That is, the equivalent variations or modifications made by the spirit of the present invention should still be included in the scope of the present invention.

1. . . Vacuum platform

2. . . Vacuum department

211-213. . . Lifting member

twenty two. . . Hole

3. . . Wafer

31. . . Cutting tape

32. . . Protective tape

33. . . Patch ring

1a to 1d are schematic views showing a vacuum platform and a wafer unloading method according to an embodiment of the present invention.

2 is a schematic view showing a vacuum platform in accordance with a preferred embodiment of the present invention.

211-213. . . Lifting member

3. . . Wafer

31. . . Cutting tape

33. . . Patch ring

Claims (10)

A vacuum platform includes: a vacuum portion for generating a pressure difference to attract a wafer; and a plurality of lifting members located at the vacuum portion, wherein each of the lifting members has a plurality of holes connected to a pump Providing a vacuum attraction to attract the wafer; and each of the lifting members can be sequentially moved in a direction perpendicular to the wafer and blown by the holes toward the wafer to make the vacuum portion and the crystal A local positive pressure is formed between the circles to unload the wafer from the vacuum. The vacuum platform of claim 1, wherein the vacuum portion is circular, which is disposed opposite the wafer. The vacuum platform of claim 2, wherein the lifting members form a concentric circle. A vacuum platform according to claim 3, wherein the vacuum portion comprises three lifting members. The vacuum platform of claim 1, wherein the lifting members are rectangular. The vacuum platform of claim 1, wherein the wafer is disposed in the vacuum portion with a dicing tape. A wafer unloading method includes the steps of: attracting a wafer by a vacuum platform, wherein the vacuum platform comprises: a vacuum portion for generating a pressure difference to attract the wafer, the vacuum portion having a plurality of lifting members, Each of the lifting members has a plurality of holes connected to a pump to provide a vacuum attraction to attract the wafer; and each of the lifting members sequentially moves in a direction perpendicular to the wafer, and The holes are blown to form a local positive pressure between the vacuum portion and the wafer. The wafer unloading method of claim 7, wherein the lifting members form a concentric circle. The wafer unloading method of claim 8, wherein each of the lifting members is sequentially moved from the inside to the outside in a direction perpendicular to the wafer. The wafer unloading method of claim 7, wherein each of the lifting members sequentially moves toward the wafer in a direction away from the wafer, and the holes are blown toward the wafer.