CN116394155A - Polishing head, final polishing equipment and final polishing method - Google Patents

Abstract

The present disclosure relates to a polishing head, a final polishing apparatus and a final polishing method, the polishing head comprising: a holding module having opposing first and second surfaces and for holding a silicon wafer to be polished at the first surface; And the temperature control ring, which is arranged at the second surface of the holding module and is arranged so that when the silicon wafer is held at the first surface, the central axis of the temperature control ring coincides with the central axis of the silicon wafer, so as to pass through the temperature control ring. A temperature control fluid is passed through the ring to make the temperature of the edge of the silicon wafer lower than that of the center of the silicon wafer during the polishing process. Through the polishing head, the final polishing equipment and the final polishing method of the present disclosure, the improvement of the flatness of the surface of the silicon wafer is realized.

Description

Polishing head, final polishing equipment and final polishing method

technical field

The present disclosure relates to the technical field of semiconductor processing and manufacturing, and in particular, to a polishing head, a final polishing device and a final polishing method.

Background technique

With the continuous development of semiconductor technology, the requirements for flatness, which is an important evaluation factor of silicon wafer quality, are getting higher and higher. Generally, improvement in flatness can be achieved by means of a double-side polishing process and a final polishing process in sequence.

In the final polishing process in which only the front side of the silicon wafer is polished, the silicon wafer is brought into face-to-face contact with the polishing pad by, for example, a polishing head with adsorption function, so that the rotating polishing pad can act on the surface of the silicon wafer, which is also in rotation, for example. The front side, so as to realize the polishing of the front side of the silicon wafer.

However, in the polishing process, the polishing fluid tends to move to the edge of the silicon wafer due to the centrifugal force generated by the rotation of the silicon wafer after contacting the silicon wafer and easily accumulates at this edge, while the polishing fluid is on the edge of the silicon wafer. The agglomeration in turn results in a greater amount of polishing being applied to the edge of the wafer compared to the center of the wafer, thereby making the edge of the wafer thinner compared to the center of the wafer and thus deteriorating the flatness of the wafer surface. In addition, when the silicon wafer is in contact with the polishing pad, the polishing pad will undergo a certain degree of compression deformation in the contact area, and this deformation will exert a greater effect on the outer edge of the silicon wafer near the chamfer, thereby relatively increasing the Polishing of the edge of the wafer, which also or further leads to a thinner thickness of the edge of the wafer compared to the center of the wafer and thus a deterioration of the flatness of the wafer surface.

Contents of the invention

This section provides a general summary of the disclosure, rather than a comprehensive disclosure of the full scope or all features of the disclosure.

The purpose of the present disclosure is to provide a polishing head capable of reducing the degree of polishing on the edge of a silicon wafer.

In order to achieve the above object, according to an aspect of the present disclosure, a polishing head is provided, which includes:

a holding module having opposite first and second surfaces and for holding the silicon wafer to be polished at the first surface; and

A temperature control ring, which is arranged at the second surface of the holding module and arranged such that the central axis of the temperature control ring coincides with the central axis of the silicon wafer when the silicon wafer is held at the first surface, for passing through the temperature control ring A temperature-controlling fluid is passed through the middle so that the temperature at the edge of the silicon wafer can be lower than that at the center of the silicon wafer during the polishing process.

In the above polishing head, the temperature control ring may be provided at a position of the second surface corresponding to an edge of the silicon wafer held at the first surface.

In the above polishing head, the temperature control ring may be a plurality of concentric rings capable of temperature control independently of each other.

In the above polishing head, the temperature control ring may be made of ceramic material.

In the above polishing head, the temperature control ring may be an integral annular part integrated into the second surface of the holding module.

In the above polishing head, the temperature control fluid may be cooling air, cooling water or cooling oil.

In the above polishing head, the temperature of the temperature control ring can be controlled by adjusting the temperature and/or flow rate of the temperature control fluid.

In the above polishing head, the holding module may be made of plastic material or ceramic material.

According to another aspect of the present disclosure, there is provided a final polishing apparatus comprising a polishing head according to any one of the preceding paragraphs.

According to yet another aspect of the present disclosure, there is provided a final polishing method performed using the final polishing apparatus according to the preceding paragraph, the final polishing method comprising:

During the polishing process, the temperature at the edge of the silicon wafer is lower than that at the center of the silicon wafer by passing a temperature control fluid into the temperature control ring.

According to the present disclosure, by setting the temperature control ring and making it and the silicon wafers respectively arranged on the two opposite surfaces of the holding module, and the central axis of which coincides with the central axis of the silicon wafer when being held, the temperature control ring can pass through the The temperature control fluid is injected so that the temperature of the edge of the silicon wafer is lower than that of the center of the silicon wafer during the polishing process, so that the temperature of the polishing liquid acting on the edge of the silicon wafer is lower than that of the polishing liquid acting on the center of the silicon wafer , thereby relatively reducing the polishing ability of the polishing liquid acting on the edge of the silicon wafer, so that the polishing degree of the edge of the silicon wafer is reduced, thereby reducing the difference between the polishing degree of the edge of the silicon wafer and the center of the silicon wafer, Thereby improving the flatness of the silicon wafer surface.

The above-mentioned features and advantages and other features and advantages of the present disclosure will be more apparent through the following detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings.

Description of drawings

1 is a plan view of a polishing head according to an embodiment of the present disclosure;

2 is a top view of a temperature control ring according to an embodiment of the present disclosure; and

3 is a top view of a temperature control ring according to another embodiment of the present disclosure.

Detailed ways

The present disclosure will be described in detail below by means of exemplary embodiments with reference to the accompanying drawings. It should be noted that the following detailed description of the present disclosure is for the purpose of illustration only, and by no means limits the present disclosure.

As mentioned before, during the polishing process, both the polishing pad and the silicon wafer will rotate, for example, in the same direction. Therefore, after the polishing liquid contacts the silicon wafer, it will tend to flow toward the silicon wafer due to the centrifugal force generated by the rotation of the silicon wafer. The edge of the wafer moves and tends to gather at this edge, resulting in a greater degree of polishing at the edge of the wafer than at the center of the wafer; in addition, the polishing pad will be placed on the edge of the wafer due to plastic deformation when in contact with the wafer. Applying greater action near the outer edge of the chamfer also causes the edge of the wafer to be polished more than the center of the wafer, thereby deteriorating the flatness of the wafer surface.

In order to solve the above problems, it is necessary to eliminate or at least reduce the difference between the degree of polishing at the edge of the silicon wafer and the degree of polishing at the center of the silicon wafer.

To this end, according to an aspect of the present disclosure, a polishing head 1 is proposed, referring to FIGS. 1 to 3 , which includes:

holding module 11, which has opposite first surface 111 and second surface 112, and is used to hold silicon wafer 10 to be polished at first surface 111; and

The temperature control ring 12 is arranged on the second surface 112 of the holding module 11 and is arranged such that the central axis of the temperature control ring 12 coincides with the central axis of the silicon wafer 10 when the silicon wafer 10 is held on the first surface 111, so that It is used to make the temperature of the edge of the silicon wafer 10 lower than the temperature of the center of the silicon wafer 10 during the polishing process by passing a temperature control fluid into the temperature control ring 12 .

Specifically, as shown in FIG. 1 , the polishing head 1 may include a head body 13, a rotary drive member 14 connected to one end of the head body 13, a holding module 11 connected to the other end of the head body 13, and Together with the holding module 11 there is an assembly module 15 for holding the silicon wafer 10 to be polished.

When polishing, the rotary drive member 14 will drive the head body 13 to rotate to drive the holding module 11 and the silicon wafer 10 it holds to rotate, so that the polishing head 1 presses the silicon wafer 10 on the rotating surface arranged under the polishing head 1. When on a polishing pad (not shown), the polishing of the silicon wafer 10 is achieved through the polishing pad and the polishing liquid distributed thereon.

In the embodiment of the present disclosure, the temperature control ring 12 and the silicon chip 10 are respectively arranged on two opposite surfaces of the holding module 11, that is, the first surface 111 and the second surface 112 (shown as opposite outer surfaces in FIG. 1 ). surface and inner surface), so that when the temperature control fluid is introduced into the temperature control ring 12 which itself is arranged at the second surface 112, the temperature control fluid will change the temperature of the second surface 112 of the holding module 11 through the temperature control ring 12. The temperature of the position corresponding to the temperature control ring 12, and thus change the temperature of the position corresponding to the above-mentioned position of the first surface 111, and then change the temperature of the part of the silicon wafer 10 held on the first surface 111 corresponding to the above-mentioned position . Moreover, the central axis of the temperature control ring 12 is set to coincide with the central axis of the silicon wafer 10 when it is held, for example, when it is adsorbed more specifically. The zone applies a temperature change effect.

In this way, the temperature control ring 12 can be set to reduce the temperature of the edge of the silicon wafer 10, or increase the temperature of the center of the silicon wafer 10, or reduce the temperature of the edge and the center of the silicon wafer 10 simultaneously but make the temperature of the edge Drop more, or increase the temperature of the edge and the center of the silicon wafer 10 at the same time but make the temperature of the center rise more, etc. to make the temperature of the edge of the silicon wafer lower than the temperature of the center of the silicon wafer.

In this case, due to the contact of the polishing liquid with the silicon wafer in the polishing process, the temperature of the polishing liquid acting on the edge of the silicon wafer 10 will also be lower than the temperature of the polishing liquid acting on the center of the silicon wafer 10, which will be relatively Reduce the polishing capability of the polishing liquid acting on the edge of the silicon wafer 10 as much as possible, so that the degree of polishing of the edge of the silicon wafer 10 is relatively reduced, thereby reducing the difference between the degree of polishing of the edge of the silicon wafer and the center of the silicon wafer , thereby improving the flatness of the silicon wafer surface.

As shown in Figures 1 and 2, the temperature control ring 12 has a fluid inlet 121 and a fluid outlet 122, and the fluid inlet 121 and the fluid outlet 122 are respectively connected to a fluid inlet pipe 121' and a fluid outlet pipe 122' (in Figure 1, The fluid outlet pipe 122' is invisible because it is covered by the fluid inlet pipe 121'), and the temperature control fluid supply and recovery unit supplies the temperature control fluid to the temperature control ring 12 through the fluid inlet pipe 121', and passes through the fluid outlet pipe 122 'Recover the temperature control fluid from the temperature control ring 12.

As mentioned before, the temperature control ring 12 can be arranged to reduce the temperature of the edge of the silicon wafer 10, so that the temperature control ring 12 can be arranged on the second surface 112 corresponding to the edge of the silicon wafer 10 held at the first surface. position, and can reduce the temperature of the temperature control ring 12 and thereby reduce the temperature of the edge of the silicon wafer 10 by passing a temperature control fluid with a lower temperature therein, thereby making the temperature of the edge of the silicon wafer lower than that of the silicon wafer. The temperature of the center of the sheet.

Similarly, when the temperature control ring 12 is arranged to increase the temperature of the center of the silicon wafer 10, it may be arranged at a position corresponding to the center of the silicon wafer held at the first surface on the second surface 112, and may Raise the temperature of the temperature control ring 12 and thus increase the temperature of the center of the silicon wafer 10 by passing a higher temperature control fluid therein, thereby making the temperature of the edge of the silicon wafer lower than that of the center of the silicon wafer temperature. Since other similar situations can be easily understood, details will not be repeated here.

In an embodiment of the present disclosure, the temperature control ring 12 may be a plurality of concentric rings capable of temperature control independently of each other.

As exemplarily shown in FIG. 3 , a plurality of concentric rings each have their own fluid inlets and fluid outlets (both shown in dotted circles) and are not connected to each other, thereby achieving temperature control independently of each other.

In this case, a plurality of concentric rings correspond to a plurality of annular regions centered on the center of the silicon wafer 10, and by arranging these multiple concentric rings to be able to control the temperature independently of each other, the temperature of the silicon wafer 10 can be improved. Multiple annular zones are temperature controlled independently of each other. For example, a relatively lower temperature is applied at the more polished annular region of the silicon wafer, while no temperature control is applied, or a relatively higher temperature is applied at the less polished annular region. Thus, more precise and flexible control of the temperature of the silicon wafer 10 can be achieved, thereby better improving the overall flatness of the silicon wafer.

In an embodiment of the present disclosure, the temperature control ring 12 can be made of ceramic material, which can reduce metal contamination in silicon wafer manufacturing.

It is conceivable that the temperature control ring 12 may be a separate component relative to the holding module 11 , fixed to the holding module 11 only by fixing elements.

However, it is also conceivable that the temperature control ring 12 may be an integral annular part integrated into the second surface 112 of the holding module 11 . For example, the temperature control ring 12 may be an annular portion embedded in the second surface 112 . In this case, the temperature can be better transferred from the temperature control fluid to the holding module 11 and thus to the silicon wafer 10, resulting in better temperature transfer and thus better control sensitivity and accuracy .

The temperature control fluid can be cooling air, cooling water or cooling oil. It can be understood that the temperature control fluid may also be any other suitable fluid capable of temperature control.

In an embodiment of the present disclosure, the temperature of the temperature control ring 12 can be controlled by adjusting the temperature and/or flow rate of the temperature control fluid.

It is conceivable that, in the case that the temperature control ring 12 is a plurality of concentric rings, each of the multiple concentric rings can be fed with different types of temperature control fluids, and for each ring, it is also possible to where the temperature and/or flow of a single type of temperature control fluid is used to control the temperature of the ring.

In an embodiment of the present disclosure, the holding module 11 may be made of plastic material or ceramic material. The plastic material can be polyvinylidene fluoride (PVDF), polyetheretherketone (PEEK) and the like.

According to another aspect of the present disclosure, there is also provided a final polishing device, which includes a polishing head 1 .

According to yet another aspect of the present disclosure, a final polishing method is also provided, the final polishing method is performed using the above-mentioned final polishing equipment, the final polishing method includes:

During the polishing process, the temperature at the edge of the silicon wafer is lower than that at the center of the silicon wafer by passing a temperature control fluid into the temperature control ring.

The above is only a specific implementation of the present disclosure, but the scope of protection of the present disclosure is not limited thereto, any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present disclosure, should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be determined by the protection scope of the claims.

Claims (10)

1. A polishing head, comprising:

a holding module having opposite first and second surfaces and for holding a silicon wafer to be polished at the first surface; and

a temperature control ring disposed at the second surface of the holding module and configured such that a central axis of the temperature control ring coincides with a central axis of the silicon wafer when the silicon wafer is held at the first surface for enabling a temperature of an edge of the silicon wafer to be lower than a temperature of a center of the silicon wafer during polishing by passing a temperature control fluid through the temperature control ring.

2. The polishing head as set forth in claim 1 wherein the temperature control ring is disposed at a position of the second surface corresponding to an edge of the silicon wafer held at the first surface.

3. A polishing head according to claim 1, wherein the temperature control ring is a plurality of concentric rings capable of controlling temperature independently of each other.

4. A polishing head according to any one of claims 1 to 3, wherein the temperature control ring is made of a ceramic material.

5. A polishing head according to any one of claims 1 to 3, wherein the temperature control ring is an integral annular portion integral to the second surface of the retaining module.

6. A polishing head according to any one of claims 1 to 3, wherein the temperature-controlling fluid is cooling air, cooling water or cooling oil.

7. A polishing head according to any one of claims 1 to 3, wherein the temperature of the temperature-control ring is controllable by adjusting the temperature and/or flow rate of the temperature-control fluid.

8. A polishing head according to any one of claims 1 to 3, wherein the holding module is made of a plastic material or a ceramic material.

9. A final polishing apparatus comprising the polishing head according to any one of claims 1 to 8.

10. A final-polishing method, characterized in that the final-polishing method is performed using the final-polishing apparatus according to claim 9, the final-polishing method comprising:

during the polishing process, the temperature of the edge of the silicon wafer is lower than the temperature of the center of the silicon wafer by introducing the temperature control fluid into the temperature control ring.

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