CN112864084A

CN112864084A - Wafer clamp

Info

Publication number: CN112864084A
Application number: CN202110259817.0A
Authority: CN
Inventors: 史蒂文·贺·汪; 林鹏鹏
Original assignee: Silicon Dense Core Plating Haining Semiconductor Technology Co ltd; Xinyang Guimi Shanghai Semiconductor Technology Co ltd
Current assignee: Silicon Dense Core Plating Haining Semiconductor Technology Co ltd; Xinyang Guimi Shanghai Semiconductor Technology Co ltd
Priority date: 2021-03-10
Filing date: 2021-03-10
Publication date: 2021-05-28

Abstract

The invention discloses a wafer clamp which is used for electroplating a wafer and comprises a supporting plate and a sealing element, wherein the supporting plate is used for supporting the wafer, the supporting plate can press the wafer on the sealing element, the wafer clamp also comprises a positioning element, the positioning element is provided with a limiting surface attached to the peripheral edge of the wafer, and the wafer is separated from the positioning element before the supporting plate presses the wafer on the sealing element. The wafer clamp places a wafer entering from the upper wafer opening on the positioning piece, the wafer and the sealing piece have good concentricity through the limiting surface attached to the peripheral side edge of the wafer, and then the wafer is pressed on the sealing piece after being transferred to the supporting plate through the relative motion of the positioning piece and the supporting plate so as to obtain better sealing effect and further obtain better electroplating uniformity.

Description

Wafer clamp

Technical Field

The invention relates to the field of wafer electroplating, in particular to a wafer clamp.

Background

A semiconductor plating machine is a device used in a chip manufacturing process for plating metal ions in a plating solution onto a wafer surface. The electroplating machine comprises a frame, an electroplating bath, a circulating system, a cleaning tank, an electroplating hanger and the like. Among them, the wafer holder in the electroplating hanger is the most important auxiliary tool for electroplating process, and it has direct influence on the distribution and working efficiency of the electroplating coating. In single-sided plating, the tightness of the plating rack is critical to protect the single-sided plating, and the tightness of the plating rack is closely related to the consistency of the sealed edge of the wafer. Once the concentricity of the wafer and the sealing element is insufficient or the angle is changed, the sealing performance is greatly reduced, the obtained electroplated layer is not uniform, better conduction uniformity cannot be obtained, and the performance of the wafer is affected.

Disclosure of Invention

The invention aims to solve the technical problems that in the prior art, the concentricity of a wafer and a sealing element is insufficient, an obtained electroplated layer is not uniform, and better conduction uniformity cannot be obtained, and provides a wafer clamp.

The invention solves the technical problems through the following technical scheme:

the utility model provides a wafer anchor clamps for the wafer is electroplated, wafer anchor clamps include layer board and sealing member, the layer board is used for bearing wafer, the layer board can with the wafer is pressed and is located on the sealing member, wafer anchor clamps still include the setting element, the setting element have with the spacing face of the side edge laminating of wafer week the layer board will the wafer is pressed and is located before the sealing member, the wafer with the setting element breaks away from mutually.

In the invention, by adopting the form, the wafer enters from the upper plate opening of the wafer clamp, the wafer and the sealing element have good concentricity through the limiting surface attached to the peripheral side edge of the wafer, and then the wafer is pressed in front of the sealing element under the driving of the supporting plate through the relative movement of the positioning element and the supporting plate, so that the positioning element is separated from the wafer, the positioning of the positioning element on the peripheral side of the wafer is prevented from influencing the normal sealing of the sealing element on the wafer, and the normal sealing effect is ensured.

Preferably, the positioning member further has a supporting surface for supporting the wafer, and the supporting surface is located below the limiting surface.

In the invention, the wafer is in a state of stable overall stress when being placed on the positioning piece by adopting the form.

Preferably, the supporting plate moves upward relative to the positioning member, and during the relative movement, the wafer is separated from the positioning member along the relative movement direction.

In the invention, by adopting the form, no matter the positioning piece supports the wafer or clamps the wafer, the wafer can be stably transferred to the supporting plate from the positioning piece without influencing the existing concentricity.

Preferably, when the wafer is separated from the positioning member, the positioning member moves outward along the radial direction of the wafer.

In the invention, the mode is adopted, so that the phenomenon that the wafer is not transferred smoothly or is displaced due to larger force for clamping the wafer is prevented, and the concentricity of the wafer and the sealing element is reduced.

Preferably, the upper end of the limiting surface extends to form a guide surface, and the guide surface is used for guiding the wafer to be attached to the limiting surface.

In the invention, the above form is adopted, so that when the wafer is placed into the positioning piece from the wafer loading opening, the wafer can be automatically guided into the space formed by the limiting surface within a certain error range.

Preferably, the guide surface is an arc surface curved outward.

In the invention, the guiding process is smoother and more convenient to operate by adopting the form.

Preferably, the positioning members are uniformly distributed along the circumferential direction of the wafer.

In the invention, the positioning piece is adopted to fix the wafer in all directions, so that the positioning effect is better.

Preferably, the number of the positioning pieces is at least three.

In the invention, the positioning piece can form a stable structure from three directions for positioning by adopting the form.

Preferably, the edge of the supporting plate is further provided with a clamping edge, the lower end of the clamping edge is provided with a bayonet, and the inner diameter of the bayonet is equal to the outer diameter of the wafer.

In the invention, the wafer can be just clamped at the inner side of the clamping edge after being exchanged from the positioning piece to the supporting plate by adopting the form, and displacement is avoided, so that better concentricity is kept.

Preferably, the inner diameter of the bayonet is smaller than or equal to that of the limiting surface, and an inclined surface inclined towards the outside is arranged above the bayonet.

In the invention, the wafer is more easily and stably exchanged to the supporting plate from the positioning piece by adopting the form through the guiding function of the inclined surface.

Preferably, the inner side of the sealing element is provided with a raised sealing lip which is in sealing fit with one side surface of the wafer facing the sealing element.

In the invention, by adopting the form and utilizing the characteristic that the height of the sealing lip is lower, the best sealing effect can be realized by applying certain pressure on the premise of meeting the concentricity requirement of the wafer and the tray.

Preferably, an avoiding area is formed on the supporting plate, and the avoiding area comprises a projection position of the positioning piece on the supporting plate.

In the invention, the positioning piece and the supporting plate do not interfere with each other in the moving process by adopting the form, and an additional moving mechanism is not required to be added, so that the integral stability is further ensured.

Preferably, the sealing member is fixed to an auxiliary positioning member, the auxiliary positioning member is detachably mounted on an auxiliary mounting member, and the auxiliary mounting member is formed on or fixed to the base.

In the invention, the sealing element is detachably connected to the base by adopting the form, so that the concentricity of the sealing element and the supporting plate is not changed in a working state, and better concentricity can be ensured even if the sealing element is remounted after being detached.

Preferably, a conductive member is further disposed inside the sealing member, the conductive member is used for conducting the wafer and the electrode, and the conductive member is fixed to the auxiliary positioning member.

In the invention, the conductive piece is arranged at the inner side of the sealing piece by adopting the form, the conduction of a circuit is realized in the electroplating process, the structure is simple, and the concentricity of the sealing piece and the supporting plate is not influenced.

Preferably, the auxiliary positioning part and the auxiliary mounting part are connected through a bolt.

In the invention, the auxiliary positioning piece and the auxiliary mounting piece are connected in a mode of higher precision and better stability by adopting the form.

Preferably, the positioning member is fixed to the base.

In the invention, the positioning piece and the sealing piece are directly or indirectly fixed on the base by adopting the form, so that the concentricity of the positioning piece and the sealing piece is ensured, and the positioning piece, the supporting plate and the sealing piece have good concentricity.

The positive progress effects of the invention are as follows: the wafer clamp places a wafer entering from the upper wafer opening on the positioning piece, the wafer and the sealing piece have good concentricity through the limiting surface attached to the peripheral side edge of the wafer, and then the wafer is pressed on the sealing piece after being transferred to the supporting plate through the relative motion of the positioning piece and the supporting plate so as to obtain better sealing effect and further obtain better electroplating uniformity.

Drawings

FIG. 1 is a schematic diagram of an internal structure of a wafer chuck according to an embodiment of the present invention.

Fig. 2 is an enlarged schematic view of the specific structures of the positioning member and the supporting plate according to the embodiment of the present invention.

Fig. 3 is an enlarged schematic view of a specific structure of the card edge in the embodiment of the present invention.

Figure 4 is a cross-sectional view of a wafer chuck in accordance with an embodiment of the present invention.

Fig. 5 is a schematic structural view of an auxiliary positioning member and an auxiliary mounting member according to an embodiment of the present invention.

Fig. 6 is a schematic structural diagram of a positioning element according to another embodiment of the present disclosure.

Description of reference numerals:

wafer clamp 100

Chip loading port 101

Wafer 200

Positioning piece 1

Limiting surface 11

Bearing surface 12

Guide surface 13

Pallet 2

Escape area 21

Sealing element 3

Sealing lip 31

Card edge 4

Bayonet 41

Bevel 42

Auxiliary positioning member 51

Auxiliary mounting 52

Base 6

Fixing ring 7

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.

As shown in fig. 1-4, the present embodiment provides a wafer chuck 100 for wafer plating, the wafer chuck 100 includes a supporting plate 2 and a sealing member 3, the supporting plate 2 is disposed on a base 6, and is used for supporting a wafer 200 and can be lifted and lowered relative to the base 6 under the driving of a driving unit (not shown). The sealing element 3 is arranged on the fixing ring 7, the fixing ring 7 is also arranged on the base 6, when the supporting plate 2 rises, the supporting plate 2 can drive the wafer 200 to rise and enable the wafer 200 to be pressed on the annular sealing element 3, the conducting ring is arranged inside the sealing element 3, and the edge part of the wafer 200, which is in lap joint with the conducting ring, is separated from the surface of the wafer 200 to be electroplated through the sealing element 3.

In this embodiment, as shown in fig. 1, the wafer fixture 100 further includes three positioning members 1, the positioning members 1 and the supporting plate 2 are both disposed on the base 6 of the wafer fixture 100, the three positioning members 1 are uniformly distributed around the supporting plate 2, and the positioning members 1 have limiting surfaces 11 attached to the peripheral edges of the wafer 200. Specifically, when the external mechanism places the wafer 200 on the wafer chuck 100, the wafer 200 is directly placed on the bearing surfaces 12 of the three positioning members 1, and the bearing surfaces 12 of the three positioning members 1 are located at the same height and are all higher than the surface 2a of the supporting plate 2 for bearing the wafer 200. Then the supporting plate 2 is driven by the driving unit to rise, the surface 2a of the supporting plate 2 contacts with the wafer 200 and continues to lift with the wafer 200, before the supporting plate 2 drives the wafer 200 to rise and presses the wafer 200 on the sealing element 3, the wafer 200 is separated from the positioning element 1, and the situation that the limiting surface 11 of the positioning element 1 prevents the wafer 200 from pressing on the sealing element 3 is avoided.

In this embodiment, the three positioning members 1 are completely fixed on the base 6, and therefore cannot move relative to the base 6, the sealing member 3 or the fixing ring 7, and the influence of the limiting surface 11 for positioning the side surface of the wafer 200 on the normal sealing of the sealing member 3 when the wafer 200 is pressed against the sealing member 3 is also completely avoided.

In this embodiment, the wafer 200 entering from the upper wafer opening 101 is first placed on the positioning member 1, and has a good concentricity with the sealing member 3 through the position-limiting surface 11 attached to the peripheral edge of the wafer 200, and then the wafer 200 is transferred to the surface 2a of the supporting plate 2 by the relative movement of the positioning member 1 and the supporting plate 2, and then pressed on the sealing member 3, so as to obtain a better sealing effect.

Specifically, in the electroplating process, the requirement on the sealing performance is high, and when the sealing effect reaches a certain degree, the electroplated layer can be ensured to be uniform. The uniformity of the electroplated layer determines the conductivity of the wafer 200, which is an important parameter. Therefore, in order to ensure the uniformity of the plating layer, the present embodiment adopts the form that the positioning member 1 is combined with the supporting plate 2, and the side limiting surface 11 is utilized to keep the wafer 200 and the sealing member 3 at a high concentricity, so as to obtain a better sealing effect.

As shown in fig. 1 to 4, the positioning member 1 further has a supporting surface 12 for supporting the wafer 200, and the supporting surface 12 is located below the limiting surface 11. The pallet 2 moves upward relative to the positioning member 1, and during the relative movement, the wafer 200 is separated from the positioning member 1 in the relative movement direction.

In this embodiment, the supporting surface 12 at the lower part of the positioning member 1 is utilized to make the wafer 200 be in a stable state when being placed in the positioning member 1, and when the positioning member 1 moves, the wafer 200 can be kept stable on the supporting surface 12 without moving.

This embodiment also provides another implementation: the positioning member 1 itself does not have a supporting surface 12, the wafer 200 is positioned by the limiting surface 11, and the supporting plate 2 supports the wafer 200 from below, when the wafer 200 is separated from the positioning member 1, the positioning member 1 moves outward along the radial direction of the wafer 200.

In this embodiment, the effect of bearing face 12 is for bearing wafer 200, if do not set up bearing face 12, can borrow the effect that layer board 2 played the bearing to fix wafer 200 through spacing face 11 on the setting element 1, play the effect of centre gripping, loosen again after stable. In order to prevent the wafer 200 from being transferred or displaced due to a large force for clamping the wafer 200, so that the concentricity of the wafer 200 and the sealing member 3 is reduced, when the wafer 200 is separated from the positioning member 1, the positioning member 1 moves outward in the radial direction of the wafer 200.

It should be understood that whether the positioning member 1 holds the wafer 200 or clamps the wafer 200, both embodiments of the present invention can smoothly transfer the wafer 200 from the positioning member 1 to the supporting plate 2 without affecting the existing concentricity.

As shown in fig. 1 to 4, the upper end of the limiting surface 11 extends to form a guiding surface 13, and the guiding surface 13 is an arc surface that is bent outward and used for guiding the wafer 200 to adhere to the limiting surface 11.

In this embodiment, the guiding surface 13 can automatically guide the wafer 200 into the space formed by the limiting surface 11 within a certain error range when the wafer 200 is placed into the positioning member 1 from the upper opening 101, and the arc-shaped guiding surface 13 bent outward can make the guiding process smoother and more convenient to operate.

Specifically, after the wafer 200 is placed from the upper wafer opening 101, the wafer contacts the guide surface 13 first, and then slides down along the guide surface 13 under the action of its own gravity to fall into the space surrounded by the limiting surface 11 and used for accommodating the wafer 200. This avoids the problem of jamming or misalignment that may be encountered when directly placing the wafer 200 from the wafer loading port 101 into the space for accommodating the wafer 200.

As shown in fig. 1-4, the positioning members 1 are uniformly distributed along the circumferential direction of the wafer 200, and the number of the positioning members 1 is at least three.

Specifically, in the embodiment, three positioning members 1 are adopted, and the three positioning members 1 are uniformly distributed along the circumferential direction of the wafer 200, so that the wafer 200 is fixed from each direction, and the positioning effect is better. Because the least three positioning pieces 1 can form a relatively stable structure, the positioning pieces 1 can form a stable structure to be positioned in the form that the at least three positioning pieces 1 are uniformly distributed.

As shown in fig. 6, this embodiment also provides another implementation: all the positioning members 1 are an integral body and have a plurality of relatively independent limiting surfaces 11, and the limiting surfaces 11 are independently arranged and uniformly distributed along the circumferential direction of the wafer 200. The lower surface of the positioning member 1 may be integrally fixed to the base 6.

In the present embodiment, the plurality of limiting surfaces 11 cooperate to perform the function of precise positioning. In order to avoid that the accuracy of a positioning member 1 is inaccurate and the accuracy of other positioning members 1 is affected due to the fact that the positioning members 1 are separately arranged, all the positioning members 1 are connected into a whole.

It should be understood that the spacer 1 can be connected using a connector, or that all of the spacers 1 can be integrally formed during manufacture. The former is more favorable to dismouting and regulation, is convenient for finely tune, and the latter is more favorable to whole change, and the precision is higher. Those skilled in the art can adopt corresponding schemes according to different requirements.

As shown in fig. 1-4, the edge of the pallet 2 is further provided with a clamping edge 4, the lower end of the clamping edge 4 is provided with a bayonet 41, and the inner diameter of the bayonet 41 is equal to the outer diameter of the wafer 200. The inner diameter of the bayonet 41 is equal to or less than the inner diameter of the stopper surface 11, and a slope 42 inclined outward is provided above the bayonet 41.

In the embodiment, when the wafer 200 is exchanged from the positioning member 1 to the pallet 2, the wafer can be exactly clamped from the inner side of the limiting surface 11 to the inner side of the bayonet 41, and in the process, the wafer does not laterally displace, so that good concentricity is maintained. Further, the wafer 200 is more easily and stably exchanged from the positioning member 1 to the pallet 2 by the guiding action of the inclined surface 42 above the bayonet 41.

Specifically, without relying on the chuck edge 4, the wafer 200 may bump due to impact at the moment of collision with the pallet 2, resulting in a decrease in concentricity. In this embodiment, the clamping edge 4 disposed at the edge of the pallet 2 can generate the effect of gradually transferring the wafer 200 from the positioning member 1 to the pallet 2, which is more stable in comparison.

As shown in fig. 1 to 4, the sealing member 3 has a raised sealing lip 31 on the inner side, and the sealing lip 31 is in sealing engagement with the surface of the wafer 200 facing the sealing member 3.

In this embodiment, the sealing lip 31 having a low height projecting from the sealing material 3 is used to apply a predetermined pressure from the tray 2 side on the premise of satisfying the concentricity requirement between the wafer 200 and the tray 2, thereby achieving the sealing effect.

Specifically, in the present embodiment, the wafer 200 is pressed by the blade 2 against the sealing member 3, and the sealing lip 31 on the sealing member 3 seals the wafer 200 toward the sealing member 3 and is spaced from the outside. During the plating process, the sealing member 3 separates the plating solution from the inner surface of the wafer 200, and the plating solution contacts the outer surface of the wafer 200 to form a charge path "electrode-wafer 200-plating solution-electrode" via the conductive member. When the concentricity of the wafer 200 and the sealing element 3 is good, the sealing effect in each direction can meet the sealing requirement of electroplating, and the electroplated layer can be more uniform.

As shown in fig. 1 to 4, an avoidance area 21 is formed on the pallet 2, and the avoidance area 21 includes a projection position of the positioning member 1 on the pallet 2.

In this embodiment, since the movement tracks of the pallet 2 and the positioning element 1 are in the same direction and interference is very likely to occur in the process of relative movement, an avoidance area 21 is formed on the pallet 2, so that the positioning element 1 and the pallet 2 do not interfere with each other in the movement process. Therefore, an additional movement mechanism is not needed to be added, and the overall stability is further ensured.

Specifically, on the premise that the pallet 2 can satisfy the supporting condition, a space can be reserved as the avoidance area 21 when the pallet 2 is designed and manufactured. It will be appreciated by the person skilled in the art that the avoidance machined on the pallet 2 according to the actual risk of interference after the position of the positioning element 1 has been determined also belongs to an implementation of the avoidance zone 21.

As shown in fig. 1 to 5, the sealing member 3 is disposed on the fixing ring 7, the auxiliary positioning member 51 is fixed on the fixing ring 7 for positioning and installation of the fixing ring 7 after being detached from the base 6, the auxiliary positioning member 51 can be positioned in the hole of the auxiliary mounting member 52 by inserting and positioning, and the auxiliary mounting member 52 is formed on or fixed on the base 6.

In the present embodiment, the auxiliary positioning member 51 and the auxiliary mounting member 52 are used to detach the sealing member 3 and the fixing ring 7 from the base 6, and the positioning and mounting accuracy after detachment is improved, so that after the fixing ring 7 is detached and the sealing member 3 and the conductive member are replaced or debugged, when the fixing ring 7 is mounted on the base 6 again, the concentricity between the sealing member 3 and the pallet 2 in the operating state is not changed, and even if the fixing ring is mounted again after detachment, a good concentricity can be ensured. Meanwhile, the positioning pin is inserted and fixed, so that the positioning difficulty can be reduced, and the time spent on mounting the fixing ring 7 again after being detached is reduced.

Specifically, the sealing member 3 is located above the base 6, the sealing member 3 is connected to the auxiliary positioning member 51 through the fixing ring 7, the auxiliary positioning member 51 is detachably connected to the auxiliary mounting member 52, and the auxiliary mounting member 52 is formed on the base 6, so that a relatively stable connection structure is formed between the sealing member 3 and the base 6. Since the sealing member 3 needs to be removed for cleaning or replacement in some cases, the mounting position of the sealing member 3 is relatively fixed by removing and mounting the auxiliary positioning member 51 and the auxiliary mounting member 52, so that the position accuracy of the sealing member 3 is improved, and the concentricity of the sealing member 3 and the wafer 200 is ensured.

In this embodiment, the auxiliary positioning member 51 and the auxiliary mounting member 52 are connected by a latch, which provides a connection manner between the auxiliary positioning member 51 and the auxiliary mounting member 52 with high precision and good stability.

It should be understood that the detachable connection between the two can be realized by a conventional detachable connection or an installation manner, and in this embodiment, the latch connection is only selected from a plurality of manners which are convenient and firm. After a plurality of times of disassembly and assembly, the error accumulated by the repeated disassembly and assembly is eliminated by accurate measurement and adjustment.

In this embodiment, the sealing member 3 further has a conductive member (not shown) inside. The conductive member is used for conducting the wafer 200 and the electrode, and the conductive member is fixed on the auxiliary positioning member 51. Through setting up the electrically conductive piece in sealing member 3 inboard, realize switching on of circuit in electroplating process, simple structure, and do not influence the concentricity of sealing member 3 and layer board 2.

As shown in fig. 1-5, the positioning member 1 is fixed to the base 6.

In this embodiment, the positioning member 1 and the sealing member 3 are directly or indirectly fixed on the base 6, so that the concentricity of the positioning member 1 and the sealing member 3 can be ensured, and the positioning member 1, the supporting plate 2 and the sealing member 3 all have good concentricity.

Specifically, when a special condition is met or the positioning member 1 needs to be disassembled, the positioning member 1 is fixed on the base 6, and the sealing member 3 is also fixed on the base 6, so that the positioning member 1 and the sealing member have a relatively fixed positional relationship. This reduces positional deviation due to repeated attachment and detachment, and maintains good concentricity between the retainer 1 and the packing 3 even when the attachment and detachment are performed a plurality of times.

While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that this is by way of example only, and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention, and these changes and modifications are within the scope of the invention.

Claims

1. The utility model provides a wafer anchor clamps for the wafer is electroplated, wafer anchor clamps include layer board and sealing member, the layer board is used for bearing wafer, the layer board can with the wafer is pressed and is located on the sealing member, its characterized in that, wafer anchor clamps still include the setting element, the setting element have with the spacing face of the edge laminating of wafer week side the layer board will the wafer is pressed and is located before the sealing member, the wafer with the setting element breaks away from mutually.

2. The wafer chuck as claimed in claim 1, wherein the positioning member further has a supporting surface for supporting the wafer, and the supporting surface is located below the limiting surface.

3. The wafer holder of claim 2, wherein the blade moves upward relative to the positioning member, and during the relative movement, the wafer disengages from the positioning member in the direction of the relative movement.

4. The wafer holder of claim 1, wherein the blade moves upward relative to the positioning member, and during the relative movement, the wafer disengages from the positioning member in the direction of the relative movement.

5. The wafer chuck as claimed in claim 4, wherein the positioning member moves outward in a radial direction of the wafer when the wafer is disengaged from the positioning member.

6. The wafer holder of claim 1, wherein the upper end of the retaining surface extends to form a guide surface for guiding the wafer to engage with the retaining surface.

7. The wafer holder of claim 6, wherein the guide surface is an outwardly curved arcuate surface.

8. The wafer holder of claim 1, wherein the positioning members are uniformly distributed along the circumferential direction of the wafer.

9. The wafer holder of claim 8, wherein the number of the positioning members is at least three.

10. The wafer clamp of claim 1, wherein the edge of the supporting plate is further provided with a clamping edge, the lower end of the clamping edge is provided with a bayonet, and the inner diameter of the bayonet is equal to the outer diameter of the wafer.

11. The wafer holder of claim 10, wherein the inner diameter of the bayonet is smaller than or equal to that of the limiting surface, and an inclined surface inclined to the outside is arranged above the bayonet.

12. The wafer holder of claim 1, wherein the seal has a raised sealing lip on an inner side thereof, the sealing lip sealingly engaging a surface of the wafer facing the seal.

13. The wafer clamp of claim 1, wherein an avoidance area is formed on the supporting plate, and the avoidance area comprises a projection position of the positioning member on the supporting plate.

14. The wafer holder of claim 1, wherein the seal is secured to an auxiliary positioning member, the auxiliary positioning member being removably mounted to an auxiliary mounting member formed on or secured to the base.

15. The wafer chuck as claimed in claim 14, wherein the sealing member further has a conductive member inside, the conductive member is used for conducting the wafer and the electrode, and the conductive member is fixed to the auxiliary positioning member.

16. The wafer holder of claim 15, wherein the auxiliary positioning member is connected to the auxiliary mounting member by a pin.

17. The wafer holder of claim 16, wherein the positioning member is secured to the base.