A wafer-level mask and electroplating process

Abstract

A wafer-level mask plate larger in size than a wafer, having a device pattern area, an annular protection area surrounding the device pattern area and smaller in diameter than the wafer, and a support area provided outside the annular protection area for fixing the mask plate on the exposure light path of a lithography machine; the electroplating process using this mask plate is as follows: spin-coat a negative or positive photoresist on the surface of the wafer, after edge cleaning, use the wafer-level mask plate for exposure and development to form an annular photoresist layer smaller in diameter than the wafer and surrounding the device pattern layer under the annular protection area; transfer the wafer to an electroplating machine tool, after the sealing compression ring of the electroplating machine tool is pressed against the annular photoresist layer, introduce electroplating solution into the device pattern layer, after electroplating is completed, drain the electroplating solution and remove the photoresist layer to obtain a wafer with a device electroplating layer. This process utilizes the tight engagement between the annular photoresist layer formed by exposure and development of the wafer-level mask plate and the sealing compression ring, effectively avoiding the influence of electroplating solution leakage from the edge of the wafer on subsequent processes and improving the product yield.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more particularly, to a wafer-level mask and an electroplating process using the same. Background Art

[0002] In the semiconductor manufacturing process, the electroplating process is a common method for metal deposition. Currently, the mainstream electroplating machine presses the wafer surface through the wafer edge seal ring, and the contact probe conducts current to the wafer within the seal ring. The wafer edge removes the wafer photoresist by wafer edge cleaning or wafer edge exposure to leave a detection position for the detection probe. In the actual production process, because the accuracy of removing the wafer edge photoresist by the methods of edge cleaning and traditional wafer edge exposure is ±0.1 mm to 0.3 mm, and the pressing position of the electroplating equipment sealing device itself also has mechanical errors, which will cause the pressing position of the wafer to press on the photoresist pattern area. The uneven photoresist in the pattern area will cause the sealing device of the electroplating equipment to be not tightly pressed, resulting in the electroplating solution leaking to the edge cleaning area, and the detection probe contacting the electroplating solution to conduct electricity and issue an alarm. The unsealed pressing of the electroplating equipment sealing device causes the electroplating solution to leak out from the edge of the wafer, affecting the subsequent process, resulting in a decrease in product yield. In addition, the detection probe will be electroplated with metal, causing poor contact in subsequent use and unable to effectively detect whether the next wafer leaks electroplating solution. Summary of the Invention

[0003] An object of the present invention is to provide a wafer-level mask having a size larger than the wafer to be exposed, which has a device pattern area, a ring-shaped protection area surrounding the device pattern area and having a diameter smaller than the wafer to be exposed, and a support area provided outside the ring-shaped protection area for fixing the mask on the exposure light path of the lithography machine. The ring-shaped protection area is used to form a ring-shaped photoresist layer below it after exposure and development. The electroplating process using this mask is as follows: First, a negative or positive photoresist is spin-coated on the surface of the wafer so that the diameter of the photoresist layer is smaller than that of the wafer. Then, the wafer-level mask is used for exposure and development to obtain a wafer having a device pattern layer and a ring-shaped photoresist layer surrounding the device pattern layer and having a diameter smaller than the wafer. Next, the wafer is transferred to the electroplating machine. After the sealing press ring of the electroplating machine presses against the ring-shaped photoresist layer, the electroplating solution is introduced into the device pattern layer. After energizing for a period of time, the electroplating solution is discharged and the photoresist is removed to obtain a wafer having a device electroplating layer. By using the ring-shaped protection area of the wafer-level mask, the ring-shaped photoresist layer formed by exposure and development is tightly joined with the sealing press ring, effectively avoiding the influence of the electroplating solution leaking from the edge of the wafer on the subsequent process, resulting in a decrease in product yield, and the detection probe will not be electroplated with metal, causing poor contact in subsequent use, and can effectively detect whether the next wafer leaks electroplating solution, extending the service life of the electroplating machine.

[0004] Embodiments of the present invention are implemented as follows:

[0005] On one hand, the present invention provides a wafer-level mask, which is larger in size than the wafer to be exposed. The wafer-level mask has a device pattern area, a circular protection area that surrounds the device pattern area and has a diameter smaller than that of the wafer, and a support area provided on the periphery of the circular protection area. Among them, the device pattern area is used for exposure and development to form a device pattern, the circular protection area is used for forming a circular photoresist layer below it after exposure and development, and the support area is used to fix the mask on the exposure light path of the lithography machine.

[0006] Optionally, the circular protection area is a light-transmissive type, which is used to transmit the exposure light source and cure the negative photoresist below it, and a negative circular photoresist layer is formed after development.

[0007] Optionally, the circular protection area is a light-shielding type, which is used to block the exposure light source to avoid photochemical reactions of the positive photoresist below it, and a positive circular photoresist layer is formed after development.

[0008] Optionally, the width of the circular protection area is 2 mm to 4 mm.

[0009] On the other hand, the present invention provides an electroplating process for a wafer-level mask, including:

[0010] Step 1: Spin-coat a negative photoresist on the surface of the wafer, and wash the edge by 0.5 mm to 2 mm to make the diameter of the negative photoresist layer smaller than that of the wafer;

[0011] Step 2: Use a wafer-level mask fixed on the exposure light path of the lithography machine, which has a device pattern area and a light-transmissive circular protection area, for exposure and development to obtain a wafer with a device pattern layer and a negative circular photoresist layer that surrounds the device pattern layer and has a diameter smaller than that of the wafer;

[0012] Step 3: Transfer the wafer to an electroplating machine table. After the sealing compression ring of the electroplating machine table is pressed against the negative circular photoresist layer, electroplating solution is introduced into the device pattern layer;

[0013] Step 4: After electroplating is completed, discharge the electroplating solution and remove the negative photoresist to obtain a wafer with a device electroplating layer.

[0014] On the other hand, the present invention provides an electroplating process for a wafer-level mask, including:

[0015] Step 1: Spin-coat a positive photoresist on the surface of the wafer, and wash the edge by 0.5 mm to 2 mm to make the diameter of the positive photoresist layer smaller than that of the wafer;

[0016] Step 2: Use a wafer-level mask fixed on the exposure light path of the lithography machine, which has a device pattern area and a light-shielding circular protection area, for exposure and development to obtain a wafer with a device pattern layer and a positive circular photoresist layer that surrounds the device pattern layer and has a diameter smaller than that of the wafer;

[0017] Step 3: Transfer the wafer to the electroplating machine stage. After the sealing compression ring of the electroplating machine stage is pressed against the positive annular photoresist layer, electroplating solution is introduced into the device pattern layer.

[0018] Step 4: After electroplating is completed, the electroplating solution is drained and the positive photoresist is removed to obtain a wafer with a device electroplating layer.

[0019] Optionally, after Step 3, it further includes: the detection probe of the electroplating machine stage abuts against the edge cleaning area of the wafer to detect whether the electroplating solution leaks out of the sealing compression ring.

[0020] Optionally, the device electroplating layer is a metal interconnection layer or a metal electrode layer, and the material is any one of Cu, Ni, or Sn / Ag.

[0021] Optionally, the electroplating time is 5 min to 30 min.

[0022] Optionally, the wafer material is any one of SOI, Si, GaAs, AlN, ceramic, sapphire, SiC, LiTaO3, or LiNbO3.

[0023] The beneficial effects of the present invention include:

[0024] By using the annular protection area designed by the wafer-level mask, while forming the device pattern area by one-time exposure and development, an annular photoresist layer that surrounds the device pattern area and has a diameter smaller than the wafer is formed. The annular photoresist layer has a soft texture. When the sealing compression ring is pressed down, if it is slightly inclined, the annular photoresist layer can be deformed by extrusion to achieve surface-to-surface fitting. The annular photoresist layer can be tightly joined with the sealing compression ring to achieve sealing, effectively avoiding the influence of the electroplating solution leaking from the edge of the wafer on the subsequent process, resulting in a decrease in product yield. And the detection probe will not be electroplated with metal, resulting in poor contact during subsequent use, and can effectively detect whether the electroplating solution leaks from the next wafer, extending the service life of the electroplating machine stage.

[0025] Preferably, the width of the annular protection area is 2 mm to 4 mm, so that the width of the annular photoresist layer after exposure and development is greater than the lower surface of the sealing compression ring of the electroplating machine stage. When the sealing compression ring is pressed down, even if there is a slight alignment error, it can be completely pressed against the annular photoresist ring, making the joint surface between the annular photoresist layer and the sealing compression ring large enough to further avoid the electroplating solution leaking from the edge of the wafer and improve the product yield. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.

[0027] Figure 1 Schematic diagram of a wafer - level mask provided by an embodiment of the present invention;

[0028] Figure 2 Schematic diagram of electroplating on an electroplating machine provided by an embodiment of the present invention;

[0029] Figure 3 One of the schematic diagrams of the electroplating process state provided by an embodiment of the present invention;

[0030] Figure 4 Two of the schematic diagrams of the electroplating process state provided by an embodiment of the present invention;

[0031] Figure 5 Three of the schematic diagrams of the electroplating process state provided by an embodiment of the present invention;

[0032] Figure 6 Four of the schematic diagrams of the electroplating process state provided by an embodiment of the present invention.

[0033] Icon: 1 - wafer; 2 - annular photoresist layer; 3 - device pattern layer; 4 - electroplated layer; 5 - wafer - level mask; 51 - annular protection area; 52 - device pattern area; 6 - sealing compression ring; 7 - electroplating solution; 8 - detection probe. Detailed implementation manners

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings or the positional relationship that the invention product is usually in during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention. In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0037] Please refer to Figures 1-6 , this embodiment provides an electroplating process for a wafer-level mask, which includes:

[0038] Step 1: Spin-coat a positive or negative photoresist on the surface of the wafer 1 to be electroplated, with a thickness of 5 μm to 110 μm, and trim the edge by 0.5 mm to 2 mm, so that the diameter of the photoresist layer is smaller than that of the wafer 1;

[0039] Step 2: Use the support area (usually located at the edge position, which can fix the mask) of the wafer-level mask 5 to fix the wafer-level mask 5 on the exposure light path of a proximity exposure lithography machine. The wafer-level mask 5 has a device pattern area 52 and an annular protection area 51 located in the middle area and surrounding the device pattern area 52. The outermost diameter of the annular protection area 51 is smaller than that of the wafer 1 to be exposed. Preferably, the outermost diameter of the annular protection area 51 is equal to the diameter of the photoresist layer after trimming. Expose and develop the wafer 1 to obtain a wafer 1 with a device pattern layer 3 and an annular photoresist layer 2. The width of the annular protection area 51 is 2 mm to 4 mm. The annular protection area 51 is designed to match the positive or negative photoresist. Specifically: the annular protection area 51 is a light-transmitting type, which is used to transmit the exposure light source and cure the negative photoresist below it, and a negative annular photoresist layer is formed after development; or, the annular protection area 51 is a light-shielding type, which is used to block the exposure light source to prevent the positive photoresist below it from undergoing a photochemical reaction, and a positive annular photoresist layer is formed after development;

[0040] Step 3: Transfer the wafer 1 to an electroplating machine table. After the sealing compression ring 6 of the electroplating machine table is aligned and pressed against the annular photoresist layer 2, electroplating solution 7 is introduced into the area where the device pattern layer 3 is located until it is higher than the annular photoresist layer 2. The contact probe (not shown in the figure) of the electroplating machine table extends into the electroplating solution 7, and the detection probe 8 of the electroplating machine table abuts against the trimmed area of the wafer 1 to detect whether the electroplating solution 7 leaks out of the sealing compression ring 6 during the electroplating process. The electroplating solution 7 can be Cu, Ni or Sn / Ag, and the electroplating time is 5 min to 30 min. Specifically, it is Cu - 20 min, Ni - 5 min, Sn / Ag - 30 min;

[0041] Step 4: After electroplating is completed, drain the electroplating solution 7 and remove the photoresist to obtain a wafer 1 with a device electroplated layer 4. The device electroplated layer 4 is a metal interconnection layer or a metal electrode layer, and the material is Cu, Ni or Sn / Ag.

[0042] In this electroplating process, the annular protection area 51 designed by the wafer-level mask 5 is used to form an annular photoresist layer 2 that surrounds the device pattern layer 3 and has a diameter smaller than the wafer 1 while forming the device pattern layer 3 through one-time exposure and development. The annular photoresist layer 2 is relatively soft. When the sealing pressure ring 6 is pressed down, even if it is slightly tilted, the annular photoresist layer 2 can be deformed by extrusion to achieve surface-to-surface fitting. The annular photoresist layer 2 can be tightly joined with the sealing pressure ring 6 to achieve sealing, effectively avoiding the influence of the electroplating solution leaking from the edge of the wafer 1 on the subsequent processes, resulting in a decrease in product yield. Moreover, the detection probe 8 will not be electroplated with metal, causing poor contact during subsequent use, and it can effectively detect whether the electroplating solution leaks from the next wafer, extending the service life of the electroplating machine.

[0043] The width of the annular protection area 51 is designed to be 2 mm to 4 mm, so that the width of the annular photoresist layer 2 after exposure and development is greater than the lower surface of the sealing pressure ring 6 of the electroplating machine. When the sealing pressure ring 6 is pressed down, even if there is a slight alignment error, it can be completely pressed onto the annular photoresist layer 2, making the joint surface between the annular photoresist layer 2 and the sealing pressure ring 6 large enough to further avoid the electroplating solution leaking from the edge of the wafer 1 and improve the product yield.

[0044] The above are only optional embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0045] In addition, it should be noted that in the above specific embodiments, the various specific technical features described can be combined in any suitable way without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

Claims

1. An electroplating process using a wafer-level mask, characterized in that, It includes the following steps: Step 1: Spin-coat a negative photoresist on the surface of the wafer, and wash the edge by 0.5 mm to 2 mm to make the diameter of the negative photoresist layer smaller than that of the wafer. Step 2: Use a wafer-level mask for exposure and development to obtain a wafer with a device pattern layer and a negative annular photoresist layer that surrounds the device pattern layer and has a diameter smaller than that of the wafer. The wafer-level mask has a device pattern area, an annular protection area that surrounds the device pattern area and has a diameter smaller than that of the wafer, and a support area provided on the periphery of the annular protection area. Among them, the device pattern area is used for exposure and development to form a device pattern, the annular protection area is used to form an annular photoresist layer below it after exposure and development, and the support area is used to fix the mask on the exposure light path of the lithography machine. The annular protection area is of a light-transmitting type and is used to transmit the exposure light source and cure the negative photoresist below it to form a negative annular photoresist layer after development. Step 3: Transfer the wafer to the electroplating machine table. After the sealing compression ring of the electroplating machine table presses against the negative annular photoresist layer, introduce the electroplating solution into the device pattern layer. Step 4: After electroplating is completed, drain the electroplating solution and remove the negative photoresist to obtain a wafer with a device electroplated layer.

2. The electroplating process of the wafer-level mask as described in claim 1, characterized in that, After Step 3, it further includes: The detection probe of the electroplating machine table abuts against the washed edge area of the wafer to detect whether the electroplating solution leaks out of the sealing compression ring.

3. The electroplating process of the wafer-level mask as described in claim 1, characterized in that: The device electroplated layer is a metal interconnection layer or a metal electrode layer, and the material is any one of Cu, Ni, or Sn / Ag.

4. The electroplating process of the wafer-level mask as described in claim 1, characterized in that: The electroplating time is 5 minutes to 30 minutes.

5. The electroplating process of the wafer-level mask as described in claim 1, characterized in that: The wafer material is any one of SOI, Si, GaAs, AlN, ceramic, sapphire, SiC, LiTaO3, or LiNbO3.

6. An electroplating process using a wafer-level mask, characterized in that, It includes the following steps: Step 1: Spin-coat a positive photoresist on the surface of the wafer, and wash the edge by 0.5 mm to 2 mm to make the diameter of the positive photoresist layer smaller than that of the wafer. Step 2: Use a wafer-level mask for exposure and development to obtain a wafer with a device pattern layer and a positive annular photoresist layer that surrounds the device pattern layer and has a diameter smaller than that of the wafer. The wafer-level mask has a device pattern area, an annular protection area that surrounds the device pattern area and has a diameter smaller than that of the wafer, and a support area provided on the periphery of the annular protection area. Among them, the device pattern area is used for exposure and development to form a device pattern, the annular protection area is used to form an annular photoresist layer below it after exposure and development, and the support area is used to fix the mask on the exposure light path of the lithography machine. The annular protection area is of a light-shielding type and is used to block the exposure light source to prevent the positive photoresist below it from undergoing a photochemical reaction to form a positive annular photoresist layer after development. Step 3: Transfer the wafer to the electroplating machine table. After the sealing compression ring of the electroplating machine table presses against the positive annular photoresist layer, introduce the electroplating solution into the device pattern layer. Step 4: After electroplating is completed, drain the electroplating solution and remove the positive photoresist to obtain a wafer with a device electroplated layer.

7. The electroplating process of the wafer-level mask as described in claim 6, characterized in that, After Step 3, it further includes: The detection probe of the electroplating machine table abuts against the washed edge area of the wafer to detect whether the electroplating solution leaks out of the sealing compression ring.

8. The electroplating process of the wafer-level mask as described in claim 6, characterized in that: The device electroplated layer is a metal interconnection layer or a metal electrode layer, and the material is any one of Cu, Ni, or Sn / Ag.

9. The electroplating process of the wafer-level mask as described in claim 6, characterized in that: The electroplating time is 5 minutes to 30 minutes.

10. The electroplating process of the wafer-level mask as described in claim 6, characterized in that: The wafer material is any one of SOI, Si, GaAs, AlN, ceramic, sapphire, SiC, LiTaO3 or LiNbO3.

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