TW201351516A - Structure and manufacturing method of electroless nickel bump of wafer diepad - Google Patents

Abstract

A structure and manufacturing method of electroless nickel bump of wafer diepad comprises: a wafer with a surface and a plurality of diepads mounted at the surface and a protection layer formed on the surface with a plurality of openings provided to expose the diepads; a plurality of catalyst layers formed on the surface of diepads by nickeling process and constituted with nickel, a plurality of electrodless nickel bumps formed with appropriate height on the surface of diepad catalyst layer by electrodeless nickel way and constituted with electroless nickel, and a plurality of outer protection layers with each of outer protection layer contains at least a protection layer constituted by dipping in one material selected from the family of immersion gold (IG) layer or immersion silver (ES) layer and these outer protection layers are formed on the surfaces of these bumps by utilizing the process selected from a family of IG process or ES process under the state of photoresistor installed. The hardness of these electrodeless nickel bumps can be improved and lowered via the forming of these outer protection layers avoid the difficulties processes in the post process due to excessive surface hardness of the electroless nickel bump.

Description

Wafer pad nickel-plated bump structure and manufacturing method thereof

The present invention relates to a nickel-plated bump structure for a wafer pad and a method for fabricating the same, and more particularly to a catalyst layer on the surface of the pads by using an electroless nickel method in a state where a photoresist is provided. The surface is respectively formed with a bump of appropriate height and made of electroless nickel, and then one of the groups selected from the group of gold processing and silver processing is used to form an outer layer on the upper surface of each bump. So that the outer sheath comprises at least one protective layer selected from the group consisting of an immersion gold (IG) layer and a silver (ES) layer, thereby improving and reducing the hardness of the nickel-plated bump And achieve the effect of process simplification and production cost reduction.

In the technical field related to the connection of semiconductor wafers or wafers (such as pad bumps), packages or related processes, there are various prior art, such as: Republic of China M397591, M352128, M412460, M412576, M410659 I306638, I320588, I255538, I459362, I253733, I273651, I288447, I295498, I241658, I259572, I472371, I242866, I269461, I329917, I282132, I328266, I284949; and US Patent Nos. US 8,030,767, US 7,981,725, US 7,969,003 US 7,960,214, US 7,847,414, US 7,749,806, US 7,651,886, US 7,538,020, US 7,750,467, US 7,364,944, US 7,019,406, US 6,507,120, US 7,999,387, US 7,993,967, US 7,868,470, US7 , 868, 449, US 7, 972, 902, US 7,960, 825, US 7, 952, 187, US 7,944, 043, US 7, 934, 313, US 7, 906, 855 et al. It is known from the above-mentioned technical contents of these prior art that these patents are almost all minor improvements in their technical fields. In other words, in the technical field related to the connection, packaging, or related processes of semiconductor wafers or wafers, the space for technological development has been quite limited, and thus in the field of the crowded art (in the field of the crowded art) If there is a slight improvement in technology, it must be regarded as "progressive" and still be able to approve patents.

The nickel-plated bump structure of the wafer pad of the present invention and the manufacturing process thereof have the advantages of simplifying the process and reducing the manufacturing cost in the field of limited development of the structure of the bump structure and the process thereof, and further capable of An invention that effectively improves and reduces the hardness of the formed nickel-plated bumps to meet the requirements of the subsequent process in the post-process. Since the prior art described above must form a metal layer on the pads by an Under Bump Metallization (UBM) process before forming the bumps, the metal plating or printing silver paste is used in the prior art. The bumps are formed on the metal layers of the pads. Therefore, the processes of the prior art are not only costly but also difficult to manufacture, which relatively complicates the process and reduces the yield, and the bumps Need to use more precious metal materials.

In addition, in the case of the bump formed by the silver paste, the hardness of the silver paste bump is larger, that is, the hardness can be changed from softer to harder, and can be adjusted by using baking conditions; however, the nickel-plated bump is used. In general, the hardness range of the nickel-plated bumps is small, that is, the surface hardness of the nickel-plated bumps is too large and cannot be adjusted by baking conditions, which is disadvantageous for the subsequent process of the post-process.

It can be seen from the above that the structures and processes of the prior art are difficult to meet the requirements in actual use. Therefore, in the technical field of the bump structure of the wafer pad and the manufacturing process thereof, a process simplification, a reduction in manufacturing cost, and a convexity are developed and designed. The surface hardness of the block conforms to the bump structure required by the subsequent process of the post-process, and it does have its necessity.

The main object of the present invention is to provide a bump structure of a wafer pad and a manufacturing method thereof, which are provided with a catalyst on the surface of the wafer pads by using an electroless nickel method in a state where a photoresist is provided. The surface of the layer respectively forms a bump of appropriate height and composed of electroless nickel, and then one of the groups selected from the group of gold processing and silver processing is used to form an external protection on the upper surface of each of the bumps. a layer, wherein the outer sheath comprises at least one protective layer selected from the group consisting of an immersion gold (IG) layer and a silver (ES) layer, thereby improving and reducing the nickel-plated bump Hardness, and achieve the effect of process simplification and production cost reduction.

In order to achieve the above object, a preferred embodiment of the bump structure of the wafer pad of the present invention comprises: a wafer comprising a surface, a plurality of pads disposed on the surface, and a protective layer formed on the surface a plurality of openings are provided for correspondingly exposing the pads; a plurality of catalyst layers are formed by zincation to form a catalyst layer made of zinc on the surfaces of the pads; Electroless nickl bumps are formed by using an electroless nickel method to form an appropriate height on the surface of the catalyst layer on the surface of the pads and made of electroless nickel. Bump And a plurality of outer sheaths, wherein each outer sheath comprises at least one protective layer composed of a material selected from the group consisting of an immersion gold (IG) layer and a silver (ES) layer, and the outer sheath is provided In the state of photoresist, one of the groups selected from the group of gold processing and silver processing is separately formed on the upper surfaces of the bumps. The formation of the outer sheath is used to improve and reduce the hardness of the nickel-plated bumps, so as to avoid excessive surface hardness of the nickel-plated bumps, which is not conducive to the subsequent process of the post-process.

In order to achieve the above object, a preferred embodiment of the method for manufacturing a bump of a wafer pad of the present invention comprises the steps of: providing a wafer having a surface, a plurality of pads disposed on the surface, and a a first protective layer is formed on the surface and is provided with a plurality of openings for correspondingly exposing the pads; a photoresist layer is formed on the first protective layer and the photoresist layer is patterned to form a plurality of openings for Corresponding to exposing a portion of the first protective layer around the pads and the pads; and then using a zincation process to form a catalyst layer made of zinc on the surface of the pads; An electroless nickl method for forming a bump formed of electroless nickel in the openings; and using one of a group selected from the group consisting of a gold process and a silver process while still providing a photoresist a process for forming an outer cover layer on each of the upper surfaces of the bumps, wherein each outer cover layer comprises at least one protective layer selected from the group consisting of an immersion gold (IG) layer and a silver (ES) layer a material; and removing the photoresist layer to reveal An outer protective layer, the first protective layer other than below the bumps and the bumps.

In order to make the present invention more clear and detailed, the structure, technical features and processes of the present invention are described in detail below with reference to the following figures: Referring to Figures 1-3, respectively, the wafer bonding pads of the present invention are plated. A schematic cross-sectional view of a different embodiment of a nickel bump structure. The nickel-plated bump structure 1 of the wafer pad of the present invention comprises: a wafer 10, a plurality of catalyst layers 20, a plurality of electroless nickl bumps 30, and a plurality of outer sheath layers 40.

The wafer 10 includes: a surface 11; a plurality of pads 12 disposed on the surface 11; and a first protective layer 13 formed on the surface 11 and provided with a plurality of openings 14 for corresponding The pads 12 are exposed. The wafer 10 is generally provided by a wafer manufacturer. The layout of the plurality of pads 12 on the surface 11 is not limited, and can be arranged in various arrays according to customer needs. The first protective layer 13 is generally made of a nitride material.

The plurality of catalyst layers 20 are subjected to a zincation treatment to form a catalyst layer 20 made of zinc on the surfaces of the pads 12. The catalyst layer 20 is a zincation layer formed by zincation, and its main function is to connect the die pads 12, and at the same time, when performing the subsequent electroless metal method. The dielectric layer is deposited to form a bump 30 of electroless nickel. In this embodiment, the catalyst layer 20 is a zinc salt aqueous solution having a concentration by weight of 15-30%, and a 10-30 second (sec) time at a solution temperature of 20-35 ° C to form a zinc. Catalyst layer.

The plurality of bumps 30 are made of an electroless metal of electroless nickel (Electroless Nickel) and are provided with a photoresist to form a suitable height on the surface of the catalyst layers 20 on the surface of the pads 12. A bump 30, which is made of electroless nickel, is also referred to herein as an electroless nickl bump 30. In this embodiment, the thickness of the bumps 30 is formed. It is produced by electroless (chemical plating) nickel deposition. In the nickel salt material used in the embodiment, the nickel material of the phosphoric acid series such as nickel phosphate is the best, and the nickel phosphate has the function of self-catalytic reaction, and can effectively improve the nickel-plated convex formed by the deposition of electroless nickel. The thickness (height) of the block 30 is such as to achieve the thickness of the bumps 30 required for the design. In this embodiment, the bumps 30 made of electroless nickel are made of a nickel salt aqueous solution having a concentration of 4-6.5 g/L (g/L), and the elapsed time is 30-75 at a solution temperature of 75-100 ° C. Minutes (min) are formed by deposition.

The outer protective layer 40 is formed on one surface of the bumps by using one of the group selected from the gold processing and the silver processing process in a state in which the patterned photoresist is provided, and each outer protective layer 40 is separately formed on the upper surface of the bumps. The layer comprises at least one protective layer comprised of a material selected from the group consisting of an immersion gold (IG) layer and a silver (ES) layer. Therefore, the outer sheath 40 of the present invention comprises the following three different structural types: a first structural type: as shown in FIG. 1, the outer sheath 40 comprises an inner layer of immersion gold (IG) layer. 40a and a thick gold (EG) layer 40b in the outer layer, which is formed by a gold forming process to form an immersion gold (IG) layer 40a on the outer surface of the nickel-plated bump 30, and then the gold immersion ( A thick gold (EG) layer 40b is further formed on the outer surface of the IG) layer 40a; in the first structural form, the nickel-plated bump 30 has a thickness of about 2-14 micrometers (μm), the dip The gold (IG) layer 40a has a thickness of about 0.01 to 0.05 micrometers (μm), and the thick gold (EG) layer 40b has a thickness of about 0.5 to 2.0 micrometers (μm).

The second structural type: as shown in FIG. 2, the outer sheath 40 is a silver (ES) layer 40c which is formed by a silver forming process to form a surface on the outer surface of the nickel-plated bump layer. a silver (ES) layer; in the second structural form, the nickel-plated bump 30 has a thickness of about 2 to 14 micrometers (μm), and the silver (ES) layer 40c has a thickness of about 0.5 to 2.0. Micron (μm).

The third structural type: as shown in FIG. 3, the outer sheath 40 includes one The inner layer of the silver (ES) layer 40d and the outer layer of the gold (IG) layer 40e are formed by a silver forming process to form a silver (ES) on the outer surface of the nickel-plated bump 30. The layer 40d is further subjected to a gold plating process to form an immersion gold (IG) layer 40e on the outer surface of the silver (ES) layer 40d. In the third structural form, the nickel-plated bumps 30 have a thickness of about 2 to 14 micrometers (μm), and the silver (ES) layer 40d has a thickness of about 0.5 to 2.0 micrometers (μm). The immersion gold (IG) layer 40e has a thickness of about 0.01 to 0.05 micrometers (μm).

4A-4F, which is a cross-sectional view of an embodiment of the method for fabricating the bump structure shown in FIGS. 1-3; the bump process of the present embodiment includes the following steps: Referring to FIG. 4A, a wafer is provided. 10, the wafer 10 has a surface 11; a plurality of pads 12 are disposed on the surface 11; and a first protective layer 13 is formed on the surface 11 and is provided with a plurality of openings 14 for correspondingly exposing the pads 12 . Wherein the distance between the openings is less than or equal to 16 μm (micrometer, 10 ^-6 m); and referring to FIG. 4B, a photoresist layer is further formed on the first protective layer and the photoresist layer is patterned. The first photoresist layer 13 having a plurality of openings 51 in the patterned photoresist layer 50 for respectively exposing a portion of each of the pads 12 and the pads 12; and referring to FIG. 4C, reusing zincation Zincating to form a catalyst layer 20 made of zinc on the surface of the pads 12; in the embodiment, the catalyst layer 20 is a zinc salt aqueous solution having a concentration by weight of 15-30%. The elapsed time is 10 to 60 seconds (sec) at a solution temperature of 20 to 35 ° C to form a catalyst layer 20 composed of zinc.

Referring to FIG. 4D again, an electroless nickel method is used to form a nickel-plated bump 30 made of electroless nickel in the openings 51; in the embodiment, the nickel-plated bumps are formed. The thickness of 30 is greater than or equal to 6 μm (micron, 10 ^-6 m) (ie thickness) 6 μm). Since the nickel-plated bumps 30 of the present embodiment are formed in a state in which the patterned photoresist layer 50 is provided, the height of the nickel-plated bumps 30 of the present embodiment is generally higher than that of the photoresists. The height of the bump formed in the state of the layer; in the embodiment, the nickel-plated bumps 30 are made of a nickel salt aqueous solution having a concentration of 4-6.5 g/L (g/L) at a solution temperature of 75. A time of 30-75 minutes (min) was taken at -100 ° C to form a deposit. In this embodiment, the nickel-plated bumps 30 have a thickness of 2-15 μm (micrometers, 10 ^-6 m).

Referring to FIG. 4E again, in the state where the patterned photoresist layer 50 is still provided, as shown in FIG. 4D, one of the groups selected from the group of gold processing and silver processing is used to perform the plating. An outer sheath 40 is formed on the upper surface of the nickel bump 30, wherein each outer sheath 40 comprises at least one protective layer, as shown in FIG. 1 40a, 40b or 40c as shown in FIG. 2 or as shown in FIG. 40d, 40e, wherein the protective layer is selected from a material selected from the group consisting of an immersion gold (IG) layer and a silver (ES) layer; that is, the outer sheath 40 of the present invention comprises the first Three different structural types, such as the third one, are the first structural type shown in FIG. 1, the second structural type shown in FIG. 2, and the third type shown in FIG. Structure type. The outer sheath 40 shown in FIG. 4E is illustrated by way of example and not limitation in the first structural form shown in FIG.

Referring to FIG. 4F (in the present embodiment, FIG. 4F is the same as FIG. 1), the photoresist layer 50 is removed to expose the outer protective layer 40, the nickel-plated bumps 30, and the like. The first protective layer 13 other than under the bumps is a process for completing the nickel-plated bump structure 1 of the wafer pad of the present invention.

The above are only the preferred embodiments of the present invention, and are merely illustrative and not restrictive. It will be apparent to those skilled in the art that many changes, modifications, and equivalents may be made without departing from the spirit and scope of the invention.

1‧‧‧ Nickel-plated bump structure

10‧‧‧ wafer

11‧‧‧ surface

12‧‧‧ solder pads

13‧‧‧Protective layer

14‧‧‧ openings

20‧‧‧ catalyst layer

30‧‧‧ Nickel-plated bumps

40‧‧‧ outer sheath

40a‧‧‧ immersion gold (IG) layer

40b‧‧‧ thick gold (EG) layer

40c‧‧‧ Silver (ES) layer

40d‧‧‧chemical silver (ES) layer

40e‧‧‧ immersion gold (IG) layer

50‧‧‧ photoresist layer

51‧‧‧ openings

1 is a schematic cross-sectional view showing an embodiment of a nickel-plated bump structure of a wafer pad of the present invention.

2 is a schematic cross-sectional view showing another embodiment of a nickel-plated bump structure of a wafer pad of the present invention.

3 is a schematic cross-sectional view showing still another embodiment of the nickel-plated bump structure of the wafer pad of the present invention.

4A-4F are schematic cross-sectional views showing an embodiment of a process for forming a nickel-plated bump structure of a wafer pad of the present invention.

1‧‧‧ Nickel-plated bump structure

10‧‧‧ wafer

11‧‧‧ surface

12‧‧‧ solder pads

13‧‧‧Protective layer

14‧‧‧ openings

20‧‧‧ catalyst layer

30‧‧‧ Nickel-plated bumps

40‧‧‧ outer sheath

40a‧‧‧ immersion gold (IG) layer

40b‧‧‧ thick gold (EG) layer

Claims (8)

A pad plating structure for a wafer pad, comprising: a wafer comprising: a surface; a plurality of pads disposed on the surface; and a protective layer formed on the surface and having a plurality of openings for corresponding Exposing the pads; a plurality of catalyst layers are formed by zincation to form a catalyst layer made of zinc on the surfaces of the pads; and a plurality of nickel-plated bumps are utilized. An electroless metal method of electrolytic nickel, in combination with a photoresist method, to form a bump of an appropriate height and made of electroless nickel on the surface of the catalyst layer on the surface of the pads; and a plurality of outer sheaths, Each of the outer sheath layers is formed on a surface of the nickel-plated bump layer, wherein each outer layer comprises at least one material selected from the group consisting of an immersion gold (IG) layer and a silver (ES) layer. The protective layer is formed by a photoresist process and is formed by one of a group selected from the group consisting of a gold process and a silver process. The wafer bump structure of the wafer pad of claim 1, wherein the outer sheath comprises an inner layer of immersion gold (IG) layer and a thick outer layer of gold (EG) layer. The method uses a gold plating process to form an immersion gold (IG) layer on the outer surface of the nickel-plated bump layer, and then form a thick gold on the outer surface of the immersion gold (IG) layer (EG). )Floor. The wafer bump structure of the wafer pad of claim 2, wherein the thickness of the nickel-plated bump layer is about 2-14 micrometers (μm), and the thickness of the gold-immersed (IG) layer It is about 0.01 to 0.05 micrometers (μm), and the thickness of the thick gold (EG) layer is about 0.5 to 2.0 micrometers (μm). The wafer bump structure of the wafer pad according to claim 1, wherein the outer sheath is a silver (ES) layer, which is processed by a silver plating process to form a nickel-plated bump layer. A silver (ES) layer is formed on the outer surface. The wafer bump structure of the wafer pad according to claim 4, wherein the nickel-plated bump layer has a thickness of about 2-14 micrometers (μm). The silver (ES) layer has a thickness of about 0.5 to 2.0 micrometers (μm). The chemically-plated bump structure of the wafer pad of claim 1, wherein the outer sheath comprises an inner layer of a silver layer and a layer of gold immersion in the outer layer, which utilizes silver The process comprises forming a silver layer on the outer surface of the nickel-plated bump layer, and then using a gold forming process to form a gold leaching layer on the outer surface of the silver layer. The wafer bump structure of the wafer pad of claim 6, wherein the thickness of the nickel-plated bump layer is about 2-14 micrometers (μm), and the thickness of the silver (ES) layer The thickness of the immersion gold (IG) layer is about 0.01 to 0.05 micrometers (μm), which is about 0.5 to 2.0 micrometers (μm). A method for manufacturing a pad bump structure for a wafer pad includes the steps of: providing a wafer having a surface, a plurality of pads disposed on the surface, and a first protective layer formed on the surface And forming a plurality of openings for correspondingly exposing the pads; forming a photoresist layer on the first protective layer and patterning the photoresist layer to form a plurality of openings for respectively exposing the pads and the pads a first protective layer surrounding a portion; using a zincation process to form a catalyst layer made of zinc on the surface of the pads; using an electroless nickel (electroless nicklee) method at the openings Forming a bump made of electroless nickel; in the state where the photoresist is still provided, using one of the groups selected from the group of gold processing and silver processing, respectively, on the upper surface of the bumps Forming an outer cover layer, wherein each outer cover layer comprises at least one protective layer composed of one material selected from the group consisting of a gold immersion layer and a silver layer; and removing the photoresist layer to expose the outer cover layer The bumps and the other than the bumps The protective layer.