TWI237369B - Bump structure - Google Patents

Abstract

A wafer bump structure mainly comprises wafer pads, under bump metallurgy layers and bumps. Therein, the wafer pads are formed on an active surface of the wafer and exposed out of openings formed in a passivation layer over the active surface, and each under bump metallurgy layer is formed over the corresponding wafer pad. Each under bump metallurgy layer includes an adhesive layer, a barrier layer, and a wetting layer which are sequentially formed on the wafer pads. Specifically, the material of the barrier layer mainly includes nickel-copper alloy.

Description

善 1237369 " " ^ ~ ^ — ^ 119199 ^ Ά, description of the invention (1) '---) too [Technical field to which the invention belongs] ^ The month is about a kind of convex structure, and especially about a day yen The structure of the wafer bump that changes the bonding strength between the 〃 ~ 枓 bumps in the pad. (Revision 1), [Previous Technology] Today, the multimedia application market is eager to expand the network integrated circuit packaging technology to the digitalization of electronic devices. The above-mentioned points: domain connection and use Humanized trends. In order to achieve Sekisui's electronic components, it is necessary to cooperate with various requirements such as high-speed processing, multi-functionalization, weight reduction of body electric daggers, and low cost. Therefore, the technology of sealing liquid of Jietai Road has also developed toward miniaturization and high density . t Φ step ° array structure (Bal 1 Gr id Array, BGA), chip size structure (Chip-Scale package, cSP), flip-chip structure (Flip 々Ch ^ p 'f / C), multi-chip mold Group (Multi-Chip Module, Mcm) and other two-density integrated circuit packaging technologies have also been developed. The flip chip packaging technology (Flip Chip Packaging Techno 1 ogy) mainly uses an array arrangement (aregl array) to arrange multiple bonding pads on the active surface of the die. And bumps are formed on each wafer pad, and after the wafer is flipped, the bumps of the wafer pad are used to electrically and mechanically connect to the substrate ( substrate) or a mounting pad corresponding to the surface of a printed circuit board (PCB). In addition, since the flip-chip bonding technology can be applied to a high pin count (High Pin Count) chip packaging structure, and has many advantages such as reducing the package area and shortening the signal transmission path, so

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1237369 taken _ case number 93119199 V. Description of the invention (2) The flip-chip bonding technology has been widely used in the field of chip packaging. • The so-called wafer bump process is commonly used in flip chip technology, which is mainly the external contact (usually a metal pad; that is, a crystal pad) on a wafer where multiple wafers are formed. Under the bump metal layer structure (UBM, Under Bump Metallurgy Structure) is formed, and then bumps or implanted solder balls are formed on the bottom metal layer structure to serve as the subsequent electrical conduction between the wafer and the substrate. Connection interface. Please refer to FIG. 1, which is a conventional semiconductor wafer 100 structure. The wafer 100 has a protective layer 102 and a plurality of wafer pads 104 exposed through the protective layer 102 openings. In addition, a ball-bottom metal layer 106 (also referred to as a ball-bottom metal layer structure) is formed on the wafer pad 104, and a solder bump 108 is formed on the ball-bottom metal layer 106. The ball bottom metal layer 106 is disposed between the wafer pad 104 and the solder bump i 08 and serves as a bonding interface between the wafer pad 104 and the solder bump 108. Please refer to FIG. 1 again, the conventional ball bottom metal layer 106 mainly includes an adhesion layer 106a, a barrier layer 106b, and a wetting layer 106c. The adhesive layer ι〇6 & is used to increase the bonding strength between the wafer pad 104 and the barrier layer 106b, and the material is, for example, a metal such as aluminum or titanium. The barrier layer 1061) is a metal that diffuses on the upper and lower sides of the barrier i 〇6 b (diffusi =, and its commonly used materials are, for example, nickel-vanadium alloy and nickel. In addition, the wetting layer 106c is It is used to increase the wettability of the ball bottom metal layer 10 to the solder bump 108. Its common materials include metals such as copper. It is worth noting that because tin gas alloys have better soldering properties, solder The material of bump 1 08 is often tin alloy, but the effect of lead on the natural environment

Case No. 93119199_ YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY etc. etc., etc. 5. The description of the invention (3) is huge, so there is the birth of lead free solder. The lead or lead-free solders include tin. Please continue to refer to Figure 1; in general, tin reacts very easily with copper, so when the composition of the wetted layer 1 0 6 c of the ball bottom metal layer 106 includes copper, during the reflow (Ref low) The tin of the solder bump 1 08 easily reacts with the copper of the wetting layer 10 6 c to generate an inter-metal compound (IMC) between the wetting layer 10 6 c and the solder bump 1 08. ) To generate C u eS ns. In addition, when the composition of the barrier layer 1 0 6 b of the ball-bottom metal layer 10 6 mainly includes nickel alloy or nickel, during reflow, the tin of the solder bump 1 08 and the wetting layer 10 first The 6 c copper reacts to form an intermetallic compound, that is, Cu 6S η 55 is formed. Then the tin of the solder bump 108 is reacted with the barrier layer ι〇6 b to form another intermetallic compound, which forms N i jn. 4. It is worth noting that due to the long reaction between the tin of the recording bump 108 and the nickel of the barrier layer 106b, the intermetallic compound (that is, NhSnJ is a discontinuous structure, so that This makes the solder bump 108 easy to come off from here. Therefore, how to provide solutions to the above problems is indeed an important subject of the present invention. (3) [Summary of the Invention] In view of this, the object of the present invention is to propose a bump junction Containing a ball-bottom metal layer, it is suitable for disposing on wafer pads and solders, in the meantime, it is used to slow down the intermetallic compounds (that is, the formation of N 丨 A to solve the problem that the fresh material bumps are easy to fall off, so it can be long Timely maintain the bonding strength between the parallel block and the wafer pad, and then increase the life of the wafer sealing material. The structure of the edge is' To achieve the above purpose, the present invention proposes a wafer u block Μ

1237369 ^^ 93H9199 _ year month 倏 月 _ V. Description of the invention (4) structure, which includes a wafer 'a plurality of wafer pads' a plurality of ball-bottom metal layers and a plurality of bumps. The plurality of wafer pads are disposed on the active surface of the wafer and expose a protective layer disposed on the active surface of the wafer. The ball-bottom metal layer has at least: an adhesive layer disposed on the wafer pad; a barrier layer disposed on the adhesive layer; a wetting layer disposed on the barrier layer; and the barrier layer is mainly It is composed of a nickel-copper alloy, such as a nickel-copper alloy layer, which is used to slow down the formation rate of the intermetallic compound between the barrier layer and the solder bump, so as to prevent the tin of the solder bump from reacting with the barrier layer to form a metal on the bottom of the ball. An intermetallic compound with poor bonding strength is generated in the layer to solve the problem that the solder bump is easy to fall off.

The reason is that in order to achieve the above-mentioned object, the present invention proposes a ball-bottom metal layer structure suitable for being disposed on a wafer pad of a wafer, and the wafer further has a protective layer to expose the wafer pad. Wherein the ball-bottom metal layer structure includes an adhesive layer disposed on the wafer pad; a barrier layer disposed on the adhesive layer, and the material of the barrier layer is nickel-copper alloy; and a lubricant Wet |, placed on the barrier layer.

The reason is that in order to achieve the above-mentioned object, the present invention proposes a substrate pad structure, the substrate pad structure is formed on a substrate, and an opening of a solder mask layer of the substrate exposes the substrate pad structure, The substrate pad structure includes a substrate pad; a first metal layer disposed on the substrate pad; a nickel-copper alloy layer disposed on the first metal layer; and a second metal layer disposed On the nickel-copper alloy layer. To sum up, 'Since the barrier layer is mainly composed of a nickel-copper alloy in the present invention, the reaction rate between tin and the nickel of the barrier layer can be slowed down, and the tin and the barrier layer of the earth recording bump can be further prevented. Nickel reaction produces discontinuous massive structure

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93Π9199 V. Intermediate metal compound of invention description (5) (that is, Ni3Sn4 is formed). (4). [Embodiment] The block i will be referred to the related figure < 'Explanation of the preferred embodiment of the present invention according to the second embodiment " Figure 2' It shows the crystal according to the preferred embodiment of the present invention A schematic cross-sectional view of a circular bump structure. / 20 (ηΛ · 参 / Figure 2 'is a schematic diagram showing a part of the wafer 200. The wafer protection layer 202 and the wafer fresh wafer 204, and the wafer wafer 204 on the wafer = the bottom of the ball Metal layer 206. The protective layer 002 is arranged on the surface of the wafer as the surface of the round wafer 200 and has an opening exposing the solder pad 204 to make a second = a contact for electrical connection; and a ball-bottom metal layer It is mainly composed of adhesive layer 206 and wetting layer 206. Among them, the barrier layer a ± 糸 is composed of nickel-copper alloy. When the wafer pad 204 is an aluminum pad, the acoustic bonder layer 7 resists The barrier layer / wetting layer is preferably inscribed / recorded copper alloy / copper 32, s temperature 4 and when the wafer pad 2 is a copper pad, the adhesion layer / barrier layer / layer is preferably It can be a three-layer structure of titanium / nickel-copper alloy / copper. However, no matter what material is composed of θ, barrier layer, and wetting layer, in general, the material of the adhesive layer is selected from titanium, tungsten, One material of the group consisting of titanium-tungsten alloy, chromium, and aluminum; and the material of the wetting layer is selected from the group consisting of copper, chrome-copper, copper alloy, iron, iron alloy, cobalt, and cobalt alloy. Among them, the adhesive layer Barrier layer The layer can be formed by sputtering or electroplating. As mentioned above, since the solder bump 208 (preferably by the tin boat weight ratio is about 5: 95 or 3: 9 7 or 10). ·· 9 0), and finally formed in the wetting layer

Page 10 Case No. 93Π9199 1237369

V. Description of the invention (6) On the 2 0 6 c, the fresh material bumps and copper in the wetting layer 2 6 c react with each other when the fresh material bumps 208 are fresh, and then the plaque / 08 The tin series reacts first with 20 6b. Therefore, in the present invention, the copper layer in the barrier layer of the tin layer and the copper reaction in the barrier layer 206b can reduce the reaction rate recorded in the embroidery & wetting layer 206c. Therefore, it is possible to avoid too much of the antimony to react in a longer period of time. And the intermediate metal compound with a bulk structure in the metal layer of the bottom of the ball (that is, the block of N 丨, Ge, 2 0 8 and the bottom of the ball after resoldering) It can be seen from the above that the main features of the present invention are the barrier layer of the two-two copper alloy, and the wetting layer between the two layers of solder and the solder layer. , Nickel >, bamboo bumps are connected to form a ball-bottom metal layer, so solder bumps can be prevented from being contained in other substructures in the ° formation: = = = = Compounds (that is, formed ...; forming the bonding strength between the solderless bumps and the ball-bottom metal layer. In addition, ^ the melting point of the solder bumps during the refreshing step or within a certain period of time When the heating reaction is performed at the following degree, the tin in the solder bump can be caused to react with the copper from the bottom of the ball: the copper of the metal layer forms a continuous block of tin-copper alloy axe. It can also be applied to the copper pads of general substrates (as shown in Figures 3A and 3B), that is, the substrate pads exposed by the openings of the solder mask on the substrate 300. On the 3 0 4 ′, a convergent metal layer 306a, a copper alloy layer 306 b, and a copper metal layer 3 0 6 c may be sequentially formed as a transition layer for the substrate pad 3 0 4 and a solder ball or bump to be joined. 3 0 6. To improve the bonding strength between the solder balls or bumps and the substrate 300. Among them, Figure 3 A shows that the substrate welding pad 3 04 is covered by the solder mask layer 3 02; and Figure 3 B shows The substrate pads 3 0 4 all expose the masking layer.

Page 11 1237369 Case No. 93119199 Amendment V. Description of Invention (7) One of the 3 0 2 'openings. In addition, as shown in FIG. 4A, the ball bottom metal layer structure 4 of the present invention may also be composed of a first conductive layer 406a, a nickel-copper alloy layer 406b, and a second conductive layer 406c. The first conductive layer 4 The material of 0 6 a is selected from the group consisting of titanium, tungsten, titanium alloy, chromium, and aluminum, and the material of the second conductive layer 40 6 c is selected from copper, chromium-copper alloy, and One of the materials in the group of copper alloys; and the first conductive layer 406a is directly disposed on the wafer pad 400, and the second conductive layer 406c can be directly phased with the solder bump 408. connection. Furthermore, when the ball-bottom metal layer extends on the wafer as a circuit redistribution layer 4 10 (as shown in FIG. 4B), a part of the ball-bottom metal layer can also form a circuit redistribution pad, which is formed by The redistribution layer 4 1 0 is formed by exposing the opening 4 1 2 of the dielectric layer (dielectric protection layer) 4 1 2, and the material of the uppermost metal layer of the redistribution pad is mainly copper or copper. alloy. The circuit redistribution layer may include an adhesive layer 4 1 0 a, a barrier layer 4 1 0 b, and a wetting layer 410c ′. The dielectric layer (dielectric protective layer) 41 2 may be made of polyisocyanate. It is composed of polymer materials such as amine (PI) or Benzocyclobutene (BCB). The specific embodiments proposed in the detailed description of this embodiment are only for easy explanation of the technical content of the present invention, and do not limit the present invention to this embodiment in a narrow sense. Therefore, the spirit and the following applications are not exceeded. The scope of patents can be implemented in various ways.

Page 12 1237369 Case No. 93119199_Year Month Amendment_ Brief Description of Drawings (5) [Simplified Description of Drawings] Figure 1 is a schematic cross-sectional view of the structure of a conventional ball bottom metal layer. FIG. 2 is a schematic cross-sectional view of a bump structure according to a preferred embodiment of the present invention. FIG. 3A is a schematic cross-sectional view of a substrate pad structure applied to a substrate pad according to a preferred embodiment of the present invention. FIG. 3B is a schematic cross-sectional view of a substrate pad structure according to another preferred embodiment of the present invention applied to a substrate pad. Fig. 4A is a schematic sectional view of a bump structure according to another preferred embodiment of the present invention. 4B is a schematic cross-sectional view of a bump structure according to another preferred embodiment of the present invention. [Explanation of component symbols: 100 wafer 102 protection layer 104 wafer pad 106 ball metal layer 1 0 6 a: adhesive layer 1 6 b: barrier layer 1 0 6c · wetting layer 108 solder bump 200 wafer 202 protective layer

Page 13 1237369 Case No. 93119199 Revised diagram for simple explanation 2 0 4: Wafer pad 2 0 6: Ball-bottom metal layer 2 0 6 a: Adhesive layer 2 0 6 b: Barrier layer 2 0 6 c: Wetting layer 2 0 8: solder bump 3 0 0: substrate 3 0 2: solder mask layer 3 0 2 ': solder mask layer 3 0 4: substrate pad

3 0 6: Transition layer 306a: Titanium metal layer 306b: Nickel copper alloy layer 306c: Copper metal layer 4 0 0: Wafer

4 0 2: Protective layer 4 0 4: Wafer pad 4 0 6: Ball-bottom metal layer structure 4 0 6a: First conductive layer 406b: Second conductive layer 4 0 8: Solder bump 4 1 0: Circuit weight Distribution layer 410a: Adhesive layer 410b: Barrier layer

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Claims (1)

Case No. 93119199_Revision of the month of the year_ 6. Application for Patent Scope 1 · A ball-bottom metal layer structure is suitable for being disposed on a wafer pad of a wafer 'the wafer further has a protective layer to expose the Wafer welding pad, wherein the ball-bottom metal layer structure includes: an adhesive layer disposed on the wafer pad; a barrier layer disposed on the adhesive layer, and the material of the barrier layer is nickel-copper alloy ; And a wetting layer disposed on the barrier layer. 2. The ball-bottom metal layer structure according to item 1 of the scope of the patent application, further comprising a solder bump, and the solder bump is disposed on the wetting layer. 3. The ball-bottom metal layer structure as described in item 2 of the scope of the patent application, wherein the weight ratio of tin to lead of the solder bump is 5:95. 4. The ball-bottom metal layer structure according to item 2 of the scope of the patent application, wherein the solder-to-lead weight ratio is 3: 97. 5. The ball-bottom metal layer structure according to item 2 of the scope of the patent application, wherein the weight ratio of tin to lead of the solder bump is 10:90. 6. The ball-bottom metal layer structure according to item 1 of the scope of patent application, wherein the material of the adhesive layer is one selected from the group consisting of titanium, tungsten, titanium-tungsten alloy, chromium, and aluminum. Page 16 1237369 Case No. 93119199 Amendment 6. Scope of patent application 7 · The ball-bottom metal layer structure described in item 1 of the scope of patent application, wherein the material of the wetting layer is selected from copper, chrome copper alloy and copper alloy One of the materials in the group. 8. The ball-bottom metal layer structure according to item 1 of the scope of patent application, wherein the barrier layer is formed by electroplating. 9. The ball-bottom metal layer structure according to item 1 of the patent application scope, wherein the barrier layer is formed by sputtering. 10 · The ball-bottom metal layer structure described in item 1 of the scope of patent application, further comprising a dielectric layer, wherein the ball-bottom metal layer is a circuit redistribution layer, and the dielectric layer is formed on the circuit. An opening is exposed on the distribution layer to expose the circuit redistribution layer to form a circuit redistribution pad. π The ball-bottom metal layer structure described in item 1 of the scope of the patent application, wherein the anti-blocking conductive layer comprises a nickel-copper alloy layer. 1 2 · A substrate pad structure, the substrate pad structure is formed on a substrate, and an opening of a solder mask layer of the substrate exposes the substrate pad structure, wherein the substrate pad structure includes : A substrate pad; a first metal layer disposed on the substrate pad; a nickel-copper alloy layer disposed on the first metal layer; and Page 17 1237369 Case No. 93Π9199 Amendment VI. Scope of patent application A second metal layer is arranged on the nickel-copper alloy layer. 1 3 · The substrate pad structure according to item 12 of the scope of patent application, wherein the mask layer covers a part of the second metal layer. 14. The substrate pad structure according to item 12 of the scope of patent application, wherein the opening completely exposes the second metal layer. 15. The substrate pad structure according to item 12 of the scope of patent application, wherein the material of the first metal layer is one selected from the group consisting of titanium, tungsten, titanium-tungsten alloy, chromium, and aluminum. . 16. The substrate pad structure according to item 12 of the scope of the patent application, wherein the material of the second metal layer is one selected from the group consisting of copper, chrome copper alloy and copper alloy. 17. The substrate pad structure according to item 12 of the scope of the patent application, wherein the substrate pad is a copper pad. Page 18 Exactly 1237369 The invention patent specification BUMP STRUCTURE First name inventor (1 person) a 1. HUANG, MIN-LUNG 1. Chinese name or first name in the residence of TW in the Republic of China! C) Name 1 Name in English (t applicants (1 person) 1. 10th Floor, No. 8, Lane 2, Lane 33, Lane 33, Dingyong, Sanmin District, Yanxiong City * Kaohsiung 'Taiwan ^ O ?! DingyUng St-, Sanmin Chiu, 1.Sun Moon Semiconductor Manufacturing Co., Ltd. 1. ADVANCED SEMICONDUCTOR ENGINEERING, INC. 1 .Taiwan resident of the TW Office 1.811 No. 26 Jingsan Road, Nanzi Processing Zone, Kaohsiung City (this address is the same residence as the applicant (business office) t English) 1.26 Chin 3rd Rd., Nantze Export Processing Zone Kaoshiung, Taiwan, R. 0. C. Representative (Chinese) 1. Zhang Qiansheng (W) 1. CHANG, JASON