RU2671383C1 - Method for forming ball leads based on aluminum metalization of crystal contact areas - Google Patents

Method for forming ball leads based on aluminum metalization of crystal contact areas Download PDF

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Publication number
RU2671383C1
RU2671383C1 RU2017144961A RU2017144961A RU2671383C1 RU 2671383 C1 RU2671383 C1 RU 2671383C1 RU 2017144961 A RU2017144961 A RU 2017144961A RU 2017144961 A RU2017144961 A RU 2017144961A RU 2671383 C1 RU2671383 C1 RU 2671383C1
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RU
Russia
Prior art keywords
crystal
ball
leads
aluminum
contact pads
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RU2017144961A
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Russian (ru)
Inventor
Виктор Васильевич Зенин
Никита Владимирович Рогозин
Виталий Владимирович Побединский
Анатолий Александрович Колбенков
Евгений Вячеславович Лаврентьев
Александр Валерьевич Рябов
Кирилл Сергеевич Князев
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Акционерное общество "Научно-исследовательский институт электронной техники"
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Priority to RU2017144961A priority Critical patent/RU2671383C1/en
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/31Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers
    • H01L21/3205Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
    • H01L21/321After treatment

Abstract

FIELD: manufacturing technology.SUBSTANCE: use for the manufacture of integrated circuits (IC), hybrid integrated circuits (HIC), microassemblies and modules. Essence of the invention lies in the fact that on the contact areas of the crystal, ball leads are formed from the platinum wire by the thermo-sound welding method, and after the planarization of the ball leads, a solder ball is applied to them for subsequent soldering the crystal to the body / substrate using the "flip-chip" technology.EFFECT: providing the possibility of increasing reliability and rapid prototyping without the use of templates.1 cl, 3 dwg

Description

The invention relates to the field of electronics and is intended for the manufacture of integrated circuits (ICs), hybrid integrated circuits (GIS), microassemblies and modules. One of the main operations in the production of ICs is the attachment of crystals with ball leads to the bases of the housings or substrates by the flip-chip method. The inverted crystal method is based on ball leads located on metallized contact pads of crystals.

The crystals are mounted on the base of the housings or substrates with the planar side. At the same time, the drawing of their contact pads is a mirror image of the location of the terminals.

The reliability of integrated circuits, including those made using the flip-chip technology, depends both on the material of the IC contact pad and on the material of the ball output. The use of soldered ball leads not only provides an electrical connection between the IC crystals and the substrate (circuit board), but also plays an important role in the mechanical, strength, temperature, heat removal components of components assembled using the flip-chip technology. In addition, it is possible to use in technologies 3D-IC, SiP (system-in-package), micro-electromechanical systems (MEMS), WLCSP (wafer level chip scale package - encasing to the size of a crystal at the wafer level). On the one hand, the implementation of connections on a solder ball lead, in comparison with a wire connection, reduces the propagation delay of electrical signals, provides greater bandwidth, reduces the resistance and inductance of electrical connections, which reduces the propagation delay of electrical signals, provides a large bandwidth and reduces power and ground bus restrictions.

On the other hand, the use of soldered ball leads contributes to the miniaturization of the product, for example, in the field of mobile communications.

Installation on soldered ball leads displaces wire connections, which significantly reduces the size of the housing of microcircuits and the overall performance of the final products.

An important role in the installation of soldered ball leads is played by multilayer metallization - UBM (Under Bump Metallization), which is recommended as stud bump (the first point of thermosonic welding on a crystal in a ball-wedge connection).

The development of methods and technologies for the production of ICs is an urgent task, the solution of which is aimed at the efforts of all specialists working in the field of semiconductor microelectronics.

There are various ways of forming ball leads on the contact pads of a chip for assembling ICs using flip-chip technology.

A known method of forming gold bars on aluminum contact pads of the crystal [1]. This technology is used in the automated installation of crystals on a tape medium. In this case, columns of gold are obtained by electrolytic deposition on aluminum contact pads of a crystal after opening a passivating layer.

After ion cleaning, a contact barrier layer 100 nm thick is applied, which serves as a conductive layer during electrolytic deposition of gold. The main disadvantage that affects the yield of suitable devices is the selective etching of the layers deposited by vacuum or ion-beam spraying. In addition, during chemical etching of these layers, the etchant can penetrate the passivating coating and dissolve the aluminum interconnect. Moreover, the formation of gold bars on aluminum contact pads leads to the formation of Au x -Al intermetallic compounds at the boundary, which reduces the reliability of the contacts.

Known [2] is the process of forming gold bars on an aluminum contact pad. Columns of gold 25 microns high were obtained by electrolytic deposition. The main drawback of this technology is the formation of intermetallic compounds Au x -Al y in contact of these metals ( "purple plague"), which significantly reduces the reliability of contacts. In addition, electrolytic deposition is a rather time-consuming process, which increases the cost of manufactured products. Moreover, after electrolytic deposition, it is necessary to wash and dry the crystals in the composition of the plate.

Closest to the technical nature of the claimed invention is a method [3] of the formation of contact ledges by thermocompression joining a ball of gold wire to aluminum contact pads on a chip. According to this technology, a pointed protrusion remains on the top of the ball - a trace of wire breakage. In order to obtain contact protrusions having uniformity in size and shape, the protrusion is first flattened using a forming needle that has a flat or curved working surface, and then the ball is thermally treated with a laser beam. The main disadvantage of this method is the formation of intermetallic compounds Au x -Al at the border of a gold ball with an aluminum contact pad, which significantly reduces the reliability of these compounds.

It should be noted that when thermocompression gold wire joining method for aluminum metallization in the contact zone of gold-aluminum intermetallic compounds formed of Au x -Al y, which significantly reduces the reliability of connections.

The problem to which the claimed invention is directed is the ability to implement the flip-chip technology by soldering crystals with aluminum metallization without preliminary preparation of contact pads and applying UVM, rapid prototyping, these factors reduce the cost of manufactured products.

This task is achieved by the fact that on the aluminum contact pads of the crystal, ball leads from platinum wire are formed by thermosonic welding, and after planarization of the ball leads, a solder ball is applied to them for subsequent soldering of the crystal on the body / substrate using the flip-chip technology.

Comparison of the proposed method for the formation of ball findings on aluminum metallization of the contact pads of the crystal with other methods [1-3] from the prior art also did not allow to reveal the signs claimed in the characterizing part of the formula.

The invention is illustrated by drawings, which schematically depict:

in FIG. 1 is a diagram of a formed stud bump on an aluminum contact pad of a crystal by a thermosonic welding method;

in FIG. 2 - stud bump after instrument planarization;

in FIG. 3 is a diagram of a solder ball lead with a platinum core.

The insulating protective layer around the perimeter of the contact pad of the crystal in FIG. 1-3 is not shown.

The assembly receives semiconductor crystals 1 with aluminum contact pads 2 (Fig. 1). Platinum stud bumps 3 are formed on aluminum contact pads 2 of a silicon crystal 1 by the method of thermosonic welding "ball", which is used in the formation of a butt joint. At the same time, on the upper part of the stud bump there remains a pointed protrusion 4 (a section of wire breakage).

Thermosonic welding, in contrast to thermocompression welding, is realized at lower pressure and temperature, which positively affects the interlayer dielectric (no cracks), on which aluminum metallization is sprayed. In addition, the butt weld “ball" is smaller in comparison with the connection obtained by thermal compression lap. Thus, thermosonic “ball” welding helps to reduce the size of the contact area itself and, in general, to reduce the size of the crystal. This factor reduces the cost of semiconductor products.

Then the stud bumps are subjected to “embossing” (Fig. 2) - planarization using a specially designed tool, while the stud bumps acquire a surface 5 parallel to the crystal 1 with metallization 2.

After planarization of the stud bumps, calibrated solder ball leads 6 from the solders of a given composition and the melting temperature by laser fusion are applied to them (Fig. 3). Solder wetting occurs on the entire surface of the planarized stud bumps 5, as a result of this a solder ball lead with a platinum core is formed on the aluminum contact pad.

In the proposed method, platinum (stud bumps) is used, followed by the application of solder ball leads for the flip-chip technology. This approach is convenient for rapid prototyping and does not require the use of templates. The formation of stud bumps by this method is possible on the contact pads of crystals in the wafer, which reduces the cost of manufactured semiconductor products.

In addition, the use of platinum is explained by its physical characteristics compared to gold, namely: diffusion barrier properties, wettability with solders, corrosion resistance, low electrical resistance. The rate of dissolution of platinum in molten tin is much lower than that of nickel, a traditional barrier material for metallization of IC contact pads.

Typically, the solder pads have a multilayer structure that includes an oxidation protection layer, a diffusion barrier layer, and a solder wetting layer. An example of such a multilayer structure is a three-layer metallization of Au / Ni / Cu, where the Au layer is introduced to protect against oxidation, the Ni layer is a diffusion barrier layer, and Cu is a layer for conductive paths.

It is known that the main disadvantage of using multilayer metal structures on the contact pads of the crystal leads not only to an increase in the cost of production of final products with such pads, but also increases the complexity of their design and manufacture. An increase in complexity, in turn, leads to problems associated with a decrease in the reliability of microelectronic products.

Thus, there is a motivation to simplify the multilayer metal structure. Platinum as a chemical element is not susceptible to oxidation and has a slow reaction rate with solders based on Pb-Sn, Sn-Cu, and Sn-Ag-Cu and solders based on pure tin. In view of these properties, platinum metallization can perform both the functions of a layer that protects against oxidation and the functions of a diffusion barrier layer. The use of platinum as UVM contact pads for ball solder terminals for mounting crystals using the flip-chip method is technically and economically justified in this case.

Based on the foregoing, it was concluded that the proposed method for forming ball terminals on aluminum metallization of the contact pads of the crystal provides the following advantages compared to existing methods:

1. The cost of production is reduced;

2. Increases reliability;

3. The ability to quickly prototype without using templates.

Information sources

1. VLSI technology. T. 2. / Ed. S. Zee. M .: Mir, 1986.

2. Emelyanov V.A. Integrated circuit packaging. Minsk: Polyfact, 1998 .-- p.194-195.

3. The formation of contact ledges. Application 212919 Japan. MKI 5 H01L 21/321 / Matsumura Yasco; Kansai Nippon Denki K.K.-№63-164563; Claim 06/30/1988; Publ. 01/17/1990 // Kokai Tokkyo Koho. Ser. 7 (2). -1990. -16.-C.113-116.

Claims (1)

  1. The method of forming ball leads on aluminum metallization of the contact pads of the crystal by thermal compression of the gold wire, characterized in that balls of platinum wire are formed by thermosonic welding on the contact pads of the crystal, and after planarization of the platinum balls (stud bumps) a solder ball is applied to them for subsequent soldering of the crystal on the case / substrate using flip-chip technology.
RU2017144961A 2017-12-20 2017-12-20 Method for forming ball leads based on aluminum metalization of crystal contact areas RU2671383C1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2717264C1 (en) * 2019-02-12 2020-03-19 Акционерное общество "Научно-исследовательский институт электронной техники" Method of using platinum metallization in system of redistribution of contact pads of crystals of integrated microcircuits and semiconductor devices
RU2734854C1 (en) * 2020-01-29 2020-10-23 Акционерное общество «Российская корпорация ракетно-космического приборостроения и информационных систем» (АО «Российские космические системы») Method for multi-crystal modules thermo-sound micro-welding

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007112393A2 (en) * 2006-03-27 2007-10-04 Fairchild Semiconductor Corporation Semiconductor device with solderable loop contacts
KR20080062565A (en) * 2006-12-29 2008-07-03 주식회사 하이닉스반도체 Flip chip package
US20150194409A1 (en) * 2014-01-03 2015-07-09 Wire Technology Co., Ltd. Stud bump and package structure thereof and method of manufacturing the same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007112393A2 (en) * 2006-03-27 2007-10-04 Fairchild Semiconductor Corporation Semiconductor device with solderable loop contacts
KR20080062565A (en) * 2006-12-29 2008-07-03 주식회사 하이닉스반도체 Flip chip package
US20150194409A1 (en) * 2014-01-03 2015-07-09 Wire Technology Co., Ltd. Stud bump and package structure thereof and method of manufacturing the same

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
Guy V. Clatterbaugh, Charles V. Banda, and S. John Lehtonen, Reliable Miniature Electronic and Optical Interconnects for Low-Volume Applications, Johns Hopkins APL Technical Digest, Volume 28, Number 1, 2008. *
Guy V. Clatterbaugh, Charles V. Banda, and S. John Lehtonen, Reliable Miniature Electronic and Optical Interconnects for Low-Volume Applications, Johns Hopkins APL Technical Digest, Volume 28, Number 1, 2008. Mark Fretz, Flip Chip Bonding Technologies for Hybrid Integration, Universite de Neuchatel, 24 septembre 2009. *
Mark Fretz, Flip Chip Bonding Technologies for Hybrid Integration, Universite de Neuchatel, 24 septembre 2009. *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2717264C1 (en) * 2019-02-12 2020-03-19 Акционерное общество "Научно-исследовательский институт электронной техники" Method of using platinum metallization in system of redistribution of contact pads of crystals of integrated microcircuits and semiconductor devices
RU2734854C1 (en) * 2020-01-29 2020-10-23 Акционерное общество «Российская корпорация ракетно-космического приборостроения и информационных систем» (АО «Российские космические системы») Method for multi-crystal modules thermo-sound micro-welding

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