CN100580899C

CN100580899C - Protruding block process

Info

Publication number: CN100580899C
Application number: CN200810095842A
Authority: CN
Inventors: 余瑞益; 戴丰成
Original assignee: Advanced Semiconductor Engineering Inc
Current assignee: Advanced Semiconductor Engineering Inc
Priority date: 2008-04-30
Filing date: 2008-04-30
Publication date: 2010-01-13
Anticipated expiration: 2028-04-30
Also published as: CN101266936A

Abstract

The invention provides bump manufacturing process, comprising: providing a chip, wherein the chip comprises an active surface comprising at least a contact pad; coating a protection layer on the active surface of the chip, exposing the contact pad; then forming a bump lower metal layer on the contact pad; and disposing a photographic film on the protection to coat the bump lower metal layer; then carrying out selective exposure on the photographic film so that a part of photographic film on the bump lower metal layer can be exposed; removing the exposed part of the photographic film to expose the bump lower metal layer; disposing a drop of solder paste on the bump lower layer, removing surplus photographic film on the chip; forming a metal bump with the solder paste via welding process.

Description

Projection technology

Technical field

The invention relates to a kind of projection technology, more be particularly to a kind of projection technology of utilizing the microbubble film on the projection lower metal layer, to form metal coupling.

Background technology

In conventional art, chip is to be connected with an external circuit by the routing mode, yet, with this connected mode, can cause on the space with frequency (high frequency) on use be restricted.Therefore, the chip bonding technology and replaced traditional routing mode in order to solve above-mentioned condition restriction, to have developed.

So-called chip bonding technology is to make projection lower metal layer (Under BumpMetallurgy earlier on chip; UBM), on the projection lower metal layer, form metal coupling again, and chip can be connected on the substrate by metal coupling in reflow (reflow) mode.

In the above-mentioned Flip Chip, with the metal coupling that conventional art forms, its structure is as shown in Figure 1.One connection pad, for example aluminium pad 22 is formed on the active surface 27 of wafer 20, and a protective layer 23 (passivation layer) is covered in the active surface of wafer 20 as an insulating barrier, and exposes connection pad 22.On connection pad 22, form a projection lower metal layer 24, and on projection lower metal layer 24, form a metal coupling 21.

With reference to figure 2, in general above-mentioned projection lower metal layer 24 includes three layers.The superiors of projection lower metal layer 24 are a wetting layer 33, and its material for example is a copper, and it acts in order good conjugation grade to be arranged with the metal coupling 21 of tin system; The orlop of projection lower metal layer 24 is an adhesion layer 31, and its material for example is an aluminium, and its effect engages in order to have closely with aluminium pad 22; And the intermediate layer of projection lower metal layer 24 is a barrier layer 32, and its material for example is nickel vanadium (NiV), and it acts in order to prevent that wetting layer 33 is penetrated into adhesion layer 31.

With reference to figure 3a to Fig. 3 g; traditional projection technology is to form connection pad 22 on the active surface 27 of wafer 20; on the active surface 27 of wafer 20, form protective layer 23 again; and expose connection pad 22; then forming the projection lower metal layer 24 that covers connection pad 22 on protective layer 23 (sees Fig. 3 a), form an eurymeric photoresist layer 42 (seeing Fig. 3 b) again on projection lower metal layer 24.One mask 40 then is set above connection pad 22, and photoresist layer 42 optionally exposed, make the photoresist layer 42 of position below mask 40 not be subjected to the irradiation of ultraviolet light because of the obstruct of mask 40, the photoresist layer 42 of position below mask 40 then is not subjected to the irradiation of ultraviolet light and produces chemical change (seeing Fig. 3 c).Wafer 20 after the exposure is inserted in the developing machine develop (figure does not show), and the photoresistance 42 that makes developer will produce chemical change is washed (seeing Fig. 3 d) off.With etching solution, for example copper etchant solution and aluminium etching solution carry out etching (seeing Fig. 3 e) to the projection lower metal layer 24 that is not covered by photoresistance 42, remove (seeing Fig. 3 f) after the etching and with photoresistance 42 again.After photoresistance 42 removes, on the active surface 27 of wafer 20, form a minus photoresist layer 50, and a mask 60 is set above connection pad 22, again photoresist layer 50 is optionally exposed, make that the photoresist layer 50 of position below mask 60 is unexposed because of the obstruct of mask 60, the photoresist layer 50 of position below mask 60 then do not produce chemical change (seeing Fig. 3 g) because of exposure.Use developer that the minus photoresist layer 50 of unexposed area is washed off, and the photoresist layer 50 of exposure area can be retained (seeing Fig. 3 h).Follow distribution one deck tin cream 70 on the projection lower metal layer 24 that exposes outside the photoresist layer 50, and make wafer 20 through reflow stoves (reflow oven) (figure does not show), to form the first shape (seeing Fig. 3 i) of tin ball.Utilize strong base solution that remaining photoresist layer 50 is removed, and allow wafer 20, so that tin cream 70 forms spherical metal coupling 21 (seeing Fig. 3 j) again through a reflow stove.

In the step that above-mentioned photoresistance 50 after will exposing with strong base solution removes, remove not only cost height of photoresistance 50 employed strong base solutions, and can corrode projection lower metal layer 24 and protective layer 23.

In view of this, just have to propose a kind of projection technology, to address the above problem.

Summary of the invention

The object of the present invention is to provide a kind of projection technology; can utilize Coating-removing machine easily remaining microbubble film on the wafer to be removed; must not use traditional acrid strong base solution that it is removed, thereby avoid solution to corrode the problem of projection lower metal layer and protective layer.

For reaching above-mentioned purpose; projection technology of the present invention is that the active surface in a wafer forms a connection pad; active surface in wafer forms a protective layer again; and expose connection pad; then cover a protective layer on the active surface of wafer; and expose connection pad, form a projection lower metal layer again on this connection pad.Then dispose a glued membrane on protective layer, and cover the projection lower metal layer.In the glued membrane top one mask is set again, and glued membrane is optionally exposed with UV light, make the glued membrane of position above the projection lower metal layer produce chemical change because of exposure, the glued membrane of position above the projection lower metal layer is then not unexposed because of the obstruct of mask, with developer the part of glued membrane exposure is washed off again.Follow distribution one deck tin cream on the projection lower metal layer outside exposing glued membrane, and make wafer through the first shape of reflow stove with formation tin ball.With UV light the residue glued membrane is carried out comprehensive exposure again, and use Coating-removing machine remaining glued membrane to be removed, and allow wafer again through a reflow stove, so that tin cream forms spherical metal coupling in the mode of dyestripping.

Since glued membrane used in the present invention can dyestripping after exposure mode easily will remove, and must not use traditional acrid strong base solution that it is removed, avoided solution to corrode the problem of projection lower metal layer and protective layer.

In order to allow above and other objects of the present invention, feature and the advantage can be more obvious, the embodiment of the invention cited below particularly, and cooperate appended diagram, be described in detail below.

Description of drawings

Fig. 1: the profile that is formed at the structure on the chip for the conventional metals projection.

Fig. 2: the profile that has the projection lower metal layer of three-decker for tradition.

Fig. 3 a to Fig. 3 j: be traditional projection technology.

Fig. 4 a to Fig. 4 i: be projection technology of the present invention.

Embodiment

With reference to figure 4a to Fig. 4 g; projection technology of the present invention is to form a connection pad 430 (to see Fig. 4 a) on the active surface 422 of a wafer 420; on active surface 422, form a protective layer 440 again; and expose connection pad 430 (seeing Fig. 4 b); wherein the material of this protective layer 440 for example is pi (Polyimide; Pl) or benzocyclobutene (bis-Benzo-Cyclo-Butene BCB) waits material.Then in for example mode shown in Fig. 3 b to Fig. 3 f; on protective layer 440, form a projection lower metal layer 450 (seeing Fig. 4 c) that covers connection pad 430; that is after projection lower metal layer 450 forms; form a photoresist layer thereon; again photoresist layer is optionally exposed; and after technologies such as development, etching, form the projection lower metal layer 450 shown in Fig. 4 c.

Forming a glued membrane 460 that covers projection lower metal layer 450 again on active surface 422, for example is microbubble film (micro-bubble film) (seeing Fig. 4 d).Then one mask 470 is set in glued membrane 460 tops, and glued membrane 460 is optionally exposed with UV light, make the glued membrane 460 of position above projection lower metal layer 450 because of exposure produces chemical change, the glued membrane 460 of position above projection lower metal layer 450 be not then because of the obstruct of mask 470 unexposed (seeing Fig. 4 e).Because the glued membrane 460 of position above projection lower metal layer 450 produces bubble because of being subjected to the UV rayed, its tackness thereby reduction can be washed it off (seeing Fig. 4 f) by developer easily.Then on the projection lower metal layer 450 in exposing glued membrane 460 outside with the mode of for example printing one deck tin cream 480 ' (seeing Fig. 4 g) that distributes, and make wafer 420 through the first shape (seeing Fig. 4 h) of reflow stoves (figure does not show) with formation tin ball.Then, with UV light residue glued membrane 460 is carried out comprehensive exposure again, make that remaining glued membrane 460 produces chemical change and produces microbubble because of exposure on the wafer 420, therefore reduce the adhesive force between glued membrane 460 and wafer 420 surfaces.Re-use Coating-removing machine (de-taping machine) and remaining glued membrane 460 is removed, and allow wafer 420, so that tin cream 480 ' forms spherical metal coupling 480 (seeing Fig. 4 i) again through a reflow stove in the mode of dyestripping.

Since glued membrane 460 used in the present invention can dyestripping after exposure mode easily will remove, and must not use traditional acrid strong base solution that it is removed, avoided solution to corrode the problem of projection lower metal layer 450 and protective layer 440.

Though the present invention discloses with aforementioned preferred embodiment, so it is not in order to limiting the present invention, anyly has the knack of this skill person, without departing from the spirit and scope of the present invention, and when doing various changes and modification.Therefore protection scope of the present invention is as the criterion when looking appended the claim person of defining.

Claims

1. projection technology comprises the following step:

One wafer is provided, and this wafer has an active surface and at least one connection pad is formed on this active surface;

Protective mulch and exposes this connection pad on the active surface of this wafer;

Form the projection lower metal layer on this connection pad;

Dispose glued membrane on this protective layer, and cover this projection lower metal layer, wherein this glued membrane is the microbubble film;

This glued membrane is optionally exposed, make the glued membrane that is positioned at this projection lower metal layer top be exposed;

Remove the exposed portion of this glued membrane, and stay the unexposed part of this glued membrane, so that this projection lower metal layer is exposed;

The distribution tin cream is on this projection lower metal layer;

Remaining glued membrane exposure back removes this remaining glued membrane with Coating-removing machine on this wafer; And

Make this tin cream form metal coupling by a reflow process.

2. projection technology as claimed in claim 1, wherein the exposed portion of this glued membrane is to remove with developer.

3. projection technology as claimed in claim 1 wherein is to use mask that this glued membrane is optionally exposed.

4. projection technology as claimed in claim 1 is wherein being carried out another reflow process after the step of described distribution tin cream on this projection lower metal layer and in described more comprising before remaining glued membrane exposure back removes the step of this remaining glued membrane with Coating-removing machine on this wafer.