JP2006147880A - Method and device for bonding semiconductor with solder bump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems concerning bonding tact, use of flux, injection of a thermosetting resin, and a decrease in reliability in bonding a semiconductor with solder bumps. <P>SOLUTION: A method for bonding the semiconductor with the solder bumps includes at least a process of supplying the thermosetting resin 7 to a board 2 in advance, a process of supplying the semiconductor 1 with the solder bumps to set the semiconductor 1 on the thermosetting resin 7, and a process of heating the semiconductor 1 with the solder bumps 3 locally by a noncontact heat source 9 to melt the solder bumps and bonding the solder bumps to electrodes 4 on the board 2. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

The present invention relates to a method for joining semiconductors with solder bumps and a semiconductor joining device with solder bumps.

In recent years, semiconductor devices have become lighter, thinner, smaller, and more advanced, and semiconductors with solder bumps (hereinafter referred to as chips) are mounted directly on the board in order to meet the high-density mounting requirements. Flip chip bonding has been developed. In this method, after turning over the chip (flip chip) on the substrate using the solder on the chip side and the substrate electrode on the substrate side, the solder is melted and bonded.

  FIG. 2 is a cross-sectional view showing a state in which flux is supplied onto a solder bump portion of a chip and a substrate electrode in a conventional flip chip method. Conventionally, when the chip 1 is bonded to the substrate 2 by the flip chip method, the flux 5 is transferred or supplied to the surface of the solder bump 3 and / or the substrate electrode 4 in advance, and the adhesiveness of the flux 5 is used to make the chip 1. Temporary fixing after mounting. In the reflow heating, the chip 1 is mounted on the substrate 2 and then placed in a reflow furnace (not shown) to melt the solder bump 3, the solder bump 3 and the substrate electrode 4 are joined, and then cooled to be solder bump 3. The process of completing the joining is followed by solidifying.

  FIG. 3 is a cross-sectional view (A) of the state in which the solder bumps of the chip adsorbed by the bonding head and the substrate electrodes are mounted in the conventional flip-chip method, and the solder is melted by pressing with predetermined heating and load. FIG. 4B is a cross-sectional view (B) of a state where the chip adsorbed by the bonding head is mounted with the position of the solder bump and the substrate electrode aligned, pressed with a predetermined load, and then solder melted by reflow heating. In the flip chip method of FIG. 1A, the solder bumps 3 of the chip 1 adsorbed by the bonding head 6 and the substrate electrodes 4 formed on the substrate 2 are aligned and mounted, and the chip 1 is mounted on the substrate with a predetermined load as it is. 2 is heated by the bonding head 6 to melt the solder bump 3, the solder bump 3 and the substrate electrode 4 are joined, and the bonding head 6 is removed after the solder bump is solidified.

  The main effect of the flux is to temporarily fix the chip after mounting due to the above-mentioned adhesiveness and to remove the oxide film on the solder or non-solder joint surface when the solder is melted and joined, and the solder or non-solder joint surface. It is indispensable when the solder is melted to prevent reoxidation.

  However, since the flux is corrosive, it must be removed after joining, which requires a cleaning process. FIG. 4 is a cross-sectional view showing a state after the flux is removed by a cleaning process in the conventional flip chip method. Also, after removing the flux, it is common to fill the resin between the chip 1 and the substrate 2. FIG. 5 is a cross-sectional view of a state in which a thermosetting resin is filled between the chip and the substrate, but in order to reinforce the bonding strength between the chip 1 and the substrate 2 and improve the reliability of the product, The filling of an underfill resin such as a thermosetting resin 7 between the chip 1 and the substrate 2 was an essential condition. The thermosetting resin 7 is supplied by the dispenser 8 or the like, but there is a problem that the resin injection is hindered by the residue of the flux 5 and the filling becomes difficult. Further, the flux residue has poor adhesion to the thermosetting resin 7 injected after joining, and thus may cause peeling, which is a factor of reducing the reliability of the manufactured product.

  Due to the above problems, a cleaning process for completely removing the flux 5 is necessary. When performing flux cleaning for flip chip mounting, the distance between the chip 1 and the substrate 2 is about 50 μm, and cleaning is performed between very narrow gaps, and it is necessary to perform cleaning for a long time for complete removal. Yes, it is a factor of cost increase.

  In the above heating method, it takes time to melt the solder due to the entire reflow method, and the bonding method by heating the bonding head can shorten the time until the solder melts due to local heating, but the solder after melting Since the bonding head cannot be separated from the chip until it cools and solidifies, a long tact time is required, which increases costs.

  In order to solve such problems, a fluxless flip chip mounting method uses a thermosetting resin having a flux action, and there is also a reflow bonding method, but the thermosetting resin due to the high temperature during reflow. Moisture inside and air entrained in the resin suddenly expands to cause cracks, or when entering the reflow furnace, the thermosetting resin is not cured and is liquid, so the chip holding power is weak There is a problem that the tip position shifts due to hot air in the reflow furnace. (For example, see Patent Document 1)

JP 2001-284382 A

  Cost increase due to long tact time due to reflow method and bonding head heating method. Corrosion due to the flux used when mounting the chip by the flip-chip method or deterioration of product reliability. Cost increase problem due to long cleaning time when performing flux cleaning process between narrow gap after bonding chip and substrate. Inhibition of thermosetting resin injection due to flux residue after cleaning. Reliability degradation due to adhesion between flux residue and thermosetting resin. An object of the present invention is to solve the problem of joining tact, the problem due to the use of flux, the problem related to the injection of thermosetting resin, and the problem of lowering reliability.

  The invention of the chip bonding method according to claim 1 includes at least a step of supplying a thermosetting resin to a substrate in advance, a step of supplying a chip on the thermosetting resin, and local heating by a non-contact heat source. A chip bonding method comprising a step of heating the chip to melt solder bumps and bonding to an electrode on a substrate.

  An invention of a chip bonding method according to claim 2 is the chip bonding method according to claim 1, further comprising a step of curing the thermosetting resin in claim 1.

  The invention of a chip bonding apparatus according to claim 3 includes at least means for positioning and mounting a substrate to which chips are supplied, non-contact heating means for locally heating a semiconductor mounting portion of the substrate, and the heating A chip bonding apparatus comprising means for controlling the means.

  According to a fourth aspect of the present invention, there is provided a chip bonding apparatus according to the third aspect, further comprising means for supplying a thermosetting resin and means for supplying a chip.

  The invention of a chip bonding apparatus according to claim 5 is the invention according to claim 4, wherein, before supplying the chip, an alignment recognition function for aligning the position of the solder bump and the substrate electrode, and when supplying the chip, A chip bonding apparatus comprising means for controlling a mounting load for extruding a thermosetting resin interposed between a solder bump and a substrate electrode.

  According to a sixth aspect of the present invention, there is provided the chip bonding apparatus according to any one of the third to fifth aspects, wherein at least the means for supplying the thermosetting resin, the means for supplying the semiconductor with solder bumps, and the semiconductor mounting are provided. A semiconductor bonding apparatus with solder bumps, characterized in that means for locally heating the mounting portion has means for continuously flowing to the next process on the same transport system.

  According to the chip bonding method of the invention of claim 1, since the chip is locally heated by a non-contact heat source on the chip mounted by the adhesiveness of the thermosetting resin supplied to the substrate in advance, in a short time Since the temperature rises to the solder melting point, melting and joining are performed, and non-contact local heating, the waiting time until the solder cools and solidifies becomes extremely short. Compared with the conventional reflow method and bonding head method, the bonding time can be shortened, and the problem of cost increase due to a long bonding time can be solved. Moreover, since the flux cleaning process can be omitted and the process can be simplified, it is possible to solve the problem of cost increase caused by performing the cleaning process. Furthermore, the solder melt bonding is performed with non-flux, so that it is possible to solve the problem of deterioration of product reliability due to corrosion or peeling due to flux. Since the thermoplastic resin is supplied in advance, there is no possibility of hindering injection of the thermosetting resin due to the flux residue, which is a problem of the prior art.

  According to the chip bonding method of the invention of claim 2, the thermosetting resin that has been semi-cured at the time of melt bonding is cured after bonding, so that the thermosetting resin is fully cured and the reliability of the product is improved. I can do it.

  Since the chip bonding apparatus of the invention of claim 3 has means for locally heating the chip with a non-contact heat source on the chip mounted by the adhesiveness of the thermosetting resin supplied to the substrate in advance, The temperature rises to the solder melting point over time, and melting and joining are performed. Because of non-contact local heating, the waiting time until the solder cools and solidifies becomes extremely short. Compared to the conventional reflow method and bonding head method, the bonding time can be shortened, and the production capacity of the bonding device can be improved compared to a device that requires a long bonding tact time. In addition, the flux cleaning step that is conventionally required in the post-process can be omitted, and the process can be simplified, so that the problem of cost increase due to the cleaning process can be solved. Furthermore, since solder fusion bonding can be performed with non-flux, it is possible to solve the problem of deterioration in product reliability due to corrosion or peeling due to flux. Because of local heating, the moisture in the thermosetting resin and the air entrained in the resin rapidly expand due to high temperatures, causing cracks, and hot spots in the reflow oven do not cause problems such as chip position shifting. And so on.

  According to the chip bonding apparatus of the fourth aspect of the present invention, the chip supplied on the substrate flows to the solder melting process which is the next process by further including means for supplying the thermosetting resin and means for supplying the chip. Therefore, there are no problems such as chip position shift due to external impact between product movements and moisture absorption due to leaving the resin for a long time. In addition, it is possible to perform thermosetting resin supply, chip supply, and solder fusion bonding with the same apparatus, thereby reducing personnel.

  According to the chip bonding apparatus of the fifth aspect of the present invention, it is possible to always supply the chip at an accurate position by further having a position recognition function for aligning the solder bump portion of the chip and the substrate electrode position. Also, by having a mounting weight control function, mounting can always be performed with an appropriate weight, and the resin between the bump and the substrate electrode cannot be pushed out due to chip breakage due to overloading or insufficient weighting. It is possible to prevent the unbonded problem caused by the failure.

  According to the chip joining apparatus of the invention of claim 6, each of the thermosetting resin supply means, the chip supply means, and the local heating means by non-contact to the chip has a function of being able to be performed in the same transport system. Since the process is performed on the same transport system and the flow to the next process is continuous, the thermosetting resin supply means, the chip supply means, and the local heating means by non-contact to the chip can be performed by one worker. This makes it possible to reduce personnel and improve work efficiency.

  Chip joining, comprising: a step of supplying a thermosetting resin to a substrate in advance; a step of supplying a chip; and a step of locally heating with a non-contact heat source to melt and bond the solder Is the method.

    FIG. 1A is a top view (A) and a side view (B) in which a substrate and a chip according to the present invention are overlaid, and (A) is a perspective view of substrate electrodes and solder bumps in the overlaid portion. In (B), the substrate is separated from the chip. Twelve solder bumps 3 are formed on the chip 1, and 12 substrate electrodes 4 corresponding to the solder bumps 3 are formed on the substrate 2.

  FIG. 6 is a schematic view of a state in which a thermosetting resin chip bonding apparatus is supplied onto a substrate. It is desirable that the thermosetting resin (for example, epoxy resin) 7 is supplied so that the substrate electrode 4 part in contact with the solder bumps 3 is completely covered, and the supply means is a general-purpose means such as a dispenser 8 or transfer. The supply amount is preferably such that when the chip 1 is mounted, a fillet can be formed on the side surface of the chip 1 to about half the thickness of the chip 1. It goes without saying that the air entrained in the thermosetting epoxy resin 7 suddenly expands to cause cracks and the position of the chip 1 is not displaced due to buoyancy caused by the thermosetting epoxy resin 7. .

  Regarding the resin physical properties of the thermosetting epoxy resin 7 to be used, when the chip 1 is mounted, it is thermally cured by irradiation heat so as not to cause a positional shift and when local heating only in the vicinity of the chip 1 is performed. In order to suppress scattering of the conductive epoxy resin 7, a resin having a certain degree of viscosity (about 10 Pa.s) is desirable. Further, when the gelation of the thermosetting epoxy resin starts upon heating and hardens before the solder bumps 3, the chip 1 may not be able to be tilted and connected, so the gel time (at 150 ° C.) is increased. The thing of 100 sec-120 sec is desirable.

  FIG. 7 is a cross-sectional view of a state where a chip adsorbed by a bonding head is mounted on a substrate supplied with a thermosetting epoxy resin with the positions of solder bumps and substrate electrodes aligned and pressed with a predetermined load. The bonding weight at this time is preferably about 40 to 50 gf / bump so as to extrude the thermosetting epoxy resin 7 interposed between the solder bump 3 and the substrate electrode 4.

  FIG. 8 is a schematic view showing a state in which a chip mounted with a non-contact heat source (for example, a halogen lamp, a xenon lamp, a laser beam, etc.) is spot-heated and soldered to be joined. It is desirable that the irradiation time at this time be as short as possible so that curing of the thermosetting epoxy resin 7 does not start (preferably within about 2 sec), and a temperature at which the solder bump 3 can be melted within the irradiation time. It is necessary to adjust the power of the non-contact heat source to reach.

  FIG. 9 is a cross-sectional view of a state where the thermosetting epoxy resin is cured under predetermined curing conditions. Post cure under the conditions recommended by the manufacturer of the thermosetting epoxy resin used to cure the resin.

  In this embodiment, a glass epoxy having an outer shape of 5 × 5 mm and a thickness of about 0.5 mm is used as the substrate material. However, the substrate material to be used is formed with substrate electrodes and the like to which solder bumps are joined with an outer shape of about 2 × 2 mm or more. Any ceramic, FPC, glass, or resin substrate can be similarly bonded. In addition, a small chip of about 2 × 2 mm was used for the chip, but local heating due to the size of the chip can be achieved by adjusting the height of the non-contact local heating source and adjusting the focal range. Overheating can be obtained. Note that if the focal range is expanded, the heating temperature also decreases, so the power of the non-contact heat source must be increased. When the chip becomes smaller, there is a limit to the minimum focal range of the non-contact heat source. Therefore, when the chip size is smaller than 2 × 2 mm, a hole of the same size as the chip size is formed on the irradiated chip. It is necessary to install a metal mask or the like, forcibly reduce the focal range by the mask hole, and perform irradiation. As for the type of solder bump to be used, even those having different melting temperatures, such as eutectic solder and lead-free solder, can be joined. The heating temperature at that time is 10 to 20 at a predetermined melting temperature of each solder bump. What is necessary is just to perform melt bonding by irradiating a temperature plus about ℃. Although a halogen lamp is used as a non-contact heat source, any heat source capable of rapid heating without contact, such as a xenon lamp or a laser beam, can be applied to the chip bonding method and the chip bonding apparatus of the present invention.

  FIG. 10 is a schematic view of a chip bonding apparatus according to the present invention. The chip bonding apparatus includes at least a unit (A) for supplying the thermosetting epoxy resin 7 on the substrate 2, a unit (B) for supplying the chip 1 on the substrate 2, and a non-contact on the supplied chip 1. It is comprised by the unit (C) which performs local heating in (4), and is a mechanism which can perform each process with the same conveyance system 10 (for example, belt conveyor). The supply part of the thermosetting epoxy resin 7 of the unit (A) can be performed by a dispenser, and the supply is performed so as to cover all the parts of the substrate electrode 4 that the solder bump 3 contacts. The chip supply unit of the unit (B) is a mechanism 11 having a function of recognizing the position of the solder bump 3 and the substrate electrode 4 and a function of controlling the weight, and supplies the power at a predetermined chip position and mounting weight. . The non-contact local heating unit of the unit (C) unit has a mechanism capable of controlling the heating amount and a height adjusting mechanism 12 for adjusting the focal point, and controls the amount of heat and the heating range and has already been supplied. Local heating is performed on the chip 1. Each unit is performed on the same transport system 10 and has a structure that allows all processes to proceed simultaneously and to automatically flow to the next process.

A top view (A) and a side view (B) in which a substrate and a chip according to the present invention are overlaid. Sectional view of the state in which flux is supplied onto the solder bump portion of the chip and the substrate electrode in the conventional flip chip method In the conventional flip chip method, the solder bumps of the chip adsorbed by the bonding head and the substrate electrodes are mounted at the same position, and a cross-sectional view (A) in which the solder is melted by pressing with predetermined heating and load, and bonding A cross-sectional view (B) of a state where the chip adsorbed by the head is mounted with the solder bump and the substrate electrode aligned, pressed with a predetermined load, and then melted by reflow heating. Cross-sectional view of the state after flux is removed by the cleaning process in the conventional flip chip method Cross-sectional view of a state where a thermosetting resin is filled between the chip and the substrate Schematic diagram of a state where a thermosetting resin chip bonding device is supplied on a substrate Cross-sectional view of a state where a chip adsorbed by a bonding head is mounted on a substrate supplied with a thermosetting epoxy resin with the solder bumps and substrate electrodes aligned, and pressed with a predetermined load Schematic diagram showing a state where a chip mounted with a non-contact heat source is spot-heated and soldered to be joined. Cross-sectional view of a state where thermosetting epoxy resin is cured under specified curing conditions Schematic diagram of a chip bonding apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chip 2 Board | substrate 3 Solder bump 4 Board | substrate electrode 5 Flux 6 Bonding head 7 Thermosetting (epoxy) resin 8 Dispenser 9 Non-contact heat source 10 Conveyance system 11 The mechanism 12 with the alignment recognition function and the load control function 12 Height Adjustment mechanism

Claims (6)

  At least a step of supplying a thermosetting resin to a substrate in advance, a step of supplying a semiconductor with solder bumps on the thermosetting resin, and heating the semiconductor with solder bumps by local heating with a non-contact heat source A semiconductor bonding method with solder bumps, comprising a step of melting a bump and bonding to an electrode on a substrate.   2. The semiconductor bonding method with solder bumps according to claim 1, further comprising a step of curing the thermosetting resin.   It comprises at least means for positioning and mounting a substrate supplied with a semiconductor with solder bumps, non-contact heating means for locally heating a semiconductor mounting portion of the substrate, and means for controlling the heating means. Semiconductor bonding equipment with solder bumps.   4. The semiconductor bonding apparatus with solder bumps according to claim 3, further comprising means for supplying a thermosetting resin and means for supplying a semiconductor with solder bumps.   Furthermore, before supplying the semiconductor with solder bumps, an alignment recognition function for aligning the positions of the solder bumps and the substrate electrodes, and when supplying the semiconductor with solder bumps, intervene between the solder bumps and the substrate electrodes. 5. The semiconductor bonding apparatus with solder bumps according to claim 4, further comprising means for controlling a mounting load for extruding the thermosetting resin.   At least means for supplying a thermosetting resin, means for supplying a semiconductor with solder bumps, and means for locally heating the semiconductor mounting portion have means for continuously flowing to the next process on the same transport system. The semiconductor bonding apparatus with a solder bump according to claim 3, wherein the semiconductor bonding apparatus has a solder bump.

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