JP2004172612A - Semiconductor element having bump with small diameter, bump formation by inkjet method, and ink composite used therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a semiconductor element having a solder bump with a small diameter, which can not be conventionally formed and sufficiently satisfies functions expected to a solder bump; a semiconductor element with a solder bump having reduced voids or cracks; and a semiconductor element with a solder bump formed therein in which separation from an intermediate metal layer or a pad is not generated, and also to provide a method for forming the solder bump in which working time is remarkably reduced, and an ink composite for solder-bump formation used in the method. <P>SOLUTION: The semiconductor element has an intermediate metal layer and a bump sequentially formed on an outer electrode pad, wherein diameter of the bump is not more than 30μm. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a bump forming method using an ink jet method, an ink composition for forming a bump, and a semiconductor element. For example, protruding electrodes (so-called bumps) are formed on a plurality of bump forming positions formed on a bump forming object using an ink jet method. The present invention is suitable for use in a bump forming method, a bump forming ink composition used for forming the bump, and a semiconductor element in which the bump is formed by the bump forming method.

In the bump formation method, as a bump formation target, for example, a wafer in which a plurality of circuits (hereinafter referred to as IC circuits) corresponding to an IC (Integrated Circuit) chip is formed on each IC circuit by the following procedure. Bumps are respectively formed on the plurality of external electrodes (pads) formed.
That is, first, the peripheral edge of each pad made of aluminum or the like of each IC circuit formed on one surface of the wafer is covered with a passivation film to be electrically protected. Next, a positive-type or negative-type photoresist film is laminated on one surface of the wafer, the photoresist film is exposed according to each pad, and then developed to expose each pad. Subsequently, the wafer is loaded into a sputtering apparatus, and a BLM (Ball Limiting Metal) film layer that can improve the adhesion between the pads and the bumps is formed on one surface of the wafer by sputtering.
The BLM film layer is formed by sequentially laminating an adhesive layer made of chromium (Cr) or the like and a barrier metal layer (or barrier layer) made of copper (Cu) or the like to form an intermediate metal layer or Cr / Cu / Also called Au.

Thereafter, the photoresist film formed on one surface of the wafer is peeled off, and the BLM film layer laminated on the photoresist film is removed. As a result, a BLM film layer is laminated on each pad of the wafer.
Next, a photoresist film is formed again on one surface of the wafer, the photoresist film is exposed according to each BLM film layer, and then developed to expose each BLM film layer. Thereafter, bumps are formed on one surface of the wafer by a plating method, a vapor deposition method, or a printing method (in the case of the printing method, a metal mask having an opening corresponding to each BLM film layer is used instead of the photoresist film). Laminate materials. Thereafter, the photoresist film laminated on one surface of the wafer is peeled off, and the bump material laminated on the photoresist film is removed. Thereby, a bump material is laminated on each BLM film layer.
The bump material is formed by sequentially laminating lead and tin. When the entire weight of the bump material is 100%, the weight of the lead is selected in advance so as to be an arbitrary ratio of 90 to 98%. In addition, the weight of tin is selected in advance so as to be an arbitrary ratio of 10 to 2% according to the weight of lead.

  Subsequently, a flux is applied to one surface of the wafer by a predetermined application means. Thereafter, the wafer is heated at a predetermined temperature in a nitrogen atmosphere in a heating and melting furnace to melt lead and tin of the bump material, thereby synthesizing these lead and tin to form solder. At this time, the solder is collected into a spherical shape by the surface tension and the action of the flux in the molten state. Thus, bumps made of spherical solder can be formed on each pad of each IC circuit formed on the wafer via the BLM film layer.

By the way, in such a bump forming method, first, when a BLM film layer is formed on each pad of a wafer (hereinafter referred to as a BLM film layer forming step), a photoresist is used as described above. A film formation process and a photoresist film peeling process are necessary. The number of wafers that can be loaded into the sputtering apparatus at one time is about 3 to 5. For this reason, in the BLM film layer formation process, the said process became complicated and there existed a problem which requires a lot of work time.
In the photoresist film peeling step, 99% or more of the BLM film layer with respect to the whole weight of the BLM film layer laminated on one surface of the wafer is removed together with the photoresist film. Therefore, most of the plurality of types of metal materials used for the BLM film layer laminated on one surface of the wafer are wasted, and there is a problem that the cost increases.

Further, chromium used in the BLM film layer is a metal material harmful to the human body. Further, when the photoresist film is peeled from one surface of the wafer, a strong alkaline solution and an organic solvent harmful to the human body are used. For this reason, in the BLM film layer formation process, a work environment in which the worker can work safely and some kind of equipment are required, and a waste liquid treatment equipment that can safely treat the waste liquid of strong alkaline solution and organic solvent is necessary. There was a problem that the facilities became complicated.
Furthermore, in the step of removing the photoresist film, the photoresist film may not be completely removed and may remain slightly on the passivation film. As described above, when the photoresist film on the passivation film remains, bump materials are formed on the respective BLM film layers, and when these bump materials are heated and melted, the remaining photoresist is formed on the passivation film. There was a burning problem.

On the other hand, in this bump forming method, when a bump material is laminated on each BLM film layer (hereinafter referred to as a bump material forming process), the same as in the above-described BLM film layer forming process. A photoresist film (or metal mask) forming step and a photoresist film (or metal mask) peeling step are necessary. Therefore, the bump material forming process has a problem that the process becomes complicated.
Further, in the step of peeling off the photoresist film (or metal mask) in the bump material forming step, the bump material laminated on the one surface of the wafer together with the photoresist film, as in the case of the BLM film layer forming step described above. More than 99% of the bump material is removed with respect to the total weight. For this reason, most of the bump material (that is, lead and tin) laminated on one surface of the wafer is wasted, and there is a problem that the cost increases.
Furthermore, in the step of removing the photoresist film in the bump material forming step, the photoresist film may not be completely removed and may remain slightly on the passivation film. As described above, when the bump material is heated and melted with the photoresist film remaining on the passivation film, the remaining photoresist burns on the passivation film.

  By the way, when the plating method is applied in the bump material forming process, an acid solution, an alkali solution, an organic solvent, or the like harmful to the human body is used in the plating process of the wafer. Therefore, in this case as well, a working environment and some kind of equipment that allows the worker to work safely are required, and a waste liquid treatment equipment that safely treats waste liquids such as acid solutions, alkaline solutions, and organic solvents is required. There was a problem that the equipment of the formation process became complicated.

Further, in this bump material forming step, when the wafer is plated, irregularities are formed by a pre-formed photoresist film on one surface of the wafer. However, in this plating process, the distribution of the plating current depends on the shape of one surface of the wafer, and the plating current may become uneven. Therefore, in this plating process, it becomes difficult to form the bump material lead and tin so as to have a predetermined thickness on one surface of the wafer, and the blending amount of the bump material lead and tin varies. It will be.
For this reason, when flux is applied to the bump material formed on the BLM film layer in this way and heated and melted, the molten lead and tin are non-uniformly synthesized, and bubble defects (hereinafter referred to as “bubble defects”) are formed inside the formed bump. , This is called a void) and cracks occur. In addition, bumps having different sizes are formed, bumps having a distorted shape (hereinafter referred to as irregular-shaped bumps) are formed, and bumps scattered on the passivation film (hereinafter referred to as scattered bumps). ) Is formed, and there is a problem that a bridge is generated due to contact between adjacent bumps.

On the other hand, when the vapor deposition method is applied in the bump material forming step, about 3 to 5 wafers can be loaded into the vapor deposition apparatus at a time. For this reason, there is a problem that a great deal of time is required to form a bump material on the BLM film layer on a plurality of wafers. Further, in this vapor deposition apparatus, one surface of the wafer is caused due to various problems in the structure of the vapor deposition apparatus such that the one surface of the wafer is inclined and loaded with respect to the vapor deposition source (lead and tin). In addition, it may be difficult to form lead and tin as bump materials so as to have a predetermined thickness.
For this reason, as in the case of the plating process described above, the blending amount of lead and tin of the bump material varies, and the bump material thus formed on the BLM film layer is heated and melted to form the bump. Then, the melted lead and tin are non-uniformly synthesized, and there is a problem that voids and cracks are generated inside the bumps. In addition, bumps having different sizes are formed, irregular-shaped bumps are formed, scattered bumps are formed on the passivation film, and adjacent bumps come into contact with each other.

  Further, when a printing method is applied in the bump material forming step, cream solder is printed on each BLM film layer by a squeegee through a metal mask having an opening corresponding to each BLM film layer. However, in this printing method, the amount of cream solder (printing accuracy) printed on each BLM film layer through the opening of the metal mask due to non-uniform spacing between the squeegee and the metal mask, for example. ) Has a problem that varies. For this reason, in this printing method, there was a problem that the reliability with respect to the printing accuracy of the cream solder was lowered. In addition, there is a problem that bridges are generated due to variations in cream solder, such as bumps having different sizes formed, deformed bumps formed, and adjacent bumps contacting each other.

By the way, in this bump forming method, after bumps are formed on each pad of the wafer, flux remaining on one surface of the wafer is cleaned using various organic solvents. For this reason, also in this cleaning process, a work environment and some kind of equipment that enables workers to work safely are required, and waste liquid treatment equipment that can safely treat waste liquids of these various organic solvents is necessary. There was a problem that the equipment of the process became complicated.
As described above, the conventional bump forming method includes a plurality of processes, and if a defect occurs in any one of the processes, the previous processes are all wasted. Therefore, in this bump forming method, there is a problem that the damage caused when a defect occurs is increased in the subsequent process.

  In order to solve the problems as described above, in the bump forming method of forming bumps at a plurality of bump forming positions on the surface of the bump forming object, each bump forming position of the bump forming object on one surface of the substrate. A first step of arranging bumps corresponding to each of the above, a second step of supplying a conductive adhesive on each of the bumps and / or on each of the bump forming positions of the bump forming object, and each of the bumps The base material and the bump forming object are brought into contact with each other so that the corresponding bump forming positions are brought into contact with each other via the conductive adhesive, and each bump and the corresponding bump forming position are positioned. And a fourth step of fixing each of the bumps to a corresponding bump formation position by solidifying the conductive adhesive. And a bump forming method characterized by comprising a fifth step of separating the base material from the bump fixed to each bump forming position of the bump forming object. (See, for example, Patent Document 1).

  Further, as a flux material used for making solder bumps, it contains at least rosin, an activator, and a solvent. Natural rosin, hydrogenated rosin, and 1% to 99% of the total weight of natural rosin and hydrogenated rosin. A solute blended in an arbitrary ratio, an activator that is activated at a predetermined temperature, the natural rosin, the hydrogenated rosin, the solute, and a solvent that dissolves the activator. Solder bumps made using this flux material are proposed to be used, have a smooth luster on the surface, have an ideal spherical shape, and have no voids or cracks inside. Thus, it has been confirmed that there is an effect that the solder alloy does not scatter (see, for example, Patent Document 2).

  In addition, the solder bumps produced have good surface gloss, surface properties and shape, and as a solder bump making flux material that brings about effects such as no scattering of solder alloy during the production process, at least It is proposed to use a rosin, an activator and a solvent containing a component that decomposes and sublimates in a temperature range of 100 ° C. to 300 ° C. and a component that decomposes and activates in a temperature range of 350 ° C. to 400 ° C. (For example, see Patent Document 3).

  However, as a problem that occurs even when such improved flux is used, in the normal bump forming method, bumps are formed on each pad of the wafer and then applied to one surface of the wafer using various organic solvents. The remaining flux is cleaned. For this reason, this cleaning process also requires a work environment and some kind of equipment that enables workers to work safely, and also requires a waste treatment facility that can safely handle the waste liquids of these various organic solvents. There is a problem that the equipment of the process becomes complicated.

Further, the diameter of the bumps produced by the conventional method is about 50 μm, and it has been difficult to mass-produce bumps having a smaller diameter especially at the manufacturing level. This is because the conventional method repeats a complicated process many times, so that the formed bumps are likely to be uneven, and the smaller the diameter, the more likely it is to become uneven, making it difficult to form bumps with a uniform diameter. Furthermore, there is a problem that voids, cracks and irregular shaped bumps are likely to occur in the bumps produced by the conventional method, and that the tendency increases as the bumps become smaller.
In other words, in the conventional method, the smaller the bumps, the tighter the process control, and the final obtained bumps are discarded and most of the raw materials are wasted, and further heat treatment is required. There's a problem.
However, in the Internet society, it is conceivable that further IC integration and high-density mounting will progress in the future, and therefore, the appearance of bumps with a smaller diameter, particularly solder bumps with a diameter of 30 μm or less, is expected in recent years. The reality is that we have reached today without any proposals.
Furthermore, voids and cracks are observed in conventional bumps, and peeling from the intermediate metal layer or pad may occur, which is a problem.

Furthermore, the following five types of tests are usually performed on solder bumps.
(1) Appearance observation of solder bump with metal microscope (2) Cross-sectional observation of bump with SEM (3) Mechanical strength test (Shea test / Tensile strength test)
(4) Detergency test (5) Reliability test in the case where an IC chip is mounted on a wiring board In these tests, bumps produced by the conventional method have many problems as follows.

JP-A-9-205095 (Claim 1, page 4, left column, line 44 to right column, line 7) JP-A-9-10988 (Claim 1, page 3, right column, line 13 to page 6, right column, line 18) JP-A-8-155675 (Claim 1, page 4, right column, line 33 to page 5, line 19)

An object of the present invention is to provide a semiconductor element in which a solder bump having a small diameter, which has been sufficiently impossible to form in the prior art, sufficiently satisfies the functions expected of a solder bump.
Moreover, the subject of this invention is providing the semiconductor element in which the solder bump with few voids or a crack was formed.
Another object of the present invention is to provide a semiconductor element on which solder bumps are formed that do not cause separation from an intermediate metal layer or a pad.
Furthermore, it is providing the solder bump formation method which can shorten working time significantly, and the ink composition for solder bump formation used therefor.

As a result of intensive studies by the inventors in order to solve the above-mentioned problems, the solder alloy material layer and the flux material layer are formed on the intermediate metal layer formed on the external electrode pad of the semiconductor element. In order to form bumps by heating and melting these two layers, the solder alloy material layer and the flux material layer are formed by an ink jet method so that the discharge amount can be easily controlled. It was confirmed that it was effective for producing solder bumps.
It was also confirmed that it is effective to form a conductive adhesive layer by an ink jet method instead of the intermediate metal layer.
Furthermore, when a process performed in a supercritical fluid or subcritical fluid is used when manufacturing an ink composition used in these ink jet systems, the ink stably contains ultrafine particles having a particle diameter of 10 nm or less. It has been confirmed that the composition can be produced and is particularly effective for producing a desired solder bump.

  That is, the above-mentioned problem is (1) “semiconductor element in which an intermediate metal layer and a bump are sequentially provided on an external electrode pad, and the diameter of the bump is 30 μm or less”. (2) “The semiconductor element according to (1) above, wherein the bump diameter is 0.001 to 10 μm”, (3) “The bump diameter is 0.001 to 1 μm. The semiconductor element according to the above item (1) or (2) ”, (4)“ a solder alloy material layer and a flux material in which bumps are formed on an intermediate metal layer by an ink jet method ” The semiconductor element according to any one of (1) to (3) above, wherein the intermediate metal layer is formed by heating and melting the layer ” Formed by inkjet method It is solved by the paragraph (1) to the semiconductor device according to any one of the item (4) ", characterized in that a conductive adhesive layer.

  Further, the above-described problem is (6) “Solder alloy material layer and flux material layer are sequentially formed on the intermediate metal layer formed on the external electrode pad of the semiconductor element, and then the solder alloy material layer. And a flux material layer are heated and melted to form bumps, wherein the solder alloy material layer is formed by an ink jet method ", (7)" Structure of solder alloy material The bump formation as described in (6) above, wherein the ink composition used in the ink jet system is prepared by a production method including a step performed in a supercritical fluid or a subcritical fluid. (Method), (8) The above item (6), wherein the ink composition constituting the solder alloy material contains at least a solder material, an organic solvent, and a wetting agent. (9) “A solder alloy material layer and a flux material layer are sequentially formed on the intermediate metal layer formed on the external electrode pad of the semiconductor element, and then the solder is formed. A method of forming a bump by heating and melting an alloy material layer and a flux material layer, wherein the intermediate metal layer is a conductive adhesive layer, and the conductive adhesive layer is formed by an ink jet method. Bump forming method ”, (10)“ The ink composition constituting the conductive material and used in the ink jet system is prepared by a manufacturing method including a step performed in a supercritical fluid or a subcritical fluid. (11) “The ink composition constituting the conductive material contains at least a conductive material, an organic solvent, and a wetting agent”. The bump forming method according to the item (9) or (10), ”(12)“ a solder alloy on the intermediate metal layer formed on the external electrode pad of the semiconductor element ” A method of forming bumps by heating and melting the solder alloy material layer and the flux material layer after sequentially forming a material layer and a flux material layer, wherein the flux material layer is formed by an ink jet method. (13) The item (12), wherein the ink composition constituting the flux material and used in the ink jet system contains at least a rosin, an activator, and an organic solvent. (14) “Ink composition constituting flux material is at least rosin, activator, organic solvent, polyol, glycol agent. In the flux for bump formation containing tellurium, surfactant and wetting agent, as an activator, there are a component that decomposes and sublimates in a temperature range of 100 ° C. to 300 ° C. and a component that decomposes and activates in a temperature range of 350 ° C. to 400 ° C. The bump forming method according to the above item (12) or (13) ”, (15)“ natural rosin, hydrogenated rosin, natural rosin and hydrogenated rosin ” Solute blended in an arbitrary ratio of 1% to 99% with respect to the total weight of the above, an activator activated at a predetermined temperature, the natural rosin, the hydrogenated rosin, the solute, and the activator A bump forming method according to item (13) or (14) above, (16) “the solute is a synthetic resin, natural rubber, or synthetic rubber” Or blend single or multiple elastomers The bump forming method according to any one of (13) to (15) ”, (17)“ Ink composition constituting the solder material, and constituting the flux material ” Of the ink composition and the ink composition constituting the conductive material, the viscosity of the ink composition is 1 to 20 mPa · s, the surface tension is 20 to 70 mN / m, and the material constituting the nozzle surface of the inkjet head. The bump forming method as described in any one of (6) to (16) above, wherein the contact angle is 30 to 170 °, (18) “Ink composition constituting the solder material” The viscosity of at least one of the ink composition constituting the flux material and the ink composition constituting the conductive material is 5 to 20 mPa · s, and the surface tension is Bump formation according to any one of (6) to (17), characterized in that the contact angle with respect to the material constituting the nozzle surface of the inkjet head is 5 to 50 mN / m, and 30 to 70 °. Method ”, (19)“ Solid content concentration of at least one of the ink composition constituting the solder material, the ink composition constituting the flux material, and the ink composition constituting the conductive material is high. The bump forming method according to any one of items (6) to (18), characterized in that the composition is 0.01 to 10.0 wt%. (20) “Ink composition constituting the solder material” At least one of the ink composition, the ink composition constituting the flux material, and the ink composition constituting the conductive material has a low vapor pressure of 0.001 to 50 mmHg (room temperature). The problem is solved by the bump forming method according to any one of (6) to (19), which includes at least one kind of solvent.

  In addition, the above-mentioned problem is solved by (21) “a bump characterized by being formed by the method according to any one of (6) to (20)”.

  Further, the above-mentioned problem is (22) “Solder alloy material layer and flux material layer are sequentially formed on the intermediate metal layer formed on the external electrode pad of the semiconductor element, and then the solder alloy material layer. And a step of forming a solder alloy material layer by an ink jet method and forming a bump by heating and melting the flux material layer and performing in a supercritical fluid or a subcritical fluid. An ink composition constituting a solder alloy material characterized by being produced by a manufacturing method ”, (23)“ At least a solder alloy material, an organic solvent, and a wetting agent ”. 22) Ink composition constituting solder alloy material according to item ”, (24)“ Solder alloy on intermediate metal layer formed on external electrode pad of semiconductor element ” After forming the material layer and the flux material layer in sequence, the conductive adhesive layer, which is an intermediate metal layer, is formed by the inkjet method when the bump is formed by heating and melting the solder alloy material layer and the flux material layer. An ink composition constituting a conductive material, characterized in that it is produced by a production process including a process carried out in a supercritical fluid or subcritical fluid, ”(25)“ At least conductive (26) “Ink composition constituting conductive material according to item (24)”, comprising “conductive material, organic solvent, wetting agent”, (26) “formed on external electrode pad of semiconductor element” A solder alloy material layer and a flux material layer are sequentially formed on the intermediate metal layer, and then the solder alloy material layer and the flux material layer are heated and melted to form bumps. An ink composition constituting a flux material, which is used to form a flux material layer by an ink jet method and contains at least rosin, an activator, and an organic solvent ”, (27)“ At least rosin , Active component, organic solvent, polyol, glycol ether, surfactant, wetting agent containing flux forming component that decomposes and sublimates in the temperature range of 100 ° C to 300 ° C and 350 ° C to 400 ° C as the active agent (28) “Natural rosin, hydrogenated rosin, and an ink composition constituting the flux material according to the above item (26)”, which contains a component that decomposes and activates in a temperature range of A solute blended in an arbitrary ratio of 1% to 99% with respect to the total weight of the natural rosin and the hydrogenated rosin, and an activity activated at a predetermined temperature. Item (26) or Item (27), comprising a sex agent, a solvent for dissolving the natural rosin, the hydrogenated rosin, the solute, and the active agent. In the above item (28), the ink composition constituting the flux material ", (29)" the solute is composed of a synthetic resin, natural rubber, synthetic rubber or elastomer alone or in combination. At least one of the ink composition constituting the solder material, the ink composition constituting the solder material, the ink composition constituting the flux material, and the ink composition constituting the conductive material. The viscosity of one ink composition is 1 to 20 mPa · s, the surface tension is 20 to 70 mN / m, and the contact angle to the material constituting the nozzle surface of the inkjet head is 30 to 170 °. The ink composition according to any one of Items (22) to (29), which is characterized by (31) “Ink composition constituting the solder material, Ink composition constituting the flux material,” Item (22) to Item (30), wherein the solid content concentration of at least one of the ink compositions constituting the conductive material is 0.01 to 10.0 wt%. At least one of the ink composition constituting the solder material, the ink composition constituting the flux material, and the ink composition constituting the conductive material. 32. The ink composition according to any one of items (22) to (31), wherein the ink composition contains at least one solvent having a vapor pressure of 0.001 to 50 mmHg (room temperature). It is solved by.

  According to the present invention, a solder alloy material layer and a flux material layer are sequentially formed on an intermediate metal layer formed on an external electrode pad of a semiconductor element by an ink jet method, and then bumps are formed by heating and melting. According to the method, it is possible to realize a bump forming method that can easily and quickly form bumps at a lower cost than conventional bump forming methods, and thus can significantly reduce the working time in the bump forming process.

Moreover, the complicated process and solvent processing process which produce the intermediate metal layer until now became unnecessary by forming a conductive contact bonding layer with an inkjet system instead of an intermediate metal layer. Furthermore, an ink composition for forming a solder alloy layer, an ink composition for forming a flux layer, and an ink for forming a conductive adhesive layer, which are excellent in ejection properties, patterning properties, and film forming properties, using a supercritical fluid or subcritical fluid process A composition could be provided.
In addition, by using the ink composition, bump formation can be easily and easily patterned at low cost by the inkjet method compared to the conventional bump formation method, thus greatly reducing the work time in the bump formation process. The method could be realized.
Furthermore, it was possible to form a bump having excellent characteristics with a bump diameter of 10 μm or less, 5 μm or less, or 1 μm or less, which has been difficult to produce.

In addition, in the flux ink composition for forming solder bumps by the ink jet method of the present invention, as an activator, a component that decomposes and sublimates in a temperature range of 100 ° C. to 300 ° C. and decomposes and activates in a temperature range of 350 ° C. to 400 ° C. Contains ingredients.
And among the said active agents, the effect which improves surface properties, such as decomposition | disassembly sublimation in the temperature range of 100 to 300 degreeC, removal of the oxide film of the surface of a solder alloy material, improvement of solderability, provision of surface glossiness, etc. For example, an organic acid activator that does not leave a residue is included as a component to be exhibited, and it decomposes and activates in a temperature range of 350 ° C. to 400 ° C. to remove voids inside the bump, to prevent solder alloy scattering, or solder As a component that exhibits an effect of uniformly melting the alloy materials, for example, a halogen compound-based activator that remains is included, and the organic acid-based activator is 0.01% by weight to the solder bump forming flux solid content. It is contained at a rate of 10% by weight, and the halogen compound-based activator is contained at a rate of 0.01% by weight to 10% by weight in the solid content of the solder bump forming flux ink composition. Therefore, when the solder bump is formed, the organic acid activator exerts an effect on the surface property and shape of the solder bump at the time of preheating in a temperature range of 100 ° C. to 300 ° C., and 350 ° C. to 400 ° C. Halogen compound-based activator has an effect on solder bump formation during main heat in the temperature range, and the solder bumps are formed satisfactorily by satisfying the functions expected when forming solder bumps. Will improve.

  In addition, in the flux ink composition for forming solder bumps by the ink jet method of the present invention, among the active agents, decomposition and sublimation in the temperature range of 100 ° C. to 300 ° C. to remove the oxide film on the surface of the solder alloy material, solderability That contains at least a surfactant as a component that exhibits the effect of improving the surface properties such as improving the surface gloss and imparting surface gloss, and decomposes and activates in the temperature range of 350 ° C. to 400 ° C. to remove voids inside the bump. Since at least a surfactant is included as a component that exhibits the effect of preventing the alloy from scattering or melting the solder alloy materials uniformly, the temperature ranges from 100 ° C. to 300 ° C. and 350 ° C. to 400 ° C. From preheat to main heat, the above surfactants have an effect on the surface properties and shape of solder bumps. Exert effect on the formation, the solder bumps sufficiently satisfy the functions expected in forming a solder bump satisfactorily formed, productivity is improved.

  A natural rosin, a hydrogenated rosin, a solute blended in an arbitrary ratio of 1% to 99% with respect to the total weight of the natural rosin and the hydrogenated rosin, and an activator activated at a predetermined temperature. Can be used in high temperature conditions such as wet-back processing, and the solder can satisfy the functions expected when forming solder bumps. Bumps are formed well and productivity is improved.

  In addition, in the bump forming method according to the embodiments described later, the amount of flux used is very small that is only ejected by the ink jet method, so that waste liquid treatment equipment for treating waste liquid such as an organic solvent used in the cleaning process can be easily obtained. The bump forming process can be further simplified.

That is, the semiconductor element of the present invention is characterized in that the diameter of the solder bump is 30 μm or less, which has been impossible to manufacture by the conventional method, and the solder bump has few voids and cracks. Further, it is characterized in that it does not peel off from the intermediate metal layer or the pad.
According to the method for forming a solder bump of the present invention, a solder bump having a diameter of 30 μm or less can be formed. As a solder bump of a semiconductor element, 0.001 to 10 μm is preferable, and further 0.1 to 1 μm. Those having diameters are effective, and those having such diameters can be formed by the solder bump forming method of the present invention.
The method of forming the solder bump of the present invention having such a feature is not limited, but as described above, the present inventors have realized by adopting the ink jet method, and the formation of the solder bump. According to the investigation by the present inventors, there has been nothing in the past regarding adopting an ink jet method as a method.
Furthermore, it is desirable that the ink composition used in the ink jet system stably contains ultrafine particles having a uniform particle diameter, and as described above, a supercritical fluid or a subcritical fluid is particularly preferable for that purpose. By using an ink composition that has been confirmed and formed in such a manner, formation of a desired solder bump by an ink jet method can be realized particularly easily.
Hereinafter, the solder bumps of the present invention will be described sequentially with a focus on the formation method.

In the method for forming a solder bump of the present invention, it is particularly effective to use the following ink compositions (1) to (3).
(1) An ink composition containing a conductive material, a solder material, or a flux material, which is applied by an inkjet method in a bump forming method, having a viscosity of 1 to 20 mPa · s, a surface tension of 20 to 70 mN / m, An ink composition having a contact angle with a material constituting a nozzle surface of an inkjet head of 30 to 170 °.
According to the ink composition of (1), particularly when applied by the ink jet method, the nozzle hole is clogged, the flying bend of the ink droplet is suppressed, the discharge is smoothed, and the discharge amount and the discharge timing can be controlled. Thus, stable ejection by the ink jet method becomes possible.
In particular, in order to obtain such an effect, at least one of the ink composition constituting the solder material, the ink composition constituting the flux material, and the ink composition constituting the conductive material is used. It is effective for forming bumps that the viscosity is 5 to 20 mPa · s, the surface tension is 25 to 50 mN / m, and the contact angle to the material constituting the nozzle surface of the inkjet head is 30 to 70 °.
(2) The ink composition according to (1), wherein the solid content concentration is 0.01 to 10.0 wt%.
According to the ink composition (2), it is possible to obtain a desired film thickness without impairing the discharge property when applied by an ink jet method.
(3) The ink composition as described in (1) above, comprising at least one solvent having a vapor pressure of 0.001 to 50 mmHg (room temperature).
According to the ink composition (3), the ink can be prevented from drying when applied by inkjet, and clogging in the nozzle holes can be eliminated.

In particular, as a flux ink composition for forming solder bumps applied by an ink jet method, as an activator in the ink, the surface of the solder alloy material surface removal during preheating, improved solderability, surface gloss, etc. Including a component that exhibits an effect of improving the properties and a component that exhibits an effect of removing the void inside the bump during the main heat, preventing the scattering of the solder alloy, or uniformly melting the solder alloy materials, Alternatively, it has been found that by including a component that exhibits the above effects from preheating to main heating, the solder bump can be satisfactorily formed while sufficiently satisfying the function expected when the solder bump is formed.
Further, natural rosin, hydrogenated rosin, a solute blended in an arbitrary ratio of 1% to 99% with respect to the total weight of these natural rosin and hydrogenated rosin, and an activator activated at a predetermined temperature By providing a solvent that dissolves these natural rosin, hydrogenated rosin, solute, and activator, the solder bump sufficiently satisfies the functions expected when forming a solder bump. Has been found to be well formed.

Furthermore, by containing rosin, activator, organic solvent, polyol, glycol ether, surfactant, wetting agent as the ink composition, the ejection stability as an inkjet ink can be maintained without problems. I found it.
That is, the present invention provides a solder bump forming flux comprising at least a rosin, an activator, and a solvent. As an activator, a component that decomposes and sublimates in a temperature range of 100 ° C. to 300 ° C. It is characterized by containing a component that decomposes and activates within a range.

And as a component decomposed and sublimated in the temperature range of the said 100 degreeC-300 degreeC, the organic acid type activator which a residue does not remain is mentioned, for example, As a component which decomposes and activates in the temperature range of 350 degreeC-400 degreeC, For example, residual halogen compound activator is used, and when these are used, the organic acid activator is contained in the solder bump forming flux solid content in a proportion of 0.01 wt% to 10 wt%. The halogen compound activator is preferably contained in the solder bump forming flux solid content in a proportion of 0.01 wt% to 10 wt%.
At this time, the organic acid activator improves surface properties such as removal of an oxide film on the surface of the solder alloy material, improvement of solderability, and imparting surface gloss during preheating in a temperature range of 100 ° C. to 300 ° C. It is effective.

Further, the halogen compound-based activator has the effect of removing voids inside the bumps, preventing the solder alloy from scattering, or uniformly melting the solder alloy materials during main heating in the temperature range of 350 ° C. to 400 ° C. Is to demonstrate.
If the contents of the organic acid activator and the halogen compound activator are outside the above ranges, it is difficult to exert sufficient effects.
Further, the content of the organic acid activator is more preferably 0.1% by weight to 5% by weight in the solder bump forming flux solid, and the content of the halogen compound activator is solder bump forming. More preferably, it is 0.1 wt% to 5 wt% in the flux solid content.

Furthermore, in the solder bump forming flux of the present invention, when the content of the organic acid activator is M1 and the content of the halogen compound activator is M2, M1: M2 is 1:10 to 10: A range of 1 is preferable.
In the solder bump forming flux of the present invention, the organic acid activator is preferably a linear compound having a molecular weight of 40 to 400 or a cyclic compound having a molecular weight of 80 to 700.
Furthermore, in the solder bump forming flux of the present invention, the halogen compound activator preferably has a molecular weight of 40 to 700.
Specific examples of the organic acid activator in the solder bump forming flux of the present invention include succinic acid, benzoic acid, adipic acid, abitienic acid, glutaric acid, palmitic acid, stearic acid, azelaic acid, formic acid and the like. It is done.

  On the other hand, specific examples of the halogen compound activator include ethylamine hydrochloride, methylamine hydrochloride, ethylamine bromate, methylamine bromate, propenediol hydrochloride, allylamine hydrochloride, 3-amino-1-propene hydrochloride. Salt, N- (3-aminopropyl) methacrylamide hydrochloride, o-anisidine hydrochloride, n-butylamine hydrochloride, p-aminophenol hydrochloride and the like.

Examples of the flux for forming solder bumps of the present invention for achieving the above-described object include the following. That is, among the active agents, at least a surfactant is included as a component that decomposes and sublimates in a temperature range of 100 ° C. to 300 ° C., and at least a surfactant is included as a component that decomposes and activates in a temperature range of 350 ° C. to 400 ° C. It is characterized by being.
At this time, the surfactant removes an oxide film on the surface of the solder alloy material, improves solderability, and imparts surface gloss, from preheating to main heating in the temperature range of 100 ° C. to 300 ° C. and 350 ° C. to 400 ° C. The effect of improving the surface properties such as the above, and the effect of removing voids in the bumps, preventing the solder alloy from scattering, or uniformly melting the solder alloy materials are exhibited.
Specific examples of such surfactants include quaternary ammonium (Lion Corporation: Arcard C-50, Esocard C / 12 (trade name), etc.), lauryltrimethylammonium chloride (Kao Corporation: Cotamine 24P (Product) Name) and the like, and alkylbenzyldimethylammonium chloride (manufactured by Kao Corporation: SANISOL C (trade name), etc.).

Furthermore, in the solder bump forming flux described so far, the boiling point of the solvent is preferably 150 ° C to 300 ° C, and more preferably 220 ° C to 250 ° C.
Specific examples of the solvent having the above boiling point include 2- (2-n-butoxyethoxy) ethanol, 2- (2-n-butoxyethoxy) ethyl acetate, 1,3-butanediol, 1,4- Examples include butanediol and N-methyl-2-pyrrolidone.
In the solder bump forming flux of the present invention described so far, natural rosin and hydrogenated rosin that are almost decomposed and left by preheating and main heating can be used as rosin. Furthermore, you may add resin, a heat stabilizer, antioxidant, a dispersing agent, thickeners, such as a castor oil, etc. as needed.

  The ink composition has a water-soluble organic solvent such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol, 2,3-butanediol, 1, 4-butanediol, 1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, polyethylene glycol, 1,2,4-butanetriol, 1,2, At least one water-soluble selected from 6-hexanetriol, thiodiglycol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone It is preferable to contain an organic solvent Ku, it is possible to suppress drying of ink, it is possible to adjust the ink viscosity to a desired value.

The ink composition contains at least one surfactant selected from acetylene glycol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyethylene-polypropylene copolymers, and fluorine surfactants. In particular, it is possible to improve the wettability and adjust the surface tension to a desired value without impairing the ink discharge performance.
The ink composition preferably contains a diol having 6 or more carbon atoms and an alkyl ether, and can improve the wettability and adjust the surface tension to a desired value without impairing the ink ejection performance. It becomes.
In order to maintain the liquid contact stability of the nozzle plate, the pH of the ink composition is preferably adjusted to 6 or more and 11 or less.

Hereinafter, embodiments of the present invention will be described in detail.
The semiconductor element of the present invention has a bump having a diameter of 30 μm or less.
The bump forming method is not particularly limited as described above, but the present inventors have realized by adopting an ink jet method.
That is, the solder bump having a diameter of 30 μm or less of the present invention is particularly useful for high integration and high density mounting of IC.
According to the ink jet system of the present invention, it is possible to produce a bump having a desired diameter, not limited to 30 μm or less, by controlling the ink discharge amount and the like.

The bump forming method by the inkjet method used in the present invention is a method of sequentially forming a solder alloy material layer and a flux material layer on an intermediate metal layer or a conductive adhesive layer formed on an external electrode pad of a semiconductor element, A method of forming a bump by heating and melting, wherein a solder alloy material layer and / or a flux material layer and / or a conductive adhesive layer is formed by an ink jet method.
According to such an ink jet method, in general, an ink composition with an accurate discharge amount can be controlled and discharged at an accurate position, and in particular, an ultrafine ink composition such as 1 pl can be accurately discharged. Therefore, fine patterning can be performed easily and in a short time. In addition, since a necessary amount of material may be applied to a necessary place, the material is not wasted even if the substrate has a large area.
Furthermore, when the ink composition constituting the solder alloy material or the conductive material used in the ink jet system includes a step performed in a supercritical fluid or a subcritical fluid in at least a part of the step of manufacturing the ink composition, It is particularly effective for obtaining bumps.

  According to the forming method of the present invention having the above-described characteristics, it is possible to form a solder bump having a small diameter, which could not be formed conventionally, that is, a diameter of 30 μm or less, 10 μm or less, or 1 μm or less. Solder bumps can be formed.

The ink composition that constitutes the solder alloy material or the conductive material, and that it can be used in the ink jet system, of course, is the ink composition that constitutes the solder alloy material or the conductive material using a supercritical fluid or a subcritical fluid. There is no conventional manufacturing method.
For reference, a known technique using a supercritical fluid or a subcritical fluid includes an ink containing a dye used for forming an image by an inkjet method, and a photosensitive layer containing a pigment. There is one related to the electrophotographic photosensitive member provided (see, for example, Patent Documents 4 to 8).

JP 2001-172532 A JP 2001-262203 A JP 2002-138229 A JP 2001-92165 A JP 2002-138216 A

<1. Dispersion method of bump forming material by supercritical fluid or subcritical fluid process>
First, a method for manufacturing a bump forming material using a supercritical fluid or a subcritical fluid will be described.
Supercritical fluids or subcritical fluids include hydrocarbons, halogenated hydrocarbons, alcohols, ethers, acetals, ketones, esters, fatty acids, aromatics, nitrogen compounds, and sulfur compounds. Various substances such as a solvent, water, carbon dioxide, nitrogen, and ammonia can be used. Among these, ketone solvents, alcohol solvents, and aromatic solvents are preferable because the bump forming material is a highly soluble substance.

Examples of ketone solvents include acetone, methyl ethyl ketone, isopropyl methyl ketone, isobutyl methyl ketone, 2-pentanone, 3-pentanone, cyclohexanone, and mixed solvents thereof.
Examples of alcohol solvents include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, allyl alcohol, and mixed solvents thereof. Is mentioned.

Further, aromatic solvents include benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, isopropylbenzene, 1,3,5-trimethylbenzene, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene. , P-dichlorobenzene, phenol, o-cresol, m-cresol, p-cresol, benzyl alcohol, anisole, acetophenone, nitrobenzene, benzonitrile, aniline, methyl benzoate, and a mixed solvent thereof.
Of these, acetone, methyl ethyl ketone, methanol, ethanol, 1-propanol, 2-propanol, benzene, and toluene are preferable. These solvents can be used alone or in combination.

In particular, aromatic solvents are often thermally and chemically stable, and are preferably used as supercritical fluids and subcritical fluids because they are less susceptible to thermal decomposition and reaction with solder materials and conductive materials. .
Here, the “supercritical fluid” generally refers to a fluid that is in a state of a critical temperature or higher and a critical pressure or higher. For example, in the case of acetone, it becomes a supercritical fluid under the conditions of a critical temperature of 235 ° C. or higher and a critical pressure of 4.7 MPa or higher.

  Similarly, methyl ethyl ketone is 262 ° C., 4.2 MPa or more, isopropyl methyl ketone is 280 ° C., 3.8 MPa or more, isobutyl methyl ketone is 298 ° C., 3.3 MPa or more, 2-pentanone is 288 ° C., 3.7 MPa or more, 3 -Pentanone is 288 ° C, 3.7 MPa or more, cyclohexanone is 356 ° C, 3.8 MPa or more, methanol is 239 ° C, 8.1 MPa or more, ethanol is 243 ° C, 6.4 MPa or more, 1-propanol is 264 ° C, 5. 2 MPa or more, 2-propanol is 235 ° C., 4.8 MPa or more, 1-butanol is 290 ° C., 4.4 MPa or more, 2-butanol is 263 ° C., 4.2 MPa or more, isobutyl alcohol is 274 ° C., 4.3 MPa or more, tert-Butyl alcohol is 233 ° C., 4.0 MPa or higher, 1- Intanol is 315 ° C., 3.9 MPa or higher, allyl alcohol is 272 ° C., 5.7 MPa or higher, benzene is 289 ° C., 4.9 MPa or higher, toluene is 319 ° C., 4.1 MPa or higher, o-xylene is 357 ° C., 7 MPa or more, m-xylene is 344 ° C., 3.5 MPa or more, p-xylene is 343 ° C., 3.5 MPa or more, ethylbenzene is 344 ° C., 3.6 MPa or more, isopropylbenzene is 358 ° C., 3.2 MPa or more, 1, 3,5-trimethylbenzene is 364 ° C., 3.1 MPa or more, chlorobenzene is 359 ° C., 4.5 MPa or more, o-dichlorobenzene is 424 ° C., 4.1 MPa or more, m-dichlorobenzene is 411 ° C., 3.9 MPa or more , Phenol is 421 ° C, 6.1 MPa or more, o-cresol is 422 ° C, 5.0 MPa Above, m-cresol is 426 ° C., 4.8 MPa or more, p-cresol is 426 ° C., 4.7 MPa or more, anisole is 368 ° C., 4.2 MPa or more, nitrobenzene is ° C., MPa or more, benzonitrile is 426 ° C., 4 .2 MPa or more, aniline 426 becomes a supercritical fluid at a temperature of 5.3 MPa or more, and methyl benzoate becomes a supercritical fluid at 438 ° C. or 4.0 MPa or more.

The “subcritical fluid” generally refers to a fluid in a temperature region lower than the critical temperature.
When using supercritical fluids and subcritical fluids, in order to efficiently dissolve the bump forming material in the supercritical fluid and subcritical fluid, an appropriate solvent (entrainer) is used as the supercritical fluid and subcritical fluid. You may mix and use.
Examples of entrainers include hydrocarbon solvents such as hexane, cyclohexane, benzene and toluene, halogenated hydrocarbon solvents such as methyl chloride, dichloromethane, dichloroethane and chlorobenzene, and alcohol solvents such as methanol, ethanol, propanol and butanol. Ether solvents such as diethyl ether and tetrahydrofuran, acetal solvents such as acetaldehyde diethyl acetal, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate and butyl acetate, formic acid, acetic acid and trifluoroacetic acid Carboxylic acid solvents, nitrogen compound solvents such as acetonitrile, pyridine, N, N-dimethylformamide, sulfur compound solvents such as carbon disulfide and dimethyl sulfoxide, water, nitric acid Such as sulfuric acid, and the like.

The operating temperature range of the supercritical fluid and subcritical fluid is basically not limited as long as it is higher than the temperature at which the bump forming material dissolves, but if the temperature is too low, the supercritical fluid and subcritical fluid of the bump forming material The solubility in the interior may be poor, and if the temperature is too high, the bump forming material may be decomposed. Therefore, the temperature is preferably 10 to 600 ° C., more preferably 20 to 400 ° C.
The working pressure range of the supercritical fluid and subcritical fluid is basically not limited as long as it is higher than the critical pressure of the substance to be used, but if the pressure is too low, the bump forming material enters the supercritical fluid or subcritical fluid. The solubility is sometimes poor, and if the pressure is too high, problems may occur in terms of durability of the production apparatus, safety during operation, and the like.
The device using the supercritical fluid is not limited as long as it has a function of bringing the bump forming material into contact with the supercritical fluid or subcritical fluid and dissolving it in the supercritical fluid or subcritical fluid. For example, it is possible to use a batch system that uses a supercritical fluid or a subcritical fluid in a closed system, a circulation system that circulates and uses a supercritical fluid or a subcritical fluid, and the like.

  The method for precipitating the bump forming material dissolved in the supercritical fluid or subcritical fluid is not limited as long as it is a means for precipitating crystals. For example, the supercritical fluid or subcritical fluid in which the bump forming material is dissolved is used. A method for precipitating crystals by reducing the solubility of the fluid, for example, (I) a method for precipitating crystals by mixing a supercritical fluid or subcritical fluid in which a bump forming material is dissolved with another appropriate solvent, (II) (3) Supercritical fluid or subcritical fluid in which bump forming material is dissolved; (3) Supercritical fluid or subcritical fluid in which bump forming material is dissolved; A method of depositing crystals by changing the pressure only gradually or rapidly without changing the temperature of the critical fluid. (IV) A method of depositing crystals by changing the temperature and pressure of the critical fluid, (V) A supercritical fluid or subcritical fluid in which the bump forming material is dissolved is mixed with another appropriate solvent, and either temperature or pressure is mixed. Alternatively, a method of precipitating crystals by changing both can be used.

Of these, the method of precipitating crystals by changing the temperature is preferable in terms of easy operation and easy control of crystal precipitation conditions.
The temperature at that time is set in consideration of the stability of the bump forming material to heat, etc., but it is preferable to gradually or rapidly lower the temperature to precipitate crystals, and the pressure is constant and only the temperature is set. It is preferable to gradually or rapidly lower the crystal to precipitate crystals.

In addition, in particular, in the method of precipitating crystals by mixing with a solvent, there is a difference in the crystal type and particle size of the bump forming material precipitated depending on the solvent species to be mixed, and the crystal type and particle size can be easily controlled. This is preferable.
Examples of the solvent to be mixed here include water and various conventionally known organic liquid solvents. At the time of mixing, the temperature and pressure of the liquid solvent can be appropriately set according to the manufacturing conditions of the bump forming material, and can be mixed as a supercritical fluid or a subcritical fluid.

Note that the liquid solvent includes a case where a substance that is gaseous at normal temperature and pressure, such as carbon dioxide, is used by liquefaction, and a case where an inorganic salt is dissolved in the liquid solvent. The amount of the solvent mixed with the supercritical fluid or subcritical fluid is preferably 0.1 to 100 times the amount of the supercritical fluid or subcritical fluid.
If the amount of the solvent to be mixed is less than 0.1 times, the mixed solvent hardly has an effect on the crystal conversion and particle size control of the bump forming material.
In addition, when the amount of solvent to be mixed is larger than 100 times, a large amount of solvent is used, so that it takes time to recover the solvent, and the production efficiency is lowered.

FIG. 16 shows a configuration example of a flow-type manufacturing apparatus for manufacturing a bump forming material using a supercritical fluid and a subcritical fluid.
When the bump forming material is crystallized by mixing with a solvent, in FIG. 16, the solvent is sent from a tank (101) containing a solvent used as a supercritical fluid or subcritical fluid by a pump (102). A supercritical fluid or a subcritical fluid is used at the temperature and pressure. The bump forming material previously placed in the container (103) is dissolved in the supercritical fluid or subcritical fluid, and when it passes through the filter (104), it is mixed with the solvent (105) to precipitate crystals.
The obtained crystals of bump forming material are collected (107) through a back pressure valve (106). (108) is a pressure gauge, (109) is a preheating part, (110) is a heat retention part. In addition, in the case where the crystal precipitation of the bump forming material is performed by a temperature change, in FIG. Crystals are precipitated by changing the temperature of the critical fluid or subcritical fluid in the temperature control unit.

<2. Bump-forming ink composition>
In the present invention, the wettability to the pad surrounded by the passivation film can be improved by using the surfactant.
Preferred surfactants include interfacial polyoxyethylene alkyl ether acetates, dialkyl sulfosuccinates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polyoxypropylene block copolymers, and acetylene glycol surfactants. Agents.
More specifically, polyoxyethylene alkyl ether acetate (II) and / or dialkylsulfosuccinic acid (III) having a branched alkyl chain having 5 to 7 carbon chains is selected as the anionic surfactant.

Ｒ：炭素数６〜１４の分岐してもよいアルキル基、ｍ：３〜１２
Ｍ：アルカリ金属イオン、第４級アンモニウム、第４級ホスホニウム、
アルカノールアミン

R: an alkyl group having 6 to 14 carbon atoms which may be branched; m: 3 to 12
M: alkali metal ion, quaternary ammonium, quaternary phosphonium,
Alkanolamine

Ｒ_５、_６：炭素数５〜７の分岐したアルキル基
Ｍ：アルカリ金属イオン、第４級アンモニウム、第４級ホスホニウム、アルカノールアミン

R ₅ , ₆ : branched alkyl group having 5 to 7 carbon atoms M: alkali metal ion, quaternary ammonium, quaternary phosphonium, alkanolamine

Furthermore, by using lithium ions and quaternary ammonium and quaternary phosphonium represented by the following general formula as counter ions of the surfactant of the present invention, the surfactant exhibits excellent dissolution stability.
Preferred nonionic surfactants include those represented by general formula (IV), which is polyoxyethylene alkylphenyl ether, and those represented by general formula (V), which are acetylene glycol surfactants. By using these in combination, permeability can be further improved as a synergistic effect.

Ｒは分岐しても良い６〜１４の炭素鎖
ｋ：５〜１２

R may be branched 6-14 carbon chain k: 5-12

（ｐ、ｑは０〜４０）

(P and q are 0 to 40)

  Ink storage stability can be obtained by setting the pH of the ink composition to 6 or more. However, when the pH is 9 or more, the active agent (III) is likely to change its physical properties due to decomposition during storage, and therefore when using (III), the pH is preferably 6-9.

  The addition amount of (II), (III), (IV) and (V) that can be used in the present invention is between 0.05 to 10% by weight, and the desired penetrability with respect to the ink characteristics required by the printer system. It is possible to give. If it is 0.05% or less, the permeation effect is low, and if it is added in an amount of 10% by weight or more, the compound itself may easily precipitate at a low temperature, resulting in poor reliability.

  Next, the surfactants (II) and (III) used in the present invention are specifically shown in free acid form.

The ink composition of the present invention uses an organic solvent as a liquid medium. In order to make the ink have desired physical properties, to prevent the ink from drying, and to improve the dissolution stability of the compound of the present invention. The following water-soluble organic solvents can be used for the purpose of:
Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,3-purpandiol, 1,3-butanediol, 1,4 butanediol, 1,5 pentanediol, 1,6 hexanediol, glycerol, Polyhydric alcohols such as 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether , Polyethylene alcohol such as diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether Alkyl ethers, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether; N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3 -Nitrogen-containing heterocyclic compounds such as dimethylimidazolidinone and ε-caprolactam; amides such as formamide, N-methylformamide, formamide, N, N-dimethylformamide; monoethanolamine, diethanolamine, triethanolamine, monoethylamine, Examples thereof include amines such as diethylamine and triethylamine, sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and thiodiethanol, propylene carbonate, ethylene carbonate, and γ-butyrolactone. These solvents are used alone or in combination.

  Among these, particularly preferred are diethylene glycol, thiodiethanol, polyethylene glycol 200 to 600, triethylene glycol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, petriol, 1,3 butane. Diol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, N-methyl-2-pyrrolidone, N-hydroxyethylpyrrolidone, 2-pyrrolidone, 1,3 dimethylimidazolidinone, By using these, an excellent effect can be obtained for the high solubility of the present compound and the prevention of poor jetting properties.

In the present invention, pyrrolidone derivatives such as N-hydroxyethyl 2-pyrrolidone are particularly preferable as a solvent for obtaining dispersion stability of rosin.
In addition to the surfactants (II) to (V) of the present invention, penetrants added for the purpose of adjusting the surface tension include diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol mono Alkyl and aryl ethers of polyhydric alcohols such as phenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol chlorophenyl ether, 2-ethyl-1,3-hexanediol, 2,2,4 -Diols such as trimethyl-1,3-pentanediol and 2,2dimethyl1,3-propanediol, polyoxyethylene polyoxypropylene block copolymer Fluorine-based surfactants, lower alcohols such as ethanol and 2-propanol can be mentioned. Particularly preferred are diethylene glycol monobutyl ether as polyhydric alcohol alkyl ether, and 2-ethyl-1,3-hexane as diol having 6 or more carbon atoms. Diol and 2,2,4-trimethyl 1,3-pentanediol. Diols are preferred because they are less likely to cause aggregation of water-insoluble colorants.
The addition amount depends on the type and desired physical properties, but is added in the range of 0.1 wt% to 20 wt%, preferably 0.5 wt% to 10 wt%. If it is less than the lower limit, the permeability is insufficient, and if it is more than the upper limit, the particle formation characteristics are adversely affected.
Also, the addition of these improves the wettability of the ink jet head member and the recording device, improves the filling properties, and makes it difficult for recording defects to occur due to bubbles.

In addition to the colorant and solvent, conventionally known additives can be added to the ink composition of the present invention.
For example, as a preservative and antifungal agent, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, isothiazoline and the like can be used in the present invention.
As the other pH adjusting agent, any substance can be used as long as the pH can be adjusted to 7 or more without adversely affecting the prepared ink.
Examples thereof include amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide and sodium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, Examples thereof include alkali metal carbonates such as lithium carbonate, sodium carbonate, and potassium carbonate.
Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate, and the like.
Examples of the rust preventive include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropyl ammonium nitrite, pentaerythritol tetranitrate, dicyclohexyl ammonium nitrite and the like.
In addition, a water-soluble ultraviolet absorber and a water-soluble infrared absorber can be added depending on the purpose.

<3. Flux ink composition>
In the solder bump forming flux discharged / applied using the ink jet system of the present invention, as an activator, a component that decomposes and sublimates in a temperature range of 100 ° C. to 300 ° C., and decomposes in a temperature range of 350 ° C. to 400 ° C. Contains active ingredients.
And among the said active agents, the effect which improves surface properties, such as decomposition | disassembly sublimation in the temperature range of 100 to 300 degreeC, removal of the oxide film of the surface of a solder alloy material, improvement of solderability, provision of surface glossiness, etc. For example, an organic acid activator that does not leave a residue is included as a component to be exhibited, and it decomposes and activates in a temperature range of 350 ° C. to 400 ° C. to remove voids inside the bump, to prevent solder alloy scattering, or solder As a component that exhibits the effect of uniformly melting the alloy materials, for example, a residual halogen compound-based activator is included, and the organic acid-based activator is 0.01% by weight to the solder bump forming flux solid content. 10% by weight, since the halogen compound activator is contained in the solder bump forming flux solids in a proportion of 0.01% by weight to 10% by weight. When forming solder bumps, the organic acid activator exerts an effect on the surface properties and shape of the solder bumps during preheating in the temperature range of 100 ° C to 300 ° C, and main heat in the temperature range of 350 ° C to 400 ° C. Sometimes a halogenated activator is effective for solder bump formation.

  In the bump forming flux of the present invention, among the active agents, decomposition and sublimation in the temperature range of 100 ° C. to 300 ° C. removes the oxide film on the surface of the solder alloy material, improves solderability, and imparts surface gloss. As a component that exhibits the effect of improving the surface properties, such as at least a surfactant, it decomposes and activates in a temperature range of 350 ° C. to 400 ° C. and removes voids inside the bumps, prevents the scattering of the solder alloy, Alternatively, since at least a surfactant is included as a component that exhibits an effect of uniformly melting the solder alloy materials, from the preheat in the temperature range of 100 ° C. to 300 ° C. and 350 ° C. to 400 ° C. to the main heat, the above The surfactant exerts an effect on the surface property and shape of the solder bump, and also exerts an effect on the formation of the solder bump.

Furthermore, in these solder bump forming fluxes of the present invention, if a solvent having a boiling point of 150 ° C. to 300 ° C. is used, volatilization of the solvent during preheating can be suppressed.
Further, natural rosin, hydrogenated rosin, a solute blended in an arbitrary ratio of 1% to 99% with respect to the total weight of these natural rosin and hydrogenated rosin, and an activator activated at a predetermined temperature Can be improved in heat resistance against high temperature conditions such as wet-back treatment.
Flux uses rosin, activator, solvent, and additive as the basic composition, and further uses a mixture of polyol, glycol ether, surfactant, and wetting agent at a predetermined ratio to impart ink jetting properties. ing.

(1) Rosin The rosin of this example is characterized by using a mixture of natural rosin, hydrogenated rosin and resin. The natural rosin is a mixture of water white rosin (hereinafter referred to as WW (Water White) rosin) having a melting point of about 80 to 90 ° C. and WW rosin having a melting point of about 150 ° C., or pine trees. Hydrogenated rosin is obtained by adding hydrogen to natural rosin.
Furthermore, the resin is formed by blending a single or a plurality of synthetic (polymerized) resin, natural rubber, synthetic rubber, or elastomer. Incidentally, the resin is blended at an arbitrary ratio of about 1 to 99% with respect to the total weight of natural rosin and hydrogenated rosin. This resin enhances the heat resistance of the flux so that the flux can withstand high temperatures in the main heat.

Here, as the synthetic (polymerization) resin, for example, epoxy resin, acrylic resin, polyimide resin, polyamide resin (nylon resin), polyester resin, polyacrylonitrile resin, vinyl chloride resin, vinyl acetate resin, polyolefin resin, fluorine resin, or ABS A resin or a combination of a plurality of resins is used.
As the synthetic rubber, for example, isoprene rubber, styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber, or nylon rubber blended alone or in combination is used.
Further, as the elastomer, for example, a nylon elastomer or a polyester elastomer blended with a single substance or a plurality of elastomers is used.

(2) Activator (related to bump formation characteristics)
As the activator, three types of an organic acid compound that is activated by the preheat of the wet back treatment, a halogen compound that is activated by the main heat, and a surfactant are used. The activator is added to the flux at a ratio of about 0.01 to 10%, preferably about 0.1 to 5%, based on the weight of the solid content contained in the flux. Further, in this activator, an organic acid compound and a halogen compound are blended at an arbitrary ratio of 1 to 10 to 10 to 1, thereby being activated at a wide range of temperatures from preheating to main heating. . Incidentally, as an activator, instead of blending an organic acid compound and a halogen compound, an activator (not shown) capable of exhibiting activity from preheat to main heat may be used alone.

  Actually, for example, succinic acid, benzoic acid, adipic acid, abietic acid, glutaric acid, palmitic acid, stearic acid, formic acid or azelaic acid are used as the organic acid compound. Examples of the halogen compound include ethylamine hydrochloride, methylamine hydrochloride, ethylamine bromate, methylamine bromate, propenediol hydrochloride, allylamine hydrochloride, 3-amino-1-propene hydrochloride, N- (3 -Aminopropyl) methacrylamide hydrochloride, O-anisidine hydrochloride, n-butylamine hydrochloride, P-aminophenol hydrochloride, or the like is used. Furthermore, as an active material that can exhibit an activity from preheat to main heat, for example, quaternary ammonium, lauryltrimethylammonium chloride, alkylbenzyldimethylammonium chloride, or the like is used.

(3) Solvent (for flux characteristics)
As the solvent, a solvent having a boiling point of about 150 to 300 ° C., desirably about 220 to 250 ° C. is selected, and the activator, rosin and the like are dissolved therein. In practice, examples of the solvent include 2- (2-n-butoxyethoxy) ethanol, 2- (2-n-butoxyethoxy) ethyl acetate, 1,3-butanediol, 1,4-butanediol or N-methyl. Use -2-pyrrolidone or the like.

<4. Discharge / application method by inkjet method>
The bump forming method by the inkjet method of the present invention includes a flux material on an intermediate metal layer formed on a pad formed on the surface of a bump forming object and a solder alloy material layer formed thereon. A method of applying the ink composition by an inkjet method, and a method of forming a bump by heating and melting.
In addition, a step of applying an ink composition containing a conductive material to a pad formed on the surface of a bump forming object by an inkjet method to form a conductive adhesive layer, and a solder material on the conductive adhesive layer or the intermediate metal layer A step of applying an ink composition containing an ink composition by an ink jet method to form a solder layer, a step of applying an ink composition containing a flux material thereon by an ink jet method, and a method of forming a bump by heating and melting. Of course, there is no problem.
According to such an ink jet system, fine patterning can be performed easily and in a short time. In addition, since a necessary amount of material may be applied to a necessary place, the material is not wasted even if the substrate has a large area.

An example of the structure of an ink jet head used in the bump forming method of the present invention is shown in FIGS.
The inkjet head (10) includes, for example, a stainless steel nozzle plate (11) and a diaphragm (13), which are joined via a partition member (reservoir plate) (15). Between the nozzle plate (11) and the diaphragm (13), a plurality of ink chambers (19) and a liquid reservoir (21) are formed by the partition member (15).
The interiors of the ink chamber (19) and the liquid reservoir (21) are filled with the ink composition of the present invention, and the ink chamber (19) and the liquid reservoir (21) communicate with each other via the supply port (23). Yes. Further, the nozzle plate (11) is provided with a nozzle hole (25) for ejecting the ink composition from the ink chamber (19) in a jet form.
On the other hand, the ink jet head (10) has an ink introduction hole (27) for supplying an ink composition to the liquid reservoir (21). A piezoelectric element (29) is bonded to the surface of the vibration plate (13) opposite to the surface facing the ink chamber (19) in correspondence with the position of the space (19).

The piezoelectric element (29) is located between the pair of electrodes (31), and bends so that when energized, the piezoelectric element (29) protrudes outward. This increases the volume of the ink chamber (19).
Accordingly, the ink composition corresponding to the increased volume flows into the ink chamber (19) from the liquid reservoir (21) through the supply port (23).
Next, when energization to the piezoelectric element (29) is released, both the piezoelectric element (29) and the diaphragm (13) return to their original shapes. As a result, the space (19) also returns to its original volume, so that the pressure of the ink composition inside the ink chamber (19) rises, and the ink composition is ejected from the nozzle hole (25) toward the substrate.
An ink repellent layer (26) is provided around the nozzle hole (25) in order to prevent the ink composition from being bent or clogged. That is, an ink repellent layer (26) made of, for example, a Ni-tetrafluoroethylene eutectoid plating layer is provided on the periphery of the nozzle hole (25) as shown in FIG.

<5. About physical properties of ink composition>
In the bump forming method of the present invention, an ink composition containing a conductive material, a solder material, or a flux material used by being discharged from the inkjet head has the following characteristics.
The viscosity of the ink composition is preferably 1 to 20 mPa · s, particularly preferably 2 to 8 mPa · s. When the viscosity of the ink composition is less than 1 mPa · s, not only is it difficult to control the ejection amount, but the solid concentration is too low to form a sufficient film. If it exceeds 20 mPa · s, the ink composition may not be smoothly ejected from the nozzle holes, and it may be necessary to change the specifications of the apparatus such as enlarging the nozzle holes. Further, when the viscosity is large, the solid component in the ink composition is likely to precipitate, and the nozzle hole is clogged frequently.

The surface tension of the ink composition is preferably 20 to 70 mN / m, and particularly preferably 25 to 45 mN / m. By setting the surface tension within this range, it is possible to suppress the flight bending during ink ejection.
When the surface tension is less than 20 mN / m, the wettability of the ink composition on the nozzle surface increases. Therefore, when the ink composition is ejected, the ink composition may adhere asymmetrically around the nozzle holes. is there. In this case, since an attractive force acts between the composition adhering to the nozzle hole and the adhering substance to be ejected, the ink composition is ejected by non-uniform force, and so-called flight bending that cannot reach the target position. Of course, and of course the frequency is high.
On the other hand, if it exceeds 70 mN / m, the shape of the meniscus at the tip of the nozzle is not stable, and it becomes difficult to control the discharge amount and discharge timing of the ink composition.
Accordingly, the viscosity of at least one of the ink composition constituting the solder material, the ink composition constituting the flux material, and the ink composition constituting the conductive material is 5 to 20 mPa · s, and the surface. It is particularly preferable for forming bumps that the tension is 25 to 50 mN / m and the contact angle to the material constituting the nozzle surface of the inkjet head is 30 to 70 °.

The contact angle with respect to the material constituting the nozzle surface for discharging the ink composition provided on the inkjet head is preferably 30 ° to 170 °, and particularly preferably 35 ° to 65 °. When the ink composition has a contact angle in this range, the flight bending of the ink composition can be controlled, and precise patterning becomes possible.
When the contact angle is less than 30 °, the wettability of the ink composition with respect to the material constituting the nozzle surface increases, and thus flight bending occurs as in the case of surface tension. Also. If the angle exceeds 170 °, the interaction between the ink composition and the nozzle holes becomes minimal, and the shape of the meniscus at the tip of the nozzle is not stable, making it difficult to control the ejection amount and ejection timing of the ink composition.
Here, the flight curve means that when the ink composition is ejected from the nozzle, the dot landing position causes a deviation of 50 μm or more from the target position. This occurs mainly due to non-uniform wettability of the nozzle holes or clogging due to adhesion of solid components of the ink composition.

The solid content concentration of the ink composition is preferably 0.01 to 10.0 wt%, more preferably 0.1 to 5.0 wt%, based on the entire composition. If the solid content concentration is too low, the number of ejections increases to obtain the required film thickness, and the mass production efficiency deteriorates. On the other hand, if it is too high, the viscosity becomes high and the dischargeability is affected.
The solid component is preferably dissolved or dispersed in at least one solvent having a vapor pressure at room temperature of 0.005 to 50 mmHg. By using a solvent that does not easily thirst, it is possible to prevent the ink composition from being dried at the nozzle holes, thereby causing thickening, aggregation, and solid adhesion. However, a solvent having a vapor pressure lower than 0.005 mmHg is not suitable because it is difficult to remove the solvent during the film formation process.

Examples of such a solvent include 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, γ-butyrolactone, Aprotic cyclic polar solvents such as N-methyl-2-pyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI) and derivatives thereof, or carbitol acetate (CA), butyl carbitol acetate ( Glycol ether acetic acid such as BCA). Solvents such as CA and BCA are also effective in improving the film formability.
On the other hand, lower alcohols such as methanol (MeOH), ethanol (EtOH), and propyl alcohol are effective in adjusting the surface tension and viscosity, but are desirably 20 wt% or less because of high volatility.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited by these descriptions.
Examples 1-5 show the preparation methods of a solder alloy material ink composition.
As shown below, a metal nanoparticle paste stably dispersed with a particle size of several nm was used as the ink composition.
In this example, the following solder fine particles were used.
(1) Average particle diameter of 6 nm (manufactured by Tartin Co., Ltd.)
(2) Average particle size 5 nm (Senju Metal Industry Co., Ltd.)
(3) Average particle diameter of 8 nm (manufactured by Nippon Alpha Metals Co., Ltd.)
(4) Average particle size of 5 nm (manufactured by Nihon Solder Co., Ltd.)

Example 1
The following materials constituting the solder alloy material ink composition were prepared in advance at a predetermined ratio.
Solder fine particles: Solder fine particles having an average particle diameter of 6 nm (made by Tartin Co., Ltd.) 5 wt%
Dispersant: Styrene acrylic resin 5wt%
Activator: (II-2) 2 wt%
Wetting agent: Glycerol 18%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Solvent: 24% by weight of 1,4-butanediol
First, 5 g of the above solder fine particles (manufactured by Tartin Co., Ltd.) are put into a hot-water jacket and a stainless pressure vessel (with an internal volume of 100 ml) equipped with a stirrer inside, and then carbon dioxide gas is introduced at high pressure. The pressure vessel was heated, and the inside of the vessel was kept in a supercritical state of 50 ± 1 ° C. and 200 ± 5 atm for 5 minutes to dissolve the pigment.
Next, 2 g of a 25% aqueous solution of the above surfactant and 35 ml of 1,3-dimethyl-2-imidazolidinone are introduced into the container, and carbon dioxide is released from the stainless steel pressure-resistant container. Precipitation was performed to prepare dispersion 1.
All the remaining materials constituting the ink composition were added to 42 g of the obtained dispersion, and after stirring well, the mixture was filtered with a 0.5 micron filter to obtain a solder alloy material ink composition 1.
Table 2 shows the dispersion state of each dispersion, the state of the filter, and the properties of each solder alloy material ink composition 1.

(Example 2)
Each of the following materials constituting the solder alloy material ink composition was prepared in a predetermined ratio in advance, and the dispersion 2 and the solder alloy material ink composition 2 were the same as in Example 1 except that these materials were used. Got.
Solder fine particles: Solder fine particles having an average particle diameter of 5 nm (Senju Metal Industry Co., Ltd.) 5 wt%
Dispersant: Styrene acrylic resin 5wt%
Activator: (II-3) 1 wt%
Activator: (III-1) 1.2 wt%
Wetting agent: Glycerol 18wt%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Solvent: 1,4-butanediol 23.8 wt%
Table 2 shows the dispersion state of the dispersion 2, the state of the filter, and the properties of the solder alloy material ink composition 2.

Example 3
The following materials constituting the solder alloy material ink composition were prepared in advance at a predetermined ratio.
Solder fine particles: Solder fine particles with an average particle size of 8 nm (Nippon Alpha Metals Co., Ltd.)
5wt%)
Dispersant: Styrene acrylic resin 5wt%
Activator: 1% by weight of (II-2) surfactant
Activator: activator of _{(VI) (R: C 9} H 19, k: 12) 1 wt%
Wetting agent: Glycerol 18%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Solvent: 24% by weight of 1,4-butanediol
First, after putting the solder fine particles (manufactured by Nippon Alpha Metals Co., Ltd.) into a stainless steel pressure vessel (with an internal volume of 100 ml) equipped with a warm water jacket and a stirrer inside, 92 ml of toluene was introduced at room temperature and normal pressure, Thereafter, the solder fine particles were dissolved by maintaining at 50 ° C. for 5 minutes while maintaining the normal pressure.
Next, the 1,3-dimethyl-2-imidazolidinone was added, and then toluene was volatilized, and solder fine particles were precipitated to prepare dispersion 3.
To 42 g of the obtained dispersion, 2 g of 25% aqueous solution of the above surfactant and all the remaining materials constituting the ink composition were added, stirred well, filtered through a 0.5 micron filter, and solder alloy Material ink composition 3 was obtained.
Table 2 shows the dispersion state of the dispersion 3, the state of the filter, and the properties of the solder alloy material ink composition 3.

(Example 4)
Dispersion 4 and solder alloy material ink composition 4 were prepared in the same manner as in Example 3 except that the following materials constituting the solder alloy material ink composition were prepared in advance at predetermined ratios and these materials were used. Was made.
Solder fine particles: Solder fine particles having an average particle diameter of 5 nm (manufactured by Nihon Solder Co., Ltd.)
5 wt%
Dispersant: Styrene acrylic resin 5wt%
Activator: 1% by weight of activator of (II-4)
Activator: (V) activator (p, q = 20) 0.8 wt%
Wetting agent: Glycerol 18%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Solvent: 1,4-butanediol 24.2 wt%
Table 2 shows the dispersion state of the dispersion 4, the state of the filter, and the properties of the solder alloy material ink composition 4.

(Example 5)
Each of the following materials constituting the solder alloy material ink composition was prepared in advance at a predetermined ratio, and the dispersion 5 and the solder alloy material ink composition 5 were operated in the same manner as in Example 1 except that these materials were used. Was made.
Solder fine particles: 5% by weight of solder fine particles having an average particle diameter of 5 nm (Nihon Solder Co., Ltd.)
Dispersant: Styrene acrylic resin 5wt%
Activator: (I-5) 0.4% by weight
Activator: (IV) Activator (R: C ₁₀ H ₂₁ , K: 7) 1% by weight
Wetting agent: Glycerol 18%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Solvent: 1,4-butanediol 24.6 wt%
Table 2 shows the dispersion state of the dispersion 5, the state of the filter, and the properties of the solder alloy material ink composition 5.

(Evaluation of physical properties of solder alloy material ink composition)
Table 3 shows the results of evaluating the viscosity, surface tension, contact angle with respect to the material constituting the ink ejection nozzle surface of the inkjet head, ejection properties, patterning properties, and film forming properties of these ink compositions. The physical properties and ejection characteristics of the ink composition were evaluated by the following methods.
1) Viscosity: A value at 20 ° C. was measured with an E-type viscometer.
2) Surface tension: The value at 20 ° C. was measured by the plate method.
3) Contact angle: Measured as a static contact angle on the material (Ni-tetrafluoroethylene eutectoid plated water repellent layer) constituting the ink discharge nozzle surface of the inkjet head.
4) Discharge characteristics: An inkjet printer head (Ricoh's IPSIO Jet300) was used. The flying bend was measured by variation in landing of ink droplets on the substrate when the distance between the head and the substrate was 0.6 mm. As the nozzle clogging frequency, the time required for the ink composition to be ejected continuously (frequency: 7200 Hz) until the nozzle hole is clogged due to the solid component of the deposited ink composition, and the ejection becomes impossible. Was measured.
5) Patterning property and film forming property: As shown in FIG. 8A, the peripheral end portion of the pad (41) made of aluminum or the like formed on one surface (40A) of the wafer (40) is formed on the passivation film (42). ) To electrically protect one surface (40A) of the wafer (40). Next, the ink composition (4 pl) containing solder fine particles was discharged from the inkjet head (53) of the inkjet apparatus (52) to the pad shown in FIG. 8 (A), and the solvent was removed at room temperature in a vacuum. Thereafter, the film quality (aggregation, flatness, etc.) of the film formed by heat treatment at 100 ° C. for 10 minutes in the atmosphere was observed with a microscope. The pad has a pad diameter of 20 μm.

Examples 6 to 13 show a method for producing a conductive adhesive layer ink composition.
A metal nanoparticle paste stably dispersed with a particle size of several nm as shown below was used as the ink composition.
In this example, the following conductive materials were used.
6) Gold fine particles: Average particle size 6 nm (manufactured by Tamura Kaken Co., Ltd.)
7) Silver fine particles: Average particle diameter of 5 nm (manufactured by Tamura Kaken Co., Ltd.)
8) Copper fine particles: Average particle diameter of 8 nm (manufactured by Tamura Kaken Co., Ltd.)
9) In fine particles: Average particle size 5 nm (manufactured by Nippon Alpha Metals Co., Ltd.)
10) Conductive carbon fine particles: Average particle diameter of 5 nm (manufactured by Kao Corporation)
11) Conductive resin: average particle size 7 nm (manufactured by Lion Corporation)
12) Anisotropic conductive resin: Average particle size 8 nm (manufactured by Sony Chemical Corporation)

(Example 6)
The following materials constituting the ink composition for forming a conductive adhesive layer were prepared in advance at a predetermined ratio.
Conductive material: Gold fine particles having an average particle diameter of 6 nm (Tamura Chemical Research Co., Ltd.) 5 wt%
Dispersant: Styrene acrylic resin 5wt%
Activator: (II-2) 2 wt%
Wetting agent: Glycerol 18%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Solvent: 24% by weight of 1,4-butanediol

First, after putting 5 g of the gold fine particles in solid content conversion into a stainless pressure vessel (internal volume 5 L) equipped with a warm water jacket and a stirrer inside, carbon dioxide gas is introduced at high pressure and the pressure vessel is heated. The inside of the container was kept in a supercritical state of 50 ± 1 ° C. and 200 ± 5 atm for 5 minutes to dissolve the conductive material.
Next, 2 g of a 25% aqueous solution of the surfactant and 35 ml of 1,3-dimethyl-2-imidazolidinone are introduced into the container, carbon dioxide is released from the stainless pressure vessel, and the conductive material is obtained. A dispersion 6 was prepared by precipitation.
All the other materials constituting the ink composition were added to 42 g of the obtained dispersion, and after stirring well, the mixture was filtered with a 0.5 micron filter to obtain an ink composition 6 for forming a conductive adhesive layer. It was.
Table 4 shows the dispersion state of the dispersion, the state of the filter, and the properties of the conductive adhesive layer forming ink composition.

(Example 7)
The dispersion 7 and the conductive adhesive layer were prepared in the same manner as in Example 6 except that the following materials constituting the ink composition for forming the conductive adhesive layer were prepared in advance at predetermined ratios and these materials were used. A forming ink composition 7 was obtained.
Conductive material: Silver fine particles having an average particle size of 5 nm (Tamura Chemical Research Ltd.) 5 wt%
Dispersant: Styrene acrylic resin 5wt%
Activator: (II-3) 1 wt%
Activator: (III-1) 1.2 wt%
Wetting agent: Glycerol 18wt%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Solvent: 1,4-butanediol 23.8 wt%
Table 4 shows the dispersion state of the dispersion 7, the state of the filter, and the properties of the ink composition 7.

(Example 8)
The dispersion 8 and the conductive adhesive layer were prepared in the same manner as in Example 6 except that the following materials constituting the ink composition for forming the conductive adhesive layer were prepared in advance at predetermined ratios and these materials were used. A forming ink composition 8 was obtained.
Conductive material: copper fine particles having an average particle diameter of 8 nm (Tamura Kaken Co., Ltd.) 5 wt%
Dispersant: Styrene acrylic resin 5wt%
Activator: (II-2) 1% by weight
Activator: (VI) (R: C ₉ H ₁₉ , k: 12) 1% by weight
Wetting agent: Glycerol 18%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Total: 1,4-butanediol 24 wt%
Table 4 shows the dispersion state of the dispersion 8, the state of the filter, and the properties of the ink composition 8.

Example 9
The dispersion 9 and the conductive adhesive layer were prepared in the same manner as in Example 6 except that the following materials constituting the ink composition for forming the conductive adhesive layer were prepared in advance at predetermined ratios and these materials were used. A forming ink composition 9 was obtained.
Conductive material: In fine particles having an average particle diameter of 5 nm (manufactured by Nippon Alpha Metals Co., Ltd.) 5 wt%
Dispersant: Styrene acrylic resin 5wt%
Activator: (II-4) 1% by weight
Activator: (V) (p, q = 20) 0.8 wt%
Wetting agent: Glycerol 18%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Total: 1,4-butanediol 24.2 wt%
Table 4 shows the dispersion state of the dispersion 9, the state of the filter, and the properties of the ink composition 9.

(Example 10)
The following materials constituting the ink composition for forming a conductive adhesive layer were prepared in advance at a predetermined ratio.
Conductive material: Conductive carbon fine particles with an average particle size (made by Kao Corporation) 5 wt%
Dispersant: Styrene acrylic resin 5wt%
Activator: (I-5) 0.4% by weight
Activator: (IV) (R: C ₁₀ H ₂₁ , k: 7) 1% by weight
Wetting agent: Glycerol 18%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Solvent: 1,4-butanediol 24.6 wt%
First, conductive carbon fine particles (made by Kao Corporation) having an average particle diameter of 5 nm are placed in a stainless steel pressure vessel (with an internal volume of 5 L) equipped with a warm water jacket and a stirring device inside, and then 200 ml of toluene at normal temperature and pressure. After that, the conductive material was dissolved by maintaining at 50 ° C. for 5 minutes while maintaining the normal pressure.
Next, 2 g of a 25% aqueous solution of the above surfactant and 35 g of 1,3-dimethyl-2-imidazolidinone are added to the container, and then toluene is volatilized to deposit a conductive material to prepare a dispersion 10. did.
After adding all the remaining materials constituting the ink composition to 42 g of the obtained dispersion and stirring well, the mixture is filtered with a 0.5 micron filter to form the conductive adhesive layer forming ink composition 10. Obtained.
Table 4 shows the dispersion state of the dispersion 10, the state of the filter, and the properties of the ink composition 10 for forming a conductive adhesive layer.

(Example 11)
Each of the following materials constituting the ink composition for forming a conductive adhesive layer was prepared in advance at a predetermined ratio, and the dispersion 11 and the conductive adhesive layer were prepared in the same manner as in Example 10 except that these materials were used. A forming ink composition 11 was obtained.
Conductive material: 5 wt% of conductive resin (made by Lion Corporation) with an average particle size of 7 nm
Dispersant: Styrene acrylic resin 5wt%
Activator: (II-1) 0.3% by weight
Activator: (IV) (p + q = 15) 0.5% by weight
Activator: Activator of (IV) (p + q = 0) 0.5% by weight
Wetting agent: Glycerol 18%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Total: 1,4-butanediol 24.7 wt%
Table 4 shows the dispersion state of the dispersion 11, the state of the filter, and the properties of the ink composition 11.

Example 12
The dispersion 12 and the conductive adhesive layer were prepared in the same manner as in Example 10 except that the following materials constituting the ink composition for forming the conductive adhesive layer were prepared in advance at a predetermined ratio and these materials were used. A forming ink composition 12 was prepared.
Conductive material: Anisotropic conductive resin with an average particle diameter of 8 nm (manufactured by Sony Chemical Co., Ltd.) 5 wt%
Dispersant: Styrene acrylic resin 5wt%
Activator: (II-4) 0.6% by weight
Activator: (V) (p, q = 20) 0.4 wt%
Wetting agent: Glycerol 18%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Total: 1,4-butanediol 25wt%
Table 4 shows the dispersion state of the dispersion 12, the state of the filter, and the properties of the ink composition 12 for forming the conductive adhesive layer.

(Example 13)
Dispersion 13 and conductive adhesive layer were prepared in the same manner as in Example 10 except that the following materials constituting the ink composition for forming a conductive adhesive layer were prepared in advance at a predetermined ratio and these materials were used. A forming ink composition 13 was prepared.
Conductive material: Anisotropic conductive resin with an average particle diameter of 5 nm (manufactured by Sony Chemical Co., Ltd.) 5 wt%
Dispersant: Styrene acrylic resin 5wt%
Activator: (IV) (p + q = 15) 1% by weight
Activator: (IV) (R: C ₁₀ H ₂₁ , k: 7) 1.5% by weight
Wetting agent: Glycerol 18%
Solvent: 1,3-dimethyl-2-imidazolidinone 35 wt%
Solvent: N-methyl-2-pyrrolidone 11 wt%
Solvent: 1,4-butanediol 23.5 wt%
Table 4 shows the dispersion state of the dispersion 13, the state of the filter, and the properties of the conductive adhesive layer forming ink composition 13.

(Evaluation of physical properties of conductive adhesive layer ink composition)
For these ink compositions, Table 5 shows the results of evaluating the viscosity, surface tension, contact angle with respect to the material constituting the ink ejection nozzle surface of the inkjet head, ejection properties, patterning properties, and film forming properties. The physical properties and ejection characteristics of the ink composition were evaluated by the method shown in the preparation of the solder alloy material ink composition.
As shown in Table 5, the discharge property, the patterning property, and the film forming property were sufficient and reached practical levels.

Examples 14-21 show the preparation methods of a flux material ink composition.
An ink composition having the following composition was prepared.

(Example 14)
◎ Rosin Natural rosin: WW rosin 6 parts by weight Hydrogenated rosin 6 parts by weight ◎ Resin Epoxy resin 3 parts by weight ◎ Activator Organic acid activator 1: Benzoic acid 2 parts by weight Organic acid activator 2: Azeethic acid 1 part by weight Halogen compound-based activator: 3-amino-1-propene hydrochloride 2 parts by weight ◎ Wetting agent Glycerol 10 parts by weight ◎ Solvent 2-ethyl-1,3-hexanediol 2 parts by weight ◎ Solvent 1,4-butanediol 68 parts by weight Part
(Total) 100 parts by weight

(Example 15)
◎ Rosin Natural rosin: WW rosin 6 parts by weight Hydrogenated rosin 6 parts by weight ◎ Resin isoprene rubber 4 parts by weight ◎ Activator Organic acid activator 1: Adipic acid 2 parts by weight Halogen compound activator: n-butylamine hydrochloride 1 Part by weight ◎ Wetting agent Ethylene glycol 45 parts by weight ◎ Solvent 2- (2-n-butoxyethoxy) ethanol 36 parts by weight
(Total) 100 parts by weight

(Example 16)
◎ Rosin Natural rosin: WW rosin 7 parts by weight Hydrogenated rosin 7 parts by weight ◎ Resin Polyester elastomer (Toyobo Co., Ltd.) 4 parts by weight ◎ Active agent Organic acid activator 1: Glutaric acid 2 parts by weight 2 parts by weight of azelaic acid Surfactant: 1 part by weight of quaternary ammonium
(Lion Corporation: Arcard C-50 (trade name))
◎ Wetting agent 44 parts by weight of triethylene glycol ◎ Solvent N-methyl-2-pyrrolidone 33 parts by weight
(Total) 100 parts by weight

(Example 17)
◎ Rosin Natural rosin: WW rosin 8 parts by weight Hydrogenated rosin 7 parts by weight Activator Organic acid activator 1: Adipic acid 3 parts by weight Organic acid activator 2: Benzoic acid 5 parts by weight Wetting agent Glycerol 39 parts by weight ◎ Solvent 1,3-butanediol 38 parts by weight
(Total) 100 parts by weight

(Example 18)
◎ Rosin Natural rosin: WW rosin 10 parts by weight Hydrogenated rosin 8 parts by weight ◎ Resin Acrylic resin 5 parts by weight Surfactant: Structural formula (II) 1 part by weight ◎ Wetting agent Glycerol 10 parts by weight Solvent Diethylene glycol monomethyl ether 60 parts by weight
(Total) 100 parts by weight

Example 19
◎ Rosin Natural rosin: WW rosin 8 parts by weight Hydrogenated rosin 8 parts by weight ◎ Resin Polyimide resin 5 parts by weight ◎ Activator Organic acid activator 1: Palmitic acid 3 parts by weight Organic acid activator 2: Abietic acid Surfactant: structural formula (V) 1 part by weight ◎ wetting agent N-methyl-2-pyrrolidone 53 parts by weight ◎ solvent ethylene glycol monobutyl ether 20 parts by weight
(Total) 100 parts by weight

(Example 20)
◎ Rosin Natural rosin: WW rosin 6 parts by weight Hydrogenated rosin 8 parts by weight ◎ Resin Vinyl chloride resin 5 parts by weight ◎ Activator Organic acid activator 1: Stearic acid 3 parts by weight Organic acid activator 2: Benzoic acid 3 parts by weight Part: Surfactant: Structural formula (III) 2 parts by weight Solvent 2,2,4-trimethyl-1,3-pentanediol 5 parts by weight Solvent 1,3-butanediol 68 parts by weight
(Total) 100 parts by weight

(Example 21)
◎ Rosin Natural rosin: WW rosin 8 parts by weight Hydrogenated rosin 8 parts by weight ◎ Resin Acrylonitrile resin 5 parts by weight ◎ Active agent Organic acid activator 1: Formic acid 3 parts by weight Organic acid activator 2: Azelaic acid 3 parts by weight Interface Activator :: structural formula (IV) 1 part by weight ◎ wetting agent glycerol 7.5 parts by weight ◎ solvent ethylene glycol monoethyl ether 64.5 parts by weight
(Total) 100 parts by weight

(Bump fabrication method of the present invention by ink jet method)
Next, preparation of solder bumps using the solder alloy material ink compositions of Examples 1 to 5, the conductive adhesive layer forming ink compositions of Examples 6 to 13 and the flux material compositions of Examples 14 to 21 A method will be described.

First, as shown in FIG. 3, a passivation (93) is formed on the LSI wafer (91) so as to cover a part of the aluminum pad (92) formed on the LSI wafer (91).
Subsequently, as shown in FIG. 4, an intermediate metal layer (94) is formed on the aluminum pad (92) and the passivation (93).
Next, as shown in FIG. 5, a solder alloy material layer (95) made of tin, lead or the like is formed at a position corresponding to the aluminum pad (92) on the intermediate metal layer (94). A solder bump forming flux layer (96) is formed.
When the LSI wafer (91) thus formed with each layer is heated under predetermined conditions to melt the solder alloy material and the flux, a substantially spherical solder bump (97) as shown in FIG. A connection terminal is formed on the aluminum pad (92) via (94).
As this heating device, for example, a wet-back device NRY-101V6LU (model name) manufactured by Yamato Seisakusho is used.

(1) Temperature profile As shown in FIG. 7, the temperature profile of the wet-back process using the flux according to the embodiment starts the wet-back process from the section T1 kept at room temperature, and then keeps up to about 100 ° C. Preheating is performed stepwise by the section T2, the section T3 maintained up to about 200 ° C., and the section T4 maintained up to about 300 ° C.
Subsequently, in this wet-back process, after passing through the main heat of the section T5 maintained at about 350 to 400 ° C., the section T6 maintained at about 200 ° C., the section T7 maintained at about 100 ° C. and the room temperature are maintained. The section is cooled stepwise by the section T8, and the wet-back process is terminated.

(2) Temperature conditions for wetback processing When a wetback device (NRY-101V6LU manufactured by Daiwa Manufacturing Co., Ltd.) is used for wetback processing, the device is provided with a hot plate in the lower stage of the path through which the wafer passes and is heated directly in contact with the wafer. This is a non-contact heating method using an infrared heater from above, and is performed using one or both of the two heating means.
As shown in Table 6, each section in the apparatus was set to two types of temperatures using a hot plate or an infrared (IR) heater.
First, in the wetback apparatus using a hot plate, the first section is set to about 100 ° C. as the preheat, the second section is set to about 200 ° C., the third section is set to about 300 ° C., and the fourth section is set as the main heat. Was set to about 360 ° C., and the fifth section was set to about 200 ° C. and the sixth section was set to about 100 ° C. for cooling of the formed solder bumps.
On the other hand, in the wetback apparatus using the infrared heater, the wet bag process is started from the second section, and the second section is set to about 250 ° C. and the third section is set to about 350 ° C. as preheating. As a main heat, the fourth section was set to about 400 ° C., and the fifth section was set to about 300 ° C. for cooling the solder bumps.
In the wetback apparatus, each section is set to an atmosphere having a nitrogen concentration of about 50 ppm, and the semiconductor chip to be wetback processed is moved in each section at intervals of about 60 seconds to perform the wetback processing. Table 6 shows the temperature conditions of the wet back treatment according to the example.

<Creation of first to eighth bumps>
The solder alloy material ink compositions (4 pl) of Examples 1 to 5 were discharged onto an intermediate metal layer (BLM: Ball Limiting Metal) formed on a pad having a pad diameter of 20 μm and opened at room temperature and vacuum. After removing the solvent therein, heat treatment was performed in the atmosphere at 100 ° C. for 10 minutes to form a solder layer.
Thereafter, the flux ink compositions (4 pl) of Examples 13 to 20 were discharged onto the formed solder layer and heated and melted under the heating and melting conditions shown in Table 6 to form solder bumps with a bump diameter of 20 μm.
Table 7 shows eight examples (first to eighth bumps) in which solder bumps are thus formed on the intermediate metal layer.

<Creation of 9th to 16th bumps>
Next, after the intermediate metal layer (94) in FIG. 5 was formed using the above-described ink composition for forming a conductive adhesive layer, bumps were prepared.
The ink composition for forming a conductive adhesive layer (4 pl) of Examples 6 to 11 was ejected onto a pad having a pad diameter of 20 μm and the solvent was removed at room temperature in a vacuum. A conductive adhesive layer was formed by heat treatment for 10 minutes.
Then, after forming a solder layer using the solder alloy material ink composition as described above, the flux ink composition was discharged and heated and melted in the same manner as described above to form solder bumps with a bump diameter of 20 μm. .
The bumps thus formed are referred to as first to sixteenth bumps (# 1 to # 16). A schematic view of the produced bumps as seen from above is shown in FIG.
Table 8 shows eight examples (9th to 16th bumps) in which solder bumps are formed on the conductive adhesive layer in this way.

<Creation of 17th to 20th bumps (bump diameter: 0.5 μm to 5 μm)>
First, the ink composition for forming a conductive adhesive layer produced in Example 6 was changed to 5 μm, 3 μm by changing the driving voltage, frequency, and pulse width of the head (53) (Ricoh's IPSIO Jet300) of the inkjet printing apparatus (52). On a pad having an opening diameter of 1 μm and 0.5 μm, 1 pl, 0.6 pl, 0.2 pl, and 0.1 pl were discharged and laminated, respectively, and patterning was applied.
After coating, the solvent was removed in vacuum (1 torr) at room temperature for 20 minutes, and then a conductive adhesive layer was formed by heat treatment in a nitrogen atmosphere at 150 ° C. (on a hot plate) for 2 hours.

Next, the solder layer forming ink composition prepared in Example 1 was discharged and laminated to the conductive adhesive layer corresponding to the pad opening diameter of 1 pl, 0.6 pl, 0.2 pl, and 0.1 pl, respectively. .
After the application, the solvent was removed in vacuum (1 torr) at room temperature for 20 minutes, and then a solder alloy material layer was formed by heat treatment in a nitrogen atmosphere at 150 ° C. (on a hot plate) for 30 minutes.

Further, the flux ink composition produced in Example 14 was 1 pl, 0.6 pl, and 0.2 pl on the solder alloy material layer formed on the 5 μm, 3 μm, 1 μm, and 0.5 μm diameter pads, respectively. Then, 0.1 pl was discharged and laminated, and then heat melting was performed under the heat melting conditions shown in Table 6 to form solder bumps.
The diameters of the four types of solder bumps thus formed were 5 μm, 3 μm, 1 μm, and 0.5 μm, respectively.
These four types of solder bumps are referred to as 17th to 20th bumps (# 17 to # 20).

As described above, according to the ink jet method, fine patterning can be performed easily and in a short time, and a solder bump having a very small diameter, which has been difficult in the conventional method, can be formed.
Further, the film thickness can be changed by changing the solid content concentration and the discharge amount of the solder alloy material ink composition.

Unlike the 17th to 20th bump manufacturing examples, as in the 1st to 8th bump manufacturing examples, the ink jet method is used to form the solder layer and the flux layer, but the intermediate metal layer is conventionally formed. A method can also be adopted.
In this way, bumps can be formed by combining a composition that is not very suitable for the ink jet method and an ink composition that is suitable for the ink jet method, so that the degree of freedom in semiconductor design is also one of the advantages. One.
Examples of conventional methods other than the inkjet method include printing methods, transfer methods, dipping methods, spin coating methods, casting methods, capillary methods, roll coating methods, and bar coating methods.

(Preparation of solder bump by conventional method)
Next, a method of forming solder bumps by a conventional method will be described.
Conventional bumps according to the conventional method are formed on the pad (41) on one surface (40A) of the wafer (40) by the following procedure shown in FIGS.
That is, first, as shown in FIG. 8A, the peripheral end portion of a pad (41) made of aluminum or the like formed on one surface (40A) of the wafer (40) is covered with a passivation film (42). One surface (40A) of the wafer (40) is electrically protected.

Next, as shown in FIG. 8B, a metal mask (not shown) having an opening corresponding to each pad (41) on one surface (40A) of the wafer is exposed to each pad (41). As described above, the wafer (40) is placed on one surface (40A) (or a photoresist film is formed so that each pad (41) is exposed).
Subsequently, the wafer (40) is loaded into a sputtering apparatus, and an adhesive layer (44) made of chromium or the like and a barrier metal layer (45) made of copper or the like are sequentially stacked on the pad (41) by sputtering. To do. The BLM film layer (46) composed of the adhesive layer (44) and the barrier metal layer (45) formed in this way has a function of improving the adhesion to the bumps to be formed later.
Thereafter, the above-described metal mask (or the photoresist film is peeled off) placed on one surface (40A) of the wafer (40), and the BLM laminated on the metal mask (or photoresist film). The membrane layer (46) is removed together.
Thus, the BLM film layer (16) is laminated on each pad (41) on one surface (40A) of the wafer (40).

Next, as shown in FIG. 8C, a photoresist film (47) is formed on one surface (40A) of the wafer (40), and the photoresist film (47) is formed according to each BLM film layer (46). After the exposure, development is performed to expose each BLM film layer (46). Thereafter, as shown in FIG. 8D, a bump material (48) made of lead and tin is laminated on one surface (40A) of the wafer (40) by a plating method and a vapor deposition method, respectively.
Next, the photoresist film (47) laminated on one surface (40A) of the wafer (40) is peeled off, and the bump material (48) laminated on the photoresist film (47) is removed. Thus, the bump material (48) is laminated on each BLM film layer (46).
In the conventional example, as a wafer (40) in which a bump material (48) is formed by lamination on each BLM film layer (46), for example, a product manufactured by Tanaka Kikinzoku Co., Ltd. An experiment was performed using, for example, a product manufactured by Japan IBM Corporation as a wafer (40) in which a bump material (48) was formed by vapor deposition on the BLM film layer (46).

Subsequently, as shown in FIG. 8E, on one surface (40A) of the wafer (40) on which the bump material (48) is formed on each BLM film layer (46) by the plating method and the evaporation method. As a flux (not shown), for example, Delta Lux 530 (product name) manufactured by Senju Metal Industry Co., Ltd. is applied. In addition, this flux is apply | coated so that it may become about 5.0-6.0g with respect to one 6-inch wafer.
Then, nitrogen as _{(N 2)} solder heating and melting device (not shown), for example using Daiwa Seisakusho _{N 2 Solder Reflow System NRY-101V6LV} ( product name), internal the _{N 2} solder heating and melting device In a nitrogen atmosphere having an oxygen (O ₂ ) concentration of about 25 to 30 ppm, the bump material (48) formed on each BLM film layer (46) of the wafer (40) is heated and melted.
In this manner, the bump material (48) is melted to synthesize lead and tin to form a conventional bump (48A) having a spherical shape.
These manufacturing processes are simply shown in FIGS.

In addition, as shown in the temperature profile of Table 6 and FIG. 7, this N ₂ solder heating and melting apparatus has six zones with different set temperatures from the first zone to the sixth zone inside each of these zones. Each is set to a predetermined temperature by a hot plate or an infrared (IR) heater.
In this N ₂ solder heating and melting apparatus, the wafer (40) is stopped for a predetermined time in each of the first to sixth zones, and the wafer (40) is heated at each set temperature.
Here, when the temperature is first set using a hot plate in the N ₂ solder heating and melting apparatus, the first zone is set to about 100 ° C., the second zone is set to about 150 ° C., and the subsequent third zone is set to The bump material (48) formed on the pad (41) of the wafer (40) is set to about 250 ° C. and heated stepwise.
The fourth zone is set to about 350 ° C., and the bump material (48) on the BLM film layer (46) of the wafer (40) is heated and melted in the fourth zone.
Further, the fifth zone is set to about 200 ° C., and the sixth zone is set to about 100 ° C., and the bump material (48) heated and melted on the BLM film layer (46) of the wafer (40) is stepped. Then, a conventional bump (48A) is formed on each pad (41) of the wafer (40) via a BLM film layer (46).

On the other hand, when the temperature is set using an infrared heater in this N ₂ solder heating and melting apparatus, the first zone is set to about 150 ° C., the second zone is set to about 250 ° C., and the subsequent third zone is set to 350 ° C. The bump material (48) formed on the BLM film layer (46) of the wafer (40) is heated stepwise by setting the temperature to about 0 ° C.
Further, the fourth zone is set to about 400 ° C., and the bump material (48) on the BLM film layer (46) of the wafer (40) is heated and melted in the fourth zone.
Further, the fifth zone is set to about 350 ° C., and the sixth zone is set to about 250 ° C., and the bump material (48) heated and melted on the BLM film layer (46) of the wafer (40) is stepwise. The conventional bump (48A) is formed on each pad (41) of the wafer (40) through the BLM film layer (46).
In this N ₂ solder heating and melting apparatus, the stop time of the wafer (40) for each of the first to sixth zones is about 30 seconds in the first zone, about 40 seconds in the second zone, and the third zone that follows. Then, it is about 50 seconds. In the fourth and fifth zones, the time is about 40 seconds, and in the subsequent sixth zone, the time is about 60 seconds.

Further, as a method for forming the conventional bump (48A), a solder dipping method was used in addition to the plating method and the vapor deposition method.
In the case of this solder dipping method, a solder resist film (47) is formed on the passivation film (42) on one surface (40A) of the wafer (40) in which the BLM film layer (46) is laminated on the pad (41). Laminate.
Thereafter, for example, Delta Lux 530 (product name) manufactured by Senju Metal Industry Co., Ltd. is applied as a flux to one surface (40A) of the wafer (40).

Next, when the total weight of lead and tin of the bump material (48) is 100%, the weight of lead is preselected so as to be an arbitrary ratio of 90 to 98%, and the weight of tin is set to the weight of lead. The lead and tin (bump material (48)) are melted at a temperature of about 380 ° C. and placed in a dip tank.
Next, the wafer (40) is immersed in the molten lead and tin in the dip tank, and the molten lead is formed on the BLM film layer (46) formed on each pad (41) of the wafer (40). And forming tin.
In this way, the conventional bumps (48A) are formed on the respective BLM film layers (46) in a spherical shape by the surface tension of the molten lead and tin and the action of the flux.

In this way, the glycol (40) having the conventional bumps (48A) formed by the plating method, the vapor deposition method and the solder dipping method is first brought to a temperature of about 50 ° C., for example, Asahi Kasei. It was immersed in Elise M9000 (product name) manufactured by Kogyo Co., Ltd., and washed by shaking for about 20 minutes.
Next, the wafer (40) was immersed in 2-propanol (isopropanol) manufactured by Kanto Chemical Co., Ltd. as a cleaning agent having a temperature about the same as room temperature, and washed by shaking for about 10 minutes. In this way, the flux remaining on the passivation film (42) of the wafer (40) was cleaned.
Thus, a conventional bump (48A) was completed on each pad (41) of the wafer (40).
The solder bumps formed by the plating method, the vapor deposition method and the solder dipping method will be referred to as a first conventional bump, a second conventional bump and a third conventional bump, respectively.

(Characteristics of Example and Conventional Solder Bump)
Solder bumps (first to sixteenth bumps) of the present invention formed by an inkjet method and solder bumps formed by a conventional method (first conventional bump, second conventional bump, third conventional bump) Are compared by a reliability test when an IC chip that is actually cut and separated from the wafer (40) is mounted on a wiring board. did.

First, about the external appearance of the solder bump, the external appearance of the bump expanded 40 times was visually observed using OPTIPHOT XUW-M (product name) manufactured by Nikon Corporation as a metal microscope.
Moreover, about the cross section of a solder bump, the electron microscope (Hereafter, this is called SEM) is used. The appearance and the cross section of the bump were observed.
The results are shown in Table 9.

For the mechanical strength test of the solder bump, a PULL TESTER TYPE PTR-01 (product name) manufactured by Reska Co., Ltd. was used as a strength tester, and Y distance 0.2 mm, Speed 0.1-1.0 mm / s. , 0.1, Location μ, and 5, a shear test and a tensile strength test were performed on the bumps.
First, in the shear test, a force was applied to a predetermined position of the bump from a direction orthogonal to the thickness direction of the wafer (40), and the strength when the bump was torn off was measured.
In the tensile strength test, the bump is pulled away from the one surface (40A) of the wafer (40), and the bump is the pad (41) (in the case of the first to sixteenth bumps) or the BLM film layer (46). The strength at the time of peeling from the conventional bump (48A) was measured.
The results are shown in Table 9.

The detergency test was performed only on the conventional bump (48A) formed by the conventional method in which flux is used at the time of bump formation.
That is, in the cleaning test, after the flux was cleaned, the presence or absence of flux or the like (hereinafter referred to as a residue) remaining on the passivation film (42) of the wafer (40) was observed.
For observation of the residue, as a metallographic microscope, for example, OPTIPHOT XUW-M (product name) manufactured by Nikon Co., Ltd. was used and magnified 40 times, and as SEM, SCANING MICROSCOPE JSM-5300LU (product manufactured by JEOL Ltd.) Name) was used to observe 1000 to 3000 times magnification.

For the reliability test, three types of tests were conducted: a thermal shock program test, an ion migration test, and a high temperature holding test.
First, for the thermal shock program test, using the ESPEC THERMAL SHOCK CHAMBER TSB-2 or TSV-40st (product name) manufactured by Tabai Espec Co., Ltd. as the thermal shock test apparatus, the atmospheric temperature inside the apparatus is set to -30. It was changed cyclically in the range of ˜150 ° C., and whether or not cracks were generated at the joint portion between the bump and the pad (41) was confirmed inside the apparatus.
In this thermal shock test apparatus, the inside is kept at a temperature of about −30 ° C. for about 1 hour, and then the temperature is raised to a temperature of about 150 ° C. over a period of about 30 minutes. Is used for about 1 hour, and after that, the temperature change of one cycle is repeated over 3 hours so that the temperature is lowered to about −30 ° C. over about 30 minutes. It is.

  Further, in the ion migration test, an ion migration measurement system SIR10 (product name) manufactured by Enomoto Kasei Co., Ltd. is used as an ion migration tester, and the IC chip is used under a high temperature and high humidity set in advance to a predetermined temperature and humidity. Of the bumps formed on each pad (41), an electric field was applied to adjacent bumps, and the presence or absence of a short circuit between these adjacent bumps caused by metal ions deposited on the cathode side was confirmed.

  Furthermore, in the high temperature holding test, a bump and BLM film layer in an atmosphere held at 120 ° C. and 210 ° C. using a constant temperature and humidity chamber (product name) manufactured by Advantest Co., Ltd. as a high temperature holding tester. The state of deterioration of the BLM film layer (46) due to mutual diffusion with (46) was measured.

The results obtained by the various tests described above will be described.
Table 9 shows the test results of the first to third solder bumps of the present invention formed by the ink jet method and the first to third conventional bumps formed of the conventional method. The same results as those of the first to third solder bumps were obtained for the fourth to sixteenth solder bumps.

As shown in Table 9, first, in the observation with a metal microscope, the surface of the conventional bump is blackened, and a large number of deformed bumps and scattered bumps are generated. (48A) A bridge is also generated by contact of each other.
The conventional bump will be specifically described with reference to FIG. 9A and FIGS. 9B and 9C which are enlarged views of FIG. 9A. Each pad (41) of the wafer (40) is described below. A plurality of scattering bumps (60) are generated in the peripheral portions of the conventional bumps (48A) formed thereon, respectively, and a deformed bump (61) in contact with the scattering bumps (60) is observed. The
On the other hand, in the first to sixteenth bumps of the present invention, the surface is glossy and has an ideal spherical shape, and a good surface property and shape are observed.

On the other hand, in the observation by SEM, when the cross section of each of the first to third conventional bumps is observed, many voids and cracks inside the conventional bump (48A) are confirmed, and many irregular bumps due to these voids and cracks are found. It is confirmed.
Further, the BLM film layer (46) on the pad (41) of the wafer (40) and the conventional bump (48A) are coarsely interdiffused, and the deterioration of the BLM film layer (46) is confirmed.
That is, as shown in FIGS. 11A to 11C, the bump material 48 formed on the BLM film layer 46 on the pad 41 of the wafer 40 (FIG. 11A). When this is heated and melted, the conventional bump (48A) originally becomes spherical (FIG. 11B).
However, if the blending amounts of lead and tin in the bump material (48) vary, the synthesis of the lead and tin becomes non-uniform, resulting in voids (65) and cracks (66) and scattered bumps (60). Will occur.
On the other hand, in the first to sixteenth bumps of the present invention, voids (65) and cracks (66) are not generated inside, and are firmly fixed on the pads (41) of the wafer (40).

Next, the strength test results will be described.
First, in the shear test, the first to third conventional bumps are broken by a force of about 5 kg. On the other hand, in the first to sixteenth bumps of the present invention, no breaking occurs with a force of about 5 kg, and for the first time with a force of about 10 kg.
On the other hand, in the tensile test, the first to third conventional bumps peel from the BLM film layer (46) with a force of about 500 kg, whereas the first to sixteenth bumps of the present invention have a force of about 1600 kg. It will be peeled off from the pad (41) for the first time.

In the shear test, when the force when the bump is torn off is 8 kg or more, it is within the standard, and when the force is less than this (less than 8 kg), it is determined that the standard is out of standard.
Also, in the tensile test, when the force when the bump is peeled off from the BLM film layer (46) or the pad (41) is 1200 kg or more in advance, it is within the standard, and when the force is less than this (less than 1200 kg), it is out of standard. It is stipulated.
Therefore, the first to third conventional bumps are both out of the standard in the shear test and the tensile test, and the first to sixteenth bumps of the present invention are both in the standard in the shear test and the tensile test.
In addition, the tensile test and shear test performed on the 17th to 20th bumps of the present invention were performed by setting the standard at 20 μm diameter as 8 kg shear and 1200 kg tensile. The results are shown in Table 10. It is as follows.

また、第１７〜第２０のバンプのシエアー強度と引っ張り強度以外の試験結果については、第１〜第１６のバンプの結果と同様に良好であった。

Further, the test results other than the shear strength and tensile strength of the 17th to 20th bumps were as good as the results of the 1st to 16th bumps.

In the detergency test, a flux residue (hereinafter referred to as a black residue) that is burnt black by heating and melting is observed around the first to third conventional bumps, and the bump material. A white residue composed of organic lead and organic tin, which is considered to be generated by a chemical reaction between lead and tin of (48) and an organic acid compound contained in the flux, is observed.
That is, as shown in FIGS. 12, 13, and 15, a large number of black residues (80) are generated around the first to third conventional bumps (FIG. 12) and the wafer (40). A large number of white residues (81) are generated on the passivation film (42) (FIG. 13), and these black residues (80) and white residues (81) are not cleaned in the cleaning of the wafer (40). It remains without being removed.

In the thermal shock program test, which is one of the reliability tests, in the case of the first to third conventional bumps, the first to third conventional bumps and the BLM film layer (46) in 500 cycles from the start of the test. ) Cracks occur at the joints.
On the other hand, in the case of the first to sixteenth bumps of the present invention, even if 1000 cycles of a predetermined standard have passed since the start of the test, there is no contact between the bump and the intermediate metal layer or the conductive adhesive layer. Cracks do not occur, and the bump and the intermediate metal layer or the conductive adhesive layer are fixed.

In the ion migration test which is one of the reliability tests, in the case of the first to third conventional bumps, adjacent bumps are short-circuited after about 500 hours have elapsed from the start of the test.
On the other hand, in the case of the first to sixteenth bumps of the present invention, adjacent bumps are not short-circuited even after elapse of 1000 hours of a predetermined standard from the start of the test, and each pad ( 41) The original state formed above is maintained.

Further, in the high temperature holding test which is one of the reliability tests, in the case of the first to third conventional bumps, first, after about 500 hours have elapsed from the start of the test at a temperature of about 120 ° C., these first to first bumps are used. No. 3 conventional bump and the BLM film layer (46) are interdiffused to deteriorate the BLM film layer (46).
For this reason, it becomes difficult for the BLM film layer (46) to maintain a predetermined strength for fixing the first to third conventional bumps and the pads (41) of the wafer (40). On the other hand, after about 100 hours have passed from the start of the test at a temperature of about 210 ° C., the first to third conventional bumps and the BLM film layer (46) mutually diffuse as described above.
Accordingly, in this case as well, it is difficult for the BLM film layer (46) to maintain a predetermined strength for fixing the first to third conventional bumps and the pads (41) of the wafer (40).
On the other hand, in the case of the first to sixteenth bumps of the present invention, these first to sixteenth to sixteenth even after elapse of 1000 hours of a predetermined standard from the start of the test at each temperature of 120 ° C and 210 ° C. The bump and the BLM film layer do not mutually diffuse, and the bump is fixed on each pad (41) of the wafer (40).

  The conventional results of the bump forming method according to the present invention and the conventional bump forming method are shown in Table 11 and will be described in detail later.

First, with regard to the waste liquid treatment in the bump formation process, the conventional bump formation method requires waste liquid treatment for the bump material formation process, and after the bump material is heated and melted, a large amount of waste liquid is also produced in the flux cleaning process. As a result, waste liquid treatment becomes important.
On the other hand, in the bump forming method of the present invention, the amount of flux used is very small, that is, the amount ejected by the ink jet method, so that waste liquid treatment equipment for treating waste liquid such as organic solvents used in the cleaning process is easy. The bump forming process can be simplified.

As for the bump forming process, the conventional method requires a BLM film layer forming process and a bump material forming process, and the BLM film layer forming process and the bump material forming process respectively include a photoresist film (47) forming process. And a step of removing the photoresist film (47) is necessary. Therefore, the bump formation process is complicated and requires a lot of work time.
In contrast, the bump forming method of the present invention does not require the above-described steps as in the conventional method, and the bump forming step is simple.

Furthermore, when the uniformity of the bumps formed on each pad of the wafer is conventional, there is a variation in the amount of lead and tin in the bump material (48) formed on the BLM film layer (46) in the conventional method. There is.
For this reason, the conventional bumps (48A) formed on the pads (41) of the wafer (40) vary in height and shape.
On the other hand, in the present invention, ink of a uniformly controllable discharge amount is applied by the ink jet method, so that the shape and size of the bumps to be formed are accurate, and each is formed on each pad of the wafer. The formed bump has a substantially uniform height and shape.

Further, when the yield of the bumps formed on each pad (41) of the wafer (40) is conventionally, in the conventional method, the height and shape of the conventional bump (48A) are varied, and the conventional method is used. Voids and cracks are generated inside the bump (48A). For this reason, even if the conventional yield is good, the yield is about 90%.
On the other hand, in the bump forming method of the present invention, a uniform discharge amount of ink is applied by an ink jet method, and an accurate size bump is formed, so that the yield can be almost 100%.

Also, comparing the economics of bump formation, in the conventional method, in the BLM film layer forming step and the bump material forming step, the photoresist film (47) peeling step is performed on one surface (40A) of the wafer (40). 99% or more of the BLM film layer (46) and the bump material (48) are removed with respect to the entire weight of the laminated BLM film layer (46) and the bump material (48), and the BLM film layer is less than 1%. Only (46) and bump material (48) are used, which increases the cost.
In contrast, in the bump forming method of the present invention, a small amount of ejected ink is applied by the ink jet method, and all of the applied material is used for bump formation, so compared with the bump forming method by the conventional method. Economic efficiency is greatly improved.

Further, when the adhesion between the pad (41) and the bump of the wafer (40) is conventionally known, in the conventional method, the BLM film layer (45) (Cr and Cu) and the conventional bump (48A) are changed depending on the environment such as temperature and humidity. ) (Pb and Sn) mutually diffuse, and the BLM film layer (45) deteriorates in a conventional short time, and in some cases, the conventional bump (48A) may be peeled off from the BLM film layer (45). .
On the other hand, in the bump forming method of the present invention, the conductive adhesive layer and the bumps (Pb and Sn) do not mutually diffuse, but only the deterioration of the conductive adhesive layer itself. The pad (41) and the bump are fixed with good adhesion through the conductive adhesive layer for a particularly long time.
Therefore, in the bump forming method of the present invention, the BLM film layer forming step and the bump material forming step as in the conventional bump forming method are not required, and the bump forming step can be simplified.

Furthermore, in the bump forming method according to the present invention, a uniform discharge amount of ink is applied by an ink jet method to form an accurate size bump, so that the bump height generated in the conventional bump forming method can be reduced. It is possible to prevent a bridge generated due to the occurrence of variations, voids (65) and cracks (66) inside the bumps, bumps having different sizes, irregular-shaped bumps (61), and scattered bumps (60).
That is, bumps having substantially uniform physical properties such as surface properties, shapes and compositions of the bumps can be formed on the pads (41), and the yield of the bumps formed on each pad (41) can be improved. it can.
In addition, the bump forming method according to this embodiment does not require the step of stripping the photoresist film (47) as in the conventional bump forming method, whereby bumps are formed on each pad (41) of the wafer (40). The cost in forming can be reduced, and thus the economy in bump formation can be significantly improved.

Furthermore, in the bump forming process of the present invention, a conductive adhesive layer is formed on each pad (41) of the wafer (40), and bumps are formed thereon, whereby each of these pads ( 41) The adhesion strength of each bump with respect to 41) can be improved step by step.
Furthermore, the conductive adhesive layer and the bumps do not mutually diffuse, and the degree of adhesion of the bumps to the pads (41) described above can be maintained over a conventional long time.

Furthermore, in the bump forming method of the present invention, as compared with the conventional bump forming method, it can be seen from the conventional results of reliability tests such as the above-described thermal shock program test, heat thermal shock test, ion migration test and high temperature holding test. In addition, the reliability of each bump formed on each pad (41) of the wafer (40) can be significantly improved.
Further, in a semiconductor device in which bumps are formed on the pads (41) by the bump forming method of the present invention, the pads (41) and the corresponding bumps are connected by a conductive adhesive layer. As a result, the pads (41) and the corresponding bumps can be easily fixed as a result.
In addition, the adhesion strength of each bump to each pad (41) can be maintained for a conventional long time.

Further, as described above, each pad (41) and the corresponding bump are fixed by the conductive adhesive layer, so that each pad (41) and the corresponding bump can be easily fixed. Thus, it is possible to realize a semiconductor device that can significantly reduce the work time in the bump formation process.
In the above-described embodiment, the case where the wafer (40) on which a plurality of IC circuits corresponding to the IC chip are formed is used as the bump formation target is described. However, the present invention is not limited to this, and the LSI is not limited thereto. (Large Scale IC) Various other bump forming objects such as a wafer on which a plurality of circuits corresponding to a chip are formed, a ball grid array (BGA) and a chip size package (CSP) are used. You may do it.

  In the above-described embodiments, the case where the conductive adhesive layer is formed by the ink jet method has been described. However, the present invention is not limited to this, and the wafer (40) is previously formed by a method such as a metal mask printing method or a screen printing method. A conductive adhesive layer (46) may be formed on each pad (41), and a bump may be formed on each of the conductive adhesive layers by an ink jet method.

(Effect of the flux ink composition according to the present invention)
According to the flux ink compositions 14 to 21 having the above composition, in the solder bump formation by the ink jet system, ink jet suitability is achieved by an ink formulation containing rosin, activator, solvent, polyol, glycol ether, surfactant and wetting agent. It was confirmed that the material could be discharged without any problem and could be patterned on the wafer.
In addition, according to the method of the present invention, bumps having a minute diameter, which was considered impossible by the conventional method, can be produced. Of course, those having a diameter of 30 μm or less have a diameter of 10 μm or less, further 1 μm or less. It was confirmed that the bumps having the above can be produced.

Also in the characteristics of solder bumps, it is confirmed that lead bumps and tin can be uniformly melted to form smooth and glossy solder bumps Nos. 1 to 20, and that there are no irregular shaped solder bumps due to chipping or scattered solder bumps. did it.
Thus, by using each of the flux ink compositions 14 to 21, it was confirmed that the solder bumps 1 to 11 had a spherical shape close to an ideal shape.
Moreover, in each flux ink composition 14-21, since lead and tin are fuse | melted uniformly and the solder bumps 1-11 without a void and a crack can be formed inside, between the said solder bumps 1-11 and an intermediate metal layer It was confirmed that the adhesiveness could be improved. Thereby, it has confirmed that the solder bump 1st-20th shear strength and tensile strength could be improved.

As an activator to be contained in the flux ink composition, (1) surface such as decomposition and sublimation in the temperature range of 100 ° C. to 300 ° C. to remove the oxide film on the surface of the solder alloy material, improvement of solderability and imparting surface gloss An organic acid activator that exhibits the effect of improving the properties and does not produce a residue, and (2) it decomposes and activates in the temperature range of 350 ° C to 400 ° C to remove voids inside the bumps and prevent solder alloy scattering. In the solid content of the flux ink composition for forming solder bumps, 0.01 is used in combination with a halogen compound activator that exhibits an effect of uniformly melting the solder alloy materials and generates a residue. When the solder bumps are formed as in # 1 to # 20 when 100% by weight and 10% by weight of (2) are contained in a ratio of 0.01% to 10% by weight, respectively, ℃ ~ During preheating in the temperature range of 00 ° C., the organic acid activator exerts an effect on the surface properties and shape of the solder bump, and in the main heat in the temperature range of 350 ° C. to 400 ° C., the halogen compound activator becomes the solder bump. It was confirmed that the solder bumps were satisfactorily formed while exhibiting an effect on the formation and sufficiently satisfying the functions expected when forming the solder bumps.
Further, it was confirmed that the adhesive strength between the solder bump and the intermediate metal layer was sufficient, the shear strength was sufficient, the tensile strength after mounting was sufficient, and the characteristics were greatly improved.

  Further, as an activator to be included in the flux ink composition, (3) decomposition and sublimation in the temperature range of 100 ° C. to 300 ° C., removal of the oxide film on the surface of the solder alloy material, improvement of solderability, provision of surface gloss, etc. An organic acid activator that exhibits the effect of improving the surface properties of the solder and (4) oxidation of the surface of the solder alloy material by decomposition activation in the temperature range of 100 ° C. to 300 ° C. and 350 ° C. to 400 ° C. Demonstrates effects of improving surface properties such as film removal, improvement of solderability, surface gloss, etc., removing voids inside bumps, preventing solder alloy scattering, or uniforming of solder alloy materials When used in combination with a surfactant that exhibits the effect of melting, from # 1 to # 20, from preheat in the temperature range of 100 ° C to 300 ° C and 350 ° C to 400 ° C, the main heat Therefore, the above-mentioned organic acid activator and surfactant exert an effect on the surface property and shape of the solder bump, and also have an effect on the formation of the solder bump, and are expected when forming the solder bump. It was confirmed that the solder bumps were satisfactorily formed with satisfactory functions.

From this, also in Example 3, it was confirmed that the adhesive strength between the solder bump and the intermediate metal layer was sufficient, the shear strength was sufficient, the tensile strength after mounting was sufficient, and the characteristics were greatly improved. .
Furthermore, when the flux ink composition for forming solder bumps of Examples 14 to 21 was used, it was confirmed from the above that the productivity was greatly improved.

Further, each of the flux ink compositions 1 to 9 can greatly improve the heat resistance of the rosin to the main heat of the wet-back process by blending the resin. As a result, it was confirmed that the formability of the film formed on the solder bump surface can be improved.
Further, each of the flux ink compositions 1 to 9 can eliminate the burning of the rosin, thereby improving the cleaning properties of the formed solder bumps 1 to 11 and eliminating the residual flux.
Thereby, the solder bumps 1 to 11 formed using the respective flux ink compositions 1 to 9 improve the quality reliability after mounting the semiconductor chip on which the solder bumps 1 to 11 are formed on the wiring board. I was able to confirm it.

Further, each of the flux ink compositions 1 to 9 uses an organic acid compound and a halogen compound or an organic acid compound as an activator and an activator that is activated in both the preheat and main heat stages. Since the activator can be activated over a wide range up to the main heat, it was confirmed that the dispersibility of the activator can be improved and the activation efficiency can be improved.
Further, each of the flux ink compositions 1 to 9 can improve the drying property of the solvent during the wet-back process by having the solvent have a boiling point of about 150 to 300 ° C., preferably about 220 to 250 ° C. I was able to confirm.

  As described above, the rosin in which the resin is mixed in an arbitrary ratio of about 1% to 99% with respect to the total weight of the natural rosin and the hydrogenated rosin, the activator in which the organic acid compound and the halogen compound are mixed, and 150 Realizing a flux ink composition that can be used even under high temperature conditions such as wet-back treatment by blending with a solvent having a boiling point of about ~ 300 ° C, preferably about 220-250 ° C to produce a flux. I was able to.

In the above-described embodiment, the case where the resin is used as a solute to be blended at an arbitrary ratio of 1% to 99% with respect to the total weight of the natural rosin and the hydrogenated rosin has been described. The invention is not limited to this, and various other solutes may be used as long as they are heat-resistant to natural rosin and hydrogenated rosin and can be dissolved in a solvent.
In the above-described embodiments, the case where the flux ink is used to form the solder bumps into a spherical shape by the wet-back process has been described. However, the present invention is not limited to this, and in other high temperature conditions. You may make it apply to the various processes etc. which use a solder.

It is a top perspective view which shows an example of the structure of the printer head for inkjet used for the bump formation method of this invention. It is sectional drawing which shows an example of the structure of the nozzle part of the inkjet printer head used for the bump formation method of this invention. FIG. 3 is a main part enlarged cross-sectional view showing a solder bump forming method in the order of steps and showing a step of forming a passivation on an LSI wafer. It is a principal part expanded sectional view which shows the formation method of a solder bump in order of a process, and shows the process of forming an intermediate metal layer. It is a principal part expanded sectional view which shows the formation method of a solder bump and shows the process of forming the solder alloy material layer and the solder bump formation flux layer. It is a principal part expanded sectional view which shows the formation method of a solder bump in order of a process, and shows the state in which the solder bump was formed. It is a basic diagram which shows the temperature profile of the wet-back process by an Example. It is an approximate line sectional view showing the formation procedure of the conventional bump. It is an approximate line sectional view showing a situation of a conventional bump formed on a pad of a wafer. It is a basic diagram which shows the shape of the bump formed using the flux by an Example. It is a basic diagram which shows the mode of the irregular-shaped bump and scattering bump in a bump for conventional. It is a basic diagram with which it uses for description of the flux residue generated by formation of the bump for conventional. It is a basic diagram with which it uses for description of the white residue which generate | occur | produced on the passivation film by formation of the bump for conventional. It is a figure which shows a solder bump formation means. It is a figure which shows the shape of the solder bump formed using the conventional flux. 1 is a schematic diagram of a supercritical fluid device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor chip 2 Al pad 3 Passivation film 4 Polyimide film 5 Intermediate metal layer 6 Lead layer 7 Tin layer 8 Flux 9 Solder bump 10 Inkjet head 11 Nozzle plate 12 Solder bump 13 Diaphragm 14 Solder bump 15 Partition member 16 Solder bump 18 Solder bump 19 Ink chamber 21 Liquid reservoir 23 Supply port 25 Nozzle hole 26 Ink repellent layer 27 Ink introduction hole 29 Piezoelectric element 31 Electrode 33 Nozzle surface 40 Wafer 40A One surface of wafer 41 Pad 42 Passivation film 44 Adhesive layer 45 Barrier metal layer 46 Intermediate Metal layer 47 Photoresist film 48 Bump material 48A Conventional bump 50 Bulkhead 51 Substrate 52 Inkjet device 53 Inkjet head 54 Ink composition 60 Spatter bump 61 Deformed bump 65 Void 66 Crack 80 Black Residual 81 White residual 91 LSI wafer 92 Aluminum pad 93 Passivation 94 Intermediate metal layer 95 Solder alloy material layer 96 Solder bump forming flux layer 97 Solder bump 101 Tank 102 Pump 103 Container 104 Filter 105 Mixing with solvent 106 Back pressure valve 107 Collection 108 Pressure gauge 109 Preheating part 110 Thermal insulation part

Claims (32)

A semiconductor element in which an intermediate metal layer and a bump are sequentially provided on an external electrode pad, and the diameter of the bump is 30 μm or less. The diameter of the said bump is 0.001-10 micrometers, The semiconductor element of Claim 1 characterized by the above-mentioned. The semiconductor element according to claim 1, wherein the bump diameter is 0.001 to 1 μm. 4. The bump according to claim 1, wherein the bump is formed by heating and melting a solder alloy material layer and a flux material layer formed on the intermediate metal layer by an ink jet method. The semiconductor element as described in. The semiconductor element according to claim 1, wherein the intermediate metal layer is a conductive adhesive layer formed by an inkjet method. A solder alloy material layer and a flux material layer are sequentially formed on an intermediate metal layer formed on an external electrode pad of a semiconductor element, and then the solder alloy material layer and the flux material layer are heated and melted to bump. A method of forming a bump, wherein a solder alloy material layer is formed by an ink jet method. The ink composition used for the ink jet system that constitutes the solder alloy material is prepared by a manufacturing method including a process performed in a supercritical fluid or a subcritical fluid. Bump formation method. 8. The bump forming method according to claim 6, wherein the ink composition constituting the solder alloy material contains at least a solder material, an organic solvent, and a wetting agent. A solder alloy material layer and a flux material layer are sequentially formed on an intermediate metal layer formed on an external electrode pad of a semiconductor element, and then the solder alloy material layer and the flux material layer are heated and melted to bump. A method of forming a bump, wherein the intermediate metal layer is a conductive adhesive layer, and the conductive adhesive layer is formed by an ink jet method. The ink composition used for an ink jet system that constitutes a conductive material is prepared by a production method including a process performed in a supercritical fluid or a subcritical fluid. Bump formation method. The bump forming method according to claim 9 or 10, wherein the ink composition constituting the conductive material contains at least a conductive material, an organic solvent, and a wetting agent. A solder alloy material layer and a flux material layer are sequentially formed on an intermediate metal layer formed on an external electrode pad of a semiconductor element, and then the solder alloy material layer and the flux material layer are heated and melted to bump. A method of forming a bump, wherein a flux material layer is formed by an ink jet method. The bump forming method according to claim 12, wherein the ink composition constituting the flux material and used in the ink jet system contains at least a rosin, an activator, and an organic solvent. A bump forming flux containing at least a rosin, an activator, an organic solvent, a polyol, a glycol ether, a surfactant, and a wetting agent is used as the activator at a temperature of 100 ° C. to 300 ° C. 14. The bump forming method according to claim 12, wherein a component that decomposes and sublimates in a range and a component that decomposes and activates in a temperature range of 350 ° C. to 400 ° C. are included. A natural rosin, a hydrogenated rosin, a solute blended in an arbitrary ratio of 1% to 99% with respect to the total weight of the natural rosin and the hydrogenated rosin, an activator activated at a predetermined temperature, The bump forming method according to claim 13 or 14, comprising a natural rosin, a hydrogenated rosin, the solute, and a solvent for dissolving the activator. The bump forming method according to any one of claims 13 to 15, wherein the solute is formed by mixing a single resin or a plurality of synthetic resins, natural rubber, synthetic rubber, or elastomer. At least one of the ink composition constituting the solder material, the ink composition constituting the flux material, and the ink composition constituting the conductive material has a viscosity of 1 to 20 mPa · s and a surface tension of The bump forming method according to any one of claims 6 to 16, wherein a contact angle with respect to a material constituting a nozzle surface of the ink jet head is 20 to 70 mN / m, and 30 to 170 °. The viscosity of at least one of the ink composition constituting the solder material, the ink composition constituting the flux material, and the ink composition constituting the conductive material is 5 to 20 mPa · s, and the surface tension is The bump forming method according to any one of claims 6 to 17, wherein a contact angle with respect to a material constituting the nozzle surface of the ink jet head is 25 to 50 mN / m, and 30 to 70 °. The solid content concentration of at least one of the ink composition constituting the solder material, the ink composition constituting the flux material, and the ink composition constituting the conductive material is 0.01 to 10.0 wt%. The bump forming method according to claim 6, wherein the bump forming method is a percentage. The vapor pressure of at least one of the ink composition constituting the solder material, the ink composition constituting the flux material, and the ink composition constituting the conductive material is 0.001 to 50 mmHg (room temperature). The bump forming method according to claim 6, comprising at least one kind of solvent. A bump formed by the method according to claim 6. A solder alloy material layer and a flux material layer are sequentially formed on an intermediate metal layer formed on an external electrode pad of a semiconductor element, and then the solder alloy material layer and the flux material layer are heated and melted to bump. Used to form a solder alloy material layer by an ink jet method and formed by a manufacturing method including a process performed in a supercritical fluid or a subcritical fluid. An ink composition constituting a solder alloy material. The ink composition constituting the solder alloy material according to claim 22, comprising at least a solder alloy material, an organic solvent, and a wetting agent. A solder alloy material layer and a flux material layer are sequentially formed on an intermediate metal layer formed on an external electrode pad of a semiconductor element, and then the solder alloy material layer and the flux material layer are heated and melted to bump. Used to form a conductive adhesive layer, which is an intermediate metal layer, by an inkjet method, and is manufactured in a manufacturing process including a process performed in a supercritical fluid or a subcritical fluid. An ink composition constituting a characteristic conductive material. The ink composition constituting the conductive material according to claim 24, comprising at least a conductive material, an organic solvent, and a wetting agent. A solder alloy material layer and a flux material layer are sequentially formed on an intermediate metal layer formed on an external electrode pad of a semiconductor element, and then the solder alloy material layer and the flux material layer are heated and melted to bump. An ink composition constituting a flux material, which is used to form a flux material layer in forming an ink by an ink jet method and contains at least a rosin, an activator, and an organic solvent. A bump forming flux containing at least rosin, an activator, an organic solvent, a polyol, a glycol ether, a surfactant, and a wetting agent. As an activator, a component that decomposes and sublimates in a temperature range of 100 ° C. to 300 ° C. and 350 ° C. to 27. The ink composition constituting the flux material according to claim 26, wherein a component that is decomposed and activated in a temperature range of 400 ° C. is included. A natural rosin, a hydrogenated rosin, a solute blended in an arbitrary ratio of 1% to 99% with respect to the total weight of the natural rosin and the hydrogenated rosin, an activator activated at a predetermined temperature, 28. The ink composition constituting the flux material according to claim 26, wherein the ink composition comprises a natural rosin, the hydrogenated rosin, the solute, and a solvent that dissolves the activator. 29. The ink composition constituting the flux material according to claim 28, wherein the solute is formed by mixing a single or a plurality of synthetic resins, natural rubber, synthetic rubber, or elastomer. At least one of the ink composition constituting the solder material, the ink composition constituting the flux material, and the ink composition constituting the conductive material has a viscosity of 1 to 20 mPa · s and a surface tension of The ink composition according to any one of claims 22 to 29, wherein the ink composition has a contact angle of 20 to 70 mN / m, and a contact angle with respect to a material constituting the nozzle surface of the ink jet head is 30 to 170 °. The solid content concentration of at least one of the ink composition constituting the solder material, the ink composition constituting the flux material, and the ink composition constituting the conductive material is 0.01 to 10.0 wt%. The ink composition according to any one of claims 22 to 30, wherein the ink composition is%. The vapor pressure of at least one of the ink composition constituting the solder material, the ink composition constituting the flux material, and the ink composition constituting the conductive material is 0.001 to 50 mmHg (room temperature). 32. The ink composition according to claim 22, comprising at least one kind of solvent.

Images