JP2003318220A - Method and device for mounting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting method and a mounting device which develop fully high washing effect by adding another factor in washing, even if the strength of energetic wave or energetic particle is lowered for preventing generation of charge-up damage and can thereby carry out alignment and junction at a room temperature or a low temperature close to it, thus realizing both improvement of washing effect and highly precise mounting. <P>SOLUTION: In a mounting method for jointing junction matters mutually after a junction surface of at least one junction matter is washed, the washing is carried out by irradiating the junction surface with energetic wave or energetic particle while heating the junction matter. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting method and a mounting apparatus for bonding objects to be bonded after cleaning the bonding surfaces with energy waves or energy particles, and particularly to charge-up damage to the objects to be bonded during cleaning. The present invention relates to a mounting method and a mounting apparatus capable of improving a cleaning effect while suppressing the temperature, enabling low temperature bonding, and improving mounting accuracy.

[0002]

2. Description of the Related Art There is known a technique in which objects to be bonded are bonded together after cleaning the bonding surfaces with energy waves or energy particles. For example, Japanese Patent No. 2791429 discloses a method of bonding the silicon wafers to each other at room temperature by cleaning the bonding surface of the silicon wafers with an energy wave or energy particles such as an ion beam or an atomic beam in a vacuum at room temperature prior to bonding. It is disclosed. In this method, oxides and organic substances on the bonding surface of the silicon wafer are removed by being blown off by the above-mentioned beam by etching, the surface is formed by the atoms of silicon, and the surfaces are kept at room temperature due to the high bonding force between the atoms. You can join with.

In such a room temperature bonding method, the objects to be bonded can be bonded together at room temperature at the atomic level by removing the layer (so-called contamination layer) made of oxides or organic substances at the bonding interface. For that purpose, how to sufficiently remove the contamination layer is an important point.If the contamination layer is not sufficiently removed, room temperature bonding becomes difficult, and heating to a considerably high temperature is required as in general bonding. It is necessary to perform heat bonding.

In order to sufficiently remove the contamination layer, it is necessary to increase the intensity of energy waves or energetic particles such as ion beams or atomic beams to be irradiated to enhance the cleaning effect. Charge-up is likely to occur in the object to be bonded, and if the object to be bonded is a semiconductor, the circuit may be fatally damaged by the charge-up. Therefore, especially when there is a possibility of such charge-up damage, the cleaning strength has to be reduced, and the cleaning effect is reduced, so the contamination layer is not sufficiently removed, and heating is also used during bonding. Was needed.

The heating at the time of joining causes thermal expansion of the article to be joined and its holding means, which causes errors and distortions in alignment and joining, and causes a side effect of deteriorating mounting accuracy. ing.

[0006]

Therefore, an object of the present invention is to pay attention to the above problems and to reduce the intensity of energy waves or energy particles in order to prevent the occurrence of charge-up damage. By adding another element at the time of cleaning, a sufficiently high cleaning effect can be expressed, which enables alignment and bonding at room temperature or a low temperature close to it. Both the cleaning effect is improved and highly accurate mounting is performed. It is to provide a mounting method and a mounting device that can be achieved.

[0007]

In order to solve the above-mentioned problems, a mounting method according to the present invention is a mounting method of cleaning at least one joint surface of objects to be joined and then joining the objects to be joined. The method is characterized in that cleaning is performed by irradiating the bonding surface with energy waves or energy particles while heating the object to be bonded. That is, heating is also used at the time of cleaning with energy waves or energy particles.

The cleaning of the joint surface by the irradiation of energy waves or energy particles is based on the physical action of removing the contamination layer on the surface mainly by the etching effect of the energy waves or energy particles to be irradiated. If the irradiation energy intensity is increased to enhance the effect, a large amount of electric charge tends to accumulate on the surface, and if it flows into the circuit of the article to be bonded made of semiconductor etc. at a dash, the circuit may be destroyed, that is, the charge. Up damage may occur.

However, in the mounting method according to the present invention,
Heating is also used at the time of cleaning, and at the surface of the joint surface to be cleaned by heating, the molecules of the metal or metal compound move more actively into the solid phase diffusion state, so the molecules of the contamination layer to be removed are one after another. , And even weak energy waves or energetic particles can be etched away sufficiently well. Ar plasma is used for this etching method, for example. Further, in the solid phase diffusion state, the bonds between the bonded molecules are easily released, and from this aspect, even weak energy waves or energetic particles can be sufficiently removed by etching. That is, the surface etching effect by the energy wave or the energy particles is physically enhanced by the combined use of heating.

As a result, since the contamination layer on the surface is sufficiently removed by the above cleaning, no special heating is required at the time of alignment and bonding following cleaning, and bonding at room temperature or a low temperature close to it is possible. Therefore, it is not affected by the thermal expansion caused by heating as in the conventional case, and it becomes possible to perform mounting with extremely high accuracy, for example, on the order of ± 0.2 μm in the submicron range.

The heating temperature used at the time of cleaning may be appropriately determined depending on the heat resistance of the object to be joined and the amount of the residual contamination layer allowed in the object to be joined,
In particular, it is preferably 100 ° C. or higher, which removes water that tends to cause adhesion of the contamination layer. Further, if activated too much by heating, the contamination in the chamber is likely to be redeposited. You can choose.

Further, it is preferable that the cleaning is performed in a reduced pressure atmosphere. The reduced pressure atmosphere can enhance the cleaning effect by the energy wave or the energy particles themselves, and the combined use of heating as in the present invention makes it possible to obtain a sufficiently excellent cleaning effect even at a weak energy level.

In the cleaning, an inert gas (for example, argon gas), a non-oxidizing gas (for example, nitrogen gas), a reducing gas (for example, hydrogen gas), a replacement gas (for example, a substituent such as a fluorine group) is used. It is preferable to carry out in any of the atmospheres (having gas). Also in this case, it is preferable to use the reduced pressure conditions together. In addition, in the method of removing the contamination layer by a chemical reaction such as the removal of organic substances by oxygen plasma or the removal of oxides by hydrogen plasma in contrast to the above-described etching method, heating during cleaning in such a gas atmosphere is also required. By using together,
The heating activates the surface to improve the reduction and substitution functions, and the hydrogen and carbon atoms in the contamination layer are replaced by H ₂ O and CO ₂
It becomes the gas of and becomes easy to be removed. Further, even in etching in an inert gas (for example, argon gas), surface molecules are easily ejected by heating, and the cleaning ability is improved. That is, by concurrently using heating during cleaning in these gas atmospheres, chemical reactions are promoted and the cleaning effect is further improved.

In the mounting method according to the present invention as described above, after the cleaning as described above is performed, the objects to be joined can be cooled and aligned, and then the objects to be joined can be joined together. For cooling, air cooling or, in some cases, cooling using a fluid refrigerant (for example, water cooling) can be applied. By cooling, it is possible to completely eliminate the influence of thermal expansion during alignment and joining in the conventional technique, and it is possible to achieve highly accurate mounting without distortion. As the cooling of the objects to be welded after washing, for example, it is possible to cool to room temperature. Here, the normal temperature refers to a temperature of the solder melting temperature (for example, about 180 ° C.) or lower to room temperature, and in consideration of removal of the influence of the thermal expansion, the room temperature to 100 ° C.
It is preferable to cool to a moderate temperature range.

Further, in the mounting method according to the present invention as described above, since a sufficiently high cleaning effect can be obtained while preventing the occurrence of charge-up, the occurrence of charge-up damage must be avoided. It is suitable for mounting, especially for semiconductors.

Also, in the mounting method according to the present invention,
The cleaning process involving heating, the alignment process of the objects to be bonded after cleaning, and the bonding process of the objects to be bonded after alignment may be performed in one chamber.
By doing this, a series of steps from cleaning to bonding
It becomes possible to carry out efficiently and quickly in substantially one mounting device.

Plasma, ion beam, atomic beam, radical beam, laser, etc. can be used as the above-mentioned energy wave or energy particles used for cleaning, but among them, it is easy to handle and control, and the cost of the apparatus. It is preferable to use plasma from the viewpoint of the simplicity of the structure and the structure and the surface of less charge-up damage.

The mounting apparatus according to the present invention is a mounting apparatus for cleaning at least one of the joint surfaces of the objects to be joined and then joining the objects to be joined together. It is characterized by having heating / cleaning means for cleaning the joint surface by irradiating energetic particles.

The mounting apparatus according to the present invention preferably further comprises means for reducing the pressure of the atmosphere during cleaning.
Further, it is preferable to further have a gas supply means for making the atmosphere for cleaning any atmosphere of inert gas, non-oxidizing gas, reducing gas, and replacement gas. Further, it is also preferable to further have a means for cooling the cleaned object.

This mounting apparatus is also particularly effective when the object to be cleaned is a semiconductor, since a sufficiently high cleaning effect can be obtained while preventing the occurrence of charge-up.

Further, in this mounting apparatus, the heating / cleaning means can perform the cleaning with heating, the alignment of the objects to be bonded after cleaning, and the bonding of the objects to be bonded after the alignment in one chamber. Alternatively, the alignment means and the joining means may be provided.

As the energy wave or energy particle to be used, plasma is particularly preferable as described above, and when plasma is used, the means for holding the object to be bonded serves both as the heating means and the electrode for plasma generation. It can be a structure.

Further, particularly when the above cleaning is performed under a reduced pressure atmosphere, it is preferable that at least one object to be bonded holding means is provided with electrostatic chuck means for electrostatically holding the object to be bonded. By using electrostatic chuck means,
The object to be bonded can be held without any problem even in a vacuum.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a mounting apparatus 1 according to an embodiment of the present invention. In the present embodiment, as the objects to be bonded to each other, one is the chip 2 and the other is the substrate 3. A plurality of electrodes 4 (two electrodes 4 are shown in FIG. 1) are provided on the chip 2, and the corresponding electrodes 5 are provided on the substrate 3.
Is provided. The chip 2 is held by the chip holding means 6 as one of the bonded object holding means, and the substrate 3 is held by the substrate holding means 7 as the other bonded object holding means. In this embodiment, the chip holding means 6 can be positionally adjusted in the Z direction (vertical direction), and the substrate holding means 7 is positioned in the X and Y directions (horizontal direction) and / or the rotation direction (θ direction). It can be adjusted.

The substrate holding means 7 as described above is generally mounted so as to be movable in parallel and / or rotatable.
If necessary, they may be mounted in a combination of them and lifting (movement in the Z direction). Also, the chip holding means 6
As for the side, not only the raising / lowering operation but also the parallel movement and / or
Alternatively, it may be in the form of a device capable of rotating.

In the above description, the chip 2 is, for example, an IC chip, a semiconductor chip, an optical element, a surface mount component, a wafer, or the like, whichever is on the side to be bonded to the substrate 3 regardless of its type or size. Say. The substrate 3 is
For example, resin substrate, glass substrate, film substrate, chip, wafer, etc.
It means everything on the side that is joined with.

In the present embodiment, the part for directly holding the chip 2 in the chip holding means 6 and the part for directly holding the substrate 3 in the substrate holding means 7 are formed in the electrode tools 8 and 9, respectively. It is configured so that it can function as a generating electrode. These electrode tools 8 and 9 are connected to a plasma generating power source 10 so that their polarities can be switched alternately, and the cleaning plasma 1 is applied to the bonding surface of the chip 2 and the bonding surface of the substrate 3 between the electrode tools 8 and 9.
1 can be irradiated.

A heater 12 as a heating means is built in the chip holding means 6, and when the bonding surface of the chip 2 is cleaned by the plasma, the chip 2 (the bonding surface)
It can be heated. Similarly, the substrate holding means 7 has a built-in heater 13 as a heating means,
When the bonding surface of the substrate 3 is cleaned by the plasma,
The substrate 3 (its bonding surface) can be heated.

In addition, in the present embodiment, in order to enable the alignment shown in FIG. 2 to be described later and the bonding shown in FIG. 3 to be performed in one chamber together with the cleaning described above, the entire apparatus is not enclosed. A local chamber 14 is provided so that the chip 2 and the substrate 3 which are arranged to face each other and the peripheral portion thereof can be locally and substantially sealed. The chamber 14 is fixed to the chip holding means 6 side, and the lower side of the chamber 14 is composed of an elastic member 15 which can be expanded and contracted. By closely contacting the substrate holding means 7 side, a closed space 16 can be formed. There is.

In the present embodiment, a vacuum pump 17 as a pressure reducing means is connected to the chamber 14, and the vacuum pump 17 is operated so that the inside of the closed space 16 surrounded by the chamber 14 is reduced to a predetermined pressure during the cleaning. It can be made into an atmosphere.

In the present embodiment, the inert gas supply means 18 is also connected to the chamber 14 in order to make the inside of the chamber 14 an inert gas atmosphere, particularly an argon gas atmosphere, during the cleaning with the plasma.

Further, in the present embodiment, the air-cooling type cooling means 19 and 20 are provided for the heaters 12 and 20, respectively, so that the temperature of the chip 2 and the substrate 3 can be promptly and forcibly lowered after the plasma cleaning using the above heating. It is built in on the back side of 13.

In the mounting apparatus 1 thus constructed, the chip 2 and the substrate 3 are arranged before the alignment and the bonding are performed.
The joint surface of is cleaned by plasma with heating. By heating, the surface of the cleaning surface is activated to the solid phase diffusion state, and the plasma is irradiated in that state, so even if the energy level of the plasma itself is suppressed to a low level, excellent etching for removing the contamination layer is achieved. The effect is obtained, and a high cleaning effect in which the contamination layer is sufficiently removed can be obtained without causing charge-up damage. That is, it is possible to obtain a high cleaning effect to the extent that normal temperature bonding can be performed at the bonding surface at the atomic level.

In addition, since the plasma cleaning is performed under a reduced pressure atmosphere in which the presence of air is sufficiently suppressed and in an argon gas atmosphere, plasma is easily generated and efficiently cleaned. . Moreover, adjustment of the current and voltage from the plasma generating power supply 10 and / or
By adjusting the supply amount of the argon gas, the intensity of the generated plasma can be easily and accurately controlled to the desired intensity, that is, the intensity that does not cause charge-up damage.

After the plasma cleaning accompanied by such heating, in the present embodiment, the chips 2 and the substrate 3 which have been heated are cooled to the room temperature or a temperature close thereto by the air cooling type cooling means 19 and 20, and the same. In the chamber 14, the alignment process shown in FIG. 2 and the joining process shown in FIG. 3 are provided.

For the alignment, as shown in FIG. 2, for example, an infrared camera inserted below is used as the recognition means 21 to read the recognition marks provided on the side of the substrate 3 and the side of the chip 2, and the relative marks between them are read. It is performed by controlling the position on the substrate holding means 7 side so that the position falls within a predetermined accuracy range. During this alignment,
The chip 2 and the substrate 3, and their holding means 6,
Since the temperature of 7 is lowered, the problem of deterioration of accuracy due to thermal expansion is avoided, and high-precision alignment is possible.

When the infrared camera is arranged below as described above to read the recognition mark, for example, a member capable of transmitting infrared rays (for example, to the back surface side of the substrate holding portion on the substrate holding means 7 side). A backup glass) is provided over the mark reading range, and the range is configured not to be blocked by the position adjusting means of the substrate holding means 7, thereby recognizing both the substrates 3 and chips 2 from the bottom. The mark can be read.

After the above-mentioned alignment, as shown in FIG. 3, for example, the chip 2 is lowered together with the chip holding means 6, and its electrode 4 is pressure-bonded to the electrode 5 of the substrate 3 to bond them. At this time, the bonding surface, that is, the surface of the electrode 4 of the chip 2 and the surface of the electrode 5 of the substrate 3 is kept in a state where the contamination layer is well removed by the plasma cleaning accompanied by the heating, so that the purpose is to dare. No special heating is required, and both bonding surfaces are firmly bonded at the atomic level at room temperature or a low temperature close to it. Since heating does not have to be performed at the time of bonding, the problem of accuracy deterioration due to thermal expansion can be avoided even during this bonding, high-accuracy bonding becomes possible, and finally a highly accurate and highly reliable mounted product can be obtained. Will be done.

[0039]

As described above, according to the mounting method and the mounting apparatus according to the present invention, heating is also used when cleaning the bonding surface by energy waves or energy particles. While lowering the energy level of energetic particles to prevent the occurrence of charge-up damage, the surface can be activated by heating and a sufficiently high cleaning effect can be obtained, without heating at or near room temperature. Can be joined to. Further, since the energy level can be lowered, the device cost and running cost can be reduced. The reliability of the bonded product can be secured by preventing the occurrence of charge-up damage, and extremely high mounting accuracy can be achieved by alignment and bonding at room temperature without heating.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a cleaning process of a mounting apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an alignment step in the mounting apparatus of FIG.

FIG. 3 is a schematic configuration diagram showing a joining step in the mounting apparatus of FIG.

[Explanation of symbols] 1 Mounting device 2 chips 3 substrates 4 chip electrodes 5 Substrate electrodes 6 Chip holding means 7 Substrate holding means 8, 9 electrode tool 10 Plasma generation power supply 11 plasma 12, 13 heater 14 chambers 15 Elastic member 16 enclosed space 17 Vacuum pump as pressure reducing means 18 Inert gas (argon gas) supply means 19, 20 Cooling means 21 Recognition means

Claims (18)

[Claims] 1. A mounting method in which at least one joint surface of the objects to be joined is cleaned and then the objects to be joined are joined together, and in the cleaning, the joining surfaces are irradiated with energy waves or energy particles while heating the objects to be joined. An implementation method characterized by being performed. 2. The object to be bonded is 100 to 500 during the cleaning.
The mounting method according to claim 1, wherein heating is performed to a temperature within a range of ° C. 3. The mounting method according to claim 1, wherein the cleaning is performed in a reduced pressure atmosphere. 4. The cleaning is performed with an inert gas, a non-oxidizing gas,
The mounting method according to claim 1, wherein the mounting method is performed in an atmosphere of either a reducing gas or a replacement gas. 5. The mounting method according to claim 1, wherein after the cleaning, the objects to be bonded are cooled and then aligned, and then the objects to be bonded are bonded to each other. 6. The mounting method according to claim 5, wherein the objects to be bonded are cooled to room temperature after the cleaning. 7. The mounting method according to claim 1, wherein the article to be cleaned is a semiconductor. 8. The cleaning process involving heating, the alignment process of the objects to be bonded after cleaning, and the bonding process of the objects to be bonded after the alignment are performed in one chamber. Implementation method described. 9. The mounting method according to claim 1, wherein the energy wave or the energy particle is plasma. 10. A mounting device for bonding at least one object to be bonded after cleaning the bonding surface of the object to be bonded,
A mounting apparatus comprising: heating / cleaning means for cleaning the bonding surface by irradiating the bonding surface with energy waves or energy particles while heating the bonding object. 11. The mounting apparatus according to claim 10, further comprising means for reducing the pressure of the cleaning atmosphere. 12. The method according to claim 10, further comprising a gas supply means for changing the atmosphere during cleaning to an atmosphere of any one of an inert gas, a non-oxidizing gas, a reducing gas and a replacement gas.
Mounting equipment. 13. The mounting apparatus according to claim 10, further comprising means for cooling the cleaned object to be bonded. 14. The object to be cleaned is a semiconductor,
The mounting apparatus according to claim 10. 15. The heating / cleaning means, the alignment means, and the joining means capable of performing the cleaning with heating, the alignment of the objects to be joined after the cleaning, and the joining of the objects to be joined after the alignment in one chamber. The mounting device according to claim 10, wherein the mounting device is provided. 16. The mounting device according to claim 10, wherein the energy wave or the energy particle is plasma. 17. The mounting apparatus according to claim 16, wherein the means for holding the object to be bonded serves as both the heating means and the electrode for plasma generation. 18. The mounting apparatus according to claim 10, wherein at least one of the object-to-be-bonded holding means includes electrostatic chuck means for electrostatically holding the object to be bonded.