KR101377004B1

KR101377004B1 - Particle for forming through hole electrode and forming method of through hole electrode using the same

Info

Publication number: KR101377004B1
Application number: KR1020110058982A
Authority: KR
Inventors: 유봉영; 좌용호; 진상현
Original assignee: 한양대학교 에리카산학협력단
Priority date: 2011-06-17
Filing date: 2011-06-17
Publication date: 2014-03-26
Also published as: KR20120139267A

Abstract

The present invention relates to a through-electrode forming particle for forming a through-electrode without problems due to thermal expansion and thermal contraction, Filling material formed in the center; And a conductive material layer surrounding the outside of the filler, wherein the thermal expansion rate of the filler is smaller than that of the conductive material layer.
The present invention has the effect of forming the through-electrode without the problem of lateral growth and thermal expansion and thermal contraction caused by electrolytic deposition by using particles having a small thermal expansion coefficient therein.
In addition, since the conductive material layer uses particles having a structure surrounding the filler, the conductive material layer is easily melted and connected to each other, and the filler is evenly dispersed in the through electrode, thereby improving the performance of the through electrode and the ability to cancel the thermal stress of the filler. have.

Description

Particle for forming through-electrode and method for forming through-electrode using same {PARTICLE FOR FORMING THROUGH HOLE ELECTRODE AND FORMING METHOD OF THROUGH HOLE ELECTRODE USING THE SAME}

The present invention relates to a particle for forming a through electrode and a method for forming a through electrode, and more particularly, to a particle and a method for forming a through electrode without a problem caused by thermal expansion or thermal contraction.

In the semiconductor process, a wafer stacking technique using three-dimensional wiring is required for high density and high reliability packaging, and a high aspect ratio through electrode must be formed on a substrate to implement the technique. This is called TSV (Through-Silicon-Via) in a silicon substrate, and much research has been made.

Such through electrodes are generally formed through a wet electrolytic deposition process using vias formed in vias formed on the substrate by laser, drill, etching, or the like.

Chemical vapor deposition using titanium or copper is generally used as a method of forming seeds in vias, but seeds formed by chemical vapor deposition are formed not only on the bottom of the via but also on the side, and the seeds deposited on the side are electrolytically deposited. Large pores are often formed inside the penetrating electrode by causing lateral growth in the process.

FIG. 8 is a schematic diagram showing a cross-sectional structure in which mushroom defects of an electrode part are generated in a process after wet electrolytic deposition.

Since wet electrolytic deposition of the penetrating electrode proceeds in a water-based electrolyte solution, the process temperature is usually at room temperature, and is flattened by CMP over an overburden region inevitably plated on the silicon substrate 100 during deposition. It becomes a state. However, as the temperature increases in an additional semiconductor process, a portion of the through electrode 200 expands, and a mushroom defect 202 rising in the form of a mushroom may occur. Mushroom defects can be a fatal obstacle in subsequent BEOL processes.

In addition, since a metal material such as copper used in the through electrode 200 has a large difference in thermal expansion coefficient between the substrate 100 and the substrate, the thermal stress is generated between the substrate 100 and the through electrode 200 according to a change in temperature. do.

9 shows the damage to the through electrode due to thermal stress. The linear thermal expansion coefficients of copper used for the penetrating electrode 200 and silicon used as the substrate 100 are 16.5 ppm / ° C. and 2.6 ppm / ° C., respectively. Therefore, a large thermal stress acts on the through electrode 200 according to the change of temperature, and damage may occur. When the damage is severe, the through electrode 200 is short-circuited by the crack 500.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to provide a particle and a method for forming a through electrode without problems caused by thermal expansion and thermal contraction.

Particle for forming the through-electrode according to the present invention for achieving the above object, the filler formed in the center; And a conductive material layer surrounding the outside of the filler, wherein the thermal expansion rate of the filler is smaller than that of the conductive material layer.

According to the present invention, the thermal expansion and thermal contraction of the through electrode can be offset by using a filler that is a material exhibiting a thermal expansion rate smaller than that of the conductive material layer.

In addition, when the filler is placed inside and the conductive material layer constituting the through electrode is later filled with vias in the via structure, since the conductive material layers are in contact with each other inside the via, the conductive material layer is melted to form the through electrode. Can be formed. In addition, the filler is uniformly dispersed in the through electrode, and the effect of offsetting the performance and thermal stress of the through electrode is excellent.

In this case, the melting point of the filler is preferably higher than the melting point of the conductive material layer, the filler is preferably at least one material selected from materials such as Si, SiO2, B ₂ O ₃ , the thermal expansion coefficient of the filler is greater than 0 and 2.6ppm It is preferable that it is a range lower than / degreeC.

The present invention can control the amount of fillers dispersed in the through electrode by adjusting the ratio of the filler and the conductive material layer, the volume ratio of the preferred filler and the conductive material layer is 2: 8 ~ 8: 2 range.

The through electrode forming method of the present invention is a method of forming a through electrode by filling a via formed in a substrate with a conductive material, the through electrode forming particles comprising a filler formed in the center and a conductive material layer surrounding the outside of the filler. Filling the vias; Melting and connecting the conductive material layers to each other, wherein the thermal expansion rate of the filler is smaller than the thermal expansion rate of the conductive material layer.

The filling of the through electrode forming particles into the via may be performed by filling a via containing a paste for forming the electrode through the squeegee or filling the via with an ink including the through electrode forming particles. . In particular, an ink including particles for forming a through electrode may be injected into a via by an inkjet printing method.

In the case of using a paste or ink containing the through-electrode forming particles, it is preferable to further include evaporating and removing materials other than the through-electrode-forming particles filled in the vias before melting the conductive material layers and connecting them to each other.

According to the present invention configured as described above, through-particles having a small thermal expansion rate can be used therein, so that the through electrode can be formed without the problem of lateral growth and thermal expansion and thermal contraction occurring during the electrolytic deposition process. It works.

In addition, since the conductive material layer uses particles having a structure surrounding the filler, the conductive material layer is easily melted and connected to each other, and the filler is evenly dispersed in the through electrode, thereby improving the performance of the through electrode and the ability to cancel the thermal stress of the filler. have.

1 is a schematic diagram showing a cross-sectional structure of the through-electrode forming particles according to an embodiment of the present invention.
2 to 7 are schematic diagrams showing a process of forming a through electrode according to an embodiment of the present invention.
FIG. 8 is a schematic diagram showing a cross-sectional structure in which mushroom defects of an electrode part are generated in a process after wet electrolytic deposition.
9 is a view showing a damage to the through electrode due to the thermal stress.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the accompanying drawings, embodiments of the present invention will be described in detail.

1 is a schematic diagram showing a cross-sectional structure of the through-electrode forming particles according to an embodiment of the present invention.

The through electrode forming particle of the present embodiment has a core-shell structure composed of a filler 12 formed in the center and a conductive material layer 14 surrounding the outside.

The filler 12 is dispersed in the through electrode to offset the thermal expansion and thermal contraction of the through electrode. Therefore, the thermal expansion rate of the filler 12 is smaller than the thermal expansion rate of the conductive material layer 14. In addition, since the through electrode is formed by melting the conductive material layer 14, the melting point of the filler 12 should be higher than the melting point of the conductive material layer 14.

The filler 12 may cancel the thermal expansion rate of the through electrode by using silicon (Si), which is commonly used as a substrate, and silica (SiO 2), and the like, and melt the conductive material layer 14 because the melting point is high. It is advantageous to form through electrodes.

The conductive material layer 14 is a part made of a conductive material forming a through electrode. The conductive material layer 14 may be copper which is a material of a general through electrode.

The conductive material layer 14 is melted during the formation of the through electrode and is connected to the other conductive material layer 14. In this embodiment, the conductive material layer 14 is positioned outside to form a core-shell structure, thereby conducting the conductive material inside the via. The material layers 14 are in contact with each other to facilitate the connection between the conductive material layers 14.

In addition, the core-shell structure has an advantage in that the filler 12 is evenly distributed on all parts of the through electrode in the process of connecting the conductive material layer 14.

In the present embodiment, the size of the filler 12 may be determined according to the size of the through electrode, and the volume ratio of the filler 12 and the conductive material layer 14 may be adjusted to adjust the amount of the filler 12 included in the through electrode. I can regulate it.

At this time, the volume ratio of the preferred filler 12 and the conductive material layer 14 is in the range of 2: 8 ~ 8: 2. This is because if the volume ratio of the filler 12 is greater than 80%, the performance of the penetrating electrode may be degraded. If the volume ratio of the filler 12 is less than 20%, the offset effect by the filler 12 may not appear.

2 to 7 are schematic diagrams showing a process of forming a through electrode according to an embodiment of the present invention.

2 shows a via formed in the substrate 100. This embodiment is a case of forming a through-hole via, but the present invention is not limited to this form, and can be applied to the case of forming a trench-type via.

3 and 4 show the via filling the through-electrode forming particle 10 of the present invention.

As described above, the through-electrode forming particle 10 is a core-shell structured particle composed of a central filler 12 and an external conductive material layer 14. Therefore, any method of filling the via of the particulate matter may be used. In this embodiment, a method of using a squeegee and an inkjet printing method will be described.

Figure 3 shows the via filling the via electrode forming particles using a squeegee. First, a paste 20 including the through electrode forming particles 10 is made, and the paste 20 is pushed by the squeegee 24 to fill the inside of the via. At this time, a separate screen 22 is used to fill the paste to the top of the via.

Figure 4 shows the via-filled particles for forming the through-electrode by the inkjet printing method. First, the ink 30 including the through-electrode forming particles 10 is formed and discharged through the nozzle of the inkjet 34 device to fill the ink 30 in the via.

FIG. 5 shows the evaporation of materials other than the through electrode forming particles in the vias.

When the through-electrode forming particle 10 is filled in the via by the method of FIG. 3 or 4, in addition to the through-electrode forming particle 10, a material forming the paste 20 and the ink 30 is also located in the via. . Since these materials may act as impurities when forming the through electrode, it is better to remove them. Since the materials are mainly in a fluid state, they can be evaporated.

6 shows a state in which a through electrode is formed by melting a conductive material layer of particles for forming a through electrode.

The through electrode forming particles 10 apply heat to the substrate 100 filled with vias to melt and connect the conductive material layer 14 to form the through electrodes 200.

As shown in FIG. 5, since the conductive material layers 14 are in contact with each other due to the core-shell structure, the through electrode forming particles 10 are easily melted and connected to the conductive material layers 14. In addition, in the core-shell structure, since the filler 12 is located inside, the filler 12 is evenly distributed in the via, so that the filler 12 is also inside the through electrode 200 as shown in FIG. It is evenly distributed.

7 shows the final form of the through electrode on the substrate.

The excess copper layer formed on the front and rear surfaces of the substrate 100 is precisely ground with CMP to expose both sides of the through electrode 200 to complete the through electrode 200. In this embodiment, since the through electrode 200 is formed in the through via, the excess copper layer and the back side silicon substrate of the front surface of the substrate 100 are scraped off, but the trench via is used. There may be differences.

The through-electrode formed through the above process fills the material of particles in the process of filling the via with a conductive material, so that there is no problem of lateral growth occurring in the electroplating process, so that no large pores are formed therein.

Furthermore, since the filler having a low thermal expansion rate is evenly distributed in the through electrode made of a material having a higher thermal expansion rate than the substrate, problems due to thermal expansion and thermal contraction do not occur in the forming step and the post-forming step of the through electrode.

While the present invention has been described through the preferred embodiments, the above-described embodiments are merely illustrative of the technical idea of the present invention, and various changes may be made without departing from the technical idea of the present invention. Those of ordinary skill will understand. Therefore, the scope of protection of the present invention should be construed not only in the specific embodiments but also in the scope of claims, and all technical ideas within the scope of the same shall be construed as being included in the scope of the present invention.

10: particle for forming a through electrode 12: filler
14: conductive material layer 20: paste
22: Screen 24: Squeegee
30: ink 34: inkjet
100: substrate 200: through electrode
202: Mushroom Defect 500: Crack

Claims

Filler formed in the center;
It includes a conductive material layer surrounding the outside of the filler,
Particles for forming a through-electrode, characterized in that the thermal expansion rate of the filler is less than the thermal expansion rate of the conductive material layer.

The method according to claim 1,
Particles for forming a through electrode, characterized in that the filler is at least one material selected from Si, SiO 2 and B ₂ O ₃ .

The method according to claim 1,
Particles for forming a through-electrode, characterized in that the thermal expansion coefficient of the filler is greater than 0 and less than 2.6ppm / ℃.

The method according to claim 1,
Particles for forming a through electrode, characterized in that the melting point of the filler is higher than the melting point of the conductive material layer.

The method according to claim 1,
Particle ratio for forming a through electrode, characterized in that the volume ratio of the filler and the conductive material layer ranges from 2: 8 to 8: 2.

A method of forming a through electrode by filling a via formed in a substrate with a conductive material,
Filling through vias with the through-electrode forming particles including a filler formed at a center and a conductive material layer surrounding the outside of the filler;
Melting and connecting the conductive material layers to each other;
The thermal expansion rate of the filler is less than the thermal expansion rate of the conductive material layer forming method.

The method of claim 6,
And filling the via electrode forming particles into the via, filling the via using a squeegee with a paste including the through electrode forming particles.

The method of claim 6,
The filling of the through electrode forming particles into the vias may include injecting ink including the through electrode forming particles into the vias.

The method according to claim 8,
And a method of injecting the ink into the via is an inkjet printing method.

The method according to any one of claims 7 to 9,
And evaporating a material other than the through-electrode forming particles filled in the via before the step of melting and connecting the conductive material layer to each other.

A device comprising the particles of claim 1 in a via.