JP3123707B2 - Solder bump formation method, solder bump connection method and pressure jig - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a solder bump, a method of connecting a solder bump, and a pressing jig, which enable high-precision and high-density terminal connection and can form a solder bump reliably. It is about.

[0002]

2. Description of the Related Art As a conventional high-density terminal connection method between a semiconductor chip and a wiring board, a flip-chip method is generally known (reference example: Handbook for Semiconductor Packaging Technology, published by Science Forum Co., Ltd.). 100μm diameter
By using solder bumps of the appropriate degree, terminals can be taken out from the entire surface of the semiconductor chip, enabling high-density connections. In addition, the short connection length minimizes stray capacitance and parasitic inductance at the connection. Therefore, it is becoming an important technology as a terminal connection method for a high-speed LSI.

However, the conventional flip-chip method requires a process of forming a semiconductor element or the like on a semiconductor substrate and then directly forming a solder layer on an electrode terminal, so that the process is complicated, yield is low, and productivity is low. There was a problem that it was inferior. For this reason, a method has been devised in which a large number of solder bumps are formed on a carrier substrate, the solder bumps are transferred onto the electrodes of a semiconductor element, and flip-chip connected to the substrate (Japanese Patent Laid-Open No. Hei 5-166880). ). FIG. 9 shows schematic steps of this method.

In FIG. 9, after a dot-shaped solder layer 2 is patterned on a transfer carrier chip 1 having poor solder wettability (a), the transfer carrier chip 1 is placed on the electrodes 4 of the semiconductor chip 3. By aligning (b) and melting the solder, the solder layer 2 on the transfer carrier chip 1 is transferred onto the electrodes 4 of the semiconductor chip 3 to form solder bumps 5 (c). Further, the method is such that the semiconductor chip 3 is aligned with the electrodes 7 on the wiring board 6 (d), and the solder bumps 5 are reflowed to perform flip-chip connection (e).

In the step of transferring the solder layer 2 on the transfer carrier chip 1 onto the electrodes 4 of the semiconductor chip 3, even if the thickness of the semiconductor chip 3 varies or the pressing axis is inclined, As shown in FIG. 10, a method of pressing the transfer carrier chip 1 and the semiconductor chip 3 with a pressing jig 8 having a tip portion formed of a convex curved surface with a view to reliably transferring the layer 2 is provided. It has been devised. Further, as shown in FIG. 11, in the step of flip-chip connecting the semiconductor chip 3 on the wiring board 6, similarly to the above-mentioned transfer step, a convex pressing jig 8 is formed.
A method of pressing the semiconductor chip 3 and the wiring substrate 6 has been devised (Japanese Patent Application No. 8-254431).

[0006]

However, FIG.
As shown in FIG. 7, when the transfer carrier chip 1 and the semiconductor chip 3 become large, the conventional method using the convex pressing jig 8 causes uniform pressurization due to the influence of the warpage of the large carrier chip 9 and the like. The solder bumps 5 are completely transferred to the electrodes 4 of the large semiconductor chip
Also, it is difficult to completely connect the large-sized semiconductor chip 10 to the wiring board 6 and other semiconductor chips in the step of connecting the solder bumps 5 in the solder bump 5 connection process.

According to the present invention, even if a transfer carrier chip or a semiconductor chip is enlarged, the solder layer can be completely transferred to the electrode of the semiconductor chip to form a solder bump or can be connected to a wiring board by a bump. It is an object of the present invention to provide a method of forming a solder bump, a method of connecting a solder bump, and a pressing jig.

[0008]

According to the present invention, there is provided a method for forming a solder bump, comprising forming a plurality of dot-shaped solder layers having a desired shape and pitch on a carrier chip having poor wettability with solder; Positioning the electrode portion of the semiconductor chip at a position facing the solder layer, and heating and melting the solder layer, thereby transferring the solder layer to the electrode portion of the semiconductor chip to form a solder bump. In the method, in the step of transferring the solder layer, after the solder layer of the carrier chip and the electrode of the semiconductor chip are aligned and temporarily fixed by pressing, after the step of applying a flux, the melting point of the solder is equal to or lower than the melting point. Temperature and larger than the carrier chip or semiconductor chip
The pressurized surface is composed of a flexible sheet with a large area,
Pressurization with an internal structure controlled to a desired pressure
Tool , for a desired time, subsequent to the step of pressurizing and heating the carrier chip or the semiconductor chip, performing a step of heating the solder layer at a temperature equal to or higher than the melting point of the solder for a desired time, thereby forming the electrodes of the semiconductor chip on the solder layer. To form a solder bump.

[0009]

Further, a solder bump is formed by the above-described method for forming a solder bump, and when the semiconductor chip on which the solder bump is formed is connected to a wiring board or another semiconductor chip by a bump, the semiconductor chip is connected to the wiring board or another semiconductor chip. after temporarily fixed by inter-electrode Shi the positioning pressure of the semiconductor chip, after the step of applying the flux, in the solder melting point below the temperature and the carrier chip and half
Pressing surface due to flexible sheet with larger area than conductor chip
Is constructed, the structure is sealed and the inside is at the desired pressure.
With a pressure jig controlled to a desired time, following the step of pressing and heating the semiconductor chip or the wiring board,
The bump connection is performed by performing a heat treatment at a temperature equal to or higher than the melting point of the solder for a desired time.

[0011]

The pressing jig of the present invention is used when transferring solder to a semiconductor chip or when connecting a semiconductor chip to a wiring board, and comprises a rigid base and a flexible sheet. And a front end portion which is attached to a sealed structure to make the inside of the sealed structure a predetermined pressure.

[0013]

Method of forming solder bumps of the embodiment of the present invention, as showing the basic structure 1 and 2, in the step of transferring the solder layer 2, at a temperature below the melting point of the solder, and the holder A pressing jig 13 (FIG. 1) in which a flexible resin 12 is mounted on the tip of the pressing member 11, or a pressing jig 15 controlled to a desired pressure by the holder 11 and the flexible sheet 14.
In FIG. 2, after the step of pressurizing and heating the large carrier chip 9 or the large semiconductor chip 10 for a desired time, a step of performing a heat treatment at a temperature equal to or higher than the melting point of the solder for a desired time is performed. Thus, the solder layer 2 is transferred to the large semiconductor chip 10 to form a solder bump.

In the method of connecting solder bumps according to the present invention, in the step of transferring the solder layer 2, in addition to the step of performing heat treatment for a desired time while applying pressure and the step of performing heat treatment subsequent to this step, FIGS. 4 Basic configuration
As shown in the figure, the step of bump-connecting the large semiconductor chip 10 to a wiring board or another semiconductor chip 6 is also a step similar to the step of transferring the solder layer 2, and at a temperature equal to or lower than the melting point of the solder, And the holder 11
With the pressing jig 13 (FIG. 3) in which the flexible resin 12 is attached to the tip of the sheet, or the pressing jig 15 (FIG. 4) controlled to a desired internal pressure by the holder 11 and the flexible sheet 14. After the step of pressurizing and heating the large semiconductor chip 10 or the wiring board for a period of time, the bump connection is performed by performing a step of heating for a desired time at a temperature equal to or higher than the melting point of the solder. Things.

[0015] The present invention, in the step of transferring the solder layer, by the solder melting point temperature below One or,
In pressing jig 13 having a sealed flexible sheet structure internal controlled to a desired pressure so as to have a da Iyafuramu function, desired time, pressure to have large semiconductor chip 10 with the large carrier chip By the step of applying pressure and heating, the solder layer formed on the large carrier chip can be brought into contact with the electrodes of the large semiconductor chip facing each other at a uniform pressure without a gap.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
5 and 6 and an embodiment of the present invention is shown in FIGS .

[0017] An example <br/> about the method of forming solder bumps in FIG. As a substrate material having poor wettability with solder, for example, a film-like thick film resist (for example, DuPont product name "Liston" or liquid resist) is formed on a large carrier chip 9 made of silicon, titanium, molybdenum, or the like. (For example, an AZ-based resist manufactured by Shipley Co.), a solder is formed by a vacuum evaporation method or the like, and then the resist is removed by a lift-off technique to form a solder layer 2 (a). Carrier chip 9
The solder layer 2 formed on the large-sized semiconductor chip 10 is aligned with the electrode 4 and temporarily fixed by a slight pressure.
This is placed on a carrier jig 17 and a flux 16 is applied so as to permeate the solder layer 2 (b). Next, a pressing jig 13 in which a flexible resin 12 is attached to the tip of the holder 11
Is applied to the back surface of the large-sized carrier chip 9 and, on a hot plate 18 set at a temperature equal to or lower than the melting point of the solder layer 2, under a condition controlled to a desired time, pressure and temperature. A pressure / heat treatment is performed (c). Here, as the flexible resin 12, a silicone resin having excellent heat resistance can be used. Following this step,
Heat treatment is performed for a desired time at a temperature equal to or higher than the melting point of the solder to form a solder bump 5 for transfer (d). Finally, the flux 16 is washed and removed using an organic solvent to complete the solder bump 5 (e).

FIG. 6 shows a step of connecting the large semiconductor chip 10 having the transferred solder bumps 5 to the wiring board 6 by bump connection. The solder bumps 5 of the large semiconductor chip 10 (a) having the transferred solder bumps 5 are positioned on the electrodes 7 of the wiring board 6 and temporarily fixed by a slight pressure. And apply a flux 16 so as to penetrate the solder bumps 5 (b). Next, the back surface of the large-sized semiconductor chip 10 is pressed by using a pressing jig 13 (FIG. 1) in which a flexible resin 12 is attached to the tip of the holder 11 in the same manner as that used in the previous transfer step. Then, a pressurizing / heating process is performed on the hot plate 18 set at a temperature equal to or lower than the melting point of the solder bump 5 under conditions controlled to a desired time, pressure and temperature (c). Subsequent to this step, a heat treatment is performed under a condition controlled at a desired temperature and time, which is equal to or higher than the melting point of the solder, to perform bump connection (d). Finally, the flux 16 is washed and removed using an organic solvent to complete the bump connection (e).

FIG. 7 shows that in the transfer step, the back surface of the large carrier chip 9 is pressed by using a pressing jig 15 controlled to a desired internal pressure by the holder 11 and the flexible sheet 14, and the solder bump 5 3 shows a process of forming solder bumps in which pressure and heat treatments are performed under conditions controlled to a desired time, pressure and temperature on a hot plate 18 set to a temperature equal to or lower than the melting point. Here, as the flexible sheet 14, a heat-resistant film material such as fluororesin or polyimide resin can be used as a resin material, and a film-like aluminum or stainless steel can be used as a metal material.

FIG. 8 shows that a large semiconductor chip 10 having solder bumps 5 transferred thereto by a pressing jig 15 controlled to a desired internal pressure by a holder 11 and a flexible sheet 14 is flipped onto a wiring board 6. It shows a step of connecting chips.

In the present embodiment, the shape of the carrier chip or the semiconductor chip is not limited, and the shape of the wafer before cutting into chips is reduced by the method described in the present embodiment. It is self-evident that it can be applied up to something as large as.

[0022]

As described above, according to the present invention, in the step of transferring a solder layer, after a flux is applied to a carrier chip and a semiconductor chip, the flux is applied at a temperature lower than the melting point of the solder and the carrier chip or the semiconductor chip. Bigger
The pressurized surface is composed of a flexible sheet with a large area,
Pressurization with an internal structure controlled to a desired pressure
After the step of performing pressure and heat treatment under the conditions controlled to the desired time, pressure, and temperature with the tool , under the conditions controlled to the desired temperature and time at a temperature equal to or higher than the melting point of the solder Since the heat treatment step is performed in two stages, the pressing axis is not perpendicular to the surface of the carrier chip or the semiconductor chip, and even if the semiconductor chip has a thickness variation, It can be expected that the solder layer formed thereon is brought into contact with the electrodes of the opposing semiconductor chip at a substantially uniform pressure without generating a gap. By such a method, all the solder layers can be transferred to the electrodes of the semiconductor chip, and it is possible to form the transfer solder bumps.

Also, in the step of connecting a semiconductor chip to a wiring board or another semiconductor chip by a bump, the carrier chip is substantially similar to the step of transferring a solder layer.
Flexible sheet with a larger area than chips and semiconductor chips
The pressurized surface is composed of
After the step of pressing the semiconductor chip or the wiring board for a desired time with a pressing jig controlled to a desired pressure, a step of performing a heat treatment at a temperature higher than the melting point of the solder for a desired time is performed. The bump connection between the semiconductor chip and the wiring board or another semiconductor chip can be completely performed.

[Brief description of the drawings]

[1] is a diagram showing a basic configuration of the present invention, shows the outline of the formation process of the solder bumps for transcription with pressurizing jig here.

[Figure 2] is a diagram showing a basic configuration of the present invention, shows the outline of the formation process of the solder bumps for transcription with pressurizing jig here.

[Figure 3] is a diagram showing a basic configuration of the present invention, shows the schematic process of bump connection using the pressurizing jig here.

[Figure 4] is a diagram showing a basic configuration of the present invention, shows the schematic process of bump connection using the pressurizing jig here.

FIG. 5 is a view showing one embodiment of a method of forming a solder bump according to the related art in the same technical field as the present invention.

FIG. 6 is a view showing one embodiment of a method of connecting solder bumps according to a related technique in the same technical field as the present invention.

7 is a diagram showing the real施例forming method according solder bumps to the present invention.

8 is a diagram showing the real施例connection method according solder bumps to the present invention.

FIG. 9 is an explanatory diagram of a process of forming a solder bump for transfer according to a conventional technique.

FIG. 10 is a view for explaining a state of pressurization in a process of forming a transfer solder bump according to a conventional technique.

FIG. 11 is a view for explaining a state of pressurization in a step of forming a solder bump for transfer according to a conventional technique.

FIG. 12 is a diagram for explaining a state of pressurization in a step of forming a solder bump for transfer according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transfer carrier chip 2 Solder layer 3 Semiconductor chip 4 Electrode (on a semiconductor chip) 5 Solder bump 6 Wiring board 7 Electrode (on a wiring board) 8 Pressing jig of convex shape 9 Large carrier chip 10 Large semiconductor chip 11 Holder 12 Flexible resin 13 Pressure jig (flexible resin type) 14 Flexible sheet 15 Pressure jig (flexible sheet type) 16 Flux 17 Carrier jig 18 Hot plate

Claims (3)

(57) [Claims] A plurality of dot-shaped solder layers having a desired shape and pitch are formed on a carrier chip having poor wettability with solder, and an electrode portion of the semiconductor chip is positioned at a position facing the solder layer. In the method of forming a solder bump by transferring the solder layer to an electrode portion of the semiconductor chip by heating and melting the solder layer, in the step of transferring the solder layer, After aligning the solder layer and the electrodes of the semiconductor chip and temporarily fixing them by pressing, after a step of applying a flux, at a temperature equal to or lower than the melting point of the solder, and having an area larger than that of the carrier chip or the semiconductor chip . Flexible sheet
The pressurized surface is configured, the structure is sealed and the inside is desired
With a pressing jig controlled to a pressure of, for a desired time, following the step of pressing and heating the carrier chip or the semiconductor chip, by performing a step of heating for a desired time at a temperature equal to or higher than the melting point of the solder A method for forming a solder bump, comprising transferring the solder layer to an electrode of the semiconductor chip to form a solder bump. 2. A method of forming a solder bump according to claim 1 , wherein the solder bump is formed, and the semiconductor chip on which the solder bump is formed is mounted on a wiring board.
Or when connecting bumps to other semiconductor chips,
Connect the semiconductor chip to the wiring board or other semiconductor chip.
After positioning the gap and temporarily fixing by pressing,
After the step of applying solder, the temperature below the melting point of the solder
And larger than the carrier chip or the semiconductor chip.
The pressurized surface is composed of a flexible sheet with a large area,
Pressurization with an internal structure controlled to a desired pressure
Tool, for the desired time, the semiconductor chip or the wiring board
After the step of pressurizing and heating
By performing a heat treatment at the above temperature for a desired time.
Connection <br/> method of solder bumps, characterized by bump connection Ri. 3. When transferring solder to a semiconductor chip,
Or an additional element used to connect the semiconductor chip to the wiring board.
A pressure jig, with a rigid base and a flexible sheet
And a closed end that is attached to the
Pressing jig, characterized in that the inner to the predetermined pressure.