CN1340852A - Method for manufacturing printed bumps on semiconductor carrier - Google Patents

Abstract

A method for manufacturing semiconductor carrier, especially the printed convex block on semiconductor wafer or substrate, includes such steps as covering the surface of wafer or printed convex block on substrate with heat-resistant and stable synthetic adhesive tape, perforating the synthetic adhesive tape at the position corresponding to under-bump metal (UBM) by laser, brushing tin paste in the holes by brush plate, high-temp reflow treatment to melt the tin paste, hardening to become welding ingot, tearing off the synthetic adhesive tape, and high-temp reflow treatment for the second time to form spherical convex block on UBM layer or substrate.

Description

Method for manufacturing printed bumps on semiconductor carrier

The invention relates to a method for manufacturing a printed bump on a semiconductor carrier, in particular to a method for manufacturing a printed bump on a semiconductor wafer or a substrate.

The new generation of high-end packaging technology is dominated by Ball-Grid-Array (BGA), Chip-Size/Scale-package (CSP), and Flip-Chip technologies. These technologies are mainly based on the flip-chip construction technology. In a broad sense, the flip-chip assembly technology generally refers to flipping the chip and bonding it through the metal conductor and the substrate in a face-down manner. Generally speaking, the technology of metal bump is relatively mature for metal conductors, and it is also widely used in mass-produced products. ) uses electroless nickel/gold (electroless Ni/Au) to form the under bump metallurgy (UBM) and then cooperates with printing to plant balls. The conventional main process is shown below:

First apply electroless nickel/gold on the aluminum (AL) on the surface of the wafer to form a UBM layer; coat a layer of photoresist on the surface of the crystal pattern and preheat it; The upper part is blocked by an appropriate mask and exposed and developed to form a blind hole at the position of the UBM layer; continue to use a brush plate to brush the solder paste into the blind hole, and the solder paste is melted by high temperature reflow soldering. Tin ingots, and then the photoresist is removed with chemicals and cleaned, leaving only the tin ingots raised on the wafer. After the second high-temperature reflow treatment, the tin ingots form spherical tin balls.

This conventional bumping process has disadvantages in the process of covering photoresist, photolithography and removing photoresist:

1. The photoresist needs to spend a hard time after covering;

2. In the photolithography imaging process, a mask for positioning imaging must be made additionally, which also increases the manufacturing cost;

3. After the first reflow process, the photoresist must be removed chemically or physically, and the whole procedure is more cumbersome and time-consuming;

In any industry, time spent is money spent. Aiming at the above-mentioned shortcomings of the conventional manufacturing process, the present invention applies a novel manufacturing process, which can effectively simplify the manufacturing process and maintain the production cost.

The object of the present invention is to provide a method for manufacturing printed bumps on semiconductor carriers, especially a method for manufacturing printed bumps on semiconductor wafers or substrates. The present invention uses synthetic adhesive tapes with good heat resistance and stability to replace Photoresist, the covering process is simple, it can be quickly pasted on the surface of the crystal pattern, and the laser positioning and drilling is controlled by the program. After printing solder paste and high temperature reflow, the second reflow can be performed by directly tearing off the tape, which can effectively Minimize the multi-channel process, save time and maintain solid state operation, no need to waste time waiting for cleaning and air drying of chemicals.

The purpose of the present invention is achieved in this way: a method for manufacturing printed bumps on a semiconductor carrier is to stick a synthetic adhesive tape on the surface of the carrier, form a cavity by laser perforation, and then fill the hole with solder paste by using a brush plate , After the solder paste is melted into solder ingots by high-temperature reflow treatment, the synthetic tape is torn off, and solder balls are formed after the second high-temperature reflow treatment. The process is as follows:

a. Forming the metal object to be coated on the surface of the carrier;

b. Lay synthetic tape on the surface of the carrier:

c. Laser perforation is applied at an appropriate position above the synthetic tape;

d. After laser perforation, make blind holes in the synthetic tape;

e. Use the brush board to brush the solder paste into the blind hole;

f. After high temperature reflow, the solder paste is melted into tin ingots;

g. The synthetic tape is torn off directly, leaving only the raised tin ingot on the carrier;

h. After the second high-temperature reflow treatment, the tin ingot forms a spherical tin ball on the metal layer under the bump.

The semiconductor carrier may be a semiconductor wafer, and the semiconductor carrier may also be a semiconductor substrate. The metal object to be coated may be an under-bump metal layer formed on the aluminum on the surface of the carrier. The metal object to be covered can also be a copper circuit.

The method for manufacturing printed bumps on semiconductor wafers or substrates provided by the present invention uses synthetic adhesive tapes with good heat resistance and stability to replace photoresists. Control laser positioning and drilling. After printing solder paste and high-temperature reflow, the second reflow can be performed by directly tearing off the tape. The cleaning and air drying time of the medicine. The present invention can also be applied to metal bump forming and solder coating process on substrates such as ball grid array (BGA).

Further describe the present invention in detail below in conjunction with accompanying drawing:

1a-1h are schematic diagrams of a conventional wafer metal bump forming process.

2a-2h are schematic diagrams of the wafer metal bump forming process of the present invention.

3a-3h are schematic diagrams of another embodiment of the present invention (copper contact bumping process of the substrate).

A brief description of the symbols in the figure:

1. Wafer, 11. Aluminum, 12. Under-bump metal layer UBM, 13. Polyimide, 14. Silicon; 2. Photoresist, 21. Blind hole, 2a, synthetic tape, 2a1, blind hole; 3. Cover, 4. Brush board, 5. Solder paste, 6. Tin ingot, 7. Solder ball, 8. Substrate, 81. Polyimide layer, 82. Copper circuit, 83. Synthetic tape, 831. Blind Hole, 84, brush plate, 85, solder paste, 86, tin ingot, 87, tin ball.

Please refer to FIGS. 1a-1h , which are schematic diagrams of a conventional wafer metal bump forming process. First apply electroless nickel/gold plating on the aluminum (AL) 11 on the surface of the wafer (wafer) 1 to form a UBM layer 12; coat a layer of photoresist (photo-resist) 2 on the surface of the crystal pattern and preheat it ; Use a suitable mask (Mask) 3 to block and apply exposure and development imaging on the top of the wafer, so that blind holes 21 are formed at the position of the UBM layer; continue to use the brush plate 4 to brush the solder paste 5 into the blind holes. High-temperature reflow melts the solder paste into tin ingot 6, and then removes the photoresist with chemicals and cleans it, leaving only the protruding tin ingot on the wafer. After the second high-temperature reflow treatment, the tin ingot That is, spherical solder balls 7 are formed.

In the conventional wafer metal bump forming process, the photoresist takes a long time to dry and harden after covering; and in the photolithography imaging process, it is necessary to make an additional positioning imaging mask, which also increases the manufacturing cost and the first reflow After treatment, the photoresist must be removed chemically or physically, and the whole process is more cumbersome and time-consuming.

Please refer to FIGS. 2a-2h, which are schematic diagrams of the wafer metal bump forming process of the present invention.

The manufacturing method of printing bumps on semiconductor wafers or substrates of the present invention is to paste the synthetic tape on the surface of the wafers, form concave holes by laser perforation, and then use a brush plate to fill the solder paste into the hole positions, and then reflow at high temperature After the solder paste is melted into a solder ingot, the synthetic tape is torn off, and the ball is formed after the second high-temperature reflow treatment.

Please refer to Figure 2a-2h, the manufacturing process is as follows:

a. Apply electroless nickel/gold plating on the aluminum (Al) 11 on the surface of the wafer 1 to form a UBM layer 12, as shown in FIG. 2a.

b. Paste the synthetic tape 2 a on the surface of the wafer 1 , as shown in FIG. 2 b .

c. Apply laser perforation at a proper position above the synthetic tape 2a (relative to the position of the UBM layer 12), as shown in FIG. 2c.

d. After laser perforation, make blind holes 2a1 in the synthetic tape 2a, as shown in FIG. 2d.

e. Use the brush board 4 to brush the solder paste 5 into the blind hole 2a1, as shown in FIG. 2e.

f. Solder paste 5 is melted into tin ingot 6 through high temperature reflow, as shown in FIG. 2f.

g. The synthetic tape 2a is directly torn off, leaving only the protruding tin ingot 6 on the wafer 1, as shown in FIG. 2g.

h. After the second high temperature reflow treatment, the tin ingot 6 forms a spherical tin ball 7 on the UBM layer 12 .

The present invention is not limited to the use of electroless nickel/gold plating to form the UBM layer 12 , and those who use other methods to form the UBM layer 12 are also applicable.

According to this process, the synthetic tape 2a is directly pasted on the wafer 1 in the process b, which is fast and convenient; and in the process c, the laser perforation method is used to directly punch holes in the synthetic tape 2a, and it is directly torn off after reflow After removing the synthetic tape 2a, the secondary reflow process can be carried out. The whole process is direct and fast, which can save a lot of production time.

Please refer to FIGS. 3a-3h , which are schematic diagrams of another embodiment of the present invention (balling process of copper contacts on the substrate).

The present invention can also be applied to bumping and solder coating on a substrate, and the manufacturing process is as follows:

a. Form a copper circuit 82 on the substrate 8, as shown in FIG. 3a.

b. Covering the substrate 8 with a synthetic adhesive tape 83, as shown in 3b.

c. Laser perforation is performed at an appropriate position above the synthetic tape 83 (relative to the position of the copper circuit 82), as shown in FIG. 3c.

d. After laser perforation, make blind holes 831 in the synthetic tape 83 , as shown in FIG. 36 .

e. Use the brush plate 84 to brush the solder paste 85 into the blind hole 831 , as shown in FIG. 3 e .

f. Solder paste 85 is melted into tin ingot 86 through high temperature reflow, as shown in FIG. 3f.

g. The synthetic tape 83 is torn off directly, leaving only the protruding tin ingot 86 on the substrate 8, as shown in FIG. 3g.

h. After the second high-temperature reflow treatment, the tin ingot 86 forms a spherical tin ball 87 or solder coating on the copper block 83 .

Although the present invention is disclosed above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection of the invention should be defined with reference to the content in the claims.

Claims (5)

1, a kind of manufacture method of printed convex block on semiconductor carrier, be to be attached to carrier surface with synthetic adhesive tape, form pothole with the laser perforation means, continue and tin cream is inserted hole location with brush board, after high temperature reflow processing makes tin cream dissolve into the weldering ingot, tear this synthetic adhesive tape again off, form the tin ball after the high temperature reflow second time is handled, its processing procedure is:

A, on the surface of carrier, form and desire the metal object that coated;

B, post synthetic adhesive tape at carrier surface:

C, above synthetic adhesive tape the appropriate location, impose the laser perforation;

D, after laser perforation, get blind hole at synthetic adhesive tape;

E, utilize brush board that tin cream brush is inserted in the blind hole;

F, make tin cream melt into tin slab through the high temperature reflow;

G, should synthesize adhesive tape again and directly tore off, only stay the tin slab of projection on the carrier;

H, after second time high temperature reflow is handled, this tin slab promptly forms spherical tin ball on metal level below the projection.

2, the manufacture method of a kind of printed convex block on semiconductor carrier as claimed in claim 1 is characterized in that: described semiconductor carrier is a semiconductor crystal wafer.

3, the manufacture method of a kind of printed convex block on semiconductor carrier as claimed in claim 1 is characterized in that: described semiconductor carrier is a semiconductor substrate.

4, the manufacture method of a kind of printed convex block on semiconductor carrier as claimed in claim 1 is characterized in that: the described metal object of desiring to be coated can be metal level below the projection that forms on the aluminium on the surface of carrier.

5, the manufacture method of a kind of printed convex block on semiconductor carrier as claimed in claim 1 is characterized in that: the described metal object of desiring to be coated also can be and is copper wire.

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