CN109904114B

CN109904114B - Laser processing method of through hole

Info

Publication number: CN109904114B
Application number: CN201910127720.7A
Authority: CN
Inventors: 陈洁
Original assignee: Shenzhen Xinghan Laser Technology Co Ltd
Current assignee: Shenzhen Xinghan Laser Technology Co Ltd
Priority date: 2019-02-26
Filing date: 2019-02-26
Publication date: 2021-03-19
Anticipated expiration: 2039-02-26
Also published as: CN109904114A

Abstract

The invention provides a laser processing method for a through hole. The laser-activated copper layer can prevent the upper through hole diameter gap from being larger during secondary drilling and etching, and overcomes the upper part of the through hole caused by one-step direct drilling in the prior art. The aperture is too wide to meet the needs of a larger aspect ratio; and the activated copper layer can be used as a seed layer for subsequent electroplating, and the copper layer activated by laser has a large surface roughness and good adhesion. focus.

Description

Laser processing method of through hole

Technical Field

The invention relates to the field of semiconductor workpiece processing, belongs to the classification number of H01L23/00, and particularly relates to a laser processing method of a through hole.

Background

In a semiconductor manufacturing process, through holes are often needed to realize the upper and lower interconnection between substrates or devices. Smaller aspect ratio (cross-sectional) vias have not been able to meet size requirements due to the shrinking dimensions. As shown in fig. 3, during the laser drilling process, due to the high temperature at the portion (top surface of the substrate 10) where the under etching starts, the under etching is too fast, and the sidewall portion of the upper portion thereof is also subjected to the continuous high temperature, for example, if the under etching is continued according to the situation shown in fig. 3, the aperture of the through hole position of the top surface portion of the substrate 10 is much larger than that of the through hole position of the bottom surface portion of the substrate. This is extremely disadvantageous in practical production.

Disclosure of Invention

Based on solving the above problems, the present invention provides a laser processing method of a through hole, comprising the steps of:

(1) providing a semiconductor substrate to be drilled with a front surface and a back surface which are opposite;

(2) utilizing laser to drill and etch a blind hole on the substrate, wherein the blind hole does not penetrate through the substrate and has a first aperture D;

(3) filling activatable copper organic matters into the blind holes;

(4) irradiating the blind hole by using the laser to volatilize organic matters in the activatable copper organic matters and leave an activated copper layer on the side wall of the blind hole;

(5) continuously performing underetching on the bottom of the blind hole by using the laser until the blind hole penetrates through the substrate to form a through hole, wherein the through hole has a second aperture r;

(6) and filling a conductive substance in the through hole to form a final through hole.

According to the embodiment of the present invention, the energy of the laser in the step (4) is smaller than that of the laser in the step (5).

According to an embodiment of the invention, wherein the first aperture D > the second aperture r.

According to an embodiment of the present invention, wherein D is 10 μm or less and 25 μm or less, r is 5 μm or less and 15 μm or less.

According to an embodiment of the invention, the thickness of the activated copper layer is less than or equal to 2 μm.

According to an embodiment of the present invention, the filling of the conductive substance in the step (6) includes electroplating copper, electroplating nickel, and the like.

According to an embodiment of the invention, the roughness of the activated copper layer is greater than 0.05 μm.

According to an embodiment of the present invention, the specific method for forming the through hole in the step (5) includes: and increasing the energy of the laser to enable the laser beam to be aligned to the bottom of the blind hole, wherein the activated copper layer serves as a protective layer to prevent the laser from further ablating the side wall of the blind hole until the laser completely bores and erodes through the substrate.

The invention has the following advantages: the laser activated copper layer can prevent the aperture difference of the upper through hole from being larger during secondary underetching, and overcomes the defect that the aperture of the upper through hole is too wide due to one-step direct drilling in the prior art and can not meet the requirement of larger aspect ratio; the activated copper layer can be used as a seed layer for subsequent electroplating, and the laser activated copper layer has high surface roughness and good adhesion.

Drawings

Fig. 1-7 are schematic diagrams of a laser processing method of a via hole of the present invention.

Detailed Description

The invention aims to provide a method for processing a through hole with a high aspect ratio.

Referring to fig. 1 to 7, the laser processing method of a via hole of the present invention includes the steps of:

referring to fig. 1, a semiconductor substrate 10 to be drilled is provided, having opposite front and back surfaces; the substrate 10 is typically a silicon substrate, and may also be an arsenic-containing substrate, a gallium nitride substrate, or the like, on which active devices, such as MOS or the like, may be formed, or passive devices, such as MIM capacitors, resistors, or the like, may be formed. The preformed through holes are typically through holes.

Referring to fig. 2, a blind hole 11 is etched on the substrate 10 by laser drilling, the blind hole 11 does not penetrate through the substrate 10 and has a first aperture D; the first aperture D is generally smaller than the conventional through hole, the bottom end of the blind hole is smaller, and the aperture thereof is not separately described. The laser undercutting process adopts a conventional helium-neon laser and the like.

Referring to fig. 3, activated copper organics 12 are filled in the blind holes 11; the organic portion of the activatable copper organic compound 12 can be thermally volatilized by the energy of the laser, and the complex of copper can be reduced to form copper by the laser. The filling can be performed by deposition, spin coating or coating.

Referring to fig. 4 and 5, the blind via 11 is irradiated with the laser, so that the organic compound in the activatable copper compound 12 is volatilized, and an activated copper layer 15 is left on the side wall of the blind via 11; as shown in fig. 4, the laser 13 may be identical to the laser used in fig. 2, except that the power and energy are different, which in fig. 4 emits a laser light 14, the energy of which laser light 14 is less than the energy of which blind via 11 in fig. 2 is formed. The thickness of the activated copper layer 15 is less than or equal to 2 μm, the roughness of the copper layer 15 obtained by the activation method tends to be large, which is advantageous for adhesion, and the roughness of the activated copper layer 15 is greater than 0.05 μm.

Referring to fig. 6, continuing to drill the bottom of the blind via 11 by using the laser 14 until penetrating through the substrate 10 to form a through hole 16, wherein the through hole 16 has a second aperture r; the laser energy corresponds to the laser energy used to form blind via 11 in fig. 2, but is greater than the activation laser energy used in fig. 4. In the specific operation process, after the copper layer is activated and the organic matter is volatilized, the energy of the laser is increased to enable the laser beam to be aligned to the bottom of the blind hole 11, and the activated copper layer 15 serves as a protective layer to prevent the laser from further ablating the side wall of the blind hole 11 until the laser completely erodes and penetrates through the substrate 10. Wherein the first aperture D > the second r; wherein D is more than or equal to 10 mu m and less than or equal to 25 mu m, and r is more than or equal to 5 mu m and less than or equal to 15 mu m.

Referring to fig. 7, the through hole 16 is filled with a conductive material to form a final via hole 17. The filling of the conductive material includes copper electroplating, nickel electroplating, etc.

Of course, the above method is preferably used for a thinner substrate, and when the substrate is thicker, a plurality of blind holes may be formed by multiple times of undercutting, filling with the activatable copper organic 12, and activating to form a plurality of copper layers interconnected up and down to form a deeper through hole.

Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.

Claims

1. A laser processing method of a through hole, comprising the steps:

(1) providing a semiconductor substrate to be drilled, having opposite front and back surfaces;

(2) using laser drilling to etch blind holes on the substrate, the blind holes do not penetrate the substrate and have a first aperture D;

(3) Filling the activatable copper organic matter in the blind hole;

(4) irradiating the blind hole with the above-mentioned laser, so that the organic matter in the activatable copper organic matter is volatilized, and an activated copper layer is left on the side wall of the blind hole;

(5) Continue to drill and etch the bottom of the blind hole by using the above-mentioned laser until it penetrates the substrate to form a through hole, and the lower half of the through hole has a second aperture r;

(6) Filling the through hole with a conductive material to form a final through hole.

2 . The laser processing method of the through hole according to claim 1 , wherein the energy of the laser in the step (4) is smaller than the energy of the laser in the step (5). 3 .

3 . The laser processing method of the through hole according to claim 1 , wherein: the first aperture D>the second aperture r. 4 .

4 . The laser processing method of the through hole according to claim 1 , wherein: 10 μm≦D≦25 μm, and 5 μm≦r≦15 μm. 5 .

5 . The laser processing method of the through hole according to claim 1 , wherein the thickness of the activated copper layer is less than or equal to 2 μm. 6 .

6 . The laser processing method of the through hole according to claim 1 , wherein filling conductive substances in the step (6) includes electroplating copper and electroplating nickel. 7 .

7 . The laser processing method of the through hole according to claim 1 , wherein the activated copper layer has a roughness greater than 0.05 μm. 8 .

8 . The laser processing method of the through hole according to claim 1 , wherein the specific method of forming the through hole in the step (5) comprises: increasing the energy of the laser so that the laser beam is aimed at the blind hole. 9 . At the bottom, the activated copper layer acts as a protective layer to prevent further laser ablation of the sidewall of the blind hole until it is completely drilled through the substrate.