CN106158678B

CN106158678B - Method for detecting wafer bonding quality

Info

Publication number: CN106158678B
Application number: CN201510131035.3A
Authority: CN
Inventors: 李兵; 游宽结; 章国伟; 侯元琨
Original assignee: Semiconductor Manufacturing International Shanghai Corp
Current assignee: Semiconductor Manufacturing International Shanghai Corp
Priority date: 2015-03-24
Filing date: 2015-03-24
Publication date: 2020-03-06
Anticipated expiration: 2035-03-24
Also published as: CN106158678A

Abstract

The invention provides a method for detecting wafer bonding quality, which comprises the following steps: providing a wafer subjected to wafer bonding, and forming a first wafer back protection film on the front surface of the wafer; turning the wafer over, and forming a second wafer back protection film on the back of the wafer; cutting off the first wafer back protection film and the second wafer back protection film at a certain distance along the edge of the wafer to form an air bag for wrapping the wafer; and carrying out wafer bonding quality detection on the wafer wrapped by the air bag. According to the invention, when the wafer bonding quality detection is implemented by adopting ultrasonic scanning, the judgment of the detection result caused by the influence of the deionized water permeating into the edge of the wafer can be avoided.

Description

Method for detecting wafer bonding quality

Technical Field

The invention relates to a semiconductor manufacturing process, in particular to a method for detecting wafer bonding quality.

Background

After the front-end semiconductor device manufacturing process and part of the back-end semiconductor device manufacturing process are performed to form the front-end semiconductor device and the multilayer interconnection metal structure electrically connected with the front-end semiconductor device in the wafer, wafer dicing needs to be performed to obtain the crystal grains. Bonding between the wafers is performed before wafer dicing is performed. The existing wafer bonding process generally belongs to eutectic bonding, such as copper-copper bonding, indium-gold bonding, tin-gold bonding, gold-gold bonding, etc., and the bonding method needs to form a bonding pad made of copper, lead, indium, gold, etc. on one of two wafers for wafer bonding, and form a bonding material corresponding to the position of the bonding pad on the other wafer. After the wafer bonding process is performed, as shown in fig. 1, the bonding pads 102 on the first wafer 100 and the bonding material 103 on the second wafer 101 are fused together to form a cavity 104.

In testing the bonding quality of the wafer, an ultrasonic scanning (C-SAM) method is generally used, in which two wafers (e.g., a first wafer 100 and a second wafer 101 shown in fig. 1) bonded together are immersed in deionized water, and the positions of the two wafers where bonding defects exist are found by ultrasonic scanning. As shown in fig. 1, since a gap exists between the edges of the two wafers, the deionized water may be immersed between the two wafers along the gap, which may affect the detection result. As shown in fig. 2, the black-colored sites 200 at the edge of the wafer are not sites where bonding defects exist, but sites filled with deionized water.

Therefore, a method is needed to solve the above problems.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for detecting the bonding quality of a wafer, which comprises the following steps: providing a wafer subjected to wafer bonding, and forming a first wafer back protection film on the front surface of the wafer; turning the wafer over, and forming a second wafer back protection film on the back of the wafer; cutting the first wafer back protection film and the second wafer back protection film along the edge of the wafer at a certain distance to form an air bag for wrapping the wafer; and carrying out wafer bonding quality detection on the wafer wrapped by the air bag.

In one example, the wafer bond is a eutectic bond including a copper-copper bond.

In one example, the wafer bonding quality inspection is performed using ultrasonic scanning.

In one example, a protective film used in a wafer back thinning process is attached to the front side of the wafer to form the first wafer back protective film, and the thickness of the first wafer back protective film is 0.08mm-0.15 mm.

In one example, a protective film used in a wafer back thinning process is attached to the back of the wafer to form the second wafer back protective film, and the thickness of the second wafer back protective film is 0.08mm-0.15 mm.

In one example, after the cutting is performed, the first and second wafer back protection films extend outwards along the edge of the wafer by a distance of 3.0mm-9.0 mm.

According to the invention, when the wafer bonding quality detection is implemented by adopting ultrasonic scanning, the judgment of the detection result caused by the influence of the deionized water permeating into the edge of the wafer can be avoided.

Drawings

The following drawings of the invention are included to provide a further understanding of the invention. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

In the drawings:

fig. 1 is a schematic cross-sectional view of a device obtained after wafer bonding according to the prior art;

FIG. 2 is a diagram illustrating a wafer bonding quality inspection result according to the prior art;

FIG. 3 is a flowchart illustrating steps performed in sequence by a method according to an exemplary embodiment of the present invention;

FIGS. 4A-4D are schematic views of states of wafers respectively obtained from sequential steps of a method according to an exemplary embodiment of the present invention;

fig. 5 is a schematic diagram of a detection result obtained after detecting the bonding quality of the wafer according to the method of the exemplary embodiment of the invention.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention.

In order to provide a thorough understanding of the present invention, detailed steps will be set forth in the following description in order to explain the method for detecting wafer bonding quality as set forth in the present invention. It will be apparent that the invention may be practiced without limitation to specific details that are within the skill of one of ordinary skill in the semiconductor arts. The following detailed description of the preferred embodiments of the invention, however, the invention is capable of other embodiments in addition to those detailed.

It will be understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[ exemplary embodiments ]

Referring to fig. 3 and 4A-4D, steps performed in sequence and states of the respectively obtained wafers are shown according to a method of an exemplary embodiment of the present invention.

First, as shown in fig. 4A, step 301 is executed to provide a wafer subjected to wafer bonding, and form a first backside protection film (BG tape film) on the front side of the wafer. As an example, a protective film commonly used in a wafer back thinning process may be attached to the front surface of the wafer to form a first back wafer protective film, and the thickness may be 0.08mm to 0.15 mm.

Next, as shown in fig. 4B, step 302 is performed to turn the wafer upside down and form a second backside protection film on the backside of the wafer. As an example, a protective film commonly used in a wafer back thinning process may be attached to the back of the wafer to form a second backside protective film, and the thickness may be 0.08mm to 0.15 mm.

Next, as shown in fig. 4C, step 303 is executed to cut the first and second backside protection films along the edge of the wafer by a predetermined distance, so as to form an air bag 400 for wrapping the wafer as shown in fig. 4D. By way of example, the first and second wafer back protection films extend outwardly along the edge of the wafer by a distance of 3.0mm-9.0 mm.

Then, step 304 is performed to perform wafer bonding quality inspection on the wafer wrapped by the air bag 400. As an example, the wafer bonding quality inspection was performed by ultrasonic scanning, and the inspection result shown in fig. 5 was obtained without occurrence of black marks due to the deionized water permeating into the edge of the wafer.

To this end, the process steps performed by the method according to the first exemplary embodiment of the present invention are completed. According to the invention, when the wafer bonding quality detection is implemented by adopting ultrasonic scanning, the judgment of the detection result caused by the influence of the deionized water permeating into the edge of the wafer can be avoided.

Note that, before wafer bonding is performed, a front-end semiconductor device and a multilayer interconnection metal structure electrically connecting the front-end semiconductor device are formed in the wafer, and the front-end device refers to a device formed before performing a back-end manufacturing process of the semiconductor device, and a specific structure of the front-end device is not limited herein. The front-end device includes a gate structure including, as an example, a gate dielectric layer and a gate material layer sequentially stacked from bottom to top. Forming side wall structures on two sides of the gate structure, forming source/drain regions in the semiconductor substrate on two sides of the side wall structures, and forming a channel region between the source/drain regions; forming self-aligned silicide on the top of the gate structure and the source/drain region; forming an interlayer insulating layer, and forming a contact hole in the interlayer insulating layer to expose the salicide; forming a contact plug in the contact hole; forming a first layer of metal wiring electrically connecting the contact plugs; an inter-metal insulating layer is formed to cover the first layer of metal wiring. The specific number of layers of the multilayer interconnection metal structure is determined according to the structure of the semiconductor device and the function to be realized. The wafer bonding method is generally eutectic bonding, such as copper-copper bonding, indium-gold bonding, tin-gold bonding, gold-gold bonding, and the like, and the bonding method requires that a pad made of copper, lead, indium, gold, or the like is formed on one of two wafers on which wafer bonding is performed, a bonding material corresponding to the pad is formed on the other wafer, and a gap is formed between the two wafers after wafer bonding. Therefore, no matter which bonding method is adopted, as long as a gap exists between two wafers after wafer bonding, the method provided by the invention can be applied to detect the wafer bonding quality.

The present invention has been illustrated by the above embodiments, but it should be understood that the above embodiments are for illustrative and descriptive purposes only and are not intended to limit the invention to the scope of the described embodiments. Furthermore, it will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that many variations and modifications may be made in accordance with the teachings of the present invention, which variations and modifications are within the scope of the present invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A method of detecting wafer bonding quality, comprising:

providing a wafer subjected to wafer bonding, and forming a first wafer back protection film on the front surface of the wafer;

turning the wafer over, and forming a second wafer back protection film on the back of the wafer;

cutting the first wafer back protection film and the second wafer back protection film along the edge of the wafer at a certain distance to form an air bag for wrapping the wafer;

and carrying out wafer bonding quality detection on the wafer wrapped by the air bag by adopting ultrasonic scanning.

2. The method of claim 1, wherein the wafer bond is a eutectic bond including a copper-copper bond.

3. The method of claim 1, wherein the wafer bonding quality inspection is performed using ultrasonic scanning.

4. The method as claimed in claim 1, wherein the first back side protective film is formed by attaching a protective film used in a wafer back side thinning process to the front side of the wafer, and the thickness of the protective film is 0.08mm to 0.15 mm.

5. The method as claimed in claim 1, wherein the second backside protection film is formed by attaching a protection film used in a wafer backside thinning process to the backside of the wafer, and has a thickness of 0.08mm to 0.15 mm.

6. The method as claimed in claim 1, wherein the first and second backside protection films extend outwardly along the edge of the wafer by a distance of 3.0mm to 9.0mm after the performing of the cutting.