Ultrathin crystal thinning and cutting process utilizing tempered glass
Technical Field
The invention relates to the field of wafer processing, in particular to an ultrathin crystal thinning and cutting process by using tempered glass.
Background
In daily life, the progress of semiconductor technology is largely reflected in the reduction of feature size, and as the feature size is reduced, the number of transistor circuits per unit area is increased, and the functions are enhanced accordingly. However, while the integration density is greatly improved, the heat source starts to form a concentrated phenomenon on the chip, and how to reduce the thermal resistance of the device and perform heat dissipation and cooling of the device becomes a key problem. In fact, one of the solutions to heat dissipation of components is grinding thinning.
The thickness of the active area of the devices and connecting circuits on the wafer is typically 5 to 10 μm, and in order to ensure their functionality, a certain support thickness is required, which has a limit of 20 to 30 μm for the thickness of the wafer. But this thickness actually occupies only a small portion of the entire wafer thickness, and the remaining thickness of the substrate is only sufficient to ensure that the silicon wafer has sufficient strength during fabrication, testing, packaging, and shipping. After the integrated circuit on the wafer is manufactured, the back of the silicon wafer needs to be thinned to reach the required thickness.
In the prior art, a bonded glass carrier plate is usually used for thinning the back of a wafer, and after the back process is finished, the ultra-thin wafer is attached to a soft polymer film for debonding and cutting the wafer. During wafer dicing, although the periphery of the polymer film is fixed by metal, the polymer film has weak stress, so when the wafer is as thin as less than 30um (8 inch and 12 inch wafers), the glass carrier is debonded, or the adhesive layer is removed, the wafer is very easy to crack.
Disclosure of Invention
In order to solve the above-mentioned drawbacks of the background art, the present invention provides a process for thinning and cutting an ultra-thin crystal by using a strengthened glass, wherein the chemically strengthened ultra-thin glass is used for secondary bonding to replace a conventional polymer film cutting mold frame, so that the wafer can be effectively prevented from being cracked after the glass carrier is debonded and bonded.
The purpose of the invention can be realized by the following technical scheme:
an ultrathin crystal thinning and cutting process utilizing tempered glass comprises the following steps:
s1, completing the front process of the wafer;
s2, bonding the glass carrier plate on the front surface of the wafer temporarily;
s3, thinning the back of the wafer by grinding and etching, and then finishing the back process of the wafer;
s4, bonding the ultrathin glass carrier plate on the back of the wafer;
and S5, debonding and removing the glass carrier plate on the front surface of the wafer, cleaning and removing the adhesive layer, and then finishing the cutting of the wafer.
Further preferably, the front surface process of the wafer includes a photolithography process, an ILD process, an ion implantation process, a metal process and an etching process.
Further preferably, the glass carrier plate in the step S2 is a normal silicate glass plate with a thickness of 400-800 μm, and the adhesive layer of the bonded glass plate in the step S2 has a thickness of more than 30 μm.
Further preferably, the wafer back side process includes a photolithography process, an ion implantation process, and a metal process.
Further preferably, the ultra-thin glass carrier plate in step S4 is a high alumina silica glass plate with a thickness of less than 100 μm, and the adhesive layer bonding the ultra-thin glass carrier plate in step S4 has a thickness of less than 30 μm.
The invention has the beneficial effects that:
the invention adopts the technology of twice bonding and debonding to process the wafer ultrathin wafer, and the strengthened ultrathin glass carrier plate is used for replacing the traditional cutting die frame for the second bonding so as to ensure that the crystal grains can be packaged on the glass carrier plate with strength and flexibility, thereby ensuring that the ultrathin wafer (crystal grains) can not generate the phenomenon of cracking.
Drawings
The invention will be further described with reference to the accompanying drawings.
FIG. 1 is a schematic view of the process of step S1 according to the present invention;
FIG. 2 is a schematic view of the process of step S2 according to the present invention;
FIG. 3 is a schematic view of the process of step S3 according to the present invention;
FIG. 4 is a schematic view of the process of step S4 according to the present invention;
fig. 5 is a schematic view of the process of step S5 according to the present invention.
In the figure:
1-wafer, 2-glass carrier plate, 3-ultrathin glass carrier plate and 4-crystal grain.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "opening," "upper," "lower," "thickness," "top," "middle," "length," "inner," "peripheral," and the like are used in an orientation or positional relationship that is merely for convenience in describing and simplifying the description, and do not indicate or imply that the referenced component or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be considered as limiting the present invention.
Example 1
An ultrathin crystal thinning and cutting process utilizing tempered glass comprises the following steps:
s1, completing the front process of the wafer;
s2, temporarily bonding a common silicate glass plate with the thickness of 500 mu m on the front surface of the wafer through an adhesive layer with the thickness of 60 mu m;
s3, thinning the back of the wafer by grinding and etching, and then finishing the back process of the wafer;
s4, bonding a high-alumina-silica glass plate with the thickness of 100 mu m on the back surface of the wafer through an adhesive layer with the thickness of 20 mu m;
and S5, debonding and removing the glass carrier plate on the front surface of the wafer, cleaning and removing the adhesive layer, and then finishing the cutting of the wafer.
The front side process of the wafer includes a photolithography process, an ILD process, an ion implantation process, a metal process, and an etching process.
The wafer backside process includes a photolithography process, an ion implantation process, and a metal process.
Example 2
An ultrathin crystal thinning and cutting process utilizing tempered glass comprises the following steps:
s1, completing the front process of the wafer;
s2, temporarily bonding a common silicate glass plate with the thickness of 600 mu m on the front surface of the wafer through an adhesive layer with the thickness of 50 mu m;
s3, thinning the back of the wafer by grinding and etching, and then finishing the back process of the wafer;
s4, bonding a high-alumina-silica glass plate with the thickness of 50 mu m on the back surface of the wafer through an adhesive layer with the thickness of 20 mu m;
and S5, debonding and removing the glass carrier plate on the front surface of the wafer, cleaning and removing the adhesive layer, and then finishing the cutting of the wafer.
The front side process of the wafer includes a photolithography process, an ILD process, an ion implantation process, a metal process, and an etching process.
The wafer backside process includes a photolithography process, an ion implantation process, and a metal process.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed.