CN112670183A

CN112670183A - Repairing method of bonded and stripped lithium niobate wafer and lithium niobate wafer

Info

Publication number: CN112670183A
Application number: CN202011466815.0A
Authority: CN
Inventors: 刘昆; 周赤; 吉贵军; 张大鹏; 王兴龙; 黄杭东; 陆龙钊
Original assignee: Zhuhai Guangku Technology Co ltd
Current assignee: Zhuhai Guangku Technology Co ltd
Priority date: 2020-12-14
Filing date: 2020-12-14
Publication date: 2021-04-16

Abstract

The invention provides a repairing method of a bonded and stripped lithium niobate wafer and the lithium niobate wafer. The repairing method comprises heating and annealing the bonded and stripped raw material lithium niobate wafer; and polishing the stripping surface of the raw material lithium niobate wafer, wherein the polishing depth is equal to or more than half of the ion implantation depth extension range. The repairing method can repair the bonded and stripped lithium niobate wafer, so that the waste lithium niobate wafer is reused, and waste is avoided.

Description

Repairing method of bonded and stripped lithium niobate wafer and lithium niobate wafer

Technical Field

The invention relates to the field of photoelectric semiconductor materials, in particular to a method for repairing a bonded and stripped lithium niobate wafer and the lithium niobate wafer.

Background

The lithium niobate single crystal has excellent transmission performance, electro-optic performance, nonlinear optical performance and piezoelectric performance, and is widely applied to optical communication, data center optical interconnection and high-frequency filtering devices. The nanometer thin film lithium niobate single crystal on other material substrate has the excellent characteristics, and can be used for integrated devices, which is a novel hopeful integrated optical material. However, growing lithium niobate single crystal thin films on other substrate materials has proven difficult to achieve, whereas mechanical slicing techniques have difficulty in producing thin films of nanometer-scale thickness.

The lithium niobate single crystal film prepared by using Smart-Cut technology in recent years makes the mass production of thin film lithium niobate wafers possible. The method comprises the following general steps: firstly, polishing the surface of a raw material lithium niobate wafer to meet the requirements of wafer bonding, simultaneously preparing another carrier wafer, such as a silicon (Si) wafer, preparing a buffer layer, such as silicon dioxide (SiO2), on the carrier wafer, polishing to enable the buffer layer to meet the requirements of wafer bonding, then performing ion implantation with specific energy and specific measurement, such as helium ions (He +), on the polished surface of the raw material lithium niobate wafer, then bonding the polished surface of the raw material wafer and the polished surface of the carrier wafer, heating the two wafers after bonding to enable the implanted ions to be compounded into micro bubbles, separating the raw material lithium niobate wafer after expansion, and leaving a lithium niobate film on the carrier wafer.

When the method is used for manufacturing the monocrystalline lithium niobate thin film on the bearing wafer, the raw material lithium niobate is stripped from the composite wafer and is discarded, so that the raw material is greatly wasted, and the product cost is increased.

Disclosure of Invention

The first purpose of the invention is to provide a repairing method of a bonded and peeled lithium niobate wafer, which can repair the bonded and peeled lithium niobate wafer, so that the waste lithium niobate wafer is reused and waste is avoided.

The second purpose of the invention is to provide a lithium niobate wafer manufactured by the repairing method.

In order to achieve the first object, the invention provides a method for repairing a bonded and peeled lithium niobate wafer, which comprises the steps of heating and annealing a bonded and peeled raw material lithium niobate wafer; and polishing the stripping surface of the raw material lithium niobate wafer, wherein the polishing depth is equal to or more than half of the ion implantation depth extension range.

In a preferred embodiment, the heating temperature is 250 ℃ to 350 ℃.

In a further embodiment, the heating time is from 0.5 hours to 3 hours.

In order to achieve the second object, the present invention provides a lithium niobate wafer manufactured by the above repairing method, wherein the lithium niobate wafer comprises a lithium niobate wafer main body and an annealing repairing layer located on the lithium niobate wafer main body.

The method has the advantages that for the raw material lithium niobate wafer after bonding stripping, a small amount of ions exist outside the ion implantation depth spreading range, bubbles cannot be formed, only some crystal lattices are damaged, and the crystal lattice damage caused by ion implantation is repaired by adopting a heating annealing mode, so that the waste lithium niobate wafer is reused, and waste is avoided. Meanwhile, the raw material lithium niobate wafer can be repaired by repeating the steps after bonding and stripping each time until the thickness of the raw material lithium niobate wafer is reduced to be inoperable, so that the utilization rate of the raw material is greatly improved.

Drawings

Fig. 1 is a schematic structural diagram of a lithium niobate single crystal thin film chip in an embodiment of the method for repairing a bonded and peeled lithium niobate wafer according to the present invention.

Fig. 2 is a schematic structural diagram of a bonded and peeled lithium niobate wafer in an embodiment of the repairing method of a bonded and peeled lithium niobate wafer of the present invention.

Fig. 3 is a relation between ion energy and ion implantation depth extension range in an embodiment of the repairing method of the bonded and peeled lithium niobate wafer according to the present invention.

Fig. 4 is a schematic structural diagram of an embodiment of a lithium niobate wafer of the present invention.

The invention is further explained with reference to the drawings and the embodiments.

Detailed Description

Referring to fig. 1, the method for preparing a lithium niobate single crystal thin film chip includes the steps of: and preparing a dielectric layer 2 on the carrier wafer 1 by a film coating or direct oxidation method. Next, the surface of the dielectric layer 2 as a buffer layer is optically polished. Then, ions are implanted into the optical-level surface of the raw material lithium niobate wafer 3, the ions are implanted by helium ions (He +), the ions penetrate through the optical-level surface and stay on the wafer surface after the preset depth, and then an ion layer 4 is formed, and the ion layer 4 divides the raw material lithium niobate wafer 3 into a raw material lithium niobate wafer main body 5 and a lithium niobate thin layer 6. After ion implantation is completed, optical polishing is performed on the dielectric layer 2 to remove surface unevenness possibly caused by ion bombardment, so as to meet the requirement of wafer bonding. And then, carrying out wafer bonding on the lithium niobate thin layer 6 and the dielectric layer 2. And then, heating the bonded composite wafer to 200-230 ℃, thereby improving the strength of the bonding interface between the lithium niobate thin layer 6 and the dielectric layer 2. And then, heating the bonded composite wafer to 250-350 ℃ to enable injected ions to be gasified and polymerized into micro bubbles, separating the composite wafer at the ion layer 4 under the action of the bubbles, and reserving a lithium niobate thin layer 6 with a specific thickness on the dielectric layer 2 of the bearing wafer 1. And (3) carrying out optical polishing treatment on the surface of the lithium niobate thin layer 6 to ensure that the thickness and the surface smoothness of the lithium niobate thin layer meet the requirements of optical waveguides.

In the raw material lithium niobate wafer 3 subjected to the ion implantation process, ions penetrate the surface of the wafer to a certain depth and stay in the ion layer 4, but not all the ions stay at the same depth but are distributed in a certain depth range, which is called an ion implantation depth extension range. During the heating process, the vaporization of the ions also occurs within the ion implantation depth spread range. For example, as shown in fig. 3, the ion implantation depth spread ranges around 180 nm at an ion implantation energy of 600 KeV. After the ion layer is vaporized, the ion layer is peeled off and peeled off at approximately the middle of the depth of the ion layer, and the peeled raw material lithium niobate wafer 3 and the remaining lithium niobate thin film on the surface of the handle wafer each leave a defect layer having a thickness of approximately half the ion implantation depth extension range, and as shown in fig. 2, the defect layer of the raw material lithium niobate wafer 3 is a rough peeled surface 31 on the raw material lithium niobate wafer 3. And some small amount of ions exist outside the ion implantation depth extension range, bubbles cannot be formed, and only some crystal lattices are damaged.

The method for repairing the bonded and peeled raw material lithium niobate wafer 3 includes the following steps.

Firstly, heating and annealing the bonded and stripped raw material lithium niobate wafer 3 at the temperature of 250-350 ℃ for 0.5-3 hours.

Then, the stripping surface 31 of the raw material lithium niobate wafer 3 is polished to a depth equal to or more than half of the ion implantation depth extension range, so that the flatness and the smoothness of the wafer reach the wafer bonding requirements.

The repairing step can be repeatedly carried out in the preparation process of the lithium niobate single crystal thin film chip, namely the step is repeated after bonding and peeling each time, the raw material lithium niobate wafer 3 is repaired until the thickness of the raw material lithium niobate wafer 3 is reduced to be inoperable, and therefore the utilization rate of raw materials is greatly improved.

The lithium niobate wafer 7 shown in fig. 4 is manufactured by the above repairing method, and the lithium niobate wafer 7 includes a lithium niobate wafer main body 71 and an annealed repairing layer 72 located on the lithium niobate wafer main body 71. The annealing repair layer 72 is a portion of the lithium niobate wafer 3, which is subjected to the crystal lattice damage outside the ion implantation depth spreading range and is repaired by annealing.

Finally, it should be emphasized that the above-described preferred embodiments of the present invention are merely examples of implementations, not limitations, and various changes and modifications may be made by those skilled in the art, without departing from the spirit and scope of the invention, and any changes, equivalents, improvements, etc. made within the spirit and scope of the present invention are intended to be embraced therein.

Claims

1. A method for repairing a bonded and peeled lithium niobate wafer is characterized by comprising the following steps:

heating and annealing the bonded and stripped raw material lithium niobate wafer;

and polishing the stripping surface of the raw material lithium niobate wafer, wherein the polishing depth is equal to or more than half of the ion implantation depth extension range.

2. The method for repairing a bonded and peeled lithium niobate wafer according to claim 1, wherein:

the heating temperature is 250 ℃ to 350 ℃.

3. The method for repairing a bonded and peeled lithium niobate wafer according to claim 1 or 2, wherein:

the heating time is 0.5 to 3 hours.

4. A lithium niobate wafer produced by the repair method according to any one of claims 1 to 3;

the lithium niobate wafer comprises a lithium niobate wafer main body and an annealing repair layer positioned on the lithium niobate wafer main body.