Wafer bonding gap air elimination process

Abstract

The application relates to the field of wafer processing technology and specifically relates to a wafer bonding gap air elimination process, which comprises the following steps: adsorbing and fixing a glass carrier disk bonded with a wafer on a rotating table, adjusting a first nozzle to be aligned with the front surface of the wafer; arranging a baffle with a notch at the edge of the wafer to wrap the polyimide, and adjusting a second nozzle to be aligned with the notch; first, opening the first nozzle to continuously spray pure water to the front surface of the wafer, forming a protective water layer on the wafer to immerse the polyimide; then, opening the second nozzle to continuously spray NMP solvent to the notch, forming an etching area, and etching and removing the polyimide in the etching area by the NMP solvent, so that the etching area is communicated with the bonding gap; after the etching and removing treatment of the wafer, vacuum technology is carried out, and subsequent processes of the wafer are carried out. According to the air elimination process, NMP solvent is sprayed on the protective water layer, the polyimide is etched and removed, and the air in the bonding gap is removed.

Description

Technical Field

[0001] This invention relates to the field of wafer fabrication technology, specifically a process for eliminating air gaps in wafer bonding. Background Technology

[0002] Wafer bonding refers to the process of connecting two or more substrates or wafers to each other through a series of physical and chemical processes.

[0003] The prior art discloses an invention with application number CN202111640258.4 entitled: A process for SiC wafer processing using a carrier disk, wherein a polyimide coating is applied to the front side of the wafer to form a sealing layer, and after exposure, development and etching of the polyimide, the polyimide on the outer ring of the wafer is left to bond and fix the wafer.

[0004] However, during bonding, there is a gap between the back of the wafer and the glass carrier. Air exists in the bonding gap. During wafer vacuum processes, high-temperature processes, etc., the air pushes the wafer upward. The thickness of SiC wafers produced is generally between 100-200μm. The upward force exerted by the air on the wafer can cause the wafer to break, resulting in large losses and a high defect rate. Summary of the Invention

[0005] The purpose of this invention is to provide a wafer bonding gap air elimination process to solve the problems in the prior art.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A wafer bonding gap air elimination process, the air elimination process comprising the following steps:

[0008] S1. The glass carrier disk with the bonded wafer is adsorbed and fixed on the rotating stage, and the first nozzle is adjusted to be aligned with the front side of the wafer.

[0009] S2. Place the baffle with the notch at the edge of the wafer to wrap the polyimide, and adjust the second nozzle to align with the notch.

[0010] S3. First, open the first nozzle and continuously spray pure water onto the front side of the wafer to form a protective water layer on the wafer that is immersed in polyimide.

[0011] S4. Open the second nozzle and continuously spray NMP solvent into the notch to form an etched area. The NMP solvent etches and removes the polyimide in the etched area, making the etched area connected to the bonding gap.

[0012] S5. After etching, the wafer is subjected to a vacuum process to extract the air from the bonding gaps in the etched area before proceeding with subsequent wafer processing.

[0013] Further, the glass carrier plate is replaced by a glass carrier board.

[0014] Further, the S1 includes that the edge of the wafer is provided with polyimide, and the wafer back is bonded to the glass carrier plate through the polyimide.

[0015] Further, the heating temperature of the polyimide curing is not more than 300 DEG C.

[0016] Further, the baffle in the S2 is provided with at least two notches.

[0017] Further, the protective water layer in the S3 forms a water curtain on the baffle after overflowing the baffle.

[0018] Further, the second nozzle in the S4 sprays NMP solvent into the notch to flush away the pure water in the notch to form an etching area.

[0019] Further, the rotating table is provided with a first nozzle, and the rotating table is provided with at least two second nozzles in a slope manner, the first nozzle is connected to a pure water supply device, and the second nozzle is connected to an NMP solvent supply device.

[0020] The beneficial effects of the present application are as follows:

[0021] 1. In the air elimination process, the rotating table is used for adsorbing and fixing the glass carrier plate, the baffle is attached to the polyimide at the edge, pure water is continuously sprayed to form a protective water layer and a water curtain, the polyimide is fully protected, at least two notches are formed on the baffle, NMP solvent is sprayed into the notches, and the polyimide in the notches is etched and removed.

[0022] 2. In the air elimination process, after the polyimide is etched and removed, an etching area in communication with the bonding gap is formed, air in the bonding gap can be directly removed by vacuumizing, hidden dangers in subsequent processing are eliminated, the processing safety of the wafer is ensured, the defective rate is reduced, and the production cost is reduced.

[0023] 3. In the air elimination process, the temperature of the bonded and cured polyimide cannot exceed 300 DEG C, the NMP solvent can be directly etched and removed, and the elimination is convenient. BRIEF DESCRIPTION OF DRAWINGS

[0024] The present application will be further described below with reference to the drawings.

[0025] Figure 1 It is a schematic diagram of the wafer bonding structure of the present application.

[0026] Figure 2 It is a schematic diagram of the glass carrier plate connected to the baffle structure of the present application.

[0027] Figure 3 It is a top view of the rotating table of the present application.

[0028] Figure 4 is a front view of the rotating table of the present application.

[0029] Reference signs are as follows:

[0030] 1-glass carrier, 2-wafer, 3-polyimide, 4-bonding gap, 5-baffle, 6-first nozzle, 7-second nozzle, 8-etching area, 9-rotating table. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0032] A wafer bonding gap air elimination process, as shown in Figure 1 , the wafer 2 is arranged on the glass carrier 1, the glass carrier 1 can also be replaced by a glass carrier plate, the edge of the wafer 2 is fixedly provided with the polyimide 3, in the edge sealing operation of the polyimide 3, the heating temperature is not more than 300 DEG C, the wafer 2 is bonded on the glass carrier 1 by using the polyimide 3, at this time, the bonding gap 4 exists between the wafer 2 and the glass carrier 1.

[0033] The bonding gap 4 is filled with air, the subsequent high-temperature tempering process and vacuum process of the wafer 2 will cause the air in the bonding gap 4 to expand, and the air expansion will extrude the wafer 2, since the wafer 2 is thin, there is a possibility that the air will break the wafer 2.

[0034] As shown in Figure 2 , Figure 3 , Figure 4 , the air elimination process comprises the following steps:

[0035] S1, the glass carrier 1 is placed on the rotating table 9, the rotating table 9 is fixedly arranged above the glass carrier 1 by adsorption, and the first nozzle 6 is aligned with the center of the wafer 2 on the glass carrier 1.

[0036] S2, the baffle 5 is arranged at the edge of the wafer 2, and the polyimide 3 is wrapped, at least two notches are formed on the baffle 5, the second nozzle 7 is arranged on the rotating table 9, and the second nozzle 7 is aligned with the notches.

[0037] S3, the first nozzle 6 is opened, and pure water is continuously sprayed onto the wafer 2 to form a protective water layer on the wafer 2, the protective water layer overflows the baffle 5 to form a water curtain on the baffle 5, and the polyimide 3 is immersed to protect the polyimide 3.

[0038] S4, the second nozzle 7 is arranged obliquely to continuously spray NMP solvent into the gap of the baffle 5, the NMP solvent is sprayed into the gap, the pure water in the gap is flushed away to form an etching area 8, the polyimide 3 in the etching area 8 is dissolved, the polyimide 3 in the gap is removed, and the water curtain protects the polyimide 3 outside the gap.

[0039] S5, the etching area 8 is communicated with the bonding gap 4, a vacuum process is performed to extract the air in the bonding gap 4, and then subsequent processes of the wafer 2 are performed.

[0040] In this embodiment, the NMP solvent is N-methyl pyrrolidone.

[0041] In this embodiment, the working principle of the wafer bonding gap air elimination process is as follows:

[0042] The back surface of the wafer 2 is placed on the glass carrier 1, the wafer 2 is coated with the polyimide 3, the polyimide 3 in the middle of the front surface of the wafer 2 is removed by exposure and development, the polyimide 3 at the edge is left to bond and fix the wafer 2 to the glass carrier 1, then the glass carrier 1 is placed on the rotating table 9, the glass carrier 1 is fixed by adsorption, the baffle 5 with a gap is installed at the edge of the wafer 2 and is attached to the side of the polyimide 3, the first nozzle 6 is aligned with the center of the wafer 2 to spray pure water, a water curtain is formed on the baffle 5, and a protective water layer is formed on the wafer 2.

[0043] The second nozzle 7 is used to spray NMP solvent towards the gap, the pure water in the gap is discharged, the polyimide 3 in the gap is etched and thinned to form the etching area 8, the etching area 8 is communicated with the bonding gap 4, the air in the bonding gap 4 is discharged through a vacuum process, and then subsequent processing of the wafer 2 is performed, there is no air in the bonding gap 4, and the wafer 2 is heated and subjected to a vacuum process, so that the wafer 2 is not broken due to air expansion in the bonding gap 4.

[0044] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0045] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A wafer bonding gap air elimination process, characterized by, The air elimination process comprises the following steps: S1, the glass carrier (1) bonded with the wafer (2) is adsorbed and fixed on the rotating table (9), and the first nozzle (6) is adjusted to be aligned with the front surface of the wafer (2); S2, the baffle (5) with notches is arranged at the edge of the wafer (2) to wrap the polyimide (3), and the second nozzle (7) is adjusted to be aligned with the notches; S3, first open the first nozzle (6), continuously spray pure water to the front surface of the wafer (2), and form a protective water layer on the wafer (2) to immerse the polyimide (3); S4, then open the second nozzle (7), continuously spray NMP solvent to the notches to form an etching area (8), and the NMP solvent etches and removes the polyimide (3) in the etching area (8) to make the etching area (8) communicate with the bonding gap (4); S5, after the etching and removal of the wafer (2), the vacuum process is carried out to extract the air in the bonding gap (4) from the etching area (8), and then the subsequent process of the wafer (2) is carried out; The baffle (5) in S2 is provided with at least two notches; The protective water layer in S3 flows over the baffle (5) to form a water curtain on the baffle (5); The second nozzle (7) in S4 sprays NMP solvent into the notches to flush away the pure water in the notches to form the etching area (8); The rotating table (9) is provided with the first nozzle (6), and the rotating table (9) is provided with at least two second nozzles (7) obliquely, the first nozzle (6) is connected with a pure water supply device, and the second nozzle (7) is connected with an NMP solvent supply device.

2. A wafer bonding gap air elimination process as claimed in claim 1, wherein, The glass carrier (1) is replaced by a glass carrier plate.

3. A wafer bonding gap air elimination process as claimed in claim 1, wherein, In S1, the edge of the wafer (2) is solidified with the polyimide (3), and the wafer (2) is bonded on the glass carrier (1) through the polyimide (3).

4. A wafer bonding gap air elimination process as claimed in claim 3, wherein, The solidification heating temperature of the polyimide (3) is not more than 300 DEG C.

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