Wafer middle alignment optical system applied to wafer bonding machine

Abstract

The invention relates to the field of optics, and particularly discloses a wafer middle alignment optical system applied to a wafer bonding machine. According to the invention, two light transmission lines composed of the tube mirror module, the semi-transparent and semi-reflective mirror, the lighting module, the reflecting prism and the objective lens module are arranged on the two sides of the prism gluing group respectively, the lighting module sends light to the semi-transparent and semi-reflective mirror, and the light is reflected and transmitted to the reflecting prism; light emitted by the lens module enters the prism gluing group through the reflecting prism and the objective lens module in sequence and is reflected to the wafer through the prism gluing group, the wafer reflects the light, the reflected light is transmitted to the tube lens module through the prism gluing group, the objective lens module, the reflecting prism and the semi-transparent and semi-reflecting mirror in sequence, and the light emitted by the objective lens module is converged and imaged on the camera through the tube lens module. The wafers are aligned according to the image of the camera, the whole device is arranged in a flat mode and arranged between the two wafers, more space can be reserved for the wafers for attaching and approaching, the distance between the two wafers is shortened, and then the wafer attaching precision is improved.

Description

Technical Field

[0001] The invention belongs to the field of optical technology, and in particular relates to a wafer middle alignment optical system applied to a wafer bonding machine. Background Art

[0002] With the rapid development of the consumer electronics industry, the importance of semiconductor manufacturing has gradually become prominent. Various semiconductor manufacturing technologies are developing in the direction of high precision, high efficiency and low cost, and the alignment technology used in wafer bonding as an important part of semiconductor manufacturing technology is no exception.

[0003] Wafer bonding technology refers to the process of tightly bonding two mirror-polished homogeneous or heterogeneous wafers through chemical and physical effects. After the wafers are bonded, the atoms on the interface react under the action of external forces to form covalent bonds to form a whole, and the bonding interface reaches a specific bonding strength. In order to accurately close the upper and lower structures together, the upper and lower wafers are marked with alignment marks. Wafer bonding requires a microscopic alignment system to identify the alignment marks on the chip and substrate to achieve precise alignment. There is an alignment method in the bonding alignment module of the wafer bonder, namely, wafer center alignment. When other methods do not meet the alignment requirements, wafer center alignment can be used, that is, the upper and lower objective lenses observe at the same time. Due to the influence of the objective lens's own structural size and long working distance, this structure will inevitably lead to a large spacing between the two wafers, affecting the upper and lower wafer bonding accuracy. In addition, this alignment method needs to minimize the spacing between the two wafers as much as possible to reduce the Z-direction, i.e., longitudinal bonding error.

[0004] However, the Z-direction spacing of the wafers that need to be aligned is large, and there will be a large error in the Z-direction bonding of the wafers after alignment, which greatly reduces the accuracy of wafer bonding. It is necessary to reduce the Z-direction size and working distance of the alignment optical system as much as possible. Therefore, it is necessary to re-set an alignment observation system to replace the traditional objective lens for wafer alignment observation. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide an intermediate wafer alignment optical system for use in a wafer bonding machine to solve the problem that the traditional objective lens observation method causes a large distance between two wafers to be aligned, thereby resulting in poor wafer bonding accuracy.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] An optical system for wafer mid-alignment used in a wafer bonder, comprising:

[0008] A tube lens module, used for receiving incident light;

[0009] A semi-transparent and semi-reflective mirror, arranged obliquely on one side of the tube mirror module;

[0010] An illumination module, disposed on one side of the semi-transparent and semi-reflective mirror, for providing incident light to the semi-transparent and semi-reflective mirror;

[0011] A reflecting prism, the reflecting prism is arranged on one side of the semi-transparent and semi-reflective mirror, and is used to reflect incident light;

[0012] An objective lens module, arranged on one side of the reflecting prism and used for transmitting incident light;

[0013] A prism bonding group is arranged on one side of the objective lens module, and is used to reflect incident light to the wafer. The prism bonding group is formed by superimposing and combining two triangular prisms, and the inclination direction of the triangular prisms is arranged longitudinally;

[0014] The tube lens module, the semi-transparent and semi-reflective mirror, the lighting module, the reflecting prism and the objective lens module form a light transmission line, and one of the light transmission lines is respectively arranged on both sides of the prism bonding group.

[0015] Preferably, the prism bonding group is arranged between two wafers to be aligned.

[0016] Preferably, the optical axis of the tube lens module and the optical axis of the objective lens module are in the same plane and are perpendicular to each other.

[0017] Preferably, the lighting module is located on one side of the light transmission line of the tube lens module, the semi-transparent and semi-reflective mirror and the reflecting prism.

[0018] Preferably, the angles between the bonding surfaces of the prism bonding group and the two wafer surfaces are both 45°.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention sets two light transmission lines consisting of a tube lens module, a semi-transparent and semi-reflective mirror, an illumination module, a reflecting prism and an objective lens module, and sets them on both sides of a prism bonding group respectively. The illumination module sends light to the semi-transparent and semi-reflective mirror, and the light is reflected and transmitted to the reflecting prism, and is sequentially incident on the prism bonding group via the reflecting prism and the objective lens module, and is reflected on the wafer via the prism bonding group. At this time, the wafer reflects the incident light, and the reflected incident light is sequentially transmitted to the tube lens module via the prism bonding group, the objective lens module, the reflecting prism and the semi-transparent and semi-reflective mirror. The tube lens module converges the light emitted by the objective lens module to form an image on a target surface of a camera, and an operator aligns the wafer through the image on the target surface of the camera. The whole device is flatly arranged and placed between two wafers, so that more space can be reserved for the wafers to be bonded and brought close together, thereby reducing the distance between the two wafers and improving the wafer bonding accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] In the figure: 1. tube lens module; 2. semi-transparent and semi-reflective mirror; 3. lighting module; 4. reflecting prism; 5. objective lens module; 6. prism gluing group. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example:

[0025] See also Figure 1 -, a wafer mid-alignment optical system applied to a wafer bonding machine, comprising:

[0026] Tube lens module 1, used for receiving incident light;

[0027] A semi-transparent and semi-reflective mirror 2 is arranged obliquely on one side of the tube mirror module 1;

[0028] An illumination module 3, disposed on one side of the semi-transparent and semi-reflective mirror 2, and used for providing incident light to the semi-transparent and semi-reflective mirror 2;

[0029] A reflecting prism 4, which is arranged on one side of the semi-transparent and semi-reflective mirror 2 and is used to reflect incident light;

[0030] An objective lens module 5 is arranged on one side of the reflecting prism 4 and is used to transmit incident light;

[0031] A prism bonding group 6 is arranged on one side of the objective lens module 5, and is used to reflect incident light to the wafer. The prism bonding group 6 is formed by superimposing and combining two triangular prisms, and the inclination direction of the triangular prisms is arranged longitudinally;

[0032] The tube lens module 1, the semi-transparent and semi-reflective mirror 2, the lighting module 3, the reflecting prism 4 and the objective lens module 5 form a light transmission line, and one of the light transmission lines is respectively arranged on both sides of the prism bonding group 6.

[0033] By setting up two light transmission lines consisting of a tube lens module 1, a semi-transparent and semi-reflective mirror 2, an illumination module 3, a reflecting prism 4 and an objective lens module 5, and arranging them on both sides of a prism bonding group 6 respectively, the illumination module 3 sends light to the semi-transparent and semi-reflective mirror 2, the light is reflected and transmitted to the reflecting prism 4, and is sequentially incident on the prism bonding group 6 via the reflecting prism 4 and the objective lens module 5, and is reflected onto the wafer via the prism bonding group 6. At this time, the wafer reflects the incident light, and the reflected incident light is sequentially transmitted to the tube lens module 1 via the prism bonding group 6, the objective lens module 5, the reflecting prism 4 and the semi-transparent and semi-reflective mirror 2, and the tube lens module 1 converges the light emitted by the objective lens module 5 to form an image on a target surface of a camera, and an operator aligns the wafer through the image on the target surface of the camera. The entire device is flattened and placed between two wafers, which can reserve more space for the wafers to fit together and close together, thereby reducing the distance between the two wafers and improving the wafer bonding accuracy.

[0034] The prism gluing group 6 is disposed between two wafers to be aligned, and the prism gluing group 6 can be aligned with the alignment marks on the wafers to determine the position of the wafers.

[0035] The optical axis of the tube lens module 1 and the optical axis of the objective lens module 5 are in the same plane and perpendicular to each other, which facilitates accurate transmission of light.

[0036] In order to prevent the lighting module 3 from blocking the light transmission, the lighting module 3 is located on one side of the light transmission line of the tube lens module 1 , the semi-transparent and semi-reflective mirror 2 and the reflecting prism 4 .

[0037] The angles between the bonding surface of the prism bonding group 6 and the two wafer surfaces are both 45°, so that the light reflected by the wafer can accurately enter the prism bonding group 6 again for reflection.

[0038] During use, the entire system is placed between two wafers to be bonded, and the lighting module 3 images the light-emitting surface of the light source to the aperture of the objective lens module 5 to ensure that the light in the objective lens module 5 is uniform and sufficient. The image light on the wafer surface is reflected by the prism bonding group 6 and transmitted to the objective lens module 5. The image of the objective lens module 5 is reflected by the reflecting prism 4 and transmitted to the semi-transparent and semi-reflective mirror 2, and then transmitted to the tube lens module 1 via the semi-transparent and semi-reflective mirror 2. The tube lens module 1 converges the light emitted by the objective lens module 5 and images it on the target surface of the camera. The operator determines the position of the wafer through the image of the camera and adjusts the alignment accuracy of the wafer position lifter. Moreover, the distance between the two wafers is small enough to shorten the bonding stroke of the wafers and further improve the bonding accuracy of the wafers.

[0039] The standard parts used in the present invention can all be purchased from the market, and the special-shaped parts can be customized according to the description and the drawings. The specific connection methods of each part adopt conventional means such as mature bolts, rivets, welding, etc. in the prior art. The machinery, parts and equipment all adopt conventional models in the prior art, and the circuit connection adopts the conventional connection method in the prior art, which will not be described in detail here. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0040] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0042] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0043] In the drawings of the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

Claims

1. A wafer mid-alignment optical system for a wafer bonding machine, characterized in that: include: A tube lens module (1), used for receiving incident light; A semi-transparent and semi-reflective mirror (2) is arranged obliquely on one side of the tube mirror module (1); An illumination module (3) is arranged on one side of the semi-transparent and semi-reflective mirror (2) and is used to provide incident light for the semi-transparent and semi-reflective mirror (2); A reflecting prism (4), the reflecting prism (4) being arranged on one side of the semi-transparent and semi-reflective mirror (2) and being used for reflecting incident light; An objective lens module (5) is arranged on one side of the reflecting prism (4) and is used to transmit incident light; A prism bonding group (6) is arranged on one side of the objective lens module (5) and is used to reflect incident light to the wafer, and the prism bonding group (6) is formed by superimposing and combining two triangular prisms, and the inclination direction of the triangular prisms is arranged longitudinally; The tube lens module (1), the semi-transparent and semi-reflective mirror (2), the lighting module (3), the reflecting prism (4) and the objective lens module (5) form a light transmission line, and one of the light transmission lines is respectively arranged on both sides of the prism bonding group (6).

2. The wafer mid-alignment optical system for wafer bonding machine according to claim 1, characterized in that: The prism bonding group (6) is arranged between two wafers to be aligned.

3. The wafer mid-alignment optical system for wafer bonding machine according to claim 1, characterized in that: The optical axis of the tube lens module (1) and the optical axis of the objective lens module (5) are located in the same plane and are perpendicular to each other.

4. The wafer mid-alignment optical system for wafer bonding machine according to claim 1, characterized in that: The lighting module (3) is located on one side of the light transmission line of the tube lens module (1), the semi-transparent and semi-reflective mirror (2) and the reflecting prism (4).

5. The wafer mid-alignment optical system for wafer bonding machine according to claim 2, characterized in that: The included angles between the bonding surface of the prism bonding group (6) and the two wafer surfaces are both 45°.

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