阅读说明：本技术 键合设备及键合过程的监控方法 (Bonding equipment and monitoring method of bonding process ) 是由 曹瑞霞 于 2021-11-16 设计创作，主要内容包括：本发明提供了一种键合设备,包括承载台、下卡盘、上卡盘、顶针、多组光感传感器和控制单元；所述承载台用于承载所述下卡盘,所述下卡盘用于固定第一晶圆,所述上卡盘用于固定第二晶圆,所述顶针可穿过所述上卡盘以下压所述第二晶圆；所述多组光感传感器位于所述承载台上,每个所述光感传感器的高度高于所述第一晶圆预定高度,每个光感传感器包括光发射单元和光接收单元,所述光发射单元与所述光接收单元相对设置；所述控制单元根据所述光接收单元获得的光信号判断第二晶圆的下压过程中的形变量是否正常。本发明解决了晶圆向下移动不顺畅或者移动偏心的问题,提高了晶圆键合的质量。(The invention provides bonding equipment which comprises a bearing table, a lower chuck, an upper chuck, a thimble, a plurality of groups of light-sensitive sensors and a control unit, wherein the bearing table is provided with a plurality of groups of light-sensitive sensors; the bearing table is used for bearing the lower chuck, the lower chuck is used for fixing a first wafer, the upper chuck is used for fixing a second wafer, and the ejector pins can penetrate through the upper chuck to press the second wafer; the multiple groups of light-sensitive sensors are positioned on the bearing table, the height of each light-sensitive sensor is higher than the preset height of the first wafer, each light-sensitive sensor comprises a light emitting unit and a light receiving unit, and the light emitting units and the light receiving units are arranged oppositely; and the control unit judges whether the deformation amount of the second wafer in the pressing process is normal or not according to the optical signal obtained by the optical receiving unit. The invention solves the problem that the wafer does not move smoothly downwards or moves eccentrically, and improves the bonding quality of the wafer.)

1. A bonding device is characterized by comprising a bearing platform, a lower chuck, an upper chuck, a thimble, a plurality of groups of light-sensitive sensors and a control unit;

the bearing table is used for bearing the lower chuck, the lower chuck is used for fixing a first wafer, the upper chuck is used for fixing a second wafer, and the ejector pins can penetrate through the upper chuck to press the second wafer;

the multiple groups of light-sensitive sensors are positioned on the bearing table, the height of each light-sensitive sensor is higher than the preset height of the first wafer, each light-sensitive sensor comprises a light emitting unit and a light receiving unit, and the light emitting units and the light receiving units are arranged oppositely; the light emitting unit of the light sensor is used for emitting light parallel to the surface of the first wafer, and the light receiving unit is used for receiving the light emitted by the light emitting unit;

and the control unit judges whether the deformation amount of the second wafer in the pressing process is normal or not according to the optical signal obtained by the optical receiving unit.

2. The bonding apparatus of claim 1, wherein the image received by the light receiving unit includes a blocking area and a photosensitive area, and the step of the control unit determining whether the amount of deformation during the pressing down of the second wafer is normal according to the optical signal obtained by the light receiving unit comprises:

if the area of the blocking area is between the first preset value and the second preset value and the blocking area is positioned on two symmetrical sides of the thimble, judging that the deformation amount of the second wafer in the pressing process is normal;

if the area of the blocking area is smaller than a first preset value, judging that the thimble is not pressed in place in the pressing process of the second wafer, and the deformation of the second wafer does not meet the preset requirement;

and if the area of the blocking area is larger than a second preset value and deviates from the center of the thimble, judging that the thimble is pressed down to cause the irregular deformation of the second wafer.

3. The bonding apparatus of claim 1, wherein the plurality of sets of photo sensors are uniformly disposed around the second wafer.

4. The bonding apparatus of claim 1, wherein the predetermined height is 50 μ ι η to 500 μ ι η from the first wafer.

5. The bonding apparatus of claim 1, wherein the light emitting unit is a short wave transmitter and the light receiving unit is a short wave sensor.

6. The bonding apparatus of claim 1, wherein the control unit is connected to the ejector pin and configured to control the ejector pin to press the second wafer.

7. The bonding apparatus of claim 1, wherein the upper chuck and the lower chuck each include a loading pin having a vacuum hole disposed thereon.

8. The bonding apparatus of claim 7, wherein the upper and lower chucks further comprise a loading hole, and the loading pin is located in the loading hole and is movable in the loading hole.

9. The bonding apparatus of claim 1, wherein the control unit adjusts the position of the ejector pin if the amount of deformation during the pressing of the second wafer is abnormal.

10. A method of monitoring a bonding process using the bonding apparatus according to any one of claims 1 to 9, comprising:

fixing a first wafer by using a lower chuck, fixing a second wafer by using an upper chuck, and applying bonding pressure to the second wafer through a thimble;

a light emitting unit of the light sensor emits light parallel to the surface of the first wafer, and a light receiving unit of the light sensor receives the light emitted by the light emitting unit;

and the control unit judges whether the deformation amount of the second wafer in the pressing process is normal or not according to the optical signal obtained by the optical receiving unit.

11. The method for monitoring the bonding process according to claim 10, wherein the image received by the light receiving unit includes a blocking area and a photosensitive area, and the step of the control unit determining whether the deformation amount during the pressing down of the second wafer is normal according to the optical signal obtained by the light receiving unit comprises:

if the area of the blocking area is between the first preset value and the second preset value and the blocking area is positioned on two symmetrical sides of the thimble, judging that the deformation amount of the second wafer in the pressing process is normal;

if the area of the blocking area is smaller than a first preset value, judging that the thimble is not pressed in place in the pressing process of the second wafer, and the deformation of the second wafer does not meet the preset requirement;

and if the area of the blocking area is larger than a second preset value and deviates from the center of the thimble, judging that the thimble is pressed down to cause the irregular deformation of the second wafer.

Technical Field

The invention relates to the technical field of semiconductor devices, in particular to bonding equipment and a monitoring method of a bonding process.

Background

With the continuous development of semiconductor technology, wafer bonding technology is widely used, and the wafer bonding technology is to bond two wafers together by bonding technology to realize the vertical interconnection of the two wafers.

In the three-dimensional integration process, wafer bonding is a key core process in the whole process flow, and bonding force is a key index in the bonding process, and determines defects at the edge of a product, the yield of the product and the reliability of the product after the product.

The current wafer bonding machine can effectively detect the alignment process before wafer bonding, but the wafer bonding process in the key process cannot be effectively monitored.

The wafer bonding step will affect the wafer alignment accuracy, wafer bonding strength, and other indicators, further affecting the reliability indicators of the subsequent products. In the wafer bonding step, when the wafer moves downward unsmoothly or moves eccentrically, the wafer bonding can cause two wafer micro-sliding pieces or wafer deformity, thereby affecting the wafer bonding quality.

Disclosure of Invention

The invention aims to provide bonding equipment and a monitoring method of a bonding process, which are used for solving the problem that in the wafer bonding step, when a wafer moves downwards unsmoothly or moves eccentrically, wafer bonding can cause micro-sliding sheets of two wafers or wafer deformity, and the quality of wafer bonding is influenced.

To solve the above technical problem, the present invention provides a bonding apparatus, comprising:

the device comprises a bearing table, a lower chuck, an upper chuck, a thimble, a plurality of groups of light-sensitive sensors and a control unit;

the bearing table is used for bearing the lower chuck, the lower chuck is used for fixing a first wafer, the upper chuck is used for fixing a second wafer, and the ejector pins can penetrate through the upper chuck to press the second wafer;

the multiple groups of light-sensitive sensors are positioned on the bearing table, the height of each light-sensitive sensor is higher than the preset height of the first wafer, each light-sensitive sensor comprises a light emitting unit and a light receiving unit, and the light emitting units and the light receiving units are arranged oppositely; the light emitting unit of the light sensor is used for emitting light parallel to the surface of the first wafer, and the light receiving unit is used for receiving the light emitted by the light emitting unit;

and the control unit judges whether the deformation amount of the second wafer in the pressing process is normal or not according to the optical signal obtained by the optical receiving unit.

Optionally, the step of determining, by the control unit, whether the deformation amount of the second wafer in the pressing process is normal according to the optical signal obtained by the light receiving unit includes:

if the area of the blocking area is between the first preset value and the second preset value and the blocking area is positioned on two symmetrical sides of the thimble, judging that the deformation amount of the second wafer in the pressing process is normal;

if the area of the blocking area is smaller than a first preset value, judging that the thimble is not pressed in place in the pressing process of the second wafer, and the deformation of the second wafer does not meet the preset requirement;

and if the area of the blocking area is larger than a second preset value and deviates from the center of the thimble, judging that the thimble is pressed down to cause the irregular deformation of the second wafer.

Optionally, the plurality of groups of light-sensitive sensors are uniformly arranged around the second wafer.

Optionally, the predetermined height is 50 μm to 500 μm from the first wafer.

Optionally, the light emitting unit is a short wave emitter, and the light receiving unit is a short wave sensor.

Optionally, the control unit is connected to the ejector pin and configured to control the ejector pin to press down the second wafer.

Optionally, the upper chuck and the lower chuck include loading needles, and the loading needles are provided with vacuum holes.

Optionally, the upper chuck and the lower chuck further include: a loading hole in which the loading needle is located and movable.

Optionally, if the deformation amount of the second wafer in the pressing process is abnormal, the control unit adjusts the position of the thimble.

Based on the same inventive concept, the present invention further provides a method for monitoring a bonding process, which uses any one of the above bonding apparatuses for monitoring, and comprises:

fixing a first wafer by using a lower chuck, fixing a second wafer by using an upper chuck, and applying bonding pressure to the second wafer through a thimble;

a light emitting unit of the light sensor emits light parallel to the surface of the first wafer, and a light receiving unit of the light sensor receives the light emitted by the light emitting unit;

and the control unit judges whether the deformation amount of the second wafer in the pressing process is normal or not according to the optical signal obtained by the optical receiving unit.

Optionally, the step that the image received by the light receiving unit includes a blocking area and a photosensitive area, and the step that the control unit determines whether the deformation amount of the second wafer in the pressing process is normal according to the optical signal obtained by the light receiving unit includes:

if the area of the blocking area is between the first preset value and the second preset value and the blocking area is positioned on two symmetrical sides of the thimble, judging that the deformation amount of the second wafer in the pressing process is normal;

if the area of the blocking area is smaller than a first preset value, judging that the thimble is not pressed in place in the pressing process of the second wafer, and the deformation of the second wafer does not meet the preset requirement;

and if the area of the blocking area is larger than a second preset value and deviates from the center of the thimble, judging that the thimble is pressed down to cause the irregular deformation of the second wafer.

Compared with the prior art, the invention has the beneficial effects that:

in the bonding equipment and the monitoring method of the bonding process, a plurality of light-sensitive sensors are arranged on a bearing table around the second wafer, the height of each light-sensitive sensor is higher than the preset height of the first wafer, each light-sensitive sensor comprises a light emitting unit and a light receiving unit, and the light emitting unit and the light receiving unit are arranged oppositely; the light emitting unit of the light sensor is used for emitting light parallel to the surface of the first wafer, and the light receiving unit is used for receiving the light emitted by the light emitting unit; the control unit judges whether the deformation amount of the second wafer in the process of pressing down is normal or not according to the optical signal obtained by the optical receiving unit, and the deformation amount of the wafer in the process of moving downwards is normal or not in the step of wafer bonding by monitoring whether the deformation amount of the wafer in the process of moving downwards is normal or not, so that the problem that the wafer moves downwards unsmoothly or moves eccentrically in the step of wafer bonding is found and adjusted, and the quality of wafer bonding is improved.

Drawings

FIG. 1 is a schematic diagram illustrating a prior art bonding process without a thimble pressed in place;

FIG. 2 is a schematic diagram illustrating the eccentricity of the movement of the thimble during the bonding process in the prior art;

FIG. 3 is a schematic view of a bonding apparatus according to an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating a positional relationship between a chuck and a wafer in a bonding apparatus according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of the distribution of light sensors in a bonding apparatus according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of the optical path of a photo sensor in a bonding apparatus according to an embodiment of the present invention;

FIG. 7 is an image of a second wafer becoming normal during bonding according to an embodiment of the present invention;

FIG. 8 is an image of a second wafer deformation anomaly during bonding in accordance with an embodiment of the present invention;

FIG. 9 is an image of a second wafer changing to another anomaly during bonding according to an embodiment of the present invention;

FIG. 10 is a flow chart of a method for monitoring a bonding process according to an embodiment of the present invention;

in the figure, the position of the upper end of the main shaft,

10-a carrier table; 11-a first wafer; 12-a second wafer; 13-a thimble; 14 a-a light emitting unit; 14 b-a light receiving unit; 15-lower chuck; 16-upper chuck; 17-a photosensitive region; 18-barrier region.

Detailed Description

The present invention provides a bonding apparatus and a method for monitoring a bonding process, which are described in detail below with reference to the accompanying drawings and specific embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

The inventor researches and discovers that the bonding equipment can comprise an upper chuck and a lower chuck, wherein the lower chuck is used for adsorbing a first wafer 11, the lower chuck is used for adsorbing a second wafer 12, the middle part of the upper chuck is used for applying pressure to the second wafer 12 through a thimble 13 in the bonding process, the middle part of the second wafer 12 is close to and contacted with the first wafer 11, in the deformation process of the second wafer 12, a bonding wave moves from the center of the wafer to the edge, and then the adsorption vacuum of the upper wafer is released from the center to the edge in sequence, so that the second wafer and the first wafer are bonded under the action of the bonding wave. In the wafer bonding process, after the first wafer 11 and the second wafer 12 are aligned, the thimble 13 applies downward pressure on the surface of the second wafer, so that the two wafers are bonded together. As shown in fig. 1 and 2, during the process of applying the force to the second wafer 12 by the downward movement of the thimble 13, the deformation and the force of the second wafer 12 cannot be monitored, so that there is a risk as follows: first, the downward movement of the ejector pin 13 is not smooth enough, and the force is not applied to the surface of the second wafer 12 for a given time. Second, during the downward pushing of the ejector pin 13, the ejector pin 13 moves eccentrically, resulting in uneven force acting on the surface of the second wafer 12. If the thimble 13 moves down smoothly or moves eccentrically, the wafer bonding will cause two wafer micro-sliding pieces or wafer distortion. Thereby affecting wafer bonding quality.

Therefore, the core idea of the invention is that a plurality of light-sensitive sensors are arranged on a bearing table around a second wafer, the height of each light-sensitive sensor is higher than the preset height of the first wafer, each light-sensitive sensor comprises a light emitting unit and a light receiving unit, and the light emitting unit and the light receiving unit are arranged oppositely; the light emitting unit of the light sensor is used for emitting light parallel to the surface of the first wafer, and the light receiving unit is used for receiving the light emitted by the light emitting unit; and the control unit is connected with the light emitting unit and the light receiving unit, judges whether the deformation amount of the second wafer in the pressing process is normal or not according to the optical signal obtained by the light receiving unit, and monitors whether the deformation amount of the wafer in the downward moving process is normal or not in the wafer bonding step, so that the problem that the wafer does not move smoothly or moves eccentrically in the wafer bonding step is found and adjusted, and the wafer bonding quality is improved.

For a better understanding of the technical solutions and effects of the present application, specific embodiments will be described in detail below with reference to the accompanying drawings.

FIG. 3 is a schematic view of a bonding apparatus according to an embodiment of the present invention; FIG. 4 is a schematic diagram illustrating a positional relationship between a chuck and a wafer in a bonding apparatus according to an embodiment of the present invention; as shown in fig. 3 and 4, the present embodiment provides a bonding apparatus including: the device comprises a bearing table 10, a lower chuck 15, an upper chuck 16, a thimble 13, a plurality of groups of light-sensitive sensors and a control unit; the bearing table 10 is used for bearing the lower chuck 15, and the lower chuck 15 is used for fixing the first wafer 11; the upper chuck 16 is used for fixing the second wafer 12, the ejector pins 13 axially penetrate through the upper chuck 16, and the ejector pins 13 are used for pressing down the second wafer 12; a plurality of sets of light sensors, which are located on the supporting table 10, and the height of each light sensor is higher than the predetermined height of the first wafer, each set of light sensor includes a light emitting unit 14a and a light receiving unit 14b, and the light emitting unit 14a and the light receiving unit 14b are arranged oppositely; the light emitting unit 14a of the optical sensor is used for emitting light parallel to the surface of the first wafer, and the light receiving unit 14b of the optical sensor is used for receiving the light emitted by the light emitting unit 14 a; and a control unit (not shown in the figure) connected to the light emitting unit and the light receiving unit, wherein the control unit determines whether the deformation amount of the second wafer 12 in the pressing process is normal according to the optical signal obtained by the light receiving unit 14 b.

Further, if the amount of deformation during the pressing of the second wafer 12 is abnormal, the cause of the abnormal amount of deformation during the pressing of the second wafer 12 is searched for and adjusted. In the wafer bonding process, a number of factors causing the deformation abnormality in the pressing process of the second wafer 12 are, for example, the thimble 13 is not pressed in place in the pressing process of the second wafer 12, the deformation of the second wafer 12 does not meet the preset requirement, the thimble 13 is pressed to cause the irregular deformation of the second wafer 12, the second wafer 12 is not stressed from the central area of the surface of the second wafer, and if the deformation abnormality in the pressing process of the second wafer 12 is caused by the thimble, the control unit adjusts the position of the thimble 13 to ensure the deformation abnormality in the pressing process of the second wafer 12, so as to improve the wafer bonding quality.

FIG. 5 is a schematic diagram of the distribution of light sensors in a bonding apparatus according to an embodiment of the present invention; as shown in fig. 5, the plurality of sets of photo sensors are uniformly disposed on the carrier 10 around the second wafer, and the number of the plurality of sets of photo sensors in the transverse direction and the number of the plurality of sets of photo sensors in the longitudinal direction are, for example, 10 to 300 sets each. The light emitting unit 14a is disposed opposite to the light receiving unit 14 b. The light emitting unit 14a is, for example, a short wave transmitter, and the light receiving unit 14b is, for example, a short wave sensor.

As shown in fig. 1 and 6, the light emitted by the light emitting unit parallel to the surface of the first wafer is located between the first wafer 11 and the second wafer 12, and the height of the light sensor is higher than a predetermined height on the first wafer, for example, a height from the first wafer, for example, 50 μm to 500 μm.

FIG. 6 is a schematic diagram of the optical path of a photo sensor in a bonding apparatus according to an embodiment of the present invention; FIG. 7 is an image of a second wafer becoming normal during bonding according to an embodiment of the present invention; as shown in fig. 6 and 7, at a predetermined time during the pressing down of the second wafer, for example, the bonding process of the first wafer 11 and the second wafer 12 is a process of gradually contacting from the center to the periphery, the light emitted from the light emitting unit 14a is blocked by the deformed portion of the second wafer 12, and thus the image received by the light receiving unit 14b includes the blocking region 18 and the photosensitive region 17.

The control unit is connected with the ejector pin 13, and the control unit is used for controlling the ejector pin 13 to press down the second wafer 12. The upper chuck 16 and the lower chuck 15 further include loading pins (not shown), the loading pins are provided with vacuum holes, the upper chuck 16 adsorbs the second wafer 12 by vacuum suction, and the lower chuck 15 adsorbs the first wafer 11 by vacuum suction. The upper chuck 16 and the lower chuck 15 further include loading holes (not shown) in which the loading pins are located and movable.

Further, the step of the control unit determining whether the deformation amount of the second wafer 12 in the pressing process is normal according to the optical signal obtained by the optical receiving unit 14b includes:

as shown in fig. 7, if the area of the blocking area 18 is between the first predetermined value and the second predetermined value and the blocking area 18 is located at two symmetrical sides of the thimble 13, it is determined that the deformation amount of the second wafer 12 in the pressing process is normal. The first preset value and the second preset value of the area of the blocking area 18 are set according to the area of the second wafer, the first preset value is a lower limit value of the normal area of the blocking area, the second preset value is an upper limit value of the normal area of the blocking area, and the first preset value and the second preset value of the area of the blocking area 18 are determined by those skilled in the art according to actual situations, which is not limited in this embodiment.

FIG. 8 is an image of a second wafer deformation anomaly during bonding in accordance with an embodiment of the present invention; as shown in fig. 8, if the area of the blocking area 18 is smaller than a first preset value, it is determined that the thimble 13 is not pressed in place when the thimble is initially bonded in the pressing process of the second wafer 12, and the deformation of the second wafer does not meet the preset requirement;

FIG. 9 is an image of a second wafer changing to another anomaly during bonding according to an embodiment of the present invention; as shown in fig. 9, if the blocking area 18 is larger than the second predetermined value and deviates from the center of the thimble 13, it is determined that the thimble 13 is pressed down to cause the irregular deformation of the second wafer 12, that is, the second wafer 12 is not stressed from the surface center area of the second wafer.

FIG. 10 is a flow chart of a method for monitoring a bonding process according to an embodiment of the present invention; as shown in fig. 10, this embodiment further provides a method for monitoring a bonding process, including: the bonding equipment is used for monitoring, a first wafer and a second wafer are respectively adsorbed on the lower chuck and the upper chuck, and bonding waves are monitored after the ejector pins apply bonding pressure to the second wafer, wherein the monitoring method comprises the following steps:

step S10, fixing a first wafer by using a lower chuck, fixing a second wafer by using an upper chuck, and applying bonding pressure to the second wafer through a thimble;

step S20, the light emitting unit of the photo sensor emits light parallel to the surface of the first wafer, and the light receiving unit of the photo sensor receives the light emitted by the light emitting unit;

step S30, the control unit determines whether the deformation amount of the second wafer during the pressing process is normal according to the optical signal obtained by the optical receiving unit.

In step S10, at a predetermined time during the pressing of the second wafer, the light emitted from the light emitting unit 14a is blocked by the deformed portion of the second wafer 12, wherein the predetermined etching is, for example, the bonding half time, and the bonding process of the first wafer and the second wafer is a process of gradually contacting from the center to the periphery.

In step S30, the image received by the light receiving unit includes a blocking area and a photosensitive area, and the determining, by the control unit, whether the deformation amount of the second wafer during the pressing process is normal according to the optical signal obtained by the light receiving unit includes:

if the area of the blocking area is between the first preset value and the second preset value and the blocking area is positioned at two symmetrical sides of the thimble, the deformation of the second wafer in the pressing process is judged to be normal; the first preset value and the second preset value of the area of the blocking area 18 are set according to the area of the second wafer, the first preset value is a lower limit value of the normal area of the blocking area, the second preset value is an upper limit value of the normal area of the blocking area, and the first preset value and the second preset value of the area of the blocking area 18 are determined by those skilled in the art according to actual situations, which is not limited in this embodiment.

If the area of the blocking area is smaller than a first preset value, judging that the thimble is not pressed in place in the pressing process of the second wafer, and the deformation of the second wafer does not meet the preset requirement;

and if the blocking area is larger than a second preset value and deviates from the center of the thimble, judging that the thimble presses down to cause irregular deformation of the second wafer, wherein the second wafer does not start to be stressed from the surface center area of the second wafer.

In summary, in the bonding apparatus and the monitoring method of the bonding process provided by the present invention, a plurality of light sensors are disposed on a susceptor around a second wafer, the light sensors are higher than a predetermined height on the first wafer, each light sensor includes a light emitting unit and a light receiving unit, and the light emitting unit and the light receiving unit are disposed opposite to each other; the light emitting unit of the light sensor is used for emitting light parallel to the surface of the first wafer, and the light receiving unit is used for receiving the light emitted by the light emitting unit; and the control unit is connected with the light emitting unit and the light receiving unit, judges whether the deformation amount of the second wafer in the pressing process is normal or not according to the optical signal obtained by the light receiving unit, and monitors whether the deformation amount of the wafer in the downward moving process is normal or not in the wafer bonding step, so that the problem that the wafer does not move smoothly or moves eccentrically in the wafer bonding step is found and adjusted, and the wafer bonding quality is improved.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.