阅读说明：本技术 测量共晶键合对准偏差的测试结构 (Test structure for measuring eutectic bonding alignment deviation ) 是由 王俊杰 徐爱斌 于 2020-06-30 设计创作，主要内容包括：本发明公开了一种测量共晶键合对准偏差的测试结构,包括形成于第一硅晶圆的第一表面上的多个顶层硅条形以及形成于第二硅晶圆的第一表面上的第二键合材料块,在各顶层硅条形表面形成有第一键合材料层；各顶层硅条形作为共晶键合的对准偏差的刻度；第二键合材料块和第一测试衬垫连接；各顶层硅条形顶部的第一键合材料层都和对应的第二测试衬垫连接；进行对准偏差测量时,对第一和各第二测试衬垫的导通关系进行测量,导通时表示第二键合材料块和对应位置的顶层硅条形顶部的第一键合材料层键合,从而确定共晶键合的对准偏差。本发明能有效监控键合机台的对准精度。(The invention discloses a test structure for measuring eutectic bonding alignment deviation, which comprises a plurality of top silicon strips formed on the first surface of a first silicon wafer and a second bonding material block formed on the first surface of a second silicon wafer, wherein a first bonding material layer is formed on the surface of each top silicon strip; each top layer silicon strip is used as a scale of alignment deviation of eutectic bonding; the second block of bonding material is connected to the first test pad; the first bonding material layer at the top of each top silicon strip is connected with the corresponding second test pad; and when the alignment deviation is measured, measuring the conduction relation between the first test pad and each second test pad, and when the second test pad is conducted, indicating that the second bonding material block is bonded with the first bonding material layer at the top layer silicon strip-shaped top at the corresponding position, so that the alignment deviation of eutectic bonding is determined. The invention can effectively monitor the alignment precision of the bonding machine.)

1. The utility model provides a measure test structure of eutectic bonding alignment deviation which characterized in that: eutectic bonding is realized between the first silicon wafer and the second silicon wafer through a first bonding material layer formed on the first surface of the first silicon wafer and a second bonding material layer formed on the first surface of the second silicon wafer;

the test structure comprises a plurality of top silicon strips formed on the first surface of the first silicon wafer and a second bonding material block formed on the first surface of the second silicon wafer, wherein a first bonding material layer is formed on the surface of each top silicon strip;

each top layer silicon strip is used as a scale of alignment deviation of the eutectic bonding, and when the alignment deviation of the eutectic bonding occurs, the second bonding material block is bonded with the first bonding material layer at the top of the top layer silicon strip at the corresponding position;

the second block of bonding material is connected to the first test pad; the first bonding material layer on the top of each top silicon strip is connected with the corresponding second test pad;

and when the alignment deviation of the eutectic bonding is measured, measuring the conduction relation between the first test pad and each second test pad, and when the first test pad and the corresponding second test pad are conducted, indicating that the second bonding material block is bonded with the first bonding material layer at the top of the top silicon strip at the corresponding position, so as to determine the alignment deviation of the eutectic bonding.

2. The test structure for measuring eutectic bonding alignment deviations of claim 1, wherein: and the top silicon strips are in a parallel arrangement structure.

3. The test structure for measuring eutectic bond alignment bias of claim 2, wherein: and all the top silicon strips are arranged in parallel at equal intervals.

4. The test structure for measuring eutectic bond alignment bias of claim 3, wherein: and when eutectic bonding is performed between the first silicon wafer and the second silicon wafer, the second bonding material block is in eutectic bonding with more than one top layer silicon strip.

5. The test structure for measuring eutectic bonding alignment deviations of claim 1, wherein: a silicon-based MEMS motion sensor is formed on the first silicon wafer.

6. The test structure for measuring eutectic bond alignment bias of claim 5, wherein: the silicon-based MEMS motion sensor comprises a fixed electrode and a movable electrode, wherein a groove is arranged between the fixed electrode and the movable electrode at an interval.

7. The test structure for measuring eutectic bond alignment bias of claim 6, wherein: bonding the second surface of the first silicon wafer and a third silicon wafer;

the third silicon wafer is used as a sealing cover layer of the first silicon wafer.

8. The test structure for measuring eutectic bond alignment bias of claim 7, wherein: a cavity is formed on the third silicon wafer, the cavity corresponding in position to the movable electrode and providing a space for movement of the movable electrode.

9. The test structure for measuring eutectic bond alignment bias of claim 7, wherein: and the first silicon wafer and the third silicon wafer are bonded through silicon dioxide.

10. The test structure for measuring eutectic bonding alignment deviations of claim 1, wherein: and a buried oxide layer is isolated between each top layer silicon strip and the bottom layer silicon consisting of the first silicon wafer.

11. The test structure for measuring eutectic bond alignment bias of claim 5, wherein: and a CMOS integrated circuit is formed on the second silicon wafer and used for controlling the silicon-based MEMS motion sensor.

12. The test structure for measuring eutectic bonding alignment deviations of claim 1, wherein: forming a first search mark formed by patterning a first bonding material layer on the first surface of the first silicon wafer;

and a second search mark formed by patterning a second bonding material layer is formed on the first surface of the second silicon wafer.

13. The test structure for measuring eutectic bond alignment bias of claim 12, wherein: after the first silicon wafer and the second silicon wafer are in eutectic bonding, the first search mark and the second search mark are mutually aligned.

14. The test structure for measuring eutectic bond alignment bias of claim 5, wherein: the silicon-based MEMS motion sensor comprises a pressure sensor and an acceleration sensor.

15. The test structure for measuring eutectic bonding alignment deviations of any one of claims 1 to 14, wherein: the first bonding material includes germanium;

the second bonding material includes aluminum.

Technical Field

The present invention relates to semiconductor integrated circuits, and more particularly, to a test structure for measuring alignment deviation of eutectic bonding.

Background

Fig. 1 is a schematic diagram of a conventional silicon-based MEMS motion sensor, which includes 3 silicon wafers, i.e., a third silicon wafer 101, a first silicon wafer 102, and a second silicon wafer 103, bonded together.

The silicon-based MEMS motion sensor is formed on a first silicon wafer 102, a third silicon wafer 101 is used as a sealing layer of the first silicon wafer 102, a CMOS integrated circuit is formed on the first silicon wafer 103, and the silicon-based MEMS motion sensor is controlled through the CMOS integrated circuit.

A cavity 1 is formed in the third silicon wafer 101.

The silicon-based MEMS motion sensor comprises a fixed electrode and a movable electrode, wherein a groove 3 is arranged between the fixed electrode and the movable electrode. Wherein the cavity 1 corresponds in position to the movable electrode and provides space for the movement of the movable electrode. By changing the relative position of the fixed electrode and the movable electrode, the motion state can be checked, such as a pressure sensor, an acceleration sensor and the like, which is well applied to intelligent equipment such as smart phones, automobiles, medical treatment and the like.

The second silicon wafer 103 is formed with a CMOS integrated circuit, interlayer films 5 are formed on the top of the CMOS integrated circuit, metal layers are provided between the interlayer films 5, and the extraction of electrodes is realized by a top metal layer (TM) 6.

The third silicon wafer 101 and the first silicon wafer 102 are bonded together by an oxide layer, such as a silicon dioxide layer 2.

The second silicon wafer 103 and the first silicon wafer 102 are bonded to each other by eutectic bonding (eutecticebonding). If the third silicon wafer 101 is bonded to the second surface of the first silicon wafer 102, the second silicon wafer 103 is bonded to the first surface of the first silicon wafer 102, and the first surface and the second surface are front and back surfaces of the first silicon wafer 102.

In the eutectic bonding, the first bonding material layer 4 is a germanium (Ge) layer 4 formed on the second surface of the fixed electrode of the first silicon wafer 102, and the second bonding material layer 7 is composed of a metal layer formed on the surface of the top metal layer 6 and the interlayer film 5; the metal layer corresponding to the second bonding material layer 7 is a superposed layer of multiple metal layers, such as superposed layers of Ti, TiN and Al, or the metal layer of the second bonding material layer 7 is composed of a single layer of metal Al, and finally eutectic bonding of Al and Ge is realized. After eutectic bonding is performed between the first bonding material layer 4 and the second bonding material layer 7, the second silicon wafer 103 and the first silicon wafer 102 are bonded together, and electrical connection is achieved.

The silicon-based MEMS motion sensor connected with the CMOS integrated circuit Al-Ge eutectic bonding is also called a silicon-based CMOS-MEMS motion sensor such as a silicon-based CMOS-MEMS acceleration sensor, and the alignment precision of the microscopic patterns of the CMOS and the MEMS is very important and can directly influence the performance of the device. In the prior art, an alignment pattern only has search marks (searchmarks) of a bonding machine, namely, Alsearchmark and gemearchmark, but no mark for measuring the alignment (overlay) of Al searchmark and gemearchmark, namely, an alignment mark, cannot accurately judge alignment deviation, and cannot effectively monitor the alignment precision of a bonding machine.

As shown in fig. 2A, the diagram is a schematic diagram of a conventional gemearchmark, and the gemearchmark 201 includes graphs of two regions corresponding to dashed frames 201a and 201 b;

as shown in fig. 2B, which is a schematic diagram of an existing Alsearchmark, the Alsearchmark202 includes two area graphs corresponding to dashed boxes 202a and 202B;

as shown in fig. 2C, which is a registration diagram of fig. 2A and 2B, in the registration diagram 203, a region corresponding to a dashed box 203a is a graph formed by registering dashed boxes 201a and 202A, an open region in the dashed box 201a but not the open region in the dashed box 202A is filled with Al, a open region in the dashed box 202A but not the open region in the dashed box 201a is filled with Ge, but the dashed boxes 201a and 202A further have an opening overlapping region, and the overlapping region forms an opening indicated by a mark 203 d; the dashed box 203b corresponds to the registration pattern at the dashed box 201b, and it can be seen that the openings of the dashed box 201b are filled with Al; the dashed box 203c corresponds to the registration pattern at the dashed box 202b, and it can be seen that the openings of the dashed box 202b are all filled with Ge.

As shown in fig. 2D, the photograph corresponds to the pattern region 203a of fig. 2C, and the opening pattern 203D is visible in the photograph, and the opening pattern 203D has a certain offset. However, after eutectic bonding of the second silicon wafer 103 and the first silicon wafer 102, the offset of the opening pattern 203d cannot be measured because the opening pattern 203d is inside, not on the surface, of the entire structure composed of the second silicon wafer 103 and the first silicon wafer 102 after bonding.

Disclosure of Invention

The invention aims to solve the technical problem of providing a test structure for measuring eutectic bonding alignment deviation, which can effectively monitor the alignment precision of a bonding machine.

In order to solve the above technical problem, in the test structure for measuring eutectic bonding alignment deviation provided by the present invention, eutectic bonding is achieved between the first silicon wafer and the second silicon wafer through the first bonding material layer formed on the first surface of the first silicon wafer and the second bonding material layer formed on the first surface of the second silicon wafer.

The test structure comprises a plurality of top silicon strips formed on the first surface of the first silicon wafer and a second bonding material block formed on the first surface of the second silicon wafer, wherein a first bonding material layer is formed on the surface of each top silicon strip.

And each top layer silicon strip is used as a scale of alignment deviation of the eutectic bonding, and when the alignment deviation of the eutectic bonding occurs, the second bonding material block is bonded with the first bonding material layer at the top of the top layer silicon strip at the corresponding position.

The second block of bonding material is connected to the first test pad; the first bonding material layer of each top silicon strip top is connected with a corresponding second test pad.

And when the alignment deviation of the eutectic bonding is measured, measuring the conduction relation between the first test pad and each second test pad, and when the first test pad and the corresponding second test pad are conducted, indicating that the second bonding material block is bonded with the first bonding material layer at the top of the top silicon strip at the corresponding position, so as to determine the alignment deviation of the eutectic bonding.

The further improvement is that each top silicon strip is in a parallel arrangement structure.

In a further improvement, each of the top silicon strips is arranged in parallel at equal intervals.

In a further improvement, when eutectic bonding is performed between the first silicon wafer and the second silicon wafer, the second bonding material block is eutectic bonded with more than one top silicon strip.

A further improvement is a silicon-based MEMS motion sensor formed on the first silicon wafer.

In a further improvement, the silicon-based MEMS motion sensor comprises a fixed electrode and a movable electrode, and a groove is arranged between the fixed electrode and the movable electrode.

In a further improvement, the second surface of the first silicon wafer is bonded to a third silicon wafer.

The third silicon wafer is used as a sealing cover layer of the first silicon wafer.

In a further improvement, a cavity is formed in the third silicon wafer, the cavity corresponding in position to the movable electrode and providing space for movement of the movable electrode.

In a further improvement, the first silicon wafer and the third silicon wafer are bonded through silicon dioxide.

In a further improvement, a buried oxide layer is isolated between each top silicon strip and the bottom silicon consisting of the first silicon wafer.

In a further improvement, a CMOS integrated circuit is formed on the second silicon wafer, and the CMOS integrated circuit is used for controlling the silicon-based MEMS motion sensor.

In a further improvement, a first search mark is formed on the first surface of the first silicon wafer by patterning a first bonding material layer.

And a second search mark formed by patterning a second bonding material layer is formed on the first surface of the second silicon wafer.

In a further improvement, after the first silicon wafer and the second silicon wafer are eutectic bonded, the first search mark and the second search mark are mutually aligned.

In a further improvement, the silicon-based MEMS motion sensor is of the type including a pressure sensor, an acceleration sensor.

In a further refinement, the first bonding material includes germanium; the second bonding material includes aluminum.

The invention arranges a plurality of positions on a first silicon wafer of eutectic bonding to determine a top silicon strip as a scale of alignment deviation, and arranges a second bonding material block on a second silicon wafer, when the alignment deviation of the eutectic bonding is different, the second bonding material block can be bonded with a first bonding material layer on the surface of the top silicon strip at different positions, the second bonding material block and the first bonding material layer on the surface of the top silicon strip are respectively connected with a first test pad and a second test pad, and a second test pad corresponding to the first bonding material layer of the eutectic bonding of the second bonding material block can be conducted with the first test pad, so that the top silicon strip bonded with the second bonding material block can be determined by testing the conduction relation between the second test pad corresponding to the top silicon strip and the first test pad, and the position of the top silicon strip is predetermined, therefore, the alignment deviation can be obtained, and the alignment precision of the bonding machine table can be effectively monitored.

Drawings

The invention is described in further detail below with reference to the following figures and detailed description:

FIG. 1 is a schematic diagram of a prior art silicon-based MEMS motion sensor;

FIG. 2A is a schematic diagram of a prior art Gesearchmark;

FIG. 2B is a schematic of a prior art Alsearchmark;

FIG. 2C is a schematic illustration of the registration of FIGS. 2A and 2B;

FIG. 2D is a photograph corresponding to the graphic area 203a of FIG. 2C;

FIG. 3A is a top view of a test structure for measuring eutectic bonding alignment deviations, according to an embodiment of the present invention;

fig. 3B is a sectional view along line AA in fig. 3A.

Detailed Description

FIG. 3A is a top view of a test structure for measuring eutectic bonding alignment deviation according to an embodiment of the present invention; fig. 3B is a cross-sectional view along line AA in fig. 3A. The test structure for measuring the alignment deviation of eutectic bonding comprises the following steps:

eutectic bonding is achieved between the first silicon wafer 301 and the second silicon wafer 302 through a first bonding material layer 305 formed on the first surface of the first silicon wafer 301 and a second bonding material layer formed on the first surface of the second silicon wafer 302.

The test structure comprises a plurality of top silicon bars 303 formed on a first surface of the first silicon wafer 301, and a second block of bonding material 306 formed on a first surface of the second silicon wafer 302, wherein a first layer of bonding material 305 is formed on the surface of each top silicon bar 303.

In the embodiment of the present invention, each of the top silicon strips 303 is in a parallel arrangement structure.

The top silicon strips 303 are arranged in parallel at equal intervals.

The first bonding material includes germanium; the second bonding material includes aluminum.

A buried oxide layer 304 is isolated between each top silicon strip 303 and the bottom silicon consisting of the first silicon wafer 301.

Each top-layer silicon strip 303 is used as a scale for alignment deviation of the eutectic bonding, and when the alignment deviation of the eutectic bonding occurs, the second bonding material block 306 is bonded with the first bonding material layer 305 on the top of the top-layer silicon strip 303 at the corresponding position.

When eutectic bonding is performed between the first silicon wafer 301 and the second silicon wafer 302, the second bonding material block 306 is eutectic bonded to the more than one top silicon bar 303.

The second block of bonding material 306 is connected to the first test pad by a wire 308; the first bonding material layer 305 on top of each of the top silicon strips 303 is connected to a corresponding second test pad by a respective link 307.

When the alignment deviation of the eutectic bonding is measured, conducting relations between the first test pads and the second test pads are measured, and when the first test pads and the corresponding second test pads are conducted, the first test pads and the corresponding second test pads represent that the second bonding material blocks 306 are bonded with the first bonding material layers 305 on the tops of the top-layer silicon strips 303 at the corresponding positions, so that the alignment deviation of the eutectic bonding is determined.

In an embodiment of the present invention, a silicon-based MEMS motion sensor is formed on the first silicon wafer 301. The silicon-based MEMS motion sensor according to the embodiment of the present invention may refer to the silicon-based MEMS motion sensor on the first silicon wafer 102 shown in fig. 1.

The silicon-based MEMS motion sensor comprises a fixed electrode and a movable electrode, wherein a groove is arranged between the fixed electrode and the movable electrode at an interval.

The silicon-based MEMS motion sensor comprises a pressure sensor and an acceleration sensor.

And bonding the second surface of the first silicon wafer 301 with a third silicon wafer. The structure of the third silicon wafer according to the embodiment of the present invention can be seen from the structure of the third silicon wafer 101 in fig. 1.

The third silicon wafer serves as a capping layer for the first silicon wafer 301.

A cavity is formed on the third silicon wafer, the cavity corresponding in position to the movable electrode and providing a space for movement of the movable electrode.

The first silicon wafer 301 and the third silicon wafer are bonded through silicon dioxide.

A CMOS integrated circuit is formed on the second silicon wafer 302, and the CMOS integrated circuit is used for controlling the silicon-based MEMS motion sensor. The structure of the second silicon wafer 302 according to the embodiment of the present invention can be seen from the structure of the second silicon wafer 103 in fig. 1.

First search marks formed by patterning a first bonding material layer 305 are formed on a first surface of the first silicon wafer 301. The first search mark may refer to Gesearchmark shown in FIG. 2A.

A second search mark patterned from a second bonding material layer is formed on the first surface of the second silicon wafer 302. The second search mark may refer to Alsearchmark shown in fig. 2B.

After the first silicon wafer 301 and the second silicon wafer 302 are eutectic bonded, the first search mark and the second search mark are mutually aligned. The registration pattern of the embodiment of the present invention may refer to the registration pattern shown in fig. 3B.

In the embodiment of the invention, a plurality of top silicon strips 303 are arranged on a first silicon wafer 301 which is subjected to eutectic bonding and used as scales of alignment deviation, a second bonding material block 306 is arranged on a second silicon wafer 302, when the sizes of the alignment deviation of the eutectic bonding are different, the second bonding material block 306 is bonded with first bonding material layers 305 on the surfaces of the top silicon strips 303 at different positions, the second bonding material block 306 and first bonding material layers 305 on the surfaces of the top silicon strips 303 are also respectively connected with a first test pad and a second test pad, a second test pad corresponding to the first bonding material layer 305 which is subjected to eutectic bonding with the second bonding material block 306 is conducted with the first test pad, so that the top silicon strips 303 bonded with the second bonding material blocks 306 can be determined by testing the conduction relationship between the second test pads corresponding to the top silicon strips 303 and the first test pads, the position of the top silicon strip 303 is predetermined, so that alignment deviation can be obtained, and the embodiment of the invention can effectively monitor the alignment precision of a bonding machine.

The present invention has been described in detail with reference to the specific embodiments, but these should not be construed as limitations of the present invention. Many variations and modifications may be made by one of ordinary skill in the art without departing from the principles of the present invention, which should also be considered as within the scope of the present invention.