Thermally driven microbeam bending strength online detection system, manufacturing method and application

Abstract

The application discloses a kind of micro beam bending strength online detection system based on heat drive, manufacturing method and application, belong to microelectronic mechanical system field.This online detection system includes on-chip testing machine and on-chip test sample, on-chip testing machine mainly includes heat drive loading executor, double-beam heat insulation structure, V-shaped amplification lever, region of interest positioning mark structure and double hammer head structure, and on-chip test sample mainly includes rigid block structure, bending test beam and elastic suspension folded beam.The on-chip testing machine of the application relies on its own resistance beam heating to load and release energy, can realize the full-automatic bending fracture strength online detection and test result extraction after power-on, and can be used for monitoring deep etching release process and predicting the reliability of MEMS device structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of micro-electro-mechanical system (MEMS), and particularly discloses a micro-beam bending strength online detection system based on thermal driving, a manufacturing method and application. BACKGROUND

[0002] Micro-electro-mechanical system (MEMS) is an advanced technology integrating microelectronics technology and mechanical engineering, mainly used for manufacturing miniaturized sensors and actuators. Compared with traditional devices, MEMS devices have the advantages of small size, light weight, low energy consumption, small inertia, high resonance frequency, short response time, high sensitivity and easy integration, and are widely used in various aspects of consumer electronics, automobile industry, chemical industry, medicine and even professional fields with extreme environment. Products manufactured based on this technology include pressure gauges, gyroscopes, catalytic sensors, electrostatic braking light projection displays, etc.

[0003] As one of the main means for manufacturing movable structures in MEMS technology, the deep reactive ion etching (DRIE) process has different degrees of etching surface unevenness in actual manufacturing process. The existence of this phenomenon will directly lead to the presence of randomly distributed micro-cracks or micro-damage defects on the side wall of the movable structure in the etching process, thereby affecting the actual fracture strength of the microstructure and causing serious process reliability problems. Therefore, it is crucial to realize the quality monitoring and reliability detection of the process by extracting the fracture strength of the microstructure manufactured by the DRIE process. Among them, the bending fracture strength of the micro-beam is one of the most important parameters.

[0004] At present, there are many common methods for extracting the bending fracture strength of materials, including four-point bending test applied to traditional off-chip testing machines and equal strength cantilever beam concentrated force bending applied to on-chip testing machines. The traditional four-point bending test cannot realize the fixation, clamping and loading of micro-scale structures, while the equal strength cantilever beam concentrated force bending applied to on-chip testing machines cannot accurately characterize the quality of the deep reactive ion etching process because it cannot obtain the starting position of the etching crack (surface or internal) through testing. At the same time, for on-chip bending fracture strength testing, the common loading method is to apply displacement load through a probe table probe, which has positioning deviation and cannot exclude the problem of causing great damage to the device structure due to accidental error operation when operating the probe. The above methods all have certain limitations for process quality monitoring and device structure reliability prediction of deep etching process, so a measurement method that can avoid the above limitations is needed. SUMMARY

[0005] In view of the above-mentioned problems, the present application provides a micro-beam bending strength online detection system based on thermal drive, a manufacturing method and application, which can be manufactured together with functional devices to obtain a test sample structure.

[0006] The present application adopts the following technical solutions:

[0007] The present application adopts the following technical solutions:

[0008] The on-chip tester comprises two thermal drive loading actuators, two double-beam heat insulation structures, a V-shaped amplification lever, a region of interest positioning mark structure, a double hammer head structure and two pairs of first fixed anchor points, which are symmetric about the center line of the on-chip tester; the thermal drive loading actuator is composed of a plurality of groups of parallel V-shaped thermal drive beams, the two ends of each group of V-shaped thermal drive beams are connected to a pair of first fixed anchor points, and the middle corners of each group of V-shaped thermal drive beams are connected to each other; one end of the double-beam heat insulation structure is connected to the inner side of the middle corner of the V-shaped thermal drive beam, and the other end is connected to one end of the V-shaped amplification lever; one side of the region of interest positioning mark structure is connected to the middle part of the V-shaped amplification lever, and the other side is connected to the double hammer head structure; the double hammer head structure comprises two conical hammer heads.

[0009] The on-chip test sample comprises two rigid block structures, a bending test beam, two elastic suspension folding beams and two third fixed anchor points and two fourth fixed anchor points, which are symmetric about the center line of the on-chip test sample; the two ends of the bending test beam are connected to the two rigid block structures and are opposite to the double hammer head structure; the two third fixed anchor points are located on the side of the bending test beam away from the double hammer head structure and are spaced apart, and are located in the middle position of the two conical hammer heads; one end of the elastic suspension folding beam is connected to the rigid block structure, and the other end is connected to the fourth fixed anchor point.

[0010] Further, each thermal drive loading actuator is composed of 10 groups of V-shaped thermal drive beams with equal width, equal length and equal spacing.

[0011] Further, the double-beam heat insulation structure is composed of two mutually parallel slender beams, and the part between the two slender beams is hollow.

[0012] Further, the middle part of the region of interest positioning mark structure contains three rectangular grooves with the same size and spacing.

[0013] Further, the two conical hammer heads in the double hammer head structure are arc-shaped, and the groove part between the two conical hammer heads is in the shape of an isosceles trapezoid.

[0014] Further, the on-chip testing machine further comprises two second fixed anchor points located at the lateral sides of the double-hammer-head structure.

[0015] Further, the first and fourth fixed anchor points can be square, rectangular or parallelogram in shape; the second fixed anchor point is rectangular in shape; and the third fixed anchor point is circular arc-shaped at the head and rectangular at the tail.

[0016] Further, the elastic suspension folding beam is composed of a plurality of elastic beams in series.

[0017] A manufacturing method of a micro-beam bending strength online detection system based on thermal driving, comprising the following steps of manufacturing an on-chip testing machine:

[0018] Photolithography and anisotropic etching are performed on the front surface of the silicon wafer to form fixed anchor points, including the first to fourth fixed anchor points.

[0019] Photolithography and wet etching are performed on the glass surface to form a shallow groove, and then the metal is sputtered in the shallow groove and the interconnection metal pattern is defined by stripping to obtain the anti-lateral etching electrode.

[0020] The silicon wafer and the glass wafer are anodically bonded, and the anti-lateral etching electrode on the glass is pressed into the fixed anchor point area of the silicon wafer.

[0021] The back surface of the silicon wafer is thinned by a wet etching process, and a layer of SiO2 is deposited on the back surface of the silicon wafer as a hard mask.

[0022] A groove structure with the same thickness as the hard mask is formed on the back surface of the silicon wafer by photolithography and etching process, serving as a silicon surface electrode area.

[0023] A metal electrode is deposited in the silicon surface electrode area to serve as a voltage loading point of the thermal driving loading actuator.

[0024] The movable structure is released by photolithography and deep etching release process to obtain the on-chip testing machine.

[0025] Further, the silicon wafer is an N-type single crystal silicon wafer with a resistivity of 0.001-0.003 Ω·cm, and Ti, Pt and Au are sputtered in the shallow groove on the glass surface.

[0026] An application of a micro-beam bending strength online detection system based on thermal driving in micro-beam static four-point bending fracture strength detection, comprising the following steps:

[0027] The thermal driving loading actuator is powered on, and the thermal driving voltage is increased from 0V to a preset value in sequence to control the loading deflection of the double-hammer-head structure; under different thermal driving voltages, the bending test beam is subjected to static bending loading, and the static bending deformation of the bending test beam is observed.

[0028] If the bending test beam does not occur bending fracture, the hot drive loading actuator is powered off, and after the hot drive loading actuator returns to room temperature, the hot zone loading actuator is powered on again until the bending test beam is successfully fractured, and the voltage value at this time is recorded;

[0029] The loading deflection is read by an image sub-pixel edge analysis measurement system, and the read loading deflection and the corresponding voltage value are brought into a COMSOL simulation model for simulation, so as to obtain the static bending fracture strength of the bending test beam.

[0030] The beneficial effects obtained by the present application are as follows:

[0031] 1) The online detection system of the present application can exclude the accidental error operation defects of the traditional four-point bending test beam, and realize a new type of full-automatic test;

[0032] 2) The online detection system of the present application avoids the error of the actual loading deflection caused by the Joule heat generated when the hot drive loading actuator is powered on by introducing a double-beam heat insulation structure;

[0033] 3) The online detection system of the present application directly realizes the reading of the loading deflection by introducing a region of interest positioning mark structure through an image sub-pixel edge analysis measurement method, and improves the measurement accuracy;

[0034] 4) The online detection system of the present application can realize the successful positioning and clamping of the loaded chip under test by introducing rigid block structures and elastic suspension folding beams on both sides of the bending test beam;

[0035] 5) The online detection system of the present application can perform static four-point bending test on the bending test beam of a micro-scale structure;

[0036] 6) The online detection system of the present application can perform process monitoring and reliability prediction of device structures on the bending test beam. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a structure schematic diagram of the micro-beam bending strength online detection system based on hot drive in the embodiment of the present application.

[0038] Explanation of reference signs:

[0039] 1: hot drive loading actuator;

[0040] 2: double-beam heat insulation structure;

[0041] 3: V-shaped amplification lever;

[0042] 4: region of interest positioning mark structure;

[0043] 5: Double hammer head structure;

[0044] 6: Rigid block structure;

[0045] 7: Bending test beam;

[0046] 8: Elastic suspension folding beam;

[0047] 9: First fixed anchor point;

[0048] 10: Second fixed anchor point;

[0049] 11: Third fixed anchor point;

[0050] 12: Fourth fixed anchor point.

[0051] Figure 2 is a side view of a hot-driven micro-beam bending strength online detection system in an embodiment of the present application.

[0052] Figures 3A-3H is a manufacturing flow chart of a chip-on-tester in an embodiment of the present application.

[0053] Legend of reference signs:

[0054] 31: Silicon wafer;

[0055] 32: Anti-lateral etching electrode;

[0056] 33: Glass wafer;

[0057] 34: Fixed anchor point;

[0058] 35: Hard mask;

[0059] 36: Silicon surface electrode area;

[0060] 37: Metal electrode;

[0061] 38: Movable structure. DETAILED DESCRIPTION

[0062] In order to make the above features and advantages of the present application more obvious and easy to understand, the following specific examples are described in detail below, and the accompanying drawings are described as follows. Those skilled in the art can understand the structure, advantages and effects of the present application from the content disclosed in the following examples. The present application can also be implemented or applied by other different specific examples, and each detail in the specification can be modified and changed in various ways based on different views and applications without departing from the concept and scope of the present application.

[0063] The present embodiment discloses a hot-driven micro-beam bending strength online detection system, comprising: a chip-on-tester and a chip-on-die under test, the structure is as shown in Figure 1 and Figure 2 .

[0064] The on-chip test machine includes two thermal-driven actuators 1, two double-beam thermal-isolation structures 2, one V-shaped amplification lever 3, one region of interest (RIO) positioning mark structure 4, one double-hammer-head structure 5, and two pairs of first fixed anchor points 9 and two second fixed anchor points 10. The overall structure of the on-chip test machine is symmetric about the center line. For ease of description, the orientation of the center line is referred to as the vertical direction, and the perpendicular direction is referred to as the horizontal direction.

[0065] The thermal-driven actuator 1 is composed of 10 groups of V-shaped thermal-driven beams with equal width, equal length, and equal spacing, and all in the order of microns. The middle corners of the V-shaped thermal-driven beams in each group are connected to each other. To ensure that the output displacement of the thermal-driven actuator 1 is always in the horizontal direction, the two thermal-driven actuators 1 are symmetrically distributed on both sides of the on-chip test machine about the center line. The vertical ends of the thermal-driven actuator 1 are connected to the two first fixed anchor points 9, and the inner side of the middle position is connected to the double-beam thermal-isolation structure 2.

[0066] One side of the double-beam thermal-isolation structure 2 is connected to the thermal-driven actuator 1, and the other side is connected to the V-shaped amplification lever 3. To avoid the error caused by the actual loading deflection of the V-shaped amplification lever 3 due to the Joule heat generated when the thermal-driven actuator 1 is powered on, the double-beam thermal-isolation structure 2 is composed of two parallel slender beams. The part between the two slender beams is hollowed out to avoid the generation of Joule heat.

[0067] The RIO positioning mark structure 4 is connected to the lower side of the middle part of the V-shaped amplification lever 3. The middle of the RIO positioning mark structure 4 contains three rectangular grooves with the same size and spacing. The lower side of the RIO positioning mark structure 4 is connected to the double-hammer-head structure 5. The double-hammer-head structure 5 includes two circular-arc-shaped conical hammer heads, and the groove part between the two conical hammer heads is shaped as an isosceles trapezoid. To limit the horizontal movement of the double-hammer-head structure 5 during movement, two rectangular second fixed anchor points 10 are distributed on the horizontal sides of the structure.

[0068] The on-chip device under test includes two rigid block structures 6, one curved test beam 7, two elastic suspension folded beams 8, two third fixed anchor points 11, and two fourth fixed anchor points 12, which are symmetric about the center line of the on-chip device under test (coinciding with the center line of the on-chip test machine).

[0069] The bending test beam 7 is arranged transversely, with the upper side facing the double hammer head structure 5 and the lower side symmetrically provided with two third fixed anchor points 11 located in the middle of the two conical hammer heads. When the double hammer head structure 5 is not driven, there is a gap between the double hammer head structure 5 and the bending test beam 7, and there is a certain gap between the bending test beam 7 and the third fixed anchor points 11. The third fixed anchor points 11 are in the shape of a circular arc head and a rectangular tail. The bending test beam 7 is connected to a rigid block structure 6 at each of the two ends in the transverse direction. The elastic suspension folding beam 8 is composed of a plurality of parallel elastic beams connected in series to form a plurality of repeated back-and-forth structures. The upper end of the elastic suspension folding beam 8 is connected to the rigid block structure 6, and the lower end is connected to a fourth fixed anchor point 12. The design of the rigid block structure 6 and the elastic suspension folding beam 8 can achieve the positioning and clamping of the bending test beam 7 on the wafer.

[0070] The embodiment also discloses a manufacturing method of a micro-beam bending strength online detection system based on thermal driving. The method mainly comprises a manufacturing step of a wafer test machine, and a manufacturing process thereof is shown in Figures 3A-3H The process is based on a standard process of bonding deep etching and release, and mainly comprises the following steps:

[0071] (1) As shown in Figure 3A , the silicon wafer 31 is an N-type single crystal silicon wafer with a resistivity of 0.001-0.003 Ω·cm and a thickness of 400 μm. The silicon wafer 31 is etched by photolithography and ASE anisotropic etching to form a step with an etching depth of 4 μm (in other embodiments, the etching depth can be selected in the range of 4-12 μm according to actual needs), thereby forming anchor points 34, including first to fourth fixed anchor points, on the front surface of the silicon wafer 31.

[0072] (2) As shown in Figure 3B , the glass wafer 33 is 7740 with a thickness of 500±10 μm. A shallow groove is prepared on the surface of the glass wafer 33 by photolithography and BHF wet etching process, and the depth of the shallow groove is PVD sputtering of metal Ti / Pt / Au with a thickness of and definition of interconnection metal pattern by a stripping process to prepare a footing electrode 32.

[0073] (3) As shown in Figure 3C , the obtained silicon wafer 31 and glass wafer 33 are anodically bonded, and the footing electrode 32 on the glass wafer 33 is pressed into the anchor point 34 area.

[0074] (4) As shown in Figure 3D , the back surface of the silicon wafer 31 is thinned by a KOH wet etching process, and the remaining thickness is 60 μm.

[0075] (5) As shown in Figure 3EAs shown, a layer of SiO2 film is PVD-sputtered on the back of the silicon wafer 31 as a hard mask 35, the thickness of which is To ensure the loading of large current.

[0076] (6) Figure 3F As shown, a groove structure having the same thickness as the hard mask 35 is formed on the back side of the silicon wafer 31 by combining photolithography, dry etching and wet etching to serve as the silicon surface electrode region 36 .

[0077] (7) Figure 3G As shown, metal aluminum is deposited on the silicon surface electrode region 36 to form a metal electrode 37, which serves as the voltage loading point of the thermal drive loading actuator 1. The thickness of the electrode metal 37 is About , refer to the actual thickness of the hard mask 35 mentioned above.

[0078] (8) Figure 3H As shown, the structure is released by photolithography and DRIE dry etching process to obtain a suspended movable structure 38. The movable structure 38 is each structure of the on-chip test machine and the on-chip test sample except for each anchor point.

[0079] This embodiment also discloses an application of a micro-beam bending strength online detection system based on thermal drive, which is used to detect the static four-point bending fracture strength of the micro-beam, and includes the following steps:

[0080] 1) The thermal drive loading actuator is powered on through the silicon surface electrode area, and the thermal drive voltage is increased from 0V to the corresponding design value (the thermal drive voltage range is within 0-10V), thereby controlling the loading deflection of the double hammer head structure;

[0081] 2) Under different thermal drive voltages, static bending loading is performed on the bending test beam to observe the static bending deformation of the bending test beam;

[0082] 3) If the bending test beam does not break, first power off the thermal drive loading actuator. After the thermal drive loading actuator returns to room temperature, that is, after the system is adjusted to stable, power on the thermal drive loading actuator again. The thermal drive voltage is increased by 0.5V each time until the bending test beam successfully breaks. The voltage value at this time is recorded.

[0083] 4) Through the image sub-pixel edge analysis measurement system to read the loading deflection under the corresponding voltage, and the above-mentioned loading deflection and the corresponding voltage value into the established machine-electric-thermal coupling integrated model, in COMSOL simulation software to carry out the simulation of static four-point bending whole process, thereby obtaining the corresponding deformation of the bending test beam and its corresponding static bending fracture strength under different voltage values and different loading deflections. In this example, the static bending fracture strength of the bending test beam is about 1.2Gpa.

[0084] The present application adds a detection area containing the system to a silicon wafer with functional devices, and the improved SOG (silicon on glass) process is used to manufacture functional devices and detection systems. After the overall process is completed, the static four-point bending fracture strength of the sample is detected by the system, and the process-related mechanical property parameters of the functional devices are obtained online.

[0085] The above examples are only used to describe the technical solutions of the present application, but not for limitation. The structural features and characteristics of the well-known common knowledge are not described in detail. It should be pointed out that for those skilled in the art, without departing from the technical concept of the present application, the on-chip tester structure can be modified and improved in several ways, which should be considered as falling within the scope of the present application. The protection scope of the present application is subject to the scope defined by the claims.

Claims

1. A micro-beam bending strength online detection system based on thermal drive, characterized in that: include: On-chip tester and on-chip test sample; The on-chip test machine includes: two thermal drive loading actuators, two dual-beam thermal insulation structures, a V-shaped amplifying lever, a region of interest positioning mark structure, a double hammer structure, and two pairs of first fixed anchor points, all of which are symmetrical about the center line of the on-chip test machine; the thermal drive loading actuator is composed of several groups of parallel V-shaped thermal drive beams, the two ends of each group of V-shaped thermal drive beams are connected to a pair of first fixed anchor points, and the middle corners of each group of V-shaped thermal drive beams are connected to each other; one end of the dual-beam thermal insulation structure is connected to the inner side of the middle corner of the V-shaped thermal drive beam, and the other end is connected to one end of the V-shaped amplifying lever; one side of the region of interest positioning mark structure is connected to the middle part of the V-shaped amplifying lever, and the other side is connected to the double hammer structure; the double hammer structure includes two conical hammers; The on-chip test sample includes: two rigid block structures, a bending test beam, two elastic suspension folding beams, two third fixed anchor points, and two fourth fixed anchor points, all of which are symmetrical about the midline of the on-chip test sample; the two ends of the bending test beam are connected to the two rigid block structures and are opposite to the double hammer head structure; the two third fixed anchor points are located on the side of the bending test beam away from the double hammer head structure with a gap, and are located in the middle of the two conical hammer heads; one end of the elastic suspension folding beam is connected to the rigid block structure, and the other end is connected to the fourth fixed anchor point.

2. The micro-beam bending strength online detection system based on thermal drive according to claim 1, characterized in that: Each thermal drive loading actuator is composed of 10 groups of V-shaped thermal drive beams with equal width, length and interval.

3. The online detection system for micro-beam bending strength based on thermal drive according to claim 1, characterized in that: The double-beam insulation structure is composed of two slender beams parallel to each other, and the part between the two slender beams is hollow.

4. The online detection system for micro-beam bending strength based on thermal drive according to claim 1, characterized in that: The middle portion of the region of interest positioning marker structure contains three rectangular grooves of the same size and the same spacing.

5. The micro-beam bending strength online detection system based on thermal drive according to claim 1, characterized in that: The two conical hammer heads in the double hammer head structure are in an arc shape, and the groove portion between the two conical hammer heads is in an isosceles trapezoid shape.

6. The micro-beam bending strength online detection system based on thermal drive according to claim 1, characterized in that: The on-chip tester further includes two second fixed anchor points located on both lateral sides of the double hammer head structure.

7. The online detection system for micro-beam bending strength based on thermal drive according to claim 1, characterized in that: The elastic suspension folding beam is composed of a number of elastic beams parallel to each other and connected in series.

8. A method for manufacturing a micro-beam bending strength online detection system based on thermal drive according to any one of claims 1 to 7, characterized in that: The steps for manufacturing a test-on-chip include: Performing photolithography and anisotropic etching on the front surface of the silicon wafer to form fixed anchor points, including first to fourth fixed anchor points; Photolithography and wet etching are performed on the glass surface to form shallow grooves, and then metal is sputtered in the shallow grooves and the interconnected metal pattern is defined by lift-off to obtain an anti-lateral undercutting electrode; Anodic bonding is performed on the silicon wafer and the glass wafer, and the anti-lateral drilling electrode on the glass is pressed into the fixed anchor area of ​​the silicon wafer; The back of the silicon wafer is thinned by a wet etching process, and a SiO2 layer is deposited on the back of the silicon wafer as a hard mask; A groove structure having the same thickness as the hard mask is formed on the back side of the silicon wafer by photolithography and etching processes to serve as a silicon surface electrode region; Depositing metal on the silicon surface electrode area to obtain a metal electrode, which serves as a voltage loading point for the thermally driven loading actuator; Through photolithography and deep etching release processes, the movable structure is released to obtain an on-chip test machine.

9. The manufacturing method according to claim 8, wherein: The silicon wafer is an N-type single crystal silicon wafer with a resistivity of 0.001 to 0.003 Ω·cm; Ti, Pt and Au are sputtered in shallow grooves on the glass surface.

10. An application of the thermal drive-based online micro-beam bending strength detection system according to any one of claims 1 to 7 in detecting the static four-point bending fracture strength of micro-beams, comprising the following steps: The thermal drive loading actuator was powered on, and the thermal drive voltage was increased from 0V to the preset value to control the loading deflection of the double hammer head structure. Under different thermal drive voltages, the bending test beam was subjected to static bending loading to observe the static bending deformation of the bending test beam. If the bending test beam does not break, first power off the thermal drive loading actuator. After the thermal drive loading actuator returns to room temperature, power on the hot zone loading actuator again until the bending test beam breaks successfully. Record the voltage value at this time. The loading deflection is read by the image sub-pixel edge analysis measurement system, and the read loading deflection and the corresponding voltage value are brought into the COMSOL simulation model for simulation to obtain the static bending fracture strength of the bending test beam.

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