Auxiliary device for measuring morphology of infrared detector chip

Abstract

The invention relates to an auxiliary device for morphology measurement of an infrared detector chip, relates to the technical field of chip welding, and is used for solving the problem that the stability and reliability of a device are influenced by increase of blind pixels in a local area of the chip due to overlarge pressure. A vacuum cavity is formed in the body, a communicating hole is formed in the body, and one end of the communicating hole is communicated with the vacuum cavity. The warping correction structure is arranged at one end of the body, and the warping correction structure communicates with the vacuum cavity; and the suction assembly communicates with the other end of the communicating hole. The auxiliary device can simulate the state of the infrared detector chip on the welding arm of the face-down welding machine, and at the moment, the surface appearance of the infrared detector chip is completely the same as the appearance during interconnection. Therefore, the morphology measurement deviation caused by chip warping is avoided, the accuracy of the measurement value is ensured, and the pressure value during chip flip interconnection can be finally determined.

Description

Technical Field

[0001] The invention relates to the technical field of chip welding, and in particular to an auxiliary device for measuring the morphology of an infrared detector chip. Background Art

[0002] At present, the infrared detector chip is usually loaded into the flip chip bonder for flip chip interconnection. The chip (infrared detector chip) is fixed on the bonding arm of the flip chip bonder by vacuum adsorption for flip chip interconnection welding. Under normal circumstances (ideal plane), the chip welding requires 12 kg of pressure (empirical value), but because the chip surface has 3 microns of fluctuation, in order to overcome the influence of this 3 microns, the interconnection pressure needs to be increased by 3 kg (empirical value) to complete the welding.

[0003] If the deviation value on the chip surface is caused by the uneven thickness of the chip, it is correct to use a pressure of 15 kg for interconnection when it is sucked by the bonding arm.

[0004] However, if the 3-micron deviation is caused by the warping of the chip, when it is adsorbed by the welding arm, the vacuum and atmospheric pressure will flatten the warped part and eliminate the 3-micron deviation. At this time, if the same 15-kilogram pressure is used for flip-chip interconnection, the pressure will be obviously too high. Excessive pressure will cause the number of blind pixels in the local area of ​​the detector chip to increase, affecting the stability and reliability of the device.

[0005] That is to say, in the chip flip-chip interconnection process, there is a problem in the prior art that excessive pressure causes an increase in blind pixels in a local area of ​​the chip, thus affecting the stability and reliability of the device. Summary of the invention

[0006] The invention provides an auxiliary device for measuring the morphology of an infrared detector chip, which is used to solve the problem that excessive pressure causes an increase in blind pixels in a local area of ​​the chip, thereby affecting the stability and reliability of the device.

[0007] The present invention provides an auxiliary device for measuring the morphology of an infrared detector chip, comprising:

[0008] A body, in which a vacuum chamber is arranged, and a connecting hole is arranged on the body, one end of the connecting hole is connected with the vacuum chamber; and

[0009] a warp correction structure disposed on one end of the body, the warp correction structure being in communication with the vacuum chamber; and

[0010] a suction assembly connected to the other end of the communication hole;

[0011] The suction component evacuates the vacuum chamber and the warp correction structure through the connecting hole. When the warp correction structure is in a vacuum state, the warp correction structure can absorb and correct the infrared detector chip.

[0012] In one embodiment, the vacuum chamber is an open chamber, and the opening of the open chamber is arranged on an end of the body away from the warp correction structure, wherein when the suction component evacuates the vacuum chamber and the warp correction structure through the connecting hole, the opening is adsorbed on the sample stage.

[0013] In one embodiment, the communication hole is provided on the outer circumference of the body along a radial extension of the body.

[0014] In one embodiment, the central axis of the vacuum chamber coincides with the central axis of the body.

[0015] In one embodiment, the body is a cylinder, and / or the suction assembly is a vacuum pump.

[0016] In one embodiment, the warp correction structure comprises:

[0017] A vacuum suction hole is provided on one end of the body extending along the second direction, and one end of the vacuum suction hole is communicated with the vacuum chamber; and

[0018] a correction slot disposed on one end of the body;

[0019] Among them, the vacuum suction hole is arranged in the correction groove, and when the warping correction structure is in a vacuum state, the correction groove is used to absorb and correct the infrared detector chip.

[0020] In one embodiment, the correction slot comprises:

[0021] A first linear groove extending along a first direction and disposed on one end of the body; and

[0022] The second linear groove is extended along the third direction and is arranged on one end of the body. The second linear groove is arranged to cross the first linear groove.

[0023] In one embodiment, the first linear groove and the second linear groove are in a cross-shaped configuration.

[0024] In one embodiment, the vacuum suction hole is located at the intersection of the first linear groove and the second linear groove.

[0025] In one embodiment, the correction groove further includes an annular groove, which is disposed on one end of the body, wherein the first linear groove and the second linear groove are both located in the annular groove and communicated with the annular groove.

[0026] Compared with the prior art, the advantage of the present invention is that the auxiliary device can adsorb and correct the infrared detector chip under vacuum adsorption. In this way, the state of the infrared detector chip on the welding arm of the flip soldering machine can be simulated, and the surface morphology of the infrared detector chip is exactly the same as the morphology during interconnection. This avoids the morphology measurement deviation caused by chip warping, thereby ensuring the accuracy of the measurement value, so that the pressure value during the flip-chip interconnection can be finally determined, so that in the flip-chip interconnection process, the problem of increasing blind pixels in the local area of ​​the infrared detector chip caused by excessive pressure, which affects the stability and reliability of the device, can be effectively avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Hereinafter, the present invention will be described in more detail based on embodiments and with reference to the accompanying drawings.

[0028] Figure 1 is a schematic diagram of the three-dimensional structure of an auxiliary device for measuring the morphology of an infrared detector chip in an embodiment of the present invention;

[0029] Figure 2 yes Figure 1 A schematic diagram of the three-dimensional structure of the auxiliary device from another angle;

[0030] Figure 3 yes Figure 1 Schematic diagram of the assembly relationship between the auxiliary device and the infrared detector chip (the chip has not been corrected);

[0031] Figure 4 yes Figure 1 Schematic diagram of the assembly relationship between the auxiliary device and the infrared detector chip (the chip has been rectified);

[0032] Figure 5 yes Figure 3 The surface morphology of the chip in the middle is measured in a free state;

[0033] Figure 6 yes Figure 3 The chip surface morphology measured under medium vacuum adsorption state;

[0034] Figure 7 It is a schematic diagram of welding of infrared detector chip in the prior art;

[0035] Figure 8 This is a schematic diagram of the infrared detector chip placed on the sample stage (the difference is caused by chip warping);

[0036] Fig. 9 This is a schematic diagram of the infrared detector chip placed on the sample stage (the difference is caused by the uneven thickness of the chip);

[0037] Fig.10 yes Fig. 9Schematic diagram of the infrared detector chip being adsorbed by the welding arm;

[0038] Fig.11 yes Figure 8 Schematic diagram of the infrared detector chip being adsorbed by the welding arm.

[0039] Reference numerals:

[0040] 10. Main body; 11. Vacuum chamber; 12. Connecting hole; 20. Warp correction structure; 21. Vacuum suction hole; 22. Correction groove; 221. First linear groove; 222. Second linear groove; 223. Annular groove; 100. Infrared detector chip; 200. Sample stage; 300. Readout circuit. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the accompanying drawings.

[0042] Infrared focal plane detectors (infrared detectors) are widely used in infrared thermal imaging, infrared remote sensing, search and rescue, and other fields. In its preparation process, flip-chip interconnection is one of the key technologies. Its main process is to press-weld the infrared detector chip and the readout circuit 300 together through indium columns, so that the light signal detected by the infrared detector is processed and output through the readout circuit. Flip-chip interconnection is completed by a flip-chip welder, and the main operating steps are as follows:

[0043] Step 1: Place the readout circuit with the front side facing up on the vacuum hole in the center of the base of the flip chip bonder, and fix the circuit on the platform by vacuum adsorption.

[0044] Step 2: Place the detector chip face down on the sample holder next to the bonding platform, and use a tool with a vacuum suction hole to suck up the chip. Use a microscope to adjust and align the detector chip with the readout circuit.

[0045] Step 3: Set the interconnection pressure, interconnection temperature and time parameters, operate the welding arm to drive the tool with vacuum suction hole to move downward, and press the chip and the readout circuit together (see Figure 7 ).

[0046] Ideally, the surface of the readout circuit and the surface of the detector are both flat. However, due to limitations in the processing technology, the surface of the detector is not an ideal plane and has varying degrees of warping, surface undulations, and uneven thickness.

[0047] Therefore, in order to improve the yield of flip-chip interconnection, the detector surface needs to be topographically measured before interconnection, and the interconnection parameters such as interconnection pressure and leveling state need to be adjusted according to the chip surface topography.

[0048] Compared with the readout circuit chip, the surface flatness of the infrared detector chip is much worse due to the limitations of materials and manufacturing processes. Therefore, in the actual process, only the surface morphology of the infrared detector chip is measured. The measurement process is:

[0049] Place the detector chip to be measured on the sample stage of a profilometer or interferometer to measure its topographic features and calculate the height difference. The difference between the highest point and the lowest point on the chip surface is 3 microns (see Figure 8 and Fig. 9 ).

[0050] It should be noted that the current measurement equipment measures the topography and height difference of the chip surface, and cannot simultaneously measure the topography of the bottom (back) surface of the chip. Based on this difference alone, we cannot determine whether the 3-micron difference is caused by chip warpage (see Figure 8 ), or is it caused by uneven chip thickness (see Fig. 9 ).

[0051] The chip is loaded into the flip chip bonder for flip chip interconnection. The chip is fixed on the bonding arm of the flip chip bonder by vacuum adsorption for flip chip interconnection welding. Under normal circumstances (ideal plane), the chip welding requires a pressure of 12 kg (empirical value), but because the chip surface has 3 microns of fluctuation, in order to overcome the influence of this 3 microns, the interconnection pressure needs to be increased by 3 kg (empirical value) to complete the welding.

[0052] If the deviation value on the chip surface is caused by the uneven thickness of the chip, it will be like Fig.10 As shown, it is correct to use a pressure of 15 kg for interconnection.

[0053] However, if the 3 micron deviation is caused by the warping of the chip, when it is adsorbed by the bonding arm, the warped part will be flattened due to the effect of vacuum and atmospheric pressure (see Fig.11 ), eliminating the 3 micron deviation. At this point, if 15 kg of pressure is used for flip-chip interconnection, the pressure is obviously too high.

[0054] That is to say, in the flip-chip interconnection process, excessive pressure will lead to an increase in blind pixels in local areas of the detector chip, affecting the stability and reliability of the device.

[0055] To overcome the above defects, Figures 1 to 4As shown, the present invention provides an auxiliary device for measuring the morphology of an infrared detector chip, and the auxiliary device includes a body 10, a warp correction structure 20, and a suction assembly. The body 10 is provided with a vacuum chamber 11, and a connecting hole 12 is provided on the body 10, and one end of the connecting hole 12 is connected to the vacuum chamber 11; the warp correction structure 20 is provided on one end of the body 10, and the warp correction structure 20 is connected to the vacuum chamber 11; the suction assembly is connected to the other end of the connecting hole 12; the suction assembly vacuumizes the vacuum chamber 11 and the warp correction structure 20 through the connecting hole 12, and when the warp correction structure 20 is in a vacuum state, the warp correction structure 20 can adsorb and correct the infrared detector chip 100.

[0056] In the above setting, the auxiliary device can adsorb and correct the infrared detector chip 100 under vacuum adsorption. In this way, the state of the infrared detector chip on the welding arm of the flip soldering machine can be simulated, and the surface morphology of the infrared detector chip is exactly the same as the morphology during interconnection. Thereby avoiding the deviation of the morphology measurement caused by chip warping, and then ensuring the accuracy of the measurement value, so that the pressure value and the leveling angle during the chip flip-chip interconnection can be finally determined (according to the measured chip surface morphology map, it can be determined to use the above-mentioned 15 kg pressure or the above-mentioned 12 kg pressure), so that in the flip-chip interconnection process, it can effectively avoid the increase of blind pixels in the local area of ​​the infrared detector chip caused by the use of excessive pressure or wrong leveling angle, which affects the stability and reliability of the device.

[0057] It should be noted that, by using the auxiliary device provided by the present invention, the surface morphology of the chip (infrared detector chip 100) is measured under vacuum adsorption state, simulating the state of the chip on the welding arm of the reverse welding machine. At this time, the surface morphology of the chip is exactly the same as the morphology during interconnection, which can avoid the morphology measurement deviation caused by chip warping in the prior art and make the measurement value more accurate.

[0058] Specifically, Figures 2 to 4 As shown, in one embodiment, the vacuum chamber 11 is an open chamber, and the opening of the open chamber is arranged on one end of the body 10 away from the warp correction structure 20, wherein when the suction component evacuates the vacuum chamber 11 and the warp correction structure 20 through the connecting hole 12, the opening is adsorbed on the sample stage 200. In this way, when the suction component evacuates, it can drive the warp correction structure 20 to work so that it adsorbs and corrects the infrared detector chip 100. At the same time, it can also adsorb the opening on the sample stage 200. Thus, the auxiliary device and the sample stage 200 are fixed.

[0059] Specifically, Figures 1 to 4 As shown, in one embodiment, the communication hole 12 is provided on the outer circumference of the body 10 along a radial extension of the body 10 .

[0060] Specifically, Figure 3 and Figure 4 As shown, in one embodiment, the central axis of the vacuum chamber 11 coincides with the central axis of the body 10 .

[0061] Specifically, Figure 3 and Figure 4 As shown, in one embodiment, the body 10 is a cylinder, and the vacuum chamber 11 is a circular open chamber.

[0062] Specifically, in one embodiment, the suction assembly employs a vacuum pump.

[0063] Specifically, Figure 1 As shown, in one embodiment, the warpage correction structure 20 includes a vacuum suction hole 21 and a correction groove 22. The vacuum suction hole 21 is arranged on one end of the body 10 extending along the second direction, and one end of the vacuum suction hole 21 is connected to the vacuum chamber 11; the correction groove 22 is arranged on one end of the body 10; the vacuum suction hole 21 is arranged in the correction groove 22, and when the warpage correction structure 20 is in a vacuum state, the correction groove 22 is used to absorb and correct the infrared detector chip 100.

[0064] It should be noted that the suction component evacuates the vacuum chamber 11 and the warping correction structure 20 through the connecting hole 12. Since one end of the vacuum suction hole 21 is connected to the vacuum chamber 11, the vacuum suction hole 21 is arranged in the correction groove 22. In this way, the air in the correction groove 22 will be sucked away. Since the infrared detector chip 100 is placed on the correction groove 22, the correction groove 22 can adsorb the infrared detector chip 100. Since the contact area between the correction groove 22 and the infrared detector chip 100 is large, the contact area is also the adsorption area of ​​the correction groove 22. Such a sufficiently large adsorption area can ensure that the infrared detector chip 100 can be placed flat and tightly adsorbed on one end of the body 10. Thereby, the correction of the infrared detector chip 100 is achieved. At this time, the infrared detector chip 100 is measured again, thereby avoiding the morphological measurement deviation caused by chip warping in the prior art, thereby ensuring the accuracy of the measurement value.

[0065] Specifically, Figure 1 As shown, in one embodiment, the correction groove 22 includes a first linear groove 221 and a second linear groove 222. The first linear groove 221 is arranged on one end of the body 10 extending along a first direction; the second linear groove 222 is arranged on one end of the body 10 extending along a third direction, and the second linear groove 222 is arranged to cross the first linear groove 221.

[0066] Specifically, Figure 1 As shown, in one embodiment, the first linear groove 221 and the second linear groove 222 are in a "cross" shape.

[0067] Specifically, as Figure 1 shown, in one embodiment, the vacuum suction holes 21 are located at the intersection of the first linear groove 221 and the second linear groove 222.

[0068] Specifically, as Figure 1 shown, in one embodiment, the correction groove 22 further includes an annular groove 223, and the annular groove 223 is provided at one end of the body 10. Among them, the first linear groove 221 and the second linear groove 222 are both located in the annular groove 223 and communicate with the annular groove 223.

[0069] Specifically, as Figure 1 shown, in one embodiment, the annular groove 223 is a square groove. Of course, the size of the groove can be designed according to the actual size of the sample to be measured.

[0070] Specifically, as Figure 1 shown, in one embodiment, the correction groove 22 is in a "field" - shaped structure.

[0071] It should be noted that the "field" - shaped structure is designed because the chip to be measured is usually rectangular. In order to increase the force - bearing area when the chip to be measured is vacuum - adsorbed, make the chip受力均匀, and be adsorbed more firmly. The length and width of the "field" are slightly smaller than the length and width of the chip to be measured, that is, the area of the "field" is slightly smaller than the area of the chip to be measured. When measuring, the chip to be measured can completely cover the correction groove 22 to ensure that the chip is firmly adsorbed. (In addition, when the chip is倒装互连, the vacuum suction holes on the adsorption fixture for倒装互连 are also in the same "field" - shaped structure.

[0072] It should be noted that, as Figure 1 shown, the front surface of the auxiliary device is provided with vacuum suction holes 21, which are used to adsorb the infrared detector chip. The back surface of the auxiliary device is provided with a relatively large circular vacuum chamber 11, which is used to adsorb and fix this device on the sample stage 200 of the measuring device. There is a vacuum tube (arranged in the communication hole 12) on the side of the auxiliary device, which is used to connect to an external vacuum pump, and the inside of this tube is in communication with both the vacuum suction holes 21 and the vacuum chamber 11. The material of the auxiliary device is aluminum alloy.

[0073] When measuring the surface topography of the chip, first place the vacuum adsorption device (auxiliary device) face - up on the sample stage, and then place the infrared detector chip to be measured on the vacuum adsorption holes on the front surface of the auxiliary device. The infrared detector chip should cover the adsorption holes. Connect the vacuum pump. Turn on the vacuum pump and start pumping vacuum for this device.

[0074] If the infrared detector chip has warpage deformation, then under the action of vacuum, the warpage deformation will be corrected (see Figure 4 ). At this time, when measuring again, the actual topography of the surface of the infrared detector chip can be measured.

[0075] If the infrared detector chip does not have any warping deformation, the warping correction structure will not have an adverse effect on the measurement of the infrared detector chip morphology, and its measurement data will be true.

[0076] like Figure 5 As shown in Figure 1, it is the measured surface morphology of the chip in the free state. Figure 6 As shown, it is the surface morphology measured under vacuum adsorption state.

[0077] Depend on Figure 5 and Figure 6 By comparison, DA and DB are the measured heights of point A and point B respectively. Figure 5 In the test, the measuring equipment found that point A is the highest point on the chip, and point B is the lowest point on the chip. The height difference between points A and B is 3.7 microns, that is, DA-DB = 3.7um. Figure 6 This is the data measured by the same chip under vacuum adsorption. The height difference between point A and point B becomes 0.6 microns, that is, DA-DB = 0.6um. It can be seen from the two pictures that Figure 6 Compare Figure 5 If you look at it from the side, Figure 5 Just like Figure 3 The status shown, Figure 6 Just like Figure 4 The state shown. The surface morphology of the infrared detector chip in the vacuum adsorption state is obviously different. Figure 6 This is the surface morphology measured under the actual welding state.

[0078] It should be noted that the present application avoids the shape measurement deviation caused by the warping of the infrared detector chip, making the measurement value more accurate, and then making the parameter setting of the flip-chip interconnection more accurate, thereby improving the yield rate of the flip-chip interconnection process. The manufacturing process level of the infrared detector chip is improved, and the warping and deformation of the chip are reduced.

[0079] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An auxiliary device for measuring the morphology of an infrared detector chip, characterized in that: include: A body (10) having a vacuum chamber (11) disposed therein, the body (10) being provided with a communication hole (12), one end of the communication hole (12) being in communication with the vacuum chamber (11); and a warping correction structure (20), which is arranged on one end of the body (10), and the warping correction structure (20) is connected to the vacuum chamber (11); and A suction assembly connected to the other end of the communication hole (12); The suction component evacuates the vacuum chamber (11) and the warp correction structure (20) through the connecting hole (12); when the warp correction structure (20) is in a vacuum state, the warp correction structure (20) can absorb and correct the infrared detector chip (100).

2. The auxiliary device for measuring the morphology of an infrared detector chip according to claim 1, characterized in that: The vacuum chamber (11) is an open chamber, and the opening of the open chamber is arranged on an end of the main body (10) away from the warp correction structure (20), wherein when the suction component evacuates the vacuum chamber (11) and the warp correction structure (20) through the connecting hole (12), the opening is adsorbed on the sample stage (200).

3. The auxiliary device for measuring the morphology of an infrared detector chip according to claim 2, characterized in that: The communication hole (12) is arranged on the outer periphery of the body (10) and extends along the radial direction of the body (10).

4. The auxiliary device for measuring the morphology of an infrared detector chip according to claim 2, characterized in that: The central axis of the vacuum chamber (11) coincides with the central axis of the body (10).

5. The auxiliary device for measuring the morphology of an infrared detector chip according to claim 2, characterized in that: The main body (10) is a cylindrical body, and / or the suction component adopts a vacuum pump.

6. The auxiliary device for measuring the morphology of an infrared detector chip according to any one of claims 1 to 5, characterized in that: The warping correction structure (20) comprises: a vacuum suction hole (21) extending along the second direction and arranged on one end of the body (10), one end of the vacuum suction hole (21) being connected to the vacuum chamber (11); and A correction groove (22) disposed on one end of the body (10); The vacuum suction hole (21) is arranged in the correction groove (22); when the warp correction structure (20) is in a vacuum state, the correction groove (22) is used to absorb and correct the infrared detector chip (100).

7. The auxiliary device for measuring the morphology of an infrared detector chip according to claim 6, characterized in that: The correction groove (22) comprises: A first linear groove (221) extending along a first direction and disposed on one end of the body (10); and A second linear groove (222) is provided on one end of the body (10) and extends along a third direction. The second linear groove (222) is provided to cross the first linear groove (221).

8. The auxiliary device for measuring the morphology of an infrared detector chip according to claim 7, characterized in that: The first linear groove (221) and the second linear groove (222) are in a "cross" shape.

9. The auxiliary device for measuring the morphology of an infrared detector chip according to claim 7 or 8, characterized in that: The vacuum suction hole (21) is located at the intersection of the first linear groove (221) and the second linear groove (222).

10. The auxiliary device for measuring the morphology of an infrared detector chip according to claim 7 or 8, characterized in that: The correction groove (22) further comprises an annular groove (223), wherein the annular groove (223) is arranged on one end of the body (10), wherein the first linear groove (221) and the second linear groove (222) are both located in the annular groove (223) and are in communication with the annular groove (223).

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