High-sensitivity, high-precision and anti-interference blade height measuring circuit of wafer cutting machine

Abstract

The invention provides a high-sensitivity, high-precision and anti-interference blade height measurement circuit of a wafer cutting machine, and relates to the technical field of blade height measurement of wafer cutting machines. The height measurement circuit comprises a current sampling circuit, a filtering and amplifying circuit and a misconduction suppression circuit; the current sampling circuit is used for sampling a current signal of a loop formed when a blade of the wafer cutting machine is in contact with a chassis of the wafer cutting machine, and filtering an internal interference signal of the wafer cutting machine; the filtering and amplifying circuit is used for performing active filtering on a high-frequency interference signal at a main shaft of the wafer cutting machine and amplifying a filtered sampling signal; the misconduction suppression circuit is used for isolating and suppressing interference signals triggered by water vapor and oil mist in the working process of the wafer cutting machine. The circuit is simple in structure and flexible in parameter adjustment, and the problems of height measurement signal false triggering caused by internal interference of the wafer cutting machine and height measurement delay, large errors and system failure caused by large contact resistance are solved.

Description

Technical Field

[0001] The invention relates to the technical field of wafer cutting machine blade height measurement, in particular to a high-sensitivity, high-precision, anti-interference wafer cutting machine blade height measurement circuit. Background Art

[0002] In the production process of semiconductor devices, a wafer cutter (dicing machine) is used to cut the processed wafers with a rotating blade to separate the semiconductor devices to be packaged from the wafer waste. The height of the cutting machine blade from the workbench (chassis) is very important, which determines the actual cutting depth. If it is too shallow, the semiconductor device cannot be completely separated from the wafer. If it is too deep, it will cause the workbench or blade to be damaged when cutting to the chassis. Therefore, it is necessary to keep the blade at an appropriate height during the cutting process. There are two existing blade height measurement methods: non-contact height measurement and contact height measurement. Non-contact height measurement uses a fiber optic amplifier to measure the blade height, converting the blade light shielding amount when the spindle descends into an analog voltage, and stopping the blade from descending when it reaches the threshold. However, due to the large amount of water vapor and oil mist generated by the cooling in the cutting chamber during cutting, the light flux of the fiber optic amplifier will be blocked, which seriously affects the height measurement results and leads to large measurement errors. Contact height measurement is achieved by detecting whether there is contact between the blade and the workbench. A constant voltage is applied between the blade and the workbench. When the blade contacts the workbench, a current loop is formed between the blade and the workbench, which pulls down the voltage signal. When it is lower than a specific threshold, a trigger signal is generated, and the cutting axis is lifted to prevent the blade from further contacting the workbench. However, the multiple stepper motors inside the wafer cutting machine will bring serious interference signals during operation, mainly concentrated on the chassis and spindle of the wafer cutting machine. In addition, there is a large amount of water vapor and oil mist generated when the temperature drops in the cutting chamber of the wafer cutting machine, which causes the height measurement circuit to be misconnected and generate interference signals, causing the wafer cutting machine to work abnormally. For these two parts of interference, capacitors with larger capacitance are generally used for filtering, but when the blade contact resistance is higher than 500KΩ, the circuit delay will be too large, resulting in a decrease in system sensitivity, and the height measurement data will be too large, which will inevitably leave scratches on the chassis of the wafer cutting machine and damage the wafer and equipment. The contact resistance between the blade and the workbench varies depending on the blade material and can reach up to 15MΩ. As the contact resistance continues to increase, the current loop signal will be too weak to drive the circuit components to work, causing the height measurement function to fail.

[0003] To solve the above problems, this patent proposes a high-sensitivity, high-precision, anti-interference wafer cutting machine blade height measurement circuit, which can achieve high-sensitivity, high-precision blade height control within the full range of high interference and blade contact resistance, thereby improving the stability and reliability of the wafer cutting machine. Summary of the invention

[0004] The purpose of the present invention is to provide a high-sensitivity, high-precision, anti-interference wafer cutting machine blade height measurement circuit, aiming to solve the problem of wafer cutting machine blade height measurement with high interference and in the full range of blade head contact resistance.

[0005] The present invention is implemented as follows: a high-sensitivity, high-precision, anti-interference wafer cutting machine blade height measurement circuit includes three parts: a current sampling circuit, a filtering and amplifying circuit, and a mis-conduction suppression circuit.

[0006] The current sampling circuit is used to sample the current signal of a loop formed when the wafer cutting machine blade contacts the wafer cutting machine chassis and filter the internal interference signal of the wafer cutting machine, and includes a first resistor, a second resistor, and a first capacitor.

[0007] One end of the first resistor is connected to the wafer cutting machine spindle; the other end of the first resistor is connected to one end of the second resistor and one end of the first capacitor to form the output end of the current sampling circuit; the other end of the second resistor is grounded; the other end of the first capacitor is grounded.

[0008] The filtering and amplifying circuit is used to actively filter the high-frequency interference signal inside the wafer cutting machine and amplify the filtered sampling signal, and includes a first operational amplifier, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a second capacitor, and a third capacitor.

[0009] One end of the third resistor is connected to the output end of the current sampling circuit, and the other end of the third resistor is connected to one end of the fourth resistor and one end of the third capacitor; the other end of the fourth resistor is connected to one end of the second capacitor and the non-inverting input end of the first operational amplifier; one end of the fifth resistor is connected to one end of the sixth resistor and the inverting input end of the first operational amplifier; the other end of the fifth resistor is grounded; the other end of the sixth resistor is connected to the other end of the third capacitor and the output end of the first operational amplifier, forming the output end of the filtering and amplifying circuit; the other end of the second capacitor is grounded.

[0010] The mis-conduction suppression circuit is used to isolate and suppress interference signals that are falsely triggered by water vapor and oil mist during the operation of the wafer cutting machine, and includes a first solid-state relay, a seventh resistor, an eighth resistor, and a fourth capacitor.

[0011] One end of the seventh resistor is connected to the output end of the filtering and amplifying circuit, and the other end of the seventh resistor is connected to one end of the fourth capacitor and the first input end of the first solid-state relay; one end of the eighth resistor is connected to the first output end of the first solid-state relay, constituting the output end of the wafer cutting machine blade height measurement circuit; the other end of the eighth resistor is connected to the power supply output end; the other end of the fourth capacitor is grounded.

[0012] Beneficial effects:

[0013] The present invention provides a high-sensitivity, high-precision, anti-interference wafer cutting machine blade height measurement circuit, comprising a current sampling circuit, a filtering and amplifying circuit, and a mis-conduction suppression circuit. The circuit structure is simple and the parameters can be adjusted flexibly. The circuit solves the problems of false triggering of the height measurement signal caused by internal interference in the wafer cutting machine and height measurement sluggishness, large errors, and system failure caused by large contact resistance, thereby achieving the characteristics of high sensitivity, high precision, and anti-interference of the height measurement circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of a high-sensitivity, high-precision, anti-interference wafer cutting machine blade height measurement circuit provided by the present invention. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0016] Figure 1 This is a circuit structure diagram of a high-sensitivity, high-precision, anti-interference wafer cutting machine blade height measurement circuit provided by an embodiment of the present invention. For the sake of convenience, only the parts related to the present invention are shown. As shown in the figure: a high-sensitivity, high-precision, anti-interference wafer cutting machine blade height measurement circuit includes three parts: a current sampling circuit, a filtering and amplifying circuit, and a misleading conduction suppression circuit.

[0017] The current sampling circuit includes a first resistor R1, a second resistor R2, and a first capacitor C1.

[0018] One end of the first resistor R1 is connected to the spindle of the wafer cutting machine; the other end of the first resistor R1 is connected to one end of the second resistor R2 and one end of the first capacitor C1 to form the output end V of the current sampling circuit. sense ; The other end of the second resistor R2 is grounded; The other end of the first capacitor C1 is grounded.

[0019] The filtering and amplifying circuit includes a first operational amplifier U1, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a seventh resistor R6, a second capacitor C2, and a third capacitor C3.

[0020] One end of the third resistor R3 is connected to the output end V of the current sampling circuit sense, the other end of the third resistor R3 is connected to one end of the fourth resistor R4 and one end of the third capacitor C3; the other end of the fourth resistor R4 is connected to one end of the second capacitor C2 and the non-inverting input end of the first operational amplifier U1; one end of the fifth resistor R5 is connected to one end of the sixth resistor R6 and the inverting input end of the first operational amplifier U1; the other end of the fifth resistor R5 is grounded; the other end of the sixth resistor R6 is connected to the other end of the third capacitor C3 and the output end of the first operational amplifier U1, forming an output end V of the filtering and amplifying circuit out ; The other end of the second capacitor C2 is grounded.

[0021] The mis-conduction suppression circuit includes a first solid-state relay U2, a seventh resistor R7, an eighth resistor R8, and a fourth capacitor C4.

[0022] One end of the seventh resistor R7 is connected to the output end V out The other end of the seventh resistor R7 is connected to one end of the fourth capacitor C4 and the first input end of the first solid-state relay U2; one end of the eighth resistor R8 is connected to the first output end of the first solid-state relay U2 to form the output end LB of the wafer cutting machine blade height measurement circuit; the other end of the eighth resistor R8 is connected to the power output end V + ; The other end of the fourth capacitor C4 is grounded.

[0023] Below through Figure 1 The implementation scheme of the circuit shown specifically describes the implementation principle of the present invention:

[0024] The current sampling circuit samples the current signal of the circuit formed when the wafer cutting machine blade contacts the wafer cutting machine chassis, and filters the internal interference signal of the wafer cutting machine. The wafer cutting machine spindle has high-frequency interference, and the chassis has low-frequency interference. Connect the chassis to the power output terminal V + Clamp the chassis level and suppress chassis interference. For high-frequency interference signals at the spindle, a capacitor with a smaller capacitance value can meet the filtering requirements, greatly reducing circuit delay, reducing height measurement errors, and improving circuit sensitivity and accuracy.

[0025] When the wafer cutting machine blade contacts the wafer cutting machine chassis, the current sampling circuit and the wafer cutting machine form a power output terminal V + → chassis → blade → spindle → first resistor R1 → second resistor R2 → reference ground series loop, the second resistor R2 converts the loop current signal into a voltage signal V sense .

[0026] like Figure 1 As shown, the contact resistance between the wafer cutting machine blade and the wafer cutting machine chassis is R 接触 , according to the voltage division characteristics of the series circuit, we have:

[0027]

[0028] The first capacitor C1 and the first resistor R1 form a passive RC low-pass filter to filter the high-frequency interference signal at the remaining spindle.

[0029] Assume the passive RC filter cutoff frequency is f cutoff-w , according to the RC filter cutoff frequency calculation formula:

[0030]

[0031] Assume that the frequency of the high-frequency interference signal at the spindle of the wafer cutting machine is f noise In order to filter it out as cleanly as possible, f cutoff-w As small as possible, let f cutoff-w =f noise / 6, then the capacitance C1 is determined by the following formula:

[0032]

[0033] The filtering and amplifying circuit performs active filtering on the high-frequency interference signal at the spindle of the wafer cutting machine and amplifies the filtered sampling signal. Among them, the third resistor R3, the fourth resistor R4, the second capacitor C2, the third capacitor C3 and the first operational amplifier U1 constitute an active filter to perform active filtering on the high-frequency interference signal at the spindle, further improving the filtering effect and the circuit sensitivity. Assume that the cutoff frequency of the active filter is f cutoff-y , which is determined by the following formula:

[0034]

[0035] For the convenience of design, take R3=R4, C2=C3, then:

[0036]

[0037] Similarly, let f cutoff-w =f noise / 6, then:

[0038]

[0039] The fifth resistor R5 and the sixth resistor R6 convert the voltage signal V sense Amplification is used to improve the driving capability of the first solid-state relay U2 in the mis-conduction suppression circuit, and solve the problem of failure of the circuit height measurement function under large contact resistance. Assuming the amplification factor is A, it is determined by the fifth resistor R5 and the sixth resistor R6 according to the following formula:

[0040]

[0041] Assume the output voltage of the filter and amplifier circuit is V out,but:

[0042] V out =V sense ×A

[0043] By adjusting the resistance values ​​of the fifth resistor R5 and the sixth resistor R6, the filter and amplifier circuit outputs V out The turn-on voltage requirement of the first solid-state relay U2 in the mis-turn-on suppression circuit is met.

[0044] The mis-conduction suppression circuit isolates and suppresses the interference signals falsely triggered by water vapor and oil mist during the operation of the wafer cutting machine. Since the start-up signal establishment time of the first solid-state relay U2 is in milliseconds, which is greater than the duration of the interference signals falsely triggered by water vapor and oil mist during the operation of the wafer cutting machine, the duration of the false triggering interference signal does not meet the start-up signal establishment time of the first solid-state relay U2, thereby achieving the effect of isolating and suppressing the interference signals falsely triggered during the operation of the wafer cutting machine.

[0045] The effective control signal required by the wafer cutting machine blade is a low level. When the wafer cutting machine blade contacts the wafer cutting machine chassis, the filter and amplifier circuit outputs a signal V out The false conduction suppression circuit turns on the first solid-state relay U2, and its output terminal is turned on to form the power output terminal V + →The eighth resistor R8→the reference ground loop pulls down the output LB level of the wafer cutting machine blade height measurement circuit, and the circuit outputs a low effective control signal; when the wafer cutting machine blade does not contact the wafer cutting machine chassis, the first solid-state relay U2 is not turned on, and the wafer cutting machine blade height measurement circuit output LB is a high level V + , the circuit has no effective control signal output.

[0046] like Figure 1 As shown in the mis-conduction suppression circuit, assume that the current at the first input terminal of the first solid-state relay U2 is I f , the voltage drop between the first input terminal and the second input terminal is V f , then the seventh resistor R7 is determined by the following formula:

[0047]

[0048] The fourth capacitor C4 and the seventh resistor R7 form an RC low-pass filter, which is effective for the frequency f noise The remaining high-frequency interference signal is filtered, and f cutoff-w =f noise / 6, which is determined by the following formula:

[0049]

[0050] Assume that the current at the first output terminal of the first solid-state relay U2 is Io , then the eighth resistor R8 is determined by the following formula:

[0051]

[0052] According to the above circuit analysis, the overall working principle of the high-sensitivity, high-precision, anti-interference wafer cutting machine blade height measurement circuit of the present invention is: when the wafer cutting machine blade contacts the wafer cutting machine chassis, the wafer cutting machine and the current sampling circuit form a loop, and the current sampling circuit collects the loop current signal and converts it into a voltage signal V sense At the same time, the low-frequency interference at the chassis is transmitted through the power output terminal V + Clamp, filter out chassis interference, use first-order RC filter circuit to filter high-frequency interference at the remaining spindle; filter and amplifier circuit actively filter high-frequency interference and amplify the filtered voltage signal to V out The output is given to the mis-conduction suppression circuit, so that the first solid-state relay U2 is turned on and the output terminal LB of the wafer cutting machine blade height measurement circuit is pulled down, and a low effective control signal is output; when the wafer cutting machine blade does not contact the wafer cutting machine chassis, the first solid-state relay U2 is not turned on, and the output terminal LB of the circuit is a high level V + , the height measurement circuit has no effective control signal output. The wafer cutting machine chassis is connected to the power output terminal V + , clamp the chassis level to filter out low-frequency interference, and use the millisecond-level start signal of the first solid-state relay in the mis-conduction suppression circuit to establish time isolation to suppress the interference signal of the wafer cutting machine's water vapor and oil mist false triggering, and jointly achieve high anti-interference of the circuit. For the high-frequency interference signal at the remaining spindle, a small-capacitance capacitor can meet the filtering requirements, greatly reducing the circuit delay; the filtering and amplification circuit actively filters the remaining high-frequency interference signal and amplifies the filtered sampling signal, solving the problem of failure of the circuit height measurement function under large contact resistance, and further improving the filtering effect, and jointly achieving high sensitivity of the circuit. The smaller delay makes the height measurement circuit measure the difference smaller in both large and small contact resistance, meeting the accuracy requirements of the contact resistance of the cutting machine head in the full range, and can detect the error caused by the wear of the cutting head in real time to achieve high-precision measurement.

[0053] The high-sensitivity, high-precision, anti-interference wafer cutting machine blade height measurement circuit proposed in the present invention has a compact structure and a small number of components. It has high precision while reducing circuit delay and can solve various interference problems, thereby ensuring sensitive and stable height measurement.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein by equivalents. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-sensitivity, high-precision, anti-interference wafer cutting machine blade height measurement circuit, characterized in that: include: A current sampling circuit is used to sample the current signal of a loop formed when the wafer cutting machine blade contacts the wafer cutting machine chassis, and to filter the internal interference signal of the wafer cutting machine; The filtering and amplifying circuit is used to actively filter the high-frequency interference signal inside the wafer cutting machine and amplify the filtered sampling signal; The mis-conduction suppression circuit is used to isolate and suppress interference signals caused by false triggering of water vapor and oil mist during the operation of the wafer cutting machine.

2. The current sampling circuit according to claim 1, characterized in that: The current sampling circuit includes a first resistor, a second resistor, and a first capacitor. One end of the first resistor is connected to the spindle of the wafer cutting machine; the other end of the first resistor is connected to one end of the second resistor and one end of the first capacitor to form the output end of the current sampling circuit; the other end of the second resistor is grounded; and the other end of the first capacitor is grounded.

3. The filtering and amplifying circuit according to claim 1, characterized in that: The filtering and amplifying circuit includes a first operational amplifier, a third resistor, a fourth resistor, a fifth resistor, a seventh resistor, a second capacitor, and a third capacitor. One end of the third resistor is connected to the output end of the current sampling circuit, and the other end of the third resistor is connected to one end of the fourth resistor and one end of the third capacitor; the other end of the fourth resistor is connected to one end of the second capacitor and the non-inverting input end of the first operational amplifier; one end of the fifth resistor is connected to one end of the sixth resistor and the inverting input end of the first operational amplifier; the other end of the fifth resistor is grounded; the other end of the sixth resistor is connected to the other end of the third capacitor and the output end of the first operational amplifier, forming the output end of the filtering and amplifying circuit; the other end of the second capacitor is grounded.

4. The mis-conduction suppression circuit according to claim 1, characterized in that: The misconduction suppression circuit includes a first solid-state relay, a seventh resistor, an eighth resistor, and a fourth capacitor. One end of the seventh resistor is connected to the output end of the filtering and amplifying circuit, and the other end of the seventh resistor is connected to one end of the fourth capacitor and the first input end of the first solid-state relay; one end of the eighth resistor is connected to the first output end of the first solid-state relay, constituting the output end of the wafer cutting machine blade height measurement circuit; the other end of the eighth resistor is connected to the power supply output end; the other end of the fourth capacitor is grounded.

5. The current sampling circuit according to claim 1, characterized in that: The wafer cutting machine chassis is connected to the power supply output terminal to clamp the chassis level and suppress chassis interference.

6. The mis-turn-on suppression circuit according to claim 1, characterized in that: The first solid-state relay start-up signal establishment time is greater than the duration of the interference signal falsely triggered by water vapor and oil mist during the operation of the wafer cutting machine.

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