Wafer inspection system and method

Abstract

The application discloses a wafer detection system and a detection method, which comprises a detection unit, a displacement unit, an analysis unit and a calculation unit. The detection unit comprises a signal transmitting module and a signal receiving module arranged on the two sides of the wafer in the first direction respectively. The detection unit transmits signal information to the calculation unit. The displacement unit drives the detection unit to move along the second direction. The analysis unit is electrically connected with the displacement unit. The analysis unit records data information of the displacement unit and transmits the data information to the calculation unit. The calculation unit collects data from the detection unit and the analysis unit and performs calculation. The thickness detection calculation is performed based on the detection system. The structure is simple, the detection precision of the detection unit is high, and the detection efficiency is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor detection equipment, in particular to a wafer detection system and a detection method. BACKGROUND

[0002] Wafer refers to a silicon wafer needed in semiconductor integrated circuit manufacturing, which is the basis of chip manufacturing. The size and specification of wafer have a great influence on its performance, and the size precision needs to be guaranteed at the micron level. Therefore, it is very important to detect the thickness size of wafer. SUMMARY

[0003] The purpose of the present application is to provide a wafer detection system and a detection method, which can quickly and accurately detect the thickness, presence or absence and placement angle of wafer, and has high efficiency.

[0004] In order to achieve the above purpose, the technical scheme adopted by the present application is: a wafer detection system, the center axis of the wafer is parallel to the second direction, comprising:

[0005] A detection unit, the detection unit comprises a signal emitting module and a signal receiving module arranged on both sides of the wafer in the first direction respectively, the signal emitting module emits a signal, the signal receiving module receives the signal from the signal emitting module, and the detection unit transmits signal information to a calculation unit;

[0006] A displacement unit, the displacement unit drives the detection unit to move along the second direction;

[0007] An analysis unit, the analysis unit is electrically connected with the displacement unit, the analysis unit records data information of the displacement unit and transmits the data information to the calculation unit;

[0008] A calculation unit, the calculation unit collects data from the detection unit and the analysis unit and performs calculation.

[0009] The beneficial effects of the above detection system are: the displacement unit drives the detection unit, realizes the displacement of the detection unit relative to the wafer, in the relative motion process of the detection unit and the wafer, the existence of the wafer will shield the signal emitting module, so that the signal receiving module cannot receive the signal, the detection unit transmits the related data information of signal change to the calculation unit, the calculation unit can calculate the number of wafers according to the number of signal changes; the analysis unit records the position data information of the displacement unit, and transmits the position data information to the calculation unit, the calculation unit combines the signal information and the position information, and can calculate the thickness of the wafer. When the detection unit uses optical signal, the precision is higher, and the detection effect is good.

[0010] A wafer detection method comprises the wafer detection system, and the specific steps are as follows:

[0011] S1, presetting the pitch L of the displacement unit, the resolution E of the analysis unit, and the calculation formula on the calculation unit;

[0012] S2, the signal transmitting module and the signal receiving module of the detection unit are arranged on the two sides of the wafer in the first direction respectively;

[0013] S3, the displacement unit drives the detection unit to move along the second direction;

[0014] S4, the signal transmitting module sends signals, and the signal receiving module receives signals;

[0015] S5, when the signal receiving module cannot receive signals, the calculation unit records the time t1 when the signal changes;

[0016] S6, when the signal receiving module receives signals again, the calculation unit records the time t2 when the signal changes;

[0017] S7, the analysis unit sends the resolution value E corresponding to the time t1 to the calculation unit; t1

[0018] S8, the analysis unit sends the resolution value E corresponding to the time t2 to the calculation unit; t2

[0019] S9, the calculation unit calculates the thickness of the wafer according to the calculation formula.

[0020] Further, the steps S3 and S4 can be performed simultaneously, or the step S4 can be performed before the step S3.

[0021] Further, the steps S5 and S7 can be performed simultaneously, the steps S6 and S8 can be performed simultaneously, or the steps S7 and S8 can be performed simultaneously.

[0022] The wafer detection method has the advantages that the calculation unit can be set according to the specifications of the displacement unit and the analysis unit, which is flexible; the direct displacement measurement is converted into time measurement and calculation related to the pitch and resolution, which is more accurate; the calculation unit is used for automatic calculation, which saves manpower and has good detection effect.

[0023] ​​Illustratively, the displacement unit comprises a base and a driving mechanism, the detection unit is arranged on the base, and the driving mechanism drives the base to move in the second direction, the driving mechanism comprises a rotating member, the rotating member rotates relative to the base, and the rotation of the rotating member is converted into the linear motion of the base. The linear motion is characterized by rotation, which is calculated by the relationship between the lead and the number of rotation, reduces the manual error or external factor interference when directly measuring the linear displacement, and improves the precision.

[0024] Further, the driving mechanism further comprises a connecting member, and the rotating member is connected with the base through the connecting member.

[0025] Further, the driving mechanism further comprises a motor, and the motor drives the rotating member to rotate, and optionally, the motor is a direct current motor or a servo motor.

[0026] Illustratively, the analysis unit is arranged on the rotating member, the analysis unit records the rotation data of the rotating member and transmits the rotation data to the calculation unit. The rotation data is recorded and transmitted by the analysis unit, the number of rotations of the rotating member is automatically detected and recorded according to the resolution of the analysis unit, and the accuracy of the detection result is ensured.

[0027] Illustratively, the calculation formula of the number of rotations of the rotating member is as follows: In the formula, N is the number of rotations of the rotating member, E t1 is the resolution output value of the analysis unit at t1 time, E t2 is the resolution output value of the analysis unit at t2 time, t1 time is the time when the signal emitted by the signal emitting module is first blocked by the wafer, and t2 time is the time when the signal emitted by the signal emitting module is last blocked by the wafer.

[0028] Illustratively, the calculation formula of the thickness of the wafer is as follows: In the formula, T is the thickness of the wafer, and L is the linear displacement distance of the detection unit driven by the base when the rotating member rotates one round.

[0029] Illustratively, the rotating member is a screw rod, a ball screw or a trapezoidal screw. It can be flexibly selected according to actual needs, and has high flexibility.

[0030] Illustratively, the analysis unit is a rotary encoder. The number of rotations of the rotating member is detected according to the resolution of the rotary encoder, the rotation amount of the rotating member can be converted into the displacement amount of the displacement unit / detection unit, and the thickness of the wafer is calculated by cooperating with the calculation unit, and the precision is high.

[0031] For example, the displacement unit is equipped with a laser rangefinder or a linear encoder, which detects the displacement of the displacement unit. The displacement of the displacement unit / detection unit can be directly calculated using laser ranging, which is simple, clear, and more intuitive. Detecting the displacement of the displacement unit / detection unit using a laser rangefinder or linear encoder allows for secondary verification of the displacement conversion results from the rotary encoder, ensuring the reliability and accuracy of the calculation unit's results and high data credibility.

[0032] Furthermore, the computing unit is connected to a display screen, which displays signal information from the detection unit, data information from the analysis unit, and calculation information, making it easier for technicians to observe the quantity, status, and thickness measurement results of the wafers in real time, thus enhancing convenience.

[0033] For example, the above wafer inspection method further includes the following steps:

[0034] S1', Preset the value of time difference Δt on the calculation unit;

[0035] S2' When the signal receiving module changes from a state where it can receive signals to a state where it cannot receive signals, it sends time data to the analysis unit and the calculation unit, and the calculation unit records the time t3.

[0036] S3' The calculation unit compares the values ​​of Δt and t3-t2. If Δt > t3-t2, it indicates that the gap between wafers is too small or the wafers are placed at an angle, and the calculation unit records the corresponding position. If Δt = t3-t2, it indicates that the gap between wafers meets the requirements. If Δt < t3-t2, it indicates that the gap between wafers is too large, or a wafer is missing or the wafers are placed at an angle, and the calculation unit records the corresponding position. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the detection system according to a preferred embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram illustrating the relationship between signal and time in a preferred embodiment of the detection unit of the present invention;

[0039] Figure 3 This is a schematic diagram of the structure of a displacement unit according to a preferred embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram illustrating the relationship between the resolution and time of the analysis unit in a preferred embodiment of the present invention.

[0041] Figure 5 This is a schematic flowchart of a preferred embodiment of the detection method of the present invention;

[0042] Figure 6This is a schematic flowchart of a detection method according to another preferred embodiment of the present invention. Detailed Implementation

[0043] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0044] As attached Figure 1 To be continued Figure 6 As shown, the wafer inspection system in this embodiment includes a detection unit, a displacement unit, an analysis unit, and a calculation unit. The displacement unit drives the detection unit to change position relative to the wafer. The detection unit includes a signal transmitting module and a signal receiving module. The signal transmitting module is used to emit signals, and the signal receiving module is used to receive signals from the signal transmitting module. The analysis unit is electrically connected to the displacement unit, records the data information of the displacement unit, and transmits the data information to the calculation unit. The calculation unit is connected to the detection unit. The detection unit transmits the detected signal data information to the calculation unit. The calculation unit performs calculations on the data from the detection unit and the analysis unit to calculate the thickness of the wafer.

[0045] To facilitate the description and understanding of the technical solution of this embodiment, the X-axis direction is defined as the first direction, and the Y-axis direction as the second direction. The central axis of the wafer is parallel to the second direction. The signal transmitting module and the signal receiving module are respectively disposed on both sides of the wafer in the first direction. The displacement unit drives the signal transmitting module and the signal receiving module to move along the second direction. When detecting a single wafer, the displacement unit drives the detection unit to move from one side of the wafer to the other side in the second direction. During this process, the relationship between the signal data information S of the detection unit and time t is shown in the appendix. Figure 2 As shown in (a):

[0046] At time t1, the signal emitted by the signal transmitting module begins to be blocked by the wafer. At time t2, the signal emitted by the signal transmitting module ends to be blocked by the wafer. Under these conditions, the detection unit sends the times t1 and t2 to the calculation unit, and the calculation unit calculates the thickness of the wafer.

[0047] In another example of this embodiment, since wafers are typically placed and stored in a dedicated container (such as a wafer cassette), when a robotic arm handles the wafers, it is usually necessary to detect the distribution of the wafers within the container to ensure that the robotic arm can perform the picking and placing actions correctly. When more than one wafer needs to be detected within the container, adjacent wafers are arranged in parallel, and the central axes of different wafers coincide. During the movement of the detection unit driven by the displacement unit, the signal information of the detection unit includes the following states:

[0048] State 1: The signal emitted by the signal transmitting module is blocked by the wafer, and the signal receiving module cannot receive the signal. In this state, the detection unit detects the wafer, and the calculation unit enters the working state to calculate the thickness of the wafer, as shown in the attached diagram. Figure 2 As shown in (a), time t1 is the time when the signal begins to be blocked by the wafer, time t2 is the time when the signal ends to be blocked by the wafer, and the duration of the signal being blocked by the wafer is t2-t1.

[0049] State 2: The signal emitted by the signal transmitting module is transmitted to the signal receiving module through the gap between adjacent wafers. The signal receiving module receives the signal. In this state, the detection unit does not detect a wafer, as shown in the attached diagram. Figure 2 As shown in (b), time t2 is the time when the signal receiving module starts to receive the signal, time t3 is the time when the signal starts to be blocked by the wafer, and the time when the signal receiving module receives the signal is t3-t2.

[0050] In this state, the detection unit transmits the time information t2 and t3 to the calculation unit. The calculation unit compares the magnitude of t3-t2 with Δt based on the preset time difference Δt to determine whether the wafer position is reasonable. When t3-t2 = Δt, it can be determined that the spacing between wafers is set reasonably and that there are no missing wafers, tilted angles, or other phenomena.

[0051] When t3-t2>Δt, it can be determined that the wafer pitch is too large or the wafer has an angular tilt phenomenon.

[0052] When t3-t2<Δt, it can be determined that the spacing between wafers is too small or that the wafers are tilted at an angle.

[0053] Δt is used to represent the time relationship between the reasonable gap value between adjacent wafers and the speed at which the displacement unit drives the detection unit. This converts the gap distance into the time difference between the signal received by the signal receiving module, making it easy to calculate. Different wafer containers have different requirements for wafer gap settings. Technicians can set the value of Δt according to the specifications of the container used to hold the wafers to ensure the accuracy of the detection results. For example, if the wafer container requires a placement gap of 10mm and the displacement unit drives the detection unit at a speed of 2mm / s, then the value of Δt is set to 5s.

[0054] For example, the medium carrying the detection unit is an optical signal sensor, that is, the detection function of the detection unit is realized through the optical signal sensor.

[0055] In one example of this embodiment, as shown in the appendix Figure 3As shown, the displacement unit includes a base 200 and a drive mechanism. The detection unit is mounted on the base 200. The base 200 drives the detection unit to move along the second direction. The drive mechanism is mounted on one side of the base 200 and drives the base 200 to move. The drive mechanism includes a rotating component 201 and a connecting component 202. The rotating component 201 is connected to the base 200 through the connecting component 202 to achieve transmission. For example, the rotating component 201 is driven by a motor to rotate. The rotating component 201 rotates relative to the connecting component 202. The connecting component 202 drives the base 200 to move relative to the rotating component 201, converting the rotation of the rotating component 201 into linear motion of the base 200 in the second direction. The lead L represents the distance the part fixed on the rotating component (i.e., the base and the detection unit on the base) moves linearly when the rotating component rotates one revolution. For example, if the lead L of the rotating component is 5mm, then when the rotating component rotates one revolution, the part mounted on the rotating component moves linearly 5mm.

[0056] For example, the rotating component 201 can also be directly connected to the base 200 to drive the base 200.

[0057] The analysis unit is set on the rotating part. The analysis unit is used to record the rotation data of the rotating part and transmit the data to the calculation unit, such as the number of rotations. For example, the medium carrying the analysis unit is a rotary encoder. The resolution of the rotary encoder is an important parameter. The resolution E is usually used to characterize the number of positions output by the rotary encoder when the spindle of the rotary encoder rotates one revolution. For example, if the resolution E of the rotary encoder is 1024, one revolution can be divided into 1024 parts.

[0058] In one example of this embodiment, as shown in the appendix Figure 4 As shown, assuming the base moves at a constant speed, let E represent the resolution of the rotary encoder, and t represent time. Figure 4 This represents the value of the rotary encoder's resolution E at time t, and the output resolution value at time t1 is E. t1 At time t2, the resolution output value is E. t2 Therefore, during the time interval t2-t1 when the detection unit passes through the wafer, the formula for calculating the number of revolutions N of the rotating component is:

[0059]

[0060] Based on the aforementioned number of revolutions N, the formula for calculating the wafer thickness T detected by the detection unit within the time interval t2-t1 is as follows:

[0061]

[0062] For example, the rotating component can be set as a screw, ball screw, trapezoidal screw, etc., as long as the replacement can achieve the function of this embodiment. The exemplary description in this embodiment should not be construed as a limitation on the rotating component.

[0063] For example, the motor of the drive mechanism is set as a DC motor or a servo motor.

[0064] In another example of this embodiment, the displacement unit is also equipped with a laser rangefinder or a linear encoder, which can directly detect the displacement of the detection unit driven by the displacement unit. This provides strong intuitiveness and high accuracy. The laser rangefinder or linear encoder can work with the analysis unit to perform secondary verification of the detection results of the analysis unit and the calculation results of the calculation unit, ensuring the accuracy and reliability of the calculation results.

[0065] As attached Figure 5 As shown, the wafer thickness detection method in this embodiment includes the following steps:

[0066] S1. Preset the values ​​and calculation formulas for the lead L of the displacement element and the resolution E of the analysis element in the calculation unit.

[0067] S2. The signal transmitting module and the signal receiving module of the detection unit are respectively set on both sides of the wafer in the first direction;

[0068] S3. The displacement unit drives the detection unit to move along the second direction;

[0069] S4. The signal transmitting module sends a signal, and the signal receiving module receives the signal.

[0070] S5. When the signal receiving module fails to receive a signal, the calculation unit records the time t1 when the signal changes.

[0071] S6. When the signal receiving module receives the signal again, the calculation unit records the time t2 when the signal changes.

[0072] S7, The analysis unit will output the resolution value E corresponding to time t1. t1 Send to the computing unit;

[0073] S8, the analysis unit will output the resolution value E corresponding to time t2. t2 Send to the computing unit;

[0074] S9. The calculation unit calculates the thickness of the wafer according to the calculation formula.

[0075] In another example of this embodiment, the order of steps S1 and S2 can be changed, that is, S2 is performed first and S1 is performed later.

[0076] In another example of this embodiment, steps S3 and S4 can be performed simultaneously, or step S4 can be performed before step S3.

[0077] In another example of this embodiment, steps S7 and S8 can be performed simultaneously, or S8 can be performed first and S7 can be performed later.

[0078] In another example of this embodiment, steps S5 and S7 can be performed simultaneously, steps S6 and S8 can be performed simultaneously, or steps S7 and S8 can be performed simultaneously. This embodiment does not limit the order of implementation by labeling the above steps.

[0079] As attached Figure 6 As shown, when performing thickness measurement on more than one wafer, the wafer thickness measurement method includes, in addition to S1 to S9 as described above, the following steps:

[0080] S1', Preset the value of time difference Δt on the calculation unit;

[0081] S2' When the signal receiving module changes from a state where it can receive signals to a state where it cannot receive signals, it sends time data to the analysis unit and the calculation unit, and the calculation unit records the time t3.

[0082] S3', Calculate the numerical values ​​of Δt and t3-t2.

[0083] In step S3' above, if Δt > t3 - t2, it indicates that the gap between wafers is too small or the wafers are placed at an angle, and the calculation unit records the corresponding position; if Δt = t3 - t2, it indicates that the gap between wafers meets the requirements; if Δt < t3 - t2, it indicates that the gap between wafers is too large, or a wafer is missing, or the wafers are placed at an angle, and the calculation unit records the corresponding position.

[0084] For example, the computing unit is connected to a display screen, which displays the status and thickness of the wafer.

[0085] For example, the computing unit can determine the number of wafers by calculating the number of times the signal changes in the signal receiving module.

[0086] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A wafer inspection system, wherein the central axis of the wafer is arranged parallel to a second direction, characterized in that, include: The detection unit includes a signal transmitting module and a signal receiving module respectively disposed on both sides of the wafer in a first direction. The signal transmitting module emits a signal, and the signal receiving module receives the signal from the signal transmitting module. The detection unit transmits the signal information to the computing unit. The displacement unit drives the detection unit to move along a second direction. The displacement unit includes a driving mechanism, which includes a rotating component. The displacement unit also includes a base. The detection unit is disposed on the base. The driving mechanism drives the base to move along the second direction. The rotating component is connected to the base and rotates relative to the base. The rotational motion of the rotating component is converted into linear motion of the base. An analysis unit is electrically connected to the displacement unit, and the analysis unit records the data information of the displacement unit and transmits the data information to the calculation unit; A calculation unit that collects data from the detection unit and the analysis unit and calculates the wafer thickness; The formula for calculating the thickness of the wafer is: In the formula: T represents the wafer thickness, L represents the linear displacement of the detection unit caused by the base during one revolution of the rotating component, N represents the number of revolutions of the rotating component, and E represents the resolution of the rotary encoder of the rotating component. This represents the resolution output value of the t1 time analysis unit. The resolution output value of the t2 time analysis unit is t1 time, which is the time when the signal emitted by the signal emission module begins to be blocked by the wafer, and the time when the signal emitted by the signal emission module ends to be blocked by the wafer.

2. The wafer inspection system according to claim 1, characterized in that: The analysis unit is mounted on the rotating component, and the analysis unit records the rotation data of the rotating component and transmits the rotation data to the calculation unit.

3. The wafer inspection system according to claim 1, characterized in that: The rotating component is configured as a screw, ball screw, or trapezoidal lead screw.

4. The wafer inspection system according to claim 1, characterized in that: The analysis unit is configured as a rotary encoder.

5. The wafer inspection system according to claim 1, characterized in that: The displacement unit is equipped with a laser rangefinder or a linear encoder, which detects the displacement of the displacement unit.

6. A wafer inspection method, comprising the wafer inspection system according to any one of claims 1 to 5, comprising the following steps: S1. Preset the values ​​and calculation formulas for the lead L of the displacement element and the resolution E of the analysis element in the calculation unit. S2. The signal transmitting module and the signal receiving module of the detection unit are respectively set on both sides of the wafer in the first direction; S3. The displacement unit drives the detection unit to move along the second direction; S4. The signal transmitting module sends a signal, and the signal receiving module receives the signal. S5. When the signal receiving module fails to receive a signal, the calculation unit records the time t1 when the signal changes. S6. When the signal receiving module receives the signal again, the calculation unit records the time t2 when the signal changes. S7, The analysis unit will output the resolution value corresponding to time t1. Send to the computing unit; S8, the analysis unit will output the resolution value corresponding to time t2. Send to the computing unit; S9. The calculation unit calculates the thickness of the wafer according to the calculation formula.

7. The wafer inspection method according to claim 6, characterized in that, It also includes the following steps: S1', Preset time difference on the computing unit The value; S2' When the signal receiving module changes from the state of receiving signals to the state of being unable to receive signals, it sends time data to the analysis unit and the calculation unit, and the calculation unit records the time t3; S3' Comparison of Computational Units The magnitude of t3-t2, if >t3-t2 indicates that the gap between wafers is too small, or the wafers are placed at an angle; the calculation unit records the corresponding position. =t3-t2, indicating that the gap between wafers meets the requirements; if <t3-t2 indicates that the gap between wafers is too large, or a wafer is missing, or a wafer is placed at an angle. The calculation unit records the corresponding position.

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