Wafer warping degree measuring system

Abstract

The invention provides a wafer warping degree measurement system, and the system comprises a laser which is used for transmitting detection laser; the beam splitter spacer is used for converting the detection laser into corresponding first laser and second laser; the reflecting mirror is used for correspondingly reflecting the first laser and the second laser to the surface of the wafer; the beam splitting element is arranged between the beam splitting spacer and the reflecting mirror; the at least two displacement sensors are mounted right above the light splitting element; wherein the first laser and the second laser returned from the surface of the wafer are reflected back to the light splitting element through the reflecting mirror, and the returned first laser and the returned second laser are correspondingly refracted into the displacement sensor through the light splitting element; and the controller collects target positions correspondingly generated by the returned first laser and the returned second laser in the displacement sensor in real time, and correspondingly calculates the warping degree corresponding to the wafer according to the target positions in real time. According to the invention, the warping degree of the wafer can be accurately calculated, and the working efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a wafer warpage measurement system. Background Art

[0002] With the advancement of science and technology and the development of the times, semiconductor technology has also developed rapidly. Among them, wafers are an important semiconductor component used to further prepare various semiconductor devices.

[0003] Among them, existing wafers may have a certain degree of warping during the growth and deposition process, and the size of the warping will directly affect the performance of the prepared chip. Therefore, during the production process, it is necessary to measure the corresponding warping of the wafer surface in real time to ensure the yield of the product.

[0004] Furthermore, in the process of measuring the warpage of the wafer surface, most of the existing technologies use a laser displacement sensor to perform a global scan of the wafer surface, or use a high-precision camera to perform object morphology detection on the wafer. However, the above measurement methods all require that the wafer be placed on a detection platform and remain motionless, and at the same time, a laser rangefinder or camera needs to be moved to measure the wafer. However, certain deviations may occur in the process of moving the laser rangefinder or camera, which will cause certain errors in the measurement results and correspondingly reduce work efficiency. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a wafer warpage measurement system to solve the problem that in the prior art, certain deviations may occur during the process of measuring wafer warpage, resulting in errors in the measurement results.

[0006] On the one hand, the embodiments of the present invention provide: A wafer warpage measurement system, wherein the system comprises: a curvature measurement probe and a controller, wherein the curvature measurement probe is installed above a growth furnace observation window, and the curvature measurement probe is electrically connected to the controller, and the curvature measurement probe comprises: A laser, used for emitting a detection laser; A beam splitter spacer is arranged opposite to the emission port of the laser and is used to convert the detection laser into a corresponding first laser and a second laser, wherein the first laser and the second laser are parallel to each other; A reflector, used to reflect the first laser and the second laser to the surface of the wafer respectively; A beam splitting element is installed between the beam splitting spacer and the reflector; At least two displacement sensors are installed directly above the light splitting element; Among them, the first laser and the second laser returned from the surface of the wafer are reflected back to the spectroscopic element through the reflector, and the returned first laser and the second laser are correspondingly refracted to the inside of the displacement sensor by the spectroscopic element, and the target positions generated by the returned first laser and the second laser inside the displacement sensor are collected in real time by the controller, and the warpage corresponding to the wafer is calculated in real time according to the target position, and the target position is unique.

[0007] The beneficial effect of the present invention is that by arranging the laser, beam splitter spacer, reflector, beam splitter element and displacement sensor at specific positions respectively, a specific detection system can be formed accordingly. In actual application, the laser only needs to emit the corresponding laser to immediately reach the surface of the wafer. Furthermore, the laser returned from the wafer surface can reach the displacement sensor accordingly and form a corresponding light spot inside the displacement sensor. Therefore, the present application can directly determine whether the wafer surface has defects according to the position of the light spot and calculate the corresponding warpage, thereby avoiding errors and improving work efficiency.

[0008] Furthermore, when the controller detects in real time that the returned first laser and the second laser both irradiate the center position of the displacement sensor, the warpage of the wafer calculated in real time is 0, and the spot interval between the returned first laser and the second laser is the same as the beam spacing of the beam splitter spacer, and the warpage includes a specific numerical value.

[0009] Furthermore, when the controller detects in real time that the returned first laser and the second laser do not irradiate the center position of the displacement sensor, and the warpage of the wafer calculated in real time is a negative value, it is determined that the surface of the wafer has a protrusion, and the spot interval between the returned first laser and the second laser is greater than the beam spacing of the beam splitter spacer, wherein each displacement sensor corresponds to a laser.

[0010] Furthermore, when the controller detects in real time that the returned first laser and the second laser do not irradiate the center position of the displacement sensor, and the warpage of the wafer calculated in real time is a positive value, it is correspondingly determined that there is a depression on the surface of the wafer, and the spot interval between the returned first laser and the second laser is smaller than the beam spacing of the beam spacer, and the spot interval and the beam spacing both have corresponding values.

[0011] Furthermore, the controller calculates the warpage corresponding to the wafer in real time using the following algorithm:

[0012] Wherein, k represents the warpage, R represents the surface curvature of the wafer, D0 represents the spot spacing between two lasers corresponding to when the measuring probe measures a wafer with a curvature of 0, D represents the real-time spot spacing between the two lasers, and H represents the calibration parameter.

[0013] Furthermore, the interval between at least two of the displacement sensors is equal to the beam splitting spacing of the beam splitting spacer, and the displacement sensor is configured as a two-dimensional PSD displacement sensor.

[0014] Furthermore, the wavelength of the detection laser emitted by the laser is 405 nanometers, 520 nanometers, or 650 nanometers, and the bandwidth of the laser is 10 nanometers.

[0015] Furthermore, the beam splitter element is configured as a beam splitter, and the beam splitter is arranged opposite to an exit port of the beam splitter spacer.

[0016] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of an optical path of a wafer warpage measurement system provided by an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a wafer warpage measurement system provided in one embodiment of the present invention.

[0018] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0020] It should be noted that when an element is referred to as being "fixedly mounted" on another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0022] See also Figure 1 , shown is a wafer warpage measurement system provided in an embodiment of the present invention. The wafer warpage measurement system provided in this embodiment can quickly and accurately detect the warpage of each wafer, thereby correspondingly improving work efficiency.

[0023] Specifically, this embodiment provides: A wafer warpage measurement system, the system comprising: a curvature measurement probe and a controller, the curvature measurement probe is installed above a growth furnace observation window, and the curvature measurement probe is electrically connected to the controller, the curvature measurement probe comprises: A laser 10, used for emitting a detection laser; A beam splitter spacer 20 is arranged opposite to the emission port of the laser 10, and is used to convert the detection laser into a corresponding first laser and a second laser, wherein the first laser and the second laser are parallel to each other; A reflector 40, used to reflect the first laser and the second laser to the surface of the wafer respectively; The beam splitting element 30 is installed between the beam splitting spacer 20 and the reflector 40; At least two displacement sensors 50 are installed directly above the light splitting element 30; Among them, the first laser and the second laser returned from the surface of the wafer are reflected back to the spectroscopic element 30 through the reflector 40, and the returned first laser and the second laser are refracted correspondingly to the inside of the displacement sensor 50 through the spectroscopic element 30, and the target position generated by the returned first laser and the second laser inside the displacement sensor 50 is collected in real time by the controller, and the warpage corresponding to the wafer is calculated in real time according to the target position, and the target position is unique.

[0024] Specifically, in this embodiment, it should be noted that in order to quickly and accurately measure the warpage of each wafer, it is necessary to quickly and accurately obtain information about the surface of the wafer, that is, to quickly and accurately determine whether the surface of the wafer has defects. Based on this, the present invention provides a special measurement system, which only needs to use a laser 10, a beam splitter spacer 20, a reflector 40, a beam splitter element 30 and a displacement sensor 50. Specifically, Figure 1As shown, the above-mentioned components are arranged in a corresponding manner according to a specific positional relationship so as to quickly obtain information about the surface of the wafer. Figure 2 As shown, multiple wafers are placed on a turntable and rotated around the axis accordingly. As the turntable and the graphite disk are continuously heated, a thin film is slowly deposited on the surface of the wafer, which may cause the surface of the wafer to warp. Based on this, it is necessary to perform corresponding warpage measurement on each wafer. Preferably, in the actual application process, the curvature measurement probe provided by the present invention is specifically installed above the observation window of the growth furnace, and the curvature measurement probe provided by the present invention can be applied to growth furnaces with small-sized observation windows, as well as growth furnaces with fast and slow rotation speeds, and has a wide range of applications.

[0025] Furthermore, in the actual detection process, the corresponding detection laser is first emitted by the laser 10, and the detection laser can be directly emitted into the interior of the above-mentioned beam splitter spacer 20, and can further be divided into two by the beam splitter spacer 20 to form the corresponding first laser and second laser. Specifically, the spot size and brightness between the first laser and the second laser are the same. Based on this, after the current first laser and the second laser pass through the above-mentioned beam splitter element 30, they will be further reflected to the surface of the wafer through the above-mentioned reflector 40. On this basis, the current first laser and the second laser will be further reflected on the surface of the current wafer, and can further return to the above-mentioned beam splitter element 30 along the original path. Based on this, it should be pointed out that the beam splitter element 30 can use its characteristics to immediately refract the current first laser and the second laser to the interior of the above-mentioned displacement sensor 50, and finally detect the position of the light spot in real time through the displacement sensor 50, so as to further calculate the warpage of the wafer surface according to the position of the light spot. In addition, it should be pointed out that the turntable provided by the present invention is mainly made of graphite, and the detection laser emitted by the above-mentioned laser 10 will not be reflected on the surface of the turntable, and the laser irradiated on the surface of the wafer will reflect part of the light back to the inside of the above-mentioned displacement sensor 50, so that the turntable and the wafer can be distinguished by the difference in signal intensity corresponding to the reflection of the laser on different materials, thereby improving the detection efficiency accordingly.

[0026] Furthermore, the main working principle of the wafer warpage measurement system provided by the present invention is: two parallel laser beams with known intervals are correspondingly produced by the laser 10 and the beam splitter spacer 20, wherein the spot size and brightness of the two parallel laser beams are the same, based on this, the two laser beams are further irradiated on the surface of the wafer and reflected on the surface of the wafer, so that they can eventually return to the inside of the displacement sensor 50, based on this, by real-time detection of the position of the spot formed by the laser inside the displacement sensor 50, the warpage of each wafer surface can be finally calculated, thereby correspondingly improving work efficiency.

[0027] Furthermore, when the controller detects in real time that the returned first laser and the second laser both irradiate the center position of the displacement sensor 50, the warpage of the wafer calculated in real time is 0, and the spot interval between the returned first laser and the second laser is the same as the beam spacing of the beam splitter spacer, and the warpage includes a specific numerical value.

[0028] Furthermore, when the controller detects in real time that the returned first laser and the second laser are not irradiated at the center position of the displacement sensor 50, and the warpage of the wafer calculated in real time is a negative value, it is determined that the surface of the wafer has a protrusion, and the spot interval between the returned first laser and the second laser is greater than the beam spacing of the beam spacer 20, wherein each displacement sensor 50 corresponds to a laser.

[0029] Furthermore, when the controller detects in real time that the returned first laser and the second laser do not irradiate the center position of the displacement sensor 50, and the warpage of the wafer calculated in real time is a positive value, it is correspondingly determined that the surface of the wafer has a depression, and the spot interval between the returned first laser and the second laser is smaller than the beam spacing of the beam spacer 20, and the spot interval and the beam spacing both have corresponding values.

[0030] Furthermore, the controller calculates the warpage corresponding to the wafer in real time using the following algorithm:

[0031] Wherein, k represents the warpage, R represents the surface curvature of the wafer, D0 represents the spot spacing between two lasers corresponding to when the measuring probe measures a wafer with a curvature of 0, D represents the real-time spot spacing between the two lasers, and H represents the calibration parameter.

[0032] Furthermore, the interval between at least two of the displacement sensors 50 is equal to the beam splitting interval of the beam splitting spacer 20, and the displacement sensor 50 is configured as a two-dimensional PSD displacement sensor.

[0033] Furthermore, the wavelength of the detection laser emitted by the laser 10 is 405 nanometers, 520 nanometers, or 650 nanometers, and the bandwidth of the laser 10 is 10 nanometers.

[0034] Furthermore, the beam splitter element 30 is configured as a beam splitter, and the beam splitter is disposed opposite to an exit port of the beam splitting spacer 20 .

[0035] In summary, the wafer warpage measurement system provided by the above embodiments of the present invention can quickly and accurately calculate the warpage of each wafer, thereby correspondingly improving work efficiency.

[0036] It should be noted that the above modules can be functional modules or program modules, and can be implemented by software or hardware. For modules implemented by hardware, the above modules can be located in the same processor; or the above modules can be located in different processors in any combination.

[0037] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0038] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0039] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0040] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0041] The above-described embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A wafer warpage measurement system, characterized in that: The system includes: a curvature measurement probe and a controller, wherein the curvature measurement probe is installed above the observation window of the growth furnace, and the curvature measurement probe is electrically connected to the controller, and the curvature measurement probe includes: A laser, used for emitting a detection laser; A beam splitter spacer is arranged opposite to the emission port of the laser and is used to convert the detection laser into a corresponding first laser and a second laser, wherein the first laser and the second laser are parallel to each other; A reflector, used to reflect the first laser and the second laser to the surface of the wafer respectively; A beam splitting element is installed between the beam splitting spacer and the reflector; At least two displacement sensors are installed directly above the light splitting element; Among them, the first laser and the second laser returned from the surface of the wafer are reflected back to the spectroscopic element through the reflector, and the returned first laser and the second laser are correspondingly refracted to the inside of the displacement sensor by the spectroscopic element, and the target positions generated by the returned first laser and the second laser inside the displacement sensor are collected in real time by the controller, and the warpage corresponding to the wafer is calculated in real time according to the target position, and the target position is unique.

2. The wafer warpage measurement system according to claim 1, characterized in that: When the controller detects in real time that the returned first laser and the second laser both irradiate the center position of the displacement sensor, the warpage of the wafer calculated in real time is 0, and the spot interval between the returned first laser and the second laser is the same as the beam spacing of the beam splitter spacer, and the warpage contains a specific numerical value.

3. The wafer warpage measurement system according to claim 1, characterized in that: When the controller detects in real time that the returned first laser and the second laser do not irradiate the center position of the displacement sensor, and the warpage of the wafer calculated in real time is a negative value, it is determined that the surface of the wafer has a protrusion, and the spot interval between the returned first laser and the second laser is greater than the beam spacing of the beam splitter spacer, wherein each displacement sensor corresponds to a laser.

4. The wafer warpage measurement system according to claim 1, characterized in that: When the controller detects in real time that the returned first laser and the second laser do not irradiate the center position of the displacement sensor, and the warpage of the wafer calculated in real time is a positive value, it is correspondingly determined that there is a depression on the surface of the wafer, and the spot interval between the returned first laser and the second laser is smaller than the beam spacing of the beam spacer, and the spot interval and the beam spacing both have corresponding values.

5. The wafer warpage measurement system according to claim 1, characterized in that: The controller calculates the warpage corresponding to the wafer in real time using the following algorithm: Wherein, k represents the warpage, R represents the surface curvature of the wafer, D0 represents the spot spacing between two lasers corresponding to when the measuring probe measures a wafer with a curvature of 0, D represents the real-time spot spacing between the two lasers, and H represents the calibration parameter.

6. The wafer warpage measurement system according to claim 1, characterized in that: The interval between at least two of the displacement sensors is equal to the beam splitting pitch of the beam splitting spacer, and the displacement sensor is configured as a two-dimensional PSD displacement sensor.

7. The wafer warpage measurement system according to claim 1, characterized in that: The wavelength of the detection laser emitted by the laser is 405 nanometers, 520 nanometers or 650 nanometers, and the bandwidth of the laser is 10 nanometers.

8. The wafer warpage measurement system according to claim 1, characterized in that: The light splitting element is configured as a beam splitter, and the beam splitter is arranged opposite to the exit port of the beam splitting spacer.

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