In-situ wireless detection device for wafer temperature

Abstract

The application relates to an in-situ wireless wafer temperature detection device, which is in a three-layer structure of an upper wafer, an in-situ wireless detection circuit and a lower wafer. The detection circuit adopts a flexible circuit board process, a gap between the upper and lower wafers and the detection circuit board is filled with a filling material and is flattened, and the edges of the upper and lower wafers are sealed with insulating materials, so that the flexible circuit board in the middle layer is insulated from the cavity environment. The wireless detection circuit comprises a temperature sensing module, a signal gating module, a data acquisition and processing module, a data storage module, a data wireless transmission module, a wireless charging module, a clock module and a battery module. The in-situ wireless detection device can pass through the same process steps as normal wafer processing, accurately measure and record the temperature change of the wafer surface in the reaction cavity during the process, and is an important system calibration tool and an auxiliary tool for parameter optimization in the process of semiconductor equipment research and development and integrated circuit manufacturing.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of integrated circuit manufacturing, and particularly relates to an in-situ wireless detection device for wafer temperature. BACKGROUND

[0002] In the process of integrated circuit manufacturing, the smaller the feature size of the device, the higher the control precision of temperature in the process. A slight deviation of the temperature on the wafer or a temperature non-uniformity of more than 1% in the cavity of the process equipment can affect the concentration distribution of the doping in the silicon device or the variation of the channel threshold voltage, thereby directly affecting the yield of the final product chip. In order to achieve high-precision control of temperature and temperature field distribution, accurate temperature distribution detection and real-time acquisition are required for the interior of the semiconductor equipment in most process links (such as PECVD, uniform glue development, lithography, etching, photoresist ashing, ion implantation, and cleaning). The in-situ wafer temperature detection technology in integrated circuit manufacturing thus develops. The in-situ wafer sensor technology refers to a detection device that undergoes the same process steps as the wafer processing to obtain accurate measurement of specific physical quantities in the reaction cavity, and is an important auxiliary tool for system calibration and parameter optimization in the development of semiconductor equipment and the process of integrated circuit manufacturing. At present, the existing patent described wafer temperature detection device is a wired device, that is, the temperature sensor on the wafer must be connected to the outside through a lead wire. However, most of the process equipment for semiconductor manufacturing is a closed cavity, and the lead wire end needs special treatment for the process chamber, which brings difficulty to actual operation. At the same time, due to the existence of the lead wire, the cavity cannot be completely sealed, thereby deviating from the temperature distribution of the actual process conditions. SUMMARY

[0003] The present application aims to provide an in-situ wireless detection device for wafer temperature, which does not need to connect the detection circuit to the outside through an interface lead wire, and the upper and lower circuits are sealed and packaged by two wafers. In the detection process, the device undergoes the same processing steps as the wafer without special treatment for the process equipment cavity, and can record the temperature data of the wafer at each place in the process, thereby providing a reference for the development of semiconductor equipment and the optimization of process parameters for integrated circuit manufacturing.

[0004] The wafer temperature in-situ wireless detection device has a "sandwich" structure, i.e., an upper wafer, an in-situ wireless detection main circuit, and a lower wafer. The wireless detection main circuit is made by using a flexible circuit process (FPC) to have a thin thickness. The space between the upper and lower wafers and the detection circuit board is filled with a filling material, and after filling, the flatness of the wafer is made to meet the requirements of the integrated circuit equipment machine through a flattening step. The edges of the upper and lower wafers are sealed with an insulating material to isolate the flexible circuit board in the middle from the cavity environment, thereby ensuring that the in-situ measurement circuit still works normally in a relatively harsh cavity environment (such as ion implantation process and plasma etching process).

[0005] The in-situ wireless detection circuit in the device specifically includes a temperature sensing module, a signal gating module, a data acquisition and processing module, a data storage module, a data wireless transmission module, a wireless charging module, a clock module, and a battery module. The technical scheme adopted is as follows:

[0006] The temperature sensing module accurately measures the temperature distribution of the wafer by using temperature sensors arranged radially from the center to the periphery. The temperature sensors use thermistors or thermocouples to convert temperature changes into electrical analog signals. The temperature-related analog signals are connected to the channel gating module through interconnecting lines.

[0007] The signal gating module is mainly composed of a multi-channel selection switch circuit and is responsible for collecting data of temperature sensors of all channels. The data acquisition and processing module controls whether each channel is in a gating state.

[0008] The data acquisition and processing module mainly uses a central processor. The central processor is responsible for controlling the channel gating logic of the signal gating module, the AD-digital signal conversion, and the timing logic of data storage. In the channel gating logic, the central processor sets parameters such as collection interval, channel conduction sequence, and collection duration. In the AD conversion circuit, the data of the selected temperature sensor is an accurate analog voltage quantity proportional to the absolute temperature. After comparison with the internal reference voltage in the processor, the data is input into a precise digital regulator to convert it into a digital voltage quantity with effective precision, thereby completing the AD-digital conversion function. The temperature data storage function is realized by the data read / write between the processor and the storage medium (master-slave device) through the peripheral interface of the processor.

[0009] The data storage module is responsible for storing temperature data during the entire test process and providing an interface for the central processor to access. The stored process data is sent to the host computer through the wireless transmission module after the detection is completed.

[0010] The data wireless transmission module realizes data transmission between the master and slave devices without external interfaces and wires through wireless communication technology.

[0011] The clock module forms a clock signal through a crystal oscillator and an oscillation circuit, and provides a clock signal for a timing logic of the central processing unit.

[0012] The battery module is powered by a lithium battery. Since the temperature measurement circuit is completely sealed by the upper and lower wafers and the filling material, the circuit itself has no electrical connection with the outside world, and the battery module is charged by the wireless charging module.

[0013] The wireless charging module adopts a non-contact electromagnetic induction wireless charging technology. The wireless charging transmitter sends wireless waves, and the wireless charging receiver converts the wireless waves sent by the wireless charging transmitter into electric energy through an electromagnetic coupling coil to charge the battery module in the temperature measurement circuit board, ensuring the supply of electric energy during the entire measurement process after the device enters the equipment cavity without external power lines.

[0014] The in-situ wireless detection device for wafer temperature is composed of the above-mentioned main functional modules and is processed into a flexible circuit board (FPC). The flexible circuit board is a printed circuit board with the characteristics of thin thickness and good bending property, which is made of polyimide or polyester film as the base material. The flexible circuit board itself has the characteristic of thin thickness, and further adopts wafer thinning technology to make the upper and lower wafers and the temperature detection circuit board integrally adhere, and the thickness of the overall device is close to the thickness range of a single normal wafer.

[0015] The technical effects and advantages of the present application mainly include:

[0016] 1. The present application adopts a "sandwich" structure of upper and lower wafer packaging and thin film circuit in the middle. The entire device has the same diameter as a normal wafer. By adopting a thin film circuit manufacturing process and upper and lower wafer thinning process, the thickness is close to that of a normal wafer and the device enters the machine without causing machine alarm after wafer flattening process.

[0017] 2. The present application is an in-situ detection technology. The device can enter the reaction cavity directly to collect the temperature distribution data on the wafer surface during the process through the same process steps as the wafer.

[0018] 3. The device of the present application adopts wireless charging and wireless data transmission technology. The device itself has no electrical connection with the outside world during the measurement process, and no special treatment is required for the process chamber. DETAILED DESCRIPTION

[0019] In order to more clearly illustrate the technical solutions or embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the specific implementation details of the present application described in the drawings can also be obtained by those skilled in the art without creative labor.

[0020] Figure 1 is the overall structure profile of the wafer temperature in-situ wireless detection device.

[0021] Figure 2 is the system block diagram of the wafer temperature in-situ wireless detection main circuit.

[0022] Figure 3 is the temperature in-situ sensor placement and connection schematic diagram. DETAILED DESCRIPTION

[0023] In order to better express the technical solutions of the present application, further description will be made in combination with the drawings.

[0024] The structure profile of the wafer temperature in-situ wireless detection device is shown in Figure 1 The flexible circuit board is integrally attached to the upper and lower wafers to form a "sandwich" structure. The in-situ wireless detection main circuit is made by flexible circuit technology (Flexible Printed Circuit, FPC). The circuit board is circular, and the circuit board is attached to the upper wafer (101) and the lower wafer (102), and the diameter of the circuit board is smaller than the wafer. Since the thickness of the chip (103) and the temperature sensor (103) on the board is greater than the thickness of the flexible circuit board (104), when the circuit board is attached to the wafer, a gap will appear between the wafer and the circuit board. The gap is filled with a filling material (105), and after filling, it is processed by a leveling step. The outer edge of the upper and lower wafers is sealed with an insulating material (106) to protect the internal temperature measurement circuit.

[0025] Further, since the chip on the circuit board is higher than the flexible circuit board, a gap will appear between the upper and lower wafers and the circuit board. The filling material in the gap is a high-temperature-resistant, low-volatile, and low-viscosity adhesive.

[0026] Further, after the flexible circuit board is attached to the upper and lower wafers and filled with the adhesive, a wafer leveling step is performed.

[0027] Further, since the detection circuit board is circular and has a diameter smaller than the wafer diameter, the outer edge of the upper and lower wafers is sealed with an insulating material, and the wafer is leveled.

[0028] Further, the circuit board is made by the flexible circuit technology, which can greatly reduce the thickness, and by selecting appropriate devices, the overall circuit thickness can be thinner than the normal wafer thickness.

[0029] The system architecture of the in-situ wireless detection circuit is shown in Figure 2As shown, in the data acquisition stage, the temperature sensing module transmits the measured process data to the processor via signal gating. After AD-DAC conversion and signal processing operations by the processor, the processed data is stored in the storage module. After the detection is completed, the measuring device exits the equipment cavity and data reading can be performed. In the data reading stage, the host computer sends a command to the processor through wireless communication. The processor completes data reading between the master and slave devices through the peripheral communication interface and sends the data back to the host computer through wireless communication.

[0030] Preferably, the temperature sensors in the temperature sensing module can use thermistors or thermocouples, which are placed in a radial distribution from the center to the periphery. Figure 3 For example, 32 thermistors (301) are placed as temperature sensors.

[0031] Preferably, in the data acquisition and processing module, the multi-channel selection switch can be a four-channel bidirectional selection switch. Figure 3 For example, 32 temperature sensors (301) are connected with 8 four-channel bidirectional selection switches (302) and 1 central processor (303).

[0032] Preferably, the central processor (303) can be implemented by FPGA or MCU, for example, considering the rich interface resources, an STM32 series chip can be selected for implementation.

[0033] Preferably, AD-DAC signal conversion can be completed inside the processor to convert the temperature analog signal into a digital signal, which facilitates subsequent signal processing, data reading and writing, and data communication.

[0034] Preferably, the storage medium of the data storage module can be implemented by a Flash chip, and the data reading and writing operations between the processor (master device) and the Flash (slave device) can be mainly realized through the SPI (Serial Peripheral Interface) serial peripheral communication interface of the processor.

[0035] Preferably, the data wireless transmission mainly has three technical approaches: Bluetooth, wifi, and ZigBee, which can be selected for implementation.

[0036] Preferably, a sheet-shaped lithium battery is used as the power supply device of the system. In the wireless charging module, the wireless charging transmitter sends wireless waves, which are converted into electric energy by the electromagnetic coupling coil through the wireless charging receiver, to charge the lithium battery of the temperature measuring circuit board, ensuring the power supply during the whole measurement process after the device enters the equipment cavity without the need for external charging wires.

[0037] The principles and implementation manners of the present application are described herein by using specific examples, and the above example descriptions and the specific numbers involved in the text are only to help understand the method of the present application and its core idea. It should be pointed out that, for ordinary skilled persons in the technical field, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. An in-situ wireless detection device for wafer temperature, characterized in that: The in-situ wireless detection circuit in the device specifically comprises a temperature sensing module, a signal gating module, a data acquisition and processing module, a data storage module, a data wireless transmission module, a wireless charging module, a clock module, and a battery module; the in-situ wireless detection device for wafer temperature is composed of the above-mentioned main functional modules and is processed into a flexible circuit board FPC; the flexible circuit board is a printed circuit board with thin thickness and good bending property, which is made of polyimide or polyester film as a base material; the flexible circuit board itself has the characteristic of thin thickness, and further wafer thinning technology is adopted to make the upper and lower wafers and the temperature detection circuit board integrally adhere, and the thickness of the overall device is close to the thickness range of a single normal wafer; the flexible circuit board and the upper and lower wafers are integrally adhered to form a sandwich structure; the in-situ wireless detection main circuit is made by the flexible circuit process; the flexible circuit board is circular, the flexible circuit board adheres to the upper wafer (101) and the lower wafer (102), and the diameter of the flexible circuit board is smaller than that of the upper and lower wafers; since the thicknesses of the chip (103) on the board and the temperature sensor are both greater than that of the flexible circuit board (104), when the flexible circuit board adheres to the upper and lower wafers, a gap will appear between the wafers and the circuit board, the gap is filled with a filling material (105), and after filling, a leveling step is performed; the outer edges of the upper and lower wafers are sealed with an insulating material (106) to protect the internal in-situ wireless detection circuit; The filling material in the gap is a high-temperature-resistant, low-volatile, and low-viscosity adhesive; The temperature sensing module accurately measures the temperature distribution of the wafer through temperature sensors arranged radially from the center to the periphery; the temperature sensor uses a thermistor or a thermocouple to convert temperature changes into an electrical analog signal, and the temperature-related analog signal is connected to the signal gating module through a circuit; The signal gating module is mainly composed of a multi-channel selection switch circuit, which is responsible for collecting temperature sensor data of all channels and is controlled by the data acquisition and processing module to determine whether each channel is in the gating state.

2. The apparatus of claim 1, wherein: The data acquisition and processing module mainly uses a central processing unit; the central processing unit is responsible for controlling the channel gating logic of the signal gating module, the AD digital-analog signal conversion, and the timing logic of data storage; in the channel gating logic, the central processing unit sets the collection interval, the channel conduction sequence, and the collection duration; in the AD conversion circuit, the data of the selected temperature sensor is an accurate analog voltage quantity proportional to the absolute temperature, which is compared with the internal reference voltage in the central processing unit and input into a precise digital regulator to convert into a digital voltage quantity with effective precision, thereby realizing the AD digital-analog conversion function; the temperature data storage is realized through the peripheral interface of the processor to read and write data between the processor and the storage medium.

3. The apparatus of claim 1, wherein: The data storage module is responsible for storing the temperature data during the entire test process and providing an interface for the central processing unit to access; The stored process data is sent to the upper computer through the wireless transmission module after the detection is completed.

4. The apparatus of claim 1, wherein: The battery module is powered by lithium batteries and uses non-contact electromagnetic induction wireless charging technology to supply power to the battery module; the in-situ wireless detection circuit is completely sealed by the upper and lower wafers and the filling material, and the circuit itself has no electrical connection with the outside world.

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