JPS63161637A - Recognizer for position of semiconductor wafer - Google Patents

Abstract

PURPOSE:To release an operator from simple labor by automatically recognizing the quantity of positional displacement consisting of the x and y directions and thetatransfer components of respective semiconductor wafer and correcting positions so that mutual semiconductor wafers relatively coincide, using either one of wafers as a reference. CONSTITUTION:A flat surface 4 is formed to a support section (a chuck) 3 fixing a semiconductor wafer 2 for joining, and a scattering plate 5 is mounted adjacent to the flat surface 4 besides the arrangement of a stage section 8 moving the support section 3. A light source 7 irradiating the scattering plate 5 and a photoconductive conversion mechanism image-sensing the light source 7 and capable of inputting the silhouette of the semiconductor wafer 2 are prepared, and control mechanisms 10, 10' connected to the photoconductive conversion mechanism and a measuring section 11 incorporating a picture memory 15 to which outputs from the control mechanisms are input are fitted. A bus 12 is connected to the measuring section 11, an information storage section 14 receiving and transmitting a signal from the measuring section 11 and an arithmetic operation section 13 are set up through the bus 12, a power section transmitting the result of arithmetic operation is connected to the stage 8, and a controller 19 is arranged between the information storage section 14 and the power section. Accordingly, productivity is improved.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is applicable to forming a single semiconductor wafer by closely bonding two semiconductor wafers (hereinafter referred to as bonding technology). The present invention relates to a semiconductor wafer recognition device.

(Conventional technology) Conventionally, the collector junction of diodes, bipolar transistors, etc., and the drain junction of double diffusion MO5FET, etc. have been connected to P.
The N-junction is used as a reverse bias state, and in order to reduce the series resistance that occurs at that time, a stacked structure with an N-semiconductor substrate with an N-acoustic conductor substrate as the base is used, and the N-semiconductor substrate is A semiconductor element is provided by introducing conductive type impurities, and the thickness of the N-tone conductor substrate is increased to improve the withstand voltage and mechanical strength. Moreover, by ensuring a sufficient distance between the bottom of the PN junction obtained by introducing this impurity and the N sound conductor substrate, the 'Research Dhr.
It is common to prevent the breakdown phenomenon caused by "rough". The so-called epitaxial growth method is widely used to achieve this layered structure, but if there is a difference in concentration of impurities contained in the underlying semiconductor substrate. The reality is that due to auto-diffusion of impurities, it is not possible to achieve strict concentration control beyond the boundaries.

However, there are differences in the concentration of impurities contained, and bonding techniques have been developed to integrate these semiconductor substrates regardless of the difference in conductivity type.

That is, this is a technique for obtaining a composite semiconductor substrate that has sufficient mechanical strength and can be handled as a single semiconductor substrate by closely contacting the surface of a semiconductor substrate that is somewhat moist. It is assumed that crystals that are somewhat different from the original (bulk) crystals are formed on this contact surface.

A functional element that does not act as a thermal or electrical barrier and utilizes a PN junction provided here can sufficiently exhibit the necessary electrical characteristics, and can also be applied to silicon oxide layers and polycrystalline silicon layers.

In order to bring the semiconductor wafers into close contact with each other, it is necessary to align them, so the image is captured using an industrial TV camera and displayed on a monitor to make it visible. Measure the amount of movement and tilt component. This result is supplied to the X-Y-e stage on which the semiconductor wafer is placed, and positioning is performed by the operator's visual judgment and manual operation.

When imaging with this industrial TV camera, a ring irradiation device or a light bulb located above the semiconductor wafer is used.

(Problem to be Solved by the Invention) In such a manual alignment method, the amount of parallel movement and the amount of tilt, which are necessary position correction components, are manually determined and then the corresponding correction work is performed. As a result, workers are forced to perform simple tasks for long periods of time, causing eye strain and reducing productivity. In addition, the proficiency level of workers has a large impact on productivity, which becomes a problem in workplaces aiming to secure a certain index, and the difficulty of increasing the frequency of product quality loss is unavoidable.

As mentioned above, when using an industrial TV camera, a method was adopted in which the light source was illuminated from above the mirror semiconductor wafer, so the light source was reflected on the mirror surface of the semiconductor wafer, and the important semiconductor wafer was Only part of the light can be illuminated, which poses a problem for image processing.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel semiconductor wafer position recognition device that eliminates the above-mentioned difficulties.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve this object, the present invention improves the illumination means and automatically recognizes the position of the semiconductor wafer for bonding.

A support part (chuck) for fixing a semiconductor wafer for bonding is provided with a flat surface, and in addition to disposing a stage part that makes this support part movable, a scattering plate is installed adjacently along this flat surface. A control mechanism that prepares and connects a light source that illuminates the scattering plate and a photoconductive conversion mechanism that images the light source and makes it possible to input the silhouette of the semiconductor wafer;
A measuring section is provided that includes a built-in image memory for inputting this output. A bus is connected to the measurement section, and an information storage section and a calculation section are provided for receiving and receiving signals from the measurement section via the bus, and a power section for transmitting calculation results is connected to the stage,
A controller is disposed between the information storage section and the power section.

(Function) To bring two semiconductor wafers into close contact, the semiconductor wafers to be bonded are placed on the support part that fixes each semiconductor wafer, and the semiconductor wafers to be bonded are placed on the support part provided at the end of the arm that can rotate 180 degrees. After correcting the position of the semiconductor wafer placed on the movable stage section,
° The rotating semiconductor wafer to be bonded is brought into close contact with the semiconductor wafer to be bonded to carry out the bonding process.

One way to correct the positions of these two semiconductor wafers is to accurately calculate the positional coordinates of each, find the amount of deviation from the center of the ITV camera, and calculate the difference by canceling out this amount of deviation. It is estimated that the required time will increase because conversion is required.

In contrast, in the present invention, after calculating the information necessary for correction based on the amount of deviation of the semiconductor wafer for mounting from the center of the ITV camera, the information, that is, the coordinate values of the semiconductor wafer to be bonded (transferred) is used for bonding (position correction). This method aims to improve productivity by adopting a method of calculating a correction value by calculating the difference by converting it into the coordinate value of the semiconductor wafer (adjusting the position by).

Specifically, the semiconductor wafers to be bonded and the semiconductor wafers to be bonded are imaged by an ITV camera that uses photoconductive conversion means, and this image is converted into a video signal by a control unit and sent to a measurement unit with built-in image memory. . This measurement unit is connected to a calculation unit and an information storage unit via a bus, and this is connected to a machine controller, a motor driver, and a power source, and this power source is further connected to the stage on which the semiconductor wafer support is mounted. do. In addition, in this device, a scattering plate is installed along the bottom of the support part, which has a flat surface, and the attached light source is imaged by an ITV camera, and the silhouette of the semiconductor wafer to be bonded is captured as an image, and the image is converted into 1-inversion and binary data. By using a screen where the center, that is, the position corresponding to the semiconductor wafer, is black and the surrounding area is white, the area selectively provided around this circumference, which is necessary for various calculations, has a clear contrast. This is extremely convenient as it can reduce errors.

The priority of such a system is given to the machine controller, and in response to its instructions, the arithmetic unit performs image processing on the image memory built into the measurement unit, which is processed by the parallel interface (PIO) installed in the information storage unit. This is based on the set image processing conditions, and the binarized signal is stored in this image memory as well as in the memory provided in the information storage unit. On the other hand, in order to cope with changes in resolution caused by differences in the diameter of semiconductor wafers, setting conditions are determined by this PIO, and the display provided in the system is adjusted to match the zoom installed on the TV camera by the operator.

Furthermore, the image memory built in the measurement section is scanned in response to a command from the calculation section to determine the center position coordinates of the semiconductor wafer, the position coordinates of the orientation flat section, and the inclination, and these are stored in the memory of the information storage section. Next, one of the coordinate values calculated for the two semiconductor wafers is converted to the other coordinate value, the difference is determined, and the amount of relative position correction is determined, and then the semiconductor wafer is placed via a machine controller etc. move the stage section. After completing the positional correction in this way, the two wafers are brought into close contact to complete the bonding.

(Example) An example according to the present invention will be described in detail with reference to FIGS. 1 to 14.

As mentioned above, a mirror surface is formed on the surface of the semiconductor wafer subjected to the bonding process. To explain this process, the polycrystalline silicon layer, the Mide layer, and the surface of the silicon semiconductor wafer that make up the bonding surface are polished to reduce roughness. A mirror surface with a thickness of 500 Å or less is provided, and depending on the surface condition after the polishing process, oils and fats are removed by a pretreatment process using acids. Next, wash with clean water for a few minutes and then perform a dehydration process such as a spinner treatment at room temperature to remove excess moisture while leaving the moisture that is assumed to have been adsorbed on the mirror surface as it is. However, avoid heating and drying at temperatures above 100°C, where most of this adsorbed moisture will evaporate.

The semiconductor wafers that have undergone this treatment are placed in a clean atmosphere of class 1 or below, for example, and are closely bonded to each other without any foreign matter (dust) intervening between the mirror surfaces to form a composite semiconductor substrate. To increase this joint strength, 20
Heat treatment can be performed at a temperature of 0° C. or higher, preferably 1000° C. to 1200° C., and as the atmosphere, oxygen or a mixed atmosphere of both, in addition to the atmosphere, can be used in both the bonding step and the heating step.

By the way, in this bonding process, a polar group is obtained by washing the mirror surface with water, and the bonding caused by this polar group causes the original (
It is assumed that a composite semiconductor substrate can be obtained by forming a bonding layer having a composition different from that of +3ulk).

Now, in the semiconductor wafer position recognition device according to the present invention, the semiconductor wafer 2.2' to be bonded is placed on the support part 4 having a flat bottom surface 3 as shown in FIG. A scattering plate 5 is disposed along the line 3 and is locked to the stage part 8, and this state is shown in the block diagram of FIG. The semiconductor wafers 2, 2' have an orientation flat part 1.1'
In addition, the surface has a mirror finish as mentioned above,
A cover 6 is attached to the periphery of the scattering plate 5, and a light source 7, such as an incandescent light bulb, is installed near its free end. The scattering plate 5 is made of, for example, an aluminum plate and is treated with a silver satin finish so that the light emitted from the light source is scattered.

FIG. 3 shows a top view of FIG. 2, and the light source 7 is installed at a symmetrical position on the cover 6, and FIG. 4 shows an illumination equipment in which the arrangement of the light source, etc. is changed.

In this example, the light source 7 is directly embedded in the support portion 4, and the semiconductor wafer itself serves as the cover 6. In either case, the semiconductor wafer is uniformly exposed. The semiconductor wafer 2' is placed on a stage section 8 movable in the X, Y, and θ directions, and two industrial TV cameras 9, 9' equipped with a zoom mechanism are used to take images of the semiconductor wafer 2'.
The signal is sent to the control mechanism 10, 10', converted into a video signal, and then input to the needle measuring section 11.

This measurement unit 11 scans! ! It has a built-in image memo (not shown) having a size of 518 x 518, and is connected to the calculation unit 13 and the information storage unit 4 via the local CPU bus 12.
Signals are exchanged between these three departments.

The information storage section υ consists of a memory 15, a timer unit 16, a serial interface 17, and a parallel interface 18, each connected to an 8-bit CPU bus 12, and the serial interface 12 is equipped with a machine controller R5-232C (JIS standard product). Model number) 19
Connect to. The relative position correction amounts Δf, Δy, and Δθ of the semiconductor wafers 2, 2' calculated by the measurement unit 11, calculation unit 13, and information storage unit are calculated from the controller 15 to the motor drive (drive) 20 constituting the power unit. The signal is transmitted to the motor 21... to operate a drive mechanism (not shown) attached to the stage section 8 to adjust the position of the semiconductor wafer, and is also connected to the monitor television 22, 22 from the measurement section 11. and assist the worker.

By the way, the calculation section 13 calculates the relative position correction plate using the method described later, and in order to obtain the basic data, it sends the signals obtained from the ITV cameras 9 and 9' to the control sections 1o and 10' and converts them into video signals. Input to the measuring section 11. As mentioned above, this has a built-in image memory, and a calculation section 13.
Image input and image processing such as binarization, inversion binarization, image display, and character output to the screen are performed according to commands from .

The memo January 5 that constitutes the information storage section ■ is ROM and RAM.
The timer unit 16 stores the binary signals of the image memory, etc., and the timer unit 16 performs an internal interrupt to cause the calculation unit 13 to perform another process after a certain period of time in response to a command from the machine controller 19. Serial interface 1
7 has a function of converting parallel signals into time series signals, and also transmits the calculation results of the calculation section 13 to the machine controller 1.
However, since the parallel interface 18 is composed of a programmable ROM, it is also possible to transfer the calculation results obtained in the calculation section 13 to the machine controller by changing the software.

Next, to explain the semiconductor wafer position recognition means, the calculation unit 13 causes the measurement unit 11 to select the ITV camera 9 corresponding to the semiconductor wafer 2 for bonding, and after photographing a,
The image is input to the control unit 1o, converted into a video signal, inputted to the measurement unit 7, and after inversion and binarization is taken into the image memory and also stored in the memory 15. This binarized image is shown in FIG. 4, and the image after inversion and binarization is shown in FIG. Next, the arithmetic unit 13 sets areas 23 to 27 as shown in FIG. 6 in the inverted binarized image 2 obtained in the image memory in the measuring unit 11, and scans this area to obtain the image shown in FIG. 11. Detect P□ to P shown in FIG.

To show the method of detecting P□ to P, FIG. 7 shows an enlarged view of the region 23 in FIG. Count the number of bits from there.

In the diagram, the shaded area indicates the bit number 0'', and the white area indicates the bit number '''1''.The counted bit number is divided by 2 and added to the engineering coordinate value at the upper left corner of P□. The coordinate value is the y-coordinate, and the y-coordinate is obtained from the number of scanned lines.P2 is detected by scanning in the direction of the arrow from the upper left corner of FIG. '' part), memorize the coordinates of the maximum value of the white part, and count this maximum number of lines.

Divide the number of lines calculated by N by 2 and get the maximum value of y in the white part.
In addition to the coordinates, let it be the coordinate value of P2. Regarding P3, the 9th
As is clear from the enlarged view of the region 25 shown in the figure, the coordinate values are obtained by scanning from the upper left end in the direction of the arrow and in the same manner as in Pyu.2. As for P4 and P5, as shown in the enlarged view of Fig. 10, only one line in the vertical direction is scanned and the point where the bit becomes 1'0'' for the first time is memorized, and this position corresponds to the orientation flat part. The arithmetic unit 13 performs the operations P
Process ~P detects and determines the coordinates of the center position of the semiconductor wafer 2, and stores this in the memo January 5 of the information storage unit. Next, the inclination of this semiconductor wafer 2 is determined.As shown in FIG. 12, since it is equal to the angle formed by the orientation flat part 1 and the parallel line of the machine axis, jan"" of the distance of P4 and Ps in the machine direction y direction.
Since the slope θ can be calculated by determining θ, the result is also stored in the memory 15 as described above.

Next, regarding the semiconductor wafer 2' to be placed on the support section 3, the ITV camera 9' is selected according to a command from the calculation section 13, and the image is converted into a video signal by the control section 6' and inputted to the measurement section 11, and then the above-mentioned The binarized and inverted binarized images are taken into the image memory as shown in FIG. It is stored in the memory 15.

Furthermore, the means for calculating the relative position correction amount regarding these two semiconductor wafers 2.2' will be described. Regarding the equipment for bonding semiconductor wafers, as shown schematically in FIG. 14, the arm 28 is rotated to perform the bonding process while bringing the semiconductor wafer 2, that is, the wafer to be bonded, into close contact with the semiconductor wafer 2'. The coordinate values of the semiconductor wafer 2 to be bonded are converted into the coordinate values of the semiconductor wafer 2' to be bonded as a reference.

In this case, y/In is left unchanged as N, and only the construction coordinate is reversed around the construction axis, and a θ correction value is calculated in order to relatively match the primary orientation flat. The θ correction amount can be calculated from the inclination of the semiconductor wafer 2 to be bonded and the value of the semiconductor wafer 2' to be bonded, but as shown in FIG. It is assumed that the center of the stage 29 and the center of the ITV camera 9' coincide with each other), the center of the semiconductor woofer 2' becomes eccentric. The center coordinates of the semiconductor wafer 2' after this eccentricity are determined by the following formula.

(Village, t > = (C?・0-5ina) OC winter)
3'l sxnθ cosθ yl Here, (Step 1yyx) is the center position coordinate of the semiconductor wafer to be bonded, and CxLyi) is the center coordinate of the semiconductor wafer to be bonded after θ rotation. By finding the difference between the center position coordinates of the semiconductor wafers to be bonded after this rotation and the center position coordinates of the semiconductor wafers to be bonded converted into the coordinate system of the semiconductor wafers to be bonded, the relative position correction amounts of machining and y can be calculated. It can be calculated.

Such a procedure is executed by the calculation unit 13 and sent to the machine controller 19 via the serial interface 17 and the parallel interface 18 as described above.
Further, the motor driver 16..., motor 17... is operated to control the Δχ, ΔyΔθ stage 29.3 of the stage section 8.
After the position of the semiconductor wafer 2' to be bonded is corrected by moving the semiconductor wafer 2' by 0.31 mm, the arm 32 is operated to complete the bonding process.

〔Effect of the invention〕

In this way, the present invention visually recognizes the amount of positional deviation of each semiconductor wafer, consisting of the y-direction movement component and the θ movement component, and determines whether the semiconductor wafers are relative to each other based on one of the wafers. Since the position is corrected to match the above, workers can be freed from long hours of simple labor.

For this reason, it is possible to significantly improve productivity and quality deterioration due to eye strain of workers, as well as variations in quality caused by differences in skill level of workers, and this has an extremely large effect on mass production.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing a semiconductor wafer position recognition device according to the present invention. FIG. 2 is a sectional view showing the main parts of an illumination device used during imaging. FIG. 4
The figure shows the captured binarized image. Figure 5 is the inverted and binarized image of this image. Figures 6 to 10 are diagrams explaining the detection of the semiconductor wafer and the orientation flat part. FIG. 14 is a cross-sectional view showing the main parts of the equipment for the joining process.

Claims (1)

[Claims] A support part with a flat surface that fixes a semiconductor wafer for bonding, a stage part that makes this support part movable, a scattering plate arranged close to the flat surface of this support part, and a scattering plate that irradiates this scattering plate. a photoconductive conversion mechanism capable of capturing an image of the light source to input a silhouette of the semiconductor wafer; a control mechanism connected to the photoconductive conversion mechanism; and a measurement unit incorporating an image memory for inputting the output of the control mechanism; A bus connected to this, an information storage section and a calculation section that receive and receive signals from the measurement section via this bus, a power section that is connected to the stage section, and a power section that receives the output from the information storage section. A semiconductor wafer position recognition device comprising: a controller for transmitting information to a semiconductor wafer;