TWI752617B - Wafer offset correction method for maskless exposure machine - Google Patents

Abstract

A method for correcting wafer offset of a maskless exposure machine, wherein the wafer is bonded to a substrate, the substrate has a plurality of contact holes, the wafer has a plurality of contacts, and each contact is pre-exposed to form a connection to the The guiding part of each contact hole; the calibration method includes: obtaining state information of the chip by a first pre-scanning method, including shape and position information; comparing the state information of the chip with a reference state, and calculating the The reference state is corrected to a compensation value consistent with the state information of the wafer; a compensation segment of an exposure area is calculated according to the compensation value, so that each lead part can form an exposure pattern at the corresponding contact hole position.

Description

Wafer offset correction method for maskless exposure machine

The present invention relates to a yellow light lithography process, in particular to a wafer offset correction method for a maskless exposure machine.

In the manufacturing process of integrated circuits, the chip has a plurality of contacts, and the substrate of the wafer is provided with contact holes corresponding to the number of contacts. Each contact is formed with a conductive portion forming a circuit, wherein the other end of each conductive portion should be formed at a position corresponding to each contact hole, so that the external circuit can be correctly connected to the conductive portion in the subsequent manufacturing process. However, as shown in FIG. 7A , after the wafer 6 is bonded to the substrate 7 , the position may deviate from the standard position due to an operation error, so as shown in FIG. It also deviates from the correct position, so that it cannot correspond to the contact hole 71 of the substrate 7 accurately, and it is difficult to ensure the correctness of the connection with the external circuit in the subsequent process.

A conventional method to solve the above problem is to enlarge the area of the substrate contact hole 71 , so that the offset guide portion 81 can still fall within the range of the contact hole 71 when an error occurs in the die bonding of the wafer 6 . However, with the advancement of materials and technology, the volume of the wafer 6 and the substrate 7 is getting smaller and smaller, and the structure is getting more and more refined, so the area of the contact hole 71 cannot be improved enough; on the other hand, enlarging the area of the contact hole 71 will lead to The structural strength of the substrate 7 is reduced, which makes the substrate 7 more likely to collapse, so it is not a good solution.

On the other hand, the situation that the wafer 6 is poorly bonded to the substrate 7 includes high and low inclination or warping as shown in FIG. 7B, so that when the formed lead portion is exposed, the focal point of the light 9 will be as shown in Fig. 7B. As shown in Fig. 9, the wafer 6 cannot be accurately hit, and the line width of the formed guide portion 82 is enlarged (see Fig. 8), and the smaller the wafer, the more serious it affects the product quality. .

In order to solve the above problems in the prior art, a distance measuring device is installed on the exposure machine to measure the distance between the light source and the wafer. When the exposure machine is used for exposure, the distance measurement is performed at the same time, and the distance information is sent back immediately. The exposure focus is adjusted to keep the exposure focus on the wafer. However, as shown in Figure 9, the light source 9 moves very fast for exposure. In contrast, it takes too long for the distance measuring device to measure the distance and then control the exposure machine to change the focal length, so that it cannot keep up with the movement of the light source 9. speed, it still cannot solve the problem of excessive exposure line width.

In view of this, how to improve the above problem is the primary problem to be solved by the present invention.

The main purpose of the present invention is to provide a wafer offset correction method for a maskless exposure machine, which calculates a compensation section according to the shape and position of the wafer bonding on the substrate, so as to change the position of the exposure pattern, so as to make The exposure pattern can be formed on the corresponding contact hole position to achieve the effect of correcting the error caused by the offset of the sticky die.

In order to achieve the aforementioned purpose, the present invention provides a wafer offset correction method for a maskless exposure machine, wherein a wafer is bonded to a substrate, the substrate has a plurality of contact holes, and the wafer has a plurality of contacts, which are respectively connected to each other. Predetermined exposure on the contacts forms a guide portion connected to each contact hole; the calibration method includes: Obtain the state information of the wafer by a first pre-scanning method, including shape and position information; compare the state information of the wafer with a reference state, and calculate and correct the reference state to be consistent with the state information of the wafer Compensation value; according to the compensation value, a compensation segment of the exposure area is calculated, so that each lead part can form an exposure pattern at the corresponding contact hole position.

Preferably, the first pre-scanning means is to capture the image of the wafer on the substrate.

In one embodiment, the calibration method further includes: obtaining the elevation information of the wafer by a second pre-scanning method; inputting the elevation information of the wafer into the maskless exposure machine, so that the maskless exposure machine performs exposure during exposure. The focus is adjusted according to the elevation information of the wafer, so that the focus of exposure is always on the wafer.

Preferably, the second pre-scanning means is to measure the distance between it and the wafer with a laser range finder.

The above-mentioned objects and advantages of the present invention can be easily understood from the detailed description and accompanying drawings of the following selected embodiments.

1: Wafer

10: Contact

2: Substrate

21: Access hole

3: Guide part

4: Compensation section

5: Light

6: Wafer

7: Substrate

71: Access hole

81, 82: guide part

9: Light

Fig. 1 is a flow chart of the wafer offset correction method of the present invention, which is used to correct the position of the exposure pattern; Fig. 2 is a schematic diagram of an image showing the wafer status information of the present invention; Fig. 3 is a schematic diagram of a reference file of the present invention; Figure 5 is a schematic diagram of the result after calibration using the method of the present invention; Figure 5 is a flow chart of the wafer offset correction method of the present invention for correcting the line width of the exposure pattern; Figure 6 is the operation of the exposure machine after calibration using the method of the present invention Process diagram; Figures 7A and 7B are schematic diagrams of conventional wafer bonding on the wafer; Figure 8 is a schematic diagram of exposure patterns after exposure of conventional defective chips; Figure 9 is the operation process of the exposure machine when conventional defective chips are exposed Schematic.

The present invention provides a chip offset correction method for a maskless exposure machine, which is applied to a chip structure bonded to a wafer substrate, wherein the substrate 2 has a plurality of contact holes 21, and the chip 1 has a plurality of contacts 10. Each contact 10 can be exposed by a maskless exposure machine to form a lead portion 3 serving as a circuit. The lead portion 3 is intended to extend to the corresponding contact hole 21 on the substrate 2 .

The calibration method of the present invention, as shown in FIG. 1, includes: obtaining state information of the wafer, including shape and position information, by a first pre-scanning means; comparing the state information of the wafer with a reference state, And calculate the compensation value that corrects the reference state to be consistent with the state information of the chip; calculates a compensation segment of an exposure area according to the compensation value, so that each lead part can form an exposure pattern at the corresponding contact hole position.

In the process of bonding the wafer 1 to the wafer substrate 2 (also known as die bonding), as shown in Fig. 2, the situation may sometimes deviate from the predetermined position, so that the conductive portion 3 formed by the predetermined exposure is also As a result, it deviates from the correct position, so that it cannot correspond to the contact hole 21 of the substrate 2 accurately, and it is difficult to ensure the correctness of the connection with the external circuit in the subsequent process. Therefore, the calibration method of the present invention first obtains the state information of the wafer 1 by a first pre-scanning means, including shape and position information; in this embodiment, the first pre-scanning means captures the wafer by an image capture device 1. The image on the substrate 2. The captured image is as shown in FIG. 2, in which information such as the shape and position of the wafer 1 on the substrate 2 can be analyzed. catch Then, the state information of the wafer 1 is compared with a reference file as shown in FIG. 3, wherein the reference file has reference state information such as the correct shape and position of the wafer 1 on the substrate 2, and is aligned with the wafer reference The position of the outer ring of the gear (UBM) and the alignment of the actual chip internal pins (DIE PAD) are used as benchmarks. After comparison, the difference between the two can be obtained, and then the drawing file of the lead part can be adjusted by linear or nonlinear numerical calculation. , and then calculate the compensation value for correcting the reference state to be consistent with the actual shape and position of the wafer 1 . Accordingly, a compensation section 4 of the exposure area is calculated according to the compensation value, so that the exposure pattern of each lead portion 3 can be connected to the corresponding contact hole 21 through the compensation section 4 as shown in FIG. 4 . A continuous and unbroken wiring is formed between each contact point 10 of the wafer 1 and the corresponding contact hole 21, so as to correct the error caused by the offset of the die bonding.

Furthermore, as shown in FIG. 5, the present invention further provides a method for calibrating the exposure line width, which includes: obtaining the elevation information of the wafer by a second pre-scanning method; inputting the elevation information of the wafer into a matte The mask exposure machine enables the maskless exposure machine to adjust the focal length according to the elevation information of the wafer during exposure, so that the exposure focus is always located on the wafer.

The above-mentioned second pre-scanning means may be a laser range finder, which depicts the elevation information of the wafer by measuring the distance between it and the wafer. The above-mentioned second pre-scanning means is implemented before the exposure operation is started, so as to obtain the elevation information of the wafer in advance; preferably, the second pre-scanning means can be performed together with the aforementioned first pre-scanning means. Then, the obtained wafer elevation information is input into the maskless exposure machine, so that it can change the exposure focal length in real time according to the pre-acquired elevation information of the wafer 1 during the exposure process, as shown in Fig. 6, so that the light 5 The focal point is always kept on the wafer 1, thereby maintaining the exposed line width without being enlarged, so as to improve the yield of the product.

However, the disclosure of the above embodiments is only used to illustrate the present invention, not to limit the present invention, and the replacement of equivalent elements should still belong to the scope of the present invention.

To sum up, those skilled in the art can understand that the present invention can achieve the above-mentioned purpose, and it complies with the provisions of the Patent Law.

Claims (4)

A method for correcting wafer offset of a maskless exposure machine, wherein the wafer is bonded to a substrate, the substrate has a plurality of contact holes, the wafer has a plurality of contacts, and each contact is pre-exposed to form a connection to the The guide portion of each contact hole; the calibration method includes: obtaining state information of the chip, including shape and position information, by a first pre-scanning means; comparing the state information of the chip with a reference state, and calculating Correcting the reference state to a compensation value consistent with the state information of the chip; calculating a compensation segment of the exposure area according to the compensation value, wherein the compensation segment is connected from each lead portion to the corresponding contact hole, so that the chip is A continuous and uninterrupted wiring is formed between each contact and the corresponding contact hole. The wafer offset correction method for a maskless exposure machine according to claim 1, wherein the first pre-scanning means is to capture an image of the wafer on the substrate. The wafer offset correction method for a maskless exposure machine as claimed in claim 1, further comprising: obtaining the elevation information of the wafer by a second pre-scanning means; inputting the elevation information of the wafer into the maskless exposure machine , so that the maskless exposure machine adjusts the focal length according to the elevation information of the wafer during exposure, so that the exposure focus is always located on the wafer. The wafer offset correction method for a maskless exposure machine according to claim 3, wherein the second pre-scanning means is to measure the distance between the wafer and the wafer with a laser range finder.

Images