JPH0982784A - Substrate processing method - Google Patents

Abstract

(57) Abstract: A substrate processing method capable of achieving high throughput while performing relatively accurate positioning. When processing a first substrate in a lot, a positional displacement amount (offset, rotation) in a two-dimensional plane and a substrate strain amount (scaling, orthogonality, etc.) are measured, and these measurements are performed. Predetermined processing is performed using the result (steps 104 → 106 → 108 → 110), 2
For the first and subsequent substrates, only the positional deviation amount of the substrate in the two-dimensional plane is measured, and the strain amount obtained for the first substrate is used as it is to perform a predetermined process (step 104 → 106 →
110). For this reason, the time required for processing can be realized by adding a little time to the method of measuring only the positional deviation amount in the two-dimensional plane while maintaining the same accuracy as the method of measuring the distortion amount for each substrate. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate processing method, and more particularly, to an apparatus for continuously performing alignment and processing on a substrate, for example, a semiconductor manufacturing apparatus such as an exposure apparatus or a laser repair apparatus. The present invention relates to a substrate processing method.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, in many apparatuses such as a reduction projection exposure apparatus, measurement for aligning a wafer (substrate) is performed, and the result is used to perform processing while positioning the wafer at a predetermined position. . As a first measuring method for aligning the wafer, a positional deviation amount (offset) in the XY two-dimensional direction and a positional deviation amount (rotation) in the rotation direction around the Z-axis (θ direction) within an XY two-dimensional plane are used. There is a method of measuring only the amount of positional deviation (hereinafter referred to as "first method").

However, since the wafer is subjected to various chemical treatments and heat treatments during the manufacturing process, it expands and contracts, and the first method has a problem in positioning accuracy.

As a second method for preventing such inconvenience, there is a method of measuring a positional deviation amount (alignment measurement) and alignment for each chip (each shot area), which is called a field-by-field. However, in this method, the ratio of the alignment processing to the whole becomes high, and the processing capacity (throughput) of the apparatus is lowered.

As a third method used to improve the inconvenience of the reduction of the processing capacity by the second method, in addition to the above-mentioned offset and rotation for each wafer, the distortion amount of the coordinate system, for example, the scaling (scaling). ), The orthogonality is obtained, and positioning is performed for all the chips (shot areas) of the wafer based on these four measured quantities (parameters). Various methods for measuring the above-mentioned four parameters (see JP-A-61-44429) have been devised.

Nowadays, the third method is predominant because both accuracy and processing capacity per unit time are required.

FIG. 3 shows an example of a control algorithm adopting the third conventional method.

[0008]

However, in the above-mentioned third method, as is clear from FIG. 3, the alignment of the wafer in the X / Y / θ direction is performed every time the wafer (substrate) is processed. In addition to the measurement of offset and rotation, the amount of distortion of coordinates (coordinate correction data) such as scaling and orthogonality is measured every time, which requires more time for alignment as compared with the first method described above. There was an inconvenience that the throughput decreased.

The present invention has been made in view of the above-mentioned disadvantages of the prior art, and an object thereof is to provide a substrate processing method capable of achieving high throughput while performing relatively accurate alignment. To do.

[0010]

Means for Solving the Problems Semiconductor integrated circuit (IC)
In the manufacturing process, 25 or 50 wafers as a substrate are usually treated as one lot in all lots, so that all wafers in a lot are almost affected by heat or the like. Is considered to be. Therefore, if the influence is the same, it is considered that the deformation (distortion) of the wafer caused by that is also occurring. In the present invention, focusing on this point, the following configuration is adopted.

That is, the present invention is a substrate processing method used in an apparatus for continuously aligning and processing a substrate and measuring the amount of positional deviation of a first substrate in a two-dimensional plane. A first step; a second step of measuring the amount of strain of the substrate; and a processing point or region based on the measurement results of the first step and the second step after the first step and the second step are performed in random order. A third step of performing a predetermined process on the substrate while positioning the substrate for each of them; and thereafter, measuring the positional deviation amount in the two-dimensional plane for each of the second and subsequent substrates, and the measurement result and the above. By performing the predetermined processing on each of the second and subsequent substrates while positioning each of the second and subsequent substrates for each processing point or region based on the strain amount measured in the second step, the second and subsequent substrates are processed. Repeat alignment and processing Return and a fourth step.

According to this, when the substrates are processed in lot units, when the first substrate is processed, the positional displacement amount (offset, rotation) within the two-dimensional plane and the substrate distortion amount (scaling, orthogonality). Etc.) is measured,
Predetermined processing is performed on the substrate while positioning the substrate for each processing point or region using these measurement results. However, for the second and subsequent substrates, the positional displacement amount of the substrate in the two-dimensional plane For the distortion amount, the distortion amount obtained for the first substrate is used as it is, and the predetermined processing is performed on each substrate while positioning the second and subsequent substrates for each processing point or region. To be done. Therefore, the time required for the processing is slightly different from that of the first method of measuring the offset and rotation while maintaining the same degree of accuracy as the third method of measuring the distortion amount (scaling, orthogonality) for each substrate. This can be achieved by just adding time, and the processing capacity can be improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a schematic configuration of a laser processing apparatus (laser repair apparatus) 10 according to an embodiment for carrying out the processing method according to the present invention. This laser processing apparatus 10 is a horizontal plane (reference plane) orthogonal to the plane of FIG.
The XY stage 12 that moves in the two-dimensional direction and the X
A Z stage 14 provided on the Y stage 12, an irradiation optical system (which will be described later) for irradiating a laser beam for processing on a wafer W as a substrate placed on the Z stage 14. An optical system for observing a processed part (which will be described later), a laser interferometer 16 for detecting the moving position of the XY stage 12, and a main control for controlling the moving position of the XY stage 12 and the emission timing of laser light. And a device 18.

The irradiation optical system is a light quantity adjusting unit 2 for adjusting the quantity of laser light L1 emitted from the laser light source 20.
2 and the laser light L1 that has passed through the light quantity adjusting unit 22
Beam splitter 24 that reflects toward the Y stage 12
And the laser light L reflected by the beam splitter 24
1. The objective lens 26, whose optical axis is arranged in a state of being orthogonal to the reference plane, is formed in the forward direction of 1.

The observation optical system includes a half mirror 30 for reflecting the observation illumination light L2 from the illumination light source 28 toward the objective lens 26, and the observation illumination light L2 having the same optical axis as the laser light L1. The objective lens 26 for irradiating the wafer W with the CCD camera 32 for receiving the reflected light from the wafer W through the objective lens 26, the beam splitter 24 and the half mirror 30 and the CCD camera 32 placed at a position conjugate with the surface of the wafer W. It is composed of. This CCD camera 32
A television monitor 34 is installed side by side.

According to this observation optical system, the illumination light L2
After being reflected by the half mirror 30, the objective lens 26
Thus, the wafer W is irradiated with the same optical axis as the laser light L1. The illumination light L2 applied to the wafer W is reflected by the wafer W, the reflected light is detected by the CCD camera 32, and the processing state can be observed by the television monitor 34.

The XY stage 12 is driven by a drive system 36 including a motor (not shown), and the drive system 36 is controlled by the main controller 18. The drive system 36 is
The drive system for the X drive of the XY stage, the drive system for the Y drive, and the drive system of the Z stage 14 are representatively shown.
Therefore, the Z stage 14 is also driven by the drive system 36 along the optical axis direction of the objective lens 26.

The main controller 18 is composed of a microcomputer or a minicomputer. The main controller 18 monitors the measurement value of the laser interferometer 16 and monitors the machining points stored in an internal memory (not shown). While positioning the XY stage 12 on the optical axis of the objective lens 26 via the drive system 36 according to the data and a predetermined procedure,
By controlling the emission timing of the laser light of the laser light source 20, the fuse group as a workpiece arranged on the wafer W in the XY two-dimensional directions is processed. Here, in practice, the X-axis laser interferometers 16X and Y
Although there is a laser interferometer 16Y for axes, these are typically shown as the laser interferometer 16 in FIG.

In the internal memory of the main controller 18, a control algorithm for processing the workpiece as described later,
Processing data such as the coordinate position of the work piece and other conditions for signal processing are registered in advance.

Further, in the present embodiment, a mark position detecting device (image processing device) 38 is provided at the output stage of the CCD camera 32, and this mark position detecting device 38 has a CCD.
Processing such as detecting the position of an alignment mark (not shown) on the wafer W is performed based on the image signal from the camera 32. The processing result of the mark position detecting device is transmitted to the main control device 18, and the main control device 18 drives the drive system 36 based on the information, the control algorithm, the processing data and the like.
The XY stage 12 is driven via the XY stage to perform positioning on the optical axis of the objective lens for each processing point, and the laser light L1 emitted from the laser light source 20 is controlled via the light quantity adjusting unit 22 to have an appropriate light quantity. Then, the fuse group (workpiece) is processed.

In FIG. 1, reference numeral 40 indicates an operation panel. This operation panel 40 is used when the television monitor 3 cannot perform an automatic alignment process.
It is used for an operator to manually perform an alignment operation while looking at 4.

Next, the operation of the laser processing apparatus 10 when processing the wafer W in lot units is performed by the C in the main controller 18.
The PU control algorithm will be described with reference to the flowchart of FIG. Here, at the stage when this control algorithm starts, a counter (to be described later) is reset (n
← 0).

At step 100, the wafer W of the wafer transfer system (not shown) is driven to perform rough alignment (pre-alignment) in the X / Y / θ directions on the pre-alignment device (not shown). Is loaded on the Z stage 14, and then the routine proceeds to step 102, where a counter (not shown) is incremented by 1 (count value n ← n + 1).

In the next step 104, X / Y / θ is detected based on the detection result of the alignment mark (not shown) for detecting the positional deviation in the X / Y / θ direction by the mark position detecting device 38.
After measuring the positional displacement amount in the direction, that is, the offset and rotation, the process proceeds to step 106, and it is determined whether or not the wafer W is the first wafer in the lot. This judgment is made by judging whether or not the count value n of the counter is "1". If it is the first wafer, since the count value n of the counter is "1" by being incremented in step 102, the determination in step 106 is affirmative, and the process proceeds to step 108 to mark. After measuring the coordinate correction data (distortion amount), that is, the scale and the orthogonality based on the detection result of the alignment mark (not shown) for detecting the distortion amount of the position detecting device 38, the process proceeds to step 110.
On the other hand, if the determination in step 106 is negative, the process jumps to step 110. The determination in step 106 is denied when the count value n of the counter is 2 or more, that is, in the case of the second and subsequent wafers in the lot.

In step 110, positioning is performed on the optical axis of the objective lens for each processing point of the workpiece on the wafer W based on the offset, rotation, scaling, and orthogonality data measured in steps 104 and 106. By controlling the emission timing of the laser light of the laser light source 20, the fuse group (workpiece) on the wafer W mounted on the Z stage 14 is processed. At the same time as the alignment of each processing point, the Z stage 14 is driven by the drive system 36 based on the output of the focus detection system (not shown), and so-called autofocusing is performed.

In the next step 112, it is judged whether or not the count value n of the counter reaches the total number of wafers n ₀ in the lot, thereby judging whether or not the wafer is the last wafer. If the determination is negative, the process proceeds to step 114, the wafer is exchanged using the wafer unloading arm and the loading arm of the wafer transfer system (not shown), the next wafer is loaded on the Z stage 14, and then step Returning to step 102, the processes and determinations of steps 102 to 114 are repeated thereafter. On the other hand, when the processing of all the wafers in the lot is completed and the determination in step 112 is affirmed, the series of processes of this routine is completed.

As described above, in the present embodiment, when the wafer (substrate) is processed in lot units, when the first wafer is processed, the offset and rotation are measured (step 104), and further scaling is performed. The orthogonality (coordinate distortion correction amount) is measured (step 106), and for the second and subsequent wafers, only the positional deviation amount of the substrate within the two-dimensional plane of offset and rotation is measured, and the distortion amount is measured. I decided to use the amount of distortion found on the first sheet as is. According to this, the distortion amount (coordinate correction data) of the second and subsequent substrates is not measured, and the coordinate correction data of the first substrate is applied as it is, (total number of wafers-1) x distortion amount. The processing time for the measurement time is saved, and the processing capacity per unit time of the device can be improved. In other words, according to the present embodiment, the time required for processing is offset while maintaining the same degree of accuracy as the above-mentioned third method of measuring the distortion amount (scaling, orthogonality) of the coordinate system for each wafer. It can be realized by adding a little time to the first method that measures only rotation,
It is possible to improve the processing capacity.

The processing method according to the present invention, in addition to the third method described above, that is, the offset and rotation for each wafer, calculates the distortion amount of the coordinate system, for example, the scale (scaling) and the orthogonality, The so-called enhanced global alignment (EG), which belongs to a method of performing positioning and processing for all chips (exposure shots) of the wafer based on four measured quantities (parameters)
The effect is particularly expected when A) is applied to wafers processed in lot units. That is, in EGA, an alignment detection system (for example, LSA (laser step alignment)) is used to detect mark positions of an arbitrary number of shots in a wafer, as described in, for example, Japanese Patent Laid-Open No. 61-44429. Detected, and statistically processing each measurement result, the offset of the wafer,
Parameters such as rotation, scaling, and orthogonality are calculated by calculation, and each shot is sequentially positioned based on the calculation result. In this case, only the first wafer in the lot is offset or rotated. , Scaling, orthogonality, etc.,
This is because, for the second and subsequent wafers, if only the offset and rotation are calculated, the calculation becomes very simple and the calculation time is significantly shortened.

Although the laser processing apparatus for carrying out the processing method according to the present invention has been described in the above embodiment, the scope of application of the present invention is not limited to this, and the present invention is continuously applied. Any apparatus such as an exposure apparatus can be applied as long as it is an apparatus that performs alignment and processing on a substrate.

[0031]

As described above, according to the present invention,
There is an unprecedented excellent effect that high throughput can be realized while relatively relatively accurately aligning substrates.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of a laser processing apparatus according to an embodiment.

FIG. 2 is a flowchart showing a main control algorithm of a CPU in the main control device of FIG.

FIG. 3 is a flowchart showing an example of a control algorithm that employs a third conventional method.

[Explanation of symbols]

 10 Laser Processing Device 20 Laser Light Source 26 Objective Lens 38 Mark Position Detection Device W Wafer (Substrate)

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location H01L 21/027 H01L 21/30 520A

Claims (1)

[Claims] 1. A method of processing a substrate used in an apparatus for continuously aligning and processing a substrate, comprising: a first step of measuring a displacement amount of a first substrate in a two-dimensional plane. A second step of measuring the strain amount of the substrate; and the substrate for each processing point or region based on the measurement results of the first step and the second step after the first step and the second step are performed in random order. And a third step of subjecting the substrate to a predetermined treatment while positioning the substrate; and thereafter measuring the amount of positional deviation in the two-dimensional plane for each of the second and subsequent substrates,
Based on this measurement result and the amount of strain measured in the second step, each substrate after the second substrate is positioned for each processing point or region, and each substrate is subjected to a predetermined process to obtain two substrates. A substrate processing method, including the fourth step of repeating the alignment of the substrate after the eyes and the treatment.