KR20040017484A - Exposing equipment and method for inspecting wafer alignment state - Google Patents

Abstract

PURPOSE: An exposure apparatus and a method for checking a wafer alignment state are provided to be capable of periodically and automatically checking the wafer alignment state for preventing wafer failure. CONSTITUTION: An exposure apparatus(100) is provided with a wafer storing stage(110) for storing exposure process object wafers and notch wafers, an alignment stage(120) for aligning the wafers, an exposure stage(130), and a plurality of transfer parts(150) for transferring the wafers to the wafer storing stage, the alignment stage, and the exposure stage. At this time, the exposure apparatus is connected to a server and host on line. The wafer storing stage includes a process progressing pot(112), a reproducibility measuring wafer pot(114), a notch wafer port(116) for loading a cassette inserted with notch wafers in order to correct misalignment, and a transfer pot(118).

Description

Exposing equipment and method for inspecting wafer alignment state

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus and a method for checking a wafer alignment state. In particular, a reproducibility measurement wafer for checking the reproducibility of alignment and a flat zone of the wafer are sensed to measure the degree of distortion of the optical sensor for aligning the wafer with respect to the reticle. The present invention relates to an exposure apparatus and a wafer alignment state checking method in which an alignment state can be automatically checked at a cycle set by a user while a notch wafer is always provided in a port of an exposure apparatus.

A semiconductor device or a semiconductor chip is generally laminated with a plurality of circuit pattern layers by performing lithography, exposure, ion implantation, chemical and mechanical polishing (CMP), chemical or physical vapor deposition, and plasma etching on a wafer formed of silicon. To form. These circuit patterns are formed by an exposure process in which a wafer on which photoresist is stacked is exposed to ultraviolet rays to transfer an image of a mask to a wafer, and an etching process of selectively etching a photoresist film according to the exposure.

In order to improve the reliability of the product, the circuit patterns already formed on the wafer and the circuit patterns to be newly formed through the exposure process must be exactly aligned. This means that the wafer to be exposed before the exposure process is performed with respect to the mask. This is done through Align to align.

In order to align the wafer, the optical system recognizes the alignment mark formed on the scribe line of the wafer cell area and performs the alignment, and an optical sensor that detects the flat zone portion of the wafer. To perform the alignment.

The exposure equipment for aligning wafers using an optical sensor includes a wafer storage stage in which a port into which a cassette loaded with predetermined wafers is placed, and an optical sensor for detecting a flat zone of a wafer on a predetermined portion of an upper surface thereof. Alignment stage for aligning the wafer before proceeding, exposure stage in which the exposure process for transferring the image of the mask to the wafer by exposing the wafer on which the photoresist film is formed to the wafer and the wafer storage stage, alignment stage and exposure stage It includes a conveying device for transferring to.

The operation of the exposure apparatus having the above-described configuration is briefly described as follows.

The transfer apparatus removes one wafer to be subjected to the exposure process from the cassette placed in the port of the wafer storage stage and transfers it to the alignment stage.

The wafer transferred to the alignment stage is rotated at a predetermined speed by a rotating device installed in the alignment stage, and the rotation of the wafer is continued until the optical sensor detects the flat zone of the wafer. When the flat zone of the wafer is detected by the optical sensor in this manner, the wafer is in alignment with the mask provided on the exposure stage.

The aligned wafer is then placed on the exposure stage by the transfer device. Then, an exposure process is performed in which ultraviolet rays are irradiated onto the wafer through a mask provided at an upper portion of the exposure stage at a predetermined interval from the exposure stage.

If the optical sensor is misaligned due to mechanical defects in the equipment or vibration of the align stage during the exposure process through the above-described process, and the optical sensor incorrectly sets the alignment position of the wafer, As the periodic inspection of the exposure equipment proceeds, the process of inspecting the alignment condition is performed.

The alignment condition inspection finds a cassette on which a predetermined number of reproducibility measurement wafers on which a flat zone is formed is placed, and the reproducibility measurement wafers are sequentially introduced into an exposure facility while the operator puts them in a port to measure the reproducibility of the wafer alignment.

When the reproducibility measurement wafers are inferior in reproducibility or out of alignment error tolerance, the operator again finds a nazi wafer having a sawtooth shaped nazi on the outer circumferential surface of the wafer and places a cassette on which the nazi wafer is loaded. Then, the transfer device places the Nazi wafer on the alignment stage, and the Nazi wafer measures the degree of distortion of the optical sensor through rotation, and then corrects the wafer to be within the tolerance range.

The alignment state inspection of the above-described method should be satisfied with post-processing when a large wafer quality accident occurs, and there is a problem in that the reliability of the product is lowered since the wafer quality accident has already occurred.

In addition, the reproducibility measuring wafer and the Nazi wafer must be found every time the alignment state inspection is performed, and the worker's labor force is increased because the operator must transfer the cassette loaded with the reproducibility measuring wafer and the bare wafer to the port.

In addition, there is a problem that the administrator can not monitor the reproducibility value of the reproducibility measurement wafer and how much the optical sensor is distorted.

Accordingly, the present invention has been made in view of such a conventional problem, and an object of the present invention is to prevent wafer quality accidents by allowing the inspection of alignment status to be automatically performed at every cycle set by an administrator.

In addition, another object of the present invention is to provide the convenience of the operator to monitor the data selected by the administrator in real time on the administrator computer.

It is still another object of the present invention to reduce the labor of an operator by adding a port to a wafer storage stage and always storing a cassette loaded with reproducibility measurement wafers and a cassette loaded with a Nazi wafer on the wafer storage stage.

1 is a conceptual diagram schematically showing the structure of an exposure apparatus according to the present invention.

FIG. 2 is a plan view illustrating a Nazi wafer measuring misalignment of an optical sensor when an alignment miss occurs in a process of checking an alignment state.

3A and 3B are flowcharts illustrating a method of checking a wafer alignment state.

4 is a block diagram illustrating a state in which an exposure apparatus, a host, and a facility server are connected online according to the present invention.

In order to achieve the object of the present invention, the present invention comprises the steps of exposing the photoresist film-coated wafer to an on-line exposure facility by the installation server and the host. If it is time to check the alignment state of the wafer, and if it is time to check the alignment state of the wafer, a predetermined number of reproducibility measuring wafers are put into the exposure equipment, and the reproducibility measuring wafers are aligned and reproducible within the alignment error tolerance. In the step of determining whether or not to have alignment reproducibility, the Nazi wafer is put into the exposure apparatus to measure the degree of distortion of the optical sensor that aligns the wafer, and the exposure stage is subjected to the exposure process to prevent alignment misalignment. Wafer alignment status check method comprising the step of correcting the position to provide.

Preferably, the data generated in each step is transmitted to the facility server through the host, and the facility server displays the authorized data in real time on the monitor of the facility server.

In order to achieve another object of the present invention, the present invention provides a wafer storage stage, a process port for placing a cassette on which wafers to be subjected to an exposure process, and a cassette on which reproducibility measurement wafers are loaded for measuring the degree of reproducibility of alignment. Reproducibility measurement wafer port on which the wafer is placed, Nazi wafer port on which a Nazi wafer is inserted to correct an alignment miss, and wafers taken out through the exposure stage are inserted into each cassette by type. Separated by ports.

Hereinafter, an exposure apparatus and an alignment state checking method according to the present invention will be described with reference to the accompanying drawings.

1 is a conceptual diagram illustrating an exposure apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the exposure apparatus 100 includes a wafer storage stage 110, an alignment stage 120, an exposure stage 130, an unloading stage 140, a transfer device 150, 152, and an exposure apparatus 100. A control unit (not shown) for controlling overall.

The wafer storage stage 110 includes a process port 112 in which a cassette on which wafers to be exposed are to be loaded is placed, and a cassette on which reproducibility measurement wafers 10 are measured to measure the degree of reproducibility of alignment. Reproducibility measurement wafer port 114, placed on the nazi wafer port 116 and the unloading stage 140 on which a cassette into which a nazi wafer 20 (see FIG. 2) is inserted to correct an alignment miss occurs. An export port 118 is provided in which wafers are taken out and loaded into empty carriers.

Here, as shown in FIG. 1, the reproducibility measurement wafer 10 is a wafer having a flat zone 12 in which a predetermined portion is cut flat on the edge surface, and the Nazi wafer 20 is a Nazi wafer (as shown in FIG. 2). A predetermined portion of the edge surface of 20 is a wafer having a sawtooth shaped Nazi groove 22, and the reproducibility measuring wafer 10 and the Nazi wafer 11 are always stored in the wafer storage stage 110.

The alignment stage 120 detects the flat zone of the wafer and aligns the wafer with respect to the mask in advance before transferring the wafer to be processed to the exposure stage 130. An optical sensor 122 is installed for detecting the flat zone of the wafer. Although not shown, the optical sensor 122 includes a light emitting device for irradiating a laser light and a light receiving device for detecting a flat zone by receiving light emitted from the light emitting device.

The exposure stage 130 is a portion where a wafer to be subjected to an exposure process is placed. Although not shown, a mask for forming a pattern on the wafer is formed on the exposure stage 130 spaced apart from the exposure stage 130 by a predetermined distance, and an ultraviolet irradiation device is provided on the mask.

On the other hand, the unloading stage 140 is a portion which waits for a while before the wafer, after the exposure process is completed, is transferred to the export port 118, and is installed to be aligned with the alignment stage 120.

Here, the alignment stage 120 and the unloading stage 140 are installed between the wafer storage stage 110 and the exposure stage 130.

On the other hand, the transfer device (150,152) is composed of a first transfer robot 150 and a second transfer robot (152). The first transfer robot 150 removes a predetermined wafer from a cassette located at each of the ports 112 to 116 and loads a wafer on which a process is completed into a cassette placed at a transfer port 118. The first transfer robot 150 Is installed between the wafer storage stage 110 and the unloading stage 140.

The second transfer robot 152 receives a predetermined wafer to be processed from the first transfer robot 150 and transfers the wafer to the alignment, exposure, and unloading stages 120, 130, and 140. It is installed between the unloading stage 140.

A method of checking an alignment state of a wafer at a set period by a user in the exposure apparatus configured as described above will be described with reference to FIGS. 3A and 3B.

In order to check the alignment state of the wafer, the user sets the alignment state checking cycle in units of one day, a main unit, and a number of wafers, and transmits them to the exposure facility 100.

Then, a cassette in which these wafers 10 and 20 are loaded is placed in the reproducibility measurement wafer port 114 and the nazi wafer port 116 of the wafer storage stage 110, and the process port 112 is a port in the preceding process. The cassette in which the wafers on which the race film was formed were loaded is placed.

When the carriers are placed on the wafer storage stage 110 as described above, the process is performed in the order shown in FIG. 3A.

That is, an exposure process of removing the wafer to be processed from the process port 112 and transferring the mask pattern to the photoresist film is performed (step 200).

During the exposure process, the controller continuously determines whether to perform the alignment state check based on the alignment state check period preset by the manager (step 210).

If it is determined that the alignment state is not to be checked, the flow returns to step 200 to continue the exposure process.

However, if it is time to check the alignment state, the control unit transmits an electrical signal to the transfer apparatus (150,152). Then, the first transfer robot 150 takes out the reproducibility measurement wafer 10 one by one from the cassette of the reproducibility measurement wafer port 114 and transfers it to the second transfer robot 152, and the second transfer robot 152 transfers the transfer. The received reproducibility measurement wafer 10 is placed on the alignment stage 120 (step 220).

Here, the first transfer robot 150 takes out 5 reproducibility measurement wafers 10 for a predetermined number and transfers them to the second transfer robot 152 in turn.

When the reproducibility measurement wafer 10 is placed on the alignment stage 120, the reproducibility measurement wafer 10 is rotated at a predetermined speed by a rotation apparatus installed on the alignment stage 120, and the rotation of the reproducibility measurement wafer 10 is rotated. The process continues until the light sensor 122 detects the flat zone 12.

When the reproducibility measurement wafer 10 whose alignment has been completed by the flat zone detection of the optical sensor 122 is placed on the exposure stage 130 by the second transfer robot 152, the control unit controls the reproducibility measurement wafer 10 whose alignment has been completed. ) Is measured how much reproducibility is within the alignment error tolerance.

When all five preset reproducibility measuring wafers 10 are input to the exposure apparatus 130 and the measurement of reproducibility is completed in the alignment, the controller determines that the five reproducibility measuring wafers 10 are based on the reproducibility measurement result values. It is determined whether all of them are within the allowable tolerance range (step 230).

If the reproducibility measurement wafers 10 existed within the alignment tolerance range, the photoresist-coated wafer is introduced into the exposure facility 100 to resume the exposure process (step 240).

On the other hand, if any one of the reproducibility measuring wafers 10 is beyond the tolerance tolerance range, a predetermined process is performed by the flowchart shown in FIG. 3B.

That is, the control unit transmits an electrical signal to the first transfer robot 150, and the first transfer robot 150 draws a piece of Nazi wafer 20 placed on the Nazi wafer port 116 from the cassette according to the electrical signal of the control unit. To the second transfer robot 152. Then, the second transfer robot 152 places the Nazi wafer 20 on the upper surface of the alignment stage 120 (step 300).

When the Nazi wafer 20 is placed on the alignment stage 120 as described above, the rotating device installed on the alignment stage 120 rotates the Nazi wafer 20 to position the nazi groove 22 on the optical sensor 122. . Then, the controller measures how much the optical sensor 122 is displaced from the preset value by using information such as the area of the nazi groove 22 and the amount of light incident on the light receiving unit through the nazi groove 122 ( Step 310).

Then, the electrical signal is transmitted to the exposure stage 130 so that the optical sensor 122 finely moves the exposure stage 130 in the X and Y directions by a distorted value so that the wafer is aligned within the error tolerance with respect to the mask. The miss is corrected (step 320).

Thereafter, in step 320, the controller transmits an electrical signal to the transfer apparatus to check whether the correction is made correctly. Then, the first transfer robot 150 takes out the reproducibility measurement wafers 10 one by one from the cassette of the reproducibility measurement wafer port 114 and transfers them to the second transfer robot 152, and the second transfer robot 152 transfers them. The received reproducibility measurement wafer 10 is placed on the alignment stage 120 (step 330).

Subsequently, when the reproducibility measurement wafer 10 is placed on the alignment stage 120, the reproducibility measurement wafer 10 is rotated at a predetermined speed by a rotation apparatus installed in the alignment stage 120, and the reproducibility measurement wafer 10 is disposed on the alignment stage 120. Rotation continues until the optical sensor 122 detects the flat zone 12.

When the reproducibility measurement wafer 10 whose alignment has been completed by the flat zone detection of the optical sensor 122 is placed on the exposure stage 130 by the second transfer robot 152, the control unit controls the reproducibility measurement wafer 10 whose alignment has been completed. ) Is measured how much reproducibility is within the alignment error tolerance.

When all of the five reproducibility measuring wafers 10 set in advance are input to the exposure apparatus 130 and the measurement of reproducibility is completed in the alignment, the controller determines five reproducibility measuring wafers 10 based on the reproducibility measurement result values. In step 340, it is determined whether all of?) Are within the tolerance tolerance range.

If all of the reproducibility measurement wafers 10 are within the allowable tolerance range, the wafer coated with the photoresist film is introduced into an exposure facility and the exposure process is performed (step 350).

If any of the reproducibility measuring wafers 10 is out of the alignment error tolerance range, the feedback is fed back to step 300 to re-correct the alignment miss.

Meanwhile, as illustrated in FIG. 4, the exposure facility 100 is online with the facility server 400 and the host 500 so that an administrator can monitor all data generated in the process of checking the alignment state.

That is, the host 500 provides various data necessary for exposure to the exposure facility 100, inputs all data transmitted from the exposure facility 100, that is, data generated in the process of checking the exposure process and the alignment state. Save it.

In addition, the host 500 uses a predetermined protocol, for example, the SECS protocol, which is a protocol used between semiconductor devices, and the like, the data requested by the administrator through the facility server 400, that is, data generated by checking the alignment state. Send to the facility server 400 in real time.

Then, the facility server 400 receives and stores the alignment status check data requested by the manager from the host 500, and stores the alignment status check data on the monitor (not shown) of the facility server 400 so that the manager can recognize the alignment status check data. Display in real time.

As described in detail above, by installing ports for storing Nazi wafers and reproducible measurement wafers in the wafer storage stage, and allowing the alignment status to be automatically checked at intervals set by the administrator, the labor of the worker is reduced, There is an effect that can improve the yield of the product by preventing the quality of the wafer in advance.

In addition, there is an effect of providing convenience for the administrator to monitor all data generated in the process of checking the alignment status by the exposure equipment, the facility server and the host online.

In the detailed description of the present invention described above with reference to a preferred embodiment of the present invention, those skilled in the art or those skilled in the art having ordinary knowledge in the scope of the invention described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

Claims (5)

In the facility server, the host checks the state that the wafer is aligned to the online exposure equipment, Injecting a wafer coated with a photoresist film into the exposure apparatus to perform an exposure process; Determining whether it is time to check the state of whether the wafer placed in the exposure apparatus is correctly aligned; When the alignment state of the wafer is to be checked, determining whether the reproducibility measurement wafers have an alignment reproducibility within an alignment error tolerance range by inserting a predetermined number of reproducibility measurement wafers into the exposure apparatus; If the alignment is not reproducible, a Nazi wafer having a Nazi groove formed on a predetermined portion of the outer circumferential surface thereof is introduced into the exposure apparatus to measure the degree of distortion of the optical sensor for aligning the wafer, and the exposure process is performed so that an alignment miss does not occur. And correcting the position of the exposure stage in progress. The wafer alignment as claimed in claim 1, wherein the data generated in each step is transmitted to the facility server through the host, and the facility server displays the authorized data on a monitor of the facility server in real time. How to check the status. The method of claim 1, wherein the checking of the alignment state in the determining of whether the alignment state of the wafer is to be checked is one unit previously set by a manager among a daily unit, a main unit, and a wafer number unit. Wafer alignment status check method, characterized in that determined based on. A wafer storage stage in which a cassette on which a wafer to be subjected to the exposure process is to be stored is stored, and each cassette into which a wafer for measuring alignment reproducibility and Nazi wafers for inserting an alignment miss is inserted is always stored; An alignment stage on which an optical sensor is installed on a predetermined portion of the upper surface to align the wafer before the exposure process; An exposure stage on which the wafer aligned in the alignment stage is placed and exposing the wafer according to a mask pattern; And A transfer device for transferring the wafer to the wafer storage stage, the alignment stage, and the exposure stage, Exposure equipment, characterized in that connected to the server and the host online. 5. The wafer storage stage of claim 4 wherein the wafer storage stage is A process progress port on which a cassette on which wafers to be subjected to the exposure process will be placed is placed; A reproducibility measurement wafer port on which a cassette loaded with the reproducibility measurement wafers for measuring the reproducibility degree of the alignment is placed; A Nazi wafer port on which a cassette into which a Nazi wafer is inserted to correct the misalignment occurs; And And an export port into which the wafers carried out through the exposure stage are inserted into the respective cassettes for each type.