WO2006098266A1

WO2006098266A1 - Mask cleaning method

Info

Publication number: WO2006098266A1
Application number: PCT/JP2006/304885
Authority: WO
Inventors: Jun Nitta; Masashi Ataka; Michio Ohshima; Katuyuki Takahashi
Original assignee: Holon Co., Ltd.
Priority date: 2005-03-15
Filing date: 2006-03-13
Publication date: 2006-09-21
Also published as: JP4505016B2; JPWO2006098266A1

Abstract

A mask cleaning method for cleaning a mask (2), which is loaded in a container such as a magazine (1), before operations such as measurement. Either or both of an operation priority and operation time are specified for a plurality of the masks (2) loaded in the container such as the magazine (1). Based on either or both of the priority and operation time, sorting is performed to decide an operation order. The mask (2) is taken out in the decided operation order, cleaned, transferred to an apparatus main body (5). Then, operation is performed, and after the operation is completed, the mask (2) is transferred and returned to the container such as the magazine (1). Thus, the operation can be performed in the uncontaminated state. The mask (2) can be held not being contaminated even when the mask is loaded in the container such as the magazine (1) for a long time, by cleaning the mask (2) prior to operation each time a prescribed time lapses.

Description

Specification

Mask cleaning method

Technical field

[0001] The present invention relates to a mask cleaning method for cleaning contamination of a mask loaded in a container such as a magazine.

Background art

[0002] In recent years, with mask CD-SEM (a device that inspects the line width of a pattern on a mask using a scanning electron microscope), there are many measurement items, and the measurement time of one mask is 10 times. Many things have exceeded time.

In the past, each mask was set in the apparatus, and when the measurement work was completed, the operator changed the mask and started the measurement work for the next mask. In the defect determination method, if it is impossible to determine the type of defect, the determination is suspended, the search is performed again after re-cleaning, and if the previous detection disappears, it is determined as a foreign object and exists at the same position. If this is the case, there is a technique in which an inspector uses a scanning electron microscope to finally determine the type of defect (Patent Document 1).

Patent Document 1: Japanese Unexamined Patent Publication No. 2003-185592

Disclosure of the invention

Problems to be solved by the invention

[0004] However, as described above, if the measurement time of one mask exceeds 10 hours, automatic replacement of the mask is necessary because the work performed by the operator is extremely inefficient. It became. For this reason, if a plurality of masks to be measured are set in the above apparatus and left for a long time, the mask surface is exposed to contaminants, and the contamination corresponding to the long time adheres to the mask surface. As a result, problems such as excessive measurement error occurred.

In addition, the technique disclosed in Patent Document 1 described above re-cleans when the type of defect cannot be determined, and cannot prevent or remove contamination such as foreign matter in advance. There was a problem.

Means for solving the problem

[0005] In order to solve these problems, the present invention measures a plurality of masks loaded in a magazine or other container after taking out and cleaning them in order of priority and in short measurement time, or when a predetermined time or more has elapsed. Occasionally remove the mask from a magazine or other container, and then hang it back to restore it. The invention's effect

[0006] The present invention makes it possible to measure and hold a mask without contamination even when it is loaded in a container such as a magazine for a long time.

BEST MODE FOR CARRYING OUT THE INVENTION

[0007] In the present invention, when a plurality of masks loaded in a container such as a magazine are measured in order of priority, in a short measurement time, taken in order and cleaned, or when a predetermined time or more has elapsed. The mask in a magazine or other container is taken out, cleaned, and returned to its original position, and the mask can be measured and held for a long time without contamination even if it is loaded in the magazine or other container.

Example 1

FIG. 1 shows a block configuration diagram of the present invention.

In FIG. 1, a magazine 1 is a carrying box in which a plurality of masks 2 fixed to a mask holder 3 are loaded, and the inside of the magazine 1 is sealed so that dust does not enter from the outside.

[0009] The mask holder 3 is a folder that fixes a mask (an original for exposing a pattern on a wafer), and here, an IC tag is attached thereto.

[0010] The preliminary exhaust chamber 4 is a room (sealed space) that is taken out from the magazine 1 and is preliminarily exhausted by entering the mask holder 2 to which the mask 2 is fixed. Here, a cleaning lamp 41 is used. A room with a gas introduction mechanism 42 and the like. When the mask 2 is taken in, pre-exhaust from atmospheric pressure to about 10 3mmTorr, and when discharging, reversely inject air from vacuum to atmospheric pressure. When cleaning, place gas (oxidizing gas (eg air), inert gas (nitrogen etc.)) Introduced to a constant pressure.

The lamp 41 is for removing contaminants by irradiating the surface of the mask 2 with ultraviolet rays, infrared rays, etc. in a state where an oxidizing and inert gas is introduced.

[0012] The gas introduction mechanism 42 introduces gas (oxidizing gas (for example, air, oxygen gas), inert gas (nitrogen, etc.)) to the preliminary exhaust chamber 4 at a predetermined pressure (for example, within 10 to 2 mm TOT). is there.

[0013] The main chamber 5 is a state in which the mask holder 3 to which the mask 2 is fixed is placed on the stage 51. Here, the electron beam probe narrowed down from the electron optical system 6 is planarly scanned, and at that time, the mask Secondary electrons, reflected electrons, light, etc. emitted from the surface of 2 are detected by a known detector (not shown), and an image modulated with the brightness on the display (for example, secondary electrons). This is a room for displaying (image) (vacuum room of 10_6mmTorr or less).

The stage 51 is a mechanism for placing the mask holder 3 to which the mask 2 is fixed and moving it to a predetermined position in any direction (for example, the X direction and the Y direction) with high accuracy.

The electron optical system 6 generates an electron beam, scans the surface of the mask 2 with a focused and narrowed electron beam, and scans the surface of the mask 2 while scanning the secondary electrons generated at that time. Detects and displays a high-magnification image (for example, a secondary electron image) on a display (not shown), magnifies and displays a fine pattern on the mask 2, and automatically measures the width of the pattern at many specified positions. It is for doing.

[0016] The PC 11 is a personal computer that performs various controls according to a program. Here, the PC 11 mainly performs various controls for cleaning the contamination of the mask 2, and includes a priority order determination unit 12, a cleaning control unit. 13 and measuring means 14 etc.

[0017] The priority order determining means 12 is for determining the working order of the plurality of masks 2 loaded in the magazine 1 (to be described later with reference to FIGS. 2, 5, 6, etc.).

[0018] The cleaning control means 13 controls the cleaning of the mask 2 (to be described later with reference to FIGS. 2, 3, 4, etc.).

The length measuring means 14 is a known one that automatically measures the line width and the like of the pattern formed on the mask 2. Next, the overall operation of the configuration of FIG. 1 will be described in detail according to the order of the flowchart of FIG.

FIG. 2 is a flowchart for explaining the operation of the present invention.

In Figure 2, S1 sets the priority. This is because the priority of the work order is set for the mask 2 loaded in the magazine 1, for example, the priority (number with a small number) is associated with the mask name in the priority table of FIG. The higher the priority, the higher) is set.

[0022] S2 sets a magazine. This is because a mask holder with a plurality of masks 2 fixed in a clean room (pre-processing step) (not shown) is loaded into the magazine 1 and then the magazine 1 is transported to the room of the apparatus in FIG. Set automatically at the position shown in the figure.

[0023] S3 starts to be removed from the magazine. This starts taking out the mask 2 (mask 2 fixed to the mask holder 3; the same applies hereinafter) from the magazine 1 set at the position shown in S2.

[0024] S4 sorts in order of priority. This sorts mask 2 loaded in magazine 1 in the priority order set in S1.

[0025] S5 performs re-sorting in consideration of the measurement work time. This is sorted in order of priority in S4, and then re-sorted in consideration of the measurement work time of mask 2, for example, re-sort so that the work time that is significantly shorter is given priority. Specifically, as shown in Fig. 6 (c) described later, in the priority order, the mask name was B → A → C. Re-sort from B to C.

[0026] S6 carries. For this, the first mask 2 in the order determined in S5 is taken out of the magazine 1 and transferred to the preliminary exhaust chamber 4 for preliminary exhaust.

[0027] In step S7, cleaning 1 is performed. This is in accordance with the flowchart of FIG. 3 to be described later. After introducing the gas into the preliminary exhaust chamber 4 at a predetermined pressure, the lamp 41 is turned on and the surface of the mask 2 is irradiated with ultraviolet rays. Remove and clean the contaminants.

[0028] S8 carries. This is because after completing cleaning 1 in S7, preliminary exhaust of the preliminary exhaust chamber 4 is performed again to make the vacuum as high as possible, and then the gate valve between the preliminary exhaust chamber 4 and the main chamber 5 is opened. The mask 2 is placed in the main chamber 5 at the measurement work position shown in the figure. Transport.

[0029] Measurement starts in S9. This is specified on the mask 2 placed on the stage 51 in FIG. 1 (to be exact, the mask 2 placed on the stage 51 with the mask holder 3 placed on the stage 51, and so on). Start length measurement such as the width of the specified location of the pattern.

[0030] S10 ends the measurement. This starts the measurement at S9 and ends the measurement of all locations of all the specified patterns. Usually it takes 10 minutes at the fastest and more than 10 hours at the longest.

[0031] S11 returns to the magazine. This is done by transporting the mask 2 that has been completed in S10 to the preliminary exhaust chamber 4, and then transporting it back to a predetermined position (usually the original position) of the magazine 1. Here, to return to the magazine 1 is, to be precise, for the mask 2 (the mask 2 fixed to the mask holder 3) placed on the stage 51 in FIG. After confirming the vacuum, the gate valve between the preliminary exhaust chamber 4 and the main chamber 5 is opened, the mask 2 is transferred to the preliminary exhaust chamber 4, and then the gate valve is closed. Then, after putting dry air (or dry nitrogen gas) into the pre-exhaust chamber 4 to atmospheric pressure, the gate valve between the pre-exhaust chamber 4 and the magazine 1 is opened, and the mask 2 is transferred to a predetermined position in the magazine 1 Then put it back.

[0032] In step S12, it is determined whether the process is over. This determines whether or not the length measurement work has been completed for all masks 2 in magazine 1. If YES, exit. If NO, return to S4 and repeat for next mask 2.

[0033] As described above, the magazine 1 loaded with the plurality of masks 2 is automatically set (or set by the operator) at a predetermined position in the preliminary exhaust chamber 4 of the apparatus shown in FIG. The control is automatically repeated until the mask 2 is taken out and cleaned in order of priority, and then the operation (in this case, the length measurement operation) is repeated, and the operation is automatically repeated until all operations are completed. Work (automatic length measurement work) can be performed. At this time, prior to length measurement, gas can be automatically introduced to the surface of the mask 2 and measurement can be made after removing contaminants by irradiating ultraviolet rays from the lamp 41. Surface measurement can be performed automatically.

[0034] Although the gas was introduced into the preliminary exhaust chamber 4 and ultraviolet rays were irradiated from the lamp 41 to remove the contaminants on the surface of the mask 2, the inside of another adjacent chamber different from the preliminary exhaust chamber 4 was removed. Contaminant on the surface of the mask 2 by transferring the mask 2 to the gas and introducing the gas and irradiating with ultraviolet rays from the lamp 41 You can even remove it. In this case, the preliminary exhaust chamber 4 of the apparatus is made the same as the conventional one, and a new chamber is provided to introduce a mechanism for introducing the gas and irradiating the surface of the mask 2 with ultraviolet rays from the lamp 41 and an automatic transfer mechanism. This can be realized by simply adding the configuration.

FIG. 3 is a flowchart for explaining the operation of the present invention (cleaning 1). This is a detailed flowchart of the cleaning 1 of S7 in FIG. 2 described above.

In FIG. 3, S21 introduces a gas. In this state, with the mask 2 being transported to the preliminary exhaust chamber 4 in FIG. 1, the preliminary exhaust chamber 4 is once evacuated and then the gas is introduced. As described on the right side,

• Oxidizing gas: oxygen, air, etc.

• Inert gas: argon, nitrogen, etc.

Is introduced to a predetermined pressure (for example, a predetermined pressure from atmospheric pressure to 10-6 Pascal level) or a continuous trace amount is introduced.

[0037] S22 irradiates ultraviolet rays. this is,

• For example, irradiate the surface of mask 2 with a deuterium lamp that emits wavelengths of 400nm or less to 172nm

• For example, irradiate the surface of mask 2 with a YAG laser that generates a wavelength of about 1064 nm.

To do. The irradiation time is set by experimentally determining the time during which the contaminants on the surface of mask 2 can be removed (usually within a range of several minutes to 60 minutes).

[0038] In S23, the cleaning is completed.

As described above, in a state where the mask 2 is conveyed to the preliminary exhaust chamber 4 in FIG. 1, the gas is introduced, and the surface of the mask 2 is irradiated with ultraviolet rays and infrared rays from the lamp 41 and the like. It is possible to gasify and remove contaminants on the surface of the mask 2 and to tally the surface of the mask 2.

FIG. 4 is a flowchart for explaining the operation of the present invention (cleaning 2). This is a detailed description of the process for cleaning the surface of the mask 2 every time a predetermined time or a specified time elapses when the mask 2 loaded in the magazine 1 in FIG. 1 stays for a long time. Show. In FIG. 4, S31 determines whether or not there is a mask 2 that has not been measured and that has passed a predetermined time or more. This is because mask 2 loaded in magazine 1 in FIG. 1 is not measured (unprocessed), and mask 2 is loaded in magazine 1 (or magazine 1 is set in spare non-air chamber 4 or mask 2 Is set on the mask holder 3) and the date and time of the starting point is recorded on the IC tag attached to the mask holder 3 or mask 2 and read out, or the starting point is stored in the hard disk device of PC11 in Fig. 1. It is determined whether or not there is a mask 2 that has passed for a predetermined period of time. If yes, go to S32. If NO, end.

[0041] S32 is taken out. This is done by taking out the mask 2 in S31 YES and transporting it into the spare air chamber 4 in FIG.

[0042] In S33, cleaning 1 is executed. This is done by performing cleaning 1 (S21 to S23) in accordance with the flowchart of FIG. 3 described above to remove contaminants on the surface of the mask 2.

[0043] S34 returns. This is done by removing the contaminant on the surface of mask 2 with cleaning 1 in S33, and then returning the mask 2 to magazine 1.

[0044] S35 determines whether the end. If YES, exit. If NO, repeat S31 and subsequent steps for the next mask 2 loaded in magazine 1.

As described above, after the magazine 1 in FIG. 1 is set in the preliminary exhaust chamber 4, the unworked mask 2 that has passed a predetermined time is transferred to the preliminary exhaust chamber 4 and contaminated on the surface of the mask 2. By removing the material and then returning it, the problem of the surface of the mask 2 staying in the magazine 1 accumulating contaminants over time has been solved, and the surface of the mask 2 is always automatically cleaned. It is possible to hold it.

FIG. 5 shows a flowchart for explaining the operation of the present invention. This shows an example of a detailed flowchart for determining the work order of the mask 2 based on the priority and the processing time.

In FIG. 5, S41 determines whether there is a measurement within 30 minutes. This is, for example, a measurement (operation) set in association with the mask name of the mask 2 set in the magazine 1 in FIG. 1, which is set in the priority table in FIG. Determine if there is a force S within 30 minutes. Within 30 minutes corresponds to a very short working time for the measurement (work) considered here. If YES in S41, proceed to S42. In the case of N〇, Work) Since it was found that there was no mask 2 with a short time, in S43, leave it as it is (in order of priority) and finish.

[0048] S42 determines that the measurement (working) time of the mask 2 is within 30 minutes with YES of S41, and further determines whether the priority is the first. In the case of YES, since the priority is given priority No. 1, it is left as it is in S43 (in order of priority), and the process is terminated. On the other hand, in the case of NO in S42, it was found that the priority was not the first, so it was replaced in S44, that is, the priority of mask 2 that was found to be within 30 minutes, and here the priority of the first priority Swap the priority of mask 2. Specifically, the work order of mask 2 in Fig. 6 (c_l), B → A → C, is changed as A → B → C in (c_2) of Fig. 4 (the order of B and A). Reverse).

[0049] As described above, the mask 2 loaded in the magazine 1 is usually measured (worked) in order of priority, but the mask 2 measurement (worked) time is short (in this case, for example, 30). If the priority is not 1, the mask 2 of the other priority force number is switched in this order, and the measurement (work) is performed first. ), And the mask 2 with a short measurement (working) time is kept waiting for a long time in the magazine 1 and it is possible to eliminate the accumulation of contaminants. For the mask 2 that has not been measured (unprocessed) and stayed in the magazine 1 for a long time, the surface of the mask 2 is cleaned at predetermined time intervals according to the flowchart shown in FIG. Do not allow contaminants to accumulate on the surface of mask 2.

The power S

FIG. 6 shows an explanatory diagram of the present invention.

FIG. 6 (a) shows an example of a priority table. The priority table 7 registers and manages the following information shown in association with the mask name of the mask 2 loaded in the magazine 1 shown in FIG.

[0051] 'Mask name:

•priority:

• Measurement (working) time:

'Other:

Here, the mask name is a unique name for identifying the mask 2 loaded in the magazine 1 in FIG. . The priority is a priority of measurement (work) of the mask 2 identified by the mask name, and indicates that the priority is higher in the order of 1, 2, 3,. The measurement (operation) time is the time (estimated approximate time) required for the measurement (operation) of mask 2 identified by the mask name.

[0052] As described above, by setting the priority and the measurement (working) time in advance for the mask 2 loaded in the magazine 1 in FIG. 1 (set in S1 in FIG. 2 described above), Prioritize measurement (work) for multiple masks 2 in order of priority, or when the measurement (work) time is short (in this case, within 30 minutes) as shown in the flowchart of FIG. Measurement (work) can be performed in a short time, and measurement (work) can be performed quickly without the accumulation of contaminants on the mask 2, which requires only a short measurement (work) time.

FIG. 6B shows an example of a condition table. Condition table 8 sets conditions for performing measurement (work) in preference to the other mask 2 when the measurement (work) time is short.

• Is there a measurement within 30 minutes?

Is set in S41 in Fig. 5 described above, and measurement (work) of mask 2 within 30 minutes can be preferentially executed (see the flowchart in Fig. 5 and its explanation). reference).

FIG. 6C shows an example of replacement. This is based on the priority table 7 in FIG. 6 (a) and the flow chart in FIG. 5 in which the conditions in the condition table 8 in FIG. 6 (b) are set. Only in order of priority, it is shown in (c 1) of Fig. 6.

• B → A → C

Perform measurements (work) in the order of

• If the measurement (work) time is within 30 minutes and the conditions for preferential measurement (work) (condition (b) in Fig. 6) are set, the flow chart shown in Fig. 6 (c_ 2) Show

A → B → C

It becomes.

[0055] As described above, when there is mask 2 with a short measurement (work) time (here, within 30 minutes set in condition table 8 in Fig. 6 (b)), measurement (work) is given priority. ) To prevent contaminants from accumulating on the surface of the mask 2 that takes the short measurement (work) time. Measurement (work) quickly.

FIG. 7 shows an example of the IC tag and IC tag information of the present invention.

FIG. 7 (a) shows an example in which an IC tag is attached to the mask holder 3. FIG. The IC tag 9 can read and write data wirelessly, and is attached to the mask holder 3 here. The IC tag 9 may be directly attached to the back surface of the mask 2 or the like.

FIG. 7B shows an example of information recorded on the IC tag 9. The following information shown in the figure is read and written to the IC tag 9 wirelessly.

[0058] -ID:

'Mask name:

• Date:

'Date and time set in Mask Honoreda 3:

• Date and time when mask 2 was set in magazine 1:

• Date and time set in the device

• Date and time of washing

'Other:

Here, the ID is an ID that uniquely identifies the IC tag 9. The mask name is the mask name of mask 2 with IC tag 9 attached. The date and time are the date and time when mask 2 was set in mask holder 3, the date and time when mask 2 was set in magazine 1, the date and time when magazine 1 was set in the device (device in Fig. 1), and the date and time when mask 2 was cleaned (washed). It is.

[0059] As described above, the IC tag 9 is affixed to the mask 2 (or the mask holder 3 to which the mask 2 is fixed) to be loaded in the magazine 1, and the mask name and date / time are written, as shown in FIG. In addition, when magazine 1 is set at the position shown in the figure, information (mask name and date / time) of mask 2 loaded in the magazine 1 is read out, and in order of priority, and further, measurement (work) time It is possible to measure (work) with priority on the shortness of items. At this time, cleaning is performed immediately before the measurement (operation) and the surface of the mask 2 is cleaned for measurement, or when the mask 2 stays in the magazine 1 for a predetermined time or more (or every time it stays for a predetermined time or more). The surface of the mask 2 can be automatically kept clean by taking it out and returning it to the tare (cleaning, see Fig. 4). [0060] Although the case where the mask 2 stays in the magazine 1 is cleaned (Fig. 5), the mask 2 in the magazine 1 is moved to another room (container) and held (stayed). Similarly, the present invention can be applied to the cleaning of contaminants deposited on the surface of the mask 2 in another room when the mask 2 is sequentially taken out from another room and measurement (operation) is performed. is there.

Industrial applicability

The present invention relates to a mask cleaning method for measuring and holding a mask without contamination even when the mask is loaded into a container such as a magazine for a long time.

Brief Description of Drawings

FIG. 1 is a block configuration diagram of the present invention.

FIG. 2 is a flowchart for explaining the operation of the present invention.

FIG. 3 is a flowchart for explaining the operation of the present invention (cleaning 1).

FIG. 4 is a flowchart for explaining the operation of the present invention (cleaning 2).

FIG. 5 is a flowchart for explaining the operation of the present invention.

FIG. 6 is an explanatory diagram of the present invention.

FIG. 7 is an example of an IC tag and IC tag information according to the present invention.

Explanation of symbols

[0063] 1: Magazine

2: Mask

3: Mask Honoreda

4: Preliminary exhaust chamber

41: Lamp

42: Gas introduction mechanism

5: Main chamber

51: Stage

6: Electron optics

7: Priority table

8: Condition table C tag

: PC

: Priority order determining means: Cleaning control means: Length measuring means

Claims

The scope of the claims

[1] Mask cleaning method for cleaning contamination of masks loaded in magazines and other containers Sorting multiple masks loaded in magazines and other containers based on priority and / or working time Step to determine the work order,

Taking out the mask in the order of the determined work, transporting it to the apparatus body or cleaning it and then transporting it to the apparatus body, and executing the work;

A mask cleaning method comprising: transferring a mask to a container such as the magazine when the operation is completed.

[2] Among the masks loaded in a container such as the magazine, the method includes a step of removing the unfinished mask when a predetermined time elapses or after each predetermined time elapses and returning it to the magazine or other container. The mask cleaning method according to claim 1, wherein the mask cleaning method is characterized in that:

[3] The cleaning of the mask is performed by irradiating the surface of the mask with ultraviolet rays or infrared rays with an oxidizing gas or an inert gas being introduced in the vicinity of the mask to remove contaminants attached to the surface of the mask. The method for cleaning a mask according to claim 1 or claim 2, wherein:

[4] Affix an IC tag that reads / writes wirelessly to the mask holder that holds the mask or to the mask itself, and stores one or more of the priority, the work time required for the work, and the cleaning time for washing. The mask cleaning method according to any one of claims 1 to 3, wherein: