JP2777801B2 - Pattern film repair method in focused ion beam device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of repairing a pattern film in a focused ion beam apparatus, and more particularly to a method of repairing a pattern film that can perform an accurate operation even when a defective portion cannot be recognized. It is.

[Summary of the Invention] Compound gas is sprayed on a sample on a stage by a gas gun to attach the compound in order to improve and advance the technology of forming a pattern film with the recent increase in the scale and integration of semiconductor devices (LSIs). In performing a defect correction of the pattern film formed by focusing and irradiating the ion beam on the sample surface by the ion beam irradiation optical system, a spot hole processing is performed by the focused ion beam in the vicinity of the defect portion of the pattern film,
Recognition of a defective portion and a positional relationship between the defective portion and a dot hole are obtained from a signal of the secondary ion, and a necessary correction is performed on the defective portion.

[Prior Art] In recent years, one of the backgrounds for increasing the scale and integration of semiconductor devices (LSIs) is the remarkable development of LSI manufacturing technology. F is one of the LSI manufacturing technologies
There is IB (focused ion beam) technology, and this FIB technology is not only a depiction technology but also a processing technology, and it is now possible to recognize and correct defects in the pattern film of LSI circuits. That is, when the focused ion beam is irradiated and scanned on the sample on which the pattern film is formed, secondary ion particles are emitted from the sample. The secondary ions include secondary ions from the sample (for example, Si from the glass substrate) and secondary ions from the pattern film (for example, Cr from the chromium film). By analyzing the amounts of Si and Cr, the edges of the pattern film can be detected, and defects in the pattern film can be recognized. This defect includes a black defect in which extra Cr remains when a photomask is formed, and a white defect in which Cr is missing. When correcting a black defect, the black defect portion is etched, while when correcting a white defect, a compound gas is sprayed on the portion, and a focused ion beam is irradiated to carbonize the organic film.

FIG. 4 is a view showing a conventional pattern film correcting method for a pattern film having such a black defect or a white defect. In this figure, reference numeral 1 denotes a pattern film,
Reference numeral 2 indicates a black defect, and reference numeral 3 indicates a white defect. There are various types of defects in the pattern film 1, for example, FIG. 4 (a)
As shown in FIG. 4, when a black defect 2 and a white defect 3 are continuously present on one side of one edge 1a of the pattern film 1, as shown in FIG.
1b, a black defect 2 and a white defect 3 are formed at substantially the same position in the length direction of the pattern film 1, and one edge of the pattern film 1 as shown in FIG. In some cases, a black defect 2 and a white defect 3 on the other edge 1a are formed at a certain distance L from each other in the length direction of the pattern film 1 in some cases. Of course, in the case of FIG. 4 (b) or (c), there may be a case where only the black defect 2 or only the white defect 3 is formed at both edges 1a and 1b of the pattern film 1. In the case where such defects are present in the pattern film 1, the focused ion beam apparatus first searches for the presence of the defect 2 or 3 in the pattern film 1 in the observation operation mode, When it is found that the defect 2 or the white defect 3 exists, the sample is moved by driving the stage, and the defect portion is brought within a range scanable by the ion beam. And the defect is corrected. When correcting the black defect 2, the focused ion beam apparatus recognizes the shape of the black defect 2 in the previous observation mode, and etches the region of the black defect 2 based on the recognition.
When correcting a white defect, a compound gas is sprayed onto a necessary portion of the white defect based on the shape or the like of the white defect recognized in the observation mode, similarly to the case of correcting the black defect 2. The white defect 3 is corrected by irradiating an ion beam and masking, for example, carbonizing the organic film. Correction of such a defect 2 or 3 is shown in FIGS. 4 (a), (b),
(C) is performed for any of the defect modes.

[Problems to be Solved by the Invention] However, in such a conventional method for repairing a pattern film, the focused ion beam device recognizes the shape of the black defect 2 or the white defect 3 and performs etching or etching according to the recognition. Since the masking is performed, various inconveniences may occur during the repair work of the pattern film 1. That is, for example, if there is a black defect 2 and a white defect 3 and the black defect 2 is etched first, during the etching operation, it is assumed that Cr is scraped off by ion beam irradiation. A phenomenon occurs in which the material of the pattern film 1 scatters around and deposits, for example, on a relatively close white defect portion. For this reason, when the masking operation of the white defect 3 is performed after the black defect 2 is corrected, the Cr scattered from the portion of the black defect 2 accumulates on the portion of the white defect 3 and the white defect 3 is removed. May have blurred edges. In this case, it becomes difficult to recognize the shape of the white defect 3, and it becomes very difficult to irradiate and scan the ion beam, so that there is a problem that the correction of the white defect 3 becomes difficult. For this reason, conventionally, after the black defect 2 is corrected, as shown in FIG. 4C, a focused ion beam is scanned in the area A surrounding the white defect 3,
After performing cleaning to remove stains due to sputtered particles and clarifying the edge of the portion of the white defect 3 to some extent, a masking process for the white defect 3 is performed.
That work was being done. However, when such an operation for removing sputtered particles by scanning with the ion beam is performed, the edge portion of the white defect 3 is also cut off to some extent, and the ion beam is irradiated on the sample surface other than the portion of the pattern film 1. In other words, the scanning is also performed on the glass substrate, whereby ions are implanted into the glass surface, and the transmittance of the glass is reduced, thereby causing a problem that the correction accuracy of the pattern film 1 is deteriorated. . Therefore, conventionally, as shown in FIG.
The substrate itself was rejected for the pattern film 1 in which 3 was present, because it was difficult to correct the pattern film. In addition, the pattern film 1 having the defects 2 and 3 as shown in FIG.
Can be corrected, but the result of the correction has been subjected to manufacturing control from the viewpoint of poor reliability.
It has been recognized that only the pattern film having the defects 2 and 3 as shown in FIG. 4C can be corrected to some extent with reliability.

The present invention has been made in view of such conventional problems, and its object is to provide a highly reliable and accurate method even when various defects exist in the pattern film. An object of the present invention is to provide a pattern film correcting method capable of correcting a pattern film.

Means for Solving the Problems In order to achieve the above object, the present invention irradiates a sample gas on a sample with a gas gun with a gas gun, and irradiates the compound gas attached on the sample with an ion beam.
In a focused ion beam apparatus that forms a pattern film and that can display the formed pattern film,
When correcting a defect of the pattern film, a spot hole processing is performed by a focused ion beam in the vicinity of the defect portion of the pattern film, a positional relationship between the defect portion and the point hole is obtained by a signal of the secondary ion, The gist is a method of correcting a pattern film in which a necessary correction is performed while determining the position of the pattern film.

[Operation] In forming a pattern film, a compound gas is blown onto a sample by a gas gun, and the compound gas is attached to the sample. The attached gas is irradiated with an ion beam by an ion beam irradiation optical system to form a pattern film. In the step of forming the pattern film, an electron beam is irradiated onto the sample from the electron gun, and charge-up of the sample surface by the ion beam is prevented. When the pattern film is formed in a predetermined shape in this way, the focused ion beam apparatus is switched to the observation mode, and the pattern film is ground for any defects. When it is detected that the pattern film has a defect, the focused ion beam apparatus recognizes whether the defect is a black defect or a white defect, and determines how large the range of those defects is ( Area). After that, the focused ion beam apparatus is switched to the pattern film repair mode, and in the first stage of this mode, firstly, a defect to be repaired is specified, and this defect is placed in the field of view of the focused ion beam apparatus. In addition, a hole is drilled in the pattern film near the defect. When the dot hole is formed, the control device in the ion beam device, that is, CP
U calculates by calculation the type of defect, that is, whether it is a black defect, whether it is a white defect, the size of the defect, and the positional relationship between the previously formed dot hole and the defect. Store all data related to In the next stage, the focused ion beam device performs pattern film correction. In this correction execution stage, while reading out position data and the like relating to the defect, the area of the black defect is etched if it is a black defect, and the masking correction processing is performed on the range of the white defect if it is a white defect. Therefore, in the case where a plurality of defects are present at relatively close positions, even if contamination of another defect portion due to sputter particles generated when one of the defects is corrected occurs, the control unit firstly performs Since the defect is repaired at a certain position and range while reading the stored position information of the defect, accurate defect correction can be performed even if the edge of the defective portion is unclear.

[Embodiment] FIGS. 1 to 3 are views showing an embodiment of a focused ion beam apparatus used for executing a pattern film correcting method of the present invention and an operation example thereof. The focused ion beam apparatus according to this embodiment includes an XY stage 10 provided at a lower position inside the vacuum chamber 7 and supporting the sample 4, an ion source 8 provided at an upper end portion of the vacuum chamber 7, Condenser lens for focusing the ion beam irradiated from the source 8
11, a blanking electrode 19 provided at a position behind the condenser lens 11, an objective lens 12 for focusing the ion beam 5 focused by the condenser lens 11 on the sample 4, and an ion beam 5 on the sample 4. Scanning electrode 13 and gas gun 14 for spraying compound gas onto sample
And an electron gun 6 for spraying charge-up neutralizing electrons onto the sample 4, and a secondary ion detector 15 for detecting secondary ions 4a emitted from the surface of the sample 4 by irradiation of the ion beam 5. And comprising. The ion source 8, the condenser lens 11, the objective lens 12, the scanning electrode 13, and the blanking electrode 19 constitute an ion beam irradiation optical system that focuses and irradiates the sample 1 on the XY stage 10 with the ion beam 5. I have. The secondary ion detection signal created by the secondary ion detector 15 is sent to the A / D converter 16,
Then, it is sent to the display unit 17 to display the surface structure of the sample 4. The operation of the A / D converter 16 and the display unit 17 is controlled by a CPU 18 constituting a control unit. The CPU 18 includes the ion source 8, the condenser lens 11, the blanking electrode 19, the objective lens 12,
The operation of the ion beam irradiation optical system constituted by the scanning electrode 13 is also controlled.

The operation of correcting the pattern film by the focused ion beam apparatus having such a configuration will be described. Fig. 2 (a)
The black defect 2 is formed at the edge 1b of the pattern film 1, the white defect 3 is also present at the edge 1a of the pattern film 1, and the black defect 2 and the white defect 3 are relatively close to each other. FIG. 3 shows a case where the focused ion beam device is in the same field of view. FIG. 3 (a) shows a procedure of a correction processing operation of the pattern film 1 in this case. When correcting the pattern film in the case where the black defect 2 and the white defect 3 exist in the same visual field, the CPU 18 determines in the processing step ST1 that a dot hole is formed in one place near both the defects 2 and 3. Apply processing. This dot hole processing is performed by continuously irradiating an ion beam to one point of, for example, chromium Cr forming the pattern film 1, whereby a dot hole 20 is formed in a portion of the Cr ion beam irradiated, and only at that position, The glass substrate as a sample becomes visible. When the dot hole 20 has been formed, the CPU 18 switches the focused ion beam apparatus to the observation mode, and recognizes the relative positions of the dot hole 20, the black defect 2 and the white defect 3 in a processing step ST2, and stores the positional relationship between them. To memorize. Furthermore, CPU18
In this processing step ST2, the pattern shape of the black defect 2 and the pattern shape of the white defect 3 are recognized, and the respective shapes are stored in the memory. Next, in the processing step ST3, the CPU 18 starts preparation for processing the black defect 2 or the white defect 3. In this embodiment, it is assumed that the processing starts with the processing of the black defect 2 first. When the preparation for processing is completed, CP
U18 checks the dot hole 20 in the processing step ST4, reads the data from the memory to check the position of the black defect 2, and performs an etching process on the black defect 2. When the etching process in the processing step ST4 is completed, the CPU 18 starts preparing for processing the white defect 3 in a processing step ST5. In starting the processing of the white defect 3, the CPU 18 confirms the position of the dot hole 20 in the processing step ST6 in the same manner as described above, and confirms the position of the white defect 3 by reading data from the memory. The data relating to the pattern shape of the white defect is also read out and the preparation for processing is completed. Then, the CPU 18 proceeds to the next processing step S
At T7, the masking processing of the white defect 3 is performed. When the masking process for the white defect 3 is completed, a series of processes for correcting the pattern film by the focused ion beam device is completed.

FIG. 2 (b) shows a case where a black defect 2 and a white defect 3 exist at relatively distant positions on the pattern film, and these two defects 2 and 3 exist outside the same field of view of the focused ion beam apparatus. Is shown. FIG. 3 (b) is a diagram for explaining the correction processing operation of the pattern film 1 in this case. As described above, when two or more defects exist outside the same field of view, the CPU 18 puts the focused ion beam device into the observation mode in the processing step ST11, and firstly removes one defect, for example, the white defect 3. It is set within the field of view of the focused ion beam apparatus, and thereafter, the mode is switched to the point hole processing mode, and a point hole 21 is formed near the white defect 3. When the machining of the dot hole 21 is completed, the CPU 18 stores data on the relative position between the dot hole 21 and the white defect 3 and the shape of the white defect 3 in the memory in the next processing step ST12. When this processing is completed, in processing step ST13, the CPU 18 switches the focused ion beam device to the observation mode, moves the stage, and puts the black defect in the field of view. When the black defect 2 enters the field of view, the CPU 18 proceeds to the next processing step ST14.
In, a spot hole 22 is formed near the black defect. When the dot hole 22 is formed, the CPU 18 proceeds to the next processing step S
At T15, data on the relative position between the dot hole 22 and the black defect 2 and the pattern shape of the black defect 2 are stored in the memory. If there are a plurality of defects other than the black defect 2 and the white defect 3, the CPU 18 proceeds to the processing step 13.
Steps 15 to 15 are sequentially repeated to form spot holes corresponding to the number of defects. When the formation of the dot holes 21 and 22 is completed, the CPU 18 prepares for the masking processing for the white defect 3 in the next processing step ST16. Then, in the next processing step ST17, the positional relationship between the dot hole 21 and the white defect 3 is confirmed, and the data on the pattern shape of the white defect 3 is read from the memory.
In ST18, a masking process is performed on the white defect 3. When the masking processing for the white defect 3 is completed, the CPU 18 drives the stage 10 in a processing step ST19, and starts preparing for the correction processing of the black defect 2 in the next processing step 20. Next, the CPU 18 executes the processing step 21
After confirming the positions of the dot hole 22 and the black defect 2,
Data relating to the pattern shape of the black defect 2 is read from the memory, and etching processing is performed on the black defect 2 in the next processing step ST22. When the etching process for the black defect 2 is completed, a series of pattern film correcting operations is completed. When there are a plurality of defects other than the black defect 2 and the white defect 3, the CPU 18 performs the processing steps ST16 to ST16.
The processing operation of T19 is repeated, and the correction processing for each defect is performed. In this way, by the processing operation of the CPU 18, the dot holes 20, 21, and 22 are formed in the pattern film, and based on these dot holes, the position of the black defect 2 or the white defect 3 is determined. The pattern shapes of the defects 2 and 3 are also stored, and based on the stored data, the defects 2, 3
For example, even if spatter particles are scattered by the previous defect repair work and other defect parts are stained, correction for the next defect is almost completed. Processing can be performed, and extremely accurate pattern film correction becomes possible. Therefore, although not described in the above embodiment, even if there are continuous defects as shown in FIG. 4 (a) in the pattern film 1, these defects 2 and 3 can be corrected without inconvenience. .

[Effects of the Invention] As described above, according to the present invention, when correcting a pattern film using a focused ion beam apparatus, a spot hole is formed by a focused ion beam in the vicinity of a defect portion of the pattern film. Since the positional relationship of the defective portion is calculated based on the reference, and the defective portion is corrected based on the position data, for example, the defective portion should be corrected later by sputter particles when another defective portion is corrected. Even if the defective part is contaminated, accurate defect correction can be performed.Also, as in the past, after one defect is corrected, before another defect is corrected, the other defect can be corrected. Since it is not necessary to perform processing such as cleaning on the portion, useless work procedures can be omitted, and work time for correcting the pattern film can be reduced. Furthermore, since the sample, for example, the glass substrate does not deteriorate due to the cleaning, various effects can be obtained, such as providing a high quality pattern film after forming and correcting the pattern film. .

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a focused ion beam apparatus used for executing a pattern film correcting method according to the present invention.
FIG. 3 is a view showing a state of existence of a defect in a pattern film to which the pattern film repair method of the present invention is applied. FIG. FIG. 4 is a flowchart showing a processing operation procedure, and FIG. 4 is a view similar to FIG. 2 showing an example of various types of defects existing in the pattern film and an execution example of a conventional pattern film correcting method for these defects. DESCRIPTION OF SYMBOLS 1 ... Pattern film, 2 ... Black defect 3 ... White defect, 4 ... Sample 5 ... Ion beam, 6 ... Electron gun 7 ... Vacuum chamber, 8 ... Ion source 11 ... Condenser lens, 12 … Objective lens 13 Scan electrode 14 Gas gun 15 Secondary ion detector 16 A / D converter 17 Display section CPU CPU 20,21,22

Claims (1)

(57) [Claims] A stage for driving a sample in X and Y directions;
An ion beam irradiation optical system that focuses and irradiates the sample on the stage with a focused ion beam; a gas system that blows a compound gas onto the sample to be irradiated with the focused ion beam; An electron gun that irradiates the electron beam, a detector that detects secondary charged particles emitted from the sample by the focused ion beam irradiation, and a secondary charged particle detected by the detector. A display unit for displaying the formed pattern film two-dimensionally, recognizing a defect of the pattern film,
In the method of repairing a pattern film using a focused ion beam device for repairing the defect, when the defect of the pattern film is repaired, the location, type and shape of the defect are obtained and stored in advance, and the defect portion of the pattern film is stored. A focused ion beam characterized by performing point hole processing in the vicinity with a focused ion beam, obtaining a positional relationship between a defective portion and a point hole by a signal of the secondary charged particle, and thereafter performing necessary defect correction. A method for correcting a pattern film in an apparatus.