JPH0794512A - Wiring forming method and device - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the throughput and the repair yield of the focused ion beam induced deposition method used in the pattern repair and wiring repair process of large scale integrated circuits. In a step of depositing a conductor layer such as wiring by a focused ion beam induced deposition method, a groove is formed in advance in accordance with a desired shape of the conductor layer, and then the conductor layer is deposited in the groove. For example, under the condition that a gas for forming a conductor layer is supplied onto a substrate, a monovalent Ga focused ion beam is first adjusted to the shape of the conductor layer at a current density of a sputtering speed higher than the speed at which the conductor layer is deposited. Irradiation (scanning) is performed to form a groove.
Then, the current density is switched to the deposition rate of the conductor layer which is higher than the sputtering rate to deposit the conductor layer in the groove. [Effect] Since the sputtered particles are taken into the deposited film by forming the groove, the formation speed of the conductor layer is improved, and the deformation of the neighboring pattern due to the reattachment of the sputtered particles can be avoided, and the risk of short circuit with the existing wiring is reduced. And the yield is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a conductor layer by a focused ion beam induced deposition method and an apparatus for forming the conductor layer, and particularly to the formation of wiring conductors or detection electrodes for logic correction of large scale integrated circuits and defect detection. The present invention relates to a wiring forming method and an apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, wiring modification using a focused ion beam induced deposition method has been used for the development of high density integrated circuits. This is the wiring cutting by focused ion beam sputtering and the chemical vapor deposition method (Chemical Vapor Deposition).
Wiring formation by focused ion beam induced deposition, which is performed by irradiating a focused ion beam in the presence of a gas that forms a wiring conductor by ion: CVD, can be performed in the same device while observing secondary electron images. Because it was suitable. Regarding the defect detection of the logic circuit applying this, for example,
"The Japan Society for the Promotion of Science Application of charged particle beams to industry 13th
2 Committee 101st Workshop Material "pp40-45", "IC operation analysis by focused ion beam and wiring change".

The American Vacuum Society, Journal of the
Vacuum Science and Technology, Bee Vol. 9, No. 5, pp. 2670-2674, 1991 [Jour
nalof Vacuum Science and Technology B, Vol.9, No.
5, Sep / Oct 1991 pp2670-2674] describes the case where the mask for X-ray lithography is repaired by the focused ion beam induced deposition method, and the deposition film is sputtered and attached to the existing pattern around the repaired pattern. It points out that it will occur.

[0004]

The problems of the prior art of this kind have the following two problems. That is, the first problem is that the deposition rate of the conductive film is slow and the throughput of wiring modification cannot be increased. In focused ion beam induced deposition, film deposition and sputtering of the deposited film proceed simultaneously. Therefore, the effective deposition rate becomes a low value obtained by subtracting the sputter rate from the deposition rate. Also, the second
The problem of is that the reattachment of sputtered particles scattered near the deposition pattern is not considered, especially when forming a conductor layer such as a circuit correction wiring or a circuit inspection electrode close to the existing wiring. That is, there was a risk of deformation of wiring and short circuit.

Therefore, the problem to be solved by the present invention is to solve the above two problems, namely, a low deposition rate,
And to eliminate the risk of short circuit of adjacent wiring due to redeposition of sputtered particles. That is, a first object of the present invention is to provide an improved wiring formation method by a focused ion beam induced deposition method, which is rapid and has a high yield.
A second object is to provide an improved device for forming it.

[0006]

The first object of the present invention is to provide a wiring forming method, for example, when forming wiring for circuit correction or circuit inspection between existing wirings of an integrated circuit by a focused ion beam induced deposition method. This is achieved by forming a groove in advance in the wiring formation region in accordance with the desired wiring shape and then depositing a conductor layer of, for example, tungsten or molybdenum in the groove. As a method of forming the groove, various methods can be selected according to the purpose as described below.

The first method is to perform groove formation with a high current density beam having a high processing rate and film deposition after gas introduction with a low current density beam having a high deposition rate. That is,
In the first groove formation step, the current density of the ion beam is set to a sputtering rate condition that is higher than the deposition rate, and in the step of depositing the conductive layer in the groove, the deposition rate condition that is higher than the reverse sputtering rate is set, and the current density is switched appropriately. By controlling, the groove forming step is performed prior to the conductive layer depositing step. Thus, the groove formation and the subsequent deposition of the conductive layer in the groove can be continuously performed only by controlling the current density to a predetermined condition, and the wiring formation speed can be dramatically improved. The gas for forming the conductive film is
It is general that it is not flown during the groove forming step but only during the film depositing step, but it may be continued from the groove forming step to the film depositing step. Here, switching of the current density is not essential, but it is an important factor for improving the wiring formation speed. Further, by switching the current density, it is possible to switch between groove formation and embedding without turning on / off the gas introduction.

Further, instead of switching the current density, the residence time of the ion beam may be controlled. During the groove forming process, the scanning speed of the ion beam is slowed down so that the residence time is long and the sputtering is predominant. On the contrary, if the scanning speed is made faster and the stay time is made longer and the deposition is dominant, the groove formation and the deposition of the conductive layer in the groove are continuously performed in the same chamber as in the case of controlling the current density. It can be carried out.

The second method is a case where a higher processing speed or a higher selection ratio with respect to the substrate material is required, and focused ion beam induced etching is used instead of the sputtering in which the current density is increased in the first method. This is a method of forming grooves. That is, in this method, the reactive gas species are switched instead of controlling the current density, and during the first groove forming step, an etching gas suitable for the material of the groove forming region is supplied to scan the focused ion beam. By doing so, a predetermined groove is formed, then the reaction gas is switched to a gas for forming a conductive layer, and the inside of the groove is scanned again with a focused ion beam to deposit a predetermined conductive layer. It is necessary to switch the reaction gas, but it is easy to select a gas type suitable for groove formation, and it is effective when you want to further increase the processing speed and when a selection ratio to the substrate material is required. .

The third method is a method of forming a groove in advance by a processing method using conventional lithography. The conventional processing using lithography requires mask making and etching steps, which increases the processing time but is suitable for mass production. In this case, it is possible to shorten the wiring formation time by forming grooves in all the places where wiring is supposed to be formed.

In the wiring forming method by the focused ion beam induced deposition method of the present invention for forming a new circuit wiring between the existing wirings of this type, particularly, a circuit requiring a logic change and some functions are newly added by the wiring change. It can be applied not only to inspection wiring but also to formation of practical wiring in an integrated circuit that can be realized, and can simplify the manufacturing process and shorten the manufacturing period when manufacturing a small amount of a wide variety of integrated circuits from the same original circuit. You can

In the wiring forming method according to the present invention, the larger the ratio of the depth d to the opening width w of the groove (aspect ratio = d / w), the greater the effect of confining the sputtered particles in the groove. And the influence of scattering to the surroundings is reduced, but if the aspect ratio is made extremely large, the flux of the reaction gas entering the groove becomes small, so the reaction gas cannot be supplied in time and wiring is formed in reverse. The speed decreases. This is remarkable especially near the bottom surface.
Also, the groove formation speed tends to decrease at high aspect ratios, and from this point too, extremely large aspect ratios are disadvantageous. Although it depends on the gas pressure on the surface and the absolute value of the groove opening width, the preferable aspect ratio is often 0.5 to
It is 4.5, and particularly preferably 1.5 to 2.5. Looking at the groove width, I want at least 0.3 μm. 0.5 ~
If the thickness is about 1.0 μm, the deposition can be performed at a sufficiently practical speed. Note that the wiring forming method mentioned here means not only the wiring for circuit correction or the circuit inspection as described above but also the formation of a signal extracting electrode from the lower wiring for inspection.

The second object is to improve the beam focusing optical system of the conventional focused ion beam apparatus, and by the wiring forming apparatus which can automatically perform the wiring forming process which is the first object achieving means, To be achieved. That is, a means for extracting an ion beam from a liquid metal ion source, having a desired current density with a focusing optical system, and focusing the beam to a desired beam diameter, and deflecting the focused ion beam to form wiring on a sample A means for scanning according to a wiring pattern to be formed on the area, a means for supplying a reaction gas onto the sample placed on the stage, and a secondary electron in the scanning area for detecting secondary electrons generated by the ion beam scanning. A means for displaying an image, a control device for controlling at least the ion beam deflection system, a current density of an ion beam scanned according to a wiring pattern shape, a current density for forming a groove which is dominant in sputtering and a current for forming a conductive layer which is dominant in deposition. Current density control means for switching to the density and controlling the current density to a desired value to form a groove and subsequently deposit a conductive layer in the groove. The wiring forming apparatus using a focused ion beam induced deposition comprising configured to perform continuously in the same chamber, is achieved.

As the liquid metal ion source, for example, a well-known ion source of Ga, In or the like, which easily becomes a liquid near room temperature, is used. Further, instead of the current density control means for switching the current density of the ion beam between the current density for forming grooves, which is dominant in sputtering, and the current density for forming conductive layers, which is dominant in deposition,
As a means for controlling the beam dwell time by switching the ion beam scanning speed, there are two conditions: a sputter-dominant condition where the scan speed is slow and the dwell time is long, and a deposition condition where the scan speed is fast and the dwell time is short. It can also be a means for setting.

As the current density control means, a lens voltage control unit connected to the focusing optical system is set to a desired value, or an aperture selecting mechanism provided between the focusing optical system and the beam deflecting system can be easily controlled. Is configured. The aperture selection mechanism is a mechanism that can select the required one from the apertures having several kinds of diameters, and determines the absolute value of the beam current. Further, as a means for deflecting the focused ion beam, a beam deflection system is provided between the sample and the focusing optical system, and is configured so that it can be controlled to a desired scanning speed. As means for controlling this scanning speed,
A control device for controlling the beam deflection system is provided, and the dwell time of the ion beam can be easily controlled to a predetermined time by switching the scanning speed.

Further, this control device controls the aperture selection mechanism for selecting an aperture having a desired shape, controls the reaction gas supply means, and controls the opening / closing of the supply valve as necessary, for example, forming a groove. The valve is closed to stop the gas supply for forming the conductive film, and the valve is opened at the start of the deposition of the conductive film to supply a predetermined amount of gas onto the sample. In addition, if it is desired to supply an exclusive gas for etching when forming the groove with this control device, the etching gas is supplied, and when the conductive film is formed, the reaction gas for forming the conductive film is switched to the reaction gas on the sample. It can also be made available.

[0017]

First, the deposition rate of the conductor layer (hereinafter, also referred to as a conductive film) in the wiring forming method which is the first means for achieving the purpose will be described first. The deposition rate of the conductive film of the focused ion beam induced deposition method in the groove is higher than that in the case of depositing on a flat surface. This is because sputtered particles from the deposited film are scattered to the outside in film deposition on a flat surface or a convex portion, so that the film formation rate is low, but by depositing in the groove, sputtering from the film being deposited This is because the particles adhere to the inner wall of the groove and are taken into the deposited film as the groove is filled. In particular, when the deposition is performed inside the groove having a high aspect ratio, the probability of reattachment of sputtered particles to the inner wall of the groove is increased, so that the wiring forming speed is improved several times as compared with the case of a flat surface.

The problem of the deformation and short circuit of the existing wiring in the vicinity due to the reattachment of the sputtered particles can be basically solved by preventing the sputtered particles of the conductive film for wiring from scattering around when forming the wiring correction pattern. For this purpose, a wall-shaped structure for preventing scattering around a newly formed pattern may be formed in advance and then film deposition may be performed, but there is no room for forming a wall-shaped structure in a high-density wiring pattern. This is usually difficult, and if focused ion beam induced deposition is used to form the wall-like structure, spattering of the sputtered particles is inevitable in the process. Therefore, the easiest way is to form a groove between the existing wirings and form the wiring inside the groove. By forming the groove structure, this inner wall serves as a structure for preventing spattered particles from scattering, and it is possible to prevent deformation and short circuit due to redeposition of sputtered particles on an existing wiring pattern adjacent thereto. Moreover, since the sputtered particles used to form the groove are an insulating material such as an interlayer insulating film that is different from the deposited conductive film, there is no risk of short circuit even if they adhere to the surroundings.

The operation mechanism of the wiring forming apparatus, which is the second means for achieving the purpose, will be described. The coordinate data of the area where the wiring is formed is input to the control apparatus while observing the secondary electron image of the display apparatus. Process conditions necessary for sputter processing and conductive film deposition are input in advance to the control device so that optimum beam scanning conditions can be obtained based on the input coordinate data. In the actual wiring formation, the current density of the ion beam is switched between the sputtering process and the conductive film deposition, or the beam deflection system is controlled to switch the ion beam residence time. That is, sputter processing is performed with slow beam scanning (long beam stay time), and after this, the gas supply system is operated to introduce reaction gas, the beam deflection system is controlled, and fast beam scanning (short beam stay time) is performed. Conductive film deposition is performed. Any means is effective in improving the throughput of wiring formation. When such a device is used, the process conditions of groove formation and film deposition are automatically switched, so that there is no human error and the work can be performed quickly, so that the yield and throughput can be improved. .

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. <Embodiment 1> This embodiment shows an embodiment which also serves as a principle explanation of the wiring forming method by the focused ion beam induced deposition method of the present invention. The wiring forming speed in the case of performing it will be described in comparison with the case of forming the wiring on a plane without forming a conventional groove.

FIG. 1 is a sectional view showing a process flow for forming wiring by forming a groove and then by focused ion beam induced deposition. FIG. 1A shows a process of first forming a groove 2 in an insulating film 1 by focused ion beam sputtering. In this embodiment, first, a groove is formed by a focused ion beam 3 having a beam current of 5 nA and a beam diameter of 0.5 μm. The ions were monovalent Ga ions, and the acceleration energy was 30 keV. Groove width is about 0.7μ at the opening
m, the depth was about 1 μm, and the length was about 50 μm. This groove formation process took about 30 seconds.

Next, FIG. 1 (b) shows a process of forming a wiring by depositing the conductive film 4 in the formed groove by focused ion beam induced deposition. Here the same energy 30
Although it is a monovalent Ga focused ion beam of keV, the beam current is adjusted to 0.5n by adjusting the aperture and lens voltage.
A, and the beam diameter was slightly reduced to 0.4 μm.
φ was used. That is, the current density was adjusted to about 1/6 that of the sputtering process. After that, a conductive film was deposited. In this example, the time required for this film deposition process is about 6
It was a minute. Mo (CO) ₆ gas was used as the reaction gas for forming the conductive film, and the wiring conductive film made of Mo was formed under the pressure of 20 mTorr on the substrate.

The reason why the current density of the ion beam is lowered midway is that focused ion beam induced deposition easily occurs at a low current density under the same beam scanning speed conditions. By adjusting the beam current density in this way, the throughput of the entire process is improved. Since using a beam with a low current density from the beginning reduces the processing speed of sputtering, the advantage of increasing the deposition rate by depositing in the groove is lost, and conversely, using a beam with a high current density for film deposition. As a result, the deposition rate becomes smaller and the deposition itself becomes less likely to occur. The current density of the ion beam during deposition of the conductive film is determined according to the gas pressure on the sample surface and the beam scanning conditions. Generally, the time required to adjust the beam current density is shorter than the process time, so that the throughput of the entire process does not decrease even if the current density is changed.
If the set value of the lens voltage in the focusing optical system at each current density and the aperture diameter to be selected are determined in advance, the time required for adjustment can be shortened.

FIG. 1 (c) shows a sectional structure of a wiring completed and deposited in the groove. Such cavities 5 often exist in the deposited film, which is caused by the fact that the film deposition rate on the side wall is higher than that on the bottom surface. In order not to generate this cavity, the gas pressure is increased. There are two methods of setting the gas adsorption time during which the beam is not irradiated for each scanning of one frame. When the gas pressure is increased, the amount of gas adsorbed near the bottom surface increases and the deposition rate increases. Further, by setting the adsorption time, the adsorption amount near the bottom surface also increases, and the difference in the deposition rate from the side surface decreases.

FIG. 2 shows a sectional view of a comparative example in which a focused ion beam induced deposition is directly performed to form a wiring without forming a groove by a usual method. The beam scanning conditions are the same as in the case of FIG. The process time in this case was about 15 minutes. Compared with the cross section of the wiring of FIG. 1 according to the present invention, although the process time is long, the cross sectional area is conversely small and the wiring resistance per unit length is large. When the resistance of the formed wiring having a length of 50 μm was measured, the wiring of FIG. 1 was 120Ω, whereas the resistance of FIG.
The wiring had a resistance of about 180Ω and 1.5 times. Estimating the process time required to form a wiring having the same resistance of 180Ω according to the present invention, the wiring film deposition time of 6 minutes is 2 /
Since it will be 4 minutes of 3, the groove formation time by sputtering is 0.1.
5 minutes, beam current density adjustment time 0.5 minutes, total 5 minutes. Therefore, the time for forming the wiring having the same resistance can be reduced to about ⅓ as compared with 15 minutes in the conventional method of FIG.

Example 2 In this example, an inspection wiring is newly formed by a focused ion beam induced deposition method without a risk of short circuit between existing wirings adjacent to each other on an integrated circuit having a multilayer wiring structure. An example is shown. First, for comparison, a conventional method will be described with reference to FIGS. 3 to 6, and then an embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a plan view showing the positional relationship of existing wirings on an integrated circuit forming inspection wirings, 6 and 9 are wirings exposed on the circuit surface, and 7 and 8 shown by broken lines are multilayer wiring structures. It is a lower layer wiring embedded in an interlayer insulating film (not shown) of the body. Here, it is assumed that 7 and 8 arranged apart from each other in the interlayer insulating film are connected for inspection. The existing inspection wiring to be newly laid is the existing wiring 6, 9
Do not connect to. Since the distance between the wirings 6 and 9 was only 2 μm, the width of the inspection wiring was 1 μm, and the distance between the inspection wiring and the existing wirings 6 and 9 was 0.5 μm. The thickness of the wirings 6 and 9 is about 1 μm.

FIG. 4 is a plan view showing a state in which the inspection wiring 13 is formed by the focused ion beam induced deposition method by a usual method in which the current density of the ion beam and the scanning speed are fixed. In the figure, 10 and 11 are contact holes which extend from the circuit surface to the lower layer wirings 7 and 8 and which are opened by focused ion beam sputtering. The surface area of the circuit in which the inspection wiring 13 is formed is flat.
When the inspection wiring 13 is formed in such a surface area, sputtered particles (the conductive film once deposited in the wiring formation area is spattered and scattered) adhere to the sidewalls of the existing wirings 6 and 9 during the formation of the wiring and are adjacent to each other. The width of the existing wiring becomes large. 1
Reference numeral 2 is a conductive film formed by redeposition.

FIG. 5 shows a cross-sectional structure taken along the line aa 'in FIG. 4. The original set value of the wiring interval was 0.5 μm as described above, but the actually formed inspection wiring was used. 1
3 and the conductive film 12 generated by reattachment is about 0.2 μm, and the margin for the positional accuracy of the process is reduced accordingly.

In the focused ion beam apparatus, fluctuations in the processing beam position occur and the beam diameter also tends to change, mainly due to the instability of the ion source unless the focusing optical system is ideally aligned. Therefore, an error is likely to occur in the wiring formation position. In this example, the inspection wiring 13 shown in FIG.
When a structure similar to the above was formed at 30 places in the circuit, 3
A short circuit between the existing wirings 6 and 9 and the inspection wiring 13 occurred due to a processing error that is considered to be caused by fluctuations in the beam position at some places.

FIG. 6 is a plan view of the short-circuited wiring, in which the inspection wiring 13 and the existing wiring 9 are short-circuited at point A. Even in such a case, the focused ion beam can be used to correct the point A by removing it by sputtering, but in the case of this example, since the wiring interval is narrow, it is possible to remove it. It is difficult to cope with the risk that the sputtered particles that are generated adhere to other places and cause a short circuit again.

Therefore, the wiring forming method of the present invention is required, and FIG. 7 shows a sectional structure when the inspection wiring is formed by the same method as the wiring forming method of the present invention shown in the first embodiment. . That is, the current density of the ion beam is switched to different current densities when forming the groove and when forming the conductive film in the groove. The depth of the groove formed in advance is 0.8 μm. During processing of the interlayer insulating film 17 at the time of forming the groove, the sputtered particles adhered to the existing wirings 6 and 9 adjacent to each other to form the adhered film 15. Since this is an insulating substance forming the insulating film 17. There is no problem of short circuit, and rather, it works as an insulating protective film in the subsequent wiring forming process. In the subsequent process of depositing the conductive film for wiring, the adhesion film 16 of the conductive material was slightly generated, but the distance between the inspection wiring 14 and the re-adhesion film 16 was 0.3 μm.
As described above, and further, since the insulating adhesion film 15 is formed on the base of the adhesion film 16 of the conductive material on the side of the existing wirings 6 and 9, the risk of short circuit is the same as that of the structure of the conventional example shown in FIG. It was significantly reduced in comparison. If there is no lower layer wiring directly under the wiring formation location, make the groove depth deeper than this example,
By forming the groove having an aspect ratio of 2 to 3, the amount of sputtered particles scattered outside the groove can be reduced, and the formation of the adhesion film 16 can be reduced to a negligible amount.

<Embodiment 3> In this embodiment, the supply of the reaction gas for forming the conductive film is not stopped, and the current density of the ion beam is not changed, but is fixed to a predetermined value. It shows an embodiment in which the groove and the wiring are formed by changing. Here, the beam stay time is defined as the time during which the beam is stopped per pixel during digital scanning. In the focused ion beam induced deposition, when the reaction gas pressure is constant, the deposition rate is determined by the beam current density or the beam residence time. FIG. 8 shows an example of the dependency of the deposition rate on the beam residence time. As is clear from this figure, positive and negative of the deposition rate, that is, deposition and sputtering can be switched by adjusting the beam residence time, and the scanning rate may be controlled to a predetermined rate by the beam scanning system. As described in the first embodiment, the same thing can be done with respect to the beam current density, but it is difficult to change the current density without changing the beam diameter, so that the aperture selection mechanism is used in combination. However, in this embodiment, the beam dwell time that can be changed more easily is changed,
This switching was performed. In addition to the beam current density and the beam dwell time, the pixel interval is also a parameter for beam scanning, but since it is limited to a value equal to or smaller than the beam diameter, the degree of freedom is smaller than these two. However, if the pixel interval is lengthened, the overlap of the beam tails is reduced, and the effective beam stay time is shortened, and if the pixel interval is shortened, the effective beam stay time is conversely lengthened.

As the beam, Ga monovalent ions having a beam diameter of 0.16 μm, a beam current of 1 nA and an energy of 25 keV were used. The beam current density is about 1.2 A / cm ² .
In the state where the same reaction gas for conductive film formation as in Example 1 was supplied from the nozzle to the sample surface, first, the beam residence time was 5 μm.
When the beam scanning was performed at s and a pixel interval of 0.2 μm, a groove was formed by sputtering. This process was continued for 15 minutes, resulting in a groove width of about 0.4 μm and a depth of about 0.6 μm. The cross-sectional shape of the circuit surface layer portion at this time is shown in FIG. The width of the groove 2 formed at this time is narrower than that in the case where sputtering is performed without blowing gas. This is because the sputtering rate on the side wall becomes smaller as the groove 2 is formed. This is because, on the side wall, the incident angle of the beam becomes large, the current density becomes small, the deposition rate becomes large relative to the sputtering rate, and the deposited film 18 (in this case, the Mo film) is formed.

As a result, when the groove is formed while supplying the gas, the width of the sputter groove becomes difficult to widen. As is clear from the figure, since the thin conductive film 18 is formed on the inner wall of the groove, it can be used as a wiring although it has a high resistance. When the existing wiring is exposed on this wall surface, contact is made and the conductive film 18 can be used as a part of the inspection wiring. However, since this conductive film is thin and has high resistance, it is sufficient for an inspection wiring to make the potentials equal, but when it is used as a normal wiring, it is further embedded. After the groove 2 is formed, the scanning condition of the focused ion beam is changed to a beam residence time of 1 μs (shortened to 1/5 of the time of forming the groove) and a pixel interval of 0.3 μm, and a conductive film (Mo film) is deposited. It was The cross-sectional shape after deposition is shown in FIG.

The wiring forming method in which the beam residence time is changed to form the groove and the conductive film is deposited in the groove is
This is performed by the apparatus of Example 4 described later, and the description of the apparatus will be described in detail in Example 4.

<Embodiment 4> FIG. 11 shows an embodiment of a wiring forming apparatus for carrying out the wiring forming method by the focused ion beam induced deposition method of the present invention. FIG. 3 is a block diagram of an apparatus for forming wiring by using the above. As shown in the figure, this apparatus controls the beam deflection and gas supply of the conventional focused ion beam apparatus so that the wiring forming process according to the present invention can be automatically performed. The focused ion beam device is a liquid metal ion source 2
0, focusing optical system 21, beam deflection system 22, gas supply system 2
3, a sample stage 25, and a secondary electron detector 26.
Reference numeral 24 is a sample, which is an integrated circuit for which wiring is to be formed.

The direction of control is indicated by an arrow. The coordinate data of the area where wiring is formed on the integrated circuit is the secondary electron detector 2
The secondary electron image is input to the control device 28 while observing the secondary electron image on the display device 27 connected to the display device 6. Process conditions necessary for sputtering processing and conductive film deposition are input to the control device 28 in advance so that optimum beam scanning conditions can be obtained based on the input coordinate data. In the actual wiring formation, the deflection system 22 is controlled, and the sputtering process is performed by slow beam scanning (long beam stay time).
The gas supply system 23 is operated to introduce the reaction gas, and the deflection system 2
2 is controlled to deposit the conductive film with fast beam scanning (short beam stay time). With such a device, groove formation,
Since the process conditions for film deposition are automatically switched, there is no human operation error and the work can be performed quickly, so that the yield and the throughput can be improved.

<Embodiment 5> This embodiment shows an example of an apparatus for forming a wiring by controlling the beam current density instead of controlling the beam residence time in the embodiment 4, and the wiring shown in the embodiment 1 is used. It is an example of an apparatus for carrying out the forming method. Hereinafter, a specific description will be given with reference to FIG. The description of the same parts as those of the apparatus of FIG. 11 is omitted. As shown in the figure, 29 is a lens voltage control unit, and 30 is an aperture selection mechanism. In this apparatus, 29 and 30 are adjusted to form a high current density beam, which is scanned at a slow speed by the control of the beam deflecting system 22 to perform sputter processing to form a necessary groove. After this is finished, the lens voltage is adjusted and the aperture is newly selected by controlling 29 and 30, the current density is lowered, and the reaction gas is introduced by the control of the gas supply system 23 while controlling the beam deflection system 22. Thus, the scanning speed is increased to deposit the conductive film. If such a device is used, the process conditions such as groove formation and film deposition are switched by automatically controlling the scanning speed of the beam deflection system 22, so that there is no human operation error and the process is quick. Work can be performed, and yield and throughput can be improved.

<Example 6> In this example, a wiring forming method using a focused ion beam induced etching step of supplying a gas dedicated to etching onto a sample at the time of groove formation and a focused ion beam induced deposition step is described. To do. Focused ion beam induced etching has the advantages that the processing speed is higher than that of sputtering, and that reaction products are removed as volatile substances, so that they do not easily adhere to the periphery of the processed portion. Hereinafter, a specific description will be given with reference to FIGS. 13 to 14.

In FIG. 13, a groove structure 32 is formed on the integrated circuit by focused ion beam induced etching, wiring is formed inside the groove, and existing adjacent wirings 31 formed in the surface insulating film are formed between adjacent wirings 31. 3 is a plan view of a main part of an integrated circuit in which new wiring 34 is formed and these are connected to each other. In the groove forming etching step, an etching gas containing XeF ₂ was supplied to the sample surface. This etching gas etches SiO ₂ , which is an insulating film, but does not easily attack aluminum, which is a wiring material, and can expose the existing lower layer wiring 31. 14 is the same as FIG.
FIG. 2B when the inspection wiring 34 is formed in the groove structure 32 of FIG.
It shows a sectional structure corresponding to -b '. Less than,
A new wiring 3 is provided between the existing wirings 31 embedded in the insulating film.
The procedure of the wiring forming step of connecting in 4 will be described.

The ion beam has a diameter of 1 μm and an energy of 2
A Ga1 cation ion beam of 0 keV was used. Groove structure 32
Has a width of 1.1 μm. After the etching of the surface insulating film 33 having a thickness of 0.8 μm under the supply of the etching gas containing XeF ₂ , a slight overetching to the interlayer insulating film 35 was performed, so that the depth of the groove became about 1 μm. . After this,
The etching gas was stopped, the gas supply to the chamber was switched to the W (CO) ₆ gas for forming the conductive film, and scanning was performed with the same beam to deposit the film 34 inside the groove. The surface insulating film 33 in the wiring formation region of the integrated circuit is removed, and the tungsten wiring 34 is embedded in a state where the existing wiring 31 and the interlayer insulating film 35 are exposed to connect the existing wirings.

<Embodiment 7> In this embodiment, a required wiring is directly formed in a predetermined area by a focused ion beam induced deposition method in an integrated circuit (ASIC) or the like for a specific application. A manufacturing example suitable for manufacturing an integrated circuit to which a new function is added in a short period of time without going through processes such as lithography, etching, etc. will be described. Hereinafter, a specific description will be given with reference to FIGS.

FIG. 15 is a plan view showing a part of the integrated circuit. In this integrated circuit, two types of modules 36 and 37 having different functions are formed in advance in the substrate, and the function can be changed depending on which one is connected to the other module 38. Usually, the wiring is changed in the final lithography and etching steps, but at least two masks are required for that purpose. If this wiring process is performed by the focused ion beam induced deposition method of the present invention, such redundancy can be omitted. However, since the conventional focused ion beam induced deposition method has a low deposition rate, the advantages of such a maskless process cannot be fully utilized. Reference numeral 39 in the drawing denotes a groove provided by a well-known lithography technique in order to shorten the wiring forming process. Focused ion beam induced deposition is performed using this groove to finally determine the module to be connected. FIG. 16 is a wiring diagram when the conductive film 40 is formed in this way and the module 38 and the module 37 are connected.

[0045]

As described above in detail, according to the present invention, the intended purpose can be achieved. That is, according to the wiring formation method by the focused ion beam induced deposition method of the present invention, the wiring formation is remarkably improved as compared with the conventional method, and the high speed and the high accuracy can be achieved. Further, according to the wiring forming apparatus of the present invention improved to realize the focused ion beam induced deposition method, it becomes possible to automatically perform the process control of the groove formation and the subsequent deposition of the conductive film. Since there is no mistake in operation and the work can be done quickly, the yield and throughput can be improved. As a result, it has become possible to significantly reduce the development period of high-density integrated circuits using inspection wiring formation by the focused ion beam induced deposition method.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing a wiring formation process flow according to an embodiment, which also serves as a principle explanation of a wiring formation method of the present invention.

FIG. 2 is a cross-sectional view of a wiring formed by a conventional method.

FIG. 3 is a plan view showing an existing wiring pattern on an integrated circuit which is a target for forming inspection wiring.

FIG. 4 is a plan view of a case where a new inspection wiring is formed by a conventional method between adjacent existing wirings of an integrated circuit.

5 is a cross-sectional view taken along the line aa 'in FIG.

FIG. 6 is a plan view showing a state in which a test wiring formed by a conventional method is short-circuited between adjacent existing wiring that should not be short-circuited.

FIG. 7 is a cross-sectional view of essential parts in the case where inspection wiring is formed on an integrated circuit by the wiring forming method of the present invention.

FIG. 8 is a characteristic diagram showing a relationship between a beam residence time and a film deposition rate for explaining an embodiment based on another principle of the wiring forming method.

FIG. 9 is a sectional view of the groove when the groove processing is performed without stopping the reaction gas supply.

FIG. 10 is a cross-sectional view of a buried wiring formed in the groove of FIG. 9 with a shorter beam residence time.

FIG. 11 is a block diagram showing an example of a wiring forming device of the present invention.

FIG. 12 is a block diagram showing another example of the wiring forming device of the present invention.

FIG. 13 is a plan view of an integrated circuit showing a relationship between a groove which is an inspection wiring formation region and an existing wiring pattern in the case where focused ion beam induced etching is also incorporated in the groove formation.

FIG. 14B is a view similar to FIG. 13B after formation of inspection wiring.
Sectional drawing corresponding to b '.

FIG. 15 is a schematic plan view of an integrated circuit in which a groove for forming a wiring is formed between modules which also have different functions.

FIG. 16 is a schematic plan view of an integrated circuit in which two modules similarly having different functions are connected by the wiring forming method according to the present invention.

[Explanation of symbols]

1 ... Insulating film, 2 ... Groove formed by focused ion beam sputtering, 3 ... Focused ion beam, 4 ...
Deposited conductive film, 5 ... Cavity, 6, 9 ... Exposed existing wiring, 7, 8 ... Existing lower layer wiring, 10, 11 ... Contact hole, 12 ... Conductive film formed by redeposition during wiring formation by a conventional method, 13 ... Inspection wiring formed by a conventional method,
14 ... Inspection wiring formed by the present invention, 15 ... Insulating redeposition film, 16 ... Conductive redeposition film, 17 ... Interlayer insulating film, 18 ... On inner wall of groove formed at low scanning speed while gas is supplied. Conductive film formed, 19 ... Conductive film buried by increasing scanning speed, 20 ... Liquid metal ion source, 21 ... Focusing optical system, 22 ... Beam deflection system, 23 ... Gas supply system, 2
4 ... Processed sample, 25 ... Sample stage, 26 ... Secondary electron detector, 27 ... Display device, 28 ... Control device,
29 ... Lens voltage control unit, 30 ... Aperture selection mechanism, 31 ... Existing lower layer wiring, 32 ... Groove formed by focused ion beam induced etching, 33 ... Surface insulating film,
34 ... Buried wiring formed by the present invention, 35 ...
Interlayer insulating film, 36, 37, 38 ... Module circuit, 39 ... Groove on insulating film, 40 ... Wiring formed by the present invention

Claims (11)

[Claims] 1. A step of forming a groove in a wiring formation region of a circuit board in accordance with a predetermined wiring shape, and a reaction gas for forming a predetermined conductor film in the groove formed in the step. And a step of depositing a wiring conductor film by a focused ion beam induced deposition method in which a focused ion beam is scanned in a groove in a state of being supplied under a scanning condition in which deposition is dominant. 2. The step of forming a groove in a wiring formation region of a circuit board in accordance with a predetermined wiring shape is a step of forming the groove under a beam scanning condition in which focused ion beam sputtering is dominant. The wiring forming method according to Item 1. 3. A step of forming a groove conforming to a predetermined wiring shape in a wiring formation area of a circuit board, and a focused ion beam is formed into a predetermined wiring with an etching gas being supplied to the wiring formation area. 2. The wiring forming method according to claim 1, which is a step of forming a groove by focused ion beam induced etching which scans according to a shape. 4. The wiring according to claim 1, wherein the step of forming a groove in a wiring formation region of the circuit board in accordance with a predetermined wiring shape is a step of forming the groove by using a lithography processing method. Forming method. 5. A step of forming a groove under a beam scanning condition in which focused ion beam sputtering is dominant and a step of depositing a wiring conductor film in which a focused ion beam is scanned under a scanning condition of deposition dominant scan in each step. It is assumed that the current density of the ion beam is controlled to a predetermined value, first the groove is formed under the scanning condition of high current density in which sputtering is dominant, and then the scanning condition of low current density in which deposition is dominant is switched to. The wiring forming method according to claim 2, wherein the conductive film is deposited in the groove by scanning the film. 6. A step of forming a groove under a beam scanning condition in which focused ion beam sputtering is dominant and a step of depositing a wiring conductor film in which a focused ion beam is scanned under a scanning condition of deposition dominant are scanned in respective steps. The ion beam residence time should be controlled to a predetermined time.First, scanning is performed under slow scanning conditions where sputtering predominates, then a groove is formed by lengthening the ion beam residence time, and then fast scanning conditions where deposition predominates. 3. The method for forming a wiring according to claim 2, wherein the conductive film is deposited in the groove by scanning in the groove and scanning in the groove by switching scanning conditions so that the residence time of the ion beam is shortened. 7. A step of forming a groove having an aspect ratio of 0.5 to 4.5 expressed in d / w, where w is an opening width of the groove and d is a depth of the groove forming step. The wiring forming method according to claim 1. 8. A method for forming a new wiring conductor layer when a desired existing wiring of a multilayer wiring structure having an interlayer insulating film is connected by a new wiring conductor layer as a method of forming the new wiring conductor layer. A circuit correction method for an integrated circuit formed by a wiring forming method. 9. A means for extracting an ion beam from a liquid metal ion source, having a desired current density with a focusing optical system, and converging the ion beam to a desired beam diameter, and deflecting the focused ion beam on a sample. Means for scanning the wiring forming area according to the wiring pattern to be formed, means for supplying a reactive gas onto the sample mounted on the stage, and secondary electrons generated by the ion beam scanning for detecting the scanning area of the scanning area. A means for displaying a secondary electron image, a control device for controlling at least an ion beam deflection system, a current density of an ion beam scanned according to a wiring pattern shape, a current density for forming a groove which is superior to sputtering, and a conductive layer which is superior to deposition. A current density control means for switching to a forming current density, and by controlling the current density to a desired value, groove formation and subsequent conductive layer in the groove are formed. Depositing a wiring forming apparatus using continuously performed so configured and made focused ion beam induced deposition in the same chamber to. 10. An ion beam is extracted from a liquid metal ion source, which has a desired current density in a focusing optical system.
A means for focusing to a desired beam diameter, a means for deflecting the focused ion beam and scanning the wiring forming region on the sample according to a wiring pattern to be formed, and a reaction gas on the sample mounted on the stage For supplying secondary electrons, means for detecting secondary electrons generated by ion beam scanning and displaying secondary electron images in the scanning region, a controller for controlling at least the ion beam deflection system, and scanning in accordance with the wiring pattern shape. Means for controlling the dwell time of the beam by switching the scanning speed of the ion beam. By controlling the dwell time of the beam to a desired value, groove formation and subsequent deposition of a conductive layer in the groove are performed. A wiring forming apparatus using focused ion beam induced deposition configured so that it can be continuously performed in the same chamber. 11. A control device controls an ion beam deflection system and an aperture selection mechanism arranged between the focusing optical system and the beam deflection system to enable selection of an aperture of a desired shape. The wiring using focused ion beam induced deposition according to claim 9 or 10, wherein the reaction gas supply means is controlled to stop the gas supply by opening and closing the supply valve, or to switch the gas species. Forming equipment.