JPH04157720A - Sputtering method - Google Patents

Abstract

PURPOSE:To obtain a sputtering method which can control the thickness of a sputtered film automatically and with high accuracy by a method wherein a growth operation is stopped at the point of time when the resistance value of a conductive thin film formed by a sputtering operation has reached the resistance value at a prescribed film thickness of a conductive film which is sputtered and grown on a dummy substrate or on an insulating film. CONSTITUTION:A prescribed DC voltage is applied across a lid plate 6, substrate holders 7A to 7D which are conductive to the lid plate 6 and substrates 15, to be treated, which are loaded on them. A shutter 8 is opened; an Al target 10 on a target electrode (cathode 3) is sputtered; Al thin films are grown on the substrates 15 to be treated. At this time, the target is sputtered while the resistance value of an Al thin film grown on an insulating substrate 9 for measuring use is being measured simultaneously on the substrates 15 to be treated. The point of time when the resistance value has reached the resistance value of an Al thin film having a prescribed film thickness is detected by using a comparison circuit or the like. The shutter 8 is closed automatically by using a driving gear; a sputtering power supply is cut off; the sputtering operation is stopped. Thereby, the thickness of the Al thin films grown on the substrates 15 to be treated can be formed in a desired thickness with good accuracy.

Description

[Detailed Description of the Invention] [Summary] A sputtering method, in particular a sputtering method for a conductive thin film, that allows sputtering film thickness to be controlled automatically and with high precision without requiring time or manpower. When forming a conductive thin film having a predetermined thickness on a substrate to be processed by a sputtering method, the process may be performed on a dummy substrate having an insulating material surface placed near the substrate to be processed or Sputtering is performed while measuring the resistance value of the conductive thin film sputter-grown on the insulating film of the substrate, and when the resistance value of the conductive thin film reaches the resistance value at a predetermined thickness of the conductive thin film, the growth is completed. When continuously growing conductive thin films having a predetermined thickness on multiple substrates to be processed using a configuration that stops the process or a single-wafer sputtering device,
A dummy substrate having an insulating surface is sent to the vicinity of the substrate to be processed one by one, and the resistance value of the conductive thin film grown on the dummy substrate at the same time as the substrate to be processed is measured. Sputtering is performed while the conductive thin film is sputtered, and the growth is stopped when the resistance value of the conductive thin film reaches a resistance value at a predetermined thickness of the conductive thin film, or in the above method, further, the resistance of the conductive thin film is sputtered. It has a configuration in which the time required for the resistance value of the conductive thin film to reach a predetermined thickness is measured, and the sputtering current and sputtering voltage are controlled so that sputtering to the next substrate to be processed is completed within a predetermined time.

[Industrial application field]

The present invention relates to a sputtering method, and in particular to a method for sputtering conductive thin films.

When growing a conductive thin film, such as a metal thin film, using a sputtering device, the sputtering speed changes and the sputtered film thickness changes as the usage time of the target passes.

On the other hand, as semiconductor devices become more highly integrated, the width of metal interconnections using sputter-formed aluminum thin films or the like has also been significantly reduced.

Under these circumstances, 1. In order to improve the quality of wiring and ensure the reliability of semiconductor devices, a sputtering method that can maintain a constant sputtered film thickness for each semiconductor substrate is desired.

[Conventional technology]

Conventionally, the following method has been used to obtain a nearly constant sputtered film thickness with no variation from substrate to substrate using a sputtering device whose sputtering speed changes as the target is used. Two methods were mainly used.

The first method is to use up the target once in a given sputtering device, record data on the relationship between the usage time of the target and the sputtered film thickness within a certain period of time, and then use this data to maintain a certain sputtered film thickness. This is a method in which a correction curve of sputtering current and sputtering voltage with respect to the usage time of the target is obtained to obtain the thickness, and the current and voltage are corrected every time the target is used.

The second method is a method in which each time sputtering on one substrate is completed, the film thickness is measured and the sputtering current and sputtering voltage for the next substrate are corrected.

[Problem to be solved by the invention]

However, in the first method, the sputtering current and sputtering voltage are indirectly corrected based on a correction curve created with another target, so the reliability of the film thickness accuracy is low (and the second method The problem was that it required a significant increase in time and manpower.

Therefore, an object of the present invention is to provide a sputtering method that can automatically and highly accurately control the sputtered film thickness without requiring much time or manpower.

[Means to solve the problem]

The above problem arises when forming a conductive thin film having a predetermined thickness on a substrate to be processed by sputtering, and when forming an insulating film on a dummy substrate having an insulating material surface placed near the substrate to be processed or an insulating film on the substrate to be processed. Sputtering is performed while measuring the resistance value of a conductive thin film sputter-grown on the conductive thin film, and the growth is stopped when the resistance value of the conductive thin film reaches the resistance value at a predetermined thickness of the conductive thin film. When a conductive thin film having a predetermined thickness is continuously grown on a plurality of substrates to be processed using the sputtering method according to the invention or a single-wafer sputtering device, a dummy having an insulating material surface is placed near the substrates to be processed. The substrates are sequentially sent out one by one to be processed, and sputtering is performed while measuring the resistance value of the conductive thin film grown on the dummy substrate at the same time as the substrate to be processed, so that the resistance value of the conductive thin film is A sputtering method according to the present invention in which the growth is stopped when the resistance value of the conductive thin film reaches a predetermined thickness, or in the above method, further, the resistance value of the conductive thin film is This problem is solved by the sputtering method according to the present invention, which measures the time required to reach the resistance value when thick and controls the sputtering current and sputtering voltage so that sputtering to the next substrate to be processed is completed within a predetermined time.

[For production]

That is, in the method of the present invention, sputtering is continued while the resistance value of the growing conductive sputtered film is directly measured on a dummy substrate placed on or near the substrate to be processed, and the resistance value is determined when the resistance value reaches a predetermined film thickness. When the resistance value of
Spatter is stopped by closing the shutter, etc.
The sputtered film thickness can be controlled with high precision.

In particular, in the single-wafer sputtering method, a new dummy substrate surface having an insulator surface is sequentially delivered to a position near the substrate to be processed for each substrate to be processed, and the resistance value of the sputtered film grown on that surface is constantly measured. By detecting a predetermined sputtered film thickness and automatically stopping sputtering, it is possible to control the sputtered film thickness with high precision without using time or manpower.

Furthermore, by detecting changes in the time required to obtain a predetermined film thickness, the sputtering current and sputtering voltage are controlled during sputtering to subsequent substrates, and the sputtering time required to obtain a predetermined film thickness is made uniform. Advantageous automation of manufacturing processes.

〔Example〕

The present invention will be specifically explained below with reference to illustrated embodiments.

1II is a schematic diagram of a batch type sputtering apparatus according to the first embodiment of the present invention, in which (a) is a side sectional view of the apparatus, (b) is a plan view of a substrate holder, and (C) is an insulator for resistance measurement. FIG. 2 is a schematic diagram of a single-wafer sputtering apparatus according to a second embodiment of the present invention, in which (a) is a plan view of the main part of the apparatus, and (b) is a plan view of the base.
) A sectional view taken along the line A-A of the main part of the device, and FIG. 3 is a schematic diagram of the arrangement of the insulating tape for resistance measurement according to the second embodiment, (a)
is out-of-plane - 1 (b) is a sectional view taken along the line M-M, and Fig. 4 is a 2nd
A schematic diagram of an insulating tape for resistance measurement according to an example of (a
) is a plan view, and (b) is a sectional view taken along the line X-X.

Identical objects are designated by the same reference numerals throughout the design.

When applying the present invention to batch-type sputtering, for example, as shown in FIG. 1(a), a fixed target electrode 3 placed on a base l via a sliding roller 2 is A bottom plate 4 that rotates (revolutions) around the pillar, and a dome-shaped lid 6 placed on the bottom plate 4 via a vacuum packing 5.
Substrate holders 7A to 7D, etc., which rotate about their respective spindles are disposed on the lid portion 6, and a shutter 8 that rotates on the bottom plate 4 and covers the target electrode 3 is provided.
In a batch type sputtering apparatus similar to the conventional one, a rectangular ceramic plate 17 is placed in the empty space of the sputtering area, for example, in the center of the ceiling of the dome-shaped lid part 6, as shown in FIG. 1(C). A dummy base for resistance measurement, ie, an insulating base for resistance measurement 9, which has electrode terminals 18A and 18B made of a metal vapor deposited film such as AI formed on both ends thereof, is arranged. In the figure, 10 is, for example, aluminum (A1
) Target, 11 is an airtight/insulating gasket, 12 is a rotating bearing, and 15 is a substrate to be processed.

Further, the substrate holders 7A to 7D, etc. are, for example, shown in FIG.
As shown in b), the metal disk 13 has a plurality of substrate mounting grooves 14, and substrate fixing claws 16 for fixing the mounted substrate 15 to be processed are arranged around the substrate mounting grooves 14. It has the same structure as the conventional one.

During sputtering, the substrate holders 7A to 7A on which the substrate to be processed 15, which is disposed in the lid part 6 and which is mounted on the substrate 15 to be processed, are revolved around the target electrode 3 via the bottom plate 1 by a drive device (not shown). After maintaining the inside of the sputtering apparatus, in which the sputtering apparatus 7D and the like are rotated by a drive device (not shown), in an argon (Ar) atmosphere at a predetermined pressure of, for example, about 10-'' Torr, a That is, a predetermined DC voltage is applied between the cover plate 6, the substrate holders 7A to 7D, etc. which are electrically connected to the cover plate 6, and the target substrate 15 mounted directly thereon, and the shutter 8 is opened to expose the target. Electrode (cathode) 3
The upper Af target 10 is sputtered to grow an Al thin film on the substrate 15 to be processed. At this time, in the method of the present invention using the above-described apparatus, sputtering is performed while measuring the resistance value of the Al thin film grown on the insulating substrate 9 for resistance measurement at the same time as on the substrate 15 to be processed, and the resistance value is determined to be a predetermined value. A comparator circuit or the like detects the point in time when the resistance value of the Al thin film is reached, and a drive device (not shown) automatically closes the shutter 8 and cuts off the sputtering power supply to stop sputtering.

In this way, on the substrate 15 to be processed, the thickness of A[
As the thin film grows, the thickness of the thin film grown on the insulating substrate 9 for resistance measurement is measured over time from its resistance value, and the resistance value matches the resistance value of the desired thickness measured in advance. By stopping sputtering at this point, the substrate to be processed 15
The thickness of the Al thin film grown thereon can be precisely formed to a desired thickness.

In addition, in the method of the present invention used for single-wafer sputtering, a plurality of substrates are formed radially on a disc-shaped substrate holder 19 serving as a turntable, as shown in FIG. 2(a), for example. By rotating the substrate holder 19, the substrate 15 to be processed is mounted in the mounting groove 14 and fixed by the substrate fixing claws 16 with the facets facing the rotating shaft 19S side of the substrate holder 19, for example, to the target electrode 3. For example, the AI2 target 10 is moved sequentially to a position directly facing the target 10 (a turntable type single-wafer sputtering apparatus similar to the conventional one is used). A hole for sputtered film thickness detection formed in a corresponding empty space is shown.

FIG. 2(b) is a cross-sectional view taken along the line A-A in FIG. 2(a), and as shown in this figure, in the single-wafer type sputtering apparatus, as usual, The substrate 15 to be processed and the above Al
For example, a rotating shutter 8 is provided between the target IO and the target IO. Furthermore, at the rear of the sputtered film thickness detection aperture 20 formed in the substrate mounting groove 14 at the above position, a sputtered film for film thickness detection is simultaneously deposited on the substrate 15 to be processed through this aperture 20. An insulating tape 21 for resistance measurement, which is a dummy base for resistance measurement, is arranged.

FIG. 3 is a plan view (a) and a sectional view taken along the line M-M, schematically showing the arrangement of the insulating tape 2I for measuring the resistance of the sputtered film.

Moreover, FIG. 4 is a plan view (a) schematically showing an example of the above-mentioned insulating tape 21 for resistance measurement, and a cross-sectional view taken along the line X--X.

The insulating tape 21 for resistance measurement shown in FIG. 4 is formed of a heat-resistant sheet of polyimide or the like with a thickness of about 0.5 mm, and is formed by a vapor deposition method or the like from the edges on both sides of the front and back surfaces. Al with a thickness of about 2 to 3 μm
A pair of electrode terminals (22A+, 22At) consisting of a membrane, etc.
(22Bl, 2282), etc. are formed at a predetermined distance d, and both ends are wound into a roll.

Note that the distance d between the electrodes is determined by the distance d between the film thickness detection openings 2 to avoid short-circuiting between adjacent electrodes after sputtering.
It is sufficiently wider than the width W of 0 (needs to be formed in advance).

This insulating tape 21 for resistance measurement is as shown in FIG.
When the substrate holder 19 having a turntable function is sent to the front of the target and stopped, the substrate holder 1
9 as close as possible to the back surface of the substrate holder 19 at the rear of the sputtered film thickness detection opening 20 formed in the substrate mounting groove 14 of No.
2A1 and 22A2 (FIG. 4) are both arranged at fixed positions exposed within the sputtered film thickness detection opening 20. This insulating tape 21 for resistance measurement is connected to the electrode terminals of the next row, for example, 22B1.22Bt (4th ) is moved so that it is exposed in the sputtered film thickness detection aperture 20.

When sputtering occurs, the shutter 8 (FIG. 2b) is opened, and the resistance measuring terminals z3A and 23B move from both sides of the tape 21 so as to sandwich the tape 21, and the electrode terminals on the side surface of the tape 21, for example, 22A1.22A!
The resistance of the sputtered film grown on the tape 21 while holding the tape (Fig. 4) is constantly measured (it may be measured on the back side of the tape), and when the resistance value reaches the resistance value of the predetermined film thickness, ,
The shutter 8 (FIG. 2b) is closed to stop the growth of the sputtered film, and then the substrate holder 19 (FIG. 2a) is turned so that the next substrate 15 to be processed is moved to the target 10 (second
A sputtered film is grown on the next substrate to be processed by the same operation as described above.

According to the method of the present invention as shown in the examples above, it is possible to form a uniform film thickness with high film thickness accuracy on a plurality of substrates using a single-wafer type sputtering apparatus without requiring any extra manpower. AI! It is possible to form a conductive sputtered film such as the following.

In addition, during the sputter growth described above, the time required for the conductive sputtered film to reach a predetermined thickness is automatically measured and its fluctuations are detected, and the sputtering current and sputtering voltage for the next substrate to be processed are determined based on pre-experimented data. If adjustment is made so that the growth of a sputtered film of a predetermined thickness on each substrate to be processed is completed in a substantially constant time, it will be more advantageous for automation of the manufacturing process that is sent by the tact method.

In the above examples, the resistance value of the sputtered film was measured using a resistance measurement substrate (substrate or tape) placed near the substrate to be processed.
Without using the above-mentioned resistance measurement substrate, it is also possible to measure by performing sputtering with the resistance measurement electrode in direct contact with a predetermined location on the substrate to be processed that does not affect performance. .

〔Effect of the invention〕

As explained above, according to the present invention, in a sputtering method using a batch type and single wafer type sputtering apparatus,
It is now possible to control the sputtered film thickness automatically and with high precision without requiring time or manpower, and it is also possible to uniformize the sputtering time to obtain a desired film thickness, especially in single-wafer sputtering methods. Become.

Therefore, the present invention is effective in improving the manufacturing yield and reliability of semiconductor devices and automating the manufacturing process.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a batch sputtering apparatus according to a first embodiment of the present invention, in which (a) is a side sectional view of the apparatus, (bl is a plan view of a substrate holder, and (C) is an insulator for resistance measurement. FIG. 2 is a schematic diagram of a single-wafer sputtering apparatus according to a second embodiment of the present invention, in which (a) is a plan view of the main part of the apparatus, and (b) is a schematic diagram of the main part of the apparatus. 3 is a schematic diagram of the arrangement of the insulating tape for resistance measurement in the second embodiment, (al is a plan view (a), (b) is a sectional view taken along M-M, FIG. 4 is a schematic diagram of an insulating tape for resistance measurement in the second embodiment, where (a) is a plan view and (b) is a cross-sectional view taken along the line X-x. In the figure, l is a base; 2 3 is a sliding roller, 3 is a target electrode 4 is a bottom plate, 5 is a vacuum packing, 6 is a lid, 78 to 7D are substrate holders, 8 is a shutter, 9 is an insulating base for resistance measurement, 1O is an AI! target, 11 12 is an airtight/insulating gasket, 12 is a rotating bearing, 13 is a metal disk, 14 is a substrate mounting groove, 15 is a substrate to be processed, 16 is a substrate fixing claw, 17 is a ceramic plate, and 18A and 518B are electrode terminals. (α) 1 crocodile j1!/) Iken] 4 1 page [ko (b)
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kII Reisei O, JP Menguchi

Claims (3)

[Claims] 1. When forming a conductive thin film having a predetermined thickness on a substrate to be processed by sputtering, sputter growth is performed on a dummy substrate having an insulating material surface placed near the substrate to be processed or on an insulating film of the substrate to be processed. Sputtering is performed while measuring the resistance value of the conductive thin film, and the growth is stopped when the resistance value of the conductive thin film reaches the resistance value at a predetermined thickness of the conductive thin film. sputtering method. 2. When continuously growing conductive thin films having a predetermined thickness on a plurality of substrates to be processed using a single-wafer sputtering device, a dummy substrate having an insulating surface is placed near the substrates to be processed. Sputtering is performed while measuring the resistance value of the conductive thin film grown on the substrate to be processed and simultaneously on the dummy substrate. A sputtering method characterized by stopping growth when the resistance value at the time of thickness is reached. 3. 3. The method according to claim 2, further comprising: measuring a time for the resistance value of the conductive thin film to reach a resistance value at a predetermined film thickness of the conductive thin film, and completing sputtering to the next substrate to be processed within the predetermined time. A sputtering method characterized by controlling sputtering current and sputtering voltage so as to