Ruthenium-cobalt alloy target sputtering method for forming component gradient film

Abstract

The invention provides a ruthenium-cobalt alloy target sputtering method for forming a component gradient film. The ruthenium-cobalt alloy target sputtering method comprises the following steps that two long-strip-shaped targets with different ruthenium-cobalt component proportions are sequentially and alternately spliced to form a ruthenium-cobalt alloy plane sputtering target; a movable magnet set is arranged in the width direction of the ruthenium-cobalt alloy plane sputtering target material, and the movable magnet set is at least allowed to move in the width direction; and controlling a moving parameter of the moving magnet group along the width direction, so that the position with the maximum etching rate moves along the width direction. According to the method, two ruthenium-cobalt alloy targets with different component proportions are alternately spliced and are matched with a magnet group capable of periodically moving, so that the etching rate of the ruthenium-cobalt alloy targets in the sputtering process is adjusted; continuous gradual change control over the ruthenium-cobalt component proportion in the thickness direction during film forming is achieved in the mode of dynamically adjusting the magnetic field position, and the proportion of ruthenium and cobalt in the film can be flexibly controlled.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a sputtering method of a ruthenium-cobalt alloy target for forming a composition-gradient thin film. Background Art

[0002] In the existing magnetron sputtering coating technology, a method similar to forming a sandwich film is used to achieve gradient thin films. Specifically, target materials with different compositions are set in different sputtering chambers. After the substrate is sputtered to form a film layer with one component, the substrate is transferred to another sputtering chamber with a different target material composition and continued to sputter, thereby forming a gradient thin film.

[0003] The formation of gradient thin films requires constant replacement of target materials with varying composition ratios. This not only results in low production efficiency but also makes the process complex and tedious. Furthermore, the resulting gradient films exhibit distinct stratification, with distinct dielectric interfaces, resulting in high stress and high production costs. Summary of the Invention

[0004] The object of the present invention is to provide a ruthenium-cobalt alloy target sputtering method for forming a composition-gradient film, thereby forming a composition-gradient film without an obvious dielectric interface.

[0005] According to one object of the present invention, the present invention provides a method for sputtering a ruthenium-cobalt alloy target to form a compositionally graded thin film, comprising the following steps:

[0006] S1. Two long strip targets with different ruthenium and cobalt composition ratios are alternately spliced in sequence to form a ruthenium-cobalt alloy planar sputtering target;

[0007] S2. Arranging a movable magnet group along the width direction of the ruthenium-cobalt alloy planar sputtering target, and allowing the movable magnet group to move at least along the width direction;

[0008] S3. Control the movement parameters of the movable magnet group along the width direction to move the maximum etching rate position along the width direction.

[0009] Furthermore, in step S3, by regulating the movement amplitude of the movable magnet group along the width direction, the movement distance of the maximum etching rate position along the width direction and the time ratio of different stop positions are synchronously controlled to control the component ratio of the gradual or gradient morphology film formed by sputtering.

[0010] Furthermore, in step S3, by regulating the dwell time of the movable magnet group when it moves to different positions along the width direction, the dwell time of the maximum etching rate position when it moves to different positions along the width direction is synchronously controlled.

[0011] Furthermore, in step S2, the movable magnet group includes several groups of magnets, and the several groups of magnets are respectively allowed to move in a direction perpendicular to the target surface, and the magnets are arranged with N poles and S poles alternately facing upwards along the width direction.

[0012] Furthermore, in step S3, the distance between each group of the magnets and the target surface is controlled respectively so that the position of the maximum etching rate moves along the width direction.

[0013] Furthermore, in the two long strip targets having different ratios of ruthenium to cobalt, the content of ruthenium or cobalt is greater than or equal to 20%.

[0014] Furthermore, the widths of the two long strip targets having different ruthenium and cobalt composition ratios are equal.

[0015] Furthermore, the movement amplitude of the movable magnet group along the width direction is equal to the sum of the widths of two adjacent long strip targets.

[0016] Furthermore, in S1, two long strip targets are alternately spliced and fixed on the upper surface of the target backing plate, and the movable magnet group is arranged below the target backing plate.

[0017] Furthermore, the movement of the movable magnet group along the width direction is reciprocating movement.

[0018] The technical solution of the present invention avoids the tedious operation of frequently replacing targets in traditional technology by alternately splicing two ruthenium-cobalt alloy targets with different composition ratios and cooperating with a periodically movable magnet group, thereby significantly improving production efficiency. It also realizes continuous gradual control of the ruthenium-cobalt composition ratio along the thickness direction during film formation by dynamically adjusting the magnetic field position, which can flexibly control the ratio of ruthenium and cobalt in the film and prepare a composition-gradient film with a more uniform composition transition. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a schematic diagram of the welding structure of the ruthenium-cobalt target brazing material and the target backing plate according to the embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the welding structure of the actual ruthenium-cobalt target brazing material and the target backing plate according to an embodiment of the present invention;

[0022] Figure 3Schematic diagram of the structure of the target, target backing plate and magnet assembly according to an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of controlling the magnet group according to an embodiment of the present invention;

[0024] In the figure: 1. Target back plate; 2. Splicing gap; 3. Welding layer; 4. N-pole upward magnet; 5. S-pole upward magnet; 6. Component A target; 7. Component B target. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore should not be understood as limiting the present invention.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a communication between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0028] Example 1

[0029] like Figures 1-4 As shown, the technical solution of the present invention provides a ruthenium-cobalt alloy target sputtering method for forming a composition-graded thin film, comprising the following steps:

[0030] Step 1: Fix two ruthenium-cobalt alloy targets with different composition ratios on the target backing plate, and splice the two ruthenium-cobalt alloy targets alternately along the width direction of the target.

[0031] The two ruthenium-cobalt alloy targets are long strip targets, and the widths of the two ruthenium-cobalt alloy targets are equal or different, preferably the widths of the two ruthenium-cobalt alloy targets are equal; the width setting of the two ruthenium-cobalt alloy targets can affect the component ratio of the gradual or gradient morphology film formed by subsequent sputtering;

[0032] The gap between the two ruthenium-cobalt alloy targets is less than 1 mm; the sum of the ruthenium and cobalt contents of the two ruthenium-cobalt alloy targets is equal to 100%, and the ruthenium or cobalt content is greater than or equal to 20%; for example, when the ruthenium content is 25%, the cobalt content is 75%;

[0033] A magnet group with N poles and S poles facing upward alternately and arranged in sequence along the width direction of the target is set under the target back plate;

[0034] Step 2: During the sputtering process, the magnet group moves periodically along the width direction of the target material; the sputtering area of the ruthenium-cobalt alloy target material is adjusted by the periodic reciprocating motion of the magnet group; the sum of the widths of the two ruthenium-cobalt alloy targets is less than or equal to the width of one reciprocating motion cycle of the magnet group, and the width of one reciprocating motion cycle of the magnet group is equal to the distance between the center of the north pole magnet and the center of the south pole magnet;

[0035] Step 3: Control the periodic movement time, frequency and period of the magnet group. The movement frequency of the magnet group is one or more periods of periodic movement after each sputtering is completed, thereby forming a gradient film composition. In the prepared composition gradient film, the ratio of ruthenium to cobalt content of the two ruthenium-cobalt alloy targets gradually changes with the sputtering time during the formation of the film, thereby achieving a composition gradient.

[0036] Example 2

[0037] Based on Example 1, this embodiment further describes the sputtering method of Example 1 in detail as follows:

[0038] Regarding target material preparation: This embodiment uses 99.99% pure ruthenium and pure cobalt powders, which are ball-milled in atomic ratios of 70:30 and 30:70, respectively. The mixed alloy powders of the two components are then compression-molded to obtain two ruthenium-cobalt alloy billets of regular shape. The billets are sintered using hot isostatic pressing technology into high-density, high-purity ruthenium-cobalt targets with different composition contents, ensuring that the composition ratios of ruthenium and cobalt are 70% ruthenium:30% cobalt and 30% ruthenium:70% cobalt, respectively.

[0039] Finally, several groups of ruthenium-cobalt targets with different composition contents are brazed and bound to the same target backing plate 1 (eg Figure 1As shown), there is a splicing gap 2 after binding, and the splicing gap 2 is controlled within 1mm (as shown Figure 2 As shown), a welding layer 3 is formed between the ruthenium-cobalt target and the target backing plate 1.

[0040] Sputtering process:

[0041] The prepared ruthenium-cobalt target is installed in a sputtering device. In the sputtering device, one or more magnet groups are placed under the target back plate 1; each magnet group includes a magnet 4 with an N pole facing upward and a magnet 5 with an S pole facing upward, and the two magnets are arranged at intervals;

[0042] During the sputtering process, the magnet group is periodically moved along the width direction of the target material to adjust the position of the magnetic field and control the influence of the magnetic field on the target material etching rate during the sputtering process; by controlling the movement frequency and period of the magnet group, the gradient change of the ruthenium-cobalt film is achieved.

[0043] The sputtering process of this embodiment effectively controls the composition ratio of the formed film. For example, by gradually changing the ruthenium-cobalt ratio from 40% ruthenium:60% cobalt to 60% ruthenium:40% cobalt, a gradient film with excellent adhesion and stability is formed. Compared with traditional methods, this sputtering method effectively controls the composition gradient of the film, improving film uniformity and adhesion, reducing internal stress in the film, and lowering material costs. Furthermore, the gradient can be precisely adjusted by adjusting the movement period of the magnet group.

[0044] Example 3

[0045] Based on Example 1 and Example 2, this embodiment further describes the specific steps of the sputtering method in detail:

[0046] like Figure 3 As shown, during the actual sputtering process, a plurality of magnet groups are arranged below the target back plate. The magnet group includes multiple groups of magnets arranged in an arranged manner. The magnets are arranged along the width direction of the target, and the polarities of the magnets are arranged alternately in sequence.

[0047] Specifically, if Figure 3 As shown, the black rectangular block and the gray rectangular block respectively represent the N-pole upward magnet 4 and the N-pole upward magnet 4 after the position is moved, and the white rectangular block and the dotted rectangular block respectively represent the S-pole upward magnet 5 and the S-pole upward magnet 5 after the position is moved;

[0048] The magnetic flux lines emitted by the N-pole-upward magnet 4 pass through the target and then fall back to the S-pole-upward magnet 5, forming a series of parabolic magnetic flux lines. The position where the magnetic flux lines extend parallel to the target surface has the highest sputtering efficiency. The target at this position has the highest sputtering efficiency, which is also the reason for the formation of target etching racetracks. In other words, the target material utilization efficiency corresponding to this position is the highest. After the target material has been used for a period of time, the target surface will become periodically uneven.

[0049] In this embodiment, the magnet group is periodically moved along the width direction of the target material to adjust the position of the magnetic field, and the effect of the magnetic field on the etching rate of the target material is utilized. Figure 3 and Figure 4 As shown, in this embodiment, the two ruthenium-cobalt alloy targets are marked as component A target 6 and component B target 7, respectively. Under normal circumstances, the etching rate at position ① is the highest, and a concave etching track will be formed. At this time, the etching rate of component A target is the highest, and the etching rate of component B target 7 is relatively low, so that the composition of the thin film formed by sputtering is more similar to component A target 6; when the magnet group moves to the moved position, such as the position of the magnet represented by the gray rectangular block and the dotted rectangular block, the etching rate at position ② is the highest, and a concave etching track will be formed. At this time, the etching rate of component B target 7 is the highest, so that the composition of the thin film formed by sputtering is more similar to component B target 7.

[0050] Thus, by periodically adjusting the position of the magnet group, the composition ratio of the formed film can be controlled, for example, the content of ruthenium and cobalt can be gradually changed from 40%:60 to 60:40%.

[0051] like Figure 4 As shown, in this embodiment, in order to increase the target utilization rate of the existing coating equipment when sputtering pure metal targets, that is, to reduce the etching tracks formed on the target, the magnet group in the equipment is set to move back and forth periodically along the width direction of the target, and the time, frequency, period, etc. of the periodic movement of the magnet group are controlled to match the purpose of the present invention.

[0052] In this embodiment, the component ratio of the gradual or gradient morphology film formed by sputtering is controlled by regulating the movement amplitude of the magnet group and the time ratio of the magnet group staying at position ① and position ②.

[0053] Specifically, the composition ratio of the gradient film is controlled by adjusting the dwell time of the magnet group at the positions of the A-component target 6 and the B-component target 7. The movement range of the magnet group can be controlled by moving the magnet from the center of the A-component target 6 to the center of the B-component target 7, and then gradually moving from the center of the A-component target 6 to the middle position between the A-component target 6 and the B-component target 7. The dwell time of the magnet group can be controlled by controlling the length of time the magnet stays at the center of the B-component target 7.

[0054] During the movement of the magnet group, the movement speed of the magnet group can be uniform or non-uniform.

[0055] Furthermore, it's understandable that the composition ratio of the film can be controlled by adjusting the distance between the magnet assembly and the target. Theoretically, the smaller the distance between the upper surface of the magnet assembly and the target surface, the greater the magnetic field strength and the higher the sputtering efficiency. For example, when the magnets are positioned at component A target 6, the distance can be reduced to achieve a higher sputtering rate, while when the magnets are positioned at component B target 7, the distance can be increased to achieve a lower sputtering rate.

[0056] At the same time, during the preparation process, by changing the widths of the two ruthenium-cobalt alloy targets, namely the widths of the long strips of component A target 6 and component B target 7, the component ratio of the gradual or gradient morphology film formed by subsequent sputtering can also be affected.

[0057] Since the magnet group in the existing device moves back and forth periodically, the moving range of the magnet group of the device is limited. Figure 4 As shown, in this embodiment, the sum of the widths of the long strips of target material A component 6 and target material B component 7 should be less than or equal to the width of one reciprocating motion cycle of the magnet group, that is, the distance between the center of the N-pole magnet and the center of the S-pole magnet.

[0058] The width of the long strip target of component A target 6 and the width of the long strip target of component B target 7 can be equal or different, but in order to maximize the degree of composition gradient of the formed composition gradient film, equal width is the best choice.

[0059] The present invention alternately splices two ruthenium-cobalt alloy targets with different composition ratios and cooperates with a periodically movable magnet group to adjust the etching rate of the ruthenium-cobalt alloy target during sputtering; by dynamically adjusting the magnetic field position, continuous gradual control of the ruthenium-cobalt composition ratio along the thickness direction during film formation is achieved, which can flexibly control the ratio of ruthenium and cobalt in the film, and can produce a film with more uniform composition transition and higher gradient accuracy, thereby realizing the preparation of composition gradient films.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for sputtering a ruthenium-cobalt alloy target to form a compositionally graded thin film, characterized in that: The following steps are involved: S1. Two long strip targets with different ruthenium and cobalt composition ratios are alternately spliced in sequence to form a ruthenium-cobalt alloy planar sputtering target; S2. Arranging a movable magnet group along the width direction of the ruthenium-cobalt alloy planar sputtering target, and allowing the movable magnet group to move at least along the width direction; S3. Control the movement parameters of the movable magnet group along the width direction to move the maximum etching rate position along the width direction.

2. The ruthenium-cobalt alloy target sputtering method according to claim 1, characterized in that: In step S3, the component ratio of the sputtered gradient or gradient morphology film is controlled by adjusting the movement amplitude of the movable magnet group along the width direction, synchronously controlling the movement distance of the maximum etching rate position along the width direction and the time ratio of different stop positions.

3. The ruthenium-cobalt alloy target sputtering method according to claim 1, characterized in that: In step S3, by regulating the dwell time of the movable magnet group when it moves to different positions along the width direction, the dwell time of the maximum etching rate position when it moves to different positions along the width direction is synchronously controlled.

4. The ruthenium-cobalt alloy target sputtering method according to claim 1, characterized in that: In step S2, the movable magnet group includes several groups of magnets, and the several groups of magnets are respectively allowed to move in a direction perpendicular to the target surface, and the magnets are arranged with N poles and S poles facing upward alternately along the width direction.

5. The ruthenium-cobalt alloy target sputtering method according to claim 4, characterized in that: In step S3, the distance between each group of magnets and the target surface is controlled respectively so that the position of the maximum etching rate moves along the width direction.

6. The ruthenium-cobalt alloy target sputtering method according to claim 1, characterized in that: In the two long strip targets with different ruthenium and cobalt composition ratios, the content of ruthenium or cobalt is greater than or equal to 20%.

7. The ruthenium-cobalt alloy target sputtering method according to claim 1, characterized in that: The widths of the two long strip targets with different ruthenium and cobalt composition ratios are equal.

8. The ruthenium-cobalt alloy target sputtering method according to claim 7, characterized in that: The movement amplitude of the movable magnet group along the width direction is equal to the sum of the widths of two adjacent long strip targets.

9. The ruthenium-cobalt alloy target sputtering method according to claim 1, characterized in that: In S1, two long strip targets are alternately spliced and fixed on the upper surface of the target backing plate, and the movable magnet group is arranged below the target backing plate.

10. The ruthenium-cobalt alloy target sputtering method according to claim 1, wherein: The movement of the movable magnet group along the width direction is reciprocating movement.

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