JP2008088500A - Sputtering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sputtering apparatus which allows an eroded state of a target to be monitored without opening a vacuum chamber and does not need a facility for storing an erosion-monitoring means therein. <P>SOLUTION: This sputtering apparatus comprises: a vacuum chamber 11 of which the vacuum is kept and in which a predetermined gas is sealed off; a wafer stage 14 for holding a wafer 13 on which a thin film 12 is formed; a backing plate 16 for holding a target 15 which releases an ingredient for forming the thin film 12; a current-applying means 17 for applying a direct current to the target 15; a light displacement sensor 20 as the erosion monitoring means, which is installed in the wafer stage 14 and monitors the erosion of the target 15; and a moving means 19 which moves the light displacement sensor 20 in a predetermined range. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sputtering apparatus.

  When the erosion (erosion) of the target used in the sputtering apparatus proceeds, the member holding the target is sputtered, and there is a risk that a product to be sputtered will be defective. For this reason, it is common to monitor the erosion of the target and replace it with another target when the erosion amount exceeds a predetermined value.

  Conventionally, when measuring the amount of erosion of a target, first, the vacuum chamber (vacuum container) is opened to the atmosphere, and a new target is mounted in the vacuum chamber.

  At this time, in order to monitor the power applied to the target, the numerical value of the integrating wattmeter set in the DC power supply is set to 0 kW.

  Next, for example, a sputtering process is performed on a predetermined number of wafers, and when the integrated power value of the integrating wattmeter reaches a predetermined value, the vacuum chamber is opened to the atmosphere, and the amount of erosion of the target is measured.

  Based on the maximum value of the erosion amount measured here and the initial thickness of the target, the life of the target is predicted in a proportional relationship. Then, an integrated power value corresponding to the life of the target is calculated.

  Thereafter, sputtering is performed on a predetermined number of wafers, and the vacuum chamber is opened to the atmosphere, and the amount of erosion of the target is measured. Next, it is checked whether the relationship between the predicted life of the target and the integrated power value is correct.

  However, the conventional method has a problem that the vacuum chamber needs to be opened and closed a plurality of times, and the operation becomes complicated.

  Further, every time the vacuum chamber is opened, it is necessary to replace the shield part for maintaining the vacuum in the vacuum chamber. Furthermore, after closing the vacuum chamber, it was necessary to re-exhaust the internal air.

  Further, in order to remove the oxide film generated on the surface of the target when the vacuum chamber is opened, it is necessary to perform a pre-sputtering process called target cleaning. For this reason, there has been a problem that the operating rate of the sputtering apparatus is significantly hindered.

  In addition, since the target erosion amount is not directly measured, if the integrated power value is not reset to 0 kW at the initial stage of target installation for some reason, there is a problem that the target life is reached earlier than actual. .

  In addition, the integrated power value may be reset to 0 kW for some reason, and in this case, a target life longer than the actual life is set. In this case, there is a possibility that even the backing plate which is a target holding member is sputtered. In addition, there is a risk of product failure.

In order to solve the above problem, a sputtering apparatus that can monitor the erosion of the target as needed without opening the vacuum chamber has been proposed (for example, refer to Patent Documents 1 and 2). .
Japanese Patent Laid-Open No. 11-61403 JP 2002-60935 A JP-A-6-88223 Japanese Patent No. 2953940

  However, the sputtering apparatus capable of monitoring the erosion of the target without opening the conventional vacuum chamber has to be newly provided with a storage facility for storing the erosion monitoring apparatus attached to the outside of the vacuum chamber. . For this reason, there existed a problem that a sputtering device became large.

  Further, in order to prevent the spatter from adhering to the erosion monitoring device, it is necessary to provide a shutter facility. In this case, there is a possibility that new problems such as generation of particles from the shutter equipment and deterioration of exhaust characteristics may occur.

  The present invention has been made in view of such a problem, and can monitor erosion of a target without opening a vacuum chamber, does not require a storage facility for erosion monitoring means, and can suppress an increase in size of the apparatus. It is an object to provide a sputtering apparatus.

The present invention employs the following means in order to solve the above problems.
That is, the present invention
A vacuum chamber for holding a vacuum and enclosing a predetermined gas;
A thin film forming member holding means which is disposed in the vacuum chamber and holds a thin film forming member on which a thin film is to be formed;
A target holding means for holding a target that is disposed in a position facing the thin film forming member holding means in the vacuum chamber and releases a component that forms the thin film;
Current application means for applying a DC power source to the target;
Erosion monitoring means provided in the thin film forming member holding means for monitoring erosion of the target;
Moving means for moving the erosion monitoring means within a predetermined range;
Is provided.

  In the present invention, since the erosion monitoring means for monitoring the erosion of the target is provided in the thin film forming member holding means, the erosion can be monitored without opening the vacuum chamber. Further, it is not necessary to provide a storage facility for erosion monitoring means outside the vacuum chamber.

  Here, the erosion monitoring means can be configured to be shielded by the thin film forming member. With this configuration, it is possible to prevent the erosion monitoring unit from being sputtered without providing a shutter for shielding the erosion monitoring unit.

  The moving means may be configured to linearly move the target monitoring means from a position corresponding to the center of the target to a position corresponding to the edge of the target. With this configuration, erosion from the center of the target to the edge can be monitored.

  Further, it is preferable to have a rotating means for rotating the thin film forming member holding means. With this configuration, erosion can be monitored over the entire target.

  In addition, an alarm can be generated when the erosion amount is equal to or greater than a predetermined value. With this configuration, the progress of erosion can be recognized immediately.

  According to the present invention, since the erosion of the target can be monitored without opening the vacuum chamber, the labor for monitoring the erosion can be saved. Moreover, since it is not necessary to provide a storage facility for the erosion monitoring means outside the sputtering apparatus, it is possible to suppress the apparatus from becoming large.

  Hereinafter, a sputtering apparatus according to the present invention will be described in detail with reference to FIGS.

  FIG. 1 shows a sputtering apparatus 1 according to an embodiment of the present invention. The sputtering apparatus 1 holds a vacuum chamber 11 that holds a vacuum and is filled with a predetermined gas, and a wafer 13 that is disposed in the vacuum chamber 11 and holds a wafer 13 that is a thin film forming member on which a thin film 12 is to be formed. A wafer stage 14 that is a thin film forming member holding means, a backing plate 16 that is a target holding means that is disposed at a position facing the wafer stage 14 in the vacuum chamber 11 and holds a target 15 that releases components of the thin film 12; Current applying means 17 for applying a direct current to the target 15, an optical displacement sensor 20 that is provided on the wafer stage 14 and is an erosion monitoring means for monitoring erosion (erosion) of the target 15, and the optical displacement sensor 20 within a predetermined range. And moving means 19 for moving at the same time.

  Next, each of the above components will be described. Since it is the same as the conventional sputtering apparatus except for the following explanation, the detailed explanation is omitted.

  The vacuum chamber 11 is formed in a sealed container shape. A predetermined amount of, for example, argon gas is supplied as a process gas from the gas line 21 into the vacuum chamber 11.

  The air in the vacuum chamber 11 is sucked by the vacuum pump 23 through the exhaust port 22 and discharged to the outside. In FIG. 1, reference numeral 24 denotes a magnet that rotates around the center thereof, and reference numeral 25 denotes a valve that controls the supply amount of argon gas.

  A rotating means 26 such as a motor for rotating the wafer stage 14 around its center is provided below the wafer stage 14. As shown in FIG. 2, the wafer stage 14 is formed in a substantially circular shape.

  As shown in FIG. 3, the optical displacement sensor 20 includes a light emitting element 30 and a light receiving element 31. In the present embodiment, a semiconductor laser is used as the light emitting element 30. An optical position detection element is used as the light receiving element 31.

The optical displacement sensor 20 measures the erosion amount (erosion amount) t (see FIG. 5) of the target 15 based on the principle of triangulation. In the present embodiment, the accuracy required for measuring the erosion amount t of the target 15 is about 0.1 mm. On the other hand, the measurement resolution of a commercially available optical displacement sensor is 50 microns or less. Therefore, a commercially available optical displacement sensor can be used as the optical displacement sensor 20.

  In the present embodiment, the erosion amount t is represented by the distance from the surface 39a before the erosion occurrence, which is the reference surface of the target 15, to the surface 39b after the erosion occurrence.

  When light 35 is emitted from the light emitting element 30 of the optical displacement sensor 20, the light 35 is reflected by the target 15 and enters the light receiving element 31. Thereby, the erosion amount t of the target 15 is measured.

  As shown in FIG. 1, the optical displacement sensor 20 is movably inserted into a groove 14 a provided on the upper surface of the wafer stage 14. A transparent lid 14b is provided on the upper side of the groove 14a.

  The moving means 19 has an air cylinder 32, as shown in FIG. The air cylinder 32 has a tube-shaped main body 33 and a piston 34 that is taken in and out of the main body 33 by pressurized air supplied into the main body 33.

  The tip of the piston 34 is connected to the optical displacement sensor 20. By moving the piston 34 in and out of the main body 33, the optical displacement sensor 20 reciprocates linearly within a predetermined range 37 (see FIG. 2). In the present embodiment, the predetermined range 37 is set linearly from the vicinity of the center 14c of the wafer stage 14 to the vicinity of the edge 14d.

  When the piston 34 of the air cylinder 32 is extended from the main body 33 to the maximum, the light irradiation unit 30 a in the light emitting element 30 of the optical displacement sensor 20 is disposed at a position corresponding to the vicinity of the edge 15 a of the target 15.

  Then, the light 35 emitted from the light emitting element 30 of the optical displacement sensor 20 is irradiated in the vicinity of the edge 15 a of the target 15. Thereby, the erosion amount t in the vicinity of the edge 15a of the target 15 is measured. Note that reference numeral 31 a in FIG. 3 is a light receiving portion of the light receiving element 31.

  As shown in FIG. 4, when the piston 34 of the air cylinder 32 is inserted into the main body 33 to the end, the light irradiation part 30 a in the light emitting element 30 of the optical displacement sensor 20 is near the center 15 b of the target 15. It is arranged at a position corresponding to.

  Then, the light 35 emitted from the light emitting element 30 of the optical displacement sensor 20 is irradiated near the center 15 b of the target 15. Thereby, the erosion amount t near the center 15b of the target 15 is measured.

  As shown in FIG. 5, the erosion amount t of the target 15 is represented by a distance (depth) from the surface (reference surface) 39a of the target 15 before the erosion occurs to the surface 39b after the erosion occurs. Note that the symbol T in FIG. 5 is the remaining thickness of the target 15.

  Next, the operation of the sputtering apparatus 1 will be described. When the thin film 12 is formed on the wafer 13 by sputtering, the air in the vacuum chamber 11 is first exhausted by the vacuum pump 23 through the exhaust port 22 as shown in FIG. Thereby, the pressure in the vacuum chamber 11 is maintained at about 1.3 × 10 −6 Pa to 1.3 × 10 −7 Pa.

Next, a process gas, for example, argon gas, supplied through the gas line 21 is introduced into the vacuum chamber 11 and the pressure in the vacuum chamber 11 is maintained at about 1.3 × 10 −1 Pa.

  Next, a direct current is applied from the current application means 17 to the target 15. Thereby, a magnetron discharge is generated, the argon gas sealed in the vacuum chamber 11 is ionized, and the components of the target 15 are sputtered on the wafer 13. Thereby, the thin film 12 is formed on the wafer 13.

  As the sputtering process proceeds, the erosion amount t of the target 15 becomes the largest in the portion where the horizontal magnetic field of the magnet 24 is the strongest. This is because the horizontal magnetic field is less likely to capture process gas such as argon gas than the vertical magnetic field.

  In this embodiment, as shown in FIG. 6, the target 15 is formed in a circular shape. The magnet 24 is also formed in a circular shape. Furthermore, in order to equalize the erosion of the target 15, the magnet 24 is rotated by a motor or the like with the center as the center of rotation. For this reason, the erosion of the target 15 occurs on a substantially concentric circle.

  In this way, the wafer 13 for which the sputtering process has been completed is replaced with another wafer 13 without opening the vacuum chamber 11 by automatic replacement means (not shown). Then, a sputtering process is performed on a predetermined number of wafers 13.

  While the wafer 13 is being sputtered, the optical displacement sensor 20 and the transparent lid 14 b are shielded by the wafer 13. Accordingly, it is possible to prevent the optical displacement sensor 20 and the lid 14b from being sputtered.

  After the sputtering processing of a predetermined number (for example, about 50 to 100 wafers) of the wafers 13 is completed, the target is detected by the optical displacement sensor 20 with the wafers 13 on the wafer stage 14 removed as shown in FIG. The erosion amount t of 15 is directly measured. In the present embodiment, the erosion amounts t at a plurality of locations of the target 15 are measured, and the maximum value is extracted.

  In measuring the erosion amount t of the target 15, the light 35 emitted from the light emitting element 30 of the optical displacement sensor 20 is irradiated to a predetermined position of the target 15 as shown in FIG. 5. The light 35 is reflected by the target 15 and enters the light receiving element 31.

  The output of the light receiving element 31 is supplied to an external calculation unit 36. In the calculation unit 36, the erosion amount t of the target 15 is calculated based on the input from the light receiving element 31. Further, the calculation unit 36 calculates the remaining thickness (remaining thickness) T of the target 15 based on the erosion amount t.

  The erosion amount t of the target 15 is measured while moving the optical displacement sensor 20 by the moving means 19. In the present embodiment, as shown in FIG. 2, the optical displacement sensor 20 linearly moves within a predetermined range 37 from the vicinity of the center 14c of the wafer stage 14 to the vicinity of the edge 14d.

  As shown in FIG. 6, the predetermined range 37 is set so that the erosion amount t can be measured by the optical displacement sensor 20 along the diameter line 38a of the use range 38 used for the sputtering process of the target 15. .

Further, in the present embodiment, the erosion amount t is measured while the wafer stage 14 rotates intermittently by a predetermined angle around the center 14c and the optical displacement sensor 20 moves linearly. Thus, the erosion amount t of the entire sputtering usage range 38 of the target 15 is measured.

  FIG. 8 shows the measurement result of the erosion amount t when aluminum is used as the material of the target 15.

  FIG. 9 shows a measurement result of the erosion amount t when titanium is used as the material of the target 15. 8 and 9, the horizontal axis represents the distance from the center of the target, and the vertical axis represents the erosion amount t.

  As can be seen from FIGS. 8 and 9, the erosion amount t varies depending on the distance from the center 15 b of the target 15. Further, since the target 15 is rotating, the erosion amounts t on the left side and the right side of the center 15b are the target shape.

  An alarm is generated when the maximum value of the erosion amount t of the target 15 exceeds a predetermined value. In this embodiment, when the erosion amount t reaches an alarm value (a predetermined numerical value set in advance) that is a predetermined value, a signal exchange unit connected to the optical displacement sensor 20 outputs a target exchange signal as an alarm. (Predetermined signal) is generated.

  By generating this target replacement signal, it is possible to immediately recognize that the life of the target 15 has reached the end of life and replace the target 15. As a result, it is possible to prevent a phenomenon in which components of the backing plate 16 holding the target 15 are released. The alarm value can be arbitrarily set according to the initial thickness T of the target 15 and the thickness of the backing plate 16.

  FIG. 10 shows a flowchart of the sputtering process. Here, sputtering processing is first performed on the wafer (S1). Next, it is determined whether or not the sputtering process has been completed for a predetermined number of wafers (S2).

  If it is determined in step (S2) that the sputtering process for the predetermined number of wafers has not been completed, the process of step (S1) is performed next.

  If it is determined in step (S2) that the sputtering process has been completed for a predetermined number of wafers, the target erosion amount is measured (S3). Next, the measured erosion amount is displayed (S4).

  Next, it is determined whether or not the erosion amount is equal to or greater than a predetermined alarm value (S5). If it is determined in step (S5) that it is less than the alarm value, then the processing from step (S1) onward is performed.

  If it is determined in step (S5) that the erosion amount is greater than or equal to the alarm value, an alarm is then generated (S6). Thereby, the process ends.

  As described above, according to the sputtering apparatus 1 of the present invention, the erosion amount t of the target 15 can be directly measured by the optical displacement sensor 20 without opening the vacuum chamber 11. Therefore, the number of work steps for monitoring erosion can be reduced.

  In addition, it is possible to prevent the phenomenon of components of the backing plate 16 being skipped due to an erroneous operation of indirect measurement using the integrated power value in the prior art.

  In addition, since the life of the target 15 can be accurately determined and the target 15 can be effectively used up to the limit of the life of the target 15, it is possible to greatly contribute to the improvement of productivity by reducing the running cost.

  Moreover, since it is not necessary to provide a storage facility for the optical displacement sensor 20 outside the vacuum chamber 11, it is possible to suppress the sputtering apparatus 1 from becoming large.

  Further, since the optical displacement sensor 20 is shielded by the wafer 13 during the sputtering process, it is not necessary to provide a shutter or the like for shielding the optical displacement sensor 20. Therefore, the configuration can be simplified.

  Further, the optical displacement sensor 20 is moved linearly by the moving means 19, and the optical displacement sensor 20 is rotated about the center 14 c of the wafer stage 14 by the rotation of the wafer stage 14.

  Thereby, the erosion amount t can be measured over the entire sputtering use range 38 in the target 15. Therefore, the reliability of erosion monitoring is increased.

  In the above embodiment, the moving means 19 of the optical displacement sensor 20 is constituted by the air cylinder 32. However, as shown in FIG. 11, a moving means 40 constituted by gears and a rack can be used.

  The moving means 40 is provided with a rack 41 having a predetermined length below the optical displacement sensor 20. A gear 42 meshed with the rack 41 is provided on the bottom surface of the optical displacement sensor 20 as shown in FIG. The gear 42 is rotated by a motor (not shown) provided in the optical displacement sensor 20.

  Moreover, as shown in FIG. 13, the moving means 50 comprised with a screw and a nut can be used. The moving means 50 includes a screw 51 disposed below the optical displacement sensor 20 and a motor 52 that rotates the screw.

  A nut 53 screwed into a screw 51 is provided on the bottom surface of the optical displacement sensor 20. A rail 54 is provided below the optical displacement sensor 20, as shown in FIG.

  In the above embodiment, the optical displacement sensor 20 is used as the erosion monitoring means. However, as the erosion monitoring means, various types of radar sensors such as millimeter wave radar and microwave radar, various optical sensors such as proximity azimuth sensors, Alternatively, a capacitance sensor can be used.

  The sputtering apparatus of the present invention includes the following additional items.

[Others]
The present invention can be specified as follows.

(Supplementary note 1) A vacuum chamber for holding a vacuum and enclosing a predetermined gas;
A thin film forming member holding means which is disposed in the vacuum chamber and holds a thin film forming member on which a thin film is to be formed;
A target holding means for holding a target that is disposed in a position facing the thin film forming member holding means in the vacuum chamber and releases a component that forms the thin film;
Current application means for applying a direct current to the target;
Erosion monitoring means provided in the thin film forming member holding means for monitoring erosion of the target;
Moving means for moving the erosion monitoring means within a predetermined range;
A sputtering apparatus comprising:

  (Additional remark 2) The said erosion monitoring means is a sputtering apparatus of Additional remark 1 which measures the said erosion amount based on the distance from the reference plane to the surface of the said target.

  (Supplementary note 3) The sputtering apparatus according to supplementary note 1, wherein the erosion monitoring means is shielded by the thin film forming member.

  (Supplementary note 4) The sputtering apparatus according to supplementary note 1, wherein the erosion monitoring means is a millimeter wave radar, a microwave radar, an optical sensor, a proximity azimuth sensor, or a capacitance sensor.

  (Supplementary note 5) The sputtering apparatus according to supplementary note 1, wherein the moving means linearly moves the target monitoring means from a position corresponding to the center of the target to a position corresponding to an edge of the target.

  (Additional remark 6) Sputtering apparatus of Additional remark 1 which has a rotation means to rotate the said to-be-formed-film formation member holding means.

  (Supplementary note 7) The sputtering apparatus according to supplementary note 1, wherein an alarm is generated when the erosion amount is a predetermined value or more.

It is sectional drawing which shows the sputtering device which concerns on this invention. It is a top view which shows the wafer stage which concerns on this invention, and is AA sectional drawing of FIG. It is sectional drawing which shows the state by which the erosion monitoring apparatus which concerns on this invention is arrange | positioned in the position corresponding to the edge of a target. It is sectional drawing which shows the state by which the erosion monitoring apparatus which concerns on this invention is arrange | positioned in the position corresponding to the center of a target. It is sectional drawing which shows the measuring method of the amount of erosion which concerns on this invention. It is a figure which shows the sputter | spatter use range of the target which concerns on this invention, and is B arrow view of FIG. It is a figure which shows the erosion measuring method of the target which concerns on this invention, and is a figure which shows the state which removed the wafer. It is a figure which shows the measurement result of the erosion amount at the time of using aluminum for the material of the target which concerns on this invention. It is a figure which shows the measurement result of the erosion amount at the time of using titanium for the material of the target which concerns on this invention. It is a flowchart which shows the sputtering process which concerns on this invention. It is a figure which shows another moving means which concerns on this invention, and is a top view which shows the moving means comprised with the gearwheel and the rack. It is a side view which shows the moving means comprised with the gearwheel and rack which concern on this invention, and is C arrow line view of FIG. It is a figure which shows another moving means which concerns on this invention, and is a front view which shows the moving means comprised with the screw and the nut. It is a side view which shows the moving means comprised with the screw and nut which concern on this invention, and is D arrow line view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sputtering apparatus 11 Vacuum chamber 12 Thin film 13 Wafer (Thin film forming member)
14 Wafer stage (Thin film forming member holding means)
14a Groove 14b Transparent lid 14c Center of wafer stage 14d Outer peripheral edge (edge) of wafer stage
15 target 15a edge of target 15b center of target 16 backing plate (target holding means)
17 Current application means 19 Movement means 20 Optical displacement sensor (erosion monitoring means)
21 Gas Line 22 Exhaust Port 23 Vacuum Pump 24 Magnet 26 Rotating Means 30 Light Displacement Sensor 30a Light Irradiation Unit 31 Light Displacement Sensor Light Receiving Element 31a Light Receiving Unit 32 Air Cylinder 33 Main Body 34 Piston 35 Irradiation Light 36 Calculation Unit 37 Predetermined range 38 Target sputtering range 38a Diameter line 39a Target surface (reference plane) before erosion occurs
39b Target surface after occurrence of erosion 40 Moving means 41 Rack 42 Gear 50 Moving means 51 Screw 52 Motor 53 Nut 54 Rail

Claims (5)

A vacuum chamber for holding a vacuum and enclosing a predetermined gas;
A thin film forming member holding means which is disposed in the vacuum chamber and holds a thin film forming member on which a thin film is to be formed;
A target holding means for holding a target that is disposed in a position facing the thin film forming member holding means in the vacuum chamber and releases a component that forms the thin film;
Current application means for applying a DC power source to the target;
Erosion monitoring means provided in the thin film forming member holding means for monitoring erosion of the target;
Moving means for moving the erosion monitoring means within a predetermined range;
A sputtering apparatus comprising:   The sputtering apparatus according to claim 1, wherein the erosion monitoring unit is shielded by the thin film forming member.   The sputtering apparatus according to claim 1, wherein the moving unit linearly moves the erosion monitoring unit from a position corresponding to the vicinity of the center of the target to a position corresponding to the vicinity of the edge of the target.   The sputtering apparatus according to claim 1, further comprising a rotating unit that rotates the thin film forming member holding unit.   The sputtering apparatus according to claim 1, wherein an alarm is generated when the erosion amount is a predetermined value or more.

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