TW445515B - Physical vapor phase deposition device capable of producing a thin film with uniform thickness on the surface of a semiconductor chip - Google Patents

Abstract

The present invention provides a physical vapor phase deposition device capable of producing a thin film with uniform thickness on the surface of a semiconductor chip. The device comprises a vacuum chamber which can be vacuumed and filled with Ar gas to produce Ar ions; a chip pad formed in the vacuum chamber for carrying a round semiconductor chip; a round metal target formed in the vacuum chamber and located above the semiconductor chip; a ring coil formed in the vacuum chamber and located between the metal target and the semiconductor chip, the ring coil having the same material as the metal target; and a voltage controller for controlling the voltages of the metal target, the chip pad, and the ring coil. When performing a physical vapor deposition, the voltage controller respectively generates a preset voltage difference between the metal target and the chip pad, and between the coil and the chip pad. Therefore, the Ar ions in the vacuum chamber can bombard the metal target and the ring coil, respectively, to release metal atoms, so as to uniformly sputter on the center and edge of the semiconductor chip and thus produce a thin film with uniform thickness on the surface of the semiconductor chip.

Description

4 4b 5 1 5 5. Description of the invention (1) The present invention provides a physical vapor deposition (PVD) device, especially a PVD device capable of generating a thin film of uniform thickness on the surface of a semiconductor wafer. . Physical vapor deposition of semiconductor processes is used to form metal thin films on the surface of semiconductor wafers. A layer of a well-structured metal film must not have voids remaining in the metal film 'and the thickness of the metal film must have good uniformity ° Please refer to Figure 1, which is a schematic diagram of the structure of a conventional PVD device 10 β The conventional PVD device 10 includes a vacuum chamber 12 which can be evacuated to a low vacuum and passed through argon (Aron) to generate argon ions 18. A wafer holder 14 is used to hold a circular half Guide the wafer 16 'and a round metal handle I ?. The PVD device 10 will generate a built-in electric field. The argon ions 18 in the vacuum chamber 12 impact the metal target 17 due to the built-in electric field, causing ion bombardment, and then knock out metal atoms 19 on the surface of the metal target. , So that the metal atoms 19 fall to the semiconductor wafer 16 located below the metal target 17, and a metal thin film 20 is formed on the surface of the semiconductor wafer 16. Please refer to Fig. 2. Fig. 2 is a schematic circle of the PVD device 10 shown in Fig. 1 forming a metal thin film 20 on the surface of the semiconductor wafer 16. The circle in Fig. 2 represents metal atoms 19 generated by the metal target 17 due to the impact of ions. The arrow indicates the falling direction of the metal atom 19. PVD device 10 is used to

Page 5 4455 1 5 V. Description of the invention (2) When the semiconductor wafer 16 is in the PVD process, the falling direction of the metal atoms 19 is very random and irregular, and is formed at the corner of the top of the groove 22 The metal thin film at the place is prone to overhang, and the cavity 26 is easily formed in the recess 24 with a low aspect ratio. Therefore, the metal atom 19 generated in the PVD device 10 forms a metal thin film. Poor hole filling ability. Please refer to FIG. 3 and FIG. 4. FIG. 3 is a schematic diagram of a conventional PVD device 30 with a collimator. FIG. 4 is a schematic diagram of a metal thin film 40 formed on the surface of a semiconductor wafer 36 by the PVD device 30 shown in FIG. 3. The main difference between the PVD device 30 and the PVD device 10 is that the PVD device 30 is additionally provided with a collimation tube 38 composed of a plurality of parallel long tubes side by side to block the surface of those round metal targets 37 that are scattered but not vertical. Falling metal atoms. When using the PVD device 30 to perform a PVD process on a semiconductor wafer 36 having a groove, 'most of the messy metal atoms will be blocked in the collimator tube 38, and the metal atoms 19 falling on the surface of the semiconductor wafer 36 are vertical Falling, so that the metal thin film 40 generated on the surface of the semiconductor wafer 36 has almost no overhang phenomenon. Therefore, the metal atoms 19 generated in the PVD device 30 have a good hole filling ability when forming a metal thin film. Since most of the metal atoms of Ling IL will be blocked in the collimator tube 38, the collimator tube 38 must be cleaned or replaced regularly, which increases the time and cost required for the PVD process. Please refer to FIG. 5. FIG. 5 is a schematic diagram of a conventional ionized PVD device 50. The conventional ionized PVD device 50 and PVD devices 10 and 30 are mainly

Page 6 V. Description of the invention (3) The difference is that the ionized pVD device 50 includes a ring wire 58 provided between the metal handle 57 and the wafer holder 54. When the pyjj device 50 performs the pyj) process, the cylindrical area surrounded by the toroidal coil 58 will generate a magnetic field due to the local-frequency AC voltage applied to the toroidal coil 58. In addition to the impact of the built-in electric field, the argon ions in the vacuum chamber 52 will impact the circular metal target 57 to generate metal atoms in the circular metal target 57. At the same time, the argon ions will perform a spiral motion by the action of the magnetic field, thereby causing argon Ions are prone to collide with falling metal atoms, reducing the mean free path (meari f ree 叩 ") of the argon ions and charging the metal atoms. The charged metal atoms are affected by the vertical built-in electric field of the PVD device 50. Increasing the dropping speed in the vertical direction and relatively reducing the dropping speed in other directions, so the metal atoms generated in the IMP PVD device 50 have a good hole filling ability. The thickness of the metal thin film is smaller than the thickness of the metal thin film in the center, so that the uniformity of the metal thin film prepared by the IMP PVD device 50 is not good. Please refer to Figure 26, which is a schematic diagram of the metal formed on the conductor wafer 56. Because of the size of the IMPPVD device 50, the size of the loop coil 58 shown in FIG. 5 is the distribution of the IMP PVD device 50 in the thickness of the semi-thin film 57 along the aa line of the vacuum chamber 5 2 Small is usually fixed with a certain range limit, which will lead to sinking. Therefore, the main purpose of the present invention is to provide a new pV device. The metal atoms generated in the PVD device of the present invention have better hole filling ability when forming a metal thin film. And the formed metal film has a uniform thickness

Page 445515 V. Description of the invention (4) Degree. Brief Description of the Figures Figure 1 is a schematic structural diagram of a conventional PVD device. FIG. 2 is a schematic diagram of forming a metal thin film on the surface of a semiconductor wafer by the PVD device shown in FIG. 1. FIG. Figure 3 is a schematic structural diagram of a conventional PVD device with a collimator. FIG. 4 is a schematic diagram of forming a metal thin film on the surface of a semiconductor wafer by the PVD device shown in FIG. 3. FIG. 5 is a schematic structural diagram of a conventional ionization PVD device. Figure 6 shows the distribution of the thickness of the metal thin film formed on the surface of the semiconductor wafer by the IMP PVD device shown in Figure 5 along the a-a line. FIG. 7 is a schematic structural diagram of a PVD device according to the present invention. FIG. 8 is a schematic structural diagram of a PVD device according to another embodiment of the present invention. Symbols shown in the figure 70, 80 vacuum chamber 74, 84 wafer holder N, 86 semiconductor wafer 78, 88 toroidal coil 75, 85 voltage controller Η, 87 circular metal target 90 toroidal metal target Please refer to Figure 7, Figure 7 This invention pVD device 70 invention PVD device contains a right acre * grid 70 minutes called t ^ ii ^ there is a vacuum chamber 72 'which can be evacuated and passed into the mill to produce argon ions 18, a ^. Argon

The Ba sheet holder 74 ′ is set in the vacuum chamber 72 and used

Page 8, M45R 1 r__ 5. Description of the invention (5) To hold a circular semiconductor wafer 76 ′ A circular metal target π, located in the vacuum test 72 and directly above the semiconductor wafer 76, a toroidal coil 78. It is located in the vacuum chamber 72 and located between the circular metal target 77 and the semiconductor wafer 76 'and a voltage controller 75' is used to control the voltage of the circular metal target 77, the wafer holder 74 and the toroidal coil * 78. The toroidal coil 78 and the circular metal target 77 are made of the same material, such as copper (CU), titanium (Ti), or tantalum (Ta). When performing PVD, the pressure of the argon gas in the vacuum chamber 72 must be maintained within the range of 30 to 50 mtorr. When the physical vapor deposition is performed in the PVD device 70 of the present invention, the voltage controller 75 applies a DC voltage to the circular metal rake door, the toroidal coil 78 and the wafer holder 74 'and causes the circular metal target 77 and the wafer to A predetermined potential difference can be formed between the holders 74 and between the toroidal coil 78 and the wafer holder 74. Therefore, the circular metal target 77 is bombarded with argon ions 18 in the vacuum chamber 72 to release metal atoms 19 and is sputtered approximately at the center portion of the semiconductor wafer π ', and the argon ions 18 in the vacuum chamber 72 are bombarded to the torus 78 causes it to release metal atoms 19 and is roughly sputtered on the edge portion of the semiconductor wafer 76. Since the material of the toroidal coil 78 is the same as that of the circular metal target 77, the toroidal coil 78 疋 is used as a sub-metai target to release metal atoms 19 to destroy silver on the semiconducting wafer 76. The edge part, so that the surface of the semiconducting wafer 76 will form a layer of metal with a uniform thickness. In addition, the voltage controller 75 will apply a high-frequency AC voltage to the toroidal coil 78 to generate a magnetic field, so that the inside of the vacuum chamber 72 Argon 18

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The rotational movement further causes the argon ion 18 to easily collide with the metal atom 20 generated by the circular metal target 77 to charge the metal atom 19. Therefore, the charged metal atoms 19 will be affected by the built-in electric field in the PVD device 70, increasing the falling speed in the vertical direction and relatively reducing the falling speed in other directions, so that when the semiconductor wafer 76 forms a metal thin film, Best hole filling ability. When the PVD device 70 of the present invention performs physical vapor deposition, it is divided into two control stages: the first stage is to use metal atoms generated by the circular metal target 77 to perform plating to complete the sputtering of the central portion of the semiconductor wafer 76; In the second stage, metal atoms generated by the toroidal coil 78 are used for sputtering, so as to complete sputtering on the edge portion of the semiconductor wafer 76. The control methods of these two phases are respectively explained as follows: Phase 1: The voltage controller 75 is applied to the circular metal stem 77 and the wafer holder 74 with a DC voltage and is continuously applied to the toroidal coil 78 with a high-frequency AC voltage. . The DC voltage applied to the circular metal target 77 is -wo to -1 000 volts, and the DC voltage applied to the wafer holder 74 is -100 to -300 volts. The frequency of the high-frequency AC voltage applied to the coil 50. As long as the ion transition frequency is greater than 1 to 3 MHz, the frequency of the high-frequency AC voltage used in the general industry is 13, 56MHz, and the power of the high-frequency AC voltage applied to the coil 50 is 100 to 500 watts. At this stage, all metal atoms in the vacuum chamber 72 are generated by the circular metal target 77, and these metal atoms are easily formed by collisions with argon ions through the columnar area surrounded by the annular coil 78

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The charged metal atom 19 has a better hole filling ability when the semiconductor wafer 76 forms a metal thin film. V The second stage: After the first stage is continued for a period of time, a DC voltage is applied to the toroidal coil 78 and the wafer holder 74. The DC voltage applied to the toroidal coil 78 is -10 to -300 volts. After the first stage, the thickness of the edge portion of the semiconductor wafer 76 has been sputtered to a certain degree. In the second stage, the ring coil 78 is added to generate metal atoms. The metal atoms in the vacuum chamber 72 are not only formed by the circular metal target 77 but also by the ring shape. The coil 78 is generated to increase the thickness of the metal thin film on the edge portion of the semiconductor wafer 76, so that the surface of the semiconductor wafer 76 can form a metal thin film with a uniform center and edge thickness. 1 Please refer to FIG. 8, which is a schematic diagram of a PVD device 80 according to another embodiment of the present invention. The toroidal coil 78 in the PVD device 70 provides both the magnetic field and the secondary metal target, while the PVD device 80 separates the magnetic field provider from the secondary metal, and can also achieve the purpose of making the thickness of the metal thin film uniform. The main difference between the PVD device 80 and the PVD device 70 is that the PVD device 80 includes an annular metal stem 90 provided in the vacuum trap 82 and located between the toroidal coil μ and the semiconductor wafer 86. The material of the ring metal target 90 is the same as that of the circular metal handle 87, and the material of the ring coil 88 need not be the same as that of the circular metal holder 87. A voltage controller 85 of a PVD device 80 is used to control the voltage between the circular metal target 87, the ring coil 88, the ring metal target 90, and the wafer holder 84. When the PVD device 80 performs physical vapor deposition, the voltage controller 85 will

Such as 445 5 V. Description of the invention (8) Apply a DC voltage to the circular metal stem 8 7, the annular metal stem 90 and the wafer holder 84 with the circular metal target 87 and the wafer holder 84, and Each of the ring metal I & 90 and the wafer holder 84 generates a predetermined potential difference. The argon ions 18 in the vacuum grabbing 8 2 will bombard the circular metal target 87, so that the circular metal target 87 releases metal atoms and is roughly sputtered on the center portion of the semiconductor wafer 76. In addition, the argon ions 18 in the vacuum chamber 82 will bombard the ring metal stem 90, so that the ring metal target 90 releases metal atoms and is roughly sputtered on the edge portion of the semiconductor wafer 86. The PVD device 80 is also divided into two control stages when performing physical vapor deposition. In the first stage, PVD is performed using only the circular metal target 87 instead of the ring metal target 90, and the voltage controller 85 also applies a high-frequency chirp voltage to the ring coil 88 at the same time to make the gas ions 18 easy to fall. The metal atoms collide and the metal atom 19 is charged. The metal atoms 19 fall vertically 'so that when the semiconductor wafer 86 forms a metal thin film, it will have better hole filling ability. In the second stage, not only the circular metal stem 8γ but also the ring-shaped metal target 90 'are used to increase the thickness of the metal thin film at the edge portion of the semiconductor wafer 86'. Therefore, a uniform metal thin film can be formed on the surface of the semiconductor wafer 86. Compared with the conventional PVD device, the PVD device 70 of the present invention has a ring-shaped coil, so that the metal thin film formed on the surface of the semiconductor wafer is filled well. In addition, the present invention uses the same toroidal coil as the surface metal target material or additionally sets a toroidal metal stem as a secondary metal to increase the thickness of the metal thin film that is chained to the edge portion of the semiconductor wafer to form the surface of the semiconductor wafer.

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Claims (1)

5 VI. Application Patent Scope 1. A physical vapor deposition (PVD) device 'which includes: a vacuum chamber' which can be evacuated and passed through argon (Ar) gas to generate argon Ions; a wafer holder provided in the vacuum chamber for receiving a circular semiconductor wafer; a circular metal target provided in the vacuum chamber and above the semiconductor wafer; a circular wire coil, It is located in the vacuum chamber and is located between the metal target and the semiconductor wafer, the material of which is the same as the metal target; and a voltage controller for controlling the voltage of the metal target, the wafer holder and the coil; During physical vapor deposition, the voltage controller applies a DC voltage to the metal target, the coil, and the wafer holder, and separates the metal target from the wafer holder and between the coil and the wafer holder. Generating a predetermined potential difference, so that argon ions in the vacuum chamber bombard the metal target to release metal atoms and sputter roughly on the central portion of the semiconductor wafer, and bombard the coil And which releases the metal atoms sputtered Roughly edge portion of the semiconductor wafer such that a surface of the semiconductor wafer to produce a uniform thickness of the metal thin film. 2. The physical vapor deposition device according to item 1 of the patent application scope, wherein the voltage controller first applies a DC voltage to the metal target to complete the sputtering of the central portion of the semiconductor wafer, and then applies the DC voltage. to Page M, 4 45 5 1 5 6. Scope of patent application The far line line is above to complete the sputter plating of the edge portion of the semiconductor watchdog. 3- As the first item in the scope of the patent application, the name 4 Tian X ja * ^ @ S & Caimu deposition device, in which the metal shoulder scapular herd soldiers produced by the use of the metal target are dried on the coil of interest. The argon in the vacuum chamber: AC voltage applied to the raw gold-gold atoms collided and allowed to dry out the sons formed in the semiconductor wafer to form the limb: the charged metal hole. When the metal film is cut, it will have a better filling, Yu Fu Lu, pressure control soil, "Ϊ 键 键 the semiconductor wafer in the semiconductor wafer such as the scope of patent application of the physical vapor deposition device No. 3, where the physical During vapor deposition, the frequency of the high-frequency AC voltage applied to the coil by the voltage controller is 13, 56 MHz ', and the power of the high-frequency AC voltage is 100 to 500 watts. 5. The physical vapor deposition device according to item 1 of the patent application scope, wherein the metal stem is made of copper (Cu), titanium (Ti) or tassel (Ta). 6. For example, a physical vapor deposition device of the scope of application for a patent, wherein the pressure of the argon gas in the vacuum chamber is maintained at 30 to 50 mtorr when performing physical vapor deposition. The physical vapor deposition device of the first scope of the patent, wherein when the physical vapor deposition is performed, the DC voltage applied to the coil by the voltage controller is Page 15 VI. Applying for a voltage · The voltage system is -100 to -300 volts' The DC voltage applied to the metal stem is -500 to -1000 volts, and the DC voltage applied to the wafer holder is -100 to -300 volts. 8. A physical vapor deposition device comprising:-a vacuum chamber 'which can be evacuated and passed through an argon (Ar) gas to generate a son; a B-piece holder' set in the vacuum chamber 'for receiving A circular semiconductor wafer is placed; a circular metal is placed in the vacuum chamber and above the semiconductor wafer; a ring-shaped metal is placed in the vacuum chamber and is located in the circular gold stem and the semiconductor wafer In between, its material is the same as the circular metal target; and a voltage controller 'is used to control the voltage of the two metal target and the wafer holder; wherein during physical vapor deposition, the voltage controller uses a DC voltage It is applied on the two metal target and the wafer holder, and a predetermined potential difference is generated between the circular metal target and the wafer holder and between the annular metal target and the wafer holder, so that the vacuum chamber Internal argon ions bombard the circular metal target to release metal atoms and sputter roughly on the central portion of the semiconductor wafer, and bombard the ring metal target to release metal atoms and sputter on the roughly Edge portions of the conductor so that the wafer surface of the semiconductor wafer to produce a uniform thickness _ Page 丨 6 4455 1 5 Patent application scope metal thin film 9. For example, the physical vapor deposition device of the patent application scope item 8, wherein the voltage controller will first apply a DC voltage to the circular metal stem to complete Sputtering at the central portion of the semiconductor wafer, and then applying a DC voltage to the annular metal target to complete sputtering at the edge portion of the semiconductor wafer. 10. If the physical vapor deposition device of item 8 of the patent application scope further includes a wire 圏 'electrically connected to the voltage controller and located in the vacuum chamber and located between the circular metal target and the annular metal target In the meantime, when metal atoms generated by the circular metal target are used to sputter the central portion of the semiconductor wafer, the voltage controller will apply a high-frequency AC voltage to the line coil to make the inside of the vacuum chamber The argon ions easily collide with and charge the metal atoms generated by the circular metal stem, and the charged metal atoms will have better hole filling ability when the semiconductor wafer forms the metal thin film. 11. For example, the physical vapor deposition device of the scope of application for patent No. 10, wherein when performing physical vapor deposition, the frequency of the high-frequency AC voltage applied by the voltage controller to the coil is 13.56 MHz, and the high-frequency The power of the AC voltage is 100 to 500 watts. Β 12 · For example, the physical vapor deposition device of item 8 of the scope of patent application, wherein the two ^ 445515 6. The scope of the patent application metal target is copper (Cu), titanium ( Ti) or tantalum (Ta). 13. The physical vapor deposition device according to item 8 of the scope of patent application, wherein the pressure of the argon gas in the vacuum chamber is maintained at 30 to 50 mt 〇rr β during successive physical vapor deposition. The physical vapor deposition device of the range item 8, wherein when the physical vapor deposition is performed, the DC voltage applied by the voltage controller to the ring-shaped metal holder is -100 to -300 volts, and is applied to the circular metal. The DC electric dust is -500 to -100 volts, and the DC voltage applied to the wafer holder is -100 to -300 volts.