JP2674995B2 - Substrate processing method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and apparatus for processing a sample by plasma generated in a processing chamber evacuated to vacuum, and particularly to forming a fine pattern on the surface. The present invention relates to a substrate processing method and apparatus suitable for processing a semiconductor substrate at high speed and uniformly. [Prior Art] As a prior art closest to the present invention, US Pat.
There are 5,394 specifications and drawings, JP-A-60-121268, and JP-A-61-87868. As a conventional high-speed thin film forming method by sputtering, as described in U.S. Pat. No. 3,325,394 and drawings, JP-A-60-121268, a target electrode and a substrate electrode are arranged to face each other, and two sets of magnetic devices are arranged. In some cases, a cusp magnetic field is formed by this to confine the plasma between the target and the substrate.
The above-mentioned technique is to confine the plasma of the atmospheric gas generated by the electric field applied to the target electrode on the target electrode in a wide range and at high density by the cusp magnetic field, thereby increasing the utilization efficiency of the target and improving the deposition rate. . Further, as described in JP-A-61-87868, in an electrode configuration using a cusp magnetic field, a negative voltage is applied to the substrate electrode to cause ions to collide with the thin film surface adhered and deposited on the substrate surface, and the film surface is re-sputtered. There is a bias sputtering method which improves the migration property of the adhered particles by applying energy by colliding with the adhered particles or applying energy. The above-mentioned technique confine high-density plasma on the wafer by the cusp magnetic field, so that a large amount of ions can be made to collide with the substrate surface, and the re-sputtering and migration performance of the film-forming surface is improved. [Problems to be Solved by the Invention] Although the above-mentioned conventional techniques are excellent in film formation speed, target utilization efficiency, improvement of the amount of ions flowing into the substrate, etc., the target electrode and the substrate electrode are opposed to each other in a cusp magnetic field. Since the magnetic lines of force formed by the magnetic device on the substrate side are pressed against the front face of the target, the magnetic lines of force formed by the magnetic device on the substrate side are focused on the center of the substrate electrode and traverse the substrate. Charged particles in plasma, especially electrons with a small mass, perform cyclotron motion along magnetic field lines in a magnetic field. Therefore, the electrons in the plasma are concentrated and incident on the center of the substrate along the lines of magnetic force generated by the magnetic device on the substrate side. Similar to this, Journal of Applied Physics Vol.34 No.4 (13.4), pages 760 to 768 (1963).
963) PP 760-768). According to the above-mentioned document, when the substrate is used as an anode to form a film by sputtering, the current is concentrated in the central portion of the substrate, and the temperature of this portion is abnormally increased. Figure 6 shows the results of measurements of the incident electron energy density and incident ion current density on the substrate in our experiments. As a result, it became clear that concentrated injection of high-energy electrons occurred in the central part of the substrate, and the ion current was twice as concentrated in the central part as in the peripheral part. This causes problems such as melting of the central portion and non-uniformity of film quality especially when a low melting point material such as Al is formed into a film. Furthermore, even in the bias sputtering method in which a negative voltage is applied to the substrate electrode and ions are made incident on the substrate surface, with the electrons concentrated in the central portion on the substrate electrode,
The incident ion density was also high in the central part, causing non-uniformity of the bias power, and in addition to the problem of abnormal temperature rise in the central part, the migration performance depending on the bias power varied depending on the position, and there was a problem in film formation reliability. An object of the present invention is to prevent high-energy electrons from being concentratedly injected into the central part of the substrate from the high-density plasma generated in the magnetic field, and to make the high-density plasma generated in the magnetic field uniform over the entire surface of the substrate. It is an object of the present invention to provide a substrate processing method and apparatus capable of performing various kinds of processing. [Means for Solving the Problem] The above-mentioned object is to generate plasma in a cusp magnetic field formed in the vicinity of the first electrode by the first magnetic device means, and the substrate placed on the second electrode by the plasma. In the substrate processing method for processing a substrate, the magnetic flux is controlled so that a magnetic flux that forms a cusp magnetic field and that crosses the second electrode crosses the outside of the substrate. In the substrate processing method for generating a plasma in a cusp magnetic field formed in the vicinity of the first electrode by means, and processing the substrate placed on the second electrode by the plasma, The second magnetic device means controls the magnetic flux that forms the cusp magnetic field to process the substrate such that the magnetic flux that forms the cusp magnetic field and that crosses the second electrode crosses the outside of the substrate. Further, the substrate processing method of further generating plasma in the cusp magnetic field formed in the vicinity of the first electrode by the first magnetic device means to form a thin film on the substrate placed on the second electrode by the plasma. In the above, the second magnetic device means provided on the side of the second electrode controls the magnetic flux that forms the cusp magnetic field so that the density distribution of the charged particles incident on the substrate from the plasma is substantially uniform on the substrate. This is achieved by forming a thin film. Furthermore, the present invention provides a substrate processing apparatus, mounting means for mounting a substrate, and electrode means provided so as to face the mounting means,
The first magnetic device means for forming a cusp magnetic field between the electrode means and the mounting means, the plasma generating means for generating plasma in the magnetic field formed by the first magnetic device means, and the substrate mounting means A second magnetic device means for generating a magnetic field that controls the distribution of the magnetic flux so that the magnetic flux that crosses the mounting means out of the magnetic flux that exists on the side and that forms the cusp magnetic field passes through the outside of the substrate on which the magnetic field is mounted. It is achieved by configuring. [Operation] The operation of the above means will be described below when the present invention is applied to the sputtering film forming apparatus. In a configuration in which a target electrode and a substrate electrode are arranged to face each other, a cusp magnetic field is formed between the electrodes by a magnetic device on the target side and a substrate side, and plasma is confined between the electrodes in the magnetic device, the magnetic device on the substrate side. By constructing a magnetic device in which the magnetic field lines of the target side magnetic device are guided to the periphery of the substrate without traversing the central part of the substrate, the magnetic field lines of the target side magnetic device are pushed onto the target by the magnetic field lines of the substrate side magnetic device and Is formed along the surface of the target, confines high-density plasma on the target in a wide range, and the magnetic field lines of the magnetic device on the substrate side that press the magnetic field lines of the target side magnetic device into the target must cross the central part of the substrate. Electrons in the plasma confined on the target are guided to the substrate because they are guided around the substrate without Do not concentrate incident. The area of the target that is corroded by sputtering due to this plasma is wide, and the utilization efficiency of the target is improved, high-speed film formation and a good film thickness distribution can be obtained. [Embodiment] A first embodiment of the present invention will be described below with reference to FIG. A target electrode 4 is attached to the opening 2 of the vacuum container 1 via an insulator 3. A target 5 made of a film forming material is provided on the vacuum chamber side of the target electrode 4, a target coil 6 for generating a magnetic field and a yoke 7 are provided on the atmosphere side, and a discharge is generated between the target 5 and the target 5 on the outer circumference thereof. The anode 28 is attached to the vacuum container 1 via the insulator 8 with a distance from the target that does not cause the above phenomenon.
The yoke 7 is used to enhance the leakage magnetic flux density generated by the target coil 6. The potential of the anode 28 may be floating, ground, or any positive or negative voltage as required. A substrate electrode 10 on which a substrate 25 is placed is provided in one opening 9 of the vacuum container 1, and the target 5 and the surface of the substrate electrode 10 are surrounded by an insulator 11 having a vacuum sealing function around the substrate electrode 10. A substrate holder 12 movable in a vertical direction and a shield 14 around the substrate holder 12 are fixed to the vacuum container 1 via an insulator 13 having a vacuum sealing function. An outer coil 17 is mounted in a coil container 16 which is mounted in the vacuum container 1 in a vacuum-sealed state centering on the substrate electrode 10. Furthermore, the in-substrate coil 30 is housed inside the substrate electrode 10. The substrate electrode 10 is water-cooled or heated and kept at a constant temperature. At the center of the substrate electrode 10, there is a cooling gas introduction pipe 29, which can
A temperature control gas such as Ar is introduced between and. The inside of the vacuum container 1 is evacuated by the evacuation means 18 and is maintained at a pressure of typically 10 ³ Torr by the gas introduction means 19. A target power source 20, a high frequency power source 21, a DC power source 22, a target coil power source 23, an outside-board coil power source 24 are connected to the target electrode 4, the substrate electrode 10, the substrate retainer 12, the target coil 6, the outside coil 17 and the inside coil 30, respectively. The in-board coil power supply 31 and the vacuum chamber 1 are connected to the ground. The high frequency power supply 21 is used when applying a DC bias voltage to the substrate surface, and the DC power supply is used when applying a high frequency bias.
No 22 is required. When a high frequency bias voltage is applied, the substrate retainer 12 is made of an insulating material for shielding high frequency plasma. The target coil 6 and the target coil power supply 23 are not limited to electromagnets, and permanent magnets that generate a magnetic field equivalent thereto may be used. The substrate 25 subjected to the sputtering film formation process is placed on the substrate electrode 10 by the transport mechanism (not shown) with the substrate holder 12 moved to the target 5 side, and then held by the substrate holder 12. The present embodiment having the above configuration operates as follows. The substrate 25 transported by a transport mechanism (not shown) is placed on the substrate electrode 10 and then fixed by the substrate retainer 12.
After evacuating the inside of the vacuum container 1 to a high vacuum by the exhaust means 18,
Ar gas is introduced by the gas introduction means 19 to maintain a predetermined sputtering pressure. A DC bias voltage is applied from the DC power source 22 to the surface of the substrate 25 through the substrate retainer 12, or a high frequency power is applied to the substrate electrode 10 from the high frequency power source 21 to generate high frequency plasma on the substrate 25, and a bias voltage is applied. The induction keeps the substrate surface at a negative bias potential. The target coil power supply 23, the outside-board coil power supply 24, and the inside-board coil power supply 31 generate magnetic fields in the same direction in the target coil 6 and the inside-board coil 30, respectively, and the outside-board coil 17 in the opposite direction.
A magnetic field line 26 is formed by applying an electric current so that the magnetic field generates a magnetic field. The simulation calculation result of the magnetic field lines 26 is shown in FIG. The main calculation conditions are as follows: the center magnetic flux density of the target coil 6 is 338G, and the in-board coil 30 is 280G.
The off-board coil 17 is 250G. Due to the influence of the magnetic flux c generated between the inner and outer coils on the substrate side, of the magnetic fluxes a and b generated from the central tip of the yoke 7 of the target coil 6, the magnetic flux a is formed along the surface of the target 5,
The magnetic flux b is formed so as to enter the inside of the in-substrate coil 30. Next, by applying sputtering power from the target power source 20 to the target electrode 4, high density plasma is generated from the target 5 to the surface of the substrate electrode 10 so as to be confined in the magnetic flux a and magnetic flux c orthogonal to the electric field. At this time, on the target 5, it was observed that the area of the magnetic flux a had a higher plasma density than the area of the magnetic flux b. A large amount of secondary electrons are generated mainly from the target due to the ion injection from the plasma in the region of the magnetic flux a, and the secondary electrons are accelerated into the plasma at a high speed due to the potential difference (several hundreds of volts) between the target and the plasma and are emitted into the plasma. It The high-energy electrons move in a spiral motion along the magnetic lines of force a and c passing through the plasma, but the magnetic flux a forms an arc on the target, and therefore electrons are confined in this magnetic flux except for loss due to collision. To be The electrons in the magnetic flux c flow toward the substrate 25 along the magnetic flux c, but since the magnetic flux c does not pass over the substrate 25 and crosses the outer periphery of the substrate 25, high-energy electrons do not enter the substrate 25. On the other hand, the electrons in the magnetic flux b are mainly those in which high-energy electrons on the magnetic flux a have diffused due to collision with ions, neutral particles, etc., and the electrons are sufficiently slow. The electrons move along the magnetic flux b onto the substrate 25, but since the magnetic flux b spreads over the substrate 25 with a substantially uniform magnetic flux density than the sufficiently small area of the center of the target 5, the incidence of electrons on the substrate 25 is average. Be converted. Further, since the magnetic flux b is incident on the substrate 25 with a uniform density, the amount of ions incident along the magnetic flux b from the plasma 27 on the surface of the substrate 25 to which the bias potential is applied is also averaged. Further, the magnetic field on the target is such that the magnetic flux a is pressure-bonded by the magnetic flux c, and high-density plasma can be formed in a wide range. Next, FIG. 3 shows the ion current and electron energy density flowing into the substrate 25 with respect to the central magnetic flux density of the in-substrate coil 30. A bias voltage of -100V was applied to the substrate, the center magnetic flux density of the target coil was 338G, and the center magnetic flux density of the coil outside the substrate was 248G. When the magnetic flux density of the in-substrate coil is 0, the magnetic field distribution is the same as the conventional cusp magnetic field, and the bias toward the center is eliminated as the central magnetic flux density of the in-substrate coil is increased, and when the ion density exceeds 260 G The incident amount becomes uniform and high energy electrons are not incident. Further, the temperature of the substrate 25 is controlled by introducing a temperature control gas between the substrate electrode 10 and the substrate 25 which are kept at a constant temperature,
The film quality can be maintained. With the configuration described above, abnormal temperature rise at the center of the substrate and uneven distribution of materials to minute steps and holes due to uneven distribution of incident ion amount, which have been caused by the conventional cusp magnetic field bias sputtering method, are eliminated, and the deposition rate is high. A bias sputtering method and apparatus having uniform film quality and having sufficient migration performance over the entire surface of the substrate can be realized. FIG. 4 shows a second embodiment of the present invention. The configuration is the same as that of the first embodiment except for the in-board coil 30 and the outer coil 17. In this embodiment, the substrate is used as the substrate side magnetic device.
A substrate-side permanent magnet 33 formed in an annular shape so as to surround the substrate 25 on the back surface of 25 is used. The permanent magnet 33 forms a cusp magnetic field in cooperation with the target coil 6 by the magnetic field lines emitted to the outside of the ring, and the magnetic field lines emitted to the inside of the ring can obtain the same magnetic field line distribution as in the first embodiment. The same effect can be obtained. FIG. 5 shows a third embodiment of the present invention. The configuration is the same as that of the first embodiment except for the in-board coil 30 and the outer coil 17. In this embodiment, a substrate coil 17 'is installed as a substrate-side magnetic device, and a substrate-side yoke 32 located inside the substrate coil 17' and on the side of the substrate coil 17 'opposite to the target 5 is placed. As a result, the magnetic force lines generated by the substrate coil 17 'are attracted to the central axis side magnetic force line of the substrate coil 17' to the substrate side yoke 32. As a result, a magnetic force line distribution similar to that of FIG. 1 is obtained, which is the same as the first embodiment. The effect of can be obtained. [Advantages of the Invention] According to the present invention, the cusp magnetic field formed by a pair of facing magnets is further improved by a magnetic device provided on the substrate side so that magnetic force lines are guided to the periphery of the substrate so as not to cross the center of the substrate. The cusp magnetic field makes it possible to control the density distribution of charged particles such as electrons and ions entering the substrate from the plasma confined in the cusp magnetic field, and the substrate is uniformly processed over almost the entire surface. The effect that can be obtained is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a first embodiment of the present invention, FIG. 2 is a view showing a magnetic field distribution between target substrates in the first embodiment of the present invention, and FIG. Is a diagram showing data of ion current density and substrate electron inflow energy density in the first embodiment of the present invention, FIG. 4 is a longitudinal sectional view of the second embodiment of the present invention, and FIG. FIG. 6 is a longitudinal sectional view of a third embodiment of the invention, and FIG. 6 is a diagram showing ion current and inflowing electron energy distribution data in a conventional cusp magnetic field sputtering apparatus. Explanation of reference numerals 1 ... vacuum container, 3 ... insulator, 4 ... target electrode 5 ... target, 6 ... target coil 7 ... yoke, 8 ... insulator, 9 ... opening, 10 ... substrate Electrode, 11 ... Insulator, 12 ... Board holder 13 ... Insulator, 14 ... Shield, 15 ... Opening 16 ... Coil container, 17 ... Outside-board coil 18 ... Exhaust means, 19 ... Gas Introducing means 20 …… Target power supply, 21 …… High frequency power supply 22 …… DC power supply, 23 …… Target coil power supply 24 …… Outside substrate coil power supply, 25 …… Substrate, 26 …… Magnetic field 27 …… Plasma, 28 …… Anode 29: Cooling gas introduction tube, 30: In-board coil 31: In-board coil power supply, 33: Permanent magnet

Claims (1)

(57) [Claims] A substrate processing method for generating a plasma in a cusp magnetic field formed in the vicinity of a first electrode by a first magnetic device means to process a substrate placed on a second electrode by the plasma, wherein the cusp magnetic field is The substrate processing method is characterized in that the substrate is processed by controlling the magnetic flux so that the magnetic flux that crosses the second electrode crosses the outside of the substrate among the magnetic flux that forms the. 2. The substrate processing method according to claim 1, wherein the first electrode is a sputter electrode provided with a sputter target, and the process of the substrate is a sputter film forming process. 3. The substrate processing method according to claim 1, wherein the processing of the substrate is performed while applying a voltage to the substrate. 4. The substrate processing method according to claim 1, wherein the processing of the substrate is performed while controlling the temperature of the substrate. 5. A substrate processing method, wherein plasma is generated in a cusp magnetic field formed in the vicinity of the first electrode by the first magnetic device means, and the substrate placed on the second electrode is processed by the plasma. Of the magnetic flux that forms the cusp magnetic field by controlling the magnetic flux that forms the cusp magnetic field by the second magnetic device means provided on the side of the electrode, the magnetic flux that crosses the second electrode crosses the outside of the substrate. A method for treating a substrate, which comprises treating the substrate in this manner. 6. The substrate processing method according to claim 5, wherein the first electrode is a sputtering electrode provided with a sputtering target, and the processing of the substrate is a sputtering film forming processing. 7. The substrate processing method according to claim 5, wherein the processing of the substrate is performed while applying a voltage to the substrate. 8. The substrate processing method according to claim 5, wherein the processing of the substrate is performed while controlling the temperature of the substrate. 9. A substrate processing method for forming a thin film on a substrate placed on a second electrode by generating plasma in a cusp magnetic field formed in the vicinity of a first electrode by a first magnetic device means, With the second magnetic device provided on the second electrode side controlling the magnetic flux forming the cusp magnetic field to make the density distribution of charged particles incident on the substrate from the plasma substantially uniform. A substrate processing method comprising forming a thin film on the substrate. 10. 10. The thin film formed on the substrate is formed by a sputtering film forming process.
Substrate processing method according to item. 11. The substrate processing method according to claim 9, wherein the sputtering film formation process is performed while applying a voltage to the substrate. 12. The substrate processing method according to claim 9, wherein the sputtering film formation process is performed while controlling the temperature of the substrate. 13. Mounting means for mounting the substrate; electrode means provided to face the mounting means; first magnetic device means for forming a cusp magnetic field between the electrode means and the mounting means; The plasma generating means for generating plasma in the magnetic field formed by the first magnetic device means, and the magnetic flux which is on the side of the substrate mounting means and which forms the cusp magnetic field crosses the mounting means. 2. A substrate processing apparatus, comprising: a second magnetic device unit that generates a magnetic field that controls the distribution of the magnetic flux so as to pass outside the substrate on which it is placed. 14． 14. The substrate processing apparatus according to claim 13, wherein the electrode means is a sputter electrode provided with a sputter target. 15. 14. The substrate processing apparatus according to claim 13, wherein the placing unit includes a voltage applying unit that applies a voltage to the substrate. 16. 14. The substrate processing apparatus according to claim 13, wherein the placing unit includes a temperature control unit that controls the temperature of the substrate.